阅读说明：本技术 一种电阻点焊装置和方法 (Resistance spot welding device and method ) 是由 张永强 付参 王鹏博 伊日贵 鞠建斌 李学涛 王松涛 章军 于 2021-08-20 设计创作，主要内容包括：本发明公开了一种电阻点焊装置和方法,包括：第一电极,包括凸起工作区和第一工作区,凸起工作区设置在第一工作区的中部；第二电极,包括第二工作区；当凸起工作区和第一工作区与第一试板接触,第二工作区与第二试板接触,且第一电极与第二电极通电时,第一电极与第二电极配合,使第一试板和第二试板之间形成目标焊核,其中,第一试板的厚度小于第二试板的厚度。本申请可以依赖于凸起工作区的电流密度大的特点,将焊核成核的位置偏移至第一试板和第二试板之间的位置,可以对不同厚度的试板进行高效焊接,大大提高了两个厚度不同的试板之间的连接强度。(The invention discloses a resistance spot welding device and a method, which comprises the following steps: the first electrode comprises a convex working area and a first working area, and the convex working area is arranged in the middle of the first working area; a second electrode including a second working region; when the protruding working area and the first working area are in contact with the first test board, the second working area is in contact with the second test board, and the first electrode and the second electrode are electrified, the first electrode is matched with the second electrode, so that a target weld nugget is formed between the first test board and the second test board, wherein the thickness of the first test board is smaller than that of the second test board. This application can rely on the characteristics that the current density of protruding workspace is big, and the offset that will weld the nuclear nucleation to the position between first examination board and the second examination board can carry out high-efficient welding to the examination board of different thickness, has improved the joint strength between the examination board of two thickness differences greatly.)

1. A resistance spot welding apparatus, characterized in that the apparatus comprises:

the first electrode comprises a raised working area and a first working area, and the raised working area is arranged in the middle of the first working area;

the second electrode comprises a second working area;

when the protruding working area is in contact with the first test board, the second working area is in contact with the second test board, and the first electrode is electrified with the second electrode, the first electrode is matched with the second electrode, so that a target welding core is formed between the first test board and the second test board, wherein the thickness of the first test board is smaller than that of the second test board.

2. The apparatus of claim 1, wherein the diameter of the first working area is equal to or greater than the diameter of the second working area.

3. The apparatus of claim 1, wherein the radius of curvature of the first working area is greater than the radius of curvature of the second working area.

4. The device of claim 1, wherein the diameter of the raised working area is smaller than the diameter of the second working area.

5. The apparatus of claim 1, wherein the radius of curvature of the convex working area is less than the radius of curvature of the second working area.

6. A resistance spot welding method, characterized in that the method comprises:

placing a first test plate and a second test plate between a first electrode and a second electrode, and enabling the first test plate to be in contact with the protruding working area of the first electrode, and enabling the second test plate to be in contact with the second working area of the second electrode, wherein the thickness of the first test plate is smaller than that of the second test plate;

and applying pressure and welding current to the first electrode and the second electrode to form a target weld nugget between the first test plate and the second test plate.

7. The method of claim 6, wherein applying pressure and welding current to the first electrode and the second electrode to form a target nugget between the first test panel and the second test panel comprises:

and applying pressure and welding current to the first electrode and the second electrode to form the target weld nugget between the contact surfaces of the first test plate and the second test plate.

8. The method of claim 7, wherein applying pressure and welding current to the first electrode and the second electrode to form the target nugget between the contact surfaces of the first test panel and the second test panel comprises:

applying a first pressure and a first welding current to the first electrode and the second electrode to form a first weld nugget between contact surfaces of the first test plate and the second test plate;

and applying a second pressure and a second welding current to the first electrode and the second electrode to form a second weld nugget in a middle area of the total thickness of the first test plate and the second test plate, wherein the target weld nugget comprises the first weld nugget and the second weld nugget.

9. The method of claim 7, wherein applying pressure and welding current to the first electrode and the second electrode to form the target nugget between the contact surfaces of the first test panel and the second test panel comprises:

applying a third pressure and a third welding current to the first electrode and the second electrode to form a third weld nugget between the contact surfaces of the first test plate and the second test plate;

and applying fourth pressure and fourth welding current to the first electrode and the second electrode to enable the third weld nugget to grow towards the second test plate, and taking the grown third weld nugget as the target weld nugget.

10. The method of claim 7, wherein applying pressure and welding current to the first electrode and the second electrode to form the target nugget between the contact surfaces of the first test panel and the second test panel when an intermediate test panel is included between the first test panel and the second test panel, specifically comprises:

applying a fifth pressure and a fifth welding current to the first electrode and the second electrode to form a fourth weld nugget between the contact surfaces of the first test plate and the middle test plate;

and applying sixth pressure and sixth welding current to the first electrode and the second electrode to form a fifth weld nugget between the contact surfaces of the intermediate test plate and the second test plate, wherein the target weld nugget comprises the fourth weld nugget and the fifth weld nugget.

Technical Field

The invention relates to the technical field of resistance spot welding, in particular to a resistance spot welding device and a resistance spot welding method.

Background

Resistance spot welding refers to a method of connecting at least two test panels together by passing current through the test panels under pressure (the test panels are a general term for materials to be welded), and combining the test panels to locally heat the test panels by using generated resistance heat as a heat source to finally form a weld nugget between the test panels. At present, resistance spot welding has been widely used for joining of metallic materials.

In the related art, when the thicknesses of at least two test boards are the same, a nugget can be smoothly formed between the at least two test boards (specifically, in the middle of the total thickness of the at least two test boards), so that the at least two test boards can be stably connected. However, when at least two test boards have different thicknesses, it means that the positions where the nuggets are required to be formed are shifted (the shift is relative to the case when the test boards have the same thickness), resulting in a lower strength of the connection between the two test boards having different thicknesses.

Disclosure of Invention

The embodiment of the application provides a resistance spot welding device and a resistance spot welding method, solves the technical problem that in the prior art, the connection strength of a welding core between two test plates with different thicknesses is low, and achieves the technical effect of improving the connection strength between the two test plates with different thicknesses.

In a first aspect, the present application provides a resistance spot welding device comprising:

the first electrode comprises a convex working area and a first working area, and the convex working area is arranged in the middle of the first working area;

a second electrode including a second working region;

when the protruding working area is in contact with the first test plate, the second working area is in contact with the second test plate, and the first electrode and the second electrode are electrified, the first electrode is matched with the second electrode, so that a target weld core is formed between the first test plate and the second test plate, wherein the thickness of the first test plate is smaller than that of the second test plate.

Further, the diameter of the first working area is larger than or equal to that of the second working area.

Further, the radius of curvature of the first working area is greater than the radius of curvature of the second working area.

Further, the diameter of the convex working area is smaller than the diameter of the second working area.

Further, the radius of curvature of the convex working area is smaller than the radius of curvature of the second working area.

In a second aspect, the present application provides a resistance spot welding method comprising:

placing a first test board and a second test board between a first electrode and a second electrode, and enabling the first test board to be in contact with the protruding working area of the first electrode, and enabling the second test board to be in contact with the second working area of the second electrode, wherein the thickness of the first test board is smaller than that of the second test board;

and applying pressure and welding current to the first electrode and the second electrode to form a target weld nugget between the first test plate and the second test plate.

Further, applying pressure and welding current to the first electrode and the second electrode to form a target weld nugget between the first test plate and the second test plate, specifically comprising:

and applying pressure and welding current to the first electrode and the second electrode to form a target weld nugget between the contact surfaces of the first test plate and the second test plate.

Further, applying pressure and welding current to the first electrode and the second electrode to form a target weld nugget between the contact surfaces of the first test plate and the second test plate, specifically comprising:

applying a first pressure and a first welding current to the first electrode and the second electrode to form a first welding core between contact surfaces of the first test plate and the second test plate;

applying a second pressure and a second welding current to the first electrode and the second electrode to form a second weld nugget in a middle area of the total thickness of the first test plate and the second test plate; wherein the target nugget includes a first nugget and a second nugget.

Further, applying pressure and welding current to the first electrode and the second electrode to form a target weld nugget between the contact surfaces of the first test plate and the second test plate, specifically comprising:

applying a third pressure and a third welding current to the first electrode and the second electrode to form a third weld nugget between the contact surfaces of the first test plate and the second test plate;

and applying fourth pressure and fourth welding current to the first electrode and the second electrode to enable the third weld nugget to grow towards the second test plate, and taking the grown third weld nugget as a target weld nugget.

Further, when an intermediate test plate is included between the first test plate and the second test plate, applying pressure and welding current to the first electrode and the second electrode to form a target weld nugget between contact surfaces of the first test plate and the second test plate, specifically including:

applying a fifth pressure and a fifth welding current to the first electrode and the second electrode to form a fourth weld nugget between the contact surfaces of the first test plate and the middle test plate;

and applying sixth pressure and sixth welding current to the first electrode and the second electrode to form a fifth welding core between the contact surfaces of the middle test plate and the second test plate, wherein the target welding core comprises a fourth welding core and a fifth welding core.

One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

the application provides the first electrode including protruding workspace and first workspace to and the second electrode including the second workspace, when welding the test panel, can rely on the characteristics that the current density of protruding workspace is big, the offset that will weld the nuclear nucleation to the interfacial position between first test panel and the second test panel (first test panel and second test panel thickness are inequality, and the former is less than the latter), can carry out high-efficient welding to the test panel of different thickness, the joint strength between the test panel of two different thicknesses has been improved greatly, just also greatly reduced the welded degree of difficulty.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

Fig. 1 is a schematic structural view of a resistance spot welding apparatus provided in the related art;

FIG. 2 is a schematic structural view of a resistance spot welding apparatus according to the present application;

FIG. 3 is a schematic view of a structure of two test panels before welding by using the apparatus shown in FIG. 2;

FIG. 4 is a schematic structural diagram illustrating the formation of a first nugget when two test panels are welded using the apparatus shown in FIG. 2;

FIG. 5 is a schematic structural diagram illustrating the formation of a second nugget when two test panels are welded using the apparatus shown in FIG. 2;

FIG. 6 is a schematic diagram of a three-layer test panel before welding using the apparatus shown in FIG. 2;

FIG. 7 is a schematic diagram illustrating a first weld nugget formed when the apparatus shown in FIG. 2 is used to weld three test panels;

FIG. 8 is a schematic diagram illustrating a second nugget formed when the apparatus shown in FIG. 2 is used to weld three test panels;

fig. 9 is a flowchart of a resistance spot welding method provided by the present application.

Reference numerals:

1-a first electrode, 11-a convex working area, 12-a first working area, 13-a first transition area, 14-a first electrode body, 15-a first cooling groove, 2-a second electrode, 21-a second working area, 22-a second transition area, 23-a second electrode body, 24-a second cooling groove, 3-a first test plate, 4-a second test plate, 5-an intermediate test plate, 6-a welding core and 7-a welding core.

Detailed Description

The embodiment of the application provides a resistance spot welding device, has solved the lower technical problem of joint strength between the test panel of two thickness differences among the prior art.

In order to solve the technical problems, the general idea of the embodiment of the application is as follows:

a resistance spot welding device, the device comprising: the first electrode 1 comprises a convex working area 11 and a first working area 12, wherein the convex working area 11 is arranged in the middle of the first working area 12; a second electrode 2 comprising a second working area 21; when the protruding working area 11 contacts the first test plate 3, the second working area 21 contacts the second test plate 4, and the first electrode 1 and the second electrode 2 are electrified, the first electrode 1 is matched with the second electrode 2, so that a target welding core is formed between the first test plate 3 and the second test plate 4, wherein the thickness of the first test plate 3 is smaller than that of the second test plate 4.

The application provides first electrode 1 including protruding workspace 11 and first workspace 12, and second electrode 2 including second workspace 21, when welding the test panel, can rely on the characteristics that protruding workspace 11's current density is big, the position skew that will weld the nuclear nucleation to first test panel 3 and second test panel 4 (the thickness of first test panel 3 and second test panel 4 is inequality, and the former is less than the latter), can carry out high-efficient welding to the test panel of different thickness, the resistance spot welding device that this embodiment provided has improved the joint strength between the test panel of two thickness differences greatly, just also greatly reduced the welded degree of difficulty.

In order to better understand the technical solution, the technical solution will be described in detail with reference to the drawings and the specific embodiments.

First, it is stated that the term "and/or" appearing herein is merely one type of associative relationship that describes an associated object, meaning that three types of relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

In the related art, resistance spot welding is performed using two electrodes as shown in fig. 1. The upper and lower electrodes shown in fig. 1 are the same, and are respectively referred to as upper and lower electrodes according to their positions in the figure. Both the upper and lower electrodes include a working region a, a transition region B, a cooling bath C, and an electrode body D (note that the upper electrode in fig. 1 is not indicated with a reference numeral). In resistance spot welding, test plates (i.e., materials to be welded, two test plates are taken as an example here and include a first test plate 3 and a second test plate 4, the first test plate 3 and the second test plate 4 are placed between an upper electrode and a lower electrode, the upper electrode and the lower electrode are controlled to be close to each other, the upper electrode is in contact with the first test plate 3, the lower electrode is in contact with the second test plate 4, and pressure and welding current are applied to the first electrode 1 and the second electrode 2, so that a weld nugget is formed between the first test plate 3 and the second test plate 4.

It should be noted that the upper electrode and the lower electrode are the same, so that the current density flowing from the upper electrode (or the lower electrode) to the lower electrode (or the upper electrode) is not changed by the electrode itself. When the first test plate 3 and the second test plate 4 are welded using the upper electrode and the lower electrode, the following two cases can be specifically classified:

(case one) the first test plate 3 and the second test plate 4 are made of the same material

When the first test board 3 and the second test board 4 are made of the same material, no matter whether the first test board 3 and the second test board 4 are the same in thickness, the positions where the nuggets are formed are the middle positions of the total thickness of the first test board 3 and the second test board 4 due to resistance distribution and electrode heat dissipation. When the thickness of the first test panel 3 and the second test panel 4 are the same, the central position of the total thickness of the first test panel 3 and the second test panel 4 is the most ideal nucleation position, and the upper electrode and the lower electrode shown in fig. 1 can be used to nucleate at the position more accurately. However, when the thicknesses of the first test board 3 and the second test board 4 are different, for example, the thickness of the first test board 3 is 1mm, and the thickness of the second test board 4 is 2mm, the nugget will nucleate at a position in the middle of the total thickness of the first test board 3 and the second test board 4, that is, a nugget is formed at a position of 1.5mm, and the position is located inside the second test board 4, in order to connect the first test board 3 and the second test board 4, a large nugget is needed to be realized, and the energy of the time consumed for forming a large nugget is large, and the appearance quality may be degraded, for example, the depth of the formed indentation may be increased. When the difference between the thicknesses of the first test board 3 and the second test board 4 is larger, the difficulty of forming a nugget that can connect the first test board 3 and the second test board 4 is also larger.

(case two) the first test plate 3 and the second test plate 4 are made of different materials

When the first test panel 3 and the second test panel 4 are made of different materials, the nucleation position between the first test panel 3 and the second test panel 4 may no longer be the middle position of the total thickness, but the nucleation position may be shifted near the middle position toward the side of the test panel having a large resistivity. When the thickness of first examination board 3 and second examination board 4 is not the same, still need form great welding core and can connect first examination board 3 and second examination board 4, and when the thickness difference of first examination board 3 and second examination board 4 is big, the degree of difficulty that forms the welding core that can connect both between first examination board 3 and second examination board 4 also is big.

For example, in the automotive field, the thickness of a vehicle body panel is small, while the thickness of a vehicle body structural member is large, and when the two are welded, the welding difficulty is large. Typically, the body panels are of a relatively low resistivity material. In recent years, in order to meet the demand for weight reduction of vehicle bodies, there is a demand for a material for vehicle body panels that is continuously thinned, and the thickness ratio (i.e., the ratio of the total thickness of the vehicle body panel and the vehicle body structural member to the thickness of the vehicle body panel) is further increased, and the greater the thickness ratio, the more difficult it is to form a nugget that can stably connect between test panels. On the basis of the consideration of the safety of the vehicle body, the strength of the structural member of the vehicle body is continuously increased, and the high-strength steel generally has higher resistivity, so that the deviation of a weld nugget to one side of a thick plate is further aggravated. In the related art, in order to form an effective connection between the thin plate and other materials, it is necessary to increase welding current and welding time, however, this may result in deep weld spots, severe weld spatter, and reduced joint strength. When the covering part is made of a low-melting-point coating material, such as zinc, zinc-aluminum-magnesium and the like, the molten coating is easy to gather around the welding spot to form the welding spot zinc accumulation defect, and the appearance quality of the welding spot is also influenced. On the premise of welding the two parts together, the appearance quality of the automobile body covering part needs to be ensured, and the spot welding device shown in fig. 1 is adopted for welding, so that the following problems can be caused: deep indentation of welding spots, high zinc stacking height and poor appearance quality, and the subsequent electrophoretic painting after manual repair is needed, which causes the increase of manufacturing cost.

In summary, when the electrode welding test plates shown in fig. 1 are adopted, and the thicknesses of the welding test plates are different, the problem that the connection strength between the two test plates with different thicknesses is low exists; when the covering member having a small thickness is required to have an appearance, there is a problem that the quality of the appearance is poor, and when the appearance is restored, there is a problem that the manufacturing cost is increased.

In order to solve the above-mentioned technical problem, the present application provides a resistance spot welding apparatus as shown in fig. 2, the apparatus including:

the first electrode 1 comprises a convex working area 11 and a first working area 12, wherein the convex working area 11 is arranged in the middle of the first working area 12, and the convex working area 11 protrudes outwards from the middle of the first working area 12 to form a bulge. And a second electrode 2 comprising a second working area 21.

When the protruding working area 11 contacts the first test plate 3, the second working area 21 contacts the second test plate 4, and the first electrode 1 and the second electrode 2 are electrified, the first electrode 1 is matched with the second electrode 2, so that a target welding core is formed between the first test plate 3 and the second test plate 4, wherein the thickness of the first test plate 3 is smaller than that of the second test plate 4.

The working area of the first electrode 1 provided by this embodiment has two areas, including the protruding working area 11 and the first working area 12, and can change the current density distribution in the welding process, and then can control the nucleation position of the weld nuclei, so as to achieve the purposes of improving the connection strength between two test panels with different thicknesses, improving the appearance quality of the first test panel 3, and reducing the cost and time spent on appearance repair at the later stage (the specific implementation principle will be described later).

As shown in fig. 2, the first electrode 1 comprises, in addition to the convex working region 11 and the first working region 12, a first cooling groove 15, a first electrode body 14 and a first transition region 13. The first cooling tank 15 is disposed inside the first electrode body 14 and is used for containing cooling water to accelerate heat dissipation of the first electrode 1. The first transition area 13 is used for carrying the protruding working area 11 and the first working area 12, i.e. the protruding working area 11 and the first working area 12 are located at the front end of the first transition area 13. The second electrode 2 comprises, in addition to the second working zone 21, a second cooling channel 24, a second electrode body 23 and a second transition zone 22. The second cooling tank 24 is disposed inside the second electrode body 23 and is used for containing cooling water to accelerate heat dissipation of the second electrode 2. The second transition area 22 is used to carry the second working area 21, i.e. the second working area 21 is located at the front end of the second transition area 22.

When welding the test panel, the first electrode 1 and the second electrode 2 are oppositely arranged, and the convex working area 11 and the first working area 12 of the first electrode 1 are opposite to the second working area 21 of the second electrode 2. The first electrode 1 and the second electrode 2 are connected to a welding power source so that the first electrode 1 and the second electrode 2 can generate a current when they contact a test panel.

When the first test plate 3 and the second test plate 4 are welded using the spot welding apparatus as shown in fig. 2, the following two stages may be included:

[ STAGE one ]

The first test plate 3 and the second test plate 4 are placed between the first electrode 1 and the second electrode 2, and the first electrode 1 and the second electrode 2 move toward each other (with respect to fig. 3, the first electrode 1 may move downward while the second electrode 2 does not move, the first electrode 1 may not move while the second electrode 2 moves upward, or the first electrode 1 may move downward while the second electrode 2 moves upward). As shown in fig. 3, after the convex working area 11 is contacted with the first test plate 3 and the second working area 21 is contacted with the second test plate 4, pressure and welding current are applied to the first electrode 1 and the second electrode 2; the current flowing through the first electrode 1 and the second electrode 2 is the same, but the first electrode 1 at this time transmits the current to the first test panel 3 only through the embossed working area 11, and the current density of the embossed working area 11 is large compared to the current density at other positions of the spot welding apparatus (including the test panel itself). And the nucleation site of the nugget is usually biased to a site with a higher current density, an initial nugget (i.e., nugget 6) may be formed at (or near) the interface of the first test panel 3 and the second test panel 4, as shown in fig. 4. When the initial nugget 6 is formed, since the current density of the bump working area 11 is high and the temperature is high, the first test board 3 is melted (but only the position where the bump working area 11 contacts the first test board 3 is melted), and the bump working area 11 gradually sinks into the first test board 3.

[ STAGE II ]

When the protruding working area 11 is completely sunk into the first test board 3, the first working area 12 is gradually contacted with the first test board 3, and as the contact area between the first working area 12 and the first test board 3 is gradually increased, the current density between the first test board 3 and the first electrode 1 is also gradually reduced, at this time, two situations may occur inside the first test board 3 and the second test board 4.

One of the cases is: the nugget formed in the first stage gradually increases toward the second test board 4 (for fig. 4, the nugget is shifted downward to form a nugget 7 shown in fig. 5), and the nugget also grows at the interface between the first test board 3 and the second test board 4, so that the welding between the first test board 3 and the second test board 4 can be firmer.

The other situation is that: a new nugget 7 is formed at a position near the middle of the total thickness of the first test panel 3 and the second test panel 4, and this nugget 7 gradually grows with the passage of time, and at the same time, the nugget 6 formed in the stage one gradually grows, and the two nuggets eventually join together to form a final nugget (the nugget 6 and the nugget 7 join together) that joins the first test panel 3 and the second test panel 4.

In either case, the following process proceeds as follows: in the first stage, the first test board 3 in the contact area is plastically/elastically deformed due to the higher temperature of the protruding working area 11, if a low-melting-point coating is present on the surface of the first test board 3, the coating metal is melted, and the melted coating metal and the first test board 3 subjected to plastic deformation are extruded onto the first test board 3 (particularly, around the periphery in contact with the protruding working area 11), which may affect the appearance. When the first working area 12 is brought into contact with the first test plate 3, the extruded plating layer and the portion of the first test plate 3 that is plastically deformed can be flattened, thereby improving the quality of appearance. In addition, compared with the stage one, the current density between the protruding working area 11 and the first test board 3 is greatly reduced, the heat dissipation is accelerated, and then the temperature is reduced, the surface coating of the first test board 3 contacting with the first working area 11 is melted, and the plastic deformation of the surface of the first test board 3 is inhibited, so that the damage to the surface of the first test board 3 is reduced or avoided.

In summary, the present embodiment provides the first electrode 1 including the protruding working area 11 and the first working area 12, and the second electrode 2 including the second working area 21, when welding a test plate, the position of nucleation of a weld nugget can be shifted to the interface position between the first test plate 3 and the second test plate 4 (the first test plate 3 and the second test plate 4 have different thicknesses, and the former is smaller than the latter) depending on the characteristic that the current density of the protruding working area 11 is large, so that the test plates with different thicknesses can be efficiently welded, and compared with the electrode shown in fig. 1, the resistance spot welding device provided in the present embodiment greatly improves the connection strength between the two test plates with different thicknesses, and thus greatly reduces the difficulty of welding; meanwhile, the first working area 12 can be used for flattening the plating layer on the first test plate 3 around the protruding working area 11 and the metal which is subjected to plastic deformation, so that the appearance of the first test plate 3 is improved, the appearance does not need to be improved at the later stage, and the cost is saved.

For example, when the thickness of the car body covering part (i.e. the first test plate 3) is thinner, and the thickness of the car body structural part (i.e. the second test plate 4) is thicker, and the car body covering part is positioned on the surface of the car body, the appearance quality requirement exists, and the resistance spot welding device provided by the embodiment can ensure the appearance quality under the condition of ensuring the welding quality of the car body covering part and the car body structural part.

The convex working area 11 of the first electrode 1 is a convex protruding from the inside of the first working area 12, and can be a part of a sphere or an arc surface; the first working area 12 may be a plane or a curved surface. The second working area 21 of the second electrode 2 may be a plane or a curved surface.

The quality of the welding test plate of the resistance spot welding device provided by the embodiment can be further improved by adjusting the physical parameters of the first electrode 1 and the second electrode 2, and the quality specifically includes the following modes and various combinations of the following modes.

The diameter of the first working area 12 is greater than or equal to the diameter of the second working area 21.

In the process of the second stage, when the diameter of the first working area 12 is larger than or equal to the diameter of the second working area 21, the contact area between the first working area 12 and the first test board 3 is larger than or equal to the contact area between the second working area 21 and the second test board 4. The first electrode 1 and the second electrode 2 respectively apply the same pressure to the first test plate 3 and the second test plate 4, the contact area between the first electrode 1 and the first test plate 3 is larger, and the pressure intensity is smaller, so that the trace left on the first test plate 3 by the first electrode 1 is shallower and can be basically ignored, and the appearance quality of the first test plate 3 is further improved. Although the first electrode 1 has the convex working region 11, and the convex working region 11 leaves a small pit on the first test plate 3, the volume of the convex working region 11 itself is small, and the influence on the appearance is negligible.

Also, the convex working area 11 may cause the plated layer or the plastically deformed metal on the first test board 3 to be extruded due to the high temperature. The larger the diameter of the first electrode 1 is, the larger the area of the first electrode 1 is, the lower the pressure born by the first electrode 1 in the second stage is, the smaller the current density is, and the more sufficient the heat dissipation is, further, the lower the surface temperature of the first test plate 3 in contact with the first electrode is, the less the plating layer melting caused below the first electrode 1 is, the smaller the plastic deformation of the first test plate 3 is, and the better the effects of flattening the molten plating layer extruded from the convex working area 11 and the plastic deformation metal are, so that the appearance quality of the first test plate 3 is further improved.

The radius of curvature of the first working area 12 is greater than the radius of curvature of the second working area 21.

The larger the radius of curvature of the working area, the closer the working area is to the plane. When the radius of curvature of the first working area 12 is larger than the radius of curvature of the second working area 21, the first working area 12 is closer to a plane than the second working area 21, and the contact area of the first electrode 1 and the first test plate 3 is larger than the contact area of the second working area 21 and the second test plate 4 in the above-mentioned stage two. When the first electrode 1 and the second electrode 2 respectively conduct the same current to the first test plate 3 and the second test plate 4, the surface temperature of the first test plate 3 in contact with the first electrode 1 is lower than the surface temperature of the second test plate 4 in contact with the second electrode 2, and the surface of the first material 3 is low in temperature, so that the strength is higher, the deformation is not easy to occur, and the indentation is not easy to form. Meanwhile, when the first electrode 1 and the second electrode 2 apply the same pressure to the first test plate 3 and the second test plate 4, respectively, the contact area between the first electrode 1 and the first test plate 3 is larger, and the pressure intensity is smaller, so that traces left on the first test plate 3 by the first electrode 1 are shallower and can be basically ignored, and the appearance quality of the first test plate 3 is further improved.

The diameter of the raised working area 11 is smaller than the diameter of the second working area 21.

In the first stage, when the diameter of the protruding working area 11 is smaller than the diameter of the second working area 21, the current density of the protruding working area 11 is higher than the current density of the second working area 21 under the condition that the same current flows, so that a target nugget can be formed at a position deviated from the first test plate 3 between the first test plate 3 and the second test plate 4 (specifically, between the contact surfaces of the first test plate 3 and the second test plate 4), and the welding quality is improved.

Also, in a practical range, the smaller the diameter of the convex working area 11, the smaller the pits left on the first test panel 3, which is more advantageous for improving the appearance quality of the first test panel 3.

The radius of curvature of the convex working area 11 is smaller than the radius of curvature of the second working area 21.

In the first stage, when the curvature radius of the convex working area 11 is smaller than the curvature radius of the second working area 21, the current density of the convex working area 11 is higher than the current density of the second working area 21 under the condition that the same current flows, so that a target nugget can be formed at a position deviated from the first test plate 3 between the first test plate 3 and the second test plate 4 (specifically, between the contact surfaces of the first test plate 3 and the second test plate 4), and the welding quality is improved.

The above-mentioned first to fourth modes, without conflicting with each other, can be combined with each other to further improve the stability of welding the first test board 3 and the second test board 4 and the appearance quality of the first test board 3.

In the above-mentioned process, the present embodiment is mainly described with respect to the welding of two test panels, and of course, at least one intermediate test panel 5 may be further included between the first test panel 3 and the second test panel 4, that is, the present embodiment may also be applied to the welding of more than two test panels, and the welding of three test panels is now exemplarily described. Wherein, when still including at least one middle test panel 5 between first test panel 3 and the second test panel 4, the total thickness of first test panel 3, second test panel 4 and at least one middle test panel 5 is greater than 2 with the thickness of first test panel 3 than, and when the thickness than big, the effect (the effect includes that welding stability is higher, the nucleation degree of difficulty is lower, appearance quality is better) that adopts the resistance spot welding device that this embodiment provided is better. The welding process of the three-layer test plate still comprises two stages, and in order to distinguish from the above-mentioned [ stage one ] and [ stage two ], the following description is given by taking [ stage three ] and [ stage four ] as names, wherein [ stage one ] and [ stage three ] are similar, and [ stage two ] and [ stage four ] have partial differences.

[ PROBLEM III ]

The first test plate 3, the middle test plate 5 and the second test plate 4 are placed in an overlapping manner and are placed between the first electrode 1 and the second electrode 2, and the first electrode 1 and the second electrode 2 are moved toward each other. As shown in fig. 6, after the convex working area 11 is contacted with the first test plate 3 and the second working area 21 is contacted with the second test plate 4, pressure and welding current are applied to the first electrode 1 and the second electrode 2; the current flowing through the first electrode 1 and the second electrode 2 is the same, but the first electrode 1 at this time transmits the current to the first test panel 3 only through the embossed working area 11, and the current density of the embossed working area 11 is large compared to the current density at other positions of the spot welding apparatus (including the test panel itself). And the nucleation sites of the nuggets are usually biased toward the sites of higher current density, the initial nuggets 6 can be formed at (or near) the interface of the first panel 3 and the intermediate panel 5, as shown in fig. 7. When the initial nugget 6 is formed, the first test board 3 is plastically deformed due to the large current density and high temperature of the protruding working area 11, and the protruding working area 11 gradually sinks into the first test board 3. If the first test plate 3 has a low melting point coating on its surface, the coating in contact with the raised working areas 11 will melt.

[ STAGE IV ]

When the protruding working area 11 is completely sunk into the first test board 3, the first working area 12 is gradually contacted with the first test board 3, and as the contact area between the first working area 12 and the first test board 3 is gradually increased, the current density between the first test board 3 and the first electrode 1 is gradually reduced, which may cause the position of the nugget to gradually shift downward (i.e. shift toward the second test board 4), and when the position shifts, there may be two cases (both cases can refer to fig. 8):

the first condition is as follows: during the displacement, the nugget 6 gradually increases, and the welding between the first test panel 3 and the intermediate test panel 5 can be made more firm. In the fourth stage, the weld nuggets 7 between the first test board 3 and the intermediate test board 5 are increased, which has two functions, on one hand, to further enhance the firmness between the first test board 3 and the intermediate test board 5, and on the other hand, to increase the strength of the weld nuggets 7 to be capable of connecting the intermediate test board 5 and the second test board 4, so that the intermediate test board 5 and the second test board 4 are welded by the weld nuggets 7.

Case two: during the displacement, the nugget 6 gradually increases, and the welding between the first test panel 3 and the intermediate test panel 5 can be made more firm. Meanwhile, due to the reasons of current density, resistance change, heat distribution and the like, a new welding core 7 is formed between the middle test plate 5 and the second test plate 4, the welding core 7 welds the middle test plate 5 and the second test plate 4 together, and along with the increase of the welding core 7, the welding core 7 may be connected with the welding core 6, so that the first test plate 3, the middle test plate 5 and the second test plate 4 are connected more stably.

In the third stage, due to the high temperature of the protruding working area 11, the contact area between the first test board 3 and the protruding working area 11 is plastically deformed, if the first test board 3 has a low-melting-point plating layer, the contacted plating layer is also melted, the melted plating layer and the metal of the first test board 3 which is plastically deformed are pressed onto the first test board 3 (particularly around the contact area with the protruding working area 11), which affects the appearance, and when the first working area 12 is in contact with the first test board 3, the extruded low-melting-point plating layer and the first test board 1 which is plastically deformed can be flattened in the contact area, so that the appearance quality is improved. And, compared to stage three, the current density between the first electrode 1 and the first test plate 3 is greatly reduced in stage four, and then the temperature is reduced accordingly, the melting of the plating layer on the surface of the first test plate 3 in contact with the first working area 12 and the plastic deformation of the first test plate 3 are suppressed, the damage to the surface of the first test plate 3 is reduced or avoided, and the indentation is limited to the area of the convex working area 11.

In the feasible range, the smaller the diameter and the smaller the curvature radius of the convex working area 11, the more suitable the test plate welding with the larger plate thickness ratio is (the plate thickness ratio refers to the ratio of the total thickness of the plates to be welded to the thickness of the first layer of thin plate); the larger the diameter and the larger the radius of curvature of the first working area 12, the better the appearance quality of the pressed first test panel 3.

Based on the same inventive concept, the present embodiment provides a resistance spot welding method as shown in fig. 9, the method including:

step S91, placing a first test plate 3 and a second test plate 4 between a first electrode 1 and a second electrode 2, so that the first test plate 3 is in contact with the convex working area 11 of the first electrode 1, and the second test plate 4 is in contact with the second working area 21 of the second electrode 2, wherein the thickness of the first test plate 3 is smaller than that of the second test plate 4;

step S92, applying pressure and welding current to the first electrode 1 and the second electrode 2 to form a target nugget between the first test plate 3 and the second test plate 4.

In executing step S92, in order to face a difference between the two cases of "no intermediate test panel 5 between the first test panel 3 and the second test panel 4" and "intermediate test panel 5 between the first test panel 3 and the second test panel 4", step S92 is now explained below for the two cases, respectively.

[ No intermediate test board 5 ]

When there is no intermediate test panel 5 between the first test panel 3 and the second test panel 4, the step S92 may specifically include the step S101.

Step S101, applying pressure and welding current to the first electrode 1 and the second electrode 2 to form a target nugget (e.g., nugget 6 in fig. 4 and 5) between the contact surfaces of the first test board 3 and the second test board 4.

Step S101 corresponds to the process of [ stage one ] above. In phase one, the applied pressure N is small, the welding current I is large, the execution time period T is short, and the target nugget (e.g., the nugget 6 in fig. 4 and 5) can be quickly formed between the first test plate 3 and the second test plate 4. In this process, the greater the contact resistance between the first test plate 3 and the second test plate 4, the more favorable the formation of nuggets therebetween. In addition, the larger the welding current I and the shorter the execution time T, the more advantageous the heat loss due to the heat dissipation of the first electrode 1 is, and the more advantageous the nucleation between the first test plate 3 and the second test plate 4 is.

When there is no intermediate test panel 5 between the first test panel 3 and the second test panel 4, the step S101 may specifically include the steps S111 and S112.

In step S111, a first pressure N1 and a first welding current I1 are applied to the first electrode 1 and the second electrode 2, so that a first nugget (e.g., nugget 6 in fig. 4 and 5) is formed between the contact surfaces of the first test board 3 and the second test board 4.

Step S112, applying a second pressure N2 and a second welding current I2 to the first electrode 1 and the second electrode 2, so that a second nugget (such as the nugget 7 in fig. 5) is formed in a middle region of the total thickness of the first test board 3 and the second test board 4, wherein the target nugget includes the first nugget and the second nugget.

Steps S111 to S112 correspond to the processes of [ stage one ] and [ stage two ] described above. In the first phase, the applied first pressure N1 is small, the first welding current I1 is large, the execution time period T1 is short, and the first nugget can be quickly formed between the first test plate 3 and the second test plate 4. In the second stage, the applied second pressure N2 is larger, the second welding current I2 is smaller, and the execution time duration T2 is longer, so that the growth speed of a weld nugget formed between the first test plate 3 and the second test plate 4 can be slowed down, the welding stability of the first test plate 3 and the second test plate 4 is improved, and the occurrence of welding spatter is avoided. Further, in step S112, near the middle position of the total thickness of the first test board 3 and the second test board 4, a second nugget may be formed, and as the second nugget grows, the first nugget and the second nugget may be joined together to form a target nugget between the first test board 3 and the second test board 4.

Step S112 may be replaced with step S122 below.

Step S122, applying a third pressure N3 and a third welding current I3 to the first electrode 1 and the second electrode 2, so as to form a third nugget (such as the nugget 6 in fig. 4 and 5) between the contact surfaces of the first test board 3 and the second test board 4;

step S123, applying a fourth pressure N4 and a fourth welding current I4 to the first electrode 1 and the second electrode 2, so as to make the third nugget grow continuously and grow toward the second test board 4, and using the grown third nugget as a target nugget (e.g., the nugget formed by the nugget 6 and the nugget 7 in fig. 5).

In phase one, the third applied pressure N3 is small, the third welding current I3 is large, the execution time period T3 is short, and the third nugget can be quickly formed between the first test plate 3 and the second test plate 4. In the second stage, the applied fourth pressure N4 is larger, the fourth welding current I4 is smaller, and the execution time duration T4 is longer, so that the growth speed of a weld nugget formed between the first test plate 3 and the second test plate 4 can be slowed down, the welding stability of the first test plate 3 and the second test plate 4 is improved, and the occurrence of welding spatter is avoided. Further, in the second stage, the nugget is not separately formed at a position near the middle of the total thickness of the first test board 3 and the second test board 4, but is grown in the direction of the second test board 4 on the basis of the third nugget, and finally the target nugget between the first test board 3 and the second test board 4 is formed.

[ with intermediate test board 5 ]

When the intermediate test panel 5 is included between the first test panel 3 and the second test panel 4, the step S102 specifically includes a step S131 and a step S132.

In step S131, a fifth pressure N5 and a fifth welding current I5 are applied to the first electrode 1 and the second electrode 2, so that a fourth nugget (e.g., nugget 6 in fig. 7 and 8) is formed between the contact surfaces of the first test board 3 and the intermediate test board 5.

Step S132, applying a sixth pressure N6 and a sixth welding current I6 to the first electrode 1 and the second electrode 2, so as to form a fifth nugget (e.g., nugget 7 in fig. 8) between the contact surfaces of the intermediate test board 5 and the second test board 4, where the target nugget includes the fourth nugget and the fifth nugget.

Steps S131 to S132 correspond to the processes of [ stage three ] and [ stage four ] described above.

In phase three, the applied fifth pressure N5 is small, the fifth welding current I5 is large, and the execution time period T5 is short. On one hand, because the nugget is small at the moment, the welding is carried out in a short time by adopting large current, and no splashing occurs; on the other hand, the time is short, so that the electrode heat dissipation is avoided, the welding temperature of the electrode is guaranteed to a certain degree, and a fourth weld nugget is formed between the first test plate 3 and the middle test plate 5 quickly. In the fourth stage, the applied sixth pressure N6 is larger, the sixth welding current I6 is smaller, and the execution time period T6 is longer, so that the growth speed of the fourth nugget formed between the first test plate 3 and the middle test plate 5 can be slowed down, and welding spatter can be avoided. Meanwhile, a fifth welding core is formed between the middle test plate 5 and the second test plate 4, so that the purpose of welding the first test plate 3, the middle test plate 5 and the second test plate 4 is achieved.

In summary, the resistance spot welding method provided in this embodiment can depend on the characteristic that the current density of the protruding working area 11 is large, the position of the nugget nucleation is shifted to the interface position between the first test plate 3 and the second test plate 4 (the first test plate 3 and the second test plate 4 have different thicknesses, and the former is smaller than the latter), and the test plates with different thicknesses can be efficiently welded, compared with the electrode shown in fig. 1, the resistance spot welding device provided in this embodiment greatly improves the connection strength between the two test plates with different thicknesses, and also greatly reduces the difficulty of welding; meanwhile, the first working area 12 can be used for flattening the molten coating extruded from the protruding working area 11 and the first test plate 3 subjected to plastic deformation, so that the appearance of the first test plate 3 is improved, the appearance does not need to be improved at the later stage, and the cost is saved.

In order to better understand the resistance spot welding apparatus and the resistance spot welding method provided above, the following specific examples are now provided for explanation.

The material of the first electrode 1 and the second electrode 2 may be chromium zirconium copper. The diameter d11 of the first electrode body 14 is 20 mm. The first cooling tank 15 contains cooling water, and the flow rate of the cooling water is 4L/min. The first transition zone 13 is spherical. The diameter d141 of the convex working area 11 is 4mm, and the radius R141 of the curved surface of the convex working area 11 is 10 mm. The diameter d142 of the first working area 12 is the diameter d14 of the first working area 12, d142 ═ d14 ═ 8 mm; the radius of curvature R142 of the first working area 12 is 100 mm.

The diameter d21 of the second electrode body 23 is 20 mm. The second cooling tank 24 is filled with cooling water, and the flow rate of the cooling water is 4L/min. The second transition region 22 is spherical. The diameter d24 of the second working area 21 is 6mm, and the radius of curvature R24 of the second working area 21 is 50 mm.

The first test panel 3 was DX56D + Z (representing a type of panel having a surface of 50 g/m) with a thickness of 0.6mm²The second test piece 4 was 1.8mm DP980+ Z thick, and the intermediate test piece 5 was 1.8mm DP980+ Z thick, and the thickness ratio was calculated to be (0.6+1.8+1.8)/0.6 to 7.

The welding power supply can be a power frequency power supply or a medium frequency power supply. In this embodiment, the welding power supply is a 1000Hz intermediate frequency power supply.

The diameter of the first working area 12 is larger than or equal to that of the second working area 21; the radius of curvature of the first working area 12 is greater than the radius of curvature of the second working area 21; the diameter of the convex working area 11 is smaller than that of the second working area 21; the radius of curvature of the convex working area 11 is smaller than the radius of curvature of the second working area 21.

In this embodiment, the welding method according to the above apparatus includes the steps of:

s1: placing a part to be welded of a material combination (comprising a first test plate 3, an intermediate test plate 5 and a second test plate 4) between a first electrode 1 and a second electrode 2; in the solder material combination, 0.6mm DX56D + Z as the first test piece 3 is located on the first electrode 1 side, 1.8mm DP980+ Z as the second test piece 4 is located on the second electrode 2 side, and 1.8mm DP980+ Z as the intermediate test piece 5 is located between the first test piece 3 and the second test piece 4.

S2: the first electrode 1 and the second electrode 2 are moved so that the convex working areas 11 are in contact with the first test plate 3 and the second working areas 21 are in contact with the second test plate 4.

S3: the welding process is divided into two stages:

the first stage is as follows: applying a pressure N ' of 1.5kN, an I ' of 9kA and a welding time T ' of 0.06S between the first electrode 1 and the second electrode 2 to complete the first stage welding, and forming a weld nugget 6 as shown in fig. 7 and 8 on the contact surface between the first test board 3 and the intermediate test board 5;

in the second stage, a pressure N ″ -3.5 kN, an I ″ -8 kA, and a welding time T ″ -0.4S are applied between the first electrode 1 and the second electrode 2, and the second stage welding is completed, so that a nugget 7 as shown in fig. 7 and 8 is formed inside the material combination 3.

After the end of the second stage welding, the electrode pressure N ″, 3.5kN was maintained for 0.2S. In actual operation, no weld spatter occurs during the entire welding process at stage S3.

S4: and (5) opening the first electrode 1 and the second electrode 2, and finishing welding.

In the present embodiment, the parameters satisfy:

the pressure N 'in the first stage is less than or equal to the pressure N' in the second stage;

the first stage welding time T '< the second stage welding time T'.

The appearance inspection is carried out on the welded material combination of the embodiment, the indentation of the surface of the welding spot meets the requirement of indentation depth, namely the indentation depth is less than 20% of the plate thickness, and the surface quality of the first test plate 3 is obviously better than that of the second test plate 4: an indentation (i.e. a small pit caused by the raised working area 11) with the diameter of about 4mm and the depth of 0.1mm is arranged at the center of a welding spot on the surface of the first test plate 3; on the surface of the second test plate 4, there are indentations with a diameter of about 7mm and a depth of 0.2mm at the welding points.

The cross tensile test was performed on the material combination after welding in this example, and the results were:

the button between the first test plate 3 and the middle test plate 5 is broken, the weld nugget diameter is 4.5mm, the requirement of more than 4 v t (t is the thickness of the thin plate in two adjacent plates) is met, and 4 v t between the first test plate 3 and the middle test plate 5 is 4 v 0.6 and 3.1 mm;

the button between the second test plate 4 and the middle test plate 5 is broken, the weld nugget diameter is 6.5mm, the requirement of more than 4 v t (t is the thickness of the thin plate in two adjacent plates) is met, and 4 v t between the second test plate 4 and the middle test plate 5 is 4 v 1.8 and 5.4 mm.

The welding process using the electrode shown in fig. 1 is as follows:

the parameters of the upper electrode and the lower electrode are the same as those of the second electrode 2 provided in the present embodiment; the material combinations are the same as those provided above in this example.

Welding in a single pulse mode: the welding pressure is adjusted between 1.5kN and 4.0kN, and the welding current is adjusted between 6 kA and 10kA, so that the connection between the materials of the material combination cannot be realized. The welding current was increased further to 13kA, and although the connection between the materials of the material combination was finally achieved, the weld spatter was severe. The diameter of the nugget between the first test plate 3 and the middle test plate 5 is only 2.5mm, and the diameter of the nugget between the second test plate 4 and the middle test plate 5 is 7.0 mm. The surface quality of the welding spot is poor, yellow copper electrode materials are adhered, and the indentation depth is more than 0.3 mm.

It can be seen from the above specific examples that the resistance spot welding device and the method provided by the embodiment can greatly reduce the difficulty of welding the test plate, improve the appearance quality of the surface of the test plate, and reduce the cost.

Since the electronic device described in this embodiment is an electronic device used for implementing the method for processing information in this embodiment, a person skilled in the art can understand the specific implementation manner of the electronic device of this embodiment and various variations thereof based on the method for processing information described in this embodiment, and therefore, how to implement the method in this embodiment by the electronic device is not described in detail here. Electronic devices used by those skilled in the art to implement the method for processing information in the embodiments of the present application are all within the scope of the present application.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.