阅读说明：本技术 弹簧片和用于制造弹簧片的方法 (Spring leaf and method for producing a spring leaf ) 是由 J·扎姆博格 于 2018-10-16 设计创作，主要内容包括：本发明涉及一种用于制造用于片弹簧的弹簧片(2)的方法,所述片弹簧尤其是抛物线弹簧或悬挂弹簧,其中,所述弹簧片(2)具有两个端部区域、中间区域、在使用状态中受拉应力的上侧、在使用状态中受压应力的下侧(1),在下侧(1)中制入至少一个孔(3),在围绕孔(3)的区域中对下侧(1)进行喷射。(The invention relates to a method for producing a leaf spring (2) for a leaf spring, in particular a parabolic spring or a suspension spring, wherein the leaf spring (2) has two end regions, a middle region, an upper side which is under tensile stress in the use state, and a lower side (1) which is under compressive stress in the use state, wherein at least holes (3) are made in the lower side (1), and wherein the lower side (1) is sprayed in a region surrounding the holes (3).)

1. Method for producing a leaf spring (2) for a leaf spring, in particular a parabolic spring or a suspension spring, wherein the leaf spring (2) has two end regions, an intermediate region, an upper side which is under tensile stress in the use state, and a lower side (1) which is under compressive stress in the use state, and wherein at least holes (3) are made in the lower side (1), characterized in that the lower side (1) is sprayed in a region surrounding the holes (3).

2. A method as claimed in claim 1, characterized in that the underside (1) is locally sprayed in a region surrounding the hole (3).

3. A method as claimed in claim 1, characterized in that the underside (1) is shot-peened in the area surrounding the hole (3).

4., method according to claims 1 to 3, characterized in that the spray (8) is applied through a spray nozzle (7), wherein the spray nozzle (7) and the area of the hole (3) are aligned with each other.

5. Method according to claim 4, characterized in that the injection nozzle (7) is moved towards the spring plate (2) and/or the spring plate (2) is moved towards the injection nozzle (7).

6., according to claims 1 to 5, characterized in that the injection is carried out in an area surrounding the aperture (3) so that the distance from the aperture (3) to the transition (4) between the injected and non-injected surfaces of the underside (1) lies in the range of about 5cm or 4cm or 3cm or 2cm or 1 cm.

7., the method according to claims 1 to 6, characterized in that through-holes or blind-holes are made as the holes (3).

8. A method as claimed in claim 7, characterized in that a clamping area with a central bore running through is formed in the central area and the area surrounding the central bore is sprayed.

9., the method according to claims 1 to 8, characterized in that the spring plate (2) is manufactured from flat bar steel, in particular spring steel.

10., according to claims 1 to 9, characterized in that the spring plate (2) is hot-formed, in particular rolled, and then tempered in that the upper side of the spring plate (2) is sprayed, in particular with the spring plate (2) pre-tensioned, and that the lower side (1) of the spring plate (2) is sprayed in the area around the hole (3) after the spraying of the upper side of the spring plate (2).

11. Leaf spring for a leaf spring, in particular a parabolic spring or a suspension spring, wherein the leaf spring (2) has two end regions, an intermediate region, an upper side which is under tensile stress in the use state, and a lower side (1) which is under compressive stress in the use state, and wherein the lower side (1) has at least holes (3), characterized in that the lower side (1) is locally sprayed in a region surrounding the holes (3).

12. A spring plate according to claim 11, characterized in that the underside (1) is shot-peened in the area around the hole (3).

13. The spring plate according to claim 11 or 12, characterized in that the distance from the hole (3) to the transition (4) between the sprayed and the non-sprayed surface of the underside (1) is in the range of about 5cm or 4cm or 3cm or 2cm or 1 cm.

14., the spring plate of any of claims 11 to 13, wherein the holes (3) are through holes or blind holes.

15. The spring plate according to claim 14, characterized in that a clamping area with a central bore therethrough is formed in the central area and that the area surrounding the central bore is sprayed.

16. the spring plate of any of claims 11 to 15, wherein the spring plate is made of flat bar steel, in particular spring steel.

Technical Field

The invention relates to a method for producing a leaf spring for a leaf spring, in particular a parabolic spring or a suspension spring, wherein the leaf spring has two end regions, an intermediate region, an upper side which is under tensile stress in the use state, and a lower side which is under compressive stress in the use state, and wherein at least holes are made in the lower side.

The invention further relates to leaf springs for leaf springs, in particular parabolic springs or suspension springs, wherein the leaf springs have two end regions, an intermediate region, an upper side which is under tensile stress in the use state, and a lower side which is under compressive stress in the use state, and wherein the lower side has at least holes.

Background

The demand for motor vehicles is to reduce the weight of the individual components, and is to subject the individual components to increasingly high mechanical loads, for example due to increased motor power.

The leaf springs comprise a single spring leaf or a plurality of spring leaves, wherein each spring leaf has two end sections and an intermediate section between the two end sections, a clamping region is provided in the intermediate section, in which clamping region the leaf spring is connected to the axle or axle pin of the vehicle via a connecting region, in particular via or more U-shaped pins or profiles which surround the leaf spring in the clamping region.

If the leaf spring has a plurality of leaf springs arranged one above the other, these leaf springs are often connected to one another in the clamping region, in particular by a pin which passes through a central through-hole (furthermore: an intermediate hole) in the clamping region of each leaf spring, wherein the leaf springs either bear directly against one another or an intermediate element, such as an intermediate metal plate, is arranged or sandwiched between the leaf springs.

The base spring leaf may have at least end sections provided with through-openings through which connecting means for connecting the leaf spring to a vehicle component, in particular to an axle, can be guided.

The leaf spring of the multi-leaf spring can have further through-openings and/or blind openings on its underside, the single leaf spring can also have through-openings and/or blind openings on its underside, for example provided in at least end sections, through which through-openings the leaf spring can be guided with a vehicle component, in particular with a connecting means for a shaft connection.

A known problem in leaf springs is that, when the mechanical stress rises, the leaf spring can break in the region of the holes. The problem of fracture of the central bore is particularly to be considered in this connection.

The center hole fracture forms a generally known and undesirable fracture characteristic in the leaf spring, and in general, the center hole fracture starts from the underside of the spring leaf which is stressed in compression in the use state.

The cause of the fracture of the intermediate hole has hitherto not been clearly established. Hydrogen induced cracking (HAC) is generally considered in practice as the cause of mesopore fracture.

In order to avoid fracture of the central bore, it is known from CA2865630a1 to avoid hydrogen-induced cracking by locally heating the spring plate and then rapidly cooling it. This method is disadvantageous because it is technically complex and heating and cooling constitute a high and expensive energy expenditure. Furthermore, this heating can only take place before the injection treatment of the upper side of the spring plate, since the heating of the spring plate after the injection treatment should no longer take place, since the heating has an adverse effect on the surface properties of the spring plate.

In order to avoid fracture of the central opening, it is also known to chamfer the edges of the central opening on the underside of the spring plate and to provide a relatively soft steel central layer (relative to the material of the spring plate) between the spring plates and on the upper side of the spring plate.

Disclosure of Invention

The object of the present invention is to provide spring plates for leaf springs, with which the risk of a hole breaking, in particular the risk of a central hole breaking, is reduced while avoiding the disadvantages of the prior art.

It is known here that the spring leaf, on its upper side which is under tensile stress in the use state, is tempered after the rolling process and is further treated , in particular shot peening or stress peening, in order to optimize the stress distribution, the lower side which is under compressive stress in the use state usually not being peened but being held in the material state after the rolling process and tempering.

It has surprisingly been found that the cause of the center hole fracture can be a tensile stress on the side of the spring leaf which is stressed in the use state by means of a stress injection on the side of the spring leaf which is stressed in tension in the use state, the tensile stress being present on the side of the spring leaf which is stressed in compression in the use state after the stress injection, i.e. after the spring leaf has been relieved again.

The upper side of the spring plate is treated , in particular with a stress jet, after the rolling process in order to optimize the stress distribution, while the lower side is not treated , so that tensile stresses may remain on the lower side in this material state.

In this material state, too high a stress may occur on the edge of the hole in the use state of the leaf spring, when e.g. a plurality of pieces of spring are screwed together, a force transmission occurs thereby and thus a stress transfer from the bolt head onto the underside of the leaf spring.

Furthermore, tensile stresses in the region near the surface may promote hydrogen induced cracking (HAC), thereby in turn increasing the risk of intermediate pore fracture.

The invention makes use of these new recognitions in such a way that, according to the invention, the underside of the spring plate is sprayed in the region surrounding the hole. This results in slight compressive stresses which are unexpectedly superimposed on the tensile stresses which are a cause of the center hole fracture and increase the local life of the spring plate. As a result, the risk of hole fractures is significantly reduced, wherein the expenditure of process technology and the energy and production costs are not appreciably increased during the production of the spring leaf and additional components which lead to further costs and constitute additional weight do not have to be installed.

Particularly advantageously, hydrogen-induced cracking is also avoided, wherein, contrary to the method according to CA2865630a1, no tensile stress is present on the underside of the spring leaf.

The spring plate is made of a profiled bar. The profiled bar is cut, heated and subjected to a forming process, in particular a rolling and stamping process, so that the profiled bar is brought into the desired shape of the spring leaf. After forming, a tempering measure is performed. During the shaping of the profiled bar, a semifinished product is present. When all the processing steps, i.e. also including the tempering after the forming process has taken place, have ended, there is a finished spring leaf as the final product.

It is within the scope of the invention, however, to refer to it as a leaf spring during the forming process. It should therefore be clear that making a hole in the underside and spraying the underside in the region of the hole are method steps for characterizing the spring leaf which is present as a finished end product after all processing steps have been completed.

However, since this results in a process cost of and an adverse effect on the capacity of the injection device, it is provided in particularly preferred embodiments that the underside is injected locally in the region around the bore, i.e. only in the region around the bore, but not in the region without a bore, it is possible in further preferred embodiments of the invention to shot the underside in the region around the bore.

For example, a spray having a particle size of 0.4 to 1.2mm may be used. It is particularly economical to reuse already used spray, for example spray for spraying the upper side of the spring plate.

Within the scope of the invention, the spray can be applied by means of a spray nozzle, wherein the spray nozzle and the region of the bore are aligned with one another. For this purpose, the nozzle is moved toward the spring plate and/or the spring plate is moved toward the nozzle.

For example, a robot in an automatic spray device may turn the spring plate over and hold it for a few seconds with the corresponding hole in the underside towards the spray nozzle. In the case of a manual spray device, the spring plate may be placed on the conveyor belt after spraying on the upper side. The conveyor belt moves the spring plate past the spray nozzles.

It is preferred within the scope of the invention that the area surrounding the hole is sprayed such that the distance from the hole to the transition between the sprayed and the non-sprayed surface on the underside lies in the range of about 5cm or 4cm or 3cm or 2cm or 1 cm.

Rather, the transition between the unexprayed region and the sprayed region is gradually completed in a scatter region defined by .

Within the scope of the invention, through-holes or blind holes can be made as holes. A plurality of holes may be provided, wherein any combination of through-holes or blind holes is conceivable.

In the case of the particularly preferred embodiments of the invention, it can be provided that a clamping region with a through-opening intermediate opening is formed in the intermediate region and that the region surrounding the intermediate opening is sprayed.

Within the scope of the invention, it is provided that the spring plate is made of flat bar steel, in particular spring steel.

particularly preferred embodiments of the invention may be constructed as follows:

the spring plate is hot-formed, in particular rolled, and then conditioned by spraying the upper side of the spring plate, in particular with the spring plate pre-tensioned, and after spraying the upper side of the spring plate, in particular with the spring plate pre-tensioned, spraying the lower side of the spring plate in the region around the hole. The spraying of the underside of the spring plate in the area around the hole may take place immediately after the spraying of the upper side of the spring plate, or still other processes may take place between the spraying of the upper side and the spraying of the underside.

Drawings

In the figure:

FIG. 1 shows the region of the underside of the spring plate in the region of the hole, and

fig. 2 shows a block diagram of embodiments with a method sequence according to the invention.

Detailed Description

Fig. 1 shows the region of the underside 1 of a spring plate 2 for a leaf spring, in which a bore 3 is made. The leaf spring may be, for example, a parabolic spring or a suspension spring. The holes 3 may be through holes or blind holes. The opening 3 can be a central opening provided in the clamping region or in other regions of the spring plate 2, for example in the end regions. The underside 1 of the spring plate 2 is stressed in compression in the use state of the plate spring.

The spring plate 2 is preferably made of flat bar steel, in particular spring steel, the underside 1 of the spring plate 2 is locally sprayed, in particular shot-blasted, in the region around the hole 3, the distance from the hole 3 to the transition 4 between the sprayed and the non-sprayed surface of the underside 1 is in the range of a few centimeters, during spraying an -th region 5 is produced around the hole, which -th region is sprayed uniformly, and a second region 6 adjoining the -th region is produced, in which the transition between the non-sprayed region and the sprayed region is gradually completed in a spreading region of .

The spraying can be done by means of a spray nozzle 7, which applies a spray 8 onto the underside 1, wherein the spray nozzle 7 and the area of the hole 3 are aligned with each other.

An exemplary method sequence for producing a spring plate 2 according to the invention is shown in block diagram form in fig. 2, wherein the individual numbered blocks may comprise or more method steps.

In block 9, for example, the profiled rod can be cut to the desired length and heated.

In block 10, a heat treatment and hot forming process can be carried out, in particular, the heated profiled rod can be rolled and optionally cut , wherein at least bores 3 are made in the underside 1 of the spring plate 2 to be produced, in block 10, in particular, intermediate bores can be made in the clamping region, alternatively or additionally at least longitudinal ends of the spring plate 2 can be worked in that at least end sections are formed as means for connecting the spring plate to a vehicle frame or to a connecting part of a wheel suspension, in particular as a coil spring eye.

Other machining operations may be performed in block 11. The processes for bending, tempering, hardening and tempering of the spring piece 2 may be performed. Also, the injection may be performed on the upper side of the leaf spring 2, in particular with the leaf spring 2 pre-tensioned.

Blocks 9 to 11 comprise method steps known from the prior art.

In block 12, the method step proposed according to the invention is carried out, wherein the underside 1 is sprayed, in particular locally sprayed, preferably shot-blasted, in the region of the area openings 3.

Other processes may be performed after block 12 until the leaf spring is completed, wherein the leaf spring may have leaf springs 2 or two or more leaf springs 2.

If the spring eye is rolled out, the eye support can be pressed in, for example. The spring plate 2 may be painted, for example. The leaf springs can be placed, tested and secured.

The injection of the underside of the spring plate 2 described in connection with block 12 may be performed directly after the stress injection of the upper side of the spring plate 2 and further processing, such as placing, may be performed on the underside between the injection of the upper side and the injection of the underside.