阅读说明：本技术 一种大型塑料部件的焊接工艺 (Welding process of large plastic part ) 是由 刘润强 刘楚佳 李泽轩 于 2021-08-23 设计创作，主要内容包括：本发明公开了一种大型塑料部件的焊接工艺,属于塑料焊接技术领域。该焊接工艺是采用与待焊接塑料部件相同材质的热熔板带,并将其置于两个或多个塑料部件待焊接面之间,经过加压保压、冷却定型,将两个或多个塑料部件焊接为一体。采用该工艺可焊接具有较大焊接面积复杂大型塑料部件,成型部件强度大、焊接效率高。(The invention discloses a welding process of a large plastic part, and belongs to the technical field of plastic welding. The welding process adopts a hot melting plate strip which is made of the same material as the plastic parts to be welded, and the hot melting plate strip is placed between the surfaces to be welded of two or more plastic parts, and the two or more plastic parts are welded into a whole through pressurization, pressure maintaining, cooling and shaping. The process can be used for welding large plastic parts with large welding area and complexity, and the formed parts have high strength and high welding efficiency.)

1. A welding process of large plastic parts is characterized in that: the welding process is characterized in that a hot melting plate strip which is made of the same material as the plastic parts to be welded is arranged between the surfaces to be welded of two or more plastic parts, and the two or more plastic parts are welded into a whole through pressurization, pressure maintaining, cooling and shaping.

2. A process for welding large plastic parts according to claim 1, characterized in that: the welding process comprises the following steps:

(1) placing a plastic part to be welded into a welding workbench;

(2) pretreating the welding surface of the plastic part to be welded, including cleaning treatment and preheating treatment;

(3) adopting a single-screw extruder to perform hot melting extrusion on a premixed hot melting plate strip raw material with the same material as a plastic part to be welded, forming a continuous hot melting plate strip with certain width and thickness through a die, and flexibly setting the width and the thickness of the hot melting plate strip according to a surface to be welded;

(4) and (3) hot melting welding: and placing the hot melt plate strip between two or more plastic parts to be welded, wherein the hot melt plate strip is required to be insulated at the temperature of 200-280 ℃ before being placed in a welding line and after being placed in the welding line until being pressurized and cooled, the pressure is 0.2-0.5MPa, and the pressure maintaining time is 2 hours.

3. The plastic part welding process of claim 1, wherein: the plastic part is made of a high-molecular thermoplastic material: one or a blended material of thermoplastic materials such as polyethylene pe, polypropylene pp, polyamide pa, acrylonitrile butadiene styrene copolymer abs, acrylonitrile styrene acrylic rubber copolymer asa, polycarbonate pc, polyvinyl chloride pvc (hereinafter referred to as pe, pp, pa, abs, asa, pc and pvc) and the like, wherein the plastic material with the content of more than 70 percent is subjected to hot melting extrusion molding to obtain a plate or a plastic part made of section bars with different section shapes, or the plastic plate or the section bars; the plastic raw material comprises a high-molecular thermoplastic material, an auxiliary agent and a reinforcing material, wherein: the content of the high-molecular thermoplastic materials pe, pp, pa, abs, asa, pc and pvc is 70-95 wt.%, and the balance is auxiliary agents or reinforcing materials; the content of one or more of the additives is 5-10 wt.% of conventional functional additives and processing additives, the content of the reinforced materials is 0-20 wt.% of glass fibers or carbon fibers, and the high polymer thermoplastic materials are one or a blending material of pe, pp, pa, abs, asa, pc and pvc.

4. The plastic part welding process of claim 1, wherein: in the step (1), the welding workbench is a welding operation platform which is made of steel, aluminum alloy, plates or profiles and has the functions of shaping, polishing, preheating, pressurizing, pressure maintaining and cooling and shaping the plastic parts to be welded, the welding workbench is matched with an extruder to complete the welding operation of large plastic parts, and the size and the function of the welding workbench are matched with the plastic parts to be welded.

5. A process for welding plastic parts according to claim 1, characterized in that: in the step (2), the cleaning treatment refers to cutting and polishing the surface to be welded of the plastic part to remove an oxide layer; the preheating treatment preheats the surfaces to be welded of the plastic parts to 180-260 ℃ before welding.

6. A process for welding plastic parts according to claim 1, characterized in that: in the step (3), the specific process of extruding the hot-melt plate strip comprises the following steps (a) to (b):

(a) fully mixing and drying hot-melt plate strip raw materials with the same material as plastic parts to be welded;

(b) extruding a hot-melt plate strip by adopting a single-screw extruder, wherein the melt temperature of the hot-melt plate strip is set to be 200-280 ℃; a small extruder or a large extruder can be adopted according to the welding amount; the hot-melt strip welding machine can extrude a narrow single hot-melt strip and also can extrude a wide hot-melt strip, the extruded wide hot-melt strip is cut into a plurality of hot-melt strips through a machine head splitting machine, and the hot-melt strip is used for welding a plurality of plastic components at the same time, so that the welding efficiency is improved.

7. The plastic part welding process of claim 6, wherein: in the step (3), the single-screw extruder is installed near the welding workbench, so that welding operation of the hot-melt plate strip is facilitated, the extruder can be fixedly installed or can be installed on a gantry type frame body, the gantry type frame body is installed on two parallel rails, X, Y, Z movement in three directions can be achieved through numerical control of the extruder, the angle of a mouth-shaped die is adjusted through the hot-melt plate strip extruded by the extruder, the hot-melt plate strip is conveniently placed between plastic components, and therefore automatic welding is achieved.

8. The process for welding plastic parts according to claim 7, characterized in that: in the hot-melt welding process in the step (4), after a single-screw extruder extrudes a wide hot-melt plate, the wide hot-melt plate is cut into a plurality of hot-melt plate strips with the sizes matched with the sizes of the welding openings of the plastic profiles through a cutting device, the hot-melt plate strips are placed between preheated plastic parts through a heat-preservation conveying device, a pressurizing and pressure-maintaining device is arranged between the plastic parts, and a welding workbench is provided with a hot air device.

9. The process for welding plastic parts according to claim 7, characterized in that: in the hot-melting welding process in the step (4), the ambient environment needs to be clean and dry, and the ambient temperature is not lower than 5 ℃.

Technical Field

The invention relates to the technical field of plastic welding, in particular to a welding process of a large plastic part.

Background

The high polymer thermoplastic material can be recycled, and the plastic product made of the high polymer thermoplastic material can replace wood, metal and glass fiber reinforced plastic products, and is increasingly valued in the industry due to the outstanding advantages of high safety, energy conservation, environmental protection, low maintenance cost and the like.

For some large plastic products needing welding forming, a plastic plate is generally cut into a required shape through a plate cutting machine and then is connected and formed through hot melting welding in different modes.

Such as: 1: when a hot plate is adopted to weld large-scale plastic parts, the difficulty in manufacturing the hot plate of the part with a complex welding surface is high, and the cost is high. 2: when large-scale plastic parts are welded by irradiation and hot air heating, the heating time is long, the efficiency is low, and the welding quality is poor. 3: the plastic extrusion gun shown in figure 1 is used for welding and forming. The extrusion amount of the welding gun is very small, the dead angles in the parts cannot be welded, pressurizing and pressure maintaining links are omitted, the welding quality cannot be guaranteed, the welding efficiency is extremely low, and the welding gun is not suitable for welding large plastic parts.

Disclosure of Invention

Aiming at the defects of the existing large plastic part during welding, the invention aims to provide the welding process of the large plastic part, and when the process is used for welding the large plastic part, the welding quality is high, the universality is strong, and the welding efficiency is high.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a welding technology for large plastic parts features that a hot-smelting plate band made of the same material as the plastic parts to be welded is used and is put between the surfaces to be welded of two or more plastic parts, and the two or more plastic parts are welded together by pressurizing, pressure-maintaining, cooling and shaping. The welding process comprises the following steps:

(1) placing a plastic part to be welded into a welding workbench;

(2) pretreating the welding surface of the plastic part to be welded, including cleaning treatment and preheating treatment;

(3) adopting a single-screw extruder to perform hot melting extrusion on a premixed hot melting plate strip raw material with the same material as a plastic part to be welded, forming a continuous hot melting plate strip with certain width and thickness through a die, and flexibly setting the width and the thickness of the hot melting plate strip according to a surface to be welded;

(4) and (3) hot melting welding: and (2) placing the hot-melt plate strip between two or more plastic parts to be welded, and before and after the hot-melt plate strip is placed in the welding line, keeping the temperature at 200-280 ℃ (set according to the material of the hot-melt plate strip) until the hot-melt plate strip is pressurized and cooled, wherein the pressure is 0.2-0.5MPa, and the pressure keeping time is 2 hours.

The plastic part is a plastic part made of a plate or sectional materials with different section shapes obtained by hot-melting and extrusion molding of a plastic raw material with the content of a high-molecular thermoplastic material being more than 70 percent, or is the plastic plate or the sectional materials; the plastic raw material comprises a high-molecular thermoplastic material, an auxiliary agent and a reinforcing material, wherein: the high polymer thermoplastic material is a pe material, a pp material, a pa material, an abs material, an asa material, a pc material, a pvc material or a blending material thereof, the content of the high polymer thermoplastic material is 70-95 wt%, the balance is an additive or a reinforcing material, the content of the additive is 5-10 wt% of one or more of conventional functional additives and processing additives, and the content of the reinforcing material is 0-20 wt% of glass fiber or carbon fiber.

In the step (1), the welding workbench is a welding operation platform which is made of steel, aluminum alloy, plates or profiles and has the functions of shaping, polishing, preheating, pressurizing, pressure maintaining and cooling and shaping the plastic parts to be welded, the welding workbench is matched with an extruder to complete the welding operation of large plastic parts, and the size and the function of the welding workbench are matched with the plastic parts to be welded.

In the step (2), the cleaning treatment refers to cutting and polishing the surface to be welded of the plastic part to remove an oxide layer; the preheating treatment preheats the surfaces to be welded of the plastic parts to 180-260 ℃ before welding.

In the step (3), the specific process of extruding the hot-melt plate strip comprises the following steps (a) to (b):

(a) fully mixing and drying hot-melt plate strip raw materials with the same material as plastic parts to be welded;

(b) extruding a hot-melt plate strip by adopting a single-screw extruder, wherein the melt temperature of the hot-melt plate strip is set to be 200-280 ℃ (the specific temperature is determined according to the material of the hot-melt plate strip); a small extruder or a large extruder can be adopted according to the welding amount; the hot-melt strip can be extruded to form a narrow hot-melt strip (such as 6-15mm in thickness and 50-400mm in width) or a wide hot-melt strip (such as 8-15mm in thickness and 500-1600mm in width), and the extruded wide hot-melt strip is cut into a plurality of hot-melt strips by a machine head splitting machine for simultaneously welding a plurality of plastic components, so that the welding efficiency is improved.

In the step (3), the single-screw extruder is installed near the welding workbench, so that welding operation of the hot-melt plate strip is facilitated, the extruder can be fixedly installed or can be installed on a gantry type frame body, the gantry type frame body is installed on two parallel rails, X, Y, Z movement in three directions can be achieved through numerical control of the extruder, the angle of a mouth-shaped die is adjusted through the hot-melt plate strip extruded by the extruder, the hot-melt plate strip is conveniently placed between plastic components, and therefore automatic welding is achieved.

In the hot-melt welding process in the step (4), after a single-screw extruder extrudes a wide hot-melt plate, the wide hot-melt plate is cut into a plurality of hot-melt plate strips with the sizes matched with the sizes of the welding openings of the plastic profiles through a cutting device, the hot-melt plate strips are placed between preheated plastic parts through a heat-preservation conveying device, a pressurizing and pressure-maintaining device is arranged between the plastic parts, and a welding workbench is provided with a hot air device.

In the hot-melting welding process in the step (4), the ambient environment needs to be clean and dry, and the ambient temperature is not lower than 5 ℃.

The invention has the following advantages and beneficial effects:

1. the welding of large plastic parts is carried out by extruding hot-melt plate belt with single screw extruder, cutting into hot-melt plate belt with various widths (or extruding single hot-melt plate belt with small extruder), matching size with welding surface of plastic parts to be welded, putting between two plastic parts, heating, pressurizing, pressure maintaining, cooling and welding. The mode has high welding quality, good universality and high welding efficiency.

2. Because the single-screw extruder is adopted to extrude the hot-melt plate strip, the extrusion amount of the welding flux is large, the temperature is stable, the plasticizing effect is good, and the welding effect on the welding part is good.

3. The hot-melt plate strip is easily arranged in the preheated welding seam, so that the welding method has good adaptability to welding surfaces with different shapes, strong universality and greatly reduced tool cost.

4. A large extruder is adopted to extrude a wide hot-melt plate strip to cut a plurality of narrow hot-melt plate strips with certain sizes, a plurality of plastic components can be welded at the same time, and the welding efficiency is greatly improved.

5. A large numerical control gantry type extruder can be adopted for large plastic parts, and the extruder is matched with a welding workbench to realize automatic welding.

Drawings

Fig. 1 shows a conventional welding gun for plastic sheets.

Fig. 2 shows the plastic profile structure used in example 1.

FIG. 3 shows the thermal fusion molding in example 1.

Fig. 4 is a schematic view of a thermal welding process.

Detailed Description

For a further understanding of the present invention, the following description is given in conjunction with the examples which are set forth to illustrate, but are not to be construed to limit the present invention, features and advantages.

Example 1:

the embodiment is a small-sized high polymer thermoplastic material ship adopting a plastic section module with the welding length less than 24m, a plurality of strip-shaped cavities are arranged in the plastic section module, and the strip-shaped cavities are arranged in parallel along the direction vertical to the section of the section. As shown in fig. 2, the plastic section module of this embodiment is a structure with strip-shaped cavities and two open ends, and the cross section is rectangular.

The process for preparing the high polymer thermoplastic material ship by using the plastic section module comprises the following steps:

(1) preparing a plastic section module:

plastic raw materials are prepared, the high polymer thermoplastic material in this example is high density polyethylene hdpe with a content of 95 wt.%, and the balance is conventional antioxidant, anti-ultraviolet agent, color master, lubricant, and the like.

The plastic raw materials are subjected to high-speed mixing and drying, single-screw extruder die extrusion and fixed vacuum type table cooling and shaping processes to extrude the plastic section with the cross section shape shown in figure 2.

(2) Pre-assembling a plastic section module:

the method comprises the steps of placing a cut plastic section module into a slipway, cutting and polishing a surface to be welded to remove an oxide layer, wherein the slipway is also a welding workbench and is a steel frame structure, the width and the height of the plastic section are determined, so that the slipway has good adaptability to ship shapes of different sizes, hydraulic, pneumatic and mechanical clamps can be adopted, the sections to be welded have a separation mode and a clamping mode under the action of the slipway and the clamps, the slipway is provided with a hot air heating system, the welding surface needs to be heated by hot air before being placed into a hot melt plate strip, the temperature of the hot air is 280-300 ℃, and the welding surface can also be heated by irradiation.

(3) And (3) hot-melting welding and forming:

as shown in fig. 4, the preassembled plastic section modules are subjected to hot melt welding by a gantry type numerical control extruder, a hot melt plate strip made of the same material as the plastic section modules is adopted and is placed between the surfaces to be welded of the two plastic section modules, pressurization, pressure maintaining and cooling are carried out, two or more plastic section modules are welded into a whole, and each plastic section module is provided with a part of different hull structures, wherein a keel, a hull and a deck are arranged, and the plurality of plastic section modules are welded and combined to form the complete small plastic ship. The specific process is as follows:

(a) a single hot-melt plate strip is extruded by a numerical control gantry type single-screw extruder, the melt temperature of the hot-melt plate strip is set to be 260 ℃, the extruded hot-melt plate strip can be conveniently placed between two welding surfaces by adjusting the angle of a mouth-shaped die as shown in figure 3.

(b) The shipway is located below the gantry frame body, the width of the gantry frame body is larger than that of the shipway, the moving length of the double-gantry is larger than that of the shipway, so that an extruded hot-melting plate strip is just fused between plastic section modules needing to be welded, the preheating temperature of the section modules needing to be preheated in advance is 240 ℃, the shipway is provided with a plastic section module preheating and pressurizing pressure maintaining device, and the extrusion port type is provided with a accompanied hot air system, wherein the hot air temperature is 280-300 ℃.

(c)120/33 extruder horizontal fixed mounting is on the platform of bow or stern one side intermediate position take the altitude, and portable slipway can remove in this platform below, and the extruder extrudes broad width hot melt board, cuts into the hot melt slab band of several and plastic material weld seam size adaptation through cutting the device, puts into it through the removal of heat preservation conveyor and slipway between the plastic material that preheats on the slipway, stops to keep warm before the pressurization, pressurize the cooling and stereotype and accomplish the welding. No matter which welding method is adopted, the environment needs to be clean and dry, the environment temperature is not lower than 5 ℃, the part needing to be welded needs to be cut and polished in advance to remove an oxide layer, the welding pressure is 0.2-0.5mpa, and the pressure maintaining time is 2 hours.