TWI761736B - How to join and cool sheet parts - Google Patents

Abstract

A method for joining and cooling a sheet metal, comprising: providing a first metal sheet and a second metal sheet The melting point of the first metal sheet is higher than the minimum heating softening temperature of the second metal sheet; stack the first and second metal sheets on the die, heat the laminated sheet to the first temperature and stop heating, the first temperature is the sheet metal softening temperature of the first metal sheet; drive the self-piercing rivets into the laminated sheet to join the first and second metal sheets; cool the laminated sheet to the quenching temperature relative to the first metal sheet the second temperature; open the mold and take out the laminated sheet.

Description

How to join and cool sheet parts

The invention relates to a method for joining and cooling sheet parts, in particular to a method for heating a workpiece to soften before punching a self-piercing rivet, and performing in-mold quenching after the rivet is punched in.

In many fields (such as transportation), lightweighting is always an issue that must be considered, and both aluminum alloys and advanced high-strength steels are important materials for lightweight components, and dissimilar metals such as steel/aluminum have complementary effects. , By introducing low-density materials such as aluminum and magnesium composite materials into the all-steel body (composite body), it has become the trend of lightweighting of the global automobile body. Therefore, the technical field of car body manufacturing is a major challenge for dissimilar metal joining technology.

For mechanical joining methods, such as self-piercing riveting (Self-Pierce Riveting) is a high-strength mechanical joining, multi-layer materials are connected by hard rivets, no need to drill holes in the sheet metal in advance, and a small sound volume is generated during construction. And there is no need for any heat to enter the part during bonding. The rivet penetrates the upper material by applying pressure through the equipment, and at the same time, the rivet is expanded and deformed by the lower supporting die to achieve the mechanical joint effect. Since the lower material is not penetrated by the rivet, the sealing of the joint surface is also improved. Since self-piercing riveting does not require melting and has no heat affected zone, it has higher fatigue strength than traditional resistance welding, and the quality of the joint is good and can be automated, so it is suitable for dissimilar metal joining in vehicles. However, when the self-piercing riveting method is used for welding high-strength materials such as aluminum steel and high-strength steel, if the material has a tensile strength If the degree is greater than 680Mpa, the existing self-piercing riveting equipment is difficult to penetrate, and it is necessary to spend a lot of money to upgrade the existing equipment to be able to penetrate.

Japanese Patent Laid-Open No. 2016-055291 discloses a joining technology that applies self-piercing riveting and high-frequency heating to a plurality of resin parts. The joining device is formed by driving self-piercing rivets to a plurality of resin pieces arranged on a mold by means of a punch. The joining device includes: a mold, which supports the resin member and the legs of the self-piercing rivet; a mold supporter, which is used to support the mold and is formed of an insulator; a high-frequency electromagnetic induction coil, which is arranged in the mold support member; The clamp is used to fix the resin piece on the mold and is formed of an insulator; the high-frequency electromagnetic induction coil is wound around the front clamp; and the punch is used to drive the self-piercing rivet and is formed of the insulator. The self-piercing rivets are preheated by a high-frequency electromagnetic induction coil, a plurality of resin parts are driven into the heated self-piercing rivets to form riveted joints, and the riveted joints are heated and welded by a high-frequency electromagnetic induction coil, so that the feet, a plurality of The resin pieces are melt-bonded to each other, and the softened resin pieces are riveted to avoid cracks caused by the riveting of the resin pieces. However, high-frequency heating will cause the melting of the material. If it is suitable for dissimilar metal sheets, it may cause a large amount of intermetallic compounds due to the melting reaction of the materials when the dissimilar materials meet, and the structure of the intermetallic compounds is needle-like. Its strength is relatively poor and it is not easy to resist external forces, so that the joined metal sheets are prone to material fatigue during use and cannot effectively resist fatigue.

The invention provides a method for joining and cooling sheet parts, which can apply the original self-piercing riveting equipment to join steel sheet parts with higher strength, and recover the strength of the material by quenching after joining.

The method for joining and cooling sheet parts provided by the present invention includes: providing a first metal sheet and a second metal sheet, wherein the melting point of the first metal sheet is higher than the minimum heating softening temperature of the second metal sheet; stacking in sequence The second metal sheet and the first metal sheet are mounted on a die to form a laminated sheet; After heating the laminated sheet to a first temperature, the first temperature is the softening temperature of the sheet metal of the first metal sheet; direct a self-piercing rivet from the first metal sheet of the laminated sheet towards the The second metal sheet is driven so that the nail feet of the self-piercing rivet pierce the first metal sheet of the upper layer and stay inside the second metal sheet of the lower layer, and correspond to the bottom surface of the second metal sheet at the position of the self-piercing rivet plastically deforming outwards to form a riveted joint to join the first metal sheet and the second metal sheet; cooling the laminated sheet to a second temperature, the second temperature being relative to the first metal sheet Quenching temperature of the material; open the mold and take out the laminated sheet.

In the above embodiment, the material of the first metal sheet and the second metal sheet is steel, and the first temperature is above 400°C.

In one embodiment, the step of heating the laminated sheet further includes a workpiece heating device, and the workpiece heating device uses a moving mechanism to move at an initial position to stop heating and a heating position for heating, the heating position corresponding to The area of the first metal sheet intended to be punched into the self-piercing rivet.

In one embodiment, the above-mentioned workpiece heating device is heated by an electromagnetic induction coil.

In an embodiment, the step of cooling the laminated sheet further includes a workpiece cooling device, the workpiece cooling device is provided with a water channel in the die, and the liquid circulates in the cooling channel to cool the die. of the superimposed sheet.

Another embodiment of the present invention provides a method for joining and cooling sheet parts comprising: providing a first metal sheet and a second metal sheet, wherein the melting point of the first metal sheet is lower than the minimum heating softening temperature of the second metal sheet; Placing the second metal sheet on a die, heating the second metal sheet to a softening temperature and then stopping the heating, the softening temperature being the softening temperature of the second metal sheet; stacking the first metal sheet A superimposed sheet is formed on the second metal sheet; a self-piercing rivet is directed from the first metal sheet toward Drive the superimposed sheet into the second metal sheet, so that the nail feet of the self-piercing rivet pierce the first metal sheet of the upper layer and stay inside the second metal sheet of the lower layer, and correspond to the second metal sheet of the rivet position The bottom surface of the metal sheet is turned outward and plastically deformed to form a riveted joint to join the first metal sheet and the second metal sheet; cool the laminated sheet to a quenching temperature, the quenching temperature is relative to the second metal sheet Quenching temperature of sheet metal material; open the mold to take out the laminated sheet.

In the above embodiment, the material of the first metal sheet is aluminum alloy, the material of the second metal sheet is steel, and the softening temperature is above 400°C.

In the above-mentioned embodiment, the step of heating the laminated sheet further includes a workpiece heating device, and the workpiece heating device uses a moving mechanism to move to an initial position to stop heating and a heating position to perform heating, and the heating position corresponds to The area of the first metal sheet intended to be punched into the self-piercing rivet.

In the above embodiment, the workpiece heating device includes electromagnetic induction coil heating.

In one embodiment, the step of cooling the laminated sheet further includes a workpiece cooling device, the workpiece cooling device is provided with a cooling water channel in the die, and a liquid flows in the cooling water channel to cool the cooling water in the die. The laminated sheet.

Based on the above description, the present invention includes the treatment of workpiece softening before self-piercing joining, so the original equipment can be used to join steel sheet parts with higher strength than the original equipment can be applied. The present invention can apply the original equipment, add a heating device and a quenching device for cooling the die (ie, the lower die), and has high practicability. The present invention can be used to join steel sheet parts with higher strength than the original equipment. Due to the quenching application of the invention in the self-piercing range, both the workpiece and the rivet have the effect of increasing the strength, and can further strengthen the self-piercing riveted joint. In the joining method of the present invention, since the surface of the workpiece is free of oil and water, it is not easy to contaminate the workpiece.

1: Self-piercing riveting equipment

11: Die

111: water flow channel

12: Punch

2: Workpiece heating device

3: Workpiece cooling device

4,4': Self-piercing rivets

41,41': Spike feet

5,5': Riveted joint

L: liquid

L1, L1': initial position

L2, L2': heating position

W1,W1': the first sheet metal

W2,W2': Second sheet metal

Steps S11 to S16: Steps of the method for joining and cooling sheet parts according to an embodiment of the present invention

Steps S21 to S27: the steps of the method for joining and cooling the sheet parts according to another embodiment of the present invention

[Fig. 1] is a flow chart of an embodiment of the method for joining and cooling sheet parts of the present invention; [Fig. 2] to [Fig. 6] are structural flow charts of the method for joining and cooling sheet parts of the present invention in Fig. 1; [Fig. 7] is a flow chart of another embodiment of the method for joining and cooling sheet parts of the present invention; [Fig. 8] to [Fig. 13] are structural flow charts of the method for joining and cooling sheet parts of the present invention in Fig. 7.

The embodiments of the present creation are described in detail as follows in conjunction with the drawings. The accompanying drawings are mainly simplified schematic diagrams, and only illustrate the basic structure of the present creation in a schematic way. Therefore, only the elements related to the present creation are indicated in these drawings. , and the displayed components are not drawn according to the number, shape, size ratio, etc. of the actual implementation. The size of the actual implementation is actually a selective design, and the layout of the components may be more complicated.

The following descriptions of the various embodiments refer to the accompanying drawings to illustrate specific embodiments in accordance with which the invention may be practiced. The directional terms mentioned in the present invention, such as "up", "down", "front", "rear", "left", "right", "inside", "outside", "side", etc., are only for reference Additional schema orientation. Therefore, the directional terms used are used to describe and understand the application, not to limit the application. In addition, in the specification, unless explicitly described to the contrary, the word "comprising" or "comprising" should be construed as This element is meant to be included, but not to the exclusion of any other element.

First, please refer to FIG. 1 and FIG. 2 to FIG. 6 . The method for joining and cooling the sheet parts of this embodiment includes the following steps: Step S11, providing a first metal sheet W1 and a second metal sheet W2, the melting point of the first metal sheet W1 is higher than the minimum heating softening temperature of the second metal sheet W2, for example: the first metal sheet W1 and the second metal sheet W2 are the same High-strength steel; step S12, stack the second metal sheet W2 and the first metal sheet W1 on a die 11 (eg, a die 11 of a self-piercing riveting device 1 ) in sequence, and fix them appropriately, for example Clamp the first metal sheet W1 and the second metal sheet W2 with a clamp to form a laminated sheet; step S13, heat the laminated sheet to a first temperature and then stop heating, and the first temperature is the first temperature The sheet metal softening temperature of the metal sheet W1 is shown in FIG. 2 and FIG. 3; in step S14, a self-piercing rivet 4 is driven from the first metal sheet W1 of the laminated sheet toward the second metal sheet W2 (for example, using a self-piercing rivet 4). A punch 12 of the punch riveting device 1 applies the punching force of the self-piercing rivet 4, so that the nail feet 41 of the self-piercing rivet 4 pierce the first metal sheet W1 of the upper layer and stay inside the second metal sheet W2 of the lower layer, and The bottom surface of the second metal sheet W2 corresponding to the position of the self-piercing rivet 4 is plastically deformed to the outside due to the action of the punch 12 and the die 11 to form a riveted joint 5 to join the first metal sheet W1 and The second metal sheet W2, as shown in Figures 4 and 5; Step S15, cooling the laminated sheet to a second temperature, the second temperature is the quenching temperature relative to the material of the first metal sheet W1, as shown in Figure 5 ; Step S16 , open the mold and take out the laminated sheet that has been joined, as shown in FIG. 6 .

In an example of the present invention, the material of the first metal sheet W1 and the second metal sheet W2 is high-strength steel, and the first temperature (ie, the softening temperature of the high-strength steel) is above 400°C.

As shown in Figure 3 and Figure 4 . The step of heating the laminated sheet (ie step S13) of the present invention also includes a workpiece heating device 2, and the workpiece heating device 2 uses a moving mechanism (because the moving mechanism can use a simple sliding block sliding rail mechanism, connecting Rod mechanism, etc., which are all commonly used mechanical structures, and will not be repeated here. (not shown) move to an initial position L1 to stop heating and a heating position L2 to perform heating, the heating position L2 corresponds to the area of the first metal sheet W1 to be punched into the self-piercing rivet. The above-mentioned workpiece heating device 2 is applicable to the electromagnetic induction coil heating method.

As shown in Figure 4 and Figure 5 . The step of cooling the laminated sheet in the present invention (ie, step S15 ) also includes a workpiece cooling device 3 . The workpiece cooling device 3 is provided with a water flow channel 111 in the die 11 , and the liquid is circulated in the water flow channel 111 flow to cool the laminated sheet in the die 11 in a state where the punch 12 is pressed against the laminated sheet and clamped with the die 11 .

In the above embodiment, the material of the first metal sheet W1 and the second metal sheet W2 are the same or the softening temperatures of the two sheets are similar, that is, when the sheet metal is heated to the first temperature, it will not affect the other sheet metal. mechanical properties of the piece. However, when the softening temperatures of the workpieces are quite different, for example, when the first metal sheet W1' to be processed is an aluminum alloy and the second metal sheet W2' is a steel sheet, it is not suitable or necessary to perform riveting before riveting. Heating together, because the original material of aluminum alloy is softer than that of self-piercing rivets, so it is not necessary to heat and soften it. The method of joining and cooling the sheet in this case is as follows: Please refer to Figure 7 for further details, and compare Figures 8 to 13 . The method for joining and cooling sheet parts in this embodiment includes: step S21, providing a first metal sheet W1' and a second metal sheet W2', the melting point of the first metal sheet W1' is lower than the lowest melting point of the second metal sheet W2' Heating and softening temperature, for example: the first metal sheet W1 is made of aluminum alloy, and the second metal sheet W2 is made of high-strength steel; step S22 , placing the second metal sheet W2 ′ on a die 11 of the self-piercing riveting device 1 ; Step S23, heating the second metal sheet W2' to a softening temperature and then stop heating, and the softening temperature is the sheet material softening temperature of the second metal sheet W2', as shown in Figure 9; Step S24, stacking the first metal sheet W1' on top of the second metal sheet W2' to form a laminated sheet, of course, before riveting, the laminated sheet will be properly fixed together, for example, by pressing plates or clamps Hold it to prevent mutual sliding, as shown in FIG. 11 ; step S25 , drive the self-piercing rivet 4 ′ from the first metal sheet W1 ′ of the superimposed sheet piece toward the second metal sheet W2 ′, so that the self-piercing rivet 4 'The nail feet 41' pierce the first metal sheet W1' of the upper layer and stay inside the second metal sheet W2' of the lower layer, and the bottom surface of the second metal sheet W2' corresponding to the position of the self-piercing rivet 4' faces the outside Plastic deformation is formed to form a riveted joint 5' to join the first metal sheet W1' and the second metal sheet W2', as shown in Figures 11 and 12; Step S26, cooling the laminated sheet to a quenching temperature, where the quenching temperature is Relative to the quenching temperature of the second metal sheet material W2 ′, as shown in FIG. 12 ; in step S27 , the mold is opened to take out the joined laminated sheet, as shown in FIG. 13 .

The material of the first metal sheet W1' is aluminum alloy, the material of the second metal sheet W2' is steel, and the softening temperature of the second metal sheet W2' is 400°C or higher.

In one embodiment, as shown in FIG. 9 and FIG. 10 . In the above-mentioned step of heating the laminated sheet (ie step S23), there is also a workpiece heating device 2, and the workpiece heating device 2 is moved to an initial position L1' by a moving mechanism (not shown) to stop heating and a heating position L2' is heated, and the heating position L2' corresponds to the area of the first metal sheet W1' to be punched into the self-piercing rivet 4'. The workpiece heating device 2 includes an electromagnetic induction coil heating method. Likewise, in an embodiment, please refer to FIG. 11 and FIG. 12 . The above-mentioned step of cooling the laminated sheet (ie, step S26) also includes a workpiece cooling device 3. The workpiece cooling device 3 is provided with a water flow channel 111 in the die 11, and the liquid L circulates in the water flow channel 111 to circulate. The stacked sheet metal in the die 11 is cooled in a state where the punch 12 presses the stacked sheet and is clamped with the die 11 .

The above-mentioned embodiments are only illustrative of the principles, features and effects of the present invention, and are not intended to limit the applicable scope of the present invention. Modifications and changes are made to the above-described embodiments. Any equivalent changes and modifications made by using the contents disclosed in the present invention should still be covered by the following claims. Therefore, the scope of protection of the right of the present invention should be listed in the scope of the patent application.

Steps S21-S27: the steps of the method for joining and cooling the sheet parts according to an embodiment of the present invention

Claims (4)

A method for joining and cooling sheet parts, comprising: providing a first metal sheet and a second metal sheet, wherein the melting point of the first metal sheet is lower than the minimum heating softening temperature of the second metal sheet; placing the second metal sheet sheeting on a die; heating the second metal sheet to a softening temperature and then stopping heating, the softening temperature being the sheet softening temperature of the second metal sheet; stacking the first metal sheet on the second metal sheet A laminated sheet is formed on top of it; a self-piercing rivet is driven from the first metal sheet of the laminated sheet toward the second metal sheet, so that the legs of the self-piercing rivet pierce the first metal sheet of the upper layer. A metal sheet stays inside the second metal sheet of the lower layer, and the bottom surface of the second metal sheet corresponding to the position of the self-piercing rivet is plastically deformed outward to form a riveted joint to join the first metal sheet and the first metal sheet. two metal sheets; cooling the laminated sheet to a quenching temperature, the quenching temperature being the quenching temperature relative to the material of the second metal sheet; and opening the mold to take out the laminated sheet; wherein the step of cooling the laminated sheet There is also a workpiece cooling device, the workpiece cooling device is provided with a water channel in the die, and the liquid circulates in the water channel to cool the laminated sheet in the die. The method for joining and cooling sheet parts according to claim 1, wherein the material of the first metal sheet is aluminum alloy, the material of the second metal sheet is steel, and the softening temperature is above 400°C. According to the method for joining and cooling sheet parts as described in item 1 of the scope of the application, wherein the step of heating the laminated sheet parts further includes a workpiece heating device, and the workpiece heating device is moved to an initial position by a moving mechanism to stop heating and heating. Heating is performed at a heating position, the heating position corresponding to the area of the first metal sheet to be punched into the self-piercing rivet. The method for joining and cooling a sheet piece according to claim 3, wherein the workpiece heating device comprises electromagnetic induction coil heating.

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