Rivetless connection forming device and rivetless connection process

Abstract

The present invention discloses a rivetless connection forming device, comprising an upper punch, a forming structure and a lower punch, wherein the forming structure is located between the upper punch and the lower punch; the forming structure comprises a bottom die and a split die installed in the bottom die, the bottom die comprises a circular bottom plate, a circular groove is provided in the middle of the circular bottom plate, a through hole is provided in the middle of the circular groove, an annular retaining ring is provided on the circumference of the outer periphery of the circular groove, an annular side plate is provided on the circumference of the outer periphery of the circular bottom plate, and the split die comprises a plurality of sub-petal dies. The present invention also discloses a rivetless connection process, which adopts the rivetless connection forming device as described above, and the process comprises the following steps: step one: clamping stage; step two: forward stamping stage; step three: reverse hammering stage; step four: demolding stage. The invention effectively ensures the mechanical properties of the joint through the synergistic effect of the two processes of forward stamping and reverse hammering, while also effectively reducing the height of the joint protrusion.

Description

Technical Field

[0001] The present invention relates to the technical field of rivetless connection, and in particular to a rivetless connection forming device and a rivetless connection process based on the device. Background Art

[0002] Rivetless joining technology is a new type of joining process. Due to its significant advantages, such as lightweight, high efficiency, low cost, and environmental friendliness, it has been widely used in the manufacture of lightweight thin-plate connections, such as automobile bodies, household appliance housings, and launch vehicles. Currently, rivetless joining generally suffers from the disadvantage of high joint protrusion, which makes it unsuitable for external surfaces or functional surfaces (such as friction surfaces). Furthermore, the mechanical properties of traditional rivetless joints are relatively low. There are two main existing solutions to this problem. The first is to use completely new rivetless joining processes, such as flat-point rivetless joining and pre-punched rivetless joining, which can solve the problem of joint protrusion. However, the mechanical properties of the joints are lower than those of traditional rivetless joints. The second is to reverse-stamp the traditional rivetless joints, such as the two-step rivetless stamping process. This process can solve the problems of joint protrusion and low mechanical properties, but requires the rivetless joint to be placed in the press in reverse, requiring secondary clamping, which increases the operational difficulty and processing time, making it difficult to implement in engineering applications. Therefore, it is necessary to improve the existing technology. Summary of the Invention

[0003] The purpose of the present invention is to provide a rivetless connection forming device to solve the problems in the prior art that the rivetless connection joint has a high protrusion and cannot be used for external surfaces or functional surfaces, and at the same time, the mechanical properties of the joint are relatively low.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is:

[0005] A rivetless connection forming device, characterized in that it comprises an upper punch, a forming structure and a lower punch, wherein the forming structure is located between the upper punch and the lower punch;

[0006] The molding structure includes a bottom mold and a split mold installed in the bottom mold, the bottom mold includes a circular bottom plate, a circular groove is provided in the middle of the circular bottom plate, a through hole is provided in the middle of the circular groove, an annular retaining ring is provided on the circumference of the outer periphery of the circular groove, an annular side plate is provided on the circumference of the outer periphery of the circular bottom plate, a plurality of limiting holes are provided at equal intervals on the annular side plate, a partition is provided in the middle between each two adjacent limiting holes, the partition is vertically connected to the circular bottom plate, and a flap mold installation cavity is formed between the two adjacent partitions, the circular bottom plate, the annular side plate and the annular retaining ring;

[0007] The split mold includes a plurality of sub-petal molds, each of which has the same structure and includes a ring sector. The plurality of ring sector bodies can be combined to form an annular structure. A lug is provided in the middle of the outer edge of the ring sector. The sub-petal mold is detachably installed in the petal mold installation cavity and the lug passes through the corresponding limiting hole.

[0008] The lower punch includes a connecting cylinder passing through the through hole, a disc is vertically provided on the top of the connecting cylinder, the disc is located in the circular groove, and a truncated cone-shaped protrusion is provided in the middle of the disc;

[0009] An annular lateral flow space is formed between the split mold, the annular retaining ring and the truncated cone-shaped protrusion.

[0010] Preferably, an annular pressure ring is provided between the upper punch and the forming structure.

[0011] Preferably, the number of the sub-petal molds and the limiting holes is the same, both four.

[0012] Preferably, the width of the top surface of the ring sector is greater than the width of the bottom surface, and a slope is formed on the inner edge of the ring sector.

[0013] Preferably, the diameter of the disc is the same as the diameter of the circular groove.

[0014] Preferably, the connecting column, the disc and the frustum-shaped protrusion are an integrated structure.

[0015] Preferably, the limiting hole is strip-shaped and arranged horizontally.

[0016] Preferably, the upper punch and the lower punch are respectively provided with a cylinder for pushing the upper punch to punch downward and the lower punch to hammer upward.

[0017] In addition, another object of the present invention is to provide a rivetless connection process, which uses the rivetless connection forming device as described above, and the process includes the following steps:

[0018] Step 1: Clamping stage,

[0019] Install each sub-petal mold in the corresponding petal mold installation cavity, then place the upper and lower plates on the bottom mold, and press the plates downward with the annular blank holder;

[0020] Step 2: Forward stamping stage,

[0021] The upper punch presses downward, causing the sheet to continuously flow toward the annular lateral flow space and form a mechanical lock;

[0022] Step 3: Reverse hammering stage,

[0023] Keeping the current height position of the annular blank holder unchanged, the upper punch retreats upward to the preset position, and then the lower punch hammers upward the bottom of the mechanical lock multiple times until the lower punch reaches the preset position;

[0024] Step 4: Demolding stage,

[0025] Move the upper punch and the annular blank holder away, move the lower punch down to its initial position, and then move the bottom die down. During the downward movement, the mechanical lock contacts the top of the inner edge of the sub-petal die and drives the sub-petal die to flip upward until the mechanical lock disengages from the bottom die.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention effectively ensures the mechanical properties of the joint through the synergistic effect of the two processes of forward stamping and reverse hammering. During the forward stamping process, an annular lateral flow space is formed by rationally designing the internal structure of the bottom die, so that the mechanical interlocking amount of the plate is increased, and the mechanical properties are significantly improved. During the reverse hammering process, under the multiple hammering and piercing action of the lower punch, the plate will undergo further lateral flow, so that the mechanical interlocking amount of the joint is further increased, the mechanical properties are further enhanced, and the height of the joint protrusion is effectively reduced.

[0028] (2) The present invention designs the split mold structure as a combination of multiple sub-petal mold structures. After the two processes of forward stamping and reverse hammering are completed, as the bottom mold moves downward, the joint contacts the top inner edge of the sub-petal mold and drives the sub-petal mold to flip upward, providing space for the demoulding of the joint and facilitating the demoulding of the mechanical lock.

[0029] (3) The rivetless connection process of the present invention conforms to engineering practice, integrates forward stamping and reverse hammering, and can reshape the joint by reverse hammering after downward stamping, without the need for secondary clamping and secondary stamping, which greatly reduces the difficulty of operation and shortens the process time. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are only some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 It is a cross-sectional view of the overall structure of the present invention.

[0032] Figure 2 It is a schematic diagram of the bottom mold structure of the present invention.

[0033] Figure 3It is a schematic diagram of the petal mold structure of the present invention.

[0034] Figure 4 It is a schematic diagram of the lower punch structure of the present invention.

[0035] Figure 5 It is a schematic diagram of the forward stamping stage of the present invention.

[0036] Figure 6 It is a schematic diagram of the reverse hammer pressing stage of the present invention.

[0037] In the figure: 1. Upper punch; 2. Annular pressure ring; 3. Lower punch; 4. Bottom die; 5. Petal die; 6. Circular bottom plate; 7. Circular groove; 8. Through hole; 9. Annular retaining ring; 10. Annular side plate; 11. Limiting hole; 12. Partition; 13. Petal die mounting cavity; 14. Sub-petal die; 15. Annular sector; 16. Lug; 17. Inclined surface; 18. Connecting column; 19. Disc; 20. Cone-shaped protrusion; 21. Annular lateral flow space; 22. Upper plate; 23. Lower plate; 24. Mechanical lock. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0039] Furthermore, in the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "fixed" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical connections; direct connections or indirect connections via an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0040] Example 1

[0041] like Figure 1 As shown, a preferred embodiment of the present invention provides a rivetless connection forming device, comprising: an upper punch 1, an annular blank holder 2, a forming structure, and a lower punch 3. The annular blank holder 2 is located between the upper punch 1 and the forming structure. The function of the annular blank holder 2 is to prevent the plate from warping during the punching process. The forming structure is located between the upper punch 1 and the lower punch 3.

[0042] The molding structure includes a bottom mold 4 and a split mold 5 installed in the bottom mold 4.

[0043] Among them, such as Figure 2As shown, the bottom mold 4 includes a circular bottom plate 6, a circular groove 7 is provided in the middle of the circular bottom plate 6, and a through hole 8 is provided in the middle of the circular groove 7 that passes through the circular bottom plate 6. Specifically, the diameter of the circular bottom plate 6 is larger than the diameter of the circular groove 7, and the diameter of the circular groove 7 is larger than the diameter of the through hole 8.

[0044] On the circular bottom plate 6, an annular retaining ring 9 is provided on the circumference of the outer periphery of the circular groove 7. The function of the annular retaining ring 9 is to limit the installation of the sub-lobe mold below and prevent the sub-lobe mold from moving toward the inside of the bottom mold 4.

[0045] An annular side plate 10 is provided circumferentially around the outer periphery of the circular base plate 6. Multiple limiting holes 11 are provided on the annular side plate 10 at equal intervals. Specifically, there are four limiting holes 11, each of which is strip-shaped and arranged horizontally. A partition plate 12 is provided midway between each pair of adjacent limiting holes 11 and is vertically connected to the circular base plate 6. A flap mold mounting cavity 13 is formed between two adjacent partition plates 12, the circular base plate 6, the annular side plate 10, and the annular retaining ring 9, forming four flap mold mounting cavities 13.

[0046] Among them, such as Figure 3 As shown, the split mold 5 includes a plurality of sub-lobe molds 14. The number of sub-lobe molds 14 is the same as the number of the above-mentioned limiting holes 11, which is four. Each sub-lobe mold 14 has the same structure. The sub-lobe mold 14 includes a ring sector 15. The combination of four ring sector bodies can form an annular body structure. A lug 16 is provided in the middle of the outer edge of the ring sector body 15. The lug 16 is adapted to the above-mentioned limiting holes 11. The four sub-lobe molds 14 are respectively detachably installed in the corresponding lobe mold installation cavity 13, and the lug 16 passes through the corresponding limiting holes 11.

[0047] Furthermore, the width of the top surface of the ring sector 15 is greater than the width of the bottom surface, thereby forming a slope 17 on the inner edge of the ring sector 15 .

[0048] Among them, such as Figure 4 As shown, the lower punch 3 includes a connecting cylinder 18, the diameter of the connecting cylinder 18 is the same as the diameter of the through hole 8, the connecting cylinder 18 passes through the through hole 8, and a disc 19 is vertically provided at the top of the connecting cylinder 18, the diameter of the disc 19 is the same as the diameter of the circular groove 7, the disc 19 is located in the circular groove 7, and a frustum-shaped protrusion 20 is provided in the middle of the disc 19.

[0049] Furthermore, the connecting column 18 , the disc 19 and the frustum-shaped protrusion 20 are an integrated structure to increase the strength of the lower punch 3 .

[0050] An annular lateral flow space 21 is formed between the split mold 5 , the annular retaining ring 9 and the truncated cone-shaped protrusion 20 .

[0051] Furthermore, the upper punch 1 and the lower punch 3 are respectively equipped with a cylinder for pushing the upper punch 1 to punch downward and the lower punch 3 to hammer upward.

[0052] Example 2

[0053] This embodiment also proposes a rivet-free connection process based on the above-mentioned rivet-free connection forming device, including the following steps:

[0054] Step 1: Clamping stage,

[0055] The four sub-flank molds 14 are respectively installed in the corresponding flap mold installation cavities 13, and then the upper plate 22 and the lower plate 23 are placed on the bottom mold 4, and finally the annular pressure ring 2 is pressed downward to tighten the plates.

[0056] Step 2: Forward stamping stage,

[0057] like Figure 5 As shown, the upper punch 1 punches downward, causing plastic deformation between the upper plate 22 and the lower plate 23. During the downward punching process of the upper punch 1, the plates continuously flow into the annular lateral flow space 21 and form a mechanical lock 24.

[0058] Step 3: Reverse hammering stage,

[0059] like Figure 6 As shown, the current height position of the annular blank holder 2 is kept unchanged, the upper punch 1 is withdrawn upward to a preset position, and then the lower punch 3 repeatedly hammers upward on the bottom of the mechanical lock 24 formed in step 2 until the lower punch 3 reaches the preset position. Under the multiple hammering and pressing action of the lower punch 3, the sheet material will undergo further lateral flow, thereby further increasing the mechanical interlocking amount of the joint, further enhancing the mechanical properties, and effectively reducing the height of the joint protrusion.

[0060] Step 4: Demolding stage,

[0061] The upper punch 1 and the annular pressure ring 2 are removed, the lower punch 3 is moved down to the initial position, and then the bottom mold 4 is moved down. During the downward movement, the mechanical lock 24 contacts the top of the inner edge of the sub-flap mold 14 and drives the sub-flap mold 14 to flip upward. At the same time, the lug 16 is lifted up to provide space for the demolding of the joint until the mechanical lock 24 is disengaged from the bottom mold 4. After disengagement, the sub-flap mold 14 falls back to its initial position in the bottom mold 4 under the action of gravity.

[0062] In summary, the present invention effectively ensures the mechanical properties of the joint through the synergistic effect of the two processes of forward stamping and reverse hammering. During the forward stamping process, an annular lateral flow space is formed by rationally designing the internal structure of the bottom die, so that the mechanical interlocking amount of the mechanical lock formed by the plate is increased, and the mechanical properties are significantly improved. During the reverse hammering process, under the action of multiple hammering and piercing of the lower punch, the plate will undergo further lateral flow, so that the mechanical interlocking amount of the joint is further increased, the mechanical properties are further enhanced, and at the same time, the height of the joint protrusion is effectively reduced.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A rivetless connection forming device, characterized in that: It includes an upper punch, a forming structure and a lower punch, wherein the forming structure is located between the upper punch and the lower punch; The molding structure includes a bottom mold and a split mold installed in the bottom mold, the bottom mold includes a circular bottom plate, a circular groove is provided in the middle of the circular bottom plate, a through hole is provided in the middle of the circular groove, an annular retaining ring is provided on the circumference of the outer periphery of the circular groove, an annular side plate is provided on the circumference of the outer periphery of the circular bottom plate, a plurality of limiting holes are provided at equal intervals on the annular side plate, a partition is provided in the middle between each two adjacent limiting holes, the partition is vertically connected to the circular bottom plate, and a flap mold installation cavity is formed between the two adjacent partitions, the circular bottom plate, the annular side plate and the annular retaining ring; The split mold includes a plurality of sub-petal molds, each of which has the same structure and includes a ring sector. The plurality of ring sector bodies can be combined to form an annular structure. A lug is provided in the middle of the outer edge of the ring sector. The sub-petal mold is detachably installed in the petal mold installation cavity and the lug passes through the corresponding limiting hole. The width of the top surface of the ring sector is greater than the width of the bottom surface, and a slope is formed on the inner edge of the ring sector; The lower punch includes a connecting cylinder passing through the through hole, a disc is vertically provided on the top of the connecting cylinder, the disc is located in the circular groove, and a truncated cone-shaped protrusion is provided in the middle of the disc; An annular lateral flow space is formed between the split mold, the annular retaining ring and the truncated cone-shaped protrusion.

2. A rivetless connection forming device according to claim 1, characterized in that: An annular pressure ring is provided between the upper punch and the forming structure.

3. The rivetless connection forming device according to claim 1, characterized in that: The number of the sub-petal molds and the limiting holes is the same, both being four.

4. The rivetless connection forming device according to claim 1, characterized in that: The diameter of the disc is the same as the diameter of the circular groove.

5. The rivetless connection forming device according to claim 1, characterized in that: The connecting column, the disc and the frustum-shaped protrusion are an integrated structure.

6. The rivetless connection forming device according to claim 1, characterized in that: The limiting hole is strip-shaped and arranged horizontally.

7. The rivetless connection forming device according to claim 1, characterized in that: The upper punch and the lower punch are respectively provided with cylinders for pushing the upper punch to punch downward and the lower punch to hammer upward.

8. A rivetless connection process, characterized in that: Using the rivetless connection forming device according to any one of claims 1 to 7, the process includes the following steps: Step 1: Clamping stage, Install each sub-petal mold in the corresponding petal mold installation cavity, then place the upper and lower plates on the bottom mold, and press the plates downward with the annular blank holder; Step 2: Forward stamping stage, The upper punch presses downward, causing the sheet to continuously flow toward the annular lateral flow space and form a mechanical lock; Step 3: Reverse hammering stage, Keeping the current height position of the annular blank holder unchanged, the upper punch retreats upward to the preset position, and then the lower punch hammers upward the bottom of the mechanical lock multiple times until the lower punch reaches the preset position; Step 4: Demolding stage, Move the upper punch and the annular blank holder away, move the lower punch down to its initial position, and then move the bottom die down. During the downward movement, the mechanical lock contacts the top of the inner edge of the sub-petal die and drives the sub-petal die to flip upward until the mechanical lock disengages from the bottom die.

Images