A thread rolling die for making narrow break groove ring groove rivets

Abstract

The invention discloses a thread rolling die for making narrow break groove ring groove rivets. It comprises an integrated structure, a locking groove, a break groove and a tail break groove thread rolling plate arranged transversely, each thread rolling plate is sequentially composed of an introduction section, a shaping section and a material stripping section from the front end to the rear end; a break groove thread rolling tooth is arranged in the longitudinal middle of the thread rolling surface of the introduction section of the break groove thread rolling plate, the height-to-width ratio of the thread rolling tooth is 0.5 to 0.75, the thread rolling surfaces on both sides of the thread rolling tooth are inclined, and the shaping section is composed of a front bottom diameter shaping section and a rear outer diameter shaping section; the thread rolling tooth of the invention is conducive to cutting into the workpiece and has sufficient strength, and is suitable for thread rolling of various alloys; a material holding structure with an inclined surface and a material holding structure with an inclined surface is used to temporarily hold the extruded excess material, so that the break groove is formed more stably, and the majority of the material remaining on the inclined surface is gradually compressed back to the break groove by the subsequent pressure plate structure, forming a break groove with an extremely narrow width. The thread rolling die of the invention has good processing performance and stability, the tool strength meets the requirements, and the processing efficiency is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fastener rivet processing, relates to rivet processing die technology, and specifically relates to a thread rolling die used for manufacturing narrow break groove annular groove rivets. Background Art

[0002] At present, ring groove rivets are widely used in various industries. Some special connecting ring groove rivets used in high-speed rail and aviation have narrower breaking grooves than ordinary ring groove rivets. Generally, the breaking groove width is required to be about 0.5mm or even narrower. The same design structure as the ordinary rivet thread rolling die will result in low strength of the breaking groove die and easy damage. Therefore, the processing and production of existing narrow breaking groove ring groove rivets usually adopts machining to process the breaking groove.

[0003] The existing conventional break groove thread rolling plate is directly designed according to the break groove shape. Due to the thin teeth and sheet-like structure, when pressing into the product, the unit area is subjected to great pressure, and it is very easy to be damaged under the conditions of thread rolling production and debugging. There are also break grooves that adopt cutting technology, and the cutting technology requires the purchase of additional equipment. Even if the equipment has automatic loading and clamping functions, the production efficiency is improved compared to manual operation, but compared with thread rolling, its production efficiency is still much different. The speed of processing break grooves by a single device does not exceed 10 pieces per minute.

[0004] For the thread rolling dies of narrow break groove ring groove rivets, especially those with extremely narrow break grooves, in order to meet the life requirements and enable batch thread rolling production while ensuring the width and bottom diameter of the ring groove, save manufacturing costs and improve production efficiency, it is necessary to conduct new exploration, research and design of the thread rolling die structure. Summary of the invention

[0005] The present invention discloses a thread rolling die for producing narrow break groove annular groove rivets according to the shortcomings of the prior art. The present invention aims to provide a thread rolling die with high strength and good stability suitable for processing narrow break groove annular groove rivets.

[0006] The present invention is achieved through the following technical solutions:

[0007] The thread rolling die used for making narrow break groove ring groove rivets includes an integrated structure, a locking groove thread rolling plate, a break groove thread rolling plate and a tail groove thread rolling plate arranged horizontally, and each thread rolling plate of the thread rolling die is a guide section, a shaping section and a stripping section from the front end to the rear end; the characteristics are:

[0008] A break groove thread rolling tooth is arranged in the longitudinal middle of the thread rolling surface of the introduction section of the break groove thread rolling plate, and the cross section of the break groove thread rolling tooth is a deformed triangle structure, and the angle between the two sides of the deformed triangle and the vertical wall of the break groove thread rolling plate is not greater than 45°; the thread rolling surfaces of the break groove thread rolling plate on both sides of the break groove thread rolling tooth are inclined surfaces, and the angle between the inclined surfaces of the thread rolling on both sides of the break groove thread rolling tooth and the thread rolling surface of the break groove thread rolling plate is not greater than 60°; the introduction section is inclined from the front end to the rear end, and the inclination angle of the introduction section is not greater than 2°, constituting that the front end to the rear end of the break groove thread rolling tooth of the introduction section is gradually raised relative to the thread rolling surface;

[0009] The shaping section of the break groove thread rolling plate is composed of a front bottom diameter shaping section and a rear outer diameter shaping section; the bottom diameter shaping section has the same structure as the rear end connection portion of the break groove thread rolling plate introduction section; the outer diameter shaping section includes a transition section and a plane section, the front end of the transition section is transitionally arranged with the end structure of the bottom diameter shaping section, and the break groove thread rolling teeth are removed, and the inclined surfaces on both sides are gradually contracted to the rear end to the middle of the outer diameter shaping section to be removed, forming a plane section of the thread rolling surface structure at the rear of the outer diameter shaping section;

[0010] The front end of the thread rolling surface of the stripping section of the break groove thread rolling plate is transitionally arranged with the rear plane of the outer diameter shaping section, and the plane of the stripping section is inclined and opened toward the rear end.

[0011] Furthermore, the length of the lead-in section of the break groove thread rolling plate is two to five times the circumference of the cylindrical rod of the thread rolling workpiece.

[0012] Furthermore, the length of the lead-in section of the break groove thread rolling plate is twice the circumference of the cylindrical rod of the thread rolling workpiece.

[0013] Furthermore, the length of the bottom diameter shaping section of the break groove thread rolling plate is twice the circumference of the cylindrical rod of the thread rolling workpiece, the length of the outer diameter shaping section of the break groove thread rolling plate is twice the circumference of the cylindrical rod of the thread rolling workpiece, and the length of the transition section and the plane section of the outer diameter shaping section are both twice the circumference of the cylindrical rod of the thread rolling workpiece.

[0014] Furthermore, the length of the stripping section of the thread rolling plate of the breaking groove is one time the diameter of the cylindrical rod of the thread rolling workpiece.

[0015] Furthermore, the angles between the two sides of the deformed triangle in the cross section of the break groove thread rolling teeth and the vertical wall of the break groove thread rolling plate are 20° to 35°.

[0016] Furthermore, the sum of the angles between the two sides of the deformed triangle of the break groove thread rolling tooth cross section and the vertical wall of the break groove thread rolling plate and the angle between the thread rolling inclined surface of the side and the thread rolling surface of the break groove thread rolling plate is not greater than 90°.

[0017] The inclined opening of the stripping section of the breaking groove thread rolling plate is an inclined opening formed by an inclined surface or a chamfered structure; the angle between the inclined surface and the thread rolling surface is not greater than 10°, and the fillet radius of the chamfered structure is not less than the tooth height of the thread rolling teeth in the bottom diameter shaping section.

[0018] The two sides of the deformed triangle of the cross-section of the break groove thread rolling teeth are deformed triangle structures composed of straight lines, multiple arcs, or arcs plus straight lines. The angle between the tangent or straight line of the arc at the bottom end of each side of the deformed triangle and the vertical wall of the break groove thread rolling plate is not greater than 45°.

[0019] The ratio of the break groove thread rolling tooth height to the tooth bottom width is between 0.5 and 0.75.

[0020] In conventional thread rolling plates, due to the narrow width of the breaking groove of the narrow breaking ring groove rivet, the thread rolling plates processed according to the shape of the narrow breaking groove are insufficient in strength and are easily damaged during the thread rolling process, and the life of the thread rolling plates cannot meet production needs. The thread rolling tooth structure is redesigned, the thread rolling teeth are widened to improve strength, a transition accommodation space for extruded materials is designed, and a back-pressure thread rolling structure is designed. During the thread rolling process of the breaking groove thread rolling plate of the present invention, excess extruded material is accommodated by the thread rolling inclined surface inclined outward, and the majority of the material remaining on the inclined surface is gradually compressed back into the breaking groove by the pressure plate structure behind the thread rolling plate, forming a breaking groove with an extremely narrow width.

[0021] During the entire thread rolling process, the thread rolling die of the present invention first cuts into the ring groove rivet workpiece by the locking groove thread rolling plate or the tail groove thread rolling plate, driving the workpiece to be stably pressed into the break groove thread rolling plate. As the extrusion goes deeper, the locking groove thread rolling plate and the tail groove thread rolling plate jointly complete the forming of the workpiece on the break groove thread rolling plate.

[0022] The benefits of the present invention: The ratio of the thread rolling tooth height to the tooth width of the present invention is between 0.5 and 0.75, which is not only conducive to the thread rolling teeth cutting into the workpiece, but also has sufficient strength and is suitable for the thread rolling of various alloys; a slanted material holding structure with an appropriate angle to the thread rolling surface is used to temporarily hold the extruded excess material, making the forming of the break groove more stable, and the subsequent pressure plate structure gradually compresses the majority of the remaining material on the slant back into the break groove to form a break groove with an extremely narrow width. The thread rolling die of the present invention has good processing performance and stability, and the tool strength meets the requirements. The thread rolling can complete the processing of three-stage tooth profiles in one time, and the processing efficiency is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the narrow break groove ring groove rivet made by the present invention;

[0024] Figure 2 It is a partial schematic diagram of the breaking groove of the narrow breaking groove ring groove rivet;

[0025] Figure 3 It is a schematic diagram of the side profile of the thread rolling die of the present invention;

[0026] Figure 4 It is a schematic diagram of the end face profile of the thread rolling die of the present invention;

[0027] Figure 5It is a schematic diagram of the three-dimensional structure of the thread rolling plate of the thread rolling die breaking groove of the present invention;

[0028] Figure 6 It is a schematic diagram of the surface structure of the thread rolling plate of the thread rolling die breaking groove of the present invention;

[0029] Figure 7 It is a schematic diagram of the side structure of the thread rolling plate of the thread rolling die breaking groove of the present invention;

[0030] Figure 8 It is a schematic diagram of the structure of the break groove thread rolling tooth of the present invention;

[0031] Fig. 9 yes Figure 6 Schematic diagram of the structure of the middle B11 section;

[0032] Fig.10 yes Figure 6 Schematic diagram of the structure of the middle B12 section and B21 section;

[0033] Fig.11 yes Figure 6 Schematic diagram of the structure of the middle B31 section;

[0034] Fig.12 yes Figure 6 Schematic diagram of the structure of the middle B32 section;

[0035] In the figure, 1 is the introduction section, 2 is the shaping section, 3 is the stripping section, 4 is the thread rolling slope, 5 is the thread rolling teeth, and 6 is the thread rolling surface;

[0036] A is the locking groove thread rolling plate, B is the break groove thread rolling plate, C is the tail groove thread rolling plate, E is the inclination angle of the introduction section, F is the inclination angle of the stripping section, B1 is the break groove introduction section, B2a is the bottom diameter shaping section, B2b is the outer diameter shaping section, and B3 is the break groove stripping section; B11, B21, B22, B31, and B32 represent the sections of the break groove thread rolling plate, a is the locking groove, b is the break groove, c is the tail groove, D1 is the front end diameter of the break groove, D2 is the rear end diameter of the break groove, H is the width of the break groove, W1 is the front end rod length of the break groove, W2 is the rear end rod length of the break groove, α1 is the right angle of the break groove thread rolling teeth, α2 is the left angle of the break groove thread rolling teeth, β1 is the right angle of the break groove thread rolling inclined surface, β2 is the left angle of the break groove thread rolling inclined surface, g is the break groove thread rolling tooth height, and h is the break groove thread rolling tooth bottom width. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with specific implementation methods. The specific implementation methods are further descriptions of the principles of the present invention and do not limit the present invention in any way. Technologies that are the same or similar to the present invention do not exceed the scope of protection of the present invention.

[0038] Combined with the attached pictures.

[0039] The invention discloses a thread rolling die for manufacturing narrow break groove ring groove rivets, comprising an integrated structure, a locking groove thread rolling plate A, a break groove thread rolling plate B and a tail groove thread rolling plate C arranged transversely. Figure 4 As shown, Figure 4 It is a schematic diagram of the end face profile of the thread rolling die of the present invention. According to the break groove ring groove rivet thread rolling structure, it is an integrated structure of the locking groove thread rolling plate A, the break groove thread rolling plate B and the tail groove thread rolling plate C. Figure 3 As shown, Figure 3 It is a schematic diagram of the side profile of the thread rolling die of the present invention. The thread rolling die comprises an introduction section 1, a shaping section 2, and a stripping section 3 from the front end to the rear end.

[0040] The longitudinal center line of the thread rolling surface 6 of the introduction section of the thread rolling plate of the break groove is provided with a break groove thread rolling tooth 5, and the cross section of the break groove thread rolling tooth 5 is a triangular structure, and the angle between the two sides of the triangle and the vertical wall of the thread rolling plate of the break groove is not greater than 45°. The two sides of the cross section triangle of the thread rolling tooth of the break groove of the present invention can also be a deformed triangular structure composed of multiple arcs, or arcs plus straight lines, and the angle between the tangent or straight line of the arc at the bottom end of each side of the deformed triangle and the vertical wall of the thread rolling plate of the break groove is not greater than 45°. The ratio of the height g of the thread rolling tooth of the break groove to the width h of the bottom of the tooth is between 0.5 and 0.75.

[0041] like Figure 8 As shown, the angles between the two sides of the triangle of the break groove thread rolling tooth 5 and the vertical wall of the break groove thread rolling plate include the right angle α1 of the break groove thread rolling tooth and the left angle α2 of the break groove thread rolling tooth. The thread rolling surfaces of the break groove thread rolling plate on both sides of the break groove thread rolling tooth 5 are both inclined surfaces, such as Figure 8 As shown, the angle between the thread rolling bevel 4 and the thread rolling surface 6 of the break groove thread rolling plate is not greater than 60°, and in the figure, it includes the right angle β1 of the thread rolling bevel of the break groove and the left angle β2 of the thread rolling bevel of the break groove; the break groove introduction section B1 is inclined from the front end to the rear end, and the angle E of the introduction section is not greater than 2°, forming the break groove introduction section B1. The break groove thread rolling teeth 5 and the thread rolling bevel 4 are gradually raised from the front end to the rear end relative to the thread rolling surface 6; forming a longitudinal Fig. 9 Schematic diagram of the structure.

[0042] The shaping section 2 of the break groove thread rolling plate B is composed of a front bottom diameter shaping section B2a and a rear outer diameter shaping section B2b; the bottom diameter shaping section B2a has the same structure as the rear end connecting portion of the break groove introduction section B1, that is, Fig.10 As shown, the structures of the B12 section and the B21 section are the same; the outer diameter shaping section B2b includes a transition section and a plane section, the front end of the transition section is transitionally arranged with the end structure of the bottom diameter shaping section B2a, and the thread rolling teeth 5 of the break groove are cancelled, and the inclined surfaces 4 on both sides gradually shrink to the rear end and are cancelled in the middle of the outer diameter shaping section B2b, as shown in FIG. Fig.11 As shown, Fig.11There is no breaking groove thread rolling tooth 5 in the middle, and the inclined surfaces 4 on both sides are combined with the thread rolling surface 6 to form a plane section of the thread rolling surface 6 structure at the rear of the outer diameter shaping section B2b, such as Fig.12 shown.

[0043] The front end of the thread rolling surface 6 of the stripping section B3 of the thread rolling plate of the breaking groove is transitionally arranged with the rear plane of the outer diameter shaping section B2b, and the plane is inclined and opened toward the rear end.

[0044] Usually, the thread rolling plates on the thread rolling equipment are divided into dynamic thread rolling plates and fixed thread rolling plates, and the design of each tooth on the dynamic thread rolling plates and the fixed thread rolling plates is the same as the product.

[0045] As shown in the figure, the moving thread rolling plate and the fixed thread rolling plate of the ring groove rivet thread rolling die are composed of three sections, namely the introduction section 1, the shaping section 2, and the stripping section 3. The shaping section 2 of the break groove thread rolling plate B of the narrow break ring groove rivet has two sections, namely the break groove bottom diameter shaping section B2a and the break groove outer diameter shaping section B2b. The break groove bottom diameter shaping section B2a and the break groove outer diameter shaping section B2b have different functions. The bottom diameter shaping section B2a stabilizes the bottom diameter size of the break groove, and the same heat treatment process is used to make the break performance close to the same. The outer diameter shaping section B2b first presses most of the extruded material back into the break groove to form an extremely narrow break groove without changing the bottom diameter of the break groove, and secondly makes the cones on both sides of the break groove smoother.

[0046] The present invention calculates the required length of the break groove thread rolling plate B according to the maximum deformation position. The break groove thread rolling plate length = break groove stripping section length + break groove introduction section length + break groove bottom diameter shaping section length + break groove outer diameter shaping section length.

[0047] The length of the stripping section 3 is equal to one times the diameter of the workpiece at the cylindrical rod forming part of the workpiece. The stripping section adopts a bevel opening design or a chamfer design. The inclination angle F of the stripping section with a bevel opening design or the inclination angle F of the chamfer tangent is not greater than 10°, preferably not greater than 5°. The chamfer design has a smoother and larger-amplification stripping space, and the demoulding is performed by chamfering. When demoulding with a fillet, the radius of the fillet should not be less than the tooth height of the bottom diameter shaping section.

[0048] The lead-in section 1 is tilted at an angle, and the maximum angle of the lead-in section tilt angle E should not be greater than 2°. The length of the lead-in section 1 is 2 to 5 times the circumference of the cylindrical rod of the workpiece before thread rolling, that is, 2πD to 5πD, where D is the diameter of the cylindrical rod of the workpiece. The length of the lead-in section 1 of the locking groove thread rolling plate A or the tail groove thread rolling plate C is not greater than 2 times the circumference of the cylindrical rod of the product workpiece at that location, that is, 2πD. The greater the deformation or the metal that is difficult to deform, the longer the lead-in length is required.

[0049] The length of the bottom diameter shaping section shall not be less than twice the circumference of the cylindrical rod of the workpiece before thread rolling, that is, 2πD; the length of the outer diameter shaping section shall not be less than twice the circumference of the cylindrical rod of the workpiece before thread rolling, that is, 2πD.

[0050] According to the above-mentioned design requirements for the length of the ring groove rivet thread rolling die, determine the thread rolling equipment suitable for installing the thread rolling die of this length. Generally, the longer the length of the lead-in section 1, the better the service life of the thread rolling plate; the longer the length of the shaping section 2, the better the appearance quality of the workpiece after thread rolling and the more stable the size, but it is advisable not to exceed four times the circumference of the workpiece.

[0051] The present invention arranges the break groove thread rolling teeth 5 on the longitudinal center line of the thread rolling surface of the break groove introduction section B1. The break groove thread rolling teeth 5 can be a triangular structure, and can also have other deformed triangular structures. The triangular break groove thread rolling teeth 5 are arranged in the front of the break groove introduction section B1, and the single-side angle of the deformed triangle is not greater than 45°, and the preferred range is 20° to 35°. The tip angle of the break groove thread rolling teeth 5 needs to be rounded, and the rounded angle should be as small as possible, preferably not exceeding R0.2. The break groove thread rolling teeth 5 can also be a deformed triangular structure, such as a semi-circular arc structure, that is, the tooth profile cross-section is a circular arc structure. The triangle is suitable for a shape structure with a deeper pressing depth and a relatively small deformation amount; the arc is suitable for a shape structure with a shallower pressing depth and a larger pressing amount.

[0052] In order to accommodate the extruded material during the thread rolling process of the rivet, the thread rolling inclined surfaces 4 of the breaking groove are arranged on both sides of the bottom of the thread rolling teeth 5 of the breaking groove at the rear of the breaking groove introduction section 1. Other shapes of structures can also be arranged to accommodate the extruded material when the thread rolling plate cuts into the rivet. The space of the structure that can accommodate the extruded material should not be less than the volume of the extruded material.

[0053] The thread rolling surface of the breaking groove bottom diameter shaping section B2a has no angle with the horizontal, and smoothly transitions with the breaking groove introduction section 1 to be provided with a breaking groove thread rolling inclined surface 4 for accommodating the extruded material.

[0054] The length of the break groove outer diameter shaping section B2b is designed to be composed of two parts, the first part is the transition section, and the second part is the plane section. The front end of the transition section is the break groove bottom diameter shaping section B2a, which is consistent with the break groove thread rolling inclined surface 4 for accommodating the extruded material, and gradually transitions to a complete break groove thread rolling surface 6. The transition section should be at least twice the circumference of the workpiece cylindrical rod, that is, 1πD; the plane section should also be at least twice the circumference of the workpiece cylindrical rod, that is, 1πD.

[0055] The inclination angle E of the lead-in section is as small as possible, and should not be greater than 2°, preferably not greater than 1°, when all parameters are met. At the same time, the lead-in section length of the locking groove thread rolling plate A or the tail groove thread rolling plate C is shorter than the length of the break groove lead-in section B, that is, the locking groove thread rolling plate A and the tail groove thread rolling plate C must cut into the workpiece earlier than the break groove thread rolling plate B; the locking groove thread rolling plate A and the tail groove thread rolling plate C that cut into the workpiece first allow the workpiece to be stabilized in the direction perpendicular to the movement direction of the thread rolling plate, and ensure that the workpiece can roll without slipping with the movement of the thread rolling plate.

Claims

1. A thread rolling die for making narrow break groove ring groove rivets, comprising an integrated structure, a locking groove thread rolling plate, a break groove thread rolling plate and a tail groove thread rolling plate arranged transversely, each thread rolling plate of the thread rolling die is a guide section, a shaping section and a stripping section from the front end to the rear end; characterized in that: A break groove thread rolling tooth is arranged in the longitudinal middle of the thread rolling surface of the break groove thread rolling plate introduction section, and the cross section of the break groove thread rolling tooth is a deformed triangle structure, and the angle between the two sides of the deformed triangle and the vertical wall of the break groove thread rolling plate is not greater than 45°; the angle between the thread rolling inclined surfaces on both sides of the break groove thread rolling tooth and the thread rolling surface of the break groove thread rolling plate is not greater than 60°; the break groove thread rolling plate introduction section is inclined from the front end to the rear end, and the inclination angle of the introduction section is not greater than 2°, constituting that the break groove thread rolling teeth and the thread rolling inclined surfaces of the introduction section are gradually raised relative to the thread rolling surface from the front end to the rear end; The shaping section of the break groove thread rolling plate is composed of a front bottom diameter shaping section and a rear outer diameter shaping section; the bottom diameter shaping section has the same structure as the rear end connection portion of the break groove thread rolling plate introduction section; the outer diameter shaping section includes a transition section and a plane section, the front end of the transition section is transitionally arranged with the end structure of the bottom diameter shaping section, and the break groove thread rolling teeth are removed, and the thread rolling inclined surfaces on both sides gradually shrink to the middle of the outer diameter shaping section at the rear end, and the thread rolling surface structure at the rear of the outer diameter shaping section is a plane section; The front end of the thread rolling surface of the stripping section of the drawing groove thread rolling plate is transitionally arranged with the rear plane of the outer diameter shaping section, and the plane is inclined and opened toward the rear end.

2. The thread rolling die for producing narrow break groove ring groove rivets according to claim 1, characterized in that: The length of the lead-in section of the break groove thread rolling plate is two to five times the circumference of the cylindrical rod of the thread rolling workpiece.

3. The thread rolling die for producing narrow break groove ring groove rivets according to claim 1, characterized in that: The length of the bottom diameter shaping section of the break groove thread rolling plate is twice the circumference of the cylindrical rod of the thread rolling workpiece, the length of the outer diameter shaping section of the break groove thread rolling plate is twice the circumference of the cylindrical rod of the thread rolling workpiece, and the length of the transition section and the plane section of the outer diameter shaping section are both once the circumference of the cylindrical rod of the thread rolling workpiece.

4. The thread rolling die for producing narrow break groove ring groove rivets according to claim 1, characterized in that: The length of the stripping section of the thread rolling plate of the breaking groove is one time the diameter of the cylindrical rod of the thread rolling workpiece.

5. The thread rolling die for producing narrow break groove ring groove rivets according to claim 1, characterized in that: The angles between the two sides of the deformed triangle of the cross section of the break groove thread rolling teeth and the vertical wall of the break groove thread rolling plate are 20° to 35°.

6. The thread rolling die for producing narrow break groove ring groove rivets according to claim 1, characterized in that: The inclined opening of the stripping section of the breaking groove thread rolling plate is an inclined opening formed by an inclined surface or a chamfered structure; the angle between the inclined surface and the thread rolling surface is not greater than 10°, and the fillet radius of the chamfered structure is not less than the tooth height of the thread rolling teeth in the bottom diameter shaping section.

7. The thread rolling die for producing narrow break groove ring groove rivets according to claim 1, characterized in that: The two sides of the deformed triangle of the cross-section of the break groove thread rolling teeth are deformed triangle structures composed of straight lines, multiple arcs, or arcs plus straight lines. The angle between the tangent or straight line of the arc at the bottom end of each side of the deformed triangle and the vertical wall of the break groove thread rolling plate is not greater than 45°.

8. The thread rolling die for producing narrow break groove ring groove rivets according to claim 1, characterized in that: The ratio of the break groove thread rolling tooth height to the tooth bottom width is 0.5 to 0.75.

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