Forming process and forming device of semi-hexagonal pull rivet nut and semi-hexagonal pull rivet nut

Abstract

The application provides a forming process, a forming device and a semi-hexagonal pull nut. The forming process comprises the following steps: cutting a wire to form a preset blank; shaping the preset blank; forming a preset head flange and a preset rod part of the shaped preset blank; inversely extruding a first inner hole in the preset head flange through a head fixed point of the preset head flange, and forming the preset rod part into a hexagonal rod; finishing the diameter of the preset head flange to form a head flange; inversely extruding a second inner hole in the hexagonal rod, and rounding a lower section of the hexagonal rod away from the head flange to form a second rod part; forming a chamfer at one end of the second rod part away from the head flange; and performing heat treatment, tapping, electroplating and glue coating on the preset semi-hexagonal pull nut with the second rod part formed with the chamfer to obtain a finished semi-hexagonal pull nut. The forming process of the semi-hexagonal pull nut can avoid the risk of poor hexagonal corner of the finished product, reduce the quality cost, shorten the over-molding time and improve the production efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of fastener forming, and particularly relates to a forming process and forming device of a semi-hexagonal pull nut and the semi-hexagonal pull nut. BACKGROUND

[0002] The pull nut, also known as a pull cap, is a nut that is fastened with a connected piece in the form of a pull cap and is widely used in the assembly of electromechanical and light industrial products such as automobiles, aviation, instruments, furniture, and decoration. It is developed to solve the problems of easy melting of welded nuts of metal thin plates and thin tubes and easy slipping of internal threads of the nuts. It does not need to tap internal threads and does not need to weld nuts, and is firmly riveted with high efficiency and is easy to use. In order to meet the needs of different models of battery boxes for new energy vehicles, a sealed blind hole pull nut is generally used to seal and connect the upper and lower cover plates of the battery box.

[0003] The sealed blind hole pull nut is a semi-hexagonal pull nut, which has a head flange, a first rod portion, and a second rod portion connected in sequence. The first rod portion is a hexagonal rod, and the second rod portion is a cylindrical rod. When the semi-hexagonal pull nut is produced using a cold heading process, the first inner hole of the head flange is counter-extruded in the third die station, and the first rod portion in the shape of a hexagon and the second rod portion in the shape of a cylinder are simultaneously formed. Then, the second inner hole communicated with the first inner hole is counter-extruded in the second rod portion end by the fourth die station, and the diameter of the head flange is finished by the fifth die station to obtain the finished semi-hexagonal pull nut. However, due to the continuous high-speed production of cold heading, the blank is over-molded from the third die station to the fifth die station, and the over-mold clamp is clamped on the cylindrical second rod portion. Therefore, the first rod portion cannot match the hexagonal die cavity of the next die cavity when the blank is over-molded twice to the next die cavity, and the hexagonal of the first rod portion is easily worn out. That is, the hexagonal corner problem occurs due to over-molding. As a result, the product has a high defective rate. In order to reduce the defective problem of the hexagonal corner, the over-molding speed is low, which also reduces the production efficiency. SUMMARY

[0004] In view of the problems in the prior art, the main purpose of the present application is to provide a forming process and forming device of a semi-hexagonal pull nut and the semi-hexagonal pull nut. The forming process of the semi-hexagonal pull nut simultaneously forms the rod body of the nut into a hexagonal rod in the third die station when counter-extruding the first inner hole. Then, the head flange is fine-extruded in the fourth die station, and finally, the lower section of the hexagonal rod away from the head flange is shrink-cylindrical to form a cylindrical second rod portion in the fifth die station to finally form the product structure. In this way, the risk of defective hexagonal corner can be avoided, the quality cost can be reduced, the over-molding time can be shortened, and the production efficiency can be improved.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] This invention provides a forming process for a semi-hexagonal rivet nut. The semi-hexagonal rivet nut includes a head flange, a first rod portion, and a second rod portion. The first rod portion is hexagonal, and the second rod portion is cylindrical. The rivet nut has an inner hole that passes through the head flange, the first rod portion, and the second rod portion along its axial direction. The process includes the following steps:

[0007] Cut the wire to form a pre-designed blank; shape the pre-designed blank;

[0008] The shaped blank is then formed into a pre-designed head and a pre-designed rod.

[0009] The preset head is extruded back through the first inner hole at a fixed point on its head to form the preset rod into a hexagonal rod;

[0010] The diameter of the preset head flange is adjusted to form the head flange;

[0011] The interior of the hexagonal rod is extruded back into the second inner hole, and the lower section of the hexagonal rod away from the head flange is rounded to form the second rod part;

[0012] The end of the second rod that is away from the head flange is chamfered.

[0013] The pre-formed semi-hexagonal rivet nut with chamfered second rod is heat-treated, tapped, electroplated, and coated with adhesive to obtain the finished semi-hexagonal rivet nut.

[0014] The present invention also provides a forming apparatus for a semi-hexagonal rivet nut, comprising a cold heading machine and a mold assembly mounted on the cold heading machine, the mold assembly comprising:

[0015] The first mold is used to shape the preset blank;

[0016] The second mold is used to form the pre-shaped pre-formed blank into a pre-shaped head flange and a pre-shaped rod.

[0017] The third mold is used to back-extract the first inner hole into the preset head flange and to form the preset rod into a hexagonal rod;

[0018] The fourth mold is used to refine the diameter of the preset head flange to form the head flange;

[0019] A fifth die, used to reverse-extrude the hexagonal rod into a second inner hole, the second inner hole communicating with the first inner hole, and the diameter of the second inner hole being smaller than the diameter of the first inner hole; and,

[0020] The lower section of the hexagonal rod, away from the head flange, is rounded and formed into a second rod portion;

[0021] A sixth mold, the sixth mold being used to form a chamfer at the end of the second rod that is away from the head flange.

[0022] As a further description of the above technical solution, the forming device also includes a shearing mechanism for cutting the wire into the preset blank.

[0023] As a further description of the above technical solution, the molding device also includes a feeding mechanism for feeding materials between multiple molds.

[0024] As a further description of the above technical solution, the feeding mechanism is a clamp.

[0025] As a further description of the above technical solution, the first mold, the second mold, the third mold, the fourth mold, the fifth mold and the sixth mold all include a main mold and a punch die corresponding to the main mold;

[0026] The main mold includes a main mold shell, a main mold pad, a main mold ejector pin, and a main mold core disposed within the main mold shell. The main mold core has an opening facing the main mold cavity of the punch, and the main mold ejector pin penetrates into the main mold cavity from the bottom of the main mold core.

[0027] The die includes a die shell, a die pad and a die ejector pin disposed within the die shell, one end of the die ejector pin being connected to the die pad, and the other end of the die ejector pin passing through the die shell and opposite to the main mold cavity.

[0028] As a further description of the above technical solution, the main cavity of the third mold and the fourth mold each has a first segment and a second segment connected to the first segment, wherein the first segment is a cylindrical cavity segment and the second segment is a hexagonal cavity segment.

[0029] The present invention also provides a semi-hexagonal rivet nut, comprising:

[0030] The head flange, the first rod portion, and the second rod portion are provided. The first rod portion is hexagonal, and the second rod portion is cylindrical.

[0031] The rivet nut has an inner hole that passes through the head flange, the first rod portion, and the second rod portion along its axial direction.

[0032] As a further description of the above technical solution, the inner hole includes:

[0033] A first inner hole penetrating the head flange and the first rod portion, and a second inner hole penetrating the first rod portion and the second rod portion; wherein,

[0034] The second inner hole is connected to the first inner hole, and the diameter of the second inner hole is smaller than the diameter of the first inner hole.

[0035] As a further description of the above technical solution, the end of the second rod away from the head flange is chamfered; the wall of the second inner hole is threaded.

[0036] In summary, the outstanding effects of this invention are:

[0037] The forming process of the semi-hexagonal rivet nut of the present invention involves back-extending the first inner hole at the third mold station of the forming device while forming the entire preset rod into a hexagonal rod. Then, at the fourth mold station, the head flange is precision upset. Next, at the fifth mold station, the lower section of the hexagonal rod away from the head flange is rounded to form a cylindrical second rod. At the sixth station, the end of the second rod is chamfered, and the preset product structure of the semi-hexagonal rivet nut is finally formed. This completely avoids the risk of poor hexagonal corners, reduces quality costs, and ensures excellent product quality.

[0038] The molding process of the semi-hexagonal rivet nut of the present invention no longer needs to consider the risk of hexagonal corners due to improper molding, which shortens the molding time and improves production efficiency. According to uncertainty assessment, the speed can be increased from 100 pieces per minute per machine to 135 pieces per minute per machine, which is more suitable for mass production. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a cold-forged product drawing of a semi-hexagonal rivet nut according to an embodiment of the present invention;

[0041] Figure 2 This is a finished product drawing of the semi-hexagonal rivet nut in an embodiment of the present invention;

[0042] Figure 3 This is a partial workstation diagram of the cold heading process for a semi-hexagonal rivet nut in an embodiment of the present invention;

[0043] Explanation of icon numbers:

[0044] 1. Semi-hexagonal rivet nut; 11. Head flange; 12. First rod; 13. Second rod; 14. First inner hole; 15. Second inner hole; 16. Thread; 17. Chamfer; 2. Pre-cast blank; 21. Hexagonal rod. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] In the description of this invention, it should be noted that the terms "upper," "middle," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0047] The following is in conjunction with the appendix Figure 1 To be continued Figure 3 The specific details of the examples and embodiments are described below.

[0048] This embodiment provides a forming process for a semi-hexagonal rivet nut. The semi-hexagonal rivet nut 1 includes a head flange 11, a first rod portion 12, and a second rod portion 13. The first rod portion 12 is hexagonal, and the second rod portion 13 is cylindrical. The rivet nut has an inner hole that passes through the head flange 11, the first rod portion 12, and the second rod portion 13 along its axial direction. The process includes the following steps:

[0049] Cut the wire to form a pre-designed blank; shape the pre-designed blank 2;

[0050] The pre-shaped blank 2 is formed into a pre-shaped head flange 11 and a pre-shaped rod;

[0051] The preset head flange 11 is back-extruded through its head point into the first inner hole 14 to form the preset rod into a hexagonal rod 21;

[0052] The diameter of the preset head flange 11 is adjusted to form the head flange 11;

[0053] The interior of the hexagonal rod 21 is back-extruded into the second inner hole 15, and the lower section of the hexagonal rod 21 away from the head flange 11 is rounded to form the second rod portion 13;

[0054] The end of the second rod portion 13 away from the head flange 11 is chamfered 17;

[0055] The pre-formed semi-hexagonal rivet nut with chamfer 17 on the second rod 13 is heat-treated, tapped, electroplated and glued to obtain the finished semi-hexagonal rivet nut 1.

[0056] Using the above process, a multi-station cold heading forming machine is used to process the pre-set blank 2 through six molds and six punches, with a production speed of 135 pieces per minute. First, the wire is cut and formed into the pre-set blank 2, and the pre-set blank 2 is shaped. Second, the pre-set head flange 11 and the pre-set rod are formed by the second mold. During this process, the punching pin in the second mold pre-forms the head at the fixed point in the main mold cavity. Then, the punching pin in the third mold will push the pre-set head flange 11 back into the first inner hole 14, thereby forming the first inner hole 14. At the same time, the pre-set rod is formed into a hexagonal rod 21 in the main mold cavity. The initial head flange 11 has a small diameter, which is refined by the fourth mold to increase its diameter and shorten its height, forming a head flange 11 with a diameter that meets actual requirements in a single step. Next, the fifth mold back-extrudes the interior of the hexagonal rod 21 into the second inner hole 15. Simultaneously, the lower section of the hexagonal rod 21, away from the head flange 11, is compressed into a cylindrical shape within its main mold cavity, forming the second rod portion 13 that meets actual requirements. The upper section, connected to the head flange 11, retains its hexagonal shape, becoming the first rod portion 12 that meets actual requirements. The length ratio and outer diameter ratio of the first rod portion 12 and the second rod portion 13 can be set according to actual needs. Finally, the sixth mold forms a chamfer 17 at the end of the formed second rod portion 13, the angle of which can be set according to actual needs. The pre-formed semi-hexagonal rivet nut obtained by cold heading undergoes necessary heat treatment, tapping, electroplating, and gluing processes to obtain the finished semi-hexagonal rivet nut 1. Therefore, during the cold heading process, in the two passes of the billet from the third mold to the fifth mold, since the preset rods are all full-length hexagonal rods 21, on the one hand, the clamping stability is high when clamping the opposite sides of the hexagon, and on the other hand, the billet will no longer be mismatched with the mold cavity when placed into the next mold cavity due to the clamping of round rods. Thus, the risk of hexagonal corners caused by improper mold passing is avoided, reducing the defect rate of hexagonal corners to 0%, thereby reducing quality costs. The speed can also be increased accordingly during mold passing, thereby improving the overall production efficiency. According to uncertainty assessment, the speed can be increased from 100 pieces per minute per machine to 135 pieces per minute per machine, which is more suitable for mass production.

[0057] Specifically, in this embodiment, the forming device for the semi-hexagonal rivet nut 1 includes a cold heading machine (not shown in the figure) and a mold assembly (not shown in the figure) mounted on the cold heading machine. The mold assembly includes:

[0058] The first mold is used to shape the preset blank 2;

[0059] The second mold is used to form the pre-shaped blank 2 into a pre-shaped head flange 11 and a pre-shaped rod.

[0060] The third mold is used to back-extrude into the preset head flange 11 as follows: Figure 3 The first inner hole 14 shown, and the preset rod portion are formed into an insert. Figure 3 The hexagonal rod 21 shown;

[0061] The fourth mold is used to refine the diameter of the preset head flange 11, forming an insert. Figure 3 The head flange 11 is shown;

[0062] The fifth die, used to reverse-extrude the hexagonal rod 21 as follows: Figures 1 to 3 The second inner hole 15 shown communicates with the first inner hole 14, and the diameter of the second inner hole 15 is smaller than the diameter of the first inner hole 14; and,

[0063] The lower section of the hexagonal rod 21, away from the head flange 11, is shaped as follows: Figures 1 to 3 The second rod portion 13 is shown;

[0064] The sixth mold, used to shape the end of the second rod portion 13 away from the head flange 11 as follows: Figure 1 and Figure 2 The chamfer is shown as 17.

[0065] Specifically, in this embodiment, the forming device further includes a shearing mechanism (not shown in the figure), which is used to cut the wire into the following shapes: Figure 3 The preset blank 2 shown.

[0066] Specifically, in this embodiment, the molding device further includes a feeding mechanism (not shown in the figure), which is used to feed materials between multiple molds.

[0067] Specifically, in this embodiment, the feeding mechanism is a clamp. The clamp moves between the various molds to feed materials.

[0068] Specifically, in this embodiment, the first mold, the second mold, the third mold, the fourth mold, the fifth mold, and the sixth mold all include a main mold (not shown in the figure) and a punch (not shown in the figure) corresponding to the main mold;

[0069] The main mold includes a main mold shell, a main mold pad, a main mold ejector pin, and a main mold core disposed within the main mold shell. The main mold core has an opening facing the main mold cavity of the punch, and the main mold ejector pin penetrates into the main mold cavity from the bottom of the main mold core.

[0070] The die includes a die shell, a die pad and a die ejector pin disposed within the die shell, one end of the die ejector pin being connected to the die pad, and the other end of the die ejector pin passing through the die shell and opposite to the main mold cavity.

[0071] Specifically, in this embodiment, the main cavity of the third mold and the fourth mold each has a first section and a second section connected to the first section. The first section is a cylindrical cavity section, which is adapted to the front and rear of the head flange 11 for finishing. The second section is a hexagonal cavity section, which is adapted to the preset hexagonal rod of the whole section.

[0072] Please see Figure 2 Specifically, the semi-hexagonal rivet nut 1 provided in this embodiment includes a head flange 11, a first rod portion 12, and a second rod portion 13. The first rod portion 12 is hexagonal, and the second rod portion 13 is cylindrical. The rivet nut has an inner hole that passes through the head flange 11, the first rod portion 12, and the second rod portion 13 along its axial direction. The inner hole includes a first inner hole 14 and a second inner hole 15 that are connected. The first inner hole 14 passes through the head flange 11 and the portion of the first rod portion 12, and the second inner hole 15 passes through the portion of the first rod portion 12 and the second rod portion 13. The diameter of the second inner hole 15 is smaller than the diameter of the first inner hole 14, and the hole wall of the second inner hole 15 is formed with threads 16 by tapping. The end of the second rod portion 13 (i.e., the end of the second rod portion 13 away from the head flange 11) is also formed with a chamfer 17, the size of which can be set according to actual needs.

[0073] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any changes, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A forming process of a semi-hexagon socket head cap screw, the semi-hexagon socket head cap screw comprising a head flange, a first shank portion and a second shank portion, the first shank portion being hexagonal, the second shank portion being a cylindrical shank, the socket head cap screw being provided with an inner bore through the head flange, the first shank portion and the second shank portion in the axial direction thereof, characterized in that, The method comprises the following steps: cutting the wire into a preset blank; shaping the preset blank; forming a preset head flange and a preset rod part from the shaped preset blank; back-extruding a first inner hole in the preset head flange through the head of the preset head flange, and forming a hexagonal rod from the preset rod part; finishing the diameter of the preset head flange to form a head flange; back-extruding a second inner hole in the hexagonal rod, and rounding the lower section of the hexagonal rod away from the head flange to form a second rod part; forming a chamfer on the end of the second rod part away from the head flange; 2. A forming device for a semi-hexagon thin shoulder pull-up nut, characterized by performing heat treatment, tapping, electroplating and rubber coating on the preset half hexagon rivet nut with the chamfered second rod part to obtain a finished half hexagon rivet nut. The cold header comprises a mold assembly installed on the cold header, and the mold assembly comprises: a first mold for shaping a preset blank; a second mold for forming a preset head flange and a preset rod part from the shaped preset blank; a third mold for back-extruding a first inner hole in the preset head flange and forming a hexagonal rod from the preset rod part; a fourth mold for finishing the diameter of the preset head flange to form a head flange; a fifth mold for back-extruding a second inner hole in the hexagonal rod, the second inner hole being in communication with the first inner hole and having a smaller diameter than the first inner hole; and rounding the lower section of the hexagonal rod away from the head flange to form a second rod part; 3. The apparatus for forming a semi-hexagon thin rivet nut according to claim 2, wherein a sixth mold for forming a chamfer on the end of the second rod part away from the head flange.

4. The apparatus for forming a semi-hexagon thin riv nut of claim 2, wherein, The forming device further comprises a shearing mechanism for shearing the wire into the preset blank.

5. The apparatus for forming a semi-hexagon thin rivet nut according to claim 4, wherein The forming device further comprises a feeding mechanism for feeding between the molds.

6. The apparatus for forming a semi-hexagon thin riv nut of claim 2, wherein, The feeding mechanism is a clamp. The first mold, the second mold, the third mold, the fourth mold, the fifth mold and the sixth mold each comprise a main mold and a punch mold corresponding to the main mold; The main mold comprises a main mold shell, a main mold pad, a main mold plunger and a main mold core provided in the main mold shell, the main mold core having a main mold cavity with an opening facing the punch mold, and the main mold plunger penetrating into the main mold cavity from the bottom of the main mold core; 7. The apparatus for forming a semi-hexagon thin rivet nut according to claim 6, wherein The punch mold comprises a punch mold shell, a punch mold pad and a punch mold plunger provided in the punch mold shell, one end of the punch mold plunger being connected to the punch mold pad, and the other end of the punch mold plunger penetrating out of the punch mold shell and facing the main mold cavity. The main mold cavities of the third mold and the fourth mold each have a first section and a second section connected to the first section, wherein the first section is a cylindrical cavity section, and the second section is a hexagonal cavity section.

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