A cold heading device for forming rivet nuts, a cold heading process and rivet nuts

Abstract

The present invention discloses a cold heading device for forming a rivet nut, comprising a cold heading machine and a die assembly installed on the cold heading machine, wherein the die assembly comprises: a first die, the first die is used to form a preset head on the upper part of a preset blank; a second die, the second die is used to form a head fixed point in the preset head, and to form a step portion between the preset head and the lower part of the preset blank; a third die, the third die is used to reversely extrude a first inner hole in the preset head and the step portion; a fourth die, the fourth die is used to form a flange portion in the preset head, and to form a flower tooth in the step portion; the flange portion comprises a groove under the head; and a fifth die is used to reversely extrude a second inner hole in the lower part of the preset blank. The rivet nut made by the cold heading device can ensure sealing performance and minimum torque attenuation in a limited space.

Description

Technical Field

[0001] The invention relates to the field of fastener manufacturing, and in particular to a cold heading device and a cold heading process for forming a rivet nut, and the manufactured rivet nut. Background Art

[0002] The pull rivet nut is a nut that is fastened to the connected parts by pulling rivets. It is currently widely used in the assembly of electromechanical and light industrial products such as automobiles, aviation, instruments, furniture, and decoration. It was developed to solve the shortcomings of easy melting of welding nuts on metal sheets and thin tubes and easy slipping of tapping internal threads. It does not require tapping internal threads, does not require welding nuts, has a strong riveting efficiency, and is easy to use.

[0003] However, for some small-sized rivet nuts, their sealing performance is poor during use. For some occasions with high requirements for sealing performance, their sealing effect often cannot meet the use requirements. In order to solve the sealing problem, the existing methods are: 1. Applying glue to the entire underside of the rivet nut head. This method will cause the torque attenuation of the rivet nut, so that the sealing performance and torque resistance of the rivet nut cannot be guaranteed; 2. Adding an O-ring to the rivet nut, but due to the small overall size of the rivet nut, the O-ring is difficult to process, the cost is high, and it needs to be manually installed, which is inefficient. Summary of the invention

[0004] The object of the present invention is to provide a cold heading device for forming rivet nuts. The rivet nuts made by using the cold heading device can ensure sealing performance and minimum torque attenuation in a limited space.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a cold heading device for forming rivet nuts, including a cold heading machine and a mold assembly installed on the cold heading machine, wherein the mold assembly includes:

[0006] A first die, wherein the first die is used to form a preset head on the upper portion of the preset blank;

[0007] A second mold, the second mold is used to form a head fixed point in the preset head and to form a step portion between the preset head and the lower portion of the preset blank;

[0008] A third die, the third die is used for reversely extruding a first inner hole in the preset head and the step portion;

[0009] A fourth mold, the fourth mold is used to form a flange portion on the preset head portion and to form flower teeth on the step portion; the flange portion includes a groove under the head;

[0010] A fifth die is used to reversely extrude a second inner hole in the lower portion of the preset blank; the second inner hole is communicated with the first inner hole, and the diameter of the second inner hole is smaller than the diameter of the first inner hole.

[0011] In the above technical solution, the first mold, the second mold, the third mold, the fourth mold and the fifth mold all include a main mold and a punching die that are arranged accordingly;

[0012] The main mold comprises a main mold shell, a main mold cushion block, a main mold ejector pin and a main mold core arranged in the main mold shell, the main mold core has a main mold cavity opening toward the punching die, and the main mold ejector pin penetrates into the main mold cavity from the bottom of the main mold core;

[0013] The die comprises a die shell, a die pad and a die ejector arranged in the die shell, one end of the die ejector is connected to the die pad, and the other end of the die ejector passes through the die shell and faces the main die cavity.

[0014] In the above technical solution, the fourth mold includes a first spring, and the first spring is arranged between the die ejector pin and the die cushion block. When the die ejector pin abuts against the first inner hole, the first spring is in a compressed state.

[0015] In the above technical solution, the dies of the third die, the fourth die and the fifth die further include a die ejector pin arranged in the die shell and an ejector sleeve sleeved on the die ejector pin.

[0016] In the above technical solution, the first mold includes a second spring, the second spring is arranged between the main mold cushion block and the main mold core, and the second spring is in a compressed state when the punch ejector pin is under pressure.

[0017] A cold heading process for forming a rivet nut, comprising:

[0018] Cut the wire to form a preset blank;

[0019] The preset blank is cold headed to form a preset rivet nut with a groove under the head;

[0020] Glue is applied to the groove under the head to form a rivet nut.

[0021] In the above technical solution, “cold heading the preset blank to form a preset rivet nut with a groove under the head” specifically includes:

[0022] Forming the preset blank into a preset head;

[0023] The head is fixed in the preset head, and a step is formed between the preset head and the lower part of the preset blank;

[0024] Extruding the preset head and the step portion into a first inner hole;

[0025] Forming a flange portion on the preset head and forming flower teeth on the step portion;

[0026] The lower portion of the preset blank is reversely extruded into the second inner hole to form a preset rivet nut.

[0027] In the above technical solution, the preset rivet nut needs to be heat treated, tapped and electroplated before gluing.

[0028] A rivet nut, wherein the flange portion of the rivet nut is provided with a sub-head groove, and sealant is arranged in the sub-head groove.

[0029] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0030] 1. In the present invention, the rivet nuts are manufactured by cold heading process, which greatly enhances the strength of the product, reduces the production cost and improves the production efficiency.

[0031] 2. The fourth mold is used to form a flange part of the preset head, and the flange part includes a groove under the head. By applying glue in the groove under the head, the formed small-sized rivet nut can be used in a limited space while ensuring its sealing performance and minimum torque attenuation, so as to ensure its safety and stability after assembly and meet the higher performance requirements of the product.

[0032] 3. The fourth mold includes a first spring, which is arranged between the die ejector pin and the die pad, so that when the step portion is formed with flower teeth, the die ejector pin can be used to protect the first inner hole to prevent it from deformation and ensure the accuracy after processing.

[0033] 4. In the second die, a step portion is formed between the preset head and the lower portion of the preset blank, and a certain large-diameter step is made in advance to prevent the gap when forming the flower tooth blank diameter from being too large when the flower teeth are bundled, causing the first inner hole wall thickness to be insufficient and concave. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the structure of the rivet nut in the present invention;

[0035] Figure 2 is a schematic diagram of a mold assembly in the present invention;

[0036] Figure 3 This is a diagram of the forming process of the rivet nut in the present invention;

[0037] Figure 4 It is a schematic diagram of the fourth mold structure in the present invention;

[0038] Figure 5It is a schematic diagram of the first mold structure in the present invention.

[0039] Among them: 1. the first mold; 2. the second mold; 3. the third mold; 4. the fourth mold; 5. the fifth mold; 11. the main mold; 111. the main mold shell; 112. the main mold pad; 113. the main mold ejector; 114. the main mold core; 115. the second spring; 12. the die; 121. the die shell; 122. the die pad; 123. the die ejector; 124. the first spring; 125. the die ejector rod; 126. the ejector sleeve; 6. the rivet nut; 61. the preset blank; 62. the preset head; 63. the head fixed point; 64. the step portion; 65. the first inner hole; 66. the flange portion; 67. the groove under the head; 68. the flower teeth; 69. the second inner hole. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0041] Example 1: See Figures 1 to 5 As shown, a cold heading device for forming a rivet nut comprises a cold heading machine and a die assembly mounted on the cold heading machine, wherein the die assembly comprises:

[0042] A first mold 1, wherein the first mold 1 is used to form a preset head 62 on the upper portion of a preset blank 61;

[0043] A second mold 2, the second mold 2 is used to form a head fixed point 63 in the preset head 62, and to form a step portion 64 between the preset head 62 and the lower portion of the preset blank 61;

[0044] A third die 3, the third die 3 is used for reversely extruding a first inner hole 65 inside the preset head 62 and the step portion 64;

[0045] A fourth mold 4, the fourth mold 4 is used to form a flange portion 66 on the preset head portion 62, and to form a flower tooth 68 on the step portion 64; the flange portion 66 includes a lower groove 67;

[0046] The fifth mold 5 is used to reversely extrude the second inner hole 69 in the lower part of the preset blank 61; the second inner hole 69 is communicated with the first inner hole 65, and the diameter of the second inner hole 69 is smaller than the diameter of the first inner hole 65.

[0047] The fourth die 4 of the cold heading device can form a flange portion 66, and the flange portion 66 includes a sub-head groove 67. By designing the shape and size of the special sub-head groove 67 and coordinating the glue coating control, the sealing performance and minimum torque attenuation can be guaranteed, especially for small-sized rivet nuts 6, under the premise that the product assembly size design cannot be changed, so as to ensure its safety and stability after assembly and meet the higher performance requirements of the product.

[0048] The cold heading device also includes a transfer device, which can be a clamp, and the clamp is used to move the material between the various molds. The mold assembly is assembled on the cold heading machine, and the first mold 1, the second mold 2, the third mold 3, the fourth mold 4 and the punch 12 in the fifth mold 5 move as a whole, and the punch ejector 123 pushes the workpiece to be processed into the main mold cavity, and according to the principle of plastic deformation of the material, it is formed into a preset shape and size in the main mold cavity.

[0049] See also Figure 2 As shown, the first mold 1, the second mold 2, the third mold 3, the fourth mold 4 and the fifth mold 5 all include a main mold 11 and a punching die 12 that are correspondingly arranged;

[0050] The main mold 11 includes a main mold shell 111, a main mold cushion block 112, a main mold ejector pin 113 and a main mold core 114 disposed in the main mold shell 111, the main mold core 114 has a main mold cavity opening toward the punching die 12, and the main mold ejector pin 113 penetrates into the main mold cavity from the bottom of the main mold core 114;

[0051] The die 12 includes a die shell 121, a die pad 122 and a die ejector pin 123 disposed in the die shell 121, one end of the die ejector pin 123 is connected to the die pad 122, and the other end of the die ejector pin 123 passes through the die shell 121 and faces the main mold cavity.

[0052] In the fourth mold 4, the step portion 64 can be formed into a flower tooth 68. This process adopts a bundled flower tooth solution. In order to protect the first inner hole 65, the fourth mold 4 includes a first spring 124. The first spring 124 is arranged between the die ejector pin 123 and the die pad 122. When the flower tooth 68 is formed, the die ejector pin 123 is against the first inner hole 65. At this time, the first spring 124 is in a compressed state. Figure 4 shown.

[0053] See also Figure 2 As shown, the dies 12 of the third die 3, the fourth die 4 and the fifth die 5 further include a die ejector pin 125 disposed in the die shell 121 and an ejector sleeve 126 sleeved on the die ejector pin 123. The ejector sleeve 126 is used to protect the die ejector pin 123 and to separate the product from the die ejector pin 123 after molding.

[0054] See also Figure 5 As shown, in order to make the preset blank 61 be punched uniformly in the main mold cavity and improve the quality of the product, the first mold 1 includes a second spring 115, and the second spring 115 is arranged between the main mold pad 112 and the main mold core 114. When the die ejector pin 123 is pressed, due to the setting of the second spring 115, the die ejector pin 123 pushes the main mold 11 downward, and the preset blank 61 forms a preset head 62 in the main mold cavity.

[0055] A cold heading process for forming a rivet nut, characterized by comprising:

[0056] Cutting the wire to form a preset blank 61;

[0057] The preset blank 61 is cold headed to form a preset rivet nut having a groove 67 under the head;

[0058] Glue is applied to the groove 67 under the head to form the rivet nut 6.

[0059] The step of “cold heading the preset blank 61 to form a preset rivet nut having a recess 67 under the head” specifically includes:

[0060] Forming the preset blank 61 into a preset head 62;

[0061] A head fixed point 63 is formed in the preset head 62, and a step portion 64 is formed between the preset head 62 and the lower portion of the preset blank 61;

[0062] Extrude the preset head portion 62 and the step portion 64 into the first inner hole 65;

[0063] The preset head 62 is formed into a flange portion 66, and the step portion 64 is formed into a flower tooth 68;

[0064] The lower portion of the preset blank 61 is reversely extruded into the second inner hole to form a preset rivet nut.

[0065] Before gluing, the preset rivet nut needs to be heat treated, tapped and electroplated.

[0066] A rivet nut, wherein the flange portion 66 of the rivet nut has a sub-head groove 67, and a sealant is arranged in the sub-head groove 67.

[0067] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A cold heading device for forming rivet nuts, comprising a cold heading machine and a die assembly mounted on the cold heading machine, characterized in that: The mold assembly comprises: A first die, wherein the first die is used to form a preset head on the upper portion of the preset blank; A second mold, the second mold is used to form a head fixed point in the preset head and to form a step portion between the preset head and the lower portion of the preset blank; A third die, the third die is used for reversely extruding a first inner hole in the preset head and the step portion; A fourth mold, the fourth mold is used to form a flange portion on the preset head portion and to form flower teeth on the step portion; the flange portion includes a groove under the head; A fifth die is used to reversely extrude a second inner hole in the lower portion of the preset blank; the second inner hole is communicated with the first inner hole, and the diameter of the second inner hole is smaller than the diameter of the first inner hole.

2. The cold heading device for forming rivet nuts according to claim 1, characterized in that: The first mold, the second mold, the third mold, the fourth mold and the fifth mold all include a main mold and a punching die that are arranged accordingly; The main mold comprises a main mold shell, a main mold ejector pin and a main mold core arranged in the main mold shell, the main mold core has a main mold cavity opening toward the punching die, and the main mold ejector pin penetrates into the main mold cavity from the bottom of the main mold core; The die comprises a die shell, a die pad and a die ejector arranged in the die shell, one end of the die ejector is connected to the die pad, and the other end of the die ejector passes through the die shell and faces the main die cavity.

3. The cold heading device for forming rivet nuts according to claim 2, characterized in that: The fourth mold includes a first spring, which is arranged between the die ejector pin and the die cushion block. When the die ejector pin abuts against the first inner hole, the first spring is in a compressed state.

4. The cold heading device for forming rivet nuts according to claim 2, characterized in that: The punching dies of the third mold, the fourth mold and the fifth mold further include an ejector sleeve sleeved on the ejector pins of the punching dies.

5. The cold heading device for forming rivet nuts according to claim 2, characterized in that: The first mold includes a second spring and a main mold cushion block, the second spring is arranged between the main mold cushion block and the main mold core, and the second spring is in a compressed state when the punch ejector pin is pressed.

6. A cold heading process for forming rivet nuts, characterized in that: include: Cut the wire to form a preset blank; The preset blank is cold headed to form a preset rivet nut with a groove under the head; Applying glue to the groove under the head to form a rivet nut; The step of "cold heading the preset blank to form a preset rivet nut having a groove under the head" specifically includes: Forming the preset blank into a preset head; The head is fixed in the preset head, and a step is formed between the preset head and the lower part of the preset blank; Extruding the preset head and the step portion into a first inner hole; Forming a flange portion on the preset head and forming flower teeth on the step portion; The lower portion of the preset blank is reversely extruded into the second inner hole to form a preset rivet nut.

7. The cold heading process for forming rivet nuts according to claim 6, characterized in that: Before gluing, the preset rivet nut needs to be heat treated, tapped and electroplated.

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