Extrusion type self-tapping nut preparation process, extrusion type self-tapping nut and application of extrusion type self-tapping nut

Abstract

The invention discloses an extrusion type self-tapping nut preparation technology, an extrusion type self-tapping nut and application of the extrusion type self-tapping nut. In the thread machining procedure of the extrusion type self-tapping nut preparation technology, extrusion plastic deformation is conducted on a through hole of a nut through an extrusion tool with a thread form; and therefore, the wall surface of the through hole is extruded into a thread of which the metal fiber tissue is a continuous fiber tissue, and an internal threaded hole is correspondingly obtained. According to the extrusion type self-tapping nut, the extrusion threads are formed on the extrusion type self-tapping nut through extrusion plastic deformation, so that the extrusion type self-tapping nut has the advantage of low material loss, the metal fiber tissues of the extrusion threads are continuous and are not cut off, the strength of the threads is improved, and therefore the tapping quality of the extrusion type self-tapping nut on an external connecting piece is effectively improved. According to the extrusion type self-tapping nut, the cold hardening phenomenon caused by extrusion of the extrusion threads can be avoided, the abrasion resistance of the surfaces of the threads can be improved, the extrusion type self-tapping nut is in complete contact with the surface of an external connecting piece, and therefore the possibility of vibration loosening can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of fastener preparation, and in particular to a preparation process of an extruded self-tapping nut, an extruded self-tapping nut and applications thereof. Background Art

[0002] Self-tapping nuts are special nuts with sharp tooth profiles that allow them to be screwed directly into connected parts, eliminating the need for pre-machined matching threads on the parts, as is the case with conventional nuts. During tightening, the nut's sharp tooth profile exerts extrusion and cutting forces on the surface of the material being connected. As the nut rotates, it gradually forms internal threads that match its own, creating a secure connection with the bolt or screw. This unique installation method has led to its widespread use in electronic equipment assembly, automotive component connections, and furniture manufacturing, facilitating the rapid assembly of various products.

[0003] The self-tapping threads of the self-tapping nuts currently on the market are cut threads. This type of cut thread is mainly formed by the rotary cutting of the tap of the tapping machine. This processing method has obvious disadvantages: on the one hand, a large amount of debris will be generated during the tap cutting process, resulting in material waste; on the other hand, since the cutting operation will cut off the metal fiber tissue, the overall strength of the self-tapping nut will be greatly reduced, affecting its performance and connection reliability. When self-tapping nuts are used in scenarios such as automotive driving systems and aerospace equipment that have extremely high requirements for component strength, the cut metal fiber tissue may cause the nut to loosen or break under complex working conditions such as vibration and impact, thereby causing serious safety hazards. In addition, the processing process of cutting threads is relatively complicated and requires multiple cutting and trimming, which not only reduces production efficiency, but also increases equipment wear and maintenance costs.

[0004] Therefore, in view of the shortcomings of the existing technology, it is necessary to provide an extruded self-drilling nut preparation process, an extruded self-drilling nut and its application to solve the shortcomings of the existing technology. Summary of the Invention

[0005] The first object of the present invention is to avoid the shortcomings of the prior art and provide a process for preparing an extruded self-drilling nut. The process for preparing an extruded self-drilling nut forms a thread by plastic deformation through extrusion, thereby having the advantages of low material loss and improved thread strength.

[0006] The above-mentioned purpose of the present invention is achieved through the following technical measures: A process for preparing extruded self-drilling nuts is provided. In the thread processing step, an extrusion tool with a thread profile is used to extrude plastic deformation on the nut through hole, so that the through hole wall is extruded into a thread in which the metal fiber structure is a continuous fiber structure, thereby obtaining an internal threaded hole.

[0007] Preferably, the extrusion type self-tapping nut is provided with a flange and a main body, and the flange is integrally connected to the lower bottom surface of the main body.

[0008] Preferably, the main body is provided with a circular through hole.

[0009] In the thread processing step, the extrusion tool is rotated and screwed into the interior of the circular through hole from one side of the flange, and the inner wall surface of the circular through hole is extruded to form the internal threaded hole.

[0010] During the forging process, a chip collecting groove is formed on the surface of the flange, which is concave in the direction of the main body, and the chip collecting groove is connected to the through hole. Preferably, the chip collecting groove is used to accommodate the chips generated when the external connection piece is self-drilled.

[0011] Preferably, the threads in the above-mentioned internal threaded hole are divided into standard teeth, guide teeth, first self-tapping teeth and second self-tapping teeth. The standard teeth, the second self-tapping teeth, the first self-tapping teeth and the guide teeth are arranged in sequence from top to bottom, and the chip collecting groove is located at the lower part of the guide teeth.

[0012] The crest height of the standard thread is defined as H1, the crest height of the second self-tapping thread is defined as H2, the crest height of the first self-tapping thread is defined as H3, and the crest height of the guide thread is defined as H4. H1>H2>H3>H4 exists.

[0013] Preferably, the minor diameter value of the above-mentioned standard thread is equal to the minor diameter value of the second self-tapping thread.

[0014] Preferably, the minor diameter value of the first self-tapping thread and the minor diameter value of the guide thread are both smaller than the minor diameter value of the standard thread.

[0015] Another object of the present invention is to provide an extruded self-drilling nut that avoids the shortcomings of the prior art and has the advantages of low material loss and improved thread strength.

[0016] The above-mentioned purpose of the present invention is achieved through the following technical measures: Provided is an extruded self-tapping nut, which is prepared by the above-mentioned extruded self-tapping nut preparation process.

[0017] The third object of the present invention is to avoid the shortcomings of the prior art and provide an application of an extruded self-tapping nut, which can quickly tap external connectors based on the high strength of the thread of the extruded self-tapping nut.

[0018] The above-mentioned purpose of the present invention is achieved through the following technical measures: Provided is an application of an extruded self-tapping nut, wherein the extruded self-tapping nut is obtained by adopting the above-mentioned extruded self-tapping nut preparation process and is used to self-drill a cylindrical pin to form a fastener.

[0019] A fourth object of the present invention is to avoid the deficiencies of the prior art and provide an application of an extruded self-tapping nut in an automobile grounding device, wherein the application is based on the high thread strength of the extruded self-tapping nut so as to quickly tap external connectors.

[0020] The above-mentioned purpose of the present invention is achieved through the following technical measures: Provided is an application of an extruded self-tapping nut in an automobile grounding device. The extruded self-tapping nut is obtained by adopting the above-mentioned extruded self-tapping nut preparation process and is used as a nut in the automobile grounding device.

[0021] The present invention provides a process for preparing an extruded self-drilling nut, an extruded self-drilling nut and its application, wherein in the thread processing step, the extruded self-drilling nut preparation process uses an extrusion tool with a thread profile to extrude plastic deformation on the through hole of the nut, thereby extruding the wall of the through hole into a thread with a metal fiber structure as a continuous fiber structure, corresponding to an internal threaded hole. The present invention forms an extruded thread on the extruded self-drilling nut through extrusion plastic deformation, so that the extruded self-drilling nut has the advantage of low material loss, and the metal fiber structure of the extruded thread is continuous and not cut off, and the strength of the thread is improved, thereby effectively improving the tapping of the extruded self-drilling nut on the external connection. In addition, the extruded thread of the present invention undergoes cold work hardening caused by extrusion, thereby significantly improving the wear resistance of the thread surface. The extruded self-drilling nut is in full contact with the surface of the external connection, thereby reducing the possibility of vibration loosening. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is further described with reference to the accompanying drawings, but the contents in the accompanying drawings do not constitute any limitation to the present invention.

[0023] Figure 1 The structural diagram of the thread processing process for the preparation process of extruded self-tapping nuts.

[0024] Figure 2 This is a schematic diagram of the structure of an extruded self-tapping nut after the forging process.

[0025] Figure 3 This is a cross-sectional view of an extruded self-tapping nut.

[0026] Figure 4 This is an exploded diagram of the vehicle grounding system.

[0027] exist Figures 1 to 4 Including: Extrusion type self-tapping nut 10, Main body 100, internal thread hole 110, standard thread 120, guide thread 130, second self-tapping thread 140, first self-tapping thread 150, Flange 200 and chip collecting groove 210.

[0028] Connecting pin 20, Ground terminal 30, External fixing surface 40, Extrusion tool 50. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described with reference to the following examples.

[0030] Example 1: A process for preparing an extruded self-drilling nut, such as Figure 1 As shown, in the thread processing step, the nut through hole is extruded and plastically deformed by an extrusion tool 50 with a thread profile, so that the through hole wall is extruded into a thread in which the metal fiber structure is a continuous fiber structure, corresponding to the internal threaded hole 110.

[0031] The core hole cross section of the extrusion self-tapping nut 10 of the present invention is circular, which can reduce the driving torque, specifically reduce friction, provide uniform guidance and facilitate material flow.

[0032] The metal fiber structure of the extruded self-tapping nut 10 of the present invention is continuous and not cut during the thread extrusion process, so the strength of the thread is improved, so the extruded thread is usually about 30% stronger than the cut thread. This thread undergoes cold work hardening due to extrusion, so the surface hardness of the extruded thread can be increased by 40%-50% compared to the core; therefore, the extruded thread of the extruded self-tapping nut 10 of the present invention has the advantages of high surface wear resistance and high strength. Moreover, the surface finish of the extruded thread is high, which is beneficial to improving the fitting accuracy and sealing of the thread, and is also more conducive to the assembly of the thread. Since the internal thread of the extruded self-tapping nut 10 of the present invention is an extruded thread, the extruded self-tapping nut 10 has the advantage of low material loss.

[0033] It should be noted that the invention focuses on the thread processing process. The nut of the present invention can be made using current conventional processes, such as smelting and forging, annealing and cold forging to obtain common flange nuts.

[0034] The extrusion type self-tapping nut 10 is provided with a flange 200 and a main body 100. The flange 200 is integrally connected to the lower bottom surface of the main body 100; the main body 100 is provided with a circular through hole.

[0035] The plane where the flange 200 in the extrusion type self-tapping nut 10 is located is used as a reference surface, and the reference surface is defined as the lower bottom surface of the extrusion type self-tapping nut 10 .

[0036] In the thread processing step, the extrusion tool 50 is rotated and screwed into the circular through hole from one side of the flange 200 and extrudes the inner wall surface of the circular through hole, thereby forming the internal thread hole 110 .

[0037] During the forging process, a chip collecting groove 210 is formed on the surface of the flange 200 and is concave in the direction of the main body 100, and the chip collecting groove 210 is connected to the through hole. Figure 2 As shown; the chip collecting groove 210 is used to accommodate the chips generated when the external connecting member is self-drilled.

[0038] It should be noted that the chip collecting groove 210 of the present invention is used to accommodate the extruded self-tapping nut 10 and generate chips when tapping the external connector, so as to prevent the chips from having nowhere to be accommodated or discharged and affecting the connection between the extruded self-tapping nut 10 and the external connector.

[0039] During the forging process of the flange 200, a circular chip groove 210 is formed on the surface of the flange 200. The center of the chip groove 210 is located at the central axis of the internally threaded hole 110. In any longitudinal cross-section of the extruded self-tapping nut 10, the diameter of the chip groove 210 increases from top to bottom, and the upper portion of the chip groove 210 communicates with the internally threaded hole 110. It should be noted that the shape of the chip groove 210 of the present invention facilitates the downward discharge of residual chips.

[0040] The extrusion tool 50 is inserted into the extrusion type self-tapping nut 10 and screwed into the circular through hole. Figure 1 In the direction shown, the minor diameter of the thread profile of the extrusion tool 50 of the present invention increases from top to bottom, thereby increasing the minor diameter of the internal threaded hole 110 from top to bottom. The major diameters of the thread profiles of the extrusion tool 50 are all equal, or the major diameters of the thread profiles of the extrusion tool 50 increase from top to bottom.

[0041] It should be noted that the purpose of the minor diameter of the internal threaded hole 110 increasing from the top to the bottom is to facilitate the extrusion type self-tapping nut 10 to enter the external connecting piece and to facilitate the discharge of debris downward.

[0042] like Figure 3 As shown, the threads in the internal threaded hole 110 are divided into standard teeth 120, guide teeth 130, first self-tapping teeth 140 and second self-tapping teeth 150. The standard teeth 120, second self-tapping teeth 150, first self-tapping teeth 140 and guide teeth 130 are arranged in sequence from top to bottom, and the chip collecting groove 210 is located at the lower part of the guide teeth 130.

[0043] It should be noted that the function of the guide teeth 130 of the present invention is to align the coaxiality with the external connection piece to be self-tapped through the gap, to perform the initial positioning of the extrusion type self-tapping nut, and to avoid the thread from being screwed in. The function of the first self-tapping tooth 140 is to invade the surface of the external connection piece to be self-tapped. As the nut rotates, the thread tooth side continues to squeeze the external connection piece to be self-tapped, forcing the external connection piece to be self-tapped to accumulate in the direction of the tooth valley, forming the prototype of the external thread. The function of the second self-tapping tooth 150 is to enhance the extrusion effect through the fine point tooth shape, increase the external thread tooth height to close to the standard tooth 120 height, compact the thread side wall and correct the accuracy. The function of the standard tooth 120 is to finally extrude the external connection piece to be self-tapped to form a standard external thread. The external thread in the standard tooth 120 area is fully engaged to achieve high-precision matching. The extrusion type self-tapping nut of the present invention utilizes the differentiated design of the segmented internal thread when screwed into the external connection piece to be self-tapped, and extrudes the external thread on the surface of the external connection piece to be self-tapped to achieve engagement and locking. Its core innovation lies in the division of standard teeth 120, guide teeth 130, first self-tapping teeth 140, second self-tapping teeth 150 and chip groove 210, which successively solve the problems of debris collection, guiding and centering, and staged progressive extrusion thread forming.

[0044] The crest height of the standard thread 120 is defined as H1, the crest height of the second self-tapping thread 150 is defined as H2, the crest height of the first self-tapping thread 140 is defined as H3, and the crest height of the guide thread 130 is defined as H4. H1>H2>H3>H4. The minor diameter of the standard thread 120 and the minor diameter of the second self-tapping thread 140 are equal; the minor diameters of the first self-tapping thread 140 and the guide thread are both smaller than the minor diameter of the standard thread.

[0045] The minimum value of the standard internal thread diameter in the standard nut is defined as D 标准1min The standard internal thread diameter value in the standard nut is defined as D 标准 , define the outer diameter of the external connection piece to be self-tapped as D, define the minor diameter value of the standard tooth 120 as d1, define the minor diameter value of the second self-tapping tooth 150 as d2, define the minor diameter value of the first self-tapping tooth 140 as d3, and define the minor diameter value of the guide tooth 130 as d4. 1max <d4<1.2D,D 1max <d3<D, d2=d1=D 标准 The standard nut height is defined as H 标准 , there exists H1=H 标准 , 0.8H 标准 <H2<H 标准 , 0.6H 标准 <H3<0.8H 标准 , 0.3H 标准 <H4<0.6H 标准 .

[0046] The tapping angles of the standard thread 120, the second self-tapping thread 150, the first self-tapping thread 140, and the guide thread 130 are all 60°. The pitch of the standard thread 120, the second self-tapping thread 150, the first self-tapping thread 140, and the guide thread 130 are all equal to the standard thread pitch of a standard nut.

[0047] The inner chamfer diameter of the chip collecting groove 210 is defined as d a , the minimum value of the standard inner chamfer diameter in the standard nut is defined as d 标准min , the maximum value of the standard inner chamfer diameter in the standard nut is defined as d 标准max , there exists 1.2d 标准min <d a <1.2d 标准max ; Standard nuts include M3, M4, M5, M6, M7, M8, M10, M12, M14, M16, M18, or M20. The standard thread pitch and internal thread minor diameter of standard nuts shall comply with GB / T 15756:2008; the standard crest height of standard nuts shall comply with ISO 68-1; and the standard internal chamfer diameter of standard nuts shall comply with ISO 4759-1:2000. The nominal diameter, standard thread pitch, internal thread minor diameter, and crest height values ​​corresponding to standard nuts are shown in Table 1, and the standard internal chamfer diameter corresponding to standard nuts is shown in Table 2.

[0048] Table 1. The nominal diameter, standard pitch, standard internal thread diameter, and standard thread height of 120 mm corresponding to different standard nuts, in mm.

[0049]

[0050] Table 2. The nominal diameter, standard pitch, standard internal thread diameter, and standard thread height of 120 mm corresponding to different standard nuts, in mm.

[0051]

[0052] It should be noted that the specifications of the extruded self-tapping nut of the present invention are M3, M4, M5, M6, M7, M8, M10, M12, M14, M16, M18, or M20. When the specification of the extruded self-tapping nut of the present invention is M3, the corresponding thread minor diameter values, taper height values, taper angles, pitches, and inner chamfer diameters of the standard threads 120, guide threads 130, first tapping threads 140, second tapping threads 150, and chip flutes 210 in the extruded self-tapping nut all correspond to those of the M3 standard nut, as shown in the first row of Tables 1 and 2.

[0053] For example, when the specification of the extruded self-drilling nut of the present invention is M3, the standard thread of the M3 standard nut is 120 mm high. 标准 is 0.270633mm, so the height H2 of the second self-tapping tooth 150 in the extruded self-tapping nut is 0.270633mm to 0.8 0.270633mm, the first self-tapping thread 140 has a height H2 of 0.8 0.270633mm to 0.6 0.270633mm, the tooth height H4 of the guide tooth 130 is 0.3 0.270633mm vs. 0.6 0.270633mm. The standard internal thread minor diameter value in the tolerance zone 6H of M3 in the standard nut is 2.459mm. Then the minor diameter value d1 of the standard tooth 120 and the minor diameter value d2 of the second self-tapping tooth 150 of the present invention are both 2.459mm, while the minor diameter value d3 of the first self-tapping tooth 140 is 2.459mm to D, and the minor diameter value d4 of the guide tooth 130 is 2.459mm to 1.2D. The pitch of the standard tooth 120, the pitch of the second self-tapping tooth 150, the pitch of the first self-tapping tooth 140 and the pitch of the guide tooth 130 are all equal to the standard pitch in the standard nut, which are all 0.5mm. The inner chamfer diameter d of the chip collecting groove 210 a 1.2 3mm<d a <1.2 3.45mm, other specifications are the same.

[0054] The extruded self-tapping nut preparation process forms an extruded thread on the extruded self-tapping nut 10 through extrusion plastic deformation, so that the extruded self-tapping nut 10 has the advantage of low material loss, and the metal fiber structure of the extruded thread is continuous and not cut, and the strength of the thread is improved, thereby effectively improving the tapping of the extruded self-tapping nut 10 on the external connecting piece. Moreover, the extruded thread of the present invention undergoes cold work hardening due to extrusion, thereby significantly improving the wear resistance of the thread surface. The extruded self-tapping nut 10 is in full contact with the surface of the external connecting piece, thereby reducing the possibility of vibration loosening.

[0055] Example 2: An extruded self-tapping nut 10, which is prepared by the extruded self-tapping nut preparation process of Example 1.

[0056] The extruded self-tapping nut 10 has the advantage of low material loss, and the metal fiber structure of the extruded thread is continuous and not cut, so the strength of the thread is improved, thereby effectively improving the tapping of the external connecting piece by the extruded self-tapping nut 10. In addition, the extruded thread of the present invention undergoes cold work hardening due to extrusion, thereby significantly improving the wear resistance of the thread surface. The extruded self-tapping nut 10 is in full contact with the surface of the external connecting piece, thereby reducing the possibility of vibration loosening.

[0057] Example 3: An application of an extruded self-tapping nut, wherein the extruded self-tapping nut 10 is prepared by the extruded self-tapping nut preparation process of Example 1 and a cylindrical pin is self-drilled to form a fastener.

[0058] Since the metal fiber structure of the thread of the extruded self-tapping nut 10 is continuous and not cut, the strength of the thread is improved, thereby effectively improving the tapping of the cylindrical pin by the extruded self-tapping nut 10. In addition, the extruded thread of the present invention undergoes cold work hardening due to extrusion, thereby significantly improving the wear resistance of the thread surface. The extruded self-tapping nut 10 is in full contact with the surface of the cylindrical pin, thereby reducing the possibility of vibration loosening.

[0059] Example 4: Application of an extruded self-tapping nut in an automobile grounding device. The extruded self-tapping nut preparation process of Example 1 is used to prepare an extruded self-tapping nut 10 for use as a nut in an automobile grounding device.

[0060] like Figure 4 As shown, the grounding device includes an extruded self-tapping nut 10 of the present invention, a connecting pin 20 with a smooth surface, and a grounding terminal 30. The connecting pin 20 is a structural diagram after being self-threaded by the extruded self-tapping nut 10.

[0061] It should be noted that in the current automobile manufacturing process, exposed parts of the vehicle body need to be electrophoretically painted to improve corrosion resistance, but welding cannot be performed after electrophoresis. Therefore, the current grounding device needs to be welded to the vehicle body and then electrophoretically coated together with the vehicle body. However, since the grounding device needs to be conductive, the paint surface produced by the vehicle surface treatment can hinder the flow of current, so it needs to be installed in multiple steps. Due to the limitations of these conditions, the current mainstream installation of the grounding device can only be completed after the bolts, nuts, and grounding terminal 30 are prepared separately in the early stage. The grounding device manufacturer needs to assemble the bolts and nuts before shipping the whole unit. Once the bolts and nuts arrive at the automobile manufacturer, the assembled bolts and nuts are installed on the vehicle frame and electrophoretically coated together. The bolts and nuts are then disassembled, the grounding terminal 30 is installed, and finally the nuts are re-installed on the bolts to complete the grounding device installation process. This mainstream installation process requires the bolts and nuts to be disassembled and installed at least twice, and the grounding device manufacturer needs to assemble the bolts and nuts in advance, which is not only cumbersome but also incurs a large amount of additional costs. More importantly, if the nut and bolt are not assembled tightly enough during the electrophoretic process, electrophoretic paint will penetrate between the thread and the supporting surface. Electrophoretic paint is insulating, so it will affect the conductive effect of the grounding device. At the same time, the presence of electrophoretic paint will affect the threaded connection between the bolt and the nut, thereby affecting the subsequent installation of the nut into the bolt.

[0062] The application of the extruded self-tapping nut of the present invention in the automobile grounding device is that the extruded self-tapping nut 10 is directly rotated and screwed onto the outer surface of the connecting pin 20, so that the connecting pin 20 extrude a thread matching the extruded self-tapping nut 10, and at the same time, the electrophoretic paint attached to the surface of the connecting pin 20 is scraped off to form an electrical connection contact surface between the extruded self-tapping nut 10 and the connecting pin 20; the grounding terminal 30 is sleeved on the outer periphery of the connecting pin 20, and the connecting pin 20 is fixedly connected to the external fixing surface 40, and the extruded self-tapping nut 10 is threadedly connected to the connecting pin 20, so that the connecting pin 20, the extruded self-tapping nut 10 and the external fixing surface 40 form a fixing part of the grounding terminal 30, so that the grounding terminal 30 is fixed and constitutes an electrical conduction channel.

[0063] Since the grounding device can form an electrical conduction channel as long as there is no electrophoretic coating anywhere among the extruded self-tapping nut 10, the grounding terminal 30, and the connecting pin 20 and they are connected, the current flows through the grounding terminal 30, the flange surface of the extruded self-tapping nut 10, the body of the extruded self-tapping nut 10, the thread of the extruded self-tapping nut 10, the thread of the connecting pin 20, the body of the connecting pin 20, and then to the external fixing surface 40.

[0064] It should be noted that the extruded self-tapping nut 10 of the present invention can perform self-tapping threads on the connecting pin 20. Specifically, the internal thread of the extruded self-tapping nut 10 is used to extrude and deform the surface of the connecting pin 20, so that the surface of the connecting pin 20 forms a thread that matches the thread of the extruded self-tapping nut 10. This process causes the surface of the connecting pin 20 to deform to produce threads. Unlike the cutting and tapping to produce threads in the prior art, the connecting pin 20 will not have material loss, thereby improving the material utilization rate of the connecting pin 20. Moreover, the connecting pin 20 does not need to be threaded in advance, eliminating the manufacturing cost of the bolt thread.

[0065] Furthermore, when the extruded self-drilling nut 10 of the present invention is applied to an automobile grounding device, even when the extruded self-drilling nut 10 is used to self-drill the connecting pin 20 after electrophoresis, the surface of the connecting pin 20 will deform, and impurities attached to the surface of the connecting pin 20 will fall off due to electrophoretic paint. Therefore, an effective electrical connection contact surface is still formed between the extruded self-drilling nut 10 and the connecting pin 20. Since the extruded self-drilling nut 10 can both self-drill the connecting pin 20 and scrape off impurities attached to the surface of the connecting pin 20, it is not necessary to follow the installation steps of the prior art. The assembly sequence of the extruded self-drilling nut 10 can be selected according to actual needs, greatly improving the installation flexibility of the grounding device.

[0066] The connecting pin 20 of the automobile grounding device used in the present invention can be a raised polished rod portion integrally formed with the external fixing surface 40. The connecting pin 20 of the automobile grounding device used in the present invention can also be a welding pin independent of the external fixing surface 40, and the end face of the welding pin is provided with a welding cone surface, which is fixedly connected to the external fixing surface 40 by welding.

[0067] Therefore, the connecting pin 20 can be composed of a polished rod pin. When the connecting pin 20 is an independent welding pin, the welding pin can be formed by cold heading. When the connecting pin 20 connected by the present invention is a raised polished rod portion integrally formed with the external fixing surface 40, the connecting pin 20 of the present invention is a part of the external fixing surface 40 and can be formed by die casting. The specific structure of the connecting pin 20 can be determined according to actual conditions. The connecting pin 20 is only a protruding polished rod, and no additional thread processing operation is required. Therefore, the connecting pin 20 of the present invention can be a raised polished rod portion integrally formed with the external fixing surface 40, or a welding pin that is independent of the external fixing surface 40, and the end face of the welding pin is provided with a welding cone surface, and the welding cone surface is fixedly connected to the external fixing surface 40 by welding. When the connecting pin 20 is a raised polished rod portion integrally formed with the external fixing surface 40, there is no need to add additional production of the connecting pin 20, nor is there an additional fixing step between the connecting pin 20 and the external fixing surface 40, which greatly shortens the production time. In addition, the integrally formed connecting pin 20 can also improve the connection strength with the external fixing surface 40. Furthermore, the integrally formed connecting pin 20 of the present invention completely changes the manufacturing concept of the prior art grounding device.

[0068] The beneficial effects of the application of the extruded self-tapping nut in the automobile grounding device are as follows: 1. Since the metal fiber structure of the thread of the extruded self-tapping nut 10 is continuous and not cut, the strength of the thread is improved, thereby effectively improving the tapping of the connecting pin 20 by the extruded self-tapping nut 10. In addition, the extruded thread of the present invention undergoes cold work hardening due to extrusion, thereby significantly improving the wear resistance of the thread surface. The extruded self-tapping nut 10 is in full contact with the surface of the connecting pin 20, thereby reducing the possibility of vibration loosening. 2. The use of the extruded self-tapping nut 10 to extrude threads on the connecting pin 20 saves the manufacturing cost of the bolt thread and improves the utilization rate of the material of the connecting pin 20; 3. The extruded self-tapping nut 10 can also scrape off impurities attached to the surface of the connecting pin 20, such as electrophoretic paint 50, to ensure that an effective electrical connection contact surface is formed between the extruded self-tapping nut 10 and the connecting pin 20; 4. The installation process of the grounding device of the present invention is diversified. The present invention does not need to combine the extruded self-tapping nut 10 with the connecting pin 20 and then perform electrophoresis as in the prior art, thus getting rid of the limitation of the order of electrophoresis. 5. Since the connecting pin 20 of the present invention does not need to be pre-processed with threads, the connecting pin 20 can be directly integrally formed on the external fixing surface 40. There is no need to increase the production of the connecting pin 20 or the additional fixing steps of the connecting pin 20 and the external fixing surface 40, which greatly shortens the production time. In addition, the integrally formed connecting pin 20 can also improve the connection strength with the external fixing surface 40.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A process for preparing an extruded self-drilling nut, characterized in that: In the thread processing process, the nut through hole is extruded and plastically deformed by an extrusion tool with a thread tooth profile, so that the through hole wall is extruded into a thread with a metal fiber structure as a continuous fiber structure, thereby obtaining an internal threaded hole.

2. The process for preparing an extruded self-drilling nut according to claim 1, wherein: The extrusion type self-tapping nut is provided with a flange and a main body, and the flange is integrally connected to the lower bottom surface of the main body; The main body is provided with a circular through hole.

3. The process for preparing an extruded self-drilling nut according to claim 2, wherein: In the thread processing step, the extrusion tool is rotated and screwed into the interior of the circular through hole from one side of the flange, and the inner wall surface of the circular through hole is extruded to form the internal threaded hole.

4. The process for preparing an extruded self-drilling nut according to claim 2, wherein: During the forging process, a chip collecting groove is formed on the surface of the flange, which is concave in the direction of the main body, and the chip collecting groove is connected to the through hole; The chip collecting groove is used to accommodate the chips generated when the external connecting piece is self-drilled.

5. The process for preparing an extruded self-drilling nut according to claim 4, wherein: The threads in the internal threaded hole are divided into standard teeth, guide teeth, first self-tapping teeth and second self-tapping teeth. The standard teeth, the second self-tapping teeth, the first self-tapping teeth and the guide teeth are arranged in sequence from top to bottom, and the chip collecting groove is located at the lower part of the guide teeth.

6. The process for preparing an extruded self-drilling nut according to claim 5, characterized in that: The crest height of the standard thread is defined as H1, the crest height of the second self-tapping thread is defined as H2, the crest height of the first self-tapping thread is defined as H3, and the crest height of the guide thread is defined as H4. H1>H2>H3>H4 exists.

7. The process for preparing an extruded self-drilling nut according to claim 5, wherein: The minor diameter value of the standard thread is equal to the minor diameter value of the second self-tapping thread; The minor diameter value of the first self-tapping thread and the minor diameter value of the guide thread are both smaller than the minor diameter value of the standard thread.

8. An extrusion-type self-tapping nut, characterized in that: The nut is prepared by the extrusion type self-tapping nut preparation process as described in any one of claims 1 to 7.

9. An application of an extrusion type self-tapping nut, characterized in that: The extruded self-tapping nut obtained by the extruded self-tapping nut preparation process according to any one of claims 1 to 7 is used to self-tap a cylindrical pin to form a fastener.

10. Application of an extruded self-tapping nut in an automobile grounding device, characterized in that: The extruded self-tapping nut prepared by the extruded self-tapping nut preparation process according to any one of claims 1 to 7 is used as a nut in an automobile grounding device.

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