A self-tapping external thread assist device for light alloy fasteners
Patent Information
- Application Number
- CN202522389529.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-11
- Publication Date
- 2026-10-20
- Estimated Expiration
- 2035-11-11
AI Technical Summary
[0003]现有技术中，采用的自攻紧固件为钢材质，钢制的自攻紧固件在攻入轻合金时，易导致工件螺纹滑牙，轻合金与钢的电位差易引发电化学腐蚀，钢与轻合金的热膨胀系数差异，会导致预紧力衰减；钢制的自攻紧固件在冷态攻入时，轻合金延展性差，攻入较困难且易产生金属碎屑，残余应力导致疲劳强度下降，螺纹啮合率低，影响螺纹的使用性能
[0015]与现有技术相比，本实用新型的有益效果在于：设计一种适用于轻合金紧固件进行自攻外螺纹的辅助装置，包括主体和加热件，所述加热件设于所述主体的外壁，且所述加热件能够沿所述主体的外壁进行垂直移动，下降加热件，加热件对需要形成外螺纹的光杆销进行加热，提升了轻合金的延展性，加热结束后，上升加热件，主体与光杆销位置对齐，自攻螺母从主体经过并落于加热后的光杆销，拧紧件从主体进入并接触拧动自攻螺母，在光杆销外壁形成高强度的啮合螺纹，不容易发生塑性变形、也不会出现螺纹滑牙的现象、不容易断裂、自锁性强、在振动或动态载荷下不容易松动，也不会产生细小和易燃的切屑，防止燃烧或爆炸情况发生。
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Figure CN224866494U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of self-tapping thread auxiliary devices, and in particular to a self-tapping external thread auxiliary device for light alloy fasteners. Background Technology
[0002] With the development of lightweighting trend, light alloys (magnesium / aluminum alloys) are widely used in new energy vehicles, aerospace and other fields. Taking new energy vehicles as an example, the doors, hoods, fenders, anti-collision beams, body frames, control arms, steering knuckles, suspension components and so on of new energy vehicles are all made of light alloys. Light alloy door and other components are often connected to the body frame by self-tapping screws or self-tapping bolts. The instrument panel, A, B, C pillar interior, center console and other parts are also fixed to the body by self-tapping screws.
[0003] In the existing technology, the self-tapping fasteners used are made of steel. When steel self-tapping fasteners are used to tap into light alloys, the workpiece threads are prone to stripping. The potential difference between light alloys and steel can easily cause electrochemical corrosion. The difference in the coefficients of thermal expansion between steel and light alloys can lead to a decrease in preload. When steel self-tapping fasteners are used in a cold state, the poor ductility of light alloys makes it difficult to tap into them and easily produces metal chips. Residual stress leads to a decrease in fatigue strength, low thread engagement rate, and affects the performance of the threads.
[0004] Therefore, light alloy self-tapping fasteners are now used instead of steel self-tapping fasteners. However, during the self-tapping connection between light alloy fasteners and light alloy workpieces, when the light alloy fasteners are cutting or pressing the light alloy workpiece, due to the lower hardness of the light alloy compared to steel, both the workpiece and the fasteners are prone to plastic deformation, thread stripping, or even breakage due to local stress concentration. Even if the threads are successfully tapped, the thread engagement rate between the fastener and the workpiece is low, and the self-locking performance is poor, making it easy to loosen under vibration or dynamic loads. Light alloys have poor ductility and machinability in the cold state, and cannot form high-strength engagement threads through local deformation during the self-tapping process. If the light alloy used is a magnesium alloy, magnesium alloys are more likely to produce fine, flammable chips during cutting, posing a risk of combustion or explosion in confined spaces (such as battery packs and motor compartments). Magnesium alloys are also more sensitive to humid environments and salt spray, and have poorer corrosion resistance. Utility Model Content
[0005] This invention provides a self-tapping external thread auxiliary device for light alloy fasteners to solve at least one of the problems mentioned in the background art.
[0006] The technical solution of this utility model is as follows: This utility model discloses an auxiliary device for self-tapping external threads on light alloy fasteners, used to generate external threads on smooth pins. The light alloy fastener uses a self-tapping nut, comprising a main body and a heating element. The heating element is located on the outer wall of the main body and can move vertically along the outer wall of the main body. First, the heating element descends to heat the smooth pin. After heating, the heating element rises, aligning the main body with the smooth pin. The main body acts as a track for the self-tapping nut to accurately fall onto the smooth pin. The tightening element enters from the main body and contacts the self-tapping nut, causing the self-tapping nut to rotate, thus forming external threads on the smooth pin. Preheating increases the elongation of the light alloy, preventing cracking of the thin-walled shell during the self-tapping assembly process, thus solving the cracking problem. Preheating before tapping reduces the tapping torque, increases the thread engagement rate, achieves efficient and reliable assembly, and reduces assembly difficulty.
[0007] The heating element is either a coil heating element or a plasma heating element.
[0008] Specifically, the coil heating element includes a support shell, a first temperature measuring element, and a heating coil. The inner wall of the support shell is provided with a first mounting groove and an inner extension edge. The first temperature measuring element is disposed in the first mounting groove, and the heating coil is located on the inner extension edge.
[0009] Specifically, the plasma heating element includes a housing, a second temperature measuring element, an air inlet channel, and a nozzle. The inner wall of the housing is provided with a second mounting groove, and the second temperature measuring element is disposed in the second mounting groove. The air inlet channel is disposed inside the housing, and the nozzle is disposed inside the housing. The air inlet channel and the nozzle are interconnected.
[0010] Furthermore, the main body includes an inlet end and an outlet end, and the outlet end is provided with a retractable clamp.
[0011] Furthermore, it also includes a tightening component and a self-tapping nut. The self-tapping nut and the tightening component enter the main body from the inlet end. The tightening component can extend and retract to contact the self-tapping nut and drive the self-tapping nut to rotate. The self-tapping nut can be inserted first and then the tightening component is inserted into the main body, or the self-tapping nut can be installed in the tightening component first and then both are inserted into the main body. This allows the tightening component to extend and retract to contact the self-tapping nut and drive the self-tapping nut to rotate, so that the smooth pin forms an internal thread and tightly engages with the self-tapping nut.
[0012] It is worth noting that the auxiliary device can be either a heating device or a device that has both heating and self-tapping internal threads.
[0013] The first option is that there is only one inlet, and the self-tapping nut and the tightening component both enter the main body from the same port.
[0014] The second option is as follows: There are two inlet ends, namely a first inlet end and a second inlet end. The tightening member enters the main body from the first inlet end, and the self-tapping screw enters the main body from the second inlet end.
[0015] Compared with the prior art, the beneficial effects of this utility model are as follows: An auxiliary device suitable for self-tapping external threads on light alloy fasteners is designed, including a main body and a heating element. The heating element is located on the outer wall of the main body and can move vertically along the outer wall of the main body. The heating element descends to heat the smooth pin that needs to form an external thread, improving the ductility of the light alloy. After heating, the heating element rises, aligning the main body with the smooth pin. The self-tapping nut passes through the main body and falls onto the heated smooth pin. The tightening element enters from the main body and contacts the self-tapping nut, forming a high-strength meshing thread on the outer wall of the smooth pin. This prevents plastic deformation, thread stripping, breakage, and strong self-locking properties. It is also less prone to loosening under vibration or dynamic loads and does not produce fine and flammable chips, preventing combustion or explosion. Attached Figure Description
[0016] Figure 1 A schematic diagram of the overall structure of a coil heating element used in a self-tapping external thread auxiliary device for a light alloy fastener; Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure; Figure 3 This is a schematic diagram of the cross-sectional structure of the coil heating element; Figure 4 This is an exploded structural diagram of the coil heating element; Figure 5 This is a schematic diagram of the cross-sectional structure of the plasma heating element; Figure 6 This is a schematic diagram of the exploded structure of a plasma heating element; Figure 7 for Figure 1 A cross-sectional structural diagram of a coil heater positioned around a polished rod pin; Figure 8 A schematic diagram of the overall structure of a self-tapping external thread auxiliary device for a light alloy fastener using a plasma heater; Figure 9 for Figure 8 A schematic diagram of the cross-sectional structure; Reference numerals: 1. Main body; 11. Inlet end; 111. First tightening component; 112. Second tightening component; 12. Outlet end; 13. Adjustable clamp; 2. Heating component; 3. Coil heating component; 31. Support shell; 311. First mounting groove; 312. Inner extension edge; 32. First temperature measuring component; 33. Heating coil; 4. Plasma heater; 41. Shell; 411. Second mounting groove; 42. Second temperature measuring component; 43. Air inlet channel; 44. Nozzle; 5. Tightening component; 6. Self-tapping nut; 7. Smooth rod pin. Detailed Implementation
[0017] Example 1
[0018] Please refer to Figures 1-7 This utility model provides an auxiliary device for self-tapping external threads of light alloy fasteners, used to generate external threads on the smooth pin 7. The light alloy fastener is a light alloy self-tapping nut 6, and a tightening element 5 applies force to the self-tapping nut 6. The tightening element 5 can be a single bit or a bit on an automatic tightening gun; it can be manual, which is used for manual operation and is suitable for small-batch production; or it can be electric, which is used in conjunction with an automatic tightening gun. It includes a main body 1 and a heating element 2. The heating element 2 is disposed on the outer wall of the main body 1. Specifically, the heating element 2 can be detachably disposed on the outer wall of the main body 1 and can move vertically along the outer wall of the main body 1. When designed as a manual type, the heating element 2 is moved vertically by human hands. When designed as an electric type, a slide rail and a motor can be provided on the automatic tightening gun to realize the electric drive of the heating element 2 to move vertically.
[0019] The operating steps are as follows: First, lower the heating element 2 to heat the smooth pin 7. After heating, raise the heating element 2 and align the main body 1 with the smooth pin 7. The main body 1 serves as a track for the self-tapping nut 6 to fall accurately onto the smooth pin 7. The tightening element 5 enters from the main body 1 and contacts the self-tapping nut 6, causing the self-tapping nut 6 to rotate, thus forming an external thread on the smooth pin 7. Alternatively, the self-tapping nut 6 can be installed on the tightening element 5 first, and the self-tapping nut 6 and the tightening element 5 can be inserted into the main body 1 together. The tightening element 5 causes the self-tapping nut 6 to rotate, thus forming an external thread on the smooth pin 7.
[0020] By preheating to increase the elongation of the light alloy, cracking of the thin-walled shell during self-tapping assembly can be avoided, thus solving the cracking problem. Preheating before tapping can reduce the tapping torque, increase the thread engagement rate, achieve efficient and reliable assembly, and reduce the assembly difficulty. Furthermore, a high-strength engagement thread is formed on the inner wall of the polished pin 7, which is not prone to plastic deformation, will not cause thread stripping, is not prone to breakage, has strong self-locking properties, is not prone to loosening under vibration or dynamic loads, and will not produce fine and flammable chips, thus preventing combustion or explosion.
[0021] Specifically, the heating element 2 is a coil heating element 3. When designed as a manual type, the coil heating element 3 can be heated by connecting an electrical wire or by being powered by a lithium battery. When designed as an electric type, the coil heating element 3 is directly connected to the power supply of the automatic tightening gun for conduction. The coil heating element 3 includes a support shell 31, a first temperature measuring element 32, and a heating coil 33. The inner wall of the support shell 31 is provided with a first mounting groove 311 and an inner extension edge 312. The first temperature measuring element 32 is located in the first mounting groove 311, and the heating coil 33 is located on the inner extension edge 312. The first temperature measuring element 32 monitors the heating temperature of the heating coil 33. The control module controls the energization or de-energization of the heating coil 33 according to the preset temperature value / temperature range and the temperature feedback from the first temperature measuring element 32.
[0022] The main body 1 includes two inlet ends 11 and an outlet end 12. The main body 11 is Y-shaped, with the two inlet ends 11 being the first inlet end 111 and the second inlet end 112. The tightening member 5 enters the main body 1 from the first inlet end 111, and the self-tapping screw enters the main body 1 from the second inlet end 112. When designed as an electric type, the second inlet end 112 can also be a swing arm type. The second inlet end 112 is only opened when the self-tapping nut 6 is needed, and closed when the self-tapping nut 6 is not needed. The outlet end 12 is provided with a retractable clamp 13. Therefore, when the self-tapping nut 6 is in the retractable clamp 13, the retractable clamp 13 can hold the self-tapping screw and buffer the speed at which the self-tapping nut 6 enters the guide pin 7. When the tightening member 5 applies force to the self-tapping nut 6, the diameter of the retractable clamp 13 increases, and the self-tapping nut 6 exits from the outlet end 12.
[0023] Example 2
[0024] Please refer to Figure 8 and Figure 9 This utility model provides an auxiliary device for self-tapping external threads of light alloy fasteners, used to generate external threads on the smooth pin 7. The light alloy fastener is a light alloy self-tapping nut 6, and a tightening element 5 applies force to the self-tapping nut 6. The tightening element 5 can be a single bit or a bit on an automatic tightening gun; it can be manual, which is used for manual operation and is suitable for small-batch production; or it can be electric, which is used in conjunction with an automatic tightening gun. It includes a main body 1 and a heating element 2. The heating element 2 is disposed on the outer wall of the main body 1 and can move vertically along the outer wall of the main body 1. When designed as a manual type, the heating element 2 is moved vertically by human hands. When designed as an electric type, a slide rail and a motor can be installed on the automatic tightening gun to realize the electric drive of the heating element 2 to move vertically.
[0025] The operating steps are as follows: First, lower the heating element 2 to heat the smooth pin 7. After heating, raise the heating element 2 and align the main body 1 with the smooth pin 7. The main body 1 serves as a track for the self-tapping nut 6 to fall accurately onto the smooth pin 7. The tightening element 5 enters from the main body 1 and contacts the self-tapping nut 6, causing the self-tapping nut 6 to rotate, thus forming an external thread on the smooth pin 7. Alternatively, the self-tapping nut 6 can be installed on the tightening element 5 first, and the self-tapping nut 6 and the tightening element 5 can be inserted into the main body 1 together. The tightening element 5 causes the self-tapping nut 6 to rotate, thus forming an external thread on the smooth pin 7.
[0026] By preheating to increase the elongation of the light alloy, cracking of the thin-walled shell during self-tapping assembly can be avoided, thus solving the cracking problem. Preheating before tapping can reduce the tapping torque, increase the thread engagement rate, achieve efficient and reliable assembly, and reduce the assembly difficulty. Furthermore, a high-strength engagement thread is formed on the inner wall of the polished pin 7, which is not prone to plastic deformation, will not cause thread stripping, is not prone to breakage, has strong self-locking properties, is not prone to loosening under vibration or dynamic loads, and will not produce fine and flammable chips, thus preventing combustion or explosion.
[0027] Specifically, the heating element 2 is a plasma heating element 4. When designed as a manual type, the plasma heating element 4 can only achieve coil heating by connecting an electrical wire. When designed as an electric type, the plasma heating element 4 is directly connected to the power supply on the automatic tightening gun for electrical conduction. The plasma heating element 4 includes a housing 41, a second temperature measuring element 42, an air intake channel 43, and a nozzle 44. The inner wall of the housing 41 is provided with a second mounting groove 411, and the second temperature measuring element 42 is located in the second mounting groove 411. The air intake channel 43 is located inside the housing 41, and the nozzle 44 is located inside the housing 41. The air intake channel 43 and the nozzle 44 are interconnected. The second temperature measuring element 42 detects the heating temperature of the nozzle 44 during operation. The control module controls the air intake channel 43 to be closed or opened based on the preset temperature value / temperature range and the temperature feedback from the second temperature measuring element 42.
[0028] The main body 1 includes two inlet ends 11 and one outlet end 12. The main body 11 is Y-shaped. The two inlet ends 11 are the first inlet end 111 and the second inlet end 112, respectively. The tightening member 5 enters the main body 1 from the first inlet end 111, and the self-tapping screw enters the main body 1 from the second inlet end 112. When designed as an electric type, the second inlet end 112 can also be a swing arm type. The second inlet end 112 is only opened when the self-tapping nut 6 is needed, and closed when the self-tapping nut 6 is not needed. The outlet end 12 is provided with a retractable clamp 13. Therefore, when the self-tapping nut 6 is in the retractable clamp 13, the retractable clamp 13 can hold the self-tapping screw and buffer the speed at which the self-tapping nut 6 enters the guide pin 7. When the tightening member 5 applies force to the self-tapping nut 6, the diameter of the retractable clamp 13 increases, and then the self-tapping nut 6 exits from the outlet end 12.
[0029] It is worth noting that in Embodiments 1 and 2, the main body 1 can also be designed to include an inlet end 11 and an outlet end 12, the main body 1 is cylindrical, and the self-tapping nut 6 and the tightening member 5 both enter the main body 1 from the same inlet end 11.
[0030] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.
Claims
1. A self-tapping external thread auxiliary device for light alloy fasteners, characterized in that, It includes a main body (1) and a heating element (2), the heating element (2) is disposed on the outer wall of the main body (1), and the heating element (2) can move vertically along the outer wall of the main body (1).
2. The self-tapping external thread auxiliary device for light alloy fasteners according to claim 1, characterized in that, The heating element (2) is either a coil heating element (3) or a plasma heating element (4).
3. The self-tapping external thread auxiliary device for light alloy fasteners according to claim 2, characterized in that, The coil heating element (3) includes a support shell (31), a first temperature measuring element (32) and a heating coil (33). The inner wall of the support shell (31) is provided with a first mounting groove (311) and an inner extension edge (312). The first temperature measuring element (32) is located in the first mounting groove (311), and the heating coil (33) is located on the inner extension edge (312).
4. The self-tapping external thread auxiliary device for light alloy fasteners according to claim 2, characterized in that, The plasma heating element (4) includes a housing (41), a second temperature measuring element (42), an air inlet channel (43), and a nozzle (44). The inner wall of the housing (41) is provided with a second mounting groove (411). The second temperature measuring element (42) is located in the second mounting groove (411). The air inlet channel (43) is located inside the housing (41). The nozzle (44) is located inside the housing (41). The air inlet channel (43) and the nozzle (44) are interconnected.
5. The self-tapping external thread auxiliary device for light alloy fasteners according to claim 1, characterized in that, The main body (1) includes an inlet end (11) and an outlet end (12), and the outlet end (12) is provided with a retractable clamp (13).
6. The self-tapping external thread auxiliary device for light alloy fasteners according to claim 5, characterized in that, It also includes a tightening member (5) and a self-tapping nut (6), the self-tapping nut (6) and the tightening member (5) enter the body (1) from the inlet end (11), the tightening member (5) can extend and retract to contact the self-tapping nut (6) and drive the self-tapping nut (6) to rotate.
7. The self-tapping external thread auxiliary device for light alloy fasteners according to claim 6, characterized in that, The inlet end (11) includes a first inlet end (111) and a second inlet end (112). The tightening member (5) enters the body (1) from the first inlet end (111), and the self-tapping nut (6) enters the body (1) from the second inlet end (112).