Locking piece
By designing interlaced gear sections and blank sections in the locking fastener, the problems of large shrinkage rate and stress concentration of plastic parts in traditional locking fasteners are solved, thereby achieving stress dispersion and improved torsional resistance, and eliminating abnormal noise.
Patent Information
- Application Number
- CN202610060466.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-16
- Publication Date
- 2026-02-27
AI Technical Summary
Traditional fasteners have a large shrinkage rate in plastic parts, which leads to stress concentration near the neck below the dome of the plastic part, and the movement of the plastic part relative to the metal part produces abnormal noise.
Design a locking device comprising a plastic column and a metal column. The top of the plastic column has staggered first gear sections that engage with the inner boss convex arc surface of the metal column, thereby dispersing the contact surface, reducing the shrinkage rate, and optimizing stress distribution through the staggered gear sections and blank sections.
It effectively reduced the shrinkage rate of plastic columns, reduced stress concentration, improved tensile and torsional resistance, and eliminated noise problems.
Smart Images
Figure CN121576339A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to a manufacturing technique for a composite component made of dissimilar materials, and more particularly to a locking device. Background Technology
[0002] The locking posts on existing die-cast parts are designed with a plastic coating, combining metal and plastic components. Traditional locking posts employ a dome design. This dome design results in a larger continuous contact area between the metal and plastic components. Consequently, the plastic component experiences greater shrinkage forces, causing the neck below the dome to be pulled down, leading to severe stress concentration near the neck of the dome.
[0003] Furthermore, after the locking post is formed, the significant shrinkage of the plastic part creates a large gap between it and the metal part. When the product containing the locking post shakes, the plastic part moves up and down relative to the metal part, colliding with it and producing noise. Summary of the Invention
[0004] Therefore, one objective of this disclosure is to provide a locking device that can solve the problems of large shrinkage rate of plastic parts, severe stress concentration near the neck below the dome of the plastic parts, and abnormal noise caused by the plastic parts moving relative to the metal parts and colliding with the metal parts.
[0005] In accordance with the aforementioned objectives of this disclosure, a locking device is proposed. This locking device comprises a plastic post and a metal post. The plastic post comprises a post body and a post top. The post body has a first locking hole extending along the length of the post body. The post top is disposed on the post body and has a second locking hole aligned with the first locking hole. The post top includes a top portion and a first gear portion engaged with the lower surface of the top portion. The first gear portion includes a plurality of first teeth and a plurality of first tooth grooves, which are arranged in an alternating ring. The metal post covers the outer surface of the plastic post and is embedded in the first tooth grooves.
[0006] According to one embodiment of this disclosure, the outer surface of the first gear portion includes a concave arc surface that extends to the lower surface of the top. The metal pillar includes an inner boss, and the inner edge of the inner boss includes a convex arc surface that engages with the concave arc surface.
[0007] According to one embodiment of this disclosure, the aforementioned metal column includes a top wall located on and surrounding the inner boss.
[0008] According to one embodiment of this disclosure, the top is located on the inner boss, and the height of the top is lower than the height of the top wall.
[0009] According to one embodiment of the present disclosure, the aforementioned column includes a second gear portion. The second gear portion includes a plurality of second teeth and a plurality of second tooth slots, which are arranged in an alternating ring shape.
[0010] According to one embodiment of this disclosure, the aforementioned column further includes a blank portion and a base plate. The blank portion is located between the first gear portion and the second gear portion, wherein the blank portion has a smooth outer surface. The base plate is disposed below the second gear portion.
[0011] According to one embodiment of the present disclosure, the first tooth and the second tooth are arranged alternately.
[0012] According to one embodiment of this disclosure, the density of the first tooth is twice the density of the second tooth.
[0013] According to one embodiment of the present disclosure, the length of the first tooth is less than the length of the second tooth.
[0014] According to one embodiment of the present disclosure, the first tooth and the second tooth are trapezoidal structures.
[0015] According to one embodiment of the present disclosure, each second tooth includes an upper convex arc edge.
[0016] According to the above embodiment, the first gear portion at the top of the plastic column of the fastener can disperse the contact portion between the plastic column and the metal column into several contact surfaces, thus achieving a stress dispersion effect and reducing the shrinkage rate of the plastic column. Furthermore, the outer surface of the first gear portion includes a concave arc surface extending to the lower surface of the top, and the inner edge of the inner boss of the metal column includes a convex arc surface that can engage with this concave arc surface. The engagement between the top of the column and the convex arc surface of the inner boss of the metal column through the concave arc surface of the first gear portion effectively reduces the stress at the joint between the top and the first gear portion. Moreover, the first tooth of the first gear portion can be firmly anchored in the portion of the metal column covering it, thus significantly enhancing the tensile and torsional resistance of the plastic column. Attached Figure Description
[0017] A better understanding of the features disclosed herein can be obtained from the following detailed description taken in conjunction with the accompanying drawings. It should be noted that, according to industry standard practice, the features are not drawn to scale. In fact, the dimensions of the features can be arbitrarily increased or decreased for clarity of discussion.
[0018] Figure 1 A perspective view of a device including a locking fastener according to one embodiment of the present disclosure is shown.
[0019] Figure 2 A perspective view of a plastic post of a locking device according to one embodiment of the present disclosure is shown.
[0020] Figure 3 A cross-sectional schematic diagram of a locking device according to one embodiment of the present disclosure is shown.
[0021] Figure 4A cross-sectional schematic diagram of a metal post of a locking device according to one embodiment of the present disclosure is shown.
[0022] In the attached figures, the following labels are used:
[0023] 10: Locking hardware
[0024] 100: Plastic column
[0025] 110: Pillar
[0026] 112: First locking hole
[0027] 114: Second Gear Section
[0028] 114a: Second tooth
[0029] 114a': Upper convex arc edge
[0030] 114b: Second tooth groove
[0031] 116: Blank section
[0032] 116a: Outer surface
[0033] 118: Base Plate
[0034] 118a: Outer surface
[0035] 118b: Bottom surface
[0036] 120: Column top
[0037] 122: Second locking hole
[0038] 124: Top
[0039] 124a: Lower surface
[0040] 126: First Gear Section
[0041] 126a: First tooth
[0042] 126b: First tooth groove
[0043] 126c: Outer surface
[0044] 126c': Concave arc surface
[0045] 200: Metal Column
[0046] 210: First protruding structure
[0047] 220: First Groove
[0048] 230: Second protruding structure
[0049] 240: Second groove
[0050] 250: Inner boss
[0051] 252:convex arc surface
[0052] 260: Ceiling and Wall
[0053] DV: Device
[0054] LD: Length direction Detailed Implementation
[0055] The embodiments of this disclosure are discussed in detail below. However, it will be understood that the embodiments provide many applicable concepts that can be implemented in a wide variety of specific situations. The embodiments discussed and disclosed are for illustrative purposes only and are not intended to limit the scope of this disclosure. All embodiments of this disclosure reveal a variety of different features, but these features can be implemented individually or in combination as needed.
[0056] In addition, the terms "first," "second," etc. used in this article do not specifically refer to order or sequence, but are only used to distinguish elements or operations described using the same technical terms.
[0057] The spatial relationship between the two elements described in this disclosure applies not only to the orientations shown in the diagrams, but also to orientations not shown in the diagrams, such as inverted orientations. Furthermore, the terms "connection," "electrical connection," or similar expressions used in this disclosure to refer to two components are not limited to direct or electrical connections, but may also include indirect or electrical connections as needed.
[0058] The terms “approximately” and “substantially” as used herein generally refer to within 20%, 10%, or 5% of a given value or range. These values are merely examples and are not intended to be limiting. The terms “approximately” and “substantially” may refer to percentages of values as interpreted by one skilled in the art in accordance with the teachings herein.
[0059] Please refer to Figures 1 to 4 The diagrams illustrate, respectively, a perspective view of a device DV including a locking element 10 according to one embodiment of the present disclosure, a perspective view of the plastic post 100 of the locking element 10, a cross-sectional view of the locking element 10, and a cross-sectional view of the metal post 200 of the locking element 10. The locking element 10 can be applied to any device DV that needs to be assembled or combined with other devices by locking. For example, the locking element 10 can be a locking post for the back panel of a display device, or a locking post on a vehicle body or for various devices within the vehicle's cabin. The locking element 10 can be, for example, a screw post.
[0060] The locking device 10 mainly includes plastic posts 100 and metal posts 200. For example... Figure 2As shown, the plastic column 100 may include a column body 110 and a column top 120. The column body 110 may be, for example, a cylindrical structure. The column body 110 may also be any other suitable column structure, such as a polygonal column structure, which is not limited to this disclosure. Figure 3 As shown, the column body 110 has a first locking hole 112 disposed therein. The first locking hole 112 may extend, for example, along the length direction LD of the column body 110. That is, the central axis of the first locking hole 112 may be parallel to the length direction LD of the column body 110. The first locking hole 112 may not penetrate the column body 110. The first locking hole 112 may be, for example, a threaded hole with a threaded structure.
[0061] like Figure 2 As shown, the column top 120 is located on the column body 110 and is joined to the column body 110. The column top 120 and the column body 110 are combined as a single molded structure. Figure 3 As shown, the column top 120 has a second locking hole 122. The second locking hole 122 penetrates the column top 120 and is aligned with the first locking hole 112 of the column body 110. For example, the second locking hole 122 may extend through the column top 120 along the length direction LD of the column body 110. Furthermore, the central axis of the second locking hole 122 may, for example, overlap with the central axis of the first locking hole 112. In conjunction with the first locking hole 112, the second locking hole 122 may also be a threaded hole with a threaded structure.
[0062] like Figure 2 and Figure 3 As shown, the column top 120 may include a top 124 and a first gear portion 126. A second locking hole 122 penetrates both the top 124 and the first gear portion 126, thus both the top 124 and the first gear portion 126 are annular structures. The top 124 may be, for example, a circular ring structure, and the first gear portion 126 may be a quasi-circular ring structure. In some embodiments, the radial dimension of the top 124 is larger than the maximum radial dimension of the first gear portion 126. Therefore, the top 124 can completely cover the first gear portion 126.
[0063] A first gear portion 126 is disposed below the top 124 and engages with the lower surface 124a of the top 124. The first gear portion 126 includes a plurality of first teeth 126a and a plurality of first tooth grooves 126b. The first teeth 126a are protruding relative to the first tooth grooves 126b. These first teeth 126a and first tooth grooves 126b are arranged in a ring and interlaced with each other. That is, there is a recessed first tooth groove 126b between two adjacent first teeth 126a. In some embodiments, the outer surface 126c of the first gear portion 126 includes a concave arc surface 126c'. This concave arc surface 126c' is located on the upper part of the outer surface 126c and extends to the lower surface 124a of the top 124, and connects with the lower surface 124a.
[0064] like Figure 2 As shown, in some embodiments, the column 110 includes a second gear portion 114. The second gear portion 114 may be opposite to and spaced apart from the first gear portion 126. The second gear portion 114 includes a plurality of second teeth 114a and a plurality of second tooth slots 114b. The second teeth 114a protrude relative to the second tooth slots 114b. These second teeth 114a and second tooth slots 114b are staggered and arranged in a ring, such that a second tooth 114a protrudes between two adjacent second tooth slots 114b. In some embodiments, each second tooth 114a includes an upper convex arcuate edge 114a', such that the upper edge of each second tooth 114a has a smooth structure that is not at a right angle.
[0065] The density of the second tooth 114a is different from the density of the first tooth 126a. In some embodiments, the density of the second tooth 114a is less than the density of the first tooth 126a. For example, the number of first teeth 126a may be twice the number of second teeth 114a.
[0066] like Figure 2 As shown, in some embodiments, the column 110 further includes a blank portion 116 and a base plate 118. The blank portion 116 is located on the second gear portion 114 and is located between the first gear portion 126 and the second gear portion 114. The blank portion 116 has a smooth outer surface 116a, that is, the outer surface 116a does not have any protruding or recessed structures. The base plate 118 is located below the second gear portion 114, so the second gear portion 114 is located between the base plate 118 and the blank portion 116. The radial dimension of the base plate 118 may be larger than the maximum radial dimension of the second gear portion 114.
[0067] The metal pillar 200 may be, for example, a die-cast part, and the material may be a metal alloy. The metal pillar 200 covers the outer surface of the plastic pillar 100, thus the metal pillar 200 is arranged around the plastic pillar 100. For example, such as Figure 3 As shown, the metal column 200 covers the first gear portion 126 of the column top 120, as well as the outer surface 116a of the blank portion 116 of the column body 110, the second gear portion 114, and the outer surface 118a of the base plate 118. Therefore, the metal column 200 is embedded in the first tooth groove 126b of the first gear portion 126 and the second tooth groove 114b of the second gear portion 114. The metal column 200 does not cover the top 124 of the column top 120 or the bottom surface 118b of the base plate 118.
[0068] In some embodiments, the plastic column 100 is formed within the metal column 200 using injection molding technology, such that the outer side of the plastic column 100 is joined to the inner side of the metal column 200. Therefore, the outer structural shape of the plastic column 100 matches the inner structural shape of the metal column 200. Please also refer to... Figures 2 to 4Corresponding to the structure of the first gear portion 126 of the top 120 of the plastic column 100, the metal column 200 includes several first protruding structures 210 and first grooves 220. The first protruding structures 210 are correspondingly embedded in the first tooth groove 126b, and the first tooth portion 126a is correspondingly embedded in the first groove 220.
[0069] On the other hand, corresponding to the structure of the second gear portion 114 of the column body 110 of the plastic column 100, the metal column 200 includes several second protrusions 230 and second grooves 240. The second protrusions 230 are correspondingly embedded in the second tooth grooves 114b, and the second teeth 114a are correspondingly embedded in the second grooves 240.
[0070] In some embodiments, the metal post 200 includes an inner boss 250. The inner boss 250 protrudes toward the junction of the top 124 of the post 120 and the first gear portion 126. Since the top 124 is larger than the first gear portion 126 and completely covers it, and the metal post 200 does not cover the top 124, the lower surface 124a of the top 124 can abut against the inner boss 250. That is, the top 124 is located on the inner boss 250. In embodiments where the outer surface 126c of the first gear portion 126 includes a concave arc surface 126c', the inner edge of the inner boss 250 includes a convex arc surface 252, and this convex arc surface 252 engages with the concave arc surface 126c'.
[0071] The first gear portion 126, which is recessed from the top 124, engages with the convex arc surface 252 of the inner boss 250 of the metal pillar 200 via a concave arc surface 126c'. This rounded arc surface design optimizes plastic filling and stress distribution, thus reducing stress at the engagement point between the top 124 and the first gear portion 126 when the plastic pillar 100 shrinks. The first tooth portion 126a and the first tooth groove 126b disperse the contact surface between the first gear portion 126 and the metal pillar 200 into several surfaces, thereby further reducing stress concentration at the engagement point between the top 124 and the first gear portion 126. In this way, the shrinkage rate of the plastic pillar 100 can be reduced.
[0072] In some embodiments, the contours of the first tooth 126a and the second tooth 114a of the plastic column 100, and the first protruding structure 210 and the second protruding structure 230 of the metal column 200, may be spiral-shaped rather than straight up and down. In some exemplary embodiments, the first tooth 126a, the second tooth 114a, the first protruding structure 210, and the second protruding structure 230 may be trapezoidal structures. The trapezoidal tooth structure has a certain degree of flexibility and can better absorb and buffer small relative displacements and stresses. In particular, the area of the second tooth 114a with a sparser arrangement at the bottom can serve as a stress buffer.
[0073] In some embodiments, the first teeth 126a of the first gear portion 126 and the second teeth 114a of the second gear portion 114 are staggered. This staggered arrangement can completely eliminate weak thin surfaces under axial shear, achieving isotropic strength. Specifically, in the high-density first gear portion 126 at the top, the stress distribution at the tooth root and tooth valley is uneven, resulting in local peaks. The staggered arrangement can disrupt the periodicity of stress. When the tooth root in one region is under high stress, the second gear portion 114 in another region that is staggered with it may be under low stress. This allows for a more uniform distribution of stress throughout the volume, preventing local stress from reaching the material limit prematurely. Furthermore, the staggered arrangement of the first teeth 126a and the second teeth 114a forms multiple sets of torque-resisting fulcrums at different angles in the circumferential direction, thus enhancing torsional resistance and providing more directional constraints. That is, when the first teeth 126a and the second teeth 114a are staggered, the locking performance is better than that of the non-staggered arrangement.
[0074] In embodiments where a gap 116 is provided between the first gear portion 126 and the second gear portion 114, the presence of the gap 116 can break the air walls that may be generated by the spiral flow of the plastic melt, providing an opportunity for the plastic melt to converge and reposition. This facilitates the removal of trapped air and improves the problem of low weld line strength in plastic. Furthermore, the sparse and staggered second gear portions 114a can create multiple wide channels for the flow of the plastic melt, thereby significantly reducing flow resistance and allowing for more uniform filling of the plastic melt. In other embodiments, a similar effect can be achieved by providing another gear portion with a different spiral direction in the transition region between the first gear portion 126 and the second gear portion 114.
[0075] In embodiments where the density of the second tooth 114a is less than that of the first tooth 126a, the denser upper first tooth 126a provides more metal-plastic contact surface per unit length, distributing peak shear stress across more first teeth 126a and preventing overloading of individual first teeth 126a that could lead to plastic peeling. The sparser lower second tooth 114a matches the lower stress level, thereby optimizing the material distribution of the plastic column 100 while ensuring sufficient strength. Furthermore, during the filling of the plastic column 100, the denser arrangement of the upper first tooth 126a allows for perfect replication of the fine tooth profile due to the high melt pressure and temperature. On the other hand, the sparser arrangement of the lower second tooth 114a reduces the burden on the flow end of the plastic melt, lowers flow resistance, and prevents insufficient plastic filling due to pressure loss. Moreover, the wide second tooth groove 114b also provides a venting channel, guiding trapped air to the mold venting groove.
[0076] In some embodiments, the first tooth 126a is shorter than the second tooth 114a. The length of the first tooth 126a typically only needs to cover the most critical section where the locking element engages with the plastic pillar 100, and does not need to be excessively long. For example, the length of the first tooth 126a can be approximately 1.5 to 2 times the diameter of the locking element. Each first tooth 126a acts as a rigid anchor point, anchored in the metal pillar 200 covering it. This creates a near-integral rigid connection in the core area of the plastic pillar 100 where it is engaged by the locking element, thereby completely eliminating the possibility of fretting wear and premature loosening of the locking element. Since the high-density first tooth 126a is extremely sensitive to injection pressure, temperature, and mold precision, long-distance filling can easily generate weld lines and trapped air. Therefore, designing the first tooth 126a to be shorter in length can significantly reduce the filling difficulty of the first gear portion 126 and the mold manufacturing risk.
[0077] In some embodiments, the length of the second tooth 114a in the bottom region accounts for more than 50% of the total length of the metal pillar 200 covering the plastic pillar 100. The long stroke and sparse tooth structure of the second tooth 114a allow for large plastic deformation under extreme impacts, such as the stretching and deformation of the first tooth 126a and the second tooth 114a, thus absorbing a large amount of kinetic energy and preventing instantaneous, catastrophic brittle pull-out of the plastic pillar 100 during connection. The long second tooth 114a with a sparse tooth design provides a wide and smooth channel for the flow of the plastic melt, allowing the plastic melt to easily fill this area and push all gas to the end for discharge. In addition, the sparse tooth design of the second tooth 114a also significantly reduces the processing difficulty and cost of the mold core.
[0078] Furthermore, since the metal post 200 is wrapped around the plastic post 100, it facilitates the conduction of static electricity. This design makes the locking fastener 10 very suitable for use on vehicle bodies.
[0079] like Figure 3 and Figure 4 As shown, in some embodiments, the metal column 200 further includes a top wall 260. The top wall 260 is located on the inner boss 250 and surrounds the inner boss 250. The top 124 of the column top 120 of the plastic column 100 is located on the inner boss 250, and the height of the top 124 is lower than the height of the top wall 260. Therefore, the top wall 260 can enclose the components locked in the second locking hole 122 and the first locking hole 112 of the plastic column 100 within its interior, thereby improving the reliability of the locking.
[0080] Mechanism evaluation tests were conducted on the locking fastener 10 and a comparative locking post. Compared to the locking fastener 10, the comparative locking post at least lacks the design of the first gear portion 126 and the concave arc surface 126c' of the outer surface 126c of the first gear portion 126 of the plastic post 100, as well as the structure of the metal post 200 corresponding to these designs of the plastic post 100. After testing, the maximum principal stress of the comparative example was 37.1 MPa, and the maximum principal stress of the locking fastener 10 was 19 MPa. The test results show that the design of the locking fastener 10 can reduce the stress by 49%, demonstrating that the locking fastener 10 has an excellent stress dispersion effect.
[0081] As can be seen from the above embodiments, the first gear portion at the top of the plastic column of the fastener can disperse the contact portion between the plastic column and the metal column into several contact surfaces, thus achieving a stress dispersion effect and reducing the shrinkage rate of the plastic column. Furthermore, the outer surface of the first gear portion includes a concave arc surface extending to the lower surface of the top, and the inner edge of the inner boss of the metal column includes a convex arc surface that can engage with this concave arc surface. The engagement between the top of the column and the convex arc surface of the inner boss of the metal column through the concave arc surface of the first gear portion effectively reduces the stress at the joint between the top and the first gear portion. Moreover, the first tooth of the first gear portion can be firmly anchored in the portion of the metal column covering it, thus significantly enhancing the tensile and torsional resistance of the plastic column.
[0082] Although this disclosure has been shown above by way of embodiments, it is not intended to limit this disclosure. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of this disclosure. Therefore, the scope of protection of this disclosure shall be determined by the appended claims.
Claims
1. A locking device, characterized in that, The firmware includes: A plastic column, comprising: A column body having a first locking hole extending along a length direction of the column body; and A column top, disposed on the column body, and having a second locking hole aligned with the first locking hole, wherein the column top includes a top and a first gear portion engaging a lower surface of the top, the first gear portion including a plurality of first teeth and a plurality of first tooth grooves, the first teeth and the first tooth grooves being arranged in an alternating ring; and A metal column covers one outer side of the plastic column and is embedded in the first tooth grooves.
2. The locking device as described in claim 1, characterized in that: One outer surface of the first gear portion includes a concave arc surface that extends to the lower surface of the top; and The metal column includes an inner boss, and an inner edge of the inner boss includes a convex arc surface that engages with the concave arc surface.
3. The locking device as described in claim 2, characterized in that, The metal column includes a top wall that is located on and surrounds the inner boss.
4. The locking device as described in claim 3, characterized in that, The top is located on the inner protrusion, and the height of the top is lower than the height of the top wall.
5. The locking device as described in claim 1, characterized in that, The column includes a second gear section, wherein the second gear section includes a plurality of second teeth and a plurality of second tooth grooves, the second teeth and the second tooth grooves being arranged in an alternating ring.
6. The locking device as described in claim 5, characterized in that, The column also includes: A blank portion, located between the first gear portion and the second gear portion, wherein the blank portion has a smooth outer surface; and A base plate is located below the second gear section.
7. The locking device as described in claim 5, characterized in that, The first teeth and the second teeth are arranged alternately.
8. The locking device as described in claim 5, characterized in that, The density of the first teeth is twice the density of the second teeth.
9. The locking device as described in claim 8, characterized in that, The length of the first teeth is less than the length of the second teeth.
10. The locking device as described in claim 5, characterized in that, Each of the first teeth and each of the second teeth is a trapezoidal structure.
11. The locking device as described in claim 5, characterized in that, Each of these second teeth includes an upward-convex arcuate edge.