Insert structure for improving tolerance of low-cost bushing and mold

Abstract

The application discloses a low-cost insert structure for improving bushing tolerance and a mold, which comprises a positioning column body provided with a limiting hole at the top; a movable insert is movably assembled with the limiting hole, and the movable insert is provided with elastic potential energy along the depth direction away from the limiting hole, and the upper part of the movable insert is exposed from the limiting hole; wherein, along the depth direction of the limiting hole, the movable insert is sequentially provided with an upper cylindrical segment, a circular truncated cone segment and a lower cylindrical segment, the outer diameter of the upper cylindrical segment is smaller than that of the lower cylindrical segment, and the outer diameter of the circular truncated cone segment gradually increases; the outer wall at the junction of the circular truncated cone segment and the upper cylindrical segment is transitioned through an inner fillet; the shaft end edge of the upper cylindrical segment away from the circular truncated cone segment is provided with an outer fillet; when the movable insert is located at the limit position away from the bottom surface of the limiting hole, the junction of the circular truncated cone segment and the lower cylindrical segment is flush with the opening edge of the limiting hole. The movable insert conical surface floating compensation bushing tolerance is adopted, so that the size precision of the bushing is reduced, the placement difficulty of the bushing is reduced, and the cost of the bushing is also reduced.

Description

Technical Field

[0001] This invention relates to the field of mold inserts, and more specifically to a low-cost insert structure and mold for improving bushing tolerances. Background Technology

[0002] Metal bushing composite components have been applied in many fields. One application is in embedded threaded sleeve assemblies, such as metal threaded sleeves embedded in engineering plastic parts. Another application is in electrical terminal components, such as bushings embedded in connector plastic housings with conductive areas exposed at both ends. Composite material parts are manufactured by placing the metal bushings into injection molds.

[0003] The bushing is typically positioned within the mold by placing it on a positioning post inside the mold, and then pressing down the front mold to close the mold and form the bushing. Assuming the positioning post diameter is Φ5.59 and the bushing inner diameter tolerance is Φ5.60 (+0.04 / 0), the maximum offset of the bushing center relative to the positioning post center is 0.025mm. In this case, the bushing position after forming can meet the product requirements, but it requires a high tolerance for the bushing's inner diameter. High precision requirements will lead to an increase in the unit cost of the bushing. Summary of the Invention

[0004] The problem to be solved by the present invention is to provide a low-cost insert structure and mold for improving bushing tolerance.

[0005] To address the above problems, this invention provides a low-cost insert structure and mold for improving bushing tolerances. The technical solution adopted by this invention to solve its technical problems and achieve the above objectives is as follows:

[0006] A low-cost insert structure for improving bushing tolerances includes: a positioning column with a limiting hole at the top; and a movable insert movably assembled with the limiting hole, the movable insert possessing elastic potential energy along the depth direction away from the limiting hole, the upper part of the movable insert protruding from the limiting hole; wherein, along the depth direction of the limiting hole, the movable insert sequentially comprises an upper cylindrical section, a frustum section, and a lower cylindrical section, the outer diameter of the upper cylindrical section being smaller than the outer diameter of the lower cylindrical section, and the outer diameter of the frustum section gradually increasing; the outer wall at the junction of the frustum section and the upper cylindrical section is transitioned by an inner fillet; the axial end edge of the upper cylindrical section away from the frustum section has an outer fillet; when the movable insert is located at the extreme position far from the bottom surface of the limiting hole, the junction of the frustum section and the lower cylindrical section is flush with the opening edge of the limiting hole.

[0007] As a further improvement of the present invention, the length of the movement range of the movable insert along the axial direction of the limiting hole is equal to the axial length of the frustum segment.

[0008] As a further improvement of the present invention, the radius of the outer fillet is 0.3 mm; and / or the radius of the inner fillet is 5.0 mm; and / or the cone angle of the frustum segment is 10°.

[0009] As a further improvement of the present invention, a process hole is recessed at one end of the movable insert, the axis of the process hole coincides with the axis of the movable insert, and the length of the process hole is greater than the sum of the lengths of the upper cylindrical section and the frustum section.

[0010] As a further improvement of the present invention, the limiting hole of the positioning column includes an upper hole and a lower blind hole coaxially connected. The inner diameter of the upper hole is larger than the inner diameter of the lower blind hole. The movable insert is located in the upper hole, and a compression spring is provided in the lower blind hole. One end of the compression spring contacts one end of the movable insert.

[0011] As a further improvement of the present invention, the movable insert has an oblong hole in the lower cylindrical section, the length direction of the oblong hole is parallel to the axis of the movable insert, and a radially extending limiting pin is fixed inside the limiting hole of the positioning column, the limiting pin being located inside the oblong hole.

[0012] As a further improvement of the present invention, the distance between the two centers of the waist-shaped hole is less than the axial length of the frustum segment; the axial length of the compression spring in the uncompressed state is greater than the axial length of the lower blind hole.

[0013] As a further improvement of the present invention, the axial length of the frustum segment is one-third to one-half of the axial length of the upper cylindrical segment.

[0014] As a further improvement of the present invention, the end of the positioning column opposite to the limiting hole has an integral radially expanded base.

[0015] Secondly, a mold comprising the aforementioned low-cost insert structure for improving bushing tolerances.

[0016] The advantages of using the low-cost insert structure for improving bushing tolerances in this application are:

[0017] First, it can significantly improve the positioning accuracy of the bushing. The movable insert can float axially under the action of elastic potential energy, and the upper cylindrical section, the gradually expanding frustum section and the lower cylindrical section form a unique stepped geometric guide structure. When the bushing is inserted, the conical surface of the frustum section can adaptively compensate for the fluctuation of the bushing's inner diameter tolerance, so that the inner wall of the bushing always keeps in contact with the conical surface, effectively eliminating the radial clearance in traditional positioning and ensuring that the bushing is automatically guided during the mold closing process.

[0018] Secondly, it enhances structural reliability and assembly safety. The inner rounded corner transition at the junction of the frustum section and the upper cylindrical section avoids the risk of cracking due to stress concentration. The outer rounded corner at the end of the upper cylindrical section forms an introductory chamfer, preventing scratches during bushing insertion. This double rounded corner design extends the insert's lifespan and protects the surface of the precision bushing.

[0019] Finally, when the movable insert is at its highest position, the junction of the frustum section and the lower cylindrical section is perfectly flush with the opening of the limiting hole, a feature that provides precise stroke control. This ensures that the effective working area of ​​the frustum section is fully exposed while preventing the movable insert from overextending and causing wobble, providing a stable support reference for the bushing, which is equivalent to ensuring stability through mechanical limiting. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a top view of one implementation method for improving the front positioning post;

[0022] Figure 2 This is an AA cross-sectional view of one embodiment of improving the front positioning post;

[0023] Figure 3 This is a magnified view of section B in one embodiment of improving the front positioning post;

[0024] Figure 4 This is an application diagram illustrating one method of improving the front positioning post;

[0025] Figure 5 This is a top view of one embodiment of the present invention;

[0026] Figure 6 This is a CC cross-sectional view of one embodiment of the present invention;

[0027] Figure 7 This is a partial enlarged view of point D in one embodiment of the present invention;

[0028] Figure 8 This is an application diagram of one embodiment of the present invention;

[0029] Figure 9 This is a top view of a bushing according to one embodiment of the present invention;

[0030] Figure 10 This is a perspective view of a bushing according to one embodiment of the present invention;

[0031] Figure 11 This is a front view of one embodiment of the bushing before improvement;

[0032] Figure 12 This is a front view of a bushing according to one embodiment of the present invention.

[0033] 1-Bushing; 101-Axial cavity; 102-Circumferential rib; 103-Circumferential groove; 2-Improved positioning post; 201-Upper shaft section; 202-Lower shaft section; 3-Modible positioning post; 4-Positioning post body; 401-Upper hole; 402-Lower blind hole; 403-Base; 5-Modible insert; 501-Oval hole; 502-Process thread hole; 503-Outer fillet; 504-Upper cylindrical section; 505-Inner fillet; 506-Frustum section; 507-Lower cylindrical section; 6-Linear spring; 7-Limiting pin; 8-Lower pressure post. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments:

[0035] To achieve the objectives of this invention, a low-cost insert structure for improving bushing tolerances is provided, comprising: a positioning post 4 with a limiting hole at its top; and a movable insert 5, movably assembled with the limiting hole, the movable insert 5 possessing elastic potential energy along a direction opposite to the depth of the limiting hole, the upper portion of the movable insert 5 protruding from the limiting hole. Wherein, along the depth direction of the limiting hole, as... Figure 7 As shown, the movable insert 5 sequentially comprises an upper cylindrical section 504, a frustum section 506, and a lower cylindrical section 507. The outer diameter of the upper cylindrical section 504 is smaller than that of the lower cylindrical section 507, and the outer diameter of the frustum section 506 gradually increases. The outer wall at the junction of the frustum section 506 and the upper cylindrical section 504 is transitioned by an inner fillet 505. The axial end edge of the upper cylindrical section 504 away from the frustum section 506 has an outer fillet 503. When the movable insert 5 is in its extreme position far from the bottom surface of the limiting hole, the junction of the frustum section 506 and the lower cylindrical section 507 is flush with the opening edge of the limiting hole.

[0036] The beneficial effects of adopting the above technical solution are as follows: This structure achieves adaptive positioning of the bushing 1 through the three-segment design of the movable insert 5. The upper cylindrical segment 504 facilitates the initial insertion of the bushing 1, the gradually expanding frustum segment 506 automatically compensates for the fluctuation of the inner diameter tolerance of the bushing 1, and the lower cylindrical segment 507 provides stable support. The inner fillet 505 reduces stress concentration, and the outer fillet 503 prevents the bushing 1 from being scratched. The movable insert 5 floats under the drive of elastic potential energy. When it is in the highest position, the junction of the frustum segment 506 and the lower cylindrical segment 507 is flush with the opening of the limiting hole, forming precise stroke control.

[0037] In some other embodiments of the present invention, the length of the movement range of the movable insert 5 along the axial direction of the limiting hole is equal to the axial length of the frustum segment 506.

[0038] The beneficial effects of adopting the above technical solution are: the length of the axial movement range of the movable insert 5 is limited to the 506 axis length of the frustum section, ensuring that the conical surface participates in tolerance compensation throughout the entire process, and avoiding positioning deviation caused by insufficient or excessive displacement.

[0039] In other embodiments of the invention, the radius of the outer fillet 503 is 0.3 mm. The radius of the inner fillet 505 is 5.0 mm. The cone angle of the frustum segment 506 is 10°.

[0040] The beneficial effects of adopting the above technical solution are: the 0.3mm outer radius 503 optimizes the smoothness of insertion and reduces the positioning accuracy required when inserting bushing 1. The 5.0mm inner radius 505 disperses the stress at the connection between the frustum section 506 and the upper cylindrical section 504. The 10° cone angle is relatively small, achieving a balance between tolerance compensation capability and structural rigidity.

[0041] In one embodiment, the basic inner diameter of the bushing is defined as D. 衬 The lower deviation of the inner diameter of bushing 1 is 0, the upper deviation of the inner diameter of bushing 1 is Δ (Δ>0), and the outer diameter of the upper cylindrical section 504 is D. 上 The outer diameter of the lower cylindrical section 507 is D. 下 The cone angle of frustum segment 506 is α, and the axial length of frustum segment 506 is L. 台 The axial length of the upper cylindrical segment 504 is L. 上 And satisfy the following relationship:

[0042] D 上 =D 衬 -0.005mm to D 衬 -0.015mm;

[0043] D 下 =(D 衬 +Δ)+0.10mm to (D 衬 +Δ)+0.15mm;

[0044] α = 8° to 12°;

[0045] L 台 =(1 / 3)L 上 Up to (1 / 2)L 上 .

[0046] In addition, regarding the optimization of data, taking the basic inner diameter of the bushing as Φ5.60, the lower deviation of the inner diameter of the bushing as 0, and the upper deviation of the inner diameter of the bushing as 0.08 as an example, the outer diameter of the upper cylindrical section 504 is Φ5.59 (0 / -0.01), while the outer diameter of the lower cylindrical section 507 is Φ5.80 (0 / -0.01).

[0047] In some other embodiments of the present invention, a process hole 502 is recessed at one end of the movable insert 5, the axis of the process hole 502 coincides with the axis of the movable insert 5, and the length of the process hole 502 is greater than the sum of the lengths of the upper cylindrical section 504 and the frustum section 506.

[0048] The bottom of the process hole 502 has a tapered bottom, and the inner wall of the process hole 502 has an internal thread.

[0049] The beneficial effects of adopting the above technical solution are as follows: the depth of the process hole 502 exceeds the total axial length of the upper cylindrical section 504 and the frustum section 506, ensuring the stability of the axis of the movable insert 5 during machining; the tapered bottom of the hole facilitates chip removal and provides space for thread machining; the process hole 502 can be assembled with external bolts, facilitating the operation of the movable insert 5 by external actuating mechanisms.

[0050] like Figure 6 As shown, in some other embodiments of the present invention, the limiting hole of the positioning column 4 includes an upper hole 401 and a lower blind hole 402 coaxially connected. The inner diameter of the upper hole 401 is larger than the inner diameter of the lower blind hole 402. The movable insert 5 is located in the upper hole 401. A compression spring, i.e. a linear spring 6, is provided in the lower blind hole 402. One end of the compression spring contacts one end of the movable insert 5.

[0051] In addition, the linear spring 6 is preferably a Φ4.0*10 linear spring 6.

[0052] The beneficial effects of adopting the above technical solution are: the upper hole 401 provides a guiding space for the movable insert 5, the lower blind hole 402 encapsulates the linear spring 6 to prevent displacement, and the spring force direction is consistent with the pressing direction of the bushing 1, ensuring positioning reliability.

[0053] In some other embodiments of the present invention, the movable insert 5 has a waist-shaped hole 501 in the lower cylindrical section 507, the length direction of the waist-shaped hole 501 is parallel to the axis of the movable insert 5, and a radially extending limiting pin 7 is fixed inside the limiting hole of the positioning column 4, the limiting pin 7 being located inside the waist-shaped hole 501.

[0054] The beneficial effects of adopting the above technical solution are: the combination of the waist-shaped hole 501 and the limiting pin 7 restricts the circumferential rotation of the movable insert 5 while maintaining the axial limit position, ensuring that the conical surface of the frustum section 506 is always aligned with the inner wall of the bushing 1.

[0055] In other embodiments of the invention, the distance between the two centers of the oblong hole 501 is less than the axial length of the frustum section 506. The axial length of the compression spring in its uncompressed state is greater than the axial length of the lower blind hole 402.

[0056] The beneficial effects of adopting the above technical solution are: the length of the waist-shaped hole 501 is less than the shaft length of the frustum section 506 to prevent excessive stroke; the free length of the linear spring 6 is greater than the depth of the lower blind hole 402, thus maintaining effective elastic force at all times.

[0057] In some other embodiments of the invention, the axial length of the frustum segment 506 is one-third to one-half of the axial length of the upper cylindrical segment 504.

[0058] Figure 6The travel distance is 1.00mm.

[0059] The beneficial effects of adopting the above technical solution are: the length of the 506 axis of the frustum section is set to be a small half of the length of the 504 axis of the upper cylindrical section, which optimizes the effective working area of ​​the conical surface and balances the positioning accuracy and structural strength.

[0060] In one implementation, the frustum section 506 is designed as a multi-stage stepped conical surface. That is, the frustum section 506 is divided axially into two or three sub-conical surfaces with different cone angles, for example: an upper cone angle of 6°, a middle cone angle of 10°, and a lower cone angle of 14°. Furthermore, a micro-rounded transition with a radius R of 0.5 mm is used between each sub-conical surface. Additionally, a cooling channel is added inside the movable insert 5, with the cooling channel inlet located at the bottom of the process thread hole 502 and the outlet located on the side wall of the lower cylindrical section 507.

[0061] The multi-stage conical surface forms a progressive compensation mechanism. The upper section with a small cone angle is adapted to the precision bushing 1, while the lower section with a large cone angle is compatible with the coarse tolerance bushing 1, which improves compatibility compared to the original single cone angle structure. In addition, it also extends the service life of the frustum section 506 because the micro-rounded corner transition disperses the stress concentration of the multi-stage conical surface.

[0062] The design of the cooling channels can, to some extent, eliminate the effects of thermal deformation. During injection molding, the heat of the molten plastic is conducted to the moving insert 5 through the bushing 1. The cooling channels are circulated with constant-temperature oil, which can control the working temperature of the insert within a certain range and avoid the positioning drift caused by thermal expansion in traditional structures.

[0063] like Figure 6 As shown, in some other embodiments of the present invention, the end of the positioning column 4 facing away from the limiting hole has an integrally radially expanded base 403.

[0064] The beneficial effects of adopting the above technical solution are: the base 403, which is integrally formed at the bottom of the positioning column 4, enhances the installation stability, resists the impact force of injection molding, and prevents overall displacement.

[0065] In addition, regarding material hardness, the hardness of the movable insert 5 is greater than that of the positioning post 4.

[0066] This application also provides a mold, including the insert structure described above for improving bushing tolerances at low cost.

[0067] The mold is an injection mold. The insert structure, which improves the bushing tolerance at low cost, is used to temporarily fix the bushing 1. Molten plastic is injected into the injection mold and wraps the side of the bushing 1, i.e. the circumferential surface. Finally, it is demolded after solidification.

[0068] The beneficial effects of adopting the above technical solution are: the mold using the insert structure of this application can directly obtain the positioning capability of high-precision bushing 1, and is compatible with bushings 1 with larger tolerances to reduce the production cost of composite injection molded parts.

[0069] like Figure 8 As shown, Figure 8 The downward pressure column 8 represents the front mold pressing down on the bushing after the mold is closed. Figure 8 The dotted lines in the figure represent movable inserts, and the top of the movable inserts is fitted with bushing 1.

[0070] like Figure 9 and Figure 10 The bushing 1 shown includes an axially extending cavity 101. Depending on the radial thickness of the bushing 1, it also includes circumferential ribs 102 and circumferential grooves 103, with two circumferential ribs 102 forming a circumferential groove 103. Molten plastic also enters the circumferential groove. The two circumferential ribs 102 and the circumferential groove 103 of the bushing 1 each have equal axial lengths.

[0071] like Figure 8 As shown, the difference between the radius of the positioning column 4 and the radius of the movable insert 5 is greater than the radial thickness of the bushing 1.

[0072] like Figures 1 to 4 The diagram shows an embodiment before improvement, specifically the positioning post 2. The bushing is placed on the 5.59mm diameter positioning post within the mold, and then the front mold is pressed down to close the mold and form the bushing. If the bushing's inner diameter tolerance is Φ5.60 (+0.04 / 0), the maximum offset of the bushing center relative to the positioning post center is 0.025mm. The position of the formed bushing meets product requirements, but it places high demands on the bushing's inner diameter tolerance, leading to an increase in the bushing's unit price. If a bushing with an inner diameter tolerance of Φ5.60 (+0.08 / 0) is chosen to reduce the bushing's unit price, the maximum offset of the bushing center relative to the positioning post center is 0.045mm. The position of the formed bushing may then fail to meet the product's precision requirements for bushing position.

[0073] The bushing is positioned using a locating pin with a diameter of 5.59mm, resulting in a simple and reliable structure. The disadvantage is that it requires a relatively high inner diameter for the bushing, leading to increased costs.

[0074] like Figures 5 to 10 This is an improved embodiment, namely the improved movable positioning post 3 of this application. The bushing is placed on the movable insert of the positioning post, and the front mold of the mold is pressed down to close the mold and form the product. At this time, because the movable insert has a slope and the bushing can automatically guide the position of the positioning post, the offset of the bushing center relative to the center of the movable insert is 0mm, and the positioning accuracy is better. The position of the bushing after forming can also meet the product requirements, but the requirement for the inner diameter tolerance of the bushing does not need to be very high. It can be enlarged to Φ5.60 (+0.08 / 0), thereby reducing the unit price of bushing purchase and making the product more accurate.

[0075] The principle is to use inclined planes and movable inserts with vertical movement. When the front mold is pressed down, the bushing can automatically guide the position of the positioning post, thereby achieving centering and positioning.

[0076] The advantages are higher positioning accuracy and lower requirements for the inner diameter tolerance of the bushing, thereby reducing production costs.

[0077] Figure 11 The inner diameter tolerance of the bushing is Φ5.60 (+0.04 / 0). Figure 11 This is the bushing that needs to be used before the improvement. Figure 12 The improved bushing 1 can be selected according to the present invention, and the inner diameter tolerance of bushing 1 is Φ5.60 (+0.08 / 0). Figure 12 The inner diameter fluctuation range of bushing 1 can be larger, and the requirement for the inner diameter accuracy of bushing 1 is not so high.

[0078] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A low-cost insert structure for improving bushing tolerances, characterized in that, include: The positioning column has a limiting hole at the top; A movable insert is movably assembled with a limiting hole, the movable insert having elastic potential energy in a direction opposite to the depth of the limiting hole, and the upper part of the movable insert protruding from the limiting hole. Along the depth direction of the limiting hole, the movable insert sequentially comprises an upper cylindrical section, a frustum section, and a lower cylindrical section. The outer diameter of the upper cylindrical section is smaller than that of the lower cylindrical section, and the outer diameter of the frustum section gradually increases. The outer wall at the junction of the frustum section and the upper cylindrical section is transitioned by an inner rounded corner; The upper cylindrical section has an outer fillet at the axial end edge that is away from the frustum section; When the movable insert is at its extreme position far from the bottom surface of the limiting hole, the junction of the frustum section and the lower cylindrical section is flush with the opening edge of the limiting hole. The positioning post includes a limiting hole with an upper hole and a lower blind hole connected coaxially. The inner diameter of the upper hole is larger than the inner diameter of the lower blind hole. The movable insert is located in the upper hole. A compression spring is provided in the lower blind hole. One end of the compression spring is in contact with one end of the movable insert. The movable insert has an oblong hole in its lower cylindrical section. The length direction of the oblong hole is parallel to the axis of the movable insert. A radially extending limiting pin is fixed inside the limiting hole of the positioning column. The limiting pin is located inside the oblong hole.

2. The low-cost insert structure for improving bushing tolerances according to claim 1, characterized in that: The length of the movement range of the movable insert along the axial direction of the limiting hole is equal to the axial length of the frustum segment.

3. The low-cost insert structure for improving bushing tolerances according to claim 1, characterized in that: The radius of the outer fillet is 0.3 mm; and / or The radius of the inner fillet is 5.0 mm; and / or The cone angle of the frustum section is 10°.

4. The low-cost insert structure for improving bushing tolerances according to claim 1, characterized in that: The movable insert has a recessed process hole at one end, the axis of which coincides with the axis of the movable insert, and the length of the process hole is greater than the sum of the lengths of the upper cylindrical section and the frustum section.

5. The low-cost insert structure for improving bushing tolerances according to claim 1, characterized in that: The distance between the two centers of the waist-shaped hole is less than the axial length of the frustum section; the axial length of the compression spring in its uncompressed state is greater than the axial length of the lower blind hole.

6. The low-cost insert structure for improving bushing tolerances according to claim 1, characterized in that: The axial length of the frustum segment is one-third to one-half of the axial length of the upper cylindrical segment.

7. The low-cost insert structure for improving bushing tolerances according to claim 1, characterized in that: The end of the positioning column opposite to the limiting hole has an integral radially expanded base.

8. A mold, characterized in that, Including the low-cost insert structure for improving bushing tolerances as described in any one of claims 1 to 7.

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