Low-cost insert structure capable of improving tolerance of bushing and mold

Abstract

The invention discloses a low-cost insert structure capable of improving bushing tolerance and a mold. The insert structure comprises a positioning column body, and the top of the positioning column body is provided with a limiting hole; the movable insert is movably assembled with the limiting hole, the movable insert has elastic potential energy in the direction deviating from the depth direction of the limiting hole, and the upper part of the movable insert is exposed out of the limiting hole; the movable insert is sequentially provided with an upper cylindrical section, a circular truncated cone section and a lower cylindrical section in the depth direction of the limiting hole, the outer diameter of the upper cylindrical section is smaller than that of the lower cylindrical section, and the outer diameter of the circular truncated cone section is gradually increased; the outer wall of the junction of the circular truncated cone section and the upper cylindrical section is transited through an inner fillet; the shaft end edge, deviating from the circular truncated cone section, of the upper cylindrical section is provided with an outer fillet; when the movable insert is located at the limiting position away from the bottom face of the limiting hole, the junction of the circular truncated cone section and the lower cylindrical section is flush with the opening edge of the limiting hole. The tolerance of the bushing is compensated by adopting the conical surface of the movable insert in a floating manner, so that the dimensional accuracy 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] The invention relates to the field of mold inserts, and in particular to an insert structure and a mold for improving bushing tolerance at low cost. Background Art

[0002] Composite components made of metal bushings have been applied in a wide range of fields. One application is embedded threaded insert assemblies, such as metal threaded inserts embedded in engineering plastic parts. Another application is electrical terminal components, such as bushings embedded in connector plastic housings, with conductive areas exposed at both ends. Composite components are produced by placing metal bushings in injection molds.

[0003] The bushing is usually positioned in the mold by placing it on the positioning column in the mold, and then pressing the front mold down to close the mold. At this time, assuming that the diameter of the positioning column is Φ5.59 and the inner diameter tolerance of the bushing is Φ5.60 (+0.04 / 0), the maximum offset of the bushing center relative to the center of the positioning column is 0.025mm. At this time, the position of the bushing after molding can meet the product requirements, but there are higher requirements for the inner diameter tolerance of the bushing. 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 an insert structure and a mold which can improve the bushing tolerance at a low cost.

[0005] To solve the above problems, the present invention provides an insert structure and a mold for improving bushing tolerance at a low cost. To achieve the above objectives, the technical solution adopted by the present invention to solve the technical problems is: A low-cost insert structure for improving bushing tolerance includes: a positioning cylinder with a limiting hole on the top; a movable insert movably assembled with the limiting hole, the movable insert having 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 has an upper cylindrical section, a frustum section, and a lower cylindrical section in sequence, the outer diameter of the upper cylindrical section is smaller than the outer diameter of the lower cylindrical section, and the outer diameter of the frustum section gradually increases; the outer wall of the junction of the frustum section and the upper cylindrical section is transitioned through 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 away 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.

[0006] As a further improvement of the present invention, the length of the moving range of the movable insert along the axial direction of the limiting hole is equal to the axial length of the frustum segment.

[0007] As a further improvement of the present invention, the fillet radius of the outer fillet is 0.3 mm; and / or the fillet radius of the inner fillet is 5.0 mm; and / or the cone angle of the frustum segment is 10°.

[0008] As a further improvement of the present invention, a process hole is recessed at one axial end of the movable insert, the axis of the process hole coincides with the axis of the movable insert, and the axial length of the process hole is greater than the sum of the axial lengths of the upper cylindrical section and the frustum section.

[0009] 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 is in contact with one end of the movable insert.

[0010] As a further improvement of the present invention, the movable insert has a waist-shaped hole in the lower cylindrical section, the length direction of the waist-shaped hole is parallel to the axis of the movable insert, and a radially extending limit pin is fixed inside the limit hole of the positioning column, and the limit pin is located in the waist-shaped hole.

[0011] As a further improvement of the present invention, the distance between the two centers of the waist-shaped hole is smaller than the axial length of the truncated cone section; the axial length of the compression spring in an uncompressed state is greater than the axial length of the lower blind hole.

[0012] As a further improvement of the present invention, the axial length of the frustum section is one third to one half of the axial length of the upper cylindrical section.

[0013] As a further improvement of the present invention, the end of the positioning column away from the limiting hole is provided with an integral radially expanded base.

[0014] In a second aspect, a mold includes the above insert structure for improving bushing tolerance at low cost.

[0015] The beneficial effects of adopting the low-cost insert structure for improving bushing tolerance of the present application are: First, it significantly improves bushing positioning accuracy. The movable insert, driven by elastic potential energy, allows axial floating. 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 frustum section's tapered surface adaptively compensates for fluctuations in the bushing's inner diameter tolerance, ensuring constant contact between the bushing's inner wall and the tapered surface. This effectively eliminates the radial clearance encountered in traditional positioning and ensures automatic bushing guidance during mold closing.

[0016] Secondly, it enhances structural reliability and assembly safety. The internal fillet at the junction of the truncated cone and the upper cylindrical section reduces the risk of cracks caused by stress concentration. The external fillet at the end of the upper cylindrical section forms a lead-in chamfer, preventing scratches during bushing insertion. This dual fillet design extends the life of the insert while protecting the precision bushing surface.

[0017] Finally, when the movable insert is in its highest position, the junction of the conical section and the lower cylindrical section is perfectly aligned with the opening of the limit hole. This feature ensures precise stroke control. This ensures that the effective working area of ​​the conical section is fully exposed, while preventing the movable insert from overextending and causing deflection. This provides a stable support base for the bushing, effectively guaranteeing stability through mechanical limiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a top view of an embodiment of an improved front positioning column; Figure 2 This is an AA cross-sectional view of an improved front positioning column embodiment; Figure 3 This is a partial enlarged view of point B of an improved implementation method of the front positioning column; Figure 4 This is an application diagram of an implementation method for improving the front positioning column; Figure 5 is a top view of an embodiment of the present invention; Figure 6 1 is a CC cross-sectional view of an embodiment of the present invention; Figure 7 It is a partial enlarged view of point D of one embodiment of the present invention; Figure 8 This is a schematic diagram of an application of an embodiment of the present invention; Figure 9 is a top view of a bushing according to an embodiment of the present invention; Figure 10 is a perspective view of a bushing according to an embodiment of the present invention; Figure 11 This is a front view of an embodiment of the bushing before improvement; Figure 12 It is a front view of a bushing according to one embodiment of the present invention.

[0020] 1-Bushing; 101-Axial cavity; 102-Circumferential rib; 103-Circumferential groove; 2-Improved front positioning column; 201-Upper shaft section; 202-Lower shaft section; 3-Movable positioning column; 4-Positioning column; 401-Upper hole; 402-Lower blind hole; 403-Base; 5-Movable insert; 501-Waist-shaped hole; 502-Process tooth hole; 503-External fillet; 504-Upper cylindrical section; 505-Inner fillet; 506-Frustum section; 507-Lower cylindrical section; 6-Linear spring; 7-Limiting pin; 8-Lower pressure column. DETAILED DESCRIPTION

[0021] The present invention will be described in further detail below with reference to specific embodiments: In order to achieve the purpose of the present invention, a low-cost insert structure for improving bushing tolerance is provided, comprising: a positioning column 4, with a limiting hole on the top. A movable insert 5 is movably assembled with the limiting hole, and the movable insert 5 has elastic potential energy in the depth direction away from the limiting hole, and the upper part of the movable insert 5 is exposed from the limiting hole. Figure 7 As shown, the movable insert 5 comprises, in order, an upper cylindrical section 504, a frustoconical 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, while the outer diameter of the frustoconical section 506 gradually increases. The outer wall at the junction of the frustoconical section 506 and the upper cylindrical section 504 transitions to an inner fillet 505. The axial edge of the upper cylindrical section 504 facing away from the frustoconical section 506 has an outer fillet 503. When the movable insert 5 is in its extreme position away from the bottom surface of the stop hole, the junction of the frustoconical section 506 and the lower cylindrical section 507 is flush with the opening edge of the stop hole.

[0022] The beneficial effects of the above technical solution are as follows: This structure achieves adaptive positioning of the bushing 1 through the three-stage design of the movable insert 5. The upper cylindrical section 504 facilitates initial insertion of the bushing 1, the gradually expanding conical section 506 automatically compensates for fluctuations in the bushing 1's inner diameter tolerance, and the lower cylindrical section 507 provides stable support. The inner fillet 505 reduces stress concentration, and the outer fillet 503 prevents scratches on the bushing 1. The movable insert 5 floats under the influence of elastic potential energy. When in its highest position, the junction of the conical section 506 and the lower cylindrical section 507 is flush with the opening of the limit hole, achieving precise stroke control.

[0023] In some other embodiments of the present invention, the length of the moving range of the movable insert 5 along the axial direction of the limiting hole is equal to the axial length of the frustum section 506 .

[0024] The beneficial effect of adopting the above technical solution is that the axial motion range length of the movable insert 5 is limited to the axial length of the frustum section 506, ensuring that the cone surface participates in tolerance compensation throughout the entire process and avoiding positioning deviation caused by insufficient or excessive displacement.

[0025] In some other embodiments of the present invention, the fillet radius of the outer fillet 503 is 0.3 mm, the fillet radius of the inner fillet 505 is 5.0 mm, and the cone angle of the frustum section 506 is 10°.

[0026] The beneficial effects of adopting the above technical solution are: 0.3mm outer fillet 503 optimizes smooth insertion and reduces the positioning accuracy required when inserting the bushing 1. 5.0mm inner fillet 505 disperses stress at the connection between the frustum section 506 and the upper cylindrical section 504. The smaller 10° taper angle strikes a balance between tolerance compensation and structural rigidity.

[0027] In one embodiment, the inner diameter of the bushing is basically D 衬 The lower deviation of the inner diameter of the bushing 1 is 0, the upper deviation of the inner diameter of the 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 the frustum section 506 is α, and the axis length of the frustum section 506 is L 台 , the axial length of the upper cylindrical section 504 is L 上 , and the following relations are satisfied: D 上 =D 衬 -0.005mm to D 衬 -0.015mm; D 下 =(D 衬 +Δ)+0.10mm to (D 衬 +Δ)+0.15mm; α = 8° to 12°; L 台 =(1 / 3)L 上 to (1 / 2)L 上 .

[0028] In addition, in terms of data optimization, taking the basic size of the 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), and the outer diameter of the lower cylindrical section 507 is Φ5.80 (0 / -0.01).

[0029] In other embodiments of the present invention, a process hole 502 is recessed at one axial end of the movable insert 5, the axis of the process hole 502 coincides with the axis of the movable insert 5, and the axial length of the process hole 502 is greater than the sum of the axial lengths of the upper cylindrical section 504 and the frustum section 506.

[0030] The bottom of the process thread hole 502 has a conical bottom, and the inner wall of the process thread hole 502 has an internal thread.

[0031] The advantages of this technical solution are: the depth of the process hole 502 exceeds the combined axial length of the upper cylindrical section 504 and the frustoconical section 506, ensuring the axial stability of the movable insert 5 during machining. The tapered hole bottom facilitates chip removal and reserves space for threading. The process hole 502 can be assembled with an external bolt, facilitating the operation of the movable insert 5 by an external actuator.

[0032] 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 that are 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, and a compression spring, i.e., a linear spring 6, is provided in the lower blind hole 402, and one end of the compression spring is in contact with one end of the movable insert 5.

[0033] In addition, the linear spring 6 is preferably a linear spring 6 of Φ4.0*10.

[0034] The beneficial effects of adopting the above technical solution are: the upper hole 401 provides a guide space for the movable insert 5, the lower blind hole 402 encapsulates the linear spring 6 to prevent deviation, and the direction of the elastic force is consistent with the pressing direction of the bushing 1, ensuring positioning reliability.

[0035] In other embodiments of the present invention, the movable insert 5 has a waist-shaped hole 501 in the lower cylindrical section 507, and the length direction of the waist-shaped hole 501 is parallel to the axis of the movable insert 5. A radially extending limiting pin 7 is fixed inside the limiting hole of the positioning column 4, and the limiting pin 7 is located in the waist-shaped hole 501.

[0036] The beneficial effect of adopting the above technical solution is that the waist-shaped hole 501 and the limit pin 7 limit 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.

[0037] In some other embodiments of the present invention, the distance between the two centers of the waist-shaped hole 501 is smaller than the axial length of the truncated cone section 506. The axial length of the compression spring in an uncompressed state is greater than the axial length of the lower blind hole 402.

[0038] The beneficial effects of the above technical solution are: the length of the waist-shaped hole 501 is less than the axial length of the truncated cone section 506 to prevent over-travel. The free length of the linear spring 6 is greater than the depth of the lower blind hole 402, so that the effective elastic force is always maintained.

[0039] In other embodiments of the present invention, the axial length of the frustum section 506 is one third to one half of the axial length of the upper cylindrical section 504 .

[0040] Figure 6 The travel distance is 1.00mm.

[0041] The beneficial effects of adopting the above technical solution are: the axial length of the frustum section 506 is set to a small half of the axial length of the upper cylindrical section 504, optimizing the effective working area of ​​the cone surface and balancing positioning accuracy and structural strength.

[0042] In one embodiment, the frustum section 506 is designed as a multi-stepped conical surface. Specifically, the frustum section 506 is divided axially into two or three sub-conical sections with varying angles, for example: an upper section with a 6° angle, a middle section with a 10° angle, and a lower section with a 14° angle. Furthermore, each sub-conical section is transitioned with a slightly rounded corner with a radius R of 0.5 mm. Furthermore, a cooling channel is incorporated into the movable insert 5. The channel inlet is located at the bottom of the process thread hole 502, and the outlet is located on the sidewall of the lower cylindrical section 507.

[0043] The multi-stage tapered surface creates a progressive compensation mechanism. The upper section's smaller taper angle accommodates precision bushing 1, while the lower section's larger taper angle is compatible with coarse-tolerance bushing 1. This improves compatibility compared to the original single-angle structure. Furthermore, the service life of the frustum section 506 is extended because the micro-radius transition disperses stress concentrations on the multi-stage tapered surface.

[0044] The design of the cooling channel can, to some extent, eliminate the effects of thermal deformation. During injection molding, the heat of the molten plastic is transferred through the bushing 1 to the movable insert 5. Constant-temperature oil is passed through the cooling channel to control the insert's operating temperature within a certain range, avoiding the positioning drift caused by thermal expansion in traditional structures.

[0045] like Figure 6 As shown, in some other embodiments of the present invention, the end of the positioning column 4 away from the limiting hole has an integral radially enlarged base 403.

[0046] The beneficial effects of adopting the above technical solution are: the base 403 integrally formed at the bottom end of the positioning column 4 enhances the installation stability, resists the impact force of injection molding, and prevents overall displacement.

[0047] In addition, in terms of material hardness, the hardness of the movable insert 5 is greater than the hardness of the positioning column 4 .

[0048] The present application also provides a mold, comprising the above low-cost insert structure for improving bushing tolerance.

[0049] The mold is an injection mold, and a low-cost insert structure that improves the bushing tolerance is used to temporarily fix the bushing 1. Molten plastic is injected into the injection mold and wraps the side of the bushing 1, that is, the circumferential surface, and is finally ejected from the mold after solidification.

[0050] The beneficial effect of adopting the above technical solution is: using the mold of the insert structure of the present application, the high-precision positioning capability of the bushing 1 is directly obtained, and it is compatible with bushings 1 with larger tolerances to reduce the production cost of composite injection molded parts.

[0051] like Figure 8 As shown, Figure 8 The lower pressure column 8 represents the front mold pressing the bushing after the mold is closed. Figure 8 The dotted line in the figure represents a movable insert, and a bushing 1 is provided on the top of the movable insert.

[0052] like Figure 9 and Figure 10 The bushing 1 shown includes an axial cavity 101 extending axially through the bushing. Depending on the radial thickness of the bushing 1, the bushing 1 also includes circumferential ribs 102 and circumferential grooves 103. A circumferential groove 103 is formed between two circumferential ribs 102. Molten plastic also enters the circumferential groove. The two circumferential ribs 102 and one circumferential groove 103 of the bushing 1 have equal axial lengths.

[0053] like Figure 8 As shown, the difference between the radius of the positioning cylinder 4 and the radius of the movable insert 5 is greater than the radial thickness of the bushing 1.

[0054] like Figures 1 to 4 The figure shows an embodiment before improvement, namely, the improved positioning post 2. The bushing is placed on the positioning post with a diameter of 5.59 mm in the mold, and then the front mold is pressed down to close the mold. At this time, if the inner diameter tolerance of the bushing is Φ5.60 (+0.04 / 0), the maximum offset of the center of the bushing relative to the center of the positioning post is 0.025 mm. The position of the bushing after molding can meet the product requirements, but there are higher requirements for the inner diameter tolerance of the bushing, which leads to an increase in the purchase price of the bushing. If a bushing with an inner diameter tolerance of Φ5.60 (+0.08 / 0) is selected to reduce the purchase price of the bushing, then the maximum offset of the center of the bushing relative to the center of the positioning post is 0.045 mm, and the position of the bushing after molding may not meet the accuracy requirements of the bushing position on the product.

[0055] The bushing is positioned using a 5.59mm diameter positioning column, which has a simple and reliable structure. The disadvantage is that the bushing inner diameter is required to be high, which leads to an increase in cost.

[0056] like Figures 5 to 10 This is an improved embodiment, namely, the improved movable positioning column 3 of the present application. The bushing is placed on the movable insert of the positioning column, and the front mold is pressed down to close the mold to form. At this time, since the movable insert has an inclined surface and upper and lower movable bushings, the position of the bushing can be automatically corrected with the positioning column. Therefore, the offset of the bushing center relative to the center of the movable insert is 0mm, and the positioning accuracy is better. At this time, the position of the bushing after molding can also meet the product requirements. However, the requirement for the inner diameter tolerance of the bushing does not need to be very high, and can be enlarged to Φ5.60 (+0.08 / 0), thereby reducing the purchase price of the bushing and making the product more accurate.

[0057] The principle is to use a movable insert with an inclined surface and up and down movement. When the front mold is pressed down, the bushing can automatically correct the position of the positioning column, thereby achieving centering positioning.

[0058] The advantages are higher positioning accuracy and lower tolerance requirements on the inner diameter of the bushing, thereby reducing production costs.

[0059] Figure 11 The inner diameter tolerance of the bushing is Φ5.60 (+0.04 / 0), Figure 11 It is the bushing that needs to be used before improvement. Figure 12 The bushing 1 that can be selected after the improvement of the present invention has an inner diameter tolerance of Φ5.60 (+0.08 / 0). Figure 12 The inner diameter fluctuation range of the bushing 1 can be larger, and the requirement for the inner diameter dimensional accuracy of the bushing 1 is not so high.

[0060] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low-cost insert structure for improving bushing tolerance, characterized in that: include: Positioning column with a limiting hole on the top; A movable insert is movably assembled with the limiting hole, the movable insert having elastic potential energy in a depth direction away from the limiting hole, and an upper portion of the movable insert is exposed from the limiting hole; Wherein, along the depth direction of the limiting hole, the movable insert has an upper cylindrical section, a frustum section, and a lower cylindrical section in sequence, the outer diameter of the upper cylindrical section is smaller than the outer diameter of the lower cylindrical section, and the outer diameter of the frustum section gradually increases; The outer wall at the junction of the truncated cone section and the upper cylindrical section is transitioned through an inner fillet; The axial end edge of the upper cylindrical section away from the truncated cone section has an outer rounded corner; When the movable insert is located at the extreme position away 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.

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

4. The low-cost insert structure for improving bushing tolerance according to claim 1, characterized in that: A process tooth hole is recessed at one axial end of the movable insert, the axis of the process tooth hole coincides with the axis of the movable insert, and the axial length of the process tooth hole is greater than the sum of the axial lengths of the upper cylindrical section and the truncated cone section.

5. The low-cost insert structure for improving bushing tolerance according to claim 1, characterized in that: 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.

6. The low-cost insert structure for improving bushing tolerance according to claim 5, characterized in that: The movable insert has a waist-shaped hole in the lower cylindrical section, the length direction of the waist-shaped 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, and the limiting pin is located in the waist-shaped hole.

7. The low-cost insert structure for improving bushing tolerance according to claim 6, characterized in that: The distance between the two centers of the waist-shaped hole is smaller than the axial length of the truncated cone segment; the axial length of the compression spring in an uncompressed state is greater than the axial length of the lower blind hole.

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

9. The low-cost insert structure for improving bushing tolerance according to claim 1, characterized in that: The end of the positioning column away from the limiting hole is provided with an integral radially expanded base.

10. A mold, characterized in that: An insert structure comprising the low-cost bushing tolerance improvement according to any one of claims 1 to 9.

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