A bolt bushing press-fit assembly mold

Abstract

This invention discloses a bolt bushing press-fit assembly mold, relating to the field of press-fit mold technology. It includes an upper mold and a lower mold. A centrally located placement groove is formed at the upper end of the lower mold, and a sleeve is installed within the groove. A press-fit plate is positioned on the upper end face of the lower mold via the sleeve. The lower end face of the upper mold has a forming conical surface for axially pressing the sleeve. A resettable, axially movable movable ring is fitted onto the outer diameter surface of the lower mold. In the unpressurized state, the upper end face of the movable ring extends beyond the upper end face of the lower mold. When the upper mold moves downward, the forming conical surface of the upper mold abuts against the end of the sleeve, causing the upper end of the sleeve to receive radially outward pressure. The sleeve flows upward, forming a protrusion. With continued pressing, the press-fit plate flattens against the lower mold. This bolt bushing press-fit assembly mold allows the sleeve and the hole wall of the press-fit plate to move axially during pressing, and the flattening of the protrusion effectively avoids the formation of steps, resulting in a greater pushing force and more stable press-fitting.

Description

Technical Field

[0001] This invention relates to the field of riveting mold technology, specifically to a bolt bushing riveting assembly mold. Background Technology

[0002] Press riveting is a process that uses plastic deformation to permanently fix fasteners such as bolts, nuts, and bushings into pre-drilled holes in thin plates. Among them, bolt bushing assemblies are widely used in applications that require withstanding large pull-out forces and torques because they provide both high-strength internal threads and a long support surface.

[0003] Currently, the standard press-fit process in the industry is as follows: First, a pre-drilled hole is machined in the thin plate; then, the bolt bushing is placed into the pre-drilled hole, so that its flange face fits against the plate surface; finally, using a special press-fit die, a huge axial pressure is applied to the protruding part of the bushing (i.e., the riveting section). Under the action of pressure, the material of the bushing's riveting section undergoes plastic flow, expands radially and tightly fills the pre-drilled hole, while some material extends to the back of the plate, forming a "stuck head" structure, thereby achieving mechanical interlocking.

[0004] The traditional press-fit riveting process described above has certain drawbacks. During the riveting process, the flow rate and shape of the bushing's riveting section extending towards the back of the sheet metal cannot be precisely controlled. When the flow rate is small, a step forms between the bushing end and the sheet metal, significantly reducing the reverse bearing area required to resist the bushing's ejection. Consequently, the maximum static friction and mechanical locking force provided are also correspondingly lower. Conversely, when the flow rate is large, the bushing end forms a junction with the upper surface of the sheet metal contact surface. At this junction, the bushing is subjected to extreme compression, resulting in edge burrs (sharp edges), which are detrimental to subsequent assembly, especially during manual assembly, and can easily cause injury to the operator. Therefore, we propose a bolt bushing press-fit assembly mold. Summary of the Invention

[0005] The purpose of this invention is to provide a bolt bushing press-fit assembly mold to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a bolt bushing press-fit assembly mold, comprising an upper mold and a lower mold, the upper mold and the lower mold being coaxially arranged and moving towards each other. A placement groove located at the center of the upper end of the lower mold is opened, and a sleeve is installed in the placement groove. The press-fit plate is positioned on the upper end face of the lower mold through the sleeve. The lower end face of the upper mold is provided with a forming conical surface for axially pressing the sleeve. A resettable movable ring that moves axially is fitted on the outer diameter surface of the lower mold. The movable ring is used to lift the press-fit plate. In the unpressurized state, the upper end face of the movable ring extends beyond the upper end face of the lower mold. When the upper mold moves downward, the forming conical surface of the upper mold abuts against the end of the sleeve, so that the upper end of the sleeve receives radially outward pressure. The sleeve flows upward to form a protrusion, and after continued pressing, the sleeve material presses outward against the wall of the press-fit plate hole. After the lower end face of the upper mold contacts the press-fit plate, the movable ring moves downward synchronously until the press-fit plate is flat with the lower mold.

[0007] Preferably, the contact end face between the upper die and the riveting plate is provided with a protrusion. The protrusion is located at the boundary between the upper end face of the sleeve and the riveting plate. After the upper die is fully pressed down, the protrusion forms a depression at the riveting point.

[0008] Preferably, the protruding cross section is arc-shaped, and the outer surface of the protrusion is provided with annular obstructions distributed radially to blunt the edge of the sleeve end face.

[0009] Preferably, the upper mold is provided with a groove facing the lower mold, and a cutting block is provided in the groove. The cutting block is pressed down a second time after the lower mold is fully pressed down to cut the edge of the upper end face of the sleeve.

[0010] Preferably, the inner surface of the cutting end of the blade is provided with an arc segment to blunt the cut edge.

[0011] Preferably, a limiting ring is integrally provided at the extended end of the forming cone surface of the upper mold, and the limiting ring restricts the radial inward flow range of the sleeve end.

[0012] Preferably, the radial width of the forming cone surface of the upper mold covers the upper end face of the sleeve.

[0013] Preferably, the movable ring is adjustablely mounted on the lower mold via bolts.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] The riveting die of the present invention can cause the sleeve and the hole wall of the riveting plate to move axially when pressed down, and the raised flattening can effectively avoid the formation of steps, thereby making the riveting push force greater and the riveting more stable.

[0016] The protrusion provided on the upper mold of the present invention can press down the gap between the sleeve and the riveting plate to form a recess, thereby preventing the burrs from being in a horizontal state and thus avoiding damage to the operator.

[0017] The upper mold of the present invention has a cutting block that cuts the sharp edge generated at the end of the sleeve, removes burrs, and at the same time, its arc segment can blunt the right-angle edge, that is, form an arc transition, and completely avoid the possibility of damage. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall riveting process of the present invention;

[0019] Figure 2 for Figure 1 Enlarged schematic diagram of the structure at point A in the middle;

[0020] Figure 3 for Figure 1 Enlarged schematic diagram of the structure at point B;

[0021] Figure 4 for Figure 1 Enlarged schematic diagram of the structure at point C;

[0022] Figure 5 This is a schematic diagram of the structure at the junction of the sleeve and the press-fit plate;

[0023] Figure 6 This is a schematic diagram showing the state of the cutting block in the upper die and during downward cutting;

[0024] Figure 7 This is a schematic diagram of a partial cross-sectional structure of the blade block;

[0025] Figure 8 This is a schematic diagram of the limiting ring structure.

[0026] In the diagram: 1-Upper mold; 101-Forming cone surface; 102-Protrusion; 103-Slide groove; 104-Limiting ring; 105-Stepped surface; 2-Lower mold; 201-Placement groove; 3-Sleeve; 301-Protrusion; 4-Riveting plate; 5-Moving ring; 6-Cutting block; 601-Circular arc segment; 7-Spring. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Please see Figure 1 , Figure 2 , Figure 3 and Figure 4This invention provides a technical solution: a bolt bushing press-fit assembly mold, comprising an upper mold 1 and a lower mold 2, both of which are shaft-shaped. The upper mold 1 is hollow, with a stepped surface 105 and a forming conical surface 101 on its lower end face. The stepped surface 105 is horizontal and fits against the upper surface of the press-fit plate 4 when pressed down. The forming conical surface 101 is located radially inside the stepped surface 105 and axially protrudes downward from the stepped surface 105. The forming conical surface 101 is inverted conical and acts on the upper end face of the sleeve 3. The lower mold 2 is coaxially arranged with the upper mold 1. The sleeve 3 is riveted to the moving part. A blind hole placement groove 201 is provided at the center of the upper end face of the lower die 2. The placement groove 201 is used for positioning and placing the sleeve 3. The inner diameter of the placement groove 201 is adapted to the outer diameter of the sleeve 3. The upper end of the sleeve 3 extends beyond the placement groove 201 of the lower die 2. The sleeve 3 is the main part of the bolt bushing. Its upper end has a step to support the riveting plate 4. The riveting plate 4 and the sleeve 3 are the two main parts of the riveting. A movable ring 5 is slidably provided on the outer diameter surface of the lower die 2. A spring 7 is also provided between the movable ring 5 and the lower die 2. The spring 7 is used to reset the sleeve.

[0029] Specifically, at least three sets of mounting holes are arranged in a circumferential array on the lower die 2. The mounting holes are connected to the movable ring 5 by bolts. The movable ring 5 can slide within the range limited by the axial bolts. One end of the spring 7 is set on the step of the lower die 2, and the other end acts on the movable ring 5. The bolt connection method can realize disassembly and adjustment to suit bushings with different riveting strokes.

[0030] The riveting process between the lower die 2 and the upper die 1 consists of four steps. First, the upper die 1 moves downwards, and in this state, the movable ring 5 supports the riveting plate 4, suspending it in mid-air. Second, the forming cone surface 101 of the upper die 1 abuts against the upper end face of the sleeve 3, pressing and riveting the sleeve downwards. During this process, the material at the upper end of the sleeve 3 flows in two directions: axially outwards, it tightly adheres to the hole wall of the riveting plate 4, while in the other direction it flows upwards, forming a protrusion 301. As the upper die 1... The continued downward pressure causes the sleeve 3 to press outward against the riveting plate 4, deforming the wall of the riveting plate 4 hole. This is the third step. In this step, the material at the end of the sleeve 3 flows downward. The fourth step is that the upper mold 1 continues to move downward, driving the riveting plate 4 and the movable ring 5 downward to compress the spring 7 until the riveting plate 4 is flat against the lower mold 2. During this process, the upper mold 1 presses the protrusion 301 back and shapes it flat. Here, the material of the sleeve 3 is tightly fitted with the riveting plate 4, and at the same time, the end face of the sleeve 3 is tightly fitted with the plane of the riveting plate 4.

[0031] See Figure 5 and 8The upper mold 1 has a protrusion 102 on the stepped surface. The cross-section of the protrusion 102 is preferably hemispherical and convex downwards. The radial width of the cross-section of the protrusion 102 covers the gap at the junction of the riveting plate 4 and the upper surface of the sleeve 3. That is, when the upper end of the sleeve 3 is pressed outwards along the axial direction, there is a dividing line between it and the riveting plate 4. At the upper end of this dividing line, the edge of the sleeve 3 will be pressed into a sharp shape and burrs will appear. Figure 5 At point N, by setting a protrusion 102, a local depression can be formed when the protrusion 102 is pressed down, so that the boundary line of the sleeve 3 and the rivet plate 4 is located in this depression, which can avoid burrs from causing damage to workers during manual assembly.

[0032] Furthermore, annular obstructions are arranged radially in sequence on the surface of the protrusion 102. These obstructions can be annular grooves or rough surfaces with high roughness, such as frosted surfaces. The grooves can obstruct the flow of material at the end of the sleeve 3 and prevent it from forming a sharp shape when extruded, thus creating passivation. Here, passivation means that the edge does not form a sharp angle and burrs are formed.

[0033] See Figure 6 The upper mold 1 has a downward-facing annular groove 103, and an annular blade 6 is set in the groove 103. The lower end face of the blade 6 is the cutting edge. Unlike the previous embodiment that produces a depression, in this embodiment, a non-indented local depression is formed by cutting off the sharp edge formed at the edge of the sleeve 3. The cross-sectional width of the groove 103 must also cover the maximum range of the boundary change between the sleeve 3 and the riveting plate 4, and the cutting edge is located at the minimum range value, so as to form an effective cut. Figure 6 The dotted line in the image represents the endpoint of the cutting edge's downward movement. During cutting, the waste material will shift laterally towards the cutting edge.

[0034] For further details, please refer to [link / reference]. Figure 7 The cross section of the blade 6 has a concave arc segment 601 on the inner diameter side of the cutting edge. The tip of the arc segment 601 is the cutting edge. The function of the arc segment 601 is to process the edge of the sleeve 3 after cutting, so that it is not a right angle and forms a non-sharp curved surface transition.

[0035] The cutting block 6 is pressed down after the upper mold 1 is fully pressed down. That is, the cutting block 6 can be an electrical component such as a cylinder or an equivalent driving structure. After the upper mold 1 is fully pressed down, the cutting block 6 is pressed down to cut. The outer diameter surface of the cutting block 6 is provided with a mating block that extends to the outside of the upper mold 1, thereby connecting and driving with the driving component. This part is an existing structure and component, so it will not be described in detail.

[0036] See Figure 3 and Figure 8 When the upper die 1 is pressed down, the end material of the sleeve 3 has a downward and radially inward movement process, that is... Figure 3As shown, the inner diameter surface of the sleeve 3 will protrude. This protrusion has an undefined shape, which leads to an uncertain amount of upward movement. Therefore, a limiting ring 104 is set to limit the radially inward position, so that it has a certain limiting state, thereby ensuring that the position of the junction between the sleeve 3 and the riveting plate 4 is relatively stable.

[0037] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A bolt bushing press-riveting assembly die, comprising an upper die (1) and a lower die (2), the upper die (1) and the lower die (2) are coaxially arranged and move towards each other, a central placement groove (201) is formed at an upper end of the lower die (2), a sleeve (3) is installed in the placement groove (201), a press-riveting plate (4) is positioned on an upper end face of the lower die (2) through the sleeve (3), and a forming taper face (101) for axially extruding the sleeve (3) is arranged on a lower end face of the upper die (1), characterized in that: The outer diameter surface of the lower die (2) is sleeved with a resettable movable ring (5) moving along the axial direction, which is used to lift the rivet plate (4). In the uncompressed state, the upper end surface of the movable ring (5) exceeds the upper end surface of the lower die (2). When the upper die (1) moves downward, the forming conical surface (101) of the upper die (1) contacts the end of the sleeve (3), so that the upper end of the sleeve (3) receives pressure along the radial direction outward. The sleeve (3) flows upward to form a protrusion (301), and after further extrusion, the sleeve (3) extrudes the rivet plate (4) hole wall outward. After the lower end surface of the upper die (1) contacts the rivet plate (4), the movable ring (5) is lowered synchronously until the rivet plate (4) is flat with the lower die (2); The contact end surface of the upper die (1) and the rivet plate (4) is provided with a protrusion (102), which is located at the boundary between the sleeve (3) and the upper end surface of the rivet plate (4). After the upper die (1) is completely pressed down, the protrusion (102) forms a recess at the rivet position. The cross section of the protrusion (102) is arc-shaped, and the outer surface of the protrusion (102) is provided with an annular barrier distributed along the radial direction, so as to blunt the edge of the sleeve (3) end surface; Or The upper die (1) is provided with a sliding groove (103) facing the lower die (2), and a cutter block (6) is arranged in the sliding groove (103). The cutter block (6) is pressed down again after the lower die (2) is completely pressed down, so as to cut the edge of the upper end surface of the sleeve (3). The cross section of the cutting end of the cutter block (6) is provided with a circular segment (601) on the inner surface side, so as to blunt the cutting edge.

2. A die for press-riveting a bolt bushing assembly according to claim 1, characterized in that: A limiting ring (104) is integrally arranged at the extension end of the forming conical surface (101) of the upper die (1), which limits the flow range of the sleeve (3) end along the radial direction inward.

3. A die for press-riveting a bolt bushing assembly as defined in claim 1, wherein: The radial width of the forming conical surface (101) of the upper die (1) covers the upper end surface of the sleeve (3).

4. The die assembly for press-riveting a bolt bushing according to claim 1, wherein: The movable ring (5) is adjustably arranged on the lower die (2) by bolts.

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