An automated continuous one-shot multi-part roll forming die

Abstract

The present application relates to the technical field of the round mould, specifically to an automatic continuous one-time multi-piece round mould, comprising a mould frame, an open-close movable mould and a movable mould, wherein the movable mould and the movable mould are combined to form a round cavity in the closed mould state, which is used for forming the shaft sleeve part of a workpiece; a core rod is arranged in the round cavity, wherein the core rod is composed of a straight shaping section and an expansion shaping section; the round cavity and the straight shaping section of the core rod jointly define the wall thickness and roundness of the main body section of the shaft sleeve part; the expansion shaping section only corresponds to the tail end local area in the circumferential direction of the shaft sleeve part; in the round process, the radial plastic expansion of the tail end of the round is forced by the radial protrusion, so that the outer surface of the tail end local area of the workpiece B is plastically deformed and extended to fill the area E, forming a self-locking, inhibiting the rebound of the free end of the round, and improving the round quality.

Description

Technical Field

[0001] This invention relates to the technical field of rolling dies, specifically to an automated continuous multi-piece rolling die. Background Technology

[0002] Rolling is a forming method that uses stamping dies to bend flat metal sheets into cylindrical or arc-shaped structures. It is widely used in the manufacturing of components such as hinges, bushings, and bushings. Especially in the fields of server cabinets and industrial control cabinets, the bushing part of hinges is almost entirely made by rolling.

[0003] In existing technologies, for precision rolled parts, especially thin-walled bushings, after the thin plate is rolled, the free edge at the circumference end lacks constraint and the springback is much greater than other parts, resulting in a "teardrop" shape with one end round and the other end pointed. This leaves a nearly tangent micro-plane at the inner hole joint, which damages the roundness of the bushing's inner hole, reduces the effective contact arc length with the pin, affects the smoothness of rotation, and increases wear. Summary of the Invention

[0004] This invention provides an automated continuous multi-piece rolling die. When the mandrel moves along its axial direction, the radial convexity acts on a local area at the tail end of the bushing, forcing the material at that location to undergo radial plastic expansion. This causes the outer surface of the local area at the tail end of workpiece B to undergo plastic deformation and extend to the filling area E, forming a self-locking mechanism. This suppresses the springback of the free end of the rolling process and improves the rolling quality.

[0005] To achieve the above objectives, the present invention provides the following technical solution: An automated continuous multi-piece rolling die includes: A mold base; a movable mold and a moving mold that open and close relative to each other; the movable mold and the moving mold, when closed, combine to form a rolled cavity for molding the bushing portion of the workpiece; a mandrel disposed inside the rolled cavity, the mandrel being composed of a straight forming section and an expansion forming section; the rolled cavity and the straight forming section on the mandrel together define the wall thickness and roundness of the main body section of the bushing portion; the expansion forming section corresponds only to the tail end local area in the circumferential direction of the bushing portion; the mandrel is configured to be able to move relative to the bushing portion, so that the expansion forming section forces the tail end local area to undergo radial plastic expansion, until the outer surface of the tail end local area forms an interference fit with the straight section of the workpiece's sheet, constituting a shape self-locking mechanism that suppresses springback.

[0006] Optionally, the expansion and shaping portion is a radial protrusion partially provided along the circumferential direction of the mandrel, and the circumferential width of the radial protrusion only covers the area where the joint of the bushing portion is located.

[0007] Optionally, the radial protrusion has a gradually thickening wedge-shaped cross section along the axial direction, with a smooth transition surface on the side facing the straight forming section, so as to guide the gradual plastic deformation of the local area at the tail end of the workpiece.

[0008] Optionally, the mandrel is configured to rotate about its axis, and the outer surface of the flattened section is designed with microtextures, which are dot matrix or cross mesh patterns formed by precision knurling.

[0009] Optionally, the mandrel has an oil leakage slit, which is parallel to the axis of the mandrel and located at the front end of the radial protrusion stroke. The mandrel is designed with an oil reservoir that supplies lubricating oil to the oil leakage slit, and the oil reservoir can be associated with an external oil pump module.

[0010] Optionally, the moving mold and the forming surface on the moving mold that constitutes the rolled cavity have at least one arc profile with a central angle greater than 180 degrees, so that during the mold closing process, the forming surface applies plastic bending to the end of the workpiece sheet exceeding the target bending angle to compensate for the initial springback after mold opening.

[0011] Optionally, it also includes an inner support ring, which is designed in a rolled cavity C. The outer wall of the inner support ring is slidably assembled with the inner wall of the rolled cavity C, and the inner wall of the inner support ring is slidably engaged with the outer wall of the straight shaping section on the mandrel.

[0012] Optionally, a feed gap is provided between the moving mold and the mold base, the feed gap allowing one end of the workpiece to pass through, and the bottom of the moving mold in the working position is used to limit and lock the sheet portion of the workpiece.

[0013] This invention provides an automated continuous multi-piece rolling die, which has the following advantages compared to the prior art: 1. By specially setting an expansion and shaping part on the mandrel, when the mandrel moves along its axial direction, the expansion and shaping part only acts on a local area at the tail end of the bushing, forcing the material at that location to undergo radial plastic expansion. This causes the outer surface of the tail end, which was originally located above the straight segment of the sheet, to bulge outward and extend, filling the filling area E and forming a deformation part T. The deformation part T and the straight segment of the sheet thus form a fit or interference contact relationship. Once the contact is formed, the path of the tail end to rebound outward is physically blocked by the straight segment of the sheet, and the elastic recovery force cannot open the joint, thereby forming a stable and reliable shape self-locking, effectively eliminating the teardrop shape and tangential straight edge defects of the free end after rolling.

[0014] 2. An arc profile with a central angle greater than 180 degrees is set on the forming surface of the rolled cavity formed by the moving mold and the fixed mold. During the mold closing process, the profile forces the end of the sheet metal to generate plastic bending exceeding the target bending angle around the straight forming section of the mandrel. After the mold is opened and unloaded, the elastic recovery of the material is just offset by the over-bending amount applied during mold closing. The bushing springs back to a closed state close to a perfect circle in the free state. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the external three-dimensional structure of the rolling die in this invention; Figure 2 For the present invention Figure 1 The right view; Figure 3 For the present invention along Figure 2 A schematic diagram of the structure viewed in section AA; Figure 4 This is a schematic diagram of the structure of the rolled-up cavity C in this invention; Figure 5 For the present invention Figure 3 Enlarged view of the structure at point D; Figure 6 This is a schematic diagram of the assembly of the fixed mold and the moving mold in this invention; Figure 7 This is an assembly diagram of the inner support ring and the rolling die in this invention; Figure 8 This is a schematic diagram of the structure of the mandrel and radial protrusions in this invention; Figure 9 This is a schematic diagram of the radial protrusion and the rolled-up cavity C in this invention; Figure 10 This is a schematic diagram of the structure of workpiece B in a self-locking state in this invention.

[0016] In the diagram: 1. Mold frame; 2. Moving mold; 3. Fixed mold; 4. Mandrel; 5. Oil leakage seam; 6. Radial protrusion; 8. Inner support ring. Detailed Implementation

[0017] 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.

[0018] Please see Figures 1 to 10 This invention provides a technical solution: an automated continuous multi-piece rolling die, comprising: Mold frame 1; movable molds 2 and 3 that open and close relative to each other; when the molds are closed, the movable molds 2 and 3 combine to form a rolled cavity C for forming the bushing portion of workpiece B; a mandrel 4 disposed inside the rolled cavity C, the mandrel 4 being composed of a flat forming section and an expansion forming section; the rolled cavity C and the flat forming section on the mandrel 4 together define the wall thickness and roundness of the main body section of the bushing portion; the expansion forming section corresponds only to the tail end local area in the circumferential direction of the bushing portion; the mandrel 4 is configured to be able to move relative to the bushing portion, so that the expansion forming section forces the tail end local area to undergo radial plastic expansion, until the outer surface of the tail end local area forms an interference fit with the straight section S of the workpiece B, thus forming a shape self-locking mechanism to suppress springback.

[0019] For information that requires attention and understanding, please refer to [the relevant documents / references]. Figure 10 The straight segment S of the leaf is an inherent structure of the hinge workpiece itself. It naturally becomes an extension of the bushing after the rolling is completed, and it is tangent to the initial end of the rolling.

[0020] Please see Figure 5 A filling area E will be formed between the straight segment S of the blade, the workpiece B, and the mandrel 4.

[0021] In existing technologies, when metal sheets are bent, two types of deformation occur simultaneously within the cross-section: tensile plastic deformation on the outer side and compressive plastic deformation on the inner side. When the external load is unloaded, the elastic deformation remaining inside the material is released. The outer layer wants to shorten, and the inner layer wants to lengthen, resulting in springback. This is especially true at the free end or tail end, which is the last part of the bending process where the bending moment drops sharply. Therefore, after rolling, the springback at the free end of the bushing is more severe. In this solution, the straight segment S of the sheet acts as a rigid stop, effectively utilizing it, but it cannot be directly used... This solution utilizes an expansion and shaping section. After the rolling process is completed, a filling area E appears at the free end of the bushing. This area is located above the straight section S of the sheet. When the mandrel 4 moves along its axial direction, the expansion and shaping section forces the local area at the tail end to undergo radial plastic expansion. This causes the outer surface of the local area at the tail end of the workpiece B to undergo plastic deformation and extend to the filling area E. At this time, the deformation section T is either in contact with or in conflict with the straight section S of the sheet, or forms an interference fit. This interaction between the two creates a self-locking mechanism, suppressing the springback of the free end of the rolling process and improving the rolling quality.

[0022] In a preferred embodiment, the expansion and shaping part is a radial protrusion 6 partially provided along the circumference of the mandrel 4. The circumferential width of the radial protrusion 6 only covers the area where the joint of the bushing part is located. In the bushing part after rolling and forming, the joint is the area with the weakest structure and the strongest tendency to rebound on the entire circumference. The radial protrusion 6 can enter the filling area E. Since the protrusion only acts on the joint part, the required radial expansion is very small, which can make the outer surface of the area bulge to form an interference fit with the straight section of the sheet.

[0023] Furthermore, the radial protrusion 6 has a gradually thickening wedge-shaped cross-section along the axial direction, with a smooth transition surface on the side facing the straight forming section, to guide the gradual plastic deformation of the local area at the tail end of the workpiece B. Please refer to [link to relevant documentation]. Figure 8 In this embodiment, when the radial protrusion 6 enters the local area of ​​the tail end of the workpiece bushing, if its front end face will generate an impact load at the moment of contact with the workpiece, the radial protrusion 6 is restricted to a wedge shape. However, the wedge surface of the wedge shape is an arc surface design, and it can better enter the plastic deformation process through a smooth transition surface, thereby effectively avoiding crushing, cracking and surface damage at the tail end of the thin-walled workpiece, while reducing the impact wear of the protrusion itself.

[0024] Based on the radial protrusion 6 embodiment, the mandrel 4 is further configured to rotate around its axis. The outer surface of the flat forming section is designed with micro-textures, which are dot matrix or cross mesh patterns formed by precision knurling. In this embodiment, during the aforementioned rolling forming process, after the workpiece sheet is bent into a cylindrical bushing part by the rolling cavity, its inner hole surface often has defects such as micro-waves, small protrusions, and inconsistent textures along the axial direction due to the uneven release of bending stress. Although these defects will not cause the workpiece to be scrapped, they will affect the fitting accuracy and rotation smoothness of the bushing inner hole and the pin. In this embodiment, the hardness of the micro-texture is higher than the hardness of the workpiece material. With the rotation of the mandrel 4 by an external driver, the micro-texture on the outer surface of the flat forming section and the inner wall of the bushing will generate circumferential relative movement. The increased friction of the mesh pattern can act on the inner wall of the rolled workpiece B, thereby completing the circumferential flattening and polishing of the inner wall of the bushing part.

[0025] Based on the embodiment of the radial protrusion 6, further, the mandrel 4 is provided with an oil leakage slit 5, which is parallel to the axis of the mandrel 4 and located at the front end of the radial protrusion 6's stroke. The mandrel 4 is designed with an oil reservoir that supplies lubricating oil to the oil leakage slit 5. The oil reservoir can be associated with an external oil pump module. In the aforementioned embodiment, the mandrel 4 needs to perform axial feed motion relative to the bushing during operation. During the process of the radial protrusion 6 contacting a local area at the tail end of the workpiece and forcing its radial plastic expansion, significant contact pressure and frictional heat are generated. Insufficient lubrication may lead to scratches or adhesive wear on the inner wall of the workpiece, and accumulation of metal chips at the front end of the radial protrusion 6, affecting the diameter expansion accuracy. Please refer to [link to previous text]. Figure 8In this embodiment, the axial position of the oil leak seam 5 is located at the front end of the radial protrusion 6's stroke. The oil leak seam 5 is positioned just before the radial protrusion 6 enters the local area at the tail end of the workpiece, so as to achieve pre-lubrication. The cross-section of the oil leak seam 5 can be rectangular, trapezoidal, or arc-shaped, the groove depth can be controlled between 0.3 and 1 mm, and the groove width is within 2 mm. The axial length of the oil leak seam 5 covers the front section of the entire stroke range of the radial protrusion 6 from the beginning of contact with the workpiece to the completion of the diameter expansion, ensuring that the lubricating oil has been pre-applied to the inner wall of the workpiece before the diameter expansion action occurs.

[0026] In a preferred embodiment, the forming surfaces of the moving molds 2 and 3 that constitute the rolled cavity C have at least one arc profile with a central angle greater than 180 degrees. This allows the forming surfaces to apply plastic bending exceeding the target bending angle to the end of the workpiece B sheet during mold closing, compensating for the initial springback after mold opening. In the rolling forming process, after the metal sheet is bent around the mandrel 4 into a cylindrical bushing, springback inevitably occurs due to the release of elastic deformation within the material. Springback causes the bushing's bending angle to decrease and the arc to open, making it unable to maintain an ideal closed cylindrical state. However, in this embodiment, by designing the central angle of the arc profile to be greater than 180 degrees, plastic bending exceeding the target bending angle is applied to the end of the workpiece sheet during mold closing, ensuring that the elastic recovery of the material after mold opening is exactly offset by the over-bending amount. The bushing then returns to a near-circular closed state in its free state, thereby improving the end opening, elliptical, and teardrop-shaped conditions that inevitably occur in conventional rolling processes at the source, and completing the initial springback suppression.

[0027] It is important to note that the transition between arc segments greater than 180 degrees and regular arc segments should be smooth, without sharp corners or abrupt changes in cross-section, to ensure smooth material flow and prevent stress concentration during the bending process.

[0028] In summary, the rolling die further includes an inner support ring 8, which is designed within the rolling cavity C. The outer wall of the inner support ring 8 slides against the inner wall of the rolling cavity C, and the inner wall of the inner support ring 8 slides against the outer wall of the straight forming section on the mandrel 4. Please refer to [link to relevant documentation]. Figure 7 In this embodiment, the inner support ring 8 is designed on the side away from the radial protrusion 6. During the operation of the aforementioned rolling die, when the radial protrusion 6 acts on the local area at the tail end of the bushing, it will generate a radially outward pushing force. Although the circumferential range of this pushing force is narrow and the diameter expansion is small, it is applied on one side and locally, which can easily cause misalignment or deformation. When the expansion and shaping part applies a radial expansion force to the local area at the tail end of the bushing, the inner support ring 8 simultaneously supports the inner side of the other end of the bushing. This can prevent the overall skewness of the bushing, the unexpected deformation of the far end port, and the destruction of cylindricity caused by local diameter expansion. It is especially suitable for the precision rolling of thin-walled bushing workpieces with a large length-to-diameter ratio and poor rigidity.

[0029] Furthermore, a feed gap is left between the moving mold 3 and the mold base 1, allowing one end of the workpiece B to pass through, and the bottom of the moving mold 3 in the working position is used to limit and lock the sheet portion of the workpiece B.

[0030] By utilizing the above-mentioned structures, when the mandrel 4 moves along its axial direction, the radial protrusion 6 acts on the local area at the tail end of the bushing, forcing the material at that location to undergo radial plastic expansion. This causes the outer surface of the local area at the tail end of the workpiece B to undergo plastic deformation and extend to the filling area E, forming a self-locking mechanism. This suppresses the springback of the free end of the roll and improves the rolling quality.

[0031] The standard parts used in this embodiment can be purchased directly from the market, and the non-standard structural parts described in the specification and drawings can also be processed without any doubt based on existing technical common sense. At the same time, the connection methods of each component adopt mature conventional methods in the existing technology, and the machinery, parts and equipment all adopt conventional models in the existing technology, so they will not be described in detail here.

[0032] 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. An automated continuous multi-piece rolling die, characterized in that: include: Mold frame (1); The relative opening and closing moving mold (2) and moving mold (3); When the moving mold (2) and the moving mold (3) are in the closed state, they combine to form a rolled cavity (C) for forming the bushing part of the workpiece (B); The mandrel (4) is disposed inside the rolled cavity (C), and the mandrel (4) is composed of a flat shaping section and an expansion shaping section; The rolled cavity (C) and the straight shaping section on the mandrel (4) together define the wall thickness and roundness of the main body section of the bushing. The expansion and shaping part corresponds only to the tail end local area in the circumferential direction of the bushing part; The mandrel (4) is configured to move relative to the bushing portion, causing the expansion and shaping portion to undergo radial plastic expansion in the tail end local area until the outer surface of the tail end local area forms an interference fit with the straight segment (S) of the workpiece (B), thereby constituting a shape self-locking mechanism that suppresses springback.

2. The automated continuous multi-piece rolling die according to claim 1, characterized in that: The expansion and shaping part is a radial protrusion (6) partially provided along the circumferential direction of the mandrel (4), and the circumferential width of the radial protrusion (6) only covers the area where the joint of the bushing part is located.

3. The automated continuous multi-piece rolling die according to claim 2, characterized in that: The radial protrusion (6) has a gradually thickening wedge-shaped cross section along the axial direction and a smooth transition surface on the side facing the straight forming section, so as to guide the local area of ​​the tail end of the workpiece (B) to undergo gradual plastic deformation.

4. The automated continuous multi-piece rolling die according to claim 3, characterized in that: The mandrel (4) is configured to rotate about its axis, and the outer surface of the straight shaping section is designed with microtexture, which is a dot matrix or cross mesh formed by precision knurling.

5. The automated continuous multi-piece rolling die according to claim 3, characterized in that: The mandrel (4) has an oil leakage slit (5) which is parallel to the axis of the mandrel (4) and is located at the front end of the radial protrusion (6) stroke. The mandrel (4) is designed with an oil storage tank that supplies lubricating oil to the oil leakage slit (5). The oil storage tank can be associated with an external oil pump module.

6. The automated continuous multi-piece rolling die according to claim 1, characterized in that: The forming surfaces of the moving mold (2) and the moving mold (3) that form the rolled cavity (C) have at least one arc profile with a central angle greater than 180 degrees, so that during the mold closing process, the forming surfaces apply plastic bending to the end of the workpiece (B) sheet material exceeding the target bending angle to compensate for the initial springback after mold opening.

7. The automated continuous multi-piece rolling die according to any one of claims 1-6, characterized in that: It also includes an inner support ring (8), which is designed in a rolled cavity C. The outer wall of the inner support ring (8) and the inner wall of the rolled cavity C form a sliding fit. The inner wall of the inner support ring (8) and the outer wall of the straight shaping section on the mandrel (4) slide together.

8. The automated continuous multi-piece rolling die according to claim 7, characterized in that: A feed gap is left between the moving mold (3) and the mold frame (1), the feed gap allows one end of the workpiece (B) to pass through, and the bottom of the moving mold (3) in the working position is used to limit and lock the sheet part of the workpiece (B).

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