A screw cold heading one-step forming die

Abstract

The utility model provides a kind of screw cold upsetting one-time forming die, to solve the problems of low production efficiency and poor quality of existing screw cold upsetting die, including upper die and lower die, upper die and lower die coaxial arrangement, upper die is equipped with cylindrical pre-pore, upper die kernel and plum blossom punch needle, lower die is equipped with lower die kernel, include flange step cavity and stem forming cavity, and be equipped with ejector pin;The utility model is through die integration structure design, realize the one-time cold upsetting forming of screw head, flange and stem, avoid multi-station transfer, significantly improve production efficiency, at the same time, the setting of transition curved surface and outer expansion corner structure makes screw corner clear, shape stable, improve finished product quality, applicable to the efficient continuous production of high-strength screw, with good industrial application prospect.

Description

Technical Field

[0001] This utility model relates to the field of screw mold technology, and in particular to a screw cold heading one-time forming mold. Background Technology

[0002] Screw cold heading forming dies are a specialized mold system that uses plastic deformation to shape metal wire or bar stock into screw heads in one step or gradually at room temperature. They are usually installed on cold heading machines or heading machines and are the core tools for mass production of screws, bolts and other fasteners. Existing screw dies on the market are formed by stacking multiple forming dies in sequence. Each forming die has a core with forming holes. The forming holes in each forming die are connected in sequence to cold head screws of various shapes.

[0003] Currently, many cold heading dies for screws cannot be formed in one step, such as Figure 1 and Figure 2 As shown, after the existing mold cold-forgings the screw blank, it is necessary to use other processing equipment to further process the screw in order to complete the manufacturing of the entire screw. This is time-consuming, labor-intensive, and wasteful of resources, while also reducing production efficiency. In addition, during the stamping of the screw, the shape of the stamped screw may be deformed due to the unstable internal structure of the mold, resulting in poor quality of the finished screw.

[0004] The utility model patent with authorization announcement number CN211915367U discloses a "cold heading forming mold for screws", which includes multiple forming molds stacked sequentially. The feature is that each of the two adjacent forming molds has a groove and a platform that can cooperate with each other. The inner sidewall of the groove and the outer sidewall of the platform are inclined. The two adjacent forming molds are stacked by mutual support through the inner sidewall of the groove and the outer sidewall of the platform. This utility model improves the stability of the stacking between adjacent forming molds, thereby improving the quality of cold heading forming of screws. However, the process of this utility model is scattered and requires multiple workstations to complete. The operation is complicated. Screws need to be transferred between different molds for processing, which greatly slows down the production rhythm. The line changeover and debugging are time-consuming and the overall production efficiency is low.

[0005] In summary, existing cold heading dies for screws typically have the following drawbacks: 1) Low production efficiency: Some existing screw cold heading molds have dispersed processes that require multiple workstations to complete, making the operation complex. Screws need to be transferred between different molds for processing, which significantly slows down the production pace. The time-consuming process of changing lines and debugging makes it difficult to improve overall efficiency. 2) Poor finished product quality: Some existing cold heading molds for screws have low geometric accuracy, high resistance to filling with internal hexagonal or vertical teeth, and obvious tooth tip radius after cold heading, which cannot meet the requirements for high-strength connection; the gap between the ejector pin and the cavity is too large, which easily leads to the superposition of positioning errors, resulting in insufficient coaxiality and corner filling, and the geometric accuracy and finished product quality are difficult to meet the requirements of fasteners. Summary of the Invention

[0006] The purpose of this invention is to solve the problems in the prior art by proposing a one-time cold heading mold for screws, which can solve the problems of low production efficiency and poor product quality.

[0007] To achieve the above objectives, this utility model proposes a one-time cold heading mold for screws, comprising an upper mold and a lower mold, characterized in that: the upper mold and the lower mold are coaxially arranged opposite each other; the upper mold includes a cylindrical pre-hole and an upper mold core arranged sequentially from top to bottom; the lower end of the cylindrical pre-hole is connected to the upper end of the upper mold core; a plum blossom punch is fixedly provided at the top of the upper mold core; and a screw head forming cavity is provided at the bottom of the upper mold core; the lower mold has a lower mold core, which has a flange step cavity and a rod forming cavity connected sequentially; the lower end of the lower mold core has a screw ejection port communicating with the rod forming cavity; and a slidable ejector pin is provided in the screw ejection port.

[0008] Preferably, the plum blossom punch is located at the upper end of the forming cavity of the screw head, and the shank of the plum blossom punch extends upward and is fixed in the cylindrical pre-hole.

[0009] Preferably, the opening of the screw head forming cavity is provided with a transition surface and an outwardly expanding angular structure. The transition surface is recessed from the inner wall of the screw head forming cavity toward the central axis, and the outwardly expanding angular structure surrounds and connects to the outer edge of the transition surface. The transition surface and the outwardly expanding angular structure form the closed opening contour of the screw head forming cavity.

[0010] Preferably, the upper end of the flange step cavity opens onto the upper end face of the lower mold core, and the flange step cavity, the rod forming cavity, and the screw head forming cavity are coaxially matched.

[0011] Preferably, the cross-sectional diameter of the flange step cavity is larger than the cross-sectional diameter of the screw head forming cavity.

[0012] Preferably, the outer diameter of the ejector pin matches the lower section diameter of the rod forming cavity, and the upper end face of the ejector pin extends into the lower end of the rod forming cavity.

[0013] The beneficial effects of this utility model are: 1) Improved production efficiency: By using a one-time forming mold for cold heading of screws, the multiple processes that originally required transfer between different molds are compressed into a one-time forming mold. The screws do not need to be moved from feeding to the finished product ejection, the machine setup time is greatly shortened, the productivity is increased, and efficient continuous production is achieved. 2) Simplified operation process: With the built-in guiding function of the coaxial continuous cavity, the cylindrical pre-hole is first used to center the screw, and the plum blossom punch is fixed to the head forming cavity as a whole. There is no need for manual slotting, repeated slotting or adjustment of the punch position. The debugging process is simplified, which greatly reduces the skill threshold and daily debugging workload. 3) Improved finished product quality: The transition curved surface and outward-expanding angular structure make the screw edges more distinct, the ejector pin and the rod forming cavity match and slide, the internal structure of the mold is stable, and the shape of the stamped screw meets the high-strength connection requirements of the screw, thus improving the quality of the finished product.

[0014] The features and advantages of this utility model will be described in detail through embodiments and accompanying drawings. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the upper mold section of an existing mold; Figure 2 Yes, yes Figure 1 A schematic diagram of the manufactured screw; Figure 3 This is a schematic diagram of the structure of this utility model; Figure 4 This is a schematic diagram of the production process of this utility model; Figure 5 yes Figure 3 A schematic diagram of the upper mold cross-section; Figure 6 This is a schematic diagram of the screw manufactured according to this utility model.

[0016] Numbering in the diagram: 1-Upper mold; 2-Lower mold; 3-Upper mold core; 31-Cylindrical pre-hole; 32-Screw head forming cavity; 33-Plum punch; 34-Outwardly expanding angular structure; 35-Transition curved surface; 4-Lower mold core; 41-Flange step cavity; 42-Rod forming cavity; 5-Screw ejection port; 51-Ejector pin; 6-Screw. Detailed Implementation

[0017] Example 1: See Figures 3 to 6 This utility model discloses a one-time cold heading mold for screws, comprising an upper mold 1 and a lower mold 2, characterized in that: the upper mold 1 and the lower mold 2 are coaxially arranged opposite each other, such as... Figure 3 and Figure 4As shown, the upper mold 1 includes a cylindrical pre-hole 31 and an upper mold core 3 arranged sequentially from top to bottom. The lower end of the cylindrical pre-hole 31 is connected to the upper end of the upper mold core 3. A plum blossom punch 33 is fixedly provided on the top of the upper mold core 3, and a screw head forming cavity 32 is provided on the bottom of the upper mold core 3. The lower mold 2 is provided with a lower mold core 4. The lower mold core 4 is provided with a flange step cavity 41 and a rod forming cavity 42 connected sequentially. The lower end of the lower mold core 4 is provided with a screw ejection port 5 that communicates with the rod forming cavity 42. A slidable ejector pin 51 is provided in the screw ejection port 5.

[0018] like Figure 5 and Figure 6 As shown, the plum blossom punch 33 is located at the upper end of the screw head forming cavity 32, and the shank of the plum blossom punch 33 extends upward and is fixed in the cylindrical pre-hole 31; the opening of the screw head forming cavity 32 is provided with a transition surface 35 and an outwardly expanding angular structure 34. The transition surface 35 is recessed from the inner wall of the screw head forming cavity 32 toward the central axis, and the outwardly expanding angular structure 34 surrounds and connects to the outer edge of the transition surface 35. The transition surface 35 and the outwardly expanding angular structure 34 form the closed opening contour of the screw head forming cavity 32; the upper end of the flange step cavity 41 opens at the upper end face of the lower mold core 4, and the flange step cavity 41, the rod forming cavity 42 and the screw head forming cavity 32 are coaxially matched; the cross-sectional diameter of the flange step cavity 41 is larger than the cross-sectional diameter of the screw head forming cavity 32; the outer diameter of the ejector pin 51 matches the lower section hole diameter of the rod forming cavity 42, and the upper end face of the ejector pin 51 extends into the lower end of the rod forming cavity 42.

[0019] In this embodiment, the plum blossom punch 33 in the upper mold 1 adopts a six-petal circular arched profile, and the opening of the screw head forming cavity 32 of the upper mold core 3 is a continuous single circular arc transition surface 35 and a conical outward expansion angular structure 34; the inner wall of the flange step cavity 41 of the lower mold core 4 remains a smooth straight cylinder, and the upper mold core 3 and the lower mold core are made of hard alloy material.

[0020] Example 2: This embodiment is basically the same as embodiment 1, except that: an annular cooling channel is added to the bottom of the flange step cavity 41 of the lower mold core 4, and circulating cooling oil is circulated in the annular cooling channel; a micro spring buffer cavity is added to the center of the ejector pin 51, so that the end of the ejector pin decelerates before contacting the flange. The new structure effectively reduces the temperature rise at the root of the flange, reduces thermal adhesion wear, and at the same time buffers the impact and eliminates ejection marks.

[0021] In this embodiment, Example

[0022] This embodiment is basically the same as embodiment 1, except that the transition surface 35 is changed to an inward concave arc surface and the outward expanding corner structure 34 is changed to a combination of straight and inclined surfaces. The screw is first concentrated by the inward concave arc and then flows outward along the straight and inclined surface, easily filling the tooth top. This makes the plum blossom corners clear, the surface smooth, and the forming load reduced.

[0023] Working principle: Work steps: After the upper mold 1 and the lower mold 2 are closed coaxially, the blank is inserted into the cylindrical pre-hole 31 and enters the upper mold core 3. The upper mold 1 is pressed down, the plum blossom punch 33 is positioned and pre-punched into the plum blossom groove. The head of the blank is constrained by the transition curved surface 35 and the outward expansion angular structure 34 in the screw head forming cavity 32 to complete the head and chamfer forming. At the same time, the blank flows down into the flange step cavity 41 to form a flange, and enters the rod forming cavity 42 to form a smooth rod. Then the upper mold moves up, and the ejector pin 51 pushes the finished screw out of the rod forming cavity along the screw ejection port 5 to achieve one-time cold heading forming.

[0024] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the protection scope of the present invention.

Claims

1. A cold heading die for screws, comprising an upper die (1) and a lower die (2), characterized in that: The upper mold (1) and the lower mold (2) are coaxially opposite each other. The upper mold (1) includes a cylindrical pre-hole (31) and an upper mold core (3) arranged sequentially from top to bottom. The lower end of the cylindrical pre-hole (31) is connected to the upper end of the upper mold core (3). The top of the upper mold core (3) is fixedly provided with a plum blossom punch (33). The bottom of the upper mold core (3) is provided with a screw head forming cavity (32). The lower mold (2) is provided with a lower mold core (4). The lower mold core (4) is provided with a flange step cavity (41) and a rod forming cavity (42) connected sequentially. The lower end of the lower mold core (4) is provided with a screw ejection port (5) connected to the rod forming cavity (42). The screw ejection port (5) is provided with a sliding ejector pin (51).

2. The screw cold heading one-time forming mold as described in claim 1, characterized in that: The plum blossom punch (33) is located at the upper end of the screw head forming cavity (32), and the shank of the plum blossom punch (33) extends upward and is fixed in the cylindrical pre-hole (31).

3. The screw cold heading one-time forming mold as described in claim 1, characterized in that: The opening of the screw head forming cavity (32) is provided with a transition surface (35) and an outwardly expanding angular structure (34). The transition surface (35) is recessed from the inner wall of the screw head forming cavity (32) toward the central axis. The outwardly expanding angular structure (34) surrounds and connects to the outer edge of the transition surface (35). The transition surface (35) and the outwardly expanding angular structure (34) constitute the closed opening contour of the screw head forming cavity (32).

4. The screw cold heading one-time forming mold as described in claim 1, characterized in that: The upper end of the flange step cavity (41) opens onto the upper end face of the lower mold core (4), and the flange step cavity (41), the rod forming cavity (42), and the screw head forming cavity (32) are coaxially matched.

5. The screw cold heading one-time forming mold as described in claim 1, characterized in that: The cross-sectional diameter of the flange step cavity (41) is larger than the cross-sectional diameter of the screw head forming cavity (32).

6. The screw cold heading one-time forming mold as described in claim 1, characterized in that: The outer diameter of the ejector pin (51) matches the lower section diameter of the rod forming cavity (42), and the upper end face of the ejector pin (51) extends into the lower end of the rod forming cavity (42).

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