A near net shape die for copper-chromium contact firewheel

Abstract

The application discloses a kind of copper-chromium contact wind fire wheel type near net shape forming die, including mould cavity support body, upper punch, lower punch and support core;Mould cavity support body has the mould cavity containing hole vertically through along its axis on it, and multiple arc mouth adaptation convex edges extending in vertical direction are equipped on the inner side wall of mould cavity containing hole;Upper punch lower end is provided with multiple upper punch matching grooves arranged spirally extending around its radial plane;Lower punch is provided with multiple lower punch matching grooves arranged spirally extending around its radial plane on it, and lower punch matching groove is vertically through in lower punch along vertical direction;The mould can realize the integrated near net shape forming of wind fire wheel type copper-chromium contact, and the cooperation structure of the arc mouth adaptation convex edge of mould cavity support body, the upper punch matching groove of upper punch and the lower punch matching groove of lower punch can directly form the continuous spiral groove structure of contact blank body periphery in pressing forming process, simultaneously, the knife edge groove structure of axial penetration is synchronously formed by the knife edge core rod of support core, and the forming of all external features can be completed by single pressing.

Description

Technical Field

[0001] This invention relates to the field of copper-chromium contact molding and manufacturing technology, specifically to a near-net-shape molding die for copper-chromium contact in the shape of a fire wheel. Background Technology

[0002] Copper-chromium contacts are the core conductive and breaking components of medium- and high-voltage vacuum electrical appliances such as vacuum circuit breakers and vacuum load switches. Their density, shape accuracy, and structural reliability directly determine the rated current carrying capacity, short-circuit breaking performance, and service life of the switchgear. Among them, the windmill-type copper-chromium contact with a continuous spiral groove on the outside and an axially penetrating knife-edge groove on the inside can effectively optimize the electric field distribution on the contact surface, improve heat dissipation efficiency, and break and extinguish arc capabilities, and its application demand in the field of high-voltage switches is increasing.

[0003] Currently, copper-chromium contacts are generally manufactured using powder metallurgy pressing molding technology. Traditional near-net-shape forming molds can only form contact blanks with simple rotary structures such as cylindrical and disc shapes. For complex copper-chromium contacts with a whirlpool-like structure, the industry usually adopts a process route of simple blank pressing molding followed by subsequent machining and grooving. That is, a cylindrical blank is first pressed out using a mold, and then spiral grooves and knife-edge grooves are processed by CNC milling, EDM, wire cutting and other processes. This process has several drawbacks: First, it results in low material utilization, as machining requires the removal of a large amount of copper-chromium alloy raw materials, leading to a waste of precious metal resources and increasing production costs. Second, it has a long production cycle, with multiple machining processes lengthening the production process and making it difficult to achieve efficient mass production. Third, it damages the performance of the finished product, as machining can disrupt the continuous and dense structure of the powder metallurgy billet, reducing the mechanical strength and electrical and thermal conductivity of the contacts. Furthermore, machining stress can easily cause defects such as billet deformation and cracking, increasing the scrap rate. Fourth, existing complex structure forming molds are not adaptable enough. Although some segmented female molds can form billets with side grooves, the parting surface is prone to producing burrs, which can easily scratch and damage the surface of the groove during demolding. Moreover, the mold assembly accuracy is low and the lifespan is short, making it impossible to guarantee the continuous forming accuracy of the spiral groove. At the same time, there is currently no mold that can simultaneously complete the integrated forming of the spiral shape and the through-cutting groove in a single pressing process, resulting in low process integration and difficulty in meeting the production requirements of near-net-shape forming. Summary of the Invention

[0004] The purpose of this invention is to provide a near-net-shape forming mold for copper-chromium contact pins in the shape of a whirlpool, which can complete the forming of all external features in a single pressing.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A near-net-shape forming mold for copper-chromium contact windmill type includes a mold cavity support, an upper punch, a lower punch, and a support core; The mold cavity support has a mold cavity receiving hole that runs vertically through its axis, and the inner wall of the mold cavity receiving hole is provided with multiple arc-shaped fitting protrusions that extend vertically. The lower end of the upper punch has multiple upper punch forming grooves that extend spirally around its radial plane; The lower punch has multiple lower punch forming grooves that extend spirally around its radial plane, and the lower punch forming grooves extend vertically through the lower punch. The supporting core includes a core connector and multiple vertically extending knife-edge mandrels fixed to the top of the core connector.

[0006] Preferably, from the same axial perspective, the spiral direction of the upper punch forming groove and the lower punch forming groove are consistent, and the cross-sectional shape and size of the upper punch and the lower punch are the same.

[0007] Explanation: This structural design ensures that when the upper and lower punches are aligned and closed within the mold cavity, the spiral trajectories of the upper and lower punch forming grooves are precisely aligned and smoothly connected. This guarantees that the spiral groove structure on the outer periphery of the formed copper-chromium contact blank will have a continuous axial transition without misalignment, steps, or other forming defects, thus ensuring the overall forming accuracy of the windmill shape. At the same time, the upper and lower punches use the same cross-sectional shape and dimensional parameters, allowing them to share machining tooling, reducing mold manufacturing costs, and improving component interchangeability, which facilitates daily mold maintenance and component replacement.

[0008] Preferably, the side opening formed between the upper punch forming groove and the outer side wall of the upper punch is chamfered, and the side opening formed between the lower punch forming groove and the outer side wall of the lower punch is chamfered. The upper punch slides down into the mold cavity receiving hole, and each arc-shaped fitting protrusion slides into the side opening of each upper punch fitting groove. The lower punch slides and fits into the mold cavity receiving hole from bottom to top, and each arc-shaped fitting protrusion slides and fits into the side opening of each lower punch fitting groove.

[0009] Explanation: The chamfering treatment of the side openings between the upper punch forming groove and the outer wall of the upper punch, and the chamfering treatment of the side openings between the lower punch forming groove and the outer wall of the lower punch, optimizes the contact state when the arc-shaped fitting protrusion slides with the corresponding forming groove, reduces the frictional resistance and local stress concentration of the mating surface, avoids problems such as tearing and jamming of the mating surface, improves the smoothness of the mold reciprocating motion, and effectively extends the service life of the mold. The one-to-one sliding fit structure between the arc-shaped fitting protrusion and the upper and lower punch forming grooves can simultaneously provide circumferential limiting and vertical motion guidance for the upper and lower punches, ensuring that the upper punch does not deflect circumferentially during the downward pressing process, ensuring that the spiral trajectory of the upper and lower punch forming grooves is always accurately aligned, and at the same time, it can constrain the coaxiality of the mold cavity support and the upper and lower punches, improve the sealing performance of the forming cavity, and prevent raw material powder from overflowing from the mating gap during the pressing process, thus preventing flash.

[0010] Preferably, the arc-shaped adapter protrusion extends into one side wall of the lower punch forming groove and forms a mandrel adapter through groove between the inner side wall of the lower punch forming groove; The cross-section of the blade mandrel is consistent with the cross-sectional shape and size of the mandrel adapter slot, and multiple blade mandrels slide and fit in the adapter slots from bottom to top.

[0011] Description: The mandrel adapter slot is formed by the arc-shaped adapter protrusion extending into the inner wall of the lower punch forming slot and enclosing it with the inner wall of the lower punch forming slot. This eliminates the need to separately machine the mandrel mounting hole on the lower punch, simplifying the lower punch's machining process. At the same time, the positioning reference of the arc-shaped adapter protrusion can be used to ensure the positional accuracy of the mandrel adapter slot. The cross-section of the cutting edge mandrel is consistent with the cross-sectional shape and size of the mandrel adapter slot and adopts a sliding fit. This provides precise guidance for the lifting and lowering movement of the supporting core, preventing the cutting edge mandrel from deflecting or bending, ensuring that the formed cutting edge slot structure is accurately positioned and has a smooth inner wall. It also allows the cutting edge mandrel to be smoothly pulled out of the blank during demolding, avoiding damage to the inner wall of the blank's slot and reducing the scrap rate during demolding.

[0012] Preferably, the upper punch is fixedly connected to the main cylinder of the press via the upper punch cover, and the mold cavity support is fixed in an annular female mold sleeve coaxial with it, and the female mold sleeve is fixed on the top cylinder of the press; The lower punch is fixedly connected to the die base of the press via the lower punch cover; The supporting core is fixedly installed on the top of a mandrel connecting rod by a core gland, and the mandrel connecting rod is fixedly connected to the central cylinder of the press.

[0013] Description: It can realize the reliable connection between the corresponding mold components and the press drive components, while facilitating the quick disassembly and replacement of mold components, improving the convenience of mold maintenance and repair. The independent drive control of each mold component provides hardware support for all processes such as material loading and positioning, floating pressing, and step demolding, perfectly adapting to the near-net-shape forming process requirements of the windmill-type copper-chromium contact.

[0014] Compared with the prior art, the beneficial effects of the present invention are reflected in the following aspects: 1. The present invention has a reasonable structural design, which can realize the one-piece near-net-shape forming of the windmill-shaped copper-chromium contact. Through the matching structure of the upper punch forming groove of the upper punch, the lower punch forming groove of the lower punch, and the arc-shaped fitting convex edge of the mold cavity support, the continuous spiral groove structure on the outer periphery of the contact blank can be directly formed during the pressing process. At the same time, the axial through-groove structure is formed simultaneously through the knife-edge mandrel of the supporting core. All external features can be formed in a single pressing. The size of the blank after forming is close to the finished product requirements. No need for a large number of subsequent machining processes, which greatly improves the utilization rate of copper-chromium materials, reduces precious metal processing losses, and avoids the destruction of the dense structure continuity of the blank by machining. It effectively ensures the mechanical properties and electrical and thermal conductivity of the copper-chromium contact. 2. This invention operates stably and reliably, exhibiting excellent molding accuracy and service life. The arc-shaped adapter ridge on the inner side of the mold cavity support body can simultaneously provide guidance and positioning for the upper punch, lower punch, and support core, effectively ensuring the coaxiality and circumferential alignment accuracy of each mold component, avoiding off-center loading and misalignment problems during the pressing process, and ensuring that the molding dimensions and dimensional accuracy of the spiral groove and knife edge groove meet the design requirements. The chamfered optimization structure of the mating surface can reduce the frictional loss of reciprocating motion. Combined with the selection of high-strength mold material, it further improves the wear resistance and structural strength of the mold, effectively extending the overall service life of the mold and reducing the amortization cost of the mold in mass production. 3. This invention features high process integration, convenient operation, and outstanding production efficiency. The complete set of copper-chromium contact windmill-type near-net-shape forming mold can be matched with a standard press to achieve fully automated operation. Through the independent drive control of the press's main cylinder, top cylinder, and center cylinder, the entire process of material preparation, floating pressing and forming, and step-by-step demolding and part removal can be completed sequentially without the need for additional auxiliary tooling or manual alignment. The demolding method adopts the downward demolding of the female mold and the synchronous extraction of the core, resulting in a smooth and stable demolding process that is less likely to scratch and damage the blank's shape and the groove structure. This effectively improves the finished product qualification rate and single-cycle production efficiency, and is fully adapted to the needs of mass industrial production of copper-chromium contacts. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall structure of the mold of the present invention; Figure 2 This is a top view of the mold cavity support body of the present invention; Figure 3 This is a bottom view of the upper punch of the present invention; Figure 4 This is a top view of the lower punch of the present invention; Figure 5 This is a schematic diagram of the supporting core structure of the present invention; Figure 6 This is a top view of the supporting core of the present invention; Figure 7 This is a top view of the mandrel adapter slot of the present invention; Figure 8 This is a schematic diagram of the assembly of the mold and the press of the present invention.

[0016] In the diagram, 10-mold cavity support, 101-mold cavity receiving hole, 102-arc-mouth adapter protrusion, 11-upper punch, 111-upper punch matching groove, 112-upper punch cover, 12-lower punch, 120-core rod matching through groove, 121-lower punch matching groove, 122-lower punch cover, 13-support core, 131-core connecting seat, 132-knife-edge core rod, 133-core cover, 134-core rod connecting rod, 14-female mold sleeve, 20-press, 21-main cylinder, 22-top cylinder, 23-mold frame base, 24-center cylinder. Detailed Implementation

[0017] The following is combined with Figures 1-8 The present invention will be described in detail. For ease of description, the orientations mentioned below are defined as follows: The directions of up, down, left, right, front, and back mentioned below are consistent with the directions of up, down, left, right, front, and back in the projection relationship of the respective main view or structural schematic diagram.

[0018] Example 1: A near-net-shape forming mold for copper-chromium contact fans, such as... Figure 1 As shown, it includes a mold cavity support 10, an upper punch 11, a lower punch 12, and a support core 13; like Figure 2 As shown, the mold cavity support 10 has a mold cavity receiving hole 101 that runs vertically through its axis, and the inner wall of the mold cavity receiving hole 101 is provided with multiple arc-shaped fitting protrusions 102 that extend vertically. like Figure 3 As shown, the lower end of the upper punch 11 has multiple upper punch forming grooves 111 that extend spirally around its radial plane; like Figure 4 As shown, the lower punch 12 has multiple lower punch forming grooves 121 that extend spirally around its radial plane, and the lower punch forming grooves 121 extend vertically through the lower punch 12. like Figure 5 As shown, the support core 13 includes a core connecting seat 131 and a plurality of vertically extending knife-edge core rods 132 fixed to the top of the core connecting seat 131.

[0019] like Figure 3 , Figure 4 As shown, from the same axial perspective, the spiral directions of the upper punch forming groove 111 and the lower punch forming groove 121 are consistent, and the cross-sectional shape and size of the upper punch 11 and the lower punch 12 are the same. like Figure 7 As shown, the arc-shaped adapter protrusion 102 extends into one side wall of the lower punch forming groove 121 and forms a mandrel adapter through groove 120 between the inner side wall of the lower punch forming groove 121. The cross-section of the blade mandrel 132 is consistent with the cross-sectional shape and size of the mandrel adapter slot 120, and multiple blade mandrels 132 slide and fit in each other from bottom to top in the respective mandrel adapter slot 120.

[0020] Example 2: Based on Example 1, such as Figure 3 As shown, the side opening formed between the upper punch forming groove 111 and the outer side wall of the upper punch 11 is chamfered, and the side opening formed between the lower punch forming groove 121 and the outer side wall of the lower punch 12 is chamfered. The upper punch 11 slides down into the mold cavity receiving hole 101, and each arc-shaped fitting protrusion 102 slides down into the side opening of each upper punch fitting groove 111. The lower punch 12 slides from bottom to top in the mold cavity receiving hole 101, and each arc-shaped fitting protrusion 102 slides in a corresponding manner in the side opening of each lower punch fitting groove 121.

[0021] Example 3: Based on Example 2, like Figure 8 As shown, the upper punch 11 is fixedly connected to the main cylinder 21 of the press 20 through the upper punch cover 112, and the mold cavity support 10 is fixed in a ring-shaped female mold sleeve 14 coaxial with it. The female mold sleeve 14 is fixed on the top cylinder 22 of the press 20. The lower punch 12 is fixedly connected to the mold base 23 of the press 20 via the lower punch cover 122; The support core 13 is fixedly installed on the top of a mandrel connecting rod 134 via a core cover 133. The mandrel connecting rod 134 is fixedly connected to the central cylinder 24 of the press 20.

[0022] It should be noted that the press 20 used in this application is a product of the prior art and is not specifically limited here. This application does not make any improvements to the structure of the press 20. The main cylinder 21, top cylinder 22, mold base 23 and center cylinder 24 on the press 20 are all components of the prior art. Those skilled in the art can choose them as needed, as long as the technical solution of this application can be achieved.

[0023] In practical applications, the copper-chromium contact fan-wheel type near-net-shape forming mold of this invention needs to be used with a press 20. The working cycle of this mold is divided into three core processes: material preparation, pressing and forming, and demolding and part removal. The specific process is as follows: Material preparation process: The central cylinder 24 of the press 20 drives the support core 13 to move upward to the set loading height through the core rod connecting rod 134, so that the upper end face of each blade core rod 132 and the upper end face of the lower punch 12 form a matching loading reference surface. Simultaneously, the top cylinder 22 of the press 20 drives the female mold sleeve 14 and the mold cavity support 10 to move upward to the loading station. At this time, the upper end face of the lower punch 12, the inner side wall of the mold cavity receiving hole 101, the side wall of the arc-shaped fitting protrusion 102, and the side wall of the cutting mandrel 132 together form a closed molding cavity. A release agent is evenly applied to the inner side wall of the molding cavity. The release agent is a mixture of zinc stearate and anhydrous ethanol in a certain proportion, with the mass percentage of zinc stearate to anhydrous ethanol being 10wt%:90wt%. Finally, a predetermined amount of copper-chromium contact molding material powder is filled into the molding cavity to complete the loading operation.

[0024] Compression molding process: After the material is loaded, the main cylinder 21 of the press 20 drives the upper punch 11 to move vertically downward. The upper punch 11 extends from top to bottom into the mold cavity receiving hole 101 of the mold cavity support body 10. The arc-shaped fitting protrusions 102 on the inner side of the mold cavity receiving hole 101 slide into the side openings of the upper punch matching grooves 111 of the upper punch 11, providing circumferential limit and vertical guidance for the downward movement of the upper punch 11, preventing the upper punch 11 from circumferentially deflecting and ensuring the alignment accuracy of the upper and lower dies. The upper punch 11 and lower punch 12 are made of DC53 or M2 high-speed steel, the mold cavity support 10 is made of WC, and the support core 13 is made of ASP23. The upper punch 11 continues to descend, applying axial pressure to the molding material in the cavity. At the same time, the top cylinder 22 can cooperate to drive the mold cavity support 10 to descend, achieving floating pressing and holding pressure, so that the material is uniformly and densely formed under the joint constraint of the upper punch 11, the lower punch 12, the mold cavity support 10 and the support core 13.

[0025] Since both the upper punch forming groove 111 and the lower punch forming groove 121 are spirally extended around the radial plane and the spiral direction is consistent, a continuous spiral groove structure is formed on the outer side of the formed copper-chromium contact blank, and the overall shape is a whirlwind. At the same time, the knife-edge mandrel 132 forms a through knife-edge groove structure at the corresponding position of the blank, so that the finished size can be close to the actual size without a lot of subsequent machining, and near-net-shape forming can be achieved. During the pressing process, the side openings between the upper punch forming groove 111 and the outer wall of the upper punch 11, and the side openings between the lower punch forming groove 121 and the outer wall of the lower punch 12, are all chamfered. This reduces the frictional resistance when the arc-shaped fitting protrusion 102 slides, and improves the smoothness of mold operation and service life.

[0026] Demolding and part removal process: After the pressing and holding pressure is completed, the main cylinder 21 of the press 20 drives the upper punch 11 to move vertically upward to reset and completely exit the mold cavity receiving hole 101. Then, the top cylinder 22 drives the female mold sleeve 14 and the mold cavity support body 10 to move vertically downward, so that the formed copper-chromium contact blank gradually comes out of the mold cavity receiving hole 101. Simultaneously, the central cylinder 24 drives the support core 13 to move downward through the core rod connecting rod 134, so that each knife-edge core rod 132 is pulled out from the corresponding slot of the blank. Once the mold cavity support 10 descends to the point where the copper-chromium contact blank is completely detached from the mold cavity receiving hole 101 and the knife-edge core rod 132 is completely detached from the blank, the formed copper-chromium contact blank can be removed. Subsequently, each cylinder of the press 20 drives the corresponding mold components to reset to the loading station and enter the next forming cycle.

Claims

1. A near-net-shape forming mold for copper-chromium contact pins in the shape of a fire wheel, characterized in that, It includes a mold cavity support (10), an upper punch (11), a lower punch (12), and a support core (13). The mold cavity support (10) has a mold cavity receiving hole (101) that runs vertically through its axis, and the inner wall of the mold cavity receiving hole (101) is provided with multiple arc-shaped fitting protrusions (102) that extend vertically. The lower end of the upper punch (11) has multiple upper punch forming grooves (111) that extend spirally around its radial plane. The lower punch (12) has multiple lower punch forming grooves (121) that extend spirally around its radial plane, and the lower punch forming grooves (121) penetrate the lower punch (12) in the vertical direction. The supporting core (13) includes a core connector (131) and a plurality of vertically extending blade cores (132) fixed to the top of the core connector (131).

2. The near-net-shape forming mold for a copper-chromium contact fan-wheel type according to claim 1, characterized in that, From the same axial perspective, the spiral direction of the upper punch matching groove (111) and the lower punch matching groove (121) is consistent, and the cross-sectional shape and size of the upper punch (11) and the lower punch (12) are the same.

3. The near-net-shape forming mold for a copper-chromium contact fan-wheel type according to claim 1, characterized in that, The side opening formed between the upper punch forming groove (111) and the outer side wall of the upper punch (11) is chamfered, and the side opening formed between the lower punch forming groove (121) and the outer side wall of the lower punch (12) is chamfered. The upper punch (11) slides from top to bottom in the mold cavity receiving hole (101), and each of the arc-shaped fitting protrusions (102) slides in the side opening of each of the upper punch fitting grooves (111); The lower punch (12) slides from bottom to top in the mold cavity receiving hole (101), and each of the arc-shaped fitting protrusions (102) slides in a corresponding manner in the side opening of each of the lower punch fitting grooves (121).

4. The near-net-shape forming mold for a copper-chromium contact fan-wheel type according to claim 1, characterized in that, The arc-shaped adapter protrusion (102) extends into one side wall of the lower punch forming groove (121) to form a mandrel adapter through groove (120) between the mandrel adapter through groove (121) and the inner side wall of the lower punch forming groove (121). The cross-section of the blade mandrel (132) is consistent with the cross-sectional shape and size of the mandrel adapter slot (120), and the multiple blade mandrels (132) slide in each of the mandrel adapter slots (120) from bottom to top.

5. A near-net-shape forming mold for a copper-chromium contact fan-wheel type according to claim 1, characterized in that, The upper punch (11) is fixedly connected to the main cylinder (21) of the press (20) through the upper punch cover (112). The mold cavity support (10) is fixed in a ring-shaped female mold sleeve (14) coaxial with it. The female mold sleeve (14) is fixed on the top cylinder (22) of the press (20). The lower punch (12) is fixedly connected to the mold base (23) of the press (20) via the lower punch cover (122); The supporting core (13) is fixedly installed on the top of a mandrel connecting rod (134) by a core cover (133), and the mandrel connecting rod (134) is fixedly connected to the central cylinder (24) of the press (20).

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