Reverse extrusion type composite pipe forming die

Abstract

The utility model discloses a backward extrusion type composite pipe forming die. The die comprises a hollow extrusion cylinder (4), an upper cover (1) covering the upper end opening of the hollow extrusion cylinder, a positioning cylinder (3) embedded in the inner wall of the hollow extrusion cylinder, a lower die (5) embedded in the lower end opening of the hollow extrusion cylinder, and an extrusion rod (2) connected with the upper cover and the lower die in a penetrating manner. According to the die, a backward extrusion mode is adopted, a pipe sample can be formed without being guided and dragged, the section of the pipe is flattened through the dead weight of the positioning cylinder in the forming process, and the problem of bending deformation in the pipe forming process is effectively solved through a self-locking structure of the lower die and the extrusion cylinder; and the yield of the composite material, especially the composite material difficult to form, is greatly improved.

Description

Technical Field

[0001] The utility model relates to a pipe forming die, in particular to a reverse extrusion type composite pipe forming die, and belongs to the technical field of composite material processing. Background Art

[0002] In the prior art, particle-reinforced aluminum-based pipes are generally obtained by preparing a blank by powder metallurgy and then extruding it in the positive direction. However, during the forming process, the following problems exist:

[0003] (1) The forming effect is poor. Since there is no traction or guidance on the formed specimen, the specimen is bent;

[0004] (2) Since the particle reinforcement material has a high hardness and it is difficult to remove the reinforcement particles by chemical methods, they will get stuck in the gap between the punch and the female die of the mold after extrusion, making it impossible to demold the mold and making it difficult to reuse it;

[0005] (3) The pressure required for the forward extrusion process is relatively high, and the requirements for equipment are relatively high;

[0006] Therefore, how to develop a pipe preparation mold with low equipment requirements, better molding effect and high mold reuse rate is an urgent problem that needs to be solved. Utility Model Content

[0007] In view of the problems existing in the prior art, the purpose of the utility model is to provide a reverse extrusion composite pipe forming die. The die adopts a reverse extrusion method and can form the pipe sample without guiding and pulling it. The die uses the deadweight of the positioning cylinder to flatten the cross section of the pipe during the forming process, and the self-locking structure of the lower die and the extrusion cylinder effectively solves the problem of bending and deformation during the pipe forming process, thereby greatly improving the yield of composite materials, especially difficult-to-form composite materials.

[0008] In order to achieve the above technical purpose, the utility model provides a reverse extrusion composite pipe forming die, which is characterized by comprising a hollow extrusion cylinder (4), an upper cover (1) covering the upper end of the hollow extrusion cylinder, a positioning cylinder (3) nested in the inner wall of the hollow extrusion cylinder, a lower die (5) embedded in the lower end of the hollow extrusion cylinder, and an extrusion rod (2) penetrating and connecting the upper cover and the lower die.

[0009] The composite material pipe forming die provided by the utility model, when in use, first installs the lower die into the extrusion barrel, forms a closed self-locking environment through clearance fit, then puts the blank to be extruded into the extrusion barrel, puts the positioning barrel, the extrusion rod and the upper cover in sequence, and then puts the entire die into the heating furnace, and extrudes after high-temperature heating, so as to obtain a formed pipe. The die adopts a reverse extrusion forming method, which effectively solves the problem that a large extrusion force is required during positive extrusion in the prior art and the extrusion process is easy to bend. During the pipe extrusion forming process, since there is no friction between the billet and the extrusion barrel, the extrusion force is greatly reduced compared with the forward extrusion method, and within the full stroke range of the extrusion rod, the extrusion force is uniform and constant, and difficult-to-deform materials can be processed at a lower temperature with a higher extrusion coefficient.

[0010] As a preferred solution, the positioning cylinder is a hollow structure, and its aperture allows the extrusion rod to pass freely in the positioning cylinder and prohibits the lower mold from passing through.

[0011] As a preferred solution, the ratio of the inner diameter of the hollow extrusion cylinder, the outer diameter of the extrusion tube and the inner diameter of the positioning cylinder is 33-39:58-64:28-34.

[0012] As a preferred solution, the lower die is tightly fitted with the inner wall of the hollow extrusion barrel to form a self-locking structure. The self-locking structure formed by the lower die and the inner wall of the hollow extrusion barrel in the utility model ensures that the lower die does not fall out of the lower part of the extrusion barrel, and also effectively solves the problem that during the extrusion process, the metal liquid flows upward under pressure, driving the extrusion barrel to move upward at the same time, causing deviation in the straightness of the extruded pipe and eccentricity in the extrusion.

[0013] As a preferred solution, the inner wall of the positioning tube is also provided with an air guide groove. The main function of the air guide groove is to discharge the high-pressure gas inside the mold part during the tube extrusion molding process, thereby ensuring that the tube is not affected by the gas pressure during the molding process, avoiding the generation of tiny holes and cracks on the surface of the tube, and improving the surface density of the tube.

[0014] As a preferred solution, the number of the air guide grooves is 2 to 6.

[0015] As a preferred solution, the distribution of the air guide grooves is one of central symmetry, axial symmetry and equal interval distribution.

[0016] As a preferred solution, the length of the positioning cylinder is 30-50 mm; the length of the hollow extrusion cylinder is 250-270 mm. The lengths of the positioning cylinder and the hollow extrusion cylinder should be in accordance with the above requirements. The positioning cylinder with a certain length can ensure that its own weight can flatten the cross section of the pipe to avoid unevenness or cracking at the top of the pipe sample. On the other hand, it can also improve the forming rate of the pipe and facilitate demoulding.

[0017] Compared with the prior art, the beneficial technical effects of the utility model are:

[0018] 1) The tube forming die provided by the utility model adopts a reverse extrusion method, which effectively solves the problem in the prior art that a large extrusion force is required during positive extrusion and the tube is prone to bending during the extrusion process. During the tube extrusion forming process, since there is no friction between the billet and the extrusion barrel, the extrusion force is greatly reduced compared to the forward extrusion method, and within the full stroke range of the extrusion rod, the extrusion force is uniform and constant, and difficult-to-deform materials can be processed at a lower temperature with a higher extrusion coefficient.

[0019] 2) In the technical solution provided by the utility model, the lengths of the positioning cylinder and the hollow extrusion cylinder must be implemented in accordance with the above requirements. The positioning cylinder with a certain length can ensure that its own weight can press the cross-section of the pipe flat to avoid unevenness or cracking of the pipe sample. On the other hand, it can also improve the forming rate of the pipe and facilitate demolding.

[0020] 3) In the technical solution provided by the utility model, the reverse extrusion adopted is circumferential extrusion. Compared with the forward extrusion in the prior art, waste materials such as residual pressing are significantly reduced, and a higher yield rate can be achieved. It can be used for extrusion molding of larger-sized blanks, and all parts in the mold are detachable parts, which greatly shortens the cleaning time of the mold and the interval time in the continuous preparation process, greatly improving equipment utilization and production continuity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the forward extrusion used in Comparative Example 1;

[0022] Figure 2 This is a schematic diagram of the reverse extrusion die used in Example 1;

[0023] Among them, 1-upper cover, 2-extrusion rod, 3-positioning cylinder, 4-extrusion cylinder, 5-lower mold;

[0024] Figure 3 This is a schematic diagram of the pipe demoulding tooling of Example 1;

[0025] Among them, 6-demolding ejector pin, 7-demolding female mold. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention, but the present invention is not limited thereto.

[0027] Example 1

[0028] Provided is a composite material pipe forming die, comprising: a hollow extrusion barrel (4), an upper cover (1) covering the upper end of the hollow extrusion barrel, a positioning barrel (3) embedded in the inner wall of the hollow extrusion barrel, a lower die (5) embedded in the lower end of the hollow extrusion barrel, and an extrusion rod (2) penetrating and connecting the upper cover and the lower die, wherein the upper cover, the extrusion rod, the positioning barrel and the lower die are all matched with the extrusion barrel in a detachable manner, and the lower die and the extrusion barrel form a clearance match to form a self-locking.

[0029] When in use, first install the lower die 5 into the extrusion cylinder, form a closed environment through clearance fit, then put the blank to be extruded into the extrusion cylinder 4, then put in the positioning cylinder 3, the extrusion rod 2, and the upper cover 1, and then put the entire mold into a heating furnace, and extrude it after high-temperature heating to obtain a formed pipe.

[0030] The lower die 5 of the composite material pipe forming mold and the extrusion barrel 4 are fitted with a clearance, which ensures that the lower die does not fall out from the bottom of the extrusion barrel. At the same time, it can also solve the problem that the metal liquid flows upward under pressure during the extrusion process, driving the extrusion barrel to move upward at the same time, causing deviation in the straightness of the extruded pipe and eccentricity in the extrusion.

[0031] In this embodiment, the length of the positioning tube 3 is 30 mm. By adopting a longer positioning tube length, the cross section of the pipe can be pressed flat by its own weight, which is convenient for demoulding.

[0032] In this embodiment, the inner wall of the positioning cylinder 3 is provided with two air guide grooves arranged opposite to each other, which can discharge the air during the extrusion process, so that the extrusion process of the extrusion cylinder 4 is not affected by the air pressure, thereby improving the extrusion effect.

[0033] The pipe prepared by the composite material forming mold of this embodiment has uniform deformation, and the organization and mechanical properties along the length of the extruded product are basically consistent. It has high strength, stiffness and high-temperature mechanical properties. The blank prepared by the pipe forming mold developed by the utility model can be processed to prepare a thin-walled pipe with a wall thickness of 1 mm, and its room temperature tensile property reaches 520-620 MPa, and the tensile mechanical property at 300°C reaches 320-450 MPa.

[0034] Comparative Example 1

[0035] The green sheet is extruded by a forward extrusion die; Figure 1 As shown in the figure, the compact is placed in the mold, assembled and placed in a heating furnace, and then taken out for extrusion after heating. The tube is severely deformed and bent, and cracks appear. At the same time, due to the high hardness of the particle reinforcement material and the difficulty in removing the reinforcement particles by chemical methods, the reinforcement particles are stuck in the gap between the punch and the female die of the mold after the extrusion, making it impossible to demold the mold and difficult to reuse.

[0036] Comparative Example 2

[0037] This comparative example is exactly the same as the example, except that the length of the positioning tube is 10 mm, and the lower die and the extrusion tube are matched without clearance, and the lower die can fall out from the lower part of the extrusion tube without self-locking function. The pressed blank is placed in the mold, assembled and placed in a heating furnace, and taken out for extrusion after heating. It is observed that cracks appear on the upper part of the tube and extrusion eccentricity occurs.

[0038] Comparative Example 3

[0039] This comparative example is exactly the same as comparative example 2, except that the lower die and the extrusion barrel have clearance fit and can be self-locking. The pressed blank is placed in the die, assembled and placed in a heating furnace, and taken out and extruded after heating. It is observed that cracks appear on the upper part of the pipe, and the upper part of the pipe is uneven.

Claims

1. A reverse extrusion composite pipe forming die, characterized in that: It comprises a hollow extrusion barrel (4), an upper cover (1) covering the upper end of the hollow extrusion barrel, a positioning barrel (3) nested in the inner wall of the hollow extrusion barrel, a lower die (5) embedded in the lower end of the hollow extrusion barrel, and an extrusion rod (2) penetrating and connecting the upper cover and the lower die.

2. The reverse extrusion composite pipe forming die according to claim 1, characterized in that: The positioning cylinder is a hollow structure, and its aperture allows the extrusion rod to pass freely in the positioning cylinder and prohibits the lower mold from passing through.

3. The reverse extrusion composite pipe forming die according to claim 2, characterized in that: The ratio of the inner diameter of the hollow extrusion cylinder, the outer diameter of the extrusion tube and the inner diameter of the positioning cylinder is 33-39:58-64:28-34.

4. The reverse extrusion composite pipe forming die according to claim 1, characterized in that: The lower die is tightly fitted to the inner wall of the hollow extrusion cylinder to form a self-locking structure.

5. The reverse extrusion composite pipe forming die according to claim 1, characterized in that: The inner wall of the positioning tube is also provided with air guide grooves; the number of the air guide grooves is 2 to 6.

6. The reverse extrusion composite pipe forming die according to claim 5, characterized in that: The distribution mode of the air guide grooves is one of central symmetry, axial symmetry and equal interval distribution.

7. The reverse extrusion composite pipe forming die according to claim 1, characterized in that: The length of the positioning cylinder is 30-50 mm; the length of the hollow extrusion cylinder is 250-270 mm.

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