A molding process for complex structures

Abstract

The application provides a forming process of a complex structural part, and mainly comprises the following steps: firstly, a compaction sintering die and an extrusion forming die are respectively designed according to the shape of a rough blank and the shape of the structural part; metal powder added into the die cavity of the compaction sintering die is compacted in multiple directions to obtain a rough blank; the rough blank is put into a sintering equipment together with the compaction sintering die to be sintered, and then the compaction sintering die is demoulded after sintering to obtain a sintered blank; and the sintered blank is subjected to multi-directional extrusion forging through the extrusion forming die, thereby obtaining the final product. The application combines the powder metallurgy and the multi-directional extrusion forging process, reduces the forming difficulty of the complex structural part, ensures the strength and coherent organization of the connecting part of each part of the final structural part, and ensures the overall forming precision and strength of the final structural part.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mechanical structure forming, in particular to a forming process of a complex structure. BACKGROUND

[0002] With the continuous development of modern mechanical industry, the demand for complex structures (such as complex structures of branch type and asymmetric section type) in the fields of general mechanical equipment, aerospace equipment, transportation tools and heating pipe is increasing, and the overall or local parts are required to have specific strength, hardness and other functional properties. The above factors greatly increase the difficulty of preparing these complex structures.

[0003] The preparation methods of the existing technology mainly include mechanical milling, casting, forging, die casting and powder sintering. However, when these methods are used to prepare complex structures, there are some shortcomings: when the mechanical milling method is used for preparation, the processing time is long, the equipment requirement is high, the material utilization rate is low, and the preparation cost is extremely high. The performance requirements of such components cannot be guaranteed due to the defects such as porosity, pores and inclusions in traditional casting. Traditional forging process can only realize the preparation of rough blanks, and a large number of subsequent machining processes and working hours are still required, and the production cost is still difficult to effectively reduce. Components containing complex spatial shapes often need multiple mold modules to realize multiple demolding surfaces, so that the die casting and powder sintering technology also cannot mass-produce complex structures.

[0004] Therefore, it is necessary to design a forming process of a complex structure to solve the technical problems of high forming difficulty, high forming cost, incompatible forming precision and mechanical properties, material waste and the like in the prior art. SUMMARY

[0005] In order to solve the problems in the prior art, the present application provides a forming process of a complex structure, which combines powder metallurgy and multi-directional extrusion forging process to reduce the forming difficulty of the complex structure, on the one hand to ensure the strength and coherent organization of the connection between each part of the final structure, and on the other hand to ensure the overall forming precision and strength of the final structure.

[0006] In order to achieve the above purpose, the specific scheme adopted by the present application is as follows:

[0007] A forming process of a complex structure mainly comprises the following steps:

[0008] Step one, according to the structure of the final required structure of the structure, the shape of the rough blank is determined, the rough blank has the initial contour of the structure, the compacting and sintering mold and the extrusion forming mold are designed according to the shape of the rough blank and the structure respectively, the compacting and sintering mold comprises a compacting mold sleeve and a plurality of compacting punches, the mold cavity of the compacting mold sleeve is formed by at least two compacting mold blocks through clamping, the compacting mold sleeve has a plurality of compacting channels after clamping, the compacting punches are matched with the corresponding compacting channels, and the directions of movement of the plurality of compacting punches along the compacting channels to the mold cavity are not completely same or completely different; the extrusion forming mold comprises an extrusion mold sleeve and a plurality of extrusion punches, the mold cavity of the extrusion mold sleeve is formed by at least two extrusion mold blocks through clamping, the extrusion mold sleeve has a plurality of extrusion channels after clamping, the extrusion punches are matched with the corresponding extrusion channels, and the directions of movement of the plurality of extrusion punches along the extrusion channels to the mold cavity are not completely same or completely different;

[0009] Step two, the compacting mold sleeve is clamped, then metal powder is added into the mold cavity through the plurality of compacting channels, and multi-directional compacting is performed through the plurality of compacting punches after the addition, so that the rough blank is obtained;

[0010] Step three, the rough blank is placed in the sintering equipment together with the compacting and sintering mold for sintering, and the sintered blank is obtained after demolding;

[0011] Step four, the sintered blank is placed in the mold cavity through the clamping of the extrusion mold sleeve, and then multi-directional extrusion forging is performed on the sintered blank by the extrusion punches, so that the structure is obtained.

[0012] Further, the power for clamping the compacting mold sleeve or the extrusion mold sleeve is provided by the press equipment or the mold frame device; the power for the compacting punches or the extrusion punches is provided by the press equipment or the mold frame device.

[0013] Further, in step one, at least one compacting mold block and at least one extrusion mold block have the same structure, so that the compacting mold sleeve and the extrusion mold sleeve are at least partially same.

[0014] Further, in step two, the metal powder is 7075 aluminum alloy powder.

[0015] Further, in step three, the sintering temperature is 540-580 DEG C, the heating rate is 50 DEG C / min, the sintering pressure is 40 MPa, and the holding time is 4 h.

[0016] Further, in step four, the extrusion mold sleeve is provided with a heating and holding device outside after clamping, the extrusion forging temperature is 410-470 DEG C, and the loading speed is 8 mm / s.

[0017] Further, in step four, during the extrusion forging, the temperature difference between the sintered blank and the extrusion mold sleeve is less than 50 DEG C.

[0018] Beneficial effects:

[0019] (1) The present application reduces the difficulty of forming complex structural parts by combining powder metallurgy and multi-directional extrusion forging process, on the one hand, ensuring the strength and coherent organization of the complex structure connection of each part of the final complex structural part, on the other hand, ensuring the overall forming precision and strength of the final formed structural part. At the same time, when powder compaction and extrusion forging are carried out, one punch is responsible for the main pressing task, and the other punches cooperate with the punch to prevent mold damage failure caused by uneven load.

[0020] (2) In the present application, the rough blank and the overall appearance profile of the structural part are nearly consistent, the main difference is the forming integrity of the local keyway, hole or boss and other subtle structures. In this way, when designing the compaction sintering die and the extrusion forming die, the compaction die sleeve and the extrusion die sleeve are at least partially the same, after completing the powder compaction step, only the different modules need to be replaced and the compaction punch is replaced by the extrusion punch, which can greatly reduce the production time of the complex structural part and reduce the processing cost required for preparing additional molds.

[0021] (3) The compaction die sleeve and the extrusion die sleeve in the present application are composed of several modules, the modules at the easy-to-damage parts can be replaced individually when they reach the service life, without the need for replacing the entire die sleeve, which can effectively reduce the die replacement cost in the later production. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is the principle diagram of multi-directional compaction and multi-directional extrusion forging in the present application.

[0023] Figure 2 It is the assembly principle diagram of the die sleeve and the punch in the present application.

[0024] Figure 3 It is the forming process of structural part SP.1 provided in Example 1.

[0025] Figure 4 It is the assembly schematic diagram of the compaction sintering die in Example 1.

[0026] Figure 5 It is the assembly schematic diagram of the extrusion forming die in Example 1.

[0027] Figure 6 It is the forming process of structural part SP.2 provided in Example 2.

[0028] Figure 7 It is the assembly schematic diagram of the compaction sintering die in Example 2.

[0029] Figure 8 It is the assembly schematic diagram of the extrusion forming die in Example 2.

[0030] The meanings of the symbols in the figures are explained as follows:

[0031] Figure 1 In the figure, direction 1, direction 2, direction 3, direction 4, direction 5, direction 6 refer to different extrusion directions; α, β, γ refer to the angles between different local structures of the complex part;

[0032] Figure 2 In the figure, F1 corresponds to the punch of direction 1, F2 corresponds to the punch of direction 2, F3 corresponds to the punch of direction 3, F4 corresponds to the punch of direction 4, F5 corresponds to the punch of direction 5, F6 corresponds to the punch of direction 6, M1, M2, M3, M4, M5, M6, M7, M8 refer to the modules at different positions;

[0033] Figure 3 In the figure, Metal power represents metal powder, P1 is the rough blank in Example 1, SP.1 is the structural part in Example 1; stage ① represents the powder compaction stage; stage ② represents the extrusion forging stage;

[0034] Figure 4 In the figure, A1, A2, A3, A4, A5 represent the compaction punches used in Example 1, B1, B2, B3, B4 represent the compaction modules used in Example 1;

[0035] Figure 5 In the figure, A1*, A2*, A3*, A4*, A5* represent the extrusion punches used in Example 1, B1*, B2*, B3*, B4* represent the extrusion modules used in Example 1;

[0036] Figure 6 In the figure, P2 is the rough blank in Example 2, SP.2 is the structural part in Example 2;

[0037] Figure 7 In the figure, C1, C2, C3, C4 represent the compaction punches used in Example 2, D1, D2, D3 represent the compaction modules used in Example 2;

[0038] Figure 8 In the figure, C1*, C2*, C3*, C4* represent the extrusion punches used in Example 2, D1*, D2*, D3* represent the extrusion modules used in Example 2. DETAILED DESCRIPTION

[0039] The technical solutions of the present application will be described in detail below with specific examples. Obviously, the described examples are only a part of the embodiments of the present application, but not all the embodiments. Based on the examples in the present application, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present application.

[0040] It is to be understood that the terms "including", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0041] A complex structure forming process, which combines powder metallurgy and multi-directional extrusion forging forming technology. Please refer to Figure 1 and Figure 2 , the process specifically includes the following steps:

[0042] (1) According to the structure of the final required formed structure, the shape of the rough blank is determined, which has the initial contour of the structure,

[0043] According to the shape of the rough blank and the structure, a compaction sintering die and an extrusion forming die are designed, both of which include a die set and a punch, the die cavity of the die set is formed by assembling a plurality of modules (such as M1-M8 in Figure 2 , the die set after assembly has a plurality of channels, the punch is matched with the corresponding channel, and a plurality of punches (such as F1-F6 in Figure 2 ) move in different directions along the direction of the cavity; during powder compaction and multi-directional extrusion forging, the modules and punches are installed on the corresponding modules of the press equipment or die frame device for multi-directional compaction or multi-directional extrusion forging; for the sake of convenience, the die set in the compaction sintering die is referred to as a compaction die set, the die cavity of the compaction die set is formed by assembling at least two compaction modules, the channels in the compaction die set are referred to as compaction channels, and the punches matched with the compaction channels are referred to as compaction punches. The die set in the extrusion forming die is referred to as an extrusion die set, the die cavity of the extrusion die set is formed by assembling at least two extrusion modules, the channels in the extrusion die set are referred to as extrusion channels, and the punches matched with the extrusion channels are referred to as extrusion punches;

[0044] (2) Fill the metal powder, the compaction sintering die realizes the assembly of the die cavity, and after assembly, the metal powder is added through different direction compaction channels, and after addition, the metal powder is compacted through the compaction punches of different compaction channels to obtain a rough blank. The multi-channel powder filling path and multi-directional compaction punch in this process can greatly save the powder filling time and compaction time, effectively improve the process preparation efficiency, and also can improve the dimensional forming integrity of the rough blank.

[0045] (3), the rough blank is put into the sintering equipment together with the compacted sintering mold for sintering, and after sintering, the sintered blank is obtained by demolding;

[0046] (4) the sintered blank is subjected to multi-directional forging forming, and the sintered blank is put into an extrusion forming mold, the extrusion forming mold is combined with extrusion punches of different directions to realize the compaction of the whole and local blank, realize the forming of the local complex structure such as tooth shape, spline, special-shaped boss and hole, and obtain a structural part.

[0047] In the present application, at least one compaction module and at least one extrusion module have the same structure, so that the compaction die sleeve and the extrusion die sleeve are at least partially the same, when sintering is performed, only the different modules need to be disassembled and replaced with extrusion punches, which can greatly reduce the production time of complex structural parts and reduce the processing cost required for preparing additional molds.

[0048] Example 1

[0049] Taking the structural part SP.1 as an example, please refer to Figures 3 to 5 , the implementation steps are as follows:

[0050] Step one, according to the shape of the required structural part SP.1, the shape of the rough blank P1 with the initial contour is determined, the compaction sintering mold and the extrusion forming mold are designed according to the shape of the rough blank and the structural part respectively, the compaction punches A1-A5 or the extrusion punches A1*-A5* are installed on the corresponding modules of the press equipment or the mold frame device, and the compaction modules B1-B4 or the extrusion modules B1*-B4* are installed on the corresponding modules of the press equipment or the mold frame device;

[0051] Step two, powder compaction, the compaction punch A2 runs to the specified stroke, cooperates with the compaction modules B1-B4 to realize the mold cavity closing, and then fills the 7075 aluminum alloy metal powder at the compaction channels of the compaction punches A1, A3, A4 and A5, the added metal powder is compacted by the compaction punches A1-A5 in different compaction channels, and the rough blank P1 is prepared. During the whole powder compaction process, the extrusion punch A1 runs in the pattern hole compaction channel above the compaction module B1, the compaction punch A2 runs in the circular extrusion channel below the compaction module B2, the compaction punches A3 and A4 run in the circular and left circular combined extrusion channels on the right side of the compaction modules B1-B2 respectively, and the compaction punch A5 runs in the square combined compaction channel in front of the compaction modules B3-B4. In addition, the main functions of the compaction punches A1-A5 are compaction and auxiliary limiting, and the powder filling channel and the compaction punch in multiple directions during the powder compaction process can greatly reduce the process time;

[0052] Step three, put the compaction sintering mold with the rough blank P1 in step two into the sintering equipment as a whole for sintering, the sintering temperature is 540℃, the heating rate is 50℃ / min, the sintering pressure is 40 MPa, and the holding time is 4 h, then demold after sintering to obtain a sintered blank;

[0053] Step four, multi-directional extrusion forging is performed on the sintered blank obtained in step three to prepare a structural part SP.1. The mold is replaced, the sintered blank is put into the extrusion forming mold, the extrusion punch A1* operates in the extrusion channel of the extrusion module B1*, the extrusion punch A2* operates in the extrusion channel of the extrusion module B2*, the extrusion punches A3* and A4* respectively operate in the combined extrusion channels of the right circular and left circular of the extrusion module B1*-B2*, and the extrusion punch A5* respectively operates in the combined extrusion channels in front of the extrusion modules B3*-B4* to form a complete extrusion action, so as to realize the compaction of the whole and the local sintered blank. The extrusion punch A1* is mainly responsible for forming the spline ball groove, the extrusion punch A2* is mainly responsible for forming the six-sided groove, the extrusion punch A3* is mainly responsible for forming the cylindrical boss with holes, the extrusion punch A4* is mainly responsible for forming the keyway, and the extrusion punch A5* is mainly responsible for forming the square prism. During the whole extrusion forming process, the extrusion punches A1*-A5* function as local deformation, compaction and auxiliary positioning.

[0054] It should be noted that when the mold is replaced in step four, only the compaction punches A1-A5 are replaced and installed as extrusion punches A1*-A5*, the compaction module B1 is replaced as the extrusion module B1*, and the compaction module B2 is replaced as the extrusion module B2*. The compaction modules B3 and B4 do not need to be replaced because they have the same structure as the extrusion modules B3* and B4*.

[0055] It should be noted that the extrusion die set after clamping is provided with a heating and heat preservation device, and the extrusion forging temperature is 420℃, and the loading speed is 8 mm / s.

[0056] Example 2

[0057] Taking the structural part SP.2 as an example, please refer to Figures 6 to 8 , and the implementation steps are as follows:

[0058] Step one, the shape of the rough blank P2 with an initial contour is determined according to the shape of the required molded structural part SP.2, and the compaction sintering mold and the extrusion forming mold are designed according to the shapes of the rough blank and the structural part. The number of molds required depends on the complexity of the structure of the molded structural part. Generally, the more complex the structure of the part, the more molds are required. The compaction punches C1-C4 or the extrusion punches C1*-C4* are installed on the corresponding modules of the press equipment or the mold frame device, and the compaction modules D1-D3 or the extrusion modules D1*-D3* are installed on the corresponding modules of the press equipment or the mold frame device.

[0059] Step two, carry out the powder compaction process, specifically, fill 7075 aluminum alloy metal powder, compact the mold D1-D3 and the corresponding compaction punch C4 to realize the mold closing of the mold cavity, the compaction channel of the compaction punch C3 as the main powder adding path, the compaction channel of the compaction punch C1, C2 as the auxiliary powder adding path. The compaction punch C4 runs in its corresponding compaction channel to the specified stroke, and then adds metal powder from the compaction channel of the compaction punch C1, C2 and C3. The filled metal powder is compacted by the compaction punches C1-C4 of different compaction channels at the same time to realize compaction, and a rough blank P2 is prepared. During the whole powder compaction process, the main functions of the compaction punches C1-C4 are compaction and auxiliary limiting;

[0060] Step three, put the compaction sintering mold in which the rough blank P2 is placed into the sintering equipment as a whole to carry out sintering. The sintering temperature is 560℃, the heating rate is 50 ℃ / min, the sintering pressure is 40 MPa, and the holding time is 4 h. After sintering, the mold is demolded to obtain a sintered blank;

[0061] Step four, multi-directional extrusion forging is carried out on the sintered blank obtained in step three to prepare a structural part SP.2. Specifically, the mold is replaced, the sintered blank is placed into the extrusion forming mold, the extrusion punches C1*, C2*, C4* run in the extrusion channels of the extrusion modules D1*-D2*, and the extrusion punch C3* runs in the extrusion channel of the extrusion module D3*, thereby cooperating to form a complete extrusion action to realize the compaction of the sintered blank as a whole and locally. The extrusion punch C3* is responsible for forming the key body structure, the extrusion punch C1* is responsible for forming the cylindrical boss structure, and the extrusion punch C2* is responsible for forming the boomerang-shaped structure. During the whole extrusion forming process, the functions of the extrusion punches C1*, C2*, C3* are local deformation, compaction and auxiliary limiting, and the extrusion punch C4* plays the roles of auxiliary limiting and compaction.

[0062] It should be noted that when the mold is replaced in the above step four, only the compaction punches C2-C3 are replaced and installed into the extrusion punches C2*-C3*, and the compaction module D3 is replaced into the extrusion module D3*. The compaction punch C1 and the extrusion punch C1*, the compaction punch C4 and the extrusion punch C4*, the compaction module D1 and the multi-directional extrusion module D1*, and the compaction module D2 and the extrusion module D2* are the same modules and do not need to be replaced.

[0063] It should be noted that a heating and heat preservation device is arranged outside the closed extrusion die set, the extrusion forging temperature is 460℃, and the loading speed is 8 mm / s.

[0064] The foregoing presents and describes the primary features, methods of use, and advantages of the present application. It is to be understood that the application is not limited to the above-described embodiments and that various modifications and improvements can be made without departing from the spirit and scope of the application. Such modifications and improvements are intended to fall within the scope of the application as defined by the appended claims and their equivalents.

Claims

1. A forming process for a complex structure, characterized in that, The method mainly comprises the following steps: Step one, according to the structure of the final required structure part, the shape of the rough blank is determined, the rough blank has the initial contour of the structure part, the compacting and sintering die and the extrusion forming die are respectively designed according to the shape of the rough blank and the structure part, the compacting and sintering die comprises a compacting die sleeve and a plurality of compacting punches, the die cavity of the compacting die sleeve is formed by clamping at least two compacting die blocks, the compacting die sleeve has a plurality of compacting channels after clamping, the compacting punch is matched with the corresponding compacting channel, and the directions of movement of the plurality of compacting punches along the compacting channels to the die cavity are not completely same or completely different; the extrusion forming die comprises an extrusion die sleeve and a plurality of extrusion punches, the die cavity of the extrusion die sleeve is formed by clamping at least two extrusion die blocks, the extrusion die sleeve has a plurality of extrusion channels after clamping, the extrusion punch is matched with the corresponding extrusion channel, and the directions of movement of the plurality of extrusion punches along the extrusion channels to the die cavity are not completely same or completely different; at least one compacting die block is the same as at least one extrusion die block, so that the compacting die sleeve and the extrusion die sleeve are at least partially same; Step two, the compacting die sleeve is clamped, then the metal powder is added into the die cavity through the plurality of compacting channels, and the multi-directional compacting is performed through the plurality of compacting punches after the addition, so as to obtain the rough blank; wherein, when the powder is compacted, one compacting punch is responsible for the main pressing task, and the other compacting punches cooperate with the compacting punch to perform extrusion; Step three, the rough blank is placed in the sintering equipment together with the compacting and sintering die for sintering, and the sintered blank is obtained after the sintering and demolding; Step four, the sintered blank is placed in the die cavity through the clamping of the extrusion die sleeve, and then the multi-directional extrusion forging is performed on the sintered blank by using the extrusion punch, so as to obtain the structure part; wherein, when the extrusion forging is performed, one extrusion punch is responsible for the main pressing task, and the other extrusion punches cooperate with the extrusion punch to perform extrusion; only the different die blocks need to be disassembled and the compacting punch needs to be replaced with the extrusion punch for use during the extrusion forging.

2. A process for forming a complex structure according to claim 1, wherein The power for clamping the compacting die sleeve or the extrusion die sleeve is provided by the press equipment or the die frame device; the power for the compacting punch or the extrusion punch is provided by the press equipment or the die frame device.

3. The process of claim 1, wherein, In step two, the metal powder is 7075 aluminum alloy powder.

4. The process of claim 3, wherein the complex structure is a complex structure of a vehicle. In step three, the sintering temperature is 540-580 ℃, the heating rate is 50 ℃ / min, the sintering pressure is 40 MPa, and the holding time is 4 h.

5. The process of claim 3, wherein the complex structure is a complex structure of a vehicle. In step four, the extrusion die sleeve after clamping is provided with a heating and holding device outside, the extrusion forging temperature is 410-470 ℃, and the loading speed is 8 mm / s.

6. The process of claim 3, wherein the complex structure is a complex structure of a vehicle. In step four, the temperature difference between the sintered blank and the extrusion die sleeve is less than 50 ℃ during the extrusion forging.

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