Isothermal thermal forming progressive die and design method and forming method thereof

Abstract

The invention discloses an isothermal thermal forming progressive die and a design method and a forming method thereof, the progressive die is provided with a plurality of cavities, each cavity corresponds to a different process, and simultaneous forming of a plurality of processes is realized through one-time die pressing. The cavities are arranged according to each process implementation action and equipment interface, and lateral force is avoided as much as possible in cavity arrangement; the progressive die comprises an upper die, a pressing edge and a lower die from top to bottom; a part taking groove is formed in a cavity in each process of edge pressing; an ejector rod hole is formed in the lower die, guiding structures are arranged between the upper die and the pressing edge and between the lower die and the pressing edge, and die guiding is integrally designed. Positioning, taking and placing of blanks and parts in all working procedures are integrally designed. According to the progressive die, the one-die multi-process cavity design is adopted, the single-process single-set die design is replaced, multi-process forming is achieved through one-time die pressing, the die cost is reduced, meanwhile, the use efficiency of hot forming equipment is greatly improved, the development period of parts is shortened, and the development cost of the parts is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of aviation sheet metal parts manufacturing, and in particular relates to an isothermal hot forming progressive die and a design method and a forming method thereof. Background Art

[0002] Titanium alloy materials have been widely used in the field of aviation sheet metal due to their excellent material properties (high specific strength, corrosion resistance, high temperature resistance, etc.).

[0003] In aircraft structural parts, titanium alloy materials are widely used in key parts such as frames, doors, hydraulic pipelines, landing gear, skins, wing beams, etc. In aircraft engine parts, titanium alloys are widely used in parts working in high temperature environments, such as blades, casings, radiators, etc.

[0004] In the application of titanium alloys, sheet forming, especially thin sheet forming, has always been a difficult point in the forming field. Because the forming performance of titanium alloys at room temperature is poor, in order to improve the forming performance of the material, the titanium alloy plate is often heated before forming, which brings many uncertain factors to sheet forming and increases the complexity of the forming process. The cost of titanium alloy hot forming experiments is high and the cycle is long. At present, there is little research on the forming process and molds of titanium alloy parts that require multi-process forming in China.

[0005] For titanium alloy parts that are formed in multiple processes, each forming process requires a dedicated mold, and the parts are formed on an isothermal hot forming press. The mold work of each process must go through the process of heating up - forming - cooling down on the hot forming press, which takes about 3 days of equipment use. The equipment use time for the three processes is 9 days, and the equipment is in a high temperature state for most of the process. The existing mold form for multi-process forming titanium alloy parts leads to a long production cycle and high cost.

[0006] A Chinese invention patent with publication number CN110743927B discloses a magnesium alloy ring extrusion forming die, comprising an upper die assembly, a die assembly and a lower die assembly; the die assembly is fixedly arranged on the lower die assembly; the die assembly comprises an inner die and an outer die, a cavity is formed between the inner die and the outer die, and the outer wall surface of the inner die can be used to place a blank; the upper die assembly is connected to a press, and the blank is pressed down by the press to be extruded along the curved generatrix of the outer wall surface of the inner die; the provided solution can achieve near-isothermal forming, avoid material cracking, greatly improve the forming yield of large-sized magnesium alloy rings, shorten the manufacturing process of large-sized magnesium alloy rings, and reduce production costs, and the mold is simple and easy to operate, which can greatly shorten the extrusion forming process, effectively improve the formability of magnesium alloys, and facilitate a large degree of hole expansion deformation, but the invention still takes a lot of time and occupies a long time of the press. The Chinese invention patent with publication number CN101491873B discloses a two-step plastic forming method for automobile wheel hubs. The method is to extrude the blank in two steps under isothermal conditions using two sets of dies. In the first step, the blank is placed in an extrusion forming die to form the spoke part and preform the front and rear rim parts of the rim by extrusion; in the second step, the preformed part is placed in an expansion die to expand the front and rear rim parts of the rim at one time. Compared with the prior art, the invention has the characteristics of low forming force, low equipment investment, low production cost and high forming quality. At the same time, the invention also discloses an extrusion forming die and an expansion die that are compatible with the above method. Although the invention uses two sets of dies for rapid prototyping, it is not suitable for complex parts.

[0007] Therefore, it is necessary to design a mold that can realize multi-process forming under isothermal hot forming. Summary of the invention

[0008] In order to solve the above problems, the present invention aims to provide an isothermal hot forming progressive die and a design method and a forming method thereof.

[0009] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a design method of an isothermal hot forming progressive die, including a progressive die, wherein the progressive die is provided with a plurality of cavities, each cavity corresponds to a different process, and a plurality of processes are formed simultaneously by one molding.

[0010] Furthermore, the cavity arrangement adopts a symmetrical layout to avoid unbalanced loading of the equipment.

[0011] Furthermore, the edge holding surfaces of all processes in the cavity are of the same height, thus avoiding unbalanced loading of the equipment.

[0012] A progressive die for isothermal hot forming, comprising an upper die, a press edge and a lower die from top to bottom; a piece removal groove is provided in each process cavity of the press edge; a push rod hole is provided on the lower die; further, a guide structure is provided between the upper die and the press edge, and between the lower die and the press edge.

[0013] Furthermore, the ejector rod hole of the lower die matches the ejector rod of the equipment.

[0014] Furthermore, a preform positioning structure designed according to each process is arranged on the pressing edge.

[0015] A forming method of progressive die isothermal hot forming, comprising the following steps: Step 1: Place each preform at the corresponding position on the press edge according to each sequence positioning structure and preheat; Step 2: close the upper mold and the edge press; Step 3: The upper mold and the edge press move downward as a whole after mold closing until they are completely closed with the lower mold and then the pressure is maintained; Step 4: The upper die returns, and the ejector pin rises until the part is separated from the lower die, and the part is taken out.

[0016] Furthermore, the preformed parts in step 1 include but are not limited to the original blank, the first-order parts obtained after the original blank undergoes a first process, and the second-order parts obtained after the first-order parts undergo a second process.

[0017] Furthermore, the molding process is carried out at a constant temperature.

[0018] Compared with the prior art, the present invention has the following advantages: the progressive die of the present invention adopts a one-mold multi-process cavity design, replacing a single-process single-set mold design, and realizes multi-process forming in one molding. While reducing the mold cost, it greatly improves the use efficiency of the hot forming equipment, shortens the part development cycle and reduces the part development cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of parts of Example 1 of the present invention; Figure 2 Schematic diagram of the isothermal hot forming progressive die structure in the embodiment; Figure 3 Schematic diagram of the isothermal hot forming progressive die process in the embodiment; Figure 4 This is a schematic diagram of the bottom surface of the lower mold in the embodiment; Figure 5 This is a schematic diagram of the isothermal forming process in the embodiment; Figure 6 This is a schematic diagram of the second sequence of isothermal forming in the embodiment; Figure 7 This is a schematic diagram of the three isothermal forming steps in the embodiment; In the figure, 1-upper die; 2-lower die; 3-edge pressing; 4-piece removal slot; 5-elevator hole; 6-positioning structure; 7-guide structure; A-blank; B-first sequence part; C-second sequence part. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to the common technical knowledge and customary means in the field are included in the scope of the present invention.

[0022] The present invention uses a progressive die structure to realize the multi-process part forming of titanium alloy. The progressive die includes an upper die 1, a pressure edge 3, and a lower die 2 from top to bottom. A take-out groove 4 is provided in each process cavity of the pressure edge 3, and a push rod hole 5 is provided on the lower die 2. A guide structure 7 is provided between the upper die 1 and the pressure edge 3, and between the lower die 2 and the pressure edge 3. The push rod hole 5 on the bottom surface of the lower die 2 matches the equipment push rod. A preform positioning structure designed according to each process is provided on the pressure edge 3.

[0023] The design method of the progressive die is to set up multiple cavities in the progressive die, each cavity corresponds to a different process, and multiple processes are formed simultaneously in one molding. The cavity is arranged according to the action of each process and the equipment interface. The cavity arrangement tries to avoid lateral force and equipment overload. The overall design of the mold guide, the overall design of the positioning and placement of the blank, the height of the edge holding surface of all processes in the cavity is consistent, to ensure that the edge holding of multiple processes is stressed at the same time, and to ensure the balance of the equipment ejector.

[0024] The forming method of the progressive die comprises the following steps: Step 1: Design a progressive die according to the shape of the part to be prefabricated, place each preformed part on the corresponding processing position on the edge holder 3 and preheat; Step 2: The upper mold 1 and the edge pressing 3 are molded together; Step 3: The edge holder 3 maintains pressure, and the upper mold 1 and the edge holder 3 move downward as a whole after mold closing until they are completely molded with the lower mold 2 and then the pressure is maintained; Step 4: The upper die 1 returns, and the ejector pin rises until the part is separated from the lower die 2, and the part is taken out.

[0025] Example 1: Design a progressive die to prepare a triangular box-shaped part. The triangular box-shaped part is as follows: Figure 1 As shown, the overall shape is triangular, with a circular hole in the middle and a deep flange. Three pressing processes are required to obtain the finished product, namely preforming, drawing, and hole flanging. It is known that the material of the triangular box-shaped part is TA15, the material thickness is 1.2mm, and the hole flanging direction is axial.

[0026] A mold is designed by adopting the design method of the present invention, on which three processing steps can be completed. The mold is designed with three cavities. The first cavity realizes pre-forming convex hull, the second cavity realizes deep drawing to form a triangular box-shaped part, and the third cavity realizes convex hull to complete flanging.

[0027] Reference Figure 2 , in order to prepare the progressive die of the triangular box-shaped part, the upper die 1 is arranged from top to bottom, the upper die 1 is the concave die, the edge holder 3 and the lower die 2 are arranged, and the lower die 2 is the convex die; since the three processes are all double-action processes and the difference in the cavities is not large, the arrangement of the cavities has little effect on the equipment overload, so no special arrangement is made for the arrangement of the cavities of the three processes, and they are only arranged from left to right in the forming order. In order to ensure the balance of the equipment's ejector force and avoid equipment overload, the edge holder surfaces of the three processes are at the same height, ensuring that the flange surfaces are at the same height when each sequence of parts is manufactured, such as Figure 3 shown.

[0028] A guide structure 7 is designed between the die and the edge pressing 3, and between the edge pressing 3 and the punch, and the guide structure 7 is a tiger head structure; A positioning structure 6 is designed on the edge clamp 3 for the preforming process. The positioning structure 6 of the device is a positioning pin, which is used to position the blank A in the preforming process; the first-order part B and the second-order part C are respectively positioned by the molding surface on the edge clamp 3. The edge clamp 3 is designed with a take-out groove 4 for the three processes.

[0029] The edge pressing action of this set of molds is realized by the ejector rod of the isothermal hot forming equipment, and an ejector rod hole matching the ejector rod of the equipment is opened in the punch. Figure 4 shown.

[0030] Reference Figure 5-Figure 7 , the forming method is as follows: (1) The ejector pin is raised until the edge holder 3 is completely above the punch; (2) The blank A is manually placed in the pre-forming process cavity on the leftmost side of the press 3 and positioned by the positioning pin; the first-order part B that has completed the pre-forming process is placed in the deep drawing process cavity in the middle of the press 3 and positioned by the molding surface; the second-order part C that has completed the deep drawing process is placed in the punching process cavity on the rightmost side of the press 3 and positioned by the molding surface, and each part is preheated; (3) The die and the edge holder 3 are closed, and the ejector pin is pressurized to a preset tonnage; (4) The die and the edge holder 3 maintain pressure and move downward as a whole until they are completely engaged with the punch and the die cannot move further downward; (5) Maintaining pressure; (6) Return stroke of the die; (7) The ejector pin is raised until the part is separated from the punch, and the part is removed from the removal groove 4 of the pressure edge 3.

[0031] The forming method of the mold can obtain the finished product of three processes, and the parts can be placed in the next process during the next molding, which saves time.

[0032] The progressive die of the present invention adopts a one-mold multi-process cavity design, replacing a single-process single-set mold design, and realizes multi-process forming in one molding. While reducing the mold cost, it greatly improves the use efficiency of the hot forming equipment, shortens the development cycle of parts and reduces the part development cost.

[0033] The above is a detailed introduction to the design method of an isothermal hot forming progressive die provided by the present invention. This article uses specific examples to illustrate the structure and working principle of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A design method for an isothermal hot forming progressive die, characterized in that: It includes a progressive die, which is provided with a variety of cavities, each cavity corresponds to a different process, and a plurality of processes can be formed simultaneously in one molding process.

2. The design method of isothermal hot forming progressive die according to claim 1, characterized in that: The cavity arrangement adopts a symmetrical layout to avoid unbalanced loading of the equipment.

3. The design method of isothermal hot forming progressive die according to claim 1, characterized in that: The edge holding surfaces of all processes in the cavity are of the same height, thus avoiding unbalanced loading of the equipment.

4. An isothermal hot forming progressive die designed by the design method according to any one of claims 1 to 3, characterized in that: From top to bottom, it comprises an upper die (1), a press edge (3) and a lower die (2); a plurality of process cavities are arranged on the press edge (3); a piece removal groove (4) is arranged in each process cavity of the press edge (3); and a push rod hole (5) is arranged on the lower die (2).

5. The isothermal hot forming progressive die according to claim 4, characterized in that: A guide structure (7) is provided between the upper die (1) and the edge pressing (3), and between the lower die (2) and the edge pressing (3).

6. The isothermal hot forming progressive die according to claim 4, characterized in that: The ejector rod hole (5) on the bottom surface of the lower mold (2) matches the ejector rod of the equipment.

7. The isothermal hot forming progressive die according to claim 4, characterized in that: A preform positioning structure (6) designed according to each process step is arranged on the edge pressing (3).

8. A forming method of an isothermal hot forming progressive die according to claim 4, characterized in that: The following steps are included: Step 1: placing each preformed part at a corresponding position of the edge press (3) according to each sequence positioning structure (6) and preheating; Step 2: The upper mold (1) and the edge pressing (3) are molded together; Step 3: The edge pressing (3) is maintained under pressure, and the upper mold (1) and the edge pressing (3) after mold closing move downward as a whole until they are completely closed with the lower mold (2) and the pressure is maintained; Step 4: The upper die (1) returns and the ejector pin rises until the part is separated from the lower die (2) and the part is removed.

9. The isothermal hot forming method of the progressive die according to claim 8, characterized in that: The preformed parts in step 1 include but are not limited to the original blank, the first-order parts obtained after the original blank undergoes a first process, and the second-order parts obtained after the first-order parts undergo a second process.

10. The isothermal hot forming method of a progressive die according to claim 8, characterized in that: The forming process is carried out at a constant temperature.

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