Titanium alloy strip plate part electric field auxiliary forming method and device

Abstract

The invention provides an electric field auxiliary forming method and device for a titanium alloy strip plate part. The forming device is composed of a direct-current power source, an upper die plate, a lower die base, an upper insulating plate, a lower insulating plate, a male die, a female die, a left guide column, a left guide sleeve, a right guide column, a right guide sleeve, a left supporting frame, a right supporting frame, a left cover plate, a right cover plate, a left insulating block, a right insulating block, a first baffle and a second baffle. In the forming method, the electric field acts on the forming process of the plate, so that the deformation resistance in the forming process of the plate is reduced, and the forming performance of the material is improved; the defects of wrinkling, springback and the like in the forming process of the large thin-wall part are reduced by utilizing the effect of current in the electric field auxiliary forming process, and the forming precision is improved; the gap is reserved between the flanging forming sides of the male die and the female die, so that accumulation of materials at the flanging structure is reduced, and the defects of wrinkling and cracking of strip plate parts are reduced; the heating device for high-temperature forming of the large thin-wall component is simplified, and the size and the cost of the heating device are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of metal plastic processing and forming, and in particular to an electric field assisted forming method and device for titanium alloy strip plate parts. Background Art

[0002] Titanium alloys have been widely used in aerospace, shipbuilding, medical and other fields due to their high specific strength, high temperature resistance, and corrosion resistance. Titanium alloy strip parts, as a large thin-walled component, are used in important parts such as aircraft wings, fuselages, and liquid rocket engine thrust chambers. However, titanium alloys have poor plasticity at room temperature, and are prone to insufficient forming performance or fracture during processing. In addition, the overall size of strip parts is large, and the rebound phenomenon after forming is also a problem that needs to be solved urgently.

[0003] Electric field assisted forming is to introduce electric current on the basis of cold forming, and use the electroplastic effect and Joule heating effect of electric current to improve the forming performance of titanium alloy. Due to the large size of strip parts, conventional hot forming methods not only have long heating time and high energy consumption, but the required heating device also needs to consider vacuum and other issues, and the heating device is complex. In addition, the introduction of electric current on the basis of traditional cold forming process can not only achieve rapid heating of materials and solve the problems of high energy consumption and long cycle of conventional high-temperature forming, but also effectively reduce the deformation resistance of materials, improve the forming performance of materials, improve the forming accuracy and efficiency of parts, and effectively avoid problems such as wrinkling and springback. Summary of the invention

[0004] The present invention aims to solve the technical problems of long heating time, high energy consumption, large springback and poor forming precision of existing large-scale thin-walled titanium alloy strip plate parts, and proposes an electric field assisted forming method and device for titanium alloy strip plate parts.

[0005] The electric field assisted forming device for titanium alloy strip parts of the present invention comprises a direct current power supply (1), an upper mold plate (2), a lower mold base (3), an upper insulating plate (4), a lower insulating plate (5), a punch (6), a die (7), a left guide post (8), a left guide sleeve (9), a right guide post (10), a right guide sleeve (11), a left support frame (12), a right support frame (13), a left cover plate (14), a right cover plate (15), a left insulating block (16), a right insulating block (17), a first baffle plate (18), and a second baffle plate (19).

[0006] The upper template (2) is processed with a threaded hole with a countersunk hole and two guide column holes. The upper template (2) is connected to a circular flange-type die handle by bolts and fixed on a punching machine.

[0007] The male mold (6) and the female mold (7) are curved surface features of the plate-bearing part, and the bottom is connected to the insulating plate and the template die seat by threads. The upper insulating plate (4) is installed between the male mold (6) and the upper template (2), and the lower insulating plate (5) is installed between the female mold (7) and the lower die seat (3). The side surfaces of the male mold (6) and the female mold (7) are processed with a first baffle positioning groove; and the curved forming surface side of the female mold is additionally processed with a sheet metal positioning groove.

[0008] The first baffle (18) and the second baffle (19) are installed on both sides of the male and female dies. The first baffle is a rectangular plate with rounded corners at one end and is threadedly fixed in the first baffle positioning groove of the male die (6). The second baffle is an irregular plate-shaped structure and is threadedly fixed on the other side of the female die (7).

[0009] The left guide pin (8), left guide sleeve (9) and right guide pin (10), right guide sleeve (11) are oil-lubricated guide pins and sleeves with positioning holes. The left guide pin (8) and the right guide pin (10) are installed on the lower die base (3) through threaded connection, and the left guide sleeve (9) and the right guide sleeve (11) are installed on the upper die plate (2) through threaded connection.

[0010] The left support frame (12) and the right support frame (13) are an integrated structure consisting of a support frame and a support plate. The support frame is an L-shaped metal plate structure. The left support frame (12) is installed on the left side of the lower mold base (3) through a left insulating block (16) by threaded connection, and the right support frame (13) is installed on the right side of the lower mold base (3) through a right insulating block (17) by threaded connection. The support plate is placed flat on the support frame, and a semicircular through hole is processed on the support plate for passing the pulse power supply cable. Platforms are processed at both ends of the semicircular structure, and through holes are processed on the platforms.

[0011] The left cover plate (14) and the right cover plate (15) are semicircular arch structures, with platforms processed at both ends of the semicircular arch structures, through holes processed on the platforms, and connected to the left support frame (12) and the right support frame (13) by bolts and nuts.

[0012] One end of the output end of the DC power supply (1) passes through the circular hole between the left support frame (12) and the left cover plate (14) and is connected to the pin hole at one end of the plate material through bolts and nuts, and the other end passes through the circular hole between the right support frame (13) and the right cover plate (15) and is connected to the pin hole at the other end of the plate material through bolts and nuts.

[0013] In the present invention, the preformed sheet is placed in the sheet positioning groove on the die to achieve positioning. The fixed initial position of the sheet is more conducive to improving the forming accuracy. The first baffle and the second baffle are respectively installed on both sides of the punch and the die by bolts to prevent the sheet from sliding sideways during the forming process.

[0014] The upper insulating plate is fixed between the upper mold plate and the punch, and the upper mold plate, the upper insulating plate and the punch are connected by bolts on the upper side of the upper mold plate. The upper insulating plate is used to prevent the punch and the upper mold plate from conducting electricity. The lower insulating plate is fixed between the lower mold base and the die, and the lower mold base, the lower insulating plate and the die are connected by bolts on the lower side of the lower mold base. The lower insulating plate is used to prevent the die and the lower mold base from conducting electricity.

[0015] The left and right insulating blocks are respectively clamped between the left and right support frames and the concave die, and the left and right support frames and the left and right insulating blocks are fixed to the concave die by bolt connection. The left and right insulating blocks are used to prevent the electrode head at the output end of the DC power supply from being electrically conductive through the left and right support frames and the lower die base, and to separate the left and right support frames from the concave die, so as to facilitate adjustment of the angle of the DC power supply output cable. The distance of the power supply output end can also be adjusted by increasing or decreasing the number of the left and right insulating blocks;

[0016] Since there is a flange structure on one side of the formed strip part, in order to reduce the accumulation of titanium alloy material at the flange structure of the male and female dies during the forming process, a gap will be reserved on one side after the male and female dies are closed to control the material flow and reduce wrinkling defects.

[0017] The present invention connects the positive and negative poles of a DC power supply to the left and right ends of a sheet material to form a closed loop and pass a DC current to achieve self-resistance heating of the sheet material. Passing current can utilize the "Joule heating effect" of the current to achieve rapid self-resistance heating of the sheet material and improve the heating efficiency of the sheet material, and can also utilize the "electroplastic effect" of the current to improve the forming performance of the material and reduce the deformation resistance.

[0018] The method for using the electric field assisted forming device for titanium alloy strip plate parts of the present invention is as follows:

[0019] 1. Apply lubricating oil to the left guide sleeve and the right guide sleeve; place the processed titanium alloy plate in the positioning groove of the concave mold plate; connect the left and right support frames and the left and right insulating blocks together through bolts, and the insulating blocks are clamped between the support frames and the lower die base; pass the pulse power supply output end cable through the grooves on the left and right support frames, and fasten the output end electrode to the pin holes on both sides of the plate through bolts; fix the left and right cover plates to the left and right support frames respectively through bolts to prevent the cables from slipping;

[0020] 2. Start the DC power supply, use the DC power supply to heat the sheet to be formed, and use the infrared thermometer to monitor the temperature of the sheet in real time; the voltage of the DC power supply is continuously adjustable from 0 to 24V, and the current is continuously adjustable from 0 to 2000A;

[0021] 3. When the infrared thermometer detects that the temperature of the sheet forming area reaches about 900°C, the machine tool is controlled to drive the punch to move downward to load and deform the sheet;

[0022] 4. After the punch and die are closed, keep the DC power supply on for heating and the load applied to the die by the machine tool to maintain the pressure; after the forming is completed, turn off the power supply, control the machine tool to drive the punch to move upward, and take out the formed part after the part temperature cools down.

[0023] The beneficial effects of the present invention compared with the prior art are:

[0024] (1) The present invention heats large-sized sheets of large thin-walled plate parts by direct current, which greatly reduces the heating time and heating energy consumption. Due to the short heating and cooling time, it not only solves the problems of material surface oxidation and coarse grains under conventional high-temperature forming conditions, but also realizes rapid forming, and can form multiple parts in a short time;

[0025] (2) The present invention reduces the deformation resistance during the sheet forming process by applying an electric field to the sheet forming process, thereby improving the forming performance of the material;

[0026] (3) The present invention utilizes the effect of electric current in the electric field-assisted forming process to reduce defects such as wrinkling and springback during the forming process of large thin-walled parts, thereby improving the forming accuracy;

[0027] (4) The present invention reduces the accumulation of materials at the flange structure by leaving a gap between the flange forming sides of the male and female dies, thereby reducing the wrinkling and cracking defects of the plate parts;

[0028] (5) The present invention simplifies the heating device for high-temperature forming of large thin-walled components, reduces the size and cost of the heating device, and is an efficient, low-cost, green forming device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the forming device of the present invention.

[0030] Figure 2 It is an isometric view of the device of the present invention.

[0031] Figure 3a , Figure 3b It is a schematic diagram of the plate parts and the plate material of the forming device of the present invention.

[0032] Figure 4 This is a detailed diagram of the sheet metal positioning of the forming device of the present invention.

[0033] Figure 5 It is a schematic diagram of the second baffle of the forming device of the present invention.

[0034] Figure 6 This is a detailed diagram of the insulation treatment of the forming device of the present invention.

[0035] Figure 7 It is a side view schematic diagram of the male and female molds of the forming device of the present invention after the mold is closed.

[0036] The numbers in the figure are explained as follows:

[0037] 1-DC power supply; 2-upper mold plate; 3-lower mold base; 4-upper insulating plate; 5-lower insulating plate; 6-punch; 7-die; 8-left guide post; 9-left guide sleeve; 10-right guide post; 11-right guide sleeve; 12-left support frame; 13-right support frame; 14-left cover plate; 15-right cover plate; 16-left insulating block; 17-right insulating block; 18-first baffle; 19-second baffle. DETAILED DESCRIPTION

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art 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 expending any novel work.

[0039] like Figure 1-2 As shown, the blank used in the forming process of the present invention is a plate with pin holes at both ends, and the forming device is composed of a DC power supply, an upper template, a lower die base, an upper insulating plate, a lower insulating plate, a punch, a die, a left guide post, a left guide sleeve, a right guide post, a right guide sleeve, a left support frame, a right support frame, a left cover plate, a right cover plate, a left insulating block, a right insulating block, a first baffle plate, and a second baffle plate;

[0040] As shown in FIG3 , the strip part formed by the present invention is a large titanium alloy curvature component, the curved surface length is more than 1m, there is a "Z"-shaped sawtooth feature on the curved surface, and one side has a small flange structure. The forming blank used is a rectangular blank with pin holes at both ends. In order to reduce cracking defects during the forming process, part of the sheet material is cut off on the flange side;

[0041] like Figure 4-5 As shown, the sheet metal positioning method in the forming process of the present invention is to install a first baffle and a second baffle on the male die and the female die respectively, which are installed on both sides of the sheet metal to prevent the sheet metal from sliding sideways during the forming process, and a sheet metal positioning groove is processed on the upper surface of the female die to facilitate the initial positioning of the sheet metal;

[0042] like Figure 6 As shown, the insulation method in the forming process of the present invention is to install an upper insulating plate between the male die and the upper mold plate, a lower insulating plate between the female die and the lower mold plate, a left insulating block between the female die and the left support frame, and a right insulating block between the female die and the right support frame to prevent the current from being introduced into the punch during the power-on process;

[0043] like Figure 7As shown, the forming device of the present invention leaves a gap between the flange forming sides of the male and female dies, which reduces the accumulation of materials at the flange structure and reduces the wrinkling and cracking defects of the strip plate parts;

[0044] The upper die plate is processed with a threaded hole with a countersunk hole and two guide post holes, and the upper die plate is connected to a circular flange die handle by bolts and fixed on the punch press;

[0045] The male and female dies are curved surface features of the plate-bearing parts, the bottom is connected to the insulating plate and the template die seat by threads, the upper insulating plate is installed between the male and the upper template, and the lower insulating plate is installed between the female and the lower die seat, and the side surfaces of the male and female dies are processed with first baffle positioning grooves; the forming surface side of the female die is additionally processed with a sheet metal positioning groove;

[0046] The first baffle and the second baffle are installed on both sides of the male and female molds. The first baffle is a rectangular plate with rounded corners at one end, which is threadedly fixed in the positioning groove of the first baffle of the male mold. The second baffle is an irregular plate-shaped structure, which is threadedly fixed on the other side of the female mold.

[0047] The left guide pin, left guide sleeve and right guide pin, right guide sleeve are oil-lubricated guide pins and sleeves with positioning holes. The left guide pin and the right guide pin are installed on the lower die base through threaded connection, and the left guide sleeve and the right guide sleeve are installed on the upper die plate through threaded connection;

[0048] The left support frame and the right support frame are an integrated structure consisting of a support frame and a support plate. The support frame is an L-shaped metal plate structure. The left support frame and the left insulating block are installed on the lower mold base through a threaded connection. The support plate is placed flat on the support frame. The support plate is processed with semicircular through holes for passing the pulse power supply cable. Platforms are processed at both ends of the semicircular structure, and through holes are processed on the platforms.

[0049] The left cover plate and the right cover plate are semicircular arch structures, with platforms processed at both ends of the semicircular arch structure, through holes processed on the platforms, and connected to the left support frame and the right support frame by bolts and nuts;

[0050] One end of the output end of the DC power supply passes through the circular hole between the left support frame and the left cover plate and is connected to the pin hole at one end of the sheet material through bolts and nuts, and the other end passes through the circular hole between the right support frame and the right cover plate and is connected to the pin hole at the other end of the sheet material through bolts and nuts.

[0051] The material of the male and female dies is 45 steel.

[0052] The material of the first and second baffles is Q235.

[0053] The material of the left support frame, the right support frame, the left cover plate and the right cover plate is Q235.

[0054] The upper and lower insulating plates and the left and right insulating blocks are made of bakelite.

[0055] The method for using the electric field assisted forming device for titanium alloy strip plate parts of the present invention is as follows:

[0056] 1. Apply lubricating oil to the left guide sleeve and the right guide sleeve; place the processed titanium alloy plate in the positioning groove of the concave mold plate; connect the left and right support frames and the left and right insulating blocks together through bolts, and the insulating blocks are clamped between the support frames and the lower die base; pass the pulse power supply output end cable through the grooves on the left and right support frames, and fasten the output end electrode to the pin holes on both sides of the plate through bolts; fix the left and right cover plates to the left and right support frames respectively through bolts to prevent the cables from slipping;

[0057] 2. Start the DC power supply, use the DC power supply to heat the sheet to be formed, and use the infrared thermometer to monitor the temperature of the sheet in real time; the voltage of the DC power supply is continuously adjustable from 0 to 24V, and the current is continuously adjustable from 0 to 2000A;

[0058] 3. When the infrared thermometer detects that the temperature of the sheet forming area reaches about 900°C, the machine tool is controlled to drive the punch to move downward to load and deform the sheet;

[0059] 4. After the punch and die are closed, keep the DC power supply on for heating and the load applied to the die by the machine tool to maintain the pressure; after the forming is completed, turn off the power supply, control the machine tool to drive the punch to move upward, and take out the formed part after the part temperature cools down.

[0060] The sheet material is a TA grade titanium alloy sheet material, and before being placed on the die, a boron nitride anti-oxidation coating needs to be sprayed on its surface, and a high-temperature resistant black paint needs to be sprayed on the middle area of ​​the sheet material for easy temperature measurement.

[0061] Taking titanium alloy sheet as an example, the sheet size is 1050mm×150mm, the thickness is 1.5mm, and the sheet processing is Figure 3bAs shown in the schematic diagram, before forming, the left and right support frames and the left and right sliders are installed, and the boron nitride anti-oxidation coating is sprayed on the punch, die and sheet. After the coating is formed, the processed titanium alloy sheet is placed in the sheet positioning groove on the die, and a layer of insulation cloth is placed on the bottom of the sheet. The pulse power output cable is passed through the grooves on the left and right support frames, and the output electrode is connected to both sides of the sheet, and high-temperature resistant black paint is sprayed on the center area of ​​the sheet. The DC power supply is started to heat the sheet. During the heating process of the sheet, the infrared thermometer is used to measure the temperature in real time. When the temperature is stable at about 900℃, the machine tool is controlled to move and drive the punch downward to load and deform the sheet. When the punch moves to form some reinforcement ribs but does not form the "Z" shape feature, the machine tool is stopped and the machine tool is controlled to drive the punch upward. After the temperature of the sheet is stable, the machine tool continues to control the movement of the punch downward until the punch and die are closed. The purpose of forming in two stages is to maintain the temperature and reduce rebound. After the punch and the die are closed, the DC power supply is kept on for heating and the machine tool applies a load to the die, and the pressure is maintained for 1 minute. After the forming is completed, the power is turned off, and the machine tool is controlled to drive the punch to move upward. After the temperature of the part cools down, the formed part is taken out, the surface is cleaned and the edges are trimmed.

Claims

1. A titanium alloy strip plate part electric field assisted forming device, characterized in that: The invention is composed of a direct current power supply (1), an upper mold plate (2), a lower mold base (3), an upper insulating plate (4), a lower insulating plate (5), a punch (6), a die (7), a left guide post (8), a left guide sleeve (9), a right guide post (10), a right guide sleeve (11), a left support frame (12), a right support frame (13), a left cover plate (14), a right cover plate (15), a left insulating block (16), a right insulating block (17), a first baffle plate (18), and a second baffle plate (19); wherein: The upper template (2) is processed with a threaded hole with a countersunk hole and two guide post holes. The upper template (2) is connected to a circular flange-type die handle by bolts and fixed on the punching machine. The male mold (6) and the female mold (7) are curved surface features of the plate-bearing part, the bottom is connected to the insulating plate and the template die seat by threads, the upper insulating plate (4) is installed between the male mold (6) and the upper template (2), the lower insulating plate (5) is installed between the female mold (7) and the lower die seat (3), and the side surfaces of the male mold (6) and the female mold (7) are processed with a first baffle positioning groove; The first baffle (18) and the second baffle (19) are installed on both sides of the male and female molds. The first baffle is a rectangular plate with rounded corners at one end and is threadedly fixed in the first baffle positioning groove of the male mold (6). The second baffle is an irregular plate-shaped structure and is threadedly fixed on the other side of the female mold (7). The left guide pin (8), the left guide sleeve (9), the right guide pin (10), and the right guide sleeve (11) are oil-lubricated guide pins and sleeves with positioning holes. The left guide pin (8) and the right guide pin (10) are installed on the lower die base (3) through threaded connection, and the left guide sleeve (9) and the right guide sleeve (11) are installed on the upper die plate (2) through threaded connection. The left support frame (12) and the right support frame (13) are an integrated structure consisting of a support frame and a support plate. The support frame is an L-shaped metal plate structure. The left support frame (12) is installed on the left side of the lower mold base (3) through a left insulating block (16) by threaded connection. The right support frame (13) is installed on the right side of the lower mold base (3) through a right insulating block (17) by threaded connection. The support plate is placed flat on the support frame. A semicircular through hole is processed on the support plate for passing the pulse power supply cable. Platforms are processed at both ends of the semicircular structure, and through holes are processed on the platform. The left cover plate (14) and the right cover plate (15) are semicircular arch structures, with platforms processed at both ends of the semicircular arch structures, through holes processed on the platforms, and connected to the left support frame (12) and the right support frame (13) by bolts and nuts; One end of the output end of the DC power supply (1) passes through the circular hole between the left support frame (12) and the left cover plate (14) and is connected to the pin hole at one end of the plate material through bolts and nuts, and the other end passes through the circular hole between the right support frame (13) and the right cover plate (15) and is connected to the pin hole at the other end of the plate material through bolts and nuts.

2. The electric field assisted forming device for titanium alloy strip parts according to claim 1 is characterized in that: The curved forming surface side of the die is additionally processed with a sheet metal positioning groove; the preformed sheet metal is placed in the sheet metal positioning groove on the die to achieve positioning.

3. The electric field assisted forming device for titanium alloy strip parts according to claim 1 is characterized in that: There is a flange structure on one side of the formed strip part. In order to reduce the accumulation of titanium alloy material at the flange structure of the male and female dies during the forming process, a gap will be reserved on one side after the male and female dies are closed to control the material flow and reduce wrinkling.

4. The electric field assisted forming device for titanium alloy strip parts according to claim 1 is characterized in that: The positive and negative poles of the DC power supply are fixedly connected to the left and right ends of the plate to form a closed loop and pass DC current to achieve self-resistance heating of the plate.

5. The electric field assisted forming device for titanium alloy strip parts according to claim 1 is characterized in that: The material of the male and female dies is 45 steel.

6. The electric field assisted forming device for titanium alloy strip parts according to claim 1 is characterized in that: The material of the first and second baffles is Q235.

7. The electric field assisted forming device for titanium alloy strip parts according to claim 1 is characterized in that: The material of the left support frame, the right support frame, the left cover plate and the right cover plate is Q235.

8. The electric field assisted forming device for titanium alloy strip parts according to claim 1 is characterized in that: The upper and lower insulating plates and the left and right insulating blocks are made of bakelite.

9. A method for using the electric field assisted forming device for titanium alloy strip parts according to any one of claims 1 to 9 is as follows: Step 1. Apply lubricating oil to the left guide sleeve and the right guide sleeve; place the processed titanium alloy plate in the positioning groove of the concave mold plate; connect the left and right support frames and the left and right insulating blocks together through bolts, and the insulating blocks are clamped between the support frames and the lower mold base; respectively pass the pulse power supply output end cable through the grooves on the left and right support frames, and the output end electrode and the pin holes on both sides of the sheet material are fastened together through bolts; respectively fix the left and right cover plates to the left and right support frames through bolts to prevent the cables from slipping; Step 2: Start the DC power supply, use the DC power supply to heat the sheet to be formed, and use an infrared thermometer to monitor the temperature of the sheet in real time; the voltage of the DC power supply is continuously adjustable from 0 to 24V, and the current is continuously adjustable from 0 to 2000A; Step 3: When the infrared thermometer detects that the temperature of the sheet forming area reaches 900°C, the machine tool is controlled to drive the punch to move downward to load and deform the sheet; Step 4: After the punch and die are closed, keep the DC power supply on for heating and the load applied to the die by the machine tool to maintain the pressure; after the forming is completed, turn off the power supply, control the machine tool to drive the punch to move upward, and take out the formed part after the part temperature cools down.

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