An electrically assisted progressive bulging device and method for large-size thin-walled pipes of difficult-to-deform alloys

Abstract

The present invention discloses an electrically assisted progressive bulging device and method for large-size thin-walled pipes of difficult-to-deform alloys. The electrically assisted progressive bulging device mainly includes a mold, an electrically assisted heating component, a punch, a central axis, an electrode adjustment mechanism, and a control device, and the device is relatively simple. The electrically assisted progressive bulging device and method make full use of the existing progressive forming technology, and combine the characteristics of hot bulging forming of workpieces to develop a local gas bulging forming technology. Through the processing mode from local forming to overall forming, a constant gas pressure is passed through the closed pipe, and a combination of local electrically assisted heating and continuous micro-bulging technology is used to complete the forming process of workpieces with complex surface shapes, which has the advantages of precise temperature control and high forming accuracy. The wall thickness of the bulging area of ​​the formed part is uniform, the degree of film adhesion is high, and the surface accuracy and various performances are good.

Description

Technical Field

[0001] The invention relates to an electrically assisted progressive bulging device and a method for a large-size thin-walled pipe of a difficult-to-deform alloy, and belongs to the technical field of material forming. Background Art

[0002] Large-sized tubular thin-walled parts play an important role in the aerospace field, such as the air intake and tail nozzle of aircraft engines. However, these parts are large in size in most cases. For example, the maximum diameter of the tail nozzle of an aircraft engine is about one meter, and some even reach two or three meters. The surface shape is complex and the material is difficult to process metal. If welding is used, although it can be formed, when these aircraft, especially hypersonic aircraft, fly, due to the high flight speed, the parts and the air rub violently, causing the temperature of the parts to rise sharply. The performance of the weld is poor, and it is very easy to burn and fail at high temperatures, leading to extremely serious consequences. Therefore, for these large-sized difficult-to-deform closed pipes used in the aerospace field, an integral forming method should be adopted, and inflation is the most widely used in integral forming. However, the hard-to-deform metal materials commonly used in the field of aerospace manufacturing, such as titanium alloys, intermetallic compounds, and high-strength aluminum alloys, often have the characteristics of low elastic modulus and high specific strength, which leads to the disadvantages of high forming pressure, difficulty in plastic deformation, and obvious springback during overall forming. In addition, the microstructure in the raw materials may be changed or destroyed, thereby deteriorating the performance of the formed parts. Therefore, it is necessary to propose a large-size thin-walled pipe forming method that can overcome the problems of hard-to-deform metal materials being difficult to deform, high forming pressure, and poor forming quality.

[0003] Regarding the forming method of large-size thin-walled pipe fittings of difficult-to-deform alloys, there are also some technical solutions for the inflation forming of pipe fittings in the existing technology.

[0004] A Chinese patent with application number CN108655250B discloses a method for hot forming of pipe fittings by inflation, and the forming method includes "taking the pipe fittings to be formed and placing the pipe fittings into the upper end of the lower die; controlling the upper and lower dies to close, controlling the end cap and the forming module to position the pipe fittings, and spraying fuel on the forming module; heating and melting the pipe fittings through the forming module, the upper die and the lower die, and forming the pipe fittings with the forming module in cooperation with the upper die and the lower die." This technical solution is to heat and pressurize the pipe fittings by spraying fuel and heating and melting. This method is difficult to accurately control the heating temperature of the pipe fittings and the air pressure in the pipe. Moreover, under such extremely unstable temperature and air pressure conditions, the forming accuracy, surface quality and wall thickness uniformity of the pipe fittings are poor when the pipe fittings are formed once. In addition, this forming method is difficult to process large-sized pipe fittings.

[0005] A Chinese patent with application number CN201010228426 discloses a composite forming method of air bulging and hot forming and the device used therein, including "pre-bending and welding the raw material into a conical cylinder; placing the lower end of the airbag in the lower slot of the airbag; placing the raw material sleeve on the outer surface of the hot forming mold; placing the mold cover above the air bulging mold; hoisting the tooling parts onto the workbench of the air bulging furnace, and connecting the airbag with the external ventilation pipeline, closing the furnace door, and starting the heating device; performing hot forming; when the air bulging forming temperature is reached, air bulging is performed according to the air bulging forming process; after the tooling parts are cooled, the tooling parts are taken out; and the parts are disassembled in the reverse order of assembling the tooling parts." Although the technical solution of this patent is suitable for the bulging of large-scale tubular thin-walled parts, it requires pre-bending, welding, heating of the tooling parts as a whole, and one-time forming, so the various properties, workpiece quality and forming accuracy of the formed parts are difficult to guarantee. Moreover, the thermal expansion equipment required for this technical solution is large and energy-intensive, making it difficult to apply and promote in practice. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a method for local continuous heating and local continuous inflation forming. The core of the method is to make full use of the existing progressive forming technology, combine the characteristics of workpiece hot inflation forming, and develop a local inflation forming technology. Through the processing mode from local forming to overall forming, a constant air pressure is passed into the closed pipe, and a combination of local electric auxiliary heating and continuous micro-inflation technology is used to complete the forming process of workpieces with complex surface shapes, which has the advantages of precise temperature control and high forming accuracy.

[0007] In order to achieve the above technical objectives, the present invention will adopt the following technical solutions:

[0008] A method for electrically assisted progressive bulging of large-sized thin-walled pipes made of difficult-to-deform alloys. The method combines the incremental forming process with electrically assisted pneumatic bulging technology, discretizes the large-sized thin-walled pipes into several areas, and plans the processing paths based on the characteristics of these areas. The mobile electrically assisted heating component heats each area in turn, and the heated pipe material is pneumatically bulged under the action of internal air pressure.

[0009] Another technical purpose of the present invention is to provide an electrically assisted progressive bulging device for large-size thin-walled pipes of difficult-to-deform alloys, characterized in that it includes a die, an electrically assisted heating assembly, a punch, a central axis, an electrode positioning mechanism, and a control device; wherein:

[0010] The mold is provided with a forming cavity; the thin-walled pipe to be formed is coaxially arranged with the forming cavity;

[0011] The central axis is arranged along the axis of the forming cavity;

[0012] The punches described above have two punches, punch a1 and punch b1; the two ends of the thin-walled tube to be formed are sealed by punch a1 and punch b1 respectively; the inside of the tube cavity of the thin-walled tube to be formed with both ends sealed is preset with a gas with a pressure of P0;

[0013] The electric auxiliary heating components include two components, namely, electric auxiliary heating component a2 and electric auxiliary heating component b2, each of which includes an annular pure copper block, a carbon brush, a wire, and an electrode. The electrode can contact the inner wall of the thin-walled pipe to be formed, and the electrode is connected to the carbon brush fixed on the annular pure copper block through the wire. The annular pure copper block of the electric auxiliary heating component a2 is fixed to the punch a1, and the annular pure copper block of the electric auxiliary heating component b2 is fixed to the punch b1.

[0014] The electrode positioning mechanism is installed on the central axis and has two power output ends, namely, power output end a3 and power output end b3. The power output end a3 of the electrode positioning mechanism is connected to the electrode of the electric auxiliary heating component a2, and the power output end b3 of the electrode positioning mechanism is connected to the electrode of the electric auxiliary heating component b2.

[0015] The electrode positioning mechanism is connected to the control device signal, and can drive the electrodes connected to the power output ends to form the discrete layers of the target surface layer by layer in the radial direction according to the forming process path planned in the control device, so as to manufacture the target surface that meets the requirements layer by layer in the forming process part; and each layer of the to-be-formed area drives the electrodes connected to each other through the two power output ends of the electrode positioning mechanism according to the planning of the forming process path, and heats the to-be-formed sub-areas within the range of the two electrodes in the to-be-formed part one by one, and finally realizes the gas expansion forming of the thin-walled pipe fitting step by step under the action of the gas pressure P0;

[0016] The electrodes of the electric auxiliary heating component a2 and the electrodes of the electric auxiliary heating component b2 can both step and translate along the central axis under the action of the electrode positioning mechanism; at the same time, the electrodes of the electric auxiliary heating component a2 and the electrodes of the electric auxiliary heating component b2 in the energized state can rotate around the central axis under the power output of their respective electrode positioning mechanisms, so as to rotationally heat the sub-region to be formed within the range of the two electrodes of the thin-walled pipe to be formed until the sub-region to be formed reaches a predetermined expansion temperature; the material in this region is expanded under the action of the air pressure P0 to obtain a local air expansion forming surface corresponding to the sub-region to be formed.

[0017] Furthermore, the electrode positioning mechanism includes a rotation drive device for driving the central axis to rotate and a translation mechanism for driving the electrode to translate; the power output end of the rotation drive device is connected to the central axis; the fixed end of the translation mechanism is fixed to the central axis, and the actuating end of the translation mechanism is connected to the electrode.

[0018] Furthermore, the rotary drive device includes a motor, a motor sleeve, and a reduction gear; the motor is built into the tube cavity of the thin-walled pipe to be formed, and the base of the motor is sleeved on the central shaft through the motor sleeve, and the power output end of the motor is connected to the central shaft through the reduction gear.

[0019] Furthermore, the translation mechanism includes a moving disk and a slide rail; a circular disk is coaxially arranged on the central axis, the slide rail is supported by the circular disk, the moving disk is movably mounted on the slide rail, and the electrode is mounted on the moving disk; the carbon brush is supported on the slide rail through an insulating bracket.

[0020] Furthermore, the rotary drive device includes a motor and a coupling; the motor is externally arranged at one end of the thin-walled tube to be formed, and the power output end of the motor is connected to the central axis through the coupling; the translation mechanism includes a movable disk, which is movably mounted on the central axis, and the electrode is mounted on the movable disk, and the end of the electrode can touch the inner wall of the thin-walled tube to be formed; the carbon brush is supported on the central axis through an insulating bracket.

[0021] Furthermore, a compression spring is arranged between the end of the electrode and the movable disk.

[0022] Another technical object of the present invention is to provide an electrically assisted progressive bulging method for a large-size thin-walled pipe of a difficult-to-deform alloy, comprising the following steps:

[0023] (1) According to the characteristics of the pipe to be processed, the target surface of the thin-walled pipe is discretized into a number of to-be-formed regions along the radial direction, and then each to-be-formed region is discretized into a number of to-be-formed sub-regions along the axial direction of the thin-walled pipe, and a forming path is planned according to the to-be-formed sub-regions.

[0024] (2) After the components built into the thin-walled pipe to be formed are assembled, they are assembled into the inner cavity of the thin-walled pipe to be formed, and then the two sides of the thin-walled pipe to be formed are sealed with a punch, and a predetermined air pressure of P0 (P0 is less than the plastic deformation yield pressure P of the pipe at room temperature) is introduced. S室 , greater than the plastic deformation yield pressure P of the pipe at high temperature T ST ) gas, and finally installing the mold at the position corresponding to the thin-walled pipe to be formed;

[0025] (3) Move the two electrodes to the right starting end of the thin-walled tube to be formed, maintain a certain distance d, then power the equipment, the two electrodes start to rotate, and rotate and heat the small section of the energized section within the range of the two electrodes;

[0026] (4) When the temperature monitoring device inside the equipment detects that the temperature of the energized small section reaches the predetermined bulging temperature, the electrode and the motor are powered off, and the heated energized small section begins to bulge under the action of the air pressure P0, and the left punch moves to the right to achieve a small amount of material filling during the bulging process until the bulging of the first section of the sub-area to be formed is completed;

[0027] (5) After the heating and bulging of the first sub-region to be formed is completed, the two electrodes are moved to the left by a step distance d1 equal to d, and the electrodes are powered again to rotate and heat the small section of the energized section within the range of the two electrodes, and the bulging of the second sub-region to be formed is completed in the manner of step 4;

[0028] (6) When the bulging of the second sub-region to be formed is completed, step 4 is repeated until the bulging of the last sub-region to be formed of the first layer is completed;

[0029] (7) After the bulging work of the first layer of the area to be formed is completed, the two electrodes are withdrawn to the right starting end of the thin-walled tube to be formed, and steps 3-6 are repeated until the bulging work of the last layer of the area to be formed of the thin-walled tube to be formed is completed, and the tube bulging is terminated.

[0030] According to the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention makes full use of the existing progressive forming technology, combines the characteristics of workpiece hot expansion forming, and develops a local gas expansion forming technology. Through the processing mode from local forming to overall forming, a constant gas pressure is passed into the closed pipe, and a combination of local electric auxiliary heating and continuous micro-expansion technology is used to complete the forming of workpieces with complex surface shapes. It has the advantages of precise temperature control and high forming accuracy. The wall thickness of the bulging area of ​​the formed part is uniform, the degree of film adhesion is high, and the surface accuracy and various performances are good. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the principle of the electric-assisted progressive bulging method of the present invention;

[0033] Figure 2 It is a schematic diagram of the process of the electric-assisted progressive bulging method of the present invention;

[0034] Figure 3 It is a schematic diagram of the electric-assisted progressive bulging device described in Example 1 of the present invention;

[0035] Figure 4 It is a schematic diagram of the electric-assisted progressive bulging device described in Example 2 of the present invention;

[0036] Figure 5 It is a schematic diagram of the electric-assisted progressive bulging device described in Example 3 of the present invention;

[0037] In the figure: reduction gear 1; motor sleeve 2; motor 3; central shaft 4; disc 5; slide rail structure 6; moving disc 7; insulating block 8; compression spring 9; electrode 10; wire 11; insulating bracket 12; carbon brush 13; annular pure copper block 14; punch 15; thin-walled pipe fitting 16; mold 17. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise specified, the relative arrangement, expressions and numerical values ​​of the components and steps described in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and devices known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and devices should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0039] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations).

[0040] In view of the difficulties existing in the forming process of existing large-size thin-walled pipe fittings, the present invention innovatively develops a forming method that combines incremental forming technology and local bulging technology, making full use of the advantages of incremental forming technology and gas bulging forming technology, so that the formed workpiece has the advantages of good processing accuracy and surface quality, high forming limit, etc., and also has the advantages of low tool cost, short heating time, and no need for specific molds.

[0041] In order to realize the above-mentioned electric-assisted progressive bulging method, the present invention discloses an electric-assisted progressive bulging device for large-size thin-walled pipes of difficult-to-deform alloys, comprising a die, an electric-assisted heating assembly, a punch, a central axis, an electrode positioning mechanism, and a control device; wherein:

[0042] The mold is provided with a forming cavity;

[0043] The thin-walled pipe to be formed is coaxially arranged in the forming cavity;

[0044] The central axis is arranged along the axis of the forming cavity;

[0045] The punches described above have two punches, punch a1 and punch b1; the two ends of the thin-walled pipe to be formed are sealed by punch a1 and punch b1 respectively; the tube cavity of the thin-walled pipe to be formed with sealed ends is preset with gas at a pressure of P0.

[0046] The electric auxiliary heating components include two, namely, electric auxiliary heating component a2 and electric auxiliary heating component b2, each including an annular pure copper block, a carbon brush, a wire, and an electrode. The electrode can contact the inner wall of the thin-walled pipe to be formed, and the electrode is connected to the carbon brush fixed on the annular pure copper block through the wire. The annular pure copper block of the electric auxiliary heating component a2 is fixed to the punch a1, and the annular pure copper block of the electric auxiliary heating component b2 is fixed to the punch b1.

[0047] The electrode positioning mechanism is installed on the central axis and has two power output ends, namely, power output end a3 and power output end b3. The power output end a3 of the electrode positioning mechanism is connected to the electrode of the electric auxiliary heating component a2, and the power output end b3 of the electrode positioning mechanism is connected to the electrode of the electric auxiliary heating component b2.

[0048] The rotary drive device comprises a motor, a motor sleeve, and a reduction gear; the motor is built into the tube cavity of the thin-walled pipe to be formed, and the base of the motor is sleeved on the central shaft through the motor sleeve, and the power output end of the motor is connected to the central shaft through the reduction gear;

[0049] The translation mechanism comprises a moving disk and a slide rail; a circular disk is coaxially arranged on the central axis, the slide rail is supported by the circular disk, the moving disk is movably mounted on the slide rail, and the electrode is mounted on the moving disk;

[0050] The carbon brush is supported on the slide rail through an insulating bracket;

[0051] Alternatively, the rotary drive device includes a motor and a coupling; the motor is externally arranged at one end of the thin-walled pipe to be formed, and the power output end of the motor is connected to the central shaft through the coupling; the translation mechanism includes a movable disk, which is movably mounted on the central shaft, and the electrode is mounted on the movable disk, and the end of the electrode can touch the inner wall of the thin-walled pipe to be formed; the carbon brush is supported on the central shaft through an insulating bracket.

[0052] In the present invention, in order to avoid damage to the electrode tip, a compression spring is arranged between the electrode tip and the moving disk.

[0053] The electrode positioning mechanism is connected to the control device signal, and can drive the electrodes connected to the power output ends to form the discrete layers of the target surface layer by layer in the radial direction according to the forming process path planned in the control device, so as to manufacture the target surface that meets the requirements layer by layer in the forming process part; and each layer of the to-be-formed area drives the electrodes connected to each other through the two power output ends of the electrode positioning mechanism according to the planning of the forming process path, and heats the to-be-formed sub-areas within the range of the two electrodes in the to-be-formed part one by one, and finally realizes the gas expansion forming of the thin-walled pipe fitting step by step under the action of the gas pressure P0;

[0054] The electrodes of the electric-assisted heating component a2 and the electrodes of the electric-assisted heating component b2 can both step and translate along the central axis under the action of the electrode positioning mechanism; at the same time, the electrodes of the electric-assisted heating component a2 and the electrodes of the electric-assisted heating component b2 in the energized state can rotate around the central axis under the power output of their respective electrode positioning mechanisms, so as to rotationally heat the annular sub-region of the thin-walled pipe to be formed within the range of the two electrodes until the annular sub-region reaches a predetermined expansion temperature; the annular sub-region that reaches the predetermined expansion temperature expands under the action of the air pressure P0 to obtain an annular local air-expanding forming surface corresponding to the annular sub-region.

[0055] According to the above-mentioned electric-assisted progressive bulging device, the present invention provides an electric-assisted progressive bulging method, comprising the following steps:

[0056] (1) According to the characteristics of the pipe to be processed, the target surface of the thin-walled pipe is discretized into a number of to-be-formed regions along the radial direction, and then each to-be-formed region is discretized into a number of to-be-formed sub-regions along the axial direction of the thin-walled pipe, and a forming path is planned according to the to-be-formed sub-regions.

[0057] (2) After the components built into the thin-walled pipe to be formed are assembled, they are assembled into the inner cavity of the thin-walled pipe to be formed, and then the two sides of the thin-walled pipe to be formed are sealed with a punch, and a predetermined air pressure of P0 (P0 is less than the plastic deformation yield pressure P of the pipe at room temperature) is introduced. S室 , greater than the plastic deformation yield pressure P of the pipe at high temperature T ST) gas, and finally installing the mold at the position corresponding to the thin-walled pipe to be formed;

[0058] (3) Move the two electrodes to the right starting end of the thin-walled tube to be formed, maintain a certain distance d, then power the equipment, the two electrodes start to rotate, and rotate and heat the small section of the energized section within the range of the two electrodes;

[0059] (4) When the temperature monitoring device inside the equipment detects that the temperature of the energized small section reaches the predetermined bulging temperature, the electrode and the motor are powered off, and the heated energized small section begins to bulge under the action of the air pressure P0, and the left punch moves to the right to achieve a small amount of material filling during the bulging process until the bulging of the first section of the sub-area to be formed is completed;

[0060] (5) After the heating and bulging of the first sub-region to be formed is completed, the two electrodes are moved to the left by a step distance d1 equal to d, and the electrodes are powered again to rotate and heat the small section of the energized section within the range of the two electrodes, and the bulging of the second sub-region to be formed is completed in the manner of step 4;

[0061] (6) When the bulging of the second sub-region to be formed is completed, step 4 is repeated until the bulging of the last sub-region to be formed of the first layer is completed;

[0062] (7) After the bulging work of the first layer of the area to be formed is completed, the two electrodes are withdrawn to the right starting end of the thin-walled tube to be formed, and steps 3-6 are repeated until the bulging work of the last layer of the area to be formed of the thin-walled tube to be formed is completed, and the tube bulging is terminated.

[0063] The electric-assisted progressive bulging device of the present invention will be described in detail below with reference to the accompanying drawings.

[0064] Embodiment 1:

[0065] like Figure 3 As shown, the electric-assisted progressive bulging device for large-size thin-walled pipes of difficult-to-deform alloys described in this embodiment includes a pair of motor sleeves 2, a motor 3, a pair of reduction gears 1, a central shaft 4, two discs 5, a set of slide rail structures 6, two insulating brackets 12, two moving discs 7, two insulating blocks 8, two compression springs 9, two electrodes 10, two wires 11, two carbon brushes 13, two annular pure copper blocks 14, two punches 15, a thin-walled workpiece 16 and a mold 17, etc.

[0066] The motor sleeve 2 and the disc 5 are mounted on the central shaft 4, the motor 3 is mounted in the motor sleeve 2, the reduction gear is mounted on the central shaft 4 and the rotating shaft of the motor 3, the disc 5 is mounted with a slide rail 6, the movable disc 7, the insulating block 8, the compression spring 9, the electrode 10 and the insulating bracket 12 are mounted on the slide rail, the punch 15 is mounted with an annular pure copper block 14, the carbon brush 13 connects the insulating bracket 12 and the annular pure copper block 14, and the wire 11 connects the electrode 10 and the carbon brush 13.

[0067] The electric-assisted progressive bulging device described in this embodiment can be used to obtain an electric-assisted progressive bulging method for large-size thin-walled pipes of difficult-to-deform alloys. The specific operation is as follows: Figure 1 , Figure 2 Schematic diagram implementation, the steps are as follows:

[0068] Step 1: Install large-size pipes, bulging devices and molds and introduce constant air pressure

[0069] After the bulging device is installed as described above, it is placed inside the large-size pipe, the cross-section workpiece 16 and the bulging device are sealed with two punches 15 and corresponding seals, a predetermined constant air pressure P0 is introduced into the pipe, and the mold 17 is installed at the corresponding position of the pipe;

[0070] Step 2: Electrode adjustment and equipment power on

[0071] Before the device is powered on for rotation and heating, the two electrodes 10 are moved to the right starting end of the section to be expanded and kept at a certain distance. Then the device is powered on, and the internal device drives the two electrodes 10 to rotate, and the small section of the annular section between the two electrodes 10 is heated. Figure 1 As shown in the schematic diagram;

[0072] Step 3: Disconnect the electrode and refill the device

[0073] When the temperature of the heated section rises to a predetermined value, the two electrodes 10 and the device motor 3 are powered off, so that the device stops rotating and heating. Since the device passes the calculated bulging air pressure P0, the small section section that has been heated will begin to bulge. After the bulging is completed, the left punch 15 moves to the right to slightly squeeze the section, so as to achieve a slight amount of material supplementation during the bulging process, thereby improving the wall thickness reduction phenomenon.

[0074] Step 4: Adjust the electrodes and power on again

[0075] After the heating and bulging of the first section of the cross section in step 3 is completed, the two electrodes 10 are moved to the left by one step, and then the electrodes 10 and the motor 3 are powered again, so that the two electrodes 10 rotate and heat the energized cross section again, and the bulging of the second section of the large-size pipe is completed by referring to step 3 above;

[0076] Step 5: Complete the first layer of bulging of the cross section in sequence

[0077] When the bulging of the second section of the above step 4 is completed, repeat the above step 4 until the bulging of the last section of the first layer of the large-size pipe is completed;

[0078] Step 6: Complete the second layer of bulging

[0079] After the first layer bulging of the large-sized pipe is completed, the two electrodes 10 are withdrawn from the leftmost end to the rightmost end, and the above steps 2-5 are repeated to complete the second layer bulging of the large-sized pipe;

[0080] Step 7: Tube bulging is completed

[0081] When the second layer of the tube is expanded in step 6, the above step 6 is repeated to complete the third layer of the tube until the expansion of the last layer; the expansion of the entire large-size closed tube is completed.

[0082] Embodiment 2:

[0083] like Figure 4 As shown, the electric-assisted progressive bulging device for large-size thin-walled pipes of difficult-to-deform alloys described in the present invention includes a punch, a central shaft, a coupling, a motor, a moving disk, an insulating block, a compression spring, an electrode, an annular pure copper block, a carbon brush, an insulating bracket, a wire, etc.

[0084] Two moving disks are mounted on the central shaft, and insulating blocks are mounted on the top of each. The electrode is inserted into the central hole of the moving disk through the compression spring; an annular pure copper block is mounted on each side of the punch, and insulating brackets are mounted at both ends of the central shaft. Carbon brushes are mounted to connect the annular pure copper block and the insulating bracket, and the electrode and the carbon brush are connected with a wire; the punch is sealed with a large-sized thin-walled part, and a constant air pressure P0 is introduced; outside the closed space, the central shaft and the motor are connected with a coupling. In this way, the motor is mounted outside the closed space and connected to the central shaft transmission, which simplifies the device structure compared with Example 1.

[0085] The electric-assisted progressive bulging device described in this embodiment can be used to obtain an electric-assisted progressive bulging method for large-size thin-walled pipes of difficult-to-deform alloys. The specific operation is as follows: Figure 1 , Figure 2 Schematic diagram implementation, the steps are as follows:

[0086] Step 1: Install the device

[0087] The bulging device is installed according to the above method, the cross-section workpiece and the central axis are sealed with two punches and corresponding seals, a predetermined constant air pressure P0 is introduced into the pipe, and the mold is installed in the corresponding position;

[0088] Step 2: Electrode adjustment and equipment power on

[0089] Before the equipment is powered on for rotation and heating, the two electrodes are moved to the right starting end of the section to be expanded by the moving disk 010 and a certain micro-distance is maintained. Then the motor is powered, the electrodes are powered, and the external motor drives the powered electrodes to rotate, and the powered small section between the two electrodes is heated. Figure 1 As shown in the schematic diagram;

[0090] Step 3: Disconnect the electrode and refill the device

[0091] When the temperature of the heated section rises to a predetermined value, the two electrodes and the motor are powered off, so that the equipment stops rotating and heating. Since the equipment has introduced the calculated bulging air pressure P0 in step 1, the heated small section section begins to bulge. After the bulging is completed, the left punch feeds the material to the right.

[0092] Step 4: Adjust the electrodes and power on again

[0093] After step 3 is completed, move the two electrodes to the left by one step, and then power the electrodes and the motor again, so that the two electrodes rotate and heat the energized section. Refer to step 3 above to complete the bulging of the second section of the large-size pipe. Figure 1 As shown;

[0094] Step 5: Complete the first layer of bulging

[0095] When the bulging of the second section of step 4 is completed, the above step 4 is repeated until the bulging of the last section of the first layer of the large-sized pipe is completed. From then on, the bulging of the first layer of the large-sized pipe is completed;

[0096] Step 6: Complete the second layer of bulging

[0097] After the first layer of bulging of the large-sized pipe is completed, the two electrodes are withdrawn from the leftmost end to the rightmost end, and the above steps 2-5 are repeated to complete the second layer of bulging of the large-sized pipe. Figure 1 , 2 As shown;

[0098] Step 7: Tube bulging is completed

[0099] When the second layer bulging of the pipe fitting is completed in step 6, the above step 6 is repeated to complete the third layer of the pipe fitting until the bulging of the last layer; at this point, the bulging work of the entire large-size pipe fitting is completed.

[0100] Embodiment 3:

[0101] like Figure 5 As shown, the electric-assisted progressive bulging device described in this embodiment includes a mechanical arm 3, an electrode, a central axis, a punch, etc. The power supply structure of the electrode is consistent with that of Embodiment 2 and is omitted in this figure.

[0102] The bases of the two robotic arms are installed on the central axis, and electrodes are installed at the ends of the robotic arms to contact the thin wall of the round tube; the two punches pass through the central axis and are sealed with the large-sized thin-walled parts to be processed, and a constant air pressure P0 is introduced.

[0103] The electric-assisted progressive bulging device described in this embodiment can be used to obtain an electric-assisted progressive bulging method for a large-sized tubular thin-walled part of a difficult-to-deform alloy. The specific operation is as follows: Figure 1 , Figure 2 Schematic diagram implementation, the steps are as follows:

[0104] Step 1: Install the device

[0105] The bulging device is installed according to the above method, the cross-section workpiece and the central axis are sealed with two punches and corresponding seals, a predetermined constant air pressure P0 is introduced into the pipe, and the mold is installed in the corresponding position;

[0106] Step 2: Electrode adjustment and equipment power on

[0107] Before the heating and bulging work begins, adjust the robot arm to place the two electrodes at the rightmost end of the large-sized thin-walled workpiece to be processed and keep a certain distance. Then the two electrodes are energized, and the robot arm rotates around the central axis to electrically heat the energized section between the two electrodes. Figure 1 , 2 As shown in the schematic diagram;

[0108] Step 3: Disconnect the electrode and refill the device

[0109] When the temperature of the heated section reaches a predetermined value, the two electrodes are powered off, the robot arm stops working, and the heated small section begins to bulge under the action of the constant air pressure P0 introduced in step 1. After the bulging is completed, the left punch feeds material to the right;

[0110] Step 4: Adjust the electrodes and power on again

[0111] After step 3 is completed, the robot arm is controlled to move the two electrodes to the left by one step, and then the electrodes are powered again. The robot arm rotates around the central axis to rotate and heat the energized section of the two electrodes. Referring to step 3 above, the second section of the large-size pipe is expanded. Figure 1 , 2 As shown;

[0112] Step 5: Complete the first layer of bulging

[0113] When the second section bulging of step 4 is completed, repeat the above steps to complete the first layer bulging of the large-size pipe;

[0114] Step 6: Complete the second layer of bulging

[0115] After the first layer of bulging of the large-sized pipe is completed, the two electrodes are withdrawn from the leftmost end to the rightmost end, and the above steps 2-5 are repeated to complete the second layer of bulging of the large-sized pipe. Figure 1 , 2 As shown;

[0116] Step 7: Tube bulging is completed

[0117] When the second layer bulging of the pipe fitting is completed in step 6, the above step 6 is repeated to complete the third layer of the pipe fitting until the bulging of the last layer; at this point, the bulging work of the entire large-size pipe fitting is completed.

Claims

1. An electrically assisted progressive bulging method for large-size thin-walled pipes of difficult-to-deform alloys, the forming characteristics of which are Follow these steps: (1) According to the characteristics of the tube to be processed, the target profile of the thin-walled tube is discretized into a number of to-be-formed regions along the radial direction, and then each to-be-formed region is discretized into a number of to-be-formed sub-regions along the axial direction of the thin-walled tube, and a forming path is planned according to the to-be-formed sub-regions; (2) After the components to be built into the thin-walled tube to be formed are assembled, they are assembled into the inner cavity of the thin-walled tube to be formed, and then the two sides of the thin-walled tube to be formed are sealed with a punch, and a gas with a predetermined pressure of P0 is introduced, where P0 is less than the plastic deformation yield pressure P of the tube at room temperature. S室 , greater than the plastic deformation yield pressure P of the pipe at high temperature T ST , finally, the mold is installed at the position corresponding to the thin-walled pipe to be formed; (3) Move the two electrodes to the right starting end of the thin-walled tube to be formed, maintain a certain distance d, then power the equipment, the two electrodes start to rotate, and rotate and heat the small section of the energized section within the range of the two electrodes; (4) When the temperature monitoring device inside the equipment detects that the temperature of the energized small section reaches the predetermined bulging temperature, the electrode and the motor are powered off, and the heated energized small section begins to bulge under the action of the air pressure P0, and the left punch moves to the right to achieve a small amount of material feeding during the bulging process until the bulging of the first section of the sub-area to be formed is completed; (5) After the heating and bulging of the first sub-region to be formed is completed, the two electrodes are moved to the left by a step distance d1 equal to d, and the electrodes are powered again so that the small section of the energized section within the range of the two electrodes is rotated and heated, and the bulging of the second sub-region to be formed is completed in the same manner as step 4; (6) After the bulging of the second sub-region to be formed is completed, step 4 is repeated until the bulging of the last sub-region to be formed of the first layer is completed; (7) After the bulging work of the first layer of the area to be formed is completed, the two electrodes are withdrawn to the right starting end of the thin-walled tube to be formed, and steps 3-6 are repeated until the bulging work of the last layer of the area to be formed of the thin-walled tube to be formed is completed, and the bulging of the tube is terminated.

2. The electrically assisted progressive bulging method for large-size thin-walled pipes of difficult-to-deform alloys according to claim 1 is characterized in that: The electrically assisted progressive bulging method for large-size thin-walled pipes of difficult-to-deform alloys is suitable for thin-walled pipe structures with a diameter of more than 1.5 meters.

3. An electrically assisted progressive bulging device for large-size thin-walled pipes of difficult-to-deform alloys, characterized in that: It includes a mold, an electric auxiliary heating component, a punch, a central axis, an electrode positioning mechanism, and a control device; wherein: The mold is provided with a forming cavity; the thin-walled pipe to be formed is coaxially arranged with the forming cavity; The central axis is arranged along the axis of the forming cavity; The punches described above have two punches, punch a1 and punch b1; the two ends of the thin-walled tube to be formed are sealed by punch a1 and punch b1 respectively; the inside of the tube cavity of the thin-walled tube to be formed with both ends sealed is preset with a gas with a pressure of P0; The electric auxiliary heating assembly has two components, namely, an electric auxiliary heating assembly and an electric auxiliary heating assembly, both of which include an annular pure copper block, a carbon brush, a wire, and an electrode. The electrode is in contact with the inner wall of the thin-walled pipe to be formed, and the electrode is connected to the carbon brush fixed on the annular pure copper block through the wire. The annular pure copper block of the electric auxiliary heating assembly a2 is fixed to the punch a1, and the annular pure copper block of the electric auxiliary heating assembly b2 is fixed to the punch b1. The electrode positioning mechanism is installed on the central axis and has two power output ends, namely, power output end a3 and power output end b3. The power output end a3 of the electrode positioning mechanism is connected to the electrode of the electric auxiliary heating component a2, and the power output end b3 of the electrode positioning mechanism is connected to the electrode of the electric auxiliary heating component b2. The electrode positioning mechanism is connected to the control device signal, and can drive the electrodes connected to the power output ends to form the discrete layers of the target surface layer by layer in the radial direction according to the forming process path planned in the control device, so as to manufacture the target surface that meets the requirements layer by layer in the forming process part; and each layer of the to-be-formed area drives the electrodes connected to each other through the two power output ends of the electrode positioning mechanism according to the planning of the forming process path, and heats the to-be-formed sub-areas within the range of the two electrodes in the to-be-formed part one by one, and finally realizes the gas expansion forming of the thin-walled pipe fitting step by step under the action of the gas pressure P0; The electrodes of the electric auxiliary heating component a2 and the electrodes of the electric auxiliary heating component b2 can both step and translate along the central axis under the action of the electrode positioning mechanism; at the same time, the electrodes of the electric auxiliary heating component a2 and the electrodes of the electric auxiliary heating component b2 in the energized state can rotate around the central axis under the power output of their respective electrode positioning mechanisms, so as to rotationally heat the sub-region to be formed within the range of the two electrodes of the thin-walled pipe to be formed until the sub-region to be formed reaches a predetermined expansion temperature; the material of the sub-region to be formed is expanded under the action of the air pressure P0 to obtain a local air expansion forming surface corresponding to the sub-region to be formed.

4. The electrically assisted progressive bulging device for large-size thin-walled pipes made of difficult-to-deform alloys according to claim 3 is characterized in that: The electrode positioning mechanism includes a rotation drive device for driving the central axis to rotate and a translation mechanism for driving the electrode to translate; the power output end of the rotation drive device is connected to the central axis; the fixed end of the translation mechanism is fixed to the central axis, and the actuating end of the translation mechanism is connected to the electrode.

5. The electrically assisted progressive bulging device for large-size thin-walled pipes made of difficult-to-deform alloys according to claim 4 is characterized in that: The rotary drive device comprises a motor, a motor sleeve and a reduction gear; the motor is built into the lumen of the thin-walled pipe to be formed, and the base of the motor is sleeved on the central shaft through the motor sleeve, while the power output end of the motor is connected to the central shaft through the reduction gear.

6. The electrically assisted progressive bulging device for large-size thin-walled pipes made of difficult-to-deform alloys according to claim 4 is characterized in that: The translation mechanism includes a moving disk and a slide rail; a circular disk is coaxially arranged on the central axis, the slide rail is supported by the circular disk, the moving disk is movably mounted on the slide rail, and the electrode is mounted on the moving disk; the carbon brush is supported on the slide rail by an insulating bracket.

7. The electrically assisted progressive bulging device for large-size thin-walled pipes made of difficult-to-deform alloys according to claim 4 is characterized in that: The rotary drive device comprises a motor and a coupling; the motor is externally arranged at one end of the thin-walled pipe to be formed, and the power output end of the motor is connected to the central shaft through the coupling; The translation mechanism comprises a movable plate which is movably mounted on the central axis, and an electrode which is mounted on the movable plate, and the end of the electrode can contact the inner wall of the thin-walled pipe to be formed; the carbon brush is supported on the central axis by an insulating bracket.

8. The electrically assisted progressive bulging device for large-size thin-walled pipes made of difficult-to-deform alloys according to claim 3 is characterized in that: A compression spring is arranged between the end of the electrode and the moving disk.

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