Multi-field composite local continuous bulging die, system and method for special-shaped variable-cross-section long pipe fitting

Abstract

The multi-field composite local continuous bulging die comprises an upper die and a lower die, the upper die and the lower die are each provided with a sliding guide rail and a sliding rail which are used for enabling the die to move between forming machines, and the upper die and the lower die are each provided with a water cooling system. The water cooling system comprises water inlet and outlet channels, auxiliary channels and hydraulic valves, heating structures are arranged on the two sides of each auxiliary channel, when the long pipe fitting is bulged, the hydraulic valves and the heating structures are stressed, the hydraulic valves block the water inlet channels and the water outlet channels so as to close water inlet and outlet on the two sides of the auxiliary channels, and the ends of the heating structures are attached to the long pipe fitting to form a local current loop. And gas is introduced into the long pipe fitting for bulging. Compared with a traditional machining method, the continuous sectional bulging method is adopted, and the requirement for the equipment specification can be greatly lowered.

Description

Technical Field

[0001] This invention relates to pipe bulging, specifically to a multi-field composite local continuous bulging mold, system, and method for irregularly shaped variable cross-section long pipes. Background Technology

[0002] With the increasing demands on component performance in high-end manufacturing fields such as aerospace and energy equipment, the processing and application of difficult-to-machine continuous variable cross-section long pipes are becoming more and more widespread. These pipes are usually made of difficult-to-machine materials such as high-temperature alloys and titanium alloys. Machining them requires overcoming multiple technical limitations, so in recent years, the processing of difficult-to-machine continuous variable cross-section long pipes has become a research hotspot.

[0003] However, traditional processing methods require large machines and molds for machining long, continuously variable cross-section pipes, which are difficult to process. Without high-tonnage, large-table internal high-pressure forming machines, machining these difficult-to-process, continuously irregularly shaped, variable cross-section long pipes is extremely challenging. Furthermore, precision control during the machining of continuously variable cross-section long pipes is difficult. Long pipes can bend due to thermal deformation and other factors, making it difficult to guarantee coaxiality and smooth transitions between different cross-sections. Secondly, the machining efficiency of long pipes is relatively low. Because machining long pipes requires long molds for fitting, and long molds are expensive, these pipes often cannot be machined in one go, thus requiring multiple clamping operations, making continuous and efficient machining impossible.

[0004] In the prior art, Chinese patent application number 202411444250.4 discloses a method for hot-gas bulging A and B column tube beams integrally die-casting with aluminum alloy. Specifically, the method involves: first, cutting and deburring the tube blank; then, bending the corresponding tube blank to obtain a bent intermediate part; and finally, pressing the bent intermediate part; placing the A and B parts into a mold and hot-gas bulging them, heating them to a thermoplastic state, and filling them with high-pressure gas to bulge them into the shape inside the mold, thus obtaining column A, the first column B, and the second column B; and cutting at both ends of column A and the lower ends of the first and second column B to create openings for pressure holding during subsequent aluminum alloy die-casting processes. The ports are then welded shut at the top ends of the first and second B-pillar tube beams. The A-pillar tube beam is welded to the first and second B-pillar tube beams placed side-by-side to form a single unit, creating a tight connection between the middle of the A-pillar tube beam and the top ends of the first and second B-pillar tube beams. The entire A-pillar tube beam and the first and second B-pillar tube beams are placed in a die-casting mold. Pressure is maintained by inflating the tube beam component through the open end, while molten aluminum alloy is injected into the mold cavity. An aluminum alloy connector is formed at the connection point between the middle of the A-pillar tube beam and the top ends of the first and second B-pillar tube beams. The slag is removed, and the pressure-maintaining open port is cut off, resulting in a one-piece A-pillar and B-pillar structure. However, this method requires large forming machines for processing tubes with many variable cross-sections and longer tubes. Summary of the Invention

[0005] Purpose of the invention: To address the above-mentioned shortcomings, this invention provides a multi-field composite local continuous bulging mold for irregularly shaped variable cross-section long pipes with low cost and high processing accuracy, as well as a multi-field composite local continuous bulging system and a multi-field composite local continuous bulging method for irregularly shaped variable cross-section long pipes.

[0006] Technical Solution: To solve the above problems, this invention employs a multi-field composite local continuous bulging mold for irregularly shaped variable cross-section long pipe fittings, including an upper mold and a lower mold. The upper and lower molds together form an bulging cavity. A first sliding guide rail is provided on the upper surface of the upper mold, and a first sliding slide rail is provided on the lower surface of the lower mold. The first sliding guide rail and the first sliding slide rail are used for the mold to move relative to the forming machine. Both the upper and lower molds are equipped with a water cooling system. The water cooling system includes two parallel water inlet channels and water outlet channels, several secondary channels connecting the water inlet channels and water outlet channels, and several hydraulic valves. The water inlet channels and water outlet channels are used to continuously supply flowing cooling water. Each secondary channel has a hydraulic valve on both sides. The hydraulic valve includes an input end extending out of the mold and an output end that simultaneously blocks the water inlet channels and water outlet channels. Each secondary channel has a through hole on both sides connecting the outside and the bulging cavity. The through hole is located between the hydraulic valve and the secondary channel. Between the channels, a heating structure is installed in the through hole. The heating structure is used to connect the external circuit and the long tube. The heating structure is an elastic structure. When the long tube expands, the upper mold and the lower mold close, and the forming machine generates sufficient closing force on the upper mold and the lower mold. The two ends of the long tube are sealed and pressurized inert gas is introduced. Cooling water is introduced into the water inlet channels of the upper mold and the lower mold. The water inlet channel, the water outlet channel and the secondary channel form a circulating cooling water circuit. The hydraulic valve and the heating structure are subjected to the pressure of the forming machine. The input end of the hydraulic valve is pressurized, and the output end simultaneously blocks the water inlet channel and the water outlet channel, thereby closing the water inlet and outlet on both sides of at least one secondary channel. At least two heating structures are compressed and their ends are attached to the long tube to form a local current circuit. Both heating structures are located within the blocked water inlet channel and water outlet channel range, ensuring that the long tube within this range is heated to the forming temperature and produces a local expansion film.

[0007] Furthermore, the hydraulic valve includes a T-shaped hydraulic chamber, liquid disposed within the hydraulic chamber, a piston disposed in the narrow portion of the hydraulic chamber, movable water-blocking blocks disposed at both ends of the wide portion of the hydraulic chamber, and a second return spring. The second return spring is disposed at the end of the movable water-blocking block. The piston rod of the piston extends out of the mold. The piston rod is the input end of the hydraulic valve, and the movable water-blocking block is the output end of the hydraulic valve. When the piston rod is compressed by force, the liquid in the hydraulic chamber pushes the movable water-blocking blocks at both ends to move to both sides, thereby blocking the inlet and outlet water channels. When the piston rod is depressurized, the second return spring pushes the movable water-blocking blocks back into the hydraulic chamber, and the liquid in the hydraulic chamber pushes the piston to extend the piston rod.

[0008] Furthermore, a movable slide is fixedly provided at the outer end of both the piston rod and the energized conductive block. The movable slide is provided with an inclined guide surface on its side and a movable ball on its top. The movable ball is used to reduce the frictional resistance between the piston rod and the forming machine, and the inclined guide surface is used to ensure that the piston rod or the energized conductive block can move smoothly into the forming machine when the mold moves.

[0009] Furthermore, the movable ball bearings on the top of the moving slide of the energized conductive block are lubricated with conductive lubricating oil, which is made by adding conductive solid particles to the base oil.

[0010] Furthermore, the heating structure includes a conductive block and a heating electrode head. The heating electrode head includes a connecting part and a contact part. One end of the connecting part is fixedly connected to the conductive block, and the other end is provided with a groove. One end of the contact part is inserted into the groove of the connecting part, and the other end extends into the expansion cavity. One end of the conductive block extends outward from the mold, and the other end is fixedly connected to the connecting part of the heating electrode head. An elastic component is provided inside the groove of the connecting part of the heating electrode head. The connecting part and the contact part are connected through the elastic component. The conductive block is connected to the mold through a first return spring. When the conductive block and the heating electrode head are pressed, the elastic component and the first return spring are compressed. The elastic component is used to increase the adhesion between the heating electrode head and the long tube. When the pressure is removed, the elastic component and the first return spring return to their original positions.

[0011] Furthermore, the long pipe is a difficult-to-machine continuously variable cross-section pipe, the length of which is greater than the maximum size of the worktable of the existing special forming machine, and the material of the long pipe is a difficult-to-deform alloy material, including titanium alloy and high-strength steel.

[0012] The present invention discloses a multi-field composite local continuous bulging system for irregularly shaped variable cross-section long pipe fittings, comprising a local continuous bulging mold for the aforementioned irregularly shaped variable cross-section long pipe fittings, a forming machine, and a base. The base and a base support are fixedly connected. The base is provided with a second sliding guide rail. The local continuous bulging mold is disposed on the base, and a first sliding rail on the lower surface of the lower mold moves along the second sliding guide rail on the upper surface of the base. Two downward pressure water columns and an electrically powered platform located between the two downward pressure water columns are fixed on the base. The downward pressure water columns are used to press against the input end of the hydraulic valve of the lower mold. The power-on platform is used to support the heating structure of the lower mold. The forming machine includes a press platform. A second sliding rail is provided on the lower surface of the press platform. Two upper water columns and a pressure head located between the two upper water columns are provided between the second sliding rails. The second sliding rail cooperates with a first sliding guide rail and moves along the first sliding guide rail. The upper water columns are used to support the input end of the hydraulic valve of the upper mold. The pressure head is used to support the heating structure of the upper mold. The pressure head and the power-on platform are connected to an external circuit, and a local heating circuit is formed with the long pipe through the heating structure.

[0013] Furthermore, the pressure head includes two energized parts and an insulating block disposed between the two energized parts, with the two energized parts respectively connected to the positive and negative terminals of an external circuit.

[0014] The bulging method of the multi-field composite local continuous bulging system for irregularly shaped variable cross-section long pipes of the present invention includes the following steps:

[0015] Step 1: Install the upper mold with the press platform, place the long pipe to be expanded into the expansion cavity formed by the upper and lower molds, install the upper and lower molds together, and move the mold to the position corresponding to the power-conducting block of the mold on the power-conducting part of the press platform.

[0016] Step 2: The press platform of the forming machine presses down, closes the mold and provides closing force, seals both ends of the long pipe and introduces pressurized gas into the long pipe, and introduces circulating cooling water into the water cooling system of the upper and lower molds. The press platform continues to press down, and the two upper and lower press water columns close the hydraulic valves on both sides of the corresponding secondary channels. The press head and the power platform press against the heating structure until the end of the heating structure is in contact with the long pipe. The press head, heating structure and local pipe of the processing area of ​​the forming machine form a current loop, the water flow loop of the processing area forms a local static state, and the remaining water flow loop continues to circulate and cool.

[0017] Step 3: The temperature of the local pipe fittings in the processing area rises under the heating of electric current, the material of the pipe fittings softens, the deformation resistance decreases, and it expands under the action of internal gas pressure;

[0018] Step 4: After the bulging of the processing area is completed, the mold is driven to move horizontally without removing the clamping force, so that the pressure head and the power platform of the forming machine press down on the heating structures on both sides of the next channel to carry out the bulging of the next processing area.

[0019] Step 5: Repeat step 4 to process the long pipe in multiple sections until the final target pipe is completed.

[0020] Furthermore, baffles are provided on both sides of the upper mold, and lifting buckles are provided on the press platform of the forming machine. When the upper mold and the press platform are installed together, the lifting buckles are engaged with the baffles to raise the press platform. The upper mold is lifted by the engagement of the lifting buckles and the baffles on the press platform, and the long pipe is removed to achieve demolding.

[0021] Beneficial Effects: Compared with existing technologies, the significant advantages of this invention are: it adopts a continuous segmented processing method, which greatly saves costs and provides a more reliable processing solution compared with traditional processing methods. By moving the mold to process the pipe fitting locally, a complete pipe fitting can be obtained through continuous multi-segment processing. This not only improves the accuracy of pipe fitting processing but also greatly enhances the reliability of processing, solving the problem of not needing large processing equipment and being able to process difficult-to-machine continuous variable cross-section long pipe fittings with small equipment.

[0022] Using an internal high-pressure forming machine, when the press platform of the internal high-pressure forming machine presses down, it can apply a clamping force to the upper mold. On the other hand, the material being processed is a pipe fitting, which is formed using air expansion and electric auxiliary heating, eliminating the need for material removal and resulting in high material utilization. The invention utilizes segmented bulging processing. Firstly, processing long, irregularly shaped, variable-section pipe fittings requires a large forming force. When a large-tonnage forming machine is unavailable, it is impossible to provide the ultimate forming force. Now, by using a small-tonnage forming machine, the effect of dispersing force can be achieved through segmented processing, which can also produce finished pipe fittings. Secondly, segmented processing can locally reduce the yield strength of the material, reducing the risk of wrinkling and cracking during overall bulging and improving the dimensional consistency of the parts.

[0023] By using a cold water circulation loop inside the mold to cool the unprocessed pipe section, the forming quality of the pipe can be ensured and guaranteed. Compared with other cooling methods that are difficult to cover the inside of long pipes and the turning points of variable cross sections, this method can remove heat from the pipe section being processed in time, significantly improving the dimensional accuracy and surface finish of the product.

[0024] The method of forming by heating electrode head involves gas expansion inside the tube, and current forming a circuit with the local tube through the conductive block. Heat is generated on the surface of the tube, and the tube deforms into the finished shape under the deformation drive of the heating electrode head. This method can greatly maintain the uniform heating of the processed part and the pressure generated in the gas expansion area is almost equal, thus maximizing the yield. Attached Figure Description

[0025] Figure 1 This is a longitudinal cross-sectional view of the partially movable water-blocking block and the electrically conductive block in this invention, which have already started operating.

[0026] Figure 2 This is a longitudinal cross-sectional view of the partially movable water-blocking block and the electrically conductive block in the present invention when they are not in operation.

[0027] Figure 3 This is a cross-sectional view of the water circuit inside the upper mold of the present invention, where part of the water circuit is blocked and the remaining water circuits are circulating.

[0028] Figure 4 This is a schematic cross-sectional view of the water circulation loop inside the upper mold in this invention.

[0029] Figure 5 This is a schematic diagram of the left cross-section of the mold when the hydraulic valve inside is not in operation.

[0030] Figure 6 This is a schematic diagram of the left cross-section of the hydraulic valve inside the mold in this invention during operation.

[0031] Figure 7 This is a schematic diagram of the heating structure in this invention.

[0032] Figure 8This is a cross-sectional schematic diagram of the heating structure in this invention.

[0033] Figure 9 This is a schematic diagram of the overall assembly structure of the device already installed in this invention.

[0034] Figure 10 This is a side view of the overall assembly structure in this invention.

[0035] Figure 11 This is a front view of the overall assembly structure in this invention.

[0036] Figure 12 This is a diagram showing the shape changes of the irregularly shaped pipe before and after bulging in this invention.

[0037] Figure 13 This is a schematic diagram of a portion of the cross-section of the irregularly shaped variable cross-section pipe fitting in this invention.

[0038] Figure 14 This is a schematic diagram of the heating structures in the mold of the present invention.

[0039] Figure 15 This is a cross-section and a partially enlarged schematic diagram of the assembly drawing in this invention.

[0040] Figure 16 This is a schematic diagram illustrating the process of the electrically conductive block and heating electrode head being pressed down by the press platform during the movement of the mold in this invention.

[0041] Press platform 1; Power supply part 2; Partial continuous expansion mold 3; Upper mold 3-1; Lower mold 3-2; Heating electrode head 4; Connecting part 4-1; Contact part 4-2; Insulating block 5; First return spring 6; Power supply block 7; Long pipe 9; Insulating ring 10; Water column 11; Upper water column 11-1; Lower water column 11-2; Piston 12; Water pipe channel 13; Water inlet channel 13-1; Water outlet channel 13-2; Secondary channel 13-3; Sealing ring 14; Second return spring 15; Pressurized moving part 16; Moving water blocking block 17; Liquid 18; Movable ball 19; First sliding guide rail 20; Baffle 21; Roller 22; Lifting buckle 23; Base 24; Base bracket 25; Second sliding guide rail 26; Power supply platform 27; Positioning pin 29; Square hole rectangular block 30; Sliding groove 31; Second sliding slide rail 32; Elastic part 33; First sliding slide rail 34. Detailed Implementation

[0042] like Figures 1 to 6As shown in this embodiment, a multi-field composite local continuous bulging mold 3 for an irregularly shaped variable cross-section long tube is used. The long tube 9 is a difficult-to-machine continuously variable cross-section tube. The length of the long tube 9 is greater than the maximum size of the worktable of the existing special forming machine. The length of the long tube 9 is more than 7-8 times the size of the worktable. The material of the long tube 9 is an alloy material, including titanium alloy and high-strength steel. The local continuous bulging mold 3 includes an upper mold 3-1 and a lower mold 3-2. The upper mold 3-1 and the lower mold 3-2 together form an bulging cavity. A first sliding guide rail 20 is provided on the upper surface of the upper mold. The lower mold has a first sliding rail 34 on its lower surface. The upper mold's first sliding guide rail 20 engages with the forming machine's second sliding rail 32. The lower mold's first sliding rail 34 engages with the second sliding guide rail 26 on the base. The partially continuous bulging mold 3 moves relative to the forming machine. Both the upper mold 3-1 and the lower mold 3-2 are equipped with water cooling systems. The water cooling system includes two parallel water inlet channels 13-1 and water outlet channels 13-2, several secondary channels 13-3 connecting the water inlet channels 13-1 and water outlet channels 13-2, and several hydraulic valves. 2. A water inlet channel 13-1 and a water outlet channel 13-2, running through the length of the upper and lower molds, are used to continuously supply cooling water. Each secondary channel 13-3 has a hydraulic valve on both sides. The hydraulic valve includes an input end extending out of the mold and an output end that simultaneously blocks the water inlet and outlet channels. Each secondary channel has a through hole on both sides connecting to the outside and the bulging cavity. The through hole is located between the hydraulic valve and the secondary channel. A heating structure is installed inside the through hole, which is used to connect to an external circuit. The heating structure is an elastic structure. When the long tube is bulging, the upper and lower molds close, and the forming machine generates sufficient closing force. Both ends of the part are sealed and pressurized inert gas is introduced. Cooling water is introduced through the water inlet and outlet channels of the upper and lower molds to form a circulating cooling water circuit. The hydraulic valve and heating structure are subjected to the pressure of the forming machine. The input end of the hydraulic valve is pressurized, and the output end simultaneously blocks the water inlet and outlet channels, thereby closing the water inlet and outlet on both sides of at least one secondary channel. At least two heating structures are compressed and their ends are attached to the long tube to form a local current circuit. Both heating structures are located within the blocked water inlet and outlet channels, ensuring that the local material of the long tube within this range is heated to the forming temperature and produces a local bulging film.

[0043] like Figure 5 and Figure 6As shown, the hydraulic valve includes a T-shaped hydraulic chamber, liquid 18 disposed within the hydraulic chamber, a piston 12 disposed in the narrow portion of the hydraulic chamber, movable water-blocking blocks 17 disposed at both ends of the wide portion of the hydraulic chamber, and a second return spring 15. The second return spring 15 is disposed at the end of the movable water-blocking block 17. The piston rod of the piston 12 extends out of the mold, and the piston rod is the input end of the hydraulic valve. The movable water-blocking block 17 is the output end of the hydraulic valve. The movable water-blocking block 17 is connected to the second return spring 15 via a pressure-bearing moving component 16. The diameter of the connecting piece between the movable water-blocking block 17 and the pressure-bearing moving component 16 is smaller than that of the movable water-blocking block 17. When the movable water-blocking block 17 and the pressure-bearing moving component 16... When the connecting piece between parts 16 is located between the inlet and outlet channels, it will not block the inlet and outlet channels. One end of the second return spring 15 is fixedly connected to the pressure-bearing moving part 16, and the other end is fixedly connected to the wall of the hydraulic chamber. When the piston rod of piston 12 is compressed, piston 12 pushes the liquid in the hydraulic chamber. The liquid in the hydraulic chamber pushes the movable water-blocking blocks at both ends of the wide part of the hydraulic chamber to move to both sides, thereby blocking the inlet and outlet channels. When the piston rod is depressurized, the second return spring 15 pushes the pressure-bearing moving part 16, thereby pushing the movable water-blocking blocks back into the hydraulic chamber. The liquid in the hydraulic chamber pushes the piston to extend the piston rod, and the piston rod returns to the limit apex. A movable slide is fixedly provided at the outer end of the piston rod. Inclined guide surfaces are provided on both sides of the movable slide, and movable ball bearings 19 are provided at the top. The movable ball bearings 19 are used to reduce the frictional resistance between the piston rod and the forming machine. The inclined guide surfaces are used to ensure that the piston rod moves smoothly into the forming machine when the mold moves. In this embodiment, the liquid 18 in the hydraulic chamber is hydraulic oil.

[0044] Waterproof sealing rings are installed in multiple places in the water pipe passage. Four symmetrical sealing rings 14 are installed at the water blocking ports at both ends of the left and right movable water blocking block 17. Two pairs of waterproof sealing rings are also installed at the piston. The material is silicone rubber, which is resistant to high temperature and oil. The heat resistance temperature of the high temperature silicone rubber sealing ring is 200 to 230°C. The pipe is electrically heated to a forming temperature of more than 800°C. After the mold is insulated and heat is conducted, the temperature of the sealing ring is already low. The sealing ring is located in the water cooling system. After water cooling, its temperature is below 100°C. For the processing area where the water does not circulate, the temperature is below 200°C.

[0045] like Figure 7 and Figure 8As shown, the heating structure includes a conductive block 7 and a heating electrode head 4. The heating electrode head 4 includes a connecting part 4-1 and a contact part 4-2. One end of the connecting part 4-1 is fixedly connected to the conductive block 7, and the other end is provided with a groove. One end of the contact part 4-2 is inserted into the groove of the connecting part, and the other end extends into the expansion cavity. One end of the conductive block 7 extends outward from the mold, and the other end is fixedly connected to the connecting part of the heating electrode head. The groove of the connecting part of the heating electrode head 4 has an elastic component 33. The connecting part and the contact part are connected by the elastic component 33. When the conductive block 7 and the heating electrode head 4 are pressed, the elastic component 33 is compressed. The elastic component 33 increases the adhesion force between the heating electrode head and the long tube. In this embodiment, the elastic component 33 is a spring, and the two ends of the spring are fixedly connected to the connecting part 4-1 and the contact part 4-2 of the heating electrode head 4, respectively. A conductive movable slide is fixedly installed at the outer end of the conductive block 7. An inclined guide surface is provided on the side of the movable slide, and a movable ball bearing 19 is provided on the top. The movable ball bearing 19 is used to reduce the frictional resistance between the conductive block 7 and the forming machine. The inclined guide surface ensures that the conductive block 7 moves smoothly into the forming machine when the mold moves. The movable ball bearing on the top of the movable slide of the conductive block 7 is lubricated with conductive lubricating oil, which is obtained by adding conductive solid particles to base oil. A first return spring 6 is also sleeved on the outside of the conductive block 7. One end of the first return spring 6 is fixedly connected to the bottom surface of the movable slide, and the other end is fixedly connected to the mold. When the conductive block 7 is subjected to pressure from the forming machine, the first return spring 6 is compressed; when the pressure is removed, the first return spring 6 returns to its original position, and the movable slide of the conductive block 7 extends out of the mold.

[0046] In this embodiment, a total of 2N+1 electrically conductive blocks are arranged radially in the upper and lower molds. The electrically conductive blocks are connected to the molds via a first return spring 6. They are moved downwards by the pressure head of the press platform of the inner high-pressure forming machine until the heating electrode head 4 at the lower end of the electrically conductive block contacts the tube, forming a local circuit and raising the temperature of the processed tube in that area. Similarly, the energized platform of the base also presses the electrically conductive blocks, driving the heating electrode heads of the blocks to contact the tube, forming a circuit. The temperature in the heating zone needs to be controlled between 800-950 degrees Celsius. The Joule heating is controlled by adjusting the current and voltage to ensure the processed alloy material reaches the optimal deformation zone temperature.

[0047] like Figures 9 to 11As shown, this embodiment discloses a local continuous bulging system for a long, irregularly shaped, variable-section pipe fitting, including a local continuous bulging mold, a forming machine, a base 24, and a base support 25. The base is provided with a second sliding guide rail 26. The local continuous bulging mold is mounted on the base, and a first sliding rail 34 on the lower surface of the mold moves along the second sliding guide rail 26 on the base. Two downward-pressing water columns 11-2 and an electrically powered platform 27 located between the two downward-pressing water columns are fixed on the base. The downward-pressing water columns 11-2 are used to press against the piston rod of the hydraulic valve of the lower mold, and the electrically powered platform 27 is used to press against... The heating structure of the lower mold and the forming machine include a press platform 1. Two second sliding rails 32 are arranged on the lower surface of the press platform. Two upper water columns 11-1 and a press head located between the two upper water columns are arranged between the two upper water columns. The press head includes two energized parts 2 and an insulating block 5 located between the two energized parts 2. The upper water columns 11-1 are used to press against the piston rod of the hydraulic valve of the upper mold. The two energized parts 2 of the press head are used to press against the heating structure of the upper mold. The two energized parts of the press head and the energized platform are connected to an external circuit, forming a local heating circuit with the long pipe through the heating structure. The insulating block 5, placed in the middle of the energized part 2 of the press platform, is used to ensure a complete and reliable current circuit, guaranteeing the integrity of the processed product. Similarly, an insulating block is also arranged in the middle of the energized area on the energized platform 27 on the lower base 24.

[0048] Rollers 22 can also be installed on the upper water column 11-1 and the lower surface edge of the pressure head to further facilitate the movement of the piston rod and the power-conducting block into the forming machine when the mold moves.

[0049] Furthermore, insulating rings 10 are installed at the front and rear ports of the mold to block the current flow to conductive parts such as the mold, ensuring the safety of equipment and operators. On the other hand, they are used to seal and prevent leakage, preventing high-pressure gas leakage.

[0050] Sliding grooves 31 are formed on both sides of the baffle 21 and both sides of the lower mold. The sliding grooves 31 are aligned with the mold displacement direction. The upper mold and the press platform are fixed together by rectangular blocks 30 with square holes to maintain their coaxiality. The upper part of the rectangular blocks 30 with square holes is fixedly connected to the press platform by a positioning pin 29. The positioning pin 29 below the square hole of the rectangular blocks 30 is positioned in the sliding groove 31 on the side of the baffle 21 and moves along the sliding groove 31. The press platform 1 is fixedly connected to a hook-shaped lifting buckle 23. The baffle 21 is inserted into the lifting buckle 23 from top to bottom. Two base supports 25 are fixedly connected to both sides of the base. The mold is located between the two base supports 25. Positioning pins are set on the base supports 25. The positioning pins are positioned in the sliding groove 31 on the side of the lower mold and move along the sliding groove 31. The purpose of this design is to ensure that the mold moves in the predetermined direction of the horizontal guide rail, ensuring the reliability of the structure. Four rectangular blocks 30 with square holes are installed at the front and rear of the upper mold. Similarly, two base supports 25 are also installed on the lower mold to ensure its directional movement.

[0051] For example Figure 12 The irregularly shaped long pipe shown needs to be processed into an irregularly shaped long pipe with a variable cross-section. The cross-sectional shape of the irregularly shaped long pipe with a variable cross-section is as follows: Figure 13 As shown, the heating electrode head 4 can be configured with contact parts of different shapes at different cross-sections to contact the long tube, such as... Figure 14 As shown, during the initial processing, the water in the water pipe channel 13 circulates normally, cooling the pipe fittings. The press platform and base of the internal high-pressure forming machine are respectively equipped with a water column 11 and an electric conductor 2. Sliding guides and sliding rails are installed at the upper and lower ends of the mold. Sliding guides and sliding rails are also installed on the base of the internal high-pressure forming machine and on the underside of the press platform. Initially, the water pipe circuit is in a continuous circulation state. By expanding the air inside the pipe fitting and using localized current heating, the material springback of that part of the pipe fitting is reduced, thereby achieving plastic deformation to reach the target pipe fitting. Insulation layers are installed near the electric conductor and electric conductor structure of the internal high-pressure forming machine, and the inside of the mold has a coating of insulating material, such as ceramic.

[0052] The processing method involves locally heating the pipe fitting to soften the material and reduce its deformation resistance, causing it to expand under the pressure of internal gas. The gas pressure is used to induce plastic deformation in the processing area of ​​the pipe fitting to obtain the target finished product. Figure 2 and Figure 4The images show cross-sectional views of the mold before processing. At this stage, air is introduced into the pipe, with a pressure of approximately 5.0-10.0 MPa, reaching the critical state where the pipe will not deform. When the long pipe is placed into the mold, the head of the heating electrode rests precisely on the pipe, making complete contact with its surface. No force is applied to the pipe, forming a local current loop for localized heating. Air is then injected into both ends of the pipe, utilizing the characteristic that locally heated materials are more prone to plastic deformation. The final shape is achieved through air expansion and the heating electrode. The upper and lower molds each have two pairs of water inlets and outlets. Water is continuously injected into these channels, circulating throughout the mold. The water absorbs the heat from the pipe, cooling the non-processed areas.

[0053] The process employs segmented processing. When processing the first segment of the pipe, the mold is aligned with the conductive area of ​​the two adjacent heating structures at the outermost edge of the press platform. The power supply device of the press platform of the inner high-pressure forming machine is turned on, and the water flow is normal. The pressure is slowly applied, and when the energized conductive block comes into contact with the conductive part at the lower end of the press platform of the inner high-pressure forming machine, the current begins to flow into the expected circuit. At the same time, the water column squeezes the water-blocking element piston 12, and the piston 12 squeezes the internal liquid, driving the left and right moving water-blocking block 17 to move and block the water flow in the processing area. Except for the water flow in the processing area, the water flow circuits on the left and right sides are divided into two sections of circulating water circuits through the secondary channel to cool the unprocessed area. At this time, due to the flow of current in the processing area, the heating electrode head is also activated, converting electrical energy into heat energy. The temperature of the local pipe increases, the pipe material softens, and the deformation resistance decreases. At the same time, gas is introduced, and the gas pressure inside the pipe remains constant. At this time, due to the internal gas pressure, the pipe gradually moves closer to the target that is close to the heating electrode head, thus obtaining the finished pipe in that part.

[0054] Once this section of the processing area is completed, the inner high-pressure forming machine remains stationary while driving the mold to move, as follows: Figure 15 As shown, the movable ball bearing 19 rolls relative to the press platform, causing the energized conductor and piston rod to move out of the lower surface of the press platform of the inner high-pressure forming machine. When the two components return to their original positions, the elastic potential energy of the first restoring spring of the heating electrode head 4 returns to its initial state. The second restoring spring in the hydraulic valve drives the left and right pressure-moving components 16 to reset, simultaneously driving the internal hydraulic oil. The hydraulic oil drives the piston 12 to move, and the piston rod of the piston 12 just returns to its upper limit position. After cooling the processed pipe, as... Figure 16As shown, the mold is moved to the point where the distance between two adjacent conductive blocks is reduced. The piston rod and conductive blocks are guided to the lower surface of the press platform via the inclined guide surface of the moving slide. Moving the mold, compared to re-clamping the press platform, significantly saves time and reduces repeated clamping errors, improving forming accuracy and lowering the risk of secondary damage during thin-walled pipe processing. Repeating these steps allows for continuous processing of multiple pipe sections, ultimately yielding a complete finished pipe.

[0055] After the entire pipe fitting is processed, the press platform moves upward. Its lifting buckle 23 cooperates with the mold baffle 21 to lift the upper mold and remove the pipe fitting. Initially, the lifting buckles 23, installed on both sides of the press platform, need to be inserted under the baffles 21 on both sides of the upper mold's upper surface. When the upper and lower molds are fully fitted, the bottom surface of the press platform applies a certain clamping force to the upper mold. At the same time, the lifting buckles 23 and baffles 21 do not interfere with each other. The mold is then moved to the initial processing position, where the energized part of the press platform corresponds to the foremost energized conductive block on the upper surface of the mold. Afterward, the press platform remains stationary, while the lifting buckles and baffles move relative to each other in their initial horizontal position without interference during processing. The mold is moved until processing is complete. Only then do the lifting buckles 23 contact the baffles 21 after the press platform moves upward, disengaging the upper mold.

Claims

1. A multi-field composite local continuous bulging mold for irregularly shaped variable cross-section long pipe fittings, characterized in that, The device includes an upper mold (3-1) and a lower mold (3-2), which together form an expansion cavity. A first sliding guide rail (20) is provided on the upper surface of the upper mold (3-1), and a first sliding slide rail (34) is provided on the lower surface of the lower mold (3-2). The first sliding guide rail (20) and the first sliding slide rail (34) are used for the mold to move relative to the forming machine. Both the upper mold (3-1) and the lower mold (3-2) are equipped with a water cooling system, which includes two parallel water inlet channels (13-1) and water outlet channels (13-2). The system includes several secondary channels (13-3) connecting the inlet channel (13-1) and the outlet channel (13-2), and several hydraulic valves. The inlet channel (13-1) and the outlet channel (13-2) are used to continuously supply cooling water. Each secondary channel (13-3) has a hydraulic valve on both sides. The hydraulic valve includes an input end that extends out of the mold and an output end that blocks the inlet channel (13-1) and the outlet channel (13-2). Each secondary channel (13-3) has a through hole on both sides connecting the outside and the expansion cavity. The through hole is located between the hydraulic valve and the secondary channel (13-3). A heating structure is installed inside the through hole. The heating structure is used to connect the external circuit and the long pipe (9). The heating structure is an elastic structure. When the long pipe (9) expands, the upper mold (3-1) and the lower mold (3-2) close together, and the forming machine generates sufficient closing force on the upper mold (3-1) and the lower mold (3-2). The two ends of the long pipe (9) are sealed and pressurized inert gas is introduced. Cooling water is introduced into the water inlet channel (13-1) of the upper mold (3-1) and the lower mold (3-2). The water inlet channel (13-1), the water outlet channel (13-2), and the secondary channel (13-3) form a In the circulating cooling water circuit, the hydraulic valve and heating structure are subjected to the pressure of the forming machine. The input end of the hydraulic valve is under pressure, and the output end simultaneously blocks the water inlet channel (13-1) and the water outlet channel (13-2), thereby closing the water inlet and outlet on both sides of at least one secondary channel (13-3). At least two heating structures are compressed and their ends are attached to the long pipe (9) to form a local current circuit. Both heating structures are located within the blocked water inlet channel (13-1) and water outlet channel (13-2) range, ensuring that the long pipe (9) within this range is heated to the forming temperature and produces a local bulging film.

2. The multi-field composite local continuous bulging mold for irregularly shaped cross-section long pipes according to claim 1, characterized in that, The hydraulic valve includes a T-shaped hydraulic chamber, liquid (18) disposed in the hydraulic chamber, a piston (12) disposed in the narrow part of the hydraulic chamber, movable water-blocking blocks (17) disposed at both ends of the wide part of the hydraulic chamber, and a second return spring (15). The movable water-blocking block (17) is provided with a second return spring (15) at its end. The piston rod of the piston (12) extends out of the mold. The piston rod is the input end of the hydraulic valve. The movable water-blocking block (17) is the output end of the hydraulic valve. When the piston rod is compressed by force, the liquid (18) in the hydraulic chamber pushes the movable water-blocking blocks (17) at both ends to move to both sides, thereby blocking the water inlet channel (13-1) and the water outlet channel (13-2). When the piston rod is depressurized, the second return spring (15) pushes the movable water-blocking block (17) back into the hydraulic chamber, and the liquid (18) in the hydraulic chamber pushes the piston (12) to extend the piston rod.

3. The multi-field composite local continuous bulging mold for irregularly shaped cross-section long pipes according to claim 2, characterized in that, The piston rod and the energized conductive block (7) are both fixedly provided with a movable slide. The movable slide is provided with an inclined guide surface on its side and a movable ball (19) on its top. The movable ball (19) is used to reduce the frictional resistance between the piston rod and the forming machine. The inclined guide surface is used to ensure that the piston rod or the energized conductive block (7) moves smoothly into the forming machine when the mold moves.

4. The multi-field composite local continuous bulging mold for irregularly shaped cross-section long pipes according to claim 3, characterized in that, The movable ball (19) on the top of the moving slide of the energized conductive block (7) is lubricated with conductive lubricating oil, which is made by adding conductive solid particles to the base oil.

5. The multi-field composite local continuous bulging mold for irregularly shaped variable cross-section long pipes according to claim 1, characterized in that, The heating structure includes a conductive block (7) and a heating electrode head (4). The heating electrode head (4) includes a connecting part (4-1) and a contact part (4-2). One end of the connecting part (4-1) is fixedly connected to the conductive block (7), and the other end is provided with a groove. One end of the contact part (4-2) is inserted into the groove of the connecting part (4-1), and the other end extends into the expansion cavity. One end of the conductive block (7) extends outward from the mold, and the other end is fixedly connected to the connecting part (4-1) of the heating electrode head. The heating electrode head (4) has... An elastic component (33) is provided inside the groove of the connecting part (4-1). The connecting part (4-1) and the contact part (4-2) are connected by the elastic component (33). The conductive block (7) is connected to the mold through the first return spring (6). When the conductive block (7) and the heating electrode head (4) are pressed, the elastic component (33) and the first return spring (6) are compressed. The elastic component (33) is used to increase the adhesion between the heating electrode head (4) and the long tube (9). When the pressure is removed, the elastic component (33) and the first return spring (6) return to their original state.

6. The multi-field composite local continuous bulging mold for irregularly shaped cross-section long pipes according to claim 1, characterized in that, The long pipe (9) is a continuous variable cross-section pipe that is difficult to process. The length of the long pipe (9) is greater than the maximum size of the worktable of the existing special forming machine. The material of the long pipe (9) is a difficult-to-deform alloy material, including titanium alloy and high-strength steel.

7. A multi-field composite local continuous bulging system for irregularly shaped variable cross-section long pipe fittings, characterized in that, The system includes a partially continuous bulging mold (3) for a long, irregularly shaped pipe with a variable cross-section as described in any one of claims 1 to 6, a forming machine, and a base (24). The base (24) and a base support (25) are fixedly connected. The base (24) is provided with a second sliding guide rail (26). The partially continuous bulging mold (3) is mounted on the base (24), and a first sliding rail (34) on the lower surface of the lower mold (3-2) moves along the second sliding guide rail (26) on the upper surface of the base (24). Two downward-pressed water columns (11-2) and an electrified platform (27) located between the two downward-pressed water columns (11-2) are fixed on the base (24). The downward-pressed water columns (11-2) are used to press against the input end of the hydraulic valve of the lower mold (3-2). The electrified platform (27) is located between the two downward-pressed water columns (11-2). The forming machine includes a press platform (1), a second sliding rail (32) is provided on the lower surface of the press platform (1), two upper water columns (11-1) and a pressure head located between the two upper water columns (11-1) are provided between the two upper water columns (11-1), the second sliding rail (32) cooperates with the first sliding guide rail (20), and the second sliding rail (32) moves along the first sliding guide rail (20). The upper water column (11-1) is used to abut the input end of the hydraulic valve of the upper mold (3-1), and the pressure head is used to abut the heating structure of the upper mold (3-1). The pressure head and the power platform (27) are connected to the external circuit, and a local heating circuit is formed with the long pipe (9) through the heating structure.

8. The multi-field composite local continuous bulging system for irregularly shaped variable cross-section long pipes according to claim 7, characterized in that, The pressure head includes two energized parts (2) and an insulating block (5) disposed between the two energized parts (2). The two energized parts (2) are respectively connected to the positive and negative terminals of the external circuit.

9. A bulging method using the multi-field composite local continuous bulging system for irregularly shaped variable cross-section long pipes as described in claim 7 or 8, characterized in that, Includes the following steps: Step 1: Install the upper mold with the press platform, place the long pipe to be expanded into the expansion cavity formed by the upper and lower molds, install the upper and lower molds together, and move the mold to the position corresponding to the power-conducting block of the mold on the power-conducting part of the press platform. Step 2: The press platform of the forming machine presses down, closes the mold and provides closing force, seals both ends of the long pipe and introduces pressurized gas into the long pipe, and introduces circulating cooling water into the water cooling system of the upper and lower molds. The press platform continues to press down, and the two upper and lower press water columns close the hydraulic valves on both sides of the corresponding secondary channels. The press head and the power platform press against the heating structure until the end of the heating structure is in contact with the long pipe. The press head, heating structure and local pipe of the processing area of ​​the forming machine form a current loop, the water flow loop of the processing area forms a local static state, and the remaining water flow loop continues to circulate and cool. Step 3: The temperature of the local pipe fittings in the processing area rises under the heating of electric current, the material of the pipe fittings softens, the deformation resistance decreases, and it expands under the action of internal gas pressure; Step 4: After the bulging of the processing area is completed, the mold is driven to move horizontally without removing the clamping force, so that the pressure head and the power platform of the forming machine press down on the heating structures on both sides of the next channel to carry out the bulging of the next processing area. Step 5: Repeat step 4 to process the long pipe in multiple sections until the final target pipe is completed.

10. The bulging method according to claim 9, characterized in that, The upper mold (3-1) is provided with baffles (21) on both sides, and the press platform (1) of the forming machine is provided with a lifting buckle (23). When the upper mold (3-1) and the press platform (1) are installed together, the lifting buckle (23) and the baffle (21) are connected to each other, the press platform (1) is raised, and the upper mold (3-1) is lifted by the cooperation of the lifting buckle of the press platform (1) and the baffle (21), and the long pipe (9) is taken out to achieve demolding.

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