A multi-pass cold roll forming device for thin-walled square and rectangular tubes with low stress load

Abstract

This invention discloses a multi-pass cold bending forming device for thin-walled rectangular tubes with low stress load, relating to the field of metal plastic processing technology. It aims to solve the technical problem of excessive bending stress in welds due to the influence of bending areas. The device includes a leveling component, an output end of which is connected to a progressive forming unit. A welding device is arranged at the output end of the progressive forming unit, a cooling component at the output end of the welding device, a grinding device at the output end of the cooling component, and a rectangular tube forming unit at the output end of the grinding device. The rectangular tube forming unit includes multiple forming extrusion parts, each composed of multiple forming rollers. A variable speed drive component is arranged to the side of the rectangular tube forming unit, and a tube wall cleaning component is arranged at the output end of the variable speed drive component. This invention has the advantage of concentrating the severe bending deformation at the four corners of the rectangular tube body into the weld-free base material area, significantly reducing the stress load at the weld.

Description

Technical Field

[0001] This invention relates to the field of metal plastic processing technology, and more specifically, to a multi-pass cold bending forming apparatus for thin-walled square and rectangular tubes with low stress load. Background Technology

[0002] In the field of metal plastic processing, thin-walled square and rectangular tubes are widely used in various industries such as building steel structures, machinery manufacturing, and furniture decoration due to their advantages such as high structural strength, regular cross-section, and high space utilization. At present, the cold bending forming process of thin-walled square and rectangular tubes usually adopts a standardized process of strip leveling, progressive bending into a circle, welding and sealing, cooling, grinding, and extrusion of the round tube into a square shape. This process can achieve mass production and meet the large-scale demand for pipes in the industrial field.

[0003] However, in traditional round tube extrusion to square tube stage, the forming rolls are mostly arranged symmetrically and parallelly, and the extrusion channel has a single specification design. This leads to high stress concentration at the four corner bends when the round tube is transformed into a square or rectangular tube, and the weld is easily distributed to the bending area, bearing excessive bending stress. This can easily cause quality problems such as weld cracking and tube wall wrinkling, seriously affecting the product qualification rate. In view of this, we propose a low-stress-load multi-pass cold bending forming device for thin-walled square and rectangular tubes. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-pass cold bending forming device for thin-walled square and rectangular tubes with low stress load, so as to solve the technical problem that the weld is easily affected by the bending area and suffers excessive bending stress.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a multi-pass cold bending forming device for thin-walled rectangular tubes with low stress load, comprising a leveling component, an output end of which is connected to an incremental forming unit, an output end of which is arranged a welding device, an output end of which is arranged a cooling component, an output end of which is arranged a grinding device, and an output end of which is arranged a rectangular tube forming unit; wherein, the rectangular tube forming unit comprises multiple forming extrusion parts, each forming extrusion part being composed of multiple forming rollers, the multiple forming rollers being arranged at four corners at an angle to form the bending areas at the four corners of the rectangular tube body as support points for extrusion forming; a variable speed drive component is arranged on the side of the rectangular tube forming unit. The output end of the variable speed drive assembly is equipped with a pipe wall cleaning component. The pipe wall cleaning component is connected to the rectangular tube forming unit via an air-cooling component. The variable speed drive assembly can drive the pipe wall cleaning component to perform reciprocating variable speed motion. When the pipe wall cleaning component moves towards the rectangular tube forming unit, it can grind and smooth the burrs on the surface of the rectangular tube body output by the rectangular tube forming unit, and drive the air-cooling component to air-cool multiple sets of formed extrusion parts. When the pipe wall cleaning component accelerates away from the rectangular tube forming unit, it can overcome the output speed of the rectangular tube body moving in the same direction to grind the burrs on the surface of the rectangular tube body, and drive the air-cooling component to air-cool itself.

[0006] Preferably, the rectangular tube forming unit includes a base frame, with multiple roller frames mounted on the top of the base frame. The forming rollers are rotatably arranged in the inner cavity of the roller frames. The forming rollers are coaxially connected to gears. The multiple forming rollers arranged in the same direction are also coaxially connected to sprockets. The sprockets of the multiple forming rollers arranged in the same direction are connected by chain drive. The gears of every two adjacent forming rollers are meshed. The top of the base frame also has multiple motors, and the output end of each motor is coaxially connected to one of the sprockets.

[0007] Preferably, the forming rollers are arranged in an inclined state, and the cross-section of the forming rollers forms a cross-sectional angle structure for forming the main body of the rectangular tube. An extrusion channel is formed between each two adjacent forming rollers. The extrusion channel is used to extrude the shape of the main body of the rectangular tube. Each two adjacent extrusion channels can provide support and positioning at the four corners of the rectangular tube. The aperture of the extrusion channels of the multiple sets of forming extrusion parts is gradually reduced, which is used to form a rectangular tube body by forming a multi-pass gradually changing extrusion of the round tube body.

[0008] Preferably, the variable speed drive assembly includes a second motor arranged in the inner cavity of the base frame, the output end of the second motor connected to a turntable, a swing arm movably arranged at the top of the inner cavity of the base frame, a drive arm rotatably arranged at the top of the swing arm, and the top of the drive arm movably connected to the pipe wall cleaning assembly; wherein, a drive column is connected to the side wall of the turntable, and a drive groove is opened on the side wall of the swing arm. The drive groove is a long groove structure, and the drive column is movably arranged in the drive groove. When the turntable rotates in the forward direction, the sliding motion formed by the drive column in the drive groove can drive the swing arm to form a reciprocating swing motion; when the drive column slides to the lower end of the drive groove, the rotation point of the drive column and the swing arm form a short lever arm state, which can drive the swing arm to rotate quickly with a large torque, and synchronously transmit power through the drive arm to drive the pipe wall cleaning assembly to accelerate away from the square and rectangular tube forming unit.

[0009] Preferably, the pipe wall cleaning assembly includes multiple slide rods arranged between the base frame and the roller frame, a cleaning frame slidably arranged on the slide rods, and the outer wall of the cleaning frame rotatably connected to the top of the drive arm; multiple pressure rods are movably inserted into the side wall of the cleaning frame, and a grinding head is detachably connected to the end of the pressure rod; the grinding head is arranged in the inner cavity of the cleaning frame, and a spring is arranged between the grinding head and the inner side wall of the cleaning frame, and the spring is sleeved on the outer circumference of the pressure rod; there are multiple grinding heads, two of which are arranged diagonally in the cross-section of the rectangular tube body, and the other two are arranged diagonally in the other direction of the cross-section of the rectangular tube body; the grinding surface of the grinding head has an open structure, which can fit against two adjacent surfaces and the bends of the two surfaces of the rectangular tube body; through the reciprocating linear movement of the cleaning frame, the multiple grinding heads can be driven to form a state of grinding the outer wall of the rectangular tube body without dead angles.

[0010] Preferably, a support tube is connected to the top of the cleaning frame, the inner cavity of the support tube is in communication with the inner cavity of the cleaning frame, a push-pull tube is integrally formed on the side wall of the support tube, a piston head is connected to the end of the push-pull tube, and multiple air intake channels are opened on the side wall of the piston head, which are in communication with the inner cavity of the push-pull tube. The inner cavity of the push-pull tube is in communication with the inner cavity of the support tube.

[0011] Preferably, the air-cooling assembly includes an adjustment box arranged above the roller frame, an air inlet pipe connected to the top of the adjustment box, an air storage chamber and a piston chamber arranged inside the adjustment box, one end of the air storage chamber communicating with the piston chamber through a vertical channel and the other end communicating with the piston chamber through a bent pipe; a main pipe is connected to the side wall of the piston chamber, and multiple branch pipes are connected to the output end of the main pipe, the output end of the branch pipes passing through the top of the roller frame and extending into the inner cavity of the roller frame, and the output end of the branch pipes is arranged above the multiple forming rollers.

[0012] Preferably, a cold water pipe is arranged in the inner cavity of the air storage chamber. The inlet and outlet of the cold water pipe both penetrate the side wall of the regulating box. The inlet of the cold water pipe is connected to an external water supply device, and the outlet of the cold water pipe is connected to an external water supply device through an external circulation system.

[0013] Preferably, a valve chamber is arranged at the connection between the inner cavity of the bend and the piston chamber. A one-way valve structure is arranged in the valve chamber. The one-way valve structure includes a support frame connected to the inner side wall of the valve chamber. A sealing plate is movably inserted into the side wall of the support frame. The support frame and the sealing plate are connected by a spring. Multiple guide rods are also connected to the side wall of the support frame. The sealing plate is slidably arranged on the guide rods. The sealing plate is in pressure contact with the inner side wall of the valve chamber, so that the bend and the piston chamber form a closed state. When the airflow is output from the bend, the airflow can squeeze the sealing plate into the piston chamber. When the airflow is compressed in the piston chamber, the airflow cannot squeeze the sealing plate into the inner cavity of the bend.

[0014] Preferably, a structural component with the opposite airflow direction to the one-way valve structure is arranged at the connection between the main pipe and the piston chamber, so that airflow can enter the inner cavity of the main pipe from the piston chamber; a component with the same structure as the one-way valve is arranged in the vertical channel, so that airflow can enter the piston chamber from the gas storage chamber; and a component with the same structure as the one-way valve is arranged in the inner cavity of the push-pull tube, so that airflow can enter the inner cavity of the push-pull tube from the piston chamber.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. This invention designs multiple forming rollers in a four-corner inclined arrangement, combined with a gradually narrowing extrusion channel. This reduces stress concentration inside the tube through multiple small-amplitude extrusion passes, while the inclined arrangement of the forming rollers at the four corners provides support and positioning for the bends at the four corners of the rectangular tube body. The close contact support between the forming rollers and the bends disperses locally concentrated stress during bending, preventing stress concentration at the sharp corners and thus avoiding overload. Simultaneously, as the round tube body is gradually shaped within the gradually narrowing extrusion channel, the inclined forming rollers concentrate the severe bending deformation at the four corners of the rectangular tube body into the weldless base material area. The weld, pre-positioned at the center of the plane, only needs to withstand gentle planar bending deformation, significantly reducing the stress load at the weld. This effectively solves the problem of cracking and wrinkling that easily occurs when extruding rectangular tubes due to improper weld placement and excessive bending stress in existing cold bending forming units, thus improving the forming quality and structural stability of the rectangular tube body.

[0017] 2. This invention designs a pipe wall cleaning component on the side of the rectangular tube forming unit. A variable speed drive component enables the pipe wall cleaning component to perform reciprocating linear motion. Within the cleaning frame of the pipe wall cleaning component, a spring fitted onto the outer circumference of the pressure rod generates elastic thrust, pushing the grinding head at the end of the pressure rod to always adhere to the surface of the rectangular tube body. The four grinding heads are arranged diagonally in two sets of cross-sections of the rectangular tube body. Furthermore, the open grinding surfaces of the grinding heads can adapt to the contours of adjacent surfaces and bends of the rectangular tube. During the reciprocating movement of the cleaning frame, multiple grinding heads can simultaneously cover the outer wall plane and the four corner bends of the rectangular tube body, forming a thorough grinding of the outer wall of the rectangular tube body. This effectively removes fine burrs adhering to the plane, extrusion flash at the four corner bends, and linear scratches formed by friction between the tube and the rollers during the forming process, which are easily generated on the surface of the rectangular tube body formed by the rectangular tube forming unit. This improves the appearance quality of the tube and its adaptability to subsequent processing.

[0018] 3. This invention, through the design of a variable speed drive assembly, enables the pipe wall cleaning assembly to perform reciprocating variable speed motion. During the continuous forward conveying of the extruded rectangular tube body, when the pipe wall cleaning assembly moves towards the rectangular tube forming unit, its moving speed forms a reasonable relative motion with the conveying speed of the rectangular tube body. The grinding head can grind the surface of the newly formed rectangular tube to remove surface burrs. Conversely, when the drive column slides to the lower end of the drive groove, the variable speed drive assembly drives the pipe wall cleaning assembly to accelerate away from the rectangular tube forming unit. The moving speed of the pipe wall cleaning assembly can overcome the forward conveying speed of the rectangular tube body, forming a reverse and faster relative motion. This allows the grinding head to perform more thorough secondary grinding on the surface of the rectangular tube body, especially achieving deep cleaning of areas prone to burr residue, such as the four corner bends; avoiding... This design avoids the problem of insufficient or no relative movement between the grinding head and the tube body during the return stroke of the pipe wall cleaning component when it reciprocates at a constant speed, i.e., when moving away from the rectangular tube forming unit. This is because the moving speed is similar to or slower than the forward conveying speed of the rectangular tube body, resulting in co-directional movement and causing grinding failure and the inability to remove residual burrs. It also avoids the drawback of blindly increasing the constant speed to ensure the grinding effect during the return stroke, which can easily lead to excessive relative movement between the pipe wall cleaning component and the tube body when it approaches the rectangular tube forming unit. This can cause excessive friction between the grinding head and the tube surface, which can not only accelerate the wear of the grinding head and shorten its service life, but may also scratch the surface of the rectangular tube body and damage the forming precision. The variable speed design achieves a precise balance between grinding efficiency and tube protection in different movement stages.

[0019] 4. This invention utilizes the reciprocating motion of the cleaning frame along with the variable speed drive assembly to synchronously drive the reciprocating piston motion of the push-pull tube and piston head within the piston chamber of the regulating box. When the cleaning frame moves towards the rectangular tube forming unit, the cooling airflow is diverted through the main pipe to the branch pipe, cooling the forming rolls in the inner cavity of the roller frame. When the cleaning frame moves away from the rectangular tube forming unit, the cooling airflow enters the inner cavity of the cleaning frame through the push-pull tube and support pipe, cooling the grinding head. This ensures efficient and continuous cooling. This design solves the problems of existing units where the forming rolls are prone to overheating due to continuous extrusion, and the grinding head is prone to high temperature due to friction, requiring multiple sets of independent cooling equipment, resulting in complex structures and high energy consumption. At the same time, relying on the reciprocating motion of the cleaning frame eliminates the need for independent drive components in the cooling system, simplifying the overall structure while achieving targeted cooling of key components, ensuring stable operation of the forming rolls and grinding head, and avoiding the impact of high temperature on the forming accuracy and grinding quality of the rectangular tube body. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the leveling component and progressive forming unit structure of the present invention;

[0022] Figure 3 This is a schematic diagram of the cooling assembly and grinding equipment of the present invention;

[0023] Figure 4 This is a schematic diagram of the square and rectangular tube forming unit, the speed-changing drive assembly, and the tube wall cleaning assembly of the present invention.

[0024] Figure 5 This is a schematic diagram of the extruded part structure of the present invention;

[0025] Figure 6 This is a side view of the disassembled structure of the molded extrusion part of the present invention;

[0026] Figure 7 This is a schematic diagram of the cleaning frame structure of the pipe wall cleaning assembly of the present invention;

[0027] Figure 8 This is a schematic diagram of the distribution structure of multiple grinding heads according to the present invention;

[0028] Figure 9 This is a cross-sectional view of the air-cooled component of the present invention;

[0029] Figure 10 for Figure 9 Enlarged schematic diagram of the structure at point A in the middle.

[0030] Explanation of the labels in the diagram:

[0031] 1. Leveling assembly; 2. Progressive forming unit; 3. Welding equipment; 4. Cooling assembly; 5. Grinding equipment; 6. Square and rectangular tube forming unit; 7. Variable speed drive assembly; 8. Tube wall cleaning assembly; 9. Air cooling assembly; 10. Cold-rolled strip steel; 11. Round tube body; 12. Square and rectangular tube body;

[0032] 61. Formed extrusion part; 62. Base frame; 63. Roller frame;

[0033] 611. Forming roll; 612. Gear; 613. Sprocket; 614. Chain; 615. Motor 1; 616. Extrusion channel;

[0034] 701. Motor II; 702. Turntable; 703. Drive column; 704. Swing arm; 705. Drive slot; 706. Drive arm; 801. Slide rod; 802. Cleaning frame; 803. Pressure rod; 804. Grinding head; 805. Spring I; 806. Push-pull tube; 807. Piston head; 808. Air intake channel; 809. Support tube; 901. Adjustment box; 902. Air intake pipe; 903. Air storage chamber; 904. Piston chamber; 905. Vertical channel; 906. Bend; 907. Main pipe; 908. Branch pipe; 909. Cold water pipe; 910. Support frame; 911. Sealing plate; 912. Spring II; 913. Guide rod. Detailed Implementation

[0035] like Figures 1 to 10As shown, this invention relates to a low-stress-load thin-walled square and rectangular tube multi-pass cold bending forming device, including a leveling component 1. The leveling component 1 is equipped with multiple sets of upper and lower roller structures. By adjusting the pressure and spacing between the rollers, the input cold-rolled strip steel 10 is progressively flattened to ensure that the surface flatness of the strip steel meets the requirements of subsequent forming. At the same time, it provides a stable conveying tension for the cold-rolled strip steel 10. The output end of the leveling component 1 is connected to a progressive forming unit 2. The progressive forming unit 2 is connected to the output end of the leveling component 1 and adopts a multi-pass continuous roller pressing structure. Through a set of forming rollers with gradually changing curvature, the flattened cold-rolled strip steel 10 is gradually bent into an open curved surface semi-finished product. Each pass of the rollers only achieves small deformation, reducing the internal stress concentration of the raw material, until the cold-rolled strip steel 10... The closed loop is shaped into a circular tube body 11. The output end of the progressive forming unit 2 is equipped with a welding device 3, which uses high-frequency induction welding technology. When the curved strip steel passes through the unit and gradually closes to form a circular tube gap, the welding device 3 locally heats the gap at high temperature, causing the edge of the strip steel to melt and cool rapidly to form a sealed circular tube body 11. The output end of the welding device 3 is equipped with a cooling component 4, which uniformly cools the high-temperature circular tube body 11 through water-cooled spraying, so that the weld and the entire pipe are rapidly cooled to room temperature. The output end of the cooling component 4 is equipped with a grinding device 5, which is used to clean the weld protrusions of the circular tube body 11 to ensure that the weld surface is flat. The output end of the grinding device 5 is equipped with a rectangular tube forming unit 6.

[0036] In an embodiment of the present invention, a variable speed drive assembly 7 is arranged on the side of the rectangular tube forming unit 6, and a tube wall cleaning assembly 8 is arranged at the output end of the variable speed drive assembly 7. The tube wall cleaning assembly 8 is connected to the rectangular tube forming unit 6 through an air-cooling assembly 9. The variable speed drive assembly 7 can drive the tube wall cleaning assembly 8 to perform reciprocating variable speed motion. When the tube wall cleaning assembly 8 moves toward the rectangular tube forming unit 6, it can grind and smooth the burrs on the surface of the rectangular tube body 12 output by the rectangular tube forming unit 6, and drive the air-cooling assembly 9 to air-cool the multi-group forming extrusion parts 61. When the tube wall cleaning assembly 8 accelerates away from the rectangular tube forming unit 6, it can overcome the output speed of the rectangular tube body 12 moving in the same direction to grind the burrs on the surface of the rectangular tube body 12, and drive the air-cooling assembly 9 to air-cool itself.

[0037] In an embodiment of the present invention, the rectangular tube forming unit 6 includes multiple forming extrusion parts 61, each forming extrusion part 61 being composed of multiple forming rollers 611. The multiple forming rollers 611 are arranged at four corners at an angle, forming the bending areas at the four corners of the rectangular tube body 12 as support points for extrusion forming. The rectangular tube forming unit 6 includes a base frame 62, and multiple roller frames 63 are installed on the top of the base frame 62. The forming rollers 611 are rotatably arranged in the inner cavity of the roller frames 63. The forming rollers 611 are coaxially connected to gears 612. The multiple forming rollers 611 arranged in the same direction are also coaxially connected to sprockets 613. The sprockets 613 of the multiple forming rollers 611 arranged in the same direction are connected by a chain 614. The gears 612 of each two adjacent forming rollers 611 are meshed. Multiple motors 615 are also arranged on the top of the base frame 62. The output end of the motor 615 is coaxially connected to one of the sprockets 613. The forming rolls 611 are arranged in an inclined state. The cross-section of the forming rolls 611 forms a cross-sectional angle structure for forming the rectangular tube body 12. An extrusion channel 616 is formed between each two adjacent forming rolls 611. The extrusion channel 616 is used to extrude the shape of the rectangular tube body 12. Each two adjacent extrusion channels 616 can provide support and positioning at the four corners of the rectangular tube body 12. The aperture of the extrusion channel 616 of the multi-component forming extrusion part 61 is gradually narrowed, which is used to form the rectangular tube body 12 by forming a multi-pass gradually changing extrusion of the round tube body 11. After the motor 615 starts, it drives the sprocket 613, which is coaxial with it, to rotate through the output end. The sprocket 613 drives multiple forming rollers 611 arranged in the same direction to rotate synchronously through the chain 614. At the same time, adjacent forming rollers 611 rotate synchronously through the gears 612 connected coaxially. After the round tube body 11 enters the extrusion channel 616 of the multi-component forming extrusion part 61, because the forming rollers 611 are arranged at four corners with an inclined cross-section and the cross-section is adapted to the angle structure of the rectangular tube body 12, the adjacent extrusion channels 616 provide support and positioning at the four corners of the rectangular tube body 12. In addition, the diameter of the extrusion channel 616 of the multi-component forming extrusion part 61 is gradually narrowed. The round tube body 11 is gradually shaped into the rectangular tube body 12 through multiple passes of gradual extrusion.

[0038] This invention designs multiple forming rollers 611 in a four-corner inclined arrangement, combined with the gradually narrowing extrusion channel 616. This reduces stress concentration inside the tube through multiple small-amplitude extrusions, and the four-corner inclined arrangement of the forming rollers 611 provides support and positioning at the four corners of the rectangular tube body 12. The close contact support between the forming rollers 611 and the tube bends disperses locally concentrated stress during bending, preventing stress concentration at the sharp corners and thus avoiding overload. Simultaneously, when the round tube body 1... 1. During the gradual shaping process within the tapered extrusion channel 616, the forming rollers arranged at the four corners will concentrate the severe bending deformation of the four corners of the rectangular tube body 12 into the base material area without welds. The weld, which is pre-positioned at the center of the plane, only needs to withstand gentle planar bending deformation, which greatly reduces the stress load at the weld. This effectively solves the problem that existing cold bending forming units are prone to cracking and wrinkling when extruding into rectangular tubes due to improper weld position and excessive bending stress, thus improving the forming quality and structural stability of the rectangular tube body 12.

[0039] In an embodiment of the present invention, the transmission drive assembly 7 includes a second motor 701 disposed in the inner cavity of the base frame 62. The output end of the second motor 701 is connected to a turntable 702. A swing arm 704 is movably disposed at the top of the inner cavity of the base frame 62, and a drive arm 706 is rotatably disposed at the top of the swing arm 704. The top of the drive arm 706 is movably connected to the pipe wall cleaning assembly 8. A drive column 703 is connected to the side wall of the turntable 702, and a drive groove 705 is formed on the side wall of the swing arm 704. The drive groove 705 is a long, narrow groove structure. The drive column 703 is movably disposed within the drive groove 705. When the transmission drive assembly 7 is working, the second motor 701 in the inner cavity of the base frame 62 starts and drives the turntable 702 to rotate forward. The drive column 703 connected to the side wall of the turntable 702 rotates synchronously with the turntable. Since the drive column 703 is movably embedded in the long, narrow drive groove 705 on the side wall of the swing arm 704, the drive column 703... 3. During the rotation, it will slide in the drive groove 705, thereby driving the swing arm 704 to swing back and forth with its connection point with the base frame 62 as the axis. When the drive column 703 slides to the lower end of the drive groove 705, the rotation point of the drive column 703 and the swing arm 704 forms a short lever arm state. With the output torque of the motor 701 remaining unchanged, the short lever arm can be converted into a larger torque to drive the swing arm 704 to rotate quickly. The top of the swing arm 704 transmits power synchronously to the pipe wall cleaning component 8 through the drive arm 706 connected by rotation. Finally, the pipe wall cleaning component 8 accelerates its movement away from the square and rectangular tube forming unit 6. When the drive column 703 slides to other areas of the drive groove 705, the swing speed of the swing arm 704 slows down. With the help of the drive arm 706, the pipe wall cleaning component 8 completes the movement closer to the square and rectangular tube forming unit 6, thereby realizing the reciprocating speed change motion of the pipe wall cleaning component 8.

[0040] In an embodiment of the present invention, the pipe wall cleaning assembly 8 includes a plurality of slide rods 801 arranged between the base frame 62 and the roller frame 63. A cleaning frame 802 is slidably arranged on the slide rods 801. The outer wall of the cleaning frame 802 is rotatably connected to the top of the drive arm 706. A plurality of pressure rods 803 are movably inserted into the side wall of the cleaning frame 802. A grinding head 804 is detachably connected to the end of the pressure rod 803. The grinding head 804 is arranged in the inner cavity of the cleaning frame 802, and a spring 805 is arranged between the grinding head 804 and the inner side wall of the cleaning frame 802. The grinding head 804 is sleeved on the outer circumference of the pressure rod 803. There are multiple grinding heads 804, two of which are arranged diagonally on the cross-section of the rectangular tube body 12, and the other two are arranged diagonally on the other side of the cross-section of the rectangular tube body 12. The grinding surface of the grinding head 804 is an open structure that can fit into the two adjacent surfaces and the bends of the two surfaces of the rectangular tube body 12. Through the reciprocating linear movement of the cleaning frame 802, the multiple grinding heads 804 can be driven to form a state of grinding the outer wall of the rectangular tube body 12 without dead angles. Driven by the drive arm 706 of the transmission drive assembly 7, the cleaning frame 802 reciprocates linearly along the slide rod 801. Inside the cleaning frame 802, the spring 805, sleeved on the outer circumference of the pressure rod 803, generates an elastic thrust, pushing the grinding head 804 at the end of the pressure rod 803 to always be in contact with the surface of the rectangular tube body 12. The four grinding heads 804 are arranged in two diagonal positions on the cross-section of the rectangular tube body 12. In addition, the open grinding surface of the grinding head 804 can be adapted to the adjacent two surfaces and bends of the rectangular tube. The contour of the tube allows multiple grinding heads 804 to simultaneously cover the outer wall plane and the four corner bending areas of the rectangular tube body 12 during the reciprocating movement of the cleaning frame 802. This results in thorough grinding of the outer wall of the rectangular tube body 12 without any dead angles, effectively removing the fine burrs that are easily generated on the surface of the rectangular tube body 12 extruded by the rectangular tube forming unit 6, the extrusion flash at the four corner bending areas, and the linear scratches formed by the friction between the tube and the rollers during the forming process. This improves the appearance quality of the tube and its adaptability to subsequent processing.

[0041] This invention designs a variable speed drive assembly 7 to drive the tube wall cleaning assembly 8 in reciprocating variable speed motion. During the continuous forward conveying of the extruded rectangular tube body 12, when the tube wall cleaning assembly 8 moves towards the rectangular tube forming unit 6, its moving speed forms a reasonable relative motion with the conveying speed of the rectangular tube body 12. The grinding head 804 can grind the surface of the newly formed rectangular tube to remove surface burrs. When the drive column 703 slides to the lower end of the drive groove 705, the variable speed drive assembly 7 drives the tube wall cleaning assembly 8 to accelerate away from the rectangular tube forming unit 6. The moving speed of the tube wall cleaning assembly 8 can overcome the forward conveying speed of the rectangular tube body 12, forming a reverse and faster relative motion. This allows the grinding head 804 to perform more thorough secondary grinding on the surface of the rectangular tube body 12, especially achieving deeper grinding in areas prone to burr residue, such as the four corner bends. The cleaning process avoids the problem of insufficient or no relative movement between the grinding head 804 and the rectangular tube body 12 during the return stroke when the pipe wall cleaning component 8 is moving away from the rectangular tube forming unit 6, as the moving speed is similar to or slower than the forward conveying speed of the rectangular tube body 12. This results in grinding failure and the inability to remove residual burrs. It also avoids the problem of blindly increasing the uniform speed to ensure the grinding effect during the return stroke, which can easily lead to excessive relative movement between the pipe wall cleaning component 8 and the rectangular tube body 12 when the pipe wall cleaning component 8 approaches the rectangular tube forming unit 6. This can cause excessive friction between the grinding head 804 and the tube surface, which can not only accelerate the wear of the grinding head and shorten its service life, but also scratch the surface of the rectangular tube body 12 and damage the forming accuracy. The variable speed design achieves a precise balance between grinding efficiency and tube protection in different movement stages.

[0042] In another embodiment of the present invention, a support tube 809 is connected to the top of the cleaning frame 802. The inner cavity of the support tube 809 is in communication with the inner cavity of the cleaning frame 802. A push-pull tube 806 is integrally formed on the side wall of the support tube 809. A piston head 807 is connected to the end of the push-pull tube 806. A plurality of air intake channels 808 are opened on the side wall of the piston head 807, which are in communication with the inner cavity of the push-pull tube 806. The inner cavity of the push-pull tube 806 is in communication with the inner cavity of the support tube 809. The air-cooled assembly 9 includes an adjustment box 901 arranged above the roller frame 63. An air inlet pipe 902 is connected to the top of the adjustment box 901. An air storage chamber 903 and a piston chamber 904 are arranged inside the adjustment box 901. One end of the air storage chamber 903 is connected to the piston chamber 904 through a vertical channel 905, and the other end is connected to the piston chamber 904 through a bend pipe 906. A main pipe 907 is connected to the side wall of the piston chamber 904. Multiple branch pipes 908 are connected to the output end of the main pipe 907. The output end of the branch pipes 908 passes through the top of the roller frame 63 and extends into the inner cavity of the roller frame 63. The output end of the branch pipes 908 is arranged above the multiple forming rollers 611. The air storage chamber 903 is equipped with a cold water pipe 909. The inlet and outlet of the cold water pipe 909 both penetrate the side wall of the regulating box 901. The inlet of the cold water pipe 909 is connected to the external water supply equipment, and the outlet of the cold water pipe 909 is connected to the external water supply equipment through the external circulation system to form a water-cooled circulation system.

[0043] Furthermore, a valve chamber is arranged at the connection between the inner cavity of the bend 906 and the piston chamber 904. A one-way valve structure is arranged in the valve chamber. The one-way valve structure includes a support frame 910 connected to the inner side wall of the valve chamber. A sealing plate 911 is movably inserted into the side wall of the support frame 910. The support frame 910 and the sealing plate 911 are connected by a spring 912. Multiple guide rods 913 are also connected to the side wall of the support frame 910. The sealing plate 911 is slidably arranged on the guide rods 913. The sealing plate 911 is pressed against the inner side wall of the valve chamber, so that the bend 906 and the piston chamber 904 form a closed state. When the airflow is output from the bend 906, the airflow can squeeze the sealing plate 911 into the piston chamber 904. When the airflow is compressed in the piston chamber 904, the airflow cannot squeeze the sealing plate 911 into the inner cavity of the bend 906. At the connection between the main pipe 907 and the piston chamber 904, a structural component is arranged in the opposite direction of airflow to the one-way valve structure, so that airflow can enter the inner cavity of the main pipe 907 from the piston chamber 904; a component with the same structure as the one-way valve is arranged in the vertical channel 905, so that airflow can enter the piston chamber 904 from the gas storage chamber 903; a component with the same structure as the one-way valve is arranged in the inner cavity of the push-pull tube 806, so that airflow can enter the inner cavity of the push-pull tube 806 from the piston chamber 904.

[0044] The external water supply equipment delivers cold water through the inlet of the cold water pipe 909. The cold water flows in the cold water pipe 909 within the gas storage chamber 903, and then flows back to the water supply equipment through the outlet and the external circulation system to form a water-cooled circulation, cooling the gas supplied by the air inlet pipe 902 in the gas storage chamber 903. At the same time, when the cleaning rack 802 moves back and forth with the speed-shifting drive assembly 7, it drives the support pipe 809 and the push-pull pipe 806 to move synchronously, causing the piston head 807 to reciprocate within the piston chamber 904. Piston movement; when the cleaning frame 802 moves towards the rectangular tube forming unit 6, the piston head 807 compresses the gas in the piston chamber 904 in front. At this time, the sealing plate 911 of the one-way valve at the bend 906 remains closed under the action of the spring 912, and the airflow cannot enter the bend 906 in the reverse direction. Meanwhile, the reverse one-way valve at the main pipe 907 opens, and the cooled gas is diverted through the main pipe 907 to the branch pipe 908, and finally blown onto the forming roll 611 in the inner cavity of the roll frame 63 to achieve air cooling. At the same time, the piston head 807... A negative pressure is created in the piston chamber 904 behind 07, causing the one-way valve in the vertical channel 905 to open. Cooling gas in the gas storage chamber 903 is then supplied to the piston chamber 904 through the vertical channel 905. When the cleaning frame 802 moves away from the square and rectangular tube forming unit 6, the piston head 807 moves back synchronously. At this time, a negative pressure is created in the piston chamber 904 in front of the piston head 807, causing the one-way valve at the bend 906 to open, allowing the cold gas in the gas storage chamber 903 to flow through the bend 906. The cooling gas enters the piston chamber 904 to replenish the cooling system. When the piston head 807 moves back synchronously, the cooling gas behind the piston head 807 is compressed, causing the one-way valve inside the push-pull tube 806 to open. The cooling gas in the piston chamber 904 enters the cleaning frame 802 through the push-pull tube 806 and the support tube 809, thereby cooling the grinding head 804 inside the cleaning frame 802. The reciprocating motion of the cleaning frame enables the alternating switching of the air-cooled object, and the cold water pipe 909 continuously cools the airflow, improving the cooling effect.

[0045] This invention utilizes the reciprocating motion of the cleaning frame 802 along with the speed-changing drive assembly 7, which synchronously drives the reciprocating piston motion generated by the push-pull tube 806 and the piston head 807 within the piston chamber 904 of the regulating box 901. When the cleaning frame 802 moves towards the rectangular tube forming unit 6, the cooling airflow is diverted through the main pipe 907 to the branch pipe 908, cooling the forming roll 611 inside the roller frame 63. When the cleaning frame 802 moves away from the rectangular tube forming unit 6, the cooling airflow enters the inner cavity of the cleaning frame 802 through the push-pull tube 806 and the support tube 809, further cooling the forming roll 611. The grinding head 804 is cooled down; ensuring efficient and continuous cooling, this design solves the problems of existing units where the forming roll 611 is prone to overheating due to continuous extrusion and the grinding head 804 is prone to high temperature due to friction, and multiple independent cooling devices are required, resulting in complex structure and high energy consumption. At the same time, relying on the reciprocating motion of the cleaning frame 802, the independent drive component of the cooling system is eliminated, simplifying the overall structure while achieving targeted cooling of key components, ensuring stable operation of the forming roll 611 and the grinding head 804, and avoiding the impact of high temperature on the forming accuracy and grinding quality of the square and rectangular tube body 12.

[0046] Working Principle: This embodiment provides a multi-pass cold bending forming device for thin-walled square and rectangular tubes with low stress load. During use, cold-rolled strip steel 10 is fed into a leveling assembly 1. The leveling assembly 1 ensures the flatness of the strip surface meets the standard through multiple sets of upper and lower rollers, while providing stable conveying tension. The flattened cold-rolled strip steel 10 is then fed to an incremental forming unit 2. The incremental forming unit 2 uses a set of forming rollers with gradually changing curvature to progressively bend the cold-rolled strip steel 10 into an open curved surface. After multiple passes of small deformation, a circular tube body 11 is formed. The circular tube body 11 is output from the incremental forming unit 2 to a welding device 3, where it is welded to form a sealed circular tube body 11. The welded circular tube body 11 then enters a cold... The cooling component 4 cools the entire tube body 11 to room temperature. The cooled tube body 11 is then conveyed to the grinding equipment 5, which cleans the weld protrusions on the surface of the tube body 11 to ensure a smooth weld. Subsequently, the tube body 11 enters the rectangular tube forming unit 6. The motor 615 of the rectangular tube forming unit 6 starts, driving the coaxial sprocket 613 to rotate. Through the chain 614, multiple forming rollers 611 arranged in the same direction rotate synchronously, and adjacent forming rollers 611 rotate collaboratively through gear 612 meshing. The extrusion channel 616 of the multi-component forming extrusion part 61 gradually narrows, working in conjunction with the forming rollers 611 arranged at the four corners to perform multiple passes on the tube body 11. Gradual extrusion pre-positions the weld seam at the center of the rectangular tube plane, while the intense bending deformation at the four corners concentrates in the base material area, gradually shaping the round tube body 11 into the rectangular tube body 12. During the forming process of the rectangular tube body 12, the variable speed drive assembly 7 works synchronously. The motor 701 drives the turntable 702 to rotate, and the drive column 703 on the side wall of the turntable 702 rotates with the turntable 702 and slides in the drive groove 705 of the swing arm 704, causing the swing arm 704 to swing back and forth around the connection point with the base frame 62. The top of the swing arm 704 drives the tube wall cleaning assembly 8 to reciprocate along the slide bar 801 via the drive arm 706. When the tube wall cleaning assembly 8 moves towards the rectangular tube forming unit 6... At the same time, the grinding head 804 in the inner cavity of the cleaning frame 802 is in contact with the surface of the square and rectangular tube body 12 to grind the burrs on the surface of the newly formed square and rectangular tube body 12; at the same time, the cleaning frame 802 drives the support tube 809 and the push-pull tube 806 to move, so that the piston head 807 is pushed forward in the piston chamber 904. The gas in the gas storage chamber 903, which is cooled by the cold water pipe 909, enters the piston head 807 in the piston chamber 904 through the vertical channel 905. The cooling in front of the piston head 807 is compressed and diverted to the branch pipe 908 through the main pipe 907. The branch pipe 908 delivers the cooling airflow to the forming rolls 611 in the inner cavity of the roll frame 63 to cool the forming rolls 611.When the drive column 703 slides to the lower end of the drive groove 705, the drive column 703 and the rotation point of the swing arm 704 form a short lever arm, driving the swing arm 704 to rotate rapidly. Through the drive arm 706, the tube wall cleaning assembly 8 accelerates away from the rectangular tube forming unit 6. At this time, the moving speed of the grinding head 804 can overcome the forward conveying speed of the rectangular tube body 12, forming a reverse and faster relative motion, grinding and cleaning the stubborn burrs remaining on the surface of the rectangular tube body 12 and at the four corner bends; at the same time, the cleaning frame 802 drives the piston head 807 to move back in the reverse direction in the piston chamber 904, forming a negative pressure in front of the piston head 807, causing the one-way valve in the bend 906 to open, storing... Cooling gas in the air chamber 903 is supplied to the piston chamber 904 via the bend 906. Meanwhile, the cooling gas behind the piston head 807 is compressed, pushing open the one-way valve inside the push-pull tube 806, entering the support tube 809 through the push-pull tube 806, and finally being delivered to the cleaning frame 802 for air cooling of the high-speed friction-heated grinding head 804. After deep grinding and cooling are completed, as the drive column 703 continues to slide within the drive groove 705, the tube wall cleaning assembly 8 switches back to moving towards the rectangular tube forming unit 6, cyclically completing the surface cleaning and equipment cooling operations of the rectangular tube body 12, ultimately outputting a thin-walled rectangular tube with a smooth surface and meeting forming quality standards.

[0047] The embodiments disclosed in this invention are preferred embodiments, but are not limited thereto. Those skilled in the art can easily understand the spirit of this invention based on the above embodiments and make different extensions and variations, but as long as they do not depart from the spirit of this invention, they are all within the protection scope of this invention.

Claims

1. A multi-pass cold bending forming device for thin-walled square and rectangular tubes with low stress load, characterized in that, The system includes a leveling component (1), the output end of which is connected to a progressive forming machine (2), the output end of which is equipped with a welding device (3), the output end of which is equipped with a cooling component (4), the output end of which is equipped with a grinding device (5), and the output end of which is equipped with a square and rectangular tube forming machine (6). The rectangular tube forming unit (6) includes multiple forming extrusion parts (61). Each forming extrusion part (61) is composed of multiple forming rollers (611). The multiple forming rollers (611) are arranged at four corners to form a support point for extrusion forming of the bending area at the four corners of the rectangular tube body (12). The rectangular tube forming unit (6) also includes a base frame (62), on the top of which are multiple roller frames (63), and the forming rollers (611) are rotatably arranged in the inner cavity of the roller frames (63); The rectangular tube forming machine (6) is provided with a speed-changing drive assembly (7) on its side. The output end of the speed-changing drive assembly (7) is provided with a tube wall cleaning assembly (8). The tube wall cleaning assembly (8) is connected to the rectangular tube forming machine (6) through an air-cooling assembly (9). The variable speed drive assembly (7) includes a second motor (701) arranged in the inner cavity of the base frame (62), the output end of the second motor (701) is connected to a turntable (702), a swing arm (704) is movably arranged at the top of the inner cavity of the base frame (62), a drive arm (706) is rotatably arranged at the top of the swing arm (704), and the top of the drive arm (706) is movably connected to the pipe wall cleaning assembly (8). The pipe wall cleaning assembly (8) includes a plurality of slide rods (801) arranged between the base frame (62) and the roller frame (63), and a cleaning frame (802) is slidably arranged on the slide rods (801). The outer side wall of the cleaning frame (802) is rotatably connected to the top of the drive arm (706). The cleaning frame (802) has multiple pressure rods (803) movably inserted into its side wall, and the end of each pressure rod (803) is detachably connected to a grinding head (804). The variable speed drive assembly (7) can drive the pipe wall cleaning assembly (8) to perform reciprocating variable speed motion; when the pipe wall cleaning assembly (8) moves towards the rectangular tube forming machine (6), it can grind and smooth the burrs on the surface of the rectangular tube body (12) output by the rectangular tube forming machine (6), and drive the air cooling assembly (9) to air cool multiple sets of forming extrusion parts (61); when the pipe wall cleaning assembly (8) accelerates away from the rectangular tube forming machine (6), the pipe wall cleaning assembly (8) can overcome the output speed of the rectangular tube body (12) moving in the same direction to form a grinding operation on the surface of the rectangular tube body (12), and drive the air cooling assembly (9) to air cool itself.

2. The low-stress-load thin-walled square and rectangular tube multi-pass cold bending forming device according to claim 1, characterized in that, The forming roll (611) is coaxially connected to a gear (612), and the multiple forming rolls (611) arranged in the same direction are also coaxially connected to sprockets (613). The sprockets (613) of the multiple forming rolls (611) arranged in the same direction are connected by a chain (614). The gears (612) of each two adjacent forming rolls (611) are meshed. The top of the base frame (62) is also equipped with multiple motors (615), and the output end of the motor (615) is coaxially connected to one of the sprockets (613).

3. The low-stress-load thin-walled square and rectangular tube multi-pass cold bending forming device according to claim 2, characterized in that, The forming rollers (611) are arranged in an inclined state. The cross section of the forming rollers (611) forms a cross-sectional angle structure for forming the rectangular tube body (12). An extrusion channel (616) is formed between each two adjacent forming rollers (611). The extrusion channel (616) is used to extrude the shape of the rectangular tube body (12). Each two adjacent extrusion channels (616) can provide support and positioning at the four corners of the rectangular tube body (12). The aperture of the extrusion channel (616) of the multiple sets of forming extrusion parts (61) is gradually reduced, which is used to form a multi-pass gradually changing extrusion of the round tube body (11) to form the shape of the rectangular tube body (12).

4. The low-stress-load thin-walled square and rectangular tube multi-pass cold bending forming device according to claim 2, characterized in that, The turntable (702) has a drive column (703) connected to its side wall, and the swing arm (704) has a drive groove (705) on its side wall. The drive groove (705) is a long groove structure. The drive column (703) is movably arranged in the drive groove (705). When the turntable (702) rotates in the forward direction, the drive column (703) can slide in the drive groove (705) to drive the swing arm (704) to form a reciprocating swing motion. When the drive column (703) slides to the lower end of the drive groove (705), the rotation point of the drive column (703) and the swing arm (704) form a short lever arm state, which can drive the swing arm (704) to rotate quickly and transmit power synchronously through the drive arm (706) to drive the pipe wall cleaning assembly (8) to accelerate and move away from the square and rectangular tube forming unit (6).

5. The low-stress-load thin-walled square and rectangular tube multi-pass cold bending forming device according to claim 4, characterized in that, The grinding head (804) is arranged in the inner cavity of the cleaning frame (802), and a spring (805) is arranged between the grinding head (804) and the inner side wall of the cleaning frame (802). The spring (805) is sleeved on the outer circumference of the pressure rod (803). There are multiple grinding heads (804), two of which are arranged diagonally across the cross-section of the rectangular tube body (12), and the other two are arranged diagonally across the cross-section of the rectangular tube body (12). The grinding surface of the grinding head (804) is an open structure that can fit the two adjacent surfaces and the bends of the two surfaces of the rectangular tube body (12). Through the reciprocating linear movement of the cleaning frame (802), multiple grinding heads (804) can be driven to form a state of grinding the outer side wall of the rectangular tube body (12) without dead angles.

6. The low-stress-load thin-walled square and rectangular tube multi-pass cold bending forming device according to claim 5, characterized in that, The top of the cleaning rack (802) is connected to a support tube (809). The inner cavity of the support tube (809) is in communication with the inner cavity of the cleaning rack (802). The side wall of the support tube (809) is integrally formed with a push-pull tube (806). The end of the push-pull tube (806) is connected to a piston head (807). The side wall of the piston head (807) has multiple air intake channels (808) that communicate with the inner cavity of the push-pull tube (806). The inner cavity of the push-pull tube (806) is in communication with the inner cavity of the support tube (809).

7. The low-stress-load thin-walled square and rectangular tube multi-pass cold bending forming device according to claim 6, characterized in that, The air-cooling assembly (9) includes an adjustment box (901) arranged above the roller frame (63). An air inlet pipe (902) is connected to the top of the adjustment box (901). An air storage chamber (903) and a piston chamber (904) are arranged inside the adjustment box (901). One end of the air storage chamber (903) is connected to the piston chamber (904) through a vertical channel (905), and the other end is connected to the piston chamber (904) through a bend pipe (906). A main pipe (907) is connected to the side wall of the piston chamber (904). A plurality of branch pipes (908) are connected to the output end of the main pipe (907). The output end of the branch pipes (908) passes through the top of the roller frame (63) and extends to the inner cavity of the roller frame (63). The output end of the branch pipes (908) is arranged above the plurality of forming rolls (611).

8. The low-stress-load thin-walled square and rectangular tube multi-pass cold bending forming device according to claim 7, characterized in that, The air storage chamber (903) is equipped with a cold water pipe (909). The inlet and outlet of the cold water pipe (909) both penetrate the side wall of the regulating box (901). The inlet of the cold water pipe (909) is connected to an external water supply device, and the outlet of the cold water pipe (909) is connected to an external water supply device through an external circulation system.

9. The low-stress-load thin-walled square and rectangular tube multi-pass cold bending forming device according to claim 8, characterized in that, A valve chamber is arranged at the connection between the inner cavity of the bend (906) and the piston chamber (904). A one-way valve structure is arranged in the valve chamber. The one-way valve structure includes a support frame (910) connected to the inner side wall of the valve chamber. A sealing plate (911) is movably inserted into the side wall of the support frame (910). The support frame (910) and the sealing plate (911) are connected by a spring (912). A plurality of guide rods (913) are also connected to the side wall of the support frame (910). The sealing plate (911) 11) Sliding arrangement on the guide rod (913), the sealing plate (911) is pressed against the inner wall of the valve chamber, so that the bend (906) and the piston chamber (904) form a closed state. When the airflow is output from the bend (906), the airflow can squeeze the sealing plate (911) into the piston chamber (904). When the airflow is compressed in the piston chamber (904), the airflow cannot squeeze the sealing plate (911) into the inner cavity of the bend (906).

10. The low-stress-load thin-walled square and rectangular tube multi-pass cold bending forming device according to claim 9, characterized in that, At the connection between the main pipe (907) and the piston chamber (904), a structural component is arranged in the opposite direction of airflow to the one-way valve structure, so that airflow can enter the inner cavity of the main pipe (907) from the piston chamber (904); the vertical channel (905) is arranged with a component identical to the one-way valve structure, so that airflow can enter the piston chamber (904) from the gas storage chamber (903); the inner cavity of the push-pull tube (806) is arranged with a component identical to the one-way valve structure, so that airflow can enter the inner cavity of the push-pull tube (806) from the piston chamber (904).

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