A method for improving leg pipe bending accuracy

Abstract

The present invention discloses a method for improving the bending accuracy of leg pipes, comprising the following steps: S1: adjusting the positioning clappers on both sides to a discharging state; making the center positions of the two positioning clappers coincide with the center position of a bending arm device; S2: placing one or more steel pipes between the two positioning clappers; S3: controlling the positioning clappers on both sides to synchronously move toward each other to strike the steel pipes; the positioning clappers move closer to clamp the maximum length steel pipe; at the same time, the shorter length steel pipe that is not clamped will be offset between the two positioning clappers by the striking action of the positioning clappers on either side, and finally, when the movement stops, the center position of the shorter length steel pipe itself coincides with the center position between the two positioning clappers, or the center position of the shorter length steel pipe itself offsets and approaches the center position between the two positioning clappers; S4: the bending arm device located at the center of the two positioning clappers performs a bending operation on the one or more steel pipes.

Description

Technical Field

[0001] The present invention relates to the field of leg pipe processing, and in particular to a method for improving the bending accuracy of leg pipes. Background Art

[0002] The legs of an existing type of leisure chair are made of metal round tubes. During the processing and production of the chair legs, the raw material hollow steel tubes usually need to be cut into sections, and then the cut steel tubes are bent at both ends by a pipe bending machine to obtain U-shaped steel tubes for use as the legs of the leisure chair.

[0003] As can be seen from the above, as a U-shaped leg tube, in order to ensure the stability of the chair, the lengths of the two opposite legs of the same U-shaped steel tube must be as identical as possible to prevent the chair from shaking during use. However, the pipe precision of existing conventional pipe bending machines is not high, which usually results in large errors during bending, resulting in low precision; specifically, when bending steel pipes, existing pipe bending machines often use horizontally spaced push blocks and positioning supports to position the two ends of the steel pipe, and then bend the steel pipe through the bending arm in the center of the pipe bending machine. The push block is movable, and the positioning support is fixed; that is, it is a one-sided support, and the push block moves toward the positioning support to push the steel pipe so that the steel pipe is clamped between the push block and the positioning support; and, when bending, the end face of the positioning support is set as the reference, that is, the distance between the bending arm device of the pipe bending machine and the end face of the positioning support is initially set to be fixed.

[0004] However, steel pipes are uniformly cut before bending. During the actual cutting process, it is impossible to ensure that each section of steel pipe is cut to the same length, and a length error of several millimeters is inevitable. This results in some steel pipes being bent longer than standard steel pipes, while others are shorter. Since the aforementioned prior art uses the end face of the positioning support as a reference during positioning, during the actual bending operation, only the distance between the end of the steel pipe closest to the positioning support and the bending arm remains unchanged, while the distance between the other end of the steel pipe and the bending arm may vary due to the length error of the steel pipe itself. In short, the length error of the steel pipe itself is concentrated on one end of the steel pipe, resulting in one leg of the U-shaped leg being longer than the other. For example, for a standard 130mm steel pipe, the ideal length of each U-shaped leg after bending is 50mm. However, due to the pipe's inherent length error, a 134mm steel pipe might have legs that are 50mm and 54mm long after bending. Alternatively, a 126mm steel pipe might have legs that are 50mm and 46mm long after bending. This means that the pipe's inherent length error is concentrated on one leg of the U-shaped leg. Based on this example, the length difference between the two legs of the same U-shaped leg is 4mm.

[0005] Although errors are unavoidable during processing, if the error between the lengths of the two ends of the U-shaped legs is small (for example, less than 2mm), that is, 2mm is the allowable error, then even if there is a height error, the legs are supported on the ground and deform, and the human body cannot feel the existence of this error, which does not affect the use of the legs. However, if the error is large, the length difference between the two legs of the U-shaped steel pipe will also be large. For example, the example in the above paragraph has reached 4mm, which exceeds the allowable error, making the processed legs unusable. In the above-mentioned existing steel pipe bending technology, whether the steel pipe is qualified after bending depends entirely on the error during the steel pipe cutting. That is, the length error of the steel pipe during cutting will be fully reflected during bending; it is impossible to avoid errors or reduce some errors to improve accuracy, which undoubtedly makes the operation very restrictive.

[0006] Therefore, it is necessary to improve the above-mentioned defects and provide a method that can further improve the bending accuracy of the leg pipes to solve the above-mentioned technical problems. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies existing in the above-mentioned prior art and provide a method for improving the bending accuracy of leg pipes; the positioning clasps on both sides are used to move simultaneously to position the middle steel pipe, and the center position of the two positioning clasps is used as a reference during the positioning process, so that the positioning clasps can clamp the maximum length steel pipe, so that the center position of the maximum length steel pipe coincides with the center position of the two positioning clasps; and the positioning clasps can also act on shorter length steel pipes, so that the center position of the shorter length steel pipe itself is close to or coincides with the center position between the two positioning clasps; the positioning effect is better; and then when the bending arm device bends the steel pipe, the length error of the steel pipe itself will be dispersed at both ends of the steel pipe, and the length deviation between the two legs of the U-shaped steel pipe formed by the bending is very small, kept within the allowable error range, thereby improving the accuracy.

[0008] The technical solution of the present invention is achieved as follows:

[0009] A method for improving the bending accuracy of leg pipes, comprising the following steps:

[0010] S1: Adjust the positioning plates on both sides of the pipe bender to the maximum spacing discharging state; and make the center positions of the two positioning plates coincide with the center position of the bending arm device;

[0011] S2: Place one or more steel pipes to be bent on the support platform between two positioning plates; make sure there is a gap between the positioning plates on either side and the ends of the steel pipes;

[0012] S3: Control the positioning clappers on both sides to move synchronously toward each other to hit the steel pipe; if one steel pipe is placed, the positioning clappers move to the positioning state to clamp the steel pipe; if two or more steel pipes are placed, these steel pipes are divided into the longest length steel pipe and the shorter length steel pipes whose sizes are smaller than the longest length steel pipe, and the positioning clappers on both sides move together to clamp the longest length steel pipe; at the same time, if the center position of the shorter length steel pipe coincides with the center position of the two positioning clappers when it is placed, the positioning clappers will not act on the shorter length steel pipe; if the center position of the shorter length steel pipe is offset from the center position of the two positioning clappers when it is placed, the shorter length steel pipe that is not clamped will be offset between the two positioning clappers by the hitting action of the positioning clappers on either side, and finally, when it stops moving, the center position of the shorter length steel pipe itself coincides with the center position between the two positioning clappers, or the center position of the shorter length steel pipe itself offsets and approaches the center position between the two positioning clappers;

[0013] S4: The bending arm device located at the center of the two positioning plates performs bending operations on one or more steel pipes.

[0014] Preferably, the arm bending device includes two arm bending machines spaced apart from each other. In step S1, the center position between the two arm bending machines is aligned with the center position between the two positioning plates. Since the steel pipe is bent into a U-shaped structure, two arm bending machines are required. The center position between the two arm bending machines is aligned with the center position between the two positioning plates, so that positioning is based on the center of the arm bending device. This ensures that the positioning error is not concentrated on one side of the steel pipe, but is dispersed on both sides of the steel pipe, thereby reducing the error and improving the accuracy.

[0015] Preferably, in step S3, after the two positioning clasps move closer together and contact the end of the longest steel pipe, the positioning clasps on each side will simultaneously deflect relative to the vertical plane. This allows the positioning clasps to further deflect so that the inwardly deflected portion can further contact the shorter steel pipe; thereby maximizing the effect on the shorter steel pipe, causing the center of the shorter steel pipe to shift closer to the center position between the two positioning clasps as much as possible; and the final inwardly deflected portion of the positioning clasps may also just further clamp the shorter steel pipe, similarly causing the center of the shorter steel pipe to coincide with the center position between the two positioning clasps.

[0016] Preferably, in steps S1 and S3, the two positioning clappers are controlled to move horizontally in a mirror-like manner by a driving and adjusting assembly on the pipe bending machine; the pipe bending machine includes a base, and the positioning clappers are located on both sides in front of the base; the driving and adjusting assembly is a left-right symmetrical structure and is mounted on the base; the driving and adjusting assembly includes a lifting control mechanism, on both sides of which a sliding push mechanism and a rotating and telescopic mechanism are respectively provided; the lifting control mechanism has a lifting push block; the sliding push mechanism includes a slider that can slide left and right, a driving connecting rod connected between the slider and the lifting push block, and a horizontal push rod arranged on the slider; the rotating and telescopic mechanism is arranged between the positioning clapper and the push rod; the rotating and telescopic mechanism includes a rotating connecting rod arranged in the front and rear directions, a longitudinal push plate connected to the rotating connecting rod and abutting with the push rod, and a guide rod assembly arranged between the positioning clapper and the rotating connecting rod; controlling the lifting and lowering movement of the lifting push block will act on the driving connecting rod to drive the slider to slide and make the push rod move horizontally; the push rod will push the push plate to move to act on the rotating connecting rod to rotate, and the rotating connecting rod rotates and acts on the guide rod assembly to realize the slapping action of the positioning clapper.

[0017] Preferably, the rotating telescopic mechanism further includes a support assembly connected to the base, and the rotating connecting rod rotates in conjunction with the support assembly; the push plate is arranged vertically sideways, the lower end of the push plate is fixedly connected to the rear end of the rotating connecting rod, the upper end of the push plate pushes and cooperates with the push rod; and the front end of the rotating connecting rod pushes and cooperates with the guide rod assembly; the rotation of the rotating connecting rod can push the guide rod assembly to move left and right to drive the positioning clapper. This allows the rotating connecting rod to stably rotate relative to the base, and when the push rod pushes the push plate to move, it can cause the rotating connecting rod to rotate, thereby causing the rotating connecting rod to act on the guide rod assembly to drive the positioning clapper to move.

[0018] Preferably, a fixed guide seat is connected and fixed to the front end of the support assembly; the guide rod assembly includes a longitudinal press-fit seat and at least two horizontal guide rods spaced vertically apart connected to the press-fit seat; the press-fit seat abuts against the front end of the rotating connecting rod; the guide rods slide horizontally through the fixed guide seat, and the protruding ends of the guide rods are fixedly connected to the positioning clapper. Thus, the guide rods can support the positioning clapper; the guide rods can drive the positioning clapper to move laterally by moving left and right along the fixed guide seat.

[0019] Preferably, the fixed guide seat is provided with a through-hole extending therethrough, and the guide rod is disposed in the through-hole, with the guide rod and the through-hole being loosely fitted. In step S3, the guide rod deflects in the through-hole to cause the positioning clapper to deflect. The guide rod is able to deflect in the through-hole, thereby causing the positioning clapper to twist. The positioning clapper twists in place, thereby approaching or clamping the shorter steel pipe, thereby maintaining the positioning clapper as close to the center as possible.

[0020] Preferably, the front end of the rotating connecting rod is provided with a pressing protrusion protruding toward the pressing fitting seat, and the pressing protrusion abuts and cooperates with the pressing fitting seat. Therefore, when the rotating connecting rod rotates, it can push the pressing fitting seat to move horizontally, thereby driving the positioning clapper to move horizontally.

[0021] Preferably, a return spring sleeved on the guide rod is provided between the extrusion fitting seat and the fixed guide seat, so that after the lifting control mechanism is reset, the return spring can act on the extrusion fitting seat to reset the positioning clapper.

[0022] Preferably, the support assembly includes a connecting side plate fixedly connected to the side wall of the base and an L-shaped plate horizontally connected to the connecting side plate; the L-shaped plate includes an elongated plate extending in the front-to-back direction, and a rotating support seat is provided on the elongated plate; the rotating support seat has a notch, into which the rotating connecting rod is inserted, and the rotating support seat is provided with a rotating shaft extending longitudinally through the notch, and the rotating shaft is rotated up and down through the rotating connecting rod. This allows the rotating connecting rod to swing left and right about the rotating shaft, i.e., the rotating motion of the rotating connecting rod is stable.

[0023] Preferably, a lifting control mechanism is disposed at a middle position on the upper end of the base, comprising a mounting plate fixed to the base, a cylinder disposed at the lower end of the mounting plate, and a retractable cylinder column; the cylinder column moves upward through the mounting plate, and a lifting block is connected to the upper end of the cylinder column; in steps S1 and S3, the cylinder column is controlled by the cylinder to drive the lifting block to move upward and downward to control the movement of the positioning clapper. Using a cylinder to control the lifting block provides more stable drive.

[0024] Preferably, the driving connecting rod is obliquely connected between the lifting push block and the slider; and the two ends of the driving connecting rod are respectively hinged to the slider and the lifting push block; in step S3, the cylinder controls the cylinder column to sink and drive the slider to slide outward to make the push rod move horizontally and push the push plate.

[0025] Preferably, the mounting plate is further provided with wheel mounts, one on each side of the cylinder column, each with a roller capable of rolling in place. The cylinder column is clamped between the two rollers, and the lifting and lowering movement of the cylinder column causes the rollers on both sides to roll synchronously. The provision of the wheel mounts allows the cylinder column to be raised and lowered stably in the longitudinal direction without deviation or shaking, thereby ensuring the synchronous movement of the positioning clappers on both sides.

[0026] Preferably, a slide rail is provided on the base along the left-right direction, and the slider is slidably arranged on the slide rail; the push rod is horizontally connected to the slider and extends toward the outside of the base, so that the slider moves smoothly.

[0027] Preferably, a resilient push head is provided at the end of the push rod. This allows the push rod and the push plate to be flexibly connected, rather than fixed. This design is due to the length tolerances between the steel pipes. For some longer steel pipes, when the lifting and lowering push blocks move longitudinally the same distance to control the positioning clapper to strike and position, the elastic push head allows the positioning clapper to adaptively move left and right within a certain range due to the longer steel pipes. This prevents excessive squeezing between the positioning clapper and the steel pipe, which could damage the steel pipe or the device. The structural design is ingenious and thoughtful.

[0028] Preferably, in steps S2 and S4, the support platform is provided with at least two grooves spaced apart from each other, each groove extending horizontally; the steel pipe is embedded in the groove; the shorter steel pipe will slide horizontally along the groove when struck. The steel pipe is embedded in the groove, so that after being struck, it will only move horizontally and smoothly.

[0029] The design starting point, concept and beneficial effects of the present invention using the above technical solution are:

[0030] The present invention improves leg tube bending accuracy by providing two symmetrical positioning clappers. Driven by an adjustment assembly, these clappers are stably controlled to undergo horizontal, mirror-image movement. The center positions of the clappers are set to coincide with the center of the bending arm assembly. This allows positioning to be performed based on the center positions of the two clappers. If a single steel pipe is being bent, the clappers can be brought together to clamp the pipe, aligning the pipe's center with the center of the bending arm assembly.

[0031] If more than two steel pipes are placed, the positioning clappers can clamp the steel pipe with the longest length so that the center position of the steel pipe with the longest length coincides with the center position of the two positioning clappers; at the same time, the positioning clappers can also clap the steel pipe with shorter length so that the center position of the shorter steel pipe itself is close to or coincides with the center position between the two positioning clappers; then after positioning, the center of the steel pipe is as close as possible to the center of the bending arm device; when the bending arm device bends the steel pipe, the length error of the steel pipe itself will be dispersed at both ends of the steel pipe, and the length deviation between the two legs of the U-shaped steel pipe formed by the bending is very small, which will fall within the allowable range to the greatest extent. The allowable error range is as follows: for a steel pipe with a standard length of 130 mm, the lengths of the two legs of the ideal U-shaped leg after bending are both 50 mm; however, due to the length error during cutting of the steel pipe, the actual length of the steel pipe is 134 mm. Then, the lengths of the two legs of the U-shaped leg after bending using the method of the present invention are 52 mm and 52 mm respectively, which are only 2 mm different from the length of the standard leg of 50 mm and fall within the allowable error range. In this way, the length error of the steel pipe during cutting can be reduced during the bending process, so that the U-shaped leg is always kept within the allowable error range, thereby improving the accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the three-dimensional structure of the pipe bender in an embodiment of the present invention;

[0033] Figure 2 Schematic diagram of the three-dimensional structure of one side of the pipe bending machine in an embodiment of the present invention;

[0034] Figure 3 Schematic diagram of the three-dimensional structure of one side of the pipe bender when the lifting push block sinks in the embodiment of the present invention;

[0035] Figure 4 Schematic diagram of the three-dimensional structure of the rotating and telescopic mechanism in an embodiment of the present invention;

[0036] Figure 5 Schematic diagram of the connection structure of the rotating and telescopic mechanism in an embodiment of the present invention;

[0037] Figure 6 Schematic diagram of the three-dimensional structure of the pipe bender with the positioning plate in the discharge state in an embodiment of the present invention;

[0038] Figure 7 This is a schematic diagram of the three-dimensional structure in which the steel pipe is initially placed between the positioning plates in an embodiment of the present invention;

[0039] Figure 8 A front view of a steel pipe positioning clapper for positioning a steel plate in an embodiment of the present invention;

[0040] Figure 9Schematic diagram of the three-dimensional structure of the steel pipe positioning clapper for positioning the steel plate in an embodiment of the present invention;

[0041] Figure 10 A top view of a steel pipe positioning clapper positioning a steel plate in an embodiment of the present invention;

[0042] Figure 11 Schematic diagram of the three-dimensional structure of the bending arm device bending the steel pipe in the embodiment of the present invention;

[0043] Figure 12 This is a diagram showing the principle effect of the existing technology for positioning the steel pipe in the embodiment of the present invention;

[0044] Figure 13 This is a diagram showing the principle effect of the bilateral positioning of the steel pipe in the embodiment of the present invention.

[0045] The figures are marked as follows: positioning clapper 1; base 2; lifting control mechanism 3; sliding pushing mechanism 4; rotating telescopic mechanism 5; mounting plate 6; cylinder 7; cylinder column 7a; lifting push block 8; wheel frame 9; roller 10; slider 11; driving rod 12; push rod 13; elastic push head 13a; slide rail 14; push plate 15; rotating connecting rod 16; supporting assembly 17; guide rod assembly 18; connecting side plate 19; L-shaped plate 20; long plate 21; rotating support seat 22; notch 23; rotating shaft 24; fixed guide seat 25; through hole 25a; guide rod 26; extrusion fitting seat 27; extrusion protrusion 28; return spring 29; bending arm device A; support platform 30; bending arm machine 31; groove 32; maximum length steel pipe a1; shorter length steel pipe a2. DETAILED DESCRIPTION

[0046] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0047] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0048] In the description of the present invention, the term "at least one" refers to one or more than one, unless otherwise clearly defined. The terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0049] The specific implementation of the present invention is as follows:

[0050] like Figure 1-13As shown, the present invention provides a method for improving the bending accuracy of leg pipes. The method utilizes a pipe bender with movable positioning claspers 1 on both sides to position the steel pipe. This process can reduce the length error that occurs during cutting, thereby improving accuracy. This method differs from the prior art that positions the steel pipe using only a single fixed positioning clasp, which results in the length error of the steel pipe being concentrated on one end. Specifically, the method of the present invention includes the following steps:

[0051] Step S1: Adjust the positioning plates 1 on both sides of the pipe bender to the maximum spacing discharge state; and make the center positions of the two positioning plates 1 coincide with the center position of the bending arm device A.

[0052] Specifically: Figure 1-7 As shown, the pipe bending machine includes positioning plates 1 located on the left and right sides, a base 2, and a drive and adjustment assembly disposed on the base 2 for controlling the movement of the positioning plates 1 on both sides. The two positioning plates 1 are located on the left and right sides in front of the base 2, respectively. The drive and adjustment assembly includes a lifting control mechanism 3, on both sides of which are respectively provided with a sliding push mechanism 4 and a rotating and retracting mechanism 5. Under the control of the drive and adjustment assembly, the two positioning plates 1 have a discharge state and a positioning state. In the discharge state, the positioning plates 1 on both sides are at their maximum distance to allow for placement of steel pipes. In the positioning state, the drive and adjustment assembly causes the positioning plates 1 on both sides to simultaneously move toward each other to clamp and position the steel pipes. The pipe bending machine also includes an arm bending device A disposed at the middle position of the front end of the base 2. The arm bending device A includes two arm bending machines 31 spaced apart on the left and right sides. In step S1, the center position between the two arm bending machines 31 is made to coincide with the center position between the two positioning plates 1.

[0053] like Figure 6 、 7 As shown, since the steel pipe needs to be bent into a U-shaped leg pipe, two arm bending machines 31 need to be set up; and the center position between the two arm bending machines 31 is made to coincide with the center position between the two positioning clappers 1, so that the positioning process is based on the center position of the arm bending device A; so that after positioning, the length error of the steel pipe itself will not be concentrated on one side of the steel pipe, but will be dispersed on both sides of the steel pipe, which can reduce the error and improve the accuracy.

[0054] Step S2: Figure 6 、 7 As shown, one or more steel pipes to be bent are placed on a support platform between two positioning clappers 1; and a gap is left between the positioning clappers 1 on either side and the ends of the steel pipes.

[0055] like Figure 1As shown, the bending arm device A includes a horizontal support platform 30 located between two positioning plates 1. The support platform 30 is provided with at least two grooves 32 spaced apart from each other, each extending horizontally. The grooves 32 are semicircular arc-shaped. When placing a steel pipe, it is directly embedded in the grooves 32, ensuring that the steel pipe is stably embedded in the grooves 32 without shifting. Multiple steel pipes can be placed simultaneously, allowing them to be bent simultaneously, improving processing efficiency.

[0056] Step S3: Figure 8-10 As shown, the positioning clappers 1 on both sides are controlled to move synchronously toward each other to hit the steel pipe; if only one steel pipe is placed, the positioning clappers 1 on both sides will move to the positioning state to clamp the steel pipe. If two or more steel pipes are placed, these steel pipes are divided into a maximum-length steel pipe a1 and a shorter-length steel pipe a2 that is smaller than the maximum-length steel pipe. First, the positioning claspers 1 on both sides move together to clamp the maximum-length steel pipe a1. At the same time, if the center of the shorter-length steel pipe a2 coincides with the centers of the two positioning claspers 1 when it is placed, the positioning claspers 1 will not act on the shorter-length steel pipe. If the center of the shorter-length steel pipe a2 is offset from the centers of the two positioning claspers when it is placed, the shorter-length steel pipe a2 that is not clamped will be affected by the impact of the positioning claspers on either side and move between the two positioning claspers. Finally, when the movement stops, the center of the shorter-length steel pipe a2 coincides with the center between the two positioning claspers 1, or the center of the shorter-length steel pipe a2 shifts toward the center between the two positioning claspers 1. This allows the positioning claspers 1 to simultaneously position the maximum-length steel pipe a1 and the shorter-length steel pipe a2.

[0057] like Figure 1-10 As shown, the specific structure of the pipe bender is as follows: The lifting control mechanism 3 is located in the middle of the upper end of the base 2. This lifting control mechanism 3 includes a mounting plate 6 at the bottom and a cylinder 7 at the bottom end of the mounting plate 6. A retractable cylinder column 7a on the cylinder 7 moves upward through the mounting plate 6, and a lifting push block 8 is installed at the upper end of the cylinder column 7a. A gap is provided in the middle of the base 2 to accommodate the cylinder 7. The cylinder 7a is then raised and lowered by the cylinder 7a, thereby controlling the vertical movement of the lifting push block 8. Furthermore, the mounting plate 6 is provided with a wheel mount 9 located on either side of the cylinder column 7a. Each wheel mount 9 is equipped with a rolling roller 10. The cylinder column 7a is clamped between the two rollers 10. The lifting movement of the cylinder column 7a causes the rollers 10 on both sides to roll synchronously. The wheel mount 9 ensures that the cylinder column 7a remains stable in the longitudinal direction without any deviation or sway, thereby ensuring the synchronous movement of the positioning clappers 1 on both sides.

[0058] like Figure 1-3As shown, the sliding push mechanism 4 includes a slider 11 that can slide left and right, a driving connecting rod 12 arranged between the slider 11 and the lifting push block 8, and a horizontal push rod 13 arranged on the slider 11. Specifically, the sliding push mechanism 4 is mirrored on both sides of the lifting control mechanism 3. A slide rail 14 arranged in the left and right direction is provided at the upper end of the base 2, and the slider 11 is slidably arranged on the slide rail 14. The driving connecting rod 12 is obliquely connected between the slider 11 and the lifting push block 8, and the two ends of the driving connecting rod 12 are respectively hinged to the slider 11 and the lifting push block 8, so that when the lifting push block 8 moves up and down, it can simultaneously drive the slider 11 to slide horizontally left and right along the slide rail 14. The driving connecting rod 12 is configured as two connecting rods spaced apart from each other, thereby making the linkage structure between the slider 11 and the lifting push block 8 more stable. The push rod 13 is arranged on the slider 11 and extends toward the outside of the base 2. The horizontal sliding of the slider 11 can drive the push rod 13 to move left and right.

[0059] like Figure 1-5 As shown, the rotating and retractable mechanism 5 is disposed between the positioning clapper 1 and the push rod 13. The rotating and retractable mechanism 5 includes a support assembly 17 connected to the base 2, a rotating connecting rod 16 disposed in the front-to-back direction and rotatably engaged with the support assembly 17, a longitudinal push plate 15 connected to the rotating connecting rod 16 and abutting against the push rod 13, and a guide rod assembly 18 disposed between the positioning clapper 1 and the rotating connecting rod 16. Specifically, the supporting assembly 17 includes a connecting side plate 19 connected and fixed to the side wall of the base 2, and an L-shaped plate 20 horizontally connected to the connecting side plate 19. The L-shaped plate 20 includes an elongated plate 21 disposed in the front-to-back direction, on which a rotating support seat 22 is provided. The rotating support seat 22 is provided with a notch 23 for the rotating link 16 to fit within. The rotating link 16 fits within the notch 23. A rotating shaft 24 is also provided on the rotating support seat 22, extending longitudinally through the notch 23. The rotating shaft 24 extends vertically through the rotating link 16, allowing the rotating link 16 to swing left and right about the rotating shaft 24. The push plate 15 is disposed longitudinally and sideways, with its bottom end fixedly connected to the rear end of the rotating link 16. The top end of the push plate 15 abuts against the push rod 13. When the push rod 13 moves outward, it pushes the push plate 15 outward, thereby rotating the rotating link 16. The push rod 13 is provided with an elastic push head 13a at its end, which is resilient and expandable. This ensures that the push rod 13 and the push plate 15 are not fixedly connected, but rather are flexibly connected.

[0060] Furthermore, the front end of the long board 21 is positioned in front of the base 2, and the bottom end of the front end of the long board 21 is connected to a fixed guide seat 25. The guide rod assembly 18 includes a longitudinal extrusion seat 27 and at least two horizontal guide rods 26 connected to the extrusion seat 27 and spaced apart from each other. The guide rods 26 slide horizontally through the fixed guide seat 25, and the protruding ends of the guide rods 26 are fixedly connected to the positioning clapper 1, thereby supporting the positioning clapper 1. The front end of the rotating link 16 is provided with an extrusion protrusion 28 protruding toward the extrusion seat 27, and the extrusion protrusion 28 abuts against the extrusion seat 27. Therefore, when the rotating link 16 rotates, it can push the extrusion seat 27 to move horizontally, thereby driving the positioning clapper 1 to move horizontally. Therefore, the cylinder 7 controls the sinking of the lifting push block 8 to drive the slider 11 to slide outward; thereby driving the push rod 13 to push the push plate 15 to move outward; and then drives the rotating connecting rod 16 to rotate, and the front end of the rotating connecting rod 16 can further push the extrusion fitting seat 27 to move inward, thereby causing the positioning clapper 1 to move toward the center direction of the base 2; causing the positioning clapper 1 to perform a positioning action.

[0061] Furthermore, a return spring 29, sleeved on the guide rod 26, is provided between the extrusion-fit seat 27 and the fixed guide seat 25. After the lifting control mechanism is reset, the return spring 29 acts on the extrusion-fit seat 27, causing the positioning clapper 1 to reset and move. Furthermore, the return spring 29 and the elastic push head 13a act to ensure that the transmission between the mechanisms is not rigidly connected. This design is due to the fact that there are length errors between the steel pipes. For some steel pipes with longer lengths, when the lifting push block 8 moves longitudinally the same distance to control the two-sided positioning support 1 to approach each other for positioning, due to the longer steel pipes, the return spring 29 and the elastic push head 13a enable the positioning clapper 1 to adaptively move left and right within a certain range, thereby preventing excessive compression between the positioning clapper 1 and the steel pipe, which could damage the steel pipe or the device. The structural design is ingenious and thoughtful.

[0062] Then, in step S3, the cylinder 7 is controlled to drive the cylinder column 7a downward, thereby controlling the two positioning clappers 1 to move toward each other. If only one steel pipe is placed, the two positioning clappers 1 will clamp it. Because the drive and adjustment assembly is a bilaterally symmetrical structure, the movement between the two positioning clappers 1 occurs in a mirrored manner, so that during the movement of the positioning clappers 1, the center of the bending arm device A always coincides with the center of the two positioning clappers 1. After the positioning clappers 1 clamp the single steel pipe, the center of the steel pipe will coincide with the center of the bending arm device A. This ensures that when the steel pipe is subsequently bent, the bend occurs at its center, making the two legs of the U-shaped leg tube the same length.

[0063] The key point is: Figure 6-10 As shown, if more than two steel pipes are placed, since the longest steel pipe a1 is longer than the shorter steel pipe a2, the closing movement of the positioning clappers 1 on both sides will directly clamp the longest steel pipe a1, causing the center of the longest steel pipe a1 to coincide with the center of the bending arm device A. At the same time, if the center of the shorter steel pipe a2 is offset from the center of the bending arm device A during initial placement, the end of the shorter steel pipe a2 closest to the positioning clapper 1 will also be impacted by the positioning clapper 1 on that side, causing it to shift along the groove 32 between the two positioning clappers 1. When the shorter steel pipe a2 finally stops moving, its center will coincide with the center between the two positioning clappers 1, or it will shift toward the center between the two positioning clappers 1, allowing the positioning clapper 1 to similarly act on the shorter steel pipe a2, bringing its center as close as possible to the center of the two positioning clappers 1. Of course, if, during initial placement, the center of the shorter steel tube a2 coincides with the center of the bending arm assembly A, then the shorter steel tube a2 does not need to be positioned, and the positioning clapper 1 will not affect the shorter steel tube a2. Therefore, the ultimate goal of step S3 is to ensure that the center of the steel tube coincides with the center of the bending arm assembly A as closely as possible.

[0064] like Figure 5 、 10 As shown, the fixed guide seat 25 is provided with a through hole 25a extending left and right, and the guide rod 26 is passed through the through hole 25a, and the guide rod 26 and the through hole 25a are clearance-fitted, so that the guide rod 26 can deflect to a certain extent in the through hole 25a. Figure 10 As shown, in step S3, when the two positioning clappers 1 move closer and contact the end of the maximum length steel pipe a1, the maximum length steel pipe a1 will be squeezed by the positioning clappers 1, causing the positioning clappers 1 on each side to deflect relative to the vertical plane. This allows the positioning clappers 1 to further deflect so that the inwardly deflected portion can further act on the shorter length steel pipe a2, thereby hitting the shorter length steel pipe a2. The final inwardly deflected portion of the positioning clappers 1 may also further clamp the shorter length steel pipe a2, similarly causing the center of the shorter length steel pipe a2 to coincide with the center between the two positioning clappers 1. Alternatively, even if clamping is not possible, the center of the shorter length steel pipe a2 can be made as close as possible to the center between the two positioning clappers 1.

[0065] Step S4: Figure 11As shown, the bending arm A, located between the two positioning clappers 1, performs the bending operation on the steel pipe. The bending arm 31 rotates to bend one or more steel pipes simultaneously. After bending is completed, the bending arm 31 is controlled to rotate and reset, and the cylinder column 7a is controlled to rise and reset. The positioning clappers 1 are moved and reset by the return spring 29. The bent U-shaped leg can then be removed.

[0066] In summary, the existing pipe bending method of the pipe bending machine is as follows Figure 12 As shown, the push block moves toward a fixed retaining plate to push the steel pipe, clamping it between the push block and the retaining plate. Furthermore, the bending process is based on the retaining plate's end face, meaning the distance d1 between the center of the bending arm and the retaining plate's end face is initially fixed. This results in the pipe's inherent length errors being concentrated at one end, resulting in one leg of the U-shaped leg being longer than the other. This makes it difficult to control the error within the permitted range, and the quality of the bent pipe depends entirely on the length error during cutting. For example, for a standard 130mm steel pipe, the ideal length of each end of the U-shaped leg after bending is 50mm. The permitted length difference, or tolerance, is set at 2mm. However, due to length errors during cutting, the actual length of the pipe is 134mm. Using conventional bending techniques, the two ends of the U-shaped leg are 50mm and 54mm, respectively. The pipe's inherent length errors are concentrated at one end. Alternatively, if the actual length of the steel pipe is 133 mm, the lengths of the two legs of the same U-shaped leg bent using the existing technology are 50 mm and 53 mm respectively, both exceeding the allowable error.

[0067] The pipe bending method of the present invention is as follows Figure 13As shown, the center of the bending arm device A is set to coincide with the centers of the two positioning clappers 1, and when positioning the steel pipe, the center between the two positioning clappers 1 is always used as the reference. In addition, during the positioning process, the positioning clappers 1 on both sides move synchronously to position the steel pipe, so that whether it is the longest steel pipe a1 or the shorter steel pipe a2, after positioning, the center of the steel pipe will coincide with the center position of the bending arm device or move closer to the center position of the bending arm device; thereby distributing the length error of the steel pipe itself to both sides of the steel pipe; even if the steel pipe has a large length error due to cutting, the length of the two legs of the U-shaped leg formed by bending can be kept equal or very close, so that 134mm The lengths of the two legs of the U-shaped leg will always be controlled within the allowable error range; the lengths of the two sections of the U-shaped leg after bending using the method of the present invention are 52 mm and 52 mm respectively; and the lengths of the two sections of the other 133 mm U-shaped leg are 51.5 mm and 51.5 mm respectively, which are only 2 mm and 1.5 mm different from the standard pipe length of 50 mm, and are within the allowable error range; in this way, the overall length error of the steel pipe itself is dispersed to both sides of the steel pipe, so that during the bending process, the length error of the steel pipe during the cutting process can be reduced; thereby improving the accuracy of the U-shaped leg after bending.

Claims

1. A method for improving the bending accuracy of leg pipes, characterized in that: The steps are: S1: Adjust the positioning plates on both sides of the pipe bender to the maximum spacing discharging state; and make the center positions of the two positioning plates coincide with the center position of the bending arm device; S2: Place one or more steel pipes to be bent on the support platform between two positioning plates; make sure there is a gap between the positioning plates on either side and the ends of the steel pipes; S3: Control the positioning clappers on both sides to move synchronously toward each other to clap the steel pipe; if one steel pipe is placed, the positioning clapper moves to the positioning state to clamp the steel pipe; if two or more steel pipes are placed, these steel pipes are divided into the maximum length steel pipe and the shorter length steel pipes whose sizes are smaller than the maximum length steel pipe, and the positioning clappers on both sides move closer to clamp the maximum length steel pipe; at the same time, if the center position of the shorter length steel pipe coincides with the center position of the two positioning clappers when it is placed, the positioning clapper will not act on the shorter length steel pipe; if the shorter length steel pipe When the steel pipe is placed, its center position is offset from the center position of the two positioning clappers. Then, the shorter length steel pipe that is not clamped will be offset between the two positioning clappers due to the slapping effect of the positioning clappers on either side. Finally, when it stops moving, the center position of the shorter length steel pipe itself coincides with the center position between the two positioning clappers, or the center position of the shorter length steel pipe itself shifts toward the center position between the two positioning clappers. After the two positioning clappers move closer and contact the end of the longest steel pipe, the positioning clappers on each side will simultaneously deflect relative to the vertical plane. S4: The bending arm device located at the center of the two positioning plates performs bending operations on one or more steel pipes.

2. The method for improving the bending accuracy of leg tubes according to claim 1, characterized in that: The arm bending device includes two arm bending machines spaced apart from each other. In step S1, the center position between the two arm bending machines is made to coincide with the center position between the two positioning clappers.

3. The method for improving leg tube bending accuracy according to claim 1, characterized in that: In steps S1 and S3, the two positioning clappers are controlled to move horizontally in a mirror-like manner by the driving and adjusting assembly on the pipe bending machine; the pipe bending machine includes a base, and the positioning clappers are located on both sides of the front of the base; the driving and adjusting assembly is a left-right symmetrical structure and is installed on the base; the driving and adjusting assembly includes a lifting control mechanism, and a sliding push mechanism and a rotating and telescopic mechanism are respectively provided on both sides of the lifting control mechanism; the lifting control mechanism has a lifting push block; the sliding push mechanism includes a slider that can slide left and right, a driving connecting rod connected between the slider and the lifting push block, and a horizontal push rod arranged on the slider; the rotating and telescopic mechanism is arranged between the positioning clapper and the push rod; the rotating and telescopic mechanism includes a rotating connecting rod arranged in the front and back direction, a longitudinal push plate connected to the rotating connecting rod and abutting with the push rod, and a guide rod assembly arranged between the positioning clapper and the rotating connecting rod; controlling the lifting and lowering movement of the lifting push block will act on the driving connecting rod to drive the slider to slide and make the push rod move horizontally; the push rod will push the push plate to move to act on the rotating connecting rod to rotate, and the rotating connecting rod rotates and acts on the guide rod assembly to realize the slapping action of the positioning clapper.

4. The method for improving leg tube bending accuracy according to claim 3, characterized in that: The rotating and telescopic mechanism also includes a supporting assembly connected to the base, and the rotating connecting rod rotates in cooperation with the supporting assembly; the push plate is arranged longitudinally sideways, the lower end of the push plate is fixedly connected to the rear end of the rotating connecting rod, and the upper end of the push plate pushes and cooperates with the push rod; and the front end of the rotating connecting rod pushes and cooperates with the guide rod assembly; the rotation of the rotating connecting rod can push the guide rod assembly to move left and right to drive the positioning clapper to move.

5. The method for improving leg tube bending accuracy according to claim 4, characterized in that: A fixed guide seat is connected and fixed to the front end of the support assembly; the guide rod assembly includes a longitudinal extrusion fit seat and at least two horizontal guide rods spaced up and down connected to the extrusion fit seat; the extrusion fit seat abuts and fits with the front end of the rotating connecting rod; the guide rod slides horizontally through the fixed guide seat, and the protruding end of the guide rod is fixedly connected to the positioning clapper.

6. The method for improving leg tube bending accuracy according to claim 5, characterized in that: The fixed guide seat is provided with a through hole running through the left and right sides, the guide rod is passed through the through hole, and the guide rod and the through hole are clearance-fitted; in step S3, the guide rod deflects in the through hole so that the positioning clapper will deflect relative to the vertical plane.

7. The method for improving leg tube bending accuracy according to claim 5, characterized in that: The front end of the rotating connecting rod is provided with an extrusion protrusion protruding toward the extrusion fitting seat, and the extrusion protrusion is in abutment with the extrusion fitting seat.

8. The method for improving leg tube bending accuracy according to claim 5, characterized in that: A return spring sleeved on the guide rod is provided between the extrusion fitting seat and the fixed guide seat.

9. The method for improving leg tube bending accuracy according to claim 4, characterized in that: The support assembly includes a connecting side plate connected and fixed to the side wall of the base and an L-shaped plate horizontally connected to the connecting side plate; the L-shaped plate includes a long plate arranged along the front and rear directions, and a rotating support seat is provided on the long plate; a notch is provided on the rotating support seat, and the rotating connecting rod is embedded in the notch, and a rotating shaft is provided on the rotating support seat and longitudinally passes through the notch, and the rotating shaft rotates up and down and passes through the rotating connecting rod.

10. The method for improving leg pipe bending accuracy according to claim 3, characterized in that: The lifting control mechanism is arranged at the middle position of the upper end of the base, and the lifting control mechanism includes a mounting plate fixed on the base, a cylinder arranged at the bottom end of the mounting plate, and a retractable cylinder column; the cylinder column moves upward through the mounting plate, and the lifting push block is connected to the upper end of the cylinder column; in steps S1 and S3, the cylinder column is controlled by the cylinder to drive the lifting push block to move up and down to control the movement of the positioning clapper.

11. The method for improving leg pipe bending accuracy according to claim 10, characterized in that: The driving connecting rod is obliquely connected between the lifting push block and the slider; and the two ends of the driving connecting rod are respectively hinged to the slider and the lifting push block; in step S3, the cylinder controls the cylinder column to sink and drive the slider to slide outward to make the push rod move horizontally and push the push plate.

12. The method for improving leg pipe bending accuracy according to claim 10, characterized in that: The mounting plate is also provided with wheel seats located on the left and right sides of the cylinder column respectively, and each wheel seat is provided with a roller that can roll in place; the cylinder column is clamped between the two rollers; the lifting movement of the cylinder column will cause the rollers on both sides to roll synchronously.

13. The method for improving leg pipe bending accuracy according to claim 3, characterized in that: A slide rail is provided on the base along the left and right directions, and a slider is slidably arranged on the slide rail; the push rod is horizontally connected to the slider and extends toward the outer side of the base.

14. The method for improving leg pipe bending accuracy according to claim 3, characterized in that: An elastic push head which can be elastically extended and retracted is arranged at the end of the push rod.

15. The method for improving leg pipe bending accuracy according to claim 1, characterized in that: In steps S2 and S4, the support platform is provided with at least two grooves spaced apart from each other in the front and back directions, each groove extending horizontally; the steel pipe is embedded in the groove; the shorter steel pipe will slide horizontally along the groove under the action of slapping.

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