A pipe bending processing method, CNC pipe bending machine and control method thereof

Abstract

The present invention relates to a pipe bending method, a CNC pipe bending machine and a control method thereof, and belongs to the technical field of pipe processing. The CNC pipe bending machine includes a feeding trolley, which includes a slide, a feeding spindle device and a post-loading mandrel device. The feeding spindle device includes a feeding spindle and a clamping claw mechanism. The clamping claw mechanism is a two-claw structure, including left and right clamping claws, and there is a set space with an upper opening between the left and right clamping claw seats. The post-loading mandrel device includes a supporting crossbeam, a lifting drive and a post-loading mandrel mechanism fixed on the lifting mover of the lifting drive. The post-loading mandrel mechanism includes a mandrel seat, a post-loading mandrel movably mounted on the mandrel seat along the feeding direction, and an elastic reset mechanism coupled between the two aforementioned two. The elastic restoring force of the reset mechanism is used to force the post-loading mandrel to move forward. Based on the post-loading mandrel mechanism, the quality of pipe bending processing for pipe fittings with both ends processed can be improved, and the pipe can be widely used in manufacturing fields such as refrigeration and automobiles.

Description

Technical Field

[0001] The present invention relates to the technical field of pipe processing, in particular to a numerical control pipe bending machine and a control method and a pipe bending processing method suitable for use with the numerical control pipe bending machine. Background Art

[0002] During the manufacturing process of tubular components, it is often necessary to bend the pipes. For example, in the production of tubular components used in automobiles and aircraft, various pipe bending machines with different structures are used to bend the pipes. This type of pipe bending machine structurally comprises a frame, a control unit, a feed trolley mounted on the frame and controlled by the control unit, a guide die unit, and a machine head. The machine head is equipped with a circular die for controlling the bending radius, a swing arm, and a clamping die mounted on the swing arm for clamping the pipe together with the circular die. Depending on the bending direction, pipe bending machines are divided into left-bending pipe bending machines, right-bending pipe bending machines, and left-right bending pipe bending machines. Left-right bending pipe bending machines are often used for bending complex pipelines. For example, patent application publication number CN101817038A discloses a bending mechanism for constructing a left-right bending CNC pipe bending machine.

[0003] Furthermore, patent publication CN107282720A discloses a CNC tube bender for left and right bending. The machine comprises a frame, a control unit, a tube bending device mounted on the frame and controlled by the control unit, and a feed carriage. The tube bending device comprises a die head, a die guide unit, and a die change unit. The die head comprises a mounting base, and left and right tube bending units mounted on the mounting base and driven by a common tube bending motor. The tube bending units comprise a circular die, a swing arm, and a clamping die mounted on the swing arm. The die change unit, under the control of the control unit, drives the die head in a lateral and vertical direction relative to the frame, perpendicular to the axis of the tube to be bent, switching the CNC tube bender between left and right bending modes. The left and right tube bending units are driven by a common tube bending motor, and the die change unit enables switching between the left and right bending modes. This not only effectively improves tube bending quality but also enhances the compactness of the overall layout, making it widely applicable in fields such as air conditioning and aviation.

[0004] Although the use of a left-right co-bending CNC pipe bender can solve the problems of one-way pipe bending, it still has the same problems as the one-way pipe bender. For example, when bending pipe fittings with end treatments on both ends, the pipe end size will deviate during the last bend, thereby reducing the bending quality of the pipe fitting. Summary of the Invention

[0005] The main purpose of the present invention is to provide a numerically controlled pipe bender with an improved structure, so as to better bend pipe fittings with both ends treated.

[0006] Another object of the present invention is to provide a control method and a pipe bending method suitable for use with the above-mentioned CNC pipe bending machine.

[0007] In order to achieve the above-mentioned main purpose, the present invention provides a CNC pipe bending machine including a control unit, a frame, a pipe bending device and a feeding trolley installed on the frame and controlled by the control unit, the pipe bending device including a machine head and a guide die unit, the machine head including a circular die, a clamping die and a clamping die driver for driving the two to open and close; the feeding trolley includes a slide movably mounted on the frame, a feeding spindle device installed on the slide, and a feeding driver for driving the slide to slide back and forth along the feeding direction; the feeding spindle device includes a feeding spindle, a clamping claw mechanism fixedly mounted on the front end of the feeding spindle through a clamping claw mounting seat, and a clamping driver for driving the clamping claw mechanism to clamp or release the workpiece; the clamping claw mechanism is a two-claw structure, including a left clamping claw seat, a right clamping claw seat, a left clamping claw fixed on the front end of the left clamping claw seat, and a right clamping claw fixed on the front end of the right clamping claw seat, and there is a clamping claw seat between the left clamping claw seat and the right clamping claw seat. The camming member is a pair of camming members with a pair of camming teeth, each of which is connected to the other end of the camming member by a toothed connection, and the camming member is connected to the tube clamping mold cavity between the two clamping claws; a post-loading mandrel device is installed on the slide, including a support beam extending to the upper side of the clamping claw mechanism, a lifting drive fixedly installed on the front end of the support beam, and a post-loading mandrel mechanism fixedly installed on the lifting mover of the lifting drive; the post-loading mandrel mechanism includes a mandrel seat, a post-loading mandrel movably mounted on the mandrel seat along the feeding direction, and an elastic reset mechanism coupled between the post-loading mandrel and the mandrel seat; the elastic restoring force of the elastic reset mechanism is used to force the post-loading mandrel to move forward; the lifting drive is used to drive the mandrel seat to descend and be sheathed in the sheathing space, so that the post-loading mandrel can be movably sheathed in the tube clamping mold cavity, and the clamping claw mounting seat or the mandrel seat constitutes a limit stop mechanism for the backward movement range of the post-loading mandrel; and the lifting drive is used to drive the mandrel seat to rise and be lifted away from the sheathing space.

[0008] In the above technical solution, based on the newly added post-insertion mandrel device, the controllable range of the bending size in the last bending process of the pipe fittings with both ends processed can be effectively ensured, thereby improving the bending processing quality of the product.

[0009] Specifically, the elastic reset mechanism is a compression spring mounted on the rear-mounted mandrel, with the rear end of the compression spring pressing against the mandrel seat and the front end pressing against the side shoulder of the rear-mounted mandrel. This technical solution facilitates equipment installation. The specific structure of the elastic reset mechanism can also be constructed using other elastic mechanisms, such as a pair of permanent magnets with like poles facing each other, or an elastic rubber ring.

[0010] A preferred solution is for the mandrel holder to be a T-shaped structure, comprising a vertical mounting base for fitting within the fitting space and a transverse connecting base supported horizontally on the left and right clamping claw seats. The vertical mounting base is provided with a fitting hole, into which the post-installed mandrel can be movably fitted. This technical solution utilizes the T-shaped structure to form a limiting mechanism and facilitates the layout of the detection mechanism.

[0011] A further solution is that the lifting drive is a double-rod lifting cylinder, the lower ends of the two piston rods of the double-rod lifting cylinder are fixedly connected to one end of the transverse connecting seat respectively. The use of a double-rod mechanism facilitates the installation of the equipment and can simplify the equipment structure.

[0012] A preferred solution is to removably connect the rear-loading mandrel mechanism to the lifting mover; the left gripping claw is removably attached to the front end of the left gripping claw seat; and the right gripping claw is removably attached to the front end of the right gripping claw seat. This technical solution facilitates the replacement of gripping claws and rear-loading mandrels to correspond to pipe diameters, improving the adaptability of the equipment. By replacing the left gripping claw and rear-loading mandrel mechanism to accommodate different pipe sizes, the adaptability of the entire machine can be improved.

[0013] The preferred solution is that the CNC pipe bending machine includes a pipe end supporting unit installed on the frame and arranged on the side of the machine head; the pipe end supporting unit includes a mounting bracket, a supporting clamp, a clamp advance and retreat cylinder, and a clamp cylinder for driving the supporting clamp to open and close; the cylinder body of the clamp advance and retreat cylinder is fixedly mounted on the mounting bracket, and the cylinder body of the clamp cylinder is fixedly mounted on the piston rod of the clamp advance and retreat cylinder; the clamp advance and retreat cylinder is used to drive the clamp cylinder to drive the supporting clamp to move forward to the front pipeline of the pipe fitting, or retreat to avoid the front pipeline. This technical solution can support the pipe fitting when the pipe fitting is relatively long, effectively preventing the front end of the pipe fitting from sagging and causing the center to be misaligned, and being clamped by the clamping die, or being clamped by the guide die and causing pipe loss, thereby improving the quality of pipe processing.

[0014] In order to achieve the above-mentioned purpose of the invention, the control method provided by the present invention is aimed at the CNC pipe bending machine described in any of the above-mentioned technical solutions, and the control method includes the following steps: controlling the lifting drive to keep the mandrel seat in a position suspended from the sheathing space, while avoiding the bending process, until during the last bend of the rear end of the pipe fitting, driving the mandrel seat to descend and sheath in the sheathing space, and then driving the rear-installed mandrel to extend into the rear end of the pipe fitting to bend the rear end of the pipe fitting.

[0015] The specific solution is that during the final bend of the rear end of the pipe, the control method includes the following steps:

[0016] After controlling the clamping claw mechanism to open and release the clamping of the pipe, controlling the feeding driver to drive the slide to move backward to a position where the pipe and the descending action of the rear-loading mandrel device are avoided;

[0017] Controlling the lifting drive to drive the mandrel holder to descend and be sheathed in the sheathing space, and causing the rear-installed mandrel to be sheathed in the tube clamp mold cavity;

[0018] Controlling the feeding driver to drive the slide forward until the pipe fitting is sleeved between the pipe clamp die cavity and the post-installation mandrel, and the rear end of the post-installation mandrel is pressed against the clamping claw mounting seat because the front end of the post-installation mandrel is sleeved on the pipe fitting port;

[0019] Controlling the clamping driver to drive the clamping claw mechanism to clamp the pipe fitting, then controlling the feeding mechanism to feed the material to the pipe bending position, and then controlling the clamping die driver to drive the clamping die to approach the circular die to clamp the pipe fitting;

[0020] After controlling the clamping driver to drive the clamping claw mechanism to open and release the clamping of the pipe fitting, the slide is driven to move backward, and then the guide die unit is controlled to be close to the pipe fitting, and the rear-installed mandrel is kept in the rear end of the pipe fitting to continue the bending action.

[0021] In order to achieve the above-mentioned purpose of the invention, the pipe bending method provided by the present invention is based on a CNC pipe bending machine to bend the pipe fittings whose both ends have been processed. The pipe bending method includes the following steps: in the process of bending the aforementioned pipe fitting without an inserted mandrel, to the process of performing the last bend on the rear end of the pipe fitting, a rear inserted mandrel is inserted into the rear end of the pipe fitting, and the rear end of the pipe fitting is bent based on the rear inserted mandrel.

[0022] The specific solution is that the CNC pipe bending machine is the CNC pipe bending machine described in any of the above technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a three-dimensional diagram of a CNC pipe bender in an embodiment of the present invention;

[0024] Figure 2 for Figure 1 A partial enlarged view in FIG;

[0025] Figure 3 This is a three-dimensional diagram of the feeding trolley in the embodiment of the present invention with the slide and feeding driver omitted;

[0026] Figure 4 A structural diagram of the front end portion of the feeding spindle and the rear-mounted mandrel device clamped thereon in an embodiment of the present invention;

[0027] Figure 5This is a structural diagram of a pipe end supporting unit in an embodiment of the present invention;

[0028] Figure 6 A three-dimensional diagram of a mold changing unit according to an embodiment of the present invention;

[0029] Figure 7 A three-dimensional diagram of a machine head according to an embodiment of the present invention;

[0030] Figure 8 for Figure 1 Partial enlarged view of B in FIG;

[0031] Figure 9 for Figure 7 Partial enlarged view of C in the figure;

[0032] Figure 10 It is a three-dimensional diagram of the guide mold unit in an embodiment of the present invention after omitting the guide mold. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the embodiments and the accompanying drawings.

[0034] Example

[0035] See also Figures 1 to 10 This CNC pipe bender 1 is a left-right co-bending CNC pipe bender. Structurally, the CNC pipe bender 1 includes a frame 10, a control unit, and a pipe bending device, a feed trolley 4, and a pipe end support unit 3 mounted on the frame 10. During operation, the pipe bending device, the feed trolley 4, and the pipe end support unit 3 are all controlled by the control unit. The pipe bending device includes a die head 2, a die guide unit 6, and a die change unit 5. The control unit includes a processor, a memory, and a touch panel 12. The processor receives operator input commands via the touch panel 12 and, by executing a computer program stored in the memory, controls the movement of the pipe bending device, the pipe end support unit 3, and the feed trolley 4 according to a pre-set program to perform operations such as pipe bending.

[0036] See also Figure 1 and Figures 6 to 10 The machine head 2 includes a mounting base 20, a bending motor 22 mounted on the mounting base 20, and a bending unit. The bending unit includes a multi-layer circular die 21, a driving spindle 23, a swing arm 24, and a clamping mechanism 25 mounted on the swing arm 24. The clamping mechanism 25 includes a clamping die and a clamping driver. The clamping driver is used to drive the clamping die and the circular die to open and close to clamp or release the pipe to be bent.

[0037] The drive spindle 23 is rotatably mounted on the mounting base 20 via multiple bearings to rotatably support the entire pipe bending unit on the mounting base 20. Two or more layers of circular dies are coaxially mounted on the drive spindle 23 in a stacked manner. The fixed end of the swing arm 24 is also mounted on the drive spindle 23. The drive spindle 23 drives the circular dies and the swing arm 24 to rotate around the axis of the drive spindle 23. In other words, the multiple circular dies and the swing arm 24 drive the spindle together.

[0038] See also Figure 1 、 Figure 7 、 Figure 9 and Figure 10 The guide mold unit 6 includes a guide mold base 61, a multi-layer guide mold detachably fixed on the guide mold base 61, and a two-dimensional driving mechanism.

[0039] The two-dimensional driving mechanism includes a transverse slide 62, a transverse cylinder 63 and an axial drive motor 64. The transverse slide 62 can be slid on the mounting seat 20 through a transverse guide rail slider mechanism 68, that is, the entire guide mold unit 6 is installed on the mounting seat 20. The transverse guide rail slider mechanism includes a linear guide rail arranged transversely perpendicular to the axial direction of the pipe to be bent; the cylinder body of the transverse cylinder 63 is fixedly connected to the mounting seat 20, and its cylinder rod is fixedly connected to the transverse slide 62, thereby pushing the transverse slide 62 to move back and forth laterally relative to the mounting seat 20.

[0040] The guide die base 61 is installed on the transverse slide 62 through an axial guide rail slider mechanism. The axial guide rail slider mechanism specifically includes a linear guide rail 651 arranged along the axial direction of the pipe to be bent and a slider 652 fixed on the transverse slide 62. The linear guide rail 651 is fixedly connected to the back side of the guide die base 61. The axial drive motor 64 drives the guide die base 61 to move back and forth in the longitudinal direction through the gear rack mechanism, thereby pushing the guide die base 61 to move back and forth in the transverse direction relative to the transverse slide 62.

[0041] See also Figure 6 The mold change unit 5 includes a vertical drive mechanism 50, a vertical guide rail and slider mechanism, a vertical slide 52, a transverse drive mechanism 53, a transverse guide rail and slider mechanism 54, a transverse slide 55, a transverse position detection mechanism 56, and a vertical position detection mechanism 57, forming a two-dimensional drive mechanism. The entire mold change unit 5 is mounted on the frame 10 via a mounting plate 50.

[0042] The vertical slide 52 is slidably mounted on the frame 20 via a vertical guide rail and slider mechanism. The vertical drive mechanism 50 includes a servo motor and a screw-nut mechanism, which drives the vertical slide 52 to move back and forth vertically relative to the frame 20 through the forward and reverse rotation of the servo motor. The transverse slide 55 is slidably mounted on the vertical slide 52 via a transverse guide rail and slider mechanism 54. The transverse drive mechanism includes a servo motor and a screw-nut mechanism, which drives the transverse slide 55 to move back and forth horizontally relative to the vertical slide 52 through the forward and reverse rotation of the servo motor. In other words, driven by the two drive mechanisms, the transverse slide 55 can move two-dimensionally relative to the frame 20 in a plane perpendicular to the axis of the pipe to be bent.

[0043] See also Figure 1 and Figures 6 to 10 The machine head 4 and the guide die unit 6 are mounted on the transverse slide 55 through the mounting base 20, thereby driving the entire machine head 4 and the transverse die unit 6 to move in a two-dimensional plane relative to the bent pipe.

[0044] See also Figure 1 and Figure 5 The pipe end supporting unit 3 is fixedly installed on the frame and arranged on the side of the machine head 4, and is used to support the front end of the pipe to be bent delivered by the feeding trolley 4; the pipe end supporting unit 3 specifically includes a mounting bracket 30, a supporting clamp 31, a clamp advance and retreat cylinder 32 and a clamp cylinder 33 for driving the supporting clamp 31 to open and close. The cylinder body of the jaw advance and retreat cylinder 32 is fixedly mounted on the mounting bracket 30, and the cylinder body of the jaw cylinder 33 is fixedly mounted on the piston rod of the jaw advance and retreat cylinder 32. Thus, during operation, the jaw advance and retreat cylinder 32 is used to drive the jaw cylinder 33 to drive the material support jaw 31 forward to the front pipeline of the pipe fitting, thereby supporting the pipe fitting by movably clamping it, which is mainly used in the process of feeding and bending long pipes, or retreating to avoid the front pipeline of the pipe fitting, which is mainly used in the process of feeding and bending short pipes, thereby avoiding interference with the short pipe bending process and supporting the end of the long pipe to improve the bending quality. Since the material support jaw 31 forms a gap 310 for the pipe fitting to pass through after closing, it can play a supporting role while not interfering with the forward movement of the pipe fitting.

[0045] See also Figures 1 to 4The feeding trolley 4 includes a feeding guide rail 41 fixed on the frame 10, a feeding slide 42 slidably mounted on the feeding guide rail 41 through a guide rail slider, the direction of the feeding guide rail 41 is the feeding direction in this embodiment, a feeding rack 43 fixed on the frame 10 is arranged in a direction parallel to the feeding guide rail 41, a feeding spindle 44 rotatably mounted on the feeding slide 42 around its own axis, a rotary servo motor 45 for driving the feeding spindle 44 to rotate, and a feeding servo motor 46 for driving the feeding slide 42 to reciprocate along the feeding guide rail 41 through the cooperation of the gear provided on the rotor shaft and the feeding rack 43; wherein, the feeding servo motor 46 and the gear rack mechanism together constitute the feeding driver in this embodiment.

[0046] The feeding spindle 44, the clamping drive and the clamping claw mechanism installed on the front end of the feeding spindle 44 together constitute the feeding spindle device in this embodiment, wherein the clamping drive is constructed using a cylinder, and the clamping claw mechanism is controlled by a sliding sleeve to open and release the pipe or close and clamp the pipe.

[0047] In this embodiment, the clamping claw mechanism 7 is fixedly mounted on the front end of the feeding spindle 44 through the clamping claw mounting seat 48; the clamping claw mechanism 7 is a two-claw structure, specifically including a left clamping claw seat 70, a right clamping claw seat 71, a left clamping claw 72 fixed on the front end of the left clamping claw seat 70, and a right clamping claw 73 fixed on the front end of the right clamping claw seat 71. There is a set space 74 between the left clamping claw seat 70 and the right clamping claw seat 70, which is at least open at the top, and the set space 74 is connected to the pipe clamping mold cavity 75 between the two clamping claws; in this embodiment, the left clamping claw 72 is detachably fixed on the front end of the left clamping claw seat 70, and the right clamping claw 73 is detachably fixed on the front end of the right clamping claw seat 71, so that during use, they can be replaced with a clamping mold cavity suitable for the pipe to be bent according to actual conditions.

[0048] A post-loading mandrel device 8 is installed on the slide 44, including a supporting beam 80 extending to the upper side of the clamping claw mechanism 7, a lifting drive 81 fixedly installed on the front end of the supporting beam 80, and a post-loading mandrel mechanism 9 fixedly installed on the lifting mover 810 of the lifting drive 81; the post-loading mandrel mechanism 9 includes a mandrel seat 90, a post-loading mandrel 91 movably installed on the mandrel seat 90 along the feeding direction, and an elastic reset mechanism 92 coupled between the above two; the elastic restoring force of the reset mechanism 92 is used to force the post-loading mandrel 91 to move forward; in this embodiment, the elastic reset mechanism 91 is a compression spring sleeved on the post-loading mandrel 91, the rear end of the compression spring presses against the mandrel seat 90, and the front end presses against the side boss of the post-loading mandrel 91, so that the mandrel can be reset by utilizing its tensile elastic restoring force.

[0049] In this embodiment, the mandrel holder 91 is a T-shaped structure, comprising a vertical mounting seat 910 for fitting within the fitting space 74, and a transverse connecting seat 911 extending horizontally above the left and right clamping jaw seats 70 and 71. The vertical mounting seat 910 is provided with a fitting hole 9101, into which the later-installed mandrel 91 is movably fitted. In this embodiment, the lifting actuator 81 is constructed using a double-rod lifting cylinder, the lower ends of the two piston rods of which are fixedly connected to one end of the transverse connecting seat 911. During operation, the lifting drive 81 is used to drive the mandrel seat 90 to descend and the vertical mounting seat 910 to be mounted in the mounting space 74, so that the later-installed mandrel 91 can be movably mounted in the tube clamp mold cavity 75, and the clamping claw mounting seat 48 constitutes a limit stop mechanism for the backward movement range of the later-installed mandrel 91. The mandrel seat 90 can also be used to constitute a limit stop mechanism for the backward movement of the mandrel; the lifting drive 81 is also used to drive the mandrel seat 90 to rise and lift it out of the mounting space 74.

[0050] During operation, the pipe bender 1 is controlled by the following method, which specifically includes the following steps:

[0051] The lifting drive is controlled to keep the mandrel holder 90 in a position suspended from the sleeve space 70 to avoid the pipe bending process. During the final bend of the rear end of the pipe fitting, the mandrel holder 90 is driven to descend and sleeved in the sleeve space 70, and then the rear-installed mandrel 91 is driven to extend into the rear end of the pipe fitting to perform the pipe bending process on the rear end of the pipe fitting.

[0052] In this step, during the last bend of the rear end of the pipe: (1) after the clamping claw mechanism 7 is controlled to open and release the clamping of the pipe, the feed drive is controlled to drive the slide 44 to move backward to a position where the pipe and the subsequent mandrel device 8 avoid the descending action; (2) the lifting drive is controlled to drive the mandrel seat 90 to descend and fit into the fitting space 70, and the subsequent mandrel 91 is fit into the pipe clamp mold cavity 75; (3) the feed drive is controlled to drive the slide 44 forward until the pipe is fit between the pipe clamp mold cavity 75 and the subsequent mandrel 91, and due to the The front end of the rear-loading mandrel 91 is sleeved onto the pipe fitting port so that the rear end of the rear-loading mandrel is pressed against the clamping claw mounting seat 48; (4) the clamping driver is controlled to drive the clamping claw mechanism 7 to clamp the pipe fitting, and then the feeding is controlled to feed the material to the bending position, and then the clamping die driver is controlled to drive the clamping die close to the circular die to clamp the pipe fitting; (5) the clamping driver is controlled to drive the clamping claw mechanism 7 to open and release the clamping of the pipe fitting, and then the slide 44 is driven to move backward, and then the guide die unit is controlled to be close to the pipe fitting, and the rear-loading mandrel continues to be sleeved inside the rear end of the pipe fitting to continue the bending action.

[0053] Furthermore, the pipe bending method of the present application is not necessarily based on the aforementioned pipe bending machine for pipe bending, but can also be based on other structures, utilizing a loading robot to load a post-installed mandrel. Therefore, the pipe bending method is as follows: First, the pipe is bent without a mandrel, and then, during the final bend at the rear end of the pipe, a post-installed mandrel is inserted into the rear end of the pipe, and the rear end of the pipe is bent using the post-installed mandrel.

[0054] In the patent of this invention, "above", "left", "right", "front" and "back" are relative position concepts without any restrictive description. For example, rotating the feed spindle and the rear-loading core rod device arranged above it as a whole around the rotation axis of the feed spindle will not affect its use.

Claims

1. A CNC pipe bender, comprising a control unit, a frame, and a pipe bending device and a feeding trolley mounted on the frame and controlled by the control unit, the pipe bending device comprising a die head and a guide die unit, the die head comprising a circular die, a clamping die, and a clamping die driver for driving the two to open and close; the feeding trolley comprising a slide movably mounted on the frame, a feeding spindle device mounted on the slide, and a feeding driver for driving the slide to slide back and forth in a feeding direction; the feeding spindle device comprising a feeding spindle, a clamping claw mechanism fixedly mounted on the front end of the feeding spindle via a clamping claw mounting seat, and a clamping driver for driving the clamping claw mechanism to clamp or release a workpiece; characterized in that: The clamping claw mechanism is a two-claw structure, including a left clamping claw seat, a right clamping claw seat, a left clamping claw fixed to the front end of the left clamping claw seat, and a right clamping claw fixed to the front end of the right clamping claw seat. A set space with at least an upper opening is present between the left clamping claw seat and the right clamping claw seat, and the set space is communicated with the tube clamp mold cavity between the two clamping claws. A post-loading mandrel device is mounted on the slide, comprising a support beam extending to the upper side of the clamping claw mechanism, a lifting drive fixedly mounted on the front end of the support beam, and a post-loading mandrel mechanism fixedly mounted on the lifting mover of the lifting drive; the post-loading mandrel mechanism comprises a mandrel seat, a post-loading mandrel mounted on the mandrel seat so as to be reciprocating along the feeding direction, and an elastic reset mechanism coupled between the post-loading mandrel and the mandrel seat; the elastic restoring force of the elastic reset mechanism is used to force the post-loading mandrel to move forward; The lifting drive is used to drive the mandrel seat down until the mandrel seat can be sheathed in the sheathing space, so that the later-installed mandrel can be movably sheathed in the tube clamp mold cavity, and the clamping claw mounting seat or the mandrel seat constitutes a limit stop mechanism for the rearward movement range of the later-installed mandrel; the lifting drive is used to drive the mandrel seat up and lift it out of the sheathing space; The elastic reset mechanism includes a compression spring sleeved on the rear-mounted mandrel, the rear end of the compression spring presses against the mandrel seat, and the front end presses against the side boss of the rear-mounted mandrel.

2. The CNC pipe bender according to claim 1, characterized in that: The core rod seat is a T-shaped structure, including a vertical mounting seat for being sleeved in the sleeve space, and a horizontal connecting seat horizontally supported on the upper side of the left clamping claw seat and the right clamping claw seat; a sleeve hole is provided on the vertical mounting seat, and the rear-installed core rod can be movably sleeved in the sleeve hole.

3. The CNC pipe bender according to claim 2, characterized in that: The lifting driver is a double-rod lifting cylinder, and the lower ends of the two piston rods of the double-rod lifting cylinder are correspondingly fixedly connected to one end of the transverse connecting seat.

4. The CNC pipe bender according to any one of claims 1 to 3, characterized in that: The rear-loading mandrel mechanism is detachably fixedly connected to the lifting mover; The left clamping claw is detachably fixed on the front end portion of the left clamping claw seat; the right clamping claw is detachably fixed on the front end portion of the right clamping claw seat.

5. The CNC pipe bender according to any one of claims 1 to 3, characterized in that: The CNC pipe bender includes a pipe end supporting unit mounted on the frame and arranged on the side of the machine head; The pipe end supporting unit includes a mounting bracket, a supporting jaw, a jaw advance and retreat cylinder, and a jaw cylinder for driving the supporting jaw to open and close; the cylinder body of the jaw advance and retreat cylinder is fixedly mounted on the mounting bracket, and the cylinder body of the jaw cylinder is fixedly mounted on the piston rod of the jaw advance and retreat cylinder; the jaw advance and retreat cylinder is used to drive the jaw cylinder to drive the supporting jaw to move forward to the front pipeline of the pipe fitting, or retreat to avoid the front pipeline.

6. A control method for a CNC pipe bender, wherein the CNC pipe bender is the CNC pipe bender according to any one of claims 1 to 5, characterized in that: The control method comprises the following steps: The lifting drive is controlled to keep the mandrel seat in a position suspended from the sleeve space to avoid the pipe bending process. During the process of performing the final bend on the rear end of the pipe fitting, the mandrel seat is driven to descend and sleeved in the sleeve space, and then the rear-installed mandrel is driven to extend into the rear end of the pipe fitting to perform the pipe bending process on the rear end of the pipe fitting.

7. The control method according to claim 6, characterized in that: The steps in the process of making the final bend on the rear end of the pipe include: After controlling the clamping claw mechanism to open and release the clamping of the pipe, controlling the feeding driver to drive the slide to move backward to a position where the pipe and the descending action of the rear-loading mandrel device are avoided; Controlling the lifting drive to drive the mandrel holder to descend and be sheathed in the sheathing space, and causing the rear-installed mandrel to be sheathed in the tube clamp mold cavity; Controlling the feeding drive to drive the slide forward until the pipe fitting is sleeved between the pipe clamp die cavity and the post-installation mandrel, and because the front end of the post-installation mandrel sleeves the pipe fitting port, the rear end of the post-installation mandrel presses against the clamping claw mounting seat or the mandrel seat; Control the clamping driver to drive the clamping claw mechanism to clamp the pipe fitting, then control the feeding trolley to feed the material to the pipe bending position, and then control the clamping die driver to drive the clamping die close to the circular die to clamp the pipe fitting; After controlling the clamping driver to drive the clamping claw mechanism to open and release the clamping of the pipe fitting, the slide is driven to move backward, and then the guide die unit is controlled to be close to the pipe fitting, and the rear-installed mandrel is kept in the rear end of the pipe fitting to continue the bending action.

8. A pipe bending method, which uses a CNC pipe bending machine to bend a pipe fitting with both ends processed, characterized in that: The pipe bending processing method comprises the following steps: During the process of bending the aforementioned pipe fitting without an inserting mandrel until the last bend is performed on the rear end portion of the pipe fitting, a rear inserting mandrel is inserted into the rear end portion of the pipe fitting, and the rear end portion of the pipe fitting is bent based on the rear inserting mandrel; The CNC pipe bender is the CNC pipe bender according to any one of claims 1 to 5.

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