Self-lubricating structure and self-lubricating method of mandrel of numerical control pipe bender

Abstract

This invention relates to the field of CNC pipe bending machine technology, specifically to a self-lubricating structure and method for a CNC pipe bending machine mandrel. The self-lubricating structure includes a mandrel, an oil inlet hole arranged axially on the mandrel, and an oil outlet hole located at the front end of the mandrel and communicating with the oil inlet hole. The oil outlet hole is arranged laterally relative to the oil inlet hole, and a one-way valve is installed within the oil outlet hole. The self-lubricating method includes clamping the pipe and mandrel, calculating the lubrication arc length of the pipe bend, setting the initial position of the pipe, and oil injection for self-lubrication. This invention effectively avoids the prolonged delay in oil injection that occurs after the oil injection device is turned off when the mandrel is long, thereby achieving precise control of the amount of lubricating oil injected and preventing excessive oil injection leading to lubricating oil leakage.

Description

Technical Field

[0001] This invention relates to the field of CNC pipe bending machine technology, specifically to a self-lubricating structure and self-lubricating method for a CNC pipe bending machine mandrel. Background Technology

[0002] With the widespread application of CNC pipe bending technology in air conditioning, automobiles, aviation, shipbuilding and other fields, pipe bending plays an increasingly important role in industrial development. Therefore, the quality and performance of pipe bending directly affect the structural performance of industrial products. However, some defects may occur during the pipe bending process, such as bending cracks and flattening.

[0003] To address the issue of flattening or cracking during pipe bending, a good method is to use a mandrel. The mandrel is placed inside the pipe's bore to support the inner wall. A typical mandrel is a flexible mandrel, whose structure consists of several spherical mandrel heads sequentially connected to the front end of a rigid mandrel via a revolute joint. When the pipe bends, these spherical mandrel heads adaptively shift within the pipe, supporting the inner wall and preventing flattening or cracking.

[0004] To reduce the friction caused by the adaptive displacement of the spherical mandrel inside the tube and protect the inner wall of the tube, a lubricating medium needs to be placed between the spherical mandrel and the inner wall of the tube. The lubricating medium is generally lubricating oil, lubricating grease, or a mixture of lubricating oil and graphite. Lubricating grease or a mixture of lubricating oil and graphite is applied manually; lubricating oil can be sprayed during tube bends. However, the above lubrication methods have the following shortcomings:

[0005] Firstly, when applying lubricant manually, too much lubricant is applied to the pipe opening and inner wall, making cleaning the pipes more troublesome, time-consuming, and labor-intensive, resulting in lower efficiency and increased costs.

[0006] Secondly, when using oil spray lubrication, the high fluidity of the lubricating oil can lead to several problems. Insufficient oil spray can damage the pipe and mandrel during bending, while excessive oil spray can cause severe oil leakage, contaminating the equipment and affecting the welding quality of subsequent pipes and other parts. Furthermore, the delayed oil flow during spray lubrication means that even after spraying stops, the remaining pressure in the oil circuit can cause continuous spraying for several seconds, affecting the precise control of the oil spray volume. Summary of the Invention

[0007] To address the aforementioned problems, this invention proposes a self-lubricating structure and method for the mandrel of a CNC pipe bending machine, aiming to overcome the shortcomings of existing mandrel lubrication methods. The specific technical solution is as follows:

[0008] A self-lubricating structure for a mandrel of a CNC pipe bending machine includes a mandrel, an oil inlet hole arranged along the axial direction of the mandrel on the mandrel, and an oil outlet hole arranged at the front end of the mandrel and communicating with the oil inlet hole. The oil outlet hole is arranged laterally relative to the oil inlet hole, and a one-way valve is provided in the oil outlet hole.

[0009] Preferably, there are multiple oil outlet holes, which are distributed at intervals along the circumference of the mandrel.

[0010] Preferably, the axis of the oil outlet is inclined forward toward the front end of the mandrel.

[0011] More preferably, an annular groove is provided on the outer circumference of the mandrel, and the nozzle of each oil outlet is connected to the annular groove.

[0012] In this invention, the mandrel is a flexible mandrel with 1 to N spherical mandrels at its front end. The first spherical mandrel among the 1 to N spherical mandrels is rotatably connected to the mandrel through a spherical rotating joint. The 1 to N spherical mandrels are rotatably connected to each other in sequence through spherical rotating joints.

[0013] A self-lubricating method for a self-lubricating structure of a CNC pipe bending machine mandrel includes the following steps:

[0014] (1) Clamping of pipe and mandrel: Install the mandrel in the inner hole of the pipe, install the pipe on the servo carriage of the CNC pipe bending machine, clamp the outer circle of the pipe by the chuck on the servo carriage, and the part of the pipe to be bent enters the pipe bending mold. The rear end of the mandrel is fixed on the CNC pipe bending machine and the oil inlet of the mandrel is connected to the oil spraying device.

[0015] (2) Calculation of lubrication arc length for pipe bending: A lubrication arc length calculation module is set in the control system of the CNC pipe bending machine. The lubrication arc length calculation module automatically calculates the arc length L that needs to be lubricated based on the bending radius and bending angle of the pipe.

[0016] (3) Setting the initial position of the tube: The servo carriage clamps the tube and moves it backward, automatically pulling the tube backward a distance A; wherein, the distance A is equal to the distance from the starting point of the tube to the nozzle position of the oil outlet of the mandrel.

[0017] (4) Oil spraying self-lubrication: After the servo carriage clamps the pipe and moves it backward a distance L, it is then fed forward a distance L and the oil spraying device is turned on during the feeding process to spray oil, thereby achieving self-lubrication of the part of the pipe to be bent.

[0018] One preferred option is that in step (4) oil spraying self-lubrication, the oil spraying time and oil spraying stop time are set by the control system of the CNC pipe bending machine. The setting mode includes using continuous oil spraying or intermittent oil spraying to achieve self-lubrication of the pipe to be bent.

[0019] The second preferred option is: in step (4) oil spraying self-lubrication, when the arc length L that needs lubrication is greater than or equal to A, the pipe moves to the starting point of the bend and begins to bend, and continues to spray oil until the bend is completed and the oil spraying stops.

[0020] The third preferred option is: in step (4) oil spraying self-lubrication, when the arc length L < A, the oil spraying stops when the oil spraying distance is equal to the arc length L, and bending begins. No oil is sprayed when bending.

[0021] The fourth preferred option is to consider the potential delay in oil spraying. After automatically calculating the arc length, oil spraying stops X millimeters before the bend is completed. For example, for a 76R171 pipe bent 180° with an arc length L = 537 mm, oil spraying stops when the bend reaches 146° (i.e., the arc length equals 537 - X millimeters). The distance X for stopping oil spraying early can be manually adjusted according to the actual situation. Similarly, when the arc length L is less than the dimension A, when the servo carriage clamps the pipe and feeds it to the starting point for synchronous oil spraying, oil spraying can be stopped early. The distance Y for stopping early can be manually set. For example, for a 76R141 pipe bent 45° with an arc length L of 110 mm and A of 150 mm, the oil spraying distance can be LY.

[0022] The fifth preferred option is that the injection time and injection stop time can be set separately and changed in a timely manner according to the actual lubrication situation, such as an injection time of 0.5 seconds followed by a 2-second pause, to precisely control the amount of oil injected.

[0023] As a further improvement of the present invention, oil return channels are provided sequentially and interconnected on the mandrel and the 1 to N spherical mandrels respectively. On the spherical surface of the last spherical mandrel among the 1 to N spherical mandrels of the flexible mandrel, a number of oil suction microholes connected to the oil return channels are densely distributed. The rear end of the oil return channel on the mandrel is connected to the negative pressure oil suction device. In the step (4) oil spraying self-lubrication, after the lubricating oil is sprayed, the excess lubricating oil inside the tube is sucked away by the oil suction microholes on the last spherical mandrel under the action of the negative pressure oil suction device and discharged backward through the oil return channel.

[0024] Preferably, the tube can be moved back and forth once between the completion of lubricant spraying and the tube bending to remove excess lubricant from the tube. To avoid excessive oil absorption affecting lubrication, a slight negative pressure is used in this case.

[0025] Preferably, during the process of separating the tube from the mandrel after the tube is bent, the negative pressure oil suction device is activated to remove oil from the inside of the tube. To improve the oil removal effect, a high negative pressure is used at this time.

[0026] Preferably, the fuel injection device is a fuel injection pump connected to the fuel inlet hole on the mandrel via a fuel injection pipeline.

[0027] Preferably, the negative pressure oil suction device is a vacuum generator connected to the oil return channel on the mandrel via a negative pressure pipeline.

[0028] Preferably, a filter element mounting hole is provided at the center of the first spherical core head, located between the oil suction micro-hole and the oil return channel, and a filter element is disposed within the filter element mounting hole. A removable filter element sealing plate is installed at the opening of the filter element mounting hole for filter element replacement.

[0029] The beneficial effects of this invention are:

[0030] First, the self-lubricating structure and method of the mandrel for a CNC pipe bending machine of the present invention includes a one-way valve installed in the oil outlet. During oil injection, the one-way valve is opened by oil pressure to achieve the injection of lubricating oil. After the oil injection device is closed, the oil pressure in the oil circuit decreases, causing the one-way valve to reset and the oil injection to stop. This can effectively avoid the phenomenon of long delay in oil injection after the oil injection device is closed when the mandrel is long, thereby achieving precise control of the amount of lubricating oil injected, and thus avoiding the phenomenon of lubricating oil dripping caused by excessive oil injection. This avoids lubricating oil pollution on the equipment site and is conducive to improving the welding quality of subsequent pipes and other parts.

[0031] Secondly, the self-lubricating structure and self-lubricating method of the CNC pipe bending machine mandrel of the present invention overcomes the disadvantages of excessive lubricating oil at the pipe opening and inner wall during manual application, which makes cleaning the pipe more troublesome, thereby improving production efficiency and reducing production costs.

[0032] Third, the self-lubricating structure and method of the CNC pipe bending machine mandrel of the present invention features a flexible mandrel with numerous oil-absorbing micropores on the spherical surface of the last spherical mandrel head. Excess lubricating oil in the pipe can be discharged through a negative pressure oil suction device and an oil return channel. This further improves the reliability of the self-lubricating oil spray operation. Furthermore, the oil return channel also facilitates the lubrication of the rotating parts on the spherical mandrel head, thereby increasing the service life of the spherical mandrel head. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a self-lubricating structure of a CNC pipe bending machine mandrel according to the present invention;

[0034] Figure 2 yes Figure 1 A schematic diagram of a further improved structure based on the existing design;

[0035] Figure 3 yes Figure 2 A magnified view of a portion of the document;

[0036] Figure 4 Is Figure 3 This is a further improved structural diagram based on the previous one.

[0037] Figure 5 This is a schematic diagram of the steps of a self-lubricating method for a self-lubricating structure of a CNC pipe bending machine mandrel according to the present invention;

[0038] In the diagram: 1. Core rod, 2. Oil inlet, 3. Oil outlet, 4. Check valve, 5. Annular groove, 6. Nozzle, 7. Spherical core head, 8. Spherical rotating pair, 9. Tube, 10. Servo carriage, 11. Oil injection device, 12. Oil suction micro-hole, 13. Oil return channel, 14. Negative pressure oil suction device, 15. Filter element, 16. Filter element sealing plate.

[0039] In the diagram: L is the arc length that needs lubrication, and A is the distance from the starting point of the pipe bend to the nozzle position of the oil outlet of the mandrel. Detailed Implementation

[0040] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0041] Example 1:

[0042] like Figures 1 to 5 The figure shows an embodiment of a self-lubricating structure for a CNC pipe bending machine mandrel according to the present invention, including a mandrel 1, an oil inlet hole 2 arranged along the axial direction of the mandrel 1 on the mandrel 1, and an oil outlet hole 3 arranged at the front end of the mandrel 1 and connected to the oil inlet hole 2. The oil outlet hole 3 is arranged laterally relative to the oil inlet hole 2, and a one-way valve 4 is provided in the oil outlet hole 3.

[0043] Preferably, there are multiple oil outlet holes 3, which are distributed at intervals along the circumference of the mandrel 1.

[0044] Preferably, the axis of the oil outlet 3 is inclined forward toward the front end of the mandrel 1.

[0045] More preferably, an annular groove 5 is provided on the outer circle of the mandrel 1, and the nozzle 6 of each oil outlet 3 is connected to the annular groove 5.

[0046] In this embodiment, the mandrel 1 is a flexible mandrel with 1 to N spherical mandrels 7 at its front end. The first spherical mandrel 7 among the 1 to N spherical mandrels 7 is rotatably connected to the mandrel 1 through a spherical rotating joint 8. The 1 to N spherical mandrels 7 are rotatably connected to each other in sequence through spherical rotating joints 8.

[0047] Example 2:

[0048] A self-lubricating method for a CNC pipe bending machine mandrel employing the self-lubricating structure of Example 1 includes the following steps:

[0049] (1) Clamping of tube and mandrel: Install mandrel 1 in the inner hole of tube 9, install tube 1 on the servo carriage 10 of CNC tube bending machine, clamp the outer circle of tube 9 by the chuck on the servo carriage 10, and the part of tube 9 to be bent enters the tube bending mold. The rear end of mandrel 1 is fixed on CNC tube bending machine and the oil inlet 2 of mandrel 1 is connected to the oil spraying device 11.

[0050] (2) Calculation of lubrication arc length for pipe bending: A lubrication arc length calculation module is set in the control system of the CNC pipe bending machine. The lubrication arc length calculation module automatically calculates the arc length L that needs to be lubricated based on the bending radius and bending angle of the pipe 9.

[0051] (3) Setting the initial position of the tube: The servo carriage 10 clamps the tube and moves it backward, automatically pulling the tube 9 backward a distance A; wherein, the distance A is equal to the distance from the starting point of the tube 9 to the nozzle 6 of the oil outlet 3 of the mandrel.

[0052] (4) Oil spraying self-lubrication: After the servo carriage 10 clamps the pipe 9 and moves it backward a distance L, it is then pushed forward a distance L and the oil spraying device 11 is turned on to spray oil during the pushing process, thereby achieving self-lubrication of the part of the pipe 9 to be bent.

[0053] One preferred option is that in step (4) oil spraying self-lubrication, the oil spraying time and oil spraying stop time are set by the control system of the CNC pipe bending machine. The setting mode includes using continuous oil spraying or intermittent oil spraying to achieve self-lubrication of the pipe to be bent.

[0054] The second preferred option is: in step (4) oil spraying self-lubrication, when the arc length L that needs lubrication is greater than or equal to A, the pipe 9 moves to the starting point of the bend and begins to bend, and continues to spray oil until the bend is completed and the oil spraying stops.

[0055] The third preferred option is: in step (4) oil spraying self-lubrication, when the arc length L < A, the oil spraying stops when the oil spraying distance is equal to the arc length L, and bending begins. No oil is sprayed when bending.

[0056] The fourth preferred option is to consider the potential delay in oil spraying. After automatically calculating the arc length, oil spraying stops X millimeters before the completion of the bend. For example, for a 76R171 pipe 9 bent 180° with an arc length L = 537 mm, oil spraying stops when the bend reaches 146° (i.e., the arc length equals 537 - X millimeters). The distance X for stopping oil spraying early can be manually adjusted according to the actual situation. Similarly, when the arc length L is less than the dimension A, when the servo carriage 10 clamps the pipe 9 and feeds it to the starting point for synchronous oil spraying, oil spraying can be stopped early. The distance Y for stopping early can be manually set. For example, for a 76R141 pipe bent 45° with an arc length L of 110 mm and A of 150 mm, the oil spraying distance can be LY.

[0057] The fifth preferred option is that the injection time and injection stop time can be set separately and changed in a timely manner according to the actual lubrication situation, such as an injection time of 0.5 seconds followed by a 2-second pause, to precisely control the amount of oil injected.

[0058] As a further improvement of this embodiment, oil return channels 13 are provided sequentially and interconnected on the mandrel and the 1 to N spherical mandrels 7. On the spherical surface of the last spherical mandrel 7 among the 1 to N spherical mandrels 7 of the flexible mandrel, there are a number of oil suction microholes 12 connected to the oil return channels 13. The rear end of the oil return channel 13 on the mandrel 1 is connected to the negative pressure oil suction device 14. In the step (4) oil spraying self-lubrication, after the lubricating oil is sprayed, the excess lubricating oil inside the tube 9 is sucked away by the oil suction microholes 12 on the last spherical mandrel 7 under the action of the negative pressure oil suction device 14 and discharged backward through the oil return channel 13.

[0059] Preferably, the pipe 9 can be moved back and forth once between the completion of lubricant spraying and the bending of the pipe 9 to remove excess lubricant from the pipe 9. To avoid excessive oil absorption affecting lubrication, a slight negative pressure is used in this case.

[0060] Preferably, during the process of separating the tube 9 from the mandrel 1 after the tube 9 has been bent, the negative pressure oil suction device 14 is also activated to remove oil from the inside of the tube 9. To improve the oil removal effect, a high negative pressure is used at this time.

[0061] Preferably, the fuel injection device 11 is a fuel injection pump connected to the fuel inlet 2 on the mandrel 1 via a fuel injection pipeline.

[0062] Preferably, the negative pressure oil suction device 14 is a vacuum generator connected to the oil return channel 13 on the mandrel 1 via a negative pressure pipeline.

[0063] Preferably, a filter element mounting hole is provided at the center of the first spherical core head 7 between the oil suction micro-hole 12 and the oil return channel 13, and a filter element 15 is disposed in the filter element mounting hole. A removable filter element sealing plate 16 is installed at the opening of the filter element mounting hole for replacement of the filter element 15.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A self-lubricating method for a self-lubricating structure of a CNC pipe bending machine mandrel, characterized in that, The self-lubricating structure includes a mandrel, an oil inlet hole arranged axially on the mandrel, and an oil outlet hole arranged at the front end of the mandrel and communicating with the oil inlet hole. The oil outlet hole is arranged laterally relative to the oil inlet hole, and a one-way valve is provided in the oil outlet hole. The self-lubricating method includes the following steps: (1) Clamping of pipe and mandrel: Install the mandrel in the inner hole of the pipe, install the pipe on the servo carriage of the CNC pipe bending machine, clamp the outer circle of the pipe by the chuck on the servo carriage, and the part of the pipe to be bent enters the pipe bending mold. The rear end of the mandrel is fixed on the CNC pipe bending machine and the oil inlet of the mandrel is connected to the oil spraying device. (2) Calculation of lubrication arc length for pipe bending: A lubrication arc length calculation module is set in the control system of the CNC pipe bending machine. The lubrication arc length calculation module automatically calculates the arc length L that needs to be lubricated based on the bending radius and bending angle of the pipe. (3) Setting the initial position of the tube: The servo carriage clamps the tube and moves it backward, automatically pulling the tube backward a distance A; wherein, the distance A is equal to the distance from the starting point of the tube to the nozzle position of the oil outlet of the mandrel. (4) Oil spraying self-lubrication: After the servo carriage clamps the pipe and moves it backward a distance L, it is then fed forward a distance L and the oil spraying device is turned on during the feeding process to spray oil, thereby achieving self-lubrication of the part of the pipe to be bent. In step (4), the self-lubricating oil injection strategy is as follows: The oil spraying time and oil spraying stop time are set by the control system of the CNC pipe bending machine. The setting modes include using continuous oil spraying or intermittent oil spraying to achieve self-lubrication of the pipe to be bent. When the arc length L that needs lubrication is greater than or equal to A, the pipe moves to the starting point and begins to bend, and continues to spray oil until the bending is completed and then stops spraying oil. When the arc length L is less than A, the oil spraying stops when the oil spraying distance is equal to the arc length L, and bending begins. No oil is sprayed during bending.

2. The self-lubricating method for a self-lubricating structure of a CNC pipe bending machine mandrel according to claim 1, characterized in that, The number of oil outlet holes is multiple and they are distributed at intervals along the circumference of the mandrel.

3. The self-lubricating method for a self-lubricating structure of a CNC pipe bending machine mandrel according to claim 1, characterized in that, The axis of the oil outlet is inclined forward toward the front end of the mandrel.

4. The self-lubricating method for a self-lubricating structure of a CNC pipe bending machine mandrel according to claim 2, characterized in that, An annular groove is provided on the outer circumference of the mandrel, and the nozzle of each oil outlet is connected to the annular groove.

5. The self-lubricating method for a self-lubricating structure of a CNC pipe bending machine mandrel according to claim 1, characterized in that, The mandrel is a flexible mandrel with 1 to N spherical mandrels at the front end. The first spherical mandrel among the 1 to N spherical mandrels is rotatably connected to the mandrel through a spherical rotating joint. The 1 to N spherical mandrels are rotatably connected to each other in sequence through spherical rotating joints.

6. The self-lubricating method for a self-lubricating structure of a CNC pipe bending machine mandrel according to claim 5, characterized in that, Oil return channels are sequentially interconnected on the mandrel and the 1 to N spherical mandrels. On the spherical surface of the last spherical mandrel among the 1 to N spherical mandrels of the flexible mandrel, there are a number of oil suction microholes connected to the oil return channels. The rear end of the oil return channel on the mandrel is connected to the negative pressure oil suction device. In the oil spraying self-lubrication in step (4), after the lubricating oil is sprayed, the excess lubricating oil inside the tube is sucked away by the oil suction microholes on the last spherical mandrel under the action of the negative pressure oil suction device and discharged backward through the oil return channel.

7. The self-lubricating method for a self-lubricating structure of a CNC pipe bending machine mandrel according to claim 6, characterized in that, A filter element mounting hole is provided at the center of the first spherical core head between the oil suction micro-hole and the oil return channel, and a filter element is provided in the filter element mounting hole; a removable filter element sealing plate is installed at the opening of the filter element mounting hole for filter element replacement.

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