Return section optimization method and device based on three-dimensional free bending forming

Abstract

The invention discloses a return stroke section optimization method based on three-dimensional free bending forming, which comprises the following steps: S1, obtaining an eccentric distance U of a bending die at a transition section of a pipe according to a U-R relation, and obtaining a relation function of a variable motion speed delta of the bending die and the U; s2, the axial movement speed of the bending die corresponding to each time node is calculated, meanwhile, a correction coefficient e is introduced, and finite element simulation is conducted; and S3, comparing the simulation result with the target bending member, and if the error is not in the allowable range, changing the correction parameter e to continue simulation until the error reaches the allowable range. The invention further discloses a return stroke section optimization device based on three-dimensional free bending forming. The arc length of the return stroke section is reduced, the quality and precision of a formed part are improved, and more complex pipe fittings can be machined and formed.

Description

Technical Field

[0001] The present invention relates to an advanced manufacturing technology for complex metal components, and more specifically, to a return section optimization method and device based on three-dimensional free bending forming. Background Art

[0002] At present, 3D free bending forming technology is widely used in the processing and manufacturing of complex hollow pipes required in the fields of automobiles, construction, aerospace, etc. Compared with traditional processes, a major advantage of 3D free bending forming technology is that it can realize the bending and twisting of profiles, which can realize both bending and twisting, and can easily meet the bending-twisting forming of various profile components such as large-angle bending, large-radius bending, and spiral bending.

[0003] The traditional 3D free bending forming technology divides the bent pipe into a straight section and an arc section, where the arc section is further divided into a transition section, a stable forming section, and a return section. However, in this 3D free bending forming technology, the bending die only moves in the X / Y plane, so the return section of the bent component under this scheme is relatively long, which affects the forming accuracy. The return section is directly related to the accuracy of the formed bent pipe. The return section under the current process is too long and needs to be optimized. Summary of the invention

[0004] In view of the defects existing in the prior art, the purpose of the present invention is to provide a return segment optimization method and device based on three-dimensional free bending forming, which reduces the arc length of the return segment, improves the quality and precision of the formed parts, and enables the processing and forming of more complex pipe fittings.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a return segment optimization method based on three-dimensional free bending forming, using a return segment optimization device based on three-dimensional free bending forming;

[0007] The return segment optimization device based on three-dimensional free bending forming includes an A-axis rotating motor, an X-axis motor, a bending die, a B-axis rotating motor and a Y-axis motor;

[0008] The A-axis rotating motor, the X-axis motor, the B-axis rotating motor, and the Y-axis motor control the bending die to move along the X-axis, Y-axis, A-axis, and B-axis directions;

[0009] The return segment optimization device based on three-dimensional free bending forming also includes an auxiliary shaft, which is arranged at the front end of the six-axis machine to control the bending die to move along the Z-axis direction, optimize the original return segment bending die zero return movement to the bending die zero return along the pipe, change the distance A between the center of the bending die and the front end of the guide mechanism, and reduce the arc length of the return segment.

[0010] The return section optimization method based on three-dimensional free bending forming comprises the following steps:

[0011] S1. Obtain the eccentricity U of the bending die in the transition section of the pipe according to the UR relationship, and obtain the relationship function between the variable speed motion speed δ of the bending die and U;

[0012] S2, calculating the axial movement speed of the bending die corresponding to each time node, introducing a correction coefficient e, and performing finite element simulation;

[0013] S3. Compare the simulation result with the target bending member. If the error is not within the allowable range, change the correction parameter e and continue the simulation until the error reaches the allowable range.

[0014] Preferably, the step S1 further comprises:

[0015] When the bending die is in the transition section of the pipe, the quantitative relationship between the bending radius R and the bending angle θ of the target bending member, the uniform feeding speed V of the pipe along the Z axis, the variable speed movement speed δ of the bending die along the Z axis, the movement time t, and the initial distance A from the center of the bending die to the front end of the guide mechanism is established as follows:

[0016]

[0017] When the bending die is in the return section of the pipe, the quantitative relationship between the variable speed movement speed δ of the bending die in the Z-axis direction and the initial distance A is as follows:

[0018]

[0019] The initial distance A on the transition section and the return section of the pipe is changed into a variable value.

[0020] Preferably, the step S2 further comprises:

[0021] When the bending die is in the transition section of the tube, the variable speed movement speed of the bending die in the Z-axis direction is

[0022] When the bending die is in the return section of the pipe, the variable speed movement speed of the bending die in the Z-axis direction is

[0023] The quantitative relationship after the correction coefficient e is introduced is used as the bending process parameter for finite element simulation.

[0024] Preferably, the step S3 further comprises:

[0025] The simulation results of the finite element simulation are imported into the geometric software for processing, and the dimensional difference between the simulation results and the geometric model of the target bending component is compared. If the error is not within the allowable range, the correction parameter e is changed to continue the simulation until the error reaches the allowable range. The final bending process parameters are transmitted to the six-axis machine to perform actual bending forming.

[0026] The second aspect of the present invention provides a return segment optimization device based on three-dimensional free bending forming, comprising an A-axis rotating motor, a bending die, an X-axis motor, a B-axis rotating motor and a Y-axis motor;

[0027] The A-axis rotating motor, the X-axis motor, the B-axis rotating motor, and the Y-axis motor control the bending die to move along the X-axis, Y-axis, A-axis, and B-axis directions;

[0028] The return segment optimization device based on three-dimensional free bending forming also includes an auxiliary shaft, which is arranged at the front end of the six-axis machine, controls the bending die to move along the Z-axis direction, optimizes the original return segment bending die zero return movement to the bending die zero return along the pipe, changes the distance A between the center of the bending die and the front end of the guide mechanism, and reduces the arc length of the return segment;

[0029] The return segment optimization device based on three-dimensional free bending forming realizes the return segment optimization method based on three-dimensional free bending forming provided in the first aspect of the present invention.

[0030] The present invention provides a return segment optimization method and device based on three-dimensional free bending forming. The bending die can move in the Z-axis direction through auxiliary axis control, and the original return segment zero return movement of the bending die is optimized to the bending die zero return along the pipe. The distance A between the center of the bending die and the front end of the guide mechanism is changed, the arc length of the return segment is reduced, the accuracy of the formed part is improved, and more complex pipe fittings can be processed and formed. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the flow of the return section optimization method of the present invention;

[0032] Figure 2 Schematic diagram of the pipe bending process in the return section optimization method of the present invention, (a) is when the pipe enters, (b) is when the pipe is bent, and (c) is when the pipe returns;

[0033] Figure 3 Schematic diagram of the return to zero of the bending die, (a) is before optimization, (b) is after optimization;

[0034] Figure 4 is a schematic diagram comparing the theoretical model of the target bending component and the target bending component before and after optimization;

[0035] Figure 5is a comparative schematic diagram of the target curved member before and after optimization in the embodiment of the return section optimization method of the present invention;

[0036] Figure 6 Schematic diagram of the structure of the return section optimization device of the present invention, (a) is a front view, (b) is a rear view; DETAILED DESCRIPTION

[0037] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0038] Combination Figure 1 As shown, the present invention also provides a return section optimization method based on three-dimensional free bending forming, in which an auxiliary axis 4 is added to the six-axis machine to control the Z-circumferential movement of the bending die 2, so that the six-axis machine moves with a variable A value during the forming process, that is, the A values ​​of the transition section and the return section of the tube 7 are changed, comprising the following steps:

[0039] S1. According to the UR relationship, the eccentricity U of the bending die 2 in the transition section of the tube 7 is obtained, and the relationship function between the variable speed movement speed δ of the bending die 2 and U is obtained;

[0040] S2, calculate the axial movement speed of the bending die 2 corresponding to each time node, introduce the correction coefficient e, and perform finite element simulation;

[0041] S3. Compare the simulation result with the target bending member. If the error is not within the allowable range, change the correction parameter e and continue the simulation until the error reaches the allowable range.

[0042] The above step S1 further comprises:

[0043] The quantitative relationship between the bending radius R and the bending angle θ of the target bending member, the uniform feeding speed V of the tube 7 in the Z-axis direction, the variable speed movement speed δ of the bending die 2 in the Z-axis direction, the movement time t, and the initial distance A from the center of the bending die 2 to the front end of the guide mechanism 8 is established as follows:

[0044]

[0045] When the bending die 2 is in the return section of the tube 7, the quantitative relationship between the variable speed δ of the bending die 2 in the Z-axis direction and the initial distance A is as follows:

[0046]

[0047] The initial distance A on the transition section and return section of the pipe 7 is optimized to a variable value.

[0048] The above step S2 further comprises:

[0049] When the bending die 2 is in the transition section of the tube 7, the variable speed movement speed of the bending die 2 in the Z-axis direction

[0050]

[0051] When the bending die 2 is in the return section of the tube 7, the variable speed movement speed of the bending die 2 in the Z-axis direction

[0052]

[0053] The quantitative relationship after introducing the correction coefficient e is used as the bending process parameter for finite element simulation.

[0054] The above step S3 further comprises:

[0055] The simulation results of the finite element simulation are imported into the geometry software for processing, and the dimensional differences between the simulation results and the geometric model of the target bending component are compared. If the error is not within the allowable range, the correction parameter e is changed to continue the simulation until the error reaches the allowable range. The final bending process parameters are then transmitted to the six-axis machine to perform the actual bending forming.

[0056] Combination Figure 6 As shown, the present invention also provides a return segment optimization device based on three-dimensional free bending forming, including an A-axis rotating motor 1, a bending die 2, an X-axis motor 3, an auxiliary axis 4, a B-axis rotating motor 5 and a Y-axis motor 6.

[0057] The A-axis rotating motor 1, the X-axis motor 3, the B-axis rotating motor 5, and the Y-axis motor 6 control the bending mold 2 to move along the X-axis, Y-axis, A-axis, and B-axis directions.

[0058] The auxiliary axis 4 is arranged at the front end of the six-axis machine, and controls the bending die 2 to move along the Z-axis direction, thereby optimizing the zero return movement of the bending die 2 originally on the return section 701 of the tube 7 to the zero return movement of the bending die 2 along the tube 7, changing the distance A between the center of the bending die 2 and the front end of the guide mechanism 8, and reducing the arc length of the return section 701, such as Figure 3 and Figure 4 shown.

[0059] After the stabilization forming section, the bending die 2 will return to the origin, exerting a strong force on the tube 7 during the unloading process, which will increase the cross-sectional distortion of the tube in the return section 701. Reducing the arc length of the return section 701 can suppress the cross-sectional distortion and improve the quality of the formed part. Secondly, during bending and forming, the formed part will deviate to a certain extent from the theoretical model. Reducing the return section 701 can suppress the degree of deviation and improve the accuracy of the formed part. When calculating, the return section 701 is generally included in the next straight line. The reduction of the return section 701 means that the straight section distance between the two bending sections is reduced, which enables the bending and forming of more complex pipes.

[0060] When the existing six-axis machine is working, the bending die 2 is controlled by the motor to move in the directions of the X-axis, Y-axis, A-axis and B-axis. With the return section optimization device (six-axis machine) of the present invention, under the control of the newly added auxiliary axis 4, the bending die 2 moves forward along the Z-axis direction when advancing on the transition section of the tube 7; after the stable return section ends, the tube 7 continues to advance along the axial direction, and the bending die 2 moves backward along the tube 7 in the Z-axis direction on the basis of returning to zero at the original angle.

[0061] The return segment optimization device of the present invention is used to implement the return segment optimization method of the present invention.

[0062] Example 1

[0063] The first step is to install the designed auxiliary axis 4 on the six-axis free bending and torsion equipment and debug the equipment;

[0064] In the second step, the tube 7 is installed on the six-axis free bending and twisting equipment. The bending radius R of the tube 7 is set to 200 mm, the axial feed speed is set to V = 20 mm / s, the original distance A between the center of the bending die 2 and the front end of the guide mechanism 8 is 150 mm, and the eccentricity U of the transition section is obtained according to the UR relationship:

[0065]

[0066] Among them, t1 is the duration of the transition period,

[0067] Determine the movement speed of the bending die 2 in the Z-axis direction according to the bending radius R and A:

[0068]

[0069] Among them, δ changes with time t.

[0070] The third step is to establish a three-dimensional bending model using the finite element method and introduce the rebound factor e into the quantitative relationship described in the second step;

[0071] When the bending die 2 is in the transition section of the tube 7, the moving speed of the bending die 2 in the Z-axis direction is:

[0072]

[0073] When the bending die 2 is in the return section 701 of the tube 7, the moving speed of the bending die 2 in the Z-axis direction is:

[0074]

[0075] The fourth step is to use the quantitative relationship after introducing the correction coefficient e described in the second step as the bending process parameter, perform finite element simulation, import the simulation results into the geometry software for processing, and compare the size difference between the simulation results and the geometry model until the error reaches the allowable range;

[0076] The fifth step is to transmit the final process parameters to the six-axis free bending and twisting equipment to perform the actual bending forming;

[0077] In the sixth step, the formed parts are compared with those under the same conditions before optimization. The deviation between the return section of the formed parts and the theoretical model is reduced after optimization. Figure 5 shown.

[0078] Example 2

[0079] The first step is to install the designed auxiliary axis 4 on the six-axis free bending and torsion equipment and debug the equipment;

[0080] In the second step, the tube 7 is installed on the six-axis free bending and twisting equipment. The bending radius R of the tube 7 is set to 300 mm, the axial feed speed is set to V = 20 mm / s, the original distance A between the center of the bending die 2 and the front end of the guide mechanism 8 is 150 mm, and the eccentricity U of the transition section is obtained according to the UR relationship:

[0081]

[0082] Among them, t1 is the duration of the transition period,

[0083] Determine the movement speed of the bending die 2 in the Z-axis direction according to the bending radius R and A:

[0084]

[0085] Among them, δ changes with time t.

[0086] The third step is to establish a three-dimensional bending model using the finite element method and introduce the rebound factor e into the quantitative relationship described in the second step;

[0087] When the bending die 2 is in the transition section of the tube 7, the moving speed of the bending die 2 in the Z-axis direction is:

[0088]

[0089] When the bending die 2 is in the return section 701 of the tube 7, the moving speed of the bending die 2 in the Z-axis direction is:

[0090]

[0091] The fourth step is to use the quantitative relationship after introducing the correction coefficient e described in the second step as the bending process parameter, perform finite element simulation, import the simulation results into the geometry software for processing, and compare the size difference between the simulation results and the geometry model until the error reaches the allowable range;

[0092] The fifth step is to transmit the final process parameters to the six-axis free bending and twisting equipment to perform the actual bending forming;

[0093] In the sixth step, the formed parts are compared with those under the same conditions before optimization. The deviation between the return section of the formed parts and the theoretical model is reduced after optimization. Figure 5 shown.

[0094] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A return section optimization method based on three-dimensional free bending forming, characterized in that: Adopt the return section optimization device based on three-dimensional free bending forming; The return segment optimization device based on three-dimensional free bending forming includes an A-axis rotating motor, an X-axis motor, a bending die, a B-axis rotating motor and a Y-axis motor; The A-axis rotating motor, the X-axis motor, the B-axis rotating motor, and the Y-axis motor control the bending die to move along the X-axis, Y-axis, A-axis, and B-axis directions; The return segment optimization device based on three-dimensional free bending forming also includes an auxiliary shaft, which is arranged at the front end of the six-axis machine to control the bending die to move along the Z-axis direction, optimize the original return segment bending die zero return movement to the bending die zero return along the pipe, change the distance A between the center of the bending die and the front end of the guide mechanism, and reduce the arc length of the return segment. The return section optimization method based on three-dimensional free bending forming comprises the following steps: S1. Obtain the eccentricity U of the bending die in the transition section of the pipe according to the UR relationship, and obtain the relationship function between the variable speed motion speed δ of the bending die and U; S2, calculating the axial movement speed of the bending die corresponding to each time node, introducing a correction coefficient e, and performing finite element simulation; S3. Compare the simulation result with the target bending member. If the error is not within the allowable range, change the correction parameter e and continue the simulation until the error reaches the allowable range.

2. The return section optimization method based on three-dimensional free bending forming according to claim 1 is characterized in that: The step S1 further comprises: When the bending die is in the transition section of the pipe, the quantitative relationship between the bending radius R and the bending angle θ of the target bending member, the uniform feeding speed V of the pipe along the Z axis, the variable speed movement speed δ of the bending die along the Z axis, the movement time t, and the initial distance A from the center of the bending die to the front end of the guide mechanism is established as follows: When the bending die is in the return section of the pipe, the quantitative relationship between the variable speed movement speed δ of the bending die in the Z-axis direction and the initial distance A is as follows: The initial distance A on the transition section and the return section of the pipe is changed into a variable value.

3. The return segment optimization method based on three-dimensional free bending forming according to claim 2 is characterized in that: The step S2 further comprises: When the bending die is in the transition section of the tube, the variable speed movement speed of the bending die in the Z-axis direction is When the bending die is in the return section of the pipe, the variable speed movement speed of the bending die in the Z-axis direction is The quantitative relationship after the correction coefficient e is introduced is used as the bending process parameter for finite element simulation.

4. The return segment optimization method based on three-dimensional free bending forming according to claim 3 is characterized in that: The step S3 further comprises: The simulation results of the finite element simulation are imported into the geometric software for processing, and the dimensional difference between the simulation results and the geometric model of the target bending component is compared. If the error is not within the allowable range, the correction parameter e is changed to continue the simulation until the error reaches the allowable range. The final bending process parameters are transmitted to the six-axis machine to perform actual bending forming.

5. A return section optimization device based on three-dimensional free bending forming, characterized in that: It includes A-axis rotating motor, bending die, X-axis motor, B-axis rotating motor and Y-axis motor; The A-axis rotating motor, the X-axis motor, the B-axis rotating motor, and the Y-axis motor control the bending die to move along the X-axis, Y-axis, A-axis, and B-axis directions; The return segment optimization device based on three-dimensional free bending forming also includes an auxiliary shaft, which is arranged at the front end of the six-axis machine, controls the bending die to move along the Z-axis direction, optimizes the original return segment bending die zero return movement to the bending die zero return along the pipe, changes the distance A between the center of the bending die and the front end of the guide mechanism, and reduces the arc length of the return segment; The return segment optimization device based on three-dimensional free bending forming realizes the return segment optimization method based on three-dimensional free bending forming as described in any one of claims 1-4.

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