A large weak-rigid part combination support clamp and a clamping method thereof

Abstract

The present application provides a large weak-rigidity part combination support clamp and its clamping method, the support method is according to process parameter information, the machining process is time discrete division load step, determines the part load data of each load step;Through theoretical simulation, experimental means determine the part combination support clamp layout, support force size and clamping step;According to the division load step, the finite element simulation is carried out to obtain the support force size of each clamp under different load steps, and the optimal support force is determined to make the maximum deformation of the part below the set threshold and the deformation is minimum in the parameter adjustment range;The clamp includes a plurality of support clamp monomers, a control module;The support clamp monomer includes a base, a lifting module, a support module and a pressure sensor;The beneficial effects of the present application are that the clamping method determines the support clamp combination quantity, distribution position, clamping sequence and support force size by experimental, simulation means combined with optimization algorithm, realizes the standardization and optimization of the clamping process flow.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of machine tool fixture combination, in particular to a large weak-rigidity part combination support fixture. BACKGROUND

[0002] Most of the large parts of the equipment in the aviation field adopt thin-walled structures with high performance and light weight to meet the service requirements in extremely complex environments. Due to the large structure size of the large weak-rigidity part which is much larger than that of the general thin-walled part and the large machining allowance of the structural part, the overall process structure stiffness is low due to the thin-walled feature, and the anti-deformation and vibration suppression capability is weak, which makes it easy to produce deformation during clamping and requires multiple clamping, and cannot guarantee the repeated clamping precision, resulting in clamping difficulty.

[0003] Most of the materials of the large weak-rigidity parts in the aviation field adopt high-strength and high-temperature resistant alloys, and the force and thermal coupling effect between the tool and the workpiece during machining is serious. At the same time, the process parameters, part structure and weight change during machining make it easy to produce machining chatter during fixed clamping, resulting in machining deformation and surface quality decline, which seriously affects the machining quality control and efficiency improvement of the large weak-rigidity part. In order to suppress such phenomena, the large weak-rigidity part needs to be clamped with auxiliary support fixtures according to experience. The current auxiliary support fixture arrangement is mainly based on the experience of technical personnel and is adjusted manually, but with the continuous development of aerospace technology, the performance of the manufactured parts is continuously improved, so the auxiliary clamping needs to be optimized and adjusted to meet the higher product requirements and realize high-quality and high-quality machining. SUMMARY

[0004] Therefore, the present application provides a clamping method of a large weak-rigidity part combination support fixture, which comprises the following steps:

[0005] S1: Based on the part fixed support mode, the maximum deformation information of the clamped part of the combination support fixture is obtained by combining experimental and simulation means to establish a data set, and the optimal clamping scheme is determined, which includes the number, distribution position, clamping sequence and support force size data of the support fixture single body, and the optimal clamping scheme satisfies that the maximum deformation of the clamped part is lower than the set threshold; wherein the combination support fixture comprises a plurality of support fixture single bodies with adjustable support height and support angle;

[0006] S2: According to the optimal clamping scheme determined in step S1, the load steps of the part machining process are divided according to the time sequence and discrete time interval, the load state of the part under each load step is determined, and the load information of the part machining position in the load step is obtained;

[0007] S3: Establish a three-dimensional model of the part to be machined according to the optimal clamping scheme determined in step S1, and perform finite element simulation iteration on the machining process according to the load information of each load step in step S2 to determine the optimal support force combination of the support clamp in the load step of the part, and establish a support clamp process database;

[0008] S4: During the machining process, the support height and support angle of the support clamp unit are adjusted in the range of different load steps according to the information in the support clamp process database established in step S3 to realize the adjustment of the support force of the support clamp, and the maximum deformation value of the part in the current machining state is ensured to be the smallest.

[0009] Further, in step S1, the maximum deformation information of the combined support clamp clamped part is obtained by combining experimental and simulation means to establish a data set, and the specific steps of determining the optimal clamping scheme are as follows: the initial clamping point number and position are determined according to the part fixed support mode, the support force of the support clamp unit, the support point position information of the support clamp unit and the number of support clamp units are taken as input variables by combining experimental and finite element simulation means, a part maximum deformation threshold is set, the part maximum deformation after auxiliary support of the part is calculated by simulation, and compared with the threshold to determine the optimal support combination of the support clamp.

[0010] Further, the part load information in each load step in step S2 includes: part machining position, axial force value and direction of the part along each machine tool coordinate axis, torque value and direction, and the load information of each load step is the average value of the load in its time interval.

[0011] Further, the specific steps of determining the optimal support force combination of the support clamp in the load step of the part by performing finite element simulation iteration on the machining process according to the load information of each load step in step S2 in step S3 are as follows: the optimized support layout in step S1 is used to reestablish the finite element model, the support force size of each support clamp is determined as the initial parameter in the empty state, i.e. the clamped state after auxiliary support, the upper and lower selection values are determined to determine the parameter variation range, and the force size of each support point under the load state of the part in the different load steps is iterated by combining the finite element simulation means with the optimization algorithm, the maximum deformation of the part in the support force adjustment range is calculated, and the support force combination with the minimum value of the maximum deformation of the part in each load step is selected.

[0012] The application also provides a large weak-rigidity part combined support clamp for realizing the clamping method of the large weak-rigidity part combined support clamp.

[0013] Each support clamp unit comprises a base, a lifting module, a support module and a pressure sensor.

[0014] The base is fixed to the machine tool workbench, the lifting module is fixed to the base as a connecting component between the support module and the base, the support module is fixed to the support module;

[0015] The support module comprises a pressure sensor and a mechanical arm assembly, the mechanical arm assembly comprises a mechanical arm base, a first joint L-shaped fixing member and a first servo motor, a second joint L-shaped fixing member, a second servo motor and a support rod;

[0016] The mechanical arm base is fixed to the lifting module, the first joint L-shaped fixing member is rotationally connected to the mechanical arm base, the first servo motor is fixed to the first joint L-shaped fixing member, and the first joint L-shaped fixing member is driven to rotate relative to the mechanical arm base;

[0017] The second joint L-shaped fixing member is rotationally connected to the first joint L-shaped fixing member, the second servo motor is fixed to the second joint L-shaped fixing member, and the second joint L-shaped fixing member is driven to rotate relative to the first joint L-shaped fixing member, wherein the rotation axes of the first servo motor and the second servo motor are perpendicular to each other;

[0018] The support rod is fixed to the second joint L-shaped fixing member, the pressure sensor is fixed to the end of the support rod, and all support clamp units support the parts to be machined through the support rod; the control module is connected with the pressure sensors of all support clamp units, the lifting module, the first servo motor and the second servo motor, the pressure sensor detects the support force of the support clamp unit and transmits it to the control module, the control module compares the support force data of the support clamp unit with the database information, controls the lifting module, the first servo motor and the second servo motor to adjust the support force and the support angle of all support clamp units, so as to reduce the deformation amount of the parts in the machining process.

[0019] Further, the lifting module comprises a lifting mechanism, a ball screw, a third servo motor, a top rod and a lifting platform, the lifting platform and the base are provided with guide rails, the lifting mechanism is a scissor type lifting structure, and the two ends of the lifting mechanism are respectively fixed to the guide rails of the lifting platform and the base; the ball screw is fixed to the base, one end of the top rod is fixed to the ball screw sliding block, and the other end is connected with the cross rod of the lifting mechanism; the third servo motor moves the ball screw sliding block, and the top rod as a connecting component of the sliding block and the lifting mechanism enables the lifting platform to be raised and lowered, wherein the mechanical arm base is fixedly connected to the lifting platform, and the control module is connected with the third servo motor.

[0020] Further, the combined support clamp further comprises an upper computer, the upper computer is connected with the control module, and the upper computer displays the support shape and the support force of all support clamp units, so as to facilitate observation of the control process of the control module on all support clamp units.

[0021] The beneficial effects of the large weak-rigidity part combined support clamp and the clamping method thereof are as follows: the clamping method of the application determines the number of support clamps, the distribution position, the clamping sequence and the support force size through experiments, simulation means and optimization algorithms, realizes the standardization and optimization of the clamping process, the pressure sensor transmits the support force size in real time during the machining process, the control module compares the optimal support force combination information of the support clamp database established by simulation, dynamically adjusts the support force size of the auxiliary support clamp in the machining process, reduces the influence of the load change caused by material removal on the deformation amount of the part, improves the system stiffness of the large weak-rigidity part in the machining process, and ensures the machining quality of the part; the auxiliary support clamp support module designed by the application is a two-degree-of-freedom mechanical arm structure, which can adjust the support angle through a servo motor for the complex curved surface of the large weak-rigidity part in the field of aerospace, and realize the optimization of the part support point position and the support force direction through simulation verification, further reducing the influence of the support force on the maximum deformation of the large weak-rigidity part in the clamping process. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The flow chart of the clamping method of the large weak-rigidity part combined support clamp of the application;

[0023] Figure 2 The schematic diagram of the bowl-shaped thin-walled part;

[0024] Figure 3 The initial positioning schematic diagram of the 4-point clamping of the bowl-shaped thin-walled part;

[0025] Figure 4 The initial positioning schematic diagram of the 6-point clamping of the bowl-shaped thin-walled part;

[0026] Figure 5 The schematic diagram of the boat-shaped thin-walled part;

[0027] Figure 6 The initial positioning schematic diagram of the 6-point clamping of the boat-shaped thin-walled part;

[0028] Figure 7 The initial positioning schematic diagram of the 8-point clamping of the boat-shaped thin-walled part;

[0029] Figure 8 The first three-dimensional structure diagram of the support clamp monomer of the large weak-rigidity part combined support clamp of the application;

[0030] Figure 9 The second three-dimensional structure diagram of the support clamp monomer of the large weak-rigidity part combined support clamp of the application.

[0031] In the figure: 1, scissor lifting structure; 2, lifting platform; 3, mechanical arm base; 4, first joint L-shaped fixing piece; 5, first servo motor; 6, support rod; 7, second joint L-shaped fixing piece; 8, second servo motor; 9, third servo motor; 10, base; 11, ball screw; 12, ball screw sliding block; 13, top rod; 14, lifting mechanism cross beam; 15, control module; 16, upper computer; 17, pressure sensor. DETAILED DESCRIPTION

[0032] To make the object, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described below with reference to the drawings.

[0033] The control strategy of the large weak-rigid part combined support clamp proposed in the present application has a flow as shown in the figure, and is specifically described as follows. Figure 1

[0034] S1: For two types of parts as shown in Figure 2 and 5 , the initial number, distribution position, clamping sequence and support force size of the auxiliary support clamp combination are accurately determined according to the traditional part fixing auxiliary support method, such as Figure 3 and 6 . Through the experimental and finite element simulation combination means, the support clamp support force, support point number and position information are used as variables, the maximum deformation threshold of the part is set as the limiting condition, the support point position moving range and the support force size are set as the input variable sweeping range, the maximum deformation of the part after the auxiliary support of the part is calculated by simulation under different support force and support point position information, and compared with the threshold value. When the deformation is lower than the threshold value, the parameter information and the part deformation are reserved as a data set. After the parameter range calculation is completed, the number of support points is changed, such as Figure 4 and 7 , and the simulation is performed again with different support force and support point position information, the information is stored, and the optimal support combination of the support clamp is determined. After the optimal clamping combination is determined, the part clamping sequence and steps are determined through process experiments.

[0035] S2: The support point number, position and support force information determined by S1 step are combined with the part machining process mode and flow to time-discretize the machining process, divide the load steps, determine the part machining position, the axial force value and direction of the part along each machine tool coordinate axis, the torque value and direction, and the load information of each load step is the average value of the load in its time interval, and a data set is established.

[0036] ​S3: The number and position of the auxiliary support points determined in the S1 step are used to re-model the tooling system, and the support force of each support clamp in the clamped state after the auxiliary support is determined as an initial parameter, and the upper and lower selection values are used to determine the parameter variation range, and the finite element simulation means is combined with an optimization algorithm to perform iteration on the support force of each support point in the loaded state of the part in different load steps according to the load information obtained in the S2 step, and the maximum deformation value of the part in the support force adjustment range is calculated, when the maximum deformation value is lower than the deformation threshold, the current support force information is stored, and when the maximum deformation value is higher than the deformation threshold, the next set of support force parameters is selected to re-perform simulation, and the support force combination with the minimum maximum deformation value of the part in each load step is selected, and the support force combination is determined as the optimal support force combination of the support clamp in each load step of the part, and a support clamp process database is established.

[0037] S4: The support part of the clamp is provided with a pressure sensor 17, and during the machining process, the control module 15 receives the support force information of the pressure sensor 17 in real time, compares the support force information transmitted by the sensor III in the current load step with the support force data in the database established in the S3 step, and if it does not conform, adjusts the support height and support angle of the support clamp unit in different load steps to realize the adjustment of the support force of the clamp, and ensures that the maximum deformation value of the part in the current machining state is minimum.

[0038] As shown in Figure 8 , 9 The present application also provides a combined support clamp for realizing the auxiliary support of the large weak-rigidity part, which comprises a plurality of support clamp units and a control module.

[0039] Each support clamp unit comprises a support module, a lifting module, a base 10, a control module 15 and an upper computer 16. The base 10 is fixed to the machine tool workbench, and the height of the base 10 can be set according to the actual situation to adjust the lifting range of the support clamp.

[0040] The lifting module comprises a lifting mechanism, a ball screw 11, a third servo motor 9, a jacking rod 13 and a lifting platform 2, the lifting mechanism is a scissor-type lifting structure 1, the two rotating centers of the scissor-type lifting structure 1 are connected with a cross beam 14, the lifting platform 2 and the base 10 are provided with guide rails on the side edges, the lifting mechanism 1 is fixed to the guide rails of the platform 2 and the base 10 at both ends, and the height difference between the lifting platform 2 and the base 10 is changed by moving between the guide rails; the ball screw 11 is fixed to the base 10, the ball screw slider 12 is fixed with the jacking rod 13, the jacking rod 13 can rotate at the connection, and the other end of the jacking rod 13 is connected with the cross beam 14 of the lifting mechanism; the ball screw servo motor 10 moves the ball screw slider 12, and the jacking rod 13, as the connecting piece of the slider 12 and the lifting mechanism 1, drives the lifting mechanism 1 to extend and retract, so that the lifting platform 2 is raised and lowered.

[0041] The support module comprises a pressure sensor 17 and a two-degree-of-freedom mechanical arm assembly, which comprises a mechanical arm base 3, a first joint L-shaped fixing piece 4 and a first servo motor 5, a second joint L-shaped fixing piece 7 and a second servo motor 8, a support rod 6, the base 3 is fixed to the lifting module platform 2; the first servo motor 5 is fixed to the first joint L-shaped fixing piece 4, the first joint L-shaped fixing piece 4 is connected to the base 3 and the second joint L-shaped fixing piece 7 through bearings respectively, the second joint L-shaped fixing piece 7 is arranged with the second servo motor 8, the two motors and the connecting structure realize the rotation function in two directions; the support rod 6 is fixed to the other end of the second joint L-shaped fixing piece 7; the pressure sensor 17 is fixed to the front end of the support rod 6, which is used for real-time detection of the value of the support force of the support clamp when the support rod 6 assists in supporting the parts.

[0042] The control module 15 is used for receiving information of the support pressure sensor 17, comparing the information of the pressure sensor 17 with database information, adjusting servo motors (the first servo motor 5, the second servo motor 8 and the third servo motor 9) of the support module and the lifting module, changing the support force size and the support angle of the support clamp, reducing the deformation amount in the part machining process, and then changing the support force and the support direction in the support process, so as to make it meet the database support force information, ensure that the maximum deformation amount value of the current machining state part is minimum; the upper computer 16 visualizes the control process, which is convenient for observing the control process.

[0043] The specific embodiments described herein are merely illustrative of the spirit of the present application. Those skilled in the art of the present application can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, without departing from the spirit of the present application or exceeding the scope defined by the appended claims.

[0044] In this paper, the front, back, up, down and other orientation words are defined by the position of the parts in the drawing and the position of the parts relative to each other in the drawing, only to express the clarity and convenience of the technical scheme. It should be understood that the use of the orientation words should not limit the scope of the application claimed.

[0045] In the case of no conflict, the above embodiments and the features in the embodiments can be combined with each other.

[0046] The above is only the preferred embodiment of the present application, and does not limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of clamping a large weak rigid part assembly support fixture, characterized by, The method comprises the following steps: S1: Based on the part fixing support mode, the maximum deformation information of the combined support fixture clamping the part is obtained by combining experiments and simulation means to establish a data set, and the optimal clamping scheme is determined, the optimal clamping scheme comprising the number, distribution position, clamping sequence and support force size data of the support fixture single body, and the optimal clamping scheme satisfying that the maximum deformation of the part after clamping is lower than a set threshold; wherein the combined support fixture comprises a plurality of support fixture single bodies with adjustable support height and support angle; The specific steps of obtaining the maximum deformation information of the combined support fixture clamping the part by combining experiments and simulation means to establish a data set, and determining the optimal clamping scheme are as follows: the initial clamping point number and position are determined according to the part fixing support mode, the support force of the support fixture single body, the support point position information of the support fixture single body and the number of support fixture single bodies are taken as input variables by combining experimental and finite element simulation means, the maximum deformation threshold of the part is set, the maximum deformation of the part after auxiliary support is calculated by simulation, compared with the threshold, and the optimal support combination of the support fixture is determined; S2: According to the optimal clamping scheme determined in step S1, the load steps of the part machining process are divided in time sequence and discrete time interval, the part load state under each load step is determined, and the part machining position load information in the load step is obtained; The part load information under each load step comprises: part machining position, axial force value and direction of the part along each machine tool coordinate axis, torque value and direction, and the load information of each load step is the average value of the load in its time interval; S3: A three-dimensional model of the part to be machined is established according to the optimal clamping scheme determined in step S1, finite element simulation iteration is carried out on the machining process according to the load information of each load step in step S2, the optimal support force combination of the support fixture in the load step of the part is determined, and a support fixture process database is established; The specific steps of carrying out finite element simulation iteration on the machining process according to the load information of each load step in step S2 to determine the optimal support force combination of the support fixture in the load step of the part are as follows: the support layout optimized in step S1 is used to reestablish the finite element model, the support force size of each support fixture is determined as the initial parameter in the empty state, i.e. the clamping state after auxiliary support, the upper and lower selection values are used to determine the parameter change range, the finite element simulation means is combined with the optimization algorithm to carry out iteration on the force size of each support point under the part load state in different load steps, the maximum deformation of the part in the support force adjustment range is calculated, and the support force combination with the minimum value of the maximum deformation of the part in each load step is selected; S4: In the machining process, the information in the support fixture process database established in step S3 is used to adjust the support height and support angle of the support fixture single body in different load step ranges to realize the adjustment of the support force size of the fixture, and ensure that the maximum deformation value of the part in the current machining state is minimum.

2. A large weak rigid part assembly support fixture characterized by, The combined support fixture is used to realize the clamping method of the large weak-rigid part combined support fixture in claim 1; the combined support fixture comprises a plurality of support fixture single bodies and a control module. Each support clamp unit comprises a base, a lifting module, a support module and a pressure sensor; The base is fixed to the machine tool workbench, the lifting module is fixed to the base as a connecting component between the support module and the base, and the support module is fixed to the support module; The support module comprises a pressure sensor and a mechanical arm assembly, and the mechanical arm assembly comprises a mechanical arm base, a first joint L-shaped fixing part and a first servo motor, a second joint L-shaped fixing part, a second servo motor and a support rod; The mechanical arm base is fixed to the lifting module, the first joint L-shaped fixing part is rotationally connected to the mechanical arm base, the first servo motor is fixed to the first joint L-shaped fixing part, and the first joint L-shaped fixing part is driven to rotate relative to the mechanical arm base; The second joint L-shaped fixing part is rotationally connected to the first joint L-shaped fixing part, the second servo motor is fixed to the second joint L-shaped fixing part, and the second joint L-shaped fixing part is driven to rotate relative to the first joint L-shaped fixing part, wherein the rotation axes of the first servo motor and the second servo motor are perpendicular to each other; The support rod is fixed to the second joint L-shaped fixing part, the pressure sensor is fixed to the end of the support rod, and all support clamp units support the parts to be machined through the support rod; the control module is connected with the pressure sensors, the lifting modules, the first servo motors and the second servo motors of all support clamp units, the pressure sensors detect the support forces of the support clamp units and transmit the support force data to the control module, the control module compares the support force data of the support clamp units with the database information, controls the lifting modules, the first servo motors and the second servo motors to adjust the support force and the support angle of all support clamp units, so as to reduce the deformation amount of the parts in the machining process.

3. A large weak rigid part assembly support fixture according to claim 2, wherein, The lifting module comprises a lifting mechanism, a ball screw, a third servo motor, a top rod and a lifting platform, the lifting platform and the base are provided with guide rails, the lifting mechanism is a scissor type lifting structure, and the two ends of the lifting mechanism are fixed to the guide rails of the lifting platform and the base respectively; the ball screw is fixed to the base, one end of the top rod is fixed to the ball screw block, and the other end is connected with the cross rod of the lifting mechanism; the third servo motor moves the ball screw block, and the top rod, as a connecting component of the ball screw block and the lifting mechanism, enables the lifting platform to be raised and lowered, wherein the mechanical arm base is fixedly connected to the lifting platform, and the control module is connected with the third servo motor.

4. A large weak rigid part assembly support fixture according to claim 2, wherein, The combined support clamp further comprises a host computer, the host computer is connected with the control module, and the host computer displays the support shapes and the support forces of all support clamp units, so as to facilitate observation of the control process of the control module on all support clamp units.

Images