Air bag polishing machine force monitoring and collecting device and design method

Abstract

A kind of air bag polishing machine force monitoring acquisition device and design method, it is related to complex curved surface optical element high-precision polishing.The device includes force platform, S type force sensing unit, support platform, multi-channel conditioning box, force gauge and data acquisition card;Support platform is fixed on air bag polishing machine workbench;S type force sensing unit is fixed between force platform and support platform, and its fixed position and distribution are obtained by finite element software simulation according to response surface optimization method and quasi-newton method.Multi-channel conditioning box is connected with S type force sensing unit, and is connected with force gauge through signal line.Data acquisition card is connected with force gauge.Through data acquisition card, voltage signal is converted into actual force value, and is processed as compensation by Labview program, and the compensation value is transmitted to machine tool numerical control system by communication program, and the air bag is real-time compensated.The normal force of polishing is stabilized at set value, and the compensation and constant force control of polishing force are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-precision polishing of complex curved optical elements, in particular to the field of constant force polishing of air bag polishing machine tools, and especially to an air bag polishing machine tool force monitoring and collecting device and design method. BACKGROUND

[0002] Complex curved optical elements play a crucial role in high-end military and civilian fields such as laser fusion ignition devices, laser weapons, large telescopes, and lithography machines. The surface quality and shape accuracy of optical elements during polishing are of extremely high requirements.

[0003] Currently, air bag polishing machine tools can be used for polishing processing to improve processing efficiency and reduce costs. However, in order to ensure the consistency and uniformity of material removal during polishing processing, it is necessary to control the contact force between the air bag head and the workpiece during polishing. However, pure position control of the machine tool cannot achieve precise control of the polishing force, so it is necessary to install a force control device. In addition, through the force control device, the deviation of the polishing path, the repeated positioning error, and the workpiece clamping error can be adaptively compensated, thereby ensuring the quality and precision of complex curved element polishing processing. SUMMARY

[0004] The present application aims to provide a kind of air bag polishing machine tool force monitoring and collecting device and design method to solve the problem of polishing force fluctuation caused by air bag tool wear and unstable air bag polishing removal capacity during polishing, which cannot guarantee high precision, i.e., according to the comparison between the input force signal measured by the force gauge and the preset polishing force, the polishing force is compensated according to the compensation algorithm.

[0005] The present application provides an air bag polishing machine tool force monitoring and collecting device, which comprises a multi-channel conditioning box, an S-shaped force sensing unit, a force gauge, a force platform, a support platform and a data acquisition card.

[0006] The multi-channel conditioning box is used for connecting the signal lines, connecting the S-shaped force sensing unit and the force gauge together to form a channel; the multi-channel conditioning box conditions and amplifies the electrical signals received from the S-shaped force sensing unit;

[0007] The S-shaped force sensing unit is assembled with the force platform and the support platform, and is used to measure the size of the polishing force according to its deformation degree; the S-shaped force sensing unit monitors the polishing force in real time and converts the force into an electrical signal; the S-shaped force sensing unit is fixed between the force platform and the support platform, and its fixed position and distribution are obtained by finite element software simulation according to the response surface optimization method and the quasi-Newton method;

[0008] The force gauge is connected with the multi-channel conditioning box through signal lines to convert the voltage signal into an analog signal for displaying the numerical value of the polishing force; the force gauge is connected with the data acquisition card of the PC end through signal lines.

[0009] The force platform is in contact with the air bag head to bear the polishing force;

[0010] The support platform is fixed on the workbench of the air bag polisher, and the support platform is used for supporting the S-shaped force sensing unit and the force platform, and the three together constitute a force measuring device;

[0011] The data acquisition card is connected with the force gauge through a signal line, the data acquisition card collects the voltage signal, converts it into the actual force value based on the sensitivity of the sensor, and processes it into the compensation amount required for force control compensation through the Labview program.

[0012] Further, the support platform can be magnetically attracted to the workbench of the air bag polisher.

[0013] Further, the force platform is provided with a support rib plate, and each area of the force platform deforms uniformly under the action of the polishing force.

[0014] Further, the force platform and the support platform are provided with mounting grooves, and the S-shaped force sensing unit is fixed by bolts respectively, and the grooves are used to fix the S-shaped force sensing unit at the specified position.

[0015] A design method of an air bag polisher force monitoring and collecting device is used for real-time monitoring and collecting the polishing normal force, and real-time compensation is performed according to the preset polishing force to realize polishing constant force control; the specific steps of the design method can be:

[0016] 1) Demand analysis and preliminary design: clearly define the specifications and size range of the optical element to be monitored and collected, select appropriate S-shaped force sensing units, consider their sensitivity, range and accuracy; for various specifications and different sizes of optical elements, adopt the connection mode of parallel arrangement of S-shaped force sensing units;

[0017] 2) Finite element simulation optimization: based on the response surface optimization method and the quasi-Newton method, the finite element simulation software is used for optimization design of the position and arrangement of the S-shaped force sensing unit; specifically: using ANSYS Workbench or other finite element simulation software, a model of the S-shaped force sensing unit is established; the material properties, geometric parameters and boundary conditions of the model are defined; using the response surface optimization module, the first order natural frequency of the model is taken as the optimization target, and the size points arranged on the diagonal line are taken as the input parameters for optimization design; using the quasi-Newton method, the gradient information of the current size point and the quasi-Newton method matrix update rule are used to calculate the next iteration point; this process continuously and uninterruptedly searches in one dimension until the convergence criterion is met and the iteration stops; the final iteration point is the approximate optimal solution;

[0018] 3) The arrangement optimization of S-shaped force sensing unit: according to the simulation optimization result, the best arrangement scheme of S-shaped force sensing unit is determined; the stress of four S-shaped force sensing units under the polishing force of the polishing platform in any area is uniform, and the deformation of four S-shaped force sensing units is consistent.

[0019] A force monitoring and collecting method of air bag polishing machine tool, comprising the following steps:

[0020] 1) The deformation of S-shaped force sensing unit is utilized, the strain thereof is proportional to the size of external force, and the resistance value generates a resistance increment;

[0021] 2) The resistance increment is converted into voltage increment, and the voltage increment value is proportional to the load value borne by the polishing platform;

[0022] 3) After the voltage signal is collected and converted by the data acquisition card, the polishing force value acting on the polishing platform is obtained by inputting the voltage signal into the computer for processing, and the polishing force monitoring and collecting are completed.

[0023] The preset polishing force value and the fixed compensation value are input on the numerical control interface, the input polishing force signal is filtered and the average value is taken, the size of the input polishing force signal and the preset polishing force value is compared, if the difference is within the threshold range, a fixed compensation value is compensated and output, so that the compensation and constant force control relationship of the polishing force is established.

[0024] The fixed compensation value is determined by the response speed and sensitivity of the air bag polishing machine tool.

[0025] The present application is used for ensuring the smooth transition and high controllability of polishing contact force, realizing the conformal polishing of workpiece surface and constant control of contact force. The present application can realize the constant force control of polishing force, keep constant force during polishing for the same workpiece, avoid the instability of polishing contact force, the error of polishing track and the polishing force interference and error caused by the rotation and vibration of air bag tool. The present application reduces the influence of polishing force fluctuation caused by air bag tool wear during continuous polishing and the technical risk of unstable air bag polishing removal capacity caused by long time use, ensures the stability of air bag polishing process and the consistency and uniformity of material removal, ensures the quality and precision of polishing machining of complex curved surface elements. The present application can realize the real-time monitoring and automatic compensation of polishing force in the process of precision machining of optical elements, ensure the consistency and high quality of polishing effect. The present application can be widely applied in the field of precision machining and polishing, especially in the machining of optical elements. Through the present application, the machining efficiency can be improved, the waste rate can be reduced, the product quality can be improved, and the high standard requirements of various precision machining fields can be met. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic diagram of the three-dimensional structure of the present application.

[0027] Figure 2The overall decomposition schematic diagram of the present application.

[0028] Figure 3 The average deformation amount of the S-shaped force sensing unit in different installation positions.

[0029] Figure 4 The average deformation amount of the S-shaped force sensing unit installed in the position 12 shown. Figure 3

[0030] The labels of the components in the figure are as follows:

[0031] 1, A-axis swing arm; 2, B-axis swing arm; 3, air bag head; 4, multi-channel conditioning box; 5, rectangular glass workpiece; 6, S-shaped force sensing unit; 7, data acquisition card; 8, force gauge; 9, force platform; 10, support platform. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application more clear and understandable, the following embodiments will further illustrate the present application in combination with the drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0033] A kind of air bag polishing machine tool force monitoring acquisition device and design method, for real-time monitoring, acquisition polishing normal force, and according to preset polishing force is compensated in real time to realize polishing constant force control;Face all kinds of specifications and different sizes of optical elements, using the connection mode of parallel arrangement S-shaped force sensing unit, based on response surface optimization method and quasi-newton method, S-shaped force sensing unit position and arrangement are optimized and designed using finite element simulation software.In ANSYS Workbench software, using response surface optimization module to model the first order natural frequency as optimization goal, to the size point arranged on diagonal line as input parameter to carry out optimization design, using quasi-newton method according to the gradient information of current size point and quasi-newton method matrix update rule, calculate next iteration point, this process will continue and uninterruptedly one-dimensional search is carried out, until meeting convergence criterion, iteration stops, the final iteration point is the approximate optimal solution, i.e. the optimal scheme of S-shaped force sensing unit arrangement is obtained, so that four S-shaped force sensing units are uniformly stressed under the action of polishing force in any area of force platform, and four S-shaped force sensing units deform uniformly.

[0034] Referring to Figures 1-2 , the air bag polishing machine tool force monitoring acquisition device embodiment of the present application includes: A-axis swing arm 1, B-axis swing arm 2, air bag head 3;The air bag polishing machine tool force monitoring acquisition device of the present application includes a force measuring module and an acquisition module;The force measuring module includes: S-shaped force sensing unit 6, force platform 9, support platform 10;The acquisition module includes: multi-channel conditioning box 4, data acquisition card 7, force gauge 8.

[0035] ​A-axis swing arm 1 and B-axis swing arm 2 are part of the machine tool motion system, responsible for movement along the A-axis and B-axis direction, the purpose is to accurately control the position and attitude of the polishing tool; The air bag head 3 is part of the polishing tool, the air bag structure is contained inside the air bag head 3, the polishing force is controlled by adjusting the pressure in the air bag, the air bag head is in contact with the workpiece, and the polishing operation is performed;

[0036] The S-shaped force sensing unit 6 is a kind of force sensor, which can measure the size and direction of force; The S-shaped design makes it have higher sensitivity when bearing axial force.

[0037] The force measuring platform 9 and the support platform 10 are used to install and fix the force sensing unit, so that the force sensor can accurately measure the force applied by the air bag head.

[0038] The multi-channel conditioning box 4 is used to condition and amplify the received force signal, so that it is suitable for subsequent data acquisition and processing.

[0039] The data acquisition card 7 is used to convert the conditioned analog signal into a digital signal for processing and analysis by a computer or other data processing device.

[0040] The force gauge 8 is a device for displaying and recording force values, which can monitor the output of the force sensor in real time and understand the force changes during polishing.

[0041] The working process of the device: the air bag head 3 is driven by the A-axis swing arm 1 and the B-axis swing arm 2 to polish the workpiece. The S-shaped force sensing unit 6 monitors the force applied by the air bag head in real time and transmits the force signal to the multi-channel conditioning box 4. The multi-channel conditioning box 4 conditions and amplifies the signal, and then converts the analog signal into a digital signal through the data acquisition card 7. The digital signal is sent to a computer or other processing device for data analysis and processing. The force gauge 8 displays the force value in real time to help users monitor the polishing process. Figure 1 In the process, the mark 5 is a rectangular glass workpiece.

[0042] The S-shaped force sensing unit contains multiple strain gauges inside. Strain gauges are sensors that can convert mechanical deformation into electrical signals. When force acts on the S-shaped force sensing unit, the unit will undergo slight deformation, which will be sensed by the strain gauges and converted into electrical signals.

[0043] The present application utilizes the deformation of the S-shaped force sensing unit, whose strain is proportional to the size of the external force, and its resistance value produces an increment. This resistance increment is converted into a voltage increment, which is proportional to the load value borne by the force measuring platform. This voltage signal is collected and converted by the data acquisition card, and then input to the computer for processing, to obtain the polishing force value acting on the force measuring platform, and complete the monitoring and collection of the polishing force.

[0044] The force measuring platform 9 is designed with a support rib plate, and each area of the force measuring platform deforms uniformly under the action of polishing force.

[0045] The force measuring platform 9 and the support platform 10 are designed with mounting grooves, the S-shaped force sensing unit 6 is fixed by bolts respectively, and the grooves are used for fixing the S-shaped force sensing unit at a specified position.

[0046] The constant force control scheme of machine tool polishing force monitoring collection and compensation provided by the embodiment of the application is as follows:

[0047] 1) Force monitoring and collection: the S-shaped force sensing unit is used to monitor the polishing force in real time, when external force acts on the S-shaped force sensing unit, the strain gauge inside it will produce corresponding deformation, and the deformation amount is proportional to the external force. Since the resistance value of the strain gauge will increase with the deformation, the resistance increment is then converted into a voltage increment. The voltage increment value is proportional to the load value borne by the force measuring platform. The conditioning box conditions and amplifies the received voltage signal, and then the data acquisition card converts the conditioned signal into the actual force value.

[0048] 2) Force control compensation and constant force control: preset polishing force values and fixed compensation values are input on the numerical control interface, these parameters can be determined according to process requirements and experiments; the input polishing force signal is filtered to remove noise interference, and the average value is taken to obtain more stable force value data; then the average value is compared with the preset polishing force value, the difference between the two is calculated, if the difference is within the preset threshold range, it means that the current polishing force is close to the preset value, at this time a fixed compensation value is output to maintain the current force state, if the difference exceeds the threshold range, it means that the current polishing force has a large deviation from the preset value, and the compensation strategy may need to be adjusted; according to the deviation detection result, the corresponding compensation value is output, the polishing force is adjusted through the machine tool control system to make it as close to the preset value as possible, so as to realize the compensation and constant force control of the polishing force.

[0049] The compensation strategy: the collected force values are further processed and analyzed using the Labview program, the specific compensation amount required for force control compensation is calculated, the communication program developed by C# is used, the compensation value calculated is transmitted to the R10 variable of the machine tool numerical control system through the OPC UA protocol, and the machine tool temperature compensation module adjusts the downward amount of the air bag in real time according to the received compensation value. This process ensures that the polishing normal force is stable at the set value, so as to realize the compensation and constant force control of the polishing force.

[0050] Through the above steps, the polishing force can be ensured to be stable during processing, and the processing quality problem caused by force fluctuation can be reduced. Constant force control of the polishing force can be achieved, the polishing force is kept constant during polishing of the same workpiece, polishing contact force instability, polishing trajectory errors, and polishing force interference and errors caused by rotation and vibration of the air bag tool are avoided.

[0051] The fixed compensation value is determined by the response speed and sensitivity of the air bag polishing machine tool.

[0052] The operation method of the air bag polishing machine tool force monitoring and collecting device and design method of the present application is as follows:

[0053] When in use, the S-shaped force sensing unit 6 should be first installed between the force measuring platform 9 and the support platform 10, wherein the installation position of the S-shaped force sensing unit is obtained through the following simulation analysis and calculation: the S-shaped force sensing unit is sequentially arranged on the diagonals of the support platform, the average deformation of the force measuring platform when the S-shaped force sensing unit is installed at different positions on the diagonals is simulated, and the average deformation is defined as the average value of the sum of the difference between the maximum deformation and the minimum deformation of the force measuring platform under the polishing force and the polishing spot in different areas of the force measuring platform during simulation of the actual polishing, as shown in Figure 3 It can be seen that the average deformation of the force measuring platform is the smallest when the S-shaped force sensing unit is installed at position 12, as shown in Figure 4 The entire force measuring device is then adsorbed on the magnetic base. Then, the S-shaped force sensing unit 6 is connected to the multi-channel hub through the signal line, and is connected to the force gauge 8 through the signal line. The data acquisition card 7 is connected to the force gauge 8 through the signal line to collect the voltage signal, which is converted into the actual force value based on the sensitivity of the sensor, and is processed into the compensation value required for force control compensation through the Labview program algorithm. Subsequently, the communication program developed by C# is used to link the PC of the data acquisition machine box and the machine tool system, the compensation value is transmitted to the R10 value of the machine tool numerical control system through OPC UA, and the machine tool temperature compensation module is used to compensate the air bag pressure in real time. In the machine tool control system, the temperature compensation module can monitor the temperature of the machine tool and adjust the processing process according to the real-time data to ensure the accuracy and stability of the processing, wherein R10 is used to store or transmit the numerical value required for temperature compensation.

[0054] The air bag polishing constant force control of the present application adopts the fixed lifting method, that is, the input force signal is filtered and processed to take its average value, and then the difference between the input force signal and the preset polishing force is taken to determine whether the difference is within the threshold range, and if it is satisfied, a fixed amount is compensated and output. The processing quality problem caused by force fluctuation is reduced, and the consistency and stability of the polishing effect are improved.

[0055] The above embodiments are only preferred embodiments of the present application, and should not be considered as limiting the scope of the present application. Any equivalent changes and improvements made according to the scope of the present application should still belong to the patent coverage of the present application.

Claims

1. A force monitoring and acquisition device for airbag polishing machine, characterized in that include: Multi-channel conditioning box, S-type force sensitive unit, dynamometer, force measuring platform, support platform and data acquisition card; The multi-channel conditioning box is used to connect the signal lines, connecting the S-shaped force sensitive unit and the force gauge to form a path; the multi-channel conditioning box conditions and amplifies the electrical signal received from the S-shaped force sensitive unit; The S-shaped force-sensitive unit is assembled with the force-measuring platform and the support platform, and is used to measure the magnitude of the polishing force according to the degree of deformation of the S-shaped force-sensitive unit; the S-shaped force-sensitive unit monitors the polishing force in real time and converts the force into an electrical signal; the S-shaped force-sensitive unit is fixed between the force-measuring platform and the support platform, and the fixed position and distribution of the S-shaped force-sensitive unit are obtained by finite element software simulation based on the response surface optimization method and the quasi-Newton method; The dynamometer is connected to the multi-channel conditioning box via a signal line to convert the voltage signal into an analog signal to display the value of the polishing force; the dynamometer is connected to the data acquisition card on the PC via a signal line; The force measuring platform is in contact with the airbag head and is used to bear the polishing force; The support platform is fixed on the workbench of the airbag polishing machine, and is used to support the S-shaped force sensitive unit and the force measuring platform, which together constitute a force measuring device; The data acquisition card is used to connect to the dynamometer via a signal line. The data acquisition card collects voltage signals, converts them into actual force values ​​based on the sensitivity of the sensor, and processes them into compensation amounts that require force control compensation through a Labview program.

2. The force monitoring and acquisition device for an airbag polishing machine tool according to claim 1, characterized in that The supporting platform is magnetically attracted to the working table of the airbag polishing machine.

3. The force monitoring and acquisition device for an airbag polishing machine tool according to claim 1, characterized in that The force measuring platform is provided with supporting ribs, and under the action of polishing force, each area of ​​the force measuring platform deforms uniformly.

4. The force monitoring and acquisition device for an airbag polishing machine tool according to claim 1, characterized in that The force measuring platform and the supporting platform are provided with mounting grooves, and the S-shaped force sensitive units are fixed respectively by bolts, and the grooves are used to fix the S-shaped force sensitive units at designated positions.

5. The force monitoring and acquisition device for an airbag polishing machine tool according to claim 1, characterized in that The S-shaped force-sensitive units are arranged in parallel.

6. The force monitoring and acquisition device for an airbag polishing machine tool as claimed in claim 1, characterized in that The fixed position and distribution of the S-shaped force-sensitive unit are obtained by finite element software simulation based on the response surface optimization method and the quasi-Newton method, which specifically includes the following steps: 1) Use ANSYS Workbench software to build a model of the S-shaped force-sensitive element. Optimize the design using the response surface optimization module, taking the model's first-order natural frequency as the optimization target and the diagonal dimension points as input parameters. Use the quasi-Newton method to calculate the next iteration point based on the gradient information of the current dimension point and the quasi-Newton method matrix update rule. This process continues with a one-dimensional search until the convergence criterion is met and the iteration stops. The final iteration point is the approximate optimal solution. 2) Based on the simulation optimization results, determine the optimal arrangement of the S-shaped force-sensitive units; ensure that the four S-shaped force-sensitive units are evenly loaded under the polishing force in any area of ​​the force measuring platform and that the deformation of the four S-shaped force-sensitive units is consistent.

7. A method for monitoring and collecting force of an airbag polishing machine tool, characterized in that Using the airbag polishing machine tool force monitoring and acquisition device as claimed in claim 1, the method includes the following steps: 1) Using the deformation of the S-type force-sensitive unit, its strain is proportional to the magnitude of the external force, and its resistance value produces a resistance increment; 2) The resistance increment is converted into a voltage increment, and the voltage increment value is proportional to the load value borne by the force measuring platform; 3) After the voltage signal is collected and converted by the data acquisition card, it is input into the computer for processing to obtain the polishing force value acting on the force measuring platform, completing the monitoring and collection of the polishing force; 4) Real-time compensation based on the preset polishing force to achieve constant polishing force control: Enter the preset polishing force value and fixed compensation value on the CNC interface, filter the input polishing force signal and take its average value, compare the input polishing force signal with the preset polishing force value, and if the difference is within the threshold range, output a fixed compensation value, thereby establishing the compensation and constant force control relationship of the polishing force.

8. A method for monitoring and collecting force of an airbag polishing machine tool as claimed in claim 7, characterized in that In step 4), the fixed compensation value is determined by the response speed and sensitivity of the airbag polishing machine.

Images