Non-parallel workpiece form and location tolerance detector and detection method thereof

Abstract

The invention discloses a non-parallel workpiece form and location tolerance detector and a detection method thereof. The detector comprises a programmable micro numerical control system, a reference plane precision regulation and control module, a three-dimensional rack multi-axis linkage module, a stepping motor driver module, an output type digital display dial indicator module and a data processing and interaction module. The programmable micro numerical control system is in signal connection with each module and is used for commanding linkage; the reference plane precision regulation and control module is adjusted to a preset angle through closed-loop control to bear and fix a workpiece; the three-dimensional rack multi-axis linkage module comprises a three-axis linkage structure and drives a dial indicator module at the lower end of a Z axis to scan the surface of a workpiece and collect data; the stepping motor driver module drives each stepping motor to operate; collected data is transmitted to the data processing and interaction module for analysis. According to the invention, high-precision automatic detection of the form and location tolerance of the non-parallel workpiece can be realized, the measurement stability and precision are high, manual errors can be eliminated, the efficiency is improved, the cost is reduced, and the method is suitable for quality control in the manufacturing industry.

Description

A non-parallel workpiece form and position tolerance testing instrument and its testing method Technical Field

[0001] This invention relates to a form and position tolerance testing instrument for mechanical parts, and more particularly to a form and position tolerance testing instrument for non-parallel workpieces and its testing method. Background Technology

[0002] In the manufacturing and processing of mechanical parts, geometric tolerances are key indicators for measuring the quality of the parts. To ensure the accuracy of the shape and the precision of the dimensions of the parts, various high-precision measuring tools and gauges must be used for inspection. Especially in fields involving high precision requirements such as aerospace and precision instruments, the performance of the inspection equipment directly determines whether the product meets the design standards.

[0003] The non-parallel workpieces referred to in this application are workpieces whose inspection surface is not parallel to the reference surface, but both the inspection surface and the reference surface are planar, excluding workpieces whose inspection surface is conical or complex curved. For the flatness inspection of non-parallel workpieces, traditional technical methods mainly employ the following inspection schemes: 1. Sine gauge measurement method: Using a sine gauge 2 in conjunction with an inspection platform (reference plate) 4, a dial indicator, and a gauge block set 3, the straightness and flatness of the non-parallel workpiece 1 are indirectly measured through trigonometric function relationships. Specifically, based on the known workpiece angle α and the sine gauge length L, the theoretical gauge block height H1 = L × sinα is calculated. The measurement principle of the sine gauge is shown in Figure 1.

[0004] The main disadvantages of the traditional sine gauge measurement method are: (1) Complex operation and low efficiency: Before the test, it is necessary to manually match the gauge blocks according to the calculated value to support the sine gauge. There are many components, and the dial indicator is limited in speed, so a single test takes a long time.

[0005] (2) Large cumulative error: There is contact error in the assembly of gauge blocks, and manual operation can easily introduce installation error, reading error and calculation error. For example, when using an 83-gauge block set, the actual assembly height H is often not exactly equal to the theoretical height H1 due to the limitations of the gauge block specifications (e.g., the calculated H1≈70.710678...mm, while the gauge block assembly is 70.71mm). This approximation will directly translate into angular deviation, resulting in insufficient accuracy of the measurement results.

[0006] (3) High technical threshold: Operators need to undergo professional training and master complex trigonometric function calculation, gauge block selection and measurement skills. Furthermore, subsequent data processing requires manual drawing and calculation, which is highly subjective and difficult to guarantee accuracy.

[0007] 2. Coordinate Measuring Machine (CMM) Measurement Method: As shown in Figure 2, the coordinate measuring machine (CMM) uses the main column 5 and the auxiliary column 6 as the core support, and is equipped with the X-axis bridge 7 to form a stable measurement frame. Through the multi-axis coordinated linkage of the X-axis guide rail 4, the Y-axis slide and drive component 3, and the Z-axis and drive component 2, the probe 1 is driven to move precisely in three-dimensional space. The probe 1 is used to collect the coordinate data of discrete points on the surface of the measured object by contact or non-contact. Then, the supporting software fits these discrete data into ideal geometric elements and compares and analyzes them with preset theoretical values ​​or benchmarks. Finally, it realizes a precise, repeatable, and traceable quantitative evaluation of the workpiece size and geometric tolerances, transforming the abstract geometric standard into a specific and digital measurement result.

[0008] The main disadvantages of the coordinate measuring machine (CMM) measurement method are: (1) High cost: The cost of equipment purchase, use and maintenance is extremely high, and it is difficult for small and medium-sized enterprises to popularize it; (2) High operation difficulty: Professionals need to learn the operating system and 3D modeling software for a long time, and the skill requirements for front-line inspection personnel are too high.

[0009] The invention with application number CN202311233702.X discloses a flatness measuring instrument for non-parallel workpieces, including a base, a support, a linear guide pair, a dial indicator, a dial indicator moving mechanism, and a guide rail rotating mechanism. The support is fixed on the base, one end of the guide rail of the linear guide pair is hinged to the support, and the guide rail rotating mechanism is mounted on the support. The dial indicator is fixed on the slider of the linear guide pair, and the dial indicator moving mechanism is mounted on the linear guide rail, driving the dial indicator to move linearly along the linear guide rail.

[0010] The main disadvantages of the non-parallel workpiece flatness measuring instrument of this invention are: (1) Insufficient stability and accuracy: It adopts an open-loop control mode, without real-time feedback and error compensation mechanism, and relies on multiple sets of gear transmission. The meshing gap is prone to cause motion deviation; at the same time, the stepper motor torque is insufficient, making it difficult to maintain the stability of the mechanical structure operation, which ultimately affects the measurement accuracy.

[0011] (2) Single function: It is only equipped with a linear guide rail and dial indicator moving mechanism in a single direction, and can only realize the straightness measurement in a single direction. It cannot cover the grid scanning of the two-dimensional plane and cannot fully acquire the form and position tolerance data of the workpiece surface.

[0012] (3) Large human error: The system is not equipped with an automated data acquisition and analysis system. Operators need to manually read the dial gauge values, record the data and perform subsequent calculations. In the process, multiple cumulative errors such as reading deviation, recording error and calculation error are easily introduced. Summary of the Invention

[0013] The technical problem to be solved by the present invention is to provide a non-parallel workpiece form and position tolerance measuring instrument with high measurement stability and accuracy, which is not easily affected by human operation and can be used to measure planes.

[0014] Another technical problem to be solved by the present invention is to provide a detection method for the above-mentioned non-parallel workpiece form and position tolerance detector.

[0015] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is a non-parallel workpiece form and position tolerance inspection instrument, comprising a programmable micro-numerical control system, a reference plane precision adjustment module, a three-dimensional frame multi-axis linkage module, a stepper motor driver module, an output-type digital display dial indicator module, and a data processing and interaction module; the programmable micro-numerical control system is signal-connected to the reference plane precision adjustment module, the three-dimensional frame multi-axis linkage module, the stepper motor driver module, the output-type digital display dial indicator module, and the data processing and interaction module, respectively, and is used to send control commands, receive feedback signals, plan scanning paths, and command the linkage of each module; the reference plane precision adjustment module is used to support and fix the non-parallel workpiece to be measured, and the reference plane supporting the workpiece is adjusted to a preset angle through closed-loop control under the control of the programmable micro-numerical control system; the three-dimensional frame multi-axis... The linkage module is a three-axis linkage structure of X, Y, and Z. The output-type digital display dial indicator module is detachably installed at the lower end of the Z-axis of the X, Y, and Z three-axis linkage structure. The detection station of the reference plane precision control module is arranged below the Z-axis of the X, Y, and Z three-axis linkage structure. The X, Y, and Z three-axis linkage structure is used to drive the output-type digital display dial indicator module to move along a preset path to achieve blind-spot-free scanning of the surface of the workpiece to be tested. The output-type digital display dial indicator module is used to collect the height data of the workpiece surface and transmit the collected data to the data processing and interaction module for analysis and processing. The stepper motor driver module is connected to the stepper motors of the programmable micro numerical control system, the reference plane precision control module, and the three-dimensional frame multi-axis linkage module, respectively, and is used to receive control signals and drive the corresponding stepper motors to operate.

[0016] The non-parallel workpiece form and position tolerance measuring instrument described above includes a programmable micro-controller system comprising an MCU, a motion control chip, a touch screen, multiple opto-isolated input interfaces, multiple opto-isolated output interfaces, a USB interface, an MPG interface, and an RS485 communication interface. The MPG interface is used for external pulse diagnosis, and the RS485 communication interface is used for external expansion I / O modules and analog output modules. The programmable micro-controller system adopts a motion logic hybrid control method and a Chinese-guided programming method. It achieves automatic and manual operation switching through its built-in touch screen, completes program writing, equipment operation process viewing and control, and can program a grid scanning path according to the angle and shape of the non-parallel workpiece to be measured. It controls the X, Y, and Z axes of the three-axis linkage structure to return to zero, and directs the three-dimensional frame to perform cyclic measurement actions of holding, acquiring, and moving. It also receives the acquired data transmitted by the output-type digital display dial indicator module.

[0017] The non-parallel workpiece form and position tolerance detector described above includes a stepper motor driver module comprising multiple microstepping two-phase hybrid stepper motor drivers. These drivers employ fully digital current loops for microstepping control of the spindle stepper motor of the reference plane precision control module and the stepper motor of the three-dimensional frame multi-axis linkage module. The stepper motor of the reference plane precision control module is controlled with 128x microstepping, while the stepper motors of the X, Y, and Z axes of the three-dimensional frame multi-axis linkage module are controlled with 8x microstepping.

[0018] The non-parallel workpiece form and position tolerance inspection instrument described above includes a three-dimensional frame multi-axis linkage module comprising a plate and a support serving as the base for the X, Y, and Z three-axis linkage structure. The lower end of the support is fixed on the plate, and the X, Y, and Z three-axis linkage structure is mounted on the top of the support. The reference plane precision control module includes a base, a support platform, a spindle, two bearing seats, a spindle stepper motor, and an absolute photoelectric encoder. Both ends of the spindle are supported by two bearing seats, which are mounted on the base. The spindle stepper motor and the absolute photoelectric encoder are mounted on the base. One end of the spindle is connected to the spindle stepper motor, and the other end is connected to the absolute photoelectric encoder. The support platform is fixed above the middle of the spindle, and its top surface is the reference plane. The base of the reference plane precision control module... Located on the top surface of the flat plate, the axis of the spindle is parallel to the X-axis or Y-axis of the X, Y, Z three-axis linkage structure. The spindle stepper motor is connected to the spindle stepper motor driver in the stepper motor driver module, driving the carrier platform to rotate through the spindle. The spindle stepper motor driver in the stepper motor driver module is connected to the programmable microcomputer control system (MCU) signal, receiving pulses and direction control signals from the MCU, thereby driving the spindle stepper motor to rotate the reference plane. The absolute photoelectric encoder is connected to the multi-channel opto-isolated input interface of the MCU signal. The actual angle signal of the reference plane collected by the absolute photoelectric encoder is transmitted to the motion control chip inside the MCU through the multi-channel opto-isolated input interface for angle error comparison and compensation control.

[0019] The non-parallel workpiece form and position tolerance measuring instrument described above includes an optical plate as the flat plate, and a support comprising multiple columns and two crossbeams arranged along the Y direction. The lower ends of the columns are fixed to the four corners of the top surface of the optical plate; the crossbeams are fixed to the top of the columns; the X, Y, and Z three-axis linkage structure includes an X-direction stepper motor linear module and two Y-direction stepper motor linear modules, with the two Y-direction stepper motor linear modules respectively mounted on the two crossbeams arranged along the Y direction; the two ends of the X-direction stepper motor linear module are respectively fixed to the sliders of the two Y-direction stepper motor linear modules; the Z-axis of the X, Y, and Z three-axis linkage structure includes a Z-direction stepper motor linear module and a dial indicator support, with the slider of the Z-direction stepper motor linear module vertically fixed to the slider of the X-direction stepper motor linear module; the dial indicator support is fixed to the lower end of the vertically arranged Z-direction motion mechanism of the Z-direction stepper motor linear module, and the output-type digital display dial indicator is fixed to the dial indicator support.

[0020] The non-parallel workpiece form and position tolerance testing instrument described above has a base plate, two vertical plates, and two support seats for its precision control module. The two vertical plates are fixed at both ends of the base plate along its long axis. The two support seats are separately fixed on the base plate along its long axis and located inside the two vertical plates. The spindle stepper motor is installed on the upper end of the first vertical plate, and the absolute photoelectric encoder is installed on the upper end of the second vertical plate. The bearing seat is a slide rail type bearing seat, and the bearing in the bearing seat is a graphite copper bushing bearing. The direction of the slide rail of the slide rail type bearing seat is orthogonal to the direction of the spindle axis, and the slide rail seat of the slide rail type bearing seat is fixed on the top of the corresponding support seat. The bearing platform is equipped with a workpiece positioning block and an electromagnet module. The workpiece positioning block positions the non-parallel workpiece on the bearing platform so that the intersection line of the non-parallel workpiece detection surface and the reference plane is parallel to the axis of the spindle. The electromagnet module is installed at the bottom of the bearing platform to attract and fix the non-parallel workpiece on the bearing platform.

[0021] The X-axis stepper motor and Y-axis stepper motor of the three-dimensional frame multi-axis linkage module of the non-parallel workpiece form and position tolerance inspection instrument described above work together to operate according to the grid scanning path planned by the programmable micro numerical control system. The sampling interval of the grid scanning path is set according to the workpiece size. The grid parameters of the scanning path are determined by calculation using the formulas a=(L−L0) / |L / L1|, b=(W−W0) / |W / L1|. In the formulas, a is the grid spacing related parameter in the length direction, b is the grid spacing related parameter in the width direction, L is the length dimension of the workpiece plane to be measured, W is the width dimension of the workpiece plane to be measured, L0 is the dimension value of the edge in the length direction that is not included in the detection range, W0 is the dimension value of the edge in the width direction that is not included in the detection range, and L1 is the preset sampling interval reference value. The dimension value of the edge that is not included in the detection range is the dimension of the area where no data is collected at the edge of the workpiece plane to be measured.

[0022] The non-parallel workpiece form and position tolerance measuring instrument described above has an optical flat plate with a flatness error of less than 0.01mm. The X-direction stepper motor linear module and two Y-direction stepper motor linear modules are driven by synchronous belts, while the Z-direction stepper motor linear module is driven by a ball screw. The three-dimensional frame multi-axis linkage module is equipped with XYZ-axis limit switches. These limit switches are connected to the programmable micro numerical control system and are used to limit the movement of the X, Y, and Z axes respectively, and provide a zero-return positioning reference for each axis. When the three-dimensional frame multi-axis linkage module drives the output digital display dial indicator to perform scanning, it follows a measurement cycle of Z-axis descent contact, holding for 0.5 seconds to eliminate vibration, data acquisition, and moving to the next point. A set preload is applied when the Z-axis contacts the workpiece surface.

[0023] The non-parallel workpiece form and position tolerance testing instrument described above has a data processing and interaction module that is a computer module. The computer module records measurement data through software, performs data calculations, and outputs a comprehensive analysis report that includes the full value distribution, maximum value, minimum value, average value, standard deviation, pass rate, out-of-tolerance rate, and plane accuracy grade. The plane accuracy grade is evaluated according to the relevant ISO1101 standard.

[0024] A method for detecting the above-mentioned non-parallel workpiece form and position tolerances includes the following steps: 101) System initialization and workpiece clamping: The operator starts the equipment through the touch screen of the programmable micro-numerical control system. The system performs mechanical zeroing operation on the X, Y, and Z axes. Then, the non-parallel workpiece to be tested is placed on the reference plane of the bearing platform of the reference plane precision control module and fixed by electromagnet adsorption; 102) Reference plane precision angle setting: The operator inputs the detection angle specified in the workpiece drawing into the system. The programmable micro-numerical control system calculates the number of drive pulses of the spindle stepper motor according to the preset angle. The stepper motor driver module controls the motor to drive the platform to rotate. The absolute value photoelectric encoder monitors the actual angle of the platform in real time and feeds it back to the system. The system compares the actual angle with the set angle and detects errors. When the error exceeds the set value, a compensation pulse is output for fine-tuning until the error stabilizes within the set value range; 103) Three-dimensional adaptive grid scanning and data acquisition: The programmable micro-NC system controls the X and Y axis motors to move the output type digital display dial indicator above the scanning start point. The Z axis descends so that the probe of the output type digital display dial indicator contacts the workpiece surface and applies the set preload. Then, it enters the hold, acquisition, and movement cycle. After completing the grid scanning of the entire workpiece surface, the Z axis rises, and the X and Y axes return to the origin; 104) Intelligent data analysis and report generation: The data acquisition controller in the output type digital display dial indicator module transmits discrete height data to the data processing and interaction module. The data processing and interaction module completes data statistics, tolerance judgment, and accuracy level evaluation through built-in algorithms and generates a comprehensive analysis report.

[0025] The non-parallel workpiece form and position tolerance detector and its detection method of the present invention can realize high-precision automated detection of non-parallel workpiece form and position tolerances, with high measurement stability and accuracy, can eliminate human error, improve efficiency, reduce costs, and are suitable for quality control in the manufacturing industry. Attached Figure Description

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0027] Figure 1 is a schematic diagram of the principle of the automatic detection instrument for non-parallel workpiece form and position tolerances according to an embodiment of the present invention.

[0028] Figure 2 is a principle block diagram of the automatic detection instrument for non-parallel workpiece form and position tolerances according to an embodiment of the present invention.

[0029] Figure 3 is a perspective view of the reference plane precision control module according to an embodiment of the present invention.

[0030] Figure 4 is a perspective view of the reference plane precision control module in an embodiment of the present invention from another angle.

[0031] Figure 5 is a front view of the reference plane precision control module according to an embodiment of the present invention.

[0032] Figure 6 is a perspective view of the three-dimensional rack multi-axis linkage module according to an embodiment of the present invention.

[0033] Figure 7 is a perspective view of the three-dimensional rack multi-axis linkage module of an embodiment of the present invention from another angle.

[0034] Figure 8 is a front view of the X, Y, Z three-axis linkage structure and bracket of an embodiment of the present invention.

[0035] Figure 9 is a top view of the X, Y, Z three-axis linkage structure and support of an embodiment of the present invention.

[0036] Figure 10 is a schematic diagram of the grid scanning path according to an embodiment of the present invention.

[0037] List of reference numerals: 1 - Spindle stepper motor, 2 - Spindle, 3 - Bearing housing (slide rail type bearing housing), 3-1 - Slide rail, 3-2 - Slide rail seat, 4 - Absolute photoelectric encoder (15bit / 15-bit), 5 - Base plate (base plate of the reference plane precision control module), 6 - Bearing platform, 61 - Reference plane, 7 - Support base, 8, 12 - Vertical plate, 9 - Workpiece X-direction positioning plate (workpiece positioning stop), 10 - Workpiece Y-direction positioning plate (workpiece positioning stop), 11 - Electromagnet module, 20 - X, Y, Z three-axis linkage structure, 21 - X-direction stepper motor linear module, 211 - Slider of X-direction stepper motor linear module, 22 - Y-direction stepper motor linear module, 221 - Slider of Y-direction stepper motor linear module, 23 - Z-direction stepper motor linear module, 231 - Slider of Z-direction stepper motor linear module, 232 - Ball screw, 24 - Dial indicator support, 30 - Bracket, 31 - Optical flat plate (3D rack multi-axis linkage module base plate), 32 - Column, 321 - Column support, 33 - Crossbeam, L - Dimension of the workpiece in the length direction of the plane to be measured, W - Dimension of the workpiece in the width direction of the plane to be measured, L0 - Dimension value of the edge in the length direction not included in the detection range, W0 - Dimension value of the edge in the width direction not included in the detection range, L1 - Preset sampling interval reference value, a - Parameters related to the grid spacing in the length direction, b - Parameters related to the grid spacing in the width direction Detailed Implementation

[0038] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0039] The structure and working principle of the automatic inspection instrument for non-parallel workpiece form and position tolerances according to embodiments of the present invention are shown in Figures 1 to 10.

[0040] I. The overall structure of the testing instrument is shown in Figures 1 and 2. The automatic testing instrument for non-parallel workpiece form and position tolerance of the present invention includes a programmable micro numerical control system, a reference plane precision control module, a three-dimensional frame multi-axis linkage module, a stepper motor driver module, an output type digital display dial indicator module, and a data processing and interaction module.

[0041] 1. The connection relationship of each module is shown in Figure 1 and Figure 2. The programmable micro numerical control system is connected to the reference plane precision control module, the three-dimensional frame multi-axis linkage module, the stepper motor driver module, the output type digital display dial indicator module, and the data processing and interaction module. It is used to send control commands, receive feedback signals, receive the collected data transmitted by the output type digital display dial indicator module, plan the scanning path, and command the linkage of each module.

[0042] The stepper motor driver module is connected to the stepper motors of the programmable micro numerical control system, the reference plane precision control module, and the three-dimensional frame multi-axis linkage module, respectively, and is used to receive control signals and drive the corresponding stepper motors to operate.

[0043] The output-type digital dial indicator module is used to collect height data of the workpiece surface and transmit the collected data to the data processing and interaction module for analysis.

[0044] 2. Positional Relationship of Each Module: The three-dimensional frame multi-axis linkage module includes an X, Y, and Z-axis linkage structure. The output-type digital display dial indicator module is detachably installed at the lower end of the Z-axis of the X, Y, and Z-axis linkage structure. The detection station of the reference plane precision control module is located below the Z-axis of the X, Y, and Z-axis linkage structure. The three-dimensional frame multi-axis linkage module is used to drive the output-type digital display dial indicator module to move along a preset path, realizing blind-zone-free scanning of the surface of the workpiece to be measured.

[0045] The reference plane precision adjustment module is used to support and fix the non-parallel workpiece to be measured. The reference plane supporting the workpiece is adjusted to a preset angle through closed-loop control under the control of the programmable micro numerical control system.

[0046] II. Specific Structure and Parameters of Each Module (I) Programmable Micro Numerical Control System The programmable micro numerical control system adopts the M3A series micro numerical control system, including MCU, motion control chip, touch screen, multi-channel opto-isolated input interface, multi-channel opto-isolated output interface, USB interface, MPG interface and RS485 communication interface.

[0047] 1. Hardware Parameters: The touch screen is a 7-inch color touch screen with a resolution of 800×480; the MPG interface is used for external hand pulse connection for easy manual fine-tuning of the device; the RS485 communication interface is used for external expansion IO modules and analog output modules to meet the system's functional expansion needs.

[0048] 2. Control Method and Functions: The programmable micro-NC system adopts a hybrid motion logic control method and a Chinese-guided programming method. Automatic and manual operation switching is achieved through its built-in touchscreen display. Operators can program, view and control the equipment operation process via the touchscreen. They can also program grid scanning paths based on the angle and dimensions of the non-parallel workpiece to be measured, control the zeroing of each axis of the X, Y, and Z three-axis linkage structure, and command the 3D gantry to perform cyclic measurement actions of holding, acquiring, and moving.

[0049] (ii) Stepper motor driver module As shown in Figure 2, the stepper motor driver module includes multiple microstepping two-phase hybrid stepper motor drivers, specifically the TC8642 stepper motor driver. This driver is a microstepping two-phase hybrid stepper motor driver, which uses a fully digital current loop for microstepping control. The motor has small torque fluctuation, smooth low-speed operation, low vibration and noise, and high positioning accuracy.

[0050] The driver uses a fully digital current loop for microstepping control of the spindle stepper motor of the reference plane precision control module and the stepper motor of the three-dimensional rack multi-axis linkage module. Specifically, the stepper motor of the reference plane precision control module is controlled by 128 times microstepping, and the stepper motors of the X-axis, Y-axis and Z-axis of the three-dimensional rack multi-axis linkage module are controlled by 8 times microstepping.

[0051] Based on the stepper motor's 1.8° step angle calculation, the spindle stepper motor's rotational accuracy after 128x subdivision is 1.8° / 128 = 0.014° < 0.02°. The X and Y axes use synchronous belts with a pitch circle diameter of 10mm, coupled with 8x subdivision drive. The theoretical pulse equivalent is π×10×1.8° / (8×360°)≈0.019mm, and the positioning accuracy is better than 0.02mm, meeting the stepping requirements of grid scanning.

[0052] (III) Precision Control Module for the Reference Plane 1. The overall structure is shown in Figures 2 to 5. The precision control module for the reference plane includes a base, a support platform 6, a spindle 2, two bearing seats 3, a spindle stepper motor 1, and an absolute photoelectric encoder 4. Both ends of the spindle 2 are supported by two bearing seats 3, which are mounted on the base. The spindle stepper motor 1 and the absolute photoelectric encoder 4 are mounted on the base. One end of the spindle 2 is connected to the spindle stepper motor 1, and the other end is connected to the absolute photoelectric encoder 4. The support platform 6 is fixed above the middle of the spindle 2, and its top surface is the reference plane 61.

[0053] The base plate 5 of the reference plane precision control module sits on the top surface of the flat plate of the three-dimensional frame multi-axis linkage module, below the Z-axis of the X, Y, and Z three-axis linkage structure. The axis of the spindle 2 of the reference plane precision control module is parallel to the X-axis or Y-axis of the X, Y, and Z three-axis linkage structure. The spindle stepper motor 1 is connected to the spindle stepper motor driver in the stepper motor driver module, driving the carrier platform 6 to rotate through the spindle 2. The spindle stepper motor driver in the stepper motor driver module is connected to the programmable microcomputer control system, receiving pulses and direction control signals from the programmable microcomputer control system, thereby driving the spindle stepper motor 1 to rotate the reference plane 61.

[0054] 2. Base and Bearing Seat Details: The base of the precision control module for the reference plane includes a base plate 5, two upright plates 8 and 12, and two support seats 7. The two upright plates 8 and 12 are fixed to the front and rear ends of the base plate 5 along the long axis, respectively. The two support seats 7 are fixed separately on the base plate 5 along the long axis and are located inside the two upright plates 8 and 12. The spindle stepper motor 1 is installed on the upper end of the upright plate 8, and the absolute photoelectric encoder 4 is installed on the upper end of the upright plate 12.

[0055] The bearing housing 3 is a slide rail type bearing housing, and the bearing in the bearing housing 3 is a graphite copper bushing bearing. The direction of the slide rail 3-1 in the slide rail type bearing housing is orthogonal to the direction of the axis of the main shaft 2. The slide rail 3-2 of the slide rail type bearing housing is fixed on the top of the corresponding support 7.

[0056] 3. The workpiece positioning and fixing component, the support platform 6, is equipped with a workpiece positioning block and an electromagnet module 11. The workpiece positioning block positions the non-parallel workpieces on the support platform 6. The workpiece positioning block includes a workpiece X-direction positioning plate 9 and a workpiece Y-direction positioning plate 10, ensuring that the intersection line of the non-parallel workpiece detection surface and the non-parallel workpiece reference surface is parallel to the axis of the spindle. The electromagnet module 11 is installed at the bottom of the support platform 6 to attract and fix the non-parallel workpieces clamped on the support platform 6, preventing workpiece displacement during measurement.

[0057] 4. Closed-loop control related components and logic: The absolute photoelectric encoder 4 is a 15-bit absolute photoelectric encoder, which is connected to the multi-channel opto-isolated input interface of the programmable micro numerical control system. The actual angle signal of the reference plane collected by the absolute photoelectric encoder 4 is transmitted to the motion control chip inside the programmable micro numerical control system through the multi-channel opto-isolated input interface for angle error comparison and compensation control.

[0058] The spindle stepper motor 1 is a 200-step / revolution specification. During installation and debugging, a dial indicator is used to zero the reference plane 61 on the support platform 6, and the absolute photoelectric encoder 4 is set to zero. During operation, the programmable micro numerical control system drives the spindle stepper motor 1 to rotate the reference plane 61 on the support platform 6 to the target angle. The absolute photoelectric encoder 4 reads the actual angle value of the reference plane 61 in real time and feeds it back to the system. The system compares the actual value with the preset angle value. If the error exceeds 0.02°, the system automatically sends a compensation pulse to the driver to fine-tune the rotation of the spindle stepper motor 1 until the error stabilizes within the allowable range of 0.02°.

[0059] (iv) Three-dimensional rack multi-axis linkage module 1. Overall structure The three-dimensional rack multi-axis linkage module has an optical plate 31 and a bracket 30 as the base of the X, Y, Z three-axis linkage structure 20. The lower end of the bracket 30 is fixed on the plate 1, and the X, Y, Z three-axis linkage structure 20 is installed on the top of the bracket 30.

[0060] The optical plate 31 has dimensions of 400mm×400mm×10mm, and the flatness error of the top surface of the optical plate 31 is less than 0.01mm. The support 30 includes 4 columns 32 and 4 crossbeams 33. The lower ends of the 4 columns 32 are fixed to the four corners of the top surface of the optical plate 31 by column supports 321. The 4 crossbeams 33 are fixed to the top of the 4 columns 32 to form a rectangular frame structure.

[0061] 2. The details of the three-axis linkage structure are shown in Figures 6 to 9. The X, Y, Z three-axis linkage structure 20 includes an X-direction stepper motor linear module 21 and two Y-direction stepper motor linear modules 22. The two Y-direction stepper motor linear modules 22 are respectively mounted on two crossbeams 33 arranged along the Y direction. The two ends of the X-direction stepper motor linear module 21 are respectively fixed on the sliders 221 of the two Y-direction stepper motor linear modules 22.

[0062] The Z-axis of the X, Y, Z three-axis linkage structure 20 includes a Z-direction stepper motor linear module 23 and a dial indicator support 24. The slider 231 of the Z-direction stepper motor linear module 23 is vertically fixed on the slider 211 of the X-direction stepper motor linear module 21. The dial indicator support 24 is fixed at the lower end of the vertically arranged Z-direction motion mechanism of the Z-direction stepper motor linear module 23, and the output type digital display dial indicator is fixed on the dial indicator support 24.

[0063] The X-axis stepper motor linear module 21 and the two Y-axis stepper motor linear modules 22 are driven by synchronous belts, while the Z-axis stepper motor linear module 23 is driven by a ball screw 232 to ensure the static stability of the Z-axis.

[0064] 3. Limit Switches and Functional 3D Frame Multi-Axis Linkage Module: The XYZ axis limit switches are connected to the programmable micro numerical control system and are used to limit the travel of the X, Y, and Z axes respectively, and provide a zero-return positioning reference for each axis to ensure that the movement range is within the safe limits.

[0065] 4. The X, Y, and Z axis linkage structure of the three-dimensional frame multi-axis linkage module for grid scanning path planning works in coordination with the X-axis stepper motor and Y-axis stepper motor to move according to the grid scanning path planned by the programmable micro numerical control system. The sampling interval of the grid scanning path is set according to the workpiece size.

[0066] As shown in Figure 10, the scanning path is calculated to determine the grid parameters using the formula a=(L-L0) / |L / L1|, b=(W-W0) / |W / L1|; where a is the grid spacing parameter in the length direction, b is the grid spacing parameter in the width direction, L is the length dimension of the workpiece plane to be measured, W is the width dimension of the workpiece plane to be measured, L0 is the dimension value of the edge in the length direction that is not included in the detection range, W0 is the dimension value of the edge in the width direction that is not included in the detection range, L1 is the preset sampling interval reference value, and the dimension value of the edge that is not included in the detection range is the dimension of the area where no data is collected at the edge of the workpiece plane to be measured.

[0067] In practical applications, to ensure that the dial indicator probe can move normally on the detection surface, the 2mm edge of the non-parallel workpiece detection surface is not included in the detection range. Let the theoretical step distance, i.e. the preset sampling interval reference value L1=5mm, be taken as an example with a workpiece to be measured plane length of 30mm and width of 20mm, a=(20-2) / |20 / 5|=4.5, b=(30-2) / |30 / 5|≈4.666. For ease of calculation, the practical step distance a=b=4.5mm is taken.

[0068] 5. Scanning Action Flow: When the X, Y, and Z axis linkage structure of the multi-axis linkage module of the three-dimensional frame drives the output digital display dial indicator to perform the scanning action, it follows the measurement cycle flow of Z-axis descent contact, holding for 0.5 seconds to eliminate vibration, data acquisition, and moving to the next point. When the Z-axis contacts the workpiece surface, a preload of about 2 mm is applied to eliminate the contact gap of the probe and elastic deformation error.

[0069] (v) Output type digital display dial indicator module The output type digital display dial indicator module includes an output type digital display dial indicator, a data acquisition line, a solid-state relay and a data acquisition controller, and uses a general output type digital display dial indicator as the sensor.

[0070] This invention employs a "simulated triggering" method for automatic data acquisition. After the 3D gantry precisely positions the probe at the measurement point and maintains stability, the programmable microcomputer control system outputs a pulse signal via the I / O interface to control the instantaneous activation of a solid-state relay. The relay contacts are connected in parallel to the two ends of the dial indicator's "data output / memory" physical button, thus simulating a manual button press and triggering the dial indicator to send the currently displayed displacement value to the data acquisition controller. This solution does not require cracking the dial indicator's underlying communication protocol, offering extremely high compatibility and cost advantages.

[0071] (vi) Data processing and interaction module The data processing and interaction module is a computer module. The computer module records measurement data through software, completes data calculation, and outputs a comprehensive analysis report including the full value distribution of the scan, maximum value, minimum value, average value, standard deviation, pass rate, out-of-tolerance rate and plane accuracy level. The plane accuracy level is evaluated according to the relevant ISO1101 standard.

[0072] III. Measurement Method for Non-Parallel Workpiece Geometric Tolerances Based on the aforementioned automatic non-parallel workpiece geometric tolerance measuring instrument, this invention also discloses a measurement method for non-parallel workpiece geometric tolerances, specifically including the following steps: 1. System Initialization and Workpiece Clamping The operator starts the equipment through the touch screen of the programmable micro numerical control system. The system performs mechanical zeroing operation on the X, Y, and Z axes. The system first reads the limit switch signals of the XYZ axes to ensure the accuracy of the coordinate origin. Then, the non-parallel workpiece to be measured is placed on the reference plane of the bearing platform 6 of the reference plane precision control module. The workpiece is positioned by the workpiece positioning block so that the intersection line of the non-parallel workpiece detection surface and the reference plane is parallel to the axis of the spindle. Then, the output interface 2 of the M3A micro control system is triggered, and the electromagnet is activated to firmly attract the workpiece and prevent displacement during the measurement process.

[0073] 2. Precision Angle Setting of Reference Plane: The operator inputs the inspection angle specified in the workpiece drawing into the system. The programmable micro numerical control system calculates the number of drive pulses of the spindle stepper motor according to the preset angle, and controls the motor to drive the platform to rotate through the stepper motor driver module.

[0074] Closed-loop control intervention: A 15-bit absolute photoelectric encoder installed on the rotating shaft monitors the actual angle of the platform in real time. The actual angle signal of the reference plane collected by the absolute photoelectric encoder is transmitted to the motion control chip inside the programmable micro numerical control system through a multi-channel opto-isolated input interface. The system compares the actual angle value with the preset angle value. When the error exceeds 0.02°, it outputs a compensation pulse for fine adjustment until the error stabilizes within the range of 0.02°, thus completing the establishment of a precision reference.

[0075] 3. The programmable micro-NC system controls the X and Y axis motors to move the output digital display dial indicator above the scanning start point. The Z axis descends so that the probe of the output digital display dial indicator contacts the workpiece surface and applies a preload of about 2 mm. Then, it enters the holding, acquisition and movement cycle.

[0076] The cyclic process is as follows: ① Hold: The dial indicator pauses for approximately 0.5 seconds after reaching the grid point to eliminate vibration caused by mechanical inertia; ② Acquisition: The M3A series microcontroller system controls the switch relay to engage via output interface 1, triggering the data acquisition controller to record the current dial indicator value; ③ Movement: The system moves to the next grid point coordinate. This cycle is repeated until the entire workpiece surface has been scanned using the grid. Afterward, the Z-axis rises, and the X and Y axes return to the origin.

[0077] 4. Data Intelligent Analysis and Report Generation Output: The data acquisition controller in the digital display dial indicator module transmits discrete height data to the data processing and interaction module. The data processing and interaction module completes data statistics, tolerance judgment, and accuracy level evaluation through built-in algorithms, generating a comprehensive analysis report that includes the full value distribution of the scan, maximum value, minimum value, average value, standard deviation, pass rate, out-of-tolerance rate, and plane accuracy level. The plane accuracy level is evaluated according to the relevant ISO1101 standards.

[0078] IV. Beneficial Effects of the Invention Compared with the prior art, the automatic detection instrument and measurement method for non-parallel workpiece form and position tolerance provided in the embodiments of the present invention have the following significant beneficial effects: 1. High precision and high stability The present invention adopts a closed-loop control system composed of a stepper motor with 128-fold subdivision and a 15-bit absolute encoder. The reference angle setting accuracy is ≤0.02° and the X / Y axis positioning accuracy is ≤0.02mm, which completely eliminates the cumulative errors introduced by manual calculation, gauge block selection, installation alignment and reading, and improves the measurement stability and reliability.

[0079] 2. High efficiency and easy operation: This invention achieves "one-click" fully automatic detection. Operators only need to place the workpiece, input the angle and start the system, and the system can automatically complete the angle adjustment, scanning measurement and data analysis. Operators do not need to master professional skills such as trigonometric function calculation, gauge block assembly or 3D modeling, which greatly reduces the threshold for use and training costs.

[0080] 3. Digitalization and Traceability: This invention can construct three-dimensional scanned point cloud data in real time. After importing the data into a calculation table, multi-dimensional statistical data can be obtained. The results are presented in a comprehensive analysis report with visual charts, which facilitates data storage and traceability and meets the needs of the manufacturing industry for quality control of non-parallel parts.

[0081] 4. Excellent cost-effectiveness and compatibility Compared with expensive coordinate measuring machines, this invention uses mature industrial component integration, which can achieve the core functions of automated and high-precision detection while keeping the equipment cost at a very low level, making it easy to popularize in small and medium-sized enterprises; at the same time, the output digital display dial indicator module adopts the analog trigger acquisition method, which does not require cracking the dial indicator communication protocol and has strong compatibility.

[0082] 5. Good adaptability and scalability: The present invention adopts a modular architecture design, which is convenient for maintenance and upgrades; the control strategy combining full closed-loop / semi-closed-loop balances the accuracy of key links with the overall cost and reliability of the system, and can flexibly adjust the grid scanning path parameters according to different workpiece sizes, making it highly adaptable.

Claims

1. A non-parallel workpiece form and position tolerance testing instrument, characterized in that, The system includes a programmable micro-numerical control system, a reference plane precision control module, a three-dimensional frame multi-axis linkage module, a stepper motor driver module, an output-type digital display dial indicator module, and a data processing and interaction module. The programmable micro-numerical control system is signal-connected to the reference plane precision control module, the three-dimensional frame multi-axis linkage module, the stepper motor driver module, the output-type digital display dial indicator module, and the data processing and interaction module, respectively, and is used to send control commands, receive feedback signals, plan scanning paths, and command the linkage of each module. The reference plane precision control module is used to support and fix the non-parallel workpiece to be measured. The reference plane supporting the workpiece is adjusted to a preset angle through closed-loop control under the control of the programmable micro-numerical control system. The three-dimensional frame multi-axis linkage module has an X, Y, and Z three-axis linkage structure. The output-type digital display dial indicator module is detachably installed at the lower end of the Z-axis of the X, Y, Z three-axis linkage structure. The detection station of the reference plane precision control module is arranged below the Z-axis of the X, Y, Z three-axis linkage structure. The X, Y, Z three-axis linkage structure is used to drive the output-type digital display dial indicator module to move along a preset path to achieve blind-spot-free scanning of the surface of the workpiece to be tested. The output-type digital display dial indicator module is used to collect the height data of the workpiece surface and transmit the collected data to the data processing and interaction module for analysis and processing. The stepper motor driver module is connected to the stepper motors of the programmable micro numerical control system, the reference plane precision control module, and the three-dimensional frame multi-axis linkage module, respectively, and is used to receive control signals and drive the corresponding stepper motors to operate.

2. The non-parallel workpiece form and position tolerance testing instrument according to claim 1, characterized in that, The programmable micro numerical control system includes an MCU, a motion control chip, a touch screen, multiple opto-isolated input interfaces, multiple opto-isolated output interfaces, a USB interface, an MPG interface, and an RS485 communication interface. The MPG interface is used to connect to an external hand pulse, and the RS485 communication interface is used to connect to an external expansion I / O module and an analog output module. The programmable micro numerical control system adopts a motion logic hybrid control method and a Chinese-guided programming method. It realizes automatic and manual operation switching through its built-in touch screen, completes program writing, equipment operation process viewing and control, and can program a grid scanning path according to the angle and shape of the non-parallel workpiece to be measured. It controls the X, Y, and Z axes of the three-axis linkage structure to return to zero, and directs the three-dimensional frame to perform cyclic measurement actions of holding, acquiring, and moving. It also receives the acquired data transmitted by the output-type digital display dial indicator module.

3. The non-parallel workpiece form and position tolerance testing instrument according to claim 1, characterized in that, The stepper motor driver module includes multiple microstepping two-phase hybrid stepper motor drivers, which use fully digital current loops for microstepping control of the spindle stepper motor of the reference plane precision control module and the stepper motor of the three-dimensional rack multi-axis linkage module. The stepper motor of the reference plane precision control module is controlled by 128 times microstepping, and the stepper motors of the X-axis, Y-axis and Z-axis of the three-dimensional rack multi-axis linkage module are controlled by 8 times microstepping.

4. The non-parallel workpiece form and position tolerance testing instrument according to claim 1, characterized in that, The three-dimensional frame multi-axis linkage module includes a plate and a bracket serving as the base for the X, Y, and Z three-axis linkage structure. The lower end of the bracket is fixed on the plate, and the X, Y, and Z three-axis linkage structure is mounted on the top of the bracket. The reference plane precision control module includes a base, a support platform, a spindle, two bearing seats, a spindle stepper motor, and an absolute photoelectric encoder. Both ends of the spindle are supported by two bearing seats, which are mounted on the base. The spindle stepper motor and the absolute photoelectric encoder are mounted on the base. One end of the spindle is connected to the spindle stepper motor, and the other end is connected to the absolute photoelectric encoder. The support platform is fixed above the middle of the spindle, and its top surface is the reference plane. The base of the reference plane precision control module sits on the top surface of the plate, and the axis of the spindle is parallel to the X-axis or Y-axis of the X, Y, and Z three-axis linkage structure. The spindle stepper motor is connected to the spindle stepper motor driver in the stepper motor driver module, driving the support platform to rotate through the spindle. The spindle stepper motor driver in the stepper motor driver module is connected to the programmable microcomputer control system (MCU) and receives pulses and direction control signals from the MCU, thereby driving the spindle stepper motor to rotate the reference plane. The absolute photoelectric encoder is connected to the multi-channel opto-isolated input interface of the MCU. The actual angle signal of the reference plane collected by the absolute photoelectric encoder is transmitted to the motion control chip inside the MCU through the multi-channel opto-isolated input interface for angle error comparison and compensation control.

5. The non-parallel workpiece form and position tolerance testing instrument according to claim 4, characterized in that, The aforementioned flat panel is an optical flat panel. The support includes a plurality of columns and two crossbeams arranged along the Y direction. The lower ends of the columns are fixed to the four corners of the top surface of the optical flat panel; the crossbeams are fixed to the top of the columns. The X, Y, and Z three-axis linkage structure includes an X-direction stepper motor linear module and two Y-direction stepper motor linear modules. The two Y-direction stepper motor linear modules are respectively mounted on the two crossbeams arranged along the Y direction. The two ends of the X-direction stepper motor linear module are respectively fixed to the sliders of the two Y-direction stepper motor linear modules. The Z-axis of the X, Y, and Z three-axis linkage structure includes a Z-direction stepper motor linear module and a dial indicator support. The slider of the Z-direction stepper motor linear module is vertically fixed to the slider of the X-direction stepper motor linear module. The dial indicator support is fixed to the lower end of the vertically arranged Z-direction motion mechanism of the Z-direction stepper motor linear module, and the output-type digital display dial indicator is fixed to the dial indicator support.

6. The non-parallel workpiece form and position tolerance testing instrument according to claim 4, characterized in that, The base of the reference plane precision control module includes a base plate, two vertical plates, and two support seats. The two vertical plates are fixed at both ends of the base plate along its long axis. The two support seats are separately fixed to the base plate along its long axis and located inside the two vertical plates. The spindle stepper motor is installed at the upper end of the first vertical plate, and the absolute photoelectric encoder is installed at the upper end of the second vertical plate. The bearing seat is a slide rail type bearing seat, and the bearing in the bearing seat is a graphite copper bushing bearing. The direction of the slide rail of the slide rail type bearing seat is orthogonal to the direction of the spindle axis, and the slide rail seat of the slide rail type bearing seat is fixed to the top of the corresponding support seat. The bearing platform is equipped with a workpiece positioning block and an electromagnet module. The workpiece positioning block positions the non-parallel workpiece on the bearing platform so that the intersection line of the non-parallel workpiece detection surface and the reference plane is parallel to the axis of the spindle. The electromagnet module is installed at the bottom of the bearing platform to attract and fix the non-parallel workpiece on the bearing platform.

7. The non-parallel workpiece form and position tolerance testing instrument according to claim 1, characterized in that, The X-axis stepper motor and Y-axis stepper motor of the three-dimensional frame multi-axis linkage module are coordinated to move according to the grid scanning path planned by the programmable micro numerical control system. The sampling interval of the grid scanning path is set according to the workpiece size. The grid parameters of the scanning path are determined by calculation through formulas, where a=(L−L0) / ∣L / L1∣ and b=(W−W0) / ∣W / L1∣. In the formula, a is the grid spacing related parameter in the length direction, b is the grid spacing related parameter in the width direction, L is the length dimension of the workpiece to be measured plane, W is the width dimension of the workpiece to be measured plane, L0 is the dimension value of the edge in the length direction not included in the detection range, W0 is the dimension value of the edge in the width direction not included in the detection range, L1 is the preset sampling interval reference value, and the dimension value of the edge not included in the detection range is the dimension of the area where no data is collected at the edge of the workpiece to be measured plane.

8. The non-parallel workpiece form and position tolerance testing instrument according to claim 5, characterized in that, The flatness error of the optical flat plate is less than 0.01mm. The X-axis stepper motor linear module and the two Y-axis stepper motor linear modules are driven by synchronous belts, while the Z-axis stepper motor linear module is driven by ball screws. The three-dimensional frame multi-axis linkage module is equipped with XYZ axis limit switches. The limit switches are connected to the programmable micro numerical control system and are used to limit the movement of the X, Y, and Z axes respectively, and provide a zero-return positioning reference for each axis. When the three-dimensional frame multi-axis linkage module drives the output digital display dial indicator to perform scanning, it follows a measurement cycle of Z-axis descent contact, holding for 0.5 seconds to eliminate vibration, data acquisition, and moving to the next point. A set preload is applied when the Z-axis contacts the workpiece surface.

9. The non-parallel workpiece form and position tolerance testing instrument according to claim 1, characterized in that, The data processing and interaction module is a computer module. The computer module records measurement data through software, performs data calculations, and outputs a comprehensive analysis report including the full value distribution of the scan, maximum value, minimum value, average value, standard deviation, pass rate, out-of-tolerance rate, and plane accuracy level. The plane accuracy level is evaluated according to the relevant ISO1101 standard.

10. A detection method for the non-parallel workpiece form and position tolerance detector as described in claim 1, comprising the following steps: 101) System initialization and workpiece clamping: The operator starts the equipment through the touch screen of the programmable micro numerical control system. The system performs mechanical zeroing operation of the X, Y and Z axes. Then, the non-parallel workpiece to be measured is placed on the reference plane of the bearing platform of the reference plane precision control module and fixed by electromagnet adsorption. 102) Precision Angle Setting of Reference Plane: The operator inputs the detection angle specified in the workpiece drawing into the system. The programmable micro-NC system calculates the number of drive pulses of the spindle stepper motor according to the preset angle. The stepper motor driver module controls the motor to drive the platform to rotate. The absolute value photoelectric encoder monitors the actual angle of the platform in real time and feeds it back to the system. The system compares the actual angle with the set angle. When the error exceeds the set value, it outputs a compensation pulse for fine adjustment until the error stabilizes within the set value range. 103) Three-dimensional Adaptive Grid Scanning and Data Acquisition: The programmable micro-NC system controls the X and Y axis motors to move the output type digital display dial indicator above the scanning start point. The Z axis descends so that the probe of the output type digital display dial indicator contacts the workpiece surface and applies the set preload. Then, it enters the hold, acquisition, and movement cycle. After completing the grid scan of the entire workpiece surface, the Z axis rises and the X and Y axes return to the origin. 104) Intelligent Data Analysis and Report Generation: The data acquisition controller in the output-type digital display dial indicator module transmits discrete height data to the data processing and interaction module. The data processing and interaction module completes data statistics, tolerance determination, and accuracy level evaluation through built-in algorithms, and generates a comprehensive analysis report.

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