High-precision straightness inspection device and inspection method for linear component

Abstract

The invention discloses a high-precision straightness inspection device and method for a linear component, relates to the field of measurement of slender stepped shaft type linear components, and solves the problem of inaccurate measurement caused by gravity deformation, incapability of free rotation and inconformity with vertical use conditions in existing horizontal measurement. The device comprises a rotary measuring mechanism and a laser image projection measuring tool, the rotary measuring mechanism is composed of a segmented positioning frame, a split locking disc, a rotary workbench and the like, vertical fixation and middle section reference transfer of a linear component are achieved, and the lower section coaxiality is measured in cooperation with a depth micrometer; the laser projection device comprises a laser light source, a receiving target and a control unit and drives a component to rotate through a rotary workbench, and laser projection captures upper-section swing deviation. According to the method, straightness detection is completed through reference adjustment and segmented measurement. The method fits the actual working condition, the measurement precision of the lower section is less than or equal to 0.005 mm, the measurement precision of the upper section is less than or equal to 0.002 mm, the measurement time of a 4m part is less than or equal to 30 minutes, and the method is adaptive to phi 12-phi 30 parts and is suitable for high-precision detection of vertical linear parts.

Description

Technical Field

[0001] This invention relates to the field of geometric accuracy measurement technology for linear components, specifically to a high-precision straightness inspection device and method for slender stepped shaft linear components, which is particularly suitable for straightness measurement of linear components in vertical applications. Background Technology

[0002] In the field of mechanical manufacturing, some linear components of products (such as a stepped slender shaft with a total length of about 4m and a diameter of Φ12-Φ30) are made of multiple sections welded together. The middle section has threads, and the lower section has four long strip heat dissipation plates symmetrically welded to the side of the shaft. After such components are manufactured, they must meet strict straightness requirements, and the straightness must be verified before assembly.

[0003] Existing conventional straightness inspection methods require placing the component to be inspected in a horizontal position (such as a machine tool table or testing platform) and measuring with tools such as dial indicators and micrometers. However, for the aforementioned slender stepped shaft-like linear components, this method has significant drawbacks: First, the outer surface of the component is not a fully regular cylindrical surface and has low rigidity. When arranged horizontally, it is prone to bending deformation due to gravity, requiring support points along its entire length. However, the placement of these support points interferes with the measurement points, leading to distorted measurement data. Second, the heat sink in the lower section and the threaded structure in the middle section of the component hinder its free rotation, making it impossible to achieve straightness inspection in the entire circumferential direction. Third, the component is actually used vertically, and the horizontal measurement results differ from the straightness deviation under actual working conditions, making it difficult to accurately reflect the assembly compatibility of the component.

[0004] Given the shortcomings of the existing technologies, there is an urgent need for a straightness inspection technology that can simulate the actual use state of the component (vertical), avoid the influence of gravity deformation, and achieve high-precision detection throughout the entire length, in order to solve the measurement problem of slender stepped shaft-type linear components. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing horizontal straightness measurement methods and provide a high-precision straightness inspection device and method to realize the straightness measurement of linear components in a vertical state, ensuring that the measurement results are consistent with the actual use scenario; at the same time, through reference transfer, laser projection and other technologies, the coaxiality of the upper, middle and lower sections of the linear component can be detected intuitively and efficiently, improving measurement accuracy and efficiency.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A high-precision straightness inspection device for linear components includes a rotary measuring mechanism and a laser image projection measuring tool. The rotary measuring mechanism includes a positioning frame, a locking disc, adjusting screws, lifting lugs, a central positioning pin, and a rotating worktable. The positioning frame is a segmented structure, mainly composed of four cylindrical sections connected by positioning stops, positioning pins, and fastening bolts. A cover plate is provided on the upper cylindrical end face, with its central hole matching the linear component's fixing structure. A pin hole is provided at the center of the bottom cylindrical end plate, and the central positioning pin is installed in this pin hole and the positioning pin hole at the center of the rotating worktable, making the positioning frame coaxial with the rotating worktable. Each of the four cylindrical sections of the positioning frame has a long, narrow viewing window around its perimeter. Eight measuring reference surfaces are provided on the outer end face of each viewing window, divided into two groups of four, evenly distributed circumferentially, with different heights in each group. One group has the same height as the adjusting screws and is staggered circumferentially, while the other group is located in the lower section of the positioning frame. The locking disc is a split structure with left and right semi-circular clamps, located at the center of the top cover plate of the positioning frame, used to fix the upper part of the middle section of the linear component. The locking plate is coaxial with the center hole of the cover plate, and has a lifting ring hole. Four adjusting screws are evenly distributed circumferentially at the same height in the middle of the positioning frame to adjust the distance between the middle section of the linear component and the measurement reference plane. Two lifting lugs are located on the top cover plate of the positioning frame for lifting the rotating measuring mechanism. The laser image projection measuring tool includes a laser projection light source, a laser projection receiving target, an adapter plate, a fixed frame, a square box, a control unit, and a computer. The adapter plate is installed on the fixed frame to connect the laser projection light source and the laser projection receiving target. The fixed frame is connected to the square box by bolts, and the connection point has an elongated hole structure for position adjustment. The square box is located on both sides of the rotating measuring mechanism and is fixed to the ground platform together with the rotating worktable. Both the laser projection light source and the laser projection receiving target are connected to the control unit, which is connected to the computer. The control unit supplies power to the laser projection light source and the receiving target and enables RS485 signal networking. The computer is used to display measurement values ​​in real time, record extreme values, and generate test reports.

[0008] Preferably, after the four cylindrical sections of the positioning frame are assembled, the center holes of the upper and lower end faces and the side measuring reference surfaces are precision machined as a whole to ensure that the coaxiality error of the center holes of the upper and lower end faces is ≤0.01mm and the vertical distance deviation between the measuring reference surfaces and the axis of the positioning frame is ≤0.005mm.

[0009] Preferably, the width of the elongated viewing window is 80-120mm, and the height is 2 / 3 of the height of a single section of the positioning frame. The edge of the viewing window is provided with a rounded corner transition structure to prevent scratching of linear components during installation.

[0010] Preferably, the inner sides of the left and right semi-circular clamps of the locking disc are provided with rubber buffer layers, the thickness of which is 2-3mm, to avoid damage to the outer surface of the middle section of the linear component during locking.

[0011] Preferably, the adjusting screw has a scale marking on its shank with a scale accuracy of 0.01 mm, and the screw end has a hemispherical top made of polytetrafluoroethylene.

[0012] Preferably, the length of the elongated hole structure of the fixing frame is 50-80mm, and the width is 2-3mm larger than the diameter of the connecting bolt. The inner wall of the elongated hole is provided with a lubricating coating to facilitate the adjustment of the fixing frame position.

[0013] A method for high-precision straightness inspection of linear components using the aforementioned device includes the following steps:

[0014] S1: Fix the rotary table to the ground platform using adjustable shims to complete the installation of the rotary table;

[0015] S2: Install a center positioning pin in the center hole of the rotary table;

[0016] S3: Use an overhead crane to flip the positioning frame assembly to an upright position, lift the positioning frame assembly and position it with the rotary table through the central positioning pin, and fix it with fasteners;

[0017] S4: Lift the linear component through the lifting eye hole of the locking plate, lift it to the top of the positioning frame, slowly lower it and assist the linear component's cross wings to pass through the cross notch on the upper surface of the positioning frame, so that the middle section of the linear component is in place on the upper surface of the positioning frame, and close the locking plate to fix the linear component.

[0018] S5: Using the notch on the side wall of the positioning frame, the measuring reference surface, and the adjusting screw, adjust the middle section of the linear component with a depth micrometer to make the outer cylindrical surface of the middle section equidistant from the measuring reference surface;

[0019] S6: Using the measuring reference surface of the lower section of the positioning frame and a depth micrometer, measure the distance between the outer cylindrical surface of the lower section of the linear component and the reference surface, and calculate the coaxiality deviation between the middle and lower sections of the linear component;

[0020] S7: Install the fixed frame, adapter plate, laser projection light source and laser projection receiving target of the laser image projection measuring tool on the square boxes on both sides of the rotary table. Connect the laser projection light source, receiving target and control unit through data cable. Connect the control unit to the computer. Start the special software to check the alignment and range compatibility of the laser projection light source and receiving target.

[0021] S8: Rotate the rotary table, and the dedicated software will automatically record the swing deviation of the upper section of the linear component. This deviation is the coaxiality deviation of the middle and upper sections of the linear component, thus completing the straightness check.

[0022] Preferably, in step S1, after the rotating worktable is fixed, the levelness of its end face is detected by a level instrument to ensure that the levelness is ≤0.02mm / m.

[0023] Preferably, in step S7, the alignment check method between the laser projection light source and the receiving target is as follows: finely adjust the position of the fixed frame so that the upper section of the linear component is in the middle of the measurement area, and the red and green indicator lights in the middle area of ​​the receiving target position display are not full; slowly rotate the rotating table one revolution. If the indicator lights are not full, the alignment is qualified.

[0024] Preferably, in step S4, before lifting the linear component, the outer surface of the linear component is wiped with a lint-free cloth dipped in a special cleaning agent to remove oil and impurities; a barley paper buffer pad is provided at the contact point between the positioning frame and the rotating worktable to avoid collision damage during assembly.

[0025] This invention utilizes a collaborative design of a "rotational measuring mechanism + laser image projection measuring tool" to achieve lower-segment measurement through reference transfer and upper-segment measurement through laser projection. The specific technical solution is as follows:

[0026] 1. Rotary measuring mechanism

[0027] The rotating measuring mechanism serves as the reference support and lower-section measurement core of the device, used to fix the linear components and establish a vertical measurement reference. Its composition and function are as follows:

[0028] • Positioning Frame: As the main frame, it adopts a four-section cylindrical design for easy disassembly, assembly, and transportation (especially suitable for testing 4m long components). Each section of the cylindrical body is assembled using positioning stops (ensuring coaxiality), positioning pins (limiting circumferential displacement), and fastening bolts (achieving rigid connection). After assembly, the center holes on the upper and lower end faces and the side measurement reference surfaces are precision machined to ensure that the coaxiality between the center holes of the upper and lower sections is ≤0.01mm, and the vertical distance deviation between the measurement reference surface and the axis is ≤0.005mm, providing accuracy assurance for reference transfer. Long, narrow viewing windows (80-120mm wide) around the cylindrical body are used to observe the component installation and measurement status, and the rounded edges prevent scratching the components.

[0029] • Measurement reference planes: There are 8 in total, arranged in two groups on the outer end face of the viewing window. One group is at the same height as the adjusting screws and is staggered circumferentially (4 evenly distributed), used to adjust the coaxiality of the middle section of the linear component and the positioning frame. The distance from the reference plane to the outer cylindrical surface of the middle section is measured with a depth micrometer, and the adjusting screws are adjusted to make the measurement values ​​in the four directions consistent, thus achieving coaxiality between the middle section and the positioning frame. The other group is located on the lower section of the positioning frame (4 evenly distributed), used to measure the distance between the outer cylindrical surface of the lower section and the reference plane, and then calculate the coaxiality deviation between the middle and lower sections.

[0030] • Locking disc: Utilizes a split structure with left and right semi-circular clamps for easy assembly and disassembly from the side (avoiding interference from the upper structure). The inner rubber buffer layer (2-3mm thick) protects the outer surface of the component. Its center hole is coaxial with the center hole of the positioning frame cover plate, allowing it to be closed and secure the upper part of the middle section of the component, ensuring that the middle section's axis coincides with the positioning frame's axis. The lifting eye holes on the locking disc are used for vertical lifting of the component, preventing tilting and deformation during lifting.

[0031] • Adjusting screws: Four screws are evenly distributed in the middle of the positioning frame. The rod has a scale mark with an accuracy of 0.01mm for easy and precise adjustment. The polytetrafluoroethylene hemispherical head at the end has both rigidity and wear resistance, which can avoid damage to the outer surface of the component and reduce frictional resistance during adjustment.

[0032] • Center locating pin and rotary table: The center locating pin connects the bottom pin hole of the positioning frame to the center hole of the rotary table, ensuring that the axis of the positioning frame is coaxial with the rotation center of the rotary table; the rotary table is fixed to the ground platform by adjustable shims, and the levelness can be adjusted to ≤0.02mm / m, providing a stable reference platform for component rotation measurement.

[0033] 2. Laser image projection measurement tool

[0034] The laser image projection measurement tool is the core of the upper section measurement. It uses the laser projection principle to capture the swing deviation of the upper section of the component. Its composition and function are as follows:

[0035] • Laser projection light source and receiving target: The light source emits a linear laser beam, which illuminates the upper surface of the linear component. After being blocked by the component, the laser beam forms a projection, which is captured by the CCD sensor of the receiving target. When the rotating stage drives the component to rotate, if there is a straightness deviation in the upper section, the position of the projection on the sensor will change synchronously. The sensor converts the displacement signal into an electrical signal and transmits it to the control unit.

[0036] • Fixed frame and adapter plate: The adapter plate is used to fix the light source and the receiving target, ensuring that their axes are parallel and coplanar; the fixed frame is connected to the square box through a long hole structure (50-80mm in length). The lubricating coating on the inner wall of the long hole facilitates fine adjustment of the position of the light source and the receiving target, and is compatible with the upper section of linear components of different diameters.

[0037] • Square boxes: Located on both sides of the rotary table, with a height > 4000mm (covering the upper measurement range of the 4m long component), they are fixed on the ground platform together with the rotary table to provide stable support for the laser measurement components. The square boxes on both sides are centered with the rotary table to avoid measurement angle deviation.

[0038] • Control Unit and Laptop: The control unit powers the light source and receiving target, and converts the sensor signal into an RS485 standard signal to enable communication with the laptop. The dedicated software running on the laptop has three main functions: real-time display of measurement values ​​(accuracy 0.001mm), recording of the maximum and minimum values ​​during the measurement process, and automatic generation of inspection reports (including information such as the manufacturing unit, inspection date, and coaxiality deviation at various height positions), which facilitates data traceability and archiving.

[0039] Software development nature: Independent integrated development: Based on open source libraries such as Vue.js, Electron, and Node.js, the business logic interface is developed in-house, without calling third-party commercial APIs / platforms, forming an independent executable software without dependence on third-party commercial platforms.

[0040] Core software development language: JavaScript;

[0041] Development tool: Visual Studio Code;

[0042] Front-end framework: Vue.js;

[0043] Component library: iView;

[0044] runtime environment: Node.js;

[0045] Cross-platform framework: Electron;

[0046] Core dependencies: SerialPort, docxtemplater, PizZip, JSZipUtils, file-saver;

[0047] Node.js module: fs, encoding, child_process;

[0048] Development platform: Windows 10 + VS Code + Node 14;

[0049] Operating platform: Electron 8+ (Chromium 80+);

[0050] Hardware baseline: Intel i3 / ARMv7+, RAM ≥ 512MB;

[0051] Software development logic: Implements the core interactive logic and functions of the software, including device connection detection (determining whether the laser image projection device is successfully connected), measurement data acquisition (real-time acquisition of laser sensor values), data calculation (calculating coaxiality deviation using "(maximum value - minimum value) / 2"), data saving (saving measurement results as a JSON file), serial communication logic, data format conversion, historical data management, Word report generation, etc., which is the "brain" of the software.

[0052] 3. Straightness Inspection Method

[0053] Based on the above-described apparatus, the measurement method of the present invention is implemented according to the following steps to ensure measurement accuracy and efficiency:

[0054] 1. Rotary worktable installation: Place the rotary worktable on the ground platform and adjust it using adjustable shims. Use a level to check the levelness of the end face to ensure it is ≤0.02mm / m. Then tighten the adjustable shims to prevent displacement during measurement.

[0055] 2. Reference positioning: Install a center positioning pin in the center hole of the rotary table, apply a small amount of grease (to reduce assembly resistance), and ensure that the positioning pin fits snugly against the hole wall without gaps.

[0056] 3. Assembly and fixing of positioning frame: Assemble the four sections of cylinder into a positioning frame using positioning stops, positioning pins and bolts. Use an overhead crane to flip it into an upright position (use the top lifting lugs to ensure lifting balance during lifting), and slowly lower it onto the rotating worktable. After positioning it with the center positioning pin, fix the positioning frame to the rotating worktable with bolts. Place barley paper cushioning pads at the contact points between the two to avoid collision damage.

[0057] 4. Installation of linear components: Wipe the outer surface of the linear components with a lint-free cloth dampened with special cleaning agent (to remove oil, iron filings and other impurities to avoid affecting measurement accuracy). Lift the components through the lifting eye hole of the locking plate, align them directly above the positioning frame, lower them slowly and manually adjust them so that the heat sink of the lower section of the component avoids the viewing window of the positioning frame, and the cross wing of the middle section passes through the cross notch on the upper end face of the positioning frame until the middle section is in place in the center hole of the positioning frame cover plate. Close the locking plate and tighten it to ensure that the component is not loose.

[0058] 5. Mid-section reference adjustment: Fix the depth micrometer to the upper section measuring reference surface of the positioning frame, measure the distance from the reference surface to the outer cylindrical surface of the mid-section of the component, and record the measurement values ​​of the four reference surfaces respectively; by adjusting the adjusting screw (refer to the scale on the rod), make the difference between the measurement values ​​in the four directions ≤ 0.005mm, at which point the axis of the mid-section of the component is coaxial with the axis of the positioning frame.

[0059] 6. Lower section straightness measurement: Move the depth micrometer to the measurement reference surface of the lower section of the positioning frame, and measure the distance from the reference surface to the outer cylindrical surface of the lower section of the component in four directions. Calculate the extreme difference of the four measured values ​​in the same cross section. Half of the difference is the coaxiality deviation of the middle and lower sections of the cross section. Select 3-5 cross sections along the length of the lower section for measurement, and take the maximum value as the overall straightness deviation of the lower section.

[0060] 7. Laser Measurement Tool Debugging: Install a fixed frame on the square boxes on both sides of the rotary table. Fix the laser projection light source and the receiving target through the adapter plate. Connect the data cables of the light source, the receiving target and the control unit. Connect the control unit to the laptop. Start the dedicated software and fine-tune the position of the fixed frame (using the elongated hole structure) so that the upper part of the component is in the middle of the laser measurement area. Observe the display of the receiving target. When both the red and green indicator lights are not full, slowly rotate the rotary table one revolution. If the indicator lights are not full (indicating that the upper part swing has not exceeded the range), the position of the fixed frame is qualified.

[0061] 8. Upper section straightness measurement: Set the sampling frequency of the measurement software (10 times / second recommended), rotate the rotary table (speed 1-2 r / min), and the software automatically records the swing deviation of each section of the upper section; after the measurement is completed, the software generates extreme values ​​(maximum value, minimum value) and deviation curves. The maximum deviation value is the coaxiality deviation between the upper and middle sections; combine the deviation values ​​of the upper, middle and lower sections to comprehensively evaluate the overall straightness of the linear component.

[0062] The high-precision straightness inspection device and method of the present invention have the following beneficial effects:

[0063] 1. High measurement accuracy: Through the segmented precision machining of the positioning frame and the coaxial design of the central positioning pin, the accurate transfer of the mid-section reference is achieved, and the measurement accuracy of the lower section can reach 0.005mm; the CCD sensor of the laser projection measuring tool has a resolution of ≤0.001mm, and with the real-time sampling of dedicated software, the measurement accuracy of the upper section can reach 0.002mm, which meets the high-precision inspection requirements of slender stepped shaft components.

[0064] 2. Realistic Scenario Fit: The vertical measurement method is consistent with the actual usage state of the component, avoiding the influence of gravity deformation during horizontal measurement, and the measurement results are more valuable.

[0065] 3. Highly efficient and convenient operation: The segmented design of the positioning frame facilitates disassembly and transportation, and the split structure of the locking plate simplifies the component assembly and disassembly process; the automated sampling and report generation function of the laser measuring tool reduces the workload of manual recording and calculation, and the measurement time of the entire 4m long component can be shortened to less than 30 minutes (the traditional method requires 2-3 hours).

[0066] 4. High adaptability: The scale adjustment of the adjusting screw and the long hole structure of the fixing frame can be adapted to linear parts with diameters of Φ12-Φ30; the height of the square box is >4000mm, which can cover the measurement of parts with a total length ≤4m, without the need to design tooling separately for different specifications of parts.

[0067] 5. Data traceability: Dedicated software can record historical measurement data (including time, operator, and deviation curve) and generate standardized test reports, facilitating quality traceability and process optimization. Attached Figure Description

[0068] Figure 1 This is a schematic diagram of the overall structure of the rotating measuring mechanism;

[0069] Figure 2 This is a sectional view of a rotary measuring mechanism;

[0070] Figure 3 This is a partial view of the locking disc;

[0071] Figure 4 This is a cross-sectional view of the locking disc;

[0072] Figure 5 This is a partial view B of the rotating measuring mechanism;

[0073] Figure 6 This is a schematic diagram of the structure of a laser image projection measurement tool.

[0074] Figure 7 This is a schematic diagram of a laser image projection measuring tool and a rotary measuring mechanism.

[0075] Figure 8 It is the real-time measurement interface of the laser measurement software.

[0076] Figure 9 This is the historical data interface of the laser measurement software.

[0077] Figure 10 This is the interface of the laser measurement software's detection report;

[0078] Wherein: 1-Linear component; 2-Left locking disc; 3-Lifting lug; 4-Right locking disc; 5-Positioning frame; 6-Measuring reference surface; 7-Rotating worktable; 8-Adjusting screw; 9-Center positioning pin; 10-Laser projection receiving target; 11-Adapter plate; 12-Laser projection light source; 13-Fixed frame; 14-Square box. Detailed Implementation

[0079] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0080] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The implementation object is a linear component with a total length of 4m, a middle section diameter of Φ20 (optical axis), a lower section diameter of Φ30 (with 4 heat sinks), and an upper section diameter of Φ12.

[0081] Implementation steps

[0082] 1. Rotary worktable installation: Place the rotary worktable (800mm in diameter) on the ground platform, place four adjustable shims (distributed around the worktable), use a frame level (accuracy 0.02mm / m) to check the levelness of the worktable end face, adjust the shims to make the levelness ≤0.02mm / m, and then tighten the shims to the ground platform with M16 bolts.

[0083] 2. Installation of center locating pin: Apply a small amount of lithium-based grease to the center hole (20mm in diameter) of the rotary table, insert the center locating pin (19.98mm in diameter, with a clearance of 0.02mm), and ensure that the locating pin is vertical and not loose.

[0084] 3. Positioning frame assembly: Take 4 sections of the cylinder (each section is 1m long and has an inner diameter of 50mm). The first section (upper section) and the second section are connected by a positioning stop (stop diameter 45mm, fit clearance 0.01mm). Insert 2 positioning pins (diameter 8mm) and tighten with 4 M12 bolts. Similarly, complete the assembly of the third section (middle section) and the fourth section (lower section). After assembly, use a dial indicator to check the coaxiality of the center holes of the upper and lower end faces to ensure ≤0.01mm.

[0085] 4. Fixing the positioning frame: Use an overhead crane to hook the two lifting lugs on the top of the positioning frame (the lifting lugs can bear a weight of 500kg), flip the positioning frame into an upright position, and slowly lower it onto the rotating worktable so that the pin hole (diameter 20mm) at the bottom of the positioning frame fits into the center positioning pin. Place a barley paper cushioning pad (thickness 0.5mm) at the contact point between the positioning frame and the worktable, and fix the positioning frame to the worktable with 4 M16 bolts.

[0086] 5. Cleaning and hoisting of linear components: Wipe the outer surface of the linear components with a lint-free cloth dampened with isopropyl alcohol cleaner (focusing on cleaning the surface of the middle optical axis and the lower heat sink); pass the hoisting strap through the lifting eye hole of the locking disc, hook it onto the crane hook, and lift the linear component (lifting height 5m). Slowly move it to directly above the positioning frame, manually adjust the component's posture so that the lower heat sink is aligned with the viewing window of the positioning frame, and the middle cross wing passes through the cross notch (notch width 30mm) on the upper end face of the positioning frame until the middle optical axis contacts the center hole (diameter 20.02mm) of the positioning frame cover plate. Close the left and right locking discs and tighten them with 4 M8 bolts to ensure that the component has no axial movement or circumferential rotation.

[0087] 6. Mid-section reference adjustment: Fix a depth micrometer (accuracy 0.001mm) to the four measuring reference surfaces on the upper section of the positioning frame (30mm from the axis). Measure the distance from the reference surfaces to the optical axis of the mid-section and record the values ​​as 9.998mm, 10.002mm, 9.997mm, and 10.003mm. Adjust the four adjusting screws (refer to the scale markings) to adjust the maximum difference (0.006mm) to ≤0.005mm. The final measured values ​​are 9.999mm, 10.000mm, 9.998mm, and 10.001mm, completing the mid-section reference adjustment.

[0088] 7. Lower Section Measurement: Move the depth micrometer to the four measuring reference surfaces of the lower section of the positioning frame (35mm from the axis). Select four sections at 500mm, 1000mm, 1500mm, and 2000mm from the bottom of the lower section. Measure the distance values ​​of each section in four directions. Calculate the extreme differences of each section, which are 0.008mm, 0.007mm, 0.009mm, and 0.006mm, respectively. The corresponding coaxiality deviations are 0.004mm, 0.0035mm, 0.0045mm, and 0.003mm. Take the maximum value of 0.0045mm as the straightness deviation of the lower section.

[0089] 8. Laser tool installation and debugging: Place square boxes (4500mm high, accuracy grade 0) on both sides of the rotary table, with a center distance of 1500mm between the square boxes and the table; install a fixed frame on the top of the square boxes, and fix the laser projection light source (model LS-200, linear laser wavelength 650nm) and the receiving target (model RT-200, CCD resolution 0.001mm) through an adapter plate, with a distance of 3000mm between the light source and the receiving target; connect the light source, the receiving target, and the control unit (model CU-100) with a data cable, and connect the control unit to a laptop (with dedicated software V2.0 installed) via a USB cable; start the software, fine-tune the fixed frame (moving along the long hole) so that the upper part of the component is in the middle of the measurement area, and the red and green lights on the receiving target display are not full; slowly rotate the rotary table one revolution (speed 1r / min), and if the indicator light is not full, the fixed frame position is qualified.

[0090] 9. Upper Section Measurement: Set the sampling frequency to 10 times / second in the software, and measure the heights of 2500mm, 3000mm, 3500mm, and 4000mm (corresponding to the four sections of the upper section); rotate the rotary table (speed 1.5r / min), and the software will automatically record the deviation values ​​of each section. After the measurement is completed, the maximum values ​​of each section will be displayed as 0.003mm, 0.0025mm, 0.0035mm, and 0.0028mm, respectively. Take the maximum value of 0.0035mm as the straightness deviation of the upper section.

[0091] 10. Result Evaluation and Report Generation: The maximum deviation of the lower section is 0.0045mm, the maximum deviation of the upper section is 0.0035mm, and the overall straightness deviation of the linear component is 0.0045mm (meeting the design requirement of ≤0.005mm); click "Generate Report" in the software, fill in the manufacturing unit (XX Machinery Co., Ltd.), inspector (Zhang San), equipment number (ZC-2024-001), export the test report in PDF format, and complete the measurement.

[0092] Precautions

[0093] 1. Before measurement, check the calibration status of the depth micrometer and laser projection light source (calibration cycle is 3 months) to ensure that the tool accuracy is qualified;

[0094] 2. Linear components must be hoisted slowly to avoid collisions with the positioning frame and to prevent deformation of the components or damage to the tooling;

[0095] 3. When using laser projection measurement, strong light sources (such as sunlight or strong flashlights) in the detection area must be turned off to avoid interfering with the signal acquisition of the CCD sensor;

[0096] 4. After measurement, clean the surface impurities of the positioning frame and laser components, loosen the adjusting screws and locking disc, and gently place the linear components to avoid scratching the surface of the components.

[0097] This embodiment fully verifies the feasibility and practicality of the present invention. This technology can achieve high-precision and high-efficiency straightness detection of slender stepped shaft linear components, providing a reliable guarantee for the assembly quality of the components.

[0098] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-precision straightness inspection device for linear components, characterized in that, Including rotary measuring mechanisms and laser image projection measuring tools; The rotating measuring mechanism includes a positioning frame, a locking disc, adjusting screws, lifting lugs, a central positioning pin, and a rotating worktable. The positioning frame is a segmented structure, mainly composed of four cylindrical sections connected by positioning stops, positioning pins, and fastening bolts. A cover plate is provided on the upper cylindrical end face, with its central hole matching the linear component fixing structure. A pin hole is provided in the center of the bottom cylindrical end plate, and the central positioning pin is installed in this pin hole and the central positioning pin hole in the rotating worktable, making the positioning frame coaxial with the rotating worktable. Each of the four cylindrical sections of the positioning frame has a long, narrow viewing window, with eight measuring reference surfaces on the outer end face of each window. The components are arranged in two groups of four, with each group evenly distributed circumferentially and at different heights. One group has the same height as the adjusting screws and is staggered circumferentially, while the other group is located at the lower section of the positioning frame. The locking disc is a split structure with left and right semi-circular clamps, located at the center of the top cover plate of the positioning frame. It is used to fix the upper end of the middle section of the linear component and make it coaxial with the center hole of the cover plate. The locking disc is provided with lifting eye holes. There are four adjusting screws in total, evenly distributed circumferentially at the same height in the middle of the positioning frame. They are used to adjust the distance between the middle section of the linear component and the measurement reference surface. There are two lifting lugs in total, located on the top cover plate of the positioning frame, used to lift the rotating measuring mechanism. The laser image projection measurement tool includes a laser projection light source, a laser projection receiving target, an adapter plate, a fixed frame, a square box, a control unit, and a computer. The adapter plate is mounted on the fixed frame and is used to connect the laser projection light source and the laser projection receiving target. The fixed frame is connected to the square box by bolts, and the connection point is provided with an elongated hole structure to achieve position adjustment. The square box is located on both sides of the rotating measurement mechanism and is fixed to the ground platform together with the rotating worktable. Both the laser projection light source and the laser projection receiving target are connected to the control unit, which is connected to the computer. The control unit supplies power to the laser projection light source and the receiving target and enables RS485 signal networking. The computer is used to display the measured values ​​in real time, record extreme values, and generate test reports.

2. The high-precision straightness inspection device according to claim 1, characterized in that, After the four cylindrical sections of the positioning frame are assembled, the center holes on the upper and lower end faces and the side measuring reference surfaces are precision machined to ensure that the coaxiality error of the center holes on the upper and lower end faces is ≤0.01mm and the vertical distance deviation between the measuring reference surfaces and the axis of the positioning frame is ≤0.005mm.

3. The high-precision straightness inspection device according to claim 1, characterized in that, The width of the elongated viewing window is 80-120mm, and the height is 2 / 3 of the height of a single section of the positioning frame. The edges of the viewing window are provided with a rounded transition structure to prevent scratching of linear components during installation.

4. The high-precision straightness inspection device according to claim 1, characterized in that, The locking disc has a rubber buffer layer on the inner side of the left and right semi-circular clamps. The rubber buffer layer is 2-3mm thick and is used to avoid damage to the outer surface of the middle section of the linear component when locking.

5. The high-precision straightness inspection device according to claim 1, characterized in that, The adjusting screw has a scale marking on its shank with a scale accuracy of 0.01 mm, and a hemispherical head at the end of the screw, which is made of polytetrafluoroethylene.

6. The high-precision straightness inspection device according to claim 1, characterized in that, The elongated hole structure of the fixed frame has a length of 50-80mm and a width that is 2-3mm larger than the diameter of the connecting bolt. The inner wall of the elongated hole is provided with a lubricating coating to facilitate the adjustment of the fixed frame position.

7. A method for high-precision straightness inspection of linear components using the apparatus described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Fix the rotary table to the ground platform using adjustable shims to complete the installation of the rotary table; S2: Install a center positioning pin in the center hole of the rotary table; S3: Use an overhead crane to flip the positioning frame assembly to an upright position, lift the positioning frame assembly and position it with the rotary table through the central positioning pin, and fix it with fasteners; S4: Lift the linear component through the lifting eye hole of the locking plate, lift it to the top of the positioning frame, slowly lower it and assist the linear component's cross wings to pass through the cross notch on the upper surface of the positioning frame, so that the middle section of the linear component is in place on the upper surface of the positioning frame, and close the locking plate to fix the linear component. S5: Using the notch on the side wall of the positioning frame, the measuring reference surface, and the adjusting screw, adjust the middle section of the linear component with a depth micrometer to make the outer cylindrical surface of the middle section equidistant from the measuring reference surface; S6: Using the measuring reference surface of the lower section of the positioning frame and a depth micrometer, measure the distance between the outer cylindrical surface of the lower section of the linear component and the reference surface, and calculate the coaxiality deviation between the middle and lower sections of the linear component; S7: Install the fixed frame, adapter plate, laser projection light source and laser projection receiving target of the laser image projection measuring tool on the square boxes on both sides of the rotary table. Connect the laser projection light source, receiving target and control unit through data cable. Connect the control unit to the computer. Start the special software to check the alignment and range compatibility of the laser projection light source and receiving target. S8: Rotate the rotary table, and the dedicated software will automatically record the swing deviation of the upper section of the linear component. This deviation is the coaxiality deviation of the middle and upper sections of the linear component, thus completing the straightness check.

8. The high-precision straightness inspection method according to claim 7, characterized in that, In step S1, after the rotating worktable is fixed, its end face level is checked by a level to ensure that the levelness is ≤0.02mm / m.

9. The high-precision straightness inspection method according to claim 7, characterized in that, In step S7, the alignment check method between the laser projection light source and the receiving target is as follows: finely adjust the position of the fixed frame so that the upper section of the linear component is in the middle of the measurement area, and the red and green indicator lights in the middle area of ​​the receiving target position display are not full; slowly rotate the rotating table one revolution. If the indicator lights are not full, the alignment is qualified.

10. The high-precision straightness inspection method according to claim 7, characterized in that, In step S4, before lifting the linear component, wipe the outer surface of the linear component with a lint-free cloth dipped in special cleaning agent to remove oil and impurities; the contact area between the positioning frame and the rotating worktable is equipped with a barley paper buffer pad to avoid collision damage during assembly.

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