A calibration fixture and calibration method for a dual-needle profilometer probe.

Abstract

This invention provides a calibration fixture and method for a dual-needle profilometer stylus, comprising: a mounting base with a second through hole facing forward and backward; an adjusting base slidably fitted to the front end of the mounting base along the Z-axis, the adjusting base having a first through hole facing the second through hole; a micrometer screw gauge vertically fixed to the mounting base, capable of driving the adjusting base to move up and down along the Z-axis; a ball-end assembly including two tightening bolts threaded along the X-axis to both sides of the adjusting base and coaxially arranged, the ends of the two tightening bolts forming a tightening area; a ring gauge vertically mounted on the mounting base, the center of the ring gauge having a through hole forming a first reference part, accommodating an image sensor; and a sphere located within the tightening area, serving as a second reference part, accommodating an image sensor. This invention's dual-needle profilometer stylus calibration fixture and method improves the reliability of the detection results and provides reliable support for high-precision, high-efficiency calibration of the dual-needle profilometer stylus.

Description

Technical Field

[0001] This invention relates to a testing instrument, and more particularly to a calibration fixture and calibration method for a dual-needle profilometer. Background Technology

[0002] The dual-needle profilometer, a high-precision surface profile measuring instrument, is widely used in mechanical manufacturing, optical processing, and other fields. Its measurement accuracy directly depends on the geometric parameters of the stylus and the accuracy of its installation position. However, current technology lacks efficient calibration tools specifically designed for dual-needle profilometer styluses. Traditional calibration methods often suffer from complex operation, low calibration accuracy, and long processing times, failing to meet the demands of modern industry for rapid and accurate calibration of precision measuring instruments. Therefore, developing a dual-needle profilometer stylus calibration fixture that is simple in structure, easy to adjust, and offers high calibration accuracy is of significant practical importance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a compact, easy-to-adjust, and highly accurate dual-needle profilometer stylus calibration fixture and calibration method.

[0004] This invention provides a calibration fixture for a dual-needle profilometer, comprising:

[0005] The mounting base has a second through hole 110 facing back and forth.

[0006] Adjustment seat 5 is slidably fitted at the front end of the mounting seat along the Z-axis direction, and the adjustment seat has a first through hole 20 extending toward the second through hole;

[0007] The micrometer 9 is vertically fixed on the mounting base. The measuring axis of the micrometer 9 is connected to the adjusting base 5 and can drive the adjusting base 5 to move up and down along the Z-axis.

[0008] The ball-mounted assembly includes two tightening bolts threaded along the X-axis to both sides of the adjusting seat 5 and coaxially arranged. A tightening area is formed between the ends of the two tightening bolts. The tightening area is located within the first through hole 50 and its width and horizontal position are adjustable.

[0009] A ring gauge 21 is vertically mounted on the mounting base. The center of the ring gauge 21 has a through hole and forms a first reference part 210. All or part of the first reference part 210 is exposed and can be detected by an image instrument.

[0010] The sphere 22 is located within the tightening area and is tightened and fixed by the two tightening bolts. The sphere 22 serves as a second reference part, which is located inside the first reference part 210 and can be detected by the image sensor.

[0011] Furthermore, the first reference portion is exposed inside the first through hole 50 and the second through hole 110 and / or outside the adjusting seat 5.

[0012] Furthermore, the first through hole 50 is strip-shaped and its length direction is parallel to the moving direction of the adjusting seat 5, and the distance from the ball 22 to the upper and lower ends of the first through hole 50 is greater than the height of the probe of the profilometer.

[0013] Furthermore, the upper or lower end of the first through hole 50 is located outside the first reference portion and / or at least one side edge of the adjustment seat 5 is located inside the first reference portion.

[0014] Furthermore, the mounting base includes a back plate 11 parallel to the ring gauge 21, and the back plate 11 has a second through hole 110. The adjusting base 5, the ring gauge 21 and the back plate 11 are arranged sequentially from front to back.

[0015] Furthermore, the adjusting seat 5 has symmetrically provided threaded holes on both sides that connect to the first through hole 50. The axis of the threaded hole is parallel to the horizontal plane and perpendicular to the axis of the ring gauge 21. The tightening bolt is threaded into the threaded hole and can move along the X-axis.

[0016] Furthermore, the mounting base includes a back plate 11, an upper clamping block 12 mounted on the upper end of the back plate 11, and a lower clamping block disposed on the lower end of the back plate 11. A ring gauge mounting area is formed between the upper clamping block 12 and the lower clamping block, which can clamp the outer wall of the ring gauge 21 and radially limit the ring gauge 21. The front end of the ring gauge mounting area is provided with a plurality of pressure blocks that can be adjusted back and forth and used to axially press the ring gauge.

[0017] Furthermore, the lower clamping block includes a lower clamping block seat 14 fixed to the lower end of the back plate 11, and two lower clamping block bodies 15 are mounted on the upper surface of the lower clamping block seat 14, with the distance between the two lower clamping block bodies 15 being adjustable.

[0018] Furthermore, the upper surface of the lower clamping block seat 14 is provided with a strip groove 140 along the X direction, and the bottom surface of the lower clamping block body 15 is provided with a protrusion 151 that can be inserted into the strip groove 140 and slide left and right. The bottom surface of the strip groove 140 is provided with a strip-shaped mounting hole. After the bolt passes through the mounting hole from bottom to top, it is connected to the lower clamping block body 15 and the lower clamping block body 15 is fixed.

[0019] Furthermore, the front ends of the upper clamping block and the lower clamping block are respectively provided with an upper connecting plate 3 and a lower connecting plate 4, and the front ends of the upper connecting plate 3 and the lower connecting plate 4 are provided with sliding grooves along the Z-axis; sliding seats are slidably installed in the two sliding grooves respectively, the adjusting seat 5 is fixed between the two sliding seats, and the measuring shaft of the micrometer 9 is connected to the upper sliding seat; the pressure block is installed on the upper connecting plate 3 and / or the lower connecting plate 4.

[0020] Furthermore, the tightening bolt includes a fixed bolt 62 and a movable bolt 61. The ends of the fixed bolt 62 and the movable bolt 61 are provided with operating parts for adjusting the horizontal position. The movable bolt 61 includes a movable bolt body 611 and a pressure column 612. The head of the movable bolt body 611 is provided with a guide hole 6110. The guide hole 6110 is coaxial with the movable bolt body 611. The pressure column 612 is sleeved in the guide hole 6110 and can realize axial movement and radial rotation. The guide hole 6110 is provided with an elastic component that makes the pressure column 612 have an outward movement tendency to press the ball 22.

[0021] Meanwhile, the present invention also provides a calibration method for a dual-needle profilometer probe, which includes the following steps:

[0022] S1. Tooling calibration:

[0023] S11. Use an image acquisition device to acquire images of the inner wall arc of the ring gauge and the outer wall arc of the sphere respectively. Use software to fit and obtain the fitted circles of the ring gauge and the sphere respectively, and calculate their center positions.

[0024] S12. By operating the tightening bolt and the micrometer screw, adjust the spatial position of the sphere so that the positional deviation between the center of the sphere's fitting circle and the center of the ring gauge's fitting circle in the X and Z axis directions reaches the allowable threshold, forming a calibration fixture with the sphere's center and the ring gauge's center coaxial, thus completing the self-calibration of the calibration fixture.

[0025] S2. Calibrate the profilometer probe:

[0026] S21. Install the calibrated fixture onto the worktable and calibrate the dual-needle profilometer using at least one of the following methods;

[0027] a. Control a single probe to scan the arc of the sphere, fit the diameter and compare it with the nominal diameter of the sphere to calculate the probe accuracy error;

[0028] b. Control the two probes to scan the upper and lower arcs of the sphere respectively, fit the diameter and compare the difference to calculate the measurement accuracy error of the two probes;

[0029] c. Move the ball vertically using a micrometer screw gauge and record the movement distance Z1. Scan the arc of the steel ball before and after the movement using a double probe and fit the center of the circle. Calculate the distance difference Z2 between the fitted centers before and after the movement. Compare Z1 and Z2 and calculate the measurement accuracy error.

[0030] S3. Based on the error results of step S2, calibrate the probe of the dual-needle profilometer according to the comparison results so that the values ​​measured by the two are consistent.

[0031] The present invention relates to a calibration fixture and method for a dual-needle profilometer stylus. It employs dual reference units for collaborative calibration, which improves the reliability of the test results. At the same time, it simplifies the operation through intuitive adjustment components and integrated processes, solving the problems of complex operation, inconvenient replacement, and unstable calibration accuracy in traditional calibration tools. This provides reliable support for high-precision and high-efficiency calibration of dual-needle profilometer styluses. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the dual-needle profilometer probe calibration fixture of the present invention;

[0033] Figure 2 This is a schematic diagram of the dual-needle profilometer probe calibration fixture from another angle.

[0034] Figure 3 This is a longitudinal sectional view of the probe calibration fixture for the dual-needle profilometer of the present invention;

[0035] Figure 4 This is a half-sectional view of the probe calibration fixture for the dual-needle profilometer of the present invention;

[0036] Figure 5 This is a cross-sectional view of the probe calibration fixture for the dual-needle profilometer of the present invention.

[0037] Figure 6 for Figure 5 Enlarged view of section A in the middle;

[0038] Figure 7 This is another planar sectional view of the calibration fixture for the dual-needle profilometer of the present invention;

[0039] Figure 8 This is an exploded structural diagram of the probe calibration fixture for the dual-needle profilometer of the present invention;

[0040] Figure 9 This is a schematic diagram of the installation of the adjustment seat of the dual-needle profilometer probe calibration fixture of the present invention;

[0041] Figure 10 This is a schematic diagram of the installation of the upper and lower clamping blocks of the dual-needle profilometer probe calibration fixture of the present invention.

[0042] Figure 11This is a schematic diagram of the upper connecting plate of the dual-needle profilometer probe calibration fixture of the present invention;

[0043] Figure 12 This is a schematic diagram of the lower connecting plate of the dual-needle profilometer probe calibration fixture of the present invention;

[0044] Figure 13 This is a schematic diagram of the installation of the tightening bolt of the probe calibration fixture for the dual-needle profilometer of the present invention.

[0045] In the diagram: 3. Upper connecting plate, 4. Lower connecting plate, 5. Adjusting seat, 8. Micrometer mounting seat, 9. Micrometer, 11. Back plate, 12. Upper clamping block, 13. Upper clamping block mounting seat, 14. Lower clamping block seat, 15. Lower clamping block body, 21. Ring gauge, 22. Sphere, 30. First sliding groove, 31. First pressure block, 40. Second sliding groove, 41. Second pressure block, 50. First through hole, 61. Moving bolt, 62. Fixed bolt, 71. Upper sliding seat, 72. Lower sliding seat, 110. Second through hole, 140. Strip groove, 151. Protrusion, 210. First reference part, 611. Moving bolt body, 612. Pressure column, 6112. Knob, 6121. Concave hole, 6110. Guide hole, 711. First dovetail protrusion, 721. Second dovetail protrusion. Detailed Implementation

[0046] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0047] See Figures 1-13 The present invention provides a calibration fixture for a dual-needle profilometer, which is used to quickly calibrate a dual-needle profilometer. It includes a mounting base, an adjusting base 5, a micrometer screw gauge 9, a top ball assembly, a ring gauge 21, and a ball 22.

[0048] The mounting base, serving as the mounting carrier, has a cuboid structure. The adjusting seat 5 slides along the Z-axis at the front end of the mounting base, meaning the adjusting seat 5 can move vertically (perpendicular to the horizontal plane). A first through hole 50 is formed in the adjusting seat 5, with the first through hole 50 facing forward and backward. The first through hole 50 has multiple functions: first, it serves as a receiving space for the sphere 22; second, it allows the probe of the dual-needle profilometer to be inserted for calibration; and finally, it allows light to pass through, enabling contour detection of the sphere 22 and centering.

[0049] The micrometer 9 is vertically fixed on the mounting base. In this embodiment, the micrometer 9 is installed on the upper end of the adjusting base 5, and its axis is perpendicular to the horizontal plane, that is, parallel to the sliding direction of the adjusting base 5. The measuring axis of the micrometer 9 is connected to the adjusting base 5, which can drive the adjusting base 5 to move up and down along the Z-axis, so as to realize the precise movement of the adjusting base 5 in the Z-axis direction and adjust the vertical height of the ball 22. The micrometer 9 is a micrometer with an accuracy of 0.01mm, which can control the high-precision positioning and movement of the adjusting base 5 (with ball 22) in the vertical direction.

[0050] The ball-mounted assembly includes two tightening bolts threaded to both sides of the adjusting seat 5. The two tightening bolts are coaxially arranged, and their axes are parallel to the X-axis. A tightening area is formed between the ends of the two tightening bolts. Specifically, one end of the opposite face of the tightening bolt is located in the first hole. This end has a circular concave structure, which can increase the contact area with the ball 22 and achieve clamping and fixing of the ball 22. A tightening area is formed between the two concave structures, and this tightening area is located in the first through hole 50. The position and width of the tightening area can be adjusted by the horizontal movement of the two tightening bolts.

[0051] The ring gauge 21 has an overall circular structure and is vertically mounted on the mounting base. Its axis is set at the front and back. A circular hole runs through the center of the ring gauge 21, which forms a first reference part 210. All or part of the first reference part 210 is exposed and can be detected by the image instrument. Partial exposure means that one or more sections of the circular arc edge of the circular hole are exposed and can be detected by the image instrument.

[0052] The sphere 22, which is a steel ball in this embodiment, is located in the tightening area and is tightened and fixed by two tightening bolts. The sphere 22 serves as the second reference part, which is located inside the first reference part 210 (inner side in the radial direction). The radial direction is the up, down, left, and right direction when viewed from front to back, and it can be detected by the image sensor.

[0053] The aforementioned first through hole accommodates the sphere 22, providing installation space for the sphere 22 and ensuring that it is stably clamped by the tightening bolt; as a probe channel, it allows the probe of the dual-needle profilometer to be inserted into and contact the surface of the sphere for calibration; forming an optical path, the inner wall of the through hole is smooth and unobstructed, allowing light to pass through, and working with the image instrument to perform centering detection of the sphere profile. This design achieves multiple functions through a single structure, reduces redundant components, and simplifies the overall structure.

[0054] The ring gauge adopts a circular ring structure, with a central circular hole forming the first reference part 210, and part of its arc edge is exposed to adapt to the image instrument detection; the sphere 22 serves as the second reference part, and is fixed to the inner side (inner side in the radial direction) of the first reference part by a tightening bolt, and the axes of the two are aligned front and back; this allows the image instrument to acquire the position parameters of the two reference parts simultaneously through a single shot, providing a dual reference for calibration and improving the reliability of the calibration results.

[0055] The ball 22 can move horizontally and vertically. It uses a micrometer to drive the adjusting seat to move along the Z-axis with an accuracy of 0.01mm, which can achieve high-precision positioning of the adjusting seat (and ball 22) in the vertical direction. The micrometer's micro-tube design allows the operator to make fine adjustments by rotation. Combined with the guide rail slider structure of the adjusting seat and the mounting seat, it ensures smooth and uninterrupted movement, meeting the calibration requirements of the measuring needle in the vertical direction. At the same time, the two tightening bolts of the ball assembly are coaxially set, and the ends adopt a circular concave structure, which effectively increases the contact area and avoids the ball 22 offset caused by point contact. By tightening the bolts on both sides respectively, the horizontal position and width of the tightening area can be precisely adjusted to achieve coaxiality calibration between the center of the ball 22 and the center of the ring gauge hole, and different specifications of ball 22 can be replaced.

[0056] The first reference part (circular hole of the ring gauge) serves as a static reference, and the second reference part (sphere 22) serves as a dynamic reference. The position is adjustable through the adjusting seat and the tightening bolt. After the image instrument detects the coordinates of the sphere center, it can compare them with the coordinates of the center of the circular hole to calculate the relative positional deviation between the two, and then infer the geometric parameter error of the needle. This application adopts dual references to form a calibration system with a static reference and a dynamically adjustable one, which solves the problem that the reference error cannot be quantified in the traditional single reference calibration.

[0057] This application employs dual reference units for collaborative calibration, which improves the reliability of the results. At the same time, it simplifies the operation through intuitive adjustment components and integrated processes, solving the pain points of traditional calibration tools such as loose structure, rough adjustment, and single function. It provides reliable support for high-precision and high-efficiency calibration of the probe of the dual-needle profilometer.

[0058] In this embodiment, a second through hole 110 is also provided on the mounting base. The second through hole 110 faces the first through hole 50, i.e., it faces forward and backward. The first reference part is exposed on the inner side (inner side in the radial direction) of the first through hole 50 and the second through hole 110, or on the outer side (outer side in the radial direction) of the adjusting base 5, which allows the image instrument to detect the arc-shaped surface. In this embodiment, the second through hole 110 is also strip-shaped, and its length direction is perpendicular to the horizontal plane, i.e., parallel to the moving direction of the adjusting base. The length (height) of the second through hole is greater than the diameter of the first reference part 210. Specifically, the upper and lower ends of the second through hole are located on the outer side of the first reference part 210. Therefore, a part (arc-shaped edge) of the first reference part 210 is located inside the second through hole, forming a partial exposure. On the one hand, this can improve the compactness of the overall structure and effectively control the overall volume. On the other hand, it makes it easier for the image instrument to directly observe the arc-shaped edge of the first reference part 210 from the front or the rear, improving alignment efficiency and imaging clarity, while avoiding visual errors caused by external obstruction.

[0059] In this application, two screw holes are symmetrically opened on both sides of the adjusting seat 5. The inner side of the screw holes is connected to the first through hole 50. The two screw holes are coaxial, and their axes are parallel to the horizontal plane and perpendicular to the axis of the ring gauge 21. The tightening bolt is threaded in the screw hole and moves along the X-axis, thereby adjusting the horizontal position and width of the tightening area.

[0060] In this embodiment, the tightening bolt includes a fixed bolt 62 and a movable bolt 61. Both the fixed bolt 62 and the movable bolt 61 have operating mechanisms at their ends for adjusting bolt rotation, thereby achieving horizontal adjustment. Preferably, the fixed bolt has a slotted groove or a cross-shaped groove at its end for precise horizontal adjustment by turning it with a tool. The movable bolt has a knob 6112 at its end, which can be manually rotated for quick tightening. Specifically, the movable bolt 61 includes a movable bolt body 611 and a pressure post 61. 2. The head of the movable bolt body 611 has a guide hole 6110, which is coaxial with the movable bolt body 611. The pressure column 612 is sleeved in the guide hole 6110, enabling axial movement and radial (circumferential) rotation. Simultaneously, an elastic component (not shown in the figure) is provided within the guide hole 6110, which gives the pressure column 612 an outward tendency to press against the ball 22. The end of the pressure column 612 is an inwardly recessed hole 6121, forming a clamping part for fitting against the ball and achieving clamping. When fine-tuning the ball 22, only the set bolt needs to be adjusted, while the pressure column, under the action of the elastic component, remains in contact with the surface of the ball, preventing the ball from loosening. Through the above structural design, stable clamping and precise adjustment of the ball 22 can be achieved, while improving operational convenience and structural reliability.

[0061] To facilitate probe calibration, in this embodiment, the first through hole 50 is strip-shaped, with its length parallel to the moving direction of the adjusting seat 5, i.e., vertically positioned. The distance from the ball 22 to the upper and lower ends of the first through hole 50 is greater than the total height of the profilometer probe. This ensures that the probe can be smoothly inserted into the first through hole 50 to detect the contour of the ball 22. The vertical strip structure of the first through hole is suitable for probe movement paths, allows for large pre-reserved spacing for posture adjustment, and solves the problem of probe insertion convenience. It is compatible with multiple probe specifications, expanding the applicability of the tooling; it improves safety and stability, and reduces gears in the width direction, effectively controlling the overall structural volume.

[0062] The upper or lower end of the first through hole 50 is located outside the first reference portion 210, and at least one edge of the adjusting seat 5 is located inside the first reference portion 210 (inner side in the radial direction). In this embodiment, both the upper and lower ends of the first through hole 50 are located outside the first reference portion 210. At the same time, the width of the adjusting seat 5 is smaller than the diameter of the first reference portion 210, and the portions on both sides of the first reference portion 210 are exposed outside the adjusting seat 5. The upper and lower ends of the first through hole 50 both exceed the range of the first reference portion 210 (circular hole) of the ring gauge 21, so that the upper and lower arc-shaped edges of the circular hole are completely exposed (not blocked by the adjusting seat). Combined with the fact that the width of the adjusting seat 5 is smaller than the diameter of the reference portion, notches are formed on its left and right sides, so that the left and right arc-shaped edges of the circular hole are exposed. Finally, the upper, lower, left, and right arc-shaped surfaces of the first reference portion 210 are all exposed, which increases the exposed contour length, thereby improving the center positioning accuracy and detection repeatability, and providing more complete contour data support for the image instrument.

[0063] In this embodiment, the mounting base includes a back plate 11 parallel to the ring gauge 21, and a second through hole 110 is formed on the back plate 11. The adjusting seat 5, the ring gauge 21 and the back plate 11 are arranged sequentially from front to back.

[0064] Specifically, the mounting base includes a back plate 11, an upper clamping block 12 mounted on the upper end of the back plate 11, and a lower clamping block located at the lower end of the back plate 11. The upper clamping block 12 and the lower clamping block form a V-shaped structure, creating a ring gauge mounting area between them. This area clamps the outer wall of the ring gauge 21, thereby radially limiting the ring gauge 21. Simultaneously, multiple pressure blocks are located at the front end of the ring gauge mounting area. These pressure blocks are adjustable forward and backward, used to axially press the ring gauge 21 backward. This ensures stable clamping and rapid positioning of the ring gauge 21, preventing displacement or vibration during testing. It provides a stable testing reference for the ring gauge 21, ensuring the accuracy and repeatability of measurement data. In this embodiment, the upper clamping block 12 has triangular protrusions at both ends, forming two positioning protrusions for contacting the upper end of the ring gauge 21 to achieve positioning. The lower clamping block includes a lower clamping block seat 14 fixed to the lower end of the back plate 11. Two lower clamping block bodies 15 are mounted on the upper surface of the lower clamping block seat 14, and the distance between the two lower clamping block bodies 15 is adjustable. Specifically, a strip groove 140 is provided along the X direction on the upper surface of the lower clamping block seat 14, and a protrusion 151 is provided on the bottom surface of the lower clamping block body 15, which can be engaged in the strip groove 140 to achieve left and right sliding. A strip-shaped mounting hole is provided on the bottom surface of the strip groove 140. The bolt passes through the mounting hole from bottom to top and connects to the lower clamping block body 15, thereby fixing the lower clamping block body 15. It can adjust the relative position of the two lower clamping block bodies 15 along the X direction according to the actual detection requirements, or replace the lower clamping block bodies 15 of different specifications (heights) to adapt to the installation of ring gauges of different diameters, improve the versatility of the device, and can adjust the height of the ring gauge 21 to meet the detection requirements of different specifications of ring gauges 21. Its structure is compact, easy to assemble, and has low manufacturing cost.

[0065] To facilitate the loading and unloading of the upper clamping block 12, in this embodiment, an upper clamping block mounting seat 13 is fixed at the upper end of the back plate 11. The upper clamping block 12 is fixed to the lower end of the upper clamping block mounting seat 13 by bolts. The bolts pass through the upper clamping block mounting seat 13 from top to bottom and are connected to the upper clamping block 12, so as to realize the quick loading and unloading of the upper clamping block 12.

[0066] The upper clamping block and the lower clamping block are respectively provided with an upper connecting plate 3 and a lower connecting plate 4 at their front ends. Slide grooves are provided along the Z-axis at the front ends of the upper connecting plate 3 and the lower connecting plate 4. Slide seats are slidably installed in the two slide grooves respectively. The adjusting seat 5 is fixed between the two slide seats. The measuring shaft of the micrometer 9 is connected to the upper slide seat. The pressure block is installed on the upper connecting plate 3 and the lower connecting plate 4.

[0067] Specifically, the upper connecting plate 3 is installed at the front end of the upper clamping block mounting base 13. A first sliding groove 30 is vertically opened at the front end of the upper connecting plate 3. A notch is provided on both sides of the lower end of the upper connecting plate 3. A first pressing block 31 is provided in the notch. The first pressing block 31 is fixed to the notch by screws. Specifically, a strip-shaped mounting hole is opened on the first pressing block 31. Its length direction is parallel to the axis of the ring gauge 21. After the bolt passes through the mounting hole, it is fixedly connected to the upper connecting plate 3 to realize the fixation and fine adjustment of the first pressing block 31. The first sliding groove 30 is a dovetail groove. An upper sliding seat 71 is slidably fitted in the first sliding groove 30. The rear end of the upper sliding seat 71 is provided with a first dovetail protrusion 711 that matches the first sliding groove 30. The upper sliding seat 71 is slidably connected to the first sliding groove 30 through the first dovetail protrusion 711. The measuring shaft of the micrometer 9 is connected to the upper sliding seat 71.

[0068] The lower connecting plate 4 is installed at the front end of the lower clamping block. A second sliding groove 40 is vertically opened at the front end of the lower connecting plate 4. A notch is provided on both sides of the upper end of the lower connecting plate 4. A second pressure block 41 is provided in the notch. The second pressure block 41 is fixed to the notch by screws. Specifically, a strip-shaped mounting hole is opened on the second pressure block 41. Its length direction is parallel to the axis of the ring gauge 21. After the bolt passes through the mounting hole, it is fixedly connected to the lower connecting plate 4 to realize the fixation and fine adjustment of the second pressure block 41. The second sliding groove 40 is a dovetail groove. A lower sliding seat 72 is slidably fitted in the second sliding groove 40. The rear end of the lower sliding seat 72 is provided with a second dovetail protrusion 721 that matches the second sliding groove 40. The lower sliding seat 72 is slidably connected to the second sliding groove 40 through the second dovetail protrusion 721.

[0069] When the ring gauge 21 needs to be replaced, loosen the pressure block on the upper and lower connecting plates, the upper clamping block on the upper clamping block mounting base, and the lower clamping block body on the lower clamping block base. Then, remove the lower clamping block body on one side and pull the ring gauge 21 along with the upper clamping block out from that side. After replacing the ring gauge 21 with the required size, insert the ring gauge 21 along with the upper clamping block, then put the lower clamping block body in. Finally, adjust the radial position of the ring gauge 21, lock the lower clamping block body and the upper clamping block in sequence, and finally, lock the pressure block and press the ring gauge 21.

[0070] To facilitate the installation of the micrometer 9, a micrometer mounting base 8 is installed at the upper front end of the upper connecting plate for installing the micrometer 9.

[0071] Meanwhile, the present invention also provides a calibration method for a dual-needle profilometer probe, which includes the following steps:

[0072] S1. Fixture calibration is used to establish a reference. Its purpose is to adjust the ring gauge 21 and the ball 22 of the calibration fixture to an ideal coaxial state, so as to provide a known and accurate geometric reference for subsequent profilometer calibration.

[0073] S11. Use an image acquisition device to acquire images of the inner wall arc of the ring gauge 21 and the outer wall arc of the sphere 22 respectively. Use software to fit and obtain the fitted circles of the ring gauge and the sphere respectively, and calculate their center positions.

[0074] It is used to obtain the initial center position. The calibration fixture is placed under the observation platform of the image instrument. Through the high-magnification lens of the image instrument, multi-angle images of the inner arc of the ring gauge 21 and the outer arc of the sphere 22 are acquired. Due to the obstruction of the fixture structure, only partial arc images are acquired. The acquired images are transmitted to computer processing software. The software uses arc fitting algorithms such as the least squares method to fit the partial inner arc of the ring gauge 21 and the partial outer arc of the sphere 22, respectively, to obtain high-precision ring gauge fitting circles and sphere fitting circles, and automatically calculates the center coordinates of these two fitting circles.

[0075] S12. By operating the tightening bolt and the micrometer screw 9, adjust the spatial position of the sphere 22 so that the positional deviation between the center of the sphere fitting circle and the center of the ring gauge fitting circle in the X and Z axis directions reaches the allowable threshold, forming a calibration fixture with the sphere center and the ring center coaxial, and completing the self-calibration of the calibration fixture.

[0076] The operator fine-tunes the spatial position of sphere 22 based on the center coordinate deviation displayed in the software; this includes horizontal and vertical alignment. For horizontal alignment, the two horizontal tightening bolts are loosened or tightened to change their clamping force and position on sphere 22, thereby fine-tuning the sphere's position in the horizontal plane and reducing the difference in horizontal distance between the center of sphere 22 and the center of ring gauge 21. For Z-axis adjustment, the micrometer is adjusted to drive the adjusting seat and the entire sphere to move vertically up and down, ensuring that the equatorial plane of sphere 22 is approximately aligned with the specific measurement section of ring gauge 21, preparing for subsequent measurements.

[0077] Repeat steps S11 and S12 for measurement and adjustment until the positional deviations of the center of the sphere fitting circle and the center of the ring gauge fitting circle in the X and Z axes are both less than the preset allowable thresholds. At this point, the calibration fixture is calibrated, forming a precise reference where the center of the sphere and the center of the ring gauge are coaxial.

[0078] S2. Calibrate the profilometer stylus. In this stage, the profilometer stylus of the dual-needle profilometer is calibrated using the calibrated fixture to calibrate multiple performance indicators.

[0079] S21. Install the calibrated fixture onto the worktable and calibrate the dual-needle profilometer using at least one of the following methods;

[0080] a. Control the single probe to scan the arc of the sphere, fit the diameter and compare it with the nominal diameter of sphere 22 to calculate the probe accuracy error;

[0081] It is used to calibrate the absolute accuracy of a single probe. It controls one of the upper or lower probes to perform a contact scan near the maximum equator of the sphere 22, tracing the outer arc profile of the sphere. The software of the dual-needle profilometer performs arc fitting on the collected profile data points, calculates the diameter of the fitted circle, compares the diameter of the fitted circle with the standard nominal diameter of the sphere 22, calculates the difference between the two according to the formula, and then calculates the dimensional measurement accuracy error of the probe.

[0082] b. Control the two probes to scan the upper and lower arcs of the sphere 22 respectively, fit the diameter and compare the difference to calculate the measurement accuracy error of the two probes.

[0083] This is a consistency calibration for dual probes. The upper probe is controlled to trace an arc at the top of the sphere 22, while the lower probe is controlled to trace another arc at the bottom of the sphere. The profilometer software independently fits the data collected by the two probes to obtain the diameters of the two fitted circles. The difference between the two diameters is calculated. This difference directly reflects the measurement consistency error between the upper and lower probes. If the difference exceeds the allowable range, it indicates that there is a deviation between the two probes, and calibration is required to synchronize them.

[0084] c. Move the ball 22 vertically using the micrometer screw gauge and record the moving distance Z1 of the micrometer screw gauge. Scan the arc of the steel ball before and after the movement using the double probe and fit the center of the circle. Calculate the distance difference Z2 between the fitted centers before and after the movement. Compare Z1 and Z2 and calculate the measurement accuracy error.

[0085] It involves Z-axis positioning accuracy calibration, specifically including:

[0086] 1. Initial position measurement: Control the upper or lower needle to trace an arc on the sphere, and obtain and record the initial Z-axis coordinate of the sphere's center at this time through software fitting.

[0087] 2. Apply a standard displacement and precisely drive the ball 22 to move vertically a known distance in the Z-axis direction by operating the micrometer 9 on the tooling. Record the reading of the micrometer 9 as the standard movement distance Z1.

[0088] 3. End position measurement: Using the same probe again, trace an arc at the new position of the moved sphere, and obtain and record the new Z-axis coordinates of the sphere's center by fitting the data with software.

[0089] 4. Error calculation: Calculate the displacement Z2 measured by the profilometer. The displacement value Z2 is the new Z-axis coordinate of the sphere center minus the initial Z-axis coordinate. Compare Z2 with the standard displacement Z1. According to the formula Z-axis error = Z2 - Z1, calculate the positioning and measurement accuracy error of the dual-needle profilometer in the Z-axis direction.

[0090] S3. Based on the error results of step S2, calibrate the probe of the dual-needle profilometer according to the comparison results so that the values ​​measured by the two are consistent.

[0091] It is used for error correction and system calibration. Based on the error results obtained in step S2 in one or more ways, including single needle accuracy error, double needle consistency error, and Z-axis positioning error, the corresponding error values ​​are input into the software calibration module of the double needle profilometer, and the calibration command is executed. The software system will compensate and correct the measurement data according to these error values, or guide the operator to make necessary mechanical adjustments to the probe. Its ultimate goal is to make the measurement values ​​of the profilometer consistent with the reference values ​​calibrated by the tooling or the standard displacement values ​​provided by the micrometer 9 after calibration, thereby ensuring the overall measurement accuracy of the double needle profilometer.

[0092] This application establishes absolute and relative references by setting up a ring gauge and a sphere. The steel sphere serves as the absolute dimensional reference; it is a standard with a known precise diameter. When the probe traces its contour, the arc diameter fitted by the software should match this standard value. Any deviation directly reflects the measurement error of the probe itself. The ring gauge serves as the concentricity and shape reference, providing a precise inner cylindrical surface. Calibrating the steel sphere and ring gauge to concentricity fundamentally eliminates the reference error of the tooling itself, creating an ideal and known measurement environment. This allows all uncertainties in the profilometer's measurement results to be attributed to the calibrated object—the profilometer's probe and Z-axis accuracy—achieving error separation and maximizing calibration accuracy.

[0093] The calibration method described in this application employs a two-stage calibration mode, first calibrating the fixture and then calibrating the instrument. It utilizes the non-contact measurement of the image analyzer to establish a higher-level benchmark for the contact profilometer, achieving error separation and ensuring high benchmark reliability. A single method and fixture can complete comprehensive calibration of stylus dimensional accuracy, dual-stylus consistency, and Z-axis positioning accuracy, offering diverse functions. Precision mechanical adjustment and mathematical fitting algorithms are used to improve calibration accuracy to the micrometer level, resulting in high precision. The process is clear, with each step interconnected, reducing the time spent on repeated debugging and standard replacement, thus increasing efficiency.

[0094] 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 technical principles 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 calibration fixture for a dual-needle profilometer, characterized in that, include: The mounting base has a second through hole facing forward and backward. An adjusting seat is slidably fitted at the front end of the mounting base along the Z-axis direction, and the adjusting seat has a first through hole extending toward the second through hole; A micrometer screw gauge is vertically fixed on the mounting base. The measuring axis of the micrometer screw gauge is connected to the adjusting base and can drive the adjusting base to move up and down along the Z-axis. The ball-mounted assembly includes two tightening bolts threaded along the X-axis to both sides of the adjusting seat and coaxially arranged. A tightening area is formed between the ends of the two tightening bolts. The tightening area is located in the first through hole and its width and horizontal position are adjustable. A ring gauge is vertically mounted on the mounting base. The ring gauge has a through hole in its center, forming a first reference part. All or part of the first reference part is exposed and can be detected by an image instrument. The sphere is located within the tightening area and is tightened and fixed by the two tightening bolts. The sphere serves as a second reference part, which is located inside the first reference part and can be detected by the image instrument.

2. The dual-needle profilometer stylus calibration fixture as described in claim 1, characterized in that: The first through hole is strip-shaped and its length direction is parallel to the moving direction of the adjustment seat. The distance from the ball to the upper and lower ends of the first through hole is greater than the height of the probe of the profilometer.

3. The dual-needle profilometer stylus calibration fixture as described in claim 2, characterized in that: The upper or lower end of the first through hole is located outside the first reference portion and / or at least one edge of the adjustment seat is located inside the first reference portion.

4. The dual-needle profilometer stylus calibration fixture as described in claim 1, characterized in that: The adjusting seat has symmetrical threaded holes on both sides that connect to the first through hole. The axis of the threaded hole is parallel to the horizontal plane and perpendicular to the axis of the ring gauge. The tightening bolt is threaded into the threaded hole and can move along the X-axis.

5. The dual-needle profilometer stylus calibration fixture as described in claim 1, characterized in that: The mounting base includes a back plate, an upper clamping block mounted on the upper end of the back plate, and a lower clamping block disposed at the lower end of the back plate. A ring gauge mounting area is formed between the upper clamping block and the lower clamping block, which can clamp the outer wall of the ring gauge and radially limit the ring gauge. The front end of the ring gauge mounting area is provided with a plurality of pressure blocks that can be adjusted back and forth and used to axially press the ring gauge.

6. The dual-needle profilometer stylus calibration fixture as described in claim 5, characterized in that: The lower clamping block includes a lower clamping block seat fixed to the lower end of the back plate. Two lower clamping block bodies are mounted on the upper surface of the lower clamping block seat, and the distance between the two lower clamping block bodies is adjustable.

7. The dual-needle profilometer stylus calibration fixture as described in claim 6, characterized in that: The upper surface of the lower clamping block seat is provided with a strip-shaped groove along the X direction. The bottom surface of the lower clamping block body is provided with a protrusion that can be inserted into the strip-shaped groove and slide left and right. The bottom surface of the strip-shaped groove is provided with a strip-shaped mounting hole. The bolt passes through the mounting hole from bottom to top and connects to the lower clamping block body to fix the lower clamping block body.

8. The dual-needle profilometer stylus calibration fixture as described in claim 5, characterized in that: The upper clamping block and the lower clamping block are respectively provided with an upper connecting plate and a lower connecting plate at their front ends. The front ends of the upper connecting plate and the lower connecting plate are provided with sliding grooves along the Z-axis. Sliding seats are slidably installed in the two sliding grooves respectively. The adjusting seat is fixed between the two sliding seats. The measuring shaft of the micrometer is connected to the upper sliding seat. The pressure block is installed on the upper connecting plate and / or the lower connecting plate.

9. The dual-needle profilometer stylus calibration fixture as described in claim 1, characterized in that: The tightening bolt includes a fixed bolt and a movable bolt. The ends of the fixed bolt and the movable bolt are provided with operating parts for adjusting the horizontal position. The movable bolt includes a movable bolt body and a pressure column. The head of the movable bolt body is provided with a guide hole. The guide hole is coaxial with the movable bolt body. The pressure column is sleeved in the guide hole and can move axially. The guide hole is provided with an elastic component that makes the pressure column have an outward movement tendency to press the ball.

10. A calibration method using the dual-needle profilometer stylus calibration fixture as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Tooling calibration: S11. Use an image acquisition device to acquire images of the inner wall arc of the ring gauge and the outer wall arc of the sphere respectively. Use software to fit and obtain the fitted circles of the ring gauge and the sphere respectively, and calculate their center positions. S12. By operating the tightening bolt and the micrometer screw, adjust the spatial position of the sphere so that the positional deviation between the center of the sphere's fitting circle and the center of the ring gauge's fitting circle in the X and Z axis directions reaches the allowable threshold, forming a calibration fixture with the sphere's center and the ring gauge's center coaxial, thus completing the self-calibration of the calibration fixture. S2. Calibrate the profilometer probe: S21. Install the calibrated fixture onto the worktable and calibrate the dual-needle profilometer using at least one of the following methods; a. Control a single probe to scan the arc of the sphere, fit the diameter and compare it with the nominal diameter of the sphere to calculate the probe accuracy error; b. Control the two probes to scan the upper and lower arcs of the sphere respectively, fit the diameter and compare the difference to calculate the measurement accuracy error of the two probes; c. Move the ball vertically using a micrometer screw gauge and record the movement distance Z1. Scan the arc of the steel ball before and after the movement using a double probe and fit the center of the circle. Calculate the distance difference Z2 between the fitted centers before and after the movement. Compare Z1 and Z2 and calculate the measurement accuracy error. S3. Based on the error results of step S2, calibrate the probe of the dual-needle profilometer so that the values ​​measured by the two are consistent.

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