Large-size angle dial error calibration device

Abstract

The utility model discloses an error calibration device for a large-size angle dial. The error calibration device comprises a scribed line sighting device, a standard angle generating device, a concentric positioning device and a control system. According to the calibration device disclosed by the utility model, the large-view and high-definition electron microscope with the display screen is adopted as the core of the scribed line sighting device, so that the reading error is reduced, and the accuracy and reliability of the measurement result are ensured.

Description

Technical Field

[0001] This utility model belongs to the field of precision measurement, and specifically relates to a large-size angle scale error calibration device in this field. Background Art

[0002] An angle dial is a measuring instrument that indicates planar angles from 0° to 360° by regularly engraving lines on its surface. It is typically made of metal or a hard, non-magnetic material, and is usually circular or square with a diameter (side length) ranging from 100mm to 1500mm. The required angle scale is engraved along the dial surface using processes such as scribing and etching, with common graduations of 1° and 0.5°. Standard documents such as JJG628 "SLC9 Direct-Reading Current Meter", JJG 876 "Marine Meteorological Instruments", JJG 1167 "Marine Wind Measurement Instruments", JJG (Marine) 01 "FZS2. FZS1 Marine Data Buoy Sensors", and HYT 270 "Testing Methods for Marine Wind Measurement Instruments" all list the angle dial as one of the main standards for these marine-specific measuring instruments. However, a reliable calibration device and method are still lacking that can meet the requirements for angular error traceability of angle dials.

[0003] The angle error of the angle scale is usually calibrated by referring to the standard GB / T3177-2009 "Geometrical Specifications for Products (GPS) - Inspection of Dimensions of Smooth Workpieces". This indirect traceability method, which transmits angles from dimensional measurements, introduces significant measurement errors during the dimensional measurement process due to factors such as the consistency of the measuring instrument's positioning, measurement accuracy, and the selected measurement location. This, in turn, affects the accuracy of angle measurement. Compared to the direct traceability method of transmitting angles from dimensional measurements, the existing calibration method has disadvantages such as inaccurate measurement positioning, large amounts of measurement data, unreliable data conversion results, and low calibration efficiency.

[0004] For small-sized angle dials with a diameter φ≤300mm, direct measurement is performed using an image measuring instrument. The dial is placed horizontally with the scale facing upwards on the measuring platform of the image measuring instrument. The 0° (360°) graduation line direction is adjusted to be parallel to the longitudinal movement direction of the measuring platform. The measuring software sequentially extracts multiple circles and automatically fits them into the outer circle of the angle dial's graduation line, with the center of the circle defaulting to the rotation center of the angle dial. The nominal value α of the two measured angles is taken. A straight line parallel to the graduation line direction is constructed at the midpoint of the graduation line width of one measured angle. The intersection point of this straight line and the outer circle is constructed. The line L1 is the line connecting this intersection point and the center of the outer circle. The same method is used to construct the straight line L2 for the other measured angle. The angle α′ between lines L1 and L2 is the actual value of the two measured angles. The indication error δ is the difference between the nominal value and the actual value of the two measured angles (δ=α-α′). This method does not simulate working conditions when calibrating the small-angle dial. The image measuring instrument cannot accurately locate its machining geometric center through non-contact means, and the positioning deviation of the center directly affects the accuracy of the measurement results.

[0005] For large-size angle dials with a diameter φ > 300mm, which exceed the measuring range of general image measuring instruments, a digital caliper and steel ruler are used to calibrate the angle error of the angle dial using the chord length calculation method. The outer radius of the angle graduations and the chord length connecting the endpoints of the two graduations are measured, and the angle value is indirectly calculated using trigonometric functions. The difference between this value and the nominal value is the indication error δ. This method for calibrating large-size angle dials does not simulate working conditions and is affected by factors such as the accuracy limitations of the measuring instrument, large-size measurements, and combined measurements, resulting in lower measurement accuracy.

[0006] In summary, existing calibration schemes are not based on the actual working conditions of the angle dial and ignore the center positioning and zero-point aiming errors, resulting in poor measurement accuracy. In particular, for large-size angle dials, there are no good traceability devices and calibration methods, which cannot meet customers' measurement traceability needs. Utility Model Content

[0007] This invention addresses the following technical problems encountered when calibrating angle dials using conventional instruments and equipment: (1) inconsistent calibration principles prevent angle measurement; (2) incompatibility between large and small-sized angle dial calibration methods; and (3) inability to accurately locate the geometric center of the measured angle dial, resulting in significant errors in manual reading and low measurement accuracy. It provides a large-sized angle dial error calibration device and method that enables angle measurement and traceability, possesses high precision and a large range, and can accurately calibrate the indication error of angle dials of various sizes under simulated operating conditions.

[0008] The present invention adopts the following technical solution:

[0009] An improved large-size angle scale error calibration device includes a scale line aiming device, a standard angle generating device, a concentric positioning device, and a control system.

[0010] The described engraving and aiming device includes a base, a bracket mounted on the base, and an electron microscope with a display screen mounted on the bracket.

[0011] The standard angle generating device consists of a circular grating and a reading head, with the reading head fixedly mounted on a bracket parallel to the circular grating.

[0012] The concentric positioning device includes a servo turntable driven by a motor, a circular grating support frame on the top of the servo turntable, the circular grating being sleeved on the outside of the circular grating support frame, a marble platform on the top of the circular grating support frame, the circular grating support frame and the marble platform being able to rotate synchronously with the servo turntable, and four or more track grooves extending from the center to the edge on the top of the marble platform, a clamping mechanism that can slide along the track groove being provided in each track groove, and a scale being provided on four of the track grooves;

[0013] The control system includes a controller and an input device, a fine-tuning handwheel, a display device, and a motor electrically connected to the controller. The controller can control the motor to work according to the input from the input device or the fine-tuning handwheel, and the display device displays the input content of the input device. The reading head is electrically connected to the display device through a conversion module, and the conversion module can read the reading from the reading head and display it through the display device.

[0014] Furthermore, a track groove pointing towards the center of the marble platform is provided on the base of the engraving aiming device. A lead screw is installed in the track groove, and one end of the lead screw is fixedly connected to a handle outside the track groove. The bracket is installed on the lead screw, and rotating the handle allows the bracket to slide along the lead screw. A thread is provided on the outer wall of the bracket, and a turntable is screwed onto the thread. One end of the support rod is inserted into the bracket and supported by the turntable, and the other end is equipped with an electron microscope.

[0015] Furthermore, two or more locking mechanisms are installed at the bottom of the bracket.

[0016] Furthermore, the motor, servo turntable, and circular grating support frame of the concentric positioning device are all installed inside the housing, and the marble platform is located on the top of the housing.

[0017] Furthermore, the top of the servo turntable is a rotary worktable with a recess, and the bottom of the circular grating support frame has a boss that is embedded in the recess. The rotary worktable and the circular grating support frame are fitted with a basic hole system and are positioned by two cylindrical locating pins and fastened with ten hexagon socket screws.

[0018] Furthermore, the outer side of the circular grating support frame is a conical surface, and the circular grating is fastened to the outer conical surface of the circular grating support frame using three or more hexagonal screws.

[0019] Furthermore, a hole is made in the center of the marble platform, and a boss is set at the top center of the circular grating support frame. The boss is inserted into the hole, and a dial center positioning device is installed in the boss. The marble platform and the circular grating support frame are fastened together by three or more bolts.

[0020] Furthermore, eight track grooves extending from the center to the edge are set on the top of the marble platform. The eight track grooves are evenly distributed on the marble platform, and scales are set at intervals between the track grooves.

[0021] An improvement of the calibration method using the above-mentioned calibration device is as follows: the scale of the angle to be measured is fixed upward on a marble platform, the handle is rotated to adjust the position of the scale alignment device bracket so that the optical probe of the electron microscope is facing the scale of the angle to be measured, and the crosshairs displayed on the electron microscope display screen are illuminated on the scale of the angle to be measured. The focus is adjusted so that the scale of the angle to be measured displayed on the electron microscope display screen is clear.

[0022] Commands are sent to the controller via the input device or fine-tuning handwheel. The controller then controls the motor to drive the servo turntable, circular grating support frame, marble platform, and the measured angle scale on the marble platform to rotate synchronously. This aligns the center point of the crosshairs displayed on the electron microscope screen with the middle position of the 0° and 360° scale widths on the measured angle scale. The conversion module obtains the rotation angle of the circular grating through the reading head as the rotation angle displayed on the display device. The input device is then used to reset the rotation angle displayed on the display device to zero.

[0023] The input device sends a rotation angle command to the controller, which then controls the motor to drive the servo turntable, circular grating support frame, marble platform, and the measured angle scale on the marble platform to rotate synchronously. The motor stops when the commanded angle is reached. The fine-tuning handwheel sends a command to the controller, which then controls the motor to drive the servo turntable, circular grating support frame, marble platform, and the measured angle scale on the marble platform to rotate synchronously. When the center point of the crosshair displayed on the electron microscope screen aligns with the middle position of the α mark width on the measured angle scale, the controller stops the motor. At this time, the rotation angle displayed on the device is α', and the angle indication error of this measurement is δ = α - α'. Repeat this section, selecting 6 to 12 marks along the circumference of the measured angle scale for measurement. The obtained δi is the angle indication error of each measured angle on the measured angle scale, where i = 1, 2, ..., n, and n is a natural number.

[0024] Furthermore, when fixing the angle dial to be measured on the marble platform, if the angle dial to be measured has a center hole, then the center hole of the angle dial to be measured is fitted onto the dial center positioning device and clamped by the clamping mechanism; if the angle dial to be measured does not have a center hole, then the dial center positioning device is removed, the angle dial to be measured is placed on the marble platform, so that its center falls into the center opening of the marble platform, and the distance from the outer edge of the angle dial to the center is calculated by the readings of the four scales pressed against its outer edge, the angle dial to be measured is manually fine-tuned so that the readings of the outer edge pressed against the four scales are consistent, and then clamped by the clamping mechanism.

[0025] The beneficial effects of this utility model are:

[0026] The calibration device disclosed in this utility model uses a large-field-of-view, high-definition electron microscope with a display screen as the core of the engraving aiming device, reducing reading errors and ensuring the accuracy and reliability of measurement results; it uses a large-size, high-precision circular grating as the standard angle generating device, ensuring the consistency of inner and outer ring angles and measurement accuracy; it uses a large-size marble platform, which can meet the calibration requirements of angle dials of various specifications; the servo turntable, circular grating support frame, and marble platform form a three-in-one concentric positioning device, ensuring the synchronous rotation of the servo turntable, circular grating support frame, marble platform, and the angle dial being measured, accurately simulating the actual working conditions of the angle dial being measured, and reducing the uncertainty of calibration results; the track groove and scale set on the top of the marble platform can accurately center the angle dials with different shapes and structures.

[0027] The calibration method disclosed in this utility model adopts the traceability method of angle measurement and angle transmission, which can completely simulate the actual working conditions of the measured angle scale, improve the measurement accuracy and detection efficiency, meet the angle error calibration of various sizes and shapes of angle scales, and can achieve independent calibration and traceability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the calibration device disclosed in this utility model;

[0029] Figure 2 This is a schematic diagram of the components of a concentric positioning device;

[0030] Figure 3 This is a schematic diagram showing the distribution of the track grooves and scale on the top of the marble platform;

[0031] Figure 4 This is a schematic diagram of the outer conical surface of the circular grating support frame;

[0032] Figure 5 This is a schematic diagram showing the installation position of the dial center positioning device.

[0033] Reference numerals: 1—Scale line aiming device, 11—Lead screw, 12—Handle, 13—Turntable, 14—Display device, 16—Fine adjustment handwheel, 2—Concentric positioning device, 21—Servo turntable, 22—Circular grating support frame, 23—Circular grating, 24—Marble platform, 25—Cylindrical positioning pin, 26—Scale center positioning device, 27—Railway groove, 28—Clamping mechanism, 29—Scale. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0035] Example 1: This example discloses a large-size angle scale error calibration device, such as... Figure 1 As shown, it includes a scribing aiming device 1, a standard angle generating device, a concentric positioning device 2, and a control system (not shown in the figure).

[0036] The described engraving and aiming device includes a base, a bracket mounted on the base, and a large-field electron microscope with a display screen mounted on the bracket.

[0037] The standard angle generator is the core device, which mainly uses a circular grating and a reading head. The circular grating is composed of a large number of high-precision grating lines engraved on a stainless steel cylindrical surface. The engraving accuracy is ±0.5″, the period error is less than ±40nm, and the repeatability is 0.02 seconds. The matching reading head is a high-precision reading head with an advanced optical filtering system, excellent signal stability and very low electronic subdivision error. The reading head is fixedly mounted on a bracket parallel to the circular grating.

[0038] like Figure 2 As shown, the concentric positioning device 2 includes a servo turntable 21 driven to rotate by a motor, a circular grating support frame 22 is provided on the top of the servo turntable, the circular grating 23 is sleeved on the outside of the circular grating support frame, and a marble platform 24 is provided on the top of the circular grating support frame. The circular grating support frame and the marble platform can rotate synchronously with the servo turntable. Figure 3 As shown, eight track grooves 27 extending from the center to the edge are provided on the top of the marble platform. The eight track grooves are evenly distributed on the marble platform. A clamping mechanism 28 that can slide along the track groove is provided in each track groove. A scale 29 is also provided on four of the track grooves, and the scale is provided at intervals between the track grooves to position the dial of the angle being measured.

[0039] The control system includes a controller (PLC programmable controller) and an input device, a fine-tuning handwheel 16, a display device 14, and a motor electrically connected to the controller. The controller can control the motor to work according to the input from the input device or the fine-tuning handwheel. Specifically, the controller converts the rotation angle command into a signal recognizable by the motor driver. The motor driver receives and amplifies the signal before driving the motor to rotate the command angle. The display device displays the input content from the input device. The display device can be a touch screen that integrates the input device. A high-precision reading head is electrically connected to the display device through a conversion module. The high-precision reading head automatically reads the rotation angle of the circular grating, and the conversion module reads the reading from the high-precision reading head and displays it on the display device.

[0040] A track groove pointing towards the center of the marble platform is provided on the base of the engraving aiming device. A lead screw 11 is installed in the track groove, and one end of the lead screw is fixedly connected to a handle 12 outside the track groove. The bracket is installed on the lead screw, and rotating the handle allows the bracket to slide along the lead screw. A thread is provided on the outer wall of the bracket, and a turntable 13 is screwed onto the thread. One end of a support rod is inserted into the bracket and supported by the turntable, and the other end is equipped with an electron microscope. Rotating the turntable can raise and lower the support rod and the electron microscope. This height-adjustable design can meet the engraving aiming requirements of angle dials with a size range of 100mm to 1500mm. Two or more locking mechanisms are provided at the bottom of the bracket for locking and fixing the bracket.

[0041] The motor, servo turntable, and circular grating support frame of the concentric positioning device are all installed inside the housing, while the marble platform is located on the top of the housing.

[0042] To ensure that the rotation centers of all components in the concentric positioning device are consistent, all components adopt the same design datum. The top of the servo turntable is a rotary worktable with a recess, and the bottom of the circular grating support frame has a boss that is embedded in the recess. The rotary worktable and the circular grating support frame are fitted with a hole-based system and positioned using two cylindrical locating pins 25. The boss and locating pins work together to achieve complete positioning between the servo turntable and the circular grating support frame, and the parts are secured with ten hexagonal socket head cap screws.

[0043] like Figure 4 As shown, the outer side of the circular grating support frame is a conical surface to facilitate concentric alignment during installation. Three or more hexagonal screws are used to fasten the circular grating to the outer conical surface of the circular grating support frame, which can not only compensate for eccentricity but also provide excellent mechanical stability and resist thermal cycling, impact and vibration.

[0044] like Figure 5As shown, a hole is made in the center of the marble platform, and a boss is set at the top center of the circular grating support frame. The boss is inserted into the hole, and a dial center positioning device 26 is installed in the boss. The marble platform and the circular grating support frame are fastened with more than three bolts to ensure that the servo turntable, the circular grating support frame, the circular grating and the marble platform rotate synchronously and are concentrically aligned.

[0045] This embodiment also discloses a calibration method. Using the above-described calibration device, the scale of the angle to be measured is fixed upwards on a marble platform to ensure accurate center positioning of the scale before measurement. The handle is rotated to adjust the position of the alignment device bracket, so that the optical probe of the electron microscope is directly facing the scale of the angle to be measured, and the crosshairs displayed on the electron microscope screen are illuminated on the scale of the angle to be measured. The focus is adjusted to make the scale of the angle to be measured displayed on the electron microscope screen clear.

[0046] Commands are sent to the controller via the input device or fine-tuning handwheel. The controller then controls the motor to drive the servo turntable, circular grating support frame, marble platform, and the measured angle scale on the marble platform to rotate synchronously. This aligns the center point of the crosshair displayed on the electron microscope screen with the middle position of the 0° (360°, where the 0° and 360° scales on the angle scale coincide) line width of the measured angle scale. The conversion module obtains the rotation angle of the circular grating through a high-precision reading head as the rotation angle displayed on the device. The input device is then used to reset the rotation angle displayed on the device to zero.

[0047] The input device sends a rotation angle command to the controller, which then controls the motor to drive the servo turntable, circular grating support frame, marble platform, and the measured angle scale on the marble platform to rotate synchronously. The motor stops when the commanded angle is reached. The fine-tuning handwheel sends another command to the controller, which then controls the motor to drive the servo turntable, circular grating support frame, marble platform, and the measured angle scale on the marble platform to rotate synchronously. When the center point of the crosshair displayed on the electron microscope screen aligns with the middle position of the α mark width on the measured angle scale, the controller stops the motor. At this point, the rotation angle displayed on the device is α', and the angle indication error for this measurement is δ = α - α'. For example, if the target α mark is 30°, the rotation angle command sent to the controller via the input device would be a value close to 30°, such as 29.9°. It is not directly set to 30° because the measured angle scale has errors; the actual rotation degree is inconsistent with the mark on the measured angle scale. The command value is slightly smaller than 30° to avoid backlash. After rotating 29.9°, use the fine-tuning handwheel to control the rotation until the center point of the crosshair aligns with the middle position of the 30° mark width on the angle scale being measured. At this point, the actual rotation angle displayed on the device is α'. Subtracting α' from 30° gives the angle indication error δ of this measurement. A pulse transmitter is used as the fine-tuning method. The fine-tuning handwheel has a rotary switch, a main knob, and a magnification adjustment knob. The magnification adjustment knob has ×1 (fine-tuning), ×10, and ×100 (fast magnification adjustment). Repeat this section, selecting 6 to 12 marks along the circumference of the angle scale being measured, until all marks on the circumference of the angle scale are measured. The resulting δi is the angle indication error (unit: °) for each measured angle on the angle scale, i = 1, 2…n, where n is a natural number.

[0048] When fixing the angle dial to be measured on the marble platform, if the angle dial to be measured has a center hole, then fit the center hole of the angle dial to be measured onto the dial center positioning device and clamp it with the clamping mechanism; if the angle dial to be measured does not have a center hole, then remove the dial center positioning device, place the angle dial to be measured on the marble platform, and make its center fall into the center opening of the marble platform. Calculate the distance from the outer edge of the angle dial to the center by reading the four scales pressed against its outer edge. Manually fine-tune the angle dial to be measured so that the readings of the outer edge pressed against the four scales are consistent, and then clamp it with the clamping mechanism.

Claims

1. A large-size angle scale error calibration device, characterized in that: It includes a scribing aiming device, a standard angle generating device, a concentric positioning device, and a control system; The described engraving and aiming device includes a base, a bracket mounted on the base, and an electron microscope with a display screen mounted on the bracket. The standard angle generating device consists of a circular grating and a reading head, with the reading head fixedly mounted on a bracket parallel to the circular grating. The concentric positioning device includes a servo turntable driven by a motor, a circular grating support frame on the top of the servo turntable, the circular grating being sleeved on the outside of the circular grating support frame, a marble platform on the top of the circular grating support frame, the circular grating support frame and the marble platform being able to rotate synchronously with the servo turntable, and four or more track grooves extending from the center to the edge on the top of the marble platform, a clamping mechanism that can slide along the track groove being provided in each track groove, and a scale being provided on four of the track grooves; The control system includes a controller and an input device, a fine-tuning handwheel, a display device, and a motor electrically connected to the controller. The controller can control the motor to work according to the input from the input device or the fine-tuning handwheel, and the display device displays the input content of the input device. The reading head is electrically connected to the display device through a conversion module, and the conversion module can read the reading from the reading head and display it through the display device.

2. The large-size angle scale error calibration device according to claim 1, characterized in that: A track groove pointing to the center of the marble platform is set on the base of the engraving aiming device. A lead screw is installed in the track groove. One end of the lead screw is fixedly connected to a handle outside the track groove. The bracket is installed on the lead screw. Rotating the handle can make the bracket slide along the lead screw. A thread is set on the outer wall of the bracket. A turntable is screwed on the thread. One end of the support rod is inserted into the bracket and supported by the turntable. The other end is equipped with an electron microscope.

3. The large-size angle scale error calibration device according to claim 2, characterized in that: Two or more locking mechanisms are installed at the bottom of the bracket.

4. The large-size angle scale error calibration device according to claim 1, characterized in that: The motor, servo turntable, and circular grating support frame of the concentric positioning device are all installed inside the housing, while the marble platform is located on the top of the housing.

5. The large-size angle scale error calibration device according to claim 1, characterized in that: The top of the servo turntable is a rotary worktable with a recess, and the bottom of the circular grating support frame has a boss that is embedded in the recess. The rotary worktable and the circular grating support frame are fitted with a basic hole system and are positioned by two cylindrical locating pins and fastened with ten hexagon socket screws.

6. The large-size angle scale error calibration device according to claim 1, characterized in that: The outer side of the circular grating support frame is a conical surface. The circular grating is fastened to the outer conical surface of the circular grating support frame using three or more hex socket screws.

7. The large-size angle scale error calibration device according to claim 2, characterized in that: A hole is made in the center of the marble platform, and a boss is set at the top center of the circular grating support frame. The boss is inserted into the hole, and a dial center positioning device is installed in the boss. The marble platform and the circular grating support frame are fastened together with three or more bolts.

8. The large-size angle scale error calibration device according to claim 1, characterized in that: Eight track grooves extending from the center to the edge are installed on the top of the marble platform. The eight track grooves are evenly distributed on the marble platform, and scales are installed at intervals in the track grooves.

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