Method for establishing measurement coordinate system of side-mounted gear measuring machine based on PSD laser ranging

Abstract

The present invention relates to the technical field of coordinate measuring machines, and specifically to a method for establishing a measurement coordinate system of a side-mounted gear measuring machine based on PSD laser ranging. This is to overcome the problems in the prior art that the measurement accuracy is not high enough and the loading and unloading of large-sized standard blocks is difficult, and they are not suitable for establishing a large gear measurement coordinate system. The technical solution adopted by the present invention first uses a PSD displacement sensor to level the machine coordinate system and the workpiece coordinate system, and uses a laser absolute distance meter to measure two points on the large gear chord respectively to achieve the X-direction midpoint measurement of the center of rotation; the two-dimensional PSD displacement sensor cooperates with the measuring machine T-axis grating ruler to complete the Y-direction midpoint detection of the large gear, thereby determining the position of the large gear rotation center, and finally realizes the unification of the workpiece coordinate system and the measurement coordinate system through the spatial transformation of the coordinate system.

Description

Technical Field

[0001] The invention relates to the technical field of coordinate measuring machines, and in particular to a method for establishing a measuring coordinate system of a side-mounted gear measuring machine based on PSD laser ranging. Background Art

[0002] Large gears are key transmission components of large equipment. With the wide application of large gears in the fields of ships, energy power machinery, aviation transmission systems, etc. and the increasing market demand, the requirements for their performance and quality are getting higher and higher. Therefore, high-precision measurement of large gears as a means of ensuring their performance and quality has become increasingly urgent and important.

[0003] As an ideal measurement method for large gears in the machine, the side-mounted measurement is to place the gear measuring device next to the large gear processing machine to detect various gear parameters. In order to ensure its higher measurement accuracy, it is necessary to consider how to accurately locate the position of the measuring instrument and the gear to be measured, that is, to measure the coordinates of the rotation center of the large gear in the measuring machine coordinate system, and to establish the measurement coordinate system of the large gear with the rotation center of the large gear to be measured as the zero point. Due to the large diameter of the gear to be measured and the short R-axis stroke of the side-mounted measuring machine, the commonly used standard ball and standard mandrel methods cannot pass through the rotation center of the large gear, so these methods are only suitable for the establishment of the measurement coordinate system of small and medium-sized gears, not for the establishment of the measurement coordinate system of large gears. When measuring based on the laser tracking technology method, there is an angle measurement error due to the limitation of the angle resolution, and this error will be further amplified as the distance increases, and its measurement accuracy cannot be guaranteed. The large-size standard gauge block method can achieve coordinate establishment. As the size of the gear to be measured continues to increase, the accuracy of the corresponding large-size standard gauge block is difficult to guarantee, and the loading and unloading of the large-size standard gauge block during its use is more difficult.

[0004] Therefore, it can be seen that the existing methods for establishing the large gear measurement coordinate system still have certain limitations, and there is currently a lack of effective countermeasures for establishing the large gear measurement coordinate system. Summary of the invention

[0005] The present invention aims to provide a method for establishing a measurement coordinate system of a side-mounted gear measuring machine based on PSD laser ranging, so as to overcome the problems in the prior art of insufficient measurement accuracy and difficulty in loading and unloading large-sized standard blocks, both of which are not suitable for establishing a measurement coordinate system for large gears.

[0006] In order to overcome the problems existing in the prior art, the technical solution of the present invention is: a method for establishing a measurement coordinate system of a side-mounted gear measuring machine based on PSD laser ranging, firstly, a PSD displacement sensor is used to level the machine coordinate system and the workpiece coordinate system, and a laser absolute distance meter is used to respectively measure two points on the chord of the large gear to achieve the measurement of the midpoint of the rotation center in the X direction; the two-dimensional PSD displacement sensor cooperates with the T-axis grating ruler of the measuring machine to complete the Y-direction midpoint detection of the large gear, thereby determining the position of the rotation center of the large gear, and finally the spatial transformation of the coordinate system is used to achieve the unification of the workpiece coordinate system and the measurement coordinate system.

[0007] The above method specifically comprises the following steps:

[0008] Step 1: Level the machine coordinate system and the workpiece coordinate system:

[0009] Use a side-mounted measuring machine that has been leveled and calibrated to place the PSD displacement sensor at the edge of the rotary table in the X direction, then rotate the rotary table 180°, observe the indications of the PSD displacement sensors at two positions, and adjust the angle of the rotary table in the X direction until the difference between the PSD displacement sensors in the forward and backward positions of the X direction is equal, thus completing the leveling of the rotary table in the X direction;

[0010] Similarly, rotate the rotary table so that the PSD displacement sensor is in the Y direction of the rotary table, and adjust the Y direction of the rotary table to be horizontal;

[0011] Step 2: Use the PSD displacement sensor and the laser absolute distance meter to measure the X-axis midpoint of the large gear:

[0012] 1) The large gear to be tested is placed on a rotary table;

[0013] 2) First, select any chord ab near the circumferential diameter of the gear in the X-axis direction, and move the absolute laser rangefinder to the extension line of the chord ab, that is, the 1st station;

[0014] 3) Place the PSD displacement sensor and the target ball at position a and make fine adjustments so that the absolute laser rangefinder and the target ball are connected to light, measure the distance x1 with the absolute laser rangefinder, and record the X and Y coordinates of the PSD displacement sensor;

[0015] Step 3: Get the X-direction coordinate value of the rotation center:

[0016] Rotate the rotary table, turn the PSD displacement sensor and the target ball to position b, rotate to ensure that the target ball is connected to the light, adjust the gear posture until the difference between the PSD displacement sensors at positions a and b in the X direction is equal to ensure that the straight line where points a and b are located is parallel to the X axis. The absolute laser rangefinder measures the distance x 2 , you can get the X-direction coordinate value of the rotation center:

[0017]

[0018] Step 4: Use the PSD displacement sensor and the measuring machine's T-axis grating to measure the Y-axis midpoint of the large gear:

[0019] Rotate the rotary table counterclockwise to make the PSD displacement sensor and the target ball move to position c. Move the measuring machine T axis to make the absolute laser rangefinder connect with the target ball. After the PSD displacement sensor reading stabilizes, the X-direction offset x of position c is obtained. 3 , by comparing x 3 With x 0 Fine-tune the measuring machine T axis position, when x 3 Equal to x 0 At this time, record the T-axis grating indication of the measuring machine as y 1 ; Step 5: Get the Y-direction coordinate value of the rotation center:

[0020] Rotate the rotary table to make the PSD displacement sensor and the target ball move to position d. Move the measuring machine T axis to make the absolute laser rangefinder connect with the target ball. The PSD displacement sensor reading is stable, and the X-direction offset x of position d is obtained. 4 , by comparing x 4 With x 0 The size of the measuring machine T axis position is fine-tuned. 4 Equal to x 0 At this time, record the T-axis grating indication of the measuring machine as y 2 , you can get the Y-direction coordinate value of the rotation center:

[0021]

[0022] Step 6: Obtain the position O(x 0 ,y 0 ), move the origin of the coordinate system of the side-mounted measuring machine to coincide with the center of rotation of the gear, and establish the measurement coordinate system of the side-mounted large gear.

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] 1. The present invention adopts a measurement method combining an absolute laser rangefinder with a PSD displacement sensor, which eliminates the angle error caused by insufficient angle measurement resolution of the laser tracker and avoids the reduction of measurement accuracy and increase of uncertainty due to large angle error.

[0025] 2. The present invention uses a laser rangefinder with high distance measurement accuracy and only one-dimensional measurement function to replace the laser tracker. The measured distance is an absolute distance, which avoids the influence of interrupted light in the process of using a laser interferometer to measure the distance, and is easier to implement in engineering.

[0026] 3. The present invention is applied to the establishment of a coordinate system for a side-mounted large gear. The present invention proposes to use an optical method, combined with a laser absolute distance meter and a PSD displacement sensor to solve the problem of establishing a coordinate system for a side-mounted large gear, and can accurately find the rotation center of the large gear, solving the problem that the probe of the side-mounted gear measuring machine cannot reach the origin of the measurement coordinate system (gear rotation center). The laser-based optical measurement method used can break through the original measurement distance limitation and realize the measurement of large gears with arbitrary diameters.

[0027] 4. The present invention utilizes the coordinate system of the measuring machine itself. After the measuring machine leaves the factory, the components of the laser and the rangefinder are used as accessories of the measuring machine, and the parallelism of the light beams of the two beams with the X-axis of the measuring machine has been achieved. When measuring on site, only the first step of the leveling process of the machine coordinate system and the workpiece coordinate system in the specific steps needs to be considered. The operation is relatively simple to implement, and the error term introduced is only the uncertainty of the center coordinate of the workpiece gear coordinate system, which makes it easy to achieve high-precision measurement of large gears. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of a measurement coordinate system establishment system of the method of the present invention;

[0029] Figure 2 It is the measurement principle diagram of the method of the present invention.

[0030] The reference numerals are as follows:

[0031] 1-PSD displacement sensor; 2-target ball; 3-magnetic table base; 4-large gear to be measured; 5-rotary worktable; 6-side mounted gear measuring machine; 7-laser absolute distance meter; 8-laser transmitter. DETAILED DESCRIPTION

[0032] The method of the present invention is described in detail below with reference to the accompanying drawings.

[0033] See also Figure 1 : In order to ensure the effective measurement of the method of the present invention within the measuring range, the large gear 4 to be measured is placed on the rotary table 5, and the PSD displacement sensor 1 and the target ball 2 are coaxially integrated and fixed to the large gear 4 to be measured through the magnetic table base 3. The distance from the rotation center of the gear 4 to the position where it is placed should be less than half of the travel range of the T axis of the measuring machine 6. The laser transmitter 8 is fixed on the upper part of the absolute laser rangefinder 7, and the absolute laser rangefinder 7 is fixed on the T axis of the measuring machine 6. In this way, it is ensured that the two light rays are parallel to the X-axis coordinate axis of the measuring machine 6.

[0034] Machine coordinate system: refers to the coordinate system established along the three-axis motion law of the side-mounted gear measuring machine. Workpiece coordinate system: refers to the coordinate system established with the rotation center of the large gear 4 being measured as the coordinate origin.

[0035] Measurement coordinate system: refers to the coordinate system established to evaluate various parameters of gears.

[0036] See also Figure 2 After confirming that the above devices are connected correctly, the coordinate system establishment method of the side-mounted gear measuring machine based on PSD laser ranging provided by the present invention is used to detect the rotation center coordinate O (x 0 ,y 0 ), the specific implementation steps are:

[0037] Step 1: Level the machine coordinate system and the workpiece coordinate system:

[0038] When using the side-mounted measuring machine 6 after leveling and calibration, it is only necessary to adjust the level of the rotary table 5 to ensure that it is parallel to the translation axis of the measuring machine.

[0039] Use the laser transmitter 8 and the PSD displacement sensor 1 to level the rotary table 5. Place the PSD displacement sensor 1 at the edge of the rotary table 5 in the X direction. Then rotate the rotary table 5 180° and observe the indications of the PSD displacement sensor 1 at two positions. Adjust the X-direction angle of the rotary table 5 until the difference between the forward and rearward positions of the PSD displacement sensor 1 is equal. This means that the rotary table is level in the X direction.

[0040] Similarly, the rotary table 5 is rotated to place the PSD displacement sensor 1 in the Y direction of the rotary table 5 , and the Y level of the rotary table 5 is adjusted to achieve parallelism between the machine coordinate system and the workpiece coordinate system.

[0041] Step 2: Use the PSD displacement sensor and the laser absolute distance meter to measure the X-axis midpoint of the large gear:

[0042] 1) The gear 4 to be measured is placed on the rotary table 5.

[0043] 2) ab is an arbitrary chord near the circumferential diameter of the gear 4 in the X-axis direction. During measurement, the position moved by the absolute laser rangefinder 7 is on the extension line of the chord ab, that is, the 1st station.

[0044] 3) Place the PSD displacement sensor 1 and the target ball 2 at position a and make fine adjustments so that the absolute laser rangefinder 7 and the target ball 2 receive light, measure the distance x1 with the absolute laser rangefinder 7, and record the X, Y coordinates of the PSD displacement sensor 1.

[0045] Step 3: Get the X-direction coordinate value of the rotation center

[0046] Rotate the rotary table 5 to turn the PSD displacement sensor 1 and the target ball 2 to the b position and make fine adjustments to ensure that the target ball 2 is connected to the light. Adjust the posture of the gear 4 so that the Y-direction offset of the PSD displacement sensor 1 is the same as that at the a position to ensure that the straight line where the two points a and b are located is parallel to the X axis. The absolute laser rangefinder 7 measures the distance x 2 , you can get the X-direction coordinate value of the rotation center:

[0047]

[0048] Step 4: Use the PSD displacement sensor and the measuring machine's T-axis grating to measure the Y-axis midpoint of the large gear:

[0049] Rotate the rotary table 5 counterclockwise to make the PSD displacement sensor 1 and the target ball 2 move to the c position. Move the T axis of the measuring machine 6 to make the absolute laser rangefinder 7 connect with the target ball 2. Fine-tune the PSD displacement sensor 1 to make the reading stable, and obtain the X-direction offset x of the position c. 3 , by comparing x 3 With x 0 The size of the measuring machine 6 is used to fine-tune the T-axis position. 3 Equal to x 0 When the measuring machine 6 has the T-axis grating value y 1 ;

[0050] Step 5: Get the Y-direction coordinate value of the rotation center:

[0051] Rotate the rotary table 5 to make the PSD displacement sensor 1 and the target ball 2 rotate to the position d. Move the measuring machine 6T axis to make the absolute laser rangefinder 7 connect with the target ball 2. The reading of the PSD displacement sensor 1 is stable, and the X-direction offset x of the position d is obtained. 4 , by comparing x 4 With x 0 The size of the measuring machine 6 is used to fine-tune the T-axis position. 4 Equal to x 0 At this time, record the measuring machine 6T axis grating indication value y 2 , you can get the Y-direction coordinate value of the rotation center:

[0052]

[0053] Step 6: The above steps can obtain the position O(x 0 ,y 0 ), move the origin of the coordinate system of the side-mounted measuring machine to coincide with the center of rotation of the gear, thus realizing the establishment of the measurement coordinate system of the side-mounted large gear.

[0054] In order to verify the above results, the T-axis movement of the measuring machine 6 is fine-tuned to move the absolute laser rangefinder 7 until the T-axis grating reading is y 0 The PSD displacement sensor 1 and the target ball 2 are placed at position e, and the absolute laser rangefinder 7 measures x 5 , rotate the rotary table 5 so that the PSD displacement sensor 1 and the target ball 2 are placed at position f, and the absolute laser rangefinder 7 measures x 6 , then when:

[0055]

[0056] This set of data is considered reliable.

Claims

1. A method for establishing a measurement coordinate system of a side-mounted gear measuring machine based on PSD laser ranging. Features: Firstly, the PSD displacement sensor is used to level the machine coordinate system and the workpiece coordinate system, and the laser absolute distance meter is used to measure two points on the chord of the large gear respectively to realize the measurement of the midpoint of the rotation center in the X direction; the two-dimensional PSD displacement sensor is used in conjunction with the T-axis grating ruler of the measuring machine to complete the Y-direction midpoint detection of the large gear, thereby determining the position of the rotation center of the large gear. Finally, the spatial transformation of the coordinate system is used to realize the unification of the workpiece coordinate system and the measurement coordinate system. The specific steps include: Step 1: Level the machine coordinate system and the workpiece coordinate system: Use the side-mounted measuring machine (6) that has been leveled and calibrated to place the PSD displacement sensor (1) at the edge of the rotary table (5) in the X direction, then rotate the rotary table 180°, observe the indications of the PSD displacement sensor (1) at the two positions, and adjust the angle of the rotary table (5) in the X direction until the difference between the PSD displacement sensor (1) in the forward and backward positions of the X direction is equal, thus completing the leveling of the rotary table in the X direction; Similarly, the rotary table (5) is rotated so that the PSD displacement sensor (1) is located in the Y direction of the rotary table (5), and the Y direction of the rotary table is adjusted to be horizontal; Step 2: Use the PSD displacement sensor and the laser absolute distance meter to measure the X-axis midpoint of the large gear: 1) The large gear (4) to be measured is placed on a rotary table (5); 2) Firstly, select any chord ab near the circumference diameter of the gear (4) in the X-axis direction, and move the absolute laser rangefinder (7) to the position on the extension line of the chord ab, i.e., the 1st station; 3) Place the PSD displacement sensor (1) and the target ball (2) at position a and make fine adjustments so that the absolute laser rangefinder (7) and the target ball (2) are connected to light, and the distance x is measured by the absolute laser rangefinder (7). 1 , and record the X and Y coordinates of the PSD displacement sensor (1); Step 3: Get the X-direction coordinate value of the rotation center: Rotate the rotary table (5) to move the PSD displacement sensor (1) and the target ball (2) to position b. Rotate to ensure that the target ball (2) is exposed to light. Adjust the gear (4) until the difference between the PSD displacement sensor (1) at positions a and b in the X direction is equal to ensure that the straight line where points a and b are located is parallel to the X axis. The absolute laser rangefinder (7) measures the distance x 2 , you can get the X-direction coordinate value of the rotation center: Step 4: Use the PSD displacement sensor and the measuring machine's T-axis grating to measure the Y-axis midpoint of the large gear: The rotary table (5) is rotated counterclockwise to make the PSD displacement sensor (1) and the target ball (2) rotate to the c position. The T axis of the measuring machine (6) is moved to make the absolute laser rangefinder (7) connect with the target ball (2). After the reading of the PSD displacement sensor (1) is stable, the X-direction offset x of the c position is obtained. 3 , by comparing x 3 With x 0 The size of the fine-tuning measuring machine (6) T axis position, when x 3 Equal to x 0 At this time, record the T-axis grating indication of the measuring machine (6) as y 1 ; Step 5: Get the Y-direction coordinate value of the rotation center: The rotary table (5) is rotated to make the PSD displacement sensor (1) and the target ball (2) rotate to the position d, and the T axis of the measuring machine (6) is moved to make the absolute laser distance meter (7) and the target ball (2) connect light, and the reading of the PSD displacement sensor (1) is stable, and the X-direction offset x of the position d is obtained. 4 , by comparing x 4 With x 0 The size of the measuring machine (6) is used to fine-tune the T axis position. 4 Equal to x 0 At this time, record the T-axis grating indication of the measuring machine (6) as y 2 , you can get the Y-direction coordinate value of the rotation center: Step 6: Obtain the position O(x 0 ,y 0 ), the origin of the coordinate system of the side-mounted measuring machine (6) is moved to coincide with the rotation center position of the gear (4), thereby establishing the measurement coordinate system of the side-mounted large gear.

Images