CN116442000A - Calibrating device and calibrating method for measuring head pre-stroke of numerical control machine tool in-situ detection system - Google Patents
Calibrating device and calibrating method for measuring head pre-stroke of numerical control machine tool in-situ detection system Download PDFInfo
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Abstract
The invention discloses a calibrating device for a pre-stroke of a measuring head of a numerical control machine tool in-situ detection system, which comprises a trigger measuring head, wherein a probe is arranged at the end part of the trigger measuring head, a regular triangular pyramid is arranged at the vertically corresponding position of the bottom of the probe, the top end of an extension rod is contacted with the bottom of the regular triangular pyramid and is mutually fixed, the bottom end of the extension rod is fixed with a magnetic gauge stand, and a limiting structure is further arranged on the side surface of the magnetic gauge stand. The invention also discloses a calibration method of the measuring head pre-stroke of the numerical control machine tool in-situ detection system. The invention solves the problem of low accuracy of pre-stroke detection in the prior art.
Description
Technical Field
The invention belongs to the technical field of numerical control machining precision in-situ detection in a part manufacturing process, and particularly relates to a calibration device for a pre-stroke of a measuring head of a numerical control machine in-situ detection system.
Background
The numerical control machining precision in-situ detection technology of the workpiece omits the transportation of the workpiece between a machine tool and detection equipment, avoids manufacturing errors caused by the misalignment of process references, reduces unnecessary time and material resource consumption, reduces labor intensity, improves productivity, and has great significance for realizing the intellectualization, high efficiency and high precision of the manufacturing process of the product.
Trigger probes are a key component of an in-situ detection system, and a typical structure of a type of probe is shown in fig. 1. When the probe 1 contacts the workpiece during in-situ detection, a trigger signal is generated, and the numerical control system responds to the signal and records the coordinate value of the point. And measuring a plurality of measuring points according to the requirement, and generating a detection report through data processing.
The measuring operation sequence of the measuring head is shown in fig. 2. The contact time of the probe head probe and the measured workpiece is T 1 The moment when the measuring head sends out the trigger signal is T 2 The moment of response of the numerical control system to the trigger signal is T 3 The method comprises the steps of carrying out a first treatment on the surface of the The pre-stroke of the measuring head is T 1 To T 3 And the relative displacement of the measuring head and the measured workpiece in the period. Related researches show that the detection error is caused by the deviation (namely, the pre-stroke) between the measuring point position recorded by the numerical control system and the actual contact position of the probe and the measured workpiece, and the specific gravity in the total error of in-situ detection is up to more than 60%. The compensation is an effective means for reducing the influence of the pre-stroke of the measuring head on the in-situ detection precision, and whether the measurement calibration value of the pre-stroke of the measuring head is accurate or not is a determining factor of the compensation precision.
In general, the directions in which the three-dimensional trigger type probe can be triggered include any direction (radial direction) in the XY plane and +z direction (axial direction). The pre-stroke of the probe is not consistent in different trigger directions under the influence of the structural characteristics of the probe trigger mechanism. The exact compensation should therefore be performed in particular in different directions. The axial pre-stroke of the measuring head is greatly different from the pre-stroke along other directions, and as shown in fig. 3, the axial pre-stroke is measured along the Z direction (axial direction) of the measuring head, and is mostly used for determining the machining allowance and the cutting depth of a workpiece, and the measurement result directly determines the selection of the cutting process parameters of the workpiece and the final machining precision. Therefore, the axial pre-stroke of the probe must be accurately measured before measurement.
At present, for the axial pre-stroke of the measuring head, the method capable of realizing constant value measurement comprises the following two steps: firstly by means of an independent measuring device (hereinafter referred to as independent method). The measuring head is arranged on equipment with motion control, contact state monitoring, trigger signal identification and displacement measurement, the trigger measurement process of the trigger measuring head is simulated, and the pre-stroke of the trigger measuring head is measured. Considering that the pre-stroke of the measuring head can be influenced by the measuring working condition, the measurement should not be independent of the machine tool operating environment. The measurement result of the independent method cannot accurately reflect the pre-stroke of the measuring head during measurement; in addition, the method uses the moment of sending a trigger signal by the measuring head to replace the moment of digitally recording position coordinates during actual measurement as a calculation reference of the pre-stroke, so that the method has principle errors; thirdly, the independent measuring equipment is high in manufacturing cost, complex in operation and poor in engineering adaptability. And secondly, an action radius method. In performing measurement data processing, compensation for probe radius is typically required. Because of the pre-stroke of the measuring head, the compensation is inaccurate by measuring the nominal radius of the ball by the probe in actual measurement. The measuring points are touched and measured on the spherical surface of the standard ball, the measuring radius of the standard ball is calculated, and the difference value between the measuring radius and the nominal radius of the standard ball is the measuring ball action radius of the probe containing the pre-stroke of the measuring head, so that the measuring point is compensated, and the influence of the pre-stroke on the measuring result can be reduced to a certain extent. The action radius method replaces the actual pre-stroke by the equivalent mean value of the pre-stroke in each direction, and the error is homogenized. However, the pre-stroke of the trigger probe in each direction is different, even has a large difference, and the idea of compensating with average error is not suitable for the occasion of measuring along the axial direction, and is difficult to effectively improve the measurement accuracy. It should be pointed out that the standard ball is used as the calibration body, the probe contacts with the standard ball point during measurement and calibration, and is affected by the friction angle of the standard ball point and the standard ball point, and the slip phenomenon inevitably exists between the standard ball point and the standard ball point, so that the measurement point data difference error is caused, and the calibration measurement precision is affected. Meanwhile, the more the number of the measuring points is, the more random error components in the measured data are, and the larger the data fitting error is, so that the number of the measuring points is reduced as much as possible.
Disclosure of Invention
The invention aims to provide a calibration device for a pre-stroke of a measuring head of a numerical control machine tool in-situ detection system, which solves the problem of low pre-stroke detection precision in the prior art.
The invention further aims to provide a calibration method for the pre-stroke of the measuring head of the in-situ detection system of the numerical control machine tool.
The first technical scheme adopted by the invention is that the calibrating device for the pre-stroke of the measuring head of the numerical control machine tool in-situ detection system comprises a trigger measuring head, wherein a probe is arranged at the end part of the trigger measuring head, a regular triangular pyramid is arranged at the vertical corresponding position of the bottom of the probe, the top end of an extension rod is contacted with the bottom of the regular triangular pyramid and fixed with each other, the bottom end of the extension rod is fixed with a magnetic meter seat, and a limit structure is further arranged on the side surface of the magnetic meter seat.
The first aspect of the present invention is also characterized in that,
the extension bar is provided with a waist-shaped through groove parallel to the length direction of the bar, and the set screw passes through the waist-shaped through groove and is screwed into a screw hole on the magnetic meter seat, so that the regular triangular pyramid table and the magnetic meter seat are connected and fixed.
The limit structure comprises the following specific structures: the vertical surface edge of the magnetic meter seat provided with the set screw is fixedly provided with a vertical position stop block and a horizontal position stop block.
The vertical position check block and the horizontal position check block are long cubes and are consistent in orientation, and the vertical position check block and the horizontal position check block are parallel to each other and perpendicular to the magnetic meter seat.
The second technical scheme adopted by the invention is that the calibration method of the pre-stroke of the measuring head of the in-situ detection system of the numerical control machine tool is implemented according to the following steps:
step 1, adsorbing a regular triangular pyramid table on a workbench of a numerical control machine tool through a magnetic meter seat;
step 2, adjusting the positions of an X axis, a Y axis and a Z axis of a machine tool, positioning a probe on a trigger type probe at a certain section of a regular triangular pyramid table, and recording a Z axis coordinate Z at the moment 1 ；
Step 3, keeping the Z axis motionless, linking the X axis and the Y axis, touching 6 points uniformly distributed on three sides on the section to be measured of the regular triangular frustum, namely 2 points on each side, and recording the position coordinates (X i 、Y i ) I= a, b, c, d, e, f, which isA, b, c, d, e, f represents the names of each measuring point on three sides of the measured section;
and 4, respectively calculating linear equations of three sides of the measured section on a series of coordinate values obtained in the step 3 to obtain linear equations of three sides of the measured section regular triangle and three vertex coordinates, and further obtaining the side length L of the measured section, wherein the method comprises the following steps of:
let equation of straight line DF be
y DF ＝K·x+B
Wherein K is the slope of a straight line, B is the intercept of the straight line,
coordinates of the measurement point a (X a 、Y a ) Coordinates of the measurement point b (X b 、Y b ) Carrying out the equation, namely solving the equation of the straight line DF; similarly, the coordinates (X f 、Y f ) Coordinates of the measurement point e (X e 、Y e ) Obtaining an equation of a straight line DE; coordinates of the measurement point d (X d 、Y d ) Coordinates of the measurement point c (X) c 、Y c ) Obtaining an equation of a straight line EF;
the equation of the straight line DF is combined with the equation of the straight line DE and solved to obtain the coordinates (X D 、Y D ) The method comprises the steps of carrying out a first treatment on the surface of the Similarly, the equation of the straight line DE and the equation of the straight line EF are solved simultaneously to obtain the coordinates (X E 、Y E ) The method comprises the steps of carrying out a first treatment on the surface of the Solving the equation of the straight line DF and the equation of the straight line EF simultaneously to obtain the coordinates (X F 、Y F ) According to the formula between two points
Step 5, combining the side length l of the top surface of the regular triangular pyramid and the dihedral angle alpha of the side surface and the bottom surface of the regular triangular pyramid to obtain the theoretical distance delta h between the measured section and the top surface of the triangular pyramid:
step 6, moving the trigger type measuring head upwards along the Z axis so that the trigger type measuring head probe is higher than the regular triangular pyramid table;
step 7, the X-axis and Y-axis interpolation linkage is carried out, and a probe of the trigger type measuring head is positioned right above the top surface of the triangular pyramid table;
step 8, the numerical control machine drives the trigger type measuring head to move downwards along the Z axis to touch any point on the top surface of the regular triangular pyramid table, and the Z axis coordinate Z during triggering is recorded 2 ；
Step 9, combining the theoretical distance delta h between the measured section obtained in the step 5 and the top surface of the frustum, and the Z-axis coordinate Z of the frustum surface obtained in the step 2 1 To obtain the axial pre-stroke tau of the trigger type measuring head,
τ＝△h-[(z 2 -r)-(z 1 +r·cosα)]
wherein r is the radius of the probe sphere, and alpha is the dihedral angle between the side surface and the bottom surface of the regular triangular pyramid;
and after the measurement is finished, taking down the measuring device.
The method has the beneficial effects that 1, the side length of the measured section is calculated by touching 6 measuring points uniformly distributed on three sides on any section of the regular triangular pyramid platform parallel to the bottom surface, so that the theoretical distance between the measured section and the top surface of the regular triangular pyramid platform is obtained; the difference value of the actual measured value between the top surface of the regular triangular pyramid table and the measured section is the axial pre-stroke of the measuring head, so that the in-situ measurement result is compensated and corrected, the influence of the pre-stroke on the measurement precision can be reduced, and the integrated in-situ detection measurement precision is improved. 2. The invention corrects the in-situ detection result based on the measurement calibration result, thereby avoiding measurement errors caused by the difference between the measurement point position of the measurement head touch measurement and the measurement point position recorded by the numerical control system; the error generated by replacing the actual axial pre-stroke with the average value of the pre-stroke of the measuring head in each direction in the existing method is avoided, and the measurement accuracy is improved. 3. According to the method, the pre-stroke of the trigger type measuring head is measured under the actual in-situ detection working condition of the numerical control machine tool, and the result truly reflects the pre-stroke characteristic of the measuring head in the measuring process, so that the measuring precision can be effectively improved. And the regular triangular frustum is used as a measuring tool, other equipment is not needed, the use cost is low, and the operation is simple and convenient. 4. And the trigger type measuring head is adopted for point-by-point measurement, the measuring point data is used as the basis for calculating the measuring result, and the precision of the measuring point data determines the precision of the measuring result. The number of the measurement points influences the measurement efficiency on one hand, and influences the final measurement accuracy on the other hand. From the analysis, the data of the measuring points contain random errors due to the pre-stroke characteristic of the trigger measuring head, the more the number of the measuring points is, the larger the random errors are, and the lower the final measuring precision is; meanwhile, if the standard ball is adopted to calibrate the measuring head, the probe is in point contact with the standard ball, and is influenced by a friction angle, so that slippage is easy to occur between the probe and the standard ball, and deviation exists between actual measuring point data and theoretical data, so that the measuring precision is reduced. The invention only needs to collect two measuring points on each side of the cross section of the triangular pyramid, and the number of the measuring points is greatly reduced. Meanwhile, the contact of the measuring head precalibration body is the contact of points and lines, the friction angle is used for restraining and designing the measuring path and the measuring point position, the generation of measuring point errors caused by the phenomenon of measuring point sliding is greatly avoided, and the precision of the precalibration measuring process can be effectively ensured.
Drawings
FIG. 1 is a schematic view of the basic structure of a trigger gauge head;
FIG. 2 is a timing diagram of trigger gauge head touch operation;
FIG. 3 is a schematic diagram of a numerical control machine tool with a trigger gauge head installed;
FIG. 4 is a schematic diagram of the measurement principle of the trigger type measuring head axial pre-stroke measurement method of the present invention;
FIG. 5 (a) is a schematic diagram of a measuring device of the trigger type measuring head axial pre-stroke measuring method according to the present invention;
fig. 5 (b) is another view of the measuring device of the trigger-type measuring head axial pre-stroke measuring method according to the present invention, and fig. 5 (b) is a left side view of fig. 5 (a);
FIG. 6 is an enlarged detail view of a neutral position stop 7 and a lying position stop 9 of a calibration device for the pre-stroke of a measuring head of the in-situ detection system of the numerical control machine tool;
fig. 7 is a measurement schematic diagram of embodiment 2 of the present invention.
In the figure, 1. Probe; 2. triggering type measuring head; 3. a regular triangular pyramid; 4. a numerical control machine tool workbench; 5. an extension bar; 6. a magnetic gauge stand; 7. a vertical stop block; 8. a set screw; 9. a recumbent position stop block.
Detailed Description
The invention will be described in detail below with reference to the drawings and the detailed description.
The invention relates to a calibrating device for a measuring head pre-stroke of a numerical control machine tool in-situ detection system, which is shown in fig. 1, 3, 5 (a) and 5 (b), and comprises a trigger measuring head 2, wherein a probe 1 is arranged at the end part of the trigger measuring head 2, a regular triangular pyramid 3 is arranged at the vertical corresponding position of the bottom of the probe 1, the top end of a lengthening rod 5 is contacted with the bottom of the regular triangular pyramid 3 and is mutually fixed, the bottom end of the lengthening rod 5 is fixed with a magnetic gauge stand 6, and a limit structure is further arranged on the side surface of the magnetic gauge stand 6.
The extension bar 5 is provided with a waist-shaped through groove parallel to the length direction of the bar, and the set screw 8 passes through the waist-shaped through groove and is screwed in a screw hole on the magnetic gauge stand 6, so that the regular triangular pyramid table 3 and the magnetic gauge stand 6 are connected and fixed.
The limit structure comprises the following specific structures: the vertical surface edge of the magnetic meter seat 6 provided with the set screw 8 is fixed with a vertical position stop block 7 and a horizontal position stop block 9.
The vertical stop block 7 and the horizontal stop block 9 are long cubes and are consistent in orientation, and the vertical stop block 7 and the horizontal stop block 9 are parallel to each other and perpendicular to the magnetic meter seat 6. As shown in fig. 6, the plane ghij on the standing stopper 7 and the plane klmn on the lying stopper 9 are perpendicular to each other. By means of the structure, the positioning of two postures of standing and lying of the regular triangular pyramid can be realized; when the posture of the regular triangular pyramid 3 is adjusted, the tightening nut 8 is loosened, the regular triangular pyramid 3 and the extension rod 5 which are connected together in a rotating way around the axis of the tightening nut 8 are screwed down, and when the side wall of the extension rod 5 is in contact with the plane ghij on the vertical stop block 7, the tightening nut 8 is screwed down, and the vertical installation posture is realized at the moment; if the extension bar 5 is rotated around the axis of the tightening nut 8, the tightening nut 8 is tightened when the side wall thereof is in contact with the plane klmn on the lying stop 9, which is now in the lying mounting position. Fig. 6 is a measurement schematic diagram of embodiment 2 of the present invention, wherein the thin dotted line represents the section and path measured by the probe, and the dotted line represents the path of the probe when the position of the top surface of the regular triangular pyramid table is touched after the section is measured. When the measurement is calibrated, the regular triangular pyramid is reliably arranged at the top end of the extension bar 5, and the bottom surface of the regular triangular pyramid is vertical to the axis of the extension bar; loosening the set screw 8, adjusting the angle position of the extension rod 5 according to the gesture of the measuring head to be calibrated, and locking the set screw 8 after accurate positioning; and finally, the whole device is adsorbed at a proper position of the workbench 4 of the numerical control machine tool, and measurement and calibration can be started.
The calibration method of the measuring head pre-stroke of the numerical control machine tool in-situ detection system is implemented according to the following steps:
step 1, adsorbing a regular triangular pyramid table 3 on a workbench 4 of a numerical control machine tool through a magnetic meter seat 6;
step 2, adjusting the positions of an X axis, a Y axis and a Z axis of a machine tool, positioning a probe 1 on a trigger type measuring head 2 at a certain section of a regular triangular pyramid table 3, and recording a Z axis coordinate Z at the moment 1 ；
Step 3, keeping the Z axis motionless, linking the X axis and the Y axis, touching 6 points uniformly distributed on three sides, namely 2 points on each side on the section to be measured of the regular triangular pyramid table 3, and recording the position coordinates (X i 、Y i ) I= a, b, c, d, e, f, wherein a, b, c, d, e, f represents the name of each measuring point on three sides of the measured section;
and 4, respectively calculating linear equations of three sides of the measured section on the series of coordinate values obtained in the step 3 to obtain linear equations of three sides of the measured section regular triangle and three vertex coordinates, and further obtaining the side length L of the measured section, wherein the method comprises the following steps of:
let equation of straight line DF be
y DF ＝K·x+B
Wherein K is the slope of a straight line, B is the intercept of the straight line,
coordinates of the measurement point a (X a 、Y a ) Coordinates of the measurement point b (X b 、Y b ) Carrying out the equation, namely solving the equation of the straight line DF; similarly, the coordinates (X f 、Y f ) Coordinates of the measurement point e (X e 、Y e ) Obtaining an equation of a straight line DE; coordinates of the measurement point d (X d 、Y d ) Coordinates of the measurement point c (X) c 、Y c ) Obtaining an equation of a straight line EF;
the equation of the straight line DF is combined with the equation of the straight line DE and solved to obtain the coordinates (X D 、Y D ) The method comprises the steps of carrying out a first treatment on the surface of the Similarly, the equation of the straight line DE and the equation of the straight line EF are solved simultaneously to obtain the coordinates (X E 、Y E ) The method comprises the steps of carrying out a first treatment on the surface of the Solving the equation of the straight line DF and the equation of the straight line EF simultaneously to obtain the coordinates (X F 、Y F ) According to the formula between two points
Step 5, combining the side length l of the top surface of the regular triangular pyramid and the dihedral angle alpha of the side surface and the bottom surface of the regular triangular pyramid to obtain the theoretical distance delta h between the measured section and the top surface of the triangular pyramid:
step 6, moving the trigger type measuring head upwards along the Z axis so that the trigger type measuring head probe is higher than the regular triangular pyramid table;
step 7, the X-axis and Y-axis interpolation linkage is carried out, and the probe 1 of the trigger type measuring head 2 is positioned right above the top surface of the triangular pyramid table;
step 8, the numerical control machine drives the trigger type measuring head 2 to move downwards along the Z axis to touch any point on the top surface of the regular triangular pyramid table, and the Z axis coordinate Z during triggering is recorded 2 ；
Step 9, combining the theoretical distance delta h between the measured section obtained in the step 5 and the top surface of the frustum, and the Z-axis coordinate Z of the frustum surface obtained in the step 2 1 To obtain the axial pre-stroke tau of the trigger type measuring head,
τ＝△h-[(z 2 -r)-(z 1 +r·cosα)]
wherein r is the radius of the probe sphere, and alpha is the dihedral angle between the side surface and the bottom surface of the regular triangular pyramid;
and after the measurement is finished, taking down the measuring device.
The triggering type measuring head pre-stroke (axial direction) measuring method adopts a regular triangular pyramid table as a measuring tool, and is shown in fig. 3, 4, 5 and 6. The principle is that the distance delta h between any section and the top surface on the regular triangular pyramid can be determined by the side length of the section, the side length of the top surface and the dihedral angle between the side surface and the bottom surface of the regular triangular pyramid. 6 points uniformly distributed along the circumference are touched and measured on a certain section of the regular triangular pyramid table, and linear fitting operation is carried out on coordinate values of all measuring points to obtain the side length of the measured section; then measuring the distance between the measured section and the top surface of the regular triangular pyramid table; finally, the influence of the probe radius of the measuring head on the measuring result is synthesized, and the pre-stroke (axial direction) of the triggering measuring head is as follows:
τ＝△h-[(z 2 -r)-(z 1 +r·cosα)]
wherein r is the radius of the probe sphere, alpha is the dihedral angle between the side surface and the bottom surface of the regular triangular pyramid, Z 2 The Z-axis position coordinate corresponding to the top surface of the regular triangular pyramid; z is Z 1 And the Δh is the theoretical distance between the measured section and the top surface of the frustum for the Z-axis position coordinate corresponding to the measured section.
And after the measurement is finished, taking down the measuring device.
Example 1
This example measures the axial pre-travel of a Raney Shaoxing LP2 trigger gauge head. The measuring head is arranged on a numerical control machine tool shown in fig. 3 in a vertical posture, and the axial direction of the measuring head is the Z direction of the numerical control machine tool.
The surfaces of the regular triangular pyramid and the probe of the measuring head are cleaned, and the measuring device is adsorbed at the proper position of the workbench 4 of the numerical control machine tool, so that the measuring device is ensured to be in the working stroke of the triggering type measuring head 2 in all directions; the touch measurement of a certain section of the regular triangular pyramid platform is completed, and the position coordinates of each measuring point are recorded; calculating the lengths of three sides of the measured section; under the control of NC program, measuring the distance between the measured section and the top surface of the regular triangular pyramid; and finally, calculating the axial pre-stroke of the measuring head.
Comparison of experimental results
The measurement results of the measurement calibration method using the present invention and the measurement results of the measurement using the radius of action method are shown in table 1 below,
table 1 axial pre-travel for different measurement methods
Comparison shows that the pre-stroke obtained by the radius of action method is larger than that obtained by the method. Because the radial pre-stroke of the measuring head is larger than the pre-stroke during axial triggering, the axial pre-stroke measured value can be influenced by the pre-stroke in other directions by adopting the action radius method of the homogenization error idea, and the obtained result has larger error. Experiments show that the in-situ detection precision can be influenced by taking the compensation value as the compensation value of the pre-stroke. According to the results in the related literature, when the measuring head of the same type as the example is measured by adopting the independent equipment method, the axial pre-stroke is about 0.002mm, which is far smaller than the result obtained by the method, because the independent equipment method enables the measurement of the measuring head to be independent of the measurement working condition of the measuring head, and the moment of the numerical control recording position coordinates when the measuring head sends out a trigger signal is used as the accounting reference of the pre-stroke instead of the moment of the numerical control recording position coordinates when the measuring head is actually measured, so that the measurement result cannot reflect the real condition of the pre-stroke of the measuring head during the measurement and is not suitable for the on-site compensation of the pre-stroke of the triggering measuring head.
Example 2
Referring to fig. 7, the measuring head is horizontally installed, and the axial direction is the X direction of the numerical control machine tool.
Firstly, loosening a set screw 8, rotating a regular triangular pyramid table by 90 degrees around the axis of the set screw, enabling an extension rod to be in contact with a horizontal pose stop block 9, screwing the set screw 8 after the extension rod is in place, and adsorbing the set screw 8 at a proper position of a machine tool workbench to ensure that the set screw is in each movement stroke of a trigger type measuring head 2;
then controlling each axis of the machine tool to move, positioning the trigger type measuring head probe at the section of the regular triangular pyramid table, performing test touch measurement, and recording X-axis coordinate X during triggering 1 (the position shown by the thin dashed line in fig. 7);
six points (2 measuring points on each side of the section) which are uniformly distributed are touched on the section to be measured through Z, Y axis interpolation movement, and the position coordinate (Z i 、Y i )；
Fitting calculation is carried out on the obtained series of coordinate values to obtain a linear equation and vertex coordinates of three sides of the measured section, and the section side length L is finally calculated;
adjusting each axis of the machine tool to enable the probe of the measuring head to be far away from the regular triangular pyramid in the X direction;
positioning the measuring head in the range of the top surface of the frustum through Z, Y axis interpolation motion;
the X-axis carries out touch measurement on the vertex of the regular triangular pyramid table, and the coordinate X of the X-axis when the measuring head is triggered is recorded 2 。
And (3) data processing: according to the obtained X-direction coordinate X of the measured section 1 The side length L of the measured section and the X-direction coordinate X of the top surface of the frustum 2 According to the trigger type measuring head axial pre-stroke calculation formula provided by the method, the pre-stroke (axial direction) of the measuring head is calculated;
and after the measurement is finished, taking down the measuring tool, and filling the calculated pre-stroke of the measuring head into an in-situ detection data processing software compensation table.
Claims (5)
1. The calibrating device of digit control machine tool normal position detecting system gauge head advance stroke, its characterized in that, including trigger gauge head (2), trigger gauge head (2) tip is equipped with probe (1), and vertical corresponding position department in probe (1) bottom is provided with regular triangular pyramid platform (3), and extension bar (5) top contacts and mutually fixes with regular triangular pyramid platform (3) bottom, and extension bar (5) bottom is fixed with magnetic gauge stand (6), and magnetic gauge stand (6) side still is provided with limit structure.
2. The calibrating device for the pre-stroke of the measuring head of the numerical control machine tool in-situ detection system according to claim 1, wherein the extension rod (5) is provided with a waist-shaped through groove parallel to the length direction of the rod, and the fastening screw (8) passes through the waist-shaped through groove and is screwed in a screw hole on the magnetic gauge stand (6), so that the regular triangular pyramid table (3) is fixedly connected with the magnetic gauge stand (6).
3. The calibrating device for the pre-stroke of the measuring head of the in-situ detection system of the numerical control machine tool according to claim 2, wherein the limiting structure is specifically structured as follows: the vertical surface edge of the magnetic meter seat (6) is provided with a set screw (8) and is fixedly provided with a vertical position stop block (7) and a horizontal position stop block (9).
4. The calibrating device for the pre-stroke of the measuring head of the numerical control machine tool in-situ detection system according to claim 3, wherein the vertical stop block (7) and the horizontal stop block (9) are long cubes and are consistent in orientation, and the vertical stop block (7) and the horizontal stop block (9) are parallel to each other and are perpendicular to the magnetic meter base (6).
5. The calibration method of the pre-stroke of the measuring head of the in-situ detection system of the numerical control machine tool is characterized by being based on the calibration device of the pre-stroke of the measuring head of the in-situ detection system of the numerical control machine tool, which is specifically implemented according to the following steps:
step 1, adsorbing a regular triangular pyramid table (3) on a workbench (4) of a numerical control machine tool through a magnetic meter seat (6);
step 2, adjusting the positions of an X axis, a Y axis and a Z axis of a machine tool, positioning a probe (1) on a trigger type measuring head (2) at a certain section of a regular triangular pyramid table (3), and recording a Z axis coordinate Z at the moment 1 ；
Step 3, keeping the Z axis motionless, linking the X axis and the Y axis, touching 6 points uniformly distributed on three sides on the section to be measured of the regular triangular pyramid table (3), namely 2 points on each side, and recording the position coordinates (X i 、Y i ) I= a, b, c, d, e, f, wherein a, b, c, d, e, f represents the name of each measuring point on three sides of the measured section;
and 4, respectively calculating linear equations of three sides of the measured section on the series of coordinate values obtained in the step 3 to obtain linear equations of three sides of the measured section regular triangle and three vertex coordinates, and further obtaining the side length L of the measured section, wherein the method comprises the following steps of:
let equation of straight line DF be
y DF ＝K·x+B
Wherein K is the slope of a straight line, B is the intercept of the straight line,
coordinates of the measurement point a (X a 、Y a ) Coordinates of the measurement point b (X b 、Y b ) Carrying out the equation, namely solving the equation of the straight line DF; similarly, the coordinates (X f 、Y f ) Measuring point eCoordinates (X) e 、Y e ) Obtaining an equation of a straight line DE; coordinates of the measurement point d (X d 、Y d ) Coordinates of the measurement point c (X) c 、Y c ) Obtaining an equation of a straight line EF;
the equation of the straight line DF is combined with the equation of the straight line DE and solved to obtain the coordinates (X D 、Y D ) The method comprises the steps of carrying out a first treatment on the surface of the Similarly, the equation of the straight line DE and the equation of the straight line EF are solved simultaneously to obtain the coordinates (X E 、Y E ) The method comprises the steps of carrying out a first treatment on the surface of the Solving the equation of the straight line DF and the equation of the straight line EF simultaneously to obtain the coordinates (X F 、Y F ) According to the formula between two points
Step 5, combining the side length l of the top surface of the regular triangular pyramid and the dihedral angle alpha of the side surface and the bottom surface of the regular triangular pyramid to obtain the theoretical distance delta h between the measured section and the top surface of the triangular pyramid:
step 6, moving the trigger type measuring head upwards along the Z axis so that the trigger type measuring head probe is higher than the regular triangular pyramid table;
step 7, the X-axis and Y-axis interpolation linkage is carried out, and a probe (1) of the trigger type measuring head (2) is positioned right above the top surface of the triangular pyramid table;
step 8, the numerical control machine drives the trigger type measuring head (2) to move downwards along the Z axis to touch and measure any point on the top surface of the regular triangular pyramid table, and the Z axis coordinate Z during triggering is recorded 2 ；
Step 9, combining the theoretical distance delta h between the measured section obtained in the step 5 and the top surface of the frustum, and the Z-axis coordinate Z of the frustum surface obtained in the step 2 1 To obtain the axial pre-stroke tau of the trigger type measuring head,
τ＝△h-[(z 2 -r)-(z 1 +r·cosα)]
wherein r is the radius of the probe sphere, and alpha is the dihedral angle between the side surface and the bottom surface of the regular triangular pyramid;
and after the measurement is finished, taking down the measuring device.
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