JP2015222196A - Three dimensional measuring machine and method for measuring shape using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three dimensional measuring machine capable of using the same part program without requiring a highly accurate jig even when how to place an object to be measured is changed, and a method for measuring a shape using the three dimensional measuring machine.SOLUTION: A three dimensional measuring machine 10 having a probe head 24 simultaneously controlling five axes includes a computer 32 having a software programs 32a and control means 40, and a drive controller 28. The control means 40 comprises: a CPU42, storage means 44, part program preparation means 46, part program execution means 48, setting means 50, correction value acquisition means 52, instruction means 54 and coordinate transformation means 56. A method for measuring a shape using three dimensional measuring machine comprises: setting a new original point and new reference XYZ axes to an object W2 to be measured; obtaining posture correction values in a vertical direction and a horizontal direction; and correcting a position of the probe head 24 on the basis of the posture correction value to measure the shape of the object W2 to be measured.

Description

  The present invention relates to a three-dimensional measuring machine and a shape measuring method using the same.

  Conventionally, a probe head having first driving means (for example, a motor) for rotating the probe around two rotation axes orthogonal to each other, and second driving means for moving the probe head in three axial directions orthogonal to each other (for example, A three-dimensional measuring machine having a so-called 5-axis probe head provided with a motor is known (for example, see Patent Document 1).

  In the three-dimensional measuring machine described in Patent Document 1, the probe head moves based on a part-programmed measurement path, whereby an object to be measured (also referred to as a workpiece) is automatically measured.

JP 2010-537184 A

  In general, in a coordinate measuring machine having a five-axis probe head, posture information of the probe head when measuring an object to be measured is written in a part program. When measuring the object to be measured, a part program is read, and the attitude of the probe head is controlled based on the attitude information.

  However, the posture information of the probe head written in the part program is described on the assumption that the object to be measured is accurately placed on the table. A highly accurate jig is required for placing the object to be measured. Therefore, if a high-precision jig cannot be prepared, the object to be measured is placed in an incorrect state, and there is a problem that the object to be measured cannot be measured accurately.

  In addition, there is a demand for measuring another object to be measured using a part program that has already been created. In that case, it may be necessary to place the measurement object in an inclined state due to the size of the coordinate measuring machine. Also in this case, it is determined that the object to be measured is in an incorrect arrangement state, and there is a problem that the already created part program cannot be used.

  The present invention has been made in view of such circumstances, and does not require a highly accurate jig, and even if the method of placing the object to be measured is changed, the same part program can be used. The purpose is to reduce the cost burden on the operator and improve productivity.

  A three-dimensional measuring machine according to an aspect of the present invention moves a probe head having first driving means for rotating a probe around two rotation axes orthogonal to each other, and the probe head in three axial directions orthogonal to each other. A second drive unit; a table on which an object to be measured is placed; a drive controller that drives the first drive unit and the second drive unit; and a control unit that controls the drive controller. The storage means for storing the part program in which the posture information of the probe head is described in the work coordinate system in which the origin is set and the XYZ reference axis is set, and the arrangement state of the object to be measured placed on the table is detected Setting means for determining a new reference Z-axis for the object to be measured and then determining a new reference XY-axis to set a new reference XYZ axis and a new origin Correction value acquisition means for obtaining posture correction values of the probe head in the vertical direction and the horizontal direction from the new origin and the new reference XYZ axis and the origin and the reference XYZ axis, and the probe head based on the posture correction value And an instruction means for instructing the drive controller to execute the part program by converting the posture information of the probe head from a work coordinate system to a machine coordinate system.

  Preferably, the setting means for setting a new reference XYZ reference axis and a new origin determines the new reference Z-axis by measuring at least three points on the plane of the object to be measured by the probe head, and the object to be measured Measuring at least two points on the side surface of the first reference XY axis.

  According to another aspect of the present invention, a shape measuring method using a coordinate measuring machine includes a probe head having first driving means for rotating a probe around two rotation axes orthogonal to each other, and the probe head orthogonal to each other. Second driving means for moving in the three-axis directions, a table for placing an object to be measured, a drive controller for driving the first driving means and the second driving means, and control means for controlling the drive controller , Wherein the control means stores a part program in which the posture information of the probe head is described in a work coordinate system with an origin setting and a reference XYZ axis setting. Detecting an arrangement state of the object to be measured placed on the table and determining a new reference Z axis for the object to be measured, and then a new reference XY axis A step of determining and setting a new reference XYZ axis and a new origin, and vertical and horizontal postures of the probe head from the new origin and the new reference XYZ axis and the origin and the reference XYZ reference axis Obtaining a correction value; reading the part program; correcting the posture of the probe head based on the posture correction value; and converting the posture information of the probe head from a work coordinate system to a machine coordinate system; And instructing to.

  Preferably, the step of setting a new reference XYZ reference axis and a new origin is performed by measuring at least three points on the plane of the object to be measured by the probe head and determining the new reference Z axis; Measuring at least two points on the side of the object to determine the new reference XY axis.

  According to the present invention, a highly accurate jig is not required, and even if the object to be measured is changed, the same part program can be used, reducing the cost burden on the operator and improving the productivity. Can be made.

It is a perspective view of a three-dimensional measuring machine. It is an enlarged view of a probe head. It is a block diagram which shows the structural example of a three-dimensional measuring machine. It is a flowchart for demonstrating operation | movement of a coordinate measuring machine. It is a perspective view which shows the state which is performing the part program process in a coordinate measuring machine. It is explanatory drawing for demonstrating a machine coordinate system origin. It is a perspective view which shows the state which set the origin and the reference | standard XYZ axis to the to-be-measured object. It is a perspective view which shows the state which is performing the process which measures the new reference | standard Z axis | shaft of the upper surface of a to-be-measured object. It is a perspective view which shows the state which set the new reference | standard Z axis | shaft to the to-be-measured object. It is a perspective view which shows the state which set the new reference | standard XY axis to the to-be-measured object. It is a perspective view which shows the state which set the new origin and the new reference | standard XYZ axis | shaft to the to-be-measured object.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. Here, in the drawing, portions indicated by the same symbols are similar elements having similar functions.

  Preferred embodiments of a shape measuring method using a coordinate measuring machine according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a coordinate measuring machine 10 according to the present embodiment. The coordinate measuring machine 10 (CMM: Coordinating Measuring Machine) is a device that moves the probe head 24 and determines the spatial coordinates on the surface of the object to be measured (also called a workpiece). Also called a machine. In the present embodiment, a portal moving type coordinate measuring machine 10 will be described as an example.

  As shown in FIG. 1, the coordinate measuring machine 10 includes a gantry 12, a table 14 (surface plate) on which the gantry 12 is placed, a right Y carriage 16 </ b> R and a left Y carriage that are erected on both sides of the table 14. 16L, and an X guide 18 for connecting the upper portions of the right Y carriage 16R and the left Y carriage 16L. A portal frame 26 is configured by the right Y carriage 16R, the left Y carriage 16L, and the X guide 18.

  A sliding surface is formed in the Y-axis direction on the upper surface and the side surfaces of both sides of the table 14, and air bearings are provided in the right Y carriage 16R and the left Y carriage 16L. The 16R and the left Y carriage 16L are movable together with the X guide 18 in the Y-axis direction.

  The X guide 18 is provided with a sliding surface in the X-axis direction, and an X carriage 20 incorporating an air bearing is provided so as to be movable in the X-axis direction. The X carriage 20 incorporates an air bearing for guiding in the Z-axis direction. A Z spindle 22 is provided so as to be movable in the Z axis direction along an air bearing for guiding in the Z axis direction.

  A probe head 24 is attached to the lower end of the Z spindle 22. The probe head 24 is a probe head (5-axis simultaneous control probe head) provided with a stepless positioning mechanism, and the probe 24a (stylus 24b) of the contact-type touch trigger has two rotation axes A or B orthogonal to each other (FIG. 1). 1st drive means (for example, a motor. It does not show in figure) rotated around a reference. According to the probe head 24, faster measurement (probing, that is, an operation for determining coordinate values) can be performed by using only the rotation operation around the rotation axis A or B.

  The coordinate measuring machine 10 includes second driving means (for example, a motor, not shown) that moves the probe head 24 in three axial directions (XYZ directions) orthogonal to each other. By moving the portal frame 26, the X carriage 20 and the Z spindle 22 in the respective axial directions by the second driving means, the probe head 24 can be moved in three axial directions (XYZ directions) orthogonal to each other.

  Scales are provided in the Y-axis direction of the table 14, the X guide 18, and the Z spindle 22. A detection head in the Y-axis direction is attached to the right Y carriage 16R, and a detection head in the X-axis direction and the Z-axis direction is attached to the X carriage 20, so that the contact 24c at the tip of the probe 24a (stylus 24b) is covered. At the moment of contact with the workpiece (workpiece), the three-dimensional coordinate position is detected.

  A drive controller 28 that controls the movement of the coordinate measuring machine 10 and the probe head 24 is connected to the coordinate measuring machine 10. A computer 32 is connected to the drive controller 28 via a communication interface 30 such as a LAN (TCP / IP). A joystick (not shown) for remotely controlling the movement of the probe head 24 is connected to the drive controller 28. The joystick is provided in an operation box (not shown).

  The computer 32 executes a software program 32a (including software for confirming the measurement operation and confirming the measurement result) installed therein, and a measurement path (both the part program and the target program) including coordinate values of target points and intermediate points. And the first driving means and / or the second driving means are controlled (CNC control) based on the measurement path, and the probe head 24 is automatically moved. Then, the object to be measured is automatically measured.

  FIG. 2 is an enlarged view of the probe head 24. The probe head 24 is connected to the Z spindle 22. As shown in FIG. 2A, the probe 24a (stylus 24b (contact 24c)) is moved steplessly within a range of a vertical angle ± θ with respect to the rotation axis A (axis perpendicular to the paper surface). be able to. The position of the lowest point of the tip of the stylus 24b can be set to 0 °, and can be rotated about the rotation axis A from, for example, an elevation angle of −115 ° (−θ) to an elevation angle of +115 (+ θ).

  Further, as shown in FIG. 2B, the probe 24a (stylus 24b) can be rotated steplessly around the rotation axis B within a horizontal angle ± φ. The horizontal angle ± φ is ± 180 ° and can be freely rotated.

  FIG. 3 is a block diagram illustrating a configuration example of the coordinate measuring machine 10. The computer 32 includes a software program 32a and a control means 40. The control unit 40 includes a CPU 42, a storage unit 44, a part program creation unit 46, a part program execution unit 48, a setting unit 50, a correction value acquisition unit 52, an instruction unit 54, and a coordinate conversion unit 56. I have.

  Next, the operation of the coordinate measuring machine 10 configured as described above will be described with reference to FIGS. FIG. 4 is a flowchart for explaining the operation of the coordinate measuring machine 10.

  First, the workpiece W1 is placed on the table (step S10).

  While moving the probe head 24 by the drive controller 28, the probe head 24 is brought into contact with the object to be measured W1. The posture information of the probe head 24 when actually measuring the workpiece W1 (measurement path including coordinate values of target points and intermediate points) is obtained as coordinate values based on the machine coordinate system (step S12). For example, as shown in FIG. 5, the contact information 24c of the probe head 24 is brought into contact with the object W1 to obtain posture information of the probe head 24. Here, the mechanical coordinate system means a coordinate that is unique to the coordinate measuring machine 10 and mechanically determined, and means a coordinate system that is determined based on the origin of the mechanical coordinate system unique to the coordinate measuring machine 10. To do. The probe head 24 moves on the table 14 based on the coordinate values of this machine coordinate system. As shown in FIG. 6, the machine coordinate system origin is generally set at the upper left rear or the lower left front of the measurement range.

  Next, the obtained posture information of the probe head 24 is converted into a workpiece coordinate system based on the workpiece W1. The posture information converted into the work coordinate system is described in the part program, and the part program is stored (step S14).

  The part program creating means 46 creates a part program in response to an instruction from the CPU 42. The work coordinate system means a coordinate system set on the workpiece W1 with the workpiece W1 as a reference. As shown in FIG. 7, in the work coordinates, the setting of the origin (origin O) with respect to the workpiece W1 and the setting of the reference XYZ axes are executed. At this time, if the origin O set on the workpiece W1 does not match, the offset amount between the machine coordinate system origin Om and the origin O is stored. The setting unit 50 executes the origin and the reference XYZ axes with respect to the workpiece W1. In the part program, the measurement position of the workpiece W1, the intermediate point, the moving direction (approach direction) to the measurement position, the posture of the probe head 24, and the like are described as coordinate values in the workpiece coordinate system. The coordinate conversion means 56 converts the coordinate value from the machine coordinate system to the workpiece coordinate system in accordance with a command from the CPU 42. In the part program, for example, commands are described in the format of X (), Y (), Z (): I (), J (), K (): A (), B (). X (), Y (), and Z () indicate measurement positions at which the contact 24c comes into contact with the object to be measured W1. In addition, I (), J (), and K () indicate the movement direction (approach direction) to the measurement position. A () and B () indicate the vertical angle θ and the horizontal angle φ of the probe head 24. That is, A () and B () indicate the posture of the probe head 24. The created part program is stored in the storage means 44.

  Next, when the part program described in the workpiece coordinate system is stored, the process proceeds to the step of measuring the workpiece W2 to be measured. The object to be measured W2 to be measured is placed on the table 14 (step S16).

  Next, the arrangement state of the workpiece W2 placed on the table 14 is detected, the inclination of the upper surface of the workpiece W2 is obtained, and a new reference Z-axis is determined (step S18). For example, as shown in FIG. 8, the posture of the probe head 24 is changed so that the probe 24a, the stylus 24b, and the contactor 24c are parallel to the Z axis and the contactor 24c has a vertical angle of 0 °. In this state, the contact 24c is brought into contact with the upper surface of the workpiece W2 three times. A plane is determined based on the three measured points, and then a new reference Z-axis is determined based on the plane. The angle difference between the reference Z-axis of the reference XYZ axis and the new reference Z-axis of the workpiece coordinate system set in the part program is obtained. That is, the posture correction value in the vertical direction is obtained.

  For example, as a result of the measurement, when the X axis is rotated by 5 ° around the Y axis (when the new reference Z axis is inclined by 5 ° with respect to the reference Z axis), as shown in FIG. The new reference Z-axis is required to be inclined, for example, 5 ° with respect to the reference Z-axis.

  This can be expressed as follows by a transformation matrix. First, when the workpiece coordinate system is not set for the object to be measured, the transformation matrix is as shown in Equation (1).

  When the upper surface of the workpiece W2 is measured, the normal vector of the upper surface is obtained. When the new reference Z-axis is inclined by 5 ° with respect to the reference Z-axis, based on this normal vector, the conversion matrix between the new reference Z-axis and the X axis / Y axis orthogonal to the new reference Z axis is: The formula (1) is updated to the formula (2).

  After obtaining the new reference Z-axis, the new reference XY-axis of the workpiece W2 is obtained (step S20). For example, as shown in FIG. 10, the posture of the probe head 24 is changed so that the probe 24a, the stylus 24b, and the contactor 24c are parallel to the Z axis and the contactor 24c has a vertical angle of 0 °. In this state, the contact 24c is brought into contact with the side surface of the workpiece W2 twice. A straight line is determined based on the two measured points, and then a new reference X-axis and a new reference Y-axis orthogonal to the new reference X-axis are determined based on the straight line. A new reference XY axis is determined. In the case of equation (2), there is no change in the Y axis.

  The angle difference between the reference X axis of the reference XYZ axes of the workpiece coordinate system set in the part program and the new reference X axis is obtained. That is, the horizontal posture correction value is obtained. Similarly, the angle difference between the reference Y axis of the reference XYZ axis and the new reference Y axis is obtained. The new reference X-axis is inclined, for example, 5 ° with respect to the reference X-axis of the reference XYZ reference axis, and the new reference Y-axis is inclined, for example, 5 ° with respect to the reference Y-axis of the reference XYZ reference axis. Is required. Regarding the determination of the new reference XY axis, the new reference X axis is obtained in the order of the new reference Y axis, but may be obtained in the order of the new reference Y axis and the new reference X axis.

  When the new reference X axis is rotated by 5 ° with respect to the reference X axis on the XY plane, the conversion matrix of the new reference X axis and the new reference Y axis is updated from Equation (2) to Equation (3). .

  After the new reference XYZ axes are determined, a new origin is set for the workpiece W2 (step S22). For example, as shown in FIG. 11, a new origin and a new reference XYZ axis are set for the workpiece W2. The new origin and the new reference XYZ axes are set by the setting means 50 in accordance with a command from the CPU 42.

  Next, after the new origin O and the new reference XYZ axis are set, the posture correction values of the probe head 24 in the vertical and horizontal directions are obtained from the new origin O, the new reference XYZ axis, the origin O, and the reference XYZ axis. . For example, a transformation matrix is obtained by Expression (3). Also, an offset amount between the new origin and the origin is obtained. The conversion matrix and the offset amount are acquired as the posture correction value of the probe head 24. The posture correction value is acquired by the correction value acquisition means 52 according to a command from the CPU 42 (step S24).

  Next, the posture of the probe head 24 is corrected based on the posture correction value, the posture information of the probe head is converted into the machine coordinate system, the part program is executed, and an instruction is given to the drive controller 28 (step S26).

  In order for the drive controller 28 to control the probe head 24, coordinate values in the machine coordinate system are required. In the part program, the posture information of the probe head 24 is described in the work coordinate system. Therefore, the posture information (coordinate values) of the probe head 24 is converted from the workpiece coordinate system to the machine coordinate system. At this time, the posture correction value is added as the value of the machine coordinate system to the posture information (coordinate value) of the probe head 24 converted into the machine coordinate system, and the part program is read by the command of the CPU 42, and the part program execution means 48. Note that the conversion from the workpiece coordinate system to the machine coordinate system is executed by the coordinate conversion means 56 in accordance with a command from the CPU 42.

  Next, measurement of the workpiece W2 is performed (step S28). The drive controller 28 controls the movement and measurement of the probe head 24 based on the instruction of the part program. The instruction based on the part program is transmitted to the drive controller 28 by the instruction means 54. Measurement values from the probe head 24 are transmitted to the computer 32. The measurement result is displayed and stored on the computer 32.

  Next, it is determined whether or not all the objects to be measured W2 have been measured (step S30). While it is determined No in step S30, the processing from step S16 to step S28 is repeated. If it is determined as Yes in step S30, the measurement of the workpiece W2 is terminated.

  In the present embodiment, it is preferable to perform the following steps in consideration of the direction of the XYZ axes of the machine coordinate system and the case where the machine coordinate system is not parallel to the surface plate surface.

  In step S12 and step S14, the surface plate surface is measured by the probe head. Check the Z direction and X, Y direction, and determine the X, Y, Z coordinates with reference to the surface plate. Based on the design data input to the device in advance, the upper surface normal of the workpiece (reference surface having the normal direction of the Z axis) is measured and set at three points. The normal line of the probe head is aligned with the work direction by using a drive mechanism with a vertical angle θ and a horizontal angle φ. Performs vector conversion of surface plate normal and workpiece normal.

  Next, the X axis and the Y axis are measured, and a deviation in the workpiece direction between the X direction and the Y direction is detected in comparison with the surface of the surface plate. Finally, the deviations in the Z direction, X, and Y directions are calculated, and conversion of the work coordinate system is set based on the surface plate coordinate system.

  Here, the machine coordinate system does not necessarily coincide with the surface plate coordinate system. This is because the machine coordinate system is based on the direction of the slide mechanism of the column, but the surface plate and the slide mechanism are not necessarily parallel. In this embodiment, the direction of the slide mechanism is not used as a reference, but the surface plate surface is used as a reference. Usually, since the object to be measured (work) is placed on the surface plate and measured, the bottom surface of the object to be measured (work) coincides with the surface of the surface plate. Accordingly, the normal direction of the upper surface of the object to be measured is set with reference to the bottom surface of the object to be measured, so that accurate measurement can be performed. That is, it is possible to measure more accurately by converting the value written in the part program into the work coordinate system using the orientation of the surface plate as the reference of the machine coordinate system.

  The above embodiment is merely an example in all respects. The present invention is not construed as being limited to these descriptions. The present invention can be implemented in various other forms without departing from the technical idea or main features thereof.

  DESCRIPTION OF SYMBOLS 10 ... Three-dimensional measuring machine, 12 ... Stand, 14 ... Table, 16L, 16R ... Y carriage, 18 ... X guide, 20 ... X carriage, 22 ... Spindle, 24 ... Probe head, 24a ... Probe, 24b ... Stylus, 24c DESCRIPTION OF SYMBOLS Contact, 26 ... Portal frame, 28 ... Controller, 30 ... Communication interface, 32 ... Computer, 32a ... Software program, 40 ... Control means, 42 ... CPU, 44 ... Storage means, 46 ... Part program creation means, 48 ... part program execution means, 50 ... setting means, 52 ... correction value acquisition means, 54 ... instruction means, 56 ... coordinate conversion means, W1, W2 ... measurement object

Claims (4)

A probe head comprising first driving means for rotating the probe around two rotation axes orthogonal to each other;
Second driving means for moving the probe head in three axial directions orthogonal to each other;
A table on which the object to be measured is placed;
A drive controller for controlling the first drive means and the second drive means;
Control means for controlling the drive controller, and a coordinate measuring machine comprising:
The control means includes
Storage means for storing a part program in which the posture information of the probe head is described in the workpiece coordinate system in which the origin and the reference XYZ axes are set;
The arrangement state of the object to be measured placed on the table is detected, a new reference Z axis is determined for the object to be measured, and then a new reference XY axis is determined to set a new reference XYZ axis And a setting means for setting a new origin,
Correction value acquisition means for obtaining posture correction values of the probe head in the vertical direction and the horizontal direction from the new origin and the new reference XYZ axis and the origin and the reference XYZ axis;
Instruction means for correcting the attitude of the probe head based on the attitude correction value, converting the attitude information of the probe head from a work coordinate system to a machine coordinate system, executing the part program, and instructing the drive controller; ,
CMM equipped with.   The setting means for setting a new reference XYZ axis and a new origin determines at least three points on the plane of the object to be measured by the probe head to determine the new reference Z axis, The coordinate measuring machine according to claim 1, comprising measuring at least two points on a side surface to determine the new reference XY axis. A probe head comprising first driving means for rotating the probe around two rotation axes orthogonal to each other;
Second driving means for moving the probe head in three axial directions orthogonal to each other;
A table on which the object to be measured is placed;
A drive controller for controlling the first drive means and the second drive means;
A control means for controlling the drive controller, and a shape measuring method using a coordinate measuring machine comprising:
The control means includes
Storing a part program in which the posture information of the probe head is described in the work coordinate system in which the origin and the reference XYZ axes are set;
The arrangement state of the object to be measured placed on the table is detected, a new reference Z axis is determined for the object to be measured, and then a new reference XY axis is determined to set a new reference XYZ axis And a step to set a new origin,
Obtaining a probe head posture correction value in the vertical and horizontal directions from the new origin and the new reference XYZ axis and the origin and the reference XYZ reference axis;
Reading the part program, correcting the attitude of the probe head based on the attitude correction value, converting the attitude information of the probe head from a work coordinate system to a machine coordinate system, and instructing the drive controller;
A shape measuring method using a three-dimensional measuring machine.   The steps of setting a new reference XYZ axis and setting a new origin include determining at least three points on the plane of the object to be measured by the probe head and determining the new reference Z axis; The shape measuring method using the coordinate measuring machine according to claim 3, further comprising: measuring at least two points on the side surface to determine the new reference XY axis.

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