JP5359651B2 - Shape measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shape measuring device that facilitates measuring a shape of a workpiece. <P>SOLUTION: A CAD/CAM device 51 of an NC machining device 1 forms measurement NC data by using a posture of a machining tool 25 for the workpiece W in machining information as it is, when a posture vector of the machining tool 25 at a measurement point in the machining information coincides with a normal vector at the point in CAD/CAM data. If there is a measurement point where the posture vector of the machining tool 25 does not coincide with the normal vector of the workpiece W, measurement postures of a probe are ranked in accuracy based on accuracy of measurement, and the measurement posture of the probe for the workpiece W is set at each measurement point priority from the point with the highest accuracy, so as to form the measurement NC data. For a plurality of measurement postures with the equal priority, the data with a less amount of movement of driving shafts 27 and 28 of a machining center 2 required until each measurement posture is reached is set as the measurement posture data of the probe. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a shape measuring apparatus that measures the shape of a workpiece by using an NC machine tool having at least a rectilinear axis and a rotary shaft as a drive shaft capable of relatively moving the workpiece and a tool.

  Conventionally related to machine tools that machine a workpiece with a machining center, which is an NC machine tool, measure the shape of the machined workpiece with a probe (contact type probe) attached to the spindle of the machining center, and rework the workpiece based on the measurement result There was a technique (see, for example, Patent Document 1).

  Usually, a workpiece machined by an NC machine tool including a rotating shaft tends to have a complicated outer peripheral surface shape, and a three-dimensional shape measuring device has been used for shape measurement. Therefore, when the workpiece set on the machine tool is once removed and the shape is measured and then reworked, it is necessary to set it again on the machine tool.

As described above, repeating the detachment of the workpiece with respect to the machine tool has poor workability, and has significantly deteriorated the production efficiency of the workpiece.
On the other hand, the NC machine tool disclosed in the prior art described above is a wasteful work such as detaching and transporting a workpiece that can be reworked by measuring the shape while the workpiece is attached to the machine tool. Therefore, it was possible to improve the productivity.

Japanese Patent Laid-Open No. 5-146949

However, as described above, the workpiece machined by the NC machine tool including the rotary shaft has a complicated shape, and it is quite difficult to control the movement of the probe attached to the main spindle of the NC machine tool. Met.
First, it goes without saying that the probe must avoid interference with the workpiece, but in addition to that, the probe is different from the tool, and the measurement accuracy depends on the posture when contacting the workpiece. have. For these reasons, it is difficult to create NC data for measurement that controls the movement of the probe, which has hindered the spread of workpiece shape measurement by NC machine tools. In the above-described prior art, the method for forming the measurement NC data for controlling the probe moving operation is not specifically described.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a shape measuring apparatus that can easily measure the shape of a workpiece.

In order to solve the above-described problem, the configuration feature of the invention of the shape measuring apparatus according to claim 1 has at least a linear axis and a rotary axis as drive axes capable of relatively moving the workpiece and the tool. In a shape measuring apparatus for measuring the outer peripheral surface shape of the workpiece using an NC machine tool, the shape measuring device extends in a certain axial direction and is moved relative to the workpiece by the drive shaft, and the outer circumference of the workpiece A measurement probe for bringing the tip into contact with the surface, CAD / CAM data storage means for storing CAD / CAM data for specifying the shape of the workpiece, and at the time of workpiece measurement based on the CAD / CAM data Measurement NC data forming means for forming measurement NC data which is data relating to the position and orientation of the measurement probe with respect to the workpiece, and the formed measurement Based on the NC data, and a drive control means for operating the drive shaft, the measuring NC data forming means, said when the tip of the probe abuts the workpiece with respect to the axial direction of the Burobu The order of the shape measurement accuracy is provided to a plurality of postures of the probe whose shape measurement accuracy varies depending on the direction in which the tip of the probe contacts the work, and the order is determined at each point on the outer peripheral surface of the work. The NC data for measurement is formed so as to set the posture of the probe with respect to the workpiece preferentially from the highest .

The structural feature of the invention according to claim 2 is the shape measuring apparatus according to claim 1,
The measurement NC data forming means includes:
Forming the NC data for measurement using machining information relating to the position and orientation of the tool with respect to the workpiece at the time of machining, which is formed based on the CAD / CAM data.

The structural feature of the invention according to claim 3 is the shape measuring apparatus according to claim 2,
The measurement NC data forming means includes:
When the direction of the posture vector of the tool at the point on the workpiece in the machining information matches the direction of the normal vector at the point on the outer peripheral surface of the workpiece in the CAD / CAM data, the machining information The measurement NC data is formed with the posture of the tool in the workpiece as the posture of the probe with respect to the workpiece.

According to a fourth aspect of the present invention, in the shape measuring apparatus according to any one of the first to third aspects, the drive shaft includes an X axis extending in a horizontal direction, a Y axis extending in a vertical direction, and The probe has three linear axes of the Z axis orthogonal to the X axis and the Y axis, and the probe extends in the Z axis direction and is a probe capable of measuring in all directions by a contact portion formed at the tip. The measurement NC data forming means has a first posture in which the probe is brought into contact with the workpiece by moving the probe relative to the workpiece in a direction parallel to the Z-axis as a first order. A second position in which the probe is moved relative to the workpiece in a direction parallel to one of the X axis and the Y axis as a second order, and the probe is set as a third order. X for workpiece The third posture to abut by relatively moving an angle of 45 °, and in a direction orthogonal to the remaining one axis relative to two axes of the Y-axis and the Z-axis, that at least It is.

The structural feature of the invention according to claim 5 is the shape measuring apparatus according to claim 4,
The position of the probe with respect to the work at each point on the outer peripheral surface of the work is provided with interference determination means for determining the presence or absence of interference of the probe with the work,
The measurement NC data forming means includes:
For a plurality of postures of the probe with respect to the workpiece having the same rank, when there is no interference of the probe with the workpiece, the movement amount of the drive shaft required to reach the posture is small, Setting the posture of the probe relative to the workpiece.

According to the shape measuring apparatus of the first aspect, the measuring NC data forming means forms the measuring NC data based on the CAD / CAM data, so that the probe relative to the workpiece is determined based on the workpiece shape. Since the moving operation can be controlled, highly accurate shape measurement can be performed.
At each point on the outer peripheral surface of the workpiece in the CAD / CAM data, the measurement accuracy by the probe can be further improved by preferentially setting the posture of the probe with respect to the workpiece in the order of high accuracy.

  According to the shape measuring apparatus of the second aspect, the measuring NC data forming means has a track record for avoiding interference with the workpiece, and uses the machining information on the position and orientation of the tool with respect to the workpiece at the time of machining. By forming the NC data, it is possible to greatly reduce the calculation process for forming the measurement NC data.

  According to the shape measuring apparatus according to claim 3, the direction of the tool attitude vector at the point on the workpiece in the machining information is the direction of the normal vector at the point on the outer peripheral surface of the workpiece in the CAD / CAM data. When they match, by forming the NC data for measurement as the posture of the tool in the machining information with respect to the workpiece of the probe, the axial direction of the probe and the normal direction to the outer peripheral surface of the workpiece are matched. The NC data for measurement in which the probe comes into contact with the workpiece can be easily formed, and the measurement accuracy can be improved.

According to the shape measuring apparatus of the fourth aspect, the measurement posture of the probe is set to the first posture, the second posture, and the third posture in descending order of accuracy, thereby easily improving the measurement accuracy by the probe. Can be made.

  According to the shape measuring apparatus according to the fifth aspect of the present invention, when there is no interference with the workpiece of the probe with respect to a plurality of postures of the probe having the same accuracy order, the NC machine tool required until the posture is reached. By setting the movement amount of the drive shaft with a small amount as the posture data of the probe, it is possible to reduce the decrease in measurement accuracy due to the movement of the probe and further improve the measurement accuracy.

The perspective view which showed the structure of NC processing apparatus by Embodiment 1 of this invention The block diagram which mainly showed the electrical structure of NC processing apparatus shown in FIG. Process diagram showing machining, shape measurement, and correction machining method of NC machining apparatus according to Embodiment 1 Simplified diagram for explaining the relationship between workpiece shape and probe measurement posture Simplified view of the tip of the probe viewed in a direction parallel to the Y axis to show each measurement orientation Simplified view of the tip of the probe viewed in the direction parallel to the Z axis to show each measurement orientation The figure showing the table which showed the relation between the measurement posture of the probe and the measurement accuracy The flowchart showing the formation method of NC data for measurement of NC processing device by Embodiment 2 Simplified diagram showing machining tool posture vector and normal vector on the outer peripheral surface of the workpiece The perspective view which showed the structure of NC processing apparatus by Embodiment 3. The block diagram which mainly showed the electrical structure of NC processing apparatus shown in FIG. Partial enlarged view showing the work trace device shown in FIG.

<Embodiment 1>
An NC processing apparatus 1 (corresponding to the shape measuring apparatus of the present invention) according to Embodiment 1 of the present invention will be described with reference to FIGS. The NC machining apparatus 1 according to the present embodiment uses a drive shaft that can move a workpiece and a tool relatively, a linear axis is an X axis, a Y axis, and a Z axis, and a rotation axis is an A axis (around the X axis). A machining center 2 (corresponding to the NC machine tool of the present invention) and a control box 5 capable of simultaneous machining of five axes, which are two axes of a rotation axis) and a B axis (rotation axis around the Y axis) (see FIG. 2).

  A column 22 is mounted on the base 21 of the machining center 2 so as to be movable in the horizontal Z-axis direction. Further, a spindle head 23 is attached to one side surface of the column 22 so as to be movable in the Y-axis direction (perpendicular to the Z-axis) which is a vertical direction. It is attached so as to protrude in the Z-axis direction. Various processing tools 25 (corresponding to the tool of the present invention) can be replaced with the main shaft 24. In addition, a touch sensor 4 described later can be attached to and detached from the spindle 24 in place of the processing tool 25 (shown in FIGS. 1 and 2).

  On the other hand, a work table 26 is placed on the base 21 so as to face the column 22. The work table 26 includes a tilt table 26a and a rotary table 26b, and a work W (corresponding to the work of the present invention) can be attached thereto. The tilt table 26a is movable in the X-axis direction, which is a horizontal axis orthogonal to both the Y-axis and the Z-axis, and is rotatable about the X-axis (A-axis). The rotary table 26b is provided on the tilt table 26a and is rotatable about the Y axis (B axis) (shown in FIG. 1).

  The column 22 and the spindle head 23 are each connected to a drive shaft 27 including a drive servo motor. The work table 26 is also connected to a drive shaft 28 that also includes a servo motor for driving. The servo motors of the drive shafts 27 and 28 (corresponding to the drive shaft of the present invention) are both controlled by the NC drive control unit 29 (corresponding to the drive control means of the present invention) in their drive amount and drive speed.

  A data file 30 is connected to the NC drive control unit 29, and the NC drive control unit 29 controls the operation of each drive shaft 27, 28 based on various data in the data file 30. The machining NC data file 31 included in the data file 30 stores machining NC data (reference NC data) that is data related to the position and orientation of the machining tool 25 with respect to the workpiece W when machining the workpiece W.

  The measurement NC data file 32 stores measurement NC data that is data related to the position and orientation of the probe 42 with respect to the workpiece W when the shape of the workpiece W after processing by the touch sensor 4 is measured. The correction machining NC data file 33 stores correction machining NC data, which is data relating to the position and orientation of the machining tool 25 with respect to the workpiece W when the shape of the workpiece W is corrected.

  The control box 5 includes a CAD / CAM device 51 (corresponding to CAD / CAM data storage means and measurement NC data forming means of the present invention) and a main control unit 52. The CAD / CAM device 51 forms and stores CAD / CAM data for specifying the product shape of the workpiece W according to the operation of the designer.

  Further, the CAD / CAM device 51 creates machining NC data based on the CAD / CAM data, and transmits the created machining NC data to the machining NC data file 31. Further, the CAD / CAM device 51 is formed based on CAD / CAM data, and holds machining information including data on the position and orientation of the machining tool 25 with respect to the workpiece W when machining the workpiece W. The CAD / CAM device 51 creates measurement NC data using the processing information, and transmits the created measurement NC data to the measurement NC data file 32. Further, the CAD / CAM device 51 creates NC data for correction machining based on the shape measurement result of the workpiece W by the touch sensor 4 performed according to the NC data for measurement, and transmits it to the NC data file 33 for correction machining. .

The main control unit 52 activates the machining center 2 and the CAD / CAM device 51 by operating a start switch provided in the control box 5.
The touch sensor 4 is attached to the main shaft 24 so as to face the workpiece W fixed to the work table 26 in the Z-axis direction (shown in FIG. 1). A probe 42 (corresponding to the measurement probe of the present invention) extends in the horizontal direction (Z-axis direction) from the conical body portion 41 of the touch sensor 4, and a spherical contact portion 43 is formed at the tip thereof. Is formed.

  The touch sensor 4 is moved together with the main shaft 24 in the Y-axis direction and the Z-axis direction. The probe 42 always maintains a horizontal posture, but is tilted when the contact portion 43 touches the outer peripheral surface of the workpiece W, and the amount of displacement is detected. The displacement amount of the contact part 43 is transmitted to the CAD / CAM device 51, and the coordinates of the contact position of the contact part 43 on the workpiece W are calculated.

  Next, based on FIG. 3, a method from the creation of measurement NC data using the NC machining apparatus 1 in the present embodiment to the correction machining through shape measurement will be described. First, when the main control unit 52 activates the machining center 2 and the CAD / CAM device 51, the CAD / CAM device 51 determines measurement points on the outer peripheral surface of the workpiece W in order to create NC data for measurement (step S301). ).

  Then, the CAD / CAM device 51 creates measurement NC data based on the processing information described above and stores it in the measurement NC data file 32 (step S302). The measurement NC data includes data related to the posture of the probe 42 relative to the workpiece W and data related to the position of the probe 42 relative to the workpiece W when each measurement point is measured.

  The measurement is performed in a state where each rotation axis is indexed to a predetermined angle (a state where the angle is fixed). That is, one piece of data regarding the posture is set for each measurement point. In the present embodiment, the data related to the posture at each measurement point is created using the position and posture of the machining tool 25 at the measurement point in the machining information with respect to the workpiece W as they are. That is, the posture of the machining tool 25 with respect to the workpiece W at the point in the machining information corresponding to each determined measurement point is the posture of the probe 42 with respect to the workpiece W in the measurement NC data.

  The data regarding the position of the probe 42 with respect to the workpiece W when measuring each measurement point includes data for moving from the current position to the vicinity of the measurement point, data for approaching the measurement point from the vicinity, and the vicinity from the measurement point. It includes data to be evacuated to a position and data to be moved from the neighboring position to the next position.

Here, the contact direction of the contact portion 43 to the workpiece W at each measurement point is set so as to coincide with the axial direction of the probe 42 in order to avoid interference with the workpiece W and the workpiece table 26. That is, the data for approaching from the vicinity position to the measurement point and the data for retreating from the measurement point to the vicinity position are data for moving the contact portion 43 in the axial direction of the probe 42.
Note that when the contact direction of the contact portion 43 at the measurement point is made to coincide with the normal direction of the measurement point of the workpiece W, the measurement can be performed with the highest accuracy. The tangential direction may coincide with the normal direction of the measurement point of the workpiece W.

  When the creation of the measurement NC data is completed, the machining center 2 starts machining the workpiece W fixed to the workpiece table 26 (step S303). For machining of the workpiece W, the NC drive control unit 29 of the machining center 2 operates the spindle 24 and the drive shafts 27 and 28 based on the machining NC data created by the CAD / CAM device 51, so that the workpiece W of the machining tool 25 is processed. This is done by controlling the position and posture with respect to.

  When the machining of the workpiece W by the machining center 2 is completed, the machining tool 25 attached to the main shaft 24 is replaced with the touch sensor 4. Thereafter, the NC drive control unit 29 operates the drive shafts 27 and 28 based on the measurement NC data stored in the measurement NC data file 32 to move the workpiece W and the main shaft 24, and to probe the workpiece W. The relative position and orientation of 42 are set (step S304). The probe 42 contacts the outer peripheral surface of the workpiece W and measures the outer peripheral surface shape of the workpiece W in a predetermined posture (step S305).

  As described above, the data related to the posture of the measurement NC data is created by using the position and posture of the machining tool 25 in the machining information as it is with respect to the workpiece W. Therefore, when measuring the shape of the workpiece W, The posture of the probe 42 with respect to the outer peripheral surface has the same relationship as the posture of the processing tool 25 with respect to the outer peripheral surface of the workpiece W when the workpiece W is processed.

  When the shape measurement of the workpiece W is completed, the CAD / CAM device 51 starts calculating the shape error of the workpiece W (step S306). The CAD / CAM device 51 compares the result of the shape measurement of the workpiece W by the touch sensor 4 with the CAD / CAM data, and calculates the shape error of the workpiece W. The CAD / CAM device 51 extracts a portion of the workpiece W where the calculated shape error is equal to or greater than a predetermined value (step S307).

  Thereafter, the CAD / CAM device 51 determines the angle with respect to the A and B axes of the drive shaft 28 for performing the correction processing for the part of the workpiece W where the shape error has occurred. In this embodiment, correction processing is performed with the A and B axes fixed. That is, the index angles of the A and B axes when performing the correction process are determined. When the CAD / CAM device 51 determines the angles related to the A and B axes of the drive shaft 28, the CAD / CAM device 51 creates NC data for correction processing based on the shape error of the workpiece W and the angles related to the A and B axes. The file 33 is stored (step S308).

Finally, the NC drive control unit 29 of the machining center 2 operates the drive shaft 28 based on the formed correction machining NC data to determine the posture of the machining tool 25 relative to the workpiece W (step S309). Thereafter, the NC drive control unit 29 operates the main shaft 24 and the drive shafts 27 and 28 to control the position of the machining tool 25 with respect to the workpiece W, and performs the correction machining of the portion of the workpiece W where the shape error has occurred ( Step S310).
The above-described steps from the processing of the workpiece W to the correction processing are executed from the beginning to the end while the workpiece W is fixed to the workpiece table 26 of the machining center 2.

  According to the present embodiment, the CAD / CAM device 51 forms machining information based on CAD / CAM data, and further forms measurement NC data based on the machining information, so that the shape of the workpiece W is used as a reference. Since the relative movement operation of the probe 42 with respect to the workpiece W can be controlled, highly accurate shape measurement can be performed.

  Further, the CAD / CAM device 51 forms NC data for measurement using the position and orientation of the machining tool 25 in the machining information as it is, which has a proven record in avoiding interference with the workpiece W and the work table 26. By doing so, the calculation process for forming the measurement NC data can be greatly reduced.

<Embodiment 2>
Based on FIGS. 4 to 9, a method for forming measurement NC data in the CAD / CAM device 51 according to the second embodiment of the present invention will be described focusing on differences from the first embodiment. Also in this embodiment, the shape measurement of the workpiece W is performed by the NC machining apparatus 1 shown in FIGS. 1 and 2, and the steps from the machining of the workpiece W to the correction machining are performed according to FIG. To do.

  First, the contact posture of the probe 42 to the workpiece W when measuring the shape of the workpiece W after processing will be described. In the following description, the contact portion 43 side in the axial direction of the probe 42 is referred to as the front, and the main body portion 41 side is referred to as the rear. As shown in FIG. 7, when the contact portion 43 of the probe 42 is brought into contact with the outer peripheral surface of the workpiece W, the measurement posture of the probe 42 with respect to the normal direction on the measurement point of the workpiece W is changed from the first posture to the fifth posture. I divided it into postures.

  The first posture to the fifth posture shown in FIG. 7 are the states in which the posture directions of the probes 42 indicated by the arrows in FIG. 5 and FIG. 6 coincide with the normal direction of the outer peripheral surface of the workpiece W. This means that the probe 42 is brought close to the workpiece W in the normal direction. That is, for example, when the second posture is selected, the normal direction of the outer peripheral surface of the workpiece W is matched with one of the arrow directions indicated by (2) in FIG. 5 and FIG. The workpiece W is brought into contact with the workpiece W in the direction of the arrow.

  In FIG. 7, the “measurement direction” column represents the axial component included in the contact direction of the contact portion 43 with respect to the workpiece W for each measurement posture, and the “measurement accuracy rank” column represents each measurement posture. The measurement accuracy is ranked (accuracy ranking), and the number described in the column “illustrated” is the same as the contact direction of the contact portion 43 with respect to the workpiece W shown in FIGS. I'm doing it.

  In FIG. 7, the first posture is when the probe 42 is moved forward (relatively moved) with respect to the workpiece W in a direction parallel to the Z axis and the contact portion 43 is brought into contact with the workpiece W. The second posture is when the probe 42 is advanced (relatively moved) in any one of the direction parallel to the X axis and the direction parallel to the Y axis, and the contact portion 43 is brought into contact with the workpiece W. In the third position, the probe 42 is moved (relatively moved) in a direction that makes an angle of 45 ° with respect to two of the X, Y, and Z axes and is orthogonal to the remaining one axis. In this case, the contact portion 43 is brought into contact with the workpiece W.

  In the fourth posture, the probe 42 makes an angle of 45 ° with respect to the three axes of the X axis, the Y axis, and the Z axis, and advances (relatively moves) forward to bring the contact portion 43 into contact with the workpiece W. This is the case. In the fifth posture, the probe 42 forms an angle of 45 ° with respect to the three axes of the X axis, the Y axis, and the Z axis, and advances (relatively moves) backward to bring the contact portion 43 into contact with the workpiece W. This is the case. As can be seen from FIG. 7, the measurement accuracy is highest when shape measurement is performed in a state where the posture of the probe 42 with respect to the workpiece W is the first posture.

  As shown in FIG. 4, consider a state in which an irregularly shaped workpiece WK is placed on the workpiece table 26 of the NC machining apparatus 1 for shape measurement. In this case, as described above, it is desirable to bring the probe 42 into contact with the work WK with a high measurement accuracy at all measurement points on the outer peripheral surface of the work WK.

However, when the probe 42 is brought close to the workpiece WK, naturally, if interference occurs between the probe 42 and the workpiece WK or the workpiece table 26, measurement cannot be performed. Therefore, at each measurement point on the outer peripheral surface of the workpiece WK, the presence or absence of interference between the probe 42 and the workpiece WK or the workpiece table 26 is considered in order from the first posture.
That is, when shape measurement is performed at the measurement point indicated by ◯ on the outer peripheral surface of the workpiece WK shown in FIG. 4, no interference occurs between the two, so that the probe 42 is in the first posture. The contact portion 43 of 42 is brought into contact with the workpiece WK.

  Further, when shape measurement is performed at the measurement point represented by Δ on the outer peripheral surface of the work WK, interference occurs between the work WK or the work table 26 in a state where the probe 42 is in the first posture. In the state where the probe 42 is in the second posture, no interference occurs between them, so the contact portion 43 of the probe 42 is brought into contact with the workpiece WK while the probe 42 is in the second posture.

  Further, when the shape measurement is performed at the measurement point represented by x on the outer peripheral surface of the workpiece WK, there is interference between the workpiece WK or the work table 26 in a state where the probe 42 is in the first posture or the second posture. However, since interference does not occur between the probe 42 and the probe 42 in the third posture, the contact portion 43 of the probe 42 is brought into contact with the workpiece WK while the probe 42 is in the third posture.

  Hereinafter, based on FIG. 8 and FIG. 9, the formation method of the NC data for measurement in this embodiment is demonstrated concretely. First, a measurement point on the outer peripheral surface of the workpiece W is determined (step S801). Next, N in the memory of the CAD / CAM device 51 is set to 1 (step S802), and the machining tool in the machining information formed in the CAD / CAM device 51 on the first measurement point (measurement point 1). 25 posture vectors (tool axis vectors) are compared with normal vectors on the outer peripheral surface of the workpiece W in the CAD / CAM data (step S803).

  Here, as shown in FIG. 9, the orientation vector T of the machining tool 25 in the machining information on each first measurement point, and the normal vector R on the outer peripheral surface of the workpiece W in the CAD / CAM data, It is determined whether or not the directions match.

  Next, after N in the memory is incremented by one (step S804), it is determined whether N has exceeded M (step S805). M is the number of measurement points set on the outer peripheral surface of the workpiece W. When N does not exceed M, as described above, the comparison between the posture vector T of the machining tool 25 at each measurement point and the normal vector R on the outer peripheral surface of the workpiece W is continued.

  When the comparison between the posture vector T and the normal vector R at each measurement point is completed, the direction between the posture vector T of the machining tool 25 and the normal vector R on the outer peripheral surface of the workpiece W is the same on all the measurement points. It is determined whether or not it has been done (step S806). When it is determined that the orientation of the orientation vector T and the normal vector R is the same on all measurement points, measurement is performed using the data on the orientation of the machining tool 25 with respect to the workpiece W in the machining information as it is. Data relating to the attitude of the NC data is formed (step S807). As a result, the measurement NC data is formed with the data related to the posture of the machining tool 25 in the machining information with respect to the workpiece W as the posture of the probe 42 relative to the workpiece W.

  This is because the machining information has a track record of machining the workpiece W based on this, and even if applied to the measurement NC data as it is, interference between the probe 42 and the workpiece W or the workpiece table 26 does not occur, and This is because the shape of the workpiece W can be measured in a state where the probe 42 always maintains the above-described first posture, so that highly accurate shape measurement can be performed. In this case, it goes without saying that measurement is performed with the probe 42 in contact with the workpiece W in the axial direction in a state where the probe 42 is kept in the first posture with respect to the workpiece W.

  On the other hand, if it is determined that the orientation of the orientation vector T and the normal vector R does not coincide with each other on any measurement point, N in the memory of the CAD / CAM device 51 is set to 1 again (step) In step S808, a normal line on the outer peripheral surface of the workpiece W is calculated on the first measurement point (step S809).

  Next, P in the memory of the CAD / CAM device 51 is set to 1 (step S810), and the drive shaft 28 when the probe 42 is set to the first posture having the highest measurement accuracy rank on the first measurement point. Is calculated (step S811). Thereafter, whether or not interference occurs between the workpiece W and the work table 26 when the probe 42 is set in the first posture on the first measurement point and approached to the workpiece W in the axial direction thereof. Is determined (step S813: corresponds to the interference determination means of the present invention).

When it is determined that interference occurs between the probe 42 in the first posture and the work W or the work table 26, P in the memory is set to 2 (step S812), and the probe 42 is set to the measurement accuracy ranking. After calculating the rotation angle of each drive shaft 28 when the second position is the second highest (step S811), when the probe 42 is in the second position on the first measurement point, the workpiece W or It is determined whether or not interference occurs with the work table 26 (step S813). Thereafter, the measurement posture is sequentially changed toward the fifth posture until a posture in which it is determined that no interference occurs between the probe 42 and the workpiece W or the work table 26 is found.
Thus, on the first measurement point, the measurement posture of the probe 42 is preferentially set from the first posture having a high accuracy rank, and no interference occurs between the probe 42 and the workpiece W or the workpiece table 26. The measurement posture to be determined is determined.

  When it is determined that no interference occurs between the probe 42 and the work W or the work table 26, it is determined whether or not there are a plurality of postures of the probe 42 with respect to the work W at which no interference occurs (step S814). For example, when the probe 42 can be advanced in a plurality of directions with respect to the workpiece W as in the second posture, the drive shaft 28 until the probe 42 reaches each measurement posture in each case. A rotational movement amount is calculated (step S815).

  The calculated rotational movement amounts of the drive shafts 28 are compared with each other (step S816), and the measurement posture of the probe 42 that minimizes the movement amount is selected, and the movement amount of each drive shaft 28 in that case is determined. (Step S817). When it is determined that there is only one posture of the probe 42 with respect to the workpiece W that does not cause interference (step S814), the measurement posture in that case is selected.

When the measurement posture of the probe 42 on the first measurement point is determined, N in the memory is incremented by one (step S818), and the measurement of the probe 42 on the second and subsequent measurement points is performed in the same manner as described above. Posture is determined. When the measurement postures of the probes 42 at all measurement points are determined, the flow for forming the measurement NC data ends (step S819).
In the method of forming NC data for measurement in the present embodiment, Japanese Patent No. 3917114 discloses a method for reducing movement errors caused by assembly errors and machining errors of the drive shaft 28 or the work table 26. The conventional technology is effective.

According to the present embodiment, the direction of the orientation vector T of the machining tool 25 at the measurement point on the workpiece W in the machining information is the normal vector R at the point on the outer peripheral surface of the workpiece W in the CAD / CAM data. When the direction coincides with the direction, NC data for measurement is formed with the data regarding the posture of the machining tool 25 in the machining information with respect to the workpiece W as the posture of the probe 42 with respect to the workpiece W.
This makes it possible to easily form measurement NC data for bringing the probe 42 into contact with the workpiece W so that the axial direction of the probe 42 and the normal direction to the outer peripheral surface of the workpiece W coincide with each other. Can be improved.

In addition, by setting the posture of the probe 42 with respect to the workpiece W preferentially from the one with the highest accuracy rank at each measurement point on the outer peripheral surface of the workpiece W in the CAD / CAM data, the measurement accuracy by the probe 42 is further improved. It can be further improved.
In addition, with respect to a plurality of postures of the probe 42 with respect to the workpiece W having the same accuracy ranking, if there is no interference with the workpiece W or the work table 26 of the probe 42, the rotational movement of the drive shaft 28 required to reach the measurement posture. By setting a small amount as the posture data of the probe 42, it is possible to reduce a decrease in measurement accuracy due to the movement of the probe 42 and further improve the measurement accuracy.

<Embodiment 3>
Based on FIG. 10 thru | or FIG. 12, NC processing apparatus 1A by Embodiment 3 of this invention is demonstrated. An NC machining apparatus 1A according to the present embodiment includes a machining center 2, a control box 5, and a work trace apparatus 6 similar to those of the first embodiment as shown in FIGS.

  The work trace device 6 is provided so as to face the main shaft 24 with the work table 26 interposed therebetween (shown in FIG. 10). As shown in FIG. 12, a support body 62 is provided at the base 61 of the work trace device 6 so as to be movable in the vertical direction (Y-axis direction). A straight rod 63 protrudes from the support 62 so as to be able to advance and retreat in the Z-axis direction, and a touch sensor 64 is attached to the tip thereof. A probe 66 (corresponding to the measurement probe of the present invention) extends in the horizontal direction (Z-axis direction) from the conical body portion 65 of the touch sensor 64, and a spherical contact portion 67 is formed at the tip thereof. Is formed.

  The work trace device 6 is activated by the main control unit 52, and the support 62 and the rectilinear rod 63 are respectively moved by a drive motor (not shown) controlled by the NC drive control unit 29. The probe 66 always maintains a horizontal posture, but tilts when the contact portion 67 touches the outer peripheral surface of the workpiece W, and the amount of displacement is detected. The displacement amount of the contact part 67 is transmitted to the CAD / CAM device 51, and the coordinates of the contact position of the contact part 67 on the workpiece W are calculated. Since other configurations are the same as those in the first embodiment, description thereof is omitted.

<Other embodiments>
The present invention is not limited to the above-described embodiments, and can be modified or expanded as follows.
A machine tool in which the shape measuring apparatus according to the present invention can be used is an NC machine tool having at least one linear axis and one rotary axis as drive axes capable of relatively moving a workpiece and a tool. I just need it.

In the embodiment described above, the measurement NC data file formed in the machining center may be provided in the CAD / CAM device.
In the process by the NC machining apparatus shown in FIG. 3, after the workpiece is machined by the machining center (step S303), measurement NC data may be created by the CAD / CAM apparatus (step S302).

  In the drawings, 1, 1A is an NC machining device (shape measuring device), 2 is a machining center (NC machine tool), 25 is a machining tool (tool), 27 and 28 are drive shafts, and 29 is an NC drive control unit (drive control means). , 42 and 66 are probes (measurement probes), 51 is a CAD / CAM device (CAD / CAM data storage means, measurement NC data forming means), and W is a workpiece.

Claims (5)

In a shape measuring device for measuring the outer peripheral surface shape of the workpiece, using an NC machine tool having at least a linear axis and a rotating shaft as a drive shaft capable of relatively moving the workpiece and the tool,
A measurement probe that extends in a certain axial direction, is moved relative to the workpiece by the drive shaft, and abuts the tip against the outer peripheral surface of the workpiece;
CAD / CAM data storage means for storing CAD / CAM data for specifying the shape of the workpiece;
NC data forming means for measurement for forming NC data for measurement, which is data relating to the position and orientation of the measurement probe with respect to the workpiece, based on the CAD / CAM data,
Drive control means for operating the drive shaft based on the formed measurement NC data, and
The measurement NC data forming means includes:
When the tip of the probe comes into contact with the workpiece, the probe has a plurality of postures in which the shape measurement accuracy varies depending on the direction in which the tip of the probe contacts the workpiece with respect to the axial direction of the probe. Providing the order according to the shape measurement accuracy, and forming the measurement NC data so as to preferentially set the posture of the probe with respect to the work from the highest order at each point on the outer peripheral surface of the work. A feature measuring device. The measurement NC data forming means includes:
The NC data for measurement is formed using machining information about the position and orientation of the tool with respect to the workpiece at the time of machining, which is formed based on the CAD / CAM data. Shape measuring device. The measurement NC data forming means includes:
When the direction of the posture vector of the tool at the point on the workpiece in the machining information matches the direction of the normal vector at the point on the outer peripheral surface of the workpiece in the CAD / CAM data, the machining information 3. The shape measuring apparatus according to claim 2, wherein the measuring NC data is formed by setting a posture of the tool with respect to the workpiece as a posture of the probe with respect to the workpiece. The drive shaft has three linear axes: an X axis extending in the horizontal direction, a Y axis extending in the vertical direction, and a Z axis orthogonal to the X axis and the Y axis,
The probe is a probe that extends in the Z-axis direction and can measure in all directions by a contact portion formed at a tip,
The measurement NC data forming means includes:
The first posture in which the probe is moved relative to the workpiece in a direction parallel to the Z-axis as a first rank, and the probe is moved to the workpiece as the second rank. A second posture in which the probe moves relative to one of the X axis and the Y axis in a direction parallel to the X axis and the Y axis, and a third order, and the probe is placed on the workpiece with respect to the X axis and the Y axis. And at least a third posture that makes an angle of 45 ° with respect to two of the Z-axis and makes a relative movement in a direction orthogonal to the remaining one axis to make contact. The shape measuring apparatus according to any one of claims 1 to 3. The position of the probe with respect to the work at each point on the outer peripheral surface of the work is provided with interference determination means for determining the presence or absence of interference of the probe with the work,
The measurement NC data forming means includes:
For a plurality of postures of the probe with respect to the workpiece having the same rank, when there is no interference of the probe with the workpiece, the movement amount of the drive shaft required to reach the posture is small, The shape measuring apparatus according to claim 4, wherein the shape measuring apparatus is set as a posture of the probe with respect to a workpiece.

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