JP6603203B2 - Method and system for measuring position of object in machine tool - Google Patents

Description

  The present invention relates to a position measurement method and a position measurement system for measuring the position of an object such as a tool or a workpiece in a machine tool.

In a machine tool that processes a workpiece mounted on a table with a rotating tool mounted on the spindle, the tool length and workpiece position are automatically measured and corrected for high-precision machining. The method is used.
As an automatic measuring method of the tool length, for example, a laser sensor 10 as shown in FIG. 2 or a touch sensor 20 as shown in FIG. 3 is used.
First, the laser sensor 10 includes a light emitting unit 11, a light receiving unit 12, and a base unit 13 that supports the light emitting unit 11 and the light receiving unit 12. The laser sensor 14 outputs laser light 14 from the light emitting unit 11, and Receive light. A signal is emitted when the laser beam 14 is blocked by an object and the light receiving rate is below a certain level. Here, the tool 9 is mounted on the main shaft 2 and the tool 9 is rotated at a predetermined speed, while the tool 9 is brought close to the laser beam 14 by the Z axis. send. The machine tool control device that has detected the signal stores the position of the Z-axis at the time of receiving the signal or taking into account the delay. The same is performed for the reference tool that is the reference for the length of each tool, and the difference between the Z-axis position of the tool 9 and the Z-axis position of the reference tool is set as the length of the tool 9.
Next, the touch sensor 20 is a device that emits a signal when contact is detected. The tool 9 is attached to the spindle 2, the tool 9 is moved closer to the touch sensor 20 by the Z axis, and a signal is output when the tool 9 comes into contact. send. The control device that has detected the signal stores the position of the Z-axis at the time of receiving the signal or considering the delay. The same is performed for the reference tool that is the reference for the length of each tool, and the difference between the Z-axis position of the tool 9 and the Z-axis position of the reference tool is set as the length of the tool 9.

On the other hand, for example, a touch probe 30 as shown in FIG. 4 is used as an automatic measurement method of the position of the workpiece. The touch probe 30 is a device that outputs a signal when the contactor comes into contact with an object. The touch probe 30 is attached to the spindle 2 and is moved closer to the workpiece 31 on the table 3 by the Z axis. A signal is output when the object 31 is touched. The control device that has detected the signal acquires the position of the Z axis at the time of receiving the signal or taking into account the delay.
Further, the position of the workpiece 31 (in this case, the height) can be obtained by measuring the length of the touch probe 30 with respect to the reference tool in advance and correcting the measurement as a correction value in the longitudinal direction of the touch probe 30. it can. However, since the touch probe 30 changes in a certain length until it comes into contact with the object and outputs the trigger signal, the touch probe 30 needs to have an actual length when the touch probe 30 comes into contact and outputs the trigger signal. Become.
However, since the touch probe 30 is not in contact with the laser sensor 10, the length when the touch probe 30 is in contact cannot be measured.
On the other hand, in the touch sensor 20, since the operation resistances of the touch sensor 20 and the touch probe 30 are different from each other, both cannot output a trigger signal at the same time, and the touch-contact length of the touch probe 30 cannot be measured.

Therefore, a method using a reference tool (hereinafter referred to as “method 1”) is known as a method for measuring the contact probe length. In Method 1, a reference tool is mounted on the spindle, and the block gauge is moved manually while manually operating the Z axis so that the reference tool contacts the reference surface such as the table top surface via the block gauge. The position where the clearance between the block gauge and the reference tool is almost zero is found from the resistance at the time, and the position is recorded. Next, the reference plane is measured with the touch probe, that is, the Z-axis position when the touch probe comes into contact is acquired. A value obtained by subtracting the recorded Z-axis position of the reference tool and the thickness of the block gauge from the Z-axis position acquired by the touch probe is the length when the touch probe is contacted.
Patent Document 1 describes a method for measuring a contact probe length using a CCD camera. Here, first, the position of the spindle when the touch probe is brought into contact with the upper surface of the press stand to output a signal is acquired, and the tip position is measured by photographing the tip of the touch probe at the time of contact with a CCD camera. Next, the press stand is removed, and the length is returned to the length when the touch probe is not in contact, and the tip position is measured with the CCD camera. The amount of shrinkage at the time of contact is calculated from the difference between the two tip positions. The tip position of the reference tool is also measured with a CCD camera, and the position of the spindle at that time is also acquired. The contact probe contact length is obtained from the relationship between the contact shrinkage, the touch probe tip position at the time of contact, the spindle position at the time of touch probe contact, the tip position of the reference tool, and the spindle position at the reference tool. .
On the other hand, Patent Document 2 describes a method for correcting a workpiece position using a laser sensor and a reference block. First, a reference block is prepared in the vicinity of the laser sensor, and the position of the laser beam and the position (height) of the upper surface of the reference block are matched. Further, the position at the time of mounting the reference tool is stored by the laser sensor. Next, the touch probe is brought into contact with the reference block and the position is memorized. The touch probe is also brought into contact with the work piece and the position is memorized. From the difference between both positions and the position of the reference tool, Measure and correct the workpiece position. In this method, the workpiece position is measured without obtaining the contact probe contact length.

JP 2012-61570 A JP 2001-105279 A

First, in the above method 1, manual work is required, and the touch-contact length of the touch probe cannot be automatically measured. For this reason, the length of the touch probe changes due to thermal displacement or the like, and when measuring the length of the touch probe in contact, there is a problem that it is necessary to interrupt the processing and perform manual work.
Next, the technique of Patent Document 1 has a problem that an expensive measuring device using a CCD camera is required. In addition, in order to automatically remove the presser base, a mechanism and an actuator for driving the presser base are required, and there is a problem that the cost increases.
Moreover, although the technique of patent document 2 can measure the position of a workpiece without measuring the length at the time of contact of a touch probe, the laser beam position of a laser sensor and a reference block position are made to coincide, or both positions The relationship needs to be known. This is synonymous with the fact that the relationship between the length of the reference tool measured by the laser sensor and the length of the touch probe when contacting the reference block, that is, the length when the touch probe contacts, must be known. . However, there is no description about the method.

  Therefore, the present invention can acquire a long-direction correction value of a position measurement sensor such as a touch probe with a relatively inexpensive configuration, and can measure an object in a machine tool capable of measuring an object with the position measurement sensor with high accuracy. The object is to provide a position measurement method and system.

In order to achieve the above object, the invention described in claim 1 uses a machine tool having three or more translational axes, a spindle that can be rotated by mounting a tool, and a table, and uses the machine tool as the spindle. A method of measuring the position of an object fixed on the table by a position measurement sensor that can be mounted,
A tool sensor position acquisition step of mounting a reference tool serving as a reference for the length of the tool on the spindle and acquiring a detection position of the tip of the reference tool using a tool sensor;
A reference block position obtaining step for obtaining the position of the translation shaft when the reference tool mounted on the spindle is brought into direct or indirect contact with a reference block provided on the tool sensor side;
A relative position calculation step of calculating a relative position of the reference block with respect to the detection position from the detection position acquired in the tool sensor position acquisition step and the position of the translation axis acquired in the reference block position acquisition step;
A reference tool position acquisition step of mounting the reference tool on the spindle and acquiring a reference tool position that is a tip position of the reference tool using the tool sensor;
A position measurement sensor measurement step of mounting the position measurement sensor on the spindle and measuring the position of the reference block using the position measurement sensor;
The reference tool position acquired in the reference tool position acquisition step, the position of the reference block measured in the position measurement sensor measurement step, the relative position calculated in the relative position calculation step, and the length of the reference tool From the long correction value calculation step of calculating the long direction correction value of the position measurement sensor,
A position measurement step of correcting the measurement position of the object measured by the position measurement sensor mounted on the spindle using the long direction correction value of the position measurement sensor calculated in the length correction value calculation step; It is characterized by performing.
Here, the “tool sensor side” includes not only a case where a reference block is directly provided on the tool sensor but also a case where a separate reference block is provided in the vicinity of the tool sensor. The following invention is also the same.
According to a second aspect of the present invention, in the configuration of the first aspect, the tool sensor position acquisition stage to the relative position calculation stage are executed once, and the reference tool position acquisition stage to the position measurement stage are performed a plurality of times. It is characterized by performing.
According to a third aspect of the present invention, in the configuration of the first or second aspect, the position measurement sensor is in contact with an object in the position measurement sensor measurement stage and the position measured by the position measurement sensor in the position measurement stage. It is the position of the translation axis when it is detected.
According to a fourth aspect of the present invention, in the configuration according to any one of the first to third aspects, the position measurement sensor may be a contact-type sensor for the object, and the position measurement sensor may be A diameter correction value acquisition step of acquiring a radial direction correction value is further executed, and in the position measurement step, the measurement position of the object is corrected using the diameter correction value acquired in the diameter correction value acquisition step. Features.
In order to achieve the above object, the invention described in claim 5 includes three or more translation axes, a spindle that can be rotated by attaching a tool, a table, and a position measurement sensor that can be attached to the spindle. A system for measuring a position of an object fixed on the table by the position measurement sensor in a machine tool having a control device for controlling the translation shaft and the main shaft,
A reference tool serving as a reference for the length of the tool;
A tool sensor for detecting a tip position of the reference tool mounted on the spindle;
A reference block installed on the tool sensor side;
Tool sensor position acquisition means for moving the reference tool mounted on the spindle by the translation shaft and acquiring and storing the detection position of the tip of the reference tool using the tool sensor;
Reference block position acquisition for acquiring and storing the position of the translation axis at the time of contact with the reference block by moving the reference tool mounted on the spindle by the translation axis to directly or indirectly contact the reference block Means,
A relative position for calculating and storing a relative position of the reference block with respect to the detection position from the detection position acquired by the tool sensor position acquisition means and the position of the translation axis acquired by the reference block position acquisition means. A calculation means;
A reference tool position acquisition means for moving the reference tool mounted on the spindle by the translation shaft and acquiring and storing a reference tool position which is a tip position of the reference tool using the tool sensor;
Measurement position acquisition means for measuring and storing the position of the reference block with the position measurement sensor mounted on the spindle;
The reference tool position acquired by the reference tool position acquisition means, the position of the reference block acquired by the measurement position acquisition means, the relative position acquired by the relative position calculation means, and the reference tool A length correction value calculating means for calculating and storing a length direction correction value of the position measurement sensor from the length;
Position correction means for correcting the measurement position by the position measurement sensor using the length correction value stored in the length correction value calculation means and calculating the position of the object.
According to a sixth aspect of the present invention, in the configuration of the fifth aspect, the position measurement sensor measures a position in consideration of a position of the translation shaft or a signal delay when the position measurement sensor detects the object. It is characterized by that.
The invention according to claim 7 is the diameter correction for acquiring and storing the radial direction correction value of the position measurement sensor in the configuration of claim 5 or 6 as the contact sensor for the object. It further has a value acquisition means,
The position calculating unit corrects the measurement position of the position measuring sensor using the length correction value acquired by the length correction value calculating unit and the diameter correction value acquired by the diameter correction value acquiring unit. Then, the position of the object is calculated.
In order to achieve the above-mentioned object, the invention according to claim 8 uses a machine tool having three or more translation shafts, a spindle that can be rotated by mounting a tool, and a table, to the spindle. A method of measuring the position of an object fixed on the table by a position measurement sensor that can be mounted,
Using a tool sensor and a reference block provided on the tool sensor side,
A tool sensor position acquisition step of mounting a reference tool serving as a reference for the length of the tool on the spindle, and acquiring a detection position of a tip of the reference tool using the tool sensor;
A reference tool measurement position acquisition step of acquiring an arbitrary tool measurement position using the reference tool mounted on the spindle;
A position measurement sensor measurement position acquisition stage for acquiring an arbitrary sensor measurement position using the position measurement sensor mounted on the spindle;
A position measurement sensor length calculation step for obtaining a difference between the tool measurement position and the sensor measurement position and obtaining a length of the position measurement sensor based on the difference and the length of the reference tool;
A first reference block position acquisition step of measuring the position of the reference block using the position measurement sensor mounted on the spindle;
The detection position acquired in the tool sensor position acquisition stage, the position of the reference block acquired in the first reference block position acquisition stage, and the length of the position measurement sensor calculated in the position measurement sensor length calculation stage And a relative position calculating step for calculating a relative position of the reference block with respect to the detected position from the length of the reference tool;
A reference tool position acquisition step of mounting the reference tool on the spindle and acquiring a reference tool position that is a tip position of the reference tool using the tool sensor;
A second reference block position acquisition step of mounting the position measurement sensor on the spindle and measuring the position of the reference block using the position measurement sensor;
The reference tool position acquired in the reference tool position acquisition step, the position of the reference block measured in the second reference block position acquisition step, the relative position calculated in the relative position calculation step, and the reference tool A length correction value calculating step of calculating a length direction correction value of the position measurement sensor from the length of
A position measurement step of correcting the measurement position of the object measured by the position measurement sensor mounted on the spindle using the long direction correction value of the position measurement sensor calculated in the length correction value calculation step; It is characterized by performing.
According to a ninth aspect of the present invention, in the configuration of the eighth aspect, the tool sensor position acquisition stage to the relative position calculation stage are executed once, and the reference tool position acquisition stage to the position measurement stage are performed a plurality of times. It is characterized by performing.
According to a tenth aspect of the present invention, in the configuration of the eighth or ninth aspect, the position measurement is performed in the first reference block position acquisition stage, the second reference block position acquisition stage, and the position measurement stage. The position measured by the sensor is the position of the translational axis when the position measurement sensor detects that the object has been contacted.
According to an eleventh aspect of the present invention, in the configuration according to any one of the eighth to tenth aspects, the position measurement sensor is a contact-type sensor for the object, and the position measurement sensor is A diameter correction value acquisition step of acquiring a radial direction correction value is further executed, and in the position measurement step, the measurement position of the object is corrected using the diameter correction value acquired in the diameter correction value acquisition step. Features.
To achieve the above object, the invention described in claim 12 includes three or more translation axes, a spindle that can be rotated by mounting a tool, a table, and a position measurement sensor that can be mounted on the spindle. A system for measuring a position of an object fixed on the table by the position measurement sensor in a machine tool having a control device for controlling the translation shaft and the main shaft,
A reference tool serving as a reference for the length of the tool;
A tool sensor for detecting a tip position of the reference tool mounted on the spindle;
A reference block installed on the tool sensor side;
Tool sensor position acquisition means for acquiring and storing the detection position of the tip of the reference tool using the reference tool mounted on the spindle and the tool sensor;
Reference tool measurement position acquisition means for acquiring and storing an arbitrary tool measurement position using the reference tool mounted on the spindle;
Position measurement sensor measurement position acquisition means for acquiring and storing an arbitrary sensor measurement position using the position measurement sensor mounted on the spindle;
A position measurement sensor length calculation means for obtaining a difference between the tool measurement position and the sensor measurement position, calculating and storing the length of the position measurement sensor based on the difference and the length of the reference tool;
First reference block position acquisition means for measuring and storing the position of the reference block using the position measurement sensor mounted on the spindle;
The detection position acquired by the tool sensor position acquisition means, the position of the reference block acquired by the first reference block position acquisition means, and the length of the position measurement sensor calculated by the position measurement sensor length calculation means And relative position calculation means for calculating and storing the relative position of the reference block with respect to the detection position from the length of the reference tool,
Reference tool position acquisition means for acquiring and storing a reference tool position, which is a tip position of the reference tool, using the reference tool mounted on the spindle and the tool sensor;
Second reference block position acquisition means for measuring and storing the position of the reference block using the position measurement sensor mounted on the spindle;
The reference tool position acquired by the reference tool position acquisition means, the position of the reference block measured by the second reference block position acquisition means, the relative position calculated by the relative position calculation means, and the reference tool A length correction value calculating means for calculating and storing a length direction correction value of the position measurement sensor from the length of
Using the long direction correction value of the position measurement sensor calculated by the length correction value calculation means, the measurement position of the object measured by the position measurement sensor attached to the spindle is corrected, and the position of the object And a position calculating means for calculating.
According to a thirteenth aspect of the present invention, in the configuration of the twelfth aspect, the position measurement sensor measures a position in consideration of a position of the translation axis or a signal delay when the position measurement sensor detects the object. It is characterized by that.
The invention according to claim 14 is the diameter correction for acquiring and storing the radial direction correction value of the position measurement sensor in the configuration of claim 12 or 13 as the contact sensor for the object. Further comprising a value acquisition means, wherein the position calculation means uses the length correction value acquired by the length correction value calculation means and the diameter correction value acquired by the diameter correction value acquisition means. The position of the object is calculated by correcting the measurement position of the measurement sensor.

According to the present invention, the relative position between the detection position of the tool sensor and the reference block is determined in advance from the relationship between the detection position by the tool sensor and the reference tool position where the reference tool or the position measurement sensor is in contact with the reference block. By making it known, after that, the reference tool position is measured by the tool sensor, and the position of the reference block is measured by the position measurement sensor, whereby the correction value in the long direction of the position measurement sensor can be acquired. Thereby, even if the length of the position measurement sensor changes due to thermal displacement or the like, the object measurement by the position measurement sensor can be performed with high accuracy by correcting using the long direction correction value. This method does not require a measurement system using a CCD camera, and can be realized at a relatively low cost.
Particularly, in the inventions according to claims 8 to 14, since the reference block position provided on the tool sensor side is measured by the position measurement sensor, the area of the reference block is as much as the tip probe of the position measurement sensor can contact. I just need it. Therefore, the reference block can be made small, and a more compact position measurement system can be realized.
In addition, when the position measurement sensor is a contact sensor, the object can be measured with higher accuracy if the radial correction value is also acquired.

It is a schematic diagram of a machining center. It is a schematic diagram of a laser sensor. It is a schematic diagram of a touch sensor. It is a schematic diagram of a touch probe. It is a schematic diagram of the laser sensor which is an example of the tool sensor of this invention. It is a schematic diagram of the laser sensor of this invention attached to the machining center. It is a schematic diagram of the laser sensor which is an example of the tool sensor of this invention. It is a schematic diagram of the touch sensor which is an example of the tool sensor of this invention. It is a schematic diagram of the touch sensor which is an example of the tool sensor of this invention. It is a flowchart of the measurement preparation work of this invention. It is a flowchart of the position measuring method by the touch probe of this invention. It is explanatory drawing of step SR1 of the measurement preparation work of this invention. It is explanatory drawing of step SR2 of the measurement preparation work of this invention. It is explanatory drawing of step S2 of the position measuring method of this invention. It is a flowchart of the example of a change of the measurement preparation work of this invention. It is explanatory drawing of step SR1 of the example of a change of the measurement preparation work of this invention. It is explanatory drawing of step SR2 of the example of a change of the measurement preparation work of this invention. It is explanatory drawing of step SR3 of the example of a change of the measurement preparation work of this invention. It is explanatory drawing of step SR5 of the example of a change of the measurement preparation work of this invention. It is a schematic diagram of the laser sensor which is the example of a change of the tool sensor of this invention. It is a schematic diagram of the laser sensor which is the example of a change of the tool sensor of this invention. It is a schematic diagram of the touch sensor which is the example of a change of the tool sensor of this invention. It is a schematic diagram of the touch sensor which is the example of a change of the tool sensor of this invention. It is a flowchart of the position measuring method by the touch probe of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of a machining center which is an embodiment of a machine tool and has three mutually orthogonal translation axes and two mutually orthogonal rotation axes.
The main shaft 2 is a translational axis and can move with two degrees of freedom of translation relative to the bed 1 by the X axis and the Z axis orthogonal to each other. The table 3 can move with one degree of freedom of rotation with respect to the cradle 4 by a C-axis which is a rotation axis. The cradle 4 is a rotation axis and can move with one degree of freedom of rotation with respect to the trunnion 5 by an A axis orthogonal to the C axis. The trunnion 5 is a translational axis and can move with one degree of freedom of translation relative to the bed 1 by a Y-axis orthogonal to the X-axis and the Z-axis. Therefore, the main shaft 2 can move with respect to the table 3 with three translational degrees of freedom and two degrees of freedom of rotation. Each feed shaft is driven by a servo motor controlled by a numerical control device (not shown), and a workpiece is fixed to the table 3, a tool is mounted on the spindle 2 and rotated, and a relative position between the workpiece and the tool is determined. The workpiece can be processed by controlling the relative posture.

  The machine according to the present invention is not limited to a machining center, and may be a machine tool such as a lathe, a multi-task machine, or a grinding machine. Further, the number of axes is not limited to five, and only the translational axes may be three, four, or six axes. Furthermore, the mechanism is not limited to a mechanism in which the table 3 has two or more degrees of freedom of rotation by the rotating shaft, but a mechanism in which the main shaft 2 has two or more degrees of freedom of rotation, or a mechanism in which the main shaft 2 and the table 3 each have one or more degrees of freedom of rotation. Good.

FIG. 5 is a schematic diagram of a laser sensor 40 which is an example of the tool sensor of the present invention. As in FIG. 2, the laser sensor 40 includes a light emitting unit 11, a light receiving unit 12, and a base unit 13. Here, a reference block 42 is provided between the light emitting unit 11 and the light receiving unit 12. The light emitting unit 11, the light receiving unit 12, and the reference block 42 are each fixed to the base unit 13.
As shown in FIG. 6, the laser sensor 40 is attached to the trunnion 5 of the machining center shown in FIG. However, as shown in FIG. 7, the reference block 42 may be separately provided in the vicinity of the laser sensor 40.

  FIG. 8 is a schematic diagram of a touch sensor 50 which is an example of the tool sensor of the present invention. The touch sensor 50 includes a base part 51, a touch sensor part 52, and a reference block 53, and the touch sensor part 52 and the reference block 53 are fixed on the base part 51. The touch sensor 50 is attached to the trunnion 5 of the machining center in FIG. As shown in FIG. 9, the reference block 53 may be separately provided in the vicinity of the touch sensor 50.

Hereinafter, a position measurement method and a position measurement system when the laser sensor 40 is used as a tool sensor will be described (corresponding to claims 1 and 5). However, the touch sensor 50 is essentially the same except for the detection method.
First, the procedure of the measurement preparation work will be described based on the flowchart of FIG. The measurement preparation work is work performed in advance before measurement by a touch probe as a position measurement sensor described later, and may be performed in the case of deterioration or replacement of a reference tool or a laser sensor.
In step SR1, as shown in FIG. 12, the reference tool 8 is mounted on the spindle 2, and measurement is performed by the laser sensor 40. Here, the Z-axis is moved so that the reference tool 8 approaches the laser beam 14, and the point when the tip of the reference tool 8 blocks the laser beam 14 and the light receiving rate falls below the threshold or when the signal delay is taken into consideration. Get the Z-axis position. The acquired Z-axis position Zl is stored in a storage unit in a control device (not shown) (tool sensor position acquisition stage and tool sensor position acquisition means, where the control apparatus functions as each means for executing each stage of the present invention. ). The length Td of the reference tool 8 is also stored in advance in the storage unit. Here, the reference tool tip position Zl ′ (= Zl−Td) may be calculated from Zl and Td and stored.

Next, in step SR2, the position of the reference block 42 is acquired with the reference tool 8. Here, as shown in FIG. 13, in a state where the reference tool 8 is mounted on the spindle 2, the reference block 42 is contacted via the block gauge 43, the Z-axis position Zb at that time is obtained, and the thickness Hb of the block gauge 43 is obtained. The value Zb ′ (= Zb−Hb) obtained by subtracting is stored in a storage unit (not shown) in the control device (reference block position acquisition step and reference block position acquisition means). Here, the reference block upper surface position Zb ″ (= Zb−Hb−Td) may be calculated and stored using Td. The block gauge 43 may be a block having a known thickness dimension.
Next, in step SR3, the relative position dZb (= Zl−Zb ′) of the reference block 42 with respect to the detection position of the laser sensor 40 from the Z-axis position Zl stored in step SR1 and the Z-axis position Zb ′ stored in step SR2. And is stored in a storage unit in the control device (relative position calculation step and relative position calculation means). Here, the block gauge thickness Hb may also be stored in the storage unit, and dZb may be calculated from Zl, Zb, and Hb (dZb = Zl−Zb−Hb). However, when Zl ′ and Zb ″ are stored, it can be calculated by dZb = Zl′−Zb ″.

Next, a position measuring method using a touch probe in the present invention will be described based on the flowchart of FIG.
First, in step S1, as in step SR1, the reference tool 8 is mounted on the spindle 2 and measured by the laser sensor 40, and the Z-axis position Zd is stored in a storage unit (not shown) in the control device (reference tool). Position acquisition stage and reference tool position acquisition means). Note that Td may be used to store Zd ′ = Zd−Td.
Next, in step S <b> 2, the touch probe 30 is attached to the main shaft 2 as shown in FIG. 14, and the reference block 42 is measured by the touch probe 30. Here, the Z axis is moved so that the touch probe 30 approaches the reference block 42, and the Z axis position Zp at the time when the stylus at the tip of the touch probe 30 comes into contact and the trigger signal is transmitted or when the signal delay is taken into consideration. get. The acquired Z-axis position Zp is stored in a storage unit (not shown) in the control device (position measurement sensor measurement stage and measurement position acquisition means).

Next, in step S <b> 3, the length of the touch probe 30 at the time of contact, which is a correction value in the longitudinal direction of the touch probe 30, is calculated. That is, from the Zd stored in step S1, the Zp stored in step S2, the relative position dZb of the reference block 42 stored in the storage unit in the control device, and the reference tool length Td, the length A direction correction value (contact length) Tp (= Zp−Zd + dZb + Td) is obtained and stored in the storage unit (length correction value calculation step and length correction value calculation means). Here, Tp (= Zp−Zd′−dZb) may be obtained from Zd ′, Zp, and dZb.
Next, in step S <b> 4, an object (here, a workpiece on the table 3) is measured using the touch probe 30. At this time, the measurement position is corrected using the long direction correction value Tp of the touch probe 30 calculated in step S3 (position measurement stage and position calculation means).

  Thus, according to the position measurement method and position measurement system of the above embodiment, from the relationship between the detection position by the tool sensor (laser sensor 40 or touch sensor 50) and the reference tool position brought into contact with the reference block 42 in advance. By making the relative position between the detection position of the tool sensor and the reference block 42 known, thereafter, the position of the reference tool 8 is measured by the tool sensor, and the position of the reference block 42 is measured by the position measurement sensor (touch probe 30). By measuring the position, it is possible to acquire the length direction correction value (contact length) of the touch probe 30. Thereby, even if the length of the touch probe 30 changes due to thermal displacement or the like, the workpiece measurement by the touch probe 30 can be performed with high accuracy by correcting using the long direction correction value. This method does not require a measurement system using a CCD camera, and can be realized at a relatively low cost.

Next, a position measurement method and a position measurement system when the touch sensor 50 shown in FIG. 8 is used will be described (corresponding to claims 8 and 12).
First, the procedure of the measurement preparation work will be described based on the flowchart of FIG.
In step SR1, the reference tool 8 is mounted on the spindle 2 and measurement is performed by the touch sensor 50. That is, as shown in FIG. 16, the Z-axis is moved so that the reference tool 8 contacts the touch sensor unit 52, and the point when the tip of the reference tool 8 presses the touch sensor unit 52 or the signal delay is taken into consideration. Get the Z-axis position. The acquired Z-axis position Zl is stored in a storage unit (not shown) in the control device (tool sensor position acquisition step and tool sensor position acquisition means). The length Td of the reference tool 8 is also stored in advance in the storage unit.

Next, in step SR2, as a preparation for measuring the length of the touch probe, an arbitrary measurement position such as the upper surface of the table 3 with the reference tool 8 is acquired. That is, as shown in FIG. 17, with the reference tool 8 mounted on the spindle 2, it is brought into contact with an arbitrary position such as the upper surface of the table 3 via the block gauge 43, and the Z-axis position Zc at that time is obtained. A value Zc ′ (= Zc−Hb) obtained by subtracting the thickness Hb of the block gauge 43 is stored in a storage unit (not shown) in the control device (reference tool measurement position acquisition step and reference tool measurement position acquisition means). The block gauge 43 may be a block having a known thickness dimension.
Next, in step SR3, the touch probe 30 is mounted on the spindle 2, and an arbitrary measurement position such as the upper surface of the table 3 is measured as in step SR2. That is, as shown in FIG. 18, when the Z-axis is moved so that the touch probe 30 approaches an arbitrary measurement position such as the upper surface of the table 3, and the trigger signal is generated when the stylus of the touch probe 30 comes into contact or a signal delay The Z-axis position Zp at the time when the above is considered is acquired. The acquired Z-axis position Zp is stored in a storage unit (not shown) in the control device (position measurement sensor measurement position acquisition stage and position measurement sensor measurement position acquisition means).

Next, in step SR4, the length of the touch probe at the time of contact, which is the correction value in the longitudinal direction of the touch probe, is calculated. That is, a long direction correction value Tp (= Zp−Zc ′ + Td) is obtained from Zc ′ stored in step SR2, Zp stored in step SR3, and reference tool length Td, and stored in the storage unit. Store (position measurement sensor length calculation step and position measurement sensor length calculation means).
Next, in step SR5, the touch probe 30 is attached to the spindle 2, and the position Z2 of the reference block 53 is measured. That is, as shown in FIG. 19, the Z axis is moved so that the touch probe 30 approaches the reference block 53, and the trigger signal is transmitted when the stylus of the touch probe 30 comes into contact or when the signal delay is taken into consideration. The Z-axis position Z2 is acquired (first reference block position acquisition step and first reference block position acquisition means).
Next, in step SR6, a distance dZb between the contact position of the touch sensor 50 and the reference block 53 is calculated. Here, the contact position Zl between the reference tool 8 and the touch sensor 50 obtained at step SR1, the contact position Z2 between the touch probe 30 and the reference block 53 obtained at step SR5, and the longitudinal correction value Tp of the touch probe 30 The distance dZb (= Z2 + Tp− (Zl + Td)) between the contact position of the touch sensor 50 and the reference block 53 is obtained from the reference tool length Td and stored in the storage unit (relative position calculation stage and relative position calculation). means).

The flow of measurement by the touch probe in this case is the same as the flowchart of FIG.
First, in step S1, as in step SR1, the reference tool 8 is mounted on the spindle 2, measurement is performed by the touch sensor 50, and the Z-axis position Zl ′ is stored in a storage unit (not shown) in the control device (reference). Tool position acquisition stage and reference tool position acquisition means).
Next, in step S2, as in step SR5, the touch probe 30 is mounted on the spindle 2, the reference block 53 is measured by the touch probe 30, and the Z-axis position Z2 ′ is not shown in the storage unit in the control device. (Second reference block position acquisition step and second reference block position acquisition means).
Next, in step S <b> 3, the length of the touch probe 30 at the time of contact, which is a correction value in the longitudinal direction of the touch probe 30, is calculated. That is, the distance between Zl ′ stored in step S1, Z2 ′ stored in step S2, and the contact position of the touch sensor 50 stored in the storage unit in the control device and the reference block 53. A long-direction correction value Tp ′ (= Zl′−Z2 ′ + dZb + Td) is obtained from dZb and the reference tool length Td and stored in the storage unit (length correction value calculation step and length correction value calculation means).
Next, in step S <b> 4, the object is measured using the touch probe 30. At this time, the acquisition position is corrected using the long direction correction value Tp ′ of the touch probe 30 calculated in step S3 (position measurement stage and position measurement means).

As described above, also in the position measurement method and the position measurement system of the above embodiment, the detection position by the touch sensor 50, the reference tool position where the touch probe 30 is brought into contact with the reference block 53, and the length of the touch probe 30 in advance. By making the relative position between the detection position of the tool sensor and the reference block 53 known from the relationship with the reference tool 8, the position of the reference tool 8 is measured with the tool sensor and the reference with the touch probe 30. By measuring the position of the block 53, the length direction correction value (contact length) of the touch probe 30 can be acquired. Thereby, even if the length of the touch probe 30 changes due to thermal displacement or the like, the workpiece measurement by the touch probe 30 can be performed with high accuracy by correcting using the long direction correction value.
In particular, since the reference block position provided in the touch sensor 50 is measured by the touch probe 30, the area of the reference block 53 may be as much as the stylus of the touch probe 30 can touch. Therefore, the reference block 53 can be made small, and a more compact position measurement system can be realized. It should be noted that the method and system of this embodiment can be similarly performed with the touch sensor 50 of FIG.

Another embodiment of the present invention will be described with reference to the drawings.
FIG. 20 is a schematic view of another embodiment of the laser sensor 40 of the present invention. The laser sensor 40 includes a reference sphere 44 in addition to the light emitting unit 11, the light receiving unit 12, the base unit 13, and the reference block 42, as in FIG. 5. The reference block 42 and the reference sphere 44 are fixed to the base portion 13. As shown in FIG. 21, the reference block 42 and / or the reference sphere 44 may be separately provided in the vicinity of the base portion 13.
FIG. 22 is a schematic view of another form of the touch sensor 50 which is an example of the tool sensor of the present invention. The touch sensor 50 includes a reference sphere 54 in addition to the base 51, the touch sensor 52, and the reference block 53, as in FIG. The touch sensor unit 52, the reference block 53, and the reference sphere 54 are fixed to the base unit 51. 23, the reference block 53 and / or the reference sphere 54 may be separately provided in the vicinity of the base portion 51.

Hereinafter, a position measuring method when the laser sensor 40 is used as a tool sensor will be described. However, the touch sensor 50 is essentially the same except for the detection method.
The flow of measurement by the touch probe in the present invention will be described based on the flowchart of FIG. The measurement preparation work is the same as that shown in the flowchart of FIG. 10 to obtain the relative position dZb.
Steps S1 to S3 are the same as those in FIG.
In step S5, the diameter correction value of the touch probe 30 is acquired. Specifically, first, the touch probe 30 measures a total of four vertices of the X axis plus / minus direction and the Y axis plus / minus direction on the same plane in the horizontal direction of the reference sphere 44 (the radial direction of the touch probe 30). . At this time, the spindle 2 is determined so that the contact points of the touch probe 30 are the same. The obtained average value of the X-axis position and the average value of the Y-axis position are the X and Y coordinate values of the sphere center, respectively. The four vertices are measured again for the center positions X and Y. The X-axis plus direction correction value Rxp, X-axis minus direction correction value Rxm, Y-axis plus direction correction value Ryp, and Y-axis minus direction correction value Rym of the touch probe are calculated from the difference between the obtained four positions and the center position ( Diameter correction value acquisition stage and diameter correction value acquisition means).

Next, in step S <b> 6, the object is measured using the touch probe 30. At this time, the acquisition position is corrected using the long direction correction value Tp of the touch probe 30 calculated in step S3 and the radial direction correction values Rxp, Rxm, Ryp, Rym of the touch probe 30 calculated in step S5.
Thus, since the correction value in the radial direction of the touch probe 30 is also acquired here, the position of the workpiece can be measured with higher accuracy.

In the above embodiment, the touch probe is used as the position measurement sensor. However, the present invention can also be applied to the case where the position measurement sensor employs a non-contact sensor such as a laser displacement sensor to measure the position of a workpiece or the like. . In this case, the length correction value is not the length at the time of contact, but the apparent distance between the object at the time of measurement and the non-contact sensor.
In the above embodiment, when the reference block position is acquired, the reference tool is indirectly brought into contact with the reference block using a block gauge. However, the reference tool may be directly brought into contact with the reference block without the block gauge. .
Furthermore, in the above embodiment, the process from the tool sensor position acquisition stage to the position measurement stage is executed once, but the process from the tool sensor position acquisition stage to the relative position calculation stage is executed once, from the reference tool position acquisition stage to the position measurement stage. Up to a plurality of times may be executed.

  1 .... bed, 2 .... main shaft, 3 .... table, 4 .... cradle, 5 .... trunnion, 8 .... reference tool, 9 .... tool, 11 .... light emitting part, 12 .... light receiving part, 13 ....・ Base part, 14 ・ ・ Laser beam, 30 ・ ・ Touch probe, 31 ・ ・ Workpiece, 40 ・ ・ Laser sensor, 41 ・ ・ Sensor mount, 42 ・ ・ Reference block, 43 ・ ・ Block gauge, 44 ・ ・Reference sphere, 50 ·· Touch sensor, 51 ·· Base portion, 52 ·· Touch sensor portion, 53 ·· Reference block, 54 ·· Reference sphere.

Claims (14)

An object fixed on the table by a position measuring sensor that can be mounted on the spindle using a machine tool having three or more translation axes, a spindle that can be rotated by mounting a tool, and a table. A method for measuring the position of
A tool sensor position acquisition step of mounting a reference tool serving as a reference for the length of the tool on the spindle and acquiring a detection position of the tip of the reference tool using a tool sensor;
A reference block position obtaining step for obtaining the position of the translation shaft when the reference tool mounted on the spindle is brought into direct or indirect contact with a reference block provided on the tool sensor side;
A relative position calculation step of calculating a relative position of the reference block with respect to the detection position from the detection position acquired in the tool sensor position acquisition step and the position of the translation axis acquired in the reference block position acquisition step;
A reference tool position acquisition step of mounting the reference tool on the spindle and acquiring a reference tool position that is a tip position of the reference tool using the tool sensor;
A position measurement sensor measurement step of mounting the position measurement sensor on the spindle and measuring the position of the reference block using the position measurement sensor;
The reference tool position acquired in the reference tool position acquisition step, the position of the reference block measured in the position measurement sensor measurement step, the relative position calculated in the relative position calculation step, and the length of the reference tool From the long correction value calculation step of calculating the long direction correction value of the position measurement sensor,
A position measurement step for correcting the measurement position of the object measured by the position measurement sensor mounted on the spindle, using the long direction correction value of the position measurement sensor calculated in the length correction value calculation step;
A method for measuring the position of an object in a machine tool, characterized in that From the tool sensor position acquisition stage to the relative position calculation stage is executed once,
The method for measuring a position of an object in a machine tool according to claim 1, wherein the process from the reference tool position acquisition stage to the position measurement stage is executed a plurality of times.   The position measured by the position measurement sensor in the position measurement sensor measurement stage and the position measurement stage is a position of the translation axis when it is detected that the position measurement sensor is in contact with an object. The position measuring method of the target object in the machine tool according to claim 1 or 2.   Using the position measurement sensor as a contact sensor for the object, further executing a diameter correction value acquisition step of acquiring a radial direction correction value of the position measurement sensor before execution of the position measurement step; The position of the object in the machine tool according to claim 1, wherein the measurement position of the object is corrected using the diameter correction value acquired in the diameter correction value acquisition step. Measurement method. 3 or more translation axes, a spindle that can be rotated by mounting a tool, a table, a position measurement sensor that can be mounted on the spindle, and a controller that controls the translation axis and the spindle. In a machine tool, a system for measuring the position of an object fixed on the table by the position measurement sensor,
A reference tool serving as a reference for the length of the tool;
A tool sensor for detecting a tip position of the reference tool mounted on the spindle;
A reference block installed on the tool sensor side;
Tool sensor position acquisition means for moving the reference tool mounted on the spindle by the translation shaft and acquiring and storing the detection position of the tip of the reference tool using the tool sensor;
Reference block position acquisition for acquiring and storing the position of the translation axis at the time of contact with the reference block by moving the reference tool mounted on the spindle by the translation axis to directly or indirectly contact the reference block Means,
A relative position for calculating and storing a relative position of the reference block with respect to the detection position from the detection position acquired by the tool sensor position acquisition means and the position of the translation axis acquired by the reference block position acquisition means. A calculation means;
A reference tool position acquisition means for moving the reference tool mounted on the spindle by the translation shaft and acquiring and storing a reference tool position which is a tip position of the reference tool using the tool sensor;
Measurement position acquisition means for measuring and storing the position of the reference block with the position measurement sensor mounted on the spindle;
The reference tool position acquired by the reference tool position acquisition means, the position of the reference block acquired by the measurement position acquisition means, the relative position acquired by the relative position calculation means, and the reference tool A length correction value calculating means for calculating and storing a length direction correction value of the position measurement sensor from the length;
Position calculation means for correcting the measurement position by the position measurement sensor using the length correction value stored in the length correction value calculation means, and calculating the position of the object;
A system for measuring a position of an object in a machine tool.   6. The object in a machine tool according to claim 5, wherein the position measurement sensor measures a position in consideration of a position of the translation axis or a signal delay when the position measurement sensor detects the object. Position measurement system. The position measurement sensor as a contact sensor to the object further includes a diameter correction value acquisition means for acquiring and storing a radial direction correction value of the position measurement sensor,
The position calculating unit corrects the measurement position of the position measuring sensor using the length correction value acquired by the length correction value calculating unit and the diameter correction value acquired by the diameter correction value acquiring unit. The position measurement system for the object in the machine tool according to claim 5, wherein the position of the object is calculated. An object fixed on the table by a position measuring sensor that can be mounted on the spindle using a machine tool having three or more translation axes, a spindle that can be rotated by mounting a tool, and a table. A method for measuring the position of
Using a tool sensor and a reference block provided on the tool sensor side,
A tool sensor position acquisition step of mounting a reference tool serving as a reference for the length of the tool on the spindle, and acquiring a detection position of a tip of the reference tool using the tool sensor;
A reference tool measurement position acquisition step of acquiring an arbitrary tool measurement position using the reference tool mounted on the spindle;
A position measurement sensor measurement position acquisition stage for acquiring an arbitrary sensor measurement position using the position measurement sensor mounted on the spindle;
A position measurement sensor length calculation step for obtaining a difference between the tool measurement position and the sensor measurement position and obtaining a length of the position measurement sensor based on the difference and the length of the reference tool;
A first reference block position acquisition step of measuring the position of the reference block using the position measurement sensor mounted on the spindle;
The detection position acquired in the tool sensor position acquisition stage, the position of the reference block acquired in the first reference block position acquisition stage, and the length of the position measurement sensor calculated in the position measurement sensor length calculation stage And a relative position calculating step for calculating a relative position of the reference block with respect to the detected position from the length of the reference tool;
A reference tool position acquisition step of mounting the reference tool on the spindle and acquiring a reference tool position that is a tip position of the reference tool using the tool sensor;
A second reference block position acquisition step of mounting the position measurement sensor on the spindle and measuring the position of the reference block using the position measurement sensor;
The reference tool position acquired in the reference tool position acquisition step, the position of the reference block measured in the second reference block position acquisition step, the relative position calculated in the relative position calculation step, and the reference tool A length correction value calculating step of calculating a length direction correction value of the position measurement sensor from the length of
A position measurement step for correcting the measurement position of the object measured by the position measurement sensor mounted on the spindle, using the long direction correction value of the position measurement sensor calculated in the length correction value calculation step;
A method for measuring the position of an object in a machine tool, characterized in that The tool sensor position acquisition stage to the relative position calculation stage are executed once,
The method of measuring a position of an object in a machine tool according to claim 8, wherein the steps from the reference tool position acquisition step to the position measurement step are executed a plurality of times.   In the first reference block position acquisition stage, the second reference block position acquisition stage, and the position measurement stage, the position measured by the position measurement sensor is in contact with the object. The position measuring method of an object in a machine tool according to claim 8 or 9, wherein the position of the translational axis is detected.   Using the position measurement sensor as a contact sensor for the object, further executing a diameter correction value acquisition step of acquiring a radial direction correction value of the position measurement sensor before execution of the position measurement step; The position of the object in the machine tool according to claim 8, wherein the measurement position of the object is corrected using the diameter correction value acquired in the diameter correction value acquisition step. Measurement method. 3 or more translation axes, a spindle that can be rotated by mounting a tool, a table, a position measurement sensor that can be mounted on the spindle, and a controller that controls the translation axis and the spindle. In a machine tool, a system for measuring the position of an object fixed on the table by the position measurement sensor,
A reference tool serving as a reference for the length of the tool;
A tool sensor for detecting a tip position of the reference tool mounted on the spindle;
A reference block installed on the tool sensor side;
Tool sensor position acquisition means for acquiring and storing the detection position of the tip of the reference tool using the reference tool mounted on the spindle and the tool sensor;
Reference tool measurement position acquisition means for acquiring and storing an arbitrary tool measurement position using the reference tool mounted on the spindle;
Position measurement sensor measurement position acquisition means for acquiring and storing an arbitrary sensor measurement position using the position measurement sensor mounted on the spindle;
A position measurement sensor length calculation means for obtaining a difference between the tool measurement position and the sensor measurement position, calculating and storing the length of the position measurement sensor based on the difference and the length of the reference tool;
First reference block position acquisition means for measuring and storing the position of the reference block using the position measurement sensor mounted on the spindle;
The detection position acquired by the tool sensor position acquisition means, the position of the reference block acquired by the first reference block position acquisition means, and the length of the position measurement sensor calculated by the position measurement sensor length calculation means And relative position calculation means for calculating and storing the relative position of the reference block with respect to the detection position from the length of the reference tool,
Reference tool position acquisition means for acquiring and storing a reference tool position, which is a tip position of the reference tool, using the reference tool mounted on the spindle and the tool sensor;
Second reference block position acquisition means for measuring and storing the position of the reference block using the position measurement sensor mounted on the spindle;
The reference tool position acquired by the reference tool position acquisition means, the position of the reference block measured by the second reference block position acquisition means, the relative position calculated by the relative position calculation means, and the reference tool A length correction value calculating means for calculating and storing a length direction correction value of the position measurement sensor from the length of
Using the long direction correction value of the position measurement sensor calculated by the length correction value calculation means, the measurement position of the object measured by the position measurement sensor attached to the spindle is corrected, and the position of the object Position calculating means for calculating
A system for measuring a position of an object in a machine tool.   The object in a machine tool according to claim 12, wherein the position measurement sensor measures a position in consideration of a position of the translation axis or a signal delay when the position measurement sensor detects the object. Position measurement system. The position measurement sensor as a contact sensor to the object further includes a diameter correction value acquisition means for acquiring and storing a radial direction correction value of the position measurement sensor,
The position calculating unit corrects the measurement position of the position measuring sensor using the length correction value acquired by the length correction value calculating unit and the diameter correction value acquired by the diameter correction value acquiring unit. The position measurement system for an object in a machine tool according to claim 12 or 13, wherein the position of the object is calculated.

Images