JP6013139B2 - Tool length measuring method and machine tool - Google Patents

Description

  The present invention relates to a tool length measuring method and a machine tool. Specifically, the present invention relates to a tool length measuring method and a machine tool that can measure the tool length of a tool based on a workpiece.

2. Description of the Related Art Conventionally, a machine tool for cutting a workpiece by attaching a tool having a cutter to a main shaft and rotating the tool has been used.
In such machine tools, the rigidity of the support structure is improved in order to improve the machining accuracy, and the operation accuracy of the X, Y, and Z axis moving mechanisms that move the main shaft is improved. .

In the machine tool described above, the operation accuracy of each axis moving mechanism affects the position accuracy of the spindle in the coordinate system of the machine tool.
However, it is the cutting edge of the tool tip that is the machining part that directly affects the machining accuracy of the workpiece. For example, if the mounting condition of the tool with respect to the spindle is unstable, or the distance to the tool tip (tool length) changes due to wear of the cutting edge, etc., these become error factors and improve the position accuracy of the spindle. However, the positional accuracy at the tool tip is not sufficiently improved.

As a method to eliminate such errors due to tool length fluctuations, the tool length of the tool mounted on the spindle is measured prior to machining, and the difference between the actual measured value at the tool tip and the reference value is obtained to determine the machining operation. Sometimes, the above-described difference is corrected.
As a method for measuring such a tool length, for example, a technique described in Patent Document 1 is known.

  In Patent Document 1, when a workpiece is placed on a table and cutting is performed with a tool attached to the spindle, a measurement touch sensor is placed at a location different from the workpiece on the table prior to the machining. Then, the spindle on which the tool used for machining is mounted is moved, and the tip of the tool is brought into contact with the touch sensor. When the touch of the tool is detected by the touch sensor, the current tool length of the spindle can be acquired from the spindle coordinates of the machine tool at that time.

JP 2001-300836 A

By the way, in the above-described tool length measurement of Patent Document 1, the tool is brought into contact with a touch sensor placed at a position different from the work on the table, and the coordinate position of the acquired tool tip is based on the table surface. It is a thing.
However, when cutting a workpiece, the depth of cut is specified based on the workpiece upper surface (machined surface) directed to the main axis among the workpiece surfaces to be machined. Therefore, whether the reference is the table surface or the workpiece upper surface. An error may occur depending on whether or not.
In particular, when placing a workpiece on the table surface, the distance from the table surface to the workpiece upper surface may vary depending on the structure and setting conditions for fixing the workpiece to the table. May not be obtained.

  An object of the present invention is to provide a tool length measuring method and a machine tool capable of machining a workpiece with high accuracy even if the fixed state of the workpiece with respect to the table fluctuates.

In the present invention, the tool length measuring instrument is installed not on the table surface but on the workpiece surface. When the tool length measuring instrument is installed at an arbitrary position on the workpiece upper surface, the control device of the machine tool becomes in a state where the position of the tool length measuring instrument (coordinate position along the workpiece upper surface) is unknown.
Therefore, in the present invention, the coordinate position on the workpiece upper surface of the tool length measuring instrument is measured by a separate position detection device and is taken into the machine tool.

  Specifically, the tool length measuring method of the present invention is a tool length measuring method for measuring a tool length of a tool that is mounted on a spindle of a machine tool and processes a workpiece placed on the table of the machine tool. A workpiece installation step of installing a workpiece on the table, a touch sensor installation step of installing on the upper surface of the workpiece a touch sensor capable of contacting the tip of the tool and detecting the tip contact of the tool, A touch sensor coordinate position detecting step for detecting a coordinate position of the touch sensor installed on the upper surface by a position detection device, and relative movement between the table and the spindle so that the tool is positioned at the detected coordinate position And a tool length measuring step of measuring the tool length of the tool by bringing the tip of the tool into contact with the touch sensor.

According to such a configuration, since the work is placed on the table and the touch sensor is placed on the upper surface of the work, the tool length is measured by bringing the tip of the tool into contact with the touch sensor. The tool length of the tool can be measured on the basis of the upper surface, that is, the work surface of the workpiece. Therefore, even if the fixed state of the workpiece with respect to the table fluctuates, the tool length is measured based on the machining surface of the workpiece, so that the workpiece can be machined with high accuracy.
In particular, in the present invention, when the operator places the touch sensor at an arbitrary position on the upper surface of the workpiece, the coordinate position of the touch sensor is detected by the position detection device, and the table is set so that the tool is positioned at the detected coordinate position. Since the tool length measurement step is executed after the relative movement between the spindle and the spindle, the tool length can be efficiently measured without placing a burden on the operator.

In the tool length measurement method of the present invention, it is preferable that the touch sensor coordinate position detection step detects a coordinate position of the touch sensor using a non-contact type position detection device.
According to such a configuration, since the coordinate position of the touch sensor is detected by the non-contact type position detection device, for example, the coordinate position of the touch sensor is obtained from the image of the touch sensor imaged using the camera. Since the method or the method of calculating the coordinate position of the touch sensor using a laser is used, the coordinate position of the touch sensor can be obtained in a short time and with high accuracy.

In the tool length measurement method of the present invention, the touch sensor is installed on the upper surface of the work until the work is finished, and the tool length measurement step is performed at any time before and during the work of the work. It is preferable to execute.
According to such a configuration, the touch sensor is installed on the upper surface of the work until the work is finished. Therefore, the tool length measurement process is executed at any time before and during the work of the work. be able to. Therefore, highly accurate machining can be performed by executing the tool length measurement process at a plurality of times during machining, for example, according to machining conditions such as heavy machining.

The machine tool of the present invention is a machine tool comprising a table for placing a workpiece, a spindle on which a tool for machining the workpiece is mounted, and a relative movement mechanism for relatively moving the table and the spindle. A touch sensor installed on the upper surface of the workpiece, capable of being contacted by the tip of the tool and capable of detecting contact of the tip of the tool, a position detecting device for detecting a coordinate position of the touch sensor, and a control device; The apparatus moves the table and the spindle relative to each other by driving the relative movement mechanism so that the tool is positioned at the coordinate position detected by the position detection device, and then moves the tip of the tool to the touch sensor. Relative movement command means for making contact with the tool, and tool length measuring means for measuring the tool length of the tool based on a contact detection signal from the touch sensor. There, characterized in that.
According to such a configuration, the same effect as the above-described tool length measuring method can be expected.

The front view of the machine tool which shows one Embodiment of this invention. The figure which shows the tool holder used by embodiment same as the above. The front view of the machine tool of the state which mounted | wore the main axis | shaft with the camera in embodiment same as the above. The block diagram which shows the control system of embodiment same as the above. The figure which shows the image imaged with the camera in embodiment same as the above. The figure which shows a tool length measurement process in embodiment same as the above. The figure which shows the outline | summary of the non-contact position detection apparatus used in other embodiment of this invention.

Embodiments of the present invention will be described with reference to the drawings.
<Description of machine tool body>
FIG. 1 is a front view showing an embodiment of a machine tool of the present invention.
The machine tool includes a machine tool main body 10 and an NC device 30 as a control device that drives and controls the machine tool main body 10 according to a machining program.

  The machine tool main body 10 includes a base 11, a table 12 provided on the base 11 so as to be movable in the front-rear direction (X-axis direction), and a work 12 placed on the upper surface thereof, and a pair standing upright on both sides of the base 11 Columns 13A, 13B, a cross rail 14 spanned between the upper portions of both columns 13A, 13B, and a saddle 16 provided so as to be movable in the left-right direction (Y-axis direction) along the cross rail 14. A ram 17 provided on the saddle 16 so as to be movable up and down (Z-axis direction), a main shaft 18 rotatably accommodated in the ram 17, and a drive motor 19 for rotating the main shaft 18. Prepare. The X axis, the Y axis, and the Z axis are orthogonal to each other.

  The base 11 is provided with an X-axis moving mechanism 21 that moves the table 12 in the X-axis direction, and the cross rail 14 is provided with a Y-axis moving mechanism 22 that moves the saddle 16 in the Y-axis direction. Is provided with a Z-axis moving mechanism 23 for moving the ram 17 in the Z-axis direction. The X-axis moving mechanism 21, the Y-axis moving mechanism 22, and the Z-axis moving mechanism 23 constitute a control axis. From these three control axes, the table 12 (work W) and the main shaft 18 are moved in a three-dimensional direction. A three-dimensional relative movement mechanism is provided for relative movement.

A tool storage device 25 and an ATC (automatic tool changer) 26 are provided on one column 13A side of the pair of columns 13A and 13B.
The tool storage device 25 stores a plurality of different types of tool holders (the tool holder 1 on which a tool is mounted).
An ATC (automatic tool changer) 26 exchanges tools between the tool storage device 25 and the main shaft 18. For example, when the main shaft 18 is moved closer to the left end in FIG. 1 by driving the Y-axis moving mechanism 22, the tool holder 1 in use attached to the main shaft 18 and the tool holder 1 in the tool storage device 25. Replace automatically.

As shown in FIG. 2, the tool holder 1 has a tapered shank portion 2 attached to the main shaft 18, and a tool holding portion 4 formed with respect to the tapered shank portion 2 via an intermediate flange portion 3.
The taper shank portion 2 is provided with a pull stud 5 that is pulled up by a clamp claw (not shown) provided in the main shaft 18 when the tool holder 1 is mounted on the main shaft 18. A tool T such as a drill is attached to the tool holding unit 4. Here, before or during machining, the tool length of the tool T, that is, the length from the tip of the tool holding unit 4 to the tip of the tool T is registered as the tool length TL.

As shown in FIG. 3, a CCD camera C is attached to the main shaft 18 instead of the tool holder 1.
The CCD camera C images the touch sensor 6 installed on the upper surface, which is the processing surface of the workpiece W, directly above the table 12. The touch sensor 6 has a structure including a contact portion 6A that contacts the tip of the tool T, and a contact detection portion 6B that detects that the tip of the tool T contacts the contact portion 6A and emits a contact detection signal wirelessly.
The image of the touch sensor 6 picked up by the CCD camera C is taken into the NC device 30, where it is image processed and the coordinate position of the touch sensor 6 is calculated.

<Description of NC device and its peripheral devices>
As shown in FIG. 4, the NC device 30 includes an X-axis moving mechanism 21, a Y-axis moving mechanism 22, a Z-axis moving mechanism 23, an X-axis displacement detector 27, a Y-axis displacement detector 28, and a Z-axis displacement detector. 29, a drive motor 19, an ATC 26, a touch sensor 6, a CCD camera C attached to the spindle 18 in place of the tool holder 1, an input device 31, a display 32, a printer 33, a memory 34, and the like are connected. In addition to the machining program for driving the X-axis moving mechanism 21, the Y-axis moving mechanism 22, the Z-axis moving mechanism 23, the drive motor 19, the ATC 26, and the like, the memory 34 is provided with storage areas for various calculations.

  The NC device 30 has a function of driving the X-axis moving mechanism 21, the Y-axis moving mechanism 22, the Z-axis moving mechanism 23, the drive motor 19, the ATC 26, and the like according to the machining program, and a touch sensor imaged by the CCD camera C. 6 and the coordinate position calculating means for calculating the coordinate position of the touch sensor 6 and the table 12 and the spindle so that the tool T is positioned at the coordinate position of the touch sensor 6 calculated by the coordinate position calculating means. And a relative movement command means for bringing the tip of the tool T into contact with the touch sensor 6, and a tool length measuring means for measuring the tool length of the tool T based on a contact detection signal from the touch sensor 6. It is comprised including. Here, a non-contact type position detection device that detects the coordinate position of the touch sensor 6 in a non-contact manner is constituted by the CCD camera C and the coordinate position calculation means.

<Tool length measurement>
First, before machining the workpiece W, the tool length TL of the tool T to be used is measured, and this tool length TL is registered.
For this purpose, as shown in FIG. 3, after the operator installs the workpiece W on the upper surface of the table 12 (work installation step), the touch sensor 6 is placed at an arbitrary position on the upper surface, which is the processed surface of the workpiece W. Install (touch sensor installation process). At this time, the upper surface of the workpiece W on which the touch sensor 6 is installed is preferably a horizontal surface having a width that allows the touch sensor 6 to be installed, and is preferably the same surface as the surface to be processed.

  In addition, after the CCD camera C is mounted on the tip of the spindle 18, the touch sensor 6 installed on the upper surface of the workpiece W is imaged by the CCD camera C. Then, the captured image of the touch sensor 6 is sent to the NC device 30. As shown in FIG. 5, the NC device 30 processes the image of the touch sensor 6 to obtain the coordinate position (x ′, y ′) of the touch sensor 6 from the machine origin O. For example, a planar image of the touch sensor 6 is registered in advance, and the registered image of the touch sensor 6 is applied from images captured by the CCD camera C, and the center coordinates of the image at the corresponding position are calculated. Thus, the coordinate position (x ′, y ′) of the touch sensor 6 is obtained.

  When the coordinate position of the touch sensor 6 is calculated, the NC device 30 drives the relative movement mechanism so that the tool T is positioned at the detected coordinate position and moves the table 12 and the spindle 18 relatively. The tip of the tool T is brought into contact with the touch sensor 6. That is, after driving the X-axis moving mechanism 21, Y-axis moving mechanism 22, and Z-axis moving mechanism 23 to move the table 12 and the main shaft 18 relative to each other, the tip of the tool T is touched as shown in FIG. Contact the sensor 6.

  When the tip of the tool T comes into contact with the touch sensor 6, a contact detection signal is given from the touch sensor 6 to the NC device 30. Then, the NC device 30 takes in the detected value of the Z-axis displacement detector 29 and obtains the tool length TL of the tool T from this detected value. That is, the tool length TL with respect to the upper surface of the workpiece W is measured. After that, the tool length TL is registered in a predetermined area of the memory 34 and used during machining.

<Workpiece processing>
In machining the workpiece W, the X-axis movement mechanism 21, the Y-axis movement mechanism 22, and the Z-axis movement mechanism 23 are driven according to the machining program. Thereby, the workpiece W is machined by the tool T while the table 12 and the spindle 18 are relatively moved.
At this time, as a result of controlling the movement of the main shaft 18 in the Z-axis direction based on the registered tool length TL, the depth of the hole can be machined with high accuracy. That is, since the tool length TL is measured and registered with respect to the upper surface of the workpiece W, it is possible to control with high accuracy when the tip of the tool T is positioned on the upper surface of the workpiece W. Can be processed.

<Effect of embodiment>
According to the present embodiment, after the work W is set on the table 12 and the touch sensor 6 is set on the upper surface of the work W, the tip of the tool T is brought into contact with the touch sensor 6 to measure the tool length TL. Therefore, the tool length TL of the tool T can be measured with reference to the upper surface of the workpiece W, that is, the machining surface of the workpiece W. Therefore, even if the fixed state of the workpiece W with respect to the table 12 varies, the workpiece W can be processed with high accuracy.

Further, if the operator places the touch sensor 6 at an arbitrary position on the upper surface of the workpiece W, an image of the touch sensor 6 is picked up by the CCD camera C, and this image is processed to detect the coordinate position of the touch sensor 6. After the table 12 and the spindle 18 are moved relative to each other so that the tool T is located at the detected coordinate position, the tool length measurement process is executed, so that the tool length can be adjusted without imposing a burden on the operator. Measurements can be performed efficiently.
In particular, since the coordinate position of the touch sensor 6 is detected using a non-contact type position detection device using the CCD camera C, the coordinate position of the touch sensor 6 can be obtained in a short time and with high accuracy. it can.

Further, since the touch sensor 6 is installed on the upper surface of the workpiece W until the machining of the workpiece W is completed, the tool length measurement process can be executed at any time before and during the machining of the workpiece W. it can.
Therefore, highly accurate machining can be performed by executing the tool length measurement process at a plurality of times during machining, for example, according to machining conditions such as heavy machining.

  In the above embodiment, the CCD camera C is attached to the tip of the main shaft 18, but the attachment position of the CCD camera C is not limited to the main shaft 18. For example, as shown by a chain line in FIG. 3, the saddle 16 may be fixed to the lower surface, or the cross rail 14 may be fixed to the lower surface. In short, it may be anywhere as long as the entire upper surface of the work W on which the table 12 is placed can be imaged.

<Modification>
The present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  In the above embodiment, the CCD camera C is used to capture an image of the touch sensor 6 and the coordinate position of the touch sensor 6 is calculated from the image of the touch sensor 6. May be one in which the coordinate position of the touch sensor 6 is calculated using a laser.

As a non-contact type position detection device using a laser, for example, coordinate position detection disclosed in Japanese Patent Application Laid-Open No. 2011-14107 can be used.
This is because, as shown in FIG. 7, the retroreflector 40 that is provided in the touch sensor 6 and returns reflected light parallel to the incident light, and at least two positions different from the touch sensor 6 (two positions on the table 12). Two optical units 41A and 41B installed in the.
Each of the optical units 41A and 41B includes an irradiation light scanning unit 42 that scans the irradiation light horizontally on the upper surface of the workpiece W at a predetermined scanning angle, and a light receiving sensor unit that receives the reflected light reflected by the retroreflector 40. 43.

When the irradiation light is scanned from the irradiation light scanning unit 42 of each of the optical units 41A and 41B, the irradiation light is reflected in parallel with the incident light by the retroreflector 40 provided in the touch sensor 6, and the light receiving sensor unit 43. Is received.
In each of the optical units 41A and 41B, if the light receiving timing of the reflected light of the maximum light receiving level is detected among the reflected light received by the light receiving sensor unit 43, and the scanning angle of the irradiation light corresponding to this light receiving timing is detected, the triangle is obtained. From the principle of surveying, the coordinate position of the touch sensor 6 can be calculated from the scanning angles θ1 and θ2 of the irradiation light and the installation interval L between the optical units 41A and 41B.
In addition, when the height dimension of the workpiece W changes, the installation table 44 on which both the optical units 41A and 41B are installed is configured such that the height can be adjusted, and the height of the installation table 44 is automatically set according to the height of the workpiece W. You may comprise so that it can adjust automatically.

In addition, the position detection device is not limited to a laser, and may be another type of position detection device.
For example, a GPS (Global Positioning System) may be mounted in the touch sensor 6 to measure the position of the touch sensor 6.

  In the above embodiment, the touch sensor 6 is installed on the upper surface of the workpiece W until the machining is completed. However, the installation position of the touch sensor 6 may be changed depending on the machining status of the workpiece W. The coordinate position of the touch sensor 6 may be detected by the device and the tool length measurement may be executed.

  In the above embodiment, the table 12 is described as an example of a machine tool that can move in the X-axis direction and the main shaft 18 can move in the Y-axis direction and the Z-axis direction. Any machine tool may be used as long as the machine tool is structured to move relative to each other.

  INDUSTRIAL APPLICABILITY The present invention can be used for a machine tool that performs cutting of a workpiece by mounting and rotating a tool having a cutter on a main shaft.

6 ... Touch sensor,
12 ... table,
18 ... Spindle,
21 ... X-axis movement mechanism (relative movement mechanism),
22 ... Y-axis movement mechanism (relative movement mechanism),
23 ... Z-axis movement mechanism (relative movement mechanism),
30 ... NC device (control device),
T ... Tool,
TL ... Tool length,
W ... Work.

Claims (4)

A tool length measuring method for measuring a tool length of a tool that is mounted on a spindle of a machine tool and processes a workpiece placed on a table of the machine tool,
A workpiece installation step of installing a workpiece on the table;
A touch sensor installation step of installing a touch sensor on the upper surface of the workpiece, the touch sensor capable of contacting the tip of the tool and capable of detecting the tip contact of the tool;
A touch sensor coordinate position detection step of detecting a coordinate position of the touch sensor installed on the upper surface of the workpiece by a position detection device;
A tool length for measuring the tool length of the tool by moving the table and the spindle relative to each other so that the tool is positioned at the detected coordinate position and then bringing the tip of the tool into contact with the touch sensor. Measuring process;
A tool length measuring method comprising: In the tool length measuring method according to claim 1,
In the touch sensor coordinate position detection step, the coordinate position of the sensor is detected by using a non-contact type position detection device. In the tool length measuring method according to claim 1 or 2,
The touch sensor is installed on the upper surface of the workpiece until the processing of the workpiece is completed,
Performing the tool length measuring step at any time before and during machining of the workpiece;
The tool length measuring method characterized by the above-mentioned. In a machine tool comprising a table for placing a workpiece, a spindle on which a tool for machining the workpiece is mounted, and a relative movement mechanism for relatively moving the table and the spindle,
A touch sensor installed on the upper surface of the workpiece, capable of being contacted at the tip of the tool and capable of detecting tip contact of the tool;
A position detection device for detecting a coordinate position of the touch sensor;
A control device,
The controller moves the table and the spindle relative to each other by driving the relative movement mechanism so that the tool is positioned at the coordinate position detected by the position detector, and then moves the tip of the tool to the tip. Relative movement command means for contacting the touch sensor, and tool length measuring means for measuring the tool length of the tool based on a contact detection signal from the touch sensor.
A machine tool characterized by that.

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