JP6847650B2 - Machine tool and tool tip position correction method - Google Patents

Description

The present invention relates to a machine tool that performs machining by moving a tool relative to a work mounted on a mounting table. Alternatively, the present invention relates to a method of correcting a tool tip position in such a machine tool.

Conventionally, for example, a ball end mill has been used to form a curved surface on the surface of a work. In this machining, a tool that has reached the end of its life may be replaced with the same tool with the same diameter, or the tool may be replaced with another tool with a different cutting edge diameter depending on the radius of curvature of the target curved surface and the machining position. is there. In this case, it is desirable that the curved surface formed by the tool before replacement and the curved surface formed by the tool after replacement are smoothly continuous. For this purpose, it is necessary to accurately match the position of the tool tip before replacement and the position of the tool tip after replacement in consideration of the posture change (posture error) of the machine tool at that time.

Regarding the position of the tool tip, for example, as described in Japanese Patent Application Laid-Open No. 10-138097 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2012-18093 (Patent Document 2), the extending direction (posture) of the tool and the position of the tool tip It is generally evaluated based on the length of the tool. Specifically, the machine tool is provided with a light-shielding detection device capable of providing a light path for the laser beam and detecting the light-shielding state of the laser light, and the tip of the tool is moved from a predetermined position to the light path for the laser light. The laser beam is blocked by the tip. The shading detection device outputs a skip signal to the control device of the machine tool when the shading starts. When the control device receives the skip signal, the movement of the tool is stopped, and the length of the tool is evaluated based on the amount of movement from the predetermined position.

Then, for example, when the tool is replaced, the position of the tool tip before the replacement is based on the difference between the length of the tool before the replacement and the length of the tool after the replacement before the machining of the work is restarted. The tool after replacement is positioned so that the position of the tip of the tool after replacement coincides with the position of the tip of the tool after replacement. This measurement is based on the assumption that the machine tool has no spatial attitude error, and the length of the tool only indicates the amount of shift of the reference point of the machine tool. You do not have to measure it. For example, the length of the tool may be measured in advance using a tool presetter or the like.

However, even when the length of the tool is accurately evaluated and the tool is positioned, there is a slight deviation between the position of the tool tip before replacement and the position of the tool tip after replacement. As a result, the curved surface formed by the tip of the tool before replacement and the curved surface formed by the tip of the tool after replacement may not be smoothly continuous (a step is generated). Such a deviation is mainly caused by a change in the attitude of the machine tool due to an error caused by thermal deformation caused by a temperature change in the working environment in a series of components from the mounting table on which the work is placed to the spindle. (Attitude error) becomes apparent as a step on the machined surface with the replacement of the tool, and is particularly remarkable in the coordinate system including rotation in the three orthogonal axes rather than in the coordinate system with only the three orthogonal axes.

Japanese Unexamined Patent Publication No. 10-138097 Japanese Unexamined Patent Publication No. 2012-18093

By directly evaluating the position of the tip of the tool, the inventor of the present invention changes the posture of the machine tool due to an error generated in a series of components from the mounting table on which the work is placed to the tool (posture error). ), It was found that the position of the tool tip after the posture change or replacement can be positioned with good reproducibility.

The present invention has been devised based on the above findings. An object of the present invention is that the position of the tool tip is directly evaluated in a state including the posture error of the machine tool as described above, so that the position including the posture error is before the posture change or before replacement. It is possible to accurately match the position of the tool tip of the tool with the position of the tool tip after the posture change or replacement, and it is possible to smoothly continue the formed curved surface without being aware of the posture error. It is to provide a method of correcting the position of a machine tool and a tool tip.

The present invention includes a mounting table on which a work is placed and a mounting table.
A tool having a tool tip while processing the work placed on the above-mentioned stand, and a tool
A light-shielding detection device fixed to the above-mentioned stand, which provides an optical path for the laser light and detects the light-shielding state of the laser light.
A tool control device, which is connected to the above-mentioned stand via a support structure and controls the posture and position of the tool, is provided.
The tool control device is provided with a reference point associated with the tool.
Based on the first tool posture which is the tool posture at the time of machining the tool and the tool length of the tool, the tool control device positions the tip of the tool at the measurement position of the laser beam while maintaining the first tool posture. It is a machine tool characterized in that the position of the first tool, which is the position of the reference point when actually matching the above, is specified.

According to the present invention, the position of the tool tip of the tool before or before the posture change can be accurately specified in a state including the posture error of the machine tool. The tool tip of the tool can be matched exactly. This makes it possible to provide a machine tool capable of smoothly continuing the formed curved surface without being aware of the posture error.

The first tool position is such that when the tool is moved in the uniaxial direction while maintaining the first tool posture by the tool control device, the measurement position of the laser beam is shielded by the first portion of the tool. It may be obtained based on two positions, that is, the position of the reference point when the tool is moved in the uniaxial direction and the position of the reference point when the second portion of the tool is shielded from light when the tool is moved in the uniaxial direction. ..

The tool control device of the tool so that the reference point exists on a straight line connecting the measurement position of the laser beam and the midpoint of the two positions while maintaining the tool in the first tool posture. The position is controlled, and the tool is moved so that the reference point follows the straight line while maintaining the tool in the first tool posture.
The first tool position may be determined based on the position of the reference point when the measurement position is shielded from light by the tool tip when the tool is moved along the straight line.

In these cases, the position of the tool tip can be accurately specified in a state including the posture error occurring in the machine tool.

In the present invention, the tool control device is
When the tool posture during machining is changed from the first tool posture to the second tool posture, based on the second tool posture and the tool length, the tool tip is subjected to the laser while maintaining the second tool posture. The position of the second tool, which is the position of the reference point when the light actually matches the measurement position of the light, is specified.
Based on the difference between the first tool position and the second tool position, the position of the tool tip portion in the second tool posture of the tool may be corrected.

In this case, since the position of the tool tip of the tool before the posture change and the position of the tool tip of the tool after the posture change can be accurately specified with the posture error included, both positions can be specified. Is easy to match exactly.

Alternatively, in the present invention, the tool control device is
When the tool is replaced with another tool, the laser beam is applied to the tool tip of the other tool while maintaining the first tool posture based on the first tool posture and the tool length of the other tool. The position of the third tool, which is the position of the reference point when actually matching the measurement position of the above, is specified.
Based on the difference between the first tool position and the third tool position, the position of the tool tip portion in the first tool posture of the other tool may be corrected.

In this case, since the position of the tool tip of the tool before replacement and the position of the tool tip of the tool after replacement can be accurately specified with the posture error included, both positions can be accurately specified. It is easy to match with.

The tool control device may be capable of 5-axis control of the tool. In this case, the posture of the tool and the position of the tip of the tool can be freely controlled.

An example of a tool used in such a machine tool is a ball end mill.

The method of correcting the position of the tool tip in the machine tool as described above is also subject to the protection of the present application. That is, the present invention is a method for correcting the position of the tool tip of a machine tool.
The machine tool processes a mounting table on which a work is placed and the work mounted on the mounting table described above, and is fixed to a tool having a tool tip and a mounting table described above to provide an optical path for laser light. It also has a light-shielding detection device that detects the light-shielding state of the laser beam, and a tool control device that is connected to the above-mentioned stand via a support structure to control the posture and position of the tool.
The tool control device is provided with a reference point associated with the tool.
Based on the first tool posture, which is the tool posture at the time of machining the tool, and the tool length of the tool, the tool control device emits the laser beam at the tool tip portion of the tool while maintaining the first tool posture. The matching process that actually matches the measurement position of
It is characterized by including a first tool position specifying step for specifying a first tool position which is a position of the reference point when the tool tip portion is actually matched with the measurement position of the laser beam. It is a correction method to be performed.

According to the present invention, the position of the tool tip of the tool before or before the posture change can be accurately specified in a state including the posture error of the machine tool. The tool tip of the tool can be matched exactly. This makes it possible to provide a method for correcting the position of the tool tip portion, which can smoothly continue the formed curved surface without being aware of the posture error.

The matching step is
A first moving step in which the tool control device moves the tool in the uniaxial direction while maintaining the first tool posture.
In the first moving step, when the tool control device moves the tool in the uniaxial direction and the position of the reference point when the measurement position of the laser beam is shielded by the first portion of the tool. It may include a specific step of specifying the position of the reference point when the second portion of the tool is shielded from light and the two positions of the reference point.

Further, the specific step is performed.
The position of the tool is controlled so that the reference point exists on a straight line connecting the measurement position of the laser beam and the midpoint of the two positions while maintaining the tool in the first tool posture. A step of moving the tool so that the reference point follows the straight line while maintaining the tool in the first tool posture.
It may include a step of specifying the position of the reference point when the measurement position is shielded from light by the tool tip when the tool is moved along the straight line.

In these cases, since the position of the tool tip can be accurately specified including the posture error occurring in the machine tool, the position of the tool tip can be accurately corrected.

In the above correction method, when the tool posture during machining is changed from the first tool posture to the second tool posture, the second tool posture is maintained based on the second tool posture and the tool length. A second tool position specifying step of specifying the second tool position, which is the position of the reference point when the tool tip portion of the tool is actually matched with the measurement position of the laser beam.
A second tool position correction step of correcting the position of the tool tip portion in the second tool posture of the tool based on the difference between the first tool position and the second tool position may be further provided. ..

In this case, since the position of the tool tip of the tool before the posture change and the position of the tool tip of the tool after the posture change can be accurately specified with the posture error included, both positions can be specified. Is easy to match exactly.

Alternatively, in the above correction method, when the tool is replaced with another tool, the other tool is maintained while maintaining the first tool posture based on the first tool posture and the tool length of the other tool. The third tool position specifying step of specifying the third tool position, which is the position of the reference point when the tip of the tool is actually matched with the measuring position of the laser beam,
Further provided with a third tool position correction step of correcting the position of the tool tip portion in the first tool posture of the other tool based on the difference between the first tool position and the third tool position. It's okay.

In this case, since the position of the tool tip of the tool before replacement and the position of the tool tip of the tool after replacement can be accurately specified with the posture error included, both positions can be accurately specified. It is easy to match with.

According to the present invention, the position of the tool tip of the tool before or before the posture change can be accurately specified in a state including the posture error of the machine tool. The tool tip of the tool can be matched exactly. This makes it possible to provide a machine tool capable of smoothly continuing the formed curved surface without being aware of the posture error.

Alternatively, according to the present invention, the position of the tool tip of the tool before or before the attitude change can be accurately specified in a state including the attitude error of the machine tool, so that the position after the attitude change or after the attitude change or The tip of the tool after replacement can be accurately matched. This makes it possible to provide a method for correcting the position of the tool tip portion, which can smoothly continue the formed curved surface without being aware of the posture error.

It is a schematic perspective view of the machine tool of one Embodiment of this invention. It is a figure which shows typically the series of component parts of the machine tool of FIG. It is a schematic front view of the index head to which a tool is attached of the machine tool of FIG. It is a schematic perspective view of the shading detection device adopted in the machine tool of FIG. It is a block diagram which shows the connection relationship of the control device of the machine tool of FIG. 1, the shading detection device, and the drive part. It is the schematic perspective view for demonstrating the process of specifying the reference point of the machine tool of FIG. 1 using a reference tool. It is a schematic side view for demonstrating the process of specifying the reference point of the machine tool of FIG. 1 using a reference tool. It is a schematic front view for demonstrating the process of specifying the reference point of the machine tool of FIG. 1 using a reference tool. It is a figure for demonstrating the process of finding the actual position of the tool tip portion while maintaining the tool posture at the time of machining, and is the schematic perspective view which shows the tool just before the start of the process. It is a figure for demonstrating the process of finding the actual position of the tool tip portion while maintaining the tool posture at the time of machining, and is the schematic perspective view which shows the process of rotating a shading detection device with respect to a tool. It is a schematic side view of FIG. 9A. It is a figure for demonstrating the process of finding the actual position of the tool tip part while maintaining the tool posture at the time of machining, and is the light-shielding detection device of the tool tip part based on the tool posture at the time of machining and the tool length stored in advance. It is a schematic perspective view which shows the process of matching with the measurement position of. It is a schematic side view of FIG. 10A. It is a figure for demonstrating the process of finding the actual position of the tip part of a tool while maintaining the tool posture at the time of machining, and is the schematic perspective view which shows the process of positioning for measuring the cylindrical part of the same diameter of a tool. is there. It is a schematic side view of FIG. 11A. It is a figure for demonstrating the process of finding the actual position of the tool tip part while maintaining the tool posture at the time of machining, and is moving the tool in a uniaxial direction toward a laser beam, and measuring one side of a cylindrical part of the same diameter. It is a schematic perspective view which shows the process. It is a schematic side view of FIG. 12A. It is a figure for demonstrating the process of finding the actual position of the tip part of a tool while maintaining the tool posture at the time of machining, and is the outline which shows the process of positioning to measure the opposite side of the cylindrical part of the same diameter of a tool. It is a perspective view. It is a schematic side view of FIG. 13A. It is a figure for demonstrating the process of finding the actual position of the tool tip portion while maintaining the tool posture at the time of machining, and is the schematic perspective view which shows the process of measuring the opposite side of the cylindrical part of the same diameter. It is a schematic side view of FIG. 14A. It is a figure for demonstrating the process of determining the actual position of the tool tip portion while maintaining the tool posture at the time of machining, and is the figure for demonstrating the process of specifying the axis line of a tool. It is a figure for demonstrating the process of finding the actual position of the tool tip part while maintaining the tool posture at the time of machining, and is the process of moving the tool so that the measurement position of a shading detection device is positioned on the axis of the tool. It is a schematic perspective view which shows. It is a schematic side view of FIG. 16A. It is a figure for demonstrating the process of finding the actual position of the tool tip part while maintaining the tool posture at the time of machining, and shows the process of moving the tool linearly toward the measurement position along the axis of the tool. It is a schematic perspective view. It is a schematic side view of FIG. 17A.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic perspective view of a machine tool 100 according to an embodiment of the present invention, and FIG. 2 is a diagram schematically showing a series of components of the machine tool 100 of FIG. As shown in FIG. 1, the machine tool 100 of the present embodiment is a portal processing machine. As shown in FIGS. 1 and 2, this portal processing machine is provided on a table 11 on which a work W is placed, a bed 12 that supports the table 11, a foundation 13 that supports the bed 12, and a foundation 13. A pair of columns 14 that are fixed and extend vertically upward in parallel with each other at a position where the bed 12 is sandwiched, and a pair of columns 14 that are supported by the pair of columns 14 and are provided at the posture of the tool grip portion and the tip portion of the tool grip portion, which will be described later. It includes a drive unit 60 (see FIG. 2) as a tool control device that controls the position of the reference point.

The drive unit 60 of the present embodiment is controlled by a control device 50 (see FIG. 5) described later, and has a cross rail 15 movably bridged between a pair of columns 14 and a cross rail 15. A saddle 16 that is movably supported by the cross rail 15 in the horizontal direction (Y-axis direction in FIG. 1) and has a through hole extending in the vertical direction, and a saddle 16 that is supported in the through hole of the saddle 16 and passes through the through hole. It has a ram 17 that can slide in the vertical direction, and an index head 20 that has a tool gripping portion 21 that is engaged with the lower end region of the ram 17 and grips the tool 30 described later in a swivel manner. The drive unit 60 of the present embodiment is provided with a known drive mechanism such as a motor, and the cross rail 15, the ram 17, and the index head 20 are driven by the drive mechanism.

As shown in FIG. 2, the index head 20 of the present embodiment is supported by the ram 17 so as to face the table 11, and is based on a preset device coordinate system (see FIG. 1) and a machining program. Therefore, the posture (orientation) of the tool 30 or the tool gripping portion 21 is controlled. This control is performed based on the coordinate values in the device coordinate system of the reference point 22 (see FIG. 3) set in advance at the tip of the tool grip portion 21. The reference point 22 of the present embodiment exists on the axis of the tool 30 mounted on the tool grip portion 21.

FIG. 3 is a schematic front view of the index head 20 of the machine tool 100 of FIG. 1, showing a state in which the tool 30 is attached to the tool grip portion 21. As shown in FIG. 3, the index head 20 of the present embodiment can perform 5-axis control (control related to the X-axis, Y-axis, Z-axis, B-axis, and C-axis in FIG. 3). Regarding the turning control in the vertical plane (control related to the B axis in FIG. 3), the tool grip portion 21 is placed in an angle range of 0 ° to 95 ° clockwise with respect to the virtual axis pointing vertically downward with the turning center point 23 as the center. In this turning, it is possible to determine the angle every 1 °.

Further, as shown in FIG. 3, the tool 30 of the present embodiment is a ball end mill, and is a hemisphere in which a gripped portion 31 gripped by the tool gripping portion 21 and a blade for processing the work W are formed. It has a shaped tool tip region and a cylindrical portion 33 having the same diameter provided between the gripped portion 31 and the tool tip region. As shown in FIG. 3, in the hemispherical tool tip region, the tool tip portion 32 exists at a position where the tool tip region intersects the axis A of the cylindrical portion 33 having the same diameter. The tool length of the tool 30 is measured in advance by a tool presetter or the like before being mounted on the machine tool 100, and the measurement result (tool length) is stored in the control unit 51 of the control device 50 described later. ..

Returning to FIG. 2, the machine tool 100 of the present embodiment further has a light-shielding detection device 40 fixed on the rotary table 47. A schematic perspective view of the shading detection device 40 is shown in FIG. As shown in FIG. 4, the light-shielding detection device 40 of the present embodiment has a rectangular parallelepiped base 41 and a pair of facing walls 42, 43 provided on the upper surface of the base 41 at predetermined intervals. It has a concave shape as a whole. One wall (the left wall in FIG. 4) 42 is provided with a light emitting portion 45 that emits a laser beam 44 toward the other wall (the right wall in FIG. 4), and the other wall 43 is provided with a light emitting portion 45. Is provided with a light receiving unit 46 that receives the laser light 44. Then, when the light receiving unit 46 changes from the state in which the light receiving unit 46 receives the laser light 44 to the state in which a certain percentage or more of the laser light 44 is shielded from light, a skip signal is transmitted to the control device 50. There is.

As shown in FIG. 4, the rotary table 47 is rotated in such a manner that the rotation center axis L and the optical path of the laser beam 44 are orthogonal to each other. In other words, the rotation center axis L of the shading detection device 40 is also orthogonal to the optical path of the laser beam 44. The intersection where the rotation center axis of the rotary table 47, that is, the rotation center axis L of the light-shielding detection device 40 intersects with the laser beam 44 is the measurement position P where the measurement by the light-shielding detection device 40 is performed.

FIG. 5 is a block diagram showing a connection relationship between the control device 50, the shading detection device 40, and the drive unit 60 of the machine tool 100 of FIG. As shown in FIG. 5, the control device 50 of the present embodiment outputs a control signal for controlling the posture state of the tool 30 or the tool gripping portion 21 and the position of the reference point 22 based on a machining program stored in advance. A control unit 51 that is generated and transmitted to the drive unit 60 is connected to the control unit 51, and the tool 30 or the tool gripping unit 21 is moved by the drive unit 60 so that the tool 30 blocks a certain percentage of the laser beam 44. It has a calculation unit 52 for acquiring a coordinate value in the device coordinate system of the reference point 22 at the time of the operation.

As shown in FIG. 5, the control unit 51 of the present embodiment is connected to the drive unit 60, and the cross rail 15, the ram 17, and the index head 20 are driven based on the instruction from the control unit 51 to drive the work. The tool 30 is positioned with respect to W. Further, as shown in FIG. 5, the above-mentioned shading detection device 40 is connected to the control unit 51, and the calculation unit 52 is the coordinate value of the reference point 22 when the control unit 51 receives the skip signal. Is acquired from the control unit 51. When the tool 30 is measured, the rotary table 47 is rotated by the control unit 51 to position the light-shielding detection device 40 with respect to the tool 30. Further, in the machine tool 100 of the present embodiment, the coordinate values of the optical path of the laser beam 44 are stored in advance in the control unit 51, and the relative value between the reference point 22 of the tool gripping portion 21 and the optical path of the laser beam 44 is stored. The positional relationship can be recognized by the control device 50.

Further, in the drive unit 60, the coordinate values of the optical path of the laser light 44 and the tool gripping part 21 acquired in advance so that the cylindrical portion 33 having the same diameter blocks the laser light 44 while the tool 30 maintains a predetermined posture state. The tool 30 is moved in the uniaxial direction (for example, the Z-axis direction in FIG. 3) of the device coordinate system based on the relative positional relationship between the reference point 22 and the cylindrical portion 33 having the same diameter. In the present specification, the coordinate value of the optical path of the laser beam 44 means the coordinate value of the measurement position P described above in the device coordinate system. The control unit 51 of the control device 50 acquires and manages the coordinate values of the measurement position P in the device coordinate system.

Further, the calculation unit 52 of the present embodiment is the first in the device coordinate system of the reference point 22 when the laser beam 44 comes into contact with the first position X1 of the cylindrical portion 33 having the same diameter when the tool 30 is moved. The midpoint M of the coordinate value Q1 and the second coordinate value Q2 in the device coordinate system of the reference point 22 when they are in contact with each other at the second position X2 of the cylindrical portion 33 having the same diameter is specified (FIG. 15). In the present embodiment, the first position X1 and the second position X2 are shared portions (elliptical cross sections) between the plane and the cylindrical portion 33 having the same diameter as defined by the direction and the vertical direction of the optical path of the laser beam 44. It corresponds to the lower end and the upper end, respectively.

The control device 50 of the present embodiment passes through the drive unit 60 so that the reference point 22 exists on a straight line connecting the measurement position P of the shading detection device and the midpoint M while maintaining the predetermined posture state. The position of the reference point 22 is controlled, and the reference point 22, that is, the tool 30, is further moved along the straight line while maintaining the predetermined posture state. At the time of this movement, the calculation unit 52 acquires the coordinate value in the device coordinate system of the reference point 22 when the tool tip portion 32 of the tool 30 reaches the laser light 44 and blocks a certain percentage of the laser light 44. It has become.

Next, the operation of the machine tool 100 of the present embodiment will be described.

First, prior to the explanation of the measurement procedure of the tool 30, a step of setting coordinate values in the device coordinate system of the reference point 22 which is a calibration step of the machine tool 100 of the present embodiment with reference to FIGS. 6 to 7B. Will be described. 6 to 7B are diagrams for explaining a process of specifying the reference point 22 of the machine tool 100 of FIG. 1 using the reference tool 30'. FIG. 6 is a schematic perspective view thereof, FIG. 7A is a schematic side view thereof, and FIG. 7B is a schematic front view thereof.

In the illustrated example, the reference tool 30'is gripped by the tool gripping portion 21 in the reference posture in which the angles of the B-axis / C-axis of FIG. 6 are all 0 °. Here, the reference tool 30'means a tool whose tool length (distance from the reference point 22 to the tool tip portion 32') can be accurately specified. The tool length of the reference tool 30'is input to the control unit 51 of the control device 50 in advance and is grasped by the control unit 51.

Then, as shown in FIGS. 7A and 7B, the index head 20 is translated in the uniaxial direction (for example, vertically downward) by the drive unit 60, and the measurement position P of the laser beam 44 is moved by the tool tip portion 32'of the reference tool 30'. Is shaded. In the present embodiment, the control device 50 acquires and manages the coordinate values in the device coordinate system of the reference point 22. Then, the translation of the index head 20 is controlled based on the coordinate values in the device coordinate system of the reference point 22 and the measurement position P of the laser beam 44 stored in the control device 50. When the tool tip portion 32'of the reference tool 30' shades a certain percentage of the laser beam 44, the shading detection device 40 transmits a skip signal to the control unit 51 of the control device 50. The control unit 51 that has received the skip signal causes the calculation unit 52 to acquire the coordinate value of the reference point 22 when the skip signal is received. This coordinate value is transmitted from the calculation unit 52 to the control unit 51, and is used as the reference coordinate value (origin of the device coordinate system) of the reference point 22 when the tool tip portion 32'is located at the measurement position P. It is stored in 51.

Next, with reference to FIGS. 8A to 16B, a procedure for correcting the position (coordinate value) of the tool tip portion 32 of the tool 30 in a state including the posture error of the machine tool 100 will be described.

8 to 16B are diagrams for explaining a process of obtaining the actual position of the tool tip portion 32 while maintaining the tool posture during machining. Specifically, FIG. 8 is a schematic perspective view showing the tool 30 immediately before the start of the process, and FIG. 9A is a schematic perspective view showing a process of rotating the shading detection device 40 with respect to the tool 30. 9B is a schematic side view of FIG. 9A, and FIG. 10A assumes that the tool tip portion 32 is aligned with the measurement position P of the shading detection device 40 based on the tool posture at the time of machining and the tool length stored in advance. FIG. 10B is a schematic perspective view showing a process of acquiring the position of the reference point 22 at the time, FIG. 10B is a schematic side view of FIG. 10A, and FIG. 11A is for measuring a cylindrical portion 33 having the same diameter of the tool 30. FIG. 11B is a schematic perspective view showing a step of performing positioning, FIG. 11B is a schematic side view of FIG. 11A, and FIG. 12A shows a cylindrical portion 33 having the same diameter by moving the tool 30 toward the laser beam 44 in the uniaxial direction. FIG. 12B is a schematic side view showing a process of measuring one side, FIG. 12B is a schematic side view of FIG. 12A, and FIG. 13A is a positioning for measuring the opposite side of the same-diameter cylindrical portion 33 of the tool 30. FIG. 13B is a schematic side view showing a process, FIG. 13B is a schematic side view of FIG. 13A, FIG. 14A is a schematic perspective view showing a process of measuring the opposite side of the cylindrical portion 33 having the same diameter, and FIG. 14B is a schematic perspective view showing the process. 14A is a schematic perspective view, FIG. 15 is a diagram for explaining a process of specifying the axis A of the tool 30, and FIG. 16A is a measurement position of the shading detection device 40 on the axis A of the tool 30. FIG. 16B is a schematic perspective view showing a process of moving the tool 30 so that P is located, FIG. 16B is a schematic side view of FIG. 16A, and FIG. 17A is a schematic side view of the tool 30 along the axis A of the tool 30. It is a schematic perspective view which shows the process of moving linearly toward a measurement position P, and FIG. 17B is a schematic side view of FIG. 17A.

First, as shown in FIG. 8, the rotation of the finished tool 30 is stopped, and the posture of the tool 30 immediately before the end of machining, that is, the values of the B axis and the C axis (see FIG. 8) is maintained. To. Then, as shown in FIGS. 9A and 9B, the optical path of the laser beam 44 of the shading detection device 40 is positioned so as to be perpendicular to the axial direction of the tool 30. During this time, the tool 30 is maintained in the posture immediately before the end of machining (the values of the B axis and the C axis are maintained). In addition, in order to facilitate understanding of this step, the shading detection device 40 is shown in a cross-sectional view in FIG. 9B. This also applies to FIGS. 10B, 11B, 12B, 13B, 14B, 16B and 17B. Further, in each of the drawings after FIG. 9A, the illustration of the rotary table 47 is also omitted.

Then, the calculation unit 52 calculates the position of the reference point 22 when the tool tip portion 32 is made to match the measurement position P of the shading detection device 40 based on the tool posture and the tool length at the time of machining. Then, the tool 30 is moved so that the coordinate value of the reference point 22 of the tool gripping portion 21 matches the position (coordinate value) of the reference point 22 obtained by the calculation. Then, the rotary table 47 is rotated around the rotation center axis L so that the optical path of the laser beam 44 and the axis A of the tool 30 are orthogonal to each other. As a result, as shown in FIGS. 10A and 10B, the tool tip 32 of the tool 30 substantially coincides with the measurement position P of the laser beam 44 in a state where the axis A of the tool 30 and the optical path of the laser beam 44 are orthogonal to each other. To do. In FIGS. 8 to 16B, as an example of the posture of the tool 30 immediately before the end of machining, a straight line (tool axis A) connecting the reference point 22 and the turning center point 23 is vertically downward from the turning center point 23. A posture in which an angle α (see FIG. 9B) larger than 45 ° clockwise with respect to the extending virtual axis is shown is shown.

Then, as shown in FIGS. 11A and 11B, the tool 30 is moved upward by the drive unit 60 while maintaining the postures (values of the B axis and the C axis). Specifically, in this movement, the tool 30 is moved vertically upward (upward in FIG. 6B) by a distance equal to twice the diameter D (2D) of the cutting edge D of the tool 30, and the laser beam 44 is in the horizontal plane. It is moved in a direction orthogonal to (to the left in FIG. 6B) by a distance equal to twice the diameter D (2D) of the cutting edge D of the tool 30. This movement is for positioning the tool 30 in advance so that when the tool 30 is moved in the step described later, the laser beam 44 is surely shielded from light by the cylindrical portion 33 having the same diameter instead of the tool tip portion 32. belongs to. By this movement, the cylindrical portion 33 having the same diameter of the tool 30 is positioned vertically above the laser beam 44. In FIG. 6B, the positioned tool 30 is shown by a solid line. In another embodiment, for example, after the light-shielding state of the laser beam 44 is eliminated, the laser beam 44 may be moved by the diameter D of the tool tip region (blade edge), and then the movement may be stopped. Further, when the tool 30 is moved upward by the drive unit 60, the tool 30 may be moved by a certain distance (for example, 20 mm) instead of twice the diameter D of the cutting edge of the tool 30.

Then, as shown in FIGS. 12A and 12B, the tool 30 is moved vertically downward (below FIGS. 12A and 12B) by the drive unit 60 while maintaining the posture. When this movement is continued, it is the lower end portion of the shared portion (elliptical cross section) between the plane defined by the optical path of the laser beam 44 and the plane including the rotation center axis L of the rotary table 47 and the cylindrical portion 33 having the same diameter. The first portion X1 reaches the measurement position P of the shading detection device 40, and the cylindrical portion 33 having the same diameter blocks a certain proportion of the laser beam 44. In FIG. 12B, the tool 30 before movement is shown by a broken line, and the tool 30 when the cylindrical portion 33 having the same diameter blocks a certain percentage of the laser beam 44 is shown by a solid line. When a certain percentage of the laser beam 44 is shielded by the cylindrical portion 33 having the same diameter, the shading detection device 40 transmits a skip signal to the control unit 51 of the control device 50. Upon receiving this skip signal, the control unit 51 causes the calculation unit 52 to acquire the coordinate value of the reference point 22 at that time. This coordinate value is transmitted from the calculation unit 52 to the control unit 51, and is stored in the control unit 51 as the first coordinate value Q1.

Then, as shown in FIGS. 13A and 13B, the control unit 51 that has received the skip signal moves the tool 30 at a position where the cylindrical portion 33 having the same diameter completely crosses the laser beam 44 via the drive unit 60. To stop. In the present embodiment, after the light-shielding state of the laser beam 44 by the same-diameter cylindrical portion 33 is completed, that is, after the same-diameter cylindrical portion 33 completely crosses the laser beam 44, the same-diameter cylindrical portion is further formed. The movement of the tool 30 is stopped at the position where the diameter D of 33 is moved downward. In FIG. 13B, the tool 30 when a certain percentage of the laser beam 44 is shielded from light by the cylindrical portion 33 having the same diameter is shown by a broken line, and the tool 30 after moving (when stopped) is shown by a solid line. ..

Then, as shown in FIGS. 14A and 14B, the drive unit 60 moves the tool 30 vertically upward (above FIG. 14A and FIG. 14B) while maintaining the tool 30 in the above posture. When this movement is continued, the second upper end of the common portion (elliptical cross section) between the plane defined by the optical path of the laser beam 44 and the rotation center axis L of the rotary table 47 and the cylindrical portion 33 having the same diameter. The position X2 reaches the measurement position P of the shading detection device 40, and the cylindrical portion 33 having the same diameter again blocks a certain proportion of the laser beam 44. In FIG. 14B, the tool 30 before movement is shown by a broken line, and the tool 30 when the cylindrical portion 33 having the same diameter blocks a certain percentage of the laser beam 44 is shown by a solid line.

When a certain percentage of the laser beam 44 is shielded by the cylindrical portion 33 having the same diameter, the shading detection device 40 transmits a skip signal to the control unit 51 of the control device 50. Upon receiving this skip signal, the control unit 51 causes the calculation unit 52 to acquire the coordinate value of the reference point 22 at that time. This coordinate value is transmitted from the calculation unit 52 to the control unit 51, and is stored in the control unit 51 as the second coordinate value Q2. When the control unit 51 receives the skip signal, the control unit 51 stops the movement of the tool 30 via the drive unit 60.

Then, as shown in FIG. 15, the calculation unit 52 acquires the midpoint M of the first coordinate value Q1 of the first portion X1 and the second coordinate value Q2 of the second portion X2, and then the shading detection device 40. A straight line connecting the measurement position P of the above and the midpoint is obtained. The obtained straight line is stored in the control unit 51. This straight line can be regarded as the axis A of the cylindrical portion 33 of the same diameter of the tool 30 in the posture, as is clear from the step of blocking the laser beam 44 by the cylindrical portion 33 of the same diameter.

Then, as shown in FIGS. 16A and 16B, the reference point 22 is located on the straight line Am connecting the measurement position P and the midpoint M of the shading detection device 40 while the tool 30 maintains the posture. , Moved by the drive unit 60. As shown in the figure, this movement ends at a position where the axis A of the tool 30 and the optical path of the laser beam 44 intersect outside the tool 30. At this time, the straight line Am coincides with the axis A of the tool 30. In FIG. 16B, the tool 30 before movement is shown by a broken line, and the tool 30 after movement is shown by a solid line.

Then, as shown in FIGS. 17A and 17B, the drive unit 60 moves the tool 30 toward the measurement position P of the light-shielding detection device 40 along the axis A so that the tool 30 blocks the laser beam 44. Move it. When a certain percentage of the laser beam 44 is shielded by the tool tip 32, the shading detection device 40 transmits a skip signal to the control unit 51 of the control device 50. Upon receiving this skip signal, the control unit 51 causes the calculation unit 52 to acquire the coordinate value of the reference point 22 at that time. This coordinate value is transmitted from the calculation unit 52 to the control unit 51, and is stored in the control unit 51 as a coordinate value corresponding to the position of the tool tip portion 32 when the tool tip portion 32 is at the measurement position P. As a result, the actual position (coordinate value) of the tool tip 32 before replacement in a state including the posture error of the machine tool 100 while the tool 30 maintains a predetermined posture state (posture state at the time of machining) becomes Be accurately identified.

Then, the tool 30 is removed from the tool grip portion 21, a new tool 30A for performing the next machining is gripped by the tool grip portion 21, and the steps corresponding to the above FIGS. 8 to 17B are performed after this replacement. It is also executed for the tool 30A of. As a result, the actual position (coordinate value) of the tool tip 32A of the tool 30A after replacement is accurately specified in the tool posture during machining, that is, in a state including the posture error of the machine tool 100.

Then, based on the difference between the actual position of the tool tip 32A of the tool 30A after replacement and the actual position of the tool tip 32 of the tool 30 before replacement, the position of the tool tip 32A of the tool 30A after replacement Is corrected. That is, the tool 30A after replacement is moved so that the position of the tool tip 32A of the tool 30A after replacement coincides with the position of the tool tip 32 of the tool 30 before replacement. As with the tool 30 before replacement, the tool length after replacement is also measured in advance by a tool presetter or the like before being mounted on the machine tool 100, and the measurement result (tool length) is obtained. It is stored in the control unit 51 of the control device 50.

Alternatively, this method is also effective in correcting an error that occurs when the posture of the tool 30 is changed. The error that occurs when the posture of the tool 30 is changed means an error that occurs in the tool tip portion 32 due to the change in the weight balance of the machine tool 100 due to the posture change. The specific correction method is the same as the above-described explanation described in the case of replacing the tool. That is, the above steps corresponding to FIGS. 8 to 17B are also executed for the tool 30 after the posture change. As a result, the actual position (coordinate value) of the tool tip 32 of the tool 30 after the posture change is accurately specified in the tool posture during machining, that is, in the state including the posture error of the machine tool 100.

Then, based on the difference between the actual position of the tool tip 32 of the tool 30 after the posture change and the actual position of the tool tip 32 of the tool 30 before the posture change, the tool tip of the tool 30 after the posture change. The position of 32 is corrected. That is, the tool 30 after the posture change is moved so that the position of the tool tip 32 of the tool 30 after the posture change matches the position of the tool tip 32 of the tool 30 before the posture change.

According to the machine tool 100 of the present embodiment as described above, the attitude error of the machine tool due to the error occurring in the series of components from the table 11 on which the work W is placed to the index head 20 is included. In this state, the position (coordinate value) of the tool tip portion 32 of the tool 30 is directly evaluated. That is, the position of the tool tip portion 32 of the tool 30 before the posture change or replacement can be accurately specified in a state including the posture error. Therefore, the tool tips 32 and 32A of the tools 30 and 30A after the posture change or replacement can be accurately aligned with the positions. This makes it possible to provide a machine tool capable of smoothly continuing the formed curved surface without being aware of the posture error.

Alternatively, according to the method of the present embodiment as described above, the position (coordinate value) of the tool tip portion 32 of the tool 30 is directly evaluated in a state including the posture error of the machine tool. That is, the position of the tool tip portion 32 of the tool 30 before the posture change or replacement can be accurately specified. Therefore, the tool tips 32 and 32A of the tools 30 and 30A after the posture change or replacement can be accurately aligned with the positions. This makes it possible to provide a method for correcting the positions of the tool tip portions 32 and 32A, which can smoothly continue the formed curved surface without being aware of the posture error.

Further, since the drive unit 60 of the present embodiment is capable of 5-axis control of the tool 30 (control related to the X-axis, Y-axis, Z-axis, B-axis and C-axis in FIG. 3), the posture of the tool 30 and The position of the tool tip 32 can be freely controlled.

Further, when the tool posture during machining is changed, the control device 50 emits laser light from the tool tip portion 32 while maintaining the changed tool posture based on the tool posture and the tool length of the tool 30 after the change in posture. The position (coordinate value) of the reference point 22 when actually matching the measurement position P of 44 is specified, and the position of the tool tip 32 of the tool 30 before the posture change and the tool tip of the tool 30 after the posture change are specified. Based on the difference from the position of 32, the position of the tool tip 32 of the tool 30 after the posture change is corrected. Therefore, it is easy to accurately match the position of the tool tip portion 32 of the tool 30 after the posture change with the position of the tool tip portion 32 of the tool 30 before the posture change.

Alternatively, when the tool is replaced with a new tool 30A, the control device 50 is based on the tool posture and tool length of the new tool 30A, and the tool tip portion of the new tool 30A is maintained while maintaining the tool posture during machining. The position of the reference point 22 when the 32A is actually matched with the measurement position P of the laser beam 44 is specified, and the position of the tool tip 32 of the tool 30 before replacement and the position of the tool tip 32A of the new tool 30A are specified. Based on the difference from the above, the position of the tool tip 32A of the new tool 30A in the tool posture during machining is corrected. Therefore, it is easy to accurately match the position of the tool tip 32A of the new tool 30A with the position of the tool tip 32 of the tool 30 before replacement.

In the present embodiment, the case where the coordinate value of the tool tip portion 32 is corrected when the tool 30 is replaced has been described, but in addition to this, for example, time has elapsed without replacing the tool. It is also effective to correct the coordinate value of the tool tip portion 32 when dealing with the posture error generated at that time. That is, if time elapses without replacing the tool 30, a posture error may occur in the machine tool 100 due to a change in room temperature or the like. Therefore, in order to cancel this posture error, the coordinate value of the tool tip 32 is used. It is effective to correct. Specifically, when a long time elapses while holding the tool 30 and a posture error occurs in the machine tool 100 due to a change in room temperature or the like, an error occurs in the position of the tool tip portion 32 of the tool 30. Sometimes. Even in such a case, according to the machine tool of the present embodiment, it is possible to accurately specify the position of the tool tip portion 32 of the tool 30. As a result, the curved surface formed by the tool 30 before the posture change and the curved surface formed by the tool 30 after the posture change can be smoothly made continuous.

The straight line (tool axis A) connecting the reference point 22 and the turning center point 23 is at an angle greater than 45 ° and not more than 95 ° clockwise with respect to the virtual axis extending vertically downward from the turning center point 23. In some cases, that is, when the B-axis is greater than 45 ° and at an angle of 95 ° or less, the tool 30 is vertically driven by the drive unit 60, as described above with reference to FIGS. 12A-14B. It is moved downward (downward in FIGS. 12A-14B). On the other hand, when the angle of the B axis is 0 ° or more and 45 ° or less, the tool 30 may be moved in the horizontal direction (horizontal direction in FIGS. 12A to 14B) by the drive unit 60. As a result, it is possible to prevent the angle formed by the moving direction of the tool 30 and the axial direction of the tool from becoming too small, and it is possible to efficiently measure the tool 30 without increasing the moving distance of the tool 30 so much. it can.

When the angle of the B axis is 0 ° or more and 45 ° or less and the tool 30 is moved in the horizontal direction by the drive unit 60, the cylindrical portion 33 of the same diameter of the tool 30 corresponding to FIG. 11A. In the step of performing positioning for measuring, the tool 30 may be moved horizontally by 2D and vertically downward (in the negative Z-axis direction) by 2D. In this case, the left end portion in FIG. 11A of the shared portion (elliptical cross section) between the horizontal plane including the measurement position P of the shading detection device 40 and the cylindrical portion 33 having the same diameter becomes the first portion, and the shared portion (elliptical shape). The right end portion in FIG. 11A of (cross section) is the second portion. Since the subsequent steps are substantially the same as the above-mentioned steps, detailed description thereof will be omitted.

Further, although the above-described embodiment is described as a machine tool capable of controlling five axes, it can also be applied to a machine tool capable of controlling three orthogonal axes. In this case, the operation linked to the movement of the B axis and the C axis is omitted. In that case, the optical path of the laser beam 44 of the shading detection device 40 is provided so as to be orthogonal to the tool gripped by the spindle regardless of whether the direction of the spindle is vertical or horizontal. Just do it.

11 Table 12 Bed 13 Foundation 14 Pair of columns 15 Cross rail 16 Saddle 17 Ram 20 Index head 21 Tool grip 22 Reference point 23 Swivel center point 30, 30A Tool 30'Reference tool 31 Grip 32, 32A Tool tip 33 , 33A Cylindrical part of the same diameter 40 Shading detection device 41 Base 42, 43 Pair of facing walls 44 Laser light 45 Light emitting part 46 Light receiving part 47 Rotating table 50 Control device 51 Control unit 52 Calculation unit 60 Drive unit 100 Machine tool

Claims (8)

A mounting table on which the work is placed and
The work placed on the above-mentioned pedestal is processed, and a tool having a tool tip and a light-shielding state fixed to the above-mentioned pedestal to provide an optical path for laser light and detect a light-shielding state of the laser light. Detection device and
A tool control device, which is connected to the above-mentioned stand via a support structure and controls the posture and position of the tool, is provided.
The tool control device is provided with a reference point associated with the tool.
Based on the first tool posture which is the tool posture at the time of machining the tool and the tool length of the tool, the tool control device positions the tip of the tool at the measurement position of the laser beam while maintaining the first tool posture. The position of the first tool, which is the position of the reference point when actually matching with, is specified.
The first tool position is such that when the tool is moved in the uniaxial direction while maintaining the first tool posture by the tool control device, the measurement position of the laser beam is shielded by the first portion of the tool. It is obtained based on two positions, the position of the reference point when the tool is moved and the position of the reference point when the second part of the tool is shielded from light when the tool is moved in the uniaxial direction.
The tool control device of the tool so that the reference point exists on a straight line connecting the measurement position of the laser beam and the midpoint of the two positions while maintaining the tool in the first tool posture. The position is controlled, and the tool is moved so that the reference point follows the straight line while maintaining the tool in the first tool posture.
The first tool position is obtained based on the position of the reference point when the measurement position is shielded from light by the tool tip when the tool is moved along the straight line. Machine Tools. The tool control device is
When the tool posture during machining is changed from the first tool posture to the second tool posture, based on the second tool posture and the tool length, the tool tip is subjected to the laser while maintaining the second tool posture. The position of the second tool, which is the position of the reference point when the light actually matches the measurement position of the light, is specified.
The first based on a difference between the tool position and the second tool position, the machine tool according to claim 1, characterized in that for correcting the position of the tool tip in the second tool orientation of the tool. The tool control device is
When the tool is replaced with another tool, the laser beam is applied to the tool tip of the other tool while maintaining the first tool posture based on the first tool posture and the tool length of the other tool. The position of the third tool, which is the position of the reference point when actually matching the measurement position of the above, is specified.
Based on a difference between the third tool position and the first tool position, tool according to claim 1, characterized in that for correcting the position of the tool tip in the first tool attitude of the other tool machine. The machine tool according to any one of claims 1 to 3 , wherein the tool control device is capable of 5-axis control of the tool. The machine tool according to any one of claims 1 to 4 , wherein the tool is a ball end mill. It is a method of correcting the position of the tool tip of a machine tool.
The machine tool processes a mounting table on which a work is placed and the work mounted on the mounting table described above, and is fixed to a tool having a tool tip and a mounting table described above to provide an optical path for laser light. The present invention includes a light-shielding detection device that detects a light-shielding state of the laser beam, and a tool control device that is connected to the above-mentioned stand via a support structure to control the posture and position of the tool. The tool control device is provided with a reference point associated with the tool.
Based on the first tool posture, which is the tool posture at the time of machining the tool, and the tool length of the tool, the tool control device emits the laser beam at the tool tip portion of the tool while maintaining the first tool posture. The matching process that actually matches the measurement position of
A first tool position specifying step for specifying a first tool position, which is a position of the reference point when the tool tip portion is actually matched with the measurement position of the laser beam, is provided .
The matching step is
A first moving step in which the tool control device moves the tool in the uniaxial direction while maintaining the first tool posture.
In the first moving step, when the tool control device moves the tool in the uniaxial direction and the position of the reference point when the measurement position of the laser beam is shielded by the first portion of the tool. Including the position of the reference point when the second part of the tool is shielded from light, and the specific step of specifying the two positions.
The specific step is
The position of the tool is controlled so that the reference point exists on a straight line connecting the measurement position of the laser beam and the midpoint of the two positions while maintaining the tool in the first tool posture. A step of moving the tool so that the reference point follows the straight line while maintaining the tool in the first tool posture.
A correction method comprising a step of specifying the position of the reference point when the measurement position is shielded from light by the tool tip when the tool is moved along the straight line. When the tool posture during machining is changed from the first tool posture to the second tool posture, the tool tip portion of the tool is maintained while maintaining the second tool posture based on the second tool posture and the tool length. The second tool position specifying step of specifying the second tool position, which is the position of the reference point when the laser beam is actually matched with the measurement position of the laser beam.
Further provided is a second tool position correction step of correcting the position of the tool tip portion in the second tool posture of the tool based on the difference between the first tool position and the second tool position. 6. The amendment method according to claim 6. When the tool is replaced with another tool, the laser beam is applied to the tool tip of the other tool while maintaining the first tool posture based on the first tool posture and the tool length of the other tool. The third tool position specifying step of specifying the third tool position, which is the position of the reference point when actually matching the measurement position of
Further provided with a third tool position correction step of correcting the position of the tool tip portion in the first tool posture of the other tool based on the difference between the first tool position and the third tool position. The amendment method according to claim 6 , wherein the method is characterized by the above.

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