JP2011041985A - Tool rotating-direction positioning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tool rotating-direction positioning method for highly accurately positioning the rotating direction of a tool in a short time with a simple construction. <P>SOLUTION: The tool rotating-direction positioning method is provided for moving the tool 32 mounted on a spindle 15 relative to a work W, and controlling the rotating angle of the spindle 15 to position the tool 15 in the rotating direction prior to cutting work with a working face 32a of the tool 32 consistently in the cutting direction. The method includes imaging of the tool 32 from its lateral side while indexing the spindle 15 at a predetermined indexing angle, using the imaged image for continuously measuring a measurement distance L between the rotational axis of the spindle 15 and the working face 32a, acquiring a curve showing a relationship between a rotating angle θ of the spindle and the measurement distance L, using the curve for finding a rotating angle θo corresponding to a measurement distance Lo as the local extremum of the curve, and controlling the spindle 15 to be at the rotating angle θo. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rotational direction positioning method for a tool that positions a tool mounted on a spindle of a machine tool in a rotational direction so that the tool is oriented in a desired direction.

  In a machine tool such as a milling machine or a machining center, a workpiece is machined into a desired shape by relatively moving a tool mounted on a spindle and a workpiece fixed to a table. Further, in such a machine tool, a rotary tool such as an end mill or a drill is used, and a non-rotary tool such as a hail tool is also used. And this non-rotating type tool is often used for grooving, and the shape of the tool front is generally adapted to the cross-sectional shape of the groove to be machined.

  Therefore, when machining a workpiece with a non-rotating tool mounted on the spindle of the machine tool, the tool always faces the cutting direction in synchronization with the relative movement between the tool and the workpiece. The rotation angle of the main shaft is controlled so that it faces. As a result, since the posture of the tool remains unchanged with respect to the cutting direction during machining, the positional relationship between the tool and the workpiece is set so that the tool faces the front with respect to the cutting direction before machining. Must be set. That is, when machining is performed using a non-rotating type tool, it is necessary to start machining after positioning the tool in the rotational direction.

  However, it is very difficult to manually match the tool front face with the cutting direction by the operator's manual work. If the tool front angle does not match, an error occurs in the machining shape. Therefore, a method has been proposed in which the tool is automatically positioned in the rotational direction after the tool is mounted. Such a method for positioning the rotational direction of the tool is disclosed in Patent Document 1, for example.

JP 2008-87080 A

  In the above conventional positioning method, the measuring element is brought into contact with the flat reference surface and the cylindrical surface of the tool holder, and the reference surface of the tool holder is set in the cutting direction based on the machine coordinate value when the measuring element comes into contact. The rotation angle of the main shaft is controlled so as to face.

  However, in such a positioning method, the tool holder has to be processed into a special shape, and the manufacturing cost of the tool holder is increased. In addition, since the tool holder has a special shape, the number of times of measurement by the probe for estimating the current rotation angle of the tool holder increases, and the time until the tool positioning is completed may increase.

  In addition, since the tool holder is provided with a reference plane in spite of positioning the tool in the rotational direction, the rotational direction alignment (phase alignment) between the tool holder and the tool must be performed with high accuracy. I must. Since tool errors and assembly errors occur in the tool holder and tool, it is difficult to align these positions with high accuracy. As a result, positioning of the tool in the rotational direction is performed with high accuracy. Will be difficult.

  Accordingly, the present invention solves the above-described problems, and provides a tool rotation direction positioning method capable of positioning a tool in the rotation direction with a simple configuration and in a short time with high accuracy. With the goal.

The rotational direction positioning method of the tool according to the first invention for solving the above-mentioned problem is as follows.
Prior to the cutting process in which the tool mounted on the spindle and the workpiece are relatively moved and the rotation angle of the spindle is controlled so that the machining surface of the tool is always oriented in the cutting direction, the rotation direction of the tool In the rotational direction positioning method of the tool for positioning
While indexing the spindle at a predetermined indexing angle, image the tool from its side,
Using the image obtained by the imaging, continuously measuring the distance between the rotation axis of the main shaft and the processing surface,
Obtaining a curve showing the relationship between the rotation angle of the spindle and the measured distance;
Using the curve, find the positioning rotation angle corresponding to the optimum distance that is the extreme value of the curve,
The main shaft is controlled to the positioning rotation angle.

The rotational direction positioning method of the tool according to the second invention for solving the above-mentioned problem is as follows.
After obtaining the positioning rotation angle, index the spindle at an index angle gradually reduced from the predetermined index angle, repeatedly image the tool,
The positioning rotation angle is obtained again.

The rotational direction positioning method of the tool according to the third invention for solving the above-mentioned problem is as follows.
The spindle is indexed and the tool is repeatedly imaged within a predetermined rotation angle range including the positioning rotation angle that is narrower than the rotation angle range in which the main shaft has been rotated at the previous measurement. And

The rotational direction positioning method of the tool according to the fourth invention for solving the above-mentioned problem is as follows.
When the tool is reused, the rotation angle of the spindle is controlled based on the curve, the optimum distance, and the positioning rotation angle.

A rotational direction positioning method for a tool according to a fifth aspect of the present invention for solving the above problem is as follows.
Set an allowable range for the optimum distance recorded at the first use of the tool,
Controlling the rotation angle of the spindle so that the measurement distance between the rotation axis of the spindle and the machining surface in the image obtained by imaging is within the allowable range when the tool is reused. Features.

A rotational direction positioning method for a tool according to a sixth invention for solving the above-described problems is as follows.
Based on the measured distance between the rotation axis of the spindle and the machining surface in the image obtained by imaging when the tool is reused, and the curve recorded at the first use of the tool, It is characterized by controlling the rotation angle.

A rotational direction positioning method for a tool according to a seventh invention for solving the above-described problems is as follows.
Using the curve, find the positioning rotation angle corresponding to the measurement distance,
When the positioning rotation angle corresponding to the optimum distance is different from the positioning rotation angle corresponding to the measurement distance, the spindle is controlled to the positioning rotation angle corresponding to the optimum distance. .

  Therefore, according to the rotation direction positioning method of the tool according to the present invention, the tool is imaged from the side while the spindle is indexed at a predetermined index angle, and the spindle is rotated using the image obtained by the imaging. The distance between the axis and the machined surface is continuously measured, a curve indicating the relationship between the rotation angle of the spindle and the measured distance is obtained, and this curve is used to obtain the optimum extreme value of the curve By determining the positioning rotation angle corresponding to the distance and controlling the spindle to the positioning rotation angle, the tool can be positioned in the rotational direction with high accuracy and in a short time with a simple configuration.

It is a schematic block diagram of the machine tool to which the rotation direction positioning method of the tool which concerns on one Example of this invention is applied. It is a schematic block diagram of an imaging device. It is a perspective view of a tool. It is the figure which showed the change of the measurement distance by the main shaft rotation at the time of imaging. It is the flowchart which showed the rotation direction positioning method of the tool at the time of first time use. It is the figure which showed the relationship between the rotation angle of the main axis | shaft in FIG. 5, and a measurement distance. It is the flowchart which showed the rotation direction positioning method of the tool at the time of reuse. It is the figure which showed the relationship between the rotation angle of the main axis | shaft in FIG. 7, and a measurement distance. It is the other flowchart which showed the rotation direction positioning method of the tool at the time of reuse. It is the figure which showed the relationship between the rotation angle of the main axis | shaft in FIG. 9, and a measurement distance.

  Hereinafter, the rotational direction positioning method of the tool according to the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, a bed 11 is provided at the lower part of the machine tool 1. A column 12 is erected on the upper surface of the bed 11, and a saddle 13 is supported on the front surface of the column 12 so as to be movable in the horizontal X-axis direction. Further, a spindle head 14 is supported on the front surface of the saddle 13 so as to be movable in the vertical Z-axis direction. A spindle 15 is supported on the spindle head 14 so as to be rotatable around the vertical C-axis. .

  A tool 32 is detachably attached to the main shaft 15 via a tool holder 31. Here, as shown in FIG. 3, the tool 32 is a non-rotating tool such as a hail tool, and a rake face (working face) 32 a is formed on the front face thereof.

  An automatic tool changer 16 is provided on the side of the column 12. This automatic tool changer 16 selects a tool for the next machining from a large number of held tools and automatically exchanges the tool for the next machining and the tool 32 mounted on the spindle 15. It is.

  A table 17 is supported on the upper surface of the bed 11 in front of the column 11 so as to be movable in the horizontal Y-axis direction. Further, a workpiece W is detachably attached to the center of the upper surface of the table 15, and a tool imaging device 18 having a tool imaging function is provided at a corner of the upper surface of the table 15.

  As shown in FIG. 2, the tool imaging device 18 includes a base 41 provided on the upper surface of the table 15, a light projecting unit 42 supported on the upper part of the base 41, and a CCD disposed to face the light projecting unit 42. The camera (imaging means) 43 and a display unit 44 connected to the CCD camera 43 are configured. The light projecting unit 42 emits light toward the tip of the tool 32 mounted on the main shaft 15 when the tool 32 is moved to a predetermined measurement position above the base 41. Is configured to continuously image the tip of the tool 32 at regular time intervals and output the acquired image data to the display unit 44. Further, the display unit 44 converts the image data input from the CCD camera 43 into an image and displays the image on the display screen 44a.

  Here, as shown in FIGS. 1 and 2, the machine tool 1 is provided with an NC device 19 that controls the entire machine tool 1 in an integrated manner. The NC device 19 includes a saddle 13, a spindle head, and the like. 14, a spindle 15, an automatic tool changer 16, a table 17, a tool imaging device 18, and the like. Then, the NC device 19 controls the rotational angle of the spindle 15 around the C axis based on the image of the tool 32 by the tool imaging device 18 before machining (after tool mounting), thereby positioning the tool 32 in the rotational direction. After being performed, the tool 32 is moved in the X-axis direction and the Z-axis direction, the workpiece W is moved in the Y-axis direction, and the spindle 15 is rotated around the C-axis based on machining conditions input to an input device (not shown). By controlling the above, it is possible to process a straight groove or a curved groove on the workpiece W.

  Accordingly, when grooving the workpiece W using the machine tool 1, first, the automatic tool changer 16 is used to change the tool to the spindle 15 and then the tool 32 mounted on the spindle 15. Is moved to the measurement position in the tool imaging device 18. The measurement position in the tool imaging device 18 is a position where the rotation axis (C axis) of the main shaft 15 coincides with the image vertical center line of the CCD camera 43 (display screen 44a).

  Next, when light is emitted from the light projecting unit 42 toward the tip of the tool 32, the tip of the tool 32 is imaged by the CCD camera 43 from the opposite side, and the image data is input to the display unit 44. Thereby, the image of the tip of the tool 32 is displayed on the display screen 44a.

  Then, in the NC device 19, while rotating the spindle 15 forward and backward (see FIG. 4, only forward rotation is shown in FIG. 4), the spindle 15 (tool 32) is used using the image displayed on the display screen 44a. After continuously measuring the distance from the rotation axis of the tool 32 to the rake face 32a of the tool 32 (see FIG. 2), the rotation angle θ of the main shaft 15 when the measured measurement distance L is the shortest is used. Position in the rotational direction. That is, when the measurement distance L is the shortest, the rake face 32a of the tool 31 is in the state of facing the cutting direction. The NC device 19 has a recording function, and is a two-dimensional curve (FIG. 6) showing the measurement distance L when the tool 32 is used for the first time or when it is reused, the corresponding rotation angle θ, and the relationship therebetween. Reference) is recorded.

  Next, to control the movement of the tool 32 in the X-axis direction and the Z-axis direction and the movement of the workpiece W in the Y-axis direction with the tool 32 positioned, to change the cutting direction as necessary. In addition, by controlling the rotation of the main shaft 15 around the C axis, a straight groove or a curved groove is processed in the workpiece W.

  Further, when the tool 32 once detached from the spindle 15 is reused, the rotation angle θ at the first use recorded in the NC device 19, the measurement distance L, and a two-dimensional curve (rotation described later) showing these relationships. The tool 32 is positioned in the rotational direction using the angle θo and the measurement distance Lo).

  Next, a method for positioning the tool 32 in the rotational direction before machining (after tool mounting) will be described in detail with reference to FIGS.

  Initially, the rotational direction positioning method in the case of using the tool 32 for the first time is demonstrated using FIG.5 and FIG.6.

  First, in step S1, the minimum index angle of the spindle 15 is arbitrarily set.

  Next, in step S2, the tool 32 is mounted on the spindle 15 by using the automatic tool changer 16, and the tool 32 is moved to the measurement position in the tool imaging device 18 in step S3.

  In step S4, the rotation angle of the main shaft 15 is controlled so that the rake face 32a of the tool 32 faces a predetermined direction, and the tool 32 is roughly positioned in the rotation direction (rough positioning).

  Next, in step S <b> 5, the tip of the tool 32 is imaged by the CCD camera 43, and the image is displayed on the display screen 44 a of the display unit 44.

  In step S6, the index of the tool 32 is determined from the rotation axis (C axis) of the spindle 15 using the image displayed on the display screen 44a while indexing the spindle 15 in the forward rotation direction and the reverse rotation direction at a predetermined index angle. The measurement distance L to the rake face 32a is continuously measured. Thereby, a downwardly convex two-dimensional curve showing the relationship between the rotation angle θ of the main shaft 15 and the measurement distance L from the rotation axis of the main shaft 15 to the rake face 32a is obtained (see FIG. 6).

  Next, in step S7, the extreme value (minimum value), that is, the measurement distance (optimum distance) Lo when the measurement distance L becomes the shortest is obtained from the two-dimensional curve shown in FIG.

  In step S8, after obtaining a rotation angle (positioning rotation angle) θo corresponding to the measurement distance Lo, a predetermined rotation angle range θa is set so as to straddle the rotation angle θo. Further, within this rotation angle range θa, the measurement distance L is continuously re-measured while the spindle 15 is indexed in the forward direction and the reverse direction at an index angle smaller than the index angle at the previous measurement (step S6). taking measurement. Thereby, in the part including the extreme value in the two-dimensional curve shown in FIG. 6, the relationship between the rotation angle θ and the measurement distance L can be shown more precisely.

  Next, in step S9, the measurement distance Lo when the measurement distance L is the shortest is obtained again from a part of the two-dimensional curve obtained in step S8.

  In step S10, it is determined whether or not the index angle of the spindle 15 at the time of the current measurement (step S8) is the minimum index angle set in step S1.

  Here, if possible, in step S11, after obtaining the rotation angle θo corresponding to the measurement distance Lo obtained in step S9, the spindle 15 is rotated to this rotation angle θo, and the tool 32 is positioned in the rotation direction. Do.

  If NO, the process returns to step S8. Thereafter, the measurement distance Lo is re-determined while gradually reducing the index angle of the spindle 15, and the process continues until the index angle of the spindle 15 reaches the minimum index angle set in step S1. It is done.

  Next, the rotational direction positioning method when the tool 32 is reused will be described with reference to FIGS.

  First, in step S21, as shown in FIG. 8, an allowable error distance | La | for allowing an error on the plus side and the minus side with respect to the latest measured distance Lo recorded at the time of first use of the tool 32. In step S22, the minimum index angle of the spindle 15 is arbitrarily set.

  Next, in step S23, the automatic tool changer 16 is used to attach the tool 32 to the spindle 15, and in step S24, the tool 32 is moved to the measurement position in the tool imaging device 18.

  In step S25, the spindle 15 is rotated to the rotation angle θo corresponding to the measurement distance Lo, and the tool 32 is positioned in the rotation direction.

  Next, in step S <b> 26, the tip of the tool 32 is imaged by the CCD camera 43, and the image is displayed on the display screen 44 a of the display unit 44.

  In step S27, the measurement distance L1 from the rotation axis of the spindle 15 to the rake face 32a of the tool 32 is measured using the image displayed on the display screen 44a (see FIG. 8).

  Next, in step S28, it is determined whether or not the deviation between the measurement distance Lo and the measurement distance L1 is within the error allowable distance | La |.

  If yes, in step S29, the spindle 15 is held at the rotational angle θo in that state, and the tool 32 is positioned in the rotational direction (position I in FIG. 8).

  If not, in step S30, the tool 32 is moved from the rotation axis of the spindle 15 using the image displayed on the display screen 44a while indexing the spindle 15 in the forward rotation direction and the reverse rotation direction at a predetermined index angle. The measurement distance L (L2) to the rake face 32a is continuously measured.

  In step S31, it is determined whether or not the deviation between the measurement distance Lo and the measurement distance L2 at which the measured distance is the shortest is within the error allowable distance | La |.

  If yes, in step S32, the spindle 15 is held at the rotation angle θ2 corresponding to the measurement distance L2, and the tool 32 is positioned in the rotation direction (curve II in FIG. 8).

  If not, in step S33, it is determined whether or not the index angle of the spindle 15 at the current measurement (step S30) is the minimum index angle set in step S22.

  Furthermore, if it is possible, even if the rotation angle of the main shaft 15 is controlled in step S34, the measurement distance L does not fall within the allowable error distance | La | (curve III in FIG. 8). The situation (for example, tool breakage, tool mix-up) is notified to the operator by an alarm display on the display screen 44a.

  If NO, the process returns to step S30. Thereafter, the measurement distance L2 is obtained again while gradually decreasing the index angle of the main spindle 15, and finally the process continues until the index angle of the main spindle 15 reaches the minimum index angle set in step S22. It is done.

  Moreover, the positioning method of the other rotation direction in the case of reusing the tool 32 is demonstrated using FIG.9 and FIG.10.

  First, in step S41, the automatic tool changer 16 is used to mount the tool 32 on the spindle 15, and in step S42, the tool 32 is moved to the measurement position in the tool imaging device 18.

  Next, in step S43, the spindle 15 is rotated to the rotation angle θo corresponding to the measurement distance Lo, and the tool 32 is positioned in the rotation direction.

  In step S44, the tip of the tool 32 is imaged by the CCD camera 43, and the image is displayed on the display screen 44a of the display unit 44.

  Next, in step S45, using the image displayed on the display screen 44a, the measurement distance L3 from the rotation axis of the main shaft 15 to the rake face 32a of the tool 32 is measured, and recorded in the first use of the tool 32 in step S46. Using the latest two-dimensional curve, the rotation angle θ3 corresponding to the measurement distance L3 is obtained (see FIG. 10).

  In step S47, it is determined whether or not the rotation angle θo and the rotation angle θ3 are the same rotation angle.

  If yes, in step S48, the spindle 15 is held at the rotational angle θ3 in that state, and the tool 32 is positioned in the rotational direction.

  If NO, a deviation angle Δθ between the rotation angle θo and the rotation angle θ3 is obtained in step S49.

  Next, in step S50, the main shaft 15 is rotated from the rotation angle θ3 by the deviation angle Δθ, held at the rotation angle θo, and the tool 32 is positioned in the rotation direction.

  In this embodiment, the tool 32 having the rake face 32a formed in front of the tool center line (C axis) is used as the non-rotating tool, but the rake face is cut from the tool center line. You may use the tool formed in the direction back. When such a tool is used, the two-dimensional curve indicating the relationship between the rotation angle of the main shaft and the measurement distance is convex upward, and the measurement distance of the main shaft is an extreme value (maximum value). The rotation angle of the tool is positioned by controlling the rotation angle.

  Therefore, according to the rotation direction positioning method of the tool according to the present invention, the tool 32 is imaged while the main shaft 15 is indexed at a predetermined index angle, and the rotation angle θ of the main shaft 15 and the measurement distance L obtained by the imaging are obtained. By acquiring a two-dimensional curve and controlling the spindle 15 to the rotation angle θo corresponding to the measurement distance Lo that is the extreme value of the two-dimensional curve, the tool 32 can be realized with a simple configuration and in a short time with high accuracy. Can be positioned in the rotational direction.

  Further, after obtaining the rotation angle θo, the main shaft 15 is rotated in the forward rotation direction at an index angle smaller than the index angle at the previous measurement within a predetermined rotation angle range θa set so as to straddle the rotation angle θo. And, by re-measuring the measurement distance L while indexing in the reverse rotation direction, it is possible to increase the accuracy of the rotation angle θo. As a result, the main shaft 15 is indexed in the normal rotation direction and the reverse rotation direction at a small index angle from the beginning, and the measurement distance L is measured gradually from a large index angle at a small index angle rather than continuously. As a result, the entire measurement time can be shortened.

  Further, when the tool 32 is reused, the rotation angle of the spindle 15 is determined based on the rotation angles θ and θo and the measurement distances L and Lo recorded at the first use and the two-dimensional curve showing the relationship between them. By controlling, the time from the completion of tool mounting to the completion of tool positioning can be made shorter than that at the first use.

  The present invention can be applied to a tool length measuring method for measuring a tool length before machining for the purpose of improving machining accuracy.

DESCRIPTION OF SYMBOLS 1 Machine tool 11 Bed 12 Column 13 Saddle 14 Spindle head 15 Spindle 16 Automatic tool changer 17 Table 18 Tool imaging device 19 NC device 31 Tool holder 32 Tool 32a Rake face 41 Base 42 Projection part 43 CCD camera 44 Display part 44a Display screen

Claims (7)

Prior to the cutting process in which the tool mounted on the spindle and the workpiece are relatively moved and the rotation angle of the spindle is controlled so that the machining surface of the tool is always oriented in the cutting direction, the rotation direction of the tool In the rotational direction positioning method of the tool for positioning
While indexing the spindle at a predetermined indexing angle, image the tool from its side,
Using the image obtained by the imaging, continuously measuring the distance between the rotation axis of the main shaft and the processing surface,
Obtaining a curve showing the relationship between the rotation angle of the spindle and the measured distance;
Using the curve, find the positioning rotation angle corresponding to the optimum distance that is the extreme value of the curve,
A method of positioning a tool in a rotation direction, wherein the spindle is controlled to the positioning rotation angle. In the rotation direction positioning method of the tool according to claim 1,
After obtaining the positioning rotation angle, the spindle is indexed at an index angle gradually reduced from the predetermined index angle, and the tool is repeatedly imaged,
A method of positioning the rotation direction of the tool, wherein the positioning rotation angle is obtained again. In the rotation direction positioning method of the tool according to claim 2,
The spindle is indexed and the tool is repeatedly imaged within a predetermined rotation angle range including the positioning rotation angle that is narrower than the rotation angle range in which the main shaft has been rotated at the previous measurement. Rotation direction positioning method of the tool. In the rotation direction positioning method of the tool according to any one of claims 1 to 3,
A rotation direction positioning method for a tool, wherein the rotation angle of the spindle is controlled based on the curve, the optimum distance, and the positioning rotation angle when the tool is reused. In the rotation direction positioning method of the tool according to any one of claims 1 to 3,
Set an allowable range for the optimum distance recorded at the first use of the tool,
Controlling the rotation angle of the spindle so that the measurement distance between the rotation axis of the spindle and the machining surface in the image obtained by imaging is within the allowable range when the tool is reused. A rotational direction positioning method of a tool characterized by the above. In the rotation direction positioning method of the tool according to any one of claims 1 to 3,
Based on the measured distance between the rotation axis of the spindle and the machining surface in the image obtained by imaging when the tool is reused, and the curve recorded at the first use of the tool, A rotation direction positioning method for a tool, characterized by controlling a rotation angle. In the rotation direction positioning method of the tool according to claim 6,
Using the curve, find the positioning rotation angle corresponding to the measurement distance,
When the positioning rotation angle corresponding to the optimum distance is different from the positioning rotation angle corresponding to the measurement distance, the spindle is controlled to the positioning rotation angle corresponding to the optimum distance. Tool rotation direction positioning method.

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