JP4652873B2 - Tool measurement method for machine tools - Google Patents

Description

  The present invention relates to a method for measuring the shape of a cutting tool used for hail machining by a machine tool such as a machining center.

  The machining center is usually used to machine a workpiece using a rotary tool, but instead of a rotary tool, a non-rotating cutting tool such as a hail bite is attached to the main shaft and synchronized with the movement of the X, Y, and Z axes. A machining method generally called hail machining is known in which the front surface of the cutting tool is always oriented in the cutting direction by controlling the angle of the spindle holding the cutting tool at the tip.

  Such hail processing is mainly used for grooving and the like, and the shape of the cutting tool is generally adapted to the shape of the groove to be processed, but in recent years a cutting tool having a cutting edge cross section different from the processing shape There are also examples using. For example, Patent Document 1 proposes a cutting method in which a machining shape having a cross-sectional shape different from the cutting edge cross-section is processed by using a total shape tool in a 5-axis control machining center. In such circumstances, a cutting tool having a circular cutting edge of the tool is highly versatile because it can create an arbitrary free-form surface.

JP-A-6-711

  By the way, when such a non-rotating cutting tool is attached to the main shaft and the processing is performed by controlling the rotation angle of the main shaft, the mounting accuracy of the cutting tool is a very important issue. However, it is very difficult to match the center of rotation of the spindle to which the tool is attached and the center position of the cutting tool, and to match the front angle of the cutting tool, and the misalignment between the center of rotation of the spindle and the center of the cutting tool is difficult. If the front angle of the cutting tool is not consistent, an error has occurred in the machining shape. In addition, the tool radius is not accurately known, which is also a factor causing an error in the machining shape.

  The present invention has been made in view of the above-described problems, and an object of the present invention is, for example, when measuring the shape of a cutting tool used for hail machining by a machine tool such as a machining center, the positional deviation between the spindle rotation center and the tool center. It is to provide a method for measuring the amount, the amount of deviation of the angle in front of the tool, and the tool radius.

In order to solve the above-mentioned problem, the measuring method of the machine tool of the present invention is attached to the main shaft by the movement by the feed axis control in three directions orthogonal to each other, the X axis, the Y axis and the Z axis, and the rotation angle control of the main shaft. In a machine tool for machining a workpiece with a cutting tool, a method for measuring a non-rotating cutting tool having a circular cutting edge used for machining, wherein the tool front surface of the cutting tool is controlled by the rotation angle control of the spindle. And a misalignment in the Y-axis and Z-axis directions (Δy,) between the rotation center of the main shaft and the arc center of the cutting tool when indexing so as to be parallel to a plane including the Y-axis (YZ plane) Δz), angle deviation around the Y axis relative to the YZ plane (β), angle deviation around the Z axis relative to the YZ plane (γ), arc radius of the cutting tool (R) Of which at least one or more n Measurement method for determining an unknown value of the main axis and a positional deviation (Δx) in the X-axis direction between the center of rotation of the spindle and the center of the arc of the cutting tool by a measuring device that measures two-dimensional coordinates in the YZ plane. in, the rotation angle control of the main shaft, said tool front of the cutting tool indexing so as to be substantially parallel to the YZ plane, the cutting edge of any point n Y-axis coordinate and Z-axis coordinate (y _'1, z' ₁ ··· _{y'n, z'n)} measured by the rotation angle control spindle rotated by a predetermined angle, the cutting edge of any point Y axis coordinate and Z-axis coordinate (y ', z') was measured From the arbitrary n points and one measurement edge coordinate, the positional deviation (Δx, Δy, Δz) of the spindle rotation center and the tool center, the angular deviation (β, γ) of the tool front, and the tool radius (R) Among them, an unknown value is obtained.

Here, the positional deviation in the Y-axis and Z-axis directions (from Y-axis coordinates and Z-axis coordinates (y ′ ₁ , z ′ ₁ ... Y ′ _n , z ′ _n ) of the arbitrary n-point cutting edge ( Δy, Δz), an angular deviation about the Y axis (β), an angular deviation about the Z axis (γ), and an arc radius (R) of the cutting tool, and an unknown value obtained. And the position deviation (Δx) in the X-axis direction can be obtained from the Y-axis coordinate and the Z-axis coordinate (y ′, z ′) of the arbitrary one-pointed blade edge after a predetermined angle rotation (claim) Item 2).

Further, the Y-axis coordinate and the Z-axis coordinate (y ′ ₁ , z ′ ₁ ... Y ′ _n , z ′ _n ) of the arbitrary _n- point cutting edge and the arbitrary one-point cutting edge after a predetermined angle rotation The measurement of the Y-axis coordinate and the Z-axis coordinate (y ′, z ′) is preferably performed using a laser beam parallel to the X axis.

  According to the measuring method of the first or second aspect of the present invention, it is possible to accurately obtain the positional deviation amount of the tool center, the angular deviation amount of the tool front, and the tool radius. In addition, the obtained tool center position deviation amount, tool front angle deviation amount, and tool radius are input to the NC device, and the NC device outputs a position command that takes these deviation amounts into account. Shape error can be improved. Further, the amount of deviation of the tool center in the X-axis direction, which cannot be measured by a measuring apparatus that measures coordinates in the plane (YZ plane), can be accurately obtained.

  According to the measuring method of claim 3 of the present invention, the present invention can be easily implemented by using a non-contact type tool length measuring device for an existing machine tool.

  FIG. 4 is a diagram showing a configuration for carrying out the measuring method of the present invention, and is a diagram showing a state in which a cutting tool 1 attached to a spindle of a machining center (not shown) is measured using a non-contact tool length measuring device 2. is there.

  The non-contact tool length measuring device 2 is connected to a machining center (not shown) so that the cutting tool 1 and the non-contact tool length measuring device 2 can move in three orthogonal directions by using a feed axis of the machining center (not shown). It is fixed. This non-contact tool length measuring device 2 is composed of a laser light source 3 and a laser light receiving unit 4 arranged so as to face each other, and the laser light receiving unit 4 receives the laser light 5 emitted from the laser light source 3. When the cutting tool 1 enters the position between the laser light source 3 and the laser light receiving unit 4, the laser beam 5 is cut off, and the laser beam 5 of the cutting tool 1 is cut off from the coordinate value of the feed axis of the machine tool at that time. The coordinates of the position can be calculated. As such a non-contact tool length measuring device 2, a commercially available device such as a laser “MICRO” for machining centers manufactured by BLUM can be used.

  Here, the non-contact tool length measuring device 2 is attached so that the laser beam 5 is parallel to the X axis of the machining center. For this reason, the cutting tool 1 and the non-contact tool length measuring device 2 are moved in the YZ plane so that the cutting tool 1 enters the non-contact tool length measuring device 2, and the cutting tool 1 when the laser beam 5 is interrupted. The coordinates in the Y-axis and Z-axis directions can be measured, and the coordinates in the X-axis direction parallel to the laser beam 5 cannot be measured.

  A tool measuring method of the present invention using this non-contact tool length measuring device 2 will be described. In FIG. 5, the cutting tool 1 is a cutting tool whose cutting edge has an arc shape, and the measurement is performed by the non-contact tool length measuring device 2 in which the laser beam is arranged parallel to the X axis as described above. In order to carry out, the state which controlled the spindle which is not illustrated so that tool front 8 may become parallel to a YZ plane is shown.

  However, in actuality, due to factors such as machining accuracy and assembly accuracy of parts in each part of the machining center, the main shaft rotation center 6 and the tool center 7 have positional deviations Δx, Δy, Δz in the three XYZ directions, respectively, The tool front surface 8 has an angular deviation with respect to the YZ plane.

  Here, in order to make it easier to understand the angular deviation of the tool front surface 8 with respect to the YZ plane, the cutting tool is assumed to be a circle and shown in FIG. FIG. 6A shows an ideal state with no positional deviation or angular deviation, and is a circle of radius R centered at the origin in the YZ plane. In practice, however, the accuracy of the parts and the accuracy of assembly will cause a deviation from this position. If this is decomposed in each direction, it can be considered that the inclination is β around the Y axis as shown in FIG. 6B, and further γ is inclined around the Z axis as shown in FIG. 6C.

  Therefore, in actuality, it can be considered as an arc that translates Δx, Δy, Δz in the XYZ axis directions as a position shift, and that has a β tilt around the Y axis and a γ tilt around the Z axis. The upper position vector p can be expressed as:

  Here, in the present embodiment, since the laser beam 5 is arranged in parallel with the X axis, only YZ coordinates are obtained by measurement, and therefore p can be considered as a mapping (q) to the YZ plane. And can be expressed as:

Therefore, when the nth measurement coordinate by the laser beam 5 is (y, z) = (y ′ _n , c ′ _n ), it can be expressed as follows.

  In order to obtain the unknown parameters β, γ, Δy, Δz, R from this equation, a total of 15 is obtained by measuring any five points on the tool outer shape and putting each Y coordinate and Z coordinate in the above equation. Can be obtained by making the following equation and solving this equation.

  Further, in order to obtain Δx, a known angle θ is rotated around the Z axis, and the mapping γ onto the YZ plane can be similarly expressed as follows.

Therefore, after completing the measurement at five locations, the main axis is rotated by a known angle θ, and an arbitrary sixth point is measured to obtain the following equation, and Δx can be obtained.

  Since these equations are non-linear equations, they cannot be solved directly, but can be obtained by iteratively solving using the Newton-Raphson method.

  An example of the tool measuring method according to the present invention will be described with reference to FIGS. FIG. 1 is a flowchart of the measurement method of the present invention, and FIGS. 2 and 3 show the state of the cutting tool and laser light during the measurement of the present invention. FIG. 2 (a) shows a state in which the cutting tool 1 with the tool front surface 8 directed in the X-axis direction is viewed from the tool front direction by controlling the spindle, and FIG. 2 (b) is a view from the Z-axis direction tool front end side. Shows the state. FIG. 3A shows a state in which the cutting tool 1 after the tool front surface 8 is turned by a predetermined angle θ by controlling the spindle is viewed from the X-axis direction tool front side, and FIG. 3B shows the Z-axis direction. The state seen from the tool front end side is shown.

  This will be described based on the flowchart of FIG. In advance, the cutting tool 1 rotates the spindle so that the tool front surface 8 faces the X axis direction, and moves the laser by moving in the YZ direction between the laser light source 3 and the laser light receiving unit 4 as shown in FIG. It is positioned at a position where it can be shut off.

First, in S1, by moving the cutting tool 1 relative to the non-contact tool length measuring device 2 in the YZ plane with the spindle angle fixed, five YZ coordinates of the tool edge shown in FIG. (Y ′ ₅ , z ′ ₅ ) is measured from (y ′ ₁ , y ′ ₁ ). Next, in S2, as shown in FIG. 3B, the main shaft is rotated by a known angle θ. Subsequently, in S3, the YZ coordinate (y ′ ₆ , z) of the sixth tool edge shown in FIG. 3A is obtained by moving the cutting tool 1 relative to the non-contact tool length measuring device 2 in the YZ plane. ' ₆ ) is measured. Finally, in S4, the above-described equations are calculated from the measured values to determine the positional deviation amounts Δx, Δy, Δz, the angular deviation amounts β, γ of the tool front, and the tool radius R.

  The tool center position deviation amounts Δx, Δy, Δz, the tool front angle deviation amounts β, γ, and the tool radius R, which can be obtained as described above, are input to the NC apparatus, and the positions taking these deviation amounts into account. An error of the machining shape can be improved by outputting the command from the NC device.

  In the above embodiment, the tool center position deviation amounts Δx, Δy, Δz, the tool front angle deviation amounts β, γ, and the tool radius R are all obtained. If there is a known value, the number of coordinates to be measured may be reduced.

  In addition, when the present invention is used for calculating only the positional deviation amount in the three orthogonal axes, or when calculating only the angular deviation amount in front of the tool, a known value other than the previously obtained value is entered in the above formula. It is also possible to use a simplified expression.

  In the above embodiment, the non-contact tool length measuring device is arranged so that the laser beam is parallel to the X axis, and as a result, the positional deviation amount Δx in the X axis direction is finally obtained. However, the present invention is not limited to this, and the laser beam may be arranged so as to be parallel to another feed axis, for example, the Y axis. By rotating and measuring one point, the amount of positional deviation in the Y-axis direction is obtained.

  Furthermore, the tool length measuring device is not limited to the non-contact type, and any device that can determine the coordinate values in the two directions within a plane including the two directions of the feed shaft may be used.

It is a flowchart which shows an example of the tool measuring method by this invention. It is a figure which shows the measuring point of a tool blade edge when the tool front by the tool measuring method of this invention faces the X-axis direction. It is a figure which shows the measuring point of the tool blade edge in the state which the tool front surface by the tool measuring method of this invention rotated predetermined angle with respect to the YZ plane. It is a figure which shows the structure which implements the measuring method of this invention. It is a figure which shows the positional relationship of the tool at the time of the tool measurement of this invention, and a spindle rotation center. It is a figure explaining the positional relationship of a tool and a spindle rotation center.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cutting tool 2 ... Non-contact tool length measuring device 3 ... Laser light source 4 ... Laser light-receiving part 5 ... Laser beam 6 ... Spindle center of rotation 7 ... Tool center 8. ..Tool front

Claims (3)

In a machine tool that processes a workpiece with a cutting tool attached to the main axis by movement by three-direction feed axis control of X, Y, and Z axes orthogonal to each other and rotation angle control of the main axis, the cutting edge used for processing is an arc A method of measuring a non-rotating cutting tool having a shape, wherein the tool front surface of the cutting tool is divided so as to be parallel to a plane (YZ plane) including the Z axis and the Y axis by controlling the rotation angle of the spindle. Position deviation (Δy, Δz) between the rotation center of the main shaft and the arc center of the cutting tool in the Y-axis and Z-axis directions, and angle deviation of the tool front surface around the Y-axis with respect to the YZ plane (Β), at least one or more unknown values among the angle deviation (γ) around the Z axis with respect to the YZ plane on the front surface of the tool, and the arc radius (R) of the cutting tool, The center of rotation and the arc of the cutting tool In the method of the said X-axis direction position deviation ([Delta] x), determined by a measuring device for measuring the two-dimensional coordinates in the YZ plane with,
By controlling the rotation angle of the spindle, the tool front of the cutting tool is indexed so as to be substantially parallel to the YZ plane,
Measure Y-axis coordinates and Z-axis coordinates (y ′ ₁ , z ′ ₁ ... Y ′ _n , z ′ _n ) of an arbitrary n-point cutting edge,
Rotate the spindle by a predetermined angle by rotation angle control,
Measure the Y-axis coordinate and Z-axis coordinate (y ′, z ′) of any one cutting edge,
From the arbitrary n points and one measurement edge coordinate, the position deviation (Δx, Δy, Δz) between the spindle rotation center and the tool center, the angle deviation (β, γ) of the tool front, and the tool radius (R) A method for measuring a tool of a machine tool characterized by obtaining an unknown value. From the Y-axis coordinate and the Z-axis coordinate (y ′ ₁ , z ′ ₁ ... Y ′ _n , z ′ _n ) of the arbitrary n-point cutting edge, the positional deviation (Δy, Δz) in the Y-axis and Z-axis directions. ), Determining an unknown value among the angular deviation (β) about the Y axis, the angular deviation (γ) about the Z axis, and the arc radius (R) of the cutting tool,
The positional deviation (Δx) in the X-axis direction is obtained from the obtained unknown value and the Y-axis coordinate and the Z-axis coordinate (y ′, z ′) of the arbitrary one point of the blade after being rotated by a predetermined angle. A tool measuring method for a machine tool according to claim 1. Y-axis coordinate and Z-axis coordinate (y ′ ₁ , z ′ ₁ ... Y ′ _n , z ′ _n ) of the arbitrary _n- point cutting edge, and the Y-axis of the arbitrary one-point cutting edge after a predetermined angle rotation The tool measurement method for a machine tool according to claim 1 or 2, wherein measurement of coordinates and Z-axis coordinates (y ', z') is performed using a laser beam parallel to the X-axis.

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