Machine tool

Abstract

A machine tool (100) is provided with: a manual pulse generator (50) for manually controlling a feed shaft that moves a main shaft (112) and a table (106) relative to one another; an imaging device (30) that can be attached to the main shaft of the machine tool, for capturing an image of the surface of a workpiece (W) fixed to the table; a display device (28) for displaying the image of the surface of the workpiece (W) captured by the imaging device; and a processing unit (12) for extracting a measurement target from image data of the surface of the workpiece captured by the imaging device and obtaining, by calculation, the coordinates of the measurement target. The processing unit obtains the coordinate values of a reference point of the measurement target from the image data of the surface of the workpiece captured by the imaging device attached to the main shaft, which has been positioned relative to the table by the manual pulse generator such that the center (Om) of the measurement target is disposed substantially at the center (Oc) of the image of the surface of the workpiece displayed on the display device.

Description

machine tools

[0001] This invention relates to a machine tool capable of measuring the position of a workpiece on the machine.

[0002] Patent Document 1 describes a machine tool in which an image measuring head device is attached to the spindle, and image measurements such as edge detection and circle measurement are performed from image data captured by the image measuring head device.

[0003] Japanese Patent Publication No. 2022-026913

[0004] When the workpiece requires precise positioning, such as a semiconductor wafer, measurement using a microscope attached to a machine tool is necessary. However, the machine tool described in Patent Document 1 has a problem in that it is extremely difficult to position the image measurement head relative to the workpiece when the workpiece to be processed is changed.

[0005] Furthermore, measuring workpieces with a microscope requires the operator to perform manual measurements each time. Additionally, manual measurement requires aligning the target object (holes, alignment marks, etc.) to the center of the image. However, the accuracy of this alignment varies depending on the operator's skill, leading to variability in measurement results.

[0006] The present invention aims to solve the problems of the prior art and provides a machine tool that can automatically measure the positions of holes formed in a workpiece, the edges of a workpiece, and alignment marks provided on the surface of a workpiece. Alignment marks are marks provided on the surface of a workpiece that come in various shapes, such as crosses and squares.

[0007] To achieve the above objective, the present invention provides a machine tool comprising: a spindle for mounting a tool; a table facing the spindle and for mounting a workpiece; a feed axis for relative movement between the spindle and the table; an imaging device that can be attached to the spindle of the machine tool and for imaging the surface of a workpiece fixed to the table; a display device for displaying the image of the workpiece surface captured by the imaging device; a processing unit for extracting a measurement target from the image data of the workpiece surface captured by the imaging device and calculating the coordinate values ​​of the center of the measurement target; and a data storage unit for storing the coordinate values ​​of the center of the measurement target as measurement information. When the center of the measurement target is positioned relative to the table at a temporary position within the range of the image of the workpiece surface displayed on the display device, the processing unit determines the position of the reference point of the measurement target on the image data of the workpiece surface captured by the imaging device attached to the spindle, moves the feed axis relative to the table so that the measurement point of the measurement target becomes the center position of the image captured by the imaging device, and measures the coordinate values ​​of the feed axis as the coordinate values ​​of the reference point of the measurement target.

[0008] According to the present invention, when processing a new workpiece for which no measurement information related to the object to be measured has been registered, the coordinate values ​​of the reference point of the object to be measured are determined from the image data of the workpiece surface captured by an imaging device attached to a spindle positioned relative to the table by a manual pulse generator, so that the center of the object to be measured is positioned approximately in the center of the image of the workpiece surface displayed on the display device. This makes it possible to measure accurately without being affected by errors in the field of view size of the imaging device or aberrations of the imaging device's lens.

[0009] This is a schematic diagram showing an example of a machine tool according to the present invention. This is a schematic block diagram showing an example of a workpiece measuring device. This is a flowchart of a workpiece measuring method. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram for explaining the alignment of the center of the image and the center of the non-circular alignment mark. This is a schematic diagram for explaining the alignment of the center of the image and the center of the non-circular alignment mark. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram of the screen displayed on the display unit. This is a schematic diagram for explaining the measurement method when a workpiece has multiple non-circular alignment marks. This is a schematic diagram for explaining the measurement method when a workpiece has multiple non-circular alignment marks. This is a schematic diagram illustrating a measurement method when a workpiece has multiple non-circular alignment marks.

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. Referring to Figure 1, an example of a machine tool to which the present invention is applied is shown. In Figure 1, the machine tool 100 according to a preferred embodiment of the present invention constitutes a vertical machining center and comprises a bed 102 as a base fixed to the floor of the factory, a table 106 provided on the upper surface of the front portion of the bed 102 (left side in Figure 1) so as to be movable in the front-rear direction or in the Y-axis direction (left-right direction in Figure 1) and to which a workpiece W is fixed, a column 104 erected and fixed on the upper surface of the bed 102 at the rear end side of the bed 102 (right side in Figure 1), an X-axis slider 108 provided on the front surface of the column 104 so as to be movable in the left-right direction or in the X-axis direction (direction perpendicular to the plane of the paper in Figure 1), and a spindle head 110 mounted on the front surface of the X-axis slider 108 so as to be movable in the up-down direction or in the Z-axis direction and to rotatably support the spindle 112. The machine tool 100 also comprises an operation panel 200 for an operator to operate the machine tool 100. The present invention is particularly advantageous for thin workpieces W, such as semiconductor wafers.

[0011] A tool (not shown) for machining a workpiece W fixed to the table 106 can be attached to the tip of the spindle 112. In Figure 1, instead of a tool, an imaging device 30 for measuring the workpiece W is attached to the tip of the spindle 112. The imaging device 30 can be attached manually by the operator of the machine tool 100, but preferably it is automatically attached to the tip of the spindle 112 by the automatic tool changer 40 (Figure 2) of the machine tool 100.

[0012] Table 106 is mounted on the upper surface of bed 102 so as to be able to reciprocate along a pair of Y-axis guide rails (not shown) that extend horizontally in the Y-axis direction (left-right direction in Figure 1). Bed 102 is provided with a Y-axis feed device that drives table 106 to reciprocate along the Y-axis guide rails, which includes a ball screw (not shown) extending in the Y-axis direction and a Y-axis servo motor My connected to one end of the ball screw. A nut (not shown) that engages with the ball screw is attached to table 106. Table 106 is also mounted with a Y-axis scale 120 for measuring the position of table 106 in the Y-axis direction.

[0013] The X-axis slider 108 is mounted to reciprocate along a pair of X-axis guide rails (not shown) extending in the X-axis direction on the front surface of the upper portion of the column 104. The column 104 is equipped with an X-axis feed device that drives the X-axis slider 108 to reciprocate along the X-axis guide rails, which includes a ball screw (not shown) extending in the X-axis direction and an X-axis servo motor Mx connected to one end of the ball screw. The X-axis slider 108 is fitted with a nut (not shown) that engages with the ball screw. The column 104 is also fitted with an X-axis scale 116 for measuring the position of the X-axis slider 108 in the X-axis direction.

[0014] The spindle head 110 is mounted on the front of the X-axis slider 108 so as to be able to reciprocate along a pair of Z-axis guide rails that extend in the Z-axis direction (vertical direction in Figure 1). The X-axis slider 108 is equipped with a Z-axis feed device that drives the spindle head 110 to reciprocate along the Z-axis guide rails, which includes a ball screw (not shown) extending in the Z-axis direction and a Z-axis servo motor Mz connected to one end of the ball screw. A nut (not shown) that engages with the ball screw is attached to the spindle head 110. The X-axis slider 108 is also equipped with a Z-axis scale 118 for measuring the position of the spindle head 110 in the Z-axis direction.

[0015] The servo motors (X-axis servo motor Mx, Y-axis servo motor My, Z-axis servo motor Mz) 140 for each of the X-axis, Y-axis, and Z-axis feed axes, and the X-axis scale 116, Y-axis scale 120, and Z-axis scale 118 are connected to the control device 150 of the machine tool 100. The imaging device 30 is also connected to the control device 150. The control device 150 includes an NC device that controls the power (current value) supplied to the servo motors (X-axis servo motor Mx, Y-axis servo motor My, Z-axis servo motor Mz) 140 for each of the X-axis, Y-axis, and Z-axis feed axes.

[0016] The control panel 200 includes a display panel 202 that forms the display device 28 (Figure 4) of the measuring device, which will be described later. In this embodiment, the display panel 202 can be formed as a touch panel that allows the operator to select a part of the screen or input a corresponding part by touching the screen with their finger or a stylus. The control panel 200 includes a key input section 204. The key input section 204 has a plurality of key switches. By pressing the key switches of the key input section 204, predetermined numbers or characters can be entered. The control panel 200 may also include an operation switch (not shown) for selecting a predetermined operation, an override setting section (not shown) for setting override values, and an emergency stop button (not shown). The override setting section can, for example, set override values ​​for the spindle rotation speed or the machining feed rate.

[0017] The machine tool 100 is further equipped with a manual pulse generator 50, which is a manual operation unit for the operator to manually input commands to the servo motors (X-axis servo motor Mx, Y-axis servo motor My, Z-axis servo motor Mz) 140 of the X-axis, Y-axis, and Z-axis feed axes. The machine tool 100 is equipped with a manual pulse generator 50 connected to the control panel 200. The manual pulse generator 50 is provided so that the servo motors (X-axis servo motor Mx, Y-axis servo motor My, Z-axis servo motor Mz) 140 of the X-axis, Y-axis, and Z-axis feed axes, which are normally driven based on commands from the control device (NC device) 150, can be manually driven as needed by sending command pulses. For this reason, the manual pulse generator 50 is configured to send command pulses. Instead of the manual pulse generator 50, manual operation may be performed using an operating device that performs jog feed.

[0018] The machine tool 100 can further be a machining center equipped with peripheral equipment such as a tool magazine (not shown) that stores multiple tools used for machining, an automatic tool changer 40 that exchanges tools between the tool magazine and the spindle 112, and a coolant supply device (not shown) that supplies coolant to the machining area of ​​the machine tool 100, as well as a machine control device that controls the peripheral equipment. The control device 150 may include a machine control device.

[0019] A workpiece measuring device 10 is connected to the control device 150. The main components of the control device are a processing unit 12, a data storage unit 14, an input unit 24, a display control unit 26, a display device 28, and an imaging device 30. The data storage unit 14 includes a measurement program storage unit 16, a measurement point coordinate storage unit 18, a measurement target storage unit 20, and a measurement information storage unit 22.

[0020] The workpiece measuring device 10, particularly the processing unit 12, data storage unit 14, and display control unit 26, can be composed of a computer and related software including a CPU (central processing element), memory devices such as RAM (random access memory) and ROM (read-only memory), storage devices such as HDD (hard disk drive) and SSD (solid state drive), input / output ports, and a bidirectional bus that interconnects them. The processing unit 12, data storage unit 14, and display control unit 26 can be configured as software as part of the control device 150 of the machine tool 100 shown in Figure 1, particularly as part of an NC device or machine control device. As will be described later, the data storage unit 14 can store, in addition to measurement information, a pre-stored reference position of the workpiece W and image data captured by the imaging device 30, linked to the reference position of the workpiece.

[0021] The processing unit 12 performs processing according to the flowchart described later. The input unit 24 can be formed by, for example, a touch panel, a key input unit 204, a plurality of key switches, etc., which constitute the display panel 202 of the control panel 200 of the machine tool 100 shown in Figure 1. The display device 28 can be formed by, for example, the display panel 202 of the control panel 200 of the machine tool 100 shown in Figure 1. The display control unit 26 generates a screen to be displayed on the display device 28 according to commands from the processing unit 12.

[0022] The imaging device 30 can be formed by, for example, a digital color camera mounted on the spindle 112 of the machine tool 100 shown in Figure 1. The imaging device 30 is connected to the processing unit 12 by a wired communication means such as Ethernet compliant with IEEE 802.3 or a wireless communication means such as a wireless LAN compliant with IEEE 802.11 or Bluetooth® compliant with IEEE 802.15.1.

[0023] The X-axis, Y-axis, and Z-axis motors 34 can be formed by the servo motors (X-axis servo motor Mx, Y-axis servo motor My, Z-axis servo motor Mz) 140 of the feed axes of the X-axis, Y-axis, and Z-axis of the machine tool 100 shown in Figure 1. The X-axis, Y-axis, and Z-axis scales 36 can be formed by the X-axis scale 116, the Y-axis scale 120, and the Z-axis scale 118.

[0024] The following describes the workpiece measurement method on the machine tool 100 according to this embodiment. Referring to Figure 4, the screen displayed on the display device 28, window 300, is shown, and window 300 includes a plurality of function buttons 302, 304, 308, and 310, including a workpiece measurement button 306. When the operator taps the workpiece measurement button 306, workpiece measurement is started according to the flowchart in Figure 3 (step S10), and the workpiece measurement window 312 is displayed in window 300.

[0025] As one example, the work measurement window 312 includes a new button 314, an edit button 316, and an execute button 318. The work measurement window 312 may also include text describing the content of each button, adjacent to the new button 314, the edit button 316, and the execute button 318, as shown in Figure 4.

[0026] When the work measurement window 312 is displayed on the display device 28, the flowchart waits for the operator to select and tap one of the new button 314, edit button 316, and execute button 318 (step S12). That is, if the operator taps the new button 314, it is determined that no measurement information has been registered (No in step S12), and the flowchart proceeds to step S14. If the operator taps the execute button 318, it is determined that there is already registered measurement information (Yes in step S12), and the flowchart proceeds to step S36.

[0027] When the operator taps the new button 314 (No in step S12), the flowchart proceeds to step S14, and a measurement information creation dialog box 320 prompting the operator to create measurement information is displayed in the work measurement window 312. The measurement information creation dialog box 320 can display text declaring that new measurement information will now be created. In the example in Figure 5, the measurement information creation dialog box 320 includes the text, "The following measurement information will be created."

[0028] The measurement information creation dialog box 320 also includes a number box 322, a comment box 324, and an input confirmation button 326. The number box 322 allows the user to enter a unique number to be assigned to the newly created measurement information. The comment box 324 allows the user to enter text that allows the operator to understand the content of the measurement information, such as the name of the workpiece measured using the measurement information.

[0029] The measurement information is described below. The measurement information is information related to the measurement necessary to carry out the workpiece measurement method of the present invention, and may include, as an example, the machine coordinate values ​​of the camera when measuring, the shape of the object to be measured (mark or hole) when measuring a template, the number of objects to be measured, the method for calculating the measurement center (for example, in the case of two-point measurement, whether to use one of the points or the midpoint of the two points), the method for calculating the inclination (for example, which two points to use in the case of three-point measurement), macro variables to which the machine coordinate values ​​(X, Y) of the measurement points should be registered, comments to be attached to the macro variables, etc.

[0030] The measurement target is a feature provided on the workpiece surface that indicates the reference position of the workpiece to be measured. In the embodiments described below, the measurement target includes a circular hole formed in the workpiece, a circular alignment mark (circular alignment mark) provided on the surface of the workpiece, an alignment mark of an arbitrary shape other than circular (non-circular alignment mark), and the edge of the workpiece. Of these, the circular hole, the circular alignment mark, and the edge of the workpiece are measurement targets with typical shapes and can be stored in advance in the measurement target storage unit 20.

[0031] If the object to be measured is a non-circular alignment mark with a shape other than a circle, it is necessary to register the non-circular alignment mark as a template in the measurement object storage unit 20. In this application, the measurement performed using a non-circular alignment mark registered in the measurement object storage unit 20 as a template is called "template measurement". In template measurement, the operator manually moves the main spindle 112 and the table 106 relative to each other in the X and Y directions so that the alignment mark of an arbitrary shape to be used as a reference is positioned at the center of the image captured by the imaging device (camera), and the coordinates of the center of the alignment mark of the arbitrary shape are measured, and the coordinate values ​​of the reference point of the arbitrary shape are stored as the measurement result. In this way, the mechanical coordinate values ​​of the center position obtained by template measurement can be used as the reference point of the alignment mark when the alignment mark is registered as a template.

[0032] The measurement information may also include, as setting parameters for the imaging device (camera), parameters (flags) for manually or automatically setting the exposure time of the imaging device, the exposure time when manually set, parameters (flags) for manually or automatically setting the gain of the imaging device, the measurement center, the work offset for registering the tilt, parameters (flags) for determining whether or not to register the measurement center and tilt to the work offset, the offset amount when registering the measurement center and tilt to the work offset, the minimum and maximum diameters of the hole to be measured if the measurement target is a hole, and the minimum and maximum contrasts when extracting the hole to be measured.

[0033] The measurement information may further include the width (length in the X-axis direction) and height (length in the Y-axis direction) of the area where the non-circular alignment marks are placed in the case of template measurement, as well as the minimum and maximum contrast values ​​when creating the marks as a template.

[0034] The operator enters a number in the number box 322, enters text in the comment box 324, and then taps the input confirmation button 326 to open the measurement information input window 328. As an example, the measurement information input window 328 shown in Figure 6 includes an origin calculation method selection box 332, an origin measurement method input box 334, an inclination calculation method input box 336, a setting confirmation box 338, and a measurement result registration box 340.

[0035] The origin calculation method selection box 332 includes a one-point measurement button 332a, a two-point measurement button 332b, and a three-point measurement button 332c. The one-point measurement button 332a is used when one measurement point is used as the origin. The two-point measurement button 332b is used when the midpoint of two points is used as the origin. The three-point measurement button 332c is used when the center of three points on the circumference is used as the origin. There are five types of calculation methods: using one measurement point as the origin, using the midpoint of two points as the origin, using the center of three points on the circumference as the origin, using the vertices of three points on a rectangle as the origin, and using four measurement points as the origin.

[0036] The origin measurement method input box 334 is used to select the calculation method of the workpiece coordinate system offsets Y and Y from a drop-down list. The inclination calculation method input box 336 is used to input the calculation method of the inclination angle of the workpiece with respect to the X-axis in the X-Y plane. For example, the calculation method of the inclination may be the inclination angle with respect to the X-axis or also the inclination angle with respect to the Y-axis. For example, "for the first point P1(X ｐ１ , Y ｐ１ ) and the second point P2(X ｐ２ , Y ｐ２ ), the angle θ of the straight line connecting them is θ = ACOS((X ｐ１ - X ｐ２ ) / ((X ｐ１ - X ｐ２ ) ２ + (Y ｐ１ - Y ｐ２ ) ２ )) １／２ ).

[0037] In the setting confirmation box 338, the setting of the measurement information newly created is shown graphically. In the example of FIG. 6, it is shown that one measured point is set as the origin of the workpiece in the X-Y plane. The measurement result registration box 340 includes a macro variable input box 340a for the measurement result registration destination and a comment input box 340b. In the example of FIG. 6, it is shown that the X coordinate value and the Y coordinate value of one measured point are registered in the macros indicated by 100 and 101, respectively.

[0038] After the operator inputs the necessary values into each input box in the measurement information input window 328 through the input unit 24, and then taps the measurement button 342, the manual measurement window 344 (FIG. 7) opens. By opening the camera condition setting tab 346 of the manual measurement window 344, the conditions of the imaging device (camera) as measurement information can be set. In the example of FIG. 7, the camera condition setting tab 346 includes an exposure time selection box 346a for selecting whether the system automatically sets the exposure time setting as the imaging device condition or the operator manually sets it, and a gain selection box 346b for selecting whether to set the gain of the imaging device manually or automatically.

[0039] After setting the conditions of the imaging device, by opening the detection condition tab 348, it becomes possible to set the measurement target. The detection condition tab 348 includes a plurality of measurement target selection buttons for selecting the measurement target. In the example shown in FIG. 8, the measurement target selection buttons include a hole button 348a, a circular contour button 348b, a template measurement button 348c, and an edge button 348d.

[0040] When the hole button 348a is tapped, the hole (round hole) formed in the workpiece is selected as the measurement target. When the circular contour button 348b is tapped, the circular alignment mark provided on the workpiece surface is selected as the measurement target. At this time, a predetermined frame that can surround the measurement target may be displayed in the manual measurement window 344. This frame is referred to as a template frame and is shown as a rectangular frame 210 in FIG. 11, for example. When the template measurement button 348c is tapped, a non-circular alignment mark having a shape other than a circle provided on the workpiece surface is selected as the measurement target. When the edge button 348d is tapped, the edge of the workpiece is selected as the measurement target.

[0041] The circular hole, circular alignment mark, and edge as the measurement targets are already registered and stored in the measurement target storage unit 20. The non-circular alignment mark is a measurement target arbitrarily registered by the operator. When the detection condition tab 348 is opened, the flowchart determines whether it is template measurement in step S15.

[0042] As an example, when the hole button 348a is tapped, the already registered hole is selected as the measurement target. Since the measurement of the hole is not "template measurement" using the non-circular alignment mark as a template, the determination in step S15 is No, and the flowchart proceeds to step S18. At this time, the workpiece surface imaged by the imaging device 30 is displayed in the image display area 350 (FIG. 9). The image of the workpiece surface includes a circular hole 361.

[0043] In step S18, the operator, while viewing the image of the workpiece surface displayed in the image display area 350, uses the manual pulse generator 50 to move the spindle 112 and table 106 of the machine tool 100 relative to each other in the X and Y directions so that the center Om of the hole 361 to be measured is near the intersection Oc of the cross lines. The imaging device 30 is pre-adjusted so that when it is mounted on the spindle 112, the intersection Oc of the cross lines is positioned on the rotation axis of the spindle 112 of the machine tool 100.

[0044] When aligning the center Om of the circular hole 361 with the intersection Oc of the cross lines, the actual center Om of the hole 361 is not displayed, so the intersection Oc of the cross lines and the center Om of the hole 361 are in a temporary position that does not necessarily coincide. Next, when the operator taps the detection button 372, the processing unit 12 detects the hole 361 in the image data captured by the imaging device 30, reads the coordinate values ​​of the intersection Oc of the cross lines from the X-axis scale 116 and Y-axis scale 120, and calculates the coordinate values ​​of the center Om of the hole 361. Based on the calculated coordinate values ​​of the center Om of the hole 361 in the image data, the X-axis and Y-axis feed axes are automatically driven until the center Om of the circular hole 361 coincides with the intersection Oc of the cross lines. The coordinate values ​​of the intersection Oc of the cross lines are read from the X-axis scale 116 and Y-axis scale 120 and obtained as the coordinate values ​​of the center Om of the circular hole 361. The coordinate values ​​of the center Om of the obtained circular hole 361 are stored in the measurement point coordinate storage unit 18 as the coordinate values ​​of the reference point of the hole 361 that is the object of measurement (step S20), and are also displayed in the measurement result display area 352 as the measurement result.

[0045] If the operator taps the circular contour button 348b in step S15, the object to be measured is a circular alignment mark. Since measurement using a circular alignment mark is not a "template measurement," the determination in step S15 is No, and the flowchart proceeds to step S18. At this time, the work surface captured by the imaging device 30 is displayed in the image display area 350 (Figure 10). The image of the work surface includes the circular alignment mark 363.

[0046] In step S18, the operator, while viewing the image of the workpiece surface displayed in the image display area 350, uses the manual pulse generator 50 to move the spindle 112 and table 106 of the machine tool 100 relative to each other in the X and Y directions so that the center Om of the circular alignment mark 363 is near the intersection point Oc of the cross lines.

[0047] Next, when the operator taps the detection button 372, the processing unit 12 detects the circular alignment mark 363 in the image data captured by the imaging device 30, reads the coordinate values ​​of the intersection point Oc of the cross lines from the X-axis scale 116 and Y-axis scale 120, and calculates the coordinate values ​​of the center Om of the circular alignment mark 363. Based on the calculated coordinate values ​​of the center Om of the circular alignment mark 363 in the image data, the X-axis and Y-axis feed axes are automatically driven until the center Om of the circular hole 363 coincides with the intersection point Oc of the cross lines. The coordinate values ​​of the intersection point Oc of the cross lines are read from the X-axis scale 116 and Y-axis scale 120 and acquired as the coordinate values ​​of the center Om of the circular alignment mark 363. The obtained coordinate values ​​of the center Om of the circular alignment mark 363 are stored in the measurement point coordinate storage unit 18 as the reference point of the circular alignment mark 363 that is the object of measurement (step S20), and are displayed in the measurement result display area 352 as the measurement result.

[0048] Even if the operator selects an edge as the measurement target in step S15 and taps the edge button 348d, the determination in step S15 will be No, and the flowchart proceeds to step S18. The work surface captured by the imaging device 30 is displayed in the image display area 350. The image of the work surface includes the edge portion of the work (not shown).

[0049] In step S18, the operator uses the manual pulse generator 50 to move the spindle 112 and the table 106 relative to each other in the X and Y directions, while viewing the image of the work surface displayed in the image display area, so that the intersection of the cross lines is positioned on the edge of the work to be measured.

[0050] Next, when the operator taps the detection button 372, the processing unit 12 detects the edge of the workpiece in the image data captured by the imaging device 30, reads the coordinate values ​​of the intersection point Oc of the cross lines from the X-axis scale 116 and the Y-axis scale 120, and calculates the coordinate values ​​of the workpiece edge. The calculated coordinate values ​​of the workpiece edge are stored in the measurement point coordinate storage unit 18 (step S20) and are displayed as measurement results in the measurement result display area 352.

[0051] Since the edges of the workpiece are straight lines, the coordinate values ​​of the edges will be either the X coordinate or the Y coordinate. In other words, when the processing unit 12 detects an edge of the workpiece, if the detected edge extends in the X-axis direction, the Y coordinate will be the coordinate value of the edge, and if the detected edge extends in the Y-axis direction, the X coordinate will be the coordinate value of the edge.

[0052] In step S15, when the operator taps the template measurement button 348c, the processing unit 12 determines that template measurement has been selected (Yes in step S15), and the flowchart proceeds to step S16. At this time, the image display area 350 displays the work surface captured by the imaging device 30. In the example in Figure 11, the image of the work surface includes a cross-shaped alignment mark 360 as a non-circular alignment mark.

[0053] If a non-circular alignment mark is registered as the target of measurement (if the answer is Yes in step S16), the operator uses the manual pulse generator 50 to move the spindle 112 and table 106 relative to each other in the X and Y directions, while viewing the image of the work surface displayed in the image display area 350, so that the center Om of the non-circular alignment mark 360 to be measured is near the intersection point Oc of the cross lines displayed in the template frame 210 (step S18). In other words, when the operator operates the manual pulse generator 50 in step S16, the processing unit 12 determines that a non-circular alignment mark 360 is registered as the target of measurement. The information registered in the processing unit 12 is image data of the non-circular alignment mark 360 and position information on the image data indicating which position in the image is the center Om of the non-circular alignment mark 360.

[0054] Next, when the operator taps the detection button 372, the processing unit 12 extracts the same shape as the registered non-circular alignment mark 360 from the image of the captured work surface, and automatically drives the X-axis and Y-axis feed axes until the center Om of the non-circular alignment mark 360 on the captured work surface coincides with the intersection point Oc of the cross lines. The coordinates of the intersection point Oc of the cross lines are read from the X-axis scale 116 and the Y-axis scale 120.

[0055] When aligning the center Om of the non-circular alignment mark 360 with the intersection Oc of the cross lines displayed within the template frame 210, it is ideal that the intersection Oc and the center Om coincide, as shown in Figure 12. However, in reality, the center Om of the non-circular alignment mark is not shown in the displayed image, and the operator manually moves the spindle 112 and the table 106 relative to each other in the X and Y directions using the manual pulse generator 50. Therefore, as illustrated in Figure 13, the intersection Oc of the cross lines and the center Om of the non-circular alignment mark 360 are in temporary positions that do not necessarily coincide.

[0056] The processing unit 12 reads the coordinate values ​​of the intersection point Oc of the cross lines from the X-axis scale 116 and the Y-axis scale 120, stores them in the measurement point coordinate storage unit 18 as reference points for the non-circular alignment marks 361 (step S20), and displays the measurement results in the measurement result display area 354.

[0057] After the measurement results are stored in step S20, the operator taps the proceed button 356, which displays the registration dialog box 358 (Figure 14). When the operator taps the OK button 358a in the registration dialog box 358, the measurement results are stored and registered in the measurement information storage unit 22 (step S22), and the flowchart proceeds to step S30. At this time, the manual measurement window 344 (Figure 7) is displayed again on the display device 28.

[0058] In step S30, if the measurement of all measurement targets has not been completed and there are still measurement targets that need to be registered, the operator taps the hole button 348a, the circular contour button 348b, or the edge button 348d of the measurement target selection buttons in the manual measurement window 344. As a result, the processing unit 12 determines that not all measurement targets have been measured. In other words, the determination in step S30 is No, and the flowchart returns to step S15.

[0059] In this way, steps S15 to S22 are repeated until measurements are completed for all measurement targets. When measurements are completed for all measurement targets, the operator taps the advance button 356, the determination in step S30 becomes Yes, the measurement information and measurement results are displayed in the measurement information window 370 (Figure 15), the measurement information and measurement results are stored and registered in the measurement information storage unit 22 (step S32), and the manual measurement process ends (step S34).

[0060] When registering a non-circular alignment mark as a new measurement target, the operator taps the template measurement button 348c (Figure 11). The processing unit 12 determines that template measurement has been selected because the template measurement button 348c has been tapped (Yes in step S15), and determines that no measurement target has been registered (No in step S16).

[0061] Thus, the flowchart proceeds to step S24. As shown in Figure 16, the workpiece surface captured by the imaging device 30 is displayed in the image display area 350. In the example in Figure 16, the non-circular alignment mark 362 to be newly registered has an equilateral triangle shape.

[0062] Next, the operator, while viewing the image of the work surface displayed in the image display area, uses the manual pulse generator 50 to manually move the spindle 112 and the table 106 relative to each other in the X and Y directions so that the position to be set as the center Om of the non-circular alignment mark 362 to be registered aligns with the intersection Oc of the cross lines (step S24).

[0063] Next, by tapping the "Create New" button 368, a non-circular alignment mark 362 (an equilateral triangle in the example of Figure 16) to be registered is extracted from the image of the captured work surface and placed within the template frame 210. The intersection point Oc of the cross lines and the centroid of the equilateral triangle, which is the non-circular alignment mark 362, do not necessarily have to coincide; the position of the intersection point Oc of the cross lines within the extracted alignment mark is used as the reference point for the non-circular alignment mark 362.

[0064] Next, when the detection button 372 (Figure 11) is tapped, the processing unit 12 stores and registers the shape (an equilateral triangle in the example of Figure 16) and center position (the position of the center Om on the image) of the alignment mark 362 as a new non-circular alignment mark in the measurement target storage unit 20 (step S22). The processing unit 12 further reads the coordinates of the intersection point Oc of the cross lines from the X-axis scale 116 and the Y-axis scale 120, and based on the coordinate value of the center Om of the non-circular alignment mark 362 on the image data, the X-axis and Y-axis feed axes are automatically driven until the center Om of the non-circular alignment mark 362 matches the intersection point Oc of the cross lines. The coordinate value of the intersection point Oc of the cross lines is read from the X-axis scale 116 and the Y-axis scale 120 and obtained as the coordinate value of the center Om of the non-circular alignment mark 362. The coordinate values ​​of the center Om of the obtained non-circular alignment mark 362 are stored in the measurement point coordinate storage unit 18 as the coordinate values ​​of the reference point of the non-circular alignment mark 362 that is the object of measurement (step S22), and are also displayed in the measurement result display area 364.

[0065] If measurement information is registered (if the answer is Yes in step S12), the operator can perform workpiece measurement using the measurement program based on the registered measurement information, as described below.

[0066] When the work measurement window 312 is displayed, if the operator taps the execute button 318, in step S12, the processing unit 12 determines that measurement information has been registered, and the registered measurement information list window 380 (Figure 17) is displayed. Next, if the operator selects one or more measurement information from the registered measurement information list window 380 and taps the select button included in the detection conditions tab 348, the setup window 382 (Figure 18) opens. At this time, the corresponding measurement information is read from the measurement information storage unit 22, and the measurement program corresponding to the measurement information is read from the measurement program storage unit 16, and an image representing the operation of the machine tool 100 according to the measurement information and measurement program is displayed in the setup window 382.

[0067] Figure 18 shows the setup window as an example when registered measurement information No. 1 is selected. In this example, one measurement target on the workpiece surface (hole, circular alignment mark, or non-circular alignment mark) is measured. In other words, the imaging device 30 moves above the workpiece to a position above the reference point of the measurement target (a position receding along the Z axis), then moves 130 mm down along the Z axis to approach the workpiece, takes an image and measurement, and then moves 100 mm away from the workpiece along the Z axis (up). Furthermore, the fact that measurement information is registered means that measurement has already been completed for workpieces of the same shape while inputting measurement information, and this assumes a second or subsequent workpiece of the same shape. Even when measuring workpieces of the same shape, the X and Y axis positions of the measurement targets on the workpiece surface will be shifted for each workpiece due to errors when mounting the workpiece to the table 106.

[0068] When the operator confirms the measurement information to be performed in the setup window 382 and taps the confirmation (yes) button 384, a pop-up window 386 (Figure 19) appears prompting the operator to press the cycle start switch (not shown) located on the control panel 200. When the operator presses the cycle start switch located on the control panel 200, the imaging device 30 moves to a predetermined measurement position according to the measurement program (step S14), performs the measurement, and the measurement result is stored in the measurement point coordinate storage unit 18 (step S40). The operator repeats steps S36 to S40 until the measurement is completed for all measurement targets (no in step S42).

[0069] For example, as shown in Figures 20 to 23, if the workpiece to be measured has three non-circular alignment marks 362-1, 362-2, 362-3, and 362-4 on its surface, the measurement program can measure the positions of the centers Om-1, Om-2, Om-3, and Om-4 of the three non-circular alignment marks 362-1, 362-2, 362-3, and 362-4 one by one.

[0070] Prior to step S20 described above, the operator manually fine-tunes the mechanical coordinate values ​​(X, Y) of the measurement point to position the hole or alignment mark approximately at the center of the camera image before performing the measurement (step S18). Based on the measurement result of manually aligning the measurement point of the hole or alignment mark approximately at the center of the camera image beforehand, the camera position is automatically fine-tuned so that the measurement point is at the center of the camera image. This allows for accurate measurement without being affected by errors in the field of view size of the digital camera, which is the imaging device 30, or aberrations of the camera lens. Furthermore, as mentioned above, whether the operator can manually align the measurement point of the hole or alignment mark to the center of the camera image can vary depending on the operator's skill. Therefore, in the present invention, the measurement point is manually roughly aligned to the center of the camera image beforehand, and then the measurement is performed after automatically fine-tuning the measurement point to be at the center of the camera image. In other words, by performing multiple measurements, accurate measurement results that are not affected by the operator's skill can be obtained.

[0071] According to this embodiment, even if measurement information related to the object to be measured is not registered, for example, when processing a new workpiece that has not been processed before with the machine tool 100, the imaging device 30 is moved above the workpiece W by manual operation so that the object to be measured is positioned approximately in the center within the field of view of the imaging device 30, the object to be measured is extracted from the image of the workpiece surface captured, its center coordinates are determined and stored in the measurement information storage unit 22. Therefore, for workpieces to be measured using the same measurement information, for example, the second and subsequent workpieces W, a measurement program corresponding to the measurement of the workpiece W is generated based on the measurement information read from the measurement information storage unit 22, enabling automatic measurement.

[0072] Furthermore, while it is obvious that the center of a hole formed in a workpiece is the measurement point, in the case of alignment marks, the location of the measurement point varies depending on the shape of the mark. By using template measurement with images captured by an imaging device (camera) that can register the shape of the alignment mark and the measurement point of the alignment mark, the position of the machine coordinate value can be determined. Therefore, unlike conventional methods, there is no need to prepare CAD drawing data of the alignment mark in advance, and the shape of the alignment mark and the measurement point can be easily taught to the system.

[0073] 10 Workpiece measuring device 12 Processing unit 14 Data storage unit 16 Measurement program storage unit 18 Measurement point coordinate storage unit 20 Measurement target storage unit 22 Measurement information storage unit 24 Input unit 26 Display control unit 28 Display device 30 Imaging device 50 Manual pulse generator 100 Machine tool 102 Bed 102 Bed 104 Column 106 Table 108 X-axis slider 110 Spindle head 112 Spindle 140 Feed axis servo motor 150 Control device (NC device) 200 Operation panel 202 Display panel 204 Key input unit

Claims

1. A machine tool comprising: a spindle for mounting a tool; a table facing the spindle and for mounting a workpiece; a feed axis for relative movement between the spindle and the table; an imaging device that can be attached to the spindle of the machine tool and for imaging the surface of a workpiece fixed to the table; a display device for displaying the image of the workpiece surface captured by the imaging device; and a processing unit for extracting a target for measurement from the image data of the workpiece surface captured by the imaging device and calculating the coordinate values ​​of the reference point of the target for measurement. The processing unit is characterized in that, when the center of the target for measurement is positioned relative to the table at a temporary position within the range of the image of the workpiece surface displayed on the display device, the processing unit determines the position of the reference point of the target for measurement on the image data of the workpiece surface captured by the imaging device attached to the spindle, moves the feed axis relative to the table so that the measurement point of the target for measurement becomes the center position of the image captured by the imaging device, and measures the coordinate values ​​of the feed axis as the coordinate values ​​of the reference point of the target for measurement.

2. The machine tool according to claim 1, wherein the processing unit further stores the coordinate values ​​of the reference point of the object to be measured in the data storage unit, reads the coordinate values ​​of the object to be measured from the data storage unit after the workpiece has been replaced with a new workpiece, generates a measurement program using the coordinate values ​​as the temporary position of the new workpiece, and measures the new workpiece according to the measurement program.

3. The machine tool according to claim 1, wherein the object to be measured is a hole formed in the workpiece, a circular alignment mark provided on the surface of the workpiece, or the edge of the workpiece, and further comprises a manual operation unit for an operator to control the feed axis in manual operation mode, and the positioning to the temporary position is positioning by the manual operation unit.

4. The machine tool according to claim 1, wherein the object to be measured is an alignment mark of any shape provided on the surface of the workpiece.

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