Machine tool

Abstract

This machine tool comprises: a workpiece spindle device for applying rotation to a workpiece gripped by a spindle chuck; a turret device in which a turret tool rest, to which a plurality of turret tools can be detachably attached, can be indexed by turning around a rotation axis parallel to the main shaft of the workpiece spindle device and in which the indexed turret tool is positioned by movement; a control device that drives and controls the workpiece spindle device and the turret device; and an automatic origin establishment system in which an origin establishment master having a circular hole formed as a measurement part is fixed to a tool mounting part of the turret tool rest for mounting the turret tool, by gripping a wireless touch probe in the spindle chuck, a stylus of the touch probe is brought into contact with the inner surface of the measurement part inserted relatively by driving the turret device, and the center coordinates of the measurement part are established as the origin in the control device on the basis of a trigger signal transmitted from the turret probe.

Description

machine tool

[0001] The present invention relates to a machine tool equipped with an automatic origin establishing system for a turret device that is equipped with a plurality of turret tools.

[0002] In an NC lathe, precise control of the relative positional relationship between the workpiece and the tool is required to ensure that the machined workpiece falls within dimensional tolerances. Centering is performed between the workpiece's spindle and the turret tool post on which the tool is mounted. Patent Document 1 below discloses a centering method for a turret tool post in a machine tool. The conventional centering method described in this document measures the amount of misalignment between the center line of a centering jig attached to the turret tool post and the axis of the spindle, using the center line of the centering jig as a reference line. In this measurement, the probe of a dial gauge attached to the spindle is placed against the measurement circumferential surface of the centering portion. If the needle of the dial gauge deflects, the direction and amount of misalignment are confirmed, and a centering adjustment is performed on the turret device to eliminate the misalignment.

[0003] International Publication No. WO2017-126044

[0004] In the above-mentioned conventional example, centering can be easily measured using a centering jig attached to the turret tool post and a dial gauge attached to the spindle. However, this requires the operator to directly check the measurement status and read the direction and amount of misalignment based on the runout of the dial gauge, thereby adjusting the centering, which requires the operator to have experience and is a time-consuming task. Furthermore, the origin of the turret tool post obtained by centering adjustment is set at a position where its rotation axis and the center of the spindle are perpendicular to each other, but in other machine tools, the rotation axis of the turret tool post is configured to be parallel to the central axis of the spindle.

[0005] SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a machine tool equipped with an automatic origin establishment system for a turret device.

[0006] In one aspect of the present invention, a machine tool comprises a work spindle unit that imparts rotation to a workpiece gripped by a spindle chuck; a turret unit in which a turret tool post to which a plurality of turret tools can be attached and detached can be indexed by rotating about a rotation axis parallel to the spindle of the work spindle unit, and which positions the indexed turret tool by moving in a predetermined direction during machining; a control unit that controls the drive of the work spindle unit and the turret unit; and an origin establishment master having a circular hole formed as a measuring portion, which is fixed to the tool mounting portion of the turret tool post to which the turret tools are attached, and a wireless touch probe is held by the spindle chuck, so that the stylus of the touch probe is brought into contact with the inner surface of the relatively inserted measuring portion by driving the turret unit, and the control unit establishes the center coordinates of the measuring portion as an origin based on a trigger signal sent from the touch probe.

[0007] According to the above configuration, the stylus of the touch probe is inserted relatively into the interior of the measurement section of the origin establishment master by driving a turret device in which the origin establishment master is fixed to the tool mounting section of the turret tool rest. Furthermore, a predetermined movement of the origin establishment master brings the stylus into contact with the inner surface of the measurement section, which causes the touch probe to send a trigger signal to the control device. The control device then calculates the center coordinates of the measurement section based on this trigger signal and establishes it as the origin. Therefore, measurements that were previously performed manually to establish the origin can be automated.

[0008] FIG. 1 is a perspective view showing the internal structure of the body of an embodiment of a machine tool. FIG. 2 is a block diagram showing a control system for controlling the machine tool. FIG. 3 is a simplified diagram showing an automatic origin establishment system for a turret device in a machine tool. FIG. 4 is a perspective view showing an implementation measurement situation of the automatic origin establishment system for the turret device. FIG. 5 is a simplified diagram showing a turret tool post that executes automatic origin establishment processing for the turret device. FIG. 6 is a diagram showing a flowchart of a program for automatic origin establishment processing for the turret device.

[0009] An embodiment of a machine tool according to the present invention will be described below with reference to the drawings. Fig. 1 is a perspective view of the machine tool of this embodiment, particularly showing the internal structure of the machine body. The machine tool 1 of this embodiment is a small NC lathe in which various processing devices for processing a workpiece are mounted on a slant-type bed 6. The upper surface of the bed 6 is tilted forward, and mounted thereon are a first workpiece spindle unit 3 that rotatably grips a workpiece, a second workpiece spindle unit 4 that is disposed opposite the first workpiece spindle unit 3 and also rotatably grips a workpiece, and a turret unit 5 that has a plurality of turret tools T.

[0010] A first work spindle device 3 is disposed on the left side in front of the bed 6, and a second work spindle device 4 is disposed on the opposite right side. The first and second work spindle devices 3, 4 have spindles that are horizontal and in the machine body width direction, and furthermore, the spindles are disposed coaxially. In this embodiment, the direction parallel to the spindles of the first and second work spindle devices 3, 4 (the left-right width direction of the bed 6) will be described as the Z axis. The second work spindle device 4, which is coaxial with the first work spindle device 3, is configured to move in the machine body width direction, which is parallel to the Z axis.

[0011] The first work spindle device 3 has a spindle rotatably mounted on a casing 11, and a spindle chuck 12 integral with the spindle is rotated by a spindle motor to impart rotation to the gripped workpiece. The second work spindle device 4 is similarly configured to have a rotatable spindle mounted on a casing 15, and a spindle chuck 16 integral with the spindle is rotated by a spindle motor. In the first work spindle device 3, the casing 11 is integral with a headstock 13, and the headstock 13 is fixed to the bed 6, but in the second work spindle device 4, the casing 15 is mounted on a slidable headstock 14 and is configured to move in the Z-axis direction.

[0012] Two guide rails 18 parallel to the Z-axis for the second workpiece spindle device 4 are fixed to the bed 6. The headstock 14 is mounted integrally on a spindle table 17, and a guide block is fixed to the underside of the spindle table 17. The guide block engages with the guide rails 18 to form a linear guide. A screw shaft 19 parallel to the Z-axis is journaled between the two guide rails 18, and the rotation shaft of a Z-axis servo motor 20 is connected to the screw shaft 19. A nut member through which the screw shaft 19 passes is fixed to the underside of the spindle table 17, and a ball screw mechanism is formed in which the rotation output of the Z-axis servo motor 20 causes the spindle table 17 to move linearly in the Z-axis direction.

[0013] A turret device 5 is disposed behind the second workpiece spindle device 4. The turret device 5 has a disk-shaped turret tool rest 21 to which multiple turret tools T are attached at equal intervals in the circumferential direction, and the turret tool T to be used for machining is indexed by the rotation of the turret device 5. The turret tool rest 21 of the turret device 5 is configured to move in the Z-axis direction, a vertical direction perpendicular to the Z-axis, and a 45-degree direction that coincides with the inclination of the upper surface of the bed 6. In this embodiment, the direction of this vertical plane will be referred to as the Y-axis, and the direction of inclination of the assembly surface will be referred to as the X-axis.

[0014] Two guide rails 23 parallel to the Z-axis are fixed to the right rear portion of bed 6, and a linear guide is formed by these and a guide block fixed to the underside of turret table 24. Turret table 24 is capable of moving in the Z-axis direction by a ball screw mechanism. That is, a screw shaft 25 parallel to the Z-axis is supported between the two guide rails 23 via bearings, and this screw shaft 25 passes through a nut member fixed to the underside of turret table 24. The rotating shaft of a Z-axis servo motor 26 is connected to the screw shaft 25, and the rotation output of this screw shaft moves turret table 24 linearly in the Z-axis direction.

[0015] A turret X-axis slide 27 is attached to the turret table 24 so as to slide on an X-axis guide rail formed on the upper surface of the turret table 24. A Y-axis guide rail is formed on the vertical front surface of the turret X-axis slide 27, and a turret main body 28, including the turret tool post 21 and the indexing servo motor 22, is attached to slide thereon. A screw shaft (not shown) connected to an X-axis servo motor 29 is supported on the turret table 24 via a bearing, and the screw shaft passes through a nut member fixed to the turret X-axis slide 27. Similarly, a screw shaft (not shown) connected to a Y-axis servo motor 30 is supported on the turret X-axis slide 27 via a bearing, and the screw shaft passes through a nut member fixed to the turret main body 28. Therefore, the rotational outputs of the X-axis servo motor 29 and the Y-axis servo motor 30 cause the turret X-axis slide 27 to move linearly in the X-axis direction, and the turret main body 28 to move linearly in the Y-axis direction.

[0016] 2 is a block diagram showing a control system for controlling the machine tool 1. A microprocessor (CPU) 41, a ROM 42, a RAM 43, and a non-volatile memory 44 are connected to the control device 8 of the machine tool 1 via a bus line. The CPU 41 controls the entire control device. The ROM 42 stores system programs and control parameters executed by the CPU 41, and the RAM 43 stores temporary calculation data, display data, and the like. The non-volatile memory 44 also stores information necessary for processing by the CPU 41, including the sequence program for the machine tool 1. The control device 8 is provided with an I / O port 45, through which the drive motors for the first and second workpiece spindle devices 3 and 4 and the turret device 5 are connected via their respective drivers. An operation and display device 48 attached to the front of the machine tool 1 is also connected to the control device 8 via the I / O port 45.

[0017] The machine tool 1 configured as described above is capable of a first machining operation on a workpiece on the first workpiece spindle device 3 side and a second machining operation on a workpiece on the second workpiece spindle device 4 side. In the first machining operation, the turret tool T indexed by the turret device 5 moves relative to the workpiece gripped by the chuck mechanism 12 under control in each axial direction. That is, the turret body 28 moves from right to left across the bed 6 along the Z axis, which is the width direction of the machine body, under drive control of the Z axis servo motor 26, and further moves in the longitudinal direction and vertical direction of the machine body along a combination of the X axis and Y axis under drive control of the X axis servo motor 29 and the Y axis servo motor 30. Then, outer diameter machining of the rotating workpiece using a cutting tool, hole drilling of a phased workpiece using a drill, and other operations are performed.

[0018] In the second machining, the second workpiece spindle device 4 is driven and controlled by the Z-axis servo motor 20 to move from right to left on the bed 6, and the chuck mechanism 16 receives the workpiece gripped by the chuck mechanism 12 of the first workpiece spindle device 3. At this time, the gripping state of the workpiece is reversed, and backside machining of the workpiece becomes possible in the second machining. The second workpiece spindle device 4, which has gripped the workpiece, is again driven and controlled by the Z-axis servo motor 20 to move from left to right in the machine body width direction and return to its original position. Then, as in the first machining, the turret body 28 is driven and controlled by the Z-axis servo motor 26 to move to the right side of the bed 6, and is also driven and controlled by the X-axis servo motor 29 and the Y-axis servo motor 30 to move in the machine body forward-backward and upward-downward directions. There, the workpiece is subjected to a predetermined machining operation, such as turning.

[0019] Incidentally, the machine tool 1 requires machining accuracy on the order of microns, and to achieve this, high positioning accuracy for the turret tool T during machining is necessary. Therefore, the machine tool 1 establishes an origin based on centering between the spindle chucks 12, 16 that grip the workpiece and the turret tool post 21 on which the turret tool T is mounted, so that the relative positional relationship between the workpiece and the turret tool T can be accurately controlled. In particular, the machine tool 1 is equipped with an automatic origin establishment system for the turret device 5 that establishes an origin through automatic measurement using a wireless touch probe. Furthermore, this automatic origin establishment system establishes an origin during indexing for the turret tool post 21 on which multiple turret tools T are mounted.

[0020] In the machine tool 1, the rotation axis of the turret tool post 21 in the turret unit 5 is parallel to the spindle axes of the first workpiece spindle unit 3 and the second workpiece spindle unit 4. Therefore, if there is an error in the radial dimension from the center of the turret tool post 21 to the multiple tool mounting units, the origin of the indexed turret tool T will not be consistent. Conventionally, to solve this problem, a method has been used in which test cutting is performed before establishing the origin, the cutting diameter is measured, and the resulting value is used to set the origin coordinates. However, this method is subject to significant individual variation based on the experience of the operator, and requires the preparation of non-cutting materials and tools, which increases costs, and furthermore, it takes time to establish the origin. Therefore, in this embodiment, a configuration is adopted in which the origin of the turret tool post 21 is automatically established for each of the multiple tool mounting units.

[0021] Fig. 3 is a simplified diagram showing the automatic origin establishment system for the turret unit 5 in the machine tool 1. Fig. 4 is a perspective view showing an implementation measurement situation of the automatic origin establishment system for the turret unit 5. In this system, a wireless touch probe 51 is held by the spindle chuck 12, and an origin establishment master 53 is attached to the tool mounting portion 211 of the turret tool rest 21. Note that while the establishment of the origin for the turret unit 5 during the first machining operation on the side of the first workpiece spindle unit 3 will be described here, the origin establishment during the second machining operation on the second workpiece spindle unit 4 is performed in a similar manner.

[0022] The origin establishment master 53 is a block that can be attached to and detached from the tool mounting portion 211 of the turret tool post 21, and has a circular hole formed as a measuring portion 531. The origin establishment master 53 attached to the tool mounting portion 211 has a center line O1 of the measuring portion 531 that is parallel to the rotation axis O2 of the turret tool post 21 and also parallel to the center line O3 of the spindle of the first workpiece spindle unit 3. The same origin establishment master 53 is attached to tool mounting portions 211 Nos. 1 to 12 formed on the turret tool post 21, as shown in Figure 5. Figure 5 is a simplified diagram of the turret tool post 21 that executes the automatic origin establishment process of the turret unit 5.

[0023] The touch probe 51 held by the spindle chuck 12 has a stylus 511 with a spherical contact at its tip that protrudes toward the origin establishment master 53. When the stylus 511 is inserted into the measuring section 531 and the contact comes into contact with the inner surface and tilts, a trigger signal is transmitted to the control device 8 at that moment. For this reason, a wireless transmitter is incorporated inside the body of the touch probe 51, and a receiver 55 for receiving the trigger signal from the touch probe 51 is connected to the control device 8.

[0024] In the automatic origin establishment process of the turret unit 5, the touch probe 51 is used to center with the origin establishment master 53, thereby calculating the origin positions for the twelve tool mounting portions 211 of the turret tool rest 21. In this centering process, on the side of the first workpiece spindle unit 3, the stylus 511 of the touch probe 51 held by the spindle chuck 12 protrudes and overlaps the center line O2 of the spindle. Then, on the turret unit 5 side, the indexed origin establishment master 53 is moved to the position shown in Figures 3 to 5 by drive control of the Z-axis servo motor 26, X-axis servo motor 29, and Y-axis servo motor 30, and the stylus 511 is relatively inserted into the measuring unit 531.

[0025] Thereafter, the turret device 5 drives the X-axis servo motor 29 and the Y-axis servo motor 30 for the tool post 21 to move, for example, the indexed No. 1 origin establishment master 53 in the orthogonal direction indicated by the arrow in Fig. 5. As a result, the inner surface of the measuring part 531 of the origin establishment master 53 comes into contact with the stylus 511 in each direction. At this time, a trigger signal indicating the contact position is transmitted via the wireless transmitter in accordance with the inclination of the stylus 511, and the coordinate values ​​at the time the trigger signal was received are recorded in the control device 8.

[0026] The center coordinates of the measuring unit 531 are calculated from the coordinate values ​​obtained by this centering operation, and these center coordinates are established as the origin of the turret tool post 21 for the indexed No. 1 tool mounting unit 211. Therefore, according to this automatic origin establishment system for the turret device 5, by establishing the origin using the wireless touch probe 51, it is possible to automate measurements that have previously been performed by an operator, significantly reducing the workload and obtaining results in a short time. Furthermore, it is possible to establish an appropriate origin regardless of the operator's experience.

[0027] Here, for the turret tool post 21 configured based on a regular dodecagon, the coordinate value determined for tool mounting portion 211 No. 1 should be the origin for tool mounting portions 211 No. 2 to No. 12. Therefore, the coordinate value obtained by a single origin establishment master 53 may be used as the origin. However, dimensional errors may occur in the turret tool post 21, and there are cases where a common origin cannot be used for the indexed tool mounting portions 211 No. 1 to No. 12. Therefore, in this embodiment, a configuration is adopted in which the origins of the turret tool post 21 are individually established for tool mounting portions 211 No. 1 to No. 12. In particular, the coordinate value of the centering position obtained for tool mounting portion 211 No. 1 is set as the origin reference value, and the amount of deviation for each of tool mounting portions 211 No. 2 to No. 12 is recorded as a correction value for the origin reference value.

[0028] 6 is a diagram showing a flowchart of the program for the automatic origin establishment processing of the turret device 5. In this automatic origin establishment processing, first, an operator holds the wireless touch probe 51 in the spindle chuck 12 and attaches the origin establishment masters 53 to the tool mounting portions 211 Nos. 1 to 12 of the turret tool rest 21. Thereafter, by pressing the automatic origin establishment button provided on the operation and display device 48, the automatic origin establishment program for the turret device 5 is executed by automatic control in the machine tool 1.

[0029] In this program, the origin coordinates are first calculated for the No. 1 tool mounting unit 211 as described above (S101). Next, the processing for the No. 2 and subsequent tool mounting units 211 is confirmed based on the number of processing times n (S102). The number of processing times n is preset to "1," and after the processing for the No. 1 tool mounting unit 211 is completed, n is "1" (S102: YES). In this case, the centering position calculated for the No. 1 tool mounting unit 211 is recorded as the origin reference value (S103). Thereafter, the centering processing is performed in the same manner for the No. 2 and subsequent tool mounting units 211 in order.

[0030] Each time one tool mounting unit 211 is processed, the value of the processing count n is incremented by "1" (S104), and it is determined whether or not the value exceeds "12" (S105). If it does not exceed "12" (S105: NO), the turret tool post 21 is rotated 30 degrees, and the tool mounting unit 211 with the number corresponding to the processing count n is identified (S106). For example, if the processing count n is "2," the origin establishment master 53 attached to the second tool mounting unit 211 is moved to a position overlapping with the spindle chuck 12 shown in FIG. 5. Then, the coordinate values ​​of the centering positions are calculated in the same manner (S101). Ideally, the coordinate values ​​of the centering positions of the first and second tool mounting units 211 should match, but a discrepancy may occur due to dimensional errors in the turret tool post 21.

[0031] Therefore, for the tool mounting units 211 Nos. 2 to 12 other than No. 1, which is the origin reference value (S102: NO), the error from the origin reference value is calculated as a correction value (S107), and this value is recorded as the correction value for No. 2 tool mounting unit 211 (S108). Thereafter, the value of the number of processing times n is incremented by "1" (S104), and correction values ​​are calculated and recorded for each of the indexed tool mounting units 211 Nos. 3 to 12 based on the centering process (S108). Then, when the value of the number of processing times n exceeds "12," which is the number of tool mounting units 211, and becomes "13" (S105: YES), the automatic origin establishment program ends.

[0032] Therefore, according to the automatic origin establishment system of the turret unit 5, origins are established for all of the tool mounting portions 211 Nos. 1 to 12 of the turret tool post 21 for the first machining, and these become the basis for creating the first machining program. Furthermore, the machine tool 1 not only performs the first machining, but also the second machining of a workpiece held by the second workpiece spindle unit 4 using the turret unit 5. Therefore, in the automatic origin establishment system of the turret unit 5, the touch probe 51 held by the spindle chuck 16 and the origin establishment master 53 attached to the turret tool post 21 perform the origin establishment process in the same manner in accordance with the automatic origin establishment process program.

[0033] As described above, according to this embodiment, the origin is established using the wireless touch probe 51. This significantly reduces the workload by automating measurements that were previously performed by an operator. In particular, even when establishing the origin of the tool post 21 for each index, the results can be obtained in a short time. In this regard, the machine tool 1 of this embodiment requires the origin to be established for both the first workpiece spindle unit 3 and the second workpiece spindle unit 4, significantly reducing the workload and shortening the time required for the operator. Furthermore, while the origin establishment previously required sufficient experience to obtain accurate values, this is no longer necessary. Furthermore, since an origin is established for each indexed tool mounting unit 211 in this embodiment, even if there is a dimensional error in the turret tool post 21, coordinate values ​​based on the appropriate origin can be set for each indexed turret tool T.

[0034] Although one embodiment of the present invention has been described, the present invention is not limited to this, and various modifications are possible within the scope of the present invention. For example, although the machine tool 1 in the above embodiment has been described using an opposed two-spindle lathe as an example, the present invention is not limited to this type of machine tool. In the above embodiment, the correction value is obtained by centering the touch probe 51 and the origin establishment master 53, but the correction value may be obtained in advance by measuring the tool post 21.

[0035] REFERENCE SIGNS LIST 1 machine tool 3 first workpiece spindle device 4 second workpiece spindle device 5 turret device 8 control device 12, 16 spindle chuck 21 turret tool rest 48 receiver 51 touch probe 53 origin establishment master 211 tool mounting section 511 stylus 531 measuring section

Claims

a turret device which has a turret tool post to which a plurality of turret tools can be attached and detached and which can be indexed by rotating about an axis of rotation parallel to the spindle of the work spindle device, and which positions the indexed turret tools during machining by moving in a predetermined direction; a control device which controls the drive of the work spindle device and the turret device; and an origin establishment master having a circular hole formed as a measuring portion, which is fixed to the tool mounting portion of the turret tool post to which the turret tools are attached, and a wireless touch probe is held by the spindle chuck, so that the stylus of the touch probe is brought into contact with the inner surface of the relatively inserted measuring portion by driving the turret device, and the central coordinates of the measuring portion are established as the origin in the control device based on a trigger signal transmitted from the touch probe.

2. A machine tool as described in claim 1, wherein the origin establishment master is fixed to all tool mounting portions of the turret tool rest, and origin establishment is performed in accordance with the automatic origin establishment system by an indexed, specific origin establishment master.

3. A machine tool as described in claim 1 or claim 2, wherein the automatic origin establishment system uses the coordinate value obtained by the first origin establishment master among the origin establishment masters fixed to all tool mounting parts of the turret tool post as an origin reference value, and records as a correction value the amount of deviation of the coordinate value from the origin reference value for the origin obtained by the second or subsequent origin establishment masters.

4. The machine tool of claim 1, wherein the work spindle device comprises a first work spindle device and a second work spindle device arranged opposite each other with their respective spindles coaxially, the turret device is capable of machining workpieces held in the spindle chucks of the first work spindle device and the second work spindle device by a turret tool mounted on the turret tool rest, and the automatic origin establishment system establishes the origin of the turret device by a wireless touch probe held in each spindle chuck of the first work spindle device and the second work spindle device.

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