JP2013244551A - Tool mounting state detection device in machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact and versatile tool mounting state detection device in a machine tool.SOLUTION: In a machine tool having a drawbar 6 for clamping or unclamping a tool to/from a front end of a main shaft 5 extending in a front-back direction, a tool mounting state detection device in a machine tool detects a clamped state where a tool is clamped to a main shaft or an unclamped state where the tool is unclamped from the main shaft, or a tool unmounted state where the tool is not mounted on the main shaft. The tool mounting state detection device includes: a position detector 7 which is fixed to the drawbar, comprises magnetic metal, and moves in a front-back direction; a sensor 8 which has an exciting coil 37 for generating eddy current in the position detector and detects electrical characteristics of the exciting coil to be varied by eddy current when the position detector crosses; and a determination means which determines, based on electrical characteristics detected by the sensor, whether the tool is in the clamped state, the unclamped state, the tool unmounted state, or an undefined state.

Description

  According to the present invention, in a machine tool having a draw bar that operates to clamp or unclamp a tool at the front end of a spindle, the tool is clamped or unclamped, or the tool is placed in the draw bar by detecting the position of the draw bar. The present invention relates to a tool attachment state detection device in a machine tool that detects an unattached state.

  For example, Patent Document 1 discloses a drawbar position detector that is attached to a spindle unit of a machining center and detects the position of a drawbar that moves in the axial direction of a spindle shaft and operates to clamp or unclamp a tool. ing. In this draw bar position detector, a hollow cylindrical coil is disposed around a core made of a magnetic material and formed integrally with the draw bar, the draw bar moves in the axial direction, and the position of the core relative to the coil is determined. When the inductance value of the coil changes due to the change, the LC transmitter connected to the coil generates a frequency signal according to the inductance value.

  In addition, the tool is clamped (clamped) or unclamped (unclamped) by the drawbar operation, or the tool is not attached to the spindle unit by the drawbar operation (tool not installed) At this time, the counter value of the frequency signal in each state is stored in the memory in advance, and the counter value stored in the memory is used as the current counter value of the frequency signal generated by the LC transmitter during the operation of the draw bar. Based on the comparison result, it is possible to detect which state is the clamped state, the unclamped state, or the tool non-attached state.

Special table 2007-500084

  However, in the draw bar position detector described above, the sensor required for detecting the clamp state and the like is a hollow cylindrical coil disposed around a core formed integrally with the draw bar. There was an inconvenience that the sensor was enlarged. Therefore, there has been a demand for downsizing the sensor that detects the clamped state and the like.

  Furthermore, when the above-described coil is used as a sensor, since the sensor must be individually manufactured in accordance with the shape of the draw bar included in each machining center, there is a concern that the versatility of the sensor is inferior.

  The present invention has been proposed in view of such a situation, and is a machine that can be downsized and has excellent versatility, and can accurately detect a clamped state or an unclamped state of a tool, or an unattached state of a tool. An object of the present invention is to provide a tool attachment state detection device in a machine.

  A tool attachment state detecting device in a machine tool according to the invention of claim 1 extends in the front-rear direction so that a plurality of different tools can be exchangeably attached to the front end, and is movable in the front-rear direction inside the main spindle. In a machine tool that is disposed and has a draw bar that clamps or unclamps the tool at the front end of the main shaft by movement in the front-rear direction, by detecting the position of the draw bar in the front-rear direction, It is possible to detect a clamped state in which the tool is clamped on the spindle, an unclamped state in which the tool is unclamped on the spindle, and a tool unattached state in which the tool is not attached to the spindle. A tool attachment state detection device in a machine tool, comprising a metal having magnetism fixed to the draw bar, A position detector that moves in the front-rear direction by moving the bar in the front-rear direction, and a position detector that crosses the position detector in the front-rear direction, and a current is supplied to the position detector, A single sensor having an exciting coil for generating an electric current, and detecting an electric characteristic of the exciting coil that is changed by the eddy current as the position detector crosses; and the electric characteristic detected by the sensor On the basis of the clamped state, the unclamped state, the tool unattached state, or the undefined state that is different from any of the clamped state, the unclamped state, and the tool unattached state. Determining means for determining whether or not.

  According to a second aspect of the present invention, in the first aspect, the electrical characteristics detected by the sensor in each of the clamped state, the unclamped state, and the tool unattached state for each of the plurality of different tools in advance. Collecting means that collects characteristic data corresponding to the tool, storage means that stores the characteristic data collected by the collecting means in each state in association with each tool as reference data, and the attached to the spindle Selecting means for selecting the reference data in each state stored in the storage means in association with the specific tool included in a plurality of different tools, and the determination means is selected by the selection means The reference data in each state and the respective states of the specific tool detected by the sensor. Kicking on the basis of the characteristic data and the comparison result of comparing, and judging whether said is any or the undefined of the respective states.

  According to a third aspect of the present invention, in the second aspect, the determination unit calculates a variation in the characteristic data in each state with respect to the reference data in each state based on the comparison result, and stores the variation in the characteristic data in the storage unit. And updating means for updating the reference data in each of the states thus obtained to the corrected reference data in which the variation calculated by the determination means is reduced.

  According to a fourth aspect of the present invention, there is provided the programmable logic controller according to the second or third aspect, wherein the programmable logic controller controls the operation of the machine tool according to a predetermined control command, and the programmable logic controller communicates with the determination means by I / O communication. Then, the processing request command is transmitted and the characteristic data in each state is received.

According to the tool attachment state detection apparatus for a machine tool according to the first aspect of the present invention, it is not necessary to dispose the sensor around the draw bar, and the position detection body fixed to the draw bar and moving in the front-rear direction of the spindle traverses. Therefore, the sensor can be miniaturized.
In addition, a sensor can be shared for a machine tool in which a position detector is fixed to a draw bar. Therefore, the sensor has excellent versatility.
According to the invention of claim 2, the determining means is that the specific tool attached to the spindle from among a plurality of different tools is in a clamped state, an unclamped state, a tool unattached state, or an undefined state. Can be determined automatically. Therefore, it is possible to accurately and easily determine each state of the specific tool (clamped state, unclamped state, tool unattached state) and undefined state.
According to the third aspect of the present invention, it is possible to automatically reduce the variation in the characteristic data with respect to the reference data in each state for each specific type of tool attached to the spindle from among a plurality of different tools. Therefore, the determination means in each state can compare the correction reference data and the characteristic data with reduced variations, so that the determination accuracy of each state of the specific tool can be improved.
According to the invention of claim 4, a communication interface is provided between the programmable logic controller and the determination means in order to send and receive processing request commands and characteristic data in each state between the programmable logic controller and the determination means. There is no need to provide a new one. Therefore, the manufacturing cost of the tool attachment state detection device can be reduced.

It is a front view of a machining center provided with a tool attachment state detecting device of an embodiment of the present invention. It is a side view of the machining center. It is an enlarged view of the A part of FIG. FIG. 4 is a view on arrow YY in FIG. 3. It is an enlarged view of the B part of FIG. FIG. 5 is an enlarged view of a portion C in FIG. 4. It is the figure which showed the state by which the tool was unclamped to the main axis | shaft. It is the figure which showed arrangement | positioning of the sensor and position detection body in the state by which the tool was unclamped to the main axis | shaft. It is the figure which showed the state in which the tool is not attached to the main axis | shaft. It is the figure which showed arrangement | positioning of the sensor and position detection body in the state in which the tool is not attached to the main axis | shaft. It is a schematic block diagram of the tool attachment state detection apparatus. It is a flowchart regarding the reference | standard data accumulation | storage process which the microcomputer which comprises the tool attachment state detection apparatus performs. It is a flowchart regarding the tool attachment state detection process which the microcomputer performs.

  An embodiment of the present invention will be described with reference to FIGS. A horizontal machining center 1 shown in FIGS. 1 to 10 includes a base 2, a column 3, a main spindle device 4, a main spindle 5, a draw bar 6, a position detector 7, a sensor 8, a tool magazine 9, A work placement table 10, an operation panel 11, and a control panel 12 are provided. The machining center 1 is an example of the machine tool of the present invention.

  As shown in FIGS. 1 and 2, a cover 15 is disposed on the base 2, and the front side and the rear side of the base 2 and the left and right side surfaces of the base 2 are surrounded by the cover 15. Yes. A column 3 is erected on the upper surface of the base 2. In the column 3, a spindle device 4 is provided so as to be movable in the front-rear direction (left-right direction in FIG. 2). In this embodiment, as shown in FIGS. 3 and 4, two guide rails 16, 16 extending in the front-rear direction are fitted on the outer surface of the spindle device 4, and each guide rail 16 is slidably fitted in the column 3. A full guide block 17 is provided. The spindle device 4 can be moved in the longitudinal direction by feeding the spindle device 4 in the longitudinal direction and sliding the guide rails 16 of the spindle device 4 along the guide blocks 17. Further, the spindle device 4 is movable in the vertical direction.

  As shown in FIG. 4, in the spindle device 4, the spindle 5 extends in the front-rear direction (left-right direction in FIG. 4) and is rotatably supported by a plurality of bearings 19 provided in the spindle head 18. The main shaft 5 is rotationally driven by a main shaft motor M provided at the rear portion of the main shaft device 4. A mounting hole 21 (see FIGS. 3 and 5) in which various tools 20 (see FIGS. 2 and 5) and the like held in the tool magazine 9 can be mounted is formed in the distal end surface of the main shaft 5. . In addition, illustration of the tool 20 was abbreviate | omitted in FIG. Further, as shown in FIG. 4, a through hole 22 that penetrates the shaft center is formed inside the main shaft 5. A draw bar 6 (see FIGS. 4 and 5) is inserted into the through hole 22 so as to be movable in the front-rear direction. A plurality of disc springs 23 (see FIG. 4) are stacked between the inner peripheral surface of the through hole 22 and the outer peripheral surface of the draw bar 6. The draw bar 6 is formed with a cutting oil supply passage 24 (see FIGS. 4 and 5) that penetrates the shaft center.

  Further, as shown in FIGS. 4 and 6, on the rear side (right side in FIG. 4) of the draw bar 6, pin members 25 having both ends projecting outward from the outer peripheral surface of the main shaft 5 are perpendicular to the axial center direction of the draw bar 6. It is being fixed in the state which penetrated the draw bar 6 in the direction to do. As shown in FIG. 6, an annular fixing member 26 is fitted on the outer peripheral surface of the main shaft 5. The fixing member 26 includes a through hole 27 that penetrates in the vertical direction and can be inserted into both ends of the pin member 25. In addition, an annular and iron position detector 7 is fixed to the outer peripheral surface of the fixing member 26 in a state where it is screwed to a pin member 25 facing from each through hole 27. Since the position detector 7 is made of iron, it can be magnetized.

  As shown in FIGS. 4 and 6, the main spindle device 4 accommodates a cylinder 28 so as to be coaxial with the central axis of the main spindle 5. Further, the cylinder 28 accommodates a piston 29 that is coaxial with the central axis of the main shaft 5 and is slidably fitted on the outer surface of the main shaft 5. As shown in FIGS. 6 and 8, the piston 29 pushes the fixing member 26 forward when the hydraulic oil is supplied to the push side from the hydraulic device and advances in the axial direction along the outer surface of the main shaft 5. Become. Accordingly, the position detector 7 fixed to the fixing member 26 and the draw bar 6 connected to the position detector 7 via the pin member 25 move forward.

  As shown in FIGS. 4, 5 and 9, a tool insertion hole 31 is formed at the tip of the draw bar 6. The tool mounting hole 31 is opened at the distal end surface of the draw bar 6 and communicates with the cutting oil supply path 24 and is larger in diameter than the cutting oil supply path 24. Furthermore, an annular engagement protrusion 32 is provided at the front end of the draw bar 6 so as to protrude toward the outside of the draw bar 6. FIG. 5 shows a state in which the tool 20 is clamped to the front end of the main shaft 5 by the operation of the draw bar 6. As shown in FIGS. 2 and 5, the tool 20 is a cylindrical body that extends in the front-rear direction of the spindle device 4, has a drill attached to the front surface, and has a rear surface opened. Is projected toward the inside of the tool 20. In addition, a cylindrical portion 34 that extends along the axial direction and can be inserted into the tool mounting hole 31 (see FIGS. 5 and 9) is provided inside the tool 20. An inflow passage 36 (see FIG. 5) for cutting oil is formed in the cylindrical portion 34 in the axial direction. In the state shown in FIG. 5, after the cylindrical portion 34 is inserted into the tool mounting hole 31, the engagement protrusion 32 and the engagement claw portion 33 are engaged, and the disc spring 23 (see FIG. 4). The draw bar 6 is urged toward the rear side of the main shaft 5 by the urging force. As a result, the engaging claw 33 is pulled into the mounting hole 21 by the engaging protrusion 32, so that the tool 20 is clamped to the front end of the main shaft 5 by the operation of the draw bar 6.

  As shown in FIG. 4 and FIG. 6, one sensor 8 is arranged above the position detection body 7 and close to the position detection body 7. Here, the lower surface of the sensor 8 is a flat detection surface, and the gap between the detection surface and the surface of the position detector 7 is set to about 0.5 mm. The sensor 8 incorporates an exciting coil 37. When an excitation current (high-frequency current) is passed through the excitation coil 37 to generate a high-frequency magnetic field, an eddy current flows through the position detector 7 due to the high-frequency magnetic field. In the present embodiment, as will be described later, the tool 20 is operated by the operation of the draw bar 6 by utilizing the fact that the amplitude of the signal detected by the sensor 8 changes due to the eddy current flowing through the position detector 7 that moves with the draw bar 6. Is clamped to the front end of the main shaft 5 (clamped state), the tool 20 is unclamped to the front end by the operation of the draw bar 6 (unclamped state), and the tool 20 is attached to the front end by the operation of the draw bar 6 It is determined which state is not in the state (tool is not attached). Therefore, by detecting the difference in position of the position detector 7 from the amplitude of the signal detected by the sensor 8, the difference in position can be accurately detected. Along with this, it is possible to precisely determine whether the state is any of the above states.

  As shown in FIGS. 1 and 2, the tool magazine 9 is disposed above the spindle device 4. The tool magazine 9 includes a disk-shaped tool holding plate 38 and a drive motor 39 that rotationally drives the tool holding plate 38. As shown in FIG. 1, a plurality of holding portions 40 each holding various tools 20 </ b> A (see FIG. 2) including the tool 20 detachably are formed on the outer periphery of the tool holding plate 38. As shown in FIGS. 1 and 2, a work placement table 10 is disposed at a machining position of the machining center 1 in the cover 15. Various workpieces to be drilled with a tool 20 clamped to the front end of the main shaft 5 by the operation of the draw bar 6 can be detachably fixed to the upper surface of the workpiece mounting table 10, for example. In addition, an operation panel 11 is fixed to the base 2.

  As shown in FIG. 2, the control panel 12 is erected on the rear side of the spindle device 4 and fixed to the rear portion of the base 2. The control panel 12 accommodates a control device 42 shown in FIG. 11 and a programmable logic controller 43 (hereinafter referred to as “PLC 43”) shown in FIG. In addition, the sensor 8, the control apparatus 42, PLC43, and the oscillator 51 which are shown in FIG. 11 are examples of the tool attachment state detection apparatus of this invention.

  As shown in FIG. 11, the control device 42 includes a reception signal adjustment unit 44, a microcomputer 45, an offset adjustment unit 46, a storage unit 47, a reception port 48, and a transmission port 49. The above-described sensor 8 is connected to the reception signal adjustment unit 44. An oscillator 51 that supplies an excitation current to the excitation coil 37 of the sensor 8 is connected to the sensor 8. The sensor 8 detects the voltage between both ends of the exciting coil 37 that fluctuates due to a change in impedance of the exciting coil 37 based on the eddy current flowing through the position detector 7 that moves together with the draw bar 6. The reception signal adjustment unit 44 receives a detection signal corresponding to the amplitude of the both-end voltage detected by the sensor 8. The voltage across the excitation coil 37 is an example of the electrical characteristics of the excitation coil of the present invention.

  A reception signal adjustment unit 44 and an offset adjustment unit 46 are connected to the microcomputer 45. When the microcomputer 45 detects that the amplitude of the detection signal received from the sensor 8 is larger than the upper limit of the readable amplitude limit value, the microcomputer 45 transmits an offset subtraction command signal to the offset adjustment unit 46. On the other hand, when the microcomputer 45 detects that the amplitude is smaller than the lower limit of the amplitude limit value, the microcomputer 45 transmits an offset addition command signal to the offset adjustment unit 46. When the offset adjustment unit 46 receives the offset subtraction command signal, the offset adjustment unit 46 transmits an offset subtraction processing signal to the reception signal adjustment unit 44. On the other hand, when receiving the offset addition command signal, the offset adjustment unit 46 transmits an offset addition processing signal to the reception signal adjustment unit 44.

  When receiving the offset subtraction command signal, the reception signal adjustment unit 44 generates an offset subtraction signal by subtracting the level of the offset signal from the amplitude of the detection signal of the sensor 8. This offset subtraction signal is transmitted to the microcomputer 45. On the other hand, when receiving the offset addition command signal, the reception signal adjustment unit 44 adds the level of the offset signal to the amplitude of the detection signal of the sensor 8 to generate an offset addition signal. This offset addition signal is transmitted to the microcomputer 45.

  Furthermore, a storage unit 47 is connected to the microcomputer 45. When the microcomputer 45 detects that the amplitude of the detection signal of the sensor 8 is less than or equal to the upper limit of the amplitude limit value and greater than or equal to the lower limit, the amplitude data of the detection signal is stored in the storage unit 47 by the operation of the draw bar 6. It is stored in association with the model data of the tool 20 clamped at the front end of the main shaft 5. On the other hand, when the microcomputer 45 detects that the amplitude is larger than the upper limit of the amplitude limit value, the amplitude data of the offset subtraction signal is stored in the storage unit 47 in association with the model data. Further, when the microcomputer 45 detects that the amplitude is smaller than the lower limit of the amplitude limit value, the amplitude data of the offset addition signal is stored in the storage unit 47 in association with the model data.

  In addition, a reception port 48 and a transmission port 49 are connected to the microcomputer 45. The reception port 48 and the transmission port 49 are connected to the PLC 43. The reception port 48 and the transmission port 49 are provided to match the level of signals transmitted and received between the microcomputer 45 and the PLC 43. The PLC 43 is used to perform monitoring and operation control of the machining center 1. The microcomputer 45 can receive communication data having a processing request command for requesting data transmission from the PLC 43 via the reception port 48 by performing I / O communication with the PLC 43 at a predetermined timing. Yes. When the microcomputer 45 receives the communication data processing request command by the I / O communication, the microcomputer 45 sends amplitude data of each state (an unclamped state, a clamped state, and a tool non-attached state) described later via the transmission port 49. Transmission to the PLC 43 is enabled.

  As shown in FIG. 11, the operation panel 11 is connected to the microcomputer 45. The operation panel 11 is provided with various buttons and a touch panel that can be operated by an operator of the machining center 1. For example, the operator inputs the model data of the tool 20 to be clamped to the front end of the main shaft 5 by the operation of the draw bar 6 from among a plurality of different tools 20 and 20A by operating the buttons and the like.

  In addition, an external input / output interface 52 is connected to the microcomputer 45. A personal computer 53 is connected to the external input / output interface 52. When the operator operates the keyboard of the personal computer 53, the personal computer 53 sends a test signal based on the test data stored in the storage device of the personal computer 53 to the microcomputer 45 via the external input / output interface 52. Send. As a result, the personal computer 53 causes the microcomputer 45 to perform a test operation.

  In this embodiment, as will be described below with reference to FIG. 12, the microcomputer 45 applies excitation to the storage unit 47 of the control device 42 based on the data collection control program stored in the storage device of the microcomputer 45. A process of storing amplitude data corresponding to the amplitude of the voltage across the coil 37 as reference data is executed. When the operator operates the operation panel 11 before machining the workpiece and selects the learning mode, a plurality of different tools that can clamp the amplitude data in advance to the front end of the spindle 5 by the operation of the draw bar 6 before machining the workpiece. Can be stored in the storage unit 47 in association with each other. In particular, in the present embodiment, the amplitude data in each of the clamped state, the unclamped state, and the tool non-attached state can be stored in the storage unit 47 in association with the tool 20 or the like.

  In the learning mode, when the operator operates the operation panel 11 and inputs the model data of the tool 20, the microcomputer 45 stores the model data in the storage unit 47.

  In the learning mode, the microcomputer 45 performs unclamped reference data collection / storage processing (S11) and tool non-attachment reference data collection / storage processing (S12) as reference data storage processing (S10) as shown in FIG. And clamping reference data collection / storage processing (S13).

  In the unclamped reference data collection / storage process (S11), the microcomputer 45 receives the amplitude data in the unclamped state from the reception signal adjustment unit 44, and the type of the tool 20 input by the operator on the operation panel 11 A process of storing in the storage unit 47 in association with the data is executed. The PLC 43 moves the spindle device 4 up and down or back and forth according to a predetermined control command in the machining control program stored in the storage device of the PLC 43, so that the tool 20 corresponding to the model is moved from the holding unit 40 of the tool magazine 9. The control of detaching and mounting in the mounting hole 21 of the spindle 5 as shown in FIG. 7 is executed over a first predetermined time. At the same time, the PLC 43 moves the draw bar 6 forward by pushing the fixing member 26 forward (left side in FIG. 8) with the piston 29 as shown in FIG. The control for setting the unclamped state in which the engagement is released is executed over a first predetermined time. Then, with the detection surface of the sensor 8 facing the surface of the position detector 7 as shown in FIG. 8, the microcomputer 45 receives the amplitude data by the unclamped reference data collection / storage process (S11). The amplitude data received from the signal adjustment unit 44 is stored in the storage unit 47 in association with the model data of the tool 20 as reference data in the unclamped state. The microcomputer 45 is an example of the collecting means of the present invention, and the storage unit 47 is an example of the storing means of the present invention. Amplitude data is an example of characteristic data of the present invention.

  After the unclamping reference data collection / storage process (S11), the microcomputer 45 executes the reference data collection / storage process (S12) when the tool is not attached. In the tool non-attachment reference data collection / storage process (S12), the microcomputer 45 receives the amplitude data in the tool non-attachment state from the reception signal adjustment unit 44, and the unclamping reference data collection / storage process (S11). ) To store the data in the storage unit 47 in association with the model data of the tool 20 used in the above. The PLC 43 moves the spindle device 4 up and down or moves back and forth after the first predetermined time elapses according to a predetermined control command, so that the tool 20 mounted in the mounting hole 21 is held by the holding portion 40 of the tool magazine 9. To grip. Following this, the spindle device 4 is returned to the position before the movement, and the control for putting the tool 20 in the mounting hole 21 without mounting the tool 20 as shown in FIG. 9 is executed for a second predetermined time. At the same time, the PLC 43 causes the position detector 7 to horizontally traverse the lower side of the sensor 8 to the rear side of the main shaft 5 (right side in FIG. 10) by the biasing force of the disc spring 23 (see FIG. 4). As shown, the control for urging the draw bar 6 to the rear side is executed for a second predetermined time. As shown in FIG. 10, the microcomputer 45 is in a state where the overlap area between the detection surface of the sensor 8 and the surface of the position detection body 7 is smaller than the unclamped state shown in FIG. By the reference data collection / storage process (S12), the amplitude data received from the reception signal adjustment unit 44 is stored in the storage unit 47 in association with the model data of the tool 20 as reference data in the tool unattached state. As shown in FIG. 10, the impedance of the excitation coil 37 is changed by reducing the overlap area. As a result, the amplitude of the detection signal of the sensor 8 in the tool unattached state is larger than the amplitude in the unclamped state. .

  After the tool non-attachment reference data collection / storage process (S12), the microcomputer 45 executes the clamping reference data collection / storage process (S13). In the clamping reference data collection / storage process (S13), the microcomputer 45 receives the amplitude data in the clamped state from the reception signal adjustment unit 44, and the model data of the tool 20 used in each process (S11, S12). A process of storing in the storage unit 47 in association with the above is executed. The PLC 43 mounts the tool 20 corresponding to the model again in the mounting hole 21 as shown in FIG. 5 by moving the spindle device 4 up and down or back and forth after the second predetermined time has elapsed according to a predetermined control command. The control to perform is performed over a third predetermined time. At the same time, the PLC 43 causes the position detecting body 7 to horizontally traverse the lower side of the sensor 8 to the rear side (right side in FIG. 6) of the main shaft 5 by the urging force of the disc spring 23, and as shown in FIG. Thus, the engagement claw portion 33 is pulled into the mounting hole 21 so that the control to make the clamp state is executed for a third predetermined time. As shown in FIG. 6, the overlap area between the detection surface of the sensor 8 and the surface of the position detector 7 is larger than that in the tool unattached state shown in FIG. 10, and the unclamped state shown in FIG. 8. In a state where the overlap area is further reduced, the microcomputer 45 uses the amplitude data received from the received signal adjustment unit 44 by the clamping reference data collection / storage process (S13) as reference data in the clamped state. Are stored in the storage unit 47 in association with the model data. The amplitude of the detection signal of the sensor 8 in the clamped state is smaller than the amplitude in the tool non-attached state and larger than the amplitude in the unclamped state.

  By executing each process (S11 to S13) by the number of tools held in the tool magazine 9 by the reference data accumulation process (S10), the reference in each state of the clamped state, the unclamped state, and the tool unattached state The data can be stored in the storage unit 47 in association with the model data of all the tools held in the tool magazine 9. When the operator operates the operation panel 11 to cancel the learning mode, the reference data accumulation process (S10) ends.

  Next, the operation of the machining center 1 will be described with reference to FIG. In the present embodiment, when the operator operates the operation panel 11 to select the normal mode and inputs the model data of the tool 20 used for machining the workpiece, the microcomputer 45 moves the spindle 5 before machining the workpiece. The process which detects the attachment state of the said tool 20 with respect to is performed. The microcomputer 45 executes a tool attachment state detection process (S20) as shown in FIG. 13 based on a tool attachment state detection control program stored in the storage device of the microcomputer 45, for example, every 2 msec. In the tool attachment state detection process (S20), the characteristic data collection process at the time of unclamping (S22), the characteristic data collection process at the time of no tool attachment (S23), the characteristic data collection process at the time of clamping (S24), and the reference data selection Processing (S25), tool attachment state determination processing (S26), determination of whether the numerical value of the amplitude data is within the allowable range (S27), reference data update processing (S28), and determination data transmission processing ( S29) is executed.

  The microcomputer 45 first executes unclamped characteristic data collection processing (S22). In the unclamped characteristic data collection process (S22), the process of receiving the amplitude data in the unclamped state from the reception signal adjustment unit 44 by the same method as the unclamped reference data collection / storage process (S11) described above. Run.

  After the unclamping characteristic data collection process (S22), the microcomputer 45 executes the tool non-attachment characteristic data collection process (S23). In the tool non-attachment characteristic data collection process (S23), amplitude data in the tool non-attachment state is received from the reception signal adjustment unit 44 in the same manner as the tool non-attachment reference data collection / storage process (S12) described above. Execute the process.

  After the tool non-attachment characteristic data collection process (S23), the microcomputer 45 executes the clamping characteristic data collection process (S24). In the clamping characteristic data collection process (S24), a process of receiving the amplitude data in the clamped state from the reception signal adjustment unit 44 is executed in the same manner as the clamping reference data collection / storage process (S13).

  After the clamping characteristic data collection process (S24), the microcomputer 45 executes a reference data selection process (S25). In the reference data selection process (S25), the model data of the tool 20 input by the operator on the operation panel 11 is selected from the reference data in each state stored in the storage unit 47 by the above-described processes (S11 to S13). A process of selecting reference data in each associated state is executed. The microcomputer 45 is an example of the selection unit of the present invention, and the tool 20 attached to the main shaft 5 from among a plurality of different tools 20, 20A, etc. is an example of a specific tool of the present invention.

  After the reference data selection process (S25), the microcomputer 45 executes a tool attachment state determination process (S26). In the tool attachment state determination process (S26), whether or not the reference data in each state selected by the reference data selection process (S25) matches the amplitude data in each state received by each process (S22 to S24). Is determined. Thereby, it is determined whether the machining center 1 is in a clamped state, an unclamped state, a tool unattached state, an undefined state different from any of the clamped state, the unclamped state, and the tool unattached state. Here, the numerical value of the amplitude data in each state (clamped state, unclamped state, tool non-attached state) is the allowable upper limit value and allowable lower limit value of the reference data in each state determined taking into account the detection error of the sensor 8, for example. It is determined whether the value is within a range (within an allowable range). As a result of executing the tool attachment state determination process (S26), if the amplitude data is within the allowable range of the reference data in the clamped state, it is determined that the machining center 1 is in the clamped state. If the amplitude data is within the allowable range of the reference data in the unclamped state, the unclamped state is indicated. If the amplitude data is within the allowable range of the reference data in the tool not attached state, the tool is not attached. Judge each one. On the other hand, if the amplitude data is not within the allowable range of the reference data in each state (clamped state, unclamped state, tool unattached state), it is determined that the state is undefined. In addition to this, in the tool attachment state determination process (S26), the amount of variation corresponding to the deviation of the numerical value of the amplitude data with respect to the numerical value of the reference data in each state (clamped state, unclamped state, tool unattached state) is calculated. . The microcomputer 45 is an example of a determination unit of the present invention.

  After the tool attachment state determination process (S26), the microcomputer 45 determines whether or not the numerical value of the amplitude data in each state is within an allowable range (S27). In S27, when it is determined that the numerical value of the amplitude data is within the allowable range and each state is normal, the microcomputer 45 executes the reference data update process (S28). In the reference data update process (S28), a process is executed in which the reference data in each state stored in the storage unit 47 is updated to corrected reference data in which the variation amount calculated in the tool attachment state determination process (S26) is reduced. To do. Here, the numerical value of the correction reference data is obtained by adding the numerical value of half the variation amount to the numerical value of the reference data. By executing the reference data update process (S28), the reference data can be corrected so as to reduce the variation amount of the amplitude data with respect to the reference data of the tool 20 or the like attached to the spindle 5 each time the workpiece is processed. It becomes possible. When machining the next workpiece with the tool 20, it is determined in the tool attachment state determination process (S26) whether the amplitude data is within the allowable range of the correction reference data updated by the reference data update process (S28). Is done. The microcomputer 45 is an example of the updating unit of the present invention.

  After the reference data update process (S28), the microcomputer 45 executes a determination data transmission process (S29). In the determination data transmission process (S29), communication data having data (normal determination data) determined that the numerical value of the amplitude data in each state is within the allowable range is sent to the PLC 43 via the transmission port 49 by I / O communication. Execute the process to send.

  On the other hand, in S27, if it is determined that any of the states (unclamped state, clamped state, tool unattached state) is not within the allowable range and is in an undefined state, the microcomputer 45 determines the determination data. In the transmission process (S29), a process of transmitting communication data having data determined to be in an undefined state (undefined state determination data) to the PLC 43 by I / O communication is executed.

  Further, in the normal mode, the PLC 43 performs I / O communication on communication data having normal determination data transmitted by the determination data transmission process (S29) executed by the microcomputer 45 and communication data having undefined state determination data. The processing to be received by each is executed. When the PLC 43 determines that the communication data having the undefined state determination data has been received for the fourth predetermined time, the PLC 43 executes the abnormality notification process. In this abnormality notification process, a process of notifying the operator that it has been determined that the state is undefined is executed. Here, the LED lamp which notifies the undefined state provided in the alarm display part of the operation panel 11 was made to light. When determining that the PLC 43 is in an undefined state, the PLC 43 executes processing for stopping the operation of the machining center 1.

  In addition, when determining that the PLC 43 is in an undefined state, the PLC 43 transmits communication data having a processing request command to the microcomputer 45 via the reception port 48 (see FIG. 11) by I / O communication. When the microcomputer 45 receives the communication data having the processing request command from the PLC 43, the microcomputer 45 sends each state (unclamped state, clamped state, and the like) to the PLC 43 via the transmission port 49 (see FIG. 11). The amplitude data of the tool unattached state is transmitted. The operator predicts the cause determined to be in the undefined state based on the numerical value of the amplitude data of each state. As an example of the cause, when the tool 20 is clamped to the front end of the main shaft 5 by the operation of the draw bar 6, workpiece cutting waste is caught between the tool 20 and the mounting hole 21 of the main shaft 5. It is done. In addition, as an example of the cause, there are fluctuations in the signal level due to wear and temperature drift caused by the forward / backward movement of the draw bar 6.

<Effect of this embodiment>
In the machining center 1 of this embodiment, it is not necessary to arrange the sensor 8 around the draw bar 6 in order to detect the mounting state of the tool 20 with respect to the main shaft 5, and the sensor 8 is fixed to the draw bar 6 via the pin member 25. Then, it is only necessary to provide one position detector 7 that crosses the main shaft 5 and moves in the front-rear direction. Therefore, the sensor 8 can be downsized.
In addition, the sensor 8 can be shared with a machining center in which the position detector 7 is fixed to the draw bar 6. Therefore, the sensor 8 has excellent versatility.

  Further, the microcomputer 45 executes the tool attachment state determination process (S26), and the amplitude data in each state (clamped state, tool unattached state, unclamped state) is selected by the reference data selection process (S25). By determining that it is within the allowable range of the reference data in each state (clamped state, tool unattached state, unclamped state), the tool 20 attached to the spindle 5 from among a plurality of different tools 20, 20A, etc. Each state (clamped state, tool unmounted state, unclamped state) can be automatically identified. In addition, the microcomputer 45 executes a tool attachment state determination process (S26), and the amplitude data in each state is within the allowable range of the reference data in each state selected by the reference data selection process (S25). By determining that there is no, it can be automatically determined that the state is undefined. Therefore, it is possible to accurately and easily determine each state of the tool 20 (clamped state, tool unattached state, unclamped state) and undefined state.

  Furthermore, the microcomputer 45 executes the reference data update process (S28), and the amount of variation in the amplitude data with respect to the reference data of the tool 20 attached to the spindle 5 is reduced in the reference data in each state stored in the storage means 47. The data was updated to correction reference data corrected as described above. For this reason, the amount of variation can be automatically reduced. Therefore, the microcomputer 45 can determine whether or not the amplitude data is within the allowable range of the correction reference data in which the variation amount is reduced in each state, so that the determination accuracy of each state of the tool 20 can be determined. Can be improved.

  In addition, in order to transmit / receive communication data having a processing request command, communication data having normal determination data, and communication data having undefined state determination data between the PLC 43 and the microcomputer 45 by I / O communication. It is not necessary to newly provide a communication interface between the PLC 43 and the microcomputer 45 in order to transmit / receive each communication data. Therefore, the cost for constructing an apparatus for detecting the attachment state of the tool 20 to the spindle 5 can be reduced.

  The present invention is not limited to the above-described embodiment, and can be implemented by appropriately changing a part of the configuration without departing from the spirit of the invention. For example, unlike the above-described embodiment, the microcomputer 45 determines whether the amplitude data in each state matches the reference data (correction reference data), so that the machining center 1 is in each state (clamped state, unclamped). State, tool unattached state) or undefined state.

  1 .. Machining center, 5 .. Spindle, 6 .. Drawbar, 7 .. Position detector, 8 .. Sensor, 20 .. Tool, 37 .. Excitation coil, 42 .. Control device, 45. 43..Programmable logic controller 47..Storage unit of control device 51..Oscillator.

Claims (4)

A main shaft that extends in the front-rear direction and has a plurality of different tools attached to the front end in a replaceable manner, and is disposed inside the main shaft so as to be movable in the front-rear direction. A draw bar that clamps or unclamps the tool, and detecting the position of the draw bar in the front-rear direction, the clamp state in which the tool is clamped to the spindle, and the spindle to the spindle A tool attachment state detection device in a machine tool capable of detecting an unclamped state where a tool is unclamped and a tool unattached state where the tool is not attached to the spindle,
A position detector that is made of a metal having magnetism fixed to the draw bar, and moves in the front-rear direction by moving the draw bar in the front-rear direction;
The position detection body is arranged so as to cross in the front-rear direction, and has an exciting coil that generates an eddy current in the position detection body when current is supplied, and the position detection body crosses the eddy current. A single sensor for detecting the electrical characteristics of the exciting coil, which varies according to
Based on the electrical characteristics detected by the sensor, the clamped state, the unclamped state, the tool unattached state, or the clamped state, the unclamped state, and the tool unattached state are not yet different. A determination means for determining which of the defined states is;
A tool attachment state detection device for a machine tool, comprising: Collecting means for collecting characteristic data corresponding to the electrical characteristics detected by the sensor in each state of the clamped state, the unclamped state, or the tool unattached state for each of the plurality of different tools in advance.
Storage means for storing, as reference data, the characteristic data collected by the collecting means in each state in association with each of the tools;
Selecting means for selecting the reference data in each state stored in the storage means in association with the specific tool included in the plurality of different tools attached to the spindle;
The determination unit is based on a comparison result obtained by comparing the reference data in each state selected by the selection unit and the characteristic data in each state of the specific tool detected by the sensor. The tool attachment state detection device for a machine tool according to claim 1, wherein it is determined whether any of the states is in the undefined state. The determination means calculates a variation in the characteristic data in each state with respect to the reference data in each state based on the comparison result,
3. The update means for updating the reference data in each state stored in the storage means to correction reference data in which the variation calculated by the determination means is reduced, respectively. Tool attachment state detection device for machine tools in Japan. A programmable logic controller that controls the operation of the machine tool according to a predetermined control instruction,
The machine according to claim 2 or 3, wherein the programmable logic controller transmits a processing request command and receives the characteristic data in each state with the determination unit by I / O communication. Tool attachment state detection device in a machine.

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