JP2010157975A - Chattering removable device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chattering removable device capable of suppressing manufacture costs with a simple configuration. <P>SOLUTION: The device includes means for determining whether an MSB of the last shift register value stored in a temporary register R2 is 1. When the MSB of the last shift register value is 1 (S13;Yes), a counter C1 is made increment just by 1 (S14). A counter C2 is made increment just by 1 (S16) and the shift register value in the temporary register R2 is shifted to left by 1 bit (S17). It is determined whether a count value of the counter C1 is a chattering removable threshold N (e.g., 4), namely, whether the number of continuous 1 in the latest shift register value is 4. When the count value of the counter C1 is 4 (S18;Yes), it is determined that a touch sensor 75 is ON. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a chattering removing device that removes chattering from a detection signal of a sensor means for detecting presence or absence of contact with an object.

  Conventionally, a machine tool capable of numerical control (so-called NC control) has a desired machining (for example, “milling”) on a workpiece by independently moving the workpiece and a tool relative to each other in the XYZ rectangular coordinate system. ”,“ Drilling ”,“ cutting ”, etc.). After machining, the machine tool can mount a touch sensor on the spindle and measure the surface shape by bringing the touch sensor into contact with the surface of the workpiece.

  Such a machine tool includes an I / O unit that receives a detection signal indicating whether or not the touch sensor is in contact with the surface of the workpiece, and the X, Y, and Z axes of the touch sensor via the X, Y, and Z axis servo mechanisms. An X, Y, and Z axis servo amplifier that detects coordinate values, a control unit that controls the X, Y, and Z axis servo mechanisms, and the like are provided.

  While moving the table to which the workpiece is fixed by the X and Y axis servo mechanisms in the X axis direction and the Y axis direction, the spindle head and the touch sensor are moved up and down in the Z axis direction by the Z axis servo mechanism to Measure. The shape of the workpiece is measured from the position where the touch sensor is in contact with the workpiece or away from the workpiece. In the case of a touch sensor having a mechanical contact, chattering may occur at the contact.

  In this case, there is a possibility that a position where the touch sensor is in contact with the work or a position away from the work is erroneously detected. As a result, the measurement error of the surface shape data of the workpiece becomes large, and it is necessary to remove chattering from the detection signal of the touch sensor.

  Similarly, chattering may occur at the touch sensor contact portion even in the touch sensor of the tool breakage detection device that detects the breakage of the tool by contacting the tool used in the latest cutting process.

  The tool breakage detection device rotates the touch sensor during automatic tool change, and detects breakage of the tool depending on whether or not the touch sensor contacts the tool. When the tool is not broken and the touch sensor comes into contact with the tool, the detection value based on the detection signal of the touch sensor becomes “H”. However, when chattering occurs in the detection signal of the touch sensor, the touch sensor may erroneously detect, and the detection value may become “H” even when the tool is broken. As a result, there is a problem that the tool breakage detection accuracy decreases. Also in this case, it is necessary to remove chattering from the detection signal of the touch sensor.

  For example, Patent Document 1 discloses a chattering removal block that samples a key input signal at the rising edge of an internal clock and outputs the same value when a predetermined number of times are continuously input, and a chattering removal block. A chattering removal circuit including a shift register for delaying an input reset signal is disclosed. By providing the chattering removal circuit in the TV door phone image processing LSI, the chattering removal of the mechanical switch input signal input to the LSI is realized.

Japanese Patent No. 3168089

  The chattering removal circuit described in Patent Document 1 does not disclose any detailed configuration of the chattering removal block, but it is desirable that the chattering removal circuit can be realized with a simple configuration from the viewpoint of manufacturing cost.

  The objective of this invention is providing the chattering removal apparatus which can suppress manufacturing cost with a simple structure.

  The chattering removal apparatus according to claim 1 is a chattering removal apparatus that removes chattering from a detection signal of a sensor means that detects presence or absence of contact with an object, and receives a detection value based on a detection signal detected by the sensor means. For each communication cycle in which the I / O unit having a shift register that stores in time series, the control unit that is communicably connected to the I / O unit, and the I / O unit and the control unit communicate with each other, It is characterized by comprising reading means for reading the latest detection value from the shift register, and determination means for making a determination regarding chattering removal of the sensor means based on the detection value read by the reading means.

In this chattering removal apparatus, the detection value based on the detection signal detected by the sensor means is received by the shift register of the I / O unit and stored in time series. For each communication cycle in which the I / O unit and the control unit communicate with each other, the reading unit reads the latest detection value from the shift register.
Next, based on the detection value read by the reading unit, the determining unit makes a determination on chattering removal of the sensor unit.

  Specifically, the sensor means can be applied to a touch sensor for measuring a surface shape of a workpiece, a touch sensor of a tool breakage detection device, or the like. When applied to a touch sensor for surface shape measurement, erroneous determination of the touch sensor can be reduced by the determination unit performing determination regarding chattering removal of the touch sensor. When applied to the touch sensor of the breakage detection apparatus, erroneous detection of the touch sensor can be reduced as described above.

  According to a second aspect of the present invention, there is provided a chattering removal apparatus according to the first aspect of the invention, wherein the sensor means is a touch sensor capable of measuring a surface shape by contacting the surface of a workpiece, and the control unit reads from the shift register. Detection value storage means for accumulatively storing the issued detection values, and the determination means, the detection value read by the reading means during the previous communication cycle stored in the detection value storage means, Based on the latest detection value, when the detection value indicating that the touch sensor is in contact with the surface of the workpiece continues for a predetermined number of times, it is determined that the touch sensor is in contact with the surface of the workpiece. .

  The chattering removal device according to claim 3 is the invention according to claim 1, wherein the sensor means is configured by a touch sensor of a tool breakage detection device that detects breakage of a tool by contacting a tool used for the latest cutting, Based on the latest detection value read by the reading unit, the determination unit determines that the touch sensor is normal when a detection value indicating that the touch sensor has touched the tool is within a predetermined bit of the shift register. It is characterized by determining that it is detected.

  According to the invention of claim 1, an I / O unit having a shift register, a control unit connected to be communicable with the I / O unit, and a communication cycle in which the I / O unit and the control unit communicate with each other. Since the reading means for reading the latest detection value from the shift register and the determination means for making a determination related to the chattering removal of the sensor means based on the detection value, the chattering generated in the detection signal of the sensor means can be removed. .

  As the I / O unit and the control unit, those provided in the machine tool can be used, so that the chattering removal apparatus can be realized only by newly providing a shift register, a reading unit, and a determination unit. Thereby, since the chattering removal apparatus can be realized with a simple configuration, the manufacturing cost can be suppressed.

  According to the invention of claim 2, the sensor means is constituted by a touch sensor capable of measuring the surface shape by contacting the surface of the workpiece, the control unit has the detection value storage means, and the determination means is the detection value storage. If the detection value indicating that the touch sensor has touched the surface of the workpiece continues for a predetermined number of times based on the previous detection value stored in the means and the latest detection value, the touch sensor touches the surface of the workpiece. Therefore, when the surface shape is measured by bringing the touch sensor into contact with the surface of the workpiece, erroneous detection of the touch sensor can be reduced. Thereby, the measurement accuracy of the surface shape data of the workpiece can be improved.

  According to the invention of claim 3, the sensor means is constituted by a touch sensor of a tool breakage detection device, and the determination means determines that the touch sensor has contacted the tool based on the latest detection value read by the reading means. If the detected value is within a predetermined bit of the shift register, it is determined that the touch sensor is detecting normally, so the tool breakage detection device touch sensor is in contact with the tool used for the latest cutting process. When detecting breakage of the touch sensor, erroneous detection of the touch sensor can be reduced. Thereby, the breakage detection accuracy of a tool can be improved.

1 is an overall perspective view of a machine body of a machine tool according to an embodiment of the present invention. It is side views, such as a spindle head and an automatic tool changer. It is a block diagram which shows the control system of a machine tool. It is a timing chart of surface shape measurement of a work. (A) is explanatory drawing which shows the last shift register value, (b) is explanatory drawing which shows the newest shift register value. It is a flowchart of a position specific control program. It is a part of flowchart of a chattering removal control program. It is the remainder of the flowchart of a chattering removal control program. 6 is a block diagram illustrating a control system of a machine tool in Embodiment 2. FIG. (A) is a front view of a tool magazine, (b) is a side view of a tool magazine. It is a perspective view of the tool breakage detection apparatus with which the machine tool of Example 2 is provided. (A) is a disassembled perspective view of a tool breakage detection device, (b) is a front view of the tool breakage detection device with the case removed. It is a timing chart which shows the timing which the touch sensor turns on at the time of normal time and abnormality. It is a flowchart of the chattering removal control program in Example 2.

  Hereinafter, the best mode for carrying out the present invention will be described.

The present embodiment is an example when the present invention is applied to a machine tool M having a touch sensor 75 capable of measuring the surface shape by contacting the surface of a workpiece.
The configuration of the machine tool M will be described with reference to FIGS.
The machine tool M performs a desired machining (for example, “milling”, “drilling”, “cutting”) on the workpiece by moving the workpiece and the tool 6 relative to each other in the XYZ orthogonal coordinate system independently. Etc.).

As shown in FIG. 1, the machine tool M includes a base 1 that is a cast iron base, a machine body 2 that is provided on an upper part of the base 1, and that is fixed to the upper part of the base 1. The machine main body 2 and a box-like splash cover (not shown) that covers the upper part of the base 1 are mainly configured.
The base 1 is a substantially rectangular parallelepiped cast product that is long in the Y-axis direction (the lower right in FIG. 1 is the front of the machine tool M, and the Y-axis direction is the front-rear direction of the machine tool M).

Next, the machine body 2 will be described.
The machine body 2 is fixed to the column seat 3 on the rear portion of the base 1 and extends vertically upward, a spindle head 5 that can be moved up and down along the front surface of the column 4, and the spindle head 5. A main shaft 5A rotatably supported, an automatic tool changer (ATC) 7 provided on the right side of the main shaft head 5 and attaching and exchanging a tool holder of the tool 6 at the tip of the main shaft 5A; It is mainly composed of a table 8 that detachably fixes a work. A box-shaped control box 9 is provided on the back side of the column 4, and a control unit 20 (see FIG. 3) for controlling the operation of the machine tool is provided inside the control box 9.

Next, a moving mechanism that moves the table 8 in the X-axis direction and the Y-axis direction will be described.
As shown in FIGS. 1 and 3, the X-axis motor 71 and the Y-axis motor 72, which are servo motors, are arranged in the X-axis direction (the left-right direction of the machine body 2 in FIG. 1) and the Y-axis direction (the depth direction of the machine body 2). ) To move the table 8. This moving mechanism has the following configuration. First, a rectangular parallelepiped support 10 is provided below the table 8. The support base 10 is provided with a pair of X-axis feed guides extending along the X-axis direction, and the table 8 is movably supported on the pair of X-axis feed guides.

  A support base 10 is arranged on the upper side of the base 1, and the support base 10 is movably supported on a pair of Y-axis feed guides extending along the longitudinal direction of the base 1. An X-axis motor 71 provided on the support 10 moves and drives the table 8 in the X-axis direction along the X-axis feed guide, and a Y-axis motor 72 provided on the base 1 moves along the Y-axis feed guide along the Y-axis. The support 10 is driven to move in the direction.

  The X-axis feed guide is provided with telescopic covers 11 and 12 that contract telescopically on both the left and right sides of the table 8. In the Y-axis feed guide, a telescopic cover 13 and a Y-axis rear cover are provided before and after the support base 10, respectively. Even if the table 8 is moved in any of the X-axis direction and the Y-axis direction by these plural covers, the telescopic covers 11, 12, 13 and the Y-axis rear cover are always the X-axis feed guide and the Y-axis feed guide. Covering. The telescopic covers 11, 12, 13 and the Y-axis rear cover prevent chips and coolant liquid scattered from the processing area from falling on each rail.

Next, the elevating mechanism of the spindle head 5 will be described.
As shown in FIGS. 1 to 3, the spindle head 5 is supported by a guide rail extending in the vertical direction on the front side of the column 4 so as to be movable up and down via a linear guide. A Z-axis motor 73 composed of a servo motor drives the spindle head 5 up and down in the Z-axis direction (the vertical direction of the machine body 2 in FIG. 1).

  As shown in FIGS. 1 and 2, the automatic tool changer 7 holds a tool magazine 14 for storing a plurality of tool holders for supporting the tool 6, a tool holder attached to the spindle 5A, and other tool holders. A tool change arm 15 and the like.

Next, the electrical configuration of the control system of the machine tool M will be described.
As shown in FIG. 3, the control unit 20 includes a microcomputer, and includes a display interface (I / F) 24, communication interfaces (I / F) 25 and 27, and a servo interface (I / F). ) 26, CPU 21, ROM 22, RAM (detection value storage means) 23, and the like. A liquid crystal display 18 is connected to the display I / F 24, and an operation panel 19 is connected to the communication I / F 25. Servo amplifiers 30, 40, 50, and 60 are connected to the servo I / F 26, and an I / O unit 80 is connected to the communication I / F 27.

  The spindle servo amplifier 60 is connected to the spindle motor 74 and the spindle encoder 74a. The X-axis servo amplifier 30 is connected to the X-axis motor 71 and the X-axis encoder 71a, respectively. The Y-axis servo amplifier 40 is connected to the Y-axis motor 72 and the Y-axis encoder 72a, respectively. The Z-axis servo amplifier 50 is connected to a Z-axis motor 73 and a Z-axis encoder 73a, respectively. The I / O unit 80 is connected to a touch sensor 75 attached to the main shaft 5A.

  The X axis motor 71 and the Y axis motor 72 are for moving the table 8 in the X axis direction and the Y axis direction, respectively. The Z-axis motor 73 drives the spindle head 5 to move up and down in the Z-axis direction. The main shaft motor 74 is for rotating the main shaft 5A.

  The servo amplifiers 30, 40, 50, 60 are configured to include a microcomputer, and include servo interfaces (I / F) 34, 44, 54, 64 and motor interfaces (I / F) 35, 45, 55, 65, encoder interfaces (I / F) 36, 46, 56, 66, CPUs 31, 41, 51, 61, ROMs 32, 42, 52, 62, RAMs 33, 43, 53, 63, and the like.

  Servo amplifiers 30, 40 and 50 are connected via X, Y and Z axis servo mechanisms having X, Y and Z axis motors 71, 72 and 73 and X, Y and Z axis encoders 71a, 72a and 73a, respectively. X, Y, and Z axis coordinate values of the touch sensor 75 are detected. The RAMs 33, 43, and 53 store coordinate values detected in association with the X, Y, and Z axes, respectively.

  In order to reduce the load on the CPU 21 of the control unit 20, the control unit 20 is connected to the I / O unit 80 and the servo amplifiers 30, 40, 50, 60 so as to be able to communicate with each other at different communication cycles. Specifically, a communication cycle (servo amplifier communication cycle) between the servo amplifiers 30, 40, 50, 60 that need to be controlled with priority and the control unit 20 is set short, and the servo amplifiers 30, 40, 50, 60 are set. The communication cycle (I / O unit communication cycle) between the I / O unit 80 and the control unit 20 that does not need to be controlled as preferentially is set longer.

  The ROM 22 is a main control program for causing the machining program of the machine tool M to function, a control program for measuring the surface shape of the workpiece, a position specifying control program shown in the flowchart of FIG. 6, and chattering removal shown in the flowcharts of FIGS. A control program and the like are stored.

The RAM 23 stores the coordinate values detected by the servo amplifiers 30, 40, 50 in time series for each servo amplifier communication cycle. Further, the RAM 23 cumulatively stores detection values read from a shift register 81 described later for each IO unit communication cycle.
The control unit 20 reads the latest shift register value from the shift register 81 every I / O unit communication cycle, and based on the read shift register value, the communication cycle closest to the time when the touch sensor 75 touches the surface of the workpiece. Determine the time. Based on the determined communication cycle time and the coordinate value stored in the RAM 23, the control unit 20 determines the coordinate value at the communication cycle time as the surface shape data of the workpiece.

  The I / O unit 80 includes a communication interface (I / F) 82, a 4-bit shift register 81, and the like. The I / O unit 80 receives a detection value based on a detection signal indicating whether or not the touch sensor 75 touches the surface of the workpiece from the touch sensor 75, and the shift register 81 receives the detection value received from the touch sensor 75 in time series. Remember me. The cycle for storing the detection value in the shift register 81 is set to be shorter than the I / O unit communication cycle. The chattering removal device 70 includes a touch sensor 75, an I / O unit 80, and a control unit 20.

Next, measurement of the surface shape of the workpiece will be described with reference to FIG.
FIG. 4 is a timing chart of workpiece surface shape measurement executed by the control unit 20.
While the table 8 is moved in the X-axis and Y-axis directions by driving the X-axis motor 71 and the Y-axis motor 72, the spindle head 5 is moved in the Z-axis direction by driving the Z-axis motor 73 to measure the surface shape of the workpiece. Start. When the touch sensor 75 comes into contact with the surface of the workpiece, the detection signal from the touch sensor 75 becomes “H” level, and the I / O unit 80 receives this detection signal.

  The detection value based on this detection signal is taken in at the rising edge CK1 of the next shift register clock, and the shift register value becomes “0001”. Since this detection signal remains at “H” level, the detection value is captured at the rising edge CK2 of the shift register clock, and the shift register value becomes “0011”.

  Next, the control unit 20 starts communication with the I / O unit 80 at the falling edge of the I / O unit communication clock. Here, the control unit 20 reads the shift register value “0011” from the shift register 81 via the communication I / F 82 and stores it in the RAM 23.

  The detection values based on the detection signal of “H” level are taken in at the rising edges CK3 and CK4 of the shift register clock, respectively, and the shift register values become “0111” and “1111”. Similarly, the detection value based on the detection signal at the “H” level is taken in at the rising edges CK5 and CK6 of the shift register clock, and the shift register value is maintained at “1111”. At this time, the shift register 81 stores the acquired detection value as the shift register value after the previous shift register value “0011” stored in the RAM 23.

  Next, the control unit 20 starts communication with the I / O unit 80 at the falling edge of the I / O unit communication clock. Here, the control unit 20 reads out the shift register value “1111” from the shift register 81 via the communication I / F 82, and cumulatively stores it in the RAM 23.

  At this time, the control unit 20 reads the shift register value “0011” read in the previous communication cycle stored in the RAM 23 shown in FIG. 5A and the latest shift register value “1111” shown in FIG. The chattering is removed from the detection signal of the touch sensor by determining whether or not the touch sensor is in contact with the surface of the workpiece based on the above. Details will be described next.

Next, the position specifying control executed by the control unit 20 will be described based on the flowcharts of FIGS. In the figure, Si (i = 1, 2,...) Indicates each step. This position specifying control is executed continuously by the control unit 20 when measuring the surface shape of the workpiece.
When the control unit 20 starts position specifying control, chattering removal processing is first executed (S1).

When the chattering removal process is started, the register values of the temporary registers R1, R2 are reset to 0, and the counter values of the counters C1, C2, C3 are reset to 0 (S10).
In the case of the communication timing between the control unit 20 and the I / O unit 80, specifically, the latest shift register value is stored in the temporary register R1 at the falling edge of the I / O unit communication clock (S11; Yes). . At this time, if the shift register value acquired in the previous communication (hereinafter referred to as the previous shift register value) is stored in the temporary register R1, the previous shift register value is first stored in the temporary register R2. After that, the latest shift register value is stored in the temporary register R1.

  Next, it is determined whether the MSB (most significant bit) of the previous shift register value stored in the temporary register R2 is 1. When the MSB of the previous shift register value is 0 (S13; No), the counter C1 is reset to 0 (S15), and the process proceeds to S16. When the MSB of the previous shift register value is 1 (S13; Yes), the counter C1 is incremented by 1 (S14).

  The counter C2 is incremented by 1 (S16), and the shift register value of the temporary register R2 is shifted left by 1 bit (S17). The counter C1 is a counter that counts the number of consecutive “1” s in the MSB of the shift register value, and the counter C2 is a counter that counts the number of searched bits in the previous shift register value.

  It is determined whether the count value of the counter C1 is the chattering removal threshold value N (4 in the present embodiment), that is, whether the number of consecutive “1” s in the latest shift register value is 4. When the count value of the counter C1 is 4 (S18; Yes), it is determined that the touch sensor 75 is turned on, and the process proceeds to S2. On the other hand, if the count value of the counter C1 is not 4 (S18; No), whether or not the counter value of the counter C2 has become the shift register length L (4 in this embodiment), that is, with respect to the previous shift register value. It is determined whether or not the search is finished. When the counter value of the counter C2 is not 4 (S20; No), the process returns to S13.

  When the counter value of the counter C2 is 4, since the search for the previous shift register value is finished, the counter value of the counter C2 is reset to 0 (S21), and then the latest shift register value is searched. Do. Next, it is determined whether or not the MSB of the latest shift register value stored in the temporary register R1 is 1. When the MSB of the latest shift register value is 0 (S22; No), the counter C1 is reset to 0 (S24), and the process proceeds to S25. If the MSB of the latest shift register value is 1 (S22; Yes), the counter C1 is incremented by 1 (S23).

  The counter value of the counter C3 is incremented by 1 (S25), and the shift register value of the temporary register R1 is shifted left by 1 bit (S26). The counter C3 is a counter that counts the number of searched bits in the latest shift register value. It is determined whether or not the counter value of the counter C1 is 4, that is, whether or not the number of consecutive “1” s in the latest shift register value and the previous shift register value is 4. If the count value of the counter C1 is not 4 (S27; No), it is determined whether or not the counter value of the counter C3 is 4. When the counter value of the counter C3 is not 4 (S28; No), the process proceeds to S22.

  When the counter value of the counter C3 is 4 (S28; Yes), since the search for the latest shift register value is completed, the counter values of the counters C1 and C3 are reset to 0 (S29), and the process returns to S11. . On the other hand, when the count value of the counter C1 is 4 (S27; Yes), it is determined that the touch sensor 75 is turned on because “1” continues for 4 times in the shift register value (S19), and the process proceeds to S2.

  Next, in S2, it is determined whether or not the counter C3 is zero. When the counter C3 is 0 (S2; Yes), that is, when “1” continues four times in the previous shift register value, the time T when the touch sensor 75 is turned on is expressed as T = ((L−C2) + N + L ) Obtained from t (S3). Here, t is a shift register clock period.

  On the other hand, when the counter C3 is not 0 (S2; No), that is, when “1” continues four times over the latest shift register value or the previous shift register value and the latest shift register value, The time T when the touch sensor 75 is turned on is obtained from T = ((L−C3) + N) t (S4).

  Based on the time T obtained in S3 or S4, the coordinate value before T time is output to the display 18 as the touch position (S5), and then the process returns to the start. Here, as shown in FIG. 4, the coordinate value P4 is displayed on the display 18. The CPU 21 that executes S12 of the flowchart shown in FIG. 7 corresponds to a reading unit, and the CPU 21 that executes S18 and S19 of the flowchart shown in FIG. 7 and S27 of the flowchart shown in FIG.

Next, the operation and effect of the chattering removal apparatus 70 described above will be described.
In the chattering removal device 70, when the touch sensor 75 comes into contact with the surface of the workpiece when measuring the surface shape of the workpiece, the shift register 81 receives the detection signal from the touch sensor 75 in the I / O unit 80 and stores it in time series. . Meanwhile, the servo amplifiers 30, 40, 50 detect the X, Y, Z axis coordinate values of the touch sensor 75 via the X, Y, Z axis servomechanism, and the RAM 23 in the control unit 20 is detected at each servo amplifier communication cycle. The X, Y, and Z axis coordinate values of the touch sensor 75 are stored in time series.

  For each I / O unit communication cycle in which the I / O unit 80 and the control unit 20 communicate, the latest detection value is read from the shift register 81 and stored in the RAM 23 cumulatively. When the detection value indicating that the touch sensor 75 has touched the surface of the workpiece continues for a predetermined number of times based on the previous detection value stored in the RAM 23 and the latest detection value read from the shift register 81, the touch is performed. It is determined that the sensor 75 is in contact with the surface of the workpiece. Thereby, since chattering can be removed from the detection signal of the touch sensor 75, erroneous detection of the touch sensor 75 can be reduced. Therefore, the measurement accuracy of the workpiece surface shape data can be improved.

  As the I / O unit 80 and the control unit 20, those provided in the machine tool M can be used. Therefore, the chattering removing device 70 can be realized only by newly providing the shift register 81. Thereby, since the chattering removal apparatus 70 is realizable with a simple structure, manufacturing cost can be suppressed.

Next, a second embodiment of the present invention will be described with reference to FIGS. However, the same reference numerals are given to the same components as those in the above embodiment, and only different components will be described.
In the second embodiment, the present invention is applied to a machine tool M having a tool breakage detecting device 97 that detects a breakage of the tool 6 by contacting the tool 6 used in the latest cutting.

  As shown in FIG. 9, the I / O unit 80 includes a communication interface (I / F) 82, a 25-bit shift register 81A, and the like. The I / O unit 80 receives a detection value from the touch sensor 108 based on a detection signal indicating whether or not the touch sensor 108 is in contact with the tool 6 when the breakage of the tool 6 is detected. The shift register 81A stores the detection value received from the touch sensor 108 in time series. The control unit 20 </ b> A includes an axis control unit 110 in addition to the configuration of the control unit 20. A magazine motor 76, a linear drive motor 99, and a needle turning motor 107 are connected to the shaft control unit 110, respectively. The chattering removal device 70 includes a touch sensor 108, an I / O unit 80, and a control unit 20A.

The tool breakage detection device 97 disposed in the tool magazine 14 of the automatic tool changer 7 will be described. First, the structure of the tool magazine 14 will be described.
As shown in FIG. 10A, the tool magazine 14 includes a plurality of tool pots 83, and the tool pots 83 are mounted on a transfer mechanism 85 disposed inside the magazine base 84.

  The transfer mechanism 85 includes a pair of sprockets 86 and 87 rotatably arranged inside the magazine base 84, an endless chain 88 spanned between the sprockets 86 and 87, and an outer peripheral side of the chain 88. A bracket 89 and the like fixed to the head are provided. The plurality of tool pots 83 are each attached to a bracket 89, and when one sprocket 86 is rotationally driven by the magazine motor 76, the path circulating with the chain 88 is transferred.

  The plurality of tool pots 83 are all attached to the bracket 89 so as to be rotatable. However, the inner wall surface 84a of the outer peripheral portion of the magazine base 84 is used as the tool in the most part of the transfer path of the tool pot 83. The pot 83 is in contact. Therefore, the inner wall surface 84a is in a state of restricting the rotation of the tool pot 83, and the tool pot 83 maintains a state in which the tool 6 is directed to the front as shown in FIG. To do.

  On the other hand, a split outlet 84b is formed on the lower end side of the magazine base 84, and the tool pot 83 removes the tool 6 from the retracted state only at a position where the split outlet 84b is formed (hereinafter referred to as an index position). It can be rotated to a downward direction (a state indicated by a two-dot chain line in the figure; hereinafter referred to as a replaceable state). A tilting mechanism (not shown) for rotating the tool pot 83 to the retracted state or the replaceable state is disposed at the index position.

  An actuator case 90 is provided on the upper portion of the magazine base 84, and a magazine motor 76 for driving the sprocket 86 and the like are accommodated in the actuator case 90. The magazine motor 76 is controlled by the shaft controller 110.

  As shown in FIGS. 11, 12 (a), and 12 (b), in the tool breakage detection device 97, a motor cover 100 incorporating a linear drive motor 99 is provided inside the cases 98 </ b> L and 98 </ b> R. The linear drive motor 99 is controlled by the shaft controller 110. A pinion 101 is attached to the rotation shaft of the linear drive motor 99, and the pinion 101 is engaged with a rack 103 for linearly displacing the contact sensor unit 102.

  A holder 104 that extends downward is attached to the side surface of the rack 103, and a contact sensor unit 102 is attached to the tip of the holder 104. A guide stay 105 for attaching the tool breakage detecting device 97 to the tool magazine 14 is incorporated on the base end side of the cases 98L and 98R. Here, the linear drive motor 99, the pinion 101, and the rack 103 constitute a linear actuator 106.

  That is, when the linear drive motor 99 rotates the pinion 101, the contact sensor unit 102 together with the rack 103 is held in the longitudinal direction of the tool breakage detection device 97, that is, the tool pot 83, and the length of the tool 6 in the retracted state. Move linearly along the direction. The contact sensor unit 102 has a built-in needle turning motor 107, and turns a detection needle (touch sensor) 108 as a sensor means attached to the rotating shaft of the needle turning motor 107 to contact the tool 6. Whether the tool 6 is broken or not is detected. The needle turning motor 107 is controlled by the shaft control unit 110.

  For example, when the touch sensor 108 turns from the horizontal position, which is the initial position, the touch sensor 108 is turned on when the touch sensor 108 comes in contact with the tool 6 (such as the drill 6a) and stops turning halfway. On the other hand, when the tool 6 breaks and the touch sensor 108 turns to the final position without stopping, the touch sensor 108 detects the breakage of the tool 6 without turning on.

  FIG. 13 is a timing chart showing the timing at which the touch sensor 108 is turned on during normal and abnormal times. When the breakage of the tool 6 is detected, the time when the touch sensor 108 is in the initial position is 0, and when the tool 6 is broken, the time when the touch sensor 108 turns to the final position is t25. When the tool 6 is not broken and the touch sensor 108 comes into contact with the tool 6, the detection value based on the detection signal of the touch sensor 108 becomes “H”. However, if chattering occurs in the detection signal of the touch sensor 108, the touch sensor 108 may detect it incorrectly, and the detection value may become “H” even when the tool 6 is broken.

Therefore, in this embodiment, it is assumed that the touch sensor 108 is operating normally when the touch sensor 108 is turned on between t9 and t15 (a region indicated by hatching in FIG. 13).
When the touch sensor 108 is turned on at other times, it is assumed that the touch sensor 108 is erroneously detected. In particular, the case where the touch sensor 108 is turned on between t0 and t9 is “abnormal 1”, and the case where the touch sensor 108 is turned on between t15 and t25 is “abnormal 2”.

  The shift register 81A receives detection values from the touch sensor 108 at timings t1, t2,. At time t25, the detection values received at t1, t2,..., t25 are stored in the respective bits of the shift register 81A. The control unit 20A reads the detection value stored in the shift register 81A at the falling edge of the next I / O unit communication clock.

Next, chattering removal control executed by the control unit 20A will be described based on the flowchart of FIG. In the figure, Si (i = 30, 31...) Indicates each step.
The chattering removal control is executed by the control unit 20A when the turning of the touch sensor 108 is completed when the breakage of the tool 6 is detected.

  When the control unit 20A starts chattering removal control, the counter values of the counters D and E are reset to 0 (S30). In the case of communication timing between the control unit 20A and the I / O unit 80 (S31; Yes), the shift register value is read (S32). If the MSB of the read shift register value is 0, that is, if the touch sensor 108 is not ON (S33; Yes), the count value of the counter E is incremented by 1 (S35), and then the count value of the counter D is set to 1. (S34), and the process proceeds to S36.

  When the MSB of the read shift register value is 1, that is, when the touch sensor 108 is turned on (S33; Yes), the counter value of the counter D is incremented by 1 (S34). Next, it is determined whether or not the counter value of the counter D is the register length M of the shift register value (25 in this embodiment). If the counter value of the counter D is not 25, that is, if the search for the read shift register value is not completed (S36; No), the shift register value is shifted left by 1 bit (S37), and the process returns to S33. The counter D is a counter that counts the number of bits of the searched shift register value, and the counter E is a counter that counts the continuous number of “0” in the MSB of the shift register value.

  On the other hand, when the counter value of the counter D is 25 (S36; Yes), since the search for the shift register value is completed, whether or not the count value of the counter E is larger than the lower limit threshold value P (10 in this embodiment). Determine. When the count value of the counter E is 10 or less (S38; No), a message of “abnormal 1” is displayed on the display 18 (S39), and this process is terminated.

When the count value of the counter E is larger than 10 (S38; Yes), it is next determined whether or not the count value of the counter E is larger than the upper limit threshold value Q (15 in this embodiment).
When the count value of the counter E is larger than 15 (S40; Yes), a message of “abnormal 2” is displayed on the display 18 (S41), and this process is terminated. When the count value of the counter E is 15 or less (S40; No), a “normal” message is displayed on the display 18 (S42), and this process is terminated. Note that the CPU 21 that executes S32 of the flowchart shown in FIG. 14 corresponds to a reading unit, and the CPU 21 that executes S38 to S42 of the flowchart shown in FIG. 14 corresponds to a determination unit.

  As described above, when the detection value indicating that the touch sensor 108 is in contact with the tool 6 is within a predetermined bit of the shift register 81A based on the shift register value read by the control unit 20A, the touch sensor 108 is normally detected. It is determined that Therefore, erroneous detection of the touch sensor 108 when detecting breakage of the tool 6 can be reduced, and breakage detection accuracy of the tool 6 can be improved.

Next, a modified example in which the above embodiment is partially modified will be described.
1] In the first embodiment, in addition to the 4-bit shift register 81, a shift register having a different number of bits such as an 8-bit shift register may be used. When the 8-bit shift register is applied and the chattering removal threshold N is 4, the 8-bit shift register stores the previous shift register value and the latest shift register value. Therefore, when the control unit 20A reads the shift register value from the 8-bit shift register for each I / O unit communication cycle, it is not necessary to store it in the RAM 23.

20, 20A control unit 21 CPU
23 RAM
70 Chattering removal device 75, 108 Touch sensor 80 I / O unit 81, 81A Shift register 97 Tool breakage detection device

Claims (3)

In the chattering removal device for removing chattering from the detection signal of the sensor means for detecting the presence or absence of contact with the object,
An I / O unit having a shift register that receives a detection value based on a detection signal detected by the sensor means and stores the detection value in time series;
A control unit communicably connected to the I / O unit;
Reading means for reading the latest detection value from the shift register for each communication cycle in which the I / O unit and the control unit communicate with each other.
A chattering removal apparatus comprising: a determination unit configured to make a determination regarding chattering removal of the sensor unit based on the detection value read by the reading unit. The sensor means is composed of a touch sensor capable of measuring the surface shape by bringing it into contact with the surface of the workpiece,
The control unit has detection value storage means for cumulatively storing the detection values read from the shift register,
The determination means is based on the detection value read by the reading means in the previous communication cycle stored in the detection value storage means and the latest detection value, and the touch sensor has contacted the surface of the workpiece. 2. The chattering removal apparatus according to claim 1, wherein when the detection value indicating that the touch sensor has continued for a predetermined number of times, it is determined that the touch sensor is in contact with the surface of the workpiece. The sensor means is composed of a touch sensor of a tool breakage detection device that detects breakage of a tool by contacting a tool used in the latest cutting process,
Based on the detection value read by the reading means, the determination means detects that the touch sensor normally detects that the detection value indicating that the touch sensor has touched the tool is within a predetermined bit of the shift register. The chattering removal apparatus according to claim 1, wherein the chattering removal apparatus according to claim 1 is determined.