JP6322076B2 - Tool breakage or workpiece detection device - Google Patents

Description

  The present invention relates to a device for detecting a breakage of a tool such as a drill for machining a workpiece or a workpiece as a detection target, the presence or absence of the detection target, and outputting the detection result to the outside. The present invention relates to a tool breakage or workpiece detection device using a stepping motor as an actuator for driving (contact probe).

  In addition to the contact detection method, there is a non-contact detection method using optics, ultrasonic waves, vibration, etc. as a method for detecting the presence or absence of tool breakage and workpiece presence. The conventional technology will be outlined for a method of detecting whether a tool such as a drill is broken by a contact method.

  The method of detecting the presence or absence of tool breakage by contact type can be broadly classified into a switch detection type, a current detection type, and an optical encoder detection type (see, for example, Patent Document 1 for the switch detection type).

  In the case of the switch detection type, for example, a sensor (a sensor having a mechanical contact or an electronic contact) is provided at the origin position and the end position of a detector (hereinafter referred to as “needle”) attached to the rotating shaft, and the needle rotates. After the start, it is detected whether or not the needle has reached the end point position, and whether or not the tool is broken is checked.

  In the case of the current detection type, for example, an increase in the motor winding current when the needle collides with the tool is analyzed to check whether the tool is broken.

  In the case of the optical encoder detection type, the disappearance of the encoder pulse when the encoder collides with the tool is monitored to check whether the tool is broken.

JP 2005-329529 A

As a device that detects whether a tool is broken (or the presence or absence of a workpiece) by a contact method, the above-described method has been conventionally employed. However, the conventional device has the following problems.
(Problem 1)
A DC motor is generally used as an actuator for rotationally driving the needle. However, the DC motor has a problem of short life due to brush wear.

  Although the use of a motor without a brush is conceivable, for example, when an AC servo motor, a DC brushless motor, or a stepping motor is used, there are the following problems.

  AC servo motors and DC brushless motors are expensive and complicated to control.

Stepping motors are inexpensive but have a phenomenon unique to stepping motors such as step-out, which may cause malfunction.
(Problem 2)
Since the gear for optimizing the torque and the rotational speed is worn by the impact at the time of tool contact, short life becomes a problem.
(Problem 3)
The switch detection type and the current detection type require a sensor corresponding to the detection angle (see, for example, the angle detection light sensors 59 to 61 in Patent Document 1), which increases the management cost.
(Problem 4)
The life of the sensor of the mechanical contact in the switch detection type becomes a problem.
(Problem 5)
The optical encoder detection type has a problem of malfunction due to loose coupling of the encoder connecting portion and shaft misalignment.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to reduce the mechanical consumable part as compared with the prior art to improve durability and reduce costs, and to provide a stepping motor. An object of the present invention is to provide a tool breakage or workpiece detection device capable of solving the problem relating to the step-out when using the tool.

The present invention relates to a tool breakage or workpiece detection device, and the above object of the present invention is to detect the breakage of a tool for machining a workpiece or the presence or absence of the detection target by using a workpiece as a detection target. A tool breakage or workpiece detection device comprising: a sensing head for controlling the operation of the sensing head; and a control unit having a function of outputting a detection result indicating the presence or absence of the detection target to an external device. There,
The sensing head is
A contact-type detector that is rotatable within a predetermined angle range from an origin position to an end position including a fan-shaped detection range, a stepping motor as an actuator that drives the detector to rotate, and the current position of the detector A magnetic encoder as a sensor for detecting the position and a photo sensor for detecting the origin position,
The control unit is
A control unit for controlling the rotation of the detector by feedback control of the stepping motor and controlling communication with the external device;
The controller is
Control for controlling rotation of the detector in a predetermined acceleration / deceleration pattern, with the period until the detector reaches the end point in a state where the stepping motor is not out of step as a reference drive period of the detector And determination means for determining the presence or absence of the detection object by detecting whether the detector and the tool or the workpiece are in contact with each other within the reference drive period based on the output of the magnetic encoder. The contact between the detector and the tool or the workpiece is not detected by the determination means, and it is determined that the detector has not reached the upper limit of the detection range within the reference driving period. In this case, the excitation pulse continues to be output until the detector reaches the upper limit of the detection range without stopping the output of the excitation pulse to the stepping motor when the reference drive period has elapsed. A desynchronization allowable control means for controlling to continue the determination processing by the determination means, it is achieved by having a.

Furthermore, the above object of the present invention is to
The excitation pulse that the step-out allowable control means continues to output after the elapse of the reference drive period is an excitation pulse for step-out allowable control that rotates the detector at the lowest speed in the variable speed range of the detector. The step-out allowable control means outputs the excitation pulse to the stepping motor until contact between the detector and the tool or the workpiece is detected or until the detector reaches the upper limit of the detection range. To continue,
A step-out allowable control timer that defines the duration of driving of the stepping motor when the step-out occurs is provided, and the control means is configured so that the detector and the tool or the workpiece are not in contact with each other. If the step-out allowable control timer times out, it is determined that a significant step-out has occurred so that the detector does not rotate, and the output of the excitation pulse is stopped and alarm information indicating the occurrence of an abnormality is displayed. Outputting to the external device;
Before the rotation control with the predetermined acceleration / deceleration pattern, the stepping motor is prevented from being stepped out by performing a control for rotating the detector for a predetermined time at the lowest speed of the variable speed range of the detector. Further comprising step-out prevention control means for
The step-out prevention control means, when returning the position of the detector to the origin position, performs control to rotate the detector at the lowest speed of the variable speed range of the detector,
The step-out prevention control means performs control not to operate the stepping motor for a certain period after the detection operation by the detector is set in a standby state and after the determination of the presence or absence of the detection target;
The control unit inputs, as setting information from the operation unit or the external device, an angle range from the origin position to the end position and change information of the rotation speed of the detector, or any one change information, Further comprising control information adjustment means for adjusting control information related to rotation control of the detector based on the input change information;
Are more effectively achieved by each.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to solve the subject regarding a step-out at the time of utilizing a stepping motor while improving a durability and reducing cost by reducing a mechanical consumable part from the past. In detail, according to this invention, there can exist the following effects.

1. Effects of using a stepping motor (1)
In the present invention, since the stepping motor is used as the actuator for rotationally driving the detector, the durability can be improved. In other words, unlike a DC motor, a stepping motor does not have a brush, so there is no problem of wear and a long life can be realized. In addition, since stepping motors are less expensive than AC servo motors and DC brushless motors, costs can be reduced.

2. Effect of Stepping Motor Out-of-Step Allowance Control In the present invention, even in a state where the detector has not reached the upper limit of the detection range within the reference drive period, that is, in a state where out-of-step occurs in the stepping motor, the excitation pulse Without stopping the output of the sensor, the excitation pulse continues to be output until the detector reaches the upper limit of the detection range. Can be detected. Therefore, it is possible to prevent malfunction during step-out and improve the durability of the detection device against step-out.

  And in the control mode provided with a step-out allowance control timer, the control is allowed except for a significant step-out that can be regarded as a collision between the detector and the tool or workpiece, and only when there is a significant step-out. Since the detection operation is stopped, it is possible to detect the presence / absence of a detection target except in a step-out state where the needle 11 does not rotate.

  Also, in the out-of-step allowable control, by setting the detector to rotate at the lowest speed of the variable speed range of the detector, the occurrence of the step-out can be suppressed and the durability against the step-out Can be further improved.

3. Effect of using stepping motor (2)
In the present invention, the use of a stepping motor having an appropriate rotational speed and torque results in a structure that does not require a gear, and damage due to gear wear does not occur. Therefore, compared with a conventional apparatus that requires a gear for optimizing torque and rotation speed, it is possible to reduce the mechanical consumable part as compared with the conventional apparatus and improve the durability of the apparatus.

4). Effects of using a magnetic encoder (1)
In the present invention, since a magnetic encoder is used as a sensor for detecting the current position of the detector, it is possible to improve the durability and prevent malfunction due to the shaft misalignment of the coupling unit of the conventional apparatus. be able to. That is, since the magnetic encoder does not require a mechanical connection portion such as a coupling with respect to the motor rotation shaft, the shaft of the coupling portion does not shift.

5. Effect of using magnetic encoder (2)
In the present invention, since the position is detected by the encoder, it is possible to cope with all detection angles with one type of sensor. Therefore, compared with the conventional apparatus provided with the some optical sensor according to a detection angle, management cost can be reduced.

6). Effect of use of photo sensor In the present invention, since the origin position is detected by an electronic contact using a photo sensor, the durability is improved as compared with a conventional device that detects by a mechanical contact. Can be made.

It is a schematic diagram which shows an example of the whole structure containing the tool breakage which concerns on this invention, or a workpiece | work detection apparatus. It is a schematic diagram which shows an example of the internal structure of the sensing head which concerns on this invention. It is a schematic diagram for demonstrating the relationship between the swing angle of the needle which concerns on this invention, and the detection range of a tool. It is a schematic diagram for demonstrating the step-out allowance control which concerns on this invention. It is a flowchart for demonstrating the operation | movement outline | summary of the tool breakage which concerns on this invention, or a workpiece | work detection apparatus. It is a 1st flowchart for demonstrating main operation | movement of the tool breakage which concerns on this invention, or a workpiece | work detection apparatus. It is a 2nd flowchart for demonstrating main operation | movement of the tool breakage which concerns on this invention, or a workpiece | work detection apparatus. It is a 3rd flowchart for demonstrating main operation | movement of the tool breakage or workpiece | work detection apparatus which concerns on this invention. It is a 4th flowchart for demonstrating main operation | movement of the tool breakage which concerns on this invention, or a workpiece | work detection apparatus. It is a 5th flowchart for demonstrating main operation | movement of the tool breakage or workpiece | work detection apparatus which concerns on this invention. It is a 6th flowchart for demonstrating main operation | movement of the tool breakage which concerns on this invention, or a workpiece | work detection apparatus.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing an example of an overall configuration including a tool breakage or workpiece detection device (hereinafter abbreviated as “detection device”) according to the present invention.

  The detection device according to the present invention is a device having a function of inspecting the breakage of a tool for processing a workpiece or the presence of the detection target by using a contact method, and outputting the inspection result to the outside. .

  In addition, since the detection method of the “tool breakage” or “workpiece” that is the detection target is the same, in the following description, a case where the tool breakage is set as the detection target will be described as an example for convenience of explanation. The description of the case where the workpiece is the detection target is omitted.

  In FIG. 1, the detection device includes a sensing head 10 having a contact-type detector 11 for detecting the presence or absence of breakage of a tool 1 (such as a cutting edge of a drill), a control unit 20 that controls the operation of the detector 11, It is configured with.

  The sensing head 10 includes an actuator 12 for rotationally driving the detector 11, a magnetic sensor 13 (ME) as a position detection sensor for detecting a moving position (current position) of the detector 11, and the detector 11. And an input / output unit 15 for transmitting and receiving information to and from the control unit 20.

  In the present embodiment, the detector 11 is a detector that rotates around the rotation shaft 12a, and is configured by a rod-shaped needle 11 or a plate-like plate as shown in FIG. The actuator 12 uses a stepping motor, and the position detection sensor 13 uses a magnetic encoder.

  Hereinafter, the components of the sensing head 10 include a detector 11 as a “needle 11”, an actuator 12 as a “stepping motor 12” or abbreviated as “motor 12”, and a position detection sensor 13 as a “magnetic encoder 13” or abbreviated. The electronic sensor 14 for detecting the origin position of the needle 11 as “encoder 13” will be described as “origin sensor 14”.

  2A to 2C are schematic views showing an example of the internal structure of the sensing head 10, FIG. 2A is a view showing the arrangement of the magnetic encoder 13, and FIG. 2B is a stepping. FIG. 2C is a view showing the arrangement of the motor 12 and the origin sensor 14, and FIG. 2C is a view of FIG.

  The magnetic encoder 13 detects the current position that is the current rotation angle from the origin position of the needle 11 based on the change in the direction of the magnetic field accompanying the rotation of the magnetic body fixed to the rotor shaft of the stepping motor 12. It is an encoder for doing. The origin sensor 14 is an electronic device that outputs a detection signal when the origin position detection member fixed to the rotor shaft (or connecting shaft) of the stepping motor 12 is positioned at the origin position of the needle 11 in this example. It is a sensor. In the present embodiment, the detection signal is output by turning on the origin position output when the needle 11 is located at the origin position by the on / off control of the switching element.

  The needle 11 is detachably attached to the distal end portion of the rotating shaft 12a protruding from the sensing head main body 10A via a fixture 11a as shown in FIG. The sensing head main body 10A is installed at a position where the tool to be inspected (a normal tool 1 without breakage) and the needle 11 abut within the detection range.

  The outer diameter of the sensing head body 10A is, for example, about φ30 × 130 mm, and the outer diameter of the needle 11 is, for example, a standard type having a diameter of about 1.2 mm and a length of about 150 mm.

  Next, the configuration of the control unit 20 will be described with reference to FIG.

  The control unit 20 is communicably connected to the sensing head 10 via an information transmission means 15a such as a connection connector or a communication cable.

  In the present embodiment, the control unit 20 controls the rotation of the detector 11 by feedback control of the stepping motor 12 and communicates with an external device (an external control device such as a PLC (Programmable Logic Controller) or a PC) 30. Control unit 21 that performs control, input / output unit 22 that transmits and receives information to and from sensing head 10, storage unit 23 that stores control information and inspection results, determination results and alarms on whether or not a tool is broken A display unit 24 for displaying the state in a visually recognizable manner, and an operation unit 25 for setting the swing angle of the needle 11 (range of rotation angle from the origin position to the end point position: also called “angle range”) and the rotation speed. I have.

  The control unit 21 includes, for example, a control circuit, an excitation pulse generation circuit, and the like, and rotates the needle 11 at a predetermined angle range and a predetermined rotation speed by driving control of the stepping motor 12 by an excitation pulse (hereinafter referred to as “command pulse”). Dynamic control is used. The main functions of the control unit 21 will be described later.

  The display unit 24 and the operation unit 25 are components used for initial setting at the time of introduction of the detection device and when an abnormality occurs.

  The display unit 24 includes, for example, a monitor LED (Light Emitting Diode), and the operation unit 25 includes, for example, an angle setting rotary switch capable of setting the swing angle of the needle 11 stepwise, and the rotation speed ( For example, it is configured to include a speed setting rotary switch that can be set in a stepwise manner and a swing button for confirming the operation of the needle 11. In the present embodiment, the angle range (swing angle) of the needle 11 can be set in a plurality of steps (for example, 10 steps) within a range of 45 to 180 ° from 0 ° horizontally to vertically upward with respect to the rotating shaft 12a. It is said. The rotation speed of the needle 11 can be set in a plurality of steps (for example, 10 steps) in a range of 50 to 140% of a preset reference speed.

  The main reason that the angle range of the needle 11 can be adjusted is that the tool to be inspected used in various machine tools, tool changers, and the like has various tool positions and inspection locations, and the degree of freedom of the tool detection range. In this example, the angle range of the needle 11 can be adjusted by manual operation.

  The main reason why the rotation speed of the needle 11 can be changed is, for example, that the tool may be damaged if the rotation speed is high in the case of a small-diameter tool. The rotation speed (maximum speed, etc.) can be adjusted manually.

  Here, an example of a method for attaching the sensing head 10 and the control unit 20 will be described.

  The sensing head 10 is fixed by, for example, passing a cylindrical main body 10A through a through hole formed in the mounting portion and tightening with a mounting nut (see nut 10a in FIG. 2) from both sides of the through hole. .

  The control unit 20 has a fitting groove for fitting with the DIN rail formed at a predetermined position of the control unit 20, and is fixed by, for example, fitting the fitting groove into the DIN rail fixed to the mounting portion. .

  Next, the functional configuration of the control unit 21 will be described.

  1 is a block diagram illustrating the functional configuration of the control unit 21, and each function (means) included in the control unit 21 will be described with reference to FIG.

  As shown in FIG. 1, the control unit 21 includes, as main means, a needle operation control means 21a, a step-out allowance control timer 21b, a detection target presence / absence determination means 21c, a step-out prevention control means 21d, and a step-out allowance control means. 21e, control information adjusting means 21f, and external communication means 21g. For convenience of explanation, these means are classified by function with the name of the means, and do not limit the hardware configuration or software configuration.

  Hereinafter, each of the above-described means 21a to 21g will be sequentially described.

(1) Needle operation control means 21a
The needle operation control means 21a is means for controlling the rotation of the needle 11 by feedback control of the stepping motor 12. In the present embodiment, the needle 11 is controlled by driving control of the stepping motor 12 by command pulses (excitation pulses). The rotation is controlled in an angular range and a predetermined rotation speed.

  In the present embodiment, the angle range (swing angle) and the rotation speed of the needle 11 can be adjusted by manual operation as described above.

  Here, the relationship between the swing angle of the needle 11 and the tool detection range will be described with reference to the schematic diagrams of FIGS.

  FIG. 3A shows the detection range when the setting of the swing angle is 60 to 180 °, and FIG. 3B shows the detection range when the setting of the swing angle is 45 °.

  The needle 11 according to the present embodiment is a contact-type detector that is rotatable within a predetermined angle range from an origin position to an end position including a fan-shaped detection range, and changes the setting of the predetermined angle range (swing angle). It is possible. The detection range is determined according to the setting of the swing angle.

  For example, when the setting of the swing angle is 60 to 180 °, as shown in FIG. 3A, the tool detection range θ (θ1) is 15 ° from the origin position (origin sensor position) and from the end position. The range excluding 20 °.

  When the swing angle is set to 45 °, as shown in FIG. 3B, the tool detection range θ (θ2) is 15 ° from the origin position (origin sensor position) and 7. The range excluding 5 °.

  In the needle operation control means 21a, the needle 11 is controlled to rotate at a predetermined rotational speed until the needle 11 reaches the upper limit Pe of the detection range θ. The predetermined rotation speed is a speed that is variably controlled by the step-out prevention control means 21d or the step-out prevention control means 21e. The variable control of the speed will be described later.

(2) Step-out allowable control timer 21b
The step-out allowable control timer 21b is a timer that defines the duration of driving of the motor 12 when a step-out occurs, and is a predetermined speed for preventing step-out (in the variable speed range of the needle 11 in this embodiment). The time until the needle 12 whose rotation is controlled at the minimum speed reaches a predetermined position at the speed is set as the timer 21b. The “predetermined position” mentioned here means the upper limit Pe of the detection range θ during the detection operation, and the origin position during the origin return operation. Further, as described above, the timer 21b is also used as a timer for detecting a significant step-out of the stepping motor 12 (a step-out state in which the needle 11 does not rotate).

(3) Detection target presence / absence determination means 21c
The detection target presence / absence determination means (hereinafter referred to as “determination means”) 21c is a means for determining the presence or absence of tool breakage (or workpiece) based on the output of the magnetic encoder 13, and the needle 11 is the upper limit of the detection range θ. When the operation stops beyond Pe (see FIGS. 3A and 3B) or when the needle 11 collides with the tool 1 and stops, a determination process for determining whether or not the tool is broken is performed.

  The determination means 21c detects the stop position of the needle 11 based on the output of the encoder 13, determines whether the needle stop position is within the detection range of the tool based on the information on the stop position and the information on the detection range θ, If it is within the detection range, it is determined that the tool is broken, and if it is outside the detection range, it is determined that the tool is broken. The presence / absence is indicated and the determination result is externally (external device 30 and display unit 24 in this example). Output.

  As shown in FIG. 3, when the control unit 20 detects a tool during the period from the origin position to the detection range, the NG output and the ALM output are turned on, and the information is sent to the control unit 20. To the outside. When a tool is detected at a position that has passed through the detection range, NG output is turned on and the information is output from the control unit 20 to the outside.

(4) Step-out prevention control means 21d
The step-out prevention control means 21d is a means for controlling the operating speed of the needle 11 so that the stepping motor 12 does not step out as much as possible.

  In general, in order to prevent the stepping motor 12 from stepping out, trapezoidal drive (acceleration / deceleration pattern of acceleration / constant speed / deceleration trapezoidal shape) or triangular drive (acceleration / deceleration pattern of acceleration / deceleration triangle shape) is controlled. It has been broken.

  In the present embodiment, the step-out prevention control means 21d performs the following step-out prevention control in addition to the control with the acceleration / deceleration pattern, thereby further preventing the step-out motor from stepping out.

(A) Step-out prevention control during detection operation Before the trapezoidal drive control (trapezoidal or triangular drive control) of the stepping motor 12 during the detection operation, the minimum speed of the variable speed range of the needle 11 is set. Control for operating the needle 11 for a certain time (minimum speed period). In this embodiment, the minimum speed period is calculated from the time until the needle reaches the end point position (the time theoretically obtained from the swing angle and the rotational speed) when there is no step-out, and the trapezoidal or triangular shape. The time obtained by subtracting the drive period of the shape is used.

(B) Step-out prevention control at the time of returning to the origin When the position of the needle 11 is returned to the origin position, the control to operate the needle 11 at the minimum speed in the direction of the origin position.

(5) Step-out allowable control means 21e
The step-out allowable control means 21e is a means for enabling detection of the presence or absence of breakage of the tool even when some step-out occurs. In this embodiment, the step-out motor 12 is out of step. If there is no problem as a tool breakage device even in the generated state, the needle is operated while stepping out.

  The step-out allowable control means 21e performs feedback control that allows some step-out of the stepping motor 12.

  The “slightly out of step” referred to in the present invention means a step out other than a significant step out so that the needle 11 does not rotate even when the stepping motor 12 is driven (so as to be regarded as a collision of the needle 11 with the tool 1). It means that.

  Here, the detection operation when no step-out occurs and the detection operation when the step-out occurs are described with reference to the schematic diagram of FIG.

  In FIG. 4, the vertical axis represents the moving speed of the needle 11 (rotation speed (V) in this example), and the horizontal axis represents the elapsed time (t) from the detection operation start time. The solid line indicates the operation of the needle 11 when no step-out occurs, and the broken line indicates the operation of the needle 11 when the step-out occurs. Further, the “swing angle end point” in FIG. 4 indicates a time point when the needle 11 reaches the end point position of the swing angle when there is no step-out (= time point when the trapezoidal drive control is completed).

  In the present embodiment, in the needle operation control means 21a, the period until the needle 11 reaches the end point position (the swing angle end point) in a state where the stepping motor does not step out is set as the reference drive period of the needle 11. During this period, an excitation pulse is output to the stepping motor 12, and the needle 11 is rotationally controlled with a speed control pattern set according to the type of the tool. At this time, in the present embodiment, the speed control pattern is a speed control pattern in which the needle 11 is operated at a minimum speed for a predetermined time before a predetermined acceleration / deceleration pattern, as indicated by a solid line in FIG.

  Then, when the stepping motor 12 is stepped out and the trapezoidal drive control is completed before reaching the tool detection range upper limit Pe, in other words, the driving of the motor 12 corresponding to the swing angle of the needle 11. At the end of the period ("reference drive period" when there is no step-out), the contact between the needle 11 and the tool 1 is not detected by the determination means 21c (it is not determined that there is no breakage) and When it is determined that the needle 11 has not reached the upper limit of the tool detection range, the step-out allowable control means 21e does not stop the output of the excitation pulse to the stepping motor 12 and the needle 11 is detected by the detection range upper limit Pe ′. The speed at the end of deceleration in trapezoidal driving (the minimum speed of the variable speed range of the needle 11 set corresponding to the type of the tool 1) Continuing issues a command pulse, and to perform the detection process in the detection range limit Pe '.

  The reference drive period is a period (theoretical period) until the needle 11 reaches the end point position, which is the position of the maximum angle within the predetermined angle range, when the motor 12 does not step out. .

  Further, the above-described step-out allowable control timer 21b is provided for a significant step-out time that does not cause the needle 11 to rotate. When the timer 21b times out, the detection operation is stopped and the alarm state is entered. I have to.

  The main operations according to the present invention, such as the processing relating to the above-described step-out permission control, will be described later with reference to flowcharts.

(6) Control information adjusting means 21f
The control information adjusting unit 21f inputs the swing angle (angle range) and rotation speed change information (or one of the change information) of the needle 11 from the operation unit 25, and rotates the needle 11 based on the change information. Means for adjusting control information related to dynamic control (standard setting information such as needle maximum speed, minimum speed, acceleration time, deceleration time, needle swing angle, tool detection range, and step-out allowable control timer value) It is.

  Note that the change information is set using the rotary switch or the like from the operation unit 25 as an example. However, the setting information (change information) may be input from the external device 30. The control information may be stored for each type of tool 1 or each type of needle 11 so that the control information corresponding to the type can be adjusted.

(7) External communication means 21g
The external communication means 21g is a communication means for transmitting / receiving information to / from an external device 30 such as various machine tools or a control device for a tool changer.

  Input of commands from the external device 30 (detection operation start command, command for instructing the needle rotation direction, alarm release command, etc.) and determination result output from the control unit 20 are communicated by the external communication means 21g. Done by control.

  In this embodiment, the external device 30 can obtain the determination result of whether or not the tool is broken only by giving a simple command to the control unit 20 via the external communication means 21g.

  In the configuration as described above, an outline of each operation of the detection apparatus according to the present invention, details of processing in each operation, and step-out prevention and step-out allowable control will be described. Hereinafter, the processing that has already been described will be omitted or simplified.

  First, the outline of each operation of the detection apparatus will be described with reference to the flowchart of FIG. Here, an outline of the basic operation of the apparatus will be described, and details of the processing of each step (S1 to S6) in FIG. 5 will be described later.

  When a reverse command is input after the detection device is turned on (step S1), the control unit 21 of the control unit executes the origin return processing (A) of the needle 11. This origin return process (A) is a process for performing an operation (origin return operation) for rotating the needle 11 to the position of the origin by the drive control of the stepping motor 12 (origin return operation). This is also executed when the needle 11 is out of the origin position or after the alarm is released (step S2).

  When the return to origin operation of the needle 11 in step S2 is completed, the control unit 21 waits for a command to start a tool breakage detection operation after a certain period of time to prevent step-out (step S3). In this state, when a detection operation start command is input from the external device 30 (or the operation unit 25), the control unit 21 of the control unit 20 determines the period until the needle 11 reaches the end point of the swing angle. As an output period (T), during the output period (T), a command pulse is output to the stepping motor 12 to rotate the needle 11 (step S4).

  Then, after stopping the output of the command pulse, or when determining that the needle 11 has collided with the tool 1 during the output of the command pulse, the control unit 21 stops the needle 11 (moving position from the origin position). Is detected based on the output of the magnetic encoder 13, and the presence or absence of breakage of the tool 1 is determined by determining whether or not the detected stop position is within the detection range, and the determination result is transmitted via the external communication means 21g. Are output to the external device 30 and displayed on the display unit 24 (step S5).

  Then, the control part 21 performs the origin return process (B) of the needle 11 (step S6). The origin return process (B) in step S6 is a process for executing an operation of moving the needle 11 to the position of the origin after the detection operation. Compared to the origin return process (A) in step S2, a step-out described later is performed. The speed control related to prevention control is different from the control related to overrun.

  When the return-to-origin operation of the needle 11 in step S6 is completed, the control unit 21 proceeds to step S3 and waits for the start of the detection operation for the next tool.

  Next, details of the processing in steps S2 to S6 in FIG. 5 and step-out prevention and step-out allowance control will be described. Here, characteristic operation control of the detection apparatus according to the present invention will be mainly described.

<< 1 >> Origin Return Process (A) (Step S2)
The origin return process (A) is a process for executing an operation (origin return operation) for moving the needle 11 to the origin position as described above. This origin return operation is performed by a backward command immediately after the power is turned on. Executed when entered. In addition, when the needle 11 is out of the origin position in the standby state, or when the origin is returned after the alarm is released, this origin return operation is executed.

  FIG. 6 is a flowchart for explaining the processing executed in the control unit 20, and the origin return processing (A) will be explained along the flow of FIG.

  Immediately after the power is turned on, the motor 12 is not excited and the position of the needle 11 is in a free state.

  When the reverse command input is turned on (step S2-1), the control unit 20 activates the step-out allowable control timer 21b (T1) (step S2-2) and starts the origin return operation of the needle 11.

  At that time, the control unit 20 (the step-out prevention control means 21d of the control unit 21) moves the needle 11 to the position of the origin at a predetermined speed for step-out prevention in order to reduce the elements caused by the step-out ( Step S2-3).

  The step-out prevention speed is the lowest speed in the variable speed range of the needle 11. The minimum speed is a speed based on a command pulse equal to or lower than the self-start frequency (the frequency of the command pulse that can be started without being stepped out) in the current load of the stepping motor 12. In other words, the control unit generates a command pulse corresponding to the speed of the rotor of the stepping motor 11 corresponding to the minimum speed by setting the speed at which the rotation of the needle 11 does not stop as the minimum speed. Drive control is performed.

  In step S2-2, step-out detection processing of the stepping motor 12 is compared. More specifically, the command pulse and the feedback pulse from the encoder 13 are compared, and if the difference is large, the motor 12 is regarded as step-out. In the slight step-out state (the state that does not synchronize with the command but rotates), the needle 1 is made to reach the position of the origin anyway.

  In other words, there are few requests to shorten the cycle time immediately after the power is turned on or when an alarm is generated, and it may take time. In the origin return process (A), the minimum speed is required to complete the origin return reliably. Thus, the processing mode for operating the needle 11 is adopted.

  Here, the step-out of the stepping motor 12 will be described.

  There is a step in the step-out, and if it is a slight step-out, it rotates without being synchronized with the command. As the symptom of step-out increases, the amount of rotation with respect to the command decreases and eventually stops rotating.

  Therefore, in the present embodiment, a step-out allowable control timer 21b (T1) is provided for a case where the step-out is significant enough not to rotate, and the return to the home position is performed within the time of the timer 21b (T1). It is determined whether or not the process has been completed (step S2-4). If it is determined that the timer 21b (T1) has timed out without being completed, the process shifts to an alarm state (process of step S7 described later).

  On the other hand, if it is determined in step S2-4 that the return to the origin position has been completed, the origin position output of the display unit 24 is turned on and a standby state is entered (step S2-5).

<< 2 >> Standby process (step S3)
The standby process is a process executed in the control unit 20 in a standby state (waiting for a tool breakage detection operation start command), after completion of the origin return operation of the needle 11 by the origin return process (A), or the origin This waiting process is executed after the completion of the origin returning operation of the needle 11 by the returning process (B).

  FIGS. 7A and 7B are flowcharts for explaining the processing in the standby state, and the standby processing will be described along the flow of FIG.

  The standby state is a state of waiting for a command for starting the tool breakage detection operation, and the state shifts to this state after the return to origin (A) of the needle 11 is completed or after the return to origin (B) is completed.

  The waiting process includes a waiting process (hereinafter referred to as “standby process 1”) for avoiding the step-out of the motor 12 caused by vibration at the time of return of the needle 11 to the origin, and a needle caused by a waiting disturbance or the like. 11 is a standby process (hereinafter referred to as “standby process 2”) for adjusting the deviation from the origin position to match the origin position.

  First, the standby process 1 will be described along the flow of the flowchart of FIG.

  The control unit 20 activates the step-out prevention control timer 21b (T0) (step S3-1), waits for a tool breakage detection start command (step S3-2), and then sends a start command from the external device 30. It is determined whether or not an input has been made (step S3-3). If it is determined that the input has been made within the time of the timer 21b (T0), the standby state is continued without accepting the start command (step S3-4). .

  On the other hand, if it is determined in step S3-3 that the start command has been input after the time of the timer 21b (T0), the process proceeds to step S4, where the needle 11 is operated to start the detection operation.

  That is, the control unit 20 does not operate the motor 12 by not accepting a detection operation start command for a certain period of time after entering the standby state. This is because immediately after the needle 11 returns to the standby position, the vibration of the needle 11 is large, and when the next operation is started in this state, the torque of the motor 12 is insufficient and a step-out occurs.

  In other words, since the vibration of the needle 11 is reduced with the passage of time, the control unit 20 reduces the risk of step-out by taking time between the completion of the return to origin and the next detection operation. .

  Next, the standby process 2 will be described along the flow of the flowchart of FIG.

  The control unit 20 determines whether or not the needle 11 is at the origin position during standby (step S3-5). If it is determined that the needle 11 is not at the origin position, the needle 11 is moved to the origin due to disturbance or the like during standby. It is determined that the sensor 14 has deviated from the position of the sensor 14, and the origin position output of the display unit 24 is turned off, and the process proceeds to step S2 to execute the origin return process (A) of the needle 11.

  Then, if the needle 11 does not return to the origin position for some reason, it shifts to an alarm state (processing in step S7 described later) due to timeout.

<< 3 >> Detection Operation (Step S4)
As described above, when a detection operation start command is input after a predetermined time has elapsed since entering the standby state (when the forward command input is turned on), the operation shifts to a tool breakage detection operation.

  FIG. 8 is a flowchart for explaining the process related to the detection operation, and the tool breakage detection process will be described along the flow of FIG.

  The control unit 20 outputs a command pulse to the stepping motor 12 to start the rotation operation of the needle 11. Then, when the needle 11 is removed from the position of the origin sensor 14, the origin position output is turned off.

  In this embodiment, when the forward command input is turned on, the control unit 20 activates the step-out allowable control timer 21b (T2) (step S4-1), and the direction of the detection range by the initial drive command pulse. The needle 11 is operated at the minimum speed for a certain time. This is to remove the step-out factor at the start-up such as the vibration of the needle 11 at the origin position (step S4-2).

  Then, after the operation at the minimum speed for a certain time is completed, the needle 11 is moved in the direction of the detection range by a predetermined acceleration / deceleration pattern. The acceleration / deceleration pattern is an acceleration / deceleration pattern based on the set acceleration / deceleration time and maximum speed, and the movement speed (rotational speed in this example) of the needle 11 corresponding to the angular speed of the motor 12 is determined by so-called trapezoidal driving. Control (step S4-3).

  The trapezoidal driving (acceleration / constant speed / deceleration trapezoidal speed pattern) in step S4-3 may be triangular driving depending on conditions such as the swing angle of the needle 11 and the rotational speed.

  The purpose of trapezoidal drive is to reduce the risk of step-out by setting an appropriate acceleration / deceleration time, and the above trapezoidal drive is one of the common driving methods of stepping motors, and specific drive control Will not be described.

  Here, before explaining the processing after step S4-3, conditions for shifting to the determination of the presence / absence of a tool (step S5) will be explained.

  When step-out does not occur and the needle 11 does not collide with the tool, the needle 11 is moved at the timing when the command pulse is stopped and the motor 12 is stopped according to the end of the deceleration period of the trapezoidal drive. Since there is no tool ahead of the upper limit of the detection range because it is at the end point position of the swing angle (rotation angle) (in this example, the position of the maximum angle of the predetermined angle range including the fan-shaped detection range), it is determined whether or not there is a tool Can be migrated to.

  However, when step-out occurs, the rotation amount of the motor 12 is less than expected, and the needle 11 may not reach the upper limit of the detection range even after the trapezoidal drive deceleration period ends.

  In that case, since there is a possibility that a tool exists between the position after the end of the trapezoidal drive and the upper limit of the detection range, in this embodiment, before stepping out and reaching the upper limit of the detection range, the trapezoid When the driving is completed, the speed at the end of the trapezoidal drive deceleration (the variable speed of the needle 11) is detected until the contact between the needle 11 and the tool 1 is detected or until the needle 11 reaches the upper limit of the detection range. In this mode, the control (referred to as “step-out allowable control”) that continuously outputs the command pulse at the lowest speed in the range is performed. That is, similarly to the step-out allowance control in the origin return process (A), the speed at which the rotation of the needle 11 does not stop is set as the minimum speed, and the control unit uses the speed of the rotor of the stepping motor 11 corresponding to the minimum speed. A command pulse corresponding to the above is generated and the drive control of the stepping motor 11 is performed. When the upper limit of the detection range is reached within the time of the step-out allowable control timer 21b (T2), the command pulse is stopped and the process proceeds to the determination of the presence / absence of the tool.

  As a result, an operation that allows a slight step-out that is not a significant step-out so that the needle 11 does not rotate (so as to be regarded as a collision) is realized.

  By performing the step-out allowance control as described above, the needle 11 almost reaches the upper limit of the detection range even when some step-out occurs. At that time, when the tool is present up to the upper limit of the detection range and the needle 11 collides with the tool, the needle 11 is stopped, the feedback pulse from the encoder 13 is stopped, and the rotation of the needle is stopped. Since it can be detected that it has stopped, the presence or absence of a tool can be determined from this fact. That is, by the above-described step-out allowance control, even when the needle 11 is stopped due to a collision with the tool, the determination of the presence / absence of the tool is made.

  Therefore, the conditions for shifting to the presence / absence determination of the tool are two conditions, that is, the needle 11 stops exceeding the upper limit of the detection range, or the needle 11 collides with the tool and stops.

  Processing related to the above-described step-out permission control will be described along the flow of FIG. 8 (step S4-4 and subsequent steps).

  While executing the process of step S4-3 (trapezoidal or triangular drive control), the control unit 20 detects whether the needle 11 has stopped based on the output (feedback pulse) of the encoder 13. (Steps S4-4, S4-5). And when a feedback pulse stops, it determines with the needle 11 having stopped, and after stopping a command pulse, it transfers to determination of a tool presence (step S5) (step S4-6).

  On the other hand, if it is determined in step S4-5 that the needle 11 has not stopped, the current position of the needle 11 is detected based on the output of the encoder 13 (step S4-7), and the needle 11 reaches the upper limit of the detection range. It is determined whether or not it has been reached (step S4-8).

  And when it determines with the needle 11 having reached the upper limit of the detection range, after stopping a command pulse, it transfers to determination of a tool presence or absence (step S4-9).

  On the other hand, if it is determined in step S4-8 that the needle 11 has not reached the upper limit of the detection range, it is determined whether or not a timeout of the step-out allowable control timer 21b (T2) has occurred (step S4). -10). If no time-out has occurred, drive control at the minimum speed by the command pulse for step-out allowable control, for example, the command pulse is continuously output at the speed at the end of deceleration of the trapezoidal drive (step S4-11), step The processes after S4-4 are repeated.

  On the other hand, if it is determined in step S4-10 that the time-out of the step-out allowable control timer 21b (T2) has occurred, it is determined that a significant step-out has occurred so that the needle 11 does not rotate, and the command pulse Is stopped (step S4-12), and then the state shifts to an alarm state (step S7 described later).

<< 4 >> Judgment processing for tool breakage (step S5)
After executing the detection operation, the control unit 20 determines whether or not the tool is broken based on the position where the needle 11 is stopped.

  FIG. 9 is a flowchart for explaining the determination processing, and the determination processing for the presence or absence of tool breakage will be described along the flow of FIG.

  The control unit 20 detects the stop position of the needle 11 based on the feedback pulse from the encoder 13 (step S5-1), and determines whether the stop position of the needle 11 is within the detection range (step S5-2). . If the stop position is determined to be within the detection range, it is determined that the needle 11 has collided with the tool and stopped, and a determination result indicating tool breakage “none” is output to the external device 30 and the display unit 24. OK or NG determination output is turned on (steps S5-4, S5-5).

  On the other hand, if it is determined in step S5-2 that the stop position is outside the detection range (a position exceeding the upper limit of the detection range), a determination result indicating tool breakage “present” is output to the external device 30, and the display unit 24 OK or NG judgment output is turned on (steps S5-3, S5-5).

  And after outputting a determination result, after progress for a fixed time (step S5-6), it transfers to an origin return process (B).

  In step S5-6, the reason for waiting for a certain time to elapse is to prevent the start-up torque of the motor 12 from increasing due to the vibration of the needle 11 caused by the impact when the needle is stopped.

<< 5 >> Origin Return Process (B) (Step S6)
The control unit 20 shifts to the home position return process (B) automatically or according to the setting of the operation unit 25 after the completion of the tool breakage determination process or when the reverse command input is turned on.

  FIG. 10 is a flowchart for explaining the origin return process. The origin return process (B) of the needle 11 will be described with reference to FIG.

  In the control unit 20, at the start of the home position return operation (B), the step-out allowable control timer 21b (T3) is activated (step S6-1), and the needle 11 is moved toward the home position at a minimum speed for a certain time. Move (step S6-2).

  In step S6-2, the reason why the needle 11 is operated at the minimum speed for a certain period of time is to remove a step-out factor at the start-up such as the vibration of the needle when the needle is stopped.

  In the above-described origin return processing (A), the needle 11 is always operated at the lowest speed. However, the origin return operation (B) is an operation related to the cycle time, so that the operation time should be shorter. Therefore, in the origin return process (B), after the initial operation of origin return, the needle 11 is operated with a predetermined speed control pattern including acceleration / deceleration by trapezoidal drive (trapezoidal or triangular drive control). (Step S6-3).

  In the return to origin process (B), if the command pulse is completed before the needle 11 reaches the origin position (position of the origin sensor 14) due to step-out, the deceleration ends until the origin position is reached. The command pulse is continuously output at a speed of. This is to ensure that the needle 11 reaches the origin even if it is out of step (steps S6-4 to S6-7).

  In the present embodiment, a timer 21b (T3) is provided for a significant step-out time that does not rotate, and the step-out allowable control timer 21b (T3) set in step S6-1 times out. (Step S6-4, step S6-8), and when a time-out occurs, the alarm state is entered.

  By the way, step out includes step out which does not follow the command pulse and step out (overrun) which cannot be stopped even if the command pulse stops. In the present embodiment, in order to cope with the latter overrun, the control unit 20 rotates the needle 11 until it passes the position of the origin sensor 14 (steps S6-5 to S6-7), Thereafter, the needle 11 is reversed in the forward direction (step S6-9), and in step S6-10, the origin position output is turned on when the position exceeding the origin sensor 14 is reached, and the origin return operation is completed. Then, after completion of the origin return process (B), the process shifts to a standby state.

<< 6 >> Alarm State During each operation, the control unit 20 shifts to an alarm state due to the timeout of the timer 21b (T1 to T3) described above.

  FIG. 11 is a flowchart for explaining the processing in the alarm state. In the alarm state, the control unit 20 stops the excitation of the motor 12 to make it free (step S7-1), and turns on the alarm output. In addition, alarm information indicating the occurrence of an abnormality (in this example, the occurrence of significant motor out-of-step) is output to the external device 30 via the external communication means 21g and displayed on the display unit 24 of the control unit 20. The alarm information includes types such as out of detection range, overload, timeout, overcurrent, overtemperature, and the like (step S7-2).

  Then, the alarm output is turned off by the input of the alarm release command from the external device 30 (step S7-3). At that time, the motor 11 remains in a free state, and when the reverse command input from the external device 30 is turned on with the alarm output turned off by the input of the alarm release command (step S7-3), the origin return process is performed. Move to (A).

1 Tool (or workpiece)
DESCRIPTION OF SYMBOLS 10 Sensing head 10a Attachment 11 Needle 11a Needle cap 12 Actuator (stepping motor)
12a Rotating shaft 13 Position detection sensor (magnetic encoder)
14 Origin sensor (photo sensor)
15 Input / output unit 15a Information transmission means (cable)
20 Control unit 21 Control unit 21a Needle operation control means 21b Step out permission control timer 21c Detection target presence / absence determination means 21d Step out prevention control means 21e Step out permission control means 21f Control information adjustment means 21g External communication means 22 Input / output section 23 Storage unit 24 Display unit (Monitor LED)
25 Operation unit 30 External device

Claims (7)

A breakage of a tool for machining a workpiece, or a sensing head for detecting the presence or absence of the detection target as a detection target, and a detection that controls the operation of the sensing head and indicates the presence or absence of the detection target A control unit having a function of outputting a result to an external device, and a tool breakage or workpiece detection device comprising:
The sensing head is
A contact-type detector that is rotatable within a predetermined angle range from an origin position to an end position including a fan-shaped detection range, a stepping motor as an actuator that drives the detector to rotate, and the current position of the detector A magnetic encoder as a sensor for detecting the position and a photo sensor for detecting the origin position,
The control unit is
A control unit for controlling the rotation of the detector by feedback control of the stepping motor and controlling communication with the external device;
The controller is
Control for controlling rotation of the detector in a predetermined acceleration / deceleration pattern, with the period until the detector reaches the end point in a state where the stepping motor is not out of step as a reference drive period of the detector Means,
Determining means for determining whether or not the detection target exists by detecting whether or not the detector and the tool or the workpiece are in contact with each other within the reference driving period, based on the output of the magnetic encoder;
When it is determined by the determination means that contact between the detector and the tool or the workpiece has not been detected and the detector has not reached the upper limit of the detection range within the reference drive period, Without stopping the output of the excitation pulse to the stepping motor at the time when the reference drive period has elapsed, the excitation pulse is continuously output until the detector reaches the upper limit of the detection range, and the determination process by the determination unit is continued. And a tool for detecting breakage of a tool, or a workpiece detection device, comprising: a step-out allowable control means for performing control.   The excitation pulse that the step-out allowable control means continues to output after the elapse of the reference drive period is an excitation pulse for step-out allowable control that rotates the detector at the lowest speed in the variable speed range of the detector. The step-out allowable control means outputs the excitation pulse to the stepping motor until contact between the detector and the tool or the workpiece is detected or until the detector reaches the upper limit of the detection range. The tool breakage or workpiece detection device according to claim 1, wherein the tool breakage or workpiece detection device is continued.   A step-out allowable control timer that defines the duration of driving of the stepping motor when the step-out occurs is provided, and the control means is configured so that the detector and the tool or the workpiece are not in contact with each other. If the step-out allowable control timer times out, it is determined that a significant step-out has occurred so that the detector does not rotate, and the output of the excitation pulse is stopped and alarm information indicating the occurrence of an abnormality is displayed. The tool breakage or workpiece detection device according to claim 1, wherein the breakage is output to the external device.   Before the rotation control with the predetermined acceleration / deceleration pattern, the stepping motor is prevented from being stepped out by performing a control for rotating the detector for a predetermined time at the lowest speed of the variable speed range of the detector. 4. The tool breakage or workpiece detection device according to claim 1, further comprising step-out prevention control means for performing the step-out prevention.   The step-out prevention control means performs control to rotate the detector at a minimum speed in a variable speed range of the detector when returning the position of the detector to the origin position. The tool breakage or workpiece detection apparatus according to claim 4.   The step-out prevention control unit performs control so that the stepping motor is not operated for a certain period after the detection operation by the detector is set in a standby state and after determination of the presence or absence of the detection target. 4. Tool breakage or workpiece detection device according to 4 or 5.   The control unit inputs, as setting information from the operation unit or the external device, an angle range from the origin position to the end position and change information of the rotation speed of the detector, or any one change information, The tool breakage or workpiece according to any one of claims 1 to 6, further comprising control information adjusting means for adjusting control information related to rotation control of the detector based on input change information. Detection device.