WO2023053436A1

WO2023053436A1 - Workpiece seating detection device

Info

Publication number: WO2023053436A1
Application number: PCT/JP2021/036374
Authority: WO
Inventors: 伊藤昌治; 野々口哲輝; 山口徹; 福岡大祐
Original assignee: 株式会社Fuji
Priority date: 2021-10-01
Filing date: 2021-10-01
Publication date: 2023-04-06
Also published as: JPWO2023053436A1

Abstract

Provided is a workpiece seating detection device in which piping length is reduced, the workpiece seating detection device having: a detection orifice through which air is discharged from a seating surface of a chuck for grasping a workpiece; an air supply flow path for sending air from an air supply source to the detection orifice; a pressure control valve provided to the air supply flow path; a seating sensor provided to the air supply flow path at a location on the secondary side of the pressure control valve; a relay device for transmitting measurement data measured by the seating sensor; and a control device for calculating a threshold value for assessing seating on the basis of display, on an operation display device, of the measurement data acquired via the relay device, and the operation of the operation display device.

Description

Workpiece seating detection device

The present invention relates to a workpiece seating detection device for determining seating of a workpiece gripped by a spindle chuck.

In machine tools such as lathes, the workpiece is gripped by the spindle chuck, and cutting is performed by applying the cutting tool to the workpiece as the spindle rotates. At that time, if the work is not accurately in contact with the seating surface of the spindle chuck, the work will be cut off excessively, resulting in a reduction in finishing quality. Therefore, a machine tool is provided with a workpiece seating detection device so that it can be determined whether or not the workpiece is properly in contact with the seating surface of the spindle chuck. Specifically, an open detection hole is formed in the seating surface of the spindle chuck, and air is sent into the hole from an air supply source. The workpiece gripped by the spindle chuck is brought into contact with the seating surface and closes the detection hole, but a slight gap is generated and a certain amount of air leaks, so seating determination is made according to the amount of leakage.

In the workpiece seating detection device described in Patent Document 1 below, when the workpiece is pressed against the seating surface of the unclamped chuck, the seating sensor is turned on in the correct seating state, and the control device cancels the clamping disapproval. be. In response to this release, a clamp command is output and the chuck is clamped. Once the chuck is properly seated and the clamping operation is started, if the seating failure occurs after that, the seating sensor is turned off, the clamping command is stopped, and the clamping operation of the chuck is interrupted.

JP 2004-142077 A

When workpieces are machined repeatedly by a machine tool, the seating surface of the workpiece seating detection device becomes dirty with chips and coolant that scatters. put away. It is indispensable for the workpiece seating detection device to periodically adjust the threshold value for seating determination so as to correspond to the change. Threshold adjustment is performed while the master work is in close contact with the metal of the spindle chuck. To make the work easier for the operator, the seating sensor is attached to a position away from the spindle chuck, such as on the front of the fuselage. Therefore, in the conventional workpiece seating detection device, the piping for flowing air through the seating sensor to the spindle chuck is long, and it takes time to pressurize, resulting in a long work time required for threshold adjustment.

Therefore, in order to solve this problem, an object of the present invention is to provide a workpiece seating detection device with a short pipe length.

A workpiece seating detection device according to one aspect of the present invention includes a detection hole for discharging air from a seating surface of a chuck that grips a workpiece, and an air supply flow for sending air from an air supply source to the detection hole. a pressure control valve provided in the air supply channel; a seating sensor provided in the air supply channel on the secondary side of the pressure control valve; and measurement data measured by the seating sensor. and a control device that displays the measurement data acquired via the relay device on an operation display device and calculates a threshold value for seat determination based on the operation of the operation display device. .

According to the above configuration, the air from the air supply source flows through the air supply channel, is sent to the detection hole formed in the seating surface of the chuck that grips the workpiece, and is provided on the secondary side of the pressure control valve. Measurement data measured by the seat sensor is transmitted to the control device via the relay device. The measurement data is displayed on the operation display device, and based on the display, it becomes possible to calculate a threshold value for seating determination by operating the operation display device. Therefore, it is not necessary to place the seating sensor at a position far from the seating surface, and the air supply passage of the workpiece seating detection device can be shortened. can shorten the time required to reach a state where

1 is a side view showing an internal structure of a machine tool equipped with a workpiece seating detection device; FIG. 1 is a simplified diagram showing an embodiment of a workpiece seating detection device; FIG. It is the figure which showed the seating surface of the spindle chuck. It is a block diagram showing the control system of a machine tool. It is the figure which showed the operation screen of the operation display device which makes a flow volume change into a graph and displays it. FIG. 7 is a diagram showing changes in flow rate due to seating failure that can occur during workpiece machining. It is a diagram showing the state of the air pipe in the conventional workpiece seating detection device.

An embodiment of a workpiece seating detection device according to the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing the internal structure of a machine tool equipped with a workpiece seating detection device according to this embodiment. A machine tool 1 is mounted on a movable bed 2 equipped with wheels, and is movable in the front-rear direction (Z-axis direction) along rails laid on a base 3 . The machine tool 1 has a tool rest 11 having rotary tools such as end mills and drills, or cutting tools such as cutting tools.

A machine tool 1 has a spindle device 5 mounted on a movable bed 2, and has a structure in which a spindle chuck 12 that grips a workpiece can rotate. The machine tool 1 is a two-axis lathe in which a turret device 4 is moved by a Z-axis drive device 6 that moves in the Z-axis direction parallel to the main shaft and an X-axis drive device 7 that moves in the X-axis direction, which is the vertical direction of the machine body. be. The Z-axis driving device 6 and the X-axis driving device 7 have a slidable Z-axis slide 13 or X-axis slide 14, and are configured to convert the rotation output of the servomotor into linear motion by a ball screw mechanism.

In addition to the body cover 15 that constitutes the machining chamber 10, the machine tool 1 is provided with an openable and closable front cover 16 on the front face of the machine body. The machine tool 1 is modularized in the same manner as other work machines that constitute a processing machine line, and a plurality of front covers 16 are arranged in the width direction of the machine body to form a work transfer space 20 . In the work transfer space 20, an automatic work transfer machine for transferring the work W to each working machine is incorporated.

The machine tool 1 is provided with a workpiece seating detection device that determines whether or not the workpiece W is properly gripped when the spindle chuck 12 receives the workpiece W. FIG. 2 is a diagram showing a simplified configuration of the workpiece seating detection device 17 provided in the machine tool 1. As shown in FIG. The workpiece seating detection device 17 has three detection holes 22 formed in a seating surface 21 of the spindle chuck 12 (see FIG. 3). An air supply source 24 such as a compressor is connected to the detection hole 22 via an air pipe 23, and an electromagnetic on-off valve 25, a pressure control valve 26 and a seating sensor 27 are connected to the air pipe 23 in order toward the downstream side. It is

The workpiece seating detection device 17 is configured such that air sent from an air supply source 24 to an air pipe 23 flows into the spindle chuck 12 at a predetermined pressure, and the air is discharged from the detection hole 22 in the unclamped state. Become. On the other hand, when the workpiece W is transferred to the spindle chuck 12 by the workpiece transfer robot, the detection hole 22 is blocked and the air flow is interrupted. However, the workpiece W does not come into close contact with the seating surface 21 and the detection hole 22 is not completely blocked, and a small amount of air leaks through a slight gap. The seating sensor 27 of the present embodiment is a flow rate sensor that measures the flow rate of air flowing out from the detection hole 22, and is referred to as a flow rate sensor 27 in the following description.

The workpiece seating detection device 17 is configured such that the measured value by the flow sensor 27 is transmitted to the control device 9 and the seating determination is performed by comparing it with a preset threshold value. A master work MW that creates a predetermined gap in the seating surface 21 of the spindle chuck 12 is used to set such a threshold. FIG. 3 is a view showing the seating surface of the spindle chuck 12. As shown in FIG. The master work MW is gripped by the chuck claws while being centered on the seating surface 21 as indicated by the dashed line. The master work MW has a disc-shaped center with a hole 31, and a first adjustment groove 33 extending radially from the center hole 31 to the outer diameter end at a position separated by 180 degrees on one end face in the axial direction. A second adjustment groove 34 is formed.

The first adjustment groove 33 is a shallow OK groove that creates an allowable clearance when the work is seated, and the second adjustment groove 34 is a deep NG groove that creates a clearance that is determined to be a seating error. A seating surface 21 of the spindle chuck 12 has three detection holes 22 on the same circumference at intervals of 120 degrees. In the threshold value setting operation, the phase of the master work MW is determined so that the first adjusting groove 33 and the second adjusting groove 34 overlap each detection hole 22 in order.

　The threshold, which is the basis for seating determination, is set not only at the initial stage but also periodically. This is because when the machining of the workpiece is repeated in the machine tool 1, chips and coolant that scatter in the machining chamber also adhere to the detection hole 22 of the spindle chuck 12 and interfere with the air flow, resulting in a change in the amount of air leakage. be. Even in such a situation, it is necessary to stably and accurately determine seating, and it is necessary to periodically reset the threshold according to changes in the amount of leakage.

The machine tool 1 has a short dimension in the width direction of the machine body, but the distance in the same direction is long due to the arrangement of the turret device 4 and the spindle device 5 in the longitudinal direction of the machine body. The workpiece seating detection device 17 is provided on the rear side of the spindle device 5 . On the other hand, it is necessary to set the threshold value in the workpiece seating detection device 17 while checking the measurement value of the flow sensor 27, which is extremely difficult if the flow sensor 27 is arranged at the back of the fuselage.

Therefore, in the conventional workpiece seating detection device 100, the flow rate sensor 105 is installed on the front upper part of the machine tool 1 as shown in FIG. This arrangement allows the operator to easily see the measured value of the flow rate sensor 105 . However, in the conventional workpiece seating detection device 100, the air pipe 110 had to pass through the ceiling of the cover from the rear part of the machine body to the front part, and the pipe length exceeded 6 m. Therefore, it takes time for the inside of the air pipe 110 to pressurize and the state to stabilize, and it takes a long time to obtain an appropriate measurement value of the flow sensor 105 and set the threshold value.

Therefore, the work seating detection device 17 of this embodiment is configured so that the measurement data can be obtained by the control device 9 without directly checking the flow rate sensor 27 . Here, FIG. 4 is a block diagram showing the control system of the machine tool 1. As shown in FIG. The control device 9 is mainly composed of a computer having storage devices such as a ROM 52, a RAM 53, and a non-volatile memory 54 in addition to the CPU 51. It is connected to each drive unit such as the device 6 , the X-axis drive device 7 and the workpiece seating detection device 17 .

The machine tool 1 has a touch panel type operation display device 18 attached to the front of the machine body, which displays work information, an operation screen, etc., and allows the operator to input setting values. there is In this embodiment, the measurement data of the flow rate sensor 27 is displayed on the operation display device 18 via the control device 9, and in addition, the threshold value can be set from the operation display device 18. FIG. That is, the flow rate sensor 27 of the workpiece seating detection device 17 is connected to the control device 9 via the relay device 28 .

The flow sensor 27 is, for example, a Karman vortex flow meter, outputs an analog signal in response to vibration transmitted from the pressure receiving portion acting on the Karman vortex to the piezoelectric element, and the sensor substrate converts the analog signal into a digital signal. It is configured to detect the frequency of the digital signal and digitize the flow rate. For example, IO-Link (registered trademark) is used as communication means for capturing the measurement data of the flow rate sensor 27, and the relay device 28 is an IO-Link master that performs point-to-point communication with the IO-Link device.

Threshold setting for seating determination is performed by causing the spindle chuck 12 to grip the master work MW. The setting input of the threshold is possible from the display device 18 . In threshold setting, first, the master work MW is gripped by the spindle chuck 12 while changing the phase so that the first adjusting groove 33 and the second adjusting groove 34 are overlapped with the three detection holes 22 in order. Of the detection holes 22 into which air is constantly fed, air leaks from one of the detection holes 22 due to the first adjustment groove 33 or the second adjustment groove 34, and the openings of the remaining two detection holes 22 are blocked. In this state, the flow rate sensor 27 measures the amount of air leaking out from one detection hole 22 , and the measurement data is sent to the control device 9 via the relay device 28 .

The measured value of the flow rate sensor 27 taken into the control device 9 is stored in the storage unit of the control device 9 as measured flow rate data at the time of measurement, and is also displayed on the operation display device 18 installed on the front of the aircraft. For example, as shown in FIG. 5, the change in flow rate is represented as a graph on the operation screen 37 of the operation display device 18 . This graph shows flow values measured by the flow sensor 27 and moves to the right as the measurement time elapses. The flow rate is displayed on the vertical axis, and the horizontal axis indicating the measurement time switches between hours and minutes from T1 to T6 as the graph moves along with the passage of time. At the top of the graph display area 41, the measured value at the current time of T6 is displayed in a flow rate display box 42. FIG.

The first adjusting groove 33 and the second adjusting groove 34 are sequentially overlapped with the three detection holes 22, and the respective leakage amounts are measured by the first adjusting groove 33, OK1, OK2, and OK3, and the second adjusting groove The measured values NG1, NG2, and NG3 by 34 are stored in the storage unit. Specifically, the operator confirms the flow rate while looking at the graph shown in FIG. Measured value capture buttons include an OK measurement button 43 and an NG measurement button 44, and the averaged flow rate measurement values for several seconds before or at the time each button is pressed are stored as the measurement value OK1, for example, measured by the first adjusting groove 33. It is designed to be

The measured values obtained by the operator are displayed in the measured value box 46 provided on the operation screen 37 in order according to the operation of the OK measurement button 43 and the NG measurement button 44. After each measured value is obtained, the operator presses the threshold setting button 45 to automatically calculate the threshold based on the following equation. The threshold value TH is the average value of the leakage amount in the OK groove and the NG groove of the three detection holes 22, OKa = (OK1 + OK2 + OK3) / 3, NGa = (NG1 + NG2 + NG3) / 3, the threshold is TH = OKa + (NGa + OKa )/2. That is, the threshold value TH is set to an intermediate value between the leak amounts in the NG groove and the OK groove.

In the workpiece seating detection device 17 of this embodiment, the flow rate value measured by the flow rate sensor 27 is sent to the control device 9 via the relay device 28 and displayed on the operation display device 18 attached to the front surface of the machine body. Therefore, the workpiece seating detection device 17 does not need to attach the flow rate sensor 27 to the front surface of the machine tool 1, and can be arranged behind the spindle device 5 so that the operator can easily check it. Therefore, the air pipe 23 of the workpiece seating detection device 17 can be shortened, and the time from when the master work MW is seated to when the pressure in the air pipe 23 rises and seating can be determined can be shortened. can.

The workpiece seating detection device 17 displays the current value measured by the flow rate sensor 27 on the operation display device 18 in the flow rate display box 42, and in particular, the change in the flow rate over time is shown graphically as shown in FIG. Therefore, the operator can grasp the seating state of the workpiece during machining in the machine tool 1 from such information. Therefore, in the workpiece seating detection device 17 of the present embodiment, as shown in FIG. It is configured to determine the situation in which the workpiece W is gripped.

The first threshold value S1 is for detecting an increase in air leakage flow rate when the workpiece W slightly moves in the spindle chuck 12 . The second threshold value S2 is for detecting an increase in the air leakage flow rate when the workpiece W is detached from the spindle chuck 12 . Therefore, during the machining of the workpiece W starting at T7, the measured value of the flow rate sensor 27 would normally be a value near the flow rate R1. However, when the workpiece W is displaced or dropped, the measured values increase to the flow rates R2 and R3. Therefore, if the measured value of the flow rate sensor 27 exceeds the first or second threshold values S1, S2 during work clamping during work machining, the controller 9 stops driving the machine tool 1. Then, a warning display or alarm is issued on the operation display device 18 .

Therefore, according to the present embodiment, it is possible to arbitrarily set a threshold value and perform predetermined drive control for the machine tool 1 based on the value. Then, as described above, the clamping state during machining can be determined by the first and second threshold values S1 and S2. In addition, the work seating detection device 17 can store the flow rate value for each time measured by the flow rate sensor 27 in the storage section of the control device 9 as work chuck information. Therefore, a graph such as that shown in FIG. 5 can be reproduced retroactively, and can be used as one piece of information for investigating the cause when a problem occurs in the machining of a workpiece.

Although one embodiment of the present invention has been described, the present invention is not limited to this, and various modifications can be made without departing from the scope of the invention.
For example, a flow rate sensor is used as the seating sensor, and IO-Link (registered trademark) is used as a communication means for capturing the measurement data of the seating sensor, but the workpiece seating detection device of the present invention is not limited thereto.
In the above-described embodiment, the measured value of the flow rate over time is graphed and displayed on the operation screen of the operation display device 18. However, the flow rate may be displayed as a numerical value together with the measurement time. may

DESCRIPTION OF SYMBOLS 1... Machine tool 5... Spindle device 9... Control device 12... Spindle chuck 17... Work seating detection device 18... Operation display device 21... Seating surface 22... Detection hole 23... Air pipe 24... Air supply source 25... Electromagnetic on-off valve 26 ... Pressure control valve 27 ... Seating sensor (flow rate sensor) 28 ... Relay device

Claims

a detection hole for releasing air from the seating surface of the chuck that grips the work;
an air supply channel for sending air from an air supply source to the detection hole;
a pressure control valve provided in the air supply channel;
a seating sensor provided in the air supply passage on the secondary side of the pressure control valve;
a relay device that transmits measurement data measured by the seating sensor;
a control device that calculates a threshold for seating determination based on the display of the measurement data acquired via the relay device on an operation display device and the operation of the operation display device;
Work seating detection device.
The seating sensor is a flow rate sensor that measures the flow rate of air flowing out of the detection hole, and the control device displays the flow rate value and its measurement time on the screen of the operation display device from the measured value measured by the seating sensor. 2. The workpiece seating detection device according to claim 1, wherein a graph showing the relationship between is displayed.
The operation display device displays the measured value by the seating sensor, and the measured value is arbitrarily imported into the control device by operating a measured value import button, and the control device uses the imported measured value to display the threshold value. 3. The workpiece seating detection device according to claim 1 or 2, wherein .
4. The workpiece seating detection device according to any one of claims 1 to 3, wherein the controller stores the measured value measured by the seating sensor together with the measurement time as workpiece chuck information in a storage unit.
A processing threshold value for detecting a seating state during workpiece processing is set in the control device, and the control device executes predetermined control when a measured value of the seating sensor exceeds the processing threshold value. Work seating detection device according to any one of.