JP2008204366A - Machine tool equipped with cylinder-type balancing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein there is a risk of collision between a tool and a workpiece, when an abnormality occurs to the pressure of compressed air or pressurized oil in a balancing device. <P>SOLUTION: A pressure sensor 33 outputs a pneumatic pressure abnormality signal to a numerical control device 10. The numerical control device 10 outputs a brake signal to make a braking device 4 operate. The numerical control device 10 outputs movement command data for gradually reducing speed at each position on a predetermined relative movement locus, to a motor control device 20 and stops the output of the movement command data, after a predetermined speed reducing time. The motor control device 20 synchronously performs drive control of feed motors 13, 15, 17, based on the movement command data and outputs stop signals, respectively when the speed detected for each synchronous control shaft is 0. The numerical control device 10 outputs movement command data for making a movable body 16 of a main spindle lift, when inputting all stop signals. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a machine tool including a cylinder type balance device using an air cylinder or a hydraulic cylinder. In particular, the present invention relates to a machine tool configured to operate a brake device to prevent a moving body from falling when a failure occurs in a balance device.

  Using the axial direction where the tool is attached as the main axis, the tool such as an end mill or a bite and the work piece are moved relative to each other in the horizontal control axis direction and the vertical control axis direction which are perpendicular to each other by the axis feeder. A machine tool for cutting a workpiece into a desired machining shape is known. Such a machine tool is generally provided with a computer numerical controller (CNC), and synchronizes the moving body of the axis feeder of each synchronous control axis based on a movement command output from the numerical controller. The movement is controlled so that the tool moves relative to the workpiece along a predetermined relative movement locus.

  The motor control device includes a servo control circuit and a power amplifier, and controls each axis feeding device based on a movement command output from the numerical control device. The servo control circuit of each synchronous control axis outputs a voltage command to the power amplifier according to the movement command. The power amplifier outputs a drive current corresponding to the voltage command to the servo motor of the shaft feeder to drive the servo motor to move the moving body in a predetermined direction. The servo control circuit outputs a speed command based on the positional deviation between the position command and the detected moving body position, and outputs a current command based on the speed deviation between the output speed command and the detected servo motor speed. The voltage command is output based on the deviation between the current command and the detected drive current output from the power amplifier, so that the moving body is always positioned and controlled.

  By the way, when the control axis is a vertical axis in which gravity acts in the axial direction, that is, a so-called gravity axis, a downward force is applied to the moving body, so that the movable part including the moving body is offset so as to cancel the downward force. A balance device for providing a counter balance weight that balances the mass is provided. In addition, when the servo motor is de-energized, the moving body falls by its own weight, and therefore a brake device is provided to stop the moving body so that the moving body does not fall.

  As one of balance devices for providing a counter balance weight, there is a cylinder type balance device using an air cylinder or a hydraulic cylinder. The cylinder type balance device has an advantage that it has a follow-up property and the counter balance weight can be easily adjusted as compared with the weight suspension type balance device. For example, as disclosed in Patent Document 1, an air balancer supplies compressed air from an air source such as a compressor to a cylinder chamber in a cylinder cylinder of an air cylinder with a predetermined pressure by an air regulator and moves a piston. Accordingly, a constant counterbalance weight is provided by supplying and exhausting air in and out of the cylinder chamber to maintain a predetermined pressure.

  The brake device is generally configured to mechanically stop the movement of the moving body when an abnormality occurs. By configuring the moving body to mechanically stop, the moving body can be stopped even when power is not supplied. As one of the brake devices, a brake device of a type that can be provided in a machine tool having a transmission mechanism using a ball screw and a nut and mechanically stops the rotation of the ball screw is used. As one of the brake devices, a brake device of a type that can be provided in a machine tool having a cylinder type balance device and mechanically holds a piston rod of the cylinder is considered. A brake device that holds the piston rod of a cylinder is disclosed in Patent Document 1.

  If the compressor or pressure pump stops due to a power failure or failure, or the piping is damaged and compressed air or pressurized oil leaks, the pressure of the compressed air or pressurized oil supplied to the cylinder decreases, and the balance force A large load is applied to the servo motor. The servo motor has a rated current, and when an excessive control current exceeding the rated current flows due to overload, a protection circuit works to prevent the servo motor from burning out and the servo motor is de-energized. When the servo motor is de-energized, the moving body falls. Therefore, in a machine tool equipped with a cylinder type balance device, when an abnormality occurs in the pressure of compressed air or pressurized oil in the balance device, the brake device is activated to stop the moving body, and the moving body falls. Has been to prevent.

  A system for controlling a balance device and a brake device disclosed in Patent Document 1 includes a pressure switch for detecting a decrease in the pressure of compressed air maintained at a predetermined pressure by an air regulator in an air supply device of the balance device. When the compressed air pressure drops below the required pressure, the control device closes the electromagnetic valve to forcibly stop the supply of compressed air to the brake device so that the brake device can be operated quickly and reliably. Constructed for safety.

Japanese Patent No. 3315945 (paragraphs 0020-0038)

  Depending on the structure of the brake device, the brake device that mechanically stops the movement of the moving body may include slippage, play, or backlash between the base portion and the stop portion, which occurs between the stop member and the stop member. Therefore, when the drive of the servo motor is stopped for repair or the like while the brake is applied, the entire load of the movable part is applied to the brake device and the moving body descends to some extent. In particular, in the case of a linear motor drive type shaft feed device with extremely low frictional resistance, the load applied to the brake device becomes larger. Therefore, if the servo motor is de-energized after an abnormality occurs in the balance device during machining and the brake device is activated, the tool collides with the workpiece and the tool is damaged or the workpiece is There is a risk of injury.

  Also, when the pressure of the compressed air or pressurized oil of the balance device drops below a predetermined pressure and the brake device is operated, machining cannot be continued. Although all the moving bodies of the control shaft must be stopped immediately, when stopping all the moving bodies, the tool may bite into the workpiece and damage the workpiece. Therefore, there is a problem that when a failure occurs in the balance device, a failed product is produced.

  An object of the present invention is to provide a machine tool equipped with a cylinder type balance device, and when an abnormality occurs in the pressure of compressed air or pressurized oil in the balance device, the moving body descends and the tool and workpiece are moved. The object is to provide a machine tool that prevents collisions. Another object of the present invention is to provide a machine tool equipped with a cylinder type balance device, and when an abnormality occurs in the pressure of compressed air or pressurized oil in the balance device, the tool bites into the work piece to be covered. It is to provide a machine tool that prevents the workpiece from being damaged. Several other advantages of the present invention are specifically described in the best mode for carrying out the invention.

  In order to solve the above problems, the machine tool of the present invention has an abnormality in the pressure of the balance device in a machine tool including a balance device that applies a counter balance weight to the vertical axis by the pressure of compressed air or pressurized oil. A control device for controlling the tool to move the main body moving in a direction in which the tool moves away from the workpiece by a predetermined distance tool that can avoid interference between the tool and the workpiece, and to operate a brake device provided on the vertical shaft. Is provided.

  Another machine tool of the present invention is a machine tool that has a synchronous control axis in two horizontal axes and one vertical axis, and performs machining by moving a tool relative to a workpiece along a predetermined relative movement locus. In a machine tool having a balance device that applies a counter balance weight to the vertical axis by the pressure of compressed air or pressurized oil, the tool moves on a predetermined relative movement locus when an abnormality occurs in the pressure of the balance device. Each movable body of the synchronous control shaft can be decelerated and stopped at a predetermined acceleration or deceleration time so that it moves and stops, so that interference between the tool and the workpiece can be avoided. A control device is provided for controlling the moving body to move and for controlling the brake device provided on the vertical shaft.

  Specifically, it is a machine tool that has a synchronous control axis in two horizontal axes and one vertical axis, and performs machining by moving a tool relative to a workpiece along a predetermined relative movement locus. In a machine tool equipped with a balance device that applies a counter balance weight to the vertical axis by the pressure of air or pressurized oil, when an abnormality occurs in the pressure of the balance device, the speed at each position on a predetermined relative movement trajectory is predetermined. All servo motors or all moving bodies of the synchronous control axes were stopped by controlling each servo motor based on a command that includes each position that gradually decreases and stops at the acceleration or deceleration time and the speed at each position. The spindle servo motor is controlled based on a command to move the spindle moving body in a direction in which the tool and workpiece are separated by a predetermined distance that can sometimes avoid interference between the tool and the workpiece. Provided with a control device for controlling to operate the brake device provided on the vertical axis.

  In the machine tool of the present invention, when the pressure of the compressed air or pressurized oil of the balance device drops below a required pressure, the moving body of the spindle is moved and the brake device is operated so that the tool and the workpiece are separated. As a result, the brake device prevents the moving body from dropping, and when the servo motor is de-energized for repair, etc., even if the moving body descends to some extent due to brake slipping, etc., the tool and workpiece The workpiece does not collide and the workpiece is not damaged.

  Another machine tool according to the present invention is configured so that the tool moves on a predetermined relative movement locus and stops when the pressure of the compressed air or pressurized oil of the balance device drops below a required pressure. Since each moving body of the control shaft is decelerated and stopped, the tool stops on a predetermined relative movement locus without causing overshoot. As a result, even when an abnormality occurs in the balance device during machining, a failed product is not produced, and loss can be minimized.

  FIG. 1 shows a general outline of a machine tool as a preferred embodiment of the present invention. The machine tool includes a machine main machine 1, a control device 2, a balance device 3, and a brake device 4. Further, an auxiliary device such as an automatic tool changer (ATC) or a coolant supply device (not shown) is appropriately provided as necessary. The attached device is controlled by the control device 2. The balance device 3 is configured to give a counter balance weight to the vertical axis by the pressure of compressed air or pressurized oil.

  The machine tool of the embodiment uses a vertical axis that is a gravity axis as a main axis. The main axis is the axial direction in which the tool 5 is attached. The machine tool according to the embodiment includes an axis feeding device that is controlled by the control device 2 on each synchronous control axis, with the main axis being the Z axis and the two horizontal directions orthogonal to each other being the X axis and the Y axis. The machine tool of the embodiment has a spindle that rotates the tool 5 at high speed by the spindle rotating motor 11 with the spindle rotating shaft as the R axis. A machine tool configured to index the rotation angle of a tool or a workpiece around a spindle for automatic tool change or using a tool such as a tool, a spindle rotating motor with a spindle rotating axis as a C axis. Has a machining head or a turntable that can be used for indexing the rotation angle.

  The X-axis direction axis feeding device provided in the machine main unit 1 includes a column as a moving body 12 and an X-axis feeding motor 13 as a servo motor. The axis feeding device in the Y-axis direction includes a table that is a moving body 14 and a Y-axis feeding motor 15 that is a servo motor. The axis feeding device in the main axis Z-axis direction includes a slider that is a moving body 16 and a Z-axis feeding motor 17 that is a servo motor. Each of the feed motors 13, 15, and 17 in the embodiment is a linear motor, and includes a primary side mover including an exciting coil and a secondary side stator including a magnet plate on which permanent magnets are arranged.

  A spindle for rotating the tool 5 is provided in the machining head, and the machining head is attached to the moving body 16. The moving body 16 is supported on the moving body 12 by a guide (not shown) so as to be able to reciprocate in the main axis Z-axis direction. The workpiece 6 is placed on the moving body 14. Therefore, by controlling the feed motors 13, 15, and 17 provided on the respective synchronous control shafts synchronously with the control device 2, the moving bodies 12, 14, 16 are synchronously controlled to move, and the tool 5 is controlled. The workpiece 6 can be relatively moved along a predetermined relative movement locus according to a desired machining shape. The bed, which is a base on which the moving body 12 and the moving body 14 are arranged, is not shown.

  The control device 2 includes a computer numerical control device 10 and a motor control device 20. The motor control device 20 includes a servo control circuit 21 and a power amplifier 22. The control device 2 is a moving body of a spindle in a direction in which a predetermined distance tool 5 that can avoid interference between the tool 5 and the workpiece 6 when the abnormality occurs in the pressure of the compressed air of the balance device 3 is separated from the workpiece 6. 16 is moved and the brake device 4 provided on the gravity axis is controlled to operate.

  The timing at which the control device 2 operates the brake device 4 is different in a state in which the pressure of the compressed air in the balance device 3 decreases. Basically, it may be any time before the moving body 16 is moved, at the same time as the moving body 16 is moved, or after the moving body 16 is moved, but the pressure of the compressed air of the balance device 3 is required. Since the balance force is being lost due to the drop from the pressure, it is desirable to operate at an early point after the drop in the pressure of the compressed air is detected in order to reliably prevent the moving body from dropping.

  The control device 2 controls the movable bodies 12, 14, 16 of the synchronous control shaft so that the tool 5 moves on a predetermined relative movement locus and stops when an abnormality occurs in the pressure of the compressed air of the balance device 3. Control is performed such that the predetermined distance tool 5 that can avoid interference between the tool 5 and the workpiece 6 after the deceleration and stop at a predetermined acceleration or deceleration time moves the spindle moving body 16 in a direction away from the workpiece 6. At the same time, the brake device 4 provided on the gravity axis is controlled to operate.

  The balance device 3 according to the embodiment is an air balancer that applies a counter balance weight to the gravity axis by the pressure of compressed air. The balance device 3 includes an air cylinder 31 and an air supply device 32 that supplies the air cylinder 31 with compressed air controlled to a predetermined pressure. Further, the balance device 3 is provided with a pressure sensor 33 for detecting that the pressure of the compressed air supplied to the air cylinder 31 has dropped below a predetermined value in the air supply pipe line of the air supply device 32. The pressure sensor 33 is turned on when the pressure of the compressed air maintained at a predetermined pressure supplied to the air cylinder 31 drops below a required pressure, and a signal (hereinafter referred to as an abnormal air pressure signal) is controlled. 2 is a pressure switch that outputs to 2. Further, the balance device 3 is provided with an electromagnetic valve 34 that stops the operation of the air cylinder 31 by stopping the supply of compressed air from the compressor to the air cylinder 31. The electromagnetic valve 34 is controlled to be opened and closed by the control device 2 through the electromagnetic valve control circuit 30.

  The tip of the piston rod of the air cylinder 31 is fixed to an attachment member fixed to the moving body 14. The cylinder of the air cylinder is attached to a moving body 16 provided so as to be movable with respect to the moving body 14. Accordingly, as the moving body 16 moves, the cylinder cylinder moves in the vertical direction, and the piston at the other end of the fixed piston rod moves in the cylinder cylinder, so that the volume in the cylinder chamber changes.

  The balance device 3 supplies and exhausts air in the upper cylinder chamber from the supply port across the piston formed in the cylinder cylinder, so that the moving body 16 moves in the gravitational axis direction and the relative position of the piston changes. As the volume of the cylinder chamber changes, the amount of air in the cylinder chamber is increased or decreased so that the air pressure in the cylinder chamber is maintained at a predetermined pressure that provides a constant counterbalance weight. When the air pressure in the upper cylinder chamber is maintained constant, a balance force corresponding to a constant counter balance weight is generated on the gravity axis. Therefore, a counter balance weight corresponding to the mass of the movable part including the moving body 16 is given to the gravity axis regardless of the position of the moving body 16.

  The air supply device 32 controls the air cylinder 31 by adjusting the compressed air from an air source such as a compressor so as to maintain the set pressure. The air supply device 32 mainly includes an air source such as a compressor, a filter 310 that removes dust from compressed air from the air source, an oil mist filter 320 that removes oil mist from the compressed air, and a predetermined amount of compressed air. The air regulator 330 for adjusting the pressure and the pressure of the air in the cylinder cylinder of the air cylinder 31 are maintained in a predetermined pressure that can balance the moving body 16. And a relief air regulator (high relief air regulator) 340 which is a pressure adjusting device configured to supply and exhaust air in a large amount and at high speed. The air supply device 32 includes an emergency reservoir tank (not shown).

  The brake device 4 includes a brake main body 41 provided at a cylinder end of the air cylinder 31, an air supply device 32 that supplies constant pressure compressed air to the brake main body 41, and air between the brake main body 41 and the air supply device 32. An electromagnetic valve 42 provided in the supply pipeline and an electromagnetic valve control circuit 30 that controls opening and closing of the electromagnetic valve 42 are included. The brake body 41 moves together with the cylinder cylinder of the air cylinder 31. Therefore, the brake main body 41 moves in the vertical direction as the moving body 16 moves.

  When the compressed air of a predetermined pressure is supplied, the brake device 4 of the embodiment opens the lever against the force of the compression coil spring so that the brake is not applied, and the compressed air of the predetermined pressure When not supplied, the lever is closed by the force of the compression coil spring, and the piston rod of the air cylinder 31 is pressed and held by the restraining member to restrain the cylinder cylinder and the movable body 16 attached with the cylinder cylinder from moving. It is the structure to do. The specific configuration of the brake device 4 is disclosed in Patent Document 1, and the description of the specific configuration is omitted as referring to Patent Document 1.

  When the machine tool is operating normally, the electromagnetic valve 42 is opened and compressed air of a predetermined pressure is supplied from the air supply device 32 to the brake body 41. Therefore, the lever is normally opened and the brake is not applied. When a brake signal is output from the control device 2 to the solenoid valve control circuit 30, the relay circuit provided in the solenoid valve control circuit 30 is turned on and the solenoid valve 42 is closed. It will not be supplied. Therefore, the lever is closed and the brake is applied.

  The brake device 4 is not limited to the embodiment, and any brake device may be used as long as the moving body is stopped by the frictional force, and a known brake device is employed. For example, the stop plate is separated from the rotating plate that rotates together with the ball screw of the shaft feeder so that the brake is not applied, and the moving body does not move by pressing the stop plate against the rotating plate and stopping the rotation of the ball screw. There is a brake device configured to stop.

  The numerical controller 10 of the control device 2 sends movement command data for controlling the motors of the control axes of the X axis, the Y axis, the Z axis, which are synchronous control axes, and the R axis, which is an independent control axis, to the motor control apparatus 20. Output. The servo control circuit 21 and the power amplifier 22 of the motor control device 20 are provided for each control axis. The numerical control apparatus 10 uses movement command data for driving and controlling the feed motors 13, 15, and 17 to move the moving bodies 12, 14, and 16 so that the tool 5 relatively moves along a predetermined relative movement locus. Distribution output is performed in synchronization with each servo control circuit 21 of each synchronous control axis of the control device 20. Further, the numerical control device 10 outputs movement command data for driving and controlling the spindle rotating motor 11 to the R-axis servo control circuit 21 of the motor control device 20 so that the tool 5 rotates at a set rotation speed at a high speed. When the spindle rotation axis is the C-axis, the movement command data is output to the C-axis servo control circuit 21 in synchronization with the movement command data output to each servo control circuit 21 of the synchronous control axis.

  The movement command data output from the numerical controller 10 to each servo control circuit 21 of each synchronous control axis is data that can obtain the position, position and speed, or position, speed, and acceleration. The movement command data output to the R-axis servo control circuit 21 is data that can obtain the rotational speed, rotational speed and acceleration, or rotational position, rotational speed, and acceleration. The servo control circuit 21 has an arithmetic device (not shown). Further, the motor control device 20 can be provided with an arithmetic device independently of the servo control circuit 21. Therefore, a part of the calculation function of the numerical controller 10 can be borne by the motor controller 20. The movement command data output from the numerical control device 10 to the motor control device 20 differs depending on the arithmetic functions that the numerical control device 10 and the motor control device 20 have. In the machine tool of the embodiment, the movement command data output from the numerical control device 10 to each servo control circuit 21 of the synchronous control axis is position data per unit time.

  Each movement command data of each synchronous control axis input to the motor control device 20 is converted into a position command value indicating a position with respect to time in each servo control circuit 21 and given to the servo control system. The numerical controller 10 recognizes the current position of each synchronous control axis based on the movement command data output to the motor controller 20. Further, the R-axis movement command data of the main shaft rotation axis is converted into a speed command value indicating the rotation speed with respect to time in the R-axis servo control circuit 21 and is given to the servo control system. In the present invention, a control system that does not have a position control system is also referred to as a servo control system. Further, when the spindle rotation axis shares the R axis and the C axis, the servo control circuit 21 can switch the servo control system between the R axis and the C axis.

  The numerical control device 10 obtains position data for each unit time on a predetermined relative movement locus according to a predetermined acceleration and a set machining speed, and outputs movement command data. The numerical controller 10 according to the embodiment decodes the NC program and obtains position data on a predetermined relative movement locus. In the NC program, a tool path (program path) is described. Since the program locus is the locus of the center of the tool 5, the machining shape locus formed on the workpiece is shifted from the program locus by the radius of the tool 5, as in the case where the tool 5 to be used is a ball end mill. If there is, the offset locus obtained by correcting the program locus with the tool radius is obtained. Therefore, the predetermined relative movement trajectory referred to in the present invention is a program trajectory when tool radius correction is not required, and an offset trajectory when tool radius correction is required.

  Each servo control circuit 21 obtains a position deviation between the position command and the current position of the moving body detected by a position detector (not shown), and gives a proportional gain to obtain a speed command. Then, a speed deviation between the speed command and the current speed of the servo motor detected by a speed detector (not shown) is obtained, and a proportional integral gain is given to obtain a current command. Further, a current deviation between the speed command and a drive current flowing through the servo motor detected by a current detector (not shown) is obtained, and a voltage command is output to the power amplifier 22. A power amplifier 22 provided for each synchronous control axis of the motor control device 20 controls a power element based on a voltage command and outputs a drive current to each feed motor 13, 15, 17.

  When the air pressure abnormality signal is input from the pressure sensor 33, the numerical control device 10 has a position at which the speed at each position on the predetermined relative movement trajectory gradually decreases with a predetermined acceleration or deceleration time and stops. The tool is controlled when all the feed motors 13, 15, 17 or all the moving bodies 12, 14, 16 of the synchronous control shaft are stopped by controlling the feed motors 13, 15, 17 based on the command including the speed at each position. The spindle feed motor 17 is controlled and the brake device 4 is controlled based on a command to move the spindle moving body 16 in a direction in which the tool 5 and the workpiece 6 move away from each other by a predetermined distance 5 that can avoid interference between the workpiece 5 and the workpiece 6. Control to operate.

  When the air pressure abnormality signal is input, the numerical controller 10 is configured so that each position on the predetermined relative movement trajectory and each position where the speed at each position gradually decreases with a predetermined acceleration or deceleration time and stops. Since the movement command data including the speed at the position is output, a drive current corresponding to the movement command data is output from each power amplifier 22 through each servo control circuit 21 of each synchronization control axis, and each feed motor of each synchronization control axis. Each of the moving bodies 12, 14, and 16 is decelerated and stopped by decelerating and stopping 13, 15, and 17. Therefore, the tool 5 moves on a predetermined relative movement locus and stops.

  A command given to the servo control circuit 21 that includes each position where the speed at each position on the predetermined relative movement trajectory gradually decreases and stops at a predetermined acceleration or deceleration time and the speed at each position is a numerical value. It can be obtained by calculation by the motor control circuit 20 without obtaining it from the movement command data output from the control device 10. In such a configuration, the motor control device 20 calculates the above command when the compressed air pressure of the balance device 3 falls below a required pressure, and inputs the movement command data from the numerical control device 10. At the same time, the above command is converted into a position command value indicating a position with respect to time and given to the servo control system. At this time, the predetermined acceleration or deceleration time is preset in the motor control device 20 through the numerical control device 10.

  The numerical control device 10 detects an air pressure abnormality signal, and detects each of the feed motors 13, 15, 17 or the moving bodies 12, 14, 16 of each synchronous control shaft from a speed detector (not shown). A stop signal output from each servo control circuit 21 of the motor control device 20 when the speed becomes 0 is input. The numerical control device 10 receives movement command data for moving the movable body 16 of the spindle Z axis in a direction in which the predetermined distance tool 5 and the workpiece 6 are separated when all stop signals are input. 20 is output. The amount of movement, feed speed, and acceleration / deceleration time (acceleration) for moving the predetermined distance moving body 16 are set in advance. In the machine tool of the embodiment, since the main axis and the gravity axis coincide with each other, the moving body 16 is raised by a predetermined distance. The stop signal can be configured to be input directly to the numerical controller 10 from the speed detector.

  If the brake device 4 is already operating, the moving body 16 must be moved against the frictional force of the brake device 4. At this time, if it is attempted to pull it up slowly, the force of the feed motor 17 may not overcome the frictional force of the brake device 4 and the overload protection circuit of the feed motor 17 may be activated and the feed motor 17 may be de-energized. . Therefore, in order to pull up the moving body 16 overcoming the frictional force of the brake device 4, it is necessary for the feed motor 17 to instantaneously generate a large force when the moving body 16 starts to move up. In particular, in the case where the piston rod is held by the restraining member as in the brake device 4 of the embodiment, once the moving body 16 starts moving, it can be pulled up as it is. Therefore, the acceleration / deceleration time when moving the moving body 16 by a predetermined distance is relatively short. In other words, it is desirable that the acceleration be set to a value as large as possible.

  The predetermined distance is a sufficient distance at which the tool 5 and the workpiece 6 do not interfere with each other. For example, in the case of a machine tool having a configuration in which the main shaft and the gravity axis coincide with each other, the distance from which the moving body 16 descends due to slipping of the brake device 4 after the brake device 4 is activated and the feed motor 17 is excited is cut off. It is a big distance. In the case of a machine tool having a configuration in which the main axis is on a single horizontal axis perpendicular to the gravity axis, the tool 5 is a distance away from the surface of the workpiece 6 before processing. By separating the tool 5 and the workpiece 6 by the predetermined distance in this way, when the moving body 16 is lowered by a certain distance due to the structural problem of the brake device 4 after the excitation of the feed motor 17 is cut off, the tool 5 and the workpiece 6 do not collide and the tool 5 is not damaged or the workpiece 6 is not damaged.

  A command given to the servo control circuit 21 to move the movable body 16 of the main spindle Z-axis in the direction in which the predetermined distance tool 5 and the workpiece 6 are separated from the movement command data output from the numerical controller 10. Without being obtained, it can be obtained by calculation by the motor control circuit 20. When configured in this way, the motor control device 20 causes the spindle Z axis to move away from the predetermined distance tool 5 and the workpiece 6 when all the speed detectors detect that the speed is zero. A command including a position for moving the moving body 16 and a speed at each position is calculated, and the command is converted into a position command value indicating a position with respect to time and given to the servo control system. At this time, the moving amount, feed speed, and acceleration / deceleration time (acceleration) for moving the predetermined distance moving body 16 are preset in the motor control circuit 20 through the numerical control device 10.

  The numerical controller 10 operates the brake device 4 when an air pressure abnormality signal is input. The brake device 4 according to the embodiment normally has a structure in which compressed air is supplied from an air supply source common to the air supply source of the balance device 3, and the brake device 4 operates when the compressed air is not supplied. Therefore, when the pressure of the compressed air of the balance device 3 rapidly decreases, the balance device 3 operates before being controlled by the numerical control device 10. The numerical control device 10 outputs a brake signal for operating the brake to the electromagnetic valve control circuit 43 and closes the electromagnetic valve 42 even after the brake device 4 has already been operated. When the compressed air of the balance device 3 gradually decreases, the numerical control device 10 outputs a brake signal, the relay circuit of the electromagnetic valve control circuit 43 is turned on, and the electromagnetic valve 42 is closed, thereby braking the brake device. 4 is activated.

  The numerical control device 10 stops the output of the movement command data to the servo control circuit 21 of the R axis after moving the moving body 16 of the main axis Z axis by a predetermined distance, and stops the spindle rotation motor 11. Preferably, the speed command is set to zero. The spindle 6 is stopped after the tool 5 is separated from the workpiece 6 to prevent the workpiece 6 from being damaged.

  FIG. 2 shows a preferred embodiment of the control device 2. The configuration of the control device 2 shown in FIG. 2 is represented by a block diagram, and each element (each part) does not indicate the actual arrangement of parts. Therefore, each element arranged in the numerical control device 10 shown in FIG. 2 does not need to be provided in the numerical control device 10 as shown in the figure, and is within a range in which the operation of the control device 2 in the present invention is realized. The motor controller 20 can be provided. FIG. 2 shows the functions directly related to the present invention extracted from the functions of the numerical control apparatus 10.

  The trajectory analysis unit 110 of the numerical control device 10 decodes the NC program and obtains a position vector at a control point on a predetermined relative movement trajectory according to a desired machining shape and a shape of the predetermined relative movement trajectory. When the tool diameter is corrected, the offset locus is set as a predetermined relative movement locus. The NC program is directly input from an input device such as a keyboard (not shown), read from a storage device such as a magnetic disk device or a USB memory (USB, Universal Serial Bus), or from a storage device such as a hard disk device. Read out.

  The position data calculation unit 120 of the numerical control device 10 is arranged on the relative movement trajectory based on the position vector output from the trajectory analysis unit 110, the shape of a predetermined relative movement trajectory, a predetermined acceleration, and a set machining speed. The position for every predetermined unit time is calculated. The predetermined unit time is determined in advance according to the processing capacity of the motor control device 20. In the embodiment, the predetermined unit time is 1 msec (millisecond). The position data calculation unit 120 is a deceleration point on a predetermined relative movement trajectory based on a predetermined acceleration and a set machining speed based on the curvature of a curve obtained from the shape of the predetermined relative movement trajectory or a turning point of a corner. And the acceleration point etc. are judged and the position for every predetermined unit time is calculated | required sequentially from a position vector according to a process progress direction.

  When the pressure of the compressed air of the balance device 3 falls below the required pressure and the mobile bodies 12, 14, and 16 are all decelerated and stopped, the position data calculation unit 120 is configured so that the mobile bodies 12, 14, and 16 are all After stopping, the output of position data per unit time in a predetermined relative movement locus is stopped. Then, the current position where the moving body 16 of the main spindle Z-axis is stopped is acquired, and the amount of movement in the direction in which the tool 5 and the workpiece 6 are separated from each other, and the preset feed speed and acceleration / deceleration time (acceleration) are obtained. Based on this, the position for every predetermined unit time is calculated. The amount of movement is set in advance according to a sufficient predetermined distance at which the tool 5 and the workpiece 6 do not interfere with each other and the direction in which the tool 5 and the workpiece 6 are separated from each other based on the configuration of the machine main machine 2 of the machine tool.

  The movement command data output unit 130 of the numerical controller 10 sets a reference time (hereinafter referred to as a time base) and measures the time. The time base can be changed. The time base is normally set to the same time as the predetermined unit time. The movement command data output unit 130 sequentially distributes position data for each predetermined unit time to the respective synchronous control axes and outputs them to the respective servo control circuits 21 of the respective synchronous control axes as movement instruction data at time intervals according to the time base. In the embodiment, when the time base is set to the same time as the predetermined unit time, the position data for every 1 msec obtained by the position data calculation unit 120 is used as each of the servo control circuits as movement command data at a time interval of 1 msec. 21 is distributed and output.

  When the time base is changed, the movement command data output unit 130 outputs each position data of each synchronous control axis to each servo control circuit 21 at time intervals according to the changed time base. The time base is changed according to the override setting value. The override is set as a percentage, and when it is 100%, it is set to the same time as the predetermined unit time. The time base is changed in proportion to the percentage as the override setting value becomes smaller with reference to 100%. For example, when the override is set to 50%, the time base is extended twice. In the embodiment, when the time base is doubled, the position data for every 1 msec obtained by the position data calculation unit 120 is distributed and output to each servo control circuit 21 as movement command data at a time interval of 2 msec. Is done.

  Since the movement command data is position data that is output at time intervals according to a time base based on position data for each predetermined unit time according to a predetermined acceleration and a set machining speed, positions that are output continuously The data can be expressed as a function of position with respect to time, and the command speed and acceleration can be obtained. Therefore, the movement command data includes each position and the speed at each position. The command speed obtained from the movement command data changes at time intervals of continuously output position data. When the time base is a predetermined unit time, the command speed is set by accelerating according to a predetermined acceleration. Movement command data that reaches and maintains the machining speed is output.

  When the time base is changed, the command speed commanded by the changed time base magnification changes. Therefore, when the override is set to 50%, the time base is doubled and the command speed is 2 It will be a fraction. When the override is set to 0%, the time base becomes infinite and movement data is not output. However, if the command speed is suddenly changed, the maximum acceleration is exceeded, and the feed motors 13, 15, 17 of each synchronous control shaft cannot follow and the tool 5 deviates from a predetermined relative movement locus. If the movement command is suddenly stopped, the feed motors 13, 15, and 17 of each coaxial control shaft try to stop suddenly, but the moving bodies 12, 14, and 16 cannot stop immediately due to inertia. The tool 5 deviates from a predetermined relative movement locus and causes an overshoot.

  Therefore, when the override setting value is changed, a change time (acceleration time or deceleration time) for changing the time base linearly stepwise is determined in advance. The change time is set in advance according to the override setting value to be changed or the change range of the override setting value. Therefore, when the override setting value is changed, the time base changes linearly during a predetermined change time, and the time interval at which the position data is output changes to decelerate or accelerate to the changed speed. Such a command speed can be obtained.

  The numerical control device 10 of the embodiment sets the change time to 200 msec when the override setting value becomes 0%. Therefore, when the override setting value is changed to 0%, the time interval is gradually increased during the change time of 200 msec, position data is output, and position data is not output after 200 msec. In other words, movement command data including each position and the speed at each position is output so that the speed gradually decreases and stops at a predetermined deceleration time. As a result, the moving bodies 12, 14, and 16 of the respective synchronous control shafts are decelerated and stopped in synchronization with a predetermined deceleration time so that the tool 5 moves along a predetermined relative movement locus and stops. The numerical control apparatus 10 according to the embodiment outputs the movement command data on a time base with a predetermined unit time as a reference, so that the change time (acceleration time or deceleration time) is set. Can be set.

  The movement command data output unit 130 is a position data output unit when the override set value is set to 100% after the pressure of the compressed air of the balance device 3 decreases and all the moving bodies 12, 14, 16 stop. A predetermined predetermined distance calculated so that the tool 5 of the main spindle Z-axis and the workpiece 6 do not interfere with each other. The position data for each unit time based on the time (acceleration) is output to the servo control circuit 21 of the spindle Z-axis at time intervals according to the time base as movement command data including each position and the speed at each position. As a result, the moving body 16 of the main spindle Z axis rises by a predetermined distance where the tool 5 and the workpiece 6 do not interfere with each other and stops.

  The air pressure abnormality processing unit 140 of the numerical controller 10 sets the override setting value of the movement command data output unit 130 to 0% when an air pressure abnormality signal is input from the pressure sensor 33. When the override setting value is set to 0%, the movement command data output unit 130 linearly changes the time base so that the time base gradually increases with a preset change time (deceleration time). The movement command data is output, and the output of the movement command data is stopped after the change time.

  The air pressure abnormality processing unit 140 causes the movement command data output unit 130 to stop outputting the movement command data and then inputs all the stop signals from the servo control circuits 21 of the respective synchronous control axes. The output of the position data for every predetermined unit time from the calculation unit 120 is stopped. Then, the override setting value of the movement command data output unit 130 is returned to 100%, and the position data calculation unit 120 causes the movable body 16 of the spindle Z axis to be set in advance so that the tool 5 and the workpiece 6 do not interfere with each other. Position data for each predetermined unit time is output so that the distance tool 5 moves a predetermined distance in a direction away from the workpiece 6.

  The air pressure abnormality processing unit 140 outputs a brake signal to the electromagnetic valve control circuit 43 to operate the brake device 4 when the pressure of the compressed air of the balance device 3 decreases. Preferably, the brake signal is output as soon as possible by inputting the air pressure abnormality signal. Further, the output of the rotation speed data from the spindle rotation control unit 150 is stopped, and the rotation of the spindle rotation motor 11 is stopped.

  The spindle rotation control unit 150 outputs rotation speed data according to the set rotation speed to the movement command data output unit 160. The maximum acceleration of the spindle motor 11 is preset in the R-axis servo control circuit 21 through the spindle rotation control unit 150. The spindle rotation control unit 150 outputs from the spindle Z-axis servo control circuit 21 through the air pressure abnormality processing unit 140 when the moving body 16 of the spindle Z-axis rises by a predetermined distance and stops due to a decrease in the compressed air of the balance device 3. The output of the rotation speed data is stopped in response to the stop signal.

  The movement command data output unit 160 outputs the rotational speed data to the R-axis servo control circuit 21 as movement command data. The R-axis servo control circuit 21 gives a speed command value indicating a speed with respect to time to the servo control system according to a predetermined acceleration. In the servo control system, feedback control is performed by the speed detected by the speed detector and the drive current of the spindle motor 11 detected by the current detector.

  As already described, each element described above may be provided in either the numerical controller 10 or the motor controller 20 as long as the operation of the controller 2 is executed. Each element can be divided into two or more elements. In addition, any one of the elements can be provided as one element. Each element can be realized by one arithmetic circuit.

  FIG. 3 shows the operation of the numerical controller 10 shown in FIG. 2 according to the present invention. FIG. 4 shows the relationship between the command speed and time in each synchronous control axis. FIG. 4 shows the relationship between the command speed and the time in each of the X-axis, Y-axis, and Z-axis synchronous control axes from the top. The command speed of each synchronous control axis in FIG. 4 is synchronized. Also, the plus or minus of the command speed in FIG. 4 indicates the direction of movement. The operation of the machine tool of the present invention will be described below with reference to FIGS.

  When the operation of the machine tool is started, the NC program is decoded and an operation according to the NC code is executed in the decoded order (S1). When the NC code is a command for operating the attached device, the attached device is operated. Attached devices include automatic tool changers, automatic workpiece changers, coolant tanks, and the like. When the NC code is a code for ending the NC program, the specified end operation is performed.

  When the NC code is a command related to the movement of each synchronous control axis, the shape of a predetermined relative movement locus according to a desired machining shape is obtained from the NC data described in the NC program, and the position at the control point on the relative movement locus is obtained. A vector is obtained (S2). For example, when the shape of the relative movement trajectory is a straight line, the control point is the start point and end point of a straight line. In the case of a free curve such as an equispaced rationalized B-spline curve (NURBS, Non-Uniforom Rational B-Spline), it is a control point obtained by a known calculation method used for each free curve. When tool radius correction is performed, a locus obtained by offsetting the program locus is set as a predetermined relative movement locus.

  Next, position data for each predetermined unit time is obtained based on the position vector at each control point, the shape of the relative movement trajectory, the predetermined acceleration, and the set machining speed (S3). In the embodiment, the predetermined unit time is 1 msec. The position data for each predetermined unit time reaches the speed allocated based on the machining speed set by accelerating each moving body 12, 14, 16 of each synchronous control axis with a predetermined acceleration and moving. Thus, the acceleration point and the deceleration point are determined from the curvature of the curve and the turning direction of the corner.

  When the position data of each synchronous control axis for each predetermined unit time is obtained, the position data for each predetermined unit time is used as movement command data for each servo control circuit 21 of each synchronous control axis of the motor control device 20 at time intervals according to the time base. Distribution output is performed (S4). The initial value of the time base is set to a predetermined unit time. In the embodiment, it is 1 msec. Therefore, the position data of each synchronous control axis is output to each servo control circuit 21 every 1 msec.

  When the position data is output, the motor control device 20 converts it into a position command value indicating a position with respect to time based on each position data output at time intervals according to the time base, and gives it to the servo control system. Velocity is given by position differentiation and acceleration is given by speed differentiation. Therefore, as shown in FIG. 4, the feed motors 13, 15, and 17 of the respective synchronous control shafts are set by accelerating the respective moving bodies 12, 14, and 16 at a predetermined acceleration. The command speed is output so that the position on the predetermined relative movement trajectory is moved at a speed obtained by distributing the speed. As a result, the tool 5 relatively moves at a machining speed set along a predetermined relative movement locus.

  When an air pressure abnormality signal is input (S5), the brake device 4 is operated (S6), and at the same time, the override is set to 0% (S7). When the override is set to 0%, the time interval at which each position data is output gradually increases from the predetermined unit time of the initial value, and the position data is not output after a preset change time. In the embodiment, the change time (deceleration time) is set to 200 msec. Since the speed in each synchronous control axis is determined by the time interval at which each position data is output, as shown in FIG. 4, when an air pressure abnormality signal is input, the command speed gradually decreases and becomes 0 after 200 msec. Become. The position data output during this time is position data at a point on a predetermined relative movement locus. As a result, the tool 5 is decelerated and stopped while maintaining a position on a predetermined relative movement locus. Therefore, the override is not limited to 0%, and it is only necessary to give a command to reduce the speed to 0 so that each synchronous control axis is positioned on a predetermined relative movement locus.

  When a stop signal indicating that each feed motor 13, 15, 17 or each moving body 12, 14, 16 is stopped is input from all servo control circuits 21 of each synchronous control axis (S8), it is based on a predetermined relative movement locus. Stops calculation of position data every predetermined unit time. Then, a predetermined distance that does not cause the tool 5 and the workpiece 6 to interfere with each other, a preset movement amount based on a direction in which the tool 5 and the workpiece 6 leave, a preset speed, and an acceleration / deceleration time (acceleration). The main shaft Z-axis is moved and retracted. In the embodiment, since the main axis is the gravity axis, the moving body 16 is raised. The position on the predetermined relative movement locus where the moving bodies 12, 14, and 16 are stopped can be identified by the output position data and stored in the storage device.

  In the process of retracting the main spindle Z-axis, first, the override setting value is returned to 100% and the time base is set to the initial value (S9). In the embodiment, the time base is set to 1 msec. Since the current position at which the main spindle Z-axis is stopped is known, a position vector for moving the movement amount set from the current position is obtained, and position data for each predetermined unit time is determined based on the set acceleration and speed. Is obtained (S10). In the embodiment, the predetermined unit time is set to 1 msec, the acceleration / deceleration time is set to 50 msec, and the feed speed is set to the maximum speed during idle feed. In the embodiment, since the main shaft is a gravity axis, the moving body 16 is lowered to some extent due to the structural problem of the brake device 4 after the brake device 4 is applied and the feed motor 17 is de-energized. The amount of movement is determined based on a distance greater than the distance.

  When the position data for each predetermined unit time is obtained, the position data for each predetermined unit time is output to the servo control circuit for the spindle Z-axis at time intervals according to the time base (S11). Then, output of position data is stopped when position data corresponding to a preset amount of movement is output. Therefore, as shown in FIG. 4, the moving body of the main spindle Z-axis is accelerated at a time of 50 msec, moved up at the maximum speed, and moved by the set amount of movement and then stopped. At this time, the acceleration time (acceleration) when the moving body 16 of the main spindle Z-axis moves is such that the feed motor 17 instantaneously exerts a large force so that it can be moved against the frictional force of the brake device 4. Is set to such a value.

  When a stop signal indicating that the spindle Z-axis feed motor 17 or the moving body 16 has been stopped is input from the spindle Z-axis servo control circuit 21 (S11), the rotation of the spindle rotation motor 11 of the spindle rotation shaft is stopped (S12). ).

  The machine tool of the present invention is not limited to the machine tool of the embodiment, and some examples have already been shown. However, various modifications can be made without departing from the object of the present invention and achieving the effects of the present invention. Can be modified. The balance device according to the embodiment has a configuration in which a counter balance weight is provided by the pressure of compressed air. However, the balance device is provided with a hydraulic cylinder type balance device configured to provide a counter balance weight by the pressure of pressurized oil. Applicable.

  The machine tool according to the present invention cuts a workpiece into a desired machining shape by moving the tool and the workpiece relative to each other in a synchronous control axis direction of two horizontal axes and one vertical axis by an axial feeder. Applicable to machine tools. In particular, the present invention is applied to a machine tool having a balance device that applies a counter balance weight to a gravity axis by the pressure of compressed air or pressurized oil. The machine tool according to the present invention ensures that when the pressure of compressed air or pressurized oil of the balance device is abnormal, the tool and the workpiece collide, and the tool is damaged or the workpiece is damaged. And contribute to improving the safety of machine tools.

It is a block diagram which shows the outline | summary of the whole structure in preferable embodiment of the machine tool of this invention. It is a block diagram which shows the structure of the control apparatus in preferable embodiment of the machine tool of this invention. It is a flowchart which shows operation | movement of the numerical control apparatus in preferable embodiment of the machine tool of this invention. It is a graph which shows an example of change of command speed to time in each control axis of a machine tool of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Machine main body 2 Control apparatus 3 Balance apparatus 4 Brake apparatus 5 Tool 6 Work piece 10 Numerical control apparatus 11 Spindle rotation motor 12 Moving body (column)
13, 15, 17 Feed motor 14 Moving body (table)
16 Moving body (slider)
20 motor control device 21 servo control circuit 22 power amplifier 30 solenoid valve control circuit 31 air cylinder 32 air supply device 33 pressure sensor 34 solenoid valve 41 brake body 42 solenoid valve 310 filter 320 oil mist filter 330 air regulator 340 high relief air regulator

Claims (3)

In a machine tool equipped with a balance device that applies a counter balance weight to the vertical axis by the pressure of compressed air or pressurized oil, avoiding interference between the tool and the workpiece when an abnormality occurs in the pressure of the balance device A machine tool having a control device that controls to move a movable body of a main shaft in a direction in which the tool moves away from the workpiece and operates a brake device provided on the vertical shaft. A machine tool which has a synchronous control axis in two horizontal axes and one vertical axis, and performs machining by moving a tool relative to a workpiece along a predetermined relative movement trajectory, which is compressed air or pressurized oil In a machine tool including a balance device that applies a counter balance weight to a vertical axis by the pressure of the tool, the tool moves on the predetermined relative movement locus and stops when an abnormality occurs in the pressure of the balance device. Thus, each movable body of the synchronous control shaft can be decelerated and stopped at a predetermined acceleration or deceleration time to avoid interference between the tool and the workpiece. A machine tool having a control device for controlling a moving body to move and for controlling a brake device provided on the vertical shaft. A machine tool which has a synchronous control axis in two horizontal axes and one vertical axis, and performs machining by moving a tool relative to a workpiece along a predetermined relative movement trajectory, which is compressed air or pressurized oil In a machine tool equipped with a balance device that applies a counter balance weight to the vertical axis by the pressure of the pressure, when an abnormality occurs in the pressure of the balance device, the speed at each position on the predetermined relative movement locus is a predetermined acceleration. Alternatively, all servo motors or all moving bodies of the synchronous control axes are stopped by controlling each servo motor based on a command including each position and the speed at each position that are gradually reduced in deceleration time and stopped. Based on a command to move the moving body of the spindle in a direction in which the tool and the workpiece are separated from each other by a predetermined distance that can avoid interference between the tool and the workpiece. Machine tool having a control device for controlling to operate the brake device provided on the vertical axis to control the spindle servo motor.

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