JP3818782B2 - Balance device for moving objects in machine tools - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a balance device for a moving body in a machine tool, and more particularly to a balance force with respect to the weight of a moving body such as a spindle device that is moved in a vertical direction by a feed drive motor such as a servo motor with respect to the machine tool body. The balance apparatus of the moving body in the machine tool which can reduce or reduce the load accompanying the weight bearing applied to the feed drive motor. In particular, the present invention provides not only a change in the weight of a moving body of a machine tool, for example, a tool or other attachment mounted on a spindle device, but also a relatively high acceleration or Even when moving in the vertical direction at high deceleration, the balance acting force for gravity balance is applied following the acceleration / deceleration feed movement, and the load of the vertical feed drive motor is constantly maintained at a low level. As a result, the present invention relates to a moving body balance device in a machine tool that can adopt a linear motor for direct connection as a feed driving motor.
[0002]
[Prior art]
Conventionally, a balance device that balances the weight of a moving body in a vertical direction in a machine tool is provided. For example, Japanese Patent Publication No. 6-37002 discloses a weight balance of a spindle head in a machine tool, an electric discharge machine, and other similar machining machines. A balancing device for control is disclosed. The balance device disclosed in Japanese Patent Publication No. 6-37002 generates a balance force by a cylinder device against a change in weight of a spindle head to which a machining tool is attached, and detects the position of the spindle head by a position detector. The position of the spindle head is controlled according to the deviation signal from the command value, and the pressure supplied to the cylinder device is controlled via the control valve according to the deviation signal. By performing pressure control according to the output of the deviation signal through the switching element in the state, the weight balance force for the spindle head is automatically adjusted according to the change in the weight of the spindle head, thereby improving the balance effect It is what has.
[0003]
[Problems to be solved by the invention]
However, the above-described conventional machine tool balance device balances the spindle head at the time of stopping under the condition that the weight change occurs due to the replacement of the machining tool, and the accurate balance when stopped at the command stop position. While force is required, finding the balance force during movement of the spindle head or during machining is a careful balance device. Therefore, for example, machining electrodes with high acceleration / deceleration such as jump operation in electric discharge machines. When a spindle device having a vertical movement is jumped up and down, it is impossible to obtain a position deviation signal, so that it is impossible to give a balance action to the spindle device. ing. For this reason, if this type of conventional balance device is used as it is, in order to balance the spindle device during high acceleration / deceleration motion, an extra drive output is anticipated in advance in consideration of the load applied to the feed drive motor. However, there is a disadvantage that the disadvantages in terms of economy cannot be overcome, such as the need to employ a large feed driving motor.
[0004]
Therefore, the object of the present invention is not only to obtain a balance force that follows the change in weight generated when the operation of the machine tool is interrupted, such as when the machining electrode mounted on the spindle device of the electric discharge machine is replaced. Even when the moving body that moves in a vertical direction moves up and down under a large acceleration / deceleration, the load for the weight support that the moving body's feed drive means bears is reduced. It is an object of the present invention to provide a moving body balance device in a machine tool capable of reducing the performance requirements for the feed driving means to the extent that only the driving force necessary for movement can be output.
[0005]
Another object of the present invention is to directly drive a drive motor such as a linear motor with a compact and limited output performance by eliminating a reduction gear and the like by directly connecting to a moving body and outputting a driving force. It is an object of the present invention to provide a moving body balance device in a machine tool that can be employed as a driving means for a moving body in a direction.
[0006]
[Means for Solving the Problems]
In view of the above-mentioned object, the present invention provides a servo control means for a moving body comprising a shaft means that can be moved in a vertical direction with respect to the machine tool body and a variable weight body that can be attached to the lower end of the shaft means. A fluid pressure obtained by connecting a balance device, which is provided so as to generate a balance acting force for reducing the weight of the movable body, to the shaft means when the feed means is moved in the vertical direction by the drive means that operates according to the feed command of A cylinder device, a fluid pressure storage means disposed in a fluid flow path connecting the fluid pressure cylinder device to a fluid pressure source, and a fluid flow path extending from the fluid pressure source to the cylinder device via the same storage pressure means A fluid regulator that controls the balance acting force applied to the moving body from the fluid pressure cylinder device in accordance with a command signal corresponding to the balance pressure calculated based on the drive output data of the drive means. It is obtained by constituting the balancing apparatus provided with the over data unit.
[0010]
  That is,According to the present invention, in the moving body balance device in a machine tool that generates a balance force against the weight of the moving body when the moving body is moved in the vertical direction in the liquid by the feed driving means,
  A fluid cylinder means coupled to the moving body for constantly acting a balancing fluid pressure against the weight of the moving body;
  Feed data detection means for detecting feed drive data such as feed speed data, position data, and drive current data of the feed drive means;
  A fluid pressure storage means provided between a predetermined fluid pressure source and the fluid cylinder means for absorbing fluctuations in the balancing fluid pressure of the fluid cylinder means;
  A balance for calculating a balance fluid pressure according to the amount of buoyancy action of the feed driving means in the liquid based on the position data of the feed driving means detected by the feed data detecting means during the feed movement of the moving body. Pressure calculating means;
  Provided between the fluid pressure source and the fluid pressure storage means, and controls the fluid supply pressure from the fluid pressure source to the fluid cylinder means to be the balancing fluid pressure calculated by the balance pressure calculating means. Fluid pressure control means;
  An apparatus for balancing a moving body in a machine tool is provided.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail with reference to the embodiment shown in the accompanying drawings. In the following, when a machine tool is formed of a sculpting electric discharge machine that performs electric discharge machining on a workpiece using a machining electrode, the electric discharge machining is performed. Description will be made on the basis of a balance device when the spindle device moving in the vertical direction (Z-axis direction) is a moving body and the present invention is applied to the weight balance of the moving body.
[0012]
FIG. 1 is a block diagram showing the configuration of the main part of a balance device that balances the weight of a spindle device in an electric discharge machine according to an embodiment of the present invention, and FIG. 2 shows the operation of the balance device shown in FIG. It is a flowchart to explain.
In FIG. 1, a spindle device 10 is shown as a vertical moving body in an electric discharge machine, and the spindle device 10 is provided with a spindle head 12 provided so as to be movable in a vertical direction with respect to the machine body of the electric discharge machine. A chuck 14 provided at the lower end of the spindle head 12 and a feed nut 16 provided on the spindle head 12 are provided. The feed nut 16 is coupled to an output shaft of a vertical axis (Z-axis) drive motor 20. The feed screw 18 is screw-engaged, and a feed movement in the vertical direction is given to the spindle head 12 via the feed nut 16 in accordance with the rotation of the feed screw 18. The Z-axis drive motor 20 includes various known servo motors, and the rotation amount of the output shaft can be detected by a rotation detector 22 including an encoder or the like. When a well-known servo-controlled linear motor is used as the Z-axis drive motor 20, the feed mechanism including the feed nut 16 and the feed screw 18 is eliminated and the output end of the linear motor is used as an appropriate part of the spindle head 12. By direct coupling, it is also possible to give the feed movement in the vertical direction directly to the spindle head 12 according to the linear movement of the output end of the linear motor in the vertical direction.
[0013]
A machining electrode 24 used for electric discharge machining is detachably attached to the lower end of the spindle device 10 via the chuck 14 and is mounted and installed on a work table 28 provided in a machining tank 26 by the machining electrode 24. A configuration for subjecting the workpiece W to electrical discharge machining is provided.
On the other hand, at the upper end of the spindle head 12 in the spindle apparatus 10, a cylinder apparatus 30 that balances the weight with respect to the total weight including the spindle head 12, the spindle apparatus 10 including the chuck 14, and the spindle mounted object such as the machining electrode 24. The cylinder device 30 includes a cylinder part 32 provided in the electric discharge machine body and a piston 34 provided movably in the cylinder part 32, the latter piston 34 being a piston rod. A cylinder chamber on the lower surface side of the piston 34 forms a fluid pressure chamber 32a that is directly connected to the spindle head 12 via 36. In this embodiment, the pressurized fluid is formed by pressurized air. Therefore, pressurized air is supplied to the fluid pressure chamber 32a from an air pressure source (fluid pressure source) 40, which will be described later, via an air line 38 to exert air pressure. A balance force for weight balance with respect to the spindle device 10 is generated. In the embodiment of the present invention, a livestock pressure air tank 42, which will be described later, and a fluid regulator 44 for controlling the flow rate of pressurized air and pressure are disposed in the air line 38. As the latter fluid regulator, a commercially available electro-pneumatic regulator, that is, a regulator element that controls the flow rate or fluid pressure of the fluid in response to an electrical command signal can be used.
[0014]
The air tank 42 is provided as a pressure storage tank having an appropriate volume capable of absorbing fluctuations in air pressure (insufficient pressure and excessive pressure) in the air duct 38 and the fluid pressure chamber 32a. Although it is possible to provide both a stock pressure function and a pressure fluctuation absorbing function by securing a large pipe volume, it is generally preferable to provide tank means. The fluid regulator 44 in the illustrated example is formed by an electropneumatic fluid regulator so that the pressure in the fluid pressure chamber 32a can be quickly adjusted in response to an electrical command signal, as will be described later.
[0015]
Now, an electric discharge machine is normally configured to be driven and controlled based on a control program such as an NC program. Therefore, machining data such as machining conditions suitable for individual workpieces W is stored in the control program. The machining data is input from the machining data input unit 50 such as CRT / MDI, and sent to the servo control means 54 via the feed control means 52. At this time, the servo control means 54 reads and interprets the control program and machining data, and for each feed drive that drives and controls the vertical feed movement of the spindle device 10 and the feed movement of the work table 28 according to the interpreted control program. A servo control unit (not shown) for sending control command data such as position and speed to the motor, and a drive current for each feed drive motor (Z-axis feed drive motor 20 etc.) based on the control command data Read the position data, speed data, command data such as drive current for each feed drive motor (Z-axis feed drive motor 20 etc.) via the servo amplifier section 56 and the servo amplifier section 56 that function to supply, The feed data detection unit 58 or the like that functions to detect is provided. In the case of this embodiment, the servo amplifier unit 56 is connected to the Z-axis drive motor 20 and its rotation detector 22 to supply a drive current to the motor 20 and to supply the Z-axis from the rotation detector 22. The position data and the feed speed data of the spindle device 10 are connected so as to be received via the rotation amount detection value of the drive motor 20.
[0016]
Further, a balance pressure calculating means 60 is provided connected to the feed data detecting section 58 of the servo control means 54, and the fluid pressure of the cylinder device 30 is momentarily based on the feed driving data obtained from the feed data detecting section 58 every moment. The balance pressure value required in the chamber 32a is calculated. The balance pressure value calculated by the balance pressure calculation means 60 is held by the pressure value holding / output means 62 and can be output to the fluid regulator 44. In other words, the pressure value holding / output means 62 sends an electrical command signal to the operating part of the fluid regulator 44, and the fluid regulator 44 causes the air pressure source 40 to pass through the air tank 42 and the air pipe 38, and the cylinder device 30. The air pressure supplied to the fluid pressure chamber 32a is controlled to achieve the weight balance of the spindle device 10.
[0017]
Next, the operation of the balance device that balances the weight with respect to the spindle device 10 described above will be described. Before that, various operation modes that the spindle device 10 that moves in advance in the vertical direction performs along with electric discharge machining. The necessity of weight balance will be described in advance.
First, when the operation stop mode of the electric discharge machine, that is, when the Z-axis drive motor 20 is stopped, the Z-axis drive motor 20 is in a non-output state. Even when the electric discharge machining action is stopped, the spindle device 10 has its own weight regardless of whether or not the machining electrode 24 is mounted. Therefore, a balance force against the own weight is given to the spindle device. 10 itself must stop at a predetermined original position. Therefore, the cylinder device 30 in the balance device needs to impart a balancing action to the spindle device 10 by supplying air pressure corresponding to the weight of the spindle device 10 to the fluid pressure chamber 32a.
[0018]
Further, a machining electrode 24 for electric discharge machining is mounted on the lower end of the spindle head 12 in the spindle device 10 via a chuck 14, and this machining electrode 24 can be variously selected according to the machining shape, dimensions, etc. of the workpiece W. They have different shapes and sizes, and therefore, the weight of the processing electrode 24 is also different from one another and is not constant. Accordingly, when the machining electrode 24 is exchanged with respect to the spindle head 12, the total weight of the spindle device 10 fluctuates. Therefore, the cylinder device 30 in the balance device has a balance force that balances the total weight of the spindle device 10 after the fluctuation. By generating this, the total weight of the spindle device 10 is reduced, the load for weight support applied to the Z-axis drive motor 20 is made zero, and only the driving load for feed movement in the Z-axis direction (vertical direction) is output. It is necessary to maintain a good condition.
[0019]
Further, in the process of replacing the machining electrode 24, since the machining electrode 24 is once removed from the lower end of the spindle head 12, the total weight of the spindle device 10 also decreases at this point. In such a case, it is necessary to adjust the air pressure in the fluid pressure chamber 32a of the cylinder device 30 to reduce the balance force for balancing. The total weight of the spindle device 10 is also reduced when the machining electrode 24 is consumed in the course of long-term use and the total weight of the spindle device 10 changes, or when the machining electrode 24 falls off the chuck 14 for some reason. In this case as well, the cylinder device 30 in the balance device must react quickly to achieve the weight balance.
[0020]
Further, in the electric discharge machine, the machining waste accumulated in the discharge gap between the machining electrode 24 and the workpiece W by causing the machining electrode 24 to jump in the vertical direction via the spindle device 10 in the electric discharge machining process of the workpiece W. Is removed from the discharge gap using the momentum of the machining liquid, and a process for promoting the electric discharge machining is performed. In the course of the jump operation of the machining electrode 24 and the spindle device 10, the piston 34 of the cylinder device 30 also jumps together. In such a jump operation process, the internal pressure of the fluid pressure chamber 32 a of the cylinder device 30 varies in response to the vertical movement of the piston 34. This means that the balance force for weight balancing on the spindle device 10 changes. Therefore, in this case, it is necessary to supply an adjustment air pressure that corrects and adjusts the change in balance force in synchronization with the timing of the jump operation.
[0021]
The balance device according to the present invention is configured to be able to give an accurate weight balance action to the spindle device 10 corresponding to each operation mode of the spindle device 10 described above. This will be described below with reference to the flowchart of FIG.
First, the balance force for balancing the weight generated by the cylinder device 30 in the balance device because the spindle device 10 is stopped at a predetermined original position as the electric discharge machine stops is the fluid pressure chamber of the cylinder device 30. The air pressure supplied to 32a may be maintained at a predetermined pressure value commensurate with its own weight of the spindle device 10, and in that case, the air pressure source 40, the air tank 42, the air line 38, and the fluid regulator 44 perform the above predetermined value. It is only necessary to supply and maintain the air pressure set to the pressure value to the fluid pressure chamber 32a of the cylinder device 30, and no special control action is required after the setting.
[0022]
Here, the above-described predetermined balance air pressure value required when the electric discharge machine is stopped is obtained when the holding force for stopping and holding the spindle device 10 at a predetermined original position is obtained from the output of the Z-axis drive motor 20 in advance. The required motor drive current is read from the feed data detector 58 to the balance pressure calculation means 60. In this case, since all the motor output is used for holding the spindle device 10 stopped, the motor output and the cylinder device 30 are used. The predetermined balance force can be calculated by calculating from the condition that the balance force acting on the spindle device 10 via the piston 34 is equal within the fluid pressure chamber 32a. By holding such a predetermined balance force via the pressure value holding / output means 62 and outputting it to the fluid regulator 44, the cylinder device 30 in the balance device allows the spindle device 10 itself to stop while the electric discharge machine is stopped. A balance force that balances the weight is generated, and the spindle device 10 is stopped and held at the original stop position. Further, such a predetermined air pressure value corresponding to the own weight of the spindle device 10 is stored as a balance reference value, for example, in a memory means included in the balance pressure calculation means 60 or the like.
[0023]
Now, when the operation mode in which the electric discharge machine is operated is entered, the machining electrode 24 is attached to the lower end of the spindle head 12 of the spindle device 10 via the chuck 14. At this time, the control mode shown in the flowchart of FIG. 2 operates. In other words, when the control mode is started, first, a determination step is performed to determine whether or not the main spindle device 10 has been changed (step 101). The mounting of the machining electrode 24 is equivalent to the replacement of the spindle mounting object. Therefore, the output for starting the clamp for operating the chuck 14 of the spindle device 10 to grip the machining electrode 24 is another control. By being supplied to the chuck 14 via the circuit, the chuck 14 grips the machining electrode 24 (step 102).
[0024]
Thereafter, a determination step (step 103) for determining whether or not the gripping (clamping) of the machining electrode 24 has been completed is performed via the control circuit, and if the completion of clamping is confirmed (Y process of step 103), the spindle device 10 has a total weight obtained by adding the weight of the processing electrode 24 together with its own weight. At this stage, the Z-axis drive motor 20 generates a holding output so that the spindle device 10 does not drop as the weight increases. An air pressure value for generating a balancing balance force is calculated based on the calculation of the holding output. If the completion of clamping is not confirmed in step 103 (N process of step 103), step 103 is repeated.
[0025]
  When the completion of clamping is confirmed (Y process of step 103), the drive current data of the Z-axis drive motor 20 is read from the servo amplifier unit 56 of the servo control means 54 to the feed data detection unit 58, and the drive current is obtained. A vertical output value (thrust value) output from the Z-axis drive motor 20 is calculated from the data (step 104).
  Next, the air pressure in the fluid pressure chamber 32a of the cylinder device 30 in the balance device is increased based on the predetermined balance pressure data for balancing the weight of the spindle device 10 described above. This amount of pressure increase can be easily calculated from the relationship between the output value of the Z-axis drive motor 20 and the motor output when the predetermined pressure value for own weight balance is determined. The internal pressure of the fluid pressure chamber 32a of the cylinder device 30 is adjusted based on the pressure increase thus calculated.. TransferThis pressure increase is the balance fluid pressure corresponding to the amount of change in the output value of the feed driving means calculated by the balance pressure calculating means when the weight of the moving body changes. Thus, when the weight balance with respect to the spindle device 10 on which the machining electrode 24 is mounted is achieved and the detected value of the drive current data of the Z-axis drive motor 20 becomes zero (Y process of step 105), the motor 20 is loaded with a weight support load. Therefore, it is assumed that the balance action by the balance device has been achieved, and the pressure value air pressure value calculated through the pressure value holding / output means 62 is output to the fluid regulator 44 and held. Thus, the balance state of the spindle device 10 is maintained (step 107).
[0026]
On the other hand, when the weight balance cannot be obtained even after the pressure increase (N process of step 105), the balance pressure calculating means 60 repeats the calculation of the balance setting pressure again (step 106) to achieve the weight balance. Calculate the required balance pressure value. Then, according to the calculated pressure value, a command is sent to the fluid regulator 44 via the pressure value holding / output means 62, and the air pressure supplied to the fluid pressure chamber 32a of the cylinder device 30 is adjusted to achieve a weight balance (step 107). ).
[0027]
In the process of detaching the machining electrode 24 from the chuck 14 of the spindle device 10, the grip 14 is released (unclamped) by the chuck 14, and the total weight of the spindle device 10 is reduced according to the completion of the unclamping (step 103). ), The balance air pressure supplied to the fluid pressure chamber 32a of the cylinder device 30 is set by performing the process from step 104 to step 107 in the same manner as described above.
[0028]
On the other hand, the operation of the balance device in the case where the spindle device 10 equipped with the machining electrode 24 performs a jump operation during the operation of the electric discharge machine will be described below.
When the spindle device 10 performs a jump operation from the time when it is in a balance state due to the weight balance operation generated by the cylinder device 30 in the balance device, the weight balance operation performed following the jump operation will be considered.
[0029]
First, the start time of the jump operation corresponds to a step (N process of step 101) in which the main spindle attachment (machining electrode 24) is not replaced in step 101 in the flowchart of the control action shown in FIG.
Therefore, in such a case, the spindle device 10 that has read the drive current data of the Z-axis drive motor 20 and the detection data of the rotation detector 22 by the feed data detection unit 58 from the servo amplifier unit 56 of the servo control means 54. Position data, velocity data, and the like are read out and detected.
[0030]
Then, the output value of the Z-axis drive motor 20 is calculated using the drive current data in the read and detected data. That is, the output value of the motor 20 can be easily calculated as a function of the drive current. Alternatively, the relationship between the output value of the Z-axis drive motor 20 and the drive current is stored in advance in a suitable memory means provided in the servo control means 54 as a table value, and obtained from the table value. good.
[0031]
  Thus, the output of the Z-axis drive motor 20value(Thrust value) Is completed (step 108), the output generated by the Z-axis drive motor 20 at each time point is obtained.
  On the other hand, based on the position data and speed data related to the spindle device 10, the force component in the vertical direction when the spindle device 10 is moved can be calculated according to the following calculation formula.
[0032]
      F = (M / g) × dv + Pμ + M (1)
    F: full force component, M: total weight of the spindle device 10 at that time, g: gravitational acceleration,
    dv: of the spindle device 10Acceleration during movement, Pμ: frictional force,
  The acceleration dv is obtained by differentiating the detected speed data v of the spindle device 10 with respect to time. Equation (1) is an equation of force, and represents that the total force component is the sum of three force components, ie, penetrating force, frictional force, and gravity.
  Step 109 shows a process of calculating the force component in the vertical direction of the spindle device 10 described above.
[0033]
  The total force component F obtained from the equation (1) is a force component relating to the spindle device 10 that is moving at a speed v by driving the Z-axis drive motor 20, and is obtained from this F first. By subtracting the output value of the Z-axis drive motor 20, the weight component of the spindle device 10 at that time can be obtained.Here, the weight component is a force component obtained by subtracting the output value (thrust value) of the Z-axis drive motor 20 when the spindle device 10 is stopped from the total force component when the spindle device 10 is moved.
  Next, it is determined whether or not the weight component of the spindle device 10 thus determined has changed with respect to the previously calculated weight component (step 110). That is, in the state where the machining electrode 24 is attached to the lower end of the spindle device 10, the machining electrode 24 does not suddenly wear out.ComponentNo change should occur. However, since the jump operation is a motion accompanied by high acceleration / deceleration, the piston 34 is integrated with the inside of the fluid pressure chamber 32a of the cylinder device 30 to perform vertical movement by high acceleration / deceleration. For this reason, a situation occurs in which the balance air pressure cannot change at a high speed in response to a change in the volume of the chamber 32a at a high speed inside the fluid pressure chamber 32a. That is, in the animal pressure air tank 42, it is impossible to keep the balance pressure inside the chamber 32a constant by adjusting the pressure change of the fluid pressure chamber 32a at a high speed via the air line 38.
[0034]
Under such circumstances, a change occurs in the weight component calculated from the force component of the spindle device 10 described above.
Therefore, when it is determined that such a weight component has changed (Y process of step 110), a balance pressure value corresponding to the weight component is calculated by the balance pressure calculating means 60 (step 111). Then, the balance pressure of the calculation result is output as a command value to the fluid regulator 44 via the pressure value holding / output means 62, and the air flow rate supplied to the fluid pressure chamber 32 a of the cylinder device 30 via the air tank 42 by the fluid regulator 44. Alternatively, a predetermined balance pressure is generated by controlling the air pressure (step 112).
[0035]
  Weight of spindle device 10 at step 110ComponentWhen determining whether there is a change, weightComponentWhen there is no change (N process of step 110), in the fluid pressure chamber 32a of the cylinder device 30 in the balance device, the pressure fluctuation in the chamber 32a follows the vertical movement of the piston 34 and the air tank 42 has a large fluctuation. It is absorbed by the pressure capacity, and the process of balance pressure calculation or the like is not executed on the assumption that an appropriate balance action is performed, and the process again proceeds to the spindle mounted article replacement determination step in Step 101.
[0036]
  Also, the weight of the spindle device 10 performed in step 110.ComponentIn the process of determining the change, the machining electrode 24 is immersed in the machining liquid in the machining tank 26 to perform a machining operation, for example, as in an electric discharge machine, so in the case of a large machining electrode 24 or the like, Weight due to buoyancy effectComponentIt is necessary to consider changes. Such a buoyancy effect is related to the immersion depth of the machining electrode 24 in the machining liquid, and accordingly, a buoyancy proportional to the position of the spindle device 10 in the Z-axis direction is generated. In such a case, the buoyancy action amount is obtained by obtaining the position data of the spindle device 10 from the feed data detection unit 58, and the weight of the spindle device 10 based on such buoyancy action amount.ComponentChanges can be taken into account.
[0037]
  The balance pressure calculation performed in the balance pressure calculation means 60 is based on a predetermined balance pressure value obtained in advance for the spindle device 10 as a reference value, and the relationship with the output change of the Z-axis drive motor 20 is experimentally determined. If required, the balance pressure can be easily calculated.
  In the above description, the balance device that balances the weight of the spindle device that moves in accordance with the drive of the Z-axis drive motor in the vertical axis (Z-axis) direction of the electric discharge machine as the balance device of the moving body of the machine tool is implemented. Although explained as a form, vertical feed drive is also obtained by applying the present invention to the balance effect of the spindle device in the vertical direction in a punch press machine, a vertical milling machine, a vertical machining center, etc. It is possible to reduce the load on the motor.The time when the weight of the moving body is changed is when the electrode is replaced in the electric discharge machine and when the tool is replaced in the machining center.
[0038]
【The invention's effect】
As described above, the present invention has been described based on the representative embodiments. However, according to the present invention, as a balance device that performs weight balance of a moving body that is fed and moved in a vertical direction in a machine tool, simply to the lower end of the moving body. The balance force for balancing is adjusted and controlled in response to the weight change due to the attachment and detachment of the attachments to reduce the weight bearing load on the vertical feed drive motor, and the motor output is purely for vertical feed movement In addition to being able to obtain an appropriate and effective balance action, it is always possible to use a feed drive motor even when the moving body moves up and down with high acceleration / deceleration such as jumping movement. It is sufficient that the output for driving the vertical movement of high acceleration / deceleration can be generated by reducing the load for weight balance applied. Therefore, the vertical feed motor is reduced in size, and consequently the machine tool. It can allow realizing energy saving operation of the drive motor.
[0039]
In addition, it is possible to reduce the heat generated by the drive motor of the machine tool by reducing the size of the vertical feed drive motor, thus reducing the heat transfer to the machine tool body as much as possible. In addition, since it is possible to prevent deterioration of machining accuracy due to thermal factors, it contributes to improvement of workpiece machining accuracy.
In addition, since a relatively small output motor can be used as the vertical feed motor, it is possible to form a vertical feed motor using a linear motor. The mechanism can be simplified by directly connecting the linear motor and the moving body, and therefore contributes to the miniaturization of the machine tool body itself.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main configuration of a balance device that performs weight balance of a spindle device in an electric discharge machine according to an embodiment of the present invention.
FIG. 2 is a flowchart for explaining the operation of the balance device shown in FIG. 1;
[Explanation of symbols]
10. Spindle device
20 ... Z-axis drive motor
30 ... Cylinder device
40 ... Pneumatic source
42 ... Air tank
44 ... Fluid regulator
58 ... Feed data detector
60. Balance pressure calculation means
62 ... Pressure value holding / output means

Claims (1)

In the balance device for a moving body in a machine tool that generates a balance force against the weight of the moving body when the moving body is moved in the vertical direction in the liquid by the feed driving means,
A fluid cylinder means coupled to the moving body for constantly acting a balancing fluid pressure against the weight of the moving body;
Feed data detection means for detecting feed drive data such as feed speed data, position data, and drive current data of the feed drive means;
A fluid pressure storage means provided between a predetermined fluid pressure source and the fluid cylinder means for absorbing fluctuations in the balancing fluid pressure of the fluid cylinder means;
A balance for calculating a balance fluid pressure according to the amount of buoyancy action of the feed driving means in the liquid based on the position data of the feed driving means detected by the feed data detecting means during the feed movement of the moving body. Pressure calculating means;
Provided between the fluid pressure source and the fluid pressure storage means, and controls the fluid supply pressure from the fluid pressure source to the fluid cylinder means to be the balancing fluid pressure calculated by the balance pressure calculating means. Fluid pressure control means;
An apparatus for balancing a moving body in a machine tool, comprising:

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