JP2005138189A - Feed mechanism for mechanical structure having counter balance device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a feed mechanism for a mechanical structure cooling a counter air balancer of the mechanical structure which frequently, severely, highly responsively, and vertically moves up and down at high speed by a linear motor without adding a special device or the like. <P>SOLUTION: The feed mechanism has the following constitution. An air pressure chamber of an air balancer 15, to which air pressure for supporting the self-weight of the mechanical structure is introduced, is connected to an air pressure source via an air regulator 21 with a relief valve, which is regulated to the support air pressure, and intake throttle valves 22, 23 which limit the inflow of pressure air and exhaust by opening. An air chamber on the side opposite to the air pressure chamber is sealed. Conduits 24, 25 for flowing in and discharging air are provided. The intake throttle valve, which limits the inflow of outside air and exhausts by opening, is provided to the conduits. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a driven machine structure such as a main shaft that reciprocates in the vertical direction of a machine tool such as a die-sinking electric discharge machine or a machining center, or an axis slider that supports a horizontal main shaft and moves in a reciprocating direction in the vertical direction. The present invention relates to a feed mechanism for a machine structure having a counter balance device for supporting its own weight, and can be applied to an XY stage device and a precision measuring device of a semiconductor manufacturing apparatus in addition to the above-mentioned various machine tools. The structure is useful when applied to a structure that performs high-speed and high-speed travel axis movement with high response, such as driving with a linear motor.

  A driven machine such as a shaft slider that reciprocates in a direction including a vertical or vertical component while supporting a quill, a main shaft, or a horizontal main shaft that reciprocally moves in a direction including a vertical component in a movable part of a machine tool. In the case of a device that moves the structure using a so-called linear motor, the acceleration / deceleration acceleration is set to a large value of gravitational acceleration of 1.0 G or more in order to realize high-speed driving with high response. Therefore, a weight or the like cannot be used as a counter balance device that lifts and balances the mechanical structure against gravity, and an air balancer that uses air pressure in which the piston and the cylinder reciprocate relatively moves. It has been used in a highly responsive state directly connected by a rigid body without using a wire or the like (see, for example, Patent Documents 1-4).

  As a specific example, the case of a die-sinking electric discharge machine will be described with reference to FIGS. 4-8. FIG. 4 is a perspective view showing the overall configuration of the die-sinking electric discharge machine equipped with a feeding device driven by such a linear motor. In the figure, 101 is a bed, 102 is a column erected on the rear side or upper surface of the bed 101, 103 is a saddle provided on the bed 101 on the front surface of the column 102 so as to be movable in a horizontal uniaxial (Y-axis) direction, 104 Is a table provided on the saddle 103 so as to be movable in another horizontal uniaxial (X-axis) direction, 105 is a processing tank located on the front side of the column 102 provided on the table 104, and a workpiece not shown is attached, A processing table is provided that is disposed opposite to the processing electrode 106 in a state immersed in the processing liquid.

Reference numeral 107 denotes a processing spindle frame attached to a column front surface 102A extending to the processing tank 105 side at the top of the column 102, and is a hollow columnar body as a whole, and has a substantially square pillar shape having a mounting device 108A for the processing electrode 106 at the lower end. The Z-axis quill 108 is enclosed and held by a linear guide device 109 provided between the rear surface of the quill and the front surface of the column or the inner surface of the machining spindle frame so as to be linearly movable by driving in the vertical direction. 110A and 110B oppose each other through a minute gap with a magnet plate of a permanent magnet piece (not shown) arranged in a predetermined number along the moving direction on each of the opposing side surfaces perpendicular to the vertical direction of the Z-axis quill 108. In this way, a pair of electromagnet devices comprising yokes and wound exciting coils provided on both side surfaces of the machining spindle frame 107, that is, a so-called linear motor excitation stator, a Z-axis quill 108 with a permanent magnet attached thereto is a linear motor. It is moved as a mover of the magnet plate.

5 is a sectional plan view of the processing spindle frame 107 along the line AA in FIG. 4, FIG. 6 is a left side view taken along the line BB, and FIG. 7 is a sectional view along the line CC. In the front view, as shown in the plan view of FIG. 5, the machining spindle frame 107 has a U-shaped cross section in this example. Therefore, in the drawing, for example, the rail 109A of the linear guide device 109 is shown. For example, in the case of a cross-sectional mouth shape, a linear scale or the like for detecting the position of the rail 109A or the Z-axis quill 108 is provided on the inner wall surface of the machining spindle frame 107 or the like. It is provided at another position. Further, in the case of the illustrated example, a part of the front surface of the machining spindle frame 107 can be opened and closed, and interior, assembly, and adjustment are possible.

The Z-axis quill 108 is driven as a mover of a linear motor having a configuration described later, and has a high response and a high speed, particularly in the case of an electrode jump operation, preferably in both reciprocations, and at the time of proximity return after at least a long stroke jump. It is desirable to make it lighter so that the acceleration can be accelerated and move at a high acceleration of 1G or more. In the illustrated case, the rectangular Z-shaped quill 108 has permanent magnet pieces 111A and 111B on both sides. Since it is necessary to provide a line by bonding or the like in the moving direction, a through hole 108B having a desired inner diameter is formed at the axial center of the rectangular columnar body. It is also possible to adopt a framework configuration such as 3 or B.

However, more preferably, the entire columnar Z-axis quill 108 having the through-hole 108B is made of an integrated ceramic sintered compact (density, about one-third of iron), for example, an oxide-based ceramic, or a non-oxide. Of these, ceramics having Si3N4 as a main component are particularly preferable. If ceramics is used for the Z-axis quill 108 as described above, a good magnetic circuit is not formed between the permanent magnet pieces 111A and 111B attached as the mover of the linear motor. In this case, permanent magnet pieces 111A and 111B are fixedly attached to both sides of the ceramic Z-axis quill 108 after attaching magnetic plates 8C made of a soft magnetic material such as an iron plate. If the Z-axis quill 108 is made of ceramics and is made of an integrated hollow columnar body, it is lightweight, so it has low inertia, high control responsiveness, and little expansion and deformation due to heat. A feed mechanism that enables If the Z-axis quill 108 is made of steel and is an integral hollow columnar body, the cross-sectional dimension can be minimized, so that a compact feeding mechanism in which the processing spindle is not bulky can be obtained.

Thus, in the illustrated example, the linear guide device 109 that guides the vertical movement of the Z-axis quill 108 includes two linear motion ball (or roller) bearing rails 109A at predetermined intervals. Two parallel bearing blocks 9B and 9B are attached to the Z-axis quill 108 at a predetermined interval in the vertical direction, and are attached to the column front surface 102A in parallel with each other. It is assembled and assembled.

110A and 110B are arranged so as to face each other with a small gap on both side surfaces of the Z-axis quill 108 to which the permanent magnet pieces 111A and 111B are attached in the vertical movement direction, respectively. Excitation stators for linear motors attached to the portions 107B and 107C by mounting plates 112A and 112B, respectively. The excitation stators 110A and 110B are composed of yokes 110AY and 110BY and excitation coils 110AC and 110BC wound around the comb teeth of the yoke, respectively. A staggered hole through which the cooling pipes 114 </ b> A and 114 </ b> B through which the cooling fluid flows is provided in the laminated portion on the base side.

In order to reduce cogging, the linear motor in the case of the illustrated configuration includes a mover including a Z-axis quill 108 in which permanent magnet pieces 111A and 111B are attached in two rows on one side, a yoke 110AY and 110BY, and an exciting coil 110AC. The linear motor type is a permanent magnet movable linear AC synchronous motor (LSM), and two excitation coils 110AC and 110BC are provided on each side according to the magnet single row. However, it is good also considering the magnet piece row as one row and the exciting coil as one piece. Further, since the linear AC synchronous motor (LSM) has a three-phase coil current of the linear DC motor (LDM), the linear DC motor (LDM) can be used as the linear motor. In addition, an exciting coil movable linear motor in which the relationship between fixing and moving the permanent magnet piece array and the exciting coil described above is reversed from that shown in the figure can be configured and used according to the purpose.

As described above, the linear motor is formed on both the left and right side surfaces perpendicular to the moving direction of the structure such as the Z-axis quill 108, so that the linear motor between the mover and the stator on both the left and right sides of the quill 108 is provided. The magnetic attraction force of the Z-axis quill 108 is improved by balancing the magnetic attractive forces of the Z-axis quill 108 and canceling the horizontal and horizontal forces. Further, push screws distributed and provided on the back plate surfaces of the mounting plates 112A and 112B of the yokes 110AY and 110BY so that the magnetic attractive forces on the left and right side surfaces of the quill 108 can be balanced and canceled. By adjusting the inclination of the yokes 110AY and 110BY and / or forward / backward positioning with a pull screw, the gap between the plate surface of the mover-side permanent magnet pieces 111A and 111B and the yokes 110AY and 110BY is entirely the same on both the left and right sides. In the illustrated case, the gap is adjusted so that the magnetic attractive forces of the left and right linear motors are equal. Of course, after the adjustment setting, the push screw and the pull screw may be fixed with a fixing agent.

Reference numeral 113 denotes a linear scale that detects a linear movement position of the Z-axis quill 108 with respect to the column 102A or the spindle frame 107. In the illustrated case, the scale 113A is on the front surface of the Z-axis quill 108 and the front inner surface of the machining spindle frame 107 facing this. The sensor 113B is attached to. The linear scale feeds back the detected position signal to a drive device to which a movement position command signal is given from the NC control device, and the drive device outputs an operation signal for control to the excitation coils 110AC and 110BC.

In the above configuration, there is no configuration in which the weight of the Z-axis quill 108 having the electrode mounting device 108A at the lower end is lifted against the gravity, and when the device is driven, an upward controlled thrust is applied by the linear motor. However, in this case, power consumption corresponding to this thrust is large, and there arises a cooling problem of the electromagnetic stator composed of the yoke and the exciting coil. In order to cope with such a case, an air balancer 115 including a cylinder 115A, a piston 115B, a rod 115C, a valve (not shown), a pipe, and the like is used as means for suspending the Z-axis quill from the column 102 or the processing spindle frame 107 side. It is good to provide. The air balancer 115 fixes one of the cylinder 115A or the rod 115C to one of the column 102 (frame body 107) or the Z-axis quill 108, and connects or fixes the other to each other to fix the quill 108 to the column 102 (or It can be suspended from the spindle frame 107). In addition, in the case of the illustrated example, the cylinder 115A of the air balancer 115 is coaxially inserted into the through hole 108B of the quill 108 in order to achieve a well-balanced and space-saving state, and is connected to the quill 108 at the upper flange portion 115D. The upper end of the rod 115C is connected and fixed to a fixing portion such as the column 102 via the connecting member 116. With such a configuration, the vertical length of the Z-axis is shortened, and the machining spindle device becomes compact.

As shown in FIG. 8, the air balancer 115 is supplied with compressed air of about 6 kgf / cm ² from an air pressure source 118 such as a compressor. Compressed air is introduced into the upper chamber 115RU of the cylinder 115A through the air regulator 120 of 5 kgf / cm ² and the high relief regulator 121 of the setting of about 2.5 kgf / cm ^{2 to} 4.5 kgf / cm ² . The lower chamber 115RD is substantially opened to the atmospheric pressure. The set pressure of the high relief regulator 121 is set according to the total weight of the quill 108 and the electrode 106. When compressed air is supplied in this way, both the left and right linear motors operate to control the Z axis quill 108 as a mover to feed and position the air balancer 115, the Z axis quill 108 and the cylinder 115A. And hang them together. Here, when the quill 108 is lowered, the air pressure in the upper chamber 115RU of the cylinder 115A tends to increase, but since the pressure is controlled by the relief valve of the high relief regulator 121, the air in the upper chamber 115RU is discharged. That is, it is relieved and returns to a constant pressure. On the other hand, when the quill 108 rises, the high relief regulator 121 operates so that air is rapidly sent to the upper chamber 115RU to be depressurized to become a constant pressure. In this way, by applying a balance thrust that balances the weight of the Z-axis quill 108, it is possible to control the movement of the Z-axis quill 108 with low inertia (low moment of inertia) and high-speed response. It enables shaft static control that is close to no load during static control.

In summary, the general configuration of the spindle device of the preferred EDM machine provided with the linear motor as the positioning control feed means for the Z-axis machining spindle is the Z-axis machining spindle that is mounted and held on the column or the X-axis moving body. A Z-axis quill provided with an electrode mounting device at the lower end is linearly reciprocated in the Z-axis direction to a Z-axis machining spindle frame that coaxially surrounds the Z-axis quill by a linear guide device and an air balancer. A magnet plate made of a soft magnetic material in which permanent magnet pieces are arranged in a moving direction and an electromagnet made of a yoke iron core and a wound exciting coil are arranged opposite to each other with a gap therebetween. A linear motor is provided between opposite sides of the Z-axis quill and both side walls of the Z-axis machining spindle frame facing the opposite sides, and the Z-axis quill of the Z-axis quill with respect to the Z-axis machining spindle frame is provided. Relative movement position The detection feedback signal from the linear position detecting device mounted therebetween so as to output would say that so as to control the exciting coil current of the linear motor.

According to such a die-sinking electric discharge machine in which the Z-axis spindle is driven and controlled by a linear motor, a conventional rotary servo motor can be accurately controlled with high response to a minute machining gap. Compared to the servo feed control system that uses a combination of a screw and a ball screw, the machining gap distance can be maintained more properly than usual, and the machining time can be shortened to about 1/2 to 1/6 with high accuracy. Jumping is possible, and deep hole machining with an electrode that is long in the machining direction and has a small cross-sectional area, which is called rib machining, is not possible in the past without ejecting the machining fluid from the electrode to the machining gap. As a result, it is possible to process to a certain depth, and the revolutionary effect that the required processing time is greatly reduced is being confirmed.

9 and 10 are explanatory diagrams of the same configuration example as in FIG. 6 described above, and the same or equivalent functions as those shown in FIGS. The latter 100 is added and displayed. 4 to 8, the air balancer 115 for lifting the weight of the Z-axis quill 108 against its gravity is housed concentrically in the hollow portion of the quill 108, and is integrally coupled. While the shaft machining main shaft has a short overall length and is compact, the above-described ones in FIGS. 9 and 10 both have the piston rod 215C of the air balancer 215 housed in the hollow portion of the Z-axis quill 208. In a configuration in which the quill 208 is suspended by being fixedly attached to the connecting member 216 for fixing the upper end of the upper end to the fixed side or the top plate material 216A supported by the connecting member 216, according to such a configuration, Although the overall length of the Z-axis machining spindle is increased, the inertial mass of the moving quill is reduced, which is considered to be a practical configuration. In the other figures, 266 is fixed to the upper end of the cylinder cylinder 215A, and the fall prevention brake device for the Z-axis quill 208 clamps the piston rod 215C when necessary, 245 is the machining spindle frame of the Z-axis quill 208 Upper stoppers 246 for restricting the lowering limit with respect to the body 207 are similarly lower stoppers for restricting the upper limit.

  Next, a conventional example of a metal cutting machine tool will be described with reference to FIG. 11. Problems such as the above in a machining spindle such as a quill that is axially moved by a linear motor of a die-sinking electric discharge machine. Of course, the same applies to a Z-axis machining spindle such as a machining center for machining, etc. Also, a slider that reciprocally moves in the vertical direction while supporting the machining spindle as described above horizontally. The same applies to, for example, the case of FIG. 11 in which the weight of the driven machine structure is supported by the air balancer.

  In FIG. 11, reference numeral 301 denotes a machine tool main body, which is provided with a machining table (not shown) in front of a vertical bed 302, and three axes (Z) orthogonal to a workpiece 303 placed and fixed on the machining table (Z (Axis, Y-axis, Z-axis) are moved and positioned to perform processing.

  A column-shaped X slide 304 is supported on the front surface of the vertical bed 302 so as to be movable in the X axis direction, and a Y slide 305 is supported on the X slide 304 so as to be movable in the Y axis direction (vertical direction). ing. The Y slide 305 is supported by a slide 306 that constitutes a ram that rotatably supports the main shaft 303 on which a tool (not shown) is mounted, and is movably supported in the Z-axis direction. Is formed of a light metal material such as an aluminum alloy. Counter balance cylinders 340 are disposed on the left and right sides of the X slide 304, respectively, to reduce the couple acting on the Y slide 305.

  The vertical bed 302 is substantially L-shaped when viewed from the left side, and has a rectangular frame shape when viewed from the front. A rail 310 extending in the X-axis direction is disposed at the front lower portion of the upper frame portion 302a of the vertical bed 302, and two rails 310 extending in the X-axis direction are provided on the upper surface of the lower frame portion 302b protruding forward. , 310 are arranged in parallel to each other.

  The X slide has a vertically long rectangular frame shape in a front view in which upper end portions of the left and right vertical frames 304a and 304b are joined by an upper frame portion 304c and lower end portions are joined by a frame portion 304d. A relief recess 330 is formed in the front portion of the portion 304c. In addition, two guides 311 that are slidably engaged with the rail 310 of the upper frame portion 302a are arranged on the back surface of the upper frame portion 304 with a space therebetween, and the lower frame is provided at the four corners on the bottom surface of the lower frame portion 304d. A guide 311 is provided in sliding contact with the rails 310 and 310 on the upper surface of the portion 302b.

  Between the upper frame portion 302a of the vertical bed 302 and the lower rail 310 of the lower frame portion 302b, the stators 321 and 321 of the linear motor 320 are arranged in parallel to the rail 310, respectively. Movers 322 and 322 of the linear motor 320 are arranged and fixed on the back surface of the upper frame portion 304c and the bottom surface of the lower frame portion 304b, respectively. In addition, rails 331 are provided on the front surfaces of the vertical frame portions 304a and 304b so as to slide and engage with guides 334 provided on the Y slide 305 to guide the Y slide 305 about the shaft. 306 has a cylindrical box frame portion 315 extending rearward in the shape of a cross-sectional mouth having a rectangular through hole 315a inserted therethrough, and is fixed to the front surface of the box frame portion 315 so as to make a right angle thereto. The slide frame portion 333 is provided.

  The slide frame portion 333 has U-shaped protrusions forming left and right motor holding walls on the back surface, and the left and right motor holding walls are motors on the side surfaces of the vertical frame portions 304a and 304b facing each other in the X-axis direction. The Y slide 305 is moved up and down in the Y-axis direction with respect to the X slide 304 by a linear motor 320 which is opposed to the holding surface and includes a moving wall 321 of the holding wall and a stator 322 of the holding surface.

The Z slide 306 is configured by inserting and holding the main shaft 303 in the axial center of a rectangular parallelepiped slide main body that is inserted into the through hole 315a of the box frame portion 315 so as to be able to advance and retreat. On the left and right outer surfaces of the slide body of the Z slide 306, a mover and a stator having the same structure as that of the mover 322 and the stator 321 are arranged so as to face each other with a predetermined gap therebetween. 306 forward and backward positioning movement is enabled.
JP 2000-225526 A JP 2002-346843 A JP 09-262727 A Japanese Patent Laid-Open No. 10-263960

  In the case of the above-mentioned Die-sinker EDM, depending on the purpose of machining and the shape of machining, in addition to various positioning feeds, to maintain a good gap state of the micro machining gap between the electrode and workpiece Servo-controlled feed operation with a minute stroke and periodic or gap state detection and discrimination for discharge of generated machining waste from the above machining gap, moving as fast as possible in the opposite direction for electrode jump operation A large stroke feed operation is frequently performed.

  FIGS. 12 and 13 show the quill 108 ascending feed (FIG. 12) and the quill 108 descending feed (FIG. 12) during the machining electrode jumping operation of the die-sinking electric discharge machine using the linear motor as the feed drive source as described above. FIG. 13) illustrates the operation state of the air balancer 115 inside the air balancer 115. When the electrode jump operation is started and the quill 108 is lifted and fed by the linear motor, the upper chamber 115RU of the cylinder 115A tends to be depressurized. However, since the high relief regulator 121 is immediately actuated to send pressurized air, and the air pressure in the upper chamber 115RU is controlled at high speed so as to maintain the air pressure adjusted and set in the relief valve of the regulator 121. Heat generation due to friction between 115B and the cylinder 115A is limited. In addition to such frictional heat generation, a so-called adiabatic compression state is generated in which the air pressure that has seemed to be reduced due to the rise in the upper chamber 115RU is compressed in a short time until it slightly exceeds the set pressure of the relief valve of the regulator 121. It will generate heat.

  The heat generated by the friction of the air balancer 115 and other causes as described above is accumulated as the operating time elapses, and the temperature around the cylinder 115 rises, and the portion requiring accuracy is required. There was a problem that the processing accuracy was lowered due to heating of the steel. In particular, the jump setting conditions for die-sinking electric discharge machining by the above-mentioned die-sinking electric discharge machine are, for example, shortening the discharge time between jumps as the depth of the machining hole becomes deeper as the machining time elapses, and setting the jump cycle. Many of the jump conditions are set to a high load state, such as shortening and making frequent jumps, increasing the jump lifting stroke, and increasing the moving speed, and heat generation and heating become intense. The accuracy was impaired.

  FIG. 14 shows a regulator 21 relief valve when electric discharge machining is performed while performing the jump movement which is a reciprocating movement close to the workpiece, using the above-described die-sinking electric discharge machine installed in a temperature-controlled room. In the measured temperature characteristic diagram of the experimental example for predicting the change state of the exhaust gas temperature, the temperature of the piston rod 115B of the air balancer 115, and the temperature at the upper end and the lower end of the quill 108, the jump is performed approximately once per second. As described above, the separation rising time (UP) of the machining spindle by the linear motor is set to about 250 ms, and the time (DN) of machining close to the lowering is set to about 400 ms, and the feed speed (JS) during the jump by the linear motor is set. : M / min) is set to 1, 5, 10, 25, and 36, respectively, and the operation is performed for 20 minutes each, and the jump speed (JS) is 2 Since the temperature of each part around the air balancer 115 rises in a short time when the speed is as high as about m / min or more, and the temperature rise of each part is different from each other, the quill 108, the air balancer 115, etc. It is clear that the trajectory and position set as a structure cannot be maintained and cannot be moved precisely.

  Of course, it is conceivable to take cooling means by any means for the heat generation and heating of the air balancer 115 and the like, but in the case of the above-described configuration example, the cylinder 115A and the quill 108 have a high speed. However, since the quill 108 moves with respect to the fixed cylinder 115A even when the cylinder 115A is fixed, cooling is generally difficult and air cooling by a cooling fan or the like is attempted. When the temperature of the outside air is changed in some cases, the cooling due to the introduction of the air has a problem that, as a result of increasing the dependency of the main shaft portion such as the quill 108 on the outside air temperature, another form of thermal deformation is caused.

  In the case of the machine tool such as the machining center of FIG. 11 described above, the Y slide 305 that holds the machining spindle slide 306 parallel to one horizontal axis is moved vertically with respect to the X slide (base body) 304 by a linear motor. A pair of air balancers 340 are provided as counter balancers for holding the own weight of the Y slide 305 and its integrated body (mechanical structure) with respect to the X slide 304, and in this case, the cylinder is provided in the cylinder. Since the side is the fixed (base) side, the pressure gas from the regulator is introduced and held in the lower chamber of the air balancer 340, but substantially the same as described with reference to FIGS. The heat generation problem of the same air balancer was a problem that had to be solved in the same manner as in the case of the above-described die-sinking electric discharge machine.

  Therefore, the present invention is a devised device that does not require a special device or the like for the counter air balancer of the mechanical structure that moves frequently in the vertical direction with high response, high speed, and intensely by the linear motor as described above. It is proposed that it can be cooled by taking

The object of the present invention described above is (1) a mechanical structure feeding mechanism held on a base body so as to be reciprocally movable in a vertical direction,
A gas pressure balancer in which a piston and a cylinder that support the mechanical structure with a gas pressure relative to the base move relatively reciprocally; and a linear motor that drives the mechanical structure with respect to the base to move the shaft. Prepared,
The gas pressure chamber of the gas pressure balancer into which the pressure gas that supports the weight of the mechanical structure is introduced includes the gas pressure source, the gas pressure regulator with a relief valve, and the inflow of the pressure gas from the gas pressure source through the regulator. Restricted exhaust is achieved by providing a mechanical structure feed mechanism having a counter balance device connected via an open intake throttle valve.

The object of the present invention described above is (2) a mechanical structure feeding mechanism provided to the base body so as to be reciprocally movable in the vertical direction.
An air balancer in which a piston and a cylinder that support the weight of the mechanical structure with respect to the base by air pressure are reciprocally moved; a linear motor that drives the mechanical structure relative to the base and moves the shaft; A position detection device that detects a linear movement position of the mechanical structure with respect to the base, and a drive control device that outputs a drive current to the linear motor while receiving feedback of a detection position signal from the position detection device in response to a position command from the control device And
The air chamber of the air balancer into which the air pressure that supports the weight of the mechanical structure is introduced is an air pressure source, an air regulator with a relief valve that is adjusted to the support air pressure, the inflow of pressure air is restricted, and the exhaust is open. This is achieved by providing a feed mechanism of a mechanical structure having a counter balance device connected via an intake throttle valve.

  The object of the present invention is as follows. (3) The air chamber on the side opposite to the air balancer supporting air pressure chamber is sealed, and a conduit for inflowing and exhausting air is provided. This is achieved by providing a feed mechanism for a mechanical structure having the counter balance device according to the above (1) or (2), which is provided with an open intake throttle valve.

  The object of the present invention is as follows. (4) The counter balance device according to (1), (2) or (3), wherein the intake throttle valve is a parallel connection body of a check valve and a throttle valve. This is achieved by providing a feed mechanism for a mechanical structure having the same.

  Further, the object of the present invention is as follows: (5) The machine structure is a Z-axis main shaft that reciprocally moves in the vertical direction of the machine tool (1), (2), (3) or (4). This is achieved by providing a feed mechanism for a mechanical structure having the counter balance device described.

  The object of the present invention is as follows. (6) The machine structure is a Z-axis slider that holds the horizontal main shaft of the machine tool and reciprocates in the vertical direction. (1), (2), (3 ) Or (4) to achieve the feed mechanism of the mechanical structure having the counter balance device.

  The invention according to claim 1 is a gas pressure counter balancer to which the means of the cooling principle of the present invention is added to the minimum, and the inflow and the exhaust to the gas pressure chamber of the cylinder into which the pressure gas for counterbalance flows, An intake throttle valve that prevents the inflow and opens the exhaust is provided, and adiabatic expansion is generated, so that heat generated mainly by friction of the cylinder and heat generated by adiabatic compression caused by delay of the relief valve can be cooled from the inside. .

  The invention according to claim 2 is obtained by adding a mode in which the mechanical structure supported by the air balancer is driven and controlled by a linear motor to the invention of claim 1. Are the same.

  The invention according to claim 3 described in the cited form with respect to each of the inventions of claims 1 and 2 applies the cooling principle adopted in the present invention evenly to the counter air balancer. A gas chamber on the opposite side of the cylinder's gas pressure chamber from which outside air flows in and out also prevents the outside air from flowing in and provides an intake throttle valve that opens the exhaust, thereby causing adiabatic expansion in the upper and lower cylinder chambers. This is extremely useful because it can cool the heat generated by friction from both sides in a well-balanced manner.

  The invention described in claim 4 is the invention described with reference to each of the inventions described in claim 1, 2 or 3, wherein the pressure gas to the gas pressure chamber in each of the inventions of claim 1-3 Specifically, the thing that restricts each inflow of ambient air into the air chamber is specified as “throttle valve”, and the thing that opens the gas discharge from the gas pressure chamber or air chamber is specifically specified as “check valve” As a result, the object and effect of the invention can be reliably achieved.

  The invention described in claim 5 is the invention described with reference to each of the inventions described in claim 1, 2, 3 or 4, and is most suitable as an application of the feeding mechanism of the present invention. The machine structure is specified on the Z-axis main shaft that reciprocally moves in the vertical direction of the machine tool, and it can achieve its purpose and effect.

  The invention described in claim 6 is the invention described with reference to each of the inventions described in claim 1, 2, 3, or 4, wherein the machining spindle is held horizontally and is vertically driven by a linear motor. It can be applied to a counter balancer device such as a slider that moves in a reciprocating axis and is effective.

  FIG. 1 and FIG. 2 are diagrams for explaining the operating state such as the air pressure inside the gas pressure balancer 15 same as that in FIG. 12 and FIG. 13 in the case of applying the present invention to the counter gas pressure balancer. In this case, the cylinder 15A of the balancer 15 is integrated with a quill 8 that reciprocally moves in the vertical Z-axis direction, and a piston 15B and a piston rod 15C are integrally fixed to a fixed portion such as a column by a connecting rod 16. Is when the quill is driven upward by a linear motor (not shown) and starts moving, and FIG. 2 is when the quill starts moving downward as opposed to FIG. In addition, the same thing which was demonstrated previously in FIG.12 and FIG.13 is attached | subjected and shown with the code | symbol which subtracted 100 from the code | symbol attached | subjected in FIG.12 and FIG.13, and description is abbreviate | omitted. .

  1 and 2, reference numerals 22 and 23 denote intake throttle valves called speed controllers (speed control valves) or the like in which variable throttle valves 22A and 23A and check valves 22B and 23B are connected in parallel. The intake throttle valve 22 connected to each sealed upper chamber 15RU and lower chamber 15RD divided by the piston 15B in the cylinder 15A via conduits 24 and 25 and further connected to the upper chamber 15RU is provided with the relief valve. The regulator 21 is connected to a required air pressure source via a valve 26 as necessary, while the other end 23C of the intake throttle valve 23 connected to the other lower chamber 15RD is opened to the outside as it is.

  In FIG. 1, the mechanical structure integrated with the quill 8 is configured such that the air pressure of the relief valve set pressure with respect to the upper chamber 15 RU of the gas pressure balancer 15 is mainly reduced by supplying the self-weight through the regulator 21 and the intake throttle valve 22 from the pressure air pressure source. In a state where the balance is stationary, the linear motor that drives the quill 8 has any movement command for positioning, or a minute lift servo control for maintaining a normal gap length and gap machining state during machining. When a feed command, or a jump operation command for raising the electrode based on the elapse of a predetermined set time or machining state detection is input, the linear motor responds and the quill 8 is driven and raised at an acceleration of 1.0 G or more. The inner volume of the upper chamber 15RU and the lower chamber 15RD of the balancer 15 tends to increase while the latter tends to decrease.

  However, according to the configuration of the air balancer 15 of FIG. 1 illustrated in FIG. 1, the supply of the pressure gas to the upper chamber 15RU via the regulator 21 is restricted with the check valve 22B for preventing the inflow. The inflow by the intake throttle valve 22 comprising the valve 22A is at least temporarily, that is, the inflow of the pressure gas from the throttle valve 22A cannot catch up to the speed at which the internal volume of the upper chamber 15RU increases or increases. In contrast to the phenomenon in which the restriction occurs, the lower chamber 15RD has a check valve 23B that is open and open while the internal volume is reduced. Therefore, there is no influence of the flow restriction by the throttle valve 23A, and the air in the lower chamber 15RD It is discharged almost without being compressed. That is, when doing so, when the quill 8 is lifted from the stationary state or when it is reversed and lifted from the lowered state, a phenomenon of adiabatic expansion occurs in the upper chamber 15RU of the cylinder 15, and the gas inside the work expands. The temperature is substantially commensurate with the amount, and cooling action is performed against heat generated by friction between the cylinder 15A and the piston 15B of the air balancer 15, and the cylinder 15A, piston 15B, piston rod 15C, quill 8 and the like due to the friction, etc. The temperature rise of the surrounding mechanical members will be prevented or suppressed.

  The upper chamber 15RU is described below with reference to FIG. 2 when the quill 8 is lifted by the linear motor drive, and when the quill 8 is lowered for any positioning or when the quill 8 is moved downward after reaching the rising vertex by jump. The internal volume is rapidly reduced to compress the internal pressure gas, but the pressure gas passes through the check valve 22B of the intake throttle valve 22 with almost no resistance and reaches the regulator 21, and the upper chamber 15RU. Since the pressure is released to the outside from the relief valve, which is set to substantially the same pressure, the pressure can be released to the outside only by generating a slight adiabatic compression state. However, at this time, even if the other lower chamber 15RD attempts to increase the internal volume rapidly and the cylinder 15A is moved downward and displaced downward, the inflow of outside air through the intake throttle valve 23 is caused by the check valve 23B. Due to the complete prevention and the inflow restriction by the throttle valve 23A, an adiabatic expansion action occurs in the lower chamber 15RD temporarily, if any, and the temperature of the internal gas decreases as described above, and the heat that raises the temperature around Therefore, the main cause of heat generation of the air balancer 15 is cooled from both the upper and lower sides, and the temperature rise is prevented or suppressed.

  FIG. 3 shows a temperature characteristic diagram measured by experimenting under the same conditions as the temperature characteristic diagram of FIG. 14 described above. According to the present invention, the jump speed JS: 36 m / min, acceleration : At about 1.5 G, the temperature rise is still greatly suppressed, and the temperature difference between the surrounding members is not significantly different. Therefore, the set movement trajectory and position accuracy of the mechanical structure can be maintained.

  When the intake throttle valves 22 and 23 act as an intake throttle so that the increase in the internal volume of the upper chamber 15RU or the lower chamber 15RD results in adiabatic expansion, the movement of the quill 8 is limited, but this is considered as an air spring. As a result, the energy required for the minute displacement amount at the beginning of movement by the high-response linear motor is less affected while the displacement amount is small, and is smaller than the force that moves a mechanical structure such as a quill with a linear motor at 1.0 G or more. Therefore, the operation of the drive by the linear motor is not substantially inhibited.

  As is clear from the description of FIGS. 1 and 2 and the like, the intake throttle valves 22 and 23 with respect to the upper chamber 15RU and the lower chamber 15RD of the counter balancer 15 do not always move up and down. In the case of a mechanical structure, it is obvious that it may be sufficient to provide an intake throttle valve in one of the intake conduits of the upper chamber 15RU or the lower chamber 15RD. Of course, in order to avoid unbalance of the load at the time of ascent and descent due to being provided on one side, and unbalance between the upper and lower sides of cooling, it is provided on both as in the above-described embodiment.

  INDUSTRIAL APPLICABILITY The present invention is useful when applied to a feed mechanism in which a counterbalance device for gas pressure is provided on a vertical axis moving body by a linear motor such as a machining spindle of a machine tool.

Operation | movement explanatory drawing of the principal part of this invention Example apparatus and a counter gas pressure balancer part. Operation | movement explanatory drawing of the counter gas pressure balancer part same as FIG. The measured temperature characteristic figure of the experiment example by a Die-sinker electric discharge machine. The perspective view which shows the whole structure of the die-sinking electric discharge machine equipped with the feed mechanism of the linear motor drive which has a gas pressure balancer of a prior art example. The cutting top view of the process spindle frame body part which follows the AA line of FIG. The cut | disconnection left side view of the process spindle frame body part which follows the BB line of FIG. The cutting | disconnection front view of the process spindle frame body part which follows the CC line of FIG. The figure which added the air supply source for air balancers to the cutting | disconnection left side view of FIG. The sectional side view for explanation of the modification in the conventional example of the processing spindle part of the feed mechanism of a linear motor drive. FIG. 10 is a side sectional view for explanation of a part of FIG. 9 changed. The perspective view which shows the whole structure of the machine tool for metal cutting carrying the linear motor drive feed mechanism which has a gas pressure balancer of a different conventional example. Operation | movement explanatory drawing of the gas pressure balancer part of a prior art example. The operation | movement explanatory drawing of a gas pressure balancer part similarly to FIG. The measured temperature characteristic figure of the experiment example in the apparatus of a prior art example.

Explanation of symbols

8 Quill 8B Hollow hole 15 Air balancer 15A Cylinder 15B Piston 15C Piston rod 15D Flange 15RU Upper chamber 15RD Lower chamber 16 Connecting rod 21 Regulator with relief valve 22, 23 Inlet throttle valve 22A, 23A Throttle valve 22B, 23B Check valve 24, 25 Conduit 26 On-off valve

Claims (6)

A feed mechanism for a mechanical structure that is held relative to a base body so as to be reciprocally movable in a vertical direction;
A gas pressure balancer in which a piston and a cylinder that support the mechanical structure with a gas pressure relative to the base move relatively reciprocally; and a linear motor that drives the mechanical structure with respect to the base to move the shaft. Prepared,
The gas pressure chamber of the gas pressure balancer into which the pressure gas that supports the weight of the mechanical structure is introduced includes the gas pressure source, the gas pressure regulator with a relief valve, and the inflow of the pressure gas from the gas pressure source through the regulator. A feed mechanism for a mechanical structure having a counter balance device, characterized in that the restricted exhaust is connected via an open intake throttle valve. A mechanical structure feeding mechanism provided to the base body so as to be reciprocally movable in the vertical direction,
An air balancer in which a piston and a cylinder that support the weight of the mechanical structure with respect to the base by air pressure are reciprocally moved; a linear motor that drives the mechanical structure relative to the base and moves the shaft; A position detection device that detects a linear movement position of the mechanical structure with respect to the base, and a drive control device that outputs a drive current to the linear motor while receiving feedback of a detection position signal from the position detection device in response to a position command from the control device And
The air chamber of the air balancer into which the air pressure that supports the weight of the mechanical structure is introduced is an air pressure source, an air regulator with a relief valve that is adjusted to the support air pressure, the inflow of pressure air is restricted, and the exhaust is open. A mechanical structure feed mechanism having a counter balance device, wherein the counter balance device is connected via an intake throttle valve.   The air chamber on the opposite side of the air balancer support air pressure chamber is sealed, and a conduit for inflowing and exhausting air is provided, and the exhaust is provided with an open intake throttle valve for restricting inflow of outside air to the conduit. A feed mechanism for a mechanical structure having the counterbalance device according to claim 1.   4. The feed mechanism for a mechanical structure having a counter balance device according to claim 1, wherein the intake throttle valve is a parallel connection body of a check valve and a throttle valve.   5. The feed mechanism for a machine structure having a counter balance device according to claim 1, wherein the machine structure is a Z-axis main shaft that reciprocally moves in a vertical direction of the machine tool. 5. The mechanical structure having a counter balance device according to claim 1, wherein the mechanical structure is a Z-axis slider that holds a horizontal main shaft of a machine tool and moves the reciprocating shaft in a vertical direction. Body feeding mechanism.

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