JP5385648B2 - Balancer device for linear drive machine tools - Google Patents

Description

  The present invention relates to a balancer device for a linear drive type machine tool, and in particular, is configured to prevent the spindle head from falling by braking the spindle head by a brake device provided in the balancer device including a gas spring when the power is shut off. About things.

  Conventionally, in a linear drive type machine tool, a spindle head is driven up and down while being guided by a column by driving a linear motor, and the spindle of the spindle head is driven by an electric motor to process a workpiece. In this type of machine tool, a heavy spindle head needs to be driven up and down by a linear motor, so the load on the linear motor increases and the responsiveness of the spindle head to rise and fall decreases. Therefore, in order to reduce the load on the linear motor and improve the response, the spindle head may be provided with a balancer device for canceling a part of the weight of the spindle head.

  By the way, the linear motor drives the spindle head up and down by magnetic force, so if the magnetic force is demagnetized when the power supply to the machine tool is cut off at the end of work or due to power failure or disconnection, the spindle head may fall. There is. Therefore, it is necessary to provide the spindle head with a brake device for preventing the spindle head from dropping when the power is turned off. As these brake devices, various devices as described in Patent Documents 1 to 3, for example, have been put into practical use.

  In the shaft feeding device of the electric discharge machining device described in Patent Document 1, an air cylinder is provided that causes a counter balance weight to act on the moving shaft of the mover (spindle head), and the piston rod of the air cylinder is compressed during a power failure. A brake mechanism that brakes by being clamped and fixed by a lever member by an urging force of a coil spring is provided. During normal operation, the piston rod is unlocked by pressurized air.

  In the air cushion cylinder device with a lock described in Patent Document 2, the cylinder device includes a lock ring that is loosely fitted on the piston rod and a spring that biases the lock ring in an inclined direction. In normal operation, the lock ring is placed in a posture perpendicular to the piston rod by the pressurized air, and the lock is released. At the time of power failure, the supply of pressurized air stops, and the lock ring is tilted by the biasing force of the spring to fix the piston rod. In the machine tool described in Patent Document 3, a lock mechanism similar to the lock mechanism of Patent Document 2 is applied to the lock mechanism that locks the piston rod.

Japanese Patent No. 3315945 JP 2003-336605 A JP 2007-98482 A

  However, in the brake mechanisms and lock mechanisms disclosed in Patent Documents 1 to 3, the piston rod is braked by sandwiching the surface of the piston rod with a lever member or a lock ring with the surface of the piston rod as a brake surface. Since the power supply of the machine tool is cut off at the end of every evening in the evening, there is a possibility that the surface of the piston rod may be gradually damaged by frequently turning off the power supply of the machine tool and putting it in a brake state.

  By the way, when a balancer device composed of a gas spring is adopted, the compressed nitrogen gas filled in the gas spring is, for example, 7 to 10 MPa, and the pressure is high. Therefore, the compressed nitrogen gas is also generated from a minute gap between the piston rod and the cylinder member. Leakage is likely to occur. Therefore, the surface of the piston rod of the gas spring is polished into a mirror surface. However, as described above, when a brake device that clamps the outer peripheral surface of the piston rod is provided, minute unevenness is generated on the outer peripheral surface of the piston rod, and gas tightness between the piston rod and the cylinder member is generated. This causes a problem that the compressed nitrogen gas of the gas spring is liable to leak to the outside, and the durability of the balancer device is significantly reduced.

  An object of the present invention is to provide a balancer device for a linear drive type machine tool provided with a brake device for preventing a spindle head from dropping by braking a cylinder member of a gas spring when the power is shut off.

  A balancer device for a linear drive machine tool according to a first aspect of the present invention provides a linear drive machine tool having a spindle head driven by a linear motor and a column for guiding the spindle head so as to be movable up and down. In a linear drive machine tool balancer device provided with a gas spring having a vertical cylinder member fixed to the spindle head so as to cancel a part of the spindle head, a brake device is provided to prevent the spindle head from dropping when the power is cut off. The brake device includes a case member fixed to the column and externally fitted to the cylinder member; a collet member supported by the case member and externally fitted to the cylinder member; and the case member, When shutting off, the collet member is compressed to a reduced diameter state to switch to a brake state that brakes the cylinder member, and power is not By opening the collet member in the expanded diameter state is characterized by comprising driving means for releasing the brake state during disconnection.

  A balancer device for a linear drive type machine tool according to a second aspect of the present invention is the balancer device according to the first aspect, wherein the collet member has a tapered outer peripheral surface whose diameter decreases toward the upper end side and at least one dividing slit extending in the vertical direction. Further, it is characterized in that it can be elastically deformed in a reduced diameter state.

  A balancer device for a linear drive type machine tool according to a third aspect of the present invention is the balancer device according to the second aspect, wherein the drive means is externally fitted to the collet member in the case member and is made smaller in diameter toward the upper end side, and A cylindrical member having a tapered inner circumferential surface forming a predetermined gap therebetween, a plurality of balls mounted in a tapered cylindrical gap between the tapered outer circumferential surface and the tapered inner circumferential surface, and the collet of the cylindrical member A plurality of compression springs that elastically urge downward relative to the member, and a fluid pressure cylinder capable of driving the cylindrical member upward relative to the collet member.

  The balancer device for a linear drive type machine tool according to a fourth aspect of the present invention is the balancer device according to the third aspect, wherein the fluid pressure cylinder includes a piston member formed of the cylindrical member and an annular shape that applies upward fluid pressure to the piston member. And a fluid working chamber.

  A balancer device for a linear drive type machine tool according to a fifth aspect of the present invention is the balancer device according to the fourth aspect, wherein an air passage for introducing pressurized air from a pressurized air supply source into the annular fluid working chamber of the fluid pressure cylinder, An electromagnetic direction switching valve is provided, which is provided and can discharge the fluid pressure in the annular fluid working chamber to the outside when the power is shut off.

A balancer device for a linear drive machine tool according to a sixth aspect of the present invention is the balancer device according to the third aspect , wherein an annular ball receiving member for receiving the plurality of balls from below is provided on the inner peripheral portion in the vicinity of the lower end of the cylindrical member. It is characterized by that.

  According to a seventh aspect of the present invention, the balancer device of the linear drive type machine tool is characterized in that a brake fluid pressure cylinder is provided instead of the plurality of compression springs.

  According to the first aspect of the present invention, a linear drive machine tool having a spindle head driven by a linear motor and a column for guiding the spindle head to be movable up and down cancels a part of its own weight. In the linear drive type machine tool balancer device with a gas spring having a vertical cylinder member fixed to the spindle head, a brake device is provided to prevent the spindle head from dropping when the power is shut down. The main spindle head can be prevented from dropping by the brake device when shut off.

  The brake device includes a case member fixed to the column and externally fitted to the cylinder member; a collet member supported by the case member and externally fitted to the cylinder member; The collet member is sometimes compressed to a reduced diameter state to switch to a brake state that brakes the cylinder member, and when the power is not shut off, the collet member is opened to an enlarged diameter state to release the brake state. The spindle head can be prevented from falling by compressing the collet member in a diameter-reduced state by the driving means during braking and braking the cylinder member.

  The brake state of the spindle head can be released by opening the collet member in an enlarged diameter state by the driving means when the power is not shut off. Since the case member and the collet member are externally fitted to the cylinder member and the outer peripheral surface of the cylinder member is sandwiched by the collet member during braking, the outer peripheral surface of the piston rod of the gas spring is not damaged. Therefore, the gas tightness between the cylinder member of the gas spring and the piston rod can be maintained, and the durability of the balancer device can be ensured.

  According to the invention of claim 2, the collet member has a tapered outer peripheral surface whose diameter is reduced toward the upper end side and at least one dividing slit extending in the vertical direction, and is configured to be elastically deformable in a reduced diameter state. Therefore, the collet member can be compressed to a reduced diameter state by the driving means.

  According to a third aspect of the present invention, the driving means is a taper inner peripheral surface that is externally fitted to the collet member in the case member and is reduced in diameter toward the upper end side to form a predetermined gap with the taper outer peripheral surface. A plurality of balls mounted in a tapered cylindrical gap between the tapered outer peripheral surface and the tapered inner peripheral surface, and elastically biasing the cylindrical member downward relative to the collet member A plurality of compression springs, and a fluid pressure cylinder capable of driving the tubular member relatively upward with respect to the collet member. The tapered inner peripheral surface of the shaped member engages with the tapered outer peripheral surface of the collet member via a plurality of balls, and the braking state can be maintained by compressing the collet member into a reduced diameter state. Accordingly, since the cylinder member is braked by the elastic force of the plurality of compression springs, the spindle head can be reliably braked and maintained in the brake state even during a power failure or disconnection.

  Since a plurality of balls are interposed between the taper outer peripheral surface of the collet member and the taper inner peripheral surface of the cylindrical member, a low friction state is achieved and the load from the cylindrical member can be efficiently transmitted to the collet member. it can. Since the fluid pressure can be supplied to the fluid pressure cylinder when the power is not shut off, the tubular member is driven upward by the fluid pressure cylinder to disengage the taper outer peripheral surface from the taper inner peripheral surface. The cylinder member can be maintained in the non-braking state by opening the shaft to the diameter-enlarged state.

  According to the invention of claim 4, the fluid pressure cylinder has a piston member made of the cylindrical member and an annular fluid working chamber for applying an upward fluid pressure to the piston member. Fluid pressure is supplied to the annular fluid working chamber, the piston member is driven upward by the fluid pressure, and the piston member made of a cylindrical member can be driven upward.

  According to the invention of claim 5, the air passage for introducing the pressurized air from the pressurized air supply source to the annular fluid working chamber of the fluid pressure cylinder, and the fluid in the annular fluid working chamber that is interposed in the air passage and shuts off the power. An electromagnetic direction switching valve that can release pressure to the outside is provided, so when the power is shut off, the electromagnetic direction switching valve is switched to a position where pressurized air in the annular fluid working chamber is released to the outside, and the annular fluid working chamber is opened to the atmosphere. Thus, the cylinder member can be surely brought into a braking state.

  According to the sixth aspect of the present invention, since the annular ball receiving member that receives the plurality of balls from below is provided on the inner peripheral portion in the vicinity of the lower end of the cylindrical member, the plurality of balls are annularly formed by the annular ball receiving member. The separation from the gap can be prevented.

  According to the seventh aspect of the present invention, since the brake fluid pressure cylinder is provided instead of the plurality of compression springs, the collet member is compressed into a reduced diameter state by the urging force of the brake fluid pressure cylinder when the power is shut off. By setting the brake state to brake the cylinder member, the spindle head can be prevented from dropping. A strong braking force can be generated by the brake fluid pressure cylinder.

1 is a side view of a linear drive type machine tool provided with a balancer device (a gas spring is in a maximum extension state) according to Embodiment 1 of the present invention. It is a side view of a linear drive type machine tool (a gas spring is in a maximum retracted state). It is a top view of a linear drive type machine tool. It is a side view of a gas spring and a brake device. It is a top view of a brake device. FIG. 6 is a sectional view taken along line VI-VI in FIG. 5. It is the VII-VII sectional view taken on the line of FIG. It is sectional drawing of the brake device which concerns on Example 2. FIG.

  Hereinafter, modes for carrying out the present invention will be described based on examples.

First, the overall configuration of a vertical linear drive machine tool 1 provided with the balancer device 5 of the present invention will be described.
As shown in FIGS. 1 to 3, a linear drive type machine tool 1 (hereinafter referred to as a machine tool 1) drives a spindle head 2, a column 3 that guides the spindle head 2 so as to be movable up and down, and the spindle head 2. A linear motor 4 is provided. In the machine tool 1, a balancer device 5 that cancels a part of the weight of the spindle head 2 and reduces the load on the linear motor 4 is provided on the spindle head 2. In the following description, the top and bottom of FIG.

  The spindle head 2 is supported by a frame member 6, a front part of the frame member 6 so as to be rotatable about a vertical axis, a spindle 8 for detachably mounting a tool on a lower end part, and an electric motor for driving the spindle 8 to rotate. It has a motor 9 and the like. The electric motor 9 is attached to the upper end portion of the front portion of the frame member 6 and connected to the main shaft 8. The electric motor 9 is electrically connected to the control unit 11 and is driven and controlled by the control unit 11 so that the tool is rotated together with the main shaft 8.

  A pair of left and right guide rails 12 extending vertically are provided at the front end of the column 3, and two pairs of left and right slides 13 are fixed to the rear end of the frame member 6 of the spindle head 2. Two pairs of slides 13 are engaged, and the spindle head 2 is guided to be raised and lowered.

  As shown in FIG. 3, the linear motor 4 includes a pair of left and right coil yokes 15, a pair of left and right magnet plates 16, and the like. The pair of coil yokes 15 are provided at the front end portion of the column 3 so as to face each other with the spindle head 2 sandwiched from both the left and right sides, and each coil yoke 15 has a plurality of coils arranged at predetermined intervals in the vertical direction. . On the other hand, the pair of magnet plates 16 are provided on both the left and right side surfaces of the spindle head 2 and have a plurality of permanent magnet pieces arranged at set intervals in the vertical direction. By controlling the current supplied to the plurality of coils of the pair of coil yokes 15, the spindle head 2 is driven up and down by the magnetic force generated between the permanent magnets and the coils.

Next, the balancer device 5 will be described.
As shown in FIGS. 1-8, the balancer apparatus 5 is comprised from the gas spring 20, the brake device 25, etc. FIG. The balancer device 5 is configured to urge the spindle head 2 upward by the gas spring 20 and reduce the load of the linear motor 4 by the urging force of the compressed nitrogen gas filled in the gas spring 20.

  The gas spring 20 is arranged in a vertical posture inside the spindle head 2 so as to cancel a part of its own weight. The gas spring 20 includes a cylinder member 21, a piston rod 22, a gas working chamber (not shown), a compressed nitrogen gas filled in the gas working chamber, and the cylinder member 21 is a lower end of the cylinder member 21. It is fixed to the spindle head 2 via a bracket 24 fixed to the part. A piston rod 22 extends downward from the cylinder member 21, and a lower end of the piston rod 22 is in contact with a lower portion of the column 3. The gas working chamber in the cylinder member 21 is filled with compressed nitrogen gas (for example, a gas pressure of 7 to 10 MPa), and the piston rod 24 is strongly biased downward.

Next, the brake device 25 will be described.
As shown in FIGS. 4 to 8, the brake device 25 is externally fitted to the cylinder member 21 of the gas spring 20. The brake device 25 includes a case member 26, a collet member 27 supported by the case member 26 and externally fitted to the cylinder member 21, drive means 29 provided on the case member 26, and the like. The brake device 25 is configured to prevent the spindle head 2 from dropping by setting the brake state in which the cylinder member 21 of the gas spring 20 is braked when the power is shut off.

Next, the case member 26 will be described.
As shown in FIGS. 6 and 7, the case member 26 includes a metal cylindrical main body portion 31 and a metal annular plate portion 32. The case member 26 is externally fitted into the cylinder member 21 with a slight gap. The case member 26 is fixed to a connecting portion 28 provided in a protruding shape at the front portion of the column 3 by eight bolts 28 a, and the case member 26 is supported by the column 3 through the connecting portion 28.

  On the inner peripheral portion of the cylindrical main body portion 31, an annular plate portion mounting portion 33 to which the annular plate portion 32 is mounted, a large diameter hole portion 34, and a small diameter smaller than the large diameter hole portion 34 from the top to the bottom A hole 35 and a cylinder insertion hole 36 through which the cylinder member 21 is inserted with a slight gap are sequentially formed. A flange portion 37 is formed on the outer peripheral portion near the upper end of the cylindrical main body portion 31, and eight bolt holes 31 a are formed in the flange portion 37 at equal intervals in the circumferential direction.

The annular plate part 32 has a cylinder insertion hole 38 formed in the center part for allowing the cylinder member 21 to pass therethrough, and eight bolt holes 32a formed in the outer peripheral part at equal intervals in the circumferential direction. The annular plate portion 32 is attached to the annular plate portion attachment portion 33 so that the eight bolt holes 32a and the eight bolt holes 31a of the cylindrical main body portion 31 coincide with each other, and the eight bolts 28a are attached to the connecting portion 28. It is fixed. The annular plate portion 32 is formed with two bolt insertion holes 32b through which two bolts (not shown) are inserted so as to face each other across the axis of the cylinder member 21. The two bolt insertion holes 32b are used for fixing the driving means 29 described later.
A pair of dust and dust attached to the cylinder member 21 is prevented from entering the inside of the case member 26 from the outside in the insertion hole 36 of the cylindrical main body 31 and the insertion hole 38 of the annular plate portion 32. Dust seals 39a and 39b are provided.

Next, the collet member 27 will be described.
As shown in FIG. 6 and FIG. 7, the collet member 27 is made of a metal formed in an annular shape, and has a tapered outer peripheral surface 41 that decreases in diameter toward the upper end side, and one dividing slit 42 that extends in the vertical direction. The cylinder member 21 has a cylinder insertion hole 43 through which the cylinder member 21 is inserted, and is configured to be elastically deformable in a reduced diameter state in close contact with the outer peripheral surface of the cylinder member 21. The collet member 27 is supported by the case member 26 and is externally fitted to the cylinder member 21 with a slight gap.

  The lower end of the collet member 27 is in contact with the annular bottom surface 40 of the case member 26, and a slight gap is formed between the upper end of the collet member 27 and the lower end surface of the annular plate portion 32. At the upper end of the tapered outer peripheral surface 41 of the collet member 27, an annular restricting portion 44 that restricts the later-described plurality of balls 46 from separating upward is formed. Note that the number of the dividing slits 42 is not necessarily one, and a plurality of dividing slits 42 may be formed.

Next, the drive means 29 will be described.
As shown in FIGS. 6 and 7, the drive means 29 includes a metal cylindrical member 45, a plurality of balls 46, a plurality of compression springs 47, a fluid pressure cylinder 48, and the like. The drive means 29 is mounted on the case member 26 and compresses the collet member 27 to a reduced diameter state when the power is cut off to switch the brake state to brake the cylinder member 21 and opens the collet member 27 to the enlarged diameter state when the power is not cut off. The brake state is then released.

  The cylindrical member 45 is integrally formed of a main body cylindrical portion 51 and a small diameter cylindrical portion 52, the main body cylindrical portion 51 is slidably inserted into the large diameter hole portion 34, and the small diameter cylindrical portion 52 is small diameter hole portion 35. It is slidably inserted in. The cylindrical member 45 is externally fitted to the collet member 27 in the case member 26 and has a tapered inner peripheral surface that is reduced in diameter toward the upper end side and forms a gap equal to the diameter of a ball 46 to be described later. 53. Two bolt holes 51 a are formed in the upper end portion of the main body cylinder portion 51 so as to face each other with the axis of the cylinder member 21 interposed therebetween.

  The plurality of balls 46 (steel balls) are mounted in a state in which the tapered cylindrical gap 54 between the tapered outer peripheral surface 41 and the tapered inner peripheral surface 53 is densely filled. An annular ball receiving member 55 that receives the plurality of balls 46 from below is provided on the inner peripheral portion in the vicinity of the lower end of the cylindrical member 45. Note that an engagement preventing member that prevents the ball 46 from engaging with the slit 42 may be provided in one dividing slit 42.

  The plurality of compression springs 47 are mounted in compression on a plurality of spring mounting portions 57 formed at equal intervals in the circumferential direction across the tubular member 45 and the annular plate portion 32. The plurality of compression springs 47 elastically bias the cylindrical member 45 downward relative to the collet member 27. In a state where pressurized air is not supplied to the fluid pressure cylinder 48, the cylindrical member 45 is elastically biased downward by the plurality of compression springs 47, and the tapered inner peripheral surface 53 is connected to the tapered outer peripheral surface via the plurality of balls 46. The collet member 27 is elastically deformed to a reduced diameter state. In a state where pressurized air is supplied to the fluid pressure cylinder 48, as shown in FIGS. 6 and 7, the tubular member 45 is driven upward to engage the tapered outer peripheral surface 41 and the tapered inner peripheral surface 53. Is released, and the collet member 27 is opened in an enlarged state. In the present invention, six or eight sets of the plurality of compression springs 47 and the plurality of spring mounting portions 57 are provided.

Next, the fluid pressure cylinder 48 will be described.
As shown in FIGS. 6 and 7, the fluid pressure cylinder 48 includes a piston member made up of a cylindrical member 45, a cylinder hole made up of the large-diameter hole portion 34 of the case member 26, and an upwardly applied to the piston member 45. And an annular fluid working chamber 58 on which pressurized air (corresponding to fluid pressure) acts. The fluid pressure cylinder 48 is configured to be able to drive the piston member 45 (cylindrical member 45) relatively upward with respect to the collet member 27 when releasing the brake state.

  The annular fluid working chamber 58 is composed of an annular space defined by the case member 26 and the piston member 45. The annular fluid working chamber 58 is supplied with pressurized air from a pressurized air supply source 60 via an air supply path 59 formed in the case member 26. When pressurized air is supplied to the annular fluid working chamber 58, the piston member 45 is driven upward against the urging force of the plurality of compression springs 47, and the brake is released. The piston member 45 and the cylinder hole 34 are fitted with a pair of annular seal members 59a and 59b for keeping the inside of the annular fluid working chamber 58 airtight.

  As shown in FIG. 6, the balancer device 5 is provided with an air passage 61 for introducing pressurized air from a pressurized air supply source 60 into the annular fluid working chamber 58 of the fluid pressure cylinder 48, and the air passage 61. An electromagnetic direction switching valve 62 is provided that can release pressurized air in the annular fluid working chamber 58 to the outside when the power is shut off. The upstream side of the air passage 61 is connected to a pressurized air supply source 60, and the downstream side is connected to an air supply path 59 of the brake device 25. The electromagnetic direction switching valve 62 is switched by turning on / off the solenoid 63 by the control unit 11.

  The state shown in FIG. 6 shows a state where the solenoid 63 of the electromagnetic direction switching valve 62 is turned on and switched to the supply position. Pressurized air is supplied from the pressurized air supply source 60 to the annular fluid working chamber 58 via the air passage 61 and the air supply path 59, and the brake is in a non-braking state. When the power is shut off, the solenoid 63 of the electromagnetic direction switching valve 62 is turned off to switch to the discharge position, so that the annular fluid working chamber 58 is opened to the atmosphere and the braking state is set. The electromagnetic direction switching valve 62 is also provided with a silencer 64 for attenuating sound during exhaust.

  When the brake device 25 is assembled to the gas spring 20 or maintenance is performed, two bolts are inserted into the bolt insertion holes 32b of the annular plate portion 32 and screwed into the bolt holes 51a of the cylindrical member 45, respectively. Thus, the cylindrical member 45 is pulled and fixed to the annular plate portion 32 of the case member 26 against the urging force of the plurality of compression springs 47, and the tapered outer peripheral surface 41 is engaged with the tapered inner peripheral surface 53. It is cancelled | released and the collet member 27 can be maintained in a diameter expansion state.

Next, the operation and effect of the balancer device 5 of the machine tool 1 of the present invention will be described.
First, since the control unit 11 is stopped before the power of the machine tool 1 is turned on, the electromagnetic direction switching valve 62 maintains the discharge position, and the annular fluid working chamber 58 of the brake device 5 is opened to the atmosphere. The cylindrical member 45 is elastically biased downward by the urging forces of the plurality of compression springs 47, the tapered outer peripheral surface 41 engages with the tapered inner peripheral surface 53 via the plurality of balls 46, and the collet member 27 has a diameter. Compressed to a reduced state. The collet member 27 brakes the cylinder member 21 of the gas spring 20 so that the spindle head 2 is fixed to the column 3.

  When the machine tool 1 is powered on, the control unit 11 switches the electromagnetic direction switching valve 62 to the supply position shown in FIG. 6 to supply pressurized air from the pressurized air supply source 60 to the annular fluid working chamber 58. . Pressurized air drives the cylindrical member 45 (piston member) upward against the urging force of the plurality of compression springs 47, disengages the tapered outer peripheral surface 41 from the tapered inner peripheral surface 53, By opening the collet member 27 in the diameter enlarged state, the brake state in which the brake device 25 brakes the cylinder member 21 is released. Thereafter, the machine tool 1 is subjected to various processes while canceling a part of its own weight of the spindle head 2 by elastic biasing of the balancer device 5 to the upper side of the gas spring 20.

  Here, when the power supply to the machine tool 1 is interrupted due to the interruption of the power supply of the machine tool or the power failure or the disconnection at the end of work, when the energization from the control unit 11 to the solenoid 63 is stopped, the electromagnetic direction switching valve 62. Is switched to the discharge position, and the pressurized air in the annular fluid working chamber 58 is discharged to the outside, and the atmosphere is released. In this state, the cylindrical member 45 is elastically biased downward by the plurality of compression springs 47, the tapered outer peripheral surface 41 is engaged with the tapered inner peripheral surface 53 via the plurality of balls 46, and the collet member 27 is moved. The main shaft head 2 is prevented from falling by being compressed to a reduced diameter state to be in a braking state in which the cylinder member 21 is braked.

  In this way, the spindle head 2 is canceled by the machine tool 1 having the spindle head 2 driven by the linear motor 4 and the column 3 for guiding the spindle head 2 so as to be movable up and down so as to cancel a part of its own weight. In the balancer device 5 of the machine tool 1 provided with the gas spring 20 having the cylinder member 21 in a vertical posture fixed to the brake device 25 for preventing the spindle head 2 from dropping when the power is shut off, the machine tool 1 is provided. The spindle head 2 can be prevented from dropping via the balancer device 5 by the brake device 25 when the power is turned off.

  The brake device 25 includes a case member 26 fixed to the column 3 and externally fitted to the cylinder member 21, a collet member 27 supported by the case member 26 and externally fitted to the cylinder member 21, and the case member 26. Equipped with a drive means for compressing the collet member 27 to a reduced diameter state when the power is shut off to switch to a brake state for braking the cylinder member 21 and opening the collet member 27 to a larger diameter state for releasing the brake state when the power is not shut off. 29, the collet member 27 is compressed to a reduced diameter state by the driving means 29 when the power is shut off, and the cylinder member 21 is braked to prevent the spindle head 2 from falling. .

  When the power supply is not shut off, the collet member 27 can be opened in the diameter-enlarged state by the driving means 29 to release the brake state of the spindle head 2. Since the case member 26 and the collet member 27 are externally fitted to the cylinder member 21 and the outer peripheral surface of the cylinder member 21 is sandwiched by the collet member 27 during braking, the outer peripheral surface of the cylinder member 21 may be damaged. However, the outer peripheral surface of the piston rod 24 of the gas spring 20 is not damaged. Therefore, the gas tightness of the spring 20 can be maintained and the durability of the balancer device 5 can be ensured.

  The collet member 27 has a tapered outer peripheral surface 41 having a smaller diameter toward the upper end side and at least one dividing slit 42 extending in the vertical direction. The collet member 27 is configured to be elastically deformable in a reduced diameter state. The member 27 can be compressed to a reduced diameter state.

  The driving means 29 is fitted to the collet member 27 in the case member 26 and has a tapered inner peripheral surface 53 having a tapered inner peripheral surface 53 that is reduced in diameter toward the upper end side to form a predetermined gap with the tapered outer peripheral surface 41. , A plurality of balls 46 mounted in a tapered cylindrical gap 54 between the tapered outer peripheral surface 41 and the tapered inner peripheral surface 53, and a plurality of elastically urging the cylindrical member 45 downward relative to the collet member 27. The compression spring 47 and the fluid pressure cylinder 48 capable of driving the cylindrical member 45 upward relative to the collet member 27 have the following effects.

  The cylindrical member 45 is elastically biased downward by the plurality of compression springs 47, and the tapered inner peripheral surface 53 of the cylindrical member 45 is engaged with the tapered outer peripheral surface 41 of the collet member 27 via the plurality of balls 46. The braking state can be maintained by compressing the member 27 in a reduced diameter state. Therefore, since the cylinder member 21 is braked by the elastic force of the plurality of compression springs 47, the spindle head 2 can be reliably braked and maintained in the brake state even at the time of power failure or disconnection. Since a plurality of balls are interposed between the taper outer peripheral surface of the collet member and the taper inner peripheral surface of the cylindrical member, a low friction state is achieved and the load from the cylindrical member can be efficiently transmitted to the collet member. it can. Since pressurized air can be supplied to the fluid pressure cylinder 48 when the power is not shut off, the tubular member 45 is driven upward by the fluid pressure cylinder 48 and the engagement between the tapered outer peripheral surface 41 and the tapered inner peripheral surface 53 is released. Thus, the collet member 27 can be maintained in the non-braking state by opening the collet member 27 in the diameter enlarged state.

  The fluid pressure cylinder 48 includes a piston member 45 formed of a cylindrical member 45 and an annular fluid working chamber 58 that applies upward fluid pressure to the piston member 45, so that fluid pressure is supplied to the annular fluid working chamber 58. Then, the piston member 45 can be driven upward with pressurized air, and the piston member formed of the cylindrical member 45 can be driven upward.

  An air passage 61 that introduces pressurized air from a pressurized air supply source 60 to the annular fluid working chamber 58 of the fluid pressure cylinder 48, and the pressurized air in the annular fluid working chamber 58 that is interposed in the air passage 61 when the power is shut off. Since the electromagnetic direction switching valve 62 that can be discharged to the outside is provided, the pressurized air in the annular fluid working chamber 58 is switched by the electromagnetic direction switching valve 62 so that it can be discharged to the outside when the power is shut off. The cylinder member 21 can be surely brought into a braking state by opening to the atmosphere.

  Since the annular ball receiving member 55 for receiving the plurality of balls 46 from below is provided on the inner peripheral portion in the vicinity of the lower end of the cylindrical member 45, the plurality of balls 46 are separated from the annular gap by the annular ball receiving member 55. Can be prevented.

  Next, a brake device 25A according to Example 2 in which the brake device 25 of Example 1 is partially changed will be described with reference to FIG. However, the same constituent elements as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and only different constituent elements are described. In the drive unit 29A of the brake device 25A, a plurality of hydraulic cylinders 70 (corresponding to brake fluid pressure cylinders) are provided instead of the plurality of compression springs 47.

  As shown in FIG. 8, the plurality of hydraulic cylinders 70 are respectively mounted on a plurality of cylinder mounting portions 71 formed over the cylindrical member 45 and the annular plate portion 32. The hydraulic cylinder 70 includes a cylinder member 72, a piston member 73, a hydraulic operation chamber 74, and the like. The piston member 73 is mounted in a cylinder hole of the cylinder member 72 so as to be oil-tightly slidable. The leading end surface of the piston member 73 is on the bottom surface of the cylinder mounting portion 71 (the bottom surface formed on the cylindrical member 45). It is in contact. The plurality of hydraulic working chambers 74 are connected to a hydraulic accumulator 77 through a hydraulic supply / exhaust port 75, and hydraulic pressure is supplied from the hydraulic accumulator 77. The acting force (pressing force) on the tubular member 45 by the plurality of piston members 73 is smaller than the acting force by the pressurized air supplied to the annular fluid working chamber 58.

  When the power is not shut off, the cylindrical member 45 is driven upward by pressurized air, and the balancer device 5 is brought into a non-braking state. At this time, a part of the hydraulic pressure in the plurality of hydraulic working chambers 74 is accumulated in the hydraulic accumulator 77. When the power is shut off, the supply of pressurized air is stopped as in the first embodiment, and the inside of the annular fluid working chamber 58 is opened to the atmosphere, so that the hydraulic pressure of the hydraulic accumulator 77 is supplied to the hydraulic working chamber 74 and the cylindrical member 45 is driven downward to enter a braking state.

  Since the hydraulic cylinder 70 (braking fluid pressure cylinder) is provided instead of the plurality of compression springs 47, the collet member 27 is compressed to a reduced diameter state by the urging force of the hydraulic cylinder 70 when the power is shut off, and the cylinder member 21 is By setting the brake state to be braked, the spindle head 2 can be prevented from dropping. The hydraulic cylinder 70 can generate a strong braking force. Other configurations, operations, and effects are the same as those of the first embodiment, and thus description thereof is omitted.

Next, a modified example in which the first and second embodiments are partially modified will be described.
[1] The configuration of the electromagnetic direction switching valve 62 of the first and second embodiments is merely an example, and pressurized air is supplied from the pressurized air supply source 60 to the annular fluid working chamber 58 when the power is not shut off. Any configuration can be used as long as the pressurized air in the annular fluid working chamber 58 is discharged, and electromagnetic directional control valves having various configurations can be applied.

[2] Instead of the pressurized air supply source 60 and the air passage 61 of the first and second embodiments, a hydraulic pressure supply source and an oil passage may be provided. When releasing the brake state, hydraulic pressure is supplied into the annular fluid working chamber to drive the piston member 45 upward. The hydraulic pressure in the annular fluid working chamber in the brake state is discharged to the hydraulic tank through the oil passage.

[3] The arrangement of the linear motor 4 and the balancer device 5 with respect to the spindle head 2 of the first and second embodiments is merely an example. For example, the linear motor 4 has a configuration in which the balancer device 5 is provided on one or both side surfaces of the spindle head 2, the magnet plate 16 is mounted on the rear end surface of the spindle head 2, and the coil yoke 15 is provided on the front end surface of the column 3. Also good.
[4] In addition, those skilled in the art can implement the present invention by adding various modifications without departing from the spirit of the present invention, and the present invention includes such modifications. is there.

  The balancer device of the linear drive machine tool of the present invention can be provided in various linear drive machine tools. It can also be used for machine tools other than linear drive machine tools.

DESCRIPTION OF SYMBOLS 1 Linear drive type machine tool 2 Spindle head 3 Column 4 Linear motor 5 Balancer device 20 Gas spring 21 Cylinder member 25, 25A Brake device 26 Case member 27 Collet member 29, 29A Drive means 32 Annular plate part 41 Taper outer peripheral surface 42 Dividing slit 45 Cylindrical member 45 Piston member 46 Ball 47 Compression spring 48 Fluid pressure cylinder 53 Tapered inner peripheral surface 54 Tapered cylindrical gap 55 Annular ball receiving member 58 Annular fluid working chamber 60 Pressurized air supply source 61 Air passage 62 Electromagnetic direction switching valve 70 Hydraulic cylinder

Claims (7)

A linear drive machine tool having a spindle head driven by a linear motor and a column that guides the spindle head to be able to move up and down has a vertical posture fixed to the spindle head so as to cancel a part of its own weight. In a linear drive machine tool balancer device provided with a gas spring having a cylinder member,
A brake device is provided to prevent the spindle head from dropping when the power is turned off.
The brake device is
A case member fixed to the column and externally fitted to the cylinder member;
A collet member supported by the case member and externally fitted to the cylinder member;
The case member is equipped with a collet member that is compressed to a reduced diameter state when the power is shut off and switched to a brake state that brakes the cylinder member. A balancer device for a linear drive type machine tool, characterized by comprising a drive means.   2. The collet member according to claim 1, wherein the collet member has a tapered outer peripheral surface whose diameter decreases toward the upper end side, and at least one dividing slit extending in a vertical direction, and is configured to be elastically deformable in a reduced diameter state. The linear drive machine tool balancer device described. The driving means includes
A cylindrical member that has a tapered inner peripheral surface that is externally fitted to the collet member in the case member and has a smaller diameter toward the upper end side to form a predetermined gap with the tapered outer peripheral surface;
A plurality of balls mounted in a tapered cylindrical gap between the tapered outer peripheral surface and the tapered inner peripheral surface;
A plurality of compression springs that elastically urge the tubular member downward relative to the collet member;
The balancer device for a linear drive type machine tool according to claim 2, further comprising a fluid pressure cylinder capable of driving the cylindrical member upward relative to the collet member.   4. The linear drive type machine tool according to claim 3, wherein the fluid pressure cylinder has a piston member made of the cylindrical member and an annular fluid working chamber for applying an upward fluid pressure to the piston member. Mechanical balancer device.   An air passage that introduces pressurized air from a pressurized air supply source into the annular fluid working chamber of the fluid pressure cylinder, and an electromagnetic direction that is interposed in the air passage and can release the fluid pressure in the annular fluid working chamber to the outside when the power is shut off The balancer device for a linear drive machine tool according to claim 4, further comprising a switching valve. The balancer device for a linear drive machine tool according to claim 3 , wherein an annular ball receiving member that receives the plurality of balls from below is provided on an inner peripheral portion in a vicinity of a lower end of the cylindrical member.   4. The linear drive machine tool balancer device according to claim 3, wherein a brake fluid pressure cylinder is provided in place of the plurality of compression springs.