JP2005069387A - Rod-less cylinder for balancer of machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rod-less cylinder for a balancer of a machine tool shortened in the longitudinal dimension in comparison with an air cylinder with a rod and smoothly working with elevation of a spindle head. <P>SOLUTION: A piston 26 of the rod-less cylinder 25 as a balance cylinder for energizing the spindle head 6 upward is connected to the spindle head 6 provided in a column freely to be elevated by an elevation driving means 12. The piston 26 is provided with a piston packing 45 in the only one end thereof on a pressurizing cylinder chamber 42 side wherein a pressure-air control device 28 is connected and the fluid pressure for energizing the spindle head 6 works. Lubricant holding rings 48 and 48 are provided in front and rear of the packing 45 in the axial direction to prevent using-up of an oil film during operation, and the piston 26 is smoothly operated not to hinder elevation of the spindle head 6. A discharge side cylinder chamber 43 of the rod-less cylinder 25 is opened to the atmospheric pressure through a first port 57. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a balance device for a machine tool that applies an upward biasing force to a spindle head by a balance cylinder in order to balance the weight of the spindle head guided so as to be movable up and down to a column.

  Conventionally, in order to reduce the load applied to the lifting drive means for driving the spindle head guided and supported by the column of the machine tool so as to be lifted and lowered, the spindle head is provided with a balance device for reducing the weight of the spindle head. ing. The balance device includes a balance cylinder, and adjusts the application of an upward biasing force to the spindle head by supplying and discharging pressurized fluid to and from the balance cylinder. As such a balance device, the device of Patent Document 1 is known. In this device, an air cylinder having a piston rod is used as a balance cylinder. A uniform force is applied between the piston of the air cylinder and the cylinder tube, and between the piston rod and the cylinder body by the pressure-adjustable fluid in the annular groove on the seal member covering the annular groove provided on the piston and cylinder body. And sealing with the seal member eliminates the bite of the seal member and reduces the sliding resistance. Patent Document 2 discloses a balance device using an air cylinder. In the thing of patent document 3, the cylinder rod is penetrated by the cylinder with which gas was enclosed, and the balance rod is comprised by attaching a cylinder rod to a vertical axis | shaft unit so that integral movement is possible. A seal member is provided between the cylinder rod and the through hole of the cylinder through which the cylinder rod passes.

  Patent Documents 4 and 5 do not show a balance cylinder of a balance device, but disclose a structure of a rodless cylinder. In the thing of patent document 4, piston packing is fitted in the outer periphery of the piston which comprises the inner side moving body of a rodless cylinder, and the grease reservoir part is provided in the axial direction both sides which pinched the piston packing. It is described that a felt ring as an oil supply member (lubricant holding ring) that can contain grease is provided as the grease reservoir portion. In Patent Document 5, a lubricant retaining ring is mounted on the inner side in the axial direction of the piston packing that is mounted on both ends of the piston in the axial direction, and lubrication from the lip sliding contact surface by the lip of the piston packing is lubricated from the lubricant retaining ring. It is repaired by supplying the agent.

  Patent Documents 6 to 8 disclose a pneumatic piping device using a rodless cylinder, and a pressurized fluid is supplied to the outside from a cylinder chamber via a piston. In Patent Document 6, the piston is provided with a passage that connects the cylinder chambers on both sides to the outside of the cylinder across the piston, and the passage is provided with a shuttle valve. When pressure is applied to one cylinder chamber of the cylinder by the pressurized fluid, the shuttle valve closes the communication between the other cylinder chamber and the passage so that the pressurized fluid in one cylinder chamber can be supplied from the piston to the outside. In Patent Documents 7 and 8, a passage is provided in the piston unit, and compressed air supplied to the cylinder chamber can be supplied from the passage of the piston unit to a pneumatic device outside the piston unit.

  In patent documents 1-3, since the air cylinder provided with the cylinder rod was used as a balance cylinder, there existed a problem that a longitudinal dimension became long. Patent Documents 1 to 8 do not describe using a rodless cylinder as a balance cylinder. Further, since Patent Document 4 is a magnet type rodless cylinder, it is not practical for supporting the spindle head.

Further, in a standard rodless cylinder, piston packing is attached to both ends of the piston, and the pressing force of the piston packing is increased in order to improve the sealing performance between the cylinder tube inner surface. Further, since the structure for holding the lubricant as shown in Patent Documents 4 and 5 is not provided, the lubricating oil film on the inner surface of the cylinder tube is cut by the piston packing, and the oil film is cut halfway. For this reason, when the oil film is cut halfway, the sliding resistance of the piston packing increases, and the movement of the piston becomes a staggered movement, which may not move smoothly. In a machine tool using a linear motor as a driving device, the spindle head is moved up and down at high speed. However, because the force of the linear motor is weak, the piston that does not move smoothly when the standard rodless cylinder is used as a balance cylinder. This prevents the spindle head from moving up and down smoothly. In addition, since the spindle head repeats raising and lowering at random, the piston also rises and stops at random following the spindle head, causing oil shortage at the place where it is randomly stopped and preventing smooth operation.
JP-A-11-77471 Japanese Patent No. 30009509 JP 2000-153418 A JP-A-9-112504 JP 2002-274171 A JP 51-28793 A JP-A-8-128402 Japanese Patent Laid-Open No. 61-286603

  The present invention provides a rodless cylinder for a balance device of a machine tool that has a shorter longitudinal dimension and a longer stroke than an air cylinder with a rod and that operates smoothly following the raising and lowering of a spindle head.

  The present invention is a rodless cylinder used as the balance cylinder in a balance device of a machine tool provided with a balance cylinder that guides the spindle head up and down to a column by an elevation drive means and urges the spindle head upward. In the rodless cylinder, an external moving body outside the cylinder tube connected to the piston fitted in the cylinder chamber of the cylinder tube so as to be movable in the axial direction is connected to the spindle head, and the spindle head is moved upward to the piston. A piston packing is provided only at the end of the pressurizing side cylinder chamber on which the energizing fluid pressure acts, and a lubricant holding ring having a lubricant holding function is provided before and after the piston packing in the axial direction.

  The pressure-side cylinder chamber of the rodless cylinder and the discharge-side cylinder chamber on the opposite side across the piston are at atmospheric pressure by a first port provided in the end cap and a second port provided in the external moving body via the piston. Released.

  In addition, the piston has a standard configuration having a packing mounting groove for mounting a piston packing at both ends in the cylinder axial direction, and the front and rear of the packing mounting groove on the pressure side cylinder chamber side of the piston in the cylinder axial direction. The ring mounting groove for mounting the lubricant retaining ring is additionally mounted, or a ring mounting plate with a ring mounting groove is additionally mounted, a piston packing is mounted in the packing mounting groove, and the ring mounting grooves before and after the piston packing are mounted. Install the lubricant retaining ring.

  In the device of the present invention, the balance cylinder is a rodless cylinder, so that the stroke can be lengthened and the longitudinal dimension can be shortened as compared with an air cylinder having a cylinder rod. Also, a piston packing is attached only to the end of the pressurized cylinder chamber side where the piston's pressurized fluid acts, and a lubricant retaining ring is provided around the cylinder axial direction of the piston packing, so the piston slides in the cylinder chamber. The sliding resistance due to the piston packing is reduced to one place, so that the oil film is cut off halfway by the lubricant retaining ring. Thereby, even when there is no force at high speed as in the case of linear motor driving, the spindle head can be smoothly raised and lowered randomly. And if the discharge side cylinder chamber of the rodless cylinder is released to atmospheric pressure by the first port provided in the end cap and the second port provided in the external moving body integrated with the piston, the air in the discharge side cylinder chamber is at two locations. Therefore, when the stroke is long or when the piston moves at a high speed following the high speed movement of the spindle head, the air can be discharged quickly and a large amount of air can be prevented from being compressed. Thus, the pressure rise is suppressed, and this also does not hinder the smooth movement of the spindle head. In addition, if a ring mounting groove is added to the packing mounting groove on one side of a standard rodless cylinder piston that does not have a lubricant holding ring, and an additional lubricant holding ring is used, A rodless cylinder can be used and it becomes inexpensive.

  Embodiments of the present invention will be described with reference to FIGS. On the base 2 of the machine tool 1, a column 3 is movably guided by a guide rail 4 in the left-right direction. A stator (fixed magnet) 5a of the linear motor 5 is attached to the upper surface of the base 2, and a mover (coil) 5b is attached to the lower surface of the column 3 facing the stator 5a. The movable element 5b constitutes a linear motor 5 for moving the column 3 to the left and right. The moving column 3 has a rectangular cross section, and the spindle head (elevating slider) 6 has side surfaces 8 and 9 extending rearward on both sides of the front surface portion 7, and the front surface 3 a and the side surface 3 b of the moving column 3. The cross section is formed in a U-shape so as to face each other.

  The spindle head 6 can be moved up and down by four guide rails including a pair of elevating guide rails 10 and 10 attached to the front surface 3a of the moving column 3 and elevating guide rails 11 and 11 attached to the left and right side surfaces 3b. Guided. On the side surface 3b of the moving column 3, a stator (fixed magnet) 12a of the elevating linear motor 12 is provided on the inner side surface of the side surface portions 8 and 9 of the spindle head 6 (the surface facing the side surface 3b of the moving column 3). A mover (coil) 12b is attached, and an elevating linear motor 12 which is a drive means for elevating the spindle head 6 is configured between the stator 12a and the mover 12b, and an excitation current is supplied to the mover 12b. By flowing it, a vertical linear motor thrust is generated between the opposed stator 12a and the spindle head 6 is moved up and down. The spindle head 6 and the moving column 3 may be moved by a feed screw mechanism using a ball screw.

  A spindle support portion 15 projects from the spindle head 6 in the front-rear direction. A main shaft 16 is rotatably provided on the main shaft support portion 15 and is rotated by a main shaft motor M. The portion of the spindle support 15 that protrudes rearward from the spindle head 6 moves up and down in a long hole 17 that penetrates the moving column 3 in the front-rear direction when the spindle head 6 moves up and down.

  Brackets 18 and 19 for attaching a brake rod are fixed to the left and right sides of the left and right side surfaces 3b and 3b of the moving column 3 so as to protrude outward from the moving column 3 to the left and right, respectively. A brake rod 20 in the vertical direction (parallel to the moving direction of the spindle head 6) is attached between the brackets 18 and 19 facing vertically on the right (or left) side of the moving column 3, and thus the spindle head 6 A pair of brake rods 20 are arranged on both the left and right outer sides. On the other hand, when the brake rod 20 penetrates and the energization of the elevating linear motor 12 is cut off, the brake device 21 that grips the brake rod 20 from the outside in the radial direction to prevent the spindle head 6 from falling is provided with the spindle head. 6 are attached integrally to the upper surfaces of the left and right side surface portions 8 and 9 via attachment brackets 22 respectively. In FIG. 1, the left brake device 21 is omitted. In addition, the present invention is not limited to the configuration of the brake device 21, and detailed description thereof is omitted here.

  Further, as shown in FIG. 2, at the rear of the brake device 21, the left and right side surfaces 3b of the moving column 3, and the left and right sides of the upper surface are respectively balanced cylinders so as to protrude outwardly from the moving column 3 respectively. Mounting brackets 23 and 24 are fixed. In the embodiment of the present application, two balance cylinders 25 and 25 are respectively arranged in the front and rear between the balance cylinder mounting brackets 23 and 24 that are vertically opposed to the left and right of the moving column 3. The balance cylinder 25 is a rodless cylinder, and an external moving body (piston mount) 27 integrated with the piston 26 connected to the left and right side surfaces 8 and 9 of the spindle head 6 is moved up and down following the elevation of the spindle head 6. Stands vertically to move in the direction. Each rodless cylinder 25 is connected with a pneumatic control device 28 to be described later to constitute a balance device 29.

  In FIG. 3, the cylinder tube 30 of the rodless cylinder 25 is formed with a non-circular (oval) cylinder hole 31 over the entire length in the axial direction and a slit 32 over the entire length in the axial direction. . Both ends of the cylinder tube 30 (shown only on one side (upper end portion in FIG. 3)) are closed with an end cap 33 to form a cylinder chamber 34. The end caps 33 are attached to both ends of a thin flexible inner seal band 35 and an outer seal band 36 that seal the slit 32 from the inside and outside by fitting fitting pins 37 into pin holes 38.

  A piston 26 constituted by connecting piston ends 40 and 41 to both sides of a piston yoke 39 is fitted into the cylinder chamber 34 so as to be movable in the axial direction. 28 is divided into a lower pressurizing cylinder chamber 42 to which 28 is connected and an upper discharge cylinder chamber 43 that is opened to atmospheric pressure. The piston yoke 39 has a slit side portion (upper portion in FIG. 3) narrowed and protrudes from the slit 32 to the outside, and expands to the left and right (perpendicular to the paper surface in FIG. 3) outside the cylinder tube 30. The inner seal band 35 and the outer seal band 36 are guided.

  A packing mounting groove 44 is formed in the piston ends 40 and 41 at both ends of the piston 26, and a piston packing 45 is mounted in the packing mounting groove 44 of the piston end 40 on the pressure side cylinder chamber 42 side. As shown in FIG. 4, the piston packing 45 includes inner and outer lips 46 and 47, and the outer shape of the piston packing 45 matches the cross-sectional shape of the cylinder hole 31 to form an oval shape. Further, in the packing mounting groove 44, lubricant holding rings 48 and 48 are mounted so that the piston packing 45 is sandwiched between front and rear of the piston packing 45 in the cylinder axial direction (up and down in the cylinder axial direction). The lubricant retaining ring 48 is made of a fiber assembly material in which synthetic fibers such as polyester and rayon are fused with a rubber elastic body, and can hold oil, grease, or the like between the synthetic fibers fused with the rubber elastic body. Has a lubricant holding function. As the lubricant retaining ring 48, for example, a soft wiper (trade name) can be used. The lubricant retaining ring 48 is slidably pressed against the inner surface of the cylinder tube 30 and the inner surface of the inner seal band 35 by the elasticity of the rubber elastic body. The lubricant retaining ring 48 is preliminarily impregnated with a large amount of grease, and when moving in the cylinder tube 30 filled with grease in advance, if there is a break in the oil film in the cylinder tube 30, Grease is supplied in the middle. The piston end 41 on the other discharge side cylinder chamber 43 side of the piston 26 is not equipped with a piston packing and a lubricant retaining ring.

  A pressure air supply / discharge port 49 is formed in the end cap 33 on the pressure side cylinder chamber 42 side (FIG. 5). A compressed air control device 28 is connected to the supply / discharge port 49. As shown in FIG. 5, the compressed air control device 28 includes a factory air source 50 as a pressurized fluid supply source and a supply / discharge circuit 51. The supply / discharge circuit 51 connects the factory air source 50 and the supply / discharge port 49 of the rodless cylinder 25, and includes a filter 53, a pressure reducing valve 54, a check valve 55, and a tank 52 from the factory air source 50 side. Yes. The tank 52 has a volume capable of absorbing fluctuations in air pressure (insufficient pressure and excessive pressure) in the pressure side cylinder chamber 42. The supply / discharge circuit 51 supplies the compressed air from the factory air source 50 to which the supply air pressure is set by the pressure reducing valve 55 to the pressurizing cylinder chamber 42 via the tank 52, and the pressurizing cylinder chamber of the rodless cylinder 25. Exhaust gas from 42 is returned to the tank 52. The end cap 33 on the discharge side cylinder chamber 43 side is provided with a first port 57 that opens the discharge side cylinder chamber 43 to atmospheric pressure, and the first port 57 is provided with a filter 58.

  In the machine tool 1 configured as described above, when the linear motor 12 is electrically controlled when the workpiece W is machined and the spindle head 6 repeats random up and down and temporary stop at a high speed, the balance device 29 causes the rodless cylinder 25 to The piston 26 moves up and down following the movement of the spindle head 6 and stops. At this time, when the spindle head 6 is raised, the piston 26 is raised, so that the discharge side cylinder chamber 43 is reduced and air is exhausted to the atmosphere via the first port 57, and the pressure side cylinder chamber 42 is enlarged and pressurized. Becomes lower than the set pressure of the pressure reducing valve 54, and the compressed air flows into the pressurizing side cylinder chamber 42 via the air supply circuit 51, and the pressure of the compressed air acts on the piston 26 to urge the piston 26 upward. On the other hand, when the spindle head 6 is lowered, the piston 26 is lowered, so that the discharge side cylinder chamber 43 is enlarged and air is sucked from the atmosphere through the first port 57, and the pressure side cylinder chamber 42 is reduced and the exhaust is stored in the tank. By returning to 52, the pressure fluctuation in the pressure side cylinder chamber 42 is absorbed by the large animal pressure capacity of the tank 52. Thereby, the weight balance of the spindle head 6 is maintained.

  Further, when the spindle head 6 is temporarily stopped, the piston 26 is also stopped. At this time, the oil film of grease formed on the inner seal band 35 and the inner surface of the cylinder chamber 34 is cut by the outer lip 47 of the piston packing 45, An oil film is cut halfway. However, when the piston 26 moves following the random elevation of the spindle head 6, the lubricant retaining rings 48 on both sides of the piston packing 45 of the piston end 40 pass through the oil film halfway cut, and the oil film halfway cuts the lubricant. The grease impregnated in the retaining ring 48 is supplied, and the breakage of the oil film is repaired with the supplied grease. Therefore, since the oil film is cut off halfway and the piston packing 45 is provided only at one location of the piston 26, the resistance of the piston packing 45 is reduced. Smoothly done. In particular, when the raising / lowering driving means is a linear motor with high speed and weak force, the rodless cylinder is preferable because it does not affect the smooth raising / lowering of the spindle head.

  Next, a second embodiment will be described with reference to FIGS. In the first embodiment, the piston 26 is provided with a second port 59 for opening the discharge side cylinder chamber 43 to the atmospheric pressure. The same reference numerals are given to the same parts as in the first embodiment. Description is omitted. The second port 59 avoids the inner seal band 35 in the piston yoke 39 and the passage 61 formed by the passage 60 provided in the piston end 41 on the discharge side cylinder chamber 43 side, the piston yoke 39 and the inner surface of the cylinder hole 31. And a passage 62 opened from the piston mount 27 to the atmospheric pressure.

  When the spindle head 6 moves up and down at random, air is supplied and discharged into the discharge side cylinder chamber 43 through the first port 57 and the second port 59. Thus, when the size of the first port 57 is limited or when the rodless cylinder 25 is long, etc., when the supply and discharge from the discharge side cylinder chamber 43 cannot be sufficiently performed only by the first port 57, the discharge side cylinder chamber Although the pressure at 43 is increased, the supply / discharge amount can be increased and the supply / discharge speed can be increased by providing the second port 59, so that the piston 26 moves at a high speed following the high-speed movement of the spindle head 6. However, the pressure increase in the discharge side cylinder chamber 43 is small, the resistance to the piston 26 is not increased, and the spindle head 6 is smoothly moved.

  Next, a third embodiment will be described. The same parts as those of the first embodiment are denoted by the same reference numerals and the description thereof is omitted. This uses a standard rodless cylinder as a balance cylinder. Referring to FIG. 3, the standard rodless cylinder includes a piston packing 45 in the packing mounting grooves 44 of the piston ends 40 and 41 at both ends of the piston 26, but does not include a lubricant retaining ring 48. It is a configuration. As in the first embodiment, in order to reduce the sliding resistance of the piston 26 so as not to affect the smooth raising and lowering of the spindle head 6, the piston end 41 on the discharge side cylinder chamber 43 side in the standard rodless cylinder is used. The piston packing 45 is attached only to the piston end 40A on the pressurization side cylinder chamber 42 side without attaching the piston packing, and the piston end 40A on the pressurization side cylinder chamber 42 side is lubricated in the longitudinal direction of the cylinder axis of the piston packing 45. An agent holding ring 48A is attached to form a balance cylinder.

  As shown in FIG. 8, the lubricant retaining ring 48A has a ring mounting groove 63 additionally machined on the front side in the cylinder axial direction of the packing mounting groove 44A of the piston end 40A on the pressure side cylinder chamber 42 side, and a cross-sectional shape on the rear side. Is mounted in a ring mounting groove 64a formed by a stepped portion on the piston packing 45 side in which a stepped ring mounting plate 64 is additionally mounted on the rear side in the cylinder axial direction of the packing mounting groove 44A. The configuration is similar. As shown in FIG. 9, the ring mounting plate 64 is provided with a slit 64b for enabling mounting in the packing mounting groove 44A. Of course, a second port may be additionally formed in the piston 26 as in the second embodiment. In this way, if the standard rodless cylinder for mass production is additionally used, the piston end is made of plastic or other synthetic resin, so it is an expensive die for the piston end with a ring mounting groove. It is preferable to use an inexpensive standard rodless cylinder.

It is a front view of a machine tool. It is a top view of FIG. It is a longitudinal cross-sectional view of a rodless cylinder. It is an enlarged view of the piston end of the pressure side cylinder chamber side. It is explanatory drawing which shows a balance apparatus. It is a longitudinal cross-sectional view of the rodless cylinder which shows a 2nd Example. It is the VII-VII sectional view taken on the line of FIG. It is an enlarged view of the piston end by the side of a pressure side cylinder chamber which shows a 3rd Example. It is a front view of a ring mounting plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Machine tool 3 Column 6 Spindle head 12 Elevating drive means (linear motor for raising / lowering)
25 Balance cylinder (rodless cylinder)
26 Piston 27 External moving body (piston mount)
29 Balancing device 30 Cylinder tube 33 End cap 34 Cylinder chamber 42 Pressure cylinder chamber 43 Discharge cylinder chamber 44, 44A Packing groove 45 Piston packing 48, 48A Lubricant holding ring 57 First port 59 Second port 63, 64a Ring Mounting groove 64 Ring mounting plate

Claims (3)

  A rodless cylinder used as a balance cylinder in a balance device of a machine tool having a balance cylinder for guiding a spindle head to a column to be moved up and down by an elevating drive means and biasing the spindle head upward. In the cylinder, an external moving body outside the cylinder tube connected to a piston fitted in the cylinder chamber of the cylinder tube so as to be movable in the axial direction is connected to the spindle head, and the piston is a fluid that urges the spindle head upward. A balance device for a machine tool, wherein a piston packing is provided only at an end on the pressure side cylinder chamber on which pressure acts, and a lubricant holding ring having a lubricant holding function is provided before and after the piston packing in the axial direction. Rodless cylinder for use.   The pressure side cylinder chamber of the rodless cylinder and the discharge side cylinder chamber on the opposite side across the piston are brought to atmospheric pressure by the first port provided on the end cap and the second port provided on the external moving body via the piston. The rodless cylinder for a balance device of a machine tool according to claim 1, wherein the rodless cylinder is opened.   The piston has a standard structure with at least a packing mounting groove for mounting the piston packing at both ends in the cylinder axial direction, and is lubricated before and after the packing mounting groove on the pressure side cylinder chamber side of the piston in the cylinder axial direction. Add a ring mounting groove for mounting the agent retaining ring, or additionally mount a ring mounting plate with a ring mounting groove, mount a piston packing in the packing mounting groove, and lubricate the ring mounting grooves before and after the piston packing. The rodless cylinder for a balance device of a machine tool according to claim 1 or 2, wherein a retaining ring is attached.

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