JP5045487B2 - Balancing machine and aligning method thereof - Google Patents

Description

  The present invention relates to a balance cylinder device mounted on a machine tool and an alignment method thereof.

  When moving a moving body holding a workpiece or tool of a machine tool up and down by the moving device, the balance cylinder device always applies an appropriate upward force to the moving body to balance all or part of the weight of the moving body. It is something to be made. The moving body is fixed to one of the cylinder and the piston of the balance cylinder device, and the base is fixed to the other of the cylinder and the piston. Pressure air is supplied to the cylinder chamber formed between the piston and the cylinder. By increasing / decreasing the supply amount of the pressure air to the cylinder chamber, the cylinder chamber is enlarged / reduced, and the vertical movement amount of the moving body with respect to the base is adjusted (Patent Document 1).

By the way, when the workpiece is precisely processed, it is necessary to adjust the relative position between the tool and the workpiece with high accuracy. For this reason, it is desired that there is no contact between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder. In such a non-contact balance cylinder device, in order to reduce the amount of air outflow from the gap between the piston and the cylinder, the width of the gap is set to be very narrow, 20 to 30 μm. Therefore, when the piston and the cylinder are assembled in a processing machine for ultra-precision machining in a state where the relative position between the piston and the cylinder is slightly shifted from the same axis, the piston and the cylinder may come into contact with each other. In order to prevent contact between the piston and the cylinder, when assembling the piston and the cylinder to the processing machine, it is necessary to align the balance cylinder device so that the piston and the cylinder are accurately positioned on the same axis. Therefore, the assembly work of the piston and the cylinder is a very difficult work.
JP 2004-209550 A

  The present invention has been made in view of such circumstances, and provides a balance cylinder device capable of aligning a piston and a cylinder accurately and coaxially with a simple configuration, and an alignment method therefor. This is the issue.

  In order to solve the above-mentioned problem, the balancing method of the balance cylinder device according to the first aspect of the present invention includes a cylinder mounted on a moving member that is mounted on a base of a machine tool so as to be vertically movable and is moved up and down by a moving means. One of the piston and the cylinder of the device is fixed, the other of the piston and the cylinder is fixed to the base by the fastening means, and the movement is performed by supplying pressure fluid to the cylinder chamber formed between the piston and the cylinder. In the method of aligning the piston and the cylinder of a balance cylinder device for supporting the weight of a member, the fastening means is loosened to allow relative movement between the base and the other of the piston and the cylinder, and the piston Compressed air is supplied to an air bearing formed on the outer peripheral surface of the piston or the inner peripheral surface of the cylinder. , A centering step for automatically aligning the fitting gap between the piston and the cylinder over the entire circumference, and after the automatic alignment, the fastening means is fastened to fasten the base and the piston. And a fastening step for restricting relative movement with the other of the cylinders.

  According to a second aspect of the present invention, in a portion of the cylinder facing the cylinder chamber, an opening that opens the cylinder chamber during the self-alignment, and a lid that closes the opening so as to be openable and closable. In the alignment step, the lid is opened to open the cylinder chamber to the atmosphere.

  The invention according to claim 3 is characterized in that, in the alignment step, a fluid supply pipe which is formed in the cylinder or the piston and supplies the pressure fluid to the cylinder chamber is opened to the atmosphere.

  In the balance cylinder device according to the invention according to claim 4, one of the piston and the cylinder of the cylinder device is fixed to the moving member that is mounted on the base of the machine tool so as to be movable in the vertical direction and is moved up and down by the moving means, In the balance cylinder device in which the other of the piston and the cylinder is fixed to a base, and pressure fluid is supplied to a cylinder chamber formed between the piston and the cylinder to support the weight of the moving member. Formed on the outer peripheral surface of the piston to be fitted to the cylinder or the inner peripheral surface of the cylinder, and supplied with compressed air, the fitting gap between the piston and the cylinder is automatically and evenly adjusted over the entire circumference. A centering air bearing, and during the self-alignment by the air bearing, the relative movement between the base and the other of the piston and the cylinder is allowed. Is sintered, characterized in that it comprises a fastening means for restricting the relative movement.

  According to a fifth aspect of the present invention, in a portion of the cylinder facing the cylinder chamber, an opening that opens the cylinder chamber during the self-alignment, and a lid that closes the opening so as to be openable and closable. Is provided.

  According to the first aspect of the present invention, compressed air is supplied to the air bearing formed on the outer peripheral surface of the piston or the inner peripheral surface of the cylinder while allowing the other of the piston and the cylinder to move relative to the base. By doing so, the fitting clearance between the piston and the cylinder is made uniform over the entire circumference. For this reason, alignment of the balance cylinder device can be performed so that the piston and the cylinder are accurately positioned on the same axis.

  Further, when aligning the balance cylinder device, it is only necessary to supply compressed air from the air bearing to the fitting gap, and it is easy and labor-saving.

  According to the second aspect of the present invention, when the lid is opened to open the opening of the cylinder, the cylinder chamber is opened to the atmosphere, and the air pressure in the cylinder chamber is reduced. In this state, by supplying the compressed air to the air bearing, the compressed air can be prevented from flowing back from the cylinder chamber to the fitting gap without being pushed back in the cylinder chamber. Therefore, a smooth flow of compressed air can be formed in the fitting gap from the air bearing toward both ends of the fitting gap in the axial direction. Therefore, the fitting gap can be made more uniform over the entire circumference.

  According to the third aspect of the present invention, the fluid supply pipe is opened to the atmosphere in the alignment step. For this reason, the compressed air which has circulated from the fitting gap to the cylinder chamber is led out to the atmosphere side through the fluid supply pipe. Therefore, the cylinder chamber can be opened to the atmosphere, and the backflow of compressed air from the cylinder chamber to the fitting gap can be prevented. Therefore, a smooth flow of compressed air can be formed in the fitting gap. Therefore, the fitting gap can be made more uniform over the entire circumference.

  According to the fourth aspect of the present invention, the air bearing is formed on the outer peripheral surface of the piston or the inner peripheral surface of the cylinder. For this reason, by supplying the compressed air to the air bearing while allowing the other of the piston and the cylinder to move relative to the base, the fitting clearance between the piston and the cylinder is automatically and uniformly distributed over the entire circumference. Can be aligned. Therefore, the piston and the cylinder can be accurately positioned on the same axis.

  Further, in the automatic alignment, it is only necessary to provide an air bearing in at least one of the piston and the cylinder, and the configuration is simple.

  According to the fifth aspect of the present invention, when the lid is opened and the opening of the cylinder is opened, the cylinder chamber is opened to the atmosphere and the air pressure is lowered. In this state, by supplying compressed air to the air bearing, the backflow of the compressed air from the cylinder chamber to the fitting gap can be prevented, and a smooth flow of the compressed air can be formed in the fitting gap. Therefore, the fitting gap can be made more uniform over the entire circumference.

  Embodiments of the present invention will be described with reference to the drawings. The balance cylinder device according to the present embodiment is provided in a workpiece moving device of an ultra-precision machining device as a processing machine. As shown in FIGS. 1 and 2, the ultraprecision machining apparatus 9 includes a bed 2, a workpiece moving device 91 that moves the workpiece W on the Y axis and the Z axis, and rotates the workpiece T around the C axis, and the tool T as X A tool moving device 92 that moves on the axis and rotates around the B axis.

  The workpiece moving device 91 is mounted on the bed 2 and can move in the Z-axis direction, the column 3 as a base standing on the table 90, and mounted on the column 3 and moved in the Y-axis direction. A slide table 93 as a movable member, a spindle head 94 fixed to the slide table 93, and a spindle provided with a chuck that is supported by the spindle head 94 so as to be rotatable around the C axis and holds the workpiece W at the tip. 99.

  The bed 2 includes a Z-axis linear motor magnet (not shown) and a Z-axis guide 23 that extend in the Z-axis direction, and an X-axis linear motor magnet (not shown) and an X-axis guide 22 that extend in the X-axis direction. It has. Both the Z-axis and the X-axis are in the plane direction and are orthogonal to each other.

  The table 90 has a Z-axis linear motor coil (not shown) disposed opposite to the Z-axis linear motor magnet on the bed 2 and a sliding body (not shown) movably supported by the Z-axis guide 23 on the bed 2. ) And are fixed. By energizing the Z-axis linear motor coil, the table 90 moves in the Z-axis direction while being guided by the Z-axis guide 23.

  The column 3 has a standing part 31 standing on the table 90 and a side part 32 fixed to a side surface of the standing part 31. As shown in FIG. 1, a Y-axis linear motor magnet 98 a and a Y-axis guide 98 b extend in the Y-axis direction (vertical direction) on the side portion 32 of the column 3. Further, the slide table 93 is provided with a Y-axis linear motor coil 98c and a sliding body 98d disposed to face the Y-axis linear motor magnet 98a and the Y-axis guide 98b, respectively. By energizing the Y-axis linear motor coil 98c, the slide table 93 moves in the Y-axis direction while being guided by the Y-axis guide 98b via the sliding body 98b. The Y-axis linear motor magnet 98a, the Y-axis guide 98b, the Y-axis linear motor coil 98c, and the sliding body 98d constitute moving means 98 that moves the slide table 93 in the Y-axis direction.

  As shown in FIGS. 2 and 3, the balance cylinder device 1 that supports the weight of the slide table 93 is disposed on the side portion 32 of the column 3. The balance cylinder device 1 includes a piston 4 fixed on a side portion 32 of a column 3, a cylinder 5 fixed to a side surface of a slide table 93, and a cylinder air as a fluid supply pipe disposed inside the piston 4. It has a supply pipe 6 and a bearing air supply pipe 7 disposed inside the piston 4.

  The piston 4 has a cylindrical shape, and its axial direction coincides with the Y-axis direction (vertical direction) of the ultraprecision machining apparatus 9. And the flange part 40 which protrudes to radial direction is provided in the axial direction base end part of piston 4. As shown in FIG. The flange portion 40 is fastened to the upper portion of the side portion 32 by fastening means 42 such as bolts. The outer peripheral surface 41 of the piston 4 has a substantially circular cross section, and has a general portion 41a and a bearing portion 41b that is positioned closer to the tip in the axial direction than the general portion 41a and has a larger diameter than the general portion 41a. An air bearing 44 in which a bearing air supply pipe 7 described later is opened is formed in the bearing portion 41b with an interval in the circumferential direction. In other words, the air bearing 44 is formed on the periphery of the opening of the bearing air supply pipe 7 in the bearing portion 41 b of the outer peripheral surface 41 of the piston 4. As shown in FIG. 4, a cylinder 5 is coaxially disposed on the outer peripheral side of the piston 4 so as to be slidable in the axial direction. Since the cylinder 5 is fixed to the slide table 93 that can be moved in the Y-axis direction by the moving means 98 and the movement in the plane direction is restricted, the movement of the cylinder 5 in the plane direction is restricted.

  The cylinder 5 has a bottomed cylindrical shape, and has a body 50 having openings 50a and 50b at both ends in the axial direction and a lid 52. The inner peripheral surface 51 of the main body 50 of the cylinder 5 has a circular opening cross section, and is fitted in a non-contact manner with respect to the outer peripheral surface 41 of the piston 4. An annular gap 80 is formed between the inner peripheral surface 51 of the main body 50 and the outer peripheral surface 41 of the piston 4. An opening 50 a formed at one end in the axial direction of the cylinder 5 is covered with a lid 52. A cylinder chamber 81 is formed between one end of the cylinder 5 in the axial direction, the lid 52 and the piston 4. The cylinder chamber 81 is enlarged or reduced by an axial slide of the cylinder 5. As shown in FIG. 3, an air opening end 83 that opens the annular gap 80 to the atmosphere side is formed between the piston 50 and the opening 50 b formed at the other end in the axial direction of the cylinder 5. Yes.

  As shown in FIGS. 3 and 4, the annular gap 80 formed between the piston 4 and the cylinder 5 includes a general gap 84 located on the atmosphere opening end 83 side and a cylinder chamber 81 side from the general portion 84. The fitting gap 85 is narrower in the radial direction than the general gap 84. The general gap 84 is formed between the inner peripheral surface 51 of the main body 50 of the cylinder 5 and the general portion 41 a of the outer peripheral surface 41 of the piston 4. The fitting gap 85 is formed between the inner peripheral surface 51 of the main body 50 of the cylinder 5 and the bearing portion 41 b of the outer peripheral surface 41 of the piston 4. The fitting gap 85 is a very narrow space having a radial width of usually 20 to 30 μm, and the cylinder 5 and the piston 4 are fitted to each other in the fitting gap 85. For this reason, the amount of air flowing out from the cylinder chamber 81 when the balance cylinder device 1 is operated is determined by the area of the opening cross section of the fitting gap 85.

  As shown in FIG. 3, the cylinder air supply pipe 6 extends inside the piston 4 along the axial direction thereof. One end 6 a in the longitudinal direction of the cylinder air supply pipe 6 is open to the cylinder chamber 81, and the other end 6 b is connected to a cylinder air circulation pipe 69 provided inside the column 3. The cylinder chamber 81 is adjusted by adjusting the amount of air supplied as pressure fluid supplied from the cylinder air supply pipe 6 to the cylinder chamber 81 in consideration of the amount of air outflow from the fitting gap 85 to the atmosphere open end 83. The air pressure is adjusted.

  The bearing air supply pipe 7 includes a first passage 71 disposed in the axial center of the piston 4 and extending linearly in the axial direction, and a second passage 72 connected to the first passage 71 and extending in the radial direction of the piston 4. Consists of. An upper end 71 a in the longitudinal direction of the first passage 71 is closed by a stopper 71 c so that compressed air is not directly supplied from the bearing air supply pipe 7 to the cylinder chamber 81. A lower end 71 b in the longitudinal direction of the first passage 71 is connected to a bearing air supply pipe 79 provided inside the side portion 32. The second passage 72 is connected to an intermediate portion 71d between the upper end 71a and the lower end 71b of the first passage 71. As shown in FIG. 5, the second passage 72 extends radially in the radial direction of the piston 4 around the axis center of the piston 4, that is, radially at the same angle (90 °) in the four directions. . An air pocket 72 a of the air bearing 44 formed in the bearing portion 41 b of the outer peripheral surface 41 of the piston 4 is opened on the radially outer side of the second passage 72. Accordingly, the air pockets 72a are arranged at four equal intervals in the circumferential direction of the piston 4. 5 and 6, in the second passage 72, an orifice 72b that narrows the radial cross section of the second passage 72 is press-fitted inside each air pocket 72a, whereby the air bearing 44 is configured. ing.

  As shown in FIGS. 2 and 3, the main body 50 of the cylinder 5 is fixed to the slide table 93 on the outer peripheral surface 53. A spindle head 94 that extends toward the tool T in the Z-axis direction is mounted on the slide table 93. A spindle 99 is supported by the spindle head 94 so as to be rotatable in parallel with the Z axis, and a chuck for holding the workpiece W is mounted on the tip of the spindle 99 in the axial direction. The main shaft 99 is rotationally driven by a DD motor or the like around a central axis (C axis) extending in the Z-axis direction.

  As shown in FIG. 1, the tool moving device 92 disposed in the ultra-precision machining device 9 is mounted on the bed 2 and mounted on the table 95 and a table 95 that can be moved in the X-axis direction. The rotary table 96 is rotatable about the B axis (vertical axis), and the tool holder 97 is fixed on the rotary table 96 and holds the tool T.

  The table 95 has an X-axis linear motor coil (not shown) disposed opposite to the X-axis linear motor magnet on the bed 2 and a sliding body (not shown) movably supported by the X-axis guide 22 on the bed 2. ) And are fixed. By energizing the X-axis linear motor coil, the table 95 moves in the X-axis direction while being guided by the X-axis guide 22. The rotary table 96 is rotationally driven by a DD motor or the like around the vertical axis (B axis).

  The workpiece W is moved in the Z-axis direction and the Y-axis direction by the workpiece moving device 91 and rotated around the C-axis. The tool T is moved in the X-axis direction and rotated about the B-axis by the tool moving device 92. The respective linear motors and DD motors that drive the movement and rotation of the workpiece moving device 91 and the tool moving device 92 are controlled so that the tool T and the workpiece W move to relative positions at a desired relative speed. Controlled by the device.

  In aligning the balance cylinder device, first, the fastening means 42 shown in FIG. 3 is loosened so that the piston 4 can move relative to the column 3. As a result, the piston 4 can move relative to the cylinder 5 in the plane direction. Further, the lid 52 of the cylinder 5 is opened, and the cylinder chamber 81 is opened to the atmosphere. Then, compressed air is supplied from the bearing air supply pipe 7 provided in the piston 4 to the four air bearings 44 of the piston 4 via the second passages 72. As shown in FIG. 5, when compressed air is supplied to each air bearing 44, the air bearing 44 having a narrow radial width of the fitting gap 85 between the piston 4 and the cylinder 5 (the two-dot chain line in FIG. 5). 44a) has a higher air pressure than other wide air bearings 44 (reference numeral 44b indicated by a two-dot chain line in FIG. 5). For this reason, the piston 4 is pressed by the high air pressure by the narrow air bearing 44 and moves toward the other wide air bearing 44 so that the air pressures are equal to each other. As a result, the radial width becomes uniform over the entire circumference of the fitting gap, and the piston 4 and the cylinder 5 are automatically aligned coaxially.

  After the piston 4 is positioned coaxially with the cylinder 5, the fastening force of the fastening means 42 is increased and the piston 4 is finally fastened to the column 3. Thereby, the relative movement of the piston 4 with respect to the column 3 is restricted, and the relative movement of the cylinder 5 in the plane direction is restricted. Thereafter, the supply of compressed air from the bearing air supply pipe 7 to the air bearing 44 is stopped, and the opening 79a on the atmosphere opening side of the bearing air flow passage 79 communicating with the bearing air supply pipe 7 is plugged. The opening 52a of the main body 50 is closed by the lid 52, and the cylinder chamber 81 is closed. Thus, the alignment operation of the balance cylinder device 1 is completed.

  Next, when the balance cylinder device 1 is operated, air is supplied from the cylinder air supply pipe 6 so that the balance cylinder device 1 supports the weight of the moving member including the cylinder 5, the slide table 93, the spindle head 94, and the like. Supply to chamber 81. At this time, when the air supply amount is increased, the air pressure in the cylinder chamber 81 is increased, and when the air supply amount is decreased, the air pressure in the cylinder chamber 81 is decreased.

  In this embodiment, while allowing the piston 4 to move relative to the column 3, compressed air is supplied to the air bearing 44, and the fitting gap 85 between the piston 4 and the cylinder 5 is extended over the entire circumference. Evenly. For this reason, alignment of the balance cylinder device 1 can be performed so that the piston 4 and the cylinder 5 are accurately positioned on the same axis.

  In order to align the balance cylinder device 1, it is only necessary to provide the bearing air supply pipe 7. The balance cylinder device has a simple configuration and only supplies compressed air from the bearing air supply pipe 7 to the air bearing 44. 1 alignment can be performed, and it is easy and labor-saving.

  When the lid 52 is opened and the opening 50a of the main body 50 of the cylinder 5 is opened, the cylinder chamber 81 is opened to the atmosphere, and the air pressure in the cylinder chamber 81 is lowered. By supplying the compressed air to the air bearing 44 in this state, the compressed air is not pushed back in the cylinder chamber 81, and the compressed air can be prevented from flowing backward from the cylinder chamber 81 to the fitting gap 85. Therefore, a smooth flow of compressed air is caused to flow into the fitting gap 85 from the air bearing 44 to the opening 50a on the cylinder chamber 81 side and from the air bearing 44 to the atmosphere opening end 83 on the opposite side to the cylinder chamber 81 side. Can be formed. Therefore, the fitting gap 85 can be made more uniform over the entire circumference.

  In the above embodiment, as shown in FIG. 5, the second passage 72 of the bearing air supply pipe 7 extends in four directions around the axial center of the piston 4, but is not limited to this, and in three directions, Or you may extend radially in five directions or more. The greater the direction in which the second passage 72 extends, the greater the number of air bearings 44 that communicate with the second passage 72. In providing a plurality of air bearings 44, it is preferable to arrange all the air bearings 44 at equal intervals in the circumferential direction of the outer peripheral surface 41 of the piston 4. Thereby, compressed air can be supplied uniformly over the entire circumference of the fitting gap 85.

  In the above embodiment, the bearing air supply pipe 7, the first passage 72, the air pocket 72 a and the orifice 72 b are provided in the piston 4, but may be provided in the cylinder 5. Further, the cylinder air supply pipe 6 may be provided in the cylinder 5.

  In the above embodiment, the piston 4 is fixed to the column 3 and the cylinder 5 is fixed to the slide table 93 that is a moving member. However, the cylinder 5 is fixed to the column 3 and the piston 4 is fixed to the slide table 93. It may be fixed to.

  Further, in the above embodiment, as shown in FIG. 3, when supplying compressed air to the fitting gap 85, the lid 52 is opened and the cylinder chamber 81 is opened. The cylinder chamber 85 may be opened to the atmosphere by opening the cylinder air supply pipe 6 to the atmosphere with the opening 50a of the main body 50 closed.

  Further, in the above embodiment, the balance cylinder device 1 is mounted on the work moving device 91, but the balance cylinder device 1 can also be mounted on the tool moving device 92.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention described in the claims. Of course there is.

1 is a plan view of an ultra-precision machining apparatus equipped with a balance cylinder device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of a tool moving device equipped with a balance cylinder device according to the first embodiment. 1 is a cross-sectional view of a balance cylinder device according to a first embodiment. It is a principal part expanded sectional view of FIG. It is AA arrow sectional drawing of FIG. It is a principal part expanded sectional view of FIG.

Explanation of symbols

1: Balance cylinder device, 2: Bed, 3: Column, 4: Piston, 5: Cylinder, 6: Cylinder air supply pipe, 7: Bearing air supply pipe, 9: Ultra-precision machining device, 41: Outer peripheral surface of piston, 41a: General part, 41b: Bearing part, 44: Air bearing, 50: Main body, 50a, 50b: Opening part, 51: Inner peripheral surface of cylinder, 52: Cover body, 71: First passage, 72: Second passage 72a: air pocket, 72b: orifice, 80: cylindrical gap, 81: cylinder chamber, 83: open end, 84: general gap, 85: fitting gap, 90: table, 91: workpiece moving device, 92: tool movement Device: 93: Slide table, 94: Spindle head, 95: Table, 96: Rotary table, 97: Tool holder, 98: Moving means, 99: Spindle, W: Workpiece, T: Tool

Claims (5)

One of the piston and the cylinder of the balance cylinder device is fixed to a moving member mounted on a machine tool base so as to be movable in the vertical direction and moved up and down by the moving means, and the other of the piston and cylinder is fastened by the fastening means. A method of aligning the piston and the cylinder of the balance cylinder device that is fixed to a table and supplies pressure fluid to a cylinder chamber formed between the piston and the cylinder to support the weight of the moving member In
The fastening means is loosened to allow relative movement between the base and the other of the piston and the cylinder, and is formed on the outer peripheral surface of the piston or the inner peripheral surface of the cylinder where the piston and the cylinder are fitted. A self-aligning process of supplying compressed air to the air bearing and automatically aligning the fitting gap between the piston and the cylinder over the entire circumference;
After the automatic alignment, a fastening step of fastening the fastening means to restrict relative movement between the base and the other of the piston and the cylinder;
A method of aligning a balance cylinder device, comprising: The portion defining the cylinder chamber in the cylinder is provided with an opening for opening the cylinder chamber during the automatic alignment and a lid for closing the opening so as to be openable and closable.
2. The alignment method for a balance cylinder device according to claim 1, wherein in the alignment step, the lid is opened to open the cylinder chamber to the atmosphere.   2. The alignment method for a balance cylinder device according to claim 1, wherein, in the alignment step, a fluid supply pipe formed in the cylinder or the piston and supplying the pressure fluid to the cylinder chamber is opened to the atmosphere. One of the piston and cylinder of the balance cylinder device is fixed to a moving member that is mounted on a machine tool base so as to be movable in the vertical direction and is moved up and down by a moving means, and the other of the piston and cylinder is fixed to the base. In the balance cylinder device for supporting the weight of the moving member by supplying a pressure fluid to a cylinder chamber formed between the piston and the cylinder,
Formed on the outer peripheral surface of the piston or the inner peripheral surface of the cylinder where the piston and the cylinder are fitted to each other, compressed air is supplied, and the fitting gap between the piston and the cylinder is evenly distributed over the entire circumference. A self-aligning air bearing,
Fastening means for allowing relative movement between the base and the other of the piston and the cylinder at the time of automatic alignment by the air bearing, and being fastened after the automatic alignment and restricting the relative movement;
A balance cylinder device comprising: The part defining the cylinder chamber in the cylinder is provided with an opening for opening the cylinder chamber during the automatic alignment and a lid for closing the opening so as to be openable and closable. 5. The balance cylinder device according to claim 4, wherein

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