JP2006102903A - Machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent any increase in size of a machine tool while completely restraining mechanical parts in the periphery from being magnetized by a linear motor, and to prevent thermal deformation of the mechanical parts due to a cooling fluid for cooling a spindle. <P>SOLUTION: This machine tool 1 includes: a base 7; a spindle 4 rotating a member W to be machined; a table 8 for mounting the spindle 4; and a linear motor 14 disposed in the base 7 below the table 8 to push the table 8 in the horizontal direction to the base 7, wherein a cooling fluid supply device for supplying a cooling fluid for cooling the spindle 4 is connected to the spindle 4, a magnetic shield plate 21 made of magnetic material and disposed with a gap 23 between the outer surface of the linear motor 14 and the inner surface of the base 7 to cover the linear motor 14 is provided in the periphery of the linear motor 14, and a passage for circulating the cooling fluid which has cooled the spindle 4 is formed between the linear motor 14 and the magnetic shield plate 21. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a machine tool, and more particularly to a machine tool including a linear motor.

  2. Description of the Related Art Conventionally, various machines including a work stage such as a machine tool or a semiconductor processing apparatus have a structure including a linear motor (see, for example, Patent Document 1). The linear motor propels the work stage linearly with the moving body levitated by the magnetic field generated by the magnet, and since there is no friction, there is no problem of wear of machine parts, and high positioning accuracy Can be maintained continuously.

However, an extremely powerful magnet is used as a magnet for driving the linear motor in order to obtain a large driving force. For this reason, there is a problem that surrounding mechanical parts are magnetized. In particular, in the case of a machine tool, if the machine part is magnetized, the cutting waste of the workpiece is attracted to the machine part, causing problems such as hindering its operation.
As a means for preventing the magnetization of surrounding mechanical parts, a method of obtaining a magnetic shield effect by configuring an outer yoke that surrounds and supports a magnet with a magnetic material has also been proposed (see, for example, Patent Document 2).
JP 2001-218443 A JP 2002-291220 A

  However, in order to obtain a magnetic shielding effect by configuring the outer yoke with a magnetic material, it is necessary to employ a relatively thick outer yoke around the magnet. If the outer yoke is formed thick, it is necessary to secure a large space around the linear motor, and there is a disadvantage that the apparatus becomes large. Further, when the outer yoke becomes a movable part, the weight of the movable part increases, and there is a problem that the control performance is lowered.

  On the other hand, in the case of a machine tool, a spindle that rotates a workpiece or a tool is mounted on a table that is driven by a linear motor. The spindle rotates at a high speed and generates heat. It is necessary to cool the fluid by circulating it around. However, since the cooling fluid after cooling the main shaft is heated by the heat of the main shaft, there may be a disadvantage that the surrounding mechanical parts through which the cooling fluid circulates are thermally deformed. It is necessary to provide sufficient insulation. Even in this case, in order to prevent an increase in the size of the apparatus, it is necessary to configure the heat insulating structure as compactly as possible.

  The present invention has been made in view of the above-described circumstances, and prevents an increase in the size of the apparatus while sufficiently suppressing the magnetization of the surrounding mechanical parts by the linear motor, and also by the cooling fluid that has cooled the main shaft. An object of the present invention is to provide a machine tool capable of preventing thermal deformation of machine parts.

In order to achieve the above object, the present invention provides the following means.
The present invention provides a base, a main shaft for rotating a workpiece or a tool, a table on which the main shaft is mounted, and a linear member that is disposed in a base below the table and that propels the table in a horizontal direction with respect to the base. A cooling fluid supply device connected to the main shaft for supplying a cooling fluid for cooling the main shaft, and a gap is formed around the linear motor between the outer surface of the linear motor and the inner surface of the base. A magnetic shielding plate made of a magnetic material is provided so as to cover the linear motor, and a flow path is formed between the linear motor and the magnetic shielding plate for circulating the cooling fluid that has cooled the main shaft. Provide machine tools.

  According to the present invention, the table on which the main shaft is mounted is propelled in the horizontal direction with respect to the base by the operation of the linear motor. The workpiece is processed with high accuracy by operating the spindle while moving the table and rotating the workpiece or tool. A linear motor uses a powerful magnet to obtain a large driving force, but a magnetic shielding plate made of a magnetic material is disposed around the linear motor with a gap between the outer surface of the linear motor. The presence of the air layer formed therebetween effectively reduces the magnetism that leaks out of the magnetic shielding plate. Furthermore, since a gap is formed between the magnetic shielding plate and the inner surface of the base, the base is prevented from being magnetized by the magnetic force of the linear motor. In this case, the magnetic shielding can be more effectively performed even if the thickness of the combined magnetic shielding plate and the gap is made thinner than in the case of magnetic shielding by the solid outer yoke.

  On the other hand, a cooling fluid is supplied from the cooling fluid supply device to the main shaft, and the main shaft that has generated heat by high-speed rotation is cooled. Since the cooling fluid heated by cooling the main shaft is discharged through the flow path formed by the gap between the magnetic shielding plate and the outer surface of the linear motor, contact with the inner surface of the base is prevented, Thermal deformation of the base can be effectively prevented.

In the above invention, it is preferable that a through hole for guiding the heated cooling fluid discharged from the main shaft to the flow path is provided in the table, and an inner surface of the through hole is covered with a heat insulating material.
According to the present invention, the heated cooling fluid discharged from the main shaft is passed through the through hole formed in the table and guided to the flow path formed between the outer surface of the linear motor and the magnetic shielding plate. However, heat transfer from the cooling fluid to the table is suppressed by the heat insulating material covering the inner surface of the through hole, and thermal deformation of the table can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent effectively that a surrounding mechanical component, especially a base will be magnetized by the magnetism generate | occur | produced from a linear motor. Further, in this case, it is possible to prevent a large space around the linear motor from being occupied by the magnetic shielding. Furthermore, by forming a cooling fluid flow path for cooling the main shaft in the gap between the magnetic shielding plate and the outer surface of the linear motor, it is possible to prevent thermal deformation of the base due to the heated cooling fluid after cooling. In this case, since the gap for magnetic shielding is used as a flow path for the cooling fluid, the space can be used effectively, and the enlargement of the apparatus can be effectively prevented.

Hereinafter, a machine tool according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the machine tool 1 according to the present embodiment includes a stage device 2, a spindle 4 that is mounted on the stage device 2 and includes a chuck 3 that grips a workpiece (workpiece) W, A tool base 6 provided with a tool 5 that is disposed so as to face the main shaft 4 and that processes (cuts or the like) the workpiece W is provided.

The stage device 2 includes a base 7 and a table 8 on which the main shaft 4 is mounted.
The base 7 is provided with an internal space 9 penetratingly formed parallel to the axis of the main shaft 4 at the center thereof, and with a through hole 10 penetrating to the lower surface of the base 7 below the internal space 9.
The table 8 includes a through-hole 11 that penetrates a portion disposed below the main shaft 4 in the vertical direction and communicates the main shaft 4 with the internal space 9 of the base 7. The inner surface of the through hole 11 is covered with a heat insulating material 12.

As shown in FIG. 2, between the base 7 and the table 8, the guide means 13 that supports the table 8 so as to be horizontally movable with respect to the base 7, and the table 8 is pushed in the horizontal direction with respect to the base 7. The linear motor 14 is provided.
As shown in FIG. 2, the guide means 13 supplies the pressurized oil to a plurality of recesses 15 in which the surface facing the base 7 of the table 8 that is arranged with a minute gap with respect to the base 7 is recessed. It is comprised by the several static pressure pad (henceforth the static pressure pad 13) supplied. The supply of pressurized oil will be described later.

  The concave portions 15 constituting the static pressure pad 13 are respectively provided at positions facing each other with the base 7 or the table 8 sandwiched in the horizontal direction and the vertical direction. By supplying oil of a predetermined pressure to these static pressure pads 13 and applying a static pressure to the table 8 in a vertical direction and a horizontal direction for balancing, the table 8 is moved in a vertical direction and a horizontal direction with respect to the base 7. It can be maintained in a state of floating in the direction.

  As shown in FIG. 1, the linear motor 14 includes an internal shaft 18 fixed to the base 7 by a bracket 16 and a nut 17, and a slider (movable member) 19 fixed to the table 8. Yes. The internal shaft 18 has a built-in coil (not shown) that generates a magnetic field around it by a current supplied from the outside, and is provided with a through hole 18a penetrating in the axial direction. The slider 19 is formed in a substantially cylindrical shape, and the inner shaft 18 is arranged in a penetrating state in the central hole 19a. A plurality of annular permanent magnets 20 are arranged on the inner surface of the center hole 19a of the slider 19 along the axial direction. The permanent magnets 20 are arranged with the north and south poles alternately oriented in the opposite direction along the axial direction.

  Therefore, when a current is supplied to the coil of the internal shaft 18 and a magnetic field is formed around the internal shaft 18, the slider 19 is moved with respect to the internal shaft 18 by the action of the magnetic force of the permanent magnet 20 disposed in the magnetic field. It can be propelled in the axial direction. The slider 19 can be positioned at an arbitrary horizontal position with respect to the internal shaft 18 by controlling the current applied to the coil.

  A shield plate (magnetic shield plate) 21 made of an iron plate material is attached to the slider 19 constituting the linear motor 14 so as to cover the side surface and the bottom surface of the slider 19. As shown in FIGS. 2 to 4, the shielding plate 21 is fixed to the slider 19 via a spacing member 22 sandwiched between the slider 19, thereby providing a predetermined gap 23 with the slider 19. It is arranged in the space. The through-hole 11 communicates with the gap 23 between the shielding plate 21 and the slider 19, and the through-hole 24 is provided in the shielding plate 21 that covers the lower surface of the slider 19. A guide cylinder portion 25 extending toward is provided.

Although not shown, the main shaft 4 includes a motor that rotationally drives a shaft that is rotatably supported by a static pressure pad, and an opening / closing mechanism for a chuck 3 that is disposed at the tip of the shaft and is opened and closed to grip the workpiece W. It has.
The tool table 6 also includes a static pressure pad and a linear motor (not shown).

Next, the supply of oil to the machine tool 1 according to the present embodiment will be described.
As shown in FIG. 5, the machine tool 1 according to the present embodiment supplies an oil supply that supplies pressurized oil to the static pressure pads 13, 26, and 27 of the stage device 2, the spindle 4, and the tool base 6. A device 28 is provided. The oil supply device 28 includes an oil tank 29 that stores oil, a motor pump 30 that pressurizes and sends the oil in the oil tank 29, and an oil temperature adjustment device 31 that adjusts the temperature of the oil in the oil tank 29. I have. In the figure, numeral 32 is a strainer, numeral 33 is an oil level gauge, numeral 34 is a filter, numeral 35 is an accumulator, numeral 36 is a pressure gauge, numeral 37 is a pressure switch, and numerals 38 and 39 are oil pans.

By the operation of the oil supply device 28, oil adjusted to a predetermined pressure and temperature is supplied to the static pressure pads 13, 26, 27 via oil supply pipes 40, 41.
The oil supply device 28 is also connected to a through hole 18 a provided in the internal shaft 18 via an oil supply pipe 42. Thereby, the oil adjusted to a predetermined temperature by the oil supply device 28 is circulated through the through hole 18a of the internal shaft 18.
The oil supply device 28 also supplies oil adjusted to a predetermined pressure and temperature to the surroundings of the motor 43 provided on the main shaft 4 and the piston 44 constituting the opening / closing mechanism of the chuck 3 with an oil supply pipe 45. To be supplied through.

  The oil supplied to the static pressure pad 13 of the stage device 2 oozes out from the recess 15 after the table 8 is levitated and flows out into the recovery groove 46 provided in the base 7 or the internal space 9 in the center of the base 7. Then, it is allowed to flow down below the base 7 through the through hole 10. An oil pan 38 is disposed at the bottom of the base 7 so as to collect the oil A flowing down through the through hole 10.

  Further, the oil supplied from one end of the internal shaft 18 of the linear motor 14 of the stage device 2 into the through hole 18 a flows through the through hole 18 a provided in the internal shaft 18 while the coil generated in the internal shaft 18 is generated. The generated heat is cooled and discharged from the other end of the internal shaft 18 in a heated state, and is collected in the oil pan 38 along a path (not shown).

  The oil supplied to the spindle 4 is circulated around the motor 43 to cool the heat generated by the motor 43, or is supplied to the static pressure pad 26 to float the shaft so that the table 8 can be rotated freely. It is caused to flow into the internal space 9 of the base 7 through the provided through hole 11. The through hole 11 of the table 8 communicates with a gap 23 between the linear motor 14 and the shielding plate 21 disposed in the internal space 9 of the base 7. Therefore, as shown in FIG. 6, the oil that has flowed down the through hole 11 of the table 8 is guided to the guide tube portion 25 as indicated by the arrow through the gap 23 between the linear motor 14 and the shielding plate 21, and guided. It is discharged from the cylinder portion 25 toward the oil pan 38 below the base 7.

The oil A collected by the oil pan 38 is returned to the oil tank 29 of the oil supply device 28 for reuse.
Further, the oil supplied to the static pressure pad 27 and the linear motor 47 of the tool base 6 is recovered in an oil pan 39 provided separately in the tool base 6 and then returned to the oil tank 29 of the oil supply device 28. It has become.

The operation of the machine tool 1 according to this embodiment configured as described above will be described below.
In order to machine the workpiece W by the machine tool 1 according to the present embodiment, first, the oil supply device 28 is operated, and the oil adjusted to a predetermined temperature by the oil temperature adjustment device 31 is supplied by the motor pump 30. Pressure is supplied to the stage device 2, the spindle 4 and the tool base 6.

The oil supplied to the stage device 2 is supplied to the static pressure pad 13, thereby supporting the table 8 in a state where it floats with respect to the base 7 in the vertical direction and the horizontal direction. Since the temperature of the oil is adjusted to a predetermined temperature, the table 8 and the base 7 are not thermally deformed by the heat generated by the oil, and the oil is maintained at the predetermined temperature.
The oil supplied to the through hole 18 a of the internal shaft 18 constituting the linear motor 14 cools the internal shaft 18 while being passed through the internal shaft 18.

  The oil supplied to the main shaft 4 is supplied to the static pressure pad 26 to support the shaft in a floating state. Further, the oil is supplied to the periphery of the motor 43, thereby cooling the motor 43 while being circulated around the motor 43. Further, the oil is supplied to the piston 44 constituting the opening / closing mechanism, whereby the chuck 3 is closed and the workpiece W is gripped.

  Further, the oil supplied to the tool base 6 is supplied to the static pressure pad 27 to support the tool 5 in a floating state. Further, the oil supplied to the tool table 6 is supplied to the linear motor 47 so that it is orthogonal to the propulsion direction of the table 8 of the stage device 2 so that the tool 5 is brought close to the workpiece W at a predetermined speed. Promote horizontally.

Next, a current is supplied to the coil of the linear motor 14 to apply a propulsive force to the table 8 in the horizontal direction. In this case, the moving speed of the table 8 and the position of the table 8 can be adjusted by controlling the current supplied to the coil.
Further, a current is supplied to the motor 43 of the spindle 4 to rotate the workpiece W. And the workpiece | work W can be processed by making the tool 5 brought close to contact with the workpiece | work W. FIG.

  In this case, since the coil of the linear motor 14 is arranged in the internal shaft 18, the coil supplied with the current generates heat according to the current value and the resistance value, and heats the internal shaft 18. become. Further, the motor 43 of the spindle 4 also generates heat in order to rotate the workpiece W at a high speed.

According to the stage device 2 of the machine tool 1 according to the present embodiment, since the temperature-controlled oil from the oil supply device 28 is circulated through the through hole 18a formed in the internal shaft 18, it is generated in the coil. The heated heat is cooled by the oil, and the heating of the slider 19 due to the heat generated by the internal shaft 18 and further the heating of the table 8 connected to the slider 19 are prevented. Therefore, the occurrence of thermal deformation in the table 8 is prevented, and a decrease in positioning accuracy of the table 8 can be prevented.
Further, since the temperature-controlled oil from the oil supply device 28 is also circulated around the motor 43 of the main shaft 4, the heat generated by the motor 43 is cooled by the oil.

  In this case, the heated oil after cooling the linear motor 14 is directly discharged from the other end of the internal shaft 18 to the external oil pan 38. Therefore, the disadvantage that the table 8 is heated by the oil heated by cooling the internal shaft 18 can be prevented more reliably.

  On the other hand, the heated oil after cooling the motor 43 of the main shaft 4 enters the internal space 9 of the base 7 through the through holes 11 provided in the table 8 as shown in FIG. 9 is discharged from the guide tube portion 25 to the oil pan 38 through a gap 23 between the shielding plate 21 and the linear motor 14 disposed in the interior 9. Since the heat insulating material 12 is provided on the inner wall surface of the through hole 11 provided in the table 8, the heat of the oil is not transmitted to the table 8, and the oil that has entered the internal space 9 of the base 7 is not transferred. Since the shielding plate 21 prevents contact with the inner wall surface of the base 7, the base 7 is also prevented from being thermally deformed by the heat of the oil.

  Further, in the machine tool 1 according to the present embodiment, the shielding plate 21 provided around the linear motor 14 is made of an iron plate material, and is arranged with a predetermined gap 23 with respect to the outer surface of the linear motor 14. Therefore, the magnetic flux generated by the permanent magnet 20 and the coil of the linear motor 14 is effectively prevented from leaking outside from the shielding plate 21. As a result, it is possible to prevent the mechanical parts arranged around the linear motor 14 such as the base 7 and the table 8 from being magnetized by a strong magnetic force such as the permanent magnet 20 of the linear motor 14.

  In addition, as compared with the conventional method of preventing leakage of magnetic flux by the outer yoke, the shielding structure in the present embodiment having the air layer 23 between the magnetic member called the shielding plate 21 and the slider 19 is thinner. A high shielding effect can be achieved. Therefore, the volume of the internal space 9 formed in the base 7 can be reduced, and the base 7 can be downsized, and the machine tool 1 as a whole can be downsized.

  Further, the cooling of the linear motor 14 is performed by circulating oil through a through hole 18 a provided in the internal shaft 18 fixed to the base 7, so that the oil is supplied from the oil supply device 28 to the through hole 18 a of the internal shaft 18. The oil supply pipe 42 for supplying the oil can be a fixed pipe. As a result, the installation space for the oil supply pipe 42 can be reduced, and the overall size of the machine tool 1 can be reduced.

  In the above embodiment, an iron plate is used as the shielding plate 21, but instead of this, a plate material made of any other magnetic material may be used. Moreover, although the case where the workpiece | work W was attached to the main axis | shaft 4 was demonstrated, it replaced with this and you may decide to attach the tool 5 to the main axis | shaft 4. FIG. Further, the cooling structure applied to the stage device 2 in the above embodiment may be applied to the tool table 6.

It is the front view which fractured | ruptured one part which shows the machine tool which concerns on one Embodiment of this invention. It is the side view which fractured | ruptured one part explaining the structure of the stage apparatus of the machine tool of FIG. It is a partial front view explaining the structure around the linear motor of the stage apparatus of FIG. It is a partial top view of the structure around the linear motor of FIG. It is a circuit diagram explaining the supply system of the oil in the machine tool of FIG. It is an enlarged view explaining the flow of the oil around the linear motor of FIG.

Explanation of symbols

W Workpiece (Workpiece member)
DESCRIPTION OF SYMBOLS 1 Machine tool 4 Spindle 5 Tool 7 Base 8 Table 11 Through-hole 12 Heat insulating material 14 Linear motor 21 Shielding board (magnetic shielding board)
23 Clearance (flow path)
28 Oil supply device (cooling fluid supply device)

Claims (2)

Base and
A spindle that rotates the workpiece or tool;
A table on which the spindle is mounted;
A linear motor disposed in a base below the table and propelling the table in a horizontal direction with respect to the base;
A cooling fluid supply device for supplying a cooling fluid for cooling the main shaft is connected to the main shaft,
Around the linear motor is provided with a magnetic shielding plate made of a magnetic material disposed so as to cover the linear motor with a gap between the outer surface of the linear motor and the inner surface of the base,
A machine tool in which a flow path is formed between the linear motor and the magnetic shielding plate for circulating a cooling fluid that has cooled the main shaft. The table is provided with a through hole that guides the heated cooling fluid discharged from the spindle to the flow path,
The machine tool according to claim 1, wherein an inner surface of the through hole is covered with a heat insulating material.

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