JP5088536B2 - Assembly method of moving coil type linear motor - Google Patents

Description

  The present invention relates to a moving coil type linear motor used as a stage driving unit of a semiconductor manufacturing apparatus, for example.

  In a semiconductor manufacturing facility, as a means for transporting a substrate such as glass to a predetermined position, the X stage that moves in a predetermined direction with respect to the base and the X stage move in another direction (orthogonal direction) with respect to the stage An XY stage apparatus having a Y stage is used. Since a two-axis stage device requires a precise positioning operation and high-speed driving over a long stroke, a multipolar linear DC motor (hereinafter simply referred to as a linear motor) is used as a driving means for each stage. In general, when a responsiveness and high positioning accuracy are required, a moving coil linear motor is used. In this moving coil type linear motor, a permanent magnet having the same magnetization direction is fixed to each of a pair of yokes so that N poles and S poles are alternately arranged along the stroke direction and opposite poles face each other. And a mover having a multi-phase coil disposed in a magnetic gap formed therein.

  Since the stage driving linear motor is required to be small and light, it is conceivable to reduce the size of the magnetic circuit constituting the stator. However, in a magnetic circuit in which only permanent magnets having the same magnetization direction are combined, a large-sized permanent magnet having a complicated shape may be used in order to make the magnetic flux density distribution in the magnetic gap sinusoidal and to increase the magnetic flux density in the magnetic gap. Necessary. Therefore, a magnetic circuit in which a plurality of permanent magnets are arranged along the moving direction while rotating the polarity direction by 90 °, and the volume of the permanent magnet located at the terminal portion is made smaller than the volume of other permanent magnets. A structure has been proposed (see Patent Document 1).

  Also, in a normal magnetic circuit, a yoke that is thicker than necessary is used to prevent saturation of the magnetic flux, so that the weight of the magnetic circuit increases and the yoke is exposed to the outside air. Is likely to occur. Therefore, a structure has been proposed in which a yoke constituting the stator is formed into a U shape by plastic working, and this yoke is housed in a frame made of a U-shaped nonmagnetic material (for example, aluminum) (Patent Document 2). reference).

  Further, in semiconductor manufacturing equipment, a movable coil linear motor that moves a stage on which a substrate is mounted in a predetermined direction (for example, the Y-axis direction) (performs coarse positioning) in order to accurately position the substrate with respect to an exposure apparatus or the like. In addition, a configuration in which an actuator (electromagnet) that moves the stage (object table) by a short distance (performs precise positioning) in a direction orthogonal to the moving direction of the stage (for example, the X-axis direction) has been proposed (Patent Literature). 3). This actuator includes a yoke having an E-shaped cross section connected to the end of the mover in the X-axis direction and a coil disposed on the yoke. By energizing this coil, the actuator is connected to the yoke of the linear motor. The magnetic attraction force is generated.

Japanese Patent Laid-Open No. 11-122905 (pages 3 to 4, FIG. 1) Japanese Unexamined Patent Publication No. 2000-299973 (pages 4-5, FIG. 1) JP 2006-295160 A (pages 11 to 15, page 19, FIGS. 3, 7, 8, and 9)

  However, as described in Patent Document 1, in the case of a so-called Halbach type magnetic circuit, the yoke can be thinned, so that the stator can be reduced in weight somewhat. Is not enough. In addition, as described in Patent Document 2, it is possible to reduce the weight of the stator by housing the magnetic circuit inside the U-shaped frame. However, in order to form the Halbach magnetic circuit in the aluminum frame, Has a problem of requiring a large amount of man-hours. This is because, in the Halbach magnetic circuit, the magnetic poles are arranged so that the magnetic poles of the same polarity are adjacent to each other, so that it is extremely difficult to fix all the permanent magnets to the yoke due to the magnetic repulsive force.

  Furthermore, in the structure described in Patent Document 3, since an electromagnet (yoke and coil) is added to the mover, it is predicted that the weight of the mover increases and the motor efficiency decreases.

  Accordingly, an object of the present invention is to provide a moving coil type linear motor that is easy to assemble a stator and is small and light.

In order to achieve the above object, a moving coil linear motor of the present invention includes a stator having a first magnetic air gap in which a sinusoidal magnetic flux density distribution appears along a predetermined direction, and the first magnetic air gap. In a moving coil type linear motor having a mover including a multiphase coil arranged in
The stator includes a first permanent magnet member in which permanent magnets having different magnetization directions are alternately arranged along a moving direction of the mover on a yoke made of a ferromagnetic material to form the first magnetic gap; A second permanent magnet member in which a permanent magnet is fixed so that a magnetic pole of a different polarity is opposed to a yoke made of a ferromagnetic material via a second magnetic air gap; the first permanent magnet member; and the second permanent magnet member While having a plurality of divided units having a non-magnetic frame that encloses a permanent magnet member and has a specific gravity smaller than that of the yoke,
The mover includes a single-phase coil disposed in the second magnetic gap, and is supported so as to be movable in a direction orthogonal to the moving direction.

  In the present invention, the nonmagnetic frame includes a base member that supports the second permanent magnet member and side members that are fixed to both side surfaces of the base member and support the first permanent magnet member. The nonmagnetic frame is preferably made of aluminum or an alloy thereof.

  In the present invention, the permanent magnet includes R (R is one or more elements selected from rare earth elements such as Nd), T (T is Fe or Fe and Co), and B. It is preferably made of an RTB-based sintered magnet as an essential component.

  According to the present invention, the stator has first permanent magnet members formed by alternately arranging yokes made of a ferromagnetic material and permanent magnets having different magnetization directions along the moving direction of the mover. Can be made thinner. In addition, since the first permanent magnet member and the second permanent magnet member for moving the mover in the direction perpendicular to the moving direction are held by a nonmagnetic frame made of a metal material having a specific gravity smaller than that of the yoke, A reduction in size and weight of the stator can be achieved.

  In addition, since the single-phase coil attached to the mover is interposed in the second magnetic gap, the mover is slightly increased in the direction perpendicular to the moving direction (for example, several mm) by slightly increasing the weight of the mover. ) And the position of the mover can be finely adjusted.

  Further, the non-magnetic frame is formed by a base member that supports the second permanent magnet member and side members that are fixed to both side surfaces and support the first permanent magnet member, thereby assembling the Halbach-type magnetic circuit. Can be easily performed.

  Details of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a side view of an XY stage provided with a linear motor according to an embodiment of the present invention, FIG. 2 is an arrow view of FIG. 1 viewed from the direction A, and FIG. 3 is a cross-sectional view taken along line BB in FIG. 4-8 is a figure for demonstrating the assembly method of a stator. For ease of understanding, the movable table, the arm, and the second magnetic circuit member are omitted in FIG.

The XY stage shown in FIG. 1 includes a stator 2 installed at both ends in the X-axis direction of a stage (not shown), and a mover 11 that moves along the Y-axis direction (direction perpendicular to the paper surface). A moving table 100 driven by the linear motor 1 is provided. The moving table 100 is connected to the mover 11 via arms 102 fixed at both ends thereof.

As shown in FIGS. 2 and 3 , the linear motor 1 includes a stator 2 in which a plurality of divided units 3a, 3b, and 3c are connected in the Y-axis direction, and a first magnetic gap g1 formed therein. Is provided with a mover 11 that moves along the Y-axis direction. The mover 11 has a coil unit 121 fixed to the holder 111. The coil unit 121 has a multiphase coil (for example, a three-phase coil) 122 in which a plurality of flat coils are arranged along the Y-axis direction and a single phase that extends along the Y-axis direction (for example, is formed in an oval shape). A coil ( air core coil ) 123 is provided. Each flat coil is connected so that a thrust in the Y-axis direction is generated when the coil of each phase is energized. Since the coil unit 121 allows a large current to flow through the multiphase coil, the multiphase coil portion is formed to be thicker than the single phase coil portion in order to reduce heat generation (to prevent deterioration of motor performance and positioning accuracy). It is preferable to provide a passage through which the refrigerant flows. In FIG. 3 , although two air-core coils (single-phase coils) are provided, the number of coils may be set according to the required thrust, and when a large thrust is not required, a single air-core coil is used. (Single phase coil) may be used.

  According to this linear motor 1, by detecting the magnetic pole position of the permanent magnet constituting the stator by a magnetic field detection element (for example, Hall element) provided on the mover, and changing the direction of the current flowing through each flat coil, The mover 11 can be moved in the Y direction. Further, after moving the mover to a predetermined position in the Y-axis direction, the single-phase coil 123 is energized at that position, and the direction of the current is switched to move the mover 11 in the X direction by a minute distance (for example, several mm). It can be moved (in the case of FIG. 3, it can be moved up and down).

  The structure of the stator 2 which is the most characteristic part of the present invention will be described with reference to FIGS. As described above, the stator 2 is formed by connecting a plurality of (for example, three) divided units 3a, 3b, and 3c along the Y-axis direction (see FIG. 2). After being assembled in the state shown in FIG. 3, the stator 2 is installed on a stage (not shown) so as to be in the posture shown in FIG. Since each divided unit has the same structure (however, the lengths need not be the same), the divided unit 3a will be described, and the description of the other divided units will be omitted.

The division unit 3a includes a U-shaped nonmagnetic frame 4 made of a nonmagnetic material having a specific gravity smaller than that of a steel material, first permanent magnet members 5a, 5b, 5c and a second permanent magnet provided on the inside thereof. A member 8 is provided. The first permanent magnet member 5a (5b, 5c) has a thickness direction on one surface of a yoke 6a (6b, 6c) formed in a flat plate shape made of a ferromagnetic material such as a steel material (for example, SS material). It is formed by alternately disposing the main magnet 7a magnetized in the direction orthogonal to the X-axis direction and the Y-axis direction and the spacer magnet 70a magnetized in the direction orthogonal to the magnetization direction (Y-axis direction). ing. The main magnet 7a has N and S poles alternately arranged along the X-axis direction, and the spacer magnet 70a is arranged so that the same polarity magnetic poles face each other across the main magnet 7a. Further, the main magnets 7a facing each other across the first magnetic gap g1 are arranged so that the magnetic poles of different polarities face each other.

  Since the first permanent magnet member 5a (5b, 5c) forms a so-called Halbach magnetic circuit, even if the thickness of the yoke is less than half that of the permanent magnet, the first magnetic member 5a (5b, 5c) A high magnetic flux density (for example, 0.8 to 0.9 T) can be obtained in the gap g1, and the thrust can be increased. According to this magnetic circuit, even if a simple rectangular permanent magnet is used, a magnetic flux density distribution that approximates a sine wave can be obtained in the first magnetic gap g1. In each divided unit, the length of the permanent magnet on one end side may be shorter than that of the other permanent magnets, thereby bringing the magnetic flux density distribution (Y-axis direction) in the first magnetic gap g1 closer to a sine wave. be able to.

  The second permanent magnet member 8 is made of a ferromagnetic material such as a steel material (for example, SS material), and is magnetized in the thickness direction on one surface of a yoke 9 formed in a flat plate shape extending in the Y-axis direction. It is formed by fixing a plurality of permanent magnets 10a, 10b having different magnetization directions along the X-axis direction. These permanent magnets 10a and 10b are arranged so that the magnetic poles having the polarities shown in the figure appear on the second magnetic gap g2 side (the pair of permanent magnet members 8 facing each other across the second magnetic gap g2 Arranged so that the magnetic poles face each other). The second permanent magnet member 8 is provided over the entire length (the length in the Y-axis direction) of the divided unit 3a.

  The nonmagnetic frame 4 has a prismatic base member 41 and flat side members 42 fixed to both sides thereof. The base member 41 is formed on the lower end side of the first step portion 411 with which a part of the lower end surface of the permanent magnet member 5a (yoke 6a) abuts, the concave portion 412 in which the lower portion of the coil unit 121 is interposed. In addition, the yoke 9 has a second step portion 413 against which the lower end surface of the yoke 9 abuts.

  The procedure for assembling the above-described divided unit 3a (the same applies to 3b and 3c) will be described with reference to FIGS. First, the second magnetic gap g <b> 2 is formed inside the base member 41 by fixing the second permanent magnet member 8 to the inner surface of the recess 412 of the base member 41. Next, the side members 42 are fixed to both side surfaces of the base member 41 (see FIG. 4).

Also, as shown in FIG. 5, a pair of members are prepared in which the main magnet 7a is fixed to the yoke 6a with a predetermined interval (as much as the length of the spacer magnet 70a ), and a nonmagnetic material (for example, plastic) is provided between them. By opposing the magnetic poles of different polarities across the flat spacer 50 (thickness ts) made of the two members, both members are magnetically attracted and integrated (a). Next, by inserting the spacer magnet 70a between the main magnets 7a, the first permanent magnet member with spacer (thickness t2) in which the spacer 50 is sandwiched between the two members is produced (b).

In the next step, as shown in FIG. 6, the first permanent magnet member 5a with a spacer is lowered in the direction of the outlined arrow. In this case, by previously larger than the thickness t2 of the first permanent magnet member 5a with spacers inner dimension t1 between the pair of side members 42, the yoke 6a of the first permanent magnet member 5a is attached spacer The base member 41 is placed on the first step 411.

In this state, a bolt (none of which is not shown) is screwed into a female screw provided in the yoke 6a from a drill hole 422 provided at a position indicated by a one-dot chain line of the side member 42, and the first permanent magnet member 5a is illustrated as white. By displacing in the direction of the arrow, the interval t3 between the permanent magnets increases, and the spacer 50 falls on the second permanent magnet member 8 (see FIG. 7). Therefore, the first permanent magnet member 5a having the first magnetic gap g1 can be assembled by pulling out the spacer 50 in the direction perpendicular to the paper surface (Y-axis direction).

The divided unit 3a can be assembled by fixing all the first permanent magnet members 5a to 5c to the nonmagnetic frame 4 in the same procedure as described above. As shown in FIG. 8, the side member 42 is used for extracting, for example, two rows of drill holes 421 into which bolts (not shown) for fixing them to the base member are inserted, and the above spacer from between the permanent magnet members. And two rows of drill holes 422 into which bolts (not shown) are inserted. Stator 1 is completed by connecting division unit 3a , 3b , 3c assembled in this way in series.

  According to the above stator, the first permanent magnet members 5a, 5b, 5c and the second permanent magnet member 8 are held by the nonmagnetic frame which is lighter than the constituent members (yoke and permanent magnet). The stator can be made smaller and lighter than a simple stator and permanent magnet. In particular, since the nonmagnetic frame is formed by the base member and the side members fixed to the both side surfaces thereof, the Halbach type magnetic circuit is obtained by drawing the first permanent magnet member into the nonmagnetic frame and pulling it toward the side member side. It is possible to fix the first permanent magnet member constituting the predetermined position at a predetermined position without much man-hours, and the stator can be easily assembled.

  Each permanent magnet member can be made of permanent magnets having the same dimensions, and a magnetic circuit member having the same cross-sectional shape can be connected to reduce the number of steps for manufacturing the stator. Although the length of the permanent magnet member is set according to the moving distance of the mover, the length may be adjusted by changing the length of the permanent magnets or the number of permanent magnets used.

  In the present invention, the nonmagnetic frame may be formed of a material having a specific gravity smaller than that of the yoke material (for example, carbon steel, specific gravity is 7.85). However, from a practical standpoint (cost, rigidity, etc.), an aluminum alloy (specific gravity) It is preferable to form in 2.8). However, other nonmagnetic metal materials (for example, Mg alloy: specific gravity is about 2/3 that of aluminum alloy) can be used, and plastic materials (for example, FRP) and ceramic materials (for example, zirconia: specific gravity is 3.8). ).

  In the present invention, the permanent magnet can be formed of a known permanent magnet, for example, a rare earth magnet, and in particular, R (R is one or more elements selected from rare earth elements such as Nd. ), T (T is Fe or Fe and Co.) and R-T-B based sintered magnets containing B as essential components are suitable.

It is a side view of the XY stage provided with the linear motor concerning embodiment of this invention. It is the arrow view which looked at FIG. 1 from the A direction. FIG. 3 is a sectional view taken along line B-B in FIG. 2. It is a figure which shows the state in the middle of the assembly of a division | segmentation unit (The state which fixes a side member to the base member which fixed the 2nd magnet member is shown). The assembled intermediate states of the divided units is shown to view (showing a state of assembling the first permanent magnet member with a spacer). The assembled intermediate states of the divided units is shown to view (a state of inserting the first permanent magnet member with a spacer in a non-magnetic frame). The assembly at the end of the state of the divided units are shown to FIG. It is the arrow line view which looked at FIG. 7 from the C direction.

Explanation of symbols

1: linear motor, 2: stator, 3a, 3b, 3c: divided unit,
4: non-magnetic frame, 41: base member, 411: first step, 412: concave groove, 413: second step, 42: side member, 421, 422: drill hole,
5a, 5b, 5c: first permanent magnet member, 6a, 6b, 6c: yoke,
7a: main magnet, 70a : spacer magnet,
8: second permanent magnet member, 9: yoke, 10a, 10b: permanent magnet,
11: Movable element, 111: Coil holder, 121: Coil unit, 122: Multi-phase coil, 123: Single-phase coil (air-core coil) ,
100: Moving table, 102: Arm

Claims (2)

A stator having a second magnetic air gap together with a first magnetic air gap in which a sinusoidal magnetic flux density distribution appears along a predetermined direction, and the second phase together with a multiphase coil disposed in the first magnetic air gap A single-phase coil disposed in the magnetic gap, supported by the energization of the multi-phase coil so as to be movable along the longitudinal direction of the stator, and the longitudinal direction of the stator by energization of the single-phase coil; have a movable element that is movably supported along a direction perpendicular to the direction,
The stator is magnetized in a direction orthogonal to the moving direction of the mover along the moving direction of the mover by energizing the multiphase coil on each facing surface side of the pair of first yokes made of a ferromagnetic material. It was the main magnet and the first permanent magnet member that the spacer magnet magnetized in a direction orthogonal to the magnetization direction are arranged alternately forming the first magnetic gap, a second pair of ferromagnetic material A permanent magnet is disposed on each opposing surface side of the yoke so that magnetic poles of different polarities appear along the moving direction of the mover by energizing the single-phase coil, and magnetic poles of different polarities face each other. a second permanent magnet member forming a second magnetic gap, Ri Do from the small consisting metal material having a specific gravity from the yoke, both sides of the base member and the base member having a recess for supporting the second permanent magnet member The first permanent fixed to the surface Moving a plurality of divided units having a non-magnetic frame by a pair of side members for supporting the stone member that Soo packaging said first and second permanent magnet members of the movable element by energization of the polyphase coil A method of assembling a moving coil type linear motor connected along a direction,
Fixing the second permanent magnet member to the inner surface of the concave portion of the base member;
Fixing side members on both side surfaces of the base member;
A predetermined interval is provided along the moving direction of the mover by energization of the multiphase coil on the side of the pair of first yokes facing the first magnetic gap, and the first yoke is interposed through the first magnetic gap. The main magnets arranged such that the magnetic poles facing each other have different polarities, and magnetically attracting and integrating the non-magnetic spacer,
A step of forming the first permanent magnet member with a non-magnetic spacer by inserting the spacer magnet into the predetermined interval of the main magnet integrated magnetically by sandwiching the non-magnetic spacer; and
Inserting the first permanent magnet member with a non-magnetic spacer between the pair of side members and placing it on the base member;
A bolt is screwed into a female thread portion provided in each of the pair of first yokes from a hole provided in each of the pair of side members, and the nonmagnetic spacer is attached via each of the pair of first yokes. The first permanent magnet member is displaced toward each of the pair of side members, and the interval between the main magnets and the spacer magnets facing each other via the nonmagnetic spacer is increased, thereby providing the nonmagnetic spacer. Removing the non-magnetic spacer from the first permanent magnet member and making the removed portion the first magnetic gap;
A method of assembling the moving coil linear motor , comprising the step of assembling the divided unit . 2. The method of assembling a moving coil linear motor according to claim 1, wherein the nonmagnetic frame is made of aluminum or an alloy thereof.

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