Linear motor and method for adjusting position of coil of linear motor

Abstract

This linear motor comprises: a stator; and a mover. The stator includes a magnet rail having a first surface and a second surface positioned on a side opposite from the first surface. The mover includes: a base that moves in a first direction with respect to the magnet rail; a first coil that is attached to the base by means of a first position adjustment mechanism and that faces the first surface; a first cooler that is fixed to the surface of the first coil on a side opposite from the magnet rail; a second coil that is attached to the base by means of a second position adjustment mechanism and that faces the second surface; and a second cooler fixed to the surface of the second coil on a side opposite from the magnet rail.

Description

Linear motor and method for adjusting coil position of linear motor

[0001] The technology disclosed in this specification relates to a linear motor.

[0002] The linear motor disclosed in Japanese Patent Publication No. 2015-119531 (hereinafter referred to as Patent Document 1) has a stator and a mover. The stator has a magnet rail. A plurality of magnets are arranged on both surfaces of the magnet rail. The mover has a base that moves along the magnet rail and two coils (hereinafter referred to as the first coil and the second coil) attached to the base. The first coil faces one surface of the magnet rail, and the second coil faces the other surface of the magnet rail. The mover moves along the magnet rail by controlling the current in each coil.

[0003] In the linear motor of Patent Document 1, each coil can be moved relative to the base. This allows the distance between each coil and the magnet rail to be adjusted. By adjusting the distance between each coil and the magnet rail, the thrust of the linear motor can be adjusted to an appropriate value.

[0004] A cooler for cooling the coils may be provided on the mover. When each coil is moved relative to the base as in Patent Document 1, the cooling efficiency for each coil changes, and each coil may not be cooled efficiently. This specification proposes a technology for appropriately cooling each coil in a linear motor in which each coil can be moved relative to the base.

[0005] The linear motor disclosed in this specification includes a stator and a mover. The stator includes a magnet rail having a first surface on which a plurality of magnets are arranged along a first direction and a second surface opposite the first surface on which a plurality of magnets are arranged along the first direction. The mover includes a base that moves along the first direction relative to the magnet rail, a first position adjustment mechanism, a first coil attached to the base via the first position adjustment mechanism and facing the first surface, a first cooler fixed to the surface of the first coil opposite the magnet rail, a second position adjustment mechanism, a second coil attached to the base via the second position adjustment mechanism and facing the second surface, and a second cooler fixed to the surface of the second coil opposite the magnet rail. The first position adjustment mechanism adjusts the position of the first coil relative to the base in a second direction from the first coil to the second coil. The second position adjustment mechanism adjusts the position of the second coil relative to the base in the second direction.

[0006] In this linear motor, the position of the first coil can be adjusted by the first position adjustment mechanism, and the position of the second coil can be adjusted by the second position adjustment mechanism. Furthermore, because the first cooler is fixed to the surface of the first coil, the relative positions of the first coil and the first cooler do not change even when the first coil is moved by the first position adjustment mechanism. Furthermore, because the second cooler is fixed to the surface of the second coil, the relative positions of the second coil and the second cooler do not change even when the second coil is moved by the second position adjustment mechanism. Therefore, each coil can be appropriately cooled.

[0007] 1 is a perspective view of a component mounter 10. FIG. 2 is a top view of the component mounter 10. FIG. 3 is a perspective view of an X-axis linear motor 30. FIG. 4 is a side view of the X-axis linear motor 30. FIG. 5 is a plan view of a mover 50 with a head 20 removed.

[0008] The mounter 10 of the embodiment shown in Figures 1 and 2 picks up components supplied from a feeder F and mounts them on a board S. The mounter 10 includes a base 12, a board transport device (not shown), component mounting heads 20a and 20b, X-axis linear motors 30a and 30b, and a Y-axis linear motor 24. These are housed in a housing 11. An operation panel 14 is installed on the front of the housing 11 and is operable by an operator and capable of displaying various information. Note that, hereinafter, the axis extending horizontally in the left-right direction of the mounter 10 is referred to as the X-axis, and the axis extending horizontally in the front-rear direction of the mounter 10 is referred to as the Y-axis.

[0009] The substrate transport device includes a conveyor belt and a motor that drives the conveyor belt in a circular motion. The substrate transport device drives the conveyor belt with the motor to transport the substrate S on the conveyor belt from left to right.

[0010] On both the left and right sides of the upper stage of the base 12, band-shaped support bases 13 extending in the front-to-rear direction are provided. Stators 25 of Y-axis linear motors 24 are provided on each support base 13. Movers 26a, 26b are provided on each stator 25. Movers 26a, 26b are movable back and forth along the Y axis. X-axis linear motor 30a has beam member 21a. X-axis linear motor 30b has beam member 21b. Beam members 21a, 21b are elongated members extending in the left-to-right direction and arranged parallel to each other. Beam member 21a spans from left mover 26a to right mover 26a. Beam member 21b spans from left mover 26b to right mover 26b. Y-axis linear motor 24 moves X-axis linear motors 30a, 30b back and forth along the Y axis.

[0011] The X-axis linear motor 30a moves the head 20a left and right along the X-axis. The X-axis linear motor 30a and the Y-axis linear motor 24 are driven to move the head 20a in the X-axis and Y-axis directions. The X-axis linear motor 30b moves the head 20b left and right along the X-axis. The X-axis linear motor 30b and the Y-axis linear motor 24 are driven to move the head 20b in the X-axis and Y-axis directions. The heads 20a and 20b have nozzles that pick up components. The heads 20a and 20b pick up components supplied from the feeder F and mount the picked-up components on the board S.

[0012] Next, we will explain the structure of the X-axis linear motor 30. Since the X-axis linear motors 30a and 30b have the same structure, we will explain only the X-axis linear motor 30b below. As shown in Figures 3 and 4, the X-axis linear motor 30b has a stator 40 and a mover 50 that moves relative to the stator 40.

[0013] The stator 40 has a beam member 21, guide rails 42a and 42b, and a magnet rail 44. As shown in Fig. 3, the beam member 21 is a rectangular cylindrical member that extends along the X-axis. The beam member 21 is made of carbon fiber reinforced plastic (CFRP) or aramid fiber reinforced plastic (AFRP).

[0014] Two ridges 41a and 41b protruding from the side surface 21s of the beam member 21 are provided on the side surface 21s. The ridges 41a and 41b extend linearly parallel to the X-axis. The ridge 41b is spaced apart from the ridge 41a and is disposed below the ridge 41a. A guide rail 42a is provided at the tip of the ridge 41a, and a guide rail 42b is provided at the tip of the ridge 41b. The guide rails 42a and 42b extend linearly parallel to the X-axis.

[0015] A magnet rail 44 is provided on the side surface 21s of the beam member 21. The magnet rail 44 is arranged between the protrusions 41a and 41b in the vertical direction. The magnet rail 44 has a yoke 44a and multiple magnets 44b (i.e., permanent magnets). The yoke 44a is made of a high-permeability material. The yoke 44a protrudes from the side surface 21s and extends linearly parallel to the X-axis. The yoke 44a has a base portion 44a-1 and a plate portion 44a-2 that is narrower than the base portion 44a-1. The base portion 44a-1 is a portion fixed to the side surface 21s and extends parallel to the X-axis. The plate portion 44a-2 is a plate-shaped portion protruding forward from the base portion 44a-1. The plate portion 44a-2 extends parallel to the X-axis. Multiple magnets 44b are fixed to the upper and lower surfaces of the plate portion 44a-2. Each magnet 44b is fixed so that the direction of its magnetic field is in the vertical direction. The multiple magnets 44b-1 fixed to the upper surface of the plate portion 44a-2 are arranged along the X-axis. The multiple magnets 44b-1 are arranged so that their polarities alternate. The multiple magnets 44b-2 fixed to the lower surface of the plate portion 44a-2 are arranged along the X-axis. The multiple magnets 44b-2 are arranged so that their polarities alternate. Hereinafter, the surface (i.e., the upper surface) of the magnet rail 44 formed by the multiple magnets 44b-1 will be referred to as the first surface 45a, and the surface (i.e., the lower surface) of the magnet rail 44 formed by the multiple magnets 44b-2 will be referred to as the second surface 45b.

[0016] The mover 50 has a base 58, a first coil 51a, a second coil 51b, a first cooler 52a, a second cooler 52b, a first position adjustment mechanism 53a, a second position adjustment mechanism 53b, carriages 54a, 54b, and a head 20.

[0017] The carriage 54a is engaged with the guide rail 42a. The carriage 54a is movable along the guide rail 42a. The carriage 54b is engaged with the guide rail 42b. The carriage 54b is movable along the guide rail 42b. The carriage 54b is disposed below the carriage 54a with a gap therebetween. The base 58 spans from the carriage 54a to the carriage 54b. Therefore, the base 58 is movable in the X-axis direction along the guide rails 42a and 42b. The carriages 54a and 54b are fixed to an inner surface 58b of the base 58 (i.e., the surface on the magnet rail 44 side).

[0018] The head 20 is fixed to an outer surface 58a of the base 58 (i.e., the surface opposite to the magnet rail 44). The head 20 is detachable from the base 58.

[0019] A first coil 51a and a second coil 51b are attached to an inner surface 58b of the base 58. The first coil 51a and the second coil 51b are formed by conductive wires wound around cores. Note that a plurality of first coils 51a and a plurality of second coils 51b may be provided on the mover 50. The first coil 51a is attached to the surface 58b via a first position adjustment mechanism 53a. The second coil 51b is attached to the surface 58b via a second position adjustment mechanism 53b.

[0020] The base 58 has an opening 58c. The opening 58c is configured as a hole that penetrates the base 58 from the surface 58a to the surface 58b. The opening 58c is provided in approximately the center of the base 58. When the head 20 is attached to the surface 58a of the base 58, the opening 58c is closed by the head 20. As shown in FIG. 5 , when the head 20 is removed from the surface 58a of the base 58, the surfaces of the first position adjustment mechanism 53a and the second position adjustment mechanism 53b are exposed within the opening 58c.

[0021] As shown in FIG. 4 , the first coil 51a is disposed opposite the first surface 45a of the magnet rail 44 (i.e., above the magnet rail 44). A gap 60 is provided between the first coil 51a and the first surface 45a. The first position adjustment mechanism 53a connects the first coil 51a to the base 58. The first position adjustment mechanism 53a has a function of changing the mounting position of the first coil 51a relative to the base 58 in the vertical direction. The first position adjustment mechanism 53a may be any mechanism capable of moving the first coil 51a up and down relative to the base 58. For example, the first position adjustment mechanism 53a may be a mechanism (e.g., a serribolt) that moves the first coil 51a up and down using a position adjustment screw, or may be a mechanism that uses a vertically elongated slot as a mounting hole. In this embodiment, the first position adjustment mechanism 53a has a first operating unit 55a. The first operating unit 55a is a member that is operated by a tool or the like (e.g., a screwdriver). When the user rotates the first operating unit 55a, the first position adjustment mechanism 53a moves the first coil 51a up and down, thereby changing the width W60 of the gap 60. The first operating unit 55a is disposed within the opening 58c.

[0022] A first cooler 52a that cools the first coil 51a is fixed to the first coil 51a. The first cooler 52a is fixed to the surface of the first coil 51a that is located opposite the magnet rail 44 (i.e., the upper surface). The first cooler 52a may cool the first coil 51a, for example, by heat exchange with air. Because the first cooler 52a is fixed to the surface of the first coil 51a, when the first coil 51a is moved by the first position adjustment mechanism 53a, the first cooler 52a moves together with the first coil 51a, and the relative positions of the first cooler 52a and the first coil 51a do not change. Therefore, the first coil 51a can be efficiently cooled by the first cooler 52a regardless of the position of the first coil 51a.

[0023] The second coil 51b is disposed in a position facing the second surface 45b of the magnet rail 44 (i.e., below the magnet rail 44). A gap 62 is provided between the second coil 51b and the second surface 45b. The second position adjustment mechanism 53b connects the second coil 51b to the base 58. The second position adjustment mechanism 53b has a function of changing the mounting position of the second coil 51b relative to the base 58 in the vertical direction. The second position adjustment mechanism 53b may be any mechanism capable of moving the second coil 51b up and down relative to the base 58. For example, the second position adjustment mechanism 53b may be a mechanism (e.g., a serivolt) that moves the second coil 51b up and down using a position adjustment screw, or may be a mechanism that uses a vertically elongated slot as a mounting hole. In this embodiment, the second position adjustment mechanism 53b has a second operating unit 55b. The second operating unit 55b is a member that is operated by a tool or the like. When the user rotates the second operating unit 55b, the second position adjustment mechanism 53b moves the second coil 51b up and down, thereby changing the width W62 of the gap 62. The second operating unit 55b is disposed within the opening 58c.

[0024] A second cooler 52b that cools the second coil 51b is fixed to the second coil 51b. The second cooler 52b is fixed to the surface of the second coil 51b that is located opposite the magnet rail 44 (i.e., the bottom surface). The second cooler 52b may cool the second coil 51b by, for example, exchanging heat with air. Because the second cooler 52b is fixed to the surface of the second coil 51b, when the second coil 51b is moved by the second position adjustment mechanism 53b, the second cooler 52b moves with the second coil 51b, and the relative positions of the second cooler 52b and the second coil 51b do not change. Therefore, the second coil 51b can be efficiently cooled by the second cooler 52b regardless of the position of the second coil 51b.

[0025] 5, when the head 20 is removed from the surface 58a of the base 58, the first operating portion 55a and the second operating portion 55b are exposed in the opening 58c. Therefore, the user can access the first operating portion 55a and the second operating portion 55b from the opening 58c and adjust the widths W60 and W62 of the gaps 60 and 62.

[0026] As shown in FIG. 4, the first position adjustment mechanism 53a and the second position adjustment mechanism 53b are disposed between the carriages 54a and 54b in the vertical direction. By disposing the carriages 54a and 54b in this manner, the distance between the carriages 54a and 54b is increased, stabilizing the base 58. Furthermore, with this arrangement, the second operation unit 55b can be provided near the first operation unit 55a. Therefore, the first operation unit 55a and the second operation unit 55b are easy to operate.

[0027] A current can be passed through the first coil 51 a and the second coil 51 b via a cable (not shown). When a current flows through the first coil 51 a, a magnetic force acts between the first coil 51 a and the magnet rail 44. When a current flows through the second coil 51 b, a magnetic force acts between the second coil 51 b and the magnet rail 44. By controlling the current flowing through the first coil 51 a and the second coil 51 b, the mover 50 can be moved in the X direction relative to the stator 40.

[0028] Next, the coil position adjustment process will be described. The width W60 of the gap 60 between the first coil 51a and the magnet rail 44 affects the magnetic force acting on the first coil 51a. The width W62 of the gap 62 between the second coil 51b and the magnet rail 44 affects the magnetic force acting on the second coil 51b. Therefore, if the widths W60 and W62 are not appropriate, the X-axis linear motor 30 will not provide the appropriate thrust. Furthermore, if the widths W60 and W62 are not equal, the magnetic forces acting on the first coil 51a and the second coil 51b will be unbalanced, resulting in cogging. In the position adjustment process, these problems are suppressed by adjusting the widths W60 and W62.

[0029] The position adjustment process is performed after the mounter 10 is assembled and before shipping. Therefore, as shown in FIG. 3 , the position adjustment process is performed in a state in which the magnet rail 44 is arranged with the first surface 45a facing upward, the first coil 51a is arranged above the magnet rail 44, and the second coil 51b is arranged below the magnet rail 44. In the position adjustment process, the head 20 is removed from the base 58, and the first operating unit 55a and the second operating unit 55b are operated. The position of the first coil 51a (i.e., width W60) is adjusted by the first position adjustment mechanism 53a, and the position of the second coil 51b (i.e., width W62) is adjusted by the second position adjustment mechanism 53b.

[0030] In the position adjustment process, the widths W60 and W62 can be adjusted so that an appropriate thrust force is obtained in the X-axis linear motor 30. Furthermore, in this embodiment, the first position adjustment mechanism 53a and the second position adjustment mechanism 53b are independent. That is, the amount of position adjustment of the first coil 51a by the first position adjustment mechanism 53a and the amount of position adjustment of the second coil 51b by the second position adjustment mechanism 53b are independent of each other. Therefore, the widths W60 and W62 can be adjusted independently, and imbalance between the widths W60 and W62 can be prevented. This reduces cogging.

[0031] The widths W60 and W62 vary depending on the orientation in which the X-axis linear motor 30 is installed. For example, the direction of gravity acting on the mover 50 when the X-axis linear motor 30 is installed horizontally (i.e., with the magnet rail 44 oriented horizontally) as shown in FIG. 3 differs from the direction of gravity acting on the mover 50 when the X-axis linear motor 30 is installed vertically (i.e., with the magnet rail 44 oriented vertically). Therefore, even if the widths W60 and W62 are adjusted with the X-axis linear motor 30 oriented vertically, if the X-axis linear motor 30 is then installed horizontally as shown in FIG. 3, the widths W60 and W62 may deviate from the appropriate values. In contrast, in the position adjustment process described above, the widths W60 and W62 are adjusted with the X-axis linear motor 30 positioned similarly to the actual usage situation as shown in FIG. 3, preventing deviations in the widths W60 and W62.

[0032] Furthermore, in this embodiment, the yoke 44a of the magnet rail 44 has a wide base 44a-1, which makes it difficult for the magnet rail 44 to bend. This makes it possible to reduce errors in the widths W60 and W62.

[0033] In this embodiment, the first operating unit 55a and the second operating unit 55b are covered by the head 20. By removing the head 20 from the base 58, the first operating unit 55a and the second operating unit 55b can be operated. With this configuration, the head 20 can be arranged so as to overlap the first operating unit 55a and the second operating unit 55b, thereby reducing the size of the mover 50. Furthermore, with this configuration, the first operating unit 55a and the second operating unit 55b can be operated without interfering with the stator 40 using a tool.

[0034] The left-right direction in the embodiment is an example of a first direction. The up-down direction in the embodiment is an example of a second direction. The beam member in the embodiment is an example of a support member.

[0035] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of these objectives itself has technical utility.

Claims

1. A linear motor having a stator and a mover, wherein the stator has a magnet rail having a first surface on which a plurality of magnets are arranged along a first direction, and a second surface opposite the first surface and on which a plurality of magnets are arranged along the first direction, and the mover has: a base that moves along the first direction relative to the magnet rail; a first position adjustment mechanism; a first coil attached to the base via the first position adjustment mechanism and facing the first surface; a first cooler fixed to the surface of the first coil opposite the magnet rail; a second position adjustment mechanism; a second coil attached to the base via the second position adjustment mechanism and facing the second surface; and a second cooler fixed to the surface of the second coil opposite the magnet rail, wherein the first position adjustment mechanism adjusts the position of the first coil with respect to the base in a second direction from the first coil to the second coil, and the second position adjustment mechanism adjusts the position of the second coil with respect to the base in the second direction.

2. A linear motor as described in claim 1, wherein the stator has: a first guide rail extending along the first direction; and a second guide rail extending along the first direction, the second guide rail being arranged so that the magnet rail is positioned between the first guide rail and the second guide rail in the second direction; the mover has: a first carriage attached to the base and sliding along the first guide rail; and a second carriage attached to the base and sliding along the second guide rail; and the first position adjustment mechanism and the second position adjustment mechanism are disposed between the first carriage and the second carriage in the second direction.

3. A linear motor as described in claim 1 or 2, wherein the stator further has a support member, and the magnet rail has a yoke base fixed to the support member and extending along the first direction, and a yoke plate portion narrower than the yoke base and protruding from the yoke base, wherein a plurality of the magnets constituting the first surface are fixed to one surface of the yoke plate portion, and a plurality of the magnets constituting the second surface are fixed to the other surface of the yoke plate portion.

4. A linear motor as described in claim 1 or 2, wherein the mover further has a component mounting head that is detachable from the base, the first position adjustment mechanism has a first operating part that adjusts the position of the first coil, and the second position adjustment mechanism has a second operating part that adjusts the position of the second coil, and when the component mounting head is detached from the base, the first operating part and the second operating part are exposed.

5. The linear motor according to claim 4, wherein the base has an opening, the first operating unit and the second operating unit are disposed within the opening, and the opening is exposed when the component mounting head is removed from the base.

6. A linear motor according to claim 1 or 2, wherein the magnet rail is arranged with the first surface facing upward.

7. A method for adjusting the positions of the first coil and the second coil of a linear motor as defined in claim 1 or 2, comprising the steps of: adjusting the position of the first coil by the first position adjustment mechanism; and adjusting the position of the second coil by the second position adjustment mechanism, in a state in which the magnet rail is oriented with the first surface facing upward, the first coil is arranged on the top of the magnet rail, and the second coil is arranged on the bottom of the magnet rail.

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