WO2009145112A1

WO2009145112A1 - Linear motor

Info

Publication number: WO2009145112A1
Application number: PCT/JP2009/059379
Authority: WO
Inventors: 廣昭望月
Original assignee: Thk株式会社
Priority date: 2008-05-30
Filing date: 2009-05-21
Publication date: 2009-12-03
Also published as: TW201008089A; JPWO2009145112A1

Abstract

A linear motor configured such that an internal load is prevented from acting on a linear guide when a slide table is thermally expanded by heat generated from a coil. A displacement absorbing mechanism (10) consisting of multi-layer rubber is mounted between the upper surface of a linear guide (6) and the lower surface of a slide table (2). The displacement absorbing mechanism (10) has vertical rigidity which can, when attraction force acts between a coil (4) and a magnet (3), secure a gap, in which a liner motor operates, between the coil (4) and the magnet (3). Also, when heat is generated from the coil (4) to cause the slide table (2) to thermally expand in the lateral direction thereof, the displacement absorbing mechanism (10) deforms under shear to relax a force acting from the slide table (2) to the linear guide (6).

Description

Linear motor

The present invention relates to a linear motor that obtains a thrust for linear movement of a mover by a magnetic field generated in a magnet and a current flowing in the coil, and in particular, a pair of slide tables to which a coil is attached are arranged on both sides of the coil. The present invention relates to a linear motor guided by a guide unit.

This type of linear motor includes a fixed member having a magnet in which N-pole and S-pole magnetic poles are alternately arranged in one axis direction, a slide table having a three-phase coil facing the magnet via a magnetic clearance, A pair of linear guides for guiding the slide table to linearly move in a uniaxial direction with respect to the fixed member in a state in which the clearance between the magnet and the coil is kept constant. Each linear guide is attached to a fixed member, a track rail attached to the slide table, and a movable block assembled to the track rail so as to be linearly movable, and interposed between the track rail and the movable block so as to allow rolling motion. A plurality of balls.

When a three-phase alternating current is passed through a three-phase coil, a thrust for linear movement of the slide table is generated by the magnetic field generated in the magnet and the current flowing in the coil. The thrust of the linear motor is proportional to the product of the magnetic flux density B generated in the magnet and the current I flowing through the coil. By increasing the current I flowing through the coil, the thrust can be increased and the slide table can be moved at high speed. However, when the current I is increased, Joule heat proportional to the square of the current is generated, and the coil generates heat. When the heat generated by the coil is transmitted to the slide table, the slide table is thermally expanded. Since the thermal expansion amount of the slide table is larger than the thermal expansion amount of the fixing member, an internal load is generated in the pair of linear guides arranged on both sides in the width direction of the slide table. Since the ball interposed between the track rail of the linear guide and the moving block is deformed, the movement and life of the linear guide are adversely affected.

In order to solve this problem, Patent Document 1 discloses a linear motor in which heat dissipation means for preventing heat generation of the coil from being transmitted to the slide table is provided between the coil and the slide table (Patent Document 1). ).

JP 2008-67492 A (see page 2, claim 1)

As described in Patent Document 1, in the conventional linear motor of this type, there has been devised how heat generated in the coil is not transmitted to the slide table. No measures were taken when heat was transferred to the slide table and the slide table thermally expanded. This is because, in this type of linear motor, even if an attractive force is applied between the coil and the magnet, it is necessary to ensure a minute gap between them. In other words, since the vertical rigidity of the part that guides the slide table needs to be increased and a clearance is required, a linear guide with a high vertical rigidity is used, and the track rail of the linear guide is directly coupled to the upper surface of the fixing member. This is because the moving block of the linear guide is directly coupled to the lower surface of the slide table.

Therefore, an object of the present invention is to provide a new linear motor capable of preventing an internal load from acting on the linear guide when the slide table is thermally expanded due to heat generation of the coil.

In order to solve the above problems, the invention described in claim 1 is directed to a first member having a magnet in which N-pole and S-pole magnetic poles are alternately arranged in a uniaxial direction, and opposed to the magnet via a gap. The second member moves linearly relative to the first member in the uniaxial direction with the coil, the second member to which the coil is attached, and the coil and the magnet maintaining the clearance. And a pair of guide portions disposed on both sides in the width direction of the second member across the coil, and at least one of the pair of guide portions in a state where the uniaxial direction is disposed in a horizontal plane A displacement absorbing mechanism interposed between the upper surface and the lower surface of the second member, or between the upper surface of the first member and at least one lower surface of the pair of guide portions, the displacement absorbing mechanism comprising: ,in front When an attractive force acts between the coil and the magnet, it has a vertical rigidity that can secure a clearance for the linear motor to operate, the coil generates heat, and the second member expands in the width direction. In this case, the linear motor is deformed so as to relieve the force acting in the width direction from the second member to the guide portion.

According to a second aspect of the present invention, in the linear motor according to the first aspect, the displacement absorbing mechanism includes a first attachment body attached to the upper surface of the guide portion or the upper surface of the first member, and the second A second attachment body attached to the lower surface of the member or the lower surface of the guide portion, and interposed between the first attachment body and the second attachment body, and the second member is thermally expanded in the width direction. And a shear deformation layer including at least one rubber layer that undergoes shear deformation.

According to a third aspect of the present invention, in the linear motor of the second aspect, the second mounting body and the shear deformation layer have a counterbore for forming a seating surface of a bolt on the first mounting body. A hole is opened, and the first attachment body is attached to the upper surface of the guide portion or the upper surface of the first member by a bolt passed through the counterbore hole, and the second attachment body includes the second attachment body. A mounting screw or a mounting hole for mounting the lower surface of the member or the lower surface of the guide portion to the second mounting body is formed.

According to a fourth aspect of the present invention, in the linear motor according to the second or third aspect, the vertical rigidity of the displacement absorbing mechanism is equal to or greater than the vertical rigidity of the guide portion. .

The invention according to claim 5 is the linear motor according to

claim

1 or 2, wherein the displacement absorbing mechanism is disposed between the upper surface of the guide portion and the lower surface of the second member, and the guide portion is A track rail coupled to the upper surface of the first member; a moving block coupled to the lower surface of the displacement absorbing mechanism and assembled to the track rail so as to be relatively linearly movable; and the track rail and the movement And a plurality of rolling elements interposed between the blocks so as to allow rolling motion.

According to a sixth aspect of the present invention, in the linear motor according to the first or second aspect, the displacement absorbing mechanism is attached to only one of the pair of guide portions arranged with the coil interposed therebetween. It is characterized by being able to.

Since a displacement absorbing mechanism is provided between the first member or the second member and the guide portion to relieve the force acting in the width direction from the second member to the guide portion, the second member is thermally expanded by the heat generated by the coil. However, it is possible to prevent an internal load from acting on the guide portion. In addition, since the displacement absorbing mechanism has a vertical rigidity that can secure a clearance in which the linear motor operates, the displacement absorbing mechanism is compressed in the vertical direction without adversely affecting the operation of the linear motor.

The perspective view of the linear motor of one Embodiment of this invention Front view of the linear motor Top view of magnet Three-phase coil and core perspective view Perspective view of linear guide (including partial cross-sectional view) Perspective view of laminated rubber and linear guide Perspective view of laminated rubber Detailed view of laminated rubber ((a) shows a plan view, (b) shows a side view) Side view showing laminated rubber with suction force Conceptual diagram showing the rigidity of laminated rubber Side view showing laminated rubber with shear deformation The perspective view which shows the other example of the laminated rubber attached to the side of a linear guide Graph comparing the rigidity of linear guide and laminated rubber Diagram showing the mounting position of the displacement sensor to the linear motor Graph showing temperature rise of three-phase coil Graph showing slide table displacement Graph showing slide table displacement

Hereinafter, a linear motor according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show a linear motor according to an embodiment of the present invention. FIG. 1 is a perspective view of the linear motor, and FIG. 2 is a front view of the linear motor as viewed from the moving direction of the slide table. The linear motor is a single-axis actuator and linearly moves the slide table 2 with respect to the fixed member 1. A plurality of N-pole and S-pole magnets 3 are alternately arranged in the uniaxial direction on the fixed member 1. The three-phase coil 4 coupled to the lower surface of the slide table 2 (more precisely, the core 5 inserted into the three-phase coil 4) faces the magnet 3 via a gap g where a magnetic field acts. The magnetic field generated in the magnet 3 and the three-phase alternating current flowing in the three-phase coil 4 generate a thrust that causes the slide table 2 to move linearly.

The fixing member 1 has an elongated bottom plate 1a in a uniaxial direction and a pair of side wall portions 1b provided at both ends in the width direction of the bottom plate 1a. A linear guide 6 as a guide portion is attached to the upper surface of each of the pair of side wall portions 1b. The linear guide 6 includes a track block 7 and a moving block 8 assembled to the track rail 7 so as to be capable of relative movement, and a plurality of balls 9 interposed between the track rail 7 and the moving block 8 so as to be capable of rolling motion (see FIG. 5). And). The track rail 7 extends elongated along the side wall 1b.

FIG. 3 is a plan view of a plurality of magnets 3 arranged on the fixing member 1. On the upper surface of the bottom plate 1a of the fixing member 1, N-pole or S-

pole magnets

3a and 3b are alternately arranged at a constant pitch. Each

magnet

3a, 3b consists of a plate-like permanent magnet elongated in the width direction. N or S poles are magnetized on the surfaces of the

magnets

3a and 3b. In order to make the magnetic field generated in the plurality of magnets 3 arranged in the uniaxial direction approach a sine wave, the

magnets

3a and 3b are formed in a parallelogram. The magnet 3 is covered with a cover plate 3c as necessary.

As shown in FIGS. 1 and 2, the slide table 2 is formed in a rectangular shape that is elongated in the width direction. The moving blocks 8 of the linear guide 6 are attached to both ends in the width direction of the slide table 2. Two moving blocks 8 are assembled with respect to one track rail 7, and the slide table 2 is supported by the moving blocks 8 at the four corners.

At the corner of one end in the width direction of the slide table 2, a notch 2a to which the moving block 8 is attached is formed. The laminated rubber 10 as a displacement absorbing mechanism is accommodated in the notch 2a. One end in the width direction of the slide table 2 is attached to the moving block 8 via a laminated rubber 10. The other end in the width direction of the slide table 2 is directly attached to the upper surface of the moving block 8. A through hole (not shown) for attaching the slide table 2 to the moving block 8 or the laminated rubber 10 is formed in the slide table 2. The slide table 2 can be attached to the moving block 8 or the laminated rubber 10 by passing a bolt through the through hole and tightening the bolt into the screw hole of the moving block 8 or the laminated rubber 10.

A three-phase coil 4 and a core 5 serving as armatures are attached to the center of the lower surface of the slide table 2. FIG. 4 is a perspective view of the three-phase coil 4 and the core 5. The material of the core 5 is a magnetic material such as silicon steel. The core 5 has three comb teeth 5 a that strengthen the magnetic field generated in the three-phase coil 4. The U / V / W phase three-phase coil 4 includes three coils 4 a wound around three comb teeth 5 a of a core 5. The three coils 4a are arranged in the moving direction of the slide table. A radiating fin that releases heat generated from the three-phase coil 4 to the atmosphere may be attached to the core 5. When a three-phase alternating current having a phase difference of 120 ° is passed through the three-phase coil 4, thrust is generated by the action of the magnetic field generated in the three-phase coil 4 and the magnetic field generated in the magnet 3.

The current flowing through the three-phase coil 4 is controlled by a servo driver. A linear scale for detecting the position of the slide table 2 is attached to the fixed member 1. The servo driver feeds back the position information and speed information of the slide table 2 detected by the linear scale, calculates a difference from the target value, and adjusts the position of the three-phase coil 4 so that the position and speed of the slide table 2 approach the target value. Controls three-phase alternating current.

FIG. 5 shows a perspective view of the linear guide 6. The linear guide 6 is interposed between the upper surface of the side wall portion 1 b of the fixing member 1 and the lower surface of the slide table 2. A track rail 7 is attached to the upper surface of the side wall 1 b of the fixing member 1. A plurality of mounting holes 7b are formed in the track rail 7 at a predetermined pitch in the longitudinal direction. By passing a bolt through the mounting hole 7b and screwing the bolt into the screw hole of the side wall 1b of the fixing member 1, the track rail 7 is fixed to the side wall 1b. The track rail 7 is formed with a plurality of ball rolling grooves 7a on which the balls 9 roll along the longitudinal direction. The cross-sectional shape of the ball rolling groove 7a is a circular arc groove shape made of a single arc slightly larger than the radius of the ball 9, or a Gothic arch groove shape made of two arcs. The ball rolling groove 7 a is formed not only on the side surface of the track rail 7 but also on the upper surface of the track rail 7. By forming the ball rolling groove 7 a on the upper surface of the track rail 7, the vertical rigidity of the linear guide 6 can be increased.

The moving block 8 is formed in a bowl shape straddling the track rail 7. In the moving block 8, a load ball rolling groove 8a facing the ball rolling groove 7a of the track rail 7 is formed, and a ball circulation path including the load ball rolling groove 8a is formed. The ball circulation path includes a ball return path 13 extending in parallel with the load ball rolling groove 8a, and a U-shaped direction change path 14 connecting the end of the load ball rolling groove 8a and the end of the ball return path 13. The whole is formed in a circuit shape. A plurality of balls 9 are arranged and accommodated in the ball circulation path.

When the moving block 8 is moved relative to the track rail 7, the ball interposed between the ball rolling groove 7a of the track rail 7 and the load ball rolling groove 8a of the moving block 8 rolls. The ball 9 that has rolled to one end of the loaded ball rolling groove 8a is guided to the direction changing path 14, passes through the ball return path 13 and the opposite direction changing path 14, and then to the other end of the loaded ball rolling groove 8a. Returned. By interposing the ball 9 between the track rail 7 and the moving block 8, the resistance when the moving block 8 moves with respect to the track rail 7 can be reduced.

The heat generated by the three-phase coil 4 is transmitted to the linear guide 6 via the slide table 2. For this reason, a linear guide 6 that can withstand high temperatures is used. Specifically, a stainless steel plate is used for the end plate 15 in which the direction changing path 14 is formed, and a stainless steel plate is also used for the holding plate 16 that prevents the balls 9 from falling off.

FIG. 6 is a perspective view of the linear guide 6 and the laminated rubber 10 attached to the upper surface of the linear guide 6. The laminated rubber 10 is obtained by laminating a metal plate and a rubber layer. The laminated rubber 10 includes a first attachment body 21 attached to the upper surface of the moving block 8, a second attachment body 22 attached to the lower surface of the slide table 2, and the first attachment body 21 and the second attachment body 22. And a shear deformation layer 23 interposed therebetween. The shear deformation layer 23 is composed of two upper and lower rubber layers 24 and a metal plate 25 interposed between the rubber layers 24.

7 and 8 show detailed views of the laminated rubber 10. FIG. The second mounting body 22 and the shear deformation layer 23 of the laminated rubber 10 are provided with counterbore holes 22b for exposing the bolt bearing surface 22a to the first mounting body 21. The counterbore 22b is formed at a position corresponding to the screw hole 8b (see FIG. 5) of the moving block 8. The first mounting body 21 is provided with a through hole 21a through which a screw portion of a bolt is passed in order to fasten the first mounting body 21 to the moving block 8. The first attachment body 21 is attached to the upper surface of the moving block 8 by a bolt passed through the counterbored hole 22b.

The inner diameter of the counter bore 22b is larger than the outer diameter of the bolt head. A clearance enough to deform the shear deformation layer 23 is formed around the head of the bolt. The head of the bolt also functions as a stopper when the shear deformation layer 23 undergoes shear deformation by a predetermined amount or more. That is, the head portion of the bolt comes into contact with the shear deformation layer 23 that has undergone shear deformation for a predetermined amount or more, and the shear deformation of the shear deformation layer 23 for a predetermined amount or more is prevented.

A mounting screw 22 c for fastening the slide table 2 to the second mounting body 22 is also formed on the second mounting body 22. The mounting screw 22c is formed outside the counterbore hole 22b at a position away from the upper surface of the moving block 8. Instead of the mounting screw 22c, a through hole through which a bolt is inserted may be formed.

When attaching the laminated rubber 10 to the linear guide 6, the laminated rubber 10 is first placed on the moving block 8, bolts are passed through the counterbored holes 22 b of the laminated rubber 10, and the first attachment body 21 of the laminated rubber 10 is moved to the moving block 8. Fasten to the top surface. At this time, the shear deformation layer 23 and the second attachment body 22 are not fastened to the moving block 8. Next, the slide table 2 is placed on the upper surface of the laminated rubber 10, a bolt is passed through the mounting hole of the slide table 2, the bolt is screwed into the mounting screw 22c of the second mounting body 22, and the slide table 2 is mounted on the second mounting body. Fasten to 22.

By forming counterbored holes 22b in the laminated rubber 10, when the laminated rubber 10 and the slide table 2 are attached to the moving block 8, screwing from above is possible, and the laminated rubber 10 and the slide table 2 can be easily attached. become. Moreover, the laminated rubber 10 can be spread over the entire upper surface of the moving block 8 in a limited space. As shown in FIG. 9, the rigidity in the vertical direction of the laminated rubber 10 is related to (area A of the rubber layer 24) / (surface area S around the rubber layer 24). The horizontal rigidity of the laminated rubber is related to (the horizontal length L of the rubber layer 24) / the total thickness t of the rubber layer 24. By forming counterbored holes in the laminated rubber 10, the degree of freedom in designing the laminated rubber 10 is widened, and it is easy to increase the vertical rigidity and reduce the horizontal rigidity of the laminated rubber 10.

The rubber layer 24 of the laminated rubber 10 and the first and

second attachment bodies

21 and 22 and the rubber layer 24 and the metal plate 25 are vulcanized and bonded. The surfaces of the metal first and second mounting

bodies

21 and 22 and the metal plate 25 are roughened by shot blasting, these are inserted into a mold, rubber is press-fitted into the mold cavity, and pressure is applied to the rubber. These can be vulcanized and bonded by vulcanization while adding. In addition, you may adhere | attach the rubber layer 24 and the metal plate 25 using an adhesive agent.

FIG. 10 shows the deformation of the laminated rubber 10 when a vertical suction force is applied, and FIG. 11 shows the deformation of the laminated rubber 10 when a horizontal shear force is applied. The vertical rigidity of the laminated rubber 10 is such that when a suction force acts between the three-phase coil 4 and the magnet 3, a clearance that allows the linear motor to operate can be secured between the three-phase coil 4 and the magnet 3. Set high. The smaller the clearance between the three-phase coil 4 and the magnet 3, the higher the thrust of the linear motor, so the clearance between the three-phase coil 4 (more precisely, the core 5) and the magnet 3. g is set minutely. The vertical rigidity of the laminated rubber 10 is set so that the amount of change in the clearance g falls within a predetermined range so that the core 5 and the magnet 3 do not come into contact with each other due to the attractive force.

Here, by reducing the thickness of the rubber layer 24 of the laminated rubber 10, increasing the cross-sectional area of the rubber layer 24, or interposing the metal plate 25 between the rubber layers 24, the vertical direction of the laminated rubber 10 is increased. Directional rigidity can be increased. In this embodiment, the thickness of the rubber layer 24 is set to 0.5 to 1.5 mm, for example, and the thickness of the metal plate is set to about 0.5 to 1.5 mm, for example. The cross-sectional areas of the rubber layer 24 and the metal plate 25 are matched to the area of the upper surface of the moving block 8. If the rubber layer 24 is formed in one layer, the rigidity can be further increased, but the amount of shear deformation in the horizontal direction is reduced. In order to increase the amount of shear deformation, the rubber layer 24 is made into two layers. As described above, the spring constant of the laminated rubber 10 in the compression direction can be set to, for example, 100,000 to 200,000 N / mm, which is equal to or greater than the spring constant of the linear guide 6 in the compression direction. When the spring constant in the compression direction of the linear guide 6 is k1 and the spring constant in the compression direction of the laminated rubber 10 is k2, the overall spring constant k connecting the linear guide 6 and the laminated rubber 10 in series is 1 / k = 1. / K1 + 1 / k2. By making the spring constant of the laminated rubber 10 equal to or greater than the spring constant of the linear guide 6, it is possible to suppress a decrease in the overall spring constant.

As shown in FIG. 11, the laminated rubber 10 undergoes shear deformation in the horizontal direction when the slide table 2 is thermally expanded. The spring constant in the shear direction is set to, for example, 500 to 2000 N / mm which is 1/100 or less of the spring constant in the compression direction so that the laminated rubber 10 is easily sheared. Thereby, the amount of shear deformation in the horizontal direction can be made 100 times or more larger than the amount of compression in the vertical direction.

When the temperature of the slide table 2 rises by 100 ° C. or more due to the heat generated by the three-phase coil 4, the slide table expands by 0.1 to 0.2 mm, for example. Since the allowable deformation amount of the ball 9 incorporated in the linear guide 6 is about several tens of μm, if the thermal expansion amount of the slide table 2 acts on the ball 9 as it is, the life of the ball 9 is extremely shortened. By interposing the laminated rubber 10 between the moving block 8 and the slide table 2, even if the slide table 2 is thermally expanded, the force in the width direction of the slide table 2 transmitted from the slide table 2 to the moving block 8 is reduced. be able to. The spring constant in the shear direction of the laminated rubber 10 is set so that the load applied to the ball 9 is less than the allowable load. The allowable load of the ball 9 is calculated from the static load rating or the dynamic load rating of the linear guide 6.

As shown in FIG. 2, of the pair of left and right linear guides 6, the laminated rubber 10 is attached to only one linear guide 6. The slide table 2 is directly fixed to the moving block 8 on the remaining moving block 8 of the linear guide 6 without using the laminated rubber 10. For this reason, the rigidity (see FIG. 1) with respect to the yawing moment of the slide table 2 is kept high.

Note that the laminated rubber 10 shown in FIG. 6 is characterized by high vertical rigidity and large horizontal shear deformation. For this reason, the slide table 2 can be guided with high rigidity in the vertical direction, and mounting errors of the two parallel track rails 7 can be absorbed. In addition, when the heavy slide table 2 is attached to the laminated rubber 10, the rubber layer 24 reduces the impact, so that the slide table 2 can be easily attached. Therefore, this laminated rubber 10 may be used not only as a linear motor but also as a displacement absorbing mechanism for an actuator having two parallel track rails 7.

FIG. 12 shows a modified example of the laminated rubber 10 applied to the actuator. Depending on the application of the actuator in which the linear guide 6 is incorporated, it may be desired to increase the horizontal rigidity of the linear guide 6 and weaken the vertical rigidity. The laminated rubber 10 may be attached to the side surface of the moving block 8 so that the rigidity-soft property can be selected between the vertical direction and the horizontal direction according to the application.

A laminated rubber 10 having a spring constant of 150,000 N / mm in the compression direction and a spring constant of 1250 N / mm in the shear direction was prepared. FIG. 13 shows a conceptual diagram of the spring characteristics of the laminated rubber 10 in the compression direction and shear direction. The rigidity of the laminated rubber 10 in the compression direction is higher than the rigidity of the linear guide 6 in the compression direction. The rigidity of the laminated rubber 10 in the shear direction is lower than the rigidity of the linear guide 6 in the compression direction.

Then, as shown in FIG. 14, the laminated rubber 10 was interposed between the slide table 2 and the moving block 8. A current was passed through the three-phase coil 4 to operate the linear motor. As shown in FIG. 15, the three-phase coil 4 rose to about 110 ° C. over time.

Next, it was measured how the slide table 2 and the linear guide 6 were displaced in the horizontal direction as the temperature of the three-phase coil 4 increased.

FIG. 16 shows the relationship between the elapsed time and the slide table 2 and the moving block 8 in the horizontal direction. On the side where the moving block 8 is directly fixed to the slide table 2 (the left side in FIG. 14), neither the moving block 8 nor the table is displaced significantly in the horizontal direction over time (subscripts in FIG. 16, B). reference). On the other hand, on the side where the laminated rubber 10 is interposed (the right side in FIG. 14), the slide table 2 and the moving block 8 are displaced by 140 μm in the horizontal direction as time elapses with the thermal expansion of the slide table 2 (FIG. 16). , A subscript).

Next, it was measured how the slide table 2 was displaced in the vertical direction as the temperature of the three-phase coil 4 increased.

17 shows the displacement in the vertical direction of the slide table 2 on the side where the moving block 8 is directly fixed to the slide table 2 (left side E in FIG. 14) and the side where the laminated rubber 10 is interposed (right side C in FIG. 14). ) And a central portion (center D in FIG. 14). It was found that the central part of the slide table 2 was displaced downward immediately after passing the current through the three-phase coil 4. The attraction force between the three-phase coil 4 and the magnet 3 was the largest at the center of the slide table 2 and was such that the center of the slide table 2 was deformed. On the right and left sides of the slide table 2, the vertical displacement did not change much over time. It can be seen that the laminated rubber 10 has sufficient vertical rigidity.

Here, when the laminated rubber 10 is not provided, the horizontal displacement of 140 μm acts on the linear guide 6 by the displacement of the slide table 2 in the horizontal direction of 140 μm. As a result, an internal stress of about 22 kN is generated in the linear guide 6. However, by providing the laminated rubber 10, the laminated rubber 10 undergoes shear deformation and absorbs horizontal displacement, so that only a 20 μm displacement acts on the linear guide 6. At this time, only an internal stress of about 2.3 kN, which is about 1/10, is generated in the linear guide 6. The function of the laminated rubber 10 as a displacement absorbing mechanism could be sufficiently confirmed.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, instead of a rubber-made displacement absorbing mechanism, an orthogonal linear guide combined so that a pair of track rails are orthogonal may be used. The orthogonal linear guide has a structure in which the moving blocks 8 of the pair of linear guides are back-to-back so that the track rails are orthogonal. If the clearance between the coil and the magnet can be secured by the rigidity in the vertical direction, the displacement absorbing mechanism is not provided between the upper surface of the linear guide and the lower surface of the slide table, but between the upper surface of the fixed member and the lower surface of the track rail. May be. Furthermore, a roller can be used instead of a ball for the rolling element of the linear guide. If a roller is used, the rigidity of the linear guide can be increased.

This specification is based on Japanese Patent Application No. 2008-143262 filed on May 30, 2008. All this content is included here.

DESCRIPTION OF SYMBOLS 1 ... Fixed member, 2 ... Slide table, 3 ... Magnet, 4 ... Three-phase coil, 5 ... Core, 6 ... Linear guide (guide part), 7 ... Track rail, 7a ... Ball rolling groove, 8 ... Moving block, 8a ... Loaded ball rolling groove, 9 ... Ball (rolling element), 10 ... Laminated rubber (displacement absorption mechanism), 13 ... Ball return path, 14 ... Direction change path, 21 ... First mounting body, 22b ... Counterbore hole , 22c ... mounting screw, 22a ... seating surface, 22 ... second mounting body, 23 ... shear deformation layer, 24 ... rubber layer, 25 ... metal plate

Claims

A first member having a magnet in which N-pole and S-pole magnetic poles are alternately arranged in one axis direction;
A coil facing the magnet via a gap;
A second member to which the coil is attached;
The second member guides the linear movement relative to the first member relative to the first member in a state where the coil and the magnet maintain the clearance, and the second member is sandwiched by the second member. A pair of guide portions disposed on both sides in the width direction of the member;
In a state where the uniaxial direction is arranged in a horizontal plane, between at least one upper surface of the pair of guide portions and the lower surface of the second member, or at least one of the upper surface of the first member and the pair of guide portions. A displacement absorbing mechanism interposed between the lower surface,
The displacement absorbing mechanism has a vertical rigidity capable of ensuring a clearance for operating the linear motor when an attractive force is applied between the coil and the magnet.
A linear motor that deforms so as to relieve a force acting in the width direction from the second member to the guide portion when the coil generates heat and the second member thermally expands in the width direction.
The displacement absorbing mechanism is
A first attachment body attached to the upper surface of the guide portion or the upper surface of the first member;
A second attachment body attached to the lower surface of the second member or the lower surface of the guide portion;
A shear deformation layer interposed between the first attachment body and the second attachment body and including at least one rubber layer that undergoes shear deformation when the second member is thermally expanded in the width direction; The linear motor according to claim 1, wherein the linear motor is provided.
In the second attachment body and the shear deformation layer, a counterbore hole for forming a seating surface of a bolt in the first attachment body is formed,
The first attachment body is attached to the upper surface of the guide portion or the upper surface of the first member by a bolt passed through the counterbore hole,
The mounting screw or mounting hole for mounting the lower surface of the second member or the lower surface of the guide portion to the second mounting body is formed in the second mounting body. The linear motor described.
4. The linear motor according to claim 2, wherein the vertical rigidity of the displacement absorbing mechanism is equal to or greater than the vertical rigidity of the guide portion.
The displacement absorbing mechanism is disposed between the upper surface of the guide portion and the lower surface of the second member,
The guide part is
A track rail coupled to the upper surface of the first member;
A moving block coupled to the lower surface of the displacement absorbing mechanism and assembled to the track rail so as to be relatively linearly movable;
The linear motor according to claim 1, further comprising a plurality of rolling elements interposed between the track rail and the moving block so as to be capable of rolling motion.
3. The linear motor according to claim 1, wherein the displacement absorbing mechanism is attached only to one guide portion of the pair of guide portions arranged with the coil interposed therebetween.