JP4811780B2 - Linear motor, machine tool and measuring instrument - Google Patents

Description

  The present invention relates to a linear motor, a machine tool, and a measuring instrument that can realize accurate driving.

In a machine tool, a measuring instrument, etc., a slide table is used for holding and positioning a work, a tool, a measuring element, or the like. A linear motor may be used as a feed driving means for such a slide table (see Patent Document 1).
JP 2002-346844 A JP 2003-189589 A

  Incidentally, one problem with linear motors is that cogging occurs. Cogging is thrust unevenness caused by a magnetic force generated between a coil and a permanent magnet, which may cause a response delay. Cogging occurs regardless of the presence or absence of current, which may reduce the positional accuracy of the linear motor, and may require extra current for driving and increase heat generation.

  As countermeasures for reducing cogging, there have been proposed a method of offsetting apparent cogging by providing an auxiliary pole in the movable magnet, a method of shifting the phases of each other by providing multiple units of linear motors, It only removes frequency components with cogging, and it has not been achieved to make cogging almost zero including harmonics.

  On the other hand, in Patent Document 2, cogging is performed by arranging a plurality of permanent magnets so that the positions of both ends of each permanent magnet in the moving direction are substantially shifted by the pitch of the teeth of the comb-like iron core. A linear motor for reducing the above is disclosed. However, the technique of Patent Document 2 is effective only for a linear motor having a comb-like iron core, and is not necessarily applicable to all linear motors.

  The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a linear motor that can reduce response delay and increase positioning accuracy.

The linear motor according to claim 1, wherein a plurality of permanent magnets arranged on one of a fixed body and a moving body and arranged at a predetermined pitch, and the other of the fixed body and the moving body face the permanent magnet. In a linear motor having a coil arranged as
It is arranged at a position to receive the magnetic force from the permanent magnet, and has a conductor having a length equal to or longer than the pitch of the permanent magnet ,
The said conductor is arrange | positioned with respect to the said coil in the row direction of the said permanent magnet, It is characterized by the above-mentioned.

In the linear motor of the present invention, the conductor and the permanent magnet move relative to each other so that the magnetic flux of the permanent magnet is traversed by relative movement, so that an induced current (eddy current) proportional to the speed thereof is obtained. The magnetic field generated by the current generates a magnetic force (induced electromotive force) by the magnetic field with the permanent magnet and becomes a drag force. Here, when the thrust acting on the moving body is P, the magnetic force due to the current of the coil is Fc (i), and the drag due to the induced current is Fe (v), the following equation (3) is established.
P = Fc (i) -Fe (v) (3)

  In the present invention, in order to generate the induced current, the permanent magnet that generates the driving force of the moving body by interaction with the magnetic force of the coil is used, so that the thrust direction by the magnetic force of the coil and the induction by the conductor Since the drag force caused by the current is almost on the same line and is in the opposite direction, there is an effect that an extra force that breaks the posture such as moment does not act on the moving body. Therefore, even if such a drag acts, the moving body can be smoothly moved with high accuracy.

  According to the equation (3), when the moving body is moving at a constant speed, the current of the coil becomes larger than that without the conductor. However, when the moving body is moving at a constant speed, if the speed of the moving body decreases due to, for example, friction, the induced electromotive force, that is, the drag force Fe that is proportional to the speed decreases, and the magnetic force Fc by the coil decreases. Even if it does not change, the effect that the thrust P increases so as to restore the speed v of the moving body occurs. On the other hand, when the speed of the moving body increases, the drag Fe proportional to this increases, and the thrust P decreases so as to reduce the speed of the moving body even if the current of the coil does not change. appear. As described above, by providing the conductor, an action of keeping the speed of the moving body constant is performed.

  Furthermore, in the supply of current to the coil, when speed feedback for detecting and controlling the speed of the moving body is applied, the induced electromotive force by the conductor complements its servo characteristics, so that the speed servo The same effect as increasing the gain can be obtained. That is, since the effect of suppressing the speed change by the conductor according to the present invention depends on the induced electromotive force, it occurs almost simultaneously with the speed change, but the response speed is, for example, a servo loop speed of a normal machine tool or the like. Much faster than ~ 200Hz. Therefore, since it acts so as to suppress even a high-speed speed change that cannot be followed by normal servo control, the effect of apparently setting the speed servo gain to be very high is produced. In addition, since the actual servo loop control has a completely different band, the effect can be exerted without generating any mutual interference with this action, and as a result, extremely stable motion accuracy of the moving body can be ensured. . In addition, the induced electromotive force generated by the conductor according to the present invention provides a drag force against the thrust, and a large current flows through the coil with the same current control resolution. Since a relatively large current change can be given to the change and the tracking error, the same effect as that obtained by increasing the loop gain can be obtained, and the moving body can be controlled with high accuracy.

  The present invention suppresses a rapid speed change of the moving body. This is because the area of the conductor is large, and the more the conductor crosses the magnetic flux of the permanent magnet with the movement of the moving body, the greater the drag is generated and the effect of suppressing the speed change becomes larger. That is, the magnitude of the generated drag can be controlled by changing the area crossed by the magnetic force of the conductor. Also, the smaller the internal resistance of the conductor, the less the loss of induced current due to Joule heat and the stronger the generated magnetic field, so that a large drag is generated and the effect of suppressing the speed change is increased. However, the conductor has a length longer than the pitch in the direction in which the permanent magnets are arranged (referred to as the length in the direction in which the permanent magnets are arranged), thereby increasing the effect of suppressing a sufficient speed change. it can.

  The conductor itself may be a metal material such as copper, and if attached to both sides so as to sandwich the coil, the transverse magnetic flux does not change even by relative movement with the permanent magnet, and generates a drag that is exactly proportional to the speed. Therefore, it is preferable. Thus, a great effect can be obtained with extremely simple parts.

  When control is performed to change the speed of the moving body, an induced electromotive force of the conductor works to suppress the speed change, but this force depends on the current of the coil due to the size of the conductor and internal loss. Since it is always smaller than the magnetic force, the speed of the moving body can be controlled. However, a larger coil current change is required for this suppression effect than in the case where the conductor is not provided, and this apparently has the same effect as increasing the servo gain.

  In addition, when the gain is increased by the servo loop, the noise becomes large and the oscillation easily occurs. However, in the case of the present invention, the instantaneous speed change is smoothly suppressed, which corresponds to this noise. The side effects are small and the control accuracy can be improved as expected.

The linear motor according to claim 2 is:
A plurality of permanent magnets arranged at one of a fixed body and a movable body and arranged at a predetermined pitch;
A coil disposed on the other of the fixed body and the movable body;
Wherein having said predetermined pitch over the length of the permanent magnet, which have a, a conductor disposed at a position opposed to the permanent magnet,
The said conductor is arrange | positioned with respect to the said coil in the row direction of the said permanent magnet, It is characterized by the above-mentioned.

  According to the present invention, in addition to the effect of the invention described in claim 1, by arranging the conductor at a position facing the permanent magnet, an induced electromotive force can be efficiently generated while having a compact configuration. Can do.

  According to a third aspect of the present invention, in the invention according to the first or second aspect, the conductor is disposed at a position facing the permanent magnet and on a side where the coil is disposed. Features. Here, the “side where the coil is arranged” means that the side fixed to the moving body is the same as the fixed body provided with the coil when a plurality of permanent magnets are provided on the moving body. In the case where a plurality of permanent magnets are provided on the fixed body, this means that the permanent magnet is on the side that is moved integrally with the moving body provided with the coil. Thus, the conductor arranged on the side where the coil is arranged may be provided integrally with the coil or in the vicinity of the coil, and may be provided separately from the member provided with the coil. You may take it.

In particular, the conductor is in the arrangement direction of the permanent magnet, when being arranged on opposite sides with respect to the coil, it is possible to generate a good balance drag on both sides of the coil.

A linear motor according to a fourth aspect is the invention according to any one of the first to third aspects, wherein the length of the conductor disposed on one side with respect to the coil in the arrangement direction of the permanent magnets is determined. A, when the length of the conductor arranged on the other side is B and the length of the coil is C, the arrangement length M of the plurality of permanent magnets and the driving stroke S of the moving body There is a relationship satisfying the following formula between them.
M + S ≦ A + B + C (1)
M−C ≧ S (2)

  By satisfying the relationship of the expression (1), an induced electromotive force proportional to the speed can be generated between the conductor and the permanent magnet at any position in the stroke range in which the moving body moves. . Consider a case where the permanent magnet moves relatively when the coil is located at the center of the arrangement of the permanent magnets. At this time, in the conductor on one side where the arrangement of the permanent magnets and the overlapping part in the driving direction decreases, the induced electromotive force does not occur in proportion to the decrease, but in the conductor on the other side Since the overlapping of the driving force direction with the permanent magnet increases by the same amount as the decrease, the sum of the induced electromotive forces (drags) generated in each of them hardly changes. Accordingly, a drag proportional to the speed of the moving body can be stably obtained. That is, it can be said that it is desirable to satisfy the formula (1) in order to obtain the effect of the present invention over the entire range of the moving stroke. Formula (2) is a necessary condition for the coil not to protrude from the arrangement of the permanent magnets over the entire range of the moving stroke.

The linear motor according to a fifth aspect is the invention according to any one of the first to fourth aspects, wherein the permanent magnets are arranged in two rows, and the coil and the conductor are arranged between the rows of the permanent magnets. It is characterized by being arranged.

A linear motor according to a sixth aspect is the invention according to any one of the first to fourth aspects, wherein the permanent magnet is cylindrical or columnar, and the coil and the conductor are arranged around the permanent magnet arranged side by side. It is characterized by being arranged.

  The so-called shaft motor is characterized by the fact that a coil is provided around a shaft-shaped permanent magnet via a gap, so that the thrust of the permanent magnet acts only on the magnetic field in the axial direction of the coil. There is virtually no force in the orthogonal direction. In other words, even if the alignment of the shaft-shaped permanent magnet is slightly tilted with respect to the moving direction, as long as the clearance with the coil is maintained and is not in contact with the permanent magnet of the shaft, the moving characteristics of the moving body are affected. Don't give. Therefore, according to the present invention, a linear motor in which the setting of the permanent magnet and the coil of the shaft is easy is configured.

  When a cylindrical conductor is provided for the coil and integrated, when the shaft-like permanent magnet and the coil move relatively, an induced current proportional to the speed acts in the conductor to generate a magnetic field. Make and work as a drag. Since this drag is proportional to speed, it works to suppress this against speed changes. In other words, when the coil and the conductor, or the permanent magnet side of the shaft are moving relative to each other at a constant speed, the induced electromotive force works as a constant drag, so that the driving force due to the coil current is greater than that without such a conductor. growing. That is, the thrust P acting on the moving body is similarly expressed by Expression (3). In this state, when the speed of the moving body decreases due to friction or the like, the induced electromotive force, that is, the drag Fe proportional to the speed decreases, and the speed V of the moving body is restored even if the magnetic force Fc by the coil does not change. The thrust P increases.

A linear motor according to a seventh aspect is the invention according to any one of the first to sixth aspects, wherein the coil and the conductor are fixed to the fixed body, and the permanent magnet is fixed to the movable body. The moving body moves relative to the fixed body by supplying electric power to the coil.

  Wiring for supplying current to the coil and piping for cooling the coil need to be assembled with piping such as cooling water. However, when the coil and the conductor are fixed to the moving body, the wiring and piping Must be moved together with the moving body, and the configuration for realizing the movement is complicated, and there is a possibility that these may become an obstacle or a drag during movement. On the other hand, when the permanent magnet is attached to the moving body, wiring and piping are not necessary, and it is very simple, but there is no fear of causing an obstacle to movement, which is preferable.

A machine tool according to claim 8 is a machine tool on which the linear motor according to any one of claims 1 to 7 is mounted, and the moving body is a slide table.

The machine tool according to claim 9 is the invention according to claim 8 , wherein the slide table is floated and held by static pressure.

  For example, since a machine tool having a slide table that can move very smoothly by the static pressure of a fluid such as oil or air is required to have a high accuracy of movement, by applying the linear motor of the present invention, High-precision slide table motion control can be realized.

The machine tool according to claim 10 is characterized in that, in the invention according to claim 8 or 9 , the optical surface of the optical element or the optical transfer surface of the optical element molding die for forming the optical element is processed. . An “optical transfer surface” refers to a surface that transfers an optical surface of an optical element.

  The processing of the optical surface or the optical transfer surface as used herein refers to processing that realizes a surface roughness of the processing surface of 5 nm or less in terms of an average surface roughness Ra. A machine tool intended for such processing needs to move or rotate the tool table or workpiece fixing table with extremely high accuracy. By applying the linear motor of the present invention, higher accuracy of motion can be achieved. Can be realized and machining accuracy can be improved.

A measuring instrument according to an eleventh aspect is a measuring instrument equipped with the linear motor according to any one of the first to seventh aspects, wherein the moving body is a slide table.

Instrument according to claim 12 is the invention according to claim 11, wherein the slide table is characterized by being floated held by static pressure.

  According to the present invention, it is possible to provide a linear motor that can reduce response delay and the like and increase positioning accuracy.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a 5-axis processing machine 10 as a machine tool to which the linear motor according to the present embodiment can be applied. The 5-axis processing machine 10 can process an optical surface of an optical element or an optical transfer surface of an optical element molding die for forming the optical element. In FIG. 1, an active air mount 11 supported by four legs 11a (only three are shown) on the floor F is a suppression means for suppressing the transmission of vibrations, and does not transmit floor vibrations to the base 12. Have

  On the rail 12a of the base 12 supported on the active air mount 11, a slide table 13 is provided so as to be movable in the Z-axis direction, and a turning table 14 is provided on the slide table 13 so as to be rotatable. The slide table 13 is supported with respect to the rail 12a, and the swivel table 14 is supported with respect to the slide table 13 with low friction using oil as a medium by static pressure guide (not shown).

  Further, on the base 12, a rail 15a spanned on the pair of support blocks 15 is provided with a slide table 16 that can move in the X-axis direction. The rail 16a on the slide table 16 has a Y-axis direction. A slide table 17 is provided so as to be movable, and a turning table 18 is provided on the slide table 17 so as to be rotatable. The slide table 16 is supported with respect to the rail 15a, the slide table 17 with respect to the rail 16a, and the swivel table 18 with respect to the slide table 17 with low friction using oil as a medium by static pressure guide (not shown). In addition, instead of placing a tool on the swivel table 18, a measuring instrument that can inspect the object to be measured placed on the swivel table 14, a camera, or the like is mounted, thereby forming a measuring instrument capable of high-precision measurement. It will be.

  In this embodiment, the slide tables 13, 16, and 17, which are the first work tables, are provided with a laser scale having a measurement resolution of 1 nm so that the amount of movement can be measured, and the frequency at which the servo gain is -3 dB. Is driven by a linear motor (described later) of 50 Hz (preferably 100 Hz) or higher. On the other hand, a rotary encoder with an angular resolution of 0.1 seconds is installed on the turntables 14 and 18 as the second work table so that the rotation angle can be measured. In the static pressure guide of the present embodiment, the oil viscosity is 2 poise and the supply pressure is 5 atm. At this time, the horizontal / vertical rigidity of the slide shaft was 1350 N / μm, which was a sufficient value.

The slide tables 13, 16, 17 and the swivel tables 14, 18 and the static pressure guide are made of silicon nitride. The swivel shaft is made of silicon nitride for the rotor portion and the stator portion is made of a special alloy having a linear expansion coefficient of 4 × 10 ⁻⁶ . It was. The support block 15 used Invar. The base 12 was used by welding a special alloy plate having a linear expansion coefficient of 4 × 10 ⁻⁶ . The Young's modulus of this special alloy is 130 GPa, but the rigidity necessary for the base surface was secured by setting the plate thickness to 40 mm.

  A workpiece having a free-form optical surface is attached to the swivel table 14, a diamond tool (not shown) is set on the swivel table 18, and the slide tables 13, 16, 17 and the swivel table 14 are simultaneously (with four axes) subjected to shaper cutting. went. The feed rate of the slide table 13 was 600 mm / min or more, and the processing time was 36 hours. The surface roughness of the cutting surface was Rmax 5 nm, and the shape accuracy was 57 nm, achieving a high accuracy approximately three times that of a commercially available multi-axis machine.

  FIG. 2 is a cross-sectional view (a cross-sectional view taken along line II-II in FIG. 1) of the slide table and the turntable in the present embodiment. In FIG. 2, on a rail support portion 12a of the base 12, a flat rail 12b made of ceramic and extending in a direction perpendicular to the paper surface is fixed. A slide table 13 made of ceramic and having a U-shaped cross section is disposed so as to cover the rail 12b.

  The slide table 13 is formed with static pressure pads (thin spaces or porous materials: the same applies hereinafter) 13a, 13a on the inner peripheral lower surface facing the upper surface of the rail 12b, and static pressure is applied on the inner peripheral side surface facing the side surface of the rail 12b. Pads 13b and 13b are formed, and static pressure pads 13c and 13c are formed on the inner peripheral upper surface facing the lower surface of the rail 12b. Each of the static pressure pads 13a to 13c is supplied with oil having a predetermined pressure from the outside through a hole 13d extending in the slide table 13. Note that an encoder (not shown) is fixed to the slide table 13. On the other hand, a sensor (not shown) is provided on the base 12 so as to face the encoder, and the slide table 13 moves relative to the base 12. The quantity can be measured with a resolution of 10 nm or less. The encoder and sensor constitute a measuring means.

  A support table 120 is fixed to the upper surface of the slide table 13. The support 120 is preferably an alloy such as invar in order to embed a coil or the like as will be described later, but ceramic can also be used if it can be processed.

  The substantially hollow cylindrical support 120 includes the turntable unit 14. More specifically, the turntable unit 14 connects a lower tooth shape portion 14a formed of a magnetic material and an upper disk portion 14b formed of ceramic via a disk-shaped reduced diameter portion 14f. It has a shape. The tooth profile portion 14a has a plurality of teeth formed on the outer periphery and is magnetized one tooth at a time, so that N poles and S poles are alternately arranged. Opposing to the teeth, the coil C is arranged on the inner peripheral surface of the support base 120 by one more than the number of teeth of the tooth profile portion 14a. The tooth profile portion 14a and the coil C constitute an AC servo motor.

  An encoder 14 c is fixed to the lower surface of the tooth profile portion 14 a, and on the other hand, a sensor 14 d is provided on the support table 120 so as to face the encoder 14 c, and the rotation angle of the turntable unit 14 with respect to the support table 120. Can be measured with a resolution of 1 sec or less.

  The support 120 is formed with an annular static pressure pad 120a on the lower surface of the upper flange 120f facing the upper surface of the tooth profile portion 14a, and an annular static pressure pad on the inner peripheral surface of the upper flange 120f facing the outer peripheral surface of the reduced diameter portion 14f. The pressure pad 120b is formed, and an annular static pressure pad 120c is formed on the upper surface of the lower flange 120e facing the lower surface of the tooth profile portion 14a. Each of the static pressure pads 120a to 120c is supplied with oil of a predetermined pressure from the outside through a hole 120d extending in the support base 120.

  FIG. 3 is a diagram showing a main part of the linear motor 50 according to the present embodiment that drives the slide table 13. The magnet case 51 disposed on the slide table 13 as a moving body (at a cross-sectional position different from that in FIG. 2) has a rectangular parallelepiped shape with a U-shaped cross section. In the magnet case 51, a plurality of permanent magnets MG are arranged so that N poles and S poles are alternately arranged at an equal pitch P along the axis, and the poles are different from each other with a gap therebetween. Opposed to each other.

A fixed body (in this case, the base 12 corresponds) on which the slide table 13 moves relatively is connected to a coil case 52 containing three coils CL and to both sides of the coil case 52 in the arrangement direction of the permanent magnets MG. Long plate-like conductors 53 and 53 are arranged. Although shown separately in FIG. 3, the coil case 52 and the conductors 53, 53 are inserted between the opposing rows of permanent magnets MG in the magnet case 51 via a gap. In the arrangement direction of the permanent magnets MG, the length of the coil case 52 is C, and the lengths of the conductors 53 and 53 are A, respectively. The width W1 of the coil case 52 is twice the width W2 of the conductors 53, 53. Here, when the arrangement length M of the permanent magnets and the driving stroke S of the slide table 13 are set, the following relationship is established.
M + S ≦ 2A + C
M-C ≧ S

  A cooling pipe 54 is connected to the conductor 53 on the front side in FIG. 3, and cooling water introduced from here into a cooling passage (not shown) in the conductor 53 cools the coil case 52, It is discharged from another cooling pipe 55 via a cooling passage (not shown) in the side conductor 53. The coil case 52 is connected to a wiring 56 for supplying power from an external power source (not shown) to the coil CL.

  The operation of this embodiment will be described. In FIG. 2, oil is discharged from the static pressure pads 13 a to 13 c by supplying oil to the pipe 13 d from an external hydraulic source, and using the static pressure, the slide table 13 mounted with the support 120 is It is supported in a non-contact state with respect to the rail 12b. 3 is driven in this state, the slide table 13 moves to a desired position with respect to the base 12.

  Furthermore, when the oil is supplied to the pipe 120d from an external hydraulic source, the oil is discharged from the static pressure pads 120a to 120c, and the rotary table unit 14 that supports the workpiece (not shown) using the static pressure is The support base 120 is supported in a non-contact state. In this state, by applying an alternating current to the coil C, the tooth profile portion 14a is magnetically driven, and the turning table unit 14 rotates by a desired angle with respect to the support base 120.

  FIG. 4 is a schematic diagram showing the operation of the linear motor 50 according to the present embodiment. When a current is supplied from the outside via the wiring 56 shown in FIG. 3, a magnetic field is generated in the coil CL, so that a magnetic force is generated between the permanent magnet MG and the coil CL, whereby the magnet case 51 is driven in the driving direction (permanent magnet). The slide table 13 is moved because the MG is biased in the horizontal direction in FIG.

  Here, when the conductors 53 and 53 and the permanent magnet MG move relative to each other, the conductors 53 and 53 cross the magnetic flux of the permanent magnet MG, so that an induced current (eddy current) VI proportional to the speed is generated. Since the magnetic field MF generated by the current generates a magnetic force (induced electromotive force) by the magnetic field with the permanent magnet MG and acts as a drag, it is possible to realize the movement of the slide table 13 without a response delay, so that highly accurate machining is performed. realizable. Furthermore, since the permanent magnet MG crosses the coil case 52 and the conductors 53 and 53 by the slide table 13 that slides very smoothly by static pressure, no wiring or piping for the coil is required on the slide table 13 side. Therefore, a simple configuration can be realized. Note that the linear motor 50 shown in FIG. 3 can also be used to drive the slide tables 16 and 17.

(Example 1)
In the machine tool shown in FIG. 3, two rows of plate-like permanent magnets with a pitch of 25 mm are attached to a static pressure slide table that is levitated by high-pressure oil, and a coil case extends between them. A copper plate was attached to the base side. Since the width of the copper body is half of the width of the permanent magnet, the magnetic flux that the conductor crosses with the movement of the slide table is about half of the magnetic force due to the coil current. The thrust requires 1.5 times the current. In other words, the loop gain can be set 1.5 times higher.

  FIG. 5 is a diagram illustrating a tracking error when the static pressure slide table is driven at a speed of 10 mm / min from the stopped state and stopped by the linear motor according to the embodiment. FIG. 6 is a diagram showing a tracking error when the static pressure slide table is driven and stopped at a speed of 10 mm / min from the stopped state by the linear motor according to the comparative example (with the conductor removed from the embodiment). In this state, the servo gain is adjusted. “Follow-up error” is the error in the position of the slide table relative to the command position. If this value is zero, the slide table is moving as commanded. It shows that an overshoot has occurred as it increases to the side.

  First, in the comparative example shown in FIG. 6, a tracking error occurs 10 nm or more in the delay direction at the moment of driving, and takes about 6 seconds and changes to almost zero. Further, at the moment of stopping, a tracking error occurs in the direction of overshooting by about 15 nm. Since the servo stability has deteriorated due to the absence of conductors, the loop gain has to be reduced, and as a result, the proportional gain decreases, the integration time constant increases, and the motion response of the slide table significantly decreases. became.

  On the other hand, in the embodiment shown in FIG. 5, it can be seen that the noise level is almost the same as that at the time of stoppage at the time of driving, and it moves with a tracking error of about several nm. In addition, only a few nanometers of tracking error occurs at the moment of driving or stopping. From FIG. 5 alone, there is no response delay, and the control of the slide table is so precise that it is impossible to know when the driving has stopped. Is realized.

  From the above, the effect of improving the feeding accuracy of the slide table by providing the conductor was actually confirmed.

(Example 2)
In the static pressure slide table used in Example 1, a distance of 100 mm was continuously reciprocated at a speed of 10 mm / min, and the temperature rise of the coil was measured. FIG. 7 is a graph showing the coil temperature on the vertical axis and the elapsed time from startup on the horizontal axis. The coil is cooled by water at 23 ± 0.1 ° C. The coil temperature was saturated with a temperature rise of about 0.7 ° C. after 2 hours. The temperature rise of the base was hardly detected at 0.1 ° C. or less. This is because the coil case is fixed to a much larger base, so the heat capacity is large, and the temperature-controlled hydrostatic oil is discharged from the hydrostatic surface and flows near the coil.

  Moreover, the temperature rise of the slide table to which the permanent magnet was attached was not clearly observed. It is judged that the coil is insulated by air with a gap of 1 mm or more, and the temperature is stabilized by circulation of static pressure oil flowing through the slide table.

  From the above, it has been found that the influence of thermal expansion and contraction of the base and the slide table accompanying the rise in coil temperature is so small that it can be ignored. From the above examples, it was proved that the linear motor according to the present invention can realize highly accurate moving body control only by adding a simple conductor component.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, the present invention can be applied to a shaft motor as shown in JP-A-2005-073419.

1 is a perspective view of a 5-axis machining apparatus 10 according to the present embodiment. It is sectional drawing of the slide table and turning table in this Embodiment. It is a figure which shows the principal part of the linear motor 50 concerning this Embodiment. It is a schematic diagram which shows operation | movement of the linear motor 50 concerning this Embodiment. It is a figure which shows a tracking error when driving a static pressure slide table by the speed of 10 mm / min from the stop state with the linear motor concerning an Example, and stopping. It is a figure which shows a tracking error when a static pressure slide table is driven and stopped at a speed of 10 mm / min from a stopped state by a linear motor according to a comparative example. It is a graph which shows coil temperature on the vertical axis | shaft and elapsed time after starting on the horizontal axis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 5-axis processing machine 11 Active air mount 12 Base 13 (Z axis) slide table 14 Turning table 15 Support block 16 (X axis) Slide table 17 (Y axis) Slide table 18 Turning table 50 Linear motor 51 Magnet case 52 Coil case 53 Conductor 54, 55 Piping 56 Wiring CL Coil MG Permanent magnet

Claims (12)

A linear having a plurality of permanent magnets arranged on one of the fixed body and the moving body and arranged at a predetermined pitch, and a coil disposed on the other of the fixed body and the moving body so as to face the permanent magnet. In the motor
It is arranged at a position to receive the magnetic force from the permanent magnet, and has a conductor having a length equal to or longer than the pitch of the permanent magnet ,
The linear motor according to claim 1, wherein the conductor is disposed on both sides of the coil in the direction in which the permanent magnets are arranged . A plurality of permanent magnets arranged at one of a fixed body and a movable body and arranged at a predetermined pitch;
A coil disposed on the other of the fixed body and the movable body;
Wherein having said predetermined pitch over the length of the permanent magnet, which have a, a conductor disposed at a position opposed to the permanent magnet,
The linear motor according to claim 1, wherein the conductor is disposed on both sides of the coil in the direction in which the permanent magnets are arranged .   The linear motor according to claim 1, wherein the conductor is disposed at a position facing the permanent magnet and on a side where the coil is disposed. In the arrangement direction of the permanent magnets, A is the length of the conductor disposed on one side of the coil, B is the length of the conductor disposed on the other side, and C is the length of the coil. when a, the sequence length M of the plurality of permanent magnets, between the drive stroke S of the movable body, claim 1-3, characterized in that there is a relationship that satisfies the following equation The linear motor described in 1.
M + S ≦ A + B + C (1)
M−C ≧ S (2) The permanent magnets are arranged in two rows, the conductor and the coil linear motor according to any one of claims 1 to 4, characterized in that disposed between the rows of said permanent magnets. The permanent magnet is cylindrical or columnar shape, and the conductor and the coil linear motor according to any one of claims 1 to 4, characterized in that disposed around the permanent magnet aligned. The coil and the conductor are fixed to the fixed body, the permanent magnet is fixed to the moving body, and the moving body moves relative to the fixed body by supplying electric power to the coil. linear motor according to any one of claims 1 to 6, characterized in that. A machine tool equipped with linear motor according to any one of claims 1 to 7 machine tool, wherein the moving body is a slide table. The machine tool according to claim 8 , wherein the slide table is floated and held by static pressure. The machine tool according to claim 8 or 9 , wherein the optical surface of the optical element or the optical transfer surface of an optical element molding die for forming the optical element is processed. A measuring instrument equipped with a linear motor according to any one of claims 1 to 7 instrument wherein the moving body is a slide table. The measuring instrument according to claim 11 , wherein the slide table is floated and held by static pressure.

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