JP2004129394A - Feed apparatus using linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a feed apparatus using a linear motor, capable of realizing high acceleration performance and cost reductions by eliminating deformation to a table or linear guide by the magnetic attraction of a linear motor and by reducing the weight of the table. <P>SOLUTION: A moving element 49 of a linear motor is installed on the table 66 via a pressing section 68 and a ball cage 72, without being fixed directly on the table 66. When the linear motor generates thrust by applying a current to the linear motor, the thrust is transmitted to the table 66 from the pressing section 68 via the ball cage 72 to drive the table 66 in the direction of an arrowhead 65. Even if magnetic attraction is produced at the linear motor, the structure of the pressing section 68 is such that the section 68 slides over the ball cage 72 and then slides in the direction of an arrowhead 74, which permits magnetic attraction to be developed, thus giving no influence on the table 66. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a feed device using a linear motor used for a machine tool or an industrial machine.
[0002]
[Prior art]
In recent years, with the speeding up of machine tools and industrial machines, feeders employing linear motors have come to be widely used. In a feed device of a type in which a ball screw is rotated by a brushless servomotor which is currently mainstream and a table attached to the ball screw moves in one axis direction, a feed speed of about 70 m / min is generally used. Thus, a feeder employing a linear motor achieves a high-speed feed of 400 m / min or more.
[0003]
On the other hand, a feeder using a linear motor has a so-called deflection system, such as a deflection in the rotation direction of a ball screw and a deflection of a coupling connecting a brushless servomotor and a ball screw, compared to a feeder of a type using a ball screw. Since the table is driven directly without the above, there is a feature that the positioning accuracy is superior to a feeder of a type using a ball screw.
[0004]
In a feeder using a general linear motor, a table is arranged on a fixed bed so as to be movable in one axis direction via a guide mechanism, and the bed and the table have a linear motor stator and a movable The child is fixed with a predetermined gap. In the linear motor arranged as described above, a current is applied to the winding wound on the stator or the mover to generate a thrust in the linear motor and move the table.
[0005]
FIG. 4 is a diagram showing a feeder using a linear motor according to the related art. FIG. 4A is a view of the feeder as viewed from a table slide direction, and FIG. 4B is a view of the feeder as viewed from a side surface perpendicular to the table slide direction. FIG. 5 is a sectional view of the feeder using the linear motor shown in FIG. 4 cut in the table sliding direction.
[0006]
The configuration and operation of a conventional linear motor feeder will be described with reference to FIGS.
[0007]
4 and 5, a table 46 is arranged on a fixed bed 40 via a rolling guide 42 so as to be movable in a direction of an arrow 44, and the bed 40 and the table 46 are each provided with a movable linear motor. The child 49 and the stator 50 are fixed with a predetermined gap. On the stator 50 of the linear motor, a plurality of permanent magnets 52 are arranged at predetermined intervals in the sliding direction of the table 46. A winding 54 is wound inside the mover 49. A field magnetic flux 56 is generated by the permanent magnet 52 disposed on the stator 50, and a current is applied to the winding 54, so that a thrust F corresponding to Fleming's left-hand rule F = magnetic flux density B × current I × winding The length L occurs, and the table 46 is driven.
[0008]
[Patent Document 1]
JP-A-8-192326 [Patent Document 2]
JP 2000-14120 [Problems to be solved by the invention]
However, the prior art described above has the following problems.
[0009]
In the prior art, a strong magnetic attraction force, generally three times or more the thrust, is generated between the mover 49 and the stator 50 of the linear motor. Therefore, in a feeder of a machine tool requiring particularly precise positioning, there is a problem that the table 46 and the rolling guide 42 are deformed by the magnetic attraction. On the other hand, in order to reduce the displacement due to the magnetic attraction force, the rigidity of the table 46 and the rolling guide 42 must be increased, which causes deterioration in acceleration performance due to an increase in the weight of the table 46 and an increase in cost. Was.
[0010]
As a technique for solving the above-mentioned problem, Japanese Patent Application Laid-Open Nos. 8-192326 and 2000-14120 propose a structure for preventing a table from being deformed by a magnetic attraction force of a linear motor.
[0011]
FIG. 6 is a diagram showing a feeding device disclosed in Japanese Patent Application Laid-Open No. 8-192326. According to the specification, "in accordance with this configuration, when a suction force is generated between the primary member 7 and the secondary member 9 by the magnetic perpendicular force of the linear motor, the horizontal piece 31d of the bracket 25 is cantilevered. Since the beam is a beam, the horizontal piece 29d is elastically deformed with the connecting portion with the mounting pedestal 27 as a bending point. 5d is prevented from being deformed by the suction force. "
[0012]
On the other hand, FIG. 7 is a diagram showing a feeding device disclosed in JP-A-2000-14120. The description states that “The electromagnetic force F1 in the Y direction acting between the coil 30a and the magnet 30b and the electromagnetic force F2 acting in the Y direction between the coil 31a and the magnet 31b may differ depending on the position of the housing 32. In such a case, a force of about 100 kg may be applied in the Y direction.In such a case, the ball of the bearing 34b is elastically deformed, and the housing 32 is displaced in the Y direction by several tens of μm. Since only the housing 32 is moved in the Y direction because it is connected to the table 3 via the elastic joint 35, the table 3 does not move in the Y direction. "
[0013]
However, the feeder using a linear motor disclosed in Japanese Patent Application Laid-Open No. 8-192326 cannot prevent the table 5d from being deformed by the magnetic attraction of the linear motor. This is because there is an air gap between the primary member 7 and the secondary member 9 corresponding to the mover and the stator of the linear motor so that the table 5d can move. Even if 29 is elastically deformed by magnetic attraction, the magnetic attraction acting between the mover 7 and the stator 9 of the linear motor does not decrease, and the table 5d and the bed 1d are deformed by the magnetic attraction. It is because. In addition, since the air gap between the mover 7 and the stator 9 is reduced by the elastic deformation of the horizontal piece 29, the magnetic attraction force is further increased, causing a problem that the table 5d and the bed 1d are further deformed. I do.
[0014]
Also, in the feeder of JP-A-2000-14120, similarly to the feeder of JP-A-8-192326, even if the elastic joint 35 is deformed, the distance between the coil 30a and the magnet 30b and the distance between the coil 31a and the magnet 31b are increased. , The magnetic attraction does not decrease, and the displacement of the table 3 cannot be prevented. Further, when the joint 35 is deformed, the air gap between the coil 30a and the magnet 30b and the air gap between the coil 31a and the magnet 31b are further unbalanced, the magnetic attraction force increases, and the displacement of the table 3 is further deteriorated. appear.
[0015]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide a feeder using a linear motor in which the deformation of a table or a linear guide due to the magnetic attraction of a linear motor is reduced.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a feeder using a linear motor has a stator having a linear motor, a first guide extending in a feed direction, and a bed having a second guide. A table supported by the first guide and slidably mounted on the bed; a movable element of a linear motor supported by the second guide and arranged to face the stator; and And a table driving member having a pressing portion that presses the sliding direction and slides in a direction perpendicular to the sliding direction.
[0017]
Further, it is preferable that the feed device includes a ball cage disposed between the pressing portion of the table driving member and the table.
[0018]
Further, it is preferable that the feeding device includes a slide guide disposed between the pressing portion of the table driving member and the table.
[0019]
Further, according to the present invention, a feeder using a linear motor, a stator of the linear motor, a first guide extending in the feed direction, a bed having a second guide, and the first, A table supported by a guide, slidably mounted on the bed, a table driving member supported by the second guide, and having a linear motor mover disposed opposite to the stator; and A connection member for connecting the drive member and the table, the connection member having high rigidity in a slide direction of the table and having low rigidity in a direction perpendicular to the slide direction.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
First embodiment.
FIG. 1 is a diagram showing a feeder using a linear motor according to the first embodiment. FIG. 1A is a diagram of the feeding device as viewed from a table sliding direction, and FIG. 1B is a diagram of the feeding device as viewed from a side surface perpendicular to the table sliding direction. This embodiment will be described with reference to FIG.
[0022]
First, the configuration of the device will be described. A bed 60 serving as a base of the apparatus is fixedly installed on a floor or the like. The upper surface of the bed 60 has two horizontal protrusions 61 extending in the horizontal direction. Both of the protrusions 61 extend in the table sliding direction. Further, grooves are formed on the upper surface and the left and right side surfaces of the convex portion 61 so as to be passages through which steel balls of a rolling guide 62 described later roll.
[0023]
A linear motor stator 50 is fixed to the bed 60. The stator 50 has a flat plate shape, and magnets 52 are arranged on the upper surface of the flat plate at predetermined intervals in the table sliding direction. Further, from both ends of the flat plate, two convex portions 51 are formed to protrude upward. These two streaks 51 also extend in the table sliding direction. Grooves that form passages for steel balls of the rolling guide 64 are also formed on the upper surface and the left and right side surfaces of these convex portions 51. The stator 50 may be manufactured as a separate component from the bed 60 and fixed to the bed 60, or may be manufactured from the same material as the bed 60 and be integrated.
[0024]
The table 66 has a flat upper part, and has four legs 67 projecting downward from four corners of the flat plate. A rolling guide 62 is fixed to the lower surface of each leg 67, and by engaging each rolling guide 62 with a convex portion of the bed 60, the table 66 extends the convex portion with respect to the bed 60. It is possible to slide in the provided direction (table sliding direction indicated by arrow 65 in the figure). A groove 70 is formed between the legs 67 of the table 66 arranged side by side in the sliding direction. In this groove 70, a ball cage 72 is disposed on each of the opposing surfaces of the leg 67. The ball cage 72 includes a plurality of steel balls arranged side by side and a retainer for holding the steel balls. The steel ball is rotatable with respect to the retainer. In addition, each surface which the leg part 67 opposes is a surface perpendicular | vertical with respect to a table sliding direction, Therefore, several steel balls are arrange | positioned side by side on the perpendicular surface.
[0025]
A table driving member 48 is arranged between the bed 60 and the table 66. The table driving member 48 includes a movable element 49 of a linear motor, a pressing portion 68 for pressing the table, and a rolling guide 64 that engages with a convex portion of the stator 50. Like the rolling guide 62, the two rolling guides 64 are engaged with the two stripes of the projections 51, and can slide the table driving member 48 in the table sliding direction.
[0026]
The mover 49 of the linear motor is arranged with a predetermined gap provided with respect to the magnet 52 arranged on the stator 50. The winding 54 shown in FIG. 5 is wound inside the mover 49. A field magnetic flux is generated by the permanent magnet 52 disposed on the stator 50, and a current is applied to the winding 54, so that a thrust F corresponding to Fleming's left-hand rule F = magnetic flux density B × current I × winding length The driving principle for driving the table 66 when L occurs is the same as that of the conventional linear motor.
[0027]
The pressing portion 68 is two columnar members that protrude from the mover 49 in the horizontal direction. The two pressing portions 68 are mounted at positions symmetrical with respect to the movable element 49 of the linear motor. Each pressing portion 68 is inserted between two ball cages 72, respectively. The pressing portion 68, the groove 70, and the ball cage 72 are preferably used by pressing the pressing portion 68 between the ball cages 72 in order to eliminate play in the sliding direction. However, if the squeeze at the time of press-fitting is too large, dents will be formed on the pressing part 68 and the groove part 70 and the ball cage 72 will not move smoothly. It is necessary to use with proper shimeshiro.
[0028]
Next, the operation of the feeder using the linear motor according to the present invention will be described. The table driving member 48 of the linear motor is not directly fixed to the table 66 but is attached to the table 66 via a pressing portion 68 and a ball cage 72. When a current is applied to the winding 54 of the linear motor to generate a thrust, the thrust is transmitted from the pressing portion 68 to the table 66 via the ball cage 72, and drives the table 66 in the sliding direction (the direction of the arrow 64). I do. On the other hand, even if a magnetic attraction force is generated in the linear motor and the movable element 49 is deformed in the direction of the stator 50, the pressing section 68 is deformed in the direction indicated by an arrow 74 perpendicular to the sliding direction, Since the table 66 slides on the ball cage 72 in the direction of the arrow 74, the table 66 is not affected by the deformation due to the magnetic attraction.
[0029]
As described above, in the configuration according to the present embodiment, unlike the feeding device described in JP-A-8-192326 or JP-A-2000-14120 described in the related art, the sliding device can slide in the direction perpendicular to the sliding direction with respect to the table 66. Since the table is driven by pressing the table with the appropriate pressing portion, the magnetic attraction force is not transmitted to the table 66, and the table 66 and the rolling guide 62 are not deformed.
[0030]
However, the bed 60 receives the magnetic attraction force of the linear guide. However, unlike a table that must be reduced in weight to obtain high acceleration performance, a bed such as a machine tool can adopt a structure that obtains much higher rigidity than a table. It can be suppressed to a small level without practical problems.
[0031]
Second embodiment.
Next, a second embodiment of the present invention will be described. The feeder according to the second embodiment differs from the first embodiment in that a slide guide 76 is arranged in the groove 70 of the table 66 instead of the ball cage 72. FIG. 2 is a side view of the groove 70 in which the slide guide 76 is arranged. Also in this case, as in the case where the ball cage 72 is used, the pressing portion 68 slides on the slide guide 76 and slides in the direction of the arrow 74 where the magnetic attraction force is generated, so that the same effect as in the above embodiment can be obtained. The material of the slide guide 76 is excellent in abrasion resistance such as white metal and kelmet, and a metal material having a small coefficient of friction, a phenol resin, a polyamide resin, a polytetraethylene resin, etc. Although it is preferable to use an excellent synthetic resin, the material is not particularly specified, and any material having excellent wear resistance and lubricity can be applied to the present invention, similarly to the above-mentioned materials.
[0032]
The same operation can be performed by a mechanism for sliding the pressing portion 68 even if a cylindrical roller is arranged so as to roll in the direction of the arrow 74 instead of a ball such as the ball cage 72. As described above, the mechanism that does not exert the effect of the magnetic attraction force on the table 66 is not limited to the mechanism described in the above embodiment. However, it is preferable that the pressing portion 68 can be arranged on the table 66 without play. Further, depending on the magnitude of the thrust generated by the linear motor, a plurality of pressing portions 68 may be additionally provided. In FIG. 1, the pressing portion 68 is mounted at a target position with the movable element 49 of the linear motor interposed therebetween. However, the mechanism is not particularly limited. They may be arranged asymmetrically.
[0033]
Third embodiment.
FIG. 3 is a view showing a third embodiment of the present invention, and has a structure using an elastic body 75 instead of the ball cage 72 and the pressing portion 68. Since the elastic body 75 has a long cross-sectional shape shown in FIG. 3 and a long length in the table sliding direction (length in the depth direction in FIG. 3), the rigidity is high in the sliding direction of the table 66 and the magnetic attraction force of the motor, that is, It has a characteristic of low rigidity in the direction of arrow 74. By connecting the elastic body 75 to the mover 49 of the linear motor and the table 66, the deformation of the mover 49 in the direction of the arrow 74 due to the magnetic attraction force of the linear motor is absorbed by the elastic body 75 and is not transmitted to the table 66. The thrust in the sliding direction of the table 66 is transmitted to the table 66 via the elastic body 75. It should be noted that the shape of the elastic body 75 is not limited to the shape shown in FIG. 3. The shape of the elastic body 75 has a high rigidity in the sliding direction of the table 66 and a low rigidity in the magnetic attraction direction of the motor. Applicable.
[0034]
Furthermore, in the present invention, the case of the synchronous linear motor in which the permanent magnet is arranged on the stator side and the winding is arranged on the mover side has been described, but the linear motor having the permanent magnet and the winding on the mover side has been described. There are various types of linear motors, such as a reluctance type that does not use a permanent magnet, and the present invention can be similarly applied to a linear motor that generates a magnetic attractive force. Further, as the rolling guides indicated by 42, 62, and 64, other sliding guides or a combined rolling and sliding guide may be used.
[0035]
【The invention's effect】
As described above, in the linear motor feeder according to the present invention, the movable element is moved in the sliding direction with respect to the table so that the magnetic attraction generated between the movable element and the stator does not affect the table and the guide mechanism. It is arranged so as to transmit only the force and slides in the direction of the magnetic attraction force of the linear motor so as not to transmit the force, eliminating deformation of the table and linear guide due to the magnetic attraction force of the linear motor, It is possible to provide a linear motor feeder that achieves improved acceleration performance and reduced cost by reducing the weight of the table.
[Brief description of the drawings]
FIG. 1 is a front view and a side view showing a linear motor feeder according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a second embodiment of the present invention.
FIG. 3 is a diagram showing a third embodiment of the present invention.
FIG. 4 is a front view and a side view showing a linear motor feeder according to the related art.
FIG. 5 is a sectional view of a linear motor according to a conventional technique in a table sliding direction.
FIG. 6 is a cross-sectional view of a linear motor table feeder according to the prior art disclosed in Japanese Patent Application Laid-Open No. 8-192326.
FIG. 7 is a cross-sectional view of a linear motor table feed device according to the related art disclosed in Japanese Patent Application Laid-Open No. 2000-14120.
[Explanation of symbols]
40, 60 beds, 42, 62, 64 rolling guides, 46, 66 tables, 48 table drive members, 49 movers, 50 stators, 51, 61 protrusions, 52 permanent magnets, 54 windings, 56 field magnetic flux, 67 legs, 68 pressing parts, 70 grooves, 72 ball cage, 75 elastic body, 76 sliding guide.

Claims (4)

A feeder using a linear motor,
A stator having a linear motor, a first guide extending in the feed direction, and a bed having a second guide,
A table supported by the first guide and slidably mounted on the bed,
A movable element of a linear motor supported by the second guide and arranged to face the stator, and a pressing portion that presses the table in a sliding direction and is slidable in a direction perpendicular to the sliding direction. A table driving member having
A feeding device comprising: The feed device according to claim 1, wherein
A feeding device comprising: a ball cage disposed between a pressing portion of the table driving member and the table. The feed device according to claim 1, wherein
A feeding device comprising a sliding guide disposed between a pressing portion of the table driving member and the table. A feeder using a linear motor,
A linear motor stator, a first guide extending in the feed direction, a bed having a second guide,
A table supported by the first guide and slidably mounted on the bed,
A table driving member supported by the second guide and having a linear motor mover disposed opposite to the stator,
A connection member that connects the table drive member and the table, the connection member having high rigidity in a slide direction of the table and low rigidity in a direction perpendicular to the slide direction,
A feeding device comprising:

Images