JP2006054972A - Linear motor for machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear motor for machine tool which is high in positioning accuracy by magnetizing a plurality of permanent magnets after arraying them on both sides of a plate-shaped yoke. <P>SOLUTION: This linear motor 10 for a machine tool comprises a stator 13 where the plurality of permanent magnets 12 in the same form being magnetized in the vertical direction to the face of the yoke 11 are arrayed, at equal intervals so that the direction of the magnetization may be different from adjacent permanent magnets 12, on both sides of the plate-shaped yoke 11, and a pair of moving members 16 where armature coils 14 provided with a plurality of teeth with armature coils 15 wound are counterposed severally to the rows of each permanent magnet 12 provided on both sides of the plate-shaped yoke 11 so that the central axis of each armature coil 15 may be parallel with the direction of the magnetization of each permanent magnet 12. After the plurality of permanent magnets 12 are arrayed on both sides of the plate-shaped yoke 11, the permanent magnets 12 are magnetized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a linear motor for machine tools. In particular, the present invention relates to a linear motor for a machine tool that is used in a driving device in a machine tool such as a cutting device, a milling machine, a machining center, or a laser processing machine, and whose stator is a permanent magnet type.

  Laser processing machines have been widely used as devices for processing semiconductor workpieces and the like. FIG. 7 is a conceptual diagram showing an example of a conventional laser beam machine. According to the illustrated laser beam machine, a table 122 is provided on a frame 121, and a workpiece (not shown) to be machined is placed on the table 122. Further, an X-axis drive device 123 that is movable in the X-axis direction in a coordinate plane parallel to the workpiece surface to be processed is attached above the frame 121. Further, a Y-axis drive device 124 that can move in the Y-axis direction via attachment parts is attached to the drive device 123, and a Z-axis drive device 125 that can move in the Z-axis direction is attached to the Y-axis drive device 124. A torch 126 for emitting laser light is attached to the shaft driving device 125. In FIG. 7, the wiring of the driving device, the control device, and the member that transmits the laser light are omitted.

  In the laser processing machine having such a configuration, the X-axis drive device 123 and the Y-axis drive device 124 are controlled by a control device (not shown), and a desired laser beam from the torch 126 attached to the tip is applied to the workpiece. Cut into shapes. In order to focus the laser beam, the distance between the torch 126 and the workpiece is controlled by the driving device 125 in the Z-axis direction. In the conventional laser beam machine having such a configuration, a drive device constituted by a rotary servo motor and a ball screw has been used.

  However, the above-described laser processing machine using a rotary servo motor has a limit for high-speed processing, and the fast feed speed is about 20 m / min. Furthermore, when the workpiece is longer than 3 m, there is a problem that the machining accuracy is lowered due to the deflection of the ball screw. Therefore, studies have been made to replace the drive unit with a linear motor.

  The linear motor has a stator in which a plurality of permanent magnets magnetized in a direction perpendicular to the surface of the yoke are mounted on a plate-shaped yoke such as an iron plate at equal pitches so that the directions of magnetization are alternately different from each other; The armature core (magnetic core) made of a magnetic material disposed so as to face the permanent magnet array is composed of a mover in which an armature coil is wound. Since a machine tool requires a large thrust, such a linear motor is preferably used. In a linear motor, position control, speed control, and the like are performed by supplying a current suitable for the position to the armature coil. This position is determined on the assumption that the permanent magnets are magnet arrays of equal pitch. . Therefore, if there is a pitch error, it is difficult to perform high-speed and high-accuracy positioning, and the advantages of the linear motor may not be fully utilized. The pitch (also referred to as a magnet pitch) is the sum of the width of the permanent magnet and the distance between the permanent magnets in the moving direction of the mover.

In manufacturing a conventional linear motor, magnetized magnets are arranged in a plate-like yoke. For this reason, due to the influence of the magnetic force or the like, the magnet does not fit in a predetermined position on the plate-like yoke, and it is difficult to stably obtain the magnet row pitch of the stator at regular intervals. As a result, in a machine tool incorporating a linear motor, problems such as misalignment and high-speed and high-precision positioning, which is the final target, have occurred. Furthermore, the conventional linear motor manufacturing method is accompanied by handling of magnetized magnets when assembling each magnetized magnet to the stator yoke, prevention of mistakes in the magnetization direction, and safety when assembling. There are many problems.
Accordingly, an object of the present invention is to solve these problems and provide a linear motor for machine tools with higher positioning accuracy.

  That is, the present invention is a linear motor for machine tools, in which a plurality of identically shaped permanent magnets magnetized in a direction perpendicular to the surface of the yoke on both sides of a plate-like yoke are magnetized with adjacent permanent magnets. The stator is arranged at equal intervals in the moving direction of the mover and the armature core around which the armature coil is wound, and the central axis of the armature coil is parallel to the magnetization direction of the permanent magnet. And a pair of movers arranged opposite to each row of permanent magnets provided on both sides of the plate-like yoke, and the plurality of permanent magnets on both sides of the plate-like yoke. It is characterized by being magnetized after being arranged.

  According to another aspect of the present invention, there is provided a method for manufacturing a stator for a linear motor for machine tools, wherein a plurality of non-magnetized permanent magnets are magnetized at equal intervals on both surfaces of a plate-like yoke. And arranging the arranged permanent magnets in a direction perpendicular to the surface of the yoke and in a direction different from that of the adjacent permanent magnets.

  According to the present invention, magnets in a non-magnetized state are arranged on the yoke, so that the pitch of the magnet rows of the stator is stably evenly spaced, and the characteristics are good and the productivity is high. A linear motor is provided. Further, according to the method of the present invention, a stator for a linear motor for a machine tool is manufactured without handling a magnetized magnet, without a predetermined positional shift due to the influence of the magnetic force, etc., and with no error in the magnetization direction. be able to. Further, the time required for assembling the magnet to the yoke and magnetizing each magnet is greatly reduced, and mass production of the linear motor for machine tools having the above-described characteristics becomes possible.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the drawings, the same members are denoted by the same reference numerals. Note that the present invention is not limited to the scale and number of members shown in the drawings.

  FIG. 1 is a cross-sectional view of a linear motor 10 according to an embodiment of the present invention, cut along a plane parallel to the moving direction of the mover and perpendicular to the permanent magnet fixing surface of the yoke. The linear motor 10 includes a stator 13 composed of a plate-like yoke 11 and a plurality of permanent magnets 12, and a mover 16 composed of an armature core 14 and an armature coil 15.

  In the illustrated stator 13, a plurality of permanent magnets 12 are arranged at the same pitch on one surface of the plate-like yoke 11 along the longitudinal direction of the yoke 11 to form a magnet row 17.

  The plate-like yoke 11 is a plate-like member whose longitudinal direction is the moving direction of the mover. As a material for the plate-like yoke 11, a particularly general magnetic material can be used. Examples thereof include, but are not limited to, low carbon steel and silicon steel plate. Note that the yoke 11 may have either an integral shape or an individual shape. In the case of the divided state, it can be assembled at the stage of assembling as a linear motor to the machine tool.

  The plurality of permanent magnets 12 are plate-like members each having the same shape and dimensions. In the present invention, the permanent magnet 12 is not magnetized before being arranged on the plate-like yoke 11. As a material of the permanent magnet 12, a permanent magnet such as an Nd-based or Sm-based rare earth-based material, a ferrite-based material, an alnico-based material, or the like can be used. The present invention is particularly effective when an Nd—Fe—B magnet that is easily oxidized is used. In particular, a magnet obtained by powder metallurgy or a rapid cooling method is preferably used so as to have a desired composition, and the surface of the permanent magnet 12 may be treated with a surface treatment agent for rust prevention.

  In the stator 13, each permanent magnet 12 is usually fixed to the plate-like yoke 11 via an adhesive or the like. Each permanent magnet 12 is magnetized in a direction perpendicular to the surface to which the magnet of the plate-like yoke 11 is fixed, and the magnetization directions of the adjacent permanent magnets 12 are alternately different. In FIG. 1, the direction of magnetization of each permanent magnet 12 is indicated by an arrow. The magnet pitch can be appropriately determined according to the number of armature core teeth of the mover, the number of poles of the permanent magnet, and the size and shape of the permanent magnet. Further, the permanent magnet 12 is similarly arranged on the other surface of the plate-like yoke 11. At this time, the magnet rows 17 on both surfaces of the yoke 11 face each other so as to overlap each other with the yoke 11 interposed therebetween, and the magnetization directions of the two permanent magnets 12 facing each other are reversed.

  The stator 13 may further include a plate. FIG. 2 schematically shows members constituting a stator including a plate. The plate 18 can be attached in parallel to the magnet row 17 on the surface of the yoke 11 to which the permanent magnet 12 is fixed. The plate 18 can prevent the fixed position of the permanent magnet 12 from shifting in the direction perpendicular to the longitudinal direction of the yoke. In the form shown in FIG. 2, two magnet pressing plates 18 are arranged so as to be in contact with the surface in the width direction of each permanent magnet 12 and sandwich the magnet row 17, and are heat resistant such as screws, bolts, or epoxy resin. It is fastened with resin material.

  The mover 16 is constituted by an armature core 14 having a plurality of teeth around which an armature coil 15 is wound. In the mover 16, a plurality of armature coils 15 are provided, and the central axes of the respective coils 15 are arranged in parallel along the mover moving direction. The armature core 14 can be made of a magnetic material similar to that of the plate-like yoke 11, and a copper wire or the like can be used as the armature coil 15.

  The mover 16 is configured so that the central axis of the plurality of armature coils 15 is perpendicular to the surface of the plate-shaped yoke 11 where the magnet row 17 is fixed, that is, parallel to the magnetization direction of the magnet. It arrange | positions through the space | gap between the row | line | columns 17. FIG. One mover 16 is disposed on each side of the stator 13.

  According to the linear motor 10 having such a configuration, accurate and high-speed positioning becomes possible when used as a moving mechanism of a laser processing machine.

  Next, the linear motor 10 according to the present embodiment will be described from the side of the method for manufacturing the stator 13. In the method for manufacturing the stator 13 of the linear motor 10 according to the present embodiment, a plurality of identically-shaped permanent magnets 12 that are not magnetized are arranged on both surfaces of the plate-like yoke 11 at equal intervals. And magnetizing each permanent magnet 12 in a direction perpendicular to the surface of the yoke 11 and different from the adjacent permanent magnet 12.

  In the arranging step, the non-magnetized permanent magnets 12 are laminated on the plate-like yoke 11 and fixed with an adhesive or the like. At this time, lamination is performed so that the magnet row pitch 7 is stably spaced at equal intervals. The permanent magnet 12 can be positioned by any method such as a spacer method, a groove method, or the like. By using the permanent magnets 12 that are not magnetized, the problem that the pitch of the magnet rows cannot be stably spaced is solved, and the permanent magnets 12 are arranged on the plate-like yoke 11 at equal intervals. Can do.

  After the step of arranging, a step of attaching a plate for holding the magnet to the outside of the magnet row 17 can be performed as necessary. The plate can be attached by being fixed to the plate-like yoke 11 with a screw, a bolt, a heat-resistant resin material such as an epoxy resin, or the like.

  In the magnetizing step, the magnet 13 can be magnetized in the state of the stator 13 in which the permanent magnet 12 not magnetized in the yoke 11 is arranged. The permanent magnets 12 whose magnetization directions are perpendicular to the surface of the plate-like yoke 11 on which the magnet row 17 is fixed and whose magnetization directions are different are arranged alternately along the longitudinal direction of the yoke 11. Magnetize. When the stator 13 having the configuration shown in FIG. 1 is magnetized, it may be magnetized one side at a time or both sides may be magnetized simultaneously.

  In a magnetizer, a desired magnetizing current can be selected using a pulse power source, a high frequency power source or the like. The magnetizing current is preferably 5000 to 20000 A. Magnetization conditions and the like vary depending on the type and size of the magnet and the performance of the magnetizing device. For example, the length and pitch of the magnetizing coil can be changed according to the form of the magnet array, and the magnetizing current can be adjusted by changing the size of the magnetizing coil. Such conditions can be determined by those skilled in the art as needed.

  A linear motor 10 for machine tools of the present invention was produced. The permanent magnet 12 used was an Nd—Fe—B sintered magnet (Shin-Etsu Chemical N48H, Br = 1.35T, iHc = 1273 kA / m). The magnet dimensions were 100 mm, width 18 mm, and thickness 5 mm. The permanent magnet 12 in a non-magnetized state is fixed to the iron yoke 11 (material S50C, dimensions: length 550 mm, width 116 mm, thickness 19 mm). The stator 13 was manufactured by assembling at equal pitches and fixing magnet pressing plates to both ends. FIG. 2 shows a schematic view of members constituting the stator 13 of the linear motor 10 manufactured in the example. The stator 13 is composed of a plate-shaped yoke 11, magnet rows 17 formed on both surfaces thereof, and a magnet pressing plate 18 provided so as to sandwich the magnet rows in parallel with the magnet row 17. FIG. 3 schematically shows the configuration of the stator 13 after the permanent magnets 12 are arranged and fixed on the surface of the yoke 11. The magnet row 17 was sandwiched between two plates 18 fixed by screws, and the displacement of the permanent magnet 12 in the direction perpendicular to the moving direction of the mover was prevented.

  This stator 13 is full at 13000 A using a pulse magnetizer (manufactured by Nichicon, a pulse magnetizing device) having a magnetizing pitch of 20 cm corresponding to four periods of magnet polarity pitch and a magnetizing pitch per one. Magnetized. The total length was magnetized in three steps. The magnetization direction of the magnet was the thickness direction, that is, the direction perpendicular to the magnet fixing surface of the iron yoke 11. A magnetized magnetic circuit (FIG. 3) was incorporated as a stator 13 in a linear motor 10 having the configuration of FIG.

  As a comparative example, magnets magnetized before being arranged on the yoke (magnetization conditions are the same as in the example) are slid while sliding with a squeezing jig, adjusted in position, and directly crimped to the back yoke by the magnet's attractive force. And allowed to cure at room temperature. Along the longitudinal direction of the back yoke, magnets having opposite magnetization directions were alternately assembled at equal pitches, and magnets were similarly assembled on the back surface. Then, a linear motor for machine tools was created by incorporating the same mover as in the example.

  For the linear motors for machine tools of the example and the comparative example, the surface magnetic field distribution in the stator thickness direction 3 mm above the magnet surfaces on the front and back surfaces of the stator 13 is moved in the axial length direction of the stator. And measured. The surface magnetic field measurement results are shown in FIGS. FIG. 4 shows the surface magnetic field distribution of the stator magnetized after being fixed to the yoke. FIG. 5 is a surface magnetic field distribution of a stator formed by rubbing a conventional magnetized magnet. Even with a stator including magnets magnetized after arrangement, a sufficiently stable magnetic field strength was obtained and production was possible. Further, in the machine tool linear motor 10 of the example, the magnet row pitch of the stator could be stably obtained at equal intervals as compared with the comparative example.

  The result of measuring the cogging torque of this linear motor is shown in FIG. The cogging force of the linear motor is a force that periodically acts in the traveling direction or the opposite direction when the mover moves, and the cycle is the pitch of the magnet. The sum of the magnetic attractive forces generated between the magnet and each tooth of the armature core is the cogging force, and the magnetic attractive forces generated by the teeth inside the armature core cancel each other, but are generated at both ends of the armature. Since the magnetic attraction force does not cancel well, it appears as a cogging force of the magnet pitch period.

  The measurement is performed by connecting the manufactured linear motor and the evaluation linear motor via a 1 kN load cell, moving the evaluation linear motor without passing an electric current through the manufactured linear motor, and stopping at every measurement pitch of 1 mm. And the thrust (indicated value of the load cell) were measured.

  FIG. 6 shows the cogging torque measurement results of the linear motors manufactured in the example and the comparative example. As a result, it was possible to suppress the pulsation of the cogging waveform due to errors such as the magnet pitch that occurred in the comparative example. Further, since the (maximum value)-(minimum value) of the cogging could be suppressed to 19N in the example of the comparative example 24N, the position and speed could be easily controlled, and high-speed positioning as a linear motor became possible.

  The present invention can be applied to a drive device of a machine tool such as a cutting device, a milling machine, a machining center, or a laser processing machine.

It is a figure explaining the linear motor which concerns on embodiment of this invention. It is a figure explaining the components which comprise a stator. It is a general-view figure of a stator magnetic circuit. It is a figure explaining the surface magnetic field distribution on 3 mm of magnet surfaces in the stator axial length direction of the stator magnetic circuit manufactured by the Example. It is a figure explaining the surface magnetic field distribution on 3 mm of magnet surfaces in the stator axial length direction of the stator magnetic circuit manufactured by the comparative example. It is a figure showing the measurement result of cogging torque. It is sectional drawing explaining a laser beam machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Linear motor 11 Plate-shaped yoke 12 Permanent magnet 13 Stator 14 Armature core 15 Armature coil 16 Movable element 17 Magnet row 18 Plate 121 Frame 122 Table 123 X-axis direction drive device 124 Y-axis direction drive device 125 Z-axis direction drive Device 126 Torch

Claims (3)

A plurality of identically shaped permanent magnets magnetized in a direction perpendicular to the surface of the yoke on both surfaces of the plate-like yoke are arranged at equal intervals in the moving direction of the mover so that the direction of magnetization differs from that of the adjacent permanent magnets. An array of stators,
Armature cores around which armature coils are wound are arranged in rows of permanent magnets provided on both surfaces of the plate-shaped yoke so that the central axis of the armature coils is parallel to the magnetization direction of the permanent magnets. A linear motor for a machine tool comprising a pair of movers arranged to face each other,
A linear motor for machine tools, wherein the plurality of permanent magnets are magnetized after being arranged on both surfaces of the plate-like yoke. A step of arranging a plurality of identically magnetized permanent magnets on both surfaces of the plate-like yoke at equal intervals in the moving direction of the mover;
A method of manufacturing a stator of a linear motor for machine tools, comprising magnetizing each arrayed permanent magnet in a direction perpendicular to the surface of the yoke and different from an adjacent permanent magnet. A laser processing machine using the linear motor according to claim 1 for a three-dimensional moving mechanism.

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