JP3828623B2 - Moving coil linear motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a movable coil type linear motor including an armature coil (for example, a multiphase coil) which is movable along a longitudinal direction of a cover provided on a fixed field permanent magnet.
[0002]
[Prior art]
Conventionally, it has a fixed field permanent magnet and an armature coil movably installed in a magnetic gap formed by the permanent magnet, and supplies a driving current to the armature coil. 2. Description of the Related Art A moving coil type linear motor configured to generate thrust and move along the longitudinal direction of the permanent magnet is known.
[0003]
FIG. 5 is a cross-sectional view of a main part showing a conventional moving coil linear motor.
In the conventional moving coil type linear motor 100 shown in FIG. 5, a center yoke 2 and side yokes 3 and 3 are erected on a base 1, and a pair of center yoke 2 and side yoke 3 are opposed to each other on a side surface. Permanent magnets 4, 4 are arranged to form a magnetic gap 15. The pair of permanent magnets 4, 4 are arranged in a length corresponding to the stroke of the movable element 16 of the movable coil type linear motor 100 in the direction perpendicular to the paper surface, and the pair of permanent magnets 4, 4 and the side yoke 3. And the center yoke 2 as one set of stators to form a total of two sets of stators. In addition, coil frames 18 and 18 are attached to the lower part of the carriage 7 constituting the movable element 16. The coil frame 18 has flat three-phase coils 6 and 6 (for example, Japanese Patent Publication No. 8-13184) on both side surfaces of the magnetic gap 15 facing the pair of permanent magnets 4 and 4 via a substrate (not shown). And the movable element 16 is switched by switching the drive current flowing in each of the three-phase coils in accordance with a desired thrust pattern using a magnetic pole detection means and / or position detection means (not shown). A predetermined thrust is obtained so that the magnetic gap 15 can be moved in the direction perpendicular to the paper surface.
[0004]
FIG. 6 shows a conventional example of a cross-sectional view of the stator shown in FIG.
The stator 63 of FIG. 6 is arranged on the center yoke 2 and the side yoke 3 with a plurality of rectangular parallelepiped permanent magnets 4c having different magnetic poles adjacent to each other and different magnetic poles opposed via the magnetic gap 15a. is there.
In this stator 63, for example, the mover in the magnetic gap 15a when the width (w ′) in the direction perpendicular to the paper surface of the permanent magnet 4c is 50 mm, the length (l ′) is 30 mm, and the thickness (tm1) is 10 mm. When the magnetic flux density distribution in 16 stroke directions was measured, the result shown in FIG. 10C was obtained. The vertical axis in FIG. 10 is the magnetic flux density (G), and the horizontal axis is the position (mm) corresponding to the stroke of the mover 16. An ideal magnetic gap magnetic flux density distribution for suppressing a torque ripple and maintaining a good thrust linearity as a moving coil type linear motor is shown, for example, by a sine wave curve (b) in FIG. However, (c) in FIG. 10 is greatly deviated from the ideal (b) in FIG. 10, and the configuration of the stator 63 has a problem that torque ripple increases and thrust linearity deteriorates.
The reason why (c) in FIG. 10 greatly deviates from the ideal (b) in FIG. 10 is that the permanent magnets 4c adjacent to each other without reaching the three-phase flat coils 6 and 6 among the lines of magnetic force generated from the permanent magnet 4c. , 4c has a large amount of reactive magnetic flux (f5) that is short-circuited.
[0005]
In order to solve the problem of torque ripple, a moving coil linear motor (for example, Japanese Patent Laid-Open No. 3-222670) in which a permanent magnet formed in a substantially trapezoidal shape is provided is known.
Further, there is a moving coil type linear motor having the stator shown in FIG.
[0006]
FIG. 7 shows another conventional example of a cross-sectional view of the stator shown in FIG. In the stator 64 of FIG. 7, chamfered portions 9 and 9 are formed on both edges of the permanent magnet 4d on the magnetic gap 15b side to form a substantially trapezoidal cross section, and a plurality of them are adjacent along the longitudinal direction of the cross section. The magnetic poles are different from each other, and the different magnetic poles are arranged to face each other via the magnetic gap 15b. A fixing jig 8 (made of nonmagnetic material) arranged between the permanent magnets 4d and 4d so as to be engaged with the chamfered portion 9 and the upright portion 19 of the permanent magnet 4d is a screw 10 (made of nonmagnetic material). It is concluded with.
In this stator 64, for example, the width (w2) in the direction perpendicular to the paper surface of the permanent magnet 4d is 50 mm, the length (l2) is 30 mm, the thickness (t1) of the chamfered portion 9 is 3.5 mm, and the upright portion 19 When the thickness (t2) is 6.5 mm and the length (l3) of the portion along the magnetic gap 15b is 6 mm, the magnetic flux density distribution in the stroke direction of the mover 16 in the magnetic gap 15b is ideal in FIG. It is known that (a) of FIG. 10 approximated to (b) is obtained.
[0007]
However, in the configuration of FIG. 7, a permanent magnet having a complicated shape is used, so that the cost of the permanent magnet is high and a nonmagnetic member such as a fixing jig 8 or a screw 10 is further required. Since the child structure is complicated and the number of parts increases, there is a problem that an inexpensive moving coil linear motor cannot be provided.
[0008]
Furthermore, in the moving coil type linear motor having the stators shown in FIGS. 6 and 7, the permanent magnet is provided in direct contact with the magnetic gap, so that, for example, during periodic inspections, parts replacement at the time of failure or high speed running, etc. May cause damage to the permanent magnet. In order to prevent such damage to the permanent magnet, a method of providing a cover on the side where the permanent magnet is in contact with the magnetic gap has been proposed as shown in FIGS.
[0009]
The stator 65 of FIG. 8 has the same configuration as that of FIG. 6 except that the nonmagnetic cover 30 is provided on the magnetic gap 15c side.
9 has the same configuration as that of FIG. 7 except that the nonmagnetic cover 35 is provided on the magnetic gap 15d side.
[0010]
However, when comparing the thickness of the magnetic gap in the conventional moving coil type linear motor of FIGS. 6 to 9 with a constant thickness, the magnetic gap in FIG. 8 is equal to the thickness (t30) of the nonmagnetic cover 30 compared to FIG. Since the distance (Lg3m) between the permanent magnets 4a and 4a facing each other via 15c is increased, the magnetic flux density distribution level of the magnetic gap 15c is lowered, resulting in a decrease in thrust of the moving coil linear motor. . Here, the thickness of the magnetic gap 15a in FIG. 6 is (Lg1), the thickness of the magnetic gap 15c in FIG. 8 is (Lg3), and the substantial thickness of the magnetic gap 15c is (Lg3m).
The problem that the magnetic field strength of the magnetic air gap decreases due to the installation of the nonmagnetic cover and the thrust of the moving coil linear motor decreases similarly exists in FIG. 9 with respect to FIG. Here, the thickness of the magnetic air gap 15b in FIG. 7 is (Lg2), the thickness of the magnetic air gap 15d in FIG. 9 is (Lg4), and the substantial thickness of the magnetic air gap 15d is (Lg4m: the distance between the opposing permanent magnets 4b and 4b). It is.
[0011]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a movable coil type linear motor that is of a cover-attached type, can suppress torque ripples to a very low level, can improve the thrust linearity, and can obtain a large thrust.
[0012]
[Means for Solving the Problems]
Moving-coil linear motor of the present invention which achieves the above-mentioned problems, moves a plurality of permanent magnets forming a magnetic gap, and a cover provided on the surface of the permanent magnet, the inside magnetic gap along the cover armature A moving coil type linear motor comprising a coil,
The cover is formed using a material that coexist with the ferromagnetic portion and the non-magnetic portion,
The non-magnetic part is provided at a position to suppress the short-circuit magnetic flux and is composed of a melt-solidified structure and a heating / cooling structure,
The material is magnetic stainless steel or high manganese steel,
The total occupied area of precipitated carbide particles in the melt-solidified structure is smaller than the total occupied area of precipitated carbide particles in the heating and cooling structure .
According to the present invention, since a cover in which a ferromagnetic portion and a nonmagnetic portion coexist can be formed with a single member and the nonmagnetic portion is disposed at a position to suppress the short-circuit magnetic flux, the magnetic gap can be substantially reduced while suppressing the short-circuit magnetic flux. As a result, it is possible to provide a moving coil type linear motor having excellent thrust linearity and large thrust. In addition, by providing the cover, it is possible to provide a moving coil linear motor that is not easily damaged even when an impact is applied and that has excellent durability.
[0014]
Further, when the non-magnetic portion of the cover has a melted and solidified structure of 30% by volume or more, even if the moving coil linear motor of the present invention is exposed to an extremely low temperature atmosphere up to −60 ° C., the non-covering portion of the cover Since the magnetic portion is present stably, good thrust linearity and large thrust in an extremely low temperature range up to −60 ° C. can be maintained.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
[0017]
FIG. 4 is a cross-sectional view of an essential part showing an embodiment of the moving coil linear motor of the present invention. The same reference numerals are given to the same components as those in FIG.
In the moving coil type linear motor 50 of the present invention shown in FIG. 4, a cover 11 in which a ferromagnetic portion and a nonmagnetic portion coexist is provided on opposite sides of a pair of permanent magnets 4, 4.
[0018]
Figure 1 shows a reference example of the A-A direction arrow sectional view of a stator of FIG. 4, the same components as those of the FIG 8 are denoted by the same reference numerals.
In the stator 60 of FIG. 1, the nonmagnetic part of the cover 11 is constituted by a heating / cooling part 11bh, which is arranged just above the boundary between adjacent rectangular parallelepiped permanent magnets 4a, 4a and schematically shown as a short-circuit magnetic flux ( f2) is suppressed, and the effective magnetic flux (f1) contributing to the formation of the magnetic gap 5 is increased. This effective magnetic flux (f1) is detected by magnetic detecting means (not shown) provided in the vicinity of the three-phase flat coil as the mover 16 travels, and the energization timing of the drive current to be supplied to the three-phase flat coil is adjusted. It is like that. Further, since the length (m) of the ferromagnetic portion 11a of the cover 11 is made smaller than the length (l) of the permanent magnet 4a, the effective magnetic flux (f1) is increased and the short-circuit magnetic flux (f2) is decreased. It is possible.
The cover 11 is an alloy material in which a ferromagnetic portion and a non-magnetic portion can coexist; for example, local heating described later using one or more of ferritic and martensitic magnetic stainless steel, high manganese steel, and the like. Using a cooling means (corresponding to a reference example) or a local heating and melting and solidifying means (corresponding to an example described later) , it can be manufactured through appropriate machining as required. The cover 11 can be formed of a single piece of part, and the cover 11 may be divided into a plurality of units in which the ferromagnetic portion 11a and the nonmagnetic portion 11bh coexist as necessary. By providing this cover 11, the substantial thickness of the magnetic gap 5 is not the distance (Lgm) between the pair of permanent magnets 4a and 4a opposed via the magnetic gap 5, but the distance between the pair of ferromagnetic portions 11a and 11a. (Lg). That is, the magnetic field lines generated from the N pole of the permanent magnet 4a sequentially form a closed loop (effective magnetic flux f1) that returns to the S pole of the ferromagnetic portion 11a, the magnetic gap 5, the ferromagnetic portion 11a, and the permanent magnet 4a of the cover 11. Therefore, on the magnetic circuit, it is substantially equivalent to the increase in the thickness of the permanent magnet 4a from (tm) to (t = tm + tc). Therefore, even if the cover 11 is arranged, the magnetic field strength of the magnetic gap 5 is almost the same as when a pair of permanent magnets 4a, 4a having a thickness (t) are arranged opposite to each other, and the level of the magnetic flux density distribution of the magnetic gap 5 And a large thrust can be applied to the mover 16. At the same time, since the nonmagnetic portion 11bh suppresses the short-circuit magnetic flux f2 that is a cause of the non-sinusoidal component of the magnetic flux density distribution in the magnetic gap 5, it is possible to impart good thrust linearity to the mover 16.
[0019]
( Reference Example 1 )
As a material for forming the cover 11, a ferritic stainless steel material having a composition comprising 0.6% C-13% Cr-residual Fe and unavoidable impurities in weight% is used, and the entire material is made to have excellent ferromagnetic properties. Therefore, appropriate magnetic annealing was performed to obtain a material having excellent ferromagnetic properties of maximum saturation magnetic flux density Bs = 1.4T and coercive force Hc = 10 Oe at 20 ° C. as shown in the BH curve of FIG. .
Next, after machining the material to the approximate dimensions of the cover 11, the portion corresponding to the non-magnetic portion 11bh is irradiated with a CO ₂ laser so that the portion to be demagnetized exceeds the austenite transformation temperature of the material. Then, after heating to a temperature lower than the melting point (for example, 1200 ° C.), cooling was performed to form the ferromagnetic portion 11a having a ferrite structure and the nonmagnetic portion 11bh having an austenite structure. Thereafter, finishing was performed as necessary to finish the final dimensions of the cover 11.
When the BH curve at 20 ° C. of this nonmagnetic part 11bh was measured, the BH characteristic of FIG. 12 was obtained. From FIG. 12, the relative magnetic permeability μs at 20 ° C. of this nonmagnetic part 11bh was about 1.1, and the nonmagnetic characteristic of μs ≦ 2 was secured. This value of μs = 1.1 is a very excellent nonmagnetic property that is almost equivalent to air. Further, the ferromagnetic portion 11a of the cover 11 had the ferromagnetic characteristics shown in FIG.
Next, the results of evaluating the stability of the nonmagnetic portion 11bh in the extremely low temperature range will be described. First, the cover 11 was immersed in a liquid methanol refrigerant adjusted to −10 ° C. to −60 ° C. by adding dry ice, and the temperature at which the austenite phase of the nonmagnetic portion 11bh was transformed into a ferrite phase was examined. The time of immersion in the refrigerant was 30 minutes, and then returned to room temperature of 20 ° C. The results of identifying the crystal structure by X-ray diffraction are shown in Table 1.
[0020]
[Table 1]
A: Austenite phase, F: Ferrite phase From Table 1, it was found that the nonmagnetic portion 11bh of Reference Example 1 was stably present up to -40 ° C without transformation into a ferrite phase. Therefore, the moving coil type linear motor of the reference example equipped with the cover 11 of the reference example 1 can be used for applications up to −40 ° C.
Further, in the stator 60 of FIG. 1 described above, a rectangular parallelepiped block (Hitachi Metals Co., Ltd.) having a width (w) in the direction perpendicular to the paper surface of the permanent magnet 4a of 50 mm, a length (l) of 30 mm, and a thickness (tm) of 9 mm. ) Made of Nd—Fe—B anisotropic sintered magnet: HS37BH), and the magnetic flux density distribution in the stroke direction of the mover 16 in the magnetic gap 5 was measured when the thickness (tc) of the cover 11 was 1 mm. However, the curve (d) in FIG. 10 very close to the ideal sine wave curve (FIG. 10 (b)) was obtained, and it was found that the linearity of the thrust was good.
[0021]
FIG. 2 shows an embodiment of the cross-sectional view of the stator of FIG. 4 according to the present invention taken along the line AA, and the same components as those of FIG. 1 are given the same reference numerals.
The cover 11 ′ in FIG. 2 includes a ferromagnetic portion 11a, and a nonmagnetic portion 11b having a melting and solidifying portion 11bm and a heating / cooling portion 11bh. The melted and solidified portion 11bm is arranged immediately above the boundary between the permanent magnets 4a and 4a to suppress the leakage magnetic flux (f2 ′).
( Example 1 )
A part corresponding to the non-magnetic part 11b is formed by performing the same magnetic annealing using the same material as the reference example 1 as a material for forming the cover 11 ', and then machining the cover 11' into a substantially dimensional shape. Is heated to a temperature of 10 ° C. just above the melting point of the material using a CO ₂ laser, and is locally melted and then cooled and solidified to transform the portion corresponding to the nonmagnetic portion 11b from a ferrite structure to a nonmagnetic austenite structure. It was. Then, finishing was performed as necessary to finish the cover 11 ′ in a dimensional shape. The structure of the non-magnetic part 11b is composed of 70% by volume of the molten and solidified structure 11bm and 30% by volume of the heating / cooling part 11bh.
When the BH curves at 20 ° C. of the ferromagnetic part 11a and the nonmagnetic part 11b of Example 1 were measured, the ferromagnetic part 11a had the same ferromagnetic characteristics as in FIG. 11, and the nonmagnetic part 11b The nonmagnetic characteristics were the same as in FIG.
Next, when the stability of the nonmagnetic portion 11b of Example 1 in the extremely low temperature range was evaluated in the same manner as in Reference Example 1 , the results shown in Table 1 were obtained.
From Table 1, the local melt-solidified part 11bm of Example 1 existed stably without transforming into a ferrite phase even at -60 ° C. Therefore, the movable coil type linear motor of the present invention to which this cover 11 ′ is attached has a large thrust up to −60 ° C. and a linearity of the thrust.
[0022]
In the first embodiment, the case where the abundance ratio of the melted and solidified part 11bm in the nonmagnetic part 11b is 70% by volume is described. However, if the abundance ratio of the melted and solidified part 11bm is 30% by volume or more, the movable coil of the present invention is used. As a type linear motor, it is easy to provide thrust and linearity of thrust that can be practically used in an extremely low temperature range up to −60 ° C.
[0023]
Good existence stability up to −60 ° C. of the melt-solidified portion 11bm has been inferred as follows by the present inventors' microanalysis.
The result of observing the microstructure of the cross sections of the nonmagnetic portions 11bm and 11bh with an electron microscope is shown in the structure photograph of FIG.
In the melt-solidified part 11bm of Example 1 shown in FIG. 13 (a), the number of precipitated carbides is small, but in the heating / cooling part 11bh of Reference Example 1 shown in FIG. 13 (b), the number of precipitated carbide particles is small. Very many. In comparison with FIG. 13 (b), it was found that the total occupied area of the precipitated carbide particles of FIG. 13 (a) was reduced to about 1/40. For this reason, the precipitated carbide cannot be re-dissolved in the parent phase simply by heating the local part above the austenite transformation temperature by the above local heating and cooling treatment, but the precipitated carbide is obtained by performing the above local heating melt solidification treatment. Is re-dissolved in the mother phase, and the effective carbon content of the mother phase portion is increased by the re-dissolution, so that the existence stability of the melt-solidified portion 11bm (austenite phase) is further increased to -60 ° C. It is thought that it was able to exist stably.
[0024]
FIG. 3 is a cross-sectional view of an essential part showing another aspect of the stator attached to the moving coil linear motor of the reference example . 3, the same components as those in FIG. 1 are denoted by the same reference numerals.
In the stator 62 of FIG. 3, a permanent magnet 4a is stuck on the center yoke 2 on the one side through the magnetic air gap 5 ″ in the same manner as in FIG. 1, and the permanent magnet 4a is opposed to the magnetic air gap 5 ″. A cover 11 is provided. Further, a ferromagnetic side yoke 3 (for example, made of SS400) is disposed on the side facing the cover 11 through the magnetic gap 5 ″. According to the configuration of the stator 62, the magnetic flux density distribution level in the magnetic gap 5 '' tends to be slightly lower than that in FIGS. In addition, since the amount of expensive permanent magnets used is reduced, it is possible to provide a movable coil type linear motor with good thrust linearity and low cost.
[0025]
Next, when the cover 11 of Reference Example 1 is arranged on the linear motor 50 ( Reference Example 2 ) and when the cover 11 ′ of Example 1 is arranged ( Example 2 ), the linear motor starts to be driven at 20 ° C. 6 shows the maximum thrust value and torque ripple measured 5 minutes after the test, and the impact test results evaluated under the following conditions. In Table 2, the stator 63 of FIG. When the stator 64 of FIG. 7 is arranged as the comparative example 2 in the linear motor 100, when the stator 65 of FIG. 8 is arranged as the comparative example 3 in the linear motor 50. 9, when the stator 66 of FIG. 9 is arranged in the linear motor 50, the maximum thrust value, torque ripple, and torque ripple evaluated in the same manner as in Reference Example 2 and Example 2, respectively. The impact test results are also shown. Here, at the time of the evaluation, an Nd—Fe—B anisotropic sintered magnet (HS37BH) manufactured by Hitachi Metals, Ltd. is disposed on each stator. Moreover, the maximum value of the thrust in Table 2 is displayed relative to the value of Reference Example 2 as 100%. Further, a small torque ripple means that the thrust linearity is good, and a large torque ripple means that the thrust linearity is poor. Further, the impact test is an examination of the presence or absence of cracks or chipping of the permanent magnets that are disposed by dropping each of the above stators onto a SUS304 stainless steel plate from a height of 1 m.
[0026]
[Table 2]
[0027]
From Table 2, it was found that, in comparison with the comparative examples, those of Reference Example 2 and Example 2 had a large thrust, a small torque ripple, and excellent impact resistance.
[0028]
FIG. 14 is a cross-sectional view of a main part showing still another aspect of the stator in the moving coil type linear motor of the reference example , and the same components as those in FIG. In the stator 67 of FIG. 14, the cover 21 includes a plurality of ferromagnetic members 21 a (for example, made of SS41) attached immediately above each magnetic pole part and a plurality of nonmagnetic members 21 b (attached immediately above each magnetic pole boundary). For example, SUS304.) According to this configuration, there is an advantage that the cover 21 can be formed using a general-purpose ferromagnetic material and a non-magnetic material. In addition, since the substantial thickness of the magnetic gap 5e can be set to (Lg5) as in FIG. 1, the effective magnetic flux (f3) is increased to increase the large thrust and the short-circuit magnetic flux (f4) is suppressed to a small value to improve the thrust linearity. Can be.
[0029]
In the above embodiment, a case where a three-phase flat coil having a special structure is used as the armature coil is described, but other general-purpose three-phase coils, two-phase coils, and the like can be used as appropriate. In the above aspect, a plurality of rectangular parallelepiped permanent magnets are connected to form a field permanent magnet. Instead, a single long rectangular parallelepiped permanent magnet is used, and appropriate magnetizing means described above. Similarly to the embodiment, a multi-pole may be formed to form a magnetic gap.
In addition, the shape of the permanent magnet used in the present invention is not limited to a rectangular parallelepiped, and other shapes (for example, a trapezoidal shape, a ring shape, a fan shape, etc.) capable of forming a magnetic gap can be used.
Moreover, although the moving coil type | mold linear motor which has two magnetic space | gap was described in the said aspect, it is good also as one or 3 or more magnetic space | gap.
In the above embodiment, laser heating is used as the local heating / cooling means and the local heating / melting / solidifying means. Instead, other local heating means (for example, plasma heating, high-frequency heating, contact heating of a high-temperature heating body, etc.) are used. Of course, can be applied as appropriate.
[0030]
【The invention's effect】
The present invention can achieve the following excellent effects.
(1) A movable coil linear motor with a cover, which has the same magnetic gap thickness as a conventional movable coil linear motor without a cover, which is equivalent to a conventional movable coil linear motor without a cover. It is easy to obtain a large thrust.
(2) A good thrust linearity can be obtained together with a large thrust.
(3) A moving coil linear motor having excellent impact resistance can be provided.
(4) When obtaining a magnetic flux density distribution very close to a sine wave, the cover and the permanent magnet can be simplified in shape and the number of parts of the stator can be reduced, so that an inexpensive moving coil linear motor can be provided.
(5) The existence stability of the non-magnetic part of the cover in the extremely low temperature range is greatly improved, which greatly contributes to the expansion of the application of the moving coil linear motor in the extremely low temperature range.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part showing an aspect of a stator in a linear motor of a reference example .
FIG. 2 is a cross-sectional view of a main part showing one aspect of a stator in the linear motor of the present invention.
FIG. 3 is a cross-sectional view of an essential part showing another aspect of the stator in the moving coil linear motor of the reference example .
FIG. 4 is a cross-sectional view of a main part showing one embodiment of a moving coil linear motor of the present invention.
FIG. 5 is a cross-sectional view of a main part showing a conventional moving coil linear motor.
FIG. 6 is a cross-sectional view of a main part showing a stator of a conventional moving coil linear motor.
FIG. 7 is a cross-sectional view of a main part showing a stator of a conventional moving coil linear motor.
FIG. 8 is a cross-sectional view of a main part showing a stator of a conventional moving coil linear motor.
FIG. 9 is a cross-sectional view of a main part showing a stator of a conventional moving coil linear motor.
FIG. 10 is a diagram showing a magnetic flux density distribution in a stroke direction in a magnetic gap.
FIG. 11 is a diagram showing a BH curve of a ferromagnetic portion of a cover.
FIG. 12 is a diagram showing a BH curve of a nonmagnetic part of a cover.
FIG. 13 is a photomicrograph of the melt-solidified part (a) and the heating / cooling part (b) in relation to the heat-transforming part of the present invention.
FIG. 14 is a cross-sectional view of a main part showing still another aspect of the stator in the moving coil linear motor of the reference example .

Claims (2)

A movable coil type linear motor comprising a plurality of permanent magnets having magnetic gaps, a cover provided on the surface of the permanent magnets , and an armature coil that moves in the magnetic gap along the cover,
The cover is formed using a material that coexist with the ferromagnetic portion and the non-magnetic portion,
The non-magnetic part is provided at a position to suppress the short-circuit magnetic flux and is composed of a melt-solidified structure and a heating / cooling structure,
The material is magnetic stainless steel or high manganese steel,
The moving coil type linear motor characterized in that the total occupied area of precipitated carbide particles in the molten and solidified structure is smaller than the total occupied area of precipitated carbide particles in the heating and cooling structure .   The moving coil linear motor according to claim 1, wherein the nonmagnetic portion has a melt-solidified structure of 30% by volume or more.