JP3841766B2 - VCM yoke manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing method of a VCM yoke used in a disk storage device or the like.
[0002]
[Prior art]
Conventionally, a VCM (voice coil motor) type linear motor is used as an actuator for a disk medium such as a magneto-optical disk device (MO). This actuator moves the moving member so as to draw a linear trajectory together with a coil wound movably around the VCM yoke. As shown in FIG. 7, the VCM yoke is obtained by inserting a yoke core 70 made of a ferromagnetic material such as soft iron having a rectangular cross section into a short ring 72 formed of a conductive material such as copper in the shape of a square cylinder. It is.
[0003]
The actuator is configured such that a movable coil body 74, in which a coil is wound in a rectangular tube shape, is fitted into the VCM yoke at a predetermined interval and is movable in the longitudinal direction. Then, a head is attached so as to interlock with the movable coil body 74, and a linearly formed magnet 76 is disposed along the longitudinal direction of the VCM yoke. Both sides of the VCM yoke are fixed to a side yoke 78 formed of pure iron. Here, when an electric signal is sent to the movable coil body 74, a driving force is applied to the movable coil body 74 according to Fleming's law, and the movable coil body 74 moves in the longitudinal direction of the VCM yoke to operate the head. Let
[0004]
Conventionally, for example, a yoke for VCM disclosed in Patent Document 1 is disclosed. This consists of a center yoke having curved surfaces with different bending angles at the upper and lower ends on both sides in the short direction of the yoke, and a short ring that is hollow in cross section and has a rectangular shape on the side, and into which the center yoke is press-fitted. Thus, an even contact surface and an uneven contact surface are formed between the center yoke and the short ring to improve the adhesion between the center yoke and the short ring.
[0005]
[Patent Document 1]
JP 2002-51522 A [Patent Document 2]
JP-A-6-237565 [Patent Document 3]
Japanese Utility Model Publication No. 6-44386 [0006]
[Problems to be solved by the invention]
The VCM yoke is easy to press-fit the center yoke into the short ring due to the difference in contact pressure between the center yoke and the short ring. Force is generated. For this reason, the degree of adhesion between the center yoke and the short ring in the direction intersecting with this is not constant, and there is a concern that a slight gap may occur in the vicinity of the corner portion, and the holding power of the center yoke is reduced. There is. In general, the gap between the center yoke and the short ring also causes resonance sound during use. In addition, there is a need for a technique for obtaining a product with good accuracy and good quality for the manufacturing method of the VCM yoke.
[0007]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a method for manufacturing a VCM yoke that has good accuracy and quality and is easy to manufacture.
[0008]
[Means for Solving the Problems]
In order to solve the above technical problems, the VCM yoke manufacturing method according to the present invention obtains a yoke core made of a long magnetic material by stamping as shown in FIGS. A step of imposing the bottom corners on the long side of the yoke core, a part of the yoke core is inserted into a conductive pipe having a rectangular cross section, and the yoke core is pressed by pressing. An insertion press-fitting step for inserting the pipe and press-fitting the pipe into a state in which the tip protrudes from the tip of the pipe.
[0009]
In the method of manufacturing a yoke for a VCM according to the present invention, the insertion press-fitting step can be performed by inserting a part of the yoke core into the pipe and inserting the pipe with the yoke core into which the pipe is inserted. A step of inserting the tip of the pipe to the step, and press fitting the yoke core into a jig having a hole, a step where the tip of the pipe abuts, and a hole into which only the yoke core can be inserted. Then, the yoke core has a press-fitting step in which the pipe passes through the pipe, and a tip portion of the yoke core passes through the pipe and enters the hole.
[0010]
In the VCM yoke manufacturing method according to the present invention, the jig includes a first jig having a through hole into which the pipe with the yoke core can be inserted, and a cross section smaller than the through hole. And a second jig having a hole with a predetermined depth in which the pipe contacts and only the yoke core can enter.
[0011]
In the method for manufacturing a yoke for a VCM according to the present invention, in the imposing step, the yoke core obtained by punching is formed with a flat bottom surface portion and a slope portion between the bottom surface portion and the top surface portion. Using a lower mold with a recess, place the lower corner on the long side of the yoke core in the middle of the slope and press the upper mold with the flat bottom surface from above the yoke core. Then, imposition is performed on the lower corner portion.
[0012]
In the method of manufacturing a yoke for VCM according to the present invention, side portions capable of closely fitting the yoke core are provided on both sides of the recess of the lower mold, and the yoke core is held and fixed between the side surfaces. And pressing the upper mold.
[0013]
In the method for manufacturing a yoke for VCM according to the present invention, when the yoke core is press-fitted into the pipe, the upper, lower, left, and right surfaces of the yoke core are sized so as to be in contact with each surface of the corresponding pipe evenly. Is defined.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments according to the present invention will be described below with reference to the drawings.
The manufacturing process of the VCM yoke 2 according to this embodiment is roughly divided into a process of obtaining a prototype of the yoke core 4 by stamping, a process of imposing the yoke core 4, and a short of the yoke core 4. There is an insertion press-fitting process into the ring 6.
[0015]
As shown in FIG. 1, the VCM yoke 2 includes a yoke core 4 made of a ferromagnetic material such as soft iron (SPCC or the like) and a short ring 6 made of a conductive material such as copper.
[0016]
In the stamping step of the press work, a plate-shaped steel material (SPCC) is punched out by pressing to obtain a yoke core prototype. This plate-shaped steel material is sent to a press machine by hand etc., and a predetermined interval is maintained by a guide pin, and a prototype of the yoke core is continuously punched out.
[0017]
As shown in FIG. 2 (1), the yoke core 4 has a rounded upper corner due to the punching, and the lower corner 44 of the yoke core 4 is squared. A burr 10 is formed. Next, chamfering (chamfering) 12 is performed on the lower corner portion 44 of the yoke core 4 as shown in the figure (2), and burrs generated by the chamfering as shown in the figure (3). Is finished to a smooth surface 14.
[0018]
In the imposition process, as shown in FIG. 3, the prototype of the yoke core 4 that freely falls on the slope is formed in order using a press. The press has a lower mold 20 and an upper mold 22, and a recess 24 is formed on the upper surface of the lower mold 20. The concave portion 24 is provided with a flat bottom surface portion 26 and slopes 28 inclined on a range of 30 ° to 60 ° (preferably 45 °) on both sides of the bottom surface portion 26. A flat lower surface portion 30 is formed on the upper mold 22.
[0019]
The yoke core 4 is impressed by the inclined surface portion 28 of the concave portion 24 of the lower mold 20, and the upper surface portion 40 of the yoke core 4 is formed flat by the lower surface portion 30 of the upper mold 22. In this imposition process, when the yoke core 4 is placed on the lower mold 20 as shown in FIG. 3B, the lower corners 44 of the yoke core 4 are inclined surfaces 28 of the lower mold 20, respectively. It is put in the state located in the upper part vicinity of.
[0020]
Here, the yoke core 4 is pressed using the press machine. By pressing the upper die 22, the yoke core 4 is pushed down to the bottom surface portion 26 of the concave portion 24 of the lower die 20, and at the same time, the lower corner portion 44 is abutted by the slope portion 28 of the lower die 20. At the same time, the lower surface portion 42 of the yoke core 4 is formed flat by the bottom surface portion 26 of the lower mold 20, while the upper surface portion 40 of the yoke core 4 is pressed by the upper mold 22 and flattened by the lower surface portion 30. Molded.
[0021]
At this time, as shown in FIG. 4, it is possible to adopt a form in which a vertical side surface portion 29 is formed from the outer end portion of the concave portion 24 of the lower mold 20. Then, the yoke core 4 is fitted in a close contact state between the side surface portions 29 of the lower mold 20. In this case, the yoke core 4 is fixed by the side surface portion 29 of the lower mold 20 as shown in FIG. 9A, and in this state, the yoke core 4 is pressed by the upper mold 22 as shown in FIG.
[0022]
According to the lower mold 20 in this form, the fixing of the yoke core 4 is stabilized by holding the side surface portions 29. Further, by setting the interval between the side surface portions 29 to be substantially the same as the width interval of the yoke core 4, the yoke core 4 is prevented from being crushed in the left-right direction when the yoke core 4 is pressed. The left and right wall surfaces of the core 4 are uniformly formed.
[0023]
By this pressing, the yoke core 4 is formed with the upper surface portion 40 and the lower surface portion 42 flat as shown in FIG. 2 ((2), (3)). Further, the lower corner portion 44 of the yoke core 4 is faced, and the upper corner portion 46 of the yoke core 4 has a shape in which the roundness formed at the time of the punching is left. The imposition of the yoke core by the press working can be performed more quickly than the imposition by the polishing process, and an accurate cross-sectional shape can be obtained by molding each surface of the yoke core.
[0024]
When the pressing process is completed, the yoke core is subjected to a surface treatment such as galvanization by a plating process. Thereafter, the yoke core is inspected, and the appearance of the plating and the finished accuracy of the yoke core are inspected. The yoke core that has passed the inspection is transferred to the next insertion press-fitting process.
[0025]
In this insertion press-fitting step, the yoke core 4 is press-fitted into the short ring 6. The short ring 6 is made of a rectangular copper tube having a rectangular cross section, and the length in the longitudinal direction is shorter than that of the yoke core 4. The short ring 6 is manufactured by pulling out a copper round pipe. At this time, first, both the upper and lower sides of the round pipe are compressed by a rotating roller supported by a horizontal shaft to form flat upper and lower surfaces, and then the left and right side surfaces of the pipe are rotated by a vertical shaft. To form a flat side surface to obtain a rectangular square pipe. Regarding the dimensions of the short ring 6 and the yoke core 4, when the yoke core 4 is press-fitted into the short ring 6, the upper, lower, left and right surfaces of the yoke core are in close contact with the corresponding surfaces of the short ring 6. Determine the size of each.
[0026]
As shown in FIG. 5, the insertion press-fitting step is a step of inserting and attaching a part of the short ring 6 to the yoke core 4 (FIG. 5A), and the short ring 6 with the yoke core 4 is inserted into the press-fitting jig 50. And the step of press-fitting the yoke core 4 into the short ring 6 by the pressing machine 52 (FIG. 5C).
[0027]
As shown in FIG. 5B, the press-fitting jig 50 has a first jig 54 provided with a through-hole 53 having a rectangular cross section and a rear part of the first jig 54 and has a rectangular cross section. It consists of a second jig 56 provided with a hole 55. The through hole 53 is formed so that the four surfaces of the short ring 6 can be closely inserted, and the hole 55 is in contact with the surface portion 58 of the hole 55 so that only the yoke core 4 is It is formed in a size that can be inserted into the hole 55.
[0028]
Further, the yoke core 4 protrudes from both ends of the short ring 6 by a predetermined length, and when it is assembled as a VCM yoke, it is necessary to use it as a joint with other members. For this reason, the depth of the hole 55 coincides with the length of the yoke core 4 protruding from the short ring 6. The press-fitting jig 50 includes a first jig 54 and a second jig 56. These jigs 54 and 56 are integrally formed, and the surface portion 58 is a stepped portion. Tools can also be used.
[0029]
In the step of inserting the yoke core 4, the yoke core 4 is partially inserted into the short ring 6 and temporarily fixed. At this time, the lower corners of the yoke core 4 are faced and the upper corners are rounded, so that the yoke core 4 can be easily inserted and inserted. Here, a part of the yoke core 4 is inserted into the short ring 6.
[0030]
Next, in the insertion process of the yoke core 4, the short ring 6 into which the yoke core 4 is partially inserted is inserted into the first jig 54. In this insertion, the short ring 6 is inserted up to the rear end portion of the first jig 54, and the short ring 6 comes into contact with the surface portion 58 of the second jig 56 at this position, and stops at this position.
[0031]
In the next press-fitting process, the yoke core 4 is press-fitted into the short ring 6 by using the pressing machine 52. The pressing machine 52 is composed of an air cylinder using air pressure, and press-fits by applying a pressing force of 98 N (10 Kgf). During the press-fitting, it is conceivable that a force that deforms (shears) the short ring 6 due to a frictional force with the yoke core 4 acts, but the short ring is caused by the through hole 53 of the first jig 54 for this. The outside of 6 is restrained and the deformation of the short ring 6 is prevented.
[0032]
In the finish in this press-fitting process, the finish accuracy of the yoke core 4 made of a material harder than the short ring 6 has a great influence, but the upper surface portion 40 and the lower surface portion 42 of the yoke core 4 are particularly flat and highly accurate due to the above pressing. Therefore, the yoke core 4 is finished in such a state that the upper, lower, left and right surfaces can be in close contact with each other on the inner wall surface of the short ring 6. Further, since the four corners of the yoke core 4 are not angular, this portion does not generate excessive frictional resistance during press-fitting and cause the short ring 6 to be sheared. Therefore, press-fitting can be performed well in this respect.
[0033]
Further, after the yoke core 4 has penetrated the short ring 6 due to the press-fitting, the yoke core 4 is directly inserted into the hole 55 of the second jig 56 and further inserted until the yoke core 4 contacts the bottom surface of the hole 55. Stop at this position. Thereby, the yoke core 4 can be protruded from the both ends of the short ring 6 by a desired length.
[0034]
Therefore, according to the above-described embodiment, the press-fitting of the yoke core into the short ring can be performed well and accurately, and a strong holding force is obtained by the four-surface press-fitting of the yoke core, and the finishing accuracy of the VCM yoke is good. Moreover, it can be manufactured easily and is economical.
[0035]
FIG. 6 shows another form of the insertion press-fitting process. In this step, a part of the short ring 6 is inserted into the yoke core 4 and attached, and the end of the yoke core 4 of the short ring 6 with the yoke core 4 is inserted into the hole 61 of the fixing jig 60 and fixed. The process includes a step (FIG. 6A) and a step (FIG. 6B) in which the yoke core 4 is press-fitted into the short ring 6 by the pressing machine 62.
[0036]
In the press-fitting, as shown in FIG. 6A, a fixing jig 60 provided with a hole 61 having a rectangular cross section and a pressing machine 62 for press-fitting the short ring 6 into the yoke core 4 are used. The depth of the hole 61 of the fixing jig 60 is made to coincide with the length that the yoke core 4 protrudes from the short ring 6 after the press-fitting is completed.
[0037]
The pressing machine 62 includes a base 65 pressed by an air cylinder, a hole 63 having a rectangular cross section provided in the axial direction of the base 65, and the inside of the hole 63 and the inside of the short ring 6. A guide body 64 that guides the yoke core 4 that slides and is inserted into the short ring 6, and a coil spring 66 are provided. The hole 63 is formed in such a size that the end of the short ring 6 is in contact with the surface and only the yoke core 4 can enter. As shown in FIG. 6A, the guide body 64 is held by a coil spring 66 so that one half of the guide body 64 protrudes from the hole 63 of the pressing machine 62 when no load is applied.
[0038]
In the step of inserting the yoke core 4, a part of the yoke core 4 is inserted into the short ring 6 and temporarily fixed. In the step of fixing the yoke core 4, as shown in FIG. 6 (a), the tip of the yoke core 4 to which the short ring 6 is temporarily fixed is inserted into the hole 61 of the fixing jig 60 and fixed. A guide body 64 protruding from the base portion 65 of the pressing machine 62 is inserted into the end portion of the short ring 6.
[0039]
In the next press-fitting step, the yoke core 4 is press-fitted into the short ring 6 using a pressing machine 62 as shown in FIG. At the time of press-fitting, the short ring 6 that contacts the end of the base portion 65 of the pressing machine 62 is pressed, and the entire short ring 6 is press-fitted into the yoke core 4, and then the yoke core 4 is guided by the guide body 64. Into the hole 63 of the base 65. Further, the press-fitting is finished in a state where the press-fitting is performed and the end portion of the short ring 6 is in contact with the surface portion of the fixing jig 60. By this press-fitting, the yoke core 4 can be protruded from the both ends of the short ring 6 by a required length.
[0040]
【The invention's effect】
As described above, according to the method for manufacturing a yoke for VCM according to the present invention, the step of obtaining a yoke core by punching, the step of imposing the yoke core, and the press-fitting into a state where the tip of the yoke core protrudes from the pipe Therefore, the manufacturing process can be easily performed, and the insertion and press-fitting of the yoke core into the pipe can be performed smoothly and smoothly.
[0041]
According to the method for manufacturing a yoke for a VCM according to the present invention, in the insertion press-fitting step, the step of inserting a part of the yoke core into the pipe, the pipe on the jig having a step portion where the tip of the pipe abuts and the yoke core passes through Since there is a step of inserting the yoke core and a press-fitting step of press-fitting the yoke core, there is an effect that the yoke for the VCM can be smoothly and stably inserted into the pipe and the yoke can be accurately obtained. .
[0042]
According to the method for manufacturing a yoke for VCM according to the present invention, in the imposition step, a lower die having a flat bottom surface portion and a concave portion is used, and the yoke core is disposed in the middle of the inclined surface portion. Since the upper die is pressed from above to perform imposition, the corners of the yoke core can be easily and quickly impositioned, and the upper and lower surface portions of the yoke core are formed flat and with high accuracy. There is an effect that a yoke core is obtained.
[0043]
According to the method for manufacturing a yoke for a VCM according to the present invention, the upper, lower, left, and right surfaces of the yoke core are sized so as to be in contact with each surface of the corresponding pipe evenly. There is an effect that a good holding characteristic is obtained.
[Brief description of the drawings]
1A and 1B are views showing a VCM yoke according to an embodiment of the present invention, in which FIG. 1A is a front view, FIG. 1B is a plan view, and FIG. 1C is an AA enlarged sectional view;
FIG. 2 is a view showing a cross section of a yoke core according to the embodiment.
FIG. 3 is an explanatory diagram of a process for imposing a yoke core according to the embodiment, (a) is a diagram showing a pressed state, and (b) is a partial view.
4A and 4B are diagrams showing a lower mold and a yoke core according to the embodiment, in which FIG. 4A shows a state before pressing, and FIG. 4B shows a state after pressing.
FIGS. 5A and 5B are diagrams showing a press-fitting process according to the embodiment, in which FIG. 5A shows a process of attaching a yoke core to a short ring, and FIG. 5B shows a process of inserting the short ring into a press-fitting jig; ) Shows a step of press-fitting the yoke core into the short ring.
6A and 6B are diagrams showing another embodiment of a press-fitting process, in which FIG. 6A shows a step of fixing a yoke core on which a short ring is mounted, and FIG. 6B shows a step of press-fitting the short ring into the yoke core by a pressing machine.
FIG. 7 is a diagram showing a part of a VCM (voice coil motor).
[Explanation of symbols]
4 Yoke core 6 Pipe (short ring) 20 Lower mold 22 Upper mold 24 Recess 26 Bottom face 28 Slope 29 Side face 44 Lower corner 54 First jig 56 Second jig

Claims (4)

A step of obtaining a yoke core made of a long steel magnetic material by stamping;
The yoke core obtained by punching is used as a lower mold having a flat bottom surface portion and concave portions formed with slope portions on both sides of the bottom surface portion, and the yoke core is placed on the long side in the middle of the slope portion. place in a state where the lower corner hits respectively, by pressing the upper die bottom surface is flat over the yoke core, have rows imposition on both lower corners of the long side of the yoke core, at the same time Forming a lower surface portion and an upper surface portion of the yoke core flatly ;
Inserting a part of the yoke core into a copper pipe having a rectangular cross section ;
The pipe with the yoke core into which the yoke core is inserted is put into a jig having a hole portion into which the pipe can be inserted, a step portion with which the tip of the pipe abuts, and a hole portion into which only the yoke core can be inserted. The step of inserting the tip of the step to the step,
A method of manufacturing a yoke for a VCM, comprising: a press-fitting step in which the yoke core is inserted into the pipe by press-fitting the yoke core, and a tip portion of the yoke core passes through the pipe and enters the hole . The jig is
A first jig having a through hole into which the pipe with the yoke core can be inserted;
And a second jig having a hole with a predetermined depth in which a cross section is smaller than the through hole, the pipe is in contact with a surface portion, and only the yoke core can be inserted. 2. A method for manufacturing a yoke for VCM as described in 1 . A side surface part into which the yoke core can be fitted is provided on both sides of the recess of the lower mold, and the upper mold is pressed by holding the yoke core between the side surfaces. A method for manufacturing a yoke for a VCM according to claim 1 or 2 . The size of each member is determined such that when the yoke core is press-fitted into the pipe, the upper, lower, left and right four surfaces of the yoke core are evenly in contact with the corresponding surfaces of the pipe. The manufacturing method of the yoke for VCM in any one of Claim 3 .

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