JPH09308153A - Method of manufacturing rotor frame for spindle motor - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] A spindle motor turntable component and a rotor magnet frame component for rotationally driving a recording member such as an optical disc or a magnetic disc are provided with high precision and high rigidity.
Also, a manufacturing method by co-processing from a single plate member is provided for high efficiency production. SOLUTION: In the step of forming a single plate member into a hollow cylindrical body, after forming an annular projecting shape on the end wall side of the joining portion of the end wall section and the cylindrical section, the annular projecting shape is formed in the outer circumferential direction. A manufacturing method mainly composed of press processing in which a turntable part having a diameter larger than that of a cylindrical part is formed by performing a drawing process to form a turntable part and a rotor magnet frame part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor for rotatably driving a recording member such as an optical disk and a magnetic disk, and in particular, by combining a turntable and a rotor magnet frame into one component, it is possible to achieve high accuracy. The present invention relates to a manufacturing method that can be provided at low cost.

[0002]

2. Description of the Related Art Spindle motors generally used for rotating a recording member include, for example, one shown in FIG. 9, in which a turntable and a rotor magnet frame are processed by different members. It is based on the structure that it is mounted on the same rotary shaft.

The turntable is generally formed by a method such as turning with a cutting tool, die casting, or forging, and the turntable alone is attached and fixed to a rotary shaft.

On the other hand, the rotor magnet frame is generally formed in the shape of a hollow cylinder having a frame portion formed by subjecting a plate member to drawing and ironing and a shaft fixing portion formed by burring. ,
The rotor magnet frame alone is attached to the rotating shaft. As a means for mounting the rotary shaft, for example, a method such as press fitting, adhesion, or screwing is used.

As a method of restricting the position of the magnet mounted on the inner surface of the rotor frame, a method of forming cut-and-raised portions or projections at a plurality of positions on the inner surface of the frame cylindrical portion is generally used.

[0006]

In the conventional method of processing a turntable, it is desired to press a plate member which is excellent in productivity and cost, and from the viewpoint of strength and cost, a rotor magnet frame is desired. However, there is no method for integral processing, and there is a problem in strength and accuracy in press processing using only a turntable, and cutting and die casting and Methods such as forging have been implemented.

[0007] Further, since the integration is desired but there is no realization method, the turntable and the rotor magnet frame are formed as separate parts by different processing means and are attached to the same rotary shaft. Was required for each of them, which had an effect on the rotation accuracy, and at the same time prevented miniaturization and cost reduction of the spindle motor.

[0008]

A hollow cylindrical body having an end wall portion and a cylindrical portion, which is of a rotationally symmetrical center axis and is formed by drawing and ironing a plate material by a general press, comprises:
The end wall portion and the cylindrical portion have a complementary relationship in strength and accuracy, and the shape accuracy to be formed depends on the mold structure and the processing accuracy, the clearance accuracy between the molds, and the like. After forming an annular projecting shape on the end wall side of the joint between the end wall portion and the cylindrical portion in the step of forming the single plate member into the hollow cylindrical body, the annular projecting shape is drawn so as to fall in the outer peripheral direction. By forming a turntable part with a diameter larger than the cylindrical part on the end wall and integrating it with the rotor magnet frame part of the cylindrical part, integrated parts with excellent precision and strength can be pressed with high productivity. It is a method of manufacturing by the method.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1, 2 and 3
1 is an embodiment according to the present invention, FIG. 1 is a perspective view,
2 is a sectional view and FIG. 3 is a plan view.

FIG. 4 is a schematic view of a spindle motor in which a rotor frame according to an embodiment of the present invention is incorporated, in which a burring portion formed in a central portion is provided with a bracket 1.
8, the bearing 16 fixed to the rotary shaft 8 and the rotary shaft 15 inserted in a freely rotating state are press-fitted and fixed, the rotor magnet 17 is mounted on the inner surface of the frame portion, and the media adjustment is performed from the square hole formed in the media guide portion. The outline of the rotor frame in a state where a part of the core ring 19 is projected is shown.

FIGS. 5 (a) to 5 (j) are schematic views of a working process showing one embodiment of the present invention, and FIG. 6 is an intermediate body formed by the working process of the present invention-an embodiment. FIG. 5A to 5J and FIG. 6 will be described.

The first step shown in FIG. 5A is a blank removing step. Circular through hole 22 of blank removal lower mold 21
And the blank punching section 24 of the blank punching upper die 23.
The outer diameter of is compatible. After the plate member 25 is positioned on the lower mold 21, the upper mold 23 is moved up and down in the direction of the arrow, and the plate member 25 is punched by the action to form a circular blank 25 (a). As the plate member 25, for example, a plate-like member formed of iron such as copper or copper alloy, aluminum or aluminum alloy, or cold rolled steel plate is used, and its thickness is preferably 1 mm or less.

The second step shown in FIG. 5B is a square hole removing step. Six square punches 28 arranged at equal angles from the center of the square hole die 27 are fixed to the square hole die 27. The lower rectangular die 26 has a through-angled hole 29, and the through-angled hole 2
9 and the shape and position of the rectangular punch 28 correspond to each other. Further, the lower die 26 is provided with a guide portion 30 for positioning the blank material 25 (a). After the blank material 25 (a) is positioned on the lower die 26 according to the guide portion 30, the upper die 27 is moved up and down in the unmarked direction to form a blank material 25 (b) in which the square holes are punched out. To be done.

The order of the first step and the second step has been described as a specific example of this embodiment, but is not limited thereto.
However, it is desirable to carry out in the subsequent steps from the third step to the tenth step. The reason for this is that the punching after forming the shape such as drawing and ironing from the third step complicates the mold structure and deteriorates the productivity.

The third step shown in FIG. 5C, the fourth step shown in FIG. 5D, and the fifth step shown in FIG.
(E) and a process from drawing to ironing until the intermediate body 50 shown in FIG. 6 is formed.

The third step shown in FIG. 5C is the intermediate 50.
Is a step of forming a part of the media guide portion and the annular protruding portion formed on the end wall portion of. The end wall forming lower die 31 has shapes 32 and 3 corresponding to the shape of the media guide portion and the annular protruding portion.
5 has an annular groove, and the end wall forming upper die 34 has an annular projection shape 3 corresponding to the annular groove shapes 32 and 35 of the lower die 31.
3 and 36 are formed.

The blank material 25 (b) is positioned on the lower die 31, and the upper die 34 is moved up and down in the direction of the arrow to perform drawing work.
(C) is formed. In addition, the annular protrusion shape 3 of the upper mold 34
If the tip corner portion of 6 and the inlet portion and the bottom portion of the annular groove shape 35 of the lower die 31 are rounded with a radius of half or more of the plate thickness of the plate member 25, it is possible to prevent breakage of the blank material. confirmed.

The fourth step shown in FIG. 5D is the intermediate 50.
It is a first drawing step before forming the.

The first lower drawing die 41 is the lower drawing 3 of FIG.
1 and the same shape (32 and 35) annular groove and the central axis angle is 45
An angled surface 42 is formed. The first diaphragm upper mold 45 is
An annular protrusion having the same shape (33 and 36) as that of the upper mold 34 in FIG. 5C is formed, and the position restricting portion 43 and the pressing compression spring 48 are located on the upper surface and the inner peripheral surface of the fixed upper mold 47. It is configured to slide. The fixed upper die 47 is the lower die 45 of the lower die 41.
It has a drawing die surface 46 having a shape corresponding to the angled surface 42, an inner peripheral surface that guides the outer peripheral surface of the upper die 45, and a compression spring 48.
It is formed in a built-in cylindrical shape and is fixed by a fixing portion 49.

The blank 25 (c) formed in the step of FIG. 5 (c) is positioned along with the shape of the lower die 41, and the fixed upper die 47 is moved up and down in the direction of the arrow so that the upper die 45 is simultaneously moved. The blank material 25 (c) is pressed by the lower die 41 with a compression spring force by moving up and down. Further, by moving the fixed upper die 47 up and down, the blank material 25 (c) is drawn by the die surface 42 of the lower die 41 and the die surface 46 of the upper die 45 to form the blank material 25 (d). It Although the central axis angle 45 angle shape (42 and 46) has been described as a specific example of the present embodiment, the angle is in the range of 30 to 60 angles and a radius of several times the plate thickness of the play member 25 or more. It has been confirmed that the rounded shape of is a possible range for forming an intermediate without breaking.

The fifth step shown in FIG. 5 (e) is a step of forming a cylindrical body (intermediate body 50) by ironing. The ironing lower die 51 is formed with an annular groove having the same shape (32 and 35) as the lower die surface in the steps of FIGS. 5C and 5D.
The outer circumference has a dimension and shape corresponding to the rotor magnet mounting surface 11. The configuration of the ironing upper die 52, the fixed upper die 54, the pressing compression spring 55, and the fixing portion 56 is shown in FIG.
The fourth step is similar to the die structure, but there is a difference in the shape of the squeezing surface 53 of the fixed upper die and the compression spring force.

Blank 25 formed in the fifth step
(D) is located on the lower mold 51, and the fixed upper mold and the upper mold are moved up and down in the direction of the arrow, thereby lowering the lower mold 51 and the upper mold 52.
While holding the blank material 25 (d) between them and holding it by the action of the force of the compression spring 55, the fixed upper die is further moved up and down, and the blank member is ironed by the ironing die portion 53 of the fixed upper die 54. A cylindrical body 50 is formed.

Although the plate thickness of the plate member 25 is defined by JIS standard, the length of the cylindrical body formed by the ironing process varies due to the tolerance variation and the like. It is common to cut it off.

FIG. 6 is a schematic sectional view showing the shape of the intermediate body formed by the above process. The rounded shape of the tip of the annular protruding portion b formed between the cylindrical outer peripheral surface c and the end wall side a and the roundness at which the end wall reference surface 8 and the annular protruding surface a contact each other are equal to the plate member 25 plate thickness or It is formed with a radius of equal or greater radius. The protrusion height y from the end wall reference surface 8 is proportional to the protrusion length z of the turntable portion 1. The inner peripheral surface of the cylinder is formed with the required accuracy as the rotor magnet mounting surface 11, and the top surface 6 of the end wall, the media alignment guide surface 5 and the square hole 12 are provided with the required shape and accuracy as the media guide portion 2. ing. Although the thickness of the intermediate body varies depending on the location, it is formed to be equal to or less than the plate thickness of the plate member.

The sixth step shown in FIG. 5 (f) and the seventh step shown in FIG. 5 (g) are drawing steps for forming the turntable portion.

The sixth step in FIG. 5 (f) is the first drawing step for forming the turntable portion. A diaphragm lower die 60 having a shape corresponding to the inner peripheral surface of the intermediate body 50 excluding the annular protruding portion, and a diaphragm side die 61 (a) for holding the intermediate body 50 located on both left and right sides of the lower die 60. (B) and lower mold 60
Of the upper surface of the lower die 60 and the side surface of the lower die 60 in the height positional relationship between the reference surface of the lower die 60 and the side die. A step (x) having the same size as that of is provided.

After placing the intermediate body 50 on the lower die 60 and holding the intermediate body 50 by the side dies 61 (a) and (b), the upper die 62 is formed.
Move up and down in the direction of the arrow. As the upper die 62 moves up and down, the diaphragm die surface at a specific angle moves up and down to draw and bend the annular protrusion of the intermediate body 50 from the inner peripheral side to the outer peripheral side. Due to this specific angle of the drawing die and its action, the intermediate thickness of each of the annular protrusions falls by a predetermined amount in the outer peripheral direction while maintaining the initial thickness substantially, and the intermediate body having a stable turntable primary shape without material breakage. 5
0 (a) is formed.

The seventh step of FIG. 5 (g) is a drawing step for forming the turntable portion. The basic configuration is the same as in the sixth step, except that the drawing die of the shape forming upper die 65 is a flat drawing die that is different from the specific angle drawing die of the previous sixth step, and the shape forming lower die 63 and the shape forming are performed. The side mold 64 (a) (b) and the upper mold 65 are constituted, and the lower mold 63 and the side mold 64 (a) are formed.
In the height relationship of (b), a step (x) is provided.

The intermediate body 50 (a) having the first throttle of the turntable is positioned on the lower mold 63 and held by the side molds 64 (a) (b) in the same manner as the above process, and the upper mold 65 is moved in the direction of the arrow. An intermediate body having an annular flat turntable portion perpendicular to the center is formed by upwardly and downwardly downwardly bending an annular protrusion formed at a specific angle from the upper side to a lower side by a die portion of the upper die 65. (B) is formed.

The eighth step shown in FIG. 5 (h) is a drawing step in which the position-controlling annular projection of the rotor magnet is formed inside the intermediate body. Although the basic configuration is the same as the previous seventh step in the configuration of the position regulation lower mold 66, the position regulation side molds 67 (a) and (b), and the position regulation upper mold 68, in order to form the annular magnet stop surface 10. The annular convex portion 69 of the upper mold 68
And a shape corresponding to the shape is formed on the lower mold 66.

Intermediate 50 having a turntable portion formed
(B) is positioned on the lower mold 66 and held by the side molds 67 (a) and (b) in the same manner as in the above step, and the upper mold 68 is moved up and down in the direction of the arrow, so that a V-shaped cross section is formed inside the cylinder. An intermediate body 50 (C) having a mold-shaped annular protrusion is formed.
In this process, breakage is likely to occur, but it is important that the shapes of the lower mold 66 and the upper mold 68 corresponding to the V-shaped tip and the root have appropriate roundness.

The ninth step shown in FIG. 5 (i) is a burring pilot hole punching step. The lower hole lower mold 70 has a shape corresponding to the inner peripheral surface of the intermediate body 50 (c) formed in the previous eighth step, and has a penetrating round hole 74 adapted to the lower hole for burring on the center line. There is. The lower hole upper die 72 is formed with a lower hole punch portion 73 having a diameter corresponding to the through round hole 74 of the lower die 70. Position the intermediate body 50 (c) on the lower mold 70,
When the upper die 72 is moved up and down in the direction of the arrow, a lower hole having a positional relationship concentric with the inner peripheral surface 11 of the intermediate body 50 (c) is punched out, and the intermediate body 50 (d) is formed.

The tenth step shown in FIG. 5 (j) is a burring step. Burring lower mold 75 and burring upper mold 7
6, the lower mold 75 has a hole having a diameter corresponding to the outer diameter of the burring protrusion, and the upper mold 76 has a cylindrical protrusion 77 having a diameter corresponding to the inner diameter of the burring and a conical tip. There is. The burring amount is the clearance generated when the hole of the lower mold 75 and the cylindrical protrusion of the upper mold 76 correspond to each other.

The intermediate body 50 (d) is located on the lower die 75, and the upper die 76 is moved up and down in the direction of the arrow to perform burring, which has the shape, precision and rigidity necessary for fixing the rotary shaft. The cylindrical portion is formed inside, and the integrated rotor frame is completed.

(Embodiment 2) FIGS. 7A to 7
FIG. 3E is a schematic view of a mold structure showing the embodiment of the present invention and a forming process situation by the mold.

FIG. 7 (a) is a schematic view of the mold structure and the plate material (a) positioned on the mold. A die having corresponding die surfaces is formed vertically to form the end wall portion, the lower die 80 having a structure of sliding on the outer peripheral surface and the fixed upper die 83 are made to correspond at the center, and the slide lower die 80 slides. Fixed lower die 81 having an inner surface and an ironing die surface as a diaphragm
And a compression spring 82 for supporting the lower slide mold 80 from below.
And a lower mold part, and a stripper 84 and a compression spring 86 for the stripper 84 on the outer peripheral part of the fixed upper mold 83.
And a holder 85 that supports the stripper.

FIG. 7B shows a state in which the lower die 83 is in the first stage of descending and the media guide portion is formed.

FIG. 7 (c) shows a state in which the lower die 83 is descending in the second stage, and a situation in which the diaphragm and the ironing are simultaneously progressing between the die surface of the fixed lower die 81 and the upper die 83. .

FIG. 7 (d) shows that the stepped portion formed on the outer peripheral surface of the upper die 83 and the fixed lower die 81 collide with each other when the lowering of the upper die 83 approaches the lowest point. Show. At this point, the stripper 84 is exerting a force through the blank material and a gap is formed between the stripper 84 and the holder 85.

FIG. 7E shows the upper mold 8 after the forming operation is completed.
3 shows a state of rising. The lower die 80 returns to the original state, and the stripper 84 of the upper die 83 functions by the action of the compression spring 86 to remove the chips 87, and the intermediate body 50 is taken out.

(Third Embodiment) FIGS. 8A and 8B.
FIG. 3 is a process outline view showing an embodiment of the present invention.

FIG. 8A shows a hollow cylindrical body 90 formed by general drawing and ironing.

FIG. 8 (b) shows a hollow cylindrical body 90 with a rotary die 9
1 and a holder 92 to rotate the end wall portion of the hollow cylindrical body with a roller 93 supported by a holder 94 by a shaft 95 and having a rounded tip. The meat is gradually moved to form protrusions and form a blank 96.

The blank 96 is punched with square holes, media guides are formed, magnets are formed and burring is performed to complete an integral rotor frame.

[0046]

According to the integrated manufacturing technique of the plate member of the present invention, a highly accurate and highly rigid evening table and a rotor magnet frame can be integrally realized at low cost, and a spindle motor can be made thin. Also improved high-speed rotation performance.

The present invention is to reduce the number of parts and the number of assembling by making the assembled structure of multi-parts into a single part, and it has an effect that it can be applied to mechanical parts in various fields.

[Brief description of drawings]

FIG. 1 is a conceptual perspective view of a rotor frame integrally formed.

FIG. 2 is a conceptual sectional view of a rotor frame formed integrally.

FIG. 3 is a conceptual plan view of a rotor frame formed integrally.

FIG. 4 is a conceptual cross-sectional view of a spindle motor that incorporates a rotor frame that is integrally formed.

FIG. 5 is a conceptual cross-sectional view of steps showing a method for manufacturing an integrated rotor frame.

FIG. 6 is a conceptual cross-sectional view of an intermediate body formed in the manufacturing process of the integrated rotor frame.

FIG. 7 is a conceptual cross-sectional view of a pair of mold structures in the manufacturing process of the integrated rotor frame and the progress of the shape forming process by the molds.

FIG. 8 is a conceptual sectional view of a manufacturing process of an integrated rotor frame by a roller ironing method.

FIG. 9 is a conceptual sectional view of a general spindle motor.

[Explanation of symbols]

 1 turntable part 2 media guide part 3 rotor magnet frame part 4 turntable surface 5 media alignment guide surface 6 top surface 7 shaft fixing surface 8 end wall reference surface 9 turntable back surface 10 magnet stop surface 11 rotor magnet mounting surface 12 square Hole 13 Burring part 14 Magnet position restriction part 15 Rotating shaft 16 Bearing 17 Rotor magnet 18 Bracket 19 Media centering ring 21 Blank blank lower mold 22 Circular through hole 23 Blank blank upper mold 24 Blank blank punch 25 Plate member (blank material) 26 Square hole lower die 27 Square hole upper die 28 Square punch 29 Through square hole 30 Blank guide portion 31 End wall forming lower die 34 End wall forming upper die 35 Annular protrusion (lower) 36 Annular protrusion (upper) 41 First drawing lower Mold 42 Angled surface 43 Position restriction part 4 First drawing upper mold 46 Drawing mold surface 47 Fixed upper mold 48 Pressing compression spring 49 Fixed part 50 Intermediate 51 Ironing lower mold 52 Ironing upper mold 53 Ironing surface part 54 Fixed upper mold 55 Compression spring 56 Fixed part 60 Throttling lower mold 61 Aperture side mold 62 Aperture upper mold 63 Forming lower mold 64 Forming side mold 65 Forming upper mold 66 Position regulation lower mold 67 Position regulation side mold 68 Position regulation upper mold 69 Annular convex portion 70 Lower hole Lower mold 72 Lower hole Upper Mold 73 Lower hole punch 74 Through round hole 75 Burring lower mold 76 Burring upper mold 77 Cylindrical protrusion 80 Slide lower mold 81 Fixed lower mold 82 Drawing compression spring 83 Fixed upper mold 84 Stripper 85 Stripper retainer 86 Stripper spring 87 Cutting waste 90 Hollow cylinder 91 Rotating type 92 Rotating holder 93 Ironing roller 94 Roller holder 95 Over La shaft 96 ironing formation GOODS

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaichiro Tachikawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. An end wall part formed of a single plate member and having a media guide part for aligning and guiding a media center hole of an optical disk or a magnetic disk (media), and a turn for receiving and rotating a side surface of the media. A hollow cylindrical body having an annular projecting portion in which a table portion is formed and in contact with an end wall portion and a cylindrical portion, and a cylindrical portion having an inner peripheral surface for mounting a rotor magnet, wherein the end wall portion includes: A media guide part formed to project toward the outside of the hollow cylindrical body having a top surface part having a hole for fixing the rotary shaft in the center part and a media centering guide surface in contact with the top surface part at a specific angle gradient And the media centering guide surface contact with the end wall reference surface that is in contact with a rounded radius less than the plate member plate thickness and spreads in the outer peripheral direction, and is in contact with the end wall reference surface with the same or a step, and the outer periphery is perpendicular to the central axis. An annular protrusion having a turntable surface that spreads in the direction is formed.The annular protrusion has a turntable surface and an end portion of the turntable that has a radius equal to or less than the plate member plate thickness. It is folded back in the direction to form the back surface of the turntable and is in contact with the cylindrical part. A method of manufacturing a rotor frame for a spindle motor, which is formed in a cylindrical shape for mounting a rotor magnet on the inner peripheral surface of the plate, and which includes performing punching, drawing, and ironing on one plate member. In the process of forming a hollow cylindrical body having a media centering guide portion of the end wall portion and a cylindrical portion for mounting the rotor magnet. In addition, the shape of the corner portion where the end wall portion and the cylindrical portion are in contact with each other is turned inward at an angle of 180 degrees with a roundness of the center radius equal to or more than the outer peripheral portion of the cylindrical portion and the plate member plate thickness. An intermediate body with an annular protrusion shape that is in contact with the cylinder at a right angle is formed, and the annular protrusion of the intermediate body is subjected to a drawing process in the outer peripheral direction in a subsequent process to form a plane perpendicular to the central axis. A spindle motor characterized by integrally forming a media guide part, a turntable part, and a rotor magnet frame part by forming a turntable part having a larger diameter than the diameter and having an annular flat surface for receiving a medium. Rotor frame manufacturing method. 2. The method for forming a hollow cylindrical body according to claim 1, wherein the end wall portion has a hole for fixing the rotary shaft at the center portion or a cylindrical protrusion formed to protrude toward the inside of the hollow cylindrical body. A media guide formed by projecting toward the outside of a hollow cylindrical body having a top surface portion having a portion and a top surface portion contacting at a specific angle gradient and having a media alignment guide surface in which several square holes are formed in the periphery. Part, the media centering guide surface, and the end wall reference surface that is in contact with the plate member plate thickness with a radius less than or equal to the radius and spreads in the outer circumferential direction, and the end wall reference surface that contacts the end wall reference surface at a specific angle gradient A magnet position regulation part is formed that has a V-shaped cross section and has a V-shaped cross section that is folded back by a radius and is in contact with the turntable surface. The magnet protrusion part side surface is formed on the annular protrusion that is in contact with the end wall. Play with A turntable part is formed that has a turntable surface that is in contact with a roundness with a center radius greater than the thickness of the plate member and that extends in the outer peripheral direction perpendicular to the center axis, and the end of the turntable surface is equal to the plate member plate thickness or It is folded back in the axial direction with a radius of less than that to form the back surface of the turntable and is in contact with the cylindrical part. The cylindrical part has a radius at the center radius equal to or less than the plate member plate thickness and the back surface of the turntable. The rotor for a spindle motor according to claim 1, wherein the rotor is for a spindle motor and is formed in a hollow cylindrical body which is in contact with the turntable and is positioned at a right angle to the back surface of the turntable and has a rotor magnet mounted on the inner peripheral surface thereof. Frame manufacturing method. 3. A method for forming a square hole formed on a side surface of a media guide portion of an end wall portion according to claim 1, wherein punches are formed at several positions equidistant from the center of the plate member. The shape of the square hole punched with a die
The trapezoid has a wide center side and a narrow outer side, and the side of the trapezoid is narrow inward, and each corner of the trapezoidal hole has a radius equal to or greater than the slope thickness of the plate member. By rounding the dimensions, the plate member is subjected to drawing and ironing, etc. to form a part of the end wall reference surface from the top surface of the media guide section of the end wall section through the media alignment guide surface. The shape of the square hole
The method of manufacturing a rotor frame for a spindle motor according to claim 1, wherein each of the corners has a rectangular shape with a rounded shape when viewed from a plane (top surface side) direction. 4. A method for forming an intermediate body in which an annular protrusion is formed on an end wall portion according to claim 1 or 2, wherein a square hole is punched out at several positions. In the process in which the media guide part and a part of the annular protrusion of the intermediate body are formed by drawing, the mold structure is lowered in the process of drawing and ironing to form the cylindrical part A mold and an upper mold having a shape corresponding to the lower mold,
It has a cylindrical shape with a compression spring that pushes down the upper mold, a space that houses the compression spring that guides the outer peripheral surface of the upper mold, a squeeze in the lower part, and an ironing mold surface and a fixing part to the press in the upper part. Using a mold that is basically composed of a fixed mold part, a process product is sandwiched between a lower mold and an upper mold, and a diaphragm located on the outer periphery of the upper mold while being pressed by the force of a compression spring. 2. The ironing upper die is lowered to perform drawing and ironing, thereby forming an intermediate body which is free from changes in shape and breakage of the formed square holes and media guide portions. Manufacturing method of rotor frame for spindle motor. 5. A method for forming an intermediate body having an annular projection formed on an end wall portion according to claim 1 or 2, wherein the mold structure has a compression spring located below the intermediate structure. Corresponding to the slide lower mold, the slide lower mold that moves up and down by the action of the spring, the fixed lower mold that has the inner peripheral surface that slides and guides the lower mold, the slide stopper of the lower mold, and the mold surface that works by squeezing from the diaphragm Fixed upper die having a shaped die surface and a stepped outer peripheral surface, a stripper located on the outer periphery of the fixed upper die and sliding the fixed upper die on a guide, a compression spring for the stripper, and a holder for the stripper And a pair of molds.The pair of molds positions the plate member punched by punching on the fixed lower mold and lowers the fixed upper mold to compress the slide lower mold. With spring force The end wall is formed by drawing, and the upper die is further lowered in the pressurized state. (The compression spring force of the lower die requires the force necessary to form the plate member into a predetermined shape. The condition is that it is weaker than the force with which the die moves down). A cylindrical body is formed by ironing with the outer periphery of the first stage of the die, and the fixed upper die descends to collide between the corner of the outer peripheral surface of the second stage of the fixed upper die and the fixed lower die surface. At this collision surface, a part of the cylindrical part was thinned and cutting occurred and the length of the cylindrical body was determined, then the fixed upper mold was raised and cut by the stripper and compression spring equipped on the outer periphery of the fixed upper mold. The plate member is an intermediate body by a method in which the cylindrical waste and the formed intermediate body are released from the mold. Manufacturing method of the rotor frame for claim 1 spindle motor according to the, and forming. 6. A method for manufacturing a rotor frame for a spindle motor, wherein the end wall portion, the annular protruding portion and the cylindrical portion are formed from one plate member according to claim 1, wherein one plate member is provided. Form a hollow cylindrical body by drawing and ironing it, and attach the hollow cylindrical body to a rotating device and rotate it while ironing the end wall with a roller or a fixed tool to make the wall thickness of the end wall By forming a thin wall, the outer peripheral portion of the free end is formed with a thinned protruding shape to form an annular protruding portion, and the end wall portion of this process product is punched into a square hole and the media guide portion is drawn. And a method for manufacturing a rotor frame for a spindle motor, characterized in that the rotor magnet restriction portion is subjected to a drawing process to be integrally formed.