JPH11342441A - Equipment and method for manufacturing shaft for dynamic pressure bearing, shaft for dynamic pressure manufactured by the method and dynamic pressure bearing motor using the shaft for dynamic pressure bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a dynamic pressure generating groove by rolling accurately at a low cost by providing a turning processing portion for a shaft material held in a main spindle and a rolling portion to rotate a round die by pressing and holding the shaft material between the round die and a pair of supporting rolls with mirror- finished surfaces arranged in two stages, up and down, in a rotating way. SOLUTION: A shaft material 1 held in a main spindle 2 and rotating is machined with a turning processing portion 6. The shaft material 1 is pressed and nipped between a round die 10 whose edge portion is formed by making a groove shape symmetrically to a prescribed dynamic pressure generating groove in a rolling portion 5 and a pair of supporting rolls 13a and 13b with mirror-finished surfaces arranged in two stages, up and down, in a rotating way, and is rolled by rotating the round die 10. This makes it possible to continuously perform all the processes to the completion of the shaft for a dynamic pressure bearing with a single equipment after the shaft material is installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for manufacturing a shaft for a dynamic pressure bearing having a groove for generating a dynamic pressure for generating a dynamic pressure, and a shaft for a dynamic pressure bearing manufactured by the manufacturing method. And a hydrodynamic bearing motor using the hydrodynamic bearing shaft.

[0002]

2. Description of the Related Art In recent years, in the field of motors, motors using dynamic pressure bearings for generating a dynamic pressure and supporting a rotating body have been widely used. This dynamic pressure bearing is used for gas such as air,
It is composed of a bearing using oil, a magnetic fluid, or the like as a dynamic pressure source and having a dynamic pressure generating groove formed in either the shaft or its receiving portion. Such a dynamic pressure bearing is known as a bearing that can easily realize a motor that is required to rotate precisely and at high speed. Specific examples of motors using hydrodynamic bearings include high-speed polygon scanner motors for optical scanning devices mounted on laser beam printers and digital copiers, and high-speed rotating scanners mounted on optical disk drives and hard disk drives. Type spindle motor and the like.

FIG. 7 shows a specific example of the above-described shaft for a dynamic pressure bearing and a groove for generating a dynamic pressure. FIG. 7A is a plan view showing the shape of a dynamic pressure generating groove formed on a shaft for a dynamic pressure bearing. FIG. 7B is a plan view showing another shape of the dynamic pressure generating groove formed on the dynamic pressure bearing shaft, and FIG. 7C is a dynamic pressure generating groove formed on the dynamic pressure bearing shaft. It is a top view showing other shapes of a slot. As shown in FIGS. 7A to 7C, on the outer peripheral surface 30a of the dynamic pressure bearing shaft 30, dynamic pressure generating grooves 31a, 3 each having a predetermined pattern shape are provided.
1b and 31c are provided. These dynamic pressure generating grooves 31a, 31b, 31c are known as a squeeze type, a herringbone type, and a spiral type, respectively, and are formed by cutting out the outer peripheral surface 30a of the dynamic pressure bearing shaft 30. Have been. In addition, the dynamic pressure bearing shaft 30 having the squeeze type and herringbone type dynamic pressure generating grooves 31a and 31b is provided with a dynamic central portion in the axial direction to stabilize the generated dynamic pressure. A pressure source, for example, an air introduction groove 32 for introducing air is provided.

The aforementioned dynamic pressure generating grooves 31a, 31b, 31
As a method of forming c on the outer peripheral surface 30a of the dynamic pressure bearing shaft 30, a known photolithography / etching method, a blast processing method using free abrasive grains, and a rolling processing method have been widely used. However, the photolithography / etching method requires expensive and dedicated manufacturing equipment such as a chemical treatment apparatus, and has the drawback of increasing the number of processing steps.
In addition, the blasting method requires special equipment such as a special device for preventing scattering of loose abrasive grains and processing the outer peripheral surface 30a, and further requires a post-processing step for removing attached abrasive grains. did. Further, in this blasting method, it is difficult to manage the shape of the dynamic pressure generating grooves 31a, 31b, 31c, for example, to control the groove depth. The work also took a long time. For this reason, in the conventional manufacturing apparatus and manufacturing method, it was common to manufacture a shaft for a dynamic pressure bearing using a rolling method.

Hereinafter, a conventional apparatus and method for manufacturing a shaft for a dynamic pressure bearing using a rolling method will be described in detail with reference to FIG. FIG. 8A is a structural view showing a schematic configuration of a conventional manufacturing apparatus of a shaft for a dynamic pressure bearing using a round die, and FIG. 8B is a conventional dynamic pressure bearing using a flat die. FIG. 2 is a structural diagram showing a schematic configuration of a manufacturing apparatus for a shaft. FIG. 8C is a structural view showing a schematic configuration of a conventional manufacturing apparatus for a shaft for a dynamic pressure bearing using balls.
The conventional apparatus for manufacturing a shaft for a dynamic pressure bearing shown in FIGS. 8A and 8B is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-7931.
No. 3 is disclosed.

As shown in FIG. 8A, a first conventional apparatus for manufacturing a shaft for a dynamic pressure bearing includes a round die 41 and a supporting roll 42 which are rotatably arranged, and these round dies. Bearing base 4 arranged between the die 41 and the supporting roll 42
3 is provided. Further, in the first conventional example, a shaft material 40 is rotatably disposed on a bearing base 43 between a round die 41 and a support roll 42. On the outer peripheral surface of the round die 41, a symmetrical shape is formed in the herringbone type or spiral type dynamic pressure generating grooves 31b and 31c (FIG. 7) to be formed. The shaft material 40 is
This is an intermediate material after a predetermined pre-processing step is performed by a processing device (not shown). More specifically, a stainless steel material is formed into a rod shape whose outer diameter and both end surfaces are finished by turning or grinding. It is a thing. In the first conventional example, the shaft material 40 is rotated by rotating the round die 41 and the support roll 42 in the directions of the arrows "D1" and "D2" in the figure, respectively.
By rotating in the direction of 3 ", herringbone type or spiral type dynamic pressure generating grooves 31b and 31c are formed on the outer peripheral surface of the shaft material 40. When this rolling is performed, a round die is used. The pressing force acting on the shaft material 40 from 41 is supported by a support roll 42 and a bearing base 43.

As shown in FIG. 8B, a second conventional example of a dynamic pressure bearing shaft manufacturing apparatus includes a flat die 44 and a support plate 45 slidably disposed in a predetermined direction. Have. Further, in the second conventional example, the shaft material 4 described above is used.
Numeral 0 is rotatably arranged between the flat die 44 and the support plate 45. On the surface of the flat die 44, similarly to the round die 41, a symmetrical shape is formed in the herringbone type or spiral type dynamic pressure generating grooves 31b and 31c to be formed. In the second conventional example, the flat die 44 and the support plate 45 are slid in the directions of arrows "H1" and "H2" in the figure, respectively, so that the shaft material 40 is moved in the direction of the arrow "D3" in the figure. , The herringbone type or spiral type dynamic pressure generating grooves 31b,
31 c is formed on the outer peripheral surface of the shaft material 40.

As shown in FIG. 8C, the third conventional apparatus for manufacturing a shaft for a dynamic pressure bearing is for forming a cylindrical ball holder 46 and grooves 31a to 31c for generating dynamic pressure. Are provided. In the third conventional example, after the ball 47 is pressed against the surface of the shaft material 40, the shaft material 40 and the ball 47 are moved into the hole 46a of the ball holder 46. Thereafter, the ball holder 46 is moved by the driving mechanism (not shown) to the arrow "H3" in the figure.
While moving the shaft material 40 in the direction of arrow "D3" in the figure.
Rotate in the direction of. Thereby, desired dynamic pressure generating grooves 3
1 a to 31 c are formed on the outer peripheral surface of the shaft material 40.

[0009]

The conventional apparatus and method for manufacturing a shaft for a dynamic pressure bearing using the above-described rolling method, as compared with the known photolithography / etching method and blast processing method. Shafts for dynamic pressure bearings have been manufactured using inexpensive and simple members such as dies or balls. For this reason, in the conventional manufacturing apparatus and manufacturing method, it is easier to reduce the cost of the shaft for the dynamic pressure bearing than using the photolithography / etching method and the blasting method. However, the conventional manufacturing apparatus and manufacturing method using this rolling method have the following problems (1) to (3). (1) Since the surface of the metal shaft material is subjected to plastic working to form the grooves for generating dynamic pressure, dedicated equipment with high rigidity capable of withstanding high contact pressure is required. (2) Due to variations in the outer diameter of the shaft material, etc., it may not be possible to form the dynamic pressure generating groove with high precision. After rolling, the groove is processed into an optimal shape for generating dynamic pressure. It was necessary to carry out a post-processing step for molding. (3) In the rolling process and the pre-processing process and the post-processing process to be performed before and after the rolling process, the shaft material is processed using different processing devices. It took time for additional adjustment work such as.

More specifically, in the first conventional example shown in FIG.
It is difficult to uniformly adjust the pressing force acting on the grooves, and when the pressing force changes, the dynamic pressure generating grooves 31b,
31c (FIG. 7) was apt to cause displacement. Further, in the first conventional example, the center position of the shaft material 40 on the bearing base 43 changes due to the variation in the outer diameter of the shaft material 40. Therefore, the dynamic pressure generating grooves 31b, 3
The depth dimension of 1c varied. Also, the bearing base 4
3 and the outer peripheral surface 40a of the shaft material 40 rub against each other under high pressure, so that the bearing base 43 was worn and the rotational position of the shaft material 40 on the bearing base 43 was lowered. As a result, the shapes of the dynamic pressure generating grooves 31b and 31c varied, and abrasion occurred on the outer peripheral surface 40a.

Further, in the second conventional example shown in FIG. 8B, since the shaft material 40 is not supported using the bearing base 43 unlike the first conventional example, the bearing base 43 The variation in the shape of the dynamic pressure generating grooves 31b and 31c due to the wear of the outer peripheral surface and the abrasion on the outer peripheral surface 40a do not occur. However, also in the second conventional example, similarly to the first conventional example, it is difficult to uniformly adjust the pressing force acting on the shaft material 40 from the flat die 44, and the pressing force is difficult. When the pressure changed, the dynamic pressure generating grooves 31b and 31c were apt to shift. Similarly, the center position of the shaft material 40 on the support plate 45 was changed due to the variation in the outer diameter of the shaft material 40. Therefore, the dynamic pressure generating grooves 31b, 3
The depth dimension of 1c varied. Furthermore, this second
In the conventional example, it is necessary to provide a support mechanism for rotatably supporting the shaft material 40 in synchronization with the sliding operation of the flat die 44 and the support plate 45, and the control and configuration of the manufacturing apparatus are complicated. It became.

Further, in the third conventional example shown in FIG. 8C, it is possible to reduce the pressing force acting on the shaft material 40 as compared with the first and second conventional examples. It was something. However, in the third conventional example, the positional relationship between the shaft material 40 and the ball 47 in the hole 46a of the ball holder 46 is accurately detected, and the movement of the ball holder 46 and the shaft material 40 is controlled. It was necessary to provide a position control mechanism to perform the operation. Further, in the third conventional example, the cross-sectional shape of the formed dynamic pressure generating grooves 31a to 31c is a round concave shape having substantially the same curvature as the ball,
No groove having a square concave cross section optimal for generating dynamic pressure could be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a dynamic pressure generating groove can be formed in a shaft material at low cost and with high precision by a rolling process. A manufacturing apparatus and a manufacturing method of a shaft for a dynamic pressure bearing capable of manufacturing a high quality shaft for a dynamic pressure bearing at low cost, and a shaft for a dynamic pressure bearing manufactured by the manufacturing method and the shaft for a dynamic pressure bearing. It is an object of the present invention to provide an improved dynamic bearing motor. Further, the present invention provides a manufacturing apparatus and a manufacturing method of a hydrodynamic bearing shaft that can be continuously performed from a material for the shaft to the completion of the hydrodynamic bearing shaft, and a hydrodynamic bearing shaft manufactured by the manufacturing method. It is an object of the present invention to provide a hydrodynamic bearing motor using the hydrodynamic bearing shaft.

[0014]

SUMMARY OF THE INVENTION According to the present invention, there is provided an apparatus for manufacturing a shaft for a dynamic pressure bearing, comprising: turning a spindle material held by a spindle material; and rotating the spindle material held by the spindle device. Turning part to apply, and a round die with a blade part formed by engraving a groove shape symmetrical to a predetermined dynamic pressure generating groove, the surface is machined to a mirror-finished state, and it is rotatably arranged in two upper and lower stages A pair of support rolls, and presses and clamps the shaft material held on the main spindle unit between the round die and the pair of support rolls to rotate the round die. It has a processing part. With this configuration, the dynamic pressure generating groove can be formed at low cost and with high precision in the shaft material.

According to another aspect of the present invention, there is provided an apparatus for manufacturing a shaft for a dynamic pressure bearing, comprising: a die holder for rotatably holding the round die; and a rotatably holding the pair of support rolls in a predetermined direction. A moving support roll slide unit, a brush slide unit having a rotary brush in contact with a shaft material held by the spindle spindle unit, holding the rotary brush rotatably, and moving in a predetermined direction; and A turning table, a die holder section, and a brush slide section are placed on the table, and the table moves in a predetermined direction.
With this configuration, the dynamic pressure generating groove can be formed at low cost and with high precision in the shaft material. Further, the process from the shaft material to the completion of the dynamic pressure bearing shaft can be continuously performed.

According to another aspect of the present invention, there is provided an apparatus for manufacturing a shaft for a dynamic pressure bearing, wherein the cross-sectional shape of the blade portion of the round die is a parallel shape in which the blade width at the tip and the blade width at the root are the same. Are trapezoidal in shape where the blade width is wider than the blade width at the tip. With this configuration, the groove for generating dynamic pressure can be formed on the outer peripheral surface of the shaft material without causing a deviation.

According to another aspect of the present invention, there is provided an apparatus for manufacturing a shaft for a dynamic pressure bearing, wherein an outer peripheral speed of the round die is equal to a peripheral speed of a groove bottom surface of the shaft material formed by the blade portion. The round die and the shaft material are configured to rotate. With this configuration, the dynamic pressure generating groove can be formed at low cost and with high precision in the shaft material.

According to another aspect of the present invention, there is provided an apparatus for manufacturing a shaft for a dynamic pressure bearing, wherein the dynamic pressure generating groove has a herringbone type.
The shape is either a spiral type or a squeeze type. With this configuration, the dynamic pressure generating groove having any of the above shapes can be formed on the shaft material with low cost and high accuracy.

According to another aspect of the invention, there is provided an apparatus for manufacturing a shaft for a dynamic pressure bearing, wherein the pair of support rolls has an angle formed between the center of the shaft material and the center of the pair of support rolls of 90 to 120 degrees. Is held within the range.
With this configuration, the dynamic pressure generating groove can be formed at low cost and with high precision in the shaft material.

In the method of manufacturing a shaft for a dynamic pressure bearing according to the present invention, a turning step of turning the shaft material held and rotated by the spindle spindle portion, and holding and rotating by the spindle shaft portion. The shaft material was engraved with a groove shape symmetrical to a predetermined dynamic pressure generation groove and a round die with a blade was formed. The surface was machined to a mirror-finished state, and it was rotatably arranged in two stages up and down. A rolling process is provided in which the shaft material is rolled by being pressed and held between a pair of support rolls and rotating the round die. With this configuration, the dynamic pressure generating groove can be formed at low cost and with high precision in the shaft material. further,
It is possible to manufacture a high-quality, low-cost hydrodynamic bearing motor manufactured by this manufacturing method and a hydrodynamic bearing motor having a bearing portion using the hydrodynamic bearing shaft.

According to another aspect of the invention, there is provided a method of manufacturing a shaft for a dynamic pressure bearing, wherein in the rolling step, the pair of support rolls is formed by an angle formed between a center of the shaft material and a center of the pair of support rolls. Is held in the range of 90 degrees or more and 120 degrees or less. With this configuration, the dynamic pressure generating groove can be formed at low cost and with high precision in the shaft material.

According to another aspect of the present invention, there is provided a method of manufacturing a shaft for a dynamic pressure bearing, wherein in the rolling step, the outer peripheral speed of the round die and the peripheral speed of the bottom surface of the groove of the shaft material formed by the blade portion. The round dies and the shaft material are rotated so that? With this configuration, the dynamic pressure generating groove can be formed at low cost and with high precision in the shaft material.

According to another aspect of the present invention, there is provided a method of manufacturing a shaft for a dynamic pressure bearing, wherein a cross-sectional shape of the blade portion of the round die is a parallel shape or a root where a blade width at a tip and a blade width at a root are the same. Are trapezoidal in shape where the blade width is wider than the blade width at the tip. With this configuration, the groove for generating dynamic pressure can be formed on the outer peripheral surface of the shaft material without causing a deviation.

According to another aspect of the invention, there is provided a method of manufacturing a shaft for a dynamic pressure bearing, wherein the dynamic pressure generating groove has a herringbone type.
The shape is either a spiral type or a squeeze type. With this configuration, the dynamic pressure generating groove having any of the above shapes can be formed on the shaft material with low cost and high accuracy.

According to another aspect of the present invention, there is provided a method of manufacturing a shaft for a dynamic pressure bearing, wherein a turning process is performed for turning a shaft material held and rotated by a spindle unit, and the shaft material is held and rotated by the spindle unit. The shaft material is engraved with a groove that is symmetrical to the predetermined dynamic pressure generating groove, and a round die with a blade is formed. Rolling process for rolling the shaft material by pressing and holding it between the pair of support rolls, and rotating the round die is held and rotated by the spindle unit. A finishing step of finishing the shaft material into a predetermined shape; and a removing step of removing burrs of the rotating shaft material held and rotated by the main spindle unit. With this configuration, the dynamic pressure generating groove can be formed at low cost and with high precision in the shaft material. Further, the process from the shaft material to the completion of the dynamic pressure bearing shaft can be continuously performed. In addition, it is possible to manufacture a high-quality and low-cost hydrodynamic bearing motor manufactured by this manufacturing method and a hydrodynamic bearing motor including a bearing portion using the hydrodynamic bearing shaft.

In a method of manufacturing a shaft for a dynamic pressure bearing according to another aspect of the present invention, the burr is removed by a brushing method using a rotary brush in the removing step. With this configuration, the dynamic pressure generating groove can be formed at low cost and with high precision in the shaft material.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

Embodiment [Structure of Manufacturing Apparatus] FIG. 1 is a structural diagram showing a schematic structure of a manufacturing apparatus of a shaft for a dynamic pressure bearing according to the present invention. FIG. 2 is an enlarged perspective view illustrating a configuration of a main part of the rolled processing section illustrated in FIG. 1. As shown in FIG. 1, the apparatus for manufacturing a shaft for a dynamic pressure bearing according to the present embodiment includes a spindle 1, a die holder 3, and a support roll slide 4, which hold a shaft material 1 by chucking and rotate. In addition, a rolling section 5 for forming a desired dynamic pressure generating groove in the shaft blank 1 and a turning section 6 for turning the shaft blank 1 are provided. Further, the manufacturing apparatus of the present embodiment includes a rotary brush 7 for removing burrs generated on the shaft material 1, and a brush slide portion 8 that holds and moves the rotary brush 7,
The table 9 includes an X table 9a and a Z table 9b that can be moved in the directions of the arrows “X” and “Z” in the figure, respectively.

The shaft material 1 has a length of, for example, 30 m.
m, a cylindrical metal member having a diameter of about 8 to 15 mm,
A groove for generating dynamic pressure is formed on the outer peripheral surface (cylindrical surface), and is processed and manufactured into a shaft for dynamic pressure bearing. Using the manufacturing apparatus of the present example, the results of verification of the machinability and rolling properties and the rigidity as a shaft for a dynamic pressure bearing, etc., show that metal members such as aluminum, brass, and stainless steel can be used as the shaft material 1. confirmed. In the following description, a case in which a shaft for a dynamic pressure bearing is manufactured from aluminum shaft material 1 will be described. The spindle 2 has a spindle motor 2a and a spindle 2 for transmitting the power of the spindle motor 2a.
b, and a chuck portion 2c attached to the spindle 2b and chucking and holding the shaft material 1.
After inserting and mounting the shaft material 1 into the chuck portion 2c, the main spindle portion 2 holds the shaft material 1 until the manufacture of the dynamic pressure bearing shaft is completed. The spindle motor 2
Due to the rotation of a, the shaft material 1 becomes, for example, an arrow "R"
It rotates together with the chuck 2c in the direction of 1 ".

The die holder 3 is a round die 1 having a concave and convex shape for forming a groove for generating dynamic pressure formed on the outer peripheral surface.
A die holder 11 for rotatably holding the round die 10; and a die motor 12 for rotating the round die 10. The round die 10 is connected to a die motor 12 via a gear (not shown),
Due to the rotational force from the dice motor 12, it rotates, for example, in the direction of arrow "R2" in the figure. The round die 10 is configured to be separable from the gear, and is set on the die holder 11 so as to be able to rotate without receiving the above-mentioned rotational force, for example, also by a frictional force generated by rotation of the shaft material 1 that has come into contact therewith. The dice motor 12 is fixed on the X table 9a, and the X table 9a and the Z table 9
It is moved in two directions by the operation of b. The support roll slide unit 4 includes a pair of support rolls 13a and 13b arranged in two stages, and a pair of the support rolls 13a and 13b.
And a roll moving mechanism 15 to which the roll holder 14 is attached. The roll moving mechanism 15 is composed of a known member such as a motor, and moves the roll holder 14 in the direction of the arrow “S1” in the figure. The support rolls 13a and 13b not only support the shaft material 1 during the rolling process, but also come into contact with the surface of the shaft material 1 in which the dynamic pressure generating grooves are formed, and return and level the surface portion. (Details will be described later).

When a rolling process for forming a groove for generating a dynamic pressure in the shaft material 1 is performed, the rolling portion 5 including the die holder portion 3 and the supporting roll slide portion 4 is formed as shown in FIG. X table 9a and roll moving mechanism 15
, Respectively, the shaft material 1 is moved and arranged so as to press and hold the shaft material 1 with a predetermined pressure by the round die 10 and the pair of support rolls 13a and 13b.
Furthermore, in this rolling process, the round die 10 is rotated at an outer peripheral speed that matches the peripheral speed of the groove bottom surface of the shaft blank 1 formed by the outer peripheral surface of the round die 10. Thus, in the manufacturing apparatus of the present embodiment, it is possible to prevent the occurrence of a deviation in the groove shape and accurately form the dynamic pressure generating groove on the outer peripheral surface of the shaft material 1. The shaft material 1 shown in FIG. 2 has one end portion chucked by the chuck portion 2c (FIG. 1). In the turning process performed before the rolling process, It is formed and processed to the required predetermined shape and dimensions. More specifically, the outer peripheral surface and outer diameter of the shaft material 1 are formed in predetermined shapes and dimensions, and a dynamic pressure source, for example, an air introduction groove for introducing air is formed on the outer peripheral surface. .

Here, referring to FIG.
Will be described in more detail. FIG. 3A is a plan view showing the configuration of a round die viewed from the outer peripheral surface side.
(B) is a front view showing a configuration of a round die. FIG.
(C) is an enlarged view of the detailed configuration of the portion surrounded by the solid line A in (b) of FIG. 3, and (d) of FIG.
It is sectional drawing which shows the cross section of the round die which took the cross section by the Id-IIId line. 3 (a) to 3 (d),
The round die 10 is a metal member having a diameter of, for example, 60 mm, and has a Rockwell-type hardness on a C scale (H
RC) is 60 degrees or more (for example, SKD-1)
1). On the outer peripheral surface of the round die 10, an irregular shape symmetrical to the shape of the groove for generating dynamic pressure is engraved,
A blade portion 10a having a predetermined pattern shape is formed. Die holder 11 (Fig. 1)
Is provided with a hole 10b. still,
The pattern shape of the blade portion 10a shown in FIG. 3A is a shape for forming a herringbone type dynamic pressure generating groove. By setting a round die provided with a blade having a pattern shape different from this shape in the die holder 11, the manufacturing apparatus of the present embodiment can generate, for example, a spiral dynamic pressure generation shown in FIG. The groove for the shaft can be formed on the outer peripheral surface of the shaft material.

As shown in FIG. 3C, the shape of the blade portion 10a is such that the blade width at the base of the convex portion (shown by "H") is the blade width at the tip of the convex portion (shown by "h"). The cross-sectional shape is configured to be a tapered trapezoid so as to be at least larger.
The reason is that the shape of the groove for generating dynamic pressure is generally preferably such that the angle formed between the side surface of the groove and the outer peripheral surface is in the vicinity of 90 degrees from the viewpoint of the efficiency of generating the dynamic pressure. However,
After the grooves for generating dynamic pressure are formed by the round dies 10, the shaft material 1 is formed by a pair of support rolls 13a and 13b (FIG. 2).
In the manufacturing apparatus of this embodiment for performing the return and leveling of the outer peripheral surface of FIG. 2, when the shape of the blade portion 10a is configured to satisfy the relationship of H <h, the return and leveling by the support rolls 13a and 13b. By virtue of the action, the dynamic pressure generating groove is easily formed in an overhang shape. Further, the round die 10 having the non-tapered trapezoidal blade portion 10a requires a high pressing force at the time of rolling. On the other hand, H
When the shape of the blade portion 10a is configured to satisfy the relationship of ≧ h, the dynamic pressure generating groove is formed in an optimal shape by the above-described returning and leveling action, and furthermore, the pressing force at the time of the rolling process is reduced. Can be reduced. In the production of the round die 10 as well, by making the cross-sectional shape of the blade portion 10a a tapered trapezoid, it can be easily produced using a general gear processing machine or gear grinding machine. In addition, as shown in FIG. 3D, when the circular die 10 is formed by combining two cylindrical members 10c and 10c ', the manufacture thereof can be further facilitated.

Returning to FIG. 2, a pair of support rolls 13a,
13b is a cylindrical metal member having a diameter of, for example, 20 mm, and is made of a metal (for example, SKD-11) having a hardness of HRC 60 degrees or more. The surfaces of these support rolls 13a and 13b are processed into a mirror-finished state, and are rotatably mounted on the roll holder 14 so that their respective central axes are parallel to each other.
These support rolls 13a and 13b press against the shaft material 1 and rotate by the frictional force. The mounting position of the support rolls 13a and 13b is determined by the angle ("") between the center of the shaft blank 1 and the center of the support rolls 13a and 13b.
θ ”) is desirably in the range of 90 ° to 120 ° because, as shown in FIG. Further, according to the verification results of the inventors, the angle θ
Is larger than 120 degrees, the support roll 13
The efficiency of the later-described return and leveling of the surface of the shaft material 1 applied by the a and 13b is reduced. On the other hand, when the angle θ was set to be smaller than 90 degrees, the manufacturing accuracy and the manufacturing efficiency of the groove for generating dynamic pressure were reduced.

Here, a pair of support rolls 13a, 13b
The action of the return and the smoothing by the following will be described. In the rolling process, the shaft blank 1 receives the pressing force from three directions of the round die 10 and the support rolls 13a and 13b, and the convex blade 10a engraved on the surface of the round die 10 is formed. A concave-shaped groove for generating dynamic pressure is formed on the surface of the shaft material 1. In the step of forming the recessed dynamic pressure generating groove by the round die 10, in the surface portion of the shaft material 1,
A bulging deformation having an amount close to the volume change amount of the concave portion is formed as a convex portion around the concave portion. As a result, in the shaft material 1, the above-described protrusions protrude outward, and the cross-sectional shape of the shaft material 1 does not become circular. That is, the quality of the shaft for a dynamic pressure bearing is reduced. However, in the manufacturing apparatus of the present embodiment, the pair of support rolls 13a and 13b press the surface of the shaft material 1. As a result, the surface portion of the shaft material 1 is formed by a pair of support rolls 13a and 13b.
The amount of return to the concave portion during the process of passing through and the amount absorbed by the change in material density reduce the amount of protrusion of the convex portion, and the outer diameter of the shaft material 1 substantially returns to the original size. Further, the concave portion is formed as a groove capable of generating a dynamic pressure while slightly changing the shape. As described above, in the manufacturing apparatus according to the present embodiment, the step of forming the concave-shaped dynamic pressure generating groove by the round die 10 and the step of returning and leveling the swelling by the support rolls 13a and 13b are repeated a plurality of times.
A groove having sufficient accuracy and shape for a dynamic pressure bearing can be formed on the outer peripheral surface of the shaft material 1.

Returning to FIG. 1, the turning section 6 includes a plurality of blades 16 for performing turning on the shaft blank 1 and a blade holder 17 fixed to the X table 9a and holding the above-described blade 16. Have. The plurality of blades 16 are prepared in advance according to the specifications of the shaft for the dynamic pressure bearing to be manufactured. Specifically, the cutting tool 16 includes a parting-off tool 16a, a single-edge tool 16b, a serious tool 16c, and a drill 16d shown in FIGS. 4A to 4D, respectively. Parting off tool 16a, single edge tool 16
The b and the serious cutting tool 16c are provided with a blade 16e for making contact with the surface of the shaft material 1 and shaving the surface. The drill 16d is used for an operation of forming a hole in the shaft material 1. The blade holder 17 is fixed on the X table 9a, and is moved in two directions by the operation of the X table 9a and the Z table 9b. The brush slide section 8
A rotatable brush 7 rotatable as indicated by an arrow "R3" in the figure, and a brush holder 1 holding the rotatable brush 7
8 and a brush moving mechanism 19 to which a brush holder 18 is attached. The rotary brush 7 comes into contact with the surface of the shaft material 1 held by the main spindle 2 and removes unnecessary portions such as burrs generated on the surface. The rotary brush 7 is formed of plastic, animal hair, or a mixture thereof. The brush-brush moving mechanism 19 is composed of a known member such as a motor, and moves the brush holder 18 in the direction of arrow "S2" in the figure. The table 9 includes an X table 9a on which the die holder 3, the turning part 6, and the brush slide 8 are mounted, and a Z table 9b on which the X table 9a is mounted. The X table 9a is an X-axis motor 20a
The Z table 9b is moved in the direction of the arrow "X" in the figure by the operation of the arrow.
Move in the Z ″ direction.

[Operation of Manufacturing Apparatus] The operation of the apparatus for manufacturing a hydrodynamic bearing shaft according to the present embodiment will be described below with reference to FIG. FIG. 5 is an explanatory view showing the operation of the manufacturing apparatus shown in FIG. 1, and the steps of manufacturing the shaft for a dynamic pressure bearing are performed in the order of (a) to (e). As shown in FIG. 5A, first, the shaft material 1 is inserted into the chuck portion 2c (FIG. 1) of the spindle spindle portion 2 (FIG. 1) and mounted. Chuck 2c
The position of the shaft material 1 chucked by
Is shown in FIG. The chuck holding state of the shaft material 1 is maintained until the manufacture of the dynamic pressure bearing shaft 21 is completed, as shown in FIGS. 5 (a) to 5 (e). Shaft material 1
Is a short product having a length dimension of less than 500 mm, and 5
Any material of a long product having a length of 00 mm or more can be processed. However, in the case of a long product, the chucking force at the chuck portion 2c is increased and the shaft with respect to the main spindle 2 is increased. It is desirable to take measures such as steadying the material 1.

Next, the spindle material 1 is rotated by the spindle 2 and a turning process is performed on the shaft material 1 using the blade 16 (FIG. 1) on the X table 9a (FIG. 1). As a result of this turning process, as shown in FIG. 5B, the shaft material 1 has an outer peripheral surface 21a and an air introduction groove 21 having the shape and dimensions required in the subsequent rolling process.
b is formed. For example, when it is necessary to provide a communication hole for communicating the end face of the shaft material 1 with the air introduction groove 21b inside the shaft material 1 in a direction parallel to the axial direction, the drilling is performed by the diameter of the communication hole. However, it is desirable to perform it after performing the next rolling process. This is because, if a communication hole is provided by performing a perforation process before the rolling process, the communication hole may be deformed.

Subsequently, the turning blade 16 in the previous step is retracted backward, and the shaft material 1 is fixed to a predetermined shape by the round die 10 (FIG. 2) and the pair of support rolls 13a and 13b (FIG. 2). A rolling process is performed in which the spindle material 2 is rotated by the main spindle 2 while being pressed and held by pressure. As a result of this rolling process, as shown in FIG. 5C, a groove 21c for generating dynamic pressure is formed on the outer peripheral surface 21a. In this rolling process, the outer peripheral speed of the round die 10 is made to coincide with the peripheral speed of the bottom of the concave groove of the shaft material 1 so that the round die 1
0 and the shaft material 1 are rotating. Accordingly, even if the shaft material 1 is rotated a plurality of times, there is no deviation in the groove shape, and the grooves necessary for generating the dynamic pressure can be accurately obtained during the plurality of rotations. At the same time, on the outer surface of the shaft material 1, the convex portion between the formed grooves is smoothed by a pair of support rolls 13 a and 13 b into a smooth cylindrical surface (outer peripheral surface). As a result, finishing of the dynamic pressure generating groove 21c can be omitted.

Next, after the round die 10 and the pair of support rolls 13a and 13b of the preceding process have been retracted backward, as shown in FIG.
A finishing step of turning and finishing the outer peripheral surface 21a into a predetermined shape and a removing step of removing a burr of the shaft material 1 are performed. Specifically, after performing the turning process and the hole forming process using the blade 16, the rotating rotary brush 7 is pressed against the outer peripheral surface 21 a of the shaft material 1, and the burrs at the cutting corners are removed. Remove. Subsequently, as shown in FIG. 5E, a cutting / turning step of separating the completed hydrodynamic bearing shaft 21 is performed using the parting tool 16a (FIG. 4) included in the blade 16. After the cutting and turning process, the remaining shaft material 1 is released from the chuck and pushed out from behind.

Here, with reference to FIGS. 6A to 6C, in the rolling process in the apparatus for manufacturing a shaft for a dynamic pressure bearing of the present embodiment, the shaft material 1 and the round Verification results obtained by verifying the shape of the groove for generating dynamic pressure when the rotational operation of the die 10 is changed will be described. FIG. 6A is a measurement result showing a cross section of the shaft for a dynamic pressure bearing when the shaft material and the round die are rotated at the same rotation speed. FIG. 6B is a measurement result showing a cross section of the shaft for a dynamic pressure bearing when the circular die is rotated by applying a rotational force only, and FIG. 6C shows a rotational force only to the shaft material. 5 is a measurement result showing a cross section of a shaft for a dynamic pressure bearing when the shaft is rotated with the rotation of the shaft. FIG.
(A) to (c) of FIG. 6 are the results of measuring the cross section of the shaft for a dynamic pressure bearing using a roundness measuring device (manufactured by Taylor Hobson). It shows a reference perfect circle displayed on the measurement result of the circularity measuring device. As shown in FIG. 6A, the outer peripheral speed of the round die 10 is adjusted to match the peripheral speed of the bottom surface of the concave groove of the shaft material 1, and the round die 10 and a pair of support rolls 13a, 13b
When the shaft material 1 is rotated three times between the two, the outer peripheral surface 21a of the dynamic pressure bearing shaft 21 is formed smoothly, and the dynamic pressure generating groove 21c is also formed substantially uniformly.

As shown in FIG. 6 (b), when the shaft material 1 is rotated three times only by the round die 10 without rotating the shaft material 1 by the main spindle unit 2, the dynamic bearing is used. Irregularities occur on the outer peripheral surface 22a of the shaft 22, and the dynamic pressure generating grooves 22c are not uniformly formed. FIG. 6 (c)
As shown in FIG. 3, when the shaft material 1 is rotated three times without rotating the round die 10 by the die motor 12, the dynamic pressure generating groove 23c formed on the outer peripheral surface 23a of the dynamic pressure bearing shaft 23. Has a displacement phenomenon. According to the experiments conducted by the inventors, the above-described displacement phenomenon differs depending on the material of the shaft material 1. Aluminum is easily generated and stainless steel is hardly generated. Further, according to experiments by the inventors, it has been confirmed that the occurrence of the above-described displacement phenomenon can be prevented by adjusting the ratio of the outer diameter of the shaft material 1 to the outer diameter of the round die 10. However, as in the manufacturing apparatus of the present embodiment, the method of rotating the peripheral speed of the round die 10 so that the peripheral speed of the groove bottom surface of the shaft material 1 matches the peripheral speed of the round die 10 is as follows.
Even if there is some variation in the outer diameter of the shaft material 1,
The occurrence of the displacement phenomenon was reliably prevented, and the shape of the dynamic pressure generating groove was made uniform.

[0043]

As described above, according to the manufacturing apparatus and the manufacturing method of the shaft for a dynamic pressure bearing of the present invention, after the shaft material is mounted and the chuck is held, the entire process from the completion of the shaft for the dynamic pressure bearing to the completion is completed. The manufacturing process can be performed continuously using a single facility.
As a result, in the apparatus and method for manufacturing a shaft for a dynamic pressure bearing of the present invention, the accuracy required for the shaft for a dynamic pressure bearing can be easily realized, and further, the number of steps, the equipment cost, and the rolling process The time required for processing can be greatly reduced by using. As a result, according to the apparatus and method for manufacturing a shaft for a dynamic pressure bearing of the present invention, it is possible to form the dynamic pressure generating groove in the shaft material with high precision at low cost. Furthermore, by making the convex shape of the round die into a tapered trapezoidal shape, the pressure acting on the shaft material during rolling can be reduced, and the round die can be easily manufactured. Further, a dynamic pressure bearing shaft manufactured by the manufacturing apparatus and the manufacturing method of the dynamic pressure bearing shaft of the present invention, and a dynamic pressure bearing motor in which a bearing portion is configured using the dynamic pressure bearing shaft are also obtained as a result. It can be inexpensive and of high quality.

[Brief description of the drawings]

FIG. 1 is a structural view showing a schematic configuration of a manufacturing apparatus of a shaft for a dynamic pressure bearing of the present invention.

FIG. 2 is an enlarged perspective view showing a configuration of a main part of a rolled processing part shown in FIG. 1;

FIG. 3 is an enlarged structural view showing a configuration of a round die shown in FIG. 1;

FIG. 4 is an enlarged perspective view illustrating a configuration of a specific example of the blade illustrated in FIG. 1;

FIG. 5 is an explanatory diagram showing the operation of the manufacturing apparatus shown in FIG.

FIG. 6 is a measurement result showing a cross section of a shaft for a dynamic pressure bearing in which a groove for generating a dynamic pressure is formed.

FIG. 7 is a plan view showing the shape of a dynamic pressure generating groove formed on a shaft for a dynamic pressure bearing.

FIG. 8 is a structural view showing a schematic configuration of a conventional manufacturing apparatus for a shaft for a dynamic pressure bearing.

[Explanation of symbols]

 Reference Signs List 1 shaft material 2 spindle spindle section 3 die holder section 4 support roll slide section 5 rolling section 6 turning section 7 rotary brush 8 brush slide section 9a, 9b table 10 round die 10a blade section 13a, 13b support roll 21c Groove for generating dynamic pressure

Continuation of the front page (72) Inventor Kenichi Watanabe 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (17)

[Claims] 1. A spindle unit which rotates while holding a shaft material, a turning unit which performs a turning process on the shaft material held by the spindle unit, and a predetermined dynamic pressure generating groove. A round die having a groove formed and a blade portion formed, and a pair of support rolls whose surfaces are processed into a mirror-finished state and which are rotatably arranged in two upper and lower stages. Manufacturing a shaft for a hydrodynamic bearing, comprising: a rolling part for rotating the round die by pressing and holding the material for the shaft held by the main spindle portion between the support roll and the support roll. apparatus. 2. A die holder for rotatably holding the round die, a support roll slide for rotatably holding the pair of support rolls and moving in a predetermined direction, and a holder for the main spindle. A rotary brush that is in contact with the shaft material, and holds the rotary brush rotatably and moves in a predetermined direction, and a brush slide portion, and the turning portion, a die holder portion, and a brush slide portion. The apparatus for manufacturing a shaft for a hydrodynamic bearing according to claim 1, further comprising a table mounted and moved in a predetermined direction. 3. The cross-sectional shape of the blade portion of the round die is a parallel shape in which the tip blade width and the root blade width are the same size, or a trapezoidal shape in which the root blade width is wider than the tip blade width. The apparatus for manufacturing a shaft for a dynamic pressure bearing according to claim 1 or 2, wherein 4. The round die and the shaft material are rotated so that an outer peripheral speed of the round die and a peripheral speed of a groove bottom surface of the shaft material formed by the blade portion match. 4. The method according to claim 1, wherein
The manufacturing apparatus for a shaft for a dynamic pressure bearing according to any one of the above. 5. The dynamic pressure generating groove according to claim 1, wherein the dynamic pressure generating groove has one of a herringbone type, a spiral type, and a squeeze type. Equipment for manufacturing shafts for pressure bearings. 6. An angle between the center of the shaft material and the center of the pair of support rolls is 90.
The apparatus for manufacturing a shaft for a hydrodynamic bearing according to any one of claims 1 to 4, wherein the shaft is held so as to be within a range of not less than 120 degrees and not more than 120 degrees. 7. A turning process for turning a shaft material held and rotated by a spindle spindle portion, and a shaft material held and rotated by the spindle spindle portion for generating a predetermined dynamic pressure. Pressing and pinching between a round die with engraved groove shape symmetrical to the groove to form a blade, and a pair of support rolls whose surface is machined to a mirror-finished state and which is rotatable up and down two steps And a rolling step of rolling the shaft material by rotating the round die. 8. In the rolling process, the pair of support rolls is formed such that an angle formed between a center of the shaft material and a center of the pair of support rolls is in a range of 90 degrees or more and 120 degrees or less. The method according to claim 7, wherein the shaft is held. 9. The rolling die and the shaft so that the outer peripheral speed of the round die and the peripheral speed of the groove bottom surface of the shaft material formed by the blade portion match in the rolling process. The method for manufacturing a shaft for a dynamic pressure bearing according to claim 7, wherein the material for rotation is rotated. 10. A sectional shape of a blade portion of the round die,
The shaft for a hydrodynamic bearing according to claim 7, wherein the blade width at the tip is a parallel shape having the same dimension as the blade width at the root, or a trapezoidal shape having a blade width at the root wider than the blade width at the tip. Production method. 11. The method for manufacturing a shaft for a dynamic pressure bearing according to claim 7, wherein the shape of the dynamic pressure generating groove is any one of a herringbone type, a spiral type, and a squeeze type. . 12. A shaft for a dynamic pressure bearing, wherein a groove for generating a dynamic pressure is formed by the manufacturing method according to any one of claims 7 to 11. 13. A dynamic pressure bearing, wherein a bearing portion is formed by using a shaft on which a dynamic pressure generating groove is formed by the manufacturing method according to any one of claims 7 to 11. motor. 14. A turning step of performing turning on a shaft material held and rotated by a main spindle spindle portion, wherein the shaft material held and rotated by the main spindle portion is formed into a predetermined dynamic pressure generating groove. It is pressed and sandwiched between a round die with a groove formed symmetrically to the edge and a blade part, and a pair of support rolls that are machined to a mirror-finished surface and that are rotatably arranged in two upper and lower stages. A rolling process of rolling the shaft material by rotating the round die; a finishing process of finishing the rotating shaft material held by the main spindle unit into a predetermined shape; and A method for manufacturing a shaft for a dynamic pressure bearing, comprising a removing step of removing burrs of a shaft material held and rotating by the spindle unit. 15. The method according to claim 14, wherein, in the removing step, the burrs are removed by a brushing method using a rotary brush. 16. A dynamic pressure bearing shaft, wherein a groove for generating dynamic pressure is formed by the manufacturing method according to claim 14. Description: 17. A method according to claim 14, wherein a shaft having a dynamic pressure generating groove formed therein is used.
A hydrodynamic bearing motor comprising a bearing portion.