JP2004324684A - Method for manufacturing dynamic pressure generating groove - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a dynamic pressure generating groove for providing a dynamic pressure bearing to set a gap between a shaft member as an integrated body of a shaft with a flange part and an inner circumferential surface of a sleeve in a desired state after formation of the dynamic pressure generating groove even when there is residual internal stress in a case where drawn material is used. <P>SOLUTION: The dynamic generating groove is formed by plastic work in the surface of a flange part of the dynamic pressure bearing composed of the shaft member 1 comprising a shaft part 2 and a flange part 3, and a sleeve having a gap to the shaft part 2 and the flange part 3 for the shaft member 1 to be engaged. The shaft member 1 is formed by lathing of drawn material of which drawn direction is known. The shaft member is taken correctly as sized, the dynamic pressure generating groove is formed in the surface of the flange part, perpendicular distance from an outer circumferential end part of the flange part to the shaft part is measured, an obtained value is fed back to take the shaft member from the drawn material, and plastic work is performed to the flange part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

この表１に示すように、引き抜き材から旋削加工により取り出した軸部材１は、その残留応力の影響を考慮して、フィードバックしてフランジ部３を形成すれば、軸部２とフランジ部３とが ほぼ正確な直角度を有する軸部材１とすることができることが判明した。
【００２２】
【発明の効果】
以上、詳述したように、本発明の動圧発生用溝の製造方法によれば、ステンレス鋼や炭素鋼等の引き抜き材を使用する場合、内部に残留応力が存在してプレス加工のような塑性加工により動圧発生用溝を加工した後の軸とフランジ部とを一体とした軸部材とスリーブ内周面との間の隙間が意図したとおりの正確な動圧軸受を得ることができる。また、本発明の製造方法によれば、スリーブやスラスト板等に動圧発生用溝の煩雑な加工が不要となる。更に、軸に設けたフランジ部の上下両面に同時に同じ動圧発生用溝を加工することができるので工程数を低減することができる。また、軸に設けたフランジ部の上下両面に動圧発生用溝を加工する場合、同じ形状の動圧発生用溝が安定的に得られるので、組立完了後の精度が良くなり、不良品発生率も低下しその分製造コストを低減することができる。
【図面の簡単な説明】
【図１】本発明の動圧発生用溝の製造方法を実施するに際して軸部材を取り出す前の冷間引き抜き加工材を示す図である。
【図２】Ｔ字形の軸部材を取り出すとき、予めプレス加工した結果を考慮して逆方向に生じた歪の角度分傾斜した状態で旋削加工した軸部材を示す図である。
【図３】図３（Ａ）は、予めプレス加工した結果を考慮して逆方向に生じた歪の角度分傾斜した状態で旋削加工した軸部材をプレス加工した状態の軸部材を示す図であり、図３（Ｂ）は、この軸部材をスリーブに嵌め入れた状態の断面図である。
【図４】引き抜き材から取り出した軸部材のフランジ部の内径部から外径部（外周端部）にかけて肉厚が薄くなるように形成する場合であって、図４（Ａ）は、プレス加工前の状態を示す一部断面図であり、図４（Ｂ）は、付パス加工後の状態を示す一部断面図である。
【図５】引き抜き材から取り出した軸部材のフランジ部の内径部から外径部（外周端部）にかけて肉厚が薄くなるように形成する場合であって、図５（Ａ）は、プレス加工前の状態を示す一部断面図であり、図５（Ｂ）は、プレス加工後の状態を示す一部断面図である。
【図６】引き抜き材から取り出した軸部材のフランジ部の内径部から外径部（外周端部）にかけて肉厚が厚くなるように形成する場合であって、図６（Ａ）は、プレス加工前の状態を示す一部断面図であり、図６（Ｂ）は、付パス加工後の状態を示す一部断面図である。
【図７】引き抜き材から取り出した軸部材のフランジ部の内径部から外径部（外周端部）にかけて肉厚が厚くなるように形成する場合であって、図７（Ａ）は、プレス加工前の状態を示す一部断面図であり、図７（Ｂ）は、プレス加工後の状態を示す一部断面図である。
【図８】冷間引き抜き加工材から旋削加工により取り出した軸部とフランジ部からなるＴ字形の軸部材を示す図である。
【図９】冷間引き抜き加工材から旋削加工により取り出した軸部材のフランジ部に動圧発生用溝を形成するためのプレス加工する状態を示す図である。
【図１０】冷間引き抜き加工材から旋削加工により取り出した軸部材のフランジ部に動圧発生用溝を形成するためプレス加工した状態を示す図である。
【図１１】冷間引き抜き加工材から旋削加工により取り出した軸部材のフランジ部に動圧発生用溝を形成した後この軸部材をスリーブに嵌め入れた状態の動圧軸受の断面図を示す図である。
【符号の説明】
１ 軸部材
２ 軸部
３ フランジ部
４ 動圧発生用溝[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a hydrodynamic bearing comprising a shaft member having a flange integrally formed on a shaft and a sleeve having a slight gap between the shaft portion and the flange portion. The method for producing the dynamic pressure generating groove when forming the dynamic pressure generating groove by the method described above, in particular, a dynamic method capable of making the gap between the flange portion of the shaft member using the drawn material and the sleeve axial surface almost uniform. The present invention relates to a method for manufacturing a pressure generating groove.
[0002]
[Prior art]
A shaft member integrally formed with a shaft portion and a flange portion used as a dynamic pressure bearing may be formed by turning and then plastically processing a dynamic pressure generating groove formed on the flange portion surface by a press or the like. . For example, a dynamic pressure bearing may be used for a spindle motor. In this case, a dynamic pressure bearing on a surface of a disk-shaped bearing member formed on a rotating shaft is manufactured by press working (Patent Document 1). . Also, when processing the dynamic pressure generating groove by plastic deformation such as press working, the inner circumference of the flange portion is formed one step lower than the outer side, the dynamic pressure generating groove is formed on the outer circumference, and the inner circumference rises during processing A manufacturing method has been proposed to prevent the occurrence of such a phenomenon (Patent Document 2).
[0003]
[Patent Document 1] JP-A-6-338125
[Patent Document 2] JP-A-8-210345
[0004]
[Problems to be solved by the invention]
The method of forming grooves for generating dynamic pressure by plastic working such as press working is effective for soft materials such as copper alloys, but is the same on the upper and lower surfaces of the flange part with a hard material such as stainless steel. It is difficult to form the shape stably. In particular, it is difficult to stably form a dynamic pressure generating groove by performing plastic working on a cold drawn material.
That is, as shown in FIG. 8, pressing is performed on the surfaces 3a and 3b of the flange portion 3 of the shaft member 1 including the shaft portion 2 and the flange portion 3 taken out of a cold drawn material (hereinafter, simply referred to as a drawn material). Even when the dynamic pressure generating grooves are formed by performing plastic working such as working, there has been a phenomenon that an appropriate dynamic pressure cannot be obtained in the dynamic pressure bearing formed by the shaft member 1 and the sleeve. The reason is that the residual stress exists in the drawn material, so that even if the press working (plastic working) is performed as designed after the turning (FIG. 9), the flange portion 3 is deformed after forming the dynamic pressure generating groove 4. (Refer to FIG. 10, the deformation in the opposite direction is also possible), and it is considered that the major cause is that the gap 5 between the sleeve 6 and the sleeve 6 is not in an accurate state as designed (see FIG. 11). If residual stress is present, a method using annealing to remove the residual stress is also conceivable. However, according to the annealing, the material becomes too soft, and it is impossible to form a groove for generating dynamic pressure by plastic working such as press working. In addition, machining grooves for generating dynamic pressure on the inner peripheral surface of the sleeve or the thrust plate is complicated and costly, and it is difficult to stably form the same grooves.
[0005]
The present invention has been made in order to address the above-described problem, and has a residual stress inside using a drawn material, and a shaft portion and a flange portion even after plastic working for forming a groove for generating dynamic pressure. It is an object of the present invention to provide a method of manufacturing a dynamic pressure generating groove capable of obtaining a dynamic pressure bearing in which a gap between a shaft member and an inner peripheral surface of a sleeve is integrated as intended.
[0006]
[Means for Solving the Problems]
That is, in order to provide the above object, the invention according to claim 1 provides a shaft member having a shaft portion and a flange portion, and a gap provided between the shaft portion and the flange portion. A sleeve in which the shaft member is fitted, and a dynamic pressure generating groove formed by plastic working on the surface of the flange portion of the dynamic pressure bearing, the method comprising:
When forming the shaft member by turning from a drawn material whose drawing direction is known, first, a shaft member having the same dimensions is taken out, a groove for generating dynamic pressure is formed on the surface of the flange portion, and an outer peripheral end of the flange portion is formed. The distance between the portion and the shaft in the direction perpendicular to the shaft is measured, and the measured value is fed back to take out the shaft member from the drawn material, and the flange is subjected to plastic working.
[0007]
The invention according to claim 2 is characterized in that the flange portion is formed so as to be thinner from the inner diameter portion to the outer diameter portion.
[0008]
The invention according to claim 3 is characterized in that the flange portion is formed so as to increase in thickness from the inner diameter portion to the outer diameter portion.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a drawn member before taking out a shaft member when performing a method of manufacturing a dynamic pressure generating groove (hereinafter, referred to as a dynamic pressure groove) according to the first embodiment of the present invention. In this case, the extracted material W is manufactured by extracting the material through a die (tool) having a tapered hole and reducing the cross-sectional area thereof. In this embodiment, the drawn material W is subjected to turning to take out the T-shaped shaft member 1. The shaft member 1 includes a shaft portion 2 and a flange portion 3, and a herringbone-shaped, V-shaped or partially spiral dynamic pressure groove is formed on both surfaces of the flange portion 3 by press working (plastic working). I do.
[0010]
When forming a dynamic pressure groove in the flange portion 3 of the shaft member 1, first, as shown in FIG. 1, a large number of fine horizontal lines X, X,. . Are inserted, and the shaft portion 2 and the flange portion 3 are turned in parallel along the horizontal lines X, X,... And the vertical lines Y, Y,. The shaft member 1 similar to that shown in FIG. As described later, these X,..., Y,... Are obtained by turning the shaft member 1 once, taking out the press member (plastic working), and then, as shown in FIG. Or the difference d in height between the direction perpendicular to the shaft 2 and the outer peripheral end (difference in axial position between the center side end 3c of the lower side surface 3b of the flange 3 and the outer peripheral end 3d). The measured value is fed back and the value is used as a guide for taking out the correct shaft member 1 by performing the turning process and the press working again.
[0011]
Next, as shown in FIG. 9, the shaft member 1 in which the dynamic pressure grooves 4, 4 are formed on both surfaces of the flange portion 3 by press working is manufactured. In this case, since the shaft member 1 has a residual stress in the drawn material W of the original material, it does not have the dimensions as originally shown in the design drawing in FIG. The flange 3 is inclined at a certain angle (α). Therefore, when the dynamic pressure grooves are formed in advance, if it is known that the flange portion 3 is inclined by α by press working, the inclination angle α is fed back, and as shown in FIG. When the T-shaped shaft member 1 is taken out, if it is turned and pressed in a state inclined in the opposite direction by this angle (α), the processed flange portion 3 becomes as shown in FIG. Thus, the shaft member 1 in an accurate state can be obtained. Therefore, as shown in FIG. 3 (B), the gap 5 between the flange portion 3 having the dynamic pressure groove 4 formed on the surface thereof and the sleeve 6 is an appropriate gap.
[0012]
As described above, the inclination angle α of the flange portion 3 is usually a minute angle, and when an accurate angle cannot be measured, the height difference d (flange) between the direction perpendicular to the shaft 2 and the outer peripheral end portion is determined. The difference in the axial position between the center side end 3c of the lower side surface 3b and the outer peripheral end 3d of the lower side 3b of the portion 3 may be measured, and the numerical value may be fed back.
[0013]
In forming the accurate shaft member 1, it is necessary to clarify the material type (for example, stainless steel, carbon steel, etc.), the drawing direction, the material maker, and the like of the original drawn material W. If such material information is not clear, the state (size and direction) of the internal residual stress after drawing is unknown, and the turning direction during turning is not known. This is because accurate machining cannot be performed unless turning and pressing are repeated.
[0014]
Next, a case where the upper and lower surfaces of the flange portion 3 formed on the shaft member 1 are provided with an inclination will be described. First, a case in which the shaft member 1 is taken out from the drawn material W by turning and formed so as to be thinner from the inner diameter portion to the outer diameter portion (outer peripheral end portion) of the flange portion 3 (second embodiment) Will be described.
When the shaft member 1 is taken out from the drawn material W by turning and formed so as to be thinner from the inner diameter portion to the outer diameter portion (outer peripheral end portion) of the flange portion 3, the upper surface 3 a of the shaft member 1 is removed. As shown in FIG. 4A, when the thickness difference between the thick portion of the lower side surface 3b and the upper and lower outer peripheral ends in the direction perpendicular to the upper and lower shafts 2 is defined as h, h, as shown in FIG. Since residual stress is generated inside the shaft member 1, (h, h) does not become as originally designed, and as shown in FIG. 4B, h ₁ , h ₂ and h ₁ a _{<h 2.} That is, the upper side surface 3a and the lower side surface 3b are not identical because the distribution state of the internal residual stress is different.
[0015]
Next, as shown in FIG. 5 (A), when the shaft member 1 is taken out from the drawn material W by turning, the upper and lower surfaces of the flange portions 3 at the thicker portions and the outer peripheral end portions of the upper side surface 3a and the lower side surface 3b. The height difference in the direction perpendicular to the axis 2 is h ₁ , h ₂ and h ₁ > h ₂ . Then, when the dynamic pressure grooves 4, 4 are formed by press working in this state, as shown in FIG. 5B, the upper surface 3a and the lower surface 3b of the flange portion 3 after the dynamic pressure grooves 4, 4 are formed. The difference between the height of the thick portion and the height of the outer peripheral end in the direction perpendicular to the upper and lower shafts 2 is substantially the same h, h.
[0016]
As described above, and in the press upper and lower surfaces 3a of the machining try to plastic working such as the flange portion 3, h ₁ is the height difference relative to a direction perpendicular to the axis 2 of the end of _3b, h ₂ h if to be a _{1 <h 2} known, in FIG. 1, when taking the shaft member 1 of the T-shaped, by feeding back the difference between the height _(h 1, _{h 2),} shown in FIG. 5 (a) In the opposite direction, turning is performed with a height difference provided in advance. That is, when the shaft member 1 is taken out by turning, if the height of each of the thick portion of the upper surface 3a and the lower side 3b and the peripheral edge portion and h _1, h ₂ and and the h _1> h _2, As shown in FIG. 5B, the height difference between the thick portions of the upper and lower surfaces 3a, 3b of the flange portion 3 after press working and the outer peripheral end thereof in the direction perpendicular to the axis 2 is substantially h. , H can be obtained.
[0017]
Next, in the case where the flange portion 3 formed on the shaft side member 1 is provided with an inclination, the upper and lower surfaces 3a and 3b of the flange portion 3 are thicker from the inner diameter portion to the outer diameter portion (outer peripheral end portion). A case in which it is formed (third embodiment) will be described.
When the shaft member 1 is taken out from the drawn material W by turning and formed so as to be thicker from the inner diameter portion to the outer diameter portion (outer peripheral end portion) of the flange portion 3, the upper surface 3 a of the shaft member 1 is As shown in FIG. 6 (A), when the height of the thick portion of the lower side surface 3b and the height of the outer peripheral end are press-worked as j and j, residual stress is generated inside the shaft member 1. Therefore, in this case as well, (j, j) does not become as originally designed, and as shown in FIG. 6 (B), the height of the flange portion 3 in the direction perpendicular to the upper and lower shafts 2 is slightly increased. The difference is j ₁ , j ₂ and j ₁ <j ₂ . That is, since the distribution of the residual stress is different between the upper side and the lower side, they are not the same.
[0018]
Next, when the shaft member 1 is taken out from the drawn material W by turning, the height of the thick portion of the upper side surface 3a and the lower side surface 3b and the flange portion 3 of the outer peripheral end portion in the direction perpendicular to the upper and lower shafts 2 are formed. The difference between the heights is set to j ₁ , j ₂ and j ₁ > j ₂ . When the dynamic pressure grooves 4 and 4 are formed by press working in this state, as shown in FIG. 7B, the upper surface 3a and the lower surface 3b of the flange portion 3 after the formation of the dynamic pressure grooves 4,4. The height difference between the thick portion and the outer peripheral end portion in the direction perpendicular to the upper and lower shafts 2 is substantially the same j, j.
[0019]
Thus, the upper and lower surfaces 3a of the flange portion 3 in this case try to plastic working even if the difference in height that is j _1, j ₂ knowing for a direction perpendicular to the axis 2 of the end of 3b, FIG. 1 When the T-shaped shaft member 1 is taken out, the height difference (j ₁ , j ₂ ) is fed back to provide a height difference in the opposite direction in advance as shown in FIG. Good. That is, when the shaft member 1 is taken out by turning, if each of the height of the thick portion of the upper surface 3a and the lower side 3b and the outer peripheral end portion Te j _1, j ₂ and the j _1> j _2, As shown in FIG. 7 (B), the height difference between the thick portions of the upper and lower surfaces 3a, 3b of the flange portion 3 after press working and the outer peripheral end thereof in the direction perpendicular to the axis 2 is substantially j. , J can be obtained.
[0020]
In the embodiment of the present invention, the case where the shaft member 1 has a T-shape has been described. However, it is needless to say that a shaft member having the flange portion 3 formed around the shaft portion 2 may be used. Further, the present invention can also be applied to a case where only the upper surface 3a or only the lower surface 3b of the flange portion 3 is provided with an inclination or the groove 4 for generating dynamic pressure is formed. Further, in the T-shaped shaft member 1, as shown in the figure, a concave portion 3c is formed at the center of the T-shaped apex. good.
[0021]
Table 1 shows that in the method of manufacturing a groove for generating dynamic pressure of the present invention, in particular, in the third embodiment, a shaft portion 2 and a flange portion 3 are actually formed by turning a drawn material W (stainless steel). the shaft member 1 is taken out, the difference between the respective heights of the thick portion and the outer peripheral edge portion of the side surface 3a and the lower surface 3b on the shaft member 1, as shown in FIG. 6 (a), j ₁ before pressing, j ₂ values were produced 3 times respectively, a table showing the results of measuring the value after pressing.
[Table 1]

As shown in Table 1, if the shaft member 1 taken out from the drawn material by the turning process is fed back to form the flange portion 3 in consideration of the influence of the residual stress, the shaft portion 2 and the flange portion 3 are formed. It has been found that the shaft member 1 can have a substantially accurate squareness.
[0022]
【The invention's effect】
As described in detail above, according to the method for producing a groove for generating dynamic pressure of the present invention, when a drawn material such as stainless steel or carbon steel is used, residual stress is present inside such as pressing. An accurate dynamic pressure bearing can be obtained in which the clearance between the shaft member and the inner peripheral surface of the sleeve, in which the shaft and the flange portion are integrated after processing the dynamic pressure generating groove by plastic working, is intended. Further, according to the manufacturing method of the present invention, complicated processing of a dynamic pressure generating groove in a sleeve, a thrust plate or the like becomes unnecessary. Furthermore, since the same dynamic pressure generating groove can be simultaneously formed on both upper and lower surfaces of the flange portion provided on the shaft, the number of steps can be reduced. Also, when machining grooves for generating dynamic pressure on the upper and lower surfaces of the flange provided on the shaft, the same shape of grooves for generating dynamic pressure can be obtained stably, so the accuracy after assembly is improved and defective products are generated. Therefore, the manufacturing cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a view showing a cold-drawn material before a shaft member is taken out when a method of manufacturing a groove for generating dynamic pressure according to the present invention is carried out.
FIG. 2 is a view showing a shaft member which is turned in a state where the shaft member is inclined by an angle of strain generated in the opposite direction in consideration of a result of press working in advance when removing a T-shaped shaft member.
FIG. 3 (A) is a view showing a shaft member in a state where a shaft member which has been turned in a state where the shaft member is inclined by an angle of strain generated in the opposite direction in consideration of a result of pre-pressing is pressed. FIG. 3B is a cross-sectional view of a state in which the shaft member is fitted in a sleeve.
FIG. 4 shows a case where the shaft member taken out from the drawn material is formed so that the thickness is reduced from the inner diameter portion to the outer diameter portion (outer peripheral end portion) of the flange portion, and FIG. FIG. 4B is a partial cross-sectional view showing a state before, and FIG. 4B is a partial cross-sectional view showing a state after additional pass processing.
FIG. 5 shows a case where the shaft member taken out of the drawn material is formed so that the thickness is reduced from the inner diameter portion to the outer diameter portion (outer peripheral end portion) of the flange portion, and FIG. FIG. 5B is a partial cross-sectional view illustrating a state before the pressing, and FIG. 5B is a partial cross-sectional view illustrating a state after the pressing.
FIG. 6 shows a case where the shaft member taken out of the drawn material is formed so that the thickness increases from the inner diameter portion to the outer diameter portion (outer peripheral end portion) of the flange portion, and FIG. FIG. 6B is a partial cross-sectional view showing a state before, and FIG. 6B is a partial cross-sectional view showing a state after additional pass processing.
FIG. 7 shows a case where the shaft member taken out from the drawn material is formed so that the thickness increases from the inner diameter portion to the outer diameter portion (outer peripheral end portion) of the flange portion, and FIG. FIG. 7B is a partial cross-sectional view showing a state before, and FIG. 7B is a partial cross-sectional view showing a state after press working.
FIG. 8 is a diagram showing a T-shaped shaft member including a shaft portion and a flange portion taken out from a cold drawn material by turning.
FIG. 9 is a view showing a state in which press working is performed to form a dynamic pressure generating groove in a flange portion of a shaft member taken out from a cold drawn material by turning.
FIG. 10 is a view showing a state in which pressing is performed to form a dynamic pressure generating groove in a flange portion of a shaft member taken out from a cold drawn material by turning.
FIG. 11 is a sectional view of a dynamic pressure bearing in a state where a dynamic pressure generating groove is formed in a flange portion of a shaft member taken out from a cold drawn material by turning, and the shaft member is fitted into a sleeve. It is.
[Explanation of symbols]
1 Shaft member 2 Shaft 3 Flange 4 Groove for generating dynamic pressure

Claims (3)

Surface of the flange portion of a hydrodynamic bearing composed of a shaft member having a shaft portion and a flange portion, and a sleeve in which a gap is provided between the shaft portion and the flange portion and the shaft member is fitted. In the method for producing a dynamic pressure generating groove to form a dynamic pressure generating groove by plastic working,
When forming the shaft member by turning from a drawn material of which the drawing direction is known, first, the shaft member according to dimensions is taken out, a groove for generating dynamic pressure is formed on the surface of the flange portion, and the outer peripheral end of the flange portion is formed. Measuring the distance of the part in the direction perpendicular to the shaft part and then feeding back the measured value to take out the shaft member from the drawn material and subjecting the flange part to plastic working to produce a groove for generating dynamic pressure Method. The method for manufacturing a groove for generating dynamic pressure according to claim 1, wherein the flange portion is formed so as to be thinner from an inner diameter portion to an outer diameter portion. The method for manufacturing a groove for generating dynamic pressure according to claim 1, wherein the flange portion is formed so as to increase in thickness from an inner diameter portion to an outer diameter portion.

Images