JP3757310B2 - Resin sleeve and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin sleeve that supports, for example, a rotating shaft of a fan motor and a method for manufacturing the same.
[0002]
[Prior art]
As a bearing that rotatably supports a shaft with a relatively small diameter, such as a rotating shaft of a fan motor, for example, a resin sleeve formed by engraving a radial dynamic pressure groove on the inner peripheral surface is often used. Has been. This type of resin sleeve is a cylindrical body as a whole, and each resin sleeve 41 is schematically shown in FIG. 4 as a sectional view in use when two resin sleeves 41 are used in series. The outer peripheral surface is fixed in a state of being fitted into a hole 42a formed in the housing 42 (a stator in the case of a fan motor). At this time, an elastic body 43 such as rubber may be interposed between the outer periphery of each resin sleeve 41 and the hole 42a of the housing 42 as shown in the figure.
[0003]
As a method of fixing the resin sleeve 41 to the housing 42 or the elastic body 43, a method of bonding the resin sleeve 41 to the hole 42a or the elastic body 43 of the housing 42 using an adhesive, and a method of fixing the resin sleeve 41 to the housing. One of the methods of fixing by pressing into the elastic body 43 inside the hole 42a of 42 is employ | adopted. The rotating shaft 44 (rotor shaft in the case of a fan motor) is inserted into the inner surface of the sleeve 41 in which a dynamic pressure groove is formed, and is rotatably supported.
[0004]
The resin sleeve 41 as described above is conventionally molded by an injection molding method based on a mold configuration whose cross-sectional view is illustrated in FIG. That is, a cylindrical cavity is formed between molds 51 and 52 that can be moved toward and away from each other, and a core mold 53 is inserted into the center of the cavity to thereby form the molds 51 and 52 and the core mold. A cylindrical cavity 54 is formed by 53. A method is generally employed in which a gate 55 is provided on one end face side of the cavity 54, and molten resin is injected and injected into the cavity 54 through the gate 55.
[0005]
[Problems to be solved by the invention]
By the way, in the conventional resin sleeve 41 as described above, when the method using an adhesive is employed as a fixing method for the hole 42a of the housing 42 or the elastic body 43 disposed inside the hole 42a, the assembly man-hour is required. In addition, when adopting a method of fixing by press-fitting, it is necessary to strictly control both the outer diameter of the resin sleeve 41 and the inner diameter of the hole 42a. This is the cause of the increase.
[0006]
The present invention has been made in view of such circumstances, and without using an adhesive, and without strictly controlling the dimensions of the outer diameter surface of the sleeve and the inner diameter surface of the housing. It is an object of the present invention to provide a resin sleeve and a method for manufacturing the resin sleeve that can be firmly fixed and can be reduced in cost.
[0007]
In order to achieve the above object, the resin sleeve of the present invention is a resin sleeve used in a state where the outer periphery is fitted and fixed in a hole formed in the housing.
A plurality of convex portions are formed on the outer peripheral surface with a certain interval in the circumferential direction, and each convex portion has a length in the sleeve axial direction shorter than the axial length of the sleeve itself . The outer diameter dimension of the portion excluding the convex portion is fitted to the inner diameter surface of the hole formed in the housing via a cylindrical elastic body, and is smaller than the inner diameter dimension of the cylindrical elastic body, and The dimension from the center of the sleeve to the tip of each convex part is characterized by being larger than the inner diameter dimension of the cylindrical elastic body.
[0008]
The resin sleeve manufacturing method of the present invention is a resin sleeve used in a state where the outer periphery is fitted and fixed in a hole formed in the housing, and the outer periphery is a fitting surface with respect to the hole of the housing. A method of manufacturing a resin sleeve having a plurality of convex portions formed on a surface with a certain interval in the circumferential direction by using an injection molding method, and two molds that are relatively close to and away from each other A cylindrical cavity is formed using an injection mold that is removably inserted into a cavity formed by the two molds, and an outer periphery of the cylindrical cavity. By injecting and injecting molten resin into the cavity from a plurality of gates provided at regular intervals in the circumferential direction on the surface, the gate protrudes from the outer peripheral surface of the molded product and the projections are formed. To form It characterized me.
[0009]
In the present invention, the resin sleeve is not fixed to the housing hole by surface contact, but is attached to the outer peripheral surface of the resin sleeve, which is the fitting surface with respect to the housing hole, from the axial dimension of the sleeve. at regular intervals a plurality of convex portions in the circumferential direction also have a shorter same dimension set Keru other hand, adopting the structure of fitting through a cylindrical elastic body this sleeve against the inner diameter surface of the housing of the hole Thus, each convex portion of the resin sleeve is bitten into a cylindrical elastic body and fixed to each other, thereby achieving the intended purpose.
[0010]
That is, a plurality of convex portions having the same dimension shorter than the axial dimension of the sleeve are formed at a certain interval in the circumferential direction on the outer peripheral surface of the resin sleeve, and the sleeve is formed into a cylindrical elastic body. By fixing in the hole of the housing in a state of interposing the resin, each convex part bites into the elastic body, so that the resin sleeve is substantially press-fitted into the hole of the housing, and the adhesive It can be securely fixed to the housing without using. Moreover, the outer diameter dimension of the resin sleeve excluding the formation of each convex part and the inner diameter dimension of the hole in the housing are significantly less dimensional management than when using a conventional press-fitting method. can do.
[0011]
Further, the resin sleeve manufacturing method of the present invention is a resin sleeve in which a plurality of convex portions are formed at regular intervals in the circumferential direction on the outer peripheral surface, like the resin sleeve of the invention according to claim 1 described above . the formation of each of the convex part which easily realized by utilizing a gate mark at the time of injection molding. That is, a resin sleeve is formed by injecting and solidifying molten resin by providing a gate at a certain interval in the circumferential direction on the outer periphery of a cylindrical cavity formed by an injection mold, and the outer periphery thereof. By using the gate traces remaining on the surface as they are to form the convex portions, the resin of the invention according to claim 1 can be obtained without complicating the mold configuration and the manufacturing process, and thus at a low cost. A sleeve can be obtained.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an external view of an embodiment of a resin sleeve according to the present invention.
The resin sleeve 1 of this embodiment has a cylindrical shape as a whole as in the prior art, and a dynamic pressure groove 11a is formed on the inner peripheral surface 11 thereof, and the outer peripheral surface 12 has an axial center. A plurality of convex portions 12a are formed at regular intervals in the circumferential direction along the circumference of the portion.
[0013]
When the above-described resin sleeve 1 is used in the same manner as shown in FIG. 4, the outer surface of the cylindrical elastic body 43 disposed in the hole 42a of the housing 42 is outside the portion excluding the convex portions 12a. The diameter dimension is set to be slightly smaller, and the dimension from the sleeve center to the tip of each convex portion 12a is set to be slightly larger than the radius of the inner surface of the elastic body 43. Then, when fitting and fixing to the inner surface of the elastic body 43, each convex portion 12 a bites into the elastic body 43 so that the resin sleeve 1 is substantially press-fitted into the elastic body 43. Without using an adhesive, the elastic body 43 is firmly fixed.
[0014]
The resin sleeve 1 having such a shape can be molded by an injection molding method based on the following mold configuration. FIG. 2 shows the mold configuration in a longitudinal sectional view. FIG. 3 is a cross-sectional view taken along the line AA in FIG.
[0015]
In this example, a cylindrical cavity is formed inside the upper mold 21 and the lower mold 22 that can be relatively approached and separated from each other, and a core mold 23 is removably provided in the cavity. These upper mold 21, lower mold 22 and core mold 23 form a cylindrical cavity 24. A dynamic pressure groove mold 23 a is formed on the outer peripheral surface of the core mold 23.
[0016]
The parting line P between the upper mold 21 and the lower mold 22 is provided at the center in the vertical direction of the cavity 24, and along the parting line P, a constant interval is provided in the circumferential direction on the outer periphery of the cavity 24. A plurality of gates 25 are provided. Each gate 25 includes a small cylindrical portion 25a in contact with the cavity 24, and has a shape including a narrowed portion 25b narrowed down following the small cylindrical portion 25a. As shown in FIG. 3, each gate 25 communicates with the sprue 27 via a runner 26 including a circumferential portion that goes around the cavity 24 and a radial portion that leads from the circumferential portion to each gate 25. Yes.
[0017]
With the above mold configuration, the molten resin is injected and injected into the cavity 24 and solidified, and then released from the molded product. After each gate 25 is cut at the narrowed portion 25b, the outer peripheral surface of the molded product is The small cylindrical portion 25a protrudes corresponding to the position of each gate 25, and by leaving these as they are, the convex portion 12a is formed with a certain circumferential interval on the outer peripheral surface 12. FIG. The resin sleeve 1 shown in FIG.
[0018]
In the above embodiment, an example in which each convex portion 12a is formed along the circumference of the axially central portion of the outer peripheral surface 12 is shown, but the present invention is not limited to this, and each convex portion 12a is formed. The formation position of the part 12a can be an arbitrary position in the axial direction.
[0019]
Further, in the present invention, as shown in FIG. 4, in addition to the resin sleeves that are used by arranging two in series in the housing 42, two sets of motions are provided at predetermined intervals in the axial direction on the inner peripheral surface. Of course, the present invention is equally applicable to a structure in which a pressure groove is formed and the rotating shaft is supported by a single resin sleeve.
[0020]
【The invention's effect】
As described above, according to the resin sleeve of the present invention, a plurality of convex portions are formed on the outer peripheral surface at regular intervals in the circumferential direction, and this is formed in a state where the cylindrical elastic body is interposed. Since it is configured to be fixed to the hole, when the resin sleeve is incorporated into the elastic body, each convex portion bites into the housing-side elastic body, thereby pressing into the housing-side elastic body. It can be fixed with the same or higher firmness, can reduce the number of assembly steps compared to fixing with an adhesive, and compared to fixing by press-fitting to the housing, The dimensional control of the housing and the resin sleeve can be greatly relaxed, and the cost can be reduced.
[0021]
In addition, according to the method for manufacturing a resin sleeve of the present invention, a plurality of gates are formed on the outer periphery of the cavity at a constant interval in the circumferential direction, and the above-described convex portions are formed by leaving the gate marks. The resin sleeve of the present invention can be manufactured under a simple mold configuration and a simple manufacturing process, and the above-described effect of the resin sleeve according to the present invention can be achieved without increasing the manufacturing cost. Can do.
[Brief description of the drawings]
FIG. 1 is an external view of a resin sleeve to which the present invention is applied.
2 is a longitudinal sectional view showing an example of a mold configuration for producing the resin sleeve of FIG. 1; FIG.
3 is a cross-sectional view taken along a line AA in FIG.
FIG. 4 is a cross-sectional view showing an example of a usage state of a conventional resin sleeve.
5 is a longitudinal sectional view showing a configuration example of an injection mold for molding the resin sleeve of FIG. 4; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Resin sleeve 12 Outer peripheral surface 12a Convex part 21 Upper die 22 Lower die 23 Core die 24 Cavity 25 Gate 25a Small cylindrical part 25b Constriction part 26 Runner 27 Sprue

Claims (2)

In the resin sleeve used in a state where the outer periphery is fitted and fixed in the hole formed in the housing,
A plurality of convex portions are formed on the outer peripheral surface with a certain interval in the circumferential direction, and each convex portion has a length in the sleeve axial direction shorter than the axial length of the sleeve itself . The outer diameter dimension of the portion excluding the convex portion is fitted to the inner diameter surface of the hole formed in the housing via a cylindrical elastic body, and is smaller than the inner diameter dimension of the cylindrical elastic body, and A resin sleeve characterized in that a dimension from the center of the sleeve to the tip of each convex portion is larger than an inner diameter dimension of the cylindrical elastic body. A resin sleeve that is used in a state where the outer periphery is fitted and fixed in a hole formed in the housing. A method of manufacturing a resin sleeve formed with a convex portion using an injection molding method,
Cylindrical cavity using an injection mold comprising two molds that are relatively close to and away from each other and a core mold that is removably inserted into a cavity formed by the two molds. And forming a solid resin by injecting molten resin into the cavity from a plurality of gates provided at regular intervals in the circumferential direction on the outer peripheral surface of the cylindrical cavity. A method for producing a resin sleeve, wherein the convex portion is formed by projecting from an outer peripheral surface of a molded product.

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