JP5982610B2 - Plastic bearing - Google Patents

Description

  The present invention relates to a plastic bearing that rotatably holds a rotating shaft provided in an air conditioner device, an OA device, or the like.

  Conventionally, as this type of plastic bearing, the outer shape is formed in a cylindrical shape, and a plurality of articulated rings projecting at a constant height in the shaft hole are provided at predetermined intervals in the length direction of the shaft hole formed in the center portion thereof. There has been proposed a structure in which lubricating oil is stored in recessed portions formed between the connecting rings (see, for example, FIG. 1 of Patent Document 1). In the plastic bearing described in Patent Document 1, since the lubricating oil is accumulated in the recesses formed between the connecting rings, the friction coefficient is small, and the power consumption of the motor that rotationally drives the rotating shaft can be suppressed. Oil leakage is less likely to occur and the product life can be extended.

  However, in order to manufacture a plastic bearing having such a configuration by an injection molding method, a pin-shaped shaft hole forming mold having a concave portion for forming a connecting ring and a convex portion for forming a concave portion However, it is difficult to take out the plastic bearing formed around the shaft hole forming mold having irregularities, so that it is extremely difficult to efficiently manufacture non-defective products. Or practically impossible.

  In order to solve such a problem, shaft holes that have the same inner diameter at both ends in the axial direction and are inflated in the middle in the axial direction by using sink marks due to curing shrinkage of the molten resin generated during injection molding. Conventionally, a resin bearing in which is formed has been proposed (see, for example, FIG. 1 of Patent Document 2). Since the resin bearing described in Patent Document 2 can be manufactured without using a shaft hole forming mold having irregularities, a non-defective product can be manufactured efficiently. Further, FIG. 1 of Patent Document 2 also describes a rib-like thick portion projecting radially or blade-like from the central portion of the outer surface of a cylindrical molded bearing.

JP 2008-157290 A Japanese Unexamined Patent Publication No. 07-121894

  By the way, a plastic bearing that rotatably holds a rotating shaft provided in an air conditioner device, an OA device, or the like is attached to a housing of the air conditioner device, the OA device, or the like via a rubber bush. Therefore, it is desirable to form rib-shaped detent projections on the outer surface of the plastic bearing in order to prevent slipping between the rubber bush and the plastic bearing and to set the plastic bearing at a predetermined position of the housing. As described above, Patent Document 2 describes a resin bearing in which a rib-like thick portion is radially or blade-like projected on the outer peripheral portion, so that when this resin bearing is used, The rib-like thick portion can be made to bite into the rubber bush, and slipping between the rubber bush and the plastic bearing can be prevented, and the plastic bearing can be reliably installed at a predetermined position of the housing.

  However, the plastic bearing described in Patent Document 2 uses a sink caused by the cure shrinkage of the molten resin to form a shaft hole that swells in a middle shape in the axial direction, and is caused by the cure shrinkage of the molten resin. The size of the sink marks changes depending on the thickness difference of each part of the resin bearing. Therefore, when the rib-shaped thick part is projected radially or blade-like from the center of the outer surface of the cylindrical molded bearing, a part where the rib-shaped thick part is formed and a part where this is not formed In this case, a difference occurs in the amount of sink marks of the resin, and the roundness of the shaft hole is deteriorated. Needless to say, if the roundness of the shaft hole deteriorates, the slidability of the rotating shaft deteriorates, causing vibrations due to the runout of the rotating shaft, or the lubricant stored in the Tyco-shaped recesses. The problem of flowing out and loss of lubricity within a short period is likely to occur.

  The present invention has been made to solve such problems of the prior art, and an object thereof is to suppress the vibration of the rotating shaft and to smoothly rotate the rotating shaft over a long period of time. To provide plastic bearings.

  In order to solve such a technical problem, the present invention protrudes radially from a cylindrical main body portion having an axial hole for rotatably holding a rotating shaft at a central portion, and an outer surface of the main body portion. A plurality of first ribs, and a second rib connecting the plurality of first ribs and projecting in the circumferential direction of the main body, and the shaft hole is formed at an intermediate portion in the length direction of the main body. The main body portion has a drum-shaped concave portion that has a maximum diameter in the central portion in the length direction and decreases in diameter as it reaches both end portions in the length direction of the main body portion. The shape of the tip is formed in an arc shape in which the height dimension is the largest in the central part in the length direction of the main body part, and the height dimension decreases as it reaches both ends in the length direction of the main body part, The second rib is formed at a central portion in the length direction of the main body, Dimensioned, the is the same as the height of the first rib in the central portion in the length direction of the main body portion, characterized in that.

  The drum-shaped concave portion of the shaft hole is formed by utilizing sink marks due to curing shrinkage of the molten resin generated when the plastic bearing is injection molded. As described above, the amount of sink marks of the molded product changes depending on the difference in thickness of each part, but the first part in the center part in the length direction of the main body part is arranged at the center part in the length direction of the main body part. If the second rib having the same dimension as the height of the rib is formed in a ring shape, the difference in thickness in the circumferential direction of the central portion of the main body can be reduced. Therefore, the amount of sink marks of the molded product in the circumferential direction of the main body can be made uniform, and a shaft hole with a high roundness can be formed in the plastic bearing. Thus, if a shaft hole with high roundness is formed in a plastic bearing, the slidability of a rotating shaft can be improved and the vibration of the rotating shaft accompanying rotation can be suppressed. In addition, since the lubricating oil stored in the drum-shaped recess is less likely to flow out, high lubricity can be maintained over a long period of time.

  According to the present invention, in the plastic bearing having the above-described configuration, the thickness of the main body at both ends of the drum-shaped recess is t, the thickness of the first rib at the connection with the main body is db, and the second rib. When the thickness of each is da, the dimensions of each part satisfy the following first and second formulas.

da ≧ 2 × t / 3 (1st formula)
2 × t / 3 ≧ db ≧ t / 2 (2nd formula)
According to the experiment, by setting the dimensions of each part of the molded product so as to satisfy the first and second formulas, a drum shape that can store a predetermined amount of lubricating oil in the middle part of the axial direction of the shaft hole It has been found that a recess can be formed and the roundness of both end sides of the shaft hole can be increased. Therefore, the vibration of the rotating shaft can be suppressed, and the outflow of the lubricating oil stored in the drum-shaped recess can be prevented, and high lubricity can be maintained over a long period of time.

  According to the present invention, in the plastic bearing having the above-described configuration, the main body, the first rib, and the second rib are integrally formed by injection molding.

  In the case of injection molding of plastic bearings, if the dimensions of each part of the molded product are set so as to satisfy the above-mentioned first and second formulas, a drum-shaped recess may be formed in the middle portion in the length direction of the shaft hole. it can. Therefore, it is possible to use a mold having no irregularities as a mold for forming the shaft hole, and it is not necessary to forcibly pull out the molded product from the mold, so that a non-defective product can be manufactured with high efficiency.

  A plastic bearing according to the present invention includes a cylindrical main body portion having a shaft hole for rotatably holding a rotating shaft at a central portion, a plurality of first ribs projecting radially from an outer surface of the main body portion, and a main body Since the plurality of first ribs are connected at the central portion in the length direction of the portion and the second rib protruding in the circumferential direction of the main body portion is provided, a drum-shaped concave portion is provided in the middle portion in the length direction, And a shaft hole with high roundness can be formed. Therefore, the slidability of the rotating shaft can be improved, vibration of the rotating shaft accompanying rotation can be suppressed, and the lubricating oil stored in the drum-shaped recess can be made difficult to flow out to the outside, which is high. Lubricity can be maintained over a long period of time. And since high lubricity can be maintained over a long period of time, the torque loss of the rotating shaft and the generation of frictional heat accompanying the rotation of the rotating shaft can be suppressed, and the generation of noise due to running out of oil can be prevented.

It is a perspective view of the plastic bearing which concerns on embodiment. It is a central part cross-sectional view of the plastic bearing which concerns on embodiment. It is a central part longitudinal cross-sectional view of the plastic bearing which concerns on embodiment. It is sectional drawing of the use condition of the plastic bearing which concerns on embodiment. It is a table | surface figure which shows the structure and performance of the plastic bearing which concern on an Example. It is a table | surface which shows the structure and performance of the plastic bearing which concerns on a comparative example.

  Hereinafter, embodiments of a plastic bearing according to the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 to 4, the plastic bearing 1 according to the embodiment includes a cylindrical main body 3 having a shaft hole 2 in the center and a plurality of radial protrusions formed from the outer surface of the main body 3. It has the 1st rib 4 and the 2nd rib 5 formed in the circumferential direction of the outer surface of the main-body part 3. As shown in FIG. The plastic bearing of this example is made of a resin material and is integrally formed by injection molding.

  As shown in FIG. 3, the shaft hole 2 has a maximum diameter at the central portion in the length direction of the main body portion 3 except for both end portions in the length direction of the main body portion 3, and the length of the main body portion 3. It has a drum-like concave portion 6 whose diameter decreases as it reaches both ends of the direction. The surface on which the drum-shaped recess 6 is formed is formed in a spherical shape. Further, chamfers 7 for facilitating the mounting of the rotating shaft S (see FIG. 4) are provided at both ends of the main body 3 in the length direction.

  As shown in FIG. 2, the cross-sectional shape of the 1st rib 4 is formed in the substantially sector shape where the width | variety at the base, ie, the side which contact | connects the main-body part 3, is small, and a width | variety becomes large toward the front end side. Further, as shown in FIG. 3, the side surface shape of the first rib 4 has the largest height dimension at the center portion in the length direction of the main body portion 3, and increases as it reaches both end portions in the length direction of the main body portion 3. It is formed in an arc shape with a small dimension. Both ends of the first rib 4 reach both ends in the length direction of the main body 3.

  The second rib 5 is formed at the center in the length direction of the main body 3, and is formed to project in the circumferential direction of the main body 3 by connecting each of the plurality of first ribs 4. The height dimension of the second rib 5 is the same as the height dimension of the first rib 4 at the central portion in the length direction of the main body 3, and the leading end of the first rib 4 and the leading end of the second rib 5 Are connected smoothly.

  As shown in FIG. 4, the plastic bearing 1 according to the present embodiment is set to a housing C such as an air conditioner device or an OA device via a rubber bush B, and rotatably holds a rotating shaft S such as a motor shaft. If it does in this way, the 1st rib 4 and the 2nd rib 5 which were formed in the plastic bearing 1 will bite into the rubber bush B, and the sliding between the plastic bearing 1 and the rubber bush B will be carried out so that it may become clear from the same figure. Since it can prevent, the plastic bearing 1 can be reliably installed in the predetermined position of the housing C.

  FIG. 5 shows the configuration and performance of the plastic bearing according to the example, and FIG. 6 shows the configuration and performance of the plastic bearing according to the comparative example. 5 and 6 indicate the thickness of the main body 3, the thickness of the second rib 5, the height of the second rib 5, and the first rib 4 respectively. And the maximum height of the first rib 4 (see FIGS. 2 and 3).

  As shown in FIG. 5, the plastic bearings according to Examples 1 to 6 are made of polyethylene resin (PE) to which 5% hydrocarbon mineral oil is added.

  The plastic bearings according to Examples 7 to 12 are made of polyphenylene sulfide resin (PPS) to which 3% silicone oil is added.

  The plastic bearings according to Examples 13 to 18 are made of polyoxymethylene resin (POM) to which 3% mineral oil is added.

  The plastic bearings according to Examples 19 to 24 are made of polypropylene resin (PP) to which 5% hydrocarbon mineral oil is added.

  As shown in FIG. 6, the plastic bearing according to Comparative Example 1 is made of polypropylene resin (PP) to which 5% hydrocarbon mineral oil is added.

  The plastic bearings according to Comparative Examples 2 to 11 are made of polyethylene resin (PE) to which 5% hydrocarbon mineral oil is added.

  The plastic bearings according to Comparative Examples 12 to 21 are made from polyphenylene sulfide resin (PPS) to which 3% silicone oil is added.

  The plastic bearings according to Comparative Examples 22 to 31 are made of polyoxymethylene resin (POM) to which 3% mineral oil is added.

  The plastic bearings according to Comparative Examples 32-41 are made of polypropylene resin (PP) to which 5% hydrocarbon mineral oil is added.

  The height Ha of the second rib 5 and the maximum height Hb of the first rib 4 were set to 2 mm for all of Examples 1 to 24 and Comparative Examples 1 to 41. And about Examples 1-24, the thickness t of the main-body part 3, the thickness da of the 2nd rib 5, and the thickness of the 1st rib 4 so that both the following 1st formula and 2nd formula may be satisfy | filled. db was set. On the other hand, for Comparative Examples 1 to 41, the thickness t of the main body 3, the thickness da of the second rib 5, the first thickness so as not to satisfy any one of the following first and second formulas The thickness db of 1 rib 4 was set.

da ≧ 2 × t / 3 (1st formula)
2 × t / 3 ≧ db ≧ t / 2 (2nd formula)
As is clear from the comparison between FIG. 5 and FIG. 6, the plastic bearing according to the example has a roundness of the shaft hole 2 of 0.008 mm to 0.03 mm, whereas the plastic bearing according to the comparative example is The roundness is 0.003 mm to 0.08 mm. From this, it can be seen that the plastic bearing according to the example has a smaller roundness of the shaft hole 2 and is more stable than the plastic bearing according to the comparative example.

  Further, as apparent from the comparison between FIG. 5 and FIG. 6, the plastic bearing according to the example has a depth of the drum-shaped recess 6 of 0.02 mm to 0.07 mm and a width of the drum-shaped recess 6 of 3.5 mm. On the other hand, in the plastic bearing according to the comparative example, the depth of the drum-shaped recess 6 is 0.003 mm to 0.09 mm, and the width of the drum-shaped recess 6 is 0.04 mm to 7 mm. From this, the plastic bearing according to the example is formed in a size that allows the drum-shaped recess 6 to be stable and store a sufficient amount of lubricating oil as compared with the plastic bearing according to the comparative example. I understand that.

  The plastic bearing according to the example and the plastic bearing according to the comparative example were each used as a bearing of a motor shaft, and the motor was continuously operated to test the durability of each plastic bearing. As a result, the plastic bearing according to the example had the required lubricity even after a predetermined durability test, and no particular abnormality occurred as indicated by a circle in FIG. On the other hand, the plastic bearing according to the comparative example has an increase in the torque loss of the motor shaft and an abnormal temperature rise of the plastic bearing due to frictional heat as indicated by a cross in FIG. An abnormality such as friction noise occurred.

  In the embodiment, the plastic bearing 1 is injection-molded using a resin material in which oil is kneaded. However, instead of such a configuration, the plastic bearing 1 is injection-molded using a resin material in which oil is not kneaded. After that, it is possible to take a method of dipping the produced plastic bearing 1 in oil.

  Further, the plastic bearing according to the present invention is not limited to the one manufactured using the resin material illustrated in FIG. 5, and is manufactured using another resin material as long as it has a predetermined hardness. You can also Other resin materials include acrylonitrile-butadiene-styrene, liquid crystal polymer, polyamide, polyamideimide, amorphous polyarylate, polybutylene terephthalate, polycarbonate, polyetheretherketone, polyetherimide, polyethersulfone, polyethersulfone, Examples thereof include polyether terephthalate, polymethyl methacrylate, polymethyl pentene, polyphthalamide, polyphenylene ether, polystyrene, polysulfone, and polyvinyl chloride.

  Furthermore, the lubricating oil added to the plastic bearing according to the present invention is not limited to that illustrated in FIG. 5, and other lubricating oils can be used. Examples of other lubricating oils include olefin oil, ester oil, and machine oil.

  INDUSTRIAL APPLICABILITY The present invention can be used for a bearing that holds a rotating shaft of a small motor provided in an air conditioner device, an OA device, or the like.

DESCRIPTION OF SYMBOLS 1 Plastic bearing 2 Shaft hole 3 Main-body part 4 1st rib 5 2nd rib 6 Taiko-shaped recessed part 7 Chamfering B Rubber bush C Housing S Rotating shaft

Claims (3)

A cylindrical main body having a shaft hole for rotatably holding the rotary shaft at the center, a plurality of first ribs projecting radially from the outer surface of the main body, and the plurality of first ribs are connected. And a second rib protruding in the circumferential direction of the main body,
The shaft hole has a maximum diameter in the middle portion in the length direction of the main body portion, the diameter in the center portion in the length direction of the main body portion, and the diameter increases toward both end portions in the length direction of the main body portion. Having a smaller drum-shaped recess,
The shape of the tip of the first rib has the largest height at the center in the length direction of the main body, and the height decreases as it reaches both ends of the length of the main body. Formed in an arc shape,
The second rib is formed at a central portion in the length direction of the main body portion, and a height dimension thereof is the same as a height dimension of the first rib at a central portion in the length direction of the main body portion.
Plastic bearing characterized by that. Dimension of each part, where t is the thickness of the main body at both ends of the drum-shaped recess, db is the thickness of the first rib at the connection with the main body, and da is the thickness of the second rib. The plastic bearing according to claim 1, satisfying the following first and second formulas:
da ≧ 2 × t / 3 (1st formula)
2 × t / 3 ≧ db ≧ t / 2 (2nd formula)   The plastic bearing according to any one of claims 1 and 2, wherein the main body, the first rib, and the second rib are integrally formed by injection molding.