JP5586908B2 - Plain bearing - Google Patents

Description

  The present invention relates to a slide bearing for supporting a shaft member, and particularly to a slide bearing for supporting a shaft member having a shaft diameter (diameter) of 6 to 20 mm.

  As a slide bearing, a so-called electroformed bearing having a bearing surface formed in an electroformed portion has been proposed (for example, Patent Document 1). The electroformed bearing includes (1) an electroformed part forming step of depositing and forming an electroformed part on the outer peripheral surface of the master, and (2) a resin part that holds the outer peripheral surface of the electroformed part using the electroformed part and the master as insert parts. The resin part is molded by injection molding and (3) a separation process of pulling out the master from the inner periphery of the slide bearing.

  Electroformed bearings have high dimensional accuracy (for example, cylindricity) and surface accuracy (for example, surface roughness) on the outer peripheral surface of the master because the inner peripheral surface of the electroformed part that becomes the bearing surface follows the accuracy of the outer peripheral surface of the master. An accurate bearing surface can be obtained by processing with high accuracy. For this reason, the electroformed bearing is applied to an application for supporting a small-diameter shaft (shaft diameter of 6 mm or less) that is expected to rotate at a high speed, such as a small fan motor or an HDD disk drive device (for example, Patent Documents). 1).

  On the other hand, as a bearing applied to support a shaft member (shaft diameter of about 6 to 20 mm) larger than the above-described small-diameter shaft, for example, a rotating shaft such as a roller of office equipment, a rolling bearing is used. Is mainly used (for example, Patent Document 2).

JP 2007-239795 A JP 2008-256085 A

  The inventor of the present invention tried to apply an electroformed bearing, which has been conventionally applied exclusively for supporting a small-diameter shaft, as an application for supporting a relatively large-diameter shaft member. By applying the electroformed bearing to such a use, the manufacturing cost can be greatly reduced as compared with the rolling bearing.

  However, in attempting to increase the diameter of the electroformed bearing, the following problems that did not occur in the case of supporting a small diameter shaft occurred. That is, when the shaft diameter is increased, the resin portion that holds the electroformed portion is also increased in diameter, so that the amount of reduction in the inner diameter due to molding shrinkage of the resin portion increases, and the pressure applied to the electroformed portion increases. If the electroformed part is deformed by this pressure, the surface accuracy (cylindricity, etc.) of the bearing surface is lowered, and there is a possibility that a practical slide bearing cannot be obtained.

  The problem to be solved by the present invention is to make a plain bearing that supports a relatively large-diameter shaft member used in office equipment and the like inexpensive and practical.

In order to solve the above problems, the present invention provides a sliding bearing for slidingly supporting a shaft member having a shaft diameter of 6 to 20 mm in a non-lubricated state without interposing a lubricant , and the bearing surface has an inner circumference. An electroformed part formed on the surface and a resin molded product using the electroformed part as an insert part, and a resin part that holds the electroformed part from the outer periphery, and the shrinkage ratio of the material of the resin part is 1% or less There is also provided a plain bearing in which the ratio E ₁ / E ₂ between the Young's modulus E ₁ of the electroformed part and the Young's modulus E ₂ of the resin part is in the range of 5-20.

  As described above, the present inventor has paid attention to the fact that if an electroformed bearing is applied as a slide bearing that supports a shaft member having a shaft diameter of 6 to 20 mm, the cost can be significantly reduced as compared with a rolling bearing. At this time, by making the shrinkage rate of the resin part as small as possible, specifically, 1% or less, deformation of the electroformed part due to molding shrinkage of the resin part can be suppressed.

However, since it is practically impossible to reduce the shrinkage rate of the resin part, it cannot be said that the deformation of the electroformed part can be surely avoided only by suppressing the shrinkage rate. For example, if the hardness (Young's modulus) of the electroformed part is increased, the deformation of the electroformed part can be suppressed, but the cost is increased. Therefore, the present inventor has focused on the fact that the pressure applied to the electroformed part due to molding shrinkage of the resin part is affected not only by the shrinkage rate of the resin part but also by the Young's modulus of the resin part. In other words, by increasing the Young's modulus of the electroformed part rather than simply increasing the Young's modulus of the resin part, the electroformed part is given a minimum hardness that can withstand the pressure caused by molding shrinkage of the resin part. can do. Specifically, if the ratio E ₁ / E ₂ between the Young's modulus E ₁ of the electroformed part and the Young's modulus E ₂ of the resin part is 5 or more, a relatively large-diameter bearing with a shaft diameter of 6 to 20 mm can be used. Even when a cast bearing is applied, it is possible to impart strength to the electroformed part that can withstand the compression force caused by molding shrinkage of the resin part. As a result, it is possible to prevent the deformation of the electroformed part and hence the accuracy of the bearing surface from being lowered while minimizing the cost increase accompanying the improvement of the Young's modulus of the electroformed part. On the other hand, if the above Young's modulus ratio E ₁ / E ₂ is too large, that is, if the resin part is too soft with respect to the hardness of the electroformed part, when the bearing is mounted on an office machine or the like, the shaft rotates. Since the resin portion may be deformed and shaft blurring may occur, the Young's modulus ratio E ₁ / E ₂ needs to be a predetermined value or less, specifically 20 or less.

  The electroformed portion can be formed of, for example, a metal material containing at least one of Ni, Cu, Pd, Cr, Ni—Co alloy, and Sn.

  An electroformed bearing has a bearing surface with excellent dimensional accuracy and surface accuracy by forming a bearing surface on the inner peripheral surface of the electroformed part, that is, the deposition starting surface on the outer peripheral surface of the master. The member can be smoothly rotated. In particular, when used in a non-lubricated state where no lubricant is interposed between the shaft member and the shaft member, it is easy for rattling to occur when rotating the shaft member. It is effective to support the rotating shaft.

  The electroformed part is desirably formed of a material excellent in slidability with the shaft member. For example, the metal used as the base material of the electroformed part is made of a material excellent in slidability (slidability) with the shaft member, and the electroformed part is exposed to the bearing surface by containing a solid lubricant (PTFE or the like). By making it, the slidability in a sliding part with a shaft member can be improved. In this case, among the base metal or solid lubricant that enhances the slidability, those that are not exposed on the bearing surface do not contribute to the improvement of the slidability. Therefore, if the electroformed part has a multi-layer structure, the bearing surface is formed on the inner peripheral surface of the innermost layer, and this layer is made of a material that is more slidable than other layers, the sliding The amount of metal, solid lubricant, and the like that enhances the performance can be minimized, and the material cost can be reduced.

  The plain bearing as described above can be suitably used for supporting the rotating shaft of a roller of office equipment.

  As described above, according to the present invention, a slide bearing that supports a relatively large-diameter shaft member can be made inexpensive and practical.

It is an axial sectional view of a slide bearing. It is a perspective view of the master used at an electroformed part formation process. It is sectional drawing which shows an electroformed part formation process. It is a perspective view which shows the state which made the electroformed part deposit on the outer periphery of a master. It is sectional drawing of the metal mold | die for forming the resin part. It is an axial direction sectional view showing an integrated product of a master, an electroformed part, and a resin part. It is an axial sectional view showing another example of a slide bearing. It is an axial sectional view showing another example of a slide bearing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the plain bearing 1 according to an embodiment of the present invention includes an electroformed part 10 having a bearing surface on an inner peripheral surface, and a resin part 20 that holds the electroformed part 10 from the outer periphery. The bearing 1 supports a shaft member S (shown by a chain line) inserted in the inner periphery on a bearing surface. The shaft member S has a diameter of 6 to 20 mm and is, for example, a rotation shaft of a roller of office equipment. In the present embodiment, a lubricant is not interposed between the bearing 1 and the shaft member S, and when the shaft member S rotates, the bearing surface of the bearing 1 and the outer peripheral surface of the shaft member S are in direct contact sliding. Move.

  The electroformed part 10 is formed of a metal material, for example, a metal material containing at least one of Ni, Cu, Pd, Cr, Ni—Co alloy, and Sn. For example, an additive such as a solid lubricant (PTFE) may be blended in the metal material of the electroformed part 10. In this case, the lubricity with the shaft member S can be improved by exposing PTFE to the bearing surface. In the present embodiment, the electroformed part 10 has a cylindrical shape, and the entire surface of the cylindrical inner peripheral surface 11 serves as a bearing surface. The outer peripheral surface 12 of the electroformed part 10 has a cylindrical surface shape, whereby the thickness of the electroformed part 10 is constant in the axial direction. The thickness of the electroformed part 10 is set within a range of 0.2 to 0.35 mm when the diameter of the shaft member S is 6 to 20 mm as described above.

  The resin part 20 is formed by resin injection molding using the electroformed part 10 as an insert part. In the present embodiment, the resin portion 20 is formed in a cylindrical shape, and the entire surface of the cylindrical outer peripheral surface 12 of the electroformed portion 10 is held by the entire surface of the cylindrical inner peripheral surface 21 of the resin portion 20. The outer peripheral surface 22 of the resin part 20 is also formed in a cylindrical surface shape, whereby the thickness of the resin part 20 is constant in the axial direction.

  As the material of the resin portion 20, a material having a shrinkage rate of 1% or less can be used. Specifically, crystalline resins such as liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), polysulfone (PSF), polyether sulfone (PES) Amorphous resins such as polyphenylsulfone (PPSU) and polyetherimide (PEI) can be used. In the case where the shrinkage rate of these resins alone exceeds 1%, or the shrinkage rate is 1% or less, but the shrinkage rate is further suppressed, the shrinkage rate can be adjusted by adding a filler. Examples of fillers include fibrous fillers such as glass fibers, whisker-like fillers such as potassium titanate, scaly fillers such as mica, carbon fibers, carbon black, graphite, carbon nanomaterials, metal powders, etc. Conductive fillers can be used. These fillers may be used alone or in combination of two or more.

The ratio E ₁ / E ₂ of Young modulus E ₂ of the Young's modulus E ₁ and the resin portion 20 of the electroformed portion 10 is set in the range of 5-20. In other words, the material of the electroformed part 10 and the resin part 20, the additive, or the type and amount of the filler are set so that the Young's modulus ratio E ₁ / E ₂ is in the range of 5-20.

  Hereinafter, the manufacturing process of the slide bearing 1 will be described.

  The slide bearing 1 includes a step of depositing and forming the electroformed portion 10 on the master 30 (electroformed portion forming step, see FIGS. 2 to 4), and injection molding the resin portion 20 using the master 30 and the electroformed portion 10 as insert parts. It is manufactured through a process (resin part molding process, see FIGS. 5 and 6) and a process of separating the master 30 from the slide bearing 1 (master separation process, not shown).

(1) Electroformed portion forming step The master 30 used in this step has a cylindrical outer peripheral surface 31 as shown in FIG. 2, and the cylindrical outer peripheral surface 31 is an inner peripheral surface of the electroformed portion 10. 11 (bearing surface). In the illustrated example, the master 30 is formed in a hollow ring shape having a cylindrical outer peripheral surface 31 and a cylindrical inner peripheral surface 32. In the present embodiment, the electroformed part 10 is formed by electrolytic plating, and for this reason, the master 30 is formed of a conductive material (for example, stainless steel). The material and heat treatment method of the master 30 are appropriately set. For example, the master 30 may be formed of stainless steel, ceramic subjected to a conductive treatment, or the like. The surface of the master 30 (particularly the outer peripheral surface 31) is preferably provided with a fluorine-based resin coating in order to reduce friction when separated from the electroformed part 10.

  Then, as shown in FIG. 3, the plurality of masters 30 are extrapolated to the main electrode 41 and immersed in the electroforming bath 42. Specifically, a flange portion 41 a that protrudes to the outer diameter is provided at the lower end portion of the main electrode 41, and a plurality of masters 30 are stacked on the flange portion 41 a in a state of being extrapolated to the main electrode 41. . Among the plurality of stacked masters 30, the upper surface of the uppermost master 30 and the lower surface of the lowermost master 30 are subjected to a treatment for preventing metal deposition. For example, a hollow disk shape covering these surfaces The covering member 43 is provided. The electroforming bath 42 contains metal ions that form the electroformed portion 10 such as Ni or Cu. Further, the electroforming bath 42 may contain a solid lubricant such as PTFE, a sliding material such as carbon, or a stress relaxation material such as saccharin, if necessary.

  In this state, the power supply 44 energizes between the main electrode 41 and the sub-electrode 45 disposed around the main electrode 41. Thereby, the outer peripheral surface 31 of the master 30 deposits a metal material, and the electroformed part 10 is formed (refer FIG. 4). The thickness of the electroformed part 10 is set by appropriately adjusting the energization time and the current value at this time.

  The electroformed part 10 does not necessarily have to be deposited by electrolytic plating, but may be performed by electroless plating in which a metal is deposited without energizing the solution. In this case, the master 30 does not need to have conductivity, and may be formed of a non-conductive material.

(2) Resin part molding process The integral part of the electroformed part 10 and the master 30 formed in the above process is placed in a mold. As shown in FIG. 5, the mold includes a fixed mold 51 and a movable mold 52, and an inner peripheral surface of the master 30 is fitted to a pin 53 provided on the fixed mold 51. In this state, the mold is clamped, and the molten resin is injected into the cavity 55 through the gate 54, whereby the resin portion 20 is integrally formed with the electroformed portion 10.

(3) Separation process When the resin is solidified, the mold is opened, and an integrated product (see FIG. 6) of the slide bearing 1 (electroformed part 10 and resin part 20) and the master 30 is taken out from the mold, and the master 30 is removed from the integrated product. Isolate. In this separation step, the master 30 is separated from the slide bearing 1 by pulling out the master 30 with a jig or the like while the slide bearing 1 is fixed, and the slide bearing 1 shown in FIG. 1 is obtained.

As described above, the sliding bearing 1 of the present invention has a shrinkage ratio of the resin material of the resin portion 20 of 1% or less, and a Young's modulus E ₁ of the electroformed portion 10 and a Young's modulus E _{2 of the} resin portion 20. Since the ratio E ₁ / E ₂ is 5 or more, deformation of the electroformed part 10 due to molding shrinkage of the resin part 20 is suppressed. Therefore, since the inner peripheral surface 11 of the electroformed part 10 is not pressed against the outer peripheral surface of the master 30 due to the molding shrinkage of the resin part 20, the master 30 can be easily separated and the electric power is separated after the master 30 is separated. It can prevent that the casting part 10 deform | transforms.

  The present invention is not limited to the above embodiment. Hereinafter, other embodiments of the present invention will be described, but the same reference numerals are given to portions having the same configuration and function as those of the above-described embodiments, and description thereof will be omitted.

  The sliding bearing 101 shown in FIG. 7 is different from the above embodiment in that the electroformed part 110 has a multi-layer structure. Specifically, the electroformed portion 110 includes a cylindrical inner electroformed layer 111 having an inner peripheral surface 111a as a bearing surface, and a cylindrical outer electroformed layer 112 provided outside the inner electroformed layer 111. It has a two-layer structure. In the outer electroforming tank 112, the inner peripheral surface 112 a is in close contact with the outer peripheral surface 111 b of the inner electroforming tank 111, and the outer peripheral surface 112 b is in close contact with the inner peripheral surface 21 of the resin portion 20. The inner electroformed layer 111 is formed of a material that is more slidable with the shaft member than the outer electroformed layer 112. For example, a solid lubricant is blended in the material of the inner electroformed layer 111.

  In this way, by blending the solid lubricant in the inner electroformed layer 111, the solid lubricant is exposed from the inner peripheral surface 111a (bearing surface) of the inner electroformed layer 111 serving as the bearing surface, and slides on the shaft member. Improve mobility. Further, by not blending the outer electroformed layer 112 with a solid lubricant, the amount of the solid lubricant used can be minimized, and the material cost can be reduced.

  The slide bearing 101 is manufactured as follows. First, the master is immersed in an electroforming bath containing metal ions and a solid lubricant, and the inner electroformed layer 111 is deposited on the outer peripheral surface of the master. Thereafter, the master and inner electroformed layer 111 are taken out from the electroforming bath and immersed in another electroforming bath, and the outer electroformed layer 112 is deposited on the outer peripheral surface of the inner electroformed layer 111. Subsequent steps are the same as described above, and therefore redundant description is omitted.

  The slide bearing 201 shown in FIG. 8 is different from the above embodiment in the shape of the resin portion 220. Specifically, the resin portion 220 has a cylindrical surface-shaped small-diameter inner peripheral surface 221 that holds the outer peripheral surface 12 of the electroformed portion 10, and a large-diameter inner peripheral surface provided on one axial direction of the small-diameter inner peripheral surface 221. 222 and a flange portion 223 extending from one end portion in the axial direction toward the outer diameter. The flange portion 223 is a portion that is fixed to a member on the office equipment side when attached to the office equipment or the like. In the resin part 220, the thickness is constant in the axial direction region where the electroformed part 10 is held.

  In the above embodiment, the case where the slide bearing is used in a non-lubricated state is shown. However, the present invention is not limited to this, and in the bearing gap between the bearing surface of the slide bearing 1 and the outer peripheral surface of the shaft member S, A lubricant (for example, lubricating oil) may be interposed. In this case, a dynamic pressure generating portion (for example, a herringbone-shaped or step-shaped dynamic pressure groove) that positively generates a dynamic pressure action on the lubricating film formed in the bearing gap is provided on the inner peripheral surface of the electroformed portion 10. 11 may be formed.

  Moreover, although the case where a slide bearing is used for supporting the rotating shaft of a roller for office equipment is shown in the above embodiment, the present invention is not limited to this, and it may be used for supporting a shaft member having a diameter of 6 to 20 mm. The sliding bearing of the present invention can be suitably applied.

DESCRIPTION OF SYMBOLS 1 Slide bearing 10 Electroformed part 20 Resin part 30 Master 41 Main electrode 42 Electroforming bath 43 Power supply 44 Subelectrode 51 Fixed mold 52 Movable mold 53 Pin 54 Gate 55 Cavity S Shaft member

Claims (4)

A slide bearing for slidingly supporting a shaft member having a shaft diameter of 6 to 20 mm in a non-lubricated state without interposing a lubricant ,
An electroformed part having a bearing surface formed on the inner peripheral surface, and a resin molded product using the electroformed part as an insert part, and a resin part that holds the electroformed part from the outer periphery,
Slipping in which the shrinkage ratio of the material of the resin part is 1% or less, and the ratio E ₁ / E ₂ between the Young's modulus E ₁ of the electroformed part and the Young's modulus E ₂ of the resin part is in the range of 5-20. bearing.   The plain bearing according to claim 1, wherein the electroformed part is formed of a metal material containing at least one of Ni, Cu, Pd, Cr, Ni—Co alloy, and Sn. Cast part form a multi-layer structure conductive, most on the inner peripheral surface of the inner diameter side of the layer to form a bearing surface, according to claim 1 or to form the layer of a material excellent in sliding property than the other layers 2. A plain bearing according to 2 . The plain bearing according to any one of claims 1 to 3 , which is used for supporting a rotating shaft of a roller for office equipment.

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