JP2007187260A - Resin pulley - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin pulley capable of achieving both of high accuracy in molding an outside diameter portion and abrasion resistance. <P>SOLUTION: In this resin pulley comprising a rolling bearing and a resin portion formed around the rolling bearing integrally therewith, the resin portion is composed of a polyamide resin composition including glass fiber having a modified cross-section by 20-60 wt.%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin pulley, and more particularly to a resin pulley used as a driving belt for auxiliary equipment mounted on an automobile, a tensioner for other belts, an idler pulley, or the like.

  2. Description of the Related Art Conventionally, resin pulleys formed by integrally molding resin on the outer periphery of a rolling bearing have been adopted as guide pulleys for belts that drive automobile auxiliary machinery. Resin pulleys are required to have molding accuracy of the outer diameter portion that guides the belt, strength characteristics that can withstand belt tension, heat resistance by using a continuous load, resistance to calcium chloride, and the like.

  Therefore, as such a resin material for improving molding accuracy, strength, heat resistance and calcium chloride resistance, reinforced nylon 66, reinforced nylon 610, reinforced nylon 612, or polyphenylene sulfide filled with about 15 to 40% by weight of glass fiber. And mineral composite materials, and resin pulleys using polyamide resins such as 6 nylon, 66 nylon, 11 nylon, and 12 nylon containing 43% by weight of glass fiber have been proposed. The glass fiber contained in such a resin material has a circular cross section with a diameter of 10 to 13 μm (see, for example, Patent Documents 1 and 2).

JP-A-7-63249 JP-A-8-4883

  However, the polyamide-based material reinforced with the glass fiber having the circular cross section is excellent in heat resistance and fatigue resistance, but the molding accuracy of the outer diameter portion of the molded product is poor and is not sufficiently satisfactory. In particular, when the roundness of the outer diameter part (the amount of unevenness on the outer diameter circumferential surface of the resin part) is large or the unevenness existing on the outer diameter part surface is large, when the belt is rotated as a result There was a problem in use because the level of generated sound increased.

  Also, if the resin pulley has sand dust in between it and the belt when traveling on rough roads, the outer surface of the outer diameter part will be worn and the unevenness will increase, or the wear will progress and the outer diameter of the pulley will increase. If it becomes smaller, there is a possibility that the belt may come off. Such wear is presumed to start when the wear progresses from a portion other than the filler present on the pulley surface and the surface of the outer diameter portion becomes rough.

  This invention is made paying attention to such a situation, and it aims at providing the resin-made pulley which achieved the high precision of the shaping | molding precision of an outer-diameter part, and the wear-resistant improvement collectively. .

  To achieve the above object, the present invention provides a resin pulley comprising a rolling bearing and a resin portion integrally formed with the rolling bearing around the rolling bearing, wherein the resin portion has an irregular cross section. A resin pulley comprising a polyamide resin composition containing 20 to 60% by weight of glass fiber is provided.

  The resin pulley of the present invention uses a glass fiber having an irregular cross section as a reinforcing material, so that the mechanical strength is higher than when a conventional glass fiber having a circular cross section is used, and the wear resistance is improved. Furthermore, the surface of the outer diameter cylindrical portion becomes smoother and the sound pressure level when the belt is driven is lowered.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing an embodiment of a resin pulley according to the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG.

  1 and 2, the resin pulley includes a rolling bearing 1 and a resin portion 2 formed integrally with the rolling bearing 1 around the rolling bearing 1. The resin portion 2 is formed between the inner diameter cylindrical portion 3 fixed to the outer ring of the rolling bearing 1, the outer diameter cylindrical portion 5 having the belt guide surface 4, and the outer diameter cylindrical portion 5 and the inner diameter cylindrical portion 3. And a plurality of ribs 7 are formed radially on the disk portion 6. In addition, a large number of gates 8 are formed at equal intervals in a predetermined pitch circle in the inner diameter cylindrical portion 3, and molten resin is poured into these gates 8, and a resin pulley is manufactured by injection molding.

  As shown in FIG. 2, the rolling bearing 1 is a deep groove ball bearing with a contact rubber seal having a concave groove 9 that prevents the resin part 2 from being attached to and detached from the outer ring outer peripheral part. As a rubber material of the contact rubber seal 10, a material made of nitrile rubber, hydrogenated nitrile rubber, acrylic rubber or the like and blended with various fillers can be used. In addition, the grease filled in the rolling bearing 1 is based on poly α-olefin oil, alkyl diphenyl ether oil, etc., base oil, diurea etc. as a thickener, and an antioxidant as an additive in consideration of operating temperature. In addition, those to which an antiwear agent is further added are mainly used.

  The resin part 2 consists of the resin composition which mix | blended the glass fiber which has a deformed cross section as a reinforcing material with the resin material. As the resin material, it is preferable to use a polyamide resin such as polyamide 6, polyamide 66, or polyamide 46, which has excellent fatigue resistance, as the base resin. The molecular weight of the base resin is preferably 13,000 to 30000 in terms of number average molecular weight in view of injection moldability, and is preferably in the range of 18000 to 25000 in terms of number average molecular weight in consideration of fatigue resistance and high molding accuracy. When the number average molecular weight is less than 13,000, the molecular weight is too low, the fatigue resistance is low, and there is no practicality. On the other hand, when the number average molecular weight exceeds 30000, fatigue resistance is improved, but when a specified amount of glass fiber having an irregular cross section is included to achieve mechanical strength such as impact strength necessary for the pulley, The melt viscosity at that time becomes high, and it becomes difficult to produce a pulley with high accuracy by injection molding.

  In addition, in order to reduce the water absorption and improve the calcium chloride resistance, these base resins may be combined with other polyamide resins with low water absorption or polyolefin resins modified with acid anhydrides, You may combine rubber-like substances, such as ethylene propylene nonconjugated diene rubber (EPDM) which improves impact property.

  Specific examples of the low water-absorbing polyamide resin may include polyamide 12, polyamide 11, polyamide 612, polyamide 610, polyamide 6I6T, polyamide MXD6, modified polyamide 12, and modified polyamide 6T. The mixing amount of these low water-absorbing polyamide resins is 10 to 50% by weight with respect to 50 to 90% by weight of the high water-absorbing polyamide resins such as polyamide 6, polyamide 66, and polyamide 46. Among the above-mentioned low water-absorbing polyamide resins, the modified polyamide 12 is particularly preferable because it is non-crystalline and has high compatibility with the high water-absorbing polyamide resin and the mechanical strength does not decrease by mixing. . These low water-absorbing polyamide resins may be used as a mixture of two or more. In that case, when the modified polyamide 12 and another low water-absorbing polyamide resin are combined, the modified polyamide 12 serves as a compatibilizing agent. It functions, and the mechanical strength is not reduced by mixing, which is preferable.

  The glass fiber having an irregular cross section need not be circular in cross section, and for example, a glass fiber having a cross section such as an eyebrow shape, an ellipse, or an ellipse can be used. Preferably, it is a glass fiber having a deformed ratio (ratio of the major axis part to the minor axis part) of 1.5 to 5, and more preferably a glass fiber of 2 to 4. If the profile ratio is less than 1.5, the effect of improving the mechanical strength is small, and if the profile ratio exceeds 5, it is too flat and it is difficult to produce stably. Moreover, it is preferable that a short diameter part is 5-12 micrometers. If the short diameter part is less than 5 μm, it is too thin and breaks or breaks during production. Therefore, it is difficult to maintain a stable quality at low cost, and the practicality is low. On the other hand, when the minor axis part exceeds 12 μm, the fiber is too thick considering the profile ratio, and the dispersibility in the resin becomes inferior, which may cause unevenness in strength.

  Content of the glass fiber which has an irregular cross section is 20-60 mass% of the resin composition whole quantity, Preferably it is 25-50 mass%. When the content is less than 20% by mass, the reinforcing effect is small. When the content exceeds 60% by mass, not only fluidity suitable for injection molding can be obtained, but also the outer diameter cylindrical part 5 and the rib 7 present in the cross-sectional part are provided. It becomes difficult to mold with high accuracy.

  The glass fiber having an irregular cross section used in the present invention is less likely to break than a conventional glass fiber having a circular cross section, and is dispersed in the resin in a longer state than the glass fiber having a circular cross section when kneaded with a base resin and injection molded. To do. Therefore, when compared with the same content, the effect of increasing mechanical strength such as tensile strength and impact strength is superior to that of glass fibers having a circular cross section. In addition, since the glass fiber having an irregular cross section is oriented so as to be parallel to the outer surface of the outer diameter cylindrical portion 5 during molding, wear due to sliding with the belt is reduced. Furthermore, in addition to the reinforcing effect in the length direction of the fiber, a slight reinforcing effect also appears in the direction of the short diameter portion, so that the entire pulley has a reinforcing effect, and the effect of suppressing the dimensional change due to water absorption is increased, and the outer diameter cylinder The roundness of the portion 5 is increased, and the surface irregularities are also reduced.

  In addition, the glass fiber having an irregular cross-section is a silane coupling agent having an epoxy group or an amino group at one end, or a sizing agent such as an epoxy type, a urethane type, or an acrylic type in consideration of adhesiveness with the base resin. It is preferable to use a surface-treated product. Silane coupling agents and sizing agents are selected according to the type of base resin. For example, silane coupling agents having an epoxy group or amino group have an epoxy group or amino group acting on the amide bond of the polyamide resin. Improve the reinforcement effect.

  In addition, it is preferable that the glass fiber which has a deformed cross section has a fiber length of 300-900 micrometers in the resin pulley obtained, and it is more preferable that it is a fiber length of 350-600 micrometers. If the fiber length is less than 300 μm, the reinforcing effect and the dimensional stability effect are small, which is not preferable. On the other hand, it is difficult to maintain a long fiber state exceeding 900 μm in the process of kneading with the base resin and injection molding, and the upper limit of the fiber length is a value set from the manufacturing process. In order to obtain such a fiber length, kneading conditions and molding conditions may be adjusted.

  A part of the glass fiber having an irregular cross section may be replaced with another fibrous reinforcing material such as carbon fiber or a whisker-like reinforcing material such as potassium titanate whisker.

  A colorant or the like may be further added to the resin composition. In order to improve heat dissipation, a high thermal conductive filler having a thermal conductivity of 10 W / m · K or more, specifically, alumina, magnesia, aluminum nitride, silicon carbide, beryllia, graphite, etc. are further added. May be. Furthermore, in order to further reduce the unevenness of the outer diameter cylindrical portion 5 or to further improve the wear resistance of the outer diameter cylindrical portion 5, a particulate filler, specifically, calcium carbonate, clay, talc, silica, Wollastonite or the like may be added. As the particulate filler, if the above-described highly thermally conductive filler is also particulate, the same effect is obtained. Moreover, in order to prevent deterioration due to heat during molding and use, it is preferable to add an iodide heat stabilizer and an amine antioxidant to the resin material, either alone or in combination.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1
Polyamide 66 ("UBE Nylon 2026U" manufactured by Ube Industries, Ltd., number average molecular weight 26000, containing copper iodide-based additive) 70% by mass, oblong glass fiber ("CSG 3PA-820" manufactured by Nittobo Co., Ltd.) ”, Profile ratio 4, minor axis portion 7 μm, urethane sizing agent treatment) 30% by mass of resin composition, deep groove ball bearing with contact rubber seal (6203DDL18) having a concave groove on the outer ring outer peripheral portion as a core, Insert molding (injection molding) was performed on the space formed between the outer ring and the mold to obtain a resin pulley.

(Example 2)
A resin pulley was obtained in the same manner as in Example 1 except that polyamide 46 ("Stanyl TW341" manufactured by DJEP, containing a copper heat stabilizer) was used as the base resin.

(Example 3)
As a base resin, 1: 1 of polyamide 66 (“UBE nylon 2026U” manufactured by Ube Industries, Ltd., number average molecular weight 26000, containing copper iodide-based additive) and polyamide 612 (“Vestamide DX9301” manufactured by Daicel Defusa Co., Ltd.) A resin pulley was obtained in the same manner as in Example 1 except that the mixture was used.

(Comparative Example 1)
Glass fiber-containing polyamide 66 (“UBE nylon 2020GU6” manufactured by Ube Industries, Ltd., containing a number average molecular weight of 20,000, containing a copper iodide-based additive, containing 30% by mass of glass fiber treated with a silane coupling agent having a diameter of 13 μm), A deep groove ball bearing (6203DDL18) with a contact rubber seal having a groove on the outer ring outer peripheral part is used as a core, and insert molding (injection molding) is performed in a space formed between the outer ring of the bearing and a mold, and a resin pulley Got.

[Outside cylindrical part forming accuracy evaluation]
About each resin pulley of Examples 1-3 and Comparative Example 1, the unevenness | corrugation amount in the intermediate height of an outer diameter cylindrical part was measured. The measurement results are shown in Table 1.

[Abrasion resistance evaluation of outer cylindrical part]
FIG. 3 shows the configuration of the wear resistance tester 42 used in this wear resistance test. The abrasion resistance tester 42 includes a drive wheel 44 and a driven wheel 46 connected to a drive motor (not shown). A belt 48 is stretched over and connected to the driving wheel 44 and the driven wheel 46. The resin pulley 11 to be tested can be attached between the driving wheel 44 and the driven wheel 46 while the belt guide surface 31 is in contact with the belt 48. A load of 980 N is applied downward to the rolling bearing of the resin pulley 11, and the belt guide surface 31 of the resin pulley 11 is pressed against the belt 48 by this load. When the driving wheel 44 rotates, the driven wheel 46 is driven to rotate via the belt 48, and the belt guide surface 31 pressed against the belt 48 is rotated. Further, in the abrasion resistance tester 42, the atmosphere in the thermostatic chamber 50 is maintained at 120 ° C. In this atmosphere, Kanto loam powder JIS # 8 satisfies the condition of 0.02% in space volume. It is drifted by fans. The atmosphere in the thermostat 50 reproduces that the resin pulley used for the auxiliary machinery of the automobile is traveling on a rough road.

Then, each of the resin pulleys of Examples 1 to 3 and Comparative Example 1 was attached to the abrasion resistance tester 42 and rotated at 8000 min ⁻¹ . After rotating for 100 hours, the wear resistance tester 42 is stopped, the resin pulley is cooled to room temperature, and the radial wear amount of the belt guide surface 31 of the resin pulley 11 is determined by the reference position (the central portion in the axial direction). ). The amount of wear is also shown in Table 1.

  As is clear from Table 1, by using glass fibers having a modified cross section, the decrease in anisotropy and the amount of irregularities in the outer diameter portion are reduced due to the orientation of the glass fibers parallel to the surface of the outer diameter cylindrical portion 5. It was found that the wear resistance was improved.

  In addition, in this embodiment, it is not limited to embodiment mentioned above, A change, improvement, etc. are possible suitably. In the above embodiment, the outer peripheral cylindrical portion has been described with respect to a flat resin pulley, but the outer peripheral cylindrical portion 5 as shown in FIG. 4 is formed separately from a V-ribbed resin pulley or a rolling bearing. The present invention can also be applied to a resin pulley having a configuration.

It is a front view showing one embodiment of a resin pulley concerning the present invention. It is the sectional view on the AA line of FIG. It is the schematic of the testing machine for investigating abrasion resistance. It is sectional drawing of the resin pulley concerning the modification of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolling bearing 2 Resin part 3 Inner diameter cylindrical part 4 Belt guide surface 5 Outer diameter cylindrical part

Claims (1)

  In a resin pulley comprising a rolling bearing and a resin portion integrally formed with the rolling bearing around the rolling bearing, the resin portion contains 20 to 60% by weight of a glass fiber having a modified cross section. A resin pulley comprising the composition.

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