JP2006083927A - Bearing integration type synthetic resin pulley - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light weight bearing integration type synthetic resin pulley by insert forming not generating noise and vibration by preventing both of roughness of a belt guide surface and eccentricity at a time of insert forming and avoiding complication of operation and cost increase due to that. <P>SOLUTION: In the bearing integration type synthetic resin pulley fixing a synthetic resin pulley on an outer ring outer circumference surface of a rolling bearing by insert forming, problems are solved by the bearing integration type synthetic resin pulley of which outer circumference surface of the synthetic resin pulley is machined. The bearing integration type synthetic resin pulley including an outer tube part, an inner tube part and a connection part connecting the outer tube part and the inner tube part and radially provided with a plurality of reinforcement ribs on both side surfaces of the connection part over circumference direction with a predetermined interval is suitable. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to a bearing-integrated synthetic resin pulley, and more particularly, to apply a desired tension to a belt or timing belt tensioner or idler for driving an auxiliary machine of an automobile engine or a camshaft. The present invention relates to a bearing-integrated synthetic resin pulley.

  Conventionally, a bearing-integrated synthetic resin pulley has been widely used as a pulley for applying a desired tension to a belt for driving an auxiliary machine of an automobile engine or a camshaft or a timing belt. Synthetic resin pulleys can be reduced in weight and cost as compared with metallic pulleys, but have a problem that they are weak in strength.

  As shown in FIGS. 5A and 5B, the structure of the bearing-integrated synthetic resin pulley Puz currently used is composed of a ball bearing Tz and a resin pulley 6z fixed to the outer periphery of the ball bearing. Yes.

  The resin pulley 6z includes an inner cylindrical portion 62z whose inner peripheral surface 620z is fixed to the outer ring 1z of the ball bearing Tz, an outer cylindrical portion 61z whose outer peripheral surface 610z serves as a belt guide surface, and a connecting portion 63z that connects the inner and outer cylindrical portions. In order to reinforce the strength of the outer cylindrical portion 61z in the radial direction, the connecting portion 63z is radially provided on both surfaces of the connecting portion 63z at equal intervals in the circumferential direction. It has a shape that corresponds to weight reduction, cost reduction, and reinforcement.

  In the injection molded product, after molding, due to the difference in cooling time between the surface portion and the inside, a difference in volume shrinkage time is caused between the surface portion and the inside, and the deformation which is said to be attracted partially occurs. If deformation such as irregularities occurs due to the pulling on the outer peripheral surface that becomes the belt guide surface of the pulley, it becomes a shape that is not suitable as a guide surface, which may cause vibrations or abnormal noise, or cause a problem of slippage with the belt.

In order to reduce the occurrence of shrinkage in the case of injection molding as much as possible, the current pulley is devised such that the thickness dimensions of the inner cylindrical portion 62z, the outer cylindrical portion 61z, the connecting portion 63z, and the reinforcing rib 66z are as approximate as possible. Yes. However, even with such a contrivance, in the circumferential direction of the outer peripheral surface 610z, the outer peripheral surface 610z where the reinforcing rib 66z is present inward and the outer peripheral surface 610z where the reinforcing rib 66z does not exist are different in degree of deformation and uneven Therefore, when the number of reinforcing ribs increases, the number of irregularities increases. These irregularities are small, but even with these small irregularities, the rotational speed and load of the pulley tend to increase in the future. May be a problem. For example, the content of Patent Document 1 has been proposed as a proposal for improving the close problem.
JP-A-10-122339

  However, Patent Document 1 is an effective measure for the problem of shrinkage, but does not mention the problem of vibration and noise caused by the small unevenness described above. Furthermore, another problem of pulley noise, vibration, and slip is the problem of eccentricity between the rotation center of the bearing caused by insert molding and the pulley outer peripheral surface serving as the belt guide surface, and this problem is not mentioned.

  The case where the bearing-integrated synthetic resin pulley is molded by injection molding will be described with reference to FIG.

A ball bearing Tz is arranged at a predetermined position in a mold composed of an upper mold U ₁ z and a lower mold L ₁ z, and molten resin is poured into a pulley-shaped cavity Cz formed in the mold, thereby A bearing-integrated synthetic resin pulley Puz in which the resin pulley 6z is fixed to the outer ring is molded. FIG. 6 shows the state after the resin is injected into the cavity.

At this time, the core pins U ₂ z and L ₂ z are used to arrange and fix the rolling bearings at predetermined positions of the mold. Since the fitting of the core pin and the inner ring of the bearing needs to be loosely fitted for work, an eccentricity is generated between the inner ring of the bearing and the outer peripheral surface of the resin pulley to be molded by the clearance. This eccentricity causes vibration, abnormal noise, and slip due to rotation.

  Further, when the molten resin injected into the cavity portion 63zc for molding the pulley coupling portion 63z and the cavity portion 66zc for molding the reinforcing rib 66z is cooled after molding, the outer cylindrical portion 61z molded by the cavity portion 61zc Small irregularities are generated on the outer peripheral surface 610z by shrinkage. This small unevenness may also become a problem in the future due to vibration and abnormal noise.

  In order to prevent both the unevenness of the belt guide surface caused by the above-mentioned shrinkage and the problem due to the eccentricity at the time of insert molding, grasp the molding processing characteristics of the resin material, manufacture precise and complicated molds, and strictly the molding conditions Management is required. In addition, the work at the time of molding is complicated, resulting in an increase in cost and time.

  The present invention has been made in view of the above points, and without requiring grasping of molding processing characteristics of a resin material, production of a precise and complicated mold, strict control of molding conditions, and the like. Lightweight bearing-integrated synthetic resin by insert molding that prevents both small unevenness and eccentricity at the time of insert molding, does not cause abnormal noise and vibration, and avoids complicated work and cost increase The purpose is to provide a pulley.

In order to achieve the above object, the present invention provides:
Outer ring,
Inner ring,
A plurality of rolling elements interposed between the outer and inner rings;
In a bearing-integrated synthetic resin pulley in which a synthetic resin pulley is fixed to the outer peripheral surface of an outer ring of a rolling bearing consisting of insert molding,
Provided is a bearing-integrated synthetic resin pulley characterized in that the outer peripheral surface of the synthetic resin pulley is a machined surface.

The present invention also provides:
Furthermore, the synthetic resin pulley has an outer cylindrical portion, an inner cylindrical portion, and a connecting portion that connects the outer cylindrical portion and the inner cylindrical portion, and the outer cylindrical portion is provided on both sides of the connecting portion. It is preferable to provide a plurality of reinforcing ribs that reinforce the strength in the radial direction in a radial pattern at predetermined intervals in the circumferential direction.

  According to the present invention, the unevenness of the belt guide surface and the eccentricity at the time of insert molding can be achieved without the need to grasp the molding processing characteristics of the resin material, manufacture a precise and complicated mold, and strictly control the molding conditions. It is possible to provide a lightweight bearing-integrated synthetic resin pulley by insert molding which prevents both of them, does not cause abnormal noise and vibration, and avoids complicated work and cost increase.

  Embodiments according to the present invention will be described below with reference to the drawings.

(Embodiment 1)
A bearing-integrated synthetic resin pulley Pu according to Embodiment 1 of the present invention will be described with reference to FIG.
This figure shows a cross-sectional view of the present embodiment.
In the bearing-integrated synthetic resin pulley Pu, a synthetic resin pulley 6 is fitted and fixed to the outer ring 1 of the ball bearing T.

  The outer ring 1 of the ball bearing T has an inner circumferential track 1a on the inner circumferential portion and a circumferential groove 11 inclined on the outer circumferential surface by a predetermined angle θ with respect to a plane perpendicular to the rotation center XX. ing.

  The inner ring 2 has an outer peripheral track 2a facing the inner peripheral track 1a of the outer ring on the outer peripheral portion.

  A plurality of balls 3 are interposed between the inner race 1a of the outer ring and the outer race 2a of the inner ring to allow relative rotation of the outer inner race.

  The cage 4 holds the ball 3.

  The seal 5 seals the space of the inner and outer rings at both ends of the ball bearing T.

  The resin pulley 6 includes an outer cylindrical portion 61, an inner cylindrical portion 62, and a connecting portion 63 that connects both cylindrical portions. An outer peripheral surface 610 of the outer cylindrical portion 61 is a belt guide surface. The inner peripheral surface 620 of the inner cylindrical portion 62 is fitted and fixed to the outer peripheral surface of the outer ring 1. Both side surfaces 64 of the connecting portion 63 are flat surfaces, and large spaces are provided on both sides thereof to serve as escape portions 65 for weight reduction. The thickness of the connecting portion 63 can be selected so as to maintain the strength against the load received when guiding the belt while a load is applied to the belt on the outer peripheral surface 61 in relation to the thickness of the outer cylindrical portion. . The outer peripheral surface 610 is finished to a machined surface such as cutting or grinding with a grindstone with the rotation center XX as a reference. for that reason. The amount of eccentricity of the outer peripheral surface 610 based on the rotation center XX can be managed small. In particular, grinding can ensure a precision of several microns.

  The inner peripheral surface 62 has both end annular projections 621 protruding inward from the inner peripheral surface at both ends, and secures the outer ring 1 and the resin pulley 6 in the axial direction. In addition, a central annular protrusion 622 that is inclined by a predetermined angle θ with respect to the rotation center XX is formed at a substantially central portion in the axial direction of the inner peripheral surface 62. As will be described later, the center annular protrusion 622 is formed as a result of the resin melted during the insert molding being injected into the circumferential groove 11 of the outer ring, and is a fitting surface caused by the difference in linear expansion coefficient between the outer ring and the resin. Prevents circumferential creep.

  Next, the insert molding of the bearing-integrated synthetic resin pulley will be described with reference to FIG.

  FIG. 2 is a partial cross-sectional view of a mold for insert molding according to the present embodiment, and shows a state in which resin has already been injected into the mold.

The ball bearing T is composed of an upper mold U ₁ and a lower mold L ₁ and is disposed in an upper core pin part U ₂ and a lower core pin part L ₂ of an insert molding die having a cavity C between both molds. Molten resin is injected into the cavity C from an injection portion (not shown). The cavity C has the same shape as the resin pulley. The difference between the outer diameter of both core pins and the inner diameter of the inner ring is set so that a clearance of several microns to several tens of microns is obtained from the viewpoint of workability. After the injection molding, the injected resin in the cavity is cooled first from the portion close to the mold, and the portion far from the mold, that is, the inside is cooled slowly. For this reason, deformation (squeezing) of the previously cooled portion occurs after the completion of molding. Since deformation (shrinkage) occurs on the outer peripheral surface serving as the belt guide surface, after molding, the belt is eccentric and deformed. Since resin is injected into the circumferential groove 11 of the outer ring on the inner peripheral surface of the resin pulley 6, a central annular protrusion 622 is formed.

  The present embodiment shown in FIG. 1 is obtained by correcting the above-described inappropriate shapes such as eccentricity and unevenness by a method such as cutting or grinding of the outer peripheral surface with reference to the rotation center XX after injection molding.

  In this embodiment, since the outer peripheral surface 610 of the resin pulley 6 is cut or ground after injection molding, both the unevenness of the belt guide surface caused by shrinkage and the problem due to eccentricity at the time of insert molding can be prevented. There is no need to understand the molding characteristics of materials, manufacture precise and complex molds, and strictly control molding conditions. In addition, there is no complicated work during molding, and no increase in cost and time.

  Next, Modification 1 will be described with reference to FIGS. 3 (a) and 3 (b).

  FIG. 3A shows a front view of this modification. FIG.3 (b) has shown sectional drawing of arrow AA of Fig.3 (a).

  The bearing-integrated synthetic resin pulley Pu of the present modification includes an outer cylindrical portion 61 whose outer peripheral surface is a belt guide surface, an inner cylindrical portion 62 whose inner peripheral surfaces are concentrically fixed to the outer ring of the bearing, It is comprised from the annular connection part 63 which connects a cylindrical part. In order to reinforce the strength of the outer cylindrical portion 61 in the radial direction, the connecting portion 63 has a structure in which a plurality of reinforcing ribs 66 having a predetermined thickness are provided radially at equal intervals in the circumferential direction on both side surfaces of the connecting portion. Therefore, it has a shape corresponding to weight reduction, cost reduction, and reinforcement. A space 67 is formed between the reinforcing ribs 66 to further reduce the weight of the pulley. The connecting portion 63 is formed integrally with the outer cylindrical portion 61, the inner cylindrical portion 62 and the connecting portion 63. The circumferential positions of the reinforcing ribs 66 provided on both side surfaces are made to coincide with each other. The number of reinforcing ribs can be set as appropriate.

  In the case of this modification, the unevenness generated on the outer peripheral surface after molding is an unevenness generated due to the difference in the degree of deformation in the circumferential direction where the reinforcing rib 66 is present and where there is no reinforcing rib 66. The unevenness is small, and the time required for correction by machining is short.

  In this modification, the reinforcing ribs 66 are aligned with each other in the circumferential direction. However, the phase may be appropriately changed on both side surfaces.

  The method shown in FIG. 2 can be used for fixing the resin pulley 6 and the ball bearing T by insert molding. However, in the case of this modification, it is natural that the cavity shape of the mold is the shape of the pulley of this modification. Further, the fixation between the outer peripheral portion of the outer ring and the inner peripheral portion of the pulley is the same as in the first embodiment. Furthermore, after the resin pulley and the bearing are integrated by insert molding, the outer peripheral portion of the pulley is machined, such as grinding or cutting, in the same manner as in the embodiment.

In addition, description is abbreviate | omitted about the same site | part and Embodiment 1 as Embodiment 1. FIG.
Next, an experiment conducted for confirming the effect of the present invention will be described with reference to FIG.

  The test product used in this test has the same structure as the bearing-integrated synthetic resin pulley shown in the first modification, and is a product of the present invention.

  External diameter of resin pulley; 70 mm, resin material; glass fiber reinforced polyamide 66 (trade name, Amilan CM3006G-30), molding conditions; mold adjusted to a temperature of 100 ° C. with the resin melted Was injected at an injection pressure of 100 MPa.

  After the molten resin was cooled and solidified, the molded product was taken out, and the pulley outer peripheral surface was cut based on the inner diameter of the bearing to obtain a test product.

The test machine shown in FIG. 4 was used for this test. In this testing machine, a belt B is stretched between a driving wheel D ₁ and a driven wheel D ₂ fixed to a pair of rotating shafts, and a test pulley Tp is pressed against a part of the outer peripheral surface of the belt B by a load F. . In this test pulley, an inner ring of a ball bearing T is externally fixed to a support shaft that is supported so as to be displaceable with respect to a fixed portion (not shown). As the test pulley Tp, the above-mentioned product and the resin pulley of the comparative example were incorporated. The sound pressure (dB) at a position 100 mm away from the test product and the comparative example was measured. Rotational speed S: 5000 r. p. m / min, pressing load F; 1200N. The sound pressure measuring instrument is “SOUND LEVEL METER RION NA-24”.

  The test results are as shown in Table 1, and the product of the present invention has a lower sound pressure than Comparative Examples 1 and 2.

As described above, the effect of the product of the present invention has been described. As the resin material constituting the resin pulley of the present invention, polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 46, polyamide 610, polyamide 612, aromatic Aromatic polyamide having a ring, non-changing polyamide having a cyclo ring, or a mixture of a plurality of non-changing polyamides, polyphenylene sulfide (PPS), reinforced fiber such as glass fiber based on phenol resin, mineral such as talc, mica, etc. A composite material to which a filler is added can be used.

It is sectional drawing which shows Embodiment 1 of this invention. It is explanatory drawing of insert molding of Embodiment 1. FIG. (a) is a front view showing a first modification.

(b) is sectional drawing seen from arrow AA of (a).
It is explanatory drawing of the testing machine which confirms the effect of this invention. (a) is a front view which shows a prior art example.

(B) is sectional drawing seen from arrow AA of (a).
It is explanatory drawing of the insert molding of a prior art example.

Explanation of symbols

Pu: Bearing-integrated synthetic resin pulley T: Ball bearing 1: Outer ring 11: Circumferential groove 2: Inner ring 3: Ball 4: Cage 5: Seal 6: Resin pulley 61: Outer cylindrical portion 610: Outer cylindrical surface 62: Inner cylindrical part 620: inner peripheral surface 621: across the annular projection 622: central annular projection 63: connecting portion 64: both side surfaces 65: escape portion 66: reinforcing rib 67: space portion _{U 1:} upper die _{U 2:} upper core pin portion _L 1: Lower mold L ₂ : Lower core pin part C: Cavity

Claims (2)

Outer ring,
Inner ring,
A plurality of rolling elements interposed between the outer and inner rings;
In a bearing-integrated synthetic resin pulley in which a synthetic resin pulley is fixed to the outer peripheral surface of an outer ring of a rolling bearing consisting of insert molding,
A bearing-integrated synthetic resin pulley, wherein an outer peripheral surface of the synthetic resin pulley is a machined surface.   Further, the synthetic resin pulley has an outer cylindrical portion, an inner cylindrical portion, and a connecting portion that connects the outer cylindrical portion and the inner cylindrical portion, and the outer cylindrical portion is provided on both sides of the connecting portion. The bearing-integrated synthetic resin pulley according to claim 1, wherein a plurality of reinforcing ribs for reinforcing the strength in the radial direction are provided radially at predetermined equal intervals in the circumferential direction.

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