JP5428839B2 - Synthetic resin cage, manufacturing method thereof, and rolling bearing - Google Patents

Description

  The present invention relates to a synthetic resin cage for a rolling bearing and a method for manufacturing the same, and more particularly to a technique for preventing a decrease in strength of a weld portion. The present invention also relates to a rolling bearing comprising the synthetic resin cage.

  Bearings for spindle spindles for machine tools are required to have good characteristics such as vibration and sound in order to improve machine accuracy. However, in recent years, high-speed rotation (high rotation speed) is required to further improve machining efficiency. And can be used stably for a long time). Therefore, in order to satisfy such characteristics, a synthetic resin cage that is lightweight and excellent in flexibility is often used.

  This synthetic resin cage is manufactured by an injection molding method. A thermoplastic resin, or a melt of a resin composition in which a reinforcing fiber material is blended with a thermoplastic resin, is injected into a mold from one or more gates. Obtained by cooling and solidifying. However, since the cage for bearings has an annular shape, the melt injected from the gate is diverted in the mold and merges at a certain point (for example, a position facing the gate), so that a weld portion is always generated. Since the melt is merely fused and integrated in the weld portion, the melt is not uniformly mixed, and the strength is lower than other portions. In particular, when a resin composition containing a reinforcing fiber material is used, the reinforcing fiber material is oriented perpendicular to the flow direction in the weld portion, so that the reinforcing effect is not exhibited, and the reinforcing fiber material is used in other parts. Is oriented horizontally with respect to the flow direction, the difference in strength between the weld and other parts becomes larger.

  A flow path is provided on the inner diameter side or outer diameter side of the part corresponding to the pocket of the mold cage so as not to generate a weld part, and the melt flows through the flow path on the opposite side of the gate from the gate to the pocket. It has been proposed to reduce the number of occurrences of welds by smoothly injecting (see Patent Document 1). However, this method also reduces the occurrence of welds, but does not improve the strengthening of the generated welds. Further, it is necessary to scrape the flow path provided in the inner diameter portion or the outer diameter portion of the cage after molding, resulting in an increase in cost due to an increase in manufacturing steps.

  As a method of strengthening the weld portion, after injecting molten resin from the gate provided with the opening / closing valve, the welding portion is moved by operating the opening / closing valve to give a difference in the filling pressure, and thereby the molten resin at the weld portion. Alternatively, it has been proposed to forcibly disturb the flow of the reinforcing material to increase the mixed state of the resin and the reinforcing material (see Patent Document 2). However, this method has a problem that the mold is expensive because the mold structure is complicated.

  Further, as a method for strengthening the weld portion, a resin reservoir is provided in the vicinity of the generation site (weld position) of the weld portion of the mold, and the diameter of the resin reservoir is set so that the injected melt is filled into the cavity and the weld portion is After the formation, the size is determined such that the resin is filled into the resin reservoir, so that the melt flows into the resin reservoir and the pressure balance in the weld portion is lost. It has also been proposed that the material flows and enhances the mixed state of the resin and the reinforcing material (see Patent Documents 3 and 4). However, in this method, since the resin reservoir provided in the mold does not coincide with the weld position, the molten material is not necessarily sufficiently disturbed, and the bearing retainer used under high-speed rotation in recent years. As a result, the reinforcing effect of the weld portion is becoming insufficient.

JP-A-11-108063 JP-A-2-202414 JP-A-2005-321101 Japanese Patent No. 2962926

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a synthetic resin cage in which the strength of the weld portion is higher than that of the conventional one and a rolling bearing having excellent durability.

In order to achieve the above object, the present invention provides a first resin reservoir that leads to an opening provided at a position that coincides with the weld position of the cavity, and is provided in the cavity adjacent to the first resin reservoir. A method of manufacturing a synthetic resin cage for a rolling bearing that uses a cage molding die provided with a second resin reservoir leading to an opening and injection-molds the cage molding resin composition , the cage In the molding die, the distance between the opening of the second resin reservoir and the opening of the first resin reservoir is within the maximum width of the pocket of the cage, and the synthetic resin cage manufacturing process, as well as Bei obtain rolling bearing synthetic resin cage obtained by the method for producing.

According to the present invention, a cage comprising a first resin reservoir provided at a position corresponding to the weld position of the cavity, and a second resin reservoir provided within the maximum width of the cage pocket from the first resin reservoir. A molding die is used. Therefore, the melt injected from the gate into the cavity flows into the first resin reservoir, forcibly flows in the vicinity of the weld, and further flows in the second resin reservoir. Therefore, as compared with the conventional case where a cage molding die having a single resin reservoir that does not match the weld position is used, the enhancement effect at the weld portion is increased, and the durability and reliability are excellent. A synthetic resin cage is obtained. In other words, the thickness of the cage can be reduced, and the weight of the cage and the raw material cost can be reduced. Further, the size of the rolling element can be increased by reducing the wall thickness, the rated load of the bearing can be increased, and the life of the bearing can be extended. Furthermore, the rolling bearing provided with such a synthetic resin cage is also excellent in durability.

It is a perspective view which shows the crown type holder | retainer which is an example of the synthetic resin holders concerning this invention. It is the figure which looked at the 1st example of the cage molding die used by the present invention from the cavity upper part. It is the figure which looked at the 2nd example of the metal mold | die for cage use used by this invention from cavity upper direction. It is the figure which looked at the 3rd example of the metal mold | die for cage use used by this invention from the cavity upper direction. It is the figure which looked at the 4th example of the mold for cage forming used by the present invention from the cavity upper part. It is the figure which looked at the 5th example of the mold for cage formation used by the present invention from the cavity upper part. It is the figure which looked at the 6th example of the mold for cage forming used by the present invention from the cavity upper part. It is the figure which looked at the 7th example of the mold for cage forming used by the present invention from the cavity upper part. It is a perspective view which shows the cage for angular ball bearings which is the other example of the synthetic resin cages concerning this invention. It is a perspective view which shows the other example of the retainer for angular ball bearings which is another example of the synthetic resin cage based on this invention. It is a perspective view which shows the retainer for tapered roller bearings which is another example of the synthetic resin cage based on this invention. It is a perspective view which shows the retainer for cylindrical roller bearings which is another example of the synthetic resin cage based on this invention. It is the top view and side view which show the retainer for needle roller bearings which is the other example of the synthetic resin cages concerning this invention. In Example 5 and Comparative Example 4-6 is a schematic view for explaining a method of measuring the strength of the weld portion inner diameter side. In Example 5 and Comparative Example 4-6 is a schematic view for explaining a method of measuring the strength of the weld outer diameter side.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing a crown-type cage 1 which is an example of a synthetic resin cage according to the present invention, and column portions 11 are erected at equal intervals on one side of an annular base portion 10. A pocket 12 for holding a rolling element (not shown) is formed by a pair of adjacent pillars 11 and 11.

  The cage material includes, for example, polyamide, polyphenylene sulfide resin, polyimide resin, polyether ether ketone resin, or a resin composition in which a fibrous reinforcing material such as glass fiber, carbon fiber, or potassium titanate whisker is blended with these resins. Is used. The content of the fibrous reinforcing material is preferably 40% by mass or less based on the total amount of the resin composition. If the amount is larger than this, the amount of resin is too small and the fluidity at the time of molding is not sufficient, and flows into a resin reservoir described later. It becomes difficult and the effect of suppressing the generation of the weld portion cannot be sufficiently obtained. Moreover, in order to suppress the thermal deterioration at the time of shaping | molding and use, you may add an iodide type | system | group heat stabilizer and an amine heat stabilizer independently, or both. Furthermore, in order to improve impact resistance, rubber-based materials such as ethylene propylene non-diene rubber (EPDM) may be blended.

  The crown type cage 1 is manufactured by injection molding. In the present invention, a mold 100 as shown in FIG. 2 is used. Note that FIG. 2 is a view of the cavity 110 of the cage molding die 100 as viewed from above, and portions corresponding to the column portions 11 and the pockets 12 of the crown type cage 1 are omitted for simplicity. The gate 120 is single.

  In the mold 100, when a melt of a resin composition, which is a cage material, is injected from the gate 120 into the cavity 110, the mold 100 normally flows separately to the left and right to face the gate 120 as illustrated. In the base 10 and the column portion 11 of the retainer 1 obtained by joining at the position, a weld portion is formed at the joining position. Hereinafter, the position where the weld portion occurs is indicated by a virtual line W and is referred to as a weld position W. Therefore, in the present invention, the first resin reservoir 130 is formed through the opening 130a provided at a position corresponding to the weld position W of the cavity 110 of the mold 100, and further, the first resin reservoir 130 is formed in the vicinity of the first resin reservoir 130 through the opening 140a. 2 resin reservoirs 140 are formed. As a result, the melt fills the entire cavity 110 and then flows into the first resin reservoir 130. At this time, the melt flow state is greatly disturbed in the vicinity of the weld position W. Clear boundaries are no longer formed. Moreover, when a fibrous reinforcing material is contained, the fibrous reinforcing material is also randomly oriented. Furthermore, since the melt flows into the second resin reservoir 140 due to the injection pressure or the holding pressure, in addition to the fluidity disturbance due to the first resin reservoir 130, the portion corresponding to the weld portion as a whole is the second resin reservoir 140. It moves to the side of the reservoir 140 and further flow occurs. Thus, the melt flow state is more severely disturbed in the vicinity of the weld position W, and as a result, the strength of the weld portion is further increased.

  In FIG. 2, the first resin reservoir 130 and the second resin reservoir 140 are formed on the outer diameter side of the cavity 110. However, as shown in FIG. 3, the first resin reservoir 130 and the second resin reservoir 140 are formed. 140 may be formed on the inner diameter side of the cavity 110.

  In addition, as shown in FIG. 4, the first resin reservoir 130 can be formed on the outer diameter side of the cavity 110, and the second resin reservoir 140 can be formed on the inner diameter side of the cavity 110. Alternatively, although not shown, the first resin reservoir 130 may be formed on the inner diameter side of the cavity 110 and the second resin reservoir 140 may be formed on the outer diameter side of the cavity 110.

  2 to 4, a plurality of second resin reservoirs 140 may be formed. However, when the second resin reservoir 140 is formed in an even number, for example, the second resin reservoirs 140 and 140 are formed side by side on one side (here, the outer diameter side) of the cavity 110 as shown in FIG. As shown in FIG. 6, it is preferable to form the second resin reservoirs 140, 140 on both sides of the cavity 110 so that the second resin reservoirs 140 are asymmetric about the weld position W. . Further, as shown in FIG. 7, the second resin reservoirs 140 and 140 are formed by changing the separation distance with respect to the first resin reservoir 130, so that the weld position W can be asymmetrical.

  In addition, as shown in FIG. 8, the first resin reservoir 130 and the second resin reservoir 140 may be formed to face each other at the weld position W.

  In the above, each volume of the first resin reservoir 130 and the second resin reservoir 140 is not limited, and the first resin reservoir 130 and the second resin reservoir 140 may have the same volume. The first resin reservoir 130 preferably has a volume corresponding to the amount of resin existing in the region of 0.1 to 10 mm on both sides when the weld position W is an imaginary straight line, while the second resin reservoir 130 The volume of 140 is preferably 30 to 200% with respect to the volume of the first resin reservoir 130. Moreover, when there are a plurality of second resin reservoirs 140, all of them may have the same volume, or may individually differ within the above range.

When the first resin reservoir 130 and the second resin reservoir 140 are opposed to each other as shown in FIG. 8, the volume of each resin reservoir is
(Cavity cross-sectional area at weld position W (mm ² ) / 2) × 0.2 mm × 2
Above, and
(Cavity cross-sectional area at weld position W (mm ² ) / 2) × [circumference of center line of cavity (mm) × (10 ° / 360 °)] × 2
The following is preferable.

  In order to allow the melt to flow into the second resin reservoir 140 after flowing into the first resin reservoir 130, the opening area of the opening 140 a of the second resin reservoir 140 is set to the opening of the first resin reservoir 130. What is necessary is just to make it smaller than the opening area of 130a. Specifically, the opening area of the opening 140 a of the second resin reservoir 140 is preferably 30 to 80% with respect to the opening area of the opening 130 a of the first resin reservoir 130.

  Further, in order to ensure the movement of the melt by the second resin reservoir 140, the opening area of the second opening 140a is the portion of the portion facing the opening 140a (shown by the phantom line A in FIG. 2). It is preferable to make it narrower than the cavity cross-sectional area. Specifically, it is preferably 0.1 to 60% of the cavity cross-sectional area, more preferably 0.1 to 40%.

  When the volume and the opening area in the first resin reservoir 130 and the second resin reservoir 140 are out of the lower limit and the upper limit, the effect of disturbing the flow state of the melt is reduced.

Furthermore, since the opening 140a of the second resin reservoir 140 is preferably closer to the opening 130a of the first resin reservoir 130 , in the present invention, the center of the opening 130a of the first resin reservoir 130 and the second resin reservoir distance between the center of the reservoir 130 of the opening 140a are, we are approaching within the maximum width P of the pocket (2 times the radius of curvature of the snap cage 1 in the pocket 12 of Figure 1).

  In the present invention, as long as the cage molding die 100 including the first resin reservoir 130 and the second resin reservoir 140 is used as described above, molding conditions are not limited, and a conventional synthetic resin cage is used. The molding conditions for injection molding can be used as they are.

  The thus-obtained synthetic resin cage does not have a clear weld, has higher strength, and is superior in durability and reliability. Therefore, it is possible to reduce the wall thickness, reduce the weight of the cage and reduce the raw material cost, and further increase the size of the rolling element by reducing the wall thickness. The rated load increases and the life of the bearing can be extended.

The present invention can be variously modified, and the above is the case of a single gate, but when there are a plurality of gates 120, the first resin reservoir 130 is formed at the weld position W in accordance with the number of gates, The second resin reservoir 140 is formed such that the distance between the center of the opening 130a of the first resin reservoir 130 and the center of the opening 140a of the second resin reservoir 130 is within the maximum width P of the pocket .

  Further, the type of cage is not limited to the crown type cage, but also includes angular ball bearing cages as shown in FIGS. 9 and 10, tapered roller bearing cages as shown in FIG. 11, and as shown in FIG. The present invention can also be applied to the manufacture of cylindrical roller bearing cages and needle roller bearing cages as shown in FIG. 13, and the first resin reservoir and the second resin in the mold cavity corresponding to each cage. What is necessary is just to add a reservoir. In addition, the maximum width P of the pocket which shows the space | interval of a 1st resin reservoir and a 2nd resin reservoir is shown in each drawing.

  The present invention provides a rolling bearing comprising the above synthetic resin cage. Although not shown in any drawings, for example, a ball bearing having a crown-shaped cage as shown in FIG. 1, an angular ball bearing having an angular ball bearing cage as shown in FIGS. 9 and 10, as shown in FIG. Tapered roller bearing with a tapered roller bearing retainer, a cylindrical roller bearing with a cylindrical roller bearing retainer as shown in FIG. 12, and a needle roller bearing with a needle roller bearing retainer as shown in FIG. Etc.

  Examples The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited thereby.

( Reference Example 1)
For ball bearings with an inner diameter of 90 mm and an outer diameter of 115 mm, the mold for the crown type cage with the structure where the pocket and the column face each other (the height of the pocket bottom is 2.2 mm; see Fig. 1) has been improved. Is provided immediately below the center of the pocket, the first resin reservoir is provided at the center position in the width direction of the opposite pillar portion, that is, the weld position, and the second resin reservoir is provided adjacent to the first resin reservoir. It was. Note that the opening of the first resin reservoir was set larger than the opening of the second resin reservoir.

  And the polyamide 66 which contains a glass fiber in the ratio of 25 mass% was made into the molding material, injection molding was performed using the produced metal mold | die, and the crown type holder | retainer was obtained.

( Reference Example 2 )
Injection molding was carried out in the same manner using a mold having the same shape as that of Reference Example 1 and having no first resin reservoir and no second resin reservoir, and a crown type cage was obtained.

( Reference Example 3 )
Injection molding was carried out in the same manner using a mold having the same shape as that of Reference Example 1 and having only the first resin reservoir, and a crown type cage was obtained.

The tensile strength of each crown type cage of Reference Examples 1 to 3 was measured. The results in Table 1 shows a measurement of the crown type cage of Reference Example 2 as a relative value to 1, the injection molding using a mold provided with a second resin reservoir in the vicinity of the first resin reservoir The strength of the crown-shaped cage is remarkably increased as compared with the case of using a mold provided with a single resin reservoir.

(Example 1 )
For ball bearings with an inner diameter of 90 mm and an outer diameter of 115 mm, the mold for the crown type cage (the height of the pocket bottom is 2.2 mm) with a structure in which the pocket and the column face each other has been improved, and the gate of the column is One is provided at the center in the width direction, a first resin reservoir is provided immediately below the center of the opposing pocket (weld position), and a second resin reservoir is provided immediately below one pillar adjacent to the opposing pocket. It was. Further, the opening area of the opening of the second resin reservoir was set to be smaller than the opening area of the opening of the first resin reservoir and thinner than the thickness of the column portion.

  And the polyamide 66 which contains a glass fiber in the ratio of 25 mass% was made into the molding material, injection molding was performed using the produced metal mold | die, and the crown type holder | retainer was obtained.

(Example 2 )
A first resin reservoir and a second resin reservoir are provided in the same manner as in Example 1 , except that a mold with a pocket bottom height of 2.0 mm is used, and the pocket bottom height is 10% (0.2 mm). ), A crown type cage having a weight reduced by 6% was produced.

(Comparative Example 1 )
Injection molding was carried out in the same manner using a mold having the same shape as in Example 1 and having no first resin reservoir and no second resin reservoir, and a crown type cage was obtained.

(Comparative Example 2 )
Injection molding was performed in the same manner using a mold having the same shape as that of Example 1 and having only the first resin reservoir, and a crown type cage was obtained.

The tensile strength of each crown type cage of Examples 1-2 and Comparative Examples 1-2 were measured. The results in Table 2, the injection molding is shown by a relative value to 1 the measured value of the crown type cage of Comparative Example 1, using a second resin reservoir mold provided in addition to the reservoir first resin The strength of the crown-shaped cage is remarkably increased as compared with the case of using a mold provided with a single resin reservoir. In addition, as in Example 2 , sufficient strength is obtained even if the weight (height of the pocket bottom) is reduced.

(Example 3 )
An improved mold for a cage for a tapered roller bearing having an inner diameter of 65 mm and an outer diameter of 90 mm (the height of the large-diameter side annular portion is 2.78 mm; see FIG. 11), and the gate is set to the small-diameter side annular portion. The first resin reservoir was provided at the large-diameter side annular portion (weld position) facing each other, and the second resin reservoir was further provided between the weld position and the nearest column portion. Moreover, the opening area of the opening of the second resin reservoir was set to be smaller than the opening area of the opening of the first resin reservoir and thinner than the wall thickness of the large-diameter side annular portion.

  And the polyamide 66 which contains a glass fiber in the ratio of 25 mass% was made into the molding material, injection molding was performed using the produced metal mold | die, and the cage was obtained.

(Example 4 )
The first resin reservoir and the second resin reservoir are provided in the same manner as in Example 3 , except that a mold with a large-diameter side annular portion height of 2.22 mm is used, and the large-diameter side annular portion height is A cage having a thickness of 20% (0.56 mm) and a weight reduced by 8% was produced.

(Comparative Example 3 )
Using the same shape as in Example 3 and without the first resin reservoir and the second resin reservoir, injection molding was performed in the same manner to obtain a cage.

The tensile strength of each cage of Examples 3 to 4 and Comparative Example 3 was measured. The results are shown in Table 3 as relative values with the measured value of the cage of Comparative Example 3 being 1, but in the same manner as the above crown cage, a second resin reservoir is provided in addition to the first resin reservoir. The strength of the cage injection-molded using the metal mold is remarkably increased as compared with the case of using the metal mold having no resin pool. Further, as in Example 4 , sufficient strength can be obtained even if the weight is reduced. In the tapered roller bearing of Example 4, the roller length can be increased by 0.56 mm compared to the tapered roller bearing of Example 3 , and as a result, the rated load of the bearing can be increased by 4%, and the life can be extended. .

(Example 5 )
A mold for a cylindrical roller bearing retainer (see FIG. 12) having an inner diameter of 65 mm and an outer diameter of 120 mm has been improved, and a gate (reference numeral G) is provided at the center of the inner diameter side of all pockets of one annular portion, while the other A first resin reservoir was provided at the outer diameter side center (weld position) of each pocket of the annular portion, and a second resin reservoir was further provided opposite the weld position. Moreover, the opening area of the opening of the second resin reservoir was set to be smaller than the opening area of the opening of the first resin reservoir.

  And the polyamide 66 which contains a glass fiber in the ratio of 25 mass% was made into the molding material, injection molding was performed using the produced metal mold | die, and the cage was obtained.

(Comparative Example 4 )
Injection molding was performed in the same manner using a mold having the same shape as in Example 5 and having no first resin reservoir and no second resin reservoir to obtain a cage.

(Comparative Example 5 )
Injection molding was performed in the same manner using a mold having the same shape as in Example 5 and having only the first resin reservoir, and a cage was obtained.

(Comparative Example 6 )
Injection molding was performed in the same manner using a mold having the same shape as in Example 5 and having only the second resin reservoir, to obtain a cage.

An arc-shaped test piece was cut out from the annular part on the side including the weld part of each cage of Example 5 and Comparative Examples 4 to 6 , and the strength was measured as shown in FIGS. That is, FIG. 14 shows a method for measuring the strength on the inner diameter side of the weld portion of the test piece. The test piece 100 is arranged on a flat test table 90 so that the outer diameter side 101 is convex, and the test piece is tested. A jig 110 was placed at the center of 100 and a load was applied in the vertical direction via the jig 110. A load cell (not shown) was connected to the jig 110, and the load when the test piece 100 was broken was determined. FIG. 15 shows a method of measuring the strength of the outer diameter side of the welded portion of the test piece. One end of the test piece 100 is cantilevered on the test stand 90, and a vertical direction is passed through the jig 110 near the other end. The load when the test piece 100 was broken by applying a load in the direction was determined. The results are shown in Table 4 as relative values with the measured value of the cage of Comparative Example 4 being 1, but in the same manner as described above, a mold provided with a second resin reservoir in addition to the first resin reservoir was used. The strength of the cage molded by injection molding is remarkably increased as compared with the case of using a mold provided with a single resin reservoir.

DESCRIPTION OF SYMBOLS 1 Crown type holder 10 Base 11 Pillar part 12 Pocket 100 Cage molding die 110 Cavity 120 Gate 130 First resin reservoir 140 Second resin reservoir W Weld position P Maximum width of the hooket

Claims (9)

A holding comprising: a first resin reservoir that leads to an opening provided at a position that coincides with the weld position of the cavity; and a second resin reservoir that communicates with the opening provided in the cavity adjacent to the first resin reservoir. A method for producing a cage made of synthetic resin for a rolling bearing for injection molding a resin composition for cage molding using a mold for mold molding ,
In the cage molding die , the synthetic resin is characterized in that the distance between the opening of the second resin reservoir and the opening of the first resin reservoir is within the maximum width of the pocket of the cage. A method for manufacturing a cage made of steel.   2. The composition according to claim 1, wherein in the cage molding die, both the first resin reservoir and the second resin reservoir are provided on an outer diameter side or an inner diameter side of a cavity. Manufacturing method of resin cage.   2. The cage molding die according to claim 1, wherein one of the first resin reservoir and the second resin reservoir is provided on the outer diameter side of the cavity, and the other is provided on the inner diameter side of the cavity. A method for producing a synthetic resin cage as described in 1.   4. The device according to claim 1, wherein a plurality of the second resin reservoirs are provided asymmetrically around the weld position in the cage molding die. 5. Of manufacturing a synthetic resin cage.   5. The holder mold according to claim 1, wherein an opening area of the opening of the second resin reservoir is smaller than an opening area of the opening of the first resin reservoir. 6. A method for producing a synthetic resin cage as described in 1.   2. The cage molding die according to claim 1, wherein an opening area of the opening of the second resin reservoir is smaller than a cavity cross-sectional area of a portion facing the opening of the second resin reservoir. The manufacturing method of the synthetic resin cage | casing of any one of -5. A holding comprising: a first resin reservoir that leads to an opening provided at a position that coincides with the weld position of the cavity; and a second resin reservoir that communicates with the opening provided in the cavity adjacent to the first resin reservoir. A method for producing a cage made of synthetic resin for a rolling bearing for injection molding a resin composition for cage molding using a mold for mold molding,
In the retainer mold, said first resin reservoir and the second resin reservoir and a method for manufacturing synthetic resin cage you characterized that you have provided facing in the weld portion . 8. The synthetic resin cage according to claim 7 , wherein an opening area of the opening of the second resin reservoir is smaller than an opening area of the opening of the first resin reservoir in the mold for molding the cage. Manufacturing method. A rolling bearing comprising a synthetic resin cage molded by the manufacturing method according to claim 1 .

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