JPH04357323A - Holder for anti-friction bearing - Google Patents

Abstract

PURPOSE:To relax stress concentration to corners of pockets, and improve the mechanical characteristic of a holder for anti-friction bearing made of the material including nylon and reinforced fiber by forming corners of pockets for holding a rotating member into a shape turned by jointing curved surface. CONSTITUTION:In a holder 1 for anti-friction bearing made of a material including nylon 46 as a resin component and reinforced fiber at 20-40weight%, multiple rectangular pockets 11... having a thickness smaller than the diameter of a needle roll to be held are turned by passing through at equal intervals. In this case, all corners 11a of each pocket 11 are formed into a shape formed by jointing the curved surface R (radius at about 0.3-0.5mm). As reinforcing fibers, glass fibers each having a diameter at 8-12mum are preferably used. Furthermore, it is desirable to include iron oxide fine powder, in which occupancy ratio of the particles having a diameter of 1mum or less is 85% or more, as inorganic filling material. Mechanical characteristic of the bolder for anti-friction bearing is thereby improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cage for rolling bearings.

0002

[Prior Art and Problems to be Solved by the Invention] Conventionally, as the above-mentioned cages, those made of nylon 66, which are lighter than those made of metal and have excellent mechanical properties, have been frequently used. However, the above-mentioned nylon 66 has insufficient resistance (oil resistance) when used in high-temperature lubricating oil, especially in rolling bearings of automobile transmissions.

[0003] The use of nylon 46, which has better oil resistance than nylon 66, has been considered, but this nylon 46 causes orientation problems in injection molded products depending on the molding conditions and mold shape, resulting in poor tensile strength, etc. There was a problem in that the mechanical properties of the steel tend to deteriorate. For example, in the case of the needle roller bearing retainer 9 shown in FIG.
There was a problem in that it was easy to break from the corners 91a, 91a... of 91....

[0004] Therefore, the present inventors investigated various additives and found that by incorporating an elastomer such as ethylene propylene rubber, it was possible to prevent the deterioration of mechanical properties, and filed the previous application ( JP-A-2-13441
(See Publication No. 3). However, when an elastomer is blended, there is a problem in that heat resistance is slightly lowered. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cage for rolling bearings that is excellent in oil resistance, heat resistance, and mechanical properties.

[0005]

[Means and effects for solving the problems] To solve the above problems, the rolling bearing cage of the present invention contains nylon 46 as a resin component and 20 to 40% by weight of reinforcing fibers. This rolling bearing cage is characterized in that the corners of the pockets for holding rolling elements are connected by curved surfaces.

Glass fibers having a diameter of 8 to 12 μm are preferably used as the reinforcing fibers. Further, as the inorganic filler used in the above-mentioned rolling bearing cage, it is preferable to use iron oxide fine powder in which the proportion of particles with a particle size of 1 μm or less is 85% or more. In the rolling bearing retainer of the present invention having the above configuration, the corners of the pockets where stress tends to concentrate are connected and reinforced by curved surfaces, and the stress concentration in these parts is alleviated. Mechanical properties can be improved without adding an elastomer.

FIG. 1 shows a cage 1 for a needle roller bearing as an example of the cage of the present invention. The cage 1 is made of a cylindrical body whose wall thickness is thinner than the diameter of the needle rollers to be held, and around the cylindrical body, there are a plurality of rectangular pockets 11, 11, etc. into which the needle rollers are inserted and held. Penetrations are formed at intervals. Then, the corners 11a, 1 of each pocket 11, 11...
1a... are connected by curved surfaces R, R... The radius of each curved surface R is not particularly limited, but is preferably within the range of 0.3 to 0.5 mm. If the radius of the curved surface R is less than 0.3 mm, the effect of providing the curved surface R is insufficient, and there is a risk that breakage will occur easily from the corner. Conversely, if the radius of the curved surface R exceeds 0.5 mm, the roller There is a risk of clogging.

As mentioned above, the resin component constituting the cage 1 is nylon 46, that is, 1,4-
A compound represented by the following general formula (I), which is a reaction product of diaminobutane and adipic acid, is used.

[0009]

[Chemical formula 1]

As mentioned above, nylon 46 has better oil resistance than nylon 66, and according to studies by the inventors, the strength increases when the corners 11a of the pockets 11 are connected by the curved surface R. It was found to be superior to nylon 66. As the reinforcing fibers contained in the cage 1 together with the nylon 46, glass fibers having a diameter of 8 to 12 μm are preferably used.

[0011] When the diameter of the glass fiber is less than 8 μm, the number of glass fibers per unit weight increases, and nylon 4
6 increases, the initial reinforcing effect increases. However, when used in high-temperature lubricating oil, the oil penetrates the interface between the nylon 46 and glass fiber, and when the bond between the two is peeled off, the peeled area is large, so there is a risk of a significant decrease in strength. be.

On the other hand, when the diameter of the glass fiber exceeds 12 μm, the number of glass fibers per unit weight decreases, and the adhesion area with nylon 46 decreases, so the effect of peeling due to oil penetration decreases; There is a possibility that the initial reinforcing effect will be insufficient. The length of the glass fiber is not particularly limited, and may be the same length as the conventional one (about 200 to 300 μm).

In addition to the above glass fibers, reinforcing fibers that can be used in the present invention include carbon fibers, fibrous wollastonite, silicon carbide fibers, boron fibers, alumina fibers, and Si-Ti-C-O. Fibers, metal fibers (copper, steel,
(stainless steel, etc.), aromatic polyamide (aramid) fibers, potassium titanate whiskers, graphite whiskers, silicon carbide whiskers, silicon nitride whiskers, alumina whiskers, etc.

[0014] The proportion of reinforcing fibers in all components is 20
-40% by weight. When the proportion of reinforcing fibers is less than 20% by weight, the effect of adding the reinforcing fibers cannot be obtained, the toughness deteriorates, and the heat distortion temperature decreases. On the other hand, if the proportion of reinforcing fibers exceeds 40% by weight, the flexibility decreases, especially in the case of an undercut shape, for example, when the molded product is removed from the mold or the rolling elements are press-fitted into the pocket. When this occurs, cracks or cracks occur in the undercut portion.

The cage for rolling bearings of the present invention may contain, in addition to the above-mentioned nylon 46 and reinforcing fibers, inorganic fillers as colorants and various additives (thermal stabilizers, etc.). Various conventionally known inorganic fillers can be used, but iron oxide fine powder in which 85% or more of particles with a particle size of 1 μm or less is particularly preferably used. The iron oxide fine powder mentioned above has a large number of particles per unit weight and the adhesion area with nylon 46 increases, so it has a stronger initial reinforcing effect than inorganic fillers such as iron oxide powder with a larger particle size. increases. Moreover, there is also the effect of improving oil resistance compared to the case where the iron oxide fine powder is not blended.

The above-mentioned inorganic fillers and additives can be contained in the same proportions as conventional ones. The cage of the present invention is
The above ingredients are melted and kneaded to form pellets, powders, etc.
After it is shaped into a shape that can be used as a molding material, it is manufactured by molding using an injection molding machine or the like in the same manner as in the past. The structure of the present invention is applicable not only to needle roller bearings shown in the figure, but also to
It can be suitably applied to cages of all shapes for various rolling bearings such as cylindrical roller bearings and tapered roller bearings.

[0017]

【Example】

<Study of the influence of pocket corner shape> Using the molding materials of compounding examples 1 and 2 shown in Table 1, a needle roller bearing retainer (external A needle roller bearing with a diameter of 57 mm, an inner diameter of 50 mm, a width of 34 mm, pocket dimensions of 3.3 x 26 mm, and a radius of curved surface at the corner of 0.4 mm) and a shape with no curved surface at the corner of the pocket as shown in Fig. 3. (same dimensions except for the shape of the corners).

Next, samples S were prepared by cutting the obtained cage by two pockets, and as shown in FIGS.
, 91) with the protrusions 21, 21 of the pair of jigs 2, 2 inserted, and the breaking strength (kgf) was measured when the jigs 2, 2 were pulled up and down as shown by the arrows in the figure. did. The results are shown in Table 1.

[0019]

[Table 1]

*1: A diameter of 10 μm was used. *2: Strength increase rate (%) was determined by the following formula.

[0021]

[Math 1]

From the results shown in Table 1 above, it was found that nylon 46 had a higher rate of increase in strength than nylon 66 when a curved surface was provided at the corner of the pocket. <Study of influence of glass fiber diameter> As a resin component, 7
0% by weight of nylon 46 and 30% by weight of glass fibers having the diameters shown in Table 2 were blended to produce molding materials of Compounding Examples 3 to 5, and using the molding materials of Compounding Examples 3 to 5, The following tests were conducted.

Tensile Test I ASTM D 638-82a “Standard
Test Method for TENSILE P
The tensile strength at break (kgf/cm2) and tensile elongation at break (%) of the molding materials of each of the above formulation examples were measured in accordance with ``ROPERTIES OF PLASTICS''. Note that, for the measurement, Type I test pieces prepared from the molding materials of each blending example were used.

Tensile Test II The above test pieces were immersed in gear oil at 135°C, and the tensile strength at break (kgf/cm2) was measured after 100 hours, 210 hours, 380 hours, 500 hours, and 1000 hours.
) and tensile elongation at break (%) were measured in the same manner as in Tensile Test I above. Bending test ASTM D 790-81 “Standard
Test Method for FLEXURAL
PROPERTIES OF UNREINFORCE
D AND REINFORCED PLASTICS
AND ELECTRICAL INSULATIN
The bending strength (kgf/cm
2) was measured. In addition, for the measurement, 5 inch length x 1/2 inch width x 1/2 inch width fabricated from the molding material of each formulation example.
A test piece with a height of 1/4 inch was used.

[0025] Also, the above ASTM D 790-1
According to the formula described in Section 1.11, the flexural modulus (kgf/c
m2) was calculated. Izod impact test ASTM D 256-81 “Standard
Test Method for IMPACT RE
SITANCEOF PLASTICS AND EL
ECTRICAL INSULATION MATER
The Izod impact strength (kgf·cm/cm) of the molding materials of each of the above formulation examples was measured in accordance with ``IALS (Test Method for Impact Resistance Properties of Plastics and Electrical Insulators)''. In addition, for the measurement, the molding material made from the molding material of each formulation example,
A test piece with a 1/8 inch notch was used.

The results of the tensile test I, bending test and Izod impact test are shown in Table 2, and the results of the tensile test II are shown in Table 3.
Each is shown below.

[0027]

[Table 2]

[0028]

[Table 3]

*3: The retention rate is based on the data of tensile test I.
The percentage is shown when it is set to 00. From the results in Tables 2 and 3 above, all of Formulation Examples 3 to 5 are excellent in both oil resistance and mechanical properties, but Formulation Example 4 in which the glass fiber diameter is 10 μm is particularly excellent in oil resistance. It turned out that <Examination of the influence of the presence or absence of iron oxide blending and the particle size of iron oxide> Nylon 46 as a resin component, glass fiber with a diameter of 13 μm, and iron oxide fine powder with different particle size distributions were blended in the proportions shown in Table 4. to produce molding materials of Formulation Examples 6 to 8,
The above-mentioned tests were conducted using the molding materials of Blend Examples 6 to 8.

The results of the tensile test I, bending test and Izod impact test are shown in Table 4, and the results of the tensile test II are shown in Table 5.
Each is shown below.

[0031]

[Table 4]

*4: Iron oxide fine powder in which 50% of the particles have a particle size of 1 μm or less. *5: Fine iron oxide powder in which 85% of the particles are particles with a particle size of 1 μm or less.

[0033]

[Table 5]

*6: The retention rate is based on the data of tensile test I.
The percentage is shown when it is set to 00. From the results in Tables 4 and 5 above, Blend Examples 6 to 8 are all excellent in both oil resistance and mechanical properties, but in particular, iron oxide fine powder with a ratio of 85% of particles with a particle size of 1 μm or less Formulation example 8 containing
It was found that it has superior oil resistance compared to <Study of the influence of the presence or absence of elastomer compounding> Nylon 46 as a resin component, glass fibers with the diameter shown in Table 6, and iron oxide fine powder in which particles with a particle size of 1 μm or less account for 85% (Formulation Example 12 only) and ethylene-propylene rubber as an elastomer to produce molding materials of Compounding Examples 9 to 12. Using the molding materials of Compounding Examples 9 to 12, the above-mentioned tests and the following thermal deformation tests were carried out. Temperature measurements were taken.

Heat distortion temperature measurement ASTM D 648-82 “Standard
Test Method for DEFLECTIO
N TEMPERATURE OF PLASTICS
The heat distortion temperature (° C.) of the molding materials of each of the above formulation examples was measured in accordance with ``UNDER FLEXURAL LOAD (Plastic Load Deflection Temperature Test Method)'' by applying a stress of 4.6 kgf/cm to the test piece. In addition,
For the measurement, a length of 5i made from the molding material of each formulation example was used.
A test piece of 1/4 inch in width x 1/2 inch in height was used.

The results of the tensile test I, bending test, Izod impact test, and heat distortion temperature measurement are shown in Table 6 together with the results of the above formulation examples 4 and 8 for comparison, and the results of the tensile test II are also shown in the above table. The results are shown in Tables 7 and 8 together with the results of Formulation Examples 4 and 8, respectively.

[0037]

[Table 6]

[0038]

[Table 7]

*7: The retention rate is based on the data of tensile test I.
The percentage is shown when it is set to 00.

[0040]

[Table 8]

*8: Retention rate is based on the data of tensile test I
The percentage is shown when it is set to 00. From the results in Tables 6 to 8 above, the oil resistance, heat resistance, and mechanical properties of the products containing elastomers were almost the same as those without elastomers, but the heat distortion temperature, which indicates heat resistance, was in,
It was found that it is better not to include an elastomer. <Examples 1 to 9> A needle roller bearing cage (outer diameter 57 mm, inner diameter 50
mm, width 34mm, pocket dimensions 3.3 x 26mm
m, corner curve radius 0.4 mm). <Comparative Example 1> Using a molding material having the same material composition as in Example 6, a cage for a needle roller bearing having a shape without curved surfaces at the corners of the pocket (other than the shape of the corners) as shown in FIG. (same size) was molded.

[0042] The cage strength of each of the above-mentioned Examples and Comparative Examples was measured as follows. Measurement of Cage Strength Samples S were created by cutting the obtained cage by two pockets, and as shown in FIGS. 2(a) and (b), pockets 11, 11 (91, 91) of each sample S With the protrusions 21, 21 of the pair of jigs 2, 2 inserted into the jig 2,
, 2 was pulled up and down as shown by the arrows in the figure, and the breaking strength (initial value, kgf) was measured.

Next, the above sample S was immersed in gear oil at 135°C, and the breaking strength after 1000 hours (after oil resistance, k
gf) was measured in the same manner as above. Then, the retention rate (%) of the breaking strength was determined from the data of the above-mentioned both breaking strengths based on the following formula.

[0044]

[Math 2]

The above results are shown in Tables 9 and 10. In addition, regarding the molding materials used in each of the above examples and comparative examples,
The results of the tensile test I, bending test and Izod impact test are also shown in Tables 9 and 10.

[0046]

[Table 9]

*9: Fine iron oxide powder in which 50% of the particles have a particle size of 1 μm or less. *10: Fine iron oxide powder in which 85% of the particles are particles with a particle size of 1 μm or less.

[0048]

[Table 10]

*11: Fine iron oxide powder in which 50% of the particles have a particle size of 1 μm or less. *12: Fine iron oxide powder in which 85% of the particles are particles with a particle size of 1 μm or less. From the results in Tables 9 and 10 above, it was found that the cage of Comparative Example 1 had insufficient initial cage strength. On the other hand, it was found that the cages of Examples 1 to 9 all had high initial cage strength and were also excellent in oil resistance, heat resistance, and mechanical properties.

[0050]

[Effects of the Invention] Since the rolling bearing cage of the present invention is constructed as described above, the corners of the pockets where stress tends to concentrate are connected and reinforced by curved surfaces, and the corners of the pockets where stress tends to concentrate are connected and reinforced. Since stress concentration is relaxed, mechanical properties can be improved without adding an elastomer. Therefore, the rolling bearing cage of the present invention has excellent oil resistance, heat resistance, and mechanical properties.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a needle roller bearing cage as an embodiment of the rolling bearing cage of the present invention.

FIGS. 2(a) and 2(b) are explanatory diagrams showing a method for measuring the strength of a cage for a needle roller bearing.

FIG. 3 is a perspective view showing a needle roller bearing cage as an example of a conventional rolling bearing cage.

[Explanation of symbols]

1 Cage 11 Pocket 11a Corner R Curved surface

Claims (3)

[Claims] Claim 1: Nylon 46 as a resin component;
A cage for a rolling bearing comprising 40% by weight of reinforcing fiber, characterized in that corners of pockets for holding rolling elements are connected by curved surfaces. 2. A cage for a rolling bearing according to claim 1, wherein the reinforcing fibers are glass fibers having a diameter of 8 to 12 μm. Claim 3: The proportion of particles with a particle size of 1 μm or less is 85
% or more of iron oxide fine powder as an inorganic filler.