Retainer for ball bearing and ball bearing

Abstract

The present invention relates to a retainer for a ball bearing and a ball bearing capable of preventing interference with balls and an inner peripheral surface of an outer ring even under high-speed rotation conditions and excellent in strength at a fusion portion. The retainer for a ball bearing is a retainer for a ball bearing of a crown shape in which a plurality of pockets (3) opened to one side in the axial direction and spaced apart in the circumferential direction are formed on a retainer main body in a ring shape and balls (B) are held by the pockets, in which retaining claws protruding to one side in the axial direction are formed on both sides in the circumferential direction of each pocket, and column portions having a standing reference surface of the retaining claws are formed between the pockets, the retainer being an injection-molded body of a resin composition, the glass transition temperature being 120°C or higher, and linear fusion lines (2) are formed in regions including a first region (R1) and a second region (R2) formed by the column portions (5) in a circumferential region of the retainer, the first region being a region from a boundary position of the retaining claws and the column portions to an intermediate position of the bottom of the pocket.

Description

Technical Field

[0001] This invention relates to a resin retainer for ball bearings used in various automobiles, industrial machinery, etc., and a ball bearing having the retainer. Background Technology

[0002] A ball bearing arranges balls, which act as rolling elements, in the raceway space between the inner and outer rings, and holds these balls in place by a cage. From the perspective of reducing bearing costs and making the bearing lighter, ball bearings are sometimes made with resin cages, for example, by using resin materials through injection molding.

[0003] For example, as described in Patent Document 1, the retainer used in ball bearings for automotive transmissions is typically a crown-shaped retainer formed of an aliphatic polyamide resin (e.g., polyamide 6 resin, polyamide 66 resin, polyamide 46 resin, etc.) containing 15 to 35% by weight of glass fiber.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 4626183 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, in recent years, the number of electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fuel cell vehicles (FCEVs) with electric motors has been increasing. Due to the miniaturization of motors based on EVs, the motor support and the shaft on the reducer side directly connected to the motor shaft, at maximum speeds, for example, at the dm·n value (the pitch circle diameter dm (mm) of the rolling element and the raceway rotational speed n (min) of the raceway),... -1 This type of bearing is used in areas where the product of the bearing diameter (C / C) is 1.45 million or higher. As a result, under high-speed rotation conditions, due to centrifugal force, the front end of the crown retainer deforms laterally in the outer diameter direction, interfering with the inner circumferential surface of the ball and outer ring, and the bearing sometimes overheats. Moreover, when the temperature of the bearing, which is heated due to high-speed rotation, reaches, for example, above 90°C, in addition to centrifugal force, the deformation of the retainer will be aggravated, which may make the above-mentioned interference more likely.

[0009] Furthermore, it is known that in resin retainers, the weld zone formed during injection molding is typically the weakest point in the retainer's ring strength. Therefore, weld strength that can withstand high-speed rotation is required.

[0010] The present invention was made in view of the following background, and its object is to provide a ball bearing retainer that can prevent interference with the ball and the inner circumferential surface of the outer ring even under high-speed rotation conditions and has excellent strength at the weld joint, and a rolling bearing using the retainer.

[0011] Methods for solving problems

[0012] The ball bearing retainer of the present invention is a ball bearing retainer having a plurality of pockets that open axially to one side and are spaced apart circumferentially on an annular retainer body, and holding a ball in a crown shape by the pockets. The retainer is characterized in that, in the ball bearing retainer, retaining claws protruding axially to one side are formed on both circumferential sides of each pocket, and a pillar portion having a standing reference surface of the retaining claws is formed between the pockets. The retainer is an injection-molded body of a resin composition with a glass transition temperature of 120°C or higher. A straight weld line is formed in a region of the circumferential region of the retainer, including a first region and a second region. The first region is the region from the boundary position between the retaining claw and the pillar portion to the midpoint between the boundary position and the bottom of the pocket, and the second region is the region formed by the pillar portion.

[0013] The feature is that the aforementioned weld line is formed only in the first region of the aforementioned circumferential region. Furthermore, the aforementioned weld line is formed in a region lower than the height position of the center P of the pocket.

[0014] The feature is that a chamfered portion, consisting of an inclined surface, is formed at the inner diameter end of the end face on the opposite axial side of the retainer, and the chamfered angle of the chamfered portion relative to the end face is 20° to 40°. Furthermore, the chamfered angle is smaller than the chamfered angle of the chamfered portion formed at the outer diameter end of the end face.

[0015] The feature is that the difference between the outer diameter length HD (mm) and the inner diameter length Hd (mm) of the retainer is 7.5mm or more, and the chamfered portion is formed within a range of [Hd+3]mm centered on the diameter center of the retainer.

[0016] The feature is that the difference between the outer diameter length HD (mm) and the inner diameter length Hd (mm) of the retainer is less than 7.5mm, and the chamfered portion is formed within a range of [Hd+0.4×(HD-Hd)]mm centered on the diameter center of the retainer.

[0017] The feature is that when the axial wall thickness at the column portion is set as a, the axial wall thickness at the bottom of the pocket is set as b, and the length from the reference surface of the column portion to the part with the fastest rotation speed of the ball is set as c, a>b and c>0 are satisfied.

[0018] The resin composition is characterized in that it contains 15% to 50% by mass of fiber reinforcing material relative to the total resin composition.

[0019] The ball bearing of the present invention comprises an inner ring and an outer ring, a plurality of balls between the inner ring and the outer ring, and a retainer for holding the balls, characterized in that the retainer is a retainer for ball bearings of the present invention.

[0020] The ball bearing is characterized by having a dm·n value of 70×10 4 The bearings used in the above high-speed rotation.

[0021] Invention Effects

[0022] The ball bearing retainer of the present invention is a crown-shaped retainer, which is an injection-molded body of a resin composition with a glass transition temperature of 120°C or higher. A straight weld line is formed in the circumferential region of the retainer, including a first region from the boundary between the retaining claw and the post to the midpoint between the boundary and the bottom of the pocket, and a second region formed by the post. This can suppress the deformation of the retainer caused by centrifugal force under high-speed rotation conditions, prevent interference with the inner circumferential surface of the ball and the outer ring, and since the weld line is formed in a predetermined circumferential region with a relatively thick wall, it becomes a retainer with excellent strength at the weld.

[0023] The ball bearing of the present invention is a rolling bearing comprising an inner ring and an outer ring, a plurality of balls between the inner ring and the outer ring, and a retainer for retaining the balls. The retainer described herein is a retainer for the ball bearing, thus enabling the suppression of deformation caused by heat even under high-speed rotation conditions, even when the dm·n value is 70 × 10⁻⁶. 4 It can also be used appropriately under the above high-speed rotation conditions. Attached Figure Description

[0024] Figure 1 This is a top view showing an example of the retainer for ball bearings according to the present invention.

[0025] Figure 2 This is a diagram used to illustrate the location where the fusion line is formed.

[0026] Figures 3(a) to (b) are diagrams showing the formation pattern of the fusion line.

[0027] Figure 4 yes Figure 1 Axial sectional view of the retainer for a ball bearing.

[0028] Figure 5 yes Figure 1 An enlarged side view of the retainer for a ball bearing.

[0029] Figure 6(a) to (b) are perspective views showing other examples of the ball bearing retainer of the present invention.

[0030] Figure 7 This is a partial cross-sectional view showing an example of the ball bearing of the present invention.

[0031] Explanation of reference numerals in the attached figures

[0032] 1. Cage (cage for ball bearings)

[0033] 2. Holder body

[0034] 2a Bottom surface

[0035] 2b Chamfered section

[0036] 2c Chamfered part

[0037] 3 pockets

[0038] 3a surface

[0039] 3b bottom

[0040] 3C slot

[0041] 4a, 4b Keep the claws

[0042] 5. Column

[0043] 5a Reference Surface

[0044] Roots of 6a and 6b

[0045] 7. Thin-walled section

[0046] 11. Retainer (for ball bearings)

[0047] 12. Cage (cage for ball bearings)

[0048] 21. Bearing (ball bearing)

[0049] 22 Inner Circle

[0050] 23 Outer ring

[0051] 24 balls

[0052] 25. Cage (cage for ball bearings)

[0053] 26 Sealing components

[0054] 27. Lubricating Grease

[0055] α, β chamfer angles

[0056] Hd Inner Diameter Length

[0057] HD outer diameter length

[0058] Hd1 chamfer diameter

[0059] R1 First Area

[0060] R2 Second Region. Detailed Implementation

[0061] based on Figure 1 An example of the ball bearing retainer (hereinafter referred to as "retainer") of the present invention will be described. Figure 1 This is a top view of the retainer. It should be noted that the direction parallel to the diameter center O of the retainer is called the "axial direction", the direction orthogonal to the diameter center O is called the "radial direction", and the direction around the axis centered on the diameter center O is called the "circumferential direction".

[0062] like Figure 1 As shown, the retainer 1 is a crown-shaped retainer that holds a ball, which is a rolling element, at equal intervals in the circumferential direction through pockets 3. The retainer 1 has multiple pockets 3 formed on the annular retainer body 2, opening towards the axial direction to hold the ball. Retaining claws 4a and 4b protruding towards the axial direction are formed on both sides of each pocket 3 in the circumferential direction. Additionally, a post portion 5 is formed between each pocket 3. It should be noted that... Figure 1 In the middle, 11 pockets 3 and 11 pillars 5 are formed, but their number is not particularly limited. As mentioned above, one axial side is the side that holds the claw protrusion, and the opposite side is the other axial side.

[0063] The retainer 1 is an injection-molded body of a resin composition, formed by injecting molten resin into a cavity using a single-point gate or multiple-point gates (e.g., 2 to 6 points). For example, in the case of a single-point gate, a weld line is formed at approximately opposite positions of the gates. Specifically, the weld lines are formed as straight lines at the point where the resin flows from both sides of the retainer 1 in a substantially equal circumferential direction. Furthermore, in the case of multiple-point gates, straight weld lines are formed between adjacent gates in the circumferential direction. It should be noted that the term "straight line" here includes not only strictly straight lines but also straight lines containing curves.

[0064] In the retainer of this invention, the fusion line is formed at a predetermined location. Use Figure 2 The location where the fusion line is formed is described.

[0065] Figure 2 Figure 3 shows a developed view of the periphery of the retainer's pocket, viewed from the outer periphery towards the radially inward side. Figure 5 The same applies. For example... Figure 2As shown, in the retainer 1, opposing retaining claws 4a and 4b are bent towards each other, and a pocket 3 is formed between the retaining claws 4a and 4b. A pillar portion 5 with a standing reference surface 5a of the retaining claws 4a and 4b is formed between the back faces of adjacent retaining claws 4a and 4b at the edges of the adjacent pockets 3. Furthermore, the annular retainer body 2 includes: a pillar portion 5 formed between a pair of retaining claws 4a and 4b and an adjacent pair of retaining claws 4a and 4b; multiple pairs of roots 6a and 6b formed on the axial opposite side of each pair of retaining claws 4a and 4b; and a thin-walled portion 7 formed between each pair of roots 6a and 6b. A pocket 3 for retaining balls is formed between each pair of retaining claws 4a and 4b and the thin-walled portion 7.

[0066] exist Figure 2 In this context, the point on the intersection line of the surface extending circumferentially from the reference surface 5a to each retaining claw side and the pocket surface is taken as the intermediate position q. The region in the circumferential region of the retainer 1 from the boundary position p of the retaining claws 4a, 4b and the post 5 to the intermediate position q is taken as the first region R1. For example... Figure 2 As shown, the boundary position p is the location where the axial distance of the retainer changes abruptly. Furthermore, the region where the pillar 5 is formed, that is, the region from the boundary position p between one retaining claw (e.g., 4b) and the pillar 5 to the boundary position p between the other retaining claw (e.g., 4a) and the pillar 5, is designated as the second region R2.

[0067] In the retainer 1, in region R (including the first region R1 and the second region R2) Figure 2 A weld line is formed in the region (from the middle position q of one side to the middle position q of the other side). Figure 2 In the diagram, for ease of explanation, crossed shading lines are used to indicate areas where weld lines can form. In the retainer 1, in other words, no weld line is formed in a defined area centered on the bottom 3b of the pocket 3 (the portion of the pocket 3 that connects to the shortest axially distanced portion in the thin-walled section 7). When the ball bearing rotates, the stress generated by centrifugal force concentrates at the bottom 3b of the pocket 3 in the retainer 1. Furthermore, as... Figure 2 As shown, the axial wall thickness of the region where the pocket 3 is formed is thinner closer to the bottom 3b of the pocket 3. In this invention, by avoiding a predetermined area including the bottom 3b of the pocket 3, a weld line is formed in a region R with a relatively thick wall, thereby improving the strength at the weld line.

[0068] The weld line is formed as a straight line extending in a direction intersecting the circumference of the retainer 1 (e.g., an orthogonal direction, an inclined direction). The weld line can be visually confirmed. It should be noted that the number of weld lines is determined by the number of gates; there can be one or multiple weld lines.

[0069] Specifically, the formation patterns of the fusion line in the retainer 1 include (1) a pattern formed only in the first region R1, and (2) a pattern formed in both the first region R1 and the second region R2.

[0070] Figure 3(a) shows an example of the forming pattern described in (1) above. In this forming pattern, one or more weld lines are formed only in the first region R1 in the retainer. Weld lines formed only in the first region R1 means that all weld lines w, as confirmed by visual inspection, fall within the first region R1. For example, in Figure 3(a), by forming the weld lines w in a portion having a wall thickness greater than the axial wall thickness of the column portion 5, the strength at the weld lines w can be improved.

[0071] In the pattern shown in Figure 3(a), the weld line is preferably formed in the first region R1, below the height position h of the pocket center P. The height position h is positioned on a straight line passing through the pocket center P and parallel to the bottom surface 2a of the retainer, thus becoming the location where the ball's rotation speed is fastest. As shown in Figure 3(a), although the weld line w is formed in the thicker part, by avoiding placing the weld line in the part where the ball's rotation speed is fastest, the strength at the weld line can be effectively improved. It should be noted that the pocket center P can be calculated as the center position of an imaginary circle drawn based on the diameter of each pocket of the retainer by measuring the shape of the diameter.

[0072] Figure 3(b) shows an example of the formation pattern described in (2) above. In this formation pattern, if there is one weld line in the retainer, as shown in the figure, the weld line w is formed across the first region R1 and the second region R2. Alternatively, if there are multiple weld lines, at least one weld line may be formed only in the first region, and at least one weld line may be formed across the first region R1 and the second region R2. Furthermore, it is preferable that at least one of the two ends of the weld line is not located at the corner R of the retainer. It should be noted that, in the case of this formation pattern, as shown in Figure 3(b), the weld line w is also preferably formed in a region lower than the height position h of the pocket center P.

[0073] then, Figure 4 A cross-sectional view of retainer 1 ( Figure 1 (AA-line sectional view). Figure 4The upper part of the cross-section represents the cross-section at the bottom 3b of the pocket 3, and the lower part represents the cross-section at the column 5. The bottom surface (the end face on the opposite side of the axial direction) 2a of the retainer 1 forms a flat surface orthogonal to the axial direction of the retainer 1, and is formed in an annular shape. A chamfered portion 2b is formed at the inner diameter end of the bottom surface 2a, and a chamfered portion 2c is formed at the outer diameter end. The chamfered portions 2b and 2c are formed throughout the entire circumference of the retainer 1, and are respectively formed in annular shape to form concentric circles. The chamfered portions 2b and 2c can also be formed by inclined planes (e.g., chamfered right angle surfaces) and inclined curved surfaces (e.g., chamfered rounded corner surfaces), respectively. Figure 4 In the middle, the chamfered parts 2b and 2c are formed by inclined planes.

[0074] exist Figure 4 In the case of the chamfered portion 2b on the inner diameter side, the chamfer angle α (the angle of inclination (acute angle) relative to the bottom surface 2a) is not particularly limited, for example, it is 20° to 60°, preferably 20° to 40°. Additionally, as... Figure 4 As shown, the chamfer angle α is preferably smaller than the chamfer angle β (the angle of inclination (acute angle) relative to the bottom surface 2a) of the chamfered portion 2c on the outer diameter side. For example, if the chamfer angle β on the outer diameter side is 45°, the chamfer angle α on the inner diameter side can be set to 20°~40°.

[0075] exist Figure 4 In this case, the chamfer depth of chamfered portion 2b from bottom surface 2a is the same as the chamfer depth of chamfered portion 2c from bottom surface 2a. If we observe the axial wall thickness of the cross-sectional portion at the bottom 3b of the pocket 3, the axial wall thickness of the outer diameter side portion can be ensured compared to the inner diameter side portion, corresponding to the smaller chamfer angle α compared to the chamfer angle β (α < β). This achieves lightweighting of the retainer through chamfering and easily ensures the wall thickness of the outer diameter side portion, which is more susceptible to centrifugal force.

[0076] Furthermore, from the viewpoint of achieving a lightweight retainer 1 and ensuring the axial wall thickness at the pocket 3 of the retainer 1 to suppress deformation of the retainer 1 caused by centrifugal force (e.g., elliptical deformation of the annular portion), it is preferable that the chamfered portion 2b on the inner diameter side is formed within a specified range. Specifically, the relationship between the outer diameter length HD (mm, the same below) and the inner diameter length Hd (mm, the same below) of the retainer 1 is set as follows.

[0077] Preferably, the chamfered portion 2b is formed within a range of [Hd + 0.4 × (HD - Hd)] mm or less centered on the diameter center O of the retainer 1. In other words, it is preferable to have a chamfer diameter Hd1 within the range of [Hd + 0.4 × (HD - Hd)] mm for the chamfered portion 2b. In this case, the chamfer diameter Hd1 can also be set to [Hd + 0.4 × (HD - Hd)] mm. Furthermore, by setting the chamfer angle α to 20° to 40°, it can also be appropriately used during high-speed rotation.

[0078] In addition, such as Figure 4 As shown, in the retainer 1, a weight-reducing portion 2d may also be formed on the bottom surface 2a of the column portion 5. The weight-reducing portion 2d reduces weight by being recessed from the bottom surface 2a towards one side of the axial direction. The weight-reducing portion 2d is not connected to the chamfered portions 2b and 2c, forming a closed recess. The weight-reducing portion 2d is preferably formed within the circumferential region (second region) formed by the column portion 5, but it may also be formed as a groove extending circumferentially. By forming such a weight-reducing portion 2d, the reduction in strength of the retainer 1 can be suppressed, and the retainer 1 can be made lighter.

[0079] Furthermore, from a lightweight perspective, it is preferable to make the axial wall thickness at the column portion 5 of the retainer 1 thinner than that of conventional retainers. For example, such as... Figure 5 As shown, when the axial wall thickness at the column 5 is set as 'a' and the axial wall thickness at the bottom 3b of the pocket 3 is set as 'b', it is preferable to set a > b. For example, a:b is set to approximately 1.5~3.0:1. Furthermore, in Figure 5 In this design, the length from the reference plane 5a of the column 5 to the point where the ball's rotation speed is fastest is defined as c, so that c > 0. This reduces the influence of centrifugal force on deformation, enabling a lightweight retainer that minimizes strength reduction.

[0080] The axial wall thickness 'a' of the column portion 5 (including the chamfered portion in this case) is set, for example, to 1 / 80 to 1 / 20 of the retainer PCD, or it can be set to 1 / 62 to 1 / 26. By setting it within this range, the strength of the column portion 5 can be easily ensured. It should be noted that the retainer PCD refers to an imaginary circle formed by making the centers of each pocket continuous along the circumference (see reference). Figure 1 The pitch circle diameter.

[0081] The axial wall thickness b at the bottom 3b of the pocket 3 (including the chamfered portion in this case) is set, for example, to 1 / 70 to 1 / 30 of the retainer PCD. This ensures the rigidity of this part, effectively preventing deformation even during high-speed rotation, and also prevents interference with the sealing components used to seal the annular space of the bearing.

[0082] Furthermore, grooves 3c and 3c constituting a grease inflow path are formed on the inner surfaces of the retaining claws 4a and 4b in the face 3a of the pocket 3 forming the retainer 1. The bottom surface of these grooves 3c and 3c has an arc-shaped cross-section. The grooves 3c and 3c are arranged on a straight line passing through the center P of the pocket and parallel to the bottom surface 2a of the retainer 1 (the part where the ball rotates the fastest). In this case, the grooves 3c and 3c are formed along the inner surfaces of the retaining claws 4a and 4b from the inner diameter side to the outer diameter side. In this way, by placing the grease inflow path at the part where the ball rotates the fastest, oil film rupture can be effectively prevented, and a longer service life can be achieved. In addition, it is preferable that the weld line is not connected to the grooves 3c and 3c.

[0083] It should be noted that the cross-sectional shape of the bottom surface of grooves 3c and 3c is not limited to... Figure 5 The groove can be an arc shape, such as a triangle or a trapezoid. Alternatively, the groove can be formed not from the inner diameter side to the outer diameter side, but as a groove shape that opens only on one side (e.g., the inner diameter side).

[0084] The resin composition will now be described. The ball bearing retainer of the present invention is composed of a resin composition having a glass transition temperature of 120°C or higher.

[0085] The synthetic resin used as the base resin in the above-mentioned resin composition is an injection-molded resin, and the resin composition only needs to meet the requirement that its glass transition temperature is 120°C or higher. For example, aromatic polyamide resin, polyetheretherketone (PEEK) resin, polyetherketone (PEK) resin, polyamide-imide (PAI) resin, etc. can be used. These synthetic resins can be used alone or as a polymer alloy of two or more.

[0086] Of the above, aromatic polyamide resins are preferred. Aromatic polyamide resins offer superior heat resistance and other properties compared to aliphatic polyamide resins (such as polyamide 66 and polyamide 46). An aromatic polyamide resin refers to a polyamide resin whose molecule contains an aromatic ring; any monomer unit of the aromatic polyamide may contain an aromatic ring. Specifically, the monomer unit may contain a portion derived from at least one of an aromatic diamine, a diamine having an aromatic ring, an aromatic dicarboxylic acid, or a dicarboxylic acid having an aromatic ring. Examples of aromatic diamines include p-phenylenediamine and m-phenylenediamine; examples of diamines having an aromatic ring include m-phenylenediamine and p-phenylenediamine. Similarly, examples of aromatic dicarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid; examples of dicarboxylic acids having an aromatic ring include terephthalic acid.

[0087] In the monomer units of the aforementioned aromatic polyamides, at least one of the diamine and dicarboxylic acid components needs to have an aromatic ring, while the other polymerizing component does not need to have an aromatic ring. For example, aliphatic diamines, alicyclic diamines, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids can be cited as raw materials for components that do not have an aromatic ring.

[0088] Specifically, aromatic polyamide resins can be polyamide 9T, synthesized by polymerizing terephthalic acid (an aromatic dicarboxylic acid) and 1,9-nonanediamine (an aliphatic diamine); polyamide 10T, synthesized by polymerizing terephthalic acid and 1,10-decanediamine; and polyamide 6T, synthesized by polymerizing terephthalic acid and 1,6-hexanediamine. Furthermore, aromatic polyamide resins can also be binary copolymer polyamides or ternary copolymer polyamides, such as polyamide 6T / 6I and polyamide 6T / 6I / 66. Here, " / " indicates a copolymer.

[0089] The weight-average molecular weight of the aromatic polyamide resin is, for example, 15,000 to 50,000. Within this range, flowability during injection molding can be ensured, and deformation of the retainer caused by reduced rigidity can be easily suppressed. The aforementioned weight-average molecular weight is preferably 20,000 to 50,000.

[0090] For example, as the dm·n value increases, the bearing temperature rises due to self-heating caused by sliding. In the case of conventional aliphatic polyamide resins (polyamide 66 resin (glass transition temperature 49°C), polyamide 46 resin (glass transition temperature 78°C)), for example, a decrease in rigidity occurs at 90°C. In contrast, when the glass transition temperature is 120°C or higher as in this invention, there is almost no decrease in rigidity at such temperatures. In addition, creep strain at high temperatures can also be suppressed.

[0091] The upper limit of the glass transition temperature of the resin composition used in the holder of the present invention is, for example, 160°C, or it can be below 150°C. It should be noted that the glass transition temperature of the resin composition can be determined by a differential scanning calorimeter (DSC) based on ISO-11357-1 / -2.

[0092] The above-mentioned resin composition preferably incorporates fiber reinforcement materials such as glass fiber, aramid fiber, carbon fiber, and various mineral fibers (whiskers) within a range that does not hinder injection molding. This improves the rigidity of the retainer and is beneficial for deformation caused by centrifugal force. As a fiber reinforcement material, glass fiber is preferred, especially from the perspective of excellent reinforcement effect and availability. Glass fiber is obtained by spinning inorganic glass with SiO2, B2O3, Al2O3, CaO, MgO, Na2O, K2O, Fe2O3, etc., as its main components. Generally, alkali-free glass (E glass) and alkali-containing glass (C glass, A glass) can be used. Considering the impact on the polyamide resin, alkali-free glass is preferred. Alkali-free glass is borosilicate glass that contains almost no alkali components in the composition. Since almost no alkali components are added, there is almost no effect on the polyamide resin, and the properties of the resin composition do not change.

[0093] The average fiber length of the fiber-reinforced material is not particularly limited, but is preferably 100 μm to 600 μm, and can also be 100 μm to 300 μm. In this specification, the average fiber length is a number-average fiber length, obtained, for example, by randomly selecting a fiber-reinforced material from which the fiber length is to be measured relative to an image obtained through observation under an optical microscope, measuring its long side, and obtaining the measured value. Furthermore, the average fiber diameter of the fiber-reinforced material is, for example, 3 μm to 30 μm, and can also be 4 μm to 18 μm. In this specification, the average fiber diameter is a number-average fiber diameter, measured by means of an electron microscope or atomic force microscope, etc., commonly used in the art.

[0094] When glass fiber is used as the fiber reinforcement material, its proportion relative to the total resin composition is, for example, 15 to 50% by mass. By keeping the glass fiber within this range, molding flowability can be ensured, the rigidity of the retainer can be improved, and the deformation of the retainer can be reduced even under conditions of high temperature and high speed rotation. The above-mentioned proportion relative to the total resin composition is preferably 20 to 40% by mass.

[0095] In the resin composition of this invention, additives other than the aforementioned fiber-reinforcing materials may be added as needed, provided that the retainer function and injection molding properties are not impaired. Other additives may include, for example, solid lubricants, inorganic fillers, antioxidants, antistatic agents, and release agents. Specifically, tetrafluoroethylene resin, graphite, calcium carbonate, clay, talc, silica, wollastonite, and elastomers may also be added.

[0096] The materials constituting the above resin composition are mixed as needed using a Henschel mixer, ball mixer, ribbon mixer, etc., and then melt-blended using a melt extruder such as a twin-screw extruder to obtain molding granules. It should be noted that filler materials can also be added via side feeding during melt blending using a twin-screw extruder, etc. Retainers are then formed using injection molding with these molding granules.

[0097] Molding is performed using a mold. The mold has at least a fixed mold and a movable mold that can be closed and opened relative to the fixed mold. By mating these molds, a molding cavity is formed to create the desired shape of the bearing retainer. One or more gates are provided relative to the molding cavity as resin injection ports, through which molten resin is injected and fills the molding cavity. When the molding cavity is filled with resin, pressure is applied to compress the resin within the molding cavity (pressure holding). After the molten resin has cooled and solidified within the mold for a certain period of time, the mold is opened to obtain the resin bearing retainer.

[0098] In this invention, as described above Figure 2 The weld line is formed in the manner illustrated in Figure 3, and the gate position is set relative to the molding cavity. The gate position is, for example, set to face the portion of the molding cavity corresponding to the outer peripheral surface of the retainer (specifically, region R). In the retainer, a gate mark is formed at the location corresponding to the gate position. For example, the gate mark is formed in region R, or more specifically, it may be formed only in the first region R1.

[0099] The retainer of the present invention is not limited to the structure described above and can be modified in various ways. For example, the number of pockets in the retainer can be varied depending on the number of balls being retained. In addition, the lengths a, b, c, etc., described above can be modified in various ways. Figure 6 A perspective view showing other examples of the retainers of the present invention. These retainers 11 and 12 each have 12 pockets and 12 pillars. The axial wall thickness at the pillars of retainer 11 is thicker than that of retainers 1 and 12, with the length c being c < 0. Furthermore, in retainer 11, grooves for grease inflow are not formed on the surface where the pockets are formed.

[0100] based on Figure 7 An example of the ball bearing of the present invention will be described. Figure 7 This is a partial cross-sectional view of a deep groove ball bearing equipped with the retainer of the present invention, which is used as the ball bearing of the present invention. Figure 7As shown, the bearing 21 has an inner ring 22 with a raceway surface 22a on its outer circumferential surface and an outer ring 23 with a raceway surface 23a on its inner circumferential surface, arranged concentrically. A plurality of balls 24, serving as rolling elements, are sandwiched between the raceway surface 22a of the inner ring and the raceway surface 23a of the outer ring. These balls 24 are held in the pockets of a crown-shaped retainer 25. Furthermore, the bearing 21 includes an annular sealing member 26 provided at the axially open ends of the inner and outer rings, which is lubricated by grease 27 sealed within the bearing internal space formed by the inner ring 22, outer ring 23, retainer 25, and sealing member 26.

[0101] The sealing component 26 is a contact-type sealing component in which the inner diameter lip contacts the sealing groove inside the inner ring 22. The sealing component 26 can be a single metal or rubber molded body, or a composite of a rubber molded body and a metal plate, plastic plate, or ceramic plate. From the perspective of durability and ease of installation, such as... Figure 7 As shown, a composite of a rubber molded body and a metal plate is preferred.

[0102] The ball bearing of the present invention is suitable for use under high-speed rotation conditions. For example, the ball bearing described above has a dm·n value of 70 × 10⁻⁶. 4 Used in the above rotational region. The dm·n value can be 100 × 10⁻⁶. 4 The above can also be 150×10 4 That's all. It should be noted that the upper limit of the dm·n value is, for example, 300 × 10⁻⁶. 4 .

[0103] The bearings of this invention are suitable for electric motors, transmissions, and other applications that operate at high speeds, such as in EVs and HEVs. It should be noted that they can also be used for other purposes, such as supporting machine tool spindles.

[0104] The retainer of the present invention uses a resin composition with a high glass transition temperature, and the weld line is configured in a specified position. Therefore, even if the bearing temperature increases under high-speed rotation conditions, there will be no interference between the inner circumferential surface of the outer ring and the retainer. In addition, it can also improve the rigidity against deformation caused by centrifugal force.

[0105] [Example]

[0106] For cases where the glass transition temperature of the resin composition used in the retainer was changed, the presence or absence of interference between the retainer and the inner circumferential surface of the outer ring under specified operating conditions was analyzed. The resin composition, various conditions, and results are shown in Table 2.

[0107] The operating conditions of the bearings and the shape of the crown retainer (refer to Table 1) are shown below.

[0108] Load: 0~0.10C

[0109] Inner ring speed: 0~dm·n value 1.5 million

[0110] Temperature: Self-heating (no heater required)

[0111] Test duration: 10 hours to 100 hours

[0112] Oil viscosity: VG10~VG32

[0113] Oil supply rate: 10 mL / min ~ 100 mL / min

[0114] [Table 1]

[0115] [Table 2]

[0116] 1) Method based on ISO 11357-1 / -2

[0117] 2) Temperature of the outer diameter of the outer ring during bearing rotation

[0118] 3) 100 × (outer diameter of the retainer after operation - outer diameter of the retainer before operation) / outer diameter of the retainer before operation

[0119] As shown in Table 2, when a resin composition based on existing materials is applied to the retainer (Comparative Examples 1-2), the retainer deforms excessively due to the increase in creep strain, resulting in interference between the retainer and the inner circumferential surface of the outer ring in the range where the dm·n value is 700,000 or higher. On the other hand, when polyamide resin A, a high-Tg material, is applied to the retainer, no interference between the retainer and the outer circumferential surface of the outer ring occurs until the dm·n value reaches 750,000. Furthermore, compared to low-Tg resin compositions, the high-Tg resin compositions also exhibit superior demolding properties and formability. Industrial applicability

[0120] The retainer of this invention can prevent interference with the inner circumferential surface of the ball and outer ring even under high-speed rotation conditions, and has excellent strength at the weld joint. Therefore, it can be widely used as a retainer for ball bearings used in automobiles, industrial machinery, etc. In particular, it can be appropriately used as a bearing retainer for electric motors used under high-speed rotation, such as EVs and HEVs.

Claims

1. A retainer for a ball bearing, comprising an annular retainer body and a plurality of pairs of retaining claws projecting axially from the retainer body, the retainer body comprising a post portion, a thin-walled portion, and a plurality of pairs of root portions, the post portion being formed between a pair of the retaining claws and an adjacent pair of the retaining claws, the plurality of root portions being formed on the other axial side of each pair of the retaining claws, the thin-walled portion being formed between each pair of the root portions, and a pocket for retaining a ball being formed between each pair of the retaining claws and the thin-walled portion, characterized in that, The retainer is an injection-molded part of a resin composition with a glass transition temperature of 120°C or higher. A straight weld line is formed in the circumferential region of the retainer, including a first region and a second region. The first region is the region from the boundary position between the retaining claw and the post to the midpoint between the boundary position and the bottom of the pocket. The second region is the region formed by the post.

2. The retainer for a ball bearing as claimed in claim 1, characterized in that, The fusion line is formed only in the first region of the circumferential region.

3. The retainer for a ball bearing as described in claim 2, characterized in that, The weld line is formed on the opposite side of the axial direction from the center (P) of the pocket.

4. The retainer for a ball bearing as described in claim 1 or 2, characterized in that, At the inner diameter end of the end face on the other side of the axial direction of the retainer, a chamfered portion consisting of an inclined surface is formed. The chamfered angle of the chamfered portion relative to the end face is 20° to 40°, which is smaller than the chamfered angle of the chamfered portion formed at the outer diameter end of the end face.

5. The retainer for a ball bearing as described in claim 4, characterized in that, When the outer diameter of the retainer is set to HD (mm) and the inner diameter is set to Hd (mm), the chamfered portion on the inner diameter side is formed within a range of [Hd+0.4×(HD-Hd)] mm centered on the diameter center of the retainer.

6. The retainer for a ball bearing as described in claim 1 or 2, characterized in that, The resin composition contains 15% to 50% by mass of fiber reinforcement material relative to the total resin composition.

7. A ball bearing comprising: an inner ring and an outer ring, a plurality of balls disposed between the inner ring and the outer ring, and a retainer for holding the balls, characterized in that, The retainer is the retainer for ball bearings as described in claim 1 or 2.

8. The ball bearing as claimed in claim 7, characterized in that, The ball bearing has a dm·n value of 70×10. 4 The bearings used in the above high-speed rotation.

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