Ball bearing and grease application method for ball bearing

Abstract

To provide a ball bearing and a grease application method for the ball bearing which can achieve a low torque in rotation without being preceded by run-in operation similarly to an operation after a run-in operation.SOLUTION: A ball bearing comprises: an inner ring 1 and an outer ring 2 either of which is a rotary ring and the other of which is a non-rotary ring; a plurality of balls 3 rollably arranged between the inner ring 1 and the outer ring 2; a retainer 4 having openings at one axial ends of pockets 41 for each holding each of the plurality of balls 3; shield plates 50 for each blocking, at each axial end, a clearance between the inner ring 1 and the outer ring 2; and grease 6 which is filled in a space 8 surrounded by the inner ring 1, the outer ring 2, the balls 3 and the shield plates 50. At initial filling, the grease 6 is in contact with the balls 3, but separated from the retainer 4 at the opening side of the retainer 4 in the space 8.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a ball bearing and a method for applying grease to a ball bearing. [Background technology]

[0002] Conventionally, there have been proposed ball bearings having an inner ring and an outer ring, one of which is a rotating ring and the other of which is a non-rotating ring, and a number of balls arranged freely rolling between the inner ring and the outer ring. One of the conventional ball bearings is a ball bearing that is used with grease sealed in it (a so-called grease-sealed ball bearing), and for example, there is one that has a shield plate that seals the gap between the inner ring and the outer ring at both axial ends.

[0003] Patent document 1 describes a ball bearing in which grease is sealed in the space surrounded by the inner ring, outer ring, balls, and shield plate, and the grease is disposed over the entire circumferential area of ​​the non-rotating ring's peripheral surface (the inner peripheral surface of the groove shoulder of the outer ring). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-129872 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, conventional ball bearings that are initially filled with grease can have a large running torque when directly operated due to the effect of the stirring resistance of the grease, so the running torque is usually reduced by performing a break-in run, etc. On the other hand, there is a demand for ball bearings to reduce the running torque by shortening the break-in run time or even without a break-in run, and there is room for improvement.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a ball bearing that can achieve low torque even without break-in, similar to that after break-in, and a method for applying grease to a ball bearing. [Means for solving the problem]

[0007] Therefore, the above object of the present invention is achieved by the following ball bearing configurations (1) to (5). (1) An inner ring and an outer ring, one of which is a rotating ring and the other is a non-rotating ring; A plurality of balls rollably disposed between the inner ring and the outer ring; a cage having an opening at one axial end of each pocket for holding the plurality of balls; a shield plate that closes a gap between the inner ring and the outer ring at both axial ends; grease sealed in a space surrounded by the inner ring, the outer ring, the balls, and the shield plate; A ball bearing comprising: The grease is the cage is disposed so as to come into contact with the balls, and is disposed on the opening side of the cage on the peripheral surface of a non-rotating ring that constitutes the space, over the entire circumferential direction of the peripheral surface, and is disposed at a distance from the cage; ball bearings. (2) The ball bearing according to (1) above, The retainer is The ball is held in the pocket with a part of the ball exposed to the opening side. ball bearings. (3) A ball bearing according to the above (1) or (2), A raceway is defined between the inner ring and the outer ring, on which the plurality of balls can roll; an open end of the retainer located within the raceway; The grease is located outside the raceway. ball bearings. (4) A ball bearing according to any one of (1) to (3), The grease is disposed at a distance from the rotating wheel. ball bearings. (5) An inner ring and an outer ring, one of which is a rotating ring and the other is a non-rotating ring; A plurality of balls rollably disposed between the inner ring and the outer ring; a cage having an opening at one axial end of each pocket for holding the plurality of balls; a shield plate that closes a gap between the inner ring and the outer ring at both axial ends; grease sealed in a space surrounded by the inner ring, the outer ring, the balls, and the shield plate; A method for applying grease to a ball bearing comprising: a step of applying the grease to the entire circumferential surface of a non-rotating ring that defines the space on the opening side of the cage by bringing the grease into contact with the balls and separating the grease from the cage, A method for applying grease to ball bearings. Effect of the Invention

[0008] According to the configurations (1) and (5) above, for example, in an initial sealed state, the grease is arranged so as to come into contact with the balls, and is arranged over the entire circumferential area on the opening side of the cage on the peripheral surface of the non-rotating ring that constitutes the space, and is arranged at a distance from the cage. As a result, the above configuration allows the balls to roll more smoothly compared to when the grease is not in contact with the balls, and the grease is less likely to be crushed compared to when the grease is not separated from (is in contact with) the cage. This reduces the amount of thickener contained in the grease that enters the raceway defined between the inner ring and the outer ring, suppressing an increase in rotational torque. That is, according to the above configuration, the grease comes into contact with the balls while separating from the cage, thereby discharging the base oil of the grease and enabling the balls to roll smoothly with reduced influence of the thickener. In this manner, according to the above-described configuration, the cause of the increase in rotational torque is eliminated, so that low torque can be achieved without the need for a break-in period, similar to that after the break-in period.

[0009] According to the above configuration (2), the retainer holds the balls in the pocket with a portion of the balls exposed at one axial end, thereby properly maintaining the contact state between the grease and the balls and the separation state between the grease and the retainer.

[0010] According to the above configuration (3), the open end of the cage is located inside the raceway and the grease is located outside the raceway, so that the separation state between the grease and the cage is more appropriately maintained.

[0011] According to the above configuration (4), the grease is positioned away from the rotating ring, and therefore the grease is less likely to be crushed even when the bearing space is narrow, compared to a ball bearing in which a predetermined amount of grease is applied to the surface of the rotating ring as well (not a small amount, but, for example, an amount equivalent to that of the non-rotating ring).

[0012] The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by reading the following description of the embodiment of the present invention (hereinafter, referred to as "embodiment") with reference to the accompanying drawings. [Brief description of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing a ball bearing according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view taken along line AA in FIG. 1. [Diagram 3] FIG. 2 is a cross-sectional view of FIG. [Figure 4] FIG. 3 is a view showing a ball bearing according to a comparative example, which corresponds to FIG. 2. [Diagram 5] 1 is a graph showing the evaluation results, where (a) shows an example and (b) shows a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Embodiment> An embodiment of a ball bearing and a method for applying grease to a ball bearing according to the present invention will be described below with reference to the drawings. This ball bearing is used in, for example, a vacuum pump. The present invention is not limited to the embodiment described below, and suitable modifications and improvements are possible. In addition, the material, shape, size, number, location, etc. of each component in the embodiment described below are not limited as long as they can achieve the present invention.

[0015] Fig. 1 is a cross-sectional view showing a ball bearing according to one embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. Fig. 3 is a cross-sectional view taken along line BB in Fig. 1. This ball bearing is composed of an inner ring 1, an outer ring 2, balls 3, a cage 4, a shield plate 50, and grease 6. In this example, the inner ring 1 is a rotating ring, and the outer ring 2 is a non-rotating ring.

[0016] A raceway 7 for balls 3 is defined between the inner ring 1 and the outer ring 2. Specifically, an inner ring raceway groove 12 constituting the raceway 7 is formed in the axial center (left-right direction in FIG. 1 ) of a groove shoulder outer peripheral surface 11 of the inner ring 1, and an outer ring raceway groove 22 constituting the raceway 7 is formed in the axial center of a groove shoulder inner peripheral surface 21 of the outer ring 2.

[0017] Mounting grooves 23 for a shield plate 50 are formed at both axial ends of the groove shoulder inner circumferential surface 21 of the outer ring 2. The shield plate 50 is made of metal, and the inner circumferential edge of the shield plate 50 forms a proximity portion 501 that is adjacent to the groove shoulder outer circumferential surface 11 of the inner ring 1 with a specified gap. This proximity portion 501 is not bent axially inward. The outer circumferential edge of the shield plate 50 forms a fixing portion 52 that is fixed to the mounting groove 23 formed in the groove shoulder inner circumferential surface 21 of the outer ring 2.

[0018] The cage 4 is a crown-shaped cage made of synthetic resin, and has a pocket 41 that is open on one axial side (the right side in FIG. 1). The cage 4 is formed so that the balls 3 can be held in the pocket 41 with a portion of the balls 3 exposed on the opening side. In other words, the depth of the pocket 41 is smaller than the diameter of the balls 3. The cage 4 is also formed so that an open end 42 (so-called claw portion, etc.) is located inside the raceway 7.

[0019] 1, grease 6 is applied (sealed) to the groove shoulder inner peripheral surface 21 of the outer ring 2 so as to come into slight contact with the balls 3 on the opening side of the cage 4 in the space 8 (bearing space) surrounded by the inner ring 1, outer ring 2, balls 3, and shield plate 50. Note that grease 6 is not applied to the space on the opposite side to the opening of the cage 4.

[0020] 2, the grease 6 is applied (enclosed) to the groove shoulder inner peripheral surface 21 of the outer ring 2 so as to be located outside the raceway 7, and is not in contact with the cage 4 (specifically, the opening end 42). Note that the grease 6 is not applied to the cage 4 (specifically, the opening end 42).

[0021] 3, the grease 6 is applied (filled) over the entire circumferential area of ​​the groove shoulder inner circumferential surface 21 of the outer ring 2. More specifically, the grease 6 is configured by a plurality of spherical grease particles 6a arranged without gaps over the entire circumferential area of ​​the groove shoulder inner circumferential surface 21 of the outer ring 2. It is to be noted that the grease 6 is not applied to the groove shoulder outer circumferential surface 11 of the inner ring 1.

[0022] The application (filling) of the grease 6 is performed before the shield plate 50 is attached, from the opening side of the cage 4 using, for example, a nozzle with multiple holes, so that multiple spherical grease particles 6a are placed without gaps all over the circumferential direction of the groove shoulder inner circumferential surface 21 of the outer ring 2. With this method, a conventional grease filling device can be used, so no new equipment is required and no increase in production costs occurs.

[0023] According to this embodiment, by arranging the grease 6 so that it comes into contact with the balls 3 when initially filled, the base oil in the grease adheres to the balls, so that the balls 3 roll more smoothly than when the grease 6 is not in contact with the balls 3. Furthermore, by arranging the grease 6 so as to be spaced apart from the cage 4 when initially filled, the grease 6 is less likely to be crushed than when the grease 6 is not spaced apart from (in contact with) the cage 4. This reduces the amount of thickener contained in the grease 6 that enters the raceway 7, suppressing an increase in rotational torque. In other words, as the grease 6 comes into contact with the balls 3 while separating from the cage 4, the base oil of the grease 6 is discharged, allowing the balls 3 to roll smoothly with reduced effects of the thickener. In this manner, according to this embodiment, the cause of the increase in rotational torque is eliminated, so that low torque can be achieved without the break-in period, similar to that after the break-in period.

[0024] Furthermore, according to this embodiment, the retainer 4 holds the balls 3 in the pocket 41 with a portion of the balls 3 exposed to the opening side (right side in Figure 2), thereby properly maintaining the contact state between the grease 6 and the balls 3 and the separation state between the grease 6 and the retainer 4.

[0025] Furthermore, according to this embodiment, the open end 42 of the retainer 4 is located inside the raceway 7 and the grease 6 is located outside the raceway 7, so that the separation state between the grease 6 and the retainer 4 is maintained more appropriately.

[0026] Furthermore, according to this embodiment, since the grease 6 is positioned away from the inner ring 1, which is the rotating ring, the grease 6 is less likely to be crushed even when the bearing space (space 8) is narrow, compared to a ball bearing in which a predetermined amount of grease 6 is applied to the surface of the rotating ring as well (not a small amount, but, for example, an amount approximately the same as that of the non-rotating ring).

[0027] <Test> In order to evaluate the rotational torque before break-in in the examples and comparative examples, a preload of 2.4 kgf was applied to each ball bearing in the examples and comparative examples in an environment of room temperature of 20°C, and the bearings were subjected to a test for 100 min. -1 , 500min-1 , and 3000 min -1 The rotational torque was measured at each rotation speed. In the embodiment, the ball bearing shown in Figs. 1 to 3 was used. In the comparative example, the ball bearing used was as shown in FIG. 4, in which the open end of the cage protrudes toward the shield plate beyond the axial end of the balls and grease comes into contact with this open end of the cage.

[0028] The evaluation results of the examples and comparative examples are shown in FIG. Low rotation speed 100min -1 and 500 min -1 Although there is no clear difference between the examples and the comparative examples, -1 In this case, the dynamic friction torque value is smaller in the embodiment. The rotational torque is determined by the sum of the load term (magnitude of load: Ml) and the speed term (magnitude of rotational speed: Mv). Here, if the coefficient determined by the bearing type and lubrication method is f0, the dynamic viscosity of the oil is v0, and the rotational speed is n, then the speed term (Mv) can be calculated as f0(v0·n)^(2 / 3)·dm^3. Based on this, if the rotational speed is in the low speed range of 100 min -1 and 500 min -1 The effect is less noticeable at 3000 min. -1 In this case, the rotation speed is constant (for example, 1000 min -1 ) above, it is considered that the difference between the examples and the comparative examples became clear. [Explanation of symbols]

[0029] 1. Inner Circle 2 Outer ring 3 balls 4 Cage 6 Grease 7 orbit 8 Space 11 Groove shoulder outer circumference 12 Inner ring raceway groove 21 Groove shoulder inner circumferential surface 22 Outer ring raceway groove 23 Mounting groove 41 Pocket 42 Open end 50 Shield plate 52 Fixed part 501 Nearby area

Claims

1. An inner ring and an outer ring, one of which is a rotating ring and the other is a non-rotating ring; A plurality of balls rollably disposed between the inner ring and the outer ring; a cage having an opening at one axial end of each pocket for holding the plurality of balls; a shield plate that closes a gap between the inner ring and the outer ring at both axial ends; grease sealed in a space surrounded by the inner ring, the outer ring, the balls, and the shield plate; A ball bearing comprising: The grease is the cage is disposed so as to come into contact with the balls, and is disposed on the opening side of the cage on the peripheral surface of a non-rotating ring that constitutes the space over the entire circumferential direction of the peripheral surface, and is disposed at a distance from the cage; ball bearings.

2. 2. A ball bearing according to claim 1, The retainer is The ball is held in the pocket with a part of the ball exposed to the opening side. ball bearings.

3. 2. A ball bearing according to claim 1, A raceway is defined between the inner ring and the outer ring, on which the plurality of balls can roll; an open end of the retainer located within the raceway; The grease is located outside the raceway. ball bearings.

4. 2. A ball bearing according to claim 1, The grease is disposed at a distance from the rotating wheel. ball bearings.

5. An inner ring and an outer ring, one of which is a rotating ring and the other is a non-rotating ring; A plurality of balls rollably disposed between the inner ring and the outer ring; a cage having an opening at one axial end of each pocket for holding the plurality of balls; a shield plate that closes a gap between the inner ring and the outer ring at both axial ends; grease sealed in a space surrounded by the inner ring, the outer ring, the balls, and the shield plate; A method for applying grease to a ball bearing comprising: a step of applying the grease to the entire circumferential surface of a non-rotating ring that defines the space on the opening side of the cage by bringing the grease into contact with the balls and separating the grease from the cage, A method for applying grease to ball bearings.

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