JPS5911770B2 - Tapered roller bearing preload device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a preload device in a bearing device equipped with two sets of tapered roller bearings.

BACKGROUND ART Preload systems for tapered roller bearings in this type of bearing device can be roughly divided into two types: a constant pressure preload system and a fixed position preload system.

The fixed position preload method uses two sets of tapered roller bearings, the inner and outer rings.
It is fixed to the shaft and housing in the axial direction with an appropriate preload applied to the bearing, and has the characteristics of being able to apply a large preload and having high rigidity, so it is suitable for preloading under heavy loads. However, the disadvantage is that large preload fluctuations occur due to differences in thermal expansion due to temperature differences between the housing and the shaft.

On the other hand, in the constant pressure preload method, as shown in Fig. 1, the inner and outer rings Aa and Ab of one tapered roller bearing A are fixed to the shaft C and housing D in the axial direction, and the inner ring Ba of the other tapered roller bearing B, for example, is fixed to the shaft C and the housing D. While fixed immovably in the axial direction on the axis C,
The outer ring Bb is supported by the housing D while allowing sliding in the axial direction, and a thrust load is applied to the outer ring Bb using an elastic body such as a disc spring E whose fixed end is seated on a fixed seating surface Da formed on the housing D. (arrow T) is applied, and preload is applied between the tapered roller bearings A and B by the deflection of this elastic body. Although this method cannot apply a large preload like the above-mentioned fixed position preload, it has the feature that the amount of preload applied to the bearing can be kept almost constant, such as by being able to reduce the preload fluctuation due to the difference in thermal expansion. Therefore, it is generally employed in bearing devices that rotate at high speed, such as bearing devices for spindles of machine tools. As mentioned above, constant pressure preload has little preload fluctuation and can always provide a highly accurate preload amount, but
If the external load (thrust load) in the direction of arrow T acts in excess of the preload amount of spring E, the preload load will be lost on the tapered roller bearing A side, making it impossible to rotate smoothly. The machine cannot increase the preload load too much.

On the other hand, a constant pressure preload type bearing preload device that does not cause preload loss is also disclosed in British Patent No. 511127 (Group XX
X) is known. However, since each pair of left and right bearings is designed to have a sliding clearance from the beginning with respect to the housing that restricts their axial sliding, when each bearing is assembled into a device, Since the bearing positions are not regulated, the proper axial position of each bearing cannot be determined, and the accuracy of the bearing device after the bearings are assembled is low. Purpose This invention is to solve the problem of preload loss when a thrust direction load larger than the preload load (preload amount) is applied to a bearing preload device that adopts the constant pressure preload method as described above, without deteriorating the precision of the bearing device as described above. It is an object of the present invention to provide a tapered roller bearing preload device that can solve the problem.

Embodiment The embodiment shown in FIGS. 2 and 3 will be explained below.
In a bearing device in which two sets of tapered roller bearings 1 and 2 capable of simultaneously applying a radial load and a thrust load are arranged so as to be able to apply mutually opposite thrust loads Tl and T2, each of the bearings 1 and 2 Place the inner rings 1a and 2a in position on the shaft 3, and tighten the nuts 4 and 9 and the shoulder end surface 5 of the shaft 3.
, 6, a sleeve 7, a rotating member 8, or other suitable means to fix the shaft axially immovably.

Each outer ring 1b, 2b of each bearing 1, 2 is supported by allowing axial sliding on the inner diameter of the housing 10, and is further provided with an annular portion 10a protruding from the inner diameter of the housing 10. Fixed seat surfaces 11 and 12 are formed on both sides.

The fixed seat surfaces 11 and 12 may be formed by protruding the annular portion 10a that is integral with the housing 10 as described above, but a separate annular body may be fitted to the inner diameter of the housing 10, and screws or stepped portions may be formed. ,
The shaft 3 may be formed by fixing an annular body immovably in the axial direction within the housing 10 by other appropriate means. Large-diameter coil springs 13' and 14' are arranged concentrically with the outer rings 1b and 2b so as to apply preload to the outer rings 1b and 2b.

The amount of preload is applied by the deflection of the springs 13' and 14'. The wire diameter of the left coil spring 13' is made thicker than the wire diameter of the right coil spring 14'', and its elastic force is set to be considerably stronger than that of the right spring 14', so that the coil of the coil spring 14' is initially Keep the outer ring 2b and fixed seat surface 1 in close contact with each other.
The axial bearing sliding amount regulating gap Δδb between the outer ring 1a and the fixed seating surface 11 is configured such that the total clearance of the coil spring 13' is O. The gap Δδo between each coil is set so that the gap Δδa is obtained.
Establish.

FIG. 3 is a diagram showing the relationship between the amount of deflection δ of the coil springs 13' and 14' (which may be disc springs or other elastic bodies) and the load P, starting from the right in FIG. Even if an external thrust load of T2 is applied, the preload amount p of the bearing 1 does not change.

An external thrust load of T1 acts from the left, and T1>Ta
Then, the total clearance Δδa of the coil spring 13' becomes O, and the bearing 1 is prevented from moving further to the right.

On the other hand, a gap of Δδa is formed in the coil spring 14'1, and the amount of preload on the bearing 2 is slightly reduced, but since the rightward movement of the bearing 1 is prevented, the amount of preload on the bearing 2 is still TbO. It remains. Furthermore, FIG. 4 shows another embodiment, in which each bearing 1,
The outer rings 1b and 2b of the bearing 1 are biased by a plurality of small diameter coil springs 13 and 14 arranged around the shaft 3 to give a predetermined preload, and the bearing between the outer ring 1b of the bearing 1 and the fixed seat surface 11 is The sliding amount regulating gap Δδa is configured to be O from the beginning, and the gap Δδb is created only between the outer ring 2b of the bearing 2 and the fixed seat surface 12.
However, the present invention can also be achieved in this manner.

Of course, assuming Δδb=0, the outer ring 1b of the bearing 1 and the fixed bearing surface 1
It goes without saying that the present invention can be similarly applied even if a gap Δδa is provided only between 1 and 1. Each coil spring 13,1
4 are fitted into the inner diameter of the housing 10 so as to be slidable in the axial direction, and have their end faces supported by annular procks 15 and 16 that abut against the outer rings 1b and 2b, respectively, and the fixed ends of the springs 13 and 14 are respectively The user is seated on the fixed seat surfaces 11 and 12. Each block 15, 16 is connected to the fixed seat surface 11, 12, and each outer ring 1b of each bearing 1, 2 is connected via the block 15, 16.
The gap Δδa or Δδb is formed to restrict the amount of sliding of 2b in the axial direction. Each block 15, 16 is provided with axial holes 17 at several locations around its circumference for supporting the springs 13, 14, respectively, and the holes 17 support the same number of springs 13, 14. When the coil springs are held and operated by the block in this manner, there is an advantage that even small coil springs can be used in a functionally effective and safe manner in the required number.

The relationship between the amount of deflection δ of the coil springs 13 and 14 in FIG. 4 and the load P is shown in FIG.

In FIG. 4, even if an external thrust load of T1 is applied from the left side, the amount of preload on the bearing 2 does not change. When an external thrust load T2 acts from the right side and T2>Tb, the gap Δδb of the coil spring 14 becomes 0, and the bearing 2 is prevented from moving further to the left. On the other hand, although a gap of Δδb is formed on the side of the coil spring 13, a preload amount of TaO still remains in the bearing 1.

In the above embodiments, coil springs 13, 14 or 13', 14' are arranged between the tapered roller bearings 1, 2 to bias the outer rings 1b, 2b.
The outer ring 1b,
2b may be fixed immovably in the axial direction, and the inner rings 1a and 2a may be biased to apply preload.

Effects According to the present invention, two sets of tapered roller bearings capable of simultaneously applying a radial load and a thrust load are arranged between a housing and a shaft so that thrust loads can be applied in opposite directions. In the device, one of the inner and outer rings of each bearing is immovably fixed to the shaft or the housing, and the other is supported by the housing or the shaft while allowing sliding in the axial direction, and each outer ring or inner ring that is allowed to slide At least two elastic bodies are provided that individually bias the outer ring or the inner ring, and one of the elastic bodies that bias each outer ring or inner ring that allows the sliding in the direction of the thrust load is provided. The elastic force of the elastic body that biases is set to be larger than the elastic force of the elastic body that biases the other outer ring or inner ring, and the outer ring or inner ring that is biased by the elastic body that has a large elastic force is set. Since a gap is formed between the fixed end of the elastic body and the fixed seat surface on which the fixed end is seated, which regulates the amount of sliding in the axial direction of each outer ring or inner ring that allows the above-mentioned sliding, in the constant pressure preload method, the external load is Even if the preload exceeds the amount of preload on the elastic body, the gap that restricts the amount of sliding in the axial direction of the bearing prevents the preload from being released.In particular, each pair of left and right bearings is individually Due to the biasing force of the left and right elastic bodies that act to provide the necessary preload, initially only one bearing has an axial sliding clearance compared to the housing side or shaft side that regulates the amount of axial sliding of each bearing. By doing so, when the bearing is assembled into the device, the axial position of the bearing on the side where the sliding gap is not initially formed is determined, and the axial position of the other bearing is also determined based on this. Therefore, the bearing accuracy after bearing assembly is improved.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an example of a conventional device, FIG. 2 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 3 is the relationship between the amount of deflection of the elastic body and the load in the embodiment of FIG. 2. Figure 4 showing
The figure is a longitudinal sectional view of another embodiment, and FIG. 5 is a diagram showing the relationship between the amount of deflection of the elastic body and the load in FIG. 4. 1, 2... Tapered roller bearing, 1a, 2a...
...Inner ring, 1b, 2b... Outer ring, 3...
...Axis, 10...Housing, 11, 12...
...Fixed seat surface, 13, 14, 13', 14'...
...Coil spring, 15, 16...Annular block, ΔδA, ΔδB, Δδo...Gap.

Claims (1)

[Claims] 1. A bearing device in which two sets of tapered roller bearings capable of simultaneously applying a radial load and a thrust load are arranged between a housing and a shaft so that thrust loads can be applied in opposite directions. , one of the inner and outer rings of each bearing is immovably fixed to the shaft or the housing, and the other is supported by the housing or the shaft to allow sliding in the axial direction,
At least two elastic bodies are provided that individually bias each outer ring or inner ring that is allowed to slide, and each elastic body that urges each outer ring or inner ring that is allowed to slide in the direction of the thrust load. The elastic force of the elastic body that biases either the outer ring or the inner ring is set to be larger than the elastic force of the elastic body that biases the other outer ring or inner ring, and the elastic force is set to be large. A gap is formed between the outer ring or inner ring on which the elastic body is biased and the fixed seat surface on which the fixed end of the elastic body is seated, which restricts the amount of axial sliding of each outer ring or inner ring that allows the sliding. Tapered roller bearing preload device. 2 A block that is slidable in the axial direction is interposed between each outer ring or inner ring that allows sliding and each elastic body that biases the outer ring or inner ring, and the end face of the block and the elastic body The tapered roller bearing preload device according to claim 1, wherein the gap is formed between the fixed end and the fixed seat surface on which the fixed end is seated. 3. According to any one of claims 1 to 2, the outer ring of each of the bearings is allowed to slide in the axial direction, and a fixed seating surface is provided on the inner diameter of the housing on which the fixed end of each of the elastic bodies is seated. The tapered roller bearing preload device described. 4. The tapered roller bearing preload device according to any one of claims 1 to 3, wherein each of the elastic bodies is a coil spring or a disc spring.