JPH0781586B2 - Oil film bearing with hydrostatic effect - Google Patents

Description

TECHNICAL FIELD The present invention relates to an oil film bearing that supports rolls and the like of a rolling mill.

[Conventional technology]

FIG. 7 shows a conventional bearing structure. 8 is a sectional view taken along the line VIII-VIII in FIG. In FIG. 7 and FIG. 8, the rolling load acting on the roll body 1 is transmitted from the roll shaft 2 through the sleeve 2a, the oil film 3 to the shell 4 and the bearing box 5, and is composed of a liner, a load cell, a thrust washer and the like. Is transmitted to the bearing box support portion 6. Here, the oil film 3 is produced by the dynamic pressure effect and the static pressure effect, and the dynamic pressure effect is generated by the inner surface 20 of the roll shaft 2 and the shell 4.
To the oil pocket 7 in the bearing gap formed between
This is a fluid force generated when the lubricating oil supplied at a low pressure of around 1.0 kgf / cm ² is drawn in by the rotation of the roll shaft 2.

On the other hand, the static pressure effect is obtained by a static pressure recess 10 provided at a position facing the inner surface 20 of the shell 4 in a position opposed to the rolling load application direction, from a lubrication line 12 different from the lubrication oil lubrication line 11 that supplies the oil pocket 7. By supplying high-pressure lubricating oil, the entire bearing area (load zone) surrounded by the left and right oil pocket forming ends 8 and 9 and the end faces 13 and 14 in the longitudinal direction of the bearing where the bearing gap expands rapidly. Moreover, a static pressure is applied, and the roll shaft 2 is levitated by the resultant force.

FIG. 9 qualitatively shows the relationship between the minimum oil film thickness and the rotation speed of the roll shaft 2 under a constant load condition. With a bearing having no static pressure effect, the required minimum oil film thickness can be secured in the low speed range. There is a possibility of seizure. However, in the bearing having the static pressure effect, the required minimum oil film thickness can be secured even if the rotation speed is zero. Here, the minimum required oil film thickness is the size of foreign matter in the lubricating oil that enters through the lubricating oil filter installed in the lubrication line, surface roughness of the bearing surface, waviness, roundness, etc. Determined by precision.

Further, when the required minimum oil film thickness reaches the number of rolls that can be cleared, the static pressure effect is no longer necessary, so the high pressure oil supply is stopped and the bearing is operated only by the dynamic pressure effect.

[Problems to be Solved by the Invention]

The above conventional bearing has the following problems to be solved. That is, in recent rolling mills, oil film bearings that can operate under extremely low speed and high load conditions are required, and it has become necessary to enhance the static pressure effect of conventional bearings. Here, the extremely low speed means a roll rotation speed N of about 0 to 5 rpm, and the high load means the maximum load of the dynamic pressure bearing having no static pressure effect.

Enhancing the static pressure effect is to secure the minimum required oil film and to support the high load (maximum load) that acts on the roll shaft. Generally, the static pressure recess size is increased to keep the oil supply pressure at medium to low pressure. On the contrary, there is a method of decreasing the recess size and increasing the oil supply pressure as much as necessary, but the latter is adopted as the load increases due to the capacity of the oil supply pump.

FIG. 10 shows the relationship between the oil supply pressure and the oil amount, and the solid line in the figure represents the capacity of the oil supply pump. On the other hand, the broken line indicates that the relationship between the oil pressure and the oil amount that matches the high load (maximum load) condition value is the static pressure when the oil film thickness is constant and the size of the static pressure recess provided in the bearing load zone is changed. It is obtained by bearing theory. The static pressure recess size becomes smaller as the broken line rises to the upper left.

From the figure, the design of the static pressure part (oil pump, static pressure recess size) is point C between point A and point B where the broken line and the solid line intersect,
That is, the operation is performed at a position where the oil supply pressure and the oil amount are large.

By the way, as a result of the actual machine 1/3 size model test, it was found that the experimental value and the calculated value at the point C were in good agreement at a light load. However, as the load increases, the experimental value falls below the calculated value, and there is a problem that the static pressure effect can be increased only up to about 50% of the target load, that is, the maximum load of the dynamic pressure bearing that does not have the static pressure effect. It became clear.

Generally, the circumferential bearing clearance from the hydrostatic recess to the oil pocket is a slightly expanding divergent clearance. Therefore, as shown in FIG. 11, in the hydrostatic bearing theory, when the amount of movement of the roll shaft center exceeds a certain value, the load capacity that had been increasing up to that point undergoes a reversal phenomenon in which the load capacity is reduced.

The problem clarified by the model test described above is that elastic deformation of the bearing housing began to occur in a non-negligible order in the divergent direction as the load increased, and it fell into the reversal phenomenon range of the load capacity. It was found by a detailed analysis considering the three-dimensional deformation of the bearing housing.

[Means for Solving the Problems]

The present invention, as a means for solving the above-mentioned problems, in an oil film bearing used in a rolling mill roll in which the axial load is upward and a recess for static pressure is provided only in the upper part, in the parts that are the left and right of the axial center when viewed in the axial direction An oil pocket, which has substantially the same cross section over the required axial length and is formed to face the inner circumference, and which gradually becomes shallower as it goes up and down in the circumferential direction; and the oil pocket and the recess for static pressure. A plurality of oil drain grooves that are provided longitudinally in the axial direction on the left and right bearing load surfaces that are in the middle and that are substantially symmetrical in the left and right directions, or a plurality of oil drain holes that are formed by arranging in multiple points in the axial direction. And a static pressure recess and an oil supply hole formed in each of the oil pockets, an oil film bearing with a static pressure effect is provided.

[Work]

Since the present invention is configured as described above, it has the following effects. That is, the left and right bearing load surfaces, which are intermediate between the upper hydrostatic recesses, the left and right oil pockets and the hydrostatic recesses when viewed in the axial direction, are substantially symmetrical in the lateral and axial directions provided longitudinally. Since the inner circumference of the oil film bearing has either a plurality of oil drainage grooves that form a plurality of oil drainage grooves or a plurality of oil drainage holes that are formed by arranging in multiple points in the axial direction, the high static pressure applied to the hydrostatic recess through the oil supply hole The pressure is released from the oil drain groove or oil drain while it reaches the left and right oil pockets, etc., and if there is a high static pressure beyond that, that is, below the vicinity of the oil pocket forming end (upper side). Therefore, elastic deformation of the bearing due to high static pressure hardly occurs.

That is, the high-pressure oil in the static pressure recess portion tends to flow through the narrow bearing gap to the low-pressure side oil pocket forming end portion. If there is a separate flow passage having a significantly smaller oil outflow resistance than the narrow bearing clearance in the middle of this flow passage, most of the oil will pass through this separate flow passage. Therefore, the oil does not flow to the oil pocket forming end side, and the static pressure does not act.

This separate flow path is an oil drain groove that penetrates in the axial direction, and the groove width,
The groove depth is determined so as not to impair the above-mentioned action because it relates to the oil outflow resistance.

By the way, the reason why the groove is provided is that the cause of the deformation in the divergent direction in the current bearing structure is near the oil pocket forming end, based on the hydrostatic bearing characteristic analysis and model test considering the three-dimensional elastic deformation of the bearing housing. This is because it was confirmed that it was due to the moment action of the static pressure applied.

Another reason is that the static pressure applied in the vicinity of the oil pocket forming end is a considerably small value as the component force in the load direction.

In addition, the oil drain groove or oil drain hole is substantially symmetrical when viewed in the axial direction,
Since they are arranged approximately symmetrically in the axial direction, the static pressure is released symmetrically, so that the static pressure load on the inner circumference of the bearing is always symmetric, no asymmetric load occurs, and the generated stress is even. To minimize the elastic deformation of the bearing.

Further, since the left and right oil pockets are formed so as to become shallower in the vertical direction, the lubricating oil is efficiently drawn in with the rotation of the roll shaft, and the lubricity and the dynamic pressure effect are enhanced.

〔Example〕

The first to fourth embodiments of the present invention will be described with reference to FIGS.

In these figures, the bearing box 5, the bearing box bearing 6 and the like having the same structure as the conventional example are not shown. Further, members having the same reference numeral, which are not particularly described, have the same functions as those of the conventional example.

FIGS. 1, 2, 3, and 4 are shells for the first to fourth embodiments of the rolling mill oil film bearing having the static pressure effect with the oil drain groove or oil drain hole according to the present invention. 4 is a plan development view of the load zone surrounded by the oil pocket forming end of FIG. 4 and both ends in the bearing flow direction, and FIG. 5 is a V-V of FIGS. 1, 2, and 3. FIG. 6 shows a sectional view taken along the arrow, and FIG. 6 shows a sectional view taken along the line VI-VI in FIG. First, the first shown in FIG.
In this embodiment, one static pressure recess 10 is provided with one oil drain groove 15 penetrating in the axial direction between the left and right oil pocket 7 and the oil pocket forming ends 8 and 9. FIG. 2 shows a second embodiment, in which the drain oil groove 15 penetrating in the axial direction of FIG. 1 is made a discontinuous non-penetrating type, and a portion in which the drain oil groove at the center of the bearing longitudinal direction is not arranged. It has a great dynamic pressure effect.

Further, FIG. 3 shows a third embodiment, and the recess for static pressure of FIG.
In contrast to 10 pieces, two static pressure recesses 10 are provided in the axial direction as a countermeasure against one side of the shaft, and the oil drain groove 15 is a non-penetrating type.
There are a number of places. In the case of the present embodiment, there is an advantage that the dynamic pressure effect becomes larger than that in FIG. 2 (the oil film bearing for rolling mills also requires the dynamic pressure effect).

FIG. 4 is a view of the fourth embodiment, and instead of the oil drain groove 15 in FIG. 3, several oil drain holes 16 are provided at the same groove position and the same effect is exhibited.

In any of the above first to fourth embodiments, the lubricating oil flowing out from the static pressure recess in the circumferential direction is discharged to the outside of the bearing load zone from the oil drain groove or oil drain hole, and the static pressure is applied near the oil pocket forming end. The purpose is not to act. In the model test, the third embodiment shown in FIG. 3 was adopted, and it was confirmed that the static pressure effect was sufficiently enhanced.

In FIGS. 1 to 6, 17 is an oil pocket oil supply hole, 18 is a recess oil supply hole, and 19 is an axial oil discharge hole.

As described above, according to the first to fourth embodiments, the lubricating oil is discharged to the outside of the load zone of the bearing by the drain groove or the drain hole, so that the deformation of the bearing is suppressed and the static pressure effect of the pressure receiving portion is enhanced. is there. The oil drain groove and the oil drain hole may be used in an appropriate combination. It is not limited to the usage of the embodiment.

〔The invention's effect〕

Since the present invention is configured as described above, it has the following effects. That is, in an oil film bearing for a rolling mill that has both a static pressure effect and a dynamic pressure effect, if the static pressure effect is increased and the oil supply pressure is increased, the bearing box undergoes pressure deformation and, as a result, the pressure in the static pressure recess portion is reduced. It does not rise and the static pressure effect cannot be increased. On the other hand, the bearing having the static pressure action area limiting structure of the present invention produces a static pressure effect twice as high as that of the conventional one, and it is possible to obtain an ultra-low speed / high load capacity oil film bearing required in recent rolling mills. You can

[Brief description of drawings]

FIG. 1 is a development plan view of a first embodiment of the present invention in which one static pressure recess is provided and two oil drainage grooves penetrating in the axial direction are arranged on the circumference, and FIG. 2 shows a static pressure recess. FIG. 3 is a development plan view of a second embodiment of the present invention in which one oil drain groove is provided in four axially non-penetrating oil drain grooves, and FIG. 3 is a plan view showing static pressure recesses in two axially non-penetrating grooves. 4 is a developed plan view of a third embodiment of the present invention in which four oil drain grooves are arranged, and FIG. 4 shows a fourth embodiment of the present invention in which an oil drain hole is provided at the oil drain groove position in FIG. FIG. 5 is a developed plan view, FIG. 5 is a sectional view taken along the line VV of FIGS. 1, 2, and 3, FIG. 6 is a sectional view taken along the line VI-VI of FIG. 4, and FIG. FIG. 8 is a vertical sectional view of a conventional oil film bearing, FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 7, and FIG. 9 is a minimum oil film thickness and a roll shaft of a rolling mill oil film bearing having a static pressure effect. Constant load on the rotating machine Fig. 10 is an explanatory view qualitatively showing the conditions, Fig. 10 is an explanatory view showing the relationship between the oil supply pressure and the oil amount before the recess and the oil supply pump capacity by changing the size of the recess for static pressure and keeping the load condition constant. The figure is a relationship diagram showing the relationship between the amount of movement of the roll shaft center and the load capacity based on the hydrostatic bearing theory as a dimensionless value. 4 …… Ciel 5 …… Bearing box 6 …… Bearing box support, 7 …… Oil pocket 8,9 …… Oil pocket forming end 10 …… Recess for static pressure 13,13 …… End face 15 …… Discharge Oil groove, 16 ... oil drain hole 17 ... oil pocket oil hole 18 ... recess oil hole, 19 ... axial oil hole 20 ... inner surface (of shell 4)

Claims (1)

[Claims] 1. An oil film bearing for use in a rolling mill roll having an axial load directed upward and having a hydrostatic recess provided only on the upper portion of the oil film bearing, which opposes the inner circumference of a portion on the left and right of the axial center when viewed in the axial direction. And the left and right oil pockets, which are intermediate between the oil pocket and the static pressure recess, have substantially the same cross section over the required length in the axial direction and gradually become shallower toward the upper and lower sides in the circumferential direction. Any of a plurality of oil drain grooves that are provided longitudinally in the axial direction on the bearing load surface and that are substantially symmetrical in the left and right direction, or a plurality of oil drain holes that are formed by arranging in a multi-point manner in the axial direction, An oil film bearing with a hydrostatic effect, comprising a hydrostatic recess and an oil supply hole formed in each of the oil pockets.