CN1301809C - Triple bearing arrangement for cantilevered roll shafts - Google Patents

Abstract

A rolling stand of a rolling mill comprising: parallel roll shafts rotatably supported by first and second axially spaced bearings contained within parallel eccentric sleeves. The eccentric sleeve is rotatably supported in a casing, and the roll shaft has a cantilever end protruding outward from one side of the casing and adapted to carry working rolls. A third oil film bearing is contained by an eccentric sleeve arranged to rotatably support the roller shaft at an intermediate portion between and axially spaced from the first and second bearings.

Description

Three-bearing structure of the cantilever roller shaft

technical field

This invention relates generally to rolling mills for rolling long products such as rods, rods, and the like, and in particular to improvements in so-called "cantilever" rolling stands in which the work rolls are mounted on the ends of support shafts .

Background technique

Cantilevered work rolls are traditionally mounted on the ends of parallel support shafts. The shafts are journalled for rotation in axially spaced work and drive side bearings contained in eccentric sleeves which are mounted in a housing box for rotational adjustment. The roller bearings carry gears which are arranged to mesh with the gears of the mill drive and to simultaneously turn the eccentric sleeves in opposite directions to adjust the work rolls symmetrically with respect to the pass line.

A more detailed description of this conventional structure can be found in US Patent No. Re 28,107, which is incorporated herein by reference.

With the advent of smaller diameter work rolls, the roll shaft diameter must also be reduced, resulting in an excessively long shaft length compared to the shaft diameter. While the conventional two bearing arrangement meets the strength requirements reasonably well, it does not meet the stiffness requirements so that shaft deflection becomes a problem.

One approach to this problem is disclosed in US Patent No. 6,561,003 (Grimmel). Here, pressure sleeves are used between conventional work and drive side bearings. The pressure sleeve is hydrostatically loaded and remotely controlled to preload the shaft, thereby counteracting its tendency to deflect under load. In addition to being overly complex and expensive, the structure is not sufficiently rigid because the roller shaft is contained only by pressure sleeves which lack critical radial support from the surrounding housing box.

Contents of the invention

According to the invention, additional shaft stiffness is provided by providing a third bearing between the conventional work and drive side bearings. The third bearing is of the "oil film" type, in which the shaft is journalled for rotation on an oil film held hydrodynamically at the bearing loading area. Oil film bearings have a self-modulating stiffness that increases in proportion to the eccentricity of the bearing without the need to introduce pressurized oil in a manner that individually controls the hydrostatic pressure. Furthermore, the third bearing is radially supported by the eccentric sleeve and housing box, thus providing increased stiffness compared to known prior art arrangements.

The above and other features and advantages of the present invention will now be described in more detail with reference to the accompanying drawings.

Description of drawings

Figure 1 is a longitudinal sectional view taken through a cantilevered rolling stand embodying the concepts of the present invention;

Figure 2 is a cross-sectional view taken along line 2-2 of Figure 1;

Figure 3 is an enlarged view of a portion of Figure 2; and

Fig. 4 is a graph showing how the stiffness of the third oil film bearing increases in proportion to the eccentricity of the bearing.

Detailed ways

Referring first to FIGS. 1 and 2 , the roll shaft 10 is rotatably supported by drive and work side sleeve bearings 12 , 14 contained within an eccentric sleeve 16 . The eccentric sleeve is journalled within housing box 18 for rotation and rotatable adjustment. The cantilevered outboard end 10a of the roll shaft is configured to support work rolls (not shown), while the cantilevered inboard end carries gears 20 constructed and arranged to mesh with drive gears (not shown) of the mill drive.

The middle portion of the roller shaft is journalled for rotation on a third bearing 22 contained in the middle portion of the eccentric sleeve 16, and the middle portion of the eccentric sleeve is tightly accommodated in the housing box and thus firmly enclosed by the housing. box support. The bearing 22 is of the sleeve type, lubricated by oil, and the rotation of the shaft creates a hydrodynamic oil film at the loaded area of the bearing.

In particular, as best seen in FIG. 3 , housing box 18 is provided with an inlet passage 24 which communicates with an arcuate slot 26 contained in a bore in eccentric sleeve 16 . A radial channel 28 leads from the slot 26 to a second arcuate slot 30 in the bore of the eccentric sleeve. The sleeve bearing 22 has a radial passage 32 communicating with the groove 30 .

During operation of the rolling mill, oil is supplied through passage 24, groove 26, passage 28, groove 30 and passage 32 into the operating gap between the journal surface of shaft 10 and the inner bearing surface of sleeve 22 . In the loaded zone of the bearing, the oil hydrodynamically forms a wedge-shaped film.

When the roll shaft is loaded due to separation forces exerted on the cantilevered work rolls, the deflection of the shaft will be resisted by the bearings 22 . Since the roller shaft tends to flex under load, Figure 4 shows how the bearing 22 hydrodynamically increases in stiffness in response to increased eccentricity of the journal surfaces within the bearing. The increase in bearing stiffness is self-modulating and does not require separate application of pressurized oil nor remote control.

The eccentric sleeve 16 is of solid design, the middle part of which extends continuously between the drive and working side bearings. This, combined with the support of the mid-section of the eccentric sleeve by the housing box and the self-regulating counterbalancing forces created by the bearings 22, all contribute to greatly increasing the overall stiffness of the roll assembly.

Claims (5)

1. the roll stand of a milling train, it comprises:

Parallel roll shaft, it is rotationally by first and second bearings supporting at interval vertically;

The parallel eccentric adjusting sleeve that comprises described bearing, described eccentric adjusting sleeve are rotatably supported in the shell, and described roll shaft has the cantilever end of giving prominence to and be suitable for carrying work roll outside a side direction of described shell; And

The 3rd bearing that is comprised by described eccentric adjusting sleeve, described the 3rd bearing is arranged between described first and second supportings, also locates the described roll shaft of rotatably support with the isolated middle part of described first and second bearings vertically, to be bearing in described shell interior with rotation described eccentric adjusting sleeve axle journal, and radially supported by described shell at place, described middle part.

2. roll stand as claimed in claim 1 is characterized in that, described the 3rd bearing is a filmatic bearing.

3. roll stand as claimed in claim 1 is characterized in that, described roll shaft has from the second outwards outstanding cantilever end of the opposite side of described shell, and described second cantilever end is suitable for supporting travelling gear.

4. roll stand as claimed in claim 1 is characterized in that, described the 3rd bearing is the sleeve bearing of oil lubrication, and it has the degree of eccentricity that is proportional to the journal surface in the described bearing and the rigidity of the automodulation that increases.

5. the roll stand of a milling train, it comprises:

Parallel roll shaft, it is rotationally by isolated first and second bearings supporting vertically;

The parallel eccentric adjusting sleeve that comprises described bearing, described eccentric adjusting sleeve are rotatably supported in the shell, and described roll shaft has the cantilever end of giving prominence to and be suitable for carrying work roll outside a side direction of described shell; And

The 3rd bearing that is comprised by described eccentric adjusting sleeve, described the 3rd bearing is arranged between described first and second supportings, also locates the described roll shaft of rotatably support with the isolated middle part of described first and second bearings vertically, described the 3rd bearing is the sleeve bearing of oil lubrication, and it has the degree of eccentricity that is proportional to its corresponding journal surface and the rigidity of the automodulation that increases.