WORM AND RACK REST BAR ASSEMBLY

Abstract

A rest bar assembly for a guide that is employed in a rolling mill to direct a hot rolled product either entering or exiting from the roll pass of a roll stand. The rest bar assembly comprises a core extending transversely with respect to the mill pass line. A saddle is movable along the core and is adapted to carry the guide. An adjustment mechanism serves to move the saddle along the core. The adjustment mechanism comprises a worm rack extending along a back side of the core, and a rotatable worm carried by the saddle and in meshed relationship with the worm rack.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No. 61/838,972 filed 25 Jun. 2013, the entire contents and substance of which are herein incorporated by reference.

BACKGROUND

1. Field

Embodiments of the present invention relate to rest bar assemblies employed in rolling mills to support guides on the entry and exit sides of the roll stand housings, and are concerned in particular with an improved rest bar assembly having a novel adjustment mechanism for laterally adjusting the guides with respect to the mill pass line.

2. Description of Related Art

In the process of hot rolling long products, e.g. rods, bars and the like, guides are employed to accurately present and receive the products from one roll stand to the next. In order to achieve quality results, the guides must be accurately positioned and firmly held in place with respect to the mill pass line.

With reference to FIGS. 7 and 8, the typical standard traversing rest bar assembly comprises a core 10 extending traversely with respect to the mill pass line “PL,” with integrally formed mounting plates 12 serving to secure the core to housing posts 14a, 14b of a roll stand. A saddle 16 is carried on the core. A guide 18 is mounted on the saddle and held in place between a fixed jaw 20 and a coacting adjustable jaw 22.

When an operator wishes to adjust the position of the guide 18 with respect to the mill pass line PL and along the mill rolls 24, a clamping mechanism 26 is loosened, allowing the saddle 16 to move relative to the core 10. The saddle is adjusted by an adjusting mechanism 28. The typical adjusting mechanism is a long threaded shaft extending through and held in place by the core 10. The threaded shaft is in engagement with a nut that is held in place by the saddle. When the shaft is turned, the nut is moved along the shaft, carrying with it the saddle in the desired direction.

This type of design is prone to many types of problems including binding of the nut on the threaded shaft, bending of the threaded shaft, seizing of the nut to the shaft, physical damage to the threads on the threaded shaft or nut or both. In a situation where the nut is stuck in place and cannot be removed, the nut or shaft or both must be destroyed to remove and replace them. There are many variations on this type of traversing mechanism, but most rely on the same principal of a threaded shaft and a nut.

Another disadvantage to this design is that in order to reduce the likelihood of the adjustment mechanism binding, the threaded shaft must be located as close as possible to the center of the adjustable saddle 16, which combined with the requirement that the shaft must usually be behind the housing posts 14a, 14b for operator access, creates a situation where the saddle becomes excessively large. This large size combined with being back away from the mill rolls 24 causes the adapter plates for the guides to be excessively large and overhung. Not only does this increase weight, material usage, and cost, it also increases the torsional loading that is applied to the rest bar assembly during rolling.

Another drawback independent of those associated with the adjusting mechanism relates to the mounting plates 12 that mount the rest bar assembly to the mill stand. Each mill manufacturer and each stand size and generation from a particular manufacturer have a variety of different mounting configurations, which makes supplying an aftermarket rest bar assembly more difficult and costly. In the typical traversing rest bar design, the core 10 is made such that the mounting plates 12 and the core comprise a single weldment or casting with the mounting features machined as necessary. This type of design is good for rigidity, but requires a new design and assembly for each different mounting configuration. This wastes time and money, and unduly complicates the task of inventoring rest bar assemblies to meet future customer demands.

SUMMARY

Broadly stated, embodiments of the present invention address the above described problems in part by providing an improved rest bar assembly with a novel adjustment mechanism.

In exemplary embodiments of the present invention, the rest bar assembly comprises a central fixed core, removable keyed mounting plates, and a traversable saddle. An adjustment mechanism comprises a helically cut rack that is mounted externally on a back side of the fixed core, and a worm carried by the saddle that meshes collinearly with the rack. The meshing of the worm and rack is such that it is self-locking, so that when the rest bar is mounted in a vertical orientation, and the saddle is unclamped, the saddle will not move down the core without turning the worm. Additionally, if damaged, which is less likely due to their significantly more robust design, the worm and rack can be easily separated with minimal work and no damage. The mesh of the worm and rack do not require perfect adjustment, and are thus less susceptible to binding.

In other exemplary embodiments of the present invention, the mounting plates are separate from and are detachably secured to the core. With this arrangement, the basic core design, in different lengths, can be mass produced and inventoried, with only the mounting plates requiring different designs needed to accommodate differently configured roll stands.

These and other objects, features and advantages of the present invention will become more apparent upon reading the following detailed description in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a rest bar assembly in accordance with an exemplary embodiment of the present invention supporting a guide on the entry side of a rolling mill roll stand;

FIG. 2 is a side view of the rest bar assembly depicted in FIG. 1, with the nearest housing post removed;

FIG. 3 is a perspective view of the rest bar assembly depicted in FIGS. 1 and 2, with the housing posts and mounting plates removed;

FIG. 4 is an exploded perspective view of the rest bar assembly;

FIG. 5 is a rear view of the rest bar assembly, with the mounting plates detached from the core;

FIG. 6 is an enlarged sectional view taken along line 6-6 of FIG. 5;

FIG. 6A is an enlarged view of the circled portion in FIG. 6;

FIG. 7 is a perspective view of a conventional rest bar assembly; and

FIG. 8 is a side view of the conventional rest bar assembly supporting a guide in a typical rolling mill installation.

DETAILED DESCRIPTION

The components described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable components that would perform the same or a similar function as well as the materials described herein are intended to be embraced within the scope of the present invention.

Referring now to the figures, wherein like reference numerals represent like parts throughout the views, embodiments of the present invention will be described in detail.

With reference initially to FIGS. 1 and 2, the entry side of a rolling mill roll stand 32 is partially depicted as comprising housing posts 34a, 34b and a pair of multigrooved work rolls 36. The roll stand 32 is arranged along the mill pass line PL in series with other roll stands (not shown).

A guide 38 serves to direct a hot rolled product along the mill pass line PL into a roll pass defined by a selected pair of the grooves in the work rolls 36. A rest bar assembly 40 in accordance with an exemplary embodiment of the present invention is positioned to support the guide 38 in its operative position.

With reference additionally to FIGS. 3-6, the rest bar assembly 40 comprises a core 42 extending transversely with respect to the mill pass line PL. Separable mounting plates 44 are detachably secured, for example by being keyed and bolted to opposite ends of the core 42. The mounting plates are configured and dimensioned for attachment to the housing posts 34a, 34b. The core 42 has a front side 42a arranged to face the rolls 36, and an oppositely facing back side 42b.

A saddle 46 is mounted for movement along the core 42. The guide 38 is carried by the saddle 46 and may be removably fixed between a fixed jaw 48a and an adjustable clamping jaw 48b.

An adjustment mechanism for moving the saddle 46 along the core 42 comprises a helically cut worm rack 50 extending externally along the back side 42b of the core 42. A worm gear 52 is carried by the saddle 46 on a rotatable shaft 54, and is meshed relationship with the worm track 50. Rotation of shaft 54 and the worm gear 52 serves to shift the saddle 46 along core 42.

The position of the saddle 46 on the core 42 may be releasably fixed by a clamp mechanism, one example being the remotely operable hydraulically actuated clamp 56 best seen in FIG. 6.

The shaft 54 may be rotatively adjusted by a remotely operable motor 58. Although not shown, it is to be understood that where remote operation is not required, both the shaft 54 and the clamp 56 may be designed for manual adjustment by mill personnel.

In light of the foregoing, it will now be appreciated by those skilled in the art that the worm and rack rest bar design of the present invention solves most if not all of the problems associated with conventional rest bars. The worm 52 and rack 50 adjustment mechanism is far less susceptible to binding, and its location along the back side 42b of the core 42 provides unprecedented access by mill personnel while allowing the saddle 46 to be locked as far into the mill stand as desired. With the saddle thus located in close proximity to the work rolls 36; the adapter plates 44 for the guiding equipment can be greatly reduced in size, making it possible to reduce costs, weight and torsional loading.

Although the next bar assembly of the present invention has been shown supporting a guide for directing a hot rolled product into a roll pass, it will be apparent to those skilled in the art that the innovative features of the present invention can be incorporated into a rest bar assembly supporting a guide for directing a hot rolled product exiting from the roll pass.

Only the separable mounting plates 44 need be designed specially to suit different housing designs, thus allowing the core to be produced in a standard design at different lengths.

Claims

1. In a rolling mill in which a guide directs a hot rolled product either into or out of a roll pass aligned on a mill pass line, a rest bar assembly for supporting said guide and for transversely adjusting said guide with respect to the mill pass line, said guide comprising:

a core extending traversely with respect to the mill pass line;

a saddle movable along said core, said saddle being adapted to carry said guide;

an adjustment mechanism for moving said saddle along said core, said adjustment mechanism comprising a worm track on said core, a worm gear carried by said saddle and in meshed relationship with said worm track; and

means for rotatably adjusting said worm gear.

2. The rest bar assembly of claim 1, further comprising a clamping mechanism operable in a clamping mode to fix the position of said saddle on said core, and in a release mode permitting shifting of said saddle along said core.

3. The rest bar assembly of claim 1, wherein said core has a front side arranged to face the roll pass, and a backside, and wherein said worm track extends along said backside.

4. The rest bar assembly of claim 1, wherein said worm track is helically cut.

5. The rest bar assembly of claim 1, further comprising mounting plates detachably secured to opposite ends of said core, said mounting plates being configured and dimensioned for attachment to a housing structure containing work rolls defining said roll pass.

6. The rest bar assembly of claim 1, wherein said means for rotatably adjusting said worm gear comprises a remotely operable drive motor.

7. The rest bar assembly of claim 2, wherein said clamping mechanism is hydraulically actuated and remotely operable.

8. A rest bar assembly for supporting a guide configured and arranged to direct a hot rolled product either entering or exiting from a roll pass aligned on the pass line of a rolling mill, said rest bar assembly comprising:

a core extending transversely with respect to the mill pass line, said core having a front side arranged to face the roll pass, and an oppositely facing back side;

a saddle moveable along said core, said saddle being adapted to carry said guide;

an adjustment mechanism for moving said saddle along said core, said adjustment mechanism comprising a worm track extending along the back side of said core, and a worm gear carried by said saddle and in meshed relationship with said worm track; and

means for rotatably adjusting said worm gear.