US3482426A - Tension roll housing for cold strip mills - Google Patents

Description

Dec. 9, 1969 H. G. BARGFELDT 3,482,426

TENSION ROLL HOUSING FOR COLD STRIP MILLS Filed May 15, 1967 l IN [1 Affomey United States Patent M 3,482,426 TENSION ROLL HOUSING FOR COLD STRIP MILLS Howard G. Bargfeldt, Hanover Township, Lake County, Ind., assignor-to United States Steel Corporation, a corporation of Delaware Filed May 15, 1967, Ser. No. 638,240 Int. Cl. B21b 39/08 US. Cl. 72-205 3 Claims ABSTRACT OF THE DISCLOSURE A roll stand housing having separate roll mounting windows therein respectively for the work rolls and for a tension roll assembly in a cold strip rolling mill, the arrangement of both windows in a common housing operating to reduce to a minimum the length of the strip between said tension roll assembly and the reducing pass of said work rolls.

This invention relates to mills for cold rolling steel strip and is directed, more particularly, to an improved mounting for tension rolls used either to apply forward or back tension to strip moving through a reducing pass between a pair of work rolls. The improvements of the invention are obtained, more specifically, by reducing the distance over which the strip must travel between the reducing pass and the tension rolls. In a manner to be described the improved tension roll mounting of this invention is effected by providing a housing with a roll mounting window therein for the tension rolls in addition to the customary window in which the strip work rolls are mounted.

Tension roll assemblies are commonly employed in cold strip mills for regulating forward or back tension on strip moving through a reducing pass between the work rolls of a roll stand. As shown, for example, in C. E. Moore Patent No. 2,176,094 and in C. J. Klein et al. Patent No. 2,287,380, assemblies of this type comprise a vertically spaced pair of rolls over which the strip is wound in reverse directions so that the portion of the strip momentarily engaged with such rolls has an S-shaped configuration. Such assemblies are usually mounted either in separate roll housings spaced from the housing for the strip work rolls or, as shown in the above patents, are supported by brackets secured to the work roll housings. With tension roll mountings of this character, the strip travels over a considerable distance, usually several feet, between the work roll reducing pass and the point of its engagement with the tension rolls.

In the operation of cold strip mills with tension roll assemblies and mountings therefor of the type indicated above, the problem of maintaining flatness and tension uniformly over the width of the strip moving to or from the tension rolls has proved troublesome, particularly when rolling thinner gauges. In this respect, the strip when stretched by the pulling action of the tension rolls has a tendency to shrink or neck-in on itself in a transverse direction, and non-uniform tension over the width of the strip results in the development of longitudinal folds or wrinkles. In addition, stretch levelling techniques used to compensate for this frequently cause edge-cracking and strip breakage.

One of the principal objects of this invention, accordingly, is to provide a rolling mill which will minimize the elongation and transverse necking forces that cause the operating problems referred to above. In accordance with the principles of this invention, this is accomplished by providing a tension roll mounting which reduces the distance between the tension roll assemblies and the mill work rolls and results in a more compact mill.

3,482,426 Patented Dec. 9, 1969 A related and more specific object of the invention is to provide in a cold strip mill a roll stand housing having separate windows respectively providing for the mounting therein of the work rolls and the tension roll assemblies, and in which the horizontal spacing of such windows as well as the distance between the tension rolls and the work rolls is a minimum, to thereby minimize the action of the elongation and necking forces when the strip is stretched longitudinally.

Other objects and advantages of the invention will become apparent from the following description.

In the drawings, there is shown a preferred embodiment of the invention. In this drawing:

FIGURE 1 is a side elevational view of a roll stand housing having a tension-roll mounting therein constructed in accordance with the principles of this invention;

FIGURES 2 and 3 are sectional views taken respectively along the lines IIII and IIIIII of FIGURE 1, FIGURE 3 being drawn to an enlarged scale; and

FIGURES 4, 5 and 6 are perspective views of parts of the mounting for the tension rolls shown in the preceding figures.

FIGURES 1 and 2 of the drawings show the manner in which the invention is applied to a 4-high strip mill that includes a pair of work rolls 1 and a pair of backup rolls 2. The rolls 1 and 2 are supported by hearing chocks (not shown) in windows 3 between laterally spaced bearing posts 4 and 4a of roll housings 5 at opposite sides of the mill. The drive for rotating the rolls 1 and 2 operates them to deliver the strip S through a reducing pass between the work rolls 1 to a tension roll assembly 6. Reduction of the strip thickness is regulated in the usual manner by a screw-down mechanism (not shown) which controls the size of the rolling pass between the rolls 1. The tension roll assembly 6 comprises a vertically spaced pair of rolls 7 over which the strip S is wound in reverse directions so that the portion of the strip engaged with such rolls has an S-shaped configuration to provide contact with the rolls 7 over a maximum area. From the lower roll 7, the strip S travels upwardly to a tensiometer roll 8 and then horizontally over a deflector roll 9 for delivery to a winding reel. The drive for the rolls 7 includes drive shafts 10 that are operated conventionally to maintain the portion 11 of the strip between the work rolls 1 and tension rolls 7 under the desired forward tension, and to deliver the portion of strip 12 extending between the lowermost rolls 7 and the tensiometer roll 8 to a Winding reel under minimum tension.

In accordance with the principles of this invention, the roll housings 5 are constructed to provide a mounting therein for the tension roll assembly 6 and in such manner that the upper tension roll 7 is positioned as close as possible to the rolling pass between the work rolls 1 to thereby reduce the length of the strip 11 between the rolls 1 and the tension assembly 6 to a minimum. For this purpose, the posts 412 of the roll stand housings 5 at opposite sides of the mill are cast with enlargements 14 having windows 15 therein that provide a removable support for the tension rolls 7 in a manner to be described. By forming the windows 15 in the posts 4a, the

upper tension roll 7 is located closer to the rolling pass between the work rolls 1 than was heretofore possible with the conventional bracket supports and separate tension roll stands used previously to support the tension The windows are rectangular in shape and extend vertically and parallel to the windows 3 in which the rolls 1 and 2 are supported. Each of the windows 15 is defined by spaced side Walls 1-6 and spaced end walls 17. The support for the opposite ends of the rolls 7 in the windows 15 comprises a pair of bearing blocks 18, each of which has a pair of vertically spaced openings 19 in which the journals 20 at opposite ends of the rolls 7 are rotatably supported by bearings 21. Key blocks 22 and 23 bolted respectively to the upper and lower end walls 17 of the windows 15 are formed with key Slots 24 in which keys 25 secured to the blocks 18 are received to hold the rolls 7 against endwise movement in the windows 15. Movement of the blocks 18 in the windows 15 is further restricted by bars 26 and 27 that are attached to the upper and lower ends of the blocks 18. Removable pins 28 extending through aligned openings 29 in the lower arms 27 and key blocks 23, and cap screws 30 extending through threaded openings 31 in the upper arms 26, key blocks 22 and bearing post 4a hold the blocks in their assembled position in the windows 15. The mount ing of the bearing blocks 18 in the windows 15 provides for removal of the rolls 7 with respect to the housings 5 as a unit when repair or replacement is required. For this purpose, it is only necessary to remove the pins 28 and screws 30 so that the blocks 18 can be moved in a sidewise direction to disengage the keys 25 from the keyways 24. The assembly of the bearing blocks 18 and rolls 7 may then be removed as a unit from the housings 5 by endwise movement through the windows 15.

As best shown in FIGURE 3, the vertical spacing of the arms 26 and 27 is less than the spacing of the adjacent faces 32 of the key plates 22 and 23 to provide for free axial movement of the assembly of rolls 7 and blocks 18 to their mounted positions. In addition these dimensions provide a space 33 between the arm 26 and key plate 22 which may be varied by tightening the bolt 30 to adjust the vertical position of the tension roll assembly 6 and thereby the horizontal position of the passline of the strip portion 11 relative to the working pass between the rolls 1.

The width of the windows 3 is slightly greater than the diameter of the backup rolls 2, this being necessary in order that the rolls 2 may be removed axially through the windows 3. Similarly, the windows 15 have a width which is slightly larger than the diameter of the tension rolls 7 to permit their removal and replacement by axial movement through the windows 15. By reason of the provision of the windows 15 in the housings 5, it will be apparent that the maximum length of the strip portion 11 need be only slightly greater than the sum of the radii of the backup rolls 2 and the tension rolls 6, plus the thickness of the columns at the left of the windows 15 as viewed in FIGURES 1 and 2. However, it will be noted further that the mounting of the rolls 7 that is provided by the key blocks 22 and 23 provides for a further reduction in the length of the strip portion 11. By reason of the key slots 24 in the blocks 22 and 23, the bearing blocks 18 are moved to the left as viewed in FIGURES 1 and 2 to positions in which they have abutting engagement with the sidewalls 16 at the left of the windows '15, and in these positions the peripheries of the rolls 7 are located beyond the left side walls 16 and thus closer to the adiacent sidewall 34 of the window 3. This arrangementthus further reduces the length of the strip portion 11 by at least a portion of the width of the columns 4c.

While the foregoing describes the invention for the mounting of the tension rolls 7 which is provided by the windows 15 of this invention in the housings 5 reduces the length of the strip portion 11 between the tension rolls 7 and the reducing pass between the work rolls 1. By reducing the length of the strip portion 11 over which the tension applied by the rolls 7 is effective, it will be apparent that the elongation of the strip by such tension is reduced to a minimum and that the necking-in and stretching actions that give rise to the formation of longitudinal folds and edge-cracking are also minimized.

While the foregoing describes the invention for the mounting of a tension roll assembly 6 in a window 15 in the column 4a for applying forward tension to strip moving through the working pass of the rolls 1, it will be understood that the invention may also be used to apply back tension to the strip. For this purpose the bearing post 4b at the left of the window 3 need only be provided with a window 15 and a tension roll assembly 6 mounted therein as described above for the bearing post 4a. With this modification in mind, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. In a rolling mill of the type having a set of work rolls defining a working pass for reducing the thickness of steel strip and a set of vertically spaced tension rolls over which the strip is wound in reverse directions and travels over an S-shaped path for maintaining the strip between said work and tension rolls under tension, a roll stand comprising a housing having a pair of horizontally spaced windows therein, one of said windows providing a mounting for said set of work rolls therein, and means including the other of said windows for mounting said set of tension rolls in said housing.

2. The invention defined in claim 1 characterized by said tension roll mounting means comprising a pair of key plates secured to the upper and lower edges of said other windows, each of said plates having a key slot opening in a direction away from said roll pass, bearing blocks for rotatably supporting said tension rolls, said blocks having keys secured thereto and projecting vertically from the upper and lower edges thereof for engagement in said key slots, said bearing blocks and said tension rolls being movable toward said Work rolls to shorten the distance therebetween upon movement of said keys into said key slots, engagement of said keys in said key slots being effective to hold said bearing blocks and tension rolls against endwise movement in said other windows.

3. In a mill for cold rolling steel strip, the combination with a set of work rolls defining a working pass for reducing the strip passing therethrough, and a set of vertically spaced tension rolls over which the strip is wound in reverse directions and travels over an S-shaped path for maintaining the strip between said work and tension rolls under tension, of a roll stand comprising a housing having a first window for supporting said set of work rolls therein and a second window spaced horizontally with respect to said first window, and means for mounting said set .of tension rolls in said second window.

References Cited UNITED STATES PATENTS 1,467,880 9/ 1923 Roemer 72-205 2,137,611 11/1938 Hetler 72-205 2,195,009 3/ 1940 Lessmann et a1 72-205 2,287,380 6/ 1942 Klein et al 72-205 3,136,184 6/1964 Wells 72-205 3,210,981 10/1965 Sendzimir 72-234 MILTON S. MEHR, Primary Examiner

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