US3391557A

US3391557A - Gauge control rolling mills and methods of rolling

Info

Publication number: US3391557A
Application number: US410466A
Authority: US
Inventors: Thomas A Fox
Original assignee: Fox Industries Inc
Current assignee: Fox Industries Inc
Priority date: 1964-11-12
Filing date: 1964-11-12
Publication date: 1968-07-09
Anticipated expiration: 1985-07-09
Also published as: DE1427884B2; DE1427884A1; GB1122659A

Description

y 9, 1968 T. A. FOX 3,391,557

GAUGE CONTROL ROLLING MILLS AND METHODS OF ROLLING Filed Nov. 12, 1964 Fig .2.

Fig.4.

INVENTOR Z Thomas A. Fox

United States Patent 01 hoe 339L557 Patented July 9, I968 3,391,557 GAUGE (JON'IROL ROLLING MILLS AND METHODS 01*" EQLLING Thomas A. Fox, Youngstown, Ohio, assignor to Fox Industries, Inc. Filed Nov. 12, 1964, Ser. No. 410,466 8 Claims. (Cl. 72-16) This invention relates to gauge control rolling mills and methods of rolling and particularly to a rolling mill prestressed to a level producing a given reduction on normal entering strip and means varying the mill stress as the strip thickness deviates from the average or norm to produce a final uniform gauge strip.

The problem of producing a metal strip of uniform gauge is one that has long plagued the metal working industry. Various attempts have been made to control the gauge of strip but with less than satisfactory results. The problem arises because of the fact that the stock entering the rolling mill is itself not uniform. Accordingly, a

mill set to produce a given reduction will produce strip which has been substantially uniformly reduced but which is not of uniform gauge. For example, a mill which is set to provide a reduction of 0.005 inch will not discriminate between thick and thin areas on the entering strip but will produce an average of 0.005 inch reduction on all parts of the strip. The resulting finished strip will accordingly be reduced 0.005 inch but will still have thick and thin areas. The problem is to provide a mill and method of rolling which will reduce the thick portions a greater amount and the thin portions a lesser amount than the norm.

I have developed a mill and method of rolling which will accomplish this ideal of reducing thick areas a proper proportion more than the norm and the thinner areas a lesser amount to produce a strip of extraordinary uniformity.

Preferably, I provide work rolls on opposite sides of a strip passline adapted to receive a strip to be reduced therebetween, journals at the ends of said work rolls, a housing carrying said joumals, means in said housing adapted to load said housing and roll journals to an initial load equivalent to a preselected reduction on the average thickness of a strip entering the mill, means for varying said load on the housings and journals when the strip thickness changes from said average thickness and means for measuring strip thickness controlling the means for varying the load to increase the load as the strip thickness increases and decrease the load as the strip thickness decreases. The loading on the housings is preferably accomplished by hydraulic cylinders and may be controlled by known commercial servo mechanisms such as those manufactured by Vickers Company, in turn controlled by the amplified signal from a conventional strip thickness gauge such as the Pratt and Whitney X-ray or beta ray gauges.

In the practice of the method of this invention, a mill housing with work rolls is preloaded to a level representing a preselected reduction on the average thickness of the entering strip. The preload is varied up or down depending upon increases or decreases in entering strip thickness. For example, assuming that a preload of 500,000 pounds represents a reduction of 0.005 inch in a given strip, a decrease in the preload to zero would mean no reduction and an increase of preload to 1,000,000 pounds would mean a reduction of 0.010 inch.

In the foregoing general description I have set out certain objects, purposes and advantages of my invention. Other objects, purposes and advantages of my invention will be apparent from a consideration of the following description and the accompanying drawings in which FIGURE 1 is a side elevation of a mill incorporating my invention showing a schematic control system;

FIGURE 2 is a section on the line 11-11 of FIGURE 1;

FIGURE 3 is a side elevation of a mill embodying a second embodiment of my invention;

FIGURE 4 is a side elevation of a mill embodying a third embodiment of my invention;

FIGURE 5 is a side elevation of a mill embodying a fourth embodiment of my invention; and

FIGURE 6 is a side elevation of a mill embodying a fifth embodiment of my invention.

Referring to the drawings, I have illustrated a housing 10 having a window 11 carrying an upper back up roll chock 12 and a lower back up roll chock 13 with back up

rolls

14 and 15 respectively journaled therein. The upper back up roll chock 12 is provided with a recess 16 carrying an upper work roll chock 17. The lower back up roll chock 13 is provided with a like recess 18 having a work roll chock 19 therein. A conventional screw-down 20 is provided to urge the back up

roll chocks

12 and 13 toward each other.

Hydraulic cylinders

21 and 22 are placed between the back up roll chocks to exert a prestress load on the housing 11. Preferably, the initial stress for a reduction of 0.005 inch is about 500,000 pounds. A strip 23 entering the nip of the work rolls passes between a conventional B-ray gauge head 24 such as that manufactured by Pratt and Whitney which transmits a thickness measurement through a conventional amplifier 25 to a conventional servo valve 26 between a source of hydraulic fluid 27 under pressure and the

cylinders

21 and 22. When a thin spot appears on the strip, the pressure on

cylinders

21 and 22 is reduced in proportion to the relationship between the actual reduction required and the set average. For example, if the average reduction is 0.005 inch and the prestress pressure is 500,000 pounds and an area is noted which is 0.002 inch under the average strip thickness, the prestress is reduced to 300,000 pounds so that the reduction is 0.002 inch less than average. On the other hand, if the area is thicker than average, the pressure on

cylinders

21 and 22 is increased and the reduction is correspondingly greater.

In FIGURES 3 through 6, I have illustrated other embodiments in which the prestress cylinders are located in different positions and combinations. For example, in FIGURE 3 I have placed prestress cylinders and 41 between the back up roll chocks and cylinders 43 and 44 between the top back up roll chock and the top of the window in the housing. In FIGURE 4 I have placed the

prestress cylinders

45 and 46 between the top back up roll chock and the top of the window in the roll housing. In FIGURE 5 I have placed

prestress cylinders

47 and 48 between the back up roll chocks and have incorporated the roll bending cylinders of my Patent 3,024,679 to control the strip contour. In FIGURE 6 I have illustrated an hour glass form of roll housing in which the Work roll chocks 50- and 51 are held between

shoulders

52 and 53 projecting inwardly from the sides of the window 54 of the roll housing 55.

Prestress cylinders

56 and 57 are mounted in the

shoulders

52 and 53 to bear against the bottom back up roll chock 58. I also provide work roll bending cylinders 5960 and 6162 as described in my Patent 3,024,679. In all of the forms illustrated in FIGURES 3 through 6, a conventional thickness gauge and servo valve are used to control the prestress pressure as described in connection with FIGURES 1 and 2.

While I have illustrated and described certain preferred embodiments and practices of my invention in the foregoing specification, it will be understood that this invention may be otherwise embodied within the scope of the following claims.

I claim:

1. A rolling mill structure comprising work rolls on opposite sides of a strip passline receiving a strip to be reduced therebetween, journals at the ends of said work rolls, a housing carrying said journals, a first load means in said housing urging the work rolls together and adapted to load said housing and roll journals to a preselected constant load, a variable load means in said housing adapted to act in opposition to said first load means to load said housing and roll journals to an initial load equivalent to a preselected reduction on the average thickness of a strip entering the mill, means for varying said variable load on the housings and journals when the strip thickness changes from said average thickness and means for measuring strip thickness controlling the load varying means to increase the load as the strip thickness increases above said average and decrease the load as the strip thickness decreases below said average.

2. A rolling mill structure comprising work rolls on opposite sides of a strip passline receiving a strip to be reduced therebetween, journals at the ends of said work rolls, a housing carrying said journals, a first load means in said housing urging the work rolls together and adapted to load said housing and roll journals to a preselected constant load, a variable load means in said housing adapted to act in opposition to said first load means to load said housing and roll journals to an initial load equivalent to a preselected reduction on the average thickness of a strip entering the mill, means for varying said variable load on the housings and journals when the strip thickness changes from said average thickness and means preceding the work rolls adjacent the strip passline for measuring strip thickness controlling the load varying means to increase the load as the strip thickness increases above said average and decrease the load as the strip thickness decreases below said average.

3'. A rolling mill structure comprising back up rolls on opposite sides of the strip passline, work rolls between said back up rolls receiving a strip to be reduced therebetween, journals at the ends of each of said back up rolls and said work rolls, a housing carrying said journals, a first load means in said housing urging the work rolls together and adapted to load said housing and roll journals to a preselected constant load, a variable load means in said housing adapted to act in opposition to said first load means to load said housing and roll journals to an initial load equivalent to a preselected reduction on the average thickness of a strip entering the mill, means for varying said variable load on the housings and journals when the strip thickness changes from said average thickness and means preceding the work rolls adjacent the strip passline for measuring strip thickness controlling the load varying means to increase the load as the strip thickness increases above said aver-age and decreases the load as the strip thickness decreases below said average.

4. A rolling mill structure comprising work rolls on opposite sides of a strip passline receiving a strip to be reduced therebetween, journals at the ends of said work rolls, a housing carrying said journals, a first load means in said housing urging the work rolls together and adapted to load said housing and roll journals to a preselected constant load, a variable hydraulic load means in said housing adapted to act in opposition to said first load means to load said housing and roll journals to an initial load equivalent to a preselected reduction on the average thickness of a strip entering the mill, means for varying said variable load on the housings and journals when the strip thickness changes from said average thickness and means for measuring strip thickness controlling the load varying means to increase the load as the strip thickness increases above said average and decrease the load as the strip thickness decreases below said average.

5. A rolling mill structure as claimed in claim 4 wherein the means for varying the load on the housing is a servo controlled valve and the means for measuring strip thickness controls the opening and closing of said servo valve.

6. The method of rolling a strip to uniform thickness comprising the steps of:

(l) feeding a strip to be rolled to the work rolls of a rolling mill in which the work rolls are journaled in a mill housing;

(2) preloading the mill housing and the roll journals thereon with a first preselected constant load and with a variable load in opposition to the first load to provide an initial load equivalent to a preselected reduction on the average thickness of said strip;

(3) continuously measuring the thickness of the strip ahead of the work rolls; and

(4) varying the variable preload on the mill housing and roll journals to increase the load as the strip thickness increases above said average and decrease the load as the strip thickness decreases below said average.

7. A rolling mill structure as claimed in claim 3 wherein pressure means is provided at the ends of each work roll acting on and moving the journals of said work rolls transversely to the strip passline to cause the ends of said work rolls to move toward each other so as to cause the middle thereof to engage a strip being rolled as a fulcrum to provide a desired strip contour from edge to edge of said strip.

8. A rolling mill structure as claimed in claim 7 wherein the pressure means are hydraulic cylinders between each work roll journal and its adjacent back up roll journal.

References Cited UNITED STATES PATENTS 672,466 4/1901 Smith 7216 2,523,553 9/ 1950 Blain 72-16 3,024,679 3/1962 Fox 72-243 3,197,986 8/1965 Freedman et al. 72-l6 X FRANCIS S. HUSAR, Primary Examiner.

HARRISON L. HINSON, Examiner.