US3501733A - Multiple rheostat assembly - Google Patents

Description

March 17, 1970 v cs. E. LEMON 3,501,733

MULT IPLE RHEOS TAT AS SEMBLY Filed June 12, 1968 2 Sheets-Sheet 1 INVENTQR. GEORGE E. LEMON F I G. 7

AGENT .March 17, 1970 I ,G. E. LEMON 3,501,733

MULTIPLE RHEOSTAT ASSEMBLY Filed June 12, 1968 2 Sheets-Sheet 2 27A 30 I 29A INVENTOR.

GEORGE E. LEMON BY AGENT United States Patent 3,501,733 MULTIPLE RHEOSTAT ASSEMBLY George E. Lemon, 286 Lora Ave., Youngstown, Ohio 44504 Filed June 12, 1968, Ser. No. 736,453 Int. Cl. H01c /00 US. Cl. 338-131 9 Claims ABSTRACT OF THE DISCLOSURE A multiple rheostat assembly for controlling a number of related functions, such as the speeds of the drive rolls of a strip rolling mill. A number of horizontal frames each having a contact blade pivotally connected to one end of the frame are vertically stacked. Associated with each horizontal frame is a cylindrical drum having a plurality of resistor elements of differing values. The drums are positioned so that the resistor element on the bottom of the drum contacts the blade of the corresponding horizontal frame. The drums are carried by a vertical frame which slides on the side rails of the horizontal frame and the drums may be simultaneously rotated to bring different value resistor elements into contact with the corresponding blades.

This invention relates to a multiple rheostat and more particularly to a multiple rheostat in which each of the rheostats is proportional to the others and in which the proportions may be varied. Such a multiple rheostat is of particular value in the controlling of the finishing stands of strip rolling mills.

In the production of strip from steel billets, there are provided several (usually four) roughing stands which receive heated billets from a furnace and which effect an initial reduction in thickness of the billet. The resulting slab or bar is then passed to the finishing mill train, which may, for example, consist of six fourhigh mill stands, each of which effects a further reduction in thickness of the slab, the result being a strip of precisely controlled and uniform thickness or gage. It is readily apparent that, in order to prevent cobbles or tearing of the strip during the rolling operation, the individual stands must be run at successively higher speeds from the first or entrance stand to the last or exit stand. Further, these speeds vary with the thickness of the incoming slabs, the amount of reduction effected by each stand, and the dc sired exit gage. In order to produce strip having uniform physical properties it is necessary to maintain the temperature of the strip within certain limits. This is accomplished by varying the total length of time the strip is passing through the mill. Thus, if, for example, an incoming slab is somewhat cooler than desired, it is necessary to shorten the rolling time by increasing the speeds of all the stands of the rolling mill.

Presently employed speed control systems are such that the speed of each stand is adjusted independently of the remaining stands thus requiring an appreciable length of time for the adjusting of the speeds of the entire finishing mill and requiring considerable computation by the operator to determine the correct speed of each stand thus increasing the possibility of error.

It is the primary object of the present invention to provide an improved multiple rheostat assembly which allows simultaneous, proportional control of the rheostats. A further object of the invention is the provision of such a multiple rheostat assembly which permits simultaneously vemier adjustment of the rheostats without altering the ratios between the rheostats. Another object of my invention is the provision of a multiple rheostat in which the ratios between the rheostats may be varied. It is also an object of my invention to provide a multiple 3,501,733 Patented Mar. 17, 1970 rheostat which may be used in the control of the speed of the finishing stands of a strip rolling mill.

The above and other objects and advantages of my invention will become apparent upon consideration of the following specification and the accompanying drawing wherein there is shown a preferred embodiment of my invention.

In the drawing:

FIGURE 1 is a plan view of the device of my invention;

FIGURE 2 is a front elevational view of the device of FIGURE 1;

FIGURE 3 is a fragmentary, longitudinal sectional view, taken along the line III'III of FIGURE 1;

FIGURE 4 is a fragmentary, transverse sectional view, taken along the line IV -IV of FIGURE 2;

FIGURE 5 is a plan view, on an enlarged scale and partially in section, of the resistor drum used in the device of FIGURE 1;

FIGURE 6 is a fragmentary, transverse sectional view, taken along the line VIVI of FIGURE 5; and

FIGURE 7 is a fragmentary, transverse sectional view, taken along the line VIIVII of FIGURE 1.

I provide a plurality of horizontal frames 10A-Feach having a front rail .11, rear rail 12, and side rails 13. The frames 10A-F are supported, in uniform spacing, by vertical rails 14. The side rails 13 which are conductive are insulated from the front and rear rails 11 and 12 and from the vertical rails 14 by insulating pads 15 so that each of the side rails 13 is electrically separated from the remainder of the frame. Each of the side rails 13 is also provided with a terminal 16. Pivotally mounted on a vertical rod 17 carried by projections 12 of the rear rails 12 are a plurality of bars 18A-F, one for each of the frames -10AF. Each of the bars 18 has a rigid base 19, preferably of an insulating material, and a bladelike conductor 20 on its upper surface. A terminal 21 is provided for each of the conductor blades 20. The bars 18 are supported at their rear ends by the projections 12' and spacers 22 on the rod 17 and at their front ends by the rails 11 in such manner that the upper surfaces of the blades 20 are parallel to the planes defined by the side rails \13. Each of the bars 18A- F is provided with an upwardly extending lever 18A'- to permit the bar to be moved from the top of the stacked horizontal frames.

Slideably mounted on the side rails 13 of the fixed frame assembly is a vertical frame 23 consisting of a pair of end plates 24 to which are fastened shoes 25A-F which slide, respectively, on the rails 13A-F and which have upwardly projecting portions 25. Corresponding pairs of the shoes 25 are joined to one another by pairs of side plates 26. The shoes are insulated from the end plates 24 and side plates 26. A resistor drum 27 (to be more fully described hereinafter) has its end shafts 28, 29 journaled in the projections 25 of each of the pairs of shoes 25A-F. Each of the shafts 29A-F is provided with suitable pulleys and belts 30 or gears so that all of the shafts 29A-F may be rotated simultaneously. The shaft 29A extends beyond the shoe 25A and is provided with a wheel 31' to permit the operator to rotate the resistor drum 27A and, through the belt 30, the drums 27B-F.

Each of the drums 27 consists of a cylindrical, nonconductive body portion 32 having a plurality of longitudinal slots 32 uniformly spaced on its cylindrical outer surface. A resistor element 33 is provided in each of the slots 32' and has its ends connected to disks 34 and 34' which are, in turn, connnected to the shafts 28 and 29. The drums 27 are so positioned that the resistor element 33 in the bottom slot 32 of the drum contacts the blade 20 of the corresponding bar 18. The resistor elements 33 3 are, preferably, arranged in a uniform order of varying resistivity.

When the device of my invention is used to control the speed of a strip rolling mill, one horizontal frame and associated resistor drum is used in conjunction with each of the stands of the mill, the rheostat being connected in place of the rheostat normally provided in the operators pulpit and connected by the terminals 16 and the terminal 21 to the drive motor control circuit.

Suitable markings 35 may be provided on the front rail 11 of the uppermost horizontal frame A for positioning the levers 18A'F and, consequently, the bars 18AF. Likewise markings 36 may be provided on the side rails 13 of the frame 10A for positioning the vertical frame 23 and the resistor drums 27.

In the embodiment shown, the markings 35 and 36 are specifically designed to facilitate the use of my device in controlling the finishing stands of a strip rolling mill. The markings 35 indicate the ratio of the speeds of the drive rolls of the stands. It has been found that a preferred ratio for a six stand finishing mill is 3210;:30: 40:45 and the levers 18A are positioned according to this ratio. If it should be necessary to operate the mill with less than the normal six stands, the bars associated with the stands being operated may be repositioned so as to provide the optimum speed ratio in that situation.

The marking 36, in the illustrated embodiment, indicate the exit gages of the strip being produced by the mill and these markings are so positioned that, when, for example, the vertical frame is in registry with the .140 markings, the speeds of the stands of the mill will be the optimum ones for rolling strip having this finish gage. If it becomes necessary to increase or decrease the speed of the rolling operation due to variation in the temperature of the incoming slab or to other factors, the speed can be raised or lowered by rotating the drums 27 to bring a resistor element 33 of greater or less resistance per unit of length into contact with the blade 20 without disturbing the gage related setting of the vertical frame 23 or the speed ratio determined by the positions of the bars 18. Suitable markings may be provided on the wheel 31 to indicate the percentage increase or decrease from normal speed resulting from the selection of a dilferent resistor element.

While the invention has been described with particular reference to the control of the speed of strip rolling mill finishing stands it will be readily apparent that the device of my invention is not limited to such use and may advantageously be employed in any situation where it is desired to control a number of related operations by means of rheostats operating in a ratio, especially where it is desired to vary the ratio, and where it is also desired to allow variation without disturbing the setting of one of the primary variables. It will also be apparent that while the bars 18 and contact blades 20 are shown as being straight, they may be curved if desired to provide different ratios. Further, the number of horizontal frames provided and, therefore, the number of operations controlled may also be varied.

As these and other changes may be made in and to the illustrated embodiment of my invention without departing from the spirit thereof, reference should be had to the appended claims in determining the true scope of my invention.

I claim:

1. A multiple rheostat assembly, comprising:

( 1) a plurality of horizontal frames in spaced, vertical relationship to one another, each frame havin (a) a front rail, I

(b) a rear rail,

(0) a pair of conductive side rails, said side rails being insulated from said front and rear rails, and

(d) a contact bar, said bar being connected to said rear rail, extending to said front rail, and insulated from said front and rear rails;

(2) a vertical frame, having (a) a pair of vertically extending end plates,

(b) a plurality of pairs of conductive shoes, a pair of shoes being provided for each of said horizontal frames, one shoe of each pair being slideably received on one of said side rails'and secured to but insulated from one of said end plates, the other of said shoes being slideably received on the other of said side rails and secured to but insulated from the other of said end plates, and

(c) side plates joining but insulated from the shoes of each of said pairs of shoes; and

(3) a plurality of resistance elements, at least one resistance element extending between said electrically connected to the shoes of each of said pairs of shoes, and being in point contact with the contact bar of the horizontal frame on which said shoes are received.

2. Apparatus according'to claim 1 further characterized in that said contact bars are pivotally connected to said rear rails.

3. Apparatus according to claim 2 further characterized in that the pivot points of said contact bars have a common vertical axis.

4. Apparatus according to claim 3 further including a vertically extending lever secured to the forward end of each of said contact bars, said levers terminating in a common plane adjacent the upper surface of the assembly.

5. Apparatus according to claim 1 further including a cylindrical drum rotatably carried by each of said pairs of shoes, extending between said pair of shoes, a plurality of said resistance elements being mounted in longitudinal slots on the surface of said drum, the arrangement being such that said drum may be rotated about its longitudinal axis to bring different ones of said resistance elements into contact with said contact bar.

6. Apparatus according to claim 5 further including means to simultaneously rotate each of said drums.

7. Apparatus according to claim 6 further characterized in that said contact bars are pivotally connected to said rear rails.

8. Apparatus according to claim 7 further characterized in that the pivot points of said contact bars have a common vertical axis.

9. Apparatus according to claim 8 further including a vertically extending lever secured to the forward end of each of said contact bars, said levers terminating in a common plane adjacent the upper surface of the assembly.

References Cited UNITED STATES PATENTS 628,685 7/1899 Berresford 338-131 XR 3,307,133 2/1967 Wolff 338--131 XR 3,355,694- 11/196-7 Wollf 338-428 XR THOMAS J. KOZMA, Primary Examiner

Images