US3506439A - Regulating the feeding of metal particles to the roll gap of a rolling mill - Google Patents

Description

Apnl 14, 1970 K. CLAUS ET AL 3,506,439

REGULATING THE FEEDING OF METAL PARTICLES TO THE ROLL GAP OF A ROLLING MILL Filed May 11. 1966 3 Sheets-Sheet l Filed May 11, 1966 April 14, 1970 K. CLAUS ET AL 3,506,439

REGULATING THE FEEDING OF METAL PARTICLES TO THE ROLL GAP OF A ROLLING MILL 3 Sheets-Sheet 2 April 14, 1970 K. CLAUS ET AL 3,506,439

REGULATING THE FEEDING OF METAL PARTICLES TO THE ROLL GAP OF A ROLLING MILL Filed May 11, 1966 3 Sheets-Sheet :5

United States Patent U.S. Cl. 75-226 8 Claims ABSTRACT OF THE DISCLOSURE A process for regulating the feeding of metal particles to the roll gap of a rolling mill, which metal particles have been heated to the rolling temperature by a furnace. The height of the metal particles in a container directly above and exiting to the roll gap is sensed, this sensed height is compared to a predetermined height which will give the metal particles a residence time in the container which is approximately constant and short enough to insure that the metal particles do not cool unevenly, and then the predetermined height is maintained by controlling the rate of supply and output of the particles to and from the roll gap in dependence upon variation from the predetermined height of the metal particles in the container. Furthermore, the predetermined height can be maintained by discharging metal particles into the container at a rate greater than the rolling mill throughput, and deflecting the excess portion of the particles before they reach the container.

Regulating the supply of metal particles to a rolling mill is very important, in order to obtain a satisfactory rolled product, particularly when the metal particles are rolled in a hot condition, as in the wrought-iron process for example. In this case it is important that the waiting time of the metal particles in front of the roll gap should be kept as short as possible, in order that the particles may not cool down excessively and unevenly. The risk of uneven cooling is present above all at the marginal regions of the roll gap, because an increased loss of heat of the particles to the exterior is there effected. Even when rolling cold metal particles, however, it is desirable, for the maintenance of a steady flow of material over the roll gap, to control the supply of particles with precision, in order that the conditions for the engaging of the metal particles in the roll gap may always remain the same. Furthermore, kinetic energy that is imparted to the particles may be maintained, and be come operative in the gripping operation.

The object of the invention is to provide a method of regulating the supply of metal particles to the roll gap, and devices for carrying out the method, which will enable the method to be operated continuously. In this way the waiting time of the metal particles above the roll gap is to be approximately constant, and to be as short as possible, in order that the rolled product may be improved, and that the economy of operation of the rolling-mill plant may be enhanced.

According to the invention, the new method of regulation is distinguished by the feature that the height of filling of the metal particles above the roll gap forms a regulating magnitude for the devices that determine the flow of the metal particles. Owing to the fact that all the devices participating in the flow of the metal particles are adjusted to (or depth) of filling above the roll gap,

3,506,439 Patented Apr. 14, 1970 ice a uniform flow of particles to the roll gap admits of being maintained, so that the particles are prevented from caking together in consequence for instance, of an excessive height of pouring above the roll gap, and in addition to this the power consumption of the rolling mill is reduced to a minimum, since the most advantageous temperature requisite for the welding of the metal particles can be maintained.

These advantages are of particular importance in rolling-mill plant that is designed for the production of strips or sections which aim, in their method of working, at a welding of the metal particles. In this way, for instance, the treatment of aluminium may be effected in air, whilst other metals, such as steel, have to be worked under a protective gas.

Advantageously the height of filling: forms a measuring magnitude for the regulating means of the devices in the plant that determine the flow of material. In plant with the furnace just in front of the rolling mill for the metal particles, the furnace is preferably charged with a quantity of particles dosed to correspond exactly to the consumption of the rolling mill. In cases in which the regulating of the supply of particles to the furnace proves to be too sluggish or too difficult for regulating the supply of particles to the roll gap, it is advisable to influence the roll speed in dependence upon the height of filling above the roll gap. It may also prove advantageous to regulate both the amount passing through the furnace and the amount passing through the rolling mill jointly in dependence upon the height of filling. This is an advantage more particularly when the range of regulation, both of the amount passing through the furnace and of the amount passing through the rolling mill, is to be kept as small as possible.

A direct influencing of the height of filling above the roll gap also admits of being advantageously obtained when the discharge from the furnace is influenced by means of a regulating device. In this case a portion of the flow of particles, which is too much for keeping the height of filling constant, is deflected from the flow of particles on its way between the furnace and the rolling mill. A regulating of the furnace discharge is appropriate self above all where the work is to be done with as constant a rolling speed as possible, and where an immediate influencing of the height of filling of the metal particles above the roll gap is nevertheless desirable. In this way it is possible, with an increased furnace discharge occurring owing to an uneven flow of material in the furnace, such as would render necessary a change going beyond the range of regulation provided for the amount passing through the rolling mill, to maintain the height of filling of the roll gap.

In the simplest case the influencing of the individual regulating devices can be eifected by an observer, who follows the state of filling above the roll gap either directly or by means of a telescopic device. In a further development of the invention, the measuring of the height of filling of the metal particles above the roll gap, which serves as a measuring magnitude for the individual regulating devices of the plant, is carried out with a measuring device consisting of radioactive isotopes and an indicator tube or Geiger counter. The measuring device may however, in an equally advantageous manner, be founded upon a photo-electric basis. It is equally advantageous to utilise electrical conductivity or electrical capacity for measuring the state of filling. When employing radioactive isotopes or photo-electric cells, the radiator, such as the radio-active isotope, or light, is arranged upon one side of the lateral boundary of the roll gap, and the receiver, such as the Geiger counter or photo-electric cell, on the other side. A particularly simple arrangement of radiator and receiver is obtained if they are provided on the lateral boundary walls of the devices for feeding the metal particles to the roll gap.

In installations in which the rolling mill is preceded by pusher-type or continuous-heating furnace for heating the metal particles, the charging device for the furnace is combined with a closing appliance influencing the quantity of particles. As a dosing appliance an adjustable shakerloader may advantageously be employed, which at the same time effects the charging of the pusher-type furnace. The dosing device may alternatively be constructed as a dosing belt balance. These appliances likewise admit of being put in appropriately for the direct feeding of the metal particles to the roll gap. In this case it is a question of installations which are combined with means for producing the metal particles, the metal particles being formed from a liquid metal melt and supplied to the roll gap in the same heat.

Furthermore these charging appliances may advantageously precede rolling mills in which the metal particles are united in a cold state, to a green strip for example, which is then subjected to a sintering operation.

In plant with a pusher-type furnace preceding the rolling mill, and regulation of the flow of particles leaving the furnace outlet, a by-passing device for the flow of particles is provided in a further development of the invention. If a feeding shaft surrounding the flow of particles is arranged between the furnace outlet and the rolling mill, a =by-passing device is obtained in a simple manner, by providing the feeding shaft with a lateral aperture, which co-operates with a flap valve, or a wedge slidable transversely to the direction of fall of the metal particles, in such a way that when the flap valve is rocked in, or the wedge is slid into the flow of particles, the particles wholly or partly issue from the lateral aperture of the feeding shaft. Instead of a wedge or flap valve, there may be employed for deflecting a portion of the flow of particles a rockable or slidable off-take funnel, into the upper aperture of which a supply pipe coming from the furnace opens, and the lower aperture of which can be brought into operative communication alternatively with the feeding means for the rolling mill or with a deflecting channel. In order to obviate losses of heat, the region between the end, adjacent to the deflecting funnel, of the feed pipe coming from the furnace, and the feeding means for the rolling mill, and also the deflecting channel, may be surrounded by heat-checking walls.

The use of such a deflecting funnel has the advantage that its actuation cannot be blocked by the metal particles.

Some embodiments of the invention are illustrated in the accompanying drawings, in which:

FIGURE 1 is a diagrammatic sketch of plant for the production of sheet-metal strips from heated metal particles;

FIGURE 2 shows a dosing or metering means, constructed as a dosing belt balance, preceding a rotary tubular furnace, together with an appliance for regulating the flow of particles arranged between the furnace outlet and the rolling mill;

FIGURES 3, 4 and 5 show various modifications of the means for regulating the flow of particles in the region the furnace outlet and the rolling mill;

FIGURE 6 shows a section on the line VIVI in FIG- URE 4; and

FIGURE 7 shows a section on the line VII-VII in FIGURE 5.

In the plant shown in FIGURE 1, for the production of strips from heated metal particles, B denotes a storage bunker for the metal particles D. From this bunker B the metal particles are supplied to a conveyor F, which passes them on into a container Z. From this container Z the metal particles are supplied to a dosing shaking trough R, and from there to a further shaking trough R0, which charges the furnace O. In the furnace O the metal particles are heated to rolling temperature, and supplied at the furnace outlet 00, to the rolls W, Where they are consolidated to a compact strip Ba. The strip Ba is then wound into a coil Bu.

Now in order that a strip of constant quality may be obtained, it is necessary that the metal particles should be supplied to the roll gap at a constant temperature, that their waiting time in front of the roll gap should be kept constant, and that their height of filling in the feed hopper above the roll gap should be kept as small as possible, in order that their loss of heat to the exterior may remain small owing to the shortness of the waiting time connected herewith before the roll gap. In order to keep the height of filling of the metal particles constant above the roll gap of the rolling mill W, this height is adopted as the regulating magnitude for the devices that determine the flow of the metal particles.

This purpose is served by the regulating device Re, to which the desired height of filling Fs is fed. Now if the actual height of filling Fz', measured above the roll gap, differs from the desired height of filling Fs, first the speed of revolution Vm of the motor of the rolling mill W is influenced in such a way that by the greater or smaller rolling speed the actual filling height is restored to the desired filling height with constant feeding of the metal particles from the furnace outlet On. Now as soon as a definite speed range of the motor M for the regulating has been exhausted, the feeding of the metal particles to the furnace is introduced into the regulating means. Here the desired through-put quantity SD participating in the regulating of the dosing means D0 is altered by the value K, which has been determined from the fullness-regulating means Re. Since this change in the metal particles to be supplied to the furnace cannot work out directly at the furnace outlet, there is provided, between the furnace outlet and the rolling mill, a regulating device Rm, which influences the flow of material immediately before the rolling mill, and deflects a portion Pt of the metal particles, which corresponds to the amount A determined by the regulating device Re. The measuring device arranged at the feeding funnel T for the filling-level height of the metal particles is denoted by Me and Ms, Ms denoting, in the case of photo-electric or radio-active measurement, the emitter, and Me the receiver, which in FIGURE 1 are located one behind the other on the lateral boundary walls of the feeding funnel T.

The quantity of particles supplied from the furnace outlet to the rolling mill is kept greater than would be required for the regulating range of the motor for the rolling mill, so as to be able to cope reliably with relatively large fluctuations in the supply of particles.

The dosing appliance for supplying the metal particles to the furnace consists, in the plant illustrated in FIG- URE 1, of a shaking trough R, the drive An of which yields, correspondingly to the initiated regulating value Dk, which is adjusted from the difference between the desired throughput SD and the actual through-put Di measured by the measuring device DM. In the plant shown in FIGURE 1, the charging of the container is also adjustable, this likewise being by way of the filling height thereof, which is fed by the measuring instrument Mb into the charge-regulator Br. By the ascertained difference for the desired filling height Bs fed in the bunker discharge Pa is influenced correspondingly to the ascertained regulating value Br.

According to FIGURE 2, the dosing of the flow of particles 5 to the furnace 1 is effected by the dosing belt balance 18, which co-operates with a vibration trou'gh 12. The vibration trough 12' serves in this case exclusively for the charging of the rotary tubular furnace 1.

The dosing belt balance 18 consists of a conveyor belt 19, which passes round two guide pulleys 20 and 21. The pulley 20 is positively driven. Between the two supporting rollers 22 is arranged a roller 24, co-operating with a balance 23. The roller 24 is loaded with the weight of the flow of particles between the two supporting rollers 22, which is continuously determined by the balance 23,

and fed into the regulator Ra. At the same time the speed of the belt continuously ascertained by the measuring roller 25, is fed into the regulator. Since the weight of the flow of particles relates to the measured distance between the two supporting rollers 22, the product of the weight measured by the balance 23 and the speed measured by the roller 25 yields the weight per unit of time, which is to remain constant, and is fed into the regulator as the desired value S. If the measured actual value does not agree with the desired value, the speed of the conveyor belt 19 is appropriately modified by adjusting the speed of the drive. The regulating conductor leading from the regulator to the drive is marked A, and the container that charges the belt conveyor 19 is marked 11.

In the supply shaft 17, arranged between the furnace outlet 7 and the pair of rolls 9, and surrounding the flow of particles is provided a lateral aperture 13 or 13 which co-operates with a flap value 14 in FIGURE 2 or with a sliding wedge 14 in FIGURE 3, in such a way that when the valve 14 is rocked or the wedge 14 is slid into the flow of particles 5, the latter issues wholly or partly out of the lateral aperture 13 or 13' of the feed shaft. The laterally issuing flow of particles 5" is discharged by way of a by-pass 16, right away from the rolling mill.

In the apparatus illustrated in FIGURE 4, for regulating the flow of particles between the furnace outlet 26 and the rolling mill 28, the end 27a of the first portion of the feed pipe 27 opens into a transversely slidable deflecting funnel 29. The upper aperture 30 of the deflecting funnel is oval or oblong in shape, so that the deflecting funnel, while still received all the particles that come down the feed pipe 27, can be displaced so far to one side that its lower outlet aperture 31 passes out of range of the lower feed-pipe section 27', and assumes a position with its outlet aperture above the deflecting channel 32. This second position of the funnel is represented in discontinuous lines. The displacement of the deflecting funnel is effected by means of a rod 33, which projects through a fireproof wall 34.

The deflecting funnel has, on its long sides, bearing surfaces 35, shown in section in FIGURE 6, which bear upon suitably constructed bearing surfaces 36. According to the position of the deflecting funnel, the flow of particles 5' is either guided entirely into the lower part 27' of the feed pipe, and is there supplied to the rolls 28, which work up the particles into the final product 37, or else only a part thereof is supplied to the lower portion 27 of the feed pipe, and the rest is guided into the deflection channel 32, in order to keep the particle height 38 above the roll gap 39 constant. Upon a brief interruption of the rolling mill, the deflecting funnel is brought into the position represented by discontinuous lines, so that the flow of particles is turned completely into the deflecting channel. Thus the furnace need not be stopped, on the operation can be immediately resumed as soon as the interruption at the rolling mill is removed.

In FIGURES 5 and 7 the deflecting funnel, 29 is suspended by means of pivots 40 in the thermally insulating wall 34. The upper aperture 30 of the receiving funnel 29 can thus be made smaller. In other respects the method of working is the same as with the arrangement of the deflecting funnel 29 shown in FIGURES 4 and 6.

We claim:

1. A method of regulating the supply of metal particles to the roll gap of a rolling mill for the continuous production of strips from said particles which have been heated to the rolling temperature by a furnace, comprising the steps of sensing the filling height of the metal particles in a container directly above and exiting to said roll gap; comparing the sensed height to a predetermined height which will give a metal residence time in the container which is approximately constant and short enough to insure that the metal particles do not cool unevenly; and maintaining said predetermined height by controlling the furance through-put and the rolling mill through-put jointly in dependence upon variation from the predetermined height of the metal particles in the container. 1

2. A method as claimed in claim '1 wherein the furnace through-put control is accomplished by measuring and controlling the quantities of the metal particles entering the furnace by means of a dosing device located at the entry end of the furnace.

3. A method as claimed in claim 1 wherein the rolling mill through-put control is accomplished by varying the rolling speed of the rolling mill.

'4. A method as claimed in claim 1 wherein said sensing step is carried out by means of radio-active isotopes and a Geiger counter.

5. A method as claimed in claim 1 wherein said sensing step is carried out photo-electrically.

:6. A method as claimed in claim 1 wherein said sensing step is carried out on the basis of electrical conductivity.

7. A method as claimed in claim 1 wherein said sensing step is carried out on the basis of electrical capacity.

8. A method of regulating the supply of metal par ticles to the roll gap of a rolling mill for the continuous production of strips from said particles which have been heated to the rolling temperature by a furnace, comprising the steps of sensing the filling height of the metal particles in a container directly above and exiting to said roll gap; comparing the sensed height to a predetermined height which will give a metal residence time in the container which is approximately constant and short enough to insure that the metal particles do not cool unevenly; and maintaining said predetermined height by providing a greater rate of discharge of metal particles from the furnace than the rolling mill through-put requires, and deflecting the excess portion of the particles on the way from the furnace to the rolling mill in dependence upon variation of the filling height from the predetermined height of the metal particles in the container.

References Cited UNITED STATES PATENTS 2,977,631 4/1961 Komarek 189 3,245,114 4/1966 Ready l89 FOREIGN PATENTS 1,029,277 4/ 1958 Germany.

CARL D. QUARFORTH, Primary Examiner A. J. STEIN-ER, Assistant Examiner US. Cl. X.'R. 189; 2644O

Images