US2933956A

US2933956A - Automatic screwdown-control system for rod mill

Info

Publication number: US2933956A
Application number: US712222A
Authority: US
Inventors: Richard R Snow
Original assignee: United States Steel Corp
Current assignee: United States Steel Corp
Priority date: 1958-01-30
Filing date: 1958-01-30
Publication date: 1960-04-26
Anticipated expiration: 1977-04-26

Description

R. R. SNOW 2,933,956

AUTOMATIC SCREWDOWN-CONTROL SYSTEM FOR ROD MIL April 26, 1960 3 Sheets-$heet 1 Filed Jan. 30, 1958 INVENTOR.

49/66 4490 4?. SNOW April 26, 1960 R. R. SNOW 2,933,956

AUTOMATIC SCREWDOWN-CONTROL SYSTEM FOR ROD MILL Filed Jan. :50, 1958 3 Sheets-Sheet 2 Q-R l mm INVENTOR. 4/5/4440 e .s/von April 1960 R. R. SNOW 2,933,956

AUTOMATIC SCREWDOWN-CONTROL SYSTEM FOR ROD MILL Filed Jan. so, 1958 3 Sheets-Sheet 5 Izov 34 F I l I V l I I 1 T l INVENTOR. L 19/0/44 0 4. s/von United States Patent AUTOMATIC SCREWDOWN-CONTROL SYSTEM FOR ROD MILL Application January 30, 1958, Serial No. 712,222 3 Claims. (Cl. 80-56) This invention relates to mills for hot rolling a p1urality of billets simultaneously, such as those used in converting billets to wire rod. In particular, it concerns a system for adjusting the mill screwdowns in accordance with the particular passes of the mill in which billets are actually present.

In hot-rolling billets into wire rod, a roll setting appropriate for the conditionin which all the mill passes are occupied by billets will not be proper if some of the passes are empty. That is to say, if the mill screws are properly set for rolling four billets simultaneously, for example, and one billet is dropped because of a cobble or any other reason, the resulting reduction of the roll spring will cause the remaining billets to be overreduced. This necessitates a slight backing off of the screws to cause the mill to effect only the proper reduction and no more. Such compensating adjustment is customarily made manually but is too slow for rapid changes and is therefore made only when a change continues for a substantial period. It is the object of my invention to provide automatic means responsive to the presence of billets in the mill passes, for effecting this adjustment.

In a present preferred embodiment of the invention, I employ radiation-responsive means directed at the paths of heated billets traversing the several passes of a mill stand. I also provide manually settable means effective when operative, to bring the mill screws to predetermined positions through operation of a conventional screwdown motor and controller. Selector relays controlled by the radiation-responsive means in accord with the billetstraversing the mill, serve to connect the proper manually settable means in circuit to operate the screwdownmotor controller to effect the necessary adjustment.

A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanying drawings illustrating the present preferred embodiment. In the drawings:

Figure l is a diagrammatic side elevation of a mill showing the radiation-responsive means in position thereon;

Figure 2 is an end elevation corresponding to Figure 1;

Figure 3 is a diagrammatic showing of the relationship between the radiation-responsive means, the manually settable means and the selector relays as a group;

Figure 4 is a circuit diagram of the radiation-responsive means and the selector relays; and

Figure 5 is a circuit diagram of the controller for one screwdown, along with the manually settable means.

Referring now in detail to the drawings and, for the present, particularly to Figures 1 and 2, a stand of a continuous rod-mill, preferably the first stand thereof, includes rolls 11 journaled in spaced housings 12 provided with screws 13 for adjusting the roll setting. Motors 14 mounted on brackets 15 drive the screws individually. Rolls 11 have several matching pairs of grooves 16 therein, each cooperating pair defining a pass 2,933,956 Patented Apr. 26, 1960 for reducing a billet. The billets in the several passes illustrated are designated 17, 18, 19 and 20. Entry and exit guides 21 and 22 direct the billets into and out of the'several passes.

A post 23 adjacent stand 10 but spaced to one side thereof has a lateral arm 24 at its upper end to which is pivoted a tiltable arm 25. Arm 25 is normally disposed in the horizontal position shown in solid lines in Figure l, overhanging the pass line between the rolls 11. It may, however, be uptilted to the chain-line position so as to be out of the

wa Sensing devices

26, 27, 28, 29 responsive to infra-red radiation are spaced along arm 25 in locations such that, when the arm is in the illustrated position, the devices will receive radiation from heated billets traversing the passes of the mill stand 10. Devices such as 26 are well known per se and are available commercially. They are provided with contacts 30, 31, 32 and 33, respectively (see Figure 4) which are normally open but are closed when infra-red radiation of predetermined intensity impinges thereon.

Figure 3 shows the control system of my invention schematically. For each screwdown of the stand 10, I provide a plurality of manually settable devices, e.g., otentiometers, 34, one potentiometer of each set corresponding to a predetermined condition in respect to the presence of billets in the several mill passes or their absence therefrom, as illustrated in the chart at the right of Figure 3. More specifically, the uppermost potentiometers 34 are manually preset to bring about the proper setting of the two mill screws (through means to be described hereafter) for rolling billets in all four passes simultaneously to the desired size, as indicated in the chart by blocks 35. Similarly, the next potentiometers in the row are set for the roll setting appropriate for rolling three billets when the second one from the left has been dropped, as shown at 36. The remaining potentiometers are set for the other conditions as indicated respectively, by blocks 37, 38, 39 and 40, viz., third billet dropped, first billet dropped, fourth billet dropped and no billets in the mill.

As will be further explained by reference to Figure 4, the existence of one or the other of the conditions illustrated schematically in Figure 3 at 35, 36, 37, 38, 39 and 40, will bring the corresponding otentiometers in to play to effect a setting of each of the mill screws appropriate to the condition observed by devices 26 through 29. This is accomplished by a selector S, the circuit of which is shown in Figure 4, and a controller shown in Figure 5, actuated by the selector. Referring now to Figure 4, the contacts 30, 31, 32 and 33 of

devices

26, 27, 28 and 29, when closed, energize relays 41, 42, 43 and 44, respectively. Each of these relays actuates a plurality of contacts 41a, 41b, 41c, 41d and 41e, for example, some normally open and some normally closed as shown.

The several contacts of the relays 41, 42, 43 and 44 constitute interlocks controlling condition-

selector relays

45, 46, 47, 48 and 49. The arrangement of the contacts is such that when all of relays 41, 42, 43 and 44 are energized, relay 45 will be energized but the circuits for

relays

46, 47, 48 and 49 will be open. Similarly, when relay 42 is deenergized, relays 41, 43 and 44 remaining energized, the circuit for relay 46 will be closed but the circuits of

relays

45, 47, 48 and 49 will be open. The remaining circuits for

relays

47, 48 and 49 are similar. The overall result is that one and only one of

relays

45, 46, 47, 48 and 49 will be energized for each of the conditions illustrated at 35, 36, 37, 38 and 39 of Figure 3.

Each of

relays

45, 46, 47, 48 and 49 has a normally closed contact (e.g., 45a) and a normally open contact (e.g., 45b). The normally closed contacts of all the tive to produce the. desired adjustment.

. apparent that the connection triode 52 will cause a' screw adjustment governed by the relays are connected in series with a relay 50." Thus,

called into play is amplified and applied to the grid of a second amplifier triode. 53. The resulting output of the latter energizes a difierential relay,54. This relay has. two normally opencontacts 54a and S4band func tions to close 54a on an increase in current through triod'e 53 and contact 54b on a decrease in such current.

' Contacts 54a and 54b control a reversing contactor panel for one of the screwdown motors'14, causing upward or downward movement of the screw as called for by the setting'of thepotentiometer which is connected to triode 52.

Balancing potentiometers

55 and 56 are operated in accordance withthefscrew movement efiecjustment is completed, these otentiometers red'uceflthe voltages on the

grids oftriodes

52 and 53 to values such that no current fiows through relay 54. It will thus be.

existing setting of that potentiometer.

The controller 51 is for one screwdown motor. A similar controller is provided for the other motor. Duplicate contacts on relays '45, 46,v etc. like contacts 45b, 46b, etc. control the connection of potentiometers'34 for the other screw to the second control system.

The'invention greatly reduces the rod-size variations previously occurring and minimizes the number of cobbles resulting from buckling by automatically compensating the setting of, the rolls of the first stand of a rod The voltage.

of any potentiometer 34 to' mill in accord with the number of billetsactually'in the mill. As a result, the invention produces an increased 7 yield anda better quality of product.

Although I have disclosed hereinthe preferred embodiment of my invention,;I;intend to cover as well any change or modification therein which may be made withoutdeparting from the'spirit and scope of the invention.

I claim: 7 .1. In a rollingmillxincludinga pairlof cooperating rolls having a pluralityof sets of matching. grooves. de-

' fining several passes for reducing a plurality of billets simultaneously, roll-adjusting screws, a motor driying one of the screws and a controller for said motor, the combination therewith of a plurality of manually settable means adapted, respectively, to causethe controller to adjust the rolls to difierent settings, depending on which sets of grooves are occupied. bybillets undergoing reduction at a given time, and means responsive tto'the presence of billets: in said sets of grooves, respectivel a. effective to connect a selected one 02 said manually settable means to said controller." I a 2. The combination defined ii -claim- 1, characterizedby said :responsive means including ;,a.plurality' of relays 7 affected by radiation from hot bodies, each of said re.-

lays being positioned to -receive:.radiation from a billet in one of said passes. i

3. The combination defined in claim 2,. characterized pivoted'ther'eto' adapted to extend as a cantilever beam by a post standing. adjacent: said mill having an over the mill, said radiation relays being spaced alongsaid arm.

References Cited in the filefof this patent, UNITED, STATES PATENTS Shayne et al. Jan. 18, 1944 1,813,539 Hurley July 7; 1931- '1,951,426 Littler Mar. 20,v 1934 2,289,410 Dahlstrom July 14,,l942. 2,339,359