US2941126A - Variable time interval system - Google Patents

Description

June 1960 a. E. FRANKENFIELD 2 ,9

VARIABLE TIME INTERVAL SYSTEM Filed Feb. 25, 1954 v s SheetS-Sheat 1 INVEN TOR. B. E. FRANKENF/EL 0 June 14, 1960 a. E. FRANKENFIELD 2,941,125

VARIABLE TIME INTERVAL sysmm 3 Sheets-Sheet 2 Filed Feb. 25, 1954 PHOTO- ELECTRIC RELAY V causmvr arnn Monk R J m w mm m mm N 3 5 J M i n 5 2M mm A A m M m f wzw E w, m. flllili M w nY Y 3 m w w x m j 1 June 14, 1960 Filed Feb. 25, 1954 B. E. FRANKENFIELD VARIABLE TIME INTERVAL SYSTEM 3 Sheets-Sheet 3 :jilfi ,/j16 I I 116 I 193 I l l l Q;

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B. E. FRA NKENF/ELD HAM,

United States Patent VARIABLE TIME INTERVAL SYSTEM Bruce E. Frankenfield, Chicago, 11]., assignor to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Feb. 25, 195.4, Ser. No. 412,616

3 Claims. (Cl. 317-142) This invention relates to control systems and more particularly to a control system for delaying the initiation of one operation with respect to a preceding operation.

' In the operation of metal rolling plants provided with a furnace, a roughing mill, an intermediate mill, :1 finishing mill, a conveyor for advancing billets from the furtrace to the mill and a pusher for pushing billets from the furnace onto the conveyor, the billets are sometimes separated between the intermediate mill and the finishing mill in such a manner that alternate billets go through one series of passes of the finishing mill and the other billets go through another series of passes in the finishing mill. In the past, there has been no apparatus for automatically dispatching billets to the roughly mill so spaced that alternate billets are spaced a minimum safe distance apart and substantially no farther apart.

object of the invention is to provide a new and improved control system in which the initiation of one operation is delayed a variable period of time dependent on the duration of a preceding operation.

.Another' object of the invention is to provide new and improved billet-dispatching systems for rolling mills.

.A further object of the invention is to provide a billet-dispatching system wherein billets are fed automatically to a rolling mill as the mill needs the billets, the length of each billet to be fed to the mill being measured and the feeding of subsequent billets to the mill being controlled by the lengths of preceding billets.

A dispatching system for a rolling mill utilizing a specific embodiment of the invention may include a contwo series ofpasses to keep upwith the roughing mill tinuously operable delivery conveyor for feeding billets to a mill, a furnace, a dispatch conveyor for feeding billets from the furnace to the cleliv'e'ry conveyor and'a pusher for pushing billets from the furnace to the dispatch conveyor. "A photoelectric detecting device stops eachbillet at the delivery end of the dispatch conveyor. A

second photoelectric detector actuated by 'a partially rolled billet going therepast and positioned in the mill, works in combination with a timing system to actuate, after a predetermined time delay, the dispatch conveyor to feed a billet from the delivery end thereof to the delivery conveyor when a preceding billet is at a predetermined point in the mill, and also to actuate the pusher to feed another billet to the dispatch conveyor. In this respect, according to the invention, the timing system includes means for measuring each billet in the mill as it is rolled and for delaying the dispatch of the secondly succeeding billet in accordance with the length of the billet being measured.

A completeunderstanding of the invention may be obtained from the following detailed description, when read in conjunction with the appended drawings, in which Fig. 1 is a schematic, top plan view of an apparatus with which the-invention may be utilized;

Fig. 2 is a diagrammatic view of a portion of a control circuit of the apparatus shown in Fig. 1, including that of the invention, and.

Fig. 3 is a diagrammatic view of another portion of 2,941,126 Patented June 14, 1960 the control circuit, the top thereof fitting to the bottom of Fig. 2.

Referring now in detail to the drawings, there is shown in Fig. 1 an apparatus for dispatching billets 11 to a mill, dividing alternate billets in two paths and spacing the billets in each path a minimum distance apart regardless of variations in the lengths of the billets so that the full capacity of the mill is utilized. This apparatus includes a pusher 10 of a well known type for pushing the billets 11 of copper into and through a furnace 12, which heats the billets to a suitable temperature for billet into the furnace and pushes a heated billet out of the furnace onto a dispatch conveyor '15, which moves the heated billet endwise toward a delivery conveyor 16. As the billet nears the end of the dispatch conveyor 15, it breaks a beam of light from a projector 17 to a photo electric cell 18 of a well known type, which is responsive to blue light only, which, of course, is present in white light but not in red light from a heated billet, and the cell 18 causes the conveyor 15 to coast to a stop as the billet reaches a position clearing the beam of light at the end of the conveyor 15.

The billet is fed from the dispatch conveyor 15 to the conveyor 16, and the conveyor .16 feeds the billet through a first pass 32 of a roughing rolling mill 33. The billet drops from the first pass to a guideway 34, and the light therefrom impinges on a photoelectric cell 35 to actuate a'pusher 36 to feed the billet through a second pass 37,

which rolls the reduced billet and feeds it'to a reversing guide 38 to a third pass 39. The third pass 39 advances the billet therethrough onto a tilting shelf 40, and'the, billet actuates a photoelectric cell 41 to tip the shelf 40 by a well known mechanism (not shown) to drop the billet onto a conveyor '42, which feeds the elongated billet- ;back through a fourth .pass 43 of an intermediate mill 46 to a guide 44. The guide44 reverses the billet back to a fifth pass'45, which advances and reduces the billet to rod form and feeds it along a guide 47 to a pivotal selector guide '48.v The guide 48 may be held by a pneumatic ypiston 49 either in a position guiding the reduced billet to. a pass 50 or a pass 51 of a finishing mill 52. The

passes '50 and 51 feed to passes '53 and 54, respectively,

which advance the further reduced rods to subsequent passes 55, the increased length of the billets requiring 33 and the intermediate mill 46.

As the billet moves from the fifth pass 4 5' along the guide 47, light therefrom actuates a photoelectric cell 60, which starts the pusher 10 and the dispatch conveyor 15,

measures the billet going therepast and sets an adjustable timer 61 to control the dispatch of the secondly succeeding billet. The conveyor .15, 'after a predetermined delay, feeds another billet to the delivery conveyor 16, and the pusher 10 pushes another heated billetout of the furnace 12 onto the conveyor. 15, which feeds it to the the furnace 12 to and through the rolling mill, switches 79, and 81 (Figs. 2 and 3) are closed. The switch 80 supplies power from conductors 82 and 83 of a powerline to a control circuit. The projector 17 is energized to actuate a photoelectric relay of a well known type to keep open contacts 91, which are open when there is no power on the relay 9 0 and also when the cell 18 receives light, but are closed when the beam from the projector 17 iscut off from. the cell 18 by a billet. The switch 79 is set closed and a momentary switch 94 is held closed to actuate relays 95 and 96 to close contacts 97 and 98 in a powerline 99 to energize a motor 106,3 driving the dispatch conveyor 15 anda motor 101 actuat- 3 ing the pusher 10. The pusher (Fig. 1) pushes the first heated'billet from the furnace 12 onto the dispatch conveyor 15, and the switch 94 is held closed as the first billet, travels past thephotoelectric cell 18 to the de-v livery conveyor '1'6,"which is running continuously I feeds the billet to the first pass.

The pusher 10 and th dispatch Vance a" second billet, and asit passes thecell 18 the cell 18 is darkened to' actuate the relay" 90 to close. the

contacts 91 while the billet is going pastthecell18, and the' switch 941s released to. stop thebillet at the end of the lc'onyeyor 15. Mom'enta ry'closingof the contacts 91factuatea relay 110,. which'locks itself in through hold-I na i ec s 1, a d onte s 1 ofa-c n evc act a relay 7 3, When the switch 80 w1as closed, a relay 116 pul edi n r h ntacts 11 o ked tself. nthr'ong holding contactsfll'fijandfclos ed: contacts 119 sotlga ti,v

l yflj f a t n d, h iel y' closed? h lding cont ts'121and, contaots 122 and 123 tolock itself in and ctuate a relay 124" and fafres'ettingg time delay relay 12 5. The relay"124opene'd contacts 126, and closed contacts.1 2 7,1128 and 1291 The relay 110 also closed contacts l 35 to actuate a relay 136 toclose'contacts 137.

By" the time the secondbilletcorn es to rest on thecon veyor at the dispatching station, the time delay relay 125 has timed out to open contacts 141 to drop out the relay 124 to open the contacts 123 and 129 so thatclosing, of the contacts 137 merely sets up the circuit to the relay 113, which includes holding contacts 142. and contacts 143 for actuating themotor's 100 and 101.

tional'to the lengthfof the hillejt'sin'ce the speed at the.

billet, fixed by theffifth pass. The relay 153. medi'ately,closes 'contacts .,154, 155, l56 and 157. The. cont ts 157 actuate'af ratchet relay 15 8 to reverse the,

cond tions of contacts159 and." 160 thereof to -r everse valyecontrolling[Solenoids161 and.16 2"to, shi ft theguide 4s. T 'jren 'rsssmrts the Contacts; 159.and .160 .as it conveyor 15 then .ad-,

h istf r g w h 31 wa o d mom n r y f l V relay 194, which is a slow l e l e q 't t i "1. ts e O e n tacts .137 thereofiso that the. relay. 113remains e isjenergized each,timefbutdoesnitaflect these contacts as; itj, isldeenergi'zed, Thejclosin'g'gof contacts 15.5'an'd 56 m l e sly t rt eme s r s' im n 165 qf fi ard design and constant time delay and the delaycontrhl v n s elwe s. e 1 i bstant al? b iqt l h timer165 does so.

e mer 61." nclud asel ctor switch 171 aving esistorsj1172 connected in series/by contacts 173 anda contactor,1741 designed to engage the. contacts .173. Each ti'rneastepping relayv 175 isnergized, it moves, .the contact'or :17 4 in a. counterclockwise"direction, as viewed in. Fig. 2, to the next c ontact 173 ,throu'gha ratchet wheel 177 against the action of aspring 179. "Alat ch 178 holds the, wheel in its stePpedPQifiG i The contactor 174, conductors 181 and182, a capacitor 183, whatever of the resistors 172 that are connected,tothecapacitor, form a. resistancercapacitance. network havingfa fixed. time constant for eachsetting of the contactor 174. Thus, for

a predetermined period of.ti 1ne, depending on the setting of the contactor 174, afterthe contacts 156 areclosed to energizea transformer 185-, the resistancemapacitance.

network makes a vacuum tube 186 non-conductive, and,

after that time, makes. theltu be 186 ,conductive.,by a ing 7O thepotential on a grid187 thereof toactuatearelay188 to close contacts 189. Thecontacts 189. start astandard timer 191 which, after a predetermin'ed time, opens'the contacts 117i. andffclo'ses, contacts, 192 and, holds them in condition until f reset by openin'glof the. contacts 1 189.

4. r pickup relay. The relay 193 closes contacts 195 to actuate a relay 196 to Withdraw the latch 178 to reset the contactor 17-4 to the 0 contact 173. The relay 194 then opens contacts 197 to drop out the relays 193 and 196. The value of the resistors 172 may be such that the time of delay each imparts to the timer 61 is a multiple. of the time between pulses from the. commutator 2 22.

The opening ofthe contacts 117 does not affect the relay 116 at this time since it is locked in through thecon: tacts 118. Closure of the contacts 192 also actuates the relay 120 to close contacts 121, 1-22 and- 123, thecontacts 121 locking in;the..1 el ay.12 0 to, hold the call for a billet if one is not at the delivery endot the dispatch conveyor 15; The contacts 122 actuate the relay 124 to open the contacts 126 to drop out the relay 116 to reset the circuit for another call. The relay 124 also as e ont 1 8.. n .9. o t. u he r u 9. relay"11 3, iffa billet isfnot on the. d e-1ivery end of: the csnve sr 1 5, or ,to actuateftherelay 113, it a billet i' on the delivery end ofthelconveyor15 causing the contacts 137 to fbe, closed; When the relay. 113;,is' actuated, it opens the contacts 112, closes holding contacts142 to lock itself in, and closes contacts 143 to th'e dispatchjcon; veyor motori" and the pusher motor 101." Thed' Pa y r h le d the. bi l t 91 e d li ery. ed h w w h w st a i l; we u her, en the, conyeyor 15 bring another billet'to, the deliye f id nv T he p e 12 :5 2 .0! and theconveyor-15 are such, as conipared with the t1 q 1ir r: b. 1 t s n o heq q s ins il fiei re efitthree hat he b e 4. 11 c nv o .5 d n 1i comes to a rest at the. end-thereof; substantially he re, h -immed a ly; Pr c di bi lfitr yess fifth, Pet

As e elay;- 13 s actuated. t dro s 'q'ut th ela 19, to. rqpaout. h ela -6.- tQ we but} the relay by,v opening contacts 201. The, rel

glzed, nt a i lf s e item he ime :2.- to as v 5 m! We. fihe lllfie a k ninsabf ns all. 8 stllatesi sl n w t a e' her1 Y- 3 hrpt eel x a d; h el 36- s nst s he 113,,to stop the motors e190 and 1 1, to tiinedelaYJ hav d p d t: h r b ,1 eftf t ius u fis en eyor T ei oele n fiflis-aciuets a r m. he fii hnass each; i t be e stantpeedi n he-renne e th-1 n 1 34; es. t erelay, 1. 3 r th t time which i -.-:p opqrt to;the leng-th of; the billet, The, timer -issetfpr time abillet ot the shortest length would takein passing the-cell 60, and closes contacts, 221 at the..e nd,of; .tha t;

e; o a i et of: th or s n th, he. mer: 165 closes. the. contaotsj221 as the relay; 153-;drops;,out,

so that the, relay'175 is not actuated.-

For a billet, heavier. than. minimum (and; theretore, longer-When rolledlrthan one of minimum length), the, timer. 1.65;.c1Qscs. contacts 221 Whilethe. bi le iflLhQldi: therelay 153 111., n e, l y: 75 ispn sed thr ugh. a; commutator222 driven by a constant speed moton1223, energized through contacts 224, The numbenof is proportional to theexcess-lengthof theghillet ovengthe, minimum, such a billetv actuating the. relays, 151 and; 153.; longer than one of minimum length. The;timer-.161v has. already ..actuated,the timer "191; to. dispatch the. next billet and-has been reset: before. the;timer. 165. closes the, con-j tacts 221 sothat the timer 61- istbeingtset forstheseconds oralternate billet behind that actuating- -thecel1 .60.

'On each pulse of the relay 175, it stepsa-nother re sist'or 172 into the resistance-capacitance networln of the'timer 61 to increase the time delay beforetherelays. ssets. *9. tive he. sane-" eer silcceeding billet will be a minimum distance behind the billet energizing the cell 60. The set-ting of the relay 191' is such as to keep a billet secondly succeeding one of minimum length just the minimum distance behind that billet of minimum length, and the time delay of the timer 61 is always added to the time delay of the timer 191,.the delay of the timer 61 being zero when the coutactor 174 engages the number contact 173.

Operation Assuming one billet to be approaching the fifth pass 45 and another to have arrived at the delivery end of the conveyor 15, the latter billet already momentarily actuated the photoelectric relay 90 to momentarily close the contacts 91 which actuated the relay 110 to actuate the relay 136 to drop out the relay 113 to stop the conveyor motor '100 and the pusher motor 101 and lock the relay 110 in. The circuit to the conveyor and pusher starting relay 1 13 then is set up for actuating the relay 113 when the contacts 128 and 129 are closed. As the billet approaching the fifth pass 45 travels through the fifth pass, it actuates the photoelectric cell 60 to actuate the relays 151 and 153. The relay 153 actuates the relay 158 to reverse the conditions of the contacts 159 and 160 to change the selector guide, closes the contacts 155 to start the standard timer 165 and closes the contacts 156 to the variable timer 61, which then starts timing.

After a predetermined period of time has elapsed dependent on the setting of the contactor 174, the timer 61 times out to actuate the relay 188 which starts the standard timer 191. A predetermined period of time after the timer 191 has been started, it opens contacts 117 to prepare for resetting the relay 116, and also closes the contacts 192 to actuate the relays 120, 193 and 194. Actuation of the relay 193 closes the contacts 195 to release the latch 178 to reset the selector switch 171 before the timer 165 times out. Actuation of the relay 120 actuates the relay 124 through contacts 122, and actuation of the relay 124 closes the contacts 128 and 129 to actuate the relay 113 to start the conveyor motor 100 and the pusher 101 to feed a billet on the delivery end of the conveyor 15 to the conveyor 16, which feeds it into the roughing mill and brings another billet from the furnace to the delivery end of the conveyor.

As the timer 165 times out, it closes the contacts 221 to the stepping relay 175, and if the billet coming through the fifth pass 45 is longer than minimum, the timer 165 and the relay 153 are maintained actuated thereby, and the commutator 222 pulses the relay 175 a number of times proportional to the excess length of the billet to increase the time delay of the timer 61 proportionately to that excess length of the billet. Hence, the second succeeding billet behind the longer billet which is actuating the selector switch 171 will be delayed longer than if the billet actuating the switch 171 were of minimum length, and will not be dispatched immediately when the billet presently going through the roughing mill comes to the fifth pass and actuates the conveyor 15 to deliver that billet to the mill. Consequently, the alternate billets are maintained a safe distance apart as they go through the finishing mill, and also are dispatched as quickly from the conveyor 15 as may be safely done.

When the relay 113 is actuated, it drops out relays 110 and 136 to cause the relay 120 to be dropped out. The relay 120 starts the timer 125,-which shortly thereafter opens contacts 141 to drop out the relay 124. As the billet clears the cell 60, the relay 153 is dropped out, and the timers 165 and 61, which resets the timer 191, as it is dropped out. The timer 191 now reenergizes the relay 116. Each billet going through the fifth pass 45 sequentially actuates the timer 61 to start the timer 191 to place the call for the next succeeding billet in accordance with the previous setting of the contactor 174, the

relay 196 is actuated to reset the contactor 174 to zero; the timer times out, and, if the billet at the fifth. pass is greater than minimum, causes the commutator 222 to pulse the relay to move the contactor. 114m bring in resistors 172 in accordance with the amount the billet is excessive in length. This new settingof the timer 61 controls the dispatch of the secondly succeeding billet to the mill.

Thus, the above-described apparatus keeps the billets a minimum distance apart regardless of variation. in lengths thereof, and also keeps alternate billets as close together as possible since the pusher 10 and the conveyor 15 normally bring a billet to the delivery end of the conveyor 15 before the call for the billet is made at the fifth pass. That is, the billets are brought in less time to the discharge end of the conveyor 15 than it takes for the preceding billet to go through the roughing and the intermediate mills and call for the following billet. Since alternate billets are dispatched as closely together as possible, the capacity of the mill is maximum.

Certain features of the above-described apparatus are disclosed and claimed in copending application Serial No. 328,656, filed December 30, 1952, by I. F. Stoltz for Conveyor systems, now Patent No. 2,790,530.

It is to be understood that the above-described arrangements are simply illustrative of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

l. A system for initiating a second operation at a time interval after completion of a first operation, said time interval being responsive to the duration of the first operation, comprising means for sensing the duration of the first operation, means operated by the sensing means for forming pulses during said duration, a resistancecapacitance network including a variable resistance, means operated by the pulse forming means for varying the resistance in response to the number of pulses formed during said duration, -a vacuum tube connected to the resistance-capacitance network, and a voltage supply connected to the resistance-capacitance network for controlling conduction of the tube through said network, said conduction of the tube controlling the initiation of the second operation.

2. A system for delaying a second operation an interval responsive to the duration of a preceding first operation, comprising means for sensing the duration of the first operation, means actuated by the sensing means for forming pulses at a predetermined rate during the duration of the first operation, a stepping relay connected to the pulse forming means, a variable resistance, means connected between the resistance and the stepping relay for varying the resistance value of said resistance in response to each pulse received by said relay, a capacitance connected in parallel withthe variable resistance to form a resistance-capacitance network, a vacuum tube connected to the resistance-capacitance network, means connected to the vacuum tube for initiating the second operation in response to firing of the tube, and a voltage supply connected to the resistancecapacitance network for firing the tube.

3. A system for delaying the initiation of one operation in response to the duration of a prior operation, comprising means for sensing the duration of the prior operation, means operated by the sensing means for forming pulses during said duration, .a variable resistance, means operated by the pulse forming means for increasing said resistance in response to each pulse so that the value of the resistance at the end of said prior operation is directly proportional to said duration, a capacitance connected in parallel with the resistance to form a resistance-capacitance network having a variable time contion, and, a voltage supply connected to they resistancecapacitancenetwork for controlling thetube. through said.

netwoltk,

References Cited in the file of this peteut, UN T D TA ES A EN S,

910,478, Y'ates n, Jan. 19; 1909 8; George, May116, 1916: George ,No v. 6, 1928:: George. M Feta 9, 1932 Lee. July, 17, 1934; Gulliksen Aug. 29; 1939: Gay May 381, 1946-: Wilhelm Nov. 11, 19.47 Stirn. q Mar. 24, 19531 Williams Feb. 2, 1954 Stoltz Apr. 30, 1957

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