US2459041A - Automatic timing device - Google Patents

Description

Jan. 11, 1949. w. H. MITSCH AUTOMATIC TIMING DEVICE 3 Sheets-Sheet 1 Filed Feb. 9, 1946 QLZM M William H. Miksch,

Patented Jan. 11, 1949 UNITED STATES PATENT OFFICE AUTOMATIC TIMING DEVICE William H. Mitsch, Wheeling, W. Va,

Application February 9, 1946, Serial No. 646,674

This invention appertains to automatic timing devices generally, and more particularly to one which, while being capable of use as a sequence timer for any machine or process, is especially adapted to the operational control of resistance welding machines employing air pressure for applying the electrodes to the work.

At present, sequence timers are manufactured in a variety of forms, most of which depend for their operation upon the charge and discharge of capacitors in electronic tube circuits and wherein a condenser is charged through a resistor and, at a predetermined voltage, the electronic tube conducts enough current to operate a relay. Hence, by interconnecting a number of such circuits, a sequence of operations is controlled. Another form of sequence timer, to produce a variable time delay, employs filtered air which is forced through a graduated adjustable orifice, so that, by employing a number of such units, a sequence of operations can be controlled. Motor driven sequence timers are also well known but operate with the disadvantage that one time period cannot be changed without altering the I speed, or changing the other time periods.

However, in the instant invention, it is an object to make use of the magnetic flux of an expanding or collapsible field to obtain the desired time period and, to such end, four time-delay relays, operating on this principle, are employed to control a resistance welding machine of the spot or projection type, in the operation of which, four periods of time are required, the same being commonly known as squeeze, weld," hold, and oil.

Another object of the invention has to do with providing each of the aforesaid time-delay relays With a means of adjustment, so that, the time periods in the operation thereof can be readily and easily varied with precision to meet any of a Wide range of work requirements.

With the foregoing and other objects and advantages of equal importance in view, the invention resides in the certain new and useful combination, construction, and arrangement of parts and circuits, as will be hereinafter more fully described, set forth in the appended claims, and illustrated in the accompanying drawings, in which:

Figure 1 is a side elevational view, partly in section, of a panel mounting for certain of the operational elements of the timing device, and showing diagrammatically the circuit connections between certain of the operational elements 2 Claims. (Cl. 171-97) iii 2 and the operating parts of a welding machine, in accordance with the invention;

Figure 2 is a somewhat enlarged, fragmentary, section, taken on the line 2-2 of Figure 1, lookin in the direction of the arrows;

Figure 3 is a diagrammatical view of the control circuits of the device; and,

Figure 4 is a diagrammatical view, showing the order of operation of the several relays for controlling the welding machine through two complete cycles of its operation.

Referring to the drawings, and more particularly to Figures 1 and 2, the control panel, as it is exemplified therein, is comprised in a mounting panel l0, having an angled bracket l2, fastened horizontally on its rear side, to support four time-delay relays l5, i8, 20, and 22, in vertical position and in line thereon; two of the relays at each side of a rectifier tube l4, also supported on the bracket. The lower or heel end of the frame 24, of each of the relays, is fastened, by means of a screw 26 (Figure 2), to the horizontal portion of the bracket !2, while the heel end of the core 28 is fastened, by means of a screw 30, to the like end of the frame; the horizontal portion of the bracket being apertured, as at 32, to permit of access to the screw 30, without need to dismount the relay from the bracket.

In order to adjust the time period of opera tion of each of the relays l6, i8, 20, and 22, a collar 34, of copper or an alloy thereof, is slidably mounted on the core 28, between the heel ends of the frame 24 and he relay coil, and it is formed with an arm 36 extending in spaced parallel relation to the core and downwardly through an opening 46, formed in the bracket l2. One side of the arm 36 is formed with a series of rack teeth 38, arranged in mesh with a gear 42, which is keyed on the inner end of a shaft 44, that has bearing in the secured portion of the bracket l2 and the mounting panel ID; the opposite end of the shaft 44, at the front side of the panel, being provided with a control knob 46. Mounted on the shaft 44, between the panel Ill and the knob 48, is an index 48, having the form of a pointer which is turnable with the shaft and relatively to a graduated scale (not shown), delineated on the panel face. A guide roller 50 is mounted on a stud 52, fixed in the secured portion of the bracket 12, and has rotating contact with the arm 36, at a point thereon directly opposite to that of the gear 42, in order to accurately guide the arm in its linear movements of adjustment, when the shaft 44 is turned valve that, in turn, controls the operation of the movable electrode of the welding machine, and

the relay 53, the operation of the contactor during the weld period of the latter. A control switch til, preferably of the push button type, is.

carried at the free ends of a pair of leads extending from a set of circuit terminals 62 on the panel iii, while A.-C. power line leads are connected to a set of terminals 54, also on the panel, in circuit with a section S of the secondary winding,

S, of the transformer 56. The relay 56 is provided with a pair of fixed contacts and a movable bridging contact iita, with the fixed contacts connected to a pair of terminal posts 66, while the relay E3 is likewise provided with a pair of fixed contacts and a movable bridging contact 53a, with its fixed contacts connected to a pair of terminal posts 38. One of the terminal posts tit is connected to one side of the solenoidal valve coil 8t and the other terminal post to one side of the A.-C. power line and one of the terminal posts 58, of the relay 58, while the second, of the latter is connected to one side of the solenoidal contactor coil t6, which has its other side, along with the other side of the solenoidal valve coil 5%, connected to the remaining side of the power line.

The welding machine, as illustrated in Figure 1, is a conventional type, and includes a frame it, supporting a cylinder 12, housing a piston 74, which is connected to a movable electrode 62. The cylinder '52 is provided with an inlet 16 for connection to a suitable source of fluid pressure (not shown), such as compressed air, for the actuation of the piston M; a valve element 78 being mounted in the frame it? and adapted to be actuated by a solenoidal coil 80. A fixed electrode 84 is supported by, but insulated from, the lower part of the frame ill, for cooperation with the movable electrode 82. Leads 90, from the electrodes 82 and 84, are connected to thesecondary winding of the welding transformer T, the primary winding of which is connected to the power line, with one of its leads severed for connection with the fixed contacts of the welding circuit contactor, which contacts are adapted to be bridged by a movable contact member 38, upon the energization of the solenoidal coil 86 that occurs whenever the relay 58 is operated.

In the circuit arrangement shown in Figure 3, the contacts liia, ltd, and 20a, of the relays l6, l8, and 253, respectively, are normally closed, while all of the others thereof and of the remaining relays 22, 56, and 5%, are open. With the A.-C. power line leads connected to the terminal posts 64, the supply voltage is applied to the primary winding P, of the transformer 54, and the filament cathode of the vacuum tube 14 heats up; the energizing current for the filament cathode being furnished by the section S, of the secondary winding S of the transformer 54, and the direct current for the electromagnetic windings of the several relays It through 22, by the recti" fication of the A.-C. generated in the other sec tion. After the elapse of a few seconds, the tube M furnishes a direct current which immediately acts to energize the coils of the relays l8 and 22, causing the contacts 22a and 22b to close and the contacts 68a to open. By now closing the push button switch 58, the coil of the relay i6 is energized, causing the contacts ltb and lfic to close and the contacts ifia to open; the contacts 5617, when closed, forming a holding circuit for the coil of the relay l6, and the contacts itc, causing the energization of the coil of the power control relay and theclosing; of the contacts 55a; of the latter, on the solenoidal coil ilil for the operation of the compressed air valve 18 or the welding machine. With the closing of the contacts liib and ific, as aforesaid, the push button switch may be released to its normally open circuited position. With the opening of the contacts ita, of the relay it, the coil of the relay i8 is de-energized and, after a delay, the contacts lBa thereof closes; the delay, as before stated, being due to the time-delay, or slow release, characteristics of the several relays it, 58 2.3-, and 22. This delay interval constitutes the squeeze. period of the movable electrode 32 relatively to the fixed electrode 8t and the work interposed therebetween. With this closing of the contacts lSa, oi the relay is, the coil of the relay 28 is energized, causing the contacts 28b to close on the coil of the power control relay 58, which acts to close its contacts 58a on the solenoidal coil 86-, of the contactor of the welding machine. With the activating of the solenoidal coil 86, the contacts 88 close on the welding transformer, for

the application of the secondary current of the latter to the electrodes 82 and 84. At this time,

' the contacts Zila, of the relay 2%, open to effect a de-energizing of the coil of the relay 22, and, after an interval of time, its contacts 22a and 2212 open; the time delay interval here constituting the weld period of operation of the Welding machine. At the end of this delay period, the opening of the contacts 22b ole-energizes the coil of the relay 53, causing the contacts 58m to. open on the solenoidal coil 86 and the contacts 3% on the welding transformer and the electrodes 82 r and 84. At the same time, the contacts 22a, of

the relay 22, open and cause the de-energization of the coil of the relay 5%. After a succeeding elapse in time, constituting the hold period. of operation of the welding machine, the contacts it'a close and the contacts 5% and 460 open; the

contacts i ta closing the circuit on the coil of the relay it, while the contacts itb breaks the circuit around the push button switch 69 and. the con,- tacts 56c cause the de-energization of the coil: of

the relay along with the solenoidal coil 810,

with the result of the return of thecompressed air valve E8. to, its normal position and the consequent separation of the movable electrode 82 from the work. With the latter closing of the contacts iiitnoi the relay it, the coil of the relay i8 is energized, causing the contacts 811. to openon the coil of the relay 26, the de-energizing of which, after a delay in time constituting theofi period in the welding operation, causes its con.- tacts 29a to close, thus restoring the timing system to its original state, ready for a repeat op.- eration.

By reference to Figure 4, the sequential periods of inter-operation of the several relays l6, I8, 20', 22, 56, and 5B, is to be readily visualized through two cycles of welding machine operation, each cycle being performed in accordance with the above description. However, if the push button switch 66 is opened at the time indicated, all

further action of the timer will cease upon the completion of a single cycle of welding machine operation, but, if the switch 60 is held closed, the sequential operation of the relays will be repeated for any given number of cycles thereof. Again, if the switch 60 is opened at any time, after its initial closing to initiate the operation of the timing system, the operational sequence of the relays will continue to complete the welding cycle as before stated. Y

While in the foregoing I have described In invention in connection with an exemplary use thereof, it is to be understood that my timing system may be employed with any type of machine or process involving sequential operative steps other than as herein disclosed. Hence, while I have described my invention in its preferred embodiment, it is also to be understood that the words which I have used are words of description rather than of limitation, and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of my invention in its broader aspects.

What I claim is:

1. An electric sequence timer system, comprising a D. C. control circuit, an A. C. power circuit, a transformer including a primary winding connected in said power circuit and a secondary winding in said control circuit, a rectifier connected to and between said secondary winding and said control circuit to supply D. C. to the latter, a plurality of electromagnetic relays connected in said control circuit, a plurality of electromagnetic switches connected in said power circuit, and a manually operated switch connected in said control circuit, one of said relays having its winding connected in series with said switch and a pair of normally open contacts in series with said winding and shunted about said switch, a second of said relays having its winding connected in said control circuit and in parallel with the winding and contacts of said one relay and in series with a second pair of normally closed contacts of the latter, said second relay having a pair of normally closed contacts connected in said control circuit and in parallel with its winding, a third of said relays having its winding connected in said control circuit and in parallel with the winding of said second relay and in series with the contacts of the latter, said third relay having a pair of normally closed contacts connected in said control circuit and in parallel with its winding, a fourth of said relays having its winding connected in said control circuit and in parallel with the winding of said third relay and in series with the contacts of the latter, said fourth relay having a third pair of normally open contacts connected in said control circuit and in series with the winding of said one relay, said one relay having a third pair of normally open contacts connected in said power circuit and in parallel with the primary winding of said transformer, one of said electromagnetic switches having its winding connected in said power circuit in series with said third pair of contacts and having a pair of normally open contacts also connected in said power circuit and in parallel with its winding and in series with the winding of an electromagnetic device for the operative control thereof, said third relay having a second pair of normally open contacts connected in said power circuit and in parallel with the winding of said one electromagnetic switch and in series with a second pair of normally open contacts of said i'ourth relay and the winding of a second oi said electromagnetic switches, said second electromagnetic switch having a pair of normally open contacts connected in said power circuit and in parallel with its winding and in series with the winding of a third electromagnetic switch, said one electromagnetic switch having a pair of normally open contacts connected in said power circuit and in parallel with its winding, said third electromagnetic switch having a pair of normally open contacts connected in said power circuit and in parallel with its winding and in series with the primary winding of an output transformer, whereby, upon the momentary closing of said manually operated switch, the windings of said relays and said electromagnetic switches will be sequentially energized to perform their respective functions through a single cycle of operation.

2. The invention as defined in claim 1, with each of said electromagnetic relays of a delayed action type and provided with means for the adjustment of the time delay period of operation thereof.

WILLIAM H. MITSCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,742,367 Nettleton Jan. 7, 1930 1,922,089 Hovey Aug. 15, 1933 1,969,064 Field Aug. 7, 1934 2,092,021 Richterkessing Sep. 7, 1937 2,118,424 Watanabe May 24, 1938 2,123,063 Peters July 5, 1938 2,124,795 Roby July 26, 1938 2,140,576 Fisher Dec. 20, 1938 2,179,957 Roby Nov. 14, 1939 2,277,579 Burger Mar. 24, 1942 2,309,280 Stansbury Jan. 26, 1943 2,375,413 Guenther May 8, 1945 2,390,981 Binens Dec. 18, 1945

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