US2322663A - Electric switch - Google Patents

Description

'June 22, 1943. F. H. ROBY ELECTRIC SWITCH original Filed July 1, 1937 4 Sheets-Sheet l NVENTOR June 22, 1943.l F H, ROBY 2,322,663

` ELECTRIC SWITCH Original Filed -July l, 1937 4 Sheets sheet 2 z5 i [5, ,79 l if L jv O 9 l O /7 4 vn/ E /N VEA/TOR June 22, 1943. F. H. ROBY 2,322,663

ELECTRIC SWITCH Original Filed July 1, 1937 4 Sheets-Sheet 3 i! /NVENTo/e June 22, 1943.

F. H. ROBY ELECTRIC SWITCH original 'Filed July 1, 1937 4 Sheets-Sheet 4 y f. M il ,E+ m W a /f 7, N w 3T; gl? /f/ f L a L 7 if wg 2 l@ L 4, /v2 i 7 s, L j# 3 7 W7 m27 wlvvk w Patented June 22, 1943 ELECTRIC SWITCH Frank H. Roby, Milwaukee, Wis.. assigner to Square D Company, Detroit, Mich., a corporation of Michigan @riginal application July 1, 1937, Serial No.

151,358.v Divided and this application November 18` 1938, Serial No. 241,093

3 Claims.

This invention relates to an electric `timing switch used for controlling and timing a plurality of operations such as the various apparatus in a complete electric welding cycle, and has ior its primary object `the provision of a motor driven repeat timer which shall be extremely simple, economical and durable and which shall afford a wide range of speeds easily controllable as desired.

This application is a division of application, Serial Number 151,358, filed July 1, 1937, for Welder control system and electric switch employed therein, now Patent No, 2,179,957 granted Nov. 14, 1939, for Welder control system.

Another object of the invention is an improved motor driven timing switch which shall obviate the necessity of a magnetic clutch or other means for picking up the timing contacts on the switch.

Another object of the invention is to provide an improved motor driven timing relay having a plurality of normally open and closed contacts and an electric motor driven reciprocable operting member for actuating the contacts.

Another object of the invention is the provision of a timing relay including a plurality of cooperating contacts adapted to be successively operated by a reciprocable member with improved means for adjusting the stationary contacts to provide independent control of the Varying periods of engagement and disengagement of the contacts.

Other objects and features of this invention will be readily apparent to those skilled in the art from the following specification and the appended drawings illustrating certain embodiments of the invention in which:

Figure 1 is a front elevational View of a control panel according to the present invention.

Figure 2 is a side elevational view of the panel shown in Figure 1.

Figure 3 is'a vertical sectional view on the line i III- III `of Figure 1.

Figure 4 is a partial horizontal sectional view on the line IV-IV of Figure 1.

Figure 5 is a schematic wiring diagram for the control panel.

Figure 6 is a simplied wiring diagram of the Welder control system showing all its component parts,

Figure 7 is a partial simplified wiring diagram of a modified system.

Figure 8 is a detail section of the panel .connection terminals.

Figure 9 is a generally diagrammatic view lshowing the operating parts of a welding machine towhich the control system may be applied.

Tlie electric timing switch according to the present invention is illustrated and described in connection with control apparatus for electric welding, whichl apparatus is shown as comprising an exterior supporting or mounting plate I having mounted thereon a terminal board 2 and a panel 3 supporting the control elements of the system and removably mounted with respect to the mounting plate I and the terminal board 2. Upon the panel are mounted a transformer 4, a control relay indicated generally at 5 and a timing relay indicated generally at 6. vThe control relay 5 may be of conventional form and its details of construction form no part of this invention. It is a magnetically operated relay of the normally open type having an'operating coil 'I shown only schematically in Figures 5 and 6 and is provided with three cooperating sets of contacts 8, 9, and Il.

The timing relay 6, according to the present invention, is inclusive, and embodies a reciprocable insulating rod I2 having mounted thereon spring biased bridging contact elements I3, I4, I5, and I6. Each of these bridging contacts is biased on the rod by means of a compression spring I1 disposed about the rod and having its end remote from the bridging contact received within a washer I8 pressed against a stop I9 on the rod. This construction is duplicated for each of the bridging contacts with the exception of the lowermost contact I6 which is reversed in direction and is closed at the extreme lower position of the rod I2. The rod I2 at its upper end is attached by means of studs 2| within a slot in a member 22 to which is pivotally connected a pair of arms 23 as by means of a pivot pin 24, the arms 23 being rigidly connected by a cross piece 25 and pivoted at their opposite ends to a base piece 26 as by means of a pin 2l. The base piece 26 is rigidly supported on the panel 3. A stop 28 is rigidly secured to the panel 3 and a compression spring 29 disposed between the member 22 and the stop 28 serves to bias the rod I 2 in a downward direction. At its bottom end the rod I2 is similarly connected to a member 3l pivotally mounted on arms 32 which are, in turn, pivotally connected to a base piece 33 rigid with the panel. The bottom end of the member 3l is provided with a ball bearing roller 34 which bears against the operating Surface of a cam 35 which is rigidly mounted on a shaft 36 and by its rotation serves to effect reciprocation of the rod I2. The shaft 36 is driven by an electric motor 31 through a set of reduction gears within the casing 38 which may be of conventional form. The spring elements 39 (Figure 2) pass through the pivot pins for the arms 23 and 32 and serve to insure the proper rotation of the pins Within the bearings provided within the members 22 and 3l.

The operating motor 31 is herein illustrated as a series Wound motor provided with a poten-- tiometer circuit to give variable speed operation. This system of control not only provides for variation in speed over a relatively wide range but also gives very favorable accelerating characteristie when the motor is started only with the initiation of the welding cycle. This potentiometer arrangement includes the rheostat by-passing and in series with the motor armature, as more clearly illustrated in the simplified schematic wiring diagram of Figure 6 which shows the resistance in series With the series wound motor eld and with a variable portion of this resistance by-passed by the motor armature. vThis arrangement, in addition to the above stated advantages, also results in a reduction in the precentage of speed change due to fluctuations in line voltage and gives to the series motor operating characteristics more nearly approaching those of a variable speed, direct current motor of the shunt or compound type.

The timing relay includes a distinct arrangementl for varying the positions of certain of the stationary contacts. Each set of stationary contacts is mounted upon an insulating block and these are here represented in order from the top to the bottom by the numerals 43, 44, 45, and 46.

Each of the stationary contacts includes a terminal connector 41 extending to the left hand side of the blocks 43 to 46 and having mounted thereagainst posts 48 extending forwardly of the case Yof the lowest sets. Nuts 52 may be pro- A vided for preventing undesired adjustment or movement of the stationary contacts. 'I'his arrangement is shown in Figures l and 2 and in enlarged form in Figure 4 and provides means notl only for mounting the stationary contacts but for providing adjustment for each stationary contact individually. The end blocks 43 and 44 supporting the sets of stationary contacts are rigidly secured rto the panel 3 by means of studs 53 and located in these extreme blocks and extending therebetween are guide rods 54 upon which are slidably mounted the intermediate contact supporting insulating blocks 44 and 45. Compression springs 55 are provided between the end and intermediate blocks and serve to bias lthe blocks 44 and 45 to intermediate positions remote from the blocks 43 and 46. Adjustment rods 56 and 51 are provided, the rod 56 being secured to the block 44 by stud 58 and extending slidably through the block 43 and pro- Y vided at its upper end with an adjusting nut 59. The rod 51 is tied to lthe block 45 by means of a stud 6I and extends` slidably through the block 46 and is provided at its lower end with an adjusting nut 62. is seen that while the stationary contacts cooperating with plates I3 and I5 can only be adjusted by means of their individual mountings -on the blocks 48, means is provided for quick With this arrangement it stationary contacts cooperating With the bridging contacts I4 and I5 by tightening or loosening the studs 59 and 62 to shorten or extend the rods 56 and 51 and :to effect movement bodily of the contact supporting blocks 44 and 45 and hence provide for quick and easy individual and separate adjustment of the contacts cooperating with the bridging contact plates I4 and l5.

The panel 3 is supported on the back plate I in spaced relation by means of spacer bolts 8| at the corner of the panels over which the panel 3 is mounted and maintained in rigid supporting relation by the nuts 82 at the front. The terminal board 2 is comprised of a pair of insulating blocks 83 and 84 rigidly secured to the front face of the back plate I and having mounted thereon a plurality of terminal connectors 85 having connected thereto rigid contact elements 86. Cooperating with the contact elements 86 are contact surfaces 81 mounted on connectors 88 on the back face of the panel 3. The connectors 88 are loosely received in recesses 89 in an insulating block 9I which is rigidly secured to the back face of the panel 3. The connectors 86 are maintained in place by 'the engagement of their terminal screws 92 in recesses in the back face of the panel. Compression springs 93 are provided biasing the contact surfaces 81 away from the pane-1 3 and providing contact pressure between the contact elements 86 and the contact surfaces 81 when the panel 3 is in supported relation with the back plate I. The internal wiring of the control elements mounted on the panel is connected terminally to the terminal screws 92 on the connectors 88 and the exterior control wires leading to the various operating and operated elements exterior to the panel are connected to the terminal connectors B4. By this means it is seen that upon removal of the nuts 82 the panel 3 and the control elements supported thereon may be directly removed from, the back plate for the replacement of an entire panel and for repair without disturbing the exterior connections.

The welding control system herein illustrated is intended for operation with a pneumatically operated welding tool having an operating valve in the handle and a check valve in the airline leading to the handle to prevent leakage of air through the operating valve in the welding tool or the packing gland in the head of that tool. Two single pole Welder contactors, each having a separate operating coil and connected one in each side of the welding transformer primary are used, although it is obvious that a double pole contacter having a single operating coil may be used with equal facility without changing the wiring connections as the operating coils of the single pole contacts are connected in parallel. The welding cycle is divided into four periods corresponding to a delay period to permit the pressure to be built up Within the welding tool upon the welding electrodes, a weld period during which current is passed through the work between the electrodes, a hold period in which the current is turned off but the pressure maintained upon the electrodes and an oil period in which the pressure on the electrodes is released. It is, of course, to be understood 'that while the system has been shown in its most detailed form for the pneumatically operated welder, it can obviously be applied with simplifications to mechanical and hand operated electric welding machines with the same welding cycle or a simplified cycle omitting either or both of the l"hold and vdelay periods, depending upon the particular type of machine used and the requirements of the welding.

The internal wiring diagram of the panel is shown in Figure but will be explained hereinafter with reference to the schematic simplified control diagram of Figure 6. The panel wiring of Figure 5 terminates in I0 terminals designated as pairs of terminals 63, 64, 65, 66, and 61. The terminals 63 are line terminals to which the power line is. connected. The terminals 64 are connected to the welding contactor operating coils. The terminals 65 are connected to the check valve operating co-il. The terminals 66 are connected to the operating coil for the operating valve of the pneumatically operating welding tool. The terminals 61 are connected to an voperating push button. In the simplied diagram of Figure 6 the motor 31 is split up to include the series wound eld 68 connected in series with the rheostat 4| and an armature 69 adjustably connected across the register 4I. 1I designates the operating push button. 1 designates the operating coil of the control relay 5. 12 designates the operating coil for the valve in the pneumatically operated welding tool which supplies pressure to the welding electrodes. 13 and 14 represent the operating coils of contactors 15 and 16 in each side of the welding transformer primary. The welding transformer is designated at 11 and the welding electrodes are schematically shown at 18. The operating coil for the airline check valve is shown at 19.

'The operation of the Welder control system will now be described. 'The rheostat 4| is adjusted to give the desired speed of operation and the contact blocks 44 and 45 are adjusted in position to give the desired weld and olf periods respectively. By adjusting the cont-act supporting block 44 upwardly a shorter weld time is obtained and by adjusting the contact supporting block 45 downwardly a shorter off period is obtained. The differential or spacing difference between the blocks 44 and 45 will determine the delay and hold periods which will, of course, be uniform if a uniform cam is used. For differential in these two periods variable shaped cams may be used to secure a predominance of delay time or a predominance of hold time as desired, these cams being substituted for the cam 35. To initiate a series of welds the push button 1I is closed, thus placing the motor 31 across the line and initiating its operation. The rod I2 will then begin to move as the motor accelerates its Speed. As long as the bridging contact I6 remains open the weldingcycle is not initiated but when the contact I6 bridges its corresponding stationary contacts upon the extreme lower movement of the rod I2, energization of the control relay operating coil 1. is momentarily effected and the control relay 5 closes, maintaining itself through bridging contact I3 and the control relay contacts 9. The bridging contact I6 is so regulated with relation to its cooperating stationary contacts as to be closed only during the eXtreme lower movement of the rod Iq and the bridging contact I3 is regulated with respect to its cooperating stationary contacts as to be open only during the extreme lower movement of the contact bar I2. The duration of the opening of contact I3 is desired to be coincident with or not appreciably greater than the closing of bridging contact I6 so that once the control relay 6 has been operated the bridging contact I3 will -be closed so as to have the maintaining circuit regardless of opening of the push button 1I. The bridging contact I6 is by-passed by control relay contact II but the circuit for the operating coil 1 of the control relay 5 will not be maintained if the push button 1I is open unless bridging contact I3 is closed. Assuming now that contact I6 is closed, energizing the cooperating coil 1, the control relay 5I closes its contacts 8, 9, and II. Bridging contact I3 is also closed at this time so even if push button 1I is let up one complete welding cycle will Abe performed. Closing of the control relay contact 8 energizes the operating coil 19 for the check valve and opens airline pressure to the welding tool operating valve. As the rod I2 moves upwardly'the bridging contact I5 engages its cooperating stationary contacts and energizes the welding tool check valve operating coil 12 through the control relay contact 9. As the rod I2 continues to move upwardly bridging contact I4 closes itsv cooperating stationary contacts and energizes the operating coils 13 and 14 for the welding contactors 15 and 16 which close passing current through the work between the welding electrodes 18. The rod I2 continues to move upwardly until it passes the highest point on the cam 35 and then in its downward direction first separates the contact I4 which deenergizes the welder contact operating coils and interrupts the current through the work and in its continued downward movement separates the bridging contact I5 which deenergizes the check valve on the welding tool `and relieves the pressure on the weldingelectrodes. If the push button 1| has not been held down the rod moves downwardly until bridging contact I3 is open which opens the holding circuit through the operating coil y1 of the control relay 5 and drops out the control relay, thus deenergizing the entire system. It is to be noted that when push button 'II is released immediately after closing of the control relay, the control relay is maintained through its contact 9 and bridging contact I3 and that the motor circuit is completed through control relay contacts 9 and I I and bridging contact I3. If the control push button 1| is maintained in depressed position the system will continue to make successive welds in the manner described until the push button is released and bridging contact I3 opened.

It is to be particularly noted in the Welder control system disclosed that energization of the system to initiate a welding cycle is determined by closing of the control relay 5 and this can be effected only when the bridging contact I6 is closed, which occurs only in the off period of the cycle and which is preferably of a relatively short period in the eXtreme lower position of the operating rod I2. With this system it is impossible to energize the welding cycle at any point except in the off period which is a necessary feature of operation as it would obviously be undesirable to energize the system, for instance, when the Welder contactor control contact I4 were closed without allowing for a delay period to effect building up of pressure on the Welding electrodes. If the push button 1.I should be closed while the operating rod is in a position where bridging contact I6 is open either in the upward or downward direction, the rod I2 will continue in its motion without energizing the system until the bridging contact I6 is closed, whereupon the control relay is energized and the welding cycle initiated. Using an operating motor for the timer having high acceleration, it is possible that even in the Worst possible case where the rod I2 is in a position where the bridging contact I6 is closed with the motor stopped so that the control relay is immediately energized, it has been found that the motor builds up in speed fairly well during the delay period so that the weld period is not undesirably long for most classes of operation, even in the first weld.

Where extreme accuracy in the rst weld is desired the motor 31 may be connected to the line and brought up to speed before the push button is operated to initiate the weld. This would necessitate simply placing the push button 1I, in Figure 6, in the circuit leading from the right hand side of the transformer 4 to the contact set including bridging contact I6 rather than in the circuit including the motor, which arrangement has been shown in the partial diagram of Figure 7, where an additional switch 19 is provided for connecting and disconnecting the motor as desired. With this operating arrangement the switch 'I9 is closed to initiate motor operation and thereafter closing of the push button 'H will effect initiation of the welding cycle without the necessity of bringing the motor up to speed. Again, however, regardless of the position of the rod I2 when push button 1| is depressed, the control relay will not be energized to energize the welding control system until the rod I2 has reached a position at which bridging contact I6 is closed so that, in each case, the control system is energized at the off period of the cycle.

The arrangement shown partially in Figure 'l is adapted for use not only with the type of motor particularlypdescribed but also with a syn- 5.

chronous motor utilizing any conventional type of variable speed of the welding tool. This arrangement secures not only extremely accurate timing but also permits the expansion of the system to include the synchronization of the operation of the welding contactors to the preferred point on the voltage wave of the supply source.

Figure 9 illustrates a conventional type of welding machine in diagrammatic form to which the control system of the present invention may be applied. This includes a frame IUI which supports a cylinder i02 in which is disposed a piston |03 connected to a movable electrode |04. A cooperating electrode IE5 is mounted on the lower part of the frame and insulated therefrom 1 by an insulating sleeve IUS. Leads |01 are connected to the secondary of the welding transformer to energize the electrodes |04 and |05. A fluid pressure inlet |08 is indicated ior connection to any suitable source of iluid pressure, preferably compressed air, which is used to actuate the piston |03 within the cylinder |92. The valve is shown in the frame IDI and includes a movable valve portion |09 adapted to be moved by the solenoid coil '|2. The position of the parts illustrated in Figure 9 is at the conclusion of a hold time in which the coil 'l2 has just been de energized to move the valve portion |69 downwardly and connect the inlet port on the under side of the piston |03 with the source of iluid pressure. The force is now exerted tending to move the upper electrode to separated position into the dotted line position of the piston as shown. To move the electrode to apply pressure to the work the coil 'I2 is energized moving the valve portion |09 upwardly and connecting the port on the upward side of the piston with the source ol fluid pressure, thus moving the electrode downwardly into engagement with the work. The structure illustrated in Figure 9 is entirely conventional and is shown herein simply to illustrate one type of welding machine to which the method and control system of applicants invention is applicable.

While certain preferred embodiments oi the invention have been specically disclosed, it is understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the iollowing claims.

What is claimed is:

l. An electric switch for the operation of a plurality of electric circuits in timed sequence comprising a reciprocable member, means for electing reciprocation of said member, a plurality oi cooperating sets ol contacts, means effecting operation oi' said contacts upon movement ol` said member, at least certain of at least the stationary contacts in said sets being mounted for relative movement and including relatively stationary insulating blocks upon which the opposite extreme contacts are mounted and intermediate movable insulating blocks upon which other contacts are mounted, spring means bias ing the intermediate blocks for movement relative to the extreme stationary blocks, and adjustable means interconnecting intermediate and extreme blocks for regulating the distances between them to vary the time of operation of the contacts.

2l. In an electric switch, spaced insulating blocks mounted in relatively xed position and carrying contacts thereon, guide rods interconnecting said blocks, a pair of movable insulating blocks slidably disposed on said rods between said ilrst mentioned blocks and also carrying contacts thereon, spring means biasing each of said movable blocks for movement in one direction, adjustable means interconnecting each stationary block and the adjacent movable block and cooperating with the spring means to adjustably locate the movable blocks, and movable means for eil'ecting operation of said contacts in a cycle determined by the position of the movable blocks.

3. In an electric switch, spaced insulating blocks mounted in relatively fixed position and carrying contacts thereon, guide rods intercon- 'Y necting said blocks, a pair oi movable insulating blocks slidably disposed on said rods between said iirst mentioned blocks, contacts on said movable blocks; spring means disposed between each stationary block and the movable block adjacent thereto, an adjusting rod extending through each stationary block and the adjacent movable block, said rods being tied to one of the blocks at one end and having an adjusting nut at the opposite end bearing against the other block whereby the spacing between the blocks may be adjusted, a reciprocable member, and means for reciprocating said member to effect cyclic operation of the contacts.

FRANK H. ROBY.

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