US2632122A - Control mechanism - Google Patents

Description

March 17, 1953 w. DE l.. BERRY Erm. 2,632,122

" CONTROL MECHANISM Filed sept. s, 1946 2 SHEETS- SHEET 1 March 17, 1953 w. DE l.. BERRY Erm.

CONTROL MECHANISM Filed Sept. 3, 1946 2 SHEETS- SHEET 2 Patented Mar. 17, 1953 UNITED STATES PATENT OFFICE V2,632,122 lcoNrRoLl MEcHANIsM tion .of ADelaware 4'Application September 3, 1946, SerialNo. 694,644

(Cl. S10-93) 5 Claims. 1

This inventionfrelates toza 4control system and mores-specifically to a system for controlling the operation of a motor driven press welder. In the voperation ofthat Vclass of heavy machinery suchas punch pressesv and press'welders which perform a pressing, stamping or clamping operation a heavy ram is provided which is moved with respect tora stationary platten. vConventional drivingmeans for the ram in these machines has heretoforebeen in the form of a large heavy iiywheel that is driven by the motor and suddenly clutched to the driving means for the ram bymeans of a jawk clutch. This causes high initial stresses in the parts'and attendant noise and vibration. Italso Vmakesthe service problem a major one. In l,order to eliminate the problems attendant such construction and provide a smooth rapid acceleration of the ram it is proposed to utilizean electromagnetic clutch between the ywheel and the ram drive so that there will 'be no direct mechanical connection betweenv parts which will be driven by a magnetic flux interlinkage.

It is therefore anobject of our invention to provide a control system for an electromagnetic drive for heavy machines. l

V,It is a further object of our invention to provide a control system for .an .electromagnetic clutch and brake for heavy machines.

It is a still further object of our invention to provide .a control system for an..electromag neticdrivefor press Welding machines.

With these and other yobjects in view which will .become apparent .as .the specication proceeds, .our invention .will be best understood 1 as indicated by-arrows with similar four lines at-the top of Figure lA.

Figure 2 is a diagrammatic showing of the phased mechanical operation of the cam operated switches.

Figure' isa schematic diagram of the drive between the motor and rvmovable machine part.

Inasmuch'as each relay coil when energized actuates a plurality ofswitch contacts either to open or close the same, it would be confusing to show-'on the drawings the connections'between each rrelayactuating coiland its associated -contacts and soforpurposes of this applicationthe relay coils will be designated by letters, such for :example as A and the contacts actuated thereby by the same letters plus identifying numerals such as AI and A2 etc., depending upon the number of contacts actuated thereby.

Referring now more specifically to the circuit, there is shown a three phase power supply,rlines 2, 4.and 6 connected to a main control switch 8, three input conductors,'lines I0, t2 and Yi4 being connected to the opposite side of the switch. Line I0 terminates in a pair of parallel conductors ISand vI8 which :are in turn connected to kone terminal .20 of the three phase driving motor 22. In eachof the lines iE and i8 there is a switch vFI and'RI respectively. Lines I2-and I4 are cross-'connected vby lines 24 and 26, which connections'have.serially incorporated therein switches F2 and F3 respectively. serially interposedin lines I2 and I4 are switches R2 andR3, line i2 being connected to terminal 23 and line iI4 to terminal 3Ilof motor 22. Connected across lines i2 and I4 bylines 36 and -38 is primary 32 of transformer 34. This. is a power transformer which provides the necessary energy for the various actuating relays. Lines 36 and 38 are connectedahead of the various switches F2, F3,1R2, R3 so that the transformer will Vbe energized assoon as the main switch 8 is closed. Power line 40 is connected to line l2 between these switches andthe motor 22 and the associated power line 42 is connected to line I4 in like manner. These latter lines therefore 4are not energizedunless either the series F `switches or the series R switches .are energized. -It will thus be obvious that as soon ,as the main power switch is closed the motor will be energized to run in one direction by the closure of the F series switches, or forward, or it may beenergized to rotate in the opposite direction or reverse by the closure of the R series switches.

Secondary 44 of transformer 34 has line 45 connectedto one terminal and 48 connected to the opposite to provide lower voltage power leads than lines 40-42, to provide current for the various relays and further switches. Directly connected across between these lines is an indicator lamp- 50 which indicates to the operator whether or not the power supply is energized. Directly connected in series relation between. lines 46 vand 48 are a series of control switches and energizing coils for controlling the forward andreverse contacts F and R` which include a 'switch 52, a'stop `switch 5.4, a manually closed `switch 56 which the operator closes to energize the motor 22 in a forward direction, a normally closed contact R4, relay coil F and a normally closed contact 58 which is thermally controlled by motor temperature and is operated by coils 60 in the motor line. Thus if the temperature of the motor exceeds a certain Value this safety switch 58 will open. It will thus be obvious that switches 52, 54, R4 and 58 under normal conditions Would be closed and therefore when the operator depresses switch 56, relay coil F will be energized to close the F series contacts and energize the motor 22 to rotate in a forward direction. In shunt around the switch 55 is a normally open contact F4 which is closed upon the energizatien of the F coil to maintain coil F energized but permit release of switch 55.

In parallel te that portion of the circuit just Idescribed including switch 5o, contact R4 and relay coil F is a second circuit for controlling f the reverse rotation coil R which has in series with it a contact F5 which is closed when relay vcoil F is de-energized, a reverse switch 6I operated by the operator and a similar hold in shunt switch R5 which ley-passes manual switch 6l. Through this circuit relay R can 'bev energized by the manual closure of switch El which in turn actuates all the R contacts and causes the motor to run in a reverse direction. At this point it will be obvious that there is provided f conventional switching means for a three-phase motor to cause the same to rotate in either one of two desired directions.

This motor is mechanically connected to a iiywheel which must be placed in spaced driving relation with some means en the shaft of the press so that the same will operate. This is accomplished through magnetic iiux clutching means between a drum on the press shaft and this flywheel.

The control for the magnetic clutching means will new be described. Switch 62 is directly cennected to line 4o for power and is operated or maintained in normally closed position by air lpressure in a line (not shown) which provides air to booster cylinders to give the press an initial push to start the same. Thus, under normal conditions this switch would be closed as long as air pressure is provided to the cylinders. A second switch B4 is connected in series with the switch 62 and also is normally closed by :air pressure, 4but in this instance it is by the air pressure provided to the solenoid operated air brake so that the device will not operate unless air is being provided to the brake system. Further in the series connection with the two switches t2 and E4 is a fuse 65. A series of emergency stop buttons 63, lo, l2 and 'i4 next fellow in series relation but placed, of course, in various convenient places around the machine and are normally closed but can be opened te deenergize the whole system if the necessity arises.

Connected to the last of the emergency switch buttons is a relay contact HI which is opened upon deenergizatien and is controlled by the relay Icoil H which is itself connected across power lines 46 and 48 and ha-s in series there-y with only the inch-run switch I5. It will be obvious that when this switch is moved to the position shown er run position the relay coil I-I will -be energized, but whe-n it is moved to its upper contact it relay coil I-I will be deenergized and the machine will be capable of inching operation only which will be described. In

r. continued series relation there is connected contact R5 which is closed when the relay coil R is deenergized and opened upon energization of relay coil R, therefore when the motor 22 is running in reverse direction this circuit may not be energized. Line 86 is connected at a point between switch I4 and contact HI and extends to contacter Cl which is in turn serially connected with lcontacter Si and relay coil E, the opposite terminal of which is connected to power line 48. Coil E is the relay control coil for the solenoid operated mechanical brake.

Line 82 is connected at a point between centactors Hl and R8 and extends to normally closed contacter LSS which is operated by one of a series of synchronously driven mechanical cams which appear in Fig. 2 and Whose relationship is adjustable and will be later described in more detail. Contacter LS@ is in turn serially connected with contacter L53 and contacter E3 which is opened upon deenergization of coil E and closed upon energization thereof. Connected to line Bil is a normally closed contacter H2 which is opened whenever relay H is energized, which under all normal conditions is when the switch 'l5 is in run position. In se-ries with contacter H2 is a manually operated switch 34 which is the inch operation switch. In other words, when switch lo is moved to contact point 18, the operator may then inch the machine along by closing switch 8a and opening it when the machine has proceeded to the desired point. Continuing in serial relation to switches H2 and 84 is switch LI which is controlled by the re- E lay coil L which in turn is directly connected across the power lines 45 and 48 and has in series therewith only a time delay operated switch This is cent-rolled by an 4electronic thermal relay 88 in circuit with the power tubes 96 and 92 which provide current for the magnetic brake and clutch and this prevents the operation of the whole circuit until the tubes have had an opportunity to heat up.

Continuing in the series relation with the main control line are a series of what is known as run buttons or manually operated switches 94, the number depending upon the number of operators which the machine is te have, two buttons being provided per operator. These switches are normally biased to upper position as shown and when in that position close the circuit through relay coil A to -power line 48. When, however, they are in depressed position they tend to complete a circuit through relay coil B. In series relation, however, to the circuit for relay coil B there is a second contacter L2 operated by coil L which maintains the switch L2 closed during the running period of the machine. Also in series relation to coil B is a contacter Al which is controlled by relay coil A and is closed when this coil is energized. To the left of the serie-s of switches operated by the run buttons in this circuit is a switch contacter Ml which is closed upon deenergization but opens upon energization of the relay coil M which is the weld cycle initiating relay the intent being to maintain this circuit open when the welding control is dominating and `actually 4performing welds so that the press motor may not be moved at this time.

A conductive line sa is connected between switches Re and 94 and extends te a cam operated switch L52, the opposite side of which is connected to line 38, which in turn extends to an intermediate point .between switches BI ,and B2. In shuntrelation around the cambperatedswitch LS2 isa secondcam operated switch LS'|. -Also connected to line 96 is aV contactor NI which is controlled lby relay lcoil N and closes upon energization thereof. Inseries with this switch is a pressure actuated switch which is'maintained closed by pressure in the welding gun return line and opens upon the release thereof. rShe :opposite side of the pressure switch is connected through line YH32 with a point intermediate switches Ai and L2. 'The two lines just to the left lof coils C -andD which are shown by arrows are connected into the selector switch on the weld timer. The inch and run'switch l5 is shunted by contactor M2.

CoilsA J andV K which are connected iniparallel are the coils primarily intended to actuate the dynamic brake of the drive and have serially in' sequence the following switch contactors: H3, L54, PI, the latter contact being opened when the press is not in motion and closed when it is in motion, and L3. Shunting contactor LSE is a second cam actuated contact LSS and shunting both contactors H3 and L54 is a contactor DI. A holding circuit for relay coil A is provided around the run buttons 94 through conductive line |94 which has in series relation three contactors LSL LS and A2. The mechanical solenoid brake is set under normal spring bias and the relay E is energized to remove the braking pressure by closure of two contacts El and E2 which are in series with the brake coil T. The three elements being in series across the lines 46 and 48.

The relay coil M is the welding cycle initiating relay and when this coil is energized the welding machine proceeds through its normal cycle of welding, the press during this time remaining in stationary clamped position. Serially connected with the relay coil M are the following switch contactors LSE, H5, Eil, P2, vopen when press is not in motion and closed when press-is in motion and N2. Connected at an intermediate point between switches H5 and E4 in this series connection is a line |95 which extends to a control circuit from the welder indicated by the two downwardly directed arrow tipped lines shunte'd by a switch m3 and thence to the lrelay coil N. This switch iii 'is a limiting switch which is operated by the last contact ofthe Welder timer. In shunt around this welder controlled switch is a holding contactor N3. In series with the relay coil P between lines 46 and 48 is a controlling switch Hl which is operated by the speed of the member driving the platen and is closed Vat low speeds and opened at higher ones, such for example as those vabove R. RM.

The power transformer ||2 which supplies'the power for the magnetic clutch and brake' has its primary H4 connected across lines 40 and 42 `of the power supply and has in series therewith two control contactors D2 and C2 and in shunt relation around each of these contactors are further switch contactors Ki and JI respectively. The secondary HG of this 'transformer is center tapped and connected to line HB. One of the outside terminals is connected through line 23 with a rectifier tube Sil the oppositesecondary terminal is connected through line |22 to a second rectifier tube 92. Supplying the filament power for these rectifier tubes is a transformer |24 whose primary |25 is connected between lines 4c and 42 and whose secondary |2B'has its two outside terminals connected to lines |30 and |32 wlfiichzextend` to the filament circuits of tubes 90, 92.:and 88. Secondary |28'isalso center tapped andline |34 connected thereto.

The operating coil'l36 for theelectromagnetic clutch is connected directly between lines |341and |13 and has in series relation thereto coil S which'is provided with some time delay means, switch contactor D3 and C3, on one side and a pair of torque limiting resistors |38 and switch contactors C4 and D4 on the opposite side. The two torque limiting resistors |38 are by-passed by va shunt circuit which includes switch contactors H5 `and H4. The dynamic brake coil `on the other hand shown at It!) is also connected between lines i3d and H8 and has in series relation therewith on one side contactor J2 and' K2 and on the opposite sideKS and J3.

Figure 2 diagrammatically showsthe phased mechanical operation of the various cam operated switches, the shaded portions indicating the time periods ina complete cycle of rotation during which the switch'actuated thereby is closed and the unshaded or clear portions that period of time during which that switch is open, a'full cycle of the ram being thus represented by a fiat `rectangle and showing that time during which the machine starts from its initial lowered position, is raised to clamp the welding electrodes which are then fired and the platen lastly returned to its lowermost position. The diagrams as will be noted are numbered from i to 9 and the switches in the circuit diagrams of Figs. 1 and 1A have been identified as LSL 2 or 3 as operated by cams i, 2 or 3 of-Fig. 2.

In Figure 3, the motor 22 is shown provided with a pulley 23 driving a rotatable flywheel 25 through a belt 21. The iiux generating coil |36 is carried by the ilywheel. Rotatably mounted within the ywheel is a spider 29 made of magnetizable material which is an integral part of a shaft section 29. vA crank 3| is rigidly connected to the outer end of the shaft section and a link 33 is pivotally connected to the crank end and to a movablepart 35 of a machine or press which it is desired to drive or move. A friction brake 3l' is spring biased toengage the shaft to .prevent its rotation by spring 39 and may be moved away from brakingposition by solenoid' E. The flux brake coil |40 is supported on a stationary drum`4| within the spider. Thus, with the iiywheel continuously rotating when coil |36 is energized, the spider will be driven thereby through the flux linkage and when the coil |3 is deenergized and coil IM! energized the spider willv have a braking action vapplied due to the stationary flux eld. The friction brake is operated to vremove the brakingk action by energization of coil E in proper timed relation as will be further described.

The operation of the device will now'be 'explained in detail. Assuming that the machine is de-energized and in a position of rest, which under normal circumstances would be when the platten is lowered position ready for the insertion of a part to be welded between the upper and Ylower electrodes, the switches all being shown, `either open or closed in the position when its'operating coil is cle-energized. Switch is then vvclosed which vappliespower to transformer Se. `The power circuit to the driving motor 22 may be completed by closing of either Yswitch 56 or 6| as the case may be depending upon whether the operator desires the motor to run vin one direction or the other.

Let us assume that it is desired to energize the motor so that it will run in a forward direction, the operator then closes switch t which completes an obvious circuit through coil F since all of the remaining contactors in that circuit are normally closed by either safety switches or interlock switches. The energization of coil F' therefore causes the F contacts in the power line to close and the motor 22 will rotate in the forward direction.

Transformer H2 and transformer l2@ are now energized and until the tubes e@ and Q2 have heated a predetermined length of time, none of the remainder of the control circuits may be energized. This is due to the fact that electronic thermal switch B8 will not permit the closure of time delay switch contacts 3E.

Since, however, the motor is not clutched to the ram* drive no movement of the latter will be affected. In order to move the ram up into welding position the clutch must be energized. After a suflicient time period has passed to cause the thermionic time delay means S8 to conduct, it closes switch 88 which in turn energizes relay coil L. Assuming further that it is desired to run rather than inch the press, switch i6 is moved to its lower position completing the circuit through relay coil l-I and that is therefore also energized.

This completes a circuit through relay coil A as follows: Power line 45, normally closed switches 62, 64, 63, l'ii, l2, lll, switch Hi, switch R6 which is normally closed when relay coil R is de-energized, a series of switches 9e, coil A to power line 48. As soon as this circuit is completed, a holding circuit for relay coil A is provided through line lill, switches LSI, LS and contactor A2 which is now closed. Referring momentarily to Fig. 2 it will be seen that cam controlled switches l and are closed at this time since the shaded portion of these diagrams begins at the upper or zero position of rotation. Relay coil A being energized, Al is now closed, switch L2 has previously been closed as soon as the time delay contacts are closed as previously described, and switch Ml is closed inasmuch as relay coil M is de-energized- As soon therefore as all the run buttons 9G are depressed by the operators, relay coil B will be energized through an obvious circuit which closes switches Bl and B2 thus completing a circuit through relay coils C and D'. The reason for these two coils being connected in parallel and operated simultaneously is strictly for safety reasons. Thus, if contacts operated by one freeze in, the other will still operate the circuit normally since the contacts operated by the two are always in series and the device will not assume any abnormal operation.

The energization of these two coils C and D opens contactor DI and closes contactors CI, C2, D2, C3, D3, C4, and D4 to complete the power circuit to the clutch coil I3 energizing the same. This magnetically locks the motor to the press drive and the ram begins to ascend since the mechanical brake is also released by the energization of C and E. If the clutch does not become energized, through a tube or brush failure, the series relay S,I does not pick up and consequently the Si contact in series with relay El does not allow the spring set magnetic brake to release. However, if current flows through the S relay the magnetic brake will release simultaneously with the closing of the contacts D3 and C3, C4 and D4 and the press will operate through approximately of rotation on the depression oi buttons 94, at which time cam number 2 operating the LS2 switches will close which by-passes the run buttons 94 which may then be released and the cam LSZ controls the rotation, as shown by the shaded portion in the middle of cam 2 on Fig. 2.

During the time the cam 2 takes over cam l allows its contacts LSI to open cle-energizing relay coil A which provides an anti-repeat operation should the run buttons still be depressed. This permits cam LSZ to control the energization period of coils Cv and D and release them at a predetermined point slightly less than a When these coils are de-energized the magnetic clutch, of course, immediately ceases to drive. Just as the clutch is released the dynamic brake is energized by the closing of the LSA contacts in series with the coils J and K, and acts to bring the moving member to rest. As the ram comes to rest LS@ opens to set the magnetic brake and hold it. Therefore the dynamic brake stops the load and the mechanical brake holds it.

As previously described, the coil H is energized so that switch H3 will be closed and also ccil L has been energized closing contacts L3. Therefore, when cam 4 reaches a predetermined point, Lsg` will close energizing coils J and K which, referring now to the bottom of Fig. 1A, completes an obvious circuit through the dynamic brake coil |40. This combined braking action will bring the press to a stop between dead center and 10 ahead of this point and is controlled by the setting of the cam d. As soon as motion has ceased relay P opens due to the zero speed switch l l E to de-energize the dynamic brake, the mechanical brake holding the device stationary.

In order to insure that the welding is actuated at the proper time it is controlled by the cam switch 5 which is closed only within the desired range. Therefore, the weld initiating relay M is controlled by contact LSE, the zero speed switch relay P and the magnetic brake relay E which, of course, control the operation of switches Eli and P2 in the series circuit, switch H5 being closed as previously described and N2 being normally closed upon coil de-energization as well as E4. The energization of coil M sets the normal welding cycle off and the welding guns are red. To assure that welding pressure will be maintained on the work throughout the welding cycle, the shunt circuit around switch i6 is closed by contactor M2 so that even if switch 7G is accidentally opened the circuit will still be maintained. After the last gun is red a contact in the timer, switch |68, energizes relay N which immediately closes contactor N3 and completes an obvious holding circuit around switch |63 to hold in relay N. vThis also causes switch N2 to open, de-energizing relay coil M, which completes the welding cycle. The energization of relay N also closes switch Nl which by-passes the run buttons and starts the press on the down stroke or last half of the cycle. This completes a circuit for the energization of coil B through line 96, switch NI, switch l, line |22, switch L2, relay coil B and this reenergization of coil B closes contactors BI and B2 to again energize the magnetic clutch coils C and D and in turn the magnetic brake relay E to release that brake.

As previously described, this action clutches the drive motor 22 to the driving means for the press releases the brake and the press begins to descend. After rotation of a-fewsdegrees beyond the welding position, cam 'I assumes control by the closure of cam operated switch LS? to maintain energization of coils C and D, by-passing contactor Ni which initiated the movement. The press continues automatically to movek downward until the clutch is de-energized by the opening of switch LSi slightly ahead of its completion of 360. As the clutch releases the dynamic brake is energized by control or" contact DI or cam 9 Yin its operation through switch LS which by-passes or is in parallel with switch LSfl in the circuit to coils J andK. This dynamic brake remains on until approximately the end of the cycle and the magnetic friction brake sets slightlyA prior thereto through action of camoperated switch LSB. When the press stops, the dynamic brake is released by the zero speed switch H which de-energizes coil P `droppingoutcoils J and K and their associated contacts.

It might be mentioned at this point that there is'a second anti-repeat cam LS@ in serieswith the rst cam LSI to prevent re-energization of coil A1 and thus the continuation ofthe press past the 360 cycle. lf any of the buttonsttl are released during approximately the first 155'of travel, the press will stop by action of the dynamic and Amechanicalbrakes, but if l55is past, cam LSZ takes -over and the press will go through its operation. This operation oi pressing` the buttons of course, is repeated each time itis desired to operate the press Welder;

Assuming now that it is desired to inch the press rather than to drive the same through a full cycle, switch 16 is placed on contact 'i8 for operating position. The press rotation is then directly under the entire control of the manually operated inch button 84 and whenever it is depressed an obvious circuit through relay coils C and D will be completed to energize the clutch s coil 36 and the press will be driven. However, in this case coil H is not energized and the bypass around limiting resistors |38 remains open and the resistors are placed in series with the magnetic clutch 35 to cut down the current ow therethrough to a smaller amount to reduce the flux so that the driving force will be less. Whenever the inch button is relased the brakes will be immediately set. The welding sequence during inching operation will not function since the relay M cannot be energized due to the fact that the contacter H5 remains open. The welding guns however can be actuated manually by the closing of a selector switch on the weld timer which by-passes a switch operated by the coil M (not shown).

If it is desired to operate the motor in the reverse direction the switch 6l instead of switch 56 is depressed and the motor will be rotated in that direction. As soon as switch El is pressed to energize coil R, hold in switch R5 will be closed to maintain the motor operating in this direction. This action also causes switch Re to open, since this is a switch which is normally closed. This opens the circuit for the run buttons 94 and makes them inoperative. The magnetic clutch and solenoid brake can now only be actuated by the inch switch 84, the clutch being energized and the brake released when switch 84 is closed and vice versa when the same is released, since it controls the energization of coils C and D.

We claim:

l. In a control system for a press, a source of power, a motor connectable to said source, rotatable means for driving said press, magnetic iiux clutchmeans between themotorand the rotatable drivingmeans, energizing coils mounted in ,the v,clutch means, dynamic flux brake `means associated with therotatable meansto stop the same, as secondseries of energizing coilsxforthe brake.- means,KVV a f solenoid? released friction brake applicable to the s rotatable means, switching means foricontr-oiling.'the clutch andfbrakes to simultaneously energize thefuX-clutch-and re lease: the friction fbrake land at 'a different time to deenergize thelux clutchl and energize the brakes to stop the rotatablemeansA including al.- ternate' ccntrol means to provide continuous drive for the press through an` operating cycle orfto movef" at small distances as desired, and additional switching meansin a shunt circuit to thealternatefcontrol means to maintain a continuousv circuit through a given portion of the cycle once it has been started.

2. ln a control system for a press, a source `of power, a motor connectable to said source, rotatable means for driving said press, magnetic flux-clutch means'between the motor and the rotatable driving means,l energizing coils mounted in the clutch means, dynamic flux brake means associated with the rotatable means to stop the same, a second series of energizing coils for the brake means, a solenoid released friction brake applicablel to the rotatable means, switching means for controlling 'the clutch and brakes to simultaneously energize the flux clutch andreie'ase'the friction brake and at a different time to deenergize the flux clutch and energize the brakes to stop the rotatable means, a master switch controlling the first-named switching means for continuous operation for a cycle of the press, a shunt circuit around the master switch, and additional switching means in the shunt circuit to close the same during a portion of the cyclic operation to assure continued operation of the press even though the master switch may be opened.

3. In a control system for a cyclically operating press machine, a source of power, driving means connectable to said source, operating means for the press, magnetic flux clutch means between the driving means and the operating means, dynamic flux braking means applicable to the operating means, mechanical solenoid brake means applicable to the operating means, switching means for controlling the clutch and brakes to initially energize the iluX clutch and emove the magnetic brake at the beginning of a cycle in moving from a position of rest, energize the ux brake, deenergize the flux clutch and apply the friction brake when the press is in clamping position at an intermediate portion of the cycle, further switching means actuated at the termination of the clamping portion of the cycle to again cause actuation of the rstnamed switching means to energize the flux clutch and remove the friction brake to return the apparatus to a position of rest, and a holding circuit for the further switching means to assure return to the rest position.

4. In a control system for a press, a source of power, a motor connectable to said source, rotatable means for driving said press, magnetic ux clutch means between the motor and the rotatable driving means, energizing coils mounted in the clutch means, dynamic flux braking means and mechanical solenoid braking means applicable to the operating means, energizing coils in the ux braking means, combination relay and cam controlled switching means toenergize the iiux clutch coils and remove the friction brake to cause the press to move from a position of rest to a position slightly in advance of the clamping position and then deenergize the iiux clutch, energize the flux brake and then apply the friction brake to stop the press in clamping position to perform work on a clamped part, additional switching means acutated by the completion of the acts performed upon the clamped part to cause the clutch and brake control switching means to recycle to bring the press back to a position of rest, and locking means for the additional switching means to assure return to the rest position.

5. In a control system for a press having a platen that moves from a position of rest to full clamping position to clamp work members upon which acts are to be performed and then returned to rest position, a source of power, a motor connectable to said source, rotatable means for driving the platen, magnetic flux clutch means connected between the motor and the rotatable driving means to couple the same, magnetic iiux brake means applicable to the rotatable means and solenoid friction brake means applicable to the driving means, switching means connected between the source of power and the magnetic ux clutch and brake and solenoid brake to energize and deenergize same in time relation to move the platen to clamping position, hold it there for a predetermined time until acts have been performed on the Work members and then move said platen back to a position of rest, said initiation of the movement back to rest position provided by the completion of the acts performed upon the work and locking means to maintain operation until the platen has returned to rest.

WILLIAM DE LOHR BERRY.

STERLING G. VIGARS.

WILLIAM E. ADAMEK.

REFERENCES CITED The followingreferences are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 744,423 Steckel Nov. 17, 1903 844,661 Cutler Feb. 19, 1907 1,217,244 Turbayne Feb. 27, 1917 1,259,861 Henry Mar. 19, 1918 1,993,413 Mellon Mar. 5, 1935 2,018,720 Hodgson Oct. 29, 1935 2,021,173 Clark Nov. 19, 1935 2,071,473 Roth Feb. 23, 1937 2,085,442 Newell June 29, 1937 2,151,734 Bouton et al. Mar. 28, 1939 2,185,551 Glasner et al. Jan. 2, 1940 2,323,696 Weightman July 6, 1943 2,333,863 Hull Nov. 9, 1943 2,340,655 Fotie Feb. 1, 1944 2,411,122 Winther Nov. 12, 1946 2,462,747 Jacobs Feb. 22, 1949

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