US2471505A - Punch press - Google Patents

Description

May 31, 1949. J. B. WINTHER 2,471,505

PUNCH PRESS Filed Jan. 4, 1947 4 Sheets-Sheet 1 FIG. 4.

C COUPLING ELECTRIC BRAKE I l J MECHANICAL BRAKE T FIG. 5.

1 wyisgw y 9- J. B. WINTHER 2,471,505

ruucn PRESS Filed Jan 4, 1947 4 Sheets-Sheet 2 FIG. 2.

1949- J. B. WINTHER 2,471,505

PUNCH PRESS Filed Jan. 4, 1947 4 Sheqts-Sheet a FIG. 3.

1 37 A4 L 133 M7 u 135 137 T 14; A r39 b gi y 1949. .1. B. WINTHER 2,471,505

PUNCH PRESS Filed Jan. 4, 1947 -4 Sheets-Sheet 4 Patented May 31, 1949 PUNCH PRESS Jerrold B. Winther, Kenosha,

Martin P. Winther, as

Wis, assignor to trustee Application January 4, 1947, Serial No. 720,256 Claims. (Cl. 172-284) This invention relates to presses, and more particularly to punch presses for punching or forming operations.

Among the several objects of the invention may be noted the provision of an improved, electrically-controlled press, such as a punch press or the like; the provision of a press of this class wherein heavy-current contacts are eliminated from inductive circuits of the electrical control to eliminate arcing across and failure of contacts due to inductive kick; the provision of a press of the class described which may readily be selectively operated to run through one full-stroke operating cycle and stop, or to run continuously, or to inch in either direction; and the provision of such a press which is inexpensive to operate and maintain. Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

Fig. 1 is a simplified, diagrammatic skeleton layout of the press of the invention;

Fig. 2 is an enlarged detail longitudinal section through a flywheel, slip coupling and brake assembly, shown diagrammatically in Fig. 1;

Fig. 3 is an electrical circuit diagram with switches set in neutral positions;

Fig. 4 is a developed diagrammatic view of a group of cam-operated switches associated with the press;

Fig. 5 is an enlarged view of a portion of the electrical circuit, illustrating a master selector switch; and

Fig. 6 is a diagram like Fig. 3, except that the switches are set for the 170 position during singlecycle operation.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

This invention is an improvement upon the press disclosed in the copending and coassigned application of Martin P. Winther for Press, Serial No, 704 552, filed October 21, 1946. That application discloses a press, the drive for which includes an inductive eddy-current slip coupling and an inductive eddy-current brake. The inductive field coils of the coupling and brake are in a rectifier circuit which supplies current thereto under the immediate control of relays, the contacts of which are directly in the field coil circuits. As these relays open, inductive current kick tends to cause arcing across their contacts. Such areing tends to reduce the life of such contacts. The protection for the contacts illustrated in said copending application is effective to a certain extent, but this invention has for its purpose the provision of a press of the type disclosed in said copending application embodying an improved circuit for energizing the field coils of the coupling and brake wherein there are no relay contacts subject to failure due to inductive kick. It thus reduces maintenance troubles from such a source.

Referring now more particularly to Fig. 1, there is shown at I the slide or ram of a press, which may be a punch press for punching or forming metal or the like. The ram is linked by a connecting rod 3 to the crank or eccentric 5 of a crankshaft or ram shaft 1. The crankshaft is driven from a drive shaft 3 through speed-reduca stationary braking field member 29.

l of cam-operated switches 31, 39 and ing gears II and I3. The drive shaft 9 is driven by a motor l5 through an electromagnetic eddycurrent slip coupling ll. This couplin includes a driving field rotor l9 and a driven inductor member 2|. The field rotor is formed as a pulley and is driven by V-belts 23 from a pulley 25 on the shaft of motor l5. The field rotor is mounted upon a flywheel 21, which is rotary on the end of drive shaft 9. The inductor member 21 is adapted to be decelerated electromagnetically by This brakes the drive and crankshafts. The crankshaft is also under the control of a mechanical brake 3| and is coupled by a 1:1 ratio chain and sprocket drive 33 to the camshaft 35 of a group 4 l the function of which will be described subsequently.

Details of the flywheel, electromagnetic clutch and electromagnetic brake assemblies are shown in Fig. 2. As illustrated, flywheel 21 has a hub 41 journalled by roller bearings 49 on the end of the drive shaft. The field rotor is includes a hollow ring-like structure secured to the flywheel by screws 5| and formed with peripheral grooves 53 to receive the belts 23. Within the hollow ring-like structure are two annular field coils 55. The ring structure is formed internally with a series of peripherally spaced and axially lapped magnetic pole teeth 51, which are broadly similar to those described in U. S. Patent 2,367,636, dated January 16, 1945. The field coils are energized from wires 55 and 6| through slip-ring connections 63. When energized, the coils induce mag- I indicated at 69. Two copper end rings H and 13 are attached to the ring 65 to reduce the resistance to flow of eddy currents therein, in the manner described in coassigned, copending application of Martin P. and Anthony Winther, Serial No. 684,112, filed July 1'1, 1946, for Electromagnetic coupling. When the field ,coils 55 of rotor I9 are energized and the rotor driven by motor I5, the inductor member 65 has eddy currents engendered therein and is driven by magnetic reaction. This rotates drive shaft 9. The degree of coupling is a function of the excitation of coils 55.

The braking field member 29 comprises a hollow ring structure 15 secured by screws 19 to the press frame 11. This ring structure, disposed within the inductor ring 65, is formed with alternate oppositely directed pole teeth 8| similar to teeth 51 above mentioned, except that they extend outward towards the inside of the inductor 65. An annular field coil 83 disposed in the hollow ring structure is adapted to be energized by wires 85 and 81. When energized, coil 83 induces magnetic poles in pole teeth 8| to brake the inductively related inductor member 2! by magnetic reaction, according to the excitation of coil 83.

It will be clear from the above description that when the motor I5 is energized to drive the field rotor I9 and flywheel 21, and the coils 55 are energized, the drive shaft 9 will be driven through the slip coupling and will drive crankshaft 1 to reciprocate the ram. When coils 55 are deenergized, and the coil 83 of the braking field is energized, the drive shaft will be braked to stop rotation of the crankshaft and hence to stop the ram.

The invention includes means whereby the operator may readily selectively control the press, through control of the motor 15, the electromagnetic clutch and brake and the mechanical brake 3|, to run through one full stroke or cycle of the ram (one revolution 01 crankshaft 1) and then automatically stop, or to cycle continuously without stopping between cycles, or to inch, which means to creep by small increments through any portion of a cycle in either direction. This selective control is effected by means of a master selector switch S (Figs. 3 and 5).

The switch S includes three pairs or contacts S-I, S-2 and S-3 and two contactor bars III and 93 on a push-pull rod 95. Contactor bar 9| is cooperable either with contacts S-I or 8-2. Contactor bar 93 is cooperable with contacts 8-3. In one end position of rod 95, bar 9I bridges contacts S-l. This conditions the press for operation through one full-stroke cycle and then to stop. This position is indicated in full lines in Fig. 5 and by the pointer 91 on rod 95 being aligned with an index mark designated Single cycle. In the other end position of rod 95, bar 9| bridges contacts 8-2 and bar 93 bridges contacts S-3. This conditions the press to operate continuously without stopping between cycles. This position is indicated in dotted lines in Fig. 5 and by the pointer 91 being aligned with an index mark designated Continuous. In an intermediate position of rod 95, contacts 8-1, 8-2 and S- -3 are open. This conditions the press for inchingat slow speed through any part or a cycle. This position is indicated in Fig. 3 and in dot- 4 dash lines in Fig. 5 and by the pointer 91 being aligned with an index mark designated Inc The manner in which such control is effected will be developed below. 4

Motor I5 is reversible and is energized for driving drive shaft 9 in one direction or the other by any suitable control circuit, for example, the motor control circuit illustrated in the aforesaid copending application Serial No. 704,552.

The field coils 55 and 83 of the field rotor I9 and braking field member 29, respectively, are adapted selectively to be energized by means of direct current supplied thereto by a direct current reversible pole generator IIll driven at constant speed by an induction motor I03 or any other suitable prime mover (Fig. 3). Coils 55 are connected in a line I05 across the output leads I81 and I59 of the generator. It will be understood that line I05 includes the aforesaid wires 59 and BI (Fig. 2). This line also includes an electric valve III, such as a copper oxide rectifier or the like, which permits current to fiow in line I05 and coils 55 only when output lead I91 is at a higher potential than lead I99. Coil 83 is connected in a line I13 across leads I01 and I09, this line including an electric valve I I5 which permits current to flow in line H3 and coil 83 only when output lead I89 is at a higher potential than lead I81. It will be understood that line H3 includes the aforesaid wires 85 and 81 (Fig. 2).

The generator "II is excited by a separate field II1. This field is in a circuit embodying controls for supplying rectified current to flow through the field in one direction or the other so as to reverse the polarity of the generator. The arrangement is such that upon flow of current from field terminal II9 through field II1 to its other terminal I2I, the polarity of generator IN is such that current flows from lead I01 to lead I09 in line I85 including coils 55 through valve III. Line II3 including coil 83, however, is blocked by valve H5, and coil 83 is deenergized. Upon reverse flow of current in the generator field II1 (from field terminal I21 through II1 to terminal II9), the polarity of the generator is reversed, and current flows from lead I89 to lead I01 in line II3 including coil 83 through valve.

II5. Under these conditions, line I05 including coils 55 is blocked by valve III, and coils 55 are deenergized.

Direct current for the supply of generator field I I1 is derived from a bridge rectifier I23, the input of which is fed by the secondary I25 of a transformer T. The primary I21 of this transformer is connected across power leads I29 and I3I of a two-wire single phase alternating current system. The power supply is under the control of switches I33 and I35 and fuses I31 and I39 in these leads. Power leads I29 and I3I are also adapted to energize a plurality of relay coils A, B, C, D, E, F and G, each of which controls certain contacts associated therewith in a manner to be described. It is to be understood the D. C. source for the generator field II1 need not be a rectifier but may assume other forms such as a D. C. exciter or battery.

Relay coil A is connected across leads I29 and I3I in a line I4I including a normally closed push button stop switch I43 and the upper contacts of a double-pole push button control switch I45. The switch I45 is biased so that its upper contacts in line I4I normally are closed. Coil A when energized closes contacts A-I' and A-2. Contacts A-I are in a line I41 shunted around the upper contacts of switch I45 including cam-operated switch 31. ,When coil A is energized, contacts A-I are closed and this shunt functions as a holding circuit for coll A as long as cam-operated switch 31 is closed, whereby switch I45 may be operated without decnergizing coil A..

Relay coil B is connected in parallel with coil A in a line I49 including the lower contacts of control switch I45 and contacts A-'2 and in series with switch I43. This coil B when energized closes contacts BI and B2. Contact BI is in a line III shunted around the lower contacts of control switch I45 and contacts A-2. This line also includes the cam-operated switch 39. A line I53 shunted around switch 39 includes contacts 8-3 oi the master selector switch S.

Relay coil C is connected in a line I55 across power leads I29 and I3I including c'ontacts'S2 of the master selector switch. This coil when energized closes normally open contacts C--I, C-3 and C-4, and opens normally closed contacts C--2, all oi which are associated with the coil C for group operation, Contacts C4 are in the rectifier circuit for supplying direct current to generator field H1, as will be described. Contacts C-I are in a. line I51 connecting line I5I and a line I59. Line I51 also includes contacts B-2 operatedby relay coil B. Line I59 is connected across power leads I29 and III and includes a normally open push button inching control switch I90, contacts C--2, and relay coil D. A line I9I shunted around contacts S-2 includes contacts S-I of the master selector switch S.

Relay coil D when energized. closes normally open contacts DI, D3 and D-4 and opens normally closed contacts D2, all associated therewith for group operation. Contacts D3 and D4 are in the generator field circuit, as will be made clear,

Relay coil E is connected in a line I63 across power leads I29 and I3I including contacts C-3 and cam-operated switch 4I. This coil when energized closes contacts EI in a line I65 connected across power leads I29 and I3I' and including a solenoid coil I91. This solenoid coil is a control solenoid for the mechanical brake 3|. When the solenoid is energized, the brake is released. The linkage through which the solenoid releases the brake is not shown, bein of any suitable conventional form. A line I69 shunted around contacts 0-3 and cam-operated switch 4I includes contacts D--I operated by relay coil D.

Relay coil F is connected in a line "I connected across power leads I29 and I3I and includes normally closed contacts D2 and normally closed contacts GI operated by a timedelay relay coil G. This coil G is connected in a line I13 shunted around contacts GI and coil F and when energized opens contacts GI after a predetermined time interval for a purpose to be described, Coil F when energized closes contacts FI and F2 in the generator field rectifier circuit.

The generator/field rectifier circuit includes a supply line I15" connecting the negative output terminal of bridge rectifier I23 and a terminal I11. From terminal I11 a supply line I19 including contacts D3 and a resistor I9I connects to generator field terminal I I9. Also, from terminal I11 a line I93 including contacts F-I connects to generator field terminal I2I. Contacts 0-4 are in a shunt I95 around resistor I9I. A line I91 including contacts F2 connects line I19 and a terminal I99. A line I9I including contacts D-4 connects line I93 and terminal I99. A line I93 connects terminal I99 to the positive output ter- 6 minal oi. the bridge rectifier. A protecting resistance I and condenser I91 are connected in a line I99 in parallel with generator field II1.

As illustrated in the development 0! Fig. 4, the cams for the cam-operated switches are so designed and phased as to maintain switch 31 closed for the first 205 oi the cycle of the crankshaft 1 and the press ram, to reopen this switch over the portion of the cycle between 205 and 240, and to reclose this switch over the remainder of the cycle (240-360). The cam for switch 39 opens this switch for the first of the cycle, recloses it from 170 to 290, and reopens it from 290 to 360. The cam for switch 4I closes the switch for 325 of the cycle, and reopens it during the remainder.

' Operation is as follows:

Assuming that motor I5 and belts 23 are driving the field rotor I9 and that motor I03 is driving the generator IOI, switches I33 and I35 are closed to supply power to the A. C. power leads I29 and III (Figs, 3 and 6). To operate the press for a single cycle (one reciprocation oi the press ram and return), the master selector switch is set in the single cycle" position wherein contacts S-I are closed. This completes a circuit through line I55, shunting open contacts S2 through line I9I, and energizes relay coil C. Energization of coil C closes associated contacts C-I, C-3 and C-4, and opens normally closed contacts C-2.

At the start of a cycle, cam-operated switches 31 and H are closed and cam-operated switch 39 is open Fig. 4). Later at 170 of operation switch 39 closes and this latter condition is shown in Fig. 6. Referring again to the beginning of the cycle at 0, stop switch I43 and the upper contacts of control switch I45 are closed and a circuit through line I4I including coil A is completed. It will be understood that Fig. 6 shows a later condition at 170 so far as switch I45 is concerned. Energization of coil A closes contacts A-I and A2. With switch 31 and contacts A-I closed, a holding circuit shunted around the upper contacts of switch I45 is completed through line I41 to maintain coil A energized when switch I45 is operated.

With contacts 0-3 and cam-operated switch 4I closed as stated, a circuit is completed through line I53 and coil E. Energization of coil E closes contacts E--I in line I65 and completes a circuit through solenoid coil I61. This coil thereupon releases the mechanical brake 3I to permit crankshaft 1 to rotate.

To start the cycling of the press, the operator presses in on control switch I45 to close its lower contacts. This completes a circuit through line I49 and coil B. the lower contacts of switch I45 and contacts A-'2 in this line being closed. Coil A remains energized through the holding circuit I41. Energization of coil B closes associated contacts BI and B2. Contacts CI are already closed, as previously described. A circuit through relay coil D is thereupon completed from power lead I29, through part of line I 4|, part of line I49, line I5I, line I51 and line I59 (including coil D) to the other power lead I3I. Energization of coil D closes contacts DI, D3 and D-4, opens normally closed contacts D2. Closure of contacts DI establishes a holding circuit through line I69 around contacts C-3 and cam-operated switch 4|. Opening of contacts D2 breaks the circuit through line I1I including coil F. The resultant deenergization of coil F opens contacts F-I and F-2 in the generator field rectifier circuit. Of course when there is a delay in actuating the switch I 45 after energization of power leads I29 and I3I, the time-delay relay G operates to open switch G-I and deenergizes coil F. Closure of contacts D3 completes a supply circuit from the negative output terminal of the bridge rectifier to the generator field terminal II9 through line I15 to terminal I11, and line I19, with resistor I8I shunted out by line I85 including presently closed contacts C-l. Closure of contacts D4 completes 'a return circuit from generator field terminal I2I through a portion of line I83, line I9I including closed contacts D I, terminal I89 and line I93 to the positive output terminal of the bridge rectifier. Rectified current from bridge rectifier I23 thereupon flows from terminal H9 through generator field II! to terminal I2I.

Generator field III thereupon excites the generator so that it generates direct current with its polarity such that line I01 is at a higher potential than line I09. Current thereupon fiows through valve III and the coupling field coils 55. Current flow through braking field coil 83 is blocked b valve H and the braking field member 29 is deenergized.

With the coils 55 of field rotor I9 energized as above described, the press is driven from the motor I5 and flywheel 2! through the slip coupling to perform the punching, forming or like operation. The operator retains control switch I45 pressed in to keep its bottom contacts closed until the press has cycled through at least 170". At 170', cam-operated switch 39 closes (Fig. 4). The operator may now release control switch I45.v This opens its bottom contacts, but since switch 39 is now closed, shunt holding circuits are provided to maintain relay coils B and D energized. The holding circuit for coil B is through line I5I including closed switch 39 and contacts B-I. The holding circuit for coil D is through line I5I including closed switch 39 and line I51 including closed. contacts 13-2 and C-I. Fig. 6 shows the switch positions at this stage in the single-cycle operation. It also shows by arrows at the lower right how current is flowing at this stage.

The coils 55 continue to be energized to drive the press until the press has cycled through 290, whereupon cam-operated switch 39 opens. Since the operator has released control switch I45, its bottom contacts are open. With these bottom contacts open and switch 39 open, the circuits for coils B and D are open. Upon deenergization of coil D, contacts DI, D3 and D4 open; contacts D-2 close. Upon closure of contacts D2, a circuit is completed through line I" including closed contacts D-2 and G-I and coil F. Energization of coil F closes contacts FI and F-Z in the generator field rectifier circuit. Closure of contact FI completes a supply circuit from the negative output terminal of bridge rectifier I23 to the generator field terminal I2! through line I to terminal I" and thence through line I83 (including closed contacts FI). Closure of contacts F2 completes a return circuit from generator field terminal II9 through a portion of line I19, line I91 (including closed contacts F-2), terminal I89 and lin I93 to the positive output terminal of the bridge rectifier. Rectified current thereupon flows from terminal I2I through generator field II! to terminal II9.

Generator field III thereupon excites the generator so that it generates direct current with its polarity such that line I09 is at a higher potential than line I01. Current thereupon flows through valve I I5 and the braking field coil 83. Current flow through coupling field coils 55 is blocked by valve III and the electromagnetic clutch is deenergized.

With coil 83 energized, braking field member 29 is energized to exert a braking action on the inductor member 2|. This occurs without any substantial overlap between electric clutch and brake actions (see Fig. 4). At 325 in the cycle of the press, cam-operated switch 4I opens (Fig. 4). This breaks the circuit of relay coil E, whereupon contacts E-I open and break the circuit of solenoid coil I61. This applies mechanical brake 3|, and the combined braking action of the electromagnetic brake and the mechanical brake brings the press to a stop after it has cycled through 360 back to its initial position at 0".

If the operator should fail to release control switch I45, the press is prevented from repeating the cycle by the action of cam-operated switch 31. This switch opens at 205 in .the cycle and breaks the holding circuit I 41 for coil A. If switch I45 is pressed down at this time, its upper contacts will be opened and cell A deenergized. This opens contacts A-I and A-2. Coils B and D remain energized through line I5| including cam-operated switch 39 as long as this switch is closed, but when this switch opens at 290, as previously described, coils B and D are deenerglzed to deenergize the electromagnetic clutch and apply the brake to stop the press after one cycle. Thus, there is provided an anti-repeat means to prevent repetition of the cycle when the selector switch is set for single cycle operation should the operator inadvertently fail to release push button switch I45 or repress this switch after having released it.

After the press comes to a stop, relay coil F continues to be energized until time-delay relay G is energized after lapse of a predetermined period of time (of the order of 30 seconds) to open contacts G-I and deenergize coil F. This opens contacts F-I and F2 to deenergize generator field II 'I and braking field coil 83 in the interests of economy.

To operate the press continuously, without stopping between cycles, the master selector switch S is set in the "continuous position wherein contacts S2 and S3 are closed, as illustrated in dotted lines in Fig. 5. Closure of contacts H completes the circuit through coil C with resultant closure of contacts C-I, 0-3 and C-4 and opening of contacts C2. Closure of contacts S-3 completes the shunt circuit through line I53 around cam-operated switch 39. To start continuous operation of the press, the operator pushes in control switch I45 to close its bottom contacts. This energizes relay coils B and D, as previously described, and closes contacts DI, D3 and D--4. opening contacts DZ.

Closure of contacts DI completes the shunt I69 around cam-operated switch II so that coil E is continuously energized, despite opening of switch 4|, to maintain contacts EI closed and solenoid coil I61 continuously energized. This continuously maintains the mechanical brak 3| released.

Opening of contacts D-2 deenergizes coil F so that contacts F-l and F-2 are continuously open. Closing of contacts D3 and D-4 completes the circuit for generator field H1 in such manner that current flows through the field from terminal II9 to terminal I2I. This results in I from power lead I29 to lead I3I energization of coupling field coils 55 and deenergization of braking field coil 33 as previously described. With coils 55 energized, the electromagnetic clutch is energized so that the press is driven.

The operator maintains switch I45 pressed in until the press comes up to speed and may then release it. Even though the bottom contacts of this switch are open, coils B and D remain energized through the shunt circuit including line I and line I53, since line I53 includes closed contacts S--3 of the master selector switch. The cam-operated switch 39 has no effect on coils B and D since it is shunted out by the line I53 including closed contacts S3. The press continues to cycle until stop switch I43 is operated to break the circuit for coil B. Thus, during continuous operation of the press, the slip coupling I1 is continuously energized. The mechanical brake 3| is released and braking field coil 83 is deenergized so that there is no braking of crankshaft 1.

To operate the press at very slow inching speed through a portion of the stroke of the ram, the master selector switch is set in the inch position, as illustrated in dot-dash linesin Fig. 5, wherein all of the contacts S I, S-2 and 8-3 are open. Thus, coil C is deenergized, and its contacts C-I, C-3 and 0-4 are open, contacts 0-2 closed. With C-2 closed, inching control switch I60 may be closed to complete a circuit through line I59 and relay coil D. Upon resultant energization of coil D, its contacts D--I, D--3 and D-4 close, contacts D-2 open. With D-I closed, coil E is energized, contacts E-I close and complete the circuit for solenoid coil I61 to release the mechanical brake 3|. With D-2 open, coll F is deenergized to open contacts F-I and F-2. With D3 closed, a supply circuit for generator field I I 1 is established put of rectifier I23 to generator field terminal I I9 through line I15 to terminal I11, thence through line I19 including closed contacts 13-3 and resistor I8I. Contacts C4 are open so that this resistor is not shunted out. With 0-4 closed, a return circuit is established from generator field terminal I2I through line I33, line I9I including closed contacts D-l, terminal I89 and line I93 to the positive output terminal Of the rectifier I23.

Rectified current from rectifier flows from terminal II9 through generator field II1 to terminal I2I. This current is relatively weak due to the resistor I8I now in the circuit. The resultant low excitation of generator IIII by its field II1 causes a relatively weak current to flow through coupling field coils 55. Braking field coil 83 is deenergized, as previously explained. The result is that the slip coupling I1 drives the drive shaft 9 with low torque and considerable slip so that the press is driven very slowly for inching operation. The press is driven as long as switch I90 is closed. Inching in reverse direction may be accomplished by reversing the motor I5. This inching operation is not intended for power punching or forming but for fine adjustments of the ram I required for setting and aligning dies and the like.

Thus, the coils 55 of the electromagnetic slip coupling and the coil 33 of the electromagnetic brake are adapted to be selectively energized merely by reversal of the polarity of .the source of current for the coils, i. e., the generator IIII. There are no current contacts in the circuit for I23 thereupon from the negative terminal outand means in said 10 the coupling and braking coils subject to failure due to arcing caused by inductive kick. The press may be readily selectively energized .to run through one full-stroke operating cycle and stop, or to run continuously, or to inch according to the setting of master selector switch S.

In view of the objects of the invention, it may be questioned that switches such as D-3, D-4, F-I and F-2, are in a D. C. circuit involving inductive coils which may be presumed to kick current across the switches when the circuit is broken. It should be noted, however, that every switch in this category is in a circuit in which the inductive coil H1 is relatively small and the arcing effects of which may readily be minimized in the usual way by means of the by-pass I91, I95. The case of the coils 5i and 33 is different, since these must necessarily have a large number of ampere turns to produce suilicient field for the coupling and brake effects on the inductor 65 and it would not be feasible to produce a by-pass construction large enough.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A press comprising a ram, means for reciprocating the ram including a rotary ram shaft, means for driving the shaft including an electromagnetic inductive coupling having a coupling field coil, an electromagnetic inductive brake for braking said shaft having a braking field coil, a reversible pole generator, 9. connection across the output of said generator including said coupling coil and an electric valve permitting current flow through said coupling coil only when said generator is of one polarity, a parallel connection across said generator output including said braking coil and an electric valve permitting current flow through said braking coil only when said generator is of opposite polarity, and means coordinated with the motion of the ram shaft for reversing current flow in the field of said generator for reversing its polarity.

2. A press comprising a ram, means for reciprocating the ram including a rotary shaft, means for driving the shaft including an electromagnetic slip coupling having a coupling field coil, an electromagnetic brake for braking said shaft having a braking field coil, a generator, a connection across the including said coupling coil and an electric valve permitting current flow through said coupling coil only when said generator is of one polarity, a parallel connection across said generator output including said braking coil and an electric valve permitting current flow through said brakin coil only when said generator is of opposite polarity, a separate field for said generator, a rectifier circuit for energizing the generator field, circuit for reversing current flow in said field for reversing the polarity of the generator.

3. A press comprising a rain, means for reciprocating the ram including a rotary ram shaft, means for driving the shaft including an electromagnetic inductive coupling having a coupling field coil, an electromagnetic inductive brake for braking the shaft and having a braking field coil,

output of said generatorv a reversible pole generator having an exciting field coil, a connection across the output of said generator including said coupling coil and an electric valve permitting current flow through said coupling coil only when said generator is of one polarity, a parallel connection across said generator output including said braking coil and an electric valve permitting current flow through said braking coil only when the generator is of opposite polarity, a reversible D. C. circuit for reversing current flow in the generator field coil for reversing the polarity of the generator, control elements in said reversible D. C. circuit adapted initially to establish one polarity of said field coil thereby to apply torque through the coupling to said shaft to reciprocate the ram, and circuit elements coordinated with the ram shaft and operating in phased relation to part of a revolution of the ram shaft adapted automatically to reverse said polarity of the field coil after the ram has passed mid stroke, thus without overlap automatically to deenergize said coupling coil and to energize said brake coil automatically to decelerate the press electrically during a single cycle.

4. A press comprising a ram, means for reciprocating the ram including a rotary ram shaft, means for driving the shaft including an electromagnetic inductive coupling having a coupling field coil, an electromagnetic inductive brake for braking the shaft and having a braking field coil, a reversible pole generator having an exciting neld coil, 2. connection across the output of said generator including said coupling coil and an electric valve permitting current fiow through said coupling coil only when said generator is of one polarity, a parallel connection across said generator output including said braking coil and an electric valve permitting current flow through said braking coil only when the generator is of opposite polarity, a reversible D. C. circuit for reversing current flow in the generator field coil for reversing the polarity of the generator, control elements in said reversible D. C. circuit adapted initially to establish one polarity of said field coil thereby to apply torque through the coupling to said shaft to reciprocate the ram, circuit elements coordinated with th ram shaft and operating in phased relation to part of a revolution of the ram shaft adapted automatically to reverse said polarity of said field coil after the ram has passed mid stroke, thus without overlap automatically to deenergize said coupling coil and to energize said brake coil automatically to decelerate the press electrically during a single cycle, and selector elements for selectively connecting said phased elements for single-cycle accelerating and declerating operation of the ram or for shunting said phased elements for con- .tinuous operation of the ram under one polarity of the generator.

5. A press comprising a ram, means for reciprocating the ram including a rotary ram shaft, means for driving th shaft including an electromagnetic inductive coupling having a coupling tric valve permitting current fiow through said coupling coil only when said generator is of one polarity, a parallel connection across said generator output including said braking coil and an electric valve permitting current flow through said braking coil only when the generator is of oppositepolarity, a reversible D. C. circuit for reversing current flow in the generator field coil for reversing the polarity of the generator, control elements in said reversibl D. C. circuit adapted initially to establish one polarity of said field coil thereby to apply torque through the coupling to said shaft to reciprocate the ram, phased circuit elements coordinated with the ram shaft and operating in phased relation to part of a revolution of the ram shaft adapted automatically to reverse said polarity of said field coil after the ram has passed mid stroke, thus without overlap automatically to deenergize said coupling coil and to energize said brake coil automatically to decelerate the press electrically during a single cycle, selector elements for selectively connecting said phased elements for singlecycle accelerating and decelerating operation of the ram or for shunting said phased elements for continuous operation of the ram under one polarity of the generator, and inching control means operative continuously at one polarity of the generator adapted to reduce .current from the generator to cause said coupling to operate at low torque to reciprocate the ram at low inching speed.

JERROLD B, WINTHER.

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

UNITED STATES PATENTS

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