US3043271A - Control system for impact device - Google Patents

Description

CONTROL SYSTEM FOR IMPACT DEVICE Filed March 10, 1961 4 Sheets-Sheet 1 FIG. I.

INVENTORS:

WILMER W. HAGUE GLENN A. HOUSEHOLDER AT TVY 5s.

July 10, 1962 w. w. HAGUE ETAL 3,043,271

' CONTROL SYSTEM FOR IMPACT DEVICE WlLMER W. HAGUE GLENN A. HOUSEHOLDER ATTYS.

July 10, 1962 w. w. HAGUE ETAL 3,043,271

CONTROL SYSTEM FOR IMPACT DEVICE Filed March 10, 1961 j 4 Sheets-Sheet 3 FIGS.

INVENTORSI MER W. HAGUE WIL GLENN A. HOUSEHOLDER av J W ATTYS:

July 10,

W. W. HAGUE ETAL CONTROL SYSTEM FOR IMPACT DEVICE Filed March 10, 1961 FIG.4

4 Sheets-Sheet 4 INVENTORSZ WILMER W. HAGUE GLENN A. HOUSEHOLDER ATTYS.

its tates This invention relates to a stroke programmer control system for an impact device having means permitting selection of strokes of more than one length.

It has become common in impact devices, such as drop hammers and horizontally opposed ram impacters, to provide more than one stroke length. Means for accomplishing variation in stroke length may take different forms depending on the nature of the machine controlled. For example, a stroke length control for a drop hammer is taught in US. Patent 2,604,071 to Paul A. Rickrode, assigned to the assignee of the present invention. FI'B'. quently two stroke lengths are provided, but more than two stroke lengths may be provided by a reasonable extension of the known techniques, such as the arrangement shown in the Rickrode patent. In any event, there will be provided at least one stroke length selector means which may have alternate positions for different stroke lengths and there may be separate selector means for each possible stroke length. The nature of the stroke length selector means may vary depending upon the type of impact device employed, as Well as the techniques of actuating and operating that device.

For various reasons, a particular pattern or sequence of blows is usually found desirable in connection with work of a given kind. Usually, there are a certain number of blows of one stroke length and then a certain number of blows of another stroke length, etc. Very frequently short strokes precede long strokes but this is not always the case. Whatever preferred pattern of strokes has been selected, it has been necessary, heretofore, once the sequence of blows has been determined for the operator to remember the sequence and manually select the length of each stroke. This has been a tedious job and in some instances operators lose count of the precise number of strokes of a given length which have been applied or even the sequence 'of stroke group if a complicated pattern is involved and thereby depart from the optimum sequence of blows.

In accordance with the present invention, means is provided for programming or pre-selecting the number of blows of a given stroke length in a particular sequence. In some embodiments of the invention, it is even possible to vary the order of stroke length as desired. Once the stroke program is selected the control system, each time it is actuated, and until the programming is changed will cause the controlled impact device to follow its pre-selected program of strokes. Y

In accordance with the present invention, the stroke programmer control system consists of counting means for counting strokes of the impact device, at least one means for actuating each of the stroke length selector means and sequencing means responsive to the counting means associated with at least one less than the total number of actuating means to terminate a sequence of strokes of a particular length at a selected count and initiate a sequence of strokes of another predetermined length.

For a better understanding of the present invention, reference is made to the following drawings in which a pressure fluid actuated gravity drop hammer is shown in connection with the stroke programmer control system of the present invention and in which:

FIG. 1 is a front elevational view partly in section of atent ice the drop hammer together with a cabinet for controls and circuitry of the control system of the present invention;

FIG. 2 is a simplified schematic circuit diagram illustrating the primary components of the system and their coaction;

FIG. 3 is a more complete circuit diagram of a practical system for the system shown in simplified form in FIG. 2; and V FIG. 4 is an other simplified circuit diagram showing means for programming and controlling more than two stroke lengths the sequence of which may be varied.

Referring particularly to FIG. 1, the present invention is shown in conjunction with a fluid pressure operated drop hammer comprising the usual base 1, relatively spaced apart side frames 2 and a head or upper housing 3 which mounts a vertically arranged cylinder 4 for containing a piston 5. Piston rod 6 has its upper end connected to the piston 5 and its other end is connected to a ram 7 which is mounted for vertical reciprocatory movement between the side frames 2 and adapted, when dropped, to cooperatively engage the usual anvil Ssupported upon the base 1 of the apparatus.

In accordance with the practice usually employed in pressure fluid operated drop hammers, the ram 7 is adapted to drop freely by gravity from the elevated position shown in FIG. 1 downwardly into impact engagement with the anvil 8, and pressure fluid admitted to the cylinder 4 below the piston 5 is utilized to return or raise the latter and ram 7 to the elevated position after each drop.

The elastic pressure fluid utilized to actuate the ram lift piston 5 is under the control of a main valve 10. The valve 10 comprises a cylindrical sleeve member 11 which is mounted horizontally in the head or upper housing 3 of the machine and has a valve element 12 slidable there: in. Formed in the housing 3 and surrounding the valve sleeve 11 in axially spaced relation thereto are manifolds 13 and 1.4 respectively, the former being arranged to receive pressure fluid from a fluid supply while the latter is in open communication with the lower end of the lift cylinder 4 through a passage 16.

Communication from the fluid pressure manifold 13 to the interior of the valve 12 is provided by ports 17 in the sleeve 11, while communication from the valve element to the cylinder manifold 14 is provided by other ports 18 in said sleeve. The inner end of the valve sleeve 11 is in open communication with an exhaust port 19 provided in the housing 3 and opening to the atmosphere at the rear of the drop hammer. q

Actuation of the valve element 12 is effected by means of a control lever 22 disposed for actuation by the ram 7 and suitably connected to a valve rod 23. The control lever 22, constructed as shown in the drawings, is pivotally mounted intermediate its ends upon a pin 24 secured to one of the side frames 2 of the machine. Adjustably secured to the control lever-22 are dogs 25 and 26, respectively, which are arranged to be engaged by the ram 7 in the manner and sequence hereinafter set forth.

The upper end of the lever 22 is pivotally connected to the inner end of a link 27 which has its outer end pivotally connected to an arm 28 fixed on a pin 29 mounted in the side frame 2 and having an arm 29a fixed on its other end. The arm 29a, in turn, is pivotally connected to the lower end of a vertically extending rod 30, the upper end of which is connected to one arm of a bell crank cation through the valve from the manifold 13 to the manifold '14. so that pressure fluid is admitted to the h'it" cylinder 4 causing the piston 5 and ram 7 to be actuatedv upwardly. Following this, and in normal operation of the drop hammer, upon engagement of the upper dog 26 i by the ram 7 during its upward movement, the lever 22 is actuated in the clockwise direction resulting in shifting of the valve 12 back into the position shown, thus interrupting flow of pressure fluid to the cylinder 4 and exhausting fluid previously admitted to said cylinder to the atmosphere through the exhaust port 19.

A suitable elastic fluid under pressure is supplied to the main valve 10' from a main pressure fluid supply line fluid underv pressure to the pipe 32a resulting in actuation of such clamp release mechanism 32'to allow the ram 7 .to drop;

As previously stated, the full stroke of the ram 7 is controlled by the dogs 25 and 26 on the lever 22. Short strokes are made possible by the same mechanism with the addition of the apparatus associated with dog mem ber 35; There is provided on the control lever 22 between dogs 25 and 26 thereof,-a fluid control member 36 whereby dog 35 may be projected into the path of the ram for engagement thereby to close the valve 10 and arrest upward movement of the ram 7 at a point a selected distance below the upper limit of its normal stroke so that the length of the succeeding drop stroke of the ram is materially shortened 'or reduced in length. The con! struction and arrangement of the movable dog 35 is such that when the fluid control member 36 acts upon it, the dog 35; is so disposed that its nose is projected into the path of the ram- 7 for engagement thereby during itsupward movement. 0n the other hand, when the fluid control member 36 does not act'upon it, the dog 35 automatically'moves to such a position that its nose portion is removed from thepath of the ram 7 so that 'Rickrode- For present purposes it is suflicient to note that when fluid under sufllcient pressure is admitted to ,In the illustrated embodiment of the present invention the valve 52 is mounted at the underside of the main operating treadle 34 of the machine and the valve plunger 56 projects upwardly through an opening 57 in the treadle as shown in FIG. 1 of the drawings. This arrangement aitords the operator great convenience in manual op eration of, the hammer. Simply by, changing the position of his foot on the treadle 34 he is able to establish pressure fluid flow solely to the clamp release mechanism of the machine or simultaneously to both the said release mechanism and the adjustable dog fluid control member 36 at will as may be desired.

Heretofore in a typical forging operation of the drop hammer, the operator had to learn the pattern of blows determined to be best for that particular forging. Typically, the operator might make the first vt'ew blows of V the operation with the ram operating through its full stroke simply by depressing the main toot treadle 34 of the machine and the remaining blows of the operation by a shorter stroke of the ram 7 simply by shifting'his foot on the treadle 34 so that in the act of depressing the latter he also depressed the plunger 56 to open valve 52 and thereby admit pressure fluid to the fluid control member 36 causing the dog .35 to be projected into the path of the ram 7, thus causing the ram to operate through a stroke of substantially reduced length. With simple stroke patterns, there was little diificulty in remembering and performing the strokes in correct sequence. As patterns have become longer and more complex, however, particularlyin those cases where the detrol system of the present invention will be apparent.

Such a systemlends itself to becoming part of a com: pletely automatic control of the impact device should that become desirable.

A control circuit highly simplified for the purpose of 40 clarity is shown in FIG. 2. to illustrate a preferred embodiment of the present invention. In this specific embodiment after an initial long stroke, the hammer will automatically provide a series'of short strokes of preselected number followed by a series of long strokes of 4 5 preselected number and mayiterminate in a single short cut-ofi stroke, if desired. 7 The elements shown in FIG. 2 are r'elated to the structure in FIG. 1 through atreadle switch 34:: associated with and operated by treadle 34, and pressure switch 67 associated with the pressure systern. Short stroke selector solenoid 68 in automatic operthe cylinder of the fluid control member 36 the dog 35' i is thereby ia'ctuated'to position its nose portion into the path-of upward movement of the ram 7. a

.Pressure fluid is supplied to the fluid control member 36 to urge the dog 35' against a spring effect into thepath of the ram 7 by means of a pipe system 50, including a flexible portion 50a, which is connected at one end to the cylinder portion of fluid control member 36 as indicated at 51 and has its other end connected to the outlet the pipe line 50 to the fluid control member 36. On the other hand, when the operating plunger 56 is released,

the valve 52 is closed and communication is established from the pipe line 50 to the exhaust port 53 so :that fluid in the fluid control member '36 is exhausted to the atmosphere.

ation functionally replaces actuator 56. Theclamp which engages rod 6 and holds ram 7 elevated and its clamp release solenoid 66 can be seen in FIG. 1 in dashed lines.

This particular arrangement employs a pair of step- 55 ping relays 18R and 2SR each having a plurality of fixed 0 selectively connectedinto a circuit through the movable contact to a control relay which initiates the next step of the sequence. In FIG. 2, for example, as the treadle 34 is depressed, the clamprelease solenoid 66 is energized through switch 34a, thereby releasing the clamp j and -al- 5 lowing the ram to fall under gravity. The fall of the ram and actuation of dog 25, as previously described, will position valves in the fluid system in the manner described to raise the ram by supplying fluid to cylinder 4. As pressure increases, pressure switch 67 is closed and step- 7 ping relay 1SR is-energized through the normally closed contact 1CR1 of controlrelay 1CR. Stepping relay 1SR drives movablecontact or brush 1SRO clockwise as shown from one fixed contact to the next in the predetermined sequence 1SR1, 1SR2, 1SR3, 1SR4 and 1SR5 each time pressure switch 67 is .closed. These tfixed contacts are connected to fixed contacts 71, 72, 73, 74 and 75 and movalble selector switch contact 70 is positioned at the desired contact which will allow a certain number of strokes to occur before changing the position by energizing control relay 1CR. Short stroke solenoid 68 is connected across power L and L through normally closed contacts 1CR3 of relay lCR. Therefore, as the ram is allowed to fall by energization of clamp release solenoid 66, the dog 35 will bemoved into position to stop the rise of the ram 7 in its short stroke position and this will continue until relay ICR is energized. Here since movable selector switch contact 70 is set on fixed contact 73, relay 1CR will be energized when movable relay contact 1SRO reaches fixed relay contact 1SR3.

Once relay 1CR is energized, the normally closed contacts 1CR3 in series with short stroke solenoid 68 will be opened thereby causing dog 35 to be retracted by its loading spring so that the ram 7 can rise to contact long stroke dog 26. The energization of relay lCR will also.

open normally closed contacts 1CR1 thereby deenergizing stepping relay 18R and close contacts 1CR2 thereby energizing stepping relay 28R through normally closed relay contacts 2CR1. As will be discussed hereafter in connection with FIG. 3 more elaborate circuitry is required in :a practical system in order to permit proper sequencing and full cycling.

Each time pressure switch 67 is closed stepping relay 25R drives movable contact 2SRO from one fixed contact to another, i.e., 2SR1, 2SR2, 2SR3, 2SR4 and 2SR5 until it reaches the contact which is connected by movable selector switch contact 80 through a fixed contact 81, 82, 83, 84 or 85 of the selector switch. In this case selector switch contact 80 is placed on fixed contact 84 so that when movable relay contact 2SRO reaches contact-2SR4 the circuit from line L to line L through control relay ZCR will be completed. At that time, normally closed contacts 2CR1 will be opened stopping stepping relay ZSR and normally open contacts 2CR3 will be closed so that if switch 87 has been previously manually closed, a final or cut-0E short stroke will be provided by energization of short stroke solenoid 68. In the circuit shown in FIG. 2, even if treadle 34 remains depressed after the sequence has terminated, the contacts 2CR4 will open clamping the ram in the raised position.

FIG. 3 is supplied in order to show in detail the nature of: the circuitry which is necessary to make the arrangement of FIG. 2 practical. As shown, the three-phase lines 90, 91 and 92 are connected through a power switch 93 and individual fuses 94 to the primary 95 of a transformer 96. The secondary 97 of the transformer 96 is connected through individual fuses 98 to the lines L and L The clamp release solenoid 66 may be energized by connecting it across lines L and L by closing the switch 34a to the open contact shown in FIG. 3 which is done by depressing the treadle 34. Also by closing switch 34a, the potential on line L is applied to line L In this case a D.C. power supply 102 from which D.C. power lines D and D are taken is provided and connected across AC. power lines L and L If switch 100 were in the position shown, each time the treadle is depressed the clamp release solenoid 66 would be energized and would continue to be energized as long as the treadle is depressed to permit the ram to provide continuous blows. By provision of switch 101 with these contacts in the position shown, the blows would all be long but if the position of the switch 100 were changed to close contacts to put the device on an automatic operation basis, switch 101 would also be closed to function in a way presently to be described.

If switch contacts 109]) were closed, and contacts 100a opened, and the treadle 34 were depressed, the clamp release solenoid would immediately be energized through Contact v5CR3 and would remain energized until these contacts were open. As soon as the ram reached the bottom of its stroke, pressure switch 67 would close connecting time delay relay lTR across the power lines L and L Control relay lCR and time delay relay 2TR are connected in parallel with each other and in series with contacts 1TR1 across the power lines. Relays lCR and 2TR, however, are subject to the interruption after a predetermined time as the time delay relay contacts 1TR1 open.

When relay lTR is energized it will tend to open normally closed switch 1TR1 after a delay of a predetermined time. Meantime, relays 1CR and ZTR will be energized. The energizing of HR closes normally open switch :ITRZ in series with switch 2TR2- which is arranged to be normally closed but delays closing a predetermined time after being deenergized to avoid passing current while movable relay contact '1SRO is switching.

Thus the closing of relay 2CR contacts is delayed through switch 2TR2 until switching is completed. Swith 1TR1 being initially closed upon energization of relay lTR allows control relay 1CR to actuate its switches immediately. For example, normally open switch lCRl is closed upon energization of relay lCR in series with normally closed switch 3CR2 so that stepping relay 18R will be energized by connection across D.C. linesD and D Upon being energized, stepping relay ISR sets moving contacts 1SRO, 1SRO' and 1SRO" by means of a pawl and ratchet arrangement. Then immediately upon its deenergization when delayed opening switch 1TR1 opens thereby deenergizing relay 1CR and opening its switch 1CR1 the pawl is in position to actuate the ratchet and move the movable contacts one position. The movable contacts are preferably separate arms on a single shaft to which the arms are rigidly radially afiixed. The movable contacts are preferably insulated from one another and are so arranged that, While movable contacts 1SRO and 1SRO' contact similar fixed contacts, corresponding ones of which areelectrically connected together and designated by similar primed and unprimed number designators. The fixed contacts on the unprimed level of the stepping relay are Wired to the fixed contacts of the primed level in such a way as to energize a relay connected to the primed movable contact one step ahead of a relay connected to the unprimed movable contact. Each time pressure switch 67 is closed, the movable contacts of stepping relay '1SR are advanced one fixed contact. Movable contact 1SRO' will reach contact'lSRS' and complete a circuit from line L through movable selectors switch contact 70, fixed contact 76 and normally open control relay switch 2CR2 to energize control relay 4CR which immediately closes normally open switch 4CR1 in a holding circuit through that switch and the winding of relay 4CR across lines L and L On the next step of the movement of relay lSR, the contact 1SRO will contact fixed contact 1SR6, thus completing a circuit from line L through selector 70, fixed contact 76, the contacts of relay 18R, normally open contact 2CR1 then closed due to energization of relay 2CR when switch 67 is closed as previously indicated, and control relay 3CR to line L Energization of control relay 3CR causes normally open switch contacts 3CR1 to close and operate as holding switch contacts in series with relay 3CR across lines L and L Short stroke solenoid 68 is normally energized across lines L and L through switch 101 and normally closed switch contacts 4CR2 of control relay 4CR. When control relay 4CR is energized, however, these normally closed contacts are opened, the short stroke solenoid 68 is deenergized and the pattern of short strokes is set to be terminated after the next stroke which will be short because the dog 35 cannot be withdrawn from the ram path in time to avoid the upwardly moving ram 7 on that particular stroke. This is because the, pressure switch 67 is actuated by pressure increase as the ram starts to rise and time limitations in the equipment are too short and the time constants too long to permit immediate withdrawal. However, provision of relay 4CR 7 in the primed. system or in'series with movable brush ISRtl enables its energization one stroke ahead of the last stroke to be counted so that it can anticipate the counting of the last stroke. It does so and deenergizes 7 short stroke solenoid 68 by opening contacts 4CR2. Then,

on the nextstroke of the ram with the energization of relay 3CR, the stepping relay 18R is deenergized by the opening ofthe normally closed contacts 3CR2 and the stepping relay ZSR is energized by the closing of the normally open contacts 3CR3 which energize'r'elay ZSR by connecting it through normally open contacts 1CR2 between lines D and D Relay ICR is energized to close switch contacts 1CR2 when pressure switch 67 is closed. Contacts 3CR3 remain closed. once relay 3CR is energized because of the action of holding contacts 3CR1.

Like stepping relay ISR, stepping relay ZSR has three movable contacts 2SRO, ZSRG and ZSRO" and fixed contacts 2SR1ZSR7 and 2SR12.SR7'. The primed and unprimed movable contacts have the same relative relationships to one another as do the movable primed and unprimed contacts of stepping relay 1SR. Again, a movable selector switch 80 enables a circuit connection eventually through a selected one of certain fixed contacts here shown as 81, S2, 83, 84, 85, 86 and 87. Control relay 6CR will be energized when contact ZSRO' reaches contact 2SR6' in the arrangement shown and pressure switch 67 results in the closing of nor mally'open switch 2CR3. Energization of control relay 6CR closes normally open holding switch contacts 6CR'1 to place relay 6CR inseries with it across lines L and L Meanwhile full length strokes are'continued. One stroke later, contact ZSRWill close completing the circuit from L through movable switch arm 80, fixed contact 86, fixed contact 2SR6, movable contact 2SRO, normally open switch 2CR4 which is closed by virtue of energization of relay ZCR, and relay SCR to line L Completion of the cir- V cuit through relay SCR closes the contacts of holding switch CR-1 which is in series with relay SCR across ergization of relay 7CR. V 'Ihis will cause holding switch 7CR-1 to close connecting relay 7CR across lines L and L regardless ofwhether switches 1CR3 and SCRZ are opened or remain closed. It will also open normally closed switch 7 CR2 which, it the switch 105 for'manually selecting'a final cut-ofl? blow is closed, will enable interruption and deener-gization of the clamp release solenoid after the final cut-off blow. However, if the switch 105 is open, it will prevent energization of the clamp release solenoid and cause the cycle to terminate without a final cut-ofi blow inasmuch as switch '5CR3 has opened. Relay SCR also closes switch 5CR4 through reset relay RCR which through switches RCRl and RCR2, thereby, closes the D.C. circuit through the reset brushes 1SRO" and 2SRO'. and through normally closed stepping relay contacts 1SR9 and 2SR9 to continuously energize the stepping relays 18R and 25R until they are driven back to their starting position.

It should also beobserved that if treadle 34 is released in the course of operation, its switch 34a will open the circuit through the pressure. switch and close a circuit across line L and L through the reset relayRCR. Also when the treadle switch is opened by release of the treadle, all of the circuits through the holding switches will be deenergized allowing the relays to drop out and interruptin'g the forging cycle with the ram in striking position. The forging cycle can be initiated again by the sequence previously described. The fact thatboth of the relay switches SQRS and 7CR2 are opened will insurethat the cycle will'notrepeat if the treadle is kept depressed and the treadlejswitch 34 is closed. Therefore, in order to initiate a new sequence'of blows, the treadle switch must be released, reset and reclosed.

r In many instances, it may be desirable either to vary the pattern of ram blowsequences or to have more than just two stroke lengths. The system of FIG. 4 shows clectrically how asystem with three stroke lengths might be employed. A minimum stroke length would be set up in the same way that a short strokelength is set up but by means of a separate solenoid corresponding to 68 in FIGS. 2 and 3 actuating a separate dog corresponding to dog 35 but at the appropriate intermediate level. It may also be desirable to Vary the sequence of the groups from time to time, and the system of FIG. 4 permits this to be done. a

Referring more specifically to FIG. 4, it will be observed that the circuit shown is even more schematic thanFIG. 2 and that the contacts of thestepping relay and the selector switches have been lumped into boxes which for convenience have been given the same number designator as the relay by which they are controlled; The-linesl and L the treadle switch 34a, the pressure switch 67 and the clamp release solenoid 66 correspond to those in FIG.- 2. Instead of a single short stroke solenoid 68, there is a short stroke solenoid S vanda medium stroke solenoid M provided. Use of a retractable longstroke solenoid L is also suggested although it is not necessary in a system providing three stroke lengths.

1n the circuit illustrated,'four stepping relays ISR, ZSR, 38R and 48R are employed. Theprefix number before the stepping relay indicates the sequence of actuation of these relays. The relays are arranged in parallel .circuits in series with the pressure switch'67. The control relays are so arranged that the stepping relays will cause them to be energized in the sequence of their prefix numbers. Thus ,itwill be. seen that 18R ,is first, energized through the normally closed switch contacts lCRl of control relay ICR. At the same time, other stepping relays have open switches in series with them. Relay vISR will continue to he energized untilit completes a circuit through the selector switchcontacts to complete the. circuit-through control. relay ICR which will thus open the normally closed contacts of switch vICRltand close the normally open contacts of switch. 1CR2 associated with the relay. Relay ICR will also close the normally open contacts of switcl'rlCRS. s

In similar fashion, after the stepping relay ZSR has reached its selected position, relay ZCR Will be energized thus opening normally closed contacts 2 C R1 and thereby deenergizing relay 28R and' closing normally open contacts of switch 2CR2, thereby. energizing stepping relay 35R. through the normally closed contacts of switch 3CR1. This process is continued through relay 48R which when it closes to the selected contact may, open normally closed contacts 4C R2 which, are in series with the clamp re lease solenoid 66,, thereby causing-the ram to be clamped on thelastmoye upward, The length of the strokes are, o f course obtained by h Stroke l th sel t n m a s a t e ckc'l t solenoids S, M and L. Actually, the stroke of solenoid L may o be pl y ju as no s l r s l n i m y be employed in the FIG. 2 arrangement. Selector switches desig at 7185.288. 8S, 4SS y t e r s ng connections, all have contacts which. may be, openedtand closed in series. with any one of the stroke length selector solenoids S, M .or L,.but only one solenoid is energized'by. each selector switch. The selector switches are selected in a particular sequence because of thearrangement of control From the above description, it will be seen that by this means it is possible to place strokes of any length in any desired sequence by techniques previously shown, select the number of strokes in each sequential group and by addition of more relays increase the capacity of the programmer either in the direction of permitting more groups of strokes or in the direction of permitting selection of more lengths of stroke.

It will be appreciated by those skilled in'the art that the means illustrated herein are merely by way of example and not by way of limitation. Other means of providing multiple patterns within the spirit of the teachings and the scope of the claims are intended to be within the scope and spirit of the present invention.

.We claim:

'1. A stroke programmer control system for an impact device having means permitting selection of strokes of more than one length comprising at least one means for actuating each of the stroke length selector means, counting means for counting strokes of the impact device and sequencing means responsive to the counting means and associated with at least one less than the total number of actuating means to terminate a sequence of strokes of a particular length at a selected count and initiate a sequence of blows of another predetermined length.

2. The stroke programmer of claim 1 in which there is provided separate counting means for counting the strokes of each length.

3. The stroke programmer of claim 2 in which there is provided in each counter, means for manually preselectin g the count of strokes of a particular length.

4. The stroke programmer of claim 1"in which a sequence of groups of strokes of aparticular length is predetermined and a counter is provided for each group of strokes of a particular length.

5. The stroke programmer of claim 4 in which means is provided whereby any desired sequence of groups of strokes of difierent lengths may be preselected.

6. A stroke programmer control system for an impact device having means permitting selection of strokes of more than one length comprising at least one means for electrically actuating each of the stroke length selector means, counting means associated with each of the actuating means for counting strokes occurring during actuacounting means is in circuit with the actuating means with which it is associated and is so arranged that it closes a circuit through its associated sequencing means at a pre-selected count.

8. The stroke programmer of claim 7 in which the actuating means may be freely substituted for one another in the circuits of the counting means so that the sequence of stroke groups may be varied thereby.

9. The stroke programmer of claim 7 in which the counting means is a stepping relay having a driven contact and at least one fixed contact toward which the driven contact is advanced with each stroke and at which the driven contact arrives to complete a circuit through the sequencing means at the preselected count.

10. The stroke programmer of claim 9 in which each sequencing means is a control relay which opens a normally closed switch in the circuit of the stepping relay by which relay it has been energized and closes a normally open switch in the circuit of the next succeeding timing relay.

11. The stroke programmer of claim 10 in which there is provided a holding relay which is arranged to be energized upon the closing of the switch of the stepping relay and which is arranged to hold closed the normally open fixed contacts is selectively connectable to one power line and the driven contact is connected to the other power line so that when the driven contact reaches the selected fixed contact a circuit across the power lines will be completed through the appropriate relay.

13. The stroke programmer of claim 9 in which each stepping relay is arranged to be connected in series with a switch which is closed once during a stroke cycle.

14. The stroke programmer of claim 13 in Which'the switch is a pressure switch positioned to be closed by fluid pressure in the fluid system of the ram operator of the impact device.

References Cited in the file of this patent UNITED STATES PATENTS 1,924,545 Fitzgerald et al Aug. 29, 1933 2,604,071 Rickrode July 22, 1952 2,766,711 Dever et a1. Oct. 16, 1956 2,837,059 Tomka June 3, 1958

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