US2322294A - Feeding mechanism for power presses and like machines - Google Patents

Description

June 22,1943. M. D. HEYMAN 2,322,294

FEEDING MECHANISM FOR POWER PRESSES AND LIKE MAQHINES I 159 161-- Q H6 14. 16.2

v 11.5 INVENTOR 62 119 MOSES 0. HEY/WAN OZMM, A ORNEY June 22, 1943.1 M, D. HEYMAN 2,322,294

I FEEDING MECHANISM FOR POWER PRESSES AND LIKE MACHINES Filed Jan. 8, 1941 5 Sheets-Sheet 2 I t J 5 INVENTOR M0655, 0. HEVMAN E TTORNEY June 22, 1943. M D.HEYMAN .2,322,294

FEEDING MECHANISM FOR POWER PRESSES AND LIKE MACHINES Filed Jan. 8, 1941 5 SheetS-Sheet 3 Winn p mmmmmmllllhf filllllmlllll'flfllm 74 7 V/// I f 46 jllll=-.-.-.-:::: iim Z I 4 v 4 -"|NVENTOR M0555 0. HEVM/l/V ATTORN June 22, 1943.

M. D. HEYMAN FEEDING MECHANISM FOR POWER PRESSES AND LIKE MACHINES Filed Jan. 8, 1941 '5 Sheets-Sheet 4- June 22, 1943. HEYMAN 2,322,294

- FEEDING MECHANISM FOR POWER PRESSES AND LIKE MACHINES Filed Jan. 8, 1941 5 Sheets-Sheet 5 INVENTOR M0555 0. HEY/WAN M ATT RNEY punch of such Patented June 22,

UNITED STATES PATENT orrice FEEDING FOR POWER 7 Moses D. Hey'man, Cedar-hunt, N. Y., assignor of one-half tolrene K. Heyman, Cedar-burst, N. Y.

Application January 8, 1941, Serial No. 373,571

11 Claims.

This invention relates to mechanisms for feeding punch presses and the like and deas more particularly with machines for feeding preformed work blanks to be drawn and formed in a secondary operation.

Feeding work blanks, for secondary operations,

to a power press is generally conceded to be the most hazardous type of work. For the protection of the operator, many devices have been tried in attempts to render manual feeding safe. These so-called safetydevices are designed to prevent operation of a power press when the hands of the operator are in the path of movement of the presses. One such device entails the use of handcuffs chained to arms which pull the operator's hands to safety when the press is tripped. Another employs a swinging gate in front of the die which frequently operates with such force as to bruise the hands and arms of the operator while seeking to give safety. Still another provides grips which'must be grasped before the press is tripped.

The devices heretofore known, either subjected the operator to punishing blows or so controlled the movements of his or her hands as to materially impair efllcient feeding. Presses equipped with such devices are exceedingly unpopular both with the press operators and with the factory management. Feeling that their earning capacity is being impaired, operators, particularly piece workers; will frequently nullify the safety devices and thus seek greater production despite the risk 7 involved.

The invention, therefore, .has for its primary object the provision of a machine for feeding work pieces to a power press or the like in a rapid, efficient manner and with absolute safety to the operator.

Anotherobject of the invention is to provide feeding mechanism which is capable of a great range of adjustment in order to adapt such mechanism to present presses and dies.

Another object resides in the provision of means whereby the mechanism may be quickly set up' for guiding the manual placing of work pieces in such relation as to be properly fed to .the press.

A further object is to provide means for transferring a work piece to the press from'a point remote therefrom and to incorporate mechanism which will render the press inoperative if the transfer and the depositing of the work piece on the die of the press, is faulty.

The invention has for a further object the provision of a guard in front of the press and so arranged as to prevent the operator reaching the pro with said guard in position, removal of said guard entailing inoperativeness of the press. The invention also contemplates a novel form of work piece transfer means for moving the work from an index table to the press.

A still further object is to provide novel means for mounting the feeding mechanism on a power press and to incorporate adjustment features for obtaining exact alignment and positioning of the index table thereof with respect to the die of said press. 7

Briefly, the invention contemplates feeding mechanism whereby an operator may deposit work blanks at a point remote from the die of a power press; in which a guard is interposed between the operator and the press and which, when removed,'will render the press inoperative; which will transfer a work piece from the point of deposit to the press die; whichwill render the press inoperative, should the transfer be faulty; which' is provided with means which becomes uncoupled from the press tripping mechanism upon such faulty transfer and must be manually recoupled of the invention and others which will later become evident, are realized in a mechanism and combination such as illustrated in the accompanying drawings showing an embodiment, which, while preferred, may be changed in arrangement and proportion within the scope of Hence, the drawings, together cation, should be considered as by way of example only. a

In the drawings: Fig. 1 is a top plan view of a feeding mechanism combined with a power press and incorporating features of the invention, the power ress being shown in dot-dash lines and partly broken away.

Fig. 2 is a side elevational view thereof.

Fig. 3 is an enlarged fragmentary detail plan view partlyin cross section, of the index table and related parts, and illustrating one form of work piece guide means.

Fig. 4 is a vertical sectional view as taken in the plane of the line 4-4. of Fig. 3.

Fig. 5 is a fragmentary plan view of the index table, showing another form of work piece guiding and positioning means.

' faced to insure parallelism of said brackets.

Fig. 6 is a. top plan view of a preferred form of transfer arm. I

Fig. 7 is a side elevational view thereof.

Fig. 8 is an enlarged plan view of the work piece grasping portion of the transfer arm in grasping condition.

Fig. 9 is a broken vertical sectional view of the transfer arm support post in raised condition.

Fig. 10 is an enlarged broken side view of the means for dis-connecting the feeding mechanism from the press tripping means and shown in uncoupled condition.

Fig. 11 is a. similar view of a pneumatic or vacuum control valve employed in the mechanism.

Figs. 12 and 13 are fragmentary detail sectional views showing the support arrangement of the guard or shield.

Fig. 14 is a wiring diagram of a control circuit employed in the machine.

Fig. 15 is a fragmentary plan view of an alternate form of means for adjusting the index table.

ram (not shown) for operating on pieces of work fed to said die. In the usual manner, the press i provided with support legs 23 and with one revolution clutch mechanism (not shown) whereby the punch is operated when said mechanism is tripped.

The feeding mechanism contemplated herein is preferably entirely mounted upon and supported by the press to provide a combined structure supported by the press legs 23. To this end, a pair of brackets 24 are secured to, the press as by bolts 25 which are threadedly engaged in the sides of the bed 2|, said sides being spot In this manner, said brackets become, in effect, an integral part of the press. The brackets 24, are each preferably formed with an inreaching suport pad 26.

While thus firmly secured, it i preferred. to further insure against inadvertent derangement of the brackets 24 by providing means such as the braces 21. eachvbolted at 23 to one end of its respective bracket, and similarly bolted, at 29 to the press legs 23. Each brace 21 is preferably adjustable in length as by means of the tum-buckle arrangement 30 which may be utilized for leveling the brackets with respect to each other.

A support base 3| for the feeding mechanism is supported on the brackets 24 and means are provided for accurate positioning and leveling of 22. When properly positioned, the bolts 34 are employed for locking the base 3| to the arms 24.

In the above manner, the feeding mechanism upport base is securely mounted upon the press and cannot ordinarily become misaligned. It, in effect, becomes part of the press and subject to all, if any, of its movements. With this arrangement, the accuracy of the feed cannot be im paired by small relative vibrational movements between the press and the feeding mechanism, a, condition which might exist were the feeding mechanism separately supported.

As contemplated, the mechanism is provided with an index table generally designated 35. This table is remotely positioned from the die 22 and,

is provided with a plurality of work piece receiving stations 36 upon which the operator deposits work pieces to be transferred to said die.

The index table comprises a plate 31 upon which is mounted a ring 38 which is removably secured as by screws 33. The index table is arranged to rotate intermittently to bring the stations 36 successively nearer to the die 22 where a transfer arm picks up a work piece from such a near station and transports it to the die. It is contemplated to use either a suction arm for this purpose or a grasping arm such as illustrated. The former type of arm may be one such as illustrated in my Patent No. 2,130,235, granted September 13, 1938.

When a suction arm is used, it is preferred that each station 36 be in the form of a raised member 40 (shown in Fig. 3) which serves to nest the work pieces and thus guides the operator in manually depositing said pieces upon the index table. From its nested position, a suction arm may readily pick up a work piece for transfer to the die.

When a grasping arm is used, it is preferred to form each station 36 as a seat 4| formed in j grasping arm and-that the seat 4| may be used with a suction arm. In fact, the controlling factor -in the choice of arms is whether the work piece is imperforate and has a flat surface for the application of suction.

ranged to impinge against the upper surface of the other bracket pad 26. The left side of Fig. 1 hows the former arrangement and the right side of Fig. 1 and Figs. 3 and 4 show the latter ar- The use of a ring such as 33 lends flexibility to the set-up, it only being necessary to design a ring having work piece stations according with the shape of the work piece and to aflix said ring to the-plate 31 by means of the screws 39'.

It becomes necessary, from the above, to provide for regulating the elevational position of the index table with respect to the base support which need not be disturbed when aligning the index table and the die. One manner of accomplishing this in a rapid and expeditious manner is to provide a shouldered quill 42 which is locked to the base 3| as by means of a nut 43 and in which is threadedly engaged an elevating screw 44 provided with a hand wheel 45. The end of the screw 44 is engaged by astub shaft 46 which is bolted to the plate 31 and which is guided in a bore coaxial with the threaded seat for the screw 44 in the quill 42. Rotation of the hand wheel 45 in one direction will elevate the index table with respect to the base 3| and rotation in the other direction will lower it.

table 35.

After being properly. set, the index table may be locked to one or more studs 41, carried by the progressively rotating member 48 which rotates upon the quill 42 and is held against vertical movement as by means of a. spanner ope-rated nut 49 threadedly engaged with'said quill.

means of the .top nuts 58 and the bottom knurled nuts In this manner the index table 35 is adjustably flxedwith the member 48 with which it intermittently rotates upon the quill 42.

' Figs. and 16 illustrate a modification wherein the table top isleft clean and unobstructed. Instead of the stub shaft 48, an intermediate spider member 52 is'provided, said member being formed with a shaft stub 53 disposed in the quill 43. This shaft stub is engaged by the screw 44 in the samemanner as was the stub shaft 46. The

. studs 41 mounted in the rotating member 48 and extend onthrough bearings 54 of the intermediate member 52, which, when the screws 55 are loosened can be elevated or lowered by the hand wheel 45"and the screw 44. When the screws 55 are locked, the member 52 is locked to the rotating member 48.

Each stud 41 is arranged to pass through an opening in the plate 31 and to be locked thereto as by of the sleeve 8|.

nected as to a pin 98 on arm 82 and to a fixed bracket 9| on one bearing 88, serves to urge the The index table 35 is secured to the member 52 as by a bolt 56 and means such as the .screw 51 and the slot 58 in the table plate 31, may be provided for rotational. adjustment of .the table to bring its stations 36 into proper position with respect to transfer means to be later described.

, ing said-slide in the other direction; The slide 64, therefore, moves in a reciprocating manner,

and is guided in slideways 68 formed in the base 8|.

Through the medium of a link 69, the reciprocation of the slide 64 impartsan oscillatory motion to a ring 18 surrounding the member 48 and held thereon by a ratchet wheel 1| which is se-' cured to said member 48, said ring being freely confined between said ratchet wheel and a shoulder 12, formed on the member 48.

The ring 18 may be provided with an extension I 13 upon which is mounted a pawl 14 aligned with the ratchet wheel to engage the teeth thereof. The oscillatory motion of the ring 18 thus imparts intermittent rotary movement tothe ratchet wheel 1|, to the member 48, and 'to the index It'is preferred ,to restrain the intermittent movement of the index table and toinsure immovability during-its periods of rest. For this purpose it is preferred to employ a drag in the form of a brake band; 1.5 which operates in .a

groove formed in the enlarged portion 16 on'the member 48. An abutment 11 is provided for one end of the brake band and the other. istensionally held as by means of a-compression spring 18, the tension of which may be varied by a nut 19. By such means, the index table is prevented from over-running its feed as imparted by the pawl 14 and is held immobile during its rest periods.

From the foregoing it may be seen that an operator stationed at the frontof the machine (at iii a cam I88 on the camshaft 62.

the left of Fig. 2) may deposit work pieces upon the stations 88 nearest to him in an accurate,

rapid and safe manner and at some considerable distance from the die 22. The intermittent. v

movement of the index table will then transport said work pieces in a direction toward the die from which point said work pieces will be successively transferred to th'e'die in a manner now to be described.

Reference is now made to Figsl and 2 and particularly toFigs. 6 to 9 inclusive, whichillustrate a preferred form of transfer arm for transferring the work pieces from the stations 36 to the die 22.

Upon the base 3| there is preferably secured a quill 88 which serves as a support post for an oscillatingsleeve 8| provided with an arm 82. This arm,

through a link 83'and adjustment means 84, is connected'to a slide bar 85 guided for reciprocating movement in guide bearings 88. A cam follower 81 on the slide bar '85'is engaged with a cam 88 on the cam shaft 62 to urge the slide bar in one direction and thus cause partial rotation Means such as a spring 89, conslide bar in th other direction to cause reverse partial rotation of the sleeve 8|. It will be noted that the sleeve 8| is positively-rotated in a direction to move the transfer arm away from the die so that if failure of the spring 89 should occur,

' the arm would surely be out of the path of movement of the press punch.

The quill 88 also serves to support a vertically reciprocating sleeve 92 which is keyed as at 93 to the sleeve 8| and thus oscillates therewith. The vertical reciprocating motion is imparted to the sleeve 92 through the medium of a rod 94 which is carried by the cap 95 of said sleeve'and extends down through the quill 88 to a point below the base 3|. This protruding rod end is arranged to beiengaged by an adjustable pad 96 carried by one end of a lever 81 fulcrumed as at 98 to'the' base 3|. The other end of said lever is provided with a cam follower 99 having engagement with In this manner, vertical movement, in one direction, is imparted to the sleeve 92. The reverse vertical movement is effected by a spring I8| disposed within the sleeve 92 and around' the quill 88, said spring being confinedbetween'a head I82 on said quill and a shoulder I83 on said sleeve 92.

The transfer arm generally designated I84 is mounted upon the-sleeve 92 and is thus arranged for both vertical reciprocating movement and for horizontal oscillating movement. To suit all types of work, the transfer arm is preferably adjustably secured to the sleeve 92 and for this purpose said sleeve is provided with ear brackets I85 which are jjpreferably slotted as at I86 for stud bolts' 'l81 carried by complementary ear brackets|88 formed on a member I89 comprising the relatively fixed portion of the transfer arm As herein contemplated, the arm member I89 is [preferably formed with bearing 'brackets II8 uponwhich ismountedas by means of the pin III, a relatively' movable'arm'member I I2. The two arm members I89 and 2 are maintained in definite relative position under normal circumstances by means such as a springl I3 and an adjustable stop screw 'I |4. should something abnormal, however, engage the arm member 2 during its transfer motion, it will tilt on its pivot pin against thetension of the spring II3.

' Thisabnormal tilting of the arm, in the present instance, is utilized for breaking an electric circuit controlling the press tripping mechanism which will be later described. For this purpose, a limit switch H is mounted on the relatively fixed arm member I09 and is provided with a switch button I I6 in the path of movement of an adjustable screw I" carried by the relatively movable arm member II2. A screw H6 is provided to limit the tilt of said member II2 to obviate damage to the switch II5.

It is obvious from the above that during all normal conditions of operation, thetransfer arm will be held by the spring H3 and the stop screw I I4 in proper position to effect the transfer of work pieces from the index table 35 to the die 22.

Should, however, one of the work pieces not be properly positioned at a station 36, or should the die not be cleared of the previously formed piece,

the arm member will be' tilted by any such obstruction to cause the screw II! to push the button I I6 and open the switch I I5, which' opens the mentioned controlling circuit. A manual reset button H9 is provided on the switch II5 for reasons later apparent.

The transfer arm I04 may be provided with a I suction head such as disclosed in my mentioned patent and, except for the safety features herein disclosed, may follow that design and be employed for certain types of work. The present disclosure shows a work piece grasping type of arm as detailed in Figs. 6, 7, and 8. A particularly valuable advantage of thedisclosed type of arm is that two or more pieces may be picked up thereby for sub-assembly in the die 22, a safe operation in the present mechanism but extremely hazardous heretofore.

The armmember I04 is preferably fitted with an extension I20, adjustably mounted as by means of .a slot and bolt connection I2I, and,

depending on its relation with the transfer station and the die, formed wtih an oil-set portion I22. The latter portion is preferably provided movement imparted to them at their connecting pivot I21 will cause a lesser but powerful movement of the slides I24 towards each other.

This movement of the slides is imparted through a rod. I29, connected to a bellcrank lever I30, pivoted to the extension I at I3I, and connected by a link I32 to a piston I33 operating in a cylinder I34. A vacuum or suction connection is made to the cylinder at I35. A spring I36 within the cylinder serves to hold the piston in outermost condition when the'suction is not applied and in this condition holds the slides I24 and the grasping members I apart until suction is applied to the cylinder I34. This condition is shown in Fig. 6. When suction is applied to the cylinder, the piston I33 will be drawn inwardly to operate the system of links and levers to break the toggle and to draw the slides towards each other as shown in Fig. 8, A pin I31 is provided to project into the area which would be occupied by a work piece that might'be in the path of vertical movement of the arm I04.

The grasping arm extension I20 has been so designed as to render it applicable for the transfer of a great number of differently shaped work pieces, it only being necessary to change the grasping members I25 which are designed for each size and shape of work piece or work pieces a to be acted on.

A vacuum control valve I- may be used for applying suction at the proper time to the cylinder I34. Such a valve is shown in Figs. 2 and 11 and is detailed more fully in my mentioned patent. A cam I30 on the cam shaft 62 is designed and arranged to operate the stem I40 01' said valve to admit atmospheric pressure to the cylinder I34 when desired and to apply suction from a suction line I to said cylinder when grasping of a workpiece is desired. When a suction transfer arm is used, this same vacuum control valve may be employed in connection therewith in the manner set forth in my earlier patent.

corporates a master on andoff switch I44, the

vacuum pump I43, the previously mentioned limit switch H5, and a solenoid I45. As previously stated, when the arm I04 is tilted by interfering matter, the button II6 of switch II 5 is pushed to open said switch and the control circuit. The circuit and switch remain open until the button I I9 is pushed manually. In the present machine, the opening of the circuit, which causes de energization of the solenoid I45, serves to stop the operation of the press tripping mechanism.

Reference is now made to Figs. 2 and 10 wherein the press trip rod I46, whichoperates the onerevolution clutch means of the press or similar means, is connected to a bell crank lever I41 pivotally mounted on the press frame. This lever is provided with a pin I40 which, during normal operation of the feed, is engaged by a yoke I43 mounted on a bar or rod I50. Means are provided to oscillate said bar or rod and preferablycomprises a cam I5I' on the cam shaft 62 and a bell crank lever I52, pivoted to the frame 3| at I53, and connected with said bar or rod I50. The

bell crank is provided with a cam follower I54 for engagement with the cam I5.I. It is evident that each revolution of the cam ,I5 I will cause the trip rod I46 to trip the press once so long as the yoke I49 is engaged with the pin I40.

Under normal conditions of feed the solenoid I45 is energized, as explained, and will attract the armature I55. The latter is provided with sling or cradle I56 for the rod I50 to support the same for coupling engagement between the yoke I40 and pin I48. So long as this condition is maintained the press will trip with each revolution of the cam shaft and with each oscillation of the transfer arm I04 and synchronously therewith.

When the feed is abnormal, the switchv II5 will be opened to cause de-energization of the solenoid I45. The armature I 55 will then drop, removing the support for the rod I50, and disengaging the yoke I49 from the 'pin I48. Continued rotation of the cam shaft willmerelv reciprocate the rod I50 without operating'the press tripping mechanism. The operator may then, in safety, correct the condition which caused the switch II5 to be opened and re-start operation by manually moving. the armature into the field of the solenoid (thus simultaneously recoupling the yoke andpress tripping mechanism) and pressing button II9 to close switch H5.

The solenoid is preferably placed at a point of the machine which'cannot be reached fromthe operators position at the front of the index a table. It is, therefore, necessary for him torelease the foot switch which is provided for closing operator without impairing efiiciency and that it is entirely unnecessary to give ready access to the die 22. Hence a guard or shield may be so mounted as to be interposed between the die and the operator when the latter is in work piece de-v positing position. Such a guard is shown at I51 and may be transparent so as not to impair visibility of the transfer means of the machine.

So as to nullify any tendency on the part of.

the operator to remove the guard, one of its support posts I58 is arranged to rest upon and maintain closed a-limit switch I59 preferably secured to the base 3| and disposed beneath'one of the sockets I60 for said posts. This switch may be incorporated either in the motor circuit ,or, as shown, in the control circuit of Fig. 14. Thus, the machine will operate only with'the I guard in position as a further safety device.

The described control circuit may be combined with the electric circuit which operates the feed mechanism. Referring again to Fig. 14, three-- phase line current is brought to the line switch IIiI and then carried to the motor 60 which drives the cam shaft 62 through the speed reduction unit 6|. The current to the motor may be controlled by a foot operated switch as described,

said switch being shown at I62. The mentioned control circuit is connected to the line current, as shown. As previously stated, the switch I59 which is held closed by the guard I51 may be placed in series in the line I63 from the line switch to the foot switch I62 so that, when said switch I59 is opened the motor circuit is opened. The circuit, as shown, would be for'three-phase current for the motor- 60. However, where the size of said motor permits, single phase current could be employed with attending simplification of the circuit.

In the above manner, a completely safe and highly efficient feeding mechanism for power presses or like machines has been provided. The

speedat which an operator can feed work pieces to the stations on the index table will control the speed at which the motor 60 can be set to drive the transfer mechanism and the press tripping operating means. It will be noted that the feed means is under the control of the operator and that the feed controls the operation of the press which thus cannot operate unless the feed is proper. It will also be seen, that the operator's movements, while controlled, are entirely normal and that he is not subjected to punishing blows" should he attempt, due to inexperience, any improper actions.

While this disclosure deals with a combination including a power press, it is obvious that sec-. ondaryoperations and sub-assembly work may be carried out in a spot welding machine to which manner. The term .like machines" is, therefore,

intended to inclucle spot welders and other ma- I chines in which secondary operations may be. performed.

Having thus described my invention, what I claim as new and desire to secure-by Letters Patent is:

- l. The combination with-a die and tripping I mechanism for the punch of said die, of feeding mechanism for said die comprising a work piece 7 receiving support me'an s for transferring work v pieces from said support to said die, said trans.-

ferring means comprising an oscillating arm having a tiltable portion, said tiltable portion being adapted to tilt upon encountering interfering matter during its work piece transferring movement, means for operatingsaid tripping mechanism synchronouslywith the movement of said transferring means, an electric circuit including a solenoid for maintaining said last mentioned means operative during normal operation of said transferring means, and a switch in said circuit adapted to be opened by said-tiltable portion for de-energizing the solenoid .and thereby rendering said tripping mechanism inoperative.

2. In afeeding mechanism for power presses and the like, a transfer member, means for oscil- Y lating said member, means .for reciprocating said member at the end points of oscillation, a switch on said member for controlling an electric'circuit, anda portion on saidmember adapted for relative movement to operate said switch upon. en-

countering interference during the' reciprocating movement of said member. I

3'. In a feeding mechanism for power presses and the like, a transfer member comprising a sleeve having both oscillating and reciprocating movement, an arm pivotally carried -by said sleeve, means for maintaining said arm in a desired normal position with respect to said sleeve, a switch carried by said-member for controlling an electric circuit and normally closed during the normal f position of said arm, and means on" said arm for I engagingthe Switch to open said circuitupon said arm being tilted on its pivot by interferingmatv ter in the path of reciprocation of said member.

, 4.111 a transfer arm having an oscillating and I reciprocating portion, a tiltable portion carried thereby, and means for maintaining said tiltable portion in normal aligned relation to said oscillating and reciprocating portion during normal movements of-said arm, said tiltable portion being adapted to yield and to tilt upon encountering. interfering matter during the reciprocating H movement of said arm.

5. The combination with tripping mechanism 7 for the punch of a power press-or .the like, of a. member for actuating said tripping mechanism,v a yoke, separably engaged with" said actuating member; means to-reciprocate said yoke to cause said actuating member to operate said tripping. mechanism, and an energized solenoidfor holding said yoke engaged with the actuating 'mem-.

ber during normal operation of the press, abnor- -,mal operationof the presscausing de-energization of the solenoid, and release thereby of the engagement between the yoke-and the actuating member to render the tripping mechanism inoperative. v

6. In combination, a power press having a die, a work piece receiving support, means for moving said' support to transport work pieces from a point remote from the die to a nearer point, a-

guard mounted between said remote point and the work pieces are fed in the herein disclosed said die and nearer point, and an operating circuit for said work piece moving means and including a switch maintained closed by said guard.

7. In combination, a power press having a die, means for feeding work pieces to said die including a support, work piece receiving stations on said support, means for intermittently rotating said support to transport a work piece from a point remote from the die to a nearer point, an

operating circuit for feeding means, a normally open switch in said circuit, and a guard positioned between said remote point and said die and nearer point, said guard having a member engaged with said switch for holding said normally open switch closed. v a

8. In combination, a power press or the like including mechanism for tripping the same, means for feeding said press, a control circuit for said feeding meansincluding a foot actuated switch, means coupled with said tripping mechanism for operating said tripping mechanism synchronously with said feeding means, a control circuit for said lattermeans, and a switch in I said last mentioned control circuit for opening the same upon an abnormal condition in the feeding means touncouple the press tripping operating means from'the press tripping mechanism to renderthe press inoperative during continued operation of the feed means.

.9; In combination, a power press or the like including mechanismfor tripping the same, means coupled with said tripping mechanism for operating the same, means for feeding the press t synchronously with the operation of the tripping mechanism, operating means, common drive means for the tripping mechanism operating means and the press feeding means, a control circuit for said drive means including a normally open switch maintained closed by the operator of the machine, a control circuit for the tripping mechanism operating means, and a normally closed switch in said latter circuit adapted to be opened upon an abnormal condition in the feeding means to uncouple. the press tripping operating means from the press tripping mechanism to render the press inoperative during continued operation of the feed means.

10. A machine of the character described comprising feeding mechanism, drive means for said mechanism, a control circuit for said drive means including a switch maintained closed by the machine attendant, means driven by said drive means for operating said machine synchronously with the feeding mechanism, and a control circuit for rendering said last mentioned means inoperative upon abnormalinterference with the feeding mechanism during continued operative movement of said feeding mechanism.

11. In a machine of the character described, in combination, work piece feeding mechanism, means for operating on said work pieces, a guard interposed between said means and the machine fattendant, an electric circuit for controlling the feeding mechanism; a switchin' said circuit maintained closed by said guard, a second switch in said circuit under the continuous control of said attendant, and another electric circuit including a switch adapted to be opened upon an abnormal condition in the feeding mechanism for renderingthe work piece operating means inoper-

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