US2696251A

US2696251A - Press

Info

Publication number: US2696251A
Authority: US
Inventors: Hawkes Sidney
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-06-04
Filing date: 1952-05-31
Publication date: 1954-12-07
Anticipated expiration: 1971-12-07

Description

Dec. 7, 1954 s. HAWKES 2,696,251

Filed Bay 31, 1952 e Sheets-Sheet 1 Fig.1. 66

//V VENTOI? Dec. 7, 1954 s. HAWKES 2,696,251

PRESS Filed May :1,- 1952 e Sheets-Sheet 2 fimydwhs Dec. 7, 1954 Filed May 31, 1952 S. HAWKES PRESS Dec. 7, 1954 I s, HAWKES 2,696,251

PRESS Filed May 31, 1952 6 Sheets-Sheet 6 Fig.7.

Fig.8. 7

I, l I

United States Patent PRESS Sidney Hawkes, Biddenham, England Application May 31, 1952, Serial No. 291,174

Claims priority, application Great-Britain-June 4, 1951 14. Claims. oi. 164-43) The. present invention relates topresses of the various kinds used, for instance in the boot and shoe industry, for cutting, moulding, and compressing materials such'as leather, rubber, composition board, cork and so on.

One object of thisinvention is to provide an efiicient machine construction which gives .speedy'and effective operation without the use of heavy moving parts. An-

other and important object is to incorporate in such ma-- chines a safety device which is power'operated, so as to be positive in action andreduce the fatigue factor involved for the operator.

Broadly stated, then, the press ofthis invention comprises a frame, a buffer or platen movable relatively to said frame to perform a pressing action against a fixed bed or other counter surface of the press, means for transmitting a drive to said buffer or platen to produce a closing movement thereof in two stages, and controlmeans operable at will to initiate each of said stages in the closing movement individually.

The invention further includes a press which comprises a-buifer or platen (hereinafter called simply a buffer) for action on work on a fixed bed or anvil of the press, means for operating the press-closing movement of the buffer in two distinct stages, viz. an approach stroke by which the buffer is brought from its rest position to the vicinity of its effective position, and a power stroke in' which the buffer carries out the required action on the work, and a safety device for-operation to:provide' for restoration ofsaid buffer to its starting position after said approach stroke and without the performance of the power stroke.

Conveniently the press comprises a longitudinal frame, a fixed head, a movable buffer received within said head and extending longitudinally of said frame, a fixed bed (for supporting the work) disposed longitudinally beneath the buffer, a rotatable main shaft for imparting.

the two-stage downstroke to the buffer, and separately operable clutches for controlling the shaft drive to the buffer for each of these stages. Hence, the operator will determine by operation of the appropriate clutch, when the approach or the power stroke is to commence. If for some reason it is necessary that the power stroke shall not follow the approach stroke, then the safety device enables him to return the buffer to its top neutral position and re-start.

The clutches are advantageously coupled-in through a double-acting mechanism controlled by the operator, conveniently from a foot pedal or treadle so that one depression of'the treadle brings in the approach clutch whilst a second depression actuates the power clutch. In addition to this the operator has under his command an emergency safety device which can be operated to release the aproach clutch before the power stroke is commenced.

The approach clutch is conveniently of the dog type with two clutch elementsrespectively rigid and'loose on an auxiliary shaft driven from thernain shaft, and is advantageously such thatthe loose element can be brought into driving engagement with the fast element, by the actuation of a first abutment element. from the treadle to allow the projection of a rectractible bolt on this loose element, thereby to impartthe approach stroke to the buffer through a mechanical transmission. This first abutment element can be held in its inoperative position by a-stop which'is subsequently movable into and out of the-'way-position either (a) when the power clutch has been operatedto perform the-powerstroke of the buffer or (b) under the overriding control exertedby the safety device on operation of the latter.

This approach clutch also advantageously includes av second abutment element movable with the first such element and effective to retract the bolt and disengage the.

drive through this clutch at an appropriate stage.

The power clutch may. also be of the dog type and again have two clutch elements, the loose one of which is commanded by an abutment element operable by a de:

pression of the treadle following the first depression'and.

not overridden by the emergency control. This second clutch may carry cam means operable to shift one or more distance pieces into the path of eccentrics or.

equivalent, driven continuously from the main shaft, thereby to transmit the power stroke to the buffer. This second clutch may be disposed on the same or a second auxiliary shaft driven from the main shaft.

In the interests of compactness and ready accessibility to, or replacement of,ythe clutches, these are preferably combined into a single unit, in which case they willadvantageously share. the same fixed clutch element keyed. on a common auxiliary shaft, and .have common actu ating means which is automatically shiftable into position from one clutch to the other to enable the treadle movement to be transmitted to the appropriate clutch.

Other features of the invention will be set forth in the.

claims hereto.

A press according to the present invention, intended primarily for use in the'cutting of leather and similar materials, e. g. inthe manufacture of boots and shoes, is illustrated by way of examplein the accompanying drawings, in which:

Figure 1 is a. front elevational view of one-half ofa.

power press constructed in accordance with'this invention; Figure la is a view similar to Figure 1 of. the. other half of the press.

Figure 2 is a cross section through-the same .on the line' IIII in Figure 1a.

Figure 3 is atop plan view of th'e'clutch box carried by the press, with one half .of. the top cover of this box.

broken away.

Figure 4 is an internal view of the clutch box from the;

Figure 7 is a top plan'view of the clutch box with the left hand half of the top cover broken away to show the elements of the'power clutch;

Figure 8 is an inside end view of the elements of the gower clutch, i. e. as seen from the left hand end of the Figure 9 is an illustration of part of the locking mechanism of the approach clutch, shown separately, partly in section on line IXIX of Figure 4.

The press comprises a base frame 1' to which are secured a pair of

end uprights

2 and 3 respectively, having an anvil or bed 4 extending between them and braced by a lower cross bar 131. This bed is normally disposed in a fixed horizontal position, but can be raised or lowered, for the purposes of adjustment of the heightthereof, by means of hand wheels 5 which are secured outer ends. secured to the stem of a screw 9 rotatable in a tapped bush It? in a bracket Ill-secured to the corresponding side frame member, and the upper ends of thestemsof screws 9 are engaged in the underside of the bed 4 whose outer ends are'guided in an opening 13 in the corresponding frame.

The skins to be out are mounted in position on a hardwood block (not shown) onthe bed 4 in the usualway with a press knife surmounting them and ready to be pressed down through the work by the descending'buffer. The front of the machine, at which the operative stands, is at the left hand side of Figure 2, and it will be noted that he'has a longitudinal bracket ldimmediately before him for disposal of press-knives or other articles. At

Patented Dec. 7, 1954.

the rear, and mounted on a webbed support secured to the end frame by bosses 104, is a work table 14 for receiving the rear ends of skins during a cutting operation.

Secured between the upper ends of the end frames 2 and 3 is a fixed cross head 17 which, it will be observed, is of channel form with strengthening webs 18 disposed at intervals therealong.

The movable buffer of the press is designated 19, this comprising a transverse beam, likewise of channel form, which is guided in the openings 13 in the end frames and, as will hereinafter be explained, is adapted to carry out its downward working stroke in two stages, viz. a relatively rapid approach stroke to close the daylight of the press and bring its lower surface into the vicinity of the press knife, followed by a power stroke in which it acts on this press knife at a slower rate, but with increased pressure, to perform the cutting operation into and through the work.

The downward movement of the buffer 19 is performed against the action of return spring means located in each opening 13. Hence it will be seen that the buffer 19 has, at each end and at its underside, a stud 2t) engaged by a compression spring 21 housed in a sleeve 22 which is flanged at its upper end to form a bearing for a further and external compression spring 23 received in a socket 24 secured by screw means 25 in the end frame concerned' Mounted by flange means 26 in the head 17 is a clutch box 27 which contains two clutches respectively controlling each of the two phases of the down stroke of the buffer. This clutch box has, passing therethrough, and journalled in the ends thereof an auxiliary shaft 28 coupled at 38 with a shaft extension 39 outside the clutch box 27 and mounted in a bearing 29 in the head 17. Shaft extension 39 is provided at its outer end with a sprocket 3G driven by a chain 31 from a further and like sprocket 32 at the end of a main drive shaft 33, the main and

auxiliary shafts

33 and 28 therefore rotating at the same speed.

This main shaft 33 extends across the width of the press and is mounted in the latter, at its ends, in

bearings races

34, 34 and 35. The drive for the main shaft, which may be rotated at a speed of, say, 200 revolutions per minute, is obtained from an electric motor (not shown) through a belt to a pulley 36 at the right hand end of the shaft, which pulley also serves as a fly wheel.

The clutch mechanism in housing 27 comprises, in the first place, a central element 37 which is common to both the approach and the power clutches and is keyed on shaft 28 as at 105 (Figure 6), so as to rotate continuously therewith under the drive from the main shaft 33. This continuously rotating clutch element 37 has, at one side, an outstanding dog 40 and a similar dog 41 at the opposite side thereof.

The individual clutches for controlling the approach and the power phases of the down stroke of the buffer are respectively housed in the box 27 on the right hand and on the left hand side of the common clutch member 37, as related to Figure 1 of the drawings. Each of these clutches includes an element which is loose on the shaft 28 but is operable by means of an appropriately shaped abutment element to drivingly engage this ele ment with fast element 37 thereby to cause the clutch to perform its appropriate function.

Hence, in the case of the approach clutch (see Figures 3 to 6) the loose element is designated 42and this has therein a transverse channel 43 in which is slidably housed a bolt 44 having a head 45 projecting from the circumference of the element 42, being so held against the action of a spring 46 by means of an abutment element 47. This latter is of somewhat crescent shape in front view and is carried by a boss 48 pivoted at 49 in the box. The boss 48 also carries a second crescentshaped abutment arm 50 on the opposite side from abutment 47 and rigid with the latter.

Formed integrally with, or secured to, abutment element 47 is a forwardly projecting spigot 51 housing a plunger 52 which is urged outwards by a spring 53 so that the nose of the plunger bears at all times against the front wall 54 of the clutch box 27. In addition, the spigot 51 is formed with a lateral nose 55 co-operating with plunger 56 in a sleeve 57 having an ear 139 slidable on a cross shaft 58 extending between the endwalls of the clutch box 27 at the upper part of the latter. As will be observed, the plunger 56 is urged in the rearward direction of the box 27 in its sleeve 57 by a spring 59 bearing on a nut 60 secured to the outer end of this plunger.

Co-operating with the nut 60 is a lever arm 61 secured to a stem 62 which is rotatably mounted in the cover 63 of clutch box 27, and has secured to its upper end a collar 64 having a radial arm 65 which in turn is connected by a lever and

link system

66, 67 and 68 to a link 69 which extends downwards at the left hand end of the machine to be articulated to a lever 133, at the left hand end of the machine, which is secured to a cross bar 70 extending between

frames

2 and 3 and pivoted in these latter. A second lever 134 is secured to bar 70 at the opposite end of the machine, and both

levers

133 and 134 are connected by a treadle 71. The upper end of the link 69 is cranked and is guided by a fixed bracket 132 (see Figure 2).

As will therefore be apparent, when the treadle is depressed the link 69 is drawn downwards, thereby imparting a pivotal movement to the lever arm 65 and thus to arm 61. Such movement serves to move plunger 56 against the action of its spring 59 to contact the nose 55, and thereby swing abutment 47 anti-clockwise (as referred to Figure 4) about its pivot 49 against the action of the spring plunger 52. Such movement of abutment 47 causes the head 45 of bolt 44 to ride over an oblique or cam surface 72 of this abutment to enable the bolt 44 to be moved forward by its spring 46 into the path of the rotating dog 40. Hence, when this dog abuts the bolt 44, the clutch element 42 will turn with the shaft 28.

The drive thus made is used to effect the approach stroke of the buffer 19, inasmuch as the element 42 has secured thereto a cam 73 which in turn carries an eccentric boss 74, all rotatably mounted on shaft 28. A roller 75 runs over the eccentric peripheral edge of boss 74, this roller being carried by an arm 76 of a sleeve 77 which is pivoted on a. pin 146 journalled in a boss and in the right hand end wall of box 27. The pin 146 has connected, to the part thereof projecting out of the box, the end collar 78 of a lever, arm 79 of which extends downwards from the rear part of the box 27.

The arm 79 is articulated through a link 80 to a lever 81, which is secured on a rotatable cross shaft 82 mounted in fixed end bearings in the machine. The shaft 82 has secured thereto, at each end of the machine, a forwardly-extending lever 83 bearing on a seat 136 on the buffer 19, so that rotation of lever 79 causes a downward travel of this buffer.

The cross shaft 58 also carries slidably thereon a sleeve 84 having an arm 85 carrying a roller 86 which travels over the marginal part of the outer face of cam 73. This marginal part is formed with a depression 106 and, when the roller 86 runs over this, a spring 137 disposed around shaft 58 becomes effective to shift sleeve 84 and sleeve 57 to the left in Figure 3. As will be observed, the sleeve 57 is formed with an end spigot 138 which extends into a bore 147 in sleeve 84,

flanges

148 and 149 on the spigot and sleeve respectively serving as abutments for a light return spring 150. The leftwards movement of the parts carries the plunger 56 clear of nose 55, so releasing plunger 52. As will hereinafter be explained this also serves to set the parts ready for op eration of the power clutch when the treadle is next actuated.

It is also to be noted that the abutment element 50 co-operates with a spring-pressed sliding plunger 87 mounted in a bore 88 in a bracket 89 on the front wall 54 of the clutch box 27. As will be observed from Figure 9, in conjunction with Figure 4, when the abutment element 47 is rotated, as above described, to bring the approach clutch into operation, the crescent shaped element 50 rides over the head of plunger 87 and releases it so that it can lift under the action of its spring 99, thus locking the element 50, and hence element 47, against return movement. Consequently, the shifting of sleeve 57 and its plunger 56 as just described will not immediately result in a return swing of element 47 owing to the absence of pressure on nose 55.

The bracket 89 also carries a pair of spaced lugs 91 between which is pivoted a rocking arm 92 having a bifurcated end embracing the corresponding, pin-provided, end of plunger 87. The arm 92 has a lateral branch 93 which serves for the loose mounting of a roller 94.

' As will be hereinafter explained, operation of the branch piece 93 is used towithdraw plunger 87 and thus allow the approach clutch to be resetin its inoperative position.

It is further to be appreciated that, as the loose clutch element 42 turns withfastelement37, as above described, the head 45 of its sliding'bolt eventually, after approximately 180 travel of the element 42, rides over the oblique surface (corresponding-to. 72) of the abutment element 50, wherebythe bolt is again retracted and the drive through the approach clutch broken, thereby'terminating the approach stroke of'the buffer.

The powerclutch, which occupies the left hand portion of the clutch box 27 is similar to the approach clutch in that it includes'an abutment element 95 of crescent shape co-operating with theahead 96 of a bolt97 slidable in a bore in a'loose clutch element 98, to enable the latter tobe engaged with, or disengaged from, the passing dog 41 on the fast clutch element 37.

The abutment element 95, however, is only equivalent to the element 47- of the approach clutch and is not at tached to any counterpart of element 50. Itis pivotally mounted on a boss 99 and has secured thereto aspigot or casing 100 containing a spring pressed plunger 101 similar to that .(52) of the approachclutch. In addition the abutment element 95 is formed with a cranked extension 102 (see Figure 8) having therein a set screw 103 for adjustably limiting the .throw of this abutment element.

When the assembly of the sleeve 84, and sleeve 57, are in their right-hand position, as indicated in Figure 3, the power clutch is inoperative. When, however, at the end of the approach stroke this assembly is allowed to shift to the left (in Figure 3) as above described, the

sleeve 57 is moved into a position as illustrated inFigure 7, i. e. in which a nose 109 on spigot sleeve 100lies in the path of travel of the plunger 56.

Consequently, when lever 61 isnext operated by depression of a treadle, the plunger 56 will be moved, thereby to abut nose 109. on sleeve 100, thereby to cause abutment element 95 to rotate about itspivot 99. As a result, the head 96 of the bolt in the element 98 of'this clutch will ride on the inclined surface 110 of the abut ment, thereby to allow the bolt 97 .to be projected so that the nose is engaged by the dog 41 and the drive now made through the power clutch.

The clutch element 98 carries a cam disc 111 having therein a recess 107 .and over which runs a .roller 112 mounted on an arm 113 secured, by means of a sleeve 114 thereon, to a transversespindle :115 mountedfor rotation between the front and rear walls of the box 27. The arm 113 also rigidly incorporates a transverse sleeve 108 having therein a spring-pressed plunger 144 (smiliar in principle to the

elements

51, 52 and 100, 101), which plunger bears against the wall of the clutch box and thereby urges the roller 112 at all times into contact with cam disc 111 so as to follow the surface contour thereof.

The spindle 115 projects rearwardly out of the box and has secured to its outer end a curved arm 116serving as a means for interposing distance pieces into position for transmitting a drive from the main shaft 33 to the buffer 19 in performance of the power stroke of the press. Consequently, rotation of spindle 115, caused by roller 112 running down recess 107 as the disc 111 turns, produces a swing of arm 116.

This arm 115 has articulated tothe lower end thereof (see Figure l) a rod '117 which isslidable through a stud 118 secured between two longitudinal, parallel, spaced bars 119 which serve to interconnect two spaced rectangular blocks 120 mounted at the upper side of the buffer 19 and which are retained 'in correct relationship by cross pieces 145. It will be noted that the outer end of rod 117 has a head 121 bearing on a spring122 applied against the stud 118, this providing a safety device should the blocks 120 be obstructed for any reason.

The main drive shaft 33 has loose thereon a pair of spaced eccentric straps 123 which, at their lower ends, each have a nose 127 formed with a lateral arm 124 carrying a roller 125 moving. between a fixed pair of vertical guide bars 126. Normally, therefore, when the power clutch is out of operation, the noses 127 of each of the eccentric straps will carry out a reciprocating vertical movement against no opposition. When, however, the power clutch is brought into operation, and the arm 116 moved clockwise (as referred to Figure l), the result is to bring the distance blocks 120 into position beneath the respective eccentricstrap. noses .127 so 6 that, wl;1en-these lattennext contact the blocks, they will serveto force the buffer 19 downwards toperform the required power stroke.

Referring back to Figures 7 and 8, it is to be noted that the loose clutch-e1ement98 also has connected thereto a sleeve element with a nose, seen at 129 in Figure 8, which isarranged to co-operatewith the roller 94, so as, at the appropriate time, to act on this roller thereby to withdraw plunger 87 (see Figure 9) and allow restoration"? its originalnon-operative position of the approach clutc By a further-feature of this invention, such disengagement of the approach clutch can also be effected by an over-riding control operated from a knee bar 130 (see Figure 2) mounted on a pair of spaced rocking levers 142 which are connected, through Bowden cable 151 to a tail portion 143 of arm 92 projecting through the casing of box-27.

The operation of the machine has already been referred to in the foregoing description, but may now be summarized as follows:

The operator first lays the material to be cut on a cutter block on'the bed 4 of the machine and places the press knife thereon. He then depresses the .treadle 71 once, thereby pivoting abutment element 47 (together with element 50) of'the approach clutch to release bolt 44 for engagement with the dog 40. On such engagement, the element 42 turns and the arm 79 is operated to eifectthe approach'stroke. On release of the treadle by theoperator the abutment element 42 does not swing back to its original-position owing to the interposition of stop 87 in the return path of element 50. However, after the clutchelement has rotated 180, the bolt 44 is withdrawn by'element 50'and the approach clutch becomes inoperative. in the meantime the plunger 56 has been shifted by the face cam 73, as above described, from'the approach clutch into position in the power'clutch.

The length of the approach stroke of the buffer is adjustable, when the machine is at rest, between say 3.50" and 2.75, so that at the bottom of this stroke the working'face of the buffer descends to within, say 0.25 to 1.00" of the top of the knife, less the actual thickness of the material being cut.

The-operator is now in a position to effect the power or actual cutting stroke. This-he does by again depressing the treadle, which trips abutment element so causing loose element 98 to be rotated through 360 and the buffer to perform the power-phase of its stroke, as-indicated above, through the movable blocks and eccentric straps 123. After theloose clutch element 98 has performed approximately one complete turn, the bolt 97 is withdrawn by abutment element 95, which in the meantime has beenallowed to resume itsoriginal position, by virtue of the release of the treadle.

During this rotation of the element 98, moreover, the nose 129 has rocked the lever 92 to withdraw plunger stop 87 and thus allow resetting of the parts of the approach clutch and hence restoration of the plunger 56 to its initial position.

Conveniently-the total stroke of the buffer, i. e. the approach plus power strokes is 3.75" so that the power stroke required is'between 1.00 and 0.25. The noses 127 of the eccentric straps are, however, designed to produce a stroke-of, say, 2.00", but are arranged only to be in contact with-the distanceblocks 1-20 for not more than one half a revolution ofthe main shaft 33, viz. from 90 to 270. Moreover the auxiliary shaft 28 is so timed and the cam recess 107 in'the power clutch so shaped that the distance blocks are moved from their inoperative-to their operative positions in the period from the 20 to the 70 cam positions, i. e. before the noses 127 on the eccentric straps are due to contact them. This cam recess 107 is also-shaped so that the distance blocks.

will be returned to their inoperative positions in the 280 to 330 period, i. e. after the eccentric straps have lost contact with them.

The nose 129 and the parts operated thereby are designed so that the stop plunger 87 will be operated between the 330 and 360 positions to the buffer to 'be returned by its springs, to its top neutral position.

The above gives a summary of the normal working of the press which, however, also incorporates, as an important feature, the safety mechanism operable by safety knee bar 130. Hence if, at the end of the approach stroke, the operator has, say, .trappedhis fingers in the daylight of the press, or for any other reason wishes to discontinue the down-stroke of the buffer 19, he has simply to operate the knee bar 130. This exerts an overriding control on the stop plunger 87, causing it to be moved out of the way of abutment element 50 and allowing the buffer to be returned to its top position under spring action without performance of the power stroke.

'The press described has a number of advantageous features including the following:

(1) The two-stage operation of the form described not only permits the incorporation of a safety device, but also enables the press to have a good dayllght for handling of the material and the one or more knives, dies, or the like used.

(2) This safety device is positive and convenient, and is brought into effect with a minimum expenditure of human energy.

(3) Since only a buffer, and not the whole head, performs the downward movement there is no great inertia or power consumption, and the emergency arrest becomes quickly effective.

(4) By using a bed which is relatively long (e. g. 72 it is possible to work on a substantial length of material, so that there is no need to move the latter between cuts.

(5) By virtue of the small width (e. g. 8") there Is little obstruction of overhead lighting.

I claim:

1. A press having a frame, a movable buffer gulded in said frame, a counter surface for recelving work and cooperating with said buffer, and drive means therefor, such drive means including means operable to transmit an approach press-closing stroke towards said counter surface to said buffer from the drive means, means controlled in response to the operation of the approachstroke-transmitting means to transmit a subsequent power stroke to said buffer from the drive means, and means for precluding, at will, the drive coupling between the drive means and the power-stroke-transmltting means.

2. A press having a frame, a movable buffer guided 1n said frame, a counter surface for receiving work and cooperating with said buffer, and drive means therefor, such drive means including a first clutch for lmparting an approach stroke to said buffer, a second clutch controlled in response to the operation of the first clutch for 1mparting a power stroke to said buffer and means operable to bring said clutches separately into operation.

3. A press having a frame, a fixed head, a movable buffer received in said frame below said head, a fixed bed in said frame, a main drive shaft, and drive means therefor, such drive means including first and second mechanical transmissions disposed to act on said buffer, an approach clutch operable to connect the dr1 ve from said main shaft to the first mechanical transmiss on, a power clutch controlled in response to the operation of the approach clutch to connect the drlve from the main shaft to the second mechanical transmisslon and means for precluding the operation of said power clutch.

4. A press as defined in claim 3, 1n which the approach and power clutches are comb ned into a unitary assembly removably mounted in said fixed head of the press.

5. A press as defined in claim 4, 1n WhlCh the clutch assembly comprises an auxiliary shaft adapted to be driven from the main shaft and common to the two clutches, a driving clutch element secured on the auxiliary shaft for rotation therewith and common to the two clutches, a loose clutch element in each of said clutches and respectively adapted to operate said first and second mechanical transmissions, and actuating means shiftable from one clutch to the other to control the operation of the respective loose clutch element.

6. A press as defined in claim 5, 1n WhlCh each clutch comprises a clutch element normally loose on the auxiliary shaft, a retractible bolt slidably carried by this loose clutch element and an abutment element movable to project said bolt for engagement with said driving clutch element.

7. A press as defined in claim 6, further including a stop normally preventing restoration of the approach clutch abutment element after operation of the latter but movable into ineffective position by said power clutch, and a safety device operable to move said stop into ineffective position irrespective of the operation of the power clutch.

8. A press having a frame, a movable buffer guided in said frame, a counter surface for receiving work and cooperating with said buffer, and drive means, said drive including a first clutch for imparting an approach stroke to said buffer, a second clutch controlled in response to the operation of the first clutch for imparting a power stroke to said buffer, and a safety device controlling the operation of said second clutch.

9. A press having a frame, a movable buffer guided in said frame, a counter surface for receiving work and cooperating with said buffer, a main drive shaft, and drive means therefor, such drive means including first and second mechanical transmissions disposed to act on said buffer, an approach clutch operable to connect the drive from said main shaft to the first mechanical transmission, said first mechanical transmission comprising a lever system operable on the buffer and a control eccentric rotatable with said approach clutch, and a power clutch controlling in response to the operation of the approach clutch to connect the drive from the main shaft to the second mechanical transmission.

10. A press having a frame, a movable buffer guided in said frame, a counter surface for receiving work and cooperating with said buffer, a main drive shaft, and drive means therefor, said drive means including first and second mechanical transmissions disposed to act on said buffer, an approach clutch operable to connect the drive from said main shaft to the first mechanical transmission, a power clutch controlled in response to the operation of the approach clutch to connect the drive from the main shaft to the second mechanical transmission, an auxiliary shaft adapted to be driven from the main shaft and common to the two clutches, a driving clutch element secured on the auxiliary shaft for rotation therewith and common to the two clutches, a loose clutch element in each of said clutches and respectively adapted to operate said first and second mechanical transmissions, a retractible bolt slidably carried by this loose clutch element and an abutment element in each said clutch movable to project said bolt for engagement with the driving clutch element, the abutment element of the approach clutch having rigid therewith an auxiliary abutment element oscillatable with the former about a common pivot, and the approach clutch and auxiliary abutment elements each having a cam surface for withdrawing the corresponding bolt at appropriate times.

11. A press having a frame, a movable buffer guided in said frame, a counter surface for receiving work and cooperating with said buffer, a main drive shaft, and drive means therefor, said drive means including first and second mechanical transmissions disposed to act on said buffer, an approach clutch operable to connect the drive from said main shaft to the first mechanical transmission, a power clutch controlled in response to the operation of the approach clutch to connect the drive from the main shaft to the second mechanical transmission, an auxiliary shaft adapted to be driven from the main shaft and common to the two clutches, a driving clutch element secured on the auxiliary shaft for rotation therewith and common to the two clutches, a loose clutch element in each of said clutches and respectively adapted to operate said first and second mechanical transmissions, a face cam rotatable with the loose clutch element of the approach clutch and an actuating plunger movable by said cam from the loose clutch element of the approach clutch to the loose clutch element of the power clutch.

12. A press having a frame, a movable bufier guided in said frame, a counter surface for receiving work and cooperating with said buffer, a main drive shaft, at least one eccentric rotatable with said main shaft, and drive means therefor, said drive means including first and second mechanical transmissions disposed to act on said buffer, an approach clutch operable to connect the drive from said main shaft to the first mechanical transmission, and a power clutch controlled in response to the operation of the approach clutch to connect the drive from the main shaft to the second mechanical transmission, said second mechanical transmission including at least one distance piece shiftable on the buffer into and out of drive transmitting position under command of the power clutch.

13. A power press as defined in claim 12, in which the second mechanical transmission includes a lever 10 fystem 1opeiiablle by a cagilfsecueg to the power )clutch References Cited in the file of this patent oose c utc e ement to s t sai istance piece s 14. A power press as defined in claim 13, in which UNITED STATES PATENTS said eccentric comprises a strap with a nose guided for Number Name Date 5 364,142 Stiles May 31, 1887 vertical reciprocating movement.

2,185,551 Glasner et a1 Jan. 2, 1940