US2744304A - Tandem toggle press - Google Patents

Description

May 8, 1956 J. 1. KAUL TANDEM TOGGLE PRESS 5 Sheets-Sheet 1 Filed Dec. 20. 1952 Em-TE:

In n rl-lI-IF INVENTOR. JOSEPH J. K/IUL ,477'02A EY5 May 8, 1956 J 1, KAUL TANDEM TOGGLE PRESS 5 Sheets-Sheet 2 Filed Dec. 20, 1952 INVENTOR. .7061 5/ /1 1'. (Al/L A FOE/V675 May'8, 1956 J. l. KAUL TANDEM TOGGLE PRESS 5 Sheets-Sheet 3 Filed Dec. 20, 1952 IN V EN TOR.

JOSEPH I- KAI/L A TTOR/VEYS May 8, 1956 J. l. KAUL TANDEM TOGGLE PRESS 5 Sheets-Sheet 4 Filed Dec. 20, 1 952 5 m a TA M M 2 W m 1 W A w M V. B

May 8, 1956 J. l. KAUL TANDEM TOGGLE PRESS 5 Sheets-Sheet 5 Filed Dec. 20 1952 0 a y NA M W M 7 m M N w E w J United States Patent ments, to National Lead Company, New York, N. 1., a corporation of New Jersey Application December 20 1952, Serial No. 327,193

' Claims. (Cl. 22-'92) This invention relates to presses, particularly for closing molding dies, and more particularly to presses of the toggle type. Toggle presses are well known and widely used to open and close a molding die, both for the die casting of metal and the molding; of plastics. The usual press comprises a stationary plate, an end frame or crab, machine bars extending from saidstationary plate to said crab, a sliding plate slidable on said machine bars, a toggle linkage between. the crab and the sliding. plate, a closing means, usually a closing cylinder, carried by the crab and acting on a piston and piston rod connected to a crosshead whichin turn is connected to the toggle linkage to either fold the linkage when opening the die, or to straighten or close the linkage When closing the die. Byuse of the toggle linkage the closing cylinder may be of small diameter instead of large diameter, thereby conserving in the use of hydraulic power.

However, as these toggle presses are inereasedim dimension-to handle larger and larger dies difiiculty arises in obtaining adequate die opening movement or travel. For example, in toggle presses of one known design a 21" machine (meaning that the transverse: distance between the machinebars is 21") has a-dieopeningtravel: of about 17 ",but a 28 machine has a die opening-travel. of only 18", and a 48" machine has a die openingttra'vel of only The travel is limited by the toggle linkagebecause in a large machine for alarg'edie the die closing force needed is so great that the toggle links become:

heavy and cumbersome and the link 'pins become large in diameter, in consequence of which there is less "roomfor the toggle linkageto fold up. The problem is aggravated byv the fact that in large machines it -heconies'desirable to apply the toggle pressure medially'tothe s'lidi'ng 'plate instead of at the outside edges, in order to avoid p'os sible warping or bending'ofth'e' sliding plate itself.

One object'of the present inx' e'ntion is'to' overcome the opening travel of, say, 36'', it would be wasteful of hydraulicpower to use sucha-macliine in the many cases where a die opening travel of only 20" is needed. In-

accordance with a further feature and object ofm-y inv'e'm tion a toggle press is provided which will ethciently pro vide a smaller 'dieopening travel when that is adequate;

and a larger die'opening travel when needed, the travelbeing adjustable to intermediate amounts between: the" minimum and maximum travel.

To accomplish the foregoing general object's; andother more specific objects which will her'einafter' appear', my" invention residesirr the tandem' toggle press elements, and their relation one to anothen as -ar e hereinafter more par: ti'c'ularl'y described in the: following;specification The specificatiom is accom anied by'drawiiigs; i -wnieir: v

ICC.

Fig. 1 is a plan view of a cold chamber die casting machine embodying features of my invention;

Fig. 2 is a side elevation thereof;

Fig. 3 is" a horizontal section taken approximately in the plane of the line 33' of Fig. 2, butwiththe cold chamber shot mechanism omitted; I

Fig. 4 is a side elevation showing. the relation ofthe parts with the front toggle linkage folded and the back toggle linkage closed, for a small die opening travel;

Fig. 5 is a similar side elevation showing the front toggle folded and the back toggle linkage partially folded for an' intermediate amount ofdie opening travel;

Fig. 6 is a horizontal section taken approximately in the plane of the line 6-6 of Fig. 4;,

Fig. 7 is a horizontal section taken approximately in the plane of the line 7-17'of Fig. 5;

Fig. 8 is a side elevationshowing the relation of the parts with both toggle-linkages folded for maximum die opening travel; and v Fig. 9is a section taken approximately in the plane of the line 9-9 of Fig." 8.

Referring to the drawing, and more particularly to Figs. 1, 2 and 3 thereof, the tandem toggle presscomprisesa stationary plate 12,.a sliding plate 14,:an end frame or crab 16,.anda'slidable center frame 18 disposed between the crab 16 and the sliding. plate 14. There is a front toggle linkage generally designated 2t) mounted-between the center frame 18 and the sliding, plate 14,.and afront crosshead. 22 for operating the front linkage 20. In accordance with the-present invention thereis-a-secondor back toggle linkage generally designated 24 mounted-between the crab 16 and the center frame '13,- and aback crosshea'd26for operating the back linkage. 2-4: A clos ingmea'n's 28' is mounted on the crab 16 and-actson a rod 30' Which is slidable through theback. crosshead Z6- and connected to the front crosshead 2 2. As is most clearly shown in Fig. 3, there are. spaced collars-32 and 34 on the rod 30, andthese provide alostmotioncon-" nection'to the back crosshead 26. The rod 30*issecuredto the front crosshead 22, asi ndicatedat- 36. Therear collar 32 is so located that-when the rodSti-moVes to the right or in closing. direction both toggle linkages simulta* neously reachtheir closed or locked positions; shownin Fig; 2. The front collar 34 is so locatedon rod 30- that when moving tothe left-or in opening di rection the backcrosshead 26 is notmoved until later than" the front crosshead 22' butbefore the front crosshead reachesthe center frame 18. More specifically,,the'timingis-suchas to cause full folding.of bothtoggle-linkages; as is: best shown" in Fig. 8,. and full closing. or locking ofboth linkages, as'sho'wn in Fig. 2. T I

Considering Figs; 1, 2 and 3 in somewhat greater detail, there are four main tie rods or machine bars 40 extending from the stationaryplate12 to the crab 16, and the sliding plate 14is slidable onthe'machinebars 40'. When the machine is a horizontal 'machine, as here shown, the stationary plate'lz' may be fixedly mounted on track rails 42' (Fig. 2) as shown at 44', and the sliding. plate 14 may be provided with rollersddrunning' onthe track rails 42. The'crab 16 is'locked in position on themacihne'bars- 40' by 'means' of nuts 48, and" it will b'e' under sto'od that by shiftingthe position. of the" nuts" 48 along the' machineba'rs the spacing between the statio'nary and sliding plates Hand 14 may be varied to fitthe" size" of the die being mounted in the press. Thus in the present case the die shown inbroken lines comprises a'cover' die50 and'an ejector die '52 "separable at-apartingface'-54: The cover-"die50'is' mountedonstationary plate 12, and theejector die 52, together with its ejector block or mecha are so adjusted that thedie: is tightly closed when" the toggle linkages are in the closed position shown. To facilitate this adjustment the crab 16 is also mounted on rollers indicated at 53 and 60 in Fig. 2.

The closing means 28 comprises an hydraulic cylinder operating on a piston 62 connected to the rod 30.

The front toggle linkage 20 comprises front links 64 pivotally connected to the sliding plate 14, and back links 66 pivotally connected to the center frame 18. The links 64 and 66 are also pivotally connected to one another and to spreader links or center links 68, the inner ends of which are connected to the crosshead 22. The back toggle linkage 24 may be identical with the front toggle linkage.

The crossheads 22 and 26 are preferably slidably mounted on sliding rods or crosshead guides 76, best shown in Figs. 3, 6, 7 and 9. These may be secured at their forward ends to the sliding plate 14, and may pass slidably through the crosshead 22, the center frame 18,

the crosshead 26, and the crab 16. It is customary to ernpiston drives a crosshead 7 connected to a shot plunger 73. The chamber and cylinder and crosshead guides are secured to the stationary plate in any suitable manner, here exemplified by tie rods 76 extending from the shot cylinder 74 to the stationary plate 12, and by pedestal 75.

One main advantage of the present tandem toggle press is that a reduced die opening travel may be provided when desired. This is illustrated in Figs. 4 and 6 which show the relation of the parts when using only one of the two toggle linkages. Thus in Fig. 4 it will be seen that the front toggle linkage 20 is folded, while the back toggle linkage 24 is closed. To obtain this result the back linkage is fixed in its locked position, and even more directly, the center frame 18 is locked in its forward position. For this purpose optionally usable split nuts 39 are applied to the threaded region 82 on the machine bars 40, thus fixing the center frame 18 in its forward position, and causing it to act as though it were the stationary or end frame of a single toggle press. At this time the crab 16, the closed toggle mechanism 24, and the center frame 18 all remain in fixed relation as though they were but a single end frame assembly.

Referring to Fig. 6, it is important to note that while the back collar 32 of the spaced collars on piston rod 349 may be left in position as shown, the front collar 34 shown in Fig. 3 has now been removed, thereby exposing in Fig. 6 an annular channel at 84. This channel receives the split collar 34 when the latter is being used. It will be understood that at this time the front crosshead 22 is in use, whereas the back crosshead 26 is not, and con.- sequently the piston rod 30 is permitted to slide freely through the idle hack crosshead. For this purpose the spaced collars 32 and 34 both might be removed, but I prefer to remove only the front collar 34, because the back collar 32 does no harm, and indeed when moved to its forwardmost position, reaches and bears against the back crosshead and thereby may be used to help insure maintenance of the back toggle linkage in its closed position.

In Fig. 6 it will be seen that the die opening travel is positively limited because the front crosshead 22 reaches the fixed center frame 18, which then acts as a positive stop for the crosshead. The piston 62 has traveled only part of its permissible travel in cylinder 28, but cannot move further. There is a consequent saving of hydraulic Figs. 3

power, when the partial opening shown is adequate for the work being done.

If a die opening travel of intermediate amount is wanted, that is, greater than the travel shown in Fig. 4 but less than maximum, the relation of the parts is that illustrated in Figs. 5 and 7 of the drawing. In Fig. 5 it will be seen that the front toggle linkage 20 has been fully folded, while the rear toggle linkage 24 has been only partially folded. In this case the split nuts 80 shown in Fig. 4 are removed, thus permitting sliding movement of the center frame 18. The split collar 34 is restored, thus again providing a pair of spaced collars 32 and 34 for lost motion operation of the back crosshead 26. However, optionally usable stops 36 (Fig. 7) are employed to limit the rearward travel of the crosshead 26, and consequently of the piston 62. The stops 86 may be horseshoe-shaped stops which are secured around the crosshead guides 79 previously referred to. They are interposed between the stationary crab 16 and the crosshead 26. It will be understood that these stops may be provided in varying lengths, thus making it possible to provide adequate but not excessive die opening travel for any particular die mounted in the press.

Maximum opening of the press is illustrated in Figs. 8 and 9 of the drawing. At this time the horseshoe-shaped stops 86 of Fig. 7 are, of course, removed from the cross head guide rods '70. The split nuts 80 shown in Fig. 6 are also not in use. Optionally usable spaced collars 32 and 34 are employed on the piston rod 30. The arrangement then permits complete folding of both the front and back toggle linkages, as shown in Fig. 8, and at this time the back crosshead 26 reaches the crab 16 which acts as a motion limiting stop. The piston 62 has almost reached the end of cylinder 28. The front crosshead 22 has almost reached the center frame 18, but there is preferably a slight clearance therebetween.

It will be understood that the installation or removal of the optionally usable parts is the same in Figs. 8 and 9 as was described in connection with Figs. 1, 2 and 3, but in the latter figures the press is shown fully closed, while in Figs. 8 and 9 the press is shown fully open. It will be understood, however, that the closed relation of the toggle linkages shown in Figs. 1, 2 and 3 is also applicable to the press when arranged as described in connection with Figs. 4 and 6, and also when arranged as described in connec tion with Figs. 5 and 7, but for purposes of illustration the split nuts 80 and the horseshoe-shaped steps 86 have been omitted in Figs. 1, 2 and 3, and in that sense the figures correspond to Figs. 8 and 9 of the drawing.

By way of specific example, but not in way of limitation of the invention, 1 may mention that in one specific press embodying my invention the machine had a transverse spacing between machine bars of 72" and was capable of taking dies ranging from 30" to 56" in height, meaning the horizontal dimension of the die when the parting face is vertical, as shown in the present drawings. The die opening travel ranged from 20" when using only the front toggle, as shown in Fig. 4, to 36" when using both toggles, as shown in Fig. 8. I may mention, however, that in that particular press the toggle links were disposed in known angular relation and connected medially to the frames and sliding plate, that is, there were four toggle linkages extending radially outward from the crosshead, instead of top and bottom linkages as here shown. The machine here illustrated has been selected because the drawings are far simpler and clearer than is the case when attempting to illustrate angularly disposed linkages. The principles of the tandem toggle operation are the same in either case.

It should be understood that the tandem toggle linkage here shown differs from the use of toggle linkages in series for increased power. This is not a machine in which a piston closes a first toggle linkage, which in turn acts to close a second toggle linkage, thereby multiplying the force exerted. In the present case it might be said that the toggle linkages act 'inpara'llel rather thanin'serie's', though somewhat "displaced in phase.

' It should also be understood that the situation isnot as simple as-though providing a direct connection between the piston rod and spaced crossheads, without the' lost motion connection here shown. It is merely necessary to compare Fig. 3 with Fig. 9, forif the piston rod 30 were permanently secured tothe crossheads 22 and 26 at the spacing shown in Fig. 3, one would not obtain the maximum die opening shown in Fig. 9 in which the spacing between crossheads 22 and 26 is far less than that shown inv Fig. 3. The situation is also not as simple as though it'were attempted to begin opening of the'back toggle linkage after completing opening of 'the front toggle linkage. This may be understood by reference to Fig. 4

because when the front crosshead 22 has reached the center frame 18 it is no longer possible for the piston rod 30'to open the back toggle linkage 24. This would be true even without using the split nuts 80, for his inherent in the operation of a toggle linkage'that' considerable travel of the crosshead is needed'for' only slight movement ofthe plate when first opening the toggle, whereas toward the end the motion of the plate is accelerated. If the opening of the back toggle linkage were delayed until completionrof the opening of the front toggle linkage the piston rod movement then needed would greatly exceed the movement of the center frame 18, and consequentl the back toggle linkage could not be opened.

It is accordingly necessary for the toggle opening movements-to overlap enough to afford some initial opening of the-back toggle while the folding of the front toggle is still taking place, and some additional final folding of the front toggle may take place during folding of the back toggle, with the timing such that both reach folded I condition at substantially the same time, as shown in Fig.

8'. Similarly, the'timing is such during the closing opera tion that both reach the closed or locked position shown in Fig. 2 at substantially the same time. This istaken care of by appropriate location of the collars'32 and 34 on the piston rod 30. It is with these considerations in mind that I thinkof the tandem toggles as'being operated in parallel but with a difference in phase, the'latter. being determined by the location'of' the collar 34 on'the piston rod 30.

It. may be mentioned that the die opening travel shown in Figs. 4 and 6.is not the minimum possible. In rare cases one might work with a die requiring even less opening, and it will be understood that in such case appropriatestops may be used to further limit. the travel of the sliding. plate 14. More specifically, I may simply use some of the horseshoe-shaped. stop 86v previously described in connection with- Fig. 7 as being. used between the rearcrosshead 26 andthe end frame 16, but such stops'would now be placed between the front crosshead 22- (Fig, 6). and the then stationary or locked center plate'18. The stops would, of course, be disposed on the slide bars 70, as was explained in connection withFig. 7. These stops 86 are anyway available'in different lengths'for. use

at the point indicated in Fig. 7, and a selected pair of stops of appropriate length could equally well beused behind the front crosshead 22 with the press otherwise-arranged as shown in Fig. 6. In this way any desired die opening travel may be obtained, although, as already indicated; for most practical purposes the adjustment of travel to the range is in increments between that'shown in Fig. 6 to that shown in Fig. 9.

"It is believed that the construction and operation and.

method of use of. my'improved tandem toggle press, as well as:-the many advantages thereof, will be" apparent from theforegoingdetailed description. It willi also be apparent thatwhile I have shown and described my inven-- tion in a preferred form, changesmay be made in the structure shown without departing from the scope of the invention, assou'ght-to be defined in the following claims.

toggle linkage between said center frame and said sliding plate, a front crosshead for operating the same, back toggle linkage between said crab and said center frame, a back crosshead for operating the same, a closing means carried by said crab and acting on a rod slidable through said back crosshead and connected to said front crosshead, spaced collars mounted on said rod and providing a lost'motio-n connection to said back crosshead, the spacing of the collars being such that in opening direction the back crosshead is moved later than the front crosshead and before the front crosshead reaches the center frame.

2. A tandem toggle press comprising a stationary plate, a sliding plate, an end frame or crab, a slidable center frame between said crab and said sliding plate, front toggle linkage between said center frame and said sliding plate, a front crosshead for operating the same, back toggle linkagebetween said crab andsaid center frame, a back crosshead for operating the same, a closing means carried by said crab and acting on a rod slidable through said back crosshead and connected to said front crosshead, spaced collars mounted on said rod and providing a lost motion connection to said back crosshead, the spacing of the collars being such that in opening direction the back crosshead is moved later than the front crosshead and before the front crosshead reaches the center frame, and optionally usable stop means to stop the back crosshead after it has opened the back toggle only partially.

3. A tandem toggle press comprising a stationary plate, a sliding plate, an end frame or crab, a slidable center frame between said crab and said sliding frame, front toggle linkage between said center frame and said sliding the front crosshead and before the front crosshead reaches the center frame, and optionally usable means to fix the back toggle in closed or locked position.

4. A tandem toggle press comprising a stationary plate, a sliding plate, an end frame or crab, a slidable center frame between said crab and said sliding plate, front toggle linkage between said center frame and said sliding plate, a front crosshead for operating the same, back toggle linkage between said crab and said center frame, a back crosshead for operating the same, a closing means carried by said crab and acting on a rod slidable through said back crosshead and connected to said. front crosshead, optionally usable spaced collars mounted on said rod and providing a lost motion connection to said back crosshead, the spacing of the collars being such that in opening direction the back crosshead'is moved later than the front crosshead and before the front crosshead reaches the center frame, optionally usable stop means to stop the back crosshead afterv it has opened the back toggle only partially, and optionally usable means'to fix the back'toggle in closed or locked position.

5. A tandem toggle press comprising a stationary plate, a sliding plate, an end frame or crab, a slidable center frame between said crab and said sliding plate, from piston rod slidable through said back crosshead and connected to said front crosshead, spaced collars mounted on said piston rod and providing a lost motion connection to said back crosshead, the spacing of the collars being such that in opening direction the back crosshead is moved later than the front crosshead and before the front crosshead reaches the center frame, and in such timing as to cause full folding of both toggle linkages, and such that in closing direction both toggle linkages reach their closed or locked positions at the same time.

6. A tandem toggle press comprising a stationary plate, a sliding plate, an end frame or crab, a slidable center frame between said crab and said sliding plate, front toggle linkage between said center frame and said sliding plate, a front crosshead for operating the same, back toggle linkage between said crab and said center frame, a back crosshead for operating the same, a closing cylinder carried by said crab and acting on a piston and piston rod slidable through said back crosshead and connected to said front crosshead, spaced collars mounted on said piston rod and providing a lost motion connection to said back crosshead, the spacing of the collars being such that in opening direction the back crosshead is moved later than the front crosshead and before the front crosshead reaches the center frame, and in such timing as to cause full folding of both toggle linkages, and such that in clos ing direction both toggle linkages reach their closed or locked positions at the same time, and optionally usable stop means to stop the back crosshead after it has opened the back toggle only partially.

7. A tandem toggle press comprising a stationary plate, a sliding plate, an end frame or crab, a slidable center frame between said crab and said sliding plate, front toggle linkage between said center frame and said sliding plate, a front crosshead for operating the same, back toggle linkage between said crab and said center frame, a back crosshead for operating the same, a closing cylinder carried by said crab and acting on a piston and piston rod slidable through said back crosshead and connected to said front crosshead, optionally usable spaced collars mounted on said piston rod and providing a lost motion connection to said back crosshead, the spacing of the collars being such that in opening direction the back crosshead is moved later than the front crosshead and before the front crosshead reaches the center frame, and in such timing as to cause full folding of both toggle linkages, and such that in closing direction both toggle linkages reach their closed or locked positions at the same time, and optionally usable means to lock the center frame in its forward position.

8. A tandem toggle press comprising a stationary plate,

a sliding plate, an end frame or crab, a slidable center frame between said crab and said sliding plate, front toggle linkage between said center frame and said sliding plate, a front crosshead for operating the same, back toggle linkage between said crab and said center frame, a back crosshead for operating the same, a closing cylinder carried by said crab and acting on a piston and piston rod slidable through said back crosshead and connected to said front crosshead, optionally usable spaced collars mounted on said piston rod and providing a lost motion connection to said back crosshead, the spacing of the collars being such that in opening direction the back crosshead is moved later than the front crosshead and before the front crosshead reaches the center frame, and in such timing as to cause full folding of both toggle linkages, and such that in closing direction both toggle linkages reach their closed or locked positions at the same time, optionally usable stop means to stop the back crosshead after it has opened the back toggle only partially, and optionally usable means to lock the center frame in its forward position.

9. A tandem toggle press comprising a stationary plate, an end frame or crab, machine bars extending from said stationary plate to said crab, a sliding plate slidable on said machine bars, a center frame slidable on said machine bars between said crab and said sliding plate, front toggle linkage between said center frame and said, sliding plate, a front crosshead for operating the same, back toggle linkage between said crab and said center frame, a back crosshead for operating the same, crosshead guide bars passing through said crossheads, a closing cylinder carried by said crab and acting on a piston and piston rod slidable through said back crosshead and connected to said front crosshead, spaced collars mounted on said piston rod and providing a lost motion connection to said back crosshead, the spacing of the collars being such that in opening direction the back crosshead is moved later than the front crosshead but before the front crosshead reaches the center frame.

10. A tandem toggle press comprising a stationary plate, an end frame or crab, machine bars extending from said stationary plate to said crab, a sliding plate slidable on said machine bars, a center frame slidable on said hine bars between said crab and said sliding plate, in t toggle linkage between said center frame and said sliding plate, a front crosshead for operating the same, back toggle linkage between said crab and said center frame, a back crosshead for operating the same, crosshead guide bars passing through said crossheads, a closing cylinder carried by said crab and acting on a piston and piston rod slidable through said back crosshead and connected to said front crosshead, spaced collars mounted on said piston rod and providing a lost motion connection to said back crosshead, the spacing of the collars being such that in opening direction the back crosshead is moved later than the front crosshead but before the front crosshead reaches the center frame, and optionally usable stop means on said crosshead guides between said crab and said back crosshead to stop the back crosshead after-it has opened the back toggle only partially.

ll. A tandem toggle press comprising a stationary plate, an end frame or crab, machine bars extending from said stationary plate to said crab, a sliding plate slidable on said machine bars, a center frame slidable on said machine bars between said crab and said sliding plate, front toggle linkage between said center frame and said sliding plate, a front crosshead for operating the same, back toggle linkage between said crab and said center frame, a back crosshead for operating the same, crosshead guide bars passing through said crossheads, a closing cylinder carried by said crab and acting on a piston and piston rod slidable through said back crosshead and connected to said front crosshead, optionally usable spaced collars mounted on said piston rod and providing a lost motion connection to said back crosshead, the spacing of the collars being such that in opening direction the back crosshead is moved later than the front crosshead but before the front crosshead reaches the center frame, and optionally usable means mounted on said machine bars to lock the center frame in its forward position.

12. A tandem toggle press comprising a stationary plate, an end frame or crab, machine bars extending from said stationary plate to said crab, a sliding plate slidable on said machine bars, a center frame slidable on said machine bars between said crab and said sliding plate, from tog le linkage between said center frame and said sliding plate, a front crosshead for operating the same, back toggle linkage between said crab and said center frame, a back crosshead for operating the same, crosshead guide bars passing through said crossheads, a closing cylinder carried by said crab and acting on a piston and piston rod slidable through said back crosshead and connected to said front crosshead, optionally usable spaced collars mounted on said piston rod and providing a lost motion connection to said back crosshead, the spacing of the collars being such that in opening direction the back crosshead is moved later than the front crosshead but before the front crosshead reaches the center frame, optionally usable stop means on said crosshead guides between said crab and said back crosshead to stop the back crosshead after it has opened the back toggle only partially, and optionally usable means mounted on said machine bars to lock the center frame in its forward position.

13. In a die press, a fixed member for mounting a fixed die plate, an end frame or crab disposed in spaced relation to said fixed member, a sliding member for carrying a movable die plate, said sliding member being disposed between the end frame and the fixed memher, and means connecting said sliding member to the end frame for moving the sliding member toward and away from the fixed member, said means including a plurality of toggle linkages, a cross head for actuating each toggle linkage, and means connected to said crossheads for moving the same to actuate said toggle linkages, the last means being operable to move said crossheads sequentially such that in opening direction the crosshead most closely adjacent the end frame is moved later than the other crossheads and before the associated toggle linkages of the latter are completely collapsed.

14. In a die press, a fixed member for mounting a fixed die plate, an end frame or crab disposed in spaced relation to said fixed member, a sliding member for carrying a movable die plate, said sliding member being disposed between the end frame and the fixed member, and means connecting said sliding member to the end frame for moving the sliding member toward and away from the fixed member, said means including at least two toggle linkages and an intermediate sliding frame, one of the toggle linkages being connected between the sliding frame and the sliding member and the other toggle linkage being connected between said end frame and the sliding frame, a crosshead connected to each toggle linkage, and means connected to said crossheads for moving the same to actuate the toggle linkages, the last means being operable to move said crossheads sequentially such that in opening direction the crosshead connected to said other toggle linkage is moved later than the crosshead connected to said one toggle linkage and before the one toggle linkage is completely collapsed.

15. A die casting machine, comprising a fixed memher having a fixed die plate secured thereto, an end frame or crab disposed in spaced relation to said fixed member, a sliding member disposed between the end frame and fixed member and having a movable die plate secured thereto for movement between a position in which the die plates are in close contact and a position in which the die plates are out of engagement and spaced apart to permit the ejection of an article cast therebetween, and means connecting the sliding member to the end frame for moving the movable die plate away from the fixed die plate to the position which permits the ejection of the cast article therefrom, said means including a plurality of toggle linkages, a crosshead for actuating each toggle linkage, and means connected to said crossheads for moving the same to actuate the toggle linkages, the last means being operable to move said crossheads sequentially such that in opening direction the crosshead most closely adjacent the end frame is moved later than the other crossheads and before the associated toggle linkages of the latter are completely collapsed, and means for injecting molten material between the die plates.

References Cited in the file of this patent UNITED STATES PATENTS 1,954,775 During et a1. Apr. 10, 1934 2,113,033 Poole et al. Apr. 5, 1938 2,306,323 Schoepflin et al. Dec. 22, 1942

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