US 3611497 A
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Oct. 12, 1971 (3|DGE HAL 3,611,497
TIE-ROBLESS DOUBLE ACTING PRESS Filed May 1, 1969 3 Sheets-Sheet 1 INVENTUR.
Lester Gidge BY PM ""Paam-n A T TORNEYS Vulmor R. Poulin Jr.
a Sheets-Sheet 2 L. GIDGE ETAL TIE-RODLESS DOUBLE ACTING PRESS Oct. 12, 1971 Filed llay i, 1969 BY Volmor R. Poulin Jr. Flu/Am PM ATTORNEYS 12, 1971 L. GIDGE ETAL 3,611,497
TIE-RODLESS DOUBLE ACTING PRESS Filedua 1, 1969 3 Sheets-Sheet s INVENTOR. Le Gidge B V0 0 R. Poulin Jr.
ATTORNEYS United States Patent O 3,611,497 TIE-RODLESS DOUBLE ACTING PRESS Lester Gidge and Valmor R. Poulin, Jr., Nashua, N.H., assignors to Nashua Industrial Machine Corporation, Nashua, NH.
Filed May 1, 1969, Ser. No. 820,894 Int. Cl. 153% 1/16 US. Cl. 18.-16 T 8 Claims ABSTRACT OF THE DISCLOSURE A novel toggle press wherein the gross vertical movements of two movable platens is achieved with a single actuating ram by use of toggle assemblies and with each platen acting as a counterweight to aid in raising the other platen. This press utilizes auxiliary power means, independent of the single actuating ram, to apply molding pressure, and one embodiment of the invention this auxiliary power means is mounted on each toggle assembly and acts on a pivot pin attached to the upper platen assembly.
BACKGROUND OF THE INVENTION A considerable amount of effort has been expended over the years in providing improved compression molding apparatus. For example, such apparatus is described in US. Pat. 2,792,592 to R. G. McGee; US. Pat. 3,205,551 to R. Neubauer et al., and many others. Most such patents comprise tie-rods through the platens thereof to provide guidance for the platens on the opening and closing of the press. One said inventor, W. G. Corson, in apparatus described in US. Pat. 2,624,915, avoided the use of such tie-rods, but his was a special purpose press comprising only one moving platen assembly.
In general, all previous inventors have attempted to improve the mechanical advantage offered by such presses, or to improve the stroke length or compression rate for some special purpose. Nevertheless, all prior art presses have some drawbacks, and it has been a particular problem to provide a relatively inexpensive press in which a high mechanical advantage is achieved, and on which conventional tie-rods are avoided to maximize access to the work area. It has also been a problem to provide a press which can be opened and closed quickly and which has a platen-travel speed which is not limited throughout its travel by the limitations of the velocity of a conventional power stroke mechanism.
SUMMARY OF THE INVENTION It is an object of the instant invention to provide a novel toggle press with a highly efficient leverage system.
Another object of the invention is to provide a toggle press which does not require conventional tie-rods for guidance of the platens during the Opening and closing of the press, but on which press the levers of the toggle system provide a substantial part of the guidance for the platen assemblies.
Still another object of the invention is to provide a toggle press having excellent acceleration and deceleration characteristics on the opening and closing of the press.
A further object of the invention is to provide a Patented Oct. 12, 1971 ice toggle press whereby the mass of the bottom platen assembly thereof is utilized in lifting the mass of the top platen assembly thereof during the opening of the press, and where the mass of the top platen assembly is utilized in lifting the mass of the lower platen assembly during the closing of the press.
Another object of the invention is to provide a press wherein the velocity at which the platens are moved apart is substantially greater than is usual in such apparatus.
Other objects of the invention will be obvious to those skilled in the art on reading the instant application.
These objects have been substantially achieved by the construction of a novel toggle press comprising four multiple lever-type toggle assemblies which connect an upper platen carrier assembly and a lower platen carrier assembly. These connections are substantially at the corners of the platen assemblies and allow the toggle assemblies to serve effectively to guide the platens in their gross vertical movements, i.e. the movements which bring the platens back and forth between the open position and that position at which the compression or molding, stroke must begin. Each toggle system comprises a double-acting master lever attached to a fixed pivot on the fixed framework of the press apparatus. One end of this master lever is pivotally attached to the upper platen assembly. The other end of the master lever is pivotally attached to two additional levers, the first of which is pivotally attached at its opposite end to the press-actuating ram and the second of which is pivotally attached at its opposite end to the lower platen assembly. This lever arrangement provides a force-transfer means whereby potential energy being recovered from whichever platen assembly is being lowered is partly utilized to aid in raising whichever platen is being raised.
ILLUSTRATIVE EMBODIMENT OF THE INVENTION In the drawings:
FIG. 1 is a front elevational view of the novel toggle press of the invention, in closed position;
FIG. 2 is a side elevational view of the toggle press, in closed position;
FIG. 3 is a view similar to FIG. 1, showing the press in open position;
FIG. 4 is a schematic diagram of the toggle-type mechanism used with the apparatus of the invention showing said mechanism in both open and shut positions and providing some specific detail with respect to angles joining the various lever arms;
FIG. 5 is a partial perspective view of the apparatus shown in FIGS. 1 and 2 but showing placement of the power-stroke cylinders thereon;
FIGS. 6 and 7 are schematic diagrams illustrating the mode of operation of the power-stroke cylinders.
Referring first to FIGS. 1, 2 and 3, it is seen that toggle press apparatus 12 is mounted on crossbar 14 and support plate 15 of frame structure 16. Also mounted on crossbars 14 is a hydraulic power cylinder 18 for actuating ram 20. Support arms 22 and 23 are mounted on support plate 15 and each said arm comprises a fixed pivot pin 24 providing means for positioning two toggle assemblies 26, one on each side of each fixed pivot pin 24.
Each of the four toggle lever assemblies 26 comprises a toggle lever 28 attached by fixed pivot pin 24 to fixed support arms 22 or 23. Pivotally attached to each toggle lever 28 at the outwardly extremity thereof is an upper platen lever arm 30; pivotally attached to the inner extremity of toggle levers 28, and to each other, are ram lever 32 and lower platen lever 34. Ram lever 32 is pivotally attached to a head 36 fixed on ram thereby forming means whereby vertical movement of ram 20 can determine the position of each of levers 32, 34, 28 and 30.
It will be seen that toggle lever assembly, or mechanical linkage means 26 is thus achieved in which the balance lever 28, centrally pivoted at 24, causes the weight of the upper platen 52 (through link, or lever, to substantially counterbalance the weight of the lower platen 44 (through link, or lever, 34) and causes the platens to move toward and away from each other along substantially co-extensive vertical paths.
The power actuated ram mechanism 35, is operably connected by toggle lever 32 and head 36 to the linkage means 26 at pivot 40, which is a cross pin, or rod, of round cross section as are the other pivot pins of the press.
The pivotal connections between head 36 and ram lever 32 is achieved by means of a pivot pin 38 which serves two sets of toggle assemblies 26 as shown in FIGS. 1 and 2 and one directly behind each of them but not visible in the drawing. Similarly another pivot pin 40 forms means to pivotally connect levers 28, 32 and 34. Pivot pin 40 also serves two sets of toggle assemblies 26. Still other pivot pins 42 and 41 form the pivotal connection by which lever 28 is pivotally connected to lower platen carrier assembly 44, and on which lever 30 is pivotally connected to upper platen carrier assembly 52, respectively.
Mounted on each side of lower platen carrier assembly 44 is a positioning member 46. Similarly a positioning member is mounted on each side of upper platen carrier assembly 52. Guide pins 54 are common to and protrude through each pair of members 50 and 46.
Referring to FIGS. 5, 6 and 7, it is seen that pivot pin 43 is mounted in a vertically-elongated hole 56 which has been cut into lever arms 30. A piston rod 58 forms means for applying pressure to the top of pin 43.
Piston rod 58 is actuated by auxiliary, power-actuated ram mechanism including a so-called pancake cylinder 60, which itself is actuated by a hydraulic power means 62. There is one such cylinder 60 at each end of each pivot pin 43, i.e. at each of the four upper corners of the apparatus being described. These pancake cylinders 60 comprise compression means whereby the power stroke required for molding operations can be accomplished independently of the gross positioning stroke whereby the platens are brought together just short of the point that the power stroke must start.
Referring to FIG. 6, it is seen that piston rod 58 is curved to fit pivot pin 43 and that the pivot pin is positioned toward the top of elongated hole 56 at the time the toggle linkages have place the upper and lower platen assemblies in closed position, i.e. their position just prior to initiation of the power stroke. At this point, pancake cylinders 60 are actuated, and pivot pin 43 is pressed by hydraulic means 62, acting through cylinders 60, to the bottom of elongated hole 56. This pressure is transmitted through pins 43 to the platen assembly 52, thus closing the molds on the pressure stroke. There is no significant pressure on the toggle linkage during this pressure stroke actuated by cylinders 60.
When the platens have been closed, pins 43 are in the lower portion of hole 56 as shown in FIG. 7. Removal of pressure exerted on piston rod 58 allows the pins 43 to return to their normal, or no-pressure, position at the top of hole 56.
Thus the pancake cylinders 60 are only actuated by hydraulic pressure after the toggle linkages have been used to place the platens in a position of rest appropriate for starting the power-stroke. This pressure on cylinders can be released as soon as the power-stroke has accomplished its molding mission.
What is claimed is:
1. A toggle-actuated press apparatus of the type described, comprising a framework with a single actuating ram, a vertically-movable upper platen assembly, a vertically-movable lower platen assembly, and a plurality of toggle assemblies mounted thereon,
each said toggle assembly comprising a plurality of levers forming the sole means for supporting said upper and lower platen assemblies on said framework, said toggle assembly counter balancing one said platen with the other and forming means for moderating gross movements of said upper and lower platen assemblies and auxiliary power means, independent of said ram, to provide a relatively short power stroke to at least one said platen assembly.
2. An apparatus as defined in claim 1 wherein said auxiliary means to provide a short power stroke comprises a plurality of short-stroke cylinders and a plurality of pistons, each operable by one of said short-stroke cylinders forming means to provide a relatively short power stroke to at least one said platen assembly.
3. An appartaus as defined in claim 2 wherein each said piston is mounted proximate one said toggle assembly and forms means to apply force to a pivot pin attached to both one said lever and a platen assembly, thereby achieving movement of said platen assembly.
4. An apparatus as defined in claim 2 wherein said shortstroke cylinders are each mounted on the end of a lever which is attached to said upper platen assembly and said pistons are each mounted within said lever and operably positioned therein, each to bear against a pivot pin attached to one of said upper platen assembly and said lever.
5. A toggle-actuated press apparatus of the type described, comprising an actuating ram, a vertically movable lower platen assembly, a vertically movable upper platen assembly, a framework, a plurality of toggle assemblies mounted thereon, each said toggle assembly comprising a plurality of levers, counter-balancing one said platen with the other, a first of which levers is pivotally connected for response to vertical movement of said ram,
a second lever pivotally attached proximate one end thereof to said first lever and to the vertically movable lower platen assembly at the other end thereof,
a third lever pivotally attached to each of said first lever and second lever at one end thereof and pivotally attached to a fourth lever at the other end thereof.
said fourth lever pivotally attached to the vertically movable upper platen assembly at an end of said lever remote from the end at which said third lever is pivotally attached thereto,
a fixed pivot point on said third lever between its points of pivotal attachments to (a) said first and second levers, and (b) said fourth lever,
said toggle assemblies being the sole means for supporting said upper and lower assemblies on said framework, and responsive to the movement of said ram to moderate the gross vertical movement of said platen assemblies.
6. Apparatus as defined in claim 5 comprising auxiliary means independent of said actuating ram to provide a relatively short power stroke to at least one said platen assembly.
7. In a press having an upper and lower platen movable toward and away from each other, the combination of:
mechanical linkage means pivotally supporting said platens for such movement and counterbalancing the weight of one said platen with the other relative to a fixed pivot axis on said press,
and a single power actuated ram mechanism, operably connected by toggle levers, to said mechanical linkage means to move both of said platens simultaneously toward and away from each other.
8. A press as specified in claim 7, wherein said upper platen is supported on said mechanical linkage means for limited vertical movement relative thereto, and
auxiliary power actuated ram mechanism, independent of said first named ram mechanism and mounted on said linkage means, for finally pressing said platens come to rest.
' 6 References Cited UNITED STATES PATENTS 2,624,915 1/1953 Corson 18-30 LT X 3,278,989 10/1966 Neubauer et al 1816 T 3,340,574 9/1967 OBrien et a1 18l6 T J. HOWARD FLINT, JR., Primary Examiner US. Cl. X.R. 30 LT; 25-98