US2431943A - Press mechanism - Google Patents

Description

Dec. 2, 1947. a H. LAND arm. 2,431,943

PRESS IECHANISI mm: Aug. 12, 1943 2 Sheets-Sheet 1 Patented Dec. 2, 1947 mass MECHANISM Edwin H. Land, Cambridge, John R. Swanton, Jr., Newton, and Joseph W. Gibson, Allston, Mass., assignors to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware Application August 12, 1943, Serial No. 498,426

This invention relates to press mechanisms.

It is one object of the invention to provide a novel apparatus whereby assemblies, as for example, of material to. be surfaced and the surfacing members therefor, may be subjected to pressure and heat.

Another object is to provide a novel' pressmechanlsm whereby a uniform pressure may be applied to a material being treated thereby, and wherein there is embodied a novel pressure-transmitting member.

A further object is the provision of novel means for operatively mounting a plurality of pressureapplying platens.

The above and other objects and novel features of this invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for purposes of illustration only and are not intended as a definition of the limits of the invention, reference being primarily had for this latter purpose to the appended 8 Claims. (Cl. 100-71) Fig. 4 is a vertical sectional view, with parts broken away, of one form of apparatus embodying the present invention;

Fig. 5 is an enlarged exaggerated fragmentary sectional view taken substantially along line 5-5 of Fig. 4; and

Fig. 6 is a sectional view taken substantially along line 86 of Fig. 4.

One form of the invention is illustrated by way of example in connection with the surfacing of a rectangular, three-ply blank In (Fig. 1) of the type from which an eyepiece element for a pair of goggles may be formed. The central lamination l0a of said blank is a suitable light-absorbing element, such as a color filter or a polarizing sheet, and the outer laminations I0b are plastic sheets, such as cellulose acetate, which are adhesively or otherwise secured to said light-absorbing element. The thicknesses of the several laminations comprising blank l0 have been exaggerated for purpose of clarity in Fig. 1 and in one commercial form thereof aggregate only slightly over .030".

A suitable surfacing medium for cellulose acetate is methyl methacrylate and a satisfactory surface smoothness is imparted to blank i0 when coated with said medium by bringing into contact therewith a surface-defining plate or member of glass. Good results are obtained with surfacedefining plates I2 (Fig. 2) which are formed of a commercial grade of plate glass approximately thick.

It is to be understood, however, that the novel method and apparatus of the present invention are not limited to the above materials nor are the thicknesses of the materials being surfaced or of the surfacing member critical. Any member may be surfaced in accordance with the invention, provided the surface material thereof has an aflinity for thesurfacing medium. Moreover, the surfacing medium may consist of any moldable material that can be solidified from a fluid or viscous state while in contact with the face material of the element being surfaced, and which can have a given surface smoothness imparted thereto during solidification by a surface-defining member, such as a glass plate. y

In accordance with the preferred method for carrying out the invention, elements I 0 are sandwichedbetween three surfacing plates l 2 (Fig. 2),

each face of said elements being coated with a thin, uniform layer of methyl methacrylate monomer. To provide layers of methyl methacrylate of the desired uniformity and thickness over the faces ofelements l0, the several parts of the five-ply arrangement i0, i2 are assembled in a novel manner. One of the surfacing plates I2 is first held, for example, in a suitable support N (Fig. 3) at an angle to the vertical and with the lower edge thereof extending horizontally. An element i0 is then positioned in said support with its lower edge in contact with the lower edge of said plate so as to form an acute dihedral angle with the latter, and the monomeric methyl methacrylate in a suitable condition for polymerization is then introduced, as for example, by being squirted from a syringe l8, between the-adjacent faces of said plate and element. Thereafter element l 0 is pivoted about its lower edge into contact with plate i2, causing, the surfacing medium to spread uniformly and thinly over the entire surface of said element. This step is repeated with each of the successive laminations which constitute sandwich l0, l2, the previously assembled 'erably a unitary structure.

components in each instance serving as the base. i. e., in the same capacity as the first plate l2. and the newly added components being pivoted into position-in the same manner as the first element I0, methyl methacrylate being introduced between each pair of adjoining surfaces. v

In order to facilitate removal of plates l2 from elements l8 after the latter are surfaced, it is 4 are preferably of the same construction and similarly mounted as diaphragm 42 by elements 58 and constitute the end walls of a fluid-tight chamber whose side walls are formed by said frame. The chamber is preferably filled with fluid 48, and

v has mounted therein awinding tube 68 which is supported by, and extends through, frame 56. In order to mount platen 34"for movement in preferable to have diagonally opposite corners of said plates clipped and bevelled as at [1. 7

To surface elements l8, pressure is preferably applied to the outer laminations of sandwich l8,

l2 to press the surface-defining elements into close contact with the surfacing medium and. while under this pressure, the surfacing medium is polymerized until hardened, preferably by the application of heat. In order to expediently and effectively accomplish this, novelmeans are prothreaded at 28 so as to be rigidly secured to said supports by nuts 38.

To simultaneously apply a uniform and substantially equal pressure to the opposite surfaces of each of a pair of sandwiches l8, l2, press members 32, 34, and '36 are provided and are operatively mounted between supports 28 and 22. In

the form illustrated (Fig. 4), the upper press member or platen 32 comprises a metallic cupshaped member, as for example a rectangular frame 38 and a plate 39 integrally formed with,

or secured to, said frame, said frame and said plate constituting the side and top walls respectively of a fluid-tight chamber. Forming the lower or pressure-applying wall of said chamber is a flexible diaphragm 42, comprising, for example, an inner layer 42a of neoprene and an outer layer of fine mesh screen or wire cloth 42b (Fig. 5), said diaphragm having the edges thereof pressed into fluid-tight engagement with the lower face of frame 38, preferably by means of a rectangular frame element 44, which is secured to said frame as by screws 46. Element 44 may consist of four separate metallic strips but is pref- Platen 32 is rigidly secured to a block 48, for example of wood, and the latter is, in turn, fixed to the lower face of support 28 and serves to insulate said support from member 38, 39. The interior of the chamber thus formed by diaphragm 42, frame 38, and plate 39, is filled with a suitable fluid medium 48, as for example, oil, glycerine, or ethylene glycol. Of these oil is preferred, although any readily available fluid which will not boil at the temperature maintained during surfacing may be used. To accelerate the polymerization of the surfacing medium, suitable heating means are contained'within frame 38 and may comprise a winding tube 58 which is supported by said frame I and which has a suitable heating medium circulated therethrough to maintain platen 32 at a desired temperature.

Siidably mounted below platen 32 in substantial alignment therewith is platen 34 which comprises i a pair of substantially parallel pressure-applying elements, such as diaphragms 52 and 54, mounted across the upper and lower faces, respectively, of

a rectangularframe 56. Diaphragms 52 and 54 a direction perpendicular to the substantially parallel pressure-applying diaphragms 42, 52, and 54, frame 58 is preferably provided with brackets 62 (Figs. 4 and 6) adjacent rods 24, said brackets being secured to or integrally formed with said frame and'c'arrylng bearings 64 which slidably engage rods24, Each-of said bearings may be mounted for limited lateral adjustment relative to its bracket, and in the form illustrated, each is provided with a slot into which the supporting bracket associated therewith is press fitted and is held in operative position by a set screw 66. Eachcf bearings 84 preferably subtends lessthan 180 of the cylindrical peripheral surface of the rod.24 which it engages.

To predeterminethe lowermost position, i. e., the disengaged. central position, of platen 34, and to serve as further guides for said platen during the movement thereof into operative position, a plurality ,of guide rods 68 (Fig. 4) may be provided. As shown, apair of 'said rods are operatively mounted on each of brackets 62 (Fig. 6), being threadably or otherwise rigidly secured thereto at their lower endsso as to extend vertically upward therefrom. At their upper ends said rods are slidably mounted in recesses provided therefor in support 28, and to limit the downward movement thereof, each of said rods has a nut 10, or other axially adjustable member secured to the upper end thereof. Suitable resilient means, such as coil springs'lZ may be provided to normally bias platen 34 downward into inoperative osition and in the illustrated embodiment said springs are mounted around rods 68 so as to have their lower ends bearing against plat-en 34 and their upper ends bearing against the lower surface of support 20. I

Platen 36 is slidably mounted below and directly opposite platen 34 and comprises an upper pressure-transmitting member, suGlras adiaphragm 14, which is preferably of the same construction and similarly mounted as diaphragm 42 on a frame 16 by means of an element 18. Integrally formed with said frame or mounted thereon in fluid-tight engagement therewith is a bottom plate 80 and the chamber thus formed within said frame is filled with fluid 48 and contains heating means in the form of a winding tube 82 for circulating a suitable heating medium through platen 36. The latter is secured to a platform 84, for example by an insulating member such as a wooden block 88, and said platform is provided with bearings 88 which are in sliding engagement with rods 24 to mount the entire platen assembly for vertical movement. Bearings 88 are rigidly secured to platform 84 in any suitable manner and it is preferable to provide means for laterally adjusting at least one of said bearings relative to said platform. For example, the left bearing ashown in Fig. 4, may be mounted on an element 98 which has a siot'92 provided therein and is normally held fixed'relative to platform 84 by screws 84 extending through said slot. The lateral position of said element may thus be readily adjusted to predetermine the lateral separation of bearings 88, the latter being constructed to engage less than 180 of the peripheral surface of rods 24.

To predetermine the lowermost position of platen 36 and provide means for actuating said platen and platen 34 to effect the pressure appli cation to sandwiches I II, I 2, suitable means, as for example a cylinder 96 and a piston 98 reciprocally mounted therein, are provided, said cylinder in the form illustrated being centrally located below platform 84 and being secured at its lower end as by bolts I00 to support 22. Suitable sealing means are provided for rendering oil tight the pressure chamber formed in said cylinder by said piston, and in the form shown, said means comprise a conventional hydraulic oil cup 91 held in operative engagement with the lower end of said plunger as by a spring 99. The latter also serves to maintain said plunger at all times above a fluid inlet port I06 rovided adjacent the lower end of cylinder 96. In the inoperative or disengaged position of platen 36, platform 84 rests on theupper end of said cylinder, being normally urged into said inoperative position by suitable resilient means, such as coil springs I02, which are under tension and are secured at their lower ends to support 22 and at their upper ends to said platform as by eyes I04. To move platen 36 into operative pos tion, means are adapted to admit a suitable fluid, such as oil, under pressure into port I06 whereby the piston is moved upward to raise platen 36. It is to be understood that the lowermost position of platen 36 may be predetermined. for example by means, such as collars, (not shown) fixedly mounted on rods 24 whereby said platen is normally held above the upper edge of said cylinder.

In operation, a surfacing assembly I 0, I2 is disposed on both of platens 36 and 34 while the latter are held in their lowermost or inoperative position. Each of tubes 50, 60, and 82 has a suitable heating medium, such as water, at a pressure in excess of the steam saturation pressure for its temperature, continuously circulated therethrough. Flud is admitted into cylinder 96 to raise platen 36 until the assembly mounted thereon engages and raises platen 34 to cause the latter or the assembly mounted thereon to be pressed into engagement with platen 32. Assemblies Ill, I2 are pressed between diaphragms I4 and 54, and diaphragrns 52 and 42 which, because of their flexibility, apply uniformly the uniform pressure transmitted thereto by the fluid content 48 of each of said platens. When the pressure is relieved at the completion of the polymerization of the surfacing agent, springs I2 and I02 act to move platens 34 and 36, respectively, into inoperative position against the fluid and mechanical frictional resistance and the assemblies I0, I2 are removed. Thereafter said assemblies are cooled and plates I2 are separated from the surfaced blanks III and used again as surfacing members.

By controlling the pressure of the fluid admitted into cylinder 96, any predetermined pressure may be applied to assemblies III, I2 and the temperature of the fluid in tubes 50,60 and 82 can also'be controlled to provide a desired temperature at the surfaces of said assemblies. The time required to satisfactorily effect a given surfacing depends on the time the surfacing agent has been permitted to soak into the surface of the member being surfaced after it is applied thereto and before it is inserted into the press mechanism, on the temperature at which the assembly is maintained during the soaking, on the pressure applied by platens 32, 34, and 36 of the press mechasure application, and on the amount of polymerization catalyst mixed with the surfacing agent.

When methyl methacrylate monomer containing 3% of a suitable catalyst, such as benzoyl peroxide. is employed as the surfacing medium, it has been found satisfactory to circulate water at a temperature of approximately 250 to 350 F. through'tubes 50, 60, and 82. and to apply a sufficient fluid pressure to the platens to have the latterexert a uniform pressure of approximately 5 to 50 lbs. per square inch on the opposite surfaces of assemblies I 0, I2.

There is thus provided novel apparatus whereby a material, such as a transparent, resinous sheet, having an aflinity for a plastic medium, may be surfaced by having a surface layer of said medium polymerized thereon while a suitable surface-defining member is maintained in contact with said medium, said apparatus comprising novel press means for bringing and holding said material and said member in contact.

It will now be apparent to those skilled in the art that the novel pressure-applying means may be used for other purposes than in connection with the surfacing of sheet materials. It is to be understood also that other heating means, such as electrical coils, may be embodied in the platens for heating the latter.

Since certain changes in the constructions set forth which embody the invention and in the steps for carrying out the process of the invention may invention, it is intended that all matter contained in the above description or shown in the accom panyin drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

What is claimed is:

1. In apparatus of the character described, a press mechanism comprising, in combination, at least three fluid-tight platens filled with an incompressible fluid, adjacent walls of adjacent platens being deformable and in engagement with the fluid filling said platens, means fixing one of said platens against movement, means for mounting the other platens for movement relative to said fixed platen, means for rendering adjacent platens operative to apply a pressure to material disposed between said adjacent walls, said lastnamed means comprising a member adapted to engage one of said movable platens and cause the movement of said movable platens in the direction of said fixed platen and a mechanism for applying fluid pressure to said member to actuate the latter, and means for biasing said movable platens in a direction opposing movement thereof into operative position, said biasing means causing said platens to assume a predeterminedinoperative position wherein said platens are suf- 7 one of the two outermost of said platens against movement, means for mounting the other of said platens for movement relative to said fixed platen, means for rendering adjacent platens operative to apply a pressure to material disposed between said adjacent walls, said last-named means comprising a member adapted to engage the other outermost platen and to engage and move said platen and a mechanism for actuating said member, means for biasing said movable platens in a direction opposing movement thereof into operative position, said last-named biasing means causing said platens to assume a predetermined inoperative position wherein said platens are sufficiently spaced apart to permit removal and insertion therebetween of the material to be processed thereby, and means for circulating a heating medium through each of said platens.

3. In apparatus of the class described, three vertically spaced platens, each said platen comprising a frame member formed of a rigid, nondeformable material and at least one wall of a deformable material, adjacent walls of adjacent platens being deformable, means for holding the upper platen stationary, means for mounting the central platen for vertical movement, means for normally biasing said central platen away from said upper platen, means for mounting the lower platen for vertical movement, means for normally biasing said lower platen away from said central platen, and means for moving said lower platen in the direction of said upper platen to render all of said platens operative to compress material disposed therebetween, said biasing means being operative to cause said platens to assume, when said means for moving said lower platen is inoperative, a predetermined inoperative position wherein said platens are sufiiciently spaced apart for removal and insertion therebetween of the material to be processed thereby.

4. In apparatus of the character described, three vertically spaced platens, each said platen comprising a frame member formed of a rigid, nondeformable material and at least one wall of a deformable material, adjacent walls of adjacent platens being deformable, means for fixing the upper platen against movement, means for mounting the central platen for vertical movement, means for normally biasing said central platen away from said upper platen, means for predetermining the normal separation between said upper and central platens, means for mounting the lower platen for vertical movement, means for normally biasing said lower platen away from said central platen, means for predetermining the normal separation between said central and lower platens, and actuating means for moving said lower platen in the direction of said upper platen to render all of said platens operative to compress material disposed therebetween, said biasing means being operative, whenever said actuating means is inoperative, to cause said platens to assume a predetermined inoperative position wherein said platens are suflieiently spaced apart for removal and insertion therebetween of the material to be processed thereby.

5. In a press mechanism, at least three substantially parallel platens, the uppermost platen being stationary and the other platens being movable relative thereto in a direction substantially perpendicular thereto, each said platen comprising a frame member of a rigid, nondeformable material, at least one wall of adeformable material mounted on said frame member, an incompressible fluid contained therein and in contact with the deformable wall thereof and conduits mounted in said frame member for circulating a heating medium through said platen, adjacent walls of adjacent platens being deformable, means for applying pressure to the lowermost platen whereby all of said platens are rendered operative, means for predetermining the separation of said platens in inoperative position, and resilient means normally biasing said platens into inoperative position, said resilient means causing said platens to be sufficiently spaced apart when inoperative to permit of the ready removal and insertion therebetween of the material to be processed thereby.

6. In apparatus of the character described, a press mechanism comprising, in combination, at least three fluid-tight platens filled with an incompressible fluid, adjacent walls of adjacent platens being deformable and in engagement with the fluid filling said platens, means for fixing one of said platens against movement and means for mounting the others of said platens for movement with respect to said fixed platen, means for rendering adjacent platens cperative to apply pressure to material disposed between said adjacent walls, said last-named means comprising a member adapted to engage one of said movable platens and cause movement of said movable platens and a mechanism for actuating said member, and spring means for biasing said movable platens in a direction opposing movement thereof into operative position, said spring means causing said platens to be sufiiciently spaced apart when inoperative to permit of the ready removal and insertion therebetween of the material to be processed thereby.

7. In a press mechanism, at least three substantially parallel platens, the upper-most platen being stationary and the other platens being movable relatively thereto in a direction substantially perpendicular thereto, each said platen comprising a frame member of a rigid, nondeformable material, at least one wall of a deformable material mounted on said frame member, an incompressible fluid contained therein and in contact with the deformable wall thereof and conduits mounted in said frame member for circulating a heating medium through said platen, adjacent walls of adjacent platens being deformable, means for applying pressure to the lowermost platen whereby all of said platens are rendered operative, means for predetermining the separation of said platens in inoperative position, and spring means normally biasing said platens into inoperative position, said spring means being operative, whenever said actuating means is inoperative, to cause said platens to assume a predetermined inoperative position wherein said platens are sufficiently spaced apart for removal and insertion therebetween of the material to be processed thereby.

8. In a press mechanism, three substantially parallel platens, the upper-most platen beingstationary and the other platens being movable relatively thereto in a direction substantially perpendicular thereto, each said platen comprising a frame member of a rigid, nondeformable material, at least one wall of a deformable material mounted on said frame member, an incompressible fluid contained therein and in contact with the deformable wall thereof and conduits mounted in said frame member for circulating a heating medium through said platen, adjacent walls of adjacent platens being deformable, means for applying pressure to the lowermost platen whereby all of said platens are rendered operative, stop members for predetermining the separation of said movable platens in inoperative position, com- EDWIN H. LAND. JOHN R. SWANTON, JR. J. W. GIBSON.

REFERENCES CITED The following references are of record in the file of this patent: 1

Number 10 UNITED STATES PATENTS Name Date Hyatt July 3, 1883 Spaulding Apr. 8, 1902 Gammeter Nov. 25, 1924 Roberts May 12, 1925 McCarthy May 29, 1928 Fox et a] Apr. 15, 1930 Owen May 26, 1931 Lytle Feb. 9, 1932 Lacy Aug. 9, 1932 Drake Aug. 23, 1932 Mead Mar. 7, 1933 Merenda Oct, 31, 1933 Williams Mar. 13, 1934 Willshaw et a1 May 7, 1935 'Shutt Oct. 6, 1936 Waters Mar. 1, 1938 Lauterbach Apr. 18, 1939 Stacy -1 Oct. 19, 1934

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