US2558796A - Degassing apparatus for platen presses - Google Patents

Description

Patented July 3, 1951 DEGASSING APPARATUS FOR PLATEN- PRESSES Thomas-P. Tapper; Prospect Park, Pa., assignor to Baldwin-Lima-Hamilton Corporation', a corpo'- ration of` Pennsylvania Application April 9, 1948,.Serial No. 20,063

After material to be compressed and heat-treated has been placed between the spaced platens and centered' thereon, the press is closed by an upwardly moving hydraulically operated ram of the press. After applying low hydraulic pressure to the material for a few seconds gases form, as is well-known, and become trapped between the material and the platens immediately above and below the material. These gases must be allowed to'escape before high' hydraulic pressure is applied' in order to prevent' distortion or rupture of the material. The usual but not' always entirely satisfactory practice heretofore used is merely to decrease the press pressure on the platens to the exact point that will counterbalance the moving weights, i. e., the movable platens and material, but will not permit the topmost movable platen to* drop away from the stationary platen ah'xed to the crosshead. This relaxation of the pressure which is known as the breathing or d'egassing operation permits the gases to escape despite the dead weight of the plat'ens on the material. The importance of attaining a precise degree of control of the hydraulic pressure on the pla'tens, which is extremely difficult in the Conventional platen press, lies in the fact that', in the case of some materials, such* as, for instance, that required in the making of'plywood, should such hydraulic pressure be decreased too much and' the uppermost movable platen be allowed to f'all'away" from the fixed platen, even' to a small extent, to

leave a space between the material and the fixed' platen, the trapped gases between said'material L and the topmost movable platen would' beable to raise the'material' and slide it out of' its centered position on the movable platen. such diffi'culty is of course' experienced only in the case of the' material between these* two uppermost platens,

the material on each of the other movable platens platens can, of course, and must be recentered on the topmost movable platen, in so doing there is a considerab'le loss of' time and e'ort'.

Anpobject of my inventionisto provide simple,`

positive and effective means whereby material centered on` the uppermost movabl platen of a of the type described which consists essentially;`

2 platen press of the type described will befpre.- vented from being displaced by trappedi gases; during the breathing or degassing operation Another object is to provide such means whereby it will be possible to eliminate anyneedor precise control of hydraulic pressurev onthe platens for the breathing or degassing operation.

Other objects and advantages will be more ap-= parent to those skilled in the art from the following description of the accompanying drawingsin which:

Fig. 1 is a front elevation of a' platen pressof\ the type described. in open or loading position, to., whichmy device is shown applied;

Fig. 2 is an enlarged detailed view, partly ini section, showing th operation of my device whenl the press is in pressing position; and

Fig, 3 is a View similar to Fig. 2, showing theoperation of the device when the press is, in'` breathng or degassing position..

In the particular embodiment of' the invention.

which is disclosed herein merely for the purposes of illustrating one specific form among possible: others that the invention might take in practice, I show diagrammatically in Fig. 1 a platen press:

of a hydraulic cylinder l, a ram 2 having recipro-` catlng movement within the cylinder, a moving platen 3 afilxed to the ram, an upper stationary: crosshead 4 supported in the usual and wellknown manner by four vertical tension columns 5. whose lower ends are rigidly aflixed to the oylinder, and a plurality of vertically movable hot plates or platens 8 between which sheets of mathrough progressively shorter lugs lil of the platen;

guides engaging progressively. longer steps !Dal of stephangers 9. Secured to crosshead l is a usual heat .insulating plate ll. I-Iowever, instead of employing a platen that is immovably aiiixed to crosshead 4, as in the case of Conventional platen presses, I use instead a fioating platen l2- positioned between and in vertical alignment with in-- sulating plate ll and the uppermost of movable platens 6, and adapted and arranged to have vertical movement as in the case of the movable platens and thereby be able to utilize the' weight of the uppermost platen for degassing purposes. While any of several simple ways may be em*- ployed to mountfioating platen [2 so as to allow it also to be raised and lowered by the moving ram;

Lprefer, for the sake of- Simplicity and inexper-- siveness of construction, tosuspendthisfioating 'fioating platen l2 through lugs M.

'of the materia-1 begins.

platen by a number' of vertically disposed rods, each having an enlarged end, such as, for example, inverted stud bolts !3, screwed into or otherwise Secured to, and rigidly pendent from, the underside of crosshead 4. These stud bolts pass freely through vertically drilled holes in extended portions'of edges of the fioating platen, such as, for instance, lugs M secured to or integrally formed with at least two sides of floating platen !2 so that' the floating platen may be moved upwardly by the pressure of the moving ram and downwardly by gravity. When the press is in open or loading position, as shown in Fig. 1, the heads of stud bolts !3 carry the weight of The shanks of bolts l3 are of such length that, with the press in open position, there may b a small space [5 between insulating plate ll and fioating platen !2. Platen guides 8 and platen supporting means 9, incident to each of movable platens 6, may of course be dispensed with in the case of the uppermost or fioating platen l2, as the shanks of stud bolts l3 maintain said platen in vertical alignment with movable platens 6.

In the operation of my device, after material has been centered on the platens, the press is closed by the introduction of low hydraulic pressure into cylinder l, in usual manner. such pressure causes ram 2 and moving platen 3 to be moved upwardly. Moving platen 3 then sucsessively raises movable platens 6 off their respective supports lila, commencing with the lowermost platen until all movable platens 6 have been so collected on moving platen 3 and the material centered on each movable platen 6 is in engagement with the underside of the platen immediately above it. In the case of the uppermost movable platen '6, the material centered thereon engages the underside of fioating platen |2 and lifts the platen so that its weight is thereby transferred from the heads of stud bolts [3 to theupwardly moving pile of platens. Space |5 is eliminated when the upperside of fioating platen l2 comes into contact with insulating plate ll, as shown in Fig. 2, when hydraulic compression Such pressure is at this time of a low Value for after only a few seconds of heat .and pressure to the material the gases which have begun to form must be allowed to escape before any further compression is applied. 'I'o free these gases from between the material and the platens above and below the material, such hydraulic pressure on the platens and material is slightly decreased, allowing movable platens e and fioating platen !2 to move downwardly by gravity and causing space !5 between insulating plate H and the material on the uppermost platen of movable platens 6 to reappear, as shown in Fig. 3. While the platens may be so lowered to any point before drilled lugs [4 come into contact with the heads of guide bolts !3, the platens are as a praotical matter lower'ed a distance sufiicient only to free all the platens and materials of such hydraulic pressure. It will be seen that at no time throughout this breathing or degassing operation has any of the material l been relieved of the pressure of floating platen 52, as it would have been had said platen been immovably affxed to crosshead 4 as heretofore. The result is that the material between floating platen :2 and the uppermost of on the material. The material of course remains" so centered while the press is again closed and the requisite amount of high hydraulc pressure is applied to the platens and to the material in the usual manner. It is also seen that the need for attaining precise control of hydraulic pressure on the platens during this degassing operation, which is imperative in the usual platen press, has been eliminated as a result of the device described herein.

From the disclosure herein, it is seen that I have provided a simple and effcient, though inexpensive, means of eliminating in a platen press the displacement of material between the two uppermost platens during the breathing or degassing operation.

It will of course be understood by those skilled in the art that various changes may be made in the construction and arrangement of parts without departing from the spirit of the invention as set forth in the appended claims.

I claim:

1. In a platen press of the type having a cylinder, a ram therein, a stationary crosshead, a plurality of vertically movable platens positioned between the ram and crosshead, and means :for supporting said movable platens in spaced relation to each other when the press is in fuily open position but adapted to allow the weight of such platens to remain on material between said platens when the press is partialiy open during a degassing operation comprising, in combination, a vertically floating platen disposed immediately below said crosshead and above the uppermost one of said movable platens, said heating platen being supported upwardly against the crosshead solely by the ram force so as tobe freely separable from said crosshead and openly spaced therefrom when the press is open whereby said fioating platen may follow down the other platens during said partial degassing opening of the press and thereby allow the weight oi said oating platen to be maintained on the material between the fioating platen and the uppermost one of said movable platens, and means or supporting the weight of the fioating platen so that when the press is fully opened material may be removed from or inserted between the platens.

2. The combination set orth in claim 1 further characterized in 'that the means for supporting the weight of the loating platen when the press is in fully open positio-n consists of vertical rods dependently supported by the crosshead and having enlarged ends on which the weight' of the fioating platen rests when the press is open.

3. The combination set forth in claim 2 further characterized in that the vertical rods have shanks of such length as to allow the weight of the fioating platen to remain on the movable platens during the degassing operation and to be transferred to the enlarged encls of the vertical rods only when the press is opened a disstance greate' than that required for the degassing operation.

THOMAS P. TAPhER.

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

UNITED STATES PATENTS Number Name i Date 1,121A70 Bushnell Dec. 15, 1914 2,217,652 e Quick Oct.481940

Images