US2884032A - Multi-platen hot press - Google Patents

Description

emf-irri- April 2s, 1959 Filed April 15, 1957 F. THURNHER MULTI-PLATEN HOT PRESS 3 Sheets-Sheet. 1

INVENTOR.

Ferdinand Thurnher Afiorneys.

Filed April 15,' 1957 April 1959 F. THURNHER 2,884,032

MULTI-FLATEN HOT PRESS 3 Sheets-Sheet 2 W1 ii- INVENTOR.

' Ferdinand Thurnher Attorneys April 28, 1959 Filed April 15, 1957 3 3 61 I EH-:2;

F. 'THVIDJRNHER MULTI-PLATEN HOT PRESS s SheetsQSheet 3 INVENTOR. Fe rdinond Thurnher Attorneys MULTI-PLATEN HOT PRESS Ferdinand Thurnher, Seattle, Wash., assignor to Washington Iron Works, Seattle, Wash., a corporation of Washington Application April 15, 1957, Serial No. 652,973

6 Claims. (Cl. 144-281) This invention relates to a hot press, and particularly a multi-platen hot press of the type used in the manufacture of sundry board products such, for example, as hardboard, plywood and the like.

In hot presses of the character to which the present invention pertains, the multiple platens are mounted one above another between a stationary top plate and a vertically movable bottom plate, hydraulic pressure being applied to said lower plate to elevate the same and responsively close the press pockets which are defined between the several platens. When hot presses of the nature described were first introduced the proper positioning of the platens in the open condition of the press was accomplished by having the platens rest on respective shelves. These shelves were offset one from another so that the supporting shelf of each upper platen occupied an out-of-the-way position with all of the platens therebelow to give clearance for the lower platens as the press closed. The closing action was a progressive operation with each successive platen, from the bottom up, rising only as the same became sustained by the platen therebelow. One objection to a press of this type is that the material being compressed is subject to a considerably longer period of curing in the lower pockets than in the upper pockets of the press, the added time for the lowermost pocket as compared with that of the uppermost pocket perforce comprising the closing time for a single pocket multiplied by the number of pockets in the press. Also, and particularly with hardboard, in which the mats supplied to the press are composed of material which is relatively unstable until pressed, the output from this type of a press is quite low in that the platens must be held to a speed which will not unduly agitate the air as the latter is dispelled from each pocket in course of closing the same.

In an effort to speed the over-all closing time of the press and at the same time hold each lower platen to a speed only so much above that of the next-higher platen as will not unduly disturb the displaced air, a pantograph linkage has in some instances been applied to the platens. Its disadvantage is that the platens must follow a precise pattern of predetermined motion, making no provision for minor differences in the thickness of the mats, boards or the like which are supplied to the press pockets, or in fact the occasional total absence of a mat or board from a pocket, with the result that platens other than the movable bottom plate are forced to carry the load of a platen or platens thereabove. This load can then be passed to the movable bottom plate only through the pantograph linkage.

Another development aimed at correcting the pantograph faults has the press surmounted by a beam which is pivoted for vertical swinging movement. The several platens are hung from this beam by separate flexible cables trained over pulleys. By another train of pulleys and cables the beam is so connected with the hydraulically powered bottom plate that a rise of such bottom plate raises the beam. This responsively elevates the platens 2,884,032 Patented Apr. 28, 1959 to close the same in concert and yet, by reason of the flexibility of the cables which carry the platens, any one or more of the platens is free to rise independently of the proportioned movement of the whole assembly. One disadvantage of the arrangement is an unduly high cost for rigging the press with a multitude of heavy-duty pulleys, cables and fittings. It is also necessary to give almost constant attention to the press in keeping the cables adjusted for proper length.

It is the general object of the present invention to provide a perfected multi-platen hot press which overcomes the enumerated and other disadvantages inherent to hot presses as they have been heretofore known. With this and other more particular objects and advantages in view, and which Will appear and be understood in the course of the following description and claims, the invention consists in the novel construction and in the adaptation and combination of parts hereinafter described and claimed.

In the accompanying drawings:

Figure 1 is a perspective view illustrating a multiplaten hot press equipped with hanger structure embodying teachings of the present invention.

Fig. 2 is a fragmentary elevation thereof viewed from an end of the press and showing by full and dotted lines the open and closed positions of the hanger structure.

Fig. 3 is a fragmentary elevation viewing said hanger structure from the side of the press.

Fig. 4 is a fragmentary longitudinal vertical sectional view drawn to an enlarged scale on line 4-4 of Fig. 2.

Fig. 5 is a fragmentary longitudinal vertical sectional View on line 5-5 of Fig. 2, using a scale the same as that of Fig. 4; and

Fig. 6 is a View similar to Fig. 4 illustrating a modified hanger arrangement.

Referring to said drawings, the numeral ll? designates the box bedplate, 11 the stationary head-plate supported in elevated relation above said bedplate by laterally spaced rows of columns 12, and 13 the movable baseplate, or cross-head as it will be hereinafter termed, of a conventional multi-platen hot press, said cross-head being carried for vertical movement by a multiplicity of hydraulic rams 14 working in cylinders set into the box bedplate. The press which I have elected to illustrate is one defining twenty openings between a stacked succession of twenty one platens. The uppermost plate 15 is made integral with the head-plate 11 upon the underside thereof. The lowermost platen 16 is made integral with the cross-head 13 upon the upperside thereof. The structure of the present invention gives support to the intervening platens 17 in a manner causing the same to open and close in concert responsive to ascending and desceding motion, respectively, of the movable cross-head. These structures are applied to the two sides of the press adjacent each of the corners, and are identical. A description of one, as illustrated in Figs. 2 and 3, will thus suflice for the others.

Being essentially an assembly of parts producing an elbowed lever mechanism, said structure provides, as the upper arm of the assembly, an outrigger beam as fnted by its inner end to a pivot shaft 21 journaled from the head-plate for oscillatory motion about a longitudinal horizontal axis. The forearm of the assembly comprises a radius bar 22 articulating, as at 24, with the free end of the beam and having its lower end pivoted, as at 23, to a bracket 25 bo-ltably secured to the side face of the cross-head. It is desirable to relieve the bolts of said brackets from the vertical load passed into the crosshead from the radius bar 22, and for this purpose a block or blocks (not shown) is Welded to the cross-read under the lower edge of the bracket.

The outrigger beam is provided within its length with a plurality of in-line openings 26 (Figs. 4 and 6) drilled horizontally from the front to the back face on parallel centers which are spaced equidistantly one from another and from the two terminal pins 21 and 23. These openings 26 correspond in number with the number of the platens 17. As can be seen from an inspection of Fig. 2, the center of the wrist pin 24 is spaced beyond the outermost drill-hole 2d a distance substantially greater than the spacing between said drill-holes. The significance of this arrangement Will be later pointed out in course of describing a swing arc through which the beam moves.

Journaled by bushings 27 in each of said drill-holes is a respective pivot pin 3%, and provided upon an end of each of these pivot pins is an exposed squared head 3-1 provided with a drill-hole 32 extending diametrically of the head from one to another of two opposite flats. In the application of the pivot pins to the beam, each successive pin is oppositely directed so as to have the heads 31 of each alternate pin project from one face while the head 31 of each intervening pin projects from the opposite face. A related one of the multiple platens 17 is hung by a respective rod 33 from each of said pivot pins 30. The rod has its lower end pivotally connected by a pin 34 to a furcate bracket 35 (Figs. 2 and bolted or otherwise secured to the platen, and has its upper end slidably received through the diametrical drill-hole 32 of the pivot pin 3-3, the upper end of the rod being threaded to receive a thrust nut 36 backed by a lock nut 37. As the pivot connection between the rod and the platen-carried bracket there is provided a ball joint (see Fig. 5) in compensation of minor variations in the degree of vertical movement between the four corners of a platen.

In the two embodiments of the invention detailed in Figs. 4 and 6, the one (Fig. 4) hangs the load of the platen directly from the nuts 3637. With this arrangement it becomes important that each successive platen, from the top down, close a fractional moment after the next lower platen so that no one of the platens 17 will be called upon to itself sustain the weight of a platen or platens thereabove. Were the platens to have an absolute simultaneous closing, said referred-to adverse loading situation would obtain excepting in the unlikely case that the thickness of the mats contained in all of the press openings was precisely exact. The direct support by any one of the platens 17, of the weight of one or more of the platens thereabove, perforce subjects the concerned hanger rod 33 to destructive loading, bearing in mind that each set of four rods, one for each corner of the platen, would be then called upon to carry a multiple of 8500 pounds, this being the weight of the individual platens. In order to accomplish said desired end of having an almost indiscernible time lag in the closing of each upper platen relative to the next lower platen, the beam is caused to swing vertically through an arc of travel having its low limit below and its high limit above a horizontal plane traversing the oscillatory axis, and the below-horizontal travel is made substantially greater than the above-horizontal travel. Otherwise stated, the angle through which the beam travels in its movement from the low limit to a horizontal plane traversing the oscillatory axis substantially exceeds the angle travelled as the beam moves from said horizontal plane to its high limit. A setting which i have found to be suitable provides a 50 bottom-arc travel and a 35 top-arc travel. The geometry of the above can be explained by pointing out that while the distance travelled by the bottom ends (the pivots 34) of the hanger rods 33 is computed along a coinciding vertical line, that of the upper ends (the pivots 34)) is computed along lines which are oblique to the vertical. The obliquity of these distance lines becomes progressively greater from the inner toward the outer end of the beam and it thus follows that each pin 30, from the outer toward the inner end, will at any given level travel a greater distance, in proportion to the distance measured along a perpendicular raised from the pin, than the next adjacent pin. Increasing the spacing as between the wrist pin 24 and the outermost drill hole 26, as compared with the uniform spacing between adjacent said drill-holes, further exaggerates this proportional travel and this is advantageous to give greater insurance that the full load of the closing press platens will be borne by the cross-head, initially through the radius bar and then by direct suspension as press pressure is applied to the mats. It should be borne in mind that the overall time lag between the moment when the platen 16 carried by the cross-head 13 first picks up the weight of the lowermost platen 17 and the moment when the uppermost platen 17 acts through its sustained mat to press against the stationary platen 15 consumes only a very minor part of the total press-closing time, in the order, say, of 5%. This is important in order that the press may close with relative rapidity, say 20 seconds, and yet preclude any single pocket of the press from having a closing speed so rapid that the air within the pocket is ex pelled at a velocity which will disturb the fibers, chips or particles, as the case may be, of the mat. It occasionally develops that one of the pockets of a press does not receive a mat in the loading operation thereof. The ability of the present hanger rods to lift without inhibition, in that the head ends slide freely through the drillholes 32 of the pivot pins 30, prevents damage to the press in such an eventuality.

In Fig. 6 I have illustrated a second embodiment in which the hanger rods, here designated by 30, are moderately longer and have fairly stiff compression springs 41 received between the pivot pins 26 and the head nuts 4243, thus floating the platens. This spring suspension perforce prevents any hanger rod from carrying the weight of more than its own platen in that variables as between the press gaps are taken up by the springs. With this embodiment it becomes unnecessary to engineer the described time lag into the lever hook-up, and which is to say that the swing arc of the beam as it moves between top and bottom limits of travel is or may be the same both above and below a horizontal plane traversing the center of the pivot pin. While the first-described simpler embodiment has the advantage of reducing the cost of the equipment, and eliminating a possible although unlikely source of mechanical failure, namely spring breakage, I consider the spring arrangement to be my preferred embodiment.

It is thought that the invention will have been clearly understood from the foregoing detailed description of the illustrated embodiments. Modifications may be resorted to without departing from the spirit of the invention and I accordingly intend that no limitations are to be implied and that the hereto annexed claims be given a scope fully commensurate with the broadest interpretation to which the employed language fairly admits.

What I claim is:

1. in a hot press, in combination with the stationary head at the top, the movable cross-head at the bottom, and the intervening platens, structure applied to each of the four corners of the press comprising an outrigger beam having its inner end pivoted to the head for vertical swinging motion and having a radius bar extending as a pitman form the outer end to the cross-head, and a plurality of hanger rods, one for each of said intervening platens, suspending the platens from the beam with the head ends thereof connecting with the beam at points equidistantly spaced along the length of the beam, said hanger rods each connecting with the related platen by a respective ball-joint pivot so as to compensate for minor variations in the degree to which the four corners of the concerned platen move vertically as a press operation proceeds.

2. In a hot press, in combination with the stationary head at the top, the movable cross-head at the bottom, and the intervening platens, structure applied to each of the four corners of the press comprising an outrigger beam having its inner end pivoted to the head for vertical swinging motion and having a radius bar extending as a pitman from the outer end to the cross-head, said beam being provided with a plurality of horizontal bores, one for each of said intervening platens, located parallel with the swing axis of the beam on .a common plane traversing said swing axis at equidistantly spaced intervals within the length of the beam, l3. respective pivot pin journaled in each :of said bores with a head end thereof exposed, said exposed ends presenting a through-opening drilled diametrically on :an axis normal to the bore, a respective headed hanger rod for each of said platens pivotally connected by its lower end to the platen and having its upper end received for vertical sliding motion through said through-opening of a related pivot pin, and a compression spring surrounding the rod between said head of the rod .and the exposed head of the pivot pin and acting in the open condition of the press to pass into the beam the hanging weight of the platen.

3. Structure according to claim 2 in which each alternate pivot pin has its head end projecting from one face of the beam while the head end of the intervening pivot pins project from the opposite face.

4. Structure according to claim 2 in which the connection from the lower end of each hanger rod to its related platen is a ball-joint pivot.

5. Structure according to claim 2 in which the head for each hanger rod is arranged for endwise adjustment thereon and comprises a thrust-taking nut and its backing complement of a lock-nut both threaded upon the rod.

6. In a hot press, in combination with the stationary head at the top, the movable :oross head at the bottom, and the intervening platens, structure applied to each of the four corners of the press comprising an outrigger beam having its inner end pivoted to the head for vertical swinging motion and having a radius bar extending as :a pitman from the outer end to the cross-head, and a plurality of headed hanger rods, one for each of said intervening platens, suspending the platens from the beam with the head ends thereof connecting with the beam at points equidistantly spaced along the length of the beam, said beam swinging through a relatively wide are which is approximately equally divided above and below a horizontal plane traversing the swing :axis of the beam, a re spective compression spring being provided for each of said hanger rods surmounting the beam in positions interposed between the beam and the head of the concerned rod, said springs having a spring characteristic such as will establish a fixed length therefor when the suspended weight is below a normal which exceeds, to la predetermined degree, the proportioned part of the hanger carried by such rod and permitting said length to be extended when the load to which the rod is subjected exceeds said norm.

Horton et ,al Feb. 2, 1926 Moore Feb. 19, 1952

Images