US2923068A - Drying die - Google Patents

Description

Feb. 2, 1960 R. WELLS DRYING DIE Filed Jan. 13. 1958 INVENTOR 1 07M %e%/,

BY RIL- w LOCK-5 ATTORNEY DRYING our,

Roger Wells, Stamford, Conn., .assignor to Diamond National Corporation, a corporation of Delaware Application January 13, 1958, Serial No. 708,417

2 Claims. (Cl. 34-104) The present invention relates to a drying die for use in conjunction with a molded pulp machine, and more particularly to a drying die made of sheets of metal joined together.

In the molding of articles of paper pulp, the articles are formed by depositing a layer of pulp from a liquid slurry onto a forming die, and then transferring the article to a drying die, in order to allow the article to dry out and be of the proper shape.

Drying dies in use today have several known disadvantages: they have lower than desirable heat transfer characteristics, and they are heavy, bulky and expensive. In addition, dies in use at the present time are so constructed that water from the article being dried remains in contact with the surface of the die for a relatively long time. This is the result of either a squeezing action exerted by a matching die or merely the vacuum ap plied to the die, but in either case there is a build-up of deposits on the die surface. This build-up necessitates the stopping of not only the molding machine of which the dies are a part, but also certain allied equipment. It will be readily understood that the stopping of the equipment is economically undesirable, so that much gain will be derived from a construction which permits longer periods of operation and consequently less frequent, or no, down times.

It is an object of the present invention to provide a drying die which will have improved heat transfer characteristics.

It is a further object of the present invention to provide a drying die which is light, compact and relatively cheap to manufacture.

It is a further object of the present invention to provide a drying die which will substantially eliminate the necessity for cleaning.

Other objects and the nature and advantages of the instant invention will be apparent from the following description taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a plan view of the drying die made in accordance with the present invention.

Fig. 2 is a sectional view taken on line 2-2 of Fig. 1.

Referring now to the drawings, there is shown in Figs.

1 and 2 a drying die comprising a back plate 12 and having a ring 14 extending therearound. Supported on the ring 14 is a lower die plate 16 and above that an upper die plate 18.

Certain of the regions of the upper die plate 18 and lower die plate 16 are joined together. Specifically, the plates 16 and 18 are joined together, as by welding, throughout the spiral area 20. Through the welded spiral area 20 there extend a plurality of drainage holes 22, these holes 22 extending completely through the lower plate 16 and upper plate 18. Whereas the plates 16 and 18 are joined together and are in intimate contact along the area 20, between the convolutions of the area 20 there is a second area 24 in which the plates 16 and 18 are separated from each other, as best seen in Fig. 2.. A

ited States Patent Patented Feb, 2, 15%0 heating fluid inlet duct 26 is connected to the area 24 at one end thereof and an outlet duct 28 is connected to the area 24 at the other end thereof, it being understood that due to the separation of the plates along area 24, there is a continuous passageway formed in the drying die 10, and it is to this passageway that the ducts 26 and 28 are connected. The ducts 26 and 28 extend through appropriate holes in the back plate 12, as shown in Fig. 2.- There may also be seen in Fig. 2 a conduit 30 connected to the back plate 12, and through this conduit 30 either vacuum or blow-off air is supplied, as desired.

It will be understood that the die constructed as above may be fabricated rapidly and cheaply from known materials and techniques. For example, the upper and lower plates 16 and 18 are preferably made up of noncorrosive material, and may be made initially of two plates substantially contiguous throughout that area, and formed in the desired pattern; fluid under high pressure may then be caused to flow through the unwelded area 24, and because of the greater ductility of the lower plate 16, it will be deformed into the manner indicated in Fig. 2. Alternatively, the plates 16 and 18 may be formed, as by stamping, to the necessary shapes, and then welded together to provide the structure shown in the figures of the drawing.

When the drying die of the present invention is in use on a drying table, a relatively wet molded pulp article will be placed upon the die 10 for drying. A heated fluid, such as steam, will be caused to flow into the inlet duct 26, through the conduit formed by the area 24, and steam and condensate caused to-flow out of the outlet duct 28. The heat thus transferred to the drying die 18 from the heated fluid will cause the article on the drying die 18 to dry out. In certain installations, the holes 22 may not be necessary, and thus may be eliminated, along with the conduit 38. Alternatively, the holes 22 may be provided and the liquid from the article permitted to pass therethrough and into the atmosphere, the back plate 12 and conduit 30 not being necessary in this configuration, also. However, in those installations where the sucking away of the liquid from the article is deemed necessary, a vacuum will be applied through the conduit 30 to aid in drawing the liquid from the article through the holes 22. When the drying of the article has been completed to the desired degree, blow-off air may be supplied through the conduit 30, this air passing under pressure through the holes 22 and causing the separation of the article from the die 10.

It will be understood that although the areas 20 and 24 have been shown and described as spiral areas, this particular configuration is'only preferred, it being only necessary for the functioning of the device that the area 24 simply provide a passageway between the inlet and outlet ducts.

It will be obvious to those skilled in the art that various changes may be made without departing from the spirit of the invention and therefore the invention is not limited to what is shown in the drawings and described in the specification but only as indicated in the appended claims.

What is claimed is:

1. A drying die comprising a back plate, a ring-like member secured to said plate at the periphery thereof, a pair of die plates secured to said ring-like member, said die plates being secured together in sealed relationship at their peripheries, one of said die plates being an upper shaped die plate adapted to have a wet molded pulp article applied directly onto the upper surface thereof, the other die plate being a lower die plate, said lower die plate being of undulated configuration relative to the upper die plate and having the peaks of the undulations secured to the underside of the upper die plate, said die plates being separated from each other between the peaks of the undulations to provide space between said plates, first and second spaced ducts connected to the lower die plate and communicating with said space, a third duct connected to said back plate, and drainage holes through the contacting regions of said plates.

2. A drying die comprising a back plate, a pair of die plates of impervious material secured to said back plate, said die plates being secured together in sealed relationship at their peripheries, one of said die plates being an upper shaped die plate adapted to have a wet molded pulp article applied directly onto the upper surface thereof, the other die plate being a lower die plate, said lower die plate being of undulated configuration relative to the upper die plate and having the peaks of the undulations secured to the underside of the upper die plate, said die plates being separated from each other between the peaks of the undulations to provide space between said plates,

first and second spaced ducts connected to the lower die plate and communicating with said space, a third duct connected to said back plate, and drainage holes through the contacting regions of said plates.

References Cited in the file of this patent UNITED STATES PATENTS 1,582,714 Wells Apr. 27, 1926 1,847,573 Rupp Mar. 1, 1932 2,095,118 Basler Oct. 5, 1937 2,146,749 Knight Feb. 14, 1939 2,349,469 Sloan May 23, 1944 2,482,330 Dudzinski Sept. 20, 1949 2,727,632 Mack Dec. 20, 1955 2,803,889 Ushakofi Aug. 27, 1957 2,856,164 Adams Oct. 14, 1958

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