US 2233350 A
Description (OCR text may contain errors)
Feb. 25, 1941. w. L. NELSON VACUUM LIFT DEVICE Filed Oct. 20, 1939 2 Sheets-Sheet 1 .N S. NN 8 WN. Q.,
N 0 S RH Y ON E TLN N R m .m mw .A mm W Y B w Feb. 25, 1941. W. L Nr-:LsoN 2,233,350
VACUUM LIFT DEVICE Filed oct. 2o. 19:59 2 shuts-sheet 2 Nm om am mv INVENTOR W/LL /M L. NELSON BY ATTORNEY Patented Feb. 25, 1941 UNITED STATES VACUUM LIFT DEVICE William L. Nelson, South Holland, Ill., assignor to United States Gypsum Company, Chicago, Ill., a corporation of Illinois Application October 20, 1939, Serial No. 300,327 s claims. (c1. zei-cm' This invention relates to lift devices, and has reference more particularly to vacuum lift devices suitable for lifting and transporting sheets of flexible material, such as asbestos-cement sheet shingle stock.
In the manufacture of asbestos-cement shingles, siding and industrial sheet material of all kinds, it is customary to manufacture large sheets of the asbestos-cement stock material.
After forming the sheets, they are lifted from the forming conveyor bya vacuum lift box and deposited on. a conveyor which carries the sheet through the platens of a hydraulic press. A wood grain imprint is pressed onto the top surface of the sheet by the press and the conveyor then transfers the sheet to the delivery side of the press. Here another vacuum lift box engages the grained upper surface of the -sheet and transfers the sheet to a skid to permit the cement to set over a period of several hours. In the vacuum lift boxes previously used, the lower surface'of the box has been covered with porous screen wire backed up by suitable frame work. It has always been thought that the vacuum must be applied to the entire face of the sheet by the use of the screen wire. However, it has been found. that the press of the screen on the plastic embossed surface of the sheet, leaves the imprint of the wire meshes on the protruding 3 embossed ridges of the surface of the sheet.
These wire mesh imprints on the sheet are objectionable and decrease the salability of the resulting shingles.
An object of the invention, therefore, is to` 35 provide a vacuum box in which the objectionable screen wire is eliminated and a flat sheet with peripheral vacuum applying holes is used.
Another object of the invention is to decrease the weight and improve the lifting powerof a 0 vacuum lift box.
A further object of the invention is to produce an embossed sheet ofasbestos cement which is free of screen wire imprints; also to improve vacuum lift boxes and asbestos cement sheet 45 products in other respects hereinafter specified and claimed.
Reference is to be had to the accompanying drawings forming a part of this specification, in which Fig. l is a plan view of the vacuum lift box,
Fig. 2 is a sectional elevation through the box taken on line 2-2 of Fig. 1,
Fig. 3 is a bottom view of the box,
Fig. 4 is a sectional elevation on an enlarged 55 scale taken on line 4-4 of Fig. 1, and
Fig..5 is a diagrammatic view showing the piping and other apparatus associated with thebox.
Referring to the drawings by numerals, the vacuum box III is connected by a pipe II to a vacuum tank I2 having av drain valve I3. A three way valve I4 is provided on the pipe II to apply the vacuum for liftinga. sheet I5, said valve I4 also being arranged to release the vacuumto deposit the ysheet at a desired point. A pipe I6 connects the tank I2 to a vacuum 10 pump Il,
'I'he box I0 comprises transverse channel ,beams or frames I8, I9 and 20 secured to longitudinal channel beams or frames 2l by angle r cups z2 and bolts 2s. u-bars 24, preferably four 1 in number, are provided with flattened ends which are secured to the frame members I8, 20 and 2I by bolts 26. A hoisting chain 21 is secured at one end to each of U-bars 24, the opposite ends of said chains being connected to a 20 ring 28. A pneumatic or other type of hoist not shown, may be attached to the ring 28 to lift the vapparatus carrying a sheet of material. End channel frames 29 are secured to the ends of channels 2| by angle clips 30.
Metal bars 32 extend around the periphery of the box below outstanding lower flanges 33 formed on the channel frames 2| and 29, being secured thereto by bolts 34. A longitudinal groove or air passage 35 extends along the bottom face of each bar 32 and branch pipes 36 are connected at intervals to the inside of each bar 32. The branch pipes 36 join in an air manifold 31 which is joined by flexible hose 38 to the vacuum tank I2. A metal sheet 39 is secured about its pe- 3* riphery by screws 40 and bolts 34 to the channel anges 3 3. Screws 4I secure the sheet 39 to the channels I8, I9 and 20 intermediate the edges of said sheet 39. A series of air holes 43`are formed around the periphery of sheet 39, said holes registering with the grooves 35. In order to seal the box around the periphery, with the sheet of asbestos-cement shingle material I5, I attach a thick strip of medium soft rubber 45 to channels 2| and bars 32 by a metal strip 46 and screws 41 and 48 respectively. A strip of hard rubber 49 is interposed between the rubber strip 45 and metal strip 49 in order to back up and stiifen the rubber strip 45. The lower edge of rubber strip 45 is provided with a bevel 50 50 which forms a sealing edge 5I on the bottom of said strip 45. I prefer to make all metal parts, where possible, of Dow metal, a. magnesium base alloy, because of its lightness and strength. Other light weight metals may of course be used.
It will be seen that as Ithe sheet 39 is imper- -forate or air-tight inside the peripheral air holes 43. no defacing marks will be produced on the upper surface of the sheet I5, as were produced by the older type of lift box in which screen wire was used on the lower surface of the box. thermore, the vacuum is evenly applied over the face of thesheet I5 when the air holes 43I are arranged only around the periphery of the sheet 39, contrary to the accepted belief that air holes have to be located throughout the area of` the sheet.
I would statev in conclusion that, while the illustrated example constitutes a practical embodiment o1' my invention, I do not wish to limit myself precisely to these details, since manifestly that same may be considerably varied without departing from the spirit of the invention as dened inthe appended claims.
Having thus described my invention, I claim as new and desire to secure by Letters Patent:
1. In a vacuum lift device, a substantially imperforate rigidly held sheet of material, sealing means around the periphery of said sheet for forming a substantially air-tight seal with a supported sheet of exible material, said first sheet being provided with a series oi" peripheral air holes adjacent said sealing means, and means i'or applying vacuum through said holes to draw said iiexible sheet against said nrst sheet and said sealing means. Fur- 2. In a vacuum lift device, a supporting frame, a. rigid bar member extending about the periphery of said frame, a substantially imperforate sheet rigidly supportedby said frame and bar member, said bar member having a longitudinal vslot formed in the bottom surface thereof, air
holes around the periphery of said sheet and communicating with said slot, sealing vmeans around theperiphery of said frame', and means for appyling vacuum to said slotted bar and sheet so as to draw a flexible sheet oimaterial against said sealing vmeans and said rst sheet.
s. In a vacuum nft device, a sheet of rigidlyy held material having air holes only around the periphery thereof, means for attaching said sheet to a hoist, sealing means adjacent the pe-l -riphery of said sheet, and means for applying a vacuum to said holes so as to draw a flexible sheet. of material against saidfirst sheet and said sealing means.
` WILLIAM L. NELSON: