US 3358059 A
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Description (OCR text may contain errors)
Dec. 12, 1967 R. P. SNYDER 3,
METHOD OF FILLING ENCLOSURES WITH LOW DENSITY PARTICULATED MATERIAL Flled Aprll 20, 1964 I I N VEN TOR. Roerfl. Snyder 14 TTORNE Y United States Patent 3,358,059 METHOD OF FILLING ENCLOSURES WITH LOW DENSITY PARTICULATED MATERIAL Robert P. Snyder, Saginaw, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed Apr. 20, 1964, Ser. No. 361,020 3 Claims. (Cl. 264-51) This invention relates to a method of depositing a low density particulated material between the walls of a confining body. More particularly the invention concerns a method wherein the material is blown into the enclosure as air is vented therefrom by means of an elongated tube.
Insulated enclosures such as refrigerator doors can be manufactured at high speed using a blanket of an insulating material, e.g. glass fibers or a foamed plastic. The insulating blanket cut to the proper shape for a refrigerator door, for example, is placed on the outside panel of the door then the inside panel is secured in place, forming the insulated door. These door components are easily handled and the operation can be carried out quite rapidly, enabling a high output for the manufacturing operation.
Interest has arisen in the use of particulated insulating materials which can be poured or blown into the thin hollow walls of an insulating body. Attempts to fill such enclosures with a low density particulated material by pouring it into the enclosure and depending upon gravity sedimentation to fill the cavity have been found to require long periods of time to get a complete fill-up with the low density material. These long fill-up times substantially decrease the output capacity of the manufacturing facility.
One method which has been used to overcome the shortcomings of the gravity fill method is that of pressure filling wherein the insulation is blown into the enclosure with vent holes spaced thereabout for the escape of the transporting air. Although this method is faster than the gravity fill method, the amount of time saved is dependent to a great extent on the number and size of the vent holes. These holes should be hermetically sealed following the filling step to prevent the loss of insulation and the entrance of moist air into the enclosure, therefore a time consuming hole sealing step is required.
I have discovered a method of filling enclosures with an insulating material which provides a complete fill-up in no more time than is required to position an insulating blanket between the walls of the enclosure. Additionally, this method which utilizes a pressure fill-up does not require numerous vent holes for the escape of transporting air. The method can be practiced with a single fill hole and only one vent.
The method of filling enclosures according to this invention involves the use of an elongated vent tube which can be inserted into the enclosure prior to filling then withdrawn after the insulation has been placed. The tube, which may extend across the greatest dimension of the enclosure and is slotted throughout its length, permits the escape of air from the enclosure over a large area, thereby effectively functioning as a filter mat which promotes the deposition of insulation uniformly throughout the enclosure.
The figure illustrates the practice of this invention in the insulation of a refrigerator door.
Referring to the figure, refrigerator door 20, shown Patented Dec. 12, 1967 ICC? partly in cross-section, is filled with particulated insulating material 24 from pressure tank 13, shown partly in cross-section. The refrigerator door has vent hole 27 and filler hole 28 positioned on the edge. Vent tube 21 extends through the vent hole, with tapered neck 22 providing an air-tight seal between the vent tube and the sides of the hole. Tapered end 19 on nozzle 18 in filler hole 28, produces an air-tight seal with the sides of the hole.
Low density particulated insulating material in pressure tank 13 is transported to the cavity in the door by a stream of air delivered to the pressure tank by blower 12. Air leaves the pressure tank through dip leg 16, canying with it the low density insulation in a fluidized stream. Flexible hose 17 having one end connected to the dip leg and the other end connected to nozzle 18 provides a convenient means of transferring the insulating material to the member to be insulated.
The fluidized stream of insulation entering the cavity within door 20 flows through the cavity as air enters slots 23 in vent tube 21 and escapes through the end of the vent tube extending from the door. The end of the tube inside the door is closed to prevent the entry of insulation. In this manner the fluidized solids filter out of the air stream against the slotted vent tube. In the event one zone becomes filled With insulation before the door is completely filled, the continued movement of air through the remaining voids to the vent tube results in a complete and rapid fill-up. Although it is not essential in filling cavities, it frequently is beneficial if the vent tube lies generally along one side with the filler hole at the opposite side so that the low density material traverses the cavity in the filling operation.
Blower 12 desirably is a high volume, low pressure air mover so that large volumes of the low density material can be transported in a short time without danger that excessive pressure will deform or balloon the body being filled. When the door cavity has been filled as evidenced by no further movement of insulation even though air continues to vent from tube 21, valve 26 is closed, cutting off the flow of air and insulation. Observation window 25 may be provided in the filler hose near nozzle 18 to aid in determining when the cavity is filled. The vent tube may then be withdrawn from vent hole 27. The void in the body of insulation produced when the tube is withdrawn ordinarily will be compensated by the slight overfill at the pressure of the transporting air. The filler nozzle may then be withdrawn from filler hole 28 and both holes plugged to prevent the loss of insulation.
A means for replenishing the supply of insulation in pressure tank 13 is shown in the figure. Insulation stored in hopper 11 flows by gravity or with a slight air pressure through leg 14 and into the pressure tank through valve 15 when blower 12 is shut off and the pressure is vented from tank 13. Valve 15 may be slightly springloaded to remain in the closed position. In the alternative the valve may be remotely operated by a solenoid or the valve may be located in leg 14 above the pressure tank so that it can be operated manually.
Vent tube 21 can embody any of several mechanical designs. Multiple discontinuous slots as shown in the figure is a convenient design. The width of the slots is not wide enough to admit the particles of insulation being used. In addition to the longitudinal slots illustrated, it may be possible to use lateral slots with equal facility. A tube having slots or perforations large enough to pass the insulation can be covered witha screen having a mesh small enough to filter out the insulation. It is' preferred that the tube extends across the entire length or greatest dimension of the door or other enclosure being filled.
This invention is particularly useful in filling cavities such as those in refrigerator doors with particles having a bulk density less than about 8 or 10 pounds per cubic foot. Common insulating materials having a low density in this range are perlite, vermiculite, ground cork, chopped glass fibers, small hollow or foamed plastic beads and the like. A plastic material which has been used to insulate refrigerator doors according to this invention is expanded beads of polystyrene having a bulk density less than 1 and typically about 0.7 pound per cubic foot. The very low density of this material makes it extremely difiicult to obtain a complete fill-up of the irregular and thin cavity inside a refrigerator door when the filling is accomplished by gravity sedimentation.
A refrigerator door with a cavity having a volume of approximately 2.5 cubic feet was completely filled with these low density polystyrene beads in 10 seconds through a one inch diameter fill hole and a one inch diameter vent hole. A slotted vent tube extending the length of the door and having three rows of inch wide slots filtered the beads from the transporting air. The same size door with multiple vent holes uniformly spaced thereabout in place of the vent tube inside the cavity required about 90 seconds to fill completely when the beads were blown in the filler hole.
The use of the pressure tank illustrated in the figure for fiuidizing and conveying the low density material is illustrative only and is not intended to be limiting. Another method which may be used is that frequently used with pneumatic conveyors wherein the solids are aspirated into the flowing stream of air. Compressed air discharged through a throat with a side connection to the supply of insulating material will aspirate the light-weight insulation into the stream of air leaving the throat. Care must be exercised with fragile insulating materials to avoid air velocities which produce excessive turbulence, causing attrition of the materials.
Although this invention has been described principally by reference to the insulation of refrigerator doors it should be understood that the method can be used to fill numerous types of cavities with insulation. The walls of houses can be insulated conveniently and efficiently in this manner using bulk insulation after the outside sheathing and interior wall board have been installed. After making two holes about one inch in diameter near the top of the sheathing between each of the wall studs, a flexible plastic vent tube can be inserted through one of the holes to a point near the bottom of the wall cavity. The filler nozzle is then placed in the other hole and the insulating material blown in until the cavity is full. The holes may be plugged or covered with siding after the nozzle and vent tube are removed.
Another important use for this method of handling low density resins is that of mold filling. Low density particulated thermoplastic resins such as partially expanded polystyrene beads having a bulk density of about one pound per cubic foot are used extensively in molding insulated containers such as picnic ice chests. A mold is filled with the partially expanded beads then heated to expand the beads further, filling the interstices therebetween and fusing the thermoplastic particles into a composite body. The method of this invention can be used to advantage in filling these molds by providing a filler hole and a vent hole in the mold. In rigid molds where deformation of the cavity enclosure by overfilling is not a problem, the filling can be continued as the vent tube is withdrawn to compensate for the void which would otherwise be left by the tube,
The method also has utility in the manufacture of .flotating equipment and in the stabilization of resilient hollow-walled panels.
1. The method of depositing low densityparticulated material between walls which form a substantially airtight enclosure, except for vent and fill holes hereinafter provided, for said material comprising:
providing a vent hole and a fill hole in said walls;
inserting an elongated slotted vent tube through said vent hole, said vent tube extending substantially the entire length of said enclosure and having slots throughout its length;
inserting a fill nozzle in said fill hole;
discharging an air stream containing said low density particulate-d material from said fill nozzle into said enclosure and ventingthe air stream without the low density particulate material from said vent tube as said material deposits in said enclosure, whereby the slotted vent tube effectively functions as a filter mat promoting the dispersion of insulation throughout the enclosure, until no more material can enter said enclosure; then withdrawing said vent tube and removing said fill nozzle and closing said fill and vent holes.
2. The method of filling the cavity inside a refrigerator door with a particulated insulating material comprising:
providing a vent hole and a fill hole in the wall of said door,
inserting a vent tube in said vent hole whereby said tube closes said hole and extends substantially across the cavity in said door, said vent tube having openings throughout its length to filter said insulating material from a stream of air, inserting a nozzle in said fill hole,
blowing through said nozzle into said cavity a stream of a low density particulated insulating material fluidized in air whereby said insulating material filters out of said stream against said vent tube as the air from the nozzle discharges. from said cavity through said vent tube and continuing to blow said fluidized stream through said nozzle until said cavity is completely filled with insulating material filtered therefrom by said vent tube,
discontinuing the fiow of air through said nozzle, then Withdrawing said vent tube and nozzle from said door and closing said vent and fill holes therein.
3. The method of filling a cavity in a mold with a low density partially expanded thermoplastic resin comprising:
providing a vent hole and a fill hole in said mold;
inserting an elongated vent tube in said vent hole, said tube extending substantially the entire length of said cavity and having slots throughout its length; inserting a fill nozzle in said fill hole;
discharging an air stream containing said low density resin from said nozzle into said cavity and venting the air stream without the low density resin from said vent tube as said low density resin deposits in said cavity, by the filter action of said vent tube, until no more resin can enter said cavity;
withdrawing said vent tube while continuing to dis charge said air stream into said cavity until said vent tube has been displaced by said low density resin;
then withdrawing said fill nozzle and closing said vent and fill holes.
References Cited UNITED STATES PATENTS 1,941,304 12/ 1933 Heylandt 220-86 2,128,336 8/ 1938 Torstensson 52-743 2,138,104 11/1938 Kellogg 220-86 2,140,559 12/1933 Sculley el al. 220-86 2,330,983 10/ 1943 Mathey 220-86 2,439,601 4/1948 Heritage 52-743 2,439,602 4/ 1948 Heritage 52-743 (Gther references on following page) OTHER REFERENCES FOREIGN PATENTS 2,439,603 4/ 1948 Heritage 52743 2,439,604 4/1948 Heritage 52-743 3513;; 2,543,734 4/1951 M y 22086 5 ,432,227 19 2 c 2,576,977 12/1951 Stober 26453 OTHER REFERENCES 2,962,110 11/1960 Depman 264-86 2,871,895 3/1959 RektOrys 141290 Franson, G. R., Fabrication Methods for Expandabh 2 9 2 110 11 19 0 Depman 22 36 Polystyrene, in Plastics Technology, July 1956, vol. 2 3,059,251 10/1962 Pollock 264-51 10 3,071,287 1/1963 Gran 220-86 ALEXANDER H. BRODMERKEL, Primary Examiner 3,222,718 12/1965 Meyer 185 ROBE F HI E E 3,225,126 12/1965 Bridges et a1. 26451 RT T mmme" 3,250,420 5/1966 Kohn i 220-86 15 P. E. ANDERSON, Assistant Examiner.