US 2187432 A
Description (OCR text may contain errors)
Jan. 16, 1940. M. A. POWERS J 9 PROCESS AND APPARATUS FOR THE MANUFACTURE OF INSULATING MATERIAL Filed Nov. 11, 1955 ENVENTGR I Patented Jan. 16, 1940 PATENT OFFICE PROCESS AND APPARATUS FOR THE MAN- UFACTURE OF INSULATING MATERIAL Milton A. Powers, Detroit, Mich.
Application November 11, 1935, Serial No. 49,265
This invention relates in general to heat insulation, and more particularly to heat insulating units, apparatus and methods of production thereof.
The high efiiciency and effectiveness of a. vacuum as a barrier to heat transfer is generally acknowledged, particularly where the temperature gradient is not too steep so as to introduce important losses through the mass by radiation. Where the temperature gradient is very steep, radiation preventive means are necessary. An example of the use of a vacuum as an insulator is the conventional thermos" bottle, or Dewar flask. If the principle of the Dewar flask were incorporated into structures, such as buildings, refrigerator cars, furnaces, etc., such structures would be highly eflicient as regards heat transfer; however, it would be decidedly impractical to construct such an insulated structure, due to the large space between the walls of the Dewar flask" and the enormous size thereof. Many attempts at such a construction have been made in the prior art; for example, as shown in Coleman patents, Nos. 946,772 and 958,095.
Therefore, a primary object of my invention is to provide, in a practical manner, an insulating material for a wall structure whereby a substantial vacuum is provided in said wall structure.
A further object is to provide an insulating means for a wall structure which provides in said wall a substantial vacuum and which is both practical and economical to manufacture and install.
A further object is to provide for a wall structure an insulating means comprising a quantity of independent vacuums, which, taken as a whole, comprise in effect a single large vacuum.
A further object is to provide for a wall structure an insulating means which is substantially free from deterioration caused by either age, temperature changes, moisture or vermin.
A further object is to provide an insulating material for a wall structure which may be poured into said structure, and when so poured, will completely fill said structure without subsequent settling and will substantially form a vacuum therein.
Efforts to obtain the results I obtain have been made in the prior art-an example being Coleman patent, No. 948,541-however, such efforts have been impractical for several reasons; the first and most important reason is that such insulating means has been costly and complicated to manufacture and install. A second important reason is that, in order for said prior heat insulating means to be efiicient, it is necessary to add auxiliary insulating means.
As noted in the Coleman Patent No. 948,541, the main insulating means is a quantity of hermetically sealed glass spheres having a vacuum therein. All of these spheres are of uniform size, and hence when placed in a wall structure the interstices are quite large and hence require an auxiliary insulating means, such as cement, to fill said interstices.
It is obvious that the creation of a vacuum in Colemans spheres, followed by hermetically sealing each sphere individually is a very costly procedure and produces a product which is very 15 susceptible to fracture in handling. Further, Mr. Coleman recommends that the spheres be placed in a certain manner in a wall structure, which, on its face, is impractical, as well as costly.
Therefore, a further primary object of my invention is to provide an insulating means consisting of a plurality of vacuum containers, said containers being composed of vitreous low heat conductive material, which are very inexpensive to manufacture, and may be poured into place in any wall structure, and in being so handled be free from danger of damage, due to rough handling.
A further object is to provide heat insulating means comprising a plurality of sizes of vacuum '3 containers whereby the smaller of the containers will fill the interstices between the larger.
A further object is to provide insulating means comprising vacuum containers, so designed as to shape and/or size that there will be little or 3 no space therebetween when said containers are poured into a space, thereby eliminating any possibility of air circulation.
As above stated, probably the most serious objection to the Coleman device illustrated in Pat- 40 ent No. 948,541 is the excessive cost of manufacture. It is necessary-according to this patent that the spherical ball first to be formed, then a vacuum created inside thereof and then the ball be sealed. This necessitates that each ball be handled individually for each operation.
Therefore, a further primary object of my invention is a manufacturing process for the manufacture of vacuum containers whereby the vacuum is automatically created and said containers'are formed and sealed in a continuous machine operation.
A further object is the provision of a method for creating containers having a vacuum therein which consists of introducing an expanded gas tube, solidifying the fluid material of said tube and automatically causing said gas or vaporto contract or liquefy upon reduction in temperature, thereby creating a vacuum in said tube' portion. A further object is the provision of apparatus for the manufacture of vacuum containers to be used as a' heat insulating means, whereby-the manufacture of said containers is continuous and automatic and said containers erect a predetermined size.
The above and further objects will more fully appear from the following description when taken in connection with the accompanying drawing wherein:
Figure 1 is a schematic view illustrating the apparatus and method for manufacturing the heat insulating means of my invention;
Figure 2 is an enlarged sectional view in part of the cutting wheels of Figure 1 while in operation;
Figure 3 is an end elevational view of one of the cutting wheels of Figure 2;
Figure 4 is an end elevational view illustrating an optional form of cutter wheel;
Figure 5 is a sectional view taken substantially along the line 5-5 of Figure 4; and v Figure 6 is a side elevational view similar to Figure 2, but illustrating the gear cutters of Figure 4.
In the interest of simplicity I have illustrated the vacuum containers of my invention as being formed by the introduction of steam into a column of glass. It is to be understood that either condensable vapors or expanded gases may be used without affecting the scope of my invention and such other gases or vapors are intended to be embraced in the appended claims. Likewise, other materials than the glass herein designated as the fluid, may be used without affecting the scope of my invention, as any material having the characteristic of plasticity at high temperatures and adapted to form a leak-proof container, upon cooling, may be used. I preferably employ glass as it has the advantages of cheapness, strength, freedom from objectionable deterioration, rigidity against settling and is unaffected by temperature, moisture or vermin.
Referring now to the drawing wherein like reference characters refer to like parts wherever they occur, and with particular reference to Figure 1, the apparatus for the manufacture of the heat insulating means of my invention comprises essentially a fluid heating chamber A, a gas or vapor preheating chamber B, vacuum container forming cutters C and an annealing oven D.
The fluid heating chamber A comprises an insulated container I having a central substantially cylindrical opening 3 therein which is open at its top and converges at the lower portion of said container into a circular aperture 5. Ad- Jacent the walls of said opening 3 are electrical heating elements I which are supplied with electrical current from a suitable source, such as 9. Inside of said heating elements I is a container H which conforms generally to the shape of opening 3, but which is of lesser diameter, thereby forming a substantially cylindrical space in' which said heating elements 'i'are contained. I
Containerv ii is preferably'made of a refractory material-and is provided at its upper end with a flange i3 in register with-the upper wall of. aperture 3 in container and at itslower end,
with-a comparatively small circular nozzle lb.-
The upper portion ofopenlngb is adapted to be sealed with a cover 11 whichmay or may not rest upon the upper flange It of container A plate I9 is placed concentrically under the nozzle l5 of container ii and has a central circular aperture therein of predetermined size.
Projecting into container II and terminating Just short of plate I9 is a tube 2| which connects with the preheating chamber 28.
For the purpose of illustration I have illustrated said preheating chamber as comprising a substantially cylindrical'insuiating casing 23 substantially closed at its opposite ends and containing an electrical heating coil 25 which is supplied with current from a suitable source such as 21. Inside of said coil 25 is a tube 29 through which is conducted the vapors or gases to be heated. Connecting tube 2| with tube 28 is a valve 3|, the purpose of which will be evident hereinafter. The tubing 29 and 2| is surrounded by insulation 33 from the point where said tubing leaves the preheating chamber 8 to the point where it enters the heating chamher A.
The apparatus thus far described is adapted to be operated as follows:
Current is passed through the heating elements I and 25 of the fluid heating chamber A and preheating chamber B and the necessary raw materials which are to be used to formthe outer casing of the heat insulating means of my invention are poured into the container During this preliminary period, of course, the nozzle l5 of said container is sealed. In the interest of simplicity I will hereinafter refer to the mateinch, and it is important that this pressure-be constant. It is also desirable that the steam flow to the .superheater should be in an upwards direction in order to minimize the possibility of carrying drops of water into the superheater or glass furnace, as when liquid water enters the system, the rapid vaporization of the water upon entering the heated zones results in a momentary increase of steam pressure with a consequent uneven expansion of the glass tubing which results as hereinafter described:
The valve 3| controls the rate of flow of steam into the tube 2| and, of course, as the steam flows through the tube 2| it tends to assume the temperature of the molten glass. When both the steam and glass are at proper temperature, the seal at the nozzle l5 of the container II is removed and the glass will flow by gravity through the central orifice in the plate l8. If the steam were not present this glass flow would produce a solid rod, but with steam also discharging centrally through the orifice of plate IS, a hollow column or continuous tube 35 of glass is formed which is filled with the superheated steam vapor.
The column 35 is fed as by gravity downwardly to the cutting and forming mechanism C which consists of two specially formed circular wheels 31, each wheel being identical with the other. Said wheels are revolved in opposite directions at exactly the same speed, being positively geared together. Each of the cutter wheels is provided with the same number and shape of teeth 39 and the driving mechanism for said wheels is so arranged that the point of contact between said wheels is in the plane of the axes of said wheels, which plane is horizontal. As the two cutter wheels 31 are identical and positively geared togather, they are initially adjusted so that each adjoining cutting edge 39 makes mating contact as the wheels revolve. Thereafter this relationship remains fixed regardless of the speed of rotation. While the cutter wheels may be on fixed centers for positive cutting, I preferably mount one wheel on a floating axis to allow slight movement toward or away from the other and provide an adjustable spring between said floating axis and a stop to supply the desired loading on the adjoining cutter edges.
The motive power (not shown) may be of any desired type; however, I preferably employ a variable speed electric motor which operates through a suitable gear reduction and gives more accurate control to coincide with the rate at which the glass tubing is drawn from the furnace.
The continuous tubing of glass 35 which is filled with the steam vapor is fed into the line of action of the mating cutters 31 and as it approaches the point of contact of said cutters it is grasped by mating cutting edges. As the edges advance, the opposite walls of the plastic tube approach each other, meet and are fused together under pressure. A moment later when the cutting edges reach the point of tangency of said wheels, the tube is cut off.
At this point then, there is a steam filled column extending from the point of tangency of the cutter wheels to the point of inception of the tube, which is, as before stated, at the orifice in the plate 19. When the cutters rotate for a distance of one tooth, a second point of cut-off will be reached, thereby forming a length of tubing 40 equal to the distance between two successive cutting edges of the cutter wheel, said length of tubing being sealed at both ends and filled with superheated steam. As the cutting wheels 31 continue to rotate, the sealed tube portion 40 will be released and further successive sealed tube portion 4|] will be formed. As said sealed tube portions or glass bubbles 40-as they will hereinafter be termed-are released by said cutter wheels, they drop into the annealing furnace D.
The annealing furnace D may be in any suitable form-the one illustrated here comprises an inlet H which leads into an inclined rotating cylindrical chamber l3 which is suitably heated as bygas burners 45. The temperature of said chamber decreases from the inlet end--where the temperature should preferably be somewhat below the hardening temperature of the glass being processed-to the outlet end 41 where the temperature may approach atmospheric.
It is evident from the above description that the diameter of the continuous glass tube 35, its wall thickness, cutting temperature, etc. are all subject to a number of factors, such as the temperature and viscosity of the molten glass, the steam pressure and quantity supplied, the size of orifice in the plate i9 and the relation of the end of the steam tube 2| to it, the lineal speed of. the cutters 31 and the temperature of the atmos phere and said cutters.
For example, increasing the steam pressure results in an increased diameter of the tube being blown and vice versa; also increased speed of rotation of the cutters draws the'tubing to produce a thinner wall of lesser diameter. Likewise, increased speed necessitates more steam to maintain the bore of the tubing. The fluidity of the molten glass will determine the approximate rate of flow of glass from the pot, but this in turn is affected by the drawing tension applied by the cutters. The time interval between the pot and the cutters will determine the plasticity of the glass for cutting and preferably should be held to a minimum to prevent excess cooling before cutting. Under some circumstances the cutters may preferably be heated by a gas flame, for example, to prevent excessive chill during the cutting operation. If the glass bubbles do not discharge freely from cutters, but tend to be retained, a rotating brush scraper or a jet of heated air may be used to advantage to dislodge them. It will be seen from the above that it is pos sible to manipulate the various controlling elements in the process to produce glass bubbles of a wide range of characteristics, such as diameter, wall thickness, strength, weight, etc. However, when once adjusted to the desired product, uniform production thereafter is automatic and con tinuous.-
The temperature within the molten glass container II will vary widely depending upon the analysis of the liquid contained therein and such temperature may be as high as 1800 degrees F.
When the continuous tube 35 reaches the cutters 31 it may have a temperature of, say,1500 degrees F. The vapor within said tube 35 is, of course, highly superheated and at approximately the temperature of the glass, yet it is under a pressure only slightly above atmospheric.
The glass bubbles 40 which leave the cutters 31, upon cooling. may become hard at, say, 1100 degrees F'. Thereafter, no change in internal volume can occur. As the bubbles are cooled still further, the vapor therein will contract and create sub-atmospheric pressure within said bubble. It is evident that, if the pressure was atmospheric within the bubble when the temperature thereof reached 212 degrees F. condensation of the steam vapor would occur and a vacuum would result. However, as the pressure is well below atmospheric at a relatively high temperature in the cooling cycle-as a consequence of the high superheat at the time of sealing-there will be an excellent vacuum upon reaching atmospheric temperature-which will be further enhanced by the condensation of the vapor. It is understood that a slight trace of vapor will remain inside of said bubbles; however, this presence may be neglected as the total amount is infinitesimally small, in view of the use of highly superheated steam at the time of sealing.
If desired, condensable vapors, such as steam just described, may be replaced by a gas-hydrogen for example, in view of its low atomic weight and poor heat conduction-as the fluid within the glass bubble. In such case, the vacuum will The size of the bubbles 40 will be dependent upon two things: first, the size of the tube entering the cutting wheels 31; and second, the distance between the successive cutting edges 30 5 on said wheels. In the particular embodiment shown I have illustrated the cutter wheels I! as having 27 cutting edges I9 thereon. Thus, said cutting wheels will produce 27 bubbles per revolution. By substituting cutting wheels having dif- 10 ferentiy numbered and differently spaced cutting edges, bubbles either larger or smaller than bubble 0 and either a greater or lesser amount may be obtained per one revolution of cutter than is obtained in the particular embodiment illustrated.
Generally speaking, a longer pitch between cutting edges will call for larger and heavier tubing and vice versa.
It is evident, however, that, if desired, long bubbles of narrow tubular sectionor going to 80 the other extreme-short bubbles having a large tubular section, may be obtained. Also, the contour of each finished bubble 40 may be varied within wide limits depending upon the shape and form of the cutter wheels. The wheels 31, previ- 86 ously described, will produce a pillow-like bubble,
as illustrated in Figures 2 and 3.
Referring now to Figures 4, 5 and 6, I have illustrated a cutter wheel which will produce a bubble 40a having rounded ends. The wheel 31 so of Figures 1 and 2 is provided with semi-cylindrical grooves laterally across the faces of said wheels. The wheels 31a of Figures 4, 5 and 6 are provided on their peripheries with a series of semi-spherical depressions 9, which aresur- 35 rounded with a narrow cutting edge 5|. Thus, there is a series of relief portions 53 on the periphery of cutters 31a, which is lower than the cutting edges II. It is necessary to provide the relief 53, as when the molten tube 35 enters the cutters 31a, and the rounded ends are formed, a substantially triangularly-shaped waste portion 55 of the tube will be severed.
The finished bubbles 40a together with the portions 55 may be put through the annealing 4,5 oven together, and later separated by water flotation or screening.
From the above and foregoing description, it is evident that I have provided a process and apparatus for producing vacuum filled containers of a low heat conductive material which is entirely automatic and the product produced thereby is a uniform in size, structure and properties, and is free from weak spots and able to withstand rough handling, andwill not deteriorate in use.
In practice, it may be desirable to furnishthe bubbles of my invention in a mixture of various sizes, in order that all interstices will be filled when said bubbles are poured into a wall structure. In such case, the preferable manner of go producing such a mixture is to mount a number of cutter members in line, each with its own molten tube feed, thus producing, for example, one large bubble, two medium bubbles and four small bubbles simultaneously from three sets of as cutters and three tube feeds. If the rotation is, say, 200 revolutions per minute, with the large cutter producing 27 bubbles per revolution and the other cutters twice and four times as many correspondingly, it will be seen that the hourly production will total more than 2,250,000 bubbles,
each complete in itself and having a high vacuum permanently sealed therein. The production of said three cutters may be directed into the same annealing oven and thus the proper mixture of 1 sizes and quantity obtained automatically.
In practice, the bubbles may be distributed in bulk to be poured in place as required. In addition to the effective insulating qualities the bubbles readily pack to entirely fill all available space. For instance, if it is desired to insulate 5 the walls of an old building, it is merely necessary to prepare an opening in the wall thereof through which the bubbles may be poured by gravity. As they present smooth rounded surfaces, there will be little or no resistance to their sliding one on 10 the other or along the wall surfaces. Thus they will completely fill all available space including the underside of window frames and other spaces which are hard to fill with other well-known insulations, such as mineral wool, asbestos, wood 15 flbre and the like. As my bubbles are non-compressible, it is impossible to insert more than the required amount as is frequently done in the case of fibrous material where excess material is forqd into place, thus impairing the insulating ability. so Likewise, the inherent strength of the glass, as formed, makes it capable of withstanding any reasonable load pressure without breakage.
The bubbles of my invention may be distributed in bulk, or, if desirable, they may be incorporated 25 in blocks or slabs of any desired shape or size. In such case, molds may be made to the desired size, filled with the bulk insulation, heated to the softening point of the glass, following which theinsulation may be reduced in volume by inward no movement of a wall of the mold to flll the entire space of the block or slab, which, upon cooling, produces an integral block or slab.
It is evident that the details of the equipment used in my process may vary greatly without 35 affecting the results. For example, while I have described an electrically heated fluid heating chamber, a gas-fired chamber will accomplish the same results. Likewise, whereas I have described a method of manufacture wherein the molten 4o tubing flows from the bottom of the heating chamber, the process may be reversed and the molten tubing pulled upwardly by the cutter wheels. Further, the preheater B may be dispensed with, if proper care is taken, thus allowing the fluid to obtain its superheat while passing through the molten liquid. The term "fluid as used herein and in the appended claims is intended to be generic to either a vapor or gas.
The invention may be embodied in other speg0 cific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the s appended claims rather than the foregoing description and all changes which come within the meaning and range of equivalency of the claims are, therefore, intended to be embraced therein.
What is desired to be secured by United States 00 Letters Patent is l. The process of manufacturing hollow, sealed containers; comprising continuously forming and flowing a tube of molten material such as glass from an orifice; continuously introducing a gase- 05 ous fluid into said tube as it is being formed; successively closing and shearing said fluid filled, hollow tube at intervals along its length while it is in a hot and plastic state, to form a plurality of individual fluid filled containers; and cooling said 70 containers, thereby solidifying the walls of said containers and reducing the pressure of said fluid.
2. A simple process for the production of vacuumizedvitreous containers, comprising the steps of molten vitreous material in a continu- 15 aromas ous stream through an orifice while simultaneously injecting a gaseous fluid at constant low pressure and very high temperature into said material adjacent and centrally of said orifice, whereby a hot plastic tube of uniform cross-sectional area extends from said orifice, severing and sealing said tube continually during its travel and while it is hot and plastic into hollow sections to thereby produce smooth sealed containers, and cooling the walls of said containers to solidification.
3. In the process defined in claim 2, said cooling step including an annealing phase for gradually bringing the containers toward the temperature at which they become hard.
4. In a process of the character described, for manufacturing hollow containers from a liquid or plastic vitreous material that isrigid and impervious under atmospheric conditions, the steps of passing said material downwardly through an orifice while simultaneously blowing a stream of gaseous fluid under constant pressure into the material centrally oi the orifice, permitting the passed material to hang temporarily in the form of a vertical tube below the orifice while continuously moving downwardly into a cooling medium, the pressure of the fluid being correlated with the pressure and temperature conditions of the cooling medium to govern the size of the vertical tube, and sealing said tube into a plurality of closed hollow sections of predetermined shape by the simple act of pinching the tube at intervals along its length as it travels and while it still is in substantially plastic form.
5. A process for the production of vacuumized insulating pellets or the like from thermoplastic material that is rigid and frangible under normal atmospheric conditions, comprising the steps of flowing said material in molten condition in the form of a thin-walled tube at substantially constant speed and without'interruption simultaneously, injecting low pressure fluid into the tube to provide the tube with a hot gaseous core of relatively large cross, section, and closing and dividing said flowing tube at intervals along its length while hot and prior to attainment of a frangible condition by said material, whereby pellets are formed having smooth and thin rigid u walls surrounding relatively large spaces, and
cooling the pellets to atmospheric temperature whereby subatmospheric pressure is created in the interior of the pellets.
6. In the process defined in claim 2, said gaseous fluid comprising a. vapor that is condensible under atmospheric temperatures.
'I. The hereinbefore described method, comprising continuously issuing glass from a molten bath in tube form and continually cutting and closing such tube at intervals along its length into short hollow lengths while it is still sufiiciently plastic to be closed by the cutting operation, whereby the tube tube is closed at both sides oi the plane of severance by the act of severance.
8. In the method defined in claim '7, supplying the issuing tube with a core of hot gaseous fluid, and utilizing the act of severance to sealsmall amounts of said fluid within said short lengths.
9. The combination with a container for molten glass, having an outlet, of a mandrel coaxial with the outlet and cooperating therewith to cause the glass issuing therefrom to assume a tubular form, and combined pressing and severing elements on opposite sides of the path of movement of the tube so formed, said elements being located at a distance irom the outlet greater than the length of the pieces severed, but sufiiciently close thereto that the tube at the time the elements act thereon is at a temperature to cause the end walls of the tube to cohere when pressed together.
comprising a continuous series of alternated cutas ters and pockets.
11. In apparatus for the manufacture of hollow sealed containers from material such as glass or the like, a heating chamber for the material; means for heating said chamber to melt the material; said chamber having an orifice; means to supply expanded gas or vapor at said orifice for causing the molten material to emerge from said orifice as a hollow tube; oppositely rotating, meshing wheels, each having a multiplicity oi. closely spaced mated cutting elements, in line with the flow of said hollow tube whereby said tube is successively closed and sheared at the point of closing.
MILTON A. POWERS. a