US1655714A - Machine and method for making wall board - Google Patents

Description

K. SLIDELL MACHINE AND METHOD FOR MAKING WALLBOARD Jan. 10, 1928.

Filed April 1926 Patented Jan. 10, 1928.

UNITED STATES PATENT OFFICE.

KEMPER SLIDELL, OF MADISON, WISCONSIN,

C. F. BURGESS LABORATORIES, INC., OF DOVER, DELAWARE, A CORPORATION OF DELAWARE.

assre'non, BY mssnn essreumnn'rs, 'ro

Application filed April 20, 1926. Serial No. 103,213.

scribed in the pending application, of my coworkers, Howard F. Weiss and Ralph F. Norris, filed June 17, 1924, Serial No. 720,510.

The object of my invention is to construct a machine which is adapted to continuously make wall board with the minimum amount of labor and waste. Further objects and advantages will be apparent from the following description.

A practical embodiment of the machine is shown diagrammatically in the accompanying drawings. Fig. 1 is an elevation of the wall board machine, Fig. 2 is a plan view of the machine together with the accompanying apparatus, and Fig. 3 is a cross-section of the heat-treater on the line 3-3 of Fig. 1.

My invention applies especially to wall boards and similar structures made by puffing by heat a doughlike mixture of alkali silicate andfiller. The heat treating apparatus may also be used for boards made with an alkali silicate and filler core but which are not puffed. In wall boards of the puffed type the mix is usually pufi'ed between two facings, such as chip board liners. The dough-like mix is made of about one part of alkali silicate, such as sodium silicate, and about two parts of powdered filler, which may be dolomite, limestone, slate, ashes, and the like. To this a small amount of soap usually is added to help the puffing action.

This doughlike mix is rolled between the two facings to the proper thickness afterwhich it is subjected to a heating operation, preferably between steam heated platens. The sudden vaporization of the water contained in the dough-like mix"containing sodium silicate causes a puffing action which results in a porous bread-like structure. The rapid escape of the steam soon causes the structure to harden. This heat treatment may be continued to dehydrate the silicate still further and thereby make it more water resistant. By using higher temperatures than are practical withsteam, im-

proved results are obtained, this procedure requiring a secondary heat-treating operation. My apparatus and method contemplate the use of such a secondary heattreater.

- chined on the surfaces exposed to the In accordance with my present invention the operations of puifing and subsequently heat treating are carried out in the apparatus of Figs. 1 and 2. The dough-like mix is made in any suitable mixer 1 and delivered by conveyor 2 to hopper 3 which is placed above a pair of rolls 4. Suitable facings or liners 5 and 6 such as chipboard are threaded through the rolls, and the mix as it leaves the hopper is squeezed between the facmgs to a predetermined thickness depending upon the desired weight and thickness of the finished board. The ends of the hopper 3 are spaced back from the edges of the facings and from the ends of rolls 4 so that the dough-like mix will not squeeze ever the edges of the facings. Should this happen the trim wires 7 remove this surplus. From squeeze rolls 4 the board passes through pufling apparatus 8 and heat-treater 9 being pulled by pull rolls 10 at a .rate which allows the board to be subjected to the required heat treatment for the proper length of time. The use of pull rolls instead of conveyors constitutes a novel feature of my apparatus. The surface speed of the squeeze rolls 4 must be about equal to the surface speed of the pull rolls 10 so that the green board between the squeeze rolls and pufling apparatus is neither sub ectedtO too much tension nor becomes too slack.

The puiiing apparatus 8 consists of a series of heated plates or platens accuratel maoard. The platesare spaced apart accurately at a distance slightly greater than the finished thickness of the board because, fortunately, the board shrinks slightly after reachin a maximum thickness during the first viofient pulling reaction due to the sudden formation of steam. The facings are confined by the platens and the pressure, strange as this may Seem, is not great enough to cause excessive friction between the moving facings and the confining platens. The friction of the board sliding through the platens is further reduced by using polished platen surfaces. The spacing of the platens is regulated by means of screws 11 workin in brackets 12 attached to may be used to release sticking. The platens may be heated in any convenient ,way,"as by variousfluids. The fluids may be either liquid and gaseous, such the platens. ese

the board in case of combustion. In my as steam, air, gases of combustion, oil, water, molten salts and metals. Electricity may also be used.

As the reen board is rapidly heated to above the boiling point of water, the moisture in the mix is volatilized and escapes through the edges of the board, at the same time pressing the facings against the platens. If the dough-like mix is of the correct composition and consistency it puffs without appreciably blowing out at the edges, and does not collapze after the steam has escaped. After the large part of the steam escapes, the board has set and is hard enough to handle. It may now be trimmed and cut to length and given further treatments but I prefer to have the board pass directly through a heat treat/er before cutting to length. The board, if only puffed enough to set the porous structure, although hard, has alow water and moisture resistance and must be heat treated to become resistant. By removing residual moisture in the porous structure it becomes highly resistant to moisture provided that the correct ingredients are used in the mix.

Before assing into the heat treater I prefer to sid e trim the hot freshly set board with side cutting saws 13. These saws are preferably carborundum disks running at .high speed. The board is cut wider than the finished dimension to allow for shrinkage during the heat-treating operation.

The heat treater 9 referably is essentially an insulated tunnel through which the puffed board passes. The board may be untrimmed or side trimmed and is subjected to a predetermined temperature for a definite length of time to secure the proper moisture or water resistance. The board should be subjected toa temperature of about 210 C. or more for about 20 minutes or more. This insuressatisfactory results for a board. The heating should be long enough to penetrate through the board and therefore depends on the thickness. The length of time of heating at about 210 C. or more and the upper temperature is limited by the danger of discoloring the facings due to scorching. While any suitable method of heat treating may be used I prefer using hot gases, especially hot gases of continuous heat treater, both surfaces of the wall board are directly exposed to the hot gases as shown in Fig. 3. The trimmed edges expose the porous structure, thus allowing the moisture, which 1s I driven off by the high temperature, to cs cape easily. I prefer to have the gases pass over the board at a high velocity in a direction opposite to the travel of the board as indicated in Fig. 1, so that the hottest gases come in contact with the hottest portion of the board. The board may be supported on 1 rollers in the heat treater but I have found that the friction of the board sliding on stationary cross-bars 14, such as pipe, is insignificant.

The gases of combustion may be obtained from any suitable fuel, such as coal, coke, gas, or oil. The products of combustion from coal have to be filtered or settled to remove the soot before using. The gases of combustion from completely burned oil have given excellent results though the moisture content is high due to the combustion of hydrocarbons. However, condensation of this moisture has not been experienced nor has the humidity been too high for proper drying. This high moisture content may even be of value in preventing undue shrinkage or charring of the facings.

While the grates may also be used to heat the platens of the pufiing apparatus 8, I prefer to pass the gases of fuel through a heat absorber, whereby a por tion of the heat is used to heat a secondary fluid which can be used to heat suitable platens. In my prefcrred embodiment the gases of combustion from an oil burner are used to vaporize water in a boiler 15, the steam being led to and from the puffing platens by means of pipes 16 and 17. The hot gases of combustion from the boiler, at a temperature of about 250 to 300 C. are conducted by means of the insulated pipe 18 to a blower 19. These hot gases are illcreased in volume but cooled somewhat by partially cooled gases from the heat treater 9 through pipe 20 as explained hereinafter. The above gases of combustion are not of suflicient volume in all cases and may be too hot to secure eflicient and uniform heating in the heat treater and in such cases the above method of dilution is used. Control dampers 21 and 22 may be used to regulate the amount of dilution and the total volume of gases delivered-to the heat treater. The gases from the blower enter the heat-treater through inlets 23 at the board discharge end and pass along both surfaces of the board in chamber 24 as hereinbefore explained,

At the farther end of the tunnel, at the point of entrance of the board the gases are reversed in direction and are led back through ducts 25 and 26 parallel to the board surface to the point offirst entrance and then vinto pipe 20 andback to the fan. This duct may be formed by sheet iron partitions 27 and 28, as shown in Fig. 3. The heat treater may well be two or three time; as long as the pufiing apparatus. The hot gases returning act as 'a hot insulating medium for the hotter gases next to the board and thereby contribute to the efficiohcy of the operation. The sheet iron or other metal partitions 27 and 28 also radiate heat to the board surface. At the turning point of the gas stream a vent 29 is cut into the hcut treutcr tunnel to allow combuttion from the burned escape of the surplus .gas whichcarries with it the moisture removed from the board in of moisturefrom the board, providing the apparatus is free from leaks.

After the board leaves the heat treater 9 it passes through the pull rolls 10. The puffed and hardened porous mix is rigid after the heat treating and enough pressure may be exerted on the board without injury toit by the pull rollsso that these rolls can pull the board through the puffing apparatus 8, trimming saws 13, and heat treater 9, when the apparatus is working normally. This result I consider a surprising feature of my method and apparatus. The pul rolls 10 are preferably coated with an elas ic covering, such as rubber, to increase the friction and decrease the pressure due to increased area of contact. This area of contact may be further increased by increasing the diameter of the rolls. The finished board comes from the .pull rolls and is of the correct width and needs only to be cut to the desired lengths. This operation may be carried out by a cutter 30, which may be one of a number of such devices available. Theboards are then ready for stacking or shipment.

An illustration of the operation of the method in commercial practice may be stated as follows: Starting with an intumescent dough or plastic preferably composed essentially of one part of ahigh viscosity sodium silicate, which may bedolomitic in character and about 95% of which would pass through a 200 mesh screen, with less than 1% of a soap forming acid, as oleic acid, and starting with chipboard liners .037 thick, and of normal moisture content'and with the press rolls 4 adjusted to yield a finished board thick, the time of transit through the apparatus is about 35 minutes, of which about 11 minutes are used inpassing the material through the pufling apparatus and most of the remainder is used in the heat treating apparatus. This assumes a temperature-of 120 C. to 170 C. forsteam in the platens of the putting or intumescing ap'paratusand antemp'erature of about 210C. for the -flue gases within the inner chamber of the heat treatel. The foreand I amaware that be. made from these going is but illustrative, radical departures can avalues both with respectto the character of the raw material used and with respect to the tinieand temperatures of treatment. Thefinished product, say a wallboard thick, is strong and rigid, islight in weight,

* is a poor conductor of. heat because of its highly porous and cellular structure, is fire retardent, has no tendency to warp and is extremely resistant to the. action of moisture.

two parts of finely ground limestone,

It can be nailed to thestudding' of a building and there can be painted, or otherwise decorated, and it can, be used in many other relations where its water resisting characteristics, its lightness, strength or thermal resistance are of advantage.

.In some instances, I have found it desirable to make a board or panel with the liner omitted from one or both faces. Such a product can be made in the machine above described by the simple expedient of substituting in place of'paper liners 5 and 6 between which to form and puff the plastic mass, lining material such as heavily oiled paper to which the alkali silicate or other intumescent binder will not readily adhere. Such covering sheets can be unwound from reels, just as paper liners are unwound, and throughout the process of puffing and subsequent heat treatment will serve in the same way as paper liners, and at the tail end of the machine before the board is cut into commercial lengths these wax paper liners can be stripped off at or beyond the pulling rolls 10 and wound up on reels 31 and 32 for reuse. Thin burnished strip steel, or other metal, can similar-1y be used as a temporary covering for one or bothsides of the mineral core or sheet, being unwound from reels as the paper liner is unwound and being wound up on reels 81 and 32, or if desired, can pass back as an endless band to the plastic shaping rolls 4.

I claim:

1. In a machine of the character described shaping an intumescent plastic between I the combination of means for continuously covering sheets and means for continuously passing the product so formed between platens heated to intumesce said plastic,

2. In a machine of the character described means for continuously shaping an intumescent plastic between covering sheets, heated platens bet-ween which the product so formed may pass and means for continuously pulling said product between said platens.

3. In a machine of the character described the combination of means for continuously shaping a plastic between covering sheets,

platens between which the product so formed.

may pass said platens being heated to a temperature in excess of 120 (1., heating means beyond said platens for increasing the temperature of the material under treatment and means for continuously moving said product through the platens, substantially as described.

4. In a-maehi'ne of the character described the combination of means for shaping an intumescent plastic into a thin layer between continuous covering sheets of paper and means for continuously passing the product so formed between platens heated to a temperature suthcient to intumesce said plastic.

. 5. In a machine ofthe character described a which the product the combination of means for s hap an intumescent plastic into a thin layer etween continuous covering sheets, platens between so formed may pass, said platens being heated to a tem erature adequate to quickly intumesce sai plastic, and means beyond said platens for continuously pulling the material under. treatment through said platens.

6. In a machine of the character described the combination of means for continuously shaping an intumescent plastic between continuous covering sheets of paper, fluid heated platens between which the products so formed may pass, said platens being heated hot enough to intumesce said plastic, heat treating apparatus beyond said platens for raising the temperature of the material still higher and means beyond said heat treatin apparatus and frictionally engaging said cover sheets to continuously pull the material under treatment through the platens and through the heat treating apparatus.

7. In a machine of the character described the combination of means for shaping a plastic between continuous covering sheets, platens between which the product so formed passes, said platens being heated to a temperature in excess of 120 C, heating means beyond said platens for increasing the temperature of the material under treatment to a temperature in excess of 210 (1., and

' means for continuously pulling said product through the platens and heat treating apparatus. In an apparatus of the character described, means for shaping an'intumescent plastic between covering sheets, platens between which the product so formed may be heated to a temperature in excess of 120 C.' and means for subsequently subjecting sai product to heated gases at a higher tempenaure. v In an apparatus of the character described means for shaping an intumescent plastic in a flat layer between covering sheets of aper, means for heating the product so ormed to quickly intumesce the plastic and means into which said productwhil'e stlll hot can be introduced for further heat {)reattment with circulating products of comus ion.

' 10. In an apparatus of the character described the combination of means for form-.

mg a thin layer of intumescent plastic between contlnuous covering sheets, steam heated platens between which the product so formed may pass,. heat treating apparatus beyond said platens for heating said product to a higher temperature in circulating prodnets of combustion, and a boiler o eratively connectcd'fo'r delivering steam to sald I and products of combustion to sand heat tre'atinlgI apparatus.

11. a machine of the character deplatens vproducts passed therethrou comprising a puffed mixture pair of rolls beyond said heat treatin apparatus for pulling said product throng the platens andthrough the heat treating apparatus and-means for delivering steam to said platens vand for delivering products of combustion to said heat treating apparatus for direct contact with the product continuously passing therethrough.

12. In an apparatus for making wallboard, a heat treater having partment through which the wallboard may be passed, means for producing products of combustion and means for blowing ,said products through said compartment to raise said wallboard to a higher temperature.

13. In an apparatus for the heat treatment of wallboard, the combination ota central compartment throughwhich wall board aper covering sheets,

a central comcompartment, and for receiving products of combustion from said chambers.

14. In a machine for making wallboard the combinationof means for shaping in tumescent plastic into a continuous covering sheets of paper, means for continuously passing the product so formed between platens heated to a temperature suflicient to intumesce said plastic, and, means interposed between the shaping means and the platens for removin excess plastic from the edge of the continuously traveling layer. v

15. In a machine for making wallboard in continuous lengths and with a la er of mixed alkali silicate and filler pufila d by heat and held between paper liners com rising in combination heating platens, eat treating apparatus beyond said platens, and pulling rolls for moving the product continuously through the platens and heat treating apparatus.

16. In an apparatus for making wallboard comprising a puffed mixture of alkali sili-.

thin layer between from said absorber to said heat treating ap- I paratus tocomplete the heat treatment 0 g 17. An apparatus for makin wallboard o alkali siliiao the product so formed between platens cate and filler, the combination of pufling apparatus, a heat treating apparatus, a heat absorber having an oil burner, means for delivering heated fluid from said absorber to said pufling apparatus to heat wallboard passing therethrough, and means for delivering hot waste gases of combustion from said oil burner into direct contact with said wallboard in said heat treating apparatus.

18. A machine for making wallboard comprising a puffed mixture of alkali silicate and filler, comprising in combination means for rolling adoughlike mix of filler and alkali silicate between two continuous facings,

' means for puiiingsaid doughlike mix, means for continuously trimming the edges of said pufi'ed mix and faces, means for heat treating the board so trimmed, means for pulling said board through said pufling means, said trimming means and said heat treating apparatus, and a heat absorber operativelyconnected to supply hot fluid to said puffing means and hot waste gases of combustion to said heat treating m'eans.

19. An apparatus for continuously heat treating wallboard by the direct action of hot gases of combustion on puffed faces of said board comprisin in com ination a compartment through w ich wallboard can be passed in a continuous length, a blower delivering hot gases to said compartment in a direction opposite to that, of the moving board, said compartment having an opening.

for the discharge of excess gases into the atmosphere, and chambers adjacent to said compartment for reducing the radiation of heat therefrom, said chambers being connected to deliver gases back to the blower for admixture with fresh gases of combustion and recirculation through said compartment.

20. The method of making wallboard which comprises continuously shaping an intumescent plastic between covering sheets and continuously passing the product so formed between platens spaced from each other a distance slightly greater than the thickness of the finished product heated to a temperature suflicient to intumesce said plastic.

' 21. The method of making wallboard which comprises continuously shaping an im tumescent plastic and continuously pulllling eated to a temperature sufficient to intumesce said plastic.

22." The method of making wallboard which comprises rolling an intumescent plastie into intimate contact with covering sheets of paper and continuously pulling the product'so formed between platens heated to a tem erature of about 120 C. or higher to quic l intumesce said plastic.

23.' he method of making wallboard platens which comprises continuously shaping an intumescent plastic between covering sheets of paper and progressively advancing the prodnot so formed between platens heated to a temperature of 120 C. or higher to quickly intumesce said plastic and then into a treating chamber maintained at a higher temperature, substantially as described.

24:- The method of making wallboard which comprises shaping an intumescent plastlc between covering sheets and then 1nenough to quickly intumesce the plastic and then immediately through a hotter chamber for removal of moisture from the intumesced plastic.

26. The method which comprises rolling an intumescent plastic into a thin layer between covering sheets of paper and continuously passing the product so formed between platens heated to a temperature sulfic1ent to quickly intumesce said plastic and subjecting the material while still hot to the drying action of hot 27. The method board comprising a mixture of alkali silicate and filler, which comprises passing said wallboard in a continuing length through. a compartment and there subjecting it to hot gases of combustion, said gases flowing at a high velocity in a directlgOIl opposite to that in which the wall board moves. v

28. The method of heat treating wallboard of continuing length which comprises passing said board through a compartment, blowing hot gases of combustion into said compartment in the opposite direction, drawing off a fraction of the gases passed through the compartment and redelivering the remainder into said compartment admixed with additional hot products.

29. The method of making wallboard gases.

of heat treating wall' Ill comprising a puffing mixture of alkali silicate and filler, said method comprising puliing said mixture by means of steam heated platens, and thereafter heat treating said board with hot waste gases of combustion in direct contact therewith, the steam for the and the waste gases being supplied from a fluid fired boiler.

30. The step in the making of wallboard comprising a mixture of alkali silicate and filler, which consistsiin trimming said board after it has acquired a permanent set in a preliminary heat treating operation but before being permanently hardened in a final heat treatment.

31. The step in the method of making wallboard comprising a mixture of alkali silicate and filler puffed by heat, which comprises edge trimming said board after the pufiing operation and before final heat treating, said trimming being to a Width greater than the desired finished dimension to allow for shrinkage during the subsequent heat treatment.

32. As a step in the manufacture of wallboard comprising a thermally puffed mixture of alkali silicate and filler which comprises continuously edge trimming the .hot board while it passes continuously from the putting to the final heat treating apparatus,

that trimming being to a width greater than of about 210 the width of the finished board to allow for 20 contraction during final heat treatment.

33. The method of heat treating wallboard comprising a pufi'ed mixture of alkali silicate and filler, which comprises subjecting said board to hotgases at a temperature C. or more while said board is still hot from a preliminary puffing operation.

34. The method of heat treating wall-4 board comprising a puffed mixture of alkali silicate and filler which comprises subjecting said,board while still hot from a preliminary putfi'ng operation to the hot gases of combustion of a liquid fuel, said gases being at a temperature of about 210 C. or more.

In testimony whereof I aflix my signature.

KEMPER SLIDELL.

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