US2697249A

US2697249A - Method and apparatus for the manufacture of particulate wax and wax objects

Info

Publication number: US2697249A
Application number: US167216A
Authority: US
Inventors: Jr Richard Stockwell Bettes; Jr Vernon Keenan; Radkins Andrew Peter
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1950-06-09
Filing date: 1950-06-09
Publication date: 1954-12-21
Anticipated expiration: 1971-12-21

Description

1954 BETTES, JR.. EIAL 2,697,249

8. METHOD AND APPARATUS FOR THE MANUFACTURE OF PARTICULATEI WAX AND WAX OBJECTS Filed June 9, 1950 3 Sheets-Sheet 1 l6 Wax 7 23 0 2/ 2/ Air 4/! METER/N6 F 1 5: FEED HOPPER INVENTORS:

R/chard S. BeffeqJr: DIE-FORMIN6 Vernon Keenan,Jr: PRESS Andrew pgwins y M R. s. BETTES JR.. ETAL 2,697,249 METHOD AND ARATUS FOR THE MANUFACTURE ATE WAX-AND WAX OBJECTS 3 Sheets-Sheet 2 OF PARTI Filed June 9, 1950 INVENTORS:- Richard S. BeffesJr, Vernon Keenan, J1. Andrew P. R ins duazf I 4 OALMEY 1954 R. s. BETTES, JR, ETAL 2,697,249

METHOD AND APPARATUS FOR THE MANUFACTURE OF PARTICULATE WAX AND WAX OBJECTS DRUM SPEED In v m N o o o c o c 0' Q 'NIW 83d 1.4 OS HIId'SS'h-JJVH NOI.LVIJL:IIGI IOS Lq INVENTORY-'- R/chard S. BeffegJr w gegn on P/fgeg my, Jr.-

.. x i n rew a ms Rig fim MK arrzwsv United States Patent() METHOD AND APPARATUS FOR THE MANUFAC- OF PARTICULATE WAX AND WAX OB- Richard Stockwell Bettes, Jr., and Vernon Keenan, Jr.,

Chicago, Ill., and Andrew Peter Radkins, West LaFayette, Ind., assignors to Standard Oil Company, Chicago, 111., a corporation of Indiana Application June 9, 1950, Serial No. 167,216 14 Claims. (Cl. 18-4) This invention relates to a method and apparatus for continuously producing substantially uniform size particulate paraffin wax and to the manufacture of solid Iiii/ax objects by the die forming of the particulate parafn wax.

An object of this invention is to provide a novel method and apparatus whereby molten wax may be rapidly and efiiciently transformed into uniform size particulate wax solids. A further object is to provide a novel method and apparatus whereby molten Wax may be transformed into uniform size wax cakes or the like in a continuous and substantially automatic manner. These and additional objects will be apparent from the following specification and claims.

It is the customary practice in many wax plants to form refined wax into large rectangular cakes to facilitate shipping and storage; smaller cakes on the order of one-quarter of a pound are sold commercially for domestic use. These cakes are at the present time ordinarily made by pouring molten wax into molds. This casting technique is a batch process comprising distinct steps and as such requires considerable labor to transfer material from step to step. A definite problem with the casting technique as applied to parafiin wax resides in the very poor heat conductivity of paraflin wax. Such a method of operation involves the transfer of heat through a layer of solid wax which steadily increases in thickness and resistance to heat flow; the solidification of liquid wax is therefore slow and inefiicient. We have invented a method whereby wax may be rapidly solidified and formed into rectangular cakes or the like with none of these disadvantages. Flexibility of the casting process is also poor in that a change in rate of production may only be achieved by changing the number of molds or varying the frequency of casting. Casting in conveyed molds could conceivably render the above technique continuous but the inherent shortcomings such as the long cooling period would not be eliminated.

In an effort to facilitate the manufacture of uniform size solid wax cakes attempts have been made to continuously produce them by extrusion but the physical characteristics of paratfin wax which cause it to retain locked up stresses arising from deformations during extrusion have resulted in products of poor surface finish and fibrous structure as well as being subject to undesirable distortion in the event of storage at summer temperatures. It would appear that subjecting such cakes to summer temperatures in the range of from about 85 to about 100 F. releases the internal stresses which renders the normally brittle wax plastic and allows the cakes to distort.

We have now developed a continuous process whereby molten wax may be cooled to a plastic or semi-solid condition, finely comminuted and pressed into wax cakes which are in every respect equal or superior to the cast product. Our process is particularly adaptable to variation in the rate of manufacture without change in equip ment requirements.

Wax has been formed into particulate solids by various means, one of the best known of these being the rotating drum chiller with cooperating scraper blade. In that process molten wax, at a temperature somewhat above its melting point, is caused to solidify and adhere in a substantially uniform film about the periphery of a rorating drum chiller having a segment of its periphery immersed in a bath of liquid paraffin. It has been the practice when employing these drum chillers to circulate within the drum a coolant of sufiiciently low temperature to impart brittleness to the adhexing wax film. Thus, the wax breaks into various size pieces at the scraper blade element which is in continuous contact with the rotating drum across its entire length. The extrusion of non-uniform wax fragments formed in the above described method into wax cakes by continuous screw extrusion has been described in the prior art but because the fragments were too large and non-uniform and because of the inherent problems encountered with extrusion the process has never achieved commercial acceptance.

While the above method of obtaining flaked wax is advantageous in that it offers a method for rapidly cooling parafiin wax it is unsatisfactory because, in addition to giving relatively large non-uniform fragments of wax, refrigeration is often required to cool the water or other fluid circulated within the drum to a temperature which will permit fragmentation or flaking of the wax at the scraper blade. Thus, it would be greatly advantageous if this refrigeration could be eliminated and particularly if ordinary tap Water, at temperatures encountered the year around, could be employed. It has been found, however, that when a coolant such as non-refrigerated tap water is employed which is not of sufiiciently low temperature to cool the wax adhering to the drum to a point at which it will be flaked upon contact with the scraper, the wax will ride over the scraper in a more or less continuous strip of plastic or semi-solid wax.

Throughout the specification and the claims which follow it is intended that the terms semi-solid and plastic, when referring to the wax film or to the particulate wax solids, shall be synonomous and that they shall be descriptive of wax in general and parafiin wax in particular which is sufiiciently pliable to ride over the scraper blade in a substantially continuous ribbon or film. A parafiin wax melting at 122 to 124 P. will be in this condition at a temperature in the range of from about 30 F. to about 40 F. below its melting point. This range depends upon the melting point of the Wax, hence for a higher melting wax it would be somewhat higher and may be readily ascertained for any individual wax. Within these ranges the normally brittle nature of wax is supplanted by the plastic or semi-solid. The comminution of wax in this plastic condition to obtain finely-divided wax particles of substantially uniform size was an extremely perplexing problem.

Briefly described, our invention comprises the continuouscooling and transformation of molten wax into a film of semi-solid or plastic wax by immersing a segment of the periphery of a rotating drum cooler in a pan of molten wax, stripping a continuous film of plastic wax from the surface of the drum, introducing the film of plastic wax to a novel cutting device wherein the semi-solid wax is uniformly comminuted, cooling the uniformly particulate wax with a cooling gas in order to prevent adherence between the particles and to the equipment and die forming the particulate solids into solid cakes or the like.

One of the principal advantages of our novel process is that rapid cooling of molten paraffin by solidifying it in film thickness is obtained and since this film of wax Ican not-be scraped, abraded or crushed because of its lack of structural strength and its viscous nature it is necessary that it be cut. While the thickness of the film of wax which is continuously removed from the cooling drum-will vary somewhat with the speed of the rotation of the drum, the temperature of the cooling water and other factors, a thickness of the order of .010 to .040 inch will ordinarily be encountered. Since the film of wax is quite thin, cutting is necessary only in the direction substantially perpendicular to the wax film. Our novel cutting device comprises two opposed counterrotating intermeshing multi-tooth cutters. Each rotatable cutteritself comprises a plurality of multi-tooth blades juxtaposed on a rotatable shaft and positioned so that they coact with the blades of the opposing cutter to com- ,minute the wax film.

In the accompanying drawings:

within that range Fig. 1 is a diagrammatic representation of our process showing the relative positions of equipment.

Figs. 2a, 2b and represent some alternative cutter blade designs, Fig. 2a being the blade design embodied in the cutters of rigs. 3 and 4.

Fig. 3 is a partial plan view of the cutting device shown diagrammatically in Fig. 1.

Fig. 4 is a sectional view of the cutters shown in Fig. 3 taken along lines 4-4.

Fig. 5 is a graph showing the relation of the capacity of the cooling drum and character of the wax film to the drum speed, cooling water temperature and cooling water flow rate.

Referring to Fig. 1 a. paraffin wax having a melting point of 122 to 124 F. is introduced at a temperature of from about to 75 above its melting point via line 10 into wax tank 11. It is recommended that the wax be at a temperature sufficiently above its melting point to minimize undesired caking of the wax. The five foot diameter drum 12 having a length of twelve feet is rotatably positioned on supports 13. The drum is rotated at from about 2 to about 10 revolutions per minute (by means not shown) in such a manner as to permit the continuous immersion of a segment of the periphery of the drum in the molten wax- The cooling drum employed in our process is of standard construction and is well known to the art and while we prefer to use this means of obtaining a substantially continuous film of plastic wax any other method whereby such a film is produced may be satisfactorily employed.

A typical example of the type drum which is suitable for our process is shown in U. S. 1,361,346. In general all of the mechanical details which are essential to the satisfactory operation of this drum are well known to the art, hence no detailed description of this apparatus is necessary. We prefer to direct a continuous spray of coolant against the top of the inside of the drum which results in a continuous falling film of coolant along the drum walls. The coolant is continuously removed from the bottom of the drum by a suction pump.

As drum 12 is rotated through the molten wax a continuous film of wax 22 is formed on the outer surface of the drum which is at a temperature substantially below the solidification point of the wax. We prefer that the film coming olf of the drum and entering the cutters be within the range of from about to about F. below the melting point of the 122 to 124 F. wax. This temperature range embraces the so-called plastic range of the 122 to 124 F. wax and it is only that the cutters operate efficiently; below about 82 F. the film to be brittle while above about 94 F. it is too soft. Whereas the plastic range varies according to the melting point of the wax employed so also does the temperature of the wax film entering the cutters vary with the speed of rotation of the cooling drum, the temperature of the coolant and the rate of introduction of the coolant. These phenomena will be hereinafter more fully described. As the drum rotates, the wax film 22 is continuously stripped off by scraper blade 15 which is in continuous contact with the outer surface of the rotatmg drum. The wax film 22 which is stripped from the drum by scraper blade 15 passes over the wax guide 16 cooperatively positioned below the scraper blade in such a manner as to guide the wax film to a point 17 at the intersection of the outer circumferences of the circles formed by the rotation of the teeth on

cutters

18 and 19. It is essential that wax guide 16 be at a temperature low enough to prevent sticking of the wax film as it is directed to the cutters. Additional cooling may be obtained by any suitable means such as a stream of cooled air on the underside of the guide or by employmg a hollow guide and internally cooling by the same rnedium that cools the drum 12. The wax film passes into the cutting device 23 and is comminuted by the rotation of

cutters

18 and 19 toward the wax film.

For satisfactory comminuation it is essential that the wax film approaching the cutters be within the plastic range yet not too warm. Generally, achieving a film temperature in this range will not be difiicult, since with solidification of the wax as the drum turns the wax temperature will fall rapidly to about this temperature. However, should the drum speed be too low or the cooling rate too high the film may be cooled to below about 82 F., become brittle, and as a result break mto non-uniform fragments at the scraper blade coming off the drum tends or in the cutters. On the other hand if these conditions are reversed the film becomes too soft, is not properly comminuted and tends to foul the cutters. Adjustment of both drum speed and cooling water flow rate are therefore necessary for control of film temperature as well as production capacity.

The particulate wax solids formed by the cutting of wax film 22 fall through a collecting chute 20 and into the metering and feed hopper 24. Proper passage of the wax particles through the chute and into the metering and feed hopper demands that the particle temperature (at least on the surface of each particle) be at a lower temperature than that at which the wax strip enters the cutter. A temperature between about and F. is preferred. As these wax solids descend from the cutting device they are contacted with an inert cooling gas, preferably air, introduced at suitable points 21in chute 20. This cooling gas may be directed at the falling wax by any suitable method, the purpose of contacting this wax being to lower its temperature and thereby lessen its tackiness in order to substantially prevent the adherence of the more or less semi-solid particles with one another and to the sides of the equipment. It is advantageous under certain circumstances, rather than merely contacting with a cooling gas, to provide an air conditioned space in which the particles fall; this is particularly desirable when the air in the vicinity contains substantial amounts of impurities which destroy the quality of the wax. From the hopper 24 the wax particles are automatically fed in metered amounts to the continuous die-forming press 25. While both the metering and feed hopper and die-forming press are commercially available devices requiring no detailed description, they will be referred to briefly hereinafter.

For each inlet temperature of coolant the wax solidification rate varies linearly with the speed of the drum, the rate of coolant flow being fixed. Fig. 5 illustrates the adaptability of the drum cooler to solidification of a parahin wax melting at 122 to 124 F. at various coolant temperatures. The short lines perpendicular to the inlet cooling water temperature lines indicate the limits beyond which the wax film is either too soft or too brittle for proper comminution. Since the temperatures of the cooling water fall within the year-around tap-water range it is apparent that it is only necessary to adjust the speed of rotation of the drum in accordance with coolant temperature and flow rate in order to maintain a wax film which is suitable for comminution in our apparatus. The availability of considerable heat permits the temperature of the coolant to be raised during winter months if it is found to cause embrittlement even at relatively high drum speeds and/ or low flow. rates.

Stainless steel is a desirable material of construction for the periphery of the cooling drum because it is necessary that it have a high quality smooth finish since the scraper blade will bear against its entire surface. The pressure of the scraper blade against the drum need not be great for if the surface finish is good the wax film can easily be stripped therefrom but it is well to be able to adjust the pressure if for any reason it is found necessary to do so. Other metals having the characteristics described, such as chrome plated steel, galvanized iron or the like may also be used. The scraper blade may be constructed of any of the above metals, preferably one of a somewhat softer nature in order to avoid wear on the drum surface.

The blade shown in Fig. 2a corresponds to those embodied in the cutters shown in Figs. 3 and 4. These blades are formed from sheet metal by a suitable means such as stamping and should not have a thickness greater than about 0.065 inch. All of the blades embodied in

cutters

18 and 19 are identical in physical dimensions except for possible slight variations in thickness. Each blade on the cutter differs however, from those juxtaposed thereto in the position of the three smaller holes which are bored about the center hole of the blade to permit its alignment on guide rods 28. The manner in which these holes are positioned will be hereinafter more fully described. For the purpose of this example the diameter of each blade is 8 inches.

In Fig. 4 the cutters are seen from an end view and while only six blades on each cutter are visible, reference to Fig. 3 indicates that there are a plurality of blades in alignment with each of the visible blades. Thus, there are 36 axial rows of teeth about each rotatable cutter, the teeth in each axial row being separated by the thickness of five blades. This distance between teeth in an axial row is designated as R in Fig. 3. Because of slight variations in sheet metal thickness it is possible in actual construction that the distance R will not remain constant for the entire length of the cutter, so that in a cutter of substantial length, e. g. 12 feet, the blades such as 38 and 41, 39 and 42, 40 and 43, etc. respectively as shown in Fig. 3 tend not to be in the same vertical plane as in Fig. 3 and the likelihood of contact between cutters is increased. Taking into consideration such an occurrence the cutters are designed .so that the axial rows of teeth may intermesh; thus, if it were found that the cutters shown in Figs. 3 and 4 were striking one another it would be necessary only to disconnect

gearing

44 and 45 which fix the relative movements of the two cutters, rotate either cutter 5 while holding the other cutter fixed and then to reconnect the gearing. It may be desirable to set the cutters in this manner originally to remove any possibility of contact.

The opposing cutters need only intermesh a distance equal to the thickness of the wax film passing between them and they must intermesh without striking. Based on these principles, the number and shape of teeth may be varied considerably as designs in Figs. 2a, 2b and 2c. process to have as many teeth on in order to have the number of film per linear inch substantially maximum.

Referring to Fig. 4, the

blades

29, 30, 31, 32, 33 and 34 comprise what is referred to herein as a pattern cycle and it may be seen from Fig. 3 that this pattern cycle is repeated many times on each cutter. The linear distance between the axial rows of teeth formed by the tips or apexes of the teeth an important factor in cutter design. The distance should be about /1 inch to an inch preferably about 0.70 inch regardless of the diameter of the cutters or the number of teeth per blade. It should not be substantially greater than about one inch because of the attending increase in particle size at any given angular velocity nor may it be substantially less than /2 inch because of the necessity for intermeshing of opposing rows of teeth without contact. This distance is indicated in Fig. 4 as Y.

Set forth below are mathematical formulae which will enable one skilled in the art to design a cutter suited It is preferred in our the cutters as possible teeth striking the wax to his needs.

(1) =0.70 inch (approximate distance) or N=4.488D

N (2) I ;=4 or a larger integer wherein D=cutter diameter N =number of axial rows of teeth per cutter n=number of teeth per blade =number of blades per pattern cycle Since the number of rows of teeth per cutter must be numerically divisible by a whole number in order to obtain the number of teeth per blade the distance between rows of teeth will of course vary slightly from 0.70 inch in order to give this desired result. The distance between teeth in an axial row is important in that ribbons of wax will result if these teeth are too close together. If fewer than four blades are positioned be tween the teeth in an axial row the comminution is not entirely satisfactory. Following is an example of a design calculation for the 8 inch diameter cutters shown in the drawings.

EXAMPLE -=0 70 (approximate distance) N =35.904- or 36 (taking nearest whole number divisible by a suitable I, e. g. 6)

shown in the alternative blade in repeating pattern cycles, is

Checking back in the original formula and changing 0.70 to Y we determine the actual distance between teeth:

Y=.6981 inch (actual distance) n=6 teeth per blade The 8 inch diameter cutter described herein has six teeth per pattern cycle and 36 axial rows of teeth on the cutter, thus the rows of teeth are separated by an angle of 10. At 10 the actual distance between teeth as shown in the above example is 0.6981 inch. While we find that the use of the 0.70 inch as the distance between rows enables us to design our cutters for a substantially maximum number of teeth for any diameter cutter this distance can be varied slightly within the limits set forth but we prefer a distance above about 0.65 in order to eliminate any danger of contact between opposing cutters and at the same time maintain excellent particulation. It is feasible to cut 8 inch diameter blades having eight teeth which would then be positioned on the shaft so that the pattern cycle would have five teeth 9 apart and the entire cutter would have 40 rows of teeth instead of 36 which would be an increase of 11.1% in number of rows. Since the pattern cycle would then have five teeth rather than six there would be 20% more teeth per row which gives an overall increase in number of teeth amounting to 33%. With that design, rather than 0.6981 inch, the distance between rows would be 0.6033 inch. It is ordinarily unnecessary to approach the absolute maximum number of teeth and minimum distance because the distance of about 0.70 inch between rows of teeth gives a very finely comminuted wax. In any event the slightly increased particle size encountered y not having the maximum number of teeth can be readily offset by an increase in the angular velocity of the cutter.

Guide rods 28 fix the position of the cutter blades relative to one another. The three guide holes on each successive blade in a pattern cycle are 10 removed from those on the adjoining blades. Thus the blades are positioned at six different relative locations about the center hole corresponding to the angle at which each blade in a pattern cycle is positioned on guide rods 28. Fig. 2a indicates with respect to one hole how all three holes are bored in successive blades. The cutter blades may be permanently affixed to the

rotatable shafts

26 and 7 by various means such as a key running the length of each shaft positionable in slots in the cutter blades as shown in Fig. 2a or by passing the guide rods through flanges pinned to the shafts at each end of the plurality of cutter blades. The blade shown in Fig. 2c does not have the three holes for the guide rods as do those in Figs. 2a and 2b. The slot 37 is cut in each blade of a pattern cycle at a position 10 removed from its adjoining blades and serves the dual purpose of fixing the relative positions of the blades and permanently fixing the blades to the shaft. The geometrical pattern of the rows of teeth need not conform to the straight axial pattern shown in the drawings but may comprise a helical design or the like as long as the requirements for intermeshing, as set forth above, are fulfilled.

Whereas the drawings and description hereinbefore set forth relate to a preferred embodiment wherein the blades on opposing shafts form axial rows of teeth which intermesh with the rows of teeth on opposing cutters, it is also possible to employ cutter blades on the opposing shafts which are in alternating vertical planes and which may have substantially more teeth. When the teeth of opposing cutters do not intermesh but coact in an altermating manner so that each blade on either cutter will extend approximately the thickness of the Wax film between two blades on the opposing cutter the need for fixed

connection

44 and 45 between cutters is eliminated because contact between the teeth of opposing cutters is impossible; the geared connection may be employed, however, rather than having a driving means on each shaft.

In addition to the modification in relative positions of the opposing cutter blades the shape of the teeth on the blades may also be varied as is shown in Figs. 2b and 2c. The principle on which the cutters operate is that the teeth should cut into the wax ribbon approximately perpendicularly from each side, thus it is advantageous to employ blades having a sli ht positive rake as shown in Figs. 2b and 2c in order to obtain this desired result. While we have described the cutters as being produced from stamped sheet metal blades it is possible, although considerably less economical, to affix tooth-like inserts about the rotatable shafts in order to obtain the same tooth configuration.

it is ordinarily satisfactory if each cutter blade positioned on the rotatable shafts is positioned flush against its adjacent blades but it is desirable under certain conditions to position spacer elements between each adjacent blade, e. g. where extremely thin cutter blades are employed or when employing the alternating blade arrangement described above wherein the teeth of opposing cutters do not intermesh and it is necessary to have each blade on both cutters extend between two blades on the opposing cutter.

Proper positioning of the film guide is extremely important. Satisfactory comminution is dependent to a great extent upon both cutters sharing equally in the cutting. Thus, they will be cutting substantially simultaneously from both sides of film and this action will serve to hold the leading edge of the film at the point of intersection of the teeth. Should the guide or the wax itself be displaced in the direction of one of the cutters, that cutter will exert a beating action on the wax film and a preponderance of large ribbons will result. Fig. 4 clearly shows the relation of the wax guide in, wax film 22 and cutters 1% and 19 to one another.

The wax particles are die formed in automatic presses of the plastics preform type. In general, the tooling on these presses consists of a stationary die cavity of dimensions equal to those of the fiat surface of the piece to be formed, a movable upper punch which applies pressure to the material in the die, and a movable lower punch which forms the bottom of the die cavity during pressing. Feeding is accomplished by means of a reciprocating feed hopper timed with the other movements of the press so that it can travel in over the empty die cavity, deposit a volumetrically controlled amount of granulated material and Withdraw to allow for pressing. In addition to automatic filling, the feeder serves to eject the finished piece which is carried to the top of the die cavity by the motion of the lower punch. The pressing cycle is completely automatic, and the necessary adjustments for controlling size and weight can readily be made. Both hydraulic and mechanical preform presses are available commercially.

o't only is it essential that the particulate wax produced be substantially uniform in size but it is also necessary that the particle size be held within certain limits. This limitation is established by two principal factors namely length of the stroke of the press and the appearance and physical characteristics of the finished cake.

Since each press is limited as to length of stroke, the total 1 depth of unpressed particulate solid necessary to form a cake of the desired thickness is limited thereby. The finer the wax is cut, the lower the depth of uncompressed solids. In addition the more finely divided wax yields more uniform structure and surface finish to the pressed cake. In order to classify the particulate wax according to size we have found that it is best described by reference to its bulk ratio. The bulk ratio of particulate wax is that figure which represents the ratio of a volume of unpressed wax to the volume of a solid cake produced by the unpressed wax. Since the volume of particulate wax will vary with settling, two volume measurements are ordinarily made on the unpressed wax: one immediately after pouring into a measuring vessel and another after forced settling caused by light tapping on the vessel has ceased. in table I below, the maximum figures relate to the volume measurement taken immediately and the minimum is ping.

that after light tap- Table I BULK RATIOS OF SAMPLES OF GRANULATED PARAFFIN WAX Drum Bulk Ratio Cutter Speed, R. P. M. Speed,

Max. Min.

It can be seen from above table that the bulk ratio varies substantially with cutter speed. It has also been found to vary with the speed of the wax film, i. e. increased wax film speed is accompanied by an increase in bulk ratio. lowever, this variation is considered slight and can readily be accommodated by increasing the speed of the cutters.

The degree of particulation necessary for process operation is primarily limited by the design of the press. Many presses suitable for this operation require that the bulk ratio of the material being handled be less than 3 /2. A maximum bulk ratio slightly higher than 3 /2 might be tolerated since the slight vibration of the feed mechanism tends to pack the material.

The shape of the die fixes two dimensions of the piece. The third dimension is controlled by the length of travel of the upper punch and depth of fill in the case of a mechanical press and by either length of travel of the upper punch and depth of fill or a combination of depth of fill and control of loading pressure in the hydraulic press. in both cases weight control is volumetric. While we have described the production of rectangular cakes it should be understood that objects of considerably different appearance such as novelty figures and the like may be continuously prepared by this method.

One difficulty which was encountered was the sticking of the wax to die surfaces. This was overcome by heating the punch faces sufficiently to maintain a film of liquid wax between punch and cake.

By this method of producing wax cakes it has been found that the weight of the cake can be held to within 112% of the desired amount. Since the weight of the cake is controlled by depth of fill of the die cavity, the mean weight of the cake, within the limits set forth above, can be set to any desired amount.

The appearance of the cakes-produced is excellent. They are considerable whiter than the cast cake, edges are sharp and the surface finish is smooth. The fact that fusion of particles is not complete results in a cake which, while sufficiently strong to withstand handling. packaging, storing and shipping, is more conveniently broken by the consumer when just a portion of the cake is desired. Scoring of the cakes for clean breaks is easily accomplished during the pressing operation.

in order to regulate the rate at which the particulate wax solids fall through the chute and enter the metering and feed hopper it may be desirable to introduce the air in the lower regions of the chute at such a velocity that the particulate wax is fluidized and has a net downward movement at a. rate considerably less than free falling wax or wax propelled rapidly from the teeth of the cutters. In this manner piling of the wax is substantially eliminated and the proper amount of wax for the die press can be continuously fed to the feed hopper.

The paraffin cakes so formed have shown surprisingly good storage ability under simulated summer conditions at 95 F. No distortion attributable to the compression of a mass of particles could be observed.

For certain novel purposes the particulate wax itself may be marketed without pressing it into cakes.

It will be understood that various changes and modifications may be made in our novel process andequipment without departing from the spirit thereof and while we have specifically described the process and apparatus with respect to parafiin wax it is adaptable for other waxes, both natural and synthetic. Materials such as soap, detergents, polyethylene and other organic or inorganic materials which do not decompose upon melting, do not readily sublime and which will form a substantially continuous film of readily comminutable solid can be processed in substantially the manner described. The foregoing description and the drawings are intended to be illustrative only and the invention is to be limited solely by the appended claims.

We claim:

1. The method of processing a material which passes through a plastic state while being transformed from liquid to solid, which method comprises producing a continuous moving film of said material in the pliable plastic state, guiding said plastic film to a device for cutting said film, cutting the moving film from opposite sides thereof While said film is in the pliable plastic state to produce particles of substantially uniform size and cooling said particles to prevent adherence between particles and to provide a free-flowing mass of particulate material suitable for die compressing.

2. The method of claim 1 wherein volumetrically measured quantities of the uniform particles produced by cutting the plastic film are compressed to form solid objects of substantially uniform weight and substantial freedom from internal stress.

3. The method of processing molten Wax to obtain solid objects substantially free from internal stresses which method comprises transforming the same into a continuous pliable plastic film, producing particulate wax of substantially uniform size from said film while in the pliable plastic state by cutting the same from opposite sides thereof and cooling said particles to prevent adherence between particles and to provide a free flowing mass of particulate wax suitable for die compressing.

4. The method of claim 3 wherein volumetrically measured quantities of the particulate wax are die-compressed to produce objects of uniform weight and substantial freedom from internal stress.

5. The method of converting molten wax into substantially uniform wax particles suitable for producing solid Wax masses substantially free from internal stresses and having a bulk ratio not greater than about 4 which method comprises passing the periphery of a cooled drum through a tank of molten wax to produce a continuous non-brittle plastic film of wax thereon having a thickness no greater than about .04, removing said non-brittle film from the periphery of said drum, comminuting said film into particulate wax while in the non-brittle plastic state by cutting the film from opposite sides thereof as it is removed from said drum and introducing cooled air into contact with the particulate wax to prevent adherence between particles and to provide a free-flowing, non-agglomerative mass.

6. The method of claim 5 wherein uniform quantities of cooled particulate wax are volumetrically measured into a die cavity, and cakes substantially free of internal stresses and of substantially uniform weight are produced therefrom by compression.

7. The method of manufacturing wax particles suitable for producing solid wax masses which are uniform in size and substantially free from internal stresses which method comprises cooling a thin layer of molten parafiin wax of about 122 F. to 124 F. melting point to a temperature in the range of about 82 F. to 94 F. to form a continuous flexible film of wax in a plastic state, cutting said film from both sides before it is cooled to a brittle state into particles of uniform size of approximately .01 to .04 inch thickness and cooling the cut particles to prevent their adherence to each other so that the cooled particles have a uniform bulk ratio below about 3.5, the bulk ratio being the ratio of a volume of unpressed wax particles to the volume of a solid wax obtainable therefrom.

8. The method of claim 7 which includes the further steps of placing a predetermined volume of said cooled particles into a die, pressing said particles to effect at least partial fusion thereof, and maintaining a film of liquid wax on the surface of the wax mass to avoid sticking of the wax to die surfaces.

9. Apparatus for processing a material which passes through a plastic state while being transformed from liquid to solid, which apparatus comprises, in combination, means for producing a continuous moving film of said material in the pliable plastic state, means for producing particles of substantially uniform size by cutting the moving film from opposite sides thereof while said film is in the plastic state, means for guiding said plastic film to said means for producing particles of substantially uniform size from said means for producing said plastic film and means for introducing cooled air into contact with the cut material to prevent adherence between particles and to provide a free-flowing mass of particulate material.

10. The apparatus of claim 9 which includes means for die compressing volumetrically measured quantities of the particles of substantially uniform size to solid objects having substantially uniform weight and substantial freedom from internal stress.

11. Apparatus for processing paraffin wax which comprises a tank of molten wax, a rotatable drum cooler mounted above said tank having a segment of its periphery immersed in said Wax whereby upon rotation of the drum a film of wax adheres to said periphery and is cooled to yield a continuous moving film of wax in the pliable, non-brittle plastic state, a scraper blade in contact with said drum to remove said continuous pliable film, means for comminuting said moving film while in the pliable, non-brittle plastic state to particles having a bulk ratio not greater than about 4 and of substantially uniform size by cutting said moving film from opposite sides thereof, means for guiding said film to said comminuting means, an enclosure extending downward from the discharge side of said comminuting means and means for introducing cooled air into said enclosure for cooling the cut wax as it is discharged from said comminuting means.

12. The apparatus of claim 11 which includes a means for die compressing volumetrically measured quantities of the wax particles into cakes of substantially uniform weight and substantial freedom from internal stress.

13. Apparatus for converting molten wax into substantially uniform wax particles suitable for producing solid wax masses substantially free from internal stresses and having a bulk ratio less than about 4 which apparatus comprises in combination means for transforming said molten Wax into a moving pliable plastic film, means for cutting said moving film from opposite sides thereof while said film is in the pliable plastic state, to produce uniformly particulate solids and means for introducing cooled air into contact with the cut wax in order to prevent adherence between particles and provide a free flowing mass of particulate wax.

14. The apparatus of claim 13 which includes a means for die compressing volumetrically measured quantities of the cut wax into cakes of substantially uniform weight and substantial freedom from internal stress.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,178,386 Edwards Apr. 4, 1916 1,525,590 Perrault Feb. 10, 1925 2,245,640 Beattle June 17, 1941 2,335,515 Jehle Nov. 30, 1943 2,360,275 Rau Oct. 10, 1944 2,461,089 Smidth Feb. 8, 1949 2,499,359 Cox Mar. 7, 1950 2,516,295 Borton July 25, 1950

Claims

5. THE METHOD OF CONVERTING MOLTEN WAX INTO SUBSTANTIALLY UNIFORM WAX PARTICLES SUITABLE FOR PRODUCING SOLID WAX MASSES SUBSTANTIALLY FREE FROM INTERNAL STRESSES AND HAVING A BULK RATIO NOT GREATER THAN ABOUT 4 WHICH METHOD COMPRISES PASSING THE PERIPHERY OF A COOLED DRUM THROUGH A TANK OF MOLTEN WAX TO PRODUCE A CONTINUOUS NON-BRITTLE PLASTIC FILM OF WAX THEREON HAVING A THICKNESS NO GREATER THAN ABOUT .04", REMOVING SAID NON-BRITTLE