US2709278A - Method of moulding wax - Google Patents

Description

F. W. GREER METHOD OF MOULDING WAX 2 Sheets-Sheet 1 Filed Nov. 3, 1951 n m m m n w m n m m Nwm INVENTOR BY Z14 WMkEaJ A TOKNEV WWW May 31, 1955 F. w. GREER METHOD OF MOULDING WAX 2 Sheets-Sheet 2 Filed Nov. 3, 1951 INVENTOR. 4 9 m mm w 4 TTO WVEP' METHOD OF MOULDING WAX Fred W. Greer, Belmont, Mass., assignor to J. W. Greer Company, Cambridge, Mass., a corporation of Massachusetts Application November 3, 1951, Serial No. 254,739

6 Claims. (CI. 18-58) This invention relates to the processing for transportation of paratfin wax, microcrystalline wax, and other types, produced in the normal gasoline and oil refining processes in the petroleum industry.

Paraffin waxes, once produced in surplus, have found increasing use in industry in the treatment of paper for food and other packaging uses, for insulation purposes and in the textile, leather, cosmetic and lumber industries, etc. These waxes are most readily transported from the refining plants to industrial users in the form of slabs weighing in the neighborhood of to 12 pounds per slab.

In order to avoid breakage, the slabs are about 1%" thick and their other dimensions may be, for example, 12" x 19", the dimensions being dictated to some extent by the size which is convenient for the customers use.

The process herein described is designed to supplant two traditional methods which have long been used in the petroleum industries.

The simpler method of the two merely involves handpouring of the molten wax into individual trays which are left to cool. These trays have tapered sides so that the slabs can be hand-dumped after cooling.

The second method, which is in general use today, is better than the above as it produces slabs with square edges which can be stacked on edge. Also, production can be greater due to better control of cooling conditions. This method employs a moulding press made up of a long series of alternately arranged U-shaped moulding frames and cooling plates which are hung in vertical sideby-side relation between supporting side bars and rammed into juxtaposition by a hydraulic ram, with the open sides of the Us up.

The cooling plates are hollow to permit circulation of cooling water, each plate being connected with two flexible hoses, inlet and outlet, thus involving for a IZO-mould frame machine, 240 flexible hose connections.

The top edges of the frames and plates are shaped to form a gutter, so that molten wax can be poured over the top. Pouring of an excess of wax is necessary for the production of uniform slabs, as the wax undergoes considerable shrinkage in solidifying. The excess wax is scraped off after the wax begins to set and such excess wax commonly both adheres to the apparatus and falls to the floor, causing unsafe working conditions, as well as producing considerable unusable scrap. After complete setting by the circulation of cold water through the cooling plates, the ram is removed and each one of the 120 plates then has to be pried loose from the Wax, usually with crowbars, and the slabs are then loosened and hand lifted from the moulds. All this is a tedious, unsanitary (a serious drawback when the Wax is destined for the food industry) and expensive labor operation, but the industry has in general accepted it as preferable to the 2,709,278 Patented May 31, 1955 "ice ness onto a conveyor belt submerged in cold water. After cooling sutficiently, the ribbon is cut into the desired lengths and subjected to additional cooling.

While this is a continuous and comparatively simple method, it produces slabs. of very uneven shape which cause extreme difiiculty in packaging. Many slabs are so warped that they must be remelted and remoulded.

l t is an object of this invention to provide a process for moulding wax slabs having the desired rectilinear configuration for proper stacking, which are of substantially uniform weight, but wherein hand labor is dispensed with and the slabs are produced in a continuous and automatic, as distinguished from a batch hand operation.

To this end, my process involves flowing molten wax into a shallow open-topped rectilinear vessel at a temperature slightly above its melting point and immediately cooling the wax by passing the vessel through a crosscurrent of air at a temperature well below its melting point to shrink and harden the wax, expelling the hardened slab from the vessel as by inversion of the vessel and then reconditioning the vessel for refilling and repeating the cycle.

The process is adapted to be carried out by automatic machinery including a conveyor for carrying a series of such vessels, successively to a filling device which may be a measuring feed, such as a positive displacement wax depositor, a cooling tunnel through which the conveyor advances the loaded vessels, a vessel inverter, and a reconditioning traverse returning the vessels successively to the filling device.

Such an arrangement is shown diagrammatically in the accompanying drawings, wherein:

Fig. l is a sectional plan view of an apparatus useful in performing the process of this invention;

Fig. 2 is an enlarged sectional elevational view (broken away to indicate extent) of the apparatus shown in Fig. 1;

Fig. 3 is a cross-sectional view through the cooling tunnel of the apparatus, omitting certain parts for the purpose of clarity;

Fig. 4 is a detailed perspective view of one row of wax receiving vessels; and

Fig. 5 is a perspective view of one of the wax slabs produced by my process.

Referring to Fig. 2, the dot-and-dash arrowed line indicates the path of an endless conveyor for moving vessels 12 which, starting at the right-hand lower corner of the figures, passes through a filling station below a wax-depositor i5 and then through a slot 17 at the entrance end of an insulated cooling tunnel 20. The conveyor then passes in the cooling tunnel 29 through a series of stacked traverses passing about a series of 180 turns at each end of the tunnel until the conveyor passes out of the tunnel 20 through a slot 22 at the top of the apparatus, and then through a vessel inverter 24, after which the conveyor passes downwardly between radiant heating elements 26. In Fig. 2 is also indicated an intermittently operated cross-conveyor adapted to receive the dumped wax slabs from the vessel inverter 24 and remove them from the machine.

The cooling tunnel 20 is divided horizontally into upper and lower sections by a centrally extending bafile parti-- tion 40 and the tunnel is provided along its length with a series of difiusers, each of which has associated therewith a blower o1 blowers 5) driven by motors 49 which direct air in the manner shown in Fig. 3, through ducts 51, across the top of the cooling tunnel, around the opposite side of the central baffie 40, and back again to the blowers 5i). Refrigerating coils 52 are placed as sho wn in order to cool the air before it re-enters blowers 59.

As shown in Fig. 4, the conveyor may comprise a pair of parallel sprocket chains guided and driven by suit-- ably located sprockets. Suspended between the chains is a compartmented vessel 12, each compartment having the desired length and width dimensions, preferably with its sides at right angles to one another and to the bottom. The vessel support points are pivotal connections 64 so that the vessel will be maintained in horizontal position as the sprocket chains pass about the pulleys to reverse the direction of the vessels. Suitable pins 66 are provided on the trays which engage cooperating fixed guides for this purpose, such arrangements being well known in the conveyor industry.

Likewise, a suitable molten wax depositor of the positive displacement type, having a plurality of discharge nozzles, which will automatically fill a cross row of compartments in timed relation with its passage along the continuously operating conveyor path is well known, the important feature being that the depositor fills each compartment with substantially the same weight of molten wax, so that the completed slabs will be of substantially uniform weight. Usually in a vessel having compartments of 12" x 19" dimensions which can be about 2 /2 deep, each compartment is filled to something slightly over 1%" depth. It will be understood that the wax discharge is intermittent and occurs only when a vessel is in proper position to receive the discharging wax. There is thus no spill or waste.

1 have found that if the temperature of the air fed from the diffusers is kept between 15 and 45 F., preferably between and F., sulficient shrinkage of the slab takes place during the cooling of the slab to cause it to pull away from the sides of the vessels when they are made of metal, such as steel, and the loose hardened wax slabs are readily expelled from the vessels at the dumping station merely by inverting them with the inverting device 24. The device may comprise a traveling canvas belt which engages the end of the vessel 12, as it passes to the left in Fig. 2, and cooperates in turning it over, and then travels parallel with the vessel bottom'so that the slab is resting on the belt from which it is discharged into the intermittently moving cross belt 30, which is stationary during discharge and then operates during the time interval required to advance the succeeding vessel to discharging position. The completed slabs, as shown in Fig. 5, are of uniform rectilinear configuration.

It has been found necessary with some types of wax to pre-heat the walls of vessels 12 to above the temperature of the melting point of the wax before they are refilled, such heating being conveniently accomplished by passing vessels 12 through a heating zone between radiant heaters '26 immediately before they pass to the filling station, thus conditioning the vessels for a new cycle of operation.

It is desirable to maintain the molten wax at the time of its delivery to the vessels at a controlled uniform temperature, depending upon the melting point of the wax, in order to insure uniform slab weights and cooling. In the apparatus shown, the reference indicates a pre-cooling unit which is in effect a heat exchanger adapted to lower the temperature of the wax from its relatively high storage tank temperature to a temperature closer to its melting point. This pre-cooling unit consists of water-jacketed tubing through which the liquid wax, entering from a storage tank at'inlet 81, is pumped. The flow of water is preferably counterflow to the flow of wax and suitable means, such as internal scrapers, can be provided, if necessary, in the tubes to prevent the build-up of an insulating film on the internal surface of the tubes. The pre-cooled wax then passes through pipe 82 to the depositor 15. Similarly, the depositor 15 may be water-jacketedwith a temperature control system for maintaining a proper temperature of the water in the jackets.

While vibrating or tapping mechanism may be provided with the inverter 24, I have found such a tapping mechanism to be unnecessary, as with cooling air temper'atures as hereinbefore set forth, the hardened wax slabs are easily removed by gravity from the inverted vessels 12. Uniformity in size and quality of the slabs, as well as the discharge thereof, is aided by maintaining a uniform predetermined temperature in the various areas of cooling unit during the moulding of any particular kind of wax. However, due to the separate diffusers, the temperature may be controlled with flexibility in setting the apparatus for any particular wax, either with the same temperatures at each diffuser or with variations progressively along the cooling tunnel. Of course, the air temperature as the current re-enters the diffuser is considerably higher than the temperature at which it entered the cooling tunnel from the diffuser due to the pick-up of heat from the wax. Another control is provided by blower 50 which can vary the velocity of the cross-current air flow with respect to the rate of the conveyor travel, the one precaution being that the velocity of air flow should not be so great as to ripple the molten wax surface, thereby detracting from the regularity of shape of the slabs. Thus, for example, with a wax which is deposited at a temperature of F., the temperature of the air leaving the blower 50 may be about 20 F., with the air flowing past the deposited wax at the rate of about 1,000 feet per minute. With such an operation, the conveyor may operate at 6 to 7 feet per minute, with a traverse in the cooling tunnel of about two hours,

the tunnel being about 64 feet long to give a total travel be apparent to those skilled in the art that various modifications may be made within the spirit of my invention and the scope of the appended claims.

I claim:

1.,A method of molding wax free of surface defects comprising flowing a measured quantity of molten wax into an imperforate shallow vessel to form a horizontally disposed unit of molten wax having an exposed top surface of substantially greater length and width than the depth of the unit, and, while said unit remains horizon-,

tally disposed, directing a forced current of air at a temperature between 15 and 45 F. across said vessel and said top exposed surface, to slowly cool and shrink the wax away from adherence to all the surfaces of said vessel and set the wax, and then inverting the vessel to expel the shrunken hardened wax slab by gravity,-

bottom side up, in its solidified form, from the vessel. 2. A method of moulding wax as claimed in claim 1 wherein a chain of said vessels is conveyed continuously through a wax depositing station, thence through a cool-' ing chamber, and thence through a slab expelling station.

3. A method of molding wax free of surface defects comprising flowing a measured quantity of molten wax into an imperforate shallow vessel to form a horizontally disposed unit of molten wax having an exposed top surface o f substantially greater length and witdh than the depth of the unit, and while said unit remains horizontally disposed, directing a forced current of air at a temperature between 15 and 45 F. across said vessel and said top exposed surface, for a period of about two hours to slowly cool and shrink the wax away from adherence to all the surfaces of said vessel and set the wax, and then; inverting the vessel to expel the shrunken hardened Wax slab by gravity, bottom side up, in its solidified form, from the vessel.

4. A method of molding wax as claimed in claim 3 wherein the unit of molten wax is rectilinear in shape.

5. The method of converting wax into clean slabs sub-' into successive mold pans having wall temperatures above I the melting point of the wax being deposited, continuously successively moving the pans through a cooling chamber and cooling the wax in said chamber slowly to a temperature well below its melting point to harden the wax and thence successively moving the wax-containing pans to a dumping station and dumping the wax.

6. The method of converting molten wax into clean slabs substantially free from surface defects which comprises lowering the temperature of the molten wax from its storage temperature closer to but still above its melting point, atnd then depositing the wax at the lowered temperature into successive mold pans, continuously successively moving the pans through a cooling chamber and cooling the wax in said chamber slowly to a temperature well below its melting point to harden the wax and thence successively moving the wax-containing pans to a dumping station and dumping the wax.

References Cited in the file of this patent UNITED STATES PATENTS 1,558,284 Paley Oct. 20, 1925 1,658,062 Sprague Feb. 7, 1928 2,035,117 English Mar. 24, 1936 2,476,710 Eaton July 19, 1949 2,677,151 Jennings May 4, 1954 2,677,152 Terry May 4, 1954

Claims (1)

1. A METHOD OF MOLDING WAX FREE OF SURFACE DEFECTS COMPRISISNG FLOWING A MEASURED QUANTITY OF MOLTEN WAX INTO AN IMPERFORATE SHALLOW VESSEL TO FORM A HORIZONTALLY DISPOSED UNIT OF MOLTEN WAX HAVING AN EXPOSED TOP SURFACE OF SUBSTANTIALLY GREATER LENGTH AND WIDTH THAN THE DEPTH OF THE UNIT, AND, WHILE SAID UNIT REMAINS HORIZONTALLY DISPOSED, DIRECTING A FORCED CURRENT OF AIR AT A TEMPERATURE BETWEEN 15* AND 45* F. ACOSS SAID VESSEL AND SAID TOP EXPOSED SURFACE, TO SLOWLY COOL AND SHRINK THE WAX AWAY FROM ADHERENCE TO ALL THE SURFACES OF SAID VESSEL AND SET THE WAX, AND THEN INVERTING THE VESSEL TO EXPEL THE SHRUNKEN HARDENED WAX SLAB BY GRAVITY BOTTOM SIDE UP, IN ITS SOLIDIFIED FORM, FROM THE VESSEL.

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