US3087198A - Rollers for film quench bath - Google Patents

Description

April 30, 1963 H. L. sow/mos 3,087,198 ROLLERS FOR F Im vEucH'sAm Filed July .8. 1960 WATER SPRAY 5e HOLES INVENTOR. m sow/mos Harold 3,087,198 ROLLERS FOR FILM QUENCH BATH L. Edwards, Bartlesville, 01th., assignor to Phillips Petroleum Company, a corporation of Delaware Filed July 8, 1960, Ser. No. 41,668

6 Claims. (Cl. 1s--1s This invention relates to the production of thermoplastic film. In one aspect, it relates to apparatus for the production of thermoplastic film. In another aspect, it relates to apparatus for rapidly quenchinghot extruded thermoplastic film for high speed film production.

Some prior equipment is able to produce thermoplastic film at the rate of about 200 linear feet per minute. For economic reasons, it is alwaysadvantageous to increase production without proportional increase in capital investment or operating costs.

In thermoplastic film production apparatus wherein hollow rollers are employed for guiding the extruded film through a quench tank, it has been found that temperature of the coolant liquid is not uniform throughout the length of the hollow rollers. Such a condition easily contributes to production of a non-uniform product, and further, reduces the rate of film production. At locations within the roller near either end thereof, coolant temperatures are very nearly those of the main portion of the coolant bath. At points near the center of'the rolls, longitudinally, temperatures frequently are higher than in the body of the coolant bath. While in the present case, I will describe the coolant bath as being a water bath, it is realized that the coolant need not necessarily be water for the application of this invention. used and particularly whenever possible because of its low cost and ready availability. In film producing equipment in which the thermoplastic film is extruded at a temperature around 400 to,440 F., the extruded film is directed immediately into a water quench bath at a water temperature frequently maintained around 135 F. When producing such film at a linear rate of approximately 200 to 400 feet per minute, the temperature of the water at approximately the longitudinal middle of the roller varies from 5 to maintained in the main body of the coolant. Since the temperature at the axial center of the roller is higher than at the ends of the roller it is realized that a nonuniform product is produced. Furthermore, when the temperature throughout the entire quench tank, including the interior of the rolls, is more nearly uniform, film can be produced at increased rates. For successful high speed operation, adequate water circulation, coupled with uniformity in temperature throughout the entire bath, is an absolute necessity. For example, in a SO-gallon quench tank, water should be changed at least every 5 minutes. Thus, to change a SO-gallon tank of water every 5 minutes requires use of a pump with the effective delivery of not less than 10 gallons per minute. This water which is introduced into the tank should be distributed along one or two sparger pipes in such a manner as to produce as little turbulence as possible. Uniform temperature can obviously be obtained throughout the entire volume of the tank by injecting this recirculating water through the sparger pipes at a high velocity but such type of water injection is to be avoided because of the turbulence and uneven temperatures presented at difierent areas on the film being quenched. Furthermore, turbulence within the body of water in the tank causes surfaces ripples, and ripples and splashes can easily produce holes in the soft film prior to and during the time it is the tank. Also, ripples and splashes of water frequently contact metal portions of the film die head which are normally positioned at a location very close to the surface of F. above the temperature entering the water in the water and cool these portions of the die head with the result that imperfect extrusion of the film frequently results. 1 v

It is possible to-obtain uniform temperature throughout the entire quench tank by provision of power operated stirring apparatus. However, such equipment tends to cause turbulence withinthe body of water with the result that ripples and splashes areobtained with the abovcmentioned disadvantageous results.

An object of this invention is .to provide for the efficient and rapid production of thermoplastic film. Another object of this invention is to provide apparatus for producinggthermoplastic film at increased production I rates. Still another object of this invention is to provide apparatus suitable and particularly adapted for the production of thermoplastic film of uniform quality. Yet

another object of this invention is to provide apparatus which assists in maintenance of uniform temperature Water is commonly throughout the quench bath without tubulence in the water with its undesirable effects. Still another object of this invention is to provide apparatus for circulating the coolant, as water, through the roller tubes at rates more or less proportional. to the rate of production of the film. Still other objects and advantages of this invention will be realized upon reading the following description which taken with the attached drawing forms a part of this disclosure. i

In the drawing, FIGURE 1 illustrates, in diagrammatic form, one embodiment of quench tank including the rollers with coolant circulation equipment of this invention. FIGURE 2 is a sectional view taken on the line 2-4 of FIGURE 1. FIGURE 3 is a perspective view on an enlarged'scale of a roller with the impeller of this invention. FIGURE 4 is a partial view of an alternate embodiment of roller of this invention.

Referring to the. drawing, reference numeral 11 identifies the quench tank in which the rollers of this invention are disposed. An overfiow launder 13 is provided around the tank in under to receive the overflow water. Connected with the bottom of launder 13 is a ripe 27 for passage of water from the launder to a cooling apparatus, not shown, prior to recirculation to the tank through one or more sparger tubes 21 and 23. Hollow rollers 15, 17 and 19 are positioned in the tank as illustrated. The particular positioning of these three rollers can well be seen in FIGURE 2. The hot thermoplastic material flows through extruder 41 and thence through the film die head 39 and therefrom it passes downward as a film 43 into the quench tank. So as not to distort the shape of the extruded film, the film passes directly downward from the die head into the water in the tank. Very shortly after becoming immersed in the water in the tank, the film direction is changed by the first hollow roller 15 and it rected to follow a vertical path by the third roller 19. By the time the film leaves roller 19 and the water in this end of the tank, the film has a temperature of ap proximately F., the temperature of the quench water in the tank. By introduction of the recirculated and cooled water into this tank through sparger tubes 21 and 23, the main body of water is maintained at a relatively uniform temperature-without appreciable undesired turbulence.

However, with this degree of uniformity of temperature throughout the main portion of the quench bath, the temperature ofthe water within the rolls without the impellers is markedly higher than the temperature in 31. The impellers are provided with blades 33 positioned within the end of the tubes or rollers 15, 17 and 19. With the direction of rotation of the roller as indicated by the attached arrow, water enters the indicated end of the roller. On passage througlrthe rollers, the velocity of the water is increased by the presence of a second impeller at the discharge end thereof. This im-v peller is provided with blades 33 disposed or positioned in such a manner as to assist flow of water through the rollers. These impellers are rigidly fixed to the inner surfaces of the walls of the hollow rollers as by welding or other means of attachment. In this manner, it will be realized that the rate of flow of water through the hollow tubes is more'or less proportional to the rotational speed of the tubes. Thus, when a tube rotates at a speed of about 100 revolutions per minute, the water flows through the tube at a lesser rate than when the roller speed is 200 r.p.m. In any event, irrespective of the speed of these rollers, that is, when the speed is maintained within reasonable operational speed for quenching the extruded film, the water is passed through these rollers at such a velocity that upon discharge therefrom turbulence and rippling or splashing are notproduced. At each hub of the impeller is provided a journal 35 which is enclosed within a bearing and the roller is rotated merely by the traveling film of extruded plastic.

In the ends of the tank 11 are provided bathe plates 25 which support bearings, not shown, for accommodation of the journals 35. While any suitable type of bearing can be employed, it is preferred that the bearings be of the ball or roller type. A support 11a elevates tank 11 to a predetermined height.

To assist further in prevention of rippling of the surface of the cooling water, a baffle plate 47 is positioned as illustrated throughout the length of the tank 11.

The water in the tank is identified by reference numeral 29 while the cooled thermoplastic film is identified by reference numeral 45. i

If desired, the several hollow rollers can be power driven in place of being free for rotation by the passage of the film only. In the case of power driven rollers, a sprocket wheel 63 is provided on hub 65 as illustrated in FIGURE 4. Reference numeral 61 identifies the chain for rotating this type of hollow roller.

In one instance, the rollers of this invention were constructed of two inch diameter aluminum pipe with the surfaces of the impeller blades being positioned at a 30 degree angle with respect to the axis of the hollow roller. In each of the rollers, the impellers were four bladed impellers. Thermoplastic film, such as a polyethylene film, was extruded at the rate of 300 feet per minute. With rollers of two inch outside diameter and the film being extruded at the above-mentioned rate, the rollers rotated at a speed of 573 r.p.m. This rate of speed caused relatively rapid flow of water through the inside of the tubes and to such extent that the temperature of the water in all portions of the rollers was the same as that in the main body of the quench tank. Thus, in this case, the temperature of the water in the water bath was maintained at 135 degrees and that temperature was the temperature maintained throughout the entire length of the rollers.

While the above-mentioned rollers were described as being constructed of two inch outside diameter aluminum tubing or pipe, it is realized that other materials of construction can be employed. Other metals which are non-corrosive obviously can be used. However, it is preferable in some instances to use, for example, polyethylene tubing as the main body of the roller. Also, the impeller can be made of polyethylene.

One advantage of the use of light weight aluminum is that it is a good conductor of heat. An advantage in the use of a polyethylene tubing is that the entire hollow roller is relatively light. Rollers of these materials do not sag when suspended only at their ends. It is obvious 4 that when producing film or sheets of substantial width, it is not permissible for these rollers to sag at their centers in any manner whatever.

While it is disclosed and described herein that the water in the quench bath was maintained at a temperature of 135 F., it is realized that other suitable temperatures depending upon the particular conditions of operation desired and the products to be produced, can be used. It is further realized that when producing very wide film, for example or 12 feet, that the roller tubeshould be larger indiameter than the above-mentioned 2 inches. For example, when producing a film 10 or 12 feet in width, it is preferable to use aluminum or polyethylene tubing approximately 6 inches, or larger, in diameter so that the tubing will not sag in any manner whatever.

While certain embodiments of the invention have been described for illustrative purposes, the invention obviously is not limited thereto.

I claim:

1. In a film quench bath the improvement comprising an imperforate tubular roller having a smooth exterior surface from end to end and with both ends open, said roller being horizontally positioned toreceive and to guide extruded film passing through the quench bath, said roller having at least one impeller, said at least one im peller being positioned only at an end of and within said tubular roller, said at least one impeller being fixed to the inner surface of the tubular roller and being rotatable therewith, the axis of said at least one impeller coinciding with the axis of said roller, and said at least one impeller being adapted upon rotation of said roller to propel quench liquid into one end of said roller and out from the other end.

2. In a film quench bath the improvement comprising an imperforate tubular roller having a smooth exterior surface from end to end and with both ends open, said roller being horizontally positioned to receive and to guide extruded film passing through the quench bath, said roller having an impeller positioned only at an end of and within said tubular roller, said impeller being fixed to the inner surface of the tubular roller and being rotatable therewith, the axis of said impeller coinciding with the axis of said roller, and said impeller being adapted upon rotation of said roller to propel quench liquid into one end of said roller and out from the other end.

3. In a film quench the improvement comprising a nonperforate tubular roller having a smooth exterior surface from end to end and with both ends open, said roller being horizontally positioned to'receive and to guide extruded film passing through said quench bath, said roller having a separate impeller disposed only at each end of and within said roller, the axis of each impeller being disposed along the axis of said roller and each impeller having blades the outer ends of which are rigidly fixed to the inner surface of the tubular roller and so positioned as to propel quench liquid into said roller from one end, through said roller, and out from said roller at the other end.

4. An apparatus comprising, in operable combination, a thermoplastic material extruder, a film diehead, a film quench bath, said diehead being positioned to receive extruded thermoplastic material from said extruder and to extrude film of said material in a downward direction into said quench bath, said quench bath having an imperforate tubular roller with a smooth exterior surface from end to end and having both ends open, said roller being horizontally positioned to receive and to guide extruded film passing through the quench bath, said roller having at least one impeller, said at least one impeller being positioned within said tubular roller, said at least one impeller being fixed to the inner surface of the tubular roller and being rotatable therewith, the axis of said at least one impeller coinciding with the axis of said roller, and said at least one impeller being adapted upon rotation of said roller to propcl quench liquid into one end of said roller the other end.

5. An apparatus comprising, in operable combination. a thermoplastic material extruder, a film diehcad, a film quench bath, said diehead being positioned to receive extruded thermoplastic material from said extruder and to cxtrude film of said material in a downward direction into said quench bath, said quench bath having an imperforate tubular roller with a smooth exterior surface from end to end and having both ends open, said roller being horizontally positioned to receive and to guide extruded film passing through the quench bath, said roller having an impeller positioned within said tubular roller, said impeller being fixed to the inner surface of the tubular roller and being rotatable therewith, the axis of said impeller coinciding with the axis of said roller, and said impeller being adapted upon rotation of said roller to propel quench liquid into one end of said roller and out of the other end.

6. An apparatus comprising, in operable combination, a thermoplastic material extruder, a film diehead, a film quench bath, said diehead being positioned to receive ex truded thermoplastic material from said extruder and to extrude'film of said material in a downward direction into said quench bath, said quench bath having an imperforate tubular roller with a smoothexterior surface from end to and out of and and having both ends open, said roller being horizontally positioned to receive and to guide extruded film passing through the quench bath, sziitl roller having a scpu rate impeller diaposcd at least near each end and within said roller, the axis of each impeller being exposed along the axis of said roller and each impeller having blades the outer ends of which are rigidly fixed to the inner surface of the tubular roller and so positioned as to propel quenched liquid into said roller from one end, through said roller, and out from said roller at the other end.

References Cited in the file of this patent UNITED STATES PATENTS 352,394 Campbell Nov. 9, 1886 574,282 Sebastian Dec. 29, 1896 635,504 Nowuexi Oct. 24, 1899 797,171 Cerruti Aug. 15, 1.905

897,!33 Palmer Aug. 25, 1908 l,831,091 Bowers Nov. 10, 1931 2,179,035 Ferry Nov. 7, 1939 2,307,694 Malkc Jan. 5, 1943 2,444,000 Younger June 22, 1948 3,024,493

Kompass Mar. 13, 1962

Claims (1)

1. IN A FILM QUENCH BATH THE IMPROVEMENT COMPRISING AN IMPERFORATE TUBULAR ROLLER HAVING A SMOOTH EXTERIOR SURFACE FROM END TO END AND WITH BOTH ENDS OPEN, SAID ROLLER BEING HORIZONTALLY POSITIONED TO RECEIVE AND TO GUIDE EXTRUDED FILM PASSING THROUGH THE QUENCH BATH, SAID ROLLER HAVING AT LEAST ONE IMPELLER, SAID AT LEAST ONE IMPELLER BEING POSITIONED ONLY AT AN END OF AND WITHIN SAID TUBULAR ROLLER, SAID AT LEAST ONE IMPELLER BEING FIXED TO THE INNER SURFACE OF THE TUBULAR ROLLER AND BEING ROTATABLE THEREWITH, THE AXIS OF SAID AT LEAST ONE IMPELLER COINCIDING WITH THE AXIS OF SAID ROLLER, AND SAID AT LEAST ONE IMPELLER BEING ADAPTED UPON ROTATION OF SAID ROLLER TO PROPEL QUENCH LIQUID INTO ONE END OF SAID ROLLER AND OUT FROM THE OTHER END.

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