US2692118A

US2692118A - Method and apparatus for controlling the temperature of rolls

Info

Publication number: US2692118A
Application number: US78378A
Authority: US
Inventors: Holloway James Phillip
Original assignee: Armstrong Cork Co
Current assignee: Armstrong World Industries Inc
Priority date: 1949-02-25
Filing date: 1949-02-25
Publication date: 1954-10-19
Anticipated expiration: 1971-10-19

Description

Oct. 19, 1954 J. P. HOLLOWAY 2,592,113

METHOD AND APPARATUS FOR CONTROLLING THE TEMPERATURE OF ROLLS Filed Feb. 25,1949

JA ES'PHILLIP HOLLOWAY 2s 27 4 Patented Oct. 19, 1954 METHOD AND APPARATUS FOR CONTROL- LING THE TEMPERATURE OF ROLLS James Phillip Holloway, Manheim Township,

Lancaster County, Pa., assignor to Cork Company, Lancaster, Pa., a

of Pennsylvania Armstrong corporation Application February 25, 1949, Serial No. 78,378

6 Claims.

The present invention is directed to a method and apparatus for controlling the temperature of rolls and more particularly to the method and apparatus for controlling the temperature of a calender roll. The invention finds particular usefulness in the asphalt tile field where proper temperature control at the working surface of the calendering rolls used in sheet formation is desirable in order to produce a high quality sheet.

In the manufacture of asphalt tile, it is common practice to first mill the composition upon milling rolls and deliver the milled mass in sheet form to a two-roll calender Where the sheet is reduced in thickness and a desired surface finish is effected by the calendering operation. Generally the sheet as delivered to the calender from the milling rolls is at an elevated temperature; and, in order to obtain the desired surface finish and prevent excessive adherence of the mass to the rolls, the rolls are internally cooled. Brine is frequently used as the coolant and may be at a temperature of 20 F., for example. The face roll is generally maintained at a higher temperature than the back roll (about 20 to 30 F. higher) and temperature control on this roll is more necessary than on the back roll.

It has been found in the manufacture of asphalt -tile that the temperature at the working surface of the rolls may be controlled effectively by the circulation of brine within the roll body, except for areas adjacent the roll necks where heat transfer is more rapid than at the center of the working surface of the roll. The mix which is fed to the calender in heated condition tends to heat up the working surface to a higher degree throughout the major portion of the area of the working surface in contact with the sheet than in the narrow bands beyond the edges of the sheet Where heat is not supplied by the sheet during formation. As a consequence, such edges of the working surface are relatively colder than the central portion, and the finished product is deleteriously affected by such temperature differential because too much heat is extracted from the sheet adjacent its longitudinal edges.

It "is an object of this invention to provide a method and apparatus which will make it possible to extract heat from a roll by internal cooling and apply heat to the edges of the roll adjacent the roll necks to compensate for differences in temperatures existing there, avoiding the creation of zones at the working surface Where a temperature differential exists and affects proper product formation.

Another object of the invention is to provide a system for controlling the temperature of an internally cooled roll by the application of heat to the roll in a selected area or areas of the working surface Where excessive heat extraction may be encountered.

In order that the invention may be better understood, I shall describe the same in conjunction with the attached drawing in which:

Figure 1 is a diagrammatic view in elevation showing an embodiment of the apparatus of the present invention which will be useful in the practice of the method of the invention;

Figure 2 is a sectional view taken on the line II-II of Figure 1; and

Figure 3 is an enlarged sectional view of one of the heating shoes taken on the line III-III of Figure 1.

In Figure 1 there is shown a two-roll calender which includes a conventional calender framework 2, a top or face roll 3, and a bottom or back roll 3. Both of the rolls may be internally cooled, although only one has been shown as provided with a cooling system in the embodiment chosen for illustration. The internal cooling may be effected by means of a fluid coolant such as brine led into the interior chamber 5 of the roll 3 through an inlet 6 and discharged through an outlet 7. This will be effective for extracting heat from the working surface 8 of the roll 3. In Figure 1 a sheet 9 is shown in section between the rolls 3 and 4. Illustratively this may be a sheet of asphalt tile composition delivered from milling rolls at a temperature in the order of 180 to 250 F., for example. The sheet may be about /2 inch thick, about 42 inches wide, and of indefinite length. The rolls 3 and t may be set to produce a finished sheet f inch thick. In operating upon a sheet at such temperature under these conditions and injecting brine into the cavity 5 at a temperature of 20 F., the temperature at the working surface 3 of the roll 3 may be in the neighborhood of to F. throughout the major portion of the surface 6 which is in contact with the sheet 9. There will be a gradual decrease in the temperature from the roll necks l0 and H to points 12 and E3 which are disposed inwardly from the edge of the sheet 9, because heat is conducted rapidly away from the sheet in such zones. Consequently, these areas of the formed sheet are improperly finished and may have cold checks and other defects on the face. In marble type of patterns, the graining will be different in these cold areas than in the remaining portion of the sheet where proper heat extraction has been effected, but not excessive extraction. The width of the zones where too great an amount of heat is extracted will vary depending upon operating temperatures and other conditions.

According to the present invention there is mounted on the machine frame 2 for engagement with a portion of the periphery of the roll 3 heating shoes Ill and i5, one being disposed on each of the edges of the roll 3 adjacent the roll necks l and II. One of the shoes, is shown in some detail in Figures 2 and 3. It includes a bearing bronze shoe l6 which has a surface ll of arouate formation adapted to lie in close engagement with the working surface 8 of the roll 3 as shown in Figures 1 and 2. The shoe [6 is preferably cast and is cored out to provide a chamber 18 which preferably receives a heating coil l9 which is positioned closely adjacent the lower surface of the casting IE and is filled with lead 20 to a level about parallel with the upper surface of the coil l9. Insulation material 2| is disposed above the coil and the lead matrix and serves to prevent the loss of heat to the atmosphere, conserving it for application to the surface portion ll of the shoe. A cover plate 22 closes the chamber H3 in the shoe.

A mounting bracket 23 is provided for securing the shoe member to the frame 2 or the machine for free pivotal movement and for a limited movement transversely of the pivot so as to permit the shoe to ride in full contact with the working surface 5 of the calender roll. The bracket 23 is provided with a stud 2A which includes a pivot 25. The shoe is has a bifurcated extension 28 which is provided with a slotted opening 27 adapted to receive the pivot 25.

Jam nuts

28 and 29 are provided for positioning the shoe i6 on the bracket while permitting free movement of the shoe about the pivot and also laterally with respect thereto in the slotted opening 2?. Cap screws Si] and 31 fasten the bracket 23 to the frame 2.

The width of the shoes will vary depending upon the heating requirements, in order to compensate for losses adjacent the roll necks. In the embodiment illustrated, the shoes are about 4 inches wide and extend over about 120 of the circumference of the roll as indicated in Figure 2. Steam at a temperature of about 300 F. has been found effective for raising the temperature in the areas in contact with the shoes to a degree where a substantially uniform product is obtained, eliminating the cold cracks and the other defects resulting from improper temperature control. The steam temperature or quantity supplied to the coil 59 through inlets 32 and discharged through exhaust 33 will depend upon the sheet temperature, coolant temperature, ambient atmospheric temperature, and other variable factors.

While it is preferred to use a steam heating system as shown, the shoes may be heated with gas flames, for example, and equivalent results secured. It will be observed that the shoes are disposed on the upper portion of the rolls where they will not come into contact with material being calendered, and they are effective for heating the outer surface of the roll immediately prior to contact of the material to b calendered with the roll. The heating is effected continuously as the calender rotates; and, since the surface of the roll is in contact with the material for a relatively short period of time, as the material passes through the nip between the rolls, it is not necessary to heat the roll to any substantial depth,

While the invention has been described in connection with the manuacture of asphalt tile, it is not limited thereto, for there are many instances in other arts where similar problems of temperature control present themselves, and the device and method of the present invention will offer a solution to many of those problems.

While I have illustrated and described a preferred embodiment of the invention, it will be understood that the same is not limited thereto but may be otherwise embodied and practiced within the scope of the following claims.

I claim:

1. In an apparatus for controlling the temperature at the substantially cylindrical working surface between the necks of a roll, th combination of means for injecting coolant into the interior of the roll throughout substantially the entire area of the roll interior which is opposite to the working surface of the roll to extract heat from the working surface and means for supplyin heat directly to the peripheral end portions of the outer cylindrical working surface adjacent to the roll necks to compensate for heat losses from the working surface to the necks.

2. In an apparatus for controlling the temperature at the substantially cylindrical working surface between the necks of a roll, th combination of means for injecting coolant into the interior of the roll throughout substantially the entire area of the roll interior which is opposite to the working surface of the roll to extract heat from the working surface and means for supplying heat directly to the peripheral end portions of the outer cylindrical working surface adjacent to the roll necks to compensate for heat losses from the working surface to the necks comprising metal shoes engageabiewith the outer cylindrical working surface adjacent the roll necks, and means for heating the shoes.

3. In a calender including a pair of calender rolls mounted in a frame for rotation, an apparatus for controlling the temperature at the outer cylindrical working surface of at least one of the calender rolls comprising means for injecting coolant into the interior of the roll throughout substantially the entire area of said roll interior which is opposite to the working surface of said roll to extract heat from said working surface and means for supplying heat directly to the peripherai end portions of the outer cylindrical working surface adjacent to the roll necks to compensate for heat losses from said working surface to said necks, said last named means comprising a heating shoe having a surface for engagement with a substantial portion of the outer cylindrical working surface of the roll at a pcripheral end portion thereof adjacent One neck of the roll, a mounting bracket affixed to the calender frame, a pivot affixed to th mounting bracket, attaching means on the shoe having an elongated opening for the reception of said pivot, said shoe being movable with respect to said pivot in a motion of rotation and in a motion of translation, whereby said shoe is free to pivot and move transversely with respect to said pivot to bring said shoe into engagement with the arcuate surface of the calender roll, and means for heating the shoe.

4. In a method of controlling the temperature at the outer cylindrical working surface of a cooled calender roll against which a heated sheet of plastic material is pressed in calendering, the temperature of the cooled working surface of said roll being substantially lower than the temperature of said sheet, the steps comprising internally cooling said roll to extract heat from said working surface of said roll which engages said sheet, the temperature of which is higher than that of said working surface, to thereby obtain a substantially uniform temperature in the area of the roll which engages said sheet, except adjacent to the longitudinal edges of said sheet where heat is conducted away from said sheet at a more rapid rate than at the other portions thereof, and applying heat to the peripheral end portions of the outer cylindrical workin surface of said roll in advance of contact of said working surface with said heated sheet of plasitc material to increase the temperature of the cooled Working surface in said peripheral end portions to compensate for such more rapid rate of heat conduction from said sheet adjacent to its longitudinal edges.

5. In a method of controlling the temperature at the outer cylindrical working surface of a cooled calender roll against which a heated sheet of plastic material is pressed in calendering, the temperature of the cooled working surface of the roll being substantially lower than the temperature of said sheet, the steps comprising circulating a coolant interiorly of said roll to reduce the temperature at said working surface of said roll to a degree substantially below the temperature of said heated sheet of plastic material to be calendered and applying heat to the peripheral end portions of the outer cylindrical working surface of said roll to compensate for a more rapid rate of heat conduction from said sheet to said r011 adjacent to the longitudinal edges of said sheet.

6. In a method of controlling the temperature at the outer cylindrical working surface of a cooled calender roll against Which a heated sheet of plastic material is pressed in calendering, the temperature of the cooled working surface of the roll being substantially lower than the temperature of said sheet, the steps comprising interiorly cooling said roll to extract heat from said working surface of said roll which is to engage said sheet, bringing said heated sheet of plastic material into engagement with said working surface with said sheet at a temperature substantially above the temperature of said working surface, and directly applying heat to the peripheral end portions of said outer cylindrical working surface of said roll in an amount sufficient to bring said working surface in such areas to a degree substantially equivalent to the temperature of other portions of said working surface in direct contact with said sheet being operated upon.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,519,314 Koupal Dec. 16, 1924 1,638,626 Fox Aug. 9, 1927 1,699,902 McCrery Jan. 22, 1929 1,978,894 Clark Oct, 30, 1934 2,184,908 Chan Dec. 26, 1939 FOREIGN PATENTS Niunber Country Date 512,636 Germany Nov. 15, 1930