US3395636A - Construction of roll for machinery - Google Patents

Description

R. A. HESS Aug. 6, 1968 CONSTRUCTION OF ROLL FOR MACHINERY Filed April 27, 1966 FIG.I

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United States 3,395,636 CONSTRUCTION OF ROLL FOR MACHINERY Ralph A. Hess, Medfield, Mass., assignor to SW Industries, Inc., Newton, Mass., a corporation of Massachusetts Filed Apr. 27, 1966, Ser. No. 545,597 8 Claims. (Cl. 100-93) ABSTRACT OF THE DISCLOSURE The present invention relates to a novel roll construction of the type useful in a variety of machines, particularly paper making and processing machines, etc., and, more particularly, to a roll construction of the type having a metallic core, the extremities of which are journaled, and an elastomeric covering or veneer, the physical and chemical properties of which are particularly selected. The roll construction of the present invention is specifically adapted for use in a calendering process wherein it rotatably presses against a rotatably mounted heated drum. The covering, which is relatively hard and thin is intended to compact the surface of a paper or paperboard sheet that is advanced between the roll and the drum for the purpose of providing gloss. In this process, it is desired that the roll covering maintain its predetermined hardness throughout long periods of time at elevated temperatures.

The primary object of the present invention is to provide a novel roll construction comprising a metallic core and a coverin incorporating, in a synthetic elastomeric matrix, a network of dispersed carbon particles, which have been found to conduct, to the roll core as a heat sink, heat generated within the covering as the roll continuously deforms during rotation and heat transmitted to the covering from the drum or the like, toward which it is pressed. It has been found that a covering of the foregoing composition is capable of maintaining exceptionally constant hardness throughout a broad, high temperature range.

Other objects of the present invention will in part be obvious and will in part appear hereinafter.

For a fuller understanding of the nature and objects of the present invention, reference should be had to the following detailed disclosure, taken in connection with the accompanying drawing, wherein:

FIG. 1 is an exaggerated, cross-sectional view of a roll construction of the present invention;

FIG. 2 is an exaggerated cross-sectional View of a calendering station, for example, in a .paper making ma chine, embodying the present invention; and

FIG. 3 is a graph illustrating certain principles of the present invention.

Generally the roll construction embodying the present invention, as shown in FIG. 1, comprises as components: a cylindrical metallic core 10, preferably composed of cast iron, bronze or steel; and a tubular covering 12, preferably composed of an elastomeric external phase 14 and a carbon internal phase 16, in the form of a continuous network of minute particles which are sufficiently closely adjacent to provide a continuous path for the conduction of heat. In order to achieve such heat conductive characteristics, the carbon is present in an amount ranging from 20 to 80 parts based on 100 parts of elastomer and is in the form of particles generally ranging in mean diameter between and 40 millimicrons. Remaining comatent ponents of the covering include suitable plasticizers, antioxidants and ifillers. As suggested in FIG. 2, the roll structure of FIG. 1 is shown at 18 as the top roll of a calendering station having a heated drum 20. Typically, heated drum 20 is maintained at a temperature, e.g., 300 to 400 F., higher than the temperature of roll 18, which is grounded at alower temperature, e.g., 140 to 190 F. Roll 18 generally ranges from 14 to 30 inches in overall diameter and its covering generally ranges from A to 1 inch in thickness. The overall length of drum 20 is similar to that of roll 18 and its diameter generally ranges from 18 to 66 inches. Typically, the pressure between roll 18 and drum 20 ranges between 300 and 600 pounds per lineal inch. For best results, the hardness of covering 12 ranges from 3 to 20 P&] for a inch ball. (The use of the P&] hardness tester is described in ASTM D53149).

The process of producing covering 12 generally comprises the step of (a) mixing the elastomeric matrix, which is in partially polymerized form, and the carbon particles, and blending therewith a plasticizing agent, an antioxidant and a filler, (b) adding an accelerator in order to time the occurrence of vulcanization at some later specified time, (c) applying the blend to a metal core, and (d) heating from 5 to 35 hours at a temperature from 250 to 350 F., the time range of 19 to 21 hours and the temperature range of 260 to 270 F. being preferred. It is to be realized, of course, that cure is a function of both time and temperature and, therefore, that cure may be varied widely within the foregoing limits.

Generally, the formulations discussed below are based upon 100 parts elastomer, suitable elastomers being synthetic rubbers such as chloroprene, butadiene-styrene, butadiene-acrylonitrile, chlorosulfonated polyethylene, and ethylene-propylene terpolymer. Such synthetic elastomers, unlike natural elastomers, are not subject generally to chain scission at elevated temperatures. Generally, as indicated below, the carbon content, which ranges from 20 to by weight of elastomer, is in the form of par ticles having a mean diameter of from 10 to 40 millimicrons, being characterized by physical properties, by which network formation inherently occurs. Such a carbon is sold by Columbian Carbon Co. under the trade designation Conductex. This carbon network contributes its inherent heat conducting characteristics to the elastomeric matrix in which it is dispersed without appreciably affecting adversely the desirable characteristics of the elastomeric matrix. This network has the ability to withstand deformation of the elastomeric matrix without any break in its continuity during deformation of the roll during use.

Generally, all of the below-mentioned additives are specified in terms of parts by weight based on parts by weight of elastomer. A plasticizing agent is present in the quantity from 0 to 50 parts, suitable plasticizing agents being coumaron indene resins, low molecular weight hydrocarbons such as glycol, and esters such as dioctyl phthalate. Generally an antioxidant is present in the quantity from 0 to 5 parts, suitable antioxidents being phenyl alpha naphthalene, N-phenyl-betal-naphthalene, alkylated phenol, isopropyl laminodiphenyl and naphthalene. Generally a filler is present in the quantity from 0 to 700 parts, suitable fillers being an inorganic material such as calcium carbonate, silica, barium sulfate, hydrated aluminum silicate, magnesium silicate. Processed organic materials also may be used, including vulcanized vegetable oil chlorinated vegetable oil. Generally an accelerator is present in the quantity from .1 to 30 parts, suitaable accelerators, including inorganic accelerators, such as lime and lead oxide and organic accelerators, such as peroxide, mercapto-benzothiozole, benzothiazyl disulfide, tetramethyl thiuram monosulfide, zinc dibenzyl dithiocarbamate, Zinc dibutyl dithiocarbamate, butylaldehyde analine, diphenyl guanidine, diorthotoly guanidine.

3 Generally a vulcanizing agent is present, such as sulfur in the quantity of 0.1 to 45 parts or magnesium oxide in the quantity 1-20 parts.

The following nonlimiting examples further illustrate the processes and products of the present invention.

EXAMPLE I First the following covering materials were thoroughly blended by mixing for 75 minutes.

Parts by weight Elastomeric butadiene-styrene (70/30 weight The core which was composed of iron and. was 24 inches in diameter, was grit blasted and coated with a layer, 0.001 inch thick, of a cement incorporating neoprene in a ketonic solvent. Thereafter a cement having the following formulation was applied in a layer 0.001 inch thick: Parts by weight Neoprene 100.

Magnesia 4.

Phenyl alphanaphthalene 2.

Calcium silicate 10.

Zinc oxide 5.

Methyl ethyl ketone Sufficient quantity to disperse solids representing by total weight.

After drying the foregoing cement, the previously specified covering as was applied onto the core in a layer /2 inch thick. Then, the veneer was cured at 260 F. for 20 hours. Finally, the outer surface Was smoothly ground. It was found that the roll of the foreging composition had the curve of hardness vs. temperature shown at 22 in FIG. 3. The corresponding curve of the same composition without the conductive carbon network is shown at 24 in FIG. 3.

EXAMPLE II The process of Example I was repeated except that the parts per weight of sulfur was doubled. The resulting covering was harder than the covering of Example I but exhibited a substantially constant hardness vs. temperature curve analagous to that of curve 22 in FIG. 3.

The present invention thus provides a calender roll exhibiting unusually constant hardness throughout a very wide temperature range. Since certain changes may be made in the foregoing disclosure without departing from the scope of the invention disclosed herein, it is intended that all matter described in the foregoing description or shown in the accompanying drawings be interpreted in an illustrative and not in a limiting sense.

What is claimed is:

1. A calendering roll construction comprising a press roll and a heated roll, said press roll including cylindrical inner core and a tubular outer covering, said inner core being composed of metal and having means at its opposite extremities for mounting said roll construction for rotation, said tubular covering being composed of a synthetic elastomeric matrix and a dispersed network of heat conductive carbon particles therein, the concentration of said carbon particles ranging between 20* to based on elastomer of said matrix and said particles substantially ranging in size between 10 and 40 millirnicrons, said heated roll having a metallic surface.

2. The calendering roll construction of claim 1 wherein said heated roll is maintained at a temperature of 300 to 400 F.

3. The calendering roll construction of claim 1 wherein the pressure between said press roll and said heated roll is maintained at between 300 to 600 pounds per lineal inch.

4. The calendering roll construction of claim 1 wherein said press roll varies in temperature from 140 to 190 F.

5. The calendering roll construction of claim 1 wherein the hardness of said covering ranges from 3 to 20 P81] for a inch ball.

6. The calendering roll construction of claim 1 wherein said covering ranges from /4 to 1 inch in thickness.

7. A roll construction comprising a press roll and a heated roll, said press roll including cylindrical inner core and a tubular outer covering, said inner core being composed of metal and having means at its opposite extremities for mounting said roll construction for rotation, said tubular covering being composed of a synthetic rubber matrix and a dispersed network of heat conductive carbon particles therein, the concentration of said carbon particles ranging between 25 to based on elastomer of said matrix and said particles substantially ranging in size between 10 and 40 millirnicrons, said heated roll having a metallic surface, means for maintaining said heated roll at a temperature of 300 to 400 F., means for maintaining the pressure between said press roll and said heated roll at a pressure of 300 to 600 pounds per lineal inch, means for maintaining the temperature of said press roll from to F., the hardness of said covering ranging from 3 to 20 P&J. for inch ball, the cove-ring ranging from A to 1 inch in thickness.

8. A calendering roll construction comprising a press roll and a heated roll, said press roll including cylindrical inner core and a tubular outer covering, said inner core being composed of a heat conductor and having means at its opposite extremities for mounting said roll construction for rotation, said tubular covering being composed of a synthetic elastomeric matrix and a dispersed network of heat conductive carbon particles therein, the concentration of said carbon particles ranging bebetween 20 to 80% based on elastomer of said matrix and said particles substantially ranging in size between 10 and 40 millirnicrons, said heated roll having a heat conducting surface.

References Cited UNITED STATES PATENTS 2,373,876 4/1945 Cutler 29-132 3,081,206 3/1963 Remer 29-132 X 3,092,895 6/1963 Balkin et a1. 29-132 3,189,729 6/ 1965 Lusebrink.

LOUIS O. MAASSEL, Primary Examiner.

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