US 3838734 A
A temperature controlled roll mechanism such as in a supercalender for a paper machine with a first roll having an outer covering of composition having an upper temperature limit and a second opposed heated roll, and the first roll being maintained within its permissible temperature range by having an inner shell coaxially within an outer shell defining a thin annular coolant chamber with passages through the shell and coolant supplied from the space within the inner shell and coolant exhausted through a passage connected only at one end of the annular chamber.
Claims available in
Description (OCR text may contain errors)
United States Patent [191 Kilmartin Oct. 1, 1974 HEAT TRANSFER ROLL BODY Primary Examiner-Charles J. Myhre Assistant Examiner-Theo hil W. Streule Jr. 1 h P r  i Jo n A Kllmamn Portage Mmh Attorney, Agent, or FirmHill, Gross, Simpson, Van  Asslgnee: Beloit Corporation, Beloit, Wis. Sam n, Steadma Chiara & Simpson  Filed: Jan. 22, 1973 21 Appl. No.: 325,522 7] ABSTRACT A temperature controlled roll mechanism such as in a supercalender for a a er machine with a first roll  US. Cl. 165/90 34/124 p p  Int Cl Fzsd' 11/02 F28b 5/02 having an outer covering of composition having an  i /1 19 upper temperature limit and a second opposed heated roll, and the first roll being maintained within its permissible temperature range by having an inner shell lly within an outer shell defining a thin annular  References Cited coaxla coolant chamber with passages through the shell and UNITED STATES PATENTS coolant suppliedfrom the space within the inner shell 2,435,959 2/1948 Eaby l65/89 nd oolant exhausted through a passage connected g z only at one end of the annular chamber. I'll e 10 Claims, 3 Drawing Figures is l HEAT TRANSFER ROLL BODY BACKGROUND OF THE INVENTION The present invention relates to improvements in rolls for paper making machines and the like, and more particularly to an improved arrangement for maintaining the temperature of a roll within a permissible limit. As an example, such a roll is one covered with a composition material wherein the composition becomes hot with use, and unless cooled, will deteriorate or become too soft for continued use.
In a super-calender of a paper making machine, for example, one of the rolls in a roll couple is frequently covered with a composition material such as material known to the trade as Beltex. The opposing roll will be a polished metal roll which will be heated to a maximum temperature of 250F. Relatively high nip pressures are employed in these arrangements on the order of a maximum of I700 pli, and it is essential that the composition cover of the one roll not be permitted to reach 250, or it will soften and deteriorate. It is also essential that when the covered roll is cooled, that the cooling be uniform so that the temperature differential along the length of the roll does not exceed to Different arrangements have been employed to attempt to cool the covered roll, such as directing a flow of air through air nozzles at the. covered roll, but these arrangements have not been wholly satisfactory and have been incapable of removing sufficient heat at high op erating speeds.
Another problem which has been faced is with the use of a crowned roll which creates a nonuniform temperature in the covered roll, generating a higher temperature in the middle and at the ends. This is not as serious as in the case of a cotton filled roll. but in certain covered rolls, the increased temperature in the center will exceed the permissible operating level and will change the physical hardness of the roll so that it is nonuniform throughout its length.
Other efforts to cool such rolls have included inducing a flow of coolant into the interior of the filled roll. One difficulty inherent with such an arrangement is that there has been no way to obtain uniform circulation of the coolant which tends to build up a layer of noncirculating fluid against the inner surface of the roll shell. This noncirculating fluid reaches a higher temperature than the fluid layer adjacent to it and any inequality in circulation will result in an inequality in heat removal, and thus nonuniform temperature of the roll cover. Such nonuniform roll cover temperature can cause the roll cover to reach deterioration temperatures or reach a condition of excessive softness, or cause a condition of nonuniform resiliency or softness along the length of the roll, thus in turn resulting in nonuniform calendering of the web passing through the mp.
It is accordingly an object of the present invention to provide an improved cooling or heat transfer mechanism which is simple and reliable in construction and effectively cools a roll to obtain a uniform temperature along its length.
A further object of the invention is to provide an improved roll structure which is cooled by a circulating coolant wherein the quantity of coolant circulated is substantially reduced while still obtaining effective cooling.
A further object of the invention is to provide an improved cooled roll structure utilizing a liquid coolant which does not drain to become overheated when it is stopped and wherein the coolant circulating construction is improvedover structures heretofore available.
Other objects, advantages and features will become more apparent, as will equivalent structures which are intended to be covered herein, with the teaching of the principles of invention in the disclosure of the preferred embodiment thereof in the specification, claims and drawings, in which:
DESCRIPTION OF THE DRAWINGS FIG. I is a somewhat schematic vertical sectional view taken through a roll assembly constructed in accordance with the principles of the present invention;
FIG. 2 is a fragmentary enlarged view showing details of the roll construction; and
FIG. 3 is a sectional view taken substantially along line IIIIII of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS As illustrated in FIGS. 1 and 2, a roll mechanism is shown including a first roll 10, forming a pressure nip with a second roll 11. The construction provides a super-calender wherein a paper web is passed through the nip to be calendered. While advantages are obtained in this particular environment of the invention, it will be understood that certain features of the invention may be utilized in other arrangements, but for this description, the structure will be described as used in a paper machine.
The roll 1 l is heated to a temperature of on the order of 250F. This temperature is too hot for the resilient composition covering 13 of the roll 10. The roll 10 has a roll shell 12 of metal which provides a rigid base on which the covering material 13 is supported. For cooling the covering material 13, heat is transmitted through the metal base 12 to be removed by a coolant in a manner which will be described.
For supporting the roll 10 in rotation, disks l4 and 15 are pressed into the ends of the roll shell, and these disks carry journals l6 and 17 to be supported in bearings for rotatably carrying the roll 10.
Coaxially mounted within the outer shell 12 is an inner shell 18. This inner shell defines a thin annular chamber 20 between its outer surface and the inner surface of the outer shell 12. Coolant is delivered and maintained in an axial flow through the thin annular chamber 20 by being admitted through a pluralityof openings 19 through the inner shell. These openings 19 are constructed so that a greater flow is received into the end 200 of the annular chamber than the end 20b. The end 20b is adjacent coolant exhaust passages 23 through which the coolant is removed from the chamber 20. In other words, a greater amount of coolant is admitted to the annular chamber 20 at the end 20a which is remote from the coolant exhaust passages 23 than in the end 20b which is adjacent the coolant ex haust passages 23. In a preferred arrangement, the openings are arranged uniformly annularly around the inner shell and uniformly spaced in an axial direction. The diameter or size of the. openings, however, becomes progressively larger at a greater distance from the exhaust passages 23. In other words, the diameter of the openings D is greater than the diameter of the openings D. This construction provides a controlled flow for controlled heat removal from the outer shell. This controlled flow permits a greater change in fluid temperature without objectionable variations in temperature across the roll face. This also permits a low rate of flow which is desirable.
The exhaust passages 23 are conveniently drilled to extend radially inwardly from the annular chamber 20 and communicate with an annular passage 24 leading out through the journal 16. A line 24a is connected to the annular passage and contains a pressure control valve 25. This is set at a low pressure sufficient only to prevent the drainage of coolant liquid from the annular chamber 20 when the roll stops. In other words, the valve 25 prevents drainage due to gravity.
Coolant is delivered to the inner chamber 21 within the inner shell through a line 26 connecting to a hollow coaxial passage 22 through the journal 16. Coolant is delivered through the line 26 by pump 27. Thus, the flow of coolant into and out of the roll is conveniently arranged through coaxially located passages.
For controlling the temperature of the outer roll shell, the temperature of the coolant may be measured such as by a device located at 28 in the line 24a. This coolant detection device may be connected to control the operation of the pump 27 so that coolant is delivered at a rate to maintain a uniform predetermined temperature for the roll cover 13.
FIG. 2 shows in somewhat greater detail the relative location of certain of the elements. The disk 14 is formed with a bevelled face 14a on its inner edge so that it coaxially seats the inner shell 18. The end of the inner shell 18a seats so as to prevent leakage of coolant. The disk head 14 has an annular surface 14b to provide a flow space for coolant flowing through the exhaust passage 23.
As shown in FIG. 2, the holes 19 in the inner shell are countersunk, as in 19a, from their outer surface to prevent clogging of the openings. v
The openings are so arranged, as above stated, by size so that a greater amount of fluid is passed across the inner surface of the outer shell for the longest distance between the large openings and the exhaust port, while a lesser amount flows from the inner chamber through smaller holes nearer to the exhaust port. This lesser amount of fluid remains in the heat transfer chamber for a shorter period of time. This results in a relatively even temperature level in the fluid across the entire roll face.
The annular coolant chamber must be maintained relatively thin and preferably on the order between one-eighth to. one-fourth inch thick. As an example of a size relationship which is well suited, is a chamber which is three-sixteenth inch radial dimension. The holes leading into the space are arranged sequentially larger away from the exhaust opening 23. For example, if five holes are used along the length of the roll shell, the holes may be on the order of 3/32, Vs, /32, 3/16 and 541 inch in diameter. The size of the inlet and exhaust passages are not critical, except they must be sufficiently large to carry maximum coolant flow, and an inlet pipe on the order of 1 inch is well suited for the above dimensioned openings. The exhaust ports may be on the order of inch diameter with a plurality of ports provided uniformly circumferentially spaced with 8 exhaust ports being used.
While the foregoing description refers to the delivery of coolant fluid, in order to carry away heat from the roll shell, it will be understood that the principles of the invention can fully be used for circulation of a heating liquid. Where the roll shell is to be heated a liquid will be circulated which is heated to a predetermined temperature to convey heat to the roll shell. It will be understood that the concepts of the invention herein disclosed are not to be limited to either heating or to cooling.
I claim as my invention:
1. A temperature controlled roll mechanism for a paper machine or the like comprising in combination:
a first roll having a roll shell with an inner rigid metal annular base and a covering of a composition having an upper temperature limit;
a second opposing heated roll forming a roll couple with the first roll and being heated to heat the outer layer of said first roll;
end journals for the first roll for supporting the roll for rotation;
an inner shell positioned coaxially within the outer shell and defining a thin annular chamber therebetween and forming a hollow fluid receiving inner chamber within the inner shell;
a plurality of axially spaced openings through said inner shell leading from said inner chamber to said annular chamber;
a coolant delivery mechanism connected to said inner chamber;
and a coolant exhaust passage connected to one end of said annular chamber receiving flow from said axially spaced openings so that fluid flows axially through the annular chamber to said exhaust passage.
2. A temperature controlled roll mechanism for a paper machine or the like constructed in accordance with claim 1:
wherein said openings are constructed so that a greater volume of flow passes from the inner chamber to the annular chamber at the end remote from said exhaust passage than at the end adjacent said exhaust passage.
3. A temperature controlled roll mechanism for a paper machine or the like constructed in accordance with claim 1:
wherein said openings are larger at the end of said inner shell remote from the exhaust passage than at the end adjacent said exhaust passage.
4. A temperature controlled roll mechanism for a paper machine or the like constructed in accordance I with claim 1:
including a pressure relief valve in said exhaust passage maintaining coolant within the annular chamber and preventing gravity drainage of the coolant from said annular chamber.
5. A temperature controlled roll mechanism for a paper machine or the like constructed in accordance with claim 1:
wherein said coolant delivery mechanism includes an axial flow passage into said inner shell coaxially arranged with said coolant exhaust passage.
6. A temperature controlled roll mechanism for a paper machine or the like constructed in accordance with claim 1:
wherein said journals are supported on circular disks positioned in each end of said roll shell.
7. A temperature controlled roll mechanism for a paper machine or the like comprising in combination:
means for delivering said fluid to the inner chamber of said inner shell;
and a fluid exhaust passage leading from one end of said annular chamber so that the fluid flows axially in the annular chamber to said one end.
8. A temperature controlled roll mechanism for a paper machine or the like constructed in accordance with claim 7:
wherein said openings are constructed for a greater volume of flow into said annular chamber at the end of the inner shell remote from the exhaust passage than adjacent the exhaust passage.
9. A temperature controlled roll mechanism for a paper machine or the like constructed in accordance with claim 7:
wherein said journal members have circular disks mounted within said outer roll shell with said exhaust passages being within one of said disks.
10. A temperature controlled roll mechanism for a paper machine or the like constructed in accordance with claim 1:
wherein said annular chamber has a radial dimension in the range of one-eighth to one-quarter inch. =l=