US3186063A - Method of constructing roll shells - Google Patents

Description

June 1, 1965 H. R. DOPP 3,186,063

METHOD OF CONSTRUCTING ROLL SHELLS Filed 001;. 2, 1961 3 Sheets-Sheet l I N VEN TOR. Homer Rea/yer 90 AT VORNEYS June 1, 1965 oPP METHOD OF CONSTRUGTING ROLL SHELLS S Sheets-Sheet 2 Filed Oct. 2, 1961 INVENTOR. b ome -fiaer 00,0; BY a"? ORNEYS June 1, 1965 H. R. DOPP 3,186,063

METHOD OF CONSTRUCTING ROLL SHELLS Filed Oct. 2. 1961 3 Sheets-Sheet 3 IN V EN TOR. flame od er 0% ATT( NEYS United States Patent METHOD OF CGNSIRUCTING RULE, SHELL$ Homer Rodger Dopp, 1835 Sherwood Drive, Beloit, Wis. Filed Oct. 2, 1961, Ser. No. 142,389 14 Claims. (Cl. 29-14%.4)

This invention relates to improvements in roll shells and methods of constructing the shells.

Roll shells and particularly shells for the drier rolls and large diameter king or finishing rolls to be used in papermaking machinery are frequently made by centrifugal casting, due to the resultant dense homogeneous castings free from air entrapment-s and porosity, and due to the fact the centrifugal casting process produces an end product which is dimensionally close to finished size so that little machining is required.

Such shells have been cast to maximum diameters of approximately 55 inches, but at larger diameters the centrifugal casting process becomes too complicated and expensive to be practical.

Roll shells of diameters in excess of 55 inches have been molded in a conventional manner by pouring the metal into the cylindrical space between the mold and core and by prefabricating cylindrical sections which have either been pre-cast or rolled out of metal plates, and

welding the sections together to the final cylindrical form.

In both of these prior methods the physical and mechanical properties of the centrifugal casting process are sacrificed and the resultant product is an inferior product over what could be obtained by centrifugal casting. Also where the shell is constructed of prefabricated sections, the sections must be machined to obtain the required welding faces and grooves, and it is not possible to maintain a uniform quality throughout the drum, thereby making it necessary to construct a heavier shell using more material than would be required with a centrifugal casting, in order that the shell may stand up. Even then the resultant shell is still subject to variationsin quality and is extremely difiicult to accurately finish to a uniform size.

A principal object. of the present invention is to cure the foregoing deficiencies in large diameter roll shells by providing a process for constructing roll shells of large diameters, having the quality and uniformity of centrifugal cast bodies. 7

A further object of the invention is to construct a prefabricated cylindrical body without losing any of the advantageouscharacteristics and physical and mechanical properties normally obtained by the centrifugal casting process. a

Still another object of the invention is to provide an improved method of forming large diameter shells having the physical and mechanical properties of centrifugal cast shells, in which two shells of different diameters smaller than the diameter-of the finished shell are cast centrifugally and are then cut into sections, in which the radius of each section is increased to the required radius of the finished shell, and the sections are assembled and welded together.

A still further object of the invention is to provide an improved form of large diameter roll shell having the physical andmechanical properties of a centrifugally cast shell, in which the shell is formed from a plurality of centrifugally cast sections, cast at smaller diameters than the diameter of the finished shell, and expanded to the diameter of the finished shell and welded together to the form of the desired completed shell.

These and other objects of the invention will appear from time to time as the following speecification proceeds and with reference to the accampanying drawings where- FIGURE 1 is an end view of a centrifugally cast shell of one diameter;

FIGURE 2 is an end view of a second centrifugally cast shell of a larger diameter;

FIGURE 3 is a fragmentary diagrammatic view showing one end portion of one form of shell, chucked for cutting the shell longitudinally;

FIGURE 4 is an end view of a complete large diameter shell, showing the sections of two shells welded together after having been formed to the required radius of the large diameter shell;

FIGURE 5 is a fragmentary side view of the shell shown in FIGURE 4;

FIGURE 6 is a diagrammatic sectional view of a fragment of a shell showing the fragment of the shell within a sand mold, formed to form a weldinggroove in the shell, along which the shell may be cut; 7

FIGURE 7 is a diagrammatic fragmentary view of a fragment of a shell, showing the shell cut along the center of the welding groove; 7

FIGURE 8 is a diagrammatic sectional view taken through a section of a shell, showing the sections of the shell welded together;

FIGURE 9 is a perspective view of a large diameter finished shell, showing a modified form in which the shell may be fabricated;

FIGURE 10 is a view of small diameter centrifugally cast shell showing the line of cutting of the shell, prior to expansion and assembly of the shell with another spirally cut and expanded shell;

FIGURE 11 is a perspective view of a small diameter spirally cut centrifugally cast section of a shell expanded to the diameter of the finished shell;

FIGURES 12 and 13 are side views of two shells of the same diameter, to be cut in wedge shaped patterns and expanded and assembled to a larger diameter shell;

FIGURE 14 is side view of a completed large diameter shell formed from the wedge shaped and expanded sections formed from the shells of FIGURES 12 and 13;

FIGURE 15 is an enlarged fragmentary view illustrating the welding of the shell shown in FIGURE 14;

FIGURE 16 is a longitudinal sectional view taken through a completed roll showing a roll of a type used in a paper machine drier and illustrating the method in which the shell is mounted on the end heads of the roll; and

FIGURES 17 and 18 are fragmentary sectional views showing alternate forms for providing flanges on the ends of shells for bolting or otherwise mounting the shells to the end heads therefor, to form a drum.

In the embodiment of the invention illustrated in FIG- URES 1, 2, 3, 4 and 5 of the drawings, I have shown a shell A of the radius R and a shell B of a radius R The shells A and B are centrifugally cast shells and may be cast from bronze, iron or any other material commonly used in the manufacture of paper machine rolls and roughly machined inside and outside, if desired. Due to its high thermal c.onductivity,hbronze is a preferred material for rolls engaged by doctor blades for maintaining a coating to a predetermined thickness or for maintaining the surface of the roll clean.

The shell A is shown as being divided into sections 1, 2, 3 and 4. The shell B is shown as being divided into sections 5, 6, 7, and 8. The shells A and B are then cut along spaced radial dividing lines extending longitudinally of the two shells to form a plurality of shell sections. The shell sections are then each expanded to an increased radius in a press or like tool exerting pressure on the concave walls of the sections to form sections to conform to the diameter of the completed large diameter shell C,

.as shown in FIGURE 4. The centrifugally cast shell sections may then be beveled along opposite sides thereof to form welding grooves when the sections are assembled.

The sections may then be assembled on a fixture and welded together to the form shown in FIGURE 4.

In FIGURE 3 I have shown a method in which the .shells may be supported prior'to cutting. As shown in this figure, the shells may be centrifugally cast to a greater length than the desired length of a completed shell. They may then be mounted on chucks at their opposite ends engaging the base of the shell on end portions 11 of the shell, that will not be cut. The shell may then be longitudinally cut by sawing or burning as indicated by reference characters 12. The shell segments may then be cut to length by sawing or burning inwardly of the ends of the shell, leaving the oversize end portions 11 of the shell in their cylindrical form. The oversize end portions 11 may be of a minimum width equal to the thickness of the wall of the shell. A width of one and one half times the thickness of the wall of the shell is, however, desirable for handling purposes.

Shell sections may also be formed by cutting or sawing slots along the lines 12, 12 in FIGURE 3 and by cutting the end portions 11 from opposite ends of the shell. The shell sections may then be gradually expanded in a press or the like to the required radius of the completed shell.

'Other shell sections may be formed in the manner just described, and the expanded shell sections so formed may then be assembled on a fixture and welded together. It is, of course, obvious that the width of the slot may be selected to avoid waste.

The shell just described, formed by the method of the invention has the physical and mechanical properties of centrifugally cast shells, and is superior in quality to large diameter shells formed by ordinary sand casting or by welding of sheet metal segments together, and is far more economical and practical to manufacture than if a shell of the same diameter were manufactured by centrifugal casting processes.

In FIGURES 6, 7 and 8 I illustrate a manner in which welding grooves may be formed along the adjacent edges of the assembled shell sections during the centrifugal casting process. FIGURE 6 diagrammatically shows a fragment of a shell segment 15 in section and diagrammatically shows a section of a sand mold 16. The sand mold 16 has inwardly extending arcuate ridges extending longitudinally therealong in registry with the locations of the cuts required to sever the small diameter shells into sections. The ridges 17 form arcuate depressions or recesses 19 in the centrifugally cast shell. The centrifugally cast shell may then be cut longitudinally along the centers of the recesses 19, the recessed portions extending along the adjacent edges of the shell sections when assembled, to form welding grooves. In FIGURE 8 two adjacent sections are shown as being welded together by welding material 21 in the molded welding grooves and are shown as being reinforced by a reinforcing plate 22 extending along the inside of the welded joint.

It should here be understood that while I have described the roll as formed from centrifugally cast shells of diiferent diameters, they may be formedfrom centrifugally cast shells of the same diameter, depending upon the required diameter of the final shell. The shells are preferably made from centrifugally cast cylinders of different diameters to provide the required material for a complete drum from two cylinders with no waste, and where two cylinders of the same diameter may furnish the material for a complete shell, the two cylinders may be used.

In the modified form of the invention shown in FIG- URES 9, l0 and 11, a centrifugally cast shell 23 of a smaller diameter than the diameter of the completed shell is out along the helical lines indicated in FIGURE 10. The shell sections are then opened and expanded to the required diameter of the completed shell. A second centrifugally cast shell of the same diameter as the shell 23 may then be cut along the same helical lines indicated in FIGURE 10 and opened to the diameter of the completed shell. The expanded shell sections will have opposite tapered end portions and widened intermediate portions and may then be assembled on a fixture with the tapered end portions extending from the widened portions so the widened portion of one shell section will face the widened portion of the next adjacent shell section and so the opposite ends of the assembled shell sections will be perpendicular to the cylindrical wall thereof. The assembled shell sections may then be welded together to form a larger diameter shell 24.

While the cylinder shown in FIGURE 10 is shown as being cut along a helix to open to a helix of the diameter of the completed shell, similar results can be obtained by cutting along a part of a helix and the cylinders may be out along helixes of various desired pitches and the sections when assembled to the required diameter may be arranged in side by side relation with respect to each other to form a cylinder of the required length and diameter.

In this form of the invention a helical groove (not shown) along which the shell is to be cut may be cast in the shell in the form of a helical U-shaped recess extending along the shell in the manner illustrated in FIGURE 6, to provide a welding groove when the shells are assembled for welding.

A cylinder formed from welded centrifugally cast shell sections cut along helixes and expanded, provides the uniform surface required for paper machine rolls, in which the cylinders are in constant rolling contact with each other. With such a shell the biting of the doctor blade in the roll, which may be caused by longitudinal ridges formed in the surface of the shell, after wear, due to the difference in the material of the shell and the Welding material, is obviated.

In FIGURES 12 and 13, I have diagrammatically shown two shells 25 out into tapered or wedge shaped sections after machining the inside of the shell. In this form of the invention the radii of the wedge shaped sections are increased to the inside radius of the completed shell. The shell sections are then assembled in a fixture as shown in FIGURE 14, and welded along the juncture of the sections with each other to form a large diameter shell 26.

FIGURE 15 illustrates the welding of the wedge shaped sections together. The welding grooves either may be machined on the wedge shaped sections, or may be formed by casting recesses along the lines of cutting of the sections as in FIGURES 6, 7 and 8.

In this form of shell, like the form of shell illustrated in FIGURE 9, a doctor blade or another roll working in conjunction with the shell will always be in contact with a portion of the weld, with the result that the possibiliy of the doctor blade digging into the welds will be materially reduced and the vibration caused by the welds where another roll works with the shell, will be eliminated.

In FIGURE 16 I have shown one manner in which a shell 30 may be mounted on end heads 31, to form a roll or drum for a paper machine drier, such as is shown and described in Patent No. 3,089,252, which issued to Robert A. Daane and Edgar J. Justus on May 14, 1963. As shown in FIGURE 16, a bolting ring 32, extends along the end and inner periphery of the shell 30 for a short portion of the length of the shell and is welded thereto at 3% and 34. The head 31 may then be attached to the bolting ring 32 as by cap screws or nuts and bolts.

In FIGURE 17 an annular bolting ring 35 extends inwardly of the margin of a shell 36 and is welded thereto at 37. The drum head-may then be bolted to the annular bolting ring 35.

In FIGURE 18 the bolting ring is L-shaped in cross section and has a cylindrical portion 39 abutting the end of a cylindrical shell 49 and of the same diameter as the shell, andwelded thereto on the inner and outer sides of the shell, as indicated by reference characters 41 and 42 respectively. The cylindrical portion 39 has an inwardly extending flanged portion 43 forming a bolting ring for bolting a head to the shell.

While I have herein shown and described several forms in which my invention may be embodied, it may readily by understood that variations and modifications in the invention may be attained Without departing from the spirit and scope of the novel concepts thereof as defined by the claims appended hereto.

I claim as my invention:

1. The method of constructing large diameter roll shells which comprises the steps of casting two cylinders of smaller radii than the required radius of a finished shell, cutting each cylinder into at least one shell section, in-

creasing the radii of the shell sections to the required radius of the finished shell, and then welding the sections to the required radius.

2. The method of constructing roll shells which comprises the steps of casting two cylinders of smaller radii than the required radius of a finished shell, roughly machining the cylinders to size, cutting the cylinders into a plurality of shell sections, increasing the radii of the sections to the required radius of a finished shell, assembling the shell sections to the required diameter of the finished shell and then welding the sections together.

3. The method of constructing roll shells which comprises the steps of contrifugally casting two cylinders of smaller radii than the radius of a finished shell, cutting the two cylinders into at least two shell sections, increasing the radii of the sections to the required radius of the finished shell and then assembling and welding the sections to the required diameter.

4. The method of constructing roll shells which comprises the steps of contrifugally casting two cylinders of smaller radii than the radius of a finished shell, cutting the cylinders longitudinally into a plurality of sections, increasing the radii of the sections to the required radius of the finished shell, assembling the sections into a cylindrical form and then welding the sections to the required diameter of the finished shell.

5. The method of constructing roll shells which comprises the steps of centrifugally casting two cylinders of smaller diameters than the required diameter of the finished shell, casting grooves in the periphery of each cylinder during the casting operation, cutting the two cylinders along the centers of the grooves into at least two shell sections, increasing the radii of the sections to the required radius of the finished shell, then assembling the section-s to a cylindrical form and welding the sections together.

6. The method of constructing roll shells which comprises the steps of centrifugally casting a plurality of cylindrical shells of smaller diameters than the required diameter of the finished shell and casting equally spaced grooves to extend along the periphery of each shell during the casting operation, roughly machining the shells to size, cutting the shells along the centers of the grooves into a plurality of sections, increasing the radii of the sections to the required radius of the finished shell, assembling the sections into a cylindrical form of substantially the inside diameter of the finished shell, and then welding the sections along the adjacent grooved portions thereof, to form a shell of the required diameter.

7. In a method of constructing roll shells, the steps 6 of centrifugally casting a plurality of cylinders'of smaller diameter than the required diameter of a finished shell and, longer than the length of a finished shell, chucking the ends of the cylinders, longitudinally cutting the cylinders between the chucked ends thereof into sections of equal width, increasing the radii of the sections to the required radius of the finished shell, assembling the sections to a cylindrical form of the diameter of the finished shell, and then welding the'sections together.

8. A method of constructing roll shells comprisingthe steps of centrifugally casting a plurality of cylinders of smaller diameters than the required diameter of the finished shell, cutting a slot in each cylinder for the length thereof, expanding each slotted cylinder to shell sections having radii equal to the required radius of the finished shell, assembling the expanded shell sections to a cylindrical form, and then welding the sections together.

9. In a method of constructing roll shells, the steps of centrifugally casting a plurality of cylinders of smaller diameters than the required diameter of a finished shell and longer than the length of a finished shell, cutting a slot in each cylinder between the ends thereof, cutting the ends from each cylinder to form a plurality of shell sections, expanding each shell section to the required radius of the finished shell, assembling the expanded shell sections to a cylindrical form, and then welding the sections together.

10. In a method of constructing roll shells, the steps of centrifugally casting a plurality of cylinders, machining at least the inner peripheries of the cylinders, severing each cylinder along helical paths into atleast two sections, expanding the severed sections to the required inside radius of the finished shell, assembling the expanded spirally severed sections to form a cylindrical shell, and then welding the sections together.

11.' In a method of constructing roll shells, the steps of centrifugally casting a plurality of cylinders and during casting thereof casting helical grooves therein, severing each cylinder into at least two sections along the centers of the helical grooves, expanding the severed sections to the diameter of the finished shell, assembling the severed sections to form a cylinder having an inside diameter equal to the required inside diameter of the finished shell, then welding the sections along the adjacent grooved portions thereof.

12. In a method of constructing roll shells, the steps of centritugally casting a plurality of cylinders of the same diameter, machining at least the insides of the cylinders to size, cutting the cylinders generally longitudinally thereof into a plurality of wedge shaped sections, increasing the radii of the sections so cut to the required radius of the finished shell, then assembling the sections cut into a cylindrical shell having an inside diameter equal to the required diameter of the finished shell, and then welding the assembled sections together.

13. In a method of constructing roll shells, the steps of centrifugally casting a plurality of cylinders of the same diameter, having grooves formed in the outer peripheries thereof extending longitudinally thereof and angularly along the faces thereof to divide the cylinders into a plurality of wedge shaped sections, cutting the cylinders along the centers of the grooved portions thereof to form a plurality of wedge shaped sections, increasing the radii of the sections to the required radius of the finished shell, assembling the sections to the required diameter of the finished shell with the grooved portion of one section extending along the grooved portion of the other section, and then welding the sections along the grooved portions thereof.

14. The method of constructing roll shells which comprises the steps of centrifugally casting two cylinders of smaller diameters than the diameter of a finished shell,

cutting the two cylinders into at least two shell sections, expanding the shell sections to conform to arcs struck Ifrom radii equal to the radius of the finished shell, beveling the shell sections along opposite sides thereof to form welding grooves when the sections are assembled, assembling the sections to form a cylinder having a diameter equal to the diameter of the finished shell, and then Welding the sections along the welding grooves formed by the adjacent beveled sides of the sections.

References Cited by the Examiner UNITED STATES PATENTS Caas 138-154 X Meneely 138-154 X Zerbe.

Watson.

Hodge.

Shank 29-1484 X Carstens 29-463 WALTER A. SCHEEL, Primary Examiner. FRANK H. BRONAUGH, JOSEPH BEIN, Examiners.

Claims (1)

1. THE METHOD OF CONSTRUCTING LARGE DIAMETER ROLL SHELLS WHICH COMPRISES THE STEPS OF CASTING TWO CYLINDERS OF SMALLER RADII THAN THE REQUIRED RADIUS OF A FINISHED SHELL, CUTTING EACH CYLINDER INTO AT LEAST ON SHELL SCTION, INCREASING THE RADII OF THE SHELL SECTIONS TO THE REQUIRED RADIUS OF THE FINISHED SHELL, AND THEN WELDING THE SECTIONS TO THE REQUIRED RADIUS.

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