US1742454A - Method of making rolls - Google Patents

Description

Patented `an. 7, 1,930

UNITED STATES PATENT OFFICE GEORGE N. VAN DERHOFROF MISHAWAKA, INDIANA, ASSIGNOR TO DODGE MANUFAC- TURING CORPORATION, OF MISHAWAKA, INDIANA, A CORPORATION OIE" DELA.-

WARE

METHOD 0F MAKING ROLLS i Original application filed June 22, 1927, Serial No. 200,566. Divided and this Serial No. 293,272.

This invention relates to the manufacture of rolls such as conveyor rolls, and aims to provide a practicable method of making a hollow cast iron roll which will be substantially axially balanced, obviating the necessity for expensive and laborious balancing operation required in themanufacture of present day rolls of this character.

This application is a division of my earlier filed application Serial No. 200,566, filed June 22, 19277 in which I claim'as `an article of manufacture a roll made in accordance with the present invention.

The above and other objects will be more fully apparent and set forth in the following specification and illustrated in the accompanying drawing, in which Fig. 1 is a longitudinal secton through a roll made according to my invention, the supporting means and adjacent roll ends being illustrated in elevation; y

Fig. 2 is a diagrammatic section of a portion of a mold and core employed in my method; and y Fig. 3 is a longitudinal section through the end of a roll cast according to my process.

Figs. 2 and 3 illustrate in an exaggerated manner the effect of the failure to properly center the core in the mold, which failure produces an unbalanced casting.

10 indicates the roll generally, preferably cast of ironJ comprisingr a hollow cylindrical body having the extended rim 11 With the concaved webs 12 at each end, the webs being imperforate in the form illustrated except for central axle openings.

In casting the roll the hollow interior is formed by use of a core 14 cylindrical in shape and having at each end a projecting end portion 15 connected with the main body of the core by the narrow neck 16 which forms the bearing recesses 13 in the roll web 12.

In forming the core the projecting ends 15 are made exactly co-axial with the axis of the main body of the core 14 and are provided with a convex face which forms the dished or concave surface 17 of the roll web (see Figs. 2 and 3). This surface 17 is therefore coaxial with the core body 14 and therefore with the cylindrical inner surface 18 of the application filed J' uly 16, 1928.

roll. The core is readily and accurately positioned in the mold by means of the projecting end portions 15 which support the body of the core 14 in spacedrelation from the surrounding mold to effect the casting of the Wall and the rim 11 of the roller 10.

If the core be improperly positioned in the mold or if it be displaced during the formation of the mold so that its longitudinal axis does not exactly coincide with the axis of the cylindrical surface 21 of the mold, the rim of the casting will be of non-uniform thickness, as illustrated in exaggerated manner by the dot anddash line in Figs. `2 and 3. Obviously, this results in an unbalanced roll. Notwithstanding this defect in a roll, the su:` faces 17 of the casting will always be co-axial with the interior cylindrical wall `surface 18.

In practicing my method, after the casting has been removed from the mold and the intcrior thereof cleaned out, the casting is mounted in anishing machine (such as a boring mill or lathe) by engagement ofthe machine with the concave surface or surfaces 17 so that the operating axis of the machine Will be co-axial with the concave surfaces 17 and therefore co-axial with the cylindrical inner wall 18. Utilizing this means of centering the roll, they bearing recesses 13 and the outer surface ofthe rim may be finished by any process such as boring, turning or grinding until the outer surface of the roll is fully concentric with'the operating axis of the machine. f

For example, the bearing recesses 13 at the endsv of the roll may be bored out and reamed to exact size and accurately centered with reference to the axis of the cylindrical inner surface 18. In this case such operation includes the finishing and centering of the surfaces 22 and 23 of the bearing recesses. By this process offinishing, the exact longitudinal alignment of the opposite bearing recesses is insured.

While the roll is thus centered or by centering it by the use of the accurately centered bearing recesses, the outer surface of the roll is finished by grinding, for example, until such surface is fully or substantially concentric with the inner surface 18. This operation obviously cures the non-uniformity of the metal distribution in the rim of the roller, as illustrated in Figs. 2 and 3. The grinding or finishing may be continued, if desired, to bring the thickness of the rim 11 to any desired measurement or to reduce the weight of the roll to a point consistent with the strength requirement.

From the foregoing, it will be seen that a hollow cast iron rollhaving integral heads and hubs, provided in this instance by the Webs 12 set inwardly from the ends of the roll and formed with inwardly extending hub portions in which the bearing recesses 1.3 are provided, is cast on a cylindrical core having annular recesses arranged and shaped for casting the said heads and hubs. The outer walls of these recesses are on the core extensions 15, thus providing mold surfaces for shaping the roll ends exteriorly, which surfaces are coaxial with and in fixed relation to the main body of the core and are formed to provide the roll ends with chucking surfaces, typified by the concaved surfaces 17, which define or locate a center coincident with the core axis or with the axis of the interior cylindrical surface -of the roll cast on such core. For at least the first machining operation, the roll is mounted by chueking the said chucking surfaces, thus locating the working axis for the machining operation coincidentally with the axis of the interior cylindrical surface of the roll, and insuring the machining truly concentrically with said interior cylindrical surface. In practice, the roll being centered with reference to said interior cylindrical surface by chucking the said surfaces 17, the

first machining operation is preferably the boring and, finishing of the bearing recesses 13 in the hubs; and for the subsequent machining operations the roll may be chucked either by the said surfaces 17 or by the bearing recesses accurately centered in relation thereto, and the roll may be exteri-orly machined in true concentricity with its interior surface, as before explained.

By means of this process it is possible to make a roll of minimum rim thickness without running the risk of developing any regions which are of less than minimum thickness; and the tolerance usually allowed for defects and inaccurate casting may be considerably reduced. It also eliminates the necessity for subsequent balancing adjustment which is laborious and consequently an expensive operation.

By the above described process, all parts of the roll are finished so as to be co-axial with the axis 0f the interior cylindrical surface of the roll and are rendered uniform in dimension so as to effect an axial balancing of the roll and to insure that the axis of rota- Vtion of the roll will coincide with the axis of the inner and outer cylindrical surfaces of the roll. This is particularly advantageous in conveyor rolls and the like, where with long conveyor belts the friction of a large number of unbalanced rolls on the expensive belt would not only cause a serious wearing of the belt, but would require a much stronger belt because of the increase in tension on the belt due to the unbalanced rolls. Since a conveyor belt is costly and a very large item of expense in a conveyor system of this character, smoothly running and well balanced rolls permita substantial reduction in belt thickness and therefore in cost of the belt.

A cast roll of this charatcer is well suited to resist the destructive wear which often results in other types of rolls, particularly Where the conveyor handles abrasive material.

ln the form illustrated, the roll is provided with roller bearings mounted in the bearing recesses adjacent each end of the rolls. .Such bearings comprise the cup 24 having a tapered surface and `advantageously forced into the recess 13 by a press lit, and the cone having a tapered bearing surface, the cone being forced by a press fit on the roll shaft 26. Between the rings are series of tapered bearing rollers 27 held uniformly separated by the cage 28. The exact alignment of the bearing recesses 13 makes it possible to locate the bearing cup axis co-axial with the bearing cone land shaft axis, thereby insuring proper operation of the bearings. Surrounding the shaft and spaced therefrom is a. grease tube 29 extending through the roll and having its ends tightly beaded at 30 to the flanges 31 projecting inwardly adjacent the inner edge of the bearing),` recess 13. The beading operation may place the tube in sufficient tension to maintain a tight joint throughout the life of the roll. Tube 29 serves not only a grease reservoir but seals the interior 32 of the casting from any communication with either the grease space or the bearings. This is advantageous in a hollow casting of this character, because of the possibility that in practice, all core sand or other abrasive material may not be removed from the interior of the casting.

The roll is supported by end pieces 33 titting over the opposite ends of the roll sha-ft 26 and mounted in supporting members 3l. In thepresent case the stems of the end pieces 33 enter fairly closely fitted open recesses 35 in the supports 34 which hold the end pieces suliieiently tightly but enable a roll to be removed simply by liftingl it until the end pieces clear the recesses and supports. The rolls are supplied with lubricant (which need be replenished only at long intervals) through a lubricant tube 3G (having an appropriate fitting 37 at the end) by means of which lubricant may be forced through a registering opening in the end piece 33 and through an opening 38 into the interior 39 of the shaft (which is made hollow for this purpose). The lubricant pipe 36 extends downwardly at an angle from the end piece to a point which will permit a lubricant supply means to be attached without interrupting the operation of the conveyor. The interior of the roll shaft communicates through openings 40 with the space immediately adjacent the bearing. Surplus lubricant may be accumulated not only on the interior of the shaft but in the grease tube 29 surrounding the shaft. j

A vgrease `pipe may be applied to whichever end piece 38 is most convenient. In ordinary practice it is necessary to employ only one grease supply pipe per roll, the passage in the other end piece being closed by'an ordinary plug.

Grease sealing means represented by a labyrinth packing (providing successive restricted and enlarged passages) are mounted on each shaft at the outer ends of the bearing. In the present case the labyrinth packing comprises a disk 4l (providing adjacent its outer edges two constricted passages 42 and an intermediate enlarged space) and an outer plate 43, the flange 44 of which enters a circular groove in the end web of the casting and providing further restricted passages which resist escape of grease. A collar 45 comprising an annular flanged plate, fits in the bearing recess adjacent the bearing and provides an additional restricted passage between its inner edge and the ring 25. The grease seal above described effectively prevents the escape of grease.

Adjacent the grease hole 38 in the shaft is a circumferential recess 46 in the shaft 26 which provides a passage for the travel of grease in the event the hole 39 does not register fully with the end of the grease pipe 36. A set screw 47 in the end piece engages the shaft 26 after the hole 38 has been brought into register with the grease hole in the end piece and prevents relative rotation. A fastening and adjusting bolt 48 is screwed into each end of the shaft and is provided with a washer 49 engaging the outer face of the end piece. This bolt may be employed to adjust Vthe bearing to take up for wear by forcing the inner bearing ring 25 along the shaft relative to the outer ring 24. A locking member in the form of a washer having bendable lugs 50 thereon surrounds the bolt 48 and prevents its rotation relative to the end piece. `The locking member has an extension 5l extending into a recess 52 in the end piece so as to prevent rotation of the locking member relative to the end piece. The bendable lugs 50 on the locking member are angularly spaced a distance corresponding to the angular separation of the faces on the head of a hexagonal bolt, for example, so that the lugs may be bent to bear against such faces.

Obviously the invention is'not limited to the details of the illustrative embodiment thereof herein disclosed, since such details may be variously modified. Moreover, it is not'indispensable that all features of the invention be used conjointly, since certain features may be advantageously used (without others) in other methods and combinations.

The mechanical construction of the roll herein described, and the conveyor-belt supporting structure comprising the rolls, is the subject-matter of my copending application `Serial No. 367,357, filed May 3l, 1929, being adivision of the present application.

Having described one embodiment of my invention, I claim:

1. The method of making axially balanced hollow cast iron rolls which is characterized by casting the roll with a cylindrical interior surface and with end chucking surfaces coaxial therewith, centering the cast roll by the said chucking surfaces on an axis which coincides with the axis of the interior surface of the roll, and then finishing bearing recesses at the ends of the roll by a machining operation about said axis so that the axis of the bearings will coincide with said axis.

2. The method of making axially balanced hollow cast iron rolls which is characterized by casting the roll with a cylindrical interior surface and with end chucking surfaces coaxial therewith, centering the cast roll by the said chucking surfaces on an axis which coincides with the axis of the interior surface of the roll, finishingy bearing recesses at the ends of the roll by operation about such axis so that the axis of the bearings will coincide with said axis, and then mounting the roll by such finished bearing recesses and finishing the outer surface of the roll about such axis so that the roll rim will be of uniform thickness.

8. The method of making hollow cast rolls of the charactervdescribed which is characterized `by ycasting the roll with a surface accessible externally of the roll having a definite relation with the axis of the interior cylindrical surface of the roll, then mounting said roll by such externally accessible surface on an axis which coincides with said axis of said interior" surface, whereby the exterior cylindrical surface of the roll may be finished co-axially with said interior surface.

4. The method of making hollow cast rolls of the character described which is characterized by casting the roll with surfaces accessible externally of the roll co-axial with the axis of the interior cylindrical surface of the roll, then mounting said roll by means of such externally accessible surfaces on an axis which coincides with the axis of said V interior surface, whereby the exterior cylinrical surface of the roll may be finished co-axial with said interior surface.

5. The method of making hollow cast rolls of the character described which is characterized by casting the roll with surfaces accessible externally of the roll co-axial with the axis of the interior cylindrical surface of the roll, then mounting said roll by means of such externally accessible surfaces on an axis which coincides with the axis of said interior surface, and then finishing bearing recesses at the ends of said roll co-axial with said axis.

6. The method of making hollow cast rolls of the character described which is characterized by casting the roll with surfaces accessible externally of the roll co-axial with the axis of the interior cylindrical surface of the roll, mounting Said roll by means of such externally accessible surfaces on an axis which coincides with the axis of said interior surface, finished bearing recesses at the ends of said roll co-axial with said axis, and then mounting said roll on the axis of said finished bearing recesses and finishing the exterior cylindrical surface of the roll to provide the roll with a rim of uniform thickness.

7. The method of making hollow cast iron rolls of the kind described which is characterized by casting said rolls with a cylindrical interior surface and concave ends of circular cross-section and co-axial with said cylindrical interior surface, and then mounting said rolls by engagement with said concave ends on an axis coincident with the axis of said cylindrical interior surface, whereby the roll may be finished on the exterior in true concentricity with said interior surface.

8. The method of making hollow cast rolls of the character described which is characterized by providing a cylindrical core to form the hollow interior of the casting and shaping the core to provide a surface on the exterior of the casting which has a definite relation to the axis of the interior cylindrical surface of the casting, and then mounting said casting by means of said surface in afinishing machine so that the axis of the finishing inachine will be co-axial with the axis of said interior cylindrical surface, and then finishing the outer cylindrical surface of said roll so that it will be co-axial with said interior surface.

9. The method of making an axially balanced hollow cylindrical casting which is characterized by providing on the core which forms the hollow interior, an exterior portion which is co-axial with the axis of the core so that the casting will be provided on its exterior adjacent an end with a surface of circular.cross-section which is co-axial with the interior cylindrical surface of the cylinder; then mounting said casting in a finishing machine by means of said exterior surface so that the axis of operation of the machine will be co-axial with the axis of the interior surface of the cylinder; and then finishing the outer cylindrical surface of the cylinder so that it will be co-axial with the axis of said interior surface, whereby the wall of Said cylinder will be of uniform thickness and will be axially balanced.

lO. rI`he method of making an axially balanced hollow roll with bearing webs at the ends which is characterized by casting the roll with a core having a portion exterior of said roll which is co-axial with the portion which cores out the interior of the casting and which forms a concave surface of circular cross-section exterior to the end web, then centering said casting in a finishing machine by means of said concave surface so that the axis of operation of the machine will be co-axial with the axis of the cylindrical interior surface of said casting, then finishing bearing recesses in said webs so that they will all be co-axial with the axis of said interior cylindrical surface, and then by mounting the roll on the axis of the finished bearing recesses finishing the exterior surface of said roll co-axially with the interior surface so that the roll rim will be of uniform thickness.

ll. The method of making an axially balanced hollow roll with bearing webs at the ends which is characterized by casting the roll with a core having a portion exterior of said roll which is co-axial with the portion which cores out the interior of the casting and which forms a concave surface of circular cross-section exterior to the end web, then centering said casting in a finishing machine by means of said concave surface so that the axis of operation of the machine will be co-axial with the axis of the cylindrical interior surface of said casting, and then finishing the bearing portions of said end webs so that said bearing portions will be co-axial with the of said interior cylindrical surface.

12. The improved method of manufacturing a hollow cast iron roll which is characterized by casting the roll with a cylindrical interior surface and with end chucking surfaces locating a center coincident with the axis of the said cylindrical interior surface, mounting the roll for a machining operation by chucking it by the said chucking surfaces, thereby locating the axis for the machining operation coincidentally with the axis of said cylindrical interior surface, and conducting trie machining operation about the said axis.

13. The improved method of manufacturing a holiow cast iron roll having integral heads and hubs, which is characterized by providing a cylindrical core with annular recesses arranged and shaped for casting the said heads and hubs, forming the said recesses to provide the roll heads with exterior chucking surfaces centered coincidentally with the axis of the core, casting the roll on said core, mounting the roll for a machining' operation by chucking it by the said chucking surfaces, thereby locating the working axis for the machining operation coincidentally with the axis of the cylindrical interior surface of the roll, and performing the said machining operation about the said axis. Y

14. The improvement in the art o casting a hollow roll, which consists in casting the roll on a hollow core while casting heads and hubs integral with the roll between mold surfaces in fixed relation with the core and formed to provide the roll heads with chucking surfaces centered coincidentally with the core axis, which surfaces may be availed of for centering the roll for machining.

15. The improvement in the meth-od of making a hollow cast roll, which is characterized by coring the roll to provide a cylindrical interior surface while shaping the ends of the roll casting by molding surfaces in iXed relation and coaxial with the core and formed to provide the ends of the roll with surfaces which may be availed oii' for centering the roll for a machining operation.

In testimony whereof, I have signed my name to this specification.

GEORGE N. VAN DERHOEF.

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