US2215424A - Roll - Google Patents

Description

Sept. 17, 1940. F, w g- 2,215,424

ROLL

Filed April 18, 1938 Patentedjsept. 17, 1940 uuirso {STATES PATENT OFFICE 7 Application April 1 8, 1938, Serial No. 202,696

Germany December 28 1936 1 Claim.

, The present invention relates to rolls and a process for making such rolls, which may be used in rolling mills for reducing metal bars to thin sheets or strips. It is more particularly 8 concerned with composite support or backing rolls, for example for four high rolling mills and also with rollers for the rubber, dye, and paper industries and for similar purposes, which have a harder shell or outer layer, which forms the operating surface and is supported with a shrink- 1 the shaft or spindle. It must therefore expand at each cycle of heating and cooling, even at age fit on a more elastic shaft or spindle.

The invention has among its objects toprovide a roll of this type which is cheap to manufacture and is so constructed that the shell cannot creep along the shaft or move thereon, and thus give a better formed roll, which combines the known advantages of'this type of roll with the advantages of a solid roll While avoiding their defects. Further the invention aims at, providing an improvement in the production of rolls of this kind. The nature of this invention and its particular advantages and novel features will be seen from the detailed description in conjunction with the appended drawing, in which, I

' Figs. 1, 2 and 3 show in section along the longitudinal axis, three examples of how the invention can be applied in the production of such rolls. 80 Referring to Fig. 1 of the drawing a roll comprises a shaft or spindle a and a sleeve or shell 17 concentric thereon. The part of the shaft on which the sleeve or shell is mounted is provided with a concentric enlargement c. The bore of the sleeve is correspondingly enlarged at the same point in order to take the enlargement c. The sleeve is slid on from the end opposite the enlargement 0 until it comes into contact with the enlargement. 4 The principal problem with such composite "rolls is to prevent the sleeve or shell from either moving in the axial direction, or creeping along the shaft or spindle in use, where the sleeve or shell is more strongly heated and expands more. Previously an attempt has been made to avoid this wandering or creeping by forcing the sleeve or shell with a shrinkage fit- 111 the usual manner-on the shaft or spindle up to a stop on the latter, but in this case. either on the shaft or in the bore of the sleeve at the centre of the length of the latter a projection was provided of about a third to a half of the length of the sleeve and of such size that the shrinkage pressure in the region of this portion is two or three times greater than at the ends. Apart from the higher shrinkage pressure at the centre of the sleeve, on shrinkage the projection on the shaft or spindle is forced into the wall of the sleeve or the projection in the bore of the latter is forcedinto the shaft or spindle in such manner I that it is securelyheld inboth directions.

It is however erroneous to assume that-the ,sleeve can no longer wander on the shaft under all circumstances. It is obvious that, since it is more strongly heated, it must expand more than to its most rigid central portion and on both sides thereof and contract again on cooling and it must therefore slide back and forth on the shaft spinll dle. This occurs with a fairly high pressure between the two parts, and therefore probably with a rubbing action which 'is all the greater, the

greater is the local pressure, and is greatest at the centre'of the sleeve or shell and thereby the m softer of the two parts is worn away gradually. Whetherthe centre of the sleeve remains seated in place or wanders thus depends on the conditions, for example onthe lateral roll pressure,. on the even distribution of the heat along the 25 length of the sleeve, on the regularity of the original shrinkage pressure, and so on. The shrinkagepressure can even fall so far at the central part of the sleeve that finally creeping of the sleeve or shell along the shaft or spindle 30 is possible. This defect cannot be wholly overcome by making the projection on the shaft or in the bore of the sleeve higher, as high as the shrinkage of the sleeve or shell permits, and by providing agroove of corresponding depth in 35 the bore of the latter-0r converselyin order to obtain a greater support edge at this strengthened intermediate part, with the same shrinkage pressure. By these means the difference in the heat expansion of the sleeve and shaft are not overcome. One must make the recess in the bore of the sleeve or in the shaft which cooperates with the projection in the other part at least as much wider as the expansion of the corresponding part of the length of the sleeve in relation to the same part of the shaft or spindle. That is, one must allow the sleeve to have this amount of free movement on the spindle, with rolls of 1000 to 2000 mm. rolling width experiments have shown that at least 5 mm. must be allowed. This amount of freedom in addition -to the expansion of the usual sleeve members is however often much too much for practical requirements in rolling mills. According to this invention this clearance is reduced to a half or Q 1st.- ay toabout 2 to 3 mm. even for rolls of 200a mm. width and more. By these means all practical requirements are fulfilled.

This result .is obtainedas follows: Adjacent the enlargement c of the shaft or spindle. a on which the sleeve or shell bis forced there is, on

a the shaft, a second smaller concentric enlargement d of such size that it can pass through the bore of the heated sleeve for assembly. In the bore of the sleeve or shell a, a corresponding groove e is provided the'diameter of which is greater than that of the enlargement d, and its widthallows the enlargement das much play as the possible expansion of the small part of the sleeve between the inner edge of the enlargem'ent cand the adjacent edge of the smaller enlargement d. Experiments have shown that about 2 mm. sufiices even for quite longrolls of about 2000 mm. width.

This enlargement d thus allows'the sleeve to move no more than 2 mm. from its normal position and thus objectionable wandering is effectively avoided.

' It will be understood that instead of the small-1 er enlargement d on the shaft or spindle a, a

corresponding projection may 'be provided .in, the, bore of the sleeve b which co-operates with a correspondingly deep and wide groove :in the shaft, and such an arrangement is shownin Fig.

-2 in which the said corresponding projection is represented bythe reference letter d" and the said groove in the shaft -is represented? bythe reference. letter e. t

It is essential accordin the sleeve or shell b and-the shaft or spindle a should fit one another with as even as possible a shrinkage pressure except for the portion where there is play between the collar d andlthe' groove e. A portion of the bore of the sleeve or shell is supported by shrinkage on the carrying -'portion of the shaft a and another portion is sup ported by the largerdiameter enlargement c and experiments have confirmed moreover that creeping of the sleeve or shell around the shaft or spindle is avoided. I

In the embodiment according to Fig. 3 the .invention is .shown in such manner that the two enlargements which limit the movement of the sleeve or shell to left or right on, its support are spindle a is provided at the centre with the equivalent of the smaller diameter enlargement indicated by the reference letter R: whereby an annu- 2,215,424 v n shoulder n is formed against which the sleeve v other side.

i to the invention that or shell iis retained when forced into position. This enlargement k is such that the sleeve can be forced thereover when heated for the shrinkage; A groove 1 is provided in the sleeve bore'fo'r this enlargement k, which is just'as wide as the enlargement but somewhat larger in diameter. This enlargement k absolutely prevents movement of the sleeve or shell from its retaining shoulder h when the sleeve becomes heated in normal use. ,The shaft a-at one side 0 of the enlargement is is larger in diameter than at the This construction shown in Fig. 3 has the advantage moreover that, as a result of the recessing of the sleeve bore near its centre, the two halves of the bore can be finished more accurately in relation to'the axis than if the bore extended from one end to the other at the same diameter. Further it 'is possible without difllculty to form the enlargement on the spindle, for limiting the movement of the sleeve or shell to fit the corresponding part in the bore accurately.' Measuring errors, which occur when a groove 'for a shrinkage enlargement k or the 'like'is provided in a continuous bore, are hereby avoided, since the one side of this groove. corresponds exactly with the recess in the bore.

The improved method .of manufacture of com- "bined rolls according. to the invention will be apparent from the foregoing. The shaft and the sleeve or shell are worked in the knownmanner for the shrinkage fit. Then thesleev'e is heated to the shrinkage temperature and slid in known manner on to the shaft until the step c or 72. is reached. Thereby the groove e. or I in the bore engages'the. small enlargement d or k on the shaft in order to grip such enlargement on cooling, without, however, the baseof the groove e or 1 coming into contact with the peripheral face of. the shaft enlargement d or k.

A rollfor rolling metals or for the rubber, paper'and dyeing industries and similar purposes, which comprises ashaft, a sleeve shrunk thereon, andmeans for anchoring said sleeve upon said shaft, while permitting thermal expansion and contraction of said sleeve, which means comprise a circumferential enlargement on the shaft .at the extremity of the sleeve, the sleeve being shrunk on to the enlargement and shaft, and a second narrower enlargement on the shaft a short distance axially from said first enlargement 'and'of such diameter that it can pass through the bore of the sleeve when the latter is heated prior to shrinking on the shaft, 'said sleeve being grooved to receive said second enlargement, the depth and width of the' grooving being such asto maintain the contiguous faces of the enlargement and groove just sufliciently apart to allow for possible thermal expansion of the sleeve. I

- FRIEDRIGH WILHELM KLEIN.

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