CA1063394A - Split type sectional forming roll - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A split type sectional forming roll in which a split roll is formed by at least two roll segments. The separating line of a roll segment has an acute angle in a section of the segment adjacent to a side portion of another roll segment has an angle to a vertical line which is perpendicular to a roll shaft in outer peripheral portion and a separating line parallel to the above described vertical line in inner peripheral portion.
Thus the roll segments prevents damages of roll such as breakage or chipping out so that this split type sectional forming roll has a longer life sharply.

Description

3106339~
This invention relates to a split tvpe sectional forming roll which comprises a pluralit~ of roll segments formlng a desired roll profile an~ cooperating as a unit roll.
A forming roll generally has to be made of high grade materials such as high alloyed special steels to realize proper quality of formability of rolls. A roll of higher grade material can be made of smaller dimensions due to improved strength, toughness and wear resistance properties.
When an integral roll is difficult to make due to the fact that the size is too big or it is impossible to make a desired roll profile due to some other reasons, a split type roll is adopted which comprises a plurality of roll segments combining to produce a desired profile.
The conventional roll segments that have been generally adopted in split type rolls are as ~ollows: `
A split type roll in which a profile is made up by a combination of roll segments, each having a different profile, namely, one roll segment has an acute angle (hereinafter called a sharp edged roll segment) and another roll segment has an ;
obtuse angle (hereinafter called a dull edged roll segment) as viewed in cross section. Each segment forms a part of a profile line when the segments are assembled adjacent to each other.
In rolling operation, a very high stress concentration `
o~ten arises at an area near the sharp edged roll segment, . . .
exceeding the allowable stress limit, thus giving rise to a relatively ~requent damage to the sharp edged roll portion.
In addition, a sharp edged portion of the sharp edged roll segment also tended to be easily damaged during its machining or duriny tho assemblin~ work by being struck by a tool or the like. The frequency of the occurrence of such accidental damage was considerable. `
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~-; Once a roll is damaged, it is necessary to become ; repaired or replaced by a new roll, depending upon the extent of the damage. A total operation life of known roll therefore is relatively short. Furthermore a broken roll may spoil the work or damage the mill equipment. These accidents have been a serious problem in the art of roll forming and seriously reduced production efficiency. Also, the roll surface is gradually worn down due to friction between a roll surface and a plate or a strip being rolled, so that the profile gradually deforms.
To restore a worn profile to the original shape, the worn roll surface is usually reground by grinding thus unavoidably reducing the roll diameter.
Even when the extent of the roll damage is very slight and permits restoration work on the profile, a reduction of diameter by regrinding a damaged roll is usually from 5 to 10 times that encountered on restoration due to a mere wear. `
In other words, even when the damage is very slight, the total operation life of the roll will be seriously reduced to about l/S to 1/10 of the regular operation period.
If the damage is extensive, the roll li~e is shortened even more severely.
In the conventional split-type sectional forming rolls using the aforesaid sharp-edged roll segments, due to the tende~cy o~ becoming easily damaged as a consequence o~
a relatively low strength of the sharp edged part, it has been difficult to carry out working of the material with sufficient roll-down force, so that roll passing had to be done with somewhat insufficient reduction ratio.
A first object of the present invention is to provide a split type forming roll having a near square edged `` lL~6339~
roll segment having higher strength, instead of the conventional combination of sharp-abutted edged roll segments, and also satisfying a longer service life and having an improved resistance to chipping.
A second object of the present invention is to provide a split type sectional forming roll capable of heavy duty forming.
In general terms, the present invention provides a split type sectional forming roll comprising a plurality of ~: roll segments assembled together on a roll shaft to constitute a desired roll profile, including at least one curved section, at least two adjacent segments of said plurality of roll segments mating along surfaces which are convex-concave frusto- ;~
conical and intersect at said curved section, wherein inner ; planar portions of said ma~ing convex-concave frusto-conical surfaces extend perpendicularly with respect to the longitudinal axis of said roll sAa~t and wherein outer slanting portions o said convex-concave rusto-conical mating surfaces extend obliquely with respect to both the longitudinal axis of said roll shaft and a line which is both oblique with respect to said longitudinal axis and tangential with respect to the roll profile at the peripheral point of said pro11e at wh.tch ~aid ;
rusto-concial surfaces mate, said slanting por~ions extending `;
at an angle ~A included in an angle ~V formed between lines passing through said peripheral point which are normal to said tangential line and to said longitudinal axis, respectively. ;
In one embodiment, the xoll profile is a convex curved roll profile. In another embodiment, the roll profile is a concave curved roll profile. In a still further embodiment, the roll profile is a curved and straightened roll profile.
Fig. l is an elevation of a conventional split roll.
Fig. 2 is a partial cross section of Fig. l of a conventional roll and indicate forming forces working on a weak strength area of the roll segment.
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Fig. 3 is a sectional elevation of one of the embodiments of the present invention.
Fig. 4 is a detail of Fig. 3.
Fig. 5 is a partial elevation of another embodiment of the present invention.
Fig. 6 and Fig. 7 are details of Fig. 5.
Fig. 8 is a partial elevation of still another embodiment of the present invention.
Fig. 9 (on the sheet of Fig. 3) is a partial cr~ss-sectional view of yet another embodiment of the presentinvention.
Fig. l is a schematic elevation of a conventional split type sectional forming roll. Convexed roll l (upper roll) comprises roll segments 11, 12 and 13, and these are set on a roll shaft 3. Concaved roll 2 (lower roll) also comprises roll segment 21, 22 and 23, and these are set on a roll sha~t 4. Convexed roll l and concaved roll 2 are face each other and rotate so as to ~orm a strip W into a desirable shape by being passed through a roll caliber gap which is made up of the rolls 1 and 2.
As shown in Fig. l, convexed roll l is separate~ into three roll segments ll, 12 and 13 and concave roll 2 is separated into three roll segments, similarly. Each roll segment 11, 1~, 13, 21, 22 or 23 is separated by a vertical line perpendicular to the roll shafts, respectively, and has a plane side end `surface. ~ , There~ore, this type of split roll can be classified as having two different types of roll sections mounted on the same shaft and the sectional portion of said two different roll segments adjacent to each other, one is a sharp edged roll segment and the other is a dull edged roll segment.

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As shown in Fig. 2, under the pressing down of co-operating rolls, working force Fr is applied on the roll face as a reaction of the roll pressing down operation.
In Fig. 2, a lower shaft (not shown Fig. 2) is bent due to the force Fr, but as described above, a plurality o roll segments are mounted on the lower shaft to prevent a movement in an axial direction and as indicated Fig. 2 in enlarged scale, the roll segments sometimes contact each other~ in the outer periphery of the roll segment under load ~-b~ the force Fr. A gap between the end surfaces of the two adjacent roll segments becomes maximum at the side ends of the caliber profile opposite to the portion under load of the ` force Fr.
Accordingly, if a sharp edged roll segment contacts with an adjacent dull edged roll segment while being loaded, a side end outer periphery of the sharp edged roll segment is ' subjected to a concentrated load by the force Fd due to ;l bending of the lower sha~t, in addition to the force Fr.
Usually both the sharp edged roll segment and the dull edged roll segment are made of same material and same quality, so it is apparent that the sharp edge o~ the sharp edged roll segment turns out to be the weakest point o~ a~
whole roll, thus in most cases may be damaged by the combined Eorce of ~d and Fr as described above, 50 that many defects already described remain unsettled in conventional rolls.
As to the convexed roll, the same is true as in I the cas~ o~ the concaved roll a~ described above.
An embodiment of the present invention will be described with reference to Fig. 3.
In Fig. 3, line T - T' iS a tangential line at a separating point on a caliber surface of the two roll segments, and line V - V' is perpendicular to said tangential line T - T'.

' ~63394 Line N - N' is perpendicular to a roll shaftO

A convexed roll 5 comprises roll segments 51, 52 .~
and 53 and a concaved roll 6 comprises roll segments 61, 62 and 63. These are set on upper roll shaft and lower roll shaft, respectively, the same as the conventional split rolls~
. The present invention is different from the conventional i split rolls with regard to the manner of separating two adjacent roll splits. In conventional split rolls, a roll separating line between two adjacent split roll segments is straight i 10 and perpendicular to the roll shaft, that is, in the conventional ., .
split rolls, the roll separating line is parallel with line . N- ~' whereas the present invention the roll separating line ' is not straight.
~ ~t the side end portions of the sharp edged roll segment, the portion near the caliber proile sur~ace of the segment is not separated along a surace or plane parallel to i a geometric vertical or radial line or plane N - N' perpen- ;
dicular to the roll shaft, as in Fig. 1. Instead, the surface A, B, of separation includes a slanted portion A oblique to the radial line or plane N - N' at its outer periphery and is followed by an inside portion B which is generally parallel with the radial plane N - N'.
A split type sectional forming roll of the present invention thus compr~ses a plura~ity of roll segments assembled together on a shaft to consitute a desired roll caliber profile, two adjacent roll segments mating sli.dably with a slight gap at their convex-concave frusto-conical mating surfaces, being tapered near the outer peripheral portions of the segments and being generally radial relative to the axis of the roll shaft at their inside portions, a slant line representing the tapered -~portion of the trapezoidal mating surface in its cross section being convergent relative to the geometric vertical line N - N' ", , . , ~

~3633~4 perpendicular to the roll shaft (i.e. radial) and being coincident with the separating point at the caliber surface of the two adjacent segments and being disposed with respect to said radial line at that portion of the geometric normal line V - V' which is located within the roll segment, said geometric normal li~e V - V' being perpendicular to the tangential line T - T ' at the separating point.
A fundamental feature of the present invention is in providing a frusto-concial parting surface to avoid a sharp profile line between two adjacent roll segments, as opposed to a flat or generally planar parting surface of the roll segments of the conventional type split roll.
The above men~ioned frusto-conical parting surface is formed by a tapered cylindrical surface A and a flat surface B perpendicular to the axis of the roll.
The extent of the advantages brought about by this feature varies greatly depending upon many factors such as operating conditions, grade of the material to be used, design factors defined by the balance between the dimension of the relevant component parts, as will be explained hereafter by referring to the accompanying Fig. 4. Fig. 4 is an enlarged detail of Fig. 3 showing a Part thereof adjacent to the portion where line T - T', line V - V', line N - ~' and the slant line intersect . .' The following equation represents the relation between an angle 4V of intersection of lines N - N' and V - V', and an angle 4~ of intersect~on of lines N - N' and slant line A:
4A a4V + ~ 4V = (1 ~ G~)~V
=K4V

Quality ranking o the split roll of this invention in terms of constant K is as follows:

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0.4 - 1.6 Better .~ , ~ - _ .~: ' O.7 - 1.3 ~ur-ther better .;, .... _.................. , __ , _ 8 0 9 - 1.................. Best ,.,' ~ ~ .
~ig. S is another embodiment of the present inventlon.
A convex roll 50 comprises two roll segments 501 and one roll segment 502 between the two. Similarly, a concave roll 60 comprises two roll segments 601 and a roll segment 602 therebetween. This arrangement is very similar to that of Fig. 3. The dif~erence is in that the roll segments 501 and 502, which constitute a part of the convex roll 50, are i separated by a narrow gap within a value permissible for roll forming so that the two segments do not directly contact each other. The roll segments 601 and 602 of the mating concave :' roll 60 are also separated from each other by a gap in a same ~ manner as in the case of roll segments 501 and 502. Roll ,l segments of idle rolls 501 and 601 are freely rotatable on the roll shaft assembly including suitable bearings etc., as shown !`
in Fig. 5. Thus, the combination of rolls 50 and 60 comprises a pair of driven roll segments 502, 602 and two pairs o~ idling !~ roll segments. ;~
In Fig. 5 an idling section roll comprises a flange roll segment 601, a sleeve 31, a dual thrust roller bearing 32, needle roller bearing 33, side cover 34 and 35, an oil seal 36, a labyrinth packing 37, a supporting plate 38 and a stopper ring 39, rotatably supported by the dual thrust taper roller bearing 32 and the needle roller bearing 33. The sleeve 31 is secured to the driving shaft by means of a key. The needle roller bearing 33 is disposed on the sleeve 31 at the smaller diameter axial end or side of the flange roll segment 601 and . ~ ~

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in order to prevent axial displacement, the inner race 40 ; thereof is held in abutting engagement with the side cover 34 and the outer race 41 thereof is set in position by the stopper ring 39. The oil seal 36 is provided on the smaller diameter side of the flange roll segment 601 for sliding movement on the side cover 34. The dual thrust taper roller bearing 32 is mounted on the sleeve 31 at the larger diameter axial end or side of the flange roll segment 601 and held against axial dis-placement by the side cover 35. The labyrinth packing 37 is supported by the dual thrust taper roller bearing 32 and the supporting plate 38 and is relatively slida~le around the side cover 35. An oil passage 42 is defined by the flange roll segment 601 and the sleeve 31 between the dual thrust taper roller bearing 32 and the needle roller bearing 33, for the passage of lubricant oil therethrough. Reference numeral 43 designates a lubricating oil passage for feeding the lubricating oil ~rom an oil cup 44.
Fig. 6 is a detailed view of a slant line A50 of Fig. 5. In this case the slant line A50 is perpendicular to the tangential line T - Tl at a separating point on the caliber surface of roll 50 and is coincident with line V - V'. Therefore, an angle eA formed by a line N - N' normal to the axis of the convex roll 50 and slant line A50 is equal to an angle 4V in formula ~A ~ K4V ~orm~rly described. Cons~quen~ly, in this case, K equals 1 and is ranked "best", and can be said to be the best mode of the embodiment of this invention.
Fig. 7 is a cletailed view of slant line A60 of Fig. 5. In this case, K is also 1 for the same reason as above described and is also ranked "best".
The above embodiment is believed to produce maximum advantage of the present invention. In Fig. 5, roll segment 501, forming convex roll S0, is assembled in the same manner as the g :.
aforesaid segment 601. Therefore, the bearing assembly of segment 501 is not shown. In the embodiment of Fig. 5, there is a clearance between roll segments but the clearance has to be set within a very small value to avoid damages to the bearings during the rolling operation due to an uneven load or shock caused by undesired shaft deflection shown in Fig. 2. Even in normal operation, which is not accompanied by the stress conditions as above, it is still desirable to reduce the residual prestress of the roll segment by means of an appropriate heat treatment and care should be taken to avoid any sharp edges or corners, thereby reducing the coefficient of working stress concentration as much as possible, which, in turn, improves the total toughness of the arrangement.
Those skilled in the art will appreciate that the length of the slanted portion has to be of balanced dimensions , by considering contributing factors such as the slant angle,; diameter, width, pro~ile of the roll segment and the properties of material to be used.
Fig. 8 is a still further embodiment of the present invention. As in Fig. 5, the sharp edged roll segment the separating line o~ outer periphery of axial ends of ad~acent roll segments is at an angle to the vertical line N - N' in the outer perip~eral portion and is parallel to the vertical line N - Nl in inner peripheral portion. Furthermore an idling section comprises roll segments 501 and 601 as an idling partial section roll. A ~lange roll segment 601 is rotatably supported by a paix of axially spaced roller thrust bearings 45 and 46 interposed between the flange roll 601 and sleeve 31 fixed to a drive shaft by a key. Thrust roller bearings 45 and ~6 are arranged at respective axial end and are each provided with a set of lubricant seal means 36.

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A yet another embodiment of the present invention is shown in Figure 9, wherein the profile of the rolling surface is a combination of a straight surface of the segment corresponding to segment 62 of Figure 3, while the surface of the segment corresponding to segment 61 of Figure 3 is curved.
n this embodiment, the slanted portion A is disposed such that the angle 4A equals about 0 7 ~v (cf. Fig. 4 and Fig. 5 and refer to the above table of R values).
As mentioned above, none of the roll segments of the , . . . 10 split roll of this invention have any sharp edged corners near the caliber surface and thus aims to equalize the strength which is greatly effected by the shape of the roll segments, thus there exist no weak point with respect to the strength o~ the rolls. In other words, the rol-l segments of the split roll of this invention have improved resistance to breakage ;~
and also has other superior advantages as mentioned hereafter.
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', Some embodiments of the present invention have been explained which consist o~ three roll segments, which constitute a roll caliber of a desired configuration and size when they are assembled together on a roll shaft.
, But,these embodiments are not to be interpreted as ¦ limiting the scope o~ the present invention.
~he explanation of the present invention has been mainly referred to the lower split roll, but it goes without saying that the concept of the present invention can also be applied in the upper split roll and will achieve the same advantage.
The same applies in the case where roll segments o~ a split roll are all driven.
Advantageous effects of the present invention are as follows: ~

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36;~394 1. No roll segments constituting a split roll have any sharp edges or corners, so that roll damage encountered in the conventional split roll such as breakage or chipping out will not arise.

2. Total roll li~e of the split rolls according to the present invention is greatly prolonged over that of conventional split rolls, and repair costs of a damaged ' roll or adjustment cost for a substitute roll are reduced as the following problems are no longer encountered in the split - 10 roll of this invention:
(A) Even when damage occurring in the conventional split roll is relatively slight and repairable, repairs are carried out by machining work such as cutting, grinding and the like to remove the damaged caliber portion o outer peripher~
of the split roll and to restore a desired caliber proile, this work naturally results in an inevitable reduction of the outer diameter of the split roll as compared with that o be~ore repair.
The extent of this reduction in the outer diameter of the split roll is usually larger than, say, several-ten-fold o that of the roll which is not damaged but is merely worn due to a long period of use.
~B) Whichever roll se~ment o a spli~ roll i9 damaged, all the roll segments assem~led on the same roll shaft must undergo repair in order to provide uniormly reduced outer diameter a the roll sections including the roll segments which were not damaged. Thus, the reduction in repair o any segment reduces the need for reaching the good segments that have not been damaged or worn.
(C) If the extent of the damage is serious and it is not possible to make a repair, a new substitute split roll must be replaced therefor even though the remaining segments are in operable condition.

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3. Production efficiency is greatly increased bv using the split roll of the present invention ovex the conventional split rolls. This is due to the ~act that it is possible to cut down dead time caused by roll damage during the running.
The number ofi re,ects such as scratched tubes or deformed tubing :.. ,. - :
caused by the damaged split rolls is also reduced.

4. The need to prepare or store spare roll segments against possible roll damage is greatly reduced.

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Claims (16)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A split type sectional forming roll comprising a plurality of roll segments assembled together on a roll shaft to constitute a desired roll profile, including at least one curved section, at least two adjacent segments of said plurality of roll segments mating along surfaces which are convex-concave frusto-conical and intersect at said curved section, wherein inner planar portions of said mating convex-concave frusto-conical surfaces extend perpendicularly with respect to the longitudinal axis of said roll shaft and wherein outer slanting portions of said convex-concave frusto-conical mating surfaces extend obliquely with respect to both the longitudinal axis of said roll shaft and a line which is both oblique with respect to said longitudinal axis and tangential with respect to the roll profile at the peripheral point of said profile at which said frusto-conical surfaces mate, said slanting portions extending at an angle ?A included in an angle ?V formed between lines passing through said peripheral point which are normal to said tangential line and to said longitudinal axis, respectively.

2. The split type sectional forming roll as claimed in Claim 1, wherein said roll profile is a convex curved roll profile.

3. The split type sectional forming roll as claimed in Claim 1, wherein the roll profile is a concave curved roll profile.

4. The split roll as claimed in Claim 1, wherein the roll profile is a curved and straightened roll profile.

5. The split type sectional forming roll as claimed in Claim 1, wherein an angle ?A formed by said vertical line and a slant line oblique to said vertical line and an angle ?V formed by said normal line and said vertical line are expressed by a formula ?A = K?V, wherein K is a constant and the value of the constant K exists between 0.4 and 1.6.

6. The split type sectional forming roll as claimed in Claim 5, wherein the value of the constant K exists between 0.7 and l.3

7. The split type sectional forming roll as claimed in Claim 5, wherein the value of constant K exists between 0.7 and 1.1.

8. The split type sectional forming roll as claimed in Claim 7, wherein one or more of the said roll segments is (are) driven and the remaining of the roll segments to be made idle separately.

9. The split type sectional forming roll as claimed in Claim 8 which further comprises a sleeve fixedly mounted on a driving shaft; two sets of bearings provided between said sleeve and said roll segment, one of said two sets of bearings is a needle roller bearing provided on a smaller diameter side of said roll segment and the other set of bearing provided on a larger diameter side of said roll segment being thrust roller bearings; an oil passage being arranged to communicate between said needle roller bearing and said thrust roller bearing being capable of supplying lubricating oil from any oil supply means and a set of oil seals exteriorly provided to each of said needle roller bearing and said thrust roller bearing respectively.

10.The split type sectional forming roll as claimed in Claim 8, which further comprises a sleeve fixedly mounted on a driving shaft; a set of thrust roller bearings being arranged to space to the direction of the roll shaft between said sleeve and the roll segment; and a set of oil seals exteriorly provided to each of said thrust roller bearing.

11. The split type sectional forming roll as claimed in Claim 7, wherein said roll segments are assembled together on a non-driven roll shaft.

12. The split type sectional forming roll as claimed in Claim 1, wherein said roll segments are assembled together on a non-driven roll shaft.

13. A split type sectional forming roll according to Claim 12, wherein said convex-concave frusto-conical surfaces slidably mate with a slight gap therebetween.

14. The split type sectional forming roll as claimed in Claim 1, wherein one or more of the said roll segments is (are) driven by a roll shaft and the remaining of the roll segments to be made idle separately.

15. A split type sectional forming roll according to Claim 14, wherein said convex-concave frusto-conical surfaces slidably mate with a slight gap therebetween.

16. A split type sectional forming roll as claimed in Claim 15, wherein one or more of the said roll segments is driven by a roll shaft and the remaining of the roll segments to be made idle separately.