WO2000051771A1

WO2000051771A1 - A method and apparatus for slitting strip

Info

Publication number: WO2000051771A1
Application number: PCT/AU2000/000144
Authority: WO
Inventors: Steven Bruce Gale
Original assignee: Bhp Steel (Ais) Pty. Ltd.
Priority date: 1999-03-01
Filing date: 2000-02-29
Publication date: 2000-09-08
Also published as: AUPP895899A0

Abstract

There is disclosed a method of preparing an arbor (10a) of a slitting machine for slitting strip in a direction along the strip. The method comprises using ring shaped shim (38) on the arbor to alter a clearance (40) between the outer work face of a stripper ring (16) encircling the arbor and a slitting edge (20) of a knife (12) of the arbor. The stripper ring has an internal diameter dimensioned for allowing substantially free rotation of the stripper ring about the arbor in the absence of the shim. By either using the shim or removing it from the arbor, the same stripper ring can be used in the slitting of different strip differing in thickness from one to the next. There is also disclosed a slitting machine incorporating an arbor carrying shim encircled by a stripper ring as described above.

Description

A METHOD AND APPARATUS FOR SLITTING STRIP

Field Of The Invention

The present invention pertains to the longitudinal slitting of strip. The invention

finds particular application in the processing of metal strip as it is unwound from a coil

of the strip.

Background Of The Invention

Slitting machines of the type having counter rotatable substantially parallel top and

bottom arbors with co-operating knives for slitting metal strip in a longitudinal direction

as it is passed between the arbors are known in the art.

Generally, each arbor carries at least two knives spaced apart from each other

along the arbor by spacer rings to provide a requisite spacing therebetween. The knives

and spacer rings are keyed onto the arbor to prevent rotation of them relative to the

arbor. A set of resilient stripper rings for pressing against the metal strip while being slit

and arranged side by side relative to one another encircle the spacer rings. The stripper

rings are axially slid over the spacer rings when being positioned on the arbor and are

maintained in position relative to the arbor by virtue of a friction fit over the spacer

rings.

The stripper rings each exert a reaction force on the strip by virtue of their

resilience, which acts to maintain the strip in a substantially straight path of travel as it

issues from between the arbors.

Problems occur if the stripper rings are of incorrect thickness in relation to the

thickness of the metal strip being slit and the size of the knives used. One such problem is that the strip can abrade the knives thereby leading to excessive knife wear and to

shortening of the working life of the knives. The strip itself can also be marked by non-

slitting edges of the knives. Another problem is that strip, and in particular thick strip,

tends to require manual intervention in order to be returned to the desired path of travel

upon issuing from between the arbors. This is particularly undesirable from a safety

viewpoint as it means personnel are required to work in the vicinity of the rotating

arbors. Moreover replacement of the knives is expensive and losses can be incurred as a

result of damage to the metal strip during the slitting operation.

When the knives of an arbor wear they are generally reconditioned by grinding

down the slitting edge of each to a reduced diameter and presently, it is common practice

to also grind down the work faces of the set of stripper rings with each reconditioning of

the knives so that a suitable clearance between the slitting edges and the work faces of

the stripper rings is maintained. As such, when the set of knives reach the end of their

working life the set of stripper rings is also discarded.

In addition, at present different sets of stripper rings are used for the slitting of

metal strips having a different thickness relative to one another in order that the required

clearance between the work faces of the stripper rings and the slitting edge of each knife

on the arbor on which the stripper rings are carried is provided. The need to maintain a

potentially significant number of different sets of stripper rings is expensive.

Examples of prior art slitting machines are disclosed in EP 444008A, JP 10225818

and RU 2086364. More particularly, in European patent application EP 444008A there

is disclosed a slitting machine incorporating opposed counter rotatable arbors carrying

knives for slitting lengths of paper, textiles, aluminium foils and the such like. Each of the arbors carries loose stripper rings arranged in offset positions relative to one another

along the arbors for assisting separation of cut strips of the relevant material being slit.

The machine disclosed in Japanese Patent 10225818 also incorporates opposed counter

rotatable arbors carrying co-operating knives for slitting thin sheet material. Each of the

arbors are respectively encircled by loose stripper rings having an axis of rotation offset

relative to the corresponding arbor around which they encircle. The rings are arranged to

press against thrust rolls and be spaced from the arbor during the slitting of the strip.

A similar arrangement is disclosed in Russian Patent RU 2086364. In this instance

loose stripper rings are again spaced from the corresponding arbors they respectively

encircle during the slitting of thin sheet material, and bear against thrust rolls in the use

of the machine. The axis of rotation of each stripper ring is offset with respect to the

axes of rotation of the arbors, and their position relative to those of the arbors is able to

be adjusted by adjustment of the position a support frame on which the thrust rolls are

carried.

Summary Of The Invention

It is an aim of the invention to address one or more problems of the prior art or to

at least provide an alternative to the prior art.

Broadly stated, the invention relates to the utilisation of at least one stripper ring of

a predetermined size on an arbor of a slitting machine in the sequential slitting of strip as

it is fed from different coils wherein the thickness of the strip differs from coil to coil,

and is directed to the positioning of shim under the stripper ring to thereby alter the

clearance between the work face of the stripper ring and the slitting edge of a knife of the

arbor. In a first aspect of the present invention there is provided a method of preparing an

arbor of a slitting machine for slitting strip in a direction along of the strip, comprising

the steps of:

(i) selecting ring shaped shim to suit the thickness of the strip to be slit;

(ii) locating the shim on the arbor such that the shim is received around the

arbor; and

(iii) positioning on the arbor at least one stripper ring for contact with a face of

the strip while being slit, such that the stripper ring is received around the arbor

and encircles the shim;

wherein the stripper ring has a substantially uniform wall thickness and an internal

diameter dimensioned for allowing substantially free rotation of the stripper ring about

the arbor in the absence of the shim.

The method may also comprise sliding at least one spacer ring onto the arbor such

that the spacer ring is received around the arbor, wherein the spacer ring is for spacing

along the arbor a knife or knives for achieving the slitting of the strip, and the shim

encircles the or at least some of the spacer rings when the shim is located on the arbor.

Typically, the shim will comprise a number of separate shim rings having

substantially the same wall thickness as each other, and the locating of the shim will

comprise arranging the shim rings side by side relative to one another along the arbor.

Preferably, a number of stripper rings having substantially the same wall thickness

as each other will be positioned side by side relative to one another along the arbor.

In a second aspect of the present invention there is provided an arbor of a slitting

machine when prepared by a method as described herein. Different strip that differ in thickness from one to the next can be sequentially slit

with use of a stripper ring of a predetermined size, by selecting a shim having the

requisite wall thickness needed for the desired clearance between the work face of the

stripper ring and the slitting edge of a knife of the arbor to suit each respective strip, or

by omitting the use of shim in the slitting of a strip of one thickness and utilising shim in

the slitting of another strip having a different thickness.

Accordingly, in a third aspect of the present invention there is provided use of at

least one shim ring on an arbor of a slitting machine for slitting strip in a direction along

the strip, to alter a clearance between a slitting edge of a knife of the arbor and a work

face of a stripper ring for contact with a face of the strip while being slit, wherein the

stripper ring is received around the arbor and has an inner diameter dimensioned for

allowing substantially free rotation of the stripper ring about the arbor in the absence of

the use of the shim ring.

In a fourth aspect of the present invention there is provided a method of slitting

different strip that differ in thickness from one to the next utilising a slitting machine

incorporating a pair of opposed counter rotatable arbors provided with co-operating

knives for slitting each of the strip in a direction along said strip as the strip is passed

between the arbors one at a time, and at least one stripper ring of the predetermined size

that has an outer work face for contact with the strip while being slit and which is carried

on one of the arbors, wherein the method comprises:

(i) causing the one said strip to be slit by the knives of the arbors as the arbors are

rotated counter to one another, while ring shaped shim is received around the one said arbor on which the stripper ring is carried and arranged between the stripper ring and that

said arbor such that the shim is encircled by the stripper ring; and

(ii) causing the next said strip to be slit by the knives of the arbors as the arbors are

rotated counter to one another while other ring shaped shim is received around the one

said arbor between the stripper ring and that said arbor such that the other shim is

encircled by the stripper ring, or without any shim arranged between the stripper ring and

the one said arbor;

wherein the shim used in step (i) has a thickness different to the shim used in step

(ii), and the stripper ring has a substantially uniform wall thickness and is dimensioned

for being substantially freely rotatable about the one said arbor without any shim

arranged between the stripper ring and the one said arbor.

The method may be used to slit strip having a thickness up to about 12 mm or

greater and is particularly suitable for slitting strip having a thickness in a range of from

about 2 mm to about 12 mm.

In a fifth aspect of the present invention there is provided a slitting machine

knives for slitting strip in a direction along the strip as the strip is passed between the

arbors, wherein each of the arbors carries at least one stripper ring respectively for

pressing against the strip while being slit by the knives as the arbors are rotated counter

to one another, and wherein the stripper ring on one of the arbors is in an opposed

relationship with the stripper ring on the other said arbor and has a substantially uniform

wall thickness and an internal diameter dimensioned for allowing ring shaped shim to be

received thereunder around the one said arbor for altering a clearance between that stripper ring and a slitting edge of a said knife carried by the one said arbor, and for

allowing substantially free rotation of that stripper ring in the absence of the shim.

In a sixth aspect of the present invention there is provided a slitting machine

arbors, wherein at least one of the arbors carries at least one stripper ring received around

the arbor for contact with the strip while being slit by the knives as the arbors are rotated

counter to one another, and which is positioned over shim encircling the arbor, wherein

the stripper ring has a substantially uniform wall thickness and an internal diameter

dimensioned for allowing substantially free rotation of the stripper ring about the arbor

in the absence of the shim.

The or each stripper ring carried by the one arbor may also be freely rotatable

about the shim.

The term "strip" will be taken to include sheet and plate material. The strip will

usually be a metal strip and most usually, steel strip. The shim may be formed from any

stiff material deemed suitable. Preferably, the shim will be made of a metal such as

brass or stainless steel, a polymeric material such as a polyurethane or for instance,

fibreglass. The shim will typically be in the form of a closed ring.

By being able to use the same stripper ring or stripper ring set in the slitting of a

range of different strips differing in thickness from one to the next, a significant

reduction in the number of different sizes of stripper rings previously needed to enable

the range of strips to be slit can be achieved resulting in substantial cost savings. The

use of shim also ensures that the clearance between the slitting edges of the knives and the work face of each stripper ring is maintained substantially as required for the strip to

issue from between the arbors in a generally straight path of travel. This minimises the

potential for wearing of the knives and damage to the strip.

Accordingly, not only may safety aspects of the use of slitting machines be

improved by reducing or avoiding the need for personnel to manually correct the path of

travel of slit strip, but significant cost savings may also be had as a result of lengthening

the working life of the slitting knives while at the same time, loss of product resulting

from damage to the strip during the slitting operation can be minimised. Furthermore,

the need to grind down the work face of a stripper ring or stripper ring set with each

reconditioning of the knives of an arbor can be avoided leading to longer stripper ring

working life and so further significant cost savings.

The advantages and features of the invention will now be further described

hereinafter with reference to a number of preferred forms illustrated in the accompanying

drawings.

Brief Description Of The Accompanying Drawings

Figure 1 is a diagram illustrating stripper rings arranged on an arbor of a stripping

machine of the prior art;

Figure 2 is a diagram illustrating the stripper ring arrangement of top and bottom

arbors of a slitting machine of the prior art;

Figure 3 illustrates the slitting of sheet material using an arbor arrangement as

shown in Fig. 2;

Figures 4a and 4b illustrate the compression of stripper rings in the prior art when

not suitable for the thickness of the sheet material being slit; Figure 5 illustrates stripper rings positioned on an arbor in accordance with an

aspect of the present invention in comparison to a stripper ring arranged on the arbor in

the manner of the prior art;

Figure 6 illustrates the placement of shim under stripper rings positioned on an

arbor in accordance with the present invention;

Figure 7 is a cross-sectional view taken through VII-VII of Fig. 6;

Figure 8 is a cross-sectional view taken through VIII-VIII- of Fig. 6; and

Figure 9 is a cross-sectional view taken through IX-IX of Fig. 6.

Detailed Description Of Preferred Embodiments Of the Invention

The arbor 10 prepared in the manner of the prior art is indicated in Fig. 1. The

arbor carries a pair of knives 12 spaced apart from each other along the length of the

arbor by a plurality of spacer rings 14. The spacer rings 14 and knives 12 each have a

keyway defined in their respective inner peripheries which receive a key seated in a

keyway of the arbor extending longitudinally therealong, and which prevents the spacer

rings and knives from rotating in a circumferential direction about the arbor. Positioning

of the spacer rings and knives on the arbor simply involves sliding them along the arbor

one at a time.

A plurality of resilient stripper rings 16 made of polyurethane encircle the spacer

rings and are arranged side by side relative to one another along the arbor. Stripper rings

may also be made from other suitable synthetic or natural polymeric materials including

plastics and rubber, or from metallic materials including brass and stainless steel.

The stripper rings are held in place relative to the arbor by friction contact with the

underlying spacer rings. The spacer rings 14 and stripper rings 16 are maintained on the arbor by lock rings threadably received on opposite end regions of the arbor.

Accordingly, the knives 12 are also held in fixed longitudinal positions relative to one

another but can be spaced further apart or moved closer together by simply removing or

adding spacer rings as required. As will be understood, one or more stripper rings may

also need to be removed with any spacer rings.

To achieve the slitting of metal strip a pair of arbors are arranged in a face to face

relationship in a slitting machine as indicated in Fig. 2. As can be see, the bottom arbor

10a carries a set of female stripper rings 16a having a wall thickness such that the outer

work faces 18a of the stripper rings are located below the slitting edge 20 of each knife

12 carried by the bottom arbor. In contrast, male stripper rings 16b are carried on the top

arbor and have a wall thickness such that the work faces of those stripper rings are

located beyond the knives 12. A space 22 for receiving the metal strip to be slit is

defined between the arbors.

The slitting of metal strip 24 as it is unwound from a coil of same is indicted in

Fig. 3. Although not shown, strands are slit from opposite side regions 26 to 28 of the

strip by co-operating knife pairs of the top and bottom arbors as the arbors are driven

counter to one another. The reception of the strip 24 between the male and female

stripper rings 16a and 16b causes both sets of stripper rings to be compressed and exert a

reaction force on faces 30 and 32 of the strip as a result of their resilient nature. The

reaction force exerted by the female stripper rings of the bottom arbor acts to inhibit the

strip from following the direction of rotation of that arbor and so maintains the strip in a

substantially straight path of travel. The male stripper rings on the top arbor also act to

force the strip away from the outer peripheral surface 34 and inner non-slitting edges 36 of the knives 12 carried on the top arbor to thereby inhibit wearing of those knives and in

addition, lessen the possibility of marking of the strip occurring.

The hardness of the stripper rings is dependent on the sheet material to be slit.

Hard stripper rings can mark metal strip having a painted or other protective coating.

Accordingly, more compressible stripper rings are used for delicate coated metal strip

while harder stripper rings are used on metal strip able to be subjected to more robust

treatment.

If the wall thickness of the stripper rings is too great for the metal strip being slit,

the stripper rings themselves may be permanently damaged by excessive compression

causing distortion of the stripper ring cross-sectional shape as indicated in Fig. 4a. If the

wall thickness of the stripper rings is insufficient as indicated in Fig. 4b, the slit material

may not emerge from between the stripper rings in a straight path of travel, and

increased wearing of the inner peripheral walls of the knives can occur.

The stripper rings are arranged loosely between the knives to allow for their

compression when pressed against the strip. If packed tightly, it is possible for the

knives to be bent or fractured as a result of the compression of the stripper rings.

In leading to the instant invention, the present inventors have recognised that the

outer diameter of the stripper rings 16 is not essential in achieving the desired clearance

between the work faces of the stripper rings of an arbor and the slitting edge 20 of each

knife 12 carried on the arbor but rather, it is the wall thickness of the stripper rings that is

important. In this regard, if several stripper rings each have different outside diameters

but the same wall thicknesses, their work faces 18 are nevertheless spaced the same

distance over the underlying spacer rings 14 as indicated in Fig. 5 for explanatory purposes. As can be see, the two stripper rings to the left of the figure are freely

rotatable about the arbor in comparison to the stripper ring on the right side of the figure

which is restrained from rotation about the arbor by virtue of friction contact with the

underlying spacer rings in the manner of the prior art.

As the stripper rings are compressed with contact with a metal strip 24 in use, the

two stripper rings on the left of Fig. 5 would be forced against the underlying spacer

rings and caused to rotate with rotation of the arbor 10. Accordingly, even though the

outer diameter of the stripper rings shown in Fig. 5 varies from stripper ring to stripper

ring, each can still be used in the slitting of metal strip of a given thickness.

Turning now to Fig. 6, polyurethane shim rings 38 having a different wall

thickness relative to one another are shown located between stripper rings 16 and spacer

rings 14 carried on an arbor 10. While the stripper rings each have the same wall

thickness, the presence of the shim alters the position of the work faces of the relevant

stripper rings with respect to the slitting edges 20 of the knives 12. Hence, the use of the

shim effectively alters the wall thickness of the overlying stripper rings allowing the

same stripper ring to be used in the slitting of metal strip of different thicknesses or with

knife sets having different diameter slitting edges.

That is, the same stripper ring can be used in the slitting of thin strip when used in

association with shim, and for thicker strip in the absence of the shim. The stripper ring

can also be used in the slitting of strip of an intermediate thickness by utilising a shim

with a lesser wall thickness. An example of the use of shim as contemplated by the

invention is shown in Figs. 7 to 9, respectively. The relative position of the slitting edge

20 of a knife of a top arbor is indicated in those figures for clarity. In the arrangement shown in Fig. 7, the stripper ring 16 on the bottom arbor 10a

has a wall thickness of 30 mm and an internal diameter of 412 mm. The outside

diameter of the spacer ring 14 encircled by the stripper ring is 400 mm and as such the

stripper ring is quite loose and freely rotatable on the spacer ring. A gap 40 of 5 mm is

defined between the work face 18 of the stripper ring 16 and the outer circumference of

the slitting edge 20 of the knife 12 of the bottom arbor.

When shim 38 having an inner diameter of 401.5 mm and a wall thickness of 2.5

mm is arranged between the female stripper ring 16 and spacer ring 14 carried on the

bottom arbor, gap 40 is reduced to 2.5 mm as indicated in Fig. 8. When the shim is

replaced with a different shim having the same inner diameter but with a wall thickness

of 5 mm the gap 40 is reduced to zero as indicated in Fig. 9. At the same time, the gap

42 resulting from the stripper ring hanging loosely around the shim is reduced but still

remains and facilitates the sliding of the stripper ring over the shim when preparing the

arbor or removal of the stripper ring from around the shim. By having an inner diameter

slightly greater than the out diameter of the spacer rings, the shim is also able to be

readily slipped on and removed from the arbor.

Although the present invention has been described hereinbefore with reference to

preferred embodiments, the skilled addressee will appreciate that numerous variations

and modifications are possible without departing from the scope of the invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS :-

1. A method of preparing an arbor of a slitting machine for slitting strip in a

direction along the strip, comprising the steps of:

(i) selecting ring shaped shim to suit the thickness of the strip to be slit;

(ii) locating the shim on the arbor such that the shim is received around the

arbor; and

and encircles the shim;

wherein the stripper ring has a substantially uniform wall thickness and

an internal diameter dimensioned for allowing substantially free rotation of the

stripper ring about the arbor in the absence of the shim.

2. A method according to claim 1 wherein the stripper ring is substantially freely

rotatable about the shim, when the stripper ring is positioned on the arbor.

3. A method according to claim 1 or 2 further comprising:

sliding at least one spacer ring onto the arbor such that the spacer ring is

received around the arbor;

wherein the spacer ring is for spacing along the arbor a said knife for

achieving the slitting of the strip, and the shim encircles the or at least some of

the spacer rings when the shim is located on the arbor.

4. A method according to claim 3 wherein a plurality of said spacer rings are slid

onto the arbor and arranged side by side relative to another along the arbor, and

the spacer rings each have substantially the same wall thickness as each other.

5. A method according to claim 3 or 4 wherein the spacer rings are for spacing a

pair of said knives a part from one another along the arbor.

6. A method according to any one of claims 1 to 5 wherein the shim comprises a

number of separate shim rings having substantially the same wall thickness as

each other, and the locating of the shim comprises arranging the shim rings side

by side relative to one another along the arbor.

7. A method according to any one of claims 1 to 6 wherein the positioning

comprises positioning a number of said stripper rings side by side relative to one

another along the arbor, and the stripper rings have substantially the same wall

thickness as each other.

8. A method according to any one of claims 1 to 7 wherein the strip is metal strip.

9. Use of at least one shim ring on an arbor of a slitting machine for slitting strip in

a direction along the strip, to alter a clearance between a slitting edge of a knife

of the arbor and a work face of a stripper ring for contact with a face of the strip,

wherein the stripper ring is received around the arbor and has an inner diameter

dimensioned for allowing substantially free rotation of the stripper ring about the

arbor in the absence of the use of the shim ring.

10. Use according to claim 9 wherein the inner diameter of the stripper ring is

shim.

11. Use according to claim 9 or 10 wherein a number of separate shim rings having

substantially the same thickness as each other and for being arranged side by side

relative to one another are used to alter the clearance.

12. Use according to any one of claims 9 to 11 wherein the strip is metal strip.

13. A method of slitting different strip that differ in thickness from one to the next

utilising a slitting machine incorporating a pair of opposed counter rotatable

arbors provided with co-operating knives for slitting each of the strip in a

direction along said strip as the strip is passed between the arbors one at a time,

and at least one stripper ring of the predetermined size that has an outer work face

for contact with the strip while being slit and which is carried on one of the

arbors, wherein the method comprises:

(i) causing the one said strip to be slit by the knives of the arbors as the

arbors are rotated counter to one another, while ring shaped shim is received

around the one said arbor on which the stripper ring is carried and arranged

between the stripper ring and that said arbor such that the shim is encircled by the

stripper ring; and

(ii) causing the next said strip to be slit by the knives of the arbors as the

arbors are rotated counter to one another while other ring shaped shim is received

around the one said arbor between the stripper ring and that said arbor such that

the other shim is encircled by the stripper ring, or without any shim arranged

between the stripper ring and the one said arbor;

wherein the shim used in step (i) has a thickness different to the shim

used in step (ii), and the stripper ring has a substantially uniform wall thickness

and is dimensioned for being substantially freely rotatable about the one said

arbor without any shim arranged between the stripper ring and the one said arbor.

14. A method according to claim 13 wherein a clearance between the outer work face

of the stripper ring and a slitting edge of a said knife carried on the one said arbor

that is determined by the thickness of the shim used in step (i) is altered when the

other said shim is used or in the absence of any shim being arranged between the

stripper ring and the one said arbor in step (ii).

15. A method according to claim 13 or 14 further comprising:

removing the shim used in step (i) from the one said arbor subsequent to

the one said strip being slit; and

locating the other shim on the one said arbor prior to the next said strip

being slit.

16. A method according to claim 15 further comprising removing the stripper ring

from the one said arbor subsequent to the one said strip being slit and prior to the

other shim being slipped onto the one said arbor.

17. A method according to claim 16 further comprising sliding the stripper ring over

the other shim to thereby position the stripper ring over the other shim, prior to

the next said strip begin slit.

18. A method according to any one of claims 13 to 17 wherein the shim used in step

(i) comprises a number of separate shim rings having substantially the same wall

thickness as each other, and the method comprises arranging the shim rings side

by side relative to one another along the one said arbor prior to the one said strip

being slit.

19. A method according to any one of claims 13 to 18 wherein the other shim

comprise a number of separate shim rings having substantially the same wall thickness as each other, and the method comprises arranging the shim rings of the

other shim side by side relative to one another along the one said arbor prior to

the next said strip being slit.

20. A method according to any one of claims 13 to 19 wherein a number of said

stripper rings are used in the slitting of either one or both of the one said strip and

the next said strip, wherein the stripper rings have substantially the same wall

thickness as each other and the method comprises arranging the stripper rings

side by side relative to one another along the one said arbor.

21. A method according to any one of claims 13 to 20 further comprising:

feeding the one said strip to the pair of arbors from a coil of the one said

strip; and

feeding the next said strip to the pair of arbors from a coil of the next said

strip.

22. A method according to any one of claims 13 to 21 further comprising:

progressively coiling the one said strip as that strip emerges from between

the pair of arbors; and

progressively coiling the next said strip as that strip emerges from

between the pair of arbors.

23. A method according to any one of claims 13 to 22 wherein the one said arbor

carries one or more spacer rings for spacing a said knife provided on that arbor

along the one said arbor, and the shim used in step (i) and the other shim of step

(ii) encircle the or at least some of the spacer rings, when received around the one

said arbor.

24. A method according to any one of claims 13 to 23 wherein the one said strip and

the next said strip are metal strips.

25. A method according to any one of claims 13 to 24 wherein the one said strip and

the next said strip are steel strips.

26. A method according to any one of claims 13 to 25 wherein the one said strip and

the next said strip each have a thickness greater than 2 mm.

27. An arbor of a slitting machine wherein the arbor has been prepared by a method

as defined in any one of claims 1 to 8.

28. A slitting machine incorporating a pair of opposed counter rotatable arbors

provided with co-operating knives for slitting strip in a direction along the strip

as the strip is passed between the arbors, wherein at least one of the arbors carries

at least one stripper ring received around the arbor for contact with the strip while

being slit by the knives as the arbors are rotated counter to one another, and

which is positioned over shim encircling the arbor, wherein the stripper ring has a

substantially uniform wall thickness and an internal diameter dimensioned for

allowing substantially free rotation of the stripper ring about the arbor in the

absence of the shim.

29. A slitting machine according to claim 28 wherein the stripper ring is substantially

freely rotatable about the shim.

30. A slitting machine according to claim 28 or 29 wherein the arbor carrying the at

least one stripper ring also carries at least one spacer ring encircling the arbor and

spacing a said knife along that arbor, and wherein the shim encircles the or at

least some of the spacer rings.

31. A slitting machine according to claim 30 wherein the at least one spacer ring

spaces a pair of said knives apart from one another along the arbor.

32. A slitting machine according to claim 30 or 31 wherein a plurality of said spacer

rings are arranged side by side relative to one another along the arbor, and the

spacer rings each have substantially the same wall thickness as each other.

33. A slitting machine according to any one of claims 28 to 32 wherein the shim

comprises a number of separate shim rings arranged side by side relative to one

another along the arbor and having substantially the same wall thickness as each

other.

34. A slitting machine according to any one of claims 28 to 33 wherein the arbor

carries a number of said stripper rings arranged side by side relative to one

other.

35. A slitting machine according to any one of claims 28 to 34 wherein the other said

arbor carries at least one stripper ring for pressing against the strip as the strip is

being slit.

36. A slitting machine according to any one of claims 28 to 35 wherein the strip is

metal strip.

37. A slitting machine incorporating a pair of opposed counter rotatable arbors

as the strip is passed between the arbors, wherein each of the arbors carries at

least one stripper ring respectively for pressing against the strip while being slit

by the knives as the arbors are rotated counter to one another, and wherein the stripper ring on one of the arbors is in an opposed relationship with the stripper

ring on the other said arbor and has a substantially uniform wall thickness and an

internal diameter dimensioned for allowing ring shaped shim to be received

thereunder around the one said arbor for altering a clearance between that stripper

5 ring and a slitting edge of a said knife carried by the one said arbor, and for

allowing substantially free rotation of that stripper ring in the absence of the

shim.

38. A slitting machine according to claim 37 wherein the one said arbor also carries

at least one spacer ring that encircles the one said arbor and spaces the said knife

o carried by that arbor therealong.

39. A slitting machine according to claim 38 wherein the at least one spacer ring

spaces a pair of said knives apart from one another along the one said arbor.

40. A slitting machine according to claim 38 or 39 wherein a plurality of said spacer

5 spacer rings each have substantially the same wall thickness as each other.

41. A slitting machine according to any one of claims 37 to 40 wherein the arbor

carries a number of said stripper rings arranged side by side relative to one

other.

0 42. A slitting machine according to any one of claims 37 to 41 wherein the strip is

metal strip.

43. A method of slitting different strip that differ in thickness from one to the next

utilising a slitting machine with shim under a stripper ring of an arbor of the slitting machine, substantially as hereinbefore described with reference to one or

more of Figures 6 to 9 of the accompanying drawings.

44. Use of at least one shim ring on an arbor of a slitting machine to alter a clearance

between a slitting edge of a knife of the arbor and a work face of a stripper ring

received around the arbor, substantially as hereinbefore described with reference

to one or more of Figures 6 to 9 of the drawings.

45. An arbor of a slitting machine wherein the arbor carries shim for altering a

clearance between a slitting edge of a knife of the arbor and a work face of a

stripper ring received around the arbor, substantially as hereinbefore described

with reference to one or more of Figures 6 to 9 of the drawings.

46. A slitting machine incorporating a pair of opposed counter rotatable arbors

provided with co-operating knives for slitting strip in a longitudinal direction of

the strip as the strip is passed between the arbors, wherein at least one of the

arbors carries at least one stripper ring having an internal diameter for allowing

ring shaped shim to be received around the arbor under the stripper ring to alter a

clearance between the stripper ring and a slitting edge of a said knife carried by

the arbor, substantially as hereinbefore described with reference to one or more of

Figures 6 to 9 of the drawings.