US3803661A

US3803661A - Apparatus for cleaning strip material

Info

Publication number: US3803661A
Application number: US00269807A
Authority: US
Inventors: V Salukvadze; V Musyakin
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-07-07
Filing date: 1972-07-07
Publication date: 1974-04-16
Anticipated expiration: 1991-04-16

Abstract

Strip material cleaning apparatus wherein the material being cleaned is positioned in the nips formed between rotary cleaning tools mounted for rotation on parallel shafts and respective back-up rolls, the latter being associated with drive means for positive forwarding of the material being cleaned, the rolls being rotated in the direction of the forwarding of the material, together with one half of the total amount of said parallel shafts, the other half of said shafts being rotated in the opposite direction. The shaft which is the first one of said parallel shafts in the direction of the forwarding of the material being cleaned is rotated in the course of a cleaning operation solely in the direction opposite to that of the forwarding of the material being cleaned.

Description

United States Patent Salukvadze et al.

11] 3,803,661 [451 Apr. 16,1974

[ APPARATUS FOR CLEANING STRIP MATERIAL [76] Inventors: ,Viktor Samsonovich Salukvadze,

' Parkovaya ulitsa, 42, kv. 53;

Vyacheslav Egorovich Musyakin, Sirenevy bulvar, 36, kv. 51, both of Moscow, USSR.

[22] Filed: July 7, 1972 [21] App]. No.: 269,807

[52] US. Cl. 15/77 [51] Int. Cl A46b 13/02 [58] Field of Search 15/77, 102; 51/DIG. 8, 51/22, 23, 78, 87 R [56] References Cited UNITED STATES PATENTS 2,278,944 4/1942 Quigley et al 15/77 2,321,179 6/1943 Boyer 15/77 3,245,102 4/1966 Gallmeyer et al. 15/77 Primary Examiner--Edward L. Roberts Attorney, Agent, or Firm-Holman & Stern 57 ABSTRACT Strip material cleaning apparatus wherein the material being cleaned is positioned in the nips formed between rotary cleaning tools mounted for rotation on parallel shafts and respective back-up rolls, the latter being associated with drive means for positive forwarding of the material being cleaned, the rolls being rotated in the direction of the forwarding of the material, together with one half of the total amount of said parallel shafts, the other half of said shaftsbeing r0- tated in the opposite direction. The shaft which is the first one of said parallel shafts in the direction of the forwarding of the material being cleaned is rotated in the course of a cleaning operation solely in the direction opposite to that of the forwarding of the material being cleaned.

3 Claims, 5 Drawing Figures PATENT EDAPR 16 I974 4 SHEET 1 BF 2 APPARATUS FOR CLEANING STRIP MATERIAL The invention relates to the techniques of cleaning the surface of a material, and, more particularly, it relates to apparatus for cleaning strip material.

The invention can be employed to utmost advantage for cleaning sheet material practically of any thickness, particularly of thin sheets having the thickness within a range from 0.2 mm to 4.0 mm.

There are known apparatus for cleaning sheet material positively forwarded through the nips formed by rotary cleaning tools mounted on parallel shafts and by the respective back-up rolls cooperating with the tools. (See, for example, US. Pat. No. 2,907,151, 1959).

In these known apparatus the strip material being cleaned is positively forwarded by at least two spaced pairs of pulling rollers, the rotary cleaning tools and their respective back-up rolls being arranged in the space between these two pairs. The back-up rolls are freely rotatable about their shafts and are rotated, as the strip material is being positively forwarded, by the friction forces between the material being cleaned and the peripheries of these rolls.

These known apparatus provide for cleaning of a material having a thickness sufficient for maintaining longitudinal stability of this material against the action of the friction forces developed in the course of a cleaning operation.

A disadvantage of these known apparatus is the fact that they are virtually incapable of effecting continuous cleaning of thin sheets (the thickness being from 0.2 to 0.5 mm) along the entire length of the sheets.

A reason for this fact is that as the trailing edge of the material leaves the nip of the first, or upstream (in the direction of the forwarding of the material) pair of the pulling rollers, the material, when it is in the form of thin sheets having relatively low rigidity, no longer maintains its longitudinal stability against the friction forces developed in the course of a cleaning operation under the action of the rotating cleaning tools either in the area intermediate of the axis of the shaft carrying pulling rollers, in case the direction of the rotation of the last-mentioned shaft is that of the direction of the forwarding of the sheets, or else in the area intermediate of the axis of the first pair of pulling rollers and the axis of the shaft carrying these rotating cleaning tools, in case the direction of the rotation of this shaft is opposite to the direction of the forwarding of the sheets. In both cases only a part of the length of a sheet can be cleaned.

Furthermore, in these known apparatus the spacing between the two pairs of pulling rollers limits the permissible range of the lengths of sheets to be cleaned, because the length of a sheet is substantially greater than this spacing.

It is the principal object of the present invention to provide an apparatus for cleaning strip material, wherein this material is positively forwarded and the shafts carrying the rotary cleaning tools is rotated in such directions, that the apparatus is capable of highquality cleaning not only of sufficiently thick strip material, but also of continuous cleaning of thin sheets of practically any thickness.

This and other objects are attained in an apparatus for cleaning strip material positively forwarded through the nips formed between rotary cleaning tools mounted on parallel shafts and the respective back-up rolls, each said back-up roll being mounted in opposition to the respective one of said shafts, in which apparatus, in accordance with the invention, all said back-up rolls are associated with drive means and are adapted for rotation in the direction of the forwarding of the strip material being cleaned, together with one half of the total amount of said parallel shafts carrying thereon said rotary cleaning tools, the other half of the total amount of said parallel shafts being rotated in the opposite direction; one of said parallel shafts, which is the first one in the direction of the forwarding of said strip material being cleaned, being adapted for rotation in the course of a cleaning operation solely in a direction opposite to the direction of the forwarding of said material being cleaned.

With the apparatus having been designed in the lastdescribed manner, the strip material cleaned thereby maintains, as it is being forwarded, adequate longitudinal stability over the area intermediate of the shafts carrying thereon the rotary cleaning tools, which provides for high-quality cleaning not only of strip material, but also of individual thin sheets of practically any thickness.

To provide for cleaning of individual, different lengths of material, it is advisable that at least one of said parallel shafts carrying said cleaning tools and the respectively arranged one of said back-up rolls should be mounted for adjustment in the direction of the forwarding of said material being cleaned.

It is further advisable, in order to ensure high-quality cleaning of strip material and sheets, particularly, those having a thickness in excess of 2.0 mm, that each said shaft should carry thereon said rotary cleaning tools adapted for rotation in opposite directions and so arranged relative to one another that the linear speed of said material being cleaned in the areas of the contact thereof with said back-up roll is the same, the total width of said tools rotated in one of said opposite directions being at least equal to the total width of said tools rotated in the other one of said opposite directions, all said tools on all said parallel shafts being so arranged that the respective widths thereof successively and altematingly span the total width of said material being cleaned.

In case the total width of said tools rotated in said one of said opposite directions is greater than the total width of said tools rotated in said other one of said opposite directions, the difference between said total widths should not be in excess of a value determined from the expression: ,7

where f is the factor of the slipping friction between said material being cleaned and said back-up roll;

F is the factor of friction drag or pull exerted by said cleaning tool upon said material being cleaned;

B is the width of the material being cleaned.

It is highly essential, in order to solve an important problem of combining a high quality of the cleaning with a high productivity of apparatus, that said rotary cleaning tools should be in the form of rotary cutting tools including each a plurality of radially extending lengths of wire, said lengths having the ends thereof, disposed internally of said tools, connected to one another, said lengths further having the lateral sides thereof adjacent to said connected ends pressed to one another, the opposite free ends of said lengths of wire forming a common cutting surface of said tool in the shape of a body of rotation, the ratio of the total area of the faces of said free ends of said lengths to the total area of said cutting surface being within a range from 0.2 to 0.9.

The present invention will be further described in connnection with several embodiments thereof, with reference being had to the appended drawings, wherein:

FIG. 1 shows schematically a plan view of an apparams for cleaning strip material, having two parallel shafts carrying rotary cleaning tools, in accordance with the invention;

FIG. 2 is a sectional view taken along line IIII of FIG. 1;

FIG. 3 is a front view of an apparatus for cleaning strip material wherein, in accordance with the invention; a shaft and the respective back-up roll are adjustable in the direction of the forwarding of the material being cleaned (the material being shown in crosssection);

FIG. 4 is a partly broken away front view of an apparatus for cleaning strip material wherein, in accordance with the invention, each shaft carries cleaning tools connected for rotation in opposite directions; and

FIG. 5 is a front view of the apparatus illustrated in FIG. 4, with the material being cleaned shown in crosssection. I

Referring now in particular to the appended drawings, the herein disclosed apparatus for cleaning strip material includes a plurality of parallel shafts (two shafts in the presently described embodiment) 1 and 2 (FIG. 1) carrying thereon rotary cleaning tools 3 and 4, the strip material being positively forwarded intermediate these cleaning tools and their respective backup rolls 5 mounted in opposition to the respective shafts.

In accordance with the present invention, all the back-up rolls 5 (FIG. 2) are driven ones, the rolls being positively rotated in. the direction indicated by the arrow A, one half of the parallel shafts carrying thereon the cleaning tools being rotated in the same direction A, and the other half of these parallel shafts being rotated in the opposite direction indicated by the arrow line C (FIG. 1). g

(Symbols B and b will be used hereinafter to indicate, respectively, the lateral width of the material being cleaned and the width of the cleaning tools).

The shaft 1 which is the first or up-st-ream one in the direction of the forwarding of the material 6 is rotated throughout the cleaning operation solely in the direction indicated by the arrow line C, in opposition to the direction of the travel of the material being cleaned.

The shafts l and 2 are journalled in bearings 7 mounted on supports 8 included in the apparatus. The back-up rolls 5. (FIG. 2) are journalled in bearings 9 mounted on a cross bar 10 movable in guideways 11 under the action of the back-up roll vertical adjustment actuator 12. This vertical adjustment of each one of the back-up rolls 5 is necessary for establishing a desired value of contact pressure between the strip material 6 being cleaned and the respective rotary cleaning tool.

In the presently described embodiment each cleaning tool-carrying shaft is independently rotated by an electric motor 13 associated therewith. Each back-up roll 5 is likewise independently rotated by an associated electric motor 14. The independent driving motors offer independent control of the speed of the rotation of the cleaning tool and of its respective back-up roll.

The herein disclosed apparatus operates as follows. The motors 13 driving the respective shafts 1 and 2 are energized, and the motors l4 driving the respective back-up rolls are energized, too,

Rotation from the motor 13 is transmitted to the input shaft of a reducing gear 15, and from the output shaft of this reducing gear rotation is further transmitted by any suitable known means to the respective shafts l and 2 carrying the cleaning tools 3 and 4. The shaft 1 is rotated in the direction C, i.e., in opposition to the travel of the strip material 6, whereas the shaft 2 is rotated in the direction A, i.e., in the direction of the travel of the strip material 6.

Rotation from each motor 14 is transmitted to the input shaft of a reducing gear 16, and from the output shaft of this reducing gear rotation is transmitted by any suitable known means to the respective one of the back-up rolls 5 which are thus rotated in the direction A of the travel of the strip material 6.

The strip material 6 is forwarded in the direction A by the first, or upstream one of the back-up rolls 5. As the leading edge of the strip material 6 engages the second, or downstream one of the back-up rolls 5, the back-up roll vertical adjustment actuators 12 are operated, whereby the strip material 6 is pressed by the back-up rolls 5 against the respective rotating cleaning tools 3 and 4.

The design of the herein disclosed apparatus ensures that the strip material 6 being cleaned, as it is being positively forwarded by the back-up rolls 5, retains its longitudinal stability throughout the area between the two parallel shafts l and 2, whereby the apparatus is capable of continuous, high-quality cleaning not only of strip material and thick sheets, but also of thin sheets of any thickness ranging from 0.2 mm to 4.0 mm.

Alternatively, the herein disclosed apparatus may be operated, as follows.

The strip material 6 is forwarded in'the direction indicated by the arrow line A by the upstream back-up roll 5. As the leading edge of the strip material 6 engages the second, or downstream back-up roll 5, the 10 tuators 12 are operated to adjust vertically the two back-up 5, whereby the latter press the strip material 6 toward the respective cleaning tools 3 and 4. In this way there is cleaned a length of the strip material 6, equal to double distance between the axes of the shafts l and 2. Then the peripheral linear speed of the rotating cleaning tool 4 is gradually reduced to the linear speed of the forwarding of the material 6, whereby the cleaning tool starts acting as a pulling transport roller, i.e., in this case the rotating cleaning tool together with its respective back-up rool effect positive forwarding of the material being cleaned. Cleaning of the remaining length of the strip material 6, i.e., of the length upstream of the first roll 5, is effected by the cleaning tool 3.

In this way, too, there is ensured continuous cleaning not only of strip material and relatively thick sheets, but of thin sheets, e.g., with thickness ranging from 0.2 mm to 4.0 mm, as well.

To clean successive individual lengths of a material, it is advisable, in accordance with the invention, that at least one of the two parallel shafts (the shaft 2 in the presently described embodiment) carrying the rotary cleaning tools and its respective back-up roll 5 should be mounted for adjustment longitudinally of the direction of the forwarding of the material 6 being cleaned.

Such longitudinal adjustment is made possible by the supports 8 carrying the bearings 7 of the shaft 2 and the crossbar 10 carrying the bearings 9 of the respective back-up roll 5 being mounted on a longitudinally movable plate 17. The same plate 17 in this case has mounted thereon the drive effecting rotation of the shaft 2 carrying the cleaning tool 4, as well as the drive of the respective back-up roll 5.

The plate 17 can be reciprocated along tracks 18 longitudinally of the direction of the arrow A with the help of an electric motor 19.

With the herein disclosed apparatus constructed in the last-described manner, its operation ability be comes broadened, i.e., longitudinal adjustment of the plate 17 in the direction of the arrow line A, i.e., in the direction of the forwarding of the material 6 being cleaned, provides for continuous cleaning of sheets of various lengths.

Let us now consider another embodiment of the present invention, wherein the parallel shafts 1 and 2 (FIG. 4), in accordance with the invention, carry

rotary cleaning tools

20, 21 and 22, 23 rotated in the opposite directions and so arranged relative to one another that the linear speed of the material 6 being cleaned in the areas of the engagement thereof with the back-up rolls 5 should be the same. The cleaning tools 20 are nonrotatably mounted on the shaft 1 for rotation together therewith, while the cleaning tools 21 are mounted for free rotation about the shaft 2 with the help of their bearings 24 and are positively rotated in a direction opposite to that of the forwarding of the material 6.

The cleaning tools 22 are mounted for free rotation about the shaft 1 with the help of their respective bearings 24 and are rotated in the direction of the arrow A, i.e., in the direction of the forwarding of the material 6 being cleaned, while the cleaning tools 23 are nonrotatably mounted on the shaft 2 for rotation together therewith, i.e., in the direction of the arrow A.

In this case the total lateral width Eb, of the

cleaning tools

20 and 21 rotating in one direction indicated by the arrow C should be not below the total lateral width Zb of the

cleaning tools

22, 23 rotating in the opposite direction indicated by the arrow A.

The

cleaning tools

20 and 21, 22 and 23 are mounted in a staggered relationship on the respective ones of the shafts l and 2, so that the lateral width thereof successively and alternatingly spans the entire lateral width B of the material 6 being cleaned.

In the presently described embodiment of the invention the rotation of the

cleaning tools

22 and 21 that are freely rotatable, respectively, about the shafts l and 2 is effected by an electric motor 13 (FIG. 5) from which rotation is transmitted to the input shaft of a reducing gear 15, from the output shaft of which rotation is transmitted through a gearing including two bevel gear couples 25 and 26. In each bevel gear couple 25 the driving gear is non-rotatably mounted on the respeetive one of the shafts 1 and 2, and the driven gear is rigidly coupled to the driving gear of the bevel gear couple 26. The driven gear of the bevel gear couple 26 is non-rotatably mounted on an intermediate shaft 27 journalled for rotation in bearings 28 mounted on the supports 8 (FIG. 4) of the apparatus.

The intermediate shaft 27 (FIG. 5) if drivingly connected with the

cleaning tools

21 and 22, mounted for free rotation about the respective shafts 2 and 1, by chain transmission means 29.

The last described embodiment of the present invention is operated as follows. I

The electric motors 13 (FIG.'4) are energized to drive the shafts l and 2, and the electric motors 14 are energized to drive the back-up rolls 5. The shaft 1 is thus rotated in the direction indicated by the arrow line C, i.e., in opposition to the forwarding of the strip material 6, whereas the shaft 2 is rotated in the direction indicated by the arrow line A, i.e., in the direction of the forwarding of the strip material 6.

As' the leading edge of the strip material 6 engages the roll 5 which is the first, or upstream one in the direction of the progress of the material 6, the actuator 12 (FIG. 5) is operated to effect vertical adjustment of this back-up roll 5, whereby the material 6 is pressed by the last-mentioned roll to the

respective cleaning tools

20 and 22. In this way a part of the total width B of the material 6 is cleaned. Subsequently, when the leading edge of the strip material 6 engages the second back-up roll 5, the respective actuator 12 is operated to effect vertical adjustment of this second roll 5, whereby the latter presses the strip material 6 to the

respective'cleaning tools

21 and 23, in which way the rest of the lateral width of the strip material is cleaned.

With the herein disclosed apparatus constructed in accordance with the last-described embodiment, there can be effected high-quality continuous cleaning of strip material and sheets of any length, as well as cleaning of relatively thin sheets which in this case retain complete (i.e., both longitudinal and lateral) stability against deformation by the friction forces exerted thereupon by the rotating cleaning tools.

In case the total width 2b, of the

tools

20 and 21 rotating in one direction is in excess of the total width Eb of the

tools

22 and 23 rotating in the opposite direction, the difference between these two total widths Ab should be, in accordance with the invention, not in excess of the value of Ab, defined from the formula:

where f is the factor of slipping friction between the material being cleaned and the back-up roll; F is the factor of friction or drag between the cleaning tool and the material being cleaned; B is the lateral width of the material being cleaned.

Let us now describe an example.

A strip material 6 having lateral width B equal to 2,000 mm is treated by the rotating cleaning tools 20, 22 (FIG. 4) mounted on the shaft 1 and

tools

21, 23 mounted on the shaft 2.

The

tools

20 and 21 have their width b, and are rotated in the direction of the arrow C, while the

tools

22 and 23 have their total width b and are rotated in the direction of the arrow A.

In accordance with the invention, the

tools

20, 21, 22, 23, 22, 21 and 20 successively and alternatingly span the entire lateral width B of the material being cleaned, i.e.,

2b 21, B, i

ro) 2(1) m (1) where 1 1(1) ltll):

where 2b, is the total width of the tools rotated in the direction of the arrow C about the shaft l; 271 is the total width of the tools rotated in the direction of the arrow C about the shaft 2. Similarly, let us express the total lateral width Eb of the tools rotated in the direction of the arrow A in the form:

where Eb is the total width of the tools rotated in the direction of the arrow A about the shaft 1; Eb is the total width of the tools rotated in the direction of the arrow A about the shaft 2.

The lateral width B of the strip material 6 is jointly spanned by the width of the tools mounted about the shaft 1 and the width of the tools mounted about the shaft 2, i.e.,

B u) an, 7

and

BU) m) 2(1) un um zun where B is one part of the total lateral width of the strip material 6, spanned by the total width Ela of the tools 20 and by the total width Eb of the tools 22, mounted about the shaft 1;

B is the other part of the lateral width of the mate- I rial 6, spanned by the total width Eb of the tools 21 and by the total width Eb of the tools 23, mounted about the shaft 2.

Let us presume that B B 3/2; B B 1,000 mm and that the total width 2b, of the tools 20 mounted about the shaft 1 and rotated in one direction is in excess of the total width Zb of the tools 22 mounted about the same shaft 1, but rotated in the opposite direction by a value AEb i.e.,

A212 is the difference between the total widths of the

tools

20, 22 mounted on the shaft 1.

in accordance with the invention, the value of the A21) should be not in excess of the value Ab flF Lfir further presume that tiia'a'rr'eracarz between thetotal widths of the

tools

20, 22 mounted about the shaft 1 equals: A212 180 mm. With Ab 0.1 y 15 :50mn51/0 1,000

Bu mm tools

20, 22 mounted about the shaft 1 equals:

Azbu mm.

Let us then determine from the expressions 5 and 7 '7 Let us now pr esurhe that the difference Aib of the the values of Zb and Zb 3O m) (1) UO/ 20) ro) m- Now we are able to calculate that: with F= 0.75 2b, =f(l,000 l)/2 590 mm.

Ebgu mm. with F= 0.30 Eb (1,000 480)/2 740 mm Zb 740 480 260 mm. 7 Let us presume (for the shaft 2) that the total width Zb ofthe tools 21 mounted about the shaft 2 and rotatedin one direction is equal to the total width Erotated in b of the tools 23 mounted about the same shaft 2, but rotated in the opposite direction, i.e.:

and then the difference AEb between the total widths of the

tools

21 and 23 becomes equal to 0.

Let us further calculate, for the shaft 2 in accordance with the invention the value un f/ un- From the

expressions

6 and 8 let us determine 217 and Ebzun: fll!) un an); 2 um un- Now we are able to calculate that: with F 0.75

Zb 1 mm,

Eb 1,000 500 mm 500 mm, and likewise with F 0.30

Eb 500 mm Zb 500 mm.

We can see from the abovesaid that in the example that is being described, with the total width 2b, of the tools 20 equalling 590 mm, and the total width Eb of the tools 22 equalling 410 mm, the above tools being mounted about the shaft 1, and with the total width Zb of the tools 21 equalling 500 mm and the total width Eb of the tools 23 equalling 500 mm, these tools being mounted about the shaft 2, the strip material 6 being cleaned (at a predetermined speed, without the material slipping on the back-up roll) may have the width ranging from 2,000 mm to 1,640 mm, when F 0.75, or else from 2,000 mm to 1,400 mm, when F 0.30, and that without varying the width of the cleaning tools mounted about the shafts 1 and 2.

Therefore, it can be seen from the abovesaid that the herein disclosed apparatus offers wide operating capacities and facilitated performance.

The herein disclosed apparatus can employ effectively for the cleaning tools thereof rotaty cutting tools with radially arranged lengths of wire, the lengths of wire being connected to one another adjacent to one end thereof, the lengths being pressed to one another adjacent to these connected ends by their lateral surfaces, the opposite free ends of these lengths of wire making up a common cutting surface of the tool in the form of a body of rotation, the ratio of the tool area of the faces of these free ends of the lengths of wire to the total area of the cutting surface of the tool being within a range from 0.2 to 0.9.

The employment of the abovespecified tools broadens still further the operational abilities of the herein disclosed apparatus and considerably improvesits performance.

What we claim is:

1. Apparatus for cleaning strip material, comprising: in combination, a plurality of rotary cleaning tools, at least one pair of parallel shafts carrying said cleaning tools; a plurality of back-up rolls for cooperation with said cleaning tools, each one of said back-up rolls being disposed in opposition to a respective one of said parallel shafts carrying said cleaning tools to form nips therebetween, said nips being spaced longitudinally from each other; said back-up rolls being associated with drive means for effecting positive forwarding of said material from a first nip to and through the next nip said back-up rolls being adapted for rotation in the direction of the forwarding of said material, one half of the total of said parallel shafts carrying said cleaning tools also being adapted for rotation in the direction of the forwarding of said material, the other half of said total of said parallel shafts being adapted for rotation in a direction opposite to the forwarding of said material; one of said parallel shafts carrying said cleaning tools, which is the first one in said direction of said forwarding of said material, being adapted for rotation in the course of a cleaning operation only in a direction opposite to said direction of said forwarding of said material.

2. An apparatus as claimed in claim 1, wherein at least one of said parallel shafts carrying said cleaning tools and the respective one of said back-uprolls arranged for cooperation therewith, are mounted for adjustment in the direction of said forwarding of said material.

3. An apparatus as claimed in claim 2, wherein each one of said parallel shafts carries thereon said cleaning tools rotated in opposite directions to each other and so arranged in relation to one another that the linear speed of said material in the areas of the contact thereof with the respective one of said back-up rolls is the same, the total lateral width of those of said tools that are rotated in one of said opposite directions being essentially equal to the total width of those of said tools that are rotated in the other of said opposite directions,

all tools on said parallel shafts being so arranged with respect to each other that the respective lateral widths thereof span the total width of said material.

Claims

2. An apparatus as claimed in claim 1, wherein at least one of said parallel shafts carrying said cleaning tools and the respective one of said back-up rolls arranged for cooperation therewith, are mounted for adjustment in the direction of said forwarding of said material.

3. An apparatus as claimed in claim 2, wherein each one of said parallel shafts carries thereon said cleaning tools rotated in opposite directions to each other and so arranged in relation to one another that the linear speed of said material in the areas of the contact thereof with the respective one of said back-up rolls is the same, the total lateral width of those of said tools that are rotated in one of said opposite directions being essentially equal to the total width of those of said tools that are rotated in the other of said opposite directions, all tools on said paralLel shafts being so arranged with respect to each other that the respective lateral widths thereof span the total width of said material.