US3823593A

US3823593A - Method of rolling metal sheet articles between the driven rolls of the roll mill

Info

Publication number: US3823593A
Application number: US00245250A
Authority: US
Inventors: L Ageev; V Vydrin
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-06-26
Filing date: 1972-04-18
Publication date: 1974-07-16
Anticipated expiration: 1991-07-16
Also published as: US3709017A

Abstract

The present invention relates to a method of rolling metal sheet articles between cooperating driving and driven rolls of rolling mills, the rolls being rotated in opposite directions at different peripheral speeds. A stretching strain is applied to the delivery section of the article, and the process is effected with the ratio between the peripheral speeds of the rolls being not less than the reduction of the article being rolled, and with the rate of travel of the delivery end of the article being equal to the peripheral speed of the driving roll that is rotated at a greater speed. The invention also discloses mills for effecting the present method, which are provided with means for insuring the required ratios between the peripheral speeds of the rolls.

Description

United States Patent. [191 Vydrin et al.

[ July 16, 1974 METHOD OF ROLLING METAL SHEET ARTICLES BETWEEN THE DRIVEN ROLLS OF THE ROLL MILL [76] Inventors: Vladimir Nikolaevich Vydrin, ulitsa Svobody, 139, kv. 7; Leonid Matveevich Ageev, ploschad MOPRa, 2, kv. 33, both of Chelyabinsk, USSR.

[22] Filed: Apr. 18, 1972 [21] Appl. N0.: 245,250

Related U.S. Application Data [62] Division of Ser. No. 836,851, June 26, 1969, Pat. No.

OTHER PUBLICATIONS Status of ContactBend-Stretch Rolling, by L. F. Coffin, Jr., Journal of Metals, August, 1967.

Primary ExaminerMilton S. Mehr Attorney, Agent, or FirmWaters, Roditi, Schwartz & Nissen [5 7 ABSTRACT The present invention relates to a method of rolling metal sheet articles between cooperating driving and driven rolls of rolling mills, the rolls being rotated in opposite directions at different peripheral speeds. A stretching strain is applied to the delivery section of the article, and the process is effected with the ratio between the peripheral speeds of the rolls being not less than the reduction of the article being rolled, and with the rate of travel of the delivery end of the article being equal to the peripheral speed of the driving roll that is rotated at a greater speed. The invention also discloses mills for effecting the present method, which are provided with means for insuring the required ratios between the peripheral speeds of the rolls.

11 Claims, 10 Drawing Figures METHOD OF ROLLING METAL SHEET ARTICLES BETWEEN THE DRIVEN ROLLS OF THE ROLL MILL This application is a divisional application of Ser. No. 836,85l, filed June 26, 1969, now US. Pat. No. 3,709,017.

The present invention relates to a method of rolling metal sheet articles, particularly strips, bands, sheets, foil, preferably in the cold state, and to mills for effecting such method.

The term rolling as employed herein and below is to be understood as comprising also temper rolling and straightening of sheet articles.

Commonly known in the art are methods of rolling sheet articles, according to which the latter are reduced in rolls that are rotated in opposite directions with the same or different peripheral speeds with a stretching strain being applied to the front and back ends of the article or only to the front end thereof. In the process of rolling in accordance with such methods on the surfaces of each roll that contact the article being rolled there originate two zones of slippage a zone of slippage on the entry side and a zone of slippage on the delivery side, the forces of friction within these zones being directed towards each other. The forces of friction are quite considerable and hinder the deformation of metal in the direction of rolling (drawing) the article, great efforts being thus required for deforming the metal.

This fact is especially manifested in cold rolling of sheet articles made of sheets and alloys that are difficult to deform, the specific pressures exerted by the rolled metal onto the rolls reaching 200 kg/mm and over.

Attempts were made to improve the known methods of rolling sheet articles. Thus, a method was proposed, according to which plastic deformation of metal was attained due to the action of normal, stretching and bending strains imposed on the article. In particular, such a method is described in Journal of Metals, August l967, in the article entitled Status C. BdS. Rolling.

The known method of rolling was effected on mills of different designs: those with two driven rolls and with one floating roll disposed between the driven rolls; with three driven and two floating rolls, each of the two floating rolls being disposed between two adjacent driven rolls; with two driven work rolls, two idle support rolls and with one floating roll disposed between the work rolls. The diameter of the floating rolls was much smaller than that of the driven rolls. The ratio between the peripheral speeds of the driven rolls was equal to the drawing of the article which consecutively encompassed the driven and floating rolls. Due to the employment of floating rolls of a small diameter and to the plastic bending of the article around the rolls it was possible to reduce the pressure exerted onto the rolls and to increase the reduction of the article during one pass. This method could be employed for temper rolling and straightening of articles.

However, with the application of the known method the speed of rolling proved to be limited, since the number of revolutions of the floating roll is very great causing it to become rapidly heated. Moreover, it is difficult to make a small-diameter floating roll adequately rigid, this fact involving additional non-uniformity of the thickness of the article because of clearances originating when the floating roll is self-adjusted with respect to the driven rolls.

It is an object of the present invention to improve the method of rolling metal sheet articles between the driven rolls of the mill by selecting optimal ratios be tween the peripheral speeds of the driving and driven rolls in each adjacent pair, and also to provide improved rolling mills for effecting the proposed method.

Proposed in the present invention is a method of rolling metal sheet articles between driving and driven rolls of the mill, according to which the rolls of the adjacent pair are rotated in opposite directions at different peripheral speeds and stretching strains being applied to the delivery section of the article. According to the invention, the rolling is effected with a ratio between the peripheral speeds of the rolls, which is not less than the reduction of the article, and with the speed of motion of the delivery end of the article equal to the peripheral speed of the driving roll, that is, of the roll which rotates with a speed greater than that of the driven roll.

In this case the influence of the forces of friction in the zone of deformation on the process of deformation is excluded, since the forces of friction on the opposite contact surfaces of both rolls are equal and oppositely directed. The speed of metal of the article being rolled in the place of contact with the driving roll will be smaller than the peripheral speed of the driving roll, while the speed of metal of the article being rolled will exceed that of the driven roll. Thereby the pressure exerted by the metal onto the rolls is considerably 'diminished.

It is desirable, that the stretching strains be created simultaneously at the leading and trailing ends of the article, since stretchings originating therein contribute to still greater reduction of the pressure of metal onto the rolls.

It is expedient, that the stretching strain at the delivery section of the article should be created by virtue of the article encompassing the driving roll that is rotated with a greater speed. In this case due to stretching on the arc of the encompassing the roll by the article there originate forces of friction of rest, which fact is conducive to the reduction of the stretching strain required and to stabilization of the process.

The most optimal version of the embodiment of the present method is accomplished in the case when the stretching strains on the entry and delivery sections of the article are created by the article successively encompassing the driven and driving rolls, and the ratio between the peripheral speeds thereof is maintained to be equal to the'reduction of the article between said rolls. The pressure of metal will be reduced still further, and the process will be much more stable.

The friction between the driving roll and the rolled article in the deformation zone should be made to exceed that between the driven roll and the article. Then the required stretching strain at the delivery section will be smaller.

In case when the rolling is effected through a plurality of alternating driving and driven rolls, the article can encompass only the middle rolls, the extreme rolls remaining free. Then it becomes possible to employ the support rolls for diminishing the deflection of the extreme rolls.

The present method can be carried out on rolling mills of different designs.

For carrying the method of rolling the article with tensioning the front end thereof, a mill is proposed that comprises rolls rotated with different peripheral speeds in opposite directions and at least one group of rolls for tensioning the front end of the article in the course of rolling. According to the invention, in the mill the driving roll is kinematically associated with the group of tension rolls so that said rolls rotate with the same peripheral speed as the driving roll.

For effecting the method of rolling with a simultaneous tensioning of the front and back ends of the arti- The carrying out of the method of rolling the article with tensioning its front and back ends by the article encompassing the driven and the driving rolls may be effected on a mill that comprises driven rolls rotated with different peripheral speeds in opposite directions and reels for tensioning the ends of the article during rolling. In accordance with the invention the reel that creates tension at the leading end of the article is arranged from the side of the driven roll, and the reel that creates tension of the trailing end of the article is arranged from the side of the driving roll.

When rolling the article with tensioning of only the leading end thereof a mill can also be employed that has a plurality of consecutively arranged stands with driving and driven rolls rotated with different peripheral speeds in opposite directions and a means for tensioning the front end of the article duringrolling. In this mill, according to the invention, the driving roll of each preceding stand is kinematically associated with the driven roll of the subsequent stand.

The method of rolling the article with tensioning the front and back ends thereof by way of consecutive encompassing of the rolling rolls is effected by means of a mill that comprises driving and driven rolls rotated at different peripheral speeds and in opposite directions, means for tensioning the article from both ends during rolling, and presser means for adjusting the distance between the axes of rotation of the rolls. According to the invention, the presser means are disposed at both sides of each roll.

The mills proposed herein are relatively simple in design. They can be produced by modification of conventional mills adapted for rolling sheet articles.

The invention will now be explained by the description of exemplary embodiments thereof with reference to the accompanying drawings.

In the drawings:

FIG. 1 shows a diagrammatic view of a conventional method of rolling sheet articles in driven rolls;

FIG. 2 is a diagrammatic view of a method of the present invention for rolling sheet articles in driven rolls;

FIG. 3 is a diagrammatic view of a proposed method wherein the front tension is created by the article en compassing the driving roll;

FIG. 4 is a diagrammatic view of a proposed method wherein the front and back tension of the article is created by the article encompassing the driven and the driving rolls of the entire row;

FIG.-5 is a diagrammatic view of a proposed method wherein the article encompasses only the middle driven and driving rolls of the row;

FIG. 6 shows a mill for effecting the method of rolling with the article tensioned from both ends by means of rolls kinematically associated with the mill rolls;

FIG. 7 shows a top cut-away view of the mill according to FIG. 6, which illustrates the kinematic connection of tension rolls with the driven rolls of the mill;

FIG. 8 shows a mill with two reels for tensioning from both ends the article that encompasses both rolls;

FIG. 9 shows a mill made as a plurality of consecutively arranged stands, wherein the driving roll of the preceding stand is kinematically associated with the driven roll of the subsequent stand; and

FIG. 10 shows a mill-with a plurality of driven rolls that are encompassed by the article in the course of rolling and with presser means for adjusting the distance between the axes of the rolls.

For a better understanding of the essence of the present invention we shall first analyze the known method of symmetric rolling without tensioning of the article involved.

When implementing the conventional method, the peripheral speeds V and V of the rolls a and b (FIG. 1) are equal, critical angles 'Yu and Yb that determine the zones of slippage on the entry side of the metal of the article m and on the delivery side thereof relative to the rolls a and b being also equal. With an increase of the peripheral speed V of the roll a (which will be termed hereafter the driving one) the angle 'y decreases, since the driving roll a starts delivering greater power into the deformation zone. At the same time the angle 7 increases, and the power delivered by the driven roll b in to the deformation zone diminishes.

At a certain ratio between the speeds V, and V,, the angle 7 becomes zero. At this moment the zone of slippage on the entry side of metal m takes place over the entire contact surface of the driving roll a, with the exception of the place (plane 00 of the metal delivery, where its speed V is equal to the peripheral speed V of the driving roll a.

If the rotational speed of the roll a is increased still further, it will start slipping with respect to the metal.

A further mismatch between the peripheral speeds V and V,, of the rolls a and b is possible when an additional power is supplied into the deformation zone, which is necessary for running a stable process without slippage of the roll a relative to the metal.

This can be achieved, in particular, by applying a stretching strain P, to the front end (delivery section) of the article (FIG. 2). With VU/Vb A (where )t is the reduction of the article per pass) and V, V we obtain 3 a where a, is the angle of nip of the rolls a and b, that is, on the surface of contact of the driven roll with the article there will be leading of metal,

while on the contact surface of the driving roll a the metal will lag.

The diagram presented in FIG. 2 illustrates the effect of forces of friction in the deformation zone with the method of rolling of the present invention on the deformation process: tangent strains 7,, and n, are equal and oppositely directed, whereby the backing-up action of the forces of friction onto the deformed volume of metal is excluded, and the pressure exerted on the rolls is considerably diminished as compared to the conventional method of rolling.

For minimizing the pressure of metal onto the rolls a and b, stretching strains P and P are created simultaneously on the front and back ends of the article, respectively.

To reduce the necessary tension of the front end of the article m and to stabilize the process of rolling, the article is made to encompass the driving roll a (FIG. 3) so as to utilize for tensioning the force of friction of rest on the arc of encompassing. Under the terminology friction of rest we understand here that the article and the roll move without slippage.

Since the force of friction of rest on the arc of encompassing may vary within wide limits with the tension of the end of the article remaining the same, the process will run more steadily.

The most favourable will be the case, when the stretching strains are created at both ends of the article by making it encompass each roll 1, 2, and 3 as shown in FIG. 4, so that the process can be effected on two and more rolls. The article m is reduced between each preceding and subsequent rolls 1,2 and 3 in the direction of rolling, and the ratio between the peripheral speeds V V and V of each adjacent pair of rolls is equal to the reduction A of the article m therebetween, that IS, V2/V1: V V2 A2; V3/V1= A1 M, where )\1 and A are the values of reduction the article between the rolls 1 and 2 and 2 and 3, respectively. All what has been stated above with respect to the proposed method applied to the given case as well.

It is always expedient, that the pressure between the article and the drivingroll created within the deformation zone should be greater, than the pressure between the article and the driven roll. This can be achieved by varying the force of friction through appropriately selecting the surface finish of the rolls, or by feeding grease into the deformation zone. Then it will be possible to diminish the stretching strain P, effective on the front end of the article.

Sometimes, when rolling the article through a great number of rolls (more than two), it is preferable to make the article encompass only the middle rolls 4 and 5 (FIG. 5), leaving the extreme rolls 6 and 7 free. This is done whenthe extreme rolls are to be protected against deflection under the pressure of metal, or such deflection is to be reduced, additional support rolls being installed in such a case for the extreme rolls (the support rolls being not shown).

The above-described embodiments of the method can be carried out on mills of different designs.

In particular, the embodiments where rolling is effected with tensioning the leading and trailing ends of the article without encompassing the rolls may be effected on a mill shown in FIGS. 6 and 7.

The mill has a housing 8 in which at least two driven work rolls 9 and 10 are mounted, as well as support rolls 11 which through their chocks l2 interact with a presser means 13 that provides a required clearance between the rolls 9 and 10.

At each side of the housing 8 there are disposed reels l4 and 15 which are used, respectively, for winding and unwinding the article m which is passed between the rolls 9 and 10.

For tensioning the both ends of the article two groups housing 8.

The group 16 is kinematically associated with the driven roll 9 by means of gear trains 18 (FIG. 7), and the group 17 is kinematically associated through gear trains 19 with the driving roll 10, each of the rolls 9 and 10 being rotated from one of individual drives 20 and 21 at different peripheral speeds and in opposite directions. The gear trains 18 and 19 are so selected, that the peripheral speed of the rolls kinematically associated therewith, and the ratio between the speeds of the rolls 9 and 10 is made equal to the reduction of the article.

Slippage of the article m relative to the

groups

16 and 17 of the rolls is prevented by virtue of additional tensioning of the ends of the article by the

reels

14 and 15.

The method of rolling with the article being tensioned from both ends and encompassing the rolls can be effected on a mill as represented in FIG. 8.

In a housing 22 of the mill there are disposed, respectively, driving and driven work rolls 23 and 24 that are rotated at different peripheral speeds and in opposite directions, but in such a manner, that the ratio between their speeds remains equal to the reduction of the article rn, the roll 23 being the driving one and rotating at a greater speed than the driven roll 24. The clearance between the rolls is adjusted with the help of a presser means 25 of a wedge type, the presser means being actuated by'a drive 26.

The article is fed between the

rolls

23 and 24 and encompasse's them, while the tensioning of the article is effected by

reels

27 and 28.

The reel 27 that creates tension of the front end of the article is mounted from the side of the driven roll 24, and the reel 28 adapted to create tension of the back end of the article is disposed from the side of the driving roll 23. Such an arrangement of the

reels

27 and 28 makes the provision for the

rolls

23 and 24 to be encompassed by the article along a maximum possible arc.

There is a possibility of performing continuous rolling of sheet articles without encompassing the rolls of the mill as shown in FIG. 9. This mill comprises a plurality of consecutively arranged stands 29, 30 and 31 having, respectively, driving and driven

rolls

32 and 33 thatare rotated at different peripheral speeds and in opposite directions, but in such a manner as to make the ratio between their speeds equal to the reduction of the article r, the latter of which is passed between the

rolls

32 and 33 of each stand and tensioned from at least the front end thereof by a reel 34, the roll 32 being the driving one and the roll 33 the driven one, respectively.

In each preceding stand the driving roll 32 is kinematically associated with the driven roll 33 of the subsequent stand through a common reduction gear 35, with both rolls being rotated by the same drive (not shown).

The kinematic connection between the rolls is effected so, whereby the peripheral speed of the driving roll in the preceding stand is equal to the peripheral speed of the driven roll in the subsequent stand, and the ratio between the peripheral speeds of the rolls in each stand is equal to the reduction of the article in the respective stand, while the peripheral speed of the driving roll 32 in each stand accordingly increases in the direction of rolling by the value A of reduction in the given stand. In the mill provision may be made of a reel 36 for tensioning the back end of the article. Mills of this type have been proven to be more efficient.

The method of continuous rolling with the rolls being encompassed by the article tensioned from both ends can be effected on a mill of the type shown in FIG. 10, that comprises a plurality of pairs of driving and driven rolls 38 mounted in a housing 37, that are rotated in opposite directions with different peripheral speeds, but in such a manner, that the peripheral speed of the driving roll in each adjacent pair of rolls increase in the direction of rolling by the value of reduction of the article m therebetween. In the said mill wedge-type presser means 39 are provided that operate from drives 40 and are disposed from both sides of each roll 38. The presser means are adapted to adjust the distance between the axes of the rolls 38 so as to vary the effort with which the article m is reduced and to exclude uneven thickness of the article which consecutively encompasses all the rolls 38 in the course of being rolled. However, the article should not necessarily encompass the extreme rolls.

Industrial tests of the present invention have shown it to be quite promising and confirmed the advantages offered thereby and pointed out hereinabove.

ln particular, when carrying out the method of cold rolling of sheets with a thickness of 2 to 0.2 mm in rolls with a radius of 500 mm, the pressure of metal onto the rolls is diminished by as much as 3 to times and higher, which makes it possible to essentially increase the degree of reducing of the article per pass and to imporve-the efficiency of rolling.

What is claimed is:

1. A mill for rolling metal sheet articles with tensioning the front end of the article, comprising: rolling driving anddriven rolls; a drive means to rotate said rolls in opposite directions with different peripheral speeds so that the ratio between said peripheral speeds is equal to the reduction of the article being rolled, and the rate oftravel of the delivery end of the article is equal to the peripheral speed of the driving roll, said driving roll being rotated with a greater speed than the driven roll; at least one group of tension rolls adapted to tension the front end of the article during rolling, said group being kinematically connected to the driving roll so as to impart to the tension rolls a peripheral speed equal to the peripheral speed of said driving roll.

2. A mill for rolling metal sheet articles according to claim 1, wherein provision is made of an additional group of rolls for tensioning the back end of the article during rolling, said group being kinematically associated with the driven roll so, that the peripheral speed of said tension rolls is equal to the peripheral speed of the driven roll.

3. A mill for rolling metal sheet articles with tensioning the front and back ends thereof, said tensioning being effected by making the article encompass driven and the driving rolls of the mill, comprising: a drive adapted to rotate said rolls in opposite directions at different peripheral speeds so that the ratio between said speeds is equal to the drawing of the article rolled therebetween; a reel imparting tension to the article from the front end thereof, said reel being arranged from the side of the driven roll; and a second reel imparting tension to the article being rolled from the back end thereof, said second reel being disposed from the side of the driving roll.

4. A mill for rolling metal sheet articles with tensioning the front end of the article being rolled, comprising: a plurality of consecutively arranged stands with driving and driven rolls; a drive adapted to rotate said rolls in opposite directions with different peripheral speeds so that the ratio between said speeds be not less than the drawing of the article, and the rate of travel of the delivery end of the article is equal to the peripheral speed of the driving roll which is rotated with a greater speed, the driving roll of each preceding stand being kinematically associated with the driven roll of the subsequent stand; and means for tensioning the front end of the article during rolling.

5. A mill for rolling metal sheet articles with tensioning the front and back ends of the articles involved by making the articles consecutively encompass rolling rolls of the mill, comprising: a drive adapted to rotate said rolls in opposite directions with different peripheral speeds so that the ratio between said speeds in each adjacent pair of rolls is equal to the drawing of the article rolled therebetween; presser means adapted to adjustthe distance between the axes of rotation of said rolls, said presser means being disposed at both sides of each roll; and means adapted to tension the front and back ends of the article during rolling.

6. A method of rolling metal sheet articles by reducing between two driving and driven rolls, comprising; rotating the rolls in opposite directions so that the peripheral speed of one driving roll is greater than the peripheral speed of the other driven roll, said speed differential being in the same proportion as the thickness of the article before reduction is greater than the thickness thereof after reduction between said pair of rolls; adjusting the speed of the article leaving the reduction zone to equal the peripheral speed of the driving roll rotating at said greater speed, and applying a stretching effort to the end of the article leaving the rolls, the article encompassing the rolls in contact therewith in the course of the rolling and reduction process.

7. A method of rolling as claimed in claim 6, including applying a stretching load to the end of the article entering the rolls simultaneously with applying a stretching load to the end of the article leaving the rolls.

8. A method of rolling as claimed in claim 6, including generating friction in the reduction zone between the article being rolled and the driving roll rotating at said greater speed, said friction being greater than that between the article and the driven roll rotating at said lower speed.

9. A method of rolling metal sheet articles by reducing between driven rolls, wherein a pair of adjacent rolls are in direct contact with each other through a strip being rolled therebetween and are imparted rotary motion in opposite directions at different peripheral speeds, applying a tensile force to the outlet section of the article which is smaller than the force required to cause plastic stretching of the article, the article encompassing the roll rotating at a higher speed, rolling being effected at a ratio of the peripheral speeds of the rolls equal to that of the article thickness before and after reduction between said pair of rolls and at a speed of the outlet end of the article which is equal to the peripheral speed of the roll rotating at a higher speed, and applying a compressive force sufficient to cause plastic deformation of the article extending from the rolls.

prising a plurality of alternating driven and driving rolls, the article encompasses only the middle rolls of said plurality of rolls, and with the extreme rolls re-

Claims

1. A mill for rolling metal sheet articles with tensioning the front end of the article, comprising: rolling driving and driven rolls; a drive means to rotate said rolls in opposite directions with different peripheral speeds so that the ratio between said peripheral speeds is equal to the reduction of the article being rolled, and the rate of travel of the delivery end of the article is equal to the peripheral speed of the driving roll, said driving roll being rotated with a greater speed than the driven roll; at least one group of tension rolls adapted to tension the front end of the article during rolling, said group being kinematically connected to the driving roll so as to impart to the tension rolls a peripheral speed equal to the peripheral speed of said driving roll.

5. A mill for rolling metal sheet articles with tensioning the front and back ends of the articles involved by making the articles consecutively encompass rolling rolls of the mill, comprising: a drive adapted to rotate said rolls in opposite directions with different peripheral speeds so that the ratio between said speeds in each adjacent pair of rolls is equal to the drawing of the article rolled therebetween; presser means adapted to adjust the distance between the axes of rotation of said rolls, said presser means being disposed at both sides of each roll; and means adapted to tension the front and back ends of the article during rolling.

10. A method of rolling metal sheet articles as claimed in claim 9, wherein the tensile force smaller that the force required to cause plastic stretching of the article being generated by the article encompassing the roll rotating at a lower speed.

11. A method of rolling according to claim 9 comprising a plurality of alternating driven and driving rolls, the article encompasses only the middle rolls of said plurality of rolls, and with the extreme rolls remaining free.