US3138982A - Strip rolling method - Google Patents

Description

June 30, 1964 c. L. SPORCK STRIP ROLLING METHOD 3 Sheets-Sheet 1 Filed June 29, 1962 H A k; P

{INVENTCZQ ATTORNEYJ June 30, 1964 c. L. SPORCK STRIP ROLLING METHOD 3 Sheets-Sheet 2 Filed June 29, 1962 z iiwdw a ATYWRJ EYS June 30, 1964 c. L. sPoRcK 3,138,982

STRIP ROLLING METHOD Filed June 29, 1962 3 Sheets-Sheet 3 42% of W4 & WWMi KM United States Patent 3,138,982 STRIP RQLLING METHOD Clans L. Sporclr, Cincinnati, Ohio, assignor to The Lodge 8: Shipley Cornpmy, Cincinnati, Ohio, at corporation of t'l'hio Filed June 29, 1962, Ser. No. 236,411 8 Claims. (Cl. till-60) This invention relates to metal working and in particular relates to methods for the removal of crown from strip stock. The methods herein, in certain respects, are improvements over the methods disclosed in my copending application Serial No. 121,653, filed July 3, 1961.

It is conventional to produce strip by rolling in a hot or cold mill with the finished product being sheared to size or wound into bands or coils. It is characteristic of rolling operations of the kind mentioned to produce crown on the rolled strip. Crown relates to uneven thickness distribution over the strip and the art has long sought practical and inexpensive ways to eliminate crown or to reduce its magnitude. This is particularly true under modern day conditions where very exacting tolerances are being specified for parts for use in aircraft, missiles and space vehicles.

As pointed out in my copending application, the art has removed crown principally by machining and grinding techniques. For the most part, crown on strip stock has been removed by an abrasive belt type grinding line set up as the final stand of the rolling mill or set up independently of the mill and arranged to handle bands or coils. Grinding lines of the ldnd mentioned have several disadvantages, for example, limitations on the maximum width of strip, the effects of heat generated by grinding, non-uniformity of thickness due to belt wear and waste of material. The latter is particularly undesirable because in many de-crowning operations by abrasive belts up to as much as about 10% of the total thickness is ground oil.

The principal object of the present invention is to provide improved methods of removing crown from strip stock at relatively high rates of speed, without waste of crown material and with the finished strip having a thickness tolerance accurate to a fraction of a thousandth substantially uniform over the strip.

The preferred manner of practicing the invention will be described below in connection with the following drawings wherein:

FIGURE 1 is a diagrammatic isomeric view of a strip being worked in accordance with the invention;

FIGURE 2 is a cross section of the strip of FIGURE 1 illustrating the configuration of the strip as it is being worked;

FIGURE 3 is a fragmentary plan view illustrating the locus of the reductions as taken on the strip;

FIGURES 4 and 5 are respectively elevational and plan views and illustrating how the strip of FIGURE 1 is worked while maintained in the form of a loop;

FIGURE 6 is a diagrammatic isomeric view of a strip being worked in accordance with the invention, the working being done in somewhat different manner than in FIG- URE 1;

FIGURE 7 is a cross section of the strip of FIGURE 4 illustrating the reduction in thickness and widening of the strip;

FIGURE 8 is a diagrammatic isometric view of a strip being worked in accordance with the invention, the manner of working being somewhat difierent than that shown in FIGURES l and 6; and

FIGURE 9 is a cross section of the strip of FIGURE 5 illustrating the reduction in thickness and widening of the strip.

In FIGURE 1, I have diagrammatically illustrated a mill for practicing the invention. This comprises a plurality of reducing rollers R which extend from a roller 1 along the dot and dash lines 2 to a roller 3. The reducing rollers are rotatable about horizontal axes. Below the several reducing rollers are a plurality of back-up rolls BR. For example, the first back-up roll 4 is just below the reducing roller 1 and the back-up roll 5 is just below the reducing roller 3 and the back-up rolls intermediate the rolls 4 and 5 are disposed below corresponding reducing rollers. The back-up rolls are rotatable about horizontal axes. On the far side of the mill are a plurality of guide rolls GR which are rotatable about vertical axis. The guide rolls are disposed along a straight line as between the guide roll 6 and the guide roll 7.

In FIGURE 1 the strip S may be coming from a band or coil or coming directly from a strip mill. In either event, the strip has a width Wand a thickness T which includes the crown (not shown). The leading edge 8 of the strip S is fed into the mill between the reducing roller 1 and back-up roll 4 and then the strip is moved through the mill in a direction indicated by the arrow 10 between the other reducing rollers and back-up rolls. When the leading edge 8 (or any other similar portion of the strip) has moved from the roller 1 through and beyond the roller 3, it has made a complete traverse through the mill. It will be understood that movement through the mill is effected by power driving the reducing and/ or the back-up rolls. Motion of the strip through the mill is continuous and uninterrupted.

The effect of moving the strip through the mill between the reducing and backup rolls is to reduce the thickness of the strip to a desired dimension and to expand the strip in a widthwise direction. This produces a finished strip FS having a thickness T (less than T and a Width W+E where E is the widthwise expansion of the strip. Sufiicient reduction is taken so that the finished strip FS is free of crown.

The reduction in thickness is dependent upon the spacing between the reducing rollers R and the corresponding back-up rolls BR. In the present arrangement, the space between each pair of reducing and back-up rolls is the same. The amount of widthwise expansion is a function of the amount of reduction.

During the traverse of the strip through the mill, the strip is maintained in lateral or widthwise position by virtue of the fact that the far edge 11 is held by the guide rolls GR and the central part by the reducing rollers R. The near edge 12 of the strip is free and this edge expands in a direction away from the reducing rollers.

The present invention utilizes the concept of incremental reduction as disclosed in my above-mentioned copending application. Thus, the working surfaces of the various reducing rollers R are relatively thin, being substantially smaller than the width of the strip. With a thin reducing roller R rolling into the strip, one very small increment after another is reduced or displaced progressively along a straight path. This kind of reduction is repeated successively along similar paths by virtue of simultaneously operating reducing rollers. In other words, as indicated in FIGURE 1 there are a plurality of reducing rollers which are spread across the face of the strip and each roller taking a very small bite or effecting very small incremental reductions along its path.

With a roller effecting a very small reduction, the force required for the roller to do its work is relatively small. Thus there are no reaction forces generated which could cause the roller to deform or how. Therefore, it is impossible for the finished strip F8 to have crown.

Inasmuch as the strip S has crown, some of the reducing rollers (particularly the central rollers) will do more work than the rollers toward the edges of the strip. With incremental reduction, however, the forces imposed on the central rollers are relatively small and roller spacing can be maintained while the rollers are free from deformation. Therefore, uniform thickness tolerance is provided on the finished strip FS.

With the above in mind then certain of the details for practicing the invention utilizing a mill of the kind shown in FIGURE 1 will be described below.

In FIGURE 1, the axis A represents the longitudinal axis of the strip S. The axis A is equi-distant from the parallel edges 11 and 12 of the strip. The strip in FIG- URE 1 is oriented horizontally and a vertical plane diagrammatically indicated at P and containing the axis A will also contain a thickness dimension (T and T The various back-up rolls BR extend at right angles to the axis A. The reducing rollers R are arranged so that as the strip is moved through the mill, the rollers displace the blank along paths which are parallel to each other and to the axis A and plane P. A vertical plane through any of these paths will be parallel to the plane P. As shown, the reducing rollers R are spaced from one another in a direction along the axis A and various simultaneous reductions of the reducing rollers take place at points which are axially spaced from one another. In FIGURE 3 the various simultaneous reductions being performed on the strip are represented by the dashes 13. It will be seen that the locus of the dashes extends between the opposite edges 11 and 12 and is acute to the longitudinal axis A.

The guide rolls GR are set up in conjunction with the end rollers 1 and 3 so that roller 1 works that portion of the blank which is parallel with and/ or co-extensive with the edge 12 and the reducing roller 3 works that portion of the blank which is parallel with or co-extensive with the edge 11. The various rollers intermediate the rollers 1 and 3 work corresponding portions of the strip.

As a strip is moved through the mill, the lead roller 1 reduces adjacent increments of the strip progressively along the path 14 which is co-extensive with edge 12. The small dots making up the path 14 can be thought of as the small adjacent increments which are progressively reduced by the roller. The reducing operation forms a groove 14a indicated in FIGURE 2. The other reducing rollers such as the rollers 15 and 16 respectively roll adjacent increments of the strip with the reducing being progressive along paths 17 and 18. The action of the rollers 15 and 16 form grooves 17a and 18a as shown in FIGURE 2. The grooves 17a and 18a have the effect of widening the original groove 14a. The width of the reduced increments (or of the grooves 14a, 17a, 18a, etc.) taken in a direction widthwise of the strip or normal to the plane P, is very small being substantially less than the Width W of the strip.

The rolling of the adjacent increments along each of the paths causes the strip to expand in the plane of the strip widthwise or normal to the plane P or the grooves as indicated at AB in FIGURE 2. For example, each increment of material previously in the area of the groove 14a can be thought of as being displaced into the area indicated by 14b; the material formerly in the area of the groove 1711 can he thought of as being displaced into the space 17b; and so on across the strip to the roller 3. Incidentally, with regard to the roller 3, the portion of the blank which is worked by this roller is in the nature of a narrow ridge running along the edge 12. The expanding portion of the strip as indicated by AE has the thickness dimension T which is the same as the spacing between the backup rolls and the reducing rollers. The final reduction is performed by the trailing roller 3 and with this reduction, the final expansion takes place and the strip is increased in width in an amount as indicated at E and has a thickness T The finished strip FS is free from crown.

It will be noted that the expansion of the worked portion 20 of the strip is gradual along the longitudinal axis A and this is due to the fact that the reductions by the 4 various rollers R are performed at points spaced from one another along the axis.

In FIGURE 1, I have shown the worked portion 20 and the unworked portion 21 (both within the mill) as being separated by a smooth ridge 22. This ridge is diagrammatic as it will be understood that the ridge is comprised of a series of off-set sections, the exact configuration of which depends upon the number of reducing rollers, their diameters and their respective axial spacing.

As indicated, the reducing rollers R are of the same diameter and are spaced in a widthwise direction so as to produce a smooth surface on the worked portion 20 of the strip. Usually the working or reducing surfaces of adjacent rollers are slightly overlapping in the widthwise direction. Under such transverse or widthwise spacing, the preferred spacing of the rollers in a direction along the axis A is such that the rotational axes of adjacent rollers are separated by a distance slightly greater than the roller diameter.

With reference to FIGURE 1, it will be observed that when the strip is moving through the mill, the various reducing rollers R rotate or move over the strip much in the fashion of a wheel running over the ground. Thus, the relative motion of the strip and reducing rollers is conducive to high speed operation. The actual speed of the strip through the mill is a function principally of the physical characteristics of the metal strip and the mechanical design of the instrumentalities holding the reducing rollers, the back-up rolls and the guide rolls. It will be understood, therefore, that the present methods are considerably faster than the de-crowning method shown in FIGURES 6, 7, 9 and 11 of my copending application.

In connection with FIGURE 1, it will be apparent that the strip is maintained in planar condition as it is being worked or moved through the mill. The methods herein contemplate that the strip, while it is being worked or run through the mill, be maintained generally in the form of a loop. That is to say, the strip enters the mill and leaves the mill in the same general area. This, of course, has the advantage of reducing the amount of floor space necessary for the mill and is conducive for setting up several mills in tandem. For example, in a situation Where it is required to remove the crown in a plurality of stages, a four stage mill can be set up where each stage takes care of one quarter of the material to be rolled down. A typical arrangement for maintaining the strip of FIGURE 1 in a generally loop form during working is shown in FIGURES 4 and 5.

In considering FIGURES 4 and 5, assume that the right hand end (FS) of the strip of FIGURE 1 has been moved around counterclockwise until it is adjacent the roller 1. The numbers and letters designating various parts of the strip in FIGURES 4 and 5 are the same as those used in FIGURE 1 to designate corresponding parts except that the numbers and letters of FIGURES 4 and 5 have prime marks.

A relatively large back-up roll 24 is provided with trunnions 25 by means of which the roll is mounted for rotation. The back-up roll 24 is equivalent to the backup rolls BR in FIGURE 1. Spaced around the surface of the roll 24 are a plurality of reducing rollers R. These are equivalent to the reducing rollers R in FIGURE 1. The reducing rollers extend from the lead roller 1' along the dot and dash lines 26, around the surface of the roll 24 to the trailing roller 3'. The strip S enters the mill underneath the upper positioning roll 27 and thence between the various reducing rollers R and the surface of the back-up roll 24. The finished strip FS' exits around the lower positioning roll 23. The strip is moved through the mill by power driving the back-up roll 24 and/ or the reducing rollers R. The edge 11 of the strip is held on the shoulder 29 of the roll 24. The shoulder 29 corresponds to the guide rolls GR in FIGURE 1.

In FIGURES 4 and 5, the strip is worked so that it is widened and de-crowned in accordance with the principles and in the same manner as described in connection with FIGURE 1.

In FIGURE 6, I have diagrammatically illustrated another mill for practicing the invention. In the mill of FIGURE 6, the strip is worked utilizing the same principles as described in connection with FIGURE 1 and therefore only a very brief description of the mill of FIGURE 6 is considered necessary.

Broadly speaking the strip 8-1 in FIGURE 6 is worked by a plurality of reducing rollers which extend respectively from opposite edges of the strip toward the center. Thus on the near side of the mill, the reducing rollers extend from a roller 30 along a dot and dash line 31 to a roller 32 which is located along the axis A-I of the strip. From the roller 32 the group extends along the dot and dash lines 33 to end roller 34. The rollers 30 and 34 are located opposite one another and the rollers adjacent the rollers 30 and 34 are also located opposite each other. Each such pair of rollers along the lines 31 and 33 are also at opposite positions on either side of the axis A-ll. The various reducing rollers have back-up rolls indicated at BR-l. The strip S-1 has width W and thickness T The lead rollers 30 and 34 are spaced apart so that as the leading edge 35 of the strip is moved into the rollers 30 and 34, they will operate respectively co-extensive with the strip edges 36 and 37. The rollers 30 and 34 move along paths indicated by the dotted lines 33 and 39 coextensive with the edges 36 and 37 and parallel with the axis A-l. The movement along the paths 33 and 39 forms grooves (FIG. 7) 38a and 39a. As the strip is moved through the mill, the pairs of rollers along the lines 31 and 33 respectively reduce increments along their respective paths and form grooves which have the effect of widening the grooves 38a and 39a. The trailing roller 32 rolls down the final piece of the strip which is co-extensive with the axis A-l. The unworked portion 40 of the strip assumes a generally triangular shape as the strip is going through the mill. The unworked portion 40 and the worked portion 41 are shown as separated by the ridge 42. Each pair of rollers takes the same incremental reduction and the strip equally expands on opposite sides of the axis A-l. The expanding edges are indicated by AE/ 2 in FIGURE 7, where E is the total expansion. The total expansion on each side is designated by E/2 in FIGURE 6. The finished strip FS-l is expanded to a width equal to W-l-E and has the desired thickness T this thickness being uniform over the strip area. The finished strip FS-l is free from crown.

As will be apparent from an inspection of FIGURE 6, the locus of the reductions of the various reducing rollers is comprised of the two lines (like the lines 31 and 33) which intersect at the roller 32 and respectively extend at an acute angle to the longitudinal axis of the strip.

The mill illustrated in FIGURE 6 can be arranged similarly as shown in FIGURES 4 and 5 so that the strip S1 is maintained in a loop form as it is being worked.

The mill of FIGURE 8 is an arrangement somewhat similar to the arrangement of FIGURE 6 in that the various reducing rollers R-2 are arranged in generally triangular form. In FIGURE 8 the strip is worked utilizing the same principles as described heretofore and only a 'very brief explanation of the working of the strip in FIGURE 8 is necessary. In this arrangement, however, the leading edge 43 of the strip S-Z first engages the lead roller 44 and is moved through the mill past the trailing rollers 45 and 46. The various other reducing rollers extend from the roller 44 along the dot and dash lines 50 and 51 respectively to the rollers 45 and 46.

The lead roller 44 effects its reductions along a path which is co-extensive with the axis A-2 and the other pairs of rollers arranged along the lines 50 and 51 efiect reductions along parallel paths. The rollers 45 and 46 eflect reductions along paths which are co-extensive with the opposite edges of the strip. As illustrated in FIG URE 8, the unworked portion 52 of the strip assumes a somewhat \l-shape. The ridge 53 represents the separating point between the unworked portion 52 and the worked portion 54.

With reference to FIGURE 9, it will be noted that the lead roller 44 forms a groove 44a and this groove is widened on both sides by the working of the various pairs of rollers along the lines 5th and 51. Each pair of rollers takes the same incremental reduction and the strip equally expands on opposite sides of the axis A-2. In FIGURE 9, the expansion of the strip on either edge is indicated by AE/ 2, where E is the total expansion. Note that the expanding portions each have thickness T This condition remains until the final reductions are taken by rollers 45 and 46. In FIGURE 8 the total expansion on each side is designated by E/ 2.

The number of pairs of rollers along the lines 50 and 51 including the rollers 45 and 46 and their respective widthwise spacing takes into account the widthwise expansion of the strip with thickness T up to the final reductions of rollers 45 and 46. The finished strip FS-Z has a width which is equal to W+E and a thickness T which is uniform over the strip area. The finished strip is free from crown.

In connection with the foregoing, it will be understood that various appropriately placed rolls can be provided for guiding the entry and exit of the strip to and from the mill and guiding the strip within the mill.

I claim: 1. A method of removing crown on metal strip stock comprising the steps of:

taking a piece of strip stock having crown; working the strip to reduce its thickness to a desired dimension by rolling adjacent increments of the strip to reduce the same to the desired thickness dimension, the reducing being progressive along a path extending along the longitudinal axis of the strip, the width of each said increment taken in a direction along the width dimension of the strip being substantially less than the width of the strip and the reduction along the path causing the stock to expand in a direction along the width dimension of the strip; and continuing with said working by performing second said step simpultaneously on a plurality of respectively adjacent areas of the strip, the path of each repeat step being parallel the first path and spaced from the first path in a direction along the width dimension of the strip and each of said reductions being performed at points spaced from one another along the longitudinal axis of the strip, the worked portion of the strip being free of crown. 2. The method of claim 1 wherein the portion of the strip being worked is maintained in planar form.

3. The method of claim 1 wherein the portion of the strip being worked is maintained in the form of a loop. 4. A method of removing crown on metal sheet stock comprising the steps of:

taking a piece of strip stock having crown; working the strip to reduce its thickness to a desired dimension by rolling adjacent increments of the strip to reduce the same to the desired thickness dimension, the reducing being progressive along a path extending along the longitudinal axis of the strip, the width of the increment taken in a direction along the width dimension of the strip being substantially less than the width of the strip and the reduction along the path causing the strip to expand in a direction along the width dimension of the strip; and

continuing with said working by performing said second step simultaneously on a plurality of respectively adjacent areas of the strip, and

performing said rolling so that the plurality of said reductions has a locus extending between opposite edges of the strip and acute to the longitudinal axis 8 7. The method of removing crown on metal strip stock comprising the steps of:

taking a piece of strip stock having crown; working the strip to reduce its thickness to a desired dimension by rolling adjacent increments of the strip to reduce the same to said desired thickness dimenof the strip, the worked portion of the strip being free of crown. 5. The method of removing crown on metal strip stock comprising the steps of:

taking a piece of strip stock having crown; working the strip to reduce its thickness to a desired dimension by rolling adjacent increments of the strip to reduce the same to said desired thickness dimension, the reducing being progressive along a path width dimension of the strip is substantially less than sion, the reducing being along a path which is co-extensive with the longitudinal axis of the strip; and

continuing with said working by simultaneously rolling which is co-extensive with one edge of the strip; and 10 adjacent increments of the strip to reduce the same continuing with said working by simultaneously rolling to said desired thickness dimension, the reducing beadjacent increments of the strip to reduce the same ing progressive along a pair of paths respectively to the said desired thickness dimension, the reducadjacent to and on opposite sides of first said path ing being progressive along a path which is adjacent and simultaneously rolling adjacent increments of the to and parallel first said path, simultaneously rollstrip to reduce the same to said desired thickness diing adjacent increments of the strip to reduce the mension, the reducing being progressive along a pair same to the desired thickness dimension, the reducof paths respectively adjacent second said paths and ing being progressive along a path adjacent second so on with such simultaneous rolling along a plurality said path and so on with such simultaneous rolling of respectively adjacent, parallel paths including a along a plurality of respectively adjacent, parallel pair of paths respectively co-extensive with the oppopaths including a path which is co-extensive with the site edges of the strip, and opposite edge of the strip, and performing said reductions so that the locus of the reperforming said rolling so that the locus of the reducductions is comprised of two lines intersecting one tions is comprised of a line which extends across the another interjacent the opposite edges of the strip face of the strip from one edge to the other and at and respectively extending from the intersection to an acute angle to the longitudinal axis of the strip and opposite edges of the strip at an acute angle to the so that the width of each said increment taken in a longitudinal axis of the strip and so that the width direction along the width dimension of the strip is of each increment taken in a direction along the substantially less than the width of the strip and the width dimension of the strip is substantially less than reductions along the paths respectively causing the the width of the strip and the reductions along the strip to expand widthwise, the worked portion of the paths respectively causing the strip to expand widthstrip being free of crown. wise, the worked portion of the strip beilig free of 6. The method of removing crown on metal strip stock crown. comprising the steps of: 8. A method of widening and providing precise thicktaking a piece of strip stock having crown; ness dimension in metal strip stock comprising the steps working the strip to reduce its thickness to a desired f;

dimension by rolling adjacent increments of the strip taking a piece of strip stock; t redu th sa e t ai d r d thickness dimenworking the strip by rolling adjacent increments of the sion, the reducing being progressive along each of a strip to reduce the same to the desired thickness di- P of Paths p y co-extehsive With pp mension, the reducing being progressive along a path edges of the strip; and extending along the longitudinal axis of the strip, the whtinuing With shlid working y simultaneously Toning width of each said increment taken in a direction adjacent increments of the strip to reduce the same to along th id h di i f h Strip being b. d desired thickness dimension, the reducing stantially less than the width of the strip and the 8 Progressive along a P 0f Paths respsctiyely reduction along the path causing stock to expand in iacsnt first said Paths and simultaneously rolling a direction along the width dimension of the strip; jacent increments of the strip to reduce the same to d the desired thickness dimension, the reducing being continuing with said working by performing second said along Paths respectively adiacsnt second said Paths step simultaneously on a plurality of respectively and 80 On With Such Simultaneous rolling along a adjacent areas of the strip, the path of each repeat plurality of respectively adjacent, Parallel Paths step being parallel the first path and spaced from the eluding a p which is coextensive with the g first path in a direction along the Width dimension tudinal aXi 0f the s ip, a of the strip and each of said reductions being perperforming said reductions so that the locus of the ref d t points spaced from one another along the ductiohs is Comprissd two lines intersecting one longitudinal axis of the strip and thereby cause the another ihtel'iacent the pp edges of the strip worked portion of the sheet to have the desired width and respectively extending from the intersection to d thi kne dimension. opposite edges of the strip at an acute angle to the longitudinal axis of the strip and so that the width References Cited in the file of this patent of each increment taken in a direction along the UNITED STATES PATENTS the width of the strip and the reductions a ong t 3322 25 g" paths respectively causing the stnp to expand wl h- 2:367:226 Lonsdale M Jan 16, 1945 wise, the worked portion of the strip being free of crown.

Claims (1)

1. A MATHOD OF REMOVING CROWN ON METAL STRIP STOCK COMPRISING THE STEPS OF: TAKING A PIECE OF STRIP STOCK HAVING CROWN; WORKING THE STRIP TO REDUCE ITS THICKNESS TO A DESIRED DIMENSION BY ROLLING ADJACENT INCREMENTS OF THE STRIP TO REDUCE THE SAME TO THE DESIRED THICKNESS DIMENSION, THE REDUCING BEING PROGRESSIVE ALONG A PATH EXTENDING ALONG THE LONGITUDINAL AXIS OF THE STRIP, THE WIDTH OF EACH SAID INCREMENT TAKEN IN A DIRECTION ALONG THE WIDTH DIMENSION OF THE STRIP BEING SUIBSTANTIALLY LESS THAN THE WIDTH OF THE STRIP AND THE REDUCTION ALONG THE PATH CAUSING THE STOCK TO EXPAND IN A DIRECTION ALONG THE WIDTH DIMENSION OF THE STRIP; AND

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