US2038908A - Rolling of rectangular bars - Google Patents

Description

2% 3935- scHoLL I I 2,9399

ROLLING OF RECTANGULAR BARS Filed Sept. 29, 1933 s Sheets-Sheet 1 zmwm 7 8, E6. .1. SCHOLL ROLLING OF RECTANGULAR BARS Fild Sept. 29, 1933 s Sheets-Sheet 2 I INVENTOR Patented Apr. 28, 1936 UNITED STATES PATENT OFFICE 11 Claims.

This invention relates to the rolling of rectangular bars and provides a method and apparatus whereby such bars may be rolled at ;low cost with great accuracy and with a resulting superior product. The word bar is used herein as one of general definition and not of limitation. Specifically it is not intended by the use of such term to limit its application to those bodies commercially classified in the trade as bars.

In the rolling of rectangular bodies by methods heretofore in use, the practice has been to roll in diamond .passes so proportioned that the long dimension of a diamond entering a pass is re- .duced to the shorter dimension of the issuing diamond, there being sufiicient width in the pass to permit of the entering bar spreading as .it is reduced on the long dimension. Some rectangular shapes have also been rolled by a slabbing operation, but in each case the general rule has been that the metal can be reduced in only one dimension ata time. It has beenconsidered impossible to reducein both dimensions, that is to :say, both vertically and horizontally as the piece is positioned in the rolls; first, because it was '25 deemed impossible to enter the bar ,in the rolls,

and second, because of the danger of overfills.

I have found that thesedifficulties can be overcome :and a highly satisfactory product maybe obtained by a material departure fromaccepted rules of roll design for this class of product. .Briefly stated, I provide'for forming a bar of generally rectangular shape but having diagonally opposite corners blunted, feeding such bar between a pair of rolls having grooves therein which form av pass of generally rectangular section smaller in both cross sectional directions than the bar and with its several main faces inclined :tothe roll axes. The bar is :fed to this pass with .its main .faces inclined .to the horizontal. The blunt corners permit of the bar being-fed between the shoulders of the roll grooves which would he impossibleif the bar were a full rectangle incross section. The blunt corners also permit of the .bar being reduced in both directions in the pass without overfilling. To obtain the full .benefits of my invention I prefer that thereshall be asuccession of passes of the character just describedand that these several passes, with the exception of the finishing pass, shall act not only to reduce the bar in both directions but .alsoto blunt diagonally opposite corners thereof so that it will besuitable forentering the succeeding pass.

'Bars'made according to my invention are accurate as to size and shape and exhibitsuperior physical-qualities. A uniform macro-structure is obtained, micro-etchings indicate a more uniform grain size throughout, and torsion and upsetting tests show that bars rolled according to my invention are less susceptible to cracking under severe working. The several tests indicate that the metal is more uniformly worked throughout and a more homogeneous bar is obtained.

In the accompanying drawings illustrating a present preferred embodiment of the invention,

Figure 1 is a front elevation of a pair of rolls showing the manner of forming the grooves therein;

Figures 2 to '7 inclusive are views showing the successive passes and the reductions effected in each pass;

Figure 815a Perspective of the billet employed; and

Figure ,9 is a perspective view.

Figure 1 shows the general configuration of the rolls. It illustrates to reduced scale two passes each corresponding to the pass of Figure 5 here- 'inaifter described in more detail. It will be ,understood, of course, that the passes might be placedin a single pair of rolls although it is preferred to use a continuous mill, successive passes J Figurelshows a lower roll ;.2 and an upperroll 3 having grooves 4 and 5 cut therein .to formthe roll pass. The shoulders of the grooves are indicated at 6 and 1. As above indicated, it is necessary that the entering bar be of such size that it can be entered between the shoulders in an amount suilicient to permit of the rolls'gripping the leading end so as to draw it into the pass.

Considerable pressure tending to displace the rolls axially is developed during the rolling and this -is resisted. by collars 88 and 9--'9 bearing, respectively, on one another at [0 and H.

Referring now to Figure 8, there ;is shown a billet of octagonal form, or it may be, considered as a rectangle, having principal sides l2 with blunted corners l3 connected to the principal sides by radii M. In the first pass the billet indicated as B 'in Figure 2 is fed to a pass of the shape illustrated in Figure 2. This pass is generally rectangular in form, the principal :faces I5 and I6 being formed in the lower roll and the principal faces I! and I8 being formed in the upper roll. The billet B is fed to the pass through guides which so orient it that its principal 'faces [2 lie substantially parallel with the principal vfaces of the pass opening, as indicated in Figure 2. It will be noted from Figure 2 that the billet must be reduced in both directions in the pass. This is accomplished by having the sev eral faces l5, l6, l1 and I8 inclined to the axes of the rolls. I have indicated at AA on Figure 2 a line parallel to such axes.

The reduction of the billet causes elongation and also causes a certain amount of spreading in the pass. If this spreading were too great it would cause overfills by reason of the metal flowing into the spaces [9 at the parting line of the rolls. The blunted corners l3 of the billet allow sufficient room for spreading to insure that there will be no overfilling.

It has been stated that the grooves forming the roll passes have shoulders and that it is necessary for the entering bar to be of such size and shape that it can enter between the shoulders. The blunted corners also make this possible.

The pass of Figure 2 is provided with blunted corners 20 and 21 between the faces l5 and I6 and the faces I! and [8 respectively. The rolling of the billet through this pass results in the formation' of a bar whose shape I have indicated at Bl in dotted lines (Figure 3). The bar BI 'is fed to the pass of Figure 3 with its blunted corners adjacent the spaces 22 at the parting line of the rolls. The pass of Figure 3 is generally like the pass of Figure 2 except that it is smaller in size. It is generally in the form of a rectangle having the principal faces 23 and 24 in the bottom roll connected by a fillet 25 at the corners,

and the principal faces 26 and 21 in the upper roll connected by a fillet 28. The fillets 25 and 28 serve to drastically blunt the corners of the bar Bl to prepare it for the next pass. The principal faces of the pass in Figure 3 are inclined to the roll axis and the blunt corners of the bar Bl are so located during the rolling that they permit of entering the bar between the shoulders and also prevent overfilling. I have indicated by dimension lines R on Figure 3 the reduction on each face of the bar BI, and have indicated by dimension lines S the maximum permissible spreading of the bar Bl in the pass if overfilling is to be avoided. I have found that the distance S must be at least half the distance R if overfilling is to be avoided. This rule may be safely followed in designing passes for the rolling of It will be noted that the several passes follow the principles set forth above as to configuration, inclination of the main faces to the roll axes and provision of blunted corners which allow entering and spreading in the pass.

While I have illustrated and described the present preferred form of my invention, it is to be understood that the invention may be otherwise embodied and practiced within the scope of a pair of rolls, the pass being of generally rectangular section, smaller in both cross-sectional directions normal to its principal faces than the first pass but having a diagonal longer than the blunted diagonal of the first pass, and with its several principal faces inclined to the roll axes, the first pass being effective for blunting the corners of the bar sufficiently to permit of entering the bar between the shoulders of the roll grooves forming the second pass.

2. In combination, a plurality of roll passes each of generally rectangular cross section and diminishing progressively in size so that each roll pass is smaller in both cross-sectional directions than its predecessor, the principal faces of the several rectangular passes being inclined to the axes of the rolls in which they are formed, the several passes being also so formed as to blunt diagonally opposite corners of a bar fed therethrough in an amount sufficient to permit of entering such bar between the shoulders of the grooves forming the succeeding pass, the blunting being in such amount that when a piece formed in one pass is entered in the succeeding pass the distance from such piece to the junction of the parting line of the rolls with the pass opening is at least half the reduction per side of the piece.

3. A rolling mill comprising successive roll passes each of generally rectangular cross sectional shape with two opposite corners blunted, the cross sectional areas of the successive passes becoming smaller toward the delivery end of the mill, at least certain of the passes each having a diagonal longer than the diagonal between the blunted corners of the immediately preceding pass.

4. A rolling mill comprising successive roll passes each of generally polygonal cross sectional shape with at least two non-adjacent corners blunted, the cross sectional areas of the successive passes becoming smaller toward the delivery end of the mill, at least certain of the passes each having a diagonal longer than a diagonal through a blunted corner or" the immediately preceding pass.

5. A rolling mill comprising successive roll passes each of generally polygonal cross sectional shape with at least one corner blunted, the cross sectiOnal areas of the successive passes becoming smaller toward the delivery end of the mill, at least certain of the passes each having a diagonal longer than a diagonal through said blunted corner of the immediately preceding pass.

6. A method of rolling products of generally rectangular cross-section, comprising reducing a blank in a roll pass to generally rectangular cross-section with a face of the blank inclined to the roll axes and with opposite corners blunted and then reducing the blank in another roll pass the roll axes of which extend at substantially the same angle to the horizontal as the roll axes of the first mentioned pass and increasing in the second mentioned pass the transverse dimension of the blank through the blunted comers formed in the first mentioned pass.

'7. A method of rolling products of generally of the first mentioned pass and increasing in the second mentioned pass the transverse dimension of the blank through the blunted corners formed in the first mentioned pass.

8. A method of rolling products of generally rectangular cross-section, comprising reducing a blank in a roll pass to generally rectangular cross-section with a face of the blank inclined at an angle less than 45 to the roll axes and with opposite corners blunted and then reducing the blank in another roll pass the roll axes of which extend at substantially the same angle to the horizontal as the roll axes of the first mentioned pass and increasing in the second mentioned pass the transverse dimension of the blank through the blunted corners formed in the first mentioned pass.

9. A method of rolling products of generally rectangular cross-section, comprising reducing a blank in a roll pass to generally rectangular cross-section with a face of the blank inclined to the roll axes and with opposite corners blunted the blunting of such corners being in such amount that the distance from the blank to the junction of the parting line of the rolls with the pass opening is at least half the reduction per side of the blank, and then reducing the blank in another roll pass the roll axes of which extend at substantially the same angle to the horizontal as the roll axes of the first mentioned pass and increasing in the second mentioned pass the transverse dimension of the blank through the blunted corners formed in the first mentioned pass.

10. A method of rolling products of generally rectangular cross-section, comprising reducing a blank in a roll pass to generally rectangular cross-section with a face of the blank inclined to the roll axes and with opposite corners blunted and then reducing the blank in both directions parallel to its principal faces in another roll pass the roll axes of which extend at substantially the same angle to the horizontal as the roll axes of the first mentioned pass and with the opposite corners intermediate those blunted in the first mentioned pass blunted and increasing in the second mentioned pass the transverse dimension of the blank through the blunted corners formed in the first mentioned pass, the blunting of the corners being in such amount that the distance from the blank to the junction of the parting line of the rolls with the pass opening is at least half the reduction per side of the blank.

11. A roll stand comprising rolls forming a pass the principal faces of which extend substantially at right angles to one another, said pass having adjacent principal faces both inclined at an acute angle to the roll axes, said inclination being unequal as to the respective principal faces, said pass also having at least two non-adjacent corners blunted.

JOSEPH SCHOLL.

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