US2071866A - Method of and apparatus for die rolling - Google Patents

Description

Feb. 23, 1937. T. N. SLOAN 2,071,856

METHOD OF AND APPARATUS FOR DIE ROLLING Filed May 4, 1954 5 Sheets-Sheet 1 Snventor Cittorneg Feb. 23, 1937. T. N. SLOAN 2,071,866

METHOD OF AND APPARATUS FOR DIE ROLLING Filed May 4, 1954 s Sheets-Sheet 2 Patented Feb. 23, 1937 UNITED STATES PATENT OFFICE IVIETHOD OF AND APPARATUS FOR DIE ROLLING Application May 4, 1934, Serial No. 723,819

9 Claims.

This invention relates broadly to the shaping and forming of metal and more particularly to an improved method of and apparatus for die rolling forging blanks and the like from ferrous metals, the blanks having accurately spaced portions of different cross sectional areas, without the formation of a fin or flash on the rolled article.

In my co-pending United States patent application, Serial No. 560,299, filed August 31, 1931, now patent No. 1,998,970, I have fully disclosed and claimed an improved flash-free die rolled forging blank and a method of and apparatus for manufacturing same. The leader bar is die rolled to form a plurality of connected, flash-free blanks with large and small sections accurately spaced apart the desired distances, and with reductions ranging up to about 40% in medium sized sections such as about 1 x2". With larger sections the reduction attainable is somewhat greater.

According to the present invention I have die rolled a leader bar into strings of connected flash-free, forging blanks, each blank having substantially straight or plane sides and irregular top and bottom surfaces, and having large and small sections accurately spaced apart desired distances, and with reductions of up to about 63% in medium sized sections without formation of flash. Where I-beam sections and the like are desired for a part of the length of the blank, I have, by the present invention, obtained reductions as great as 63% from the largest to the smallest section in the blank without flash and while obtaining the desired spacing between large and small sections.

Also, by the present invention, I have provided rolls in each of which the grooves are defined by a bottom wall and one side wall, after the fashion of a rabbeted recess or groove, and have thereby not only overcome any tendency of the blank to stick in the groove but have also obviated largely, if not completely, the use of end thrust bearings. Moreover, since the portions of the rolls which define the sides of the groove overlap each other and extend beyond the bottom of each groove, these portions constitute flanges which serve as side guides for the leader bar. These flanges project far enough ahead of the vertical center line of the rolls to prevent lateral flow of the leader bar metal which, in prior devices, could occur and often did occur with resultant formation of flash or damage to the rolls or both.

Other objects of my invention will appear from the following description of my improved method,

one form of rolls adapted to carry out my method, and several types of forging blanks which may be rolled by my method and apparatus, reference being had to the accompanying drawings, in which- Figure 1 is a side elevation of a pair of die rolls of my improved form.

Figure 2 is an end view of the roll shown in Figure 1.

Figure 3 is a vertical cross section taken on line 3-3 of Figure 1, showing a leader bar, partly in section, between the rolls.

,Figure 4 is a plan view of the pair of rolls shown in Figure 1, also illustrating the leader bar entering the rolls and the finished article leaving the rolls, and having a portion of the top roll cut away to better illustrate the engagement of the rolls with the stock.

Figure 5 is a perspective view of a portion of a string of automobile front axle forging blanks which have been rolled by the rolls of Figure 1.

Figure 6 is an enlarged vertical cross section taken on a plane joining the axes of the rolls and illustrating the portion of the roll pass adapted to form the portion of the blank indicated by line 6--6 of Figure'5.

Figure 7 is a view similar to Figure 6 but illustrating the roll pass which forms the portion of the blank indicated on line '|-l of Figure 5.

Figure 8 is a view similar to Figures 6 and 7 but illustrating the portion of the roll pass which forms the section of the blank indicated at line 8-8 in Figure 5.

Figures 9 and 10 are plan and side elevational views respectively of a form of crank shaft forging blank which is adapted to be rolled by my improved method and apparatus.

Figures 11, 12, 13, 14 and 15 are cross sectional views of the blank shown in Figures 9 and 10 taken on lines ll- -H, I2--l2, I3l3, i4l4 and I5-l5 respectively of Figure 10.

Figures 16 and 17 are plan and side elevational views of another form of crank shaft forging blank which may be rolled by my method and with my apparatus.

Figures 18, 19, 20 and 21 are cross sectional views taken on lines lB-IB, l9--I9, 20-20, and 2|2I of Figure 17.

Figure 22 is a cross sectional view illustrating a type of leader bar which may be advantageously used with my rolls.

Referring now to Figure 1, which illustrates rolls adapted to roll the blank of Figure 5, the upper roll A is carried by a suitable shaft l and the lower roll 13 is carried on its corresponding shaft 2. The roll shafts are, of course, mounted in bearings (not shown) in the usual manner and may be connected to any suitable driving means (also not shown) so that they will rotate together to maintain the proper angular relation between the different portions of the rolls. Five forming passes are provided between rolls A and B but it will be understood that this number may be increased or diminished without departing from the spirit of my invention. The upper roll A includes the matrix face portions 5, 6, I, 8 and 9, the outwardly extending flange portions III, II and i2, and the flange grooves I3, I 4 and I5. In like manner the lower roll B comprises the matrix faces l6, I1, I 8, I9 and 20, the outwardly extending flanges 2|, 22 and 23, and the flange grooves 24, 25 and 26.

The rolls are so disposed relative to each other that the flanges 23, 22 and 2| of roll B extend respectively into the flange grooves l5, l4 and I8 of roll A, while flanges IO, N and I2 of roll A extend respectively into flange grooves 26, 25 and 24 of roll B.

As will be more fully described later, the grooves in the rolls are made just wide enough to provide a very slight clearance for the flanges and it will be seen that with this roll arrangement, considering for example the left hand roll pass 21 (Figure l), the top surface and left hand side of the roll pass are defined by the matrix face 9 and flange l2 of roll A while the bottom surface and right hand side of the groove are defined by the matrix face l6 and the flange 2| of the roll 13. In corresponding manner each of the four other roll passes are formed with the top and one side surface in the top roll and the bottom and other side surface in the bottom roll. With this arrangement the side surfaces of the finished blanks'have little or no tendency to stick to either the top or bottom rolls because,. as the blanks leave the rolls, the side surfaces of the flanges M, II and I2 of the upper roll A are moving upwardly while the side surfaces of the flanges 2|, 22 and 23 of the lower roll B are moving downwardly.

The particular rolls illustrated in Figures 1, 2, 3, 4, 6, '7 and 8 are designed for rolling a string of connected but severable front axle forging blanks from a leader bar: Of course, by varying the contour of the matrix faces of the rolls and the flanges any desired article of this class may be formed. Other types of articles which can be rolled are the crank shaft forging blanks illustrated in Figures 9 to 21. Referring to Figure 5, which illustrates a portion of a string of rolled blanks, it will be noted that the dimension :2 of the string of blanks, that is, the horizontal dimension of the string of blanks, is constant throughout the blank while the other dimensions vary a great deal at different points of the blank. The end portions 28 of the blank have a cross sectional area preferably but slightly smaller than the cross section of the leader bar which is fed into the rolls. Spring boss portions 28 of the axle blanks are somewhat smaller in cross section than the portions 28. Intermediate the portions 28 and 29 are sections 30 of reduced cross sectionalarea while the relatively long r-beam section 3| which extends btwen the sections 28 is of greatly reduced cross sectional area as compared with sections 28 and 29.

Referring now to Figure 3, the matrix faces of the rolls are cut so that a single revolution of the rolls will form one complete axle blank. The portions a of the rolls are adapted to form the ends 28 of the axle blank. The portions 12 form the reduced sections 30, portions 0 of the rolls form the spring bosses 29 while the portions d of the rolls form the I-beam center section 3| of the axle.

Of course, if it is desired to roll a string of forging blanks for forming connecting rods, crank shafts or other die rolled articles the matrix faces of the rolls will be formed with the proper contours. In some instances it may be preferable to form the rolls so that a single revolution will form more than one article. In rolling the crank shaft blanks of Figures 9 to 21 the matrix face of the top roll will of course be different from the matrix face of the bottom roll as the blanks are not symmetrical about the longitudinal axis of the blank.

As the forming passes between the rolls are substantially completely closed, the clearance between the flanges of one roll and the grooves of the co-acting roll being very small, preferably about .003" in the illustrated rolls, the formation of flash is positively prevented. I have found that a small clearance such as noted above will not permit the metal to be forced into the space between the side of a flange and the side of its groove at the temperature commonly used for rolling articles of this kind from fe rous metals. However, if the leader bar is rolled a relatively high temperature greater clearance may be used without the formation of flash than can be used when the leader bars are rolled at a relatively low temperature, for the lower the temperature of the bar the greater is the tendency to formation of flash.

Another factor which enters into the formation of flash is the percentage of reduction in cross sectional area which is effected by the rolls. The greater the percentage of reduction the greater the pressure tending to force the metal into any clearance space between the rolls. Thus, where large reductions in areas are to be made it is be kept very small and my roll arrangement greatly facilitates the use of such small clearance.

In Figure 22 I have illustrated the general cross sectional shape of a leader bar which may be advantageously used with my improved die rolls. 'By properly relieving the diagonally opposite corners 40 and 4| of the leader bar the tendency toward the formation of flash or fln is reduced. The leader bar enters the rolls (for example the left hand pass of Figure 6) with the relieved comer 40 entering the upper right hand corner of the pass and the relieved corner 4| entering the lower left hand corner of the pass. Of course the exact shape of the leader bar may be varied for rolling different articles and Figure '22 is intended merely to illustrate how the opposite corners of the bar may be relieved to relieve the flash forming pressure at the clearance spaces between the rolls while still providing proper filling of the roll pass. In die rolling with the next pass to the right from the left hand pass of the rolls of Figure 6, the corners 42 and 43 of the leader bar would be relieved or chamfered and the corners 48 and 4| would be left full.

It has been observed that in the die rolling of forging blanks from a heated leader bar, the metal of the bar spreads laterally or horizontally when large vertical reductions of the bar are being made. If any vertical piling up occurs, it can be handled by the rolls without injury to the latter, but the metal which has spread laterally may contact with the edges of the matrix grooves and rolls and cause detrimental wear thereof. By making the outwardly projecting flanges of the rolls of a diameter sufficiently large to form guides for the sides of the leader bar for the space within which exists this tendency to lateral spread of the leader bar as it enters the matrix grooves, the difficulty incident to lateral spread is eliminated and the metal is confined laterally between substantially straight parallel planes.

In designing my rolls I proportion the flanges H), II, II, 2|, 22 and 23 so that lateral spread of the metal of the leader bar ahead of the rolls will be prevented and a guide restricting lateral flow will be provided for a distance at least as far ahead of the center line of the rolls as there exists any tendency for the metal to spread laterally. This feature of my invention is of particular importance as it prevents the formation of flash, excessive wear on the relatively sharp edges of the roll, greatly lengthens roll life, and permits greater reduction of the bar than would otherwise be possible.

I am aware that prior to my invention it has been proposed to utilize rolls having matrix surfaces and outwardly projecting flanges in the rolling of irregularly shaped articles. In United States Patent No. 55,270 to Fowler such an arrangement of rolls is illustrated. However, in Fowlers rolls and in others of this type with which I am familiar the end thrust on the rolls and roll shafts, which is necessarily great with such a roll arrangement, must be taken up by thrust bearings or the like. With my roll arrangement, however, I provide a plurality of roll passes and flanges whereby the side thrusts on one roll, which is set up by the passage of the metal through one pass, is opposed by several flanges. This arrangement is of particular importance in my construction in which I provide small clearances between the outwardly projecting flanges of the rolls and their corresponding grooves in the opposite rolls. Where end thrust is transmitted from one roll to another through such outwardly extending flanges the wear due to the friction is distributed over the several flanges and groove walls and this arrangement is. very effective in minimizing such wear and helpful in maintaining the clearance which I desire.

With my improved roll, illustrated in the drawings, the metal is completely supported and guided on the sides of the leader bar before the rolling pressure is applied to the top and bottom of the bar. This makes possible extremely great reductions in cross sectional area, it having been found in actual practice that reductions from the leader bar as great as 63% may be rolled satisfactorily and without the formation of fln while maintaining the requisite accuracy of spacing of the relatively large and small portions of the blanks. The greater the percentage of reduction in the roll pass the greater appears to be the tendency for the metal to back up ahead of the rolls and to spread laterally. Therefore, with my rolls, in making such large reductions the flanges of the rolls will be designed to form restraining side walls for a distance far enough ahead of the vertical center line of the rolls to prevent the leader bar from spreading laterally.

By correlating the clearance spaces between the roll flanges and grooves with the temperature of the metal being rolled and the percentage of reduction of cross sectional area effected by the rolls as above described I am able to die roll, without flash, forging blanks having extremely high reductions and having relatively large and small portions substantially accurate as to size and spacing. So far as I am aware such blanks have not been successfully die rolled prior to my invention. Restraining the metal from lateral flow ahead of the rolls for a distance as far as any tendency for such flow exists relieves the edges of the matrix grooves and flanges from the excessive wear which occurs with other types of rolls.

Although I have illustrated and described only one form of roll and several articles which can be formed .by my improved rolls and method, it will be understood that variations and modifications may be made in the type of roll used, both to accommodate the manufacture of different articles and 'to meet other conditions which may arise, and also my process may be modified without departing from the spirit of my invention. I do not, therefore, wish to be limited strictly to the specific embodiments of my invention herein illustrated and described but claim as my invention all forms thereof coming within the scope of the appended claims.

I claim:

1. In die rolling apparatus, a pair of rotatable die rolls, each roll having a matrix face extending in a direction generally parallel to the roll axis, a plurality of spaced flanges extending radially outwardly from said matrix face, a plurality of grooves extending radially inwardly from said matrix face, said grooves being disposed one between each adjacent pair of said flanges, the flanges of each roll extending into the grooves of the other roll and dividing the matrix faces whereby a plurality of roll passes are provided, each pass having its top and one side surface formed in one roll and its other surfaces in the other roll and having the engaging portions of the rolls disposed on opposite sides of the pitch line of the rolls.

2. In apparatus of the type described, a top roll having spaced matrix faces, a flange extending radially outwardly between said matrix faces, said roll having grooves on the opposite sides of said matrix faces from said flange, a bottom roll having spaced matrix faces, grooves between said bottom roll matrix faces and flanges extending radially outwardly from the sides of said bottom roll matrix faces opposite grooves in said top rool, and means for rotatably supporting said top and bottom rolls with their matrix faces opposite and the flanges of the top roll extending into the grooves of the bottom roll and the flanges of the bottom roll extending into the grooves of the top roll.

3. In apparatus of the type described, a top roll having spaced matrix faces, a flange extending radially outwardly between said matrix faces, said roll having grooves on the opposite sides of said matrix faces from said flange, a bottom roll having spaced matrix faces, a groove between said bottom roll matrix faces and flanges extending radially outwardly from the sides of said bottom roll matrix faces opposite said grooves in said top roll, and means for rotatably supporting said top and bottom rolls with their matrix faces opposite and the flange of the top roll extending into the groove of the bottom roll and the flanges of the bottom roll extending into the grooves of the top roll whereby a pair of die rolling passes will be formed, each pass having its top and one side surface defined by the top roll and its bottom and other side surface defined by the bottom roll.

4. The method of forming a string of substantially identical, irregularly shaped, forging blanks which includes the steps of passing a heated leader bar of substantially uniform cross-section axially between a pair of die rolls and, while so doing, reducing the vertical dimensions of the bar by varying amounts to form portions of large and small cross-sections with coincident tendency of the metal to spread laterally, and confining the sides of the bar throughout the distance wherein said tendency exists, thereby preventing such lateral spread.

5. The method of forming -a string of substantially identical, irregularly shaped, forging blanks which includes the steps of passing a heated metal leader bar of substantially uniform crosssection axially between a pair of die rolls, and,

while so doing, reducing the vertical dimensions of the bar by varying amounts to form portions of large and small cross-sections with coincident tendency of the metal to'spread laterally, and

confining the sides of the bar between substantially straight parallel planes throughout the distance wherein said tendency exists.

6. The method of forming an irregularly shaped forging blank which includes the steps of passing a heated metal bar of substantially uniform cross-section axially between a pair of die I rolls and, while doing so, reducing the vertical wardly from the matrix face of each roll, the groove of each roll being disposed opposite the flange of the other roll and the flange of each roll extending into the groove of the other roll whereby a roll pass is provided having its top and one side surface formed in one roll and its other surfaces in the other roll and having the engaging portions of the rolls dispoud on opposite sides of the pitch line of the rolls.

8. The method of forming a string of substantially identical, irregular shaped, forging blanks which includes the steps of passing a heated leader bar of substantially uniform cross-section and diagonally opposite rounded corners axially between a pair of die mils and, while so doing, reducing the vertical dimensions of the bar by varying amounts to form portions of large and small cross-sections with coincident tendency of the metal to spread laterally, and confining the by varying amounts up to about 63% to form por- 1 tions of large and small cross-sections with coincident tendency of the metal to spread laterally, and confining the sides of the bar throughout the distance wherein said tendency exists, thereby preventing such lateral spread and the formation of fins or flash at the initially rounded comers of the bar.

THOMAS N. SLOAN.

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