US1998970A - Die rolled article and die rolling method - Google Patents

Description

April 23, 1935. T. N. SLOAN 1,998,970

v DIE ROLLED ARTICLE AND DIE ROLLING METHOD Filed Aug. 51, 1931 2 Sheets-Sheet 1 ,1 l N- M! T II THOMAS M SZOA/V T. N. SLOAN 1,998,970 DIE-ROLLED ARTICLE AND DIE ROLLING METHOD I A ril 23, 192.5.

Filed Aug. -31, 1931 2 Sheets-Sheet 2 I gwvenioc rho/ms m 51 0A N abhor/wag 5 Patented A a... 23,1935

PATENT OFFICE DIE ROLLED ARTICLE AND DIE ROLLING METHOD Thomas N. Sloan, Buffalo, N. Y., assignor to The Republic Steel Corp., Youngstown, Ohio, a corporation of New Jersey Application August 31, 1931, Serial No. 560,299

19 Claims.

' This invention relates broadly to the are r die rolling and more particularly to die rolled, connected, flash-free forging blanks and analogous articles having complex shapes, and to a and cheapen the cost of production thereof by eliminating certain steps and attendant operations heretofore considered essential in their manufacture. Y

Prior to this invention automobile front axles, cam-shafts and like articles having large and small portions have been produced commercially by forging a rolled bar of uniform cross section into a blank suitable for the forging die, in which the blank was then forged into an article of the desired shape. This method, while slow and expensive, had been the most commercially practical method known in the art, although various efforts have been made to produce forging blanks for such articles by die rolling.

The earlier efforts to die roll such articles were directed toward the adaptation of the methods,

used in rolling hardware articles such as iron straps, tie rods, fish plates, etc. to the rolling of forging blanks, but in no instances, as far as I know, have such ventures met with any commercial success and they have beenabandoned. Their failure may be attributed to the inability to control longitudinal dimensions between portions of the blank and the relatively-great change in cross section or reduction. This inability was manifest in skidding or relative slippage between the bar and rolls. Following these attempts, efforts were made to adapt the flash principle of length control, such as is used in the die rolling of circular drive shafts for automobiles to the production of front axle forging blanks, but the flash produced as an important part of that process had to be trimmed and/ or ground off, entailing considerable expense and a separate operation which slowed down production, and moreover, the flash or flash line was objectionable because it was often the starting point in the development of cracks during the subsequent diflicult or severe forging operations. To avoid flash, a two pass die rolling method was tried in which the metal was permitted to spread freely laterally in the first pass and was then rolled back into shape by the second pass so that the blank was flat and of uniform dimension between two opposite surfaces.

The two-pass method had several serious inherent disadvantages which have prevented its adoption on a commercial scale, among which disadvantages may be noted the following:

First, the heated leader bar cooled unequally during rolling and the large and small portions formed by the first roll pass were consequently often altered materially in the second pass, particularly as regards the length of the smaller sections or the spacing of the larger portions along the bar, and thus the center to center dimensions were not maintained within the limits required by the final forging dies. While the variable lengthening of parts of the bar might have been compensated for, in part, by more expensive diesink-'- ing operations, or cured by cutting where they occurred at the end of the blank, such lengthening as occurred intermediate the ends of the blank could not be-so cured and a blank which does not meet the forging die requirements has to be dis- 1 carded as scrap. I

Second, the variations in cross section along a rolled leader bar gave the string of blanks a tendency to twist, tilt or camber after leaving the first pass, and this tendency was exaggerated in the second pass where the twisting or leaning of the tall narrow part of the blank was emphasized and the symmetry thereof with respect to a central plane at right angles to the rolls was altered during flattening. Such distorted blanks, whenstruck in the forging dies tended to overfill some parts of the die and underfill'other parts, resulting in defective articles.

Briefly summarized, neither the flash method nor the two pass method has been commercially successful for all purposes because of the forging and possibly other inherent disadvantages.

vThe products typical of my invention may be briefly described as being a string of connected, substantially identical, die rolled, flash free forging blanks having substantially no lean, twist or tilt and having generally rectangular portions of different heights and Widths spaced apart by predetermined distances and having predetermined cross sectional dimensions, all within close tolerance limits, that is, within the tolerances of dies used in the subsequent forging operation. By my improved method and apparatus, I am enabled to produce such articles on a commercial scale and in a single roll pass.

Briefly stated my method may be carried out by the following steps; passing directly from the mill and between a single set of die rolls, a rectangular metal leader bar having its greater dimension disposed at right angles to the surfaces of the rolls, this height or vertical dimension being slightly greater than the greatest depths of the grooves in the rolls and the width dimension being slightly less than the width of the grooves; slightly reducing the height of certain portions of the bar, and greatly reducing the height of other portions of the bar with simultaneous control of lateral spread, while preventing flash and controlling the locations of the larger and smaller portions along the bar within the close tolerances required by forging dies and in a manner to form similar connected but severable blanks.

One form of apparatus embodying my invention consists of two cylindrical members, such as a set of die rolls, each mounted to rotate about its longitudinal center line and each provided with complementary matrix "grooves shaped and dimensioned so that the rolls will grip the bar in such manner as to prevent relative slippage and restrain the lateral flow of the metal and direct it longitudinally toward the unrolled part of the bar. The shallower parts of the said grooves are correlated, as to width and shape, with the diameter of the rolls or cylindrical members so as to influence or control the lateral spread of the bar; and as to length, with the rotational or peripheral speed of the rolls so that elongation of the bar on the discharge side of the rolls will be substantially prevented. Thus I have provided a method of and apparatus for die rolling which enables me to produce in one operation a relatively great deformation or change in crosssectional contour of a leader bar with accurate center-to-center lengths between the deformed portions and without the use of flash as an aid in length control, and with sections which may subsequently be forged into channel or beam sections with approximately equal filling of all parts of the forging die.

I have chosen to disclose my invention by setting forth in detail herein, as one embodiment of it, the method and apparatus I have used to form a heated leader bar into a string of forging blanks for front axles for an automobile.

In the drawings accompanying and forming a part of this specification Figure 1 is a view in section and side elevation of apparatus embodying the present invention for die rolling a front axle forging blank, certain parts having been omitted.

Figure 2 is an end elevation taken on line 2- of Fig. 1.

Figure Bis an enlarged view of one of the rolls of Figure 1.

Figures 4 and 4a are respectively views in top plan and side elevation of a forging blank as produced by the die roll pass of Figure 1.

Figures 5a to 5d, inclusive, show cross sectional views taken on lines A, B, C and D of Figure 4a; and

Figure 6 is a perspective view showing a fragment of a leader bar die rolled by this invention into a string of connected front axle forging blanks.

In Figures 1, 2 and 3, which show one form of die rolling device embodying my invention, i and 2 designate cylindrical rings keyed to mandrels 3 and 4, respectively, which are suitably mounted in bearings (not shown) to rotate about their centerlines and which are driven by any suitable means (also not shown). Each ring and its mandrel may be considered as a roll or member unit, but made in two parts for convenience and cheapness in manufacture, upkeep and repair.

The rings l and 2 are mounted with their surfaces close together, a space of about A" therebetween being suitable for a front axle forging blank and suificient for adjustments to compensate for differences in temperatures of the heated leader bars.

Complementary grooves 5 and 6 in the faces of the rings l and 2 extend circumferentially of the rings. These grooves are made up of'deep, narrow parts and shallower, wider parts and are long enough to form one complete front axle forging blank from a leader bar for each revolution of the rings.

The deep, narrow parts I and 8 of the grooves 5 and 6 are of slightly less depth than'the vertical height of the leader bar so that the latter is but slightly deformed therein, and are slightly wider than the bar so thatno flash is initially formed. Since there is very little reduction or deformation at these points, it will be seen that there is little danger of inaccurate lengths due to roll slippage or skidding and for extrusion of metal into the formed bar during this phase of the rolling operation. The shallower, wider parts 9 and ID of grooves 5 and 6 are of considerably less depth than the. parts 1 and 8 and are much wider. The difference in depth between parts i and 8 and the parts 9 and I0 is the amount of draw or reduction in the smaller sections of the blank and it is this reduction that has heretofore rendered accurate and uniform dimensioning of this type of articles a diflicult problem.

In constructing the rolls I and 2 in accordance with my invention, several factors are taken into consideration and correlated, including (a) the dimensions and shape of the-grooves, (b) the relative location of the deep and shallow parts of the grooves, (c) the diameter of the rolls, ((1) the rotational or peripheralspeed of the rolls, and (e) the size and shape of the leader bar. A

rolling temperature of around 1800 F. is suitable, although this may vary over a relatively wide range without serious effects.

To. illustrate a course of procedure that may ,be followed in practicing my invention, I preferably first lay out a pattern blank dimensioned to produce a forging in accordance with given the standard usually being accepted as 1/64" for each inch of blank at a temperature of 1 800 F.

After thepattern blank has thus been suitably laid out, a forging blank is developed from it by taking into account any bends therein or other variations from a straight line, for the forging blank is rolled straight and later bent before being placed in the forging dies. The rolled blank must be capable of such bending and the like. Then matrix grooves in the rolls are developed to form the forging blank. In developing the grooves, I first locate the deep parts relative to each other and make them large enough to give the metal necessary to form portions on the blank which will forge into the large'parts of the axle. Then the smaller parts of the groove are formed to give the required amount of draw or reduction of the leader bar for the smaller parts of the blank. The Walls which define the matrix grooves have an important bearing on the results to be obtained. The side Walls arepreferably given a taper or clearance near the bottom of the grooves as at I2 (Fig. 3) and from these points to the surface of the rolls they are preferably substantially straight sided and parallel. The width of the groove at the parts 9 and II! or in the region where the greatest deformation of the bar takes place is such that the metal will spread against the walls of the groove and fill the grooves but not overfill them to the extent that flash will be formed on the sides of the'blank. A generally rectangular cross-sectional shape with substantially parallel sides and oval-shaped top and bottom as shown in Figs. 5A to 5D, inclusive, facilitates such filling and flash prevention. I have found that the lateral spread or flow of the metal during the rolling operation may be reduced and controlled by making the bottom surfaces of the matrix grooves in the die rolls rounded to form an article having rounded top and bottom surfaces as shown in Figures,5A, 5B, 5C and 5D. By thus controlling and restricting the lateral flow of the metal the matrix grooves in the rolls will be just filled by the metal but not overfilled to cause extrusion of the metal into the space between the rolls and the forming of a fin or flash even when the leader bar is subject results obtained with grooves having rounded b'ottom surfaces are due to reasons other than those given above. In conjunction with the foregoing, there is subtracted from the depth of the groove the estimated amount of roll spring, so that the metal is firmly gripped in the matrix groove when the deformation action takes place. The substantially parallelside walls of the groove greatly restrict the free flow of metal and cause it to fill the groove, any excess metal being given a tendency to flow lengthwise toward the unrolled part of the bar, the peripheral speed of the rolls influencing this latter action.

Figure 3 taken in conjunction with Figures 4, 4a and "5 illustrate a suitable matrix groove in one of the rolls. Considering the blank in Figures 4 and 4:1 as a forging blank, the actual dimensions of the groove may be arrived at by adding a shrinkage allowance of about 1/64" per inch of the cold blank to the thickness of the blank, (that is, to the sides presented to the observer in Figure 4a). From this sum is subtracted the estimated amount of roll spring and roll set. This gives the correct groove depth, one-half of which is preferably in each roll. The width of the groove is substantially the same as that of the forging blank plus shrinkage, (this width being from side to side of the blank presented to the observer in Fig. 4). The relative spacing of the deforming portions of the matrix groove and the substantially undeforming portions and the amount of draw therebetween is substantially as indicated by the lines of projection 5A, 5B, 5C and 5D in Figs. 4 and 4a.

Preferably the diameter of the rolls is such that but one blank can be formed by a single rotation of the rolls, as experience has demonstrated that such diameter co-ordinates satisfactorily with the width of the shallow portions of the groove to produce the proper lateral spread of the metal. It will be understood, however, that where the articles are so short as to make this impractical, more than one blank can be formed by a single rotation of the rolls.

As the speed of rotation of the rolls influences the, longitudinal and lateral flow of the metal, this speed' should be regulated with respect to the diameter of the rolls and the spacing and dimensions of the matrix portions. However, this speed may vary over a relatively wide range, in which longitudinal flow of the metal into the already formed part of the blank has little or no tendency to take place. Suitable speeds are from about 100 lineal feet per minute upwardly. As the speed increases the lateral flow is decreased.

A satisfactory type of leader bar is one having a cross-section approximately the shape of the deeper parts of the matrix groove but slightly greater in height, andslightly less in width, so that the bar will be reduced slightly thereby when rolled. In Figure 1, the leader bar is designated at I3. This figure shows how a string of flash free blanks is rolled direct from the leader bar in one'operation.

Figure 6 shows the string of connected blanks after the rolling operation. The parts la8a are formed by the portions 1 and 8 of the matrix grooves and subsequently forged into the spring pads of the axle. The parts Sit-Illa, are formed by the portions 9 and ill of the grooves and are subsequently forged into the sections of the axle which lie between the steering spindle swivel and the spring pads. The part 5a-6a is formed by the portions 5 and 6 of the matrix grooves, and this portion of the string is severed at an intermediate point and each adjacent end formed into a steering spindle swivel. The central channel or I-beam section 0' of the axle is formed by the portions 0 of the matrix grooves.

In practice, I pass a heated leader bar of the proper size and shape directly from the mill on.

edge between driven and matched rolls and 2 in grooves Band 6. The large parts I and 8 of the grooves reduce the height of the leader bar slightly without material lateral spread and without formation of flash, while the parts 9 and- ID draw the bar or reduce its height to any desiredamount up to, forexample, about 40% or more, with coincident lateral spread but still without flash. As this radical deformation of the bar begins, there would be, under the old unsuccessful attempts at rolling. a tendency toward slippage or skidding of the rolls on thebar with consequent fatal results, unless flash was used to prevent such action. With my meth- 0d and apparatus, however, the bar holds to the rolls due to the correlation of the several factors above mentioned and deformation takes place in accurate spaced relation while simultaneously the metal is directed longitudinally and laterally, the longitudinal flow being controlled so as to merge into the bar during its formation while not altering the predetermined contour of the bar or length of the formed parts of the bar; and the lateral flow being restricted and controlled so astions relatively to prior methods of die rolling,

due to the fact that the side edges of the matrix grooves are not constantly biting on the metal and being broken down thereby, actual experience having shown a reduction of more than 80% in roll costs. The blanks almost without exception roll true to specifications and rejections are reduced to a minimum.

Forging blanks and the like produced by my improved method difier in their physical characteristics and particularly in the flow line arrangement of the material of the finished articles, from those produced prior to my invention. The flow lines referred to above and hereinafter,

' both in the specification andclaims, may be 'dereference is made herein particularly-to the longitudinal flow lines of the forging blank it will .be understood that flow lines would also appear on transverse sections of an article where the forming operations have caused lateral spreading or flow of the metal.

Flow lines on my improved article may be observed by cutting a longitudinal section through the rolled blank and then polishing and etching the cut surface. As is well known to those skilled in the art, the flow line arrangement or structure of a forged metallic article has an important bearing upon the strength and usefulness of the finished, article; Failure occurs more frequently in articles having cut or broken flow lines than in those in which the flow lines smoothly follow the contour of the article. In the Witherow type of blank, in which a flash is formed and thenremoved, the flow lines on planes through the flash are necessarily cut when the flash is removed. 'I'his results in'a' zone of weakness in the finished article and an undesirable structure. In the Witherow type of blank, or any blank formed with flash, the longitudinal flow lines on the plane of the flash are cut at each lateral enlargement or projection on the blank and even though the articlebe reforged the original cut flow line structure will persist and produce an inferior article as compared with applicants product in which the flow lines are' all substantially continuous throughout the length of the blank. In my blanks, which are formed without flash,

, the flow lines, as seen on any plane, either longitudinal or transverse, through a blank or string of blanks follow the contour of the blank and at no point are they cut or broken. Thus, my blanks have an ideal flow line arrangement.

While I have shown and described rolls which are set about A" apart. I do not limit myself to any such set, nor to grooves which approximate half the thickness of the rolled blank. With many articles, the roll set may be increased considerably above this example with consequent decrease in depth of the grooves in the rolls. However, there is a well defined limit to the maximum of the set or space between the rolls. The roll set should not be so great that effective control of the lateral dimensions of the small sections is lost. When excess flash is formed on the small sections during forging, the set is too great. In other words, efiective lateral control of the small sections is maintained when no excessive forging flash is formed during forging of those sections.

It will be understood from the foregoing disclosure of a preferred method of, and apparatus, for practicing my invention, that I have been able to produce from a long leader bar of uniform rectangular cross section, a string of connected but severable, substantially identical, complex, forging blanks, and that each blank is free from flash and severed flow lines with large generally rectangular sections, spaced apart from each other by smaller generally rectangular sections the lengths of some of which are longer than those of others, and that the dimensions of these large and small sections are accurate within the tolerances of a forging die in which the article is to be forged. It will also be observed that the large sections have their long cross dimensions 'in a plane substantially at right angles to the long cross axis of the smaller sections, that is, that the smaller sections project laterally beyond the sides of the large sections. The small sections are substantially symmetrical about a central plane therethru which is perpendicular to the narrow edges of the bar, and also about a central plane which is perpendicular to the narrow edges of the small sections. The

trailing ends of the long small sections are of sufficient size so that these parts of the blan fill the forging die.

In the preferred apparatus, the rolls are positioned very close to each other. The groove for the blank is formed partly in each roll andpreferably equally in each roll. The rolls are preferably matched, that is, they. are positioned with their grooves relative to each other, sothat the resulting blank will have the shape and dimensionsdesired. k

In the-preferred method, the long heated bar enters on edge between. the rolls and is propelled by the driven rolls. The rolls grip the narrow .edge of the bar, squeezing it down some-' what without material widening and the shallower parts of the groove squeeze the bar down further and 'flatten it, causing lateral flow of the metal into engagement with the side walls of the groove and also .causing lengthwise flow of the metal into unrolle'd parts thereof, that is,

in a direction opposite to that of the travel of the bar. In this manner the dimensions and shape of the smaller sections arecontrolled.

The term finish as used in conjunction with the expression forging blank appearing in the desire to secure by Letters Patent is defined by what is claimed.

What is claimed is- 1. The method of die rolling blanks having large and small sections accurately spaced from each other from leader bars in a single roll pass which lincludes passing a heated metal leader bar between similarly grooved rollers constituting a single die roll pass and having a maximum groove depth slightly less than the maximum corresponding dimension of the bar, maintaining the peripheral speed of the rolls above the speed at which longitudinal flow of the leader bar into previously rolled portions thereof may take place, and controlling and directing the lateral flow of the metal of the bar by confining the metal in matrix grooves having curved bottom surfaces in a manner to prevent the formation of flash and to maintain predetermined spacings between large and small sections of the blank formed by corresponding portions of the grooves in the rolls.

2. In the method of die rollin'g forging blanks having large and small portions accurately spaced from each other from heated leader bars of uniform cross-section in a single roll pass, the steps of passing a leader bar of uniform cross-section between a pair of die rolls having complementary grooves formed in the surfaces thereof and of a maximum depth slightly less than the maximum corresponding dimension of the bar with portions of said grooves varying in cross-sectional size and. shape to produce a plurality of similar articles having different cross-sectional sizes and shapes at different points, compensating for roll spring during the rolling operation on sections of great reduction to augment the gripping action of the rolls on the bar, controlling the longitudinal and lateral flow of the metal of the bar in a manner to prevent the formation of flash and elongation of previously formed sections of great reduction, and finally'severing the string of blanks into separate individual blanks.

3. A method of forming metal articles, comprising passing a heated leader between a single pass of die rolls adapted to form a string of connected blanks, forming accurately spaced large and small portions along the string adapted for forging, directing and 'controlling the flow of metal of the leader to prevent formation of flash integral with the blanks and the elongation of previously formed portions of great reduction, separating the blanks, and thereafter heating and forging at least certain portions of the blanks.

4. The method of forming metal articles which includes the steps of passing a heated metal leader bar on edge between a single pair of rolls, shaping the bar by said rolls into a plurality of substantially identical, integrally connected forging blanks, each blank having large and small generally rectangular sections accurately spaced from each other with the large sections extending beyond the surface plane of the adjacent small sections, directing the flow of metal of the bar during rolling longitudinally of the bar'between surfaces of the rolls while preventing the formation of flash or fins on the sides thereof and the elongation of previously formed sections of great reduction, and severing the rolled bar to separate the blanks.

5. The method of forming metal articles which includes the steps of passing a substantially rectangular heated metal leader bar on edge between a single pair of rolls, shaping the bar into a plurality of substantially identical, integrally connected forging blanks, each blank having large and small generally rectangular sections accurately spaced from each other, with each of the large sections being narrower in one direction and thicker in another direction than the adjacent small sections and projecting beyond one side of the adjacent small sections, by compressing the bar into recesses in the rolls while directing and controlling the metal of the bar between substantially parallel surfaces of the rolls so as to form uninterrupted longitudinal lines of flow during rolling while preventing the formation of flash or fins thereon and the elongation of previously formed sections of great reduction, and severing the rolled bar to separate the blanks.

6. The method of die rolling flash-free metal forging blanks having large and small sections spaced from each other therealong which includes the steps of passing a heated metal leader bar on edge between a pair of rolls in grooves having large and small sections, the maximum depth of the grooves being slightly less than the maximum corresponding dimension of the bar, maintaining the peripheral speed of the rolls above the speed at which longitudinal flow of the bar into previously rolled porti ns thereof may take place, controlling and directing the flow of the metal along unbroken longitudinal lines while preventing formation of flash or fin by confining the bar in the grooves certain portions of which have curved bottom surfaces and substantially straight sides.

7. The method of die rolling flash-free metal forging blanks having large and small sections accurately spaced from each other, which includes the steps of passing a substantially 'rectangular leader bar of substantially uniform cross-section on edge between a pair of rolls, slightly reducing the height of the bar and creating longitudinal flow lines therein by compressing it between the bottoms of circumferentially extending depressions in the rolls to form large substantially rectangular longitudinally spaced sections on the bar, greatly reducing the height of the bar between the large sections and forming substantially rectangular sections of less height and greater width than the large sections while continuing the flow lines and withoutforming fins or flash by compressing it between roll surfaces closer together than said spaced depressions, maintaining the peripheral speed of the rollsabove the speed at which longitudinal flow of the bar into previously rolled sections thereof will take place, and severing the rolled .u

bar to separate the blanks from each other.

8. The method of die rollinglarge, complex, metal forging blanks such as automobile front axles, internal combustion crank and cam shafts, and the like, which includes the steps of passing a heated, rectangular, metal leader bar on edge between a pair of die rolls, slightly reducing the distance between the edges of the bar at places spaced therealong without material lateral or lengthwise flow of the metal to form large generally rectangular sections, greatly'reducing the distance between the edge surfaces at other places along the bar with coincident flow of the metal laterally and lengthwise of the bar to form smaller sections between the large sections, limiting the extent of the lateral flow while preventing flash formation thereby making the smaller sections generally rectangular cross section,.and causing the lengthwise flow to 'take place in a direction opposite to that of the movement of the bar, thereby controlling the length of the smaller sections.

9. The method of die rolling large, complex. metal forging blanks such as automobile front axles, internal combustion crank and cam shafts, and the like, which includes the steps of passing a heated, rectangular, metal leader bar on edge between a pair of die rolls, slightly reducing'the distance between the edges of the bar at places spaced therealong without material lateral or lengthwise flow of the -metal to form large generally rectangular sections, greatly reducing the distance between the edge surfaces at other places along the bar with coincident flow of the metal laterally and lengthwise of the bar to form smaller sections between the large sections, restraining lateral flow of the metal when the metal has reached predetermined points beyond the sides of the largesections while preventing flash formation, thereby making the smaller sections generally rectangular cross section, and causing the lengthwise flow to take place in a direction opposite to that of the movement of the bar, thereby controlling the length of the smaller sections.

10. The method of die rolling large, complex, metal forging blanks, such as automobile front axles, internal combustion engine crank shafts, cam shafts and thelike, which includes the steps of gripping opposite edge surfaces of a heated, metal leader bar of substantially uniform, rectangular cross section between opposed surfaces of a single pair of die rolls, driving the rolls to propel the bar endwise therebetween, slightly reducing the distance between said edge at a plurality of places spaced along the bar to form large, generally rectangular sections, considerably reducing the distance betwe:n said edge surfaces and simultaneously widening the bar at other places to form smaller, generally rectangular sections, preventing the formation of flash along the smaller sections and controlling the dimensions of the smaller sections within the forging die tolerances by forcing portions of the adjacent side surfaces of the bar laterally against roll surfaces, directing flow of the metal lengthwise of the bar into rolled parts thereof, and severing the thus rolled bar into a plurality of forging blanks, each having a plurality of said large and small sections.

ll. The method of die roiling large, complex, metal forging blanks such as automobile front axles, internal combustion engine crank and cam shafts, and the like,,which includes the steps of driving a pair of die rolls having a die groove and thereby axially moving a heated, metal leader bar of substantially uniform rectangular cross section on edge in said groove between said rolls, slightly reducing the distance between opposite edge surfaces of the bar at places spaced along the bar to form generally rectangular large sections, greatly reducing the distance between said edge surfaces and simultaneously increasing considerably the width of the bar at a plurality of places along the bar to form smaller sections between said large sections, limiting lateral flow of the metal in the small sections and preventing flash formation by confining portions of the side surfaces of the metal in the groove to give said sections a generally rectangular shape, controlling the lengths of the small sections within forging die tolerances by driving the rolls at such a speed that the metal will flow lengthwise of the bar in a direction opposite to the direction of travel of the bar, and severing the thusrolled bar into forging blanks, each having a plurality of large and small sections.

12. The method of die rolling large, complex, metal forging blanks such as automobile front axles, internal combustion engine crank and cam shafts, and the like, which includes the steps of driving a pair of matched, similarly grooved, die rolls and thereby axially moving a heated, metal leader bar of substantially uniform rectangular cross section on edge between said rolls in said grooves, slightly reducing the distance between the edge surfaces with simultaneous increase in the width of the bar and lengthwise flow of the metal at a plurality of places along the bar to form smaller sections between said large sections, limiting the lateral flow of the metal and preventing flash formation on the smaller sections and giving them a generally rectangular cross sectional shape, by confining substantially the entire side surfaces of the metal of the smaller sections by the groove side walls, driving the rolls at such a speed that the direction of lengthwise flow of the metal will be opposite to the direction of travel of the bar thereby controlling the length of said small sections within the forging die tolerances and severing the thus rolled bar into forging blanks, each having a plurality of large and small sections.

13. The method of die rolling large, complex, metal forging blanks such as automobile front axlis, internal combustion engine crank and cam shafts, and the like, which includes the steps of moving a heated, metal leader bar of substantially uniform, rectangular cross section axially on edge into engagement between a pair of grooved die rolls, driving said rolls and thereby propelling the bar therebetween, slightly reducing the distance between the edge surfaces of the bar at a plurality of places spaced along the bar to form generally rectangular large sections, greatly reducing the distance between the edge surfaces at a plurality of places along the bar with coincident flow of the metal to form smaller sections joining the larger sections to each other, limiting lateral flow of the metal and preventing flash formation on the small sections thereby giving the smaller sections a generally rectangular cross sectional shape, driving the rolls at such a speed that the lengthwise flowof the metal will take place in a direction opposite to that of the travel of the bar thereby controlling the lengths of said smaller sections, and severing the thus rolled bar into forging blanks, each having a plurality of said large and small sections,

14. A string of substantially identical, complex 4 smaller sections being substantially symmetrical with respect to a. central plane therethru perpendicular to the narrow edges of the bar, and projecting beyond the sidesof the larger sections.

16. A die rolled, complex finished, metal forging blank free from flash and severed flow lines and having large generally rectangular sections and smaller generally rectangular sections therebetween, certain of said smaller sections being relatively long. axially and projecting laterally beyond the sides of the large sections, the said large and small sections and blank having dimensions which are accurate within the forging die tolerances for the blank.

17. A die rolled, complex finished, metal forging blank having sections which are large and generally rectangular in cross section and which are spaced from each other by sections which. are generally rectangular but smaller in cross section, the side surfaces of the larger sections lying in planes different from those of the side surfaces of the smaller sections the dimensions of said sections and blank being within the tolerances of a forging die therefor, said blank being free from flash and the severed flow lines, lean and twist, and having the characteristics of a blank which has been made by passing a heated bar on edge between a single pair of driven, grooved, die rolls. reducing the distance between the edge surfaces more in certain places than others along the bar and causing metal at the greatly reduced places to flow lengthwise of the bar toward unrolled parts of the bar.

blank being within the tolerances of a forging die for the desired article, each blank being free from flash, severed flow lines, lean and twist, and having the characteristics of a blank which has been made by passing a heated bar on edge between a single pair of die rolls; alternately reducing the distance between the edges of the bar slightly and greatly, confining the sides of the greatly reduced parts beyond the sides of the large sections and causing the metal at such parts to flow lengthwise of the bar toward unrolled parts thereof.

19. A. die rolled, complex finished, metal forg-' sections lying in planes different from those of the side surfaces of the smaller sections the dimensions of said sections and blank being within the tolerances of a forging die. therefor, said blank being substantially free from flash, severed flow lines, lean twist, and underfilling at the trailing endsof the longer small sections, said blank having the characteristics of a blank which has been made by passing a heated bar on edge in an approximately surrounding groove between a single pair pf driven die rolls with alternate large and small reductions of the distance between the edge surfaces and coincident restrained lateral, and also lengthwise flow of the metal at the places of large reduction toward unrolled parts of the bar.

THOMAS N. SLOAN.

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