US2825251A

US2825251A - Method of rolling metal

Info

Publication number: US2825251A
Application number: US299795A
Authority: US
Inventors: Lee P Rader
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-07-19
Filing date: 1952-07-19
Publication date: 1958-03-04
Anticipated expiration: 1975-03-04

Description

March 4, 19584 L. P. RADER 2,825,251

7 METHOD OF ROLLING METAL Filed July 19, 1952 5 Sheets-Sheet 1 I N VEN TOR. [5 Q @4052 March 4, 1958 w 7 L. P. RADER v2,825,251

ME OF O IN METAL.

Filed July 19, 1952 5 Sheets-Sheet 2 172 8.1701 Y P INVENTOR.

March 4, 1958 L. PTRADER 2,

' METHOD OF ROLLING METAL Filed July 19. 1952 Y 5 sneets sneet s a o I 34 .96 Q 78 7s 75 45 v o a2 90 74 ffim 78 82 I 70' Y -72 60D INVENTOR. .Zss l2 2.9052

- Mam 4, 1958 L. P. RADER 2,825,251 METHOD bF ROLLING METAL F'ilec'l July 19, 1952 '5 She ets-Sheet 5 fidfli r1 4 STAT/042v DIE f 1 I I I i( I my 15 L Mow/M0 DIE 5 Q64 3 I V X;

- 1 I r l '2" 5 &

L I L o I y I I /2 INVENTOR.

United States Patent METHOD OF ROLLING METAL Lee P. Rader, Norwalk, Calif.

Application July 19, 1952, Serial No. 299,7 95

7 Claims. (Cl. 80-60) This invention relates to a method of rolling metal and more particularly to a method of rolling generally cylindrical or round metal blanks to produce diiferent shapes.

Heretofore, methods have been developed for shaping blanks which are cylindrical or round in cross section to form shapes commonly exemplified by screws and bolts or the like. Thread forming by rolling has been confined to the simple displacement of relatively small amounts of metal in the blank to adjacent areas and simultaneously forming a thread or other projecting shape during the displacement operation.

However, it has heretofore been impossible to displace relatively large amounts of metal or to control the direction of displacement by rolling. Where relatively large grooves or outward skirts or other projections have been formed; where the metal had to be formed into a particular shape; where a ridge without a groove was desired; or where ridges were formed with no grooves of less diameter than the blank, it was found necessary to machine them. Such operations can be formed in an automatic screw machine but production with such a machine is much slower and more costly than production through rolling methods.

.One of two great difliculties encountered prior to my invention in rolling relatively large amounts of metal to displace portions of the blank axially and outwardly, has been due to the fact that the displaced metal was formed to its final shape during the displacement operation. The other was that there was no way of displacing metal to move in the desired direction. This resultedv in the need for such excessive inward radial pressures on .the blank between the dies that the pressures exceeded the compressive strength of the blank. It also resulted in the displacement of metal forming approximately equal ridges on both sides of the notch and pre- Vented the formation of special shapes. 7

I have conceived a method of displacing relativel large quantities of metal by rolling wherein displacement is accomplished in one direction only or in two controlled directions axially of the blank and wherein the displaced metal is unconfined during such displacement, thereby greatly reducing the compressive loads on the metal of the blank, but with the direction of displacement being controlled so the diameter of the blank can be held on one side of the groove. I provide a bearing surface adjacent the displacement surface of the dies to provide the traction necessary to' displace relatively large quantitles of metal. Also, another form, of my method involves the billowing of metal axially. Billowing comprises a continuous series of displacements wherein axially displaced increments in turn displace next successive increments of metal in the blank. This provides a final ridge or skirt remote from the point where the'original billowing is begun. e

Other objects and advantages of the method will become apparent from the following "detailed description but basically the method involves displacing of metal in Fig. 6 is a side elevational view of the die of Fig. 1; Fig. 7 is a diagrammatic view illustrating the general action of a pair of dies for practicing themethod;

Figs. 8 and 9 are views of two blanks with the dies in section and indicating a desired example of the angle of attack of the displacing surface of the die;

Fig. 10 is a plan view of another form of the die;

Figs. 11 through 14 illustrate the steps of forming a shape from the die of Fig. 10;

Fig. 15 is an end view of a die for the purpose of 1 illustrating a desired angle of displacement surface;

the blank and controlling the direction of displacement Figs. 16, 17 and 18 are views illustrating the efiect of variations in the angle of the displacing surface of the die;

Fig. 19 is a diagrammatic view illustrating the relative points of contact between the two dies and the blank;

Fig. 20 is a view showing an improper relationship between the complementary metal displacing ridges of a pair of dies;

Fig. 21 is a view illustrating the proper relationship between the ridges on the die with regard to the relative points of contact indicated in Fig. 19;

Fig. 22 is a plan view of a die illustrating in another manner the relative points of contact between two dies and the rolling blank;

Fig. 23 is a plan view of a die with a serration former incorporated therewith;

Figs. 24 and 25 are views illustrating the use of'the serrations formed by the die;

Figs. 26 through 31 are illustrative of faults which may be encountered by the use of improperly shaped dies;

Fig. 32 is an enlarged detail of a portion of a die and showing it engaged in displacement by billowing;

Fig. 33 shows the dies and a blank in the beginning of abillowing operation;

Fig. 34 is a plan view of a die such as used in billowing;

Fig. 35 is a plan view of the stationary die of a pair indicating the starting point of the roll thereon;

.Fig. 36 is a diagrammatic view of a pair of dies with the blank at the beginning of the rolling operation;

Fig. 37 is a plan view of the moving die of the pair in 36 and indicating the starting point thereon.

It will be seen by my drawings that the metal which is displaced by the formation of grooves is moved to one side of the groove while the other side is held at the original diameter.

Figs. 1 and 6 illustrate a die 70 which is one'of a complementary pair and Figs. 2 through 5 illustrate the action or" dies such as the die 70. The complementary die is shown in Figs. 2 through 5 at 72. The dies have projecting

ridges

74 and 75 which displace metal to make a groove 76 in the cylindrical blank 78. This ridge is shown in Fig. 1 to be disposed at an angle to the longitudinal axis of the die and this angle makes the ridge 74 very slight at the wall end of the die and at the beginw that point is uniform, and at 7012 the ridge has assumed Patented Mar. 4, 1958 a height which beyond that point is uniform. The angulation as shown in Fig. 1 and the gradual increase in height as illustrated in Fig. 6 produce a gradual facing of all the displaced metal in-the desired direction, the blank 78 being held between the

dies

70 and 72 in such a way that there is no axial movement of the blank relative to the dies.

While displacement of metal by rolling might appear, at first glance, to be a continuous process, each part of the mass of metal being displaced is actually successively periodically engaged by the dies during the rolling operation in a series of passes, because the rolling of the Work piece relative to the dies permits each die to operatively engage only a relatively small peripheralportion ofthe work-piece at. any giventime. This intermittent engagement of the dies with each part of the displaced mass is illustrated in. Figures 19 and 22, and is more specifically described in the following discussion.

When point on the blank or part 78 beingrolled leaves point g on the moving die 70 in Fig. 19, it has been shaped approximately as shown at f inFig. 21. Point 1 on the surface of the part 78 will be out of contact with the dies until the part or blank 78 has been revolved nearly onehalf revolution when point f comes into contact with the stationary die 72. By this time, the blank 78having'made its nearly one-half revolution, contact with the stationary die 72 is made at point It in Figs. 19 and 22. The point h is a distance farther back on the stationary die 72 equal to nearly one-half the circumference of the blank 78 and will be formed approximately as in Fig. 21. Since the forming edge of ridge 75 is located diagonally on the face of the stationary die 72, the point h (where point f resumes contact) will be higher than point g on the moving die 70. As a result, the angle shown in Fig. 22 at which the forming face of

ridge

74 or 75 is disposed and the angle at which it increases in height must be calculated in a given case so that when point 1 on the blank 78 comes into contact with the stationary die 72 at point It, there will be sufficient overlapping of the ridge 75 on the stationary die 72 and the displaced mass being moved. If insufiicient overlapping is permitted or if the ridge is not properly shaped, the ridge 75 will start a new groove as shown by

ridges

74a and 75a in Fig. 20.

When metal is being moved in one direction, there is obviously a pull exerted on the neck of the blank which is formed by the groove in the blank. If the part is required to have a deep notch or groove, leaving a neck of small diameter, then axial pull may be enough to cause the neck to stretch or even completely fail under tension. The tendency to do this can be reduced by properly regulating the angle of the slanted leading faces 80 and 82, Fig. 17, on the leading faces of the

ridges

74 and 75. Referringnto Figs. 15, 126, 17 and 22, the tendency to stretch the neck at the notch or groove 76 can be controlled. A method of control is shown in Figs. 16, 17

and 18 wherein the indicated angles of 30, 45 and 60 are shown on the slanted displacing surfaces 86 of the moving die 70. Where the indicated angle of 30 in Fig. 16 is used, the approximate pressure exerted is dis posed in such a way that the axial tensile load is equal to 86.6 percent of the displacing surface force and the compressive load is 50 percent of the displacing surface force. Where, as in Fig. 17, the indicated angle is 45, the theoretical applied force is divided equally between axial tension and compression. Where the angle is 60, as indicated in Fig. 18, the axial tensile load is 50 percent of the displacing surface force and the compressive load is 86.6 percent of the displacing surface force.

In Fig. 16, the line of arrows SS is at right angles to the metal displacing surface 86, showing more of an. axial thrust than that in Fig. 17, where the displacementsurface angle is 45 to a plane perpendicular to the axis of the blank 78. In Fig. 18, the line of arrows 92 shows much more of a transverse compressive force on the blankmamas-1.

where the line of arrows point to the angle of the displacement surface is 60 as indicated.

The dies 76 and 72 are shown with

grooves

94 and 96 into which the displaced metal can flow freely. The grooves are so placed that they lie in the natural path of a reasonably unobstructed movement of the displaced metal. Referring to Fig. 18, it will be seen that the natural path of movement for the displaced metal will be in the direction of a corner 98 of the parent metal in the blank 78. To force a unit of displaced metal past this corner obstruction into die groove 100 will take con siderably more total pressure than to move the same unit of displaced metal along its natural and unobstructed path quired to .displace'a given unit of metal in the arrange,

ment of Fig. 18 would be considerably greater than the sum of the two loads required in the arrangement of Fig. 16.

The amount. of pressure which the parent mass can withstand. is generally the limiting factor as to how much metal can be displaced and the rate of such displacement. For this reason, when a 60 angle as in Fig. 18 is used, either for the purpose ofreducing the tensile load or for some otherreason, the rate of penetration of the displacing

ridge

74 or 75 as well as the degree of displacement must be reduced to compensate for the added pres sure required, In displacing metal from a groove in the blank to a ridge on the blank, it is generally desirable to apply pressure, as nearly as possible, in a direction at right angles to the axis of the part.

If the desired finished part requires that the diameter of the blank on 'both sides of the groove and the metal displaced therefrom be held accurately, and the, tensile strength of the neck or weakest portion of the blank is insufficient to safely withstand the axial displacement force, considerable support' can be provided by the use of lateral ridges 104 and grooves 106, Figs. 24 and 25. These ridges and grooves are formed by a similarly shaped part 108 on a die 110 shown in Fig. 23. The ridges 108 on the the 110 need ,be carried lengthwise of the die generally ,to the point where axial displacement is completed and, of course, axial tension is relaxed.

The ridges; 104 and grooves 106 on the blank as shown in Figs. 24 and 25 are of shallow wave'like form and are such that they can be rolled out smoothly by a portion 112 of the die llstl'lin Fig. .23.

The depth of the wave-like serrations or grooves 106 in the blank can, for example, be approximately onetenth' of the pitch shown at j inFig. 25. A depth of serration of groove 106' in a cylindrical blank, which is three thousandths to five thousandths of an inch, is generally sufiicient and a pitch j of approximately one-sixteenth inch is preferred. This. example is given fora small blank whose diameter is on the order of one-eighth of an inch. Howeventhe figures given above are not critical but merely exemplary. Ridges or serrations formed as described will ofier substantial support. for the blank against axialmovement but will ironout smoothly when the blank reaches the die portion 112 shown in Fig. 23.

It is generallydesirable that the side 77 of the displacing ridge 74 as' in Figs. 1,. 3 and 4 opposite the direction into which the: displaced metal is being moved, be wholly :or partially 'at an angle, as in Fig. 28, or on a radius 77a asshown in'Fig. 27. Such angle or radius will prevent shaving a thin chip 114 from the upper side of thegrooveias' would occur from the structure shown in Figs.,26 and29 and asis best illustrated in Figure 29. Such a chip wouldibe pressed into the parent mass and would-.spoihthe appearance: and likely set up incipient fractures underneath it as shown in.Fig.'3l. A sharp corner will also have a tendency to crumble and to interfere with proper performance and life of the die.

It will readily be understood by those skilled in the art that the volume of metal taken from the groove in the part must be slightly in excess of the volume of metal required for the ridge on the part. This excess is generally between five and ten percent of the displaced metal and is required because of factors of compression and elongation. Tolerances should always be provided in the dimensions of the groove or the ridge on the part to enable final adjustment. If too much metal is accumulated in the forming groove of the die, this excessive metal will form into bulges at the points where the ridge on the part leaves the forming groove in the dies or set up compressive forces which exceed the compressive strength of the parent mass and cause a compressive fracture, similar in appearance to a pipe in a casting, generally located in the core or axial center of the part. If insufficient metal is provided in the forming groove, the ridge on the part will, of course, be incompletely filled and will have a line similar to an incompletely filled thread on a screw. In order to provide a substantially uniform relation between the volume of metal taken from the groove and the volume of metal in the finally formed ridge or collar for any particular pair of dies, I prefer to use blanks having substantially the same diameter with any particular set of dies.

The method for the axial movement of a thin surface layer of metal into a solid mass can best be described as billowing the metal. To accumulate a sufiicient mass of metal to produce a substantial ridge by displacing a thin outer layer of the blank, the required area of thin outer layer would be much too great to be displaced as a unit.

It will be equally apparent that metal from the far end of the outer layer could not be moved axially for the necessary distance to become part of the mass contained in the ridge. These problems are overcome by the method referred to as billowing the metal. As shown at136 in Fig. 33, a narrow strip of the outer layer metal is displaced by radially inward pressure upon the periphery of the part. This displaced metal is forced down into the parent mass of metal by pressure from a broader section 138 of the die in Fig. 33, displacing other metal at that point as shown at 140. Since each impression of the die reduces the diameter of the part, it can readily be seen that the mass of metal being displaced becomes cumulatively greater. It is also apparent that since the mass of metal displaced by each impression is forced back into the parent mass and displaces other metal from the parent mass, it is not itself moved on.

This principle is what makes it possible to accumulate the necessary mass to form a substantial ridge from the 7 thin outer layer.

To provide a continuingly broader pressure point on the dies, as shown at 138 in Fig. 33, the face of the dies may be relieved at an angle as shown at 142 in Fig. 34. In order to avoid folds which would leave spiral lines on the surface of the part, the billowing edge 142 may be shaped at an angle of as shown in Fig. 32. The length of this angle should be approximately ten percent longer than the axial movement of the thickness increase 138 in Fig. 33 in one-half the circumference of the part.

The compressive pressure exerted upon the metal to be displaced must very nearly approach the compressive strength of the parent mass since both are the same material. It being due only to the fact that the pressure is applied at a concentrated point and is diffused as it recedes from the point of application, that surface displace ment of metal is at all possible. In the displacement of a, small thread upon the surface of a large parent mass, such as a screw blank, diffusion of pressure is an unimportant factor. The possibility of a .compressive failure Of th pat n mass pccurs only. in. such cases where the actual pressure required to form the thread is greatly exceeded. g

In the forming of some of my parts, the opposite is frequently the case. In some experimental parts, made by the methods disclosed herein, the area in cross section of the metal displaced has sometimes exceeded the area of the metal remaining in the parent mass by a ratio of 2 to 1. It is apparent, therefore, that since the mass of metal that is being displaced is so much greater in proportion to the metal remaining in the parent mass, it must absorb much more pressure than is the case in screw threads or such other forming of this general nature, that precautions must be taken in designing the dies, to avoid applying pressures which would exceed the compressive strength of the remaining parent mass.

A clearance groove 164 in the die, as shown in Figs. 2 and 3 may be provided in the area adjacent to the displacement into which the metal may move freely. This groove should be large enough so there will be no confinement of the displaced metal moving into it. Any confinement of the metal while moving into the groove would add substantially to the pressure required to displace it. Since the displaced metal generally moves in a direction at right angles to the direction of the force applied,'as shown in Figs. l6, l7 and 18, any obstruction to its movement would have to be overcome by pressure indirectly applied, so that it would have to be substantially greater at the point of application than its effect at the point of interference. A rough thinning down of a mass of displaced metal as it is moving into the groove, as shown in- Fig. 9, instead of permitting it to accumulate in an entirely uncontrolled manner, can generally be 'done if the die is properly designed without producing more than negligible obstruction to the moving metal if the groove is deep enough, so that there is no confinement involved.

If the pressure applying surface 86 in Fig. 16 is at the obtuse angle shown, the displaced metal will tend to move, afterthe initial penetration, very much as shown in Fig. 6. By the time full penetration is reached, the mass will generally skirt outward as shown in Fig. 3. If the metal receiving groove is narrow as shown in Fig. 9 and the direction of application of pressure is not more than 30 measured from an axial line as shown by the lines of arrows in Fig. 8 the application of force is sufficiently direct to the axial direction of deformation interference that it will not prevent successful displacement. If, however, radial confinement were attempted, the direction of the application of force would be approximately from the direction of the deforming interference which is directed radially inwardly, as indicated in Fig. 9, and would in many cases cause the pressure applied to exceed the compressive strength of the parent mass.

The final shaping of the ridge to the desired form must generally be done after the displacement has been completed, and the necessary volume of metal has been completely placed in the forming groove of the die whether by the displacement from the groove of the part or by billowing the metal from the outer shell of the part.

I have illustrated dies for accomplishing both the rough forming and final shaping in Figures 7 and 10 to 14, Figure 10 illustrating the face of one of the dies shown in progressive sections in Figures 11 and 18.v

The most effective method for this final forming depends upon the final form of ridge or skirt desired on the part. To produce ridges or skirts with parallel top and bottom surfaces, it is most desirable 'to roughly formthe metal in the manner shown in Figures 11 and 12, by the method heretofore described, so as to extend the diameter to a degree greater than the desired diameter on the finished part. This permits the packing of the metal to produce a solid smooth ridge by reducingthe depth 7 in the finishing portions 164 of the die groove 166, as shown in Figs. 7, 11, 12, 13 and 14. This not only per- 7 mits achoiceofradii or other shapes on the perimeter of the ridge but is also the most successful from aforming: standpoint.

When the metalis being packed to. producea solid mass with. a good finish,uit is under a high degree of pressure. Iftthis pressure were applied by bringing the two parallel sides 168 in .Fig. 13 axially together, the grip produced by so .:much pressure applied axially in this way would be likely toprevent the necessary slippage to compensate for the difference between the larger diameter of the ridge170 and the smallerdiameter of the parentpart. Since the part revolves as a unit, it must be realized-that the surface speed of the two diameters is different and unless'a provision .is made for slippage, the part will break either at its weakest point or at the point of greatest strain,

I therefore finish form thepart by bringing bottom portions 172 of die grooves166 radially inwardly from their relatively large diameter of Figure 13 to their final, smaller diameter of Figure .14. This reduction of the diameter of the bottom portions 172 of die grooves 166 is also well illustrated by Figure 7. This mode of operation keeps slippage interference at a minimum.

In finish forming ridges of the type which have either one or both of the upper and lower sides at an angle, the problem of slippage is not critical when pressure is applied upon upper and/or lower surfaces. Also, in shapes of this type, where a sharp edge isudesired, it would not be possible to produce the pressure by reducing the diameter. There is, moreover, a considerable problem in forcing the metal into a sharp corner with a small included angle. The method preferred for this form is to apply the pressure from the tapered side or sides, starting to apply the pressure at a point 176 adjacent to the parent mass in Fig. 12, and 178 in Fig. 13, and working gradually outward to the periphery as shown in Fig. 14. Where a saucer shape is desired, the method for applying pressure is the same as for a conical shape. The difference being that in this instance, the side of the groove in the die which would be supporting the side of the ridge that is to be hollow, must be relieved to permit a spinning down of the ridge.

The lengths of the two dies in a mating pair for most reciprocating types of thread rolling machines are unequal, the amount of difference varying with different sizes of machines. This must be taken into consideration in design of any dies with a diagonal ridge. These machines are generally so designed that a transfer finger 180 in Fig. 36 feeds the part and a starting finger 182 starts the part between the dies at a point generally referred to as the match point in the dies shown at centerline vFigs. 35, 36 and 37. This matchpoint on the stationary or short die islocated at the starting end of the face, as shown by centerline y, Figs. 35, 36 and 37. The proper matchpointon the moving or longer die is properly located by subtracting the length of the sta tionary or short die 184 from the length of the moving or long die 186 and then dividing the length difference by two. One-half of this total difference in length of the two dies added to the total length of stationary or short die provides the dimension for locatingthe the match point on the moving die when measuring from the finishing end of the moving die. The location of the matchpoint on the moving die should alwaysbe taken from the finishing end rather than the starting end because the finishing end seats against a solid wall in the die pocket and is, therefore, the portion which controls the position of the matchpoint. Thus,,the overhang x on the front end of moving die 186 in Figure 37 is equal to onehalf of the total ditference in length of the two dies 184 and 186. A similar overhang of length x (not shown) is positioned at the other end of moving die 186. No overhang is present at either end of the stationary die 184. Thus, the diagonal ridges on the dies 184 have the same length v taken from .centerline y and also have the same width 2 and the same angle z with respect to the longitudinal axes of the dies 184 and 186. As an we amplero'f the relative dimensions of the dies 184 and 186, 'and. ofsthedie ridges, if the stationary die 184 is four inches long and the moving die five inches long, the lengthv of the ridges onboth dies will be four inches, and thewlength x of the overhang at each end of the moving die willbe one-half inch.

At 188 in Fig. 36 is shown an end stop of a type well known in theart. It is always advisable to use such an end stop in form rolling when diagonal ridges are involved, so as to avoid the possibility of starts ahead of or behind the propermatchpoint on the moving die. An

improper start is likely to produce a condition similar to that shown in Fig. 20.

If the displacement of metal in the required form is extensive, it is generally desirable to use the thread rolling machine next larger in size than the one normally used for a screw of the same diameter as the desired formed part. will do.

Most form rolling dies require a bearing surface, such as at 79 in Figs. 2 through 5, on the dies which surfaces bear against the part above and below the section being formed. These surfaces may be etched with acid or sandblasted for better traction, but when this is done, the forming ridges and grooves should be suitably masked so these parts will retain the smoothest possible surface. This is necessary to permit the slippage which compensates for the difference in surface speed of larger and smaller diameters on the same unit.

It will, of course, be understood that the method is capable of various changes and modifications other than those disclosed without departing from the spirit of the invention.

I claim:

1. The method of rolling a cylindrical metal blank between a pair of rolling dies to displace metal axially along the blank, which includes establishing an annular shoulder on the blank, engaging said shoulder and progressively moving it axially along the blank with a die projection edge disposed at an angle relative to the longitudinal axis of the dies, each point around the circumference of said shoulder being successively engaged and axially moved by aplurality of successive passes of said die projection against it as the blank is rolled between said dies, and holding said blank on both axial sides of the metal being moved against axial movement of said blank relative to said dies during the axial movement of the metal along the blank.

2. The method of rolling a cylindrical metal blank between apair ofrolling dies to displace metal axially along the blank, which includes establishing an annular shoulder onthe blank, engaging said shoulder and progressively moving it axially along the blank with a die projection edge disposed atan angle relative to the longitudinal axis of the dies, each point around the circumference of said shoulder being successively engaged and axially moved by aplurality of successive passes of said die projection against it as the blank is rolled between said dies, holding said blank against axial movement relative to said dies during the axial movement of the metal along the blank, and shaping the displaced metal by confining it within a die groove after the displacement has been accumulated.

3. The method oflrolling a cylindrical metal blank between a pair of rolling dies to displace metal axially along the blank, which includes establishing a thin annular shoulder on the blank, engaging said thin shoulder and progressively moving it axiallyalong the blank with a dieprojection edge disposed at an angle relative to the longitudinal axis of the dies to displace a thin outer layer of the metal of the blank axially along the blank, each point around the circumference of said shoulder being successively :engaged and axially moved by a plu If displacement is limited, the same size rality of successive passes of said die projection against it as the blank is rolled between the dies, said successive passes of the die projection successively forcing increments of said thin displaced outer layer of the metal back into the parent mass of the blank to successively displace further surface increments of the metal of the blank axially along the blank, and holding said blank on both axial sides of the metal being moved against axial movement of said blank relative to said dies during the axial movement of the metal along the blank.

4. The method of rolling a cylindrical metal blank between a pair of rolling dies to displace metal axially along the blank, which includes establishing an annular shoulder on the blank, engaging said shoulder and progressively moving it axially along the blank with a die projection edge disposed at an angle relative to the longitudinal axis of the dies, each point around the circumference of said shoulder being successively engaged and axially moved by a plurality of successive passes of said die projection against it as the blank is rolled be tween said dies, holding said blank against axial movement relative to said dies during the axial movement of the metal along the blank by forming shallow annular serrations in the blank and operatively engaging these in complementary longitudinal die serrations, and shaping the displaced metal by confining it within a die groove after the displacement has been accumulated.

5. The method of rolling a cylindrical metal blank between a pair of rolling dies to displace metal axially along the blank, which includes establishing a pair of oppositely directed annular shoulders on the blank, engaging one of said shoulders and progressively moving it axially along the blank with a die projection edge disposed at an angle relative to the longitudinal axis of the dies, each point around the circumference of said shoulder being successively engaged and axially moved by a plurality of successive passes of said angular die projection against it as the blank is rolled between said dies, holding said blank against axial movement relative to said dies during the axial movement of the metal along the blank by operatively engaging the other annular shoulder on the blank with a die projection edge disposed in substantial alignment with the longitudinal axis of the dies, and shaping the displaced metal by confining it within a die groove after the displacement has been accumulated.

6. The method of rolling a cylindrical metal blank between a pair of rolling dies to displace metal axially along the blank, which includes establishing an annular shoulder on the blank, engaging said shoulder and progressively moving it axially along the blank with a die projection edge disposed at an angle relative to the longitudinal axis of the dies, each point around the circumference of said shoulder being successively engaged and axially moved by a plurality of successive passes of said die projection against it as the blank is rolled between said dies, holding said blank on both axial sides of the metal being moved against axial movement of said blank relative to said dies during the axial movement of the metal along the blank, and shaping the displaced metal by confining it within a die groove after the displacement has been accumulated.

7. The method of rolling a cylindrical metal blank between a pair of rolling dies to displace metal axially along the blank, which includes establishing a thin annular shoulder on the blank, engaging said thin shoulder and progressively moving it axially along the blank with a die projection edge disposed at an angle relative to the longitudinal axis of the dies to displace a thin outer layer of the metal of the blank axially along the blank, each point around the circumference of said shoulder being successively engaged and axially moved by a plurality of successive passes of said die projection against it as the blank is rolled between the dies, said successive passes of the die projection successively forcing increments of said thin displaced outer layer of the metal back into the parent mass of the blank to successively displace further surface increments of the metal of the blank axially along the blank, holding said blank against axial movement relative to said dies during the axial movement of the metal along the blank, and shaping the displaced metal by confining it within a die groove after the displacement has been accumulated.

References Cited in the file of this patent UNITED STATES PATENTS 319,755 Simonds June 9, 1885 368,688 Rogers Aug. 23, 1887 1,327,525 Curtis Jan. 6, 1920 1,913,143 Robertson June 6, 1933 2,042,552 Roeckner June 2, 1936 2,126,912 Murden Aug. 16, 1938 2,172,553 Tripp Sept. 12, 1939 2,180,555 Sipe Nov. 21, 1939 2,235,255 Durant Mar. 18, 1941 2,280,686 Colwell Apr. 21, 1942 2,291,408 Pearson July 28, 1942 2,596,962 Stern May 13, 1952 FOREIGN PATENTS 5,336 Australia Dec. 24, 1926 14,387 Great Britain May 26, 1904 24,641 Austria June 25, 1906 232,964 Great Britain Mar. 11, 1926 360,767 Germany Sept. 25, 1920 498,412 Germany Feb. 6, 1926