Method of forming cylinder ends

Oct. 1, 1946.

J. J. BEDNAR ET AL

METHOD OF FORMING CYLINDER ENDS

2,408,596

Sheets-Sheet 1

Filed March 13, 1944

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Oct. 1, 1946.

J· J. BEDNAR ET AL.

METHOD OF FORMING CYLINDER ENDS

Filed March 13, 1944 o .

Sheets-Sheet 2

2,408,596

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Patented Oct. 1, 1946

2,408,596

UNITED STATES PATENT OFFICE

2,408,596

METHOD OF FORMING CYLINDER ENDS

J os eph J. Bednar and Steven P, Peck, McKeesport, Pa., assignors to National Tube Company, a corporation of New Jersey

Application March 13, 1944, Serial Νθ· 526,253 (Cl. 29—148.2)

Claims.

dition of the tube or cylinder and the different stages in the operation of the method.

Figure 7 illustrates a step in the method wherein the mid-portion of the built-up metal of increased thickness is forced inwardly into engagement with a die member.

Figure 8 illustrates the step of removing feather-like portions resulting from the operation of Figure 7,

Figure 9 is a detail portion of an end of a cylinder made in accordance with the herein claimed method.

Referring in detail to the drawings, 10 represents a conventional form of chuck adapted to grip a tubular or cylindrical workpiece (2. This chuck is rotatably supported by a suitable spindle 14 of conventional form which is rotated by any suitable means such as a belt 16 connected to a power drive (not shown). The chuck and its driving means are adapted to rotate the tubular workpiece 12 at a speed of approximately 1400 R. P. M. Mounted in juxtaposition with the chuck 10 is a tool bed 18 having slidably mounted thereon a table 20 which can be reciprocated back

This invention relates to an improved method of- spinning integral ends on cylinders to adapt them for- high-pressure service.

Heretofore the spinning of cylinder ends has been quite definitely restricted to use on small cylinders suited only for low-pressure work. One object of the present invention is to provide a method for building up the thickness of an end section of a tube or cylinder which will adapt it for high-pressure service.

A further object is to provide a method involving the building up of the end thickness of a cylinder by spinning and subsequently eliminating the fissure or feathers formed in the region' of the original point of juncture of the end edges. 15

As will appear more fully hereinafter, our improved method involves spinning integral closed ends on tubular metal workpieces to form a closure capable of withstanding a pressure of 2500 pounds per square inch or greater, the method 20 being characterized by rotating the workpiece while applying a work-engaging tool to the end portion thereof, moving said tool through arcs extending from the periphery toward the longi- :

tudinal axis of the workpiece, also moving the 25 and forth by any suitable means in the direction tool axially of the workpiece, to bring the end edges of said workpiece forcibly into abutment in the region of the longitudinal axis thereof, and thereafter continuing the movement of said __________ ____ ________________ ______ __ tool in arcuate paths extending from the periph- ³⁰ which supports a tool holder 28 carrying a tool ery to a point beyond the longitudinal axis of the workpiece, so as to upset said end portion and build up metal of increased thickness without a fissure outside the original point of juncture of said edges, then stopping the rotating and thereafter pressing the mid-portion of the closed end inwardly into engagement with a die member having an axial recess opposite the point of juncture of said edges, whereby feather-like portions in the axial region adjacent said point of juncture are pressed into said recess, and thereafter removing said feather-like portions.

For a full understanding of the invention, reference should be made to the following detailed disclosure, the accompanying drawings, and the appended claims.

In the drawings:

Figure 1 is a plan view of conventional apparatus suitable for carrying out the present invention.

Figure 2 illustrates an initial step of the improved method.

Figures 3, 4, 5 and 6 are views partly in elevation and partly in section, illustrating the conlengthwise of the work.

A compound tool rest 22 is pivoted at 24 at a point eccentric to the longitudinal axis of the workpiece 12. The tool rest carries a slide 26 which is preferably, although not necessarily, in the form of a roller pivotally mounted in a bearing 32, so that the tool can make a rolling contact with the end portion of the tubular work35 piece 12. Prior to the operations about to be described, the end portion of the workpiece will usually be locally heated, for example, by the impingement of flames from oxyacetylene torches such as indicated at 34 and 36. The torches are effective to maintain the end of the workpiece at the optimum spinning temperature of approximately 2000° to 2200° F. The torch 36 is mounted adjacent the compound rest 22, and the torch 34 is mounted on any stationary portion of the apparatus.

In starting the improved method, after the work is properly heated, the tool 30 is moved to the position of Figure 2, where the leading edge of the periphery of the tubular workpiece is engaged. After such engagement the tool rest 22 is swung about its pivot 24; for example, from the position of Figure 2 to the position of Figure i3, through the arcuate path indicated by the dotted arc x—y, the tool at this time swinging about a radius r struck from the center 24 which,

2,408,596 as shown, is in plan and is offset from the longitudinal central axis of the workpiece 12.

The tool 30 is moved back and forth along its arcuate path several times, with the result that metal from the outer normally cylindrical portion is flowed inwardly, thus thickening the end region of the tube from .the normal gauge of the workpiece to the thickened condition suggested in Figure 3. Subsequent arcuate sweeps of the tool 30 with an accompanying endwise movement of the tool toward the work gradually spins in the end of the tube until it is substantially closed, as shown in Figure 4. The arcuate stroke of the tool 30 is then increased to the position such as suggested in Figure 5, thus completely closing the tube end and bringing the end edges initially into abutment in the immediate region of the longitudinal axis of the workpiece 12. At this stage of the method, there will be present a fissure f in the zone of initial abutment of the end edges of the tube. Thereafter the tool 30 is given a plurality of additional arcuate sweeps to the position indicated in Figure 6, where the working face όϊ the tool crosses the longitudinal axis of the end of the workpiece. This is for the purpose of building up worked metal of substantial thickness without a fissure, beyond the original point of juncture of the end edges. This condition is illustrated in Figure 6, wherein it is noted that the fissure ends at the point and the metal beyond that point is entirely devoid of a fissure and is thus rendered more dense so that it is thereby made capable of withstanding’ considerable pressure.

Upon completion of the operation represented in Figure 6, the workpiece is removed from the chuck 10 and the end thereof is entered into the cavity 38 of a die 40. Thereupon another die 42 having a central recess 44 therein is forced inwardly, with the result that featherlike portions 46 located in the longitudinal central axial region of the workpiece and flanking the central fissure, are forced inwardly into, the recess 44 of the die 42. The die 42 is then removed and the work-piece is disengaged from the die 42. The workpiece is then chucked in a suitable metal working tool such as a lathe or the like, and a cutter bar 48 centered by a guide rest 50 and carrying a spade or similar cutting tool 52 is brought into play, so as to machine off the projecting feather-like portions which flank the fissure. At the conclusion of this operation the interior of the cylinder will have the finished face 54 and the exterior will have a dished cavity 56, as shown in Figure 9.

It will be understood that in the machine operation of Figure 8, the feathers 46 flanking the fissure will be eliminated. Thus the end closure or bottom of the cylinder is a dense homogeneous solid section free from physical defects and sufficient to withstand high commercial test pressures of the order of 2500 to 3500 pounds per square inch.

While we have shown and described precise operating steps, it is to be understood that the drawings and descriptive matter are to be interpreted in an illustrative rather than a limiting sense, since various modifications may be made within the scope of the appended claims.