US1486365A - Forging process - Google Patents

Description

J. C. CUMMINGS FORGING PROCESS Filed Nov. 30 1920 Patented Mar. lll, T1924.

UNHTE STATS JOSEPH C. CUMMINGS, 0F DETROIT, MICHIGAN.

FOJRGING PROCESS.

Application filed November 30, 1920. Serial No. 427,276.

To all whom it may concern.

Be it known that I, JosnPH C. CUMMINGS, a citizen of the United States, and resident of Detroit, in the county of l/Vayne and State of Michigan, have invented certain new and useful Improvements in Forging Processes, of which the following is a specification.

My present invention relates to the manufacture of tools and other articles from what is known in the art as high-speed steel, this term defining metal having tungsten, vanadium and chromium or other ingredients having similar properities. The better qualities of high-speed steel may contain up to say, 17% to 19% tungsten; 3 1/2% to l 1 4% chromium, 1% to 1 1/2% of vanadium, and say 1/3% to 3/4% of carbon.

The invention is concerned with an improved process having certain broad features in common with that of Patent to James 1. Waters No. 1,345,045, granted June 29, 1920, and is further concerned with the product of such improved process. The process may be employed to produce articles of any shape but has its preferred application to the making of flat articles, that is, to articles having small thickness compared to the face dimensions, and more specifically to disks to be machined into milling cutters and the like.

According to one feature of the invention, the metal of the ingot or casting is worked down transversely 1n the usual manner into a billet, thereby increasing the tensile strength by the formation of a grain or fiber longitudinally of the billet. The working is, however, carried on to an extent to form a billet of a cross-section materially smaller than that of the plan or face area of the articles to be formed, and blanks of appropriate volume severed from the end of the billet are forged to the shape desired with the grain extending parallel to the face of the articles to be produced.

I prefer to carry out my process by cutting off a length of billet of appropriate volume from stock of any gauge preferably materially smaller than that of the face of the articles to be formed and to forge said piece of metal in a mould of the face dimensions of said article by operation upon surfaces extending parallel to the grain of the metal, that is. upon surfaces that were part of the surface of the billet from which the piece was severed until the said piece is reduced to a blank of the thickness of the article to be made, and of the shape of the mould.

In the preferred specific application of my process to the production of high-speed steel disks, I employ billets of a cross-sec tion much smaller than the face area of the disks to be made, said billets being pref erably rectangular or square in cross-section. A piece being cut off the end of the billet of a volume substantially equal to that of the disk to be formed, this piece is reduced to a blank of the thickness of the disk by a forging operation upon surfaces that were part of the surface of the billet from which the piece was severed. This operation is preferably completed in a mould having a circular periphery to limit the spreading of the metal as it is flattened thereby producing the disk desired.

The execution of my process results in a novel and superior product embraced in the scope of my invention. A characteristic, particularly of fiat articles produced by my process, is that the grain of the metal has not only been greatly compacted by the forging, but it extends in a direction paral lel to the face of the article, that is, in the direction of the greatest dimension, rather than through the thickness, with advantages which will appear fully below.

In carrying out the invention, the successive workings are preferably performed at substantially the preferred temperatures set forth in the patent above referred to.

My invention as above noted is applicable to the manufacture of any articles from high-speed steel, but I shall specifically describe the process of forming a milling cutter, as shown in the accompanying drawings, in which Fig. 1 is a perspective view, shown broken ofi, of the ingot,

Fig. 2 is an end view thereof,

Fig. 3 is a view similar to Fig. 1 of the billet to which the ingot is worked down,

Fig. 4 is an end view of Fig. 3,

Fig. 5 is a view of the disk to be formed,

Fig. 6 is a view in transverse section of the refashioned disk; and,

Fig. 7 is a plan view indicating the manner in which the refashioned disk may be sheared or trimmed to form the cutter.

The direction of the grain or fiber of the steel is roughly shown in Figs. 1 and 3.

The ingot'shown in Figs. 1 and 2 is first reduced in cross-section by working according to the usual method to form a billet of the dimensions indicated in Figs. 3 and 4, and preferably rectangular in cross-section, as shown, the billet being of considerably smaller cross-section than the face area of the disk articles to be made therefrom, and shown in Fig. 6. A length of billet P is then sawed ofl' alongthe line AA indicated in Fig. 3, preferably a little greater in mass and volume than the disk into which it is to be converted to allow an excess for flash and scale losses. The parallelopipedonal piece P is now subjected to a hot forging operation upon a lateral surface B, O, D or E that is, an original surface of the billet from which the piece was severed, and which therefore extends parallel with the grain or fiber of the metal. In this forging operation the metal is reduced in thickness and correspondingly increased in face dimension, the corners being preferably worked into a generally circular outline somewhat as indicated in Figure 5.

The disk is then refashioned, preferably in a die, to the form shown in Fig. 6 and annealed rior to shearing or trimming to the final orm of cutter shown in Fig. 7.

In working the stock with the grain extending parallel to the face of the flat article to be made in the manner set forth, the forging operation tends to compact the grain of the stock, that is, it tends to cause the grain to come close together in a manner which will be exemplified hereinafter. This is particularly so where the stock is reduced by forging, as set forth, to the relatively small thickness of the articles to be made. By this compacting process, carbides, tungstides and other compounds in the steel are effectively broken up and spread throughout the mass of the blank, thus producing substantially uniform distribution and strength. Micrographs of a blank thus produced are substantially identical in appearance, whether taken near the center or near. the periphery of the blank, longitudinally or transversely thereof.

Where the smallest dimension of the ar: ticle is not produced by direct compacting of the grain or fiber of the metal in the manner described, as, for instance, where the billets are merely rolled to the diameter of the disks which are then machined to cutter form, the working does not penetrate to sufficient depth to effect uniform strength. Micrographs taken transversely near the center of such billets show a much coarser and less uniform grain than near the periphery and micrographs taken longitudinally of the billet also show a materially coarser grain than those taken transversely thereof. This difference in structure increases proportionally as the size of the billet increases. Gutters produced by this messes method are, therefore, subject to fracture, and this is particularly true of cutters of more than three inches in diameter.

Moreover, in the case of a cutter machined from a billet of. the cutter diameter, the grain extends axially of the cutter or through the thickness thereof. In such cases, it is substantially only the cohesive force between the short grain or fibers which resists peeling or breaking of the teeth, so

finished cutter the grain, therefore, extends substantially longitudinally of many of the teeth, whereby the great tensile strength of the steel fiber comes into play to resist the great stresses against the teeth occurring in operation. Thus, the losses of time and money due to fracture of cutters and to peeling or breaking of teeth are substantially eliminated by my invention. It is also found that a keener and more accurate cutting edge can be maintained where the disk is formed by my method, than where the grain extends through the thickness thereof.

To further point out the beneficial results to be attained by my method, a specific numerical illustration will be given. Let it be assumed that disks 5 1/8 inches in diameter and 3/4 inch in thickness are to be made according to my invention. Starting with an ingot (Fig. 1) say 8 inches square or 64 square inches in cross-section, the same would be reduced by preference to square stock (Fig. 3) 2 1/4 inch square or 5.0625 square inches. A length of billet P of 3 inches would have a volume slightly greater than that of the disk to be produced, the excess being allowance for flash and scale. After this length of billet is forged into disk form by my method, as set forth, the largest section transversely of the grain will be a diametrical section through the disk and this area will be 5 1/8x3/4 inches or 3.84 square inches. The maximum cross-section of the disk in Fig. 5 is, therefore 3.84/64 of that of the original ingot, and the cross-section of the ingot has thus been worked down and compacted to an area only 6% as great. The metal along the various sections of the disk parallel to the diametrical section is obviously compacted to an even greater extent so that the entire length of the grain is effectively compacted.

Lesaeec Where a disk of the same dimensions, that is, 5 1/8 inches in diameter and 3/4 inch in thickness is made by machining methods from a round bar of approximately the same diameter as the disk it is necessary to start with a much larger ingot, say twelve inches square or 144 square inches in crosssection; The cross-section of the round 5 1/4 inch bar produced therefrom is 20.629

square inches, or say 14.4% of that of the ingot. The 5 1/8 disk is then cut off and machined Without any further forging, whereas by my method as above shown the crosssectional area of the ingot was worked down to a materially greater extent, that is, to 6% of its original area and then further finishforging which is particularly effective at the edges. Thus by my invention, the fibers have been compacted considerably more than twice as much as by the other method, although I start with a much smaller ingot. By this greater compacting of the grain, the product is not only rendered more uniform, but the tensile strength transversely of the grain or the cohesion between the fibers is multiplied.

Hence a cutter produced by my method is far superior to one produced by other methods, firstly, because the metal has been worked to such extent that there are no weak spots at which fracture can take place, secondly, because the grain extends length wise of a considerable number of the teeth and the great tensile strength of the metal in the direction of the grain operates to resist rupture of the teeth, and thirdly,-because the grain or fiber has been compacted to such an extent as to greatly increase the cohesive strength between the grain or fibers as compared with the product resulting from other methods.

To achieve the best results, with high speed steel,-the successive forging operations are performed substantially at the temperatures indicated in the Waters patent above referred to, that is, the blank cut from billet P is heated to a temperature around .1900 degrees F., or say between 1850 degrees and 1950 degrees, for forging to approximately desired thinness and circular shape, as indicated in Fig. 5, while the refashioning in the die to the form shown in Fig. 6 would preferably be at a lower temperature, around 1800 degrees F. or say between 17 50 degrees and 1850 degrees.

I claim:

1. The process of forming articles from high-speed tungsten steel of the class de scribed, which process includes working the cross-section of the metal of a billet to a thickness substantially that of the article to be made, and a width no greater than the maximum dimension of said article and exerting pressure substantially at right angles to the face of said metal of reduced thickness and at right angles to the grain of said metal to produce the finished article.

2. The process of forming articles from high-speed tungsten steel of the class described, which process includes working the cross-sectional area of the metal of an ingot to reduce it to a cross-section rectangularin form and smaller than the largest sectional area of the articles to be made, severing lengths of appropriate volume and fashioning said lengths into the articles desired by a forging operation solely upon surfaces of the metal extending along the grain thereof.

3. The process of forging high-speed tungsten steel of the class described, which process includes severing from the end of a billet a piece of appropriate volume but of dimensions different from those of the finished article, and fashioning said piece to the desired thickness by operating solely upon surfaces thereof extending in the direction of the grain.

4. The process of forming articles from high-speed tungsten steel of the class described, which process includes severing from the end of a billet, a piece of the appropriate volume, but of dimensions different from those of the finished article and fashioning said piece by performing a. flattening operation in a mold upon a surface of the piece that was part of the surface of the billet.

5. The rocess of formingarticles from high-speed tungsten steel of the class described, which process includes severing from the end of a billet a piece of appropriate volume but of dimensions different from those of the' finished article, and flattening said piece in an appropriate mold by operation upon a Surface that was part of the surface of the billet, to a thickness substantially equal to one dimension of the article and then performing a shaping operation in a die.

6. The rocess of forming fiat articles of substantia ly uniform dimensions from high-speed tungsten steel billets of a crosssection materially smaller than the plan area of said articles, which process consists in severing from the end of the billet a piece of appropriate volume, operating in an appropriate mold upon that portion of the surface of the piece that was part of the surface of the billet, to reduce the thickness thereof to that of the article while the mold limits the spread of the metal, thereby producing the contour desired.

7. The process of forming disks of substantially uniform dimensions from highspeed tungsten steel billets of a rectangular cross-section materially smaller than the plan area of the disks, which process consists in severing from the end of the billet a piece of appropriate Volume, forging in an appropriate disk shaped mold at that portion of the surface of the piece that was part of the surface of the billet, to reduce the thickness to substantially that of the disk to be formed, while the mold limits the spread of the metal, thereby producing the contour desired.

8. In a process of forming articles from blanks of high-speed steel, the step of forging the metal by operation upon surfaces of the blank that were part of the surface of the billet from which it is severed, said operation being performed at temperatures high enough for malleability but less than 2000 F.

9. llhe process set forth in claim 2, in which the forging operation is performed aeeaeee at a temperature between 1850 degrees and 1950 degrees F. a 4

10. The rocess set forth in claim 5 in which the attening operation is performed at a temperature of approximately 1900 F, and in which the shaping operation is performed at a lower temperature.

ture between 1750 degrees and 1850 degrees F.

Signed at Ann Arbor, in the county of Washtenaw and State of Michigan, this 26th day of November, A. D. 1920.

JOSEPH C. CUMMINGS.

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