US3456474A - Forging method and apparatus - Google Patents

Description

July 22, 1969 H. MCCLELLAN ET AL 3,456,474

FORGING METHOD AND APPARATUS Filed Sept. 28, 1967 2 Sheets-Sheet l INVENTORS z/zeaeer A. MZZ 6.4 4,4, zoo/V410 a. #0:: BY

July 22, 1969 MCCLELLAN ET AL 3,456,474

FORGING METHOD AND APPARATUS Filed Sept. 28, 1967 2 SheetsSheet 2 INVENTORS #5195522 4. MCZAZZAM 004/440 6. H055 I;

A TTOA/E/S United States Patent 3,456,474 FORGING METHOD AND APPARATUS Herbert L. McClellan and Donald E. Hnss, Tilfin, Ohio, assignors to The National Machinery Company, Tiffin, Ohio, a corporation of Ohio Filed Sept. 28, 1967, Ser. No. 671,384

Int. Cl. 1521b 1/00 US. Cl. 72203 21 Claims ABSTRACT OF THE DISCLOSURE Field of invention This invention relates to a method and apparatus for cold forming stock by applying deforming forces thereto and more particularly to a novel and improved method and apparatus for shaping elongated substantially circular cross-section stock including at least one operation wherein such stock is roll formed to a polygonal shape.

This invention, in one of its broader aspects, provides a novel and improved method and apparatus for cold rolling rod or wire stock of circular cross-section to a polygonal shape in a single pass through a single pair of forming rolls. In another of its broader aspects this invention provides a novel and improved forging machine in which elongated stock is first rolled to a polygonal shape by the machine feed rolls and is subsequently sheared into blanks which are further worked by cooperating tools and dies.

Prior art In the past the rolling of elongated stock to produce polygonal shaped stock, such as hexagonal cross-section stock, has generally required the use of a plurality of pairs of rolls which operate to shape the stock to the desired cross-section. In most instances the pairs of rolls operate sequentially to produce the desired shape. Such arrangements require either multiple passes of the stock or require the use of complex machines.

In the past it has also been known to shape rod or wire stock into a polygonal shape, such as a hexagonal shape, before the stock feeds into an automatic forging machine in which the stock is cut into blanks and the blanks are upset to desired shapes. Examples of such machine with preliminary forming are illustrated in the United States Letters Patent No. 3,178,924 dated Apr. 20, 1965, and No. 2,689,360 dated Sept. 21, 1954.

In machines of this type stock is formed to a polygonal shape by a sepaarte subassembly which usually works and shapes the stock before it reaches the machine feed rolls. The feed rolls then operate to feed the stock into the shear of the machine which cuts blanks of measured length from the end of the stock. The blanks are then worked in one or more die stations to the desired shape.

The preliminary forming of stock to a polygonal shape is often desirable in the manufacture of blanks for various articles, such as nuts and the like, since it reduces the amount of forming required in the die stations. Consequently less complex dies and lower working pressures can often be used to form a given blank. Also, such machines can sometimes be used to manufacture articles 3,456,474 Patented July 22, 1969 from lower quality stock since flaws or imperfections in the stock are not enlarged as much when at least part of the shaping of the stock is performed by radially inward material flow rather than by radially outward flow.

Summary of invention In one of its broad aspects, this invention provides a novel and improved method and apparatus for roll forming elongated stock. In the illustrated embodiment round rod or wire stock is passed through a single pair of rolls and is shaped thereby to a regular hexagonal cross-section having relatively sharp corners.

Each of the rolls is formed with a shaping groove in its periphery which cooperates with the groove of the other roll to define a polygonal opening, a regular hexagon in the illustrated embodiment, through which the stock passes. The grooves are sized and arranged so that an opposed pair of corners of the hexagonal opening are located at the adjacent peripheries of the rolls and so that the acrossthe-corners dimension of the opening, and of the shaped stock, is no greater than the initial diameter of the stock.

In the illustrated embodiment the across-the-corners dimension is less than the initial diameter of the stock and yet there is no flash produced. The absence of flash and the accuracy of the hexagonal shape imparted to the stock by the rolls are both surprising and unexpected results. Generally, when stock is formed between a pair of rolls there is an increase in the lateral dimension of the stock in a plane lengthwise of the stock parallel to the axes of rotation of the rolls. Such an increase in lateral dimension produces severe problems of flash when the throat through which the stock must pass has a lateral dimension equal to or less than the corresponding initial lateral dimension of the stock. Consequently, in the past, person skilled in the art have utilized a plurality of pairs of rolls and/ or successive passes to deform circular cross-section stock to a polygonal shape.

We have discovered, however, that round stock can be deformed by a single pair of forming rolls in a single pass of the stock to a polygonal shape in which the across-thecorners dimension at the adjacent peripheries of the rolls is equal to or less than the initial diameter of the stock without encountering such flash. In fact, when the acrossthe-corners dimension at the adjacent peripheries of the rolls is less than the initial diameter of the stock it has been discovered that the surface portions of the stock aligned with such corners move inwardly toward each other as the stock enters the throat of the rolls before such portions are even contacted by the surface of the rolls. Consequently, the edges on the rolls at the junction between the peripheries and the adjacent walls of the grooves do not engage the stock as they approach each other and consequently do not shear away portions of the stock which would result in flash.

We have also discovered that the preliminary forming of stock, feeding into an automatic forging machine, can be provided by the machine feed rolls. In such machines the feed rolls provide both the shaping and the feeding functions. Consequently, with a forging machine incorporating this invention, the intermittently driven feed rolls normally provided on such machines to feed the stock into the shear of the machine are used to perform a preliminary shaping operation on the stock, It is, therefore, possible with a machine incorporating this invention to achieve the preliminary forming of the stock without the use of auxiliary subassemblies and without increasing the complexity of the machine.

Objects of invention It is an important object of this invention to provide a novel and improved method and apparatus for roll forming rod or wire stock of circular cross-section to a polygonal cross-section in a single pass through a single pair of forming rolls.

It is another important object of this invention to provide a novel and improved forging machine in which a single pair of forming rolls operates to deform rod or wire stock to a polygonal shape and also operates to feed the stock into the shear of the machine.

Further objects and advantages will appear from the following description and drawings, wherein:

FIGURE 1 is a schematic, fragmentary, plan view of a forging machine incorporating this invention;

FIGURE 2 is a fragmentary side elevation of the machine illustrated in FIGURE 1 showing one type of drive linkage which may be used to intermittently rotate the forming feed rolls of the machine;

FIGURE 3 is a schematic perspective view illustrating the forming feed rolls and their relationship to the shear which shears measured blanks from the end of the preformed stock;

FIGURE 4 is an enlarged fragmentary side elevation of the feed rolls in the area of the throat illustrating the shaping operation performed on the stock as it passes through the rolls;

FIGURE 5 is an enlarged fragmentary section, taken along 5-5 of FIGURE 4, illustrating the throat of the forming feed rolls and illustrating the initial diameter of the stock as it enters the feed rolls;

FIGURE 6 is an enlarged plan view of a piece of stock shaped by the forming rolls of FIGURES 4 and 5 illustrating the transition zone in which the stock is deformed from a circular section to a hexagonal section; and

FIGURE 7 is a fragmentary side elevation of the piece of stock illustrated in FIGURE 6.

FIGURES 1 and 2 provide a schematic illustration of a representative type of forging machine which is operable to shear blanks of measured length from elongated rod or wire stock 10 and subsequently shape the blank to a desired shape with cooperating tools and dies. Such machines may include one or more die stations and may be of the type which performs one or more working operations at each die station.

The illustrated machine includes a frame 11 having a reciprocating slide 12 supported thereon. Tools 13 through 15 are mounted on the slide 12 and cooperate with frame mounted dies 16 through 18, respectively, to progressively form a blank to a desired shape. Automatic transfer means (not illustrated) are provided to progressively transfer the blanks from one die to the next.

It should be understood that the machine illustrated in the drawings is shown only as a representative machine and that this invention may be applied to other forms of machines, such as double blow machines or progressive forming machines having greater or lesser num bers of die stations.

A feed box 19 is mounted on the frame 11 and a pair of feed rolls 21 are journaled thereon to engage opposite sides of the stock 10 and feed the stock to a shear station 22 at which the blanks are cut from the end of the stock. The feed rolls are connected for counterrotation and are intermittently driven by a linkage of the type illustrated in FIGURE 2. This linkage includes an oscillating rocker arm 23 driven by a rotating crank 26 and a connecting rod 24. The oscillating movement of the rocker arm 23 is transmitted through a connecting rod 27, a crank 28, and a one way drive clutch 29 to the feed box. In the illustrated linkage the magnitude of oscillation of the crank 28 can be adjusted by moving and adjusting connection 31 along the rocker arm 23 toward or away from its pivot 32. This drive linkage for the feed rolls 21 is illustrated as a representative type often used on machines of this category. Such a linkage automatically times the operation of the feed rolls with the operation of the remaining portions of the machine, since the crank 26 is driven by the main machine drive.

Referring to FIGURE 3, the pair of feed rolls 21 includes an upper roll 33 mounted on a shaft 34 for intermittent rotation around the axis of the shaft 34 in a clockwise direction and a lower roll 36 mounted on a shaft 37 for intermittent rotation around the axis of the shaft 37 in an anticlockwise direction. The two rolls 33 and 36 are of the same size and the two shafts 34 and 37 are interconnected by drive means (not illustrated) for synchronized counterrotation by the linkage and clutch illustrated in FIGURE 2.

The stock 10 is engaged on opposite sides by the two rolls 33 and 36 and is fed by the rolls through a stationary cutter element 38 and a moveable cutter arm 39 until the end of the stock 10 engages a fixed stop 41. In the illustrated embodiment the stock 10 is rolled from a circular cross-section to a regular hexagonal cross-section as it passes through the rolls 33 and 36, so the cutter elements 38 and 39 are formed with hexagonal openings 42 and 43, respectively, which closely fit the stock as it enters the shear mechanism 22. The cutter arm 39 is pivoted at 44 and is provided with a cam follower 46 which rolls along a cam 47 powered by the main machine drive. The cam 47 is shaped to oscillate the cutter arm 39 from a first position in which its opening 43 is in alignment with the opening 42 and a second position in which its opening 43 is in alignment with a hexagonal opening 48 in the die 16.

The drive of the rolls 33 and 36 and the drive of the cam 47 are timed so that the cutter arm 39 is positioned as illustrated in FIGURE 3 before the rolls are rotated. The rolls are then rotated through an angle sufficiently great to move the end of the stock 10 into engagement with the stop 41. While the rolls 33 and 36 are stationary the cutter arm 39 then moves to a position in front of the die 16 causing a blank 49 to be sheared from the stock 10. The length of the blank 49 is equal to the distance between the shear plane between the shear elements 38 and 39 and the stop 41.

The arm 39 is held by the cam 47 in its position in front of the die 16 while the slide 12 carries the tool 13 forward. The tool 13 pushes the blank 49 out of the shear arm 39 pressing it into the die 16. In some machines the die 16 and the tool 13 are arranged to provide working of the blank and in other machines the die 16 serves only as a holding die from which the blank is transferred to the subsequent die station or stations. After the tool 13 is retracted by the slide 12 the shear arm 39 is returned to the illustrated position and the rolls again operate to feed additional stock into the shear. This cycle is repeated and measured blanks 49 are successively cut from the end of the stock.

Referring now to FIGURES 4 through 7, the two rolls 33 and 36 are formed with cylindrical peripheries 51 and 52, respectively. Centrally of the peripheries 51 and 52 the rolls 33 and 36 are formed with shaped grooves 53 and 54, respectively. In the illustrated embodiment these grooves 53 and 54 are identical to each other in shape and size and cooperate with each other to define a hexagonal opening 56 at the throat illustrated in FIGURE 5. Each of the grooves 53 and 54 provides opposed conical walls 57 and 58 converging from edges 59 and 61, respectively, at the peripheries of the rolls. Consequently, the hexagonal opening 56 is provided with opposed corners at 59 and 61 at the adjacent peripheries of the rolls. The grooves 53 and 54 are completed by cylindrical surfaces 62 which join the associated opposed surfaces 57 and 58 and cooperate therewith to define the other four corners of the hexagonal opening 56'.

The stock 10 initially has a circular cross-section illustrated by the dotted circle 63 and after passing through the rolls 33 and 36 has a regular hexagonal cross-section as illustrated at 64 which is substantially identical in shape and size to the regular hexagonal opening 56. When the across-the-corners dimension C of the hexagonal stock 64 is at least as small as the initial diameter D, the corners of the hexagonal portion 64 are relatively sharp. Even sharper corners are formed with the across-thecorners dimension C is slightly less than the initial diameter D of the stock.

' In one successful rolling operation stock having an initial diameter D of .411 inch was rolled between rolls having a inch diameter to a regular hexagonal shape in which the across-the-corners dimension C of the hexagonal rolled portion of the stock was .397 inch. This was accomplished without producing flash even though the corners at 59 and 61 were spaced apart by a distance less than the initial diameter of the stock.

In another successful rolling operation circular crosssection stock having an initial diameter D of .811 inch was rolled between 10 inch diameter rolls to produce hexagonal stock having an across-the-corners dimension at the periphery of the rolls of .781 inch. Here again this rolling was achieved without flash even though the spacing between the edges at 59 and 61 was less than the initial diameter of the stock.

It was found that the transition section of the stock appeared as illustrated in FIGURES 6 and 7. The flats 66 and 67 were formed by the roll surfaces 57 and 58, respectively, and the flats 68 were formed by the roll surfaces 62. It should be noted that the inclined opposed surfaces 57 and 58 engage the stock before the cylindrical surfaces 62 at the points 69 before the surfaces 62 engage the stock at the points 71. Thus the working of the stock to form the flats 66 and 67 is initiated before the working of the stock to form the flats 68.

It was also found that the surface of the stock aligned with the throat corners defined by the edges 59 and 61 commenced to move laterally inward at a point located at about 72 even though this surface portion of the stock is not engaged by the rolls at that point. This inward movement continues without engagement between such stock surface and the surface of the rolls until the stock is substantially at the throat at 73. Consequently, the edges 59 and 61 on the two rolls do not engage the stock until the associated edges 59 and 61 are in substantial abutment at the throat and there is no shearing of surface material of the stock by the approach of these edges. Therefore, no flash is produced.

It is believed that this inward movement of the surface material in the zones aligned with the corners of the opening 56 is produced because the degree of reduction of the stock is sufiiciently great to cause the material forming the core of stock to tend to move faster axially than the material forming the surface of the stock thus placing the surface portions of the stock in tension. It is further believed the tension at the surface causes the surface material to constrict or move inwardly before such surface portions are engaged by the rolls. In any event there is an absence of the lateral widening of stock normally present when stock is reduced in cross-section by passing it through rolls, so it is possible to roll the stock to a polygonal shape wherein the spacing across the comers of the polygonal opening defined by the rolls is no greater than the initial diameter of the stock.

We prefer to mount the rolls 33 and 36 so that the peripheries 51 and 52 engage at the throat. When this arrangement is utilized the rolls themselves insure proper spacing and the polygonal opening 56 is accurately maintained in size by the bearing engagement of the roll peripheries immediately adjacent to the polygonal opening. Preferably the two shafts 34 and 37 are preloaded toward each other with suflicient force to overcome the rolling loads and insure peripheral contact between the rolls while stock is being rolled.

We also prefer to adjust the intermittent drive linkage illustrated in FIGURE 2 so that a slight overtravel is provided to insure firm contact between the end of the stock and the stop 41 so that the accuracy of blank length will be maintained. This requires a slight amount of slippage between the rolls and the stock since the stop 41 prevents movement of the stock with the rolls after the end of the stock engages the stop. This slight amount of slippage does not produce excessive wear nor does it provide buckling of the stock.

We also prefer to utilize rolls having a diameter sufficiently large when compared to the initial diameter of the stock to eliminate any need to push the stock when an end starts through the rolls. When such ratio is sufficiently large the approach angle at the initial points of engagement is sufficiently small so that the end of a piece of stock -will enter the rolls without requiring special apparatus to press the end of the stock into the rolls.

The frictional drive on the stock produced by the rolls is sufficiently gerat to pull the stock into the rolls from the stock supply, which may be in the form of straight rods or a coil, and through any straighteners required. The axial force is not of such a large magnitude that it produces difficulty when the rolls slip on the stock after the stock engages the stop 41.

Although a preferred embodiment of this invention is illustrated it is to be understood that vairous modifications and rearrangements of parts may be resorted to without departing from the scope of the invention disclosed and claimed herein.

We claim:

1. A rolling apparatus for cold roll forming polygonal cross-section stock from stock having a substantially circular cross-section of a predetermined diameter comprising a single pair of rolls journaled for counterrotation about spaced and parallel axes, the peripheries of said rolls being adjacent to each other at a throat in a plane containing said axes, said rolls each being formed with shaped peripheral grooves which cooperate to form a polygonal opening at said throat having opposed corners at the adjacent peripheries of said rolls, said opposed corners being spaced by a distance at least as small as said predetermined diameter, said grooves each providing opposed surfaces extending inwardly and converging from outer edges at the periphery of said rolls, said rolls reducing the cross-sectional area and elongating said stock as it passes between said rolls and forming said stock to substantially the shape of said polygonal opening without producing any substantial flash at said opposed corners.

2. A rolling apparatus as set forth in claim 1 wherein the maximum lateral dimension of said polygonal opening is less than said predetermined diameter.

3. A rolling apparatus as set forth in claim 2 wherein said grooves are sized and shaped so that the spacing between the surface of said stock aligned with said opposed corners is reduced as the stock approaches said throat before being contacted by said rolls at a rate sufliciently great to prevent contact between the surface of said stock and said outer edges of said opposed surfaces substantially before the stock enters said throat.

4. A rolling apparatus as set forth in claim 3 wherein the percentage of reduction of cross-sectional area of said stock as it passes through said rolls is sufficiently great to cause the core portion of said stock to elongate at a rate sufliciently great to place the peripheral portions of said stock in tension as the stock approaches said throat.

5. A rolling apparatus as set forth in claim 1 wherein the maximum lateral dimension of said polygonal opening is at least as small as said predetermined diameter.

6. A rolling apparatus as set forth in claim 5 wherein said grooves are similar in size and shape.

7. A rolling apparatus as set forth in claim 6 wherein said grooves define a regular polygonal opening having an even number of sides.

8. A rolling apparatus as set forth in claim 7 wherein said polygonal opening is hexagonal.

9. A rolling apparatus as set forth in claim 1 wherein said rolls are mounted so that they are urged toward each other with suflicient force to maintain their peripheries in engagement while stock passes therebetween.

10. A rolling apparatus as set forth in claim 1 in combination with a machine for upsetting blanks, said machine including a frame, a slide reciprocable on said frame, and a shear operable to out blanks from said stock after it is shaped by passing between said rolls, said frame and slide being adapted to support cooperating tools and dies for upsetting said blanks.

11. A rolling apparatus as set forth in claim 10 wherein drive means are provided to intermittently drive said rolls in timed relationship to the operation of said slide to simultaneously form said stock to a polygonal shape and feed said stock into said shear.

12. A rolling apparatus as set forth in claim 11 wherein said shear includes a stop, and said rolls feed the end of said stock into engagement with said stop after each blank is cut therefrom.

13. A rolling apparatus as set forth in claim 12wherein said drive means operate to continue to drive said rolls through a limited amount of rotation after the end of said stock engages said stop causing slippage between said rolls and said stock, said drive means being inoperative to drive said rolls while said shear is operating.

14. A rolling apparatus as set forth in claim 12 wherein the maximum lateral dimension of said polygonal opening is at least as small as said predetermined diameter.

15. A rolling apparatus as set forth in claim 12 wherein the maximum lateral dimension of said polygonal opening is less than said predetermined diameter.

16. A rolling apparatus as set forth in claim 15 wherein said grooves define a regular polygonal opening having an even number of sides.

17. A rolling apparatus as set forth in claim 16 wherein said polygonal opening is hexagonal.

18. A rolling apparatus as set forth in claim 16 wherein the ratio of the diameter of said rolls to said predetermined diameter is sufliciently great so that the end of a piece of stock is carried into and through said throat without separately applying any substantial axial force on said stock.

19. A methd of form rolling elongated stock in which elongated stock having a substantially circular crosssection is shaped to a polygonal cross-section by passing such stock through a single pair of forming rolls comprising engaging said stock with four opposed substantially conical surfaces with two on each roll and progressively deforming four peripherally spaced portions of said stock inwardly toward the central axis thereof until adjacent pairs of spaced portions are substantially joined at opposed corners spaced apart by a distance smaller than the initial diameter of said stock, the deformation rate and the reduction in cross-section being arrangedso that the surface portions of said stock aligned with said opposed corners move toward each other as the stock enters said rolls before said surface portions are engaged by surfaces of said rolls.

20. A method of form rolling as set forth in claim 19 wherein said stock is deformed inwardly toward its central axis at two additional locations with one located on each side of a plane through said opposed corners.

21. A method of form rolling as set forth in claim 20 wherein said deformation continues until said stock has a regular hexagonal cross-section with its lateral acrossthe-corners dimension less than the initial diameter of said stock.

References Cited UNITED STATES PATENTS Re. 5,121 10/ L872 Ostrander 72-203 882,321 3/1908 Jenks 72-187 1,987,324 1/1935 Catterall et al 72366 CHARLES W. LANHAM, Primary Examiner LOWELL A. LARSON, Assistant Examiner

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