US3310822A

US3310822A - Method and apparatus for making socket head screws

Info

Publication number: US3310822A
Application number: US364508A
Authority: US
Inventors: Herbert L Mcclellan; Donald E Huss
Original assignee: National Machinery Co
Current assignee: National Machinery Co
Priority date: 1964-05-04
Filing date: 1964-05-04
Publication date: 1967-03-28
Anticipated expiration: 1984-03-28
Also published as: DE1297571B

Description

March 28, 1967 H. MCCLELLAN ETAL 3,310,822

METHOD AND APPARATUS FOR MAKING SOCKET HEAD SCREWS Filed May 4, 1964 6 Sheets-Sheet 1 DONALD E- HUSS R I253, EN/VY [FE/NGTON ATTORNEYS March 28, 196? H. L. MCCLELLAN ETAL 3,310,822

METHOD AND APPARATUS FOR MAKING SOCKET HEAD SCREWS Filed May 4, 1.964 1 6 Sheets-Sheet 2 EN TORS HERBERT L-MCCLELLAN BY &DONALD 5. H055 March 28, 1%? H. L. MCCLELLAN ETAL METHOD AND APPARATUS FOR MAKING SOCKET HEAD SCREWS 6 Sheets-Sheet 3 Filed May 4, 1964 M SL r wa a 2% .MJ 3 d a 4 0 EL 7 E A x V D 3 EN 5 E so 5 B a d L W: 4 .s 3 a Q 4 N s w H m We M 1m m A N 6 Sheets-Sheet 4 Marsh 28, N67 H. L. MCCLELLAN ETAL METHOD AND APPARATUS FOR MAKING SOCKET HEAD SCREWS Filed May 4;, l964 arch 28, 1967 H. 1.. MCCLELLAN ETAL 3,319,822

METHOD AND APPARATUS FOR MAKING SOCKET HEAD SCREWS Filed May 4, 1964 6 Sheets-Sheet 5 INVENTORS HFEBEPTLNCCLELlA/V r DON/31D E-HUSS BY EICEKNI/V/VNY FAEE/A/G TOA/ March 28, 1%? H. L. MCCLELLAN ETAL 3,

METHOD AND APPARATUS FOR MAKING SOCKET HEAD SCREWS Filed May 4, 1964 e Sheets-Sheet e 1746961597 L. M ((614444 gum/4&0 6. H065 United States Patent 3,310,822 METHGD AND APPARATUS FOR MAKTNG SGKET HEAD SCREWS Herbert L. McClellan and Donald E. Huss, Tiffiu, Ohio,

assignors to The National Machinery (Company, Tifiin,

Ohio, a corporation of Gino Filed May 4, 1964, Ser. No. 364,598 13 Claims. (Cl. 1Q7) This invention relates generally to forging and more particularly to a novel and improved method and apparatus for cold forging articles having upset portions such as socket head cap screws and the like.

A method and apparatus incorporating this invention makes it possible to economically cold forge high quality socket head cap screw blanks in two working strokes on a blank contained within a single die. This invention therefore permits the manufacture of finished socket head cap screw blanks in a double blow header. To accomplished this result, the method and apparatus incorporating this invention utilizes a novel and improved upsetting operation during the first working stroke to produce an intermediate blank having an intermediate upset head which is thereafter socketed in a novel and improved manner to produce a finished socket head cap screw blank wherein the grain structure of the finished blank forms a pattern tending to conform to the shape of the blank. Such a grain pattern results in a high strength blank of superior quality.

By utilizing the method and apparatus incorporating this invention, it is possible to upset a portion of the blank within a single working stroke wherein the initial length of stock upset is long when compared to its initial di ameter without introducing reentrant folds, planes of weakness or undesirable fins. The method and apparatus incorporating this invention also permits the socketing of the intermediate head without tool breakage or blank ruptures which has produced difliculty in many prior methods of manufacture of such articles.

in the manufacture of articles having upset portions such as screw and bolt blanks, it has been found that difficulty occurs if upsetting is attempted in a single stroke wherein the initial length of stock upset is long when compared to the initial diameter, since the stock in such cases tends to buckle formin re-entrant folds in the finished article. It has been found that in a given process with a given material there is a critical ratio of initial unsupported length to initial diameter, which is exceeded will often cause buckling and result in re-entrant folds in the upset portion of the finished article. This critical ratio is not an absolute value for all blanks and all upsetting operations since the form of the tools and the type of support provided thereby affects the ratio. Also irregularities in the blanks and the surface of their ends will change the ratio. As a general proposition, the critical ratio is that ratio below which blanks can be upset in a given type operation while producing uniformly good quality upsets.

In many articles including many types of standard bolts, the volume of material required to form the head, when compared to the shank diameter, requires the upsetting of a length of stock exceeding this critical ratio. To manufacture such articles, it has been customary in the past to overcome the buckling problem by performing the required upsetting in a series of blows which progressively gather the stock by increasing its diameter and reducing its length. In such manufacture the first upsetting blow is often referred to as coming during which the stock is gathered to increase its diameter and shorten its length. On subsequent blows, which may include one or more upsetting strokes, the stock is further upset to form the required article. This procedure of eliminating re-entrant folds by using multiple upsets complicates the machines "ice structure required to produce a given article. However, in spite of its disadvantages it has been used extensively since it has offered one of the best solutions to the basic problem.

Another method of eliminating the re-entrant fold problem has sometimes been used when upsetting blanks requiring upset volumes exceeding the critical ratio. In this method of sliding cone tool or sleeve is positioned around the end of the blank against the die formed with the cavity to receive the upset. An upsetting tool is then pressed along the coming tool pushing the laterally confined end of the blank therefrom into the cavity thereby forming the upset. This method while providing a solution to the bending problem introduces two principal difiiculties. The

rst difficulty results from the production of a fin on the end of the blank which cannot be tolerated in many articles. This fin is formed at the junction between the upsetting tool and the inner surface of the sliding cone tool. As the upset progresses the end of the blank swells into tight frictional engagement with the inner surface of the coning tool producing extremely high pressures adjacent to the upsetting tool face. These high pressures and the drag of the material along the coning tool surface causes a fin to be formed in the clearance between the moving tool elements.

The second difficulty occurring with such method of making upsets is caused by the formation of an area of scrambled grain flow very close to the junction of the upset portion of the blank and the portion which is not upset. When manufacturing bolt blanks this area of scrambled grain flow occurs at the junction between the head and shank of the blank and produces a plane of weakness in the very location where the blank must have high strength.

in a machine incorporating the present invention, it is possible to greatly increase the amount of upsetting accomplished in a single blow or working stroke of a heading machine without creating re-entrant folds, planes of weakness or unacceptable fins. This is accomplished by arranging the upsetting tool so that the unsupported length of stock in maintained below the critical ratio while still accomplishing an upset of material which has a length to diameter ratio exceeding the critical ratio. During a single upsetting blow, two different sequential modes of operation are performed. During the first .portion of the upsetting stroke, a portion of the blank is surrounded and supported by a stationary coning tool sleeve and an upset tool moves through the sleeve performing a gathering or partial upsetting operation.

Since the stock is supported bythe sleeve, the unsupported length during this first phase of operation is maintained below the critical ratio and buckling does not occur. Sulficient clearance is provided between the end of the blank and the inner walls of the sleeve to permit some upsetting of the end of the blank without producing tight engagement between the material forming the end of the blank and the wall of the sleeve. Therefore, excessive pressures are not developed immediately adjacent to the clearance between the upsetting tool and the sleeve and fins do not occur. The initial clearance between the blank and the walls of the sleeve, however, is such that any tendency of the blank to bend brings the blank into lateral engagement with the portion of the inner wall of the sleeve in the direction of the bend, thus providing lateral support to eliminate sufficient bending to cause re-entrant folds.

During the second phase of operation, the sleeve and the upsetting tool move as a unit continuing the upsetting operation. Since the unsupported length is less than the critical ratio at all times, the problem of buckling is completely eliminated even though the amount of stock '3 0.3 upset has a length to diameter ratio initially exceeding the critical ratio.

During the final upsetting movement of the tool and sleeve as a unit, the upset portion engages both the end of the tool and the end of the sleeve, thus providing an upsetting area greater than the area of: the central tool. Since the area of upsetting is greater with a method and apparatus incorporating this invention the pressure distribution adjacent to the opposite endof the upset is relatively uniform and the scrambled grain flow does not occur at the junction between the upset portion of the blank and the portions of the blank which are not upset. Therefore, the plane of Weakness which occured with the past sliding cone tool method of manufacture are eliminated.

The result of an upsetting operation incorporating this invent-ion is to combine within a single upsetting stroke, without producing article imperfections, the operations which heretofore, in most cases, were per-formed by two or more sequential working strokes. This has the advantage of reducing the complexity of the machine performing the operation by reducing the number of working strokes which must be performed on a given blank. When this invention is utilized in a progressive header, the number of work stations required for a given article can thus be reduced. Also when the invention is used in a multiple blow header, such as a double blow header, it is possible to manufacture articles which have heretofore required three working strokes on each article even though the machine has a cycle having only two working strokes. Still further, when the invention is incorporated into a single stroke heading machine, it is possible to manufacture articles which heretofore have required the use of multiple working stroke machines such as progressive headers or double blow headers.

The upsetting operation incorporating this invention provides a continuous flow of metal. This produces an advantage since plastic flow is maintained easier than it is initiated or rte-established once it stops. Therefore, the use of sequential working strokes to accomplish a given degree of upsetting requires the initiation of plastic fiow each time the blow or upsetting stroke occurs. In this invention the number of times that plastic flow must be established is reduced so the tool wear and work required to achieve a given degree of upset is reduced.

The intermediate blank formed in the manner thus far described includes a head wherein the zone of engagement between the head and the axial wall of the die cavity is closer to the face of the die than to the inner end of the die cavity. Therefore, the head of the intermediate blank for-med during the first working stroke is not symmetrical about its mid-plane but rather is filled out more at the end remote from the shank than at its end adjacent to the shank. During the second working stroke, the intermediate head is socketed by pressing a hexagonal cross-section tool into intermediate head while the head is confined in the cylindrical die cavity. When this is done according to this invention, a well filled socketed head is formed wherein the grain lines of cold working tend to follow the shape of the finished article and a high strength blank is produced.

During the second working stroke, the portions of the head adjacent the upper end are backward extruded and the portions adjacent the shank are displaced until the head fills the lower corners of the die cavity. The backward extrusion of the portion of the head remote from the shank results in grain flow lines in the material which extend substantially parallel to both the inner socket walls and the exterior cylindrical wall. The head material in the area adjacent the shank, however, is not backward extruded but rather forged by both upsetting and displacement plastic flow and results in a grain structure having flow lines tending to smoothly conform to the transition shape of the article.

If the upset portion formed during the first upsetting stroke had completely filled the die cavity before the extruding operation the extrusion punch coming into the upset would immediately cause the metal to how backward along the punch. As the punch advanced near the end of its stroke the only material the punch could affect would be the material ahead of its end nose which would be the material immediately adjacent to the underside of the head. This material would have to backward extrude along the punch and would drag outwardly and along the punch the material forming the underside of the head. This would produce an unfilled peripheral corner adjacent to the lower end of the blank in the finished device. By utilizing the preferred form of this invention this difiiculty is eliminated and the corners of the blank are properly filled. Also, the pressures on the punch are substantially lower since it is not necessary to backward extrude the material as the punch reaches a zone close to the inner end of the upset.

It is an important object of this invention to provide a novel and improved method and apparatus for forming socket headed screw blanks in two working strokes on the blank.

It is another object of this invention to provide a novel and improved upsetting tool structure having a first mode of operation during a first portion of the working stroke and a different mode of operation during the remaining portions of the working stroke.

It is still another object of this invention to provide a novel and improved method for upsetting stock wherein the unsupported length of stock is less than the initial length of the stock being upset.

It is still another object of this invention to provide a novel and improved method and apparatus for supporting stock during a portion of the upsetting thereof to prevent buckling and the like without forming fins or scrambled grain flow.

It is still another object of this invention to provide a novel and improved upsetting tool combination wherein a sleeve is positioned around a portion of the blank being upset to laterally support such portion and a tool is moved along the sleeve pressing such portion out of the sleeve and thereafter the tool and sleeve move as a unit continuing the upsetting thereby upsetting the blank without producing buckling, re-entrant folds or objectionable fins.

It is still another object of this invention to provide a novel and improved method and apparatus for forming socket head cap screws and the like wherein the portion of the head remote from the shank is backward extruded and thereafter the portion of the head adjacent the shank is displaced forward and laterally during the socketing operation.

It is still another object of this invention to provide a novel and improved socketing tool and die wherein the portion of a blank to be socketed engages the die wall at a zone intermediate its ends providing friction to resist upsetting and cause extrusion during the first phase of socketing and thereafter resist extrusion and cause upsetting during the second phase of socket-lug.

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

FIGURE 1 is a plan view of a double blow header incorporating this invention with parts removed for purposes of illustration;

FIGURE 2 is an enlarged fragmentary view of the structure of the dies and tools illustrating the position of the elements at the completion of the first working stroke of the double blow header;

FIGURE 3 is a fragmentary view with parts removed for purposes of illustration showing the position of the elements at the instant the upsetting operation of the first working stroke commences;

FIGURE 4 is a view similar to FIGURE 3 illustrating the position of the elements at the completion of the first phase of operation and the commencement of the second phase of operation during the first upsetting stroke;

FIGURE 5 is a view similar to FIGURES 3 and 4 illustrating the position of the elements at the completion of the first working stroke;

FIGURE 6 is an enlarged fragmentary section of the dies and tools at the completion of the first working stroke;

FIGURE 7 is a section through the die and tools illustrating the position of the elements at the completion of the second working stroke of the apparatus;

FIGURE 8 is a fragmentary View with parts removed for purposes of illustration showing the position of the elements immediately before the commencement of the blank working operation of the second Working stroke;

FIGURE 9 is a fragmentary view similar to FIGURE 8 at the completion of the second working stroke when the finished socket head cap screw blank is formed;

FIGURE 10 is a fragmentary section similar to FIG- URES 8 and 9 illustrating the position of the elements after the socketing tool is removed from the finished blank;

FIGURE 11 is an enlarged fragmentary section of a modified form of this invention wherein a shallow recess is formed in the head upset during the first working stroke of the machine;

FIGURE 12 is an end view of the head and socket formed by the embodiment of this invention of FIG- URE 11;

FIGURE 13 is a fragmentary section taken along 13 13 of FIGURE 12; and

FIGURE 14 is 'a fragmentary section of another modified form of this invention utilized to form blanks having shanks which are not threaded to the head A preferred embodiment of this invention is illustrated in conjunction with the manufacture of socket head cap screws in a double blow header. In FIGURE 1, a double blow header is illustrated including a frame 10 having a die breast 11 which in turn supports a die assembly 12. A header slide 13 is supported on the frame for reciprocating movement toward and away from the die breast 11 and is driven by the usual connecting rod 14 and crank 16. The crank 16 carries a fly wheel and is power driven by a V-belt arranged in the manner known in the art. A tool carrier 17 is pivoted on the header slide 13 and supports a tool holder 18 in which the two tool assemblies are mounted.

Essential parts of the machine are driven at half crankshaft speed in the illustrated embodiment of this invention. To this end there is a driving pinion 21 keyed to the crankshaft 16 which meshes with a half speed gear 22 keyed to a cross shaft 23. The cross shaft 23' carries a bevel gear 24 that meshes with a complementary gear 26 keyed to a longitudinally extending half speed assessory and cam shaft 27. The half speed shaft 27 operates the feed, sheartransfer, and knockout mechanism as well as the drive means for shifting the tool carrier between its two alternate work positions. The drive mechanism for shifting the tool carrier 17 is not illustrated, however, reference may be made to the United States Patent of Robert G. Friedman, No. 3,031,698, issued May 1, 1962, for a detailed description of such a drive mechanism.

Wire stock 32 is fed into the machine at a shearing station 33 until it engages an adjustable stock gauge (not shown). The shear and transfer assembly (not shown) then operates to shear a measured blank 34 from the wire 32 and moves the blank through an intermediate transfer station 36 to the die assembly 12. For a detailed description of the structure and operation of the shear and transfer mechanism, reference should be made to the United States patent of Robert G. Friedman, No. 3,116,499, issued Jan. 7, 1964. This mechanism is powered by the half speed shaft 27 and operates to position a blank 34 at the die assembly 12 on alternate strokes of the header slide 13. Thus, a new blank is positioned for upsetting in a timed manner with each cycle of the machine. The blank is then worked on two sequential working strokes by two different tool assemblies.

FIGURE 2 illustrates the structure of the tools mounted on the tool holder 18 and the structure of the die assembly 12. The die assembly 12 includes a forward die plate 41 formed with a central bore 42 having a diameter equal to the diameter of the finished head of the cap screw blank. The wall of the bore 42 provides the side wall of the heading die cavity. Positioned behind the forward die plate 41 is a second die element 43 having a central bore 44 coaxial with the bore 42 of a diameter equal to the diameter of the shank of the finished blank. The forward end of the bore 44 is flared at 46 to form a chamfer on the blank at the junction between the head and the shank. The two die

elements

41 and 43 are mounted in a ring 47 which is in turn mounted in the die breast 11. A knockout pin 48 extends into the rearward end of the bore 44 and is adjustably positioned therein to engage the blank 34 when the blank extends the desired distance into the bore 34. The usual power operated mechanism is connected to the knockout pin 4-8 to move the pin forward after the completion of the second working stroke to eject the finished blank from the die assembly 12.

The first working stroke tools on the die holder 18 include an upsetting tool 49 mounted on the tool holder 18 by

backup elements

51 and 52 so that the tool 49 is fixed relative to the tool holder 18. Positioned around the tool 49 is a sleeve 53, the forward end of which is formed with a bore 54 slid-ably engaging the forward end of the tool 49. The rearward end of the sleeve 53 extends into a guide 56 mounted in the tool holder 18 and is laterally supported thereby. The sleeve 53 is formed with an enlarged bore 57 around the midsection of the tool 49. A spring 58 in the bore 57 extends between the backup element 51 and a radial shoulder 59 on the sleeve 53 to resiliently urge the sleeve forward relative to the tool holder 18. The sleeve is also formed with a keyway 61 across which extends a key 62 mounted in the tool holder 18. The keyway 61 and key 62 are proportioned so that engagement between the key and the rearward end of the keyway limits forward movement of the sleeve 53 relative to the holder 18. The rearward extent of movement of the sleeve 53 relative to the tool holder is limited by engagement between the rearward end of the sleeve and the backup element 51.

A hold back lever 63 operates to engage a shoulder 72 on the sleeve 53 as the tools move toward the die assembly and hold the sleeve 53 spaced from the die assembly during the first phase of the upsetting operation. The hold back lever 63 is positioned on the die breast to permit shifting of the tool holder without interference and so it will not engage the second stroke tool assembly, but for purposes of illustration it has been shown in the plane of FIGURES 2 to 5. The lever 63 is clamped by a clamping bolt 64 to a torsion rod 66 anchored by a cross pin 67 in a mounting plate 68 secured to the die breast. The torsion rod 66 serves the dual functions of providing a pivot for the support of the hold back lever 63 and a high rate spring resiliently urging the hold back lever 63 in a counterclockwise direction. An adjustment screw 69 is threaded into the hold back lever 63 and is positioned to engage a stop surface 71 on the mounting plate 68. By threading the adjustment screw 69 relative to the hold back arm 63, it is possible to adjust the maximum degree of counterclockwise rotation of the hold back lever.

As the sleeve 53 is carried toward the die assembly 12 by the tool carrier 18, the spring 58 maintains the sleeve 53 in its forward extreme position illustrated in FIG- URE 3 until the shoulder 72 engages the hold back lever 63. The torsion rod 66 provides suflicient torque to overcome the action of the spring 58 when the shoulder 72 engages the hold back lever 63 to hold the sleeve spaced from the die assembly 12 as the tool holder 18 continues to move forward from the position of FIGURE 3 to the position of FIGURE 4. When the rearward end of the sleeve 53 engages the backup element 51, however, continued movement of the tool holder 18 relative to the sleeve 53 is prevented and the sleeve is carried by the tool holder forward to the position of FIGURE overcoming the torque of the torsion rod 66.

Reference should be made to FIGURES 3 through 6 for a clear understanding of the operation during the first working stroke. The first phase of upsetting occurs as the elements move between the position of FIGURE 3 and the position of FIGURE 4. During this phase of operation, a coning function occurs wherein the stock which will form the head of the blank is initially gathered and shortened. During the second phase of operation, which occurs as the elements move between the position of FIGURE 4 and the position of FIGURE 5, the upsetting continues with the sleeve 53 and tool 49 moving together. In the past it has been customary to perform these two operations in separate working strokes, however, it should be understood that in a machine incorporating this invention, the upsetting which occurs as the elements move from the position of FIGURE 3 through the position of FIGURE 4 to the posit-ion of FIGURE 5 is continuous in one working stroke of the machine.

As the tool holder moves forward on the first working stroke, the sleeve 53 is held in its forward position by the spring 58 until the shoulder 72 engages the holdback lever 63. During this portion of the movement, the blank 34 is moved into the

bores

44 and 54 until its ends engage a knockout 43 and the tool 4-9 as illustrated in FIGURE 3. Normally the holdback lever is adjusted by the screw 69 (illustrated in FIGURE 2) so that the shoulder 72 engages the hoidback lever 63 at substantially the same time the ends of the blank 34 engage both the knockout 4S and the tools 49. Therefore, the sleeve 53 remains stationary rela tive to the die assembly as the upsetting is initiated by the movement of the tools 49 beyond the position of FIG- URE 3.

During the first phase of upsetting which occurs as the tool moves from the position of FIGURE 3 to the position of FIGURE 4, the wall of the bore 54 laterally supports the blank and prevents buckling. In the illustrated embodiment, the diameter of the bore 54 is larger than the diameter of the blank 34 to provide clearance, but the clearance is proportioned so that the wall of the bore will engage and support the blank before buckling occurs. This clearance also insures that the increasing diameter of the stock produced by the upsetting will not cause tight frictional engagement between the bore 54 and the upsetting portion of the stock which engagement would produce a fin at the joint between the outer surface of the tool 49 and the surface of the bore 54.

In effect, the unsupported length of the blank 34 is equal to the spacing between the forward end of the bore 44 adjacent the flared portion at 46 and the forward end of the sleeve 53. This spacing is much shorter than the length of the portion of blank being upset and is proportioned to be short enough to prevent buckling.

As the tool 49 moves from the position of FIGURE 3 to the position of FIGURE 4, the first phase of upsetting occurs. During this phase, the right end of the blank is pushed along the bore 54 and the blank is upset to an intermediate condition illustrated in FIGURE 4 wherein the length of the upset portion is reduced and the diameter is increased.

The upsetting tool 49 and the sleeve 53 are proportioned so that the rearward end of the sleeve 53 engages the backup element 51 when the end of the tool 49 is flush with the end of the sleeve 53 as illustrated in FIGURE 4. It should be noted that at this point in the operation, the upset portion does not engage the wall of the bore 42 which forms the die cavity and that the upset portion is substantially symmetrical about a mid-plane through the upset portion. When the sleeve 53 engages the backup element 51, further relative movement between the tool holder 18 and the sleeve 53 is prevented and the sleeve 53 moves forward with the tool holder overcoming the force of 'the torsion rod 66. During the movement of the tools from the position of FIGURE 4 to the position of FIGURE 5, the upsetting continues and the intermediate blank 73 is completed. Buckling does not occur during this second phase of upsetting since the length of the portion of the blank being upset during this phase when compared to its diameter is below the critical ratio.

During the upsetting that occur as the tools move between the position of FIGURE 4 and FIGURE 5 the end surface 55 of the sleeve 53 cooperates with the end of the tool 49 to transmit the upsetting forces to the blank material. As illustrated in FIGURES 5 and 6 the area of engagement between the blank material and the surface of the sleeve 53 and tool 49 is substantially greater than the area of the end face of the tool 49. Therefore, the pressure distribution in the material being upset is substantially more uniform than if the sleeve 53 were allowed to move to its final position before upsetting commenced. This relatively uniform pressure distribution eliminates scrambled grain flow along the zone between the upset and the shank of the blank.

The end face 55 .of the sleeve 53 is formed slightly concave or conical having an angle preferably between 3 and 5'. By providing the concave end surface 55 on the sleeve 53 the intermediate blank illustrated in FIG- URES 5 and 6 is formed with an end surface which is slightly crowned rather than fiat, This compensates for the suck-in at the .start of the second blow when the extrusion punch first strikes the head of the blank and results in striking of only that portion of the top of the head around the extrusion punch instead of the entire head.

The upsetting progresses as the tools move from the position of FIGURE 4 to the position of FIGURE 5, and the upset portion engages the wall of the bore 42 along a zone midway between the ends of the portion being upset at that moment of engagement. The engagement at 65 between the mid-section of the upset portion and the wall of the bore 42 produce friction resisting forward movement of the material of the blank forward of the zone of engagement 65. Therefore, the head of the intermediate blank 73 is formed at the completion of the forward working stroke has the shape illustrated in FIGURE 6. It should be noted that the head of the intermediate blank 73 is not symmetrical about a lateral plane through its mid-section but rather the zone of en gagement 65 is closer to the upper end of the head. The clearance provided between the wall of the bore 42 and the rounded corner at 98 is larger than the clearance between the wall of the bore 42 and the rounded corner at 97 due to the frictional resistance to movement of the material caused by the engagement at 65 between the material being upset and the wall of the bore 42. This particular shape of the intermediate head produces a desirable result during the socketing operation since there is sufficient clearance adjacent the lower end of the head into which the head material can be displacement forged and the rounded corner at 97 tends to conform to the rounded corner required in the finished blank adjacent the upper end of the head.

By utilizing a method and apparatus illustrated and described in conection with the first working stroke, it is possible to upset a blank wherein the upset portion initially has a length exceeding its diameter by a ratio exceeding the critcal ratio which would normally result in buckling. Therefore, this invention permits greater degrees of upset in a single blow. Since the operation which would normally be completed in two separate upsetting blows is completed in one upsetting stroke, the flow of metal i continuous. Therefore, it is not necessary to re-establish metal flow and the loads on the tools are decreased and tool wear is minimized. The upsetting produced in accordance with this invention also results in high strength articles since the plastic flow of the material is substantially uniform and as a result, there is an absence of planes of weakness often produced by excessive localized flow.

When the header slide moves back from the die assembly after the completion of the first working stroke, the tool carrier 17 moves to position the second tool assembly 75 in alignment with the die assembly 12. The second tool assembly 75 includes a punch 76 having a hexagonal forward portion 77. A mounting plate 78 and backup plate 79 support the punch in the tool assembly 75. The two plates 78 and 79 are anchored in a sleeve 81 locked in the tool holder 18 by a lock pin 82. In order to prevent engagement of the holdback lever 63 by the sleeve 81, a recess is formed in the sleeve 81. Since the plane of the sections of the drawing does not pass through this recess, it does not appear therein.

A stripper sleeve 83 is slidable in the sleeve 81 between a rearward position in which the rearward end of the sleeve 83 engages the mounting plate 78 and a forward position determined by engagement between a flange 84 on the stripper sleeve and a shoulder 86 on the sleeve 81. A pair of stripper pins 87 and 88 extend through the two plates 78 and 79 between the stripper sleeve 83 and an operator 89. The operator 89 is slidably mounted in the backup plate 79 so that movement of the operator 89 forward relative to the backup plate 79 cause the stripper pins 87 and 88 to push the stripper sleeve 83 forward relative to the punch 76. A stripper lever 91 is pivoted at 92 on the tool holder 18 and is provided with a projection 93 which engages the rearward side of the operator 89 when the stripper lever is rotated in a counterclockwise direction.

After the completion of the second working stroke, as the header slide initiates its rearward movement, the stripper lever 91 is rotated in a counterclockwise direction causing the operator 89 to remain substantially fixed relative to the die assembly 12. This in turn causes the stripper sleeve 83 to remain against the die assembly 12 and retain the finished blank 94 in the die assembly 12 as the punch 76 is carried back by the header slide. The mechanism for operating the stripper lever 91 is not illustrated, but reference may be made to the United States Patent of Robert G. Friedman, No. 3,127,626, issued April 7, 1964, for a detailed description of a suitable mechanism.

Referring now to FIGURES 8 through 10, as the header slide moves forward on the second working stroke, the forward hexagonal cross-section portion 77 of the punch 76 enters the head of the intermediate blank 73 causing backward extrusion of the material of the intermediate head adjacent to the upper face thereof. The friction engagement at 65 between the intermediate head and the wall of the bore 42 resists forward upsetting of the material and assures that the backward extrusion will occur. As the end of the punch moves to a position within the zone of engagement at 65, the friction at this zone operates to resist further backward extrusion and the continued forward movement of the punch 76 causes lateral and forward displacement of the metal forward of the punch into the lower corner of the die. This lateral displacement of material adjacent the shank is possible because of the clearance initially provided between the wall of the bore 42 and the rounded corner 98 illustrated in FIGURE 6. Because the material filling this corner is laterally displaced by the punch, the grain flow lines of the finished article tend to conform to the shape of the head along the transition area between the shank and the lower end of the head. As a result, the finished blank has the proper grain structure for a maximum strength. The elimination of the backward extrusion toward the end of the second stroke also eliminates any tendency of the material at the corners to be dragged 1G backward along the punch by the extrusion flow which would occur if the blank formed by the first stroke filled the inner corners. Such dragging backward would cause unfilled corners in the finished head. Also, the fact that backward extrusion does not continue through the full stroke reduces the required tool pressure.

The outer corner at the periphery of the finished head is rounded and finished by the shaped recess 96 in the stripper sleeve 83. Since a somewhat similar curvature is present on the intermediate blank it is not necessary to produce substantial displacements with the stripper sleeve 83. Preferably, the convex form of the end face of the upset portion formed-in the first upsetting stroke is arranged so that it slightly over compensates for the suck-in of the material during the initial entry of the extrusion punch '76. Therefore, the stripper sleeve 83 initially engages the blank head in the zone immediately adjacent to the punch 76 providing a good finish of the end face of the blank with a minimum amount of pressure. The finished blank 94 is completed when the punch 76 reaches the full forward position of FIGURE 9.

As the header slide moves back from the forward dead center position, the stripper lever 91 is actuated to hold the stripper sleeve forward, thus stripping the punch 76 out of the finished blank 94.

After the header slide carries the tools clear of the die assembly 12, the knockout pin 48 is actuated in the usual manner to eject the finished blank from the dies, thus completing the cycle of operation.

By utilizing a method and apparatus incorporating this invention, it is possible to manufacture articles such as socket head cap screws in a double blow header. The tools of the first working stroke cooperate to produce substantial degrees of upset in a single working stroke without introducing re-entrant folds, planes of weakness caused by excessive plastic fiow of the metal in any par ticular zone or fins. This combined with the metal flow produced by the hexagonal punch 76 completes the article by filling the corners of the head and forming the socket.

In FIGURE 11 a second embodiment of this invention is illustrated which is used when it is necessary or desirable to form an intermediate blank with a conical recess in the head. In certain types of socket head cap screws, a chamfer is formed at the open end of the socket to facilitate the insertion of a wrench. When such a cap screw is manufactured, the upsetting tool 49 of the first working stroke tool assembly is formed with a conical end 102 and the tool projects forward of the sleeve 53 when the sleeve 53 is in its rearward position engaging the backup element 51. This forms a conical recess 103 in the face of the head of the intermediate blank 73 which remains in the finished blank a providing a chamfer 103a to guide the tool or wrench and facilitate its insertion into the socket formed in the second working stroke as illustrated in FIGURES l2 and 13. Because a substantial amount of clearance is provided between the bore 54 and the outer surface of the initial blank, as illustrated in FIGURE 3, any swelling of the blank end caused by the conical end 102, illustrated in FIGURE 11, does not produce substantial pressure between the end of the blank and the wall of the bore 54 so fins do not occur.

FIGURE 14 illustrates still another embodiment of this invention wherein the die structure is arranged for the production of blanks which are not threaded the entire length of the shank. In this figure similar reference numerals are used to designate similar parts but a prime is added to indicate that reference is made to the embodiment of FIGURE 14. In the previous embodiments the shank is provided with a uniform diameter. This diameter is equal to the pitch diameter of the threads rolled upon the blank and the stock is chosen to have a diameter substantially equal to this pitch diameter. In the embodiment of FIGURE 14, however, only a portion of the shank is threaded. T herefore, the stock 11 is chosen'having a diameter equal to the diameter of the unthreaded-portion of the shank.

The die positioned rearwardly of the die 41 is formed in two pieces, 43a and 43b. A bore 44a is formed in the die element 43a having a diameter equal to the diameter of the unthreaded portion of the finished shank. The die element 43b is formed with an extrusion land 44b, having a diameter equal to the pitch diameter of the threaded portion of the finished bolt. As the tool 49 is carried forward it engages the blank 34' and presses the forward end through the extrusion land 44b forming a portion of shank having a diameter equal to the pitch diameter of the threads to be rolled upon the blank. The portion of the shank'between the extrusion land 4411 and the head remains at the diameter of the unthreaded shank portion. Since the force necessary to perform the relatively small amount of extrusion is low when compared to the force required for upsetting, the blank moves into the position with its inner end against the knock-out pin 48' before any upsetting occurs.

In FIGURE 14 the elements are illustrated at the point in the stroke wherein the inner end of the blank 34' engages the extrusion die 43b and the opposite end engages the tool 49. The sleeve 53 is arranged so that the shoulder 72 engages the hold-back lever 63' at the beginning of the extrusion operation. Therefore, the sleeve is held stationary and serves to prevent lateral buckling of the blank during both the extrusion operation and the initial upsetting. During the upsetting operation occurring after the inner end of the blank engages the knock-out pin 48 all of the various elements function in the same manner as in the first embodiment with the sleeve 53' held stationary during the initial portion of the upsetting until the end face of the tool 49' is flush with the end face 55 of the sleeve 53 Thereafter the sleeve 53 and the tool 49' move as a unit to complete the upset. The socketing tools for the second working stroke are the same as illustrated in the first embodiment and this operation is not affected by the presence of the extruded portion of shank.

Referring to FIGURE 2, during the first working stroke, the second tool assembly is positioned to one side of the die assembly 12. A spring pressed finger 106 pivotally mounted on the die breast 11 at 167 extends into alignment with the stripper sleeve 83 during the first working stroke. A spring 103 resiliently biases the finger 106 away from the die breast. As the header slide moves forward during the first working stroke, the stripper sleeve 83 engages the end of the finger 10d and is moved to its rearward most position illustrated in FIGURE 2. This assures that the punch 76 will extend beyond the forward face of the stripper sleeve and be lubricated by oil sprayed on the tools and die. This also prevents the stripper sleeve from impacting against the die breast. A recess 109 is formed in the die breast 11 to receive the forward end of the punch 76 during the first working stroke. Referring to FIGURE 7, during the second working stroke, the sleeve 53 engages the die breast 11 to one side of the die assembly 12. Again a recess 111 is formed in the die breast to prevent damage to the forward end of the upsetting tool 49.

Although preferred embodiments of this invention are illustrated, it is to be understood that various modifications and rearrangements of parts may be resorted to without departing from the scope of the invention as defined in the following claims.

What is claimed is:

1. A machine for cold forging articles with socketed heads comprising a frame, a die in said frame having a die cavity, a slide reciprocable in said frame forward and away from said die through a cycle including two forward Working strokes, a first tool assembly on said slide operable to engage and upset said blank on the first working stroke, and a second tool assembly operable on the second working stroke to engage and socket the upset formed by the first tool assembly, said first tool assembly including a tool engaging the end of a blank in said die and upsetting such end until the upset portion thereof engages the cylindrical wall of said die cavity only at a zone intermediate its ends, said second tool assembly including a punch pressed into said upset portion during said second working stroke backward extruding a part thereof and displacement forging the inner part forward of said zone thereby filling said die cavity.

2. A machine for forming socket head articles comprising a die breast, a die in said breast adapted to receive one end of a cylindrical blank with the other end projecting therefrom, a slide reciprocable forward and away from said die, first and second tool assemblies on said slide sequentially engaging and working a projecting end on said blank on alternate forward strokes of said slide, said first tool assembly including an upsetting tool engaging the projecting end of said blank and upsetting said projecting end toward said die, support means surrounding and laterally supporting a part of said projecting end only during a first phase of the upsetting preventing buckling of said projecting end, said upsetting tool continuing to upset said blank during a second phase while the portion being upset is unsupported by said su port means, said second tool assembly including a punch pressed into said end of said blank during the second forward stroke of said slide forming a socket in the portion upset by said first tool assembly.

3. A machine for forming headed articles comprising a frame, a die in said frame, a slide reciprocable on said frame through a cycle having two forward working strokes, a first tool assembly on said slide positioned to engage and work a blank in said die on a first working stroke, a second tool assembly positioned to engage said blank in said die on a second working stroke, said first tool assembly including a sleeve slidably mounted on said slide for movement relative to said slide to a maximum forward position and in an opposite diretcion to a maximum rearward position, resilient means urging said sleeve toward said forward position, a tool extending into said sleeve formed with a conical end projection, said tool being fixed against movement relative to said slide in the direction of slide movement, and a hold back member engaging said sleeve overcorning the action of said spring means and preventing movement of said sleeve toward said die beyond a predetermined point until said sleeve reaches its rearward position relative to said slide and then permitting movement of said sleeve toward said die with said slide, said sleeve extending around the end of said blank providing lateral support therefore as said tool engages and initiates upsetting of said blank in said die and thereafter moving with said tool, said tool forming intermediate blank having a conical recess in the end thereof, said second tool assembly including a punch pressed into the head of the blank contained within said die during the second working stroke of said slide displacing material of the head into the corners of said die and forming a socket in said head extending from said conical recess.

4. A machine for forming headed articles comprising a frame, a die in said frame, a slide reciprocable on said frame through a cycle having two forward Working strokes, a first tool assembly on said slide positioned to engage and work a blank in said die on a first working stroke, a second tool assembly positioned to engage said blank in said die on a second working stroke, said first tool assembly including a sleeve slidably mounted on said slide for movement relative to said slide to a maximum forward position and in an opposite direction to a maximum rearward position, resilient means urging said sleeve toward said forward position, a tool extending into said sleeve fixed against movement relative to said slide in the direction of slide movement, and a hold back member engaging said sleeve overcoming the action of said spring means and preventing movement of said sleeve toward said die beyond a predetermined point only until said sleeve reaches its rearward position relative to said slide, said sleeve extending around the end of said blank providing lateral support therefore as said tool engages and initiates upsetting of said blank in said die and thereafter moving with said tool to continue the upsetting of said blank, said second tool assembly including a hexagonal punch pressed into the head of the blank contained within said die during the second working stroke of said slide pressing the material of the head into the corners of said die and forming a hexagonal socket in said head.

5. A machine for upsetting elongated blanks comprising a die adapted to receive one end of said blank, a

slide reciprocable toward and away from said die, a tool carried by said slide adapted to engage the other end of said blank and upset a portion thereof, a sleeve around said tool mounted for limited movement relative thereto between a forward and rearward position, said sleeve projecting forward of said tool when in its forward position and being proportioned to surround and laterally support said other end of said blank and prevent buckling thereof when said tool engages said other end, and hold back means operable to maintain said sleeve spaced from said die only when said tool engages and commences to upset said portion of said blank.

6. A machine for upsetting elongated blanks compris ing a die adapted to receive one end of said blank, a slide reciprocable toward and away from said die, a tool carried by said slide adapted to engage the other end of said blank and upset a portion thereof, a sleeve around said tool mounted for limited movement relative thereto between a forward and rearward position, said sleeve projecting forward of said tool when in its forward position and being proportioned to surround and laterally support said other end of said blank and prevent buckling thereof when said tool engages said other end, and hold back means operable to maintain said sleeve spaced from said die when said tool engages and commences to upset said portion of said blank, and drive means moving said sleeve with said tool when the portion of said blank being upset is sufficiently short to prevent buckling thereof thereby completing the upset of said portion.

7. A machine for upsetting elongated blanks comprising a die adapted to receive one end of said blank, a slide reciprocable toward and away from said die, a tool carried by said slide adapted to engage the other end of said blank and upset a portion thereof between said die and tool, a sleeve mounted on said slide around said tool for movement between a forward position and a rearward position relative to said too], said sleeve projecting beyond the end of said tool when in its forward position to provide lateral support for said other end of said blank, means maintaining said sleeve in said forward position as said slide moves toward said die until said sleeve reaches a predetermined position relative to said die in which said other end of said blank projects into and is laterally supported by said sleeve, said means then holding said sleeve substantially fixed relative to said die as said tool is carried toward said die initiating the upset of said blank, said means retaining said sleeve in said predetermined position until said sleeve is in said rearward position relative to said tool, and said means thereafter moving said tool and sleeve together toward said die completing the upset of said blank.

8. A machine for upsetting elongated blanks comprising a die adapted to receive one end of said blank, a slide reciprocable toward and away from said die, a tool carried by said slide adapted to engage the other end of said blank and upset a portion thereof between said die and tool, a sleeve mounted on said slide around said tool for movement between a forward position and a rearward position relative to said tool said sleeve projecting beyond the end of said tool when in its forward position to provide lateral support for said other end of said blank,

means maintaining said sleeve in said forward position as said slide moves toward said die until said sleeve reaches a predetermined position relative to said die in which said other end of said blank projects into andis laterally supported by said sleeve, said means then holding said sleeve substantially fixed relative to said die as said tool presses said other end out of said sleeve, and said means thereafter moving said tool and sleeve together toward said die completing the upset of said blank.

9 A machine for upsetting elongated blanks comprising a die adapted to receive one end of said blank, a slide reciprocable toward and away from said die, a tool carried by said slide adapted to engage the other end of said blank and upset a portion thereof between said die and tool, a sleeve mounted on said slide around said tool for movement between a forward position and a rearward position relative to said tool, said sleeve projecting beyond the end of said tool when in its forward position providing lateral support for said other end of said blank, first spring means maintaining said sleeve in its forward position as said slide moves toward said die until said one end projects into and is laterally supported by said sleeve, second spring means overcoming said first spring means when said sleeve reaches a predetermined position relative to said die and maintaining said sleeve in said predetermined position while said tool initiates upsetting of said blank until said sleeve reaches said rearward position relative to said tool, and drive means operably engaging said sleeve when said sleeve is in said rearward position relative to said tool carrying said sleeve with said tool to continue the upset of said blank.

10. A machine for cold forging articles with socketed heads comprising a frame, a die in said frame having a die cavity, a slide reciprocable in said frame forward and away from said die through a cycle including two forward working strokes, a first tool assembly on said slide operable to engage and upset said blank on the first Working stroke and a second tool assembly operable on the second working stroke to engage and socket the upset formed by the first tool assembly, said first tool assembly including a sleeve formed with an axial passage with a cross-section having a shape similar to the cross-section of the end of a blank positioned in said die and a cross-sectional area greater than the crosssectional area of said blank, said sleeve extending over the end of said blank to be upset during a first phase of the upsetting operation, an upsetting tool extending into and closely fitting said passage and engaging the end of said blank supported by said sleeve and upsetting such blank by pressing said end along said sleeve, said sleeve preventing buckling of said blank without binding confinement during said first phase, and means thereafter moving said sleeve and tool together during a subsequent portion of said first working stroke, said second tool assembly including a punch pressed into said upset portion during said second working stroke backward extruding a part thereof and displacement forging the inner part forward of the punch.

11. An ap aratus for upsetting a blank having a crosssection comprising a die, a tool assembly movable toward said die to upset a blank contained therein, said tool assembly including a sleeve formed with an axial passage having a cross-sectional shape similar to the cross-section of said blank and a cross-sectional area greater than the cross-sectional area of said blank, said sleeve extending over the end of a blank to be upset during a first phase of upsetting operation, an upsetting tool extending into and closely fitting said passage engaging the end of a blank supported by said sleeve and upsetting such blank by pressing said end along said sleeve, said sleeve preventing buckiing of said blank without binding confinement during said first phase, and means thereafter moving said sleeve and tool together during a subsequent portion of the upsetting operation.

12. An apparatus for upsetting a blank comprising a frame, a die on said frame, a tool assembly movable toward said die to upset a blank contained therein, said tool assembly including a tool operable to engage and upset the end of said blank and a sleeve around said tool movable relative thereto between a forward and a rearward position, spring means resiliently urging said sleeve toward said forward position in which it extends beyond the end of said tool, and a member mounted on said frame resiliently urged toward a first position and movable therefrom, said member engaging said sleeve as said sleeve is carried toward said die overcoming said spring and maintaining said sleeve in a predetermined position relative to said die during a portion of the movement of said tool toward said die and thereafter allowing said sleeve to move with said tool toward said die.

13. An apparatus for upsetting a blank comprising a frame, a die on said frame, a tool assembly movable toward said die to upset a blank contained therein, said tool assembly including a sleeve extending over the end of a blank to be upset during the first phase of the upsetting operation, an upsetting tool extending into said sleeve engaging the end of a blank supported by said References Cited by the Examiner UNITED STATES PATENTS 1,069,659 8/1913 Ferry 10 12 X 1,561,863 11/1925 Kuhne l()24 X 2,165,424 7/1939 Tomalis l07 3,182,342 5/1965 Kolec et al. l026 X FOREIGN PATENTS 921,907 12/ 1954 Germany.

74,221 3/ 1954 Netherlands.

ANDREW R. J UHASZ, Primary Examiner.