US3036367A - Method of making ball studs - Google Patents

Description

y 1962 B. E. RICKS 3,036,367

- METHOD OF MAKING BALL STUDS Filed June 23, 1958 Bernard 5. Held-a 3,036,367 METHUD F MAKING BALL STUDS Bernard E. Ricks, Birmingham, Mich assignor to Thompson Rama Wooldridge inc, a corporation of Ohio Filed June 23, 1958, Ser. No. 743,681 8 (ilaims. (Cl. 29-1495) The present invention relates broadly to the formation of a ball stud from a metal rod of constant crosssection initially, and is more particularly concerned with improvements in a method of making ball studs by punch and die extrusion techniques.

This application is a continuation-in-part of my pending application, Serial No. 704,460, which was filed December 23, 1957.

The application referred to discloses a method of forming ball studs which comprises providing a blank of predetermined diameter and length from coil stock or the like, locating the blank in alignment with a die having a cavity corresponding to the outer shape of the final stud with the exception of the entire head thereof, and directing against one end of the blank a first punch to provide upon said blank the stem, taper, shank and portion of the head ultimately desired. At least one additional punch is then directed at the center of the partially shaped head to form a thimble-shaped cavity therein, and this is followed by use of a die having a concave cavity which forms the stud head into the desired ball-shaped configuration. The thimble-shaped recess is thereby converted into an essentimly round inner cavity in the head providing a lubricant reservoir for the tie rod socket or other structure within which the ball stud is normally received.

In the practice of the method described in my copending application, it has been found desirable, preparatory to formation of the generally thimble-shaped recess, to first provide in the partially formed head a shallow cavity of a generally concave configuration. There is accordingly normally required two pairs of punches and dies prior to the final head forming step. I have now discovered, however, that one of the intermediate forming steps may be eliminated, and further, that substantially improved results are obtained in the forming operation by providing in the preliminary head shape a shallow lubricant recess whereby any possibility of punch sticking during subsequent forming steps is rendered essentially remote.

It is therefore an important aim of the present invention to provide improvements in the ball stud forming methods disclosed in application Serial No. 704,460.

Another object of this invention lies in the provision of a method of making ball studs wherein during one of the forming steps a lubricant recess is shaped into the preliminarily formed head of the stud to greatly facilitate the subsequent head forming step.

A further object of the present invention is to provide a ball stud forming method which utilize punch and die members of relatively simple construction assuring pro duction of an article substantially superior to that obtained from the earlier steps of blanking, machining and grinding.

A still further object of this invention is to provide a ball stud forming method which comprises forming a segmental spherical head portion at one end of a metal rod of constant cross-section initially and during said forming step providing a relatively shallow lubricant re cess in the head portion, directing a punch member into said segmental spherical head portion and displacing a central portion of said head portion laterally and axially to form a substantially cylindrical cavity in the head portion and generally cylindrical extended wall por- 3,036,367 Patented May 29, 1962 ice tion of generally uniform thickness surrounding said cavity, and die forming the extended wall portion to a generally spherical contour complementing the segmental spherical contour of said head portion.

Other objects and advantages of the present invention will become more apparent as the description proceeds particularly when taken in connection with the accompanying drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the same:

FIGURE 1 is a view of a typical blank from which the finished ball stud may beformed;

FIGURE 2 is a sectional view of a first forming die showing the stud blank being directed therein by the first punch and die member;

FiGURE 3 is a sectional View of the die of FIGURE 2 and showing the partially formed ba-ll stud having a lubricant recess in the head portion thereof;

FIGURE 4 is a sectional view of a third die showing shape from FIGURE 3 prior to further formation of the stud head portion;

FIGURE 5 is a sectional view of a third die construction illustrating the shape of FIGURE 4 prior to final forming of the head portion; and

FIGURE 6 is a view, partially in section, of the finished ball stud as formed in the die construction of FIGURE 5 Referring now to the drawings, and first to FIGURE 6 thereof, a full ball stud 10 as produced in accordance with this invention comprises a stem 11 of generally uniform diameter, which ultimately may be threaded by cutting or rolling, and one or more tapered portions 12 and 13 having diameters greater than that of the stem 11. Integral with the tapered portions is a shank 14 of generally uniform cross-section throughout its length and upon which an integral head 15 is received. The head is generally circular in cross-section, as shown, and is provided interiorly thereof with a generally dome or bellshaped cavity 16 connecting with an open-ended passage 17 located in generally the center of the top of the head portion. As was stated in my earlier filed application, the passage 17 provides a flow path for lubricant into and out of the cavity 16, and said cavity thereby constitutes an effective grease reservoir that can be drawn upon throughout the life of the tie rod socket or other structure with which the bail stud v10 is associated. As also was stated, when ball studs are manufactured by customary lathe cutting operations, the head of the ball stud is completely closed, and provision of the cavity 16 provides a means by which the life of the tie rod socket or other structure may be substantially increased.

A feature of the present invention, and constituting one of the improvements upon the ball stud forming method disclosed in application Serial No. 704,460, is the elimination of one of the cold heading steps in the production of the article of FIGURE 6. Referring now to FIGURE 1, an initial step in the present process is the provision of a length of blank material which may be cut continuously from coil stock to the desired diameter and length. As is known in the art, a structure comprising a quill and cutter insert is effective for this purpose. Designated as 18, the blank is then located partially within and in alignment with the axis of a cavity 19' of a die member 20. The cavity 19 corresponds in general to the outer shape essentially of the ball stud 10, with the exception of the ultimate portion 15 thereof, however, it will be noted that the stem, taper and shank portions of the final shape are of lesser diameter and greater length than the forming surfaces of the cavity 19. Specifically, the cavity includes, a beveled shoulder 21 against which is formed the beveled end 22 on the stud 10, and a sectherewithin.

'in FIGURE 3.

providing the outer diameter of the shank portion 14 is a cavity section 26 of generally constant diameter, and at the outer :Or upper end of the cavity 19 is a section 27 of substantially semi-circular or semi-spherical shape within which a configuration is shaped providing after further forming the lower half portion of the fully rounded head 15, shown in FIGURE -6.

Cooperating with the die member 29, first to maintain the blank 18 in axial alignment with the cavity 19 thereof,

and thereafter to form generally rounded shoulder portions on the head partially completed in the structure of FIGURE 2, is a sleeve member 28 having an axial'bore' 29 therein corresponding in diameter to the outer diameters of the blank 18 and punch member 30 movable The necessary tolerances are of course provided to assure a smooth working of the parts. The

"sleeve member 28 travels axially independently of the punch member 30 and a retainer member, 31 associated process the blank 18 is located with respect to the die cavity 19 in the manner shown and circumferentially surrounded by the sleeve member 28 and received within the bore 29 thereof. The die cavity section 27 of the cavity 19 and recess or cavity 32 of the sleeve member 28 form an essentially continuous surface surrounding the blank 18, and the die and sleeve member 28 abut one another in the manner shown. 30 -and retainer member 31 are then caused to move axially toward the die 20 to extrude the blank 18 into contact with the die surfaces 21,23, and 24 to 27 formed in thedie cavity 19. Essentially simultaneously,

metal movement radially and axially into the recess or cavity 32 of the sleeve member .28 occurs to form a partially completed shape 33 of the configuration shown As clearly appears therein, the shape 33 is provided with a generally rounded shoulder portion 34 produced by axial travel of the punch member 30 cooperating with the die cavity section 27 of the die 20 and cavity 32 of the sleeve member 28. The rounded shoulder portion 34 complements the main body portion of the partially formed head on the shape 33, and radially 'inwardly of the shoulder portion 34 is a shallow recess or cavity 35 (FIGURES 3 and 4) produced during continued axial travel of the punch member 30 a limited amount following the initial formation of the other portions of the shape 33. At the opposite end of the die "cavity 19 the shape 33 bottoms against a knockout pin .or trap 35 is provided with a generally fiat bottom 38 and j substantially vertical side walls 39 connecting therewith to present a relatively shallow cylindrical recess. Provision of a lubricant trap or recess in the partially com- ;pleted shape 33 has been found by actual practice to greatly facilitate performance of the subsequent forming The punch member 4 steps by eliminating any possibility of punch sticking in the further steps and additionally, is productive of an improved quality product. A number of different lubricants are productive of the results desired, and those which have been used with consi erable success are Dasco and Vantrol No. 5510-Z, the latter material being more preferred at present. The Dasco material is supplied to the trade by D. A. Stuart Oil Co., and the Vantrol lubricant by Van Straaten Chemical Co, both companies having their oflices in Detroit, Michigan. It will be appreciated, howeventhat other lubricants are suitable, and since the forming steps are performed with unheated, or even externally cooled, punche and dies, the number of lubricants effective to prevent punch sticking are substantial.

The preferred lubricant remains quite viscous and does not drain out of the-cavity before it is trapped by the punch'which it is to lubricate. The cavity 35 may be filled with this lubricant just prior to receiving the punch by feeding a pressurized jet of the lubricant into the cavity, by painting the end of the stud head with a brush to fill the cavity with lubricant or by ejecting lubricant through a longitudinal hole on the punch. Of course the die and punch can be oriented into an inclined or vertical position to present the cavity 35 in an upright nonraining position.

A predetermined quantity of lubricant 35a is located in the cavity 35 of the initially formed shape 33, and

said shape then transferred to a die of the construction shown in FIGURE 4. The die disclosed is designated generally by the numeral 49 and is provided with a cavity 41 having shaping surfaces conforming essentially to the stem, taper and shank portions 1114 of the tin- .ished article 10 of FIGURE 6. Accordingly, and proceeding axially toward the wider portion of the cavity 41, there is included a beveled surface 4-2 connecting with a generally cylindrical surface 43 upwardly of which is a beveled extruding surface 44. A tapered shaping surface 45 connects therewith and upwardly of said surface 45 is a generallycylindrical cavity or extruding surface 46. The final segment of the cavity 41 is generally dome-shaped as indicated at 47, and accordingly includes a substantially semi-spherical portion 48 and a generally cylindrical portion 49. At the opposite end of the cavity 41, a knockout pin or plug 50 is provided to facilitate removal of the shape formed in said cavity 41.

Cooperating with the die member 40 and cavity 41 therein is a punch member 51 carried in a retainer 52 and shaped to include a tapered or pointed nose portion 53 formed at the end of a generally cylindrical shank portion 54, said punch member 51 bottoming in the retainer 52 by means of beveled portion 55 axially outwardly ofwhich is a generally cylindrical end portion 56. While variations may of course be practiced, a ten (10) degree angle on the pointed end portion 53 of the punch 51 has produced particularly successful results to-date. Further, while the punch 51 may be formed from various materials, a particularly suitable steel composition is that identified as Neatro by its producer, Vanadium Alloys Steel Company of Latrobe, Pa. The punch was hardened to 6061 Rockwell C, and the end 53' finished to approximately four micro inches.

'33 is elongated by extrusion along its stem, taper and shank portions. Thus, it is to be noted from a comparison of the stem, taper and shank extruding surfaces of the dies 20 and 40 that the surfaces 4346 of the die 40 are of a relatively greater axial length than the surfaces 23--26 of the die 20. Accordingly, during the extrusion step performed in the die 40, the stem, taper and shank portions of the shape 33 are elongated or lengthened to essentially the length and outer diameter of the final article of FIGURE 6.

Essentially simultaneously with a lengthening and diameter reduction of the stem, taper and shank portions of the shape 33, the punch 51 moves the metal mass of the head portion of the shape 33 generally axially toward the wider diameter opening of the cavity 41 and into contact with the cavity forming surface 47. By extruding contact with the semi-spherical portion 48 and generally cylindrical portion 49 of the cavity 41 the head formation upon completion of the step shown in FIG- URE 4 is generally bell-shaped, or in cross-section, substantially U-shaped. There is thus formed by the sec ond extruding step a shape 57 (FIGURE 5) having a head portion 58 characterized by a Wall or skirt portion 59 of generally uniform thickness. A cavity or recess 60 is formed in the head portion 58 which is essentially cylindrical, corresponding to the outer diameter of the shank portion 54 of the punch 51, and said cavity 60 includes a tapered bottom 61 formed by pointed end 53 of the punch 51.

During metal mass movement in the manner described, lubricant contained in the trap or recess 35 of the shape 33 flows or moves in covering contact with the working surfaces of the punch 51, as well as coating the metal surfaces of the shape head portion during axial movement thereof by action of the punch 51 and die 40. A film or layer is accordingly present between the punch outer diameter and inner diameter of the head shape being formed so that no noticeable sticking of the punch in the head occurs, and upon completion of the second extruding step, the punch 51 may be readily withdrawn from the head portion 58 of the shape 57. Accordingly, by provision of the lubricant trap or recess 35, the extruding operation is considerably facilitated and the possibility of damage to the part being formed by reason of punch sticking is eliminated.

The shape 57 may then be removed from the die 40, which may require use of the knockout pin 50, and is then transferred to a die construction of the character shown in FIGURE 5. There is provided a die 62 having a cavity 63 therein including surfaces 64, 65, 66, 67 and 68 corresponding to the surfaces 42-46 of the die member 40 of FIGURE 4. Accordingly, during the extrusion or shaping step of FIGURE 5, there is essentially no metal movement in the regions of the shape 57 comprising the stem, taper and shank portions. At the outer or upper end of the cavity 63, however, there is provided a concave or semi-spherical cavity portion 69 conforming in contour to generally the lower half portion of the head of the final ball stud 10 of FIGURE 6. At the opposite end of the cavity 63 there may be included a knockout pin 70 to facilitate removal of the shape formed in the die 62 and against which the shape 57 normally bears receiving a portion of the force exerted during the shaping step of FIGURE 5.

Cooperating with die member 62 in the final forming step is a die member or curling tool 71. The latter member 71 has a cavity 72 of semi-spherical shape complementing the cavity portion 69 within the die member 62. Accordingly, when a full stroke or complete travel of the die member 71 has been made, and the dies 62 and 71 abut one another, a generally fully rounded cavity is provided by the mating cavities 69 and 72, respectively. Generally centrally of the die member 71 and axially aligned with the cavity 63 in the die member 62 is an opening 73 preferably extending completely therethrough.

After location of the shape 57 in the die cavity 63 in the manner shown in FIGURE 5, the stem, taper and shank portions of the shape 57 being in contact with the surfaces 6568 of the cavity 63, and the partially formed head 58 of said shape seated upon the semi-spherical cavity portion 69, the die member 71 is moved axially toward the die 62 to fold or form the Wall portion 59 of the shape 57 radially inwardly and downwardly. During relative movement of the dies 62 and 71 toward one another, the wall or skirt portion 59 of the shape 57 is first contacted by the relatively wider portion of the die cavity 72, and during continued travel of the die member 71 said wall or skirt portion 59 slides or moves upon the cavity surfaces until the dies 62 and 71 contact or abut one another. The final ball stud shape as shown in FIGURE 6 is thereupon completely formed, and the final article 10 may thereupon be removed from the die 62 utilizing if required the knockout punch or pin 70. As shown, the die 71 of FIGURE 5 is supported in a retainer 74.

It may be seen from the foregoing that applicant has provided a novel ball stud and method of making the same which effects even greater production economies than the method disclosed in application Serial No. 704,- 4-60. A cold heading step has been eliminated and any possibility of punch sticking during the forming operation rendered essentially remote. Steels of various compositions may be formed with ease and accuracy utilizing this method, and specifically, applicant has produced ball studs from such steels as SAE 8614, 8615 and 8650. Accordingly, at least as high as 50 carbon steels may be formed with success following the concepts herein disclosed. No heating of the dies or metal being Worked is required, and those versed in the art were previously of the firm opinion that metal could not be moved in the manner disclosed by applicant without resort to the use of heat. Further, the die structures required are of relatively simple construction, and the steps may be practiced with existing retainers and related structure.

It is to be understood that variations and modifications may be practiced in the articles and processes herein disclosed without departing from the spirit of the invention or the scope of the subjoined claims.

I claim as my invention:

1. In a method of forming a ball stud from a metal rod, the steps of contacting said rod with a first punch having a relatively flat active end face and upsetting an enlarged head portion at one end thereof, simultaneously forming a lubricant receiving recess in the end of the head with the active end of said first punch, placing lubricant in said recess, inserting a second punch into the recess, trapping lubricant between the second punch and head, displacing a central portion of said head portion axially around said second punch to form an extended skirt portion, and die forming said extended skint portion to a contour complementing the contour of said head portion.

2. In a method of forming a ball stud from a metal rod, the steps of contacting said rod with a punch having a relatively flat active end face and forming a head portion at one end thereof, simultaneously forming a lubricant receiving recess in said head portion with the active end of said punch, placing lubricant in said recess, displacing a central portion of said head portion axially while confining the lubricant and the surface of said head portion to form an extended skint portion, and die forming said extended skint portion to a desired con-tour.

3. In a method of forming a ball stud from a metal rod of constant cross-section initially, the successive steps of contacting said rod with a punch having a relatively flat active end face and forming a segmental spheiical head portion at one end thereof while essentially simultaneously forming a relatively shallow lubricant receiving recess therein, with the active end of said punch displacing a central portion of said head portion axially to form an extended wall portion defining therein a cavity of uniform diameter, essentially simultaneously reducing the diameter of the remaining portion of the rod, and die forming said extended wall portion to a generally spherical contour complementing the segmental spherical contour of said head portion.

spartan? 4. Ina method of forming a ball stud from a metal rod of constant cross-section initially, the steps of moving an unheated metal body' of uniform diameter axially into a stepped die-cavity by contacting said body with a first punch having a relatively fiat active end face and forming at one end a segmental spherical head portion while confining the movement of metal flow in one axial direction to form a generally smoothly curved end surface on said head portion, essentially simultaneously indenting said head portion to form therein a relatively shallow lubricant receiving cavity with the active end of said first punch, forming in the head portion generally centrally thereof a substantially cylindrical cavity and a skirt pontion surrounding the same, and moving the skirt portion radially inwardly to form a generally spherical contour complementing the segmental spherical contour of the head portion.

5. In a method of forming a ball stud from a metal rod of constant cross-section initially, the steps of moving 'a iust punch member with a relatively fiat active end face axially against one end of a metal rod of constant crosssection and directing the same into a die cavity while confiningthe path of meta flow in an opposite axial direction to form a segmental spherical head portion at one end thereof, continuing the punch movement while confining the head portion to form a relatively shallow recess therein with the active end of said first punch member, directing a second punch member into the recess and displacing the central portion of the head portion axially,

to form a uniformthickness wall portion, and directing a die member into surrounding contact with the extended wall portion and moving said die member axially to form -a generally spherical contour complementing the segmental spherical portion of said head portion.

6. In a method of forming a ball stud from a metal rod va. second punch member. into the recess and displacing the central portion of the head portion axially to form a uniform thickness wall portion and reduce the diameter of the body portion, and directing a die-member into surrounding contact With the extended wall portion and moving said die member axially to form a generally spherical contour complementing the segmental spherical portion of said head portion While maintaining the body portion to essentially its previously formed diameter. 7

7. In a' method of forming a ball stud from a metal rod 8 of constant cross-section initially, the steps of moving a first punch member with a'relatively flat active end face axially against one end of a metal rod of constant crosssection and directing the same into a die cavity while confining the path of metal flow in an opposite axial direction to form a segmental spherical head portion at one end thereof, continuing the punch movement while confining the head portion to form a relatively shallow recess therein with the active end of said first punch member, directing a generally cylindrical second punch member having a'pointed end into the recess and displacing the central portion of the head portion axially to form a uniform thickness wall portion and a cavity having a bottom conforming to the pointed end of the punch member, and

directing a die member-into surrounding contact with the 7 extended Wall portion and moving said die member axially to form a generally spherical contour complementing the segmental spherical portion of said head portion.

8. In a method of forming a ball stud from a metal rod of constant cross-section initially, the steps of moving an unheated met-al'body of uniform diameter axially into a stepped die cavity by contacting said body with a first punch having a relatively fiat active end face and forming at one end a segmental spherical head portion While confiningthe movement of metal flow in one axial direction to form a generally smoothly curved end surface on said head portion, essentially simultaneously indenting said head portion to form therein a relatively shallow lubricant receiving cavity with the active end of said first punch locating a lubricant in said cavity, forming in the head portion generally centrally thereof a substantially cylindrical cavity and a skirt portion surrounding the same, and moving the skirt portion radially inwardly to form a generally spherical con-tour complementing the segmental spherical contour of the head portion.

References (Zited in the file of this patent UNITED STATES PATENTS 529,597 Cayley Nov. 20, 1894 761,778 Mercader June 7, 1904 1,266,485 Kingston May 14, 1918 1,913,459 Skillman et al June 13, 1933 1,978,371 Pur-tell Oct. 23, 1934 2,265,839 Hufferd Dec. 9, 1941 2,462,138 Spangenberg Feb. 22, 1949 2,556,033 Flumerfelt June '5, 1951 2,618,049 Flumerfelt Dec. 18, 1952 2,727,768 Latzen Dec. 20, 1955 2,748,464 Kaul June 5, 1956 2,755,543 Dunn et al July 24, 1956 2,821,016 Dickson Ian. 28, 1958 V FOREIGN PATENTS 603,582 Great Britain June 13, 1948

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