US2125272A - Manufacture of screws - Google Patents

Description

1933- H. c. ERDMAN' 2,125,272

MANUFACTURE OF SCREWS Filed June 24, 1937 5&6 fia I? fia. 18 field //''ci. 2].

2 M W fiai f/GJI 56.17 5619 I mvsmoa HARVEY 6f ERDMA/V BY 1M M w/ ATTORNEYS Patented Aug. 2, 1938 PATENT OFFICE- MANUFACTURE OF SCREWS Harvey 0. Erdman, Shaker Heights, Ohio, assignor to The National Screw & Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application June 24, 1937, Serial No. 150,092

3Claims.

This invention relates .to the manufacture of screws, and as its principal object, aims to provide improved apparatus for the production of screws of the type having a tool-receiving recess in the head thereof.

An object of my invention is to provide a novel form of punch or hammer for forming the toolreceiving recess in the heads of screws being produced whereby die breakage and the percentage of scrap or imperfect screws is reduced to a minimum.

Still another object of my invention is to provide improved screw forming apparatus embodying a hammer having a web-like projection for forming a screw-driver slot in the screw head being shaped and also having novel means for reinforcing the web-like projection.

Other objects and advantages of my invention will be apparent from the following description when taken in conjunction with the accompanying sheet of drawings in which Fig. 1 is a longitudinal sectional view showing a pair of dies acting on a screw blank;

Fig. 2 is an end view of the punch or. ham- 25 mer;

Fig. 8 is a longitudinal sectional view taken through the hammer;

Fig. 4 is a longitudinal sectional view taken through the hammer at approximately right angles to the sectional viewoi Fig. 3;

Fig. 5 is a side elevation oia screw blank produced by the dies and forming operation illustrated in Fig. 1;

Fig. 6 is a plan view of the blank; 1

Fig. '1 is a longitudinal'sectional view showing another pair or cooperating dies acting on a blank for another type of screw;

Fig. 8 is an end view of the hammer;

Fig. 9 is a longitudinal sectional view taken 40 through the hammer;

Fig. '10 is another longitudinal sectional view of the hammer takenat approximately right angles to the view of Fig. 9;

Fig. 11 is a side elevation oi a screw blank produced by the dies and forming operation illustrated in Fig. 'l; i

Fig. 12 is a plan view of the blank:

Fig. 13 is an elevational view, partly. in sec- 50 tion, illustrating cooperating dies and a iorming operation for another type of screw blank;

Fig. 14 is an end view of the hammer; v

Fig. 15 is 'a longitudinal sectional view taken through the hammer;

66 1'18. 16 is a longitudinal sectional view taken through the hammer at substantially right angles to the view of Fig. 15;

Fig. 17 is a side elevation of a screw blank produced by the dies and i'orming operation of Fig. 13;

Fig. 18 is a plan view of the blank;

Fig. 19 is a side elevation of a rough screw blank from which the completed screw blanks may be formed; 4

Fig. 20 is a partial side elevation of a tool which may be used for driving certain of the screws produced by my novel apparatus;

Fig. 21 is an end view of the tool, and

Fig. 22 is an end view of a similar tool of a cross-sectional shape to fit the tool-receiving recess of the screw blank of Figs. 11 and 12.

More detailed reference will now be made to the accompanying drawing in which I show the novel screw-forming apparatus of my invention adapted to the production of different types of screws. It should be understood however that the drawing is to be regarded as illustrative and that the invention may be embodied in various other similar devices and apparatus.

In Fig. 1 of the drawing I show a pair of cooperatingdie members 25 and 28 acting on a screw blank 21 to form the head 28 thereof to the desired shape, and to provide the head with a tool-receiving recess or slot 29. The die 26 serves as an anvil for supporting the blank 21 during the forming operation and has an axially extending opening 20 which shapes and sizes the stem ii of the blank during the fonning operation. The anvil 26 may also include a knockout pin 22 which forms the bottom of the opening ll and acts to elect the screw blank from the die after the forming operation has been completed.

The die member 2! is a hammer or punch which acts on the screw blank to form the head thereof to the desired shape and also to form. the tool-receiving recess 29 therein. For shaping or forming the screw head I provide the hammer with a recess 34 in the end thereof in coaxial relation to the stem forming opening 30 01' the anvil 2C. The recess 34 is of the desired depth and shape to properly form the rough blank 35 of Fig. 19 to the shape and form 01 the finished blank 21 of Figs. 5 and 6. During this forming operation the metal of the rough blank 25 is -squeersed and distributed to form a head of the binding type on the screw blank shown in Figs. 5 and 6.

Screws of this type are usually provided with a tool-receiving slot or recess in the head thereo! and heretofore this recess has been formed during the head-shaping operation by a projection on the hammer. Considerable difiiculty has been experienced with apparatus of this kind by reason of the hammer projection becoming broken during the repeated blows which it must strike during the production of screw blanks in rapid successlon. There has also been a high percentage of scrap or imperfect screw blanks resulting from the blanks sticking to the hammer and causing jamming.

In my improved screw-forming apparatus I provide the hammer 25 with an axial projection 36 for forming the tool-receiving recess in the head of the screw and this projection embodies novel characteristics which eliminate the difiiculties just mentioned. The hammer projection 36 comprises a web-like body or rib of metal 31 formed integral with the hammer and extending axially into the die recess 34 and transversely thereof. The web-projection 31 extends into the recess a distance corresponding with the desired depth which the tool-receiving recess is to have in the completed screw blank. To prevent breakage of this web-projection and to secure certain other important advantages, I provide a reinforcing boss or enlargement 38 which is located intermediate the lateral ends ofrthe web projection 31 and extends coaxially of the hammer for substantially the same distance or depth as the web-projection. By making the enlargement 38 of tapered form as indicated in the drawing, I find that it greatly strengthens the web-projection 31, and also assists in preventing the screw blanks from sticking to the hammer and producing jams which would result in delay in production, damaging or breaking the dies, and in alarge percentage of scrap screws. The upper end of the tapered enlargement 38 is formed to merge smoothly with the wall of the die recess 34 as by providing an annular fillet 39 of appropriate radius at the base of the projection.

I find'that the strength of the web projection 31 and its resistance to breakage can be further increased by connecting the outer or lateral ends 40 of this projection with the side wall of the recess 34 so that the metal of the web projection is integrally united with the metal of the hammer atthese points. I also find that in the manufacture of screws with die members of the form just described, the metal of the screw blank 4 is worked and thereby hardened which results in finished screws of greater strength and superior quality.

Inthe forming operation illustrated in Fig. 1 the enlargement 38 of the hammer projection is forced into the metal of the screw blank and displaces some of the -metal thereof laterally which assists in causing the outer or marginal portions of the screw head to be completely filled out and formed to the desired size and shape. During this operation the enlargement 38 forms an enlargement or pocket 42 in the tool-receiving recess of the screw blank being produced but this enlargement or pocket in the head of the completedscrew is. an advantage rather than a disadvantage because when-a screw driving tool 43, such as that illustrated in Figs. 20 and 21, engages in the screw recess the rib-like enlargement 44 of the tool will flt the corresponding enlargement or pocket 42 of the screw recess and will center the tool on the screw axis and also prevent lateral slipping or accidental disengage-' mentof the tool from the slot of the screw. The

wing portions of the screw slot to the correspond s ing portion of the driving tool.

In Fig. 7 of the drawing I have shown another pair of die members comprising cooperating anvil and hammer members 50 and 5| which act on a rough screw blank to produce a screw blank 53 having a round head 54 as illustrated in Figs. 11 and 12.

The anvil 50 is provided with a stem-forming recess 55 and with a knock-out pin 56 similar to the corresponding parts of the anvil of Fig. l. The hammer member 5| is provided with a die recess 51 of a rounded shape to form the round head 54 of the screw blank 53.

To form a tool-receiving recess or slot 56 in the head of the screw blank 53 I provide the hammer with a web-like projection 53 which extends axially into the recess 51 and transversely thereof as illustrated in Figs. 9 and 10. This web-like projection has its outer or lateral ends 60 united with the wall of the die recess and has an axially extending tapered enlargement 6| intermediate its ends. Instead of being of round cross-section as illustrated in Fig. 2, the enlargement 5| may be of non-circular cross-section, for example of diamond-shape, and forms a corresponding diamond-shaped enlargement or pocket 62 in the head of the screw'blank 53.

In Fig. 13 of the drawing I show cooperating anvil and hammer members 65 and 66 for forming the screw blank 61 which is of the type having a flat head 68. When a screw blank of this form is to be produced the hammer 66 need not be provided with a recess but does have an axially extending web-like projection 63 which forms the transversely extending tool-receiving slot or recess 10 in the head of the screw blank.

This slot may have its ends lying inwardly of the outer wall of the screw head, as is shown in this instance, or if desired may extend entirely across the head. In this embodiment of my invention the web-projection 69 of the hammer has a tapered axially extending enlargement H intermediateits ends and which is of substantially the same depth or length as the web-projection itself. During the forming of the screw blank 61 this enlargement forms the pocket or enlargement 12 in the head 63 of the screw blank. The outer or lateral ends of theweb-projection 63 may be inclined or tapered; as shown in Fig. 16, to form correspondingly inclined faces at the ends of the slot III.

For use with screw blanks in which the tool-receiving recess of the head has a diamond-shaped rovide a driving tool 14 having a corresponding diamond-shaped central ,rib portion I5. Al-- though I have illustrated and described two different forms of driving tools which may be used to advantage with the screw blanks formed by my novel apparatus, it should be understood however that the use of tools ofv the particular form here illustrated is not necessary and that a conventional form of screw driver may be used if desired.

From the foregoing description and the accompanying drawing it will now be readily understood that I have provided improvedscrewforming apparatus in which the hammer or punch of theme members is provided with a slot-forming projection capable of withstanding the repeated blows required to be struck during the production of screw blanks in rapid succession. It will be understood furthermore that by providing the hammer projection with a tapered enlargement, I secure not only a reinforcement and strengthening of the projection but also secure the advantage of preventing sticking of the screw blanks to the hammer and thus minimize jamming and the percentage of scrap screws.

-While I have illustrated and described my improved screw forming apparatus in .a somewhat detailed manner, it should be understood that I do not wish to be limited to the details of construction and arrangements of parts herein described, but regard my invention as including such changes and modifications as do not consti! tute a departure from the spirit of the invention web-like projection extending axially of the hammer and transversely of said working surface, said projection being adapted to be pressed into the blank to form a transverse slot therein and having substantially at its midpoint an axially extending enlargement for reinforcing the proiection against breakage.

2. In apparatus of the character described, a hammer having a die recess adapted to form a head on a screw blank and a projection extending axially of the hammer part-way into said recess and transversely thereof for forming a transverse slot in the screwihead being formed, said projection having its lateral edges joined to the wall of said recess and also having substantially at its midpoint an axially extending tapered enlargement for reinforcing the projection against breakage.

3. In apparatus of the character described, a screw-forming hammer having a tapered punch projection extending axially from a working face thereof and web-like portions connected with said projection and extending laterally in opposite directions therefrom, said tapered projection and web-like portions being of substantially the same depth but the punch being thicker in cross-section than said web-like portions.

HARVEY C. ERDMAN.

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