US2024593A

US2024593A - Method of making square-head screws

Info

Publication number: US2024593A
Application number: US724367A
Authority: US
Inventors: Moore Harrington
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-05-07
Filing date: 1934-05-07
Publication date: 1935-12-17
Anticipated expiration: 1952-12-17

Description

Dec. 17, 1935. H. MOORE 2,024,593

METHOD OF MAKING SQUARE HEAD SCREWS Patented-Dec. 17, 1935 UNITED STATES PATENT OFFICE METHOD OF MAKI G SQUARE-HEAD SCREWS This invention relates to an improved method of making screws having square heads or heads of other polygonal shapes, the method being more especially adapted to be practiced with automatic machinery for carrying out the several steps in the making of screws.

It is an object of the invention to make squarehead screws without heating the stock, and to make them in such a manner that they will be substantially free from internal weakness and from excessive variation in the shape and dimensions of the head.

For a more complete understanding of themvention, reference may be had to the description thereof which follows, and to the drawing of which Figure 1 is a perspective view of a typical square-head screw made according to the invention. a

Figure 2 is a fragmentary elevation of wire stock from which the finished screws are made.

Figure 3 is an elevation, partly broken away to show in section, of a screw'at an intermediate stage of its production.

Figure 4 is a fragmentary sectional view of mechanism for swaging the head of a screw.

Figure 5 is a section on the line 5-5 of Figure 4;

Figure 6 is a fragmentary section similar to Figure 4, showing the parts in a different position of operation.

Figure '7 is a section on the line 1-1 of Fig- .ure 6.

erably employed, a piece of such stock being illustrated at H] in Figure 2. The stock may be cut as at H to provide a blanklZ of predetermined length just suflicient for the finished screw. An end portion of the blank I2 is then swaged by suitable mechanism well known in the art to form a mushroom head l3 having a top face M which is flat or nearly so, and a rounded shoulder [5. This mushroom head is formed preferably prior to the formation of any screw thread on the shank of the blank. The head I3 is of substantially greater diameter than the shank, so that the headed blanks can readily be fed into an automatic thread-cutting machine. In swaging the end portion of the blank l2 to form the head E3, the volume of the head is carefully predetermined so as to be just sufficient to form thehead-of the finished screw.

After the formation of the mushroom head [3 on'the blank 12, a screw'thread lBis cut or otherwise formed on the shank of the blank l2. The blank is then ready for the final step of pressing the mushroom head laterally at spaced points so as to swage the head into a'shape having an approximately polygonal cross section, preferably square. This operation is preferably performed while the blank is cold. To this end, the blank may be inserted in a suitable hole I! in a holder l8. Associated with the holder l8 are pressing members 2!], the hole I! being of such a depth that the mushroom head 13 is in correct position for engagement by the pressing elements 20. In the apparatus illustrated on thedrawing, four pressing elements 20 are illustrated for the formation of a square-headed screw, but it is evident that any desired number from two up can be employed to form heads having a plurality of flat side faces. In order to hold the blank in place in the hole I! during the pressing operation, a spring-pressed plunger (not shown) preferably bears on the top face it of the mushroom head, this plunger being adapted to yield readily, so that, when the head is swaged, the axial flow of the. metal is not impeded by the yielding plunger. When the blank is properly in position as illustrated in Figures 4 and 5, the pressing elements 20 are forced to the position illustrated in Figures 6 and 7, these pressing elements engaging the mushroom head l3 laterally at spaced points. The pressing elements 2% form fiat faces on the sides of the head and swage the head into the approximate square shape illustrated at 22 in Figures 6 and '7.

The size and shape of the mushroom head are preferably such that, when the sides are pressed a the mushroom head It. Hence, since the volume of the head is unchanged by the swaging operation, the axial length of the squared head must be greater than that of the mushroom head. This increased axial length of the head results from an axial flow of the metal as the mushroom head is laterally pressed. This operation is such as to create no internal faults in the screw, the head of the screw thus formed being fully as strong as those of screws made by previously known and practiced methods.

I claim:

1. A method of making a screw, which comprises swaging an end portion of a piece of wire stock of predetermined length to form a mushroom head having a predetermined volume just suflicient for the head of the finished screw, forming a screw thread on the shank of said piece, and thereafter cold-pressing the sides of said mushroom head simultaneously at a plurality of spaced points to swage the head into a polygonal shape having an increased axial length and a minimum cross-sectional dimension substantially equal to the'dimension of the shank.

2. A method of making square-headed screws,

which comprises swaging an end portion of a piece of wire stock of suitable length to form a mushroom head of predetermined volume just suflicient for the head of the squared head to be formed, screw-threading the shank of said piece of stock, thereafter supporting the threaded piece so as to be capable of yielding axially, and cold-pressing the head of the piece laterally at four spaced points to form a squared head having a diagonal substantially equal to the diameter of the mushroom head before the pressing operation and a minimum diametrical dimension substantially equal to the diameter of the shank.

HARRINGTON MOORE. l5