US3283638A - Socket head screw - Google Patents

Description

1966 c. H. ANSINGH SOCKET HEAD SCREW Filed May 4., 1964 FIG. 4

INVENTOR. CARL H ANS/NGH Attornev United States Patent Canada Filed May 4, 1964, Ser. No. 364,392 1 Claim. (Cl. 859) This invention relates to improvements in screws and the principal object of the invention is to provide a screw which can be driven under high torque without danger of tool slip off or twisting off of the head and which can be readily removed by means of a :pair of pliers or wrench where the workman does not have an appropriate screw driver.

Another important object is to provide a screw as aforesaid which will be economical to produce and will be of neat attractive appearance.

While slot head screws are vary widely used where appearance or the development of high driving torques are not a factor, due to the tendency of the driving blade to slip off the slotted screw head and mar the surrounding surface, such screw are not usually employed with for example, the enamelled or painted surfaces of appliances or the like. In such cases socket type screws are employed and of the presently marketed screws the square recess socket screws as described in my Canadian Patent Number 588,063 are best adapted to preclude tool slip off, especially where a high torque is required to drive in the screw.

Because socket type screws require special driver tools of different size for different size screws, a workman or other person may not have the proper tool available to remove the screws when desired.

According to the present invention, this problem is overcome by forming the head of a square recessed socket screw as a hexagonal configuration whereby the screw may be driven by the appropriate square bit without danger of tool slip off and later may be removed by means of a wrench or a pair of pliers,

It will be understood that the forming of a socket in a screw head will reduce the amount of metal in the head for a given head circumference in the usual circular screw. For the socket to usefully coact with a driving bit, it must be out of round and so the provision of the socket also creates a problem of variations in socket wall thickness depending on its shape relative to the head circumference. This problem is not too difficult to solve where the screw head is circular since the circumference may be adjusted to provide at the point of minimum socket wall thickness sufficient metal to withstand the requisite driving torque load.

Where the head is made out of circular shape, for example, hexagonal shape, the problem becomes much more complicated since the new non-circular shape tends to create stress variations in the head not present in the circular head and the location of the socket in relation to the non-circular head becomes important in order to preclude head splitting under app-lied torque without requiring the head to have an undesirable size. It is, therefore, an important feature of the present invention to provide a relationship between an out of circular head and a socket formation through which the appropriate driving torque can be developed without requiring an excessive head size. In this connection, according to the invention, this problem is overcome by utilizing a square socket in a hexagonally headed screw and orienting two of the sides of the square of the socket to be substantially parallel to a pair of opposing sides of the hexagon whereby the diagonals joining the corners of the socket square are in angular relation to the lines joining the mid points 3,283,638 Patented Nov. 8, 1966 of the opposing sides of the head, the distance between such mid points being the minimum head dimension. Thus, the arrangement provides for a location of the corners of the square at which critical stresses are developed in driving wheneb-y these corners are displaced from the minimum head dimension.

These and other objects and features will become apparent from the following details description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a top plan view of a screw embodying my invention;

FIGURE 2 is a mid vertical section partly broken away, taken along the line 22 of FIGURE 1;

FIGURE 3 is a mid vertical sectional view partly broken away taken on line 3--3 of FIGURE 1;

FIGURE 4 is a side elevational view partly broken away of the screw of FIGURES l to 3.

With reference particularly to FIGURE 1, the screw generally designated at 1 is provided with a hexagonally shaped ,head 2, providing 6 flat sides 3 at the outer circumference thereof. I

As shown in FIGUR'ES 2 and 3 taken in conjunction with FIGURE 1, the head 2 is bevelled as at 4 outwardly and downwardly from a top circular configuration 5 to the sides 6, the bevelled distance, of course, being greater at the corners formed by the adjoining sides 3 than at the mid points of these sides as shown in FIG- URES 2 and 3, respectively. As shown in FIGURE 3, the sides 3 of the hexagon are substantially tangential to the circular configuration 5.

The underside of the head is also prerably similarly bevelled at 6, the bevel extending outwardly and upwardly from a bottom circular configuration 7. Thus the sides 3 are generally arcuately bounded at the top and bottom and are of increasing axial depth from a minimum at the corners or apices 17 to their mid points.

The head 2 is provided with a central socket 8 of square cross section with the side walls of the socket preferably tapering slightly inwardly and the socket terminating in a conical bottom 9 as described in my Canadian Patent Number 588,063. The entrance to the socket 8 is also preferably bevelled as at 10.

The square cross-sectional socket 8 is preferably oriented in relationship to the hexagonal head 2, so that two of the sides 11 of the square socket are substantially parallel to a pair of opposing sides 3 of the hexagon circumference of the head. The other pair of sides 11 of the square socket will thus be bisected by a line joining one opposing pairs of apices formed by adjoining sides of the hexagon of the head, that is, by the line 22 in FIGURE 1. This arrangement locates the corners 12 of the square socket so that a line 13 drawn as a diagonal through the corners 12 will be inclined to a line 14 joining the mid points of a pair of opposing sides 3 of the square socket, the line 14 constituting the right bisec-tor of such sides 3. Because of the hexagonal and square relati-onship the line 13 will lie at an angle of 15 from the line 14.

The above described relationship places the corners 12 ofthe socket 8 at a point inclined 15 away from the position where there would be a minimum thickness of metal between such corners and the most adjacent point of the circumference of the screw head as would be the case, for example, if the diagonal 13 through the corners 12 lay on the line 14.

The screw, of course, has the usual shank 15 provided with threads 16, the nature and pitch of the threads depending on the intended use of the screw.

In forming the screw, the head 2 is for-med in a two stage operation in which a length of wire rod is delivered a first blow at one end to upset metal at such end to form the ultimate head, then a sec-0nd blow is delivered in which single blow the socket 8 is formed and simultaneously the final hexagonal head shape is obtained.

Thus, in forming the head, the head is blanked and finally shaped by cold working at room temperature to elfect a cold working and strengthening of the head while at the same time affording extremely economical manufacture.

The basic circular configuration 5 corresponds substantially to but may be slightly smaller than the size of the head required for the socket 8 in a circular headed screw. In the hexagon screw illustrated the excess of metal beyond the circular configuration is provided almost entirely at the corners 17 to build up the hexagonal shape. By virtue of the relationship of the socket 8 and the hexagonal head 2 use is made of the metal build up at the corners 17 to increase the wall thickness of the screw head at the socket corners 12 by virtue of their displacement from the line 14, thus allowing for a somewhat smaller circular configuration 5 than would be required in the ordinary round headed screw to provide the requisite socket wall thickness at the socket corners. In use, the screw can be driven by means of an appropriate square cross-section bit without danger of tool slip off and the requisite driving torque may be developed without danger of head splitting. At the same time, the screw can be either tightened or removed by a wrench or pliers without danger of head buckling. Further, the additional feature of providing for removal or tightening by means of a wrench or pliers is achieved Without requiring an excessively large head.

While the preferred embodiment of the invention has been illustrated, it will be understood that variations in the details of construction may be made without departing from the spirit of the invention and the scope of the appended claim.

What I claim is:

A screw having a hexagonal head provided .with a square socket, said head being bevelled at the top and bottom to provide six flat sides meeting at six apices around the head, said sides being generally arcuately bounded at the top and bottom and of increasing axial depth from a minimum at the said apices to a maximum at their mid points, one pair of the sides of the square of the socket being substantially bisected by a line joining one opposing pair of said apices and the other pair of sides of the square of the socket being substantially parallel to a pair of sides of the hexagon of the head mid way between said last mentioned pair of opposing apices, each corner of said square socket being displaced 15 from the next adjacent right bisector of opposing pairs of sides of said hexagonal head.

References Cited by the Examiner UNITED STATES PATENTS 641,191 1/1900 Champion --9 1,066,253 7/1913 Cornelius 859 2,093,646 9/ 1937 Purtell. 2,631,624 3/ 1953 Wright 85-45 2,914,984 12/ 1959' Ansingh 8545 3,182,342 5/1965 Kolec et a1 10-7 FOREIGN PATENTS 436,03 6 4/1927 Germany.

1,476 4/1875 Great Britain. 357,468 9/ 1931 Great Britain. 561,452 5/ 1944 Great Britain.

CARL W. TOMLIN, Primary Examiner.

EDWARD C. ALLEN, Examiner.

M. PARSONS, JR., Assistant Examiner.

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