US2124616A - Screw socket - Google Patents

Description

uly 6, 1938. A. E; GRANT 2,124,616

SCREW SOCKET Filed June 29, 1936 ATTORNEY Patented July 26, '1938 1 UNITE-b 2,124,616 SCREW SOCKET Albert E. Grant, New York, N. Y., assignor to Albert T. Otto & Sons, Inc., New York, N. Y.

Application June 29, 1936, Serial No. '87,880

2 Claims.

My invention relates to electrical screw sockets of the type adapted to receive a standard lamp or screw plug and, more particularly, to the screw threaded contact shells forming a part of such devices.

It has been usual to form the tubular contact shells in lamp sockets by drawing them in a die from fiat metal, the resulting structure comprising a thin tubular member having the walls thereof corrugated todefine a thread for receiving the base of a lamp or a male threaded plug member.

I have found that because of the substantial tolerances required, the male threaded member of the lamp or plug frequently does not obtain a proper connection within the socket until the end of the plug member abuts the central socket contact and is screwed tightly thereagainst to draw the threaded portions into close contacting relation. Thereafter, if for any reason the thread pressure is reduced, as by jarring or vibration, the central contacts Within the socket are not held firmly together, with the result that arcing between the central contacts is common and frequently the electrical connection is broken entirely.

It is the principal object of my invention therefore to provide a screw contact shell for lamp sockets in which the male plug member will be embraced and clasped in close contacting relation at all times thereby holding the male member in the socket in intimate contacting relation.

Another object is to provide a screw socket shell for electric lamps having the foregoing advantages which may be manufactured at low cost and employed in place of the standard shells now in general use. Referring to the drawing which forms a part of this specification, I

Figure 1 is a perspective view of a screw socket contact shell embodying the features of my invention.

Figure 2 is an elevational view, partly in section, showing a lamp socket embodying my improved screw shell.

Figure 3 is a view similar to Figure 2 illustrating the close contacting relationship of the parts when a lamp is connected in the socket.

My improved screw socket shell comprises a threaded tube ID of resilient metal obliquely split from its top to its bottom at H in the direction of the thread. The lower end of the shell is flared outwardly at l2 to facilitate reception of a lamp or other male threaded contact member and the upper edge margins are bent inwardly at right angles to form a fiange I3. A hole is formed through the flange at IE to receive the usual stud or staple whereby the shell may be secured in the lamp socket 20 and connected with 7 one of the current supply wires 2| thereof, the other wire being connected to the contact 3| located centrally in the socket recess.

The helical thread I4 is of proper pitch to receive the male threaded contact member of a standard lamp, fuse, or screw plug, but the normal diameter of the shell is slightly less than the diameter of such male member and less than the internal diameter of the standard socket in which it is carried, substantially as shown in Figure 2. However, when the somewhat larger male threaded base 40 of a standard lamp is threaded into the socket, the split shell is expanded against the resistance inherent in the resilient metal of which it is formed, being forced against the insulated socket walls 32 and securely embracing and clasping the male member in tight 20 contact, the central contacts 3| and 4| being held in firm abutment at all times.

The angular disposition of the slot ll intersecting the convolutions of the thread I4 permits contact between the shell and the male member over the full circumference of the lat- 'ter.

When the lamp or plug is removed from the socket, the resilient shell resumes its normal undersized condition, so that it may be reused to obtain all of its advantages a larger and indeterminate number of times.

Screw socket shells may be manufactured very economically in my improved form by drawing an undersized shell from suitable spring metal in the usual manner of manufacture and thereafter splitting it. However, I prefer to make the device from strip metal, each strip section having its end edges extending obliquely to the strip and parallel with each other, the strip being curled into tubular form with its end edges brought into close adjacence to define the angular slot ll. When so made, the thread M, the flare l2 and the flange l3 may be imparted to the strip by die elements carried in the rolls employed to curl the strip into its tubular form.

However made, the device will be found to provide improved spring pressed contact and good mechanical connection.

I claim:

1. In a screw socket, a housing, a contact shell comprising a tube of resilient metal threaded to receive a standard male threaded contact memher, said tube having normal diameter less than said member and being split entirely theretube is adapted to be expanded by a male mem 5 per and to resiliently clasp said member in close contacting relation.

2. In a screw socket, a housing, a contact shell comprising a tube of resilient metal threaded to receive a standard male threaded contact member, said tube having normal diameter less than said member and being obliquely split entirely therethrough transversely of its thread,

said tube being secured in the housing at its inner end adjacent and to one side of the split 5 therein whereby the tube is adapted to be expanded by a male member and to resiliently clasp. 7 said member in close contacting relation.

ALBERT E. GRANT.

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