US 819866

Patent Overview — US819866A

Title: Sheet-Metal Joint

Patent number: US819866A

Inventor: John E. Dobson, of Ypsilanti, Michigan

Assignee: Michigan Machinery Manufacturing Company, of Ypsilanti, Michigan, a corporation of Michigan

Application number: US24255405A

Filing/priority date: January 24, 1905

Publication (grant) date: May 8, 1906

Legal status (as listed): Expired – Lifetime; anticipated expiration May 8, 1923 (the source states legal status is an assumption, not a legal conclusion)

Purpose: To obtain a flush joint between sections of sheet metal, formed without brazing or welding, in which the adjoining sections cannot become detached from each other. It is described as particularly designed for metallic rings such as are used in stove construction.

Plain-language scope: Two flat sheet-metal sections (A, B) have complementary teeth (a) and notches (b) on their adjoining edges. The teeth of one section are slipped into the notches of the other so they intermesh and interlock, holding the sections against displacement in the plane of the blank but still permitting disengagement by relative lateral movement. The blank is then bent into a curved cross-section, preferably between dies (C, D). Because this bending is transverse to the line of the joint, the adjoining tooth faces are no longer parallel but lie at an angle to one another, so each tooth locks the others against lateral movement and the sections cannot be disengaged. Where a ring is made, the blank is first formed into a plain hoop with edges joined, then drawn into the curved cross-section. Four claims are presented, covering: complementary teeth intermeshing in different planes and locking the sections from movement in any direction with a joint thickness equal to the tooth thickness; teeth whose opposite edges lie in different planes; interlocked tooth pairs whose planes are out of angle along the joint line; and a joint whose longitudinal line is curved.

Source: https://patents.google.com/patent/[US819866](/patent/US819866)/en

What the excerpt does not establish: It does not establish litigation, ownership transfers, validity, or the content/effect of prior art. Figure text and the Fig. 6 modification are only partially legible; the excerpt does not detail the modified construction or the omitted portions of the cited-by list.