Rapid installation fitting for plain end pipe

Claim 1

A pipe fitting comprising: (a) a wall defining a metal pipe end receiving socket with a pipe cradling interior surface, (b) a screw threaded bore extending through said wall and having an axis directed toward said interior surface, (c) a locking device comprising a shaft body having a head at one end and at least one cutter at the other end, said shaft body being externally screw threaded and engaged in said threaded bore, (d) said head being greater in diameter than said shaft body and adapted for rotating said shaft and thereby spirally advancing said cutter toward said interior surface, said wall forming a shoulder aligned with said head and forming a stop to limit the travel of said head toward said interior surface, (e) said cutter comprising a projection directed from said body other end toward said interior surface and having intersecting faces forming a metal cutting edge, (f) said cutting edge being spaced from the axis of said shaft and positioned in a cutting attitude when spirally advanced toward said interior surface, (g) said cutting edge having a rake angle configuration such that a limited cutting penetration rate is achieved under a predetermined pressure range and travel speed along a pipe end surface, (h) the thread pitch of said bore and shaft being such that said cutting edge, upon rotation of said shaft in said bore, advances at a rate greater than said cutting penetration rate such that said pipe is deformed and urged against said socket interior surface at a location generally diametrically opposite said cutter, whereby said projection cuttingly penetrates into the pipe surface simultaneously with urging the pipe into cradling contact with said socket interior surface, thus firmly locking the pipe end in said fitting, and (i) the positioning of said stop being such as to allow said cutter to partially penetrate the pipe but preventing said cutter from passing through the pipe.