Tube coupling

Claim 1

A tube coupling comprising a body member adapted to receive and seat the end of a tube, said body member having a camming surface therein; a front collet member having a bore through which the tube extends and a camming surface therein; a rear collet member having a bore through which the tube extends, a radially extending flange on said rear collet member and a frontal projection extending from said flange, said frontal projection having an annular and rearwardly inclined leading face with a radially inner cutting edge and including, as an exterior surface, a first forwardly positioned tapered surface increasing in diameter from front to rear and a second rearwardly positioned tapered surface intersecting said first surface at its forward end, decreasing in diameter from front to rear, and intersecting said flange at its rearward end, thereby to reduce the radial thickness of said projection adjacent said radially extending flange to enable said projection more readily to flex; and a nut slidable along the tube and threadedly engaging the body member to Capture said front and rear collets with said nut, when tightened, being threadedly advanced along said body member, said nut having an internal shoulder to engage said flange to drive said rear collet forwardly, which in turn drives said front collet forwardly until said internal shoulder, said radial flange, said front collet and said body are in end to end abutment precluding further nut advancement, the forward advancement of said rear collet driving said frontal projection on said rear collet against the cam surface in said front collet to cause said frontal projection to flex and drive said cutting edge into biting engagement with the tube, said annular leading face being inclined rearwardly at an angle interrelated to the slope of said cam surface in said first collet, whereby said cutting edge penetrates said tube in a direction substantially radial to the axis of the coupling, when the nut has been fully tightened.