Abstract: A pivotal jawarm for a compression tool has opposite sides, a pivot pin opening therethrough, longitudinally opposite ends on longitudinally opposite sides of the opening, and inner and outer edges between the ends and on laterally opposite sides of the opening. A stress concentrator comprising aligned recesses in the opposite sides of the jawarm extends from the inner edge toward the pivot pin opening and provides a failure point at the inner edge for consistently initiating a fatigue crack at the failure point and fracture of the jawarm from the failure point to the pivot pin opening.

Abstract: Apparatus for roll grooving thin wall pipe comprises a housing supporting a drive roll and an arm pivotally mounted on the housing and supporting a grooving roll. A feed screw between the housing and arm provides for pivoting the arm to displace the grooving roll radially toward and away from the drive roll, and a release arrangement between the feed screw and arm is operable to release the arm from the screw to protect the screw from damage. The feed screw is mounted on the housing and arm by a double pivot arrangement. Self-tracking during a roll grooving operation is provided by dimensionally different knurling on axially opposite sides of the rolling groove of the drive roll and/or by inclining the axis of the grooving roll relative to the axis of the drive roll and/or by tapering the rolling surface on the rolling projection of the grooving roll and/or by supporting the axially outer end of the drive roll against deflection.

Abstract: Apparatus for roll grooving thin wall pipe comprises a housing supporting a drive roll and an arm pivotally mounted on the housing and supporting a grooving roll. A feed screw between the housing and arm provides for pivoting the arm to displace the grooving roll radially toward and away from the drive roll, and a release arrangement between the feed screw and arm is operable to release the arm from the screw to protect the screw from damage. The feed screw is mounted on the housing and arm by a double pivot arrangement. Self-tracking during a roll grooving operation is provided by dimensionally different knurling on axially opposite sides of the rolling groove of the drive roll and/or by inclining the axis of the grooving roll relative to the axis of the drive roll and/or by tapering the rolling surface on the rolling projection of the grooving roll and/or by supporting the axially outer end of the drive roll against deflection.