Pneumatic-hydraulic tool, preferably for blind riveting

USRE31957E · kind E · reissue

Inventor

• Lars-Eric Olsson · Arvika, SE

Key dates

• Filing date: Mar 15, 1983
• Grant date: Jul 30, 1985
• Expiry date: Mar 15, 2003

Classification

• Technology area (CPC —): General

Abstract

A pneumatic-hydraulic blind riveting tool comprises on the one hand a hydraulic working piston (25) in a hydraulic cylinder (27) cooperating with a chuck, and on the other hand a pneumatic power piston device (50) in an air cylinder (51) adapted to produce a working pressure in the hydraulic medium by means of a plunger (49). The working piston is adapted to be fed forwards in the hydraulic cylinder a number of steps during each working cycle, and means are provided to cause the power piston device to execute a corresponding number of stroke cycles, each of which includes a forward and return piston stroke. The working piston is adapted to be fed forward one step on each piston stroke. A valve (31) in a plunger passage (29) prevents hydraulic medium from retreating in the plunger passage during the return movement of the plunger. Instead, the plunger passage is filled with hydraulic medium from a reservoir (69) during the backward movement. When the working cycle is completed, an oil return passage (30) is opened. Through this, the hydraulic medium is returned to the reservoir from the hydraulic cylinder while the working piston returns to the initial position. The power piston, th…