US 3,990,351 AGranted

Pneumatic impact device

AssigneeAtlas Copco Aktiebolag

InventorBertil Waldemar Sundin

Life of this patent

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Abstract

A pneumatic impact device comprising a housing, a drive piston and a piston rod. At the forward end of the piston rod there is attached a tool intended for metal working like punching, cropping or forging. The housing contains a drive chamber, an air charge chamber, a reverse chamber and a retard chamber. The piston rod is provided with two forward-facing, annular shoulders one of which constitutes a reverse piston for working in the reverse chamber and the other a retard piston for working in the retard chamber. For being protected from impact strains, the drive piston is longitudinally displaceable relative to the piston rod. During the working strokes, the drive piston cooperates with a backwardly facing shoulder on the piston rod, but just before the latter reaches the point where the tool hits the billet to be worked, the drive piston is stopped in the drive chamber and is thereby separated from the piston rod shoulder.

Claims14

Dependent claims

A pneumatic impact device comprising:

a cylinder housing (1) having a front end wall;
a drive chamber (3) in said cylinder housing (1);
inlet (21) and outlet (22) openings in said drive chamber (3) for motive pressure air;
a drive piston (7) provided with a large driving area, said drive piston (7) being reciprocably guided within said drive chamber (3);
a piston rod (8) adapted to carry and apply impacts via a working implement (9);
power-transmitting abutting means (12) on respectively said drive piston (7) and said piston rod (8) for transferring a driving force from said drive piston (7) to said piston rod (8) during a working stroke of said drive piston (7) so as to cause said piston rod (8) to deliver impact energy against an object when in an impact position;
said piston rod (8) being freely displaceable over a given range relative to said drive piston (7) towards said impact position;
and
said pressure air outlet opening (22) of said drive chamber (3) being located so as to be covered by said drive piston (7) during the last part of the working stroke thereof to define a closed air cushion maintaining means between said drive piston (7) and the front end wall of said drive chamber for retarding movement of said drive piston (7) and thereby disengaging said abutting means before said piston rod (8) reaches said impact position.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 05/529,908Filed 5 Dec 1974 · division
Priority: SW 3038/7210 Mar 1972
Granted: 9 Nov 1976
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

B25D 9/00
Portable percussive tools with fluid-pressure drive, i.e. driven directly by fluids
Y10T 83/8772
Means to drive or to guide tool: one tool edge of tool pair encompasses work [e.g., wire cutter]
Y10T 83/8827
With simple rectilinear reciprocating motion only: means to vary force on, or speed of, tool during stroke
Y10T 83/8858
With simple rectilinear reciprocating motion only: fluid pressure actuated