Tool driving or impacting – Impacting devices – Selective axial direction of impact
Patent
1986-02-10
1988-03-29
Kazenske, E. R.
Tool driving or impacting
Impacting devices
Selective axial direction of impact
175 19, B25D 900
Patent
active
047337311
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to civil engineering, and more particularly to an air-operated reversible percusive action machine which can find application, for example, in making holes in the ground, and driving into the ground various structural elements, such as pipes.
A special feature of such machines is the provision of a means for reversing its percussive action to retrieve the machines from a blind hole made in the ground or disconnect the percussive action part from the element being driven into the ground.
BACKGROUND OF THE INVENTION
There is known an air-operated percussive action machine (cf., USSR Inventor's Certificate No. 238,424, IPC E 02f 5/18) comprising a cylindrical housing, a hammer having a port and a cavity in its tail portion, a threaded air distribution tube, and a nut provided with passages.
The air distribution tube occupying the interior of the hammer is of stepped configuration. End face edges of the larger step act to control air distribution, i.e., time the inlet of compressed air to the return stroke chamber of the hammer and discharge thereof to the outside. The step of smaller diameter has a threaded portion to connect the air distribution tube to the housing of the machine. By unscrewing the tube from the housing the end face edges of the larger diameter step are displaced to ensure an advance inlet of compressed air to the return stroke chamber, whereby inpacts of the hammer on the front portion of the housing are prevented. Conversely, a delayed exhaust of compressed air causes a longer stroke of the hammer, whereby the impacts are delivered on the rear portion of the housing for the machine to operate in the reverse percussive action mode.
In order to change the percussive action of the machine, it is necessary to stop the delivery of compressed air and screw the tube into the housing. The end face edges of the larger diameter step are therefore moved forward to cause a delayed (as compared with the reverse percussive action) inlet of compressed air to the front working chamber and advanced exhaust thereof to the outside. This determines operation of the machine in the forward percussive action mode, when the impacts are delivered exclusively on the front end of the housing.
The abovedescribed arrangement of the percussive action machine suffers from the following disadvantages:
(a) much time required for switching the machine over from one percussive action mode to the other, since such a procedure involves terminating the supply of compressed air, disconnecting the air-feeding hoses, and turning the tube 10 to 14 revolutions, or repeating these procedures in the reverse successive when changing the percussive action of the machine from the forward to the return travel in the hole;
(b) affected reliability in operation due to that one of the elements of the machine structure, particularly the tube, extends away from the housing, whereby dirt is liabile to plug the threads and jam the machine; and
(c) excessive amount of manual labour for changing the percussive action mode of the machine.
There is also known an air-operated reversible percussive action machine (cf., West German Pat. No. 2,340,751; IPC E 21b 7/00) comprising a housing, a hammer having a port and a cavity in its tail portion to reciprocate inside the housing, a tube having projections and recesses provided at the step of smaller diameter and secured at a flange provided with a hole and grooves, and a lock means with a cable. For reversing the percussive action of the machine it is sufficient to pull the cable, release the lock means, and then to turn the tube so that its projections would align with the grooves of the flange, whereby under the action of compressed air the tube enters the grooves by moving axially.
However, the above arrangement of the machine suffers from a number of disadvantages, among which are;
(a) complicated percussive action reversal procedure due to simultaneously applying a pull force to the cable for releasing the lock means and rotating the air-feeding hos
REFERENCES:
patent: 3727701 (1973-04-01), Sudnishnirov et al.
patent: 3891036 (1975-06-01), Schmidt
patent: 4078619 (1978-03-01), Sudnishnikov et al.
patent: 4221157 (1980-09-01), Schmidt
Bondar Mikhail J.
Kostylev Alexandr D.
Reznikov Igor I.
Tarasenko Vladimir I.
Tkach Khaim B.
Kazenske E. R.
Phan Hien H.
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