Tool driving or impacting – Impacting devices – Hammer head driven by spring
Patent
1988-06-16
1989-09-19
Yost, Frank T.
Tool driving or impacting
Impacting devices
Hammer head driven by spring
173134, 173DIG2, 181230, B25D 1712
Patent
active
048672521
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to pneumatic apparatus of the percussive type used in construction, mining, mechanical engineering and metallurgy and has specific reference to single-stroke pneumatic apparatus.
Description of the Prior Art
Single-stroke pneumatic apparatus commonly employed for marking, centre-pricking, marking-off and chiselling off risers are pneumatic hammers. The tool the hammer is fitted with varies with the application. It can be a stamp, a prick-punch, a hobby or a chisel. The tool is supported in a hollow frame with inlet and outlet ports and a striker dividing the frame bore into forward- and working-stroke chambers. A directional flow control is provided on the frame. The source of energy is compressed air fed from a mobile or stationary compressor over a flexible hose. In operation, the compressed air admitted into the chambers of the frame with the aid of the directional flow control manipulated by the operator, causes the striker to reciprocate back and forth axially and deliver cyclewise blows at the end face of the tool. The work done by the tool materializes in any of the following operations depending on the type of the tool: marking, centre-pricking, chiselling or riveting.
The atmosphere at the working place where pneumatic hammers are in use is commonly laden with dust and the operator cannot but stay in such a surrounding. Therefore, the problem of increasing the reliability of the pneumatic hammer is one of great concern.
Known in the art is a single-stroke pneumatic apparatus (cf. USSR Inventor's Certificate No. 781048, IPC B25D 9/14, 1980) comprising a hollow cylindrical frame provided with inlet and outlet ports, and a striker recurrently interacting with a resilient means located at an end face of the frame. The directional flow control is a solenoid-actuated valve operated by a microswitch. The valve made up of three parts lacking a mechanical link with each other is of intricate design. Apart from that, the known apparatus lacks reliability, for dust and other fine particles are sucked into the bore of the frame through the outlet ports when the striker is on a back stroke. The noisy high-velocity exhaust from the apparatus creates trying labour conditions for the operator.
Also known is a single-stroke pneumatic apparatus, i.e. a pneumatic hammer (cf. German Patent No. 671,958, Cl. 87b 2/11, 1939) comprising a hollow cylindrical frame with inlet and outlet ports, a spring-loaded striker forming forward- and back-stroke chambers in the frame bore, a handgrip located wherein is a directional flow control and a tool fixed in the upper end of the frame.
In the known apparatus, the outlet ports are laid out in a way which cannot prevent ingress of dust-laden atmosphere into the frame bore. Therefore, the hammer cannot last long. The noisy exhaust from the apparatus creates trying labour conditions for the operator.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a single-stroke pneumatic apparatus, in which an enhanced reliability and improvements in the service conditions thereof would be ensured by the design of the air-distribution means.
The invention includes a single-stroke pneumatic apparatus comprising a hollow cylindrical frame with inlet and outlet ports, a handgrip attached to the upper end of the frame, a directional flow control located in the handgrip and used to admit compressed gaseous fluid recurrently into the bore of the frame, a striker located in the bore of the frame with provision for reciprocating back and forth so as to divide the bore of the frame into a forward-stroke chamber--admitted recurrently through the inlet ports is compressed gaseous fluid--and a back-stroke chamber, a return spring fitted to the striker at that end thereof which faces the back-stroke chamber, a tool attached to the lower end of the frame, and a shell with holes which surrounds the frame and forms therewith a muffling chamber communicating with the atmosphere via the holes in the shell and w
REFERENCES:
patent: 2128742 (1938-08-01), Fuehrer
patent: 4293045 (1981-10-01), Zeidman et al.
Sudnishnikov Vadim B.
Zelentsov Andrei A.
Institut Gornogo Dela Sibirskogo Otdelenia Akademii Nauk SSSR
Wolfe James L.
Yost Frank T.
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