Tool driving or impacting – Impacting devices – With impact cushioning means
Patent
1995-08-28
1998-08-25
Smith, Scott A.
Tool driving or impacting
Impacting devices
With impact cushioning means
173 15, 1731621, B25D 1724
Patent
active
057974632
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a pneumatic hammer comprising a housing, which is provided with a handle, an operating cylinder, which is resiliently supported within the housing, and a tool holder for receiving a tool.
In pneumatic hammers, the reversible supply of compressed air to the operating cylinder, the reciprocation of the piston in the operating cylinder, the impacts of the piston on the tool, the rebound of the tool and the like actions give rise to a generation of intense noise and strong vibration, which in the absence of countermeasures will be dangerous to health. To suppress noise, it is known to design the housing as a sound absorber. Whereas that measure in conjunction with a corresponding sound insulation of the source of compressed air will result in an appreciable alleviation of the noise, a satisfactory damping of vibration has not yet been achieved. Various spring and rubber elements have been used in pneumatic hammers for damping vibration by cushioning the operating part of the hammer relative to the handle. In most cases a plurality of damping inserts are provided in series between the tool and the handle. Such damping inserts and spring elements have a soft spring characteristic to ensure a corresponding damping action so that the operating part is movable relative to the handle. For this reason the operator of the pneumatic hammer is deprived during his work of feeling for the tool and the workpiece. This is so because as the pneumatic hammer is forced against the workpiece the handle will yield to a relatively large extent before the desired pressure is applied, and the disengagement of the tool also requires a retraction of the handle to a large extent until the tool proper has disengaged the work-piece and then follows the retraction of the handle. The inconsistent requirements for a tool which is rigid so that it can effectively be guided, on the one hand, and for an appreciable damping of vibration by a soft cushioning, on the other hand, have previously necessitated a rather unsatisfactory compromise between the ability to guide the hammer and the vibration damping.
2. Description of the Prior Art
DE-B 10 18 819 discloses, for instance, a pneumatic hammer which is of the kind described first hereinbefore and in which the tool receptacle is constituted by the operating cylinder, which is longitudinally guided in the housing, and shocks are absorbed in that the operating cylinder is resiliently clamped in the transitional region between the housing and the handle and an elastic ring for supporting a flange of a tool is provided at the lower end of the housing. Because the tool receptacle is integrated in the operating cylinder, that operating cylinder will necessarily be forced against the housing when transverse forces occur and the operating cylinder will then be seized in its longitudinal guide so that any damping action will be eliminated. Besides, because the operating cylinder is suspended adjacent to the handle, it is inherently impossible to use the housing as a means for assisting the damping of the reaction forces of the operating cylinder.
SUMMARY OF THE INVENTION
It is an object of the invention to eliminate these disadvantages and to provide a pneumatic hammer which is of the kind described first hereinbefore and is simple and robust in design, has good handling properties appropriate for the work to be performed and is also distinguished by an excellent vibration damping.
That object is accomplished by the invention in that the handle, the housing, and the tool holder constitute a rigid unit of construction, the operating cylinder is axially movably guided relative to the tool holder, and the tool holder is provided with tool-damping means, which act opposite to the striking direction. Owing to the provision of said unit of construction the operator of the pneumatic hammer perceives that the connection between the handle and the tool holder has the stiffness required for the desired guidance of the hammer and
REFERENCES:
patent: 2341497 (1944-02-01), Amtsberg
patent: 2949909 (1960-08-01), Macchioni et al.
patent: 3053231 (1962-09-01), Fairchild
patent: 3063508 (1962-11-01), Henry
patent: 3375881 (1968-04-01), Myers et al.
patent: 4072199 (1978-02-01), Wanner
patent: 4102410 (1978-07-01), Ross
patent: 4614241 (1986-09-01), Crover
patent: 5485887 (1996-01-01), Mandanis
Martin Werner
Schabelreiter Johann
Winter Udo
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