Tools – Hammer – Having shock absorbing means
Patent
1998-03-11
1999-11-30
Meislin, D. S.
Tools
Hammer
Having shock absorbing means
B25D 112
Patent
active
059922702
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns a shock absorbing hammer, comprising a shaft and a hammer head being provided with a shock absorbing material, e.g. in the form of a rubber material, a hydraulic cushioning material or the like, the purpose being to dampen the rebound force and vibrations imparted to the shaft when the hammer head hits an object during a swinging motion of the hammer.
2. Description of the Related Art
There are many examples of hammers of this general kind, see e.g. U.S. Pat. No. 2,451,217, U.S. Pat. No. 3,172,438, U.S. Pat. No. 4,085,784 and SE-B-462,616. The last-mentioned document discloses a hammer, wherein an end portion of the shaft is mounted in a recess in the hammer head so as to permit a limited pivotal movement, being damped by a shock absorbing material, in one angular direction from a rest position when the hammer head strikes an object during a swinging motion of the hammer, whereas mutual movement in the opposite angular direction from said rest position is inhibited. Accordingly, the hammer can either be used in the normal way for striking an object, e.g. a nail, with the hammer head or, alternatively, for withdrawing a fastener, e.g. a nail, by means of a claw portion at the back of the hammer head.
However, this known hammer is relatively complicated in its structure, namely with radially projecting lugs formed at the shaft end portion in order to ensure a direct surface contact between the shaft and the hammer head inside the recess, the latter being substantially parallel to but wider than the shaft end portion. In some embodiments there are also internal, especially adapted recess portions, in addition to a simple cylindrical bore in the hammer head, which make the production thereof even more complicated and expensive.
SUMMARY OF THE INVENTION
A primary object of the present invention is to provide a shock absorbing hammer of the kind defined in the preamble of claim 1 which has a simple structure and is inexpensive to manufacture and which provides an effective shock absorbtion.
This object is achieved in that the shaft end portion and the recess in the hammer head are both cylindrical, the cylindrical recess in the hammer head being obliquely inclined in relation to the cylindrical shaft end portion, so as to provide wedge-like upper and lower recess portions, which accommodate the shock absorbing material and permit a limited pivotal movement in one angular direction, and in that, in the rest position, the shaft end portion is in surface contact with the inside wall of the obliquely inclined cylindrical recess at diagonally opposite locations directly, i.e., without the intermediary of said shock absorbing material, whereby mutual movement in the opposite angular direction is inhibited.
The manufacture of a hammer according to the invention is simple. Thus, it is sufficient to make a downwardly inclined bore hole in the hammer head, as seen from the side of the shaft, and to insert the cylindrical shaft end portion, which has a smaller diameter, into the bore horizontally, so that the shaft end portion makes direct contact with the walls of the bore adjacent to the front end of the shaft, normally near the bottom of the hole, and adjacent to the opening of the bore, whereby the shaft end portion, and the central axis thereof, will extend at an angle, normally 3.degree.-10.degree., preferably about 4.degree., relative to the bore axis.
In this way, there will remain a lower recess portion with increasing vertical thickness from the location of contact near the opening of the hole to the bottom thereof, and an upper recess portion with increasing thickness in the opposite direction. These recess portions are shaped somewhat like a wedge, at least as seen in a vertical section, and are filled with a shock absorbing material. Because of this wedge-like configuration, the dampening and shock absorbing power of the shock absorbing material will be uniform and effective along the full length of the shaft portion inser
REFERENCES:
patent: 2451217 (1948-10-01), Heinrich
patent: 3172438 (1965-03-01), Gianelli
patent: 4085784 (1978-04-01), Fish
Brok Hans
Hedelin Joakim
Hultafors AB
Meislin D. S.
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