Tool driving or impacting – Impacting devices – Hammer head comprises plural parts or diverse materials
Patent
1980-05-05
1982-09-21
Reynolds, Wm. Carter
Tool driving or impacting
Impacting devices
Hammer head comprises plural parts or diverse materials
173DIG2, 227156, B25D 1706
Patent
active
043502148
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a ram block for driving piles and the like into the ground.
Generally, conventional ram blocks are made of cast iron and are short and thick in shape. These cast iron ram blocks provide a short impact wave in the pile, but theoretically a long impact wave is aimed at, which means that it is desired to have a long duration of the period during which the pile is exposed to a force from the ram block, at the expense of a lower force.
The usual way of extending the impact wave in the pile is to use thick resilient and also damping shims between the ram block and the pile, and usually these shims are made of wood but also Nylon shims are used. With such a shim an equilization of the force is thus obtained so that the impact wave expressed as the force over the time will be more rectangular and not exponential as when the ram block is allowed to hit the pile directly. However, these conditions which are more favourable as such are associated with some energy loss in the blow, which may result in the shim getting charred.
The ideal condition would be to construct the ram block with the same length, the same cross section and the same weight as the pile to be driven, i.e. the blow should be effected by means of a pile which is substantially identical with the pile to be driven, but this leads to an impractical construction of the ram block.
Ram block constructions have been proposed previously, which provide a more favourable impact wave than the cast iron ram block and do not involve the drawbacks associated with the use of shims, but these constructions proposed previously wherein mechanical springs or gas springs are used are much more complicated and moreover are exposed to heavy wear when being used.
Furthermore, ram blocks have been constructed with a mass of lead or other damping material enclosed in a steel body in order to obtain thereby some attenuation of the oscillations.
The invention is based on the combination of a steel body and lead or similar material for the object of providing a ram block which is of a simple and sturdy construction and does not include springs or movable parts and which provides, at a relatively low sound level, a long impact wave such that one can let the ram block fall from a greater height without the force being so great that there is a risk of the pile being broken to pieces. Thereby the ram block will drive the pile more effectively.
For this purpose there is provided according to the invention a ram block for driving piles and the like into the ground, comprising a steel body having lead or similar material enclosed therein, with the characteristics appearing from claim 1.
In order to illustrate the invention an embodiment thereof will be described in more detail below, reference being made to the accompanying drawings in which
FIG. 1 is a diagram illustrating the impact wave and the penetration when using a ram block of a prior art construction having exponential impact wave,
FIG. 2 is a perspective view, portions being broken away, of a ram block according to the invention, and
FIG. 3 is a diagram corresponding to that of FIG. 1 relating to the novel ram block according to the invention.
In FIG. 1 the force obtained by means of a ram block of a prior art construction is plotted over the time as a graph A the force F in Mp being indicated on the vertical axis and the time T in ms being indicated on the horizontal axis. Along the same time axis a graph B is plotted, which relates to a ram block of a prior art construction and indicates the velocity V in m/s of the pile being driven, said velocity also being indicated along the vertical axis. As will be seen, the graph A has the appearance characteristic of an exponential impact wave. It is desired to achieve an equilization of the force over the time such that the graph will obtain a more rectangular form, and this is achieved by means of a ram block according to FIG. 2.
The novel ram block according to the invention, disclosed in FIG. 2, comprises an inner steel cylinder 10 and an outer
REFERENCES:
patent: 1167975 (1916-01-01), Burlingham
patent: 2787984 (1957-04-01), Wahlsten
patent: 3570609 (1971-05-01), Wise
patent: 4132108 (1979-01-01), Hogenhout
Lund Hydromaskin AB
Reynolds Wm. Carter
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