Cutlery – Cutting tools – Saw
Patent
1993-06-18
1995-04-18
Payer, Hwei Siu
Cutlery
Cutting tools
Saw
30390, B27B 900, B23D 4516
Patent
active
054067103
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a hand circular saw.
More particularly, it relates to a hand circular saw which has a saw blade swivellable on a support plate by means of a rocker about a swivel axis, and has a splitting wedge which is held on a splitting wedge carrier and by means of a guide device is swivellable about the axis of the saw blade.
From DE-C-28 54 369 (GB-B-800 625) a hand circular saw of this type is known. This saw is provided with a guide device for the splitting wedge and the casing of the hand circular saw. Together with the rocker carrying the saw blade the guide device forms a four-bar lever parallelogram. It holds the splitting wedge and the casing of the hand circular saw parallel to the support plate. If the rocker is swivelled, the splitting wedge and the casing of the hand circular saw follow it without changing the angular position.
Splitting wedges engage in the kerf formed in the workpiece during sawing. They maintain the distance between the halves of the workpiece, guide the rotating saw blade in a stable manner, and cover it. Sawing is thereby facilitated and the risk of injury is reduced. Splitting wedges are a legal requirement for circular saws. For reasons of working safety they must be permanently connected to the saw.
Plunge-cut or cross-cut saws are an exception; these can be lowered onto the workiece which is to be sawn. When the starting cut is made there is no room for the splitting wedge because no kerf has yet been made, so that before cutting starts the splitting wedge must be removed or be able to be uncoupled, through resilient suspension, from the swivelling movement of the rocker, as shown, for example, in the abovementioned patent specification.
A disadvantage of this guide device, which in itself is accurate and reliable, is constituted by the four joints, which are subject to wear. The joints are exposed to considerable shocks and the action of dust. In addition, the known guide device limits the swivelling angle of the hand circular saw and guidance becomes less accurate as the position of the rocker becomes steeper.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a hand circular saw, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a hand circular saw of the above type, in which the guide device is formed as a tension-transmitting drive.
When the hand circular saw is designed in accordance with the present invention, it has in comparison therewith the advantage of a guide device which has a lighter and simpler construction and takes up little space, and which is particularly robust and requires little maintenance. Of the four joint points previously needed, two are eliminated. In addition, the swivelling range of the rocker is no longer limited. Guiding over the entire swivelling range is uniformly accurate. New working and application possibilities are thereby achieved.
In accordance with a further feature of the present invention, the guide device includes two rollers having the same diameter and carrying a tension-transmitting means in form of a rollable V-belt. The rollers can be mounted rotatably. The first roller an be rotatable against the spring force about the swivel axis, or it can be lockable. The second roller can be held non-rotatably on the splitting wedge, for example with interposition of a resilient member. The tension-transmitting means can be formed as belts, changes, cables, spiral springs and the like.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF
REFERENCES:
patent: 2722246 (1955-11-01), Arnoldy
patent: 2737985 (1956-03-01), Utz
Payer Hwei Siu
Robert & Bosch GmbH
Striker Michael J.
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