Woodworking – Process – Including monitoring of operation
Patent
1992-10-26
1994-12-20
Bray, W. Donald
Woodworking
Process
Including monitoring of operation
83364, 83367, 144242R, 144246R, 144249A, 144117R, 1984642, 198572, 198782, B27C 112, B27B 100
Patent
active
053738799
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase of PCT/DE91/00466 filed May 29, 1991 and based, in turn, upon German National Application P 40 17 991.5 filed Jun. 5, 1990 under the International Convention.
FIELD OF THE INVENTION
My present invention relates to a process for machining blanks made of wood or similar materials, such as plastic or the like, by means of planing machines or the like, wherein by means of a feeding device oblong wood blanks are moved on a bearing or guide surface in a longitudinal direction with respect to themselves, with their frontal end towards a rotating tool, such as a planer head, until the machined front end is seized by an advance roller provided downstream of the tool and is further transported over a reference table.
BACKGROUND OF THE INVENTION
In order to machine wood blanks according to the above process, planing machines, automatic four-edge planing machines, automatic thicknessing machines, automatic profile cutting machines, planing, grooving and keying machines and others are used.
The rotating cutting tools work on the wood blank against its advance direction, so that during the advance the cutting reactions translate into a resistance which has to be overcome. When the front end of the wood blank has passed the cutting tool and has made contact with the first advance roller, then the latter is capable to insure the further advance with its own conveying force, namely with the optimal advance speed required by the machining process.
The known processes have certain problems related to the conveying of the wood blank into the machine, past the rotating tool up to the point of contact with the first advance roller.
Manual feeding is widely used. This procedure requires a certain practice and experience, as well as persistence and concentration of the operator, in order to feed the blanks with the necessary force and at the same time with the required constant advance speed until the front end of the blank reaches the first advance roller. Even experienced operators make mistakes at times, with the result that during the machining process or as the rotating tool is passed, the front end of the wood blank receives chatter marks as a result of the uncontrolled advance speed and the variable contact pressure.
Manual feeding is labor intensive and therefore expensive. At today's state of the art it is acceptable only in a craftsmanship operation. At least the front ends of the wood blanks damaged by chatter marks have to be cut off, since they are unsuitable for further use. So there is more or less waste. However, if the wood blanks have been precut to the desired length, then the finished wood pieces with chatter marks are completely wasted.
As a rule, processing machines for wood blanks also have input rollers, which insure the required advance speed and the constant contact pressure. They are arranged immediately upstream of the rotating tool, opposite the support and guide surface.
In practice the use of input rollers is avoided whenever possible. The rollers are frequently pulled off their shafts, thus being removed. Usually they are arranged at the greatest possible distance from the support and guide surface and secured so that they do not come in contact with the wood blanks under any circumstances. Such operations can only be performed when the processing machine is at a standstill.
The reason for this procedure is that the wood blanks which have been processed with input rollers are usually fraught with irregularities, e.g. they particularly lack the rectilinear precision required for profiles for windows, furniture and so on.
The cause of this lack of rectilinear precision is the relatively high contact pressure of the input roller. However it is unavoidable, since the first cut or the first contact between the rotating cutting tool and the frontal surface of the front end of the wood blank sometimes causes shock or impact-like cutting reactions which, without a strong hold on the blank by corresponding contact pressure o
REFERENCES:
patent: 2985205 (1961-05-01), Mann
patent: 4343209 (1982-08-01), Moelbert
patent: 4457350 (1984-07-01), Finnila
patent: 4583576 (1986-04-01), Rautio
patent: 4907632 (1990-03-01), Reuter
patent: 5285887 (1992-02-01), Hall
Bray W. Donald
Dubno Herbert
Hoffmann & Kuhnhenrich GmbH
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