Cutting – Rotatable disc tool pair or tool and carrier – Carrier for rotatable tool movable during cutting
Patent
1998-12-28
2000-10-03
Peterson, Kenneth E.
Cutting
Rotatable disc tool pair or tool and carrier
Carrier for rotatable tool movable during cutting
83582, 83614, 83912, B26D 118
Patent
active
06125732&
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to a letter opener with a round knife.
2. Description of the Related Art
An extremely wide variety of letter openers which produce a waste strip while opening an envelope are known from the literature. In this regard, reference can be made merely by way of example to the device for opening envelopes described in CH-A-660,571. In openers of this type, waste is produced, which must be disposed of. In addition, the content of the envelope can also be cut when the envelope is slit open.
Devices are also known which open an envelope without producing any waste. In the machines described in U.S. Pat. No. 4,419,915 and in EP-A-703,097, the envelope is carried by transport devices (belts and similar means of conveyance) past a knife mounted permanently in a housing. Machine designs of this type are complicated and expensive. In addition, there is often the danger that, because of the cutting moment and the transport or braking forces acting at a different point on the letter, the letter can be rotated or upended during the cutting process.
SUMMARY OF THE INVENTION
It is therefore the task of the invention to propose a letter opener of simple design which can be produced at favorable cost and which causes no problems with respect to the relative motion between the letter and the knife. It is also to be possible to start the opening process without the usually tedious task of aligning the letter with the blade as known from many letter openers and without the delicate job of inserting the edge of the letter into a feed slot. In addition, with a properly designed knife, it is to be possible to open the letter without the production of waste. "Waste" is understood here to mean parts of the envelope material, e.g., long strips, which are larger than the dust particles which are inevitably formed by cutting. A goal of the invention is also to provide a letter opener which can be operated by hand.
This task is accomplished by the knife being mounted in a knife housing, which can be moved by hand or driven by a motor along a rail, where a pretensioning (biasing) force acts between the knife and the rail or where means are provided to produce this pretensioning (biasing) force.
Thanks to the pretension between the knife and the rail, production tolerances involving the knife and the knife housing as well as the guide rails and the pressure roll are compensated. The knife always acts with essentially the same force on the letter. As shown in the dependent claims, this pretensioning force can be easily realized in a manner which is very simple in terms of design and which nevertheless operates reliably, e.g., by means of spring-loaded pressure rolls, which act on a shoulder of the round knife. The knife housing, which is provided with a grip, for example, can be slid down the rails without the need to exert very much force, and the letter to be opened can simply be laid freely from above against the lower rail, which simultaneously serves as a stop.
Of course, the knife slide can also be driven by a motor, acting by way of, for example, an additional toothed rack or a toothed transport belt; the motor itself can either travel along with the slide or be mounted in a stationary position (no detailed description of these variants is provided, because in our opinion solutions of this type are familiar to any expert in the field). In summary, a letter opener designed in accordance with the invention is characterized by few parts; a low-cost, compact design; and, thanks to the frictionless rolling motion, by small drive or feed forces. This design also allows an attractive, functional appearance, so that the letter opener also becomes highly suitable as a gift or promotional item.
BRIEF DESCRIPTION OF THE DRAWING
In the following, an embodiment of the letter opener according to the invention is described in greater detail on the basis of the attached figures:
FIG. 1a shows a cross section through the knife housing and the letter support sur
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