Cutlery – Sheathed – Sliding blade
Reexamination Certificate
1999-06-11
2001-05-22
Rada, Rinaldi I. (Department: 3724)
Cutlery
Sheathed
Sliding blade
C030S286000, C030S293000
Reexamination Certificate
active
06233832
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a razor or utility knife. More particularly this invention concerns such a knife with a retractable blade guard.
BACKGROUND OF THE INVENTION
A standard utility knife has an elongated handle having an outer end and a longitudinally extending flat blade secured in the handle and projecting outwardly from the outer end. The blade has a transverse outer edge and a longitudinally extending side or front cutting edge meeting at a point. Such a knife is useful for opening packages, including cartons and bags, and is typically carried in the pocket or tool belt of the person using it.
In order to protect the user from injury by the cutting edge and point it is known from German patent 3,116,354 and U.S. Pat. No. 4,086,698 to form the handle with a longitudinally outwardly open and longitudinally extending guide slightly offset laterally from the cutting edge of the blade. A longitudinally extending pin has an outer end carrying a bumper or shield and is longitudinally displaceable in the guide between an extended positions with the outer end lying longitudinally outward of the point and a retracted position with the outer end longitudinally inward of the point. A spring is braced between the pin and the handle and urges the pin into the extended position.
The problem with this system is that it is relatively easy to accidentally push in the guard. Thus if the knife is in a pocket and the user reaches in to grab it, the knife or guard can be pushed to retract the guard and allow the blade to come into direct contact with the user or the user's clothing.
U.S. Pat. No. 142,942 describes a similar knife for use by a cobbler. A spring-loaded mechanism is provided in the handle to set the projection of the blade so as to limit the depth of cut, but it does not provide any protection against injury from the blade. The blade can be retracted into the handle or ejected from it by special maneuvers.
Another knife is known from German 3,433,286 which has a U-shaped guard for the blade. This guard, as in German 3,116,354, is spring loaded so it can be pushed back in by careless handling. Thus it provides little real safety for the user of the knife.
In German 3,540,026 there is a pivotal blade guard of elastic material. The guard can be locked in position by a relatively complex maneuver so that it is likely never to be locked, thereby affording little protection to the user.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved utility knife with a retractable blade guard.
Another object is the provision of such an improved utility knife with a retractable blade guard which overcomes the above-given disadvantages, that is which allows the guard to be latched and unlatched relatively easily.
SUMMARY OF THE INVENTION
A knife has according to the invention an elongated handle having a front end, a longitudinally extending flat blade secured in the handle, projecting from the front end, and having a transverse front edge and a longitudinally extending side cutting edge meeting at a point, and a blade guard longitudinally displaceable on the handle between an outer extended position projecting longitudinally outward of the point and a retracted position exposing the point. A guard spring braced between the guard and the handle urges the guard into the extended position. A button is transversely displaceable on the handle between an actuated and an unactuated position and interengageable formations on the button and on the guard prevent movement of the guard from the extended into the retracted position in the unactuated position of the button.
Thus unless the button is actuated, the guard is locked in the outer position. The button can be built according to the invention as a bar extending along a front edge of the knife handle, so that it is automatically depressed and actuated when the knife is gripped in a manner to be used. Simple pressure on the guard will not, however, cause it to retract so that the knife can even be dropped on its tip without danger.
According to the invention the handle is formed with a longitudinally forwardly open and longitudinally extending guide slidably receiving the guard. The guard has an inner end carrying a pawl forming one of the formations and movable by the button between an engaged position of the formations and a disengaged position of the formations. This pawl is movable on the support and the formations of the pawl and handle are directed longitudinally and the pawl is pivotal on the support about a transverse pawl axis. More particularly the pawl has an arm extending longitudinally forward from the axis and formed with the one formation.
The system can be set up as described above so that so long as the button is actuated the guard is free to move back and forth between the extended and retracted positions. To this end the formations extend transversely and the button has a transversely directed surface engageable with the pawl. In addition the button is formed with a longitudinally open notch having a flank forming the one formation and the arm has an end engageable in the notch. A pawl spring braced between the pawl and the handle urges the pawl into a position with the formations longitudinally engageable with each other. A button spring urges the button into the unactuated position. In this system the button is formed of one piece with the notch.
In another system of this invention actuation of the button allows the guard to move into the retracted position, but if the guard moves back into the extended position it locks in place and can only move inward again if the button is released and reactuated. In this system a rocker forming the notch and movable longitudinally on the button has adjacent the notch a surface engageable longitudinally with the pawl in the actuated position of the button on movement of the guard from the retracted to the extended position. A rocker spring urges the rocker toward the pawl and is weaker than the guard spring. Thus the guard spring can overcome the force of the pawl spring for the desired override effect.
The rocker in this embodiment is pivotal on the button, the arm has an outer end engageable in the notch and with the surface of the rocker, and the one formation is between the outer arm end and the transverse pawl axis. The rocker spring is braced longitudinally between the rocker and the button and the guide forms the other formation.
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Messer Gerhard Alarich Ern. Solingen-Wald, E 19792,PA 284071, 5 pages, Aug. 1964.
Dubno Herbert
Martor-Argentax E.H. Beermann KG
Rada Rinaldi I.
Wilford Andrew
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