Cutlery – Sheathed – Pivoted blade
Reexamination Certificate
2001-03-22
2002-08-27
Rachuba, M. (Department: 3724)
Cutlery
Sheathed
Pivoted blade
C030S152000, C030S162000, C030S154000
Reexamination Certificate
active
06438849
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to utility knives and more specifically to a spring loaded utility knife wherein the blade is constantly biased toward a retracted position so that upon the removal of manual pressure holding the blade in an exposed cutting position, the blade is automatically retracted to a non-exposed position under the bias of the spring.
2. Discussion of the Related Art
A number of utility knives have been proposed which have blade is arranged within a housing and arranged to project by an amount suitable for cutting paper, tape and the like. While these type of knives have found considerable utility, there has been a problem that the blade does not automatically retract upon the cutting operation being completed and requires that the operator take steps to have the blade move back within the housing of the device. One such device is disclosed in U.S. Pat. No. 5,813,121 issued on Sep. 29, 1998 in the name of Gringer. This device is such as to feature a side mounted slider which projects out of one side of the handle or housing and includes a series of positions in which the blade can be locked in a projected state. Due to the arrangement of the thumb piece being located on one side of the housing, this arrangement is limited to use by right handed people. Further, in the embodiments wherein a serpentine spring is used to retract the blade upon a lock mechanism is released, the spring, the blade carrier, the lock mechanism and the thumb piece are all integrally formed. The molding process required to achieve the production of this element is, of course, complex adding to the production cost. It further prevents the position/orientation of the blade carrier within the handle or housing from being varied to permit the use of differently shaped cutting blades and limits the degree to which the amount of projection of each blade can be adjusted in accordance with the task in hand.
U.S. Pat. No. 5,581,890 issued on Dec. 10, 1997 in the name of Schmidt, discloses a utility knife which permits the blade to be retracted back into the housing automatically upon the removal of manually applied pressure on a thumb piece. Nevertheless, this arrangement is provided with a rack on the interior of the housing and a projection on the blade carrier which is adapted to engage the rack in a kind of ratchet type of arrangement. This of course inhibits the change of the blade carrier orientation within the housing and thus prevents the use of a variety of different types of blades in the same device.
A further drawback that both of the above arrangements suffer from is the manner in which the two halves of the handles interconnect with one another. While the arrangement in U.S. Pat. No. 5,813,121 attempts to render the halves readily disengageable from one another via the provision of a latch member which is mounted on a flexible portion and arranged to bent via the application of a digit such as the operator's thumb, the arrangement tends to be relative fragile and apt to fail after a large number of operations. The arrangement disclosed in U.S. Pat. No. 5,581,890, on the other hand, is such as to use a barbed member which snaps into a locking position once inserted sufficiently through an aperture formed in the other half. In this arrangement the ability to separate the two halves has not been given much consideration tends to be difficult to separate once they are engaged with one another.
Accordingly, there exists a need for a utility knife which is readily separable into its two halves, which has an engaging mechanism which is robust and which is not apt to fail after a relatively small number of operations, and which allows for a variety of different blades to be mounted and used in accordance with the desires of the user.
SUMMARY OF THE INVENTION
The present invention therefore is such as to feature a housing which has a unique engagement arrangement which is both robust and which allows with a simple press of the thumb, the two halves to be force apart to a state where disassembly of the knife is facilitated and quick and easy blade replacement/adjustment is rendered possible.
The present invention further features a blade carrier which is disposed in the housing and which can be, once the housing is popped open, adjusted with respect to an engaging portion formed on a thumb pieces to adjust the maximum amount of blade projection, or inverted so as to accommodate a different type of blade and allow for different cutting operations.
A further feature of the present invention is the ability to store spare blades within the housing, so that when the two halves are separated, switching from one type of blade to another is sped up in that the new and desired blade is immediately on hand and as such no searching about for the same is necessary.
Yet another feature of the present invention is the provision of a finger guard which is located on the lower edge of the housing. This guard allows the operator to place his or her index finger in a position wherein it is prevented from accidentally sliding forward toward the blade when projected.
In brief, the present invention is such that, in order to automatically retract the blade after cutting, a flat serpentine spring is integrally formed with a thumb piece which is slidably received in a slot formed along the upper edge of a housing/handle. The housing has a finger rest projection on the lower edge to facilitate cutting while the blade is projected with the thumb. The two halves of the housing snap together using a block-like projection formed on one half, and a pair of tabs formed on the other. The tabs, which are resilient, slide along the sides of the projection until recesses on each of the side of the projection are reached. Inwardly extending ridges on the ends of the tabs enter the recesses to provide a click lock. An aperture between the tabs allows pressure to be applied to the top of the projection to separate the two halves for blade reset/re-adjustment. The blade carrier, which is adapted to support two different types of blades, is slidably mounted in the housing so that it and the thumb piece are free of detents or click-locks. The carrier's upper and lower edges have a number of apertures to permit setting in different orientations and adjustable positioning with respect to an engaging projection on the base of the thumb piece. This, in combination with the ability to set at least one of the blades in a plurality of different positions on the carrier, allows a high degree of blade projection adjustment.
More specifically, a first aspect of the present invention resides in a utility knife including a manually grippable housing comprised of first and second halves. The first and second halves cooperate to define an enclosed space therebetween and include connection means for permitting the first and second halves to be releasably connected to one another comprising: a) a shaped projection which is rigid with the first half; and b) a pair of resilient tabs formed on the second half, the pair of tabs extending along opposed sides of the projection to frictionally engage the opposed sides of the projection and hold the first and second halves together.
The above-mentioned connection means includes recessed portions formed in the sides of the projection in which ridge portions on the pair of tabs, are detachably received, and further comprises an aperture formed in the second half through which a top surface of the projection is exposed for manual manipulation and displacement of the projection away from the second half when disconnection of the first and second halves is required.
A blade carrier is disposed in the enclosed space and arranged to be slidable along elongate guide surfaces which project from at least one of the first and second halves. This blade carrier is adapted to receive two different blades and is disposable on the elongate guide surfaces in two distinct orientations. The blade carrier is adapted to support a cutting blade in a
McDermott & Will & Emery
Rachuba M.
Safety Razor Company
Tran Kim Ngoc
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