The present invention relates to a handheld knife having an exchangeable blade. In particular, the present invention relates to an exchangeable blade knife having an improved system for coupling the blade to the handle.
Fixed blade knives have a sharpened blade that is attached to a handle in any one of a variety of ways known in the art. In order to provide a secure feel and strong design, the blade typically has a tang portion that extends well into the handle, in many designs extending the length of the handle through to the back of the knife. The handle sides are secured to the tang of the blade with screws or other fasteners or with an adhesive. Because the blade and tang are typically made of metal, such as with steel, a one-piece blade and tang extending the length of the overall knife provides a strong design, as compared to designs having a shorter tang that is secured near the front end of the handle.
Certain knife designs provide the feature of a removable blade. A removable blade may be desirable in order to provide a knife system having a single handle that may be used with various types of blades, such as knife blades, saw blades, and other tools having a common attachment mechanism that may be secured to the handle. In such an exchangeable blade design, a mechanism used to secure the interchangeable blades with the handle is provided, such as a screw, lever, or button-type mechanism.
One challenge associated with exchangeable blade knife designs relates to securely coupling the blade to the handle. Because such designs are intended to provide the functionality of a fixed blade knife while providing the additional feature of an exchangeable blade, it is desirable to provide the secure feel of a conventional fixed blade knife having a tang that extends the length of the handle while also providing the exchangeability function. Accordingly, the design of the exchangeable blade knife must minimize movement or play in the blade when the blade is attached to the handle. Such play is typically manifested in uninhibited lateral movement of the blade that is permitted by free space between the blade tang and the handle sides when the components are assembled. Such free space is typically the result of manufacturing tolerances resulting in variability in the thickness of the blade tang and the thickness of the receiving slot in the handle.
One way of reducing play in the blade is to use a screw or screws to attach the exchangeable blade to the handle. Tightening the screw or screws reduces blade movement within the handle. However, a disadvantage of this approach is that the utilization of screws hampers the ease of exchanging the blade by requiring the user to manually remove and re-attach the screw or screws, and may require the use of an additional tool such as a screwdriver. Further, the use of a screw presents the disadvantage of having a loose part, such as the screw or a portion of the handle side, when exchanging the blade, which can increase the chances of dropping and perhaps losing a necessary part of the knife when exchanging blades.
Another approach to reducing movement of the blade in the handle is to tighten the manufacturing tolerances of the blade and/or the handle. For example, tightening the tolerance of the components will result in a decrease in the amount of play between the blade and the handle when the knife is assembled. A disadvantage of this approach is that tightening tolerances results in an increase in manufacturing costs, both in tooling and in the number of parts that must be reworked or discarded because the manufactured parts do not meet the prescribed tolerances.
Accordingly, there is a need for an exchangeable blade knife that is designed to reduce the amount of play between the blade and the handle when the knife is assembled while still affording an easy method of removing and attaching the exchangeable blades and without requiring attachment parts that must be removed from the handle when exchanging the blade. Further, there is a need for an exchangeable blade knife that exhibits reduced movement or play in the blade without also requiring higher manufacturing tolerances in the blade or handle components.
It would be desirable to provide a system and/or method that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments that fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.
The invention relates to a knife having a handle and a blade adapted to be removably coupled to the handle. A bias mechanism is coupled to the handle, the bias mechanism applying a bias on the blade in a lateral direction to press the blade against the handle. The blade may be removed from the handle without also removing the bias mechanism from the handle.
The invention further relates to an exchangeable blade knife system having a handle and a blade. The blade has a working position in which the blade is secured to the handle and a removed position in which the blade is not secured to the handle. A bias mechanism is coupled to the handle, the bias mechanism applying a bias on the blade in a lateral direction to press the blade against the handle when the blade is in the working position. The bias mechanism remains coupled to the handle when the blade is moved from the working position to the removed position.
The invention further relates to a knife having a handle and a blade adapted to be removably coupled to the handle. A means for biasing the blade against the handle applies a bias on the blade in a lateral direction to press the blade against the handle. The blade may be removed from the handle without removing the means for biasing the blade against the handle from the handle.
The invention is capable of other embodiments and of being practiced or being carried out in various ways. Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims.
The invention will become more fully understood from the following detailed description, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like elements, in which:
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In another exemplary embodiment (not shown), the end portion 78 and the aperture 44 may be configured to mechanically interfere with one another to function as a blade bias mechanism in addition to a release and locking mechanism. For example, the end portion 78 may be tapered such that the distal end of the end portion is wider than the diameter of the aperture so that the end portion 78 wedges into the aperture 44 when the blade 14 and handle 12 are assembled. Because of the interlocking of the end portion 78 and the aperture 44, the release button spring 42 provides a bias on the tang 22 in a lateral direction against the handle 12 when the blade 14 and handle 12 are assembled in such an embodiment.
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In operation, the blade 14 may be released from the handle 12 in order to exchange the blade 14 with another blade or tool by depressing the release button 40 and pulling the blade 14 out of handle 12. Accordingly, the required mechanical actions necessary to disassemble blade 14 and handle 12 are simplified relative to devices that require the removal of fasteners or the activation of multiple components such as levers and so forth to release the exchangeable blade. Further, the removal operation does not result in loose parts, such as screws, that present the risk of being lost when a blade is being removed and replaced.
In order to address the issue of excessive movement or play in the blade 14 when assembled with the handle 12, especially without the utilization of extra fasteners, the blade bias mechanism removes play by applying force in a lateral direction on the tang 22. The blade bias mechanism may be in the form of the ball and spring mechanism 64 or the pin 50 and spring 52 in two of the embodiments described herein, but may also take other mechanical forms involving mechanisms that apply force on the blade 14 in a lateral direction in order to remove play on the blade 14 when the knife 10 is assembled. Without the utilization of the blade bias mechanism (one such mechanism or multiple mechanisms in combination with one another) the tolerances on the thickness of the blade and handle components would have to be tightened to reduce the amount of play, with a corresponding increase in manufacturing costs and defects. The addition of the blade bias mechanism allows for an increased tolerance, such as permitting a 0.020 inch mismatch in blade-to-handle thickness, both decreasing the cost to manufacture and increasing the quality of the knife relative to alternative approaches of tightening the tolerances on the thickness of all components to within ±0.001-0.002 inches.
While the detailed drawings and specific examples given herein describe various-exemplary embodiments, they serve the purpose of illustration only. It is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the preceding description or illustrated in the drawings. For example, the particular release mechanism and tang configuration is but one way of attaching an exchangeable blade to a handle. Further, the blade bias mechanism is shown in one embodiment as having a shaft and flange configuration to apply a spring bias to the tang but may take other forms that permit the application of a bias to the blade to reduce play in the blade Furthermore, other substitutions, modifications, changes, and omissions may be made in the design, operating conditions, and arrangements of the exemplary embodiments without departing from the scope of the invention as expressed in the appended claims.