UTILITY KNIFE

A utility knife includes a first handle portion and a second handle portion removably coupled to the first handle portion to define a housing. The first handle portion includes a first bore and the second handle portion includes a second bore. The utility knife also includes a blade carrier slidably received within housing and a blade removable coupled to the blade carrier for movement with the blade carrier relative to the housing. The utility knife also includes a double-lead fastener including a head, an unthreaded portion received within the first bore, and a double-lead threaded portion received within the second bore to couple the first handle portion and the second handle portion.

DETAILED DESCRIPTION

FIGS. 1-5illustrate a knife10which is a utility knife10in the illustrated embodiment. The knife10includes a housing14, a blade18, and a blade carrier22that positions the blade18in a desired position relative to the housing14.

With reference toFIG. 1, the housing14includes a first handle portion26and a second handle portion30that cooperate to define the housing14. The first handle portion26and the second handle portion30are removably coupled together by a fastener34, which will be described in further detail below. The housing14includes a front end38, a back end42, sidewalls46,50that extend from the front end38to the back end42, and a top wall54and a bottom wall58that both extend from the front end38to the back end42. The housing14is generally hollow and includes an aperture62in the front end38through which the blade18can extend. The housing14also includes a groove66or notch formed in the bottom wall58, near the front end38of the housing14. The groove66exposes a small portion of the blade18and allows a user of the knife10to perform certain cutting operations (e.g., stripping wire, cutting string) even when the blade18does not extend through the aperture62(FIG. 2).

With reference toFIGS. 2 and 3, the interior of the housing14defines a track70that extends to the aperture62at the front end38of the housing14. The blade carrier22is guided by the track70to slide with respect to the housing14in the direction of the arrows74and78. The blade carrier22includes a projection82and an elongate slot86extending through the blade carrier22(FIG. 3). The projection82extends from the blade carrier22and through a notch90in the blade18to couple the blade18with the carrier22for movement with the carrier22along the track70(FIG. 2). An actuator94extends through a slot98formed in the top wall54of the housing14to provide the user with a place to grip the blade carrier22(e.g., with the user's thumb) to slide the blade carrier22with respect to the housing14. In the illustrated embodiment, the actuator94is rigidly coupled to the blade carrier22. In other embodiments, the actuator94can be operably coupled to the blade carrier22via a linkage or other suitable arrangement. The blade carrier22is continuously biased towards the rear of the housing14by a coil spring102, such that the blade18is automatically retracted into the housing14if the actuator94is released from the forward position (FIG. 3).

With reference toFIG. 3, the second handle portion30includes a pin-like projection106that is received in the elongate slot86of the blade carrier22. The projection106engages with a rear end110of the slot86when the blade carrier22is in the extended position to limit movement of the blade carrier22to the extended position. The projection106engages with a front end114of the slot86when the blade carrier22is in the retracted position to limit movement of the blade carrier22to the refracted position. Accordingly, the elongate slot86of the blade carrier22slides along the projection106as the blade carrier22moves between the extended position and the retracted position. In the illustrated embodiment, a projection106receives a threaded fastener118to retain the blade carrier22with the second handle portion30(e.g., when the first and second handle portions26,30are disassembled). A head120of the threaded fastener118engages with a beveled periphery122of the elongated slot86to retain the blade carrier22while still permitting movement of the blade carrier22between the extended position and the retracted position.

Referring toFIG. 4, the first handle portion26includes a first bore126and the second handle portion30includes a second bore130. The first bore126and the second bore130are aligned when the first and second handle portions26,30are assembled to receive the fastener34that holds the first and second handle portions26,30together. Access to the blade18(e.g., for replacing the blade18) is permitted by removing the fastener34and separating the two handle portions26,30of the housing14.

Illustrated inFIG. 5, the fastener34defines a pitch distance134(referred to hereafter as “pitch”) and a lead distance138(referred to hereafter as “lead”). The pitch134is the axial distance between adjacent crests of the fastener34. The lead138is the axial distance that the fastener34is advanced for each complete rotation of the fastener34. A conventional threaded fastener (not shown) includes a single thread wrapped helically around the fastener34. The pitch and the lead of the conventional fastener are equal; therefore the conventional fastener advances an axial distance equal to the pitch for each complete rotation. In the illustrated embodiment, the fastener34is configured as a double-lead screw (also referred to as a double-start screw or a double-threaded screw). The illustrated fastener34includes two separate threads140a,140boffset 180 degrees and wrapped helically around the fastener34. As such, the fastener34advances twice the pitch134per rotation (i.e., the lead138is twice the pitch134), thereby requiring less rotation to couple or decouple the first and second handle portions26,30than if a conventional fastener were used.

The illustrated fastener34includes a head142, a threaded portion146, and an unthreaded portion150between the head142and the threaded portion146. The head142includes a gripping portion154to enable the user to rotate the fastener34without using a screwdriver or other tools. In the illustrated embodiment, the gripping portion154is formed around the head142. In other embodiments, the gripping portion154can be integrally formed with the head142or machined from the head142. The threaded portion146has a larger effective diameter158than a diameter162of the unthreaded portion150. The threaded portion146is received in a threaded portion166of the second bore130when the first and second handle portions26,30are coupled together (FIG. 4).

The first bore126includes an unthreaded portion170and a threaded portion174. The threaded174portion has a slightly smaller diameter than the unthreaded portion170. When the user loosens the fastener34to open or separate the handle portions26,30(i.e., to change the blade18), the threaded portion146of the fastener34is disengaged from the threaded portion166of the second bore130. However, the fastener34remains attached to the first handle portion26because the head142of the fastener34and the threaded portion146of the fastener34are unable to pass freely through the threaded portion174of the first bore126when the handles portions26,30are separated. Therefore, the fastener34does not easily fall out of the first bore126and become lost. If desired, the user could remove the fastener34from the first handle portion26by aligning the threads146of the fastener34with the threads174of the first bore126and by rotating the fastener34while pulling somewhat on the fastener34. However, the above-described arrangement prevents the fastener34from unintentionally falling out of the bore126of the first handle portion26when the handle portions26,30are separated (FIG. 2).

With reference toFIG. 2, the interior of the housing14defines a spare blade compartment178for storing at least one replacement blade (not shown). The spare blade compartment178is accessed by unscrewing the fastener34and removing one of the handle portions26,30, as described above. The replacement blade(s) are held snugly within the spare blade compartment178by a cantilevered leaf spring182supported by the first handle portion26. The cantilevered leaf spring182exerts a biasing force against the replacement blades(s) within the spare blade compartment178when the first and second handle portion26,30are assembled.

In operation, the user manipulates the actuator94to slide the blade carrier22from the retracted position to the extended position, against the biasing force of the spring102. This exposes the blade18through the aperture62and enables the user to perform a cutting operation. When the user releases the actuator94, the spring102causes the blade carrier22to move to the retracted position in the direction of arrow78, withdrawing the blade18inside the housing14. A small portion of the blade18remains exposed through the notch66in the housing14, allowing the user to perform certain cutting operations, such as wire stripping.

To replace the blade18, the user grips the gripping portion154of the fastener34and rotates the fastener34in a first direction (i.e., counterclockwise). Because the fastener34is configured as a double-lead screw, a relatively small degree of rotation is required to disengage the threaded portion146of the fastener34from the threaded portion166second bore130. Once the fastener34is disengaged from the second handle portion30, the user can remove the first handle portion26to gain access to the blade18and the spare blade compartment178in order to replace the blade18. The fastener34is retained within the first bore126of the first handle portion26by the head142and the threaded portion146of the fastener34. This prevents the user from misplacing the fastener34. If desired, the user can remove the fastener34from the first handle portion26by aligning the threads146of the fastener34with the threads174of the first bore126and by rotating the fastener34while pulling somewhat on the fastener34. To reassemble the utility knife10, the user aligns the first bore126of the first handle portion26with the second bore130of the second handle portion30, then rotates the fastener34in a second direction (i.e., clockwise). As mentioned above, because the fastener34is configured as a double-lead screw, only a relatively small degree of rotation is required to secure the first and second handle portions26,30together.