Patent Application
20080295341
The present invention relates to a hand-operated cutting tool. The present invention relates more particularly to a hand-operated cutting tool, such as a pruner, or a pair of snips or shears, having a rear pivot joint for actuating the cutting jaws of the tool.
It is generally known to provide a hand-operated tool such as a snips, shears, scissors or the like having a pair of pivoting members with sharpened edges that slide past one another to cut an object placed between the sharpened edges. However, such known tools typically have handles arranged to pivot at a forward or intermediate location for actuating the cutting jaws of the tool, with the rear (open) ends of the handles unattached to one another so that a user may grip and squeeze the rear ends together to actuate the cutting jaws. Such known tools tend to have the disadvantage that the stronger fingers of a user's hand (typically the first two fingers) are arranged to grip the handle near the pivot point and away from open ends (where maximum leverage in such tools is often generated).
Accordingly, it would be desirable to provide a hand-operated cutting tool, such as a pruner or pair of snips, having a pair of pivotally connected handles with a rear pivot point and an “open” end near the front of the tool. It would also be desirable to provide a hand-operated cutting tool having a pair of pivotally interconnected cutting jaws that are also connected near the open front of the handles. It would also be desirable to provide a hand-operated cutting tool where the handles and the cutting jaws are connected for operation as a four-bar linkage. It would also be desirable to provide a hand-operated cutting tool that is spring-biased toward an open position for ease of use in multiple cutting operations. It would also be desirable to provide a hand-operated cutting tool that includes a lock device for maintaining the blades in a closed position. It would further be desirable to provide a hand operated cutting tool having handles shaped or contoured to provide an ergonomic design.
Accordingly, it would be desirable to provide a hand-operated cutting tool having any one or more of these or other desirable features.
According to one embodiment, a hand-operated cutting tool includes a first handle and a second handle each having a first end and a second end. A first pivot connection couples the first ends of the handles for movement of the handles relative to one another between an open position and a closed position. The tool also includes a first elongated member and a second elongated member each having a pivot end and a jaw end and an intermediate region therebetween, with the pivot end of the first elongated member pivotally coupled near the second end of the first handle and the pivot end of the second elongated member pivotally coupled near the second end of the second handle. A second pivot connection couples the intermediate regions of the elongated members for movement of the elongated members relative to one another.
According to another embodiment, a hand-operated cutting tool includes a first handle and a second handle each having a first end and a second end, with the first ends pivotally coupled together to form a first pivot point. The tool also includes a first elongated member and a second elongated member each having a first end and a second end and an intermediate region therebetween, with the second ends comprising a cutting jaw. A second pivot point couples the intermediate regions of the elongated members to one another. A third pivot point couples the first end of the first elongated member to the first handle and a fourth pivot point couples the first end of the second elongated member to the second handle, so that the handles and the elongated members and the pivot points cooperate as a four-bar linkage for movement of the cutting jaws between an open position and a closed position.
According to a further embodiment, a hand-operated cutting tool includes a first handle and a second handle each having a first end and a second end with a first connection pivotally coupling the first ends of the handles for movement of the handles between an open position and a closed position. The tool also includes a first elongated member and a second elongated member each having a handle end and a cutting end and an intermediate region therebetween, with the handle end of the first elongated member coupled to the first handle and the handle end of the second elongated member coupled to the second handle A second connection pivotally couples the intermediate regions of the elongated members for movement of the cutting ends between an open position and a closed position as the handles are moved between the open position and the closed position.
Referring to the FIGURES, a hand-operated cutting tool, shown for example as a pruner, or pair of snips or shears is shown according to an exemplary embodiment. The tool is shown to include a pair of handles and a pair of elongated members that are connected together in a four-bar linkage arrangement according to the illustrated embodiment. The handles are pivotally connected to each other at a rear end of the tool, and are each pivotally connected to a rear end of one of the elongated members near a front end of the tool. The elongated members are pivotally connected at an intermediate location so that the front ends of the elongated members (shown to include cutting jaws) are opened and closed in a cutting operation as the front ends of the handles are opened and closed (i.e. moved away and toward one another respectively). The handles are shown to include ergonomically contoured surfaces, to minimize user-fatigue during extended use of the tool. The tool is also shown to include a spring that biases the front ends of the handles toward the open position (i.e. to open the cutting jaw) to automatically open (or assist in opening) the jaws following completion of a cutting operation. A lock device is also provided to lock the handles in a closed position when the tool is not in use. The locking device is actuatable between a “locked” position to maintain the cutting jaws in the closed position and a “use” position to permit the cutting jaws to be opened (e.g. spring-biased or “sprung-open”).
Accordingly, the tool can be used to cut a wide variety of objects between the cutting jaws, by gripping and squeezing the handles with the (typically) stronger first several fingers of a user's hand located near the open (i.e. front) end of the handles. It should be noted that the connection between the handles and the elongated members may be a pivot connection (as shown in the Figures), but may also include other types of connections to permit enhanced leverage to be applied to the cutting jaws. For example, a sliding connection may be provided for a lever device, or a surface having projections may be provided for a gear device, etc. In addition, the lock device may operate in any suitable manner (e.g. slide, push-pull, lever, etc.). Further, the cutting jaw portion of one of the elongated members may be provided in the form of blades to permit operation of the tool in the manner of a shears, snips, scissors, etc., but may also include a generally planar surface arranged to bear against the sharpened internal edge of the other blade portion (e.g. in an anvil-like manner), or may be provided with a hook arranged to slide past an opposing blade during the cutting operation (e.g. in the manner of a “bypass” type pruner, etc.). Accordingly, the embodiments illustrated in the FIGURES are shown by way of example, and any of a wide variety of blades, handles, and connection styles or shapes, and combinations thereof, will be readily apparent to a person of ordinary skill in the art after reviewing this disclosure. All such variations are intended to be within the scope of the invention.
Referring to
The handles 20, 40 are shown having an ergonomic shape adapted to fit a palm of user's hand in a comfortable grip, and include a longitudinal convex profile 22, 42 with a forward lip 24, 44, and a transverse convex profile 26, 46. The handles 20, 40 include a first end (shown as a “front” end 28, 48) and a second end (shown as a “rear” end 30, 50). The rear ends 30, 50 of the handles 20, 40 are coupled together by a pivot-type connection 12 (e.g. with a pin, sleeve, bushing, etc.) for pivotal movement of the front ends 28, 48 of the handles 20, 40 between an open position (as shown in
Handles 20, 40 are also shown to include an internal rib 32, 52 having an aperture 34, 54 arranged so that the apertures 34, 54 are axially aligned when the front of the handles are in the closed position. A lock device 100 (shown for example as a slide-type lock device) is provided with opposed engagement surfaces 102, 104. A link 106 interconnects the engagement surfaces 102, 104 and extends through an aperture 108 in the rib of one of the handles. One of the engagement surfaces also includes a projection (shown as a pin or peg 110) that is configured to engage both apertures 34, 54 when the front of the handles are moved to the closed position (to align the apertures) and a force is applied to one of the engagement surfaces to shift peg 110 in a transverse direction to enter the apertures and actuate the lock device. In order to disengage the lock device, a force is applied to the opposite engagement surface to shift the peg 110 in an opposite transverse direction to withdraw the peg from one or both apertures 34, 54. Handles 20, 40 are further shown to include receptacles 36, 56 and pins 38, 58 near the front ends 28, 48 to receive and establish a pivot connection 14, 16 with an end of the elongated members 60, 80.
Referring further to
The relative dimensions of the handle portions and the elongated member portions that constitute the four-bar linkage may be arranged to provide any desired amount of mechanical advantage, corresponding to the type of objects intended (or desired) to be cut by the cutting jaws. For example, the handle portions may have a length that is greater than the length of the portions of the elongated members (as shown by way of example in the FIGURES). Alternatively, the handle portions may have a length that is less than the length of the portions of the elongated members, or the handle portions and the elongated member portions may have lengths that are substantially equal. According to a further alternative embodiment, one or both of the handle front pivot connections may be replaced with other types of connections that may be desirable for providing a tool with a greater mechanical advantage at the cutting jaws. For example, an additional link with a sliding connection may be provided, or a pair of gear segments may be provided to transfer and amplify a closing force from the handles to the cutting jaws.
The cutting jaws 66, 86 of the present embodiment are shown by way of example in
According to any exemplary embodiment, the hand-operated cutting tool provides a tool having a pair of handles that are pivotally connected to one another at a rear end of the handles for opposing movement of the front ends of the handles (e.g. expansion-contraction, etc.) between an open position and a closed position. Elongated members with mid-portions pivotally connected to one another each have one end pivotally connected to the front end of a corresponding handles to create a four bar linkage. An opposite end of the elongated members project forwardly to form a pair of cutting jaws that are opened and closed as the handles are opened and closed to perform a cutting operation. Placement of the pivot connection for the handles at a rear end of the handles is intended to permit the stronger portion of a user's hand to generally coincide with the portion of the handles having the greatest range of motion, to provide an increased force at the cutting jaws.
According to other alternative embodiments, the tool may be provided with, or without, a lock device (for maintaining the handles in a closed position) and/or a spring-assist (for biasing the cutting jaws and handles to an open position). The elongated members may be formed from any material suitable for the application, such as steel. The handles may be made from a material such as (among others) glass-filled nylon, die-cast zinc, or plastic, in a molding or other suitable process.
It is also important to note that the construction and arrangement of the elements of the hand-operated cutting tool as shown schematically in the embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible without materially departing from the novel teachings and advantages of the subject matter recited.
Accordingly, all such modifications are intended to be included within the scope of the present invention. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present invention.
The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating configuration and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present invention as expressed in the appended claims.
