AU2004100061A4 - Pruning tool - Google Patents

Description

PRUNING TOOL Field of the Invention The present invention relates generally to garden tools and, in particular, to tools for cutting tree branches.

Background Gardening often involves cutting tree branches, and typically a gardener uses a saw for this purpose. The sap which is typically present in tree branches, however, tends to make a saw blade jam, and other branches can often obstruct the stroke of the saw, making it awkward to complete cutting of the branch. Furthermore, as the branch is cut, the branch can tilt, jamming the saw blade in the cut.

Summary of the Invention It is an object of the present invention to substantially overcome, or at least ameliorate, one or more disadvantages of existing arrangements.

According to a first aspect of the present invention, there is provided a tool for cutting a tree branch, the tool comprising at least one cutting device; engagement means for bringing the at least one cutting device into cutting disposition against the branch; a handle for at least partially rotating the at least one cutting device about the branch to thereby cut into the branch; and pressure means for maintaining the at least one cutting device in said cutting disposition.

Other aspects of the invention are also disclosed.

Brief Description of the Drawings One or more embodiments of the present invention will now be described with reference to the drawings, in which: Figs. 1A to 1C show one embodiment of the pruning tool in which upper and lower blades are brought successively closer to each other as the branch is severed; 030204

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Figs. 2A and 2B show a hinged arrangement of an engagement frame in Figs. 1A to 1C; Figs. 3A and 3B show one example of how the blades, the engagement frame, and the handle are arranged in the pruning tool of Figs. 1A-1C; Fig. 4 shows the view in Fig. 3B in enlarged form, and depicts one arrangement for securing the upper blade to the engagement frame; Figs. 5A and 5B show two arrangements of cutting teeth, one used for singledirection-cutting and one used for reciprocating-direction-cutting; and Fig. 6 depicts how the cutting teeth of the upper and lower blades can be biased in a grazing fashion.

Detailed Description including Best Mode It is to be noted that the discussion contained in the "Background" section relating to prior art arrangements refers to devices which form public knowledge through their use. Such should not be interpreted as a representation by the present inventor or patent applicant that such devices in any way form part of the common general knowledge in the art.

Where reference is made in any one or more of the accompanying drawings to steps and/or features, which have the same reference numerals, those steps and/or features have for the purposes of this description the same function(s) or operation(s), unless the contrary intention appears.

Figs. 1A to 1C show one embodiment of the pruning tool in which upper and lower blades (these being particular examples of "cutting devices") are brought successively closer to each other as a branch (not shown) is severed using the tool. Fig.

1A shows a frame 100 in which an upper blade 102 and a lower blade 106 are mounted.

Left hand edges 103 and 105 of the upper and lower blades 102 and 106 respectively are shown using dashed lines, indicating that these edges are recessed into slots in the frame 030204

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-3- 100. The upper and lower blades have cutting teeth 101 and 104 respectively. In the present arrangement, the upper blade 102 is mounted in a fixed fashion relative to the frame 100, and does not move with regard to the frame 100 as the branch is cut. The lower blade 106 moves relative to the frame 100, as illustrated by reference numerals 110 and 112 in Figs. 1B and 1C respectively, as the branch is cut. The lower edge 111 of the upper blade 102 is shown using dashed lines in Fig. 1C.

A handle 100 has a threaded drive shaft 109, which is threaded through a threaded aperture 108 in the frame 100. The handle 100 can be tightened by rotating it in a direction 113, thereby rotating the threaded drive shaft 109. The threaded drive shaft 109 has a connector 107 attached thereto, and the connector 107 is attached to the lower blade 106. The connector 107 is attached to the drive shaft 109 using a rotatable joint 322 (see Fig. 3B). The connector 107 is attached to the lower blade 106 using a press fit joint 413 (see Fig. Rotation of the handle 100 in the direction 113 thus urges the lower blade 106 in an upwards direction 116 towards the upper blade 102. Rotation of the handle 100 in a direction opposite to 113 draws the lower blade 106 away from the upper blade back towards the lower part of the frame 100.

From a functional perspective, the branch (not shown) is inserted into the space between the upper and lower blades 102, 106. The handle 100 is then tightened in the direction 113 to bring the cutting teeth 101, 104 of upper and lower blades 102, 106 respectively into firm engagement with the branch. The tool is then rotated in a direction 114 in order to commence cutting the branch. The handle 100 is periodically tightened in the direction 113 to maintain the pressure of the cutting teeth 101, 104 against the branch.

As the tool is rotated in the direction 114, and as the upper and lower blades converge urged by tightening of the handle 100 as shown in the respective Figs. 1A to 1C, the branch is progressively cut through until it is severed. For the (two-bladed) arrangement 030204

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-4in Figs. 1A-1C the maximum diameter of the branch to be severed is depicted by an arrow 115.

The mechanical advantage provided by the lever action of the handle 100 being rotated in the direction 114 enables the branch to be cut using significantly less effort than would be required using a saw. Although Figs. 1A to 1C show only the single handle 100, a second handle (not shown) can be attached to the upper part of the frame 100 to enable two handed operation of the tool.

Furthermore, although the arrangement of Figs. 1A to 1C uses the handle 100 and the threaded shaft 109 to periodically re-establish and thus maintain the pressure of the cutting teeth 101, 104 against the branch, a spring loaded arrangement can also be used to maintain the aforementioned pressure as the branch is cut, thereby relieving the user of the tool of the task of periodically tightening the handle 100.

Although the arrangement in Figs. 1A to 1C show two blades 102 and 106 which work cooperatively to cut the branch, a single blade could be used in an alternate arrangement. Thus, for example, the lower blade 106 could be formed without the cutting teeth 104, thereby acting as a clamping means but not a cutting means. In such an arrangement, the upper blade 102 alone would perform the cutting of the branch.

Alternately, the upper blade 102 could be smooth and the lower blade 106 could do the cutting. In such (one-bladed) arrangements, the maximum diameter of the branch if it is to be severed would be approximately 50% of the diameter depicted by the arrow 115.

Although Figs. 1A-1C show the blades 102 and 106 having curved toothed edges, this having the advantageous property that the blades 102,106 also serve to hold the branch roughly in the centre of the blades 102, 106 as the branch is cut, straight toothed edges could also be used.

Figs. 2A and 2B show a hinged arrangement for the engagement frame 100 of Figs. 1A to 1C. Fig. 2A shows the frame in an open condition, wherein an upper frame

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030204 section 200 is hinged away from a lower frame section 203 using a hinge 202. A branch is inserted into the space between the upper and lower blades as depicted by an arrow 201.

Fig. 2B shows the frame in a closed condition, in which the upper and lower frame sections 204, 206 are hinged together using the hinge 202, and are secured in place by a removable locking pin 205. Other arrangements can be used for allowing the branch to be inserted. Thus for example, the upper frame section 200 could be secured to the lower frame section 203 using removable pins on both sides, thereby avoiding the need for the hinge 202.

Figs. 3A and 3B show one example of how the blades, the engagement frame, and the handle are arranged. Fig. 3A shows a front view of one embodiment of the pruning tool, and Fig. 3B shows a sectional view from the direction of arrows 300, 321.

The tool in Fig. 3A has a frame 301 which has a top edge 311 when shown "in section" (ie in a sectional view) in Fig. 3B. An upper blade 302 in Fig. 3A is shown in section as 313 in Fig. 3B, and the upper blade 313 is recessed into a slot 312 in a face 304 of the frame 301. The slot 312 extends into the upper part 311 of the frame 301 in Fig. 3B.

Teeth such as 303 in the upper blade 302 of Fig. 3Aare shown as 314 in Fig. 3B. A lower blade 306 in Fig. 3A is shown as 317 in section in Fig. 3B, and the blade 317 is recessed into a slot 315 in the face 304. It is apparent that the slot 312 is just long enough to hold the upper blade 313, but not long enough to allow the blade 313 to move significantly with reference to the frame 301. In contrast, the slot 315 is long enough to allow the lower blade 317 to move along the slot 315, thus converging towards the upper blade 313 when urged upwards by a threaded shaft 320 and a connector 318 when a handle 324 is tightened. In an alternate arrangement, the lower blade 306 can be fixed, while the upper blade 302 is moved towards the lower blade in order to sever the branch.

Since the blades 302 and 306 are shown, in Fig. 3B, to be parallel to, and offset from, each other, their respective cutting teeth converge as the shaft 320 is tightened, but 030204

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the teeth do not come into contact with each other (see however the effect of biasing the teeth of the blades as described in relation to Fig. In another arrangement however, straight and not curved toothed blade edges are used. In such an arrangement, the top and bottom blades 302, 306 can be positioned in the same slot 315. In this case, the slot 315 extends into the upper part 311 lof the frame 301 in the same manner as the slot 312. The slot 312 is not needed in this arrangement, and is not present. In this arrangement, the blades 302, 306 lie in the same plane, and their straight toothed edges come into contact when the blades converge.

Fig. 4 shows the depiction of Fig. 3B in enlarged form, and also shows one arrangement for securing the upper blade to the engagement frame. An upper blade 404 is located in a slot 403 which extends into an upper edge 401 of the frame. The upper end 410 of the slot 403 is shown in expanded form in an inset 410'. In the inset 410' the upper blade (referred to as 404') is located in the slot (referred to as 403') and the blade 404' has a bulge 412 at the upper edge of the blade 404'. The slot 403' has a groove 411 into which the protrusion 412 fits, thereby holding the blade 404' in place once the blade 404' is "clicked" into position. The blade 404' can be relatively easily clicked into and out of position, thereby allowing for convenient replacement of the blade 404' when it becomes blunt.

A lower blade 406 is located in a slot 402 along which the blade 406 slides in use. A connector 407 is coupled to the lower blade 406 with a press fit at 413. The press fit can be loose enough to allow engagement and dis-engagement of the blade 406 from the connector 407 by hand, thereby allowing for convenient replacement of the blade 406 when it becomes blunt.

The connector 407 is coupled to a threaded drive shaft 409 by a rotatable joint 412. The threaded drive shaft 409 is threaded through a threaded aperture 408 in the lower part 414 of the frame.

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Figs. 5A and 5B show two arrangements of cutting teeth, one used for single direction cutting and one used for reciprocating direction cutting. Fig. 5A shows an upper blade 500 with clockwise oriented teeth 501. A lower blade 505 with clockwise oriented teeth 504 is also shown. The upper blade 500 and the lower blade 505 are, in this arrangement, intended to be rotated in a continuous (single-direction) clockwise manner as depicted by arrows 508 and 509 in order to cut a branch (not shown) upon which the upper and lower blades 500, 505 are brought to bear. Fig. 5B shows an alternate arrangement with an upper blade 502 with clockwise oriented teeth 503, and a lower blade 506 with anti-clockwise oriented teeth 507. When the blades are rotated in a clockwise manner as depicted by an arrow 510, the teeth 503 cut a branch upon which the teeth 503 are brought to bear, because the cutting edges of the teeth 503 are driven into the branch by the clockwise movement of the blades. The teeth 507 will not produce effective cutting of the branch in this case, because the cutting edges of the teeth 507 are not driven into the branch by the clockwise movement of the blades.

When the blades are rotated in a counter-clockwise manner as depicted by an arrow 511, the teeth 507 cut the branch upon which the teeth 507 are brought to bear, because the cutting edges of the teeth 507 are driven into the branch by the counterclockwise movement of the blades. The teeth 503 will not produce effective cutting of the branch, because the cutting edges of the teeth 503 are not driven into the branch by the counter-clockwise movement of the blades.

The upper blade 502 and the lower blade 506 are, in this arrangement, intended to be rotated in a reciprocal manner as depicted by arrows 510 and 511 in order to cut a branch (not shown) upon which the upper and lower blades 500, 505 are brought to bear.

Fig. 6 depicts hows the cutting teeth of the upper and lower blades are biased in a "grazing" fashion, to ensure that the respective slots or kerfs produced by the upper and lower blades in the branch "graze" each other, ensuring proper severing of the branch 030204

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when the upper and lower blades are positioned in the parallel/offset arrangement as shown in Figs. 3A-3B, for example. In this context, the term "graze" means that the grazing teeth just miss touching each other as they converge and pass each other as their respective blades converge and pass each other (see Figs. 1A-1C).

An upper blade 404 has a tooth 600 biased towards the right, and a tooth 601 with a left hand bias. The tooth 601 grazes a dashed line 606 which represents the plane which is grazed by a right most tip of a tooth 603. The lower blade 406 has a tooth 604 biased towards the left, and the tooth 603 with a right hand bias. The tooth 603 grazes the dashed line 602 which represents the plane which is grazed by the left most tip of the tooth 601. The depicted grazing contact between the teeth 601 and 603 ensures that the respective kerfs produced by the upper and lower blades graze each other when the blades converge, ensuring proper severing of the branch.

Industrial Applicability It is apparent from the above that the arrangements described are applicable to the gardening and landscaping industries.

The foregoing describes only some embodiments of the present invention, and modifications and/or changes can be made thereto without departing from the scope and spirit of the invention, the embodiments being illustrative and not restrictive.

Thus, for example, although Figs. 1-6 depict cutting devices in the form of blade(s) 102, 106 (see Fig. 1) which are brought into convergence by a threaded drive shaft 109 which pushes the blade(s) together, a chain type cutting device (or two such devices with cutting "teeth" having opposed orientations) similar to that used in chain saws can be used instead. In such an arrangement the cutting chain(s) are attached to a handle at one end of the chain, and the other end of the chain(s) are first wrapped once around the branch to be cut, after which said other end(s) of the chain(s) are attached to a drive shaft coupled to the handle. The cutting chain(s) are then rotated around the branch 030204

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using the handle, and the drive shaft is periodically tightened, thereby reducing the internal radius of the looped cutting chain(s) to thereby cut through the branch. In yet another arrangement, an abrasive wire can be used as a cutting device instead of the above-noted cutting chain(s).

AUSTRALIA ONLY In the context of this specification, the word "comprising" means "including principally but not necessarily solely" or "having" or "including", and not "consisting only of'. Variations of the word "comprising", such as "comprise" and "comprises" have correspondingly varied meanings.

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Claims (4)

1. A tool for cutting a tree branch, the tool comprising: at least one cutting device; engagement means for bringing the at least one cutting device into cutting disposition against the branch; a handle for at least partially rotating the at least one cutting device about the branch to thereby cut into the branch; and pressure means for maintaining the at least one cutting device in said cutting disposition.

2. A tool according to claim 1, wherein the at least one cutting device comprises one of: a blade; an opposed pair of blades; a chain-type cutting device; and an abrasive wire type cutting device.

3. A tool according to claim 1, wherein the tool is either rotated in a continuous circular direction to thereby sever the branch or moved in a repetitive reciprocal movement to thereby sever the branch.

4. A tool according to claim 1, wherein the pressure means is one of a threaded drive shaft coupled to the handle, the threaded drive shaft being adapted to urge the at least one cutting device against the branch when the handle is tightened, and a spring loaded mechanism adapted to urge the blade against the branch. 030204 TOOLH.DOC -11- A tool for cutting a tree branch, substantially as described herein with reference to the accompanying drawings. DATED this 3 rd Day of February 2004 MARTIN FRIEDGUT 030204 TOOLH.DOC