NZ211651A - Rotary mower blade; cutting ring rotatably mounted on extremity of rotor arm - Google Patents

Description

211651 o N.Z. No. 211651 1 April 1985 NEW ZEALAND Patents Act 1953 COMPLETE SPECIFICATION IMPROVEMENTS IN OR RELATING TO CUTTING DEVICES O I, WILLIAM STEVEN GILLANDERS, a New Zealand citizen of Hupara Road, Pakaraka, Moerewa, Northland, New Zealand, do hereby declare the invention for which I pray that a Patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement 211651 This invention relates to cutting devices and in particular to a cutting blade for rotary cutting devices such as lawn oowers and scrub slashers.

A problem with some known rotary cutting devices is that the blade(s) thereof have only one cutting edge which can become worn through contact with grass or other foliage and which can be damaged when striking a stone, tree root or other "obstacle" thereby adversely affecting the cutting efficiency of the cutting device.

An object of this invention is at least to mitigate the problems associated with prior art arrangements.

According to a first aspect, the invention provides a cutting apparatus comprising a rotatable drive member having one or more blades pivotably connected to at least one peripheral region thereof, the or each blade incorporating a peripheral edge at least a section of which forms a cutting edge, a portion of the cutting edge being disposable in a cutting position proud of the drive member, and the blade incorporating an adjustable mounting whereby,in use, altering the mounting of the blade on the drive member disposes a different portion of the cutting edge in the cutting position.

According to a further aspect of this invention there is provided cutting apparatus comprising a rotatable drive member 2 13 JULI987r 211651 incorporating one or more blades pivotally mounted to at least one peripheral region thereof, the or each blade being substantially discoid in configuration incorporating a peripheral edge at least a section of which forms a cutting edge, a first portion of the cutting edge being disposable in a cutting position proud of the drive member and the blade incorporating an adjustable mounting whereby in use, altering the mounting of the blade disposes a further portion of the cutting edge in the cutting position.

Thus the invention is charaterised by providing a cutting device incorporating at least one blade having a cutting edge and an adjustable mounting. Adjustment of the blade mounting disposes an associated portion of the cutting edge into a cutting position, the cutting position being common to each portion of the cutting edge. The blade(s) are deflectable away from the cutting position upon contact with an "obstacle" to minimise wear and damage to the blade(s).

The blade may be extendible into and retractable from the cutting position with respect to the drive member to be at least partially deflectable from the cutting position upon contact with an "obstacle". t In order that the present invention may be more readily understood, and so that further features thereof may be appreciated, embodiments of the invention will be described, by - 3 - ,^'E*>CN. ;,'v -5 ;A t3 JUL 1987 ;211G51 ;way of example, with reference to the accompanying drawings, in which ;Figure 1 illustrates, schematically, one form of cutting apparatus of the present invention; ;Figure 2 illustrates, schematically, another form of cutting apparatus of the invention; ;Figure 3 is a side elevation of the apparatus of Figure 2; and ;Figure 4 illustrates schemmatically a further embodiment of cutting apparatus of the invention. ;Referring to Figure 1, one embodiment of a cutting apparatus of the invention comprises a drive member 1 supporting one or more blades 2. The drive member 1 may be in the form of a rectangular plate or may be a disc, and is rotated by an axial shaft connectable with a motor drive as found on some conventional rotary lawn mowers and scrub slashers. Preferably two or more blades 2 are mounted to peripheral regions of the drive member symmetrically thereabout for purposes of balance. ;The or each blade 2 is substantially discoid in configuration incorporating a peripheral edge 3 at least a section of which forms a cutting edge. The cutting edge preferably extends about the full periphery of the blade. ;- 4 - ;211651 ;The blade 2 incorporates facility for adjustable mounting on the drive member 1. In a first embodiment of the invention, the adjustable mounting preferably comprises a plurality of apertures 4 formed transversely through the blade. The blade is articulately mounted to the drive member by way of a suitable fastener 5, such as a bolt, which locates through a selected one of the blade apertures 4 and through an aperture formed in the peripheral region of the drive member 1 and is secured by a nut (not shown). The blade apertures 4 are preferably disposed in a symmetrical annular arrangement about the discoid blade 2 and are positioned inwardly of the cutting edge. ;In use the drive member is mounted within a mower via a drive shaft 6 connected with drive means, such as an electric motor, for rotation of the drive member about the axis of the drive shaft. In operation, centrifugal rotational force disposes the blade(s) 2 radically outwardly so that a first portion of the cutting edge, indicated generally at 7, protrudes proud of the drive member 1 into a cutting position. When the first portion 7 becomes worn or damaged, the blade 2 can be remounted by a different aperture 4 to present another fresh portion of the cutting edge in the cutting position. It is envisaged that the blade, when it strikes an "obstacle", will deflect away from that "obstacle" against the centrifugal force of rotation. When the "obstacle" has been passed, the centrifugal force of rotation will again bias the blade back into the cutting position. ;5 ;,11 £ A/ > ;211051 ;Accordingly, it is envisaged that the effective cutting life of the blade will be prolonged. ;In an alternative embodiment of the invention illustrated in Figures 2 and 3, a blade 8 having an annular configuration incorporates an inner edge. Each blade mounting preferably comprises a plate 10 fastened to an edge section 11 at a peripheral region of the drive member 1 in planar parallel spaced apart relationship thereto. The plate 10 is preferably mounted at opposing inner and outer radially disposed ends thereof by suitable fasteners 12. ;The blade 8 is captivated between the plate 10 and the drive member 1. The distance between the opposing faces of the plate 10 and the drive member 1 is preferably marginally greater than the depth of the blade 8 to allow limited movement of the blade therebetween. In mounting the blade 8, an outer one of the fasteners 12 locates through the aperture defined by the inner edge 9 thereby captivating the blade 8 to the drive member. The blade 6 is free to move relative to the mounting fastener. The distance between the two fasteners 12 is preferably greater than the sum of the distance between diametrically opposite points on the inner edge 9 and the radial length of the cutting edge of the blade so that when the blade is deflected from the cutting position by an "obstacle" toward the central transverse axis of the drive member, the cutting edge will not contact the inner fastener 12. ;- 6 - ;211651 ;In use, rotation of the drive member 1 forces the blade 8 radically outwardly such that a first portion of the cutting edge is disposed into the cutting position. The blade can rotate about the outer fastener to present different portions of the cutting edge in the cutting position and can be deflected by an "obstacle" in a manner substantially as hereinbefore described. ;In a further development (not shown) a more positive engagement of the blade 9 with the outer fastener 12 is provided to help prevent undue rotational blade movement and thereby reduce resultant overall wear of the cutting edge. For example, a plurality of arcuate indents can be provided on the inner annular edge 9 of the blade 8 in the form of detents. The outer fastener can locate within a detent to restrict rotation of the blade. ;Referring now to Figure 4, an alternative embodiment of a cutting apparatus of the invention comprises a blade 13 mounted on a discoid mounting member 14 which is in turn pivotally mounted on a drive member 1. The blade 13 is connected to the mounting member 14 via a fastener 15 received in one of a plurality of apertures 16 formed peripherally about the member 14. A fastener ;17 is received through another of the apertures 16 and a corresponding aperture in the drive member 1 to fix the mounting member for pivotal movement relative to the drive member. ;The blade 13 may be of any suitable shape and has a cutting edge ;18 formed about at least a part of its periphery. ;-j v^tA,'>C<v. ;- 7 - o\ ;V ^\\ ;- v« ;\ 13 JUL 1987^ ;211651 ;It will be appreciated that in all of the above embodiments a blade arrangement will routinely be provided at each end of the drive member 1 although only one such arrangement is illustrated. ;Finally, it will be appreciated that alterations and modifications may be made to the foregoing without departing from the scope of the invention as defined in the following claims. ;8 ;.4' ;•V ;I *3 J(JL 1987^ > ..

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Claims (17)

211651 WHAT I CLAIM IS:-

1. A cutting apparatus comprising a rotatable drive member having one or more blades pivotally connected to at least one peripheral region thereof, the or each blade incorporating a peripheral edge at least a section of which forms a cutting edge, a portion of the cutting edge being disposable in a cutting position proud of the drive member, and the blade incorporating an adjustable mounting whereby, in use, altering the mounting of the blade on the drive member disposes a different portion of the cutting edge in the cutting position.

2. Apparatus according to claim 1, wherein the blade is extendible into and retractable from the cutting position and is at least partially deflectable from the cutting position upon contact with an obstacle.

3. Apparatus according to claim 1 or claim 2, wherein the blade t has a substantially discoid configuration and is mounted on the i drive member by way of a fastening means received within one of a plurality of apertures provided in the blade, the mounted blade being able to articulate with respect to the drive member. j ?

4. Apparatus according to claim 3 wherein the plurality of apertures are arranged symmetrically about the surface of the blade, the portion of the cutting edge that is disposed in the - 9 - • / ^ : 13JUL1987Z | \ . 1 >. * £ « 211651 cutting position being dependent upon the aperture selected for fastening the blade to the drive member.

5. Apparatus according to any one of claims 1 to 4, wherein the cutting edge is formed throughout the peripheral surface of the blade.

6. Apparatus according to claim 1 or claim 2, wherein the blade is in the form of an annular ring, the cutting edge being formed at the outer periphery of such ring.

7. An apparatus according to claim 6, wherein the blade is retained in position on the drive member by a plate fastened to an edge section of the drive member in planar parallel spaced apart relationship thereto.

8. Apparatus according to claim 7, wherein fastening means for retaining the said plate in position define an axial member about which the annular blade can rotate.

9. Apparatus according to claim 7 or 8, wherein a pair of fastening means are provided for retaining the said plate in position, the fastening means being spaced apart by a distance sufficient to prevent collision of the cutting edge of the blade with a second of the fastening means upon rotation about a first of the fastening means. 10 jv. ' K <v / 'V ■a? 13 JUL 1987£ r\ ^ ~.? i v y • - A 2H651

10. Apparatus according to claim 1 or claim 2, wherein the blade is mounted upon a substantially discoid member which is pivotally attached to the said peripheral region of the drive member.

11. Apparatus comprising a rotatable drive member incorporating one or more blades pivotally mounted to at least one peripheral region thereof, the or each blade being substantially discoid in configuration, incorporating a peripheral edge at least a section of which forms a cutting edge, a portion of the cutting edge being disposable in a cutting position proud of the drive member, and the blade incorporating an adjustable mounting whereby, in use, altering the mounting of the blade disposes a further portion of the cutting edge in the cutting position.

12. Apparatus according to any one of claims 1 to 11, further comprising a drive shaft or like means for connection to driving means.

13. Apparatus according to any one of claims 1 to 12, adapted for use in a lawn mower or like apparatus.

^ 14. Apparatus substantially as herein described with reference ^ to and as shown in Figure 1 of the accompanying drawings.

15. Apparatus substantially as herein described with reference to and as shown in Figures 2 and 3 of the accompanying drawings. - 11 - 211651

16. Apparatus substantially as herein described with reference to and as shown in Figure 4 of the accompanying drawings.

17. A lawn mower or like apparatus including cutting apparatus according to any one of the preceding claims. WILLIAM STEVEN GILLANDERS By Their Attorneys - 12 - si - ' "Tt 13 JUL1987/