CUTTING BLADE FOR LAWN MOWER

Abstract

A cutting blade for lawn mower is described, that is made up of a generally flat metal shape bar (A) that has cutting edges (B) that extend for the entire length of the same metal shape bar. At the ends of the metal shape bar (A) a pair of collecting fins (C) is provided that are bent helicoidally with respect to the general plane of the metal shape. In position adjacent to said collecting fins (C) a pair of mulching fins (D) bent in sense opposite to the collecting fins (C) are provided. Flat portions (E) connect said mulching fins (D) to a central area (F) destined to the attachment of the blade to a motorized shaft. <IMAGE>

Description

DESCRIPTION of the industrial utility model entitled: H 4 HOV 2001 “Cutting blade for lawnmower” rvl II year I in the name of: CASTELGARDEN SpA ...» MI 2001 U 0 0 0 6 0 4 The present invention concerns a cutting blade for a lawnmower, with the latter term meaning both lawnmowers pushed by the driver and those with a seated driver (normally called tractors). Rotating inside a casing called the cutting deck, the aforementioned blade has the task of not only cutting but also of conveying the cut grass towards an outlet on the cutting deck, to which a rigid grass collection bag is usually, but not necessarily, connected. In some cases, it is possible to close the outlet, forcing the grass to remain inside the casing for so-called mulching or shredding, i.e. the division of the grass into small pieces which are then discharged onto the ground. If it only needs to cut and convey the blade, it has a pair of collection fins at its ends equipped with respective sharp edges and bent with respect to the general plane of the blade in such a way as to drag the cut grass and convey it towards the exit mouth of the cutting deck. If the mulching action is also provided, the blade also has, more towards the center of the blade, one or more pairs of shredding fins bent in the opposite direction to the collection fins with the aim of shredding the cut grass remaining on the cutting deck. Alternatively, the mulching action can be performed by a specific blade other than Dr. Ing. Enrico Mittler that of cutting and harvesting. Current dual-purpose blades have the disadvantage of not providing optimal collection and mulching functions. They are also noisy, and are not easy and cost-effective to manufacture. The aim of this invention was therefore to create a cutting blade for a lawnmower, having the dual function of collecting and shredding the cut grass, which offers maximum performance and also has the advantage of low noise and that of being easier and more economical to construct. In accordance with the invention, this object has been achieved with a cutting blade characterized by the fact that it is formed by a generally flat metal profile having cutting edges that extend along the entire length of the profile itself, a pair of collection fins provided at the ends of the profile and bent helically with respect to the general plane of the profile, a pair of shredding fins adjacent to said collection fins and bent in the opposite direction to them, a central area for attachment of the blade to a motorized shaft and flat connecting portions between said shredding fins and said attachment area. It was found that by appropriately choosing the folding angles and heights of the collection and shredding fins and their length proportions, a cutting blade is obtained that is capable of performing both collection and shredding actions, as well as cutting, with excellent results and features reduced noise. Furthermore, the creation of cutting edges along the entire length of the profile makes the manufacture of the blade easier and more economical. -3 Dr. Ing. Enrico Mittler The characteristics of the present invention will be better understood through the following detailed description of an example of its practical embodiment illustrated in the attached drawings, in which: Figure 1 shows a top plan view of the cutting blade according to the invention; Figure 2 shows the same blade in plan view from below; Figure 3 shows the same blade in front view; Figure 4 shows the same blade seen from the right and left with respect to Figure 1; Figure 5 shows the same blade seen in section along the VV line of Figure 1. The cutting blade illustrated in the drawings is made up of a metal profile A, generally flat, which has cutting edges B that extend along the entire length of the profile itself. At the two ends of the metal profile there is a pair of collection fins C bent helically with respect to the general plane of the belt (fig. 4)· Adjacent to the collection fins C, more towards the centre of the profile, there is a pair of shredding fins D bent linearly in the opposite direction to them. Finally, flat portions E are provided that connect the shredding fins D to a central area F intended for attaching the blade to a motorized shaft. The central area F is equipped with holes G and H for fixing the blade. From the drawings it is possible to detect the preferable proportions chosen for the blade. -4Dr. Ing. Enrico Mittler cutting and its parts. As can be seen, the blade preferably has 37 mm long and 22.2 mm high C-shaped collection fins with an internal bending radius of 35 mm, a final bending angle of 43°, and an initial bending angle of 7°. The shredding fins D in turn have a 29 mm long flat central section that is 25 mm from the adjacent collection fin C and connects at the two ends at an 18° angle. They also have a bending angle of 8°, in the opposite direction to the collection fins C. The cutting edges B finally have a cutting angle of 30°. The other dimensions indicated in the drawings are purely indicative and vary from blade to blade.

Claims

1. Cutting blade for lawnmower, characterised by the fact that it is made up of a generally flat metal profile (A) which has cutting edges (B) which extend along the entire length of the profile itself, a pair of collection fins (C) provided at the ends of the profile (A) and bent helically with respect to the general plane of the profile, a pair of shredding fins (D) adjacent to said collection fins (C) and bent in the opposite direction to them, a central area (F) for attachment of the blade to a motorised shaft and flat portions (E) for connecting said shredding fins (D) and said attachment area (F).

2. Cutting blade according to claim 1, characterised in that said collection fins (C) have a length of approximately 37 mm, a height of approximately 22 mm with an internal curvature radius of approximately 35 mm, a final bending angle of approximately 43°, an initial bending angle of approximately 7°.

3. Cutting blade according to claim 2, characterised in that said shredding fins (D) have a flat central section approximately 29 mm long which is approximately 25 mm from the adjacent collection fin (C) and connects at the two ends with an angle of approximately 18°.

4. Cutting blade according to claim 3, characterised in that said shredding fins (D) have a bending angle of approximately 8°.

5. Cutting blade according to claim 1, characterised in that said cutting edges (B) have a cutting angle of approximately 30°.