JP3208462U - Brush blade for brush cutter - Google Patents

Abstract

The present invention provides a rotary blade for a brush cutter that is further reduced in weight while ensuring strength to withstand use. SOLUTION: A plurality of lightweight holes 16 having a plane-fillable shape are continuously provided between a central portion 10 and a blade portion 14 of a rotary blade 2 so as to be plane-filled, thereby reducing the weight while maintaining the strength of the rotary blade. And improved shock absorption. [Selection] Figure 1

Description

  The present invention relates to a metal rotary blade mounted on a brush cutter.

In a general brush cutter, an operator puts a handle on the shoulder of a belt attached to the brush cutter body so that the rotary blade attached to the tip of the operation shaft with a hook-shaped handle moves left and right along the ground. By moving it, the grass is reaped.
From such a working mode, the weight of the rotary blade at the tip of the brush cutter affects the load on the body during the work.

Therefore, in order to reduce the weight of the rotary blade, a utility model registration No. 3124220 publicity (hereinafter referred to as “Patent Document 1”) has been proposed in which a hole is provided in a disk-shaped body.
However, in the circular hole like patent document 1, a hole and a hole cannot be made to adjoin and there existed a limit in weight reduction.
Moreover, although it is possible to provide a hole so that the remaining part has a shape like an umbrella bone, the strength of the rotary blade cannot withstand use and is not practical.

Utility Model Registration No. 3124220

  Then, this invention makes it a subject to provide the rotary blade for brush cutters reduced in weight, ensuring the intensity | strength which can be used.

  The present invention for solving this problem is characterized in that a plurality of light-weight holes that are continuous in a form that can ensure strength are provided between the attachment hole of the rotary blade and the blade portion.

  That is, the rotary blade for a brush cutter according to the first invention has a disc-shaped base metal formed of a metal plate and a mounting hole for the rotary shaft of the brush cutter formed at the center of the base metal. A central portion, a blade portion continuously formed on the outer peripheral edge of the base metal, and a hole portion having a plurality of lightweight holes formed between the central portion and the blade portion; A rotary blade for a brush cutter, wherein the rotary blade is a polygon that can be filled in a plane, and a plurality of light-weight holes are continuously provided in a plane-filled manner.

Planar filling refers to laying a flat surface without any gaps, and there are three polygons, triangular, quadrangular, and hexagonal, that can be filled with the same shape.
With these three polygonal light-weight holes, a plurality of light-weight holes can be continuously provided in a form in which only the outer periphery of the light-weight hole is left in a mesh shape.
Among these, the shape of the lightweight hole is preferably a triangle or a hexagon. This is because triangles and hexagons have strength against external forces.

  The rotary blade for a brush cutter according to the second invention is characterized in that the shape of the polygon that can be filled in the plane according to the first invention is a regular hexagon.

If a lightweight hole having a polygonal shape that can be flat-filled is formed in the base of a rotary blade for a brush cutter that is plate-like, weight reduction can be realized without significantly reducing the strength. And if the number of lightweight holes is increased, the frame structure by the base metal which only forms the circumference | surroundings of a lightweight hole will remain finally.
At this time, if the lightweight hole is made smaller, the strength is increased, but the amount of the base metal per unit area is increased. Therefore, how to open a lightweight hole that keeps the area of the lightweight hole constant and minimizes the amount of base metal, that is, what figure has the shortest circumferential length of the lightweight hole by plane filling with a figure of the same area? And the figure becomes a regular hexagon.

Thus, when providing the lightweight hole of the same area continuously with the base metal of a rotary blade, it turns out that the weight can be most reduced by making the shape of the lightweight hole into a regular hexagon.
Further, regular hexagons can be filled in a plane, and when a force is applied from a certain direction, the impact is dispersed and transmitted to the other five sides.
This characteristic makes it possible to reduce the weight and improve the impact absorbing power while securing the strength of the rotary blade.

  Furthermore, the rotary blade for a brush cutter according to the third aspect of the present invention is the rotary blade according to the first or second aspect of the present invention, wherein the ratio of the total area of the plurality of lightweight holes to the area of the circumscribed circle of the rotary blade is 20%. It is characterized by being -35%.

If the width of the frame structure formed by the base metal between the lightweight hole and the adjacent lightweight hole is made the same, the strength of the rotary blade increases as the lightweight hole becomes smaller, but the frame structure with the remaining base metal The total weight of increases.
Conversely, the larger the lightweight hole, the less the total weight of the frame structure by the remaining base metal, but the strength of the rotary blade is reduced.
That is, in the present invention in which light-weight holes having a shape that can be filled in a plane are continuously provided, the total area of the light-weight holes affects the total weight and strength of the rotary blade.

By the way, in this invention, since the shape of a lightweight hole is a polygon which can be plane-filled, the total area of a lightweight hole can be easily set by changing the magnitude | size of a lightweight hole.
Therefore, as a result of various experiments, if the total area of the plurality of lightweight holes is set to be 20% to 35% of the area of the circumscribed circle of the rotary blade, the rotary blade without the lightweight holes is maintained while maintaining the strength to withstand use. It was found that a maximum weight reduction of 30% can be realized.

  Since the rotary blade of the present invention is continuously provided in a mode in which a lightweight hole having a shape that can be planarly filled is provided on the base metal in a plane-filled manner, the weight can be reduced while maintaining the strength.

  In addition, by making the shape of the lightweight hole a regular hexagon, the shock absorption capacity is increased, and the shocking and unpleasant impact sound when the rotating blade hits stone, concrete, or metal during work is reduced, and the cutting edge Long service life is possible.

It is a top view of the rotary blade of this invention. Example 1 It is a side view of the rotary blade of this invention. Example 1 It is a top view of the existing rotary blade. (Comparative Example 1) It is a top view of the existing rotary blade. (Comparative Example 2) It is explanatory drawing of total weight calculation of the rotary blade of this invention. Example 1 It is explanatory drawing of total weight calculation of the rotary blade for a comparison. (Comparative Example 3) It is explanatory drawing of total weight calculation of the rotary blade of this invention. (Example 2) It is explanatory drawing of total weight calculation of the rotary blade for a comparison. (Comparative Example 2)

  The rotary blade of the present invention has a plurality of light-weight holes continuously provided in a form of plane filling between a central portion and a blade portion of a general brush cutter for brush cutter. Since the light-weight holes are continuously provided in a plane-filled form, a net-like base metal remains around the light-weight holes.

  Examples of the present invention will be described below.

  A first embodiment of the present invention (hereinafter referred to as “embodiment 1”) will be described. 1 and 2 are a plan view and a side view of the first embodiment.

As shown in FIG. 1, the rotary blade 2 has a disc shape formed of a metal plate, and is composed of a center portion 10, an outer hole portion 12, and an outer blade portion 14. Yes. A tip 8 is attached to the blade portion 14. The diameter of the rotary blade 2 is 255 mm.
The central portion 10 is flat with a predetermined thickness (1.25 mm) and has a mounting hole 6 with a diameter of 25.4 mm for mounting on the rotary shaft of the brush cutter at the center.

  A hole 12 having a honeycomb-like shape in which a plurality of regular hexagonal lightweight holes 16 are provided is formed around the attachment hole 6. The lightweight holes 16 have a regular hexagonal shape with an interval between opposing sides of 7 mm, and are provided with 378 in a form of plane filling, all penetrating the base metal 4.

FIG. 3 is a plan view of an existing rotary blade (hereinafter referred to as “Comparative Example 1”). The only difference from Example 1 is the presence or absence of lightweight holes.
FIG. 4 is a plan view of another existing rotary blade (hereinafter referred to as “Comparative Example 2”).
In Comparative Example 2, from the center toward the outer edge, 30 pieces having a diameter of 30 mm, 30 pieces having a diameter of 5.5 mm, 30 pieces having a diameter of 6.0 mm, 30 pieces having a diameter of 6.5 mm, and 30 pieces having a diameter of 7.0 mm. A total of 270 light-weight holes, 30 pieces having a diameter of 7.5 mm, 60 pieces having a diameter of 8.0 mm, and 30 pieces having a diameter of 8.5 mm are provided.

“Experiment 1”
Here, an impact test was performed using the rotary blades of Example 1, Comparative Example 1, and Comparative Example 2, and the impact sound at that time was compared.
The impact test method was performed by applying a rotating blade rotated at a predetermined speed to a concrete block according to “Impact test method for carbide cutting blade for brush cutter (Nichinoko standard: 0004-200X)”. The load when the rotary blade is applied to the concrete block is 5 kgf.
For the three rotary blades, the average value of the impact sound measured by performing the same test 50 times was 124.8 dB in Example 1, 127.6 dB in Comparative Example 2, and 128.9 dB in Comparative Example 1.
Since Example 1 has an impact sound that is 4.1 dB lower than that of Comparative Example 1 and 2.8 dB lower than that of Comparative Example 2, the structure of the hexagonal mesh-shaped hole portion provides excellent shock absorption. Proved to be.

  The characteristic that Example 1 is excellent in shock absorption is that not only can the unpleasant impact sound when the rotating blade hits stone or concrete be reduced in use, but also the deterioration of the blade edge due to contact with foreign matter and the chip Demonstrates the effect of preventing dropout.

"Experiment 2"
Next, a load test in the diameter direction of the rotary blade was performed on Example 1, Comparative Example 1, and Comparative Example 2.
The maximum displacement when a load of 1000 N was applied in the diameter direction of the rotary blade was 15.74 mm in Example 1, 7.69 mm in Comparative Example 2, and 0.39 mm in Comparative Example 1.
In addition, none of the rotary blades buckled in this experiment and returned to their original shape when the load was released.

“Experiment 3”
Next, for the same rotary blade, the load applied in the diameter direction of the rotary blade when a displacement of 5 mm occurred was measured.
As a result, Example 1 was 650.5N, Comparative Example 2 was 798.8N, and Comparative Example 1 was 1000N or more. From this, it was found that Example 1 was well bent with a small force.

"Comparison of total weight of rotary blades"
5-8 is explanatory drawing of the total weight calculation of Examples 1-2 of this invention, and Comparative Examples 2-3.
First, the total weight is compared with reference to FIG. 5 and FIG.
FIG. 5 shows the first embodiment. The first embodiment is a rotary blade in which 378 regular hexagonal lightweight holes having a distance between opposite sides of 7 mm are plane-filled. On the other hand, FIG. 6 shows a rotary blade (hereinafter referred to as “Comparative Example 3”) provided with 378 circular lightweight holes having a diameter of 7 mm.
As shown in FIGS. 5 and 6, Example 1 has a total weight of 339 g, and Comparative Example 3 has a total weight of 354 g. Since the total weight of the comparative example 1 which does not have a lightweight hole is 496g, compared with the conventional rotary blade which does not have a lightweight hole, Example 1 is implement | achieved 32% of weight reduction.
It can also be seen that the regular hexagonal lightweight hole is superior in weight reduction to the circular lightweight hole.

Next, the total weight of the rotary blade will be compared with reference to FIG. 7 and FIG.
FIG. 8 shows a rotary blade (Comparative Example 2) distributed in the market in which 270 circular lightweight holes having different diameters are sequentially arranged. FIG. 7 shows a rotary blade (hereinafter referred to as “Example 2”) in which 270 regular hexagons having different sizes from the center to the outer edge are sequentially arranged in the same manner as in Comparative Example 2.
7 and 8, the total weight of Example 2 is 384 g, and the total weight of Comparative Example 2 is 395 g.
In Example 2, the total weight is lighter than that of Comparative Example 2 which is a conventional product, and the weight is reduced by 23% compared to Comparative Example 1.

  The present invention is not limited to a rotary blade (tip saw) with a tip mounted on the outer periphery of a disk-shaped base metal, but is also used for cutting off vegetation including a rotary blade whose blade edge is formed integrally with the base metal. Available for all rotating blades.

2 Rotary blade 4 Base metal 6 Mounting hole
8 Chip 10 Center part 12 Hole part 14 Blade part 16 Lightweight hole

Claims (3)

  A disc-shaped base metal formed of a metal plate, a central portion having a mounting hole for a rotary shaft of a brush cutter formed at the center of the base metal, and an outer peripheral edge of the base metal are formed continuously. A plurality of lightweight holes formed between the blade portion and the center portion, and the shape of the plurality of lightweight holes is a polygon that can be plane-filled. A rotary blade for a brush cutter, wherein light-weight holes are continuously provided in a manner of filling the hole portion with a flat surface.   The rotary blade for a brush cutter according to claim 1, wherein the shape of the polygon that can be filled in a plane is a regular hexagon.   The rotary blade for a brush cutter according to claim 1 or 2, wherein a ratio of a total area of the plurality of lightweight holes to an area of a circumscribed circle of the rotary blade is 20% to 35%.

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