JPH0432909Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention is particularly applicable to a cutting blade unit for a lawn mower, in which a rotary blade and a fixed blade are coaxially superimposed to cut grass etc. by the rotation of the rotary blade. Concerning blade improvement.

<Prior art and its problems> Conventionally, rotary blades of this type of cutting blade unit were disclosed in Japanese Patent Publication No. 51-38610 (hereinafter referred to as the former) and Japanese Patent Publication No. 53-18420 (hereinafter referred to as the latter). It is known that the blade structure (blade shape) is as follows.

The rotary blade of the former cutting blade unit has a cutter with a generally inverted trapezoidal cross section on both sides, which has a blade part (blade surface) on both sides that slides against the blade part (cutting blade) on the periphery of the fixed blade. The cutter has a structure in which the cutter is pivoted between the hanging plates (side plates) that are bent downward and hung down, allowing the cutter to swing between the two. If a distortion occurs such as tilting of the edge of the fixed blade, the cutter will adjust to the distortion and swing, ensuring close contact with the edge of the fixed blade, making it easier to cut grass etc. The former can achieve the desired effect of being able to cut into pieces.

However, in reality, only the front blade part of the cutter located in the rotational direction of the rotary blade acts as a cutting blade that cuts grass etc. by cross-sliding contact with the blade part of the fixed blade periphery, and the rear blade part acts as a cutting blade that cuts grass etc. The blade simply follows the front blade and slides over the blade on the periphery of the fixed blade, and not only does it not function as a cutting blade to cut grass, etc., but the grass, etc. cut from the front blade also If grass gets stuck between the fixed blade and the rear blade, which does not function as a cutting blade, and the grass gets clogged, the front blade will lift up from the blade on the periphery of the fixed blade. ) If the grass is separated and the next grass cannot be cut due to cross-sliding contact with the blade on the periphery of the fixed blade, it may cause uncut grass, or if the cutter with blades on both sides is rotated. Since the structure is such that the fixed blade is attached radially and linearly to the periphery of the frame, not only is it difficult for grass to be taken in between the fixed blade and the blade on the periphery of the frame, but once the grass has been taken in, the edges of each blade slide in a crosswise manner. There was a lot of uncut material that could easily escape along the slope, and the overall cutting efficiency was poor. Furthermore, the structure is such that the cutter is manufactured separately and then attached to the periphery of the rotating frame using a shaft, which makes manufacturing cumbersome and time-consuming.
There were also a number of problems in terms of production costs, including rising costs.

On the other hand, in the case of the rotary blade of the latter cutting blade unit,
Since the structure has a blade only on the front side located in the rotating direction of the rotary blade, unlike the former rotary blade, there is no problem of cut grass clogging and floating up from the blade around the fixed blade, but still. Like the former rotary blade, it has a structure in which the blade part is formed radially and linearly on the periphery, so not only is it difficult to take in grass between the blade part on the periphery of the fixed blade, but also the grass that has been taken in may cross each other. There is a lot of uncut material that easily escapes along the edges of each blade that slides into contact with the blade, and the overall cutting efficiency is poor.

Therefore, the applicant of the present application proposed a concave arc-shaped blade which is curved in the direction of rotation, and has a blade tip portion from the curved central portion as a grass-taking portion, and a portion connected from the curved central portion to the peripheral edge as a grass-extruding portion. A cutting blade unit consisting of a rotary blade having a circular edge formed on its periphery, and a fixed blade having a plurality of convex blade parts protruding from its periphery that make sliding contact with the concave concave circular blade part of the rotary blade, coaxially stacked on top of each other. was first developed and offered (in 1983)
-Refer to Publication No. 163119).

<Problem to be solved by the invention> The present invention was made in view of the conventional problem, and the technical problem to be solved is to reduce the sliding force with the convex blade part on the periphery of the fixed blade. The rotary blade is coaxial with the fixed blade, which can be kept constant at all times, and can reliably cut grass, etc., without leaving any uncut parts between the convex blade and the convex blade, and can be manufactured easily and inexpensively. The purpose of the present invention is to provide a cutting blade unit formed by superimposing the blades on the blades.

<Means for Achieving the Technical Problem> The technical means taken by the present invention to achieve the above object is to curve the blade in the direction of rotation, and to make the tip of the blade from the center of the curve serve as the weed-taking part. A rotary blade with a concave arc-shaped blade part formed on the periphery, the part of which extends from the curved center part to the periphery as the grass extrusion part, and a convex blade part on the periphery that is in sliding contact with the concave arc-shaped blade part of the rotary blade. In the cutting blade unit, which is formed by coaxially overlapping fixed blades with a large number of protruding blades, the periphery of the rotary blade is raised to form a shallow dish shape, and the top end surface is formed on the periphery. A blade forming part that opens in a substantially V-shape or U-shape on the side is provided, and the rising height of the rising part of the peripheral edge other than the rising part on one side of the blade forming part located in the rotation direction of the rotary blade is increased by one step. It is characterized by being formed low.

<Example> An example of the present invention will be described based on the drawings.
The cutting blade unit A is composed of a rotary blade 1 and a fixed blade 2 which are coaxially stacked on top of each other. At the same time, the rotary blade 1 is fixed to the protruding drive shaft 3 with bolts 4, and the concave arc-shaped blade portion 5 (described later) of the rotary blade 1 is attached to each blade portion 6 on the periphery of the fixed blade 2. The blades are brought into elastic contact with each other, and the rotary blade 1 is rotated by the power from the drive machine to cut and mow the grass.

The rotary blade 1 is integrally formed by press working, and only the concave arc-shaped blade part 5 (described later) is polished in post-processing, and a rising part 7 of a desired height is formed on the periphery of the rotary blade 1.
The blade is bent into a slanted shape and raised into a shallow dish-like triangular shape or pentagonal shape, etc. In the drawing, it is formed into a triangular shape to improve the rigidity of the entire blade, that is, it is easier to bend when rotating compared to a flat plate. The blade part is formed into a shallow dish-shaped structure in which the entire blade is given rigidity without any risk of deformation by the peripheral edge rising part 7, and the blade part has a top end opening at the periphery in a side surface approximately in a V-shape or a U-shape. A forming portion 8 is provided. The blade forming portion 8 is located in the rotation direction X of the rotary blade 1.
One side (front side) excluding the rising part of the other side (rear side)
The rising height of the peripheral edge rising portion 7 is made lower in order to form a discharge gap 9 in which cut grass, etc. can be discharged without clogging between it and the fixed blade 2. A concave arc-shaped blade part 5 is formed on each of the convex blade parts 6 in a partial contact structure so that the concave arc-shaped blade part 5 always slides against the convex blade part 6 with a constant sliding force.

The concave arc-shaped blade part 5 has a generally concave shape with one side rising part formed one step higher than the rising height of the peripheral edge rising part 7 of the blade part forming part 8 on the peripheral edge of the rotary blade 1 facing in the rotation direction X of the rotary blade 1. The grass-taking portion 5a is curved from the center of the curve to the tip of the blade.
The grass extrusion portion 5b extends from the curved central portion to a portion connected to the peripheral edge rising portion 7 via a stepped portion. That is, the grass is cut while being taken in between the blade part 6 of the fixed blade 2 at the grass intake part 5a together with each convex blade part 6 on the peripheral edge of the fixed blade 2, and the grass is cut while being taken in between the blade part 6 of the fixed blade 2 at the grass extrusion part 5b. It cuts the grass caught between it and the convex blade part 6 while pushing it out.

The fixed blade 2 is formed into a flat plate shape and has a plurality of convex blades 6 on its periphery at a substantially constant scissoring angle (intersection) effective for scissoring with the concave arc-shaped blade 5 of the rotary blade 1. The rotary blade 1 has a plurality of holes 10 formed on its inner side to discharge grass that has entered between the rotary blade 1 and the rotary blade 1.

According to the cutting blade unit A of this embodiment,
The peripheral edge rising portion 7 has a shallow dish-shaped structure that gives the entire blade rigidity without any risk of deformation such as deflection during rotation, and the triangular rotary blade 1 has three side surfaces approximately V-shaped or U-shaped on the periphery. The opening blade forming part 8 is formed to be one step higher than the rising height of the peripheral edge rising part 7 located on the rear side with respect to the rotational direction of the rotary blade 1, and has a substantially concave shape toward the rotational direction X of the rotary blade 1. The blade structure includes a curved concave arc-shaped blade part 5, which increases the strength of the fixed blade 2 so that it will not be damaged immediately even if it hits gravel, rocks, etc. scattered on the ground during mowing work. By closely overlapping the fixed blade 2
The sliding force against each of the convex blades 6 on the periphery is always kept constant due to the partial contact structure. And rotary blade 1
When the blade is rotated, when it comes into cross-sliding contact with each of the convex blades 6 on the periphery of the fixed blade 2, the grass is reliably taken in between the grass-taking portion 5a and the convex blades 6 on the periphery of the fixed blade 2, and the grass is cut. At the grass extrusion part 5b, the fixed blade 2
A rising part of the periphery behind the concave arc-shaped blade part 5 which cuts grass caught between the convex blade part 6 on the periphery and the concave arc-shaped blade part 5 while pushing out the grass and cutting it as surely as you would with scissors, and letting the cut grass escape one step lower. 7 and the fixed blade 2, and is smoothly discharged to the outside from the discharge gap 9 formed between the peripheral edge rising portion 7 and the fixed blade 2. Therefore, the concave arc-shaped blade portion 5 on the circumferential edge of the rotary blade 1 does not lift up and separate from each convex blade portion 6 on the circumferential edge of the fixed blade 2 due to grass clogging such as cut grass, and each of the concave arc-shaped blade portions on the circumferential edge of the fixed blade 2 The sliding contact state of the concave arc-shaped blade part 5 on the circumference of the rotary blade 1 with the convex blade part 6 is a shallow dish of the rotary blade 1 in which the entire blade is given rigidity without any possibility of deformation such as bending during rotation. Due to the shape structure and the partial contact structure of the concave arc-shaped blade part 5 with the convex blade part 6, it is always kept constant, and mowing work can be carried out efficiently without leaving any mowing residue.

<Effects of the invention> Since the cutting blade unit of the invention is constructed as described above, it has the following effects.

The rotary blade has a raised peripheral edge to form a shallow dish shape that gives rigidity to the entire blade, and the peripheral edge has a blade forming part whose top end is opened in a side surface approximately V-shaped or U-shaped to increase strength. A concave arc-shaped blade part that is provided so that the rising part on one side of the blade forming part located in the rotation direction is one step higher than the rising height of the other rising part of the peripheral edge and slides into opposing sliding contact with each convex blade part of the peripheral edge of the fixed blade. The blade has a partial contact structure in which only the concave arc-shaped blade comes into contact with the fixed blade, and the rising edge of the periphery excluding the concave arc-shaped blade is formed one step lower to form a discharge gap between the concave arc-shaped blade and the fixed blade for discharging grass. Therefore, there is no risk of the concave arc-shaped blade part on the periphery of the rotary blade lifting up and separating from each convex blade part on the periphery of the fixed blade due to grass clogging such as cut grass. The blade has a shallow dish-shaped structure that gives the entire blade a rigidity that does not cause any risk of deformation such as deflection during rotation, and it is made one step higher than the rising height of the other peripheral edges and curved toward the direction of rotation. Due to the partial contact structure of the fixed blade peripheral edge of the concave arc-shaped blade portion with the convex blade portion, the sliding force with the convex blade portion can be kept constant at all times to reliably cut grass, etc. Therefore, the sliding force of the concave arc-shaped blade part on the periphery of the rotary blade against each convex blade part on the periphery of the fixed blade can be kept constant at all times, and the grass can be efficiently cut without leaving any uncut parts.
The cut grass can be smoothly discharged outside from the discharge gap without accumulating in the shallow dish-shaped rotary blade.

The peripheral edge rising part of the rotary blade, including the peripheral edge forming part, can be integrally formed by press working, and only the concave arc-shaped blade part, which is formed one step higher than the peripheral edge rising part, is subjected to post-processing. Since it can be manufactured by grinding and polishing, it is extremely easy to manufacture and can be provided at low cost. In addition, since all the concave arc-shaped blades on the periphery of the rotary blade are located on the same plane, polishing work after use can be easily performed.

Since the concave arc-shaped blade formed in the blade forming part on the periphery of the rotary blade is curved into a substantially concave shape toward the direction of rotation, even the tip of the blade (weed-taking part) The grass can be cut while being taken in between the blade and the convex blade part on the periphery of the fixed blade, making it possible to cut the grass efficiently.

[Brief explanation of drawings]

The drawings show an embodiment of the cutting blade unit for a lawn mower according to the present invention, FIG. 1 is a plan view, FIG. 2 is a longitudinal side view of the same,
FIG. 3 is a perspective view showing the rotary blade. In addition, in the figure, A...Mowing blade unit, 1...Rotating blade, 2...Fixed blade, 5...Concave arc-shaped blade part, 6...Convex blade part, 7
... Rising portion, 8... Blade forming portion, 9... Discharge gap.

Claims (1)

[Scope of utility model registration request] A concave arc-shaped blade part is formed on the periphery, which is curved in the direction of rotation, and the tip part of the blade part from the curved center part serves as the grass intake part, and the part connected from the curved center part to the periphery serves as the grass extrusion part. a rotary blade; a fixed blade having a plurality of convex blade portions protruding from its periphery that are in sliding contact with the concave arc-shaped blade portion of the rotary blade;
In a cutting blade unit formed by coaxially stacking the rotary blades, the peripheral edge of the rotary blade is raised to form the rotary blade into a shallow dish shape, and the top end surface is approximately V-shaped or U-shaped on the side. A grass mower characterized in that a blade forming part that opens is provided, and the rising height of the rising part of the peripheral edge other than the rising part on one side of the blade forming part located in the rotation direction of the rotary blade is formed to be one step lower. Mower blade unit.