JPH0513141Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to a brush cutter that cuts undergrowth, etc. by rotating a rotary blade using a power source such as an engine. The present invention relates to a winding prevention device for a brush cutter that prevents winding.

Conventional technology During actual work using a brush cutter, if tall grass or hard vines are present, these will wrap around the upper and inner sides of the rotary blade, rapidly reducing the rotation of the rotary blade, and even overloading the engine. etc., causing work stoppages and significantly worsening work efficiency. For this reason, attempts have been made to attach a winding prevention device to a brush cutter.

Various types of such winding prevention devices have been proposed in the past. For example, a cutting blade for cutting grass, etc. that is about to wrap around the support rod that supports the rotating blade is integrally attached, and the cutting edge of the cutting blade is oriented in the opposite direction to the rotating direction of the rotating blade. (Utility Model Application No. 77127 of 1971, Utility Model Application No. 37359 of 1982, Utility Model Application No. 207120 of 1982), and those with the cutting edge arranged in a downwardly inclined manner with respect to the rotating direction of the rotary blade (Utility Model Application No. 1983)
No. 49319) have already been proposed, and some have been put into practical use.

Problems to be Solved by the Invention However, if the cutting edge of the cutting blade is simply oriented in the opposite direction to the rotational direction of the rotary blade, or if it is angled downwardly with respect to the rotational direction of the rotary blade, The inventor's experimental research revealed that a sufficient anti-wrapping effect could not be obtained in practice. Also, depending on the mounting position of the cutting blade, there is a high risk that stones etc. flying off the rotating blade may collide with it and cause damage to the cutting blade during work, resulting in poor durability, and the fragments may hit the worker. There were also safety issues.

This invention was developed in view of this technical background, and it has an excellent anti-tangling effect and prevents the cutting blade from being damaged during operation. The present invention provides a sticking prevention device.

Means for Solving the Problems For the above purpose, the inventor conducted extensive research and came to the knowledge that there are conditions for installing the cutting blade that can exhibit an excellent anti-wrapping effect and also do not cause damage. This idea was completed based on this knowledge.

That is, the winding prevention device for a brush cutter according to this invention, as shown with reference to the reference numerals in the drawings, prevents the rotation of a brush cutter equipped with a rotary blade 3 for cutting grass having a spindle 31 in the center. A thin plate-shaped cutting blade 52 for preventing grass, etc. from getting caught is provided above the blade and is supported by a clamping piece so that the cutting edge protrudes. When , the cutting edge 52a is arranged with the cutting edge 52a facing in the opposite direction to the rotational direction of the rotary blade 3, and the cutting edge 52a is arranged almost perpendicularly to the rotating blade 3 when viewed from the front from the same direction as the direction of the cutting edge 52a. At the same time, the lower end of the cutting edge is arranged close to or in contact with the upper surface of the rotary blade, and in plan view, the tangent X at the lower end of the cutting edge of a circle _C1 centered on the axis O of the rotating blade 3 and passing through the lower end of the cutting edge and the cutting edge. The acute angle θ ₁ made with the direction of 52 is 5 to 50°
The blade edge is arranged facing outward in the direction of rotation of the rotary blade 3 at an inclination angle θ ₂ of 10 to 60 degrees with respect to the vertical line Y, when viewed from the side in a direction perpendicular to the direction of the blade edge 52a. The rotary blade 3 is arranged in an upwardly inclined manner, and the radius R of the rotary blade 3 and the support shaft 3 are
It is characterized in that its mounting position is provided under restricted conditions closer to the inner support shaft than the position bisecting the difference from the radius r of 1.

Operation Grass or vines 6 that are not cut by the outer peripheral blade portion 32 of the rotary blade 3 are pulled in the direction of rotation while being caught by the blade portion 32, and as shown in FIG. The cutting edge 52a of the cutting blade 52 is oriented in a direction opposite to the direction of rotation of the cutting blade 52. When viewed from the front in the same direction as the cutting edge 52a, as shown in FIG. Therefore, almost all of the grass or vines caught on the blade portion 32 come into contact with the cutting blade 52. As shown in FIG. 5 when viewed from above, the cutting blade 52 has a tangent line X at the lower end of the cutting edge of a circle _C1 centered on the axis O of the rotary blade 3 passing through the lower end of the cutting edge and the direction of the cutting edge 52a. The acute angle θ ₁ is 5~
Since the blade is oriented outward at an angle of 50 degrees, as shown in the figure, the grass or vines 6 that come into contact with the blade edge 52a
A pressing force is effectively applied to the cutting edge, causing it to bite into the cutting edge, and soft grass etc. can be cut at this stage. In addition, when viewed from the side in a direction perpendicular to the direction, the cutting edge 52a is tilted at an inclination angle θ ₂ of 10 to 60° with respect to the vertical line Y with respect to the rotational direction of the rotary blade 3, as shown in FIG. Since the blades are arranged in an upwardly sloping manner, the hard vines pressed against the cutting edge 52a will be pushed upward along the cutting edge by the tensile force continuously received from the rotating blade, as shown by the chain line in the same figure. The object to be cut is easily cut by the relative pulling action caused by the movement of the object.

Further, as shown in FIG. 7 in a plan view, the cutting blade 52 is installed at a position closer to the inner support shaft than the position that bisects the difference between the radius R of the rotary blade 3 and the radius r of the support shaft 31. is regulated, so even if the rotary blade 3 hits a stone or the like, the risk of it colliding with the cutting blade 52 is extremely reduced.

Moreover, since the cutting blade 52 is in the form of a thin plate, the cutting edge of the cutting blade can be made sharp and its cutting performance is even better.Coupled with the above-mentioned installation conditions of the cutting blade 52, it is possible to cut grass and vines with sharpness. Sharp and easily cut. Moreover, since the cutting blade is supported by the clamping pieces 51, 51, the cutting blade is protected by the clamping pieces.

Embodiment Next, the structure of this invention will be explained based on the embodiment shown in FIGS. 1 to 7.

As shown in Fig. 1, the brush cutter has a support rod 1,
A gear case 2 attached to the tip of this support rod,
It has a disk-shaped rotary blade 3 which has a support shaft 31 in the center and is rotatably supported at the lower end of the gear case 2. Then, the rotational force generated by the power of an engine or the like (not shown) is transmitted to the rotary blade 3 through the shaft housed in the support rod 1 to rotate it, and the blade part 32 provided on the outer periphery of the rotary blade It is used to cut down grass, vines, etc.

A cutting blade holder 4 is provided at the tip of the support rod 1.
A cutting blade unit 5 is attached to the tip of the holder 4 in a detachable manner. The cutting blade holder 4 includes a releasable metal holding piece 41 with a keyhole-shaped cross section fitted into the support rod 1, and a metal holding piece 41 with one end disposed to cover a side piece 41a of the holding piece 41. It has a mounting arm 42 made of aluminum. Then, as shown in FIGS. 1 and 2, by tightening the bolt 43 passing through the side piece 41a of the holding piece 41 and the mounting arm 42 with a nut 44, the holding piece 41 is attached to the support rod 1. , mounting arm 42
are firmly and removably fixed to the holding pieces 41, respectively. Note that 45 shown in FIG. 2 is an adjustment piece for adjusting the difference between the outer diameter of the support rod 1 and the inner diameter of the holding piece 41, and by interposing the adjustment piece 45, the brush cutter can be adjusted. The support rod 1 can be made thinner or thicker depending on the model or the like.
Further, the distal end of the attachment arm 42 extends close to the support shaft 31 of the rotary blade 3, and a unit attachment portion 42a for attaching the cutting blade unit 5 is provided at the distal end. On the other hand, the cutting blade unit 5 has a thin plate-like cutting blade 52 in the shape of a cutting knife between metal clamping pieces 51 that are folded in a folded manner.
is clamped and supported with its razor-sharp cutting edge 52a exposed. The cutting blade unit 5 is inserted into the insertion hole 42a' of the unit mounting part 42a, and the cutting blade unit 5 is inserted into the insertion hole 42a' of the unit mounting part 42a.
It is fixed by the pressing force of a bolt 46 screwed in from the side of a. Therefore, by loosening the bolt 46, the cutting blade unit 5 can be removed or replaced. In this installed state, the cutting blade 52 has its cutting edge 52a facing the rotary blade 3, as shown in FIG. The lower end of the cutting edge 52a is placed as close as possible to or in contact with the upper surface of the rotary blade 3, so that almost all of the grass and vines that try to wrap around the cutting blade 52 are It is assumed that they are in contact with each other. "Almost vertical" here
This means that a slight inclination within about ±10° from the vertical line is allowed. Further, since grass caught on the blade portion 32 of the rotary blade 3 is pulled in the direction of rotation of the rotary blade 3, the cutting edge 52a of the cutting blade 52
is arranged facing in the direction opposite to the rotation direction of the rotary blade 3.

Moreover, in the plan view shown in FIG. 5, the cutting blade 52 is centered on the axis O of the rotary blade 3,
Tangent line X at the lower end of the cutting edge of circle C ₁ passing through the lower end of a
The cutting edge 52a is arranged to face outward, and an acute angle θ ₁ between the tangent X and the direction of the cutting edge 52a is formed.
is defined as 5 to 50°. The reason why this arrangement was made to face outward at a certain angle is as follows. That is, the grass or vines 6 that have not been cut by the outer circumferential blade part 32 of the rotary blade 3 are pulled in the rotational direction while being caught by the blade part 32, and eventually are pulled by the cutting blade 52 as shown in FIG. Although it comes into contact with the cutting edge 52a,
By giving an angle θ ₁ of 5 to 50 degrees, the grass or vines 6 that are about to wrap around the blade edge 52a at an appropriate angle.
This is because the cutting edge intersects with the cutting edge, applies an effective pressing force to the cutting edge, and bites into the cutting edge. However, the angle θ ₁ between the tangent X and the direction of the cutting edge 52a is
If it is less than 5 degrees or more than 50 degrees, the intersection angle between the grass or vine 6 and the blade edge 52a will be inappropriate, and the blade may wrap around the cutting blade unit 5 before being cut, or the blade may slide sideways. It has been experimentally confirmed that this phenomenon occurs, and it becomes impossible to perform sufficient cutting in either case. Tangent line X and cutting edge 52
A particularly preferred angle with the direction of a is 10 to 20 degrees.

Furthermore, the cutting edge of the cutting blade 52 is arranged to be inclined upward with respect to the rotational direction of the rotary blade 3, as shown in FIG. The inclination angle θ ₂ is defined as 10 to 60°. in this way,
The reason why the cutting edge 52a is arranged in an upwardly inclined manner with a constant inclination angle is as follows. That is, the hard tendrils 6 and the like pressed against the cutting edge 52a are pushed diagonally upward along the cutting edge 52a as shown by the chain line in FIG. 6 due to the tensile force received as the rotary blade 3 advances, and the object to be cut is This is because the material is easily cut by the relative pulling action caused by the movement of the material. However, if the inclination angle θ ₂ with respect to the vertical line Y is less than 10°,
Grass, vines, etc. become difficult to move along the blade edge, so the above-mentioned pulling effect is not fully exerted, and the grass and vines wrap around the inside of the rotary blade 3 in the non-cutting state. It has been confirmed through experiments that the pressing force applied to the blade edge 52a becomes weaker, causing the blade to pass through the upper end of the blade edge 52a and get caught on the mounting arm 42, etc., before being completely cut, and also wind around the inside of the rotary blade 3. It was done. A particularly desirable inclination angle of the cutting edge 52a with respect to the vertical line Y is 20 to 35 degrees, most preferably
It is 25-30°.

In addition, the cutting blade 52 is located on the inner support shaft from a position that bisects the difference between the radius R to the tip of the blade portion 32 of the rotary blade 3 and the radius r of the support shaft 31 in a plan view as shown in FIG. Its mounting position is regulated.
In other words, the cutting blade 52 is housed inside a circle C ₂ with a radius (R+r)/2 connecting the two halves of the rotary blade 3 with the center axis O as its center. It is designed to avoid collisions.
Preferably, it is placed as close to the support shaft 31 as possible.

In the brush cutter having the above configuration, grass and vines that are not cut by the outer peripheral blade part 32 of the rotary blade 3 are pulled in the direction of rotation while being caught by the blade part 32.
Eventually, it intersects the cutting edge 52a of the cutting blade 3 at an appropriate angle, receives sufficient pressing force, and bites into it.
Soft grass etc. are cut at this stage. In addition, the hard vines pressed against the cutting edge 52a slide upward along the cutting edge 52a due to the tensile force continuously received from the rotating blade 3, but when viewed from the front from the cutting edge direction, the cutting edge 52a is the rotating blade. Coupled with the fact that it is arranged perpendicular to 3, it slides straight up without skidding sideways, and is easily cut by the relative pulling action caused by the movement of the object to be cut. Moreover, the cutting edge 52a of the cutting blade 52
Since it is sharp, it becomes easier to cut.

In the illustrated embodiment, the cutting blade 52 is provided at only one location, but two or more cutting blades may be arranged at intervals in the circumferential direction to completely prevent wrapping. It's okay.

Effects of the invention As described above, this invention stipulates the installation conditions regarding the direction of the cutting blade, so the cutting blade can remove grass, vines, etc. that try to wrap around the inside of the rotary blade, regardless of its softness or hardness or how it grows. It is possible to efficiently cut grass one after another and prevent it from wrapping, and as a result, there is no reduction in rotation of the rotary blade or stoppage of the engine due to wrapping, making it possible to perform continuous and smooth mowing work. Moreover, since the installation position of the cutting blade is set inward from a certain range, it is possible to reduce the risk of stones, etc. thrown by the rotating blade colliding with the cutting blade, resulting in a highly safe and durable anti-wrapping device. It can be done.

In addition, in this invention, since the cutting blade is in the form of a thin plate, the cutting edge of the cutting blade can be made razor-sharp, so that its cutting performance can be improved. Together,
It is sharp and can cut grass and vines with ease. Moreover, since the cutting blade is supported by the clamping piece with the cutting edge protruding, the cutting blade can be protected by the clamping piece, and the strength is reduced due to the cutting blade being formed into a thin plate shape. This can be supplemented with a clamping piece, resulting in a high-performance anti-wrapping device that has excellent cutting performance, strength, and durability.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing the main parts of the brush cutter, Figure 2 is a sectional view taken along the - line in Figure 1, Figure 3 is a front view of the cutting blade unit, and Figure 4 is a view from the direction of the cutting edge of the cutting blade. 5 is a plan view illustrating the angle of the cutting edge of the cutting blade when viewed from a plane; FIG. 6 is a side view seen from a direction perpendicular to the cutting edge of the cutting blade; FIG.
The figure is a plan view showing the mounting position of the cutting blade in the diametrical direction of the rotary blade. 1... Support rod, 3... Rotating blade, 31... Support shaft,
32...blade portion, 52...cutting blade, 52a...blade tip.

Claims (1)

[Scope of Claim for Utility Model Registration] A brush cutter equipped with a rotary blade for brush cutting having a spindle in the center, supported by a clamping piece with the cutting edge protruding above the rotary blade. A thin plate-shaped cutting blade is provided to prevent grass, etc. from wrapping around the blade, and when the rotating blade is placed horizontally, the cutting blade is arranged with the cutting edge facing in the opposite direction to the rotational direction of the rotating blade, and When viewed from the front in the same direction as the
The cutting edge is arranged almost perpendicularly to the rotating blade, and the lower end of the cutting edge is arranged close to or in contact with the upper surface of the rotating blade, and when viewed from above, the radius of the circle passing through the lower end of the cutting edge is centered on the axis of the rotating blade. The blade is oriented outward so that the acute angle between the tangent at the lower end of the blade and the direction of the blade is 5 to 50 degrees, and the blade edge is 10 to 60 degrees from the vertical line when viewed from the side in a direction perpendicular to the direction of the blade. The support shaft is arranged in an upwardly inclined manner with respect to the rotational direction of the rotary blade at an inclination angle of A device for preventing grass, etc. from getting entangled in a brush cutter, characterized in that the device is installed near the shaft under regulated conditions.