JPH09154363A - Mowing circular saw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mowing circular saw not inducing breaking or fall off of a chip even in contact of a tooth part with a hard material in using. SOLUTION: This mowing circular saw has first teeth 12 and second teeth 13 alternately projecting along an outer edge of a disk-like base plate 11. The first teeth are formed continuously to the base plate with the same material as the base plate containing their blade parts and have sets inclined to outside of one face of the base plate, and the blade parts of the second teeth are formed by soldering chips 19 made of a comented carbide. In the mowing circular saw, a tip part wherein the first teeth project to outside in the radial direction of the base plate is projected to outside in the radial direction of the base plate by the same degree as the tip part of the second teeth, the first teeth have laterally cutting blades 14 and the tip part of the first teeth have a part 15 wherein the laterally-cutting blade is not existed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mowing circular saw.

[0002]

2. Description of the Related Art Most cutting blades of recent grass cutting circular saws are made of cemented carbide chips in consideration of wear resistance. The mowing circular saw has irregularities formed at a predetermined pitch on the outer peripheral edge of a disk-shaped substrate made of tool steel, and a recess for attaching a chip is provided on the convex part, and the chip is brazed to the recess. It is common to have An example is shown in FIG. In the figure, 1 and 2 are chips made of cemented carbide, 3 and 4 are substrates made of tool steel, 5 and 6 are brazing surfaces, and θ1 is a horizontal scooping angle, usually about 5 to 8 °.
FIG. 4 shows a grass cutting circular saw 7 shown in FIGS.
Regarding the grass cutting circular saw 8 shown in (c) and (d), the grass cutting circular saw 8 has a larger brazing area as seen from the front shape, and is superior in that the tip is less likely to fall off. The arrow in the figure indicates the direction of rotation during use.

[0003]

Generally, a mowing circular saw is
In use, not only grass always hits, but hard things such as stone, concrete, or metal pieces may hit, and in such cases a large impact is applied to the tip, so there is a problem that the tip is easily chipped. Yes, again
If the brazing area between the tip and the base metal is small, there is a problem that the brazing part comes off and the tip falls off. SUMMARY OF THE INVENTION It is an object of the present invention to prevent a chip from being chipped or falling off even if a tooth portion comes into contact with a hard object during use of a mowing circular saw.

[0004]

Means for Solving the Problems In the means of the present invention, first teeth and second teeth are alternately projected along the outer edge of a disk-shaped substrate, the first teeth being the blades of the blade. Part of the second tooth is made of the same material as the substrate and is continuously formed on the substrate and has a crest inclined to the outside of one surface of the substrate. It is characterized in that it is formed by brazing a chip.

Most of the time, the circular cutting saw is used so that the surface of the base plate is substantially parallel to the ground, and the side where the first tooth protrudes by the digging is used as the lower surface.
When a circular saw comes into contact with a stone or a metal piece on the surface of the earth, the tip portion of the first tooth comes into contact with the second tooth due to the clam, and the second tooth is difficult to come into contact with. Therefore, since the first tooth protects the second tooth, the second tooth does not chip or fall off the cemented carbide tip of the blade portion, and maintains good sharpness for a long time. Since the first tooth is made of the same tool steel as the substrate, it is more easily worn than the second tooth brazed with a cemented carbide tip, but it is less likely to chip. Therefore, the first tooth wears but retains its protective effect for a long time.

In the above-mentioned means, the first tooth has a tip portion protruding outward in the radial direction of the substrate, and the tip portion of the second tooth is provided so as to protrude outward in the radial direction of the substrate to the same extent. Good to do. The protruding portion of the first tooth has a greater protective effect on the second tooth when it is more protruding, but if it is protruding too much, the mowing function is deteriorated. That is, grass that cannot be mowed by the first tooth will escape to the outside of the substrate and be mowed by the next second tooth, but the first tooth is slightly protruding from the second tooth. This makes it harder to get onto the second tooth and leaves some of it uncut. According to the experiment, when the first tooth is slightly protruded from the second tooth, it is almost impossible to understand by simply observing the cutting mark. It was transmitted as a slippery feeling, and it was found that the sharpness was not necessarily sufficient. First
The feeling of slipping is eliminated by making the protrusions of the second tooth and the tooth of the same degree.

In the above means, the first tooth preferably has a lateral cutting edge. With this configuration, the first
Since the tooth is made of the same material as the substrate, that is, generally tool steel, it is more easily worn than the cemented carbide chip, but the initial sharpness during the usable period without re-polishing is extremely good. When the wear of the lateral cutting edge of the first tooth progresses, the sharpness is lower than the initial sharpness, but the user does not feel that the sharpness is lower than that of a normal good mowing circular saw. It was judged that the sharpness was good even when the condition of the ground after cutting the grass was observed.

In the above-mentioned means, it is preferable that the first tooth is provided with a portion having no lateral cutting edge at its tip. With this configuration, the portion where the cutting edge at the tip of the first tooth does not exist is the portion that is most likely to come into contact with the foreign matter on the ground surface side during use, but compared to the case where a horizontal cutting edge is provided up to the tip, Because there is no scooping angle,
High strength and wear resistance. Therefore, since the tip portion of the first tooth is less likely to wear, the protection period of the second tooth becomes longer.

[0009]

1 to 3 show an embodiment of the present invention.
This will be described with reference to FIG. As shown in FIG. 1, this circular grass cutting saw 10 has a large number of first teeth 12 and second teeth 13 alternately provided on the outer peripheral edge of a disk-shaped substrate 11 having a tool structure. As shown in the enlarged view of FIGS. 2 and 3, the first tooth 12 is formed by forming the outer edge portion of the substrate 11 into a protrusion protruding outward in a sawtooth shape, and has the same thickness as the substrate 11. , In the direction of rotation (indicated by an arrow in FIG. 1) in use, has a curved side cutting edge 14 on the front side, and has a portion 15 without a cutting edge at the tip end,
This part 15 has a relatively large front scooping angle θ2 (about 30 °)
have. The horizontal scooping angle of the horizontal cutting edge 14 is relatively large and is about 45 °. And the first tooth 12 is provided with a clam, so that FIG.
As seen in (b), the addendum side is displaced most to the side. In the figure, 16 is a bent position with a clam. Reference numeral 17 in FIG. 1 is a shaft hole.

As shown in the enlarged view of FIGS. 2 and 3, the second tooth 13 is formed by forming a protruding portion on the substrate 11 and providing a recess 18 for mounting a chip on the protruding portion. , Its recess 1
8 is brazed with a chip 19 made of cemented carbide. A lateral cutting edge 20 is formed on the chip 19, and the lateral cutting edge 20 is formed on the opposite side of the lateral cutting edge 14 of the first tooth 12 with respect to the surface of the substrate 11. The front scooping angle θ3 of the side cutting edge 20 is about 8 °, and the side scooping angle is about 5 to 8 °. Then, the tips of the first teeth 12 and the second teeth 13 project outwardly in the radial direction of the substrate 11 to the same extent. That is, the tips of the multiple first teeth 12 and the second teeth 13 are provided so as to be on one cylindrical surface 21 that is concentric with the shaft hole 17 of the substrate.

This mowing circular saw 10 is attached to the rotary shaft of a mowing machine through a shaft hole 17, and the surface of the substrate 11 on the protruding side of the first teeth 12 is directed to the ground 22 (see FIG. 3 (a)). To use. The grass on the first tooth 12 moves inward and is cut by the horizontal cutting edge 14, and the grass on the second tooth 13 is cut by the horizontal cutting edge 20. When foreign matter such as stones is present on the ground, the first teeth 1
Since 2 is biased to the ground side, the tips of the first teeth 12 come into contact with stones or the like. When the foreign matter is small, it is repelled, and when the foreign matter is large to some extent, the first tooth 12 elastically bends, and in some cases, the entire mowing circular saw 10 retracts and separates from the foreign matter, and eventually the second tooth 13 is removed. Protect. First
Since the tooth 12 is made of tool steel made of the same material as that of the substrate 11, it is hard to be chipped and keeps its protective function for a long period of time until the wear progresses considerably. Therefore, the second tooth 13 maintains the original sharpness for a long time without the chip 19 made of cemented carbide being chipped or falling off.

[0012]

According to the first aspect of the present invention, the second tooth is protected by the first tooth when the grass cutting circular saw comes into contact with a hard object on the ground side during use. Chips made of cemented carbide are prevented from chipping or falling off, and the first teeth are made of the same material as the substrate and are less likely to chip compared to chips made of cemented carbide. It has a protective effect, and therefore has the effect of maintaining good sharpness for a long period of time. The invention according to claim 2 has an effect of not giving the user a feeling of poor sharpness. The invention according to claim 3 has the effect of making the sharpness at the beginning of use extremely excellent. According to the invention described in claim 4, since the first tooth has no lateral cutting edge at its tip, the thickness of that portion is large, and therefore the wear margin is large. Therefore, the period for protecting the second tooth is long, and mowing is possible. The life of the circular saw is extended.

[Brief description of the drawings]

FIG. 1 is a partially omitted front view showing an embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

3A is a right side view corresponding to FIG. 2, and FIG. 3B is a plan view corresponding to FIG.

4A and 4B show two examples of a conventional mowing circular saw, wherein FIG. 4A is an enlarged front view of one tooth of the first example, FIG. 4B is a plan view of FIG. 4A, and FIG. An enlarged front view of one tooth of an example of
(D) is a top view of (c).

[Explanation of symbols]

 10 Mowing circular saw 11 Substrate 12 First tooth 13 Second tooth 14 Side cutting edge 15 Side without cutting edge 16 Clam bent portion 17 Shaft hole 19 Cemented carbide tip 20 Side cutting edge

Claims (4)

[Claims] 1. A disk-shaped substrate, wherein first teeth and second teeth are alternately projected along the outer edge of the disk-shaped substrate, and the first teeth are made of the same material as that of the substrate, including its blade portion. It is formed continuously on the substrate and has a crest inclined to the outside of one surface of the substrate, and the blade portion of the second tooth is formed by brazing a chip made of cemented carbide. A circular saw for cutting grass characterized by being a thing. 2. The mowing circular saw according to claim 1, wherein
A mowing circular saw, wherein the first tooth has a tip portion protruding outward in the radial direction of the base plate and a tip portion of the second tooth protruding outward in the same radial direction as the base plate. 3. The mowing circular saw according to claim 1 or 2, wherein the first tooth has a lateral cutting edge. 4. The circular saw according to claim 3,
A mowing circular saw, characterized in that the first tooth is provided with a portion where no lateral cutting edge is present at the tip thereof.