JP2745294B2 - Mowing circular saw - Google Patents

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 An earlier conventional mowing circular saw had a saw-shaped tooth formed on the outer periphery of a disk made of tool steel. That is, the cutting edge portion continued to the substrate, and was made of the tool steel of the substrate. Thereafter, since durability is required, the cutting edge portion is formed of a cemented carbide tip, and various tip shapes and brazing structures have been proposed. An example is shown in FIG. In the figure, 1 and 2 are cemented carbide chips,
3 and 4 are tool steel substrates, 5 and 6 are brazing surfaces,
θ1 is the horizontal scoop angle, which is usually about 5 to 8 °. FIG.
The mowing circular saw 7 shown in (a) and (b), and FIG.
With the mowing circular saw 8 shown in (d), while one circular saw 7 is a substantially L-shaped brazing surface 5 in the front shape,
The difference lies in that the other circular saw 8 is formed in a substantially U-shaped brazing surface 6, that is, an embedded shape in which the chip is embedded not only on one side but also on both sides. Such a mowing circular saw 8 is superior in that the brazing area of the chips can be larger than that of 7, so that the brazing strength is high and the chips are less likely to fall off. The arrow in the figure indicates the direction of rotation during use.

[0003] In general, when using a mowing circular saw, not only the grass always hits the blade but also a hard object such as a stone or a piece of metal. In such a case, a large impact force is applied to the tip. It is better that the chip is firmly fixed to the substrate. Therefore, there are many embed-type configurations, such as the mowing circular saw 8, which allow a large brazing area between the chip and the substrate. In this case, the length of the cutting edge is short. However, since the mowing circular saw is used at a high speed, the cutting amount per tooth is small, so it is considered that there is no problem.

[0004] However, the cutting edge formed by a cemented carbide tip is significantly improved in terms of durability as compared with the former cutting edge portion formed of a substrate (tool steel). However, there is a fact that it is inferior in sharpness. This is because if the lateral scooping angle θ1 is too large for the chip of the cemented carbide to be easily chipped, the durability is reduced.
The emphasis is on durability rather than a bit of poor sharpness.

[0005]

When the reason why it is said that the sharpness of a mowing circular saw using a cemented carbide tip is not always good is considered, the following can be considered. First of all, conventionally it was thought that the cutting rate per tooth was small because the mowing circular saw rotates at high speed, and the cutting edge may be short, but looking at the actual usage situation, the circular saw part is swung. However, the cut amount is not constant depending on the user or the use condition, and is not a substantially constant cutting state like a circular saw for woodwork, but rather irregular. Therefore, it is considered that the grass cut at a considerable rate in the mowing operation has entered the bottom side of the concave portion on the front side of the tooth beyond the position of the cutting edge. In such a state, the cutting is not effected by the cutting edge, and the grass is torn off while being caught on the portion of the tooth base without the cutting edge. While such a situation may occur depending on the use condition, the recent one having excellent durability has a configuration in which the brazing area is large as in the above-mentioned mowing circular saw 8, so that the length of the cutting edge is inevitably increased. It has an element that makes it shorter. For this reason, the grass that has entered inside the turning range of the cutting edge is not cut by the cutting edge, so that the sharpness is poor.

On the basis of such a concept, sharpness can be improved by increasing the length of the cutting edge in the radial direction of the substrate. However, increasing the length of the cutting edge has a problem in that the brazing area of the tip 3 is reduced as in the above-described mowing circular saw 7. In addition, since the grass cutting circular saw is used at high speed rotation, it is certain that the cutting edge used for cutting grass is mainly the tip portion of the cutting edge far from the center of rotation. Therefore, it is necessary to improve the sharpness of the tip of the cutting edge.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a chip made of cemented carbide and to use a strong brazing structure for the chip, that is, an embedded structure as it is, and to improve the sharpness of a mowing circular saw.

[0008]

According to the present invention, a plurality of recesses and protrusions are alternately formed on the outer edge of a disk-shaped substrate, and the recesses and the protrusions are embedded in the leading edge of a front edge in a predetermined rotation direction of each of the protrusions. A shape of a cemented carbide chip is brazed, a transverse cutting edge is formed on the chip, and a predetermined rotation direction of the convex portion at a position radially inward of the substrate from the position of the transverse cutting edge of the chip. In a mowing circular saw having a leading edge formed on a second horizontal cutting edge, the tip
The horizontal scooping surface of the horizontal cutting edge formed on the tape is formed in two steps,
The horizontal scoop angle of the horizontal scooping surface about the yarn surface formed on the side of the horizontal cutting edge
The horizontal scooping angle of the second horizontal scooping surface that follows is larger
It is characterized by being formed every time .

In this means, the brazing strength is high because the cemented carbide tip is embedded, but the cutting edge is short, so that the grass is used on the bottom side of the recess inside the horizontal cutting edge during use. High probability of getting into. When it enters the bottom side, it is not cut by the horizontal cutting edge of the chip, but the second horizontal cutting edge acts. Since the second horizontal cutting edge is formed of tool steel of the substrate, the second horizontal cutting edge is a material that is more easily worn than the horizontal cutting edge of a cemented carbide chip, but basically, the horizontal cutting edge of the chip mainly performs a cutting action. since, the second side cutting is blade are those ancillary considerably long term good sharpness condition is maintained because the cutting less frequently.

[0010] Also, following the horizontal scooping surface about the thread surface of the chip
Increase the horizontal scoop angle of the second horizontal scooping surface (No. 2 horizontal scooping surface)
The configuration to do, when the new horizontal scooping surface is a narrow width, but the horizontal cutting edge is a small horizontal scooping angle that is unlikely to cause chipping, and when the cross-sectional shape of the horizontal cutting edge has become rounded at the time when wear progresses to some extent, Because the width of the horizontal scooping surface is small and the horizontal scooping angle of the second horizontal scooping surface (No. 2 horizontal scooping surface) is large, the conventional horizontal scooping angle is originally small and the roundness is smaller than that of the single horizontal scooping surface. The radius becomes smaller, and the sharp state lasts longer. The horizontal scoop angle is 4
The angle is preferably in the range of ~ 8 °, more preferably 5-6 °, which is almost the same as the conventional horizontal scooping angle. When the angle is large, the sharpness is good, but the chipping of the cutting edge easily occurs,
If the width is small, chipping is unlikely to occur, but the sharpness is reduced. Therefore, it is preferable to determine the size in relation to the yarn surface width. The value is preferably small when the yarn surface width is small, and large when the yarn surface width is large. The thread surface width is preferably in the range of 0.5 to 0.8 mm, more preferably 0.6 to 0.7 mm, and if too wide, the second stage horizontal scooping surface (second horizontal salvage surface) is provided. Less meaning. The second horizontal rescue surface (No. 2 horizontal scoop)
Angle ) is 30 to 50 °, and more preferably 40 to 45 °.
゜.

The chips are protruded in the thickness direction of the substrate by the width of the yarn surface, and the second horizontal scooping surface (the second horizontal scooping surface) of the horizontal cutting edge is provided.
Surface) and the horizontal scooping surface of the second horizontal cutting edge are preferably formed on the same continuous surface. In this configuration , the second horizontal scooping surface of the horizontal cutting edge of the chip (the second horizontal scooping surface)
Surface) and the horizontal scooping surface of the second horizontal cutting edge of the substrate can be polished simultaneously.

[0012] Before Stories second side edges of the convexity of the substrate, before
Serial preferably set to those provided in the front position of the predetermined rotation direction than before SL side cutting edge formed on the chip.
According to this configuration, the thickness of the embedded portion in the front-rear direction in the rotational direction may be reduced depending on the brazing structure of the chip. Can be large. The second cutting edge is provided at the protruding portion in order to increase its size, and there is no reduction in brazing strength.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. The figure shows one of a number of teeth provided along the outer circumference of a mowing circular saw. A disk-shaped substrate 10 has a convex portion 11 and a concave portion 12 formed therein. The cemented carbide tip 14 with the U-shaped brazing surface 13
Have been brazed. In the drawing, α is a tilt angle of the chip with respect to a straight line C passing through the center of rotation of the substrate. The tip 14 has a horizontal cutting edge 15, and the horizontal cutting edge 15 has a horizontal scooping surface 16 having a horizontal scooping angle θ1 and a second horizontal scooping surface 17 having a horizontal scooping angle θ2. Have. The horizontal scoop angle θ1 is an angle (4 to 8 °) at which chipping is unlikely to occur as in a normal mowing saw blade, and the horizontal scoop angle θ
2 is substantially larger (30 to 50 degrees) than θ1. 1B, the thickness T of the chip 14 is slightly larger than the thickness t of the substrate 10, and at least the small dimension T1 (0.5
〜0.8 mm). The scooping surface 16 is formed with a width corresponding to the small dimension T1.

At the time of use of the convex portion 11 of the substrate 10 in the rotation direction front edge, a second horizontal cutting edge 18 having an angle θ2 is attached to the horizontal cutting edge 1.
5 is provided so as to be substantially continuous. This second horizontal cutting edge 1
8 is a horizontal scooping surface 19 which is an extension of the second horizontal scooping surface 17
Is formed.

A second embodiment of the present invention will be described with reference to FIG. This second embodiment also shows one of a large number of teeth provided along the outer circumference of the mowing circular saw, and the disk-shaped substrate 20
Are formed with a convex portion 21 and a concave portion 22, and a cemented carbide chip 24 is brazed to the convex portion 21 with a brazing surface 23 similar to a conventional special embedded type. The first embodiment differs from the first embodiment in that a brazing structure for the tip 24 and a second lateral cutting edge 28 are provided.
Is mainly located slightly in front of the horizontal cutting edge 25 in the rotation direction, and the other points are almost the same, so that the description is omitted. 26 is the horizontal scooping surface of the chip, 27 is the second horizontal scooping surface, 28 is the second horizontal cutting edge, 29 is the horizontal scooping surface of the second horizontal cutting edge, θ1 is the same horizontal scooping angle as in the first embodiment, and θ2 is also the same. The angle is the same as in the first embodiment, and the horizontal scooping surfaces 27 and 29 are not continuous.

A third embodiment of the present invention will be described with reference to FIG. The third embodiment also shows one of a large number of teeth provided along the outer circumference of the mowing circular saw, and the disk-shaped substrate 30
Are formed with a convex portion 31 and a concave portion 32, and the convex portion 31 has a similar embedding type brazing surface 33, which is different from that of the first embodiment in the mounting angle of the chip and the way of providing the horizontal cutting edge to the chip. Is used to braze the cemented carbide tip 34. The second embodiment is different from the first embodiment mainly in that the position of the second lateral cutting edge 38 of the tip 34 is located slightly ahead of the lateral cutting edge 35 in the rotation direction, and the other parts are almost the same, so that the description is omitted. . 36 is the horizontal scooping surface of the chips,
37 is the second horizontal scooping surface, 38 is the second horizontal cutting edge, 39 is the second
The horizontal scooping surfaces of the horizontal cutting edges, θ1 and θ2, have the same angle as in the first embodiment, and the horizontal scooping surfaces 37 and 39 are not continuous.

In the above-mentioned first, second and third embodiments, the mowing circular saw mainly uses the chips 14, 24, 3
The cutting edges 15, 25 and 35 of No. 4 perform the cutting action, and the grass that has entered the center side beyond the horizontal cutting edges 15, 25 and 35 for some reason is cut by the second horizontal cutting edges 18, 28 and 38. The horizontal cutting edges 15, 25, and 35 of the chips have a horizontal scooping angle θ1 at which the normal chipping is unlikely to occur, and as the wear progresses, the cutting edge cross-sectional shape becomes rounded. It is smaller than the conventional one in which the surface 17 is not provided, and the cutting action is less reduced. Therefore, the chips 14, 24, and 34 have a strong brazing structure, the sharpness is hardly reduced even with the progress of wear, and the horizontal cutting edges are substantially formed by forming the second horizontal cutting edges 18, 28, and 38. Is formed so as to extend inward in the radial direction, and there is little winding of the grass or uncut leaves, and durability is good. In the first embodiment, the horizontal scooping surfaces 16 and 18 are used.
Are continuous, so that they can be polished at the same time, and there is an advantage that manufacture is easy.

[0018]

In the first embodiment, θ1 is 5 °, θ2 is 45 °, t is 1.2 mm, T is 2.0 mm, and T1 is 0.2 mm.
5 mm.

[0019]

According to the first aspect of the present invention, the conventional chip-type embedded structure having a high brazing strength of the chip is left as it is, and the second cutting edge performs a cutting action to improve sharpness. To play . Also crossing the tip
The long-lasting blade sharpens the overall sharpness
I do. The second aspect of the present invention is directed to the second aspect of the lateral cutting edge of the insert.
Since the No. 1 horizontal scooping surface and the horizontal scooping surface of the second horizontal cutting edge of the substrate are formed on the same continuous surface, it can be polished at the same time. According to the third aspect of the present invention, the size of the substrate in front of the embedded portion of the chip in the front-rear direction can be made sufficiently large, and the mounting strength of the chip can be secured.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, wherein (a) is an enlarged front view of one tooth and (b) is a plan view of (a).

2A and 2B show a second embodiment of the present invention, wherein FIG. 2A is an enlarged front view of one tooth, FIG. 2B is a view as viewed from the arrow B of FIG. 2A, and FIG. 2C is AA of FIG. It is sectional drawing.

3A and 3B show a third embodiment of the present invention, wherein FIG. 3A is an enlarged front view of one tooth, FIG. 3B is a view as viewed from an arrow E in FIG. 3A, and FIG. 3C is DD in FIG. It is sectional drawing.

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 plan view of (c).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 11 Convex part 12 Concavity 13 Brazing surface 14 Chip 15 Horizontal cutting edge 16 Horizontal scooping surface 17 No. 2 horizontal scooping surface 18 Second horizontal cutting edge 19 Second horizontal scooping surface 20 Substrate 21 Convex portion 22 Depressed portion 23 Brazing surface 24 Chip 25 Horizontal cutting edge 26 Horizontal scooping surface 27 No. 2 horizontal scooping surface 28 Second horizontal cutting edge 29 Second horizontal scooping surface 30 Substrate 31 Convex part 32 Concave 33 Brazing surface 34 Chip 35 Horizontal cutting edge 36 Horizontal scooping surface 37 No. 2 horizontal scooping surface 38 2nd horizontal cutting edge 39 2nd horizontal scooping surface

Claims (3)

(57) [Claims] 1. A plurality of recesses and protrusions are alternately formed on the outer edge of a disk-shaped substrate, and an embedded cemented carbide chip is brazed at a tip of a front edge in a predetermined rotation direction of each of the protrusions. Then, a lateral cutting edge is formed on the tip, and the lateral cutting edge of the tip is
A mowing circle in which a front edge portion in the predetermined rotation direction of the projection at a position radially inward of the substrate from the position is formed on a second lateral cutting edge.
In a saw, a horizontal scoop of a horizontal cutting edge formed on the tip
The surface is formed in two stages, about the yarn surface formed on the side of the horizontal cutting edge
From the horizontal scooping angle of the horizontal scooping surface, follow the second stage horizontal scooping surface
A mowing circular saw characterized in that a horizontal scooping angle is formed at a large angle . 2. The mowing circular saw according to claim 1, wherein
The chip is projected in the thickness direction of the substrate in a dimension equivalent to the yarn face width.
And the second stage horizontal scooping surface formed on the chip,
The horizontal scooping surface of the second horizontal cutting edge at the projection of the substrate is continuous.
A mowing circular saw characterized by being formed on the same plane . 3. The mowing circular saw according to claim 1, wherein
The second lateral cutting edge at the convex portion of the substrate is formed on the chip.
A front side position in the predetermined rotation direction with respect to the formed horizontal cutting edge.
Mowing circular saw, characterized in that it is provided at a location.