JP2010142198A - Circular saw for mowing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the blade of a circular saw for mowing, long in service life and having fairly good sharpness as well. <P>SOLUTION: The circular saw for mowing is provided, having a chip of cemented carbide each provided with a number of blades on the outer rim of a disc-shaped base plate. The saw forms the following profiles: a scoop plane 7 with a positive scooping angle θ3, a plane made by moving such a part that a plane on the front side of rotating direction of the blades 3 turns from the outer rim toward the inside while a straight line kept parallel to the central axis of the rotation as it is; an escape plane 8 with an escape angle θ2, a plane made by moving a plane behind the rotating direction of the blades toward the inside in the rear while a straight line makes an angle with the central axis of the rotation; and a chip 4 of a flank profile corresponding to that of a recessed part in the recessed part 12 opened on the face on the front side of the blades and formed inside off the outer rim through penetrating in the thickness direction of the base, wherein the chip has an insidely enlarged part 13 formed in such a way that the recessed part turns from the rim of the central axis side of the rotation toward the depth and recessed on the central axis side of the rotation behind the rotating direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a grass cutting circular saw that is attached to a brush cutter and used for grass cutting.

There exists a thing of the cited reference 1 in this kind of conventional. This is a grass cutter blade for a brush cutter, which is formed in a disc shape and has a plurality of cutting blades at the peripheral end portion thereof, and a blade portion is provided at a valley portion between the cutting blades, and at the tip portion of the cutting blade, This is a configuration in which a cemented carbide tip blade having the same thickness as the thickness of the mowing blade main body is embedded following the outer periphery of the cutting blade and the blade portion of the valley portion. That is, the blades are continuously provided in the valleys between the cutting blades, the front portion of the cutting blade, and the carbide tip embedded in the tip portion included in the cutting blade front portion. A series of blades are formed in a bowl shape by a surface on one side in the traveling direction of the cutting blade and a side surface, and the blade forms an acute angle by the side surface.
JP-A-9-35

  In the conventional grass cutting circular saw, two surfaces of the blade portion forming the blade are formed at an acute angle. Generally, the smaller the angle is, the better the sharpness is, but the blade life is shortened. Conversely, the larger the angle is, the worse the sharpness is, but the longer the life is, so 45 to 60 degrees is adopted. Seems to be. This way of thinking is the sense of cutting things with a blade. However, it may be extreme in the field where the mowing circular saw is actually used, but it may be used even if the blade of the blade part is worn so that it is hardly recognized as a blade. Although the sharpness is poor, it is recognized that the mowing work has been done somehow.

  For this reason, we will not provide a sense of cutting grass with a blade like a sickle, but will provide a blade of a grass cutting saw that has a long life and a very good sharpness from a different perspective. It is what.

  The means of the present invention is a grass cutting circular saw in which a large number of blade portions are formed on the outer edge of a disk-shaped substrate and each of the blade portions is provided with a cemented carbide chip. The surface of the blade portion is a surface formed by moving a portion inward from the outer edge while maintaining a straight line parallel to the central axis of rotation, and a scooping surface having a positive scooping angle, The surface on the rear side in the rotational direction is a surface formed by moving a straight line that forms an angle with the central axis to the rearward inner side and a clearance surface having a clearance angle, and is open on the front surface of the blade portion and the substrate The chip having a side surface shape corresponding to the side surface shape of the concave portion is provided in a concave portion penetrating in the thickness direction and formed on the inner side of the outer edge end, and the concave portion is provided on the central axis side of the opening. Center axis side behind rotation direction from edge to back Characterized in that it has an inner enlarged portion formed by recessed.

  The grass cutting circular saw by this means is formed in the shape of the top of a triangular pyramid with the outer end of the blade portion formed by a scooping surface and a flank and a side surface or by a scooping surface and two flank surfaces distributed on both sides. It becomes a virtual cutting edge. Although this cutting edge is point-like, it is considered that it is easily worn, but when the tip is in a slightly rounded state, the sharpness has not been reduced so much and this state continues for a long time. This is considered because it has a scooping surface along the rotation center axis. In other words, both sides of the scooping surface are involved in the cutting to the same extent, wear is roughly distributed, and the scuffing surface is worn out more than the one in which the scooping surface is tilted with respect to the center axis of rotation and only one side of the scooping surface is involved in cutting. It is difficult. And when abrasion progresses to some extent, sharpness is restored by re-polishing only the flank. When this re-polishing is repeated several times, the tip portion forms the outer end of the blade portion which was initially formed of the substrate metal. When the tip of the blade portion is formed at the tip portion, since the wear resistance is high, the life until the next re-polishing is extended.

  In the above means, it is preferable that the chip is provided so as to protrude from both sides of the substrate. In this configuration, in general, the chip is brazed to the substrate, and the substrate side surface and the chip side surface are polished at the same time as the substrate side surface, but the chip side surface protrudes slightly from the substrate side surface. Compared with the one that protrudes a little, the brazing strength is higher, that is, the possibility of the chip falling off is lower.

  In the above means, the tip has a configuration in which the outer end of the blade portion is formed in the top of a triangular pyramid by a scooping surface, a flank surface, and one side surface, and the apex is a practical cutting blade. good.

  In the above means, the chip may be formed in a triangular pyramid top shape by a scooping surface and two flank surfaces distributed on both sides, and its apex may be a practical cutting edge.

  In the above-mentioned means, it is preferable to have a blade portion that is regenerated by re-polishing the flank. According to this configuration, since the blade portion is regenerated by re-polishing only the flank, the re-polishing operation is easy, and the re-polishing cost can be reduced.

In the inventions of claim 1, claim 3, and claim 4, since the pointed apex of the blade portion is difficult to wear, the life until re-polishing is increased correspondingly, and when the degree of wear progresses, The sharpness is restored by re-polishing only the flank, so that the effect of easy re-polishing is achieved.
According to the second aspect of the present invention, since the brazing strength is high, the tip is difficult to drop off and the cutting edge is hardly chipped.
The invention according to claim 4 has an effect of reducing the re-polishing cost.

  In a grass cutting circular saw in which a large number of blade portions are formed on the outer edge of a disk-shaped substrate and each blade portion is provided with a cemented carbide chip, the surface on the front side in the rotation direction of the blade portion when used for mowing is from the outer edge. The inner part is formed as a scooping surface having a positive scooping angle formed by moving a straight line parallel to the center axis of rotation while maintaining its parallel state, and on the rear side in the rotational direction of the blade portion. The surface is a surface formed by moving a straight line that forms an angle with the central axis rearward and inward, and is formed as a clearance surface having a clearance angle, and opens in the front surface of the blade portion and penetrates in the thickness direction of the substrate Then, the tip having a side surface shape corresponding to the side surface shape of the recess is brazed in the recess formed inside the outer edge end, and the recess is an edge of the opening on the central axis side. Recessed from the center axis to the back in the direction of rotation Has an inner enlarged portion formed Te, the chip is slightly protruded from the substrate surface each other, using those slightly larger thickness dimension than the thickness of the substrate.

An embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the mowing circular saw 1 is provided with a plurality of blade portions 3 on a disk-shaped substrate 2 and a cemented carbide chip 4 on the blade portion 3.
The substrate 2 is made of a tool steel plate, has a shaft hole 5 for attachment to the rotary shaft of the mower, and has similar blade portions 3 arranged at equal intervals on the outer peripheral portion. An appropriate number of through-holes 6 are punched between the shaft hole 5 and the shaft hole 5 in consideration of weight reduction and design.

As shown in FIG. 3, the blade portion 3 has a scooping surface 7 on the front side in the rotation direction (direction indicated by an arrow A in the figure) when the mowing circular saw 1 is used, and a flank 8 on the rear side. It has a trailing edge 9.
The scooping surface 7 is formed by a surface formed by linearly moving a straight line parallel to the rotation center axis line from the blade edge 10 to the center side of the substrate 2 while maintaining the parallel state. The scooping surface 7 has a line that coincides with the radius line r with respect to the radius line r connecting the blade edge 10 and the center of the shaft hole 5 in the front view (see FIG. 3A). The hole 5 side is formed on a surface represented by a line inclined to the rear side by an angle θ1 (15 °). That is, this angle θ1 is a positive crawl angle. The scooping angle θ1 can generally be selected from about 3 ° to 20 °, preferably 6 ° to 18 °. The edge of the substrate 2 continues to the front end at the inner end of the scooping surface 7 and curves to form a trough 11 between the blade portions, and continues to the rear edge 9 of the front blade portion 3. . The outermost end of the blade portion 3 is a blade edge 10 in the figure, which is the apex of the apex of a triangular pyramid composed of the back surface, the rescue surface, and the relief surface of the substrate 2.

  The flank 8 is formed by a surface continuing from the blade edge 10 to the rear side in the rotational direction, and the rear surface in the rotational direction (direction indicated by the arrow A) of the blade portion 3 shown in FIG. ) Of the straight line x2 that forms an angle α with the straight line x1 that is parallel to the central axis line, that is, the front side of the blade portion 3 (see FIG. 5B) (see FIG. 5B), the line x1 (to the central axis line) A straight line x2 obtained by inclining an angle α (45 °) downward to the right is formed so as to move backward so as to descend at an angle θ2 (10 °).

  As shown in FIG. 3 (a), the cemented carbide chip 4 has a rectangular shape with a front end formed in an arc shape and a uniform thickness with a thickness slightly larger than the thickness of the substrate 2. The concave portion 12 is formed and fitted into the substrate 2 so as to constitute most of the scooping surface 7 and is brazed so as to protrude from the front surface and the back surface of the substrate 2 by the same size. As shown in the figure, the recess 12 is opened from a slightly inner side (the central axis side of the shaft hole 5) to the lower end of the rescue surface 7 and penetrates in the thickness direction of the substrate 2. The inner enlarged portion 13 is extended so that the edge on the central axis side is recessed toward the central axis side on the rear side in the rotation direction. The front shape of the chip 4 corresponds to the front shape of the recess 12.

This mowing circular saw 1 is attached to the rotary shaft of a mowing machine and used for mowing as in the prior art. In the state of the blade portion 3 that is worn by use, the blade edge 10 is rounded and the roundness gradually increases. And the sharpness gradually decreases. Initially, the cutting edge is part of tool steel, so it wears quickly, but compared to the one made of conventional tool steel, the one in the above example has a longer working time until the sharpness is reduced to the same extent. Are better. Further, even after the most polishing is repeated, the cutting edge 10 becomes the cemented carbide tip 4, until the sharpness is reduced to the same degree while the sharpness is almost the same as that of the conventional cemented carbide blade. Excellent in terms of long working hours.
Further, the mowing circular saw 1 performs only the flank 8 so as to have the original clearance angle 8 before wear when re-polishing. As a result, the blade edge 10 is regenerated. Therefore, the re-polishing operation is easy. Further, since the cemented carbide chip 4 is fitted and brazed to the recess 12 having the inner enlarged portion 13, the holding strength of the chip is high, the dropout during use is extremely small, and the durability is high.

  Moreover, in the practical test conducted in order to examine the appropriate re-polishing time of this grass cutting circular saw 1, how much the user has worn out when he / she thinks that re-polishing is necessary in terms of sharpness. When we examined whether there was any problem, that is, when we decided to re-grind only by sharpness without considering the observation of the cutting edge at all, even though the sharpness was reduced to some extent from the beginning, it was not re-polished yet It continued to be okay, and until chip 4 was shortened to a third to a quarter. From these results, users who prefer to have a very good sharpness should use it while performing the most suitable polishing, and users who can ignore a certain degree of sharpness will need to be re-polished from the new state to the end. You can use it without using it. That is, the mowing circular saw 1 need not be polished at all in some cases.

As another embodiment, a modified example of the blade portion that can obtain substantially the same effect as the above embodiment will be described with reference to FIGS.
4 (a) to 4 (d) show the blade portion 3a of the modified example 1, in which the tip 4a is formed longer than the tip 4 of the initial blade portion 3 of the above embodiment, and the substrate tool The state in which the cutting edge 10 is formed of steel can be continuously repeated for a long time.
FIG. 4 (e) shows a blade portion 3b which is one of the two types of blade portions 3a and 3b of the modified example 2. In the modified example 1, all the blade portions 3a of the entire circumference are viewed from the front side in the rotational direction (FIG. 4 (b)) shows a blade portion 3b which is the same flank 8a inclined downward to the right, but a flank 8b inclined downward to the opposite left, and in Modification 2, the blade portions 3a and 3b are shown. Are arranged alternately.
FIG. 5 (a) shows a blade portion 3c of Modification 3, and its flank 8c is inclined downward at an angle α (45 °) from the middle blade edge 10c between the front and back surfaces to both sides.
FIGS. 5B to 5G show different blade portions 3d to 3i of the modified examples 4 to 9, respectively, and the shapes and the like of the tips 4d to 4i and the rescue surfaces 7d to 7i are different. In both cases, the chip protrudes slightly on the front and back sides of the substrate, and the same is that the inner enlarged portion 13 is provided in the recess 12.

It is a front view of one Example of this invention. It is a rear view of the same embodiment (A) is a front view, (b) is a left side view, (c) is a plan view, and (d) is a rear view. It is a blade part enlarged view which shows the modification 1 of a blade part as another Example of this invention, (a) is a front view, (b) is a left view, (c) is a top view, (d) is a back surface FIG. (E) is a left side view of one blade part of two types of blade parts of Modification 2. The other modification 3-9 of a blade part of this invention is shown, (a) is a left view of the modification 3, (b), (c), (d), (e), (f), ( g) is a front view of each of Modifications 4 to 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mowing circular saw 2 Board | substrate 3 Blade | tip part 4 Tip 5 Shaft hole 6 Through-hole 7 Scoop surface 8 Relief surface 9 Trailing edge 10 Cutting edge 11 Valley part 12 Recessed part 13 Inner expansion part θ1 Relief angle θ2 Relief angle x2 Straight line x2 Straight line α Angle

Claims (5)

In a grass cutting circular saw in which a large number of blade portions are formed on the outer edge of a disk-shaped substrate and each blade portion is provided with a cemented carbide chip, the surface on the front side in the rotation direction of the blade portion when used for mowing is from the outer edge. The inner part is formed as a scooping surface having a positive scooping angle formed by moving a straight line parallel to the center axis of rotation while maintaining its parallel state, and on the rear side in the rotational direction of the blade portion. The surface is a surface formed by moving a straight line that forms an angle with the central axis rearward and inward, and is formed as a clearance surface having a clearance angle, and opens in the front surface of the blade portion and penetrates in the thickness direction of the substrate The chip having a side surface shape corresponding to the side surface shape of the recess is provided in the recess formed on the inner side of the outer edge, and the recess extends from the edge on the central axis side of the opening to the back. It is formed to be recessed into the central axis side at the rear in the direction of rotation Mowing circular saw, characterized in that it comprises an inner enlarged portion. 2. The mowing circular saw according to claim 1, wherein the chip is provided so as to protrude from both sides of the substrate. 3. The mowing circular saw according to claim 1 or 2, wherein the tip of the tip is formed in the shape of a triangular pyramid by a scooping surface, a flank surface and one side surface of the blade portion, and the apex of the tip is the fact. The mowing circular saw that is the upper cutting edge. 3. The mowing circular saw according to claim 1 or 2, wherein the tip is formed in the top of a triangular pyramid by a scooping surface and two flank surfaces distributed on both sides, the apex of which is a virtual cutting edge. Become a mowing circular saw. The mowing circular saw according to claim 1, 2, 3, or 4, further comprising a blade portion regenerated by re-polishing the flank.

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