JPH0137380Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a circular saw for mowing grass in which a cemented carbide cutting edge tip is joined to the saw teeth formed on the peripheral edge of a disc-shaped steel saw body.

BACKGROUND ART Conventionally, circular saws for mowing grass have been used in which saw teeth are formed on the peripheral edge of a disc-shaped steel saw body. However, steel saw teeth have low wear resistance and wear out quickly, resulting in an extremely short service life. For this reason, circular saws have come to be used in which one cemented carbide cutting edge tip is bonded to each saw tooth formed on the peripheral edge of a steel saw body. However, because conventional cemented carbide cutting tips protrude outward in the radial direction from the serrations, they are prone to colliding with stones, etc. Moreover, cemented carbide tips are hard and have high wear resistance, but are brittle, so they do not collide with stones, etc. It had the disadvantage that it easily chipped when it was used, so it could not be used in places with stones.

The purpose of this invention is to solve the above-mentioned problems and to provide a circular saw for cutting grass that has a cemented carbide cutting edge chip that is hard to chip and has a long life.

Means for Solving the Problems The circular saw for mowing according to this invention is a circular saw for mowing in which a cutting edge tip made of cemented carbide is joined to the saw teeth formed on the periphery of a disc-shaped steel saw body. , the serrations on the rear side of the cutting tip protrude outward from the cutting tip.

In this specification, front, rear, left, and right refer to the moving direction of the cutting edge tip during cutting, and the outside refers to the outside in the radial direction of the saw body.

Example Fig. 1 shows a part of a circular saw for mowing grass.
A cutting edge tip 12 made of cemented carbide is attached to each of a plurality of saw teeth 11 formed on the peripheral edge of a disk-shaped saw body 10 made of hardened steel. Details of the chip 12 are shown in FIG. 2, and details of the mounting portion of the chip 12 are shown in FIGS. 3 and 4.

One tip mounting groove 13 is formed in the front part of each saw tooth 11 of the saw body 10.
The front side and the rear side thereof form protrusions 14 and 15 that protrude outward, respectively. Front and rear protrusions 14,
The opposing edges of the grooves 15 are straight lines parallel to each other, and therefore the front and rear widths of the grooves 13 are constant. The bottom edge 16 of the groove 13 is in the shape of a straight line orthogonal to the opposing edges of the front and rear protrusions 14 and 15. The height of the front protrusion 14 is lower than the height of the tip 12, and the front part of the tip 12 protrudes outward from the protrusion 14. The height of the protrusion 15 on the rear side is higher than the height of the tip 12, and this protrusion 15 protrudes outward from the tip 12.

The chip 12 has a columnar shape with a substantially rectangular cross section. The front surface 17 of the chip 12 has a cylindrical surface that is most concave at the center in the left-right direction, and a shallow chip positioning groove 19 is formed at the center in the left-right direction of the portion excluding the upper part of this surface 17, making a right angle to the bottom surface 18. The height of this groove 19 is equal to the height of the protrusion 1 on the front side of the sawtooth 11.
The height is approximately equal to the height of the trailing edge of No. 4. A shallow chip positioning groove 21 that is perpendicular to the bottom surface 18 and extends over the entire height is formed in the center of the rear surface 20 of the chip 12 in the left-right direction. The horizontal widths of these grooves 19 and 21 are slightly larger than the thickness of the saw body 10, and the longitudinal width of the tip 12 at the grooves 19 and 21 is slightly smaller than the longitudinal width of the tip mounting groove 13.

Chip 12 has front and rear grooves 19 and 21 with serrations 1
1, and at least one, preferably both, of the upper end portions of the bottom surface 18 and the front groove 19 are fitted with the opposite edges of the front and rear protrusions 14 and 15 of the chip mounting groove 13 and the front protrusion. 1
The chip is inserted into the chip mounting groove 13 so as to be in contact with the corresponding part on the upper end of the rear edge of the sawtooth 1 by brazing.
1. At this time, the front and rear grooves 19 and 21 of the chip 12 fit with the opposing edges of the front and rear protrusions 14 and 15, whereby the chip 12 is positioned in the front and rear direction and the left and right direction, and the bottom surface 18 and the front side of the chip 12 are positioned. The tip 12 is positioned in the vertical direction by having at least one of the upper end portions of the groove 19 contact a corresponding portion of the tip attachment groove 13. For this reason, the chip mounting groove 1
The chip 12 is positioned and fixed simply by inserting it into the chip 3 from the outside, and the mounting accuracy is very high. Therefore, there is no need for a special jig to fix the chip in place during brazing as in the past, and brazing is easy, and the user can easily replace the chip 12. be able to. Further, since the mounting precision of the chip 12 is very high, it is only necessary to attach the chip 12, which has been ground to a predetermined size in advance, to the sawtooth 11.

When mowing the grass using the circular saw, initially, the grass is mainly cut at the rear protrusion 15 that protrudes outward from the tip 12. At this time,
Since the tip 12 is located inside the protrusion 15 on the rear side, there is very little risk of it colliding with stones, etc.
Therefore, there is very little risk of chipping. The protrusion 15 on the rear side of the sawtooth 11 may collide with a stone or the like, but since steel has high toughness, it will not chip. As the mowing progresses, the rear protrusion 15 wears out, as shown in FIG. 5, and eventually the grass also comes to be mowed at the tip 12. Then, as shown in FIG. 6, the tip 12 also gradually wears out, but since cemented carbide is hard and has high wear resistance, the progress of wear from now on is extremely slow. In addition, even in such a state, since the protruding portion 15 on the rear side protrudes outward from the tip 12, the tip 12
There is very little risk of it chipping due to collision with stones etc. Therefore, the lifespan of the circular saw is very long.

The amount of protrusion of the protrusion 15 on the rear side of the tip 12 is determined in consideration of the chip 12's resistance to chipping, sharpness, wear of the protrusion 15, and the like. If the amount of protrusion is small, there is a risk that the tip 12 will be chipped, and if it is large, the cutting quality will be poor and the abrasion of the protrusion 15 itself will be increased. By appropriately selecting the amount of protrusion of the protruding portion 15 on the rear side of the tip 12, it is possible to change the conventional circular saw, which only has saw teeth formed on the peripheral edge of the steel circular saw body, and the cemented carbide cutting edge tip into a saw tooth. Experiments have shown that the above-mentioned circular saw has a much longer service life than a conventional circular saw that is mounted so as to protrude further outward.

When the tip 12 and the rear protrusion 15 are so worn that mowing becomes difficult, the worn tip 12 is removed from the saw blade 11, and the rear protrusion 15 is shaped as shown in FIG. Then, install a new chip 12 in the chip installation groove 13. At this time, a tip 12 shorter than the original tip 12 is prepared in advance so that the rear protrusion 15 protrudes outward from the tip 12 by an appropriate amount, and this tip is attached to the sawtooth.
It is preferable to attach it to 1.

Configuration of sawtooth 11 and tip 12, tip 12
The mounting method is not limited to that of the above embodiment, and can be changed as appropriate.

8 to 12 show other embodiments of this invention, and the same parts as in the above embodiment are given the same reference numerals. In the case of FIGS. 8 to 11, the tip 12 is not provided with a positioning groove, and the desired surface of the tip 12 is brazed to the corresponding edge of the sawtooth 11. In the case of FIG. 12, a positioning groove 21 is provided only on the rear surface 20 of the chip 12, and this groove 21 fits into the front edge of the protrusion 15.

Effects of the invention According to the circular saw for mowing of this invention, in the circular saw for mowing, the blade tip 12 made of cemented carbide is joined to the saw teeth 11 formed on the peripheral edge of the disc-shaped steel saw body 10. Since the serrations 11 on the rear side of the cutting edge tip 12 protrude outward from the cutting edge tip 12, there is extremely little risk of the tip colliding with a stone or the like and chipping, and since the cutting edge tip is made of cemented carbide, it The lifespan is much longer than that of Therefore, it can be used for a long time even in places with stones.

[Brief explanation of the drawing]

Figures 1 to 7 show one embodiment of this invention,
Fig. 1 is a side view showing a part of a circular saw for mowing, Fig. 2 is a perspective view of the cutting edge tip in Fig. 1, Fig. 3 is an enlarged view taken along line X-X in Fig. 1, Fig. 4 is a sectional view taken along the Y-Y line in Figure 3, Figures 5 to 7 are equivalent to Figure 4, which sequentially show the progress of wear during mowing, and Figures a and b in Figures 8 to 12 are 4 is a drawing corresponding to FIG. 4 showing five embodiments different from those described above, and a drawing showing this from the outside. DESCRIPTION OF SYMBOLS 10...Saw body, 11...Saw blade, 12...Blade tip, 15...Protrusion part.

Claims (1)

[Scope of Claim for Utility Model Registration] A circular saw for grass cutting in which a cemented carbide cutting edge tip 12 is joined to saw teeth 11 formed on the peripheral edge of a disc-shaped steel saw body 10, after the cutting edge tip 12. This circular saw for mowing grass is characterized in that a side sawtooth 11 protrudes outward from a cutting edge tip 12.