JP2012125181A - Saw blade for mowing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a saw blade for mowing which is configured to be hardly damaged when making contact with a foreign substance such as a stone during mowing, and to prevent a user's hands from being wounded with a cutting edge of the saw blade in handling the saw blade.SOLUTION: The saw blade 1 for mowing includes a number of teeth 4 facing forward in the direction of rotation on a peripheral edge of a disk-shaped base 2. A scooped face 7 of each tooth extends toward the center of the base, and a flank face 8 of the tooth extends rearward while displaced inward from a cutting edge circle 14 passing through a cutting edge 5 of the tooth. In the saw blade 1, an extension part 11 of the flank face 8 of the tooth turns outward on the way to project further than the cutting edge circle to form a projection 12. A rear edge 15 in the direction of rotation of the projection turns toward the center of the base from a projecting end, extends in such a state as to face an extension part of the scooped face of the next tooth, and after that, and continues to the extension part 18 of the scooped face 7 of the next tooth, forming a curved part 17 which is recessed outward. The front edge in the direction of rotation of the projection is formed as a curved surface projecting outward diagonally in the front from the flank face toward the projection end. A side face of the projection end of the projection is formed in a small arc shape or light-chamfered shape.

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a saw blade for mowing of a mower (mower) with a manually operated prime mover used for grass mowing.

  Conventional saw blades for mowing generally have a circular saw shape, and previously, the outer periphery of a disk-shaped metal plate was formed in a saw blade shape. Recently, most saw blades for mowing are provided with a blade formed of a chip made of cemented carbide having high wear resistance on the outer periphery of a disk-shaped base metal. The thing of patent document 1 equips the outer peripheral part of a disk-shaped cutter with several blades, and the outer peripheral part of the cutter is radially outward from the rotational trajectory of the cutting edge of the cutting blade behind the cutting blade in the rotational direction. It is the structure which provided the convex part which protrudes. With this configuration, the convex part comes in contact with an obstacle such as a stone before the cutting edge of the cutting blade, so that the presence of the obstacle can be detected and sensed, and the operator can control the cutter to control the cutting edge. It is possible to prevent contact with obstacles. In addition, the one described in Patent Document 2 is provided with a blade base protruding radially outward and a concave portion recessed radially inward in the outer circumferential portion of the disk-shaped base metal, and alternately provided in the circumferential direction. A blade is provided on the rotating surface side, and the radial position of the bottom surface of each recess is made substantially the same as the radial position of the base end of each blade. With this configuration, the object to be cut fitted in the recess directly collides with the blade on the subsequent side, so that it is cut smoothly and does not get entangled with the blade.

JP 10-229721 A JP 2006-288268 A

  Conventional saw blades for mowing contact with stone or concrete during use cause premature wear, chipping, and chipping off, and there is a problem that the lifespan is short depending on how to use. Further, in handling the saw blade for mowing, there is also a problem that it is easy to cut the hand with the blade edge, for example, when attaching or removing. The present invention uses the saw blade for mowing to ensure that the blade portion is not easily damaged when the saw blade comes into contact with foreign matter such as pebbles, pieces of wood, concrete or large stones when mowing, ensuring good sharpness. The problem is to make the life longer than before and to eliminate hand injury due to the cutting edge in handling.

  The saw blade for mowing of the present invention has a large number of blade portions facing forward in a predetermined rotational direction at the peripheral portion of the disc-shaped base metal. The blade portion is moved rearward in the rotational direction while being displaced so that the scooping surface of the blade extends toward the center of the base metal and the flank surface is gradually separated inward from the blade edge circle passing through the blade edges of the multiple blade portions. It is distracted. The extended part of the flank of the blade is provided with a convex part that protrudes outward from the middle and protrudes beyond the cutting edge circle, and the trailing edge in the rotational direction of the convex part continues from the protruding end part toward the center of the base metal After extending in a state of facing the extending portion of the next scooping surface of the next blade, an outwardly concave curved portion is formed and connected to the extending portion of the scooping surface of the next blade.

  This mowing saw blade is attached to a normal mowing machine and used in the same manner as before, and the mowing operation is the same as before. When the mowing operation is performed, the convex portion hits the grass, the grass is bounced so as to be pushed away, and once leaves the saw blade side, but returns to the original by the reaction and is pressed against the saw blade side. As a result, the grass enters the recessed portion between the convex portion and the blade portion, that is, even if the convex portion exists, the front portion of the blade portion is good, and the grass that has entered is cut away by the blade. Become. In addition, when there is a foreign object such as a small stone or a hard wooden piece, the tip of the convex portion that forms the maximum outer diameter portion and is on the front side of the blade hits the foreign object, so that the foreign object is bounced off. Therefore, the foreign object does not directly hit the blade, and the blade is reliably protected. Also, when cutting concrete grass, concrete gutter blocks, or grass near curbstones, a saw blade may hit the concrete or stone. Also in this case, the convex portion hits and the saw blade side is repelled, and the blade does not directly hit the concrete fence, the concrete side groove block, or the curb. Thus, since the damage of the blade is prevented by the presence of the convex portion, the sharpness of the state in which the blade continues to mow only the grass is maintained until the convex portion is worn and cannot protect the blade.

  The front edge in the rotation direction of the convex portion may be formed as a curved surface that protrudes outward obliquely forward from the flank face toward the protruding end portion (Claim 2). The reaction force is small because it is in a sliding state rather than a biting state as when the blade edge directly hits when a foreign object hits it. In particular, when the foreign matter is a fence net (made of wire), it does not get into a state of being wound like a conventional blade by hitting the convex portion, so that it is not seriously damaged. In addition, the front surface in the rotation direction of the convex portion is worn by hitting grass or foreign matter when mowing, but this configuration can increase the wear margin and increase the life of the convex portion because it is a curved surface that protrudes diagonally forward. Since the period during which the blade is protected by the convex portion becomes longer, the life of the saw blade for mowing is also extended. Further, the mowing saw blade can be returned to a state close to a new one by re-polishing before the protruding end circle of the convex portion becomes smaller than the cutting edge circle.

  The blade portion may be formed of a cemented carbide chip and brazed to a base metal (Claim 3). Most of the cutting parts of recent saw cutting blades are made of cemented carbide chips and brazed to a base metal (usually made of steel plate of tool steel). This configuration can be applied to extend the life of the blade formed by the tip. In particular, a blade formed of a chip made of cemented carbide has high wear resistance when cutting only grass, but it is easily chipped and weak against contact with foreign matter such as pebbles. The existence of the part is very effective. Alternatively, the side surface shape of the protruding end of the convex portion may be formed in a small arc shape or a thread chamfered shape (claim 4). In this configuration, when the saw blade for mowing is handled with a bare hand, the convex portion that protrudes most on the outer periphery is not a blade, that is, cannot be cut, so that it is difficult to injure the hand.

According to the first aspect of the present invention, the blade is prevented from coming into direct contact with foreign matter, and the life of the saw blade for mowing is extended more than before.
The invention according to claim 2 has an effect of further extending the protection period of the blade against contact with the foreign matter.
According to the invention of claim 3, the blade formed of a cemented carbide tip is maintained in a sharp state with no chipping or dropping off, and the life of the mowing saw blade having a cemented carbide tip blade is improved compared with the conventional one. There is an effect to extend significantly.
The invention of claim 4 has an effect of hardly injuring the hand.

It is a side view which shows 1st Embodiment of this invention. It is AA sectional drawing of FIG. It is the elements on larger scale of FIG. It is the elements on larger scale similar to FIG. 3 which shows 2nd Embodiment of this invention.

  A first embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the mowing saw blade 1 has a large number of, for example, thirty blade portions 4 in the rotation direction during use indicated by an arrow 3 at the periphery of a disk-shaped base metal 2. Have. As shown in an enlarged view in FIG. 3, the blade portion 4 is formed of a cemented carbide chip having a blade edge 5, and is fitted into a recess 6 provided in the base metal 2 and brazed. The cutting edge 5 has a scooping surface 7 with a scooping angle α, for example 5 °, and a clearance surface 8 with a clearance angle β, for example 8 °. That is, the scooping surface 7 forms a scooping angle α with respect to the center line 20 passing through the center of the base metal 2 and the cutting edge, and extends substantially toward the center. The flank 8 extends inward and rearward at a flank angle β with respect to the tangent line 10 of the cutting edge position of the cutting edge circle 9 passing through the cutting edges 5 of the plurality of cutting portions 4. In addition, the scooping surface 7 of the chip | tip (blade part 4), the flank 8, and both side surface 8a are ground. As shown in FIG. 2, both side surfaces 8 a are provided so as to protrude slightly from the plate surface of the base metal 2, are parallel to the plate surface, and have corners of about 90 ° on both sides with the scooping surface 7. Forming.

  In a general saw blade for mowing, the approximate shape of the blade portion is a repetition of a crest having a blade and a trough. However, in the saw blade 1 for mowing, the flank extending portion 11 extending substantially following the flank 8 of the blade portion 4 is gradually displaced inwardly and rearwardly away from the cutting edge circle 9, so that the valley portion It is distracted toward. A projecting portion 12 having a projecting end projecting from the cutting edge circle 9 is provided in the middle of the extension toward the valley portion. The convex portion 12 has a front surface in the rotational direction formed into a convex curved surface 13 obliquely forward and outward to reach the protruding end 14, and subsequently, the rear surface of the convex portion 12 suddenly extends toward the center side. It is formed in the rear extension 15. The protruding end 14 is rounded with a small radius, for example, about 0.1r so as not to become an edge in a side surface shape, that is, is formed in an arc shape. It is good also as a chamfering shape instead of this roundness. The protruding end circle 16 passing through each protruding end 14 is slightly larger than the cutting edge circle 9, and the radial dimension difference e is, for example, 0.5 mm. A curved portion 17 (a portion corresponding to the conventional valley portion) that is outwardly concave is formed after the rear surface extending portion 15. The curved portion 17 is directed outward, and is smoothly connected to a scooping surface extension portion 18 that is formed to extend following the scooping surface 7 of the subsequent blade portion 4. The recessed part 19 is formed by these. The rear surface extended portion 15 of the convex portion 12 and the scooping surface extended portion 18 of the blade portion 4 are in a state of facing each other.

  The saw blade 1 for mowing thus configured is used by being attached to a normal mower. The mechanism of mowing the grass is roughly considered as follows. Most of the grass that hits the saw blade 1 during the mowing operation first hits the front surface near the protruding end 14 of the convex portion 12, and the hit grass is bounced away so as to move away from the saw blade side. However, the action of returning to the original occurs by the reaction, and it is pressed to the saw blade side. As a result, most of the grass is formed in the recessed portion 19 (the front side position of the blade portion 4) composed of the rear surface extended portion 15 of the convex portion 12, the curved portion 17, and the scooping surface 7 and scooping surface extended portion 18 of the blade portion 4. Gets in and the grass that gets in is cut away. According to a practical test in which a conventional saw blade-like mechanism (a comparative example in which the convex portion 12 is not present but the other parts are almost the same) and a practical example using the first embodiment are compared, Since there is no difference in sharpness, even if the convex portion 12 is present, the grass enters the front side of the blade portion 4 well, that the grass that has entered the concave portion 19 is cut off by the blade, It was confirmed that the convex portion 12 hits the foreign matter on the front side of the blade portion 4 to protect the blade portion 4 from being hit by the foreign matter. The blades that directly cut the grass are the blades of the blade portion 4, that is, the front blades that are the portions of the blade edge 5, and the horizontal blades that are the corner portions on both sides of the scooping surface 7.

  The comparison test of life span is not performed because it is difficult to compare strictly because the variation of grassland conditions is large, but if it is assumed that mowing was continued under similar conditions, the sharpness gradually decreases in the comparative example, and appropriate In some cases, re-polishing may be performed at a certain time, but since the number of chipped or dropped portions increases, it is difficult to restore the sharpness by re-polishing. On the other hand, in Example 1, since the initial sharpness lasts long and the chip is not chipped or dropped off, the protruding end 14 of the convex portion 12 is worn and the protruding end circle 16 becomes slightly smaller than the cutting edge circle 9. Before, it can return to the state close to the initial state (new state) by re-polishing. Therefore, it can be said that it can be used for a long time.

  When it explains that the convex part 12 has protected the blade of the blade part 4, when there is a foreign object such as a small stone or a hard wooden piece, the convex part which forms the maximum outer diameter part and is on the front side of the blade Since the 12 protruding ends hit the foreign object, the foreign object jumps off. Therefore, the foreign object does not directly hit the blade, and the blade is reliably protected. In addition, when cutting the ground near concrete fences, gutter blocks, and grass near curbstones, a saw blade may hit the concrete fences or curbstones with care. However, also in this case, the convex part 12 hits and the saw blade side is repelled, and the blade of the blade part 4 is prevented from being damaged. Moreover, the reaction force when played is considerably smaller than that of a conventional saw blade for mowing. This is because the front side in the rotational direction of the convex portion 12 is a convex curved surface, so that the contact with the foreign material is rubbed, and is completely different from the state of biting or scratching when the conventional blade directly hits. .

  Thus, since the damage of the blade of the blade part 4 is prevented by the presence of the convex part 12, the sharpness of mowing the grass is kept good until the convex part 12 is worn and cannot protect the blade. . Even if the mowing saw blade 1 may be handled with bare hands, the hand is hardly injured by the cutting edge as in the prior art. This is because a minute roundness is formed at the protruding end 14 of the convex portion 12, so that the protruding end 14 of the convex portion 12 is not injured and the convex portion 12 is located on the front side of the cutting edge 5. You won't be injured with the blade. Even if it is actually stroked with the fingertips in the outer peripheral direction, no catch is felt.

  FIG. 4 shows a second embodiment. The saw blade 1a for mowing according to this embodiment is the same as the saw blade 1a except that the blade portion 4a is formed by a base metal portion, and the others are the same. Therefore, the same parts as those in the first embodiment are indicated by the same reference numerals in FIG. In addition, the saw blade 1a for mowing also has the same effect as the first embodiment because the convex portion 12 acts similarly.

DESCRIPTION OF SYMBOLS 1 Saw blade for mowing 2 Base metal 3 Arrow 4 Blade part 5 Cutting edge 6 Recess 7 Scooping surface 8 Relief surface 9 Cutting edge circle 10 Tangent 11 Relief surface extension part 12 Protrusion part 13 Curved surface 14 Projection end 15 Rear surface extension part 16 Projection end circle 17 Curved portion 18 Crawling surface extended portion 19 Recessed portion 20 Center line

Claims (4)

  The peripheral edge of the disk-shaped base metal has a large number of blade portions facing forward in a predetermined rotational direction, and the blade portion has a scooping surface extending toward the center of the base metal, and a large number of relief surfaces. In the saw blade for mowing that extends backward in the rotational direction while being gradually displaced inwardly from the blade circle passing through the blade edge of the blade portion of the blade portion, the extended portion of the flank face of the blade is directed outward from the middle to the blade edge. After being provided with a convex part protruding from a circle, the rear edge in the rotational direction of the convex part is extended from the protruding end part toward the base metal side and facing the extended part of the scooping surface of the next blade that follows. A saw blade for mowing which is formed by forming an outwardly concave curved portion in an extended portion of the scooping surface of the next blade.   The saw blade for mowing according to claim 1, wherein the leading edge in the rotation direction of the convex portion is formed into a curved surface that protrudes obliquely forward and outward from the flank face toward the protruding end portion. blade.   The saw blade for mowing according to claim 1 or 2, wherein the blade portion is formed of a cemented carbide chip and brazed.   The saw blade for mowing according to claim 1, 2, or 3, wherein the side surface shape of the protruding end of the convex portion is formed in a small arc shape or a thread chamfer shape.

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