JP2000116222A - Bush cutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bush cutter having a constitution capable of preventing the compaction of a nut caused by relative rotation of a reaping operation safety member and a reaping blade when the member is grounded and capable of readily carrying out the attaching and detaching operation of reaping blades and change of reaping operation safety members. SOLUTION: In this bush cutter having a constitution comprising a power transmission shaft 4 arranged in the interior of a case part positioned at the tip part of an operation lever 2, a reaping blade 5 integrated with the power transmission shaft 4 by fastening a nut 8 to a left screw part 4B formed at the tip of the power transmission shaft and a reaping operation safety member 9 forming a protecting cover of the nut 8 arranged between the nut 8 and a lower washer 7 so as to perform fastening by the nut 8, a projecting part 10 and a recessed part 11 to be engaged with the projecting part are engaged with the upper part of the reaping operation safety part to prevent the relative rotation of the reaping operation safety member based on the power transmission shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bush cutter, and more particularly, to a mounting structure for a cutting blade.

[0002]

2. Description of the Related Art A brush cutter is one of small working machines that can be carried and operated by a user. The bush cutter is used for bush cutting work on weeds, shrubs, and the like, and as a configuration therefor, there is a configuration provided with a mechanism for rotating a blade by a driving force of a small engine. The cutting blade is rotatably mounted in a case portion provided at the tip of the operating rod of the brush cutter. FIG. 6 is a cross-sectional view showing a mounting structure of a cutting blade of a conventional brush cutter, in which a case portion 3 is provided at the tip of an operating rod 2 of the brush cutter 1.
A power transmission shaft 4 interlocked with a transmission shaft 2 </ b> A inserted into the operation rod 2 is provided inside the case portion 3. The power transmission shaft 4 has a spline portion 4A formed at a position near the front end thereof, and a screw portion 4B formed at the front end portion. The screw portion 4B is formed in a relationship opposite to the rotation direction of the cutting blade 5, and is viewed from above so that the cutting blade 5 does not loosen when rotating counterclockwise when viewed from above. The lead direction is set counterclockwise, and a so-called left-handed screw is provided.

The cutting blade 5 has a power transmission shaft 4 on both sides thereof.
The lower washer 7 is fastened to the power transmission shaft 4 by the upper washer 6 and the lower washer 7 that can be spline-engaged with the power transmission shaft 4.
(Left-hand screw is provided.) To keep it from falling off. When the nut 8 is tightened, the lower washer 7 is pressed toward the opposing upper washer 6 across the cutting blade 5, whereby the cutting blade 5 is clamped by the upper and lower washers 6, 7. A mowing work safety member 9 is fitted into the power transmission shaft 4 from the front end side thereof, and is pressed and held on an end face of the lower washer 7 by a nut 8. That is,
The cutting work safety member 9 is mainly used as a protective cover for the nut 8 or for adjusting the cutting height, and is formed in a dish shape having a downward concave portion 9 </ b> A at a central portion inserted into the power transmission shaft 4. . When the nut 8 is fastened to the power transmission shaft 4, the mowing work safety member 9 is pressed against the end face of the lower washer 7 and is held integrally with the lower washer 7. In such a brush cutter 1, the upper washer 6 is fitted into the power transmission shaft 4, then the cutting blade 5, the lower washer 7 and the cutting work safety member 9 are fitted in this order, and the nut 8
Is fastened, the cutting blade 5 is sandwiched between the upper and lower washers 6 and 7, and can be interlocked with the rotation of the power transmission shaft 4.

[0004]

In the brush cutter 1 having the above structure, when the cutting work safety member 9 comes into contact with the ground during the cutting operation, the cutting blade 5 rotates relative to the rotation of the cutting blade 5. There was such a problem. That is, the reaping work safety member 9 is connected to the nut 8 which is in frictional contact with the ground.
Is rotated in the opposite direction to the cutting blade 5. Therefore,
The nut 8 advances along its own lead direction, and is fastened in the direction of pressing the reaping work safety member 9 against the so-called lower washer 7. For this reason, the nut 8 is firmly fastened to the harvesting operation safety member 8. On the other hand, the cutting blade 5 is a member to be replaced due to wear of the blade and the like, and the cutting member 9 is also a member to be replaced depending on the worn state. Therefore, the nut 8 is loosened at the time of replacement. However, if the nut 8 is firmly tightened as described above, labor for loosening and removing the nut 8 becomes enormous. Moreover, when the nut 8 is loosened with a wrench or the like, if the operating force for loosening the nut 8 is excessive, the corners of the nut 8 may be crushed by the operating force or a tool such as a spanner may be damaged. There is a possibility that the nut 8 cannot be loosened and rotated and cannot be removed.

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the conventional brush cutter, particularly the mounting structure of the cutting blade, an object of the present invention is to compact the nut by rotating the cutting work safety member relative to the cutting blade when the member is grounded. It is an object of the present invention to provide a bush cutter having a configuration in which the cutting blade can be prevented from being attached and removed, and the cutting safety member can be easily replaced.

[0006]

In order to achieve the above object, according to the present invention, there is provided a power transmission shaft provided inside a case portion (3) located at a distal end portion of an operation rod (2). An upper washer (6) and a lower washer (7) capable of sandwiching the cutting blade (5) are inserted into the cutting blade (5) from the front end thereof, and the cutting blade (5) is inserted by these washers (6, 7). ) Is clamped, a nut (8) is fastened to a left-hand threaded portion (4B) formed at the tip of the power transmission shaft (4), so that the cutting blade (5) is connected to the power transmission shaft (4). And a cutting work safety member (9) serving as a protective cover for the nut (8) is arranged between the nut (8) and the lower washer (7), and fastened together by the nut (8). A lower portion (7A) of the lower washer (7) or the lower portion (7A). A convex part (10) and a concave part (11) detachably fitted to the convex part (10) are formed on the upper part of the reaping work safety member (9) facing the convex part, and the convex part (10) and the concave part (11) are formed. Is fitted to prevent the reaping work safety member (9) from rotating relative to the power transmission shaft (4).

According to a second aspect of the present invention, in the brush cutter according to the first aspect, the convex portion (10) is formed by a cut-and-raised portion (12) formed on the side of the cutting work safety member (9). It is characterized by having.

According to a third aspect of the present invention, in the brush cutter according to the first aspect, the convex portion (14) or the concave portion (15) is provided at a lower portion of the lower washer (7) and at an upper portion of the cutting work safety member (9). In (9B), a plurality of strips are radially provided from the center position of the reaping work safety member (9).

[0009]

According to the first to third aspects of the present invention, the lower washer, which is one of the holding members of the cutting blade, and the cutting safety member facing the lower washer are formed with a convex portion and a concave portion which can be fitted to each other. Therefore, by fitting these convex portions and concave portions,
The relative rotation of the reaping work safety member can be prevented. Accordingly, the nut is not rotated in the tightening direction, so that the nut can be prevented from being firmly tightened by the relative rotation of the reaping work safety member. Moreover, in the second aspect of the present invention, since the protruding portion is formed by the cut-and-raised portion, it is possible to simultaneously mold the member on which the protruding portion is provided, thereby preventing an increase in cost. According to the invention described in the item 3, the area for receiving the load in the relative rotation direction generated when the mowing work safety member touches the ground can be increased to increase the rigidity of the convex portion and the concave portion.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a sectional view showing a structure of a cutting blade mounting portion of a brush cutter according to a first embodiment of the present invention. In the drawings after FIG. 1, the same members as those shown in FIG. 6 are denoted by the same reference numerals. In FIG. 1, a lower portion 7 </ b> A of a lower washer 7, which is one of the holding members of the cutting blade 5, has a projection 10 protruding toward a cutting work safety member 9 facing the lower washer 7.
Are provided in a pair (see FIG. 1 (B)) at positions facing each other with the center therebetween. A fitting hole (or hole) corresponding to the concave portion for fitting the convex portion 10 to the bottom surface 9B of the concave portion 9A is provided on the mowing work safety member 9 side opposite to the convex portion 10.
11 are formed.

Since the present embodiment has the above configuration,
The power transmission shaft 4 is inserted so that the lower washer 7 cooperates with the upper washer 6 to clamp the cutting blade 5. In this state, the lower washer 7
The reaping work safety member 9 is fitted into the power transmission shaft 4 so that the hole (or hole) 11 is detachably fitted to the projection 10 of the power transmission shaft 4, and is tightened toward the lower washer 7 by the nut 8. Since the lower washer 7 and the reaping work safety member 9 are maintained in a state in which the relative rotation is prevented by the fitting of the projection 10 and the hole 11, when the reaping work safety member 9 comes into contact with the ground during work. However, the nut 8 does not rotate due to the frictional engagement between the reaping work safety member 9 and the nut 8, so that the nut 8 is not firmly tightened.

According to the present embodiment, the cutting work safety member 9 is grounded only by providing the projection 10 and the hole 11 corresponding to the recess fitted to the projection 10 between the lower washer 7 and the cutting work safety member 9. In this case, the nut 8 is prevented from rotating around, so that the nut 8 is prevented from being compacted due to the rotation of the nut 8 along with the cutting work safety member 9, so that the nut 8 is easily loosened and the cutting blade 5
Can be easily replaced, and damage to a tool used when loosening the nut 8 can be prevented. Further, it is easy to replace the cutting work safety member 9 with a new one. In the above embodiment, as the configuration of the convex portion and the concave portion, the configuration in which the convex portion 10 is formed in the lower washer 7 and the hole 11 corresponding to the concave portion is formed in the reaping work safety member 9 has been described. However, the present invention is not limited to this configuration, and it is also possible to provide a hole (or hole) forming a concave portion in the lower washer 7 and provide a convex portion in the cutting safety member 9.

Next, another embodiment of the present invention will be described with reference to FIG. In the embodiment shown in FIG. 2, the structure of the convex portion and the concave portion provided between the lower washer 7 and the reaping work safety member 9 is as follows.
It is characterized by comprising a cut-and-raised portion and a hole (or hole) into which this is detachably fitted. In FIG. 2, the cutting safety member 9 formed by sheet metal processing has a cut-and-raised portion 12 erected toward the end face of the lower washer 7 at a position facing the lower washer 7. A pair (see FIG. 2B) is provided so as to face each other across the center. The cut-and-raised portion 12 is formed by pressing at the same time as the shaping work safety member 9 is formed. On the other hand, a hole 13 corresponding to a concave portion into which the cut-and-raised portion 12 is fitted is formed on the end face of the lower washer 7 facing the cut-and-raised portion 12.

Since the present embodiment has the above configuration,
When the lower washer 7 is inserted into the power transmission shaft 4 to hold the cutting blade 5, the cutting work safety member 9 is driven by the cut-and-raised portion 12 fitted into the hole 13 of the lower washer 7. It is fitted into the transmission shaft 4 and tightened by the nut 8. Also in this embodiment, similarly to the embodiment shown in FIG. 1, the lower washer 7 and the reaping work safety member 9 are provided with a cut-and-raised portion 11 corresponding to a convex portion and a hole 13 corresponding to a concave portion in which the lower portion is fitted. Thus, when the mowing work safety member 9 comes into contact with the ground during the mowing operation, it does not rotate relative to the rotation of the cutting blade 5. For this reason, even if the cutting work safety member 9 is in contact with the ground, the nut 8 is not firmly tightened.
Alternatively, the replacement work of the reaping work safety member 9 can be facilitated.

According to the present embodiment, the cut-and-raised portion 12 forming a convex portion among the convex portion and the concave portion provided between the lower washer 7 and the mowing work safety member 9 is formed by the cutting safety member 9.
Can be processed at the time of molding, so that there is no need to prepare a special member for preventing the relative rotation of the reaping work safety member 9, and it is possible to suppress the increase in cost and reliably prevent the relative rotation.

Next, another embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a plurality of radially formed keys 14 are detachably engaged with the plurality of radially formed keys 14 as a structure of a convex portion and a concave portion provided between the lower washer 7 and the mowing work safety member 9. And the use of a concave portion.
3 and 5, the lower end face of the lower washer 7 includes:
A plurality of keys 14 extending radially from the center are provided along the circumferential direction. On the other hand, a concave groove 15 with which the key 13 can be engaged is formed in the mowing work safety member 9 facing the key 14, as shown in FIGS.

Since the present embodiment has the above configuration,
A lower washer 7 is fitted to hold the cutting blade 5 with respect to the power transmission shaft 4, and the concave groove 15 is engaged with a key 14 of the lower washer 7 so that the cutting operation safety member 9 is engaged.
Is fitted into the power transmission shaft 4. When the cutting work safety member 9 is fitted, the nut 8 is screwed into the power transmission shaft 4 so that the lower washer 7 and the cutting work safety member 9 are connected to the upper washer 6 with the key 14 and the concave groove 15 engaged. And the cutting blade 5 is clamped. Since the lower washer 7 and the cutting work safety member 9 are integrated by the engagement of the key 14 and the concave groove 15, even if the cutting work safety member 9 is in contact with the ground during the work, the cutting work safety member 9 can be used as the cutting blade 5. , The nut 8 does not rotate, and the nut 8 is prevented from being firmly tightened. According to the present embodiment, since the convex portion and the concave portion are constituted by the key 14 and the concave groove 15, the load in the relative rotation direction generated when the reaping work safety member 9 is in contact with the ground is large. Since it is received by 14, the rigidity of the structure for preventing relative rotation can be increased, and the durability can be improved. In this embodiment, for example, in the case of being manufactured by die-casting or the like, the key 14 which is a convex portion is provided on the lower washer 7 side.
It is also possible to provide a concave groove in the lower washer 7 and to provide a key in the cutting work safety member 9. The key in this case is
Cut-and-raised pieces or beads formed by drawing can also be used.

[0018]

As is apparent from the above embodiments, in the inventions according to the first to third aspects, the lower washer, which is one of the holding members of the cutting blade, and the cutting safety member facing the lower washer. Since the protrusions and recesses that can be fitted to each other are formed, by fitting these protrusions and recesses, the relative rotation of the reaping work safety member can be prevented. Accordingly, the nut is not rotated in the tightening direction, so that the nut can be prevented from being firmly tightened by the relative rotation of the reaping work safety member. Therefore, at the time of replacing the cutting blade or the reaping work safety member, the nut can be easily loosened, so that an increase in labor and damage to the tool can be prevented, and the replacing operation can be performed easily. Moreover, according to the second aspect of the present invention, since the protruding portion is formed by the cut-and-raised portion, it is possible to simultaneously mold the member on which the protruding portion is provided, thereby preventing an increase in cost. According to the third aspect of the present invention, it is possible to increase the area for receiving the load in the relative rotation direction generated when the mowing work member touches the ground during the work, thereby increasing the rigidity of the convex portion.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a cutting blade mounting portion of a bush cutter according to one embodiment of the present invention, wherein FIG.
(B) is a bottom view of the main part.

FIG. 2 is a view showing a configuration of a cutting blade mounting portion of a bush cutter according to another embodiment of the present invention, and FIG.
(B) is a bottom view of the main part.

FIG. 3 is a cross-sectional view showing a configuration of a cutting blade mounting portion of a brush cutter according to another embodiment of the present invention.

FIG. 4 is a bottom view of a lower washer used for the cutting blade mounting portion shown in FIG. 3;

FIG. 5 is a bottom view of a cutting work safety member used for the cutting blade mounting section shown in FIG. 3;

FIG. 6 is a cross-sectional view for explaining a conventional structure relating to a cutting blade mounting portion of a brush cutter.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 brush cutter 2 operation rod 4 power transmission shaft 4B left screw portion 5 cutting blade 6 upper washer 7 lower washer 7A lower portion of lower seat surface 8 nut attached to left screw portion 9 cutting work safety member 10 convex portion 11, 13 Hole that forms a concave portion 14 Key that corresponds to a plurality of convex portions 15 Concave groove that corresponds to a concave portion

Claims (3)

[Claims] 1. A cutting blade (5) can be clamped from a distal end side of a power transmission shaft (4) provided inside a case portion (3) located at a distal end portion of an operation rod (2). The upper washer (6) and the lower washer (7) are fitted, and are formed at the tip of the power transmission shaft (4) while the cutting blade (5) is sandwiched by the washers (6, 7). The cutting blade (5) is integrated with the power transmission shaft (4) by fastening a nut (8) to the left thread portion (4B), and the nut (8), the lower washer (7), A mowing work safety member (9) forming a protective cover for the nut (8) between the nuts (8), and the nut (8) being fastened together by the nut (8), wherein the lower part of the lower washer (7) 7A) or the lower portion (7
A convex part (10) and a concave part (1) detachably fitted to the upper part of the above-mentioned mowing work safety member (9) opposed to A).
By forming 1) and fitting the convex portion (10) and the concave portion (11), the cutting work safety member (9) is prevented from rotating relative to the power transmission shaft (4). A brush cutter characterized in that it is made to do. 2. The brush cutter according to claim 1, wherein the projection (10) is formed by a cut-and-raised portion (12) formed on the cutting safety member (9). Brush cutter. 3. The brush cutter according to claim 1, wherein the projection (14) or the recess (15) is formed at a lower portion of the lower washer (7) and an upper portion (9B) of the cutting work safety member (9), A brush cutter characterized in that a plurality of strips are provided radially from a center position of the cutting work safety member (9).