JPH0647226Y2 - Cutting blade mounting device for brush cutter - Google Patents

Description

[Detailed description of the device] [Industrial applications]

TECHNICAL FIELD The present invention relates to a cutting blade mounting device that prevents accidental detachment of a mounted cutting blade in a brush cutter to which a cutting blade is detachably mounted.

[Prior art]

A brush cutter used for harvesting weeds and the like has an operating main rod having a small engine and a gear case attached to both ends thereof. A cutting blade presser is attached to the output shaft of the gear case, and the cutting blade is fixed by the cutting blade presser and a fastening washer. Then, the output from the small engine is input to the gear case via the transmission shaft that penetrates the inside of the operating main rod and is transmitted to the cutting blade. The inventors of the present invention have developed a brush cutter that can be easily attached and replaced with a cutting blade, and is equipped with a mechanism for preventing the cutting blade from falling off during high-speed rotation. It was introduced as a bulletin. As shown in FIG. 8, the brush cutter proposed in the prior application has a cutting blade presser 82 attached to an output shaft 81 of a gear case 80, and a cutting blade 84 is clamped between the cutting blade presser 82 and the fastening base 83. is doing. Fastening table 83
Is provided with a mounting hole 85 into which the output shaft 81 is loosely fitted, and a plurality of claw pieces 86 are formed on the inner surface of the mounting hole 85. A screw base 87 housed in the mounting hole 85 of the fastening base 83 can be screwed onto the output shaft 81. Further, the inside of the fastening base 83 is formed into a cavity 88, and the mover 89 is inserted into the cavity 88. The bottom surface of the cavity 88 is tapered, and a friction plate 90 is arranged on the opening side. When the cutting blade 84 rotates at high speed by the power transmitted from the output shaft 81, the mover 89 moves the cavity 88 radially outward by the centrifugal force. At this time, since the bottom surface of the cavity 88 is tapered, the mover 89 moved in the radial direction moves the friction plate 90 to the cutting blade 84.
Press on. As a result, the cutting blade 84 is fixed between the friction plate 90 and the cutting blade retainer 82 at a predetermined number of revolutions or more. On the other hand, when the cutting blade 84 is not rotating, the mover 89 moves toward the center of the cavity 89, and the force pressing the friction plate 90 disappears. Therefore, the cutting blade 84 can be easily replaced or attached / detached.

[Problems to be solved by the device]

In the brush cutter proposed in the previous application, the cutting blade 84 is attached to the gear case.
To attach to the output shaft 81 of 80, a female screw hole 91 is formed in one of a plurality of claw pieces 86 formed on the inner peripheral surface of the fastening base 83, and a click screw 92 is screwed into the female screw hole 91. is doing. The inside of the click screw 92 is hollow, and a push spring 93 attached to the click screw 92 causes the ball 94 to project to the extent that it does not fall off. When mounting the cutting blade 84, a screw base 87 screwed onto the output shaft 81 is inserted into the central hole of the cutting blade 80, and the central hole is fitted into the boss step of the cutting blade presser 82. Then, the fastening base 83 is fitted to the screw base 87, and the friction plate 90 is brought into contact with the cutting blade 82. In this state, the fastening base 83 is slightly rotated to fit the ball 94 on the fastening base 83 side into the notch 95 on the screw base 87 side. As a result, the cutting blade 84 is mounted on the output shaft 81 in a predetermined positional relationship. With this mechanism, the work of attaching and detaching the cutting blade 84 becomes extremely easy. However, the engagement between the fastening base 83 and the screw base 87 depends on the fitting of the ball 94 into the notch 95, and therefore, there is a risk of being released when an unexpected external force is applied. For example, if excessive force in the circumferential direction is applied to the fastening base 83, the notch
There is a possibility that the ball 94 may be detached from the 95 and the fastening base 83 may rotate with respect to the screw base 87. As a result, the fastening base 83 and eventually the cutting blade 84 fall off the output shaft 81, resulting in a very dangerous state. Therefore, the present invention has been devised to solve such a problem, and by adopting the engagement relationship between the fastening base and the nut member by the rigid fitting, the cutting blade is prevented from falling off. It is an object of the present invention to provide a brush cutter that is completely prevented and has improved safety.

[Means for Solving the Problems]

In order to achieve this object, the brush cutter of the present invention has a retainer fixed to the output shaft of the brush cutter in the rotational direction, a nut member screwed to a screw portion provided at the tip of the output shaft, and the nut. A fastening base arranged concentrically around the member, a friction plate having a flat portion facing the bottom surface of the presser from the inner peripheral edge press-fitted into the fastening base through the slope portion, and the output shaft of the output shaft. A moving element housed in the cavity of the fastening table in a radially movable state so as to press the friction plate toward the bottom surface of the pressing tool when the rotation speed increases, and The nut base is opened upwardly, and a plurality of recesses, both sides of which are defined by upright portions, are formed to radially project, and a plurality of inward projections fitted into the recesses are formed on the fastening base. Radially provided on the inner peripheral surface of the, against the elastic force of the friction plate Pressing the Kishime adhesive base on the pressing member,
After passing the recesses between the inner protrusions, rotate the fastening base with respect to the nut member so that the inner protrusions of the fastening base cross over the upright portions of the recesses. The fastening table is mounted by pressing the inward projections against the bottom surface of the recessed portion by the elastic force of the inclined surface portion of the friction plate.

[Action]

In the cutting blade attaching device of the present invention, the recessed portion whose upper side is opened is formed in the nut member, and the inward projection of the fastening base is fitted into this recessed portion. When mounting the fastening table, the inward projection of the fastening table is fitted into the recess while elastically deforming the friction plate. After fitting, the inward projection is pressed against the recessed portion by the elastic force of the friction plate, so that the fitted state is not released. This method is different from the method in which an elastic member such as a spring is used to lock the fastening base on the nut member, and the fastening base is rigidly held by the nut member in the rotational direction. Therefore, even if an unexpected force is applied, there is no positional deviation between the nut member and the fastening base, and the fastening base is secured at the desired position. Therefore, the cutting blade is maintained in the initial state without dropping or rattling. As described above, in the present invention, the fastening table can be attached with one touch. Moreover, unless the force that deforms the friction plate in the axial direction works, the attached fastening base does not come off from the recess portion of the nut member.

【Example】

Hereinafter, the present invention will be described in detail with reference to the drawings. In the cutting blade mounting apparatus of this embodiment, as shown in FIG. 1, an output shaft 11 is provided so as to project from the lower surface of a gear case 10 having a built-in reduction mechanism. The output shaft 11 has a large diameter portion 12 on the gear case 10 side, and a spline groove is formed therein. Further, the lower end side is connected to the small diameter portion 13, and a male screw portion is engraved. Disc-shaped blade holder 20 placed on the bottom side of gear case 10
Has a flange portion 21 formed at the periphery and a boss portion 22 formed at the center. Also, on the bottom of the cutting blade presser 20,
A step 23 is provided. This cutting blade presser 20 has an output shaft 11
By fitting the center hole into the spline engraved in the large-diameter portion 12 of, it is fixed to the output shaft 11. The fastening base 30 is loosely fitted to the small diameter portion 13 of the output shaft 11. A mounting hole 31 is formed in the center of the fastening base 30,
A plurality of inward projections 32 are provided on the inner peripheral surface of the mounting hole 31. For example, as shown in FIG. 2, three inward projections 32 are arranged at equal intervals in the circumferential direction of the mounting hole 31. The fastening table 30 is formed in a substantially bowl shape having a lower surface 33 having a gentle curved surface and a cavity 35 defined by a tapered bottom surface 34 which gradually becomes shallower toward the outer periphery. A boss portion 36 is provided in a donut shape at the center of the fastening base 30. The outer diameter of the boss portion 36 is slightly smaller than the outer diameter of the flange portion 21 formed on the cutting blade retainer 20. Also, the cavity
A rim 37 is formed on the outer peripheral edge of 35. The rim 37 may be provided with irregularities (not shown) for hanging fingers in order to facilitate the attachment / detachment work of the fastening base 30. The mover 40 is housed in the cavity 35 of the fastening base 30. As the mover 40, a steel ball or the like having a size capable of moving in the cavity 35 in the radial direction according to the rotation speed of the attachment / detachment table 30 is used. That is, the mover 40 is sized so as to be completely housed in the hollow portion 35 when it is located closer to the center of the fastening base 30 and slightly project from the hollow portion 35 when it is located radially outward. Instead of the steel ball, a roll, a wedge, or the like can be used as the mover 40. A donut-shaped friction plate 50 is attached to the opening side of the cavity 35. The inner peripheral edge 51 of the friction plate 50 is bent and press fit into the inner peripheral wall of the boss portion 36 of the fastening base 30. This allows
The friction plate 50 is integrated with the fastening table 30. Also, the friction plate 50
The outer peripheral edge 52 has an outer diameter equal to or larger than the outer diameter of the rim 37. As the friction plate 50, a spring material or the like formed in a donut plate shape is used. The friction plate 50 preferably includes, as shown in FIG. 1, for example, an inclined surface portion 53 that is inclined and rises from the inner peripheral edge 51, and a flat surface portion 54 that horizontally extends from the inclined surface portion 53. Further, in order to increase the elastic force of the friction plate 50, as shown in FIG. 3, a plurality of slits 55 may be radially provided from the inclined surface portion 53 to the flat surface portion 54. A nut member 60 is screwed into the small diameter portion 13 of the output shaft 11. On the end surface of the nut member 60, a plurality of protruding portions 61 protruding radially outward are radially formed. Above the protrusions 61 are recesses 62 whose upper parts are open. Both sides of the recessed portion 62 are divided into a large upright portion 63 and a small upright portion 64 as shown in FIG. The large upright portion 63 is provided on the side that receives an acceleration force when the fastening table 30 rotates, and the small upright portion 64 is provided on the side that receives the force when the fastening table 30 is decelerated and rotated. The recess 62 accommodates the inward projection 32 provided on the fastening base 30. The cutting blade 70 is formed into a donut shape, and the inner peripheral surface of the center hole thereof is in contact with the step portion 23 of the cutting blade presser 20,
It is fitted into the lower surface of the cutting blade presser 20. Further, the friction plate 50 contacts the other surface of the cutting blade 70. In the cutting blade mounting apparatus of this embodiment, the cutting blade 70 can be easily attached by screwing the nut member 60 into the small diameter portion 13 of the output shaft 11. That is, the inner projection 32 of the fastening base 30 is fitted into the recess 62 of the nut member 60, and the nut member 60 is screwed into the small diameter portion 13 of the output shaft 11. At this time, since the inner protrusions 32 are sandwiched on both sides in the circumferential direction by the large upright portions 63 and the small upright portions 64, the fastening base 30 and the nut member 60.
There is no relative rotation between and. With the fastening table 30 attached, the cutting blade 70 is sandwiched between the lower surface of the cutting blade presser 20 and the friction plate 50. At this time, the mover
40 is located on the central side in the cavity 35. Therefore, the mover 40 does not protrude from the cavity 35, and the friction plate 50 is
There is no force to press against 70. When the engine mounted on the brush cutter is started and the output shaft 11 is rotated, the cutting blade presser 20 and the fastening base fixed to the output shaft 11 are fixed.
30, and further the cutting blade 70 sandwiched between the cutting blade presser 20 and the fastening base 30 rotates. As the rotation speed of the fastening base 30 increases, the mover 40
The centrifugal force applied to is increased. Due to this centrifugal force, the mover 40 has a cavity 35 as shown by the two-dot chain line in FIG.
Moves radially inward. At this time, a part of the mover 40 protrudes from the cavity 35, and the friction plate 50 is pressed against the cutting blade 70. This pressing force increases as the rotation speed increases, so that the cutting blade 70 is reliably held between the friction plate 50 and the bottom surface of the cutting blade presser 20 especially in the high-speed rotation state. In addition, the inner protrusion 32 of the fastening base 30 is fitted in the recess 62 of the nut member 60.
Is housed in the nut member 60, and thus the output shaft.
The fastening base 30 will not be misaligned with respect to 11. For example, the force applied during acceleration is the large upright portion 63 of the nut member 60.
The force applied during deceleration is received by the small upright portion 64. Therefore, even when the cutting blade 70 hits a stone or a root of shrub during the cutting operation and the rotation speed greatly changes, the cutting blade 70 is secured in a desired positional relationship.
The axial movement of the fastening base 30 is restricted by the protrusion 61. The work of removing or replacing the cutting blade 70 is performed in a state where the rotation of the output shaft 11, the fastening base 30, etc. is stopped. At this time, the mover 40 is located on the center side in the hollow portion 35, and the force for pressing the friction plate 50 against the cutting blade 70 is not generated. In this state, the fastening table 30 is pushed up to a position where the inward projection 32 exceeds the small upright portion 64, and slightly rotated clockwise as it is. As a result, the fitting of the recess 62 of the nut member 60 to the inner protrusion 32 of the fastening base 30 is released, and the fastening base 30 and the friction plate 50 can be removed from the nut member 60. As a result, the cutting blade 70
Can be easily removed. Thereafter, for example, a new cutting blade is fitted on the stepped portion 23 of the cutting blade presser 20, and the fastening table 30 and the friction plate 50 are engaged with the nut member 60 in the reverse order of the above-mentioned procedure. In this way, the work such as mounting and replacement of the cutting blade 70 can be performed very easily with one touch without using a tool or the like. Moreover, the attached cutting blade 70 is securely held at a predetermined position and is prevented from coming off during the cutting operation. In the above embodiment, the cutting blade 70 is fixed to the cutting blade presser 20 and the fastening base.
I explained the type of brush cutter that is sandwiched between 30 and 30. But,
The present invention is not limited to this, and can be similarly applied to other types of brush cutters. For example, as shown in FIG. 5, the case 72 of the nylon cord cutter 71 may be attached to the fastening base 30 by fixing means 71 such as bolts and nuts. Even in this case, the nut member 60
Since there is no relative displacement between the fastening table 30 and
The case 72 is held in the desired positional relationship. Therefore, the bush cutting work using the nylon cord 73 extending in the radial direction from the case 72 is performed under stable conditions and is a safe work. Further, as the cutting blade, as shown in FIG. 6, a blade having a plurality of cutter blades 75 attached to a disc 74 by attaching screws 76 can be used. Further, as shown in FIG. 7, the fastening base 30 may be provided with ring-shaped projections 38 and 39 on the outer peripheral edge and the inner peripheral edge, respectively. In this case, the ring protrusions 38, 39
Since only the ground contacts the ground GL, the wear of the main body of the fastening base 30 is suppressed. As a result, it can be used for a long period of time. When not working, these ring projections 38, 39
Serves as a leg when the brush cutter is erected on the ground GL or when the line L connecting the ring-shaped projections 38 and 39 is inclined along the ground GL.

[Effect of device]

As described above, in the cutting blade attaching device of the present invention, the nut member and the fastening base are rigidly locked in the rotating direction, so that compared with the mechanism using the spring repulsion force. As a result, a relative positional deviation between the nut member and the fastening base is reliably prevented. Therefore, even when an unexpectedly large force is applied to the cutting blade, the cutting blade does not separate from the operating main rod, and the cutting operation can be performed safely. Moreover, since the cutting blade can be held without rattling, damage and deformation are suppressed, and the life of the cutting blade itself is extended. Furthermore, since the fastening table can be attached to the nut member with one touch, the cutting blade can be attached and detached very easily without requiring a special tool or the like. Thus, according to the present invention, it is possible to obtain a brush cutter having excellent handleability, safety and durability.

[Brief description of drawings]

FIG. 1 is a sectional view of a cutting blade mounting device according to an embodiment of the present invention, and FIG.
FIG. 4 is a bottom view thereof, FIG. 3 is a plan view of a friction plate, FIG. 4 is a sectional view taken along line IV-IV of FIG. 2, and FIGS. 5 to 7 are views for explaining other embodiments. FIG. 8 is a cross-sectional view of the cutting blade attachment device previously proposed by the present inventors. 11 …… Output shaft, 20 …… Crimping blade presser (presser), 30 …… Clamping stand, 32 …… Inward projection, 35 …… Cavity, 40 …… Mover, 50 ……
Friction plate, 51 …… Inner peripheral edge, 53 …… Slope, 54 …… Plane, 60…
… Nut member, 62 …… Recessed part, 63,64 …… Upright part, 70 …… Milling blade

Claims (1)

[Scope of utility model registration request] 1. A retainer fixed to the output shaft of a brush cutter in the rotational direction, a nut member screwed into a screw portion provided at the tip of the output shaft, and concentrically arranged around the nut member. Fastening base, a friction plate having an inner peripheral edge pressed into the fastening base and a flat portion facing the bottom surface of the presser through an inclined surface portion, and the friction plate when the rotational speed of the output shaft increases. So as to be pressed toward the bottom surface of the pressing tool, the movable element is housed in the cavity of the fastening table in a state of being movable in the radial direction, and the upper side is opened to the outer peripheral surface of the nut member. A plurality of recesses, both sides of which are divided by the upright portion, are formed so as to project radially, and a plurality of inward projections fitted into the recesses are provided radially on the inner peripheral surface of the fastening base. The pressing base against the elastic force of the friction plate. After passing the recesses between the inward projections, move the fastening table to the nut member so that the inward projections of the fastening table cross over the upright portions of the recesses. The cutting blade mounting device for a brush cutter, wherein the fastening table is mounted by rotating and pressing the inward projection against the bottom surface of the recess by elastic force of the inclined surface of the friction plate. .