JPS6334501Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to a mounting structure for a thread blade used as a cutting blade in a brush cutter.

[Conventional technology]

As cutting blades attached to brush cutters, in addition to disc-shaped cutting blades, flexible so-called string blades made of thin-diameter nylon cord are known. It is used for mowing lawns and weeds. The structure for attaching this thread blade to the brush cutter is to separately prepare a thread blade case that stores the thread blade wrapped around a bobbin, and then fix this to the grass blade mounting base on the brush cutter side with screws. Conventionally known. By the way, in the above conventional thread blade mounting structure,
The thread blade case is large because the thread blade is stored in a wound state, and the thread blade case has a complicated structure because it requires a means to fix the thread blade because it needs to be held in a state in which the thread blade is unrolled by the required amount. This had the disadvantage that it became bulky and expensive.

[Problem that the invention attempts to solve]

The present invention has been developed to solve the above-mentioned disadvantages.The present invention has a simple structure, allows the thread blade to be fixed without requiring special operations, and has excellent workability in adjusting and replacing the protruding amount of the thread blade. The purpose is to provide a blade mounting structure.

[Means to solve the problem]

For this purpose, the present invention includes an inner shaft rotatably supported within the main rod and rotationally driven by an engine, and a cutting blade mounting base connected to the tip of the inner shaft and rotatable together. In the brush cutter, a cup-shaped thread blade holder is provided on the cutting blade mounting base, and the thread blade holder has an insertion hole through which the thread blade can be inserted with both ends thereof extending outward, and an insertion hole inside the thread blade holder. and a locking part of a wedge-shaped space into which the middle part of the thread blade inserted into the insertion hole is bitten and locked, and when a tensile force is applied to the thread blade, the thread blade is locked in the locking part. The present invention is characterized in that it has a configuration in which:

【Example】

Hereinafter, the present invention will be specifically explained based on an embodiment shown in the drawings. In FIG. 1 showing the overall structure of the brush cutter according to this embodiment, reference numeral 1 is a main rod, and an engine 3 is attached to the base end of the main rod 1 via a clutch case 2 that accommodates a centrifugal clutch. In addition, a cutting blade unit 4, which will be described later, is provided on the tip side thereof, and a flexible inner shaft 5 is rotatably inserted and supported within the main rod 1, and is connected to the clutch from the engine 3. Rotational driving force passing through a centrifugal clutch (not shown) in the case 2 is transmitted to the cutting blade unit 4 via the inner shaft 5. In addition, as a mounting tool for the brush cutter, a shoulder belt 6 is installed near the base end of the main rod 1, and a vibration-proof rubber is wrapped around the base end of the main rod 1, sandwiching the shoulder belt 6. A handle rod 8 is provided on the distal end side of the main rod 1 and protrudes in the radial direction of the main rod 1. When the brush cutter is suspended by the shoulder belt 6, the grip portion 7 and the handle rod are attached to each other. 8, the cutting blade unit 4 at the tip of the main rod 1 can be swung back and forth, left and right. Furthermore, an accelerator lever 10 is pivotally attached to the vicinity of the gripping portion 7 via a bracket 9 so as to be grippable and operable, and this lever 10 is linked via an operating cable 11 to a throttle (not shown) of the engine 3. This makes it possible to control the engine speed, and the above configuration is almost the same as the conventional one. As shown in FIG. 2, the cutting blade unit 4 includes a support tube 12 that fits into the tip of the main rod 1 and is tightened and fixed by the slotted portion thereof, and a bearing 13 inside the support tube 12. The main members are a connecting shaft 14 that is rotatably supported while being prevented from coming off, and a cutting blade mounting base 15 spline-coupled to the distal end of the connecting shaft 14.
4 is provided with a square hole 16 on the base end side and is connected to the tip of the inner shaft 5 through the square hole. The distal end of the connecting shaft 14 protrudes from the support tube 12, and the cutting blade mounting base 15 is spline-fitted thereto, and the thread blade holder 17 and presser plate 18 are attached to the distal end in this order. It is fitted externally. A tightening nut 19 is screwed onto the tip of the connecting shaft 14, and by tightening this nut 19, the thread blade holder 17 is pressed against the cutting blade mounting base 15 via the holding plate 18, and the cutting blade is tightened. By locking the mounting base 15 to the inner ring end surface of the bearing 13, these mower blade mounting base 15, thread blade holder 17, and presser plate 1
8 is integrated with the connecting shaft 14. A thread blade holder 17 is attached to the cutting blade mounting base 15.
A boss protrusion 20 for centering is formed to fit on the back surface of the thread blade holder 17, thereby holding the thread blade holder 17 in a concentric state with the cutting blade mounting base 15. Next, the thread blade holder 17 has an inverted concave cup shape in appearance, and has a pair of thread blade insertion holes 17a, 1 extending in the peripheral wall in the diametrical direction, as shown in FIG.
7a are arranged at two locations facing each other. and,
This insertion hole 17a has guide grooves 17b and 17c along the axial direction formed on the outer periphery and the inner periphery of the peripheral wall.
The grooves 17b and 17c have side walls tapered so as to be continuous with the insertion hole 17a. Note that the insertion holes 17a, 17a are
Depending on the diameter of the thread blade, for example, a plurality of pairs having diameters of 1.5 mm and 2.5 mm may be formed. On the other hand, at the bottom of the recess of the thread blade holder 17, a ring-shaped groove 22 is formed around a circular platform 21 that comes into contact with the presser plate 18. A space 23 is formed between the part 18a and the thread blade holder 17. This space 23 has a wedge-shaped cross-sectional shape in which the outer peripheral side of the presser plate 18 is open because the ring-shaped groove 22 has a gently tapered surface 22a that is continuous with the circular platform 21,
Its size is large enough to hold the thread blade 24. The presser plate 18 is formed to be slightly larger in diameter than the cutting blade mounting base 15, and has a peripheral edge 1 on its end face on the thread blade holder 17 side.
A ring-shaped contact portion 18d is formed by a taper relief portion 18b of about 10 degrees formed at 8a and a circular relief portion 18c formed at the center.
The presser plate 18 is in contact with the circular base portion 21 of the thread blade holder 17 at a point d. In the above configuration, the thread blade 24 is inserted and attached to the insertion holes 17a, 17a formed in the peripheral wall of the thread blade holder 17. In this case, since guide grooves 17b and 17c having tapered side walls connected to the insertion hole 17a are formed around the insertion hole 17a, the thread blade 24 can be inserted smoothly. The thread blade 24 mounted in this way has its middle portion attached to the thread blade holder 1.
7 in the diametrical direction, but this intermediate portion bypasses the periphery of the presser plate 18 to form a wedge-shaped space 23.
Both ends of the thread blade 24 are pulled out from the peripheral wall of the thread blade holder 17 by the same amount. Note that the thread blade 24 is usually formed of a nylon cord or the like having a certain degree of flexibility and elastic restoring force to the stretched state, so that the intermediate portion thereof is connected to the wedge-shaped space 2.
There is no chance of accidentally deviating from 3. During use of the brush cutter with the thread blade 24 attached in this way, the thread blade 24 rotates together with the thread blade holder 17 due to the rotational driving force of the engine 3 transmitted via the inner shaft 5. edge,
Centrifugal forces in opposite directions act on both ends of the thread blade 24, and the balance causes a tensile force to act on the middle part of the thread blade 24, causing the thread blade 24 to bite strongly into the wedge-shaped space 23. Therefore, due to the wedge effect, the middle part of the thread blade 24 is securely fixed to the thread blade holder 17, and even if resistance is applied to both ends of the thread blade 4 when mowing lawns or weeds, the thread blade 24 will not come off. do not have. Note that the boss protrusion 20 provided on the cutting blade mounting base 15 is sufficient as long as it can center the thread blade holder 17, but the diameter and protrusion amount of the boss protrusion 20 may vary depending on the mounting of the disc-shaped cutting blade. If it is made to correspond to the boss hole, a normal disc-shaped cutting blade can be installed in place of the thread blade 24, and its installed state is shown in FIG. In this case, the disc-shaped cutting blade 25 fits into the boss protrusion 20 of the cutting blade mounting base 15, and the cutting blade mounting base 15
and a ring-shaped contact portion 18d of the holding plate 18, which has a slightly larger diameter than this, and is fixed to prevent it from coming off. Further, in this embodiment, the presser plate 18 is disk-shaped, but the point is that the thread blade holder 17 can be fixed, and the thread blade 24 can be clamped between it and the front bottom of the thread blade holder 17. Since any shape can be used as long as it can form the wedge-shaped space 23, the external shape of the presser plate 18 is not limited to a circle, and any shape such as an oval shape, a triangle with rounded corners, or a quadrilateral can be selected. Furthermore, although the tapered surface 22a for forming the wedge-shaped space 23 is provided at the inner bottom of the recess of the thread blade holder 17, such a tapered surface 22a is provided on the presser plate 18 side, and the inner bottom of the recess of the thread blade holder 17 is It may also be formed into a flat shape. Furthermore, the wedge-shaped space does not necessarily need to be formed by the thread blade holder 17 and the presser plate 18, and if the inner bottom of the recess of the thread blade holder 17 is made flat, the presser plate 18 may be made slightly thicker. A wedge-shaped groove may be formed on the outer circumferential surface of the holding plate 18, or if the presser plate 18 is a normal washer, a similar wedge-shaped groove may be formed on the circumferential wall of the circular platform 21 within the recess of the thread blade holder 17. You can do it like this.

[Effect of the idea]

As explained above, according to the present invention, the thread blade holder has an insertion hole through which the thread blade is inserted with both ends thereof extending outward from the holder, and a thread blade in the holder when a tensile force is applied to the thread blade. Since the structure may include a locking portion having a wedge-shaped space into which the thread blade is bitten and locked, the structure is extremely simple and suitable for weight reduction and mass production. In particular, when using a brush cutter equipped with a thread blade, tensile force is applied to the middle part of the thread blade due to the centrifugal force that accompanies the rotation of the thread blade holder. Since the thread blade is inserted into the wedge-shaped space and securely fixed, there is no need for a separate thread blade fixing member, and the danger of the thread blade coming off from the thread blade holder during use of the brush cutter can also be avoided. Also,
Since the fixing action of the thread blade is obtained by the action of biting into the wedge-shaped space, the release operation is relatively easy, making it easy to adjust the amount of protrusion of both ends of the thread blade or when replacing the thread blade. Effects such as excellent workability can be obtained.

[Brief explanation of drawings]

Fig. 1 is an overall side view with some parts omitted of a brush cutter according to an embodiment of the present invention, Fig. 2 is a partially sectional side view of the main parts, and Figs. 3 a and b are a thread blade holder. FIG. 4 is a partially sectional side view of the main part when a disc-shaped cutting blade is attached. 1... Main rod, 3... Engine, 4... Cutting blade unit, 5... Inner shaft, 12... Support tube,
14...Connection shaft, 15...Mower blade mounting base, 17
... Thread blade holder, 17a ... Insertion hole, 18 ... Pressing plate, 18a ... Peripheral part, 18b ... Taper relief part, 22 ... Ring-shaped groove, 22a ... Tapered surface,
23... Wedge-shaped space, 24... Thread blade, 25... Disc-shaped cutting blade.

Claims (1)

[Scope of utility model registration request] A brush cutter comprising an inner shaft rotatably supported within a main rod and rotationally driven by an engine, and a cutting blade mounting base connected to a distal end of the inner shaft and rotatable together. A cup-shaped thread blade holder is provided on the base. and a locking portion having a wedge-shaped space into which the intermediate portion is bitten and locked, and the thread blade is configured to be locked at the locking portion when a tensile force is applied to the thread blade. Thread blade attachment structure.