JPH0130996Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is based on the sudden acceleration or deceleration of the engine or insufficient tightening force of the center bolt, and the mower blade is loosened due to shocks and vibrations to the mower blade during work. This invention relates to a mower blade attachment plate detachment prevention device for a brush cutter that can prevent the mower blade attachment plate for fixing the mower blade from detaching from the center bolt.

Conventionally, as a means for fixing the cutting blade mounting board of a brush cutter in a fixed position with a center bolt, for example, as shown in FIG. A suitable number of splines a carved on the outer periphery of a rotating shaft 4 which is fixed with bolts and rotatably supported in the gear housing 3 upward and downward are passed through the through hole b of the cutting blade mounting board 5. , the spline a is fitted into the grooves d ₁ and d ₂ carved in the inner peripheral edges of the through holes C ₁ and C ₂ at the center of the cutter bosses 6 ₁ and 6 ₂ that are brought into close contact with the upper and lower surfaces of the cutting blade mounting board 5. The lower part of the cylindrical collar 7 that is in close contact with the lower surface of the cutter boss 6 ₂ is fitted into the upper inner peripheral edge of the through hole e in the upper covering part u of the bearing housing 8, and the lower end of the through hole e is fitted. The threaded part f of the center bolt 9 inserted from above is screwed into and fixed to the female thread drilled at the center of the rotation shaft 4, and the covering 10 covering the outside of the center bolt 9 is welded to the ground plate 11. The bolt g passes through the bolt g, and its tip is screwed into the bearing housing 8. The cutting blade 12 is fixed to the cutting blade mounting board 5 with fasteners such as bolts and nuts, and the top cover 13 is fitted and fixed to the lower part of the gear housing 3. However, the mower blade mounting board 5 using the center bolt 9 as described above
In the case of the fastening means, the center may be damaged due to engine startup or sudden acceleration/deceleration during brush cutting work, or due to insufficient tightening force of the center bolt 9 itself, or due to shock or vibration to the cutting blade during work. bolt 9
As the brush cutter is used repeatedly, the blade gradually loosens, and the blade boss 6 ₂ that fits into the spline a of the rotating shaft 4 also swings, so the blade mounting plate 5 whose lower surface is supported by the blade boss 6 ₂ also remains in a fixed position. In extreme cases, the center bolt 9 may separate from the rotating shaft 4 and fall, and the cutting blade mounting plate 5 may also fall off. There is considerable danger of unexpected disasters for employees and passersby. Therefore, with the intention of rectifying the above-mentioned drawbacks, this invention was developed to improve the cutting blade mounting plate and the like.
The spline of the rotating shaft is fitted to the boss of the cutter held at the bottom, while a square collar is fitted from below to the flat washer that is in contact with the boss of the cutter below, and the square collar is fitted into the square hole in the center of this square collar. By screwing the male thread of the center bolt with the shaped part integrally formed into the female thread of the rotating shaft, and screwing the retaining bolt into the lower cutter boss through the through hole of the flat washer, the spline, flat A mower blade mounting board separation prevention device for a brush cutter that can prevent the mower blade mounting board from detaching by constantly maintaining the tightened state of the center bolt to the rotating shaft unless the washer, retaining bolt, square hole, etc. are damaged. This is what we are trying to provide.

An embodiment of this invention will be described below with reference to FIGS. 2 to 4. Below a gear casing 23 integrally formed with a connecting pipe 22 bolted to an outer conduction shaft pipe 21, a shape having an approximately inverted bowl-shaped cross section is provided. The center of the top cover 24 is fitted and fixed, and a spline s is carved on the outer peripheral edge of a rotating shaft 25 that is interlocked with a gear group (not shown) housed in this gear housing 23.
A through hole h to be drilled in the center of the cutting blade mounting plate T is fitted into the lower diameter reduced part r of the upper cutter boss 26 formed by the spline groove _s1 fitted to the cutting blade mounting plate T. T
and carving a spline groove _s2 in the center of the lower blade boss 27 that abuts the lower surface of the reduced diameter portion r, respectively;
The spline s is fitted into the spline groove _s2 , and a screw hole i is bored near the outer periphery. A square or hexagonal square hole j is formed in the center of the flat washer 28 that comes into contact with the lower surface of the lower cutter boss 27.
Further, a suitable number (three in this case) of elongated holes l are bored on the periphery of the square j, and a rectangular or hexagonal square collar 29 is fitted into the square holes j, and the retaining bolt 30 is inserted into the square hole j. It is made to pass through the elongated hole l and can be fastened to the screw hole i. Said square collar 2
Inside the bearing casing V that can hold the square collar 29
The center bolt 31 is attached to the bearing Y set below the
The square part m of the center bolt 31 is fitted into the square hole z of the square collar 29, and the male screw k at the tip is screwed into the female screw carved inside the rotating shaft 25.・By fixing, the rotating shaft 25, the cutting blade mounting plate T, the upper and lower blade bosses 26,
27, a flat washer 28, a square collar 29, and a center bolt 31 are integrally connected. A grounding cover 33 is integrally joined to a bolt cover 32 that covers the lower surface of the center bolt 31 by means such as spot welding, and a bolt 34 is inserted and tightened through this joint and the bearing housing V.

In addition, an appropriate number of sets (in this case, three sets) of plate nuts N, which can be separately prepared in advance, are placed inside the vicinity of the protrusion P that can integrally protrude from the outer periphery of the cutting blade mounting plate T, when the cutting blade mounting plate T is cast. It is molded and assembled as one piece. Then, the bolt 38 inserted through the flat washer 36 and the spring washer 37 is screwed into the plate nut N and secured to the through hole of the cutting blade 35 that comes into contact with the lower surface of the cutting blade mounting plate T, and the cutting blade 35 is fixed. It stays in place.
Note that the protrusion P is located on the outer peripheral edge q of the upper cover 24.
By surrounding the outside of the cutting blade mounting plate T, it functions as a wrapping prevention member, and prevents weeds such as vines from entering the inside of the cutting blade mounting plate T during mowing work. In the figure, 39 is an auxiliary rib of the cutting blade mounting plate T, W ₁ is a flat washer on the retaining bolt 30, and W ₂ is a spring washer above.

In this invention, the mower blade 35 performs mowing work as the rotary shaft 25 rotates and the mower blade mounting plate T rotates, but at this time, the spline s of the rotary shaft 25
, upper and lower blade bosses 26 and 27 of the cutting blade mounting plate T.
is spline fitted, while the lower cutter boss 2
7 Insert the square collar 29 into the square hole j of the flat washer 28 on the lower surface.
is fitted, and a retaining bolt 30 that can be inserted through a long hole l on the outer periphery of the square hole j is screwed and tightened into the screw hole i of the lower blade boss 27, and the corner of the square collar 29 is fitted. Since the rectangular part m _of the center bolt 31 is fitted into the hole z, the above-mentioned members are connected and _constructed as an integral rigid body. Unless the flat washer 28, retaining bolt 30, square hole j, etc. are damaged, the center bolt 31 maintains an integral connection with the rotating shaft 25 and does not loosen, so the cutting blade mounting board T Since there is no risk of accidental detachment from the rotating shaft 25, there is no risk of causing an unexpected disaster to nearby equipment, workers, or passersby during mowing work, and as a means to prevent detachment, particularly complex members are not used. Moreover, it does not require any complicated steps to assemble or disassemble.
Since the structure as a whole is not likely to become complicated, it can be constructed robustly and has practical benefits such as being able to carry out mowing work safely.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of the assembly members of a conventional cutting blade mounting board, Fig. 2 is a partially cutaway plan view of the proposed product, Fig. 3 is a sectional view taken along the -0-0 line in Fig. 2, FIG. 4 is an exploded perspective view. T...Mower blade mounting board, 25...Rotary shaft, 26...
Upper knife boss, 27...Lower knife boss, 28
...Flat washer, 29...Square collar, 30...Keeping bolt, 31...Center bolt, 35...
Cutting blade, i...screw hole, j...blade boss, square hole 27, k...male thread of center bolt 31, l...
Long hole of cutter boss 27, m...center bolt 31
Square part, s... Spline of rotating shaft 25, Z...
... Square hole with square collar 29.

Claims (1)

[Scope of claim for utility model registration] (1) In a bush cutter in which the tip of the center bolt is screwed and tightened inside the rotating shaft to which the upper and lower blade bosses and the cutting blade mounting board are spline-fitted, the lower screw hole A flat washer with a square hole and an elongated hole is placed on the lower surface of the cutter boss, and a retaining bolt that can be inserted into the elongated hole is screwed into the screw hole and tightened, and the corner of the flat washer is A detachment prevention device for a mower blade mounting board for a brush cutter, comprising a rectangular portion of the center bolt fitted into a rectangular hole of a rectangular collar to be fitted into the hole. (2) The device for preventing detachment from a mowing blade mounting plate of a brush cutter according to claim 1, wherein the square collar is formed in a hexagonal or square shape, and the square hole is formed in a square or hexagonal shape, respectively.