JPH0336635Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention relates to a mounting structure for detachably attaching a cutter bit to the helical blade of an earth auger head.

"Prior art and its problems" As shown in Fig. 5, the head of an earth auger used for excavating rock, etc. has a spiral blade b attached around an axial tube a. A cutter bit c... can be attached to the tip.

Conventionally, the above-mentioned cutter bit c is generally fixed to the spiral blade b by welding or the like.
In recent years, it has been desired that the cutter bit c can be easily replaced if it becomes worn or damaged, and for this reason, a structure in which the cutter bit c is detachably attached to the helical blade b has been proposed.
However, what has been proposed so far is
There were problems such as the mounting strength of the cutter bit c was not sufficient and the shape of the mounting part was complicated, so it was not sufficiently effective.

In view of the above circumstances, this invention provides a mounting structure for a cutter bit that can ensure sufficient mounting strength even though the shape of the mounting portion is relatively simple when the cutter bit is detachably attached to a helical wing. The purpose is to

``Means for Solving the Problems'' This invention involves forming a notched recess at the tip of the helical blade of the earth auger head, fixing a holder in the recess, and forming a supporting part formed on the holder on the cutter bit. In a cutter bit mounting structure in which the cutter bit is fitted into a groove to engage the cutter bit and are fastened together by a plurality of through bolts, the rear end surface and one side of the cutter bit are in surface contact with the holder. A rear wall portion and a side wall portion are formed, and a rear wall portion and a side wall portion are formed in the center portion of at least one of the upper surface and the lower surface of the support portion, and a thickness dimension of the support portion is parallel to the side wall portion and the thickness dimension of the support portion is on the side wall portion side. forming a step portion that becomes smaller; on the other hand, forming a step portion on the inner surface of the groove formed in the cutter bit that matches the step portion formed in the support portion;
It is characterized in that the fastening positions of the through bolts are line symmetrical across the stepped portion.

"Operation" In the mounting structure of this invention, the support part formed on the holder is fitted into the groove formed on the cutter bit, and they are fastened together with bolts. As a result, the cutter bit and the holder are engaged with each other with the rear end surface and one side surface of the cutter bit in surface contact with the rear wall and side wall portions of the holder, and furthermore, the stepped portions formed in the groove and the support portion are in surface contact with each other. This prevents the cutter bit from wobbling or shifting. Furthermore, since the bolts are installed separately on both sides of the stepped portion, the shearing force applied to the bolts is dispersed.

"Embodiments" Hereinafter, embodiments of this invention will be described with reference to the drawings.

1 to 3 show an embodiment of this invention, in which reference numeral 1 represents a holder and 2 represents a cutter bit. The holder 1 is formed into an L-shape by a rear wall part 3 and a side wall part 4, and
A support portion 5 is formed at the center in the height direction and is perpendicular to each of the rear wall portion 3 and the side wall portion 4.
This support portion 5 is a groove 9 of the cutter bit 2 (described later).
A stepped portion 6 parallel to the side wall portion 4 is formed at the center of the upper surface, and the upper surface of the support portion 5 is lowered by one level on the side wall portion 4 side. That is, the thickness dimension of this support portion 5 is the same as that of the side wall portion 4.
The sides are getting smaller. Further, a total of four bolt holes 7 are formed in this support part 5, two on each side of the stepped part 6, and furthermore, the tip surface of the support part 5 is chamfered on the top and bottom. .

On the other hand, the cutter bit 2 has a carbide tip 8 implanted at its tip, and a groove 9 shaped to match the support portion 5 of the holder 1 at its rear end.
An upper flange portion 10 and a lower flange portion 11 are left above and below this groove 9. This groove 9
is open on the rear end surface and both side surfaces of the cutter bit 2, and the upper surface of this groove 9 (upper flange portion 10
A stepped portion 12 corresponding to the stepped portion 6 formed on the upper surface of the support portion 5 is formed at the center of the lower surface of the supporting portion 5 . In addition, bolt holes 13 are formed in each of the upper flange portion 10 and the lower flange portion 11 at positions that match the bolt holes 7 formed in the support portion 5. ... has a counterbore to embed the bolt head and nut.

To attach the cutter bit 2 described above to the helical blade b of the earth auger head shown in Fig. 5,
First, the above holder 1 is fixed to the spiral blade b, and the cutter bit 2 is attached to the holder 1. In order to fix the holder 1 to the helical wing b, as shown in FIGS. 4 is placed on the side of the central axis a of the earth auger head, and the back surfaces of the side wall portion 4 and rear wall portion 3 are welded to the inner surface of the recess d. Then, fit the groove 9 of the cutter bit 2 into the support part 5 of the holder 1 fixed in this manner so that the bolt holes 7..., 13... align with each other, and as shown in FIG. 3, attach the bolts 14... is passed through and fastened with nuts 15.

By doing this, the cutter bit 2
Not only can it be detachably attached to the holder 1, but also sufficient attachment strength can be ensured. That is, according to this structure, as shown in FIGS. 2 and 3, the upper and lower surfaces of the support portion 5 and the groove 9
The inner surface of the cutter bit 2, the rear end surface and one side surface of the cutter bit 2 are in surface contact with the rear wall portion 3 and the side wall portion 4 of the holder 1, respectively, and the stepped portion 6 of the support portion 5 and the stepped portion 12 of the groove 9 are in surface contact with each other. Since the holder 1 and the cutter bit 2 are engaged in this state, the cutter bit 2 will not wobble or shift even if the cutter bit 2 receives a large load during excavation. In particular, since the stepped portions 6 and 12 are engaged with each other, the load applied to the cutter bit 2 from the lateral direction can be sufficiently resisted, and lateral displacement of the cutter bit 2 is effectively prevented. Also,
As a result, a large shearing force is not applied to the bolts 14, and breakage thereof can be prevented. Furthermore,
Since the bolts 14 are installed separately on both sides of the difference portions 6 and 12, the shearing force applied to the bolts 14 in the excavation direction is dispersed.

Further, in this structure, the shapes of the holder 1 and the cutter bit 2 are relatively simple, so that processing thereof is easy. Furthermore, since the holder 1 is fixed to the helical blade b and the cutter bit 2 is attached to the holder 1, complicated machining is not required for the helical blade b, as in the case where the cutter bit 2 is directly attached to the helical blade b. There is no need to carry out any process, and in the event that the holder 1 is damaged, it is sufficient to replace only that holder 1.

In the above embodiment, the step portions 6 and 12 are formed on the upper surface of the support portion 5 and the groove 9, but they may be formed on the lower surface of the support portion 5 and the groove 9. Alternatively, it may be formed on both the upper and lower surfaces, and in either case, the same effect can be obtained by making the thickness of the support portion 5 smaller on the side wall portion 4 side.

In addition, the holder 1 attached to the outermost periphery of the spiral blade b is provided with, for example, a fourth
As shown in Figure A, a carbide chip 20 is implanted,
Alternatively, it is desirable to provide sufficient wear resistance by applying hardfacing 21 as shown in the same figure.

``Effects of the invention'' As explained in detail above, according to this invention, the holder is fixed to the helical blade and the cutter bit is attached to the holder, and the rear end surface and one side of the cutter bit are attached to the back of the holder. The cutter bit can be easily attached and detached, and is sufficiently strong because the wall and the side wall are in surface contact with each other, and the stepped portions formed in the support and the groove are engaged in surface contact with each other. In particular, the engagement between the stepped portions can effectively prevent the cutter bit from shifting laterally. Therefore, although the shape is relatively simple, the cutter bit can be mounted sufficiently firmly without performing complicated processing on the helical blade. Furthermore, since the bolts are installed separately on both sides of the difference, the shearing force applied to the bolts in the excavation direction is dispersed, and breakage of the bolts is prevented.

[Brief explanation of the drawing]

Figures 1 to 4 are views showing an embodiment of this invention, in which Figure 1 is a perspective view before the cutter bit is attached to the holder, Figure 2 is a perspective view with the cutter bit attached, and Figure 3 is a perspective view of the cutter bit attached to the holder. 4 is a front sectional view thereof, and FIGS. 4A and 4B are perspective views showing other configuration examples of the holder, respectively. FIG. 5 is a front view showing the head portion of the earth auger. b...Spiral wing, d...Notch recess, 1...Holder, 2...Cutter bit, 3...Rear wall portion, 4...
...Side wall part, 5... Support part, 6... Step part, 7...
Bolt hole, 9...groove, 12...step, 13...
Bolt hole, 14...bolt.

Claims (1)

[Scope of utility model registration request] A notched recess is formed at the tip of the helical blade of the earth auger head, a holder is fixed in the recess, a supporting part formed on the holder is fitted into a groove formed in the cutter bit, and the holder and the cutter bit are engaged, and In the cutter bit mounting structure in which the cutter bits are fastened by a plurality of through bolts, the holder is formed with a rear wall portion and a side wall portion with which the rear end surface and one side surface of the cutter bit are in surface contact, and the support A step part is formed in the center of at least one of the upper surface and the lower surface of the part, and is parallel to the side wall part and such that the thickness dimension of this supporting part is smaller on the side wall part side, and on the other hand, it is formed in a cutter bit. The inner surface of the groove is formed with a stepped portion that matches the stepped portion formed in the support portion, and furthermore, the fastening position of the through bolt is symmetrical with respect to the stepped portion. Katsuterbit mounting structure.