JPH0316957Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a removable excavation blade such as a casing auger that excavates the ground in a circular manner for drilling holes and the like.

[Conventional technology]

The welded drilling bit of the casing auger is troublesome to repair when the cutting edge is worn out or broken, which increases the operation loss of the excavator. There is a tendency for excavation blades in which the bit can be attached and detached to be more frequently used, and are made up of three elements: a bit with a bit and a fixing bolt for fixing the bit to the holder of the bit.

As a conventional technique for such a digging blade, for example, there is one proposed by the present applicant in Utility Model Application No. 125586/1986 or Application No. 63844/1988.

In the former application, as shown in FIGS. 5 and 6, the holder 1 is provided with a T-slot 2, and the bit 3 is provided with a supported portion 4 having a cross-sectional shape that matches the T-slot 2. They are fitted together and the bit and holder are secured with bolts 5.

In addition, those according to the latter application are shown in Figures 7 to 9.
As shown in the figure, the holder 1 is provided with a groove 6 and a groove 7 that cuts out the front edge of each of the front and rear walls in the rotational direction defined by this groove, and the bit 3 is fitted into the groove 6 to be supported. It has a structure in which the front part 4' has a convex part 8 that fits into the notched groove 7, and the two parts are fitted together and fastened with bolts 5, and in both cases, the load is transmitted from the bit to the holder. Therefore, the components are less likely to be damaged by the digging blade, and the bits can be easily replaced because all that is required is tightening and removing the bolts.

[Problem that the invention attempts to solve]

In the above-described excavating blade, the excavating radial dimension A of the bit 3 is smaller than the same-direction dimension B of the holder 1, and therefore, the opposite-handed excavating blades are arranged in a staggered manner in the circumferential direction, and the radial dimension A shown in FIG. A method is adopted in which the excavation width C is made larger than the holder dimension B.

However, if this method is adopted, a considerable excess portion will be excavated compared to the required excavation width, which is the value obtained by adding approximately 10 mm to the wall thickness D of the casing pipe K. Bit dimension A and holder thread allowance E
There is a lower limit in terms of strength, and in the case of a staggered arrangement, it is necessary to arrange the bits with some overlap, so the required excavation width is, for example, 50~
The actual excavation width when 60 mm is 80 to 100 mm.

In this way, if the excavation width becomes unnecessarily large,
Naturally, the digging resistance increases and the digging speed decreases.
Furthermore, the wear of the cutting edge of the bit accelerates, shortening the life of the bit.

In order to reduce excavation resistance, this idea ensures sufficient resistance to the three loads that are particularly problematic with removable excavation blades: pressing load during excavation, excavation load (rotational force), and lateral load. The purpose is to reduce the excavation width to the necessary minimum.

[Means for solving problems]

In this invention, in order to eliminate the above-mentioned problems, as shown in FIGS. 1 and 3, the holder 10 is
The dimensions A and B between the inner and outer surfaces of the bit 20 (radial dimension of the casing pipe) are made equal to or slightly larger than the thickness D of the casing pipe K.

Furthermore, cutout grooves 11 that open at the tip of the holder are formed symmetrically on the inner and outer surfaces of the holder 10 with reference to the ribs 12 between the grooves.

On the other hand, the bit 20 having the blade portion 21 is provided with a clevis groove 22 for receiving the rib 12 of the holder and an insertion portion 23 into the notch groove 11. In addition, an insertion portion 23 divided into two by the clevis groove 22
has a shape that almost fits into the notch groove 11. That is, as shown in FIG. 2, the notch groove 11 is
The surface 13 is made parallel to the direction of the pressing load R, and the surface 14 facing the surface 13 is set at α with respect to a line parallel to R.
Since the slanted surface is inclined at an angle of
Also, the front surface 24 in the rotation direction is parallel to R, and the rear surface 25 in the rotation direction has a shape having an inclination angle of α.

Further, a bolt hole 15 is provided in the middle of the rib 12, while a countersunk hole 26 is provided in the insertion portion 23 to accommodate the countersunk head of the bolt on one side, and a screw hole 27 is provided in the other side for screwing the threaded portion of the bolt. A bit is provided corresponding to a bolt hole 15, and a bit housed in the holder is fixed with a countersunk bolt 16.

In addition, in part A of Figure 3 and part B of Figure 2,
The holder and the bit are provided with the flexibility to move relative to each other in the R direction from the normal assembly position, and the bolt hole 15 is provided with the bolt 16 in order to avoid or minimize load transmission via the bolt 16. Make it sufficiently larger (usually about 2 mm) than the diameter of the A bush 17 is provided as necessary to prevent the bolt 16 from loosening, and is made of an elastically deformable material such as rubber or soft resin.

Incidentally, FIG. 4 shows a casing auger equipped with this excavating blade.

[Effect]

If the removable excavation blade is configured as described above,
Within a limited narrow range, the three loads simultaneously applied to the cutting edge, lateral load Q in Figure 3, pressing load R, and excavation load T in Figure 2, are widely distributed and transmitted from the bit to the holder, resulting in a concentrated load. Less likely to cause damage to the load transfer surface.

That is, considering the load during excavation, the load R due to pressing from above and the excavation load T due to rotational force are combined, and the maximum is approximately in the S direction. On the other hand, the surfaces 14 and 25 that transmit the resultant load S are inclined in a direction approaching perpendicular to the direction of the load S.
The contact surface pressure between the two surfaces does not become extremely large, and fatigue due to high surface pressure is suppressed. In addition, surfaces 14 and 25
An appropriate angle α is 10 to 40°, more preferably 15 to 40°. If the inclination α is too small, the wedge effect of the fitting portion becomes excessive, causing seizure due to friction and making it difficult for the bit to come off from the holder after a load is applied. On the other hand, if α becomes too large, wear and deformation are likely to occur in the portion indicated by C in FIG. 2, probably because the load on the end face side increases.

Next, against the lateral load Q, the contact portions between the surfaces 13 and 24 and between the surfaces 14 and 25 work effectively to protect the rib 12, which is most concerned about strength. In other words, when α is 0°, the lateral load Q is concentrated on the tip of the rib and parts A' and A' that are particularly susceptible to concentrated loads, and is directly transmitted from the bit to the rib. Clutches occur at the corner edges of the ribs, making it easy for the ribs to come off. However, with the structure of this invention, when the loads R and S are applied, the notch groove 11 and the insertion part 23
A wedge effect occurs between surfaces 13 and 24 and 1.
The contact pressure between 4 and 25 is increased, so that most of the lateral load is supported by the frictional force generated between these surfaces, and no large load is transmitted to the rib.

In addition, since the bolt 16 has sufficient flexibility with the hole 15, it hardly contributes to load transmission.
Well protected from loads.

Furthermore, when excavating hard rock layers, the bolt 16 tends to loosen due to vibrations and shocks propagated from the cutting edge, but with the elastic bushing 17, the bushing contacts the bolt and increases the rotational resistance of the bolt. At the same time, the bolt can be protected and the bolt can be prevented from loosening.

〔effect〕

As mentioned above, according to this invention, the load transmission surface at the fitting part of the bit and the holder is devised to sufficiently protect the rib of the holder, which is weakest against the load, from the load. , it becomes possible to reduce the excavation width, which had been unavoidably widened due to the use of a holder wider than the blade width, to the necessary minimum, thereby reducing the excavation resistance and increasing the excavation speed. For example, when using the excavation blade shown in Figure 7, the excavation width is 80~
It used to take about 80 minutes to drill a 5m deep annular hole in slate with a diameter of 100 mm, but with this invention, the drilling width has been reduced to 50 to 60 mm, and the drilling time under the same conditions is about 50 minutes. shortened to minutes.

In Fig. 3, the top of the cutting edge is left-handed, but for hard rocks, it is more effective to install right-handed bits at regular intervals within the width D.

In this way, this invention not only significantly shortens the construction period, but also significantly extends the bit life due to the reduction in unnecessary excavation, which has the effect of reducing maintenance costs. .

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of the digging blade of this invention, Fig. 2 is a side view of its assembled state, Fig. 3 is a sectional view taken along line X-X in Fig. 2, and Fig. 4. is a perspective view showing how it is attached to the casing pipe, Fig. 5 is a side view of a conventional excavating blade, and Fig. 6 is its Fig. 5 Y-
7 is a side view of another conventional excavating blade, FIG. 8 is a front view in the direction of rotation, and FIG. 9 is a sectional view taken along the Z-Z line in FIG. 7. be. 10... Holder, 11... Notch groove, 12... Rib, 13, 14... Surface of notch groove, 15... Bolt hole, 16... Countersunk bolt, 17... Bush, 20
... Bit, 21 ... Blade part, 22 ... Clevis groove, 23 ... Insertion part, 24 ... Rotation direction front surface,
25... Rotation direction back, 26... Counterbore, 27
...screw hole.

Claims (1)

[Scope of claims for utility model registration] (1) A holder welded to the tip of the casing pipe;
The dimensions between the inner and outer surfaces of the bit having a cutting part are made approximately equal to the thickness of the casing pipe, and the holder and the bit have a cutout groove on the inner and outer surfaces of the tip side of the holder to receive a part of the bit. A clevis groove is provided in each of the bits to receive the ribs left between the notch grooves from the rear end so that the casing pipe can be inserted and removed in the longitudinal direction. The part of the groove surface of the above-mentioned notched groove that supports the surface is inclined in a direction approaching perpendicular to the direction of the combined load of the pressing load and rotational force during excavation, and is screwed onto the bit by crossing the above-mentioned clevis groove. A removable excavating blade for construction machinery, wherein the bit is fixed to a holder by passing a countersunk bolt through a bolt hole having a diameter larger than the countersunk bolt provided in the rib. (2) The scope of the utility model registration claim, characterized in that the inclination angle of the back surface of the bit and part of the groove surface of the notch groove in the fitting portion with respect to an axis perpendicular to the rotational direction of the casing pipe is 10 to 40 degrees. The removable digging blade for construction machinery as described in item 1.