JPS624626Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a leading bit fixing device in a shield excavator.

Conventionally, in shield excavators (including various types of shield excavators such as mechanical excavation shields, muddy water shields, and earth pressure shields) that have a rotating face plate, the bits are worn out when digging in hard or gravel layers. There are many cases where the amount of excavation decreases due to cracking or chipping, forcing the bit to be replaced midway through.

For this reason, recently, in addition to the usual cutter bit, a leading bit has been attached to the face plate facing the face to cut relief grooves before cutting the ground in hard layers, and to loosen the gravel in advance in gravel layers. , methods are being taken to reduce the load on the katterbit and extend its life.

However, in this case, the leading bit is currently welded to the face plate, and as the excavation progresses and the leading part of the leading bit wears out, the damage to the cutting bit rapidly accelerates.
It is practically impossible to excavate the normal excavation distance of ~1200 m without changing bits.

In addition, when replacing bits, it is customary to construct an intermediate shaft and perform the replacement inside the shaft, or to use auxiliary methods such as chemical injection and pressurized air, and a worker comes out in front of the face plate to perform the replacement. The current situation is that this poses great risks and costs a lot of money.

This idea was made in consideration of the above points, and the leading bit, which was conventionally welded, was fixed with a pin, and it was possible to construct a vertical shaft as before.
This allows the advance bit to be replaced safely and quickly from inside the machine without using any auxiliary methods, and by restoring digging power, it enables long-distance excavation in hard and gravel layers.

The contents of this invention will be explained below with reference to the attached drawings.

FIG. 1 shows the layout of each bit on the face plate 1. Each bit is arranged at the edge of the slit 2 that takes in earth and sand, the cutter bit 3 is arranged on one side of the slit 2, and the leading bit 4 is arranged on the opposite side. In this case, these two types of bits 3 and 4
are arranged concentrically on the face plate 1, and each leading bit 4 precedes the cutter bit 3 by α on the face side, as shown in FIG.
Each of the bits 3 and 4 is equipped with a tip 5 made of cemented carbide, which is advantageous in terms of wear resistance.

Now, in this idea, regarding the leading bit 4,
Previously, it was welded to the face plate 1, but now it is an insert type from the inside of the machine toward the face side.
It is unique in that it is attached using a pin-fixing method.

For this purpose, a leading bit mounting hole 6 is drilled in the corresponding location of the face plate 1 as shown in Fig. 3, and a cylindrical shank holder 7 is fixed to the back side of the face plate 1 by welding or the like. has been done. This cylindrical shank holder 7 is provided so as to surround the leading bit mounting hole 6, and the width dimension of its inner diameter is slightly larger than the width of the leading bit mounting hole 6. Correspondingly, the shank 40 of the leading bit 4 is located on the rear end side 40b rather than the front end side 40a where the cemented carbide chip 5 is located.
is said to be slightly thicker, and the stepped part 4 in the middle of the shank
1 serves as a stop for the face plate 1.

Such a leading bit 4 has its leading end side 40a
is passed through the leading bit mounting hole 6 on the side of the face plate 1, and the rear end side 40b is fixed on the back side of the face plate 1 with a pin 8 so that it can be attached and removed. In this case, a bolt is used as the pin 8, and the bolt passes through each pin hole 9 on the shank holder 7 side and the leading bit 4 side, and its tip is fixed by a nut 10 and a split pin 11.

Therefore, if the leading bit 4 needs to be replaced, it is sufficient to remove the pin (bolt) 8 and replace the leading bit 4 with a new one, and the replacement can be easily performed from the internal drum side. In this case, in practice, the slit 2 of the face plate 1 is closed with a slit opening/closing plate and the face plate 1 is pressed down before the replacement work is performed, and the work is performed below the groundwater level. Of course, if there is a concern that groundwater may infiltrate into the drum, the work must be carried out while draining water using a pump.

However, in this invention, the leading end side 40a of the leading bit 4 is passed through the leading bit mounting hole 6 on the side of the face plate 1, and the rear end side 40b of the leading bit 4 is connected to the pin 8 on the back side of the face plate 1. Since it is fixed in such a way that it can be installed and removed freely, the leading bit 4 can be easily and safely replaced, that is, it can be replaced from inside the machine without requiring an intermediate shaft or auxiliary construction method, as well as the following effects. You can get many benefits.
For one thing, according to the work at the time of replacement, the preceding bit 4
By extracting bits from inside the machine and measuring the amount of wear, it is possible to arrange the bits early and take into consideration the work process. Since the force can be restored, it is possible to perform long-duration excavation in hard layers and gravel layers at high depths, and furthermore, the concrete in the mirror part of the starting and reaching shafts can be crushed by advance bit 4. This has the effect of omitting the work of chiseling the mirror (removing concrete from the mirror part) when starting and arriving.

[Brief explanation of the drawing]

Figure 1 shows the layout of the bits on the face plate, Figure 2 shows the leading state of the leading bit, and Figure 3 shows the mounting state of the leading bit according to this invention.A is a front view, B is a front view. Side view, C is a plan view. 1... face plate, 3... cutter bit,
4... Leading bit, 6... Leading bit mounting hole, 8
……pin.

Claims (1)

[Scope of utility model registration request] In a shield excavator in which a cutter bit and a leading bit that precedes the cutter bit on the face side are attached to the face plate facing the face plate, a leading bit mounting hole is provided in the face plate plate, and a leading bit mounting hole is provided in the face plate plate. The leading end of the bit is passed through, and the rear end of the leading bit is attached to the back side of the face plate with a pin.
A device for fixing a leading bit in a shield excavator, characterized in that it is detachably fixed.