EP0784731A1

EP0784731A1 - A drilling apparatus and method to drill a hole in different kinds of soil

Info

Publication number: EP0784731A1
Application number: EP95934147A
Authority: EP
Inventors: Valto Ilomaki
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-10-05
Filing date: 1995-10-05
Publication date: 1997-07-23
Also published as: FI944640A; FI944640A0; KR970706442A; WO1996011323A1; FI103430B1; FI103430B

Abstract

A method and drilling apparatus to make a hole or tunnel in different types of soil, such as rock or clay, using one and the same drill bit or a bit assembly (2, 3), (9, 10). By means of the conical design of the bit soft soil is forced to the sides of the hole that is being drilled and, by means of drilling elements (5) on the front face of the bit, encountered stones, rock etc. are crushed into drill waste removable mainly through the bit backward.

Description

A DRILLING APPARATUS AND METHOD TO DRILL A HOLE IN DIFFERENT KINDS

OF SOIL.

This invention relates to a drilling apparatus by means of which a hole is drilled into rock or stony soil and soft clay. While drilling the hole, soft soil is forced aside and rock and stones are drilled away.

Previously known are different types of arbors, which are forced into the ground by means of an arbor spindle. While advancing the arbor pushes soil toward the hole sides. Generally, the arbor is replaced by a tube which is pushed in place of the arbor and left in the hole. Such an arbor advances by force only in favourable soil.

Holes have been made in soft soil also by drilling, for instance by rotation of a wing bit or a screw bit, through which or con¬ veyed by which soil has been easily conveyed backwards as a huge flow of mass and removed from the hole.

The above mentioned drilling devices are applicable means to make holes in a certain type of soil and it is hardly possible to make holes with them in any other type of soil.

Surprisingly, a drilling apparatus and a method according to this invention are well adapted to all possible sorts of soil and the invention is characterized in what is presented in the patent claims.

The most significant advantage of this invention can be con¬ sidered the possibility to make a hole into all possible types of soil with one and the same drill bit. It is not necessary to examine the quality of soil nor to change drilling apparatus or drill bit when the soil type changes. When the bit is hammering and rotating and fitted with working means, it can drill rock and stones. Further, thanks to the conical design of the drill bit loosened soil is forced to the sides of the bit in soft ground, whereat it needs not to be removed from the hole. This procedure works automatically while the bit is advancing. Usually, drilling into soft soil forwards rapidly and produces much removable soil. Since loosend soil is forced mainly aside from the hole, there is hardly any loose soil to be removed. The drilling goes on uninter- tedly without any delays due replacements of the drill bit, which makes the use of this kind of general-purpose drilling apparatus most advantageous.

In the following the invention is disclosed with reference to the enclosed drawing, where

Fig. 1 is a section of the drill bit in a drilling apparatus.

Fig. 2 is the bit viewed from the front.

Fig. 3 is a section of the drill bit in another drilling apparatus. Fig. 4 is the bit viewed from the front. Fig. 5 is a section of line B - B of the bit.

Figure 1 shows the drill head of the drilling apparatus with a hammering machine 1 that strikes a bit assembly 2,3. The hammering machine also rotates the bit assembly. The bit assembly has an inner bit 2 and around it a ring bit 3. The inner bit 2 can be pulled out from the bore while drilling. By means of a joint allowing a small longitudinal motion, the outer ring bit 3 rests on protective tube 4 pulling it into the hole while drilling.

Pressure medium, mostly compressed air, flows from the hammering machine along channel 8 through the bit to the front side of the bit. This air is guided back through the bit along channels 6, whereby the air flow conveys drill waste along with it. On drilling rock, buttons 5 fixed to the bit are striking the rock and loosening chips from it, which form the drill waste that is conveyed by means of the air to the rear side of the bit and out from the hole. On drilling soft soil, clay for instance, the drill waste is conveyed only partly through channels 6 but is forced due to the conical bit, to the sides of the hole, becoming partly even more compact. Since the bit is both hammering and rotating, loosend soil is easily driven to the sides of the hole.

On hitting a big stone or rock while drilling in soft ground, the forcing of soft soil aside stops and the bit starts to drill the stone by hammering and the compressed air removes it along channels 6.

Figure 2 is the front side of the bit, where channels 7 and 8 are also visible.

Figure 3 shows another embodiment of the the bit assembly, where the conical angle OCis smaller, less than 90°' and where there are channels 12 from each step surface. For bit buttons 5 the front face must be in the forward direction and not deviate very much from the face perpendicular to the drilling direction. The bit buttons won't stand hitting rock slantingly. Even the stepped conical form is well adaptable to force soft soil aside.

Figures 4 and 5 show more accurately the position of channels running through the bit. Further, on the bit surface grooves 14 are cut directed away from the centre. On drilling soft soil, the purpose of these grooves is to grind soil in front of the bit while the bit is rotating and so the soil becomes more loose. Loose soil moves more easily from the front of bit to the sides. On the other hand, the openings throuhg the bit are so small that while advancing very fast into soft soil, the loosened soil cannot exit through holes 12 but is easily pushed to the sides.

The conical angle of the bit can also be less than 70°. The cone must not have the same number of degrees all over the bit but the conical shape can vary step-by-step starting from the bit point.

Claims

PATENT CLAIMS

1. A method to drill a hole or a tunnel into different types of soil, such as rock, stony ground or clay, using one and the same hammering and rotating drill bit or a bit assembly (2,3), (9,10), characterized in that by means of the conical design of the drill bit soft soil is forced to the sides of the hole that is being drilled and encountered stones and rock etc. are crushed by drilling means in the front face of the bit into drill waste removable backward through the bit.

2. A method according to patent claim 1 characterized in that scavenging agent is led to the front side of drill bit or bit assembly to force loosened soil aside while drilling.

3. A drilling apparatus for making a hole or tunnel in different types of soil, such as rock, stony ground or clay, using one and the same hammering and rotating drill bit or a bit assembly (2,3), (9,10) characterized in that the drill bit is conical towards the its point, the angle of bit point under 90°, the front face of bit having working means (5) and that there are scavenging channels (6), (12,13) backward through the bit.

4. A drilling apparatus according to patent claim 3 characterized in that the drill bit is a stepped cone having planar faces for working means (5) .

5. A drilling apparatus according to patent claim 3 characterized in that there are scavenging channels (12,13) (6) from the planar faces (5) backward through the drill bit.

6. A drilling apparatus according to any of the patent claims 3 - 5 characterized in that there are grooves (14) backward on the bit surface.

6. A drilling apparatus according to any of the patent claims 3 - 6 characterized in that the cone angle of bit is under 70°.