The invention relates to a drilling apparatus for drilling a hole into the ground/rock, whereby a protective pipe is placed, in connection with drilling, in the drilled hole on the required portion, most commonly on the portion of ground drilling, at least, which is either left in the hole as a protective pipe or as a pile pipe, or is withdrawn later on.

As an installation method of protective pipes and drilling pile pipes installed in the drilled hole, it is previously known to pull them into the drill hole so that a pull shoulder on a drill bit unit pulls the protective pipe or pile pipe by a drill shoe fixed on the pull shoulder. A drill shoe is circular and, in a drilling situation, it is locked in the axial direction to a groove formed by the pull shoulder and the central reamer, reamer pieces, or eccentric reamer. The drill shoe is loosely placed in said groove so that it may rotate in relation to the drill bit unit.

In known solutions, a pulled protective or pile pipe is welded by its front part to the drill shoe.

The solution described in the above has the drawback, at least as regards drilling pile pipes, that if the drill pile pipe is left in the hole, the drill shoe needs to be left in the hole, too. When the subsequent pile pipe or protective pipe is drilled, a drill shoe must first be installed in the drill bit unit. This causes the need to acquire a new drill shoe, its installation, as well as welding at every pile pipe. These create considerable material costs and additional work for the drilling operation.

To eliminate the above drawbacks, a new installation apparatus for the protective/pile pipe has been developed, by means of which said pipe moves, in connection with drilling, into the hole without fixing said pipe to a drill shoe or any other structure. The drilling apparatus according to the invention is characterised in that in order to install a protective/pile pipe into a hole, the drilling apparatus includes a pull means installed within said protective/pile pipe, which a drill bit unit of the drilling apparatus is arranged to pull into the hole during drilling, and the rear end of said pull means includes an addition part increasing the outer di- ameter of the pull means, or a part transferring the pulling force of the pull means to the rear edge of the protective/pile pipe, arranged to push the protective/pile pipe to the hole being drilled. The benefit of the inventive drilling apparatus is that in pile drilling there is no need to fix the pile pipe to the drill shoe, but it is enough that it is installed over of the inventive pull means per se. When the pull means is fixed to the drill bit unit and there is an external shoulder at the rear end of the pull means having a suita- ble length, the pull means advancing with hammer strokes along with drilling pushes the protective/pile pipe into the hole with its shoulder. In pile driving, numerous pile pipes with equal lengths are usually installed in the ground, one pull means of the correct length allows the pushing of pile pipes into holes during drilling even without welding and by using one pull means. When the length of the pile pipes differ, the length of the pull means may correspondingly be changed in various ways, whereby the mutual lengths of these pipes may be set close enough to each other.

By using the same invention, it is also possible to drill a so-called rock bond as an "extension" to the protective pipe or pile pipe, that is, a pipeless portion in the rock for a desired distance by releasing the addition part, ring, or pushing means placed at the rear end pushing the protective /pile pipe, after which drilling is continued for the desired bonding length without the protective/pile pipe being pushed in the hole.

In the following, the invention will be described in greater detail with reference to the attached drawings, in which

Figure 1 is a sectional side view of a drilling device.

Figure 2 is a sectional side view of the inventive inner pipe acting as a pull means.

Figure 3 shows the inner pipe and a protective pipe over it.

Figure 4 shows an extension joint of the inner pipe. Figure 5 shows a drilling device that has pull members, such as rods, as the pull means,

Figure 1 shows a structure fixed to a drilling device meant for drilling ground or rock, in which a protective/pile pipe 5 to be left in the ground is not pulled into a hole by means of strikes the drill unit is subjected to, but the pushing and strikes are targeted at the rear end of the protective/pile pipe. The drill unit comprises a drill bit body 1, drill bits 2, and drill boom 3.

The drilling device of Figure 1 comprises, at the tip, turnable drill bits 2 arranged to the drill bit body 1, which during withdrawal of the drill bit unit from a hole turn inward so that the entire drill unit 1 - 3 may be pulled back from within the pipe 5 that is left in the ground. In the inventive solution put forth in Figure 1, the drill unit 1 - 3 pulls with it into the hole the inner pipe 4 acting as the pull means, the inner pipe being fixed to the drill unit at its front end in a manner known per se. The drill unit 1-3 and its drill bits 2, in particular, make room for the protec- tive/pile pipe 5, in other words it forms the drilled hole for the protective/pile pipe 5.

The drill unit 1 - 3 includes a ring shoulder 7 by means of which a ring 8 at the front part of the inner pipe 4 on the inner surface of the inner pipe 4 is locked in the axial direction to stay on the front side of said shoulder 7. The ring 8 is fixed to the inner pipe 4 as a welded ring part, for example, either as a mere ring on the inner surface of the inner pipe 4, as shown in Figure 2, or welded as a ring-like bulge at the end of the inner pipe 4, as shown in Figure 3. In every case, the ring 8, or similar, conveying strikes or force to the inner pipe is arranged as rotating mutually freely with the drill unit 1 - 3. The drill unit 1 - 3 is struck forward by hammer strikes that the drill boom 3 is subjected to. These strikes are conveyed to the inner pipe 4 by means of the shoulder 7 and ring 8, whereby the inner pipe advances with the drill unit 1 - 3. In some cases, the advancing of the drill unit may be implemented by pushing instead of the strikes. The rotating of the drill unit, however, takes place in all the drill types. When a hammer strike is targeted on the drill unit 1 - 3, the force of this strike is directed to the drill unit 1 - 3 inside the protective/pile pipe 5 at its front end. From there, the force of the strike is conveyed to the rear end of the protective/pile pipe 5.

Figure 1 also shows the option to drill the rock bond portion at the final part of the hole, into which portion there will be no pipe 5. The inner surface 13 of the pipe becomes the bonding surface. The front edge of the pile pipe 5 is then left at position S. The advancing of the protective/pile pipe 5 is stopped by removing the addition part 6, ring 9, or hooks 14 from the pull means 4, 15. Figure 2 shows a transferrable addition part 9 on the surface of the inner pipe 4, the position of which on the surface of the inner pipe is adjustable according to the length of the protective pipe 5 and lockable in the selected position by, for example, welding or by a bolted joint when the inner pipe comprises mounting holes. This solution considerably reduces the number of required inner pipes 4.

Figure 3 shows an adjuster sleeve 10 arranged over the inner pipe 4, by means of which the front edges of the inner pipe 4 and the protective pipe 5 may be adjusted into the correct place at the drill body 1. At the ends of the adjuster pipe 10, there are flange parts 11 that convey the pushing force. By using an adjuster pipe 10, welding is avoided. Adjuster pipes 10 are required in different lengths.

Figure 4 shows how the inner pipe 4 may be formed as extended by the use of a threaded joint 12. As an extension to the inner pipe 4a, a pipe 4b may be screwed, or a pipe provided with a thread 12 at both ends and having a suitable length may be screwed between the pipes 4a and 4b. Figure 5 shows, as an alternative pull means, two or more pull means 15 fixed to the drill shoe 8 at their ends by bolts or welding, for example, such as rods that have hooks 14 at their rear ends, which extend to the back of the back edge of the protective/pile pipe 5 being pulled, and which transfer the pulling forces received through the rods 15 into forces that push the protective/pile pipe 5. Instead of the pull rods, wires and chains may be used as corresponding pull means 15. It is easy to make extension joints to such rods, wires, and chains according to how long a protective/pile pipe is at any one time placed in the drilled hole.

The power transfer of the pull means 4, 15 to the rear end of the protective/pile pipe 5 may be cut/removed by, for example, detaching the addition part 6, 9 or the conveying part 14 shown in Figure 5, whereby the protective/pile pipe 5 may be left in place to form a rock bond when drilling is continued. The addition part 6, 9, 14 has a mating surface that conveys the pushing and/or strikes to the end surface of the protective/pile pipe 5. Such an addition part need not be a ring of the size of the rear edge of the protective pipe 5. Smaller contact surfaces, such as hooks 14, are able to convey force or strikes to the protective pipe 5.