RING AND DRILLING RIG

TECHNICAL AREA

The present invention relates to a rock drilling machine, such as a top hammer, according to the preamble of claim 1 . THE PRIOR ART

Pressure waves are produced during down-the-hole drilling in the immediate vicinity of the drill bit of a down-the-hole drilling machine. It is namely the case during down-the-hole drilling that the impact mechanism is located at the bottom of the drill string in the drill hole, at the drill bit. The impact mechanism impacts directly on the drill bit.

During top hammer drill ing, a piston moves in a reciprocating motion and impacts on a shan k adapter of a top hammer. Furthermore, rotation is transferred to the shank adapter from a rotary motor. Impact energy and rotation are subsequently transferred from the shank adapter through one or several drill rods and a drill bit to the rock, such that a borehole is created. The rotary motor and the impact mechanism are located at surface level in a top hammer. If the drill bit impacts air instead of rock - known as a idle impact - because, for example, the drill bit encounters a cavity in the rock or because it is necessary to hammer free the threads between the drill rods, a stop ring prevents the shan k adapter from moving forwards too much in the axial direction, and this reduces the risk of damage to the shank adapter. The stop ring is in this way subject to heavy loads.

The drill ing cuttings that are broken loose during rock drilling must be continuously transported away from the borehole. This is carried out with the aid of a flushing medium, for example air or water, which in the front part of a top hammer is led in to the shank adapter through a flush connector and a flush housing . The flushing medium then passes through a passage in the shank adapter and the drill rods and finally passes out through the drill bit to the borehole, whereby the drilling cuttings are flushed out through the space between the drill rods and the edges of the borehole. An example of how this is achieved can be seen in WO2009/148375, where the front part is provided with a sealing cartridge comprising a flush housing, a front guide and a cover plate. This cartridge makes it possible to exchange flush seals without removing the complete front part.

One problem with the rock drilling machine revealed by WO2009/148375 is that also the shank adapter and its stop ring have short lifetimes and need to be changed at regular intervals. Each change of a shank adapter requires the complete front part to be demounted from the rock drilling machine. This means that a number of side bolts must be undone and, most importantly, that the operator needs to lift a relatively heavy load, which the front part with its stop ring, shank adapter, etc. constitutes.

DESCRIPTION OF THE INVENTION

The purpose of the present invention is to achieve a rock drilling machine, such as a top hammer, that solves the problems described above. The rock drilling machine comprises a front part, a removable cartridge arranged in the front part, a shank adapter and a stop ring for the shank adapter. According to the invention, the diameter of the removable cartridge is at least equal to the diameter of the stop ring. This makes it possible during demounting of the removable cartridge to mount or demount the stop ring, without removing the front part from the rock drilling machine. In this way, mounting and demounting can take place more rapidly and more easily, and - not least - with less burden for the operator.

DESCRIPTION OF DRAWINGS The invention will now be described in more detail with the aid of a preferred embodiment and with reference to the attached drawings, of which:

Figure 1 shows a side view of a front part of an assembled rock drilling machine where the stop ring is in the locked condition, Figure 2 shows a side view of a front part of a rock drilling machine according to Figure 1 where a sealing cartridge has been demounted where a stop ring is in its locked condition,

Figure 3 shows a side view of a front part of a rock drilling machine according to Figure 1 where a sealing cartridge and a lock ring have been demounted and where a stop ring is in its open condition,

Figures 4a-b show a front part of a rock drilling machine seen from behind, where a stop ring is in its open condition, and

Figures 5a-b show a front part of a rock drilling machine seen from behind, where a stop ring is in its locked condition.

PREFERRED EMBODIMENT

Figures 1 -3 show a front part 1 a of a rock drilling machine, such as a top hammer, according to the invention. The rock drilling machine is assembled in Figure 1 , while the rock drilling machine is partially demounted in Figures 2 and 3. The drilling machine comprises a housing 1 with, among other features, the front part 1 a. A hammer piston 2 is arranged to carry out reciprocating motion within the housing 1 . The hammer piston 2 acts through impacts against the upper part of a shan k adapter 3. Drill string elements, not shown in the drawings, are connected to the shank adapter 3, as is also a drill bit, also this not shown in the drawings. The shank adapter 3 transfers impact force, together with the force of feeding and rotation to the rock. The term "forwards" will be used in the description below to denote a direction towards the rock, and "backwards" to denote a direction away from the rock.

A stop ring 4 is arranged to protect the shank adapter 3. If the drill bit impacts air instead of rock because, for example, the drill bit encounters a cavity in the rock or because it is necessary to hammer free the threads between the drill rods, the stop ring 4 partially prevents the shank adapter 3 from moving forwards too much in the axial direction, and this reduces the risk of damage.

A cartridge 5 is present in the front part 1 a, for example a sealing cartridge 5, mounted around the shank adapter 3. A cartridge 5 comprises, for example, one or several of the following: a cover plate 6, a guide 7 and a flush housing 8. The exact contents of the cartridge are not relevant. It may be another removable cartridge than a sealing cartridge. The cartridge may also be composed from several parts that can be mounted and demounted individually. What is important is that the cartridge is designed such that the stop ring 4 can be mounted and demounted from the front. Th is takes place in Figures 1 -3 through the cartridge 5 having a diameter that is at least as large as the diameter of the stop ring 4.

The stop ring 4 may be subject to powerful forces from the shank adapter 3. It is, of course, possible to arrange such that the stop ring 4 is resting d irectly against the cartridge 5, but th is is less appropriate, since it would then be possible to cause damage in the cartridge 5.

The stop ring 4 is in Figures 1 -3 arranged instead such that it is mounted such that the stop ring 4 has at least a forwards contact area 9 that makes contact with a stop edge 10 on the front part 1 a. This ensures that the forces to which the stop ring 4 is exposed from the shank adapter 3 are transferred to the front part 1 a and not to the cartridge 5.

Figures 4a-b and 5a-b show an embodiment of how this may be implemented. Figures 4a-b and Figure 3 show the open condition of the stop ring 4 during mounting and demounting of the stop ring 4. Figures 5a-b, Figure 1 and Figure 2 show a locked cond ition of the stop ring 4 during operation of the drilling machine. The front part 1 a is shown from the rear in Figures 4a and 5a. The stop ring 4 is designed as a slightly rounded polygon with three slightly rounded corners. It would be possible to use another number of corners than three, preferably two to five corners. As the number of corners increases, the contact area 9 at the front part 1 a decreases, and the forces to which the stop ring 4 is exposed will therefore be transferred to the front part 1 a in a poorer manner. Also other shapes than polygons work well, but the polygon is a compact and durable shape that also is easy to manufacture, and thus it is for preferred for these reasons. The front part 1 a comprises a recess 12 with a shape that allows the stop ring 4 to be mounted and demounted through the recess 12, Figure 4a. It is preferable that the recess 12 have the same shape as the stop ring 4. A cavity 1 3 for the stop ring 14 has been milled out at the rear end of the recess 12. The cavity 13 is so arranged that the stop ring 4 can lie in a locked condition or in an open condition. When the stop ring 4 has been inserted into the cavity 13, the stop ring 4 can be rotated - through 60° in the example that has three corners - from the open condition to the locked condition, such that the contact area 9 of the stop ring will be in contact with the stop edge 10 in the locked condition, Figure 5a.

The drilling machine vibrates during drilling and there is therefore a serious risk that it would be possible in this way for the stop ring 4 to rotate itself back to the open condition. Since this is not desirable, it is appropriate that the stop ring 4 be provided with a lock device, for example a lock ring 14.

The lock ring 14 has a similar shape to that of the stop ring 4 and the recess 12, and it is therefore possible to mount also the lock ring through the recess 1 2. Furthermore, the lock ring 14 comprises lock cams 15 that pass between the stop ring 4 and the front part 1 a when the stop ring 4 is in its locked condition. When the stop ring 4 has been rotated in place to the locked cond ition as described above, the lock ring 14 is mounted such that the lock cams 15 enter into the compartment between the stop ring 4 and the front part 1 a. This makes it impossible that the stop ring 4 be rotated back to its open condition. Since the cavity 1 3 has been constructed such that the stop ring 4 can be rotated only between an open condition and a locked condition, the stop ring 4 cannot be rotated in any other direction.

The lock ring 14 has approximately the same length as the recess 12, and when the cartridge 5 is mounted in its place in the front part 1 a the lock ring 14 will therefore be held in place by the cartridge 5. It is, however, preferable that the tolerance be such that the length of the lock ring 14 is somewhat less than the length of the recess 12. This to ensure that the forces to which the stop ring 4 is exposed shall primarily be transferred to the front part 1 a through the contact area 9 and not be transferred to the lock ring 14 and onwards to the cartridge 5 to too high a degree. The cartridge 5 is mounted at the front part 1 a in Figures 1 -3 by means of screws. If the cartridge 5 is designed so that it is instead pressed in and, for example, locked in place by a cover plate, it would be possible to integrate also the lock ring 14 in the cartridge 5, even if the mounting will be somewhat easier if this is kept separate.

At least one of the lock ring 1 4 and the stop ring 4 can be provided with demounting means 16, 17 in order to make demounting easier. The lock ring 14 is provided in Figures 1 -5 with two screw holes 16. Two long screws can be deployed in the screw holes 16 during demounting, and it will thus be easy to pull the lock ring 14 free. The stop ring 4 is provided with similar screw holes 17, see Figure 3. It is possible again to rotate the stop ring 4 after the lock ring 14 has been demounted. The two long screws can then be deployed instead in the screw holes 17 of the stop ring, whereby the stop ring 4 can be rotated to its open condition and then withdrawn. The stop ring 4 can in this way be mounted and demounted, without it being necessary to remove the complete front part 1 a, with all of its weight.

The invention is, naturally, not limited to the example described above: it can be modified within the scope of the attached patent claims. The present invention, for example, refers to all rock drilling machines that comprise piston means that impact upon a shank adapter, i.e. all rock drilling machines in which pressure waves are produced not in the immediate vicinity of the drill bit. The present invention refers, for example, to, but is not restricted to, a top hammer.