Field of invention

The present invention relates to a rock drill for percussive drilling, although not exclusively, especially to rock drill for top hammer or DTH drilling having a modified flushing hole for improved readability of an identification marker.

Background art

Percussion drill bits are widely used both for drilling relatively shallow bores in hard rock and for creating deep boreholes wherein a drill string is employed. In 'top hammer drilling' a terrestrial machine is operative to transfer a combined impact and rotary drive motion to an upper end of the drill string. Whilst a drill bit which has a plurality of inserts or buttons, made from a hard material, mounted on its front face is positioned at the lower end is operative to crush the rock and form the boreholes. The cuttings resulting from the rock breaking action need to be removed so that the next impact will hit solid rock again and therefore break the new rock more efficiently than if the cuttings were still present.

Therefore, a flushing media, such as water, is supplied from the drill string to the front face of the drill bit through flushing holes via a central flushing channel and returned through an annual space formed between the drill string and the hole. In down-the-hole (DTH) drilling the impact device is in the drill hole.

It is desirable to be able to identify rock bits, in terms of serial number to be able to recall the properties of the bit. It is further desirable to be able to track drilling parameters from specific drill bits for process improvement purposes. The current method of identifying drill string component is to attach a label with the product information on. The problem with this is that it easily comes detached during the drilling operation. Therefore, the problem to be solved is how to be able to identify drill string components in a way that will survive the steel wash and harsh drilling environment. Summary of the Invention

It is an objective of the present invention to provide a rock drill bit for percussive drilling comprising: a bit head having a front face provided with a plurality of buttons; a shank that projects rearwardly from the bit head centred on an elongate bit central axis having a top end that is proximal the bit head and bottom end that is distal the bit head; an internal cavity extending through the shank; a central flushing channel extending from the top end of the cavity wherein the central flushing channel has an endmost surface; at least one flushing port having a peripheral wall defining its diameter extending from the endmost surface of the central flushing channel through the bit head for delivering flushing media to the front face via a flushing hole; characterized in that: at least one of the flushing port(s) has at least one indentation in its peripheral wall and wherein there is an identification marker positioned in the indentation.

Advantageously, this provides a drill bit having an internal surface where an identification marker can be placed which is protected from steel wash and the harsh environment surroundings during the drilling operation, therefore reducing the risk that the identification marker is damaged and is therefore still readable after the drilling operation, whilst also being able to be positioned in a location that is readable, for example by using a smartphone app.

In one embodiment, the flushing port has a diameter Di and the indentation has a diameter D2 and wherein D2 < Di / 2. In another embodiment, D2 is at least as larger as the identification marker. If the size of the indentation is too small, it will not be large enough to accommodate the identification maker. If the size of the indentation is too large it will compromise the structural integrity of the drill bit. There could either just be one indentation to keep manufacturing costs down or there could be multiple indentations to enable more than one identification tag to be accommodated for increased reliability.

In one embodiment, the indentation has a depth of between 2 - 40 mm. If the depth is too deep this adds unnecessary manufacturing costs and makes the identification marker more difficult to read. If the depth is not great enough the identification marker is not as well protected.

In one embodiment, the angle of a side wall on the indentation is between -10 to 20° relative to the central axis. Advantageously, this angle range provides optimized readability of the identification marker from the exterior of the drill bit.

In one embodiment, the angle of a base of the indentation is between 70 to 120° relative to the central axis. Advantageously, this angle range provides optimized readability of the identification marker from the exterior of the drill bit.

In one embodiment, there is a line of sight between base of the indentation and a reader located external to the drill bit and wherein the identification marker is located in the line of sight. Advantageously, this enables the identification marker to be read for the exterior of the drill bit.

In one embodiment, the indentation is located on the radially outer wall of the flushing port. Advantageously, this provides optimized readability of the identification marker from the exterior of the drill bit.

In one embodiment, the indentation a milled indentation. Advantageously, this is the simplest manufacturing method.

In one embodiment, the identification marker is a radio frequency identification (RFID) tag.

In another embodiment, the identification marker is encoded with one-dimensional or two- dimensional optical machine- readable code. Advantageously, by arranging the first identification marker as a one-dimensional or two-dimensional optical machine-readable code, the first identification marker can be arranged where it is covered by metal surfaces without affecting the readability of it. In one embodiment, the identification marker is a Quick Response (QR) code, a High Capacity Coloured Two Dimensional Code, a European Article Number code, a DataMatrix code, or a MaxiCode. Preferably, the identification marker is a DataMatrix code. A data matrix code is a two-dimensional bar code which may be in the form of a square or rectangular symbol made up of individual modules of predetermined size in the form of dots or squares. The individual modules form an ordered grid of contrasting (e.g. dark or light) modules, bordered by a finder pattern used to specify the orientation and structure of the symbol. The identification tag can in this case be used to store information about a very large amount of individual sintered bodies, depending on the size of the data matrix code. The size may typically be 12x12 modules, or larger depending on needs. In an error correction algorithm, several damaged or blurred modules can be corrected for. Advantageously if a data matrix code is used more information can be stored in a smaller area. Further, only approximately 32-72% of the data matrix code needs to be intact in order for the information to be read, therefore even if the data matrix code is slightly damaged the information can still be read. It may be preferable that the ID tag used has an industry standard associated with it.

In one embodiment, the identification marker is etched, engraved, impressed, imprinted, or painted on. Advantageously, by having the identification marker etched, engraved, impressed, imprinted, or painted to the first coupling part there is no need of any special marker holding units which would require a special design of the processing tool body in order to make room for such a marker holding unit. A further benefit of not requiring a special marker holding unit is that the risk of unbalances in the processing tool body can be reduced. Preferably the identification marker is laser engraved onto the base of the indentation. Advantageously, the location can be reached most easily using a laser.

A specific implementation of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

Figure l is a longitudinal cross section of a rock drill bit. Figure 2 is a top view of a rock drill bit.

Detailed

Figure 1 shows a longitudinal cross section of the rock drill bit 2 for top hammer drilling having a bit head 4 configured to be attached at one end of a drilling assembly (not shown). The bit head 4 has a front face 6, with a plurality of buttons (not shown), otherwise referred to as inserts or cutters, mounted on. The buttons are made of a hard material, such as cemented carbide and are usually uniformly distributed across the front face 6. The buttons engage with the material, such as rock, to be crushed during the drilling operation. The bit head 4 is centred on an elongate bit central axis 12.

The rock drill 2 also has a shank 10 that projects rearwardly from the bit head 4. The shank 10 is also centred on the elongate bit central axis 12 and has a top end 14 that is proximal to the bit head 4 and a bottom end 16 that is distal to the bit head 4, the shank 10 is hollowed out such that a cavity 18 (or bore) is formed inside. The cavity 18 extends from the bottom end 16 of the shank to a longitudinal internal surface 20 at the top end 14 of the shank 14. Flushing fluid, which is normally water for top hammer drilling, but could be air or any other fluid suitable for flushing, is transported from the bottom end 16 to the top end 14 of the cavity 18. Both the bit head 4 and the shank 10 are typically made from steel.

The top end 14 of the cavity 18 connects to a central flushing channel 22, which is centred around the bit central axis 12 of the shank 10, into which the flushing media is directed. The central flushing channel 22 has an endmost surface 26 at its top end 14 from which one or more flushing port(s) 24 (otherwise known as flushing passages) extend from through bit head 4 to the front face 6 terminating at a flushing hole 28 positioned on the front face 6.

The flushing port(s) 24 extend from the central flushing channel 22 at an angle that is not parallel to the longitudinal axis 12, such that they extend radially outward from the central flushing channel 22. Each flushing port 24 has a peripheral wall 30, which defines its diameter, Di. At least one of the flushing port(s) has an indentation 32 positioned on the peripheral wall 30. The indentation 32 has a diameter, D2.

Figure 2 shows a top view of the rock drill bit 2, whereby it can be seen that an identification marker 34 is positioned on the indentation 32 such that is visible from above through the flushing hole 28 and therefore readable, for example by using a smartphone app. In figure 2 the indentation 32 has a cylindrical shape however when viewed from above appears as a crescent shape. The indentation could however be any other suitable shape.

In one embodiment, D2 < Di / 2.

In one embodiment, the indentation 32 has a depth of between 2 - 40 mm, preferably between 5-30 mm, more preferably between 7-25mm.

In one embodiment, the angle of the indentation 32 is between -10 to 20° relative to the central axis 12, preferably, -5 to 10°.

In one embodiment, the angle of a base 38 of the indentation 32 is between 7 to 120° relative to the central axis 12. Preferably between 80 to 100°.

In one embodiment, is a line of sight 40 between the base 38 of the indentation 32 and a reader 42 located external to the drill bit 2 and wherein the identification marker 34 is located in the line of sight 40. In other words, the identification marker 34 is visible and / or readable from the outside the rock drill bit 2.

The rock drill bit 2 according to any of the previous claims wherein the indentation is located on the radially outer wall 44 of the flushing port 24.

In one embodiment, the indentation 32 is a milled indentation, which was formed by milling. In one embodiment, the indentation 32 is a drilled indentation, which was formed by drilling using e.g. a flat drill. In other embodiments, the indentation may be formed by any other suitable method. In one embodiment, the identification marker 34 is a radio frequency identification (RFID) tag.

In another embodiment, the identification marker 34 comprises identification data encoded in a one-dimensional or two-dimensional optical machine-readable code.

According to one embodiment, the identification marker 34 is etched, engraved, impressed, imprinted or painted on the indentation 32. A particularly suitable way of arranging the identification marker 34 by laser engraving.

EXAMPLE 1

Drill bit 77385348 A-R48 with diameter of 48 mm with an identification markers positioned on an indentation of the flushing port were tested in a mine in Tampere in wet underground conditions to end of bit life, 392 drill meters, the identification marker was readable with Datalogic220 reader and lens after drilling.