DE2512785B2 - DRILLING CHISEL FOR DEEP HOLE HAMMER - Google Patents

Description

The present invention relates to a drill bit for downhole hammers, with one facing the attack surface widening drill bit with flushing bores, recesses and hard metal inserts, in particular X-cutting, ribs, warts or the like. Is provided, and with an outer longitudinal grooves having a reduced cross-section compared to the drill bit, wherein the drill bit is designed as a wear shoe and is interchangeably connected to the shaft

Downhole hammers for deep drilling are inserted into the borehole and immediately in front of the bottom of the borehole beating and possibly rotating driven. For this purpose, high-pressure drives with large Compressed air performances used. Suitable devices are for example in DT-PS 10 00310, 1035075 and 14 08 666. The usual drilling rigs have mobile mounts, if necessary with a rotary drive, and use pistons whose impact energy is transferred directly to the drill bit. This is usually a downwardly conically thickening hollow part with outlet openings for cooling the too as a drill bit designated tool and for flushing the cuttings along the outer longitudinal grooves of the drill bit as well as the connecting rods reach the top and are sucked off above ground can.

The heavily used drill bits not only occur when working in very hard and abrasive or fissured rock shows an extraordinarily large amount of wear, which leads to the fact that after relatively drill bits with diamond or carbide inserts have to be changed for a short service life of various kinds are provided, for example with rolls, X or cross cutting edges, warts, etc. For this purpose, pulling the drill string out of the borehole and then reintroducing it is fio necessary so that an interruption in drilling progress is inevitable.

It has already proposed drill bits whose lower part is designed as a wear shoe and with the Shank is interchangeably connected, e.g. B. by means of a screw thread (DT-OS 15 33 631) or by means of a Wedge connection (DT-GM 19 22 505). In rough practice, however, it has been shown that these are rigid Fixings do not withstand the forces acting for long. Especially when the impact work with High frequencies going on, the connection between the bit shank and drill bit is made in a short amount of time hopelessly destroyed

The object of the invention is to provide a drill bit while avoiding the disadvantages of the prior art create that can withstand high loads over long periods and do it with simple economic means makes it possible to keep the downtime short and the costs of the bit change low.

In a drill bit of the type mentioned, the invention provides that the wear shoe is elastically buffered connected to the shaft Reaction forces are not transferred, as is conventionally done, by a rigid tool with a hard impact on the hammer and back onto the rock, which caused repeated bouncing with corresponding tool stress. Rather, such vibrations are dampened or suppressed by the buffering without any significant impact energy being consumed. This protects tools and rods. When consumption has occurred, the buffered wear shoe can be replaced quickly and easily in a simple device _; while the intermediate anvil has to be replaced later thanks to its much longer service life. Usually, however, with considerable expenditure of time and effort, either the used drill bit had to be removed from the rod assembly and a new bit screwed on, or the wear shoe had to be detached from the forcibly deformed or destroyed connection with great effort.

One embodiment of the invention consists in that between the shaft end and an inner end face of the wear shoe a buffer piece sits under tension, in particular a cylindrical block z. B. off Polyurethane, special rubber or the like with cder without spring load. Such buffer pieces are in the Production is inexpensive, easy to assemble and extremely advantageous in operation. Tests have shown that the service life of prestressed buffer pieces is very long and that of the wear shoe at least achieved.

A further development of the invention provides that the buffer piece and wear shoe from a central bore are at least partially interspersed. This makes it possible to apply the flushing agent directly to the bottom of the borehole approach, which leads to a noticeable increase in drilling progress. The central hole can end in the wear shoe near the face of the latter as a blind hole and radially through z. B. three be continued at regular central angles extending inclined bores, which are preferably on longitudinal outer grooves of the wear shoe open. Correspondingly, a central bore in the shaft can be approximately in be formed its longitudinal center ending blind hole, which merges into oblique bores on the outer longitudinal grooves of the shaft open, which preferably taper towards the center of the shaft. These measures assist in guiding the flushing agent through the drill bit and together on its outside with the cuttings up.

To connect the shaft and wear shoe with the buffer piece located in between, according to a Further specialization of the invention provided that the shaft near its lower end at least two has diametrically opposed approaches behind which fastening bolts engage positively, which sit in cross holes of the wear shoe and can be secured by longitudinal pins. Such Connection can be established as quickly as it can be released. The longitudinal pins can be provided with tapered ends and in turn be secured by cross pins, so that inadvertent loosening or loosening of the Connection is excluded. Because the buffer piece sits under tension in the wear shoe, a static permanent force is exerted on the connecting bolts, which reduces the impact load and thus counteracts permanent deformation of the connecting elements. It is also possible and According to the invention, at least the longitudinal pins are designed to be conical and correspondingly conical To keep cross bores secured until transfer these connecting elements to replace the wear shoe be solved, which is particularly easy and quick in this embodiment.

The buffer piece is preferably in a round chamber of the wear shoe arranged, the side wall of which is undercut, concave or with at least one annular groove is provided. Thanks to such a shape, this is done by means of a suitable device Once introduced into the wear shoe buffer piece held therein in a form-fitting manner, and also there is space available so that the material of the buffer piece can evade if at the moment the Axial compression takes place with a hammer blow

The invention also provides that the buffer piece at least two cohesively connected parts of different density and / or elasticity has in particular a harder core that is on all sides is enclosed in a softer jacket, it is particularly useful if the buffer piece at least has a closed-cell foam part and at least one convexly curved and / or on the circumference Chamfered end face has while the buffer piece in the simplest case a substantially cylindrical If a flat ring is, it can preferably have bulges on both end faces that dampen movement to serve. Its central bore can, for example, be arched in the shape of a barrel, so that in the state strongest axial compression nor a cylindrical through hole is present A multilayer Construction helps to optimize the service life of the buffer piece despite high alternating loads to hold long. Expediently, a flatter stop disk adjoins the J-buffer piece radially, which the shaft of the drill bit in its end position lowers

According to the invention, the shaft and the wear shoe can be detachable by means of a bayonet fastening be connected so that the replacement is quick and easy to do, but one in operation Sufficient strength of the connection is guaranteed in particular when the rotating drive of the Drill bit a tightening of the bayonat fastening takes place continuously

. Furthermore, the shaft according to the invention can have an annular groove into which a wear shoe arranged, preferably split retaining ring engages, which takes over the function of the above-mentioned longitudinal and transverse pins.

To secure the drill bit, it is advantageous if its shank for mounting the drill bit from above in a retaining cap can be inserted, which has an annular shoulder or similar stop parts at the bottom which a counter shoulder of the shaft is axially supported.

Another advantageous embodiment of the invention is that the shaft and wear shoe have a polygonal profile have, in particular disharmonious PC4 profile, so that with free axial mobility a positive entrainment is ensured in the direction of rotation

Yet another feature of the invention provides that the wear shoe has at least one insert contains, the outer part of which is set off on the circumference and padded in the circumferential direction with damping inserts This ensures sufficient damping even in rough operation.

According to a particularly simple embodiment of the invention, the stop disc is with the Wear shoe formed in one piece and the buffer piece held sunk therein.

To attach the wear shoe is provided according to another embodiment of the invention that there is a threaded ring axially securing the retaining ring on the drill bit shaft, which is specifically for the plant has a collar preferably provided with wrench surfaces on a shoulder of the wear shoe. This ensures that the free rotation of the driver ring is not hindered. Also results thread relief and a particularly large support surface.

An important measure provides for a drill bit according to the invention that the wear shoe is designed in two parts, an upper ring part with a lower sole part by secured fastening elements is releasably connected, e.g. by means of Allen screws with force-locking or form-locking locking. This simplifies the attachment and under certain circumstances enables an even cheaper replacement, when the sole part is used up The ring part can reach over the retaining ring and on the sole part Have resting support parts, so that a good power transmission is guaranteed for the rotating An embodiment is advantageous in which the sole part is interlocked with the ring part, preferably by means of alternating steps on the inner and / or outer circumference. These levels can be in in the same direction or in the same direction of rotation flat or wedge-like as the lugs or shoulders Use and wear shoe. The steps ^ are preferably designed identically and with regular angular <"Circumferential distances arranged

Yet another feature of the invention provides that the upper and the wear shoe are different
Consist of material, e.g.
Impact resistance on the one hand and off

abrasion-resistant alloy, such as X155Cr \

on the other hand. Such a material pairing has
Advantage that the full force of the booklet
can be transferred and yet very much
Service life for the drill bit can be achieved " i service life can still increase significantly" 15 if, according to the invention, at least Tfeujy drill bits are hard-borated, whereby an ob "
layer of z. B. ϋβ to 0.4 mm yeast a VIc
nn area above about 1800 HV

to

Further details of the invention emerge from the following description of exemplary embodiments based on the drawing. In it shows

F i g. 1 shows an exploded side view of a drill bit according to the invention consisting of a shaft, buffer piece and wear shoe;

F i g. FIG. 2 is an exploded sectional view of FIG Components of a drill bit according to the invention, with sections corresponding to the lines H-H in FIG. 5 and 7,

3 is rotated by 90 ° with respect to FIG. 1 Side view of the wear shoe according to the invention,

F i g. 4 shows an axial sectional view of the wear shoe along line IV-IV in FIG. 6,

F i g. 5 shows a cross section through the wear shoe according to the line V-V in FIG. 3, '5

F i g. 6 shows a bottom view of the wear shoe from FIG. 3,

F i g. 7 shows a bottom view of the shank of a drill bit according to FIG. 1,

F i g. 8 corresponds to a cross section through the shaft corresponding to the line VIII-VIH in F i g. 1.

F i g. 9 shows a longitudinal section through the shaft along the line IX-IX in FIG. 8th,

F i g. 10 shows an axial section through a drill bit according to the invention,

F i g. 11 shows a cross section according to the line XI-XI in Fig. 10,

F i g. 12 shows an axial section through another embodiment of a drill bit according to the invention along the line XII-XII in FIG. 13 and

FIG. 13 shows a cross section along the line XIII-XHI in FIG. 12.

An inventive drill bit 1 consists of a shank 2, a buffer piece 9 and one as Wear shoe 14 trained drill bit, which is interchangeably connected to the shaft 2 For the sake of clarity, these components are shown in FIG. 1 and 2 shown exploded

The shaft 2 has outside longitudinal grooves 3, which extend approximately from the axial center of the shaft 2 to its upper or Anvil end 8 is enough. A extends from the lower end 6 to approximately the longitudinal center of the shaft 2 Central bore 4, which forks near its end in inclined bores 5 which open into the outer longitudinal grooves 3. Near the lower end 6 has the Shank 2 lateral projections in the form of lugs 7, with which it can be fastened in the wear shoe 14 Drawn embodiment, two such approaches are provided diametrically opposite one another, but a larger number of projections with peripheral and axial offset can also be provided.

The buffer piece 9 preferably consists of a harder core 10, which is surrounded by a softer jacket 11 It is cohesively enclosed It has an axial through opening or central bore 12 which, in contrast to the illustrated embodiment (Fig. 1 and 2) can be roughly barrel-shaped so that they only assumes a substantially cylindrical shape when axially pressed on one end face 13 or on both The end faces can be curved, the buffer piece 9, where * ° the curvature can also be designed so that on the inner and / or on the outer edge a cylindrical Section exists

The wear shoe 14 has a shape that is slightly conically thickened towards the bottom. Towards the bottom or ^6s to the sole or outer end face 15, the wear shoe 14 is chamfered on its outer circumference. Inserts introduced in the drawn execution example as approximately hemispherical warts 21 are ausgebil det. In the circumferential direction, the round shape is de Wear shoe 14 on the outside by longitudinal grooves 2 (pierced, which from the bottom 15 to the Außenwam lead up. These longitudinal grooves 20 are inclined bores 19 with a central bore 16 in connection dung, which ends as a blind hole above the bottom 15 Ai the central bore 16 closes at the top « Round chamber 18, which is used to hold the buffer piece! 9 is used, which also has a center hole. Over it there is a cavity, the side recess egg 24 and is intended to be the lower end 6 de; Shank 2 with the lugs 7 to receive. wear and tear Shoe 14 and shaft 2 are detachably connected to one another when the buffer piece 9 is inserted, indeir Bolts (not shown) in transverse bores 22 de: wear shoe 14 inserted and through (also! Longitudinal pins (not shown) are secured, which are inserted ir longitudinal holes 23. The bolts overlap the lugs 7 and thereby hold the shaft 2 ir Plant on the upper end face of the buffer piece 9 because: in the round chamber 18 of the wear shoe 14 untei Tension sits

The supply of flushing agent can be carried out on the assembled drill bit in the deep hole via the external longitudinal grooves 3, the inclined bores 5, the central bores 4, 12, 16 and the inclined bores 19 take place. The Abfuhi the flushing agent and the cuttings then go over the longitudinal grooves 20 of the wear shoe 14 in the open Space between shaft 2 or drill pipe and borehole in front of you. A recess 25 in the upper part of the Shank 2 (Figs. 8 and 9) is used to attach it.

For the sake of clarity, FIG. 6 the hard metal inserts, e.g. B. warts 21, omitted.

While in the drawn examples of the wear shoe 14 each has three longitudinal grooves 20 which are connected to the central bore 16 via three inclined bores 19, it is also possible To attach inclined bores 19 and longitudinal grooves 20 in greater numbers (see. Fig. 11). In general is an even circumferential distribution is preferable, but it can also be desirable and advantageous Similar to the inclined bores 5 on the shaft 2 (FIG. 7), the inclined bores 19 of the wear shoe 14 are also used focus on one side.

In contrast to the aforementioned embodiments, it is also possible according to the invention for the Components of the drill bit 1 to provide other connecting means, provided that these only - at least in Drive direction - non-rotatable and protected against impact deformation. A certain movement game can contribute to the fact that the connecting elements remain in their position during operation continuously change slightly so that a more even load is achieved and the wear and tear is reduced.

An example of this is shown in FIGS. 10 and 11 The drill bit 1 shown there is with its slightly enlarged guide head from above into a retaining cap 30 used, which forms the lower end of the housing of a deep hole hammer and has an annular shoulder on which the guide head of the drill bit shank 2 comes to rest in its end position Shank 2 has a cylindrical Q through hole 26 in this embodiment, while he is on his The outside has a polygonal profile of the type PC 4 {Fig. Ii). Corresponding form-fitting polygonal

«09353/329

# 646 *

ΠΙ has the lower inner part of the retaining cap 30.

The wear shoe 14 is releasably attached to the lower end of the shaft 2. For this purpose, the shaft 2 is provided with an annular groove 31 in which a preferably radially divided retaining ring 32 engages, which is held between a polygonal insert 33 and a threaded ring 36, which also has a polygonal profile and is expediently provided with recesses for inserting a tool. Below the shaft 2, the buffer piece 9 is seated under axial tension in the wear shoe 14. Radially there follows :; Buffer piece 9 has a flatter stop disk 35, which limits the pressure path of the shaft 2 within the guide or retaining ring 32. Such a stop disk can also be used with advantage in other drill bit embodiments.

Fi g. 11 also shows that the leadership resp. Retaining ring 32 is stepped or stepped on the outer circumference in the manner of a ratchet wheel and that on the form-fitting inner profile of the wear shoe 14 corresponding lugs 37 are formed. Between these Projections and the lugs 37 are supported in the circumferential direction from damping inserts 34, which in the drawn example are four parallel wedges, but also run obliquely and can be profiled differently. You can consist of the same elastic-yielding material as the buffer piece 9, for. B. off Polyurethane, special rubber or the like, and they are used to to dampen or intercept the rotary movements of the drill bit parts and to cause excessive wear to prevent the inner parts of the drill bit and to prevent the hard metal parts from breaking out.

Parts of a further embodiment of a drill bit 1 according to the invention are shown in FIGS. 12 and 13 This design is similar to the example of FIGS. 10 and 11, which is why similar elements with the same reference numbers are identified. The drilling

10

chisel shank 2, which in turn has a polygonal profile and has an annular groove 31 near its lower end is provided is axially held by a again divided Ting 32, which in this case by an upper

S ring part 40 is overlapped and secured axially. Of the upper ring part 40 and a lower sole part 42 together form the drill bit or the wear shoe 14, which is provided on its outer end face 15 with hard metal inserts or warts 21 and generally one

ίο has a structure similar to the example of FIGS. 10 and 11. Drill bit shank 2 and wear shoe 14 are penetrated by a through hole 26 in the lower Sole part 42 merges into a central bore 16 and inclined bores 19 into the lower sole part 42, the buffer piece 9 is partially countersunk, so that instead of a separate stop disk 35 (Fig. 10) the same function of limiting the travel of the drill bit shank 2 through the upper end face of the Sole part 42 is taken over. This has steps 43 on its circumference, which correspond to Steps 41 on the upper ring part 40 interact in a form-fitting manner by these alternating upwards and downstairs interlocking. The connection of the parts 40,42 can, for example, by means of Allen screws 44 take place, which are non-positively or positively secured and therefore not in use can loosen. The rotating entrainment of the wear shoe 14 is in turn by an am Outer circumference stepped insert 33 ensures the

3 "is padded in the circumferential direction by damping inserts 34

According to the invention, a combination of the designs of FIGS. 10 and 12 can also be considered, in that For example, the threaded ring 36 designed as an upper ring part 40 and by means of a screw connection, a Bayonet fastening or the like is attached to the lower sole part 42.

For this purpose 3 sheets of drawings

m 646 *

Claims (29)

Patent claims: 1. Drill bit for downhole hammers, with a drill bit widening towards the attack surface, which with flushing bores, recesses and hard metal inserts, in particular X-cutting edges, ribs, warts Od. The like., Is provided and with an outside having longitudinal grooves, opposite in cross section the drill bit reduced shaft with the drill bit designed as a wear shoe and with the shaft is interchangeably connected, characterized in that the wear shoe (14) is connected to the shaft (2) in an elastically buffered manner 2. Drill bit according to claim 1, characterized that between the shaft end (6) and an inner end face (17) of the wear shoe (14) a buffer piece (9) under tension sits in particular a cylindrical block, e.g. B. made of polyurethane, Special rubber or the like, with or without spring loading. 3. Drill bit according to claim 1 or 2, characterized in that the buffer piece (9) and wear shoe (14) are at least partially penetrated by a central bore (12; 16). 4. Drill bit according to claim 3, characterized in that the central bore (16) in the wear shoe (14) near the end face (17) of the latter ends as a blind hole and radially through z. B. three in regular central angles extending inclined bores (19) is continued. 5. Drill bit according to claim 4, characterized in that the inclined bores (19) on longitudinal external grooves (20) of the wear shoe (14) open. 6. Drill bit according to one of claims 3 to 5, characterized in that a central bore (4) is formed in the shaft (2) as a blind hole ending approximately in its longitudinal center, which is in oblique bores (5) passes, which open into the outer longitudinal grooves (3) of the shaft (2). 7. Drill bit according to claim 6, characterized in that the outer longitudinal grooves (3) to the center of the shaft taper towards the end. 8. Drill bit according to one of claims 1 to 7, characterized in that the shank (2) close its lower end (6) has at least two diametrically opposite lugs (7) behind which fastening bolts engage positively, which in transverse bores (22) of the wear shoe (14) sit and can be secured by longitudinal pins. 9. Drill bit according to one of claims 2 to 8, characterized in that the buffer piece (9) in a round chamber (18) of the wear shoe (14) is arranged, the side wall of which is undercut, is concave or provided with at least one annular groove. 10. Drill bit according to one of claims 2 to 9, characterized in that the buffer piece (9) has at least two materially connected parts of different density and / or elasticity, in particular a harder core (10) which is enclosed on all sides by a softer jacket (11) is. 11. Drill bit according to one of claims 2 to 10, characterized in that the buffer piece (9) has at least one closed-cell foam part owns 12. Drill bit according to one of claims 2 to 11, characterized in that the buffer piece (9) has at least one convex and / or at least one Has beveled end face (13) 13. Drill bit according to one of claims 2 to 12, characterized in that the buffer piece (9) is an essentially cylindrical flat ring 14. Drill bit according to one of claims 1 to 13, characterized in that the shaft (2) and the wear shoe (14) by a bayonet attachment are releasably connected. 15. Drill bit according to one of claims 1 to 14, characterized in that the shank (2) has a The annular groove (31) has a preferably split retaining ring arranged in the wear shoe (14) (32) intervenes 16. Drill bit according to one of claims 1 to 15, characterized in that the shaft (2) for mounting the drill bit (1) from above into a Retaining cap (30) can be inserted, which has an annular shoulder or similar stop parts at the bottom 17. Drill bit according to one of claims 1 to 16, characterized in that the shaft (2) and wear shoe (14) have a polygonal profile, in particular disharmonious PC4 profile. 18. Drill bit according to one of claims 1 to 17, characterized in that the wear shoe (14) contains at least one insert (33) whose Outer part set off on the circumference and padded in the circumferential direction with damping inserts (34) is. 19. Drill bit according to one of claims 2 to 18, characterized in that a flatter stop disk (35) adjoins the buffer piece (9) radially. 20. Drill bit according to claim 19, characterized in that the stop disc with the Wear shoe (14) formed in one piece and the buffer piece (9) is held sunk therein. 21. Drill bit according to one of claims 15 to 20, characterized in that for fastening the Wear shoe (14) on the drill bit shank (2) a threaded ring (36) axially securing the retaining ring (32) is available. 22. Drill bit according to claim 21, characterized in that the threaded ring (36) for Contact with a shoulder of the wear shoe (14) is one preferably provided with key surfaces (39) Has federal government (38). 23. Drill bit according to one of claims 1 to 22, characterized in that the wear shoe (14) is designed in two parts, an upper ring part (40) with a lower sole part (42) through secured fasteners is releasably connected, for. B. by Allen screws (44) with force or positive locking. 24. Drill bit according to claim 23, characterized in that the ring part (40) has the retaining ring (32) overlaps and has support parts resting on the sole part (42). 25. Drill bit according to claim 23 or 24, characterized in that the sole part (42) with the ring part (40) is toothed, preferably by means of alternating steps (41, 43) on the inner and / or outer circumference. 26. Drill bit according to claim 25, characterized in that the steps (41, 43) in the same Direction or in the same direction of rotation run flat or wedge-like as the noses or shoulders (37) on insert (33) and wear shoe (14). 27. Drill bit according to claim 25 or 26, characterized in that the steps (41, 43) are designed in the same way and have regular angular or circumferential distances. 28. Drill bit according to one of claims 1 to 27, characterized in that the shaft (2) and Wear shoe (14) consist of different materiai, for example from chisel steel high impact strength on the one hand and made of an abrasion-resistant alloy, such as X155CrVMol2 !, on the other hand. 29. Drill bit according to one of claims 1 to 28, characterized in that at least parts of the drill bit (1) are hard-borated, a surface layer of, for. B. 03 to 0.4 mm depth has a Vickers hardness in the area above about 1800 HV .