EP0322554B1 - Rock drill bit - Google Patents

Description

The invention relates to a rock drill according to the preamble of claim 1.

The spiral feed coils of rock drills are machined or machined to incorporate the flutes into the generally cylindrical starting material.

The main task of rock drill bits is the material loosened by the hard metal cutting edge, i.e. H. extract the drilling dust or cuttings from the borehole. The size of the drilling groove, i.e. H. The free cross-section of the conveyor plays a crucial role in the performance of the drill. H. good drilling dust transport ensures good feed and prevents chatter marks in the borehole and damage to the drill due to jamming, overheating or the like. If the drill jams, there is also a risk of accidents for the operator. A large drilling dust conveying groove with the appropriate shape therefore guarantees a sufficiently good drilling dust transport. This has a significant impact on the service life of the drilling tool.

In addition, to a certain extent the production helix still has to fulfill guiding properties in the borehole.

In order to do justice to the sufficient conveying of the drilling dust, the conveying groove cross section is chosen so large in known drills that there is a diameter ratio of the core diameter to the conveying helix diameter of approximately 0.5. Such a large conveying groove cross-section for transporting the drilling dust is necessary for high-performance tools. A large conveying groove cross section has the disadvantage that the core diameter of the conveying helix is greatly weakened. If the drill is blocked, breaks in the area of the core cross section weakened by the conveying groove can occur. At least very high-quality tool steel made of alloyed steels must be used to meet the requirements. The cross-section can also be weakened by core bores for the cooling medium.

From German utility model no. 6 933 778, a drilling tool for use as a rock drill with a hard metal cutting tip has become known, which consists of a rolled basic profile with two longitudinal ribs and whose feed spiral is produced by twisting or twisting the basic profile. With a drilling tool of this type, the ratio of the helix diameter to the core diameter is> 0.5, as is customary with rock drills. However, the helix formed by the twisted longitudinal ribs has only unsatisfactory transport properties for the drilling dust due to its shape. In particular, there are congestion and jamming due to the small conveying groove cross section. The drilling properties of such a tool are far inferior to normal drilling tools in terms of drilling dust transport. This also applies to the tools according to DIN 20 377, July 1979.

In order to obtain a satisfactory conveying performance of the drilling dust in the helix, a certain minimum amount of free cross-section is therefore necessary, which generally leads to a weakening of the core diameter of the helix and accordingly requires expensive starting materials to reduce the risk of breakage.

The invention has for its object to provide a drilling tool, in particular en rock drill for impact stress, which avoids the disadvantages mentioned above, in particular equally good or improved conveying properties with a smaller conveying groove cross-section, i. H. has a larger core diameter or core cross section.

This object is achieved on the basis of a rock drill of the initially characterizing type according to the invention by the characterizing features of claim 1.

Advantageous further developments and improvements of the rock drill specified in the main claim are possible due to the features listed in the subclaims.

The invention is based on the knowledge that an improvement in the conveying properties of conveying helixes is only possible through constructive measures within the conveying groove. However, if the conveying properties of a conveying groove are improved in such a way that a smaller conveying cross section for drilling dust is sufficient for the same conveying quantity, the core diameter or the core cross section of the conveying helix can be made larger. This improves the strength of the drill core in the area of the feed helix, ie the risk of breakage is reduced. An improvement or maintenance of the good conveying properties despite the reduced size Conveying groove cross section also has the advantage that a material with lower strength properties can be used due to the larger core diameter. As a result, a cheaper starting material can be used for the production of the conveyor helix.

The improvement or maintenance of the good conveying properties despite the reduction in the conveying groove cross section and thus the enlargement of the core cross section is achieved according to the invention in that several conveying grooves interact. According to the invention, therefore, in particular a continuous and uninterrupted main conveying groove is formed which interacts with a secondary conveying groove with a smaller pitch. The secondary conveyor groove is formed by conveyor ribs which are located in the main conveyor groove. Due to the flatter slope, ie a larger swirl angle, the secondary conveyor groove runs with a smaller pitch than the main conveyor groove. This results in a constant additional relative movement of the drilling dust transported in the main production groove, which leads to a loosening and thus to a better transport of the drilling dust in the main production groove. The conveying ribs of the secondary conveying groove accordingly significantly improve the conveying capacity of the drilling dust by shifting and loosening, which has the consequence that an otherwise inadequate conveying groove cross section, which tends to become blocked, is nevertheless sufficient for optimal drilling dust transport. That is, the improved conveying properties as a result of the interaction of the main conveying groove and the secondary conveying groove mean that optimal conveying properties can also be achieved with a smaller conveying groove cross section. The smaller conveying groove cross section, however, enables a larger core cross section of the conveying helix, which contributes to increasing its strength against the risk of breakage or permits the use of material of lower strength.

Overall, the conveying properties are decisively improved by an interaction of the main conveying groove with intermediate conveying ribs of the secondary conveying groove with a smaller pitch, which leads to a reduction in the conveying groove cross section and thus to a more favorable ratio of core diameter to conveying screw diameter.

In a further development of the invention according to subclaim 2, the limiting profiles or longitudinal profiles of the main conveying groove and / or the interrupted conveying ribs of the secondary conveying groove have suitable cross-sectional profiles, in particular a square, trapezoidal or circular cross-section. Any known profile can be used for the main conveyor groove. The essence of the invention therefore lies in the additional equipment of a suitable continuous main conveyor groove with individual conveyor ribs to form a secondary conveyor groove.

According to subclaim 3, the diameter of the secondary conveying groove formed by the conveying ribs is the same size or smaller than the diameter of the main conveying groove formed by the longitudinal profiles. The correct ratio of the height of the secondary conveyor groove can be determined empirically in order to achieve the optimal effect of the conveyor with a small conveyor groove cross section.

In a further development of the invention according to subclaim 4, the ratio of the core diameter to the diameter of the main conveying groove is approximately 0.8. Compared to the value of approx. 0.5 for conventional drills, this means a substantial reinforcement of the core cross-section with equally good conveying properties, since the diameter with exponent 2 (square) increases the cross-sectional area (F = π d² / 4).

According to subclaim 5, the main conveying groove and / or the secondary conveying groove can be formed either by machining, non-cutting machining or by turning a wing profile steel, as described in the introduction to the description.

According to the development of the invention according to subclaim 6, the main conveying groove is created in that a separate longitudinal profile is applied and fastened in a correspondingly introduced helical recess. With this structure, the manufacturing process can be simplified.

According to subclaim 7, the secondary conveyor groove is formed in that pocket-shaped recesses or cutouts are produced with the conveyor ribs formed in between.

This cutting shape enables a wide variety of rib shapes to be formed for the secondary conveyor groove.

According to subclaim 8, the conveying ribs of the secondary conveying groove can have different swirl angles, ie. H. have different heights. The material loosening is caused by the ratio of the different slopes of the main and secondary conveyor groove and by different slopes of the secondary conveyor groove itself. For this, preferred values are given in sub-claim 9.

According to the further subclaims 10 and 11, a twisted wing profile with longitudinal ribs is used as the starting material for the conveying helix to form a main conveying groove, the conveying ribs for the secondary conveying groove also being used as webs in the initial profile are rolled on. However, only a twisted wing profile can be used, the wings of which form the main conveying groove and into which the conveying ribs for the secondary conveying groove are introduced by machining. A well-known profile rolled steel according to DIN 488 parts 2 and 3 is a suitable starting material for a drilling tool with main conveyor groove and secondary conveyor groove; 6/86.

If a material with lower strength values is used as the conveyor helix, regardless of whether this consists of a twisted wing profile or a milled solid material, the clamping shank for the hammer drill should be made of a higher quality material, the connection between the different materials being made, for example, by means of a friction weld connection or soldering or the like.

The development of the invention according to subclaim 14 with a central through hole is made possible by the larger core cross section. The material transport can be further improved by a suction hole. The weight of the drill is also reduced. Here, in particular a thick-walled tube can be used as the starting material.

According to the advantageous features of subclaims 15 to 17, a specially matched drill head enables optimum assignment of the drilling dust from the drill head to the drilling dust grooves by assigning the cutting plate to the longitudinal profiles or longitudinal ribs. The additional cutting pins in the calculation of the end face of the drill head ensure that the drilling dust is present as a sufficiently fine substrate so that it can be transported unhindered in the flat drilling dust grooves.

Fig. 1

eine Seitenansicht eines erfindungsgemäßen Bohrers,

Fig. 2

eine Draufsicht entlang der Schnittlinie I-I in Fig. 1 mit Varianten der Hauptförderwendel,

Fig. 3

eine alternative Ausführungsform eines Bohrers in Seitenansicht mit eingefrästen Taschen,

Fig. 4

eine Draufsicht entlang der Schnittlinie II-II,

Fig. 5

eine Seitenansicht eines Bohrwerkzeugs aus einem verdrillten Ausgangsmaterial,

Fig. 6

eine Variante von Fig. 5 mit unterschiedlichen Förderrippen,

Fig. 7

einen Schnitt entlang der Schnittlinie III-III in Fig. 6,

Fig. 8

eine Seitenansicht und

Fig. 9

eine Draufsicht eines bevorzugten Bohrerkopfes.

Advantageous and expedient embodiments of the invention are shown in the drawing and explained in more detail in the following description. Show it

Fig. 1

a side view of a drill according to the invention,

Fig. 2

2 shows a plan view along section line II in FIG. 1 with variants of the main conveyor spiral,

Fig. 3

an alternative embodiment of a drill in side view with milled pockets,

Fig. 4

a plan view along the section line II-II,

Fig. 5

2 shows a side view of a drilling tool made of a twisted starting material,

Fig. 6

5 with different conveyor ribs,

Fig. 7

6 shows a section along the section line III-III in FIG. 6,

Fig. 8

a side view and

Fig. 9

a plan view of a preferred drill head.

The rock drill shown in side view in FIG. 1 and in cross section in FIG. 2 has a feed helix (1), a drill head (2) with a hard metal cutting element (3) and a clamping shaft (4). The arranged between the clamping shaft (4) and drill head (2) two-start feed helix (1) with a cylindrical core cross-section (13) consists of the two main feed grooves (5, 5 '), formed by the two helical longitudinal profiles (6, 7). The main conveyor groove (5, 5 ') formed by the longitudinal profiles (6, 7) has a small swirl angle γ ₁ ≈ 15 to 25 °, ie a relatively steep slope. In the main conveyor groove (5, 5 ') is a secondary conveyor groove (8) embedded, embedded or integrated, formed or limited by the conveyor ribs (9), with a larger swirl angle γ₂ between 30 to 80 °, preferably 35 °. The slope of the secondary conveyor groove (8) is therefore much flatter than that of the main conveyor groove (5). This results in a large number of conveying ribs (9) which limit the secondary conveying groove (8). The secondary conveyor groove (8) is limited by the longitudinal ribs (6, 7) of the main conveyor groove (5), but it continues in the second main conveyor groove (5 '). Accordingly, individual conveyor rib sections (9) are formed. The secondary conveyor groove (8) can therefore be regarded as a helical groove interrupted by the longitudinal profiles (6, 7).

In Fig. 1, the main conveyor groove (5) shown in the front view executes just half a pitch H / 2. About six conveyor rib sections (9) come to rest in this area. The pitch H of the main conveyor groove (5) therefore corresponds to the pitch h of the secondary conveyor groove (8) as 1:12. However, these values can vary.

The drill diameter D is determined by the carbide cutting element (3). The diameter d 1 of the main conveyor groove (5) formed by the longitudinal profiles (6, 7) is slightly smaller than the diameter D of the hard metal cutting edge (3). Here the carbide cutting edge protrudes approx. S ≈ 0.3 to 2 mm per side. The core diameter d₂ of the cylindrical core of the conveyor helix (1) relates to the diameter d₁ of the main conveyor groove (5) formed by the longitudinal profiles (6, 7) as follows: d₂: d₁ ≈ 0.8. It follows from this that the free conveying cross section of the main conveying groove is considerably smaller than in conventional drilling tools, where the ratio is approximately 0.5.

The diameter d₃ of the secondary conveyor groove (8) formed by the conveyor ribs (9) is slightly smaller than the diameter d₁ of the longitudinal profiles (6, 7) and lies between the values of d₁ and d₂.

In the exemplary embodiment according to FIG. 1, the drilling tool consists of a cylindrical core area (13) with incorporated or applied longitudinal profiles (6, 7) to form the main conveying groove (5, 5 ') and likewise incorporated or applied conveying ribs (9) to form the secondary conveying groove ( 8th). For example, the secondary conveyor groove (8) with conveyor ribs (9), with a flat slope, can first be produced as a continuous, initially uninterrupted conveyor spiral (8). Then two helical recesses or cutouts are made in the form of the longitudinal profiles (6, 7) to be used, which separate the initially continuous helical secondary conveyor groove (8) with conveyor ribs (9) into individual conveyor rib sections (9). As can be seen from FIG. 2 in an alternative embodiment, the longitudinal profiles (6, 7) with a circular cross section (10) or square cross section (11) or the like are then inserted into the recess produced in this way and fastened, for example, by means of a soldered connection (12) . The recess can extend into the core area (13) of the conveyor helix (1).

In Fig. 1, the two-course main conveyor groove (5, 5 ') for the drilling dust is formed by the longitudinal profiles (6, 7), which are designed as recessed profiles (10, 11). This main conveyor groove (5, 5 ') is then divided by the conveyor ribs (9) into a plurality of secondary conveyor grooves (8). This results in the relative movement of the drilling dust during transport in the helix (1).

In Fig. 1 and in plan view in Fig. 2, the core region (13) is cylindrical.

As shown in FIG. 3 and in plan view in FIG. 4, the core area of the main conveying groove (5) can also have other geometrical shapes. So the drilling tool in Fig. 3 in cross section consists of an initially circular cylindrical wing profile (13) with the longitudinal profiles (6, 7) to form a double-start conveyor helix (1) with main conveyor grooves (5, 5 '). The diameter formed by the longitudinal ribs (6, 7) is again indicated with d₁. The secondary conveying grooves (8) with the conveying ribs (9) are produced in the exemplary embodiment according to FIGS. 3 and 4 in that a part (14) of the initially circular core region (13) tangentially z. B. is milled, so that recesses or pockets (14) form. The conveyor ribs (9) and thus the secondary conveyor grooves (8) are formed here. The core diameter decreases in this area to d₂ '. The depth of the recess (14) depends on the desired geometric shape. Normally, it is a flat recess (14), which in special cases can, however, also have a curved, convex or concave configuration.

The drilling tools shown in FIGS. 5 to 7 are a rolled and then twisted or twisted circular cylindrical wing profile (15) as the starting material with rolled longitudinal ribs (16, 17) to form a main conveying groove (18). Before the twisted state, the longitudinal ribs (16, 17) run parallel to the drill center axis (19). After twisting or twisting, the longitudinal ribs (16, 17) shown in FIG. 5 result to form the main conveying groove (18).

5, the secondary conveyor groove (20) is formed by the conveyor ribs (21), with the swirl angle γ₂ as previously described. The helix angle of the main conveyor groove (18), formed by the Longitudinal webs (16, 17) is designated with γ₁. The conveying ribs (21) for forming the secondary conveying groove (20) are already present in the initial profile as transverse webs between the longitudinal ribs (16, 17).

5 also shows half the pitch H / 2 of the main conveying groove (18) and the distance h between the conveying ribs (21). The ratio H: h ≈ 1:12.

The cross section of the conveying ribs (21) is similar to that of the longitudinal ribs (16, 17), these cross sections in particular being trapezoidal. Each conveyor rib (21) extends between the two longitudinal ribs (16, 17), the trapezoidal height of the cross section of the conveyor ribs (21) towards the end regions continuously decreasing towards zero. The conveyor ribs (21) therefore merge into the core surface of the groove at its outlet.

In the embodiment of FIG. 6, a further variation of the swirl angle γ₂ is provided. For example, the twist angle γ₂, γ₂ ′, γ₂˝ can have different values between 30 and 80 °, the respective twist angle γ₁ of the main conveyor groove (18) always being smaller than the twist angle γ₂ of the secondary conveyor groove. As a rule of thumb can be viewed: γ₂ ≈ 2 x γ₁. 6 is γ₂ ≈ 35 °, γ₂ '≈ 40 to 45 °. If a third type of conveyor ribs (21) is also provided, the angle γ₂˝ ≈ 60 to 65 °. Here, the conveyor rib with the largest swirl angle γ₂˝ is arranged between the two conveyor ribs with the smaller swirl angles γ₂, γ₂˝. The shape of the exemplary embodiments according to FIGS. 5 to 7 can be found, for example, in DIN 488, Part 2, 6/86.

The clamping shaft (4) shown in Figures 1 and 5 is with the respective conveyor helix (1) z. B. attached via a friction weld (22). High-quality tool steel is used as the material for the clamping shank (4) in order to withstand the load in the rotary hammer. In the meantime, a material with lower strength properties, for example normal structural steel, is sufficient as the material for the conveyor helix (1), since the increase in cross-section of the core increases the strength with the same conveying capacity.

The basic idea according to the invention can therefore possibly be implemented with a conveyor spiral made of conventional cold-wound profile rolled steel with longitudinal ribs and oblique ribs, as is known according to DIN 488, parts 2 and 3, June 86 edition. This is all the more astonishing, since such inferior materials have basically been denied suitability for use for such tools. It is therefore surprising that the low strength values of such a profile rolled steel can be sufficient for use as a conveyor spiral. Of course, in special cases, further measures corresponding to the embodiment of the invention according to Figures 1 to 4 may be appropriate.

In Figures 2, 4 and 7, a central bore or through bore (23) is shown in dashed lines as an alternative solution. This hole can be used as a suction hole or coolant hole. In addition, the use of a thick-walled tube as a starting material for the conveyor spiral is then appropriate.

As can be seen from FIGS. 1, 3, 5, 6 and from FIG. 8, the drill has a drill head (2) with a diameter of over the entire diameter Cutting head (2) extending cutting plate (3) made of hard metal. The cutting plate (3) is arranged such that it is aligned with its outer, lower end (25) with the longitudinal profiles (6, 7) or the longitudinal ribs (16, 17), ie the longitudinal profiles (6, 7) or Longitudinal ribs (16, 17) pass almost continuously in the area of the drill head into the laterally protruding ends of the cutting element (3). This can be seen, for example, from FIG. 6.

According to FIGS. 8 and 9, the preferred embodiment of the drill head further provides that cutting pins (26, 27) are arranged on the end face (24) of the drill head (2). These cutting pins (26, 27) can be arranged in their longitudinal axis (28) parallel or at an angle δ to the central axis (19) of the drill.

The cutting pins (26, 27) can be distributed symmetrically (27) or asymmetrically (26) on the end face (24) of the drill head. The radial arrangement of the pins (26, 27) can also vary, i. H. the pin (26) lies on an inner radius r₁, the pin (27) on a larger radius r₂. In special cases, a further cutting pin (29) can be arranged on an outermost radius r₃ (see FIG. 9), this outermost cutting pin (29) coming to rest almost or on the diameter D formed by the cutting plate (3). (The cutting pin (29) is not shown in FIG. 8.)

The cutting pins (26, 27, 29) made of hard metal support the drilling result considerably, in particular with regard to the fine grain of the drilling dust. A finer drilling dust can, however, be better transported in the grooves with a small groove cross-section without the tendency to clog. In this respect, the drill head is an optimal addition to the helix design according to the invention.

Claims (17)

1. Rock drill for rotary and percussive duty, with a drill head equipped with a carbide tip, a chucking shank and at least one spiral conveying helix, characterised in that the conveying helix (1) consists of a single-thread or multi-thread, continuous, non-interrupted helical main conveying groove (5, 18), with helical secondary conveying grooves (8, 20) mounted in the latter and formed from conveying ribs (9, 21), the main conveying groove (5, 18) having a steep pitch or a small angle of twist γ₁ and the secondary conveying groove (8, 20) having a small pitch or a large angle of twist γ₂.
2. Drill according to Claim 1, characterised in that the continuous main conveying groove (5, 18) and/or the secondary conveying groove (8, 20) are formed by helical longitudinal profiles (6, 7; 16, 17) and/or conveying ribs (9, 21), with for example a square cross-section (11), trapezoidal cross-sections (16, 17), circular cross-section (10) or the like.
3. Drill according to Claim 1 or 2, characterised in that the diameter d₃ of the secondary conveying groove (8, 20) formed by the conveying ribs (9, 21) is of the same size or is smaller than the diameter d₁ of the main conveying groove (5, 18) formed by the longitudinal profiles (6, 7; 16, 17).
4. Drill according to Claim 1 or 2, characterised in that the ratio of the core diameter d₂ of the conveying helix (1) to the diameter d₁ of the main conveying groove amounts to approximately 0.8.
5. Drill according to Claim 1, characterised in that the main conveying groove (5, 18) and/or the secondary conveying groove (8, 20) are formed by cutting or non-cutting machining and/or by rotating a former.
6. Drill according to Claim 1, characterised in that the main conveying groove (5) is formed by at least one helical recess intersecting the continuous, helical secondary conveying groove (8), with a helical longitudinal profile (6, 7) inserted therein and attached, for example with a square cross-section (11), a circular cross-section (10) or trapezoidal cross-section or the like.
7. Drill according to Claim 1 or 5, characterised in that the secondary conveying groove (8) is formed by pocket-like recesses (11) in the main conveying groove (5).
8. Drill according to Claim 1 or 5 or 7, characterised in that the adjacent conveying ribs (9, 21) of the secondary conveying groove (8, 20) have a different angle of twist γ₂, γ₂', γ₂''.
9. Drill according to one or more of the preceding Claims, characterised in that the ratio of the angle of twist γ₁ of the main conveying groove (5, 18) or of the longitudinal profiles (6, 7; 16, 17) with respect to the angle of twist γ₂ of the secondary conveying groove (8, 20) or of the conveying ribs (9, 21) amounts to approximately 1 : 2 to 1 : 3.
10. Drill according to one or more of the preceding Claims, characterised in that the angle of twist γ₁ of the main conveying groove (5, 18) amounts to approximately γ₁ ≈ 15 to 60°, preferably 15 to 25° and the angle of twist γ₂, γ₂', γ₂'' of the secondary conveying groove (8, 20) amounts to approximately γ₂ ≈ 30 to 80°, preferably γ₂ ≈ 35°.
11. Drill according to one or more of the preceding Claims, characterised in that as the starting material for the conveying helix (1) it is possible to use a rolled and then turned or twisted wing profile (15) with at least one longitudinal rib (16, 17) for forming a helical main conveying groove (18), the initial profile (15) comprising webs for forming the conveying ribs (21) of the helical secondary conveying groove (20).
12. Drill according to one or more of the preceding Claims, characterised in that as the conveying helix (1), for example a profile can be used which is constructed as a rolled steel profile according to DIN 488, parts 2 and 3, June 1986.
13. Drill according to one or more of the preceding Claims, characterised in that the conveying helix (1) consists of structural steel or profiled rolled steel and is connected to a chucking shank (4) for drill hammers consisting of an alloyed tool steel by means for example of a friction welded connection (22).
14. Drill according to one or more of the preceding Claims, characterised in that the conveying helix (1) has a central through hole (23) as a suction bore or coolant bore or the like, a tube preferably being able to be used as the starting material.
15. Drill according to one or more of the preceding Claims 1 to 14, characterised in that on its end face (24), the drill head (2) has a carbide cutting tip (3) extending over the entire diameter D of the drill head, the longitudinal profiles (6, 7) or the longitudinal ribs (16, 17) ending directly in the outer, lower region (25) of the cutting tip (3) and aligning with the projecting part(s) of the cutting tip.
16. Drill according to one or more of the preceding Claims 1 to 15, characterised in that in addition to the cutting tip (3), the drill head (2) comprises carbide cutting pins (26, 27, 29) on its end face (24), the cutting pins being arranged symmetrically or asymmetrically with respect to the planes of symmetry of the drill and being arranged radially at the same or different positions.
17. Drill according to Claim 16, characterised in that the cutting pins (26, 27, 29) are aligned with their longitudinal axis (28) axis parallel to or inclined with respect to the longitudinal axis (19) of the drill.

Images