AU631054B2 - Rock drill - Google Patents

Abstract

The rock drill bit consisting of shank (1) and drill head (2) is provided with a cutting tip (4) as well as cutting pins (5) at the front end (3) of the drill head (2) pointing in the feed direction. The diameter on which the cutting tip (4) is arranged and the diameter on which the cutting pins (5) are arranged form an angle deviating from 90 DEG . An enlargement of the disposal flutes (6) is made possible by the deviation in the angle of both diameters. <IMAGE>

Description

COMMONWEALTH OF AUSTRALIA FORM PATENTS ACT 1952 COMPLETE S P E C I FICAT I ON FOR OFFICE USE. 0 Class Int.Class ApplicaLion 'umber: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: Name of Applicant: HILTI AKTIENGESELLSCHAFT Address of Applicant: Schaan, Liechtenstein Actual Inventor: Gerharc Rumpp, Josef Obermeier and Josef Fuenfer Address for Service: SHELSTON WATERS, 55 Clarence Street, Sydney 0 .0 S Complete Specification for the Invention entitled: "ROCK DRILL" The following statement is a full description of this invention, including the best method of performing it known to us:- 1 I I I -2 Rock Drill The invention relates to a rock drill, having a shaft and a drill head, that is equipped at its frontal face pointing in the direction of advance with at least one cutting tip extending over the full diameter and with at least two buttons.

Rock drills are utilised in the formation of boreholes in rock, in concrete, in masonry and the like, for the O: accomod.tion of fixing pieces, for the passage of pipes and of cables, as well as for blasting. Rock drills that employ 10 a combination of a cutting tip and buttons have the advantage that the cuttings removed from the cutting tip are further reduced in grain size. Such rock drills are known e.g. from DE-OS 35 44 433.

1 In a variety of operating conditions such familiar rock drills render satisfactory services. For the conditions prevailing in certain applications, however, the disposal of the fine-grain bore waste and the rate of advance of the drilling are not optimal.

The object of the invention is the creation of a rock drill, that will afford high drilling speeds together with an additional reduction in the grain size of the cuttings and with an accelerated removal of the fine-grain bore waste.

According to the invention this is attained by placing the buttons along a diameter that forms an angle differing from 90° with the diameter defined by the cutting tip.

By virtue of the arrangement of the buttons according to the invention an enlargement of the disposal grooves result.s.

It is of advantage to place the buttons along a diameter on both sides of the cutting tip. This opens up the possibility of a symmetrical arrangement.

10 This is valid in particular in the case when the number of buttons on both sides is the same. By making the number of buttons equal on both sides a more uniform crushing of the cuttings and a more quiet operation of the drill is achieved.

By employing two buttons, in particular in the zone of Sthe periphery of the boring head, the centring of the rock a drill during the drilling process is further enhanced.

S1 It is of advantage to position the buttons in a pattern of rotational symmetry with respect to the longitudinal axis of the shaft. This increases the quietness of operation of the rock drill and ensures greater accuracy in the geometry of the bore.

I- 7 I 4 The acute angle between the two diameters will with advantage have a value between 40 and 70°. Such an angle proved its worth in particular because in the domain of the complementary obtuse angles the arrangement of adequately large disposal grooves at the front face is especially facilitated.

In the regular manner, a helix is adjoined to the disposal grooves, determining the direction of rotation of .the rock drill. The acute angle formed by the diameters 10 defined by the cutting tip and by the buttons is preferably located at the side of the cutting tip opposite to the direction of rotation.

From the perspective of crushing the cuttings it has proved to be especially expedient to arrange the buttons ,with an inclination towards the longitudinal axis of the shaft. An arrangement of the buttons parallel to the longitudinal axis of the shaft is also thoroughly feasible.

The free-standing frontal ends of the buttons do not, preferably, fall into the rotational surface described by the cutting tip, but are slightly, e.g. by 0.3mm to offset against the direction of the bore. The rate of advance during the drilling process will thus be made more uniform, as the buttons make contact with the base material almost simultaneously with the cutting tip. This results in a more uniform reduction of the base material.

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In addition, the buttons assume the role of supporting the bore head in the direction of advance.

The invention is explained in greater detail below by way of an application example. Thus it is shown in: Fig.l a rock drill according to the invention in elevation view, Fig.2 a plan view of the front face of the rock drill illustrated in Fig.l, Fig.3 a section along the line III-III in Fig.2 of the rock drill according to Fig.1 and 2.

The rock drill as gathered from Fig.l to 3 consists essentially of a shaft 1 and of a bore head 2 joined thereto. The shaft 1 is provided with a transport helix 9, affording on the one hand a guide to the drill in the borehole and facilitating the disposal of fine-grain bore waste on the other hand.

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SaS The bore head 2 is provided with disposal grooves 6, running in the longitudinal direction and facilitating the passage of the fine-grain bore waste from the frontal face 3 of the bore head 2, pointing in the direction of advance, to the shaft 1. The bore head 2 is provided with a centrally located cutting tip 4. The cutting tip 4 extends 6 beyond the bore head 2 radially as well as in the direction of advance. At the remainder of the frontal end 3 of the bore head 2 buttons 5 are positioned along a diameter that Sforms an acute angle with the diameter defined by the cutting tip 4. This acute angle is situated as shown in Fig. 3 on the side opposite to the direction D of rotation of the cutting tip 4.

The section shown in Fig.3 indicates clearly the arrangement of the buttons 5 at a direction inclined with 10 respect to the longitudinal axis of the shaft. The buttons 5 are sunk into the bore head 2 so deeply that the S free-standing frontal ends of the buttons come to lie below j the rotational surface described by the cutting edges 7, 8 of the cutting tip 4.

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Claims (5)

1. 2. A rock drill according to Claim 1, wherein the drill buttons are arranged along the second diameter on both sides of the cutting tip.
2. 3. A rock drill according to any one of Claims 1 to 2, wherein the same number of drill buttons are situated on each side of the cutting tip.
3. 4. A rock drill according to any one of Claims 1 to 3, wherein the drill buttons are arranged in a formation having rotational symmetry with respect to the longitudinal axis of the shaft. A rock drill according to any one of Claims 1 to 4, wherein the acute angle is between 40 degrees and degrees.
4. 6. A rock drill according to any one of Claims 1 to wherein the drill buttons are inclined with respect to longitudinal axis of the shaft. A rock drill according to any one of Claims 1 to 6, wherein the free-standing frontal ends of the drill buttons are offset with respect to the rotational surface formed by the cutting edges of the cutting tip.
5. 8. A rock drill substantially as herein described with reference to the accompanying drawings. DATED this llth day of September, 1992 HILTI AKTIENGESELLSCHAFT Attorney: LEON K. ALLEN Fellow Institute of Patent Attorneys of Australia of SHELSTON WATERS I L