WO2002066793A1

WO2002066793A1 - Tool head and tool for undercutting

Info

Publication number: WO2002066793A1
Application number: PCT/SE2002/000261
Authority: WO
Inventors: Peter Nava
Original assignee: Sandvik Ab
Priority date: 2001-02-23
Filing date: 2002-02-15
Publication date: 2002-08-29
Also published as: SE522997C2; SE0100622L; ZA200306736B; SE0100622D0

Abstract

The present invention relates to a tool head (46) and a tool (10) for mining of rock material by means of undercutting. The tool head (46) comprises an holder and a number of tools (10) provided at the periphery of the holder. Each tool (10) comprises a roller cutter rotatably journalled via bearing means to an attachment. The roller cutter has a number of cemented carbide buttons provided in a row along the periphery of the roller cutter. The tool head and the tools have opposite directions of rotation during machining.

Description

Tool head and tool for undercutting

Area of the invention

The present invention relates to a tool head and a tool for mining of rock material according to the preambles of each of the appended independent claims.

Technical background

Through DE-A1-39 05 737, DE-A1-41 42 800 and US-A-2,619,338 tool heads are known that break rock material with the assistance of tools which during drilling follows a curved path. The known tool heads work by undercutting to mine large amounts of rock material rationally without creating much dust. However, the known tools have poor life spans.

Objects of the invention

One object of the present invention is to provide a tool head and a tool having the same advantages as known technique. Another object of the present invention is to provide a tool head and a tool with a good life span.

Still another object of the present invention is to provide a tool head and a tool, which require relatively little energy during operation.

Still another object of the present invention is to provide a tool head and a tool with good mining capacity.

These and other objects have been achieved by a tool head and a tool such as they are defined in the appended claims with reference to the drawings.

Brief description of the drawings Fig. 1A shows a tool according to the present invention in a side view partly in a section. Fig. 1 B shows the tool in an additional side view. Fig. 1C shows the tool in an end view. Fig. 2A shows a tool head according to the present invention 11648DE 2002/02/13 2

in a side view. Fig. 2B shows the tool head in an end view. Fig. 3A shows a plan view of a machine for mining of rock material. Fig. 3B shows the machine in a perspective view.

Detailed description of a preferred embodiment of the invention

Figs. 1A-1C show a tool 10 for mining of rock material by undercutting. The tool comprises a rectangular, elongated attachment 11 and a roller cutter 12. A bearing journal 13 is integrally formed with the attachment 11 and the roller cutter 12 is mounted on the journal 13. The roller cutter 12 has a number of rock cutting means, preferably in the shape of cemented carbide buttons 14 arranged in a row at a distance from each other in the circumferential direction. Said distance is at least twice the size of the button 14 diameter. With the expression " cemented carbide" is meant a metal carbide, such as tungsten or similar, sintered together with a binder, such as cobalt or nickel. A number of bearing arrangements are formed between the roller cutter 12 and the journal 13, whereby the roller cutter 12 is symmetrical and rotatable relative to the journal 13 around an axis of rotation CL.

Thus a radial base bearing is provided in connection with the open end of the roller cutter 12, and said radial base bearing comprises a number of cylindrical first rolling elements 15, which cooperate partly with a first bearing race 16 on the journal and partly with a second bearing race 17 at the inside of the roller cutter 12 in connection with the open end.

A radial top bearing is provided closer to a free end of the journal 13 than the base bearing, and said top bearing likewise comprises a number of cylindrical second rolling elements 18, which normally have a smaller diameter than the first rolling elements 15 of the base bearing and partly cooperates with a third bearing race 19 on the journal 13; partly with a fourth bearing race 20 at the inside of the roller cutter 12.

A first and a second support disc 21 and 22, respectively, are formed as a first axial bearing provided at the area of the forward free end of the journal 13 (Fig. 1 B). The first support disc 21 is received by a first recess in the roller cutter 12, and said first support disc 21 is striated along its circumference for a 11648DE 2002/02/13 3

safer attachment to said first recess. The material in the first support disc 21 is preferably high-speed steel. The second support disc 22 is received by a second recess at the free end of the journal 13, and the second recess is usually circular while the second support disc 22 is hexagonal or octagonal, whereby the second support disc 22 is prevented from rotating relative to the journal 13. The material in the second support disc 22 is preferably cemented carbide.

A system of roller bearings is provided between the base bearing and the top bearing. A channel 25 for the insertion of roller bearing balls 23 is provided in the bearing journal 13, in which a plug 24 is received such to retain the separate balls 23. A weld seals the channel 25. The first rolling elements 15 receive a major part of the force of reaction from the rock while the principal task of the balls 23 is to retain the roller cutter 12 on the journal 13. The roller cutter has shoulders 26 and 28 to be brought against collars 27 and 29, respectively, on the journal for receiving axial forces, which are not received by the cooperation of the support disc 21 with the support disc 22 of the journal. The shoulders and collars 26-29 form right angles with the rotational axis CL. The collar 29 is provided on a cylindrical base portion 36 connected to the attachment 11. The shoulder 28 forms together with the collar 29 a first protection against entrance of rock dust. An O-ring 34 is inserted in a cavity between said first protection and said first rolling elements 15 as a second protection against entrance of rock dust. The above-captioned bearings may be lubricated by means of a lubricating system integrated with the tool 10. A slide bearing can be provided at the substantially corresponding position according to Fig. 1 A instead of the second rolling elements 18. The buttons 14 of cemented carbide are secured along a circumferential protrusion 30 on the roller cutter 12. The centerline CL2 of each of button forms an angle α with the axis of rotation CL of the roller cutter. The angle α is 60 to 80°, preferably about 75°. All buttons 14 intersect a plane P. The plane P is provided axially beyond the closest bearing 21 , 22. All buttons 14 in one tool are generally facing away from the attachment 11. The roller cutter 12 comprises a substantially planar end surface 31 , which is parallel with the plane P and which connects to a substantially conical peripheral surface 32. The planar end surface 11648DE 2002/02/13

is massive, which means that dust cannot enter into the bearings that way. The peripheral surface 32 comprises holes which hold the buttons 14. The peripheral surface further connects to an axially rearwardly tapering surface 33, which has a breaking function in tough minerals. The surface 33 may include wear protection in the shape of a hard-facing deposit or a number of cemented carbide buttons 35. The surface 33 further connects to a cylindrical envelope surface of the roller cutter 12. The envelope surface is aligned with the envelope surface of the cylindrical base portion 36.

The attachment 11 has four through-going, un-threaded, holes 37 that extend perpendicularly to the rotational axis CL. The holes are intended to receive threaded screws for clamping the attachment to a holder 38. The holder

38 has a polygonal, preferably hexagonal, basic shape. The holder 38 has an axis of rotation CL3 as well as a number, preferably six, of recesses 39 adapted to receive the attachments 11. The recesses are consequently rectangular and open outwards in the radial direction of the attachment and are spaced with a 60° partition. The bottom 40 of each recess 39 is essentially planar and parallel with the rotational axis CL3 and comprises four threaded blind holes 41. The holder 38 has a center hole 42 intended to be positively clamped to a machine driven shaft via for example a splines joint such to be rotated during operation. Alternatively the axis of rotation of the roller cutter form an acute angle with the rotational axis CL3, which angle is chosen in the range of 1 to 30°, preferably 5 to 15°. Said angle is obtained most simply by inclining the bottom of the recess

39 downwardly such that its imaginary extension line intersects the axis CL3 at the side of the head where the roller cutters are. By inclining the tool in that manner a bigger clearance is obtained for not active parts of the tool and a more favorable angle of attack for the buttons in action.

The tool 10 is mounted to the holder 38 by positioning the attachment 11 in the recess 39 such that the four holes 37 of the attachment align with the four threaded holes 41 in of the recess bottom 40. The screws are inserted through the holes 37 and are screwn into the holes 41. Thereby the lower side 11 A of the attachment is fixed against the bottom 40. The procedure is repeated until all recesses comprise a tool. The upper side 11 B of the attachment will then be in 11648DE 2002/02/13 5

position substantially in line with the envelope surface of the holder such to minimize possible impacts against the holder. The tool head that is formed by the holder 38 and the tools 10 is depicted 46.

The holder in turn is intended to be mounted to a machine 43, see Figs. 3A and 3B. The machine 43 has an arm 44 pivotable to-and-fro, which is driven via hydraulic means 45. The arm 44 comprises a driven axis, not shown, which is mounted to the hole 42 in the holder. The arm pivots about an axis A such that the tool head 46, the center line of which is provided somewhat in front of the axis in the initial position, follows an essentially arcuate path with a radius R during continuous rotation in the direction R1 of the tool head 46. The rotation R2 of the tools 10 becomes reversed to the rotation R1 of the tool head since the part of each tool periphery which is foremost in the direction of the path machines rock. The machine is foremost intended to machine ore such as platinum ore, where the ore lies in narrow layers in the rock. The height of the machine is therefore adapted not to outreach the biggest diameter of the tool head.

Such as is evident from Figs. 3A and 3B the initial position of the machine 43 that the arm 44 is perpendicular to the direction F of motion of the machine. When the machine has been fixed via not shown means in that position rotation of the driven axis, not shown, is started such that the tool head 46 is brought to rotate in the direction R1. Subsequently the arm 44 starts to pivot about the axis A and a part of at least one tool 10 periphery, i.e. some buttons 14, engage with the rock. Thereby a rotation of the tool in direction R2 arises due to reactional forces and the buttons pulverizes rock with continuously increasing cutting depth. After pivoting the arm 44 a certain number of degrees the cutting depth will outreach the diameter of respective button. Thereby arises undercutting of the rock, i.e. a tongue of not machined material comes to abutment against the conical tapering surface 33 of the tool 10 or against a side of the button top whereafter the tongue simply is broken loose such as is shown with dashed lines in Fig. 3A. Frequently three buttons are in action simultaneously which gives a high surface pressure on each cemented carbide button in relation to surface pressure on steel discs according to prior art. This gives good penetration for 11648DE 2002/02/13 g

each button and requires less energy simultaneously as the generated dust is not compressed in the formed trail but finds accommodation between the buttons, which entails a good life span for the tool. The momentarily passive tools obtain a clearance relative to the machined surface. When the arm has swung about 120° in relation to the initial position the pivoting is stopped and the arm returns to said position. Thereby the tool head has cut away material enough such that the machine will be able to advance a further distance in the direction F, for example 6 cm. The machine can be provided with a device so as to shove the loose ore. The disclosures in Swedish patent application No. 0100622-0, from which this application claims priority are incorporated herein by reference.

Claims

11648DE 2002/02/13 7Claims

1. Tool for mining of rock material by means of undercutting, said tool comprising a roller cutter (12) rotatably journalled via bearing means (15,18,23) to an attachment (11 ), characterized in that the roller cutter (12) has a number of cemented carbide buttons (14) provided in a row along the periphery of the roller cutter and in that said buttons (14) are generally facing away from the attachment (11).

2. The tool according to claim 1 , characterized in that the buttons (14) form an angle (α) with an axis of rotation (CL) of the roller cutter, said angle (α) being preferably 60 to 80°, most preferably about 75°.

3. The tool according to claim 1 or 2, characterized in that all buttons (14) intersects a plane (P) that is provided axially beyond the closest bearing (21 , 22).

4. The tool according to claim 3, characterized in that the roller cutter (12) comprises a substantially planar end surface (31), which is parallel with the plane (P).

5. The tool according to anyone of the preceding claims, characterized in that the roller cutter (12) is provided on a bearing journal (13), which is formed integrally with the attachment (11), said roller cutter and said bearing journal comprising a first protection (28,29) against entering rock dust.

6. The tool according to claim 5, characterized in that the roller cutter (12) and the bearing journal (13) comprise a second protection (34) against entering rock dust.