EP3237139A1

EP3237139A1 - Method for manufacturing a continuous drill ring for a core drill bit

Info

Publication number: EP3237139A1
Application number: EP15820141.8A
Authority: EP
Inventors: Matthias Mueller; Marcel Sonderegger
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2014-12-22
Filing date: 2015-12-22
Publication date: 2017-11-01
Also published as: RU2667114C1; CN107107223A; AU2015371098B2; US20170361388A1; EP3037201A1; KR20170093981A; WO2016102523A1; BR112017012774A2; AU2015371098A1

Abstract

Method for manufacturing a continuous drill ring (51) for a core drill bit, involving the steps of: forming at least two green compacts in layers in a direction of formation between a bottom side and a top side by successively applying powder layers containing a powder mixture and diamond layers containing diamond particles that are arranged in a set pattern; shaping the green compounds into ring segments (62, 63) under the effect of pressure; and joining the ring segments (62, 63) in a circular manner and sintering same under the effect of heat so as to obtain a continuous drill ring (51).

Description

Method for producing a closed drill ring for a core bit Technical field

The present invention relates to a method for producing a closed drill ring for a core bit according to the preamble of claim 1.

State of the art

For diamond tools designed as coring bits, a distinction is made between core drill bits with a closed drill ring and segmented core drill bits with individual cutting segments. Core bits consist of a machining section, a cylindrical drill shaft and a receiving section with insertion end. The core bit is fastened via the insertion end in the tool holder of a core drilling machine and driven in drilling operation by the core drilling machine about an axis of rotation. Closed drill rings are manufactured from a powder mixture with randomly distributed diamond particles. The powder mixture is filled into a mold and pressed into a green part; the green part is sintered under temperature and pressure to form a closed drill ring. US 5,316,416 discloses the construction of closed drilling rings, which have good removal properties over the entire height of the drill ring. The drill rings have a plurality of upper slots and lower slots distributed along the circumferential direction of the drill rings. The upper slots extend over half the height of the drill rings and open into the drilling shaft facing away from the processing surface of the drill rings. The lower slots are respectively arranged between the upper slots along the circumferential direction of the drill rings and open into the attachment surface of the drill rings facing the drill shaft. The upper and lower slots overlap in the height of the drill rings. The distribution of the upper and lower slots over the entire height of the drill rings, a cooling and rinsing fluid is transported over the entire service life of the drill ring to the processing site and removed material is removed from the drilling area. In the production of cutting segments for segmented core drill bits, processes have been established in the professional field, in which the diamond particles in a predetermined Setzmuster be arranged. A green part is built up in layers from powder layers containing a powder mixture and diamond layers with diamond particles, which are arranged in a setting pattern, and then sintered under temperature and pressure to the cutting segment. The cutting segments are arranged along a circumferential direction of the cylindrical drill shank and welded to the drill shank, soldered and fastened in some other way. The cutting speed achievable with a segmented core bit depends largely on the arrangement of the diamonds in the cutting segment. With the layered structure, the arrangement of the diamond particles can be influenced by the number of diamond layers, the distance between the diamond layers and the size of the diamond particles.

Presentation of the invention

The object of the present invention is to apply the technology of the set diamond particles to closed drill rings and to increase the machining quality achievable with the drilling rings thus produced. This object is achieved in the aforementioned method for producing a closed drill ring for a core bit according to the invention by the features of independent claim 1. Advantageous developments are specified in the dependent claims.

The method according to the invention for producing a closed drill ring comprises the steps:

^■ at least two green parts are built up in layers in a construction direction by successive application of powder layers of a powder mixture and diamond layers with diamond particles, which are arranged in a setting pattern, between a bottom side and a top side,

■ the green parts are converted under pressure to ring sections and

^■ The ring sections are assembled in a ring shape and sintered under the influence of temperature to form a closed drill ring.

The method according to the invention comprises three process sections which use different technologies. In the first stage of the process, several green parts are built up layer by layer from powder layers containing a powder mixture and diamond layers with diamond particles. The term "powder mixture" includes fine-grained powder mixtures and granulated powder mixtures; The use of granulated powder mixtures is a prerequisite for volumetric cold pressing. As a powder mixture iron, cobalt and / or bronze powders can be used; By mixing in additives, such as tungsten carbide, the properties of the drill rings (wear resistance, durability, cutting ability) can be influenced. In addition, the composition of the powder mixture has an influence on the sintering temperature. The term "diamond particles" includes individual diamond particles as well as coated or coated diamond particles.

The green parts have, according to the layered structure on the geometric shape of a straight prism with a polygonal base. The prismatic green parts are formed in the second process section under pressure to form ring sections. The reshaping of the green parts takes place at temperatures which are below the melting temperature of the powder mixture. In the third process section, the ring sections are assembled in a ring and sintered under the influence of temperature to form a closed drill ring. During sintering of the ring sections, on the one hand there is a compression of the individual ring sections and, on the other hand, a connection between adjacent ring sections.

Cold forming, hot pressing and similar processes are suitable as forming processes. In cold pressing, a green part is brought under a high pressure in the predetermined shape. In a cold press, the material is indeed heated, but the transformation takes place in a temperature range in which no recrystallization occurs; The material deforms without the strength decreasing significantly. In hot pressing, which is also referred to as drop forging, a green part is brought under its high pressure and the addition of heat in its final form. In addition to the shape, the forging changes its material structure; it gets stronger and thus gets a denser texture and a homogeneous surface.

Sintering is a process for the production of materials in which a powder or a green part (pressed powder) are heated to temperatures below the melting temperature in order to increase the strength by bonding the individual powder particles. The sintering process takes place in three stages, in which the porosity and the volume of the green part are significantly reduced. In the first stage of sintering, only a densification of the green part takes place, whereas in the second stage the open porosity is significantly reduced. The strength of the sintered bodies is based on the sintered compounds formed in the third stage (deposits between the powder particles), which are produced by surface diffusion between the powder particles. Hot pressing is a special sintering process that uses external pressure in addition to temperature.

The drill ring is not constructed in the method according to the invention as a closed drill ring, but is composed of two or more ring sections, which are characterized by be connected. In the layered construction of the green parts, the known technologies are used in the manufacture of cutting segments for segmented core bits.

In a preferred variant of the method, the drill ring is constructed from a number of n, n> 1 first green parts, which are formed into first ring sections, and n second green sections, which are formed into second ring sections, wherein the first and second ring sections along a Circumferential direction of the drill ring are arranged alternately one behind the other. The production of the drill ring from the first and second green parts enables the adaptation of the drill ring to different substrates to be machined. For example, in core drilling in concrete materials with embedded reinforcing bars, which are also referred to as reinforced concrete materials, a drill ring encounters different substrates in the form of concrete and reinforcing bars.

Particularly preferably, the first ring sections are constructed from a first powder mixture and first diamond particles and the second ring sections are built up from a second powder mixture and second diamond particles. The adjustment of the drill ring to the substrate to be processed can be done by selecting the powder mixture and the choice of diamond particles. With the powder mixture, the composition of the materials can be varied; For the diamond particles, the mean diamond diameter, the diamond distribution and the number of diamond particles can be varied. In an alternative preferred variant of the method, the drill ring is constructed from a number of 2n, n> 1 equal green parts, n green parts under pressure with a convex curvature to first ring sections and n green parts under pressure with a concave curvature to second ring sections are formed. Through the use of the same green parts, the expenditure on equipment in the layered structure of the green parts can be reduced; only one powder mixture and one kind of diamond particles are needed.

Particularly preferably, the upper side of the green parts is arranged on the outer side in the case of the first ring sections and on the inner side in the case of the second annular sections, wherein the first and second annular sections are arranged alternately one after the other along a circumferential direction of the drill ring. Due to the different curvature of the ring sections two different ring sections can be made from the same green parts. The green parts have on the upper side a diamond layer which is arranged at the first annular sections on the outer lateral surface and in the second annular sections on the inner lateral surface. Particularly preferably, the number of diamond layers and the size of the diamond particles are adjusted so that the average diamond diameter of the diamond particles is at least 45% of the quotient of drill ring width and number of diamond layers. For the machining of reinforced concrete materials, it has proven to be advantageous if the circular removal paths that describe the diamond particles during processing, as close as possible to each other and the reinforcing bars are almost completely removed from the diamond particles. The number of removal paths that produce the diamond particles during machining can be doubled by the alternating arrangement with the same number of diamond particles. The green parts have, according to the layered structure on the geometric shape of a straight prism with a polygonal base. As polygonal bases are rectangular bases, pentagonal bases and hexagonal bases.

In a first variant, the green parts are built up from powder layers with rectangular bases. The rectangular base is the simplest geometry to make drill rings from multiple ring sections. The ring sections are connected at the side edges with the adjacent ring sections.

In a second variant, the green parts are built up from powder layers with pentagonal bases, wherein the bases have a rectangle and a trapezoid with two right interior angles. In the area of the inclined trapezoid leg, a water slot is created during sintering with the adjacent ring section. With such a pentagonal base area, a number of n water slots is produced in a drill ring with 2n, n> 1 ring sections.

In a third variant, the green parts are built up of powder layers with hexagonal bases, wherein the bases have a rectangle and an isosceles trapezoid. In the area of the inclined trapezoidal legs, water slots are created during sintering with the adjacent ring sections. With such a hexagonal base surface, a number of n water slots is produced in a drill ring with n, n> 2 ring sections.

Particularly preferably, the height of the trapezoid is set between 1/3 and 5/6 of the total height of the green part. For drill rings that are welded to the drill shank, the connection area is set up without diamonds and is unsuitable for machining. For the treatment of substrates, the matrix zone provided with diamond particles, which represents approximately 5/6 of the total height of the green part, is suitable. Particularly preferably, the height of the trapezoid is set to 2/3 of the total height of the green part. With a share of 2/3 of the total height, sufficient strength of the finished drill ring can be ensured. During machining with the drill ring, coolant must be transported to the processing site; Therefore, the water slots are formed in the drill ring as long as possible. In a preferred development, the ring sections are subjected to a temperature and pressure effect during sintering. In sintering processes with temperature and pressure, such as hot pressing, the sintering proceeds faster and at a lower temperature than in sintering without pressure, such as free sintering. Since thermal diamond damage already occurs at 600 ° C, a lower sintering temperature can be a qualitative advantage.

Particularly preferably, the ring sections are subjected to an additional external shaping by the pressure effect during sintering. For the treatment of different substrates, special roof forms have proven to be suitable. These roof shapes can be generated by pressure during sintering.

embodiments

Embodiments of the invention are described below with reference to the drawing. This is not necessarily to scale the embodiments, but the drawing, where appropriate for explanation, executed in a schematic and / or slightly distorted form. With regard to additions to the teachings directly recognizable from the drawing reference is made to the relevant prior art. It should be noted that various modifications and changes may be made in the form and detail of an embodiment without departing from the general idea of the invention. The features of the invention disclosed in the description, the drawing and the claims can be essential both individually and in any combination for the development of the invention. In addition, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of the invention is not limited to the exact form or detail of the preferred embodiment shown and described below or limited to an article that would be limited in comparison with the subject matter claimed in the claims. For given design ranges, values lying within the specified limits should also be disclosed as limit values and be arbitrarily usable and claimable. For simplicity, the same reference numerals are used below for identical or similar parts or parts with identical or similar function. Show it: FIG. 1 a core bit consisting of a drill ring, a cylindrical

Drill stem and a receiving portion;

FIGS. 2A-C show a first embodiment of a drill ring according to the invention, which is constructed from four ring sections, in a three-dimensional representation (FIG. 2A), in a cross section perpendicular to the cylinder axis of the drill ring

(FIG.2B) and in a detail enlargement (FIG.2C);

FIG. 3 shows a second embodiment of a drill ring according to the invention, which is constructed from four ring sections with water slots;

FIGS. 4A-D show the manufacture of the drill ring of FIG. 4), wherein two green parts are converted into concave first ring sections and two green parts are converted into convex second annular sections (FIG. 4B), the first and second annular sections being arranged alternately behind one another along a circumferential direction (FIG 4C) and under temperature and pressure to a closed drill ring are connected (FIG 4D). and

FIGS. 5A-C green parts with a rectangular base (FIG.5A), a pentagonal one

Base (Figure 5B) and a hexagonal base (Figure 5C).

FIG. 1 shows a core bit 10 with a drill ring 11, a cylindrical drill shaft 12 and a receiving section 13 with insertion end 14. The core bit 10 is fastened via the insertion end 14 in the tool receptacle of a core drilling device and driven by the core drilling device in a rotational direction 15 about a rotation axis 16 during drilling operation , wherein the axis of rotation 16 is coaxial with the cylinder axis of the core bit 10.

The drill ring 1 1 is welded to the drill shaft 12, soldered, screwed or fastened in another suitable manner of attachment to the drill shaft 12. In order to weld the drill ring 1 1 with the drill shank 12, the connection area between drill ring 1 1 and drill shank 12 must be constructed of a weldable material and must not contain diamond particles, since diamond particles are not weldable.

FIGS. 2A-C show a first embodiment of a drill ring 21 according to the invention, which is composed of several ring sections and the drill ring 1 1 of 10 Kernbohrkröne of FIG. 1 can replace. In this case, FIG. 2A shows the drill ring 21 in a three-dimensional representation, FIG. 2B shows the drill ring 21 in a cross section perpendicular to the axis of rotation 16 and FIG. FIG. 2C shows a section from the cross section of FIG. 2B in the connection area between two ring sections. The drill ring 21 is composed of four ring sections which are connected to one another at the side edges and form a closed ring in the circumferential direction (FIG. 2A). The ring sections of the drill ring 21 can be divided into two first ring sections 22.1, 22.2 and two second ring sections 23.1, 23.2, which are arranged alternately one after the other along the circumferential direction of the drill ring 21. The first ring sections 22.1, 22.2 consist of a first powder mixture 24 and first diamond particles 25 and the second ring sections 23.1, 23.2 consist of a second powder mixture 26 and second diamond particles 27 (FIG. 2B).

FIG. FIG. 2C shows a detail from the cross section of FIG. 2B in the connection area between see the first ring portion 22.1 and the second ring portion 23.1. The first ring section 22. 1 is constructed from a number of ITH powder layers of the first powder mixture 24 and with diamond layers of the first diamond particles 25. The second ring section 23.1 is made up of a number of m ₂ powder layers of the second powder mixture 26 and m ₂ diamond layers of the second diamond particles 27. In the embodiment of FIG. 2, the first ring section 22.1 rrn = 3 powder layers 28.1, 29.1, 30.1 and rrn = 3 diamond layers 32.1, 33.1, 34.1 and the second ring section 23.1 m ₂ = 3 powder layers 35.1, 36.1, 37.1 and m ₂ = 3 diamond layers 38.1, 39.1, 40.1.

The first diamond particles 25 of the diamond layers 32.1 to 34.1 are arranged on three circular first removal paths 42.1, 43.1, 44.1 with different first radii of curvature RH, i = 1, 2, 3. The second diamond particles 27 of the diamond layers 38.1 -40.1 are arranged on three circular second removal paths 45.1, 46.1, 47.1 with different second radii of curvature R ₂ , i = 1, 2, 3. The choice of materials for the first and second powder mixtures 24, 26, the selection of the diamond distribution and size for the first and second diamond particles 25, 27 and the number m-ι, m _{2 of} the diamond layers and Abtrag paths allow the adaptation of the drill ring 21 to different substrates to be processed.

The ring sections 22.1, 22.2, 23.1, 23.2 are constructed in layers of three powder layers and three diamond layers. In the layered structure, the powder mixture is filled in a die and forms the first powder layer. The diamond particles are placed in a setting pattern as a first diamond layer on or in the first powder layer. In order to densify the layer structure, an intermediate pressing can take place after the diamond particles have been placed. Subsequently, the powder mixture is filled in the die and forms the second powder layer. The diamond particles are placed in a setting pattern as a second diamond layer on or in the second powder layer. This process is repeated until the desired structural height of the green part is reached. The last layer is a diamond layer. FIG. 3 shows a second embodiment of a drill ring 51 according to the invention, which consists of four ring sections and can replace the drill ring 1 1 of the core bit 10. Between the ring sections four water slots 52.1, 52.2, 52.3, 52.4 are formed, via which a cooling liquid is transported to the processing site. The ring sections are arranged so that the drill ring 51 on the inside 53 and on the outside 54 alternately has a diamond-studded area 55 and a diamond-free area 56.

The water slots 52.1 -52.4 extend over a height of about 2/3 of the total height of the drill ring 51. To ensure the functionality of the drill ring 51, when the water slots 52.1 -52.4 are removed, two ring sections have a bore 57.1, 57.2 on the cooling liquid is transported to the processing site.

FIGS. 4A-D show the production of the drill ring 51 from four identical green parts 61 with a hexagonal base (FIG. 4A). Two green parts 61 are formed into concave first ring portions 62 and two green parts 61 are formed into convex second ring portions 63 (FIG.4B). The first and second ring sections 62, 63 are alternately arranged one behind the other along a circumferential direction of the drill ring 51 (FIG. 4C) and sintered under temperature and pressure into a closed drill ring (FIG.

FIG. FIG. 4A shows the structure of the green part 61 which has been made layer by layer from powder layers of a powder mixture 64 and diamond layers of diamond particles 65. The green part 61 consists of a connection region 66, which is also referred to as a foot zone, and a processing region 67, which is also referred to as a matrix zone. The connection region 66 and the processing region 67 can be built together in layers, with no diamond particles 65 being set in the connection region. Alternatively, the connection region can be produced as a separate region and connected to the processing region during sintering. The base of the green parts 61 is hexagonal and consists of a rectangle 68 and an adjacent isosceles trapezium 69, wherein the connection region 66 of the green part 61 is in the rectangle 68. In the area of the trapezoidal limbs, the water slots 52.1 - 52.4 are formed during sintering by additional pressure action, via which cooling liquid is transported to the processing site. The height h of the trapezium 69 in the green part determines the height of the water slots 52.1 -52.4. In the exemplary embodiment, the height h of the trapezoid 69 corresponds to half the total height H of the green part 61.

FIG. 4B shows the first ring portion 62 formed from the green portion 61 of FIG. 4A was generated under pressure with a convex curvature, and the second ring portion 63 formed from the green part 61 of FIG. 4A under pressure with a concave Curvature was generated. In the first ring portion 62, the top of the green part 61, which is formed as a diamond layer, on the outside 54 and the second ring portion 63, the top of the green part 61 is disposed on the inside 53.

The first ring section 62 has a first and a second side edge 71, 72 which, when sintered, are connected to a first and a second side edge 73, 74 of the second ring section 63. In this case, the first side edge 71 of the first ring section 62 is connected to the second side edge 74 of the second ring section 63 and the second side edge 72 of the first ring section 62 is connected to the first side edge 73 of the second ring section 63. When drilling ring 51 with two first and second ring sections 62.1, 62.2, 63.1, 63.2 respectively the first and second side edges of the adjacent ring sections are connected to each other.

FIG. 4C shows the first ring sections 62.1, 62.2 and second ring sections 63.1, 63.2, which are arranged alternately one behind the other along a circumferential direction of the drill ring 51. The ring sections 62.1, 63.1, 62.2, 63.2 form a closed drill ring and are in the in FIG. 4C further processed in a hot press. FIG. 4D shows the closed drill ring after hot pressing. When hot pressing the ring sections 62.1, 63.1, 62.2, 63.2 subjected to a temperature and pressure. The effect of the temperature ensures that the powder mixture in the ring sections is sintered and the ring sections are joined together at the side edges. By pressure in the axial direction, i. parallel to the axis of rotation of the drill ring, there is a compression of the ring sections, which leads to a compression of the ring sections. The hot pressing takes place in a die, which determines the final shape of the drill ring.

A drill ring is constructed in the process of the invention from several green parts, which are formed into ring sections and sintered into a closed drill ring; polygonal bases are suitable as geometry for the green parts. FIGS. 5A-C show green parts 81 having a rectangular base (FIG.5A), green parts 82 having a pentagonal base (FIG.5B), and green parts 83 having a hexagonal base (FIG.5C). The rectangular base 84 of the green parts 81 represents the simplest geometry to

To produce drill rings from several ring sections. In the embodiment of FIG. 5A, three equal green parts 81.1, 81 .2, 81 .3 are used to make a closed drill ring. The pentagonal base of the green parts 82 can be divided into a rectangle 85 and a trapezoid 86 with two right interior angles. In the area of the inclined trapezoid leg, a water slot 87 is produced during sintering with the adjacent ring section. With such a pentagonal base area, a number of n water slots 87 are produced in a drill ring with 2n, n> 1 ring sections.

The hexagonal base of the green parts 83 can be divided into a rectangle 88 and an isosceles trapezium 89. In the region of the inclined trapezoidal legs water slots 90 are generated during sintering with the adjacent ring sections. With such a hexagonal base area, a number of n water slots 90 are generated in a drill ring with n, n> 2 ring sections.

Claims

claims

1 . Method for producing a closed drill ring (21; 51) for a core bit (10), comprising the steps of:

^■ at least two green parts (61, 81, 82, 83) are formed in a construction direction by successive application of powder layers (28, 29, 30, 35, 36, 37) of a powder mixture (24, 26, 64) and diamond layers (32 , 33, 34, 38, 39, 40) with diamond particles (25, 27; 65), which are arranged in a setting pattern, constructed in layers between a bottom side and a top side,

^■ the green parts (61, 81, 82, 83) are deformed under pressure to ring sections (22, 23, 62, 63) and

^■ The ring sections (22, 23, 62, 63) are assembled in a ring shape and sintered under the influence of temperature to form a closed drill ring (21, 51).

2. The method according to claim 1, characterized in that the drill ring (21) from a number of n, n> 1 first green parts, the first ring sections (22.1, 22.2) are formed umgege, and n second green parts, the second Ring segments (23.1, 23.2) are formed, is constructed, wherein the first and second ring portions (22.1, 22.2, 23.1, 23.2) along a circumferential direction of the drill ring (21) are arranged alternately one behind the other.

3. The method according to claim 2, characterized in that the first ring sections (22.1, 22.2) of a first powder mixture (24) and first diamond particles (25) and the second ring sections (23.1, 23.2) of a second powder mixture (26) and second Diamond particles (27) are constructed.

4. The method according to claim 1, characterized in that the drill ring (51) of a number of 2n, n> 1 same green parts (61) is constructed, wherein n green parts (61) under pressure with a convex curvature to first ring sections (62.1,

62.2) and n green parts (61) under pressure with a concave curvature to second ring sections (63.1, 63.2) are formed.

5. The method according to claim 4, characterized in that arranged the upper side of the green parts (61) in the first ring sections (62.1, 62.2) on the outside (54) and in the second ring sections (63.1, 63.2) on the inside (53) is, wherein the first and second ring portions (62.1, 62.2, 63.1, 63.2) along a circumferential direction of the drill ring (51) are arranged alternately one behind the other.

6. The method according to claim 5, characterized in that the number of diamond layers (mi, m ₂ ) and the size of the diamond particles (25, 27, 65) are adjusted so that the average diamond diameter of the diamond particles (25, 27, 65) at least 45% of the quotient of the width of the drill ring (21; 51) and the number of diamond layers (rrn, m ₂ ).

7. The method according to any one of claims 1 to 6, characterized in that the green parts (81) of powder layers with rectangular bases (84) are constructed.

8. The method according to any one of claims 1 to 6, characterized in that the green parts (82) are constructed of powder layers with pentagonal bases, wherein the bases have a rectangle (85) and a trapezoid (86) with two right interior angles.

9. The method according to any one of claims 1 to 6, characterized in that the green parts (83) are constructed of powder layers with hexagonal bases, wherein the base surfaces have a rectangle (88) and an isosceles trapezoid (89).

10. The method according to any one of claims 8 to 9, characterized in that the height of the trapezoid (86, 89) between 1/3 and 5/6 of the total height (H) of the green part (82, 83) is adjusted.

1 1. Method according to claim 1, characterized in that the ring sections (22, 23;

62, 63) are subjected to a temperature and pressure during sintering.

12. The method according to claim 1 1, characterized in that the ring sections (62, 63) are subjected by the pressure effect during sintering of an additional outer shaping.