DE2145051A1 - Diamond core drilling tool - Google Patents

Description

2Η505Ί

PATH NTANWALTY

ing. Jt. WOOD

P9 A UO 8 HU K G W. 5 ^ 7

1*

Augsburg, September 7th, 1971

Westinghouse Electric Corporation, Westinghouse Building, Gateway Center, Pittsburgh, Allegheny County, Pennsylvania 15 222, V.St.A.

and

Hoffmann Diamond Products, Inc., 108 Cedar Street, Punxsutawney, Pennsylvania 15 767, V.St.A.

Diamond core drilling tool

The invention relates to diamond core drilling tools.

Diamond core drilling tools for rotary drilling are used in geological exploration and exploitation from reservoirs for taking drill core samples

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used at different depths. Diamond core drilling tools are also used for drilling blast holes in other hard Materials used in which other drill bits are ineffective or uneconomical.

In hard pouring rock, such as instrusion basalt from the quarries of Dresser in Wisconsin, V.St.A., which has a rated compressive strength

of 3020 kp / ctn and a hardness of 79 Shore, a service life of about 9 m / drill bit is considered normal, when working with water flushing to remove the cuttings.

The diamond core drilling tools that are used for rotating Drilling in rock are used, follow the standard sizes of the American in their dimensions Diamond Core Drill Manufacturer's Association, however, the diamond sizes used give way to diamond arrangements and the diamond orientation are very different from each other.

Drilling tool manufacturers bring drilling tools of their own design onto the market and usually make them produces a significant number of deviating designs for drilling contractors. These deviating constructions

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are based on the experience of the drilling tool manufacturer and the drilling contractor or on data that is based on little scientifically obtained.

The drilling work that is carried out with these drilling tools often only depends on the Judgment of the drilling specialist.

The drilling industry is generally based mainly on the cost per meter of borehole depth, according to the motto: the cheaper the drilling tool, the cheaper the drill hole. With such changeable such as drilling tools designed and executed on the basis of rather unscientific data Drilling work can have very negative financial consequences when drilling a borehole, if that Drilling tool and the judgment of the drilling expert do justice to the rock formation in question.

In addition, because of the long training period, which is up to 10 years, before a drilling specialist has sufficient experience, the number of trained drilling specialists is very limited. In addition, often in remote areas and under unfavorable climatic conditions that also pay

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is pretty bad and that geological drilling work is always interrupted by the onset of winter.

The drilling and other machining industries have reluctantly admitted that the rotating Drilling with diamond core drilling tools without cooling the diamonds and without removing the cuttings Liquid or gas. There is many applications in which drilling with dry cuttings removal is preferable. from Examples of such applications are: The dismantling of decorative stones, in which of liquids resulting stains cause additional finishing costs, or masonry where the immediate Wet drilling is not permitted in the vicinity, as in hotels or hospitals, as well as with certain manufacturing processes, in which introduced impurities affect the end use of the material, such as Sole material and other composite materials, etc.

The invention aims to achieve the object of improving a diamond core drilling tool in such a way that it has a longer service life for both dry drilling and wet drilling.

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In terms of the solution to this problem, the invention includes a diamond core drilling tool which is characterized by a cylindrical drill bit made of a metallic base material with a plurality of circumferentially distributed cutting surfaces, which are aligned in the manner of a snowplow and which are separated from each other by cuttings discharge grooves formed in an annular, semicircular cutting surface of the drill bit, wherein the circumferential areas of the drill bit at the transition from the annular cutting surface to the inner and outer cylindrical part are rounded with a smaller radius than in the area in between, furthermore by a coaxial, cylindrical drill part attached to the drill bit with spiral flutes which form further cuttings removal grooves by a large number of dodecahedral diamonds of the AAAA class, the size of which is in a range from 18 diamonds / carat to 22 diamonds / carat and which are embedded in the base material in such a way that ß each defect-free, right-angled pyramid tip areas of the same protrude from the base material by a distance of 0.358 mm ί 0.0076 mm, the diamonds with their surfaces of maximum hardness and with a negative ^w chip ^K angle are aligned to the direction of the rotary cutting of the drilling tool, and taking some of the diamonds

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are arranged as clearing stones on the inner and outer cylindrical parts of the drill bit and other diamonds are arranged as cutting stones on the annular cutting surface and on the peripheral areas in such a way that the protruding cutting tips of the cutting diamonds are concentric, each an equal radial distance of 0.25 mm t lie 0.0025 mm of each other with circular lines and that the axes of the diamond tips on the annular cutting surface lie in vertical planes parallel to the axis of the drilling tool, while the axes of the diamond tips on the rounded peripheral areas lie in planes perpendicular to the tangents on these peripheral areas.

An embodiment of the invention is illustrated in the drawings and will be described below described in more detail. Show it:

Pig. I a side view of one

Diamond core drilling tool according to the invention,

Fig. 2 is a longitudinal section through the

shown in Fig. 1 diamond core drilling tool according to the invention,

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Pig. 5 is a plan view of the cutter

area of the in Pig. I illustrated diamond core drilling tool the invention in the direction of an arrow III,

4 shows a section through a son's oath

segment of the diamond core drilling tool along the line IV-IV in Fig. 3,

5 shows a preferred one in plan view

Type of arrangement of the embedded in the drill bit of the drilling tool according to the invention Diamonds, and

Fig. 6 · a section through the in

Fig. 5 shown diamonds along the line VI-VI.

The diamond core drilling tool shown in FIGS according to the invention is constructed according to the following aspects:

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Class of diamonds:

There are exclusively or almost exclusively diamonds d used, at least in one selected right-angled pyramid tip area with an included angle of 110 ° to 120 ° free of surface defects and subsurface defects. These diamonds are d with the help of a Microscope under commercial AAAA stones, such as South African borts, which too the American names "Creams", "4a", "Quadruple A", "Special", "Special Rounds", "Gem" and Wear "Gem-Grade" selected. "Brown Premier" stones can be used as well.

Crystal shape of the diamonds:

It is exclusively or almost exclusively the rhombic dodecahedron crystal shape instead of the octahedron shape used.

Size of diamonds:

There are exclusively or almost exclusively diamonds with a nominal size of 20 stones / carat

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used within a size range of 18 stones / carat to 22 stones / carat.

Embedding the diamonds in the base material;

The diamonds d with the selected nominal size of 20 stones / carat each protrude by an average of 0.38 mm from the base material m so that these diamonds are at least two-thirds or more of their length in are firmly anchored in the base material of the drilling tool and still have sufficient leeway for conveying them through hard cuttings between the cutting tip part t of the diamond protruding part and the The base material remains, see FIG. 6.

Orientation of the diamonds:

The diamonds d are arranged as shown in FIGS. 5 and 6 each so that a surface its cutting tip area forming a right-angled pyramid with respect to the direction of movement pointing to the front and that with respect to this direction of movement a negative one, i.e., pointing backwards "Span" angle of 4 1/2 ° is formed.

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Arrangement of diamonds;

The protruding tips of the cutting surface and circumferential diamonds, FIG. 6, are arranged according to a pattern which is based on circular lines, ie imaginary lines on the drilling tool cutting surface at a certain radial distance from the drilling tool center. The reference numbers of the diamonds d in FIGS. 3 and 4 indicate the circular lines on which the tips of the diamonds in question lie, specifically in numerical order from the inner diameter ID to the outer diameter AD. The circular lines must be less than 1.2 mm apart, because the 20 stones / carat diamonds at the level of the base material have approximately this width. A distance of 0.25 mm ί 0.0025 mm between the circular lines appears optimal and allows for better removal of drill cuttings, since the resulting cut notch is smoother. For a tool size with an outside diameter of 49.6 mm and an inside diameter of 35 mm, yj circular lines are used. One to three diamonds / circular line are permitted, with two diamonds / circular line being selected for the cutting surface and three or four diamonds / circular line in the circumferential circular line. The diamonds are each in radial

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and negatively curved rows arranged. The individual diamonds form together with the diamonds in the outer ones Rows of spirals. These spirals help guide the cuttings away over the cutting surface towards the AD range. The cutting tip axes of the cutting face diamonds on the semicircular, ring-shaped Cutting surface with a radius of 6.95 mm (Fig. 6), lie in vertical planes parallel to the axis of rotation of the drilling tool, while the cutting tip axes of the Circumferential diamonds in a plane perpendicular to the tangent which are close to those under a radius of 1.27 mm i 0.13 mm curved parts of the drilling tool to 'the Transitions from the semi-flat, annular cutting surface is applied to the parts of the drilling tool with the inner diameter ID and the outer diameter AD.

Cuttings removal:

The cuttings removal grooves g in the cutting surface are negatively curved, have a length of about 7 * 72 mm between the OD circumference and the ID circumference and are about 1.6 mm deep. These grooves are so far around guided around the OD circumference until the drill spiral flutes meet in the corresponding sectors. ID replacement

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areas are around the top ID edge of the drill bit out and form port settings of alternating cuttings detachment areas the cutting surface.

Inlet openings of the spiral grooves for the removal of cuttings i

Three main spiral groove inlet openings lead from the AD cuttings evacuation grooves in the drill bit to three upward spiral grooves. Five more entrances per spiral groove are made by other AD cuttings Guide grooves formed.

Spiral grooves for removing cuttings;

While three or six spiral drill flutes work equally well, they will simplify manufacturing however, three spiral grooves are preferred. A spiral flute angle of 15 ° at speeds of <500 rpm, is used to move the cuttings created by the drilling tool in hard rock formations. The drill spiral flutes are each 1.27 mm deep and 8.9 mm wide. The outer diameter AD on the back surfaces of the spiral groove flanks is only 0.8 mm smaller than the nominal outer diameter AD over an axial distance of several centimeters

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the drill bit to help stabilize the drilling tool in the borehole. The outside diameter is on the other hand AD of the spiral groove flanks above this area by 1.02 mm smaller than the outer diameter AD the drill bit.

Basic material of the drill bit;

A base material made of cemented tungsten carbide powder with a silver-based alloy, which is a "T-4" material manufactured by Kennametal Corporation of Latrobe, Pa. is equivalent to "T-4" proved to be sufficiently stable and wear-resistant for anchoring the diamonds in the drilling tool.

A drilling tool with the outside diameter of 49 * 6 mm and the inside diameter of 35 mm, which has been manufactured according to the above information, has the following performance specifications and operating recommendations for the operating parameters listed below:

Feed force:

To reduce diamond breakage and to

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Increase in tool life at high penetration depth / revolution is a nominal drilling pressure of 13 * 6 kp Feed force has been set for each pressure-absorbing diamond. If there is a possibility that while drilling hard inclusions, such as quartz, are encountered, the feed force is reduced to about 7.25 kp per pressure-transmitting diamond limited. The feed force / pressure transmitting Diamond is defined as the total feed force on the drilling tool divided. by the sum of the cutting surface stones and two thirds of the peripheral stones. When running in the drill and at lower drilling pressures are used for softer rock formations.

Drill speed:

The drill speed (rpm) represents a compromise, because high speeds result in high drilling tool temperatures, a relatively rapid diamond wear and chatter while at low rates Speeds low temperatures, longer tool life, less chatter and lower penetration speeds result.

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For drilling tools with an outside diameter of 49.6 mm and an inside diameter of 35 mm, a Speed of 375 rpm, when drilling into basalt from the Dresser quarries mentioned at the beginning represent an optimum.

Running-in of the drilling tool:

When drilling in hard rock, the initially high penetration speed decreases in a range between 0.3 m and 2.4 m until a speed is reached at which in a small range of the feed force is being drilled during most of the tool life. It has been shown that between diamonds protruding differently from the base material and the high drilling speed Relationship exists. In order to compensate for the different protrusions of the diamonds, the drilling tool must be included a speed which is lower than the normal drilling speed, and operated with a feed force which does not allow rattling until the drilling speed has stabilized.

Rattle;

The chatter limits the tool life,

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as it promotes breakage and wear of the diamond. The chatter is vertical and as a combination horizontal oscillatory movements due to a variety of causes on the drilling tool diamond be exercised. The chatter can be caused by excessive speed, insufficient feed force, insufficient removal of drillings, incomplete running-in and eccentricities of the drilling tool are caused. It lets through suitable running-in of the drilling tool by changing the speed and / or the feed force and by optimizing the gap sizes in the drilling tool design for the anticipated penetration speeds as well as through Mastering partial filling of the spiral grooves for lateral stabilization purposes.

Penetration / revolution:

The penetration / revolution is the advance of the drilling tool per revolution into and into the material is referred to as "bite". In addition to the feed force, the bite depends on the number of diamonds / circular line and influenced by the number of circular lines themselves. For the drilling tool with an outer diameter of 49.6 mm and the inner diameter of 35 mm have 2 diamonds / Circle line and j57 circle lines spaced apart from each other 0.25 mm between the circular lines proved to be the optimum.

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With two diamonds / circle and at the optimal drilling speed of 0.15 mm / revolution for basalt the depth of cut per diamond is 0.076 mm per revolution.

Sample material changes;

Material changes, for example with regard to microstructure, hardness, compressive strength, as well as fractures, Cavitations and new layers have a detrimental effect on the drilling diamonds. To reduce diamond breakage should the diamonds with a maximum feed force of 7.25 kp to 13.6 kp per pressure-transmitting Diamond are loaded, the higher values being selected with increasing aging of the drilling tool This increase in thrust is based on a maximum penetration speed which is suitable for the type of material being drilled has been set. In Dresser basalt, 0.15 mm / rev is the optimum for the maximum drilling speed .

The design of the mold for the drilling tool as well as the drilling tool manufacturing process can do that Making it easier to achieve the desired drilling tool dimensions:

For a three-part mold (not shown)

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and for the mold inserts, which were used for the production of cuttings removal grooves and the like. Is a hard carbon with a smooth surface has been used.

Each element of the form was previously made to * o'oOO mm precisely machined.

The form was made in three parts in order to drill the diamond insert eyes or, -, - indentations facilitate.

The eye markings were made to a certain depth and to the exact rake angle diamond orientation Drilled on a milling machine equipped with a dividing head that indexed through an angle allowed for 5 minutes.

The countersink used to bore the eyes had an included angle at which the included Angle of the selected diamond point and that of the selected stones in the size range of 18 stones / carat to 22 stones / carat expected angle tolerances were taken into account.

By a skilled diamond setter, the

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Stones are carefully inserted so that each diamond in the finished drilling tool has a suitable one Cutting surface shows and that each diamond tip rests on the base of its holding eye.

The remaining operations in the drilling tool production were carried out with unusual care, to avoid disturbing the position of the inserted diamonds.

The core tube supporting the drill bit was machined from FM-Invar rod material. Invar was used because of its stable thermal properties. Since the outer diameter of the core tube is attached to the incorporated For the reasons mentioned above, spiral groove flanks by only 0.158 mm may be smaller than the nominal outer diameter of the drill bit, a core tube, which could result the drilling heat expands too much, causing plague eating of the drilling tool in the borehole.

The drilling tool was machined to a maximum deviation of 0.025 mm to avoid chattering due to Avoid eccentricities.

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Claims (4)

J0 2U5051 claims; 1. Diamond core drilling tool, characterized by a cylindrical drill bit made of a metallic base material (m) with a multiplicity of circumferentially distributed partial cutting surfaces aligned like a snowplow, which are separated from one another by cuttings discharge grooves formed in an annular, semicircular cutting surface of the drill bit, the peripheral areas of the drill bit at the transition from the ring-shaped cutting surface are each rounded on the inner and outer cylindrical part with a smaller radius than in the area in between, further by a coaxial, cylindrical drill part fastened to the drill bit with spiral flutes, which form further cuttings removal grooves, further by a multitude of dodecahedral diamonds ( d) Class AAAA, the size of which is in a range from 18 diamonds / carat to 22 diamonds / carat and which are embedded in the base material in such a way that each fault-free right-angled pyramid tip regions de They protrude from the base material by a distance of 0.38 mm - 0.0076 mm, the diamonds with their surfaces of maximum hardness and with a negative "chip" angle being oriented towards the direction of the rotary cutting of the drilling tool, and - 20 - 209 »/ * 8/0553 2H5051 Some of the diamonds are arranged as clearing stones on the inner and outer cylindrical parts of the drill bit and other diamonds are arranged as cutting stones on the annular cutting surface and on the peripheral areas in such a way that the protruding cutting tips (t) of the cutting diamonds are concentric, each one the same radial distance of 0.25 mm - 0.0025 mm from each other and that the axes of the diamond tips on the ring-shaped cutting surface lie in vertical planes parallel to the axis of the drilling tool, while the axes of the diamond tips on the rounded peripheral areas in to the tangents these circumferential areas lie perpendicular planes. 2. Tool according to claim 1, characterized in that on most of the circular lines (1 to j57) each only two cutting diamond points (t) are arranged. 3. Tool according to claim 1 or 2, characterized in that that in the inner and outer cylindrical parts of the drill bit each axially extending cuttings discharge grooves (g) are formed with the - 21 - 2098A8 / 0553 2U5051 UL Cuttings discharge grooves in the cutting surface are in communication and that the spiral grooves at the bottom End each with the axially extending cuttings discharge grooves in the outer cylindrical part of the Drill bit connected. ■ 4. Tool according to one of claims 1 to 3, characterized in that the drilling tool has an outer diameter of 49.6 mm and an inner diameter of 35 mm, that furthermore the radius of the semicircular cutting surface is about 6.95 mm and the radius of the rounded peripheral areas 1.27 mm - 0.13 mm each, that furthermore the cutting diamond points (t) are arranged on 37 circular lines, the innermost and outermost circular lines each bearing four cutting diamond points and the remaining circular lines each carrying two cutting diamond points. - 22 - 209R48 / 0553 13, Blank page