US3703214A - Rock drilling bit - Google Patents

Rock drilling bit Download PDF

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Publication number
US3703214A
US3703214A US119783A US3703214DA US3703214A US 3703214 A US3703214 A US 3703214A US 119783 A US119783 A US 119783A US 3703214D A US3703214D A US 3703214DA US 3703214 A US3703214 A US 3703214A
Authority
US
United States
Prior art keywords
shaft
shank
portions
central axis
bit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US119783A
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English (en)
Inventor
Otto Boehm
Werner Scholz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
WERKZEUGBAU GmbH
Original Assignee
WERKZEUGBAU GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE19702014870 external-priority patent/DE2014870A1/de
Priority claimed from DE19702041985 external-priority patent/DE2041985B1/de
Application filed by WERKZEUGBAU GmbH filed Critical WERKZEUGBAU GmbH
Application granted granted Critical
Publication of US3703214A publication Critical patent/US3703214A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B10/00—Drill bits
    • E21B10/44—Bits with helical conveying portion, e.g. screw type bits; Augers with leading portion or with detachable parts
    • E21B10/445—Bits with helical conveying portion, e.g. screw type bits; Augers with leading portion or with detachable parts percussion type, e.g. for masonry
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/22—Rods or pipes with helical structure

Definitions

  • ROCK DRILLING BIT [72] Inventors: Otto Boehm, Starnberg; Werner Scholz, Soecking, both of Germany Assignee: horrbau GmbH,
  • asymmetrical portions are distributed along and around the central axis of the shaft in such a manner that a curve which interconnects the surface centers of gravity of these portions which are located off said central axis, forms a spiral helix.
  • These portions may be located in preferred sections of the drill bit shaft, especially in a transitionary section between the tip of the drill bit and the shaft proper or in another transitionary section between the shaft and a shank of the drilling bit.
  • the present invention relates to a rock drilling bit, especially one for use in connection with a torsional impact drilling machine. More particularly, the invention relates to drilling bits comprising a shaft with one or two feed screws for removing the borings.
  • any irregular laterally directed yielding movement of the drill bit is effective in an amplified manner in the transitional area or section between the tip of the drill bit and the shaft.
  • the conventional rock drill bit is produced by means of tools which are brought to bear upon a bit blank from two opposite sides. Stated differently, the tools are arranged or displaced about the circumference of the bit blank by 180 degrees.
  • the resulting drill bit has a cross section which in said transitional area or section increases from the bit shaft toward the tip of the bit with each winding of the feed screw, whereby the cross sectional areas of the resulting increasing diameters are respectively symmetrical relative to the longitudinal axis of the drill bit. Stated differently, all of the increasing diameter portions of the drill bit in said transitional area form a symmetric configuration relative to the longitudinal axis of the drill bit.
  • rock drill bit which has an increased rigidity or strength in its transitional sections or areas, especially between the shaft proper and the tip of the drill bit and/or between the shaft and a shank by means of which the drill bit is held in the chuck of the drilling machine;
  • a rock drilling bit in which the shaft or at least certain transitionary sections of the shaft have portions of increased dimensions relative to a central longitudinal axis of the shaft, whereby these portions are distributed around the shaft in such a manner that the surface centers of gravity of all cross sectional areas are located on a curve having substantially the shape of a spiral helix extending around the longitudinal central axis of the drill bit.
  • This teaching is applicable to drill bits having a double feed screw as well as to drill bits with a single feed screw for the borings.
  • the peripheral surface of the drill bit core which simultaneously forms the bottom of the feed screw has the shape of a spiral helix in the area of the strengthening, that is, in the transitionary area.
  • One possibility of producing the present drill bit with two feed screws is to machine the two screw windings by means of cutting tools both of which begin their respective cutting operation from the same generatrix and both of which are fed uniformly inwardly in the radial direction relative to the longitudinal axis of the drill bit shaft.
  • FIG. 1 illustrates a partial side view of a rock drilling bit according to the invention comprising two feed screws in the transitionary area showing the strengthened portion but omitting the remaining portions of the drill bit in order to save space;
  • FIG. 2 is an axial central section through the portion shown in FIG. 1;
  • FIG. 3 is a cross sectional view through the rock drill bit along line 3-3 of FIG. 1;
  • FIG. 4 is a cross sectional view through the the rock drill bit according to FIG. 1 but along line 44;
  • FIG. 5 illustrates a sectional view along line 5-5 in FIG. 1;
  • FIG. 6 is a view similar to that of FIG. 1 but showing a rock drill bit having a single feed screw and also illustrating the transitional area where the shaft of the drill bit is strengthened;
  • FIG. 7 is a sectional view along lines 7-7 in FIG. 6;
  • FIG. 8 is a sectional view along lines 88 in FIG. 6.
  • FIG. 1 the partial view of the drill bit 11 shows a portion of the shaft 1 the bit tip or shank of which is symbolized by the arrow 12 and the shank or tip of which is indicated by the arrow 13. Stated differently, it is irrelevant whether the dimensions to be described below increase from the shank to the tip or vice-versa.
  • the shank 13 is in practice adapted to be held in a chuck of a drilling machine not shown.
  • the shaft 1 of the drill bit is provided with two feed worms or threads a and b.
  • the dimensions and geometric shape of two adjacent screw windings are the same relative to each other.
  • the thread winding al of one screw has the same dimension and configuration as the thread winding b1 of the other screw. The same applies with regard to the thread windings a2 and b2.
  • the core 2 is provided with portions of enlarged diameter which are located in the transitionary area between the tip 12 and the core portion of uniform diameter.
  • the portions which have the largest cross sectional dimensions relative to the longitudinal axis 14 of the drill bit 11 are located immediately adjacent to the tip 12 of the drill bit as indicated by the thick windings a1 and bl.
  • the dimension of the core portions then gradually decreases in the direction toward the shank 13 as indicated by the windings a2 and b2. Further down toward the shank 13 the constant dimension of the core of the shaft is illustrated by the windings a and b. This is particularly illustrated in the sectional view of FIG. 3 where the core 2 has a circular cross section along its length of constant diameter.
  • FIG. 2 The teaching of the invention that adjacent portions of the shaft but belonging to two different screws shall have the same lateral dimension is clearly illustrated in FIG. 2, wherein it is seen that the radii of two adjacent portions are the same relative to the same generatrix 15 or 16 or 17 or 18, whereby said adjacent core portions are arranged one on top of the other.
  • the radial dimensions decrease in steps from the tip in the direction toward the shank 13.
  • the largest diameter R1 is shown adjacent to the tip 12
  • the next smaller diameter R2 is located intermediate the constant diameter R3 which is also shown in the sectional view of FIG. 3.
  • the stepwise decrease of the radial dimensions as shown in FIG. 2 results from the fact that the cutting tools are advanced radially during the formation of the screw windings by radial distances corresponding to R1 minus R2 or R2 minus R3 respectively during one full revolution or turn of the shaft blank.
  • FIG. 3 illustrates the cross sectional area through a portion of the shaft having a constant diameter, whereby the core 2 of the shaft has a constant circular cross section as indicated by the radius R3.
  • the section illustrated in FIG. 2 is located in an area wherein the shaft is provided with portions of increased dimensions.
  • Such portion 19 bulges, for example, to the left of the center axis 14 of FIG. 4, whereby an asymmetric configuration of the cross sectional area results.
  • the core 2 and the laterally bulging portion 19 have together a cross sectional configuration or shape corresponding approximately to that of an egg, whereby the center of gravity SP of this egg shape is located off center relative to the central axis 14.
  • the drill bit 21 of FIG. 6 comprises a single screw or worm 22 extending around a core 23 in the form of a helix
  • the diameter of the core is indicated at R6 and such diameter increases continuously, that is, without steps through the diameter R5 toward the diameter R4 where the core proper is provided with portions of increased radial dimensions as taught by the present invention.
  • the tip of the drill bit nor its shank are shown because the area comprising the portions of increased radial dimensions may be located in a transitional section between the tip and the shaft or between the shaft and the shank depending on the particular purpose for which the drill bit is intended.
  • the dimensions may increase from the tip to the shank or from the shank to the tip.
  • FIGS. 7 and 8 illustrate sectional views along respec- I tive lines in FIG. 6. It can be clearly seen in these figures that the cross section of the core 23 is asymmetrical in each place where there is a portion of increased radial dimension. Thus, the portion 24 in FIG. 7 bulges to the left and has a center of gravity SP2 which is off center relative to the central axis 25. The same applies to FIG. 8 however, here the portion 26 having the increased radial dimension bulges to the right of the central axis 25 so that the center of gravity SP3 is also located to the right and off the central axis 25.
  • a curve interconnecting the mentioned centers of gravity will form a spiral helix extending around the central axis 25.
  • the cross sectional configurations of the portions 25 and 26 also have the approximate outline of an egg.
  • the increased rigidity or strength of the present drill bit as compared to prior art rock drill bits may be explained substantially as follows, whereby comparable data or parameters are assumed as a basis for comparison.
  • the continuous surface which is controlling for the rigidity of the cross section of the drill bit shaft is larger than the comparable surface of the known drill bit because the cross sectional area in known drill bits is symmetrical relative to the longitudinal central axis so that merely the cross sectional area corresponding to the area of a respective circle can be taken into consideration for calculating the rigidity of the respective cross section.
  • the surface center of gravity which is a determining factor in ascertaining the rigidity of any given cross sectional area is displaced relative to the central axis of the drill bit.
  • the displacement of said surface centers of gravity resultsin an increased torsional rigidity because the outer torsional moment for a given cross section is equal to the sum of all static moments resulting from all outer or external forces relative to the tangent to the connecting line or curve of all surface centers of gravity in the respective center of gravity of the particular cross section. Accordingly, the point or rather line in which the torsional force is effective is not the central longitudinal axis of the drill bit but the connecting curve of all surface centers of gravity which curve has the shape of an approximate spiral helix extending around the longitudinal central axis of the drill bit.
  • a drill bit according to the invention which otherwise has the same geometrical conditions or features as a conventional drill bit, especially the same outer diameter, is more resistant or rather stronger than a conventional rock drill bit, against torsion and against bending as well as against a combination or superimposition of these load conditions.
  • the present teaching is applicable to drill bits having one or more feed screws for the borings.
  • the invention is based on the recognition that the stress considerations or problems which occur in the transitionary area between the shaft and the tip of drill bits having two feed screws, are also applicable in a quite similar manner in connection with drill bits having a shaft which is formed to comprise a single feed screw.
  • the practice has shown that generally the cross sections that are most likely to tear are those located in transitionary sections or areas between the shaft of the drill bit and the tip or between the shaft and the shank.
  • a rock drilling bit having a shaft with a longitudinal central axis therethrough, a bit tip at one end of said shaft, a shank at the opposite end of said shaft, and worm means extending around said shaft from said bit tip to said shank for removing borings, the improvement comprising shaft portions of different dimensions measured perpendicularly relative to said central axis, whereby said shaft portions have cross sectional areas of asymmetric shape relative to said central axis, each of said cross sectional areas having a surface center of gravity, said portions being distributed along said shaft and having such dimensions that a curve interconnecting said surface centers of gravity constitutes substantially a spiral helix extending around said central axis.
  • rock drilling bit comprising a central core, a section of uniform core diameter adjacent to said shank, and a transitionary section between said bit tip and said uniform diameter section, said shaft portions of different dimensions being located in said transitionary section in such a manner that the cross sectional area increases toward said bit tip and decreases from said bit tip toward said uniform diameter section.
  • rock drilling bit comprising a central core section of uniform core diameter adjacent to said bit tip, and a transitionary section between said shank and said uniform diameter section,
  • said shaft portions of different dimensions being located in said transitionary section in such a manner that the cross sectional area increases toward said shank and decreases from said shank toward said uniform diameter section.
  • each of said two screws has its own portions of different dimensions such that the radial dimension of a portion of one of said screws is equal to the radial dimension of an adjacent respective portion of the other screw relative to the same generatrix.
  • a rock drilling bit comprising a shaft having a longitudinal central axis, a bit tip at one end of the shaft, a shank at the opposite end of the shaft, first and second worms extending around said shaft between said bit tip and said shank for removing borings, a transitional section forming part of the shaft adjacent to said bit tip, and shaft portions of different cross sectional dimensions located in said transitional area so that the cross sectional areas of the shaft increase toward said bit tip and decrease toward said shank, said different cross sectional dimensions having an asymmetrical shape relative to said central axis and surface centers of gravity so that a curve connecting said surface centers of gravity constitutes substantially a spiral helix extending around said central axis.
  • a rock drilling bit comprising a shaft having a longitudinal central axis, a bit tip at one end of the shaft, a shank at the opposite end of the shaft, a single worm extending around said shaft between said bit tip and said shank for removing borings, a transitional section forming part of the shaft adjacent to said shank, and shaft portions of difierent cross sectional dimensions located in said transitional area so that the cross sectional areas of the shaft increase toward said shank and decrease toward said bit tip, said different cross sectional dimensions having an asymmetrical shape relative to said central axis and surface centers of gravity so that a curve connecting said surface centers of gravity constitutes substantially a spiral helix extending around said central axis.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Earth Drilling (AREA)
US119783A 1970-03-26 1971-03-01 Rock drilling bit Expired - Lifetime US3703214A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19702014870 DE2014870A1 (enrdf_load_stackoverflow) 1970-03-26 1970-03-26
DE19702041985 DE2041985B1 (de) 1970-08-25 1970-08-25 Gesteinsbohrer

Publications (1)

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US3703214A true US3703214A (en) 1972-11-21

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US119783A Expired - Lifetime US3703214A (en) 1970-03-26 1971-03-01 Rock drilling bit

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US (1) US3703214A (enrdf_load_stackoverflow)
CH (1) CH517244A (enrdf_load_stackoverflow)
DK (1) DK124183B (enrdf_load_stackoverflow)
FR (1) FR2083938A5 (enrdf_load_stackoverflow)
NL (1) NL7102712A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0009838A1 (fr) * 1978-09-28 1980-04-16 Ph. GUEX & FILS S.A. Foret à pierre pour perceuse-frappeuse ou marteau électrique
US5002139A (en) * 1988-07-16 1991-03-26 Hawera Probst Gmbh & Co. Drilling tool
WO1998042944A1 (en) * 1997-03-24 1998-10-01 Sibille, Patrick, Neil Apparatus and a method for drilling boreholes
US6082472A (en) * 1997-01-22 2000-07-04 Fundex N.V. Earth displacement drill

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3014693A1 (de) * 1980-04-16 1981-10-22 Hilti AG, 9494 Schaan Gesteinsbohrer
DE3434633A1 (de) * 1984-09-21 1986-04-03 Eichner, Wolf D., Dr.jur., 8630 Coburg Aufnahmekamera

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1107927A (en) * 1914-01-06 1914-08-18 Heinrich Fuchs Ground-auger.
FR22192E (fr) * 1915-04-06 1921-05-14 Frederic Guillierme Machine pour le creusage des trous de mine
US2572839A (en) * 1947-10-23 1951-10-30 Mcclinton John Combination key seat remover and vibration distributor for well drilling
US3605921A (en) * 1968-09-11 1971-09-20 Mayer Kg Fa Drill for producing holes for plants in flower pots or other containers

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1107927A (en) * 1914-01-06 1914-08-18 Heinrich Fuchs Ground-auger.
FR22192E (fr) * 1915-04-06 1921-05-14 Frederic Guillierme Machine pour le creusage des trous de mine
US2572839A (en) * 1947-10-23 1951-10-30 Mcclinton John Combination key seat remover and vibration distributor for well drilling
US3605921A (en) * 1968-09-11 1971-09-20 Mayer Kg Fa Drill for producing holes for plants in flower pots or other containers

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0009838A1 (fr) * 1978-09-28 1980-04-16 Ph. GUEX & FILS S.A. Foret à pierre pour perceuse-frappeuse ou marteau électrique
FR2437921A1 (fr) * 1978-09-28 1980-04-30 Guex & Fils Sa Ph Foret a pierre pour perceuse-frappeuse ou marteau electrique
US5002139A (en) * 1988-07-16 1991-03-26 Hawera Probst Gmbh & Co. Drilling tool
US6082472A (en) * 1997-01-22 2000-07-04 Fundex N.V. Earth displacement drill
WO1998042944A1 (en) * 1997-03-24 1998-10-01 Sibille, Patrick, Neil Apparatus and a method for drilling boreholes

Also Published As

Publication number Publication date
DK124183B (da) 1972-09-25
NL7102712A (enrdf_load_stackoverflow) 1971-09-28
CH517244A (de) 1971-12-31
FR2083938A5 (enrdf_load_stackoverflow) 1971-12-17

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