EP4155031A1 - Brechwerkzeug, brechhammer und verfahren zur aufrechterhaltung der form eines brechwerkzeugs - Google Patents

Brechwerkzeug, brechhammer und verfahren zur aufrechterhaltung der form eines brechwerkzeugs Download PDF

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Publication number
EP4155031A1
EP4155031A1 EP21198516.3A EP21198516A EP4155031A1 EP 4155031 A1 EP4155031 A1 EP 4155031A1 EP 21198516 A EP21198516 A EP 21198516A EP 4155031 A1 EP4155031 A1 EP 4155031A1
Authority
EP
European Patent Office
Prior art keywords
tool
breaking
hardness
zone
zones
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.)
Withdrawn
Application number
EP21198516.3A
Other languages
English (en)
French (fr)
Inventor
Ossi Niemioja
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.)
Sandvik Mining and Construction Oy
Original Assignee
Sandvik Mining and Construction Oy
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
Application filed by Sandvik Mining and Construction Oy filed Critical Sandvik Mining and Construction Oy
Priority to EP21198516.3A priority Critical patent/EP4155031A1/de
Publication of EP4155031A1 publication Critical patent/EP4155031A1/de
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D17/00—Details of, or accessories for, portable power-driven percussive tools
    • B25D17/02—Percussive tool bits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D2222/00—Materials of the tool or the workpiece
    • B25D2222/21—Metals
    • B25D2222/42—Steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25D—PERCUSSIVE TOOLS
    • B25D2250/00—General details of portable percussive tools; Components used in portable percussive tools
    • B25D2250/211—Cross-sections of the tool

Definitions

  • the invention relates to a breaking tool of a breaking hammer.
  • the invention further relates to a breaking hammer and to a method for maintaining shape of breaking tool.
  • Breaking hammers are used to break hard materials, such as rock, concrete, and the like.
  • the breaking hammer comprises a percussion device for generating impact pulses to a breaking tool connectable to the breaking hammer.
  • breaking hammers are used in demanding conditions and in different applications wherefore breaking tools of the breaking hammers are subjected to high stresses and other damaging phenomena.
  • breaking tools There are different tool designs of breaking tools for different use.
  • the breaking tools may be provided with a functionally shaped tip portion.
  • the tip of the tool wears and the original shape of the tool is lost. Therefore, there is a need to reshape the tip portion of the breaking tool several times during its service life. Since the tool is made of hardened steel material, machining of the tool is difficult and time consuming.
  • An object of the invention is to provide a novel and improved breaking tool and breaking hammer, and further to provide a novel and improved method of keeping a desired shape of a breaking tool during use.
  • the breaking tool according to the invention is characterized by the characterizing features of the first independent apparatus claim.
  • the breaking hammer according to the invention is characterized by the characterizing features of the second independent apparatus claim.
  • the method according to the invention is characterized by the characterized features of the independent method claim.
  • a basic structure of a breaking tool comprises an elongated shaft, an impact end at a first end of the shaft for receiving impact pulses, and a functional portion extending a first distance from a second end towards the first end.
  • the tool is made of one steel material and is quenched and tempered for providing increased hardness.
  • the shaft comprises a wearing portion extending a second distance from the functional portion towards the first end.
  • An outer surface of cross section of the wearing portion of the tool comprises at least two zones having different hardness.
  • tool has a desired tool design at the wearing portion, and the outer surface of the wearing portion has deviating hardness distribution on the outer surface of the cross section.
  • An advantage of the disclosed solution is that the tool can maintain its original shape at a tip part of the tool due to the zones with the different hardness.
  • the hardness distribution is selected in accordance with the designed cross sectional shape of the tool. Harder zones are placed at areas which need to remain longer in use, and softer zones are placed at areas which are allowed to wear quicker. It has been noted that hardness of the material correlates well to capability to resist wearing, especially when rock breaking tools are considered. Then the tool may have a self-dressing or self-shaping feature wherefore there is no need to process the tool with any separate apparatuses and no separate service breaks are needed.
  • the purpose of the disclosed solution is to avoid the shaped tool to become a conventional blunt tool due to the wearing during the use. This way the functionally shaped tool can serve in the intended usage for its entire useful life.
  • the cross section of the functional portion is provided with an outer surface having a shape which is non-rotationally symmetrical.
  • the cross section of the wearing portion is round.
  • the cross section of the wearing portion comprises varying hardness profile inside the second distance.
  • the cross section of the wearing portion comprises a core part surrounded by a surface part.
  • the surface part comprises at least two zones with different hardness, whereby there is at least one harder zone and at least one softer zone.
  • the core part is provided with hardness greater than hardness of the softer zone on the surface part.
  • the cross section of the wearing portion comprises one or more harder surface zones and the harder core part, as well as one or more softer surface zones. Then the wearing portion can wear at the softer zones and resist the wearing at the core part and the designed harder zones, whereby the designed shape of the tool can be maintained.
  • the tool is of flat chisel type.
  • the cross section of the wearing portion comprises one harder zone extending transversally from edge to edge of the outer surface, and two softer zones on opposing sides of the harder zone.
  • the softer zones are positioned perpendicularly relative to the harder zone.
  • the tool is of pyramid type.
  • the cross section of the wearing portion comprises four harder zones and four softer zones.
  • the softer zones are positioned perpendicularly relative to each other.
  • the harder zones form edge-like zones on the surface whereas the softer zones form wearable segments between the edge-like zones.
  • the wearing portion comprises at least one groove-like softer material zone in longitudinal direction of the tool.
  • the groove mentioned in the previous embodiment is a dust removal groove or flushing groove.
  • the tool has a primary hardness generated by quenching and tempering and extending through the entire cross section of the tool. Then the cross section of the wearing portion comprises at least one annealed zone wherein hardness of the material is reduced when compared to the mentioned primary hardness.
  • the primary hardness is generated by means of a heating and cooling process for the entire tool and thereafter a heat treatment is subjected to selected limited surface areas of the tool to soften the material from the primary hardness.
  • the annealing prepares the selected surface areas for the wearing process.
  • the difference in hardness values of the at least one harder zone and the hardness of the at least one softer zone is at least 7 HRC.
  • the difference in hardness values is generated intentionally and is not based on any inaccuracies in the manufacturing process and the base material.
  • the difference in hardness values of the at least one harder zone and the hardness of the at least one softer zone is at least 10 HRC.
  • the core part and the selected harder area on the surface have hardness values of at least 48 HRC; and the at least softer area has hardness value of maximum 40 HRC.
  • the solution relates to a rock breaking hammer comprising: an elongated body; an impact device arranged inside the body and configured to generate impact pulses; and a breaking tool.
  • the breaking tool is in accordance with the features and embodiments disclosed in this document.
  • the solution relates to a method of maintaining shape of a breaking tool of a breaking hammer during its service life.
  • the method comprises: forming the tool of one steel material and heat treating the tool to have designed hardness; and providing the tool with a functional end part at an end part opposite to an impact end.
  • the method further comprises: providing the tool with a wearing portion extending an axial distance from the functional end part towards the impact end; and providing the outer surface of the tool with at least one harder zone and at least one softer zone at a cross section of the wearing portion of the tool.
  • the disclosed method comprises reducing hardness of material of at least one zone on the surface of the wearing portion by means of induction heating.
  • An advantage of the induction heating is that it is a fast and efficient contactless method for heating conductive steel materials by applying a fluctuating magnetic field. Induction heating provides improved control for the annealing process. Repeatable heating profiles can easily be obtained by precise regulation of the heating power. Since the workpiece is directly heated by the magnetic field, a faster response can be achieved. Moreover, the induction annealing may be accomplished without a controlled atmosphere.
  • the induction heating device comprises induction coils and number of these induction coils directed to a cross section of the wearing portion defines number of softer zones being created. Ranges of the coils effect on the shape of the harder zone of the wearing portion. The process may be called as an induction zone annealing.
  • laser technology or other zone annealing techniques processes and apparatuses may be implemented for creating the wearable annealed softer zones on the tool.
  • annealing thickness i.e., thickness of the softer zone can be adjusted for producing desired hardness profiles.
  • the wearing portion may have different annealing thickness when examined in longitudinal direction of the tool, for example.
  • the disclosed method comprises providing the functional end part with a cross-sectional shape having an outer surface shape which deviates from a circular shape.
  • Figure 1 shows a breaking hammer 1 arranged on a free end of a boom 2 in a working machine 3, such as an excavator.
  • the boom 2 may be arranged on any movable carriage or on a fixed platform of a crushing apparatus.
  • the breaking hammer 1 comprises an impact device 4 for generating impact pulses.
  • the breaking hammer 1 may be pressed by means of the boom 2 against material 5 to be broken and impacts may be simultaneously generated with the impact device 4 to a breaking tool 6 connected to the breaking hammer 1.
  • the tool 6 transmits the impact pulses to the material 5 to be broken.
  • the impact device 4 may be hydraulic, whereby it may be connected to the hydraulic system of the working machine 2.
  • Figure 2 discloses a hydraulic impact device 4 which is configured to generate impact pulses by means of a percussion element, such as percussion piston 7, that may be moved back and forth in the impact direction and return direction under the influence of hydraulic fluid.
  • the percussion piston 7 is configured to strike an impact surface or impact end 8 which is located at a first end of a breaking tool 6.
  • the breaking tool 6 may be connected to a body 9 of the impact device 4 by means of transverse locking pins 10, for example.
  • the breaking tool 6 protrudes partly out of the body 9 and thus comprises a protruding portion Pp at its second end portion.
  • the protruding portion Pp is divided into a functional portion Fp at a tip part of the breaking tool 6, and into a wearing portion Wp extending from the functional portion Fp towards a first end of the breaking tool 6.
  • the functional portion Fp and the wearing portion Wp are as it is disclosed in this document.
  • Figures 3 - 5 disclose three breaking tools 6 with different designs at their functional portions Fp and wearing portions Wp. On left side of each Figure 3 - 5 the tool is seen in axial direction and on right side the same tool is seen from side.
  • the functional portion Fp extends a first distance L1 from a second end towards the first end, and the wearing portion Wp extends a second distance L2 from the functional portion Fp towards the first end.
  • Figure 3 discloses a flat chisel type breaking tool 6 comprising a flat middle portion 11 on its functional portion Fp.
  • the cross section of the wearing portion Wp comprises one harder zone extending transversally from edge to edge of the outer surface, and two softer zones on opposing sides of the harder zone, as it is shown in Figures 6 , 7 and 8 .
  • an outer surface of cross section of the wearing portion Wp of the tool 6 comprises at least two zones having different hardness.
  • Figure 4 discloses a pyramid type breaking tool 6 comprising four sloped surfaces 12 on the functional portion Fp. Then, the cross section of the wearing portion Wp comprises four harder zones and four softer zones. The softer zones are positioned perpendicularly relative to each other, as it is shown in Figures 9 and 10 .
  • Figure 5 discloses a breaking tool 6 comprising an axial groove 13 on its functional portion Fp.
  • the functional portion Fp may comprise a conical tip 14.
  • the wearing portion Wp comprises at least one groove-like softer material zone 13a in longitudinal direction of the tool 6.
  • the groove feature remains despite of the wearing because of the softer material zone 13a. This way the groove may be utilized for example for dust removing and flushing purposes for the entire service life of the tool 6.
  • Figure 6 discloses a cross-sectional view of a chisel-type breaking tool 6 at its wearing portion Wp.
  • the wearing portion Wp is treated with an annealing process there are two opposing annealed softer zones Sz1 with reduced hardness when compared to intermediate zones Iz between them.
  • the mentioned softer zones Sz1 are designed to wear out and to thereby expose a new middle portion 11a for the flat chisel-type tool.
  • the intermediate zones Iz typically comprises several zone layers with slightly different hardness since the annealing temperature effects differently at different distances from the outer surface of the tool.
  • Figure 7 discloses a principle of induction zone annealing by means of two opposing induction coils 15 directed transversally towards an outer surface S of the tool 6 so that the coils 15 can threat two opposing zones 16 in a cross-section of the tool 6. Between the treated zones 16 there remains an untreated zone 17.
  • Figure 8 discloses a result of the treatment shown in Figure 7 .
  • the cross-section comprises two softer zones Sz1 and a harder zone Hz between them.
  • Figure 9 discloses induction zone annealing executed by means of four induction coils 15. Then the coils 15 can treat four zones 16 and at central part there is an untreated zone 17.
  • Figure 10 discloses a result of the treatment shown in Figure 9 .
  • the cross-section comprises four softer zones Sz2 and a harder zone Hz surrounded by them.
  • the harder zone Hz may comprise a hard core Hc and four hard edge zones Hez.
  • Figure 11 discloses a graph of measuring results of hardness in function of distance from an outer surface of a wearing portion. As can be seen the hardness values increase at desired zones towards an inner structure of the tool because the annealing is designed to reach only desired deepness of the material so that the core can remain at designed hardness.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Heat Treatment Of Articles (AREA)
EP21198516.3A 2021-09-23 2021-09-23 Brechwerkzeug, brechhammer und verfahren zur aufrechterhaltung der form eines brechwerkzeugs Withdrawn EP4155031A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP21198516.3A EP4155031A1 (de) 2021-09-23 2021-09-23 Brechwerkzeug, brechhammer und verfahren zur aufrechterhaltung der form eines brechwerkzeugs

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP21198516.3A EP4155031A1 (de) 2021-09-23 2021-09-23 Brechwerkzeug, brechhammer und verfahren zur aufrechterhaltung der form eines brechwerkzeugs

Publications (1)

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EP4155031A1 true EP4155031A1 (de) 2023-03-29

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EP21198516.3A Withdrawn EP4155031A1 (de) 2021-09-23 2021-09-23 Brechwerkzeug, brechhammer und verfahren zur aufrechterhaltung der form eines brechwerkzeugs

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE592580C (de) * 1934-02-10 Walter Huelsbruch Dr Ing Spitzeisen oder Meissel, vornehmlich fuer den Bergbau
AT377207B (de) * 1981-05-22 1985-02-25 Schobesberger Ernst Ing Verfahren zur herstellung von schaftmeisseln
DE19757271A1 (de) * 1997-12-22 1999-06-24 Hilti Ag Werkzeug
WO2005014238A1 (de) * 2003-08-07 2005-02-17 Stahlwerke Bochum Gmbh Komposit-werkzeug für schlagende und/oder abrasive belastungen

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE592580C (de) * 1934-02-10 Walter Huelsbruch Dr Ing Spitzeisen oder Meissel, vornehmlich fuer den Bergbau
AT377207B (de) * 1981-05-22 1985-02-25 Schobesberger Ernst Ing Verfahren zur herstellung von schaftmeisseln
DE19757271A1 (de) * 1997-12-22 1999-06-24 Hilti Ag Werkzeug
WO2005014238A1 (de) * 2003-08-07 2005-02-17 Stahlwerke Bochum Gmbh Komposit-werkzeug für schlagende und/oder abrasive belastungen

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