EP4275856A1 - Burin à longue durée de vie et procédé de fabrication d'un tel burin - Google Patents

Burin à longue durée de vie et procédé de fabrication d'un tel burin Download PDF

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Publication number
EP4275856A1
EP4275856A1 EP22172528.6A EP22172528A EP4275856A1 EP 4275856 A1 EP4275856 A1 EP 4275856A1 EP 22172528 A EP22172528 A EP 22172528A EP 4275856 A1 EP4275856 A1 EP 4275856A1
Authority
EP
European Patent Office
Prior art keywords
section
chisel
area
hardness
core
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.)
Pending
Application number
EP22172528.6A
Other languages
German (de)
English (en)
Inventor
Árpád Horváth
Bertalan Kecskés
Gabor Rakonczai
Norbert Tajthi
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.)
Hilti AG
Original Assignee
Hilti AG
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 Hilti AG filed Critical Hilti AG
Priority to EP22172528.6A priority Critical patent/EP4275856A1/fr
Priority to PCT/EP2023/061090 priority patent/WO2023217542A1/fr
Publication of EP4275856A1 publication Critical patent/EP4275856A1/fr
Pending 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
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28D—WORKING STONE OR STONE-LIKE MATERIALS
    • B28D1/00—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor
    • B28D1/26—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor by impact tools, e.g. by chisels or other tools having a cutting edge
    • 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

Definitions

  • the invention is based on a chisel which has a working section, a shaft section and a striking surface and a longitudinal axis running through the working section, the shaft section and the striking surface.
  • Such chisels are used on construction sites for the chiseling of mineral rock, such as concrete.
  • the working section wears out, so that the cumulative use from a first use to a last possible use after the working section has been worn to the maximum results in a theoretically maximum possible service life, i.e. the maximum theoretical service life.
  • the object of the present invention is therefore to offer generic chisels with a low risk of breakage.
  • a process for producing such chisels is also desirable.
  • a chisel which has a working section, a shaft section, a striking surface and a longitudinal axis running through the working section, the shaft section and the striking surface.
  • a first structural core region In a cross section of the working section running transversely to the longitudinal axis, a first structural core region has a first core hardness that is significantly lower than a first external hardness in a first external area outside the first structural core region of the same cross section.
  • the chisel can therefore have material of different hardnesses in the area of the working section.
  • the chisel can be softer inside in the area of the working section than on its surface.
  • the interior particularly in the first structural core area, can have a higher toughness than on the surface and/or in the first outer area.
  • a “significant” difference between two values of a measurement variable can be understood to mean a difference of at least 10%, in particular of at least 20%.
  • an insignificant difference between the two values can be understood to mean a deviation of, for example, less than 10 percent, in particular less than 5%.
  • a longitudinal plane of the chisel can also be viewed as the longitudinal axis, for example in the case of a non-rotationally symmetrical chisel such as a channel chisel.
  • the working section can have webs, projections and/or the like. These can be set up to reduce the risk of getting stuck in a surface that is being processed.
  • Hardness specifications can be determined in particular using the Vickers method. Alternatively or additionally, hardness information can also be determined according to Rockwell, for example according to scale C.
  • a second structural core region may have a second core hardness.
  • the second core hardness can be significantly lower than a second external hardness in a second external area outside the second core region of the same cross section.
  • the shaft section can therefore have a core that is soft in relation to its surface.
  • the first core hardness can be significantly greater than the second core hardness, so that the first core hardness can be significantly greater than the second core hardness, so that the first core hardness
  • Working section is harder overall than the shaft section.
  • the working section and thus the chisel can therefore continue to have a long, theoretically maximum possible service life.
  • the first core hardness can be significantly lower than the second external hardness.
  • the first structural core region can have temper martensite, in particular consist of temper martensite.
  • the tempering martensite-containing microstructure can be produced by at least double heat treatment, in particular using, among other things, at least one shock induction heat treatment.
  • the first outer area can have martensite, in particular consist of martensite.
  • the microstructure can be produced by at least one induction heat treatment.
  • the cross section of the bit comprising the first outer area and the first structural core region may have a geometric core region which is defined by the largest area ellipse inscribed in the cross section.
  • Particularly break-resistant chisels can then have an area ratio of the first structural core area to the geometric core area in the range of 40 to 80%.
  • the scope of the invention also includes a method for producing a chisel with the features described above and/or below, wherein a chisel blank which has a working section, a shaft section and a striking surface and a longitudinal axis running through the working section, the shaft section and the striking surface has, is processed.
  • the chisel blank cannot yet be heat treated.
  • the method includes an induction heat treatment of the working portion, wherein both the first outer area and the first core region are hardened, and an induction heat shock treatment of the work portion such that the first outer area has a significantly greater hardness than the first core region.
  • the induction heat treatment is carried out first and then the induction heat shock treatment.
  • the induction heat shock treatment can extend over the entire bit, in particular over the working section and the shank section.
  • Fig. 1 shows a chisel 10.
  • the chisel 10 is designed as a pointed chisel. Has a working section 12 , a shaft section 14 and a striking surface 16 .
  • the chisel 10 has a tip 18 at the free end of its working section 12.
  • a longitudinal axis L runs through the working section 12, the shaft section 14 and the striking surface 16.
  • the chisel 10 can be struck by striking its striking surface 16, for example using a machine tool mounted in the area of the striking surface 16 (in Fig. 1 not shown), are driven into a subsoil 20 .
  • the subsurface 20 is as shown in the example Fig. 1 a mineral substrate, for example reinforced concrete.
  • the working section 12 has a plurality of ribs 22 .
  • the ribs 22 can be designed to prevent the chisel from getting stuck in the subsurface 20 or at least to reduce the risk of such getting stuck.
  • the working section 12 Over the service life of the chisel 10, the working section 12 usually wears out, but the shaft section 14 does not wear out, or at most only to an insignificant extent.
  • the chisel 10 reaches its maximum end of use when the working section 12 is shortened completely or at least to a certain minimum, unless the chisel 10 is broken or similarly seriously damaged beforehand.
  • An insertion end 24 is formed on the shaft section 14.
  • the insertion end 24 can be designed as a hexagon and/or comprises such a hexagon.
  • the insertion end 24 corresponds to a different standard, for example a standard usually referred to as "SDS-Plus” or "SDS-Max”.
  • Fig. 2 shows a hardness diagram for local hardness of the chisel 10 along its longitudinal axis L.
  • the abscissa corresponds to the respective position along the longitudinal axis L.
  • FIG. 2 A course of hardness in outer areas as well as in core areas is shown in accordance with the respective position x or the respective cross section at position x along the longitudinal axis L.
  • Fig. 3 shows a schematic longitudinal sectional view of the chisel 10 along the longitudinal axis L, so that it can be seen which sections the hardness applies to Fig. 2 refer to each.
  • a first structural core region KB1 a first structural core region KB1 , a first first external region AB1, which runs radially around the first structural core region KB1 , and a second structural core region KB2 with a second external region AB2 which runs radially around this are shown.
  • the chisel 10 has a first core hardness HK1 as hardness in the area of its working section 12 in the first structural core area KB1.
  • the first core hardness HK1 is significantly lower than a hardness in the first external area AB1, hereinafter referred to as the first external hardness HA1 , outside the first structural core area KB1 within the same cross section of the working section 12.
  • the first core hardness HK1 is between 50 and 80 percent, for example between 60 and 70 percent, the first external hardness HA1.
  • the first core hardness HK1 can be in the range of 400 and 450 HV.
  • the first external hardness HA1 can be in the range of 600 to 650 HV.
  • a second structural core region KB2 which is formed along the shaft section 14, has a hardness, hereinafter referred to as second core hardness HK2 , at least in a cross section. This is significantly lower than a second external hardness HA2 in a second external area AB2 outside the second structural core region KB2 of the same cross section of the shaft section 14.
  • the core hardness HK1 is significantly greater than the second core hardness HK2.
  • the hardnesses along the longitudinal axis L can be constant or at least essentially constant.
  • the first external hardness HA1 and the second external hardness HA2 can be the same or at least substantially the same.
  • Fig. 2 also shows that the first core hardness HK1 is significantly lower than the first external hardness HA1. It is also significantly lower than the second external hardness HA2, particularly when the first and second external hardness HA1 and HA2 are the same or at least essentially the same.
  • the first outside area AB1 is made of martensite. It can be completely hardened.
  • the first structural core region KB1 is made of temper martensite.
  • the tip 18 can also be made of martensite. However, it is also conceivable, in particular after a certain amount of wear on the chisel 10 and in particular on the tip 18, when the first structural core region KB1 extends into the tip 18, that the tip 18 alternatively or additionally has temper martensite.
  • microstructures in particular pearlite and/or ferrite, may be present in the interior of the shaft section 14, in particular in the second structural core region KB2.
  • Fig. 4a and Fig. 4b show exemplary cross-sections of various chisels 10.
  • the cross-sections come from respective work sections 12 (see Fig. 1 ).
  • Fig. 4a shows cross sections of pointed chisels, whereas Fig. 4b Showing cross sections of flat chisels.
  • the respective first core areas KB1 are marked as well as associated geometric core areas KG .
  • the geometric core areas KG are defined as ellipses with the largest area inscribed in the respective cross section of the working section 12.
  • the area ratios of the first structural core areas KB1 to the geometric core areas KG associated with them are in the range from 30 to 90 percent, in particular in the range from 40 to 80 percent.
  • the ratio of the diameter dKB1 of the first structural core region KB1, which is circular in cross section, to the diameter dAB1 of the associated outer region AB1 for the first pointed chisel from the left is in Fig. 4a approx. 63%, resulting in an area ratio of 0.4, corresponding to 4 * 10 1 percent.
  • Fig. 5 shows a flowchart of a method 1000 for producing a chisel 10.
  • a chisel blank is first produced which has a working section 12, a shaft section 14 and a striking surface 16.
  • the chisel blank to be produced has an elongated shape, so that a longitudinal axis L runs through its working section 12, the shaft section 14 and the striking surface 16.
  • the working section 12 is heat treated using induction heat.
  • both the first external area AB1 and the first structural core area KB1 reach a homogeneous austenitization temperature.
  • the full cross section of the working section 12 is hardened.
  • Both the first outer area AB1 and the first structural core area KB1 are converted into martensite and hardened accordingly.
  • the working section 12 is now shock heat treated using an induction heat shock treatment.
  • This further hardens the first outside area AB1.
  • This gives the first outer area AB1 a significantly greater hardness than the first structural core area KB1.
  • the shock heat treatment results in a lower temperature increase than in the first external area AB1.
  • reaching an austenitization temperature can be avoided, so that at least essentially no further allotropic conversion takes place.
  • a phase comprising ⁇ + Fe 3 C can form in the first structural core region KB1.
  • the shaft portion 14 may be heat treated prior to the shock heat treatment.
  • the applicant has carried out comparative studies on the service life of chisels 10, in particular manufactured according to method 1000, in comparison to already known comparison chisels.
  • chisels are to be tested for up to six hours in heavily reinforced reinforced concrete, in particular with three-layer steel reinforcements with a diameter of 16 mm and pitches of 150 x 150, using a commercially available chisel hammer with an impact energy in the range of 25 to 30 J per impact mm, and concrete of class C25/30 GK32, has been tested.
  • the risk of breakage of the tested chisels 10 is therefore significantly reduced compared to the tested comparison chisels.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • Heat Treatment Of Articles (AREA)
EP22172528.6A 2022-05-10 2022-05-10 Burin à longue durée de vie et procédé de fabrication d'un tel burin Pending EP4275856A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP22172528.6A EP4275856A1 (fr) 2022-05-10 2022-05-10 Burin à longue durée de vie et procédé de fabrication d'un tel burin
PCT/EP2023/061090 WO2023217542A1 (fr) 2022-05-10 2023-04-27 Ciseau présentant une longue durée de vie, et procédé de production d'un tel ciseau

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP22172528.6A EP4275856A1 (fr) 2022-05-10 2022-05-10 Burin à longue durée de vie et procédé de fabrication d'un tel burin

Publications (1)

Publication Number Publication Date
EP4275856A1 true EP4275856A1 (fr) 2023-11-15

Family

ID=81603715

Family Applications (1)

Application Number Title Priority Date Filing Date
EP22172528.6A Pending EP4275856A1 (fr) 2022-05-10 2022-05-10 Burin à longue durée de vie et procédé de fabrication d'un tel burin

Country Status (2)

Country Link
EP (1) EP4275856A1 (fr)
WO (1) WO2023217542A1 (fr)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0925881A1 (fr) * 1997-12-22 1999-06-30 HILTI Aktiengesellschaft Outil
US20040047757A1 (en) * 2002-05-10 2004-03-11 Komatsu Ltd. High-hardness, high-toughness steels and crawler components, earth wear resistant components, fastening bolts, high-toughness gears, high-toughness, high contact pressure resistance gears, and wear resistant steel plates using the same
US20110174550A1 (en) * 2008-10-07 2011-07-21 Varel International, Ind., L.P. Process for manufacturing a part comprising a block of dense material constituted of hard particles and of binder phase having a gradient of properties, and resulting part
US20180087137A1 (en) * 2015-04-21 2018-03-29 Komatsu Ltd. Chisel and steel for chisel
US20190111488A1 (en) * 2016-05-17 2019-04-18 Komatsu Ltd. Wear-resistant component and method for producing the same
US20210252686A1 (en) * 2020-02-19 2021-08-19 Robert Bosch Gmbh Insert Tool and Method for Producing an Insert Tool

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0925881A1 (fr) * 1997-12-22 1999-06-30 HILTI Aktiengesellschaft Outil
US20040047757A1 (en) * 2002-05-10 2004-03-11 Komatsu Ltd. High-hardness, high-toughness steels and crawler components, earth wear resistant components, fastening bolts, high-toughness gears, high-toughness, high contact pressure resistance gears, and wear resistant steel plates using the same
US20110174550A1 (en) * 2008-10-07 2011-07-21 Varel International, Ind., L.P. Process for manufacturing a part comprising a block of dense material constituted of hard particles and of binder phase having a gradient of properties, and resulting part
US20180087137A1 (en) * 2015-04-21 2018-03-29 Komatsu Ltd. Chisel and steel for chisel
US20190111488A1 (en) * 2016-05-17 2019-04-18 Komatsu Ltd. Wear-resistant component and method for producing the same
US20210252686A1 (en) * 2020-02-19 2021-08-19 Robert Bosch Gmbh Insert Tool and Method for Producing an Insert Tool

Also Published As

Publication number Publication date
WO2023217542A1 (fr) 2023-11-16

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