EP0079864B1 - Procédé de traitement de douille pour patin de chenille des tracteurs ou véhicules chenillés par carburation à température élevée dans une atmosphère carburée produite in situ, par trempe directe, revenu des bouts et recuit de détente - Google Patents

Procédé de traitement de douille pour patin de chenille des tracteurs ou véhicules chenillés par carburation à température élevée dans une atmosphère carburée produite in situ, par trempe directe, revenu des bouts et recuit de détente Download PDF

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Publication number
EP0079864B1
EP0079864B1 EP82830210A EP82830210A EP0079864B1 EP 0079864 B1 EP0079864 B1 EP 0079864B1 EP 82830210 A EP82830210 A EP 82830210A EP 82830210 A EP82830210 A EP 82830210A EP 0079864 B1 EP0079864 B1 EP 0079864B1
Authority
EP
European Patent Office
Prior art keywords
bushes
carburizing
temperature
furnace
chamber
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
Application number
EP82830210A
Other languages
German (de)
English (en)
Other versions
EP0079864A1 (fr
Inventor
Walter Grilli
Franco De Meo
Ivan Franchini
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.)
Italtractor ITM SpA
Original Assignee
Italtractor ITM SpA
ITALTRACTOR MECCANICA ITM SpA
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 Italtractor ITM SpA, ITALTRACTOR MECCANICA ITM SpA filed Critical Italtractor ITM SpA
Publication of EP0079864A1 publication Critical patent/EP0079864A1/fr
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Publication of EP0079864B1 publication Critical patent/EP0079864B1/fr
Expired legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/80—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/78—Combined heat-treatments not provided for above
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
    • C21D9/14—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes wear-resistant or pressure-resistant pipes

Definitions

  • the invention refers to the production of bushes for the tracks of tracked vehicles in general, such as tractors and earthmoving machinery, more precisely, the invention refers to a production process in which the bushes are carburized at high temperature in a carburizing atmosphere produced in situ (using techniques which are already known as such but which have never been applied simultaneously to the items in question), and then are individually quenched and finally undergo a tempering of the ends and a total stress relief.
  • the bush rotatably coupled to a pin, forms the articulated junction element between the track links.
  • the technological properties the bush must have in order to withstand such use conditions include high surface hardness combined with good tensile strength, good fatigue strength and good impact strength. These properties are ensured by specifications that call for a completely martensitic structure in the centre and on the surface, 5-8 ASTM austenitic grain, surface hardness in excess of 55 HRC, centre hardness of 32-44 HRC and surface hardnes at the ends of 35-46 HRC.
  • Attainment of the desired mechanical properties is an essential condition for the production of parts, such as bushes, subject to wear and decidedly unusual stresses, when in use.
  • parts such as bushes
  • parts such as bushes
  • wear and decidedly unusual stresses when in use.
  • a number of treatments of great interest from the technical and economic aspects were already known, such as high-temperature carburizing and direct quenching, it had hitherto been considered impossible or anyway too complex and costly to apply them to the production of track bushes for tracked vehicles (henceforth simply referred to as bushes).
  • the bush-manufacture cycles generally comprised a carburizing treatment at a temperature of 960 ⁇ 10°C in carburizing furnaces with natural gas fed directly into the retort.
  • Such unwanted structures could be avoided by a high complicated treatment involving, after carburization, a slow cooling in carburizing furnace to about 600°C, followed by a transfer to suitable chamber for further cooling to about 300°C; then air cooling to room temperature, followed by heating to 820-860°C, and quenching in water oil emulsion; then tempering of bushes ends at 550-600°C in induction furnace and subsequent cooling to obtain a surface hardness of 35-46 HRC; at last total stress relieving in soaking pit at 180-200°C for 1-2 hours.
  • the object of this invention is to simplify and reduce the cost of making bushes through a series of measures aimed at simplifying the plant reducing carburizing times, eliminating the heating for quenching and reducing energy consumption, particularly as regards methane, but maintaining the most suitable internal structure of the bushes.
  • the present invention provides for the use of techniques that, although actually known, such as high-temperature carburizing with furnace- produced atmosphere and direct quenching, are applied in an original manner to a product such as bushes and incorporated for the first time simultaneously in an optimized treatment cycle.
  • the process for the production of track bushes for tracked vehicles, from low-carbon boron steel, having a martensitic structure in the centre and on the surface with 5-8 ASTM austenitic grain, centre hardness between 32 and 44 HRC, surface hardness over 55 HRC and hardness of ends between 35 and 46 HRC, according to present invention comprises the following steps:
  • the carburizing temperature is preferably between 950 and 980°C.
  • the ends are preferably tempered in an induction furnace at a temperature of 550-600°C.
  • the manufacture cycle of the invention allows to save energy and to operate rapidly.
  • the saving in time is also marked. Indeed, if a carburizing depth of about 2.5 mm is chosen, with the traditional carburizing temperatures between 900 and 930°C the carburizing time ranges from 20 to 30 hours, which is almost twice that needed with the process as per the present invention.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Heat Treatment Of Articles (AREA)

Claims (3)

1. Procédé de production d'anneaux pour chenilles de véhicules chenillés, à paritr d'un acier au bore à faible teneur en carbone, ayant une structure martensitique au centre et en surface un grain austénitique 5-8 ASTM, ayant une dureté au centre comprise entre 32 et 44 HRC, une durété en surface supéreiure à 55 HRC, et une dureté aux extrémités comprise entre 35 et 46 HRC, ce procédé comprenant les phases suivantes:
-préchauffage des anneaux dans une chambre de prétraitement du four, alimentée par des gaz de combustion provenant de la chambre de cémentation suivante;
-transfert des anneaux dans la chambre de cémentation, où l'atmosphère de cémentation est produite in situ, et où le traitement s'effectue à une température dépassant 900°C;
-refroidissement dans une troisième chambre du four, à une température de 820-860°C, maintenue par des gaz de combustion sortant de la chambre de cémentation;
-extraction des anneaux un par un et trempe directe de chaque pièce isolément;
-revenu des extrémités des anneaux et refroidissement dans une émulsion;
-relaxation totale des contraintes des anneaux pendant 1 à 2 heures à 180-200°C en four continu alimenté par les gaz chauds évacués du four de cémentation.
2. Procédé selon la revendication 1, caractérisé par le fait que la température de cémentation est, de préférence, comprise entre 950 et 980°C.
3. Procédé selon la revendication 1, caractérisé par le fait qu'après la trempe directe des anneaux, les extrémités sont soumises à un traitement de revenu dans un four à induction, à une température de 550―600°C.
EP82830210A 1981-10-23 1982-07-21 Procédé de traitement de douille pour patin de chenille des tracteurs ou véhicules chenillés par carburation à température élevée dans une atmosphère carburée produite in situ, par trempe directe, revenu des bouts et recuit de détente Expired EP0079864B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT4955281 1981-10-23
IT49552/81A IT1171606B (it) 1981-10-23 1981-10-23 Procedimento per trattamento termico di cementazione ad alta temperatura con atmosfera cementante prodotta in situ tempra diretta rinvenimento alle estremita' di distensione totale di boccole per catenarie di trattori o mezzi cingolati

Publications (2)

Publication Number Publication Date
EP0079864A1 EP0079864A1 (fr) 1983-05-25
EP0079864B1 true EP0079864B1 (fr) 1987-11-25

Family

ID=11271005

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82830210A Expired EP0079864B1 (fr) 1981-10-23 1982-07-21 Procédé de traitement de douille pour patin de chenille des tracteurs ou véhicules chenillés par carburation à température élevée dans une atmosphère carburée produite in situ, par trempe directe, revenu des bouts et recuit de détente

Country Status (4)

Country Link
EP (1) EP0079864B1 (fr)
BR (1) BR8206000A (fr)
DE (1) DE3277732D1 (fr)
IT (1) IT1171606B (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60138065A (ja) * 1983-12-27 1985-07-22 Chugai Ro Kogyo Kaisha Ltd ガス浸炭焼入方法およびその連続式ガス浸炭焼入設備
JPH02169375A (ja) * 1988-12-21 1990-06-29 Topy Ind Ltd 履帯用ブッシングおよびその製造法
JPH03285020A (ja) * 1990-03-31 1991-12-16 Topy Ind Ltd 履帯用ブッシングの製造方法
IT1288690B1 (it) 1996-11-14 1998-09-23 Bruno Girardello Procedimento per il trattamento termico di boccole particolarmente per veicoli cingolati e simili

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE632935C (de) * 1931-05-16 1936-07-16 Benno Schilde Maschb Akt Ges Verfahren und Einrichtung zur Oberflaechenkohlung von Eisen und Stahl
US3227586A (en) * 1963-08-19 1966-01-04 Caterpillar Tractor Co Track pin bushing
CH615948A5 (fr) * 1974-03-18 1980-02-29 Hawera Probst Kg Hartmetall
US4049473A (en) * 1976-03-11 1977-09-20 Airco, Inc. Methods for carburizing steel parts
US4152177A (en) * 1977-02-03 1979-05-01 General Motors Corporation Method of gas carburizing

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Industrial Heating, september 1984, pages 22-23 *

Also Published As

Publication number Publication date
DE3277732D1 (en) 1988-01-07
IT8149552A0 (it) 1981-10-23
EP0079864A1 (fr) 1983-05-25
BR8206000A (pt) 1983-09-13
IT1171606B (it) 1987-06-10

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