EP0633078B1 - Method of fabricating a hollow steel body with an inner- and/or outer profiling - Google Patents

Method of fabricating a hollow steel body with an inner- and/or outer profiling Download PDF

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Publication number
EP0633078B1
EP0633078B1 EP94110048A EP94110048A EP0633078B1 EP 0633078 B1 EP0633078 B1 EP 0633078B1 EP 94110048 A EP94110048 A EP 94110048A EP 94110048 A EP94110048 A EP 94110048A EP 0633078 B1 EP0633078 B1 EP 0633078B1
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EP
European Patent Office
Prior art keywords
temperature
forming
flow
turning
temp
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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
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EP94110048A
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German (de)
French (fr)
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EP0633078A1 (en
Inventor
Helmut Wenzel
Bernhard Rolf
Heiner Jelenak
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METALL-SPEZIALROHR GmbH
Leifeld GmbH and Co
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METALL-SPEZIALROHR GmbH
Leifeld GmbH and Co
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Publication of EP0633078A1 publication Critical patent/EP0633078A1/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C5/00—Pointing; Push-pointing
    • B21C5/003—Pointing; Push-pointing of hollow material, e.g. tube
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21H—MAKING PARTICULAR METAL OBJECTS BY ROLLING, e.g. SCREWS, WHEELS, RINGS, BARRELS, BALLS
    • B21H5/00—Making gear wheels, racks, spline shafts or worms
    • B21H5/02—Making gear wheels, racks, spline shafts or worms with cylindrical outline, e.g. by means of die rolls
    • 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
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/22—Martempering
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
    • C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
    • 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
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite
    • 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
    • C21D9/32—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for gear wheels, worm wheels, or the like

Abstract

A hollow cylindrical preform made of steel contg. at least 0.2 wt % C and at least 3 wt % carbide forming elements such as Cr, Mo and B is heated in an inert atmosphere to its austenising temp and then cooled to a metastable austenite range which is below the recrystallisation temp. and above the martensite forming temp. It is then pressure rolled to produce the required profile and rapidly cooled to below the martensite forming temp. After martensitic transformation it is tempered at 400-600 deg C to precipitate the special carbides before being cooled to room temp. Pref., the forming tool, ie the roller is preheated prior to rolling. The temp. of the preform is constantly measured during rolling and the difference between the nominal and optimal temps is used to regulate the rolling speed during forming.

Description

Die Erfindung betrifft ein Verfahren zum Herstellen eines Hohlkörpers aus Stahl mit einer Innen- und/oder Außenprofilierung gemäß dem Oberbegriff des Anspruchs 1.The invention relates to a method for producing a hollow body made of steel with an inner and / or outer profile according to the preamble of claim 1.

Ein solches Verfahren ist aus der US-A 4 373 973 bekannt. Nach der Profilierung erfolgt dabei eine Abkühlung durch Luft. Da eine Anlaßbehandlung fehlt, kann die Gefügestruktur des Werkstücks ungleichmäßig sein.Such a method is known from US-A 4,373,973. After profiling, it is cooled by air. Because tempering treatment is lacking, the structure of the workpiece may be uneven.

Die DE 37 11 927 C1 beschreibt weiterhin ein Verfahren zur Herstellung von an ihrem Außenumfang in vorwiegend axialer Richtung profilierten, insbesondere gezahnten metallischen Hohlkörpern aus rotationssymmetrisch vorgeformten Hohlkörpern, wobei die Profilierung nach Zustellen wenigstens einer Profilrolle mittels dieser durch Drücken erzeugt wird und wobei schrittweise in radialer Richtung umgeformt wird.DE 37 11 927 C1 also describes a method for producing hollow hollow bodies which are profiled on their outer circumference in a predominantly axial direction, in particular toothed, from rotationally symmetrical preformed hollow bodies, the profiling being generated by pressing at least one profile roll by means of this, and gradually in a radial direction Direction is reshaped.

Außerdem sind spanende Verfahren zum Herstellen von Hohlkörpern der im Oberbegriff von Anspruch 1 genannten Art allgemein bekannt. Insbesondere sind hier Fräsen, z.B. Abrollfräsen, und Schleifen zu nennen. Allen diesen Verfahren haftet der Nachteil an, daß sie einen hohen Arbeits- und Zeitaufwand bei ihrer Ausführung erfordern, was zu hohen Herstellungskosten der damit hergestellten Produkte führt. Nachteilig ist weiterhin, daß die Festigkeit und Härte der so hergestellten Produkte begrenzt ist. Werden besondere Festigkeitsanforderungen, z.B. bei Zahnkränzen oder Zahnrädern, gestellt, dann ist ein zusätzliches Härten des Produktes nötig, was einen weiteren Arbeitsschritt erfordert und zusätzliche Herstellungskosten verursacht. Zudem wird durch das Härten die Maß- und Formgenauigkeit negativ beeinflußt, was oft eine Nachbearbeitung, z.B. ein Nachschleifen, erfordert, um die gewünschte Maßgenauigkeit zu erhalten.In addition, cutting methods for producing hollow bodies of the type mentioned in the preamble of claim 1 are generally known. Milling, for example roll-off milling, and grinding are particularly worth mentioning here. All these methods have the disadvantage that they require a lot of work and time in their execution, which leads to high manufacturing costs of the so produced Leads products. Another disadvantage is that the strength and hardness of the products thus produced is limited. If special strength requirements are placed, for example on gear rings or gear wheels, then additional hardening of the product is necessary, which requires a further work step and causes additional manufacturing costs. In addition, the dimensional and shape accuracy is adversely affected by hardening, which often requires reworking, for example regrinding, in order to obtain the desired dimensional accuracy.

Es stellt sich daher die Aufgabe, ein Verfahren der eingangs genannten Art anzugeben, das schnell und kostengünstig arbeitet und das gleichzeitig Produkte mit großer Maß- und Formgenauigkeit sowie hoher Härte und Festigkeit liefert.It is therefore the task of specifying a method of the type mentioned at the outset which works quickly and inexpensively and which at the same time delivers products with great dimensional and shape accuracy as well as high hardness and strength.

Die Lösung dieser Aufgabe gelingt erfindungsgemäß durch ein Verfahren der im Patentanspruch 1 genannten Art.This object is achieved according to the invention by a method of the type mentioned in claim 1.

Das erfindungsgemäße Verfahren bietet den Vorteil einer exakten Ausbildung der Profilierung bei sehr kurzen Bearbeitungszeiten. Die dabei erzielbaren Oberflächenhärten sind gleich oder sogar höher als die, die durch Härten erreichbar sind. Ist die Profilierung eine Verzahnung, dann wird zudem vorteilhaft eine höhere Festigkeit der Zahnkerne erzielt, als sie bei einem Einsatzstahl möglich ist. Dabei bleibt eine ausreichende Zähigkeit in jedem Fall erhalten. Ein nachgeschalteter Härteprozeß mit dem Risiko von Verminderungen der Maß- und Formgenauigkeit erübrigt sich damit, selbst bei höchsten Anforderungen an die Festigkeit des Produktes. Die hohe Qualität des Produktes wird schon mit relativ preiswerten Stählen als Material für den im Verfahren einzusetzenden Rohling erreicht, so daß auch von der Materialseite Kosteneinsparungen möglich sind. Weitere Kosteneinsparungen sind häufig möglich durch kleinere Dimensionierung der Produkte bei unverminderter Belastbarkeit und Haltbarkeit. Die hierbei gleichzeitig erzielbaren Gewichtseinsparungen sind insbesondere für die Kraftfahrzeug- und Luftfahrttechnik von Bedeutung.The method according to the invention offers the advantage of an exact formation of the profiling with very short processing times. The surface hardnesses that can be achieved are the same or even higher than those that can be achieved by hardening. If the profiling is toothing, then a higher strength of the tooth cores is advantageously achieved than is possible with case-hardening steel. Sufficient toughness is retained in any case. A subsequent hardening process with the risk of diminishing dimensional and shape accuracy is not necessary, even with the highest demands on the strength of the product. The high quality of the product is achieved with relatively inexpensive steels as the material for the blank to be used in the process, so that cost savings are also possible from the material side. Further cost savings are often possible due to the smaller dimensions of the products with undiminished resilience and durability. The weight savings that can be achieved at the same time are particularly important for automotive and aeronautical engineering.

Der Temperaturbereich des metastabilen Austenits liegt bei geeigneten Stählen beispielsweise bei etwa 500°C. Bei dieser Temperatur besitzt der Stahl ein besseres Fließverhalten als im kalten Zustand, so daß mit geringerer Kraft eine verbesserte Profilausbildung, insbesondere eine exaktere Zahnkopfausbildung an dem Werkstück durch vereinfachte und verbesserte vollständige Ausfüllung der Negativformen an dem Werkzeug ermöglicht werden. Das Abkühlen auf Raumtemperatur kann an der Luft erfolgen, gegebenenfalls an bewegter Luft, die die zu kühlenden verzahnten Hohlkörper gleichmäßig bestreicht.The temperature range of metastable austenite in suitable steels is, for example, around 500 ° C. At this temperature, the steel has a better flow behavior than in the cold state, so that with less force an improved profile formation, in particular a more precise tooth tip formation on the workpiece is made possible by simplified and improved complete filling of the negative molds on the tool. The cooling to room temperature can take place in air, if necessary in moving air, which evenly brushes the hollow hollow teeth to be cooled.

Ein in dem erfindungsgemäßen Verfahren vorteilhaft einsetzbarer Rohling besteht beispielsweise aus einem Stahl, der mindestens 0,2 - 0,6 Gew.-% Kohlenstoff und mindestens 3 Gew.-% der Elemente Chrom, Molybdän und Vanadium einzeln oder zu mehreren enthält. Ein Vertreter dieser Gruppe ist z.B. der Werkstoff 1.2344 = X 51 CrMo V 5 1 mit Gehalten von 0,5 % Kohlenstoff, 5 % Chrom, 1 % Molybdän und 0,5 % Vanadium.A blank which can advantageously be used in the process according to the invention consists, for example, of a steel which contains at least 0.2-0.6% by weight of carbon and at least 3% by weight of the elements chromium, molybdenum and vanadium individually or in groups. A representative of this group is, for example, the material 1.2344 = X 51 CrMo V 5 1 with contents of 0.5% carbon, 5% chromium, 1% molybdenum and 0.5% vanadium.

Weiter wird vorgeschlagen, daß die Werkzeuge für die Anformung der Profilierung vor dem Umformvorgang vorgewärmt werden. Hierdurch wird eine unerwünschte Abkühlung des zu profilierenden Hohlkörpers zu Beginn des Umformvorganges beim Drückwalzen vermieden.It is also proposed that the tools for the shaping of the profile be preheated before the forming process. This prevents undesired cooling of the hollow body to be profiled at the start of the forming process during the press rolling.

Schießlich besteht eine besonders vorteilhafte Ausgestaltung des Verfahrens darin, daß die Temperatur des Hohlkörpers während des Drückwalzens ständig gemessen, mit einer vorgegebenen Solltemperatur verglichen und das Ergebnis des Vergleiches zur Regelung der Drückwalzgeschwindigkeit hinzugezogen wird. Auf diese Art und Weise kann die Temperatur des Hohlkörpers während des Drückwalzens ohne weitere Kühl- oder Heizeinrichtungen im gewünschten Temperaturbereich, insbesondere im Temperaturbereich des metastabilen Austenits, gehalten werden, wobei eine Erhöhung der Drückwalzgeschwindigkeit eine erhöhte Energiezufuhr und damit eine Temperaturerhöhung und eine Verringerung der Drückwalzgeschwindigkeit eine verminderte Energiezufuhr und damit Temperaturabsenkung des Hohlkörpers bewirkt. Während des Umformvorganges gleichen sich also die durch das Drückwalzen in den Hohlkörper eingebrachte Umformenergie und die Energieabstrahlung und -ableitung aus dem Hohlkörper unter Aufrechterhaltung des gewünschten Temperaturniveaus zuverlässig aus.Finally, a particularly advantageous embodiment of the method is that the temperature of the hollow body is measured continuously during the pressure rolling, compared with a predetermined target temperature and the result of the comparison is used to regulate the pressure rolling speed. In this way, the temperature of the hollow body can be kept in the desired temperature range, in particular in the temperature range of the metastable austenite, without further cooling or heating devices, with an increase in the pressure rolling speed an increased energy supply and thus an increase in temperature and a reduction in the pressure rolling speed a reduced energy supply and thus lowering the temperature of the hollow body. During the forming process, therefore, the forming energy introduced into the hollow body by the pressure rolling and the energy radiation and dissipation from the hollow body are reliably balanced while maintaining the desired temperature level.

Drückmaschinen zur Durchführung des eigentlichen Drückwalzvorganges sind bekannt und brauchen daher nicht näher beschrieben zu werden. Sie können mit einer oder mehreren Umformrollen ausgerüstet werden.Spinning machines for carrying out the actual spinning rolling process are known and therefore do not need to be described in more detail. They can be equipped with one or more forming rolls.

Ein zur Erhitzung der Rohlinge aus einem austenitformhärtbarem Stahl auf Austenitisierungstemperatur verwendbarer Ofen ist vorteilhaft ein Schachtofen mit Schutzgas-Atmosphäre, z.B. Stickstoff, bei welchem für jeden entnommenen erhitzten Rohling ein noch nicht erhitzter Rohling eingegeben wird.A furnace which can be used to heat the blanks from an austenite-hardenable steel to the austenitizing temperature is advantageously a shaft furnace with a protective gas atmosphere, for example nitrogen, in which a blank which has not yet been heated for each heated blank removed Blank is entered.

Die Haltezeit auf Austenitisierungstemperatur und die Austenisierungstemperatur selbst ist vom verwendeten Stahltyp abhängig und beträgt ca. 20 bis 60 Minuten bei 900 bis 1050 °C.The holding time at the austenitizing temperature and the austenizing temperature itself depends on the type of steel used and is approx. 20 to 60 minutes at 900 to 1050 ° C.

Die Abkühlung von Austenitisierungstemperatur zur Umformtemperatur des metastabilen Austenits erfolgt bevorzugt unter inerter Atmosphäre.The cooling from the austenitizing temperature to the forming temperature of the metastable austenite is preferably carried out under an inert atmosphere.

Nach der Umformung erfolgt die Abkühlung an ruhender oder bewegter Luft; dabei erfolgt die Umwandlung in das martensitische Gefüge. Die sich daran anschließende Anlaßbehandlung bei Temperaturen zwischen 400 bis 600 °C erfolgt bevorzugt in einem Luftumwälzofen mit Haltezeiten zwischen einer und sechs Stunden; die sich daran anschließende Abkühlung von Anlaßtemperatur auf Raumtemperatur wird an ruhender Luft durchgeführt.After the forming, the cooling takes place in still or moving air; the transformation into the martensitic structure takes place. The subsequent tempering treatment at temperatures between 400 to 600 ° C is preferably carried out in an air circulation oven with holding times between one and six hours; the subsequent cooling from tempering temperature to room temperature is carried out in still air.

Als Beispiel für die auf die beschriebene Weise herzustellenden Teile seien folgende Abmessungen genannt:The following dimensions are mentioned as an example of the parts to be produced in the manner described:

Innenverzahnung: Innendurchmesser 10 bis 500 mm, Länge falls erforderlich bis 1500 mm, Zahnhöhe 1 bis 20 mm, Zahnbreite 1 bis 50 mm.Internal teeth: inner diameter 10 to 500 mm, length if necessary up to 1500 mm, tooth height 1 to 20 mm, tooth width 1 to 50 mm.

Es ist möglich, sowohl gerad- als auch schrägverzahnte Teile mit oder ohne Boden herzustellen.It is possible to produce both straight and helical parts with or without a bottom.

Claims (4)

  1. Method for fabricating a hollow steel body with an inner- and/or outer profiling by flow-turning particularly for fabricating a toothed ring out of a hollow cylindrical or pot-shaped blank wherein the flow-turning for the profiling is accomplished at a constant temperature in a metastable austenitic condition,
    characterized in
    - that the blank consists of an austenitic steel capable of form hardening with a sufficient amount of carbon and special carbide formers, and is heated to austeniting temperature in an inert atmosphere, and subsequently is cooled into the area of metastable austenite below the re-crystallisation and above the martensite forming temperature,
    - that in this area of the metastable austenite the flow-turning of the profiling is accomplished,
    - that following the flow-turning the profiled hollow body is quickly cooled to a temperature below the martensite forming temperature, and
    - that after the completed martensite forming the profiled hollow body is tempered at temperatures from 400 to 600°C for the precipitation of special carbides, and after completed tempering is cooled to room temperature.
  2. Method according to claim 1, characterized in that the blank consists of a steel comprising at least 0.2 % carbon by weight, and at least 3 % by weight of the special carbide forming elements chromium, molybdenum, and Vanadium either single or in a plurality.
  3. Method according to claim 1 or 2, characterized in that the tools for the forming of the profile are pre-heated prior to the forming process.
  4. Method according to one of the claims 1 to 3, characterized in that the temperature of the hollow body is continuously measured during the flow-turning, and is compared with a pre-set nominal temperature, and the result of the comparison is used for controlling the flow-turning speed.
EP94110048A 1993-07-10 1994-06-29 Method of fabricating a hollow steel body with an inner- and/or outer profiling Expired - Lifetime EP0633078B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4323167 1993-07-10
DE4323167A DE4323167C1 (en) 1993-07-10 1993-07-10 Producing steel hollow bodies by rolling - combined with austenitic heat treatment

Publications (2)

Publication Number Publication Date
EP0633078A1 EP0633078A1 (en) 1995-01-11
EP0633078B1 true EP0633078B1 (en) 1996-10-23

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP94110048A Expired - Lifetime EP0633078B1 (en) 1993-07-10 1994-06-29 Method of fabricating a hollow steel body with an inner- and/or outer profiling

Country Status (5)

Country Link
EP (1) EP0633078B1 (en)
JP (1) JPH07185714A (en)
AT (1) ATE144445T1 (en)
DE (2) DE4323167C1 (en)
ES (1) ES2095110T3 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0735150A2 (en) 1995-03-29 1996-10-02 Toyota Jidosha Kabushiki Kaisha Method for producing cast iron gear

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Publication number Priority date Publication date Assignee Title
DE4403897C2 (en) * 1994-02-08 1995-12-07 Peter Dipl Ing Tess Process for hot drawing the ends of hollow workpieces by roller burnishing
EP1092489B1 (en) * 1999-10-15 2002-09-18 Rothe Erde GmbH Method for manufacturing a roller for tracked vehicle
DE102004051885A1 (en) * 2004-10-26 2006-04-27 Fag Kugelfischer Ag & Co. Ohg Mechanically load-bearing actuator or bearing component made of mechanically hardened steel
CZ201190A3 (en) * 2011-02-18 2012-01-18 Západoceská Univerzita V Plzni Process for producing hollow high-strength bodies of multiphase martensitic steels
CZ2011612A3 (en) 2011-09-30 2013-07-10 Západoceská Univerzita V Plzni Method of achieving TRIP microstructure in steels by deformation heat
GB201316829D0 (en) 2013-09-23 2013-11-06 Rolls Royce Plc Flow Forming method
CN111349761B (en) * 2020-05-11 2021-09-21 南京红宝机械刀具有限公司 High-frequency heat treatment process for cutter
DE102021109866B3 (en) * 2021-04-20 2022-08-11 Thyssenkrupp Steel Europe Ag Process for manufacturing a pressure vessel

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FR1323588A (en) * 1962-02-23 1963-04-12 Tech Integrale Process for manufacturing age hardening austeno-martensitic stainless steel gears
DE2225390A1 (en) * 1972-05-25 1973-12-06 Messerschmitt Boelkow Blohm DEVICE AND METHOD FOR MANUFACTURING DEFINED WALL THICKNESS CHANGES IN A ROTATIONAL SYMMETRIC HOLLOW BODY
US4373973A (en) * 1981-11-16 1983-02-15 International Harvester Co. Method of manufacture of high performance gears
JPS603935A (en) * 1983-06-22 1985-01-10 Fuji Heavy Ind Ltd Continuous rolling and surface hardening method of steel parts
DD232210A1 (en) * 1984-07-20 1986-01-22 Tech Hochschule PROCESS FOR PROFILE GENERATION BY WASTE PRESSURE
US4637844A (en) * 1985-07-08 1987-01-20 Tocco, Inc. Method for heat treating ferrous parts
DE3711927C1 (en) * 1987-04-13 1988-10-13 Leifeld & Co Method for the production of metal hollow bodies with profiles running in the axial direction on their outer circumference, especially teeth, and an apparatus for carrying out the method
JPH0593225A (en) * 1991-09-30 1993-04-16 Nissan Motor Co Ltd Production of cast iron gear

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0735150A2 (en) 1995-03-29 1996-10-02 Toyota Jidosha Kabushiki Kaisha Method for producing cast iron gear

Also Published As

Publication number Publication date
EP0633078A1 (en) 1995-01-11
ATE144445T1 (en) 1996-11-15
JPH07185714A (en) 1995-07-25
DE59400878D1 (en) 1996-11-28
DE4323167C1 (en) 1994-05-19
ES2095110T3 (en) 1997-02-01

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