EP0483182B1 - Process for hardening the cutting edges of saws, knives and cutting tools - Google Patents

Process for hardening the cutting edges of saws, knives and cutting tools Download PDF

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Publication number
EP0483182B1
EP0483182B1 EP90910482A EP90910482A EP0483182B1 EP 0483182 B1 EP0483182 B1 EP 0483182B1 EP 90910482 A EP90910482 A EP 90910482A EP 90910482 A EP90910482 A EP 90910482A EP 0483182 B1 EP0483182 B1 EP 0483182B1
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Prior art keywords
plasma jet
cutting edge
plasma
axis
jet
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German (de)
French (fr)
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EP0483182A1 (en
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Albert Schuler
Wladimir Tokmakov
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Priority claimed from AT245189A external-priority patent/AT392981B/en
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    • 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
    • C21D9/22—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for drills; for milling cutters; for machine cutting tools
    • 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
    • C21D1/06—Surface hardening
    • C21D1/09—Surface hardening by direct application of electrical or wave energy; by particle radiation
    • 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
    • C21D9/18—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for knives, scythes, scissors, or like hand cutting tools
    • 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
    • C21D9/24—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for saw blades

Definitions

  • the invention relates to a method for hardening the cutting edges of saws, in particular for woodworking, as well as knives or punching tools for wood, paper, cardboard, plastic, leather or textile processing by means of an energy beam which scans the areas to be hardened Tools is guided.
  • Saws, knives or punching tools for the mentioned area of application wear on the cutting edges.
  • the service life of these tools depends on the quality of the cutting edge (material used, hardening process), the material to be cut and the cutting performance. After the end of the service life, these tools are either reground or scrapped.
  • Many types of saws, knives and punching tools are made of carbon steel, which can be easily hardened by heating and subsequent rapid cooling. However, since such hardening is always associated with a decrease in toughness, great hardness is only desired in the area of the cutting edges.
  • the remaining parts of a saw, a knife or a punching tool should have a lower hardness but a higher toughness.
  • Another well-known hardening process is inductive hardening. After grinding the cutting edge, the cutting area is heated by an eddy current generated by a high-frequency alternating magnetic field and hardened by rapid cooling.
  • the object of the present invention is to provide a method for hardening the cutting edges of saws, knives and punching tools, in which an energy beam which is simple to produce and inexpensive to use is used.
  • a plasma jet is used as the energy jet, the plasma jet being guided at a relative speed with respect to the tool of 5 to 100 mm / sec and the distance between the outlet nozzle of the plasma torch and the cutting edge in the range between 2 and 14 mm and where the power of the plasma jet is between 1 and 10 kW, and the diameter at the outlet nozzle of the plasma torch is between 3 and 7 mm.
  • the heating and cooling speed is adapted to optimal values for different material thicknesses and cutting edge angles.
  • the feed rate should be chosen higher, otherwise the cooling rate is too low due to the limited heat dissipation into the base material for sufficiently high hardening.
  • the feed speed can be selected to achieve larger hardness zones.
  • Plasma jets are produced by ionization of argon or nitrogen or mixed gases.
  • the ionization takes place by an electric arc discharge or by excitation with a high-frequency electromagnetic field.
  • suitable Shaping of the electrodes or nozzles creates a jet, in the axis of which temperatures of up to 15,000 ° C can be reached.
  • a local area of the cutting edge heats up at rates of up to 5000 K / sec.
  • the cutting edge cools by self-quenching, i.e. by dissipating heat into the base material of the tool at cooling rates of up to 1000 K / sec. This creates a fine-grained martensite structure with hardnesses up to 1000 HV (Vickers hardness).
  • a knife or a punching tool is preferably guided through the plasma jet by mechanical movement along the cutting edge, the axis of the plasma jet coinciding with the axis of symmetry of the cutting edge. In this way, the most uniform possible heat is achieved over the flanks of the cutting edge.
  • the plasma jet is guided across the back of the tooth in the area of the upper cutting edge by mechanical movement of the plasma torch across the saw blade. In this way, the most uniform possible heat exposure over the entire length of the cutting edge Tooth tip achieved. With certain saw shapes, on the other hand, it is advantageous and technically simpler to guide the plasma torch along the saw blade without transverse movement.
  • An electromagnetic deflection by means of a coil, which is arranged in the area between the cathode and the lower edge of the nozzle, enables a defined broadening of the plasma jet and thus an adaptation to the tooth geometry (for example with set saws).
  • the difference to the known method of electromagnetically deflecting the plasma jet during the reflow treatment (build-up welding) is that the electromagnetic field is affected in the area between the lower edge of the nozzle and the workpiece surface. With this method, a focal spot of the arc must be on the workpiece surface. This known method does not work in plasma hardening, since the arc must burn between the cathode and the lower edge of the nozzle.
  • the axis of the plasma jet is at a certain angle (e.g. 90 °, 135 ° or half the cutting edge angle) to the axis of symmetry of the cutting edge.
  • a certain angle e.g. 90 °, 135 ° or half the cutting edge angle
  • a distribution of the hardness zone that is asymmetrical with respect to the axis of symmetry can be achieved and thus an adaptation to special wear situations.
  • knife blades with a thickness of more than 5 mm a good adjustment of the hardness zone to different cutting edge geometries is possible.
  • Fig. 1 shows schematically the basic arrangement of the plasma system using the example of a saw hardening.
  • the plasma torch 1 uses an electrical arc discharge to generate a plasma jet 2 from the gas supplied, which emerges at the outlet nozzle of the plasma torch 1.
  • the distance between the exit nozzle and the cutting edge is a.
  • the plasma jet is directed onto the tooth tip 5 of a sawtooth 4 and heats this area. After the end of the energy exposure, the heated area cools down rapidly and hardens. Then the saw blade 3 is moved further and the plasma jet 2 is directed onto the tooth tip 5a of the following tooth 4a.
  • Figure 2 shows the area of the tooth tip of a saw blade in detail in an axonometric representation.
  • the plasma jet 2 has a diameter d and is moved at a relative speed v either along the cutting edge 6 or in the direction of the teeth.
  • FIG 3 shows schematically the basic arrangement of the plasma system using the example of a knife hardening.
  • the plasma jet is directed onto the cutting edge 9 of the knife at an angle ⁇ and is moved along this edge at the speed v, this edge being heated. After the end of the energy exposure, the heated area quickly cools down and hardens by self-quenching.
  • FIG. 4 schematically shows a cross section through the plasma torch in the area of the outlet nozzle.
  • Example 1 Hardening a frame saw.
  • Example 2 Hardening a circular saw.
  • Example 4 Hardening a punch knife for leather and textiles:
  • Material steel strip CK60 (material no.1.1221) Thickness: 2 mm Untreated hardness: 300 HV (Vickers) Plasma power (kW) 1 2nd 4th Beam diameter (d in mm) 4th 4th 4th Distance (a in mm) 4th 6 8th Angle between the plasma axis and the cutting edge axis (degrees) 0 0 0 Feed speed (v in mm / sec) 25th 35 50 Gas flow (l / min) 5 5 5 5 maximum hardness (HV) 860 890 940
  • Example 5 Hardening a planer knife for woodworking

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Physics & Mathematics (AREA)
  • Arc Welding In General (AREA)
  • Heat Treatment Of Articles (AREA)
  • Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)
  • Laser Beam Processing (AREA)
  • Turning (AREA)
  • Polishing Bodies And Polishing Tools (AREA)
  • Nonmetal Cutting Devices (AREA)

Abstract

A process is disclosed for hardening the cutting edges of saws, knives and cutting tools, in particular for processing wood, paper, cardboard, plastic materials, leather and textiles, by means of an energy beam guided over the areas to be hardened of the tool. In order to obtain optimal hardness, a plasma beam is used as energy beam. The plasma beam (2) is guided with a relative speed (v) with respect to the cutting edge of the tool between 5 and 100 mm/sec., the gap between the outlet nozzle of the plasma torch (1) and the cutting edge extends between 2 and 14 mm, the power of the plasma beam is comprised between 1 and 10 kW, and the diameter (d) of the outlet nozzle of the plasma torch (1) is comprised between 3 and 7 mm.

Description

Die Erfindung betrifft ein Verfahren zum Härten der Schneidkanten von Sägen, insbesonders für die Holzbearbeitung, sowie Messern oder Stanzwerkzeugen für die Holz-, Papier-, Kartonagen-, Kunststoff-, Leder- oder Textilienbearbeitung mittels eines Energiestrahles, der über die zu härtenden Bereiche dieser Werkzeuge geführt wird. Sägen, Messer oder Stanzwerkzeuge für den genannten Einsatzbereich verschleißen an den Schneidkanten. Die Standzeit dieser Werkzeuge hängt ab von der Qualität der Schneide (verwendetes Material, Härteverfahren), vom Schneidgut und von der Schnittleistung. Nach dem Ende der Standzeit werden diese Werkzeuge entweder nachgeschliffen oder verschrottet. Viele Sägen-, Messer- und Stanzwerkzeugtypen bestehen aus Kohlenstoffstahl, der durch Erwärmung und anschließender schneller Abkühlung leicht gehärtet werden kann. Da eine solche Härtung jedoch stets mit der Abnahme der Zähigkeit verbunden ist, ist eine große Härte lediglich im Bereich der Schneidkanten erwünscht. Die übrigen Teile einer Säge, eines Messers oder eines Stanzwerkzeuges sollen eine geringere Härte, dafür jedoch eine größere Zähigkeit aufweisen.The invention relates to a method for hardening the cutting edges of saws, in particular for woodworking, as well as knives or punching tools for wood, paper, cardboard, plastic, leather or textile processing by means of an energy beam which scans the areas to be hardened Tools is guided. Saws, knives or punching tools for the mentioned area of application wear on the cutting edges. The service life of these tools depends on the quality of the cutting edge (material used, hardening process), the material to be cut and the cutting performance. After the end of the service life, these tools are either reground or scrapped. Many types of saws, knives and punching tools are made of carbon steel, which can be easily hardened by heating and subsequent rapid cooling. However, since such hardening is always associated with a decrease in toughness, great hardness is only desired in the area of the cutting edges. The remaining parts of a saw, a knife or a punching tool should have a lower hardness but a higher toughness.

Bekannte Verfahren zur partiellen Härtung der Schneidkanten verwenden Elektronen- oder Laserstrahlen als Energiequelle. Nachteilig bei der Härtung mit Elektronenstrahlen oder Laserstrahlen sind die aufwendigen Vorrichtungen die zur Durchführung solcher Verfahren benötigt werden. Aus diesem Grund haben sich solche Verfahren in der Praxis bisher kaum durchgesetzt.Known methods for partially hardening the cutting edges use electron or laser beams as the energy source. A disadvantage of curing with electron beams or laser beams is the complex devices that are required to carry out such processes. For this reason, such procedures have so far hardly become established in practice.

Ein weiters bekanntes Härtungsverfahren ist die Induktive Härtung. Nach dem Schleifen der Schneidkante wird der Schneidenbereich durch einen Wirbelstrom, erzeugt durch ein hochfrequentes magnetisches Wechselfeld, erhitzt und durch rasche Abkühlung gehärtet.Another well-known hardening process is inductive hardening. After grinding the cutting edge, the cutting area is heated by an eddy current generated by a high-frequency alternating magnetic field and hardened by rapid cooling.

Weiters ist es aus der WO 83/00051 bekannt, eine oberflächige Härtung flächiger Bereiche mittels eines Plasmastrahles durchzuführen. Eine Härtung von Schneidkanten mittels Plasmastrahlen wurde bisher noch nicht in Betracht gezogen, da solche Plasmastrahlen eine zu geringe Stabilität aufweisen.Furthermore, it is known from WO 83/00051 to carry out a surface hardening of flat areas by means of a plasma jet. A hardening of cutting edges by means of plasma jets has not yet been considered, because such plasma beams are not stable enough.

Bei Sägen ist das Aufschweißen von Stellite auf die Zahnspitzen bekannt. Das aufgeschweißte Stellite-Material wird anschließend auf die gewünschte Zahnspitzenform zugeschliffen. Dieses Verfahren ist jedoch sehr aufwendig. Aufgabe der vorliegenden Erfindung ist es, ein Verfahren zum Härten der Schneidkanten von Sägen, Messern und Stanzwerkzeugen anzugeben, bei dem ein einfach herzustellender und kostengünstig zu betreibender Energiestrahl verwendet wird.In the case of saws, Stellite is known to be welded onto the tooth tips. The welded stellite material is then ground to the desired tooth tip shape. However, this process is very complex. The object of the present invention is to provide a method for hardening the cutting edges of saws, knives and punching tools, in which an energy beam which is simple to produce and inexpensive to use is used.

Erfindungsgemäß ist daher vorgesehen, daß als Energiestrahl ein Plasmastrahl verwendet wird, wobei der Plasmastrahl mit einer Relativgeschwindigkeit in Bezug auf das Werkzeug von 5 bis 100 mm/sek geführt wird und wobei der Abstand der Austrittsdüse des Plasmabrenners von der Schneidkante im Bereich zwischen 2 und 14 mm liegt und wobei weiters die Leistung des Plasmastrahles zwischen 1 und 10 kW liegt, sowie der Durchmesser bei der Austrittsdüse des Plasmabrenners zwischen 3 und 7 mm liegt.According to the invention, it is therefore provided that a plasma jet is used as the energy jet, the plasma jet being guided at a relative speed with respect to the tool of 5 to 100 mm / sec and the distance between the outlet nozzle of the plasma torch and the cutting edge in the range between 2 and 14 mm and where the power of the plasma jet is between 1 and 10 kW, and the diameter at the outlet nozzle of the plasma torch is between 3 and 7 mm.

Überraschenderweise wurde festgestellt, daß es bei genau abgestimmter Konstellation von Parametern durchaus möglich ist, einen Plasmastrahl zum Härten der Schneidkanten dieser Werkzeug einzusetzen, wobei es weiters nur bei diesen Parametern möglich ist, die Härtung durch Selbstabschreckung, also ohne zusätzliche Abkühlung, etwa durch Luft oder Wasser, zu erreichen.Surprisingly, it was found that, with a precisely coordinated constellation of parameters, it is entirely possible to use a plasma jet to harden the cutting edges of this tool, although it is also only possible for these parameters to harden by self-quenching, i.e. without additional cooling, for example by air or Water to reach.

Vorteilhafte weitere Merkmale des erfindungsgemäßen Verfahrens nennen die abhängigen Ansprüche.The dependent claims call advantageous further features of the method according to the invention.

Mit der Vorschubgeschwindigkeit v wird die Aufheiz- und Abkühlgeschwindigkeit auf optimale Werte an unterschiedliche Materialdicken und Schneidenwinkel angepaßt. Bei dünneren Blattstärken, insbesonders unter 3 mm, bzw. bei kleineren Schneidenwinkeln, insbesonders unter 25°, ist die Vorschubgeschwindigkeit höher zu wählen, da sonst die Kühlrate infolge der beschränkten Wärmeableitung in das Grundmaterial für eine ausreichend höhe Härtung zu klein ist. Bei größeren Blattstärken bzw. Schneidenwinkeln kann die Vorschubgeschwindigkeit zur Erzielung größerer Härtezonen kleiner gewählt werden.With the feed speed v the heating and cooling speed is adapted to optimal values for different material thicknesses and cutting edge angles. For thinner sheet thicknesses, especially less than 3 mm, or for smaller cutting angles, especially less than 25 °, the feed rate should be chosen higher, otherwise the cooling rate is too low due to the limited heat dissipation into the base material for sufficiently high hardening. With larger blade thicknesses or cutting angles, the feed speed can be selected to achieve larger hardness zones.

Plasmastrahlen werden durch Ionisation von Argon oder Stickstoff bzw. Mischgasen hergestellt. Die Ionisation erfolgt durch eine elektrische Bogenentladung oder durch Anregung mit einem hochfrequenten elektromagnetischen Feld. Durch geeignete Formgebung der Elektroden bzw. der Düsen wird ein Strahl erzielt, in dessen Achse Temperaturen bis 15.000°C erreicht werden.Plasma jets are produced by ionization of argon or nitrogen or mixed gases. The ionization takes place by an electric arc discharge or by excitation with a high-frequency electromagnetic field. By suitable Shaping of the electrodes or nozzles creates a jet, in the axis of which temperatures of up to 15,000 ° C can be reached.

Wird ein solcher Plasmastrahl mit den erfindungsgemäßen Parametern über die geschliffene Schneidkante einer Säge, eines Messers oder eines Stanzwerkzeuges geführt, so erhitzt sich ein lokaler Bereich der Schneidkante mit Erwärmungsraten bis 5000 K/sek. Nach der Beendigung der Energiezufuhr kühlt die Schneidkante durch Selbstabschreckung, d.h. durch Wärmeabfuhr in das Grundmaterial des Werkzeuges mit Abkühlgeschwindigkeiten bis 1000 K/sek ab. Dabei entsteht ein feinkörniges Martensitgefüge mit Härten bis 1000 HV (Vickers-Härte).If such a plasma jet with the parameters according to the invention is guided over the ground cutting edge of a saw, knife or punching tool, then a local area of the cutting edge heats up at rates of up to 5000 K / sec. Upon completion of the energy supply, the cutting edge cools by self-quenching, i.e. by dissipating heat into the base material of the tool at cooling rates of up to 1000 K / sec. This creates a fine-grained martensite structure with hardnesses up to 1000 HV (Vickers hardness).

Kritisch ist jedoch bei solchen Verfahren, daß die Schneidkante während der Wärmebehandlung nicht aufschmelzen darf. Trotzdem muß eine ausreichend hohe Erwärmung im Bereich der Schneidkante gegeben sein, um die gewünschte Aushärtung sicherzustellen. Dies wird nur bei den oben angegebenen Parameterkonstellationen erreicht.What is critical in such processes, however, is that the cutting edge must not melt during the heat treatment. Nevertheless, there must be sufficient heating in the area of the cutting edge to ensure the desired hardening. This is only achieved with the parameter constellations specified above.

Besonders günstige Bedingungen für die Härtung ergeben sich bei folgenden Werten: Leistung des Plasmastrahles: 1 bis 5 kW Durchmesser des Strahles bei der Austrittsdüse des Plasmabrenners: 4 bis 5,5 mm Abstand der Austrittsdüse des Plasmabrenners von der Schneidkante : 3 bis 9 mm Relativgeschwindigkeit des Plasmastrahles bezüglich der Schneidkante: 15 bis 50 mm/sek Particularly favorable conditions for curing result from the following values: Power of the plasma beam: 1 to 5 kW Diameter of the jet at the outlet of the plasma torch: 4 to 5.5 mm Distance from the plasma torch outlet nozzle to the cutting edge: 3 to 9 mm Relative speed of the plasma jet with respect to the cutting edge: 15 to 50 mm / sec

Vorzugsweise wird ein Messer oder ein Stanzwerkzeug durch mechanische Bewegung entlang der Schneidkante durch den Plasmastrahl geführt, wobei die Achse des Plasmastrahles mit der Symmetrieachse der Schneidkante zusammenfällt. Auf diese Weise wird eine möglichst gleichmäßige Wärmeeinwirkung über Flanken der Schneidkante erzielt. Bei Sägen wird der Plasmastrahl durch mechanische Bewegung des Plasmabrenners quer zum Sägeblatt über die Zahnrückseite im Bereich der oberen Schneidkante geführt. Auf diese Weise wird eine möglichst gleichmäßige Wärmeeinwirkung über die gesamte Länge der Schneidkante der Zahnspitze erzielt. Bei bestimmten Sägeformen ist es hingegen vorteilhaft und technisch einfacher, den Plasmabrenner ohne Querbewegung entlang des Sägeblattes zu führen. Durch eine elektromagnetische Ablenkung mittels einer Spule, die im Bereich zwischen Kathode und Düsenunterkante angeordnet ist, ist eine definierte Verbreiterung des Plasmastrahles und damit eine Anpassung an die Zahngeometrie (z.B. bei geschränkten Sägen) möglich. Der Unterschied zur bekannten Methode, den Plasmastrahl beim Aufschmelzbehandeln (Auftragsschweißen) elektromagnetisch abzulenken, besteht darin, daß dort die Einwirkung des elektromagnetischen Feldes im Bereich zwischen Düsenunterkante und Werkstückoberfläche erfolgt. Bei diesem Verfahren muß sich ein Brennfleck des Lichtbogens auf der Werkstückoberfläche befinden. Diese bekannte Methode funktioniert bei der Plasmahärtung nicht, da hier der Lichtbogen zwischen Kathode und Düsenunterkante brennen muß.A knife or a punching tool is preferably guided through the plasma jet by mechanical movement along the cutting edge, the axis of the plasma jet coinciding with the axis of symmetry of the cutting edge. In this way, the most uniform possible heat is achieved over the flanks of the cutting edge. In the case of saws, the plasma jet is guided across the back of the tooth in the area of the upper cutting edge by mechanical movement of the plasma torch across the saw blade. In this way, the most uniform possible heat exposure over the entire length of the cutting edge Tooth tip achieved. With certain saw shapes, on the other hand, it is advantageous and technically simpler to guide the plasma torch along the saw blade without transverse movement. An electromagnetic deflection by means of a coil, which is arranged in the area between the cathode and the lower edge of the nozzle, enables a defined broadening of the plasma jet and thus an adaptation to the tooth geometry (for example with set saws). The difference to the known method of electromagnetically deflecting the plasma jet during the reflow treatment (build-up welding) is that the electromagnetic field is affected in the area between the lower edge of the nozzle and the workpiece surface. With this method, a focal spot of the arc must be on the workpiece surface. This known method does not work in plasma hardening, since the arc must burn between the cathode and the lower edge of the nozzle.

Eine Verringerung des Energiebedarfes beim Härten kann dadurch erreicht werden, daß der Plasmastrahl im Impulsbetrieb arbeitet, mit einer Impulsfrequenz f, mit f=Vorschubgeschwindigkeit des Sägeblattes dividiert durch den Zahnabstand, wobei die Impulsdauer im Bereich von 0,2 bis 0,8 sek. liegt.A reduction in the energy requirement during hardening can be achieved in that the plasma jet operates in pulse mode, with a pulse frequency f, with f = feed speed of the saw blade divided by the tooth spacing, the pulse duration being in the range from 0.2 to 0.8 seconds. lies.

Bei Messern ist es möglich, daß die Achse des Plasmastrahles einen bestimmten Winkel (z.B. 90°, 135° oder die Hälfte des Schneidenwinkels) zur Symmetrieachse der Schneidkante einnimmt. Man kann so eine zur Symmetrieachse unsymmetrische Verteilung der Härtezone und damit eine Anpassung an spezielle Verschleißsituationen erreichen. Insbesonders bei Messerblättern mit einer Dicke über 5 mm ist damit eine gute Anpassung der Härtezone an verschiedene Schneidengeometrien möglich.With knives, it is possible that the axis of the plasma jet is at a certain angle (e.g. 90 °, 135 ° or half the cutting edge angle) to the axis of symmetry of the cutting edge. In this way, a distribution of the hardness zone that is asymmetrical with respect to the axis of symmetry can be achieved and thus an adaptation to special wear situations. Particularly with knife blades with a thickness of more than 5 mm, a good adjustment of the hardness zone to different cutting edge geometries is possible.

Im Folgenden wird die Erfindung anhand der beigefügten Figuren näher erläutert:
   Die Fig. 1 zeigt schematisch die prinzipielle Anordnung der Plasmaanlage am Beispiel einer Sägehärtung.The invention is explained in more detail below with reference to the attached figures:
Fig. 1 shows schematically the basic arrangement of the plasma system using the example of a saw hardening.

Der Plasmabrenner 1 erzeugt aus dem zugeführten Gas mit Hilfe einer elektrischen Bogenentladung einen Plasmastrahl 2, der an der Austrittsdüse des Plasmabrenners 1 austritt. Der Abstand zwischen der Austrittsdüse und der Schneidkante ist a. Der Plasmastrahl wird auf die Zahnspitze 5 eines Sägezahnes 4 gerichtet und erhitzt diesen Bereich. Nach Beendigung der Energieeinwirkung kühlt der erhitzte Bereich rasch ab und härtet. Danach wird das Sägeblatt 3 weiterbewegt und der Plasmastrahl 2 auf die Zahnspitze 5a des folgenden Zahnes 4a gerichtet.The plasma torch 1 uses an electrical arc discharge to generate a plasma jet 2 from the gas supplied, which emerges at the outlet nozzle of the plasma torch 1. The distance between the exit nozzle and the cutting edge is a. The plasma jet is directed onto the tooth tip 5 of a sawtooth 4 and heats this area. After the end of the energy exposure, the heated area cools down rapidly and hardens. Then the saw blade 3 is moved further and the plasma jet 2 is directed onto the tooth tip 5a of the following tooth 4a.

Figur 2 zeigt den Bereich der Zahnspitze eines Sägeblattes im Detail in axonometrischer Darstellung. Der Plasmastrahl 2 hat einen Durchmesser d und wird mit einer Relativgeschwindigkeit v entweder entlang der Schneidkante 6 oder in Richtung der Zähnung bewegt.Figure 2 shows the area of the tooth tip of a saw blade in detail in an axonometric representation. The plasma jet 2 has a diameter d and is moved at a relative speed v either along the cutting edge 6 or in the direction of the teeth.

Figur 3 zeigt schematisch die prinzipielle Anordnung der Plasmaanlage am Beispiel einer Messerhärtung. Der Plasmastrahl wird unter einem Winkel α auf die Schneidkante 9 des Messers gerichtet und mit der Geschwindigkeit v entlang dieser Kante bewegt, wobei diese Kante erhitzt wird. Nach Beendigung der Energieeinwirkung kühlt der erhitzte Bereich durch Selbstabschreckung rasch ab und härtet.Figure 3 shows schematically the basic arrangement of the plasma system using the example of a knife hardening. The plasma jet is directed onto the cutting edge 9 of the knife at an angle α and is moved along this edge at the speed v, this edge being heated. After the end of the energy exposure, the heated area quickly cools down and hardens by self-quenching.

Figur 4 zeigt schematisch eine Querschnitt durch den Plasmabrenner im Bereich der Austrittsdüse. Eine Elektromagnet 10, angeordnet im Bereich zwischen Kathode 8 und Düsenunterkante 11 bewirkt durch hochfrequente Ablenkung des Lichtbogens innerhalb des Düsenbereiches eine Aufweitung des Plasmastrahles 2.FIG. 4 schematically shows a cross section through the plasma torch in the area of the outlet nozzle. An electromagnet 10, arranged in the area between the cathode 8 and the lower edge 11 of the nozzle, causes the plasma jet 2 to expand by high-frequency deflection of the arc within the area of the nozzle.

Die folgenden Ausführungsbeispiele sollen den Einsatz des Verfahrens näher erläutern:The following exemplary embodiments are intended to explain the use of the method in more detail:

Beispiel 1: Härtung einer Gattersäge.Example 1: Hardening a frame saw.

Material: Bandstahl B412 (legierter Stahl mit 0,85% C, 0,3% Si, 0,3% Mn, 0,5% Cr, 0,4% Ni, 0,25% V) 45 Zähne, Zahnabstand 30 mm,
Breite b der Schneidkante: 3,5 mm,
Härte in unbehandeltem Zustand 420 HV. Plasmaleistung (kW) 2,5 3,5 2,0 Strahldurchmesser (d in mm) 4,0 4,0 4,0 Abstand (a im mm) 5,0 6,0 4,0 Vorschubgeschwindigkeit (v in mm/sek) 25 30 20 Gasdurchfluß (l/min) 7 10 7 maximale Härte (HV) 920 940 900
Praktische Schneidversuche in Sägewerken ergaben eine Erhöhung der Standzeit um den Faktor 5.Material: steel strip B412 (alloy steel with 0.85% C, 0.3% Si, 0.3% Mn, 0.5% Cr, 0.4% Ni, 0.25% V) 45 teeth, tooth spacing 30 mm ,
Width b of the cutting edge: 3.5 mm,
Untreated hardness 420 HV. Plasma power (kW) 2.5 3.5 2.0 Beam diameter (d in mm) 4.0 4.0 4.0 Distance (a in mm) 5.0 6.0 4.0 Feed speed (v in mm / sec) 25th 30th 20th Gas flow (l / min) 7 10th 7 maximum hardness (HV) 920 940 900
Practical cutting tests in sawmills resulted in an increase in tool life by a factor of 5.

Beispiel 2: Härtung einer Kreissäge.Example 2: Hardening a circular saw.

Material: Sägestahl B412, 50 Zähne, Zahnabstand 30 mm,
Breite b der Schneidkante: 4,0 mm,
Härte in unbehandeltem Zustand 410 HV. Plasmaleistung (kW) 3,0 Strahldurchmesser (d in mm) 4,0 Abstand (a im mm) 5,0 Vorschubgeschwindigkeit (v in mm/sek) 30 Gasdurchfluß (l/min) 8 maximale Härte (HV) 900 Material: saw steel B412, 50 teeth, tooth spacing 30 mm,
Width b of the cutting edge: 4.0 mm,
Untreated hardness 410 HV. Plasma power (kW) 3.0 Beam diameter (d in mm) 4.0 Distance (a in mm) 5.0 Feed speed (v in mm / sec) 30th Gas flow (l / min) 8th maximum hardness (HV) 900

Beispiel 3: Härtung einer BandsägeExample 3: Hardening a band saw

Material Sägestahl B412, Bandlänge 6 m, Zahnabstand 15 mm,
Breite b der Scneidkante: 1,5 mm,
Härte in unbehandeltem Zustand 410 HV. Plasmaleistung (kW) 1,5 Strahldurchmesser (d in mm) 3,0 Abstand (a im mm) 5,0 Vorschubgeschwindigkeit (v in mm/sek) 20 Gasdurchfluß (l/sek) 7 maximale Härte (HV) 900 Material saw steel B412, band length 6 m, tooth spacing 15 mm,
Width b of the cutting edge: 1.5 mm,
Untreated hardness 410 HV. Plasma power (kW) 1.5 Beam diameter (d in mm) 3.0 Distance (a in mm) 5.0 Feed speed (v in mm / sec) 20th Gas flow (l / sec) 7 maximum hardness (HV) 900

Beispiel 4: Härtung eines Stanzmessers für Leder und Textilien:Example 4: Hardening a punch knife for leather and textiles:

Material Bandstahl CK60 (Werkstoff-Nr. 1.1221)
Dicke: 2 mm
Härte in unbehandeltem Zustand: 300 HV (Vickers) Plasmaleistung (kW) 1 2 4 Strahldurchmesser (d in mm) 4 4 4 Abstand (a in mm) 4 6 8 Winkel zwischen Plasmaachse und Achse der Schneidkante (Grad) 0 0 0 Vorschubgeschwindigkeit (v in mm/sek) 25 35 50 Gasdurchfluß (l/min) 5 5 5 maximale Härte (HV) 860 890 940 Material steel strip CK60 (material no.1.1221)
Thickness: 2 mm
Untreated hardness: 300 HV (Vickers) Plasma power (kW) 1 2nd 4th Beam diameter (d in mm) 4th 4th 4th Distance (a in mm) 4th 6 8th Angle between the plasma axis and the cutting edge axis (degrees) 0 0 0 Feed speed (v in mm / sec) 25th 35 50 Gas flow (l / min) 5 5 5 maximum hardness (HV) 860 890 940

Beispiel 5: Härtung eines Hobelmessers für die HolzbearbeitungExample 5: Hardening a planer knife for woodworking

Material: 80 CrV 2 (Werkstoff-Nr. 1.2235)
Dicke: 8 mm
Härte in unbehandeltem Zustand: 280 HV (Vickers) Plasmaleistung (kW) 2 3 5 Strahldurchmesser (d in mm) 4 4 4 Abstand (a in mm) 4 6 8 Winkel zwischen Plasmaachse und Achse der Scheidkante (Grad) 60 90 120 Vorschubgeschwindigkeit (v in mm/sek) 20 30 40 Gasdurchfluß (l/min) 5 5 6 maximale Härte (HV) 840 880 905 Material: 80 CrV 2 (material no.1.2235)
Thickness: 8 mm
Untreated hardness: 280 HV (Vickers) Plasma power (kW) 2nd 3rd 5 Beam diameter (d in mm) 4th 4th 4th Distance (a in mm) 4th 6 8th Angle between plasma axis and cutting edge axis (degrees) 60 90 120 Feed speed (v in mm / sec) 20th 30th 40 Gas flow (l / min) 5 5 6 maximum hardness (HV) 840 880 905

Claims (14)

  1. A method for hardening the cutting edges of saws, knives and punching tools, primarily for processing wood, paper, cardboard, plastics, leather and textiles, by means of an energy jet which is guided over the zones of the tool to be hardened, characterized in that a plasma jet is used as energy jet, whereby the plasma jet (2) is guided at a relative speed (v) with respect to the cutting edge of the tool of 5 to 100 mm per second and the distance of the outlet nozzle of the plasma torch (1) from the cutting edge is up to 14 mm and furthermore the output of the plasma jet is between 1 and 10 kW and the diameter (d) is 3 to 7 mm at the outlet nozzle of the plasma torch (1).
  2. A method as claimed in claim 1, characterized in that the output of the plasma jet is between 1 and 5 kW.
  3. A method as claimed in one of the claims 1 or 2, characterized in that the diameter of the plasma jet (2) at the outlet nozzle of the plasma torch is between 4 and 6 mm.
  4. A method as claimed in one of the claims 1 to 3, characterized in that the distance (a) of the outlet nozzle of the plasma torch (1) is 3 to 10 mm from the cutting edge.
  5. A method as claimed in one of the claims 1 to 4, characterized in that the relative speed (v) of the plasma jet (2) is 15 to 50 mm per second with respect to the cutting edge.
  6. A method as claimed in one of the claims 1 to 5, characterized in that the plasma jet (2) is guided over the flanks of the teeth (7) in the zone of the upper cutting edge by mechanical movement of the plasma jet (1) transversal to the saw blade (3).
  7. A method as claimed in claim 6, characterized in that the saw stands still during the transversal movement of the plasma jet and that thereafter the saw is further advanced by one division of tooth, whereupon the next transversal movement of the plasma jet hardens the following tip of tooth (5).
  8. A method as claimed in claim 1 to 5, characterized in that the plasma jet is aligned to the centre of the tip of the tooth during the hardening of saws and that the saw blade carries out a continuous or stepwise movement in the direction of the teeth.
  9. A method as claimed in claim 8, characterized in that the plasma jet works in impulse operation, with an impulse frequency f of f = advance speed of saw blade divided by tooth distance, with the impulse duration being in the range of 0.2 to 0.8 seconds.
  10. A method as claimed in one of the claims 1 to 6 and 9, characterized in that the saw blade (3) carries out a continuous advance in the direction of the teeth, whereas the plasma jet (2) carries out a transversal movement with a frequency between 10 and 200 Hertz, caused by an electromagnetic deflection in the zone between cathode tip and lower edge of nozzle of plasma torch.
  11. A method as claimed in one of the claims 1 to 5, characterized in that the axis of the plasma jet coincides with the axis of symmetry of the cutting edge of a knife.
  12. A method as claimed in one of the claims 1 to 5, characterized in that the axis of the plasma jet with the axis of symmetry of the cutting edge of a knife encloses an angle α, which corresponds approximately to half the cutting angle β.
  13. A method as claimed in one of the claims 1 to 5, characterized in that the axis of the plasma jet encloses an angle α of approx. 90° with the axis of symmetry of the cutting edge of a knife.
  14. A method as claimed in one of the claims 1 to 5, characterized in that the axis of the plasma jet encloses an angle α of approx. 135° with the axis of symmetry of the cutting edge.
EP90910482A 1989-07-25 1990-07-18 Process for hardening the cutting edges of saws, knives and cutting tools Expired - Lifetime EP0483182B1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
AT179689A AT392483B (en) 1989-07-25 1989-07-25 METHOD FOR HARDENING THE CUTTING EDGES OF SAWS
AT1796/89 1989-07-25
AT2451/89 1989-10-24
AT245189A AT392981B (en) 1989-10-24 1989-10-24 Method of hardening the cutting edges of knives
PCT/AT1990/000071 WO1991001386A1 (en) 1989-07-25 1990-07-18 Process for hardening the cutting edges of saws, knives and cutting tools

Publications (2)

Publication Number Publication Date
EP0483182A1 EP0483182A1 (en) 1992-05-06
EP0483182B1 true EP0483182B1 (en) 1994-12-14

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EP90910482A Expired - Lifetime EP0483182B1 (en) 1989-07-25 1990-07-18 Process for hardening the cutting edges of saws, knives and cutting tools

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EP (1) EP0483182B1 (en)
CN (1) CN1027907C (en)
AT (1) ATE115639T1 (en)
AU (1) AU5960690A (en)
CA (1) CA2064032A1 (en)
CS (1) CS367490A3 (en)
DE (1) DE59008039D1 (en)
FI (1) FI95048C (en)
PL (1) PL286149A1 (en)
SK (1) SK279015B6 (en)
WO (1) WO1991001386A1 (en)
YU (1) YU135290A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4126910C1 (en) * 1991-08-14 1992-09-24 Georg Weiss Gmbh, 8201 Schechen, De
US5417132A (en) 1993-01-19 1995-05-23 Alan R. Pfaff Rotary cutting dies
DE4328961C2 (en) * 1993-08-27 1995-11-30 Fraunhofer Ges Forschung Process for the production of paper knives
AT404798B (en) * 1994-01-17 1999-02-25 Fischer Gmbh METHOD FOR HARDENING STEEL RUNNERS FOR SKI AND PLASMA HEAD FOR HARDENING EDGES IN STEEL MATERIALS AND DEVICE FOR HARDENING EDGES IN STEEL MATERIALS
DE4433720A1 (en) * 1994-09-21 1996-03-28 Linde Ag Method and device for hardening ski steel edges
AT403805B (en) * 1994-12-23 1998-05-25 Fischer Gmbh METHOD FOR MACHINING STEEL EDGES FOR SKI OR THE LIKE
EP0780199B1 (en) * 1995-12-19 2002-03-27 Katayama Steel Rule Die, Inc. Method of producing a counter plate
US6189414B1 (en) 1995-12-19 2001-02-20 Yoshizawa Industry Inc. Counter plate and cutting die for die cutting machine
ATE210533T1 (en) * 1996-02-15 2001-12-15 Bernal International Inc PUNCHING KNIFE AND MANUFACTURING PROCESS
NL1040070C2 (en) * 2013-02-27 2014-08-28 Hho Heating Systems B V PLASMATRON AND HEATING DEVICES INCLUDING A PLASMATRON.
CN110066994A (en) * 2018-01-23 2019-07-30 武汉苏泊尔炊具有限公司 The processing method of cutter and the cutter
TW202001977A (en) * 2018-06-08 2020-01-01 財團法人工業技術研究院 Plasma system for substrate edge treatment and treatment method using the plasma system
CN108866303B (en) * 2018-08-02 2024-02-27 泉州市海恩德机电科技发展有限公司 Quick pushing up-down oil injection mechanism for large-diameter saw blade iron matrix

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JPS52115711A (en) * 1975-05-26 1977-09-28 Toushichi Ishizawa Method of hardening saw teeth
GB2172821B (en) * 1984-05-08 1987-12-23 Ki Proizv Ob Polimer Mash Method of making hollow cylindrical articles

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FI920328A0 (en) 1992-01-24
EP0483182A1 (en) 1992-05-06
DE59008039D1 (en) 1995-01-26
FI95048C (en) 1995-12-11
SK279015B6 (en) 1998-05-06
CN1049030A (en) 1991-02-06
CA2064032A1 (en) 1991-01-26
FI95048B (en) 1995-08-31
CS367490A3 (en) 1992-01-15
CN1027907C (en) 1995-03-15
WO1991001386A1 (en) 1991-02-07
AU5960690A (en) 1991-02-22
PL286149A1 (en) 1991-03-11
ATE115639T1 (en) 1994-12-15
YU135290A (en) 1992-12-21

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