DE7503466U - CORROSION-RESISTANT CUTTING TOOL - Google Patents

Description

· Patent attorneys

Dipl.-Ing. Dipl.-Chem. Dipl.-Ing.

E. Prince - Dr. G. Hauser - G. Leiser

Ernsbergerstrasse

8 Munich 60

Our sign; E 822x May 29, 1978

G 75 03 A66.1

Dr Niels Nikolaj ENGEL ....

Corrosion-resistant cutting tool

The invention relates to a corrosion-resistant cutting tool, in particular a band saw blade Made of martensitic steel with a long service life, the cutting edge with a hard one Metal compound is coated.

Schw / Ba

7503466 07.12.78

So far, cutting tools, such as band saws

leaves, made of a martins! tischen steel, which has been subjected to a heat treatment in order to give it a hard cutting edge (cutting edge). One also has The cutting edges have already been coated with tungsten carbide, titanium carbide or other hard materials harden and thus extend their service life.

From US patent specification 3 003 370 it is already known to attach cutting tools to the particularly claimed Carburizing points and thus subjecting them to carbide hardening. From the US patent 3 832 219 is the use of a linear accelerator for the implantation of chromium ions or carbon ions into the surface of a metal in order to harden it. From U.S. Patent 2,422,561 it is also known to use the entire surface of a cutting tool, in particular a conventional steel saw blade to subject it to impulse hardening. However, this has the disadvantage that in this case the entire body of the saw blade is hardened and thereby the flexibility of the area, which is desirable in itself is reduced outside the cutting edges.

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The invention is based on the object of providing a cutting tool, In particular, a saw blade made of martensitic steel with a long service life, which is only to the particularly stressed areas is particularly hardened.

According to the invention, this object is achieved by a tool body with a cutting edge, a coating with embedded ions, which cover the surface of the cutting edge, and submicroscopic, pulse-hardened ones martensitic grains in this surface of the cutting edge in contact with the coating.

The cutting tool according to the invention is selectively hardened at the cutting edge to such an extent that that there is a particularly long service life, the martensitic steel body of the cutting tool retains its desired flexibility outside of the cutting edge. The cutting tool according to the invention also has an unusually high corrosion resistance »which is a multiple of. Corrosion resistance one after known] ?. Process manufactured cutting tool amounts.

The cutting tool according to the invention is in particular a band saw blade that is cut to the desired length is cut to size and welded together at the ends.

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The invention will now be explained by way of example with reference to the drawing. Show it:

Fig. 1 is a side view of part of an inventive Cutting tool,

2 is an enlarged side view of a tooth of the in Fig. 1 shown cutting tool,

3 is a schematic view of an ion implantation vacuum chamber, which are used, for example, for the production of the cutting tool according to the invention can be,

4 shows a side view of part of a cutting tool when passing through an impulse hardening device and

FIG. 5 is a plan view of the arrangement of FIG.

In the drawing, the cutting tool is shown as a band saw blade 10, which has a uniform width over its length, the teeth 12 of the band saw blade 10 being best seen in FIGS. The outline shape of the saw blade 10 is conventional, and comprises a straight rear edge 11 and a plurality of successive, in the; same distance spaced teeth 12 along its leading edge _s

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Each tooth 12 has a front (rising) edge (cutting edge) 13 and a rear (sloping) edge 14 euf, which is taper outwards to a point 15. The teeth 12 are alternately laterally opposite one another in opposite directions offset. The leading edge or cutting edge 13 is sharpened in a conventional manner. The saw blade 10 consists of a martensitic one Steel with 0.95 to 1.05% carbon, which has a hardness of about 70 on the Rockwell 30N scale (this corresponds to a value of about 50 on the Rockwell C scale). Each tooth 12 has a coating 16 covering its tip and made of a hard metal, for example a refractory metal compound, e.g. B. tungsten carbide or titanium carbide. The coating 16 is about 0.0254 mm di de and covers about 1 mm in an L-shape along the tip area of the saw blade 10, wöbe: it extends about 1.52 mm to about 1.78 mm away from the tip 15 inwardly along the cutting edge 13. The cover 16 extends about 1.76 mm to about 12.7 mm along the rear edge 14.

In the manufacture of the saw blade, a steel collar is stamped in order to produce the successive teeth 12. The teeth 12 are then successively out of the plane of the flat body 18 bent out, wherein each tooth 12 is bent out in a lateral direction opposite to the adjacent tooth 12. the Cutting edges 13 of teeth 12 are then sharpened.

According to the invention, a piece of the saw blade 10 produced in this way, which is generally about 150 to about 180 m long, is wound up for producing the saw blade collar 20 shown in FIG. 3. The collar 20 is cleaned beforehand in the normal manner

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and then placed with the teeth up on a cathode plate 21 in a vacuum chamber 22. The collar comes with the plate 21 firmly electrically connected. The chamber 22 is equipped with a tungsten anode thread 23 above the plate 21 and the Filament 23 is of the ion implant material, for example a piece of tungsten or titanium wire 24, covered. The electrical conductors 26 and 27 connect the anode thread 23 and the cathode plate 21 having a direct current potential E. A vacuum pump P is provided to evacuate the chamber 22 and the gas lines 28 and 29 serve to selectively introduce the inert purge gas (argon) and the carburizing gas (Methane) into the chamber 22. Each line has a control valve V on. The chamber 22 is then pumped down to one Vacuum of 2 χ 10 Torr or better evacuated with frequent flushing with argon gas. Such a low pressure is required to remove the absorbed gases generated therein. After that, the argon gas is introduced into the chamber up to one point

-2 plasma sustaining pressure of about 10 torr. Then it will be a DC electric voltage is applied to the anode filament 23 and the cathode plate 21 and it is gradually increased until forms a pink argon plasma. Argon is used in chamber 22 because it can harden martensite and is heavy, so that it increases the impact force of the ions on the cathode, which results in a better cleaning effect. The plasma formation starts within the range of 1 kV and 50 mA and can then be sustained at a much lower potential will. The potential setting can according to the needs can be varied, it is generally 2 to 3 kV.

The collar 20, implanted in the cutting edge of metal ions

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is first carried out with the argon plasma through the ions cleaned. The argon injects any atomic impurities or any dirt that is present on the exposed surfaces, particularly the teeth 12. A Part of the argon penetrates the steel and causes the formation of superfine martensite, which is used in the subsequent impulse hardening arises. The ion implant material on a thread (e.g. a wire 24) or from a bath of a molten one Metal that is heated by an electron gun,

forms the anode within the chamber. By passing sufficient current through filament 23 while maintaining of the argon plasma, the thread 23 and the wire 24 are gradually heated until the wire 24 melts on the anode and then, under-

supported by the considerable vacuum inside the chamber, evaporates. These ionized particles are held by a collar 20

j of the cathode plate 23 due to the large potential difference (the

'\ can vary from 500 to 50,000 V) and is thereby attracted

causes ion implantation. In fact, the first - ions to hit the surface of the collar 20 will be in the ι Tough 12 implanted (embedded) and lead to a gradual

Ί borrowed transition between the metal of the teeth 12 and the surface. When the surface is saturated by the ion implantation ¹¹

; the rest of the ions will be on the surface of teeth 12

deposited over the stored ions. The depth of penetration of the

j ions implanted in the substrate depends on the hardness of the substrate away. When the implanted metal ions, e.g. B. titanium or; Vanadium ions, with the carbon present in the steel sheet substrate

; react to fuel, it is still not known whether they

form a precipitate or be "in solution" half of the crystal lattice of the substrate. This is due to the fact that the connections formed by the implanted ions to kleii

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are to be detected by today's methods too be able. The duration of the ion implantation can be fractions of a few can be varied from seconds to several minutes. During the ion implantation process, the vacuum in the chamber decreases approximately However, it should be kept at the correct value by adjusting the argon pressure or metal evaporation.

The ion implantation described above can be performed in a Range of steels or alloys containing iron, such as B. razor blades, technical blades, band saws, files, nails And the like., As well as other metals and moldings, such as. B. meat chopping machine plates. Recommendable are martensitic steels. Such a martensitic one Steel is used for the body of the saw blade 10.

Although titanium or tungsten are the most suitable implantation metal Seems to be, can also be different if desired other elements are implanted (stored) in the surface in the form of ions. This includes all elements that are difficult to melt, such as scandium, titanium, yttrium, zirconium, hafnium, vanadium, Niobium, tantalum, chromium, molybdenum and tungsten, the rare earth elements such as lanthanum, cerium, praseodymium, neodymium, promethium, Samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium, the elements of the actinide series, such as Actinium, Thorium, Protactinium, Uranium, Neptunium, Plutonium, Americum, Curium, Berkelium, Californium, Einsteinium, Fermium, Mendelevium, Nobelium and Lawrencium, as well as iron, cobalt Nickel and boron. Some of these metals require the use of a high energy evaporation unit, such as an electron gun, to vaporize them. Electron beam evaporation is preferred in industrial production.

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With super hard materials that are implanted on the substrate surface Ions can be added, wear-resistant and corrosion-resistant cutting edges can be produced. The hardest known materials are the carbides, borides and nitrides, which are compounds of elements the transition series with elements of the second period, such as. z.

B. TiC, ScN, VC, Cr.C_ and TiB. In addition, the Oberj ''43

surface of the teeth with the implanted ions any other Metal within the list of ion implantation materials given above can be added. These materials can be added to the steel substrate of the teeth in the form of compounds, however, these are very stable and difficult to vaporize. The best practice is for ion implantation to use the pure metal (Ti, Cr, B, Sc and the like) in the cutting edge and then the metal in the respective carbide, boride or to convert nitride. Whether carbon, boron or nitrogen is used depends on the substrate coating. So is for example Carbon is the best material for conversion with titanium, boron is the best material for conversion with vanadium and nitrogen is the best material to react with scandium.

The carburizing, boridizing or nitriding must be carried out in an oxygen-free atmosphere because otherwise an oxide of the metal coating could form on the substrate which would be more brittle than the carbide, boride or nitride thereof Metal. The carburization can be done in several ways: a carbon containing gas, e.g. B. a hydrocarbon, can with the ion-implanted collar 20 to a temperature within the range of 600 to 900 C (usually above 800 ° C) so that the carbon and the implanted

7503466 07.12.78

th metal ions react with one another to form a carbide ^; z. Of TiC, and the like. Suitable carbonation gases include methane, natural gas, propane, acetylene and gasoline. The cutting teeth can be carburierjt also in any other suitable manner, for example by any conventional crate, \ cyanide or Gascarburierungsverfahren. You can also use a | plasma formed by a nitrogen / propane mixture (or any other carburizing gas mixture containing ^{>: carbon vaporized from an arc).}

After the implantation metal. (Titanium or tungsten) to about

3
1 mm of the tooth tip surface of teeth 12 has been deposited to a thickness of about 0.0254 mm, the ion implantation ^! preferably interrupted and the titanium or tungsten forming the coating is converted into a carbide. This is achieved by introducing a mixture of methane, hydrogen and argon or propane, hydrogen and argon into the chamber 22 immediately after the ion implantation has ended. The hydrogen brew;] to be introduced only in an amount sufficient to ensure a t reducing atmosphere. Then the collar 20 of the saw blade 10 is allowed to cool and removed from the vacuum chamber 20. Each tooth 12 has a coating 16 of titanium carbide or tungsten carbide I bid extending along its cutting edge

13 from a position between the tip 15 and the curvature * (Notch) of the saw tooth 17 extends to the tip itself, and it extends from the tip 15 along the rear edge

14 and ends in a position between the tip 15 and the Ein4 Curve 17. This is shown in FIG. As stated above- [ give the length of the coating 16 along the cutting edge; 13 about 1.52 to about 1.78 mm, while the length along the back | direct edge 14 is about 1.78 to about 3.81 mm. The coating; '■

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16 overlaps the side surfaces on both sides of the cutting edge 13 and the rear edge 14. However, the overlap on the sides is now only about 0.0254 to about 0.0762 wide.

An important step in the process of the invention is that Impulse hardening of the coated teeth 12, which takes place after the collar 20 of the saw blade 10 has cooled and air has been let into the chambers 22. The federal government 20 is then from the Chamber 22 removed and traveled linearly at a rate of about 10 to about 12 teeth per second fed along. On this route the teeth 12 are successively exposed to the high-frequency magnetic flux of the throttle (coil) 31 subjected to an impulse hardening device known per se, indicated generally by the numeral 30. Such Impulse curing apparatus device 30 is also in U.S. Patent 2 799 760. The device 30 is equipped with a coil or choke 31, which is made in one piece of a heavy electrical wire is shaped to have a pair of webs 32 (which are electrically connected to device 30 are connected), each leading to an upper loop 33 and a lower loop 34. Loops 33 and 34 are in parallel planes at a distance from each other concentrically arranged on a vertical axis. Loops 33 and 34 include each about 360, the ends of the loops 33 and 34 being connected to one another by an intermediate part 35.

The saw blade 10 is guided along a path in such a way that the tip 15 of each tooth 12 of the axle passes through the loops 33 and 34, which is also located between them, is fed and temporarily arranged on this. The loops 33 and

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34 should also be of a diameter large enough that at least the outer half of each tooth 12 extends temporarily located within the inner diameter of loops 33 and 34, as shown in FIG. The device 30 is arranged to emit pulses of 20 MHz or more and it operates at about 6000 volts, whereby induction heating lasting from about 9 to about 10 milliseconds is achieved. This creates pulsating

Square waves of more than 10 kilowatts per cm for induction impulse hardening. Normally a pre-hardened steel only needs a single pulse per tooth. A non-pre-hardened one Steel is hardened by the first pulse and then given its fine-grain structure by the second pulse.

The high-frequency magnetic field of the choke 31 surprisingly causes a structural change in both the carbon-implanted titanium as well as the underlying steel of tooth 12. If a pulse of short duration (1 to 20 milliseconds) acts, only a relatively thin steel layer with a thickness of about 0.1 to about 0.2 mm is heated. This area will heated to a temperature within the austenitizing range, namely to a temperature of about 1000 to about 1200 C. and the heated area is immediately deepened by the heat conduction of the large, non-heated area of the saw blade Temperature suddenly cooled. This way it becomes a martensitic Fine structure formed with fine grains that are so fine that their structure cannot be seen by optical microscopes more can be resolved. This clasps and holds the titanium carbide layer, which is becoming saturated, and through ion implantation they are embedded deeply in the steel. the

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The hardness of the coating 16 is also improved, although it is non-magnetic.

Such a procedure results in teeth with a martensitic one Section that has a hardness of 1000 to 1350 HV and in some cases greater than 1400 HV on the Vickers scale having. The coating (titanium carbide) has a hardness of 3000 to 4000 HV on the Vickers scale. Using Even under corrosive conditions, for example for cutting up meat and bones, a hold according to the invention The manufactured saw blade is at least 8 to 10 times as long as a conventional saw blade. The final stage of manufacture A band saw blade consists of cutting the saw blade to a certain length and cutting the ends together to be welded to produce a continuous loop,

7513466 12/07/78

Claims (3)

Dlpl.-lng, Dlpl.-Chem, Dlpl.-lng, E. Prinz - Dr. G. Hauser - G. Leiser Ernsberoerstrasae 19 8 Munich 60 Our reference; E 822x May 29, 1978 Dr Niels NikolaJ ENGEL ... protection claims 1. Corrosion-resistant cutting tool, in particular band saw blade made of martensitic steel with a long service life, the cutting edge of which is coated with a hard metal compound, characterized by a tool body with a cutting edge, a coating with embedded ions that covers the surface of the cutting edge, and submicroscopic, impulse-hardened martensitic grains In this surface of the cutting edge in contact with the coating. 2. Cutting tool according to claim 1, characterized in that the coating made of tungsten carbide and / or titanium carbide consists. 3. Cutting tool according to claim 1 or 2, characterized in that that the tool body has a Wickers hardness of more than 1000 HW, while the coating has a Has a Wickers hardness of more than 3000 HW. Schw / Ba 7503466 07.12.78 ti Cutting tool according to one of the preceding claims, characterized in that several at a distance from one another arranged teeth are provided, the tip of which the cutting edge is each adjacent, wherein the coating extends over the back and front edges of each tooth. Cutting tool according to Claim 4, characterized in that the coating extends from a point in the middle between the notch between two teeth and the tip of each tooth to the actual tip both lengthways the cutting edge as well as along the trailing edge of each tooth 7503466 07.12.78