The method of hardening tool

 

(57) Abstract:

The invention relates to the technology of surface hardening a metal tool and can be applied in engineering. An object of the invention is to increase the tool life. The technical result is achieved by the method of hardening includes applying a wear resistant coating and pulsed high-energy impacts on the surface of the tool before and after coating. High-energy impact combines gas-dynamic processing surface of the tool facing the plasma containing alloying elements, passing through the surface layer and the coating layer of the electric current and the heat from the working surface. This significantly increases the efficiency of the coating on the profile rolling tool. 5 C.p. f-crystals, 3 tables.

The invention relates to a method of hardening a metal tool and can be applied in engineering.

A method of obtaining composite electrochemical coatings based on chromium, which is the electrochemical deposition of the electrolyte plating containing suspended colombieres optimal current density (application No. 92002681, IPC 6 C 25 D 15/00, publ. 19.06.1995).

This method is designed to improve the wear resistance of the surface of tools and machine parts. Technology is carried out without deformation, warpage of the product and not prone to cracking.

The disadvantage of this method of hardening tool is the low productivity of the deposition, due to the galvanic process, and, most importantly, the inheritance of all surface defects, which are formed by grinding and surface preparation for plating. In addition, the process of the galvanic coating leads to a negative voltage on the surface of the product that is summed with a negative voltage after grinding. The result is applied to the surface layer with high wear and EP properties, but the profile rolling tool works with alternating high contact loads. The implementation of this method adversely affects the strength characteristics of the profile rolling tool.

Also known is a method of thermal processing of products is highly concentrated sources of energy and.with. No. 1482208, IPC 6 C 21 D 1/09, publ. 27.03.1996, which can be poverhnosti tool and reduce processing time hardening the surface of the rollers provide a pulsed electron beam with variable thickness. The upper limit ripple (maximum power) provides heating of the surface layer to a depth of 0.5-0.6 mm to the quenching temperature (1200-1300). The lower limit ripple choose from a calculation of the temperature of the treated surface temperature tempering (450-500). The transfer speed of the workpiece 8 m/h, pulse frequency of 3 Hz, the overlap factor locally treated plots of 0.5-0.6. The surface after processing has a hardness of 60-65 HRC, has no cracks and other defects.

The method of thermal treatment of products with highly concentrated energy sources allows you to create a sufficiently thick hardened layer on the surface of the rolling die, but this layer has a lower anti-friction properties in comparison with a layer of chromium with a diamond hardening phase.

The closest in technical essence of the present invention is a method of surface hardening a metal tool, patent No. 2101382, IPC 6 23 8/36, publ. 10.01.1998. In this way the increased resistance of the cutting tool is provided by the increasing diffusion of the galvanic coating to the substrate and reduce the stresses on its surface. Complex application of sposobnoe, which is to process the surface of the cutting tool in the field of positive corona discharge, the coating of the nitrides of refractory metals and final processing of cutting tools in a magnetic pulse field. This method significantly increases the efficiency of the tool.

A disadvantage of this known method prototype is the fragility and low efficiency of the layer of nitrides, due to their detachment at high contact loads. The field of positive corona discharge cleans the surface of the tool, but practically does not reduce negative stress and does not form a hardened layer before coating. In addition, post-processing tool in a pulsed magnetic field reduces stress in the nitride layer and the surface layer of the tool, but does not affect the density and strength of adhesion of the layer of nitride based.

The present invention is to increase tool life, improve its quality through the reduction of the level of negative voltage on the surface of the tool, create a hardened surface layer before coating, subsequent compaction and primechanie nonene tool including the application of wear-resistant coatings, high-energy impacts on the surface of the tool perform pulse before and after coating, combining the gas-dynamic surface treatment tool pulsed plasma jets containing alloying elements, passing through the surface layer and the coating layer of the electric current with subsequent periodic removal of heat from the surface of the tool.

With gas-dynamic surface treatment tool pulsed jet of plasma prior to coating combined with the influence of nitrogen ions and heavy metal ions, and after coating the gas-dynamic machining surface of the tool combined with the influence of ions on the surface predominantly of carbon and heavy metal ions.

In addition, the density of electric current is reduced from 3... 4 kA/cm2on top of profile rolling tool to zero in the hollows of the profile.

Complex machining surface of the tool is provided by 5-th and 10-th high-energy pulses of plasma and electric current, and the surface of the tool fanned cooling gas or air.

In the proposed the pulsed electric current density of 2000... 8000 A/cm2.

Saturating elements metals and orbitastarmedia particles produced from fine powders, which is served in a high-energy jet of plasma or saturating elements, and orbitastarmedia particles produced by overheating of the end of the compact electrode by electric discharge. Gaseous elements for a synthesis injected in a pulsed plasma jet in the form of hydrocarbon and nitrogen gases. To enter carbides used compact electrode, which consists of an alloy based on tungsten carbide.

In the processing method of the tool are such features as passing through the coating layer of the electric current and the simultaneous effects of pulsed magnetic field and the elastic-plastic deformation. These symptoms can significantly intensify the diffusion processes primechanie coverage. So the coefficients of mass transfer in solid metal with pulsed magnetic influence or elastic-plastic deformation at two orders of magnitude larger than thermal diffusion coefficients. The influence of several kinds of pulse exposure leads to a significant acceleration of mass transfer, and this increase is needit the impact namely, shock, electromagnetic, thermal. Each of them plays the role of initiator diffusion processes that seals the floor and ensures its diffusion primechanie. In the result of the interaction of factors is accelerated mass transfer of alloying elements from the coating into the depths of the metal surface of the tool.

For periodic cooling doped layer apply the blowing of the working surface of the tool after each pulse saturation cooling gas mainly composed of air or nitrogen. This determines the pendulum mode thermal Cycling of the surface layer, which also intensifies the mass transfer of alloying elements.

Such essential features as processing plasmas, and electric current of the working surfaces of the rolling tool before coating, is formed on the surface reinforced solid layer with compressive stress. Application of composite coatings (chrome+diamonds) on hardened tool layer and subsequent sintering of the coating pulsed plasma and electric current leads to compaction of the chrome layer and the diamond grains diffusion primechanie chrome hardened to what enables you to improve the lubricating properties of the chrome coating and to increase the adhesion of the diamond grains and a layer of chromium.

In the method of obtaining the saturating elements, metals and turbidostatic particles is made from fine powders and due to the overheating of the end of the compact electrode. By means of electric discharge due to the ability to accurately metering the flow of material and putting it into a jet of high-energy plasma. The use of compact electrodes, which consist of an alloy based on tungsten carbide and hydrocarbon and nitrogen gases, provides input into the surface of the tool carbides and nitrides of refractory metals.

Synthesis and deposition of alloying elements and compounds directly on the hardened surface of the tool through the submission of these elements with high speed perpendicular to the surface and passing through it an electric current leads to the formation of a new technical effect when processing tool - directional movement required for the synthesis of elements in one pulse cycle.

According to the invention by way of the processing tool is widely used surface treatment beams of high energy density. It is known that in the process of high-energy impacts are fast heating (time of nagrereply as in metal volume and in the environment. High speed heating and cooling of the metal surface layer (104...108K/s) contributes to the formation of a dispersed structure with high dislocation density and concentration of alloying elements.

Thermal effect combined with the processes of alloying the surface of the tool by melting pre-applied galvanic coatings and processing of plasma, which contains alloying elements: nitrogen, carbon, and metals. The effectiveness of pulsed exposure on the surface of the product due to the higher speeds of heating and cooling, elastic-plastic deformation of the surface and, as a consequence, the intensification of almost all known mechanisms of diffusion.

Pulsed-plasma technology strengthening processing tool prior to coating includes the following methods impact: elastic-plastic deformation, the effects of sound and pulsed magnetic field, thermal and electro-processing and deformation of metals and alloys in the process is reversible ( ) changes.

The method of hardening tool in the following order. The surface of the tool, apriopriate providerpatient interaction with a shock wave and pulsed plasma jets, then the surface is exposed to an electric current. The amplitude of the current to 8 kA. The result is a pulsed magnetic field up to 2000 E. further, for 3... 5 MS, on the surface natcat products of combustion and erosion of the electrodes, which contain alloying elements.

In the pulsed-plasma treatment on the surface of the tool is formed microcrystalline doped layer. The composition of this layer depends on the amount of alloying elements in the plasma and the number of pulses processing. The hardened layer has a greater thickness and uniformity after repeated (>5 imp.) pulsed-plasma treatment.

The highest hardness of the hardened layer was achieved using electrodes made of tungsten carbide (samples are HM held quenching + tempering).

Processing is carried out without melting the surface of the rolling die, the power density of the jet was 106W/cm2. X-ray phase analysis of the layers, hardened pulsed plasma, captures the broadening of the lines-Fe and the appearance of lines residual AU-stanica Fe. Increasing the number of pulses results in further broadening of the lines-Fe while reducing their intensite processing greatest in the case of using the electrode made of tungsten carbides. X-ray study showed that the material of the consumable electrode penetrates the hardened layer of the product. For example, when using a consumable electrode made of tungsten carbides he found in the hardened layer at a depth of 20 μm.

Before processing the pulsed plasma instrument passed standard mechanical, thermal and abrasive. Pulsed plasma treatment was used as a preparatory operation before coating. Hardening was subjected to only the profile rolling tool.

Processing modes were selected with a minimum power density sufficient to heat the peaks of the profile tool to melting. Such a mode was provided by alloying the molten surface elements constituting the plasma jet. When surfacing used consumable electrode made of molybdenum, chromium or tungsten carbide, plasma-forming gas contains an excess of propane. Processing was carried out with multiple pulsed plasma hardened surface.

Then, after hardening, on the working surface of the tool electroplating method was applied composite electrochimica the electrolyte plating additive is introduced product UDA, produced by THE 84-1124-87 containing 3-10 wt.% parts of the basic substance in the form of an aqueous suspension. The latter is due to the necessity of preserving the superfine additive, which when dried forms aggregates up to several microns.

Used self-regulating electrolyte plating. SGAs3(chromic anhydride) 250±25 g/l TO2SiF3(potassium silicofluoride) 18±20 g/L. BaSO4(barium sulfate) 5±6 g/L. H2SO4(sulfuric acid) of 0.25±0.75 g/l Product UDA - 10±15 g/l Suspension product UDA takes 1/3 1/4... part of the total volume of the electrolyte. Mode selection: current density, temperature, deposition time - specifically for each type of rolling tool.

The maximum hardness while maintaining the high quality obtained at a temperature of 56 C and a current density of 50... 70 A/DM2. At the time the coating up to 5 min, the rate of formation of kets higher than chromium, on average 1.5 times.

After electroplating coating products are processed using a pulsed plasma source. A jet of plasma is directed onto the working surface. In the plasma jet is injected carbon, nitrogen and metal elements involved in the synthesis of carbides and carbonitrides. Luigirules and tools. When the electric circuit for the plasma jet to the surface electric current flows. The plasma stream contains metal, nitrogen, and carbon, necessary for synthesis. In the plasma jet are also elements such as molybdenum and tungsten, zirconium and hafnium, which are high speed (3... 8 km/s) bombard harden the surface. Alloying metals interact with the active components of the galvanic layer of chromium, the products of plasma-chemical synthesis condense on the chromium layer. Synthesis and deposition of solid anti-friction compounds on the composite layer of chromium+diamond high performance tool. Electrical current transmission contributes directed current of electrons, ions and atoms in the coating and diffusion mechanism fixing the chrome layer on the substrate.

For approbation of the method of inoculation pulsed plasma plasma jet formed the combined explosion of pre-compressed combustible gas mixture and an electric discharge through the combustion products, which ensured a high temperature 20000... K and speed up to 8 km/s in the plasma jet. As components of the combustible gas mixture used propane-butane+Ki is STRADOM and the surface of the tool.

Electric current from the electrode-anode goes to the surface of the product. When this electric current activates the synthesis of solid compounds, heating the surface and diffusion. The activation process is when the density of electric current to 8000 A/cm2. A large current density leads to overheating of the surface, melting and its destruction.

Comparative tests of the rolling tool after galvanic chrome plating with the use of composite coatings (KP) and hardening of the proposed method showed that the efficiency of it is increased in 4 times.

Example 1.

Was carried out pulse processing profile rolling dies before the deposition of the composite electroplating. As an alloying element used molybdenum. Processing was carried out by 3, 5 and 10 pulses. Then put the electroplating method of the composite coating.

Industrial tests have shown that the efficiency of the die increased to 190 tons was Observed brittle fracture of the coating, due to the weak adhesion with the substrate (see table 1, items 1... 3).

Example 2.

Was carried out pulse processing profile rolling dice to osajda is carried out 3, 5 and 10 pulses. Then put the electroplating method of the composite coating.

Industrial tests have shown that the efficiency of the die increased to 220 so the Optimal number of pulses 5. Further increase in the number of pulses of the health coverage is not increased. After 220 tonnes of rolled products was observed brittle fracture of the coating. A small increase in resistance of the coating due to the higher adhesion of the galvanic coating to the substrate, chrome pulsed plasma (see table 1, POS. 4, 5, 6).

Example 3.

Was carried out pulse processing profile rolling dice before and after deposition of the composite electroplating. As an alloying element used chrome. Processing was carried out 3, 5, 7 and 10 pulses. Then put the electroplating method of the composite coating.

Industrial tests have shown that the efficiency of the die increased to 340 so the Optimal number of pulses 7. Further increase in the number of pulses of the health coverage is not increased. After 320 340... t of rolled products was observed in the wear surface of the composite coating. Improved resistance dice movement by the action of a plasma pulse (see table 1, items 7, 8, 9 and 10).

Example 4.

Was carried out pulse processing profile rolling dice before and after deposition of the composite electroplating. As an alloying element used tungsten. Processing was carried out 7 and 10 pulses. Then put the electroplating method of the composite coating.

Industrial tests have shown that the efficiency of the die increased to 380 t 7 pulse processing and decreased to 340 tons at 10 pulses processing. The optimal number of pulses 7. Further increase in the number of pulses lowered the performance of the coating. After 320 380... t of rolled products was observed in the wear surface of the composite coating. Increasing the resistance of the die due to the high energy ions of tungsten, which are more efficient at processing the surface of the KP, but with a large number of pulse plasma processing observed Preobrazhenie surface, which reduces the efficiency of the coating (see table 1, items 11, 12).

Example 5.

Was carried out pulse processing profile rolling dice before and after deposition of the composite electroplating. As alloying semenkovo current up to 2 kA/cm2on top of profile rolling tool to zero in the hollows of the profile.

Industrial tests have shown that the efficiency of the die was 300 so Further increase in the number of pulses of the health coverage is not increased. After 300 tonnes of rolled products was observed in the wear surface of the composite coating. Increasing the resistance of the die due to the high adhesion of the galvanic coating with the substrate, which is caused by primechanie it under the action of pulsed plasma (see table 2, item 1).

Example 6.

Was carried out pulse processing profile rolling dice before and after deposition of the composite electroplating. As an alloying element used chrome. Processing was carried out by 5 pulses. When processing was provided electric current density up to 4 kA/cm2on top of profile rolling tool to zero in the hollows of the profile.

Industrial tests have shown that the efficiency of the die was 340 so Further increase in the number of pulses of the health coverage is not increased. After 340 tonnes of rolled products was observed in the wear surface of the composite coating. The increase is on primechanie it under the action of pulsed plasma (see table 2, item 2).

Example 7.

Was carried out pulse processing profile rolling dice before and after deposition of the composite electroplating. As an alloying element used chrome. Processing was carried out by 5 pulses. When processing was provided electric current density up to 6 kA/cm2on top of profile rolling tool to zero in the hollows of the profile.

When hardening was observed melting peaks of the profile rolling dice. The rollers were not tested (see item 3 of table 2).

The results of industrial tests determined that the operability of the rolling tool increased to 340 so Further increase in the number of pulses of the health coverage is not increased. The increase in the density of electric current of more than 4 A/cm2leads to the melting peaks of the profile, which is unacceptable for a rolling tool.

Example 8.

Industrial tests have shown that the rollers only plated with CP without pulse treatment have efficiency up to 80 so After 80 tons of rolled products was observed brittle fracture profile under the floor, which is caused by the creation of negative on the item 1).

Analysis of test results showed that the instrument is processed by the proposed method had no failures due to brittle fracture of the working surface or brittle fracture of the coating. Cause of failure is the deterioration of the coating KP on the surface profile. Surface treatment tool pulsed plasma prior to coating creates a surface layer of compressive stresses and “heals” the defects generated during grinding.

Surface treatment tool pulsed plasma prior to coating and the coating increases the efficiency of the coating. The performance increase is also due to primechanie the hardened coating to the substrate, due to the energy pulse effect and the increase of the pulse energy due to the introduction of heavy element tungsten.

Commercial operation experience has shown that after the pulsed-plasma treatment before and after coating workability of the tool has increased in 4... 5 times.

The processing method allows to solve the contradiction between the high requirements of the working surfaces (high contact activities) and not less stringent requirements for durability. Primemeridian the method of hardening along with high performance and has such advantages as the ability to process automation. High-energy plasma jet cleans and heats the surface, “heals” the defects in the surface layer, forms a compressive stress, legeret surface. In addition, pulsed-plasma primechanie coating seals the floor and ensures its diffusion coupling.

The proposed method for the processing tool is a resource that due to the low consumption of alloying elements and electrical energy in combination with high performance up to 0.5 m2/hour. The method allows to process (heat) only working (cutting) surface, which solves the problem of improving the wear resistance without altering the structural state of the entire product.

1. The method of hardening tool, including the application of wear-resistant coatings and high-energy impacts on the surface of the tool, characterized in that the high-energy impacts on the surface of the tool perform pulse, before and after coating, combining the gas-dynamic processing surface of the tool facing the plasma containing alloying elements, and the transmission through the surface capabilities of the instrument.

2. The method according to p. 1, characterized in that the high-energy impacts on the surface of the tool produce 5 to 10 pulses.

3. The method according to p. 1, characterized in that the gas-dynamic machining surface of the tool facing the plasma prior to coating combined with the influence of nitrogen ions and heavy metal ions.

4. The method according to p. 1, characterized in that the gas-dynamic machining surface of the tool facing the plasma after coating combined with the influence of ions predominantly of carbon and heavy metal ions.

5. The method according to p. 1, characterized in that the electric current density is reduced from 3...4 kA/cm2on top of profile rolling tool to zero in the hollows of the profile.

6. The method according to p. 1, characterized in that after each pulse of high-energy surface treatment tool is blown by the cooling gas, mostly air.

 

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FIELD: mechanical engineering.

SUBSTANCE: the invention presents a method providing an increase of wear-resistance of the metal-cutting tools made out of tool steels by magnetic-pulse treatment with a preheating and an installation for its realization. The invention is dealt with the field of mechanical engineering, in particular with production of metal-cutting tools made out of tool steels by preheating and magnetic-pulse treatment. The technical result is increased wear-resistance of the metal-cutting tools made out of tool steels due to removal of internal stresses, increase of thermal conductivity, ordering of magnetic structure of a material. For achievement of the technical result conduct a preheating of the tools by high-frequency currents (HFC) with consequent action by a pulse of a magnetic field of high magnetic intensity. The method is realized by an installation containing a combined inductor with windings. At that a winding of the inductor, powered by high-frequency currents, is placed inside the winding powered by a magnetic-pulse device.

EFFECT: the invention allows to increase wear-resistance of the metal-cutting tools made out of tool steels.

3 cl, 1 dwg

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