KR100466271B1 - Method and system of treatmenting surface - Google Patents

Abstract

The surface treatment method of the casting, forging, and injection mold according to the present invention uses the electric discharge machining method to connect the positive electrode of the discharge electrode using the RC circuit to the vibrator to continuously generate spark discharges according to the vibration period, thereby treating the electrode material instantaneously. It is based on the principle that it is heated and melted, coated on the surface, and hardened by quenching effect. Electrodes used as treatment materials are applied in various ways depending on the purpose of use, such as tungsten carbide, titanium carbide, chromium-nickel, etc.The treatment materials are melted on the surface of the mold by discharge and are surface treated, so that the treatment materials (tungsten carbide, titanium carbide, chromium) Nickel) hardness can be obtained and wear resistance, corrosion resistance, heat resistance and the like can be improved depending on the intended use. Since the surface treatment time is short, the use of the mold after the surface treatment can be speeded up, thereby increasing the production volume, thereby reducing the cost and mass production.

Description

Method and apparatus for treating surface of mold using discharge hardening {Method and system of treatmenting surface}

The present invention relates to a method and apparatus for surface treatment of molds for extending the life of casting, forging and injection molds. More particularly, the present invention relates to electrical discharge phenomena, which applies to electrical discharge phenomena to coat and cure the surface of various materials and components. A method and apparatus for surface treatment of a mold using discharge hardening that enables the mold to be used again in a short time since the hardening layer and the growth layer can be formed on the mold by a short processing time by vibrating and rotating the discharge electrode in the method and apparatus. will be.

Molds used to inject a variety of plastic or metal powder has a problem that the material to be injected flows through the mold at a high speed and a severe force acts to cause abrasion of the mold, and to dig the mold locally. In addition, the casting mold is used at a high temperature, the wear of the mold itself occurs and the molten metal melts into the mold. In addition, the mold used for hot forging or cold forging has a problem that excessive momentary impact force acts on the mold excessively, as well as abrasion of the mold, and the mold is locally dropped or cracked.

In order to solve the above problems, casting, forging, and injection molds require hardness, wear resistance, and durability depending on use conditions, and a short period of reusing the mold in obtaining or repairing the hardness of the mold.

In order to meet these requirements, conventional methods have been used to heat-treat the mold surface, form nitrogen compounds or plate chromium, and form carbides such as vanadium in a molten borax bath. The hardness of the product obtained in Table 1 is shown in Table 1, and the properties of the surface layer formation are shown in Table 2.

fair Chrome plated Surface heat treatment Nitriding treatment Hardness of Hardened Layer (Hv) 900 to 1100 700-830 920-1050

fair Formation speed Processing temperature Processing time Remarks Chrome plating 0.03mm / hr 50 ℃ 5 hours Hard chrome plating Surface heat treatment 0.31mm / hr 1000 ℃ 8 hours Carburizing Nitriding 0.02mm / hr 500 ℃ 48 hours Gas nitriding

In the conventional surface treatment method described above, in the case of plating, not only environmental pollution caused by the use of the plating bath, but also the surface treatment time is long, resulting in a decrease in the yield. And workers' avoidance due to poor working environment is also a problem. Nitriding can achieve high hardness surface properties, but the surface treatment time is long and the process equipment and maintenance costs are expensive. In particular, many surface heat treatment methods have a disadvantage in that the production time is reduced because the time required for obtaining a hardened layer is quite long.

In addition, there is a welding method that is conventionally used to repair the damage when the mold is damaged, the welding method is the mechanical properties of the mold due to the heat input generated during the operation, the mechanical properties of the mold, such as distortion and the mold There are problems such as dismantling and repair, and preheating and pre / post heat treatment. In addition, there is a problem that it is difficult to process only the minute portion, the desired portion.

An object of the present invention for solving the conventional problems as described above is to apply a discharge hardening method and apparatus to shorten the surface treatment time of the mold and also to excellent characteristics of the resulting hardened layer to vibrate and rotate the discharge electrode The present invention provides a method and apparatus for surface treatment of a metal mold using discharge hardening for coating and fostering a discharge electrode in a shape.

1 is a circuit diagram showing a mold surface treatment apparatus using the discharge hardening according to the present invention

2 is a circuit diagram of a mold surface treatment apparatus according to the present invention.

3 is a view showing a rotary power tool according to the invention

4 is a view showing a vibrating power tool according to the present invention

Figure 5a is a view showing a change in the thickness of the formed cured layer according to the frequency change of the discharge curing apparatus according to the present invention

5b is a view showing a change in the thickness of the formed cured layer according to the output change of the discharge curing apparatus according to the present invention

6a to 6c is a photograph of the tungsten hardened layer formed on the surface of the cold forging die steel hardened by the discharge hardening apparatus according to the present invention

7 is a view showing the change in hardness from the surface of the forging die steel hardened by the discharge curing device according to the present invention;

Figure 8 is a view showing the X-ray test results of the tungsten hardened layer formed on the surface of the cold forging die steel hardened by the discharge hardening apparatus according to the present invention

Figures 9a and 9b is a photograph of the nickel growth layer formed on the surface of the steel for cold forging mold grown by the discharge hardening device

10a and 10b is a photo of the cold forging mold repaired by the discharge hardening device

11a and 11b is a photograph of the aluminum casting mold repaired by the discharge hardening device

An embodiment of the present invention for solving the above object will be described in more detail with reference to the accompanying drawings, FIGS. 1 to 11B below.

The surface treatment method of the mold using the discharge hardening according to the present invention, by placing the mold on the cathode and the discharge electrode on the anode to discharge while vibrating or rotating the discharge electrode, the material used as the discharge electrode on the mold is coated and When the discharge electrode is rotated, a plurality of RC parallel circuits connected in parallel with a resistor and a capacitor are alternately charged / discharged alternately, and when the vibration is performed, the spark cycle is continuously generated by adjusting the vibration period, thereby causing an electrode material. At this instant, the mold is heated and melted so as to be coated on the surface of the mold so that the mold is not heated so that the coating can be quickly cooled and cured.

Meanwhile, in the discharge curing method, the anode electrode may use a single metal electrode or an alloy electrode according to the purpose of use, such as tungsten carbide, titanium carbide, chromium-nickel, cobalt, and the like. By melting on the surface and surface-treating, the hardness of the treated material (tungsten carbide, titanium carbide, chromium-nickel, cobalt) can be obtained on the mold surface, and the wear resistance, corrosion resistance, heat resistance, etc. of the mold can be improved depending on the intended use.

In addition, the surface treatment apparatus of the mold using the discharge curing according to the present invention will be described below with reference to FIGS. 1 to 4.

In the surface treatment apparatus of the mold using the discharge hardening according to the present invention, as shown in Fig. 1, the mold 2 is applied to the cathode part of the power supply E using a parallel circuit of a resistor and a capacitor (hereinafter referred to as RC parallel circuit). Position the electrode rod 4 made of a material to be coated on the mold 2 by connecting to the rotary device 100 and the vibrator 200, so that the electrode 4 is vibrated and rotated. The material of the electrode 4 is rapidly discharged so as to be coated and cured on the mold 2. FIG. 1 shows a case where tungsten carbide (\ C) is coated on the mold, where W represents tungsten and C represents Represents carbide.

On the other hand, the electrical configuration of the surface treatment apparatus of the mold using the discharge curing shown in Figure 1 in more detail with reference to Figure 2, the rear end of the power input terminal (AC-IN) to the noise generated during the electrical discharge curing Connect a noise filter that removes before the AC-IN and does not affect other devices, and the DC power control unit (DIODE, TRANS, FET1, POWER-IC) is connected to the rear of the noise filter. And a plurality of RC parallel circuits RA-CA and RB-CB are discharged to the rotary tool DC_APP_OUT at the rear end of the DC power control unit so that sparks are generated. The reason for using a plurality of RC parallel circuits and switching means (SCRA, SCRB) is that when one side of the switching means (SCRA) is operating, the capacitor (CB) connected to the other switching means (SCRB) is charged and the other switching means (SCRB) During this operation, the capacitor (CA) connected to the other switching means (SCRA) is charged so that the time for charging can be omitted compared to when using one, and the continuous spark can be generated and the rotary tool (DC APPL) The object is discharged through the electrode. The vibration tool AC APPL generates an AC voltage and a frequency by the FETs 2 and 3 and u-COM, and discharges the coating onto the object through the vibration tool AC APPL electrode.

On the other hand, in the mold surface treatment apparatus, the rotating device 100 is mainly used to cultivate using a high output and can also be coated with a low output. Looking at the configuration with reference to FIG. 3, the power line 102 connected to the RC parallel circuit The carbon brush (CARBON BLUSH) 104 electrically connected to the shaft is installed on the shaft 108 of the motor 106 via the spring 110, and the chuck shaft CHUCK connected to the chuck CHUCK 112 holding the electrode. SHAFT; 114 is connected to the carbon brush 104 using a bearing 116, and these components are provided with a ceramic nozzle 118 at the front end and a gas nozzle 120 and a power line at which gas is introduced. By installing in the case 122 in which the 102 is installed, SPARK is generated while the metal electrode grounded by the earth wire and the electrode to which power is applied through the carbon brush 104 come into contact with each other. Let In addition, Ar gas, which prevents oxidation of the electrode during discharge, is introduced into the case 122 through the gas nozzle 120 to flow out to the electrode portion through the ceramic nozzle 118, and the carbon brush 104 ) Minimizes sparks at the contacts that may occur with the shaft 114 to prevent a reduction in rotational torque, the bearing 116 prevents shaking when the shaft 114 rotates, and the stopper 124 occurs when sparking Radiate heat.

In the mold surface treatment apparatus, the vibrator 200 is mainly used for coating at low power in a manner of discharging when the electrode rod contacts with the mold and charging when it is dropped. The configuration thereof is illustrated in FIG. 4. Looking at, the vibrator (VIBRATOR; 204) is installed inside the housing 202, the vibration damping spring 206 is installed on the outer periphery, the shaft 208 for fixing the electrode 4 to the vibrator 204 It is connected and installed, the shaft 208 is to adjust the amount of vibration when vibrating by the screw bolt 210, when the electricity is intermittently applied to the vibrator 204, the electrode is reciprocated before / after the vibration tool to operate do.

On the other hand, the electrode in the present invention described above uses a single metal electrode such as tungsten, titanium, nickel, cobalt, or an alloy electrode of these metals.

In the present invention, the switch power supply is used to increase the capacity and reduce the size of the equipment.

The results of the surface treatment method and apparatus of the mold using the discharge curing according to the present invention configured as described above will be described with reference to FIGS. 5A to 11B.

Figure 5a shows that the thickness of the surface hardening layer increases with increasing the frequency and the number of revolutions when rotating the electrode portion and the vibration of the advantages of the present invention, Figure 5b is formed on the mold surface as the external output voltage increases It shows that the thickness of the surface hardened layer is increased.

6A to 6C show a hardened layer formed on a mold surface when the mold surface is hardened with tungsten carbide.

In addition, Figure 7 shows the surface hardness of the cold forging die steel, which is the material to be treated, using tungsten carbide, and then irradiating the hardness change from the surface to the inside. It is 1500 or more and the contact portion between the material and the surface hardened layer has a hardness value of about 800.

8 is a view showing the tungsten carbide or tungsten compound layer formed on the surface of the mold surface-hardened with tungsten by X-ray diffraction, Figures 9a and 9b is a cross-sectional photograph of the surface and the growth layer grown on the cold forging die steel using nickel. 10A and 10B are pictures of cold forging molds repaired by the discharge hardening device, and FIGS. 11A and 11B are pictures of aluminum casting molds repaired by the discharge hardening device.

According to the present invention as described above looks at the effect of performing a surface hardening to various molds.

For casting molds, tungsten carbide (WC) is added to the die casting mold. Titanium carbide (TiC) cemented carbide coating process has the effect of erosion and sintering of the aluminum molten metal of the mold. Slip and abrasion prevention effect when tungsten carbide coating is applied to the pinji roller, tungsten carbide + cobalt (Co) coating treatment is applied to the drawing mold, and tungsten carbide coating is applied to the cell mold to prevent mold wear due to sand. There is an effect of repairing the part (parting) worn by sand during finishing treatment after nurture nickel (Ni) alloy.

In the case of forging dies, the punch and die life extension of the tungsten carbide coating on the hot-former has more than doubled the effect. In the case of drawing molds, it is possible to prevent slipping when the tungsten carbide + chromium carbide (CrC) coating is applied to the spring guide roll, and when the product is introduced when the tungsten carbide + titanium carbide + chromium carbide + molybdenum carbide (MoC) coating is applied to the drawing mold It is effective to prevent seizure of the bent part. In the case of plastic injection molds, the wear of tungsten carbide coating on the matte mold surface prevents mold wear and the tungsten carbide + chromium carbide coating on the injection mold prevents wear of the raw material inlet.Tungsten carbide + titanium carbide + chromium carbide + molybdenum carbide coating There is an effect of preventing feeder wear during processing.

And looks at the hardness of the surface layer according to the present invention with reference to Table 3.

fair Discharge curing Hardness of Hardened Layer (Hv) 1086-1159

And the formation properties of the surface layer according to the present invention is shown in Table 4.

fair Formation speed Processing temperature Processing time Remarks Discharge curing 0.05mm / hr Room temperature 0.5 hour Discharge curing

W Co 93.5 6.5

Fe Cr Ni Mo 7.9 15.6 60.9 15.6

In the above table, the hardness and surface layer characteristics were prepared using a hot mold as a base material, and the hardness value after the surface treatment was obtained at 1080 Hv or more, Table 5 shows the tungsten electrode components, and Table 6 shows the nickel electrode components. In units of Tables 5 and 6, the units are wt%.

Therefore, the surface treatment method according to the present invention can be used quickly after the surface treatment because the surface treatment method is convenient and the processing time is short, so that the formation or repair of a hardened layer can be performed in a short time, resulting in increased production and cost by mass production. Savings can be obtained. And according to the characteristics of the treated material can be improved wear resistance, corrosion resistance, heat resistance and the like.

Looking at the effects of the surface treatment method and apparatus according to the present invention as described above, conventional methods such as welding preheat the base material (mold) before the operation or heat during the operation to generate the temperature of the mold to raise and coating There is no quenching effect, but the present invention has excellent cooling effect because the processed material melts at the instantaneous high temperature and adheres to the base material and the temperature of the mold does not rise during the operation, and the cooling rate is high because the growth and thickness of the coating layer are thin compared to welding. The mold is repaired by using the same method as the conventional welding method. To repair the mold, no matter how small the defect is, it is necessary to separate the mold and remove the mold. (Furnace) etc., because the work must be done in a lot of time and cost, but according to the present invention Any place can be treated immediately wherever it is desired, thus reducing the surface treatment time in a broad sense.

Therefore, according to the present invention, since the convenience of surface treatment and the processing time are short, the use of the mold after the surface treatment can be speeded up, so that the formation or repair of the hardened layer can be performed in a short time, resulting in increased production and cost reduction by mass production. have.

In addition, compared with the chromium plating method, the environmental pollution is less and the treatment cost can be reduced, and the wear resistance, corrosion resistance, heat resistance, etc. can be improved according to the treatment material.

In addition, the present invention has a very small heat input, so there is no change in dimensional deformation and mechanical properties of the mold due to the heat input.

Claims (4)

delete In the surface treatment apparatus of a metal mold | die, A DC power control unit (DIODE, TRANS, FET1, POWER-IC) is connected to the rear end of the power input terminal (AC-IN), and a plurality of RC parallel circuits are connected to the rear end of the DC power control unit. A rear end of the RC (APP) is connected to the rotary tool (DC-APP) for rotating the electrode by the motor, the rear end of the RC parallel circuit switching means (SCRA) (SCRB) for controlling the energization of the rotary tool and the RC parallel circuit AC power supply for alternating current flow through the switching means (SCRA) (SCRB) in accordance with the frequency adjusted from the frequency control unit (FRQ-ADJ), and the rear end of the noise filter. (FET2, FET3, etc.) are connected in parallel with the DC power supply control unit, and a vibration tool (AC-APP) for controlling the oscillation period is connected to the rear end of the AC power supply control unit. Device. 3. The discharge hardening according to claim 2, wherein a noise filter (NOISE-FILTER) is connected to a rear end of the power input terminal so as to remove noise generated during the discharge curing from the power input terminal so as not to affect other devices. Surface treatment apparatus of the mold using. The chuck of claim 2, wherein the rotating tool installs a carbon brush 104 electrically connected to the power line 102 connected to the RC parallel circuit on the shaft 108 of the motor 106, and holds the electrode. The chuck shaft 114 connected to the 112 is connected to the carbon brush 104 using the bearing 116, and these components are provided with a ceramic nozzle 118 at the front end and a gas nozzle into which gas is introduced. 120) and the surface treatment apparatus of the metal mold | die using discharge hardening characterized in that it installed in the case 122 in which the power supply line 102 was installed.