JP2589976B2 - Electrode for discharge coating - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode for electric discharge coating, and more particularly to an electrode for composite electric discharge coating by electric discharge for imparting high hardness and wear resistance.

2. Description of the Related Art Conventionally, in this kind of discharge coating, an electrode for discharge coating is attached to a vibration device such as a vibration device which usually includes an electromagnet and a repulsion spring or a vibration device which rotates a biasing body having a rotation biasing shaft by a rotating means. To face the workpiece surface,
The electromagnet is excited by a predetermined oscillator or commercial alternating current, or further by a charging / discharging current or voltage of a discharging capacitor, so as to move up and down in a direction facing the workpiece to process the tip of the discharge coating electrode. Repeats contact-separation vibration on the body surface, and performs pulse discharge in the gap in synchronization with close contact, or supplies high-frequency voltage pulse from close proximity to a predetermined separation to perform micro-pulse discharge and pulse conduction multiple times The coating is performed by welding and bonding to the surface of the workpiece at the time of separation from the state in which the melted tip of the electrode for discharge coating heated at the time of contact is welded to the workpiece, and leaving the electrode. By performing relative scanning movement or scanning processing feed between the workpieces, a coating layer can be formed on the entire surface of the workpiece or on a necessary portion.

Problems to be Solved by the Invention Further, the present inventor has proposed that the electrode for discharge coating is rotated around the axis in the contact / separation direction during a period from at least close contact by the movement of the close contact / separation to separation. By giving a rotary motion, the coating surface becomes smooth with a small surface roughness and becomes a clean finished surface, the coating thickness can be thickened, the coating layer is more dense, there are no holes and weak spots, and the bottom of the coating layer It has been discovered that the coating is performed without the surface of the workpiece being very uneven, and has been proposed earlier.

In other words, by causing the electrode for discharge coating to be applied to the workpiece by simultaneously applying the vibration motion and the rotational motion of the contact separation,
Compared to the conventional simple vibration method, the coating layer is not porous with a uniform thickness overall, the coating speed is high, the coating amount and thickness are large, and the coating surface roughness is small and good. Can be obtained.

However, even with the improvement of the discharge coating method and equipment, the thickness and hardness of the coating, or the uniformity of the coating, the elimination of weak spots, and the surface roughness are still not satisfactory.

Further, as in the application field of the present invention, in order to mainly impart high hardness and wear resistance to the surface of the metal to be treated, tungsten carbide (WC), titanium carbide (WC) is mainly used as the electrode for the vibration discharge coating. TiC), or tungsten (W), titanium (Ti) based cemented carbide, etc., is used for the discharge coating.
Depending on the electrodes used conventionally, the possible coating amount (mainly the coating thickness) is small, or the metal surface to be processed cannot be uniformly and densely coated, or the surface roughness of the coating surface is large. However, there are disadvantages such as that a smooth and clean surface cannot be obtained, or that a coating is extremely difficult to be formed with an electrode of a target material. For this reason, the present inventor has previously proposed tungsten (W), titanium (Ti), tantalum (Ta), hafnium (Hf), niobium (Nb), molybdenum (Mo), and vanadium (V) as improvements in the electrode for discharge coating. , Zirconium (Zr), silicon (Si), chromium (Cr) or boron (B) at least one carbide of cobalt (C
o), at least one kind of nickel (Ni) or iron (Fe) is used as a binder, and 3 to 30% by weight is added and sintered. % Copper (Cu) containing an electrode for discharge coating,
The application has been published as Japanese Patent Publication No. 56-9258.

That is, it is a conventionally known metal carbide-based sintered cemented carbide in which copper is contained as an effective component, and it is intended to improve the coating thickness without greatly sacrificing the hardness, but is practical. There is not yet a satisfactory one.

Means for Solving the Problems However, the present invention has been further studied variously with respect to the coated electrode material, and has been described as a discharge coating electrode material containing columnar or rod-shaped boron B as an active ingredient, and also tungsten W, tungsten carbide WC. , Boron nitride BN, titanium T _i , carbon C, silicon S _i ,
Boron trioxide B ₂ O _3, phosphorus P, nickel N _i, or cobalt C _o 1 or more electrode material of the columnar or rod comprising at least one or more of, is caused to face each other during discharge cladding process Each of the electrode members is adjacently juxtaposed in a direction parallel to the surface of the workpiece so as to be in close contact with each other, and is united or bonded together. Preferably, argon gas, nitriding gas, In a non-oxidizing atmosphere such as a silane gas or a hydrocarbon gas, the coating electrode is rotated to perform a pulse discharge between the workpiece and the workpiece while the coating is being performed, thereby coating the workpiece with a non-oxidizing atmosphere having a higher hardness than before. This is to provide a crystalline surface coating. In addition, boron B has already been effective in improving and maintaining the hardness of the coating, and it has been obtained through various experiments and trial productions that a part of the boron B also acts as a binder such as oxidation and carbonization. I have.

According to the present invention, it is possible to obtain an amorphous surface coating having a higher hardness than the conventional one.

FIG. 1 is a side sectional view of an apparatus suitable for performing a coating operation using the electrode for discharge coating according to the present invention. 2 As shown in FIGS. 2 (a) and 2 (b), a columnar or rod-like body that is not very long as a whole, and in the case of FIG. 2 (a), an electrode material containing a columnar or rod-shaped boron B as an active ingredient, for example a boron 1a, alloying, reaction or the like by a coating material electrode material for example WC-6% C _o 1b, titanium W ₁ 1c, and an electrode material 1b~1d of the columnar members to the rod-shaped body of graphite C1d, The iron material (SK
3) In the direction parallel to the surface of the workpiece 2 such as described above, the electrode materials 1a to 1d are molded so as to be in close contact with each other as appropriate, and in the case shown in the drawing, they are integrated in a quarter-arc cross-sectional shape to form a circle. They are arranged adjacent to each other to form a columnar body and combined or bound.
In the case of (b), each electrode material such as the column is a plate-like body,
Those from multiple overlapping conjugates of the plate-like body structure, such as a cut out cylinder, for example, 1f the _{WC-6% C o -0.1%} P, 1
g boron B and titanium mixture, 1h graphite C, 1j is titanium T _i and 1k is as graphite C.

For example, in the case of the above-mentioned FIG. 2 (a), as shown in FIG. 3, the method of manufacturing such a discharge coating electrode 1 is to form a sintering die 10 having a cylindrical shaped hole 11 filled with a sintering material. The hole 11
Then, each desired electrode material 1a ~ 1d powder is filled into a desired cross-sectional shape, and the two sides of the hole are energized while being pressed with graphite punches, for example, heated to about 1100 ~ 1200 ° C for 10 minutes. , Which can be formed by sintering under pressure.
In this way, the coating electrode 1 is formed with the various metals inserted in the form of layers, etc., although a part thereof becomes an alloy at the boundary between the layers. Reference numeral 2 denotes a workpiece to be coated such as an iron material, which faces the electrode 1 for electric discharge coating, a power supply 5 for processing is connected between the two, and an intermittent voltage pulse is supplied. Reference numeral 4 denotes a support shaft having a fixed mounting support chuck 4a for the discharge coating electrode 1, which is connected to the rotating shaft of the micromotor 3. The support shaft 4 is connected to and held by a later-described vibrating piece 6a by a connecting portion 8 having a bearing 8a. Reference numeral 6 denotes an apparatus main body which is attached to a hand-held head or a mechanical apparatus head. An electromagnetic vibrating apparatus 7 having a vibration exciting wire 7a and a vibrating piece 6a are attached thereto. An iron piece 6b is provided opposite to the magnetic pole of the device 7 and vibrates integrally with the vibrating piece 6a. The vibration accompanying the suction release of the iron piece 6b by the electromagnetic vibrating device 7 is applied to the micromotor 3 provided at the free end of the vibrating piece 6a, and thus to the support shaft 4 connected to the rotation shaft of the micromotor 3. Thus, the electrode 1 performs the contact and separation by vibrations on the workpiece 2 while rotating around its axis, preferably an eccentric axis. Accordingly, when the discharge coating electrode 1 descends and comes close to the workpiece 2 and the gap becomes equal to or smaller than the dielectric breakdown gap, a discharge is generated by a voltage pulse applied from the machining power supply 5, and the discharge coating electrode 1 is discharged. Is melted and softened by the discharge heating at the tip of the electrode 2 and then the contact current heating in the state of contact with the workpiece 2 so that the adjacent electrode materials mainly react with each other while mixing or alloying. Transfer welding. At this time, if the electrode for discharge coating 1 is rotated about the central axis of the axis or an appropriate eccentric axis, the electrode 1 is relatively rotated and rubbed by rotation before separation. In this state, the discharge welded portion is torn apart, thus breaking apart while leaving a jagged surface with a large surface irregularity and a high surface roughness as in the prior art. The fractured or coated surface is adjusted by rotary rubbing, and the surface of the workpiece 2 is sequentially scanned so as to be stroked, so that a smooth finished surface with a small surface roughness can be obtained as a whole. Is very unlikely to have an uneven surface due to light tapping of the vibration, and the coating thickness can be increased without any partial weakness. When the electrode 1 is rotated around an eccentric axis as described above, the mode of the discharge coating process is combined with the above-described configuration of the electrode 1 for discharge coating according to the present invention to constitute the electrode 1 for coating. Electrode material 1a ~
The mixing reaction or alloying between 1d, 1f to 1k is promoted in various ways, and the boron B arranged as an active ingredient in the electrode material 1a for the mixing reaction and alloying of the electrode materials is good for each part of the entire coating. As a result, the probability of forming a coating having high hardness and high abrasion resistance is increased, and a discharge coating having higher quality and better characteristics than conventional discharge coatings can be obtained.

As described above, when the coating electrode 1 is coated on the workpiece 2 while vibrating in contact with the workpiece 2, effective cooling is also an important factor.

The electrode of the electromagnetic vibration device 7 and the discharge coating power supply 5 are connected to a capacitor charge / discharge type pulse power supply or a pulse power supply in which a DC voltage is intermittently generated by an electronic switching element such as a transistor to generate a voltage pulse having a pause. Can be used.

Effect of the Invention In this manner, the composite discharge coating electrode 1 of the present invention is decomposed into a non-oxidizing atmosphere such as an inert gas of argon Ar, a nitriding gas of Ni, and a hydrocarbon gas of H ₆ C ₆ , that is, oxygen is generated. The electrode 1 is made to face the surface of the workpiece 2 in the axial direction in a state where no
In the case of a coating electrode in which various metals are arranged radially or in a layer by moving it while applying vibration of about 300 to 400 K / Hz, various metals are uniformly coated, and the coating electrode is arranged in a cylindrical shape In this case, the width near the center is narrow, and the outer periphery is covered with a wide metal band as if they were overlapped. In each of the coatings, various metals are coated in an amorphous state, and the hardness of the coated composite is as high as Hv 5500 to 7000. Examination by X-ray revealed that the coating layer when coated in a nitriding gas atmosphere was B ₄ C, TiB ₂ , Ti
Composite compounds such as N, CBN, _Fe3N , and FeB, which are almost amorphous and form a complex compound such as various carbides, borides, and silicides even when coated in an argon gas atmosphere. Was obtained.

The following table shows examples of experiments in which a coating process was performed using the electrode for discharge coating of the present invention, together with experimental conditions and results of the coating process.

Thus, the present invention enables discharge coating with extremely high hardness.

[Brief description of the drawings]

FIG. 1 is a simplified configuration diagram of a discharge coating apparatus suitable for use in the embodiment of the present invention, and FIGS. 2a and 2b are different composite electrode slope views.
FIG. 3 is a simplified diagram showing a state in which the holes 11 of the die 10 are filled with various metals shown in FIG. In the figure, 1 is an electrode for electric discharge coating, 2 is a workpiece, 3 is a motor, 4 is a support shaft, 5 is a power supply for electric discharge coating, 6a is a vibrating reed, 6b is an iron piece, 7 is an electromagnetic vibrating device, and 7a is for excitation. Wire loop.

Claims (1)

(57) [Claims] An electrode material for discharge coating containing columnar or rod-like boron B as an active ingredient, and tungsten W, tungsten carbide WC, boron nitride BN, titanium T _i , carbon C, silicon S _i ,
Boron trioxide B ₂ O _3, phosphorus P, nickel N _i, or cobalt C _o 1 or more electrode material of the columnar or rod comprising at least one or more of, is caused to face each other during discharge cladding process An electrode for discharge coating, wherein the electrode members are arranged side by side so as to be in close contact with each other in a direction parallel to the surface of the workpiece, and are united or bound together.