JPS58197274A - Electric discharge coating device - Google Patents

Abstract

PURPOSE:To provide an electric discharge coating device which is constituted to form a thick and dense coating layer with small surface roughness and smoothness of the coating surface, by applying rotating motion around a shaft in the attaching and detaching directions to an electrode of a coating material during the period from the stage of attaching until detaching. CONSTITUTION:As an electrode 1 of a coating material descends and approaches the work 2 and the spacing therebetween attains a breakdown spacing, electric discharge is generated by the voltage applied on the electrode 1. The forward end of the electrode 1 is melted by the electric discharge heating and the contact electrical heating in the state of the contact upon the contact of the electrode with the work 2 that takes place next to the discharge heating. The molten electrode is transferred and welded to the work 2. Since the electrode 1 is kept rotated around the shaft thereof during said time, the welded part by electric discharge is torn off by the rotation of the electrode so as to rub off the welded part prior to detaching. The surface of the work 2 is formed to a smooth finish surface by the breakdown or the control of the coated surface by the rubbing as well as the electric discharge generated upon starting of the contact by the oscillation with the rotation, whereby the electric discharge coating having less cavities and weak parts of the coating is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves arranging a coating electrode that repeatedly applies close contact and separation vibrations to the surface of a workpiece, and performing contact and separation vibration between the electrode and the workpiece, As the close contact and separation occur, an electric discharge is generated, and the molten portion of the tip contact portion of the coating material electrode is coated on the surface of the workpiece by transfer welding! Concerning the improvement of covering methods.

Conventionally, with this type of discharge liquid, the coating material electrode is attached to an i-motion device such as a vibrating device composed of an electromagnet and a repulsion spring, or a vibrating device that rotates a biased body having a rotational bias axis using a rotating means. The electromagnet is placed facing the body surface and excited by an oscillator, a commercial alternating current, or even a charging/discharging current or voltage of a discharge capacitor, so that it moves up and down in the opposite direction to machine the tip of the coating material electrode. Repeat contact and release vibrations on the body surface, synchronize with the time of close contact to cause a pulse discharge in the gap, or supply high frequency voltage pulses from the time of close contact to the time of predetermined release to perform minute pulse discharge and energization multiple times. The coating is performed by the melted part of the tip of the coating material electrode that is heated during contact with the workpiece being welded to the workpiece, and then remaining welded and bonded to the workpiece surface when separated, and there is no gap between the electrode and the workpiece. By performing relative scanning movement or scanning processing feed □A, a coating layer can be formed on the entire surface of the workpiece or a necessary portion.

However, if the workpiece electrode is simply tapped against the workpiece surface by vertical movement in the opposite direction to make contact and release, the melted portion of the coating electrode will not melt. It is welded to the surface of the workpiece during light contact, and when the coating electrode is pulled up and separated, the molten welded part is broken, for example, approximately at the midpoint between the surface of the workpiece and the tip of the coating electrode, and the electrode material is removed. Since the coating is carried out by welding and leaving it on the body surface, the fractured surface, that is, the coated surface, has a jagged surface with large irregularities, which has the disadvantage that the coated surface cannot be finished neatly. Also! Due to the light contact and separation with the tip of the rod, the wave force Loe body surface becomes uneven, the covering material does not adhere to the workpiece surface uniformly, the vertebral surface becomes uneven G, T, and the covering layer becomes pinned. There were many rather large holes and weak points rather than holes, and the amount and thickness of the coating were small, and the density of the coating layer was also low.

In view of these points, the present invention was developed as a result of various studies, and the present invention has been developed as a result of various researches, and the present invention has been developed as a result of conducting various researches. By applying rotational motion around the axis in the away direction, the coated surface can be smoothed with less surface roughness, resulting in a clean finished surface, allowing the coating to be thicker, making the coating layer more dense, and eliminating holes and weak points. In addition, the surface of the workpiece under the coating layer does not become very uneven and can be coated.

Furthermore, the present invention provides a coating material for a workpiece in an inert gas such as argon, a reducing gas such as hydrogen, or a mixture thereof, an equivalent gas, vapor, or even a liquid. This method is characterized in that the electrodes are subjected to vibrational movement and rotational movement of contact and separation at the same time.

The present invention will be explained below with reference to the embodiments shown in the drawings.

FIG. 1 is a side sectional view of a device according to an embodiment of the present invention, in which numeral 1 is a rod-shaped body such as a 6% Co-balance Wa sintered body.

A short cylindrical or pipe-shaped covering material electrode 2 is a workpiece made of iron material, for example, and faces the electrode 1, and a machining power source 5 is connected between the two to apply intermittent voltage pulses. Supplied. 4 is a fixed mounting support chuck 4 for the covering material electrode 1;
The rotation of the motor 6 provided in the main body 6 is applied to the support shaft 4 through the pulley 3a, the belt 3b, and the boot IJ3c. On the other hand, 6 is a device main body constituting a vibrating head, and 6a is a vibrating piece made of a spring material, the other end of which is fixed to the main body B so that it can vibrate. is fixedly provided. Reference numeral 7 denotes an electromagnetic iron core, which is provided so that the iron pieces 6b are opposed to each other at intervals, and an excitation wire ring 7a.
is wrapped around a part of it. In the illustrated case of the vibrating piece 6a, reference numeral 8 denotes a vibrating end coupling portion for imparting vertical vibrating motion to the covering material electrode 1 via the support shaft 4, and the support shaft 4 is rotatably held on the vibrating piece 6a by a ball bearing 8a. It's been done. In addition, the workpiece 2
is provided at a position opposite to the covering material electrode 1, and a machining power source 5.
Either more intermittent Takaoka 6-wave voltage pulses are applied, or one voltage pulse causes one discharge to occur synchronously with close contact separation. On the other hand, the covering material electrode 1 is.

It is connected and held to a support shaft 4 so that it moves together, and the support shaft 4 is connected to a pulley 3a and a bell by a motor 3.
31) and a rotational motion around the shaft via the pulley 3c, and the excitation wire 7a of the electromagnetic vibration device 7.
By intermittently applying excitation at a predetermined frequency or the like, the iron piece 6b is attracted and released, and the vibrating piece 6 integrated with the iron piece 6b is
Since a is made of a spring material and is held in the main body 6 so that it can vibrate elastically, the suction release G of the iron piece 6b also vibrates, and this vibration? By applying it to the support shaft 4 through the coupling portion 8P provided at the vibration output end, the support shaft 4. That is, electrode 1
While rotating around its axis, it contacts and separates from the workpiece 2 by vertical vibration motion.

Therefore, as the covering material electrode 1 descends and approaches the workpiece 2, when the gap becomes less than the dielectric breakdown gap, an electric discharge occurs due to the applied voltage of the machining power supply, and the tip of the covering material electrode 1 The material is melted by radiation heating, then brought into contact with the workpiece 2, and contact current heating while in contact, and is transferred and welded to the workpiece 2. At this time, since the covering material electrode 1 is rotating around its axis, the discharge welded portion is torn off by rotation or even rubbing before separation, and therefore, unlike the conventional method, Unlike a fracture that leaves a jagged surface, this fracture or the surface to be abraded is adjusted by rotational rubbing, and the surface of the workpiece 2 is stroked by the contact separation discharge of the vibration accompanying such rotation. A smooth finished surface can be created by sequentially scanning the surface, there are fewer holes and weak points to be exposed, and the coating thickness is thick and the density of the coating layer is high, so the amount of coating is large, and it is possible to create a smooth finish on the coating substrate. The surface of the workpiece has less irregularities and has excellent peel resistance.

Figure 2 of the drawings is a side sectional view of a different embodiment of the apparatus used for carrying out the method of the present invention, in which the same components or the same working elements as in Figure 1 are given the same reference numerals.

In this embodiment, the motor that rotates the support shaft 4 of the covered electrode 1 is a small micromotor 3A, and the motor is connected to the support shaft 4 directly or via an appropriate gear box by a coupling part 8 at the vibration output end by a mounting member 3B. It is configured like this,
The configuration of other parts is substantially the same as that of Figure 1 above.

In the embodiment shown in Figure 2, the motor 3A is directly fixed and attached to the coupling part 8 of the vibration output end, and the support shaft 4 or the electrode 1 attachment chuck 4a is attached to the rotational output shaft of the motor 3A. When configured as follows, the support shaft 40 rotatably mounted bearing 8a for the vibrating piece 6a in the above embodiment
can be omitted.

In the case of such a spear 2 @ and the configuration with a changed figure of the spear 2, electricity is supplied from the power source 3 to the electrode 1 through the rotating shaft of the micromotor 3A,
Support shaft 4. The chuck 4a or the electrode 1 is energized by the appropriate configuration of the plug.

9- The present invention will be explained below with reference to Examples.

In Fig. 1 or Fig. 2, a conventional electromagnetic vibration device having no rotating means is used for the electrode 1 or the support shaft 4, and a DC voltage is intermittent by a transistor switching element as the power source 5, so that the voltage has a rest time. If a pulse power source that generates pulses (conventionally used pulse power sources were often capacitor charge/discharge type), various combinations of conditions can be considered, but it is difficult to determine which one is best based on the mechanical vibration characteristics of the vibration device. This is not to say that a good coating will be achieved even under such set machining conditions.1For example, if the no-load voltage of the voltage pulse is approximately 50V, the voltage pulse width (r□N
) Approximately 80 μS, pause width (τ0FF) approximately 20 μ8, discharge current width (engine p) approximately 7'OA There is one electrical condition that is good for discharge coating, but in this case, the vibration of the vibration device for contact/release. There are places where the frequency is around 300 Hz, where the coating thickness or coating amount per unit area becomes maximum and good coating is performed. Material-10-1! When coating a BKH9 fired human workpiece using a pole, the coating amount (thickness) reaches almost saturation after scanning a 10 mt area for about 5 minutes, and the coating amount (thickness) reaches a maximum of about 18 to 20 mm.
m y/am” (average coating thickness approximately 12-13 μm
) The roughness of the surface to be processed is approximately 80μmRmax, and the hardness of the coated surface is approximately 12DDHv.When looking at the cross section, the surface of the workpiece of the lateral base material has an uneven surface with large undulations due to being struck by the electrode. In addition, the coating is locally thickly deposited in the form of small mountains or hills, and in areas where it is only thinly deposited, or in areas between some peaks of the coating, there is almost no deposit. The coating was in a kind of porous state with some parts that appeared not to be covered, and some of the protruding parts of the coating were likely to fall off. According to the above vibration and voltage pulse conditions, at least three or more voltage pulses are generated during one vibration from when the electrode approaches the surface of the workpiece and the first discharge occurs until it separates. It is thought that the discharge 1:' and the pulse energization at the contact area are occurring.

Therefore, under the above-mentioned discharge liquid I condition, the electrode is rotated around the axis according to the present invention at a rotational speed of about 100O.
R, P, M (approximately 1 rotational speed when the electrodes are close to each other, in a state where the electrodes are in close contact or close to this until they are separated), the coating amount is approximately 30 to 36 mp/m within approximately 2 minutes. am”
(The average coating thickness is approximately 20 μm, and the overall uniformity is high.)
Roughness on two surfaces is approximately 15μmRmax, hardness of the coated surface is approximately 120
When looking at the cross section at around 0Hz, the thickness is uniform throughout,
The coating was thick, dense, and flat, with almost no irregularities on the surface of the workpiece, and there was no problem with part of the coating falling off or peeling off. In the case of the above-mentioned coated strip gauge, it seems that good results cannot be obtained if the rotation speed of the electrode is too slow or too fast; Number to number 1 per vibration
within OR, P, M] seems to be preferable.

In addition, various machining conditions were examined when using the electrode rotation method as described above, with the contact separation frequency (approximately 300 Hz) and rotation speed (approximately 1.OOOR, P, M) being constant. It seemed better to make the voltage pulse a little larger, and it seemed preferable to increase the voltage pulse width for the discharge conditions for electrical discharge coating. Examples are as follows. The materials of the electrode and the workpiece were the same as in the previous case, with the electrode having a diameter of approximately 15 mm and the machining surface having a radius of 80 mm.
It is assumed to be a spherical surface.

τON τOFF Work p Coverage amount Coated surface roughness μE3) (μB) (A) ,
(m7/m1n) (μmRmax)A, 5[]0
2o 72 20
8B, 1000 40 72
21~24 7~80.2000 40
7.2 22 11A above
, B, and O, the coating layer has a uniform thickness throughout, is not porous, and the coating speed is about twice that of the conventional vibration method, but the amount and thickness of the coating are very different. (approximately 4 times), and the coated surface roughness was good. In addition, in the above case, the voltage pulse condition for coating B seems to be the most preferable condition, but in the conventional vibration method, the electrode material wC.

Or perhaps the carbon in the workpiece is decomposed and liberated, and the electrode immediately burns bright red and the coated surface turns black, making it almost impossible to coat the target cemented carbide at all.

Further, the present invention further provides a structure in which the coating material electrode 1 is brought into contact with and released from the workpiece 2 and simultaneously rotated on its own axis, using an inert gas such as argon, nitrogen, or carbon dioxide gas, hydrogen, ammonia.

- Coating processing is carried out during spraying or in a reducing gas such as carbon oxide, or a mixture thereof, or a liquid thereof, and the result is calculated as a coating speed m y/m.
In, cm" is shown on the vertical axis and the machining time min is on the horizontal axis. Curve A is when a capacitor charge/discharge type machining power source is used, and curve B is when the switching element is turned on as described above. , when using a voltage pulse type machining power source that is turned off, and there is no specific gas in either case 9
Curves C and D are for a mixed gas atmosphere of hydrogen gas and argon gas.In curve C, there is more argon gas than hydrogen gas (approximately 7:3), and in curves This is a case where the amount of hydrogen gas is greater than that of argon gas (approximately 7:3). As is clear from a comparison between curves A and B and curve C1D, the coating speed is approximately twice as high for the same coating processing time.

The current pulse conditions for curves B, O, and D in the figure are p: 6OA.
.

τON: 80μs, τ0FF=20μs, 6%Co-
With the remaining WC electrode, vibration 300H2, rotation speed approximately 100O
R0P.

M, and the coating thickness is 0.02 mm to [1,
It can be processed to 1mrr. Also, in an argon gas atmosphere, argon gas is applied at a rate of about 10 Q c/min.
A rotating electrode (approximately 1.5 mmφ
Bundle 12 pieces of 6% co-we wire to make approximately 300 OR
.

Rotate with P and M. ), the roughness of the machined surface was extremely improved.

Figure 4 is a diagram comparing the machined surface roughness between the conventional method and the present invention method in such a case.The conventional method has a machined surface roughness of about 46 μmRmax, while the present invention has a machined surface roughness of about 5 μmRmax and the conventional method. When the method was run in air, the Rmax was approximately 95 μm.

Incidentally, an inert or reducing gas, or a mixture thereof, or a liquid may be injected directly onto the discharge coating portion, or may be stored in such an atmospheric gas.

[Brief explanation of drawings]

Fig. 1 is a schematic block diagram of one embodiment of the present invention, Fig. 2 is a schematic block diagram of another embodiment of the apparatus, and Figs. It is a comparative characteristic diagram. In the figure, 1 is a covering material electrode, 2 is a workpiece, 5 is a processing power source,
4 is a support shaft of the covering material electrode 1; 5 is a motor for rotating the electrode; 6
a is a vibrating piece, 7 is a vibrating device, and 8 is a coupling portion. Fig. 1 Horse 2 Fig. Hanging 3 Fig. min Processing time Fig. 4

Claims (4)

[Claims] (1) Place a covering material electrode that gives vibration of contact and separation on the surface of the workpiece, connect the machining power supply signal between the electrode and the workpiece, and apply intermittent voltage pulses. In an apparatus for welding and coating a coating material electrode on the surface of a workpiece by electric discharge, a rotating means for performing the contact and separation while rotating the coating material electrode around an axis in the contact and separation direction is a vibration device. A discharge coating device, characterized in that it is provided in a vibrating part of. (2) The vibrating device is an electromagnetic vibrating device, and a supporting shaft of a material electrode is rotatably supported by a vibrating piece of the vibrating device, and a rotating means is coupled to the supporting shaft. The discharge coating device according to item 1. (3) Placing a covering material electrode that applies contact/separation vibrations to the surface of the workpiece, connecting a machining power source between the electrode and the workpiece, and applying intermittent voltage pulses. An apparatus for welding and coating a covering material electrode on the surface of a workpiece by electric discharge, the apparatus comprising a rotating means for performing the contact and separation while rotating the covering material electrode around an axis in the contact and separation direction, and Make the surface of the processed object inert or reducible,
Alternatively, a discharge coating method characterized by comprising means for creating an atmosphere in a mixed gas or liquid. (4) The discharge coating method according to claim 3, characterized in that an inert or reducing gas or liquid, or a mixture thereof, is ejected directly onto the discharge coating portion.