JPS6333580A - Discharge coating device - Google Patents

Abstract

PURPOSE:To increase the coating speed of the title device and to improve the smooth ness of a surface to be coated by supplying vibrational energy from an excitation electric power source provided with a PWM modulation circuit to an electromagnetic vibrator for attaching and detaching the electrode of a coating material in the dis charge coating device to and from an article to be coated, and vibrating the electrode. CONSTITUTION:The electrode 2 consisting of a carbide material, for example, is attached and detached to and from a metallic material 1 to be coated and vibrated by an electromagnet 5 provided with a coil 6, a magnetic body 9, and the resiliency of a vibrating read 8. Pulse discharge is generated by the terminal voltages of a capaci tor 3, and the electrode 2 is transferred and thermally sprayed on the surface of the material 1 to be coated. In this case, the PWM modulation circuit 7 is provided to the excitation power source for vibrating the electrode 2 consisting of the magnetic body 9 and the electromagnet 5 to pass an oscillating current with the controlled pulse duration of pulse discharge through the current vibrating coil 6. Consequently, the electrode 2 can be optionally detached from the material 1 to be coated and vibrat ed, the surface of the material 1 can be coated with the electrode material at high speed, and the roughness of the coated surface is reduced.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to electrical discharge coating processing in which the electrode material is welded and coated on the workpiece by applying a pulse discharge in the gap between the electrodes while contacting and separating the electrode from the workpiece and vibrating the workpiece. Regarding equipment.

[Prior art]

An example of a conventional coating processing apparatus is shown in FIG. Reference numeral 1 denotes a workpiece, and 2 an electrode, which is attached to a support 4 and faces the workpiece 1 with a contact amount +msa. 3 is an electrode, an impact capacitor for pulse discharge connected in parallel to the gap between the workpiece,
Reference numeral 5 denotes an electromagnet that vibrates the electrode 2, which applies an attractive force to a magnetic body 9 fixed to a vibrating piece 8 made of a spring material fixed to a support 4, and this electromagnetic attractive force and the repulsion spring of the vibrating piece 8 Vibrate by force. Reference numeral 6 denotes an Ili stone coil, which is excited by the terminal voltage of the M electric device 3, vibrates the electrode 2, and causes the workpiece 1 to vibrate in contact and release. The vibration causes a pulse discharge by the capacitor 3 to occur in the gap between the electrodes 2 and 2, and the molten portion of the electrode 2 at the discharge point comes into contact with the electrode 2 and transfers and welds to the workpiece 1 as a deposit. By repeating this electrode vibration and discharge and moving and scanning the contact point, a required coating layer is formed on the surface of the workpiece 1. If the material to be coated on the electrode 2 is, for example, a superhard material, the surface of the workpiece 1 can be hardened and wear resistance can be imparted.

〔problem〕

In the conventional device described above, in order to increase the coating processing speed, the electrode vibration device is improved and the electrode vibration is performed using the charging voltage of the discharge capacitor 3, thereby repeating vibration and discharge. , it is not possible to arbitrarily increase the frequency of vibration to a desired value, control the pressing force at the time of contact, control the vibration amplitude, etc., and increase the machining speed sufficiently;
The machined surface roughness could not be reduced.

[Means for solving problems]

The present invention has been proposed in view of these points, and is characterized in that a PWM modulation circuit is provided in the excitation power source for electrode vibration, and vibration control is performed using pulses modulated by a signal.

(Example) The present invention will be explained below with reference to an embodiment of the drawings.

FIG. 2 shows an example of a vibration excitation power supply equipped with a PWM modulation circuit 1, in which 71 is a comparison wave generation circuit, 72 is a level comparison circuit, and 73
is the sample and hold circuit.

A signal from the coating gap is inputted to the terminal 10 as a modulation signal. A transport pulse is input to the terminal 11.

The modulated signal is sampled and held 73, and compared by a level comparison circuit 72 using the comparison wave input generated from the comparison wave generation circuit 11 to obtain a PWM modulation output.

For example, if the oscillation frequency of the comparison wave generation circuit 71 is IK)lz, the modulation pulse τon is 0<τOn(1
If the gap voltage between the workpiece 1 and the electrode 2 is detected and inputted as the modulation signal input to the terminal 10, then when the gap voltage decreases, the modulation pulse width τOn becomes small and vice versa. When the gap voltage increases to τon
A modulated output is generated so that the The PWM modulated wave generated in this way is applied to the transistor of the amplifier 12, and after amplifying the power, excites the coil 6 of the electromagnetic oscillation device. When the electromagnet 5 is excited with a pulse with a large τOn, it strongly attracts the magnetic body 9 and vibrates, bringing the electrode 2 into strong contact with the workpiece 1. When excited with a pulse with a small τOn, the electromagnet 5 strongly attracts the magnetic body 9 and vibrates, and when it is excited with a pulse with a small τOn, the electromagnet 5 contacts the workpiece of the electrode 2. Vibration control is performed to weaken the contact pressure to the body 1. Therefore, while the gap voltage is high due to stable normal discharge, vibration is performed with strong contact pressure between the electrode 2 and the workpiece 1, and when the gap condition is poor and unstable discharge occurs and the voltage decreases, the electrode 2 and the workpiece 1 are vibrated. The workpiece 1 is controlled to vibrate with a weaker contact pressure. Vibration control according to this gap adaptively controls electrical discharge coating machining, and by continuing stable optimal machining, it is possible to increase machining speed and form a good coating layer with reduced surface roughness.

As the modulated signal detected from the coating gap, the current flowing due to the discharge, the sound pressure of the discharge, the radiated heat, the temperature of the electrode, the workpiece, etc. can be detected and used by each detection element. Further, a plurality of signals can be used in combination. Further, by using direct current as a modulation signal, any duty pulse can be output by voltage control, and the optimum vibration can be easily selected.

FIG. 3 shows an electrode vibrating device in which a permanent magnet 10 is provided opposite to an electromagnet 5, and the electromagnetic coil 6 is subjected to dual-wave excitation by applying the force of τOn and τoff pulses by PWM output, and is attracted during different polarity excitation. This is an example in which the vibrating element 8 is vibrated by utilizing repulsion during homopolar excitation. When using this permanent magnet 10, it is possible to vibrate at a higher frequency than when using the repulsive force of the spring shown in FIG. While a normal spring type has a response speed of about 300 to 420 H2, experiments have shown that when rare earth magnets are used, the frequency can be increased to about 440 to 510 H2.

FIG. 4 shows an embodiment in which an electromagnet 51 is used instead of a permanent magnet, and the vibrating element 8 is vibrated by alternately excitation of the same polarity and excitation of different polarity in the coils 6 and 61, and the vibration characteristics are as follows. The same effect as shown in the figure can be obtained. Incidentally, the vibration frequency can be controlled by the oscillation frequency of the comparison wave generation circuit 71, and it is preferable to perform switching control depending on the coating material and the coating purpose.

Also, in FIGS. 3 and 4, the electrode 2 is attached to the vibrating piece 8 when the electromagnet is fermented, contrary to FIG. 1.
vibrates when touched.

Next, the experimental results will be explained in detail. WC is used for the covering material electrode.
When applying deposit coating to 855C material using a carbide tip, the pulse h'l electric conditions for processing are as follows:
With the workpiece as a cathode, jp=80A, τon=10
Pulse discharge of μs was performed. The vibration of the electrode has a frequency of 50
At 0H2, detect the voltage in the gap using PWM control and use it as a modulation signal to convert 00 to 10 to 100 with the pulse width of vibration energy.
The time was controlled to 0 μs. That is, when the gap voltage is high, τon
When the gap voltage is large, τOn is small and when the gap voltage is low, it is modulated so that τOn becomes small, and when the oscillating electromagnet is half-wave excited and oscillated by this modulated pulse, it is defined as (A>), and the electromagnet is double-wave excited using a permanent magnet. (B), and detects and modulates the thermoelectromotive force between the electrode and the workpiece using the voltage when short-circuited, and outputs a PWM modulation pulse as a modulation signal to control the vibration of the electromagnet (C). The temperature rise of the electrode is detected by a thermocouple and used as a modulation signal.The PW is set so that when the temperature is high, the output pulse width is small and when the temperature is low, the pulse width is large.
(D) is when the vibration of the electromagnet is controlled by M modulation and output pulses, and as a comparative example (E) is when the electromagnet is excited and controlled by the voltage of a conventional discharge capacitor, and when the conventional electrode is rotated and applied to the workpiece. Assuming the contact method (F), the experimental f+n of machined surface roughness and processing speed were as shown in the table below.

Roughness μRmax Machining speed 11g/m1n (8 13
16 (B) H21 (C) 8 25 ([)
) G28(E)
23 8 (F)
12 As above 15, the conventional one (
E) Compared to (F), the products (A) to (D>) of the present invention have a surface roughness of about X and can increase the machining speed by about 2 to 3 times. The amount of transfer welding of the electrode material to the workpiece can be controlled because the vibration contact pressure, vibration amplitude, etc. can be adaptively controlled by controlling the pulse width of the vibration energy using PWM modulation depending on the temperature rise of the workpiece, etc. By being able to increase.

In addition, the signal to be detected, the pulse conditions of electromagnetic vibration, the percussion frequency, etc. are best selected depending on the coating material, workpiece material, etc., and the roughness and thickness of the intended coating layer. For example, it is convenient to store the conditions in a microcomputer or the like and perform selection control by automatic switching.

〔Effect of the invention〕

As described above, according to the present invention, a PWM modulation circuit is provided in the excitation power source for electric #1 vibration, and the S dynamic current whose pulse width is controlled is caused to flow through the electromagnetic vibration coil to control vibration.
1t of contact and separation between electrode and workpiece! Initial control can be arbitrarily and easily controlled, and signals that change depending on electrical discharge machining conditions such as gap voltage, current, discharge sound, light, heat, or temperature rise of the electrode and workpiece can be controlled arbitrarily and easily. By detecting this and using it as a PWM modulation signal, it is possible to optimally control the vibration according to the machining state.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional device, FIG. 2 is a main circuit diagram of an embodiment of the device of the present invention, and FIGS. 3 and 4 are partial structural diagrams of other embodiments of the present invention. 1... Workpiece 2... Electrode 3... Discharge capacitor 5... Electromagnet 6... ...... Coil 7 ...... PWM modulation circuit 8 ...... Vibration piece 9 ...... Magnetic body 10 ... ...Permanent magnet 12 ......Amplifier 51 ...... Electromagnet 61 ...... Coil patent applicant Inoue Japax Co., Ltd. Research Institute Representative Kiyoshi Inoue

Claims (2)

[Claims] (1) In a coating device that welds and coats the electrode material onto the workpiece by applying a pulse discharge to the gap between the electrodes while making contact and separation vibrations between the electrode and the workpiece, electromagnetic vibration is added to the contact and separation vibrations. 1. An electric discharge coating machining apparatus, comprising: an excitation power source for supplying vibration energy to the electromagnetic vibration device; and a PWM modulation circuit provided in the excitation power source. (2) The electric discharge coating processing apparatus according to claim 1, wherein a signal detected from the gap between the two is used as a modulation signal.