JPH0558074B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention vibrates a rod-shaped covering material electrode disposed opposite to a workpiece at a predetermined amplitude in the axial direction of the electrode to open contact with the surface of the workpiece. While repeating the separation motion, intermittent voltage pulses are applied from the machining electrode between the electrode and the workpiece to generate electric discharge, and a relative distance between the two on a plane perpendicular to the axis of the electrode is generated. The present invention relates to a discharge coating method for coating a desired portion of a workpiece with the electrode material melted by discharge by applying a machining feed.

Conventional technology Conventionally, in this type of discharge coating, a coating material electrode is attached to a vibrating device, such as a vibrating device that is usually composed of an electromagnet and a repulsion spring, or a vibrating device that rotates a biased weight body having a rotational bias axis by a rotating stage. is attached to face the surface of the workpiece, and the electromagnet is excited by an oscillator, commercial alternating current, or discharge current or voltage of a discharge capacitor, so that it vibrates in the corresponding direction, and the tip of the coating electrode Repeat contact and release vibrations on the surface of the workpiece, and synchronize with the close contact to generate a pulse discharge in the gap, so that the molten part of the tip of the coating material electrode heated at the time of contact changes from the welded state to the workpiece and when the workpiece is separated. Welded to the surface of the workpiece,
The coating is performed by adhering and leaving the workpiece, and by performing relative scanning movement or scanning processing feed between the electrode and the workpiece in a direction approximately perpendicular to the vibration direction, the entire surface of the workpiece is covered. Alternatively, a discharge coating layer of a coating material constituting an electrode can be formed in a necessary portion.

Problems to be Solved by the Invention As described above, so-called electrical discharge coating is performed by simply touching and releasing the coating material electrode against the surface of the workpiece in the opposite direction using a vibrating motion as if tapping lightly. If the tip of the coating material electrode is melted by electric discharge and electricity, and the softened part melts and softened by electric discharge and electricity on the surface of the workpiece during light contact, a part of the surface of the workpiece will melt and weld to the softened part, and the electrode of the coating material will be pulled up and separated. Sometimes, the molten welded part breaks between the surface side of the workpiece and the tip of the coating material electrode, for example, at the tip of the electrode where the heat capacity is small, and the electrode material remains welded on the surface of the workpiece, resulting in coating. The cross section, ie, the coated surface, was a jagged surface with large irregularities, and the surface roughness of the coated surface was large, making it difficult to finish neatly. In addition, the surface of the workpiece becomes uneven due to the light contact and separation caused by the tip of the electrode, and the coating material does not adhere uniformly to the surface of the workpiece, making the coating surface uneven. There were many rather large holes and weak points rather than holes, and the amount and thickness of the coating was small, as well as the density of the coating layer.

Taking these points into consideration, the present inventors have previously determined that the axis of the contact/separation direction (coating material electrode By applying rotational motion around the central axis of the machine (or an eccentric axis that is eccentric from the central axis by an appropriate amount), the coated surface can be finished with a smooth and beautiful finish with little surface roughness, and the coating thickness can be increased. proposed a coating method in which the coating layer is denser, without holes or weak points, and the surface of the workpiece under the coating layer does not have to be too uneven. , or a mixture of these gases, equivalent gases, vapors, or even liquids, the coating material electrode is subjected to contact-release vibrational motion and rotational motion simultaneously to the workpiece. We proposed to perform electrical discharge coating processing. Furthermore, a coating method has been proposed which makes it possible to improve the surface roughness and increase the coating thickness by vibrating the coating material electrode with a minute amplitude in a direction perpendicular to the vibration direction of contact/separation.

In this way, when coating the workpiece by applying the coating electrode to the workpiece and performing vibration movements such as up and down in opposite directions, the melted portion of the tip of the coating electrode transfers to the surface of the workpiece upon contact, and at the same time, When pulling up the coating material electrode, the molten part breaks at the intermediate part between the workpiece side and the coating material electrode side, and the coating is performed.
Although the coating surface was not finished neatly due to the fractured surface, if the coating material electrode was rotated or vibrated with a small amplitude in the direction orthogonal to the vibration direction of the contact/release, the coating material electrode could be polished. Although the surface roughness of the coated surface is improved to some extent and the density of the coating layer is increased by moving the tip melting part on the surface of the drawn body while in contact with the drawn body, the condition is still not satisfactory. I can't say that.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide a highly dense coating process with even smaller surface roughness.

Means for Solving the Problems In order to achieve this object, the present invention provides a relative machining feed between a rod-shaped coating material electrode and a workpiece on a plane perpendicular to the axis of the electrode, so that the workpiece can be machined. In the electrical discharge coating method for coating a desired part of the body, rotation is applied to the electrode with the central axis in the axial direction, and the machining feed on the plane between the electrode and the workpiece is Another relative reciprocating movement, during which the electrode is in contact with the workpiece due to the contact/separation movement, the electrode is moved relative to the workpiece on the plane. It is characterized in that processing is performed while performing reciprocating movement that involves relative movement over a length of 1/2 or more of the diameter.

Function Conventionally, the rod-shaped covering material electrode was simply rotated or vibrated with a minute amplitude in a direction perpendicular to the direction of movement of the contact/separation, whereas in the present invention, the rotation of the electrode In addition to twisting the melted tip, the relative reciprocation on the plane allows the melted tip to be coated into the workpiece, resulting in an extremely smooth finished surface with low surface roughness. At the same time, a coating layer with high density and excellent compactness is formed. Furthermore, in the past, the reciprocating movement of the electrode on a plane perpendicular to the direction of movement of the contact and separation was only a vibration of minute amplitude, whereas in the present invention, the electrode is in contact with the workpiece. Due to the reciprocating movement in which the electrode relatively moves by a length of 1/2 or more of the diameter of the electrode on the plane during the period of time, the melted part of the tip can be applied to the surface of the workpiece. The effect of improving the density of the coating layer and improving the surface roughness of the finished surface becomes remarkable. This effect could not be clearly observed when the relative movement length of the electrode was less than 1/2 of the diameter of the electrode.

Embodiment FIG. 1 shows an embodiment of an apparatus for implementing the coating method of the present invention, in which a rod-shaped coating material electrode is subjected to axial vibration of contact and release with respect to the workpiece and rotational movement about the axis. 2 is a schematic diagram of a device for reciprocating a workpiece on a plane perpendicular to the axial direction of the electrode in the same embodiment, and FIG. 3 is a diagram of an electrical system in the same embodiment. The circuit connection diagram and FIG. 4 are waveform diagrams for explanation.

In the figure, 1 is a solid rod-shaped, short cylindrical, or pipe-shaped covering material electrode made of, for example, 10% Co (a little more due to the tungsten carbide binder) and the remainder WC sintered body. , 2 is a workpiece made of, for example, iron, which faces the electrode 1 and is connected to a processing power source 3 that applies intermittent voltage pulses between the two. Details of an embodiment of the machining power source 3 are shown in FIG. Reference numeral 4 denotes a support shaft having a support holder 4a for fixing the coating electrode 1, and is integrally connected to the shaft of the motor 5.

6 is the main body of the vibrating device, and the vibrating piece 6 is made of a spring material.
One end of a is fixed to enable elastic vibration, and the other end is a vibration free end, and the support shaft 4 is rotatably held by a ball bearing 8a at a connecting portion 8 provided at the free end. Further, 7 is an electromagnetic vibration device, and an excitation wire 7
A is given intermittent excitation at a predetermined frequency from a power source 9 to attract and release the iron piece 6b.

Thus, the coating electrode 1 is rotated by the motor 5 around an axis slightly offset from its central axis, for example, by 500~
Rotates at 1500r.pm and vibrates with vibration device 6
Electrical discharge coating is performed while contacting and separating the workpiece 2 by the vibration movement caused by the vibration.

The workpiece 2 is placed and fixed on a workbench 10 and is sequentially fed in the X and Y directions using motors M ₁ and M ₂ , that is, the workpiece 2 is fed for processing in order to cover the entire body or a desired portion.

Further, in the present invention, as shown in FIG. 4, if the period during which the coating material electrode 1 is in contact with the surface of the workpiece 2 due to vibration descent is designated as H, then during this period H, the coating material electrode 1 and the workpiece A relatively high-speed reciprocating movement is performed between the body 2 and the body 2 on a plane perpendicular to the opposing direction (vibration direction of the contact/separation). In order to provide movement in synchronization with H during this period, a spring 11 is used to apply bias tension in a certain direction to the processing table 10, which is supported so as to be able to slide in the left and right directions in the figure, and a movable iron piece 12 is attached to the other end. Electromagnet 13 installed and fixed to the machine frame
and facing each other with a predetermined gap therebetween.

Thus, when the electromagnet 13 is excited, the movable iron piece 1
2 is attracted to move the processing table 10 to the right in the figure, and when the electromagnet 13 is de-energized, the processing table 10 is moved left and right by the pulling force of the spiral 11. In addition, the movable iron piece 12 is arranged as a magnet with a polarity that repels the electromagnet 13, and the spring 11 presses the magnet (movable iron piece) 12 toward the electromagnet 13, so that when the electromagnet 13 is demagnetized, the processing table 10 is moved to the right. It may be moved back and forth so that it is located at the left side during excitation. Therefore, the excitation of the electromagnet 13 can be stopped at the timing when the charging current or the discharging current of the capacitor flows through the capacitor 14, as shown in the circuit diagram shown in FIG. 3, for example. A wire ring 13' of an electromagnet 13 is inserted in the position, and as the capacitor 14 is charged and discharged, the timing of pulse discharge between the coating material electrode 1 and the workpiece 2 and the time when the workpiece 2 moves are controlled. This will allow the two to be synchronized.

In this way, the workpiece 2 moves on the plane with respect to the coating material electrode 1 by the length that the processing table 10 moves, but the coating material electrode 1 that makes the contact/separation movement is processed. Period of contact with body 2 H
A movable iron piece 12 is moved so that the workpiece 2 (processing table 10) is moved by a length of 1/2 or more of the diameter of the electrode 1.
Gap length between and electromagnet 13, movable iron piece (magnet) 1
2 and the electromagnet 13 (magnetic repulsion),
Characteristics such as constants of the spring 11 are set.

On the other hand, in the electrode vibrating device 7, the power source 9 is a commercial AC power source with a frequency of 50 Hz (60 Hz), and if it is directly excited by this, the vibration rate will be 50 (60) times per second, or doubled by rectification for 1 second. 100 (120)
vibrations can be obtained, but the power supply 9 is set at 50 to 1000Hz.
It is also possible to use a pulse vibration power source that can be set as appropriate or selectively set. In addition, a circuit for operating the electromagnetic vibration device 7 is incorporated into the self-excited vibration circuit shown in FIG. 3, so that an exciting current flows through the vibration coil 7a when discharging between the coating material power supply 1 and the workpiece 2 or during charging. If the electromagnetic coil 13' is used in the same manner as the electromagnetic coil 13', the charging current will flow through the circuit after the capacitor is discharged, and the vibrating coil 7a
is excited and the iron piece 6b is attracted, and when it moves overcoming the spring force of the vibrating piece 6a, the covering material electrode 1 separates from the workpiece 2, and when the discharge period begins, the exciting current of the vibrating coil 7a decreases or cuts out. Vibration piece 6a
The covering material electrode 1 is pulled down by the spring force of .
The vibration of the coating electrode 1 and the reciprocating movement of the workpiece 2 are repeated, and in the case of the above self-excited vibration circuit, the frequency is approximately 300Hz, although it depends on the circuit constant.
It will be performed at ~600Hz. Furthermore, regarding the machining feed for scanning the desired coating area, the motors M ₁ and M ₂ do not move the workpiece 2 in the mutually orthogonal X and Y axis directions, but instead use rotational movement and radial movement. It is also possible to give a machining feed that is a combination of the following.

Conditions such as rotation, vibration, and movement of the coating electrode 1 and the workpiece 2 vary depending on the material combination of the coating electrode 1 and the workpiece 2 and the conditions of the coating discharge pulse. 1 is a rod-shaped electrode with a diameter of 5 mmφ made of WC-6% Co material, and workpiece 2 is a rod-shaped electrode made of WC-6% Co material.
S55C material, pulse width τON of discharge pulse: approximately 80μs,
When the pause width τOFF is approximately 20 μs and the discharge current width IP is approximately 60 A, the rotational speed of the electrode 1 is approximately 1000 rpm, and the vibration frequency of contact and release of the electrode 1 with respect to the workpiece 2 is approximately 300 Hz.
The scanning feed rate (scan processing feed rate) by motors M ₁ and M ₂ is approximately 3 of the cross-sectional diameter of one electrode per minute.
The horizontal vibration movement of the workpiece 2 by the electromagnet 13 etc. is set to about 7 times the length, and the vibration movement of the workpiece 2 in the horizontal direction by the electromagnet 13 etc. is preferably 2
It is desirable to set the vibration movement speed to ~3 times as high, and therefore, in the above case, it is desirable to set it to about 600 Hz or more. The vibration caused by the electromagnet 13 is limited to about 1000 Hz at most, although it depends on its vibration mechanism and the weight of the moving parts, which include the workpiece 2 and the processing table 10. It is generally easier to select a low opening frequency, for example, 50 to 120 Hz, and to perform movement at a high frequency, a well-known rotating cam or rotating crank should be used instead of the electromagnet 13 etc. Processing table 10 due to etc.
It is preferable to adopt a configuration in which the vibration is moved.

In addition, when using a capacitor charging/discharging circuit as shown in Fig. 3 as a covered discharge power source, the workpiece 2
Or, if the processing table 10 is small and light in weight, the vibration power supply 9 of the electrode 1 is a commercial AC half-wave or full-wave rectified excitation power supply, and the vibration-moving electromagnet 13 is used to charge the capacitor, for example, with its excitation wire. A connection configuration in which the magnet is inserted into a circuit and energized is preferable.

In the above case, the excitation wire ring can be inserted in series with the discharge circuit of the capacitor as described above, or the excitation wire ring can be connected in parallel between the capacitor terminals or the electrode workpiece. It is also possible to use a configuration in which the magnet is excited by a capacitor or a gap voltage.

Effects of the Invention As described above, according to the present invention, rotation about the central axis in the axial direction is applied to the rod-shaped coating material electrode that performs vibrational movements of contact and separation with respect to the workpiece facing in the axial direction. At the same time, during the period in which the electrode is in contact with the workpiece due to the contact/separation movement, the electrode is moved onto the workpiece on the plane where processing feed is performed, apart from normal processing feed. By performing a reciprocating movement in which the electrode is moved by a length of 1/2 or more of the diameter of the electrode, a finished surface with small surface roughness can be obtained, and the density of the coating layer can be reduced. It is possible to perform coating processing that is large and has excellent density.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of an apparatus for carrying out the coating method of the present invention, which applies contact/separation vibrations and rotational motion about the shaft center to a rod-shaped coating material electrode in the axial direction of the workpiece. 2 is a schematic diagram of a device for reciprocating a workpiece on a plane perpendicular to the axial direction of the electrode in the same embodiment, and FIG. 3 is a diagram of an electrical system in the same embodiment. The circuit connection diagram and FIG. 4 are waveform diagrams for explanation. In the figure, 1 is a coating material electrode, 2 is a workpiece, 3 is a power source, 4 is a support shaft, 5 is a motor, 6 is a vibrating device body, 6a is a vibrating body, 6b is an iron piece, 7 is an electromagnetic vibrating device, 9 10 is a vibration power supply, 10 is a processing table, 11 is a spring, 12 is a movable iron piece, and 13 is an electromagnet.

Claims (1)

[Claims] 1. A rod-shaped coating material electrode placed opposite the workpiece is vibrated in the axial direction of the electrode at a predetermined amplitude to repeatedly make contact and release movements with respect to the workpiece surface, and the electrode and the workpiece are Intermittent voltage pulses are applied from a machining power supply between the two to generate a discharge, and a relative machining feed on a plane perpendicular to the axis of the electrode is applied between the two, whereby the melted material is melted by the discharge. In the electrical discharge coating method of coating a desired part of a workpiece with the electrode material, rotation is applied to the electrode about an axial direction as a central axis, and the electrode material is placed on the plane between the electrode and the workpiece. A relative reciprocating movement that is different from the machining feed and moves the electrode relative to the workpiece on the plane during the period in which the electrode is in contact with the workpiece due to the contact/separation movement. A discharge coating method characterized in that processing is performed while performing reciprocating movement in which the electrode is relatively moved by a length of 1/2 or more of the diameter.