JPH0256315B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for joining ceramics by pulsed energization.

[Prior Art] FIG. 2 is a schematic diagram showing an electrical bonding device for ceramics prior to the present invention. For example, when non-conductive ceramics are to be bonded, there is a After interposing an adhesive 3 that is conductive at high temperatures, the joint is heated with gas flames 6 and 7 generated from the tips of blowpipe electrodes 4 and 5 (hereinafter simply referred to as blowpipe) installed on both sides of the joint. At the same time, a DC or AC voltage of 1,000 to 10,000 V is applied between the blowpipe 4 and 5. The power supply device 8 may be one having a no-load voltage of about 1000 to 10000V. Although the output current is not constant depending on the area of the joint, etc., it is sufficient to supply a small current of about several amperes or less.

The ceramics at the joint heated to a high temperature by the gas flames 6 and 7 become highly conductive, and the blowpipe 4 and 5
The electric charge carried by the gas flames 6, 7 from the two electrodes passes through the ceramics of the joint, and current is passed between the two electrodes. At this time, the bonded portion is heated in a short time by resistance heat generated in the ceramics, that is, joule heat, and the ceramics are welded to each other and firmly bonded. When the joint is rapidly heated by Joule heat, the electrical resistance value decreases significantly and the conductivity rapidly increases. For this reason, an output current control circuit 9 is required to maintain the current at an appropriate value. Since the appropriate current value varies depending on the type of ceramics used, it may be determined as appropriate depending on these types.

FIG. 3 is a diagram showing an energization pattern before the present invention, in which the horizontal axis represents the elapsed bonding time T, and the vertical axis represents the energizing current value I at each position of the joint and between each position.

In the joining method before the present invention, for example, the blowpipe 4, 5 was stopped at the joining start position P1 shown in FIG. 2, and the current value I1 was enough to melt the joint between times T1 and T2. Apply current and move to the welding start position P1
After the point is melted, for example, the blowpipe 4 and 5 are moved from point P1 to point P2 and P3 by a moving device (not shown).
A current value I1 was applied while moving continuously from point to point. In this way, the joining method before the present invention was
The idea was to continuously supply a preset current value while moving the blowpipe at a substantially constant speed.

[Problems to be Solved by the Invention] However, in the methods used before the present invention, there was a risk that the joint would become discontinuous if the joint was long.

The reasons for the occurrence of discontinuous points in the joint section will be explained below.

The blowpipe facing the ceramics is continuously
Consider the case of moving from point P1 to point P2 and point P3 shown in the figure. Assume that the blowpipe is now at point P1 and current is being applied at point P1. Next, even if the blowpipe is moved to point P2, the energized position still remains at point P1, the melting point of the joint, and when the blowpipe reaches point P3 after some time has passed, the energized position suddenly changes. It jumps from P1 point to P3 point. As a result, a joint failure occurs between point P1 and point P3. This phenomenon in which the current-carrying part tends to remain in its original position even when the blowpipe moves continuously is due to the fact that the electrical resistance value of the joint part has a negative temperature characteristic. In other words, even if the blowpipe reaches point P2, the temperature will be lower than point P1 than point P2.
This is because the resistance value is smaller in the energizing path 4-P1-5 than in 4-P2-5 because the point is higher, and current flows more easily.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, the relative movement of the ceramic and the blowpipe electrode in the joining direction is stopped for a preset time, or this movement is performed at a low speed. There is a period in which the ceramic joint is melted by applying a high current by applying a direct current or alternating current voltage while relatively moving, and after that period, the above-mentioned voltage is applied while relatively moving by a preset distance. The ceramic bonding method is characterized by repeating a period in which a low current is applied or the current is stopped to cool the ceramic bonded portion.

[Function] For example, with the blowpipe stopped or moved at low speed in the welding direction, the joint can be melted for an appropriate time preset according to the material, size, shape, etc. of the ceramics. After applying a high current, for example, the blowpipe is moved in the welding direction by an appropriate distance preset depending on the type of ceramics. The current value at this time is set to zero or to a current value smaller than the current that melts the joint. Next, after moving the above-mentioned appropriate distance, the blowpipe is again stopped or moved at a low speed, and a high current capable of melting the joint is applied for an appropriate period of time. Continuing,
The blowpipe is moved in the joining direction again using the above-mentioned current value. In this way, bonding is achieved by repeating a period in which a high current is applied to melt the ceramic joint, and a period in which the current is cut off or a low current is applied to cool the joint. When the portion is long, it is possible to obtain a good joint without discontinuity.

[Example] FIG. 1A is a diagram showing the energization pattern of the first example of the present invention, in which the horizontal and vertical axes represent the third
Similarly to the figure, the bonding elapsed time T, each position of the bonded portion, and the energizing current I at each position are shown.

Now, move the blowpipe 4 and 5 to the starting position shown in Figure 2.
The robot is stopped at point P1, and a high current I1 that can melt the joint is applied between time T1 and T2, that is, for a preset time depending on the ceramic material, size, shape, etc. Starting position P1
After the point is melted, for example, the blowpipe 4, 5 is moved from point P1 to point P2 by a moving device (not shown) by a preset distance depending on the material, size, shape, etc. of the ceramic between time T2 and T3. move it. During this movement, the current value is set to zero. Therefore, during this period of movement, electricity is not supplied, so
Point P1 and its vicinity are gradually cooled, and the electrical resistance value of this part gradually increases accordingly.

Next, when the blowpipe 4 and 5 are stopped at point P2 and a high current of current value I1 is applied again between time T3 and T4, the electrical resistance value at point P1 and its vicinity has already increased as described above. Therefore, the energization path when reenergizing is not limited to 4-P1-5.
4-Move to P2-5. The energization at this point P2 is controlled in the same way as the case at point P1 described above, so that a joint is formed at and near point P2, and a substantially continuous joint is formed from point P1 to point P2. Ru. By repeating this process, the entire ceramics 1 and 2 can be bonded continuously.

In the experimental example, when joining silicon nitride ceramics (thickness 17 mm), with the blowpipe stopped, 0.5A is applied for 6 seconds, and then the blowpipe is moved the same distance as the tip diameter (2 mm). By repeating the conditions, a satisfactory continuous joint could be formed.

FIG. 1B is a diagram showing the energization pattern of the second embodiment of the present invention, and the differences from FIG. 1A are as follows.
For example, within the period of moving the blowpipe 4, 5,
A low current value I2 smaller than a high current value I1 capable of melting the joint is applied, for example, I2=I1/10. The other parts are completely the same as those in FIG. 1A, so the explanation will be omitted. Therefore, the temperature change at the bonding portion becomes more gradual than in the experimental example of the first embodiment, and the strain during bonding can be reduced.

FIG. 1C is a diagram showing the energization pattern of the third embodiment of the present invention, and the difference from FIG. The current is applied by up slope control until the high current value I1 is reached.
Thereafter, a period of energization with a high current value I1 is provided, and finally energization is performed by down slope control. The other parts are completely the same as those in FIGS. 1A and 1B, so the explanation will be omitted. Therefore, since the temperature change at the bonding portion becomes more gradual than in the experimental examples according to the first and second embodiments, the strain during bonding can be further reduced.

In the above explanation, P1 point, P2 point, P3 point, etc.
The movement of the blowpipe was stopped, but instead of being stopped,
You may move around that area at a low speed.

Further, although the blowpipe is moved in the joining direction, the ceramic may also be moved.In short, the blowpipe and the ceramic may be moved relative to each other.

[Effects of the Invention] According to the present invention, a continuous joint can be obtained without causing a joint failure due to discontinuity in the ceramic joint.

According to the present invention, it is possible to reduce distortion at the joint.

According to the present invention, it is possible to improve the reinforcing strength and reduce its variation.

According to the present invention, the aesthetic appearance of the joint can be improved.

[Brief explanation of drawings]

FIG. 1A is a diagram showing the energization pattern of the first embodiment of the present invention, FIG. 1B is a diagram showing the energization pattern of the second embodiment of the invention, and FIG.
FIG. 2 is a schematic diagram showing an electric bonding device for ceramics prior to the present invention, and FIG. 3 is a diagram showing a current conduction pattern prior to the present invention. 1, 2...Ceramics, 3...Adhesive, 4,
5... Blowpipe electrode, 6, 7... Gas flame, 8... Power supply device, 9... Output current control circuit.

Claims (1)

[Claims] 1. Ceramics that are conductive at high temperatures are butted together, or ceramics are butted together with an adhesive that is conductive at high temperatures, and at least one pair of blowpipe electrodes are placed on both sides of the joint, and a combustible gas ejection hole is installed. A method of bonding by installing ceramics facing a joint part, heating the joint part with a gas flame from the blowpipe electrode, and applying a heating current between the blowpipe electrodes by applying a heating current. a period in which the relative movement of the ceramic and the blowpipe electrode in the bonding direction is stopped for a period of time, or a high current is applied as the current while the relative movement is caused at a low speed to melt the bonded portion, and the period elapses. A pulse current bonding method for ceramics, in which the ceramics are bonded by repeating a period in which the current is subsequently cut off or a low current is applied to cool the bonded portion while the relative movement is performed by a preset distance.