JPS59137188A - Ultrasonic welding method - Google Patents

Abstract

PURPOSE:To prevent formation of flash and to accomplish stably joining with high accuracy by forming the one friction area of joining materials smaller than the other friction area and subjecting the materials to ultrasonic welding. CONSTITUTION:Many pieces of ruggedness are provided by pressing, etc. on the surface to be joined of a joining material 8 which is harder or has a higher softening point than a joining material 7. The material 8 is fixed on an anvil 6, and the material 7 is superposed on the surface to be joined, then load is exerted thereon in the direction of an arrow 9. The high frequency current generated from an ultrasonic oscillator 1 is coverted to ultrasonic oscillation by an oscillator 2 and the oscillation is induced in the direction of an arrow 5 in a tip 4 via a horn 3 thereby subjecting the materials 7, 8 to friction press welding. The peak 8a in the projecting part on the top surface of the material 8 slides in contact with the material 7 and generates high heat. Said point is softened by said heat and the material 7 is softened as well as its temp. rises. The softened material flows into the space 10 in the recess thus forming the stable and secure joint surface along the rugged surface with good thermal efficiency without generating any flash.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a technique that makes it possible to improve the reliability of ultrasonic welding and expand the range of applicable materials.

[Technical background of the invention and its problems]

Ultrasonic welding is one of the methods for joining metal materials and the like. The conventional method will be explained with reference to the configuration diagram of a welding device shown in FIG. The joint material 7 and 8 are sandwiched between the tip 4 and the anvil 6, a load is applied in the direction of the arrow 9, and friction welding is performed using ultrasonic vibration. If relative slippage is prevented between the bonding material 7 and the step 4 and between the bonding material F18 and the anvil 6, frictional heat generation will occur between the bonding materials 7 and 8. Due to this heat generation, the bonding materials 7 and 8 will Localized high temperatures make it easier for plastic flow of the material to occur, as well as interdiffusion of metal atoms, resulting in solid-phase bonding between the bonding materials.One of the important requirements that influences the bonding state at this time. As such, there is a pressure between the bonding materials 7 and 8.

If this pressure is too small, it will be difficult to bond the entire surface of the contact area between the bonding materials 7 and 8, and the bonding strength will vary greatly. To obtain full-surface bonding, it is necessary to increase the mutual surface pressure. However, when the blood pressure is increased, the wear of the contact surface is large due to the temperature rise due to friction at the joint surface of the joint material 7, and the leakage (around the joint material 7) is increased, resulting in loss of the material itself. In addition, deburring work, etc. is required, which poses an obstacle in actual use. Furthermore, if the hardness or softening temperature of the bonding materials differs, a phenomenon occurs in which the cracks are larger than those of the softer bonding materials. Furthermore, if the welding material becomes larger, the excitation force will increase in order to maintain the necessary surface pressure (2), and of course the capacity of the vibrator 2 (2) will limit the size of the material that can be welded. Ta.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned considerations (2) and aims to provide ultrasonic welding dimensions that do not require ν convergence and have less variation in bonding strength.

[Summary of the invention]

When welding materials by applying ultrasonic vibration and pressure,
In order to make the contact area smaller than the other surface on the surface of the joining material, which has a higher hardness or a higher softening temperature, unevenness is formed to increase the surface pressure during welding and increase welding efficiency to the high y resistance contact area. Ultrasonic welding method that does not generate paris.

[Embodiments of the invention]

The present invention will be explained with reference to the drawings of one embodiment.

Fig. 2 is an enlarged cross-sectional view of the main part of the weld, and shows the surface to be joined of a material 8 which is harder than the joining material 7 or has a higher softening point (= many irregularities are provided. From the viewpoint of workability, these irregularities are formed by press working. Good. The pitch of the unevenness and the height from the bottom 8b of the concave part to the apex 8a of the convex part or the space 1 surrounded by the adjacent convex parts
The specifications of the unevenness, such as the size of the 0 and the size of the apex 8a of the convex portion, are not limited, but are determined by taking into consideration the expected bonding strength, stability of variation, and amount of paris.

Next, the welding process of the present invention will be explained. Pressurize the chip 4,
When the horn 3 starts to vibrate due to ultrasonic input, the apexes 8a of the convex portions of the bonding material 7 and the bonding material 8 begin to rub, and the contact portion generates heat. The steeper this heat generation phenomenon is, the less time there is for heat dissipation, and the temperature rise at the contact portion is localized and at the same time becomes higher.

Therefore, since the bonding material 7 and the bonding material 8 are in contact with each other only through a small contact area of the apex 8a, the ultrasonic energy transmitted by the horn 3 is input to the contact surface of the bonding material 7 corresponding to the apex 8a of the bonding material 8. The heat density is greater than in the past, and heat generation is concentrated in the small contact area, and the temperature of the opposing sliding contact area between the apex 8a and the bonding material 7 rises more rapidly than in the past, reaching a higher temperature. At this time, the vertex 8a of the joining material 8
becomes hotter than the friction part of the bonding material 7, and the bonding material $4
7 as well as the bonding material 8, which has a higher softening point, also softens at the apex 8a. As the ultrasonic excitation input continues, the convex portion of the bonding material 8 rapidly softens from the apex 8a, and the bonding member 7 and the bonding material 8 are bonded. At this time, the bonding material 7, which has a softening point lower than that of the bonding material 8, flows into the valleys of the bonding material 8 and forms a bond along the unevenness of the bonding material 8.In the uneven bonding, the bonding interface is different from the conventional planar boundary. Since it is larger than the surface, a large absolute value of strength can be obtained.The temperature rise of the entire material is small due to high thermal efficiency.The amount of compression of the material is smaller than before.Bonding materials with a low softening point have a high softening point. The welding material flows into the concave part of the welding material 4 and has the advantage that the amount flowing out outside the joint is relatively smaller than that of the conventional method.Also, it has good thermal efficiency, so if the welding equipment is the same and the material is the same, It is possible to weld a larger contact area by the amplifier of thermal efficiency, and it is possible to weld thick plates.Also, if the size of the welding material is the same, it is possible to weld materials that require a higher temperature.

In addition, as other modified examples, FIG. 3 shows the unevenness in a ring shape, and FIG.

〔Effect of the invention〕

As described above, according to the present invention, it is now possible to easily join materials with different hardnesses, which has been difficult in the past, and it is also possible to perform welding with less flash. It also has the effect of expanding the capabilities of ultrasonic welding equipment.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a conventional ultrasonic welding device, Fig. 2 is an enlarged cross-sectional view of the main welding part showing one embodiment of the present invention, and Figs. 3 and 4 show other modifications of the present invention. FIG. 3 is a plan view of a protrusion. 1... Ultrasonic oscillator 2... Vibrator 3... Horn 4... Step 5... Vibration direction
6...Anvil 7.8...Joining material 8
a...Apex of the recess 8b...Bottom of the protrusion 9.
...Pressure direction 10...Space.

Claims (2)

[Claims] (1) An ultrasonic welding method characterized in that when joining is performed by local heat generation between the joining materials by exciting ultrasonic vibrations in the joining materials, the friction area of one side of the joining materials is made smaller than the friction area of the other. . (2) The ultrasonic welding method according to claim 1, wherein the friction area is adjusted to be smaller on the friction surface of the joining material on the side where the softening temperature of the joining material is higher or the side where the joining material is higher in hardness.