JPS60210381A - Joining method of different metallic bars - Google Patents

Abstract

PURPOSE:To improve the tensile strength of a welded part by drawing through the surface of the welded part from a metallic bar having higher toughness toward a metallic bar having lower toughness while the welded part is in the high-temp. state. CONSTITUTION:The metallic bar 1 having higher toughness is inserted into the hole 6 of a stationary die 7 which is the same in diameter while the welded part 3 is still in the high-temp. state after the press welding of the bars 1, 2 having different quality and the same diameter ends. The part 3 is drawn through the aperture end edge of the hole 6 in the direction opposite from the moving direction of the bars 1, 2 when the bar 2 is inserted into a guide hole held in proximity thereto and when impact force is applied to the end of the bar 2. The bars 1, 2 are pressurized and moved until flashes 4, 5 are successively removed and the part 3 is brought to the position where said part is inserted into the hole 6. The bar 2 having lower toughness is welded in the state of being enclosed by the bar 1 having higher toughness by which the tensile strength of the part 3 is remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for joining dissimilar metal rods, and particularly to a joining method in which a pair of dissimilar metal rods having the same diameter are welded together by high temperature pressure welding.

Such a joining method combines, for example, the exhaust pulp of an internal combustion engine with a metal rod on the valve body side made of Austenite I heat-resistant steel or nickel-based heat-resistant steel, and a wear-resistant alloy such as martensitic stainless steel or tool steel. The strength of the welded part is generally inferior to that of the matrix.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for joining dissimilar metal bars that can significantly improve the tensile strength of the welded portion.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. First, in FIG. 1, in order to form, for example, an exhaust pulp for an internal combustion engine, a metal rod 1 made of nickel-based heat-resistant steel, such as Inconel 751, and a martensitic A metal rod 2 made of stainless steel, for example 5UIII, is joined by the joining method of the present invention. That is, both metal rods 1 and 2 having the same diameter are welded to each other by high-temperature welding, such as friction welding, with their axes aligned, and the welded portion 3 is further squeezed while maintaining the high temperature.

In the welded part 3 of both metal rods 1 and 2, a burr 4 with a relatively small extension amount is formed over the entire circumference on the high toughness (-material side, that is, the metal rod 1 side), and a burr 4 with a relatively small extension amount is formed over the entire circumference, and on the welded part 3 of the two metal rods 1 and 2, A relatively thick burr 5 is formed over the entire circumference on the metal rod 2 side.These burrs 4 and 5 are removed by squeezing the welded portion 3.

In FIG. 2, in order to squeeze the welded portion 3, a mold 7 having a hole 6 with an inner diameter corresponding to the outer diameter of the metal rods 1 and 2 is prepared, and this mold I is fixed and placed. Further, a guide member 8 is arranged so as to be able to approach and move away from the mold 7, and a guide hole 9 through which the metal rod 2 can be inserted is bored in the guide member 8. Further, a punch rod 10 can be inserted into the guide hole 9 and can be applied with an impact force by a suppressing means (not shown).

After the friction welding of the metal rods 1 and 2 is completed, one of the metal rods 1 is inserted into the hole 6 of the mold 7 while the welded part 3 is still in a high temperature state. Next, by bringing the guide member 8 close to the mold 7, the other metal rod 2 is inserted into the guide hole 9 of the guide member 8. In this condition.

An impact force is applied to the end of the metal rod 2 in the guide hole 9 by the punch rod 10. As a result, both metal shells 1 and 2 are connected to the hole 6 of the mold 7.
However, since the mold 7 is fixed, the welded part 3 is attached to the metal rods 1 and 2 at the opening edge of the hole 6.
It will be squeezed in the opposite direction to the direction of movement.

As a result of this ironing, the burr 4 comes into contact with the end surface of the mold 7 as shown in FIG. 3, and cutting stress is generated in the burr 4 by the opening edge of the hole 6. Furthermore, by continuing the pressing force of the punch rod 10, the burrs 4 and 5 are sequentially cut off at the opening edge of the JL6. In this way, by moving the metal rods 1 and 2 under pressure to the position where the welded part 3 is inserted into the hole 6, the burrs 4 and 5 are completely removed from the welded part 3. The removed ring-shaped burrs 4 and 5 are transferred onto the punch rod 10, so by returning the punch rod 10 to its original position, the burrs 4 and 5 are transferred onto the punch rod 10 at the end surface of the guide member 8.
It will also be scraped off.

Since the welded portion 3 is squeezed in this manner, a tensile force is applied to the welded portion 3 in the squeezing direction 11, which increases as it goes radially outward from the center. Therefore, the welded part 12 of both metal rods 1 and 2 has a concave shape in which the material side with higher toughness, that is, the metal rod 1 side is recessed in the opposite direction to the ironing direction 11, and the side of the material with lower toughness, that is, the metal rod 2 side is recessed in the ironing direction. It has a convex shape that is convex in the opposite direction to 11.

In this way, the tensile strength of the welded portion 3 can be improved by forming a shape in which a material with low toughness is wrapped with a material with high toughness. For example, Inconel 75
Outer diameter 7.41nmφ consisting of 1 and 5UII11
When friction welding a pair of metal rods, the difference in tensile breaking load between when the welded part is squeezed and when it is not squeezed is shown in Figure 4. In this Figure 4,
Reference number A indicates when the welded part is squeezed, reference number B
This shows a case where the welded part was not squeezed, and it is clear that the tensile strength is significantly improved by squeezing the welded part.

As described above, according to the present invention, after a pair of metal rods of different types and the same diameter are welded to each other by high temperature pressure welding, when the welded portion is in a high temperature state, the metal rod with higher toughness may be By squeezing the surface of the welded part in the same way as the metal rod with lower toughness, the welded surfaces of both metal rods are made into a concave shape on the side of the metal rod with higher WJ property, and Since the metal rod side is formed into a convex shape, the weld 1nj is formed so as to wrap the material with low toughness with the material with high toughness, and the tensile strength can be significantly improved.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a partially cutaway side view showing friction welding, Fig. 2 is a vertical sectional side view of the main part showing when the banner is removed, and Fig. 3 is a side view of the main part when the banner is removed. FIG. 4 is a longitudinal cross-sectional side view showing the force applied to the welded part during removal; FIG. 1.2...Metal rod, 3.Welding part, 12...Welding surface 1st
Figure 2

Claims (1)

[Claims] After welding a pair of metal rods of different types and the same diameter to each other by high-temperature pressure welding, when the welded part is in a high temperature state, the metal rod with higher toughness is moved toward the metal rod with lower toughness. By squeezing the surface of the welded part with the metal rod, the welded surfaces of both metal rods are made into a concave shape on the metal rod side with higher toughness, and a convex shape on the metal rod side with lower toughness. A method for joining dissimilar metal bars.