JPS6363586A - Manufacture of clad strip - Google Patents

Abstract

PURPOSE:To pressure-weld a strip in the atmosphere and to continuously form a clad material by projecting a laser beam close to the apex of a strip approaching part by passing a dissimilar metal strip through rolls respectively, heating the trip surface rapidly and rolling it at the specific percentage reduction in thickness. CONSTITUTION:Dissimilar metal strips 1, 2 are overlapped at a roll bits inlet port 8, rolled by a rolling roll 5 and joined. A laser light 9 is projected on the metal strips 1, 2 of the roll bit inlet port 8 as a light flux Q. The light passing a point 10 repeats points 11-14 and the reflection, giving a strip energy at the reflection point. The energy giving is similarly performed on the other light in the light flux Q, the strip is rapidly heated and rolled immediately at the percentage reduction in thickness of more than 4%. The growth of the oxide film on the mating face of the strip is therefore restrained and a strong joining is obtainable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of continuously rolling and welding dissimilar metal strips in the atmosphere to continuously produce a cladding material for the strip.

(Prior Art) Conventionally, in manufacturing cladding materials by rolling and pressure welding, it has been considered most important to keep the mating surfaces clean and press weld. Taking this point into consideration, conventional techniques for producing crat materials are broadly divided into cut plates and strips. In the case of cut plates, it is possible to apply a method of vacuuming the mating surfaces, so it is possible to prevent oxidation of the joining interface and perform hot rolling welding. On the other hand, stripping is classified into cases where it is carried out in the atmosphere and cases where it is carried out in a vacuum or a non-oxidizing atmosphere. When bonding is performed in the atmosphere, heating oxidizes the mating surfaces and forms oxide scale on the bonding surfaces, making bonding difficult. Therefore, a method is used in which a large reduction rate is applied in the cold to generate a new surface on the joint surface and the joint is performed. FIG. 7 is a conceptual diagram showing this method, and shows a dissimilar metal strip 41.4 supplied from an uncoiler 43.
The two pinch rolls 44 are superimposed, and the rolling roll 4
5, they are rolled and joined under a large reduction ratio and wound up in a recoiler 46. However, the problem with this method is that the joining strength is weak and the metals that can be joined are limited to metals that are relatively easy to join, such as steel and A1, and because a large reduction is applied, the material changes due to work hardening, resulting in poor formability. Become.

Regarding the case in vacuum or in a non-oxidizing atmosphere, an example in vacuum is disclosed in Japanese Patent Publication No. 10202/1983. FIG. 8 shows an embodiment of this method, in which dissimilar metal strips 21.
30 are washed in the pickling chamber 22, 22', stacked on each other with pinch rolls 27, led to a vacuum chamber 23, welded both ends with an electron beam welder 24, heated in a vacuum heating furnace 25, and then rolled in a rolling machine in the atmosphere. 26 to roll and join. This method requires a vacuum chamber and a vacuum heating furnace, which increases equipment costs, and also requires management to ensure stable operation. Although this example is in a vacuum, similar problems exist in a non-oxidizing atmosphere.

(Problems to be Solved by the Invention) To summarize the above points again, the following problems exist when manufacturing a conventional metal strip cladding material. When joining in the atmosphere, cold rolling with a large reduction ratio or
Bond strength is weak. If the bonding is performed continuously in a vacuum or in a non-oxidizing atmosphere using a chamber, the equipment will be severely damaged and the cost will be high.

The present invention solves the above-mentioned drawbacks of the conventional method, and the present invention provides a strip crut that significantly reduces oxidation when heating the bonding interface in the atmosphere, and improves the bonding strength of the interface with fewer rolling blades than cold bonding. This paper presents a method for continuously manufacturing .

(Means for solving problems) The present invention embodies the following ideas.

A strong joint is achieved by simultaneously incorporating the advantages that the mating surfaces are not heated during cold rolling, so oxidation does not proceed, and that the mating surfaces are heated during hot rolling, making them active for joining. get. The key to this is to establish a heating method that minimizes oxidation in the atmosphere.

Therefore, if the bonding interface is heated rapidly in a short period of time, the degree of oxidation will be small even if the bonding interface is raised to a fairly high temperature.This may be due to the effect of activating the bonding interface at a high temperature, or it will sufficiently compensate for the disadvantageous effects of oxidation. I focused on what was likely to happen. In order to embody this idea, it was confirmed through experiments that lasers could be used, and the present invention was completed.

That is, the gist of the present invention is to provide a method for continuously obtaining a cladding material by press-welding dissimilar metal strips between a pair of rolls, in which each of the dissimilar metal strips is directed between the pair of rolls in the atmosphere. Asymptotically, the dissimilar metal strip is passed between the pair of rolls, and a laser beam is irradiated toward the vicinity of the apex of the patterned inner surface of the asymptotic part of the wedge-shaped strip with the apex between the pair of rolls. The surface of each metal strip is rapidly heated near the inlet to a temperature range lower than the melting point of any of the metals in the strip-shaped dissimilar metal, and immediately rolling (stretching) is applied to apply a rolling reduction of 4% or more to form the dissimilar metal strip. This is a method for manufacturing clad strips, characterized in that they are joined together continuously.

The present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, the metal strips 1.2 to be joined are each supplied from an uncoiler 3,
The sheets are passed through and overlapped by a rolling roll 5, rolled at the same time, and wound up by a recoiler 6. metal strip 1,
2 are rolled and joined by a rolling roll 5, and in order to facilitate this process, a laser beam from a laser head 7 is irradiated onto a wedge-shaped strip near the roll bite entrance of the rolling roll 5 to heat the mating surfaces. The rolling reduction rate of the rolling roll 5 is r, and the thickness of the metal strip 1.2 before rolling is hl, h2. Crut plate thickness after rolling. ut
Then, as a condition for obtaining good bonding, the rolling reduction ratio r of the following equation is required.

r≧0.04 r − (h T − h out ) / h Th ′
r = h□+h2 However, a seemingly similar method of continuously joining metals using a laser in the atmosphere was published in Japanese Patent Publication No. 59-2326.
76. FIG. 9 shows an example in which this method is applied to welding an electric resistance welded pipe. The abutting portion 32 is irradiated by a heating device (not shown) and a laser oscillator (not shown), and is heated to a temperature above the melting point by a laser beam 33 directed toward the abutting portion 22, and then pressure welded by a squeeze roll 34. Ru.

However, since this method involves melting metal, it is completely different from the present invention and cannot be used for manufacturing clad strips. After all, joining is performed by squeezing out the molten metal and slack at the abutting portion outside of the mating surfaces during crimping, and making use of the new surface that is created on the mating surfaces. This squeezing of the molten metal and slack takes place in the thickness direction of the plate in a steady state. In the present invention, if the strip is heated above its melting point, the molten metal must be squeezed out in the width direction of the strip in a steady state. This is because if the molten metal is not squeezed out in the width direction of the plate, it will accumulate at the apex of the wedge and a steady state will not be achieved. However, in the case of the strip that is the subject of the present invention, steady squeezing in the width direction of the plate is extremely difficult due to the long distance in the width direction, and it is impossible to perform fusion bonding. The method is completely different from the method shown in FIG.

(Action of the invention) Next, the action and operation of the invention will be explained. FIG. 2 is a sectional view perpendicular to the central axis of the roll showing the vicinity of the roll bite inlet. The dissimilar metal strips 1.2 are superimposed on each other in a roll hide layer 8 and are rolled and joined by a rolling roll 5. The laser beam 9 is directed from a laser head (not shown) to the roll bite inlet 8 as a convergent beam with an intensity distribution specific to its final optical system and strikes the metal strip 1.
．． 2 and passes through point 10, for example, the ray passes through point 11.1
2, 13. As shown in 14, the number of geometrical reflections until the light beam is repeatedly reflected by the metal strip and directed toward the racer head is given by α (deg), which is the angle formed by the metal strips 1 and 2. It is approximately given by N = 180/α.

If the intensity of the incident ray is q, -t at any reflection point i of points 11.12, 13.14, the intensity of the reflected ray is qi, and the reflectance of point i is, then the reflection point i is the metal strip. The energy W given to is given by the following equation.

W□=q+-+ -(1= (+ to 1-) q;-+
Other light rays passing through each point of the cross section perpendicular to the progress of the light beam are similarly reflected, and energy is imparted to the plate. The energy W imparted to the plate by the convergent light beam has a density distribution in the rolling direction on the mating surface of the metal strip 1.2. The metal strips 1 and 2 are fed at speeds V□ and V2, respectively, and receive energy from the convergent beam near the roll bite entrance according to the applied energy density distribution, and are heated as the strips advance.

Next, an example of temperature simulation using the heat transfer model under the conditions shown in Table 1 is shown in FIGS. 3 and 4. In Figure 3, the horizontal axis shows the coordinate X in the feeding direction, and the vertical axis shows the temperature T of the metal strip.
After moving through a section of = Omm for about 2 seconds, a rapid heating condition of about 7000°C/sec is obtained near the roll bite inlet. Extremely short heating time is possible. In FIG. 4, the horizontal axis shows the coordinate y in the plate thickness direction, and the vertical axis shows the temperature T of the metal strip, and the temperature distribution in the plate thickness direction is maximized at the mating surface. Furthermore, it goes without saying that by increasing the laser output and feed rate, the temperature increase rate and the temperature gradient in the thickness direction can be increased.

Table 1 According to the above results, according to the present invention, rolling can shorten the time during which surface oxidation occurs before the mating surfaces are joined, that is, the time during which the mating surfaces are exposed to high temperature in the atmosphere, thereby reducing the amount of time that is harmful to joining. This suppresses the growth of oxide film on the mating surfaces.

Furthermore, since the temperature gradient in the thickness direction of the plates is increased, it is possible to minimize the amount of heat input into the metal strips required for bonding, which has the effect of suppressing thermal effects on the material.

As described above, according to the method of the present invention, there is almost no oxidation, so there is no need for slag to prevent oxidation as in welding, and furthermore, the heating by the laser beam is clean and does not melt the metal. , it is possible to suppress the occurrence of defects on the bonding surface and obtain strong bonding properties.

The present invention not only keeps the mating surfaces clean during heating, but also
The strips are stretched by rolling with two wooden rolls, and an active surface, that is, a new surface, is actively generated on the mating surfaces to facilitate joining. Heating with a laser beam reduces the deformation resistance of the mating surfaces, making it easier to generate new surfaces, resulting in strong bonding strength. The present invention is characterized by organically using a heating method using a laser beam and a bonding method by rolling, and if either one of them is lacking, a good bond cannot be obtained.

(Example) One embodiment of the present invention is shown using FIG.

An uncoiler 3, guide roll 4, pinch roll (39 mmφ) 5, and recoiler 6 are placed on a common stand (not shown).
is located. A coil of dissimilar metal strips 1.2 is attached to an uncoiler 3, passes through a guide roll 4 as shown in the figure, is overlapped by a pinch roll 5, is rolled by a non-driven pinch roll 5, and is wound up by a recoiler 6. . The recoiler 6 is driven by a variable rotation speed, and the uncoiler 3 has a brake that can be adjusted manually, and the tension of the strip is set by adjusting the brake. The pinch rolls 5 can maintain a constant rolling edge regardless of changes in plate thickness during rolling. The laser is extracted from a 14Kw CO2 laser oscillator (not shown) as a convergent beam from the laser head 7 using an integration mirror with a focal length of 860 mm as the final optical system, and is focused to a thickness of approximately 15 mm at the entrance of the roll bite. It was placed in In the experiment, the width of the laser beam was also 15m+m.
This is because the width to be joined must be sized according to the board width.

The implementation details are shown in Table 2. Two types of combinations of crat metals were used: (I) SO3430 and mild steel, and (II) mild steel (A) and mild steel (B) with different component systems. (I
) The results for case (II) are shown in FIG. 5, and the results for case (II) are shown in FIG. In each figure, open marks indicate those that were joined, and filled marks indicate those that were not joined. It can be seen from both figures that rolling (stretching) is necessary to obtain the bond. The lower limit of the rolling reduction required for bonding is not necessarily clear, or data indicating good bonding with a rolling reduction of 4z or less was not obtained.

In addition, the larger the amount of heat input, the better if the temperature of the material is kept below the melting point, and the higher the interface temperature, the better the bonding will be. However, the lower limit of this heat input depends on the metal combination and thickness. In addition, the faster the material speed, the less oxidation occurs, which tends to be better, but this also depends on the combination of metals and the desired temperature of the bonding interface.

Table 2 As a result of microstructural observation of a cross section perpendicular to the longitudinal direction of the clad strip after good bonding, no microstructure indicating metal melting was found on the bonded surface. In the strips that were not joined by rolling, the mating surfaces were exposed to the atmosphere, resulting in discoloration due to oxidation, whereas the separated surfaces in the joint strength test after joining retained the same metallic luster as before heating. This fully demonstrates the feature of the method of the present invention that no oxidation occurs.

(Effects of the Invention) As explained above, according to the present invention, it is possible to continuously manufacture different types of strips of crat material in the atmosphere efficiently and without any deterioration in material quality. Therefore, its industrial value is extremely large.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the strip cladding material manufacturing equipment for carrying out the method of the present invention, Fig. 2 is a detailed explanatory diagram of the cladding part for the operation of the present invention, and Figs. 3 and 4 are heat transfer models. FIGS. 5 and 6 are graphs showing an example of temperature simulation using the present invention. FIG. 7, FIG. 8, and FIG. 9 are explanatory diagrams of conventional examples. 1.2...Metal strip, 3...Uncoiler-1
4...Guide roll, 5...Rolling roll, 6...
Recoiler, 7... Laser head, 8... Roll bite inlet, 9... Laser beam.

Claims (1)

[Claims] In a method for continuously obtaining a cladding material by pressing dissimilar metal strips between a pair of rolls, the dissimilar metal strips are brought into contact with each other in a pair of rolls such that each of the dissimilar metal strips approaches the pair of rolls in the atmosphere. At the same time, a laser beam is directed toward the vicinity of the apex of the wedge-shaped inner surface of the wedge-shaped strip asymptotic portion having the apex between the roll pairs, and the laser beam is directed toward the vicinity of the apex of the wedge-shaped inner surface of the wedge-shaped strip asymptotic portion having the apex between the roll pairs. The dissimilar metal strips are continuously joined by rapidly heating the surface of each metal strip to a temperature range lower than the melting point of the metal strip and immediately rolling (stretching) applying a rolling reduction of 4% or more. Features: Manufacturing method of clad strip.