JPS63210204A - Manufacture of stainless clad aluminum strip - Google Patents

Abstract

PURPOSE:To efficiently obtain a stainless clad Al strip having superior workability by charging Al powder into a hopper formed with stainless steel strips, solidifying the Al powder confined in the space between the steel strips by pressing with rolling rolls and carrying out heating and rolling. CONSTITUTION:Al powder A is charged into a Y-shaped hopper formed with stainless steel strips S as shell materials, guide rolls G and rolling rolls M1. The strips S are continuously drawn and the Al powder confined in the space between the strips S is solidified by pressing and heated to a temp. close to the m.p. of Al with a heating furnace F. The resulting heated composite body is rolled with a pair of rolling rolls M2 to obtain a stainless clad Al strip. Since the rolling is carried out after heating to a temp. close to the m.p. of Al, the Al powder A is converted into a metallic Al sheet by heat generated during the rolling and the Al sheet bonds to the strips S with high bonding strength.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a manufacturing method for efficiently producing stainless steel clad aluminum strips with excellent workability, which have aluminum as the core material and stainless steel as the skin material. .

(Prior technology) Stainless steel clad aluminum strips, which are made of aluminum as the core material and stainless steel as the skin material, have the advantages of aluminum, such as being light and having good thermal conductivity, and the beautiful appearance of stainless steel, which has good corrosion resistance. Taking advantage of its advantages, it has been manufactured extensively until now, mainly for kitchen utensils.

Conventionally, stainless steel clad aluminum strips are produced by stacking a stainless steel strip S and an aluminum strip B, heating them in a heating furnace F, and rolling and joining them in a rolling mill M, as shown in Fig. 2. Although the strip plate 2 is being made,
It has the following problems. In other words, when using stainless steel clad aluminum plates as kitchen utensils, it is essential that the bonded surfaces do not peel off even when subjected to forming tests such as pressing, and even after repeated heating and cooling tests. , it is necessary that the bonding strength be sufficient to pass these tests. It is also necessary to be able to manufacture such stainless steel clad aluminum strips efficiently and at low cost. However, in the conventional manufacturing method, (a) bonding strength cannot be improved if an oxide film is attached to the surface, so it is necessary to grind both the mating surfaces of the stainless steel strip and aluminum strip in advance. Therefore, it is necessary to install a surface grinding device such as a rotating metal brush as seen in, for example, JP-A-58-173091.

(0) To prevent the formation of an oxide film during heating, an atmospheric heating furnace into which an inert gas is introduced may be used, but this increases operating costs. In order to reduce operating costs, an atmospheric heating furnace is better, but in that case, if the heating temperature is high, an oxide film will form on the mating surfaces of the stainless steel strip and aluminum strip, making it difficult to join them, and conversely, the heating temperature will be too high. If the temperature is too low, the diffusion rate of atoms at the bonding surface will be slow, making it difficult to bond.For these reasons, bonding rolling must be performed quickly within a limited temperature range.

(c) In order to break the oxide film generated during heating and expose the new surface to increase the bonding strength, it is necessary to roll at a high reduction rate of 20% or more. Therefore, as rolled, it becomes a work-hardened structure and has poor workability during press forming, so it is necessary to perform softening annealing after bond rolling, as shown in, for example, JP-A-55-15558 (1).

Due to these problems, it has not yet been possible to efficiently manufacture stainless steel clad aluminum strips with high bonding strength.

(Problems to be Solved by the Invention) The present invention solves the problems seen in the conventional method by forming the hopper part with a stainless steel strip serving as the skin material in the powder rolling method using aluminum powder. This method solves the problem and provides a technology for efficiently manufacturing stainless steel clad aluminum strips with excellent workability at low cost.

(Means for Solving the Problems) The so-called powder rolling method, in which thin plates are produced by directly rolling metal powder, has been used industrially for quite some time. For example, in the technique shown in Fig. 3, the metal powder A in the hopper H is continuously flowed out from a gap provided at the bottom of the hopper, and the metal powder is rolled and shaped by a pair of rolling rolls M provided in that area. The material is then heated and sintered in a heating furnace F, and then hot-rolled using rolling rolls M2 to form a thin plate, which is known as a general powder rolling method.

In the present invention, as shown in FIG. 1, two stainless steel strips S serving as skin materials are formed into a 7-shaped hopper via a guide roll G and a rolling roll M1, and are continuously fed. The aluminum powder A charged into the figure-7 hopper is passed through a pair of rolling rolls M arranged at the bottom of the figure-7 shape.
It flows out together with the stainless steel strip from the gap 1 at approximately the same speed as the stainless steel strip, but at that time, it is confined and compacted between the stainless steel strips. As a result, a composite body consisting of a core material in which the aluminum powder is almost solidified and a stainless steel strip (skin material) in close contact with the core material is formed. This composite, which has passed through rolling rolls M, is then heated in a heating furnace F to a temperature close to the melting point of aluminum. Although there are voids, macroscopically it is almost solid and in close contact with the stainless steel strip, so during heating,
A new oxide film rarely forms on the surface of the stainless steel strip that is in close contact with the aluminum powder.

The heated composite is then rolled by a pair of rolling rolls M2. In this case, since rolling is performed by heating to a temperature close to the melting point of aluminum, processing heat during rolling is added, and the aluminum powder becomes an aluminum metal plate and is bonded to the stainless steel strip with high bonding strength. Furthermore, according to experiments conducted by the present inventors, the rolling reduction ratio of the stainless steel strip at this time is 2z or less, so there is no need to perform softening annealing after rolling.

As described above, if the method of the present invention is used, problems such as grinding of the surface of an aluminum plate, reduction in work efficiency due to rolling at a limited temperature, and implementation of softening annealing after rolling can be avoided, as seen in conventional methods. This eliminates the problem and allows stainless clad aluminum strips to be manufactured efficiently and at low cost.

(Example) Soft annealed thickness 0. :1mm, width 900III11
The two Ni-based stainless steel sheet coils were attached to two uncoilers, unwound and passed through a guide roll and a rolling roll to form a figure-7 shape. Thereafter, aluminum powder was charged into the figure 7 shape. The roll gap of the rolling rolls was set to 4ml11, and the rolls were driven to draw the aluminum powder together with the stainless steel strip into the roll gap and compact the aluminum powder. Next, put it in the heating furnace 6
Immediately after heating it to 50°C and extracting it from the heating furnace, it was rolled to a thickness of 2.5 mm using rolling rolls for bonding to produce a stainless steel clad aluminum strip.

A sample was taken from the stainless steel clad aluminum strip manufactured by the above process, and a press molding test was conducted as a cooking pot. Water was also poured into the pot and a heating and cooling test was conducted. As a result, no peeling of the joint surface was observed. I couldn't see it at all.

(Effects of the Invention) By using the method of the present invention, stainless steel clad aluminum strips with excellent workability can be efficiently manufactured, thereby significantly reducing manufacturing costs.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the flow of each process when making a stainless steel clad aluminum strip using the method of the present invention, Figure 2 is a diagram showing a method for making a stainless steel clad aluminum strip using a conventional method, and Figure 3 is a diagram showing a method for making a stainless steel clad aluminum strip using the conventional method. A diagram showing a powder rolling method. S...Stainless steel strip, A...Aluminum powder,
B... Aluminum strip, M, M, M2... Roll, F... Heating furnace, H-... Hopper, Z... Stainless clad aluminum strip.

Claims (1)

[Claims] When combining aluminum powder and stainless steel strip using the powder rolling method, a Y-shaped hopper is formed using the stainless steel strip, aluminum powder is charged into the hopper, and the stainless steel strip and aluminum powder are combined. A method for producing a stainless steel clad aluminum strip, which comprises feeding aluminum powder between rolling rolls to compact the aluminum powder while surrounding it with a stainless steel strip, and then heating and rolling it.