JPS60436Y2 - concrete formwork - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a copper concrete formwork using a single-sided stainless clad steel plate as a face plate.

Steel concrete formwork made of carbon steel is generally widely used, but the carbon steel plate used for the face plate has poor corrosion resistance, and the generated rust contaminates the concrete surface and has poor peelability from concrete. have shortcomings.

As one type of formwork that improves these drawbacks, a formwork using a stainless steel plate for the face plate has been proposed (Utility Model No. 53).
-47719).

This concrete formwork uses a stainless steel plate for the face plate, which not only increases the material cost, but also because the rib material other than the face plate is made of carbon steel, which improves weldability and reduces distortion due to welded joints. There was a problem with it.

First of all, since it is a welded joint between dissimilar metals, carbon steel and stainless steel, the elongation and impact properties of the joint are poor.
Welding defects are likely to occur, so to obtain a sound joint,
Special measures such as preheating and postheating are required during welding.

If this measure is neglected, there is a greater risk that the face plate and rib material will break at the joint during use.

Furthermore, the thermal conductivity of stainless steel is 40 to 60 that of carbon steel.
%, and the thermal expansion coefficient of austenitic stainless steel is about 50% larger than that of carbon steel, so the strain that occurs during welding is significantly larger than that of carbon steel.

Therefore, when the face plate is made of stainless steel, the amount of distortion of the face plate after welding is approximately 3% compared to that of a carbon steel face plate.
If the ratio of width to length of the formwork becomes 1:4 or less, the distortion becomes too large and it becomes difficult to manufacture the formwork.

The purpose of this invention is to solve the above-mentioned problems with concrete formwork that uses stainless steel plates and has excellent corrosion resistance.The purpose of this invention is to provide a high-quality concrete formwork that maintains corrosion resistance and has less distortion due to welded joints. This was done as a.

That is, the present invention provides a formwork in which a rib material made of carbon steel is welded to the back surface of a face plate of a clad steel plate of carbon steel and stainless steel, the stainless steel side of which is the outer surface, and the thickness of the stainless steel of the clad steel plate is This is a concrete formwork characterized by having a thickness of 0.05 mm or more and 25% or less of the total thickness of the clad steel plate.

FIG. 1 is a perspective view showing a concrete formwork according to the present invention. The stainless steel side of the face plate 1, which is made of a clad steel plate of carbon steel 1-1 and stainless steel 1-2, is the outer surface, and the carbon steel side of the back surface is the carbon steel side. It is constructed by joining steel rib members 2 by welding.

The thickness of the stainless steel clad steel plate used as the face plate in the concrete formwork of the present invention shown in FIG. 1 has an optimum range from the viewpoints of both corrosion resistance and the amount of distortion after welding.

That is, first of all, speaking of corrosion resistance, a steel plate (thickness 1
．． Figure 2 shows the results of conducting a salt water spray test between 48R and investigating the occurrence of pinholes on the stainless steel surface.

In Figure 2, Score 0; test sample No pinholes in all cases. Rating l; test sample Pinholes occur in less than 5% of the number of sheets. Score 2; test sample Pinholes occur in 5-10% of the number of sheets. Score 3; test sample Pinholes occur in more than 10% of the number of sheets. It is.

As can be seen from Figure 2, the thickness of stainless steel is 0.0
If it is 5 mm or more, no pinholes occur and good corrosion resistance is obtained.

Furthermore, almost similar results were obtained with other stainless steels such as 5US43R.

Next, we calculated the amount of distortion generated in the face plate after welding the stainless steel plate (
SUS430), various stainless steel (SUS430) clad steel sheets with different thicknesses of the stainless steel layer, and carbon steel sheets were investigated.

The results are shown in FIG.

The results shown in Figure 3 are formwork size: 300W x 15
001) (mm) standard type (Fig. 1) Face plate size: 2. Ot, X300W X 1500f
(rIr!IL) Rib material size: 2.6tX 55
W (mm) of concrete formwork, and the amount of distortion is indicated by the amount of warpage A in Fig. 4.

(In Fig. 4, 1 is the face plate, and the left and right direction in the drawing is the longitudinal direction (1
500rrr! rL), and 2 is a rib material with a width (height) of 55 mm.

) As can be seen from Figure 3, when the stainless steel layer thickness of a stainless clad steel plate is less than 25% of the total thickness of the clad steel plate, there is no significant difference from that of a carbon steel plate, and the amount of warpage is slight. On the other hand, when the thickness of the stainless steel layer reaches 40% of the total thickness, the amount of warpage becomes considerably large, and when it comes to stainless steel plates, the amount of warpage is extremely large, and with such products, it is impossible to correct or it is necessary to This makes a correction process essential.

For this reason, in the face plate of the stainless clad steel plate of the present invention, the thickness of the stainless steel layer must be 25% or less of the total thickness.

As mentioned above, the concrete formwork of the present invention has excellent corrosion resistance by using a stainless clad steel plate with a stainless steel layer thickness of 0.05 mm or more and 25% or less of the total thickness of the clad steel plate as the face plate. Moreover, it is possible to form a formwork with a very small amount of warpage after welding and joining.

In addition, in the concrete formwork of the present invention, since the back side of the face plate is made of carbon steel, the welding joints with rib materials, etc. are made of carbon steel, so welding between different metals such as stainless steel and carbon steel. It has superior weldability and welded joint properties, and is also cheaper in terms of welding costs.

As for the carbon steel that is the base material of the stainless steel clad steel sheet and the carbon steel that is used as the rib material, it is desirable to use low-carbon steel with excellent weldability, and it is also preferable to use steel with a small amount of alloying elements added for strength and other reasons. Low alloy steels can also be used;
The carbon steel of the present invention includes these as well.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the concrete formwork of the present invention, Fig. 2 is a diagram showing the relationship between the stainless steel layer thickness and pinhole occurrence rate of a stainless clad steel plate, and Fig. 3 is a perspective view showing the concrete formwork of the present invention. Stainless steel layer thickness ratio (relative to total thickness) and strain amount (of concrete formwork using steel plates)
FIG. 4 is a diagram showing a method for measuring the amount of warpage A. 1... Face plate, 1-1... Stainless steel m
, 1-2... Carbon steel, 2... Rib material.

Claims (1)

[Scope of utility model registration request] A formwork in which carbon steel rib material is custom-welded to the back carbon steel side of a face plate of a clad steel plate of carbon steel and stainless steel, with the stainless steel side facing outward, and the stainless steel thickness of the clad steel plate is 0. A concrete formwork characterized by having a thickness of .05 mm or more and 25% or less of the total thickness of the clad steel plate.