FR2462700A1 - Barrier for mould for taking samples of molten metal - has metal screen protecting mould inlet with cardboard liner - Google Patents

Abstract

A supporting screen of cardboard is provided between the metal screen which protects the inlet channel to the mould and the mould carrier in a device for taking a sample of molten metal. The metal screen is dish-shaped or alternatively it may be a disc fitting into a recess in the end of the mould carrier. Pref. the screen is of steel about 0.2 mm thick. The supporting screen is a disc of cardboard. Used to make possible the taking of a sample of molten iron or steel, without the penetration of slag either into the sample mould or below the surface of the bath. At the same time, the cost of the mould and its protective covers which are used only once, is reduced considerably. The sample itself is also improved, esp. as regards its porosity.

Description

Improved device for taking samples of molten metals.

 The present invention relates to an improved device for taking samples of molten metals, such as cast iron and steel.

Sampling of this kind has been carried out for many years with devices comprising a sampling container mounted in a support of a refractory material, the assembly thus formed being slid in the manner of a plug into the end of a support tube, disposed in turn on the end of a lance with which the sampling device concerned is immersed in the molten metal bath from which one wishes to take samples.

 Sampling devices of the kind defined above are described for example in Belgian patents No. 824,467, No. 831,499 and No. 866,511.

To avoid any penetration of slag into said sampling container of the devices in question, a metal cap is provided on the support, which is destroyed by fusion during immersion in the bath of molten metal. This metal cap is generally covered with a cardboard cap to avoid the adhesion of slag by solidification to the metal cap, which would thus be entrained in the bath. This risk arises especially in molten metal baths whose temperature is close to the solidification point.

 This known system with a metallic cap and a cardboard protective cap is however not very economical, since the sampling device can only be used once.

 However, the main object of the present invention is a significant simplification of the sampling system defined in the preceding lines.

 The invention provides for this purpose that the aforementioned support is provided with a metal screen provided with an inner cardboard screen acting as a delay screen.

 It has been unexpectedly found that this internal delay screen has a particularly favorable effect on the quality of the sample. Indeed, the results of comparative tests carried out with and without a delay screen show that, in the first case, the samples are much less porous and lend themselves better to metallographic examination than in the second case.

So far, a fully satisfactory scientific explanation for this phenomenon has not yet been found.

It is assumed that the destruction of the delay screen in the molten metal bath has a calming effect on the molten metal, especially in the case of cast iron or molten steel.

The characteristics of the invention will emerge more clearly from the following detailed description of two embodiments, given without any restrictive intention and illustrated by the appended drawing, where
FIG. 1 represents a sampling device according to the invention, partially in axial section; and
Figure 2 shows on a larger scale another embodiment of the essential part, characteristic of the device according to the invention.

As can be seen with reference to FIG. 1, the device shown therein consists of a container 1, slid into a support 2 made of a refractory material, such as foundry sand. The access channel to the container 1 is in the form of a small quartz tube 3, with or without a cooling device 4.

 Said support 2 is introduced into the end of a cardboard tube 5.

 According to the system of the invention, the access channel 3 is protected by a metal screen 6, made for example of steel with a thickness of barely 0.2 mm. In addition, according to the invention is also provided between the screen 6 and the support 2 a cardboard disc 7 acting as a delay screen.

 In the example of implementation according to FIG. 1, said screen 6 is executed in the form of a bowl, although, according to FIG. 2, it can also be in the form of a disc. The small thickness of the screen 6 excludes any risk of adhesion of slag by solidification.

 Compared to known sampling devices, the construction described in the preceding lines is not only considerably less expensive, but also gives, as already said, significantly better results with regard to the porosity of the samples thus taken.

Claims (5)

CLAIMS. 1.- An improved device for taking samples of molten metals, of the type comprising a support provided with an access channel opening to the outside, characterized in that this channel (3) is protected by a metal screen (6) fixed on the support (2), a delay screen (7), made of cardboard, being provided between the support (2) and the metal screen (6). 2.- improved sampling device according to claim 1, characterized in that said metal screen (6) is executed in the form of a bowl.  3.- improved sampling device according to claim 1, characterized in that said metal screen (6) is executed in the form of a disc.  4.- improved sampling device according to claim 1, characterized in that said metal screen (6) is made of steel and has a thickness of about 0.2 mm. 5.- improved sampling device according to claim 1, characterized in that said delay screen (7) is in the form of a cardboard disc.