KR19980041066U - Multi-nozzle gas spraying device for composite roll manufacturing - Google Patents

Abstract

The present invention relates to a multi-nozzle gas spraying device for producing a composite roll, which is capable of producing a composite roll having no segregation and excellent physical properties by nurturing spray casting on an annular mandrel, and including a tundish (4) for accommodating molten metal, and On the sprayer 20, which is mounted to the lower molten orifice 5 of the tundish 4 and sprays high pressure gas to the molten metal discharged from the orifice 5, and spray droplets of the molten metal. In the apparatus for producing a composite roll by the spray casting method, the apparatus has a substrate (2) on which the core rod (1) can be mounted to be able to move up and down and rotate, and a plurality of atomizers are arranged on concentric circles about the rotation center of the substrate (2). 20 is installed, and the positions of the spray droplets sprayed from each of these sprayers 20 are characterized by having different concentric circles.

Description

Multi-nozzle gas spraying device for composite roll manufacturing

The present invention relates to a spray casting apparatus, and more particularly, to a multi-nozzle gas spraying apparatus for producing a composite roll, which is capable of producing a composite roll having no segregation and excellent physical properties by growing spray casting on an annular mandrel.

Commonly known composite roll manufacturing methods include centrifugal casting, forging, and continuous pouring process for cladding (CPC). Centrifugal casting method is to inject molten outer layer material into centrifugal casting machine to make outer layer of appropriate thickness first, and then to immediately inject inner layer material to cast rolls with different outer and inner components, and forging method is to make one ingot with outer layer material. It is a method of manufacturing by forging it, and the CPC method is to inject the outer layer material molten metal between the vertical core material and the water-cooled mold while fusion and solidification of the core material while gradually moving the core material to the lower side. Cladding method (ISIJ Inter., 32 (1992) 11, pp1202-1210).

However, the forging method is not only high manufacturing cost but also fine grain size and segregation is severely limited to the thickness of the outer layer material. The centrifugal casting method is somewhat inexpensive but difficult to control the cooling rate, which makes it difficult to control the structure, coarse grains and somewhat segregation occurs. The CPC method not only makes it difficult to increase the thickness of the outer layer material by 100 mm or more or several mm, but also makes the manufacturing impossible when the inner layer material has a very large diameter. In addition, when manufacturing a composite roll having a large difference in diameter of the inner layer material, there is a disadvantage of introducing a new facility.

The present invention has been made to solve such a conventional problem, the object of the present invention is to provide a multi-nozzle gas spraying device for producing a composite roll to be able to produce a composite roll of various diameters with excellent properties.

1 is a front view showing a multi-nozzle gas spraying device for producing a composite roll according to the present invention

Figure 2 is an explanatory view showing the principle of determining the angle of the gas injection unit and the radius of the nozzle hole of the multi-nozzle gas spraying device for producing a composite roll according to the present invention

Figure 3 is a schematic configuration diagram showing a state in which four gas injectors are mounted on the multi-nozzle gas spraying device for producing a composite roll according to the present invention.

* Description of the symbols for the main parts of the drawings *

1 ... mandrel

2 .... Substrate

3 .... Induction heating device

4 ... Tundish

5. Molten Orifice

6. Gas nozzle

7. Outer layer material

20 .... Atomizer

As a technical configuration for achieving the above object, the present invention, a tundish for accommodating the molten metal, and is mounted on the lower molten orifice of the tundish and spraying the molten gas discharged from the orifice to the molten metal In the apparatus for producing a composite roll by the spray casting method by a spray gun consisting of a gas nozzle to spray droplets, having a substrate that can be moved up and down and rotated by mounting a core rod, a plurality of concentric circles on the rotation center of the substrate A sprayer is installed, and the position of spray droplets sprayed from each of these sprayers is to provide a multi-nozzle gas spraying device for producing a composite roll, characterized by having different concentric circles.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a cross-sectional configuration diagram showing a multi-nozzle gas spray device for producing a composite roll according to the present invention, there is an induction heating device (3) for preheating the mandrel, this induction heating device (3) is capable of rotating and vertical movement It is placed on top of the substrate 2.

In addition, a plurality of atomizers 10 are installed at positions of the concentric circles with respect to the center of the mandrel 1. The nebulizer 20 has a tundish 4, a molten orifice 5 is formed at a lower side of the tundish 4 to discharge molten metal to a lower side, and an orifice (outside the orifice 5). A gas nozzle 6 for atomizing the molten metal discharged from 5) by blowing with high pressure air is provided. The centers of the melt sprayed from each of these sprayers are positioned differently so that the layers grown for each sprayer are different. That is, one sprayer is positioned to raise the surface of the mandrel 1, the other sprayer is positioned to raise the upper side than the surface layer portion of the mandrel 1, and the other sprayer to raise the outermost raised. The nebulizer is grown by dividing from the innermost to the outermost of the thickness to be spray-grown according to the number. In addition, the position where the nebulizer is placed should be appropriately set according to the number of nebulizers. In the case of four sprayers, center the core rods (1) at 90 ° intervals and in the case of three, they are located at 120 ° intervals.

Figure 2 is an explanatory view for explaining the action by the multi-nozzle gas spraying device for producing a composite roll according to the present invention, by raising the position of the substrate to the dotted line 30 to operate the induction heating device for preheating at the same time rotation Warm up the mandrel.

When the mandrel reaches the preheating temperature, the substrate is slowly lowered. When the substrate reaches the lower proper position, each atomizer 20 is operated to spray the molten metal therefrom. The molten molten metal is laminated on the substrate by the molten metal sprayed while continuously lowering, and thus the core rod is grown.

When producing a large composite roll with a single sprayer, it is very difficult to spray the entire thick layer with one sprayer. And, when the diameter of the composite roll is large, the time until the layer sprayed on one surface of the growth layer is sprayed and sprayed at the position again is very long, and the surface is already completely solidified. When spraying is performed on the solidified layer, it is impossible to obtain a growth layer of good quality. If the rotational speed is increased to reduce one rotation time, the centrifugal force is increased, and the surface of the spray-growing layer having a high temperature drops radially. Therefore, the use of a large number of atomizers as in the present invention can solve this problem.

With the use of multiple sprayers, spray growth can be repeated by the next sprayer before the surface of the build layer is completely solidified, allowing spray growth in the reaction solid state. In addition, the position of the thickness in charge of a plurality of atomizers is different, it is possible to produce a large complex or to grow thick. In addition, it is possible to manufacture a multi-layer composite roll by different melt composition for each sprayer.

On the other hand, in the spray casting process, the amount of sprayed molten metal deposited on the substrate per hour has a decisive influence on the shape, size and final microstructure of the molded body, so that the deposition rate control of the spray capacity according to the substrate radius is essential.

The molten metal flows out downward through the molten orifice, and the gas injector is atomized by the high-speed gas injected through the nozzle hole. Each gas injector stacks spray droplets toward different radii of the substrate, and the shape of the composite roll is determined by the lamination position on the substrate and the inner diameter of each molten orifice. Changes should be made in relation to the size of the injector nozzle hole. In order to make the outer layer growth height uniform, the amount of molten metal to be laminated increases as the number of molten metals decreases and the radius increases toward the center of the substrate.

In the case of a circular substrate, the inner diameter of the molten orifice should be increased so that the amount of spray droplets increases toward the outer radius of the substrate in order to make the stacking height uniform. In addition, in order to uniformize the size of the spray droplets to be laminated, the amount of injection gas must be increased in proportion to the amount of molten metal flowing out, so that the gas outflow cross-sectional area of the corresponding gas injector must be changed according to the amount of molten molten metal.

Gas outlet cross-sectional area of the gas size enemy spraying liquid in spraying process is determined by the ratio of the outlet melt amount and the injection amount of gas, the spray droplet diameter (d) is outlet cross-sectional area (A _melt), a gas injector of the melt orifices (A _gas) And as a function of the gas injection pressure (p _o ) can be expressed as in the following equation 1.

Since the injection gas pressure is constant during the spray casting process, a uniform droplet size can be expected by maintaining a constant ratio between the melt flow area and the gas flow area. Figure 2 illustrates a method of determining the inclination angle of each gas injector and the inner diameter of the molten orifice in the present invention in order to open a uniform droplet size and the same outer layer growth height. In case of applying n gas injectors (divided into eight for convenience), the gas injectors are arranged in the rotational direction every 360 / n ° at the same height (H) and the same radius (D). They have different angles of inclination (psi) and are directed at different positions on the substrate. In this case, the rotating substrate may be divided into n area elements in the radiation direction to determine the amount of melt flowing out of each area element and the gas outlet cross-sectional area of the gas injector for obtaining a uniform droplet size. Through mathematical calculations, the area division governing equation of the substrate for determining the internal diameter of the molten orifice of the kth area element can be expressed as follows.

A _k = (ad + β) · A ₁ ..... Equation 2

α + β = 1 .... Equation 4

δ + ε = 1 ... Equation 5

In Equation 2 to 5, there are methods for dividing the rotating substrate into various aspects by changing the values of α and β, but they can be divided into two extreme categories.

The first is an equal interval division, which has a relationship of x _k -x _k-1 = x _{k + 1} -x _k , and the second is an equal area division, which has A _k = A _{k + 1} relationship. . These extreme conditions and typical partitioning conditions existing between them are summarized in Table 1 below.

When the division method falls between the two extreme conditions described above, that is, 0 α 2, the arrangement of the gas injector can be expected to be easy and effective spray deposition conditions. If the two extreme conditions deviate, i.e., α 0, the division interval is too narrow in the outer part, and spray droplets spilled from adjacent gas injectors are superimposed and ineffective, and in case of α 2, the division interval in the outer part This is so wide that the inner diameter of the molten orifice must be excessively large, making it unrealistic. In case of iso-area splitting, the inner diameter of the molten orifice applied to each gas injector and the gas outflow cross-sectional area are the same, which is the easiest condition for practical application.

The inner diameter (r _k ) of the molten orifice of the k-th gas injector for obtaining a uniform spray droplet, the mean point (x ' _k ) _{where the} spray droplet collides with the substrate, and the gradient of the gas injector (ψ _k ) are described above. Can be determined as follows.

Of course, the number of gas injectors can be arbitrarily determined, but by adjusting the total number so that the spraying intervals from the gas injectors do not overlap with each other by using the above equations, a uniform spray droplet size and rod-shaped article manufacturing can be achieved. A suitable spray density by radial position can be expected. In the manufacture of small-diameter composite rolls, two or three gas sprayers can be applied.In particular, in the manufacture of large-diameter composite rolls, four or six gas injectors can be arranged to maintain high productivity. do. 3 schematically shows a combined roll manufacturing apparatus in the case of four gas injectors are installed.

The composite roll is manufactured by the spray manufacturing process by atomizing a metal molten metal with a high pressure gas, and then laminating fine spray droplets on a lower rotating substrate in a reaction state. As a state-of-the-art alloy manufacturing method that can produce an alloy molded body, the general effect of the alloy production method by the spray casting method is that it can obtain a microstructure small crystal grains, can obtain a microstructure without segregation, compared to the general casting method The solidification rate is high, so that the solid solution limit can be increased above the equilibrium concentration, and the physical properties can be improved by uniformly and finely dispersing precipitates such as carbides.

In addition, by using a plurality of atomizers on a concentric circle as in the present invention, the solid state droplets sprayed by another atomizer are covered before the solidified atomized droplets are solidified by one atomizer. It should be possible to manufacture composite rolls without segregation and excellent physical properties.

As described above, according to the multi-nozzle gas spraying device for producing a composite roll according to the present invention, the spray casting is nurtured on the annular mandrel by installing a plurality of injectors configured to spray the reaction droplet spray droplets on the annular mandrel. There is no segregation and has an excellent effect of producing a composite roll having excellent physical properties.

Claims (1)

It is attached to the tundish 4 for accommodating the molten metal and the molten orifice 5 on the lower side of the tundish 4, and sprays a high pressure gas to the molten metal discharged from the orifice 5 to spray the molten liquid. In the apparatus for producing a composite roll by the spray casting method by the atomizer 20 made of a gas nozzle (6), It has a substrate (2) on which the mandrel (1) can be mounted to move up and down and rotate, and a plurality of sprayers (20) are installed on concentric circles with respect to the center of rotation of the substrate (2). Multi-nozzle gas spraying device for producing a composite roll, characterized in that the position of the spray droplets sprayed from each having a different concentric circles.