JPH03151157A - Method for coating inner face in metallic cylinder - Google Patents

Abstract

PURPOSE:To manufacture a metallic cylinder welded perfectly between different kind metals by inserting powdery different kind metallic raw material into the inner face of the metallic cylinder, heating and melting it with a heater, rotating the metallic cylinder and forming coating layer having the different kind metal. CONSTITUTION:The metallic cylinder 9 for forming the coating layer in the inner face is fitted to an exclusive jig 10 and flange 12 thereof is fixed to a pipe 1 in a rotating device, and a graphite heater 17 for heating the inner face and a water cooling pipe 21 are set to the prescribed position in the metallic cylinder 9. Successively, the rotating device body is rotated with a motor 5, and by inserting a trough-like pipe into the inert pipe 24 from the end face of the water cooling pipe 21, a slag forming material is charged into the metal cylinder 9 and a metal raw material feeding nozzle 27 is inserted from the end face of water cooling pipe to fix it to an automatic carriage 26. Further, by heating it with the heater 17, slag forming material is sufficiently melted, and when the temp. reaches the prescribed temp., the metallic raw material for coating the inner face is injected from a nozzle 27 to execute the coating. By this method, the coating layer stuck uniformly and firmly to the inner face of the metallic cylinder 9 under air atmosphere is formed with centrifugal force.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming a dissimilar metal coating layer on the inner surface of a metal cylinder.

(Prior art) As a method for forming a dissimilar metal coating layer on the inner surface of a metal cylinder,
Methods for manufacturing hollow quartz ingots include overlay welding methods such as MIG welding and powder plasma welding, double centrifugal casting methods, HIP methods, and methods for manufacturing cylindrical ingots by heating from the inner surface of the cylinder. method is known.

(Problem to be solved by the invention) However, in the overlay welding method, in order to prevent welding defects such as cracks, there are limits to both the overlay material and the base material, and the range of components that can be selected is considerably restricted. be. In addition, in overlay welding, since welding is performed by overlapping beats, hardness and structure unevenness at the node boundary cannot be avoided.

As a result, bead patterns occur during use, which is one of the causes of trouble during use. Also, recently, with the aim of improving wear resistance, it has been carried out to build up a weld structure in which non-metallic particles such as carbides, oxides, and borides are dispersed in the weld metal. If the ratio of nonmetallic particles to the base metal is increased, cracks are likely to occur, so it is necessary to keep the ratio low to a certain extent to prevent cracks from occurring.

Regarding the centrifugal casting method, research has also been conducted on the production of double pipes using the double centrifugal casting method, but there are limitations such as the timing of injection and the temperature of the molten metal when injecting the outer surface metal and then the inner surface metal. The problem is that it has a large effect on the welding and penetration conditions of the parts, and is extremely difficult to control.
It is difficult to obtain complete welding of the interface.

Although it is possible to freely select the tissue in HIP, l
The cost is high because it is done in batches, and it is not done by boat.

The method of producing ingots by heating from the inner surface of the pipe is intended for producing quartz pipes in the atmosphere, but when this method is used to form a coating layer on the inner surface of a metal cylinder, the Since the powdered metal raw material used in this process oxidizes in the atmosphere, a good coating layer cannot be formed. Furthermore, in order to create a vacuum or an inert atmosphere inside the metal cylinder, the equipment becomes complicated and expensive.

Therefore, the present invention aims to easily form a coating layer on the inner surface of a metal cylinder in the atmosphere by heating from the inner surface, without generating a bead pattern, and to improve the structure of the coating layer and the non-metal particles in the coating layer. The purpose of this invention is to freely change the proportion of the base metal and to obtain a coating layer on the inner surface of the metal cylinder that is evenly and firmly adhered to the base metal.

(Means for solving problems) The gist of the present invention is as follows.

(1) Powdered dissimilar metal raw materials inserted into the inner surface of the metal cylinder are heated and melted by a heater inserted into the metal cylinder inner surface, and dissimilar metals are applied to the inner surface of the metal cylinder by the centrifugal force generated by rotating the metal cylinder. Cover layer.

A metal cylindrical inner surface coating method characterized by forming.

(2) When heating and melting powdered dissimilar metal raw materials in the atmosphere, a slag forming material is inserted into the inner surface of a metal cylinder in advance, and the slag forming material is melted by heating with a heater to form a molten slag, and then the powder is Inserting a different metal raw material in the form of a metal cylinder into the inner surface of the metal cylinder and melting the metal raw material through a molten slag layer, or inserting a powdered different metal raw material in advance, and then inserting a slag forming material, The method for coating the inner surface of a metal cylinder according to item 1 above, characterized in that the slag forming material is melted by heating with a heater, and the powdered dissimilar metal raw material is melted through the melted slag.

(3) After the slag forming material inserted into the inner surface of the metal cylinder is heated and melted by a heater, the molten metal previously melted in a melting furnace is injected into the inner surface of the metal cylinder, further heated by a heater, and the metal cylinder is heated. A method for coating the inner surface of a metal cylinder, characterized in that a coating layer of a dissimilar metal is formed on the inner surface of the metal cylinder by centrifugal force caused by rotating the metal cylinder.

(4) When using an AC power source as the heating power source for the heater,
4. The method for coating the inner surface of a metal cylinder according to any one of items 1 to 3 above, which uses a heater having slits in the length direction of the heater in order to prevent generation of induced current.

In the present invention, when forming a coating layer of a dissimilar metal on the inner surface of a metal cylinder in the atmosphere, the slag forming material that has been inserted into the inner surface of the metal cylinder in advance and held on the inner surface of the cylinder by centrifugal force is melted by heater heating from the inner surface. However, by covering the inner surface of the metal cylinder, it is possible to prevent the oxidation of the metal raw material that will be used as the coating layer that will be added later or that has been added in advance, and to form a good coating layer.

In the conventional centrifugal casting method, the temperature of the molten metal decreases over time because the molten metal is not heated by any other heat source after pouring. Therefore, even in double centrifugal casting, a very high level of technology is required to completely weld the outer layer, inner layer, and boundary. Furthermore, with the centrifugal casting method, it is difficult to weld dissimilar metals to the inner surface of a pipe prepared in advance, and with the centrifugal casting method, it is extremely difficult to obtain a composite vibe in which dissimilar metals are perfectly welded.

On the other hand, in the present invention, since the molten coating material can be continuously heated by a heater for a certain period of time even after pouring, the coating metal can be completely welded to the base material.

Furthermore, if metal is melted in the atmosphere, the molten metal will be oxidized, and the coating metal will contain many oxides, pores, etc., making it impossible to obtain a healthy coating layer.

In order to solve this problem, the present invention provides a method in which a molten slag is formed and inserted in advance, or a coated metal raw material inserted after slag formation is melted through the molten slag. Invented.

According to the method of the present invention, the coating metal raw material is isolated from the atmosphere by the molten slag and melted, so it is not oxidized by the atmosphere and a healthy coating layer free of oxides, pores, etc. can be obtained. .

In addition, in the method of the present invention, it is also possible to use a method in which molten metal previously melted in a melting furnace is injected into the inner surface of the metal cylinder, similar to the centrifugal casting method. The material is melted by heating with a heater, and then
By injecting molten metal and further heating it with a heater, it is possible to weld different metals to the inner surface of the metal cylinder.

Next, an apparatus for coating the inner surface of a metal cylinder according to the present invention will be explained with reference to the drawings. The device is a rotating device.

It can be broadly divided into three types of equipment: a heating device and a coating metal raw material supply device. Further, when injecting molten metal, it is necessary to provide a melting furnace and a gutter for injecting molten metal.

FIG. 1 is an explanatory diagram of a metal cylinder rotating device for carrying out the present invention. In the figure, a pipe 1 is supported by two bearings 2, and the bearing cases of the bearings are fixed to a base. A pulley 4 is attached to the outer surface of the pipe 1, and is connected by a belt to a pulley 6 attached to the drive shaft of a motor 5 fixed on the same base as the bearing case. The energy of the rotation of the pulley 6 is thereby transferred so that the pipe 1 rotates about its horizontal axis. pipe 1
A small-diameter pipe 7 is inserted into the inner surface of the pipe 1 so as to have the same horizontal axis as the pipe 1, and the flange on one side of the pipe 7 is fixed to the pipe 1 with bolts. This is due to internal heating,
This is because when the pipe 7 expands, the expansion is released at the opposite end face. Insulating material 8 is placed in the gap between pipe 1 and pipe 7.
is inserted to prevent heat from internal heating from being transmitted to the bearing 2, thereby preventing the bearing from being damaged by heat.

The metal cylinder 9 to be coated on the inner surface is housed with a solid refractory material 11 inside a special jig 1O designed to be installed inside the main body of the rotating device so as to have the same horizontal axis as the special jig, and the flange 12 and fixing vibrators 13 and 14 to be fixed to the dedicated jig 10. At both ends of the metal cylinder 9, so as to prevent the slag forming material and coating metal powder from coming out to the outside.
A flange 15 having an inner diameter smaller than that of the metal cylinder 9 is fixed by welding. The gap between the metal cylinder 9 and the dedicated jig 10 is filled with particulate heat insulating material 6.

A special jig lO with a metal cylinder 9 fixed inside is a pipe 1
It is fixed to the end face with bolts so that it has the same horizontal axis as the pipe 1.

The pipe 1 may be rotated by turning as in the conventional centrifugal casting method. Moreover, the metal cylinder 9 is
As shown in FIG. 2, it may be attached to the end surface of the pipe 1, and any method may be used as long as it meets the purpose of the present invention.

The inner surface heating heater 17 has a cylindrical shape as shown in FIG. 3, and two slits extend along the entire length from one end face to the other end face, leaving a distance of 50 mm.

Also, the material used is graphite. However, any heater may be used as long as it is a high temperature heating element such as silicon carbide.

The procedure for installing the heater 15 is shown in FIG. The heater holder 18 is made of copper and is divided into upper and lower halves, and its inner surface is water-cooled.

Align the slit 17' of the heater 17 with the heater holder division position, and insert the insulating ceramic plate 1 into the slit 17'.
9 and tighten the bolt 20 to fix the heater 17. In this case, the bolt 20 must be prevented from coming into contact with the heater holder 18 by using an insulating pipe or an insulating washer. The upper and lower portions of the heater holder 18 are respectively connected to output cables from the heater transformer.

In this device, the heater 17 forms a U-shaped circuit, but it is also possible to heat the heater 17 by holding both ends with heater holders 18 without making a slit. still,
It is cheaper in terms of equipment to use alternating current as the power source for the heater. However, in this case, if alternating current is used as the power source,
An induced current is generated in the metal cylinder 9, the special jig lO1, or the pipe 1.7 of the rotating device main body, causing electrolytic corrosion in the bearing. As a countermeasure against this problem, the present invention uses a U-shaped heater in which a slit 17' is provided in the longitudinal direction of the heater 17, as shown in FIG. By doing so, no induced current is generated and electrolytic corrosion of the bearing can be prevented. Other measures include using direct current as a power source, changing the rotating device from a bearing type to a turning type, and using rubber rollers.

A water cooling pipe 21 having an outer diameter smaller than the inner diameter of the heater is inserted into the inner surface of the heater 17 to protect the coating metal raw material supply device. This water cooling pipe has a double structure as shown in FIG. 5, and is constructed so that cooling water circulates between the water cooling pipe 21 and the inner pipe 24.

A heat insulating material 23 is attached to the outer surface of the water-cooled vibe 21. This heat insulating material also serves as an insulating material when it comes into contact with the heater 17.

A pipe having an outer diameter smaller than the inner diameter of the inner pipe can be inserted into the inner pipe 24 from the end surface thereof, and a slit is opened on the outer surface of the inner pipe 24 through the water-cooled vibe 21. Therefore, using this inner pipe 24, it is possible to send powdered metal raw material or slag forming material into the coating metal cylinder 9. However, in this case, it is necessary to open a slit in the heater at the position where the powder falls.

A mixing device 25 for mixing powdered metal raw material and carrier gas is mounted on a self-propelled trolley 26 and further connected to a metal raw material feeding nozzle 27 inserted into the inner pipe 24 . The self-propelled trolley 26 can repeatedly move back and forth within a certain range using limit switches attached to the front and rear surfaces, and uniformly distributes the coating metal raw material or slag to a designated location within the coating metal cylinder 9. It is possible to spray the forming material. Furthermore, it is also possible to insert a gutter-like pipe into the vibrator 24 and similarly introduce the metal raw material for coating and the slag forming material.

Figure 6 shows a device for injecting molten metal. A gutter 28 mounted on a trolley is inserted from the opposite side of the heating heater 17, and the molten metal transferred from the melting furnace to the ladle is passed through the gutter. and inject it into the inner surface of the metal cylinder 9 for coating. At this time, the heater 17 is pulled out of the rotating device. After the molten metal is injected, the gutter is quickly pulled out, the heater 17 is inserted, and the heater is heated.

Next, a powdered metal raw material is used in the process of forming a dissimilar metal coating layer on the inner surface of a metal cylinder using this apparatus. An example of the case is shown below.

(1) Attach the metal cylinder for forming the inner coating layer to a special jig,
Fix it to the rotating device body.

(2) Install the graphite heater for internal heating and the water cooling pipe in the specified position.

(3) Rotate the rotating device main body.

(4) Insert the gutter-shaped pipe into the inner pipe from the end of the water-cooled pipe, and introduce the slag forming material into the metal cylinder.

(5) Insert the metal raw material feeding nozzle from the end of the water-cooled pipe and fix it to the self-propelled trolley. Move the self-propelled trolley back and forth to set the powder injection position.

(6) Heat the heater to melt the slag forming material.

(7) After the slag forming material is sufficiently melted and its temperature reaches a predetermined temperature, the metal raw material for inner surface coating is introduced.

(8) After inserting the metal raw material, stop heating the heater and finish coating.

The powdered metal raw material for coating may be charged into the metal cylinder before the slag forming material in step (4).

It is also possible to introduce the slag forming material into the metal cylinder using a carrier gas.

The slag forming material used preferably has good fluidity and has a melting point equal to or lower than the powder metal raw material for coating. This is to prevent the slag temperature from increasing more than necessary when the powdered metal raw material for coating is introduced after the slag forming material is melted.

When the powder metal raw material is coated on the inner surface of a metal cylinder according to the present invention, melt penetration may occur between the coating layer and the base material. If the weld penetration is deep, it is difficult to obtain the original characteristics of the coating layer metal. The depth of this melt penetration depends on the melting points of the base metal and coating metal, the amount of heat from the heater, and the amount of powdered metal raw material to be sprayed.

Since it has a close relationship with coating time, molten slag temperature, etc., by controlling these appropriately,
Good cross-sectional properties with almost no melt penetration can be obtained. Usually, it is desirable to use a powdered metal raw material with a melting point lower than that of the base material, and to maintain the molten slag temperature below the melting point of the base material and above the melting point of the powdered metal raw material, and perform coating.

Furthermore, in the present invention, since the molten slag temperature can be maintained freely, it is also possible to disperse various dispersants such as carbides, oxides, and borides into the coating layer without melting them. However, in this case, G (gravitational acceleration (+/sec"))
is effective, so the specific gravity of the coating metal and the dispersion material becomes an issue.

Furthermore, it is possible to obtain coating layer properties that are difficult to obtain with conventional welding and casting methods, in which only the dispersed material is densely aggregated due to the difference in specific gravity, and the coating metal fills the gaps.

It is also possible to further coat the inner surface of the composite pipe manufactured according to the present invention, and a composite pipe with three or more layers can be manufactured. It is also possible to stack layers by continuous operation.
After finishing the coating work on the inner surface, the inner surface temperature is lowered and the coated metal is completely solidified, and then the heater is heated again and the next coating is applied, so that lamination can be freely performed.

Moreover, as shown in FIG. 7, by removing the pipe that becomes the outer cylinder of the composite pipe manufactured in the present invention,
The layer coated on its inner surface can be used as the outer surface of the pipe in single or composite pipes.

Regarding the rotation speed in the present invention, in principle, it is sufficient that the slag forming material and powdered metal raw material in the metal cylinder, or their molten products, can be retained on the inner surface of the metal cylinder, but usually centrifugal casting is used. G (gravitational acceleration (m/s
ec) range (40-130G) is desirable.

Examples of the present invention will be described below.

(Example 1) According to the present invention, an inner coating layer was formed on a pipe of the following size. The sample material dimensions are φ200 x φ230 x 340!
! The material used was STKM-13A.

Stellite Nα1 was used as the coating metal, and the slag forming material was blended and melted to have the components shown in Table 1, and the resulting lumps were pulverized and used.

Table-1 Slag forming material composition Rotation speed 73Orpm, heater output 90-130Kw
The coating was performed at a metal powder injection temperature of 1350°C.

Add 5 kg of metal powder and create a wall thickness of 2 to 311 II on the inner surface.
A coating layer of lt was formed.

After coating, a sample was taken from the sample material,
The properties of the cross section were investigated. Almost no penetration was observed, and a uniform coating layer was obtained.

(Example 2) Next, an application example of the method of the present invention will be shown.

The test material used was the same as in Example 1 in terms of material and dimensions.

The inner coating material is 6k WC grains (28-60 mesh)
g, 3 kg of Colmonoy was used. Further, the slag forming material used was a mixture of 300 g of creolite (NaaAJ F h) per 1 kg of the material shown in Example-1.

The coating process includes 1. Add WC grains, 2. Add slag forming material, 3. Melt the slag forming material by heating from the inner surface, 4. Introducing Kolmonoy, 5. The operation was performed by cooling.

The rotation speed is 730rp+* (60G), the heater output is 0 to 120Kw, and the metal powder input temperature is 1300°.
Coating was performed with C.

After coating was completed, a sample was taken from the sample material and a cross-sectional investigation was conducted. The cross section has a structure in which WC grains are densely dispersed and colmonoids have penetrated into the gaps. In addition, there were no defects such as cranks, and good coating properties were obtained. A photograph of the cross-sectional structure is shown in FIG.

(Effect of the invention) The present invention provides the following effects.

(1) Unlike the conventional centrifugal casting method, since the coating material can be heated continuously from the inner surface even after melting, it is possible to obtain a metal cylinder with complete welding between dissimilar metals.

(2) By using a slag forming material, a coating layer of a different metal material free of oxides and pores is formed on the inner surface of a metal cylinder in the atmosphere.

(3) W that was impossible with conventional powder plasma welding, etc.
It is possible to obtain an inner surface coating layer having an extremely large amount of particles such as C dispersed therein.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view of an apparatus for implementing the present invention, Fig. 2 is an explanatory diagram showing a modification of the method for attaching a metal cylinder for coating, Fig. 3 is a perspective view of a graphite heater, and Fig. 4 is a diagram of a heater. Figure 5 is a cross-sectional view of a water-cooled pipe, Figure 6 is a vertical cross-sectional view of a device used to inject pre-melted molten metal, and Figure 7 is a diagram of a composite pipe manufactured according to the present invention. FIG. 8 is an optical microscope photograph showing the metallographic structure of the cross section of the sample material obtained in Example 2. Figure 3/7 Figure 4 8 Fifth! m

Claims (4)

[Claims] (1) Powdered dissimilar metal raw materials inserted into the inner surface of the metal cylinder are heated and melted by a heater inserted into the metal cylinder inner surface, and dissimilar metals are applied to the inner surface of the metal cylinder by the centrifugal force generated by rotating the metal cylinder. A method for coating the inner surface of a metal cylinder, characterized by forming a coating layer. (2) When heating and melting powdered dissimilar metal raw materials in the atmosphere, a slag forming material is inserted into the inner surface of a metal cylinder in advance, and the slag forming material is melted by heating with a heater to form a molten slag, and then the powder is Inserting a different metal raw material in the form of a metal cylinder into the inner surface of the metal cylinder and melting the metal raw material through a molten slag layer, or inserting a powdered different metal raw material in advance, and then inserting a slag forming material, 2. The method for coating the inner surface of a metal cylinder according to claim 1, wherein the slag forming material is melted by heating with a heater, and the powdered dissimilar metal raw material is melted through the melted slag. (3) After the slag forming material inserted into the inner surface of the metal cylinder is heated and melted by a heater, the molten metal previously melted in a melting furnace is injected into the inner surface of the metal cylinder, further heated by a heater, and the metal cylinder is heated. A method for coating the inner surface of a metal cylinder, characterized in that a coating layer of a different metal is formed on the inner surface of the metal cylinder by centrifugal force caused by rotating the metal cylinder. (4) When using an AC power source as the heating power source for the heater,
The method for coating the inner surface of a metal cylinder according to any one of claims 1 to 3, wherein a heater having a slit in the length direction of the heater is used to prevent generation of induced current.