KR20000063250A - Repair method of crank case corroded of disel engine for marine craft - Google Patents

Abstract

PURPOSE: A method for regenerating corroded part of a marine diesel engine crankcase is provided to extend the life span of the crank case by continuously regenerating the sectional corrosion of the crank case. CONSTITUTION: A method for regenerating corroded part of a marine diesel engine crankcase(10) includes the steps of removing the corrode part by mechanical machining, preliminarily processing the corroded part to increase adhesion surface area in the corroded part by mechanical machining, coating a bond layer(20) on the preliminarily processed corroded part for improving the adhesion force between a succession metal coating layer and the parent metal and compensating the difference of coefficient of thermal expansion between the succession metal coating layer and the parent metal, and coating a top coating layer(23) having excellent machining and corrosion resistance on the upper part of the coated bond layer.

Description

Repair method of crank case corroded of disel engine for marine craft}

The present invention relates to a repair technique for repairing corrosion parts of mechanical parts, and more particularly, to a regeneration method of regenerating corrosion parts of a diesel engine by corrosion spraying of a marine diesel engine.

Marine diesel engines are mainly used as a power source for sailing or fishing vessels, so they must be designed and manufactured to withstand the conditions of long-term operation at sea. Due to these conditions of use, the characteristics required for marine diesel engines and various parts used therein are durability and corrosion resistance.

Crankcase, one of the core components of marine diesel engines, forms the combustion chamber, the lubricating oil passage and the coolant passage of the engine, and supports the crankshaft that generates rotational force by the explosion force of the engine combustion chamber.

The crankcase of the marine diesel engine is a cylinder liner 13 is partially mounted inside the crankcase 10 made of cast iron or a non-ferrous alloy such as cast steel or aluminum, as shown in Figure 1, the outer diameter of the cylinder liner 13 And a space is formed between the inner circumferential surface of the crank case 10 in contact with it and serves as a coolant passage 15.

In general, marine diesel engines are high-power engines, so high heat is generated during engine operation. For this reason, the crank case in which the cylinder liner 13 of the upper liner tuck assembly 17 of the upper liner jaw assembly 17 is assembled, is circulated with the cooling water in the cooling water passage 15 formed in the crank case 10. Long term penetration into the bore of (10) causes localized corrosion.

As such, when local corrosion occurs on the upper cylinder liner jaw assembly 17 of the upper crankcase 10 by the coolant, the engine may be leaked into the diesel combustion chamber in case of serious problems, such as vibration of the cylinder liner 13. Sometimes it stops. And even in the early minor local corrosion, this corrosion can reduce the engine's efficiency and become the root cause of accidents.

In a related industrial site, when a defect caused by such local corrosion occurs in a crankcase of a marine diesel engine, the crankcase itself, which is a core part of the engine, is usually replaced.

However, the crankcase of a marine diesel engine is an expensive part that is not only very difficult to manufacture technology but also expensive to manufacture because it is a complicated structure and a core component that should be used for the longest of engine components. Therefore, it is required to reuse the crankcase by regenerating the defective part rather than replacing the whole part because the local defect has occurred.

As a method of repairing local corrosion defects known to date, a bush repair method is known. However, these repair methods are expensive due to the high number of work processes, and once repaired, they cannot be repaired again, and when the engine is operated using the repaired parts, durability is reduced and bushes are removed during repair. Coolant leaks and lacks reliability from ship operations.

Therefore, there is a need for a reliable method for repairing a crankcase localized corrosion defect site that is simple in operation and can impart the same or more properties as the original product.

The present invention is to solve the above problems, an object of the present invention is to remove the defective parts by machining in a simple working process, if local corrosion defects in the marine diesel engine, corrosion resistance to the parts where the defective parts are removed The present invention provides a method for regenerating corrosion parts of a marine diesel engine that sprays metal to reclaim defective parts.

1 is a cross-sectional view of a crankcase for a general marine engine.

Figure 2 is a schematic cross-sectional view of the metal-spray coated repair part.

In order to achieve the object of the present invention, the present invention provides a method for regenerating and repairing corrosion defects generated by cooling water of a marine diesel engine crankcase, the defect removal process of removing the corrosion defects by mechanical processing; A pretreatment step for increasing the adhesion surface area by mechanical processing on the corrosion defect portion from which the defect is removed; A bond layer coating process for improving the adhesion between the subsequent metal coating layer and the base metal to the pretreated bonding portion and buffering the difference in coefficient of thermal expansion between the two metal layers; Top coating layer coating process excellent in machinability and corrosion resistance on the coated bond layer; It provides a method of regenerating the marine diesel engine crankcase corrosion portion comprising a.

In the present invention, the pretreatment process refers to the formation of grooves or troughs in order to increase the surface area of the coating layer after removal of the defects due to corrosion by cutting or polishing, and the grit ( grit) is a process of blasting (blasting) to form fine irregularities.

Here, the grit used for blasting is made of alumina or silicon carbide and used in the form of wire or powder, and the size of the grit is in the range of -14 +30 mesh, and is preferably blasted at an air pressure of 30-120 psi.

In the present invention, the bond layer coating process is a nickel-aluminum alloy or 60-98 wt% nickel chromium formed of 50-95.5 wt% nickel, 50-4.5 wt% aluminum and unavoidable impurities after processing irregularities on the surface of the defective portion. It is preferable to coat the composite powder consisting of the alloy and 2-40% by weight aluminum to a thickness of 50-200 μm by metal spraying.

On the other hand, the top coating layer coating process in the present invention is 1-15% by weight Mn, 0.3-15% by weight Ni, 10-25% by weight Cr, 0.05-0.5% by weight C, 0.01- 0.1 wt% P, 0.01-0.1 wt% S, 0.3-1.5 wt% Si, 1-5 wt% Mo, 60-87.33 wt% Fe It is desirable to coat the alloy containing other unavoidable impurities by metal spraying.

Herein, the metal spraying method used when coating the bond layer coating and the top coating layer of the present invention preferably uses any one of an electric arc, an oxygen-fuel flame, and a plasma flame as the heat source.

As described above, when the bond layer and the top coating layer are double coated by the metal spray method by the regeneration method according to the present invention, pores are generated on the surface or the inside of the coating layer. In the present invention, after the top coating layer is coated to seal the pores, the top coating layer is sealed using any one of a resin or aluminum paint sealer.

In addition, in the present invention, after the sealing process for sealing the pores, in order to flatten the surface of the metal coating layer or the sealing layer, machining or grinding processing to facilitate the assembly of the recycled parts.

Hereinafter, with reference to the accompanying drawings will be described in detail a method for reproducing corrosion parts of a marine diesel engine according to the present invention.

The regeneration method of the present invention to be described below is described by taking a crank case which is an important component of a diesel engine, in particular, a marine diesel engine, but the technical idea of the present invention is not limited thereto. It can be interpreted to apply to all mechanical parts that can be regenerated by the metal spray coating method.

2 is a view showing the concept of a metal spray coating layer recycled by the present invention.

As illustrated in FIG. 2, the corrosion defects in the crankcase of the diesel engine are mainly generated in the crankcase part made of cast iron or a nonferrous alloy such as cast steel or aluminum. Therefore, in the method of regenerating corrosion parts of a diesel engine according to the present invention, the defect coating is first undercutted, and then the bond coating 20 and the top coating 23 are laminated in a double cut by a metal spraying method. The main feature is to spicy.

The present invention provides a pretreatment step for greatly removing corrosion defects and improving process efficiency of a subsequent step, and coating a bond layer 20 for improving adhesion between the top coating layer and the crankcase and buffering the difference in thermal expansion coefficient between the two metal layers. Process and the top coating layer 23 coating process excellent in machinability and corrosion resistance.

First, the pretreatment process according to the present invention consists of a defect removal process for removing corrosion defects and a pretreatment process for increasing the bonding strength of the subsequent coating layer on the processed surface from which the defects are removed.

In the defect elimination process, the inner part of the crankcase 10 in which the corrosion of the upper liner 13 and the jaw assembly 17 has a high occurrence of corrosion is cut off by machining by a boring machine, a machine tool for boring or a grinder or a grinding machine. do. A groove or groove is then formed to increase the surface area at the bottom of the machined surface to increase the mechanical adhesion of subsequent coating layers.

The pretreatment process is a pretreatment of thermal spray coating, first of which removes foreign substances such as process oil or rust preventive oil used in the defect removal process, and then blasts the surface to be coated by using alumina or silicon carbide (SiC) grit. It is a process for forming fine irregularities. Here, the size of the alumina or silicon carbide grit is in the range of -14 +30 mesh or -10 +30 mesh, and the air pressure during blasting is 30-120 psi. After blasting, remove any dust or foreign matter remaining on the coated surface with compressed air or a brush.

The bond layer coating process according to the present invention is 50-200 for the purpose of improving the adhesion between the highly corrosion-resistant top coating metal layer and the crankcase to thermally coat the nickel-aluminum alloy layer in a subsequent process and buffer the difference in thermal expansion coefficient between the two metal layers. Coating to μm thickness. The composition of the coating material forming the bond layer is a nickel-aluminum alloy consisting of 50-95.5 wt% nickel, 50-4.5 wt% aluminum and other unavoidable impurities, but 60-98 wt% nickel chromium and 2-40 wt% aluminum. Nickel chromium alloy-aluminum composite powders are used, which are used in the form of wires or powders.

Here, the nickel-aluminum alloy used for the coating of the bond layer causes an exothermic reaction during thermal spraying, and forms a film having a dense structure, excellent oxidation resistance and thermal shock resistance. When the nickel-aluminum alloy wire reaches a certain temperature in the thermal spraying flame, a large amount of heat is generated as nickel and aluminum react to form nickel aluminide. The exothermic rebound heat generated at this time is transferred to the molten particles being injected at a high speed to improve the bonding properties of the coating. In addition, the nickel chromium alloy-aluminum composite powder has characteristics of excellent oxidation resistance and corrosion resistance. In this composite powder, nickel does not form carbides and does not increase its strength, but it has a role of making grains fine and increasing toughness, while chromium forms carbides to increase strength and hardness and to improve wear resistance. Aluminum serves to improve the oxidation resistance of the coating layer.

The bond layer is coated using a metal spray method, and the same effect can be obtained by using any one of an electric arc, an oxygen-fuel flame, and a plasma flame as a heat source for melting and depositing the thermal spray material on the crankcase surface.

The top coating layer coating process according to the present invention is a process for forming a highly corrosion-resistant metal layer by spraying a highly corrosion-resistant metal on the surface of the bond layer. The metal layer to be top-coated in this way should have excellent corrosion resistance because it is in direct contact with the crankcase cooling water, and should be processed to stage zero after metal spraying, and should have excellent machinability. Inseparable features are required. Highly corrosion-resistant materials suitable for these properties include 1-15% Mn, 0.3-15% Ni, 10-25% Cr, 0.05-0.5% C, 0.01-0.1% P, 0.01-0.1% S, Preference is given to alloys having a composition comprising 0.3-1.5 wt% Si, 1-5 wt% Mo, 60-87.33 wt% Fe and other unavoidable impurities. These highly corrosion-resistant spray materials are used in the form of wires or powders.

In addition, the top coating layer is coated using a metal spray method, and the heat source for melting and attaching the high corrosion resistant thermal spraying material forming the top coating layer to the surface of the bond coating layer is the same effect using any of electric arc, oxygen-fuel flame, and plasma flame. Can be obtained. Here, the coating thickness of the top coating layer is coated to the extent that all the defects removed, unlike the bond layer coating to a certain thickness coating.

The crankcase can be assembled and reused only by forming the top coating layer on the defect portion removed as described above, but by adding the finishing process described below to the thermal spray coating layer, the life of the regenerated crankcase can be further extended. . Such finishing processes include a sealing process and a finishing surface processing process.

In the sealing process according to the present invention, when the thermal spray coating layer is formed by the metal spray method, 1-20% of pores are present in the thermal spray coating layer. This process is performed for the purpose of sealing it. In the sealing process, such pores are sealed or coated using a sealing material. Resins and aluminum paint are used as the sealer used at this time. Resins used as sealers include silicone resins, phenolic resins, polyester resins, epoxy polyamide resins, epoxy resins, and urethane resins. Resin), it is preferable to use any one of the water based Alkyd Resin.

The sealer used for pore sealing may apply a spray coating layer with a brush or spray, or crank case may be deposited on the sealer to infiltrate the sealer into the pores to seal the pores. Therefore, the process of coating the sealer is selected in consideration of the physical properties of the sealer to be used.

Surface treatment process according to the present invention is to precisely assemble the cylinder liner 13 to the crank case 10 with the thermal spray coating layer is formed by the machining or grinding the surface of the thermal spray coating layer as it is or is sealed on the thermal spray coating layer It is a flattening process.

As described above, the present invention simplifies the operation by regenerating and repairing the cooling water corrosion portion of the marine diesel engine crankcase by the metal spraying method, and is particularly resistant to the cooling water use conditions by the coating material, and thus the same as that of the original product. There is an advantage that can give the above physical properties.

In addition, the present invention can reliably reproduce the local corrosion defects of the crankcase because of these advantages, and the regeneration method according to the present invention can be continuously repaired or repeated repairs to extend the life of the crankcase to the same or more than the new product. It can work.

Furthermore, when the crankcase is regenerated by the regeneration method according to the present invention, there is no fall out of the bush or leakage of the coolant, thereby enabling the marine diesel engine to be used for a long time and stably.

Claims (12)

In the method of regenerating and repairing the corrosion defects generated by the cooling water of the marine diesel engine crankcase, A defect removal step of removing the corrosion defect portion by mechanical processing; A pretreatment step of increasing the adhesive surface area by mechanical processing on the corrosion defect portion from which the defect is removed; and Bond layer coating step to improve the adhesion between the subsequent metal coating layer and the base metal to the pre-treated bonded portion and buffer the difference in coefficient of thermal expansion between the two metal layers; And Top coating layer coating step of excellent machinability and corrosion resistance on the coated bond layer; Recycling method of marine diesel engine crankcase corrosion part including. The method of claim 1, wherein the pretreatment step includes forming grooves or troughs to increase the surface area of the removed defective portion. 3. The regeneration of the marine diesel engine crankcase corrosion portion as claimed in claim 2, further comprising the step of blasting a grit on the surface of the defect portion in which the groove or the trough is formed to form fine roughness. Way. 4. The method of claim 3, wherein the grit is made of alumina or silicon carbide. 5. The method of claim 3 or 4, wherein the size of the grit is in the range of -14 +30 mesh and is blasted at an air pressure of 30-120 psi. The nickel-aluminum alloy or 60-98 wt% nickel chromium according to claim 1, wherein the step of coating the bond layer comprises 50-95.5 wt% nickel, 50-4.5 wt% aluminum and unavoidable impurities on the pretreated defect surface. A method of reclaiming corrosion of a marine diesel engine crankcase corrosion part, characterized by coating a composite powder consisting of an alloy and 2-40% by weight aluminum by metal spraying. The method of claim 6, wherein the bond layer coating is coated with a thickness of 50-200㎛. The method of claim 6, wherein the metal spraying method of the coating of the bond layer comprises any one of an electric arc, an oxygen-fuel flame, and a plasma flame as a heat source thereof. The method of claim 1, 2, 3, 4, 6 or 7, wherein the top coating layer coating step is 1-15 weight on the surface of the bond layer coated with the bond layer % Mn, 0.3-15 wt% Ni, 10-25 wt% Cr, 0.05-0.5 wt% C, 0.01-0.1 wt% P, 0.01-0.1 wt% S, 0.3-1.5 wt% Si, 1-5 wt% Mo, 60-87.33% by weight Fe Recycling method of marine diesel engine crankcase corrosion part characterized by coating the alloy containing other unavoidable impurities by metal spraying method. 10. The method of claim 9, wherein the metal spraying method of the top coating layer coating step uses any one of an electric arc, an oxygen-fuel flame, and a plasma flame as a heat source thereof. The method of claim 1, wherein after coating the top coating layer, a silicone resin, a phenol resin, a polyester resin, an epoxy polyamide resin, and an epoxy resin are coated. ), A sealing step of sealing pores existing in or on the surface of the coating layer by using a sealer of any one of resins of the urethane resin, water based alkyd resin, or aluminum paint. Recycling method of the marine diesel engine crankcase corrosion portion further comprising a. 12. The method of claim 1 or 11, further comprising a machining or grinding step of planarizing the surface of the coating layer or the sealing layer after the sealing step.