KR101073494B1 - Method of manufacturing a nozzle for a fuel valve in a diesel engine and a nozzle - Google Patents

Abstract

In a mould (13) a corrosion-resistant first alloy (10) is arranged at least in an outer area which is to constitute the outer surface of a nozzle around the nozzle bores (4). A second alloy (11) is used in another area of the nozzle. The materials in the mould are treated by isostatic pressing into a consolidated material. The boundary area between the two alloys (10, 11) is free of cracks.

Description

Method of manufacturing a nozzle for a fuel valve of a diesel engine, and a nozzle manufactured by the method {a method of manufacturing a nozzle for a fuel valve in a diesel engine, and a nozzle}

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a nozzle for fuel valves in diesel engines, particularly two-stroke crosshead engines, wherein the first component of the first alloy of a corrosion resistant alloy forms the outer surface of the nozzle around the nozzle bore. Is placed in the mold.

This method, in which the mold is subjected to HIP (Hot Isostatic Pressing) after filling the first component of the first alloy as a whole of the nozzle, shows a fairly good performance in nozzle strength and corrosion resistance at the nozzle. This is the method already described at 24865. In addition, if the shape around the nozzle bore is processed precisely, the fuel can be well sprayed. In this Hot Isostatic Pressing, the finely powdered powder is consolidated into the entire nozzle blank at high temperature and high pressure, and the nozzle blanks produced are balanced to maintain a very finely powdered alloy structure. do.

EP 0 982 493 A1 describes a fuel valve with a nozzle extending beyond the main valve seat over the valve housing and over the slider guide. These parts of the fuel valve are formed of steel which provides an indispensable hardness for valve seats and the like. At the lowermost side of the nozzle, a corrosion resistant coating is formed by laser welding, plasma welding or thermal powder spray, so that all or part of the molten material is combined with steel. The material of the bonding region has the property of causing the corrosion resistant alloy to come off after work or with respect to hardness. In this process, the nozzles are exposed to strong periodic thermal loads that create a risk of lowering the adhesion of the corrosion resistant alloy.

It is an object of the present invention to produce nozzles with long lifetimes.

In this regard, the above-mentioned nozzle manufacturing method according to the present invention is characterized in that the second component of the second alloy is disposed in the inner region of the mold, and the disposed component is a minute of the boundary region between the first alloy and the second alloy. It is characterized in that it is processed by a crack of nozzle blank.

By using the second alloy in the nozzle, a change occurs in the structure of the nozzle, and a change in the material or the structure negatively affects the life, but the life of the nozzle is improved. Since there are no minute cracks in the boundary region between the two alloys, the nozzle life is improved. The reinforcement (unification) of the different materials by isostatic pressing results in diffusion-controlled reinforcements without the appropriate kind of boundary regions known to apply molten material onto solid materials. Although nozzles of the type known as EP 0 982 493 A1 are heat-treated to a more uniform hardness before use, fine cracks occur in the thin and very strong melt-based mixing zone and steel heat-affecting zone immediately after application. The diffusion-controlled solidification operation according to the invention does not form any melt-based mixing zone while maintaining the heat-affecting zone. By preventing the occurrence of minute cracks in the transition between two different components, it is possible to eliminate the root cause of fatigue breakdown in the nozzle, thereby significantly improving the life of the nozzle. Due to the diffusion-controlled solidification operation, the risk of binding failure between two different components is reduced.

To further improve service life, the second component of the second alloy has better fatigue strength than the corrosion resistant first alloy of the finished nozzle. In addition to the normal thermal load applied to the nozzle, in order to more precisely control the fuel injection of the diesel engine, thereby improving fuel combustion and reducing the generation of pollutants, a significant increase in the fatigue load is higher than that applied. Fatigue strength is an important factor in the life of the nozzle because it is expected that the use of injection pressure and rapid pressure vibration will occur continuously.

When at least the corrosion resistant alloy comprises at least 0.6% Al, an oxygen-limited diffusion barrier is preferably used between the first component of the first alloy and the second component of the second alloy before the isostatic compression molding. The oxygen-limited diffusion barrier interacts with the diffusion oxygen discharged from the second alloy to the first alloy and reacts with the alloying component or undesirable Al. For example, oxygen is present in the dissolved state in the second alloy and is released at the time of dissolving the oxide in the second alloy while heating the components. The small amount of oxygen of several ppm causes other undesirable precipitation in the boundary region between the two alloys which causes precipitation of aluminum oxide or lowers the overall fatigue strength of the nozzle.

The diffusion barrier prevents harmful diffusion of oxygen such that the nozzle maintains high fatigue strength. Diffusion barriers may be used where the alloy contains Al exactly 0.6% or less. For example, the positive effect of the barrier can be obtained in aluminum alloys containing 0.1 to 0.5% Al. The barrier can be used if the alloy is exposed to the risk of metallurgical processes causing precipitation of intermetallic compounds, undesirable precipitates such as carbides, oxides or aluminum oxides. The diffusion barrier has a limited effect in transporting alloying components that are different from oxygen from one material to another. In particular, small constituents, such as carbon and boron, in their free form diffuse from the alloy of the higher content to the alloy of the lower content. By using diffusion barriers, it is possible to select alloying components that are independent of the components of other alloys. By limiting the carbon component of the second component of the second alloy, for example in a nozzle of high hardness, the second component of the second alloy reduces the tendency to cure cracks in the area of the nozzle of complex shapes such as nozzle bores. It will show its advantages.

For example, nickel and copper are suitable for forming a dense and stable coating in connection with a corrosion resistant alloy suitable for use as a nozzle material, so such diffusion barriers are formed of nickel, copper, or nickel alloys. Optionally a cobalt coating, cobalt alloy or chromium coating may be considered.

The nozzle manufacturing process can be simplified by placing a diffusion barrier on the inner face of the member prefabricated with the first component of the first alloy or on the outer face prefabricated with the second component of the second alloy. The prefabricated member acts as a carrier of the diffusion barrier until all the materials are placed in the mold and the isostatic compression molding process is performed and the material is reinforced. At the same time, due to the prefabricated member, the member is compressed because it is used as a holder for supporting a particulate starting material filled into or around the member of the mold or laminated together with other prefabricated members. Before the mold is filled quickly and easily.

In the latter case, the prefabricated member preferably consists of the first component of the first alloy and is filled with the particulate starting material of the second alloy. At the manufacturing stage, this provides the advantage that the mold can be filled quickly. At the same time, the second component of the second alloy is produced by powder metallurgy, so that a homogeneous structure exhibiting a particularly preferred fatigue degree can be obtained.

If a prefabricated member of the first alloy is used, it is preferably cast or manufactured by powder metallurgy into a bowl-like or tubular wall which forms a part of the mold to be pressed into a uniform state. Using prefabricated components, such as molds, the prefabricated components become part of the finished blank, thus eliminating or simplifying subsequent processes of removing the mold from the manufactured blank.

In another embodiment of the manufacturing method according to the invention, the core member preformed with the second component of the second alloy is placed inside a mold in which the powder of the first alloy is arranged before the isostatic compression molding process is performed. Since at least a portion of the second component of the second alloy is preformed, the core member is used to control the placement of the powder of the first alloy. The powder is disposed immediately adjacent to the core member without the risk of mixing the powder from the first alloy and the second alloy. The preformed core member makes it possible to place the particulate starting component in exactly the desired position.

A member preformed with the first component of the first alloy and / or a member preformed with the second component of the second alloy can be, for example, CIP (Cold Isostatic Pressin: Cold Isostatic Pressin) followed by a machining or extrusion process. Can be prepared from the particulate starting component by a) treatment or HIP treatment process or by sintering with a subsequent pressurization process so that the member has the desired equilibrium structure. It is also possible to use a plurality of cast iron or soft iron materials whose properties are improved by isostatic compression molding.

The isostatic compression molding process may be a suitable HIP (hot isostatic compression molding) process, which results in the reinforcing of the material by diffusion while preventing the particles from growing, so that one or more materials are solidified into agglomerated material without melting. It is possible to maintain a finely powdered structure from the fact that it is made of a powdered material. This isostatic compression molding process may be a CIP treatment process where compression occurs at a significantly lower temperature than HIP treatment.

In another aspect, the present invention relates to a nozzle for a fuel valve of a diesel engine, in particular a two-stroke crosshead engine, the invention having a central longitudinal channel in communication with a plurality of nozzle bores open on an outer side of the nozzle. The nozzle is made of at least a corrosion resistant first alloy in an outer region around the nozzle bore, and in a region different from the outer region of the nozzle bore.

As the length of the nozzle is improved, as already mentioned in connection with the description of the above-described method according to the first embodiment of the present invention, the nozzle is minutely cracked in the component of the boundary region between the first alloy and the second alloy. Characterized in that there is no structure.

For the effects and advantages achieved by the nozzle according to the invention, reference is made to the description of the method according to the first embodiment of the invention.

As a preferred embodiment, the second alloy has a higher fatigue strength than the corrosion resistant first alloy, which can achieve a lifespan above the aforementioned life.

In one embodiment, an oxygen-limiting diffusion barrier is installed at the nozzle between the first alloy and the second alloy. The diffusion barrier makes it possible to analyze the corrosion resistant first alloy based on the desired characteristics and to determine the conditions for the production of such alloy without considering whether the alloy reacts negatively with the components of the second alloy. Similarly, analyzing the second alloy can be determined without considering the components of the first alloy.

The second alloy is made of powder metallurgy, whereby the performance is improved as compared to the component produced alone by melting the desired member.

In a preferred embodiment, the first alloy is a nickel based alloy and the second alloy is an iron-based alloy. Since many nozzle bores are located in small spaces and are divided by central channels in the longitudinal direction at different angles, the iron-based alloy used inside the nozzle provides high strength to areas of nozzles with complex shapes.

Nickel-based alloys are sensitive to carbon formation and thus only have a limited carbon component of, for example, 0.6% or less by weight. Typical iron-based alloys with high fatigue strength have high carbon content of up to several percent by weight. If necessary, the iron-based alloy is selected to have less carbon at the operating temperature of the nozzle than the nickel-based alloy. The component of the alloy formed of carbide in the iron-based alloy is selected such that, for example, the melting temperature of carbon is above the operating temperature of the nozzle and above the HIP temperature when the nozzle is manufactured by HIP treatment. Free carbon is prevented from being released by the dissolved carbides. In addition, a strong carbide former is selected as the alloying component to help catch and fix any free carbon.

The nozzle is suitably designated as a separation unit located in the fuel valve of the continuous spindle guide carrying the main valve seat of the fuel valve. In such a structure, the nozzle is not affected or minimally affected by the rather large stresses occurring in the main valve seat. At the time of nozzle replacement, this replacement operation is limited to small parts which mainly constitute part of the fuel valve protruding into the combustion chamber.

In another embodiment, the second alloy is advantageous in terms of cost in addition to being advantageous in strength if the nozzle comprises at least 70% of the aggregated mass, so that the second alloy is less expensive than the first alloy.

The invention will be explained in more detail below with reference to the drawings.

1 is a cross-sectional view in the longitudinal direction viewed through a nozzle mounted to a lower end of a fuel valve.

2 through 7 are cross-sectional views of molds filled with various powders used to HIP the nozzles.

1 shows a nozzle (indicated by reference numeral 1) of a fuel valve of a four-stroke crosshead engine, preferably a two-stroke crosshead engine, having one or more fuel valves in each cylinder. Because two-stroke crosshead engines operate on heavy fuels containing sulfur, they require stringent conditions in terms of nozzle length.

The nozzle protrudes through the central hole at the end of the valve housing 2, and the annular surface 3 is compressed against the corresponding contact surface of the cylinder cover or cylinder liner, shown in broken lines, to provide a nozzle with a nozzle bore 4. The tip of the may protrude into the combustion chamber (A), and when the fuel valve is opened to inject fuel. The fuel valve is provided with a valve slider 5 with a valve seat 7 and a valve needle 6 located at the lower end of the slider guide 8, as in the valve structure shown. The valve slider is compressed downward with respect to the upward surface at the nozzle 1.

The nozzle has a longitudinal channel 9 centered from the nozzle bore with the nozzle bore 4 running on the outer side of the nozzle. The nozzle consists of a first alloy 10 composed of a corrosion resistant first component and a second alloy 11 composed of a second component. The first alloy forms at least the outermost part of the nozzle in the region around the nozzle hole and extends upward to form the outer surface of the nozzle over the entire portion of the nozzle protruding from the valve housing 2.

The first component of the corrosion resistant first alloy consists of a particulate starting component, or is produced, for example, by the method of casting. Alloy applicable as the first alloy. For example, 15 to 30% Cr, 0.02 to 0.55% C, and optionally 0 to 15% W, 0 to 8% Al, 0, calculated as weight percent excluding common impurities To 5% Ti, 0 to 20% Co, 0 to 2% Hf, 0 to 5% Nb and / or Ta, 0 to 35% Mo, 0 to 10% Si, 0 to 1.5% It is a nickel-based alloy containing any one or more of Y and 0 to 20% of Fe. Such alloys contain inevitable impurities, the remainder being nickel. Typical examples of such alloys have a composition of 23% Cr, 7% W, 5.6% Al, 1% Si, 0.5% C, 0.4% Y. This HIP treated alloy has a fatigue strength σ _A of about ± 450 MPa.

Nickel-based alloys include 35 to 60% Cr, 0.02 to 0.55% C, optionally 0 to 1.0% Si, 0 to 5.0% Mn, calculated in weight percent and excluding common impurities 0-5.0% Mo and / or W, 0-0.5% or less B, 0-8.0% Al, 0-1.5% Ti, 0-0.2% Zr, 0-3.0% Nb, 0-max One or more of 2% Hf, 0-1% N, 0-1.5% Y, up to 5.0% Co and Fe. Such alloys inevitably contain impurities, with the remainder being Ni. These materials have high resistance to both high fatigue strength and high temperature corrosion or erosion from fuel.

Examples of the alloy used as the corrosion-resistant first alloy material is shown in Table 1 below.                 

TABLE 1

alloy Approximate component (% by weight) free of impurities Thermal expansion coefficient (10 ^-6 / ℃) Inconel 625 0.1% C, 22% Cr, 9% Mo, 3.5% Nb, 0.4% Al, 0.4% Ti, Remnant Ni 13.9 Inconel 617 0.07% C, 22% Cr, 12.5% Co, 9% Mo, 1.2% Al, 0.6% Ti, Remnant Ni 13.8 Inconel 725 0.03% C, 21% Cr, 8% Mo, 3.5% Nb, 1.4% Ti, 9% Fe, Remnant Ni 14.1 Inconel 657 0.1% C, 50% Cr, 1.5% Nb, Remnant Ni 13.4 Hostelly B2 0.01% C, 28% Mo, 1% Cr, 2% Fe, 1% Co, Rest Ni 11.6 Hastelloy G30 0.03% C, 30% Cr, 15% Fe, 5% Co, 5.5% Mo, 1.5% Nb, 2% Cu, 2.5% W, Rest Ni 15.2

The coefficient of thermal expansion is referred to as the average linear coefficient of thermal expansion when heated to 20 degrees Celsius to 500 degrees Celsius, in other words, to 500 degrees Celsius. It is preferable that the first alloy has almost the same coefficient of thermal expansion as the second alloy. Optionally, the first alloy has a higher coefficient of thermal expansion than the second alloy such that compressive stress occurs in the central portion of the nozzle in connection with cooling to 20 degrees from the HIP temperature.

Cobalt-based alloys, such as Celsit 50-P, may also be used; under HIP treatment conditions, these alloys have a fatigue strength (σ _A ) around ± 150 MPa, which is why such alloys are not preferred. .

As an alloy component for the second alloy, AISI H13 tool steel comprising 0.4% C, 1.0% Si, 0.4% Mn, 5.2% Cr, 1% V, 1.3% Mo, Fe as the remaining components, or AISI H19 tool steel containing 0.45% C, 0.4% Si, 0.4% Mn, 4.5% Co, 4.5% Cr, 0.5% Mo, 2% V, 4.5% W, Fe as remainder Or tool steels of the USA thru research, including 0.5% C, 4.5% Cr, 1% V, 2.75% Mo, 2% W, 0.4% Si, 0.5% Mn, Fe as the remaining components Preferred are CPM1V, 0.8% C, 7.5% Cr, 2.5% V, 1.3% Mo, 0.9% Si, 0.4% Mn, and Fe steel with Fe as the remaining components.

Tool steels are produced by powder metallurgy, which is a finely powdered isotropic powder with a very precise structure, so that a carbide network is avoided despite the high proportion of added alloying components. With the press-atomic molten alloy at cold temperature, the carbides are extremely small and are uniformly dissipated.

Examples of alloying materials for the first alloy are shown in Table 2 below, in which the coefficient of thermal expansion is mentioned in the same manner as in Table 1.

Table 2

alloy Approximate component (% by weight) free of impurities Thermal expansion coefficient (10 ^-6 / ℃) AISI H11 0.4% C, 5% Cr, 1.3% Mo, 0.5% V, Remnant Fe 13.1 AISI H21 0.3% C, 3.5% Cr, 9.5% W, 0.5% V, rest Fe 12.8 AISI A8 0.5% C, 5% Cr, 1.4% Mo, 1.2% W, Remnant Fe 12.1 AISI M2 0.9% C, 4.3% Cr, 5% Mo, 6% W, 2% V, rest Fe 12.3 AISI O1 0.9% C, 0.5% Cr, 0.5% W, rest Fe 13.3

For certain tool steels, the fatigue strength is controlled by the heat treatment given to the nozzle blank. After isostatic compression molding the nozzle blank, the outer shape and the inner shape of the nozzle blank are completed. This means that the longitudinal center channel and the nozzle bore are machined into blanks, wherein the outer surface of the blank can be turned or ground to its final shape.

When the shape machining is finished, the nozzle blank undergoes a heat treatment in which the second alloy hardens to the appropriate hardness. For example, this curing is carried out in a temperature range of 1000 degrees Celsius to 1100 degrees Celsius for an immersion time of 10 to 40 minutes. The final heat treatment is then carried out in the form of one or more tempering treatments, which is important in that it determines the fatigue strength of the finished nozzle. For example, tempering is performed by immersion for 2 hours in the temperature range of 450 degrees Celsius to 600 degrees Celsius. It is preferable to temporally double or triple at two or three time intervals of two hours. The tool steel described above has a fatigue strength σ _A around ± 500-900 MPa in the finished nozzle. Fatigue strength σ _A is at least ± 750 MPa. At the same time, the tool steel preferably has high wear resistance and hardness.

In the first alloy and the second alloy, the powder preferably has a size in the range of 0 to 1000 micrometers.

How the nozzle blank is treated by isostatic pressing is illustrated below.

2 shows a preformed core member 12 inserted into a mold 13, which consists of a bottom panel 14, a side wall 15, a cover 16, and a filling nozzle 17. The core member is made of a second alloy and is first sintered with each other and then formed by cold compression with a so-called green blank. The core member is made by high speed powder compaction or CIP or HIP treatment. The core member is formed by a method for general tool steel, and may be ESR (Electro Slag Refined) recasting. The core member has a head portion 18 having a diameter slightly larger than the body portion projecting upward into the mold 13. The body portion extends beyond the area around the central channel 9 of the finished nozzle. The body portion extends to a predetermined distance from the nozzle bore or, as shown in FIG. 1, extends inside the nozzle to cover the entire central channel. In the latter case, the nozzle bore passes through the second alloy in the region around the central channel and through the outermost first alloy of the nozzle.

The side wall 15 is joined below the head portion 18 and has a smaller diameter and becomes narrower toward the top. In the body portion, the side walls are at a distance corresponding to the desired thickness of the corrosion resistant first alloy. The circular bottom panel 14 is welded along the entire circumference with the bottom rim of the side wall 15. Similarly, the cover 16 is welded to the upper rim of the side wall and the filling nozzle is welded to the top surface of the cover.

The finely powdered powder of the first alloy 10 is filled into the cavity around the core member 12 through the filling nozzle 17, and the mold with powder is vibrated, if necessary, the mold It is emptied and closed in such a way that it is compressed at the filling nozzle.

The mold is then placed in a furnace and the chamber of the furnace is pumped to a pressure of about 200 bar with an inert gas such as argon and heated to a temperature range of 1000 to 1300 degrees Celsius, in particular 1500 degrees Celsius. At the same time, by this heating process, the pressure inside the chamber of the furnace rises to about 900 bar to 1100 bar. This temperature and pressure are maintained for 4 to 8 hours during which the components inside the mold are tightly reinforced to become holes-free objects.

After cooling, the mold is removed from the HIP treated blank. For example, the mold used consists of steel or glass material. In the case of glass, the above-mentioned welding is to heat and melt glass.

The annealed nozzle blanks are finished, for example, by turning or boring processes, which blanks are relaxed, hardened and tempered. As a result of the HIP treatment at high temperature, if the heat treatment is performed at a temperature lower than the HIP temperature, the heat treatment of the nozzle is performed without growing particles in the material. This feature is advantageous because larger particles generate lower fatigue stresses.

The lifetime of the nozzle according to the invention is long because there are no minute cracks in the transition region between the two materials. Fine cracks are cracks of a single crystal particle or cracks extending through several crystal particles. Generally, the cracks have a size of 0.05 mm to 0.5 mm. Cracks of 0.05 mm or less are negligible. If minute cracks occur in the nozzle, cracks occur in the nozzle. The reason is that the cracks caused by the above-described heat affected zones or bonding errors do not affect only a few particles, but over large sections. The presence of fine cracks is confirmed by examining several stress exposed boundary areas between the two alloys at the nozzle. If there are no minute cracks in the most exposed areas, it can be determined that there are no minute cracks in the boundary region throughout the nozzle.

For convenience, the same reference numerals are used for parts having the same functions as described above in the following description of other embodiments.

3 shows the shape of a mold 13 suitable for producing many nozzles in the same mold. The side wall 15 is cylindrical in shape with an inner diameter corresponding to the outer diameter of the head portion 18. The thickness of the first alloy is controlled by placing the cylindrical fill pipe 21 around the body portion before filling the pipe with powder. By forming the side wall 15 larger than shown in the figure, the first core member 12 and its associated diffusion barrier 24 and the filling pipe 21 are disposed inside the side wall prior to installing the cover 16. The powder is filled into the inside of the filling pipe at its upper edge. The next core member, barrier 24 powder with pipe 21 can be placed on top of the first one, and the entire mold is closed by installing a cover 16 until the side wall 15 is filled. . HIP processing is then performed as described above.

The diffusion barrier 24 is disposed on the outer surface of the body portion 19 and the upward surface of the head portion 19. The barrier is coated on the preformed core member by other surface treatment methods such as electrolyte deposition or plating. For example, the barrier consists of nickel, copper, cobalt or nickel-phosphorus. Optionally, the coating is achieved by spraying or by foiling a thin material around the body portion 19 of a predetermined material of pure metal such as nickel, cobalt or copper. The barrier has a thickness in the range of 5 to 400 micrometers, preferably 10 to 100 micrometers.

4 shows another structure in which the side wall 15 is cylindrical and welded to the bottom rim of the shoulder of the head portion 18. This structure makes the mold less expensive. In connection with the precise machining of the nozzle after the HIP treatment, the weld with the heat-affecting zone is removed by turning. The preformed core member is for example made by a prior HIP treatment or CIP (Cold Isostatic Pressing) treatment, but no welding is applied to the material.

FIG. 5 shows a structure in which a cylindrical tubular wall 22 of the first alloy is disposed around the body portion 19. The inner diameter of the pipe is larger than the outer diameter of the body portion, so that the diffusion barrier 24 is not damaged during assembly. The wall 22 is made by powder metallurgy, but is made of ordinary pipes, in particular seamless pipes. After the powder of the first alloy is filled inside the wall, the HIP treatment as described above is performed except that the wall 22 remains on the core member to become part of the nozzle blank.

FIG. 6 shows a structure in which the walls 22 of the first alloy are bowl-shaped and provided with a diffusion barrier 24. After mounting the cover 16, the mold is filled with powder of the second alloy and the HIP treatment is performed in the same manner as described above except that the wall 22 remains inside the HIPed interior of the nozzle blank. Is performed.

The corrosion resistant first alloy and the second alloy 11 and the diffusion barrier 23 in the form of a wall 22 are made of two prefabricated members with a barrier located on one or the other member, the members being shown in FIG. As shown in Fig. 6, inserted toward each other, the cover 16 is mounted so that the mold is emptied and closed, and the HIP process is performed as described above. In this case, the HIP treatment does not involve the step of actually strengthening the particulate starting component since the members are already manufactured as already described above, but due to the HIP treatment the member is solidified into an adhesive blank by diffusion bonding at the interface.

7 shows an embodiment in which the mold is internally divided by a panel partition 23 extending at the interface between the first and second alloys. The panel partition 23 is formed of a first alloy or a second alloy. The panel partition 23 may be an oxygen-limited diffusion barrier made of a third material. Since the panel partition is relatively thick, components from the second alloy cannot diffuse into the first alloy.

The bottom panel is equipped with a filling nozzle 17 for filling powder. First, when one powder is filled through the filling nozzle, air is discharged and the nozzle is closed. Then, the mold is turned upside down so that the second powder is filled through the second nozzle, and the air is discharged from the second chamber. Then, the HIP process as described above is performed.

The nozzle may have a structure more than that shown in FIG. 1. The valve slider has a second blocking member for blocking the nozzle bore 4 in the fuel channel 9. The second blocking member is preferably made of tool steel as it slides along the inner surface of the longitudinal channel of tool steel. This is due to the fact that the two tool steels work well together. It is also possible to seat the main valve on the nozzle, so that the fuel channel under the valve seat is at a minimum volume. In addition, the nozzle bore is oriented not only on one side of the nozzle, but also on both sides or the other side of the nozzle, and dissipates along the entire periphery of the nozzle.

The preformed core member of the second alloy and / or the preformed bowl or pipe-shaped wall of the first alloy is produced prior to particulate starting components such as molds or soft iron materials. The temperature is controlled during the HIP treatment to allow the second component of the second alloy to cure and temper or to be annealed or directly related to the HIP treatment to omit subsequent heat treatment steps.

Detailed descriptions of various embodiments may be combined with new embodiments. It is possible to mix the first alloy or the second alloy of various powder sizes, and powders of a plurality of different metal alloys are used in the form as described above. In addition, it is possible to further mix the powder of the ceramic material in order to obtain the insulation effect. For example, the powder of ceramic material is placed in a layer of short distance from the tip of the nozzle. The ceramic powder is covered by the powder of the first corrosion resistant alloy. Various powders mixed in stages may also be used. In filling the mold prior to the HIP process, it is possible to install a screen of ceramic material on a powder of a first alloy, such as, for example, a powder placed on the body 19 of FIG. 2. The powder of the first alloy is disposed on top of the screen so that the outermost part of the nozzle consists of a corrosion resistant component.

Claims (23)

In a method of manufacturing a nozzle for a fuel valve of a diesel engine, the first component of the corrosion resistant first alloy is disposed in a mold in an outer region forming an outer surface of the nozzle around the nozzle bore. A second component of the second alloy is disposed in the mold of the inner region, wherein the disposed components are subjected to isostatic compression molding to be reinforced with nozzle blanks without cracking at the boundary region between the first alloy and the second alloy. Nozzle manufacturing method. The method of claim 1, And the second component of the second alloy has a higher fatigue strength than the corrosion resistant first alloy of the finished nozzle. The method of claim 1, And an oxygen-limited diffusion barrier is used between the first component of the first alloy and the second component of the second alloy before the isostatic compression molding step. The method of claim 3, wherein The diffusion barrier is a nozzle manufacturing method, characterized in that made of nickel, copper, or nickel alloy. The method of claim 3, wherein The diffusion barrier is disposed on the inner side of the member prefabricated with the first component of the first alloy or on the outer side of the member prefabricated with the second component of the second alloy. The method of claim 1, The isostatic compression molding is a nozzle manufacturing method characterized in that the hot isostatic pressing (HIP) process. 7. The method according to any one of claims 1 to 6, And a member prefabricated with the first component of the first alloy is filled with a particulate starting material of the second alloy. The method of claim 7, wherein A member prefabricated with the first component of the first alloy is cast or produced by powder metallurgy into a wall forming a part of a mold used for isostatic compression molding. The method of claim 7, wherein And a member prefabricated with the first component of the first alloy is made from a particulate starting component. 7. The method according to any one of claims 1 to 6, And a core member preformed with a second component of the second alloy is placed in a mold in which the particulate starting component of the first alloy is placed before isostatic compression molding is performed. 11. The method of claim 10, And wherein said core member preformed with a second component of said second alloy is made from a particulate starting component. A central longitudinal channel in communication with a plurality of nozzle bores that open on the outer side of the nozzle, the outer region around the nozzle bore being made of a first corrosion resistant first alloy and a region other than the outer region of the second alloy In the nozzle for the fuel valve of the diesel engine is made by the nozzle manufacturing method of claim 1, The fuel valve nozzle, characterized in that the component of the boundary region between the first alloy and the second alloy has a crack-free structure. 13. The method of claim 12, And the second alloy has a higher fatigue strength than the corrosion-resistant first alloy. 13. The method of claim 12, A nozzle for a fuel valve, characterized in that the nozzle between the first alloy and the second alloy is provided with an oxygen-limited diffusion barrier. 13. The method of claim 12, And the second alloy is made by powder metallurgy. The method according to any one of claims 12 to 15, And the first alloy is a nickel-based alloy and the second alloy is an iron-based alloy. The method according to any one of claims 12 to 15, And the nozzle is a separate unit disposed in a fuel valve in front of the spindle guide on which the main valve seat of the fuel valve is mounted. The method of claim 17, And the second alloy is 70% or more of the total mass of the nozzle. The method according to any one of claims 12 to 15, The fatigue strength σ _A of the second alloy is ± 750 MPa or more. The method according to any one of claims 12 to 15, And the nozzle comprises an insulating ceramic material covered with the first alloy. The method of claim 16, And the nozzle is a separate unit disposed in the fuel valve of the spindle guide on which the main valve seat of the fuel valve is mounted. The method of claim 7, wherein The member pre-made with the first component of the first alloy, a) powder compaction process, b) powder compaction process followed by processing process, c) powder compaction process followed by extrusion process, d) CIP treatment process, e) CIP treatment process followed by machining process, f) CIP treatment process followed by extrusion process, g) HIP treatment process, h) HIP treatment process followed by processing process, i) HIP treatment process followed by extrusion process, or j) sintering process with subsequent compression process Nozzle manufacturing method characterized in that it is produced by one of the processes. The method of claim 11, The member prefabricated with the second component of the second alloy is a) powder compaction process, b) powder compaction process followed by processing process, c) powder compaction process followed by extrusion process, d) CIP treatment process, e) CIP treatment process followed by machining process, f) CIP treatment process followed by extrusion process, g) HIP treatment process, h) HIP treatment process followed by processing process, i) HIP treatment process followed by extrusion process, or j) sintering process with subsequent compression process Nozzle manufacturing method characterized in that it is produced by one of the processes.

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