KR20120000929A - Manufacturing method of fuel pump plange for ship engine using special hot tool steel dh32 or skd7 - Google Patents

Abstract

PURPOSE: A manufacturing method of a fuel pump plunger for a ship engine using DH32 or SKD7 hot-work tool steel is provided to perform forging in the capacity of a press by remarkably reducing excessive forging loads and stress concentration. CONSTITUTION: A manufacturing method of a fuel pump plunger for a ship engine using DH32 or SKD7 hot-work tool steel is as follows. A DH32 or SKD7 material is cut in a cylindrical shape. The cut DH32 or SKD7 hot-work tool steel is molded to a preliminary molded product composed of an inclined part formed between first and second cylindrical units. A preliminary molded and forged product is produced by vertically driving the preliminary molded product.

Description

MANUFACTURING METHOD OF FUEL PUMP PLANGE FOR SHIP ENGINE USING SPECIAL HOT TOOL STEEL DH32 OR SKD7}

The present invention relates to a ship engine fuel pump plunger manufacturing method, and more specifically, to a ship engine fuel pump plunger of DH32 or SKD7 special hot-hole oral material can be implemented in a hot forging method ship engine using a DH32 or SKD7 special hot-hole oral cavity It relates to a fuel pump plunger manufacturing method.

Plunger, one of the core parts of the ship engine fuel pump, has a pair of wing parts on one side of the round bar in a symmetrical shape to form a cross (†) shape overall, and is manufactured using special hot tool steel of SKD7 type or DH32 And the round bar material is removed by machining to obtain the shape of the final product. Because of this, a large amount of material must be removed, so the loss of material due to processing is severe, and the productivity is low because a large processing time is required for processing.

1 is a plunger processing process diagram of a conventional marine engine fuel pump. Plunger (1), which is a part of fuel pump for ship engine, is a very important role that fuel pump controls and supplies fuel injection amount and fuel injection pressure to ship engine. Parts. The performance of the fuel pump greatly affects the performance of the ship engine, and the core components in the fuel pump are operated at high temperatures and pressures of up to 500 ° C, 1300 bar, and so are essential devices to strictly control the performance of the product. Therefore, the components of the fuel pump are thoroughly managed the production process of the material specification, processing method and heat treatment method to withstand high pressure and fatigue.

Plunger, which is one of the core parts requiring high strength and fatigue limit among the components of fuel pump, is manufactured using 7 kinds of SKD or special hot work of DH32, and the round rod material of φ120 * 320 is machined. After removal and roughing (12), after the heat treatment (QT) through a finishing process and a precision grinding process to obtain the shape (1) of the final product. However, the production method by machining requires a large amount of material to be removed and also requires a long processing time for processing, so the loss of material due to machining is severe and the productivity is low.

In order to solve this problem, it is preferable to manufacture the shape of the product by using the hot forging method, but a process technology for implementing a ship engine fuel pump plunger of a special hot oral cavity material such as DH32 or SKD7 by hot forging has not been developed yet. It is not true. This is because special hot work steels, such as DH32 or SKD7, are significantly less deformable at hot, so if the hot forging method of plain steel is used, the mold is damaged by high forging load and excessive stress concentration, which shortens the life of the mold and plunger wings. This is because there is a problem in that formability and forging of the forged product are deteriorated due to overlapping or fleshing of the parts.

The present invention is to solve the above problems, an object of the present invention is to manufacture a cross (†) -shaped marine engine fuel pump plunger using a special hot-hole oral cavity such as DH32 or SKD7 rather than a general steel material It provides a hot forging process technology that can significantly reduce the amount of processing, and further reduces excessive forging loads and stress concentrations when taking a hot forging method to prevent mold breakage and forging within the capacity of a given press. The present invention provides a method for manufacturing a ship engine fuel pump plunger using DH32 or SKD7 special hot hole orifice.

The above object of the present invention includes a cutting step of cutting the DH32 or SKD7 into a cylindrical shape; A first cylindrical portion having the cut cylindrical DH32 or SKD7 special hot-hole oral cavity formed in a cylindrical shape having a first diameter, a second cylindrical portion formed in a cylindrical shape having a second diameter smaller than the first diameter, and the first A preform forming step of forming a preform formed of an inclined portion formed at an angle of 10 ° to 30 ° between the first cylindrical portion and the second cylindrical portion; A blocker process step of forming a preformed forging by a hot open forging method in a direction perpendicular to the axis of the preform; A finisher process step of molding in a direction perpendicular to the axis of the preformed forging and hot forming in a hot forging method; A trimming process step of removing the flash to produce a marine engine fuel pump plunger, wherein in the preforming body generation step, the length of the second cylindrical portion is formed to be longer than the length of the first cylindrical portion, and the preform is 1 is a vessel engine fuel pump plunger manufacturing method using a DH32 or SKD7 special hot-hole oral cavity, wherein the first diameter of the cylindrical portion and the second diameter of the second cylindrical portion are formed to have a diameter difference in a range of 8 mm or more and 15 mm or less. Achievable through

According to the method of manufacturing a ship engine fuel pump plunger using the DH32 or SKD7 special hot hole oral cavity according to the present invention, in the manufacture of the plunger of the ship engine fuel pump by applying the special hot hole orifice DH32 or SKD7 material, It is possible to replace the shape obtained with the hot forging process, which can significantly reduce the amount of machining, and not only improve the saving effect of raw materials for obtaining the final product by more than 60%, but also the processing required for machining There is a remarkable effect that not only can reduce the time and the tool cost required for machining, but also can improve the productivity.

In addition, even in the case of applying the hot forging method in the manufacture of DH32 or SKD7 special hot-hole oral marine engine fuel pump plunger, it is possible to significantly reduce the forging load by forming and forging a preform of a specific shape, and to help the good filling of the forged product. It is possible to prevent overlapping of the plunger wing, generation of mold, and mold breakage, and the forging operation can be performed in a relatively small forging press.

1 is a plunger processing process diagram of a conventional marine engine fuel pump.
Figure 2 is a forged product shape of the plunger which is the final product by the hot forging production method of the present invention.
Figure 3 is a process diagram for forging a plunger using a special hot hole oral cavity (DH32, SKD7) as an embodiment according to the present invention.
4 is a schematic diagram of the process of FIG.
FIG. 5 is a detailed view of the preform in FIGS. 3 and 4.
Figure 6 is an embodiment according to the present invention, a three-dimensional simulation prediction result by a computer showing the deformation shape for the plunger forging process with or without a preform.
7 is a graph showing the forging load predicted in the plunger forging process with and without a preform as an embodiment according to the present invention.
Figure 8 is a photograph of the specimen shape by temperature of the preliminary test performed for the present invention.
9 is a structure photograph of a test piece according to the test temperature of FIG. 8.
10 is a graph showing the compression test load according to the test temperature.
Figure 11 is a structure of the forging according to the present invention and a photograph of the structure after forging heat treatment (QT).
12 is a stress analysis data showing the stress distribution and the numerical value applied to the blocker mold when the preform of the present invention is not applied.
13 is a stress analysis data showing the stress distribution and the numerical value applied to the blocker mold when the preform of the present invention is applied.

The ship engine fuel pump plunger manufacturing method using the DH32 or SKD7 special hot hole oral cavity according to the present invention inserts a preform forming process and designs the preform obtained through the preform forming process into a specific shape and adopts a hot open forging method. This paper presents the technical features that can be implemented in the hot forging method of the ship engine fuel pump plunger of DH32 or SKD7 special hot hole oral cavity.

Prior to the detailed description of the present invention, the present invention uses a special hot-hole oral cavity that is not significantly deformable in the hot, such as DH32 or SKD7, not a general steel material, a pair of wings are provided on one side of the round bar shape as a whole (cross) †) corresponds to a specialized process technology for the production of hot-forged products of the ship engine fuel pump plunger of the shaft type. Therefore, the content of the invention described and described in the present invention is different from that of a cruciform ship engine plunger, such as a spindle forged product for an engine having a flange, and has a mechanism and a machine in another technical field (for example, automobile). It is to be noted that forgings used in the above are not subject to application.

Hereinafter, with reference to the accompanying drawings will be described in detail the advantages, features and preferred embodiments of the present invention.

SKD7 or DH32 is an alloy named as the steel standard is known to have the components shown in Table 1, the remaining components are composed of iron (Fe). In more detail, the SKD7 material is named according to JIS steel standard and is not produced in Korea, so it is a standard that KS does not have. DH32 is a material developed and used by DAIDO steel.

Chemical composition (%) C Si Mn P S Cu Ni Cr Mo V SKD7 0.32 ~
0.42 0.8 ~
1.2 0.5
Below 0.03
Below 0.03
Below 4.5 ~
5.5 1.0 ~
1.5 0.8 ~
1.2 DH32 0.5 0.13 0.75 0.07 0.02 0.5 0.95 2.4 2.9 0.97

Figure 2 is a forged shape of the ship engine fuel pump plunger which is the final product according to the hot forging manufacturing method of the present invention, Figure 3 is an embodiment according to the invention forging the plunger using a special hot-hole oral cavity (DH32, SKD7) 4 is a schematic view of the process of FIG. 3.

As can be seen in Figure 2, the marine engine fuel pump plunger forging (2) to be manufactured by the present invention is a pair of plunger wings protruding in a symmetrical structure at one end of the plunger shaft portion 22, the shaft portion It consists of 21 and the plunger head 23, and forms the cross shape (†) shaft as a whole.

Each process of the method for manufacturing a ship engine fuel pump plunger using the DH32 or SKD7 special hot working mouth according to the present invention will be described.

After cutting (4) the DH32 or SKD7 raw material to a certain length (31 process in FIG. 3 and reference numeral 4 in FIG. 4), the preform 5 having a specific shape to smoothly form the plunger and reduce the forging load. It is molded into a shape (step 32 in FIG. 3 and reference numeral 5 in FIG. 4). The preform has a great influence on the liveness and forging load of the forging depending on how the shape is designed, which is directly related to the quality of the product and the life of the mold. In view of the foregoing, the preform according to the preferred embodiment of the present invention, which can greatly reduce the forging load and ensure good fatness, has a first cylindrical portion formed in a cylindrical shape having a first diameter. And a second cylindrical portion formed in a cylindrical shape having a second diameter smaller than the first diameter, and an inclined portion formed with a predetermined gradient between the first cylindrical portion and the second cylindrical portion, and having a round bar shape. The first cylindrical portion and the second cylindrical portion having another annular shape form a structure connected by the inclined portion.

When the molding of the preform 5 having the above-described shape and structure is completed through the process of generating a preform of the present invention, a blocker process of forming a preform forging 61 having a predetermined shape so that the final forging may be well formed. This is done (step 33 in FIG. 3 and reference numeral 61 in FIG. 4). The preformed forged product 61 formed through the blocker process has a shape close to the final forged product.

The blocker process of the present invention molds in a direction perpendicular to the longitudinal axis of the preform 5 and forms the preform forging 61 in a hot open forging manner, which is a forged material (ie, a preform) by a blocker mold. ) This is to lower the load applied per unit area of mold during mold casting. That is, the forging load and the stress concentration reducing effect by the hot open forging method together with the forging load and the stress concentration reducing effect realized by the shape characteristics of the preform 5 can be taken together.

When the molding of the preformed forged product is completed through the blocker process, the finisher is molded to satisfy the dimensions of the final forged product (step 34 in FIG. 3). The finisher process is shaped in a vertical direction perpendicular to the longitudinal axis of the preformed forged product 61 in the same manner as the blocker process, and is formed by hot open forging.

When the finisher process is completed, the final shape of the ship engine fuel pump plunger is obtained by performing a trimming process of removing the flash (burr) from the forging product (35 process in FIG. 3 and reference numeral 62 in FIG. 4).

For reference, briefly explaining hot open forging and hot closed forging, the closed forging is a punch inserted into the die in which the forged material is accommodated therein and pressurizes the forged material. Refers to a molding method in which a shape of a desired forged product is obtained by pushing into an internal empty space of a die. Therefore, in closed forging, when the punch is inserted into the die, the area inside the die in which the forged material is accommodated is formed by the punch and the forging process is performed. According to the closed forging, no flash is generated on the outer surface of the forging. Instead of having a shape of the product, the feature of the closed forging that does not generate a flash can be said to be a difference compared to open forging.

Open forging is a method of obtaining the desired forged shape by placing the forged material on the upper part of the lower mold rather than the lower mold and combining the upper mold and the lower mold. In other words, the upper mold is inserted into the lower mold like a closed forging to form a closed space, and the upper mold is lowered to the close distance of the lower mold on which the forged material is placed, and then the forging is stamped and then rises again. The forging process proceeds without the occurrence of the forged material being exposed (opened). Therefore, in the case of open forging, unlike a closed forging in which a punch is inserted into the die to push the forged material into the inner empty space of the die and fill the empty space to produce a desired shape. There is a difference in that the over and under mold pushes a certain amount of the forged material into the gap between the upper mold and the lower mold to generate a flash on the outer surface of the forged product.

5 shows the shape of the preform of the present invention in more detail. The preform has a first cylindrical portion 51 having a first diameter having a diameter equal to that of the raw material, and a second diameter obtained by reducing the diameter of the first cylindrical portion 51 through a hammer forging or machining process. It consists of the 2nd cylindrical part 52 and the inclination part 56 between a 2nd cylindrical part and a 1st cylindrical part.

The total length of the axial direction of the preform of the present invention is molded to have a length shorter than the total length of the axial direction of the preformed forging produced by the blocker process step, but is molded into a shape having a length difference of 1 mm or more and 15 mm or less. This is because, if the length of the preform is longer than the preform forging, waste of unnecessary material and forging load increase, and if the preform is formed with a short length of more than 15 mm in length, mold failure occurs.

In addition, the preform of the present invention is molded into a shape having a diameter difference between the first diameter of the first cylindrical portion and the second diameter of the second cylindrical portion in the range of 8 mm or more and 15 mm or less, wherein the length 55 of the second cylindrical part is 2 according to the second diameter of the cylindrical portion 55 is adjusted to 160 ~ 190mm. The angle 53 between the first cylindrical portion 51 and the second cylindrical portion 52 is applied at 10 ° to 30 °, and the rounded portion of the inclined portion 56 is R20 or more, so that no trace remains in the forged product during the molding process. Do not

If the angle of the inclined portion 56 is less than 10 °, the inclined portion 56 becomes too long, and if the angle of the inclined portion is formed to be greater than 30 °, the first cylindrical portion 51 of the first cylindrical portion 51 is formed when the product is molded in the blocker process. As the flesh (material) is pushed toward the second cylindrical portion 52, marks or folding may occur at a portion where the second cylindrical portion 52 and the inclined portion 56 are connected.

The second diameter of the second cylindrical portion 52 is said to apply φ8 to 15mm smaller than the first diameter of the first cylindrical portion, which means that when the first diameter of the first cylindrical portion is φ60, the second diameter of the second cylindrical portion is φ45 It can be formed at ~ φ52. Since the diameter of the plunger shaft portion 22 is φ44, the second diameter of the second cylindrical portion of the preform must be larger than that in the final production state of the ship engine fuel pump flanger of FIG. 2, and in order to reduce forging load and improve moldability. A preform having a second diameter of φ52 or less is provided, because when larger than φ52, the forging load becomes large, and the purpose thereof cancels out the meaning. Lastly, if the round of the inclined portion 56 is smaller than R20, the flesh (material) of the first cylindrical portion 51 may be pushed out toward the second cylindrical portion 52, whereby marks and folding may occur.

The shape of the preform is designed in a shape that can improve the formability of the forged product and reduce the forging load. Figure 6 is an embodiment according to the present invention, a three-dimensional simulation prediction result by a computer showing the deformation shape for the plunger forging process with or without a preform, Figure 7 is an embodiment according to the present invention, the preform It is a graph showing the forging load predicted in the plunger forging process with and without. 6 shows a case in which the raw material 4 cut without using a preform is applied to the initial billet as it is, and is forged, and is filled in the wing shape 21 of the forged product. In order to complete this, bead shape in the blocker process or more material should be added. Therefore, a large amount of flashes 63 and 64 are generated, which requires high loads 71 and 72 in the blocker and finisher processes.

However, when the preform shape of the present invention is applied as shown in the drawing on the right side of FIG. 6, the length of the second cylindrical portion is made longer than the length of the first cylindrical portion, and the overall length is the length of the preformed forging of the blocker process. Similarly (ie, having a difference in length in the range of 1 to 15 mm), the shape of the final product can be obtained by generating a small amount of flashes 65 and 66 to fill the wing shape 21 of the forging. Therefore, the forging loads 73 and 74 in the blocker and finisher processes can also be significantly reduced because the contact area between the mold and the forging is reduced compared with the case where the preform is not applied.

As described above, for the hot forging of the ship engine fuel pump plunger using the special hot oral cavity (DH32, SKD7), it is necessary to set the correct hot forging temperature for the raw materials, and SKD61 (KS STD61), which is generally used for hot oral cavity, is used. The forging temperature range for the material and the like is known as 1000 ° C ~ 1100 ° C, but the control of the hot forging heating temperature for the special hot-hole oral DH32 and SKD7 material has not been performed until now.

In the present invention, a high temperature compression test was performed by applying various temperatures to control the hot forging temperature for the DH32 or SKD7 material. 8 shows the deformation shape and surface state of the compression test piece according to the heating temperature of the material when the compression test piece 81 having a ratio of 1: 1.5 of diameter and height formed of the DH32 or SKD7 material was compressed until the compression ratio was 50%. 9 shows the metal structure according to the test temperature of the test piece cooled in the air after performing the raw material and the compression test, and FIG. 10 shows the compressive load for each test temperature.

When the surface state of the compression test piece of FIG. 8 was observed, no defects could be found on the surface of the test piece compressed at a heating temperature of 900 ° C. (82), 1000 ° C. (83), and 1100 ° C. (84). 85) and specimens compressed at heating temperatures of 1200 ° C. (86) may find surface cracks. In the specimen structure results of FIG. 9, the specimens at 900 ° C. (92), 1000 ° C. (93), and 1100 ° C. (94) exhibited a good homogeneous overall structure. Compressive specimens at temperatures are very coarse in grain size of 20 µm or more, and can identify pores and carbonized layers between particles. As shown in FIG. 10, in the case of the compressive load 101 at 900 ° C. and the compressive load 102 at 1000 ° C., it can be seen that a considerable load must be increased as the displacement increases, while the displacement increases at 1100 ° C. FIG. It can be seen that the increase in the compression load 103 is significantly reduced.

Therefore, in the present invention, by applying the DH32 and SKD7 materials in the hot forging of the plunger of the ship engine fuel pump, by heating the heating temperature of the material to be in the range of 1080 ℃ ~ 1120 ℃, while obtaining a good structure after hot forging, A temperature range that can be forged with a relatively low load is applied. That is, if hot forging is performed at a temperature exceeding 1120 ° C., cracks are generated in the product. If hot forging is performed at a temperature below 1080 ° C., the forging load is rapidly increased, and thus practical application is difficult. That is, forging can be performed in a 1600 ton press at 1080 ° C. to 1120 ° C., but forging is possible in a press of 2500 tons or more at a temperature of 1080 ° C. or lower, and thus there is difficulty in practical application.

Fig. 11 shows the metal structure 111 of the test piece taken from the product hot-forged at such a temperature range and forcedly cooled by air in the air, and the metal structure 112 after QT heat treatment of the hot forged product. The QT heat treatment of the hot forged product was performed in a vacuum heat treatment furnace, and quenching was performed at a temperature of 650 ° C. for 60 minutes, at 850 ° C. for 150 minutes, at 1020 ° C. for 120 minutes, and then cooled. Tempering was heated at 630 ° C. for 180 minutes and then slowly cooled. At this time, the hardness HRC 37 ~ 39 after the heat treatment was maintained, the metal structure 112 after the heat treatment is spread evenly martensite (martensite) structure throughout the product, it was possible to obtain a very good metal structure.

12 is stress analysis data showing the stress distribution and the numerical value applied to the blocker mold when the preform of the present invention is not applied, and FIG. 13 shows the stress distribution and the numerical value applied to the blocker mold when the preform of the present invention is applied. Show stress analysis data.

Marine engine fuel pump plunger manufacturing method using DH32 or SKD7 special hot hole oral cavity according to the present invention minimizes the high forging load inevitably in forming the special hot hole oral cavity by hot forging method and avoids excessive stress concentration concentrated in the mold The preform creation process was inserted so that the preform could have a specific shape.

Referring to FIG. 12, when the round bar material cut into a cylindrical shape is directly applied without applying the preform of the present invention, that is, when the blocker process is performed immediately (that is, following a general hot forging method), a maximum of 1230 MPa is applied to the blocker mold. It can be seen that this is concentrated. In the case of high stresses, special forgings should be used for hot forging. In case of repeating the forging process under high stress, excessive stress beyond yield strength is concentrated in the blocker mold. This can cause breakage of the mold.

However, referring to FIG. 13, a specific shape according to a preferred embodiment of the present invention (ie, a first cylindrical part and a second cylindrical part, and the first cylindrical part and the second cylindrical part have a circular cross section). When the blocker process is performed by applying the molded preform, it can be seen that the maximum stress acting on the blocker mold is 997 MPa, which is 20% less than that of FIG. 12. As described above, the present invention can significantly reduce the forging load and stress concentration acting on the mold even if the cross (†) type ship engine fuel pump plunger made of a special hot-hole oral material in the hot forging method can be greatly reduced in the repeated operation It is a very useful technique that can prevent mold breakage and ensure good moldability and work in a relatively small forging press.

Although specific embodiments of the present invention have been described and illustrated above, it will be apparent that various modifications may be made by those skilled in the art without departing from the technical spirit of the present invention. Such modified embodiments should not be understood individually from the spirit and scope of the present invention, but should fall within the claims appended to the present invention.

1. Plunger of ship engine fuel pump 11. Round bar raw material
12. Plunger Roughing Products
2. Shape of forged plunger 21. Plunger wing
22. Plunger Shaft 23. Plunger Head
31. Raw material cutting step 32. Preform step
33. Blocker forming step 34. Finisher forming step
35. Trimming step
4. Shape of forging raw material 5. Shape of preform
51. First cylindrical part of preform 52. Second cylindrical part of preform
56. Slope of preform 54. Overall length of preform
55. Preform second cylinder length
61. Blocker shape 62. Finisher shape
63. Blocker Flash 64. Finisher Flash
65. Flasher flasher with preform
66. Flash of finisher using preform
71. Blocker process load 72. Finisher process load
73. Blocker process load with preform
74. Finisher process load with preform
81. Raw material test piece 82. 900 ° C. compression test piece
83. 1000 ℃ Compression Test Piece 84. 1100 ℃ Compression Test Piece
85. 1150 ° C. Compression Test Piece 86. 1200 ° C. Compression Test Piece
91. Raw material metal structure 92. 900 ℃ compression test metal structure
93. 1000 ℃ compression test metal structure 94. 1100 ℃ compression test metal structure
95. 1150 ℃ compression test metal structure 96. 1200 ℃ compression test metal structure
101. 900 ℃ compression test load 102. 1000 ℃ compression test load
103. 1100 ℃ Compression Test Load
111. Organization of hot forged products 112. Organization of hot forged products QT

Claims (6)

As a method for manufacturing a cross (†) ship engine fuel pump plunger using a special hot hole orifice DH32 or SKD7,
A cutting step of cutting the DH32 or SKD7 material into a cylindrical shape;
A first cylindrical portion formed in the cut cylindrical DH32 or SKD7 special hot-hole oral cavity in a cylindrical shape having a first diameter; A second cylindrical portion formed in a cylindrical shape having a second diameter smaller than the first diameter; And a preform forming step of forming a preform formed of an inclined portion formed at an angle of 10 ° to 30 ° between the first cylindrical portion and the second cylindrical portion.
A blocker process step of forming a preformed forged product in a hot open forging manner and mold in a direction perpendicular to the axis of the preform;
A finisher process step of forming a mold in a direction perpendicular to an axis of the preformed forging and hot forming the forging;
A trimming process step of removing the flash to produce a marine engine fuel pump plunger,
In the preform forming step, the length of the second cylindrical portion is molded to be longer than the length of the first cylindrical portion, the preform is the first diameter of the first cylindrical portion and the second diameter of the second cylindrical portion is 8mm or more and 15mm. Method for producing a marine engine fuel pump plunger using the DH32 or SKD7 special hot-hole oral cavity characterized in that it is molded into a shape having a diameter difference in the following range.
The method according to claim 1,
The axial total length of the preform is molded to have a length shorter than the axial total length of the preformed forging produced by the blocker process step, but is formed into a shape having a length difference in the range of 1 mm or more and 15 mm or less. Method for producing a marine engine fuel pump plunger using DH32 or SKD7 special hot air hole.
The method according to claim 1,
The preform is a marine engine fuel pump plunger manufacturing method using a DH32 or SKD7 special hot-hole oral cavity, characterized in that formed by a hammer forging process.
The method according to claim 1,
The preform is a marine engine fuel pump plunger manufacturing method using the DH32 or SKD7 special hot-hole oral cavity, characterized in that formed by machining.
The method according to claim 1,
The blocker process step and the finisher process step is a marine engine fuel pump plunger manufacturing method using DH32 or SKD7 special hot-hole oral cavity characterized in that the hot forging at 1080 ℃ ~ 1120 ℃.
The method according to claim 1,
The round of the inclined portion is a marine engine fuel pump plunger manufacturing method using the DH32 or SKD7 special hot-hole oral, characterized in that the molded in R20 or more.

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