CN117230350A - Diesel engine piston material, diesel engine piston, preparation method of diesel engine piston material and forging die - Google Patents

Diesel engine piston material, diesel engine piston, preparation method of diesel engine piston material and forging die Download PDF

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Publication number
CN117230350A
CN117230350A CN202311200648.9A CN202311200648A CN117230350A CN 117230350 A CN117230350 A CN 117230350A CN 202311200648 A CN202311200648 A CN 202311200648A CN 117230350 A CN117230350 A CN 117230350A
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piston
diesel engine
forging
blank
engine piston
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Inventor
廖从来
易绿林
杨志勇
王熹
向南苗
胡忆明
赵刚建
乔佳旭
帅芳
张咏
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Hunan Jiangbin Machinery Group Co Ltd
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Hunan Jiangbin Machinery Group Co Ltd
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Priority to CN202311200648.9A priority Critical patent/CN117230350A/en
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

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  • Pistons, Piston Rings, And Cylinders (AREA)
  • Forging (AREA)

Abstract

The invention relates to the field of diesel engine piston forging, in particular to a diesel engine piston material, a diesel engine piston, a preparation method thereof and a forging die. The diesel engine piston material provided by the invention comprises the following components: si:14.1 to 18.3 weight percent; ni:1.6 to 3.2 weight percent; fe:0.8 to 1.6 weight percent; mg:0.3 to 0.6 weight percent; cr:0.01 to 0.05 weight percent; zn:0.06 to 0.3 weight percent; ti:0.02 to 0.2 weight percent; zr:0.07 to 0.2 weight percent; v:0.1 to 0.18 weight percent; al: the balance. The piston material is applied to piston preparation, and the layering temperature is kept at the forging part in the forging process, so that the deformation and the forming performance of the piston material are improved, the linear expansion coefficient is reduced, the volume stability is improved, the thermal deformation amount is reduced, and the service life of the piston is prolonged.

Description

Diesel engine piston material, diesel engine piston, preparation method of diesel engine piston material and forging die
Technical Field
The invention relates to the field of diesel engine piston forging, in particular to a diesel engine piston material, a diesel engine piston, a preparation method thereof and a forging die.
Background
The shipping cost of the ship is far lower than that of automobiles, trains and planes, the shipping is rapidly developed in the global trade globalization process, the use amount of the ship is greatly increased, and according to statistics, 75% of the global trade is completed through the shipping of the ship. The diesel engine has good economy, high reliability and long service life, and is widely applied to ships.
The piston and piston ring assembly is one of the most severe components of the diesel engine, and has the functions of supporting the piston, transferring combustion heat, controlling lubricating oil distribution and sealing gas in the combustion chamber. Because of the importance of the piston, the accuracy in the design stage and the processing has direct influence on the economy, reliability, maintenance period and service life of the diesel engine.
At present, a large-cylinder-diameter marine diesel engine is developed from low power and low rotation speed to high power and medium and high rotation speed, and the failure conditions such as piston skirt cylinder pulling, abnormal abrasion of pin holes and outer circle surfaces and the like easily occur in the use process of the diesel engine.
The invention discloses a precision forging forming method of an aluminum alloy piston seat of a passenger plane (patent number 202310012597.0). The patent all proposes an aluminum alloy forging process. However, the following problems still remain unsolvable:
1) 4032 aluminum alloy, which is a heat-treatable aluminum alloy in deformed aluminum, is a silicon-aluminum eutectic alloy, and the main component of the alloy is an alloy element such as Al, si, cu, mg, ni, zn, cr, mn, fe, as shown in table 1:
TABLE 1 4032 Main chemical Components (wt%) of aluminum alloy
Si Cu Mg Ni Fe Cr Zn Al
11-13 0.5-1.3 0.8-1.3 0.5-1.5 ≤1.0 ≤0.1 ≤0.25 Allowance of
The 4032 aluminum alloy has excellent comprehensive mechanical properties, casting performance and machining performance, but has relatively high linear expansion coefficient, poor volume stability and the like, so that the application of the piston in a high-power, medium-high-rotation-speed and large-cylinder-diameter marine diesel engine is seriously affected, the phenomenon of piston cylinder pulling is easy to occur, and even the phenomenon of oil leakage and gas leakage is also caused.
2) At present, the domestic forging piston is made of 4032 aluminum alloy, the forging temperature range of the aluminum alloy is narrow, the heat conductivity is good, the surface temperature of a forging piece which is in direct contact with a die in the forging process is reduced too fast, the plasticity of the aluminum alloy is reduced, the deformation resistance is increased, the filling is poor, the deformation temperature range is small, the forming is difficult, the forging piece is difficult to form, the forging piece is easy to crack due to the fact that the larger striking force is needed, in addition, when the temperature difference between a blank and the die is too large, the surface temperature of the blank is reduced rapidly, a thicker coarse grain layer can be formed in the forging process, the coarse grain defect can not be eliminated in the subsequent heat treatment, and the performance of the forging piece is reduced. According to the existing piston use conditions and development trend, the forging die and the forging process are further optimized, adjusted and controlled so as to obtain excellent tissues and performances.
3) The diameter of the piston skirt part for the high-power, medium-high-rotation-speed and large-cylinder-diameter ship is generally larger, the diameter is generally larger than or equal to 170mm, the pin seat part of the piston skirt part for the large-cylinder-diameter ship is thick, the skirt part is relatively thinner, and the section change is large and is not easy to be fully formed when seen along the central line direction; the circular arc at the bottom end of the pin seat is smaller (R is less than or equal to 3 mm), the filling is not facilitated, and the skirt part of the piston port has stress concentration. Under the condition that the existing forging process and method are unchanged, the fluidity of the aluminum alloy in the deformation process is poor, the metal is difficult to fill the groove in the die forging forming process, folding defects are easy to form, the adhesiveness of the aluminum alloy is large, when the aluminum alloy is greatly deformed in the forging process, a workpiece is easy to adhere to a die, the demolding is difficult, the forge piece is easy to peel after demolding, even warping is generated, and meanwhile, the abrasion of the die is also increased.
4) The draft angle of the inner wall of the piston pin seat is smaller, the metal flow is not facilitated, the contact area of the die and the metal is continuously increased along with the downward, upward and circumferential flow of the metal, the friction resistance is also continuously increased, the flow resistance of the metal is increased, therefore, each step is in an ascending trend, the stress of the male die reaches the maximum value when the piston is completely formed, meanwhile, the connection degree of the curved surfaces of the bottom of the piston pin seat and the inner bottom surface of the piston is not smooth enough, the metal flow is hindered, the circular arc lines of the inner bottom surface of the piston are poor, and tiny cracks are generated.
Disclosure of Invention
In view of the above, the technical problem to be solved by the invention is to provide a diesel engine piston material, a diesel engine piston, a preparation method thereof and a forging die.
The invention provides a diesel engine piston material, which comprises the following components:
si:14.1 to 18.3 weight percent; ni:1.6 to 3.2 weight percent; fe:0.8 to 1.6 weight percent; mg:0.3 to 0.6 weight percent; cr:0.01 to 0.05 weight percent; zn:0.06 to 0.3 weight percent; ti:0.02 to 0.2 weight percent; zr:0.07 to 0.2 weight percent; v:0.1 to 0.18 weight percent; al: the balance.
In one embodiment of the invention, the diesel piston material comprises the following components:
si:14.3wt%; ni:2.8wt%; fe:1.4wt%; mg:0.3wt%; cr:0.02wt%; zn:0.09wt%; ti:0.11wt%; zr:0.07wt%; v:0.13wt%; al: the balance.
In another embodiment of the invention, the diesel piston material comprises the following components:
si:16.2wt%; ni:2.4wt%; fe:1.2wt%; mg:0.45wt%; cr:0.03wt%; zn:0.11wt%; ti:0.15wt%; zr:0.11wt%; v:0.1wt%; al: the balance;
in another embodiment of the invention, the diesel piston material comprises the following components:
si:17.9wt%; ni:1.6wt%; fe:0.8wt%; mg:0.6wt%; cr:0.04wt%; zn:0.3wt%; ti:0.2wt%; zr:0.18wt%; v:0.15wt%; al: the balance.
In the piston material of the diesel engine, fe and Ni element mainly adopt alloy phase Al 9 FeNi exists in a form, so that the heat resistance of the alloy is mainly improved, the linear expansion coefficient of the alloy is reduced, and the volume stability of the piston is improved. As shown in FIG. 1, FIG. 1 is an alloy electron microscope structure diagram of a diesel engine piston material according to the present invention. In the as-cast sample, the elements Fe and Ni are in alloy phase Al 9 When FeNi exists in the form of Al 9 The FeNi phase is flexibly skeletonized and dispersed in the alloy matrix. In certain embodiments of the invention, the mass ratio of Ni to Fe is (1.0-2.0): 1.
the diesel engine piston material provided by the invention is a novel hypereutectic aluminum-silicon alloy material, and can be applied to the preparation of diesel engine pistons, so that the linear expansion coefficient can be reduced, the volume stability of the pistons is improved, and the thermal deformation of the pistons in operation is reduced.
The invention also provides a preparation method of the diesel engine piston, which comprises the following steps:
and forging and forming the diesel engine piston blank in a forging die, and performing heat treatment to obtain the diesel engine piston.
The diesel engine piston blank is composed of the diesel engine piston material. In some embodiments of the invention, the upper part of the diesel engine piston blank is an elliptic cylinder, the lower part of the diesel engine piston blank is a positioning round table, the lower surface of the positioning round table is consistent with the positioning conical surface of the lower insert of the forging die, the rod blank made of the diesel engine piston material is obtained after upsetting and molding, and the roughness of the rod blank is below 12.5 mu m.
In order to uniformly heat the interior of a material, eliminate stress generated by heating and simultaneously uniformly make the material structure, the rod blank is required to be heated to 480-520 ℃ before upsetting, preferably to 480-500 ℃ and is kept for more than 5 hours. In some embodiments of the invention, the heated and insulated rod blank is subjected to upsetting forming in an upsetting die by adopting a two-hammer forming method, wherein first hammer upsetting is performed at a speed of 383-426 m/min, and second hammer upsetting is performed at a speed of 502-534 m/min, so that the diesel engine piston blank is obtained. The upsetting ratio of the upsetting forming is 1.2-2.2, and the upsetting deformation is 0.1-0.2. The temperature of the diesel engine piston blank obtained after upsetting and shaping is 460-500 ℃. The upsetting die is provided with the positioning cylindrical boss for upsetting the rod blank into the shape of the diesel engine piston blank, is favorable for positioning in the next forming process, ensures that the die punch and the blank maintain good coaxiality, and improves the coaxiality of the piston inner cavity and the skirt.
The invention firstly carries out forging forming on the diesel engine piston blank in a forging die. The temperature of the diesel engine piston blank before forging forming is 460-500 ℃. In some embodiments of the present invention, the diesel piston blank obtained after the upsetting is built into a forging die at 20 seconds, a first hammer forging is performed at a speed of 594-621 m/min, a second hammer forging is performed at a speed of 784-819 m/min, and the diesel piston blank is at a speed of 0.28-0.69 seconds -1 Is formed by forging at a strain rate of (2).
The forging forming temperature is 182-253 ℃; specifically, the diesel engine piston blank is forged and molded in a forging die with the temperature of 182-253 ℃. The forging forming temperature of the thicker side of the piston skirt part of the diesel engine piston blank is 10-20 ℃ higher than that of the thinner side; specifically, the temperature of the die part corresponding to the thicker side of the piston skirt of the diesel engine piston blank in the forging die is 10-20 ℃ higher than the temperature of the die part corresponding to the thinner side of the piston skirt of the diesel engine piston blank. The forging forming temperature of the piston skirt part of the diesel engine piston blank is 40-60 ℃ higher than that of the piston top; specifically, the temperature of the die part of the forging die corresponding to the piston skirt of the diesel engine piston blank is 40-60 ℃ higher than the temperature of the die part corresponding to the piston top of the diesel engine piston blank.
In certain embodiments of the present invention, prior to forging, the present invention preheats the forging die to 182-253 ℃, and causes the temperature of the thicker side of the piston skirt corresponding to the diesel piston blank in the die to be 10-20 ℃ higher than the temperature of the thinner side of the piston skirt corresponding to the diesel piston blank in the die, and causes the forging temperature of the piston skirt corresponding to the diesel piston blank in the die to be 40-60 ℃ higher than the forging temperature of the piston top. The invention keeps the temperature of other parts of the diesel engine piston blank basically constant in the whole forging forming process, the forging forming temperature difference between the thick and thin sides of the arranged piston skirt and the forging forming temperature difference between the piston skirt and the piston top improve the fluidity of the piston skirt and the piston top, and promote the filling, thereby reducing the coarse crystal defect and improving the mechanical property of the finally obtained diesel engine piston.
The diesel engine piston blank is subjected to forging forming in a forging die and then is subjected to heat treatment, so that the diesel engine piston is obtained. Specifically, the invention carries out solution treatment and artificial aging on the blank after forging and forming to obtain the diesel engine piston. The solid solution treatment of the invention specifically comprises the following steps: heating to 475-485 deg.c for 1.5-3 hr and maintaining for 0.5-1 hr; heating to 505-525 ℃, heating for 0.5-1 h, and preserving heat for 3-4 h; water cooling is carried out for 5-15 min within 25 s. The artificial aging of the invention is specifically as follows: heating to 175-185 deg.c for 1-3 hr and maintaining for 7-8 hr.
The invention provides a diesel engine piston which is prepared by the preparation method. The diesel engine piston provided by the invention comprises a piston skirt and a piston top. The piston skirt of the diesel engine piston provided by the invention has an asymmetric structure on two sides taking the central axis of the piston as a reference, one side of a pin seat of the piston skirt is thicker, and the other side of the pin seat of the piston skirt is thinner. The piston top of the diesel engine piston provided by the invention is a trumpet-shaped piston top; the area ratio of the top of the trumpet-shaped piston to the skirt of the diesel engine piston is (0.35-0.55): 1.
the invention also provides a forging die applied to the preparation method of the diesel engine piston, which comprises a die body and a heating coil arranged in the die body; the heating coil is used for heating the thick and thin two sides of the piston skirt of the diesel engine piston blank and the piston top of the diesel engine piston blank. Specifically, the forging die of the present invention comprises: the heating coil is characterized by comprising a punch, a push rod, an upper insert, a lower insert and heating coils which are arranged in the lower insert and are uniformly distributed in the circumference. As shown in fig. 2, fig. 2 is a front cross-sectional view of the forging die of the present invention, wherein the forging die in fig. 2 comprises a top rod, an upper insert 1, a lower insert 2, a lower cushion 3, a top rod 4, a punch 5, heating coils 201 arranged in the lower insert and uniformly distributed circumferentially, and a heat insulation plate 202 arranged on the heating coils 201, and the lower cushion 3 is arranged on the top rod 4; also included in fig. 2 is a diesel piston blank 6 placed in the forging die, the diesel piston blank 6 having a piston skirt 601 and a piston crown 602. It should be noted that the diesel piston blank 6 shown in fig. 2 is formed and forged by the ram 5 and has a structure of the final piston part, a top cross section of which is shown in fig. 3, fig. 3 is a top cross section of the diesel piston blank 6 according to the present invention, and fig. 3 shows piston skirt 601 and piston tops 602, 603 and 604 of which are piston pin bosses on two sides of the symmetrical thickness of the piston skirt 601, and it is seen that the pin bosses of the piston skirt of the diesel piston blank 6 according to the present invention have a thicker thickness on one side and a thinner thickness on the other side, so that the piston skirt of the final piston has an asymmetric structure on two sides with respect to the central axis of the piston.
The lower insert of the forging die is provided with a cavity for forming the diesel engine piston, and the upper part of the lower insert corresponds to the piston skirt and the piston top of a diesel engine piston blank. The heating coil of the forging die is used for heating the thick and thin two sides of the piston skirt of the diesel engine piston blank and the piston top of the diesel engine piston blank; specifically, the heating coil heats the upper part of the lower insert, the upper die of the lower insert is preheated to 182-253 ℃, the temperature of the upper part of the lower insert corresponding to the thick edge of the pin seat of the piston skirt is 10-20 ℃ higher than the temperature of the thin edge, the temperature of the other part of the blank is kept basically constant in the whole forging forming process, the temperature of the piston skirt is 40-60 ℃ higher than the temperature of the top of the piston, and the fluidity of the piston skirt is improved.
Further, since the diesel engine piston provided by the invention has an asymmetric structure, the punch of the forging die also has an asymmetric structure, and stress concentration exists on the skirt portion of the piston port, as shown in fig. 4, and fig. 4 is a schematic structural diagram of the piston punch. Therefore, the upper part of the lower insert is provided with a large arc with the arc radius R more than or equal to 10mm corresponding to the uppermost end of the piston skirt of the diesel engine piston blank, and simultaneously, left flash grooves and right flash grooves with different depths are arranged according to the thickness of a piston pin seat (the flash grooves are in asymmetric design), wherein the left flash grooves are arranged on one side of the thicker piston skirt, the right flash grooves are arranged on one side of the thinner piston skirt, and the fluidity of the flash of the forged piston skirt is improved. As shown in fig. 5, fig. 5 is a side sectional view of the forging die according to the present invention, and as can be seen from fig. 5, the lower insert 2 of the forging die according to the present invention includes a left flash groove 203 of a piston blank, a right flash groove 204 of the piston blank, and a large arc 205 with an arc radius R being equal to or greater than 10 connected to the left flash groove 203 of the piston blank; other reference numerals are the same as those of fig. 2 and will not be described again.
Further, as shown in fig. 6, fig. 6 is a schematic diagram of a piston blank produced by the forging die of the present invention, where the horn-shaped recess is used to form a horn-shaped piston top of a diesel piston blank, so as to obtain a diesel piston with a horn-shaped piston top, and the area ratio of the horn-shaped piston top to the piston skirt is 0.35-0.55: 1, a step of; the maximum diameter of the trumpet-shaped piston concave is larger than or equal to the maximum diameter of a punch of the forging die; the uppermost part of the horn-shaped piston concave is a positioning conical surface consistent with the positioning cone of the diesel engine piston blank. In addition, the upper part of the lower insert of the forging die is provided with an annular extrusion groove, and the annular extrusion groove is provided with 3 exhaust grooves. As shown in fig. 7, fig. 7 is a detailed cross-sectional view of the lower insert 2 of the forging die and the diesel engine piston blank 6 according to the present invention, wherein the piston top 603 is seen in fig. 7, the area covered by "+" represents the area of the entire horn-shaped piston top 603 of the piston blank 6, and the area covered by the long-dashed line in fig. 7 represents the area of the entire piston skirt of the piston blank 6; 207 in fig. 7 represents an extrusion groove 207;208 represents the upset slug locating conical surface; 209 represent 3 vent holes provided in the lower insert.
In addition, as shown in fig. 8, fig. 8 is a schematic view of the draft angle of the inner wall of the pin boss, and the punch 5 of fig. 8 can see that the draft angle of the pin boss is small. The trumpet-shaped piston top 603 and the 3 exhaust holes improve the flow of alloy metal, so that the forming quality of the piston inner cavity is high, the defects of cracking, rolling and the like are avoided, and the problem of metal flow blockage caused by smaller draft angle of the inner wall of the piston pin seat is solved.
The invention provides a diesel engine piston material, a diesel engine piston, a preparation method thereof and a forging die. The diesel engine piston material provided by the invention comprises the following components: si:14.1 to 18.3 weight percent; ni:1.6 to 3.2 weight percent; fe:0.8 to 1.6 weight percent; mg:0.3 to 0.6 weight percent; cr:0.01 to 0.05 weight percent; zn:0.06 to 0.3 weight percent; ti:0.02 to 0.2 weight percent; zr:0.07 to 0.2 weight percent; v:0.1 to 0.18 weight percent; al: the balance. The diesel engine piston material provided by the invention is applied to the preparation of diesel engine pistons, and the forging part keeps layering temperature in the forging process, so that the deformability and the forming property of the diesel engine piston material are improved, the linear expansion coefficient is reduced, the volume stability of the piston is improved, the thermal deformation amount of the piston in operation is reduced, the uniform, stable and reliable quality of the piston is ensured, and the service life of the high-power, medium-high-speed and large-cylinder-diameter ship piston is prolonged.
Drawings
FIG. 1 is an alloy electron microscope tissue diagram of a diesel engine piston material according to the invention;
FIG. 2 is a front cross-sectional view of a forging die of the present invention;
fig. 3 is a top cross-sectional view of a diesel engine piston blank 6 according to the invention;
FIG. 4 is a schematic view of a piston ram according to the present invention;
FIG. 5 is a side cross-sectional view of a forging die of the present invention;
FIG. 6 is a physical diagram of a piston blank produced by the forging die of the present invention;
FIG. 7 is a detailed cross-sectional view of the lower insert 2 and diesel piston blank 6 of the forging die of the present invention;
FIG. 8 is a schematic drawing of the draft angle of the interior wall of the piston pin boss;
FIG. 9 is a block diagram of an upsetting die used in the present invention;
FIG. 10 is a schematic flow chart of a diesel engine piston blank obtained by upsetting a rod blank according to the present invention;
FIG. 11 is a diagram of the alloy wrought gold phase of the resulting diesel piston of the present invention.
Detailed Description
The invention discloses a diesel engine piston material, a diesel engine piston, a preparation method thereof and a forging die. Those skilled in the art can, with the benefit of this disclosure, suitably modify the process parameters to achieve this. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and are deemed to be included in the present invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that the invention can be practiced and practiced with modification and alteration and combination of the methods and applications herein without departing from the spirit and scope of the invention.
Firstly, preparing a bar blank before forging to obtain the bar blank, upsetting the bar blank by adopting an upsetting die to obtain a diesel engine piston blank, then placing the obtained diesel engine piston blank into a lower insert of a forging die which is fixed in advance, heating the lower insert in advance, and then performing a piston forming and heat treatment process to obtain the diesel engine piston.
The upsetting die used in the present invention is shown in fig. 9, and fig. 9 is a structural diagram of the upsetting die used in the present invention, and it can be seen from fig. 9 that the upsetting die of the present invention comprises an upper upsetting die 7, a lower upsetting die 8, and a positioning cylindrical boss 9 provided on the lower upsetting die 8. The appearance of the rod blank is a cylinder, the rod blank is placed on a positioning cylinder boss 9 of the positioning cylinder boss, and the two-hammer forming is carried out on the rod blank by using an upsetting die 7, so that a diesel engine piston blank is obtained. As shown in fig. 10, fig. 10 is a schematic flow chart of a diesel engine piston blank obtained by upsetting a rod blank according to the present invention.
The forging die adopted by the invention is the same as the forging die, and is not repeated.
The rod blank made of the diesel engine piston material is used for preparing the diesel engine piston, and the specific components are shown in table 2:
TABLE 2 piston Material preparation of stock composition (wt%)
Element(s) Si Ni Fe Mg Cr Zn Ti Zr V Al
Content of 14.1～18.3 1.6～3.2 0.8～1.6 0.3～0.6 0.01～0.05 0.06～0.3 0.02～0.2 0.07～0.2 0.1～0.18 Allowance of
The actual piston material composition of the rod stock used in each example and comparative example is shown in table 3:
table 3 example and comparative example piston materials made into billet composition (wt%)
The invention is further illustrated by the following examples:
example 1
The preparation of the diesel engine piston is carried out according to the following forging forming process steps:
1) Preparation before forging: blanking according to a certain proportion, wherein the bar size is phi 130 multiplied by 242mm, turning the end face of the optical bar blank, and the roughness is less than or equal to 12.5 mu m, so as to obtain a bar blank;
2) Heating the blank: heating the rod blank obtained in the step 1) before forging in a box-type electric furnace, and when the rod blank is heated to 515 ℃ of the product, in order to uniformly heat the interior of the material, eliminating stress generated by heating, simultaneously uniformly organizing the material, and preserving heat for 5.5 hours;
3) Fixing a die: the punch is fixed to the upper insert, and the upper insert is fixed to the electric screw press. Fixing the lower insert in the lower forging die positioning groove;
4) Heating the lower insert: the heating coil heats the upper part of the lower insert, the upper die of the lower insert is preheated to 245 ℃, the temperature of the thicker side of the piston skirt part of the upper die of the insert is kept higher than the temperature of the thinner side by 18 ℃, the temperature of the other part of the blank is kept basically constant in the whole forging forming process, the temperature of the piston skirt part is higher than the temperature of the top of the piston by 55 ℃, and the fluidity of the piston skirt part is improved;
5) Upsetting and forming: when the bar blank in the step 2) is insulated to 515 ℃ after the heat preservation time, placing the bar blank into an upsetting die, upsetting and forming by an electric screw press, and forming by two hammers, wherein the first hammer speed is 400 m/min, and the second hammer speed is 520 m/min; upsetting ratio is 1.6, upsetting deformation is 0.15, and temperature after upsetting is 497 ℃; the upsetting die is provided with a positioning cylindrical boss and is used for solving the problem that the coaxiality of a blank of the existing product is poor, and the upsetting die is identical to the upsetting die and is not repeated. The upsetted blank is the diesel engine piston blank provided by the invention, the shape of the blank is that the upper part is an elliptic cylinder, and the lower part is a positioning cone consistent with the positioning conical surface of the lower insert of the forging die, and the details are the same as the above, and the details are not repeated.
6) And (3) piston forming: placing the upsetted diesel engine piston blank into a positioning conical surface in a lower insert die within the time of less than or equal to 20s, wherein an electric screw press performs forming forging, and forming by two hammers, wherein the first hammer speed is 600 m/min and the second hammer speed is 800 m/min; the forging has a low strain rate of 0.48s -1 And (5) performing lower molding.
7) In the forging process, one blank is hooked from the hearth after one blank is forged, and a plurality of blanks are not allowed to be hooked at one time. And checking the forging piece once after 20 pieces are forged, and timely adjusting the abnormality. Spraying the mixed lubricating liquid of graphite and engine oil to the cavity of the die cavity once every time one piece is forged;
8) Polishing the aluminum piston forging blank, polishing the inner cavity and the periphery of the blank by using a pneumatic grinder, and stacking and cooling in a frame;
the heat treatment process comprises the following steps:
9) Solution treatment: heating to 480 ℃, heating for 2.5h, and preserving heat for 0.7h; heating to 520 ℃, heating for 0.8h, and preserving heat for 3.5h; the time for transferring the material from the furnace to the water is less than or equal to 25s, and the water cooling time is 10min;
10 Artificial aging): heating to 180 ℃, heating for 2h and preserving heat for 7.5h to obtain the diesel engine piston, wherein as shown in FIG. 11, FIG. 11 is an alloy forging metal phase diagram of the finally obtained diesel engine piston.
Example 2
The preparation of the diesel engine piston is carried out according to the following forging forming process steps:
1) Preparation before forging: blanking according to a certain proportion, wherein the bar size is phi 130 multiplied by 232mm, and the roughness of the end face of the polished rod blank is less than or equal to 12.5 mu m;
2) Heating the blank: heating the rod blank obtained in the step 1) before forging in a box-type electric furnace, and when the temperature of the product is 500 ℃, uniformly heating the interior of the material to eliminate stress generated by heating, uniformly organizing the material and preserving heat for 6.0 hours;
3) Fixing a die: the punch is fixed to the upper insert, and the upper insert is fixed to the electric screw press. Fixing the lower insert in the lower forging die positioning groove;
4) Heating the lower insert: the heating coil heats the upper part of the lower insert, the upper die of the lower insert is preheated to 212 ℃, the temperature difference between the thickness of the piston skirt part of the upper die of the insert and the temperature of the two sides is kept to 15 ℃, the temperature of the other part of the blank is kept to be basically constant in the whole forging forming process, the temperature difference between the piston skirt part and the top of the piston is 50 ℃, and the fluidity of the piston skirt part is improved;
5) Upsetting and forming: when the bar blank in the step 2) is insulated to 500 ℃ after the heat preservation time, placing the bar blank into an upsetting die, upsetting and forming by an electric screw press, and forming by two hammers, wherein the first hammer speed is 405 m/min, and the second hammer speed is 514 m/min; upsetting ratio is 1.9, upsetting deformation is 0.18, and temperature after upsetting is 484 ℃; the upsetting die is provided with a positioning cylindrical boss and is used for solving the problem that the coaxiality of a blank of the existing product is poor, and the upsetting die is identical to the upsetting die and is not repeated. The upsetted blank is the diesel engine piston blank provided by the invention, the shape of the blank is that the upper part is an elliptic cylinder, and the lower part is a positioning cone consistent with the positioning conical surface of the lower insert of the forging die, and the details are the same as the above, and the details are not repeated.
6) And (3) piston forming: placing the upsetted diesel engine piston blank into a positioning conical surface in a lower insert die within the time of less than or equal to 20s, wherein an electric screw press performs forming forging, and two hammers are formed, wherein the first hammer speed is 613 m/min, and the second hammer speed is 786 m/min; the strain rate of the forging piece is 0.64s at a lower rate -1 And (5) performing lower molding.
7) In the forging process, one blank is hooked from the hearth after one blank is forged, and a plurality of blanks are not allowed to be hooked at one time. And checking the forging piece once after 20 pieces are forged, and timely adjusting the abnormality. Spraying the mixed lubricating liquid of graphite and engine oil to the cavity of the die cavity once every time one piece is forged;
8) Polishing the aluminum piston forging blank, polishing the inner cavity and the periphery of the blank by using a pneumatic grinder, and stacking and cooling in a frame;
the heat treatment process comprises the following steps:
9) Solution treatment: heating to 485 ℃, heating for 3h, and preserving heat for 1h; heating to 525 ℃, heating for 1h, and preserving heat for 4h; the time for transferring the material from the furnace to the water is less than or equal to 25s, and the water cooling time is 15min;
10 Artificial aging): heating to 185 ℃, heating for 3h, and preserving heat for 8h to obtain the diesel engine piston.
Example 3
The preparation of the diesel engine piston is carried out according to the following forging forming process steps:
1) Preparation before forging: blanking according to a certain proportion, wherein the bar size is phi 130 multiplied by 252mm, and the roughness of the end face of the polished rod blank is less than or equal to 12.5 mu m;
2) Heating the blank: heating the rod blank obtained in the step 1) before forging in a box-type electric furnace, and when the temperature of the rod blank is heated to 520 ℃, in order to uniformly heat the interior of the material, eliminating stress generated by heating, simultaneously uniformly organizing the material, and preserving the heat for 6.5 hours;
3) Fixing a die: the punch is fixed to the upper insert, and the upper insert is fixed to the electric screw press. Fixing the lower insert in the lower forging die positioning groove;
4) Heating the lower insert: the heating coil heats the upper part of the lower insert, the upper die of the lower insert is preheated to 183 ℃, the temperature difference between the thickness of the piston skirt part of the upper die of the insert and the temperature of the two sides is kept at 11 ℃, the temperature of the other part of the blank is kept basically constant in the whole forging forming process, the temperature difference of 42 ℃ exists between the piston skirt part and the top of the piston, and the fluidity of the piston skirt part is improved;
5) Upsetting and forming: when the bar blank in the step 2) is insulated to 520 ℃ after the heat preservation time, placing the bar blank into an upsetting die, upsetting and forming by an electric screw press, and forming by two hammers, wherein the first hammer speed is 425 m/min, and the second hammer speed is 532 m/min; upsetting ratio is 1.3, upsetting deformation is 0.12, and temperature after upsetting is 503 ℃; the upsetting die is provided with a positioning cylindrical boss and is used for solving the problem that the coaxiality of a blank of the existing product is poor, and the upsetting die is identical to the upsetting die and is not repeated. The upsetted blank is the diesel engine piston blank provided by the invention, the shape of the blank is that the upper part is an elliptic cylinder, and the lower part is a positioning cone consistent with the positioning conical surface of the lower insert of the forging die, and the details are the same as the above, and the details are not repeated.
6) And (3) piston forming: placing the upsetted diesel engine piston blank into a positioning conical surface in a lower insert die within the time of less than or equal to 20s, wherein an electric screw press performs forming forging, and forming by two hammers, wherein the first hammer speed is 620 m/min, and the second hammer speed is 819 m/min; the forging has a lower strain rate of 0.29s -1 And (5) performing lower molding.
7) In the forging process, one blank is hooked from the hearth after one blank is forged, and a plurality of blanks are not allowed to be hooked at one time. And checking the forging piece once after 20 pieces are forged, and timely adjusting the abnormality. Spraying the mixed lubricating liquid of graphite and engine oil to the cavity of the die cavity once every time one piece is forged;
8) Polishing the aluminum piston forging blank, polishing the inner cavity and the periphery of the blank by using a pneumatic grinder, and stacking and cooling in a frame;
the heat treatment process comprises the following steps:
9) Solution treatment: heating to 475 ℃, heating for 1.5h, and preserving heat for 0.5h; heating to 505 ℃, heating for 0.5h, and preserving heat for 3h; the time for transferring the material from the furnace to the water is less than or equal to 25s, and the water cooling time is 5min;
10 Artificial aging): heating to 175 ℃, heating for 1h, and maintaining for 7h to obtain the diesel engine piston.
Comparative example 1
The preparation of the diesel engine piston is carried out according to the following forging forming process steps:
1) Preparation before forging: blanking according to a certain proportion, wherein a 4032 alloy is adopted as a forged bar, the bar size is phi 130 multiplied by 232mm, the end face of a polished rod blank is turned, and the roughness is less than or equal to 12.5 mu m;
2) Heating the blank: heating the rod blank obtained in the step 1) before forging in a box-type electric furnace, and when the temperature of the product is 500 ℃, uniformly heating the interior of the material to eliminate stress generated by heating, uniformly organizing the material and preserving heat for 6.0 hours;
3) Fixing a die: the punch is fixed to the upper insert, and the upper insert is fixed to the electric screw press. Fixing the lower insert in the lower forging die positioning groove;
4) Heating the lower insert: the heating coil heats the upper part of the lower insert, the upper die of the lower insert is preheated to 212 ℃, the temperature difference between the thickness of the piston skirt part of the upper die of the insert and the temperature of the two sides is kept to 15 ℃, the temperature of the other part of the blank is kept to be basically constant in the whole forging forming process, the temperature difference between the piston skirt part and the top of the piston is 50 ℃, and the fluidity of the piston skirt part is improved;
5) Upsetting and forming: when the bar blank in the step 2) is insulated to 500 ℃ after the heat preservation time, placing the bar blank into an upsetting die, upsetting and forming by an electric screw press, and forming by two hammers, wherein the first hammer speed is 405 m/min, and the second hammer speed is 514 m/min; upsetting ratio is 1.9, upsetting deformation is 0.18, and temperature after upsetting is 484 ℃; the upsetting die is provided with a positioning cylindrical boss and is used for solving the problem that the coaxiality of a blank of the existing product is poor, and the upsetting die is identical to the upsetting die and is not repeated. The upsetted blank is the diesel engine piston blank provided by the invention, the shape of the blank is that the upper part is an elliptic cylinder, and the lower part is a positioning cone consistent with the positioning conical surface of the lower insert of the forging die, and the details are the same as the above, and the details are not repeated.
6) And (3) piston forming: placing the upsetted diesel engine piston blank into a positioning conical surface in a lower insert die within the time of less than or equal to 20s, wherein an electric screw press performs forming forging, and two hammers are formed, wherein the first hammer speed is 613 m/min, and the second hammer speed is 786 m/min; the strain rate of the forging piece is 0.64s at a lower rate -1 And (5) performing lower molding.
7) In the forging process, one blank is hooked from the hearth after one blank is forged, and a plurality of blanks are not allowed to be hooked at one time. And checking the forging piece once after 20 pieces are forged, and timely adjusting the abnormality. Spraying the mixed lubricating liquid of graphite and engine oil to the cavity of the die cavity once every time one piece is forged;
8) Polishing the aluminum piston forging blank, polishing the inner cavity and the periphery of the blank by using a pneumatic grinder, and stacking and cooling in a frame;
the heat treatment process comprises the following steps:
9) Solution treatment: heating to 485 ℃, heating for 3h, and preserving heat for 1h; heating to 525 ℃, heating for 1h, and preserving heat for 4h; the time for transferring the material from the furnace to the water is less than or equal to 25s, and the water cooling time is 15min;
10 Artificial aging): heating to 185 ℃, heating for 3h, and preserving heat for 8h to obtain the diesel engine piston.
Comparative example 2
The preparation of the diesel engine piston is carried out according to the following forging forming process steps:
1) Preparation before forging: blanking according to a certain proportion, wherein the bar size is phi 130 multiplied by 232mm, and the roughness of the end face of the polished rod blank is less than or equal to 12.5 mu m;
2) Heating the blank: heating the rod blank obtained in the step 1) before forging in a box-type electric furnace, and when the temperature of the product is 500 ℃, uniformly heating the interior of the material to eliminate stress generated by heating, uniformly organizing the material and preserving heat for 6.0 hours;
3) Fixing a die: the punch is fixed to the upper insert, and the upper insert is fixed to the electric screw press. Fixing the lower insert in the lower forging die positioning groove;
4) Upsetting and forming: when the bar blank in the step 2) is insulated to 500 ℃ after the heat preservation time, placing the bar blank into an upsetting die, upsetting and forming by an electric screw press, and forming by two hammers, wherein the first hammer speed is 405 m/min, and the second hammer speed is 514 m/min; upsetting ratio is 1.9, upsetting deformation is 0.18, and temperature after upsetting is 484 ℃; the upsetting die is provided with a positioning cylindrical boss and is used for solving the problem that the coaxiality of a blank of the existing product is poor, and the upsetting die is identical to the upsetting die and is not repeated. The upsetted blank is the diesel engine piston blank provided by the invention, the shape of the blank is that the upper part is an elliptic cylinder, and the lower part is a positioning cone consistent with the positioning conical surface of the lower insert of the forging die, and the details are the same as the above, and the details are not repeated.
5) And (3) piston forming: placing the upsetted diesel engine piston blank into a positioning conical surface in a lower insert die within the time of less than or equal to 20s, wherein an electric screw press performs forming forging, and two hammers are formed, wherein the first hammer speed is 613 m/min, and the second hammer speed is 786 m/min; the strain rate of the forging piece is 0.64s at a lower rate -1 And (5) performing lower molding.
6) In the forging process, one blank is hooked from the hearth after one blank is forged, and a plurality of blanks are not allowed to be hooked at one time. And checking the forging piece once after 20 pieces are forged, and timely adjusting the abnormality. Spraying the mixed lubricating liquid of graphite and engine oil to the cavity of the die cavity once every time one piece is forged;
7) Polishing the aluminum piston forging blank, polishing the inner cavity and the periphery of the blank by using a pneumatic grinder, and stacking and cooling in a frame;
the heat treatment process comprises the following steps:
8) Solution treatment: heating to 485 ℃, heating for 3h, and preserving heat for 1h; heating to 525 ℃, heating for 1h, and preserving heat for 4h; the time for transferring the material from the furnace to the water is less than or equal to 25s, and the water cooling time is 15min;
9) Artificial aging: heating to 185 ℃, heating for 3h, and preserving heat for 8h to obtain the diesel engine piston.
The diesel engine piston prepared above was subjected to a piston performance test and a piston volume stability test, wherein the piston performance test is shown in table 4, and the piston volume stability test is shown in table 5:
table 4 comparison of examples and comparative example performance results
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Table 5 piston volume stability test comparative examples and comparative examples
The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims (10)

1. A diesel engine piston material comprising the following components:
si:14.1 to 18.3 weight percent; ni:1.6 to 3.2 weight percent; fe:0.8 to 1.6 weight percent; mg:0.3 to 0.6 weight percent; cr:0.01 to 0.05 weight percent; zn:0.06 to 0.3 weight percent; ti:0.02 to 0.2 weight percent; zr:0.07 to 0.2 weight percent; v:0.1 to 0.18 weight percent; al: the balance.
2. The piston material according to claim 1, wherein the mass ratio of Ni to Fe is (1.0 to 2.0): 1.
3. the preparation method of the diesel engine piston is characterized by comprising the following steps of:
forging and forming the diesel engine piston blank in a forging die, and performing heat treatment to obtain a diesel engine piston;
the diesel engine piston blank is composed of the piston material of claim 1 or 2.
4. The method according to claim 3, wherein the forging temperature of the thicker side of the piston skirt of the diesel engine piston blank is 10-20 ℃ higher than the forging temperature of the thinner side;
the forging forming temperature of the piston skirt part of the diesel engine piston blank is 40-60 ℃ higher than that of the piston top.
5. The method according to claim 3, wherein the forging forming temperature is 182 to 253 ℃.
6. A method of preparation according to claim 3, wherein the heat treatment comprises solution treatment and artificial ageing;
the solid solution treatment specifically comprises the following steps: heating to 475-485 deg.c for 1.5-3 hr and maintaining for 0.5-1 hr; heating to 505-525 ℃, heating for 0.5-1 h, and preserving heat for 3-4 h; water cooling is carried out for 5-15 min within 25 s;
the artificial aging specifically comprises the following steps: heating to 175-185 deg.c for 1-3 hr and maintaining for 7-8 hr.
7. A method of preparation according to claim 3, comprising the specific steps of:
after heating and preserving heat of a rod blank made of a diesel engine piston material, upsetting in an upsetting die by adopting a two-hammer forming method, first upsetting by a first hammer at a speed of 383-426 m/min and second upsetting by a second hammer at a speed of 502-534 m/min to obtain a diesel engine piston blank; the upsetting ratio of the upsetting forming is 1.2-2.2, and the upsetting deformation is 0.1-0.2;
placing the obtained diesel engine piston blank in a forging die for 20s, performing first hammer forging at 594-621 m/min, and performing second hammer forging at 784-819 m/min, wherein the diesel engine piston blank is placed in a forging die for 0.28-0.69 s -1 Forging and forming at the strain rate, and then performing heat treatment to obtain the diesel engine piston.
8. A diesel engine piston, characterized in that it is produced by the production method according to any one of claims 3 to 7.
9. The diesel engine piston as set forth in claim 8 wherein the piston crown is a trumpet-shaped piston crown;
the area ratio of the top of the trumpet-shaped piston to the skirt of the diesel engine piston is 0.35-0.55: 1.
10. a forging die applied to the manufacturing method of a diesel engine piston according to any one of claims 3 to 7, characterized by comprising a die body and a heating coil provided in the die body;
the heating coil is used for heating the thick and thin two sides of the piston skirt of the diesel engine piston blank and the piston top of the diesel engine piston blank.
CN202311200648.9A 2023-09-18 2023-09-18 Diesel engine piston material, diesel engine piston, preparation method of diesel engine piston material and forging die Pending CN117230350A (en)

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CN202311200648.9A CN117230350A (en) 2023-09-18 2023-09-18 Diesel engine piston material, diesel engine piston, preparation method of diesel engine piston material and forging die

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Application Number Priority Date Filing Date Title
CN202311200648.9A CN117230350A (en) 2023-09-18 2023-09-18 Diesel engine piston material, diesel engine piston, preparation method of diesel engine piston material and forging die

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CN117230350A true CN117230350A (en) 2023-12-15

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