CN108087141B - Steel piston and manufacturing method thereof - Google Patents
Steel piston and manufacturing method thereof Download PDFInfo
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- CN108087141B CN108087141B CN201711334094.6A CN201711334094A CN108087141B CN 108087141 B CN108087141 B CN 108087141B CN 201711334094 A CN201711334094 A CN 201711334094A CN 108087141 B CN108087141 B CN 108087141B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F3/26—Pistons having combustion chamber in piston head
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
- B23P15/10—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass pistons
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F3/16—Pistons having cooling means
- F02F3/20—Pistons having cooling means the means being a fluid flowing through or along piston
- F02F3/22—Pistons having cooling means the means being a fluid flowing through or along piston the fluid being liquid
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F2003/0007—Monolithic pistons; One piece constructions; Casting of pistons
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F2200/00—Manufacturing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F2200/00—Manufacturing
- F02F2200/04—Forging of engine parts
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- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Pistons, Piston Rings, And Cylinders (AREA)
Abstract
The invention discloses a steel piston.A combustion chamber bottom structure integrated with a piston cylinder is arranged in a piston body, the central part of the bottom of a combustion chamber is protruded towards the direction of the combustion chamber, a combustion chamber cover plate is designed into an annular structure, the combustion chamber cover plate and the piston body adopt an assembly connection mode that an inner ring and an outer ring are in threaded connection to form an annular cooling oil cavity, an oil inlet and outlet hole is arranged at the bottom of the cooling oil cavity, and sealing welding seams are arranged on the outer sides of the matching parts of the combustion chamber cover plate and the piston body to form an integrated steel piston with an inner cooling oil cavity. The steel piston that this scheme provided's simple structure, easily processing, low in manufacturing cost, the shaping of cooling oil pocket is simple, and combustion chamber apron atress is little, and inside and outside double thread connected mode is enough to guarantee that combustion chamber apron can not drop unusually in piston working process. The steel piston of the scheme can meet the requirements of high power, high strength and low emission of the engine. The invention also discloses a manufacturing method of the steel piston.
Description
Technical Field
The invention relates to the technical field of piston design and processing, in particular to a steel piston and a manufacturing method thereof.
Background
The development trend of the engine requires miniaturization, the power is required to be continuously improved, the explosion pressure exceeds 20MPa, the piston bears larger load, and designers of the piston continuously design and improve the material and the structure of the piston to improve the performance, the high-temperature strength and the service life of the piston in order to adapt to the development of the engine. Although the traditional aluminum alloy piston has the advantage of light weight, the aluminum alloy material can only stably work at 350 ℃, the maximum limit working temperature is 400 ℃, the requirements of high power, high strength and low emission of an engine can not be met gradually, the maximum limit working temperature of the steel material piston is 520 ℃, the steel material can meet the requirements of a high-strength piston due to the high strength and high thermodynamic performance of the steel material, and the steel piston is a brand new design scheme behind the aluminum alloy piston. Piston designers have designed steel crown aluminum skirt bolted connection pistons and steel crown aluminum skirt pendulum body type hinged pistons respectively, but two kinds of piston structures all need steel crown and aluminum skirt separately to make, and piston skirt wall thickness difference is difficult to guarantee, and the casting rejection rate is high, and pendulum body type piston is difficult to form closed oil pocket, and piston cooling effect is poor.
Chinese patent CN100453253C discloses a method for manufacturing a one-piece piston for an engine from a piston blank, which has a closed cooling tube and a groove between the piston ring area and the box-shaped piston body in the piston ring area. The method comprises the following steps: the piston blank is produced by forging and the annular groove is produced by machining so that the upper end of the piston skirt remains connected to the radially inner region below the piston crown. The axial height of the groove is at least equal to the axial height of the cooling tube. The open-bottomed cooling tube is machined by machining and in-wheel boring, and the outer contour of the piston is finished. The open-bottomed cooling tube is closed with a two-part ring cover. The technical scheme has the following disadvantages: firstly, the machining difficulty is high, especially limited by the space of the annular groove, the machining of the cooling pipe can be completed only by adding a plurality of high-strength complex machines and cutters, the machining is complex, and the cost is high; secondly, the assembly of the two ring covers of the cooling tube closing the opening is rather difficult.
Chinese patent CN1944994A discloses a welded forged steel monobloc piston and a manufacturing method thereof. The manufacturing method comprises the following steps: respectively forging a head part blank and a skirt part blank; respectively carrying out heat treatment on the head part blank and the skirt part blank; carry out rough machining to head and skirt portion blank respectively, the welding face in the two adjacent annular grooves of head is higher than the welding face of combustion chamber below: friction welding the head and skirt together; respectively processing an annular groove, a combustion chamber, an annular groove, a pin hole, an excircle and an oil inlet and outlet hole of the piston; and (3) carrying out phosphorization or graphite treatment on the surface of the piston. Because the head part and the skirt part of the piston are welded together after being forged respectively, the manufacturability is good compared with the integrally forged piston, because a closed cooling oil cavity is formed by welding, the integral structure rigidity of the piston is increased, particularly, the deformation of the annular groove part under a thermal state is smaller, an annular groove is processed above the skirt part of the piston, the weight of the piston body is reduced, and the oil return of engine oil at the annular groove part, the adjustment of a cylinder matching gap and the reduction of the oil consumption of the engine oil are facilitated. The technical scheme has the following disadvantages: the piston head and the skirt part are welded by a friction welding method, so that craters on the inner surface and the outer surface are easily formed, the craters hidden in a cooling oil cavity are difficult to remove, when an engine runs at a high speed and a high temperature, the craters have a risk of falling, and the craters enter engine cooling systems and other parts along with cooling oil after falling, so that quality accidents such as cylinder scuffing of the engine are easily caused.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a novel steel piston and a manufacturing method thereof, so that the structure and the manufacturing process of the steel piston are simplified, the working reliability and the working safety of the piston are improved, and the requirements of high power, high strength and low emission of an engine can be met.
In order to achieve the purpose, the invention provides the following technical scheme:
a steel piston comprises a piston body and a combustion chamber cover plate, wherein the piston body comprises a piston cylinder, a combustion chamber bottom coaxially connected inside the piston cylinder and a pin shaft connecting part connected below the combustion chamber bottom, the central part of the combustion chamber bottom protrudes towards the combustion chamber direction, a first external thread is arranged on the periphery of the central part, a first internal thread is arranged on the inner ring at the upper end of the piston cylinder, the combustion chamber cover plate is of an annular structure, a second external thread matched with the first internal thread is arranged on the outer ring at the upper end of the combustion chamber cover plate, a second internal thread matched with the first external thread is arranged on the inner ring at the lower end of the combustion chamber cover plate, the combustion chamber bottom and the piston cylinder are in threaded connection to form an annular cooling oil cavity together, and an oil inlet and outlet hole is arranged at the bottom of the cooling, and the outer sides of the matching parts of the first external thread and the second internal thread and the outer sides of the matching parts of the first internal thread and the second external thread are both provided with sealing welding seams.
Preferably, in the above steel piston, an upper mating cylindrical surface is provided between an upper end outer ring of the combustion chamber cover plate and an upper end inner ring of the piston cylinder, and the upper mating cylindrical surface is located above a mating portion of the first internal thread and the second external thread; and a lower matching cylindrical surface is arranged between the inner ring at the lower end of the combustion chamber cover plate and the periphery of the central part, and is positioned above the matching part of the first external thread and the second internal thread.
Preferably, in the above steel piston, the close-fitting weld is formed by argon arc welding, plasma beam welding, electron beam welding or laser beam welding.
Preferably, in the above steel piston, the piston body is a cast or forged member, and the combustion chamber cover plate is a forged member.
Preferably, in the above steel piston, the outer periphery of the piston body is provided with a multi-ring groove.
The steel piston provided by the invention is characterized in that a combustion chamber bottom structure integrated with a piston cylinder is arranged in a piston body, the central part of the bottom of the combustion chamber is protruded towards the direction of the combustion chamber, a combustion chamber cover plate is designed into an annular structure, the combustion chamber cover plate and the piston body are in an assembly connection mode that an inner ring and an outer ring are in threaded connection to form an annular cooling oil cavity, an oil inlet and outlet hole is formed in the bottom of the cooling oil cavity, and a sealing welding seam is arranged on the outer side of a matching part of the combustion chamber cover plate and the piston body to form the integrated steel piston with the inner cooling oil cavity.
The steel piston that this scheme provided's simple structure, easily processing, low in manufacturing cost, the shaping of cooling oil pocket is simple, combustion chamber apron atress is little, the joint strength of inside and outside double thread connected mode is enough to guarantee that combustion chamber apron can not drop unusually in piston working process, the region that the highest and stress of combustion chamber temperature is most concentrated has effectively been dodged to the position of driving fit welding seam moreover, driving fit welding seam stress is little, the risk is low, can improve sealing performance, can play the not hard up effect of preventing threaded connection again, piston safety in utilization has been improved. The steel piston of the scheme can meet the requirements of high power, high strength and low emission of the engine.
The invention also provides a manufacturing method of the steel piston, which comprises the following steps:
processing a piston body blank and a combustion chamber cover plate blank, wherein the piston body blank comprises a piston cylinder, a combustion chamber bottom coaxially connected inside the piston cylinder and a pin shaft connecting part connected below the combustion chamber bottom, the central part of the combustion chamber bottom is protruded towards the combustion chamber direction, the outer ring part of the combustion chamber bottom positioned at the central part forms the bottom of a cooling oil cavity, an oil inlet and outlet hole is processed at the bottom of the cooling oil cavity, and the combustion chamber cover plate is of an annular structure;
heat treatment, respectively carrying out heat treatment on the piston body blank and the combustion chamber cover plate blank;
machining threads, namely machining a first external thread on the periphery of the central part of the bottom of the combustion chamber, machining a first internal thread on the upper end inner ring of the piston cylinder to form a piston body, machining a second external thread which can be matched with the first internal thread on the upper end outer ring of the combustion chamber cover plate blank, machining a second internal thread which can be matched with the first external thread on the lower end inner ring of the combustion chamber cover plate blank to form a combustion chamber cover plate, and ensuring that the internal and external threads of the combustion chamber cover plate can be screwed in and screwed tightly when the combustion chamber cover plate is in threaded connection with the piston body;
the piston is assembled, and the combustion chamber cover plate, the combustion chamber bottom and the piston cylinder are in threaded connection to form an annular cooling oil cavity together;
and processing a sealing welding line, and performing shallow sealing treatment on the outer sides of the matching parts of the first external thread and the second internal thread and the outer sides of the matching parts of the first internal thread and the second external thread.
Preferably, in the above method for manufacturing a steel piston, in the steps of processing the piston body blank and the combustion chamber cover plate blank, the piston body blank is processed by a casting or forging method, and the combustion chamber cover plate blank is processed by a forging method.
Preferably, in the method for manufacturing a steel piston, in the step of machining the close-fitting weld, a welding method of argon arc welding, plasma beam welding, electron beam welding or laser beam welding is adopted.
Preferably, in the above method for manufacturing a steel piston, after the step of machining the close-fitting weld, the method further includes the steps of:
and (3) forming, namely processing a pin hole in the pin shaft connecting part, processing an outer circular part and a plurality of ring grooves in the periphery of the piston cylinder, and processing the upper surface of the central part of the bottom of the combustion chamber and the upper surface of the cover plate of the combustion chamber to form the bottom surface of the combustion chamber.
Preferably, in the above method for manufacturing a steel piston, after the forming step, the method further includes the steps of: and carrying out phosphating treatment on the surface of the steel piston.
The manufacturing method of the steel piston provided by the invention can be used for processing the steel piston product, the manufacturing method is simple in process, the processing tool is easy to clamp, the product precision is easy to guarantee, meanwhile, no crater is left in the welding treatment of the thread matching part, the surface quality of the product is guaranteed, and the service life of the piston is prolonged. In addition, the beneficial effects of the steel piston product processed by the manufacturing method are similar to the derivation process of the beneficial effects brought by the steel piston, and therefore, the description is omitted.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic cross-sectional structural view of a steel piston in an embodiment of the present invention;
FIG. 2 is a schematic view of a combustion chamber cover plate according to an embodiment of the present invention;
fig. 3 is a schematic view of a piston body structure according to an embodiment of the present invention.
In fig. 1 to 3:
1-pin hole, 2-pin shaft connecting part, 3-piston cylinder, 4-oil inlet and outlet hole, 5-cooling oil chamber, 6-ring groove, 7-upper matching cylindrical surface, 8-combustion chamber cover plate, 9-lower matching cylindrical surface, 10-combustion chamber, 11-combustion chamber bottom, 31-first internal thread, 32-first external thread, 81-second external thread and 82-second internal thread.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 to 3, fig. 1 is a schematic cross-sectional structural view of a steel piston according to an embodiment of the present invention; FIG. 2 is a schematic view of a combustion chamber cover plate according to an embodiment of the present invention; fig. 3 is a schematic view of a piston body structure according to an embodiment of the present invention.
In a specific embodiment, the present invention provides a steel piston, comprising a piston body and a combustion chamber cover plate 8, wherein the piston body comprises a piston cylinder 3, a combustion chamber bottom 11 coaxially connected to the inside of the piston cylinder 3, and a pin shaft connecting part 2 connected to the lower side of the combustion chamber bottom 11, the central part of the combustion chamber bottom 11 protrudes toward the combustion chamber 10 and is provided with a first external thread 32 on the periphery of the central part, the inner ring of the upper end of the piston cylinder 3 is provided with a first internal thread 31, the combustion chamber cover plate 8 is of an annular structure, the outer ring of the upper end of the combustion chamber cover plate 8 is provided with a second external thread 81 matched with the first internal thread 31, the inner ring of the lower end of the combustion chamber cover plate 8 is provided with a second internal thread 82 matched with the first external thread 32, the combustion chamber cover plate 8, the combustion chamber bottom 11 and the piston cylinder 3 are in threaded connection to form an annular cooling oil chamber, and the outside of the matching part of the first external thread 32 and the second internal thread 82 and the outside of the matching part of the first internal thread 31 and the second external thread 82 are both provided with a sealing welding seam.
The steel piston that this scheme provided's simple structure, easily processing, low in manufacturing cost, cooling oil cavity 5's shaping is simple, 8 atress of combustion chamber apron, the joint strength of inside and outside double thread connected mode is enough to guarantee that 8 combustion chamber apron can not drop unusually in piston working process, the region that the combustion chamber temperature is the highest and stress is the most concentrated has effectively been dodged to the position of driving fit welding seam moreover, driving fit welding seam stress is little, the risk is low, can improve sealing performance, can play the not hard up effect of preventing threaded connection again, piston safety in utilization has been improved. The steel piston of the scheme can meet the requirements of high power, high strength and low emission of the engine.
Preferably, an upper matching cylindrical surface 7 is arranged between the upper end outer ring of the combustion chamber cover plate 8 and the upper end inner ring of the piston cylinder 3, and the upper matching cylindrical surface 7 is positioned above the matching part of the first internal thread 31 and the second external thread 81; a lower mating cylindrical surface 9 is arranged between the inner ring at the lower end of the combustion chamber cover plate 8 and the outer periphery of the central portion, and the lower mating cylindrical surface 9 is positioned above the mating portion of the first external thread 32 and the second internal thread 82. When the steel piston is assembled, a certain radial clearance is reserved between the threaded connection part between the combustion chamber cover plate 8 and the piston body, and the upper matching cylindrical surface 7 and the lower matching cylindrical surface 9 can reduce threaded connection errors, ensure the matching precision of the upper matching cylindrical surface and the lower matching cylindrical surface and improve the position precision of the cooling oil cavity 5.
It should be noted that the driving fit weld in the present scheme may be formed by various welding methods, such as argon arc welding, plasma beam welding, electron beam welding or laser beam welding, which have shallow welding depth, small welding stress, few defects, low cost, and not only can improve the sealing performance of the fitting portion, but also can prevent the screw thread from loosening, and furthermore, no crater is left in the cooling oil cavity 5, thereby improving the operation safety.
Preferably, the piston body in this scheme is casting or forging, and combustion chamber apron 8 is forging, adopts traditional forming process not only can reduce manufacturing cost, can ensure moreover that the 3 wall thickness of the piston section of thick bamboo of piston body are even, guarantees simultaneously that the piston body inner chamber top, 11 wall thicknesses in combustion chamber bottom are even to guarantee that the heat dissipation is even, avoid heat to concentrate. In addition, because the combustion chamber cover plate 8 is of a simple annular structure and does not have a complex inner cavity structure, a casting forming process is not needed, and circular steel materials can be directly processed in the actual production process.
Preferably, the outer circumference of the piston body is provided with a plurality of ring grooves 6, as shown in fig. 1 and 3. The multi-ring groove 6 is used for installing a plurality of gas rings and oil rings respectively, and the sealing performance between the piston and the piston cavity is guaranteed.
The invention also provides a manufacturing method of the steel piston, which comprises the following steps:
s1: processing a piston body blank and a combustion chamber cover plate blank, wherein the piston body blank comprises a piston cylinder 3, a combustion chamber bottom 11 coaxially connected inside the piston cylinder 3 and a pin shaft connecting part 2 connected below the combustion chamber bottom 11, the central part of the combustion chamber bottom 11 protrudes towards the combustion chamber 10, the outer ring part of the combustion chamber bottom 11 positioned at the central part forms the bottom of a cooling oil cavity 5, an oil inlet and outlet hole 4 is processed at the bottom of the cooling oil cavity 5, and the combustion chamber cover plate 11 is of an annular structure;
s2: heat treatment, namely respectively carrying out heat treatment on the piston body blank and the combustion chamber cover plate blank;
s3: machining threads, namely machining a first external thread 32 on the periphery of the central part of the bottom 11 of the combustion chamber, machining a first internal thread 31 on the inner ring of the upper end of the piston cylinder 3 to form a piston body, machining a second external thread 81 capable of being matched with the first internal thread 31 on the outer ring of the upper end of a blank of a combustion chamber cover plate, and machining a second internal thread 82 capable of being matched with the first external thread 32 on the inner ring of the lower end of the blank of the combustion chamber cover plate to form the combustion chamber cover plate 8, so that the internal and external threads of the combustion chamber cover plate 8 can be screwed at the same time when the combustion chamber cover plate 8 is in threaded connection with;
specifically, in step S3, the piston body blank and the combustion chamber cover blank are respectively subjected to blank processing, a numerical control device with a spindle having a rotation angle control function is adopted, an internal thread turning tool and an external thread turning tool are adopted, and the internal thread and the external thread are processed in a fixed-point processing manner under the condition of one-time positioning and clamping, so that the internal and external threads at the upper and lower ends of the piston body and the combustion chamber cover can be screwed in and screwed at the same time during threaded connection.
S4: assembling a piston, wherein a combustion chamber cover plate 8, a combustion chamber bottom 11 and a piston cylinder 3 are in threaded connection to form an annular cooling oil cavity 5;
s5: and processing a close welding seam, and performing shallow close sealing treatment on the outer sides of the matching parts of the first external thread 32 and the second internal thread 82 and the matching parts of the first internal thread 31 and the second external thread 81.
The manufacturing method of the steel piston provided by the invention can be used for processing the steel piston product, the manufacturing method is simple in process, the processing tool is easy to clamp, the product precision is easy to guarantee, meanwhile, no crater is left in the welding treatment of the thread matching part, the surface quality of the product is guaranteed, and the service life of the piston is prolonged. In addition, the beneficial effects of the steel piston product processed by the manufacturing method are similar to the derivation process of the beneficial effects brought by the steel piston, and therefore, the description is omitted.
Preferably, in the step of processing the piston body blank and the combustion chamber cover plate blank, the piston body blank is processed by a casting or forging method, and the combustion chamber cover plate blank is processed by a forging method. The blank of the cover plate of the combustion chamber can also be directly processed by adopting round steel materials.
Preferably, in step S3, machining a matching cylindrical surface above the thread matching portion, specifically, machining an upper matching cylindrical surface 7 between the upper end outer ring of the combustion chamber cover plate 8 and the upper end inner ring of the piston cylinder 3, where the upper matching cylindrical surface 7 is located above the matching portion of the first internal thread 31 and the second external thread 81; a lower mating cylindrical surface 9 is machined between the lower end inner ring of the combustion chamber cover plate 8 and the outer periphery of the central portion, and the lower mating cylindrical surface 9 is located above the mating portion of the first male thread 32 and the second female thread 82. When the steel piston is assembled in step S4, the threaded connection portion between the combustion chamber cover plate 8 and the piston body has a certain radial clearance, and the upper mating cylindrical surface 7 and the lower mating cylindrical surface 9 can reduce the threaded connection error, ensure the mating accuracy of the two, and improve the position accuracy of the cooling oil chamber 5.
After the piston body and the combustion chamber cover plate 8 are connected and combined together through the inner and outer threads, the process of a sealing weld seam in step S5 is performed, specifically, in step S5, the outer sides of the matching portions of the first outer thread 32 and the second inner thread 82 and the outer sides of the matching portions of the first inner thread 31 and the second outer thread 81 may be subjected to shallow sealing and sealing by using welding methods such as argon arc welding, plasma beam welding, electron beam welding or laser beam welding, and the depth of the sealing weld seam is controlled within 2-3 mm.
It should be noted that the above welding methods are all mature welding methods in the prior art, and the processing process of the close-fit weld seam is specifically described by electron beam welding as follows:
s501: cleaning the welding parts of the upper matching cylindrical surface 7 and the lower matching cylindrical surface 9;
s502: after the combustion chamber cover plate 8 and the piston body are assembled in place, positioning is carried out;
s503: welding by adopting an electron beam welding machine;
s5031: placing the steel piston in an electric heating furnace for preheating, wherein the heating temperature is 230 +/-15 ℃, and preserving the heat for more than two hours;
s5032: placing the steel piston on a special rotary table in an electron beam welding machine for welding, wherein before the welding machine is closed, the surface temperature of the steel piston is 210 +/-15 ℃, and the welding parameters are as follows: the beam voltage is 60KV, the beam current is 50-70 mA, the focusing current is 2.8-4.05A, and the arc-closing angle is 65-85 degrees.
S5033: and opening the welding chamber, and measuring the surface temperature of the steel piston, wherein the temperature is within the range of 250-300 ℃.
Preferably, after the step S5 of processing the close-fit weld, the method further includes the following steps:
s6: and (3) forming, namely, processing a pin hole 1 on the pin shaft connecting part 2, processing an outer circle part and a plurality of ring grooves 6 on the periphery of the piston cylinder 3, and processing the bottom surface of the combustion chamber 10 on the upper surface of the central part of the combustion chamber bottom 11 and the upper surface of the combustion chamber cover plate 8.
Preferably, after the forming process of step S6, the method further includes the following step S7: and carrying out phosphating treatment on the surface of the steel piston. The phosphorization is a protection process for reacting the steel piston with dilute phosphoric acid or phosphate solution to form a phosphate film on the surface of the steel piston, and can improve the corrosion resistance, the wear resistance and the heat resistance of the steel piston. The phosphating process of the steel piston specifically comprises the following steps:
s701: cleaning and deoiling the steel piston, immersing the steel piston into a deoiling solution at the temperature of 60-70 ℃ for 5-15 minutes, and then rinsing the steel piston by flowing water;
s702: immersing the steel piston into a phosphating solution, wherein the temperature of the phosphating solution is 70-75 ℃, the phosphating time is 2-3 minutes, and the steel piston is shaken up, down, left and right as far as possible in the phosphating solution;
s703: the phosphated steel piston is immersed into a flowing water tank for cleaning, residual phosphating solution is not allowed to be left on the surface of a workpiece, and the workpiece with an incomplete phosphating film is directly phosphated;
s704: and (3) putting the steel piston into a washing tank at the temperature of 60-80 ℃ for scalding for 1-2 minutes, and drying the steel piston by using clean compressed air after the steel piston is taken out of the tank.
The steel piston processed according to the manufacturing method has the following advantages:
(1) the wall thickness is uniform, the heat dissipation is uniform, and the heat concentration is avoided;
(2) the area with the highest combustion chamber temperature and the most concentrated stress in the installation process is effectively avoided;
(3) the combustion chamber cover plate bears the explosion pressure in the working process and the running inertia of the self mass, the stress is small, and the connection strength of the inner thread and the outer thread is enough to ensure that the combustion chamber cover plate does not fall off abnormally in the working process of the piston;
(4) the sealing welding seam has shallow welding depth, small stress, few defects and low cost, can improve the sealing performance and also plays a role in preventing the thread from loosening;
(5) the surface of the cooling oil cavity is smooth, and the cooling effect is good;
(6) and the matching cylindrical surface welding lines at the upper end and the lower end can be subjected to shallow layer sealing treatment by one-time clamping, so that the manufacturing cost is reduced.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. The steel piston is characterized by comprising a piston body and a combustion chamber cover plate (8), wherein the piston body comprises a piston cylinder (3), a combustion chamber bottom (11) coaxially connected inside the piston cylinder (3) and a pin shaft connecting part (2) connected below the combustion chamber bottom (11), the central part of the combustion chamber bottom (11) protrudes towards the combustion chamber direction, a first external thread (32) is arranged on the periphery of the central part, a first internal thread (31) is arranged on the inner ring of the upper end of the piston cylinder (3), the combustion chamber cover plate (8) is of an annular structure, a second external thread (81) matched with the first internal thread (31) is arranged on the outer ring of the upper end of the combustion chamber cover plate (8), a second internal thread (82) matched with the first external thread (32) is arranged on the inner ring of the lower end of the combustion chamber cover plate (8), the combustion chamber cover plate (8), the combustion chamber bottom (11) and the piston cylinder (3) are in threaded connection and then form an annular cooling oil cavity (5), an oil inlet and outlet hole (4) is formed in the bottom of the cooling oil cavity (5), and sealing welding seams are arranged on the outer sides of the matching parts of the first external thread (32) and the second internal thread (82) and the outer sides of the matching parts of the first internal thread (31) and the second external thread (81); an upper matching cylindrical surface (7) is arranged between the outer ring of the upper end of the combustion chamber cover plate (8) and the inner ring of the upper end of the piston cylinder (3), and the upper matching cylindrical surface (7) is positioned above the matching part of the first internal thread (31) and the second external thread (81); and a lower matching cylindrical surface (9) is arranged between the inner ring at the lower end of the combustion chamber cover plate (8) and the periphery of the central part, and the lower matching cylindrical surface (9) is positioned above the matching part of the first external thread (32) and the second internal thread (82).
2. The steel piston of claim 1 wherein said close-fitting weld is formed by argon arc welding, plasma beam welding, electron beam welding or laser beam welding.
3. The steel piston according to claim 1, characterized in that the piston body is a casting or forging and the combustion chamber cover plate (8) is a forging.
4. A steel piston according to claim 1, characterized in that the outer periphery of the piston body is provided with a plurality of ring grooves (6).
5. A method of manufacturing a steel piston, comprising the steps of:
processing a piston body blank and a combustion chamber cover plate (8) blank, wherein the piston body blank comprises a piston cylinder (3), a combustion chamber bottom (11) coaxially connected to the inside of the piston cylinder (3) and a pin shaft connecting part (2) connected below the combustion chamber bottom (11), the central part of the combustion chamber bottom (11) is protruded towards the combustion chamber direction, the outer ring part of the combustion chamber bottom (11) positioned at the central part forms the bottom of a cooling oil cavity (5), an oil inlet and outlet hole (4) is processed at the bottom of the cooling oil cavity (5), and the combustion chamber cover plate (8) is of an annular structure;
heat treatment, wherein the piston body blank and the combustion chamber cover plate (8) blank are respectively subjected to heat treatment;
machining threads, machining a first external thread (32) on the periphery of the central part of the bottom (11) of the combustion chamber, machining a first internal thread (31) on the inner ring of the upper end of the piston cylinder (3) to form a piston body, machining a second external thread (81) capable of being matched with the first internal thread (31) on the outer ring of the upper end of a blank of the combustion chamber cover plate (8), machining a second internal thread (82) capable of being matched with the first external thread (32) on the inner ring of the lower end of the blank of the combustion chamber cover plate (8) to form the combustion chamber cover plate (8), ensuring that the internal and external threads of the combustion chamber cover plate (8) can be screwed and screwed simultaneously when in threaded connection with the piston body, machining an upper matching cylindrical surface (7) between the outer ring of the upper end of the combustion chamber cover plate (8) and the inner ring of the upper end of the piston cylinder (3), and positioning the upper matching cylindrical surface (7) between the first internal thread (31) and the second external thread ( A lower matching cylindrical surface (9) is machined between the inner ring at the lower end of the combustion chamber cover plate (8) and the outer periphery of the central part of the combustion chamber bottom (11), and the lower matching cylindrical surface (9) is positioned above the matching part of the first external thread (32) and the second internal thread (82);
the piston is assembled, and the combustion chamber cover plate (8), the combustion chamber bottom (11) and the piston cylinder (3) are in threaded connection and then form the annular cooling oil cavity (5);
and processing a close-fit welding seam, and performing shallow close-fit sealing treatment on the outer sides of the matching parts of the first external thread (32) and the second internal thread (82) and the matching parts of the first internal thread (31) and the second external thread (81).
6. The method for manufacturing a steel piston according to claim 5, wherein in the step of processing a piston body blank and a combustion chamber cover plate (8) blank, the piston body blank is processed by a casting or forging method, and the combustion chamber cover plate (8) blank is processed by a forging method.
7. The method for manufacturing a steel piston as claimed in claim 5, wherein in the step of processing the close-fitting weld, a welding method of argon arc welding, plasma beam welding, electron beam welding or laser beam welding is employed.
8. The method of manufacturing a steel piston according to claim 5, further comprising, after the step of machining a close-fitting weld, the steps of:
and (3) forming, namely processing a pin hole (1) in the pin shaft connecting part (2), processing an outer circle part and a plurality of ring grooves (6) in the periphery of the piston cylinder (3), and processing the upper surface of the central part of the combustion chamber bottom (11) and the upper surface of the combustion chamber cover plate (8) to form the bottom surface of the combustion chamber.
9. The method of manufacturing a steel piston as claimed in claim 8 further comprising, after the forming step, the steps of: and carrying out phosphating treatment on the surface of the steel piston.
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| CN110748434A (en) * | 2019-11-29 | 2020-02-04 | 滨州渤海活塞有限公司 | Steel piston of gasoline engine and manufacturing method thereof |
| CN111550325A (en) * | 2020-05-29 | 2020-08-18 | 滨州渤海活塞有限公司 | High-strength light internal combustion engine piston |
| CN112548506B (en) * | 2020-12-11 | 2022-07-05 | 湖南江滨机器（集团）有限责任公司 | Remanufacturing method of steel piston |
| CN114856852A (en) * | 2022-05-09 | 2022-08-05 | 安徽省恒泰动力科技有限公司 | Large-cylinder-diameter air-cooled diesel engine piston |
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| CN1610601A (en) * | 2001-03-23 | 2005-04-27 | 马勒股份有限公司 | One-piece piston |
| CN101265854A (en) * | 2007-07-20 | 2008-09-17 | 山东滨州渤海活塞股份有限公司 | Laser welding forged steel integral piston with closed inner-cooling oil recess and its fabrication process |
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| DE10340292A1 (en) * | 2003-09-02 | 2005-04-14 | Mahle Gmbh | Piston for an internal combustion engine |
| US8671905B2 (en) * | 2011-07-12 | 2014-03-18 | Mahle International Gmbh | Piston for an internal combustion engine and method for its production |
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| CN1610601A (en) * | 2001-03-23 | 2005-04-27 | 马勒股份有限公司 | One-piece piston |
| CN101265854A (en) * | 2007-07-20 | 2008-09-17 | 山东滨州渤海活塞股份有限公司 | Laser welding forged steel integral piston with closed inner-cooling oil recess and its fabrication process |
| CN204827699U (en) * | 2015-07-31 | 2015-12-02 | 河南省中原活塞股份有限公司 | Composite connection formula piston |
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