CN113898492B - Large-cylinder-diameter forged steel piston and manufacturing method thereof - Google Patents
Large-cylinder-diameter forged steel piston and manufacturing method thereof Download PDFInfo
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- CN113898492B CN113898492B CN202111175351.2A CN202111175351A CN113898492B CN 113898492 B CN113898492 B CN 113898492B CN 202111175351 A CN202111175351 A CN 202111175351A CN 113898492 B CN113898492 B CN 113898492B
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 153
- 239000010959 steel Substances 0.000 title claims abstract description 153
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 16
- 238000003466 welding Methods 0.000 claims abstract description 55
- 239000003921 oil Substances 0.000 claims description 39
- 238000001816 cooling Methods 0.000 claims description 29
- 238000005242 forging Methods 0.000 claims description 26
- 238000010438 heat treatment Methods 0.000 claims description 21
- 238000005461 lubrication Methods 0.000 claims description 21
- 238000005496 tempering Methods 0.000 claims description 20
- 238000010791 quenching Methods 0.000 claims description 15
- 230000000171 quenching effect Effects 0.000 claims description 15
- 239000010687 lubricating oil Substances 0.000 claims description 14
- 238000004140 cleaning Methods 0.000 claims description 8
- 238000001514 detection method Methods 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 6
- 238000003801 milling Methods 0.000 claims description 6
- 230000007547 defect Effects 0.000 claims description 4
- 238000003754 machining Methods 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 238000007664 blowing Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 238000000227 grinding Methods 0.000 claims description 2
- 238000004381 surface treatment Methods 0.000 claims description 2
- 238000007689 inspection Methods 0.000 description 16
- 238000002485 combustion reaction Methods 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 239000006247 magnetic powder Substances 0.000 description 6
- 238000004880 explosion Methods 0.000 description 5
- 238000005553 drilling Methods 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 238000009957 hemming Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000005422 blasting Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 229910001141 Ductile iron Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 210000000707 wrist Anatomy 0.000 description 1
Classifications
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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
- F02F3/0015—Multi-part pistons
- F02F3/003—Multi-part pistons the parts being connected by casting, brazing, welding or clamping
-
- 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
-
- 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
-
- 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
- F02F3/0084—Pistons the pistons being constructed from specific materials
- F02F3/0092—Pistons the pistons being constructed from specific materials the material being steel-plate
-
- 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
-
- 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
- F02F3/0015—Multi-part pistons
- F02F3/003—Multi-part pistons the parts being connected by casting, brazing, welding or clamping
- F02F2003/0061—Multi-part pistons the parts being connected by casting, brazing, welding or clamping by welding
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- Engineering & Computer Science (AREA)
- 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)
- Forging (AREA)
Abstract
The invention discloses a large-cylinder-diameter forged steel piston and a manufacturing method thereof. The invention adopts the connection of the forged steel piston crown and the forged steel piston skirt through inertia friction welding, and the connection mode can meet the application requirements of the high-strength diesel engine; the characteristic parts of the traditional forged steel piston skirt, which are connected by counter bores and bolts, are reduced, and the size and weight of the piston are further reduced.
Description
Technical Field
The invention belongs to the technical field of pistons, and particularly relates to a large-cylinder-diameter forged steel piston and a manufacturing method thereof.
Background
Against the increasingly serious global environmental pollution, the world adopts powerful measures, strict emission regulation standard is implemented, and emission becomes a threshold for the permitted sales of diesel engines. Meanwhile, for a high-power diesel engine, the fuel consumption is the maximum application cost, the requirement of a user on reducing the operation cost is met, the fuel consumption of the diesel engine is reduced, the economy is improved, and the method is a permanent target for the development of the diesel engine. In order to further reduce emission and oil consumption, the highest combustion pressure of the diesel engine is also greatly increased, and the highest combustion pressure reaches 25MPa. In order to improve combustion performance, the piston stroke tends to increase, resulting in an increase in the average piston speed. The increase in average effective pressure and average piston velocity means that the piston specific power also assumes an ever-increasing situation. Thus, modern diesel pistons are first required to have sufficient strength, rigidity and reliability to withstand increasingly higher mechanical and thermal loads; these requirements require that the piston can bear higher mechanical load and thermal load on the premise of maintaining proper size and weight and ensuring reliability, and new requirements are put on the materials and the structure of the piston.
According to the domestic statistics of the existing piston structure and working conditions thereof, the highest explosion pressure range of the diesel engine corresponding to different piston structure forms is as follows: integral aluminum piston: 17-19 MPa; integral aluminum piston: 17-19 MPa; steel top aluminum skirt combined piston: 17-19 MPa; integral ductile iron piston: less than or equal to 20MPa; steel top iron skirt combined piston: less than or equal to 25Mpa; the existing piston has the technical problems of low strength, large size, heavy weight and the like; there is therefore a need for a new piston to solve this technical problem.
Disclosure of Invention
The invention aims to: the invention aims to provide a large-cylinder-diameter forged steel piston capable of bearing high explosion pressure and reducing the size and weight of the piston and a manufacturing method thereof, aiming at the defects of low strength, large size and weight and the like of the piston in the prior art.
The technical scheme for realizing the invention is as follows:
the invention discloses a large-cylinder-diameter forged steel piston, which comprises a forged steel piston top, a forged steel piston skirt and a piston pin hole, wherein the forged steel piston top is connected with the forged steel piston skirt through inertia friction welding, the piston pin hole is provided with a first lubricating oil groove structure and a second lubricating oil groove structure, and the length setting directions of the first lubricating oil groove structure and the second lubricating oil groove structure are in vertical structure intersection on different planes.
Preferably, the first oil groove structure is arranged in parallel in the axial direction of the piston pin hole, and the second oil groove structure is arranged in the circumferential direction of the piston pin hole; the midpoint of the first lubricating oil groove structure and the midpoint of the second lubricating oil groove structure along the length direction are respectively arranged at two ends of the cross section diameter of the piston pin hole.
Preferably, an inner ring welding line and an outer ring welding line are arranged between the forged steel piston top and the forged steel piston skirt, and the inner ring welding line and the outer ring welding line are respectively positioned on different height lines.
The manufacturing method of the forged steel piston comprises the following steps:
s1, processing a forged steel piston top: (1) the forged steel piston crown is formed by die forging; (2) normalizing the mixture; (3) rough machining; and (4) quenching and tempering: (5) semi-finishing;
s2, processing steps of forged steel piston skirt: (1) forging and forming the forged steel piston skirt: (2) normalizing the mixture; (3) rough machining: (4) tempering; and (5) semi-finishing:
s3, assembling the forged steel piston crown and the forged steel piston skirt after the treatment in the steps S1 and S2: and the forged steel piston crown and the forged steel piston skirt are subjected to inertia friction welding by an inertia friction welding machine.
S4, the processing steps of the forged steel piston welded and molded in the step S3 are as follows: (1) high temperature tempering; (2) ultrasonic flaw detection; (3) finely turning the ring groove; (4) laser quenching; (5) boring a piston pin hole; (6) Milling a first lubrication groove structure and a second lubrication groove structure which are vertically intersected; (7) finish turning the head; (8) a finished vehicle type; (9) finely boring a piston pin hole; (10) fine grinding ring grooves: (11) deburring and cleaning; (12) surface treatment.
The manufacturing method of the forged steel piston comprises the following specific detailed steps:
1. the processing steps of the forged steel piston top are as follows: the forged steel piston crown is formed by die forging, and the forged steel piston crown is specifically: heating round steel to 1160-1180 ℃ and discharging, and performing free forging and upsetting twice to ensure that the total upsetting ratio is more than or equal to 3, blowing off oxide skin, and finishing blank making; (2) Placing the die at the center of the die, wherein the initial forging temperature is 1160 ℃ and the final forging temperature is 950 ℃; (3) Then normalizing, namely heating to 880 ℃, and preserving heat for 3 hours; (4) rough turning the combustion surface; (5) Ultrasonic flaw detection is carried out on the piston top by using a phased array flaw detector with 2mm equivalent flat bottom hole reflected waves as a standard; (6) rough turning the cooling surface; and (7) quenching and tempering: heating the forged steel piston crown after rough turning of the cooling surface to 860 ℃, preserving heat for 3 hours, and quenching K oil by a multipurpose furnace under atmosphere protection, wherein the oil temperature is 60-80 ℃; heating to 590-600 ℃ by using an atmosphere protection furnace, preserving heat for 3h, and tempering at high temperature; (8) finish turning the combustion surface; (9) finish turning the cooling surface; (10) magnetic powder inspection; (11) cleaning the finished forged steel piston crown; (12) final inspection of the forged steel piston crown;
2. the processing steps of the forged steel piston skirt are as follows: the forged steel piston skirt is formed by forging, and the forged steel piston skirt is concretely as follows: the round steel is heated to 1160-1180 ℃ and discharged from the furnace, and is subjected to free forging and upsetting twice, so that the total upsetting ratio is more than or equal to 3, oxide skin is blown off, and blank making is completed; (2) Placing the die at the center of the die, wherein the initial forging temperature is 1160 ℃ and the final forging temperature is 950 ℃; (3) Then normalizing, namely heating to 880 ℃, and preserving heat for 3 hours; (4) rough boring a piston pin hole; and (5) quenching and tempering: heating the forged steel piston skirt after rough boring the piston pin hole to 860 ℃, preserving heat for 3 hours, and quenching K oil by a multipurpose furnace with atmosphere protection, wherein the oil temperature is 60-80 ℃; heating to 590-600 ℃ by using an atmosphere protection furnace, preserving heat for 3h, and tempering at high temperature; (6) shot blasting; (7) turning the end face of the spigot; (8) a vehicle head portion; (9) scribing: (10) boring a piston pin hole; (11) drilling an oil hole; (12) deburring sharp corners; (13) magnetic powder inspection; (14) cleaning the finished forged steel piston skirt; (15) final inspection of the forged steel piston skirt;
3. assembly of forged steel piston crown and forged steel piston skirt after treatment via steps S1 and S2: the piston crown after semi-finishing and the forged steel piston skirt after semi-finishing are clamped by an elastic chuck with a taper sleeve for centering, the spigot end of the forged steel piston skirt and the sleeve diameter end of the forged steel piston crown, and a motor of a certain inertia friction welding machine is utilized to drive an eccentric wheel to rotate in an accelerating way, when the fixed rotating speed reaches 850rpm, the moment of inertia is fixed to be 338kg.m 2 The welding energy is constant; by virtue of the advantages of high welding energy and no liquid metallurgical air holes and crack defects of the inertia friction welding, the high-quality and high-efficiency welding of the forged steel piston crown and the forged steel piston skirt is realized.
4. The forged steel piston welded and formed in the step S3 is processed: (1) high temperature tempering: heating the forged steel piston to 570-580 ℃ in an atmosphere furnace, preserving heat for 3h, cooling the atmosphere furnace to below 180 ℃, discharging and air cooling; (2) Ultrasonic flaw detection is carried out on the welding seam of the forged steel piston by using a phased array flaw detector, and reflected waves of a 2mm equivalent flat bottom hole are selected; (3) checking and oiling; (4) finely turning the outer circle of the forged steel piston; (5) semi-finish turning the forged steel piston head; (6) rough boring a piston pin hole; (7) finish milling the spigot end; (8) drilling a lifting hole; (9) finely turning the ring groove; (10) laser quenching of the ring groove; (11) semi-fine boring the piston pin hole; (12) Milling a first lubrication groove structure and a second lubrication groove structure which are vertically intersected; (13) finish turning the head; (14) finish turning the molded line; (15) finely boring a piston pin hole; (16) refining the ring groove; (17) a counterweight; (18) deburring; (19) magnetic powder inspection; (20) cleaning; final inspection (21); (22) phosphating; (23) graphitizing; (24) marking; and (25) final inspection (II).
By adopting the technical scheme, the invention has the following beneficial effects:
(1) According to the invention, a connection mode of the forged steel piston crown and the forged steel piston skirt through inertia friction welding is adopted, so that the problem that the traditional piston is difficult to bear explosion pressure of more than 25MPa is solved, and the application requirement of a high-strength diesel engine is further met;
(2) According to the invention, the inner ring welding seam and the outer ring welding seam between the forged steel piston top and the forged steel piston skirt adopt the structural design of unequal-height welding seams, so that the problem that the welding seam hemming influences the cooling of oil in the piston cooling cavity is solved, the oil in the piston cooling cavity can have a good cooling effect, and further the forged steel piston can bear higher thermal load;
(3) The forged steel piston skirt and the forged steel piston crown are connected by inertia friction welding, so that the characteristic parts of bolted connection such as counter bores of the traditional forged steel piston skirt are reduced; compared with a steel top aluminum skirt bolt-connected piston, the weight is basically kept unchanged, and the total length is reduced by about 16%; compared with a steel top iron skirt bolt-connected piston, the weight is reduced by about 30 percent, and the total length is reduced by about 35 percent.
(4) The invention creatively provides a first lubrication oil groove structure and a second lubrication oil groove structure which are intersected vertically at the piston pin hole part, and through the structural design, a good lubrication and cooling effect can be achieved, and the problem that the small end holes of the piston pin hole, the piston pin and the connecting rod are easy to generate dry friction and occlusion is solved, so that a good lubrication and cooling effect is achieved in the piston pin hole, and the service lives of the piston pin hole and the piston pin are prolonged; meanwhile, the oil grooves with the structural design can ensure that lubricating oil is better uniformly distributed in the piston pin holes, and the lubricating effect is better achieved by the minimum number of oil grooves under the condition of ensuring the overall strength of the piston.
(5) In the manufacturing method of the forged steel piston, after the inertia friction welding is finished, the forged steel piston is subjected to high-temperature tempering treatment, so that the mechanical property of the welding line position can be ensured to be consistent with that of the piston material, and the mechanical property of the whole piston is improved.
Drawings
In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments that are illustrated in the appended drawings, in which:
FIG. 1 is a schematic view of a forged steel piston according to the present invention;
FIG. 2 is a cross-sectional view of the forged steel piston of the present invention taken along the cross-section of the piston pin bore;
FIG. 3 is a schematic structural view of a forged steel piston crown according to the present invention;
FIG. 4 is a schematic view of the forged steel piston skirt of the present invention;
fig. 5 is a cross-sectional view of a forged steel piston skirt according to the present invention taken along a cross-section of a piston pin bore.
In the figure, a 1-wrought steel piston crown; 11-an inner ring connecting surface; 12-an outer ring connecting surface; 13-combustion face; 14-diameter of the sleeve; 15-cooling surface; 2-forging a steel piston skirt; 21-an inner race receiving surface; 22-an outer ring bearing surface; 23-spigot end; 24-oil holes; 3-inner ring weld joints; 4-an outer ring welding line; 5-piston pin holes; 6-a first lubrication groove structure; 7-a second lubrication groove structure.
Detailed Description
The technical scheme of the invention is described in detail below through the drawings, but the protection scope of the invention is not limited to the embodiments.
Examples: the large-cylinder-diameter forged steel piston comprises a forged steel piston top 1, a forged steel piston skirt 2 and a piston pin hole 5, wherein the forged steel piston top 1 and the forged steel piston skirt 2 are connected through inertia friction welding, and as shown in fig. 3, 4 and 5, the forged steel piston top 1 in the embodiment comprises an inner ring connecting surface 11, an outer ring connecting surface 12, a combustion surface 13, a sleeve diameter 14 and a cooling surface 13; the forged steel piston skirt 2 in the present embodiment includes an inner ring receiving surface 21 which is inertia friction welded with the inner ring connecting surface 11, an outer ring receiving surface 22 which is inertia friction welded with the outer ring connecting surface 12, a spigot end 23, and an oil hole 24; the welding seam between the inner ring connecting surface 11 and the inner ring bearing surface 21 in the embodiment is an inner ring welding seam 3, and the welding seam between the outer ring connecting surface 12 and the outer ring bearing surface 22 is an outer ring welding seam 4; the forged steel piston crown 1 and the forged steel piston skirt 2 are connected by inertia friction welding, so that the problem that the traditional piston cannot bear explosion pressure of more than 25MPa is solved, and the application requirement of a high-strength diesel engine is further met; and the inertia friction welding is adopted, so that the characteristic parts of bolted connection such as the counter bore of the traditional forged steel piston skirt are reduced, the weight of the bolted connection piston is reduced by about 30% compared with the weight of the bolted connection piston with the same diameter, and the total length can be reduced by about 20%. The inner ring welding seam 3 and the outer ring welding seam 4 in the embodiment are respectively positioned on different height lines, and the unequal height design of the inner ring welding seam 3 and the outer ring welding seam 4 solves the problem that the welding seam hemming affects the cooling of the oil in the cooling cavity of the forged steel piston, so that the oil in the cooling cavity has good cooling effect, and the forged steel piston can bear higher heat load.
As shown in fig. 1 and 2, the piston pin hole 5 in the present embodiment is provided with a first oil groove structure 6 and a second oil groove structure 7, and the length setting directions of the first oil groove structure 6 and the second oil groove structure 7 are intersected in different planes in a vertical structure; the first oil groove structure 6 is arranged in parallel in the axial direction of the piston pin hole 5, the second oil groove structure 7 is arranged in the circumferential direction of the piston pin hole 5, and the other end of the diameter of the piston pin hole 5 corresponding to the midpoint of the first oil groove structure 6 in the embodiment is the midpoint of the second oil groove structure 7; in this embodiment, the middle point of the first lubricating oil groove structure 6 extends parallel to the axial direction of the piston pin hole 5, and the extending line of the first lubricating oil groove structure and the extending line of the second lubricating oil groove structure 7 extending parallel to the longitudinal direction of the piston pin hole 5 are in a perpendicular structure; in this embodiment, through setting up the first lubrication groove structure and the second lubrication groove structure of "perpendicular meeting", solved piston pin hole, wrist pin, connecting rod tip hole and easily take place the trouble of dry friction interlock, have well lubrication cooling effect.
The manufacturing method of the forged steel piston comprises the following steps:
s1, processing a forged steel piston top: the forged steel piston crown is formed by die forging, and the forged steel piston crown is specifically: heating round steel to 1160-1180 ℃ and discharging, and performing free forging and upsetting twice to ensure that the total upsetting ratio is more than or equal to 3, blowing off oxide skin, and finishing blank making; (2) Placing the die at the center of the die, wherein the initial forging temperature is 1160 ℃ and the final forging temperature is 950 ℃; (3) Then normalizing, namely heating to 880 ℃, and preserving heat for 3 hours; (4) rough turning the combustion surface; (5) Ultrasonic flaw detection is carried out on the piston top by using a phased array flaw detector with 2mm equivalent flat bottom hole reflected waves as a standard; (6) rough turning the cooling surface; and (7) quenching and tempering: heating the forged steel piston crown after rough turning of the cooling surface to 860 ℃, preserving heat for 3 hours, and quenching K oil by a multipurpose furnace under atmosphere protection, wherein the oil temperature is 60-80 ℃; heating to 590-600 ℃ by using an atmosphere protection furnace, preserving heat for 3h, and tempering at high temperature; (8) finish turning the combustion surface; (9) finish turning the cooling surface; (10) magnetic powder inspection; (11) cleaning the finished forged steel piston crown; (12) final inspection of the forged steel piston crown;
s2, processing steps of forged steel piston skirt: the forged steel piston skirt is formed by forging, and the forged steel piston skirt is concretely as follows: the round steel is heated to 1160-1180 ℃ and discharged from the furnace, and is subjected to free forging and upsetting twice, so that the total upsetting ratio is more than or equal to 3, oxide skin is blown off, and blank making is completed; (2) Placing the die at the center of the die, wherein the initial forging temperature is 1160 ℃ and the final forging temperature is 950 ℃; (3) Then normalizing, namely heating to 880 ℃, and preserving heat for 3 hours; (4) rough boring a piston pin hole; and (5) quenching and tempering: heating the forged steel piston skirt after rough boring the piston pin hole to 860 ℃, preserving heat for 3 hours, and quenching K oil by a multipurpose furnace with atmosphere protection, wherein the oil temperature is 60-80 ℃; heating to 590-600 ℃ by using an atmosphere protection furnace, preserving heat for 3h, and tempering at high temperature; (6) shot blasting; (7) turning the end face of the spigot; (8) a vehicle head portion; (9) scribing: (10) boring a piston pin hole; (11) drilling an oil hole; (12) deburring sharp corners; (13) magnetic powder inspection; (14) cleaning the finished forged steel piston skirt; (15) final inspection of the forged steel piston skirt;
s3, assembling the forged steel piston crown and the forged steel piston skirt after the treatment in the steps S1 and S2: the piston crown after semi-finishing and the forged steel piston skirt after semi-finishing are clamped by an elastic chuck with a taper sleeve for centering, the spigot end of the forged steel piston skirt and the sleeve diameter end of the forged steel piston crown, and a motor of a certain inertia friction welding machine is utilized to drive an eccentric wheel to rotate in an accelerating way, when the fixed rotating speed reaches 850rpm, the moment of inertia is fixed to be 338kg.m 2 The welding energy is constant; by virtue of the advantages of high welding energy and no liquid metallurgical air holes and crack defects of the inertia friction welding, the high-quality and high-efficiency welding of the forged steel piston crown and the forged steel piston skirt is realized.
S4, processing the forged steel piston welded and molded in the step S3: (1) high temperature tempering: heating the forged steel piston to 570-580 ℃ in an atmosphere furnace, preserving heat for 3h, cooling the furnace to below 180 ℃, discharging and air cooling; (2) Ultrasonic flaw detection is carried out on the welding seam of the forged steel piston by using a phased array flaw detector, and reflected waves of a 2mm equivalent flat bottom hole are selected; (3) checking and oiling; (4) finely turning the outer circle of the forged steel piston; (5) semi-finish turning the forged steel piston head; (6) rough boring a piston pin hole; (7) finish milling the spigot end; (8) drilling a lifting hole; (9) finely turning the ring groove; (10) laser quenching of the ring groove; (11) semi-fine boring the piston pin hole; (12) Milling a first lubrication groove structure and a second lubrication groove structure which are vertically intersected; (13) finish turning the head; (14) finish turning the molded line; (15) finely boring a piston pin hole; (16) refining the ring groove; (17) a counterweight; (18) deburring; (19) magnetic powder inspection; (20) cleaning; final inspection (21); (22) phosphating; (23) graphitizing; (24) marking; and (25) final inspection (II).
In the step S4 in the embodiment, after the inertia friction welding is finished, the forged steel piston is subjected to high-temperature tempering treatment, so that the mechanical properties of the welding line position can be ensured to be consistent with those of the piston material; in the prior art, the weight and the total length of a steel top aluminum skirt bolt connecting piston with the cylinder diameter similar to that of the forged steel piston in the embodiment are respectively 9.6-9.7kg and 190+/-0.2 mm, and the weight and the total length of a steel top iron skirt bolt connecting piston are respectively 14.1-14.3kg and 248.7+/-0.2 mm; the weight of the forged steel piston in the embodiment is 9.8-9.9kg, and the total length is 160+/-0.2 mm; compared with the existing steel top aluminum skirt bolt-connected piston, the weight is basically kept unchanged, and the total length is reduced by about 16%; compared with a steel top iron skirt bolt-connected piston, the weight is reduced by about 30 percent, and the total length is reduced by about 35 percent; overall, the forged steel piston of the present embodiment has significant weight and overall length advantages.
By using the manufacturing method of the forged steel piston in the embodiment, the piston meeting the working condition requirement that the maximum explosion pressure of the diesel engine exceeds 25MPa is manufactured, and the inner ring welding seam and the outer ring welding seam between the forged steel piston crown and the forged steel piston skirt in the embodiment adopt the structural design of unequal-height welding seams, so that the problem that the welding seam hemming affects the cooling of the oil in the cooling cavity of the piston is solved, the oil in the cooling cavity of the piston can have good cooling effect, and further the forged steel piston can bear higher heat load.
As described above, although the present invention has been shown and described with reference to certain preferred embodiments, it is not to be construed as limiting the invention itself. Various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (8)
1. The large-cylinder-diameter forged steel piston comprises a forged steel piston top and a forged steel piston skirt, and is characterized in that the forged steel piston top is connected with the forged steel piston skirt through inertia friction welding, a first lubricating oil groove structure and a second lubricating oil groove structure are arranged in a piston skirt pin hole, and the length setting directions of the first lubricating oil groove structure and the second lubricating oil groove structure are vertical structures on different planes;
the first lubrication oil groove structure is arranged in parallel in the axis direction of the piston pin hole, the second lubrication oil groove structure is arranged in the circumferential direction of the piston pin hole, and the midpoints of the first lubrication oil groove structure and the second lubrication oil groove structure along the length direction are respectively arranged at two ends of the cross section diameter of the piston pin hole.
2. A large bore wrought steel piston according to claim 1, wherein an inner ring weld and an outer ring weld are included between the wrought steel piston crown and the wrought steel piston skirt, the inner ring weld and the outer ring weld being located at different elevation lines, respectively.
3. A method of manufacturing a wrought steel piston according to claim 1, comprising the steps of:
s1, processing a forged steel piston top: (1) the forged steel piston crown is formed by die forging; (2) normalizing the mixture; (3) rough machining; and (4) quenching and tempering: (5) semi-finishing;
s2, processing steps of forged steel piston skirt: (1) forging and forming the forged steel piston skirt: (2) normalizing the mixture; (3) rough machining: (4) tempering; and (5) semi-finishing:
s3, assembling the forged steel piston crown and the forged steel piston skirt after the treatment in the steps S1 and S2: the forging steel piston crown and the forging steel piston skirt are subjected to inertia friction welding by an inertia friction welding machine;
s4, the processing steps of the forged steel piston welded and molded in the step S3 are as follows: (1) high temperature tempering; (2) ultrasonic flaw detection; (3) finely turning the ring groove; (4) laser quenching; (5) boring a piston pin hole; (6) Milling a first lubrication groove structure and a second lubrication groove structure which are vertically intersected; (7) finish turning the head; (8) a finished vehicle type; (9) finely boring a piston pin hole; (10) fine grinding ring grooves: (11) deburring and cleaning; (12) surface treatment.
4. A method of manufacturing a forged steel piston according to claim 3, wherein the step (1) of steps S1 and S2 is specifically: heating round steel to 1160-1180 ℃ and discharging, and performing free forging and upsetting twice to ensure that the total upsetting ratio is more than or equal to 3, blowing off oxide skin, and finishing blank making; placed in the center of the die, the initial forging temperature is 1160 ℃ and the final forging temperature is 950 ℃.
5. A method of manufacturing a forged steel piston according to claim 3, wherein the tempering of step (4) of steps S1 and S2 is specifically: heating to 860 ℃, preserving heat for 3 hours, and quenching K oil by a multipurpose furnace under atmosphere protection, wherein the oil temperature is 60-80 ℃; and then heating to 590-600 ℃ by using an atmosphere protection furnace, preserving heat for 3h, and tempering at high temperature.
6. A method of manufacturing a wrought steel piston according to claim 3, wherein the normalizing treatment in steps S1 and S2 is heating to 880 ℃, holding for 3 hours.
7. A method of manufacturing a forged steel piston according to claim 3, wherein in said step S3, the motor in said inertia friction welder is fixed at 850rpm and the moment of inertia is fixed at 338kg.m 2 The welding energy of the inertia friction welding machine between the forged steel piston top and the forged steel piston skirt is constant, and the high-quality and high-efficiency welding of the forged steel piston top and the forged steel piston skirt is realized by virtue of the advantages of high welding energy and no liquid metallurgical air holes and crack defects of the inertia friction welding machine.
8. A method of manufacturing a forged steel piston according to claim 3, wherein step (1) in step S3 is: and (3) putting the forged steel piston into an atmosphere furnace, heating to 570-580 ℃, preserving heat for 3 hours, cooling the atmosphere furnace to below 180 ℃, and discharging and air cooling.
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