CN110885920A - Method for strengthening exhaust valve seat of cylinder cover of special cast iron diesel engine - Google Patents
Method for strengthening exhaust valve seat of cylinder cover of special cast iron diesel engine Download PDFInfo
- Publication number
- CN110885920A CN110885920A CN201911035909.XA CN201911035909A CN110885920A CN 110885920 A CN110885920 A CN 110885920A CN 201911035909 A CN201911035909 A CN 201911035909A CN 110885920 A CN110885920 A CN 110885920A
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- CN
- China
- Prior art keywords
- strengthened
- valve seat
- working surface
- exhaust valve
- diesel engine
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/06—Surface hardening
- C21D1/09—Surface hardening by direct application of electrical or wave energy; by particle radiation
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/68—Temporary coatings or embedding materials applied before or during heat treatment
- C21D1/70—Temporary coatings or embedding materials applied before or during heat treatment while heating or quenching
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
Abstract
The invention discloses a special cast iron diesel engine cylinder cover exhaust valve seat strengthening method, which comprises the following steps: (1) removing oil stains on a working surface to be strengthened of a special cast iron diesel engine cylinder cover exhaust valve seat by using a cleaning agent; (2) uniformly coating the light absorption coating on a working surface to be strengthened; (3) placing the exhaust valve seat of the diesel engine cylinder cover coated with the coating on a workbench, and irradiating a working surface to be strengthened by laser beams in the vertical direction; (4) rotating an exhaust valve seat of a cylinder cover of the diesel engine or moving a laser beam, rapidly scanning a working surface to be strengthened by the laser beam, and heating the working surface to be strengthened to a temperature higher than a phase change point below a melting point to generate phase change hardening; (5) and (5) repeating the steps (2) - (4), uniformly coating a light absorption coating on the working surface to be strengthened, and carrying out second-layer laser strengthening to further increase the depth of the hardened layer so that the depth of the hardened layer is not less than 0.7 mm. By adopting the method, good working performance can be kept under the working environment of 350 ℃.
Description
Technical Field
The invention relates to a material surface modification method, in particular to a broadband laser solid-state phase change strengthening method for a special cast iron diesel engine cylinder cover exhaust valve seat.
Background
The diesel engine cylinder head valve seat is one of typical parts adopting cast iron. The existing diesel engine cylinder cover is cast by special cast iron, and comprises the following material components in percentage by mass: 0.20 to 0.35 Cr, 0.5 to 0.65 Ni, 0.35 to 0.55 Mo, 0.45 to 0.65 Cu, less than 0.12P, less than 0.10S, 2.9 to 3.5C, 1.4 to 2.1 Si, 0.75 to 1.20 Mn, 0.015 to 0.03 Sn, and the balance Fe. The valve seat and the cylinder cover are cast into a whole without independent air intake and exhaust valve seats. Such large components typically require complex manufacturing processes, precision machining, etc., require specialized equipment to produce, are expensive, and are costly. However, during the use process, the cast iron has large brittleness and poor wear resistance, so that a great amount of early failures are caused in the application, and the service life of the cast iron is limited. The laser solid phase transformation can cause the surface of the workpiece to generate phase transformation to obtain high hardness, has little heat influence on the matrix structure and small part deformation, can be directly applied to the manufacture of the exhaust valve seat, and has important significance for improving the working performance, saving resources and reducing the cost.
The area of a diesel engine cylinder cover exhaust valve seat required to be strengthened is a 12mm circular ring surface, in the existing laser solid-state phase change method, a circular light spot is used during laser solid-state phase change strengthening, the diameter of the light spot is generally 3mm, the width of the light spot is less than the width of a required strengthening zone, the light spot needs to be overlapped, the working efficiency is low, the problems of tempering soft zones and the like exist in the overlapped part, the strengthening effect is weakened, and cracks can be generated due to improper overlapping quantity control.
Disclosure of Invention
The invention aims to provide a broadband laser solid-state phase change strengthening method for a special cast iron diesel engine cylinder cover exhaust valve seat, which is simple in process control, high in efficiency and low in cost while effectively improving the surface wear resistance of the diesel engine cylinder cover exhaust valve seat.
The invention adopts the main technical scheme that:
a special cast iron diesel engine cylinder cover exhaust valve seat strengthening method comprises the following steps:
(1) removing oil stains on a working surface to be strengthened of a special cast iron diesel engine cylinder cover exhaust valve seat by using a cleaning agent;
(2) uniformly coating the light absorption coating on a working surface to be strengthened, wherein the coating thickness is 0.05-0.1 mm;
(3) placing the exhaust valve seat of the diesel engine cylinder cover coated with the coating on a workbench, and irradiating a working surface to be strengthened by laser beams in the vertical direction, wherein the size of the laser beams is (19-21) mm x (3-5) mm;
(4) rotating an exhaust valve seat of a cylinder cover of the diesel engine or moving a laser beam, rapidly scanning the working surface to be strengthened by the laser beam, heating the working surface to be strengthened to a temperature higher than a phase transition point below a melting point to generate phase transition hardening, so that the depth of a hardening layer is not less than 0.3mm, the laser power P is 2000-5000W, and the scanning speed V is 100-300 mm/min;
(5) and (5) repeating the steps (2) - (4), uniformly coating a light absorption coating on the working surface to be strengthened, and carrying out second-layer laser strengthening to further increase the depth of the hardened layer so that the depth of the hardened layer is not less than 0.7 mm.
The invention has the following advantages:
(1) the broadband laser phase change hardening is adopted, overlapping and softening areas are not needed, a large-area strengthening area with uniform structure performance can be obtained, the efficiency is high, and the deformation of workpieces is small.
(2) The exhaust valve seat of the diesel engine cylinder cover is a 45-degree inclined plane, the laser beam vertically irradiates the strengthening surface and forms an angle of 45 degrees with the strengthening surface, no tool is required to be manufactured, the process is simple and convenient, and the operation is easy.
(3) The double-layer laser solid phase change technology is adopted, the strengthening depth is effectively increased, defects such as air holes and cracks are avoided, and good working performance can be kept in a working environment at 350 ℃.
Drawings
FIG. 1 is a schematic laser processing diagram of the strengthening method of the exhaust valve seat of the special cast iron diesel engine cylinder cover.
Detailed Description
The present invention will be described in detail with reference to specific examples.
The broadband laser solid-state phase change strengthening technology adopts rectangular light spots and a broadband scanning mode, and because the width of a laser beam is greater than the width of the work piece required to be strengthened, the lapping is not needed, so that a softening area is avoided, the laser strengthening effect can be obviously improved, the high wear-resistant characteristic of the working surface of a part is realized, the problem that the service life and the working efficiency are influenced due to abrasion is solved, and meanwhile, the good use performance can be kept under the high-temperature working environment.
Based on the above principle, as shown in fig. 1, the method for strengthening the exhaust valve seat of the cylinder cover of the special cast iron diesel engine comprises the following steps:
(1) removing oil stain on the working surface to be strengthened of the exhaust valve seat of the special cast iron diesel engine cylinder cover by using a cleaning agent, wherein a conventional surface cleaning method such as alcohol cleaning can be adopted;
(2) uniformly coating the light absorption coating on a working surface to be strengthened, wherein the coating thickness is 0.05-0.1 mm (such as 0.05, 0.06, 0.1mm and the like) so as to effectively improve the light absorption rate of the surface of the workpiece to laser, and the light absorption coating can be conventional light absorption coating, such as TH-2 type light absorption coating developed by Qinghua university;
(3) placing the exhaust valve seat of the diesel engine cylinder cover coated with the coating on a workbench, irradiating a working surface to be strengthened by a laser beam along the vertical direction, wherein the size of the laser beam is (19-21) mm x (3-5) mm, such as 19 x 3mm, 21 x 4mm or 20 x 5mm, and the like, and because the exhaust valve seat of the diesel engine cylinder cover is a 45-degree inclined plane and the laser beam irradiates the working surface to be strengthened along the vertical direction, the laser beam forms an angle of 45 degrees with an area to be strengthened, and surface processing can be carried out without manufacturing a tool, as shown in fig. 1;
(4) the exhaust valve seat of the cylinder cover of the diesel engine rotates or the laser beam moves, the laser beam rapidly scans the working surface to be strengthened, the working surface to be strengthened is heated to the temperature of the phase transition point below the melting point, phase transition hardening is generated, the depth of a hardened layer is not less than 0.3mm, the laser power P is 2000-5000W (such as 2000W, 40000W, 5000W and the like), and the scanning speed V is 100-300 mm/min (such as 100mm/min, 200mm/min, 300mm/min and the like).
(5) And (5) repeating the steps (2) - (4), uniformly coating a light absorption coating on the working surface to be strengthened, and carrying out second-layer laser strengthening to further increase the depth of the hardened layer so that the depth of the hardened layer is not less than 0.7 mm.
The hardness of the exhaust valve seat of the special cast iron diesel engine cylinder cover treated by the method can reach HV581, the depth of a hardened layer reaches 0.7mm, and the exhaust valve seat can still keep good performance after a 350 ℃ tempering test.
Claims (1)
1. A special cast iron diesel engine cylinder cover exhaust valve seat strengthening method is characterized by comprising the following steps:
(1) removing oil stains on a working surface to be strengthened of a special cast iron diesel engine cylinder cover exhaust valve seat by using a cleaning agent;
(2) uniformly coating the light absorption coating on a working surface to be strengthened, wherein the coating thickness is 0.05-0.1 mm;
(3) placing the exhaust valve seat of the diesel engine cylinder cover coated with the coating on a workbench, and irradiating a working surface to be strengthened by laser beams in the vertical direction, wherein the size of the laser beams is (19-21) mm x (3-5) mm;
(4) rotating an exhaust valve seat of a cylinder cover of the diesel engine or moving a laser beam, rapidly scanning the working surface to be strengthened by the laser beam, heating the working surface to be strengthened to a temperature higher than a phase transition point below a melting point to generate phase transition hardening, so that the depth of a hardening layer is not less than 0.3mm, the laser power P is 2000-5000W, and the scanning speed V is 100-300 mm/min;
(5) and (5) repeating the steps (2) - (4), uniformly coating a light absorption coating on the working surface to be strengthened, and carrying out second-layer laser strengthening to further increase the depth of the hardened layer so that the depth of the hardened layer is not less than 0.7 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911035909.XA CN110885920A (en) | 2019-10-29 | 2019-10-29 | Method for strengthening exhaust valve seat of cylinder cover of special cast iron diesel engine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911035909.XA CN110885920A (en) | 2019-10-29 | 2019-10-29 | Method for strengthening exhaust valve seat of cylinder cover of special cast iron diesel engine |
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| Publication Number | Publication Date |
|---|---|
| CN110885920A true CN110885920A (en) | 2020-03-17 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201911035909.XA Pending CN110885920A (en) | 2019-10-29 | 2019-10-29 | Method for strengthening exhaust valve seat of cylinder cover of special cast iron diesel engine |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1757764A (en) * | 2005-10-25 | 2006-04-12 | 天津修船技术研究所 | Treatment method of laser solid state phase change hardening treatment of chromium molybdenum coper cast iron work piece |
| CN104846156A (en) * | 2015-04-17 | 2015-08-19 | 江苏大学 | Square light spot laser multilayer staggering impact uniform enhancement method |
| CN105039652A (en) * | 2015-04-29 | 2015-11-11 | 江苏大学 | Laser shock uniform enhancement method with square-shaped light spot used in curved surface |
-
2019
- 2019-10-29 CN CN201911035909.XA patent/CN110885920A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1757764A (en) * | 2005-10-25 | 2006-04-12 | 天津修船技术研究所 | Treatment method of laser solid state phase change hardening treatment of chromium molybdenum coper cast iron work piece |
| CN104846156A (en) * | 2015-04-17 | 2015-08-19 | 江苏大学 | Square light spot laser multilayer staggering impact uniform enhancement method |
| CN105039652A (en) * | 2015-04-29 | 2015-11-11 | 江苏大学 | Laser shock uniform enhancement method with square-shaped light spot used in curved surface |
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Application publication date: 20200317 |
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| RJ01 | Rejection of invention patent application after publication |