A method for processing a remelting copper sleeve-inlaid piston and a remelting copper sleeve-inlaid piston

Abstract

The present application provides a method for processing a remelted copper sleeve-inserted piston and a remelted copper sleeve-inserted piston, comprising the following steps: using a multi-channel sequential controlled cooling and solidification process technology of aluminum liquid to cast a piston blank; rough turning a positioning stop: rough turning a flat top surface of a combustion chamber; boring a bottom hole, and boring a piston pin hole into an arc shape with a top surface positioning, with an arc drop of 0.04mm-0.08mm, and an interference with the copper sleeve of 0.08mm-0.12mm; keeping the piston warm at 100°C-150°C for 2-4 hours; using a plasma beam to remelt the throat area of ​​the combustion chamber; using the piston body surface temperature of 150°C-200°C after the piston is remelted to perform copper sleeve assembly; heating the piston body to 160°C-180°C after cooling it, and keeping it warm for 4-6 hours; and fine machining to the finished product size. The present invention effectively refines the piston grains, strengthens the local strength of the combustion chamber throat, obtains good heat resistance and mechanical fatigue performance under high stress and high temperature conditions, improves the performance of the whole machine, has a simple preparation method and low manufacturing cost.

Description

Technical Field

[0001] The present application relates to the technical field of internal combustion engine equipment, and more specifically, to a method for processing a remelting copper-sleeved piston, and also to a remelting copper-sleeved piston. Background Art

[0002] In an internal combustion engine, the piston is the largest reciprocating component in the cylinder. It has the harshest working conditions and the highest working intensity. It is subject to high thermal load, mechanical load and strong wear. It is often in high temperature, high load, high speed, poor lubrication and difficult cooling. It is prone to various failures, which directly affect the performance, economy, reliability and durability of the whole machine. With the increasingly stringent emission regulations, the cylinder explosion pressure of some diesel engines has reached more than 18MPa. The mechanical and thermal loads borne by diesel engine pistons have been greatly improved compared with the past. In order to ensure the reliability of diesel engine pistons and the whole machine, new types of pistons should be continuously developed for diesel engine pistons to meet the requirements of high explosion pressure and high thermal load.

[0003] Regarding the processing technology of the piston, the application number is 201710612103.7, which adopts the manufacturing of the piston blank → preheating treatment of the piston blank → remelting treatment of the throat remelting part → rapid cooling treatment → subsequent processing of the piston. The piston is directly placed in water for rapid cooling, which leads to the risk of brittle cracking of the piston. In addition, in the piston processing technology of the application number 201110183912.3, the processing technology of the piston blank is rough processing → remelting → natural air cooling → fine processing. The air cooling natural cooling process leads to insufficient grain refinement. The obtained extremely fine structure can effectively prevent the formation of fatigue cracks in the piston throat during operation under high temperature and high pressure, and extend the service life of the piston. Summary of the invention

[0004] The present application provides a method for processing a remelting copper sleeve piston, which refines the piston grains, strengthens the local strength of the combustion chamber throat, obtains good heat resistance and mechanical fatigue performance under high stress and high temperature conditions, and improves the performance of the whole machine. The present application also provides a remelting copper sleeve piston obtained by the remelting copper sleeve piston processing method, which has high strength, good performance and low cost.

[0005] The present application provides a method for processing a remelting copper sleeve piston, comprising the following steps:

[0006] S1. Piston blank forming: The piston blank is cast by using aluminum liquid multi-channel sequential controlled cooling and solidification technology;

[0007] S2, rough turning positioning stop: used for positioning during rough turning of the combustion chamber and remelting process;

[0008] S3. Rough turning of the flat top surface of the combustion chamber: Rough turning of the top surface of the combustion chamber to provide a positioning surface for subsequent bottom boring;

[0009] S4, Bore the bottom hole: Use the top surface to position the piston pin hole into an arc shape, with an arc drop of 0.04mm to 0.08mm, and an interference fit of 0.08mm to 0.12mm with the copper sleeve;

[0010] S5, insulation: keep the piston at 100℃~150℃ for 2~4 hours;

[0011] S6, Piston remelting: Use plasma beam to remelt the combustion chamber throat area;

[0012] S7, copper sleeve assembly: the copper sleeve assembly is performed by taking advantage of the piston surface temperature of 150°C to 200°C after the piston is remelted;

[0013] S8, stress relief: after cooling the piston body, heat it to 160℃~180℃ and keep it warm for 4~6 hours;

[0014] S9, finishing: finishing to finished product size.

[0015] In some embodiments, step S6: piston remelting: using a plasma beam to remelt the throat area of ​​the combustion chamber, the plasma beam is 2mm to 5mm away from the surface of the piston body, the voltage is 20V to 50V, the main arc current is 60A to 180A, the protective gas argon is 2L / min to 5L / min, the surface temperature of the piston after remelting is 150℃ to 200℃, and the remelting depth is 3mm to 10mm.

[0016] In some embodiments, the copper sleeve is placed in liquid nitrogen to cool during the piston remelting process, and then the piston is cooled by the process of the copper sleeve returning to normal temperature.

[0017] In some embodiments, the machining allowance of the combustion chamber throat is 2mm to 6mm, the machining allowance from the upper side wall of the throat to the flat top surface of the combustion chamber is 1.5mm to 5mm, and the machining allowance from the lower side wall of the throat to the bottom of the combustion chamber is 1mm to 4mm.

[0018] The remelted copper sleeved piston provided by the present application adopts a special process to strengthen the throat area of ​​the combustion chamber. The process is to obtain an extremely fine structure by cooling and solidifying the throat of the combustion chamber after a remelting process, thereby strengthening the local strength of the throat of the combustion chamber and obtaining good heat resistance and mechanical fatigue properties under high stress and high temperature conditions. The use of this technology reduces the cracking tendency of the combustion chamber to a minimum. The copper sleeve is interference-nested on the piston pin hole. The arc drop of the copper sleeve and the piston pin hole is 0.04mm~0.08mm, and the assembly interference between the copper sleeve and the piston pin hole is 0.08mm~0.12mm, which improves the wear resistance of the pin hole and the ability to withstand the alternating stress given by the piston pin. The present application effectively improves the disadvantages of traditional air cooling or water cooling.

[0019] In addition, the present application also provides a remelted copper sleeve-inlaid piston obtained by applying the above-mentioned additive method, including a piston body, a piston pin hole penetrating the piston body is opened on the pin seat of the piston body, a copper sleeve is installed in the piston pin hole with interference fit, the piston pin hole and the copper sleeve are arc-shaped, the arc drop is 0.04mm~0.08mm, and the interference fit with the copper sleeve is 0.08mm~0.12mm.

[0020] The remelted copper sleeve-inlaid piston provided in the present application has a piston pin hole and a copper sleeve in the shape of an arc, and the arc drop is 0.04mm to 0.08mm. The copper sleeve is inlaid in the piston pin hole, and the copper sleeve and the piston pin hole are interference fit, and the interference amount of the copper sleeve is 0.08mm to 0.12mm, which can improve the firmness of the installation of the copper sleeve and the piston pin hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0022] Figure 1 A cross-sectional view of a remelted copper sleeved piston provided in this application;

[0023] Figure 2 A schematic diagram of the copper sleeve of the remelted copper sleeve piston provided in this application;

[0024] Figure 3 for Figure 1 Another angle showing the schematic diagram of the piston pin hole;

[0025] Figure 4 for Figure 3 Schematic diagram of the copper sleeve in the middle assembly;

[0026] Figure 5 for Figure 3 A partial enlarged view of .

[0027] Among them, 1-piston blank, 2-combustion chamber, 3-piston pin hole, 4-combustion chamber, 5-copper sleeve; 41-throat. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] Please refer to Figures 1 to 5 , Figure 1 A cross-sectional view of a remelted copper sleeved piston provided in this application; Figure 2 A schematic diagram of the copper sleeve of the remelted copper sleeve piston provided in this application; Figure 3 for Figure 1 Another angle showing the schematic diagram of the piston pin hole; Figure 4 for Figure 3 Schematic diagram of the copper sleeve 5 in the middle assembly; Figure 5 for Figure 3 A partial enlarged view of .

[0030] In order to ensure the reliability of diesel engine piston and the whole machine and meet the requirements of high heat load and high mechanical load of the engine, the aluminum piston of the diesel engine needs to withstand the explosion pressure below 18-20MPa, and the combustion chamber 4 throat 41 and the pin hole copper sleeve 5 need to be strengthened on the basis of improving alloy performance, optimizing casting process and refining metallographic structure. Strengthening the combustion chamber 4 throat 41 is to strengthen the combustion chamber 4 throat 41 area by a special process. This process is to obtain extremely fine structure by cooling and solidifying the combustion chamber 4 throat 41 for one week after remelting process, thereby strengthening the local strength of the combustion chamber 4 throat 41, and obtaining good heat resistance and mechanical fatigue performance under high stress and high temperature conditions. The use of this technology reduces the cracking tendency of the combustion chamber 4 to the minimum; the piston pin hole copper sleeve 5 is to embed the copper sleeve 5 on the piston pin hole 3 to improve the wear resistance of the piston pin hole and the ability to withstand the alternating stress given by the piston pin, wherein the copper sleeve 5 and the piston pin hole 3 are interference fit.

[0031] The present application provides a method for processing a remelting copper sleeve piston, comprising the following steps:

[0032] S1. Forming piston blank 1: Piston blank 1 is cast by using aluminum liquid multi-channel sequential controlled cooling and solidification process technology;

[0033] S2, rough turning positioning stop: used for rough turning of the combustion chamber 4 and positioning during the remelting process;

[0034] S3, rough turning the flat top surface of the combustion chamber 4: rough turning the top surface of the combustion chamber 4 to provide a positioning surface for subsequent bottom boring;

[0035] S4, boring the bottom hole: Boring the pin hole into an arc shape with the top surface positioned, the arc drop is 0.04mm~0.08mm, and there is an interference fit of 0.08mm~0.12mm with the copper sleeve 5;

[0036] S5, heat preservation: keep the piston body 2 at 100°C to 150°C for 2 to 4 hours;

[0037] S6, piston remelting: using a plasma beam to remelt the throat 41 area of ​​the combustion chamber 4;

[0038] S7, copper sleeve 5 assembly: after the piston is remelted, the piston surface temperature is 150°C to 200°C, and the copper sleeve 5 is assembled;

[0039] S8, stress relief: after cooling the piston body 2, heat it up to 160°C to 180°C and keep it at this temperature for 4 to 6 hours to remove the stress in the remelting process and the interference assembly process of the copper sleeve 5;

[0040] S9, finishing: finishing to finished product size.

[0041] In step S1 , a piston blank 1 is formed by casting aluminum liquid using a multi-path sequential controlled cooling and solidification process, and the excess at the combustion chamber 4 is reduced.

[0042] In step S4, the arc drop of the piston pin hole 3 is 0.04-0.08 mm, and the interference between the piston pin hole 3 and the copper sleeve 5 is 0.08-0.12 mm, which can ensure that the copper sleeve 5 does not move after assembly and prevent the copper sleeve 5 from falling off during operation and affecting engine performance.

[0043] In the heat-retaining process of step S5, the piston body 2 is kept at a temperature of 100 to 150°C for 2 to 4 hours, thereby increasing the remelting depth.

[0044] In step S8, the piston body 2 is cooled and then heated to 160°C to 180°C for 4 to 6 hours, which can remove the internal stress of the piston body 2 and the stress in the remelting process and the interference assembly process of the copper sleeve 5.

[0045] In step S6 of the piston remelting process: a plasma beam is used to remelt the throat 41 area of ​​the combustion chamber 4, the plasma beam is 2mm to 5mm away from the surface of the piston body 2, the voltage is 20V to 50V, the main arc current is 60A to 180A, the protective gas is argon 2L / min to 5L / min, the surface temperature of the piston after remelting is 150°C to 200°C, and the remelting depth H is 3mm to 10mm.

[0046] During the piston remelting process in step S7, the copper sleeve 5 is placed in liquid nitrogen to cool down using the high temperature of the piston after remelting, and then the piston is cooled down using the process of the copper sleeve 5 returning to normal temperature, so that the copper sleeve 5 is assembled and the piston is cooled quickly.

[0047] When the combustion chamber 4 is rough turned, the machining allowance changes with the change of the throat 41 of the combustion chamber 4, wherein the machining allowance L1 of the throat 41 of the combustion chamber 4 is 2mm~6mm, the machining allowance L2 from the upper side wall of the throat 41 to the flat top surface of the combustion chamber 4 is 1.5mm~5mm, and the machining allowance L3 from the lower side wall of the throat 41 to the bottom of the combustion chamber 4 is 1mm~4mm. The top surface of the combustion chamber 4 is then rough turned to provide a positioning surface for the subsequent boring of the bottom hole.

[0048] The present application also provides a remelted copper sleeve-inlaid piston, comprising a piston body 2, a piston pin hole 3 penetrating the piston body 2 is opened on the pin seat of the piston body 2, a copper sleeve 5 is installed in the piston pin hole 3 with interference fit, the hole wall of the piston pin hole 3 and the outer circumferential surface of the copper sleeve 5 are both arc-shaped, the arc drop is 0.04mm~0.08mm, and the interference fit with the copper sleeve 5 is 0.08mm~0.12mm.

[0049] The piston pin hole 3 and the copper sleeve 5 in this application both have a certain curvature, and the drop is 0.04-0.08mm, which can ensure that the copper sleeve 5 does not move after assembly, and prevent the copper sleeve 5 from falling off during operation and affecting the engine performance. At the same time, there is an interference of 0.08-0.12mm between the copper sleeve 5 and the piston pin hole 3. Due to the certain curvature and interference fit, the difficulty of assembly increases. Therefore, a single piston heating or copper sleeve 5 cooling cannot meet the assembly requirements. This application adopts a piston surface temperature of 200°C after the piston is remelted, and the copper sleeve 5 is cooled at the same time, forming a temperature difference of 360-420°C, which can easily assemble the copper sleeve 5.

[0050] It should be noted that, in this specification, relational terms such as first and second are merely used to distinguish one entity from other entities, but do not necessarily require or imply any actual relationship or order between these entities.

[0051] The above is a detailed introduction to the remelting copper sleeve piston processing method and the remelting copper sleeve piston provided by the present application. This article uses specific examples to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core ideas of the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

Claims

1. A method for processing a remelting copper sleeve piston, characterized in that: The steps include: S1. Forming a piston blank (1): The piston blank (1) is cast by using a multi-path sequential controlled cooling and solidification process of molten aluminum; S2, rough turning positioning stop: used for rough turning of the combustion chamber (4) and positioning during the remelting process; S3. Rough turning of the flat top surface of the combustion chamber (4): Rough turning of the top surface of the combustion chamber (4) to provide a positioning surface for subsequent bottom boring; S4. Bore the bottom hole: Use the top surface to position the piston pin hole (3) into an arc shape with a drop of 0.04mm~0.08mm and an interference fit of 0.08mm~0.12mm with the copper sleeve (5); S5, insulation: keep the piston at 100℃~150℃ for 2~4 hours; S6, piston remelting: using a plasma beam to remelt the throat area of ​​the combustion chamber (4). When using a plasma beam to remelt the throat area of ​​the combustion chamber (4), the plasma beam is 2 mm to 5 mm away from the surface of the piston body (2), the voltage is 20 V to 50 V, the main arc current is 60 A to 180 A, and the protective gas is argon gas at 2 L / min to 5 L / min. After the piston is remelted, the surface temperature is 150° C. to 200° C., and the remelting depth is 3 mm to 10 mm. During the piston remelting process, the copper sleeve (5) is placed in liquid nitrogen for cooling, and then the piston is cooled by the process of the copper sleeve (5) returning to normal temperature; S7, copper sleeve (5) assembly: after the piston is remelted, the piston surface temperature is 150°C to 200°C, and the copper sleeve (5) is assembled; S8, stress relief: after cooling the piston body (2), heat it to 160°C to 180°C and keep it at this temperature for 4 to 6 hours; S9, finishing: finishing to finished product size.

2. The method for processing a remelting copper sleeve piston according to claim 1, characterized in that: The machining allowance of the throat of the combustion chamber (4) is 2 mm to 6 mm, the machining allowance from the upper side wall of the throat to the flat top surface of the combustion chamber (4) is 1.5 mm to 5 mm, and the machining allowance from the lower side wall of the throat to the bottom of the combustion chamber (4) is 1 mm to 4 mm.

3. A remelted copper sleeved piston obtained by the additive method according to any one of claims 1 to 2, comprising a piston body (2), a piston pin hole (3) penetrating the piston body (2), a copper sleeve (5) interference-fitted in the piston pin hole (3), characterized in that: The piston pin hole (3) and the copper sleeve (5) are in an arc shape, the arc drop is 0.04 mm to 0.08 mm, and the interference with the copper sleeve (5) is 0.08 mm to 0.12 mm.

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