Up-and-down throat remelted piston and process

Abstract

The application discloses a kind of upper and lower throat remelting piston and process.It includes piston, the upper and lower throat remelting area of the upper throat remelting area and the lower throat remelting area of the upper combustion chamber area of the inner ring of the piston is equipped with interval, the top of the piston is equipped with multiple gas valve pits, the multiple gas valve pits include multiple exhaust pits and multiple intake pits, the multiple exhaust pits and multiple intake pits are evenly arranged along the center of circle of piston, the upper throat remelting area is located at the inner ring of multiple exhaust pits and multiple intake pits, the lower throat remelting area is located below the upper throat remelting area;The upper throat remelting area has the same remelting layer thickness around it.The upper throat remelting area of different depth gas valve pit of the application, argon arc welding gun axial movement is matched with corresponding gas valve pit depth, to ensure that the upper throat remelting area has the same remelting layer thickness around it.

Description

Technical Field

[0001] This invention belongs to the field of engine technology, specifically relating to a remelted piston with upper and lower throats and its manufacturing process. Background Technology

[0002] To meet increasingly stringent emission and fuel consumption requirements, diesel engine detonation pressure and exhaust temperature are also rising, and the mechanical and thermal loads on the pistons are increasing. Aluminum alloy pistons can no longer meet the requirements, and it is necessary to add remelting to the high-stress areas of the piston to improve the fatigue strength of the piston throat.

[0003] During the remelting process of the piston throat, the cooling rate is more than a thousand times that of the casting process. The microstructure of the aluminum alloy is transformed into very fine blocky primary silicon, dotted eutectic silicon and fine alloy phases, which are uniformly dispersed in the Al matrix. The microhardness of the remelted zone is significantly improved. The stress generated during the solidification process causes deformation of the Al matrix, increases the dislocation density, and forms a cellular network structure. The remelting process greatly improves the fatigue resistance of the aluminum alloy material.

[0004] Current technologies mainly involve adding a remelting process to the lower throat of the piston. However, due to the presence of valve pits in the upper throat area of ​​the piston, and the varying depths of each valve pit, it is impossible to guarantee the same remelting thickness around the upper throat. Therefore, the remelting of the upper throat of the aluminum piston remains unresolved. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a remelted piston with upper and lower throats and a process thereof.

[0006] The technical solution adopted in this invention is: a piston with upper and lower throat remelting, comprising a piston, wherein the upper and lower throats of the combustion chamber region on the inner ring of the piston are provided with spaced upper throat remelting areas and lower throat remelting areas, and the top of the piston is provided with multiple valve pits, the multiple valve pits including multiple exhaust pits and multiple intake pits, the multiple exhaust pits and multiple intake pits being evenly arranged along the center of the piston, the upper throat remelting area being located at the inner ring of the multiple exhaust pits and multiple intake pits, and the lower throat remelting area being located below the upper throat remelting area.

[0007] The plurality of exhaust pits and plurality of intake pits include a first exhaust valve pit, a second exhaust valve pit, a first intake valve pit, and a second intake valve pit, wherein the first exhaust valve pit, the second exhaust valve pit, the first intake valve pit, and the second intake valve pit are evenly arranged along the center of the piston.

[0008] The remelted layer thickness W1 is located around the upper throat remelting region.

[0009] The depth of the valve pit is H = H 气阀下沉量 +H 缸垫厚度 -H 活塞突出量 -(H0+H活塞行程 -H 气阀行程 );

[0010] Wherein: H 气阀下沉量 —Distance from the bottom of the valve to the cylinder head combustion chamber;

[0011] H 缸垫厚度 —Thickness of the cylinder head gasket after installation;

[0012] H 活塞突出量 —The height by which the piston top surface protrudes above the cylinder top surface when the piston is at top dead center;

[0013] H0—The distance between the top surface of the valve and the top dead center of the piston when the valve is closed;

[0014] H 活塞行程 —The displacement of the piston as the crankshaft rotates;

[0015] H 气阀行程 —The displacement of the air valve as the crankshaft rotates;

[0016] Valve recess contour R = R 气阀盘部半径 +3mm.

[0017] Valve recess depth: Its main function is to ensure that there is sufficient clearance between the piston and the valve during operation, so as to prevent the valve and piston from colliding and failing.

[0018] Valve recess outline: Ensure that there is sufficient clearance between the valve recess on the piston and the valve in the vertical direction.

[0019] The thickness of the remelted layer in the upper throat remelting area, W1, is ≥ 2.5 mm; the thickness of the remelted layer in the lower throat remelting area, W2, is ≥ 1.5 mm.

[0020] It also includes a piston insert, which is located on the upper part of the outer wall of the piston to improve the piston's wear resistance.

[0021] The piston ring height H5 > 0.54 * D 缸孔直径 *PCP 发动机爆压 / 14.5; The piston insert thickness H6 > 0.11*D 缸孔直径 *PCP 发动机爆压 / 14.5+0.75.

[0022] It also includes piston cooling oil passages, which are located below the remelting area of ​​the lower throat on the inner wall of the piston to cool the working piston.

[0023] The volume of the piston cooling oil passage is V = 2*((R5+R6)*H7+0.5*π

[0024] *(R5 2 +R6 2 ))*π*H8.

[0025] A process for remelting pistons with upper and lower throats includes the following steps:

[0026] The upper and lower throat remelting areas are shaped using an argon arc welding torch. For the upper throat remelting areas of valve pits with different depths, the argon arc welding torch moves axially to match the corresponding valve pit depth, ensuring that the upper throat remelting area has the same remelted layer thickness W1 around its circumference. The axial displacement S of the argon arc welding torch is obtained through CURVE, which is a curve with the piston rotation angle θ as input. Different axial displacements S of the argon arc welding torch are calibrated at different piston rotation angles θ. When the argon arc welding torch moves axially, the axial displacement S of the argon arc welding torch is obtained according to the piston rotation angle θ at that time. In the above process, the piston rotation speed V is taken as 0.02m / s to 0.04m / s, and the angle between the starting position of the argon arc welding torch, i.e., the straight line formed by the argon arc welding torch and the front and rear ends of the piston, is 37° to 40°.

[0027] The piston of this invention features remelting at both the upper and lower throats, ensuring the strength of both throats and improving the service life of the aluminum piston, thus meeting the requirements of engines with higher explosion pressure and power. For the remelting area of ​​the upper throat at different depths of valve recesses, the argon arc welding torch is moved axially to match the corresponding valve recess depth, ensuring that the remelted layer thickness is the same around the entire circumference of the upper throat remelting area. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the piston of the present invention;

[0029] Figure 2 This is a top view of the piston of the present invention;

[0030] Figure 3 This is a cross-sectional view of the present invention;

[0031] Figure 4 This is a schematic diagram of the piston remelting process control of the present invention;

[0032] Figure 5 This is a control curve diagram of the remelting process of the present invention.

[0033] In the diagram, 100 is the piston, 10 is the upper throat remelting area, 20 is the lower throat remelting area, 30 is the piston insert, 40 is the piston cooling oil passage, 1 is the first exhaust valve pit, 2 is the second exhaust valve pit, 3 is the first intake valve pit, and 4 is the second intake valve pit. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments to facilitate a clear understanding of the present invention, but these descriptions do not constitute a limitation on the present invention.

[0035] like Figure 1 As shown, the present invention includes a piston 100. The upper and lower throats of the combustion chamber region on the inner ring of the piston 100 are provided with an upper throat remelting region 10 and a lower throat remelting region 20 spaced apart. The top of the piston 100 is provided with a plurality of valve pits, which include a plurality of exhaust pits and a plurality of intake pits. The plurality of exhaust pits and the plurality of intake pits are evenly arranged along the center of the piston 100. The upper throat remelting region 10 is located in the inner ring of the plurality of exhaust pits and the plurality of intake pits, and the lower throat remelting region 20 is located below the upper throat remelting region 10.

[0036] Multiple exhaust and intake slots include a first exhaust valve slot 1, a second exhaust valve slot 2, a first intake valve slot 3, and a second intake valve slot 4. The first exhaust valve slot 1, the second exhaust valve slot 2, the first intake valve slot 3, and the second intake valve slot 4 are evenly arranged along the center of the piston 100.

[0037] The thickness W1 of the remelted layer around the upper throat remelting region 10 is a phase.

[0038] Valve pit depth H = H 气阀下沉量 +H 缸垫厚度 -H 活塞突出量 -(H0+H 活塞行程 -H 气阀行程 );

[0039] Wherein: H 气阀下沉量 —Distance from the bottom of the valve to the cylinder head combustion chamber;

[0040] H 缸垫厚度 —Thickness of the cylinder head gasket after installation;

[0041] H 活塞突出量 —The height by which the piston top surface protrudes above the cylinder top surface when the piston is at top dead center;

[0042] H0—The distance between the top surface of the valve and the top dead center of the piston when the valve is closed;

[0043] H 活塞行程 —The displacement of the piston as the crankshaft rotates;

[0044] H 气阀行程 —The displacement of the air valve as the crankshaft rotates.

[0045] The two intake valves have the same stroke, but the intake and exhaust valves have different strokes. Therefore, the depths of the first intake valve recess 3 and the second intake valve recess 4 on the corresponding pistons are the same. Due to the existence of the exhaust braking stroke, the braking and non-braking strokes of the exhaust valves are also different, so the depths of the first exhaust valve recess 1 and the second exhaust valve recess 2 on the pistons are different.

[0046] Valve recess depth: Its main function is to ensure that there is sufficient clearance between the piston and the valve during operation, so as to prevent the valve and piston from colliding and failing.

[0047] In this embodiment, the depth H1 of the first exhaust valve pit 1 is 2.2 mm, the depth H2 of the second exhaust valve pit 2 is 0.6 mm, the depth H3 of the first intake valve pit 3 is 0.8 mm, and the depth H4 of the second intake valve pit 4 is 0.8 mm.

[0048] Valve recess contour R = R 气阀盘部半径 +3mm; ensure sufficient clearance between the valve slot on the piston and the valve in the vertical direction.

[0049] The arc segment R0 is the transition fillet of the valve pit, which is generally 2-3mm to avoid stress concentration at the top of the piston.

[0050] like Figure 2 As shown, in this embodiment, the outline R1 of the first exhaust valve pit 1 is 20mm, the outline R2 of the second exhaust valve pit 2 is 20mm, the outline R3 of the first intake valve pit 3 is 21mm, the outline R4 of the second intake valve pit 4 is 21mm, and the arc segment R0 is 2.2mm.

[0051] like Figure 2 As shown, in this embodiment, the displacement X1 of the center of the first exhaust valve pit 1 from the center of the piston 100 is 1mm, and Y1 is 34.8mm; the displacement X2 of the center of the second exhaust valve pit 2 from the center of the piston 100 is 33.7mm, and Y2 is 8.5mm; the displacement X3 of the center of the first intake valve pit 3 from the center of the piston 100 is 2.2mm, and Y3 is 34.1mm; and the displacement X4 of the center of the second intake valve pit 4 from the center of the piston 100 is 33.8mm, and Y4 is 4.1mm.

[0052] Valve recess center position X / Y: Ensure that the position of the piston valve recess matches the position of the valve on the engine cylinder head, and the valve recess center position X / Y is the same as the valve center position.

[0053] It also includes a piston insert 30, which is located on the upper part of the outer wall of the piston 100.

[0054] Piston ring height H5 > 0.54 * D (30mm) 缸孔直径 *PCP 发动机爆压 / 14.5;

[0055] Piston inlay 30mm thick, H6 > 0.11*D 缸孔直径 *PCP 发动机爆压 / 14.5+0.75.

[0056] It also includes a piston cooling oil passage 40, which is located below the remelting area 20 of the lower throat on the inner wall of the piston 100.

[0057] Piston cooling oil passage 40 is used for piston cooling during piston operation.

[0058] Piston cooling oil passage volume V = 2*((R5+R6)*H7+0.5*π*(R5) 2 +R6 2 ))*π*H8.

[0059] Through the aforementioned remelting process in the upper throat region, the remelted layer thickness W1 in the upper throat remelting region 10 can be ≥ 2.5 mm. Since the upper throat region of the piston is the area subjected to the most severe thermal and mechanical loads during piston operation, if the remelted layer thickness here is less than 2.5 mm, the piston cannot meet the high temperature and high explosion pressure conditions of the engine, leading to throat cracking failure (which has already occurred in engine testing). The remelted layer thickness W2 in the lower throat remelting region 20 is ≥ 1.5 mm.

[0060] like Figure 3 As shown, in this embodiment, the thickness W1 of the upper throat remelting area 10 is 2.5 mm, the thickness W2 of the lower throat remelting area 20 is 1.5 mm, the height H5 of the piston insert 30 is 8.5 mm, and the thickness H6 is 2.55 mm; the upper arc R5 of the piston cooling oil passage 40 is 3.7 mm, the lower arc R6 is 4.65 mm, the height H7 is 5.65 mm, and the center distance H8 is 39.15 mm.

[0061] In the case of valve pits of varying depths in the upper throat region of the piston, the traditional piston remelting process (without axial movement of the argon arc welding torch) cannot guarantee a consistent remelting thickness around the 10 circumferences of the upper throat remelting area. At the valve pit with the greatest depth, the remelting thickness cannot meet the requirements, resulting in the weakest piston strength at this location, leading to piston failure during operation.

[0062] The remelting process of the piston upper throat region of the present invention is shown in Figure 4. The starting position of the argon arc welding torch is as follows: Figure 4 As shown, the angle between the argon arc welding torch and the straight line formed by the front and rear ends of the piston is 37° to 40°. As the piston 100 rotates, the direction of rotation is shown in the diagram. Figure 4 In this embodiment, the rotational speed V of piston 100 is taken as 0.03 m / s, and the displacement S of the argon arc welding torch is as follows: Figure 5 For the upper throat remelting area 10 of the valve pit at different depths, the argon arc welding torch is moved axially to match the corresponding valve pit depth, ensuring that the upper throat remelting area 10 has the same remelted layer thickness W1 around its circumference.

[0063] The piston rotation angle θ is the angle of the piston's own rotation, the rotational speed V is the piston's own rotational speed, and the axial displacement S of the TIG welding torch refers to the displacement of the TIG welding torch along the axial direction of the piston. See Table 1 for details. Figure 5 The CURVE curve in the middle.

[0064] Table 1. Axial displacement S of TIG welding torch / Piston rotation angle θ

[0065]

[0066]

[0067] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A process for remelting pistons at the upper and lower throats, characterized in that: The piston (100) has an upper throat remelting area (10) and a lower throat remelting area (20) spaced apart at the upper and lower throats of the combustion chamber region on the inner ring of the piston (100). The piston (100) has a plurality of valve pits on the top, which include a plurality of exhaust pits and a plurality of intake pits. The upper throat remelting area (10) is located at the inner ring of the plurality of exhaust pits and the plurality of intake pits. The lower throat remelting area (20) is located below the upper throat remelting area (10). The upper throat remelting region (10) has the same remelting layer thickness W1 around its perimeter; The process for remelting the upper and lower throat piston includes the following steps: The upper throat remelting area (10) and lower throat remelting area (20) are processed and shaped using an argon arc welding torch. For the upper throat remelting area (10) with different depths of valve pits, the argon arc welding torch is moved axially to match the corresponding valve pit depth, ensuring that the upper throat remelting area (10) has the same remelting layer thickness W1 around. The value of the axial displacement S of the argon arc welding torch is obtained through CURVE. CURVE is a curve with the piston rotation angle θ as input. Different axial displacements S of the argon arc welding torch are calibrated under different piston rotation angles θ. When the argon arc welding torch moves axially, the axial displacement S of the argon arc welding torch is obtained according to the piston rotation angle θ at that time. In the above process, the piston rotation speed V is taken as 0.02m / s~0.04m / s. The angle between the starting position of the argon arc welding torch, that is, the straight line formed by the argon arc welding torch and the front end and rear end of the piston, is 37°~40°.

2. The process for remelting the upper and lower throat piston according to claim 1, characterized in that: The plurality of exhaust pits and plurality of intake pits include a first exhaust valve pit (1), a second exhaust valve pit (2), a first intake valve pit (3), and a second intake valve pit (4).

3. The process for remelting the upper and lower throat piston according to claim 1, characterized in that: The depth of the valve pit is H=H 气阀下沉量 +H 缸垫厚度 -H 活塞突出量 -(H0+H 活塞行程 -H 气阀行程 ); Wherein: H 气阀下沉量 —Distance from the bottom of the valve to the cylinder head combustion chamber; H 缸垫厚度 —Thickness of the cylinder head gasket after installation; H 活塞突出量 —The height by which the piston top surface protrudes above the cylinder top surface when the piston is at top dead center; H0—The distance between the top surface of the valve and the top dead center of the piston when the valve is closed; H 活塞行程 —The displacement of the piston as the crankshaft rotates; H 气阀行程 —The displacement of the air valve as the crankshaft rotates; Valve recess contour R=R 气阀盘部半径 +3mm.

4. The process for remelting the upper and lower throat piston according to claim 2, characterized in that: The thickness of the remelted layer in the upper throat remelting region (10) is W1≥2.5mm; the thickness of the remelted layer in the lower throat remelting region (20) is W2≥1.5mm.

5. The process for remelting the upper and lower throat piston according to claim 1, characterized in that: It also includes a piston insert (30), which is located on the upper part of the outer wall of the piston (100).

6. The process for remelting the upper and lower throat piston according to claim 5, characterized in that: The piston ring (30) has a height H5 > 0.54 * D. 缸孔直径 *PCP 发动机爆压 / 14.5; The piston insert (30) thickness H6 > 0.11*D 缸孔直径 *PCP 发动机爆压 / 14.5+0.

75.

7. The process for remelting the upper and lower throat piston according to claim 1, characterized in that: It also includes a piston cooling oil passage (40), which is located below the remelting area (20) of the lower throat on the inner wall of the piston (100).

8. The process for remelting the upper and lower throat piston according to claim 7, characterized in that: The volume of the piston cooling oil passage (40) is V = 2*((R5+R6)*H7+0.5*π*(R5) 2 +R6 2 ))*π*H8; where R5 is the upper arc radius of the piston cooling oil passage (40), R6 is the lower arc radius of the piston cooling oil passage (40), H7 is the height of the piston cooling oil passage (40), and H8 is the center distance of the piston cooling oil passage (40).

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