High-strength aluminum alloy integrated exhaust cylinder head and its tilting casting process

Abstract

A high-strength aluminum alloy integrated exhaust cylinder head and its tilting casting process include a riser at the top of the cylinder head body and above the spark plug mounting hole. An internal riser connects the riser to the bolt column and tappet platform in sequence below the riser. A diverter port is provided at the feed opening of the riser, corresponding to the upper portion of the internal riser. During the initial 90-degree tilting process, the molten aluminum smoothly enters the integrated exhaust chamber of the metal mold at a relatively low height, ensuring that the oxide film at the leading edge of the molten aluminum does not rupture, reducing the risk of slag inclusions and pores in the blank, and facilitating sequential solidification from the bottom combustion chamber of the casting to the top of the spark plug mounting hole. This invention improves the overall performance of the cylinder head, including tensile strength, yield strength, and elongation. This casting process is at the forefront in terms of quality, production efficiency, and mechanical properties of the castings, meeting the overall requirements of high quality, high efficiency, and high performance.

Description

Technical Field

[0001] The present invention relates to the field of automobile engines, in particular to an aluminum alloy cylinder head and a casting and pouring molding process thereof. Background Art

[0002] Currently, the aluminum alloy integrated exhaust cylinder head has a profile of 512mm × 314mm × 141mm. The water channel core structure is complex and elongated, with a narrow, thin wall between the water channel and the exhaust channel. These challenges pose technical challenges to core manufacturing and casting processes. The disadvantages of using a metal mold gravity bottom pouring casting process include: feeding the material from the bottom of the casting (the combustion chamber), which hinders the sequential solidification from the bottom to the top (the riser), requiring an increase in the riser volume, which reduces the process yield by approximately 12%. Feeding the material from the bottom of the casting results in excessively high temperatures, slowing the solidification rate and making it difficult to meet the product's mechanical properties and combustion chamber SDAS requirements. The runners make the metal mold bulky and prone to aluminum leakage during casting, resulting in high production and maintenance costs, long curing times, and low production efficiency. Casting defects such as slag holes and post-processing exposure are also common, and casting waste is generally controlled within 5%. The disadvantage of using a metal mold gravity top-pouring casting process is that the aluminum liquid inlet is located at the top cover edge of the casting. When filling the metal mold cavity, the aluminum liquid flows unsteadily due to the large drop, causing splashing, sand washing, and air entanglement, which can easily cause aluminum liquid oxidation, forming secondary oxidation slag inclusions inside the casting, oxidation flow marks on the lower surface of the casting corresponding to the gate, and large air holes around the gate. The quality of castings using this casting process is difficult to control. The disadvantages of using a metal mold low-pressure casting process are: the inlet gate is generally set around the combustion chamber at the bottom of the casting, so the solidification rate is very slow, making it difficult to meet the product's mechanical properties and the combustion chamber's SDAS requirements; the molding water channel cavity is prone to sand adhesion and difficult to clean under low pressure; the gas emitted by the sand core after being heated in the closed mold cavity is not easy to discharge, causing air holes inside the casting; the wall thickness at the junction of the spark plug mounting hole and the oil plate deteriorates significantly, and is far away from the pouring gate at the bottom of the casting, so the casting stress is large during solidification, and cracks often appear after heat treatment. Therefore, it is difficult to control the quality of the cylinder head with this casting process. Summary of the Invention

[0003] In response to the shortcomings of the existing technology, the present invention provides a high-strength aluminum alloy integrated exhaust cylinder head and its tilting casting pouring process, which has a simple structure and a simple process. It uses a tilting method to allow the molten aluminum to enter the metal mold cavity smoothly at a low position, avoiding the risks of secondary oxidation slag inclusions and air holes; feeding from the riser on the top of the cylinder head is conducive to the solidification of the casting from bottom to top.

[0004] In order to achieve the above-mentioned purpose, the present invention is implemented through the following technical solution: a high-strength aluminum alloy integrated exhaust cylinder head, including a cylinder head body, a camshaft mounting hole and a tappet platform, a spark plug mounting hole, a fuel nozzle mounting hole, and a combustion chamber, wherein intake and exhaust passages, upper and lower water jackets, and oil passages are provided in the cylinder head body, a riser is provided at the top of the cylinder head body and on the spark plug mounting hole, and an internal riser is connected to the bolt column and the tappet platform in sequence under the riser, and a diverter port is provided at the feed port of the riser and corresponding to the upper part of the internal riser.

[0005] Water cooling inserts are arranged at the sides of the intake and exhaust passages of the cylinder head body. Clamping platforms are arranged on both sides of the riser, and a riser minimum height scale line is arranged on the top of the riser.

[0006] The tilting casting pouring molding process adopted by the high-strength aluminum alloy integrated exhaust cylinder head is as follows: before the 90-degree tilt feeding, the top of the metal mold and the feed port of the riser corresponding to the top of the cylinder head casting are docked with the pouring cup, and the aluminum liquid level in the pouring cup is at the root of the riser; during the initial 90-degree tilting process, the aluminum liquid enters the integrated exhaust cavity of the metal mold smoothly at a lower height to ensure that the oxide film at the front of the aluminum liquid will not break, reduce the risk of slag inclusion and air holes in the blank, and reduce the scrap rate of the casting blank, and set a diversion port at the feed port of the riser to prevent the liquid surface oxide film of the pouring cup from entering the metal mold cavity in advance and floating on the top of the riser; the internal riser under the riser is connected to the bolt column and the push rod platform to prevent it from shrinking and at the same time compensate for the shrinkage of the surrounding push rod platforms; a water-cooling insert is provided in the exhaust feed module of the metal mold at the side of the intake and exhaust passage corresponding to the cylinder head body.

[0007] During the design stage of the cylinder head body, the wall thickness of the exhaust side cover is ensured to be 4.5-5.5mm, and the wall thickness of the exhaust side cover is allowed to have a positive deviation during casting; during the design stage of the cylinder head body, the wall thickness of the intake side cover is ensured to be 5.0-5.5mm, and the wall thickness of the intake side cover is allowed to have a positive deviation during casting.

[0008] After adopting the present invention, feeding from the riser of the cylinder head is conducive to the sequential solidification forming from the bottom combustion chamber of the casting to the top of the spark plug mounting hole. The internal riser connection bolt column and the push rod platform are set to effectively compensate for shrinkage, ensuring that the product performance meets the requirements. The present invention is provided with a water-cooled insert in the exhaust feed module. For the continuous production of 17kg blanks in batches, the solidification time is 250S, which can achieve long-term stable production, reflecting the breakthrough of large castings to achieve high-efficiency production. The comprehensive casting scrap rate is controlled within 2.3%. Due to the implementation of National VI, the performance requirements of the cylinder head are improved. Its tensile strength is 280Mpa, yield strength is 220Mpa, elongation is ≥4%, and combustion chamber SDAS (secondary dendrite spacing) is ≤25um; it is more than 15% higher than the original overall performance requirements. This casting process is at the leading level in the field of aluminum alloy integrated exhaust cylinder head casting in terms of quality level, production efficiency, and mechanical properties of castings, and meets the overall requirements of high quality, high efficiency, and high performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0010] Figure 1 This is a schematic structural diagram of the high-strength aluminum alloy integrated exhaust cylinder head of the present invention.

[0011] Figure 2 This is a structural diagram of the cylinder head body and the pouring cup of the present invention (before 90-degree tilting).

[0012] Figure 3 This is a structural diagram of the cylinder head body and the pouring cup of the present invention (after being tilted 90 degrees).

[0013] Figure 4 It is a schematic structural diagram of the present invention (in the riser feeding state, local cross section).

[0014] Figure 5 This is a schematic structural diagram (side view) of the present invention connected to a water-cooled insert. DETAILED DESCRIPTION

[0015] like Figures 1 to 4As shown, the high-strength aluminum alloy integrated exhaust cylinder head of the present invention includes a cylinder head body 1, a (double overhead) camshaft mounting hole 15 and a tappet platform 16 (located in the middle of the cylinder head body), a (straight row) spark plug mounting hole 18 (located in the upper part of the cylinder head body), a (direct injection) nozzle mounting hole 22, and a combustion chamber 13 (located at the bottom of the cylinder head body). Intake and exhaust passages 14, upper and lower water jackets 21, (double row high pressure) oil passages 20 (and tappets) are provided in the cylinder head body 1. A riser 2 is provided at the top of the cylinder head body 1 and on the spark plug mounting hole 18. Under the riser 2, it is connected to the bolt column 17 (boss-shaped) and the tappet platform 16 in sequence through an internal riser 10. A diverter port 19 is provided at the feed port 9 of the riser 2 (for docking with the pouring cup 5) and corresponding to the upper part of the internal riser.

[0016] like Figure 5 As shown, a water-cooled insert 12 (connected to a water cooler) is provided at the side of the intake and exhaust passages 14 of the cylinder head body 1 (corresponding to the exhaust feed module 23 of the metal mold used in the casting process). Figure 1 As shown, clamping platforms 4 are installed on both sides of the riser 2 for grabbing the workpiece (cylinder head casting) for intelligent automatic pouring. A riser minimum height scale line 3 is provided on the top of the riser 2 to realize intelligent control of the amount of automatic aluminum scooping.

[0017] The 90-degree tilt casting process used in the high-strength aluminum alloy integrated exhaust cylinder head is as follows: the aluminum alloy liquid is introduced into the pouring cup 5 of the metal mold for forming the aluminum alloy cylinder head, and the pouring cup is arranged above the exhaust side of the metal mold. Figure 2 、 Figure 3 As shown, before the 90-degree tilting feeding, the top of the metal mold and the feed port 9 of the riser 2 corresponding to the top of the cylinder head casting are docked with the pouring cup 5, and the aluminum liquid level in the pouring cup 5 is at the root of the riser 2; when the 90-degree tilting process begins (the tilting angle is from 0 degrees to 90 degrees), the aluminum liquid smoothly enters the integrated exhaust cavity 7 of the metal mold at a lower height (i.e., the drop is smaller), ensuring that the oxide film at the front edge 6 of the aluminum liquid will not break, reducing the risk of slag inclusion and air holes in the blank, and reducing the scrap rate of the casting blank.

[0018] like Figure 2 、 Figure 3 、 Figure 4As shown, a shut-off port 19 (with a width of 20-25 mm, with a width of 23 mm being preferred) is provided at the feed port 9 of the riser 2 to prevent the liquid surface oxide film of the pouring cup 5 from prematurely entering the metal mold cavity and floating on the top of the riser. In order to prevent shrinkage in the thermal joint of the integrated exhaust flange of the cylinder head, the wall thickness of the exhaust side cover 8 is ensured to be 4.5-5.5 mm (with a wall thickness of 5.0 mm being preferred) during the design phase of the cylinder head body 1, and the wall thickness of the exhaust side cover is allowed to have a positive deviation during casting; the internal riser 10 under the riser 2 connects the bolt column (φ25×28 mm) and the tappet platform to prevent shrinkage and compensate for shrinkage of the surrounding tappet platforms; in order to prevent shrinkage in the high-pressure oil passage of the cylinder head and its tappets during thermal joints, the wall thickness of the intake side cover 11 is ensured to be 5.0-5.5 mm (with a wall thickness of 5.0 mm being preferred) during the design phase of the cylinder head body 1, and the wall thickness of the intake side cover is allowed to have a positive deviation during casting. As shown Figure 5 As shown, a water-cooled insert 12 is installed within the exhaust and feed module 23 of the metal mold (corresponding to the side of the cylinder head body's intake and exhaust ducts). The riser width is limited to 23mm to ensure the temperature remains below 450°C when the mold is opened. This allows for continuous batch production of 17kg cylinder head blanks, with a curing time of 250 seconds, ensuring long-term stable production and demonstrating the high-efficiency production advantage of large castings.

[0019] The advantages of the casting pouring molding process of the present invention are: feeding from the riser of the cylinder head is more conducive to setting up a separate water cooling mechanism from the combustion chamber at the bottom of the cylinder head (casting), accelerating the solidification rate, and forming in a layer-by-layer sequential solidification manner from the bottom combustion chamber to the spark plug mounting hole and the top of the riser, ensuring that the product performance can meet the relevant high requirements.

Claims

1. High-strength aluminum alloy integrated exhaust cylinder head, including cylinder head body, camshaft mounting hole and tappet platform, spark plug mounting hole, fuel nozzle mounting hole, combustion chamber, and intake and exhaust ducts, upper and lower water jackets, and oil ducts are provided in the cylinder head body. The characteristics are: A riser is provided on the top of the cylinder head body and on the spark plug mounting hole, and the riser is connected to the bolt column and the tappet platform in sequence through the internal riser. A diverter port is provided at the feed port of the riser and corresponding to the upper part of the internal riser; water-cooling inserts are provided on the sides of the intake and exhaust passages of the cylinder head body, clamping platforms are installed on the outer sides of the riser, and a riser minimum height scale line is provided on the top of the riser; the tilting casting molding process adopted is: before the feeding is tilted 90 degrees, the top of the metal mold and the feed port of the riser corresponding to the top of the cylinder head casting are docked with the pouring cup, and the aluminum liquid level in the pouring cup is at the root of the riser; during the initial 90-degree tilting process, the aluminum liquid enters the integrated exhaust cavity of the metal mold smoothly at a lower height to ensure that the aluminum liquid The oxide film at the front will not break, reducing the risk of slag inclusion and air holes in the blank and the scrap rate of the casting blank. A diverter port is set at the feed port of the riser to prevent the liquid surface oxide film of the pouring cup from entering the metal mold cavity in advance and floating on the top of the riser; the internal riser under the riser connects the bolt column and the push rod platform to prevent it from shrinking and at the same time compensates the shrinkage of the surrounding push rod platforms; water-cooling inserts are set in the exhaust feed module of the metal mold and on the side of the intake and exhaust duct corresponding to the cylinder head body; in the design stage of the cylinder head body, the wall thickness of the exhaust side cover is ensured to be 4.5-5.5mm, and the wall thickness of the exhaust side cover is positive during casting. The wall thickness of the intake side cover is ensured to be 5.0-5.5mm, and the wall thickness of the intake side cover is positive during casting.

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