A frustum-shaped chill for use in sand casting of cylinder head firing surfaces

Abstract

This invention discloses a frustum-shaped chill for the firing surface of cylinder heads in sand casting, belonging to the technical field of casting process auxiliary parts. The chill includes a chill body with multiple circular bosses evenly distributed along the radial direction on its top surface for precise positioning within the sand mold. The top surface of the body has crisscrossing venting grooves to expel gases generated during the solidification of the sand core and molten metal. The body is divided into upper and lower frustum sections, with the upper frustum being higher than the lower frustum, forming a gradient cooling structure. Through structural optimization, this invention achieves precise and controllable cooling of the cylinder head firing surface, reducing defects such as shrinkage porosity, looseness, and gas porosity to near zero, improving casting density and yield, and is suitable for sand casting production of various aluminum engine cylinder heads.

Description

Technical Field

[0001] This invention relates to the field of auxiliary components for sand casting processes, and in particular to a frustum-shaped chill for the fire-generating surface of a cylinder head in sand casting. Background Technology

[0002] The cylinder head is a major component of an engine, a complex spatial structure characterized by high load-bearing capacity, irregular shape, significant variations in wall thickness, and asymmetrical structure. The solidification process of cylinder head castings is not conducive to sequential solidification, easily leading to defects such as shrinkage cavities and porosity within the casting, severely impacting its performance and quality, and even causing it to be scrapped. To achieve sequential solidification, simultaneous solidification of localized hot spots, and control of segregation, chills are placed in the thicker parts of the casting to avoid these casting defects. Currently, cylinder head castings often use chills made of low-carbon steel, which provide a gentle cooling effect. However, especially for complex castings like cylinder heads, it is difficult to avoid casting defects such as shrinkage cavities and porosity.

[0003] This invention aims to specifically address three core technical bottlenecks in the application of chills on the fire-heating surface of sand-cast cylinder heads, specifically manifested in:

[0004] Insufficient cooling efficiency: There is a gap at the interface between the chill and the sand mold, which reduces the heat exchange efficiency and fails to meet the rapid solidification requirements of the key areas of the fire face.

[0005] Positioning accuracy deviation: The spatial position of the chill in the sand mold is prone to displacement, resulting in uneven distribution of local chilling intensity and affecting the uniformity of the casting structure.

[0006] Venting system defects: During the pouring process, the gas around the chill cannot be effectively discharged, which can easily lead to casting defects such as porosity and shrinkage, reducing the product qualification rate.

[0007] The aforementioned problems directly restrict the forming quality and production stability of cylinder head castings, requiring a systematic solution through structural innovation. Therefore, it is urgent to develop a special chill with strong structural adaptability, controllable chilling effect, and exhaust function to solve the casting defects of the cylinder head firing surface. Summary of the Invention

[0008] The purpose of this invention is to provide a frustum-shaped chill for the firing surface of a cylinder head in sand casting. Through structural optimization, it achieves precise chilling, efficient exhaust and stable positioning, and solves casting defects such as shrinkage porosity and gas holes in the firing surface of the cylinder head.

[0009] To achieve the above objectives, the present invention provides a frustum-shaped chill for the fire-heating surface of a cylinder head in sand casting, comprising: a chill body including a circular boss, an upper frustum, and a lower frustum integrally formed from top to bottom; the top surface of the upper frustum is circular, and the cross-section is an inverted trapezoid with a wider top and narrower bottom; the circular boss protrudes from the top surface of the upper frustum and is concentrically arranged with the upper frustum; there are multiple circular bosses, which are evenly arranged along the radial direction of the top surface of the upper frustum; the top surface of the lower frustum is connected to the bottom surface of the upper frustum, and the cross-section of the lower frustum is a trapezoid with a narrower top and wider bottom; wherein, the height of the upper frustum is greater than the height of the lower frustum; the top surface of the chill body is provided with a crisscrossing, through-type grid exhaust groove structure, the grid being formed by the intersection and enclosing of horizontal and vertical grooves to form a regular grid layout, which is distributed in accordance with the outline of the top surface of the chill; the outer diameter of the circular boss is set to be smaller than the inner diameter of the corresponding sand mold hole, forming a clearance fit positioning structure; the top surface diameter of the chill body is adapted to the area occupied by the sand mold hole group in the sand mold.

[0010] According to the embodiments of this application, the total height of the chill body is 20-30mm, the height of the upper truncated cone is 12-18mm, and the height of the lower truncated cone is 8-12mm.

[0011] According to embodiments of this application, the chill body is made of low-carbon steel or copper.

[0012] According to an embodiment of this application, the exhaust groove adopts a refined narrow groove design, with the width of a single exhaust groove controlled at 0.8 to 1.2 mm and the groove depth set at 1 to 1.2 mm.

[0013] According to an embodiment of this application, the chill body is designed as a waist-shaped frustum cone, and its contact surface with the sand mold is a waist-shaped inclined surface structure.

[0014] According to an embodiment of this application, after the truncated cone-shaped chill is de-rusted by sandblasting to remove the oxide scale, it is coated with a high-temperature resistant coating to prevent the chill from sticking to the casting.

[0015] According to an embodiment of this application, the circular boss has a diameter of 5-8 mm, and there are 4-6 of them, which are evenly distributed along the radial direction of the top surface of the upper frustum.

[0016] According to an embodiment of this application, the upper end of the circular boss protrudes 2mm beyond the top surface of the upper frustum.

[0017] According to an embodiment of this application, the cross-section of the circular boss is a standard circular structure.

[0018] According to an embodiment of this application, the exhaust groove is located on the top surface of the circular boss.

[0019] The advantages of the present invention over the prior art are:

[0020] The waist-shaped, frustum-shaped chill used for the fire-facing surface of the sand-cast cylinder head achieves multiple technological advantages through structural innovation, specifically manifested in:

[0021] 1. Waist-shaped sloping surface structure improves heat exchange efficiency and sand mold quality: The chill adopts a waist-shaped frustum-shaped design, and its contact surface with the sand mold is a waist-shaped sloping surface structure. This design allows the sand to quickly and firmly fill the area around the chill, ensuring the quality of sand mold forming on the one hand, and improving heat exchange efficiency by increasing the effective contact area on the other hand, significantly improving the cooling speed during pouring, and ensuring the casting quality of the cylinder head fire face.

[0022] 2. Cross-venting groove design reduces porosity defects: The venting grooves set on the top surface of the chill can effectively discharge the gas generated during the solidification process of the molten metal and the sand core, avoiding the accumulation of gas inside the casting and forming porosity, thereby improving the casting quality.

[0023] 3. Precise positioning via waist-shaped side: The waist-shaped structure of the chill side is designed to match the sand mold hole, which can precisely fix the chill in the sand mold, avoiding uneven local cooling caused by chill displacement during the pouring process, and further ensuring the casting forming accuracy. Attached Figure Description

[0024] Figure 1 This is a three-dimensional structural schematic diagram of a frustum-shaped chill for the fire-generating surface of a cylinder head in sand casting, as an example of the present invention.

[0025] Figure 2 for Figure 1 A side view diagram;

[0026] Figure 3 for Figure 1 Top view.

[0027] The annotations in the attached figures are explained as follows:

[0028] 10. Upper cone, 11. Circular boss, 12. Exhaust groove, 20. Lower cone. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0030] Please see Figure 1 , Figure 2 and Figure 3As shown in the example, this application provides a frustum-shaped chill for sand casting cylinder head firing surfaces. The chill includes a waist-shaped frustum-shaped body with multiple circular protrusions 11 evenly distributed along the radial direction on the top surface for precise positioning within the sand mold. The top surface of the body has crisscrossing venting grooves 12 to expel gases generated during the solidification of the sand core and molten metal. The body is divided into upper and lower frustum sections, with the upper frustum being taller than the lower frustum, forming a gradient cooling structure. This invention, through structural optimization, achieves precise and controllable cooling of the cylinder head firing surface, reducing defects such as shrinkage porosity, looseness, and gas porosity to near zero, improving casting density and yield, and is suitable for sand casting production of various aluminum engine cylinder heads.

[0031] In this embodiment, a frustum-shaped chill for the fire-heating surface of a cylinder head made by sand casting includes a chill body, comprising a circular boss 11, an upper frustum 10, and a lower frustum 20 integrally formed from top to bottom.

[0032] In this embodiment, the top surface of the upper cone 10 is circular, and the cross-section is an inverted trapezoid that is wider at the top and narrower at the bottom.

[0033] Specifically, a circular boss 11 protrudes from the top surface of the upper truncated cone 10 and is concentrically arranged with the upper truncated cone 10. There are multiple circular bosses 11, which are evenly arranged along the radial direction of the top surface of the upper truncated cone 10. The upper end of the circular boss 11 extends out of the top surface of the upper truncated cone 10, and the lower end is integrally connected to the top surface of the upper truncated cone 10.

[0034] Specifically, the circular boss 11 has a standard circular cross-section.

[0035] Specifically, a circular boss 11 is provided on the upper part of the chill to enhance the positioning stability with the sand mold. The boss has a diameter of 5-8 mm and a quantity of 4-6, which are evenly distributed along the radial direction.

[0036] Specifically, the outer diameter of the circular boss 11 is set smaller than the inner diameter of the corresponding sand mold hole, forming a clearance fit positioning structure. The top surface diameter of the chill body is adapted to the area occupied by the sand mold hole group in the sand mold. It can be understood that setting the outer diameter of the circular boss 11 to be smaller than the inner diameter of the corresponding sand mold hole, forming a clearance fit positioning structure, enables rapid pre-assembly and precise alignment of the chill, effectively avoiding boss compression and cracking of the sand mold hole wall during assembly, and preventing sand holes and sand inclusion defects in the casting. A small annular venting gap is formed between the boss and the sand mold hole, allowing residual gas in the cavity and gas released from the heated sand core to be easily discharged, eliminating the risk of air pockets and trapped air in the boss contact area, and preventing local porosity and looseness defects on the cylinder head firing surface.

[0037] Specifically, 16 circular bosses 11 can be uniformly arranged on the top surface of the chill body along the radial direction. The cross-section of the circular boss 11 is circular with a diameter of 3mm, which is smaller than the 5mm diameter of the corresponding sand mold hole. The upper end of the circular boss 11 extends 2mm out of the top surface of the truncated cone-shaped body, and the lower end is integrally formed with the top surface of the truncated cone-shaped body. It is used to position the chill in the sand mold and prevent the chill from shifting during the casting process.

[0038] In this embodiment, the top surface of the lower frustum 20 is connected to the bottom surface of the upper frustum 10, and the cross-section of the lower frustum 20 is a trapezoid that is narrower at the top and wider at the bottom.

[0039] Specifically, the upper inverted trapezoidal truncated cone and the lower trapezoidal truncated cone are integrally formed, and the side of the chill body is a waist-shaped structure. The waist-shaped structure on the side of the chill is matched with the sand mold hole, which can accurately fix the chill in the sand mold, avoid the problem of uneven local cooling caused by the displacement of the chill during the pouring process, and further ensure the casting forming accuracy.

[0040] Specifically, the chill body is designed as a waist-shaped frustum, and its contact surface with the sand mold is a waist-shaped inclined surface structure.

[0041] Specifically, the height of the upper frustum 10 is greater than the height of the lower frustum 20. Preferably, the height of the upper frustum 10 is 20mm and the height of the lower frustum 20 is 10mm, forming a gradient frustum structure, optimizing the cooling gradient, guiding the casting to solidify sequentially, and improving the feeding effect.

[0042] In this embodiment, the top surface of the chill body is provided with a crisscrossing, interconnected grid venting channel structure. The grid is formed by the intersection and encirclement of horizontal and vertical channels, creating a regular mesh layout that conforms to the overall contour of the chill's top surface. The venting channels on the top surface of the chill can effectively discharge gases generated during the solidification process of the molten metal and the sand core, preventing gas from accumulating inside the casting and forming pores, thereby improving the casting quality.

[0043] Specifically, the total height of the chill body is 20-30mm, the height of the upper truncated cone 10 is 12-18mm, and the height of the lower truncated cone 20 is 8-12mm.

[0044] Specifically, the chill body is made of low-carbon steel or copper. Low-carbon steel is the preferred material for general cylinder head applications due to its low cost and moderate chilling effect; while copper components have a significantly higher thermal conductivity than low-carbon steel, resulting in stronger chilling capabilities, making them suitable for thicker parts of the cylinder head or high-end applications with stringent solidification quality requirements.

[0045] Specifically, the venting groove 12 is located on the top surface of the circular boss 11. The venting groove 12 adopts a refined narrow groove design. The width of a single venting groove is controlled at 0.8 to 1.2 mm, and the groove depth is set at 1 to 1.2 mm. The groove is narrow and shallow, which can form a continuous and unobstructed venting channel, and prevent aluminum liquid from seeping into the groove and sticking sand and slag, thus avoiding the chill and casting from getting stuck during welding.

[0046] Specifically, after the truncated cone-shaped chills are sandblasted to remove rust and scale, they are coated with a high-temperature resistant coating to prevent them from sticking to the castings.

[0047] In this embodiment, the workflow of a frustum-shaped chill for the firing surface of a cylinder head in sand casting is as follows: ① Sand mold preparation stage: The chill achieves precise matching with the sand mold through the waist-shaped side and the circular boss 11 structure, ensuring stable fixation at the preset position of the firing surface of the cylinder head; ② Pouring and solidification stage: After the molten metal comes into contact with the chill, the waist-shaped inclined surface design significantly increases the heat exchange area and accelerates the local solidification process, thereby achieving sequential solidification control of the casting; ③ Gas discharge stage: The gas generated during solidification is efficiently discharged through the cross exhaust grooves 12 on the surface of the chill, effectively avoiding the formation of porosity defects; ④ Separation and reuse stage: After the casting is formed, the chill naturally separates from the casting and can be reused in the production cycle after cleaning.

[0048] In this embodiment, the working principle of a frustum-shaped chill for the fire-facing surface of a cylinder head in sand casting is as follows: During the sand casting of the cylinder head, this chill is pre-embedded in the corresponding position of the fire-facing surface of the cylinder head in the sand mold cavity, and precise positioning is achieved through the cooperation of the circular boss 11 and the sand mold hole; after the molten metal is poured, the frustum-shaped body locally chills the fire-facing surface of the cylinder head, and the gradient frustum structure guides the casting to solidify sequentially from bottom to top, eliminating shrinkage defects; at the same time, the gas generated by the solidification of the sand core and the molten metal is quickly discharged through the exhaust groove 12 on the top surface to avoid porosity defects; the waist-shaped frustum structure of the chill perfectly matches the irregular hot spot of the fire-facing surface, achieving precise control of the chilling range, avoiding casting cracks caused by excessive chilling, and finally producing a high-quality cylinder head casting with near-zero shrinkage, porosity, and other defects and high dimensional accuracy.

[0049] In summary, the technical solution of this application has the following beneficial effects:

[0050] 1. Waist-shaped sloping surface structure improves heat exchange efficiency and sand mold quality: The chill adopts a waist-shaped frustum-shaped design, and its contact surface with the sand mold is a waist-shaped sloping surface structure. This design allows the sand to quickly and firmly fill the area around the chill, ensuring the quality of sand mold forming on the one hand, and improving heat exchange efficiency by increasing the effective contact area on the other hand, significantly improving the cooling speed during pouring, and ensuring the casting quality of the cylinder head fire face.

[0051] 2. Cross-venting groove design reduces porosity defects: The venting grooves set on the top surface of the chill can effectively discharge the gas generated during the solidification process of the molten metal and the sand core, avoiding the accumulation of gas inside the casting and forming porosity, thereby improving the casting quality.

[0052] 3. Precise positioning via waist-shaped side: The waist-shaped structure of the chill side is designed to match the sand mold hole, which can precisely fix the chill in the sand mold, avoiding uneven local cooling caused by chill displacement during the pouring process, and further ensuring the casting forming accuracy.

[0053] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A conical frustum shaped chills for sand cast cylinder head fire deck, characterized by, include: The chilled iron body includes a circular boss, an upper cone, and a lower cone, all integrally formed from top to bottom. The top surface of the upper frustum is circular, and the cross-section is an inverted trapezoid that is wider at the top and narrower at the bottom; The circular protrusion protrudes from the top surface of the upper cone and is concentrically arranged with the upper cone. There are multiple circular protrusions, which are evenly arranged along the radial direction of the top surface of the upper cone. The top surface of the lower truncated cone is connected to the bottom surface of the upper truncated cone, and the cross-section of the lower truncated cone is a trapezoid that is narrower at the top and wider at the bottom. The height of the upper cone is greater than the height of the lower cone; The top surface of the chilled iron body is provided with a crisscrossing grid exhaust groove structure. The grid is formed by the intersection and encirclement of horizontal and vertical grooves to form a regular grid layout, which is distributed in accordance with the outline of the top surface of the chilled iron. The outer diameter of the circular boss is set to be smaller than the inner diameter of the corresponding sand mold hole, forming a clearance fit positioning structure; the top surface diameter of the chill body is adapted to the area occupied by the sand mold hole group in the sand mold.

2. A conical frustum shaped chills for sand casting cylinder head fire surfaces according to claim 1, characterized in that, The total height of the chill body is 20-30mm, the height of the upper truncated cone is 12-18mm, and the height of the lower truncated cone is 8-12mm.

3. The frustum-shaped chill for the fire-heating surface of a sand-cast cylinder head according to claim 1, characterized in that, The chill body is made of low-carbon steel or copper.

4. The frustum-shaped chill for the fire-heating surface of a sand-cast cylinder head according to claim 1, characterized in that, The exhaust groove adopts a refined narrow groove design, with the width of a single exhaust groove controlled at 0.8 to 1.2 mm and the groove depth set at 1 to 1.2 mm.

5. A frustum-shaped chill for the fire-heating surface of a sand-cast cylinder head according to claim 1, characterized in that, The chill body is designed as a waist-shaped truncated cone, and its contact surface with the sand mold is a waist-shaped inclined surface structure.

6. A frustum-shaped chill for the fire-heating surface of a sand-cast cylinder head according to claim 1, characterized in that, After the truncated cone-shaped chill is sandblasted to remove rust and scale, it is coated with a high-temperature resistant coating to prevent the chill from sticking to the casting.

7. A frustum-shaped chill for the fire-heating surface of a sand-cast cylinder head according to claim 1, characterized in that, The circular bosses have a diameter of 5-8mm and number 4-6, and are evenly distributed along the radial direction of the top surface of the upper cone.

8. A frustum-shaped chill for the fire-heating surface of a sand-cast cylinder head according to claim 1, characterized in that, The upper end of the circular boss protrudes 2mm beyond the top surface of the upper cone.

9. A frustum-shaped chill for the firing surface of a sand-cast cylinder head according to claim 1, characterized in that, The circular boss has a standard circular cross-section.

10. A frustum-shaped chill for the firing surface of a sand-cast cylinder head according to claim 1, characterized in that, The exhaust groove is located on the top surface of the circular boss.

Images