A vertical parting casting mold and a casting method for a vehicle belt pulley

Abstract

The present application relates to the technical field of casting, and particularly relates to a vertical parting casting mold and casting method for an automobile belt pulley. The mold comprises a first mold and a second mold, the first mold is provided with a first casting body, an annular cross gate, an inner gate, a clear riser and a first pouring cup; the annular cross gate is arranged around the periphery of the cavity; the inner gate is located at the lower part of the cavity and is communicated with the cavity; the clear riser is arranged directly above the cavity, the bottom of the clear riser is communicated with the cavity, the side of the clear riser is communicated with the upper part of the annular cross gate, and the communication point is B; and the communication point of the first pouring cup and the annular cross gate is A. In the vertical direction, the communication point A is higher than the communication point B, and the height difference ΔH between the two satisfies the relationship: ΔH=(0.4-0.6)r+k*ΔG. The present application can realize quick and stable filling of vertical parting casting of heavy belt pulleys, effectively improve the quality of the castings, and can quickly adapt to the mold design of multiple specifications of products, and has strong universality and high mold changing efficiency.

Description

Technical Field

[0001] This invention relates to the field of casting technology, and in particular to a vertical parting mold and casting method for automobile pulleys. Background Technology

[0002] Ductile iron pulleys are widely used in the automotive and other fields due to their excellent mechanical properties. With the increasing level of production automation, vertical parting automatic molding lines (such as the DISA line) are widely used in mass production due to their high efficiency and high precision.

[0003] However, when vertically parting casting heavy-duty automotive pulleys weighing 40kg to 60kg, existing processes and mold structures have significant technical defects, making it difficult to meet the demands of high-quality mass production. Firstly, heavy-duty pulley castings are large in size, have large cavity volumes, and require a large volume of molten iron. Existing vertical parting casting molds have fixed gating system structures, limiting the filling speed and preventing rapid filling of large-volume cavities. The molten iron filling process is slow, with significant temperature drops along the way, easily leading to incomplete filling of the casting. This results in frequent casting defects such as cold shuts, shrinkage porosity, and insufficient filling, severely affecting the appearance quality and internal density of the casting.

[0004] Secondly, existing vertical parting casting molds are mostly fixed, dedicated structures. The mold gating system and static pressure height are designed for single-specification castings, lacking versatility and adaptability. When dealing with multi-specification castings, such as heavy-duty pulleys with varying outer diameters and weights, companies must rely on engineering experience to repeatedly adjust and re-match the mold's gating structure and pouring height when changing the mold design to match the product model. This requires multiple trial runs, mold repairs, and parameter adjustments to meet production requirements. This not only significantly extends the product changeover cycle but also substantially increases mold development and trial material costs, resulting in low production efficiency and severely hindering the efficient and universal application of automated vertical parting production lines. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a vertical parting casting mold and casting method for automotive pulleys. By optimizing the gating system structure and adjusting the static pressure height, this invention effectively solves the casting defects such as slow filling speed and cold shuts that occur during the vertical parting casting process of heavy-duty pulleys. Furthermore, this invention establishes the relationship between the height difference ΔH and the weight and dimensions of pulley castings of different specifications, thereby enabling the rapid design of molds for pulley castings of different specifications.

[0006] The technical solution adopted by this invention to solve its technical problem is: a vertical parting casting mold for automobile pulleys, characterized in that: it includes a first mold and a second mold, wherein the sand molds prepared by the first mold and the second mold are fitted together to form a pulley cavity; the first mold is provided with: The first casting body is used to form a portion of the pulley cavity; An annular horizontal runner surrounds the periphery of the pulley cavity; The inner gating system is located below the annular horizontal gating system, with one end connected to the annular horizontal gating system and the other end connected to the pulley cavity. An exposed riser is located directly above the pulley cavity, with its bottom connected to the pulley cavity and its side connected to the upper part of the annular horizontal runner. The connection point between the exposed riser and the pulley cavity is B. The first pouring cup is connected to the annular horizontal runner, with connection point A. In the vertical direction, connection point A16 is higher than connection point B17. The height difference ΔH between connection point A16 and connection point B17 satisfies the following relationship: ΔH = (0.4~0.6)r + k×ΔG; where r is the outer diameter of the pulley casting to be produced, in mm; k is the weight compensation coefficient, k = 1.2mm / kg~1.8mm / kg; and ΔG is the weight difference between the pulley casting to be produced and a preset reference pulley casting. The second mold is provided with a second casting body for forming another part of the pulley cavity.

[0007] Furthermore, the preset reference weight is 40kg, and the weight of the pulley casting is 40kg to 60kg.

[0008] Furthermore, the cross-sectional area of ​​the inner gating system is S, and the cross-sectional area of ​​the annular horizontal gating system is s, where S / s = 1.5-2.5.

[0009] Furthermore, when the weight of the casting is 40kg to 50kg, two ingates are arranged, and when the weight of the casting is 50kg to 60kg, three ingates are arranged.

[0010] Furthermore, when the weight of the casting is 40kg to 50kg, k is 1.2mm / kg to 1.5mm / kg; when the weight of the casting is 50kg to 60kg, k is 1.5mm / kg to 1.8mm / kg.

[0011] Furthermore, the thickness d of the riser satisfies d = (0.1 ~ 0.25)r + 0.2 × ΔG.

[0012] Furthermore, the connecting point A16 is a fixed height reference point, and its vertical distance from the top of the first pouring cup remains constant.

[0013] On the other hand, a vertical parting casting method for an automobile pulley, using a vertical parting casting mold for an automobile pulley as described in any one of claims 1 to 7, includes the following steps: S1. Based on the actual weight G and outer diameter r of the belt pulley casting to be produced, calculate the weight gain difference ΔG relative to the 40kg reference weight. According to the formula ΔH=(0.4~0.6)r+k×ΔG, determine the height difference between connected point A16 and connected point B17, and design the first mold and the second mold. S2. Based on the design of the first mold and the second mold, make sand molds, and then put the sand molds made by the two molds together to obtain a casting cavity with a gating system. S3. The molten ductile iron is introduced into the annular horizontal runner from the first pouring cup. Relying on the calibrated static pressure height difference ΔH formed by the connection point A at a fixed height and the connection point B with adaptive displacement, the molten iron is smoothly and uniformly filled into the inside of the belt pulley casting cavity through the inner runner. S4. After the casting has completely cooled and solidified, open the mold along the vertical parting surface, remove the casting, and clean, grind, and inspect the casting gate, riser allowance, and burrs to complete the finished product preparation.

[0014] Furthermore, in step S3, the pouring temperature of the ductile iron molten iron is controlled at 1380℃~1430℃, and the pouring speed of the casting is 3kg / s~4kg / s.

[0015] Furthermore, in step S4, the casting is naturally cooled in the sand mold to below 400°C before being unpacked. It is then placed in a holding furnace for controlled cooling at a rate of 20°C / h to 40°C / h until it reaches room temperature.

[0016] The beneficial effects of this invention are:

[0017] 1. In this invention, by setting the connecting point A16 higher than the connecting point B17, a reasonable pouring sequence is ensured during the casting process: the mold cavity is filled first, followed by the riser. Furthermore, the gravity static pressure formed by this height difference ΔH provides sufficient and continuous filling power for the molten iron to fill the large mold cavity, effectively overcoming the deficiency of insufficient filling power in traditional molds. Simultaneously, by setting an open riser that connects the top to the atmosphere, this invention facilitates the rapid removal of gas from the mold cavity during pouring, thereby significantly reducing the flow resistance of the molten iron during filling. Through the combined effect of the gravity static pressure formed by the height difference and the open riser structure, this invention achieves rapid and stable filling of the molten iron, shortens the overall filling time, and reduces the temperature drop of the molten iron within the mold cavity, thus effectively avoiding casting defects such as cold shuts and incomplete pouring caused by slow filling and large temperature differences in the molten iron.

[0018] 2. This invention establishes a quantitative relationship between the height difference ΔH and the outer diameter r and weight gain difference ΔG of pulley castings of different specifications. For pulleys of different specifications, there is no need to redevelop the entire mold. Based on this relationship, the key parameters of the mold (such as static pressure height, number of ingates and riser thickness) can be designed quickly and accurately. This allows for the rapid completion of the customized design of the corresponding mold, effectively eliminating the need for repeated mold trials and repairs based on experience. It significantly shortens the product changeover design and production cycle, reduces mold development and trial production costs, and realizes efficient and universal production of vertical parting automated production lines. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the first mold and the second mold of the present invention.

[0020] Figure 2 This is a schematic diagram of the structure of the first mold of the present invention.

[0021] Figure 3 This is a schematic diagram of the structure of the second mold of the present invention.

[0022] Figure 4 This is a schematic diagram of the structure of the blank casting without the first pouring cup obtained after pouring according to the present invention.

[0023] Explanation of reference numerals in the attached figures: 10. First mold; 11. First casting body; 12. Annular runner; 13. Ingate; 14. Riser; 15. First pouring cup; 16. Connecting point A; 17. Connecting point B; 20. Second mold; 21. Second casting body. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0025] like Figure 1-4As shown, an embodiment of the present invention provides a vertical parting casting mold for an automobile pulley, including a first mold 10 and a second mold 20. The sand molds prepared by the first mold 10 and the second mold 20 are fitted together to form a pulley cavity. The first mold 10 is provided with a first mold body 11, an annular horizontal runner 12, an ingate 13, an exposed riser 14, and a first pouring cup 15. The first mold body 11 is used to form a portion of the pulley cavity 70. The annular horizontal runner 12 surrounds the periphery of the pulley cavity 70. The ingate 13 is located below the annular horizontal runner 12, with one end connected to the annular horizontal runner 12 and the other end connected to the pulley cavity 70. The exposed riser 14 is located directly above the pulley cavity 70, with its bottom connected to the pulley cavity 70 and its side connected to the upper part of the annular horizontal runner 12. The connection point between the exposed riser 14 and the pulley cavity 70 is B. The first pouring cup 15 is connected to the annular horizontal runner 12, with the connection point being A. In the vertical direction, the connection point A16 is higher than the connection point B17. The height difference ΔH between the connection points A16 and B17 satisfies the following relationship: ΔH = (0.4~0.6)r + k×ΔG; where r is the outer diameter of the pulley casting to be produced, in mm; k is the weight compensation coefficient, k = 1.2mm / kg~1.8mm / kg; and ΔG is the weight difference between the pulley casting to be produced and a preset reference pulley casting. The second mold 20 is provided with a second mold body 21 and a second pouring cup for forming another part of the pulley cavity 70.

[0026] The mold of this invention, by setting the connection point A16 of the first pouring cup 15 above the connection point B17 of the open riser 14, utilizes this height difference ΔH to form a stable gravitational static pressure during the pouring process. This provides continuous and sufficient power for the molten iron to fill the large pulley cavity 70 through the annular horizontal runner 12 and the ingate 13, effectively overcoming the problem of slow filling caused by insufficient filling power in traditional molds. Simultaneously, the open riser 14, located directly above the cavity and open to the atmosphere at its top, provides a smooth outlet for gas inside the cavity, significantly reducing the flow resistance of the molten iron during the filling process. The combined effect of these structures enables rapid and stable filling of 40kg-60kg heavy pulley castings, shortening the filling time and reducing the temperature drop of the molten iron, thereby effectively avoiding casting defects such as cold shuts and incomplete pouring. Furthermore, the open riser of this invention can collect slag and provide continuous feeding, effectively compensating for the solidification shrinkage of the casting, reducing shrinkage defects, and improving the overall forming quality and internal density of the casting.

[0027] The static pressure height difference calculation formula designed in this invention is ΔH=(0.4~0.6)r+k×ΔG. Based on the differentiated structural characteristics of heavy-duty pulleys and the solidification characteristics of vertical parting filling, it achieves precise matching of casting static pressure for heavy-duty pulleys with different outer diameters and weight specifications. The preset benchmark weight of this invention is 40kg, and the weight of the pulley casting is 40kg~60kg. This benchmark is set as the starting point for the universal design of the mold, which facilitates formula calculation and parameter adjustment.

[0028] In the above formula, (0.4~0.6)r is the dimensional reference static pressure term, and r is the actual outer diameter of the pulley to be produced. The outer diameter of the pulley directly determines the length of the filling path and the flow resistance along the casting cavity. The larger the outer diameter, the longer the molten iron filling process and the higher the resistance loss. Using the actual outer diameter of the casting as a reference to construct the basic static pressure height, the corresponding basic filling power can be matched according to the filling resistance difference of castings of different sizes, ensuring that pulleys of different outer diameter specifications can obtain suitable basic filling pressure, avoiding defects such as slow filling, cold shut, and incomplete pouring in large-diameter castings due to insufficient static pressure, while preventing molten iron turbulence and slag entrapment problems caused by excessive static pressure in small-diameter castings.

[0029] In the above formula, k×ΔG is the weight compensation term, where ΔG is the weight difference between the current casting and the reference weight, and k is the compensation coefficient for the corresponding weight range. This compensation term addresses the increased demand for molten iron and intensified solidification shrinkage caused by the increased weight of the casting. As the casting weight increases from the reference value of 40kg to 60kg, the total amount of molten iron required increases significantly, and the volume shrinkage during solidification also increases. If the static pressure height is not adjusted accordingly, it will be difficult to maintain stable filling and effective feeding. By introducing the k×ΔG term, the static pressure height can be dynamically increased according to the actual weight increase, ensuring that the heavy-duty pulley still has sufficient feeding pressure in the later stages of filling, thereby suppressing the formation of internal defects such as shrinkage porosity and shrinkage cavities.

[0030] The overall casting process of the sand mold cavity prepared by the mold of the present invention is as follows: molten iron is poured into the first pouring cup 15, first entering the annular horizontal sprue 12. Driven by the static pressure head formed by the height difference ΔH between the connecting point A16 and the connecting point B17, the molten iron quickly fills the annular horizontal sprue 12, and preferentially enters the bottom of the pulley cavity 70 smoothly and uniformly through the lower ingate 13, realizing sequential filling from bottom to top. After the cavity 70 is basically filled, the molten iron enters the open riser 14 through the connection between the side of the open riser 14 and the upper part of the annular horizontal sprue 12, finally forming a complete casting.

[0031] In this invention, the cross-sectional area of ​​the ingate 13 is S, and the cross-sectional area of ​​the annular horizontal sprue 12 is s, with S / s = 1.5-2.5. By making the cross-sectional area of ​​the ingate 13 larger than that of the annular horizontal sprue 12, it is ensured that the molten iron flows smoothly from the annular horizontal sprue 12 to each ingate 13, reducing resistance and avoiding turbulence or air intake at the connection points, thus facilitating the smooth entry of the molten iron into the mold cavity. As a specific implementation, the S / s ratio is preferably 1.8-2.2, within which better filling stability can be achieved.

[0032] When the casting weight is 40kg to 50kg, two ingates 13 are arranged; when the casting weight is 50kg to 60kg, three ingates 13 are arranged. By adjusting the number of ingates 13 according to the casting weight, the filling flow can be reasonably distributed to ensure that the cavity of large and heavy castings can be replenished with molten iron simultaneously and evenly, and to prevent local insufficient filling.

[0033] For castings in different weight ranges, the weight compensation coefficient k is refined: when the casting weight is 40kg to 50kg, k is 1.2mm / kg to 1.5mm / kg; when the casting weight is 50kg to 60kg, k is 1.5mm / kg to 1.8mm / kg. Since heavier castings require greater filling power to overcome flow resistance within the mold cavity and maintain sufficient end pressure, the value of k increases with weight, allowing the height difference ΔH to more accurately match the filling power requirements of castings of different weights.

[0034] In this invention, the thickness d of the exposed riser 14 satisfies d = (0.1~0.25)r + 0.2×ΔG. Thickness d refers to the dimension of the exposed riser along the axial direction of the first casting body, or the dimension of the exposed riser perpendicular to the first mold. Based on the weight and size of different pulley castings, sufficient volume and feeding capacity of the exposed riser 14 are ensured. Its thickness d is appropriately increased with the outer diameter r and weight increment ΔG of the casting, allowing the exposed riser to effectively accommodate the rising molten iron in the later stages of pouring and compensate for the solidification shrinkage of the casting. Furthermore, the width l of the exposed riser = (0.45-0.6)r, where the width l refers to the dimension along the length direction of the first mold, i.e., along... Figure 1In the horizontal direction, the connection between the riser and the pulley cavity is arc-shaped, and the chord length corresponding to the arc is equal to the width l of the riser. For a larger outer diameter r of the casting, a smaller coefficient is chosen, such as l = (0.45-0.5)r; for a smaller outer diameter r, a larger coefficient is chosen, such as l = (0.5-0.6)r. This allows for the formation of a gate at the top of the cavity, facilitating a smooth transition of molten iron to the riser area at the end of the filling process, avoiding eddies or gas entrapment caused by sudden flow changes. Furthermore, this width range ensures sufficient cross-sectional area between the riser and the cavity, maintaining good feeding channel unobstructed while ensuring venting efficiency. This allows for continuous backflow of molten metal during solidification, further improving the density and mechanical property consistency of the casting.

[0035] In this invention, the connecting point A16 is a fixed height reference point, meaning its vertical distance from the top of the first gating cup 15 remains constant. That is, the connection position between the first gating cup 15 and the annular runner 12 is fixed. The adjustment of the height difference ΔH is mainly achieved by changing the vertical position of the connecting point B17 at the bottom of the riser 14. This simplifies the complexity of mold structure adjustment and improves the operability of the design.

[0036] This invention also provides a vertical parting casting method for automotive pulleys, which uses the vertical parting casting mold for automotive pulleys as described above for production, and includes the following steps:

[0037] S1. Based on the actual weight G and outer diameter r of the belt pulley casting to be produced, calculate the weight gain difference ΔG relative to the 40kg reference weight. According to the formula ΔH=(0.4~0.6)r+k×ΔG, determine the height difference between the connected point A16 and the connected point B17, and determine the number of ingates 13, the thickness d of the riser 14, and other parameters to design the first mold 10 and the second mold 20.

[0038] S2. Based on the design of the first mold 10 and the second mold 20, make sand molds, and then put the sand molds made by the two molds together to obtain a casting cavity with a complete gating system.

[0039] S3. Molten ductile iron is introduced into the annular horizontal runner 12 through the first pouring cup 15. Relying on the calibrated static pressure height difference ΔH formed by the connection point A at a fixed height and the connection point B at a position determined according to the design, the molten iron is smoothly and uniformly filled into the inside of the pulley casting cavity 70 through the inner runner 13. The pouring temperature of the ductile iron is controlled at 1380℃~1430℃, and the pouring speed of the casting is 3kg / s~4kg / s.

[0040] S4. After the casting has completely cooled and solidified, open the mold along the vertical parting surface, remove the casting, and clean, grind, and inspect the casting gate, riser allowance, and flash burrs to complete the finished product preparation. Among them, the casting is naturally cooled in the sand mold to below 400℃ before being opened, and then placed in a holding furnace for controlled cooling at a rate of 20℃ / h to 40℃ / h until room temperature, in order to obtain the ideal ductile iron pulley.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A vertical parting casting mold for an automobile pulley, characterized in that: It includes a first mold and a second mold, wherein the sand molds prepared by the first mold and the second mold are mated to form a pulley cavity; the first mold is provided with: The first casting body is used to form a portion of the pulley cavity; An annular horizontal runner surrounds the periphery of the pulley cavity; The inner gating system is located below the annular horizontal gating system, with one end connected to the annular horizontal gating system and the other end connected to the pulley cavity. An exposed riser is located directly above the pulley cavity, with its bottom connected to the pulley cavity and its side connected to the upper part of the annular horizontal runner. The connection point between the exposed riser and the pulley cavity is B. The first pouring cup is connected to the annular horizontal runner, with connection point A. In the vertical direction, connection point A16 is higher than connection point B17. The height difference ΔH between connection point A16 and connection point B17 satisfies the following relationship: ΔH = (0.4~0.6)r + k×ΔG; where r is the outer diameter of the pulley casting to be produced, in mm; k is the weight compensation coefficient, k = 1.2mm / kg~1.8mm / kg; and ΔG is the weight difference between the pulley casting to be produced and a preset reference pulley casting. The second mold is provided with a second casting body for forming another part of the pulley cavity.

2. The vertical parting casting mold for an automobile pulley according to claim 1, characterized in that, The preset benchmark weight is 40kg, and the weight of the pulley casting is 40kg to 60kg.

3. The vertical parting casting mold for an automobile pulley according to claim 1, characterized in that, The cross-sectional area of ​​the ingate is S, and the cross-sectional area of ​​the annular horizontal runner is s, where S / s = 1.5-2.

5.

4. The vertical parting casting mold for an automobile pulley according to claim 2, characterized in that, When the weight of the casting is 40kg to 50kg, two ingates are arranged; when the weight of the casting is 50kg to 60kg, three ingates are arranged.

5. The vertical parting casting mold for an automobile pulley according to claim 2, characterized in that, When the weight of the casting is 40kg to 50kg, k is 1.2mm / kg to 1.5mm / kg; when the weight of the casting is 50kg to 60kg, k is 1.5mm / kg to 1.8mm / kg.

6. The vertical parting casting mold for an automobile pulley according to claim 2, characterized in that, The thickness d of the riser satisfies d = (0.1 ~ 0.25)r + 0.2 × ΔG.

7. The vertical parting casting mold for an automobile pulley according to claim 2, characterized in that, The connecting point A16 is a fixed height reference point, and its vertical distance from the top of the first pouring cup remains constant.

8. A vertical parting casting method for automobile pulleys, characterized in that, The vertical parting casting mold for an automobile pulley according to any one of claims 1 to 7 includes the following steps: S1. Based on the actual weight G and outer diameter r of the belt pulley casting to be produced, calculate the weight gain difference ΔG relative to the 40kg reference weight. According to the formula ΔH=(0.4~0.6)r+k×ΔG, determine the height difference between connected point A16 and connected point B17, and design the first mold and the second mold. S2. Based on the design of the first mold and the second mold, make sand molds, and then put the sand molds made by the two molds together to obtain a casting cavity with a gating system. S3. The molten ductile iron is introduced into the annular horizontal runner from the first pouring cup. Relying on the calibrated static pressure height difference ΔH formed by the connection point A at a fixed height and the connection point B with adaptive displacement, the molten iron is smoothly and uniformly filled into the inside of the belt pulley casting cavity through the inner runner. S4. After the casting has completely cooled and solidified, open the mold along the vertical parting surface, remove the casting, and clean, grind, and inspect the casting gate, riser allowance, and burrs to complete the finished product preparation.

9. A vertical parting casting method for an automobile pulley according to claim 8, characterized in that, In step S3, the pouring temperature of the ductile iron molten iron is controlled at 1380℃~1430℃, and the pouring speed of the casting is 3kg / s~4kg / s.

10. A vertical parting casting method for an automobile pulley according to claim 8, characterized in that, In step S4, the casting is naturally cooled in the sand mold to below 400°C before being unpacked. It is then placed in a holding furnace for controlled cooling at a rate of 20°C / h to 40°C / h until it reaches room temperature.

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