Aluminum Alloy Casting Fan Blade Production Process

Abstract

The present invention belongs to the technical field of fan blade production and application, and in particular to a production process of aluminum alloy casting fan blades. The present invention effectively realizes rapid casting by limiting the raw materials and coordinating the improvement of the process and the mold, reduces the storage time of the aluminum liquid, and increases the cooling speed of the blades, thereby improving the product yield. At the same time, the present invention is simple to operate and suitable for large-scale promotion and use.

Description

Technical Field

[0001] The invention belongs to the technical field of fan blade production and application, and in particular relates to a production process of aluminum alloy casting fan blades. Background Art

[0002] Aluminum alloy casting fan blades are important components of large fans. Large fans are mainly used in thermal power plants, chemical enterprises, tunnels and other industrial and mining enterprises. When used in harsh environments such as high temperature and corrosion, they must withstand large alternating loads. Therefore, the internal and external quality requirements of the blades are very high. Blades are not allowed to be repaired or welded, and heat treatment deformation correction is required to be completed within the specified time and aging treatment is performed.

[0003] Due to the large number of fan models, there are also many types of corresponding blades. Their lengths range from 400 to 1500mm, but their geometric shapes are basically the same. The plane projection of the blade is willow-shaped, and the cross-section of the blade is a shuttle-shaped section. The curvature of the blade surface and the back of the blade is large; the longitudinal thickness is smooth and thin from the root to the tip of the blade; the edge of the entire blade is very thin, only 2~3mm thick; the blade axis size at the root of the blade is Ф100~200mm, the blade shape is spatially distorted, and the thickness difference is large. The blade is a slender and unequal thickness piece with spatial distortion and smoothness, and the edge is extremely thin, which is difficult to cast.

[0004] Although the traditional casting method can also achieve the molding of blades, it has technical problems such as low yield rate, many burrs, and long grinding time. Summary of the invention

[0005] In view of the technical problems existing in the above-mentioned aluminum alloy casting fan blade production process, the present invention proposes an aluminum alloy casting fan blade production process which is simple in method, easy to operate and can effectively improve the yield rate of blades.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is that the present invention provides a production process of aluminum alloy casting fan blades, comprising the following steps:

[0007] a. First, use a low-pressure crucible furnace to process pure aluminum with a purity of more than 99.85% and auxiliary materials into aluminum alloy liquid for standby use;

[0008] b. While heating the aluminum alloy liquid, the mold required for casting is heated to a certain temperature and then sprayed with coating. During spraying, the spraying thickness of the mold in the middle part of the blade is less than the thickness at both ends. The overall structure of the mold is vertical parting, and a gate is set at the round and thick part of the blade root. The mold is divided into three parts: upper, middle and lower based on the length of the blade. The thermal conductivity of the material in the upper part is the largest, the thermal conductivity of the material in the middle part is the second largest, and the thermal conductivity of the material in the lower part is the smallest.

[0009] c. After the casting is completed, take the blade blank out of the mold, remove the pouring head according to the cutting line, and grind the burrs flat;

[0010] d. Carry out solution treatment according to the casting furnace, and perform shape correction immediately after solution treatment;

[0011] e. After the calibration is completed, use the centerline gauge to check to ensure that the blade gap is less than 1mm and the blade root gap is less than 0.5mm. Then use the horizontal angle gauge and depth gauge to check the torsion angle and chord height respectively. After all are qualified, carry out aging treatment to obtain the required fan blade;

[0012] Wherein, in the step b, a compressed air cooling channel is provided on the mold required for casting, and the diameter of the compressed air cooling channel gradually decreases from the bottom of the mold upward.

[0013] Preferably, in step a, during the process of smelting the aluminum alloy liquid in a low-pressure crucible furnace, argon gas is used for refining and degassing, and the aluminum alloy liquid is subjected to modification and refinement treatment.

[0014] Preferably, in step b, a compressed air cooling channel is provided on the mold required for casting.

[0015] Preferably, the diameter of the compressed air cooling channel gradually decreases from the bottom of the mold upwards.

[0016] Preferably, exhaust ports are provided on both sides of the gate.

[0017] Compared with the prior art, the advantages and positive effects of the present invention are as follows: the present invention provides a production process for aluminum alloy casting fan blades, which effectively realizes rapid casting by limiting the raw materials and coordinating the improvements in the process and the mold, reduces the storage time of the aluminum liquid, and increases the cooling rate of the blades, thereby improving the yield rate of the product. At the same time, the present invention is simple to operate and is suitable for large-scale promotion and use. DETAILED DESCRIPTION

[0018] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below in conjunction with embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0019] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.

[0020] Embodiment 1: This embodiment provides a production process of aluminum alloy casting fan blades.

[0021] The first step is to melt the raw materials to obtain aluminum alloy liquid. For this purpose, the raw materials are required to purchase pure aluminum with a purity higher than 99.85%, and are configured into aluminum alloy liquid that meets the composition requirements of ENAC42100 during production. The composition and hydrogen content of each furnace are tested, and casting can only be carried out after the test results are qualified.

[0022] In order to reduce the increase of gas content in aluminum liquid caused by the turnover of aluminum liquid in low-pressure casting, a low-pressure crucible furnace that can be degassed is used in low-pressure casting. At the same time, argon is used for refining and degassing, and the aluminum liquid needs to be modified and refined. Modification and refinement can be achieved by adding refiners and modifiers. The main purpose is to improve the grain refinement and prevent casting cracks, so as to achieve the purpose of improving the yield rate.

[0023] In the smelting process, the melting should be fast, and the casting process should also be shortened as much as possible to reduce the storage time of the aluminum liquid. To this end, in this embodiment, the overall structure of the mold is vertical and parted, and a gate is set at the round and thick part of the blade root. At the same time, exhaust ports are set on both sides of the gate.

[0024] Specifically, when designing the mold, the blade is first split into two blade modules from the center line of the blade length. The blade modules are provided with pin holes and fastening holes. When in use, the mold is arranged up and down with the root of the blade at the top. In this way, gravity can be used to make the aluminum alloy liquid fall quickly, thereby completing the filling of the inside of the mold.

[0025] In order to facilitate the spraying of the coating, the coating is sprayed when the mold required for casting is heated to a certain temperature (about 380°C). It should be noted here that the spraying thickness of the mold in the middle part of the blade is less than the thickness at both ends. This is to accelerate the rapid cooling of the middle part of the blade, so that its structure is fine and the morphology of the second phase is also fine. This is because the deformation of the middle part of the blade is the largest, and its greater strength is conducive to overall molding and plays a better connection role. At the same time, the mold is divided into three parts: upper, middle and lower, based on the length of the blade. Among them, the thermal conductivity of the upper part material is the largest, the thermal conductivity of the middle part material is second, and the thermal conductivity of the lower part material is the smallest. The purpose of this setting is mainly to form unequal temperature zones within the same heating time. The traditional method is to heat in sections and heat to different temperatures, which is inefficient and the waiting time for the aluminum alloy liquid is long. Different heat-conducting materials are used as the materials of the mold to form partitions, thereby achieving the purpose of forming different temperature zones. Considering the connection problem of different heat-conducting materials, in this embodiment, the material of the mold shell is consistent, and only the part in contact with the filtrate is made into a block, which can be connected by bolts.

[0026] At the same time, in order to ensure that the cooling time at both ends is closer, in this embodiment, a compressed air cooling channel is provided on the mold required for casting. The diameter of the compressed air cooling channel gradually decreases from the bottom of the mold upward. In this way, since the thermal conductivity of the bottom of the blade is low, its cooling channel is large and the wind speed is slow, while the thermal conductivity of the root of the blade is large, and its cooling channel is small, so the wind speed is fast. In summary, the cooling time of the two is closer. Since the cooling speed of the middle part is fast, a sequential solidification from the middle to both sides is formed, thereby ensuring the molding. Ensure that the organization is dense, and there are no large defects such as shrinkage and shrinkage holes.

[0027] After cooling is completed, the blade blank is taken out of the mold, the pouring spout is removed along the cutting line, and the burrs are polished smooth to facilitate dimensional correction after solutionizing.

[0028] The blades are loaded into the furnace for solution treatment according to the casting furnace. After solution treatment, they are immediately calibrated and dimension checked. It is required that all products after solution treatment are calibrated within the specified time to prevent the hardness of the product from increasing over time, which will increase the risk of cracks in the blades. After the calibration is completed, the centerline gauge is used for inspection. The blade clearance is required to be less than 1mm and the blade root clearance is less than 0.5mm. The torsion angle and chord height are respectively tested with a horizontal angle gauge and a depth gauge. After all are qualified, aging treatment is carried out.

[0029] After testing, the qualified rate of products in one batch can reach 90%, which is much higher than the 80% yield rate of traditional casting process, and is suitable for large-scale promotion and use.

[0030] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A production process for aluminum alloy casting fan blades, characterized in that: The following steps are involved: a. First, use a low-pressure crucible furnace to process pure aluminum with a purity of more than 99.85% and auxiliary materials into aluminum alloy liquid for standby use; b. While heating the aluminum alloy liquid, the mold required for casting is heated to a certain temperature and then sprayed with coating. During spraying, the spraying thickness of the mold in the middle part of the blade is less than the thickness at both ends. The overall structure of the mold is vertical parting, and a gate is set at the round and thick part of the blade root. The mold is divided into three parts: upper, middle and lower based on the length of the blade. The thermal conductivity of the material in the upper part is the largest, the thermal conductivity of the material in the middle part is the second largest, and the thermal conductivity of the material in the lower part is the smallest. c. After the casting is completed, take the blade blank out of the mold, remove the pouring head according to the cutting line, and grind the burrs flat; d. Carry out solution treatment according to the casting furnace, and perform shape correction immediately after solution treatment; e. After the calibration is completed, use the centerline gauge to check to ensure that the blade gap is less than 1mm and the blade root gap is less than 0.5mm. Then use the horizontal angle gauge and depth gauge to check the torsion angle and chord height respectively. After all are qualified, carry out aging treatment to obtain the required fan blade; Wherein, in the step b, a compressed air cooling channel is provided on the mold required for casting, and the diameter of the compressed air cooling channel gradually decreases from the bottom of the mold upward.

2. The aluminum alloy casting fan blade production process according to claim 1 is characterized in that: In the step a, during the process of melting the aluminum alloy liquid in the low-pressure crucible furnace, argon gas is used for refining and degassing, and the aluminum alloy liquid is subjected to modification and refinement treatment.

3. The aluminum alloy casting fan blade production process according to claim 2 is characterized in that: Exhaust ports are arranged on both sides of the gate.