CN113319250A - Manufacturing method of 2.8MW wind power hub - Google Patents

Abstract

The invention discloses a method for manufacturing a 2.8MW wind power hub, which comprises the following steps: step (1), sand releasing; step (2), placing a proper chilling block at the boss position of the casting and selecting a proper air outlet area; step (3), smelting; step (4), spheroidizing inoculation; and (5) pouring. The preparation method is simple, the operation is simple and convenient, the efficiency is high, a filter screen and a riser are not needed, and only a small amount of chilling blocks are used. The internal structure of the casting is compact, the ultrasonic flaw detection and the magnetic particle flaw detection meet the requirements, the surface of the casting is smooth and clean, the polishing workload is small, the structure of the whole casting is relatively balanced, the difference is small, and the mechanical property of the whole casting is excellent.

Description

Manufacturing method of 2.8MW wind power hub

Technical Field

The invention belongs to the field of metallurgy, and particularly relates to a method for manufacturing a 2.8MW wind power hub, which fully utilizes the graphitization expansion of nodular cast iron by optimizing a casting head system, controlling alloy elements and controlling a spheroidizing inoculation process, and ensures that the produced casting has excellent tissue and performance.

Background

The wind power hub is an important core component of wind power generation equipment, is a part for connecting a blade and a main shaft, and is used for bearing thrust, torque, bending moment and gyroscopic moment acted on the blade by wind power and then transmitting the force and the moment of a wind wheel to a mechanism. The wind turbine generator is mostly built on coastal or desert areas and operates at high altitude all year around, and generally works at a low temperature of-20 ℃ or even-40 ℃, and the wind speed changes greatly during working. The wind power casting has a severe operating environment, so that the requirement on the quality performance index of the casting is high. The wind power hub belongs to a thick and large section ferrite-based nodular iron casting, and due to the fact that the section is too large, cooling speed is slow, solidification time is long, graphite distortion, spheroidization recession, broken graphite blocks, reverse white cast and other defects are prone to occurring at the center or a hot spot of the thick and large section, mechanical performance is reduced, in addition, 100% of ultrasonic flaw detection and surface magnetic powder inspection are needed for the wind power hub, and high stress key areas of a main shaft and a blade face reach level 2. The technical difficulties for producing the nodular cast iron of the wind power wheel hub are as follows:

(1) how to solve the problem of internal shrinkage porosity of castings

(2) How to solve the oxidation slag in the molten iron and avoid the inclusion in the casting and obtain good casting

(3) How to ensure that a thick and large section can obtain good spheroidization rate, avoid anisotropic graphite, obtain a ferrite matrix structure of more than 90 percent in a casting state, and ensure enough strength and low-temperature impact toughness

In order to solve the difficulties, most manufacturers adopt a filter screen and place a large amount of chills and risers to solve the problems of slag inclusion, shrinkage porosity and organization, thereby not only increasing the production cost and the polishing workload, but also bringing other problems.

Disclosure of Invention

The purpose of the invention is as follows: in order to solve the defects of the prior art, the invention provides a manufacturing method of a 2.8MW wind power hub, which solves the problems of loose structure, graphite distortion, oxidation slag inclusion and the like of a thick and large section wind power hub and improves the performance of a casting.

The technical scheme is as follows: a manufacturing method of a 2.8MW wind power hub comprises the following steps:

step (1), sand releasing: jolting and tamping when releasing sand, controlling the tensile strength of the sand mould, wherein the tensile strength of the sand mould after the resin sand is solidified is more than or equal to 1.2 Mpa;

step (2), placing a proper chiller at the boss position of the casting and selecting a proper air outlet area: a chill is placed at the boss part of the casting, the thickness of the chill is 0.5-1 time of that of the boss, and the gas outlet area is more than 1.5 times of that of the sprue;

step (3), smelting: smelting by adopting high-purity pig iron and scrap steel, and controlling the total content of trace impurity elements to be lower than 0.15%;

step (4), spheroidizing inoculation: 0.8-1.0% of nodulizer and 0.3-0.6% of inoculant for covering are sequentially added into the nodulizing ladle, and 30-80ppm of Sb is added during nodulizing; standing for 5-10 minutes after spheroidizing and then slagging; c in molten iron after spheroidizing treatment: 3.65-3.75%, Si: 2.0-2.20%, Mn < 0.20%, P < 0.025%, S: 0.008-0.012 percent of Mg, 0.035-0.045 percent of Mg;

step (5) pouring: controlling the pouring temperature to 1330-1370 ℃, and carrying out stream inoculation during pouring; and controlling the flow rate of the inner pouring gate, wherein the speed of the inner pouring gate is controlled to be less than 50cm/s in the whole pouring process.

Has the advantages that: the invention has simple operation, low cost and high efficiency, does not need to adopt a filter screen and a riser and only adopts a little chill. The surface of the casting is smooth, the polishing workload is small, the structure of the whole casting is relatively balanced, the difference is small, and the mechanical property is excellent.

Drawings

FIG. 1 is a schematic diagram of the metallographic structure of a reference block in the present invention;

FIG. 2 is a schematic representation of the metallographic structure of the cast body according to the invention.

Detailed Description

The present invention will be further described with reference to the following specific examples.

Detailed description of the preferred embodiment

A manufacturing method of a 2.8MW wind power hub comprises the following steps:

step (1), jolting and tamping during sand discharging, wherein the actual measurement of the tensile strength of the sand mold after resin sand solidification is 1.3 MPa;

step (1), a chill is placed at a boss part of a casting, the thickness of the boss part is 60-90mm, the thickness of the chill actually placed is 60mm, a phi 80 sprue is adopted as the sprue, and 6 phi 50 air outlets are placed at actual air outlets;

step (3), adopting high-purity pig iron and scrap steel, and controlling the total amount of trace impurity elements to be lower than 0.15%;

step (4), spheroidizing inoculation: 0.90% of nodulizer and 0.35% of inoculant for covering are sequentially added into the nodulizing ladle, and 35ppm of Sb is added during nodulizing; standing for 6 minutes after spheroidizing, and then removing slag. C in molten iron after spheroidizing treatment: 3.72%, Si: 2.09%, Mn: 0.15%, P: 0.020%, S: 0.008%, Mg: 0.037%;

step (5), controlling the pouring temperature to 1340 ℃, and carrying out stream inoculation during pouring; the actual mold filling time of the whole pouring process is 203s, and the average speed of the inner pouring gate in the pouring process is 31 cm/s.

Detailed description of the invention

A manufacturing method of a 2.8MW wind power hub comprises the following steps:

step (1), jolting and tamping during sand discharging, wherein the actual measurement of the tensile strength of the sand mold after resin sand solidification is 1.2 MPa;

step (1), a chill is placed at a boss part of a casting, the thickness of the boss part is 60-80mm, the thickness of the chill actually placed is 60mm, a phi 80 sprue is adopted as the sprue, and 5 phi 50 air outlets are placed at actual air outlets;

step (3), adopting high-purity pig iron and scrap steel, and controlling the total amount of trace impurity elements to be lower than 0.15%;

step (4), spheroidizing inoculation: 0.85 percent of nodulizer and 0.45 percent of inoculant for covering are sequentially added into the nodulizing ladle, and 40ppm of Sb is added during nodulizing; standing for 8 minutes after spheroidizing, and then removing slag. C in molten iron after spheroidizing treatment: 3.69%, Si: 2.10%, Mn: 0.13%, P: 0.021%, S: 0.009%, Mg: 0.039%;

step (5), controlling the pouring temperature to be 1345 ℃, and carrying out stream inoculation during pouring; the actual mold filling time of the whole pouring process is 220s, and the average speed of an inner pouring gate in the pouring process is 29 cm/s.

Detailed description of the preferred embodiment

A manufacturing method of a 2.8MW wind power hub comprises the following steps:

step (1), jolting and tamping during sand discharging, wherein the actual measurement of the tensile strength of the sand mold after resin sand solidification is 1.4 MPa;

step (1), a chill is placed at a boss part of a casting, the thickness of the boss part is 60-80mm, the thickness of the chill actually placed is 60mm, a phi 80 sprue is adopted as the sprue, and 5 phi 50 air outlets are placed at actual air outlets;

step (3), adopting high-purity pig iron and scrap steel, and controlling the total amount of trace impurity elements to be lower than 0.15%;

step (4), spheroidizing inoculation: 0.90% of nodulizer and 0.40% of inoculant for covering are sequentially added into the nodulizing ladle, and 45ppm of Sb is added during nodulizing; standing for 8 minutes after spheroidizing, and then removing slag. C in molten iron after spheroidizing treatment: 3.75%, Si: 2.05%, Mn: 0.14%, P: 0.022%, S: 0.010%, Mg: 0.040%;

step (5), controlling the pouring temperature to be 1360 ℃, and carrying out stream inoculation during pouring; the actual mold filling time of the whole pouring process is 210s, and the average speed of the inner gate of the pouring process is 30 cm/s.

The size of the test block to be annotated in the invention adopts a non-standard test block of 150 × 170, and the mechanical properties are as follows: tensile strength 378MPa, yield strength 246MPa, elongation 22 percent and V-notch impact at-30 ℃ of 14.5J. The schematic diagram of the metallographic structure is shown in figure 1: pearlite is less than 5 percent, the spheroidization ratio is more than 90 percent, and the size of graphite spheres is 5-6 grades.

The mechanical properties of the cast main shaft flange body are as follows: the tensile strength is 365MPa, the yield strength is 237MPa, the elongation is 16 percent, and the V-shaped notch impact is 12J at the temperature of minus 30 ℃. The metallographic structure of the body is schematically shown in figure 2: pearlite is less than 5 percent, the spheroidization ratio is more than 90 percent, and the graphite spheres are 5-6 grade in size and impact is 12J at the temperature of minus 30 ℃.

The preparation method is simple, the operation is simple and convenient, the efficiency is high, a filter screen and a riser are not needed, and only a small amount of chilling blocks are used. The internal structure of the casting is compact, the ultrasonic flaw detection and the magnetic particle flaw detection meet the requirements, the surface of the casting is smooth and clean, the polishing workload is small, the structure of the whole casting is relatively balanced, the difference is small, and the mechanical property of the whole casting is excellent.

The present invention is not limited to the above-mentioned preferred embodiments, and any other products in various forms can be obtained by anyone in the light of the present invention, but any changes in the shape or structure thereof, which have the same or similar technical solutions as those of the present application, fall within the protection scope of the present invention.

Claims (1)

1. A manufacturing method of a 2.8MW wind power hub is characterized by comprising the following steps: the method comprises the following steps:

step (1), sand releasing: jolting and tamping when releasing sand, controlling the tensile strength of the sand mould, wherein the tensile strength of the sand mould after the resin sand is solidified is more than or equal to 1.2 Mpa;

step (2), placing a proper chiller at the boss position of the casting and selecting a proper air outlet area: a chill is placed at the boss part of the casting, the thickness of the chill is 0.5-1 time of that of the boss, and the gas outlet area is more than 1.5 times of that of the sprue;

step (3), smelting: smelting by adopting high-purity pig iron and scrap steel, and controlling the total content of trace impurity elements to be lower than 0.15%;

step (4), spheroidizing inoculation: 0.8-1.0% of nodulizer and 0.3-0.6% of inoculant for covering are sequentially added into the nodulizing ladle, and 30-80ppm of Sb is added during nodulizing; standing for 5-10 minutes after spheroidizing and then slagging; c in molten iron after spheroidizing treatment: 3.65-3.75%, Si: 2.0-2.20%, Mn < 0.20%, P < 0.025%, S: 0.008-0.012 percent of Mg, 0.035-0.045 percent of Mg;

step (5) pouring: controlling the pouring temperature to 1330-1370 ℃, and carrying out stream inoculation during pouring; and controlling the flow rate of the inner pouring gate, wherein the speed of the inner pouring gate is controlled to be less than 50cm/s in the whole pouring process.

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