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Development and Application of New Type Feeding Spheroidizing Station

Development and Application of New Type Feeding Spheroidizing Station

(Summary description)

Development and Application of New Type Feeding Spheroidizing Station


Liao Zhijin, Zhu Fusheng, Yang Qing, Zhong Weichang


(Longnan Longyttrium Heavy Rare Earth Technology Co., Ltd., Ganzhou, Jiangxi 341700)


Abstract: The newly developed wire feeding spheroidizing station is composed of cored wire and cored wire rack, wire inlet cage, wire feeding machine, wire outlet duct, wire feeding platform, environmental protection cover and its control system. Through the well-designed and manufactured wire feeding spheroidizing station, the transmission and feeding of the cored wire can be effectively realized, making the entire wire feeding process smoother; the installation of the wire feeding platform at the job site is convenient, the operability is high and the process applicability is good; The combined use of the environmental protection cover and the dust collector system can effectively eliminate the smoke and dust generated during spheroidization and improve environmental protection efficiency.
Keywords: new feeding line spheroidizing station; cored line; feeding line platform; environmental protection cover; dust removal system

Foreign countries put the ladle feeding technology into application in 1975. my country successfully developed the feeding technology and incorporated it into the refining process in the 1990s. Feeding technology is to crush various smelting additives (deoxidizers, desulfurizers, modifiers, alloys, etc.) into particles of a certain size (usually below 2 mm), and wrap them with cold-rolled low carbon steel strips. For the core wire, a predetermined length of cored wire is passed through the slag layer at a certain speed with the help of a wire feeding machine. As the outer steel strip of the cored wire continues to melt, the additives wrapped by it quickly melt and enter the molten steel [1]. Since the reaction between the added smelting additives and the molten metal is carried out inside the molten metal, the alloy elements can be prevented from being oxidized and burned by the air and the slag; and because this reaction is performed in the molten liquid with a certain static pressure head It is carried out deep, so that there is a larger contact area and longer reaction time between the additive or its vapor and the metal to be treated, so the various reactions inside the molten metal proceed more fully. Compared with other refining treatment methods, the wire feeding technology has the following
Advantages: ①High alloy yield and low amount of additives; ②Accurate amount of alloy added, good reproducibility of results; ③Easy to realize mechanization or automation of processing operations [2]; ④From the perspective of environmental improvement, adopt wire feeding technology for processing When molten iron is used, the amount of flue gas produced is less than that of the old technology, which is beneficial to improving the working environment [3]; ⑤From the perspective of labor intensity, the use of thread feeding method can reduce the labor intensity of workers receiving and weighing additives [ 4]. 1 Feeding line spheroidizing station Feeding line spheroidizing station is mainly composed of cored wire and cored wire rack, wire inlet cage, wire feeding machine, wire outlet conduit, wire feeding platform, covering part and its control system (see Figure 1) , Its on-site usage is shown in Figure 2. 2 Design and function of each component
2.1 Core-spun wire and core-spun wire rack
When using the cored wire, the main way of drawing the wire is from the inner circle. Therefore, after unpacking the outer package, in order to prevent the cored wire from being loosened and the cored wire is broken, confused, and drawn out multiple turns during the drawing, it is necessary to The cored wire is placed in the cored wire rack, and the cored wire rack is set. As shown in Figure 3, it is mainly composed of an arc-shaped top frame, a plurality of supporting rods, an adjusting nut, a bottom frame frame and a footing. The role of the bottom frame is to support and fork during transportation. The role of the support rod is to prevent the cored wire from loosening and support the top frame. The inner ring of the top frame is distributed in an arc shape, and the minor axis is smaller than the inner ring of the cored wire. The long axis is not smaller than the outer ring of the cored wire. When the cored wire is pulled out, the cored wire slides along the outlet hole, the cored wire will not be broken, and the wire will enter smoothly.
2.2 Inlet cage
The main function of the wire inlet cage is to separate the cored wires, introduce them into the wire feeding machine, straighten the curved core wires, and prevent them from breaking. As shown in Figure 4, the wire inlet cage is composed of a circular arc tube, a circular ring, a reinforcing rib, a support rod, and a plurality of circular rings with decreasing diameters. When in use, the cored wire enters from the end with the larger diameter and from the smaller diameter. One end comes out and enters the thread feeding machine smoothly. According to the actual production, the radius r of the arc-shaped round pipe is between 760 and 1 200 mm, which is the most convenient for production and use. If r is less than 700 mm, the cored wire will be easily damaged when it is removed; if r is greater than 1,200 mm, it will occupy more space and be inconvenient to thread.

2.3 Feeding machine
The thread feeding machine is the main part of the thread feeding station. Since the foundry shop site is usually dusty and the temperature is high, the selection of the wire feeding machine must consider the convenience of operation and use such as threading, as well as the ease of maintenance and the application of the field environment. The wire feeding machine shown in Figure 5 is mainly composed of a chassis, a driving device, a clamping device, and a wire inlet pipe and a wire outlet pipe [5]; the driving device is composed of two sets of the same geared motor with a motor, and the wire feeding drive wheel Installed on the output shaft of the reducer, the clamping device is composed of an air cylinder, two sets of "L" type pressure plates and two driven wheels. When working, first pass the cored wire from the wire inlet pipe into the chassis, and pass it through the wire feeding drive wheel and the driven gear to the wire outlet bend pipe. Start the motor with reducer and ventilate the cylinder in the positive direction. The cylinder drives the "L" type pressure plate to rotate and open around the supporting shaft, so that the driven gear is close to the driving wheel, and the cored wire is clamped to make the cored wire happen. The tooth shape changes, the driving wheel, the cored wire, and the driven wheel form a meshing movement, and the cored wire is forwarded to realize the wire feeding. If the air cylinder is ventilated in the opposite direction, the "L"-shaped pressure plate will contract around the fixed pin, and the driven wheel will leave the driving wheel [6].
2.4 Outlet conduit
The function of the outlet conduit is to guide the cored wire and vertically enter the center of the spheroidizing bag. After the cored wire passes through the wire feeding machine, it is usually straightened and squashed. Therefore, the outlet conduit needs to be designed in an arc shape so that the movement trajectory of the cored wire has no obvious corners, so that the entire wire feeding process is smooth and effective Reduce the occurrence of jamming and broken line faults. The radius of the arc-shaped outlet conduit is between 1 500-2 300 mm, and the outlet is the most smooth. If the radius is less than 1,000 mm, it is easy to produce a broken line phenomenon. At the same time, the incident angle of the cored wire should be kept as vertical as possible at the beginning of the feeding [7 ].

 
 
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2.5 Environmental protection cover
Due to the exhaust gas and dust generated during the spheroidization reaction, in order to meet the national requirements for environmental protection and improve the working environment of workers, an environmental protection cover is designed, which is composed of a cover, a box-type smoke collection cover, and a smoke exhaust pipe, all of which are welded by steel plates. The bottom of the cover is made of refractory materials, and there is a hole for smoke and dust in the middle; the upper part of the cover is opened with vents to facilitate the drainage of water in the refractory and prevent the refractory from cracking (see Figure 7). The environmental protection cover is suspended under the wire feeding platform by a cable chain. One end of the smoke exhaust pipe is installed on the box-type smoke and dust collection cover, and the installation direction of the smoke exhaust pipe can be adjusted according to the site; the other end is set in the main dust removal air pipe, so it can be used as A certain range of swing, so that when the spheroidizing bag enters the feeding station, if it collides with the environmental protection bag cover, it can play a buffering role. When feeding the thread, the spheroidizing bag and the environmental protection cover are tightly closed, the smoke and dust generated during the thread feeding can be effectively collected, and the energy consumption of collecting the smoke and dust is small.

2.6 Feeding platform
The wire feeding platform not only installs the wire feeding machine, the wire inlet cage, the wire outlet conduit, and the environmental protection cover, but also prevents the molten iron from splashing during the spheroidization reaction. Therefore, its strength and safety must be considered in the design and manufacture. After production, railings and skirting boards must be made according to the requirements of GB 4053.3-2009 "Safety Requirements for Fixed Steel Ladder and Platform Part 3: Industrial Protective Railings and Steel Platforms", according to GB 4053.1-2009 "Safety Requirements for Fixed Steel Ladder and Platforms" Part 1: Steel Straight Ladder" or GB 4053.2-2009 "Safety Requirements for Fixed Steel Ladder and Platform Part 2: Steel Inclined Ladder" requires building.

2.7 Control system
The control system is mainly composed of power distribution cabinet, touch screen, PLC, frequency converter, buttons, and counting device. Considering the environment where the dust is relatively large and the actual working time is short, the cabinet of the power distribution cabinet needs to be dust-proof. The counting device is installed in the thread feeding machine, on the side of the driven wheel, and plays the role of measuring the length of the thread. The touch screen, PLC, frequency converter, and keys are all installed in the power distribution cabinet, and the touch screen has the functions of reading, setting feeding parameters and storing production records; PLC is the core part of the entire control system, mainly for calculation and control functions ;According to the set parameters, and the weight of the molten iron input, calculate the feeding length, withdrawal length, and feeding speed; receive the feedback signal from the counting device, compare with the calculated theoretical length, and determine the running feeding and withdrawal ; By controlling the frequency converter and the solenoid valve of the cylinder, the start and stop of the motor of the wire feeder, the forward and reverse rotation, and the forward or reverse ventilation of the cylinder are controlled to realize the feeding and retreating functions.


3 Dust removal system
3.1 Selection of dust collector
When the wire is spheroidized, a large amount of smoke and dust will be generated. Its main components are magnesium oxide, iron oxide, and silicon oxide. Its dispersion is large (the particle size is larger than 10 μm, and some are below several microns), and the temperature is high. . In order to prevent secondary pollution, a cyclone dust collector combined with a bag filter is used for dry treatment, and a cyclone dust collector is used for primary dust removal to remove large particles of dust, and then enter the bag filter to process the particle size below a few microns Of dust. The cloth bag of the bag filter shall be made of high temperature resistant coated cloth bag.

3.2 Processing air volume
Because the environmental protection bag cover and the spheroidizing bag are tightly closed, the required air volume is small, but considering that the maximum temperature of the bag of the bag filter is less than 300 ℃, it is necessary to introduce a large amount of cold air and enter the bag filter after cooling.

 
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Generally, the air volume at the upper part of the airtight cover is calculated according to formula (1) [8]:
Q=3 600 f·VJ (1)
=3 600 f×0.5 =1 800 f
Measured by introducing 4 times the cold air, the total air volume is:
Q=5×1 800 f =9 000 f (2)
In the traditional rush-in method, in order to improve the dust suction effect, it is usually made into a dust suction hood in the form of a fume hood, and the air volume is calculated according to formula (2) [8]:
Q=22 745F' (3)
In formulas (1)-(3): Q is the exhaust air volume, m3/h; f is the section area of ​​the airtight cover, m2; VJ is the average wind speed perpendicular to the airtight cover, m/s, generally VJ=0.25~0.5 m /s; F'is the area of ​​the frame door, m2. The value of formula (2) is much smaller than the value of formula (3). It can be seen that the dust suction air volume required by the thread feeding technology is much smaller than that of the traditional flushing method

4 Conclusion
The new wire feeding spheroidizing station is composed of cored wire and cored wire rack, wire feeding cage, wire feeding machine, wire outlet conduit, wire feeding platform, covering part and its control system. The removable core-spun wire rack in the inner ring can effectively avoid the situation that the core-spun wire is loose and the core-spun wire is broken, confused, and drawn out multiple turns after the outer package is opened. The wire inlet cage is composed of a circular arc tube, a circular ring, a reinforcing rib, a support rod, and a plurality of circular rings with decreasing diameters. When in use, the cored wire enters from the end with the larger diameter and exits from the end with the smaller diameter for smooth entry Feeding machine. The split-layer wire feeding machine makes the cored wire pass from the wire inlet duct into the chassis, and pass through the wire feeding driving wheel and the driven gear to the outlet bend duct, so that the core wire is deformed in tooth shape, the driving wheel and the bag A meshing movement is formed between the core wire and the driven wheel, and the core wire is forwarded to realize the wire feeding. The outlet conduit needs to be designed in an arc shape, so that the movement trajectory of the cored wire has no obvious corners, so that the entire wire feeding process is smooth, and can effectively reduce the occurrence of jams and broken wires. The line feeding platform is made in accordance with relevant national standards, and it is easy to install on the job site, has good applicability, and can ensure the stable operation of the equipment. Through the combined use of the environmental protection cover and the dust collector system, the smoke and dust generated during the spheroidization process can be effectively collected and discharged, and the energy consumption of collecting the smoke and dust is small.

references:
[1] Xu Luming. Core-spun wire technology and its application in metallurgical industry [J]. Ferroalloy, 2008 (1): 30-33.
[2] Tan Feng, Wang Limin. Common faults and solutions for wire wrapping machines and wire feeding machines [J]. Heilongjiang Metallurgy, 2015, 35 (2): 42-44.
[3] Zhang Jun, Jie Geqi, Quan Guoying, et al. Application of wire-feeding spheroidization process in ductile iron production line [J]. Foundry, 2019, 68(2): 128-131.
[4] Wu Hesheng, Wu Yubin, Meng Shaoliang. Production of ductile iron with high magnesium alloy cored wire [J]. Foundry, 1999 (8): 33-34.
[5] Liao Zhijin, Yang Qing, Wen Zhihua, etc. A split-layer cored wire joining device: ZL201610020878.0 [P]. 2016-08-31.
[6] Liao Zhijin, Zhu Fusheng, Yang Qing, etc. Single-motor driven dual-stream cored wire joining device: ZL201620031728.5 [P]. 2016-05-25.
[7] Wang Xiu, Wu Binghuan, Chen Shenghua. Development and application of wire feeding spheroidizing process in ductile iron casting production line [J]. Foundry, 2010, 59 (11): 84-88.
[8] Wang Kun. Several problems in the design of vacuum hood [J]. Cement, 1997 (11): 21-23.

 

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