Explan: Detailed introduction to spur gear casting ladle transmission and self-locking principles, contains traditional worm gear ladle.
Detailed instruction of spur gear foundry ladles
and worm wheel ladles
Spur gear foundry ladle: The hand wheel is driven by the spur gear. The hand chain hoist brake is locked and opened unconsciously and rotate to pour molten iron. It features easy operation, low wearing and no “head collision”. The gear of hand chain hoist, no bad. At you aligning to the pouring gate, if the ladle lift its head, your force is smaller than the worm wheel. Some spur gear foundry ladle has been used for more than ten years.
Traditional worm gear ladle is inefficient. After use, it creates wear and collision. If the wear is sharp, the gear will break and accident.
CLC number: TG232.7； Reference identification code: B； articlenumber: 1006—9658(2017)02—0069—02
DOI：10.3969/j.issn.1006—9658.2017.02.023
中图分类号：TG232.7；文献标识码：B；文章编号：1006—9658(2017)02—0069—02
丁衍德.直齿轮铁液包与传统铁液包介绍[J].中国铸造装备与技术.2017(02).
1 Gravity center of foundry ladle and its axis of rotation
The ladle lining and the iron plate form an empty foundry ladle center of gravity; the rated molten iron plus the empty ladle constitutes a full-pack synthetic center of gravity. Determine where one position of the ladle is the rotating shaft, weld the ladle shaft; this shaft is fitted with gears through the bearing holes below the boom.
Figure 1 Diagram of gravity center and axle center of molten iron ladle.
1. Axle center of safe spur gear ladle; 2 Rated molten iron and empty ladle and composite gravity center; 3 Axle center of portable worm wheel ladle; 4 Axle center of portable spur gear ladle; 5 Gravity center of empty molten iron ladle.
1.1 Safe ladle:
The center of the rotary shaft is higher than empty molten iron ladle center and it of the composite gravity center of the full ladle. For example, the shaft of a safety spur gear ladle, like a water bucket sling, it has a high axis. When pour water out, for the position of the shaft, the weight always wants the vertical its body; when the self-locking fails, the molten iron will not flow out. Such a ladle is called a safety ladle.
The torque, which is caused by the gravity center of the ladle body, and makes the foundry ladle body vertical, is called as the positive force torque. The dumping torque caused by the gravity of the cast ladle is called negative torque.
Facing the reducer of the ladle, generally the molten iron is cast anticlockwise. Assume that the teeth above the shaft centergear bears the force, like the position of 12:00 time of a clock. To rotate the hand wheel, the right side of the up gear will bear the force anticlockwise. The gravity of the ladle always keeps the ladle vertical, so the tooth face will bear the force anticlockwise during whole casting. The gear teeth will continuously transmit without jittering. One direction of the reducer, one brake can be self-locking, it will not appear "collision" phenomenon.
It has a large operating force and the worm wheel ladle is inefficient, so the safety shaft is not used. The efficiency of the gear is high, the small straight gear ladle uses a safety ladle, and the operating force is not increased much.
1.2 Portable ladle
The axis of the rotating shaft is selected below the center of gravity of the full ladle, and the center of gravity of the empty ladle is above; it has a small operating force and is called a portable ladle. Both the conventional worm gear ladle and the large and medium sized spur gear ladle use this axis.
Casting ladle collision problem: When the portable ladle is poured with molten iron, facing the reducer of the package body, it is customary to cast castings counterclockwise. When the hand wheel is rotated to move away from the vertical position, the right side above the shaft center gear will bear the force anticlockwise. After the ladle leaves the vertical surface, synthetic gravity center of ladle full of molten iron, and its gravity itself wants to dump. So, the package quickly enters another meshing tooth its opposite tooth surface position, the ladle collides forward. (When the gear wear is thin and the gap is large, the "collision" phenomenon is very powerful) The left side of the above tooth face will bear the force clockwise, the self-locking force of the reducer acts as a balance. The gear of the ladle shaft rotates counterclockwise, and continues to cast molten iron.
Figure 2 Diagram of “head collision” caused by gap.
1. Gear or worm gear on the shaft of the ladle; 2. Meshing gear or rack of worm cross section; 3. After wear, the weight of full ladle causes it to dump, and the other meshing teeth resist; 4. The ladle shaft gear is not worn, the reverse tooth surface; 5. Leaving the vertical position, the ladle shaft gear is stressed; 6. Actual tooth surface position of the meshing teeth after wear; 7. Leaving the vertical position, the wear gear is stressed.
In the later stage of pouring, the molten iron is slowly decreasing, and the actual center of gravity drops below the axis of rotation; you should push it counterclockwise to continue pouring the molten iron. The center of gravity of the original ladle, the dumping force caused by gravity, has now become a vertical force. The left side of the tooth above the ladle shaft gear retreats to the right side of the upper tooth. It is counter-clockwise force. The body quickly retreats to another meshing tooth, and its tooth surface position in the opposite direction. Due to the gap between the gears, so the body will "collide" backwards. If the installation and wear gaps are large, the "collision" phenomenon will be severe.
1.3 Empty ladle
Regardless of the safety ladle or the portable ladle, the axis of the rotating shaft is higher than the center of gravity of the empty ladle. The empty ladle is the same as the safety ladle. The teeth above the ladle shaft gear are stressed in one direction, and it is no “collision” phenomenon.
2 spur gear self-locking foundry ladle
The spur gear self-locking foundry ladle (called as the spur gear ladle). The self-locking of the ladle uses hand chain hoist-type screw load brake, which can self-lock and open without knowing it. The ratchets, pawls and friction plates in the brakes are standard parts of the hand chain hoist. The spur gear drive is similar to rolling friction, and has an efficiency of 97%. It is easy to install and wears less, it is widely used.
2.1 Small spur gear safety ladle
The high-axis safety does not appear “collision” phenomenon, and the safety shaft is good when the operating force is not large; People are used to pouring molten iron in one direction, and a small spur gear ladle is equipped with one brake secondary gear transmission. Because it is self-locking in one direction, it can cast molten iron according to your habits, and there will be no "collision" phenomenon. When turning in the other direction, there is no self-locking; therefore, only one pouring spout is provided to prevent misoperation. The user has considered individual circumstances, it can also add a pouring spout.
Figure 3: Hand chain hoist
Figure 4: Spur gear small foundry ladle
2.2 Large and medium sized spur gear portable ladle
The large and medium-sized spur gear portable ladle is equipped with two brakes, which can be automatically converted, and the dumping and vertical moments can be self-locking. The spur gear has a small gap, less rolling friction and wear, and there is basically no "collision" phenomenon. The friction plates wear gap is adjustable. In order to prevent the brake from working unreasonably, only one pouring spout is provided. User requirements, do two pouring spout can also be. The large spur gear ladle can be used without the motor cable, and it works by hand.
2.3 Precautions
The brakes of the spur gear ladle and the hand chain hoist are the same, it borrows your strength to fight your strength, and the greater the torque, the greater the self-locking force. When the empty ladle and torque are small, the self-locking force is small, please note that the force is small and unstable. At this time, do not leave the initiative location, do not leave the hand wheel; if you pull the suspender or the boom, it will break the self-locking and easily lead to accidents.
2.4 Actual use
At present, 0.5t, 1t, 2t, 5t spur gear ladle has been used, and some products have been used for more than ten years. The spur gear ladle is self-locking and opening, no crevice; the gear is not broken, and the friction plate is rarely replaced. I drew 10t and 20t drawings, which can throw away the big plait in the casting environment - the motor cable. Spur gear ladle is designed according to Chinese national standard, GB/T25714-2010 Standard: ladle's iron and lining and technical conditions, and the package body is produced according to JBT 5771-1991 iron melt ladle parameters. The load-bearing sling is a forging, the lower platform and sling body below are integral forgings. Bearing hole under the boom, it is a processed of the inner surface after welding.
Figure 5 Spur gear small foundry ladle reducer:
① foundry ladle shaft; ② pawl; ③ ratchet wheel; ④friction plate; ⑤ nut hand-wheel.
3 Traditional worm casting ladle
3.1 Traditional worm casting ladle
Traditional worm gear foundry ladle (referred to as worm gear ladle). Its flip mechanism is generally a worm gear plus a bevel gear steering; there are also secondary worm gear drives. The large cast ladle is electric. The worm gear has a large transmission ratio and self-locking characteristics, so it is widely used.
Figure 6: Traditional worm wheel foundry ladle reducer① bevel gear; ② hand wheel; ③ foundry ladle shaft; ④ worm wheel.
3.2 Weaknesses of the worm wheel ladle
The worm gear is mechanically inefficient, manual operation, it requires a lot of operating force. Involving worm gears, worms, bevel gears, their perpendicularity and intersection, so the installation is difficult; If the gap is big, “head collision” will occur. The worm rotates one turn, and the worm wheel is turned by one tooth, and the worm wheel is sliding friction. As the wear gap increases, the "collision" also increases. If the wear is sharp, the gear will break and accident. The worm wheel helix angle is smaller than the friction angle, and the worm wheel can be self-locking; so it has a large transmission ratio, low efficiency and high wear. Self-locking worm gears are less than 40% efficient, typically 30%.
If the furnace operates every day, Copper worm gear cannot be used for three years. It is troublesome to repair and replace the worm wheel.
4 Displacement casting of foundry ladle
Portable ladle reducer design, In the early and late stages of pouring, the maximum operating force is equal when pouring molten iron. Control the power of the worm, it is very different between passive and active, at it is passive it is small, but it is very big when it is initiative. When the ladle is ready to pour the second casting, prevent the molten iron from flowing out, and the ladle should be raised head, at this time, the worm must be initiative and its operating force is large. Control the spur gear, the difference is small when passive and initiative, and the spur gear ladle raises its head and its operating force is small.
At you aligning to the pouring gate, if the ladle needs to lift the head, the gear force is less than the worm wheel.
In both cases, you will also feel the spur gear ladles are easy to use.
5 Conclusions
Although the principle of hand chain hoist is not easy to explain, a spur gear ladle with the same structural principle, it works really well.
The United States has spur gear ladle, which indicates that the foundry ladle of the spur gear and brake are the development direction. Hand chain hoist of the spur gear and brake, which have eliminated worm gear cranes; the same spur gear ladles will replace the worm gear ladles. Spur gear ladle is more useful than worm gear ladle, and it will certainly be welcomed by the foundry ladle market.
Figure 7. American spur gear ladle reducer
Figure 8: American worm gear ladle
The development of spur gear ladle: Professor Meng Fanyu, who edited the textbooks of higher education, and editor-in-chief of Li Zhengzheng, [China foundry equipment and technology] magazine, they supported me. I am grateful for this.
Author DING Yande (1947—) www.d1947.com Senior engineer, has been engaged in mechanical design and manufacturing and process work.
References
[1] Dong Chao editor, Meng Fanyu topic. Design of casting equipment for college textbooks [M], topic 2 Design of cone-shaped bucket pouring ladle, Beijing: Mechanical Industry Press, 1980.
[1]董超主编，孟繁玉专题。高等学校试用教材铸造设备设计[M],专题二 锥桶形倾注式浇包设计，北京:机械工业出版社,1980。
[2] Ding Yande. Hand chain hoist spur gear self-locking ladle[J]. China foundry equipment and technology. 1998(05)
DOI: cnki: ISSN: 1006-9658.0.1998-05-007.
[2]. 丁衍德.手拉葫芦式直齿自锁浇包[J].中国铸造装备与技术.1998(05)
DOI: cnki:ISSN:1006-9658.0.1998-05-007.
Spur Gear Foundry Ladle can Replace Worm Wheel Ladle
The factory uses spur gear reducers, which have high transmission efficiency and low wear. Worm gear reducers are used in places where space is limited or where only signals are transmitted. It is low in efficiency and wears out.
Spur gear foundry ladle: The hand wheel is driven by the spur gear. The hand chain hoist brake is locked and opened unconsciously, and rotate to pour molten iron. It features easy operation, low wearing and no “head collision”. At you aligning to the pouring gate, if the ladle needs to lift the head, the gear force is less than the worm wheel. The pouring mechanism does not have a chain of chain hoists, and there is no climbing wheel phenomenon, which is more reliable than the hand chain hoist.
The spur gear efficiency is 97%. The brakes are made of hand chain hoist standard parts and can be replaced. The small spur gear ladle uses a safe shaft and one brake controls the vertical moment. There is no collision at all. The medium-sized spur gear ladle adopts a portable shaft, and the two brakes respectively control the vertical moment dumping moment. The collision is very light, and wear can compensate. Due to high efficiency, large straight gear ladle does not use motor cable, just by hand, we removed the big braid of the worm gear ladle.
Self-locking worm gear efficiency is 30%. The new worm gear ladle collision is light, after using the wear the collision is amazing. The teeth of the gear are severely worn and easily broken and accidents. When the ladle needs to lift the head, the force is large. If the furnace operates every day, Copper worm gear cannot be used for three years; the worm gear of ductile iron has to change one in a year.
US advertising shows the US spur gear ladle. Its structure is unreasonable, but it represents the spur gear ladle and is the future development trend. Hand chain hoist of the spur gear and brake, which have eliminated worm gear cranes; the same, spur gear ladles will replace the traditional worm gear ladles. A hexagonal pencil is a little better than a round pencil, and it can capture the round pencil market.
Spur gear ladle is better than worm gear ladle, so workers are willing to use it. It is listed in the list of China's foundry machinery products and will certainly be welcomed by the foundry ladles market.
Spur Gear Foundry Ladle and Hand Chain Hoist
Hand pull the sprocket nut, through the screw load brake, straight gear transmission deceleration and torque increase; drive the lifting sprocket, directly or by moving the pulley, pull up the heavy object. This brake has good self-locking ability and can be locked and opened without knowing it, and it can operate freely.
Hand chain hoist. Pull it, the weight will rise, if you don't pull it will stop and lock itself. you pull it again and continue to rise. You pull on the other side, it will be lowered, if you don't pull it will stop and lock, you pull it and continue to descend, it operates freely. It is widely used, it is used everywhere. Old worm gear cranes were eliminated due to their low efficiency and easy wear.
When the hand chain hoist was trial-produced in Tai'an, Shandong, it was called the god of gourd. The principle of this brake is difficult to describe, and it is not described in the new mechanical design manuals. It can only understand the meaning, it is not easy to explain in words.
Hand chain hoist
Small spur gear ladle
①foundry ladle shaft; ②pawl; ③ratchet wheel
④friction plate; ⑤nut hand-wheel
The hand chain hoist and spur gear small ladle and empty ladle are the same: the chain sprocket nut of the hand chain hoist is equal to the nut hand-wheel of the ladle; the weight of the hand chain hoist is equal to the vertical moment of the safety ladle and the empty ladle.
Facing the hand chain hoist, hand pull the thin chain and turn it clockwise, the sprocket nut clamps the friction plate and the ratchet, rotating clockwise together (the pawl allows clockwise rotation); By gear reduction and torque increase, the driving lift sprocket is rotated clockwise to lift heavy objects. If the hand does not move, the weight is attempting to fall and rotate counterclockwise; the ratchet friction plate clamped in front has been integrated, the pawl blocks its counterclockwise rotation. Hand does not move and it automatically locks. Pull the chain again and turn it clockwise, same, the weight will be lifted again.
Pull the thin chain on the other side, the sprocket nut loosens the friction plate and the ratchet and rotates counterclockwise; when the heavy object falls, it passes through the gear and counterclockwise follows the sprocket nut; also tightened the friction plate and the ratchet; if you want to follow up again, the ratchet that has been clamped is blocked by the pawl (the pawl allows clockwise rotation and cannot counterclockwise); how much do you loose, how much it turns counterclockwise, it locks naturally. The ratchet friction plate and the gear shaft are dynamic fit, and the work is not contradictory. The hand stops pulling, and the weight clamps the ratchet friction plate counterclockwise, and the pawl blocks the ratchet and self-locks. Pull the other side of the chain again, turn counterclockwise, the weight falls; the gear ratchet normally follows, normal self-locking.
The self-locking of the spur gear casting ladle is the same as that of the hand chain hoist, use your own power to strike yourself. If the weight is heavier, it appears to be more self-locking, and the lock is stronger. Note: When the load is small or empty ladle, it is also self-locking; its self-locking force is small, it seems to be inadvertent.
You are interested, I can combine the real thing, and explain it carefully. Actual self-locking, it is locked and unlocked without knowing it; work smoothly, freedom of operation, you can try it yourself.
Worm Wheel
Foundry Ladles
Traditional worm gear foundry ladle (referred to as worm gear ladle). Its flip mechanism is generally a worm gear plus a bevel gear steering; there are also secondary worm gear drives. The large cast ladle is electric. The worm gear has a large transmission ratio and self-locking characteristics, so it is widely used.
The worm gear is mechanically inefficient, manual operation, it requires a lot of operating force. Involving worm gears, worms, bevel gears, their perpendicularity and intersection, so the installation is difficult; If the gap is big, “head collision” will occur. The worm rotates one turn, and the worm wheel is turned by one tooth, and the worm wheel is sliding friction. As the wear gap increases, the "collision" also increases. If the wear is sharp, the gear will break and accident. The worm wheel helix angle is smaller than the friction angle, and the worm wheel can be self-locking; so it has a large transmission ratio, low efficiency and high wear. Self-locking worm gears are less than 40% efficient, typically 30%.
If the furnace operates every day, Copper worm gear cannot be used for three years. The worm gear of ductile iron has to change one in a year. It is troublesome to repair and replace the worm wheel.