Design and application of special crane for pipe pile

2022-09-01

In recent years, China has accelerated the pace of machine substitution in the traditional production industry. It is indispensable to configure special cranes for pipe pile production in the process layout of concrete pipe pile production lines. The special crane for pipe pile production adopts the form of double-beam double-car bridge crane, and the automatic clamp lifting beam is suspended under the hook. For the characteristics of the working condition of the pipe pile production, the crane should meet the requirements of the working condition in the design.

I. Working conditions and technical parameters

The production of concrete pipe piles is generally uninterrupted production of three shifts. The noise and humidity of the production workshop are large, the ambient temperature of the steaming workshop is high, and the production efficiency of the assembly line is relatively high. Taking into account the efficiency factor, the crane driver is more eager to operate, often adopting the braking mode of the reverse running of the big car running mechanism, and the reliability of the equipment including the crane is high, no fault is allowed, and once the fault occurs, the whole production line It will be awkward. The versatility, safety reliability and service life requirements of the automatic clamps are relatively high. The usual pipe pile diameter is φ400~φ800mm, the length of the pipe pile is 10~15m, the pipe piles are more specifications, and the automatic clamp requires the production of common pipe piles of various specifications. . At the same time, the automatic clamp hoisting beam runs three-dimensionally with the crane in the workshop. It is required that the automatic fixture must be safe and reliable when moving the clamped pile mold. The automatic fixture should not be opened in the air to avoid accidents. The automatic fixture lifting beam should be able to accurately position the mold in the running direction of the cart. It is not allowed to automatically clamp the front and rear of the lifting beam when the cart is parked, which makes it difficult for the automatic fixture to quickly locate and clamp the mold. According to the characteristics of working conditions, the main technical parameters of the crane are: QE double-car bridge crane, the working level of the whole machine should be A7~A8, the operation mode is indoor operation, and the lifting weight can be selected according to the quality of “pipe pile + tube mold” 8t+ 8t, 10t+10t, 16t+16t, 20t+20t, lifting speed is 13~15m/min, car speed is 30~45m/min, and the speed of the cart is 110~120m/min. Figure 1 is a schematic diagram of a special crane for pipe pile production.

Second, design points

2.1 Lifting mechanism

When selecting the hoisting motor, the actual operating conditions of high ambient temperature, high humidity, and mechanical working level M7~M8 should be considered. The hoisting motor must be calculated by heat check. When selecting the hoist reducer, the characteristics of frequent starting and braking of the mechanism should be considered. The hardened gear reducer should be used. The radial load of the reducer, the input power of the high speed shaft and the output torque of the low speed shaft are at the working level M7~M8. Need to meet the requirements. Since the outer surface of the low-speed shaft end of the hard-tooth reducer is generally 42CrMo, the material of the inner ring of the reel engaged with the outer gear of the low-speed shaft end of the reducer should be matched with ZG42CrMo, and usually the crane is lifted in the reel. The toothed disc is made of ZG340-640. If the ZG340-640 is still used for the internal gear plate of the hoisting drum of the special pile crane production, the wear amount will exceed the normal value after the use, and a broken tooth accident will occur.

The hoisting brake is a safety device for the hoisting mechanism, and a single push rod hydraulic brake should be used. Since the special crane hook of the pipe pile production hangs the automatic clamp lifting beam, there is no no-load time period for the brake, so the working level of the lifting brake is higher. Considering the actual production of the pipe pile, the braking torque is higher than GB. The safety factor recommended by the /T 3811-2008 "Crane Design Code" is about 25% higher to meet the long-cycle trouble-free use of pipe pile production.

2.2 trolley operating mechanism

The special crane for pipe pile production adopts the form of double beam and double trolley. The arrangement distance of the two trolleys is fixed (the general spacing is 6~8m), so the trolley running mechanism is only used for small stroke adjustment (the general stroke is not more than 2m). ). It can be seen that the working level of the trolley running mechanism is only M4~M5, and it is not necessary to match or closely match the working level of the whole machine.

2.3 cart running mechanism

Due to the pursuit of production of pipe piles, crane maintenance personnel will generally relax the brakes of the vehicle running mechanism in actual work, and the crane driver uses the reverse operation to force the parking to achieve the purpose of instantaneous parking. However, this rough operation mode will cause great impact damage to the motor, reducer, wheel and other components of the vehicle running mechanism. Therefore, the following points should be noted when designing the running mechanism of the cart:

1) The power selection of the motor must meet the requirements of the working system of M8. The inverter motor is recommended to use the variable frequency motor. The operation of the variable frequency control cart can greatly improve the consequences of forced parking due to the reverse operation mode;

2) On the basis of satisfying the input power and output torque of the high-speed shaft, it is advisable to increase the diameter of the low-speed shaft of the reducer, the flat key and the bearing (the general load-bearing capacity needs to be increased by about 30%) to avoid the twisting of the reducer during use. An accident that breaks the low speed shaft;

3) The wheel set should also increase the diameter of the active wheel axle head and the flat key specifications, and improve the material grade of the wheel. The ZG340-640, which is usually used on the bridge machine, is changed to ZG50SiMn, and the wheel tread quenching is changed to the overall heat treatment. To improve the wear resistance and service life of the wheel.

2.4 Bridge

The bridge for the special production of pipe piles consists of two parallelly arranged main beams and two end beams respectively mounted on the sides of the cart tracks. When designing the main beam, because the lifting speed is relatively large, the hoisting load dynamic load coefficient is relatively large, and the fatigue strength of the main beam should be fully considered: because the running speed of the big car is fast, and there is a way of reverse running to force the parking. The bad habits should be strictly horizontal stiffness requirements: since the distance between the two cars is a fixed value, and the automatic clamp lifting beam is hung on the hook, the two cars do not have the problem of accidental closeness, so the car's own weight and lifting load Forced model calculations can be arranged at intervals.

Third, technological innovation

3.1 Innovative use of articulated sway arm

Generally, the running speed of the cart reaches 110~120m/min. If the automatic clamp is close to the tube mold, it will stop suddenly. The lifting beam will sway back and forth in the running direction of the cart, making it difficult for the automatic fixture to be quickly and accurately positioned. Shake the device. The anti-sway device adopts the swing arm form (see Fig. 2), and the upper end is connected with the lower frame through the bidirectional (the running direction of the cart and the lifting direction), and the lower end is connected with the connecting seat above the hanging beam through the pin shaft, which The design can not only meet the rapid and accurate positioning of the lifting beam, but also ensure the reliable and safe structure of the upper and lower hinge points. If there is no hinge structure in the running direction of the cart at the upper end of the swing arm, the upper end of the swing arm is subjected to the bending moment caused by the inertial force when the cart suddenly stops, causing the joint weld at the upper end of the swing arm to crack or the base material at the intersection of the welding stress. fracture.

3.2 Reasonable use of wheel brakes

Since the brakes of the running mechanism of the cart are relaxed at the time of shipment, the crane has no ability to automatically brake and stop when the power is off (for example, when the cart runs at high speed, it suddenly encounters a power outage or a power outage, because there is no big cart at this time. The role of the brake, the crane will directly hit the big vehicle stop at the end of the workshop under the action of inertia. This kind of accident will bring accidents to the safety production. Therefore, an electric wheel brake (normally closed) must be installed at the time of design, and the wheel brake automatically clamps the wheel of the cart once the power is turned off. The wheel brake acts as a safety device rather than a brake running mechanism. The electrical control of the wheel brake is related to whether the power supply of the whole machine is powered off, and has nothing to do with whether the running mechanism of the vehicle is operating. In the event of an unexpected power outage or power outage, the wheel brakes will hold the cart wheels and serve as a safe stop.

3.3 Innovative design of automatic fixtures required for the production of pipe piles

The automatic clamp lifting beam is suspended under the hook of the special crane for pipe pile production. According to the process arrangement of the pipe pile production, various automatic clamps are installed separately or in combination for each process.

1) Centrifugation and steaming process In the process layout, the centrifugation and steaming processes are in the same cross-floor workshop, and the card-type automatic fixture is arranged in this workshop. The length of the pipe pile is usually 15m or less. Four card clamps are used, and the length of the lifting beam is 10.5m, which can meet the lifting work required for centrifugal and steaming of various pipe piles of φ400~φ800mm. As shown in Figure 1, the card clamp can hold the mold to the running wheel of the upper cover mold, so as to carry the whole mold, open the upper cover mold or close the upper cover mold, respectively for lifting the mold to the centrifuge for centrifugation and After the centrifugation is completed, the mold is placed in the steaming tank to be steamed and steamed.

2) Card clamping is required for the mold opening, feeding and clamping process to start the mold and mold clamping process; the feeding process needs to carry the bottom mold of the pipe pile, and the holding clamp is required. Therefore, in order to meet the configuration requirements of the two different fixtures, the crane will be equipped with a card type + holding type combination clamp under the automatic clamp beam. When feeding, the steel cage should be placed in the lower bottom mold. Therefore, the steel cage clamp is added on the basis of the card type + hug combined clamp, and the automatic fixture designed as the "three-in-one of the card + hug + steel cage" function is designed. ,As shown in Figure 3.

3) The pile-out process After the cassette clamp is lifted and lifted, the vacuum clamp is used to lift the pile automatic clamp, and the concrete pile pile is lifted from the lower mold by the vacuum suction cup and transported to the designated stacking area. The schematic diagram of the automatic clamping of the vacuum suction cup is shown in Figure 4.

4) Design points of automatic fixture

The above-mentioned various types of automatic clamps are used in the process lines of the pipe pile production. The vacuum clamps are automatically clamped by the vacuum suction pump to drive the six vacuum suction cups to adsorb the surface of the concrete pipe pile, so that the pipe piles can be piled and transported from the lower bottom mold of the mold. . Considering the unevenness and safety of the suction cups, the safety redundancy factor of the vacuum suction cup suction is preferably not less than 2.5 times. Since the joint between the suction cup and the pipe pile surface is easy to wear after a certain period of use, it is recommended that the vacuum suction cup be tested every other month for the overload test of the suction pipe pile. If the result of the suction test cannot meet the safety redundancy factor twice The lower limit should be replaced with a new suction cup in time.

The other automatic fixtures use the compressed air of the air compressor to drive the telescopic movement of the cylinder to clamp or open the card or the hug. The air compressor is installed on the crane bridge platform and supplies air to the cylinder with a spring air pipe. The cylinders and the electronic valves that control the movement of the cylinders are generally installed in the hanging beam box. The card point or the hug design comes with a self-locking function (usually self-locking using the mechanical principle, the larger the vertical load of the clamp clamping, the larger the horizontal closing force of the clamp), and the sudden encounter when the lifting mold is off the ground Power failure, gas shutoff, air leakage or impact obstacles, misoperation will not open unexpectedly before laying down the mold, safe and reliable and high efficiency. The compressed air is environmentally friendly and pollution-free, and is easy to maintain.

Fourth, the use of effects

The usual pipe pile production adopts the double-span workshop circulating line as an automatic production line for pipe piles. The centrifugal and steaming workshops are equipped with two truck-type automatic clamp pipe pile production special cranes, and two sets of mold-opening piles and feeding mold-fixing workshops. "Card + hug + steel cage" three automatic clamp pipe pile production special crane and a vacuum suction cup pile crane. The above-mentioned automatic assembly line can realize the production of concrete pipe pile with an annual output of 600~800km, the degree of automation is very high, the labor arrangement is small, and the safety is significantly improved compared with the traditional production process.

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Application and Research of Pumping Concrete for PHC Piles

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