Xinyu Large Parts Co., Ltd Crane rental Through experience, we learned that there are many factors that affect the selection of lifting methods, and the customer does not know how to select the correct lifting method. Today, I summarized this problem for everyone:

(1) Nature of hoisting operation: new construction, expansion, continuation or reconstruction.

(2) Operation site: it refers to indoor operation or outdoor hoisting, whether the site is open or narrow, whether there are obstacles near the operation area that affect the hoisting operation, whether there are overhead pipelines, overhead concave convex power transmission lines, access travel conditions, the shape and ground endurance of the operation site, etc. in the operation space planning.

(3) Features of lifting objects: size, mass, shape (thin, tall, short or flat), and center of gravity.

(4) Quantity of lifting objects: single or multiple objects of the same specification, or multiple objects of adjacent specifications.

(5) Process method: select all hoisting or sectional hoisting or on-site single piece assembly; It is the forward installation method or the inverted installation method.

(6) Condition of machines and tools: new medium-sized lifting equipment is required; Existing shared lifting equipment; There are hoisting machines and tools that can be used after combination or modification; The required lifting equipment can be rented nearby.

(7) Personnel essence: the skill essence and hoisting skill status of engineering skilled personnel, commanding hoisting personnel and operators.

(8) Hoisting duration: the degree of mechanized hoisting is uneven, and the length of hoisting duration shall be selected.

(9) Economic effect: the hoisting cost is reasonable and the construction cost is normal.

(10) Safety and reliability: it is necessary to ensure the safety and reliability of the lifting operation and put safety first.

Selection principle of lifting method:

(1) The method shall be safe, reliable, scientific and reasonable.

(2) Try to advance mechanized lifting.

(3) Existing hoisting machinery and tools shall be fully used.

(4) Summarize various elements, draw up various lifting plans, compare with each other, and select the best one.

(5) Make a general evaluation on the construction period of the project and the hoisting cost, and select an outstanding plan with reasonable economy and normal construction period.

(6) Use all favorable conditions to promote scientific and advanced lifting plan.

Lifting method - lifting method and lifting appliance stress

According to the relative orientation and lifting methods of lifting tools and objects, the lifting methods can be roughly divided into the following 7 types, as shown in the figure below,

（1） Hanger orientation fixer

There are the following types of equipment orientation fixers:

(l) The appliance passes through the center of gravity of the lifting object. The center of gravity of the lifting appliance and the lifting object is on the same vertical line when lifting the lifting object, as shown in the following figure α As shown in, the reuse process of the object is stable, and the force on the spreader is equal to or slightly greater than the component of the object (because the influence of dynamic load must be considered).

(2) The lifting object lies flat, and the lifting appliance is hung at the center of one end of the lifting object. During the lifting process, one end of the lifting object touches the ground and the lifting appliance slightly violates the plumb condition due to its friction force, so that the force on the lifting appliance is more than half of the weight of the lifting object, and then the force on the lifting appliance gradually decreases. When the lifting object is quickly straightened, the force on the lifting appliance increases, and when it is completely lifted off the ground, the force on the lifting appliance is slightly greater than the weight of the lifting object, as shown in Figure b above.

(3) The lifting object lies flat, and the lifting appliance is lifted at the longitudinal center of a point above the center of gravity of the lifting object, as shown in Figure C above. During the lifting process, the force on the lifting appliance is far more than half of the weight of the lifting object, and the size of the force depends on the distance between the lifting point and the center of gravity of the lifting object. The smaller the spacing, the greater the force on the spreader, and vice versa. Then the force on the spreader gradually decreases. When the lifting object is about to be straightened, the force on the spreader increases. When it is completely lifted off the ground, the force on the spreader is slightly greater than the weight of the lifting object.

(4) The lifting object lies flat, and the lifting appliance is hung on a surrounding surface above the center of gravity of the lifting object, as shown in the above figure d. The force on the lifting appliance is similar to (3) during the lifting process, but if the deflection of the lifting appliance is slightly increased, the force is also slightly greater. When the lifting object is lifted off the ground, the lifting object is inclined, and its tilt angle is balanced when the lifting tool and the center of gravity of the lifting object coincide on a plumb line. This method needs to apply another force on the lifting object to reach the vertical position of the lifting object.

(5) The lifting object lies flat, the lifting tool is hung at one end of the lifting object, and the other end of the lifting object is connected to the fixed position, as shown in the above figure e. Use the wrench to make the lifting object rotate and stand straight. The force on the lifting appliance is far more than half of the weight of the lifting object, and it changes with the position of the lifting point. The higher the lifting point, the closer it is to the top of the dumpling joint, the smaller the force on the lifting appliance. Other, this lifting method has a large horizontal thrust on the dumpling joint when the lifting object just bends down and is lifted, and the thrust gradually decreases when the dumpling is lifted up and straightened.

（2） Lifting appliance azimuth mover

The lifting slings move in the following directions:

(1) The lifting object lies flat, and the lifting appliance is hoisted at the center of one end of the lifting object, as shown in the above figure f. When the lifting object is just hoisted, the force on the lifting appliance is half of the weight of the lifting object. As the lifting object is gradually straightened, the lifting appliance also moves with it, often insisting that the lifting appliance is vertical, and the force on the lifting appliance is also gradually reduced. This method can ensure that the lifting object is always in a stable state during the lifting process, and the force condition of the lifting appliance is also better than the method of fixing the lifting appliance. After the lifting object is straightened and lifted, the force on the lifting appliance is slightly greater than the weight of the lifting object.

(2) As shown in the figure g above, the lifting object lies flat, the lifting appliance stands obliquely above the lifting object, and the joint of the lifting appliance and the lifting object is a counter rotating shaft. Generally, the height of the lifting appliance should be greater than 1/3 of the length of the lifting object. If the height of the lifting appliance is larger, the lifting force will be reduced. In the process of pulling and hoisting, the relative orientation of the lifting object and the lifting appliance will not change, and a certain angle will be adhered to. Only the dumpling joint shaft will be used as the center of rotation. When the lifting object is pulled to a certain point of view, the ground anchor of the lifting rope will be in line with the lifting point, and the lifting appliance will complete the lifting function, and the lifting object will be pulled up and straightened by the lifting rope under continuous force.

(3) The second method of pulling and lifting is the double rotation method. The difference between this method and the above-mentioned pulling and lifting method is that the lifting object and the lifting appliance do not share a joint reversing point, and the lifting appliance reversing point moves an interval in the direction of the lifting point. This method can properly reduce the height of the lifting appliance and reduce the force on the lifting appliance.

Lifting method - lifting point and its selection

Requirements for selecting points:

(1) Generally, the point of use should be above the center of gravity of the lifting piece;

(2) The position of the selected lifting point shall ensure the stability and balance of the lifting piece;

(3) If the equipment has been provided with a lifting point, it should be used. Generally, it is not allowed to set another lifting point;

(4) The position of the selected lifting point shall ensure that plastic deformation will not be caused by the dead weight of the lifting piece;

(5) When selecting the point of use, try to avoid the finishing surface of the equipment;

(6) In the lifting process of lifting parts, the lifting points that are changed by force should be planned according to their great force

(7) When using the multiple lifting points method to lift slender lifting pieces, balance pulleys and other equipment shall be set between lifting points to ensure automatic balance between lifting points;

(8) It can only be used after admitting that the existing lifting lugs, hooks, eyelets and eyebolts on the equipment are set for all lifting equipment, or for lifting parts or only for lifting parts.

Hoisting method - the method of tying the sling at the lifting point

All crane rental customers in Huai'an shall select the lifting method and the method of binding the sling at the lifting point according to the shape characteristics, weight, effective lifting lugs and lifting purpose of the lifting pieces.

If the equipment has its own lifting lug, the connection between the lifting lug and the sling can be ended by hanging the sling directly on the lifting lug, connecting the sling and the lifting lug through the shackle, and hanging the sling on the lifting lug with round steel according to the type of lifting lug. For the lifting of element ear, the following common lifting methods and sling binding methods are listed.

（1） Hoisting of shaft and root parts composed of cylinder

This kind of parts are generally used as lifting lugs, which need to be hoisted by means of slings.

Two slings are tied to the rough machined surface at both ends of the shaft, and the angle between the sling and the horizontal is α Generally, it shall be greater than 45 °. The two slings are looped on the cylinder surface, and the two slings should be evenly arranged at both ends of the center of gravity. The spacing b between them should be appropriate. After lifting, the two slings will not slide close to each other again, and the lifting pieces can be kept stable. Two slings shall be of equal length, and their included angle with the horizontal α Generally, it shall be above 60 °.