Grapple goat crane

Contents

Contents

1. Introduction of ______________________________________________________

2. Analytical overview of ____________________________________________

3. Research Section ________________________________________

4. Design Section _________________________________________

4.1. Calculation of lifting mechanism ___________________________________

4.2. Calculation of the grayer ____________________________________________

4.3. Calculation of trolley movement mechanism _______________________

4.4. Calculation of crane movement mechanism _________________________

4.5. Steel structure of the crane ___________________________________

4.6. Electrical part _________________________________________

5. Process Section _________________________________________

6. Safety and health ______________________________

7. Economic section __________________________________________

8. Conclusion of the ____________________________________________________

9. List of literature _____________________________________________

Introduction

Lifting and transportation machines are the main equipment for mechanizing work in various sectors of the economy: in industry, construction, in transport, in agricultural production.

The goat crane is a lifting structure for unloading and loading operations. This type of cranes is used at open sites of industrial enterprises, freight yards, landfills for the production of reinforced concrete products and container sites of railway stations.

Goat cranes are widely used, and their development is one of the most important in the field of PTM. The creation of rational and original designs largely depends on the ability to combine already known versions of the technique and introduce new ones that correspond to the high level of modern requirements

Analytical Overview

Gantry cranes consist of a span structure resting on support legs connected either directly to running bogies in self-tuning cranes, or to beams in which crane running wheels are installed. They are widely used for mechanization of loading and unloading operations at warehouses and landfills of construction products plants, at pre-assembly sites, installation of building structures and technological equipment, during the construction of the main buildings of thermal and nuclear power plants, laying concrete in a dam of hydraulic stations, installation of equipment of blast furnaces and cement roasting furnaces and other heavy industrial equipment. Goat cranes are divided into mounting and general purpose. General-purpose cranes have a lifting capacity of up to 5 tons, mounting cranes - up to 500 tons.

The main parameters of these cranes are:

1. Lifting height - 4-25 m;

2. Span - up to 40 m.;

3. Load lifting speed - up to 32 m/min.;

4. Crane speed - up to 100 m/min.;

5. Trolley speed up to - 40 m/min.

Speeds of all mechanisms of goat cranes are working.

The bearing structure of the goat crane is a bridge with two supports. Freight trolley with load gripping device moves along crane bridge. Crane supports are installed on running trolleys, each of which moves along two-rail track. Bridges of cranes of small (up to 5 tons) load capacity are made in the form of a three-lane spatial truss and an I-beam profile, along which the electric steel moves. Bridges of medium and heavy cranes are made in the form of a four-lane lattice truss of rectangular or trapezoidal section. Freight trolley of these cranes can move along lower or upper belt of bridge. Combined structures of cranes are common, in which a cargo trolley of the main one moves along the upper belt, and an auxiliary mechanism of lower lifting capacity along the lower one. Crane bridges are made with and without consoles. The length of the consoles reaches 25... 30% from the length of the span. In this case, the auxiliary lift trolley moves along the entire length of the span

When processing piece and bulk materials coming to the unloading site by water, by road or in other cases requiring an increase in the area served by the crane, the span of the goat cranes is carried out with one or two consoles.

The height of these cranes is chosen depending on the specified height of cargo lifting, as well as taking into account the dimensions of objects and structures above which it is necessary to move goods - racks, railway access roads with transport, stacks of materials, etc. Depending on the profile of the serviced platform, the running trolleys can be located at the same or different levels. In some cases, one of the running trolleys is located at the span level. Such cranes are called semi-roe cranes.

Most goat cranes are self-tuning. Crane bridge is laid by means of boom crane on sleeper cages, at the same time running bogies are installed on rails, support posts are pivotally connected with bridge belt and bogies, then left and right posts are tightened by means of winch and crane is installed in working position. Support struts at the bottom are connected by rigid crossbars (tightening of crane supports). The span of such a crane consists of a closed sheet structure of a trapezoidal shape, the freight trolley moves along rails laid on the side planes of the span.

In other structures, both support legs of goat cranes with a span of up to 30 m are rigidly connected to the span; with an increase in span, one leg is designed spatially rigid (left support), and the other - flat flexible (right support). Such a scheme eliminates the influence on the steel structure of the support crane, which can occur when the temperature is increased, which causes an extension of the span or when the parallelism of the crane track is violated.

Lifting mechanisms of goat cranes can be installed on cargo trolley or removed from it. In the first case, the freight cart is a conventional crane cart carrying a load lifting mechanism and a cart moving mechanism, or a special freight cart. Often, to reduce the weight and dimensions of the freight trolley, the load lifting and trolley movement mechanisms are removed from the freight trolley and installed above the rigid support. In these cases, the freight trolley carries the lifting mechanism polyspart units, and the traction force from the moving mechanism to the trolley is transmitted by the traction rope. As the weight and size of the trolley decrease, the load on the span decreases, which allows to reduce the weight of the crane as a whole.

Gantry cranes are typically controlled from a cab that is stationary or movable. The movable cabin provides a better view of the place of loading and unloading, but creates an additional movable load on the span, which causes the need to increase the section of the span. The stationary cabin is attached to the span near the rigid leg or directly to the support leg, which allows reducing the load on the span. However, with large spans, the view from the cockpit deteriorates significantly.

Design Section

Goat grab crane, with a lifting capacity of 10 tons, is designed for loading and unloading crushed stone. The crane is installed in an open warehouse. Operating temperatures range from 40 ° to + 40 °.

4.6. Electrical part

4.6.1 Selection of crane engines control system

The electric drive control system means a complex consisting of an electric energy converter, control equipment for switching current in the electric motor circuit, a manual control or automatic (program) control, a speed, track or other control, as well as protection elements of electrical equipment and a mechanism that ultimately act on the electric drive disconnection devices.

Electric drive control equipment is a complex including contact and contactless switching devices in electric motor circuits, energy and control converters, as well as elements of electric circuit protection.

If the contact switching elements of the device with a direct manual drive are intended for switching main current circuits, then such a device is called a power cam controller, and if these elements serve for switching control circuits, then such a device is called a command controller.

The crane control system used in this goat crane belongs to the category of devices under the continuous control of the operator, that is, in this system, the selection of the moment of start of the operation, speed parameters and the moment of end of the operation is carried out by the person controlling the mechanism. In turn, the control system provides the necessary switching sequence to realize the desired speed parameters, while preventing unacceptable overloads and providing the necessary protection.

In our case, an AC crane electric drive is used: an asynchronous motor with a phase rotor, controlled by a power controller (SC).

4.6.3. Selection of crane motor

Initial data for selection of electric motors of crane mechanisms are: static and dynamic loads given to the engine shaft; operating mode parameters; time of static and dynamic loads application, as well as technological features of mechanisms operation, which determine the number of cycles.

The task of selecting the crane mechanism engine includes pre-selection of the engine, its calculation to satisfy the thermal mode, as well as checking to ensure the specified accelerations (ensuring the starting mode and clutch margin for the movement mechanisms).

Process Section

To determine the residual life of steel structures of lifting machines (GPM) in service, the development of methods for determining critical values ​ ​ of the dimensions of fatigue cracks, their propagation speed depending on the load, stresses in the crack area and the number of loading cycles to their critical values ​ ​ are of paramount importance. Of all known defectoscopy methods, the acoustic emission (AE) method can most fully provide operational information about the location and kinetics of fatigue cracks, which makes it possible to effectively assess the degree of their danger.

AE is a physical phenomenon associated with the radiation of elastic waves of vibrations from a solid body during its loading. This radiation is associated with the rupture of the crystal lattice. The released fraction of elastic energy (emitted AE pulse) indicates the presence of a defect in the object to be diagnosed. The most informative diagnostic parameters of AE signals are the amplitude of elastic oscillations and their intensity. In order to predict the pre-decaying state of structural elements during their loading, it is necessary to establish correlation between the mechanical characteristics of structural materials and the parameters of AE signals under various loading modes.

Possible mechanisms for generating AE pulses during cyclic loading may be: accumulation of plastic deformations in the metal; sudden development of fatigue cracks; advancing and increasing the plastic deformation zone of the material in the area of the crack due to its advancement; mutual friction of the banks of fatigue cracks.

Diagnostic tools using AE methods include broadband piezoelectric sensors, amplifiers, analog-to-digital converters, digital signal processing units, and a computer with peripheral devices.

Economic section

In this part of the diploma project, a low-metal-intensive design of the span of the goat grab crane is being developed

The advantages of introducing a low-metal-intensive span structure are:

reduced weight and dimensions of the structure;

reduced labour input and time consumption during installation of goat grab crane.

Calculation was made from the introduction of a new span structure into production.

Calculation of integral economic effect from development and implementation of low-metal-intensive span structure

The basis of the economic calculation of the designed detachable connection of the span structure is the determination of its price and the basis of the economic effect.

Conclusion

One of the features of lifting machines is a rather large metal consumption, which leads to inconvenience during installation and causes their high cost. The design of low-metal structures is one of the most important engineering tasks.

The project developed a goat grab crane with a lifting capacity of 10 tons and a lifting height of 8 m. A distinctive feature of this crane is a low-metal-intensive main beam of a box section with a length of 32 m. The economic calculation of this steel structure was carried out and the integral economic effect of its implementation was determined.