Mast Crane Calculation - DBE, Drawings

Introduction

Derrick - cranes are used in many sectors of the national economy in technological, loading, installation and other works.

Crane consists of rotating mast, boom, rigid rods hinged in lower part and supporting upper support unit of mast, lower part of mast rests on bearings.

Mechanisms for lifting, changing departure, turning can be installed both on a special platform rotating together with the mast, and in a separate room outside the crane; mixed system of mechanisms installation is possible. Hook lifting mechanism is equipped with multiple load polyspast, rope departure change mechanism. If the winches of these mechanisms are located outside the platform, then they are installed in a special room and the ropes are wired through the lower bearing of the mast. The rotation mechanism may be the same as the gantry cranes. More often, a rope rotation mechanism is used., the winch of which is installed on the platform, and the rope, running off the drum and passing through guide blocks installed on rotary and non-rotary frequent, envelopes a fixed circular chase.

Their carrying capacity reaches 300 tons, boom departure up to 50 m, lifting speed 310 m/min, rotation speed 0.3-0.75 rpm, boom departure change speed 1-5 m/min.

1 Calculation of lifting mechanism.

1.1 Initial data.

- lifting capacity, Qn = 250t

- load lifting range, D = 30 m

- lifting speed Vp = 1, 25m/min = 0, 021m/s

Other initial data are given in the task form.

1.2 Brief description of the lifting mechanism structure.

Torque from the electric motor is transmitted through a reduction gear, after which it increases in open gear. Torque is transmitted through shaft from coupling installed on slow-moving shaft of reduction gear to open gear through which torque is transmitted to rope drum.

4.3 Check and configuration of safety devices and devices.

We configure safety devices and devices as follows:

Lifting mechanism:

- lifting height limiter actuates at the distance of not less than 200 mm from boom tip

- load capacity limiter, actuates when the load capacity exceeds 15% of the nominal

Boom departure change mechanism:

- maximum (minimum) boom departure limiter actuates at boom approach to maximum and minimum flight mark. At that, at least 1.5 turns of rope must remain on rope drum until attachment.

- maximum departure limiter at maximum lifting capacity.

Rotation mechanism:

- crane turning limiter actuates when the crane approaches boundary positions, at the distance of not less than full braking path of the turning mechanism.

In addition, zero interlock, phase break monitoring relays, audible signal, emergency switch, departure indicator must be serviceable on the crane.

4.4 Crane test.

Static test of crane:

Static tests of the crane are carried out with a load 25% higher than its passport carrying capacity.

During static tests of the crane, the boom is set relative to the rotary support part to the position corresponding to the highest load capacity of the crane and/or the highest load moment, and the load rises to a height of 100200 mm.

The crane is considered to have passed static tests if within 10 minutes the lifted load does not descend to the ground, and no cracks, residual deformations and other damage to steel structures and mechanisms are found.

Dynamic crane test:

Dynamic tests of the crane are carried out by a load, the mass of which exceeds its passport carrying capacity by 10%, and are aimed at checking the operation of its mechanisms and brakes.

During dynamic tests of cranes (except for cable type cranes), multiple (at least three times) lifting and lowering of cargo is carried out, as well as checking the action of all other mechanisms when combining the working movements provided for by the crane operating manual.

The results of the technical inspection of the crane are recorded in its passport by the engineer-technician for supervision of the safe operation of lifting cranes, who carried out the inspection, with the indication of the date of the next inspection. When examining the newly installed crane, the record in the certificate shall confirm that the crane is mounted and installed in accordance with these Rules for the arrangement and safe operation of lifting cranes, the operating manual and has passed the tests.

Conclusion.

In this course design, the calculation of the mast crane with a lifting capacity of 250 tons was considered and given. The operation of the mechanisms is described. Main units and crane elements are selected. Data on crane operation, maintenance and testing are given.