DetMash (Machine Details)

Introduction

The performance of course work is the most important stage in the development of an engineer in the specialty 0.0 Operation and maintenance of ship power plants. Only in the process of self-design can you better study the design of the designed machine, more deeply understand why the elements of this machine are made in this way, and not otherwise.

The purpose of the course work is to design a single-stage worm reduction gear with a lower location of the worm. During the work, the main parameters of gear engagement are determined, and its calculation is carried out according to the criteria of contact endurance and fatigue during alternating bending. Gear shafts are designed and tested for stiffness and fatigue strength. The selected bearings are checked. The gearbox is assembled based on the design results.

Worm reducer is one of the classes of mechanical reducers. Gearboxes are classified by type of mechanical transmission. The gearbox is called worm-like in the form of a worm gear located inside the gearbox, transmitting and converting torque. The screw that underlies the worm gear looks like a worm, hence the name. Worm gear can be provided with one or more mechanical planetary gears. In the worm gear, the increase in torque and the decrease in angular velocity of the output shaft are due to the conversion of energy enclosed in the high angular velocity and low torque on the input shaft.

A reduction gear is a mechanism consisting of gear or worm gears, made in the form of a separate unit and serving to transfer power from the engine to the working machine.

Reduction gears - material and technical products, serve to change the speed of rotation when transmitting torque from one shaft to another. All this is mechanics, or, more precisely, machine parts.

Worm gearbox is used when transmitting motion between crossing axes. One of the significant advantages of worm gears is the ability to obtain a large gear ratio in one stage. Such gearboxes have high smoothness, silent operation and self-braking at certain gear ratios, which allows excluding braking devices from the drive.

There are various versions of these mechanisms, for example, single-stage universal, two-stage, three, single-stage with the lower location of the worm, with the upper location of the worm, with the lateral location of the worm.

The output of the gearbox shaft with the side arrangement of the worm, depending on the purpose and arrangement of the drive, can be made up or down. Lubrication of bearings in such gearboxes will be difficult.

Gearbox assembly

Before assembling, the interior of the housing must be thoroughly cleaned and covered with oil paint. The gearbox shall be assembled in accordance with the general view drawing.

The following assembly sequence is provided: impellers, holding rings, ball radial-thrust bearings 46309 are installed on the worm shaft, preheating them in oil up to 80... 100C.

At the beginning of assembly of the worm wheel shaft, a key is laid and then the wheel is pressed until it rests against the shaft collar (previously, the worm wheel consisting of a cast iron hub and a bronze rim is assembled); Then, spacer sleeve and roller conical bearings 7211 preheated in oil are installed. The assembled shaft is laid in the base of the housing and covered with a cover, before covering the surface of the flange joint with alcohol varnish. The housing cover is centered by two conical pins.

Adjustment of radial thrust bearings is carried out by a set of thin metal gaskets I and II (Fig. 6) installed under the flanges of bearing covers.

To adjust the worm engagement, the entire worm wheel shaft set must be axially displaced until the middle plane of the wheel coincides with the worm axis.

This is achieved by transferring part of gaskets II from one side of the housing to another. In order to maintain bearing adjustment, the total thickness of gasket set II must remain unchanged.

Plug of oil discharge hole with gasket is screwed into oil indicator. Oil is poured into reducer and inspection hole is closed with cover with perfume.

The assembled gearbox must be run in and tested on the bench.