Worm Gear Dimensional Chain Calculation - Metrology, Standardization and Interchangeability - Exchange Rate

Contents

Introduction

Select Smooth Cylindrical Joint Fits

Rolling Bearing Fits

Selection of key connections

Worm Wheel Press Fit Calculation

Calculating the Dimension Chain

Compensator calculation

List of literature used

Summary

In this course design, the dimensional circuit of the reduction gear unit is calculated, which includes solving the inverse problem. The inverse task is a task in which the parameters of the component links are set and you need to define the parameters of the closing link.

Introduction

Gearboxes are widely used in various areas of mechanical engineering.

The unification of gearboxes is based on the standardization of their main parameters: axle distances, gear ratios, wheel width factors, etc.

Worm gears are used both in lifting machines and in drives of various transport machines. Also, worm reduction gears have the property of self-braking, when the elevator motor is de-energized, the reduction gear is self-braking and does not allow the elevator to fall. Like other gearboxes, worm gearboxes allow for overload protection. The safety element is a key on the input shaft, which is made of a shorter and more "weak" material than the other keys. So, for example, when the elevator is jammed, this key is cut off and the electric motor does not burn out.

However, along with useful properties, worm gearboxes also have a number of disadvantages: low efficiency (compared to gear gearboxes), since they have sliding friction, which causes increased heating of the gearbox, energy consumption, etc. To reduce friction, prefabricated worm wheels consisting of a hub and a rim are used. A crown made of non-ferrous metal (bronze, etc.) allows you to reduce friction in gear. Such prefabricated worm wheels are manufactured at high sliding speeds, at low speeds it is possible to manufacture a worm wheel rim from cast iron.

The engagement of the worm and the worm wheel is controlled by longitudinal movement along the shaft axis of the worm wheel. Adjustment of engagement is necessary to set a certain contact spot, to ensure less wear of the worm and worm wheel.

Compensator calculation

Thickness of permanent gasket is taken equal to 1 mm. The maximum offset of the axial distance of the worm wheel and the worm to the left is 0.175mm, to the right is 0.805mm. We select the necessary gaskets to compensate for the size of the beat.

A number of gaskets: 0.01mm, 0.02mm, 0.04mm, 0.08mm, 0.15mm, 0.16mm, 0.32mm, 0.64mm, etc.

We select the required gaskets: 0.825mm0.64mm0.04mm0.02mm = -0.005mm

On the left side of the gearbox housing, beat compensation is performed due to the installation of the axial play, with an axial gap of up to 0.04mm.