Duplex worm

In contrast to normal teeth ( also called simplex worm gears ), the tooth flanks of duplex worm with slightly different modules or form numbers are produced. This result for the two tooth flanks different pitch angle, so that the tooth thickness or gap about the width worm gear continuously changed. In the worm, the different modules lead to different profile shift coefficients and Wälzkreisdurchmessern and thus divergent edge shapes for the front and back edges. The tooth thicknesses and gaps remain constant around the circumference of the wheel. The game setting takes place by axial displacement of the screw, so that just the range of worm gearing with the backlash matching tooth thickness with the worm wheel for engagement comes ( Figure 1).

The backlash can be set to any value at any time and re-adjusted sensitively and continuously, without changing the engagement conditions of the teeth.

Other ways to play adjustment

In addition to the duplex method, there are basically the following options, the backlash of a worm drive on and recreate:

• Change in the axial distance by eccentric bushes in which the worm shaft and / or the worm wheel are mounted twisted within the housing.
• Axial displacement of a conical screw performed (Fig. 2a )
• Division of the worm in two halves (Fig. 2b), the twisted or moved relative to one another ( system Ott )
• Dividing the wheel into two discs ( Figure 2c ), which are rotated relative to each other.

All these methods, however, have significant disadvantages:

• Spielein - or - enactments distort geometrically exact meshing.
• You move the contact pattern and change its shape and size.
• Thus they reduce the carrying capacity, and decrease the efficiency.
• Each adjustment attracts a large initial wear by itself.
• The risk of incorrect setting and destruction of the worm drive is great.

Duplex gears not know these problems.

They allow a toothing geometrically exact and moreover very sensitive play adjustment. Neither the once -trained support image, nor the carrying capacity or the efficiency can be affected. Moreover, the duplex toothing, designed as involute, are relatively insensitive center distance, for example as a result of screw bends.

Setting of the game

When installing and setting a DUPLEX wheelset, proceed as follows:

• Shaft and wheel are mounted successively. The arrows the direction of adjustment on both parts pointing in the same direction. (Fig. 1)
• The shaft is to be mounted with bearings in an axial position before zeroing. She has in this position game to the wheel
• The wheel is mounted in its housing, but is still axially, ie transversely to the screw shaft axis, sliding.
• Both auger edges are inked, and the shaft is rotated by hand in both directions by at least 2 x 360 °, so that the blueing of the screw flanks in the contact area (load image ) is transferred to the wheel flanks.
• The wheel is now as long as along its rotational axis ( axial), move to forward and trailing edge of the wheel show approximately equally distant from the center of contact patterns.
• The wheel is fixed in this optimal achievable center position of the supporting images.
• The shaft can then be screwed down to zero ( at the level of the notch of the axle ) or to another desired game.
• Now, the shaft is axially secured in this position.

Applications

To use duplex gears are used everywhere, where a backlash between shaft and sprocket is undesirable or harmful,

• In order to achieve high positioning accuracy, in both directions of movement
• To avoid a damaging pulse- prone plant edge change in load direction changes

So for example:

• As a drive in rotary and tilting tables
• As adjusting drive in milling heads
• In press adjustments