Spindle Without Integral Dsp - HEIDENHAIN TNC 426 PB/M Technical Manual

Table of Contents

6.12.6 Braking the Spindle for an Emergency Stop

Spindle without

integral DSP

December 2001

For an emergency stop the spindle must be braked as quickly as possible. If

the braking energy cannot be drawn off quickly enough, the dc-link voltage

increases sharply. Under circumstances, the inverter could switch off and the

spindle coast to a stop. A powerful braking of the spindle also leads to a high

strain on the mechanics of the machine.

All of the following braking strategies are also effective when braking the

spindle with M05, if the brake ramp in M05 is steeper than the brake ramp in

the emergency-stop braking strategy.

Controls without integral spindle DSP offer you three strategies for braking the

spindle in an emergency stop. If you use a second digital spindle, all three

strategies are available for it:

Strategy 1: The maximum braking current is monitored and, if required,

Strategy 2: The regenerated power is influenced by a time constant.

Strategy 3: The brake ramp can be entered.

The nominal velocity 0 is output for strategies 1 and 2.

The strategies are also effective during a power fail and with M05 if the brake

ramp set in MP3411 and MP3412 is steeper than the brake ramp which would

result from the strategies.

The strategies are not mutually exclusive, meaning all strategies may be

activated. In an emergency stop the first addressed strategy becomes

Inverters with regenerative power supplies usually do not develop problems if

they are switched off. The main concern here is for the mechanics of the

Problems with inverters with braking resistors can arise if the drive is switched

off too early. The strain on the mechanics is reduced, but can also be

influenced with braking strategies. Strategy 3 is recommended for both

inverter systems.

Enter MP236x = 0 and MP2191 = 1.

Enter a high value in MP259x.

Use the emergency stop to brake the spindle from the maximum speed.

Decrease the value entered in MP259x until the braking time is as short as

possible and the mechanics of the machine are not stressed too much.

Enter MP236x = 0 and MP259x = 0.

Enter MP2191 = 1.

Enter MP2191 = 0 and MP259x = 0.

In MP236x, enter a high value, e.g. 4.

Use the emergency stop to brake the spindle from the maximum speed.