Part i - spindle facts

HSK-Clamping Unit / Design B
• A newly designed coating optimizes the life span 50
times in the case of insufficient lubrication.
• The guiding of the gripper is done by means of a
specially formed locating sleeve, which sits the tool
directly into the taper.
• New also are the geometry and the coating of the
spacer. The position of the individual gripper fingers
are securely held and guided to ensure a perfect
balance at high speed.
Quickest clamping now depends only on the machine tool
control and its software
With regard to spindle design, the drawbar presents some
challenges. A drawbar is a movable device, and with each
actuation the springs may end up in slightly different
locations. This can create a balance problem, which could
cause unwanted vibration at high speeds. To overcome this,
drawbar components should be manufactured to close
tolerances, and with guide bushings positioned internally.
Also, as speeds increase, the holding force required also
increases. It is not practical to increase the holding force
by simply increasing the number of washers, as this
would require a longer spindle shaft. It is also not always
practical to increase the diameter of the washers, as this may require the shaft to be larger
imposing on spindle speed.
Mechanical locking systems
Figure 43. HSK Clamping unit –
Design B
The mechanical clamping system offers the highest pull forces. Special features of the power
drawbar are the amplification mechanism for transmission of the pull force and locking the
universal spindle’s inside shape. The drawbar uses belleville washers to pull the toolholder into
the taper. Once seated, however, a mechanical locking system then is actuated. The locking
components may be small balls or cams.
Figure 44. Mechanical locking system
- 39 -