What is an MSU Sensor System for Drawbar Monitoring?

May 29, 2018

By: Harold GoellnerOTT-JAKOB Drawbar Specialist

An MSU sensor system is a built-in, multi-sensor and electronic evaluation system in the unclamping unit of a drawbar. In machining, the drawbar supplies the force that keeps the tool and the toolholder assembly in the spindle even as the spindle rotates. 

Unclamp unit: Release stroke and shaft suspension.
Hydraulic unclamp unit with rotary union.

Optimal drawbar force is essential, especially where high spindle speeds, precision boring, or heavy cutting forces are required. Overtime, the drawbar force can weaken due to vibration and friction, potentially causing a spindle crash. There are several signs that your drawbar may be compromised and losing force, including:

  • Chatter that leads to changes in cutting performance
  • Fretting that results in a coppery discoloration and degradation on the toolholder’s taper
  • Degradation of the surface finish
  • Repeatability, the inability of your machine to repeat or duplicate a motion or action within a specific tolerance range.


MSU Sensor System Provides Preemptive Maintenance

Integrating an MSU sensor system into your unclamping unit provides preemptive maintenance that detects drawbar disruptions during the machining process. The ability to monitor your drawbar force and detect potential deficiencies prevents catastrophic failures, machine tool crashes, and downtime.

 Distance measurement system electronically senses the position of the drawbar in unclamped, tool clamped (clamped with tool), or clamped without tool
Distance measurement system electronically senses the position of the drawbar
in unclamped, tool clamped (clamped with tool), or clamped without tool

 

An MSU system for drawbar monitoring combines a distance measurement and piston position sensor.

The distance measurement system data collection for unclamped unit
The distance measurement system data collection for unclamped unit

 

Distance Measurement in an MSU Sensor System

The distance measurement in an MSU sensor system electronically senses the position of the drawbar shaft. It also informs the PLC of the machining center if the drawbar is in unclamped, tool clamped (clamped with tool), or clamped without tool position.

Monitoring the position of the drawbar prevents you from running the spindle unless a tool is clamped in the receiver. It also ensures that the drawbar is in unclamped position before the tool changer releases a tool.

A distance measurement sensor system makes the spindle more state-of-the-are by replacing the traditional mechanical signal ring and prox switches with electronic components.

Piston Position in an MSU Sensor System

The unclamped piston position monitoring electronically senses if the unclamp piston in the pneumatic and hydraulic units is in the clamped position before the spindle begins rotating. This ensures that the unclamped piston does not come into contact with the rotating drawbar and spindle during the machining process. If the unclamp piston comes into contact with the rotating elements, the unclamp piston will weld itself to the drawbar.

 The piston control of the unclamped unit features an M8x1 connector, proximity switch, 24V DC, and digital output.
MSU sensor system

The MSU sensor system also has an optional leakage sensor that monitors the drainage flow. To learn more about why leakage monitoring is important, click the button below.

CONTACT A DRAWBAR SPECIALIST

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