Spindle Braking During Retraction to Cut Machine Tool Heat
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Solution Overview
Problem
Thermal issues in machine tools, particularly in tapping centers, reduce spindle performance and productivity, with conventional methods of accelerating the spindle at or slightly above rated current leading to inefficient dynamics and excessive heating.
Innovation Solution
Implementing a method that brakes the spindle during retraction and travel movements, specifying retraction and travel movements in the parts program, and using loss-minimal movement profiles to reduce thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the spindle is accelerated at rated current or slightly above rated current to solve thermal problems, then thermal load is reduced, but dynamics and acceleration performance deteriorate (only about a third of possible acceleration is achieved)
Solution Approach 1:
The spindle is decelerated during retraction movement before the tool changes direction, preparing the spindle for the next acceleration phase. This preliminary deceleration reduces thermal load during high-speed operations while maintaining dynamic performance by optimizing the timing and magnitude of deceleration forces.
Solution Approach 2:
The control system applies periodic deceleration during retraction movements interspersed with high-speed acceleration during machining operations. This periodic application of deceleration forces allows the spindle to dissipate heat during low-load periods while maintaining high acceleration capability during productive machining phases.
2Productivity
If the spindle operates at high acceleration to improve productivity, then machine productivity increases, but thermal load increases (reducing productivity)
Solution Approach 1:
The deceleration forces applied during retraction movements, which would normally be considered wasted energy or harmful thermal load, are converted into a beneficial thermal management strategy. By intentionally applying deceleration during non-productive retraction phases, the system uses these moments to reduce spindle temperature, thereby enabling sustained high-productivity operation without thermal damage.
Solution Approach 2:
The control system dynamically changes operational parameters by applying deceleration forces during retraction movements. This parameter change (from acceleration to deceleration) during non-productive phases allows thermal management without compromising overall productivity, as the deceleration occurs during necessary tool repositioning time that would otherwise be idle.
3Temperature
If the tool is braked during retraction and travel movements, then thermal load is reduced by 25-32%, but energy consumption increases
Solution Approach 1:
Instead of continuously braking the spindle, the control system applies partial braking actions only during retraction and travel movements when the tool is not engaged in productive machining. This partial application of braking force reduces thermal load during non-productive phases while minimizing energy consumption by avoiding continuous braking during high-value machining operations.
Data Source
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AI summary
The invention relates to a method for controlling a rotational movement of a tool (6) on the basis of a parts program in a machine tool (1), wherein a retraction movement and a travel movement to be carried out by the tool (6) are specified in the parts program, wherein the rotational movement (D) of the tool (6) is braked during the retraction movement and/or travel movement.