Gantry Machine Tool Control for Asymmetrical Axis Load
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Solution Overview
Problem
Portal machines are often not operated at their maximum acceleration due to asymmetrical load distribution between gantry axes, leading to unnecessary extension of working time required to machine a workpiece.
Innovation Solution
A machine tool system with adjustable kinematic parameters based on the position of the tool-holding head, allowing higher maximum permissible speeds, accelerations, and jerks to be set without overloading axis drives, by dynamically adapting to asymmetrical load distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the maximum acceleration is specified for the maximally asymmetrical case, then the axis drives are not overloaded even when the tool holder is completely deflected to one side, but the working time required to machine a workpiece is unnecessarily extended
Solution Approach 1:
The patent applies dynamics by making the kinematic parameters (acceleration, speed, jerk) of the gantry axes dynamically adjustable based on the real-time position of the tool holder. Instead of using a fixed conservative maximum acceleration value, the control device continuously adapts the permissible acceleration values according to the current load distribution, allowing the system to operate at optimal performance levels while maintaining reliability.
Solution Approach 2:
The patent implements parameter changes by modifying the kinematic parameters (acceleration a, speed v, jerk j) of the gantry axes based on the position of the tool holder along the Y-axis. The control device calculates position-dependent maximum values for these parameters, enabling the machine to operate with higher accelerations when the load distribution allows, thereby reducing machining time while preventing axis drive overload.
2Productivity
If the tool holder is positioned midway between the gantry axes, then the load distribution is symmetrical and maximum acceleration can be achieved, but the tool holder cannot be positioned at other locations without reducing acceleration
Solution Approach 1:
The system dynamically adjusts the kinematic parameters based on the tool holder's position. When the tool holder is at the central position, maximum acceleration is permitted. When the tool holder moves to asymmetric positions, the control device calculates and applies position-dependent acceleration values that optimize performance for each specific position, maintaining high productivity across all operational scenarios.
Solution Approach 2:
The control device implements parameter changes by establishing a functional relationship between the tool holder position and the permissible acceleration values. For each position of the tool holder along the Y-axis, the system determines the appropriate maximum acceleration, speed, and jerk values, allowing the machine to adapt its kinematic parameters to match the current load distribution and maintain optimal performance.
Data Source
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AI summary
In a machine tool system (1) comprising a machine tool (2), comprising: - a stationary machine base (6); - two support elements (7, 8) aligned parallel in a third spatial direction (Z) and connected to the machine base (6); - a crossbeam (9) connected to the two parallel support elements (7, 8) and aligned in a second spatial direction (Y); - a tool holder head (10) attached to the crossbeam (9) and adjustable along the crossbeam (9) in the second spatial direction (Y) by means of a second drive means along a second machine axis (Y1); - wherein the crossbeam (9) is adjustable along the third spatial direction (Z) with respect to the support elements (7, 8) by means of a third drive means along two parallel third machine axes (Z1, Z2); and/or - the two support elements (7, 8) are adjustable along a first spatial direction (X) with respect to the machine base (6) by means of a first drive means along two parallel first machine axes (X1, X2);and a control unit (3) connected to the machine tool (2) for controlling the first, second and/or third drive means, the machining time for the processing and/or machining of the workpiece is to be reduced. For this purpose, the invention provides that at least one kinematic parameter of the first (X1, X2) and/or third machine axes (Z1, Z2) can be predefined as a function of the position of the tool holder (10) with respect to the second machine axis (Y1). The kinematic parameter, in particular the maximum speed and/or the maximum acceleration and/or the maximum jerk of the respective machine axes, can thus be adapted to an asymmetrical load distribution caused by the movement of the tool holder (10).