Servo Press Ram Force Control via Feedback
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Solution Overview
Problem
Servo-motor driven ceramic and metal powder presses face challenges in precise force control due to the inefficiencies in spindle operations, which are influenced by temperature and other variables, leading to unsynchronized operation and inability to guarantee torque limitation, especially in multi-platen presses with screw drives.
Innovation Solution
Implementing a control method where electric motor drives adjust press rams along a set position path, using measured forces to readjust and regulate the position setpoints, converting force control deviations into target position control variables, and accounting for temperature and structural variables to ensure precise force control, particularly for floating axes in servo spindle drives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a servo motor with spindle drive is used to adjust press rams, then automation and control capability are improved, but force control precision deteriorates due to spindle efficiency variations influenced by temperature
Solution Approach 1:
The patent implements feedback control by measuring the actual force exerted by the press ram during operation and using this measurement to correct the position setpoints. The control device continuously monitors the force deviation from the target force profile and adjusts the press ram position accordingly, compensating for spindle efficiency variations and temperature effects to maintain precise force control despite automation.
2Manufacturing precision
If a spindle drive system is used for press ram adjustment, then positioning capability is improved, but synchronization between multiple axes deteriorates due to unknown efficiency variables
Solution Approach 1:
The patent uses feedback from force measurements on each axis to compensate for synchronization deviations. By monitoring the actual force and position deviations of multiple press rams and adjusting their setpoints independently based on measured force profiles, the system maintains reliable synchronization even though spindle efficiency variables are unknown and vary with temperature.
3Force
If torque limitation is implemented through drive control, then force control capability is improved, but precision deteriorates because spindle efficiency is a virtually unknown variable
Solution Approach 1:
The patent overcomes the unknown spindle efficiency variable by implementing direct force measurement and feedback control. Instead of relying on theoretical torque calculations that are affected by unknown efficiency, the system measures the actual force exerted and uses this feedback to accurately control and limit the force applied during the pressing process, achieving precise force limitation despite the virtually unknown spindle efficiency.
4Adaptability or versatility
If floating axis operation is implemented, then adaptability to material variations is improved, but control complexity increases due to additional readjustment requirements
Solution Approach 1:
The patent manages the increased control complexity of floating axis operation through systematic feedback control. By measuring force deviations and automatically calculating corrected position setpoints based on the measured force profile, the system handles the adaptability requirements of floating axes without proportionally increasing operational complexity. The feedback mechanism automates the readjustment process, making the system adaptable to material variations while keeping control manageable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables reliable force control and readjustment of press rams, ensuring precise synchronization and operation of multiple axes, improving the overall efficiency and accuracy of the pressing process by using measured forces to adjust target positions dynamically.
Implementation Method 1
The force of the tool axis, i.e. in particular the force measured on one of the components from the press ram to its fixed point relative to a frame and, if necessary, relative to other tool axis is measured with suitable sensors or a suitable force measuring device in the translatory movement during a running press cycle.
Data Source
Figure 1
AI summary
The invention relates to a method for controlling a ceramic or metal powder press, and to a ceramic or metal powder press (1) for pressing a material to be pressed (6), wherein at least one electromotive drive (15, 16; 20, 21), which displaces at least one plunger (5; 4) in a longitudinal pressing direction, is actuated such that the drive (15, 16; 20, 21) displaces the plunger (5; 4) along a desired position path (as1), and the drive is reset if it deviates from the desired position path (as1), a measured force (F11, F12), which acts upon the material to be pressed (6), on the plunger (4) or on components (17-19) supporting said plunger, being used for resetting as at least one manipulated variable. The invention relates to a ceramic and/or metal powder press (1) which is designed to perform the method.