Rotary Tablet Press Punch Position Measurement
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Solution Overview
Problem
Existing rotary tablet press measurement systems are insufficient for accurately and reliably measuring the vertical position of rotatably driven rotor punches across the entire circumference, particularly outside of pressing stations, which affects the assessment of compression characteristics and tablet quality.
Innovation Solution
A device featuring a scale integrated onto the upper and/or lower punches, readable by a rotating reading device, allows for precise measurement of vertical position and movement along the entire circumference, with optional wireless data transmission for comprehensive monitoring and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If press force measuring devices are used to monitor the pressing process, then the pressing force can be monitored and controlled, but the vertical position of punches outside of pressing stations cannot be accurately measured
Solution Approach 1:
The measurement system is segmented into multiple independent measurement points around the rotor circumference. Multiple scales are positioned at different locations (including filling stations, ejector stations, and pressing stations) to independently measure vertical positions at various stages, enabling comprehensive monitoring throughout the entire rotational cycle rather than relying on a single pressing station measurement.
Solution Approach 2:
A scale is introduced as an intermediary element attached to the punch assembly. This scale serves as a mediator between the moving punch and the stationary reading device, allowing the reading device to accurately track vertical position changes without direct mechanical contact with the punch itself, thereby enabling measurement across all circumferential positions including non-pressing areas.
2Measurement precision
If incremental path measuring systems with mechanical contact are used, then displacement can be measured, but mechanical contact is required which increases complexity
Solution Approach 1:
The mechanical contact measurement system is replaced with a non-contact optical measurement system. The reading device uses optical fields (light) to read the scale markings without physical contact, substituting the mechanical interaction with an electromagnetic field-based interaction. This eliminates the complexity of mechanical linkages, friction, and wear while maintaining measurement precision.
Solution Approach 2:
Instead of directly measuring the physical displacement through mechanical contact, the system creates an optical copy or representation of the position information through the scale markings. The reading device reads these markings to determine position, effectively copying the position information into an optical domain that can be processed without mechanical contact.
3Productivity
If measurement data is collected only in compression phase at pressing stations, then pressing force monitoring is sufficient, but vertical movements in filling and ejector areas remain undetected
Solution Approach 1:
The measurement coverage is segmented to include multiple functional areas around the rotor: filling stations, ejector stations, and pressing stations. Each area has its own measurement point, dividing the monitoring task across multiple locations to ensure comprehensive data collection throughout the entire punch trajectory, preventing information loss in any specific region.
Solution Approach 2:
The measurement system operates continuously throughout the entire rotational cycle of the rotor, not just during the compression phase. The reading devices continuously track the scale markings as the punches move through all stations, ensuring uninterrupted measurement of vertical positions from filling through ejection and pressing, eliminating gaps in measurement data.
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
Enables reliable and precise measurement of vertical position and movement of punches throughout their rotation, allowing for comprehensive analysis of compression characteristics and detection of unforeseen movements, thereby improving tablet quality control.
Implementation Method 1
The reading device can be designed to read the scale optically, magnetically, capacitively and/or inductively
Implementation Method 2
The reading device can be designed to read the scale optically, magnetically, capacitively and/or inductively
Implementation Method 3
The reading device can be designed to read the scale optically, magnetically, capacitively and/or inductively
Implementation Method 4
The reading device can be designed to read the scale optically, magnetically, capacitively and/or inductively
Data Source
Figure 1
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AI summary
The invention relates to a device for measuring the vertical position of upper and lower punches (18, 20) arranged in pairs and rotating synchronously with a rotatably driven rotor (12) of a rotary tablet press, which perform a vertical movement in certain areas along the circumference of their rotation during one rotor revolution. The device has at least one scale (54) arranged on at least one of the upper and/or lower punches (18, 20) and extending parallel to the vertical direction of movement of the respective upper and/or lower punch (18, 20), and at least one reading device (56) associated with the scale (54), which also rotates synchronously with the rotor (12) and with which a vertical position of the respective upper and/or lower punch (18, 20) can be measured by reading the scale (54). The invention also relates to a corresponding rotary tablet press and a corresponding method.