Rotary Press Upper Punch Adherence Prevention
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Solution Overview
Problem
Rotary presses face issues with material adherence to punches during the return stroke, especially for noncircular compact shapes, affecting the quality of the compact and subsequent pressing processes.
Innovation Solution
The rotor is equipped with means to prevent adherence, including rotatable upper punches, dimensionally stable anti-adhering plastic inserts, an impacting mechanism, heating/cooling devices, and a cleaning system to address material sticking, ensuring complete die coverage and effective pressing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the upper punch is made rotatable to eliminate adherence, then material adherence is reduced, but the solution becomes unsuitable for noncircular compact shapes
Solution Approach 1:
The punch is made rotatable during the return stroke to dynamically change its orientation, which prevents material adherence by varying the contact surface. This dynamic motion allows the same punch design to effectively handle both circular and noncircular compact shapes, as the rotation prevents material from settling in fixed adherence patterns.
Solution Approach 2:
The punch surface properties are changed by using different materials or coatings with varying friction characteristics. This allows the punch to control material adherence through parameter changes in surface friction, enabling effective pressing for both circular and noncircular shapes without being constrained by shape-specific designs.
2Productivity
If the upper punch extends into the die during pressing, then the pressing process is conventional, but material adherence occurs on the pressing surface during return stroke
Solution Approach 1:
The punch surface is preliminarily treated with anti-adherence coatings or materials before the pressing process begins. This preliminary preparation prevents material adherence from occurring in the first place, allowing the punch to maintain continuous contact with the material during pressing while preventing sticking during the return stroke.
Solution Approach 2:
An intermediary layer or coating is introduced between the punch surface and the material to prevent direct contact and adherence. This intermediary layer allows effective pressure transmission while preventing material from bonding to the punch surface, resolving the contradiction between pressing efficiency and adherence prevention.
3Area of stationary object
If the pressing surface diameter is larger than the die hole diameter to cover the die completely, then die coverage is improved, but the upper punch may contact the die plate edge
Solution Approach 1:
The punch and die geometries are designed with asymmetric relationships where the punch diameter is optimized to provide complete die hole coverage while maintaining sufficient clearance from the die plate edge. This asymmetric design allows the pressing surface to be large enough for complete coverage without creating harmful contact conditions.
Solution Approach 2:
The clearance between the punch and die plate edge is optimized in the radial dimension while the vertical pressing dimension maintains full contact. This dimensional differentiation allows the pressing surface to completely cover the die hole area while preventing contact with the die plate edge through proper radial spacing.
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
Prevents continuous adherence to punches, maintains compact quality, and facilitates efficient pressing processes even for noncircular shapes by using rotatable punches, anti-adhering inserts, and cleaning mechanisms.
Implementation Method 1
bear the punches rotatably in the punch guides and to set them in a rotationary motion during the return stroke after a pressing process. By means of the rotation of the punches, the adherence effect can be eliminated to a large extent.
Implementation Method 2
the rotor can be provided with an impacting mechanism which gives one or several impacts on the upper punch during the return stroke of the punch. Thereby, a compact that adheres to the pressing surface is getting loosened.
Implementation Method 3
to provide a device for heating or cooling of the upper punches. A cooling makes sure that an adherence is prevented from the outset. A heating can primarily give rise to a loosening of adhering material.
Data Source
AI summary
Rotary press comprising a rotor rotatably driven about a vertical axis, said rotor exhibiting a die plate and upper and lower punches which are vertically guided in guides of the rotor working together with die holes in a die plate, at least one press station which exhibits an upper and a lower pressure passed by the punches and through which the punches are moved towards the die hole in order to compress the material in the die hole, characterized in that the rotor is provided with means which act upon compacts or parts thereof which adhere to the pressing surface or which means eliminate or prevent an adherence of a compact or parts thereof to the pressing surface of the upper punch, respectively, during the return stroke.