Plug Assist Drive Assembly for Thermoforming
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Solution Overview
Problem
Thermoforming machines face challenges in achieving a balance between sufficient torque and fast stroke to optimize article formation and surface finish, as existing drive mechanisms either lack the necessary speed or forming pressure.
Innovation Solution
A third motion platen driven by a plug assist drive assembly with elongated gear racks and a bevel gearbox, powered by a servo motor, enables quick movement of plugs into mold cavities with high forming pressures, utilizing a combination of gear racks and a drive source to impart linear reciprocation and co-rotation, enhancing the speed and force of plug advancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single roller screw shaft is used to drive plugs, then the structure is simplified, but the stroke speed is insufficient and surface finish is compromised
Solution Approach 1:
The single roller screw shaft is segmented into multiple individual roller screw shafts, with each shaft driving a separate plug. This segmentation allows each plug to be driven independently at optimal speed, resolving the contradiction between structural simplicity and stroke speed by distributing the driving function across multiple simpler components rather than one complex centralized system.
Solution Approach 2:
The drive mechanism transitions from a static, unified roller screw shaft to a dynamic system where multiple shafts can operate with independent motion control. This enables each plug to achieve optimal stroke speed dynamically, improving surface finish while maintaining relatively simple individual shaft structures.
2Device complexity
If a single roller screw shaft is used to drive plugs, then the structure is simplified, but sufficient torque for forming pressure is not achieved
Solution Approach 1:
The single roller screw shaft is divided into multiple individual roller screw shafts, each capable of generating independent torque. The cumulative torque from multiple shafts provides sufficient forming pressure while keeping each individual shaft structurally simple, resolving the contradiction between device complexity and force output.
Solution Approach 2:
Multiple roller screw shafts are combined in parallel to drive multiple plugs simultaneously. The individual shafts work together to generate cumulative torque and forming pressure, achieving the force requirements of complex single-shaft systems while maintaining the structural simplicity of individual shafts.
3Productivity
If plugs are advanced quickly into mold cavities, then productivity is improved, but sufficient forming pressure is not achieved
Solution Approach 1:
The drive system enables dynamic control of each plug's motion, allowing rapid advancement for high productivity while maintaining the capability to generate sufficient forming pressure through the combined action of multiple roller screw shafts. Each shaft can independently adjust its torque and speed characteristics.
Solution Approach 2:
The segmented drive system with multiple independent roller screw shafts allows each plug to be advanced at optimal speed while the collective system provides sufficient forming pressure. This segmentation resolves the contradiction by distributing both speed and force functions across multiple components.
4Manufacturing precision
If forming pressure is increased to improve surface finish, then article formation is optimized, but plug stroke speed decreases
Solution Approach 1:
The segmented drive system with multiple independent roller screw shafts allows each plug to achieve optimal stroke speed for high surface finish, while the collective action of multiple shafts maintains high productivity. Each shaft can be optimized for precision without sacrificing overall system speed.
Solution Approach 2:
Multiple roller screw shafts are combined to provide both high speed and high forming pressure simultaneously. The merged system delivers the speed needed for surface finish optimization while generating sufficient collective torque for forming pressure, resolving the contradiction between precision and speed.
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 solution allows for the formation of articles with improved surface finish and reduced blemishes by increasing the speed and torque of plug advancement into the thermoformable web, maintaining lower web temperatures and minimizing cooling time, thus requiring less forming pressure and reducing undesirable surface defects.
Implementation Method 1
a first elongated gear rack, a second elongated gear rack, a drive gear, a driven gear, and a drive source. The first elongated gear rack and the second elongated gear rack are carried by the plug assist platen in longitudinally extending and substantially parallel, spaced apart relation with a plurality of rack teeth extending on each gear rack
Implementation Method 2
The drive gear is carried by the drive platen and is operably communicating with the first elongated gear rack. The driven gear is carried by the drive platen and is operably communicating with the second elongated gear rack and the drive gear
Implementation Method 3
a bevel gearbox, powered by a servo motor, enables quick movement of plugs into mold cavities with high forming pressures
Data Source
AI summary
A plug assist drive assembly is provided for a thermoforming press. The plug assist drive assembly includes a drive platen, a plug assist platen, a first elongated gear rack, a second elongated gear rack, a drive gear, a driven gear, and a drive source. The first elongated gear rack and the second elongated gear rack are carried by the plug assist platen in longitudinally extending and substantially parallel, spaced apart relation with a plurality of rack teeth extending on each gear rack between proximal and distal ends. The drive gear is carried by the drive platen and is operably communicating with the first elongated gear rack. The driven gear is carried by the drive platen and is operably communicating with the second elongated gear rack and the drive gear. The drive source is operably communicating with the drive gear to drive the assist platen in linearly reciprocating motion relative to the drive platen. A thermoforming machine having the plug assist drive assembly is also provided. A method is also provided.