Crosshead Die Vertical Core Adjustment for Stable Parison Cutting
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Solution Overview
Problem
Conventional methods for cutting a parison into sheets face issues such as friction resistance, temperature control challenges, and complexity in design, leading to inefficient cutting and difficulty in varying sheet thickness, especially in blow molding processes.
Innovation Solution
A crosshead design featuring a core that moves vertically, with a first dividing body on separators in the lower portion and a second dividing body on the die, allowing the two to slide against each other for stable cutting, regardless of parison thickness, and enabling continuous variation in discharge port width for consistent sheet formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cutting blade is used to cut the parison after discharge, then the parison can be divided into sheets, but friction resistance increases and temperature control becomes difficult
Solution Approach 1:
The patent applies preliminary action by dividing the parison inside the crosshead before it is discharged. The dividing bodies are positioned within the crosshead to split the parison while it is still hot and pliable, eliminating the need for post-discharge cutting with blades that cause friction and temperature loss. This preliminary division action resolves the contradiction by achieving clean cuts without the harmful effects of external cutting mechanisms.
Solution Approach 2:
The patent replaces the conventional mechanical cutting blade system with a dividing body system that uses the extrusion process itself to create the separation. Instead of using a blade that mechanically cuts through the parison (causing friction), the dividing bodies guide the molten material to form separate streams directly from the die, substituting a friction-based mechanical cutting system with a flow-based division system.
2Adaptability or versatility
If the core is fixed and cannot move vertically, then the structure is simple, but the sheet thickness cannot be continuously varied
Solution Approach 1:
The patent applies dynamics by making the core movable in the vertical direction rather than fixed. The core can be positioned at different heights relative to the die, which directly controls the thickness of the extruded parison. This dynamic adjustment capability allows continuous variation of sheet thickness while keeping the overall structure relatively simple, as the movement is achieved through basic vertical positioning mechanisms.
3Adaptability or versatility
If the cutter projects from the core outer periphery, then cutting can be performed, but the cutter thickness cannot be increased to handle varying parison thicknesses
Solution Approach 1:
The patent applies preliminary action by performing the division action inside the crosshead before the parison exits. The dividing bodies are positioned within the crosshead interior, allowing them to act on the parison while it is still forming and has not yet acquired its final thickness. This enables the division mechanism to effectively handle varying parison thicknesses without requiring the cutter itself to be thick or adjustable, as the division occurs during the extrusion process rather than after.
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 smooth cutting of parisons without temperature drop, stable sheet formation across varying thicknesses, and simplifies the process by eliminating the need for cutting blades, allowing for efficient and clean sheet production using existing equipment with minimal modifications.
Implementation Method 1
a first dividing body provided on each of the separators is biased at all times toward a second dividing body, which is fixed to the die or core side, via a biasing body
Implementation Method 2
the first and second dividing bodies contact each other so as to be capable of sliding relative to each other in a vertical direction
Implementation Method 3
a radial direction width of the annular discharge port is varied by the vertical movement of the core, and the parison is cut by the separators even when a thickness of the parison is varied
Data Source
AI summary
An object of the present invention is to form a pair of sheets by bisecting a parison using a first dividing body of a separator provided in a lower portion of a core or a die, and a second dividing body provided on the die or the core. In a crosshead according to the present invention, a pair of sheets (7) are formed by bisecting a parison (3) suspended from a resin flow passage (30) formed between a core (9) and a die (8) by causing a first dividing body (33) of a separator (5, 5a) provided on the core (9) or the die (8) to contact a second dividing body (40) provided on the core (9) or the die (8) .