Compression Moulding Rod Positioning for Small Orifice Tubes
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Solution Overview
Problem
Existing methods for producing plastic tubes with small diameters face issues such as inaccurate positioning of the orifice rod, leading to malformed heads, deformation, and breakage, especially when producing tubes with orifices less than 1.5 mm, resulting in unreliable production and frequent halts.
Innovation Solution
A device with non-elastic retaining means limits the bidirectional displacement of the orifice rod within the sleeve, ensuring precise positioning and preventing buckling, using a combination of stops and a pin or circlip to maintain the rod's position during the formation of the shoulder, allowing for controlled displacement and improved centring of the plastic material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the orifice rod is allowed to slide freely in the sleeve, then the rod can move during the forming process, but the positioning accuracy of the rod relative to the sleeve deteriorates, resulting in malformed heads and inconsistent orifice formation
Solution Approach 1:
The rod is designed with controlled mobility through non-elastic retaining means. The rod can move dynamically during the forming process to accommodate material flow, while the retaining means (stops and pin/circlip) ensure it returns to and maintains precise positioning, resolving the contradiction between movement capability and positioning accuracy.
Solution Approach 2:
The non-elastic retaining means act as an intermediary mechanism between the rod and sleeve. These retaining means allow controlled movement while preventing excessive displacement, serving as a mediator that enables both rod mobility and positioning precision simultaneously.
2Manufacturing precision
If the orifice rod is pushed back axially during head formation, then the orifice is formed in the shoulder, but the rod may buckle and break, especially for small diameter orifices less than 1.5 mm
Solution Approach 1:
The non-elastic retaining means provide beforehand cushioning by limiting the axial displacement of the rod. The stops and pin/circlip are positioned to prevent excessive compression of the rod before buckling can occur, cushioning the rod against forces that would cause structural failure during the orifice formation process.
Solution Approach 2:
The retaining means apply preliminary anti-action by opposing excessive axial compression of the rod. The non-elastic constraints create a counter-force that prevents the rod from reaching critical buckling loads, allowing safe orifice formation for small diameter rods.
3Ease of operation
If elastic retaining means such as springs are used to maintain rod position, then the rod can be retained in the upper position, but the positioning precision deteriorates due to the elastic nature of the retention
Solution Approach 1:
The non-elastic retaining means function as simple, reliable constraints that do not require complex elastic mechanisms. The stops and pin/circlip provide definitive positioning without the variability inherent in elastic materials, achieving precise rod positioning through simple mechanical constraints rather than complex spring systems.
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 enables reliable production of tubes with small orifices by maintaining precise rod positioning, reducing the risk of deformation and breakage, and improving the distribution of plastic material, resulting in higher quality and more efficient tube formation.
Implementation Method 1
a device for moulding a plastic article in which the article is obtained by the compression of a quantity of plastic material in the molten state between the two parts of a mould
Implementation Method 2
the quantity of material is deposited around a rod forming the orifice of the tube... a quantity of plastic material in annular form is deposited... The temperature of the material is such that it is welded to the body of the tube
Implementation Method 3
The temperature of the material is such that it is welded to the body of the tube
Data Source
AI summary
The invention relates to a device for moulding a plastic article in which the article is obtained by the compression of a quantity of plastic material (3) in the molten state between the two parts of a mould, comprising at least one supply of plastic material (1), a rod (11), sliding in a sleeve (8) suitable for temporarily supporting said quantity of plastic material (3), a mould for the head of the article (6, 7) and a mandrel (18) cooperating with said mould (6, 7), characterized in that it comprises non-elastic retaining means (12-14, 23, 24) which are suitable for limiting the bidirectional displacement of the rod (11) in the sleeve (8). The invention also relates to a method using the aforementioned device.