Injection Compression Mould Perimetral Ring Design
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Solution Overview
Problem
Existing injection-compression moulding technologies face issues with perimetral rings, including burr formation, high costs, difficult geometries, and uncontrolled movement leading to surface damage and visible junction lines, as well as challenges in ensuring tight closure and preventing piece ejection during mould opening.
Innovation Solution
A mould design featuring a perimetral ring with a convex polygonal interface profile that engages with the matrix and punch, using a hydraulic circuit for controlled movement, which prevents outward pressure, hides junction points, and ensures proper support and ejection control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a perimetral ring is used to ensure mould closing tolerances, then the required tolerances are achieved, but the pressure of molten material pushes the ring outward creating burrs on the piece
Solution Approach 1:
The perimetral ring is made movable along the axial direction rather than being fixed, allowing it to dynamically adjust its position during the moulding process. This enables the ring to accommodate material pressure while maintaining sealing, preventing burr formation while preserving tolerance control.
Solution Approach 2:
A hydraulic circuit is introduced as an intermediary system to control the movement of the perimetral ring. This mediator allows precise control of the ring's position and force application, balancing the need for tight closure with the prevention of material push-out and burr formation.
2Shape
If the perimetral ring follows geometrical features of the piece such as wings and ribs, then the piece geometry is accurately formed, but the construction becomes very expensive and creates difficult triple junction points
Solution Approach 1:
The perimetral ring is designed as a separate, modular component that can be independently manufactured and positioned. This segmentation allows the ring to define the profile without requiring complex integration with other mould components, simplifying construction while maintaining geometric accuracy.
Solution Approach 2:
The perimetral ring serves multiple functions: it ensures mould closing tolerances, defines the profile of the injection chamber, and accurately forms piece geometry. This multi-functionality eliminates the need for additional specialized components, reducing overall device complexity.
3Reliability
If the perimetral ring is held in position during closing, then tightness is ensured, but uncontrolled movement when opening the mould may damage the surface of the piece
Solution Approach 1:
The perimetral ring transitions from a fixed state during closing to a movable state during opening, allowing controlled movement that prevents surface damage. This dynamic behavior ensures tightness when needed while enabling safe extraction when required.
Solution Approach 2:
The hydraulic circuit provides feedback control of the perimetral ring's movement, allowing the system to respond to process conditions. This ensures the ring maintains position for tight closure while enabling controlled movement during opening to prevent surface damage.
4Shape
If the perimetral ring is used to define the profile of the injection chamber, then the profile is accurately formed, but visible junction lines appear on the piece
Solution Approach 1:
The function of defining the injection chamber profile is extracted and assigned specifically to the perimetral ring, separating this function from the matrix and punch. This allows the profile to be accurately formed while the ring's specific geometry can be designed to minimize or hide junction lines on the final piece.
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
The solution effectively prevents burr formation, hides junction lines, and ensures secure closure and controlled ejection of the piece during mould opening, enhancing the quality and aesthetics of the moulded parts.
Implementation Method 1
a hydraulic circuit (7) connected to said movement means (5)
Implementation Method 2
a perimetral ring (4) having a special shape of an interface wall with matrix (3) above, or with punch (2), wherein said perimetral ring (4) comprises a convex polygonal interface profile with matrix (3) above, or with punch (2)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A mould (1) for injection-compression moulding comprises a punch (2) and a matrix (3) suitable to close on the punch (2) so as to delimit with this an injection chamber (10) to contain the material to be injected, said matrix (3) and punch (2) being axially movable between them with respect to an axial direction (Y-Y) of opening/closing of the mould (1). The mould is further provided with a perimetral ring (4), slidingly associated to the punch (2) or the matrix (3), along the axial direction (Y-Y), suitable to define, together with the matrix (3) and the punch (2), the profile of the injection chamber (10). The mould is characterised in that the perimetral ring (4) comprises an interface profile (43), intended to engage with the matrix (3) or with the punch (2), equipped with a particular geometry suitable to generate, in the closing phase of the mould (1), a compression force of the ring (4) towards the inside of the mould (1).