Rotational Mould Venting With a Cooled Shutter Against Polymer Adhesion
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Solution Overview
Problem
Existing rotational moulding processes require frequent and time-consuming manual cleaning of the venting device shutter due to polymeric material adhesion, leading to machine downtime and increased production costs.
Innovation Solution
The shutter of the venting device is kept relatively cold during the initial heating phase to prevent polymeric material adhesion, using an air flow to cool the shutter and maintain it at a lower temperature, and the main body of the venting device is also cooled to prevent overheating, thereby reducing material accumulation and potential damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the venting device shutter is heated during the mould heating phase, then the polymeric material melts and can be vented, but the polymeric material adheres to the shutter surface requiring frequent cleaning
Solution Approach 1:
The venting device is segmented into a main body and a shutter that can be independently temperature-controlled. The shutter is cooled separately from the main body through a dedicated cooling channel, allowing differential temperature management that prevents material adhesion on the shutter while maintaining venting capability.
Solution Approach 2:
Different parts of the venting device are maintained at different temperatures. The shutter is kept at a lower temperature than the main body through localized cooling, creating a temperature gradient that prevents polymeric material adhesion on the shutter surface while allowing the main body to function properly.
2Loss of time
If the shutter is kept cold to prevent material adhesion, then cleaning frequency is reduced, but the venting capability may be compromised
Solution Approach 1:
The shutter is made dynamically controllable through an actuator that can move it between open and closed positions. This dynamic control allows the shutter to be open for venting when needed and closed to prevent material adhesion, with the cooling system actively maintaining low temperature during the closed position.
Solution Approach 2:
The shutter is pre-cooled before the polymeric material is introduced and throughout the molding process. This preliminary cooling action prevents material adhesion from occurring in the first place, eliminating the need for subsequent cleaning operations.
3Reliability
If the main body of the venting device is heated, then gases can be vented from the cavity, but the venting device may overheat causing damage
Solution Approach 1:
The harmful heat is extracted from the venting device main body through a dedicated cooling channel that runs through the main body. This cooling channel allows heat to be removed from the main body, preventing overheating and potential damage while still allowing the venting function to operate.
Solution Approach 2:
The temperature parameters of the venting device are actively controlled and changed during the process. The main body temperature is regulated through the cooling channel to maintain it within safe operating limits, preventing thermal damage while enabling effective venting.
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 approach minimizes the need for frequent cleaning, reduces machine downtime, and lowers production costs by preventing shutter malfunctions and material adhesion, thus enhancing process efficiency.
Implementation Method 1
an air flow to cool the shutter and maintain it at a lower temperature
Implementation Method 2
the main body of the venting device is also cooled to prevent overheating
Data Source
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AI summary
Rotational moulding process for producing an article (300), the process comprising: - providing a mould (100) comprising: - a main body (99) which defines an inner cavity (30) having a conformation surface (31) counter-shaped to the article (300), and - a venting device (1) fixed to the main body (99) and comprising: - an inner chamber (2) in air communication with the inner cavity (30) through a first mouth (3) and with an outer environment (35) through at least one second mouth (4); - a shutter (5) movable between an open position, in which let free the first mouth (3) for putting the inner cavity (30) in air communication with the outer environment (35), and a close position, in which closes the first mouth (3) for preventing the air communication; - an actuator (6) for alternately moving the shutter (5) between the open position and the close position, the process further comprising: - inserting a fluid form polymeric material into the inner cavity (30); - closing the main body (99) and rotating the mould (100); - while keeping the mould (100) in rotation and with the shutter (5) in the close position, heating the main body (99) until reaching a first temperature; - while keeping the mould (100) in rotation, heating the main body (99) until reaching a second temperature higher than the first temperature; - cooling the main body (99) and extracting the article (300), and wherein, during the heating of the main body (99) until the reaching of the first temperature, the process further comprises subtracting heat from the shutter (5) for maintaining the shutter (5) at a respective temperature lower than the first temperature.