Rotational Moulding Device with Independent Heating and Cooling Chambers
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Solution Overview
Problem
Current rotational molding machines face challenges with complex and costly mold production, long cycle times, non-uniform temperature distribution, and humidity issues that affect the quality of molded parts, particularly in polyurethane production.
Innovation Solution
A mold device with independent heating and cooling systems using separate chambers for steam and cold water, allowing for rapid and uniform temperature control, reducing thermal inertia and enabling quick adaptation to different part shapes without the need for extensive mold modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heating and cooling coils are integrated into the mold walls, then temperature control is achieved, but the mold becomes complex and expensive to manufacture and modify
Solution Approach 1:
The invention separates the mold into two independent half-shells that can be assembled and disassembled. The heating and cooling coils are integrated into these modular half-shells rather than being permanently embedded in a monolithic mold structure, allowing for easier manufacturing, modification, and maintenance while achieving effective temperature control.
2Temperature
If heating and cooling coils are integrated into the mold walls, then temperature control is achieved, but cycle times remain too long due to high thermal inertia
Solution Approach 1:
The mold design allows for dynamic adjustment of thermal parameters by enabling quick exchange of the half-shell components. The separation into movable half-shells with integrated coils allows for optimized thermal response and reduced thermal inertia compared to traditional integrated mold designs, thereby reducing cycle times and improving productivity.
3Temperature
If external sprayers are used for cooling, then cooling is achieved, but humidity increases which is detrimental to polyurethane quality
Solution Approach 1:
The invention extracts the cooling function from external sprayers that introduce humidity into the environment and integrates it directly into the mold structure through cooling coils embedded in the half-shells. This internal cooling system achieves effective temperature reduction without exposing the polyurethane material to humid atmospheric conditions that would compromise quality.
4Device complexity
If the same fluid circuit is used for both heating and cooling, then device complexity is reduced, but heating and cooling efficiency decrease due to thermal inertia
Solution Approach 1:
The fluid circuit is segmented into separate heating and cooling circuits, each with its own fluid flow path. This segmentation allows independent optimization of heating and cooling operations, eliminating the thermal inertia problems associated with using a single shared circuit, while the modular half-shell design keeps the overall system manageable and not excessively complex.
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 rapid heating and cooling cycles, improves temperature uniformity, reduces cycle times, and prevents humidity-related defects, making it suitable for both thermoplastic and thermosetting materials while minimizing costs and production complexity.
Implementation Method 1
first means (14, 15, 16) for sending inside the chambers a current of a heating fluid to heat the cavities (8)
Implementation Method 2
second means (17, 18, 19, 20) for sending inside the chambers a current of a cooling fluid to cool the cavities, possibly to spray the fluid cooling on the cavities (8)
Data Source
Figure 1~4
AI summary
The invention relates to a mould device for a machine for the rotational moulding of a part, that comprises two upper (1) and lower half-tanks, each of said half-tanks being defined by one or more walls (2, 3), wherein the lower (4) and upper inner edges of each half-tank receive a cavity-carrying plate(s) (5) on which are attached one or more upper (8) and lower cavities, the inner surface (10) of the upper (8) and lower cavities defining one or more moulds (11) having a shape corresponding to that of the part(s) to be moulded, and the outer surface (12) of the upper cavity or cavities (8) and of the lower cavity or cavities defining, together with the wall(s) (2, 3) of the upper (1) and lower half-tanks, upper (13) and lower closed chambers. Means (14, 15, 16) are provided for feeding a fluid stream inside the chambers in order to heat the cavities (8), and means (17, 18, 19, 20) different from the means (14, 15, 16) are provided for feeding a fluid stream inside the chambers for cooling the cavities, while means (21, 22, 23) different from the means (14, 15, 16) and (17, 18, 19, 20) are provided for discharging the heating and cooling fluids.