Additive Manufacturing Heating Surface for Uniform Powder Bed Temperature
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Solution Overview
Problem
Existing additive manufacturing methods face challenges in achieving uniform temperature distribution over the powder surface, leading to temperature differences and unpredictable physical characteristics in the manufactured solid articles.
Innovation Solution
A device with a heating surface that is transmissive to the laser beam, using transparent conductive oxides, nanowires, or nanotubes, and a multi-zone heating system to maintain a consistent temperature across the powder surface, ensuring precise temperature control and uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional heating device is used to heat the powder surface, then thermal energy can be supplied to the powder, but uniform temperature distribution cannot be achieved leading to temperature differences up to 15°C
Solution Approach 1:
The heating device is divided into multiple heating zones (first heating zone, second heating zone, third heating zone) that can be independently controlled. Each zone targets specific areas of the powder bed to compensate for heat loss patterns, with outer zones providing higher power to edge areas and inner zones adjusting accordingly, achieving uniform temperature distribution across the entire powder surface.
Solution Approach 2:
Different heating zones are assigned different power levels based on local thermal requirements. The outer heating zones operate at higher power to compensate for greater heat loss at edges, while inner zones operate at lower power. This localized quality adjustment ensures uniform temperature distribution across the powder bed, preventing the temperature differences that lead to warpage and dimensional inaccuracies.
2Productivity
If laser beam is used to selectively sinter the powder, then the solid article can be manufactured, but thermal stress and warpage occur due to uneven cooling
Solution Approach 1:
The heating device pre-heats the entire powder bed before and during the laser sintering process. This preliminary heating action ensures that the powder is at a uniform temperature prior to selective sintering, and maintains temperature during the process. This prevents thermal gradients and uneven cooling that cause warpage and structural instability, while allowing the laser to operate at high speed for efficient manufacturing.
Solution Approach 2:
The heating device applies counter-heating to offset the cooling effect that occurs during and after laser sintering. By maintaining the powder bed temperature through continuous or intermittent heating, the system prevents the thermal stress and warpage that would otherwise occur during cooling, ensuring structural stability of the manufactured article.
3Productivity
If the laser power is increased to reduce manufacturing time, then productivity improves, but thermal stress and warpage increase
Solution Approach 1:
The system uses temperature sensors to continuously monitor the powder bed temperature and feeds this information back to the heating device controller. Based on the feedback, the heating zones adjust their power output in real-time to maintain uniform temperature distribution. This allows the laser to operate at high power for fast manufacturing while the heating device compensates to prevent thermal stress and warpage, maintaining dimensional accuracy.
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 achieves a temperature variation of less than ±1°C across the powder surface, improving the quality and predictability of the solid articles by reducing thermal stress and warpage, and eliminating the need for individual testing to meet specifications.
Implementation Method 1
The heating device includes a heating surface to provide thermal energy to a raw material surface to form a pre-heated raw material surface
Implementation Method 2
A laser beam generated by a laser generation unit passes through the heating surface onto the pre-heated raw material surface such that a first solid layer portion of the solid article is obtained when directing the laser beam onto the pre-heated raw material surface
Implementation Method 3
The heating surface contains at least one of the elements of the group of a transparent conductive oxide, of a network of nanowires or of nanotubes
Data Source
Figure 1
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AI summary
An additive manufacturing device (1) for manufacturing a solid article comprises a laser generation unit (3), a raw material supply unit (4), a raw material container (5) containing a raw material (6) and having a raw material surface (7) exposed to a laser beam (8) to be emitted by the laser generation unit (3) in operation and a control unit (9). The heating device (2) includes a heating surface (12) for heating the raw material surface (7) to form a pre-heated raw material surface (17). The laser generation unit (3) is disposed with a directing unit (13) to direct the laser beam (8) onto the pre-heated raw material surface (17) according to a computer generated model of the solid article (10) stored in a storage unit (11) associated with the control unit (9). The laser beam (8) generated by the laser generation unit (3) passes through the heating surface (12) onto the pre-heated raw material surface (17).