| WO/2008/088642 | IMAGER ASSEMBLY AND METHOD FOR SOLID IMAGING |
| JP2001310918 | CURING COMPOSITION FOR PHOTOFORMING AND PRODUCT |
| JP58115404 | OPTICAL FIBER TERMINAL PROCESSOR |
SWOROBOWICZ, Grzegorz (ul. Cukrowa 16A/6, Wrocław, PL-51-316, PL)
JANKOWSKI, Piotr (ul. Cukrowa 15A/9, Wrocław, PL-51-316, PL)
SWOROBOWICZ, Grzegorz (ul. Cukrowa 16A/6, Wrocław, PL-51-316, PL)
| Claims 1. The method of smoothing prototype elements made using the SLS (Selective Laser Sintering) technology of materials based on polyamide powder - PA, wherein the element is subject to the effects of vapour of a chemical compound from the following group: formic acid, acetic acid, m-creozol, acetic anhydride, so that the applied chemical compound, in atmospheric pressure, is brought to a temperature above its specific boiling point for a time of 1-350 seconds, counting from the moment when vapours of the chemical compound condensate on the processed prototypical element. 2. The device for smoothing prototypical elements made using incremental technology SLS (Selective Laser Sintering) of materials based on polyamide powder - PA characterized in that the device (4) has a chamber (3) with working space, below which is: container of the active substance dispenser and heating element (6), separated from the working space with the movable screen (7), and vapour extraction system (8) with ventilation duct. |
The subject of the invention is a method and device for smoothing elements made using the SLS incremental technology (Selective Laser Sintering) of materials based on polyamide powder - PA.
Among numerous rapid prototyping technologies, some of the most commonly used are the incremental technologies SLS (Selective Laser Sintering); it is an incremental technology consisting in using laser beam to bond polyamide powder (PA), applied in layers on the model plate of the production machine. The depth of each applied layer of the polyamide powder is about 0,lmm-0,15mm.
Another widely used technology is FDM (Fused Deposition Modelling), an incremental technology consisting in laminar depositing of liquid thermoplastic plastic using a printing head on the pattern plate of the production device. The material is applied in layers the thickness of which is about 0,1mm to about 0,33mm.
Both these technologies are used to make a physical model directly from a digital solid 3D model.
Details made using these technologies have a characteristic surface texture. Depending on the technology applied, the surface is porous (SLS), or linearly constructed of material layers (FDM). In the case of the FDM technology, the laminar surface structure causes anisotropy of the constructed model.
Improving the surface of details made using incremental technologies grants numerous advantages. First of all, it enhances functionality of the model (particularly in the case of mated subassemblies), improves the visual effects, as well as decreases anisotropic properties of the detail, thus expanding its strength. Smoothing of the surface increases the resistance by homogenizing the surface layer.
Currently known and applied methods for improving the surface condition:
• Abrasive machining - mechanical.
• Abrasive machining - manual. • Surface abrasive machining by sand blasting.
• Infiltration (percolating the surface layer of the detail with another substance - usually resin - in order to smoothen it).
• Lacquering.
Another known method for surface smoothing, applied only in the case of details made using the FDM technology, is smoothing surface of models made of ABS plastic ((poli(acrylonitrile-co-butadiene-co-styrene))), consisting in effects of vapour of an appropriate chemical compound. This technology applies only to models made using the FDM (Fused Deposition Modeling) technology, of ABS material ((poli(acrylonitrile-co- butadiene-co-styrene))).
According to the invention, the method of surface smoothing consists in that the method of smoothing prototype elements made using the SLS (Selective Laser Sintering) technology of materials based on polyamide powder - PA, wherein the element is subject to the effects of vapour of a chemical compound from the following group: formic acid, acetic acid, m-creozol, acetic anhydride, so that the applied chemical compound, in atmospheric pressure, is brought to a temperature above its specific boiling point for a time of 1-350 seconds, from the moment when vapours of the chemical compound condensate on the processed prototypical element.
According to the invention, the device for smoothing prototypical elements made using incremental technology SLS (Selective Laser Sintering) of materials based- on polyamide powder - PA characterized in that the device 4 consists of chamber 3 with working space, below which is: container of the active substance dispenser and heating element 6, separated from the working space with the movable screen 7, and vapour extraction system 8 with ventilation duct.
The subject of the invention is presented in the drawing, in which fig.1 depicts the diagram of the smoothing device, and fig. 2 presents a chart of the obtained roughness parameter depending on the exposure time for control vertical tiles and control horizontal tiles. Design examples
Control tiles, in the size of 50mmx50rnmx5mm were made of PA2200 material based on polyamide powder (PA), using the SLS (Selective Laser Sintering) technology.
The tiles were made in two possible positions on the pattern plate of the SLS device, i.e. vertically (tiles marked as V) and horizontally (tiles marked as H). Position of the tile during forming of the same is of vital importance for the obtained surface condition of the raw model, especially its roughness.
The control tiles were subject to the process of smoothing and surface improvement, as per description above.
The smoothing process was carried out in the following conditions:
Applied active chemical compound: formic acid, Chemical formula: HCOOH,
Concentration: 85%
Boiling point: 100,7°C
Temperature of the vapour generator heating element: 300°C
Exposure time: 30 to 120 seconds
The samples were marked with the following symbols:
V0 - vertical plate without the process of surface smoothing and improvement, VI - vertical plate, exposure time 30 seconds,
V2 - vertical plate, exposure time 60 seconds,
V3 - vertical plate, exposure time 90 seconds,
V4 - vertical plate, exposure time 120 seconds,
HO - horizontal plate without the process of surface smoothing and improvement, HI - horizontal plate, exposure time 30 seconds,
H2 - horizontal plate, exposure time 60 seconds,
H3 - horizontal plate, exposure time 90 seconds,
H4 - horizontal plate, exposure time 120 seconds,
After completing the process, the plates were subject to roughness tests. Measurement results are presented in the table and charts below.
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