雷射燒結變質層層厚控制技術

Property Transformation Thickness Control of Laser Sintering

林政毅(Cheng-Yi Lin)

指導教授 ： 湯華興

國立臺北科技大學/機電學院/製造科技研究所/碩士(2006年)

https://doi.org/10.6841/NTUT.2006.00295

摘要

本文針對陶殼模快速原型機製程研製控制-繪圖機+雷射-的關鍵技術，目的為獲得一致性變質層厚度的技術，期望製程品之精度可達到精密鑄造的品質要求。
新開發的雷射功率回饋控制系統與生坯表面溫度監視系統，可自動量測並補償雷射功率與量測生坯表面溫度，使雷射輸出功率與生坯工作表面溫度能夠穩定一致，有效提升工件品質穩定度。自主開發之點陣掃描程式，能使雷射避開加減速區，在等速區時才開啟掃描，使工件得到相同的能量密度。研究開發的PWM雷射控制器可用來量測XY-Plotter (XY繪圖機)加、減速區之長度，有助於獲得更精確之掃描參數值，有助於點陣掃描程式與控制系統的整合。
為克服XY-Plotter向量掃描時的馬達加速度值過慢與速度值的不穩定，而開發雷射單軸控制器整合到雷射掃描平台，將伺服馬達的光學編碼器(encoder)的讀數輸送至單晶片上，用以計數馬達所移動的距離。計數達到所設定的數值後，雷射控制器就輸出單一方波脈衝，用以驅動雷射激發，以確保在雷射掃描路徑上，雷射擊發之落點都能保持相同距離。實際測試證實路徑上能量密度為均勻分佈。

關鍵字

變質層 ； 雷射功率 ； 能量密度 ； 雷射控制器 ； 生坯表面溫度 ； 向量掃描

並列摘要

The aim of this study is to develop a key technique of laser and scanning mechanism controlling in order to obtain a uniform property transformation depth, which leads to achieve the accuracy of precision casting.
For raising the quality of workpiece, a laser power feedback control system which could measure and compensate laser power, and a monitoring system which could measure the green part surface temperature were developed to obtain stable laser power and green part surface temperature. A self-developed raster scanning program could make laser scanning started at zone with constant scanning speed; therefore, workpiece could obtain uniform power density. The developed PWM laser controller was used for measure the length of accelerating a decelerating zone of X-Y scanning mechanism; it was helpful to achieve more accuracy scanning parameters and to integrate the raster scanning program to control system.
A single axis controller was developed and integrated to laser scanning platform for solving the problems of accelerating too slow and velocity unstable. Data from servo motor optical encoder was transmitted to a single chip for counting the motor moving distance. When the number of counting reached the preset value, laser controller would output a single square wave pulse for launch the laser; therefore, distance between each laser spot would be kept in constant. As a result, the power density was uniform distribution along the scanning path.

並列關鍵字

Property transformation depth ； Laser power ； Laser controller ； Surface temperature of green part ； Vector scanning

參考文獻

[1] H. H. Tang, “Method for rapid forming of a ceramic work piece,”. U.S. patent no. 6217816, 2001.

[10] 陳皇印，陶瓷雷射快速原型製程優化與應用，碩士論文，國立台北科技大學製造科技研究所，台北、台灣，2006。

[13] Rahaman,M.N., “Ceramic Processing and Sintering,”M.Dekker,New York,1995.

[14] H. H. Tang, ”Direct laser fusing to form ceramic parts”, Rapid Prototyping Journal, vol. 8, no. 5, 2002, pp.284-289.

[2] H. H. Tang and F.H. Liu, et al, ”Ceramic Laser Fusion,” Journal of Tsinghua University (Science and Technology), vol.42, no. s2, 2002, pp.209-212.