1232786 (1) 玖、發明說明 【發明所屬之技術領域】 本發明相關於三維燒結製品的製造方法，其中目標物 體是藉著以一光束來燒結及硬化粉末材料層而獲得，本發 明特別相關於藉著結合由被雷射射束燒結的金屬粉末層製 成的多個疊層來製備金屬模的方法。 【先前技術】 曰本專利第26203 5 3號揭示被稱爲光成形（photoshaping ) 的三 維物體 的製造 方法。 根據此 專利案 ，一光 束L先照射在由可爲有機材料或無機材料的粉末材料構成 的粉末材料層的預定部份上，以形成一燒結層。然後，如 此獲得的燒結層被一新的粉末材料層覆蓋，並且光束L照 射在新的層的預定部份上，以形成與下方層結合的新的燒 結層。這些步驟被重複地執行來形成燒結製品或三維物 體’其中多個燒結層被一個在另一個之上地穩固地層疊。 根據此方法，光束L的照射是根據每一層的截面形式資料 (sectional form data )而進行，而資料係藉著將三維物 體的設計資料（CAD資料）的模型切塊成爲想要的厚度 而獲得。因此，與傳統的切割及機械加工方法相比，在沒 有CAM裝置下，上述的方法可被用來快速地製造任意形 狀的三維物體以及獲得具有想要的形狀的任何形狀的物 體。 但是’根據此方法，在考慮諸如由於模製時間及內部 -5- 1232786 (2) 應力所造成的翹曲及破裂等問題之下，此方法應藉著將必 要部份燒結成爲較高密度且將其餘部份燒結成爲較低密度 而被執行，而非藉著將所有的部份燒結成爲相同的密度來 執行。例如，在射出成形用的金屬模的情況中，用於物體 的複製（transcription)的表面部份及用於冷卻水的管路 部份應以較高密度形成，而其餘部份應以較低密度形成。 較高密度燒結層由於幾乎完全的熔化及固化而具有非 常平滑的完工表面，因而保持冷卻水管路的不透水性。但 是，具有50%至60%的密度的粉末材料層會被燒結成爲具 有幾乎100%的密度的較高密度層，使得如圖16所示，當 具有tG的厚度的粉末材料層10會藉著光學照射而被燒結 成爲較高密度層1 1 Η時，較高密度層的表面位準會從粉 末材料層的原始表面位準降低一段差異5。 另外，當粉末材料層的厚度是由載台20的下沈量 (sinking amount)決定時，粉末材料層的厚度被設定於 比預定値t大的値，並且另外，當粉末材料層1〇會藉著 較高密度的燒結條件而被燒結時，所得的較高密度層的表 面會降低一段載台差異(差異<5a大於差異δ)。 另外，另一粉末材料層1 〇形成在較高密度層1 1上， 且在用於較低密度的條件下被燒結而形成較低密度層 1 1 L。如圖1 8所示，粉末材料層1 0在此情況中會以上述 的差異（5a變得較厚。 在此方法中，因爲用於較低密度的光束條件是根據粉 末材料層1 〇的預定厚度t被決定，所以具有預定條件的 -6 - 1232786 (3) 光束不能使粉末材料比完全燒結的預定厚度t厚一段差異 (5 a ’医I而並未給予所得的較低密度層足夠的黏著力 (adhesive power )，使得較低密度層易於從較高密度層 剝離。 【發明內容】 本發明已被開發來克服上述的不利點。 因此’本發明的一目的爲提供一種創新的可製造三維 火堯，結製品的方法’其在較高密度層與較低密度層之間提供 良好的黏著。 本發明的另一目的爲提供上述類型的方法，其可製備 具有在用於較低密度層的預定條件下完全燒結的較低密度 層的三維燒結製品。 在達成上述及其他目的時，從本發明的第一方面，提 供一種三維燒結製品的製備方法，其包含的步驟爲（a ) 藉著一第一光束的照射來燒結一第一粉末材料層的一預定 部份’以形成具有一較高密度的第一層，（b)在該第一 層上形成一第二粉末材料層，（c )藉著一第二光束的照 射來燒結該第二粉末材料層的一預定部份，以形成具有一 較低密度的第二層以及將該第二較低密度層結合於該第一 較高密度層，及（d)重複步驟（a)至（c)來形成包含 多個該第一及第二層的三維燒結塊件， 其中具有低密度的該第二燒結層是經由具有在該第一 燒結層的高密度與該第二燒結層的低密度之間的一中間密 1232786 (4) 度的一附加燒結層而形成在具有高密度的該第一燒結層 上。 根據本發明的第一特徵，具有較低密度的第二燒結層 並非直接而是經由具有中間密度的附加層形成在具有較高 密度的第一燒結層上，使得較高密度層與較低密度層之間 的黏結力可由於從較高密度至較低密度的循序改變以及不 形成任何具有不足的較低密度的燒結層而不會變弱。 在此方法中，具有中間密度的附加燒結層可包含多個 層，其中每一層的密度與離開較高密度層的距離成比例地 減小。中間密度層中密度的平滑改變可形成從較高密度層 至較低密度層的特性的平滑改變。在此情況中，合適的燒 結條件應根據要被燒結的粉末材料層的厚度被決定，使得 中間密度層可在合適的燒結條件中形成。 從本發明的第二方面，提供一種三維燒結製品的製備 方法’該三維燒結製品包含藉著一光束的照射在粉末材料 層的預定部份上而燒結的較高密度層及較低密度層，其中 在至少最上方較高密度層上的用於較低密度層的一粉末材 料層形成爲厚度比一通常的預定値小且承受根據較低密度 層的燒結條件的燒結過程。 根據本發明的第二特徵，用於較低密度層的粉末材料 形成爲具有用於燒結的合適厚度的層。因此，如果較高密 度層形成爲比一預定値小，則下一粉末材料層永遠被設定 爲具有用於預定的燒結條件的合適厚度，使得所得的較低 密度層具有良好的黏著性。 -8 - 1232786 (5) 從本發明的第三方面，提供一種三維燒結製品的製備 方法，該三維燒結製品包含藉著一光束的照射在粉末材料 層的預定部份上而燒結的較高密度層及較低密度層，其中 在至少最上方較高密度層上的用於較高密度層的一粉末材 料層形成爲厚度比一通常的預定値小且承受根據較低密度 層的燒結條件的燒結過程。 根據本發明的第三特徵，一附加較高密度層形成來調 整用於較低密度層的形成位置，即使是較高密度層形成爲 比預定値小，使得用於低密度層的下一粉末材料層被控制 成爲具有用於燒結的合適厚度，因而形成具有良好黏著性 的較低密度層。 在此方法中，粉末材料層的厚度可藉著供所得的層被 定位的載台的一下沈量而被決定，並且下一粉末材料層形 成在所得的層上。附加的較高密度層可在載台沒有任何下 沈量之下形成。在此情況中，可減少使載台下沈的操作時 間。 當較低密度層形成在較高密度層上時，粉末材料層的 厚度及燒結條件可藉著已經形成的製品高度及/或用來使 粉末材料層均平的刀片的驅動負荷的測量結果而被決定。 根據此方法，可確實地避免用於較低密度層的粉末材料有 過量的厚度。 根據本發明的第四方面，當較低密度層形成在較高密 度層上時，較高密度層形成爲厚度比一預定値大，然後被 削除至預定厚度。因此，用於較低密度層的粉末材料的厚 -9 - 1232786 (6) 度可在被定位於預定高度處的較高密度層的表面上被設定 於預定値，使得粉末材料層可藉著具有合適條件的光束而 被燒結，屆時可避免形成不良黏著性的較低密度層。 如上所述，根據本發明，用於較低密度層的粉末材料 的厚度可藉著中間密度層的存在，用於較低密度層的粉末 材料的厚度的控制，及附加較高密度層的形成而被控制成 爲不大於一預定値，使得不良黏著性的較低密度層的形成 以及較高密度層與較低密度層之間的分離可被避免。 本發明的以上及其他目的及特徵會從以下參考圖式的 本發明的較佳實施例的敘述而更爲顯明，在圖式中相同的 部份由相同的參考數字標示。 【實施方式】 本案係根據分別於2002年9月30日及2003年7月 28日於日本申請的申請案第 2002-2 8 77 68號及第 2003 -2 8 1 25 9號，其內容藉著參考整個明確地結合於此。 在本發明的方法中，可使用不同種類的設備來製造三 維燒結製品。現在參考圖式，在執行圖中所示的實施例的 設備中，上下移動的載台20被定位在一模製槽25中。粉 末材料被供應至載台20上，以藉著擠壓刀片（squeezing blade )而形成具有預定厚度的粉末材料層10。然後，粉 末材料層的一預定部份被由掃描光學系統操作的光束（雷 射射束）L照射而形成燒結層1 1。 用來照射光束的光束系統設置有用來改變掃描節距及 -10- 1232786 (7) 掃描速率的控制機構。較高密度燒結層可藉著具有較小掃 描節距及較慢掃描速率的高燒結條件來形成。另一方面， 較低密度燒結層可藉著具有較大掃描節距及較快掃描速率 的低燒結條件來形成。當然，光束的輸出可根據預定的控 制排程被改變。 詳細地說’圖13顯不根據本發明的第一實施例的用 來製造三維物體的設備。圖中所示的設備包含用來形成粉 末層10的粉末層形成單元2，用來形成燒結層11的燒結 層形成單元3’及用來移除低密度表面層的表面層移除單 元4。粉末層形成單元2形成具有想要的厚度Δί1的粉末 層1 〇，此係藉著將有機或無機粉末材料供應至在由一圓 筒環繞的空間內直立移動的燒結台2 0上，以及藉著用校 平刀片2 1來校平粉末材料。燒結台2〇由驅動單元5驅動 以上下移動。燒結層形成單元3藉著經由包含偏轉板 (deflector ) 3 1及類似者的掃描光學系統將從雷射射束產 生器3 0射出的雷射照射在粉末層1 〇上來形成燒結層 1 1。一雷射振盪器較佳地被使用成爲雷射射束產生器 30。表面層移除單元4包含安裝在其底座上的χγ驅動單 兀40，及安裝在ΧΥ驅動單元4〇上的完工機（finishing machine) 41。XY驅動單元4〇以被線性馬達用高速驅動 較佳。一鍍鋅鏡較佳地被使用成爲偏轉板3 1。一切割機 例如端銑刀或鑽床，一雷射射束機，或用來藉著對物體吹 送燒結粉末而相對於物體執行塑性加工（plastic working)的一*噴砂機（blasting machine)較佳地被使用 -11 - 1232786 (8) 成爲完工機41。一極座標驅動單元可被用來取代XY驅動 單元40。 圖Π顯示如何使用上述的設備來製造三維物體。如 圖所示，有機或無機粉末材料首先被供應至安裝在燒結台 2 0上的底座2 2上，其被採用成爲用來調節燒結層形成單 元3與燒結層之間的距離的距離調節器。然後，供應至底 座22上的粉末材料被校平刀片21校平而形成第一粉末層 1 〇，並且光束（雷射射束）L照射在第一粉末層1 〇的想 要的部份上以將其燒結，因而形成與底座22結合的燒結 層1 1。 然後，燒結台20下降一預定長度，並且一第二粉末 層1 〇藉著再次地供應粉末材料及藉著使用校平刀片2 1將 其校平而形成。光束L再次地照射在第二粉末層1 〇的想 要的部份上來將其燒結，因而形成與下方燒結層1 1結合 的另一燒結層1 1。 在燒結台2 0下降之後形成新的粉末層1 〇的過程及將 光束L照射在新的粉末層1 〇的想要的部份上以形成新的 燒結層1 1的過程被重複地執行，因而製造三維物體。具 有大約20 μχη (微米）的平均直徑的大致球形的鐵粉末粒 子較佳地被用爲粉末材料，並且c〇2雷射較佳地被使用成 爲光束。每一粉末層10的較佳厚度Δί1爲大約〇〇5mm (毫米）。 圖1 2 τκ意地顯示根據本發明的資料流程的例子。此 資料流程使想要的三維CAD模型具有兩種資料，亦即指 -12- 1232786 (9) 示雷射照射路徑的資料及指示切割路徑的資料。這些路徑 是從預先被設計的三維C A D資料準備，以指示想要的形 狀。 雷射照射路徑與傳統成形方法中大致相同，其中目標 形狀是由已經藉著於相等節距（在此實施例中爲 0.05mm)處將從三維CAD模型產生的STL資料切塊而獲 得的用於每一區段的輪廓資料來界定。輪廓資料被附加上 雷射照射條件（掃描速率，點直徑，功率，及類似者）來 產生新的資料，而新的資料又被送至完工處理過程。 切割路徑爲在考慮要被用在三維CAM中的完工工具 的直徑，種類，進刀率，旋轉速率等之下獲得的路徑。指 示此路徑的資料也被送至完工處理過程。 指示雷射照射路徑的資料被用在雷射燒結過程中，而 指示切割路徑的資料被用在高速切割過程中。此二過程被 重複地執行而完成目標形狀。 光束的照射以被實施成爲使得三維物體的至少表面區 域被燒結成爲具有高密度（例如小於5 %的孔隙度）較 佳。其原因在於即使是表面層被表面層移除單元4移除， 而如果表面區域具有低密度，則在表面移除過程之後曝露 的表面仍然爲多孔狀。因此，如圖1 4所示，模型資料被 分成用於表面區域S的模型資料及用於內部區域N的模 型資料，並且光束在大部份的粉末材料熔化時內部區域N 成爲多孔狀而表面區域S成爲具有高密度的條件下照射。 在圖15A中，參考數字12標示高密度區域，並且參 -13- 1232786 (10) 考數字1 6標示如以上所討論的藉著粉末材料的黏著而產 生的低密度表面層。位在高密度區域1 2內側的內部部份 具有比高密度區域1 2的密度低但是比低密度表面層1 6的 密度高的密度。 在多個燒結層1 1的形成期間，當其總厚度達到從例 如銑刀頭（milling head) 41的工具長度決定的一特定値 時，表面層移除單元4被啓動來切割當時已經成形的三維 物體的表面。例如，具有1 m m的直徑及3 m m的有效刀片 長度的銑刀頭41的工具（圓頭槽銑刀（ball end mill )) 可達成深度3 mm的切割。因此，如果粉末層1 0的厚度△ tl爲0.05mm，則表面層移除單元4在已經形成六十個燒 結層1 1時被啓動。 如圖15A所示，此種表面層移除單元4可移除藉著 粉末的黏著於成形物體的表面而產生的低密度表面層 1 6，並且可同時切除高密度區域丨2的一部份，因而使高 密度區域1 2曝露在成形物體的整個表面上，如圖〗5 b所 示。爲此目的，燒結層1 1的形狀形成爲比想要的形狀Μ 的尺寸稍大的尺寸。 舉例而言，當光束L在以下所給的條件下沿著想要的 輪廓線照射時，每一燒結層1 1的水平尺寸（寬度）成爲 比想要的形狀]VI的尺寸大大約0.3 m m。 雷射功率：200W (瓦特） 雷射點直徑：0.6 m m 掃描速率：50mm/s (毫米/秒） -14 - 1232786 (11) 於直立方向的過量厚度可以與於水平方向的過量厚度 相等或不同。燒結層1 1的形狀的直立尺寸是藉著修改指 示想要的形狀Μ的直立尺寸的原始資料而獲得。在切割 是使用具有1 mm的直徑的圓頭槽銑刀來執行的情況中， 工具的切割深度，進刀率，及旋轉速率以分別被設定於 〇·1 至 0 · 5 mm，5 至 5 0 m/m i η (公尺 /分鐘），及 20000 至 1 OOOOOrpm 較佳。 例子 如圖1所示，在載台20上，藉著例如200W的雷射 功率，0.2mm的掃描節距，及50mm/Sec的掃描速率的高 密度燒結條件形成有二較高密度燒結層1 1 Η，1 1 Η。然 後，中間層1 1 Μ藉著在例如2 0 0 W的雷射功率，〇 . 3 mm的 掃描節距，及1 〇〇mm/sec的掃描速率的中間密度燒結條件 下的光束L而形成，然後較低密度層11L藉著在例如 200W的雷射功率，〇.5mm的掃描節距，及3 00mm/sec的 掃描速率的低密度燒結條件下的光束而形成。在此例子 中，即使是粉末材料層1 0具有比用於較低密度燒結條件 的厚度大的厚度，中間密度燒結條件也足以使具有較大厚 度的粉末材料層被完全燒結，因而可避免中間密度層1 1 Μ 與較高密度層1 1 Η之間的分離。 如圖2所示，中間層可包含多個層llMa，11Mb，及 1 1 Me，其燒結條件根據至較低密度層的距離而減小。例 如，較靠近較高密度層1 1 Η的中間密度層1 1 Ma會被設定 -15- 1232786 (12) 於例如 2 00W的雷射功率，〇.3mm的掃描| 1 OOmm/sec的掃描速率的燒結條件，且中間密虔 會被設定於例如200W的雷射功率，〇.35mm 距，及1 5 0 m m / s e c的掃描速率的燒結條件，而較 密度層1 1 L的中間密度層1 1 M c會被設定於例如 雷射功率，0.4mm的掃描節距，及200mm/sec的 的燒結條件。取代此條件，在與較低密度燒結條 功率及掃描節距相同的條件下，掃描速率可被控 著層的越靠近較低密度層越高。 如圖3所示，在較高密度層形成之後，粉末 較高密度層之間的差異5 a可由用來測量高度的; 量，並且下一粉末材料層的厚度（t+ 5a)也被 時用於中間密度層1 1 Μ的燒結條件可根據測量 定。用於中間密度層的合適條件可根據實驗資料 決定。 另外，如圖4所示，當較低密度層1 1 L形成 度層11Η上時，載台20的下沈量（包括零）可 比一預定値t小的値，因而給予下一粉末層在低 條件下的用於較低密度層1〗L的合適厚度。 另外’如圖5所示，爲抵銷在粉末材料層] 密度層1 1 Η之間的差異5 a，在燒結較高密度層 台不降低或是降低得比預定値t小，並且粉末材 來充塡空間。在此情況下，一附加較高密度層 成來抵銷差異’然後一較低密度層可在較低密度 范距，及 :層 11Mb 的掃描節 靠近較低 200W 的 掃描速率 件的雷射 制成爲隨 材料層與 深針P測 測量，屆 結果被決 等被預先 在較高密 被設定於 密度燒結 .〇與較高 之後，載 料被供應 1 1 Η ’被形 燒結條件 -16- 1232786 (13) 下形成。在較大差異的情況中，多個附加較高密度層可根 據上述的程序被形成。附加較高密度層的厚度可逐漸地變 薄，且最後一較低密度層會被形成。在圖5中，2 1標示 擠壓刀片。 另外，如圖6A所示，當粉末層10與較高密度層11H 之間的差異被測量時，下一步驟可根據測量結果從以下的 步驟來選擇’亦即步驟（a) —較低密度層11L在附加較 高密度層1 1 H’的形成之後形成，或（b ) —較低密度層 11L在沒有附加層11H5之下直接形成在較高密度層11H 上。在較大差異a的情況中，如圖6B所示，一粉末材 料層在載台20沒有任何下沈之下形成，並且此粉末材料 層被燒結成爲較高密度層1 1 Η ’來使差異較小。在較小差 異δ a的情況中，載台20下降，粉末材料被供應，並且 較低密度層1 1 L被形成。 如圖7所示，差異（5a可藉著被用來使粉末材料均平 的刀片2 1的驅動負荷F而被測量。在等於圖7 A所示白勺 大差異的較小負荷F的情況中，下一粉末材料層在載台 2 0沒有任何下沈量之下形成。在等於圖7 B所示的小差異 的較大負荷F的情況中，下一粉末材料層在載台20有某 一下沈量之下形成。 如圖7 C所示，刀片2 1的大負荷使驅動馬達中的電流 根據負荷較大，而小負荷使電流較小且趨近最低的驅動 値。因此，當刀片在燒結表面上經過時，刀片在常態下傾 向於接收由於表面的粗糙度所造成的阻力。但是，如果刀 -17- 1232786 (14) 片在表面上方經過，則刀片不接收任何負荷。因此，如圖 7 C所示，電流値在恆常移動期間被監視，並且根據如此 獲得的電流値與一預定値之間的比較，必須決定載台20 是否應被降低。 另外，如圖8所示，當要被燒結的層從較高密度層改 變爲較低密度層時，載台20的下沈量應從一預定値t (50μιη )改變成爲一較小的値t s (例如2 0 μιη )，並且一 粉末材料層可在低密度燒結條件下被形成及燒結而形成較 低密度層1 1 L。 另外，如圖9所示，當要被燒結的層從較高密度層改 變爲較低密度層時，比預定値稍大的較高密度層1 1 Η被 形成且被削除至預定値，然後一粉末材料層可在低密度燒 結條件F被形成及燒結而形成較低密度層1 1 L。 在每一例子中，雖然用於高，中間，及低密度燒結的 條件被顯不成爲典型的例子，但是一燒結層可包含較高密 度部份及較低密度部份。如圖1 〇所示，包含一較低密度 部份的一燒結層形成在包含一較高密度部份的另一燒結層 上。在圖1 0中，Μ標示中間密度部份。 在本發明中，可使用含鐵粉末混合物成爲無機粉末材 料，例如50重量％ (百分比）的含鐵粉末與選擇自由 鎳’鎳合金，銅，及銅合金所構成的群類的非鐵粉末的混 合物。 典型的混合物包含70至90重量％的Cr-M〇_Fe合 金，5至30重量％的P-Cii或Mn-Cu合金，及〇至1〇重 -18- 1232786 (15) 量°/。的鎳。平均粉末尺寸是在0.1與200 μιη之間，以1至 ΙΟΟμιη較佳，而以5至5〇μτη更佳。本發明可應用於有機 粉末材料。 雖然已經參考圖式以舉例說明的方式完全地敘述本發 明’但是此處應注意對於熟習此項技術者而言，各種不同 的改變及修正很明顯。因此，除非此種改變及修正脫離本 發明的精神及範圍，否則其應被解讀爲包含在本發明內。 【圖式簡單說明】 圖1爲根據本發明的第一實施例的三維物體的製造方 法的說明圖。 圖2爲根據本發明的第二實施例的三維物體的製造方 法的說明圖。 圖3爲根據本發明的第三實施例的三維物體的製造方 法的說明圖。 圖4爲根據本發明的第四實施例的三維物體的製造方 法的說明圖。 圖5爲根據本發明的第五實施例的三維物體的製造方 法的說明圖。 圖6 Α及6 Β爲顯示用於較低密度層的粉末材料層的 測量步驟及設定步驟的說明圖。 圖7A及7B爲顯示用於較高密度層的粉末材料層的 測量步驟及設定步驟的說明圖，而圖7C顯示用來使粉末 材料層均平的刀片的驅動負荷改變。 - 19- 1232786 (16) 圖8爲根據本發明的第五實施例的三維物體的製造方 法的說明圖。 圖9爲根據本發明的第六實施例的三維物體的製造方 法的說明圖。 圖1 〇爲由本發明的方法製造所得的燒結製品的剖面 圖。 圖1 1爲用來顯示根據本發明的三維燒結製品的製造 步驟的示意圖。 圖1 2爲顯示如何根據本發明製造三維燒結製品的資 料流程。 圖1 3爲用來執行本發明的方法的設備的立體圖。 圖14爲具有較高密度區域的模型的示意圖。 圖1 5 A及1 5 B爲由本發明製造之後照原樣的多個燒 結層以及在其表面區域已經被移除之後的多個燒結層的直 立剖面圖。 圖1 6至1 8爲顯示傳統方法中發生的問題的說明圖。 【符號說明】 1〇 粉末材料層 11 較高密度層 1 1 Η較高密度層 11L較低密度層 2〇 載台 1 預定値，預定厚度 -20- 1232786 (17) to 厚度 ό 差異 δ a載台差異 2 粉末層形成單元 3 燒結層形成單元 4 表面層移除單元 5 驅動單元 10 粉末材料層，粉末層 11 燒結層 1 1 Η較高密度燒結層，較高密度層 1 1 Η ’ 附加較高密度層，附加層 1 1 L較低密度層 1 1 Μ中間層，中間密度層 1 IMa 中間密度層 11Mb 中間密度層 1 lMc 中間密度層 12 高密度區域 16 低密度表面層 2 0 載台’燒結台 2 1 校平刀片，擠壓刀片 22 底座 2 5 模製槽 30 雷射射束產生器 3 1 偏轉板 -21 - 1232786 (18) 40 XY驅動單元 4 1 完工機，銑刀頭 F 驅動負荷 L 光束（雷射射束） Μ 想要的形狀 Μ 中間密度部份 Ν 內部區域 Ρ 探針 5 表面區域 t 預定値 t + 5 a 厚度 △ 11想要的厚度，較佳厚度 δ a差異 -22-1232786 (1) 发明 Description of the invention [Technical field to which the invention belongs] The present invention relates to a method for manufacturing a three-dimensional sintered product, in which a target object is obtained by sintering and hardening a powder material layer with a light beam, and the present invention is particularly related to A method of preparing a metal mold by combining a plurality of laminates made of a metal powder layer sintered by a laser beam. [Prior Art] Japanese Patent No. 26203 5 3 discloses a method for manufacturing a three-dimensional object called a photoshaping. According to this patent, a light beam L is first irradiated on a predetermined portion of a powder material layer composed of a powder material which may be an organic material or an inorganic material to form a sintered layer. Then, the sintered layer thus obtained is covered with a new powder material layer, and the light beam L is irradiated on a predetermined portion of the new layer to form a new sintered layer combined with the underlying layer. These steps are repeatedly performed to form a sintered product or a three-dimensional object 'in which a plurality of sintered layers are firmly stacked one above the other. According to this method, the irradiation of the light beam L is performed according to the sectional form data of each layer, and the data is obtained by cutting the model of the design data (CAD data) of the three-dimensional object into a desired thickness . Therefore, compared with the conventional cutting and machining methods, the above-mentioned method can be used to quickly manufacture an arbitrary-shaped three-dimensional object and obtain an object of any shape having a desired shape without a CAM device. But according to this method, considering the problems such as warping and cracking due to the molding time and internal -5- 1232786 (2) stress, this method should be performed by sintering the necessary part to a higher density and Sintering the remaining portions to a lower density is performed instead of sintering all the portions to the same density. For example, in the case of injection molding metal molds, the surface portion for the reproduction of the object and the pipe portion for the cooling water should be formed at a higher density, and the remaining portion should be formed at a lower density. Density formation. The higher density sintered layer has a very smooth finished surface due to almost complete melting and solidification, thus maintaining the watertightness of the cooling water line. However, the powder material layer having a density of 50% to 60% will be sintered into a higher density layer having a density of almost 100%, so that as shown in FIG. 16, when the powder material layer 10 having a thickness of tG will pass through When sintered into a higher density layer 1 1 Η by optical irradiation, the surface level of the higher density layer is reduced by a difference from the original surface level of the powder material layer 5. In addition, when the thickness of the powder material layer is determined by the sinking amount of the stage 20, the thickness of the powder material layer is set to be larger than a predetermined 値 t, and in addition, when the powder material layer 10 will be When sintered under higher density sintering conditions, the surface of the resulting higher density layer will reduce the stage difference (the difference < 5a is greater than the difference δ). In addition, another powder material layer 10 is formed on the higher density layer 11 and is sintered under conditions for lower density to form a lower density layer 11 L. As shown in FIG. 18, the powder material layer 10 becomes thicker in this case with the above-mentioned difference (5a. In this method, because the beam conditions for lower density are based on the powder material layer 10 The predetermined thickness t is determined, so the -6-1232786 with the predetermined conditions (3) the beam cannot make the powder material thicker than the fully sintered predetermined thickness t by a certain difference (5 a 'M I without giving the resulting lower density layer sufficient The adhesive power makes the lower-density layer easy to peel off from the higher-density layer. SUMMARY OF THE INVENTION The present invention has been developed to overcome the disadvantages described above. Therefore, an object of the present invention is to provide an innovative and feasible method. A method of manufacturing a three-dimensional fire-bonded product, which provides good adhesion between a higher density layer and a lower density layer. Another object of the present invention is to provide a method of the type described above, which can be prepared with A three-dimensional sintered product of a lower-density layer that is completely sintered under predetermined conditions of the density layer. When the above and other objects are achieved, from the first aspect of the present invention, a method for preparing a three-dimensional sintered product is provided. , Which includes the steps of (a) sintering a predetermined portion of a first powder material layer by irradiation of a first light beam to form a first layer having a higher density, (b) in the first Forming a second powder material layer on the layer, (c) sintering a predetermined portion of the second powder material layer by irradiation of a second light beam to form a second layer having a lower density and Two lower-density layers are combined with the first higher-density layer, and (d) steps (a) to (c) are repeated to form a three-dimensional sintered block comprising a plurality of the first and second layers, which has a low density The second sintered layer is formed by an additional sintered layer having an intermediate density of 1232786 (4) degrees between the high density of the first sintered layer and the low density of the second sintered layer. On the first sintered layer. According to the first feature of the present invention, the second sintered layer having a lower density is not formed directly on the first sintered layer with a higher density via an additional layer having an intermediate density, so that the The adhesion between the high density layer and the lower density layer can be Due to the sequential change from higher density to lower density and without forming any insufficient lower density sintered layer without weakening. In this method, the additional sintered layer with intermediate density may include multiple layers, where The density of each layer decreases in proportion to the distance from the higher density layer. A smooth change in density in the intermediate density layer can form a smooth change in characteristics from the higher density layer to the lower density layer. In this case, it is appropriate The sintering conditions should be determined according to the thickness of the powder material layer to be sintered, so that the intermediate density layer can be formed in suitable sintering conditions. From the second aspect of the present invention, a method for preparing a three-dimensional sintered product is provided, 'The three-dimensional sintering. The article includes a higher density layer and a lower density layer sintered by irradiating a predetermined portion of the powder material layer with a beam, wherein a powder for the lower density layer on at least the uppermost higher density layer The material layer is formed to have a thickness smaller than a usual predetermined thickness and withstand a sintering process according to the sintering conditions of the lower density layer. According to a second feature of the invention, the powder material for the lower density layer is formed as a layer having a suitable thickness for sintering. Therefore, if the higher density layer is formed smaller than a predetermined volume, the next powder material layer is always set to have a suitable thickness for predetermined sintering conditions, so that the resulting lower density layer has good adhesion. -8-1232786 (5) From the third aspect of the present invention, there is provided a method for producing a three-dimensional sintered product, the three-dimensional sintered product comprising a higher density sintered by irradiating a predetermined portion of the powder material layer with a light beam Layers and lower density layers, wherein a powder material layer for the higher density layer on at least the uppermost higher density layer is formed to have a thickness smaller than a usual predetermined thickness and withstand the sintering conditions according to the lower density layer Sintering process. According to a third feature of the present invention, an additional higher-density layer is formed to adjust the formation position for the lower-density layer, even if the higher-density layer is formed to be smaller than a predetermined volume, so that the next powder for the low-density layer is formed. The material layer is controlled to have a suitable thickness for sintering, thereby forming a lower density layer with good adhesion. In this method, the thickness of the powder material layer can be determined by the amount of sinking of the stage on which the obtained layer is positioned, and the next powder material layer is formed on the obtained layer. An additional higher density layer can be formed without any amount of settling on the stage. In this case, the operation time for sinking the stage can be reduced. When a lower density layer is formed on a higher density layer, the thickness of the powder material layer and the sintering conditions can be measured by measuring the height of the product already formed and / or the driving load of the blade used to level the powder material layer. was decided. According to this method, an excessive thickness of the powder material for the lower density layer can be reliably avoided. According to the fourth aspect of the present invention, when the lower density layer is formed on the higher density layer, the higher density layer is formed to have a thickness larger than a predetermined thickness, and then is cut to a predetermined thickness. Therefore, the thickness of the powder material for the lower density layer can be set to a predetermined level on the surface of the higher density layer positioned at a predetermined height of -9-1232786 (6) degrees, so that the powder material layer can be A light beam with suitable conditions is sintered, which can avoid the formation of a lower density layer with poor adhesion. As described above, according to the present invention, the thickness of the powder material for the lower density layer can be controlled by the presence of the intermediate density layer, the thickness of the powder material for the lower density layer, and the formation of an additional higher density layer. And being controlled to be not more than a predetermined volume, the formation of a lower density layer with poor adhesion and the separation between the higher density layer and the lower density layer can be avoided. The above and other objects and features of the present invention will be more apparent from the following description of the preferred embodiments of the present invention with reference to the drawings, in which the same portions are designated by the same reference numerals. [Embodiment] This case is based on applications No. 2002-2 8 77 68 and 2003-2 8 1 25 9 filed in Japan on September 30, 2002 and July 28, 2003, the contents of which are borrowed The entire reference is explicitly incorporated herein. In the method of the present invention, three-dimensional sintered products can be manufactured using different kinds of equipment. Referring now to the drawings, in an apparatus for carrying out the embodiment shown in the figure, a stage 20 which is moved up and down is positioned in a molding groove 25. The powder material is supplied onto the stage 20 to form a powder material layer 10 having a predetermined thickness by a squeezing blade. Then, a predetermined portion of the powder material layer is irradiated with a light beam (laser beam) L operated by the scanning optical system to form a sintered layer 11. The beam system for irradiating the light beam is provided with a control mechanism for changing the scanning pitch and the scanning rate -10- 1232786 (7). Higher density sintered layers can be formed by high sintering conditions with smaller scan pitches and slower scan rates. On the other hand, a lower density sintered layer can be formed by a low sintering condition having a larger scanning pitch and a faster scanning rate. Of course, the output of the light beam can be changed according to a predetermined control schedule. In detail, Fig. 13 shows an apparatus for manufacturing a three-dimensional object according to the first embodiment of the present invention. The apparatus shown in the figure includes a powder layer forming unit 2 for forming a powder layer 10, a sintering layer forming unit 3 'for forming a sintered layer 11, and a surface layer removing unit 4 for removing a low-density surface layer. The powder layer forming unit 2 forms a powder layer 10 having a desired thickness Δί1 by supplying an organic or inorganic powder material to a sintering table 20 that moves upright in a space surrounded by a cylinder, and by The leveling blade 21 is used to level the powder material. The sintering table 20 is driven by the driving unit 5 to move up and down. The sintered layer forming unit 3 forms a sintered layer 11 by irradiating a laser beam emitted from a laser beam generator 30 with a powder layer 10 through a scanning optical system including a deflector 31 and the like. A laser oscillator is preferably used as the laser beam generator 30. The surface layer removing unit 4 includes a χγ drive unit 40 mounted on its base, and a finishing machine 41 mounted on the XY drive unit 40. The XY drive unit 40 is preferably driven by a linear motor at high speed. A galvanized mirror is preferably used as the deflection plate 31. A cutting machine such as an end mill or drilling machine, a laser beam machine, or a * blasting machine for performing plastic working with respect to an object by blowing sintered powder on the object is preferably Used by -11-1232786 (8) to become finisher 41. A polar coordinate driving unit may be used instead of the XY driving unit 40. Figure Π shows how to use the equipment described above to make a three-dimensional object. As shown in the figure, the organic or inorganic powder material is first supplied to the base 22 mounted on the sintering table 20, and it is adopted as a distance adjuster for adjusting the distance between the sintering layer forming unit 3 and the sintering layer. . Then, the powder material supplied to the base 22 is leveled by the leveling blade 21 to form a first powder layer 10, and a light beam (laser beam) L is irradiated on a desired portion of the first powder layer 10. To sinter it, thereby forming a sintered layer 11 in combination with the base 22. Then, the sintering table 20 is lowered by a predetermined length, and a second powder layer 10 is formed by supplying the powder material again and leveling it by using a leveling blade 21. The light beam L is again irradiated on a desired portion of the second powder layer 10 to sinter it, thereby forming another sintered layer 11 which is combined with the lower sintered layer 11. The process of forming a new powder layer 10 after the sintering table 20 is lowered and the process of irradiating a light beam L on a desired portion of the new powder layer 10 to form a new sintered layer 11 are repeatedly performed. Thus a three-dimensional object is manufactured. The approximately spherical iron powder particles having an average diameter of about 20 μχη (micrometers) are preferably used as a powder material, and a co2 laser is preferably used as a light beam. The preferred thickness Δ1 of each powder layer 10 is approximately 0.05 mm (mm). FIG. 12 shows an example of a data flow according to the present invention. This data flow enables the desired three-dimensional CAD model to have two kinds of data, that is, -12- 1232786 (9) data showing the laser irradiation path and data indicating the cutting path. These paths are prepared from pre-designed 3D CAD data to indicate the desired shape. The laser irradiation path is roughly the same as in the conventional forming method, where the target shape is obtained by slicing the STL data generated from the 3D CAD model at equal pitches (0.05 mm in this embodiment). Defined by the contour data of each sector. The profile data is appended with laser irradiation conditions (scan rate, spot diameter, power, and the like) to generate new data, and the new data is sent to the completion process. The cutting path is a path obtained in consideration of the diameter, kind, feed rate, rotation rate, etc. of a finished tool to be used in the three-dimensional CAM. Information indicating this route was also sent to the completion process. The data indicating the laser irradiation path is used in the laser sintering process, and the data indicating the cutting path is used in the high-speed cutting process. These two processes are repeatedly performed to complete the target shape. The irradiation of the light beam is implemented so that at least the surface area of the three-dimensional object is preferably sintered to have a high density (for example, less than 5% porosity). The reason is that even if the surface layer is removed by the surface layer removing unit 4, if the surface area has a low density, the surface exposed after the surface removal process is still porous. Therefore, as shown in Fig. 14, the model data is divided into a model data for the surface area S and a model data for the inner area N, and the inner area N becomes porous and the surface becomes large when most of the powder material is melted by the light beam. The region S is irradiated under conditions with a high density. In Fig. 15A, reference numeral 12 indicates a high-density area, and reference -13-1232786 (10) reference numeral 16 indicates a low-density surface layer produced by adhesion of a powder material as discussed above. The inner portion located inside the high-density region 12 has a density lower than that of the high-density region 12 but higher than the density of the low-density surface layer 16. During the formation of the plurality of sintered layers 11, when the total thickness thereof reaches a specific thickness determined from a tool length such as a milling head 41, the surface layer removing unit 4 is activated to cut a shape that has been formed at that time. The surface of a three-dimensional object. For example, a tool (ball end mill) with a milling head 41 having a diameter of 1 mm and an effective blade length of 3 mm can achieve a depth of 3 mm. Therefore, if the thickness Δ t1 of the powder layer 10 is 0.05 mm, the surface layer removing unit 4 is activated when sixty sintered layers 11 have been formed. As shown in FIG. 15A, such a surface layer removing unit 4 can remove a low-density surface layer 16 produced by adhesion of a powder to a surface of a shaped object, and can simultaneously cut out a portion of a high-density region 2 Therefore, the high-density area 12 is exposed on the entire surface of the shaped object, as shown in FIG. 5b. For this purpose, the shape of the sintered layer 11 is formed to a size slightly larger than the size of the desired shape M. For example, when the light beam L is irradiated along a desired contour line under the conditions given below, the horizontal size (width) of each sintered layer 11 becomes larger than the size of the desired shape] VI by about 0.3 mm. Laser power: 200W (watt) Laser spot diameter: 0.6 mm Scan rate: 50mm / s (mm / s) -14-1232786 (11) Excess thickness in the upright direction may be equal to or different from the excess thickness in the horizontal direction . The upright size of the shape of the sintered layer 11 is obtained by modifying the original data indicating the upright size of the desired shape M. In the case where the cutting is performed using a round-end groove milling cutter having a diameter of 1 mm, the cutting depth, the feed rate, and the rotation rate of the tool are set to 〇 · 1 to 0 · 5 mm, 5 to 5, respectively. 0 m / mi η (meters / minute), and 20,000 to 1 000 000 rpm is preferred. An example is shown in FIG. 1. On the stage 20, two high-density sintered layers 1 are formed by high-density sintering conditions such as a laser power of 200W, a scanning pitch of 0.2mm, and a scanning rate of 50mm / Sec. 1 Η, 1 1 Η. Then, the intermediate layer 11 M is formed by a light beam L under a medium density sintering condition such as a laser power of 200 W, a scanning pitch of 0.3 mm, and a scanning rate of 100 mm / sec. Then, the lower density layer 11L is formed by a light beam under a low density sintering condition such as a laser power of 200 W, a scanning pitch of 0.5 mm, and a scanning rate of 300 mm / sec. In this example, even if the powder material layer 10 has a thickness larger than that used for the lower density sintering conditions, the intermediate density sintering conditions are sufficient for the powder material layer having the larger thickness to be completely sintered, so that the intermediate can be avoided Separation between the density layer 11 M and the higher density layer 11 M. As shown in FIG. 2, the intermediate layer may include a plurality of layers 11Ma, 11Mb, and 1 1Me, and the sintering conditions thereof are reduced according to the distance to the lower density layer. For example, the intermediate density layer 1 1 Ma, which is closer to the higher density layer 1 1 Η, will be set to -15-1232786 (12) at, for example, a laser power of 200 W, a scan of 0.3 mm | a scan rate of 1 OO mm / sec. Sintering conditions, and the intermediate density will be set at sintering conditions such as 200W laser power, 0.35mm pitch, and a scan rate of 150 mm / sec, while the denser layer 1 1 L intermediate density layer 1 1 M c is set at, for example, laser power, a scanning pitch of 0.4 mm, and a sintering condition of 200 mm / sec. Instead of this condition, under the same conditions as the power and scan pitch of the lower density sintered bar, the scan rate can be controlled the closer the layer is to the lower density layer, the higher. As shown in Figure 3, after the higher density layer is formed, the difference 5 a between the higher density layers of the powder can be used to measure the height; and the thickness of the next powder material layer (t + 5a) is also used. The sintering conditions for the 1M of the intermediate density layer can be determined by measurement. The appropriate conditions for the intermediate density layer can be determined based on experimental data. In addition, as shown in FIG. 4, when the lower density layer 1 1 L is formed on the degree layer 11 ′, the sinking amount (including zero) of the stage 20 may be smaller than a predetermined 値 t. Appropriate thickness for low density layer 1 in low conditions. In addition, 'as shown in Fig. 5, in order to offset the powder material layer] the difference between the density layer 1 1 Η 5 a, the sintered higher density stage does not lower or lower than the predetermined 値 t, and the powder material To fill the space. In this case, an additional higher-density layer is formed to offset the difference. Then a lower-density layer can be in a lower-density range, and: the 11Mb scan section is close to the laser system of the lower 200W scan rate device It will be measured with the material layer and deep needle P measurement, and the result will be determined in advance. The density will be set at a higher density and sintered in advance. 〇 After the higher, the carrier material is supplied 1 1 Η 'formed sintering conditions-16-1232786 ( 13) Under formation. In the case of large differences, multiple additional higher density layers may be formed according to the procedure described above. The thickness of the additional higher density layer may gradually become thinner, and the last lower density layer may be formed. In Fig. 5, 2 1 denotes a squeeze blade. In addition, as shown in FIG. 6A, when the difference between the powder layer 10 and the higher-density layer 11H is measured, the next step may be selected from the following steps according to the measurement result, that is, step (a)-lower density The layer 11L is formed after the formation of the additional higher-density layer 11 H ′, or (b) —the lower-density layer 11L is formed directly on the higher-density layer 11H without the additional layer 11H5. In the case of a large difference a, as shown in FIG. 6B, a powder material layer is formed without any sinking on the stage 20, and the powder material layer is sintered into a higher density layer 1 1 Η 'to make the difference Smaller. In the case of a small difference? A, the stage 20 is lowered, a powder material is supplied, and a lower density layer 11 L is formed. As shown in Fig. 7, the difference (5a can be measured by the driving load F of the blade 21 used to level the powder material. In the case of a smaller load F equal to the large difference shown in Fig. 7A In the case, the next powder material layer is formed under the stage 20 without any sinking amount. In the case of a large load F equal to the small difference shown in FIG. 7B, the next powder material layer has It is formed under a certain amount of sinking. As shown in FIG. 7C, the large load of the blade 21 causes the current in the drive motor to be larger according to the load, while the small load makes the current smaller and approaches the lowest drive 的. Therefore, when When a blade passes over a sintered surface, the blade normally tends to receive resistance due to the surface roughness. However, if the blade -17-1232786 (14) passes over the surface, the blade does not receive any load. Therefore As shown in FIG. 7C, the current 値 is monitored during the constant movement, and based on the comparison between the current 如此 thus obtained and a predetermined 値, it must be determined whether the stage 20 should be lowered. In addition, as shown in FIG. 8 It is shown that when the layer to be sintered is changed from a higher density layer When changing to a lower density layer, the sinking amount of the stage 20 should be changed from a predetermined 値 t (50 μιη) to a smaller 値 ts (e.g., 20 μιη), and a powder material layer can be used under low density sintering conditions It is formed and sintered to form a lower density layer 1 1 L. In addition, as shown in FIG. 9, when the layer to be sintered is changed from a higher density layer to a lower density layer, a higher density is slightly larger than a predetermined value. Layer 1 1 Η is formed and cut to a predetermined 値, and then a powder material layer can be formed and sintered under low density sintering condition F to form a lower density layer 1 1 L. In each example, although used for high, Intermediate and low-density sintering conditions are not a typical example, but a sintered layer may include higher-density portions and lower-density portions. As shown in FIG. 10, a The sintered layer is formed on another sintered layer containing a higher density portion. In FIG. 10, M indicates a middle density portion. In the present invention, an iron-containing powder mixture may be used as the inorganic powder material, for example, 50 weight % (Percent) of iron-containing powder with selection from A mixture of non-ferrous powders of nickel, nickel alloy, copper, and copper alloys. A typical mixture contains 70 to 90% by weight of a Cr-M0_Fe alloy, and 5 to 30% by weight of P-Cii or Mn-Cu alloy, and 0 to 10 weight -18-1232786 (15) the amount of nickel. The average powder size is between 0.1 and 200 μm, preferably 1 to 100 μm, and 5 to 50. μτη is better. The invention can be applied to organic powder materials. Although the invention has been fully described by way of example with reference to the drawings, it should be noted here that for those skilled in the art, various changes and modifications are very Obviously, unless such changes and modifications depart from the spirit and scope of the present invention, they should be construed as being included in the present invention. [Brief Description of the Drawings] Fig. 1 is an explanatory diagram of a method for manufacturing a three-dimensional object according to a first embodiment of the present invention. Fig. 2 is an explanatory diagram of a method of manufacturing a three-dimensional object according to a second embodiment of the present invention. Fig. 3 is an explanatory diagram of a method of manufacturing a three-dimensional object according to a third embodiment of the present invention. Fig. 4 is an explanatory diagram of a method of manufacturing a three-dimensional object according to a fourth embodiment of the present invention. Fig. 5 is an explanatory diagram of a method of manufacturing a three-dimensional object according to a fifth embodiment of the present invention. 6A and 6B are explanatory diagrams showing a measurement procedure and a setting procedure of a powder material layer for a lower density layer. Figs. 7A and 7B are explanatory diagrams showing a measurement procedure and a setting procedure of a powder material layer for a higher density layer, and Fig. 7C shows a driving load change of a blade for leveling a powder material layer. -19- 1232786 (16) Fig. 8 is an explanatory diagram of a method for manufacturing a three-dimensional object according to a fifth embodiment of the present invention. Fig. 9 is an explanatory diagram of a method of manufacturing a three-dimensional object according to a sixth embodiment of the present invention. Fig. 10 is a cross-sectional view of a sintered product produced by the method of the present invention. Fig. 11 is a schematic view showing the manufacturing steps of a three-dimensional sintered product according to the present invention. Fig. 12 is a data flow showing how to manufacture a three-dimensional sintered product according to the present invention. FIG. 13 is a perspective view of a device for performing the method of the present invention. FIG. 14 is a schematic diagram of a model having a higher density region. Figures 15A and 15B are vertical cross-sectional views of a plurality of sintered layers as they are after being manufactured by the present invention and a plurality of sintered layers after their surface regions have been removed. 16 to 18 are explanatory diagrams showing problems occurring in the conventional method. [Symbol description] 10 Powder material layer 11 Higher density layer 1 1 Η Higher density layer 11L Lower density layer 20 Stage 1 Predetermined, predetermined thickness -20-1232786 (17) to thickness δ difference a load Difference 2 Powder layer forming unit 3 Sintered layer forming unit 4 Surface layer removing unit 5 Drive unit 10 Powder material layer, powder layer 11 Sintered layer 1 1 ΗHigh density sintered layer, High density layer 1 1 Η High density layer, additional layer 1 1 L lower density layer 1 1 M intermediate layer, intermediate density layer 1 IMa intermediate density layer 11Mb intermediate density layer 1 lMc intermediate density layer 12 high density area 16 low density surface layer 2 0 stage Sintering table 2 1 Leveling blade, extrusion blade 22 Base 2 5 Moulding slot 30 Laser beam generator 3 1 Deflection plate-21-1232786 (18) 40 XY drive unit 4 1 Finishing machine, milling head F drive Load L beam (laser beam) Μ Desired shape Μ Intermediate density portion Ν Inner area P Probe 5 Surface area t Scheduled 値 t + 5 a Thickness △ 11 Desired thickness, preferably thickness δ a Difference- twenty two-