200821537 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種量測高爐内壁之外形之方法，詳言 之，係關於一種評估高爐内喷漿效果之方法及量測高爐爐 壁殘厚之方法。 【先前技術】 二維雷射掃描儀由於取樣快速（25000點/秒）、準確（約 20mm)及量測範圍廣（大於1〇〇m)等特性，已逐漸被應用在 許多領域，如土木、建築及古蹟維護等領域，如文獻[曾 義生史天元，二維雷射掃描儀一新一代量測利器"，科 车毛展，2003年5月，365期]所揭示。在鋼鐵製程則可應 用在轉爐的爐襯厚度（如美國專利第6,922,251號所揭示）， 以及料面外形上（如文獻[E· MeUer and j Heiimich，，,Full200821537 IX. Description of the Invention: [Technical Field] The present invention relates to a method for measuring the shape of the inner wall of a blast furnace, and more particularly to a method for evaluating the effect of spraying in a blast furnace and measuring the residual thickness of the blast furnace wall The method. [Prior Art] Two-dimensional laser scanners have been gradually applied in many fields, such as civil engineering, due to their fast sampling (25,000 points/second), accuracy (about 20mm), and wide measurement range (greater than 1〇〇m). In the fields of construction and historic site maintenance, such as the literature [Zeng Yisheng Shi Tianyuan, 2D Laser Scanner, A New Generation of Measuring Instruments ", Science and Technology Maozhan, May 2003, 365]. In the steel process, it can be applied to the thickness of the lining of the converter (as disclosed in U.S. Patent No. 6,922,251), as well as the shape of the material (such as the literature [E· MeUer and j Heiimich,,, Full
Automation of Stacker and Reclaimers^, Bulk Solids Handling，Vol 21，No, 5, 2001]所揭示）。 參考圖1，顯示習知高爐之示意圖。該高爐丨係為煉鐵技 術中重要之反應器。該南爐1包括爐頂1 1、爐喉1 2、爐身 13、 爐腰14、爐腹15及爐床16。該爐頂11係為圓錐狀，該 爐喉12係為圓柱狀，且該爐頂丨1及該爐喉12之材質係為 鋼。6亥爐頂11具有複數個人孔1，該等人孔111 係為可打開以暴露出該雨爐1内部。該爐身、該爐腰 14、 4爐腹1 5及讜爐床1 6之爐壁之材質係為耐火材，用以 容納液態鐵17。該液態鐵17具有一料面171。 參考圖2 ’顯示習知高爐在長時間運轉後爐身爐壁被侵 115269.doc 200821537 敍之示意圖，其中Tl代表該爐身13爐壁之原始厚度，12代 表該爐身13爐壁被侵蝕後之殘餘厚度。由於該高爐1長年 累月在高溫高壓的惡劣環境下運轉，爐壁的耐火材會逐漸 被侵蝕，其主要原因有：該液態鐵17料層下降所造成之機 械性磨耗、化學侵蝕及熱侵蝕等，如文獻[賴鳳成，"中鋼 高爐内襯碑使用探討"，技術與訓練，21卷，二期，卯 57-66]所揭不。因此，該高爐丨經過一段時間運轉後必須停 爐以進行該爐身13之喷漿作業，以增加該高爐丨之壽命。 參考圖3，顯示習知高爐在進行噴漿作業示意圖。該喷 漿作業係將-機具2懸吊至該高爐1内，以液體狀之耐火材 21對該爐身13爐壁進行喷附以形成一喷漿厚度τ3。由於受 限於環境以及設備等因f，一直無法對爐壁上之該喷衆厚 度丁3進行量測與評估，而無法評估噴漿作業之品質。此 外，由於該機具2所喷出之耐火材21係為液體狀，所以在 喷漿過程中會經由爐壁回彈至底部之料面m而形成一回 彈量厚度了4’經過—段時間後位於該料面i7i上之耐火材 會凝固成相當堅硬之外殼’而阻隔該高爐1在開爐後底部 南溫氣體向上流動之路徑，如此對開爐程序影響报大，甚 至造成危險。然而’同樣地，受限於環境以及設備等因 素，一直無法對該料面171上之回彈量厚度丁4進行量測與 評估。 高爐内喷 因此’有必要提供一種創 別研且具進步性的評估 漿政杲之方法，以解決上述問題。 f發明内容】 115269.doc 200821537 方法，在於，供-種評估高爐内噴製效果之 堂 u ^驟·（a)量測取得一第一戈一 弟一次三维點群係 一 火二維點群，該 、 $於該面爐内壁之外开）· π、 内壁進行噴漿作章 /, (b)對該高爐 - a — ”，C里測取得一第二次三維點群 雄 —_人二維點群传 再點群，該第 斜兮止對於該高爐内壁喷漿後之外來.R 對该步驟（a)之塗一 * 一 文孓夕卜形，及（d)比 -人二維點群及該步驟（ 點群，以得到„ 叩）之弟二次三維Automation of Stacker and Reclaimers^, Bulk Solids Handling, Vol 21, No, 5, 2001]. Referring to Figure 1, a schematic view of a conventional blast furnace is shown. This blast furnace is an important reactor in ironmaking technology. The south furnace 1 includes a furnace top 1 1 , a throat 1 , a shaft 13 , a furnace waist 14 , a belly 15 and a hearth 16 . The top 11 is conical, the throat 12 is cylindrical, and the top sill 1 and the throat 12 are made of steel. The 6-shaped furnace top 11 has a plurality of individual holes 1 which are openable to expose the inside of the rain oven 1. The material of the furnace body, the waist of the furnace 14, the belly of the furnace, and the wall of the crucible bed 16 are made of a refractory material for accommodating the liquid iron 17. The liquid iron 17 has a dough 171. Refer to Figure 2' to show the schematic diagram of the furnace wall intrusion after the long-term operation of the furnace. 115269.doc 200821537, where Tl represents the original thickness of the furnace wall 13 and 12 represents the erosion of the furnace wall 13 The residual thickness afterwards. Since the blast furnace 1 is operated in a harsh environment of high temperature and high pressure for many years, the refractory material of the furnace wall is gradually eroded. The main reasons are: mechanical abrasion, chemical corrosion and thermal erosion caused by the falling of the liquid iron 17 layer. For example, the literature [Lai Fengcheng, " Sinosteel blast furnace lining monument use discussion ", technology and training, 21 volumes, two issues, 卯 57-66] is not revealed. Therefore, the blast furnace must be shut down after a period of operation to perform the shotcreting operation of the shaft 13 to increase the life of the blast furnace. Referring to Figure 3, a schematic view of a conventional blast furnace in which a shotcreting operation is performed is shown. The blasting operation suspends the implement 2 into the blast furnace 1, and sprays the furnace wall 13 with a liquid refractory material 21 to form a spray thickness τ3. Due to the limited environment and equipment, it has not been possible to measure and evaluate the thickness of the spray on the wall, and it is impossible to evaluate the quality of the shot. In addition, since the refractory material 21 sprayed by the implement 2 is liquid, it will rebound to the bottom surface m through the furnace wall during the shotcreting process to form a rebound amount of thickness 4'. The refractory material located on the material surface i7i will solidify into a relatively hard outer shell' to block the upward flow of the southerly temperature gas at the bottom of the blast furnace 1 after the furnace is opened, thus causing a large impact on the furnace opening procedure and even causing danger. However, similarly, it is impossible to measure and evaluate the rebound thickness 4 on the material surface 171 due to factors such as the environment and equipment. In the blast furnace, it is necessary to provide a method for the evaluation of the slurry policy to solve the above problems. f invention content] 115269.doc 200821537 method, is to provide a kind of evaluation of the effect of spraying in the blast furnace u ^ (a) measurement to obtain a first Ge Yidi once three-dimensional point group system fire two-dimensional point group , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , The point group is transmitted to the group, and the first slanting point is applied to the inner wall of the blast furnace. The R is coated with the coating of the step (a), and (d) the ratio of the person to the two-dimensional point. Group and the step (point group to get „ 叩) brother second three-dimensional
/ 厚薄不均之情形予度。精此…檢驗嘴聚品質是否有 法本!Γ另—目的在於提供一種量測高爐爐壁殘厚之方 法’包括以下步驟：⑷量測取得一第一 ^之方 -次三維點群係相對於該高爐内壁之目前二:：二第 :械尺寸模型’該機械尺寸模型係相對於該高爐= 對該步驟⑷之第一次三維點群《步驟 _ 以仵到该咼爐之爐壁殘厚。藉此，可 评估該高爐之擔彳七|人 坻代可〒。另外，也可以依照該爐壁殘厚之 =佈情形標示出侵姓量較嚴重部分之位置，以規劃喷聚之 序0 【實施方式】 參考圖4 ’顯示本發明評估高爐内錢效果之方法之較 佳實^例之流程圖。本實施例所f測及評估之高⑴係為 圖1之高爐1。該方法包括以下步驟。步驟S4〇1係架設一個 三維雷射掃描儀於該高爐1内。在本實施例中，是以一型 號為RIEGL LMS-Z2H)k三維雷射掃描儀為例，其係為以 飛行時間（dme of flight)為原理的雷射測距系統。量測 115269.doc 200821537 時’雷射光點由該三維雷射掃描儀發射至待測物並反射至 該三維雷射掃描儀’由光點在空間中的飛行時間計算出待 測物與該三維雷射掃描儀之㈣距離。該三料射掃描儀 並藉由-旋轉機構掃描光點的方式來達成大面積的量測， 其所產生的量測結果為一具有三維座標的點群咖w cl〇Ud)。該旋轉機構有兩個自由度，分別是水平角度财 轉（〇〜330度）以及垂直角度以5〇〜13〇度）的旋轉。旋轉角度 的解析度最高為0.05度，相對應的量測時間約為數分鐘。 在本實施例中’該三維雷射掃描儀係經由該高爐】之爐 頂U之人孔⑴而架設於該高爐！内位於該人孔⑴附近。 步驟S402係啟動該三維雷射掃描儀，以利用該三維雷射 掃描儀量測取得-第-次三維點群， 相對於該高爐丨内壁之外形，如圖5中曲線51所示维·謂係 步驟S4G3絲出該三維雷射掃描儀，时便該噴聚作業 之機具2(圖3)從該人孔iu進人該高爐i進行喷敷。 步驟S404係對該高爐i内壁進行喷裝作業，如圖3所示。 待喷渡作業完成後再將該機具2(圖3)從該人孔⑴吊出。 步驟S405係再架設該三維雷射掃描儀於該高⑴内。在 本實施例中，該三維雷射掃描儀係經由該步驟s4〇i之同一 個人孔111而架設於該高爐以之同一位置。為了得到準確 的量測結果，使錢前後兩次三維雷射掃描儀的架設位置 與角度不會相差過大’且不會導致資料定位困冑，本實施 例在該步驟8401及8405之架設過裎中利用一電子式水平儀 之辅助，在架設過程中進行傾斜度的調整，使兩次三維雷 115269.doc 200821537 射掃描儀在架設時之角度不會相差過大，以減少誤差。在 本實施例中’該電子式水平儀之型號為TESA clin〇bevel 步驟S406係啟動該三維雷射掃描儀，以利用該三維雷射 掃描儀量測取得一第二次三維點群，該第二次三維點群係 相對於該高爐1内壁喷漿後之外形，如圖5中曲線52所示。 步驟S407係比對該步驟S402之第一次三維點群及該步驟 S406之第二次三維點群，以得到噴漿厚度丁3，如圖6所 示。在本實施例中，係對該第一次三維點群及該第二次三 維點群進行一疊代選取最近點（Iterative 卜加， ICP)演算法。該疊代選取最近點演算法的功能係將二個三 維點群進行定位，使其中 一個三維點群所屬的座標系統經/ The degree of uneven thickness is given. This is to test whether the quality of the mouth gathers has a law! Γ Another - the purpose is to provide a method for measuring the residual thickness of the blast furnace wall 'including the following steps: (4) Measurement to obtain a first ^ square - sub-three-dimensional point group relative The current two:: two: mechanical size model of the inner wall of the blast furnace is relative to the blast furnace = the first three-dimensional point group of the step (4) "step _ to the furnace wall of the furnace thick. In this way, the blast furnace can be evaluated. In addition, according to the residual wall thickness of the furnace wall, the position of the severely infringed part may be marked to plan the order of the spray polymerization. [Embodiment] Referring to FIG. 4', the method for evaluating the money effect in the blast furnace according to the present invention is shown. A flow chart of a preferred embodiment. The height (1) measured and evaluated in this embodiment is the blast furnace 1 of Fig. 1. The method includes the following steps. Step S4〇1 erects a three-dimensional laser scanner in the blast furnace 1. In the present embodiment, a three-dimensional laser scanner of the type RIEGL LMS-Z2H) k is taken as an example, which is a laser ranging system based on the principle of dme of flight. Measurement 115269.doc 200821537 When the 'laser spot is emitted by the three-dimensional laser scanner to the object to be tested and reflected to the three-dimensional laser scanner', the object to be tested is calculated from the time of flight of the spot in space and the three-dimensional (4) Distance of the laser scanner. The three-shot scanner and the scanning point of the rotating mechanism achieve a large-area measurement, and the measurement result is a point group w cl〇Ud) having a three-dimensional coordinate. The rotating mechanism has two degrees of freedom, which are the rotation of the horizontal angle (〇~330 degrees) and the vertical angle of 5〇~13〇). The resolution of the rotation angle is at most 0.05 degrees, and the corresponding measurement time is about several minutes. In the present embodiment, the three-dimensional laser scanner is mounted on the blast furnace via the manhole (1) of the furnace top U of the blast furnace! The inside is located near the manhole (1). Step S402 is to activate the three-dimensional laser scanner to measure the obtained first-order three-dimensional point group by using the three-dimensional laser scanner, and the shape of the inner wall of the blast furnace is compared with the shape of the inner wall of the blast furnace, as shown by the curve 51 in FIG. When the step S4G3 is taken out of the three-dimensional laser scanner, the machine 2 (Fig. 3) of the spraying operation is sprayed from the manhole iu into the blast furnace i. Step S404 is a spraying operation on the inner wall of the blast furnace i, as shown in FIG. The implement 2 (Fig. 3) is lifted from the manhole (1) after the completion of the spray operation. Step S405 is to erect the three-dimensional laser scanner in the high (1). In the present embodiment, the three-dimensional laser scanner is mounted at the same position of the blast furnace via the same individual hole 111 of the step s4〇i. In order to obtain an accurate measurement result, the position and angle of the two-dimensional laser scanners before and after the money are not excessively large, and the data positioning is not difficult, and the embodiment is set up in the steps 8401 and 8405. With the aid of an electronic level, the tilt is adjusted during the erection process, so that the angle of the two-dimensional laser 115269.doc 200821537 is not too large when erecting, so as to reduce the error. In this embodiment, the model of the electronic level is TESA clin〇bevel. Step S406 is to activate the three-dimensional laser scanner to obtain a second three-dimensional point group by using the three-dimensional laser scanner, and the second The sub-three-dimensional point group is shaped after being sprayed with respect to the inner wall of the blast furnace 1, as shown by a curve 52 in FIG. Step S407 compares the first three-dimensional point group of step S402 with the second three-dimensional point group of step S406 to obtain a shot thickness D3, as shown in FIG. In this embodiment, an iterative selection of the nearest point (Iterative Buga, ICP) algorithm is performed on the first three-dimensional point group and the second three-dimensional point group. The function of the iterative selection of the nearest point algorithm is to locate two three-dimensional point groups, so that the coordinate system to which one of the three-dimensional point groups belongs is
過旋轉及平移後，與另-個三維點群所屬的座標系統疊 合。在本實施例中，由於該爐喉12以下的部分因耐火材的 喷附而有明顯的變化，所以不適合選取作為該疊代選取最 近點廣算法之特徵點。該爐喉12以上的部分由於在喷漿前 後均屬於不變的結構，因此該疊代選取最近點演算法係選 取該高爐1之爐喉12以上外形所對應之點群作為特徵點。 該喷聚厚度T3可由疊合後之點群加以計算而得。該喷毁厚 度丁3之量測可以檢驗噴漿品質是否有厚薄不均之情形。子 在本實施例中’係於同-個人孔⑴於嘴衆前後各進 一次夏測，然、❿可以理解的是，也可以更在其他位置之 孔進行量測，亦即於二個或三個人孔進行量測，如此當 有量測結果合併後可以呈現該高爐丨爐壁之36〇度完^ 115269.doc -10- 200821537 貌。 在另一實施例中，該步驟S402之第一次三維點群更包括 相對於遠兩爐1内料面丨7丨之外形，且該步驟§4〇6之該第二 次三維點群更包括相對於該高爐1内喷漿後之料面之外 ::同樣地，利用該步驟S407之比對方式後更可以得到回 彈量厚度I(圖3)。該回彈量厚度h之評估可提供有利數據 、協助現場人員與噴漿^備廠商進行責任歸屬與劃分。 f) •參考圖7 ’顯不本發明量測高爐爐壁殘厚之方法之較佳 實施例之流程圖。本實施例所量測之高爐1係為圖1之高爐 1:該方法包括以下步驟。步驟87〇1係架設一個三維雷射 知描儀於該高爐1内。與上述圖4之步驟S4G1相同，在本實 施例中，是以一型號為RIEGL LMS-Z2HH之三維雷射掃描 儀為例’且該二維雷射掃描儀係經由該高爐】之爐頂11之 人孔ui而架設於該高爐丨内位於該人孔lu附近。 二驟S7G2係啟動$二維雷射掃描儀，以利用該三維雷射 (/描儀量測取得—第-次三維點群，該第-次三維點群係 目，於該高爐1内壁之外形，如圖8中曲線81所示。要注意 本貝細例之第一次二維點群係相同於上述步驟步驟 2之第一次三維點群，且圖8之曲線μ係相同於圖$之曲 綠5 1 〇 係取得_機械尺寸模型，該機械尺寸模型係相 中於该局爐〗内壁之原始外形 始外形）(才Ρδ亥回爐1未運轉前之原 得哕機 &例中’係絰由該高爐1之原始機械 仔该機械尺寸模型（CADmodel)，如圖8曲線s2所示。 115269.d〇{ 200821537 步驟S7〇4係比對該步驟S702之第一次三維點群及該步驟 S703之機械尺寸模型，以得到該高爐1之爐壁殘厚丁5，如 圖9所示。與上述圖4之步驟S407相同，在本實施例中，係 對該第一次三維點群及該機械尺寸模型進行該疊代選取最 近點演算法。同樣地，該疊代選取最近點演算法係選取該 高爐1之爐喉12以上外形所對應之點群作為特徵點。該爐 壁殘厚Ts可由疊合後之該第一次三維點群及該機械尺寸模 型加以計算而得。該爐壁殘厚I之量測可用於評估該高爐 1之爐代壽命。另外，也可以依照該爐壁殘厚了5之分佈情 形標示出侵蝕量較嚴重部分之位置，以規劃喷漿之程序。 惟上述實施例僅為說明本發明之原理及其功效，而非用 以限制本發明。因Λ，習於此技術之人士對上述實施例進 订仏改及虼化仍不脫本發明之精神。本發明之權利範圍應 如後述之申請專利範圍所列。 【圖式簡單說明】 圖1顯示習知高爐之示意圖；After rotation and translation, it overlaps with the coordinate system to which another 3D point group belongs. In the present embodiment, since the portion below the throat 12 is significantly changed by the blasting of the refractory material, it is not suitable to select the feature point of the algorithm for selecting the nearest point of the iteration. Since the portion above the throat 12 is a constant structure before and after the shotcreting, the nearest point algorithm selects the point group corresponding to the shape of the throat of the blast furnace 1 as a feature point. The spray thickness T3 can be calculated from the group of dots after the overlap. The measurement of the thickness of the spray can be used to check whether the quality of the spray is uneven. In this embodiment, the sub-personal hole (1) is subjected to a summer test before and after the mouth. However, it can be understood that the hole can be measured at other positions, that is, two or Three manholes are measured, so that when the measured results are combined, the 36 degrees of the blast furnace wall can be presented. In another embodiment, the first three-dimensional point group of the step S402 further includes a shape corresponding to the inner surface of the two furnaces 1, and the second three-dimensional point group of the step §4〇6 is further Including the surface after the shotcrete in the blast furnace 1: Similarly, the rebound amount I (Fig. 3) can be obtained by the comparison method of the step S407. The evaluation of the rebound thickness h can provide favorable data and assist the field personnel and the spray preparation manufacturer to assign and divide the responsibility. f) • A flow chart of a preferred embodiment of the method of measuring the residual thickness of a blast furnace wall in accordance with the present invention is shown in FIG. The blast furnace 1 measured in this embodiment is the blast furnace of Fig. 1: The method comprises the following steps. Step 87〇1 is to set up a three-dimensional laser scanner in the blast furnace 1. The same as step S4G1 of FIG. 4 described above, in the present embodiment, a three-dimensional laser scanner of the type RIEGL LMS-Z2HH is taken as an example 'and the two-dimensional laser scanner is passed through the top of the blast furnace 11 The person hole ui is placed in the blast furnace and is located near the manhole lu. The second step S7G2 starts a two-dimensional laser scanner to take advantage of the three-dimensional laser (/the third-dimensional point group, the first-order three-dimensional point group, the inner wall of the blast furnace 1 The shape is as shown by the curve 81 in Fig. 8. It should be noted that the first two-dimensional point group of the present example is the same as the first three-dimensional point group of the above step 2, and the curve μ of Fig. 8 is the same as the figure. $曲曲绿5 1 〇 取得 _ mechanical size model, the mechanical size model is in the original shape of the inner wall of the furnace〗 (the original 哕 亥 回 回 回 1 1 1 1 1 & & & & & The mechanical model (CAD model) of the original machine of the blast furnace 1 is shown in the curve s2 of Fig. 8. 115269.d〇{ 200821537 Step S7〇4 is the first three-dimensional point of the step S702 And the mechanical size model of the step S703, to obtain the furnace wall residual thickness 5 of the blast furnace 1, as shown in Fig. 9. The same as the above step S407 of Fig. 4, in this embodiment, the first time The 3D point group and the mechanical size model perform the iterative selection nearest point algorithm. Similarly, the iteration selects the nearest point The algorithm selects the point group corresponding to the shape of the throat of the blast furnace 1 as the feature point. The residual thickness Ts of the furnace wall can be calculated by the first three-dimensional point group after the superposition and the mechanical size model. The measurement of the residual thickness I of the furnace wall can be used to evaluate the life of the furnace of the blast furnace 1. In addition, the position of the severely eroded portion can be marked according to the distribution of the residual thickness of the furnace wall to plan the shotcrete. The above-mentioned embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. As a result, those skilled in the art have falsified and modified the above-described embodiments without departing from the invention. The scope of the invention should be as described in the scope of the patent application described below. [Simplified illustration of the drawings] Fig. 1 shows a schematic view of a conventional blast furnace;
壁被侵韻之示 示意圖； :果之方法之較佳實施 例之流程圖；A schematic diagram of the wall being invaded; a flow chart of a preferred embodiment of the method;
圖3顯不習知咼爐在進行喷漿作業示: 圖4顯示本發料估高爐内嘴漿效果 二維點群所對應之該高爐内壁喷漿前 維點群所對應之該高爐㈣《後之㈣； 令二曲線疊合後之示意圖； 之外形； ii5269.doc •12- 200821537 圖7顯示本發明量測高爐 々皿土绞y予之方法之較佳實 之流程圖； 圖8顯示該第一次三維點群所對應之該高爐内璧之外形 及該高爐之原始機械尺寸模型；及 圖9顯示圖8中二曲線疊合後之示意圖。 【主要元件符號說明】 1 2 11 12 13 14 15 16 17 21 51 52 81 82 111 171 〇 高爐 機具 爐頂 爐喉 爐身 爐腰 爐腹 爐床 液態鐵 耐火材 曲線 曲線 曲線 曲線 人孔 料面 115269.doc -13-Figure 3 shows that the kiln is in the process of spraying. Figure 4 shows the blast furnace corresponding to the two-dimensional point group in the blast furnace. (4); Schematic diagram of the two-curve superposition; outer shape; ii5269.doc • 12-200821537 Figure 7 shows a flow chart of a preferred embodiment of the method for measuring the blast furnace slag of the present invention; The first three-dimensional point group corresponds to the shape of the inner furnace of the blast furnace and the original mechanical size model of the blast furnace; and FIG. 9 shows a schematic diagram of the two curves in FIG. [Main component symbol description] 1 2 11 12 13 14 15 16 17 21 51 52 81 82 111 171 〇 blast furnace machine top furnace throat furnace furnace waist furnace hearth liquid iron refractory curve curve curve manhole material surface 115269 .doc -13-