電大數控加工工藝期末重點復習考試試題及詳細答案參考小抄-資料下載頁

　　

【正文】 刀具、又能測量車削刀具切削刃的徑向和軸向坐標位置。 試述加工中心的工藝特點有哪些？ 答： ① 可減少工件的裝夾次數 ② 可減少機床數量，并相應減少操作工人，節省占用的車間面積。 ③ 可減少周轉次數和運輸工作量，縮短生產周期。 ④ 在制品數量少，簡化生產調度和管理。 ⑤ 使用各種刀具進行多工序集中加工。 ⑥ 若在加工中心上連續進行粗加工和精加工，夾具既要能適應粗加工時切削力大、高剛度、夾緊力大的要求，又須適應精加工時定位精度高，零件夾緊變形盡可能小的要求。 ⑦ 應盡量使用剛性好的刀具，并解決刀具的振動和穩定性問題。 ⑧ 多工序的集中加工，要及時處理切屑。 ⑨ 在將毛坯加工為成品的過程中，零件不能進行時效，內應力難以消除。 ⑩ 技術復雜，對使用、維修、管理要求較高，要求操作者具有較高 的技術水平。 第 8章 數控線切割加工工藝 一、單項選擇題 若線切割機床的單邊放電間隙為 ，鉬絲直徑為，則加工圓孔時的間隙補償量為 ( B )。 （ A） （ B）－ （ C） （ D） 線切割機床不能加工材料為 ( B )。 （ A） 合金鋼 （ B） 非金屬 （ C） 碳素鋼 （ D） 不銹鋼 電極絲直徑 d與拐角半徑 R、放電間隙 ?的關系為（ A ）。 （ A） d≤2（ R?） （ B） d≥2（ R?） （ C） d≤（ R?） （ D）d≥（ R?） 脈沖寬度加大時，線切割加工的表面粗糙度（ A ） （ A） 增大 （ B） 減小 （ C） 不確定 （ D） 不變 下列敘述中，（ A ）不是線切割加工的特點。 （ A） 要求刀具有足夠的剛度 （ B） 刀具簡單 （ C） 材料利用率高 （ D） 可以加工高硬度金屬材料 二、判斷題（ 正確的打 √，錯誤的打 ） 電極絲過松會造成工件形狀與尺寸誤差。（ √ ） 線切割加工的表面粗糙度主要取決于單個脈沖放電能量大小，與走絲速度無關 .( ) 線切割加工時，凹 角處可以清角。（ ） 在相同表面粗糙度的情況下，用線切割加工的零件的耐磨性比機械加工的好。（ √ ） 線切割加工時，工件的變形與切割路線有關。（ √ ） 三、簡答題 數控線切割加工的主要工藝指標有哪些？ 答：（ 1）切割速度（ 2）表面粗糙度（ 3）電極絲損耗量（ 4）加工精度 影響 線切割加工指標的電參數有哪些？ 答： ① 脈沖寬度② 脈沖間隔③ 開路電壓④ 放電峰值電 流⑤ 放電波形⑥ 極性 ⑦ 變頻、進給速度 數控線切割加工對工件裝夾的基本要求是什么？ 答： ① 工件的裝夾基準面應清潔 無毛刺。 ② 夾具精度要高。 ③ 裝夾工件的位置要有利于工件的找正，并能滿足加工行程的需要，工作臺移動時，不得與絲架相碰。 ④ 裝夾工件的作用力要均勻，不得使工件變形或翹起。 ⑤ 批量加工時最好采用專用夾具，以提高效率。 ⑥ 細小、精密、薄壁工件應固定在輔助工作臺或不易變形的輔助夾具上。 Visafree policy brings Chengdu biz, tourism boost. Making national headlines several times, Chengdu39。s 72hour visafree policy has attracted wide attention from both Chinese and foreign experts and businessmen since it took effect on Sept 1 last year. The program permits citizens from 51 countries and regions including the United States, Australia, Canada and Japan who have valid visas and flight tickets to a third country to spend three days in the city. The capital of Sichuan province is the first city in the western region of China to offer foreign tourists a threeday visa and the fourth nationwide to adopt the policy following Shanghai, Beijing and Guangzhou. Li Zhiyong, deputy dean of the tourism institute at Sichuan University, said the move contributes to a large increase in the number of overseas tourists and raises the city39。s level of internationalization. The policy will also bring direct economic revenue, Li said. Chengdu has many cultural legacies and is also a paradise for panda lovers with the world39。s largest breeding and research center. Three days are long enough for foreign visitors to visit those iconic tourist spots, he noted. The city is home to the remains of the Jin sha civilization that dates back more than 3,000 years as well as the Qing cheng Mountains and the Du jiang yan irrigation system. Qing cheng has long been recognized as the birthplace of Taoism, China39。s ancient indigenous religion, while Du jiang yan is considered to be the oldest functioning watercontrol project in the world. Chengdu ranked third in tourist facilities, management and services among 60 Chinese cities in a customer satisfaction survey released last year. But, Li added that efforts are still needed to develop more tourism products, improve English services and provide accurate translation of traffic signs and scenic billboards. Zhao Yun, chairwoman of British Chamber of Commerce Southwest China, told China Daily that his colleagues found the policy very convenient. A British client once flew here and stayed for just one day to check her ordered goods, she said. Zhao was born in Shanxi province, but she has lived in Chengdu for more than 10 years. My life was like a running race moving from place to place. I also lived in Beijing and Shanghai before, she said. But Chengdu is a place that you never want to leave once settling down. It is now my second hometown, she said. If the environment is further improved, the city will attract more people to visit and live, with the 72hour visafree policy and pelling conditions in transportation, culture, climate and cuisine, he said. Foreigners also gave positive feedback on the policy. A spokesman from Dell Inc said the pany has a global hub of operation in Chengdu, so the threeday visa has an immediate and positive influence on the pany39。s business development. Rudy Buttignol, president of the public broadcasting pany in British Columbia, Canada, said his work requires frequent travel to Chengdu and the policy makes the trips easier. Data from the city39。s public security bureau shows some 100 foreign visitors enjoyed the 72hour policy by the end of March, most of them from the United States, the United Kingdom and Germany. Chengdu also reported robust growth in its overall tourist industry last year. Official statistics show that it received some 150 million tourists last year, an increase of 28 percent from 2021. Around million came from abroad, an increase of 12 percent. Total revenue from tourism surpassed 133 billion yuan ($). During his visit to Kazakhstan in September, Chinese President Xi Jinping proposed that China and Central Asia join hands to build a Silk Road economic belt to boost cooperation. The idea has been widely echoed in Central Asian countries, being an encouraging blueprint for Chinese areas along the Silk Road that has linked Asia and Europe for more than 2,000 years. In the next three weeks, China Daily reporters w ill travel through the belt in China and in Kazakhstan, Uzbekistan and Turkey. They w ill show the progress and expectations of the countries, businesses and peoples on the route. Shaanxi the start of the ancient Silk Road has positioned itself as the new starting point for the development of the Silk Road Economic Belt, w hich will strengthen China39。s cooperation with Central Asian countries, a se