機械基礎

本書是為了適應職業教育的培養目標和教育特點，遵循“以必須、夠用為度”和“強化應用、培養技能”的原則，突出中職教育特色而編寫的。

本書共分7 章，內容包括：構件的靜力分析、桿件的基本變形、機械工程材料、常用機構、機械傳動、支承與連接零部件和液壓傳動系統。每章前面有學習目標，後面有本章小結，並附有大量的練習題供讀者練習。

本書適用於機械、機電類等應用技術類專業的學生使用，也可作為相關行業人員的培訓用書。

緒論·································································································································· 1

第1 章 構件的靜力分析······························································································· 5

1.1 靜力學基本概念及靜力學公理······································································· 5

1.1.1 力的概念······························································································· 5

1.1.2 剛體的概念··························································································· 6

1.1.3 平衡的概念··························································································· 7

1.1.4 靜力學公理··························································································· 7

1.2 約束與受力圖································································································ 10

1.2.1 幾種常見的約束················································································· 10

1.2.2 受力分析與受力圖············································································· 13

1.3 平面匯交力系································································································ 16

1.3.1 平面匯交力系合成的幾何法······························································ 16

1.3.2 平面匯交力系合成的解析法······························································ 17

1.3.3 平面匯交力系的平衡條件·································································· 19

1.4 力矩和力偶···································································································· 21

1.4.1 力對點之矩························································································· 21

1.4.2 合力矩定理························································································· 21

1.4.3 力偶的概念························································································· 22

1.4.4 力偶矩································································································· 23

1.4.5 力偶的性質························································································· 23

1.4.6 平面力偶系的合成············································································· 24

1.4.7 平面力偶系的平衡············································································· 24

1.5 平面任意力系································································································ 26

1.5.1 力線平移定理····················································································· 26

1.5.2 平面任意力系向一點的簡化······························································ 27

1.5.3 平面任意力系的平衡條件與平衡方程·············································· 30

1.5.4 平面平行力系的平衡········································································· 31

1.5.5 平面任意力系平衡方程的應用·························································· 34

1.5.6 物體系統的平衡················································································· 36

【本章小結】········································································································ 40

【習題】················································································································ 41

第2 章 桿件的基本變形····························································································· 48

2.1 材料力學的基本概念···················································································· 48

2.2 拉伸與壓縮···································································································· 50

2.2.1 軸向拉伸與壓縮基本變形及相關概念·············································· 50

2.2.2 軸向拉伸與壓縮的應力分析······························································ 53

2.2.3 軸向拉伸與壓縮時的強度計算·························································· 56

2.2.4 拉伸與壓縮時的變形········································································· 59

2.2.5 靜載荷作用下材料的力學性能·························································· 62

2.3 剪切和擠壓···································································································· 66

2.3.1 剪切的實用計算················································································· 67

2.3.2 擠壓的實用計算················································································· 68

2.4 圓軸的扭轉···································································································· 70

2.4.1 外力偶的計算····················································································· 71

2.4.2 扭矩與扭矩圖····················································································· 71

2.4.3 圓軸扭轉時的應力分析····································································· 74

2.5 直梁的彎曲···································································································· 77

2.5.1 平面彎曲的基本概念及梁的類型······················································ 77

2.5.2 梁彎曲時的內力和內力圖·································································· 78

2.5.3 梁的彎曲正應力················································································· 83

2.5.4 等截面梁的強度計算········································································· 85

2.5.5 提高彎曲強度的主要措施·································································· 86

【本章小結】········································································································ 88

【習題】················································································································ 89

第3 章 機械工程材料································································································· 94

3.1 金屬材料的力學性能···················································································· 94

3.1.1 強度與塑性························································································· 95

3.1.2 硬度····································································································· 95

3.1.3 衝擊吸收功和衝擊韌度····································································· 96

3.1.4 金屬的疲勞強度················································································· 97

3.2 鋼鐵材料········································································································ 97

3.2.1 碳素鋼································································································· 97

3.2.2 合金鋼································································································· 99

3.2.3 鑄鐵··································································································· 102

3.3 鋼的熱處理·································································································· 103

3.3.1 金屬及合金的晶體結構··································································· 103

3.3.2 鐵碳合金的基礎知識······································································· 106

3.3.3 鋼的熱處理基本原理······································································· 109

3.3.4 鋼的熱處理工藝··············································································· 112

3.3.5 鋼的表面熱處理··············································································· 114

3.4 有色金屬材料······························································································ 115

3.4.1 銅及銅合金······················································································· 115

3.4.2 鋁及鋁合金······················································································· 116

3.5 非金屬材料·································································································· 117

3.5.1 工程塑料··························································································· 117

3.5.2 橡膠··································································································· 118

3.5.3 陶瓷··································································································· 118

3.5.4 複合材料··························································································· 119

【本章小結】······································································································ 120

【習題】·············································································································· 120

第4 章 常用機構······································································································ 122

4.1 機構和機構運動簡圖·················································································· 122

4.1.1 機構的組成······················································································· 122

4.1.2 機構運動簡圖··················································································· 124

4.2 平面連桿機構······························································································ 124

4.2.1 鉸鏈四桿機構的基本形式································································ 125

4.2.2 平面四桿機構的其他形式································································ 128

4.2.3 平面四桿機構的基本特性································································ 130

4.3 凸 輪 機 構································································································ 135

4.3.1 凸輪機構的分類··············································································· 136

4.3.2 從動件的常用運動規律··································································· 138

4.3.3 盤形凸輪輪廓曲線的設計································································ 141

4.4 間歇運動機構······························································································ 144

4.4.1 棘輪機構··························································································· 144

4.4.2 槽輪機構··························································································· 146

【本章小結】······································································································ 147

【習題】·············································································································· 148

第5 章 機械傳動······································································································ 150

5.1 帶傳動········································································································· 151

5.1.1 帶傳動的主要類型及工作原理························································ 151

5.1.2 摩擦型帶傳動的主要特點和應用···················································· 152

5.1.3 帶傳動的受力分析··········································································· 153

5.1.4 帶傳動的彈性滑動與傳動比···························································· 155

5.1.5 V 帶與V 帶輪·················································································· 156

5.1.6 普通V 帶傳動的設計計算簡介······················································· 160

5.1.7 帶傳動的張緊和維護······································································· 164

5.2 齒輪傳動······································································································ 165

5.2.1 齒輪傳動的類型及特點··································································· 165

5.2.2 漸開線齒廓······················································································· 167

5.2.3 漸開線標準直齒圓柱齒輪的主要參數和幾何尺寸························· 170

5.2.4 漸開線標準直齒圓柱齒輪的嚙合傳動············································ 173

5.2.5 漸開線齒輪的加工方法··································································· 177

5.2.6 平行軸標準斜齒圓柱齒輪傳動························································ 179

5.2.7 直齒圓錐齒輪傳動··········································································· 183

5.2.8 齒輪的材料與齒輪的失效形式························································ 185

5.2.9 齒輪的結構及齒輪傳動的潤滑························································ 188

5.3 蝸桿傳動······································································································ 190

5.3.1 蝸桿傳動的類型和特點··································································· 190

5.3.2 圓柱蝸桿傳動的主要參數和幾何尺寸············································ 191

5.3.3 蝸桿傳動的失效形式和常用材料···················································· 195

5.3.4 蝸輪迴轉方向的判定······································································· 196

5.4 齒輪系········································································································· 196

5.4.1 齒輪系的功用和分類······································································· 196

5.4.2 定軸齒輪系傳動比的計算································································ 198

5.4.3 行星齒輪系傳動比的計算································································ 201

【本章小結】······································································································ 203

【習題】·············································································································· 205

第6 章 支承與連接零部件······················································································· 209

6.1 軸················································································································· 210

6.1.1 軸的分類和軸的材料······································································· 210

6.1.2 軸的失效形式與設計準則································································ 212

6.1.3 軸的結構設計··················································································· 214

6.2 軸承············································································································· 218

6.2.1 滾動軸承的結構、特點和類型························································ 218

6.2.2 滾動軸承的代號及類型選擇···························································· 221

6.2.3 滾動軸承的組合設計······································································· 225

6.3 軸轂連接······································································································ 228

6.3.1 鍵連接的類型··················································································· 229

6.3.2 鍵的選用··························································································· 230

6.3.3 花鍵的類型、特點和應用································································ 232

6.4 螺紋連接······································································································ 232

6.4.1 螺紋的類型、特點和應用································································ 232

6.4.2 螺紋連接的基本類型······································································· 235

6.4.3 標準螺紋連接件··············································································· 236

6.4.4 螺紋的預緊與防松··········································································· 238

6.5 聯軸器和離合器·························································································· 239

6.5.1 聯軸器······························································································· 240

6.5.2 離合器······························································································· 243

【本章小結】······································································································ 245

【習題】·············································································································· 245

第7 章 液壓傳動系統······························································································· 247

7.1 液壓傳動概述······························································································ 247

7.1.1 液壓傳動的工作原理······································································· 247

7.1.2 液壓傳動系統的組成······································································· 248

7.1.3 液壓傳動的特點··············································································· 249

7.1.4 液壓系統的圖形符號······································································· 249

7.2 液壓傳動的基礎知識·················································································· 250

7.2.1 液壓油的特性及選用······································································· 250

7.2.2 液壓傳動的兩個重要參數································································ 250

7.3 液壓元件······································································································ 253

7.3.1 液壓泵······························································································· 253

7.3.2 液壓缸······························································································· 256

7.3.3 液壓控制閥······················································································· 259

7.3.4 液壓輔件··························································································· 267

7.4 液壓基本迴路······························································································ 269

7.4.1 方向控制迴路··················································································· 269

7.4.2 壓力控制迴路··················································································· 270

7.4.3 速度控制迴路··················································································· 271

7.4.4 多缸動作迴路··················································································· 273

7.5 液壓系統實例······························································································ 274

【本章小結】······································································································ 275

【習題】·············································································································· 276

參考文獻······················································································································ 280