Die Cooling 模具冷卻
Oil Cooling 油冷卻 • Oil is passed through channels in the cavity inserts 油流過模具的管道 • High temperature oils are now available 高温導熱油 • Lower heat capacity and transfer coefficient than water熱容量和傳熱系數比水小 • Channels must be larger in diameter and length 管道口徑和長度要大些 • Medium power cooling 冷卻功率中等
Die Pre Heating 模具預熱
Gas Heating氣體加熱 Advantages好處 • Low energy cost低能源成本 Disadvantages缺点 • • • • Heats from the outside of die外部加熱 Hard to automate難於自動化 Labour intensive人手操作 Higher chance of damaging dies容易損害 模具
Manual Temperature Control人手溫度控制
• Requires constant coolant flow 固定冷卻流量 • Coolant flow rate has minimal effect 難於控制流量 • Difficult to balance the heat flow 難於平衡熱流 • Cycle time adjusted to control quality 要調節生產週期來控制質量 • Difficult to design (balanced cooling) 難於設計(平衡冷卻) • Dies cool when cycle stops 中斷生產時模具不斷冷卻
Measuring Die Temperature測量模溫
Hand Held Thermocouple 手提電熱偶 Hand Held Infra-red 手提紅外線測温
• Not suitable for continuous production不適合連續生產 • Wide fluctuations likely數据波動大
Die Temperature Control Options for Die Casting 壓鑄模温度控制方法
G. L. Wilson
Die Casting Seminar, Shenzhen, 2004
Die Temperature模具温度
• Significant process variable 重要的工藝參數 • Effects casting quality 影响鑄件質量 • Effects production rate 影响生產效率 • Effects casting cost 影响鑄件成本
Thermocouple Connections 熱電偶接頭
• Metal casing 金属外殼 • Metal cover with spring hinge 彈簧鉸金屬蓋 • Excludes dust, oil, flash 防塵、油、金属飞濺 • No moving wires 無可移动線 • Ensures reliability 保証可靠性
Relative Cooling Power相對冷卻功率
Cooling Power
冷卻功率
Natural自然 Air 空氣
Oil油
Spray噴塗
Water水
Die Thermal Design模熱設計
• Calculate the heat to be removed from each segment of the die.計算每個模熱區域需要帶走的熱量 • Manual calculation, Basic program like DC-CALC or using Graphical software. 人手計算，dc-calc程式計算，圖形軟件計算 • Select the coolant fluids (air, oil, water or a combination). 選擇冷卻媒體(空氣，油，水或組合) • Locate and size the cooling channels in the die. 放置冷卻管道及决定尺寸 • Select the method of die heating 選擇加熱方式
Die Pre Heating 模具預熱
Oil Heating油加熱 Advantages好處 • Heats from inside the die從模內加熱 • Heats the cavity inserts directly直接加熱模芯 • Can pre-heat out of machine Disadvantages缺点 • Capital investment設備投資 • Possible oil leaks有機會漏油
Die Cooling 模具冷卻
Natural Cooling 自然冷卻
• Occurs in all Die Casting dies 發生在所有金屬模 • Significant in Low Pressure and Gravity Die Casting 對低壓及重力鑄造模很重要 • For high pressure Die Casting it accounts for between 5% and 10% of Die Cooling power 佔壓鑄模5-10%冷卻功率
Die Pre Heating 模具預熱
Warm-up shots 打料加熱 Advantages好處 • No equipment needed無須任何設備 Disadvantages缺点 • Makes defect castings制造廢品 • High thermal shock to die surface模具表面 受熱冲擊 • Re-melting required需要翻熔廢品 • Higher chance of shipping a defect有機會 混入正品
Die Pre Heating 模具預熱
Electric Heating電熱 Advantages好處 • Heats from inside the die從模內加熱 • Efficient heating效率高 • Can pre-heat out of machine Disadvantages缺点 • Needs to be added to each die 需要每套模具安裝
Thermocouples Embedded in the Die 熱電偶藏於模內
1. 3.
2.
4.
K-type Thermocouples熱電偶
• Good temperature range合 適的温度笵圍 • Resistance to corrosion抗 腐蝕 • Low cost成本低 • Readily available容易購買 • Small diameter細小口徑 • Can be bent into position可 彎曲藏入 • Easily fitted into wiring channels易於切入管道
Measuring Die Temperature 測量模溫
Thermocouples Embedded in the Die 熱電偶藏於模內
• Suitable for continuous production 適合連續生產 • Accurate measurement 數据測量準確 • Measure key internal locations 測量模內關鍵位置 • Use for automatic control 可用於自動控制
Die Temperature Range模溫笵圍
Optimum適當
Temperature温度
Upper Limit 上限 Lower Limit 下限
Ambient環境
Die模具
Metal金屬
Die Pre Heating模具預熱
• Die temperature starts at ambient 從室溫開始加熱 • Increase to operating temperature 加熱至操作溫度 • Four methods available四種方式 • • • • Warm-up shots打料加熱 Gas heating氣體加熱 Oil heating油加熱 Electric heating電熱
Continuous Measurement of Die Temperature 模温連續性測量
• Opens a window inside the die 可透視模內情况 • Provides operator visibility 讓操作人員了解 • Identify operating range 判定操作笵圍 • Set control limits 設定控制上下限 • Identify inadequate cooling 判定不适當冷卻 • Identify over-cooling 判定過度冷卻
Die Cooling 模具冷卻
Spray Cooling 噴塗冷卻
• Water and die release agents are sprayed on to the die parting face水和脫模劑噴塗於模具分模面上 • Can remove heat significant quantities of heat 可帶走大量熱量 • Difficult to control 難於控制 • Can cause porosity and increased heat checking 會引致氣孔和增加熱裂
Die Cooling 模具冷卻
Air Cooling 空氣冷卻 • Air is passed through cooling channels or around die surfaces 空氣流過冷卻管道或模具表面 • Useful in Low Pressure Die Casting 特別適用於低壓鑄造 • Can be used in long cores which are difficult to cool with water可用在難於水冷的長模芯 • Low power cooling 冷卻功率低