風冷加熱器內膽(鑄鋁)主要適用於完全擠壓部件,由幾個帶有降溫係統連接的加熱器組成,根據應用要求,該主要部件在佈局和數目上能被並成一個係統,由於擠壓圓柱筒完全被覆蓋,有一個統一的溫度變化,再擴大了熱輻射麵,而使得效能提高。又可消除因擠壓而導緻的摩擦熱,根據生産所需不同的溫度,由幾個連接而成的帶狀加熱器組成,用陶瓷散熱器連接,然後用一個可單獨固定的冷卻外罩安裝,可用風扇連接盒和空氣出口裝置安裝,該帶狀加熱器可單獨替換。加熱器能承受的高溫度500℃,是目前國內外擠出機,註塑機料筒熱門的加熱冷卻裝置。此款加熱器推薦給對性價比要求高的客戶。
目前市場上提供多種加熱器配置。用於塑料機械料筒加熱的有三類常見加熱器:雲母、陶瓷關節及金屬鑄造加熱器。
一、雲母加熱器
雲母加熱圈大約厚5mm,能適應多種幾何形狀和特殊部件,如孔和凹槽,但雲母用於加熱器絕緣層時,雲母溫度不應超過550℃。當溫度超過該水平,粘合劑就開始退化,絕緣強度也將變弱,因此加熱器的護套溫度不能超過450℃。以及雲母加熱器的標準功率密度隻有3W/cm2。目前雲母加熱器已很難滿足越來越多塑料工藝的要求。
二、陶瓷加熱器
陶瓷具有耐高溫絕緣性,因此陶瓷加熱器可處理760℃的溫度。陶瓷加熱器的柔軟可形成各種加熱器直徑。遺憾的是,陶瓷的優點也是其弱點,由於它能存儲元件金屬絲産生的熱量,因此人們很難控製陶瓷加熱器的溫度。這會導緻不必要的廢料,在塑料生産工藝的較早階段,這一點尤其突出。另外,陶瓷加熱器在拆裝過程中容易損壞,特別是升溫以後,加熱器會變得比較鬆散,給安裝帶來不便。陶瓷加熱器不能受到汙染這一特性也限止了這類加熱器的應用範圍。
三、 金屬鑄造加熱器
金屬鑄造加熱器是將一定形狀的加熱管澆鑄在銅、鋁或鐵等材料中,這類加熱器體積較大,製作成本高,生産過程中能耗高,對環境有汙染,以及使用時熱效率較低,國外已較少採用此類加熱器(除非特定要求)。
四、新型氧化鎂絕緣加熱圈
氧化鎂絕緣加熱圈是一種高性能的加熱器,採用導熱性能比傳統的雲母和陶瓷更高的高純氧化鎂作為絕緣材料,一層薄薄的緻密的氧化鎂填充在電熱絲與金屬外套之間,電熱絲的熱量迅速傳遞給被加熱物體,降低了電熱絲的溫度,大大的提高了加熱器的使用壽命。氧化鎂的耐高溫性和壓縮層具有好的導熱性能和絕緣強度,氧化鎂絕緣加熱圈的功率密度達到15W/cm2,使用溫度可達760℃,利用該性能可製造加熱器以適應現代的塑料製造工藝。
考慮加熱器類型時,必須了解每種類型加熱器的性能和局限。零件的幾何形狀、溫度和加熱時間要求確定機器所需加熱器的類型。
每個類型加熱器都具有與衆不同的特點。當加熱器加熱零件時,由內部絕緣體提供必要的絕緣強度,所以區分這些加熱器的材料是內部絕緣體。每個加熱器中的絕緣體對加熱器的壽命和性能具有重要影響。
現代塑料加工工藝對加熱器的要求會更高,對溫度的均勻性、熱反應性能、特殊材料所需的高溫要求以及倍受關註的熱效率,氧化鎂絕緣加熱器因其出色導熱性能和絕緣強度,在加熱器市場一定會佔顯著地位。
Currently on the market offers a variety of heater configurations. There are three common types of heaters: mica, ceramic joints and metal casting heater for plastic machinery barrel heating.
●Mica heater:
Mica heating coil about the thickness of 5mm, can adapt to a variety of geometric shapes and special parts, such as holes and grooves, but mica for the heater insulating layer, mica temperature should not exceed 550℃. When the temperature exceeds this level, the adhesive begins to degenerate, the insulation strength is becoming weaker, so the heater sheath temperature must not exceed 450 ℃. Mica heater standard power density 3W/cm2. The mica heater has been difficult to meet the requirements of more and more plastic process.
●The ceramic heater:
Because of the high temperature ceramic insulation, the ceramic heater can be processed to a temperature of 760℃. The. The soft ceramic heater may be formed various heaters diameter. Unfortunately, the advantages of the ceramic is also its weakness, due to the heat generated can store element wire, so it is difficult to control the temperature of the ceramic heater. This causes unnecessary waste, in plastic an earlier stage of the production process, which is particularly prominent. In addition, the ceramic heater is easy to damage during disassembly, especially after the temperature, the heater will become more loose, to install the inconvenience. The ceramic heater of this feature can not be contaminated and also limiting the scope of application of such a heater.
●The metal casting heater:
Is a certain shape of the heating tube cast in copper, aluminum or iron material, this type of heater sizes, high production costs, high energy consumption in the production process, the pollution of the environment, as well as a lower thermal efficiency in the use of foreign been less used to this type of heater (unless a specific request).
●The new magnesium oxide insulated heating coil:
Magnesium oxide insulated heating coil is a high performance heater, thermal conductivity than the traditional mica and ceramic higher purity magnesium oxide as the insulating material, a thin layer of dense magnesium oxide filled in electric wire and metal jacket between the heat of the heating wire quickly passed to the object to be heated, reducing the temperature of the heating wire, greatly improve the life of the heater. Magnesium oxide of high temperature and compression layer has excellent thermal conductivity and dielectric strength, magnesium oxide insulated heating coil power density 15W/cm2 use temperatures up to 760℃, the use of the performance can be manufactured efficient heater to adapt to the modern plastic manufacturing process.
Considering the type of heater, you must understand the performance and limitations of each type of heater. Part geometry, temperature and heating time required to determine the type of machine desired heater.
Each type heater has distinctive features. When heated by a heater parts, by the internal insulator to provide the necessary dielectric strength, so the only material to distinguish these heater internal insulator. The insulator of each heater has an important impact on the life and performance of the heater.
Modern Plastics Processing and process requirements of the heater will be higher, temperature uniformity, thermal reaction performance, high temperature requirements of special materials required, and the thermal efficiency of a well-focused, magnesium oxide insulation heater because of its excellent thermal conductivity and dielectric strength will figure prominently in the heater market.