What should consider when choosing. using & maintaining ring die
What should consider when choosing、using、maintaining ring die?
With the growth of National economy and the living level of people, the demand of different kinds
of feed is improving, so it is with the demand of the main wearing part------the ring die, which
its quality directly affect the production cost and the feed pellet quality.
According to incomplete statistics, Ring wearing cost takes more than 30% of the total production
plant maintenance costs,and the feed pellet quality has tremendous impact on sales.Clearly,it
means a lot for feed producer to learn how to choose the right ring die.
The ring die is a wearing part with multi holes, densely covered die holes, high precision assembly
dimensions. and the wall of which is thin. When working, the feed is compressed by the rotating
extrusion ring die and the pressure roller, coming out from the inner wall outwardly through Die
hole into the strand, and then be cut to the desired length by the cutter particles. Then we make
some analysis about ring die selection, use and maintenance for your reference.
1、Selection of ring die
Ring die is generally made of carbon steel or alloy structural steel, or stainless steel by forging, machining, jig hole and heat treatment step system to do.
So far, the price of ring die sometimes high sometimes low, the main reason is the difference of material picking, process choosing and control. Some small factories producing domestic ring mold mainly composed of carbon or alloy steel by forging, die twist drill hole, and then processed by ordinary heat treatment together.Thus,this kind of ring die may emerge some problems,such as long-time process,high energy consumption, low production,bad quality of pellet. Another problem is low service life. A survey shows, the feed which produced by these ring dies have high iron content, which greatly affects the feed formula, the result mainly caused by poor wear resistance.
With the continuous development of market economy, China joining the WTO, only cheap feed got competitiveness on the market. For feed producers to reduce production costs and improve the quality of feed pellets is urgently needed, and these qualities are largely determined by the level of quality ring die.
According to ring die working conditions, feed producers should use those advanced production plant who can have reasonable selection and reasonable process in producing ring die.
You’d better use stainless steel ring die, ring die made of stainless steel forging stock, is the essence of high quality ring mold life assurance;
The die hole should use gun drilling process, the use of multi-position rifle drill holes ensure the smooth bore die without forming a crooked hole,so to achieve faster, better quality particles (particle surface is smooth, uniform, small powder rate, etc.).
Should choose the ring die who got by vacuum heat treatment, vacuum heat treatment of the ring mold is a further guarantee of the quality of the previous step process, which guarantees high wear resistance, high strength, and the smoothness of the orifice ring mold materials were effective protection (to avoid the oxidation of the die hole).
二、環模的使用
首先，在選用優質環模的前提下，應根據生產飼料品種、配方及產量選用合適的模孔形式、開孔率及壓縮比（壓縮比=模孔的有效長度/模孔直徑）。一般來說，直形孔和階梯形孔適于加工配合飼料；外錐形孔適合加工脫脂糠等高纖維的飼料；內錐形孔宜加工草粉料類比重輕的飼料。在保證環模強度的前提下，盡量提高環模的開孔率，對于有些品種的飼料，在保證合理壓縮比的條件下，環模過于壁薄，以致環模強度不夠，生產中會出現爆模現象，此時應當在保證模孔有效長度的前提下，增加環模的厚度和增開減壓孔。通常來說，含谷物高的配合飼料宜選之間的壓縮比；熱敏感飼料及尿素飼料宜選用5-8之間的壓縮比；含天然蛋白質高的濃縮飼料適于選用5-11之間的壓縮比；奶牛配合飼料適宜選用7~15之間的壓縮比。另外還可以在考慮飼料基本配方后，依據生產者自己要求的飼料品質調整具體的壓縮比，比如選用稍低的壓縮比對于增加產量、降低能耗、減輕環模的磨損等有利，但是這樣一來將會降低飼料的品質，如顆粒不夠結實，外觀松散長短不一，飼料的粉化率高，反之，則對顆粒品質有利（顆粒外觀光滑而有光澤，粉化率小），但會增加產品的生產成本。
其次，環模與壓輥之間工作間隙合理與否對環模的有效使用具有重要影響。一般來說，環模與壓輥之間的間隙為0.1-0.3之間，以實踐經驗來說，用手扳動環模旋轉的同時，壓輥達到似轉非轉的狀態為佳。那么，如何調整環模與壓輥之間的間隙呢？通過我們的實踐經驗得知，當新模裝機后，首先，松動壓輥調節螺栓將壓輥調整到壓輥外圓面緊靠環模內圓面的狀態；其次，依次調整壓輥偏心軸使各壓輥與環模之間間隙適當，預緊調節螺栓，扳動環模，逐步調節間隙，使壓輥達到似轉非轉的工作狀態，最后緊固調節螺栓。當新模裝機時，通常要求環模與壓輥之間間隙比您所需要的稍大，這有利于新環模與舊輥之間的平穩過渡，等新模與舊輥完成一定的磨合期以后，可以將間隙調整到您所需要的間隙。在使用中，都是保環模而犧牲壓輥，因為環模的價格是壓輥價格的十幾倍甚至幾十倍，所以在使用中，在選用合理間隙的情況下，壓輥的硬度不能太高，也就是說，壓輥的耐磨性不能比環模的耐磨性高。
環模在生產過程中，對所使用的物料要求進行必要清理，避免物料混有大塊砂石、砂粒、鐵塊、螺栓及鐵屑等硬顆粒。因為這些夾雜加速了環模的磨損，而且大量的、大硬夾雜將造成環模多次受力，使環模產生疲勞，當某次受力超過環模的強度極限時，環模將出現爆模現象。
最后，操作者在新裝或更換環模時，對于通過錐面裝配的環模來說，新裝模時，要求避免造成錐面的碰傷及刮傷，并對其錐面及其配合傳動輪緣錐面進行必要清理，涂油裝配。更換環模時，拆卸，不碰傷及刮傷錐面，涂油保護。對于經常需更換環模的顆粒機來說，要求定期對傳動輪緣進行檢查，防止其過度磨損而導致模具定心銷的斷裂，因為過度的磨損將會影響環模與輪緣之間的配合，配合不緊，當環模工作時將對模具定心銷產生剪切力而導致斷裂，當產生這種情況后，千萬不要誤認為是銷的強度不夠而換成高強度的銷，最終只能導致環模損壞和安全銷經常性的斷裂。因此，對環模的配合錐面及配合的傳動輪緣的錐面進行保護和定期的檢查是相當必要的。對于抱箍式裝配的環模來說，對其裝配面及其配合的元件的保護與檢查也是相當必要的。當壓輥使用一段時間后，會出現磨損現象，影響了與環模的配合精度，從而影響了環模的生產產量，應對其進行必要的修理或更換新的環模。
三、環模的基本維護
俗話說，磨刀不誤砍柴工。對環模進行合理的維護保養是環模經濟、有效使用的一部分。
在生產過程中，操作者經常發現，環模在使用過程中，通常會出現堵塞、磨損、封口及內 翻等現象，這時，如果不對其進行必要維護，將造成產量降低，能耗增加，甚至不出料等現象。此時，對環模進行基本維護的方法是，先將環模工作內圓面進行磨平，然后進行倒角。
當更換環模時，要求趁熱模將含油物料充填模孔，以便下次生產時使環模達到最佳狀態。
綜上所述，只有對環模進行正確選用、合理使用和有效的維護，才能降低成本，提高效率，創造顆粒品質，增強產品市場競爭力，迎接挑戰，為企業創造更多的經濟效益。