Granulating machine is the key equipment in feed production process, while the ring mould is the heart part work granulator, one of the parts is the most easy to weargranulator. Research on the causes of failure of ring die ring die, improve theconditions of use, to improve product quality and yield, reduce energy consumption,reduce the production cost greatly influence.

Ring die during normal operation, there are always and friction between the materials.With the increase of production materials, die wear, and eventually lead to failure.One of the indicators to measure the performance of the ring die so that production.However, in the actual production process, the majority of ring die before reaching thetheoretical capacity will fail. As the ring mould is expensive, it will cause some loss for the user. This paper analyzes the failure reason of the ring die, put forward suggestions to manufacture, use conditions of die.

Failure analysis of ring die:

From the ring die actual failure phenomenon of view, can be divided into 3 categories.The first class: ring die after a period of time, discharging the hole wall, diameter increases, the production of pellet diameter exceeds the specified value and failure;second: Die inwall wear, uneven inner surface is serious, the feed flow, dischargedecreased and stop using third kinds of:; ring die inwall wear, the diameter increases,the wall thickness is reduced, and the outlet hole wall also with wear, so that thedischarging hole wall thickness between continuous thinning, decreased the structural strength, the discharge hole diameter increases to allow the specified value (i.e.before the first failure phenomenon before) in the section, the most dangerous on thefirst cracks and expanding, until the crack extends to larger scope and lead to circular mould invalidation. The 3 kinds of failure phenomenon of substantive reasons, to sum up, the first is abrasive wear, followed by fatigue failure.

Abrasive wear

Wear for many reasons, divided into normal wear, abnormal wear. Normal wear is mainly due to material composition, particle size, powder feed quality etc.. The condition of normal wear ring die there is axial uniform wear, causes the ring die holeenlargement, wall thickness. The main reason: not normal wear roller adjustable too tight, and die gap is small, each wear; spreader angle is not good, resulting in unevendistribution of materials and parts to wear; fell into a metal die wear. In this case, the ring mould with multiple irregular wear, for the drum shaped. Concrete analysis is as follows:

(1) the granularity of raw materials

Raw material grinding fineness to moderate uniform, because raw material grindingfineness decides the feed composition of surface area, smaller particle size, surface area is larger, the material absorb steam water more quickly, in favor of temperingand particle forming. Particle through thick, will increase the wear of die, and result in decreased productivity, energy consumption. General requirements for raw materialsafter crushing to all through 8 mesh sieve surface, 25 mesh sieve material shall not be greater than 35%. The crude fiber content of high material, adding a certain amount of oil, the granulating process, can reduce the friction between the material and thering die, is conducive to the material through the die, and the forming of granuleappearance is smooth.

(2) the raw materials contain complex

In the material containing sand and iron too many impurities, will accelerate the wear and tear, die so, raw material cleaning work is very important. At present, most feed mills attached more importance to the removal of iron impurity in raw materials, ironmaterial on the die, pressure roller and the equipment will cause severe damage. Theremoval of soil type impurities do not attach importance to. This should arouse the attention of the user granulating machine.

2 fatigue damage

Granulating machine die for a porous ring parts, poor working conditions, in the process of using long withstand the pressure and material friction roller, the bendingstress and contact stress. But the stress is not affect the service life of die factors, its main failure from fatigue failure.

Ring die is usually made of carbon steel or stainless steel (alloy) by forging, cutting,drilling, heat treatment and other steps. Ring die during drilling, the porous gun drill processing, to ensure the quality of hole. Heat treatment, should adopt vacuumquenching equipment, can avoid the carbon removal of surface oxidation occurs frequently in the ordinary equipment in, resulting in higher hardness.

Die surface porosity affects yield granulator and die strength. Large aperture ratio,high yield of ring die pelletizing machine, low intensity; conversely, increase the diestrength, reduce the production of granulating machine. Because of the difference of ring die material and size, to get the ring die right hole opening rate, in order to better coordinate the production and life, there are great difficulties. For the die diameter is2~12mm ring die, the die hole opening ratio should be selected in 20% ~ 30%. The smaller the die hole, hole ratio value is smaller, conversely, the larger the aperture ratio. Factory according to the selected ring die material, die structure and size, thesuccessive approximation method, determine the ring die hole rate, ensure the ring die have sufficient strength, to prevent its rupture and shorten the service life ofbearing.

In the design of die structure, should minimize the ring    keywords:    feed pellet mill machine