New Technology In Mini Stone Crusher

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Mini Stone Crusher main frame

Mini Stone Crusher is a crusher widely used in water conservancy, building materials, chemical industry, etc. With the continuous development of Mini Stone Crusher technology, customers have higher and higher requirements for product quality and performance, and crusher manufacturers are constantly striving to meet At the request of the customer, the following is the research on the production process of the main frame of the Mini Stone Crusher by Shanghai Shibang Machinery.

The main frame is an important large casting of the Mini Stone Crusher, and its structure is complex, and the wall thickness is small and uniform. The structural characteristics of the frame determine that it is difficult to achieve sequential solidification and is prone to shrinkage. In the production, the deformation, shrinkage and shrinkage defects of the main frame are prominent, which not only affects the quality of the Mini Stone Crusher, increases the cost, but also affects the delivery time. This paper analyzes and optimizes the casting process of the main frame to ensure the sequential solidification of the main frame and the effect of the molten steel.

First, the process design

1. Analyze the experimental object

The experimental object selects the representative PE800 series Mini Stone Crusher main frame. The Mini Stone Crusher main frame has large contour size, complex structure and more uniform wall. The large contour size is 3727×2436 (mm), the weight is 35.31, and the material is J03006. .

2, the original process plan

(1) Determine the parting plan of the casting. The small wall thickness at the waistband and the large flange at the bottom are designed as parting surfaces.

(2) According to the order of solidification of the castings, the design is supplemented.

(3) Using a bottom-back casting system, the molten steel is led to the bottom of the casting through the sprue and the runner, and then injected into the cavity from the bottom by the ingate.

Second, the main frame casting process problems and analysis

Problem

According to the original process scheme, the shape and pouring were found, and a large amount of shrinkage appeared at the waistband, and the hardness of the casting at the intermediate shaft hole also failed to meet the technical requirements.

Cause Analysis

During the cooling of the casting from the pouring temperature to the room temperature, it undergoes three interrelated shrinking stages, namely liquid shrinkage, solidification shrinkage, solid shrinkage, and volume shrinkage between the liquid-solid phase lines is the main cause of shrinkage and shrinkage. stage. Large and concentrated holes are called shrinkage holes, and small and scattered holes are called shrinkage. When the liquid is filled through and the dendrites do not form a network structure (dendritic framework), the volume shrinkage appears as a concentrated shrinkage cavity and is located at the upper portion of the flowable unit of the casting: when the dendrites form a bamboo frame. The macroscopic feeding channel is blocked, and the volume of the liquid surrounded by the dendrite is shrinkage (in the range of dendrites).

Shanghai Shibang Machine Researchers proposed the concept of mass feeding and dendrite feeding by studying the flow state of molten metal in the solidification process. The results show that the shrinkage is caused by the flow of the molten metal, and the solidification and shrinkage of the alloy is not supplemented by the molten metal.

Insufficient liquid feeding is the root cause of the formation of shrinkage cavities. After the liquid feeding stops in other solidification processes, it enters the mass feeding and dendritic feeding. During the solidification process, the channels between the dendrites become tapered, if the pressure at the tip of the interdendritic channel is lower than the critical value of the formation of the shrinkage cavity. The interdendritic feeding has stopped. If the formed dendritic network structure is not very strong, and there is enough metal liquid pressure difference between the dendrites, the dendrite arm will suddenly break, so that the residual liquid suddenly flows into the isolation zone between the dendrites. This is “explosion filling”. In the solidification process of the actual casting, the main cause of shrinkage is the difficulty of mass feeding and dendritic feeding.

Process measures

The new process is mainly improved from the location where the shrinkage occurs, ensuring that the wedge-shaped feeding passage toward the riser is unblocked.

(1) The belt of the PE800 Mini Stone Crusher is too far away from the top riser, and the feeding gradient of the riser is not enough. Through the calculation of the modulus, the process subsidy is increased, the feeding channel is increased, and the feeding channel is later than the heat. The joints are solidified, and the castings are sequentially solidified. The improvement adds a process subsidy between the riser and the hot section, thus completely avoiding the occurrence of shrinkage.

(2) Increase the effective feeding distance of the riser. There are two ways to increase the feeder’s feeding distance, that is, increase the riser and place the cold iron. When the process is modified, cold iron is placed between the riser flanges of the upper and lower flanges, and the cold iron is placed at a small wall thickness to increase the end zone.

(3) Through the local heat treatment, the hardness of the casting at this place meets the technical requirements.

The process improvement solution can solve the shrinkage of the casting, which not only ensures the quality of the Mini Stone Crusher main frame, but also increases the production cost, delays the production time and delays the delivery time.

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