Excavator cast iron

Li Wai-Pan Pan Heavy Duty Casting Over Shandong Yishui Machine Tool Factory 276400 Zhang Hexiang Shandong Linyi Mechanical and Technical Workers School 276003 Yu Hongyi Parts Features The weight of the iron produced by our factory is muscle 100. Its structure is bread-like and its top is composed of many arcs. Surface composition, the bottom surface and the cavity surface is the mounting surface, the physical position tolerance requirements, and the rest of the surface is non-processing surface. The part has the following characteristics, the part's external dimensions and weight weigh up to 61., the casting wall thickness changes greatly, the thickest place Up to 455, and thin parts only 3 parts processing surface, casting requirements, in particular, the appearance of higher quality requirements, several pre-placed screw holes also require a higher position accuracy. Parts are complex in shape, but the casting process is better, and it can be directly from the mold, without the need for core boxes.

Modified cavity brush coated graphite powder. With the dry sand type of clay, the hardness of the sand type must reach 90 to prevent deformation of the casting caused by the graphitized expansion.

Since the shape of the casting has a good craftsmanship, it can be used directly from the sand box. As the weight of iron, its appearance quality is an important technical indicator. For this reason, the part profile arc faces down, and the entire part is cast in the bottom box, so that the part will not be misaligned on the parting surface. Due to the fact that the parts are relatively difficult to mold, and lack of a suitable position for the striking pattern, the entire pattern is divided into two parts. 1 Double-dotted line is used as the parting surface. The upper and lower molds are positioned by positioning pins and connected by bolts, which can be divided.

The modeling process is as follows. 2 The bottom of the upper mold 4 is laid flat downwards, the lower box 1 is snapped on the pattern, and the upper and lower molding common bolts 2 are suspended on the lower box belt, and then the sand is filled and solidified from the bottom surface of the lower box. After tamping, turn the lower box 180, loosen the bolt 2 and then hit the mold to make the pattern and the sand type properly separated. The upper box is lifted and the upper mold 4 is also lifted from the upper box. , Flip the upper box 180, loosen the bolt 6, hit the parting surface, and then lift the upper mold 4 to separate from the upper box. , Hit the lower die 3 in the box and lift the die. , Refining the cavity. Carefully flatten the surface irregularities that may occur on the parting surface of the lower box, and at the same time provide the quality of the casting surface. 1. Lower box 26. Bolt 3. Lower mold 4. Upper mold 5 upper box 7. Nut 8. Positioning shaft 9. Pre-embedded iron pouring and other parts due to the weight of the parts exceeds the existing tonnage of cupola and molten iron ladle capacity, so use two 3.51 iron liquid package, pouring from both ends. That is, the cupola melts out the first iron liquid and then performs the heat preservation treatment. After the first iron liquid is melted out, the molten iron is poured from the first sprue, respectively. 3. The step pouring system is used, and the upper layer is located on the parting surface with two layers for each layer. In the runner, when the cross section is 25150, the slow cooling and slow pouring is adopted, and the casting temperature of the molten iron is appropriately reduced to 1350 to fully exert the expansion and contraction effect of graphite.

According to the weight and size of the weight of the weighted iron, it is determined that 6 feeding risers are to be used, of which 4 are the pressure-side feeding risers, which are respectively located on the 4th and 0th points of 3, and communicate with the inner runner. The edge section is 2,30, so that it can be kept when the cast iron type sand coated cast iron cast iron gear production practice Xuzhou Petroleum Machinery Factory Jiangsu 221008 Zhang Fan Xu Jiaxuan Li Dongjun Li Taohe pumping unit series gear reducer of ductile iron gear, made of QT7a2, rough weight 5,501,650 kg, main section thickness 6090 stomach. In order to ensure the cooling rate of the rim, it can prevent the occurrence of various defects such as spheroidizing, declining graphite distortion, and coarse eutectic groups, and the graphitized expansion of the ductile iron, which makes the parts of the casting compact and prevents the hot spots from being formed due to insufficient feeding. The shrinkage porosity is reduced, and the effect of the pouring riser on the cooling of the casting is reduced. Nowadays, the production plant generally adopts the system of external cold-iron and rain-flooding risers around the rim to produce sand molds using dry-type clay sand rain pouring cups with resin sand.

1. Rain pouring riser 2. Air outlet riser 3. Cold iron But the above process has the following drawbacks: The cold iron surface is easily oxidized, resulting in sticking with parts, or forming pores in the casting.

Cold iron is used 5,7 times after it has been used for a certain number of times. Since the oxidation must be replaced, the consumption of cold iron is large.

The molten iron is in direct contact with the cold iron, and the molten iron in the layer is rapidly cooled. A surface quenching layer which is easy to form a hardness is required to be processed by graphitizing annealing.

When the compactness is not uniform, the graphitic expansion of the castings will cause the cavity to swell, and the part of the expansion force will be lost. As a result, casting bulging phenomenon will occur, and the shrinkage tends to increase.

For this reason, we designed an iron-type coating for the disadvantages of the above process. 1. Iron-based sand-casting process design Iron-clad sand-casting is a kind of casting process in which a metal-type iron-type cavity is covered with a thin layer of sand to form a mold. . The metal type itself acts as an indirect cold iron, achieving the self-compacting effect of saving a large amount of cold iron, avoiding the bulging phenomenon of the casting and preventing shrinkage and contraction; the sand coating is between the cold iron and the iron liquid The venting and buffering function prevents the surface pores of the casting and reduces the iron-based iron solution that can fundamentally solve the original process.

Iron type sand coating According to the structure of the gear, we use the box shape, because the middle box mold to withstand the graphitization expansion force is very large and need to strengthen the cooling, so the use of iron type sand coating. The top and bottom types still use dry clay sand 2 for economical and practical purposes.

Iron thickness, especially the thickness of the sand coating, will have a decisive influence on the solidification rate of the casting. According to the empirical analogy, the iron-based heat storage capacity should not be lower than the direct cold iron in the original process, taking into account the good heat dissipation capacity of the iron type, take the iron thickness as the thickness of the rim 0.8. The selection principle of the sand cover thickness It is on the basis of achieving the purpose of direct roughing, and turning down the sand process on page 15.

The temperature is relatively high to facilitate feeding, and it is also easy to remove the riser after casting.

The installation of the embedded iron at the screw hole adopts the live block shape, that is, the positioning hole is first made on the sand block of the embedded iron coaxial line with the live block. The embedded iron 9 and the positioning shaft 8 are screwed together, and the positioning shaft is inserted into the sand-type positioning hole, and is fastened to the lower box with the nut 7. After the casting, the positioning shaft is unscrewed from the casting to be reused for the next time.

After the implementation of the above-mentioned process methods, the casting of the weighted iron can be relatively smoothly achieved. At the same time, it is also necessary to pay attention to the following points. The sand-type crucible should be fixed to the required hardness, and the tamping should be uniform.

Use temperature-resistant surface sand and paint to prevent surface sintering.

Sand drying should be slow-baked at low temperatures to prevent cracking of the sand-type skin.

Since the weighted iron material is mostly low grade gray cast iron, it is necessary to pay attention to the expansion stress caused by precipitation of graphite during solidification.

The wall thickness and weight of the castings are large and should be opened after casting 24 to prevent cold cracking of the castings. 2521

Geo-membrane is produced by a method of three layer co-extrusion model.  The raw material is processed at 200°C by fusing and coextrusion, whose basic properties are kept during the producing process. 

Features: 

1)  Can bear chemical erosion. 
2)  A wider using temperature range and a longer using life. 

Application: 

It can be widely used in areas of garbage burying,  waste disposal,  tail minerals storage and underground construction projects.  

Hdpe Geomembrane

High Density Polyethylene Geomembrane, Hdpe Geomembrane Smooth And Textured, Hdpe Geomembrane Polyethylene

Feicheng Lianyi Engineering Plastics Co., Ltd , https://www.lianyigeosynthetics.com