Mining machinery and equipment Casting Process

Mining machinery and equipment Casting,cast manganese steel castings,steel castings Casting

With the rapid development of social economy , the global mining economy has also made considerable progress. For iron ore, copper ore and other metal ores surge in demand , driven by the market for mining machinery and equipment castings demand, which greatly increases the casting process for casting requirements . And mining machinery often used during casting the casting material is carbon or steel, when the casting material during the casting , the biggest problem is to note casting wear , so want to improve the cast process , the first casting wear resistance has been improved.

1 kind of mining machinery and equipment wear castings
With China's economic development , China has made in wear-resistant castings foundry machinery and equipment aspects of the rapid development , some of which , such as balls , liners and other wear-resistant castings and even exported overseas , the technical level has reached the international advanced level. Mining machinery wear-resistant castings There are many kinds , the most important are what several categories.

1.1 austenitic manganese steel wear-resistant
In austenitic manganese mining equipment in a very wide range of applications , it has a high toughness , ease of processing and hardening and high strength and good wear resistance . In applications such as casting cone crusher and broken walls , gyratory crusher liner , hammer crusher hammer mill liner and wet mine will widely used austenitic manganese steel . Mn13 series is the most important wear-resistant manganese steel materials , and in some technologies developed countries generally use a higher strength and wear resistance and better wear resistance of austenitic manganese steel Mn13Cr2 . Technological advances in the development of manganese content depends on Si and P , where P levels even require at <0.04% , in the process of casting the main problem is how to reduce the impact toughness without the premise of improving resistance to manganese grindability .

1.2 wear-resistant white cast iron
In the wear-resistant castings , the mainstream is cast iron chromium white iron, is the most widely applied at home and abroad . Cr15, Cr26 type wear high chromium white cast iron is cast iron , is now the best quality and most technologically sophisticated one. With the continuous development of technology, silicon chromium cast iron and low chromium cast iron has also been the development and production of its superior wear resistance of high chromium cast iron , the future market prospects better . In the future development with balls , for example, need to meet abrasion , cracking , deformation , and many other casting process requirements, to move energy-saving , environmental protection, high-quality, high wear resistance direction. Casting also been large-scale industrialization and automation.

1.3 Non- manganese alloy wear-resistant
With the continuous improvement of mining technology requirements , non- alloy steel, wear-resistant manganese has been the development and promotion applications. Mainly used in mining machinery and equipment in a wet ball mill liners . This is a low carbon high alloy steel liner, ideally suited for wet ball mill . Meng Department of Central Africa in the application of the test of life is twice as resistant alloy steel high manganese steel liner , so that the effect of greatly enhance the efficiency of the mill and description , the future will continue to expand and promote the application . In the next upgrade process , the need to constantly improve the casting process and alloy steel heat treatment process optimization. Technology advances , high strength, high wear resistance of carbon resistant alloy has achieved rapid development , 50 HRC hardness alloy steel , αkn reached 200 J / c ㎡ ; hardness of 55 HRC steel alloy , αkn reached 100 J / c ㎡ , making not only wear resistant alloy steel has been a huge increase hardness and toughness have also been strengthened.

2 . Improve the wear resistance of mining machinery in manganese steel castings Casting
In the cast mining equipment , the use of manganese has been quite extensive, due to the strength of mining machinery and equipment requirements for high performance in terms of equipment is casting machinery and equipment wear , so how to improve the wear resistance manganese sex , analyze how to strengthen casting process mining machinery and equipment .

2.1 improve the density of the cast manganese steel castings
Greatly affect the degree of densification to wear manganese steel castings , so during casting , technological aspects of what should be done to consider several aspects , first , for more than forty mm wall thickness manganese steel castings , must be strictly accordance with the norms using cut sheet feeder is easy to achieve the purpose of feeding , so with the use of outside cold iron , manganese can greatly enhance the density, the wall thickness of less than forty millimeters manganese steel castings , using the simultaneous solidification technology, this time also need to meet outside the cold iron . This one may consider using heat riser , which can improve the manganese steel castings riser yield, ensure wear resistance manganese . Second, in batches , and the shape is relatively simple when casting casting technology to make use of the metal type hanging sand process , so you can in the shortest time to complete the wear resistance manganese steel casting for maximum efficiency . Third, when casting the casting process , the need for strict compliance with the "three low operating " mainly refers to the three low- casting mold with cold , cold casting, the low temperature steel. This is to ensure that the key and foundation wear resistance manganese steel castings .
Strengthening heat treatment process manganese

2.2 Casting
The main purpose of manganese is subjected to heat treatment , the heat treatment to achieve a single austenitic manganese , manganese enhance its hardness and toughness , to the use of a standard casting . Manganese steel castings with respect to the general , the thermal performance is poor , only about about one third of carbon . Therefore, the heat treatment process requires a higher than normal carbon steel , more strict. Taking into account the heat treatment , the manganese may appear deformed or cracking quality problems , lining when the device requires the use of vertical loading , preheating and manganese , lead manganese heating or cooling to prevent deformation cracking.

First, the manganese steel casting a thick , slowly heated to 650 ℃, and pretreatment 3 hours , this time can be part of the austenite has been decomposed , the decomposition amount up to more than half. This will cause the decomposition process and the presence of iron carbide , the formation of austenite grain refinement, grain is small within the range of permitted . Secondly, after preheating , heated to 1100 ℃, holding about 6 hours . This process needs to be careful not to make the casting temperature leads to decarbonization, it 's time to decide on the insulation wall thickness of manganese , calculated according to 25mm / h, to ensure that the organization is dissolved carbides . Again, preheating and heating through two processes , the need for water cooling rapidly conduct water toughening treatment . Manganese in the water toughening process , into the water temperature is about 1000 ° C , into the water through the three or more swinging , the circulating cooling water is injected into the process , to prevent the water temperature is too high . Finally , water toughening treatment to maintain 8 hours 450 ℃. After 'll get austenite , which would form a high strength steels fierce , increasing yield strength manganese steel , thereby enhancing the overall wear resistance of manganese . Which should be noted that the temperature of the water tough to grasp and control must be precise place. Temperature higher than 450 ℃, carbide becomes thick, forming needle-like , this distribution reduces the toughness manganese can not achieve good wear resistance.

3 Summary:
In the mining machinery equipment Casting process, respect the need to enhance and strengthen There are a lot of them wear is an important part of the article by casting wear mine introduced classification proposed in the cast manganese steel castings by improving manganese density and strengthen the heat treatment process to enhance wear resistance manganese steel , in fact, there are many other transformation process , such as improving grain size manganese steel , manganese steel surface decarburization treatment , can improve the manganese wear resistance.