With the development of the cutting tool industry, has introduced a carbide cutting tools, ceramic knives and cubic boron nitride cutting tools (CBN cutting tool), the following is based on a brief introduction of development order.
For high hardness of roll processing, first USES is carbide cutting tools, due to the roll roll hardness is generally above HRC45, especially some alloy cast iron/cast steel, hardness can reach more than HSD90 and hard alloy was processed.Is after the launch of the ceramic cutting tool, in all aspects of the ceramic cutting tool machining performance is higher than that of cemented carbide cutting tools, but the only drawback is the brittleness is big, and is part of the large roll casting, hard to avoid can appear casting defects (such as hard points, sand inclusion, porosity, etc.), the above problems is easy to collapse knife, processing and the result is bad.After cutting tool industry through constant research and development, developed the cubic boron nitride cutting tool, hardness higher than that of cemented carbide cutting tools and ceramic cutting tool, while the brittleness is big, but compared with ceramic cutting tool or a shock.But the machining high hardness of roll, the effect is not ideal.Developed after valin superhard non-metallic adhesive cubic boron nitride cutting tool BN - K1 grades and BN - S20 brand, compared with the conventional CBN cutting tools to increase the toughness, raise the efficiency of processing high hardness of roll.
Valin superhard non-metallic adhesive cubic boron nitride cutting tool BN - K1 type suitable for high hardness cast iron roll processing, non-metallic adhesive cubic boron nitride cutting tool BN - S20 brand suitable for high hardness steel casting/forging steel roll processing.Not only high hardness, good wear resistance, and solved the carbide cutting tools and ceramic cutting tool processing occurs when high hardness of roll cutting tool wear, or collapse problem.Meet the casting defect tool normal processing, there will be no severe wear or collapse phenomenon of blade.Here are valin superhard non-metallic adhesive cubic boron nitride cutting tool BN - K1 and BN - S20 brand of cutting parameter table.
Valin non-metallic adhesive cubic boron nitride cutting tool BN - K1 brand and BN - S20 brand of processing material and cutting parameter list
roll long hours lead to the failure, failure after roll how to repair?
Roll quality directly affects the working efficiency of the mill, rolling product quality and yield, roll consumption, etc.And roll consumption is an important part of the steel rolling process, in the process of rolling in the normal, damaged due to many reasons.Especially hot rolling roll more bad working environment.The main failure mode of the roll have crack, flaking and fracture (pictured), etc., including any kind of failure modes will affect the service life of roll.
At present, in general, iron and steel enterprise roll due to wear and tear when in need of repair, use turning or grinding way more fixed roller type.This way to improve the roll life significance is not big, just a kind of remedial measures.In general, the higher the hardness, wear resistance, the better.But the roll hardness and wear resistance increase at the same time, to cause a decline in toughness, concrete should be according to the requirements of the specific roll performance when using to determine the required hardness value.Adopt roll surface repair and strengthening heat treatment technology to improve the surface hardness of roll, reduce roll wear using amount, the so-called surfacing welding repair.By overlaying welding roller are mostly wear out and cannot use the old roll.Roll automatic submerged arc welding is a common method.
roll overlaying welding need to pay attention to?
(1) before using it in the surfacing welding defects or fatigue layer on the surface of the roll body, especially the crack must be thoroughly cleared;
(2) in welding, in order to prevent cracks, preheating, must first processing in.homogeneous preheating temperature according to roll and welding materials;
(3) the success or failure of the overlaying welding to key link, to obtain ideal welding layer must consider some variables, such as: welding voltage, welding speed, rotating speed of roll, roll temperature, welding current, welding material, etc., for some of high carbon and alloy elements roller core, to prevent the crack of fragile area, besides certain preheating measures, with low carbon low alloy transition layer for surfacing transition layer in advance.
(4) roll slow cooling after welding, cutting.In order to reduce the volume due to surface and internal cold speed range stress caused by the crack, to control the cooling speed.Finally, the roll after surfacing for turning processing, restore to the original size and finish.And performance of the roll after surfacing: 1) the service life of roll after surfacing in double or more;2) greatly reduces the cost of per ton steel, improve the production effect;3) after welding roller has good crack resistance, wear resistance, cold and hot fatigue resistance.
after surfacing how turning rolls back to the original size and finish?
After welding, the roll roll hardness is improved, and the roll is not neat, so leads to difficulties in turning, machining after welding roller can choose valin superhard cutting tool BN - K1 grades and BN - S20 brand, BN - K1 type is mainly used for high hardness cast iron roll, BN - S20 brand used in high hardness steel casting/forging steel roll, specific cutting parameters see valin superhard non-metallic adhesive cubic boron nitride cutting tool BN - K1 and BN - S20 brand of cutting parameter table (problem might form below).