Carbide blade and steel (arbor) thermal expansion coefficient of a large difference, and the thermal conductivity of the alloy is also worse than the blade material, if the welding process is improper, will cause the Weld or stress is too large, in the course of the blade will appear Shedding or cracking phenomenon, a serious occurrence of welding or welding after the blade directly crack, affecting the life of the tool. Therefore, Carbide Inserts the welding process is critical to the life of the blade. Carbide blade welding the most commonly used are high-frequency welding and oxygen welding two processes. High-frequency welding because the temperature is easy to control, heating uniformity, high efficiency, welding quality stability has gradually become the blade of the main welding methods.
1. Carbide blade inspection
Before welding, please check whether the carbide blade is carburized, cracked, curved or uneven uneven. Brazing surface must be flat, Carbide Inserts if it is spherical or rectangular carbide brazing surface should also meet a certain geometric shape, to ensure that the alloy and the matrix between the good contact in order to ensure the quality of brazing. Seepage serious (darker color, shiny shiny) of the blade, Carbide Inserts there will be solder or welding on the phenomenon.
Carbide blade surfaces should be kept clean, free of oxide and oil. Generally the surface of the blade sandblasting, no sandblasting equipment, the case can be hand holding carbide, in the rotating green silicon carbide grinding wheel on the brazing surface of the oxide layer and black letters. If you do not remove the hardened alloy brazing surface oxide layer, solder is not easy to wet carbide. Experience has shown that the brazing surface if the oxide layer or black grades letters, should be sandblasted, otherwise the solder is not easy to wet carbide, brazing seam will still appear obvious black letters, so that the brazing area decreased Desoldering phenomenon. Sandblasted carbide can be cleaned with gasoline and alcohol to remove oil.
Arbor material generally use carbon content of 0.4 ~ 0.7% of the carbon structural steel, Carbide Inserts handle height and blade thickness ratio should not be less than 3: 1.
3. Blade slot
The shape of the groove and the blade is as uniform as that of the blade, and the contact surface of the blade and the sipe is flat and the depth of the insert groove is less than 0.3 ~ 1mm. The shape of the sip and the welding rod is inconsistent or a large difference between the formation of closed or semi-enclosed groove, easy to cause too much welding surface and the welding layer is too large, Carbide Inserts due to thermal expansion after the shrinkage is inconsistent, Caused by stress is too large, the formation of crack. To meet the required use of the weld strength requirements, as far as possible to reduce the area of the brazing surface. The saddle should also be sandblasted and cleaned to remove oil. Cleaning large, you can use alkaline solution to boil 10 ~ 15min.
Carbide blade and steel oxygen - acetylene brazing operation of the technical points are as follows:
1. In order to prevent the carbide blade in the brazing process decarbonization or over burning, to use carbonized flame.
2. Brazing temperature of about 1000 ℃ is appropriate, that is, Carbide Inserts carbide blade heating was bright red. If the blade is dark red or white light can not braze, because the former temperature is too low, the latter temperature is too high, there have been burning phenomenon.
3. Torch from left to right, from right to left, from top to bottom on the knife body for repeated heating, so that the blade and the blade heat uniform.
4. The distance between the tip and the arbor when brazing is about 50mm, and the tip angle of the tip and the tip is 110o, which ensures the effective use of flame heat and heat balance. During the brazing process, make the flame always cover the entire brazing area, Carbide Inserts so that it is isolated from the air to prevent oxidation or produce pores.
5. The brazing speed should be determined by the size of the blade. Brazing 40 steel and YT15 carbide cutting tools should be completed in 1min, this can effectively prevent the carbide over burning or decarburization.
6. After brazing, use the flame to heat the blade, and then slowly leave the nozzle, so that the welding slowly cooling to prevent cracks.