Batching → melting → crushing → milling → pressing → sintering and tempering → magnetic testing → machining → surface treatment → finished product

 

   Main equipment: melting furnace, crushing unit, jet mill, forming press, vacuum packaging machine, isostatic press, sintering furnace, magnetic performance tester, coreless grinder, surface grinder, slicer, wire cutting machine, lathe, drilling machine , Profiled grinder, table magnetometer, flux meter, etc.

 

 

   1, neodymium iron boron ingredients: according to various product requirements, using different formulas, accurate measurement of various materials, of which pure iron needs to remove the oxide layer.

 

   2. Neodymium-iron-boron smelting: According to different requirements, there are ordinary melting furnaces and quick-setting smelting belt melting furnaces. Melting furnace: In the high-vacuum furnace chamber, using an intermediate frequency 2500Hz power supply, relying on electromagnetic induction, the material is heated to about 1650 ° C, so that the material is completely melted and fully mixed. Rapid casting in a corresponding ingot mold with rapid water cooling. After a certain period of time, it is completely cooled to 50 ° C. It is released from the furnace when it is rapidly cooled. The working principle is the same as that of ordinary melting furnaces. The difference is in the casting method. Slowly poured on high-speed rotating water-cooled copper rolls, under the action of centrifugal force, to form a thin sheet of 0.3-0.5, and leave the oven when the material is cooled to 50 ° C. There should be no oxidation on the surface of the baked product.

 

   3. Neodymium iron boron crushing: specifically divided into mechanical crushing and hydrogen furnace crushing. First use a jaw crusher to break a large steel ingot into small pieces, and then use a medium crusher to crush into a powder of 0.5mm3 size under the protection of nitrogen. The powder is shipped in a vacuumed, nitrogen-filled protective barrel for the next flour milling process. If it is a strip, it can directly enter the crusher. The hydrogen-broken product can directly enter the next milling process.

 

   4. Neodymium-iron-boron powder: Use a jet mill to crush powder in the crusher barrel (0.5mm3), use nitrogen as the medium, and use multi-gun spraying to crush larger particles according to the principle of particle collision. Then, the powder with a certain particle size is sorted by a sorting wheel with a certain rotation speed, and the powder with a certain particle size is 3-6 μm, and then the gas-solid separation is performed by a cyclone separator to enter a powder container. After the powder mixing unit performs the mixing process, it can enter the next step of forming.

  

   5. Neodymium-iron-boron compacting: The process of putting the powder into the mold and making it into the required shape with a hydraulic press under a certain external magnetic field. The powder in the nitrogen-filled protective powder container is weighed by a single mode of the powder manually or automatically in a nitrogen-exhausting space. Take a powder box under a bag or nitrogen protection, put it into the mold cavity of the forming mold, and perform orientation, pressing under the action of a strong magnetic field, and then demagnetize by the corresponding reverse magnetic field to remove the block and quickly vacuum-pack it. Vacuum packaging generally has two layers. The first layer is manually packaged with a polyethylene film of about 0.03mm to protect the corners of the block. Put into a relatively thick second layer of about 0.08mm polyethylene film bag. Put it into the vacuum packaging machine, and perform the extraction, exhaust, heat sealing, and reclaiming process. The relative density of the blocks pressed in the above process is relatively small and the density distribution is not uniform. In order to increase the density of the blocks and improve the uniformity of the density distribution, a secondary press using an isostatic press is required. Put the well-packed block into the isostatic press chamber and seal it. Use hydraulic oil or water as the medium, pressurize it to about 20MP, keep it for a certain time (3-8 seconds), release the pressure and take it, and place it in the oil filter table on. Strip and pack according to the instructions of the team. Put the intact block into the sintering box, put it into a revolving container with the function of suction and nitrogen filling, prepare to load the furnace, and enter the next process.

 

   6. Sintering of neodymium iron boron (tempering): In high vacuum space, high temperature is applied to the product, so that the solid particles inside the product are bonded to each other, and the crystal voids (pores) and grain boundaries are gradually reduced. Its total volume shrinks, its density increases, and finally it becomes a dense polycrystalline sintered body with a certain microstructure. Place the material box containing the material block on the movable furnace rack of the vacuum sintering furnace, arrange it neatly, cover it, push it into the melting chamber, close the furnace door, and gradually start the vacuum unit. When the vacuum rises to a certain value (5 * 10 -2Pa), start the heating and sintering program to complete the entire sintering process. After the completion, fill with argon, start the fan, and quickly cool to 70 ° C, and then vacuum 5 * 10-2Pa, start the heating and tempering program. After completion, fill with argon, quickly cool to 70 ° C, and perform the second aging. After the entire process is completed, when it is cooled to 50 ° C, the gas is deflated, the door is opened, and the oven is taken out, and the inspection staff takes samples. After passing the test, it can be put into the warehouse for use. So far the entire blank production process is complete. The finished product production process can be carried out according to the needs of the order. The tempering procedure is a process of stabilizing and increasing the coercive force of the internal organ.