Patent

Common methods of deburring (1)

2019-05-16

Although the small thing of burr is not big, it directly affects the quality of the product. Therefore, with the emphasis on the removal of burrs in various industries, the method of deburring has also emerged endlessly. There are several common types of trimming/deburring:


manual


Traditional; the trimming knife gradually replaces these traditional methods, does not require technical processing, is cost effective and environmentally friendly.


Chemistry


Deburring is automatically and selectively performed on parts made of metal materials by the principle of electrochemical reaction. It can be widely used in the deburring of parts such as pneumatic, hydraulic, engineering machinery, nozzle oil pump, automobile, engine and other metal materials such as pump body, valve body, connecting rod and plunger needle valve. Suitable for internal burrs, heat treated and finished parts that are difficult to remove.


electrolysis


An electrolytic processing method for removing burrs of metal parts by electrolysis, referred to as ECD in English. Place the tool cathode (usually brass) in the vicinity of the burr of the workpiece, with a certain gap (usually 0.3 to 1 mm). The conductive portion of the tool cathode is aligned with the burr edge, and the other surfaces are covered with an insulating layer to concentrate the electrolysis on the burr portion. When processing, the tool is connected to the cathode of the DC power supply, and the workpiece is connected to the positive pole of the DC power supply. A low pressure electrolyte (usually sodium nitrate or sodium chlorate solution) with a pressure of 0.1 to 0.3 MPa flows between the workpiece and the cathode. When the DC power is turned on, the burr is dissolved and removed, and is carried away by the electrolyte. The electrolyte is corrosive, and the workpiece should be cleaned and rust-proofed after deburring. Electrolytic deburring is suitable for removing burrs of hidden parts or complex shaped parts in parts, and the production efficiency is high. The deburring time generally takes only a few seconds to several tens of seconds. This method is commonly used for deburring of gears, splines, connecting rods, valve bodies and crankshaft oil passage orifices, as well as rounding of sharp corners. The disadvantage is that the vicinity of the burr of the part is also subjected to electrolysis, and the surface will lose its original luster and even affect the dimensional accuracy.


Ultrasonic


Ultrasonic energy generated by ultrasonic waves acts on a liquid in a liquid that vibrates in a sparse state, tearing into small holes (ie, vacuum inside). These holes generate instantaneous pressures of up to several hundred atmospheres when they are broken. And this phenomenon is called cavitation. Ultrasonic deburring is the use of the impact force of hundreds of atmospheres generated by the "cavitation phenomenon" to remove the burrs attached to the parts. Ultrasonic deburring is not suitable for all burrs. It is mainly for microscopic burrs. Generally, if the burrs need to be observed with a microscope, they can be removed by ultrasonic method. For the burrs visible to the naked eye, mainly depends on the strength of the bond. The burrs with weak bond strength can use ultrasonic waves. Generally, burrs that can be processed with a knife can not be used by ultrasonic methods. The advantages and disadvantages of ultrasonic deburring.


High pressure water jet


As the name suggests, water is used as the medium, and its instantaneous impact force is used to remove the burrs and flashes generated after processing, and at the same time, the purpose of cleaning can be achieved. After many tests and tests, the final suitable pressure was found to be 30MPa-50MPa. If the pressure is insufficient, the deburring effect cannot be achieved. Although the pressure is too high, the burr can be removed, but there is a danger of damage to the workpiece. Usually, the hydraulic pressure of the hydraulic parts is within 20Mpa, and the burr residue that cannot be destroyed by the pressure of 50MPa is very small. The probability of falling off under the working pressure of several MPa is very small, and the root of the burr can also be considered. Residue is part of the workpiece. There are more and more manufacturers of high-pressure water deburring equipment, which can be summarized into two categories: workpiece moving type and nozzle moving type. The workpiece moving type is low in cost and suitable for deburring and cleaning of simple valve body. The disadvantage is that the matching degree between the nozzle and the valve body is not ideal, and the burr removal effect of the cross hole and the inclined hole inside the valve body is not good; the nozzle movement type is controlled by CNC. The distance between the nozzle and the burr of the valve body can be effectively adjusted, which effectively corresponds to the cross hole and the inclined hole inside the valve body and the burr of the blind hole. However, due to the high cost of the device, only the heart part of the automobile and the hydraulic control system of the construction machine In order to enjoy this favor.


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