What are the forms of sensor failure?

April 28, 2020

(1) The causes of effective ring burn or burn are:


1) No water is connected to the effective ring.For example: the cooling water pump suddenly stops running;When debugging induction heating process, there is no cooling water.


2) Connect the cooling water pipe in and out by mistake.For the multi-turn inner hole heating sensor, the inlet water must be connected to the conducting tube returning from the center.


3) The sensor has been subjected to excessive power. For example, there is a semi-axial scanning sensor, which can quench the qualified product with normal process of 50kW. In order to increase the output, a factory increases the power to above 150kW, and fails to take measures to increase the water flow, resulting in effective ring burning.


4) The sensor USES hard water for a long time, resulting in burning off due to the reduction of the flow rate due to scale, which is commonly seen in high-frequency sensors.


5) For the effective ring with very large current carrying density (such as 1200A/mm and above), high-pressure water (0.6~ 1.0mpa or higher) must be used, and the soft water cannot dissolve into air, bubbles will make the local temperature of copper tube rise too high and burn or oxidize.It is a necessary measure to prevent cooling water from entering the air by closed circulation and connecting the inductor return pipe under the water tank level.


(2) The contact surface burns between the contact plate of the inductor and the contact plate of the secondary winding of the quenching transformer, between the contact plate of the inductor and the quick change chuck, there is a large current through the work, so there are three requirements for this contact surface: (1) the contact surface is clean;The laminating area should be more than 60%;(3) there is a certain pressure, that is, the pressure bolt in the work of heat will loosen the buckle, must be regularly checked and re-tightened, this point is very important.Otherwise, with the extension of the use time, the contact surface will be oxidized, resulting in the increase of contact resistance, a fever and more severe oxidation of the vicious cycle, ultimately resulting in contact surface ignition and burns.If the v-shaped contact surface of the crankshaft sensor is biased or not pressed tightly, this contact surface will burn, bad contact, and even affect the sensor power, this point must be paid attention to.


(3) Effective ring copper thermal fatigue cracking load current density of the effective ring, in the moment of power, copper rose to a few hundred degrees of high temperature, when the power immediately cooling water, copper parts of the continuous thermal expansion and cold shrinkage, after tens of thousands of times more than the cycle, will produce thermal fatigue and bubble and crack phenomenon.Crankshaft effective ring is a typical example, in the effective ring inserted in the middle of the magnetic body, closure density is the largest, easy to bubble, the section of the magnetic body is divided into two parts, with gaps in the middle, the middle is not easy to bubble.


(4) Effective ring and the workpiece meet burn this is related to the gap size or bending deformation of the workpiece, now in addition to spraying ceramic and other measures can solve this problem, for a kind of experience is the workpiece and machine tool lined with insulation sleeve, so that the workpiece is not grounding.


(5) Other reasons and electrical ヽ machine equipment failure, hose off and take over when the tape falling into the inlet pipe, etc.