Copper Wire drawing machine continuous annealing process; In order to improve product quality and production capacity and reduce energy consumption, the cable industry is gradually replacing the original tank annealing with continuous annealing. The working principle of copper wire drawing machine continuous annealing is to use a certain length of copper wire to directly short-circuit the copper wheels of the two positive and negative electrodes.
Because the resistance of the copper wire is quite low, it can also generate a large short-circuit current under low voltage conditions. Using this low voltage and high current can achieve the purpose of burning the copper wire soft. In the field operation, some phenomena such as thinning of the wire diameter after annealing, scratches on the surface, redness of the copper wire, discoloration of the copper wire, and oxidation of the copper wire will be caused. Now according to the phenomenon, combined with the principle of annealing to explain and solve some mistakes in operation.
- The wire diameter becomes thinner after annealing: when the copper wire is in a hard state, the exit die is the sizing die, and the tension is not large enough to draw the wire diameter.
However, during continuous annealing, the heat of the copper wire makes the wire material soft, and the wire itself has a certain extension. In order to send out the extended part of the wire in time, so as not to rub the conductive nickel ring of the copper wheel into a groove, the annealing is generally combined with foreign advanced experience to make a triangular annealing structure. The outer conductive copper wheel of the triangular structure is divided into inner and outer grooves, and the copper wire is introduced through the inner groove to complete annealing. Lead out from the outer ditch to reach the take-up line.
In order not to make the nickel ring groove, the diameter of the outer groove is larger than that of the inner groove, which structurally solves the problem of the nickel ring groove.
In order to compensate for the problem of thinning wire diameter during annealing. Generally, it is more appropriate to choose the continuous annealing outlet die to be 0.0015-0.0035 larger than the actual required wire diameter. The extra part is just naturally extended.
Because the wire after annealing is already very soft, appropriate tension weight should be used for different wire diameters. If the wire diameter is small and the tension is high, the wire diameter will be thinned. The adjustment of tension is quite demanding in terms of annealing. You cannot use one tension for any thread.
- Surface scratches: Continuous annealing is to use copper wires to continuously contact and lead out on the conductive wheel to complete the short circuit between the positive and negative electrodes and achieve the purpose of annealing.
Theoretically speaking, if there is relative movement between the copper wire and the copper wheel, certain scratches will be produced, and the wire is also a process of continuous electric shock on the copper wheel. The thin line is not very obvious because of the small contact area, and the thick line is much more obvious because of the large contact area. In order to reduce the scratches caused by friction and electric shock between the wire and the conductive wheel, the cooling water must have a certain lubricating effect (it is recommended to use stewing oil, add it at a concentration of 0.1% or directly use drawing oil with a certain antioxidant function, Added at a concentration of 1-3%) to reduce the friction between the wire and the conductive wheel. The second is to increase the tension as much as possible without pulling the copper wire thin, so that the slip between the wire and the conductive wheel can be reduced, and the scratches can be minimized. The third is to check whether there are any damaged and rough places in the guide wheels and porcelain holes. The fourth is to solve the problem of difficult adjustment of the transmission between the main engine and the annealing machine as soon as possible. (The annealing part is controlled by a separate motor, and a tension frame is installed at the end of the annealing line. The annealing part independently forms a PID closed-loop control, which solves the slippage caused by the different wire diameters of the main machine and the annealing part, and solves the slip between the main machine and the annealing part. Poor, so that the electric shock point caused by the slip between the copper wire and the nickel strip is reduced to the minimum.
- Redness of copper wire after annealing: continuous annealing is divided into three sections: preheating section, working section, and cooling section. Because the length of the wire in the preheating section is relatively long, the temperature will not exceed 250 degrees, which will not discolor the copper wire.
The current in the working section is large, and the temperature of the copper wire is high (about 550 degrees). If there is air in the working section, copper and oxygen will produce copper oxide under heating conditions. This section is most prone to oxidation and redness. The working section is generally protected by steam (or water). If the steam is not enough (or the water level is too low), it will be red in this section. The first solution is to increase the amount of steam (or raise the water level). The second is to increase the water level of the lower copper wheel to ensure that there is no air in the working section.
Note: In the case of using steam protection, the cooling water level cannot be higher than the steam outlet, otherwise the steam will directly heat the circulating cooling water, which will absorb a large amount of steam and cause the steam pressure to be zero (the heating lamp of the steam generator shows that it is always heating, But the steam is zero pressure. Many times it will give people the false impression that the heating tube of the steam generator is burned or the power of the steam generator is not enough. Pay attention to this phenomenon in the production process to avoid being misled. If there is no steam protection in the working section, the copper wire The color will change when it comes out. The solution is to properly reduce the cooling water inlet pressure. It should not be too large. At the same time, ensure that the water outlet at the return port has a certain pressure, and air cannot come in from the return port.
- Discoloration of copper wire (dark red or whitish): Continuous annealing will soften the wire in the working section, and it must be cooled in the cooling section to ensure that the lead-out wire is not hot or water-free.
In order to solve the problem of insufficient cooling after continuous annealing of large-scale wires, the lead-out wires are too hot, resulting in dark red or white copper wires, there are two water inlets in the cooling section: water inlet under cooling and water inlet during cooling. When making small gauge wires, just turn on the water inlet after cooling down. If you make a large gauge wire, both water outlets must be opened, so as to enhance the cooling effect of the copper wire. The lead-out wire will not be too hot, and it is not easy to produce dark red or white. Insufficient cooling of continuous annealing generally occurs on copper wires with relatively large annealing specifications, because steam was used to protect annealing in the past, and the working section and cooling section are connected, so the water level in the cooling section cannot be higher than the steam inlet position, otherwise the water will Just block the steam port, but the water level in the cooling section is not high, and it cannot have a good cooling effect. It’s a very contradictory thing. In order to solve such a difficult problem, we improved the annealing design, which fundamentally resolved such a contradiction. According to the different wire diameters, adjust the water level of the cooling section at will. To achieve the purpose of cooling.
- Copper wire discoloration: There are two situations, one is that the copper wire changes color after annealing, and the other is that the copper wire is good at the time of annealing, but it will oxidize and change color after being stored for a long time.
For the former situation, it is mainly to pay attention to whether there is air in the working section, and the solution is the same as above. In addition, if the cooling water is too dirty or the water quality deteriorates, it needs to be replaced with clean cooling water. The second situation is generally caused by water, mainly to solve the problem of drying. If the air is not dry, consider installing a wiper mold to solve it, and the effect is also very good. Letting the copper wire come out without water is the ultimate solution.
- Precautions
Because of the continuous annealing of the drawing ribbon, there are many things to pay attention to in operation. If you don’t pay attention to one link, you will have trouble in production. The above is just an introduction to the typical failure cases on-site.
In actual production, in order to solve hidden dangers at the source, some points should be paid attention to in the peripheral configuration of equipment:
1: The volume of the drawing oil pool for the center pull should not be less than 7 cubic meters per unit, and the cooling oil pool for the center pull should not be less than 3 cubic meters per unit. The oil pool should be as long and wide as possible, and not too deep, which is conducive to heat dissipation.
2: All the heat generated by the copper wire during the annealing process is taken away by the cooling water so that the cooling water will be heated continuously. When the temperature of the cooling water exceeds 70 degrees, the cooling effect is not ideal, and the copper wire will turn red. Therefore, the cooling water pool should not be too small, and the amount of cooling water must be sufficient. It is recommended that the cooling pump motor use a self-priming pump with a three-phase 0.75KW or more and a water outlet diameter of 1 inch. Single-phase pumps are not recommended. When the pipeline is laid, there are as few elbows as possible to ensure the water flow and pressure.
3: The mold of the high-speed wire drawing machine should match the area reduction rate of the equipment. It is better to start the machine if it is too large, but the life of the tower wheel will be shortened. If the matching is too small, it will be difficult to draw the thread, and the thread will be easily broken when the speed is fast, but because of the small slip, the cone wheel is not easy to groove. According to on-site experience, it is enough to add 2-3 sliding coefficients on the basis of the area reduction rate of the equipment in the general mold ratio. The high-speed wire drawing die requires that the sizing area is shorter than that of the soil wire drawing machine, and the bell mouth should be round. The longer the sizing area, the longer the life of the mold, but the longer the compression area, the corresponding line speed cannot be added, and the high speed is especially easy to break. For the wire drawing machine, polycrystalline is usually used for the bridge die, and diamond is used for the export die because it is a sizing die. It is best to use diamonds in the last three or four molds close to the exit mold. There are also many domestic molds with stable quality. Tianchang’s and Hebei’s molds can also be used, the price is relatively low, and the cost performance is very high.
4: The quality problem of copper material is the most difficult fault to check. Generally, it is often inexplicably disconnected, and the large and small specifications are similar, which brings the biggest headache to the front-line workers. And still can’t find the reason. Only after replacing several batches of busbars can the experience be summed up. Our manufacturers are helpless.
5: The problem of the threading method, in order to reduce the thread sliding coefficient on the tower wheel, try to make as many circles on the tower wheel as possible. Generally, the circle on the tower wheel should not be less than 4 circles. If there are fewer circles, the tower wheel will be easier to groove . It is not good to have too many circles, and it is easy to press the lines on each other.
6: The problem of tension air pressure adjustment, under normal circumstances, the greater the tension air pressure when not annealing, the better, as long as it is not so large that it will break the thread. Because of the double frequency conversion control, the speed of the winding frequency conversion mainly depends on the precision potentiometer behind the tension rod to divide the intermediate voltage to obtain the balance of the winding and unwinding. If the tension air pressure does not reach the air pressure value required by the wire diameter specification, it will cause winding. The speed is slow, the slip difference becomes larger, and when some customers report that they do not anneal, the copper wire will burn red after the machine speed reaches 1300M/MIN. The friction of the copper wire on the fixed wheel of the main engine generates a lot of heat, which anneals the copper wire. When such a situation occurs, the fixed speed wheel of the customer’s main engine will be grooved (the fixed speed wheel of the general wire drawing machine will not be grooved). During continuous annealing, attention should be paid to the tension and air pressure, and it should not be too large, otherwise the wire will be thinned a lot, resulting in serious bunching. The adjustment is adjusted on-site according to different wire diameters. The manufacturers of copper materials are different, and the corresponding annealing pressure is also different. It is best to find out the empirical data for fixing copper materials on site. Theoretical data is not reliable. Sometimes in continuous annealing manufacturers, annealing is required and no annealing is required. On-site workers adjust the tension and air pressure during annealing, but if they do not increase it in time when annealing is not performed, the tension and air pressure will be too low, causing problems in wire drawing. Pay special attention to this point.
7: The current control system is becoming more and more advanced, unlike the previous contactor relay control system, the more advanced things need more professional personnel to take care of them, the phenomenon of operators randomly adjusting the inverter parameters and the annealing board potentiometer on the spot, adjusting I don’t know how to adjust it back, which will cause unnecessary equipment complaints. When no professional electrician is present, it is strictly forbidden for the operator to play with the frequency converter and the annealing control board without authorization, and it must be clearly explained to the customer during the installation and commissioning of the equipment.
