- Main Factors Affecting Spinning Quality
In the production of high-speed wire rods, the quality of the coils spit out by the laying machine often has tail flicks, large and small circles, out-of-round circles, larger or smaller coils, and uneven tiling on the air-cooled roller table, etc. These phenomena have a serious impact on Set rolls and bales at the back. The occurrence of these phenomena is related to the wear of the laying tube from the working process of the laying head, and the speed matching of the finishing rolling, pinch rolls, and laying head; wire temperature.
1.1 Spinning tube
The laying tube is installed on the laying disc and is a space spiral curve, which can be generally divided into three sections: one is the initial section, which is straight, and the wire does not undergo plastic bending deformation; the other is the deformation section, in which the wire is With the bending shape of the laying tube, the plastic bending deformation is carried out; the third is the shaping section, the wire continues to undergo plastic bending deformation and forms a stable coil, and the shaping section is very important for the shape of the laying coil. The exit end of the laying tube generally forms a certain angle with the laying disc surface, so that the spit-out coil can generate a forward speed. The silk tube smoothly spits out and spread on the air-cooled roller table. The nozzle angle of most laying machines is not adjustable, so when the rolling speed is changed, the horizontal forward speed of the spit out coil will be different, which will cause the coil to fall on the air-cooled roller table to deviate from the setting. the best condition, an unsatisfactory circle appears. Especially when producing small-scale wire rods, due to the large horizontal speed, the front part of the coil runs faster than the rear part. When the height of the tray is not adjusted properly, the coil will slant on the roller table. It is easy to form an oval shape.
1.2 Speed control of laying machine
The diameter of the coil spit out by the laying machine is not constant, and when the size is different, it will also affect the packaging quality. Therefore, it is also crucial to ensure that the diameter of the coil spit out by the laying machine is constant. When the wire passes through the spinning tube, the motion state changes from linear motion to circular motion and the linear speed is w. At this time, the rotational speed of the nozzle of the spinning tube is L. If w and L are equal in size and opposite in direction, the wire is spinning. The composite speed of the wire nozzle relative to the ground is 0. Since the spinning disc has a downward inclination angle, the wire rod performs a parabolic motion in the three-dimensional coordinates, and the vertical direction is free fall so that the coil diameter can be kept constant. In order to ensure that the wires of different specifications can meet VL=Vw in the whole laying process, to stabilize the coil diameter, generally, there are pinch rollers in front of the laying machine. The micro-tension control method is used to match the speed of the finishing mill, pinch roll, and laying machine; the second is the tail pinch feeding, and the small-sized wire rod is pinched at the tail speed to prevent the speed from rising when the tail exits the finishing mill. For specifications wire, the tail speed-up pinch is implemented to push the wire out of the laying machine to form a circle. When L≠w, the velocity of the coil relative to the ground in the direction of the disk surface is not 0, that is, the coil has an angular velocity relative to the ground, so a certain offset will occur during the falling process. When L>w, the relative angular velocity direction is consistent with the spinning direction of the laying pipe, and the coil will be leftward in the rolling direction; when L<w, the relative angular velocity direction is opposite to the spinning direction of the laying pipe, and the coil will be deflected to the right. When the coil is more serious to the left or right, it will collide with the sidewall of the air-cooled wire and damage the surface of the wire.
- Common phenomena and treatment methods in production
2.1 Spinning and tail flicking
Spinning tail flicking refers to the phenomenon that the tail of the wire cannot smoothly spit out from the laying tube and collides with the spinning disk surface rotating at high speed. Throw in the spinning tube. This is very common in the production of rolling small-sized wire rods (,5.5~,6.5), and the tail of the wire rod is often hung on the faceplate of the laying machine, the pallet, or the walls on both sides of the air-cooling line due to tail flicking. When transported away, it is often pressed and taken away by the head of the latter steel, which increases the labor intensity of the employees who cut the tail; interruption.
The solution is to properly adjust the throwing angle of the laying tube, but for those using the tail pinch process, it is necessary to ensure that the pinch rollers are pinch reliably, and also to extend the pinch roller’s tail clamping time and appropriately increase the speed of the pinch.
2.2 Spinning size circle
The large and small coils of spinning refer to the different diameters of the coils spit out by the laying machine. The reason is generally related to the speed matching between the laying machine and the finishing mill, which can be solved by adjusting the laying lead. When producing small-gauge wire rods, it is easy to have a large circle at the tail. This is because the speed of the tail will gradually increase during the process of leaving the finishing mill, while the speed of the laying machine changes very little, so the diameter of the tail circle becomes larger; If the wire rod, especially the ribbed steel bar is rounded, if the tail non-pinch process is adopted to ensure the surface quality of the wire rod, the speed of the tail end of the wire rod will decrease when entering the laying machine, thereby reducing the coil diameter. Therefore, it is recommended to micro-pinch the tail of the large-sized wire, provided that the clamping cylinder is controlled accurately to ensure that the surface is not damaged.
2.3 Uneven tiling
In order to make the coils evenly spread on the air-cooled roller table, in addition to the constant running speed of the roller table, another important factor is the spinning tube. When a laying tube produces multiple specifications of wire, the quality of the coils it spits out is often unstable, and it is prone to uneven tiling or large and small coils. This is because different specifications of wires have different spinning speeds and thus produce grooves with different trajectories in the laying tube, and the wires are prone to track deviation when they pass through such tubes. Therefore, the best solution is to use different laying tubes when rolling different specifications. When rolling small gauges, one tube can be used to correspond to one variety, and when rolling large gauge wires, one laying tube can be shared.
2.4 The spit circle suddenly falls from left to right
When the laying coil suddenly falls from left to right, the speed advance value of the laying head and pinch roll should be adjusted on the rolling parameter interface of the main console, so that R is stable = v/ω = R. /cosθ, so that the spit coil falls smoothly and evenly.
2.5 The coil is oval
When producing small-sized wire rods and the spinning temperature is too high, a circle-shaped ellipse phenomenon is likely to occur, because the wire rod is relatively soft. In addition, when the height of the air-cooled roller table is too low and the falling distance of the coils discharged from the laying machine is too large, an oval shape is likely to appear. When the forward throw angle of the laying nozzle is too large, the forward speed of the wire is large, which causes the coil to fall on the roller table obliquely. For the laying machine without the head positioning function, the coil is easily stuck in the gap of the roller table. A production accident occurs. Therefore, to solve these problems, it is necessary to analyze and improve on the three aspects of laying tube throw angle, roller table height, and laying temperature.
From the above, it can be known that the spinning tube and spinning speed are the main factors affecting the quality of spinning coils. In view of the phenomenon that occurs in the actual production process, corresponding measures should be taken to improve the quality of spinning and the appearance of products. The image must also be analyzed in combination with the actual situation of the production process. Due to different models and different levels of automatic control in each production plant, the problems in the quality of the coils have their own characteristics. The above analysis is only a very simple statement. Various situations will continue to appear in China, and at that time we will need to analyze, summarize and improve continuously according to the specific situation. Collect more actual data for classification settings.