Reasons and analysis of copper wire disconnection during wire drawing

Understanding and being familiar with "Causes and Analysis of Copper Wire Disconnection" will help the wire drawing factory to make a reasonable and objective analysis and judgment on the reasons for copper wire disconnection in the production process. Types of broken wires and their discussion Central burst Central burst: The broken wire breaks from the central part of the copper wire, with a sharp cone at one end and a sharp hole at the other end. The hole in the center burst is most likely to be mistaken for the broken line of the bubble. When the wall of the hole burst in the center is enlarged, it can be found that the material itself presents a concave and convex tear phenomenon due to the influence of external force.

Types of Central Bursts

1) Central burst caused by excessive oxygen content in the copper rod (greater than 6000PPM);

2) Central burst caused by inclusions;

3) Central burst caused by poor wire drawing equipment (such as inappropriate eye mold advance angle); the formation process of central burst, observe the metallographic photos of the longitudinal section of the central burst fracture line, we found that the cuprous oxide particles were originally arranged neatly Due to the influence of stress, it is twisted, deformed and uneven, and the formation process of the broken wire is observed from the metallographic diagram (the figure shows that the cuprous oxide particles have been obviously twisted and concentrated, and tiny cracks have occurred. If this phenomenon occurs during heavy pulling, although there is enough strength to maintain the continuous line, as long as external force is applied in the subsequent middle pulling process, it will inevitably cause wire breakage. Similarly, if there is internal injury during middle pulling , there must be a problem with Selah. (When a wire breakage occurs, the drawn copper wire is hard and brittle, and it breaks when it is bent, which is often mistaken for poor copper quality.) The prevention of central bursting is due to the continuous casting and tying of copper rods with relatively stable quality, and other reasons for breaking There are few lines, so prevention of central burst is especially important.

Prevention method

1) Regularly check the deformation angle of the eye mold, if the wear is too large, it should be replaced in time

2) Regularly check the concentration, temperature, PH value and electrical conductivity of the drawing liquid, and add or replace the drawing oil in time.

A. Check the tower wheel of the wire drawing machine and replace it in time when it is seriously worn.

B. Bubble disconnection (mainly due to copper) The section of this disconnection is in the shape of a hole, and the surface of the hole is very smooth without bulge or cracking.

The reason for the formation of bubble breakage is due to improper control of hydrogen during casting and poor cooling, resulting in shrinkage cavities. If the holes are small, they may be closed in the subsequent hot working process. If the holes are large, they cannot be closed, resulting in bubble breakage. Wire.

C. Inclusion disconnection (mainly due to copper) Inclusion disconnection is a more common type of disconnection. From the appearance, it can be divided into two categories, one is the disconnection with inclusions, the other The class is the broken wire where the inclusions are missing.

D. "V"-shaped broken wire The main feature of this broken wire is that there are continuous "V"-shaped cracks on the surface of the copper wire, and the tip of the "V" character is the direction of stretching. The main reason for the formation is the improper angle of stretching the eye mold, or when the copper wire does not enter the eye mold horizontally but enters at a certain angle, the excessive friction between the wire and the eye mold may also cause "V"-shaped cracks. From the metallographic diagram, it can be observed that the cuprous oxide particles are arranged in a twisted wave shape with the "V"-shaped crack as the base point under the action of external force. In addition, if the oxygen content of the copper surface is too concentrated, "V"-shaped cracks are more likely to occur, which will eventually lead to wire breakage.

E. Copper thorns or splinter (mainly due to copper) The occurrence of copper thorns is similar to inclusions, which are produced during rolling or casting, so they can be divided into cast (CAST-IN SLIVER) and rolled (ROLLED- IN SLIVER) two, the copper thorns are cast when the cooling is improper or the oxygen content in the copper water is too high; the copper thorns are formed from the extension process, the trimming machine is not adjusted properly, or the gap between the rollers is not adjusted properly, resulting in scratches etc. Generally speaking, copper thorns or long splits are related to cuprous oxide particles that occur during casting or drawing, because the presence of cuprous oxide prevents the copper rod from closing the cracks during processing, so the copper wire surface produces thorns after stretching. Or long slivers, causing wire breakage in severe cases.

F. Tension wire breakage Tension wire breakage is a common wire breakage in the stretching process. The wire breakage feature is that the broken end is cup-cone-shaped or pointed-cone-shaped. Because the tensile force is greater than the tensile strength of the copper wire itself, the wire is broken. . Causes: Poor lubrication during copper wire drawing, improper angle of the eye mold, accumulation of copper powder in front of the eye mold, excessive surface reduction rate and improper speed matching may cause tension disconnection.

G. Copper powder breakage There is a considerable amount of copper powder in the drawing lubricant. When drawing, the copper powder will accumulate at the corner of the eye mold, so that the copper wire will be clamped in the eye mold and cause wire breakage; in addition, copper thorns will peel off and accumulate in the eye mold. It will also cause disconnection before the mold.

H. Connector disconnection The connector disconnection shape can be divided into four categories: fish mouth-shaped disconnection, and the other three are flat-headed, oblique-edged, and spiked. The biggest reason for the disconnection of the joint is that the cuprous oxide particles are too concentrated in the connection part, or the temperature is too high during wiring, which causes the growth of grains. In addition, the lace is not cleaned cleanly after welding, which will also cause wire breakage.

I. Mechanical damage and wire breakage The main reason for this kind of wire breakage is that the copper rod or copper wire is not well arranged and causes disordered lines. Before entering the wire drawing machine, the disordered lines form entanglement and knots between the lines and cannot enter the wire drawing machine. Eye mold and disconnected.

J. Twisting and fuse Twisting: The wire is broken due to torsion, which most often occurs on the stranding machine for the production of communication cables. Fusing: This phenomenon mainly occurs in the continuous annealing machine. Due to improper tension adjustment or internal defects of the copper material, sparks are generated between the wire and the guide pulley, and the surface of the copper wire is melted at the place where the spark occurs, which may cause wire breakage in severe cases.

K. Eye mold scratches The management of the drawing eye mold directly affects the wire breakage rate and processing cost. If the inner hole of the eye mold is not smooth, it will cause serious continuous scratches on the surface of the drawn wire and cause tension disconnection.

Analysis and Solution of Abnormal Causes of Wire and Cable in Drawing Process

1. Causes and solutions of disconnection

The joint is not strong: adjust the current of the butt welding machine. Power-on time and pressure. Improve welding quality.

Impurities in the wire: Strengthen the acceptance of raw materials.

Unreasonable mold matching: adjust the mold to eliminate the phenomenon that the deformation process is too large and too small.

The shape of the die hole is incorrect or not smooth: repair the die strictly according to the standard, and the sizing area should not be too long to ensure the smoothness of the die hole.

The reverse tension is too large: adjust the number of turns of the winding on the drum.

Crimping on the drum: Adjust the number of turns of the winding on the drum, and correct the worn drum.

Poor lubrication: Check the lubrication system, determine the composition and temperature of the lubricant.

Wet aluminum poles: Prevent aluminum poles from getting wet, and wet aluminum poles are not used temporarily.

2. Reasons and solutions for incorrect size and shape

Die hole wear: Measure the wire diameter frequently and replace the die when out of tolerance is found.

Wire thinning: adjust the die matching to improve the lubrication effect.

Wrong mold: measure the wire diameter after threading.

Wire scratches: Check the quality and lubrication of the die holes.

The mold is skewed: pay attention to straighten it when the mold is loaded, and check the mold base.

3. Causes and solutions of scratches, bumps and scratches

There is a jumper phenomenon on the conical drum: Trim the surface of the drum, and check the angle correctly.

Grooves on drum: Remove drum to repair and polish.

Where there is a damaged wire on the equipment: the drum wheel interface is not flat, and the guide wheel is not flexible in rotation.

Spools collide with each other: The spools should be placed in a "T" and separated from each other during transportation.

Uneven ground: Renovate the ground and lay steel plates.

The line is too full: stick to your post, concentrate your energy, and sell according to regulations.

4. Causes and solutions of peeling, pitting, triangular mouth and burr

The wire has flash, inclusions and shrinkage holes: strengthen the inspection, and the unqualified ones will not be put into production.

Die holes are not smooth, deformed, etc.: Strict inspection, unqualified molds will not be used on the machine.

Poor lubrication: Improve the lubrication effect.

The drum is not smooth and the sliding rate is too large: Polish the surface of the drum and adjust the matching mold.

5. Causes and solutions of ripples and snakes

Improper mold matching: Adjust the mold matching, and the deformation degree of the finished mold should not be too small.

Serious vibration of wire drawing machine: overhaul and reinforce equipment to eliminate vibration.

The wire is shaking violently: adjust the tension and keep the wire take-up speed stable.

The shape of the die hole is not suitable: the length of the sizing area should be appropriate, not too short, or even not.

Lubrication supply is uneven and not clean: Ensure that the lubricant is supplied evenly and filter the lubricant for use.

6. Causes and solutions of continuous scratches on the wire

Wire scratches: Check all parts that are in contact with the wire, such as guide rollers and cable bars.

The temperature of the lubricating fluid is too high: strengthen the cooling, and use forced cooling if necessary.

Lubricant with high alkali content and uncleanness: regularly test to maintain the composition of the lubricant and ensure its cleanliness.

The die hole is not smooth and defective: strengthen the repair and management of the die, and the unqualified die will not be installed on the machine.

The lubricating area of the die hole is blocked: the lubricating fluid should be filtered to eliminate metal chips and various impurities in the lubricating fluid.

  7. Causes and solutions of oxidation, water stains and oil stains

Insufficient lubrication and high temperature of lubricating fluid: ensure sufficient supply of lubricating fluid and strengthen cooling of lubricating fluid.

Lubricating fluid splash: block the splashing part, and use felt to wipe the line at the exit of the finished line.

The storage site is not clean, and the oily gloves stain the wire: Adhere to 5S management to ensure the cleanliness of the workplace.

8. The causes and solutions of the full, partial, disordered, tight and loose winding line

Improper adjustment of the cable: Adjust the width and position of the cable according to the specifications of the take-up reel.

Improper take-up tension: Adjust the take-up tension and take-up speed.

There is a fault in the wiring mechanism: observe carefully and eliminate it in time.

Irregular take-up reel: Choose a qualified reel to put on the machine.

The take-up line is too full: strengthen the monitoring, in case of automatic disk change, reset the number of unloaded disks or overhaul the equipment.

9. Causes and solutions of unqualified performance

Unqualified mechanical properties such as tensile strength, elongation, and bending: the total deformation degree is small, the raw materials are unqualified, and the reason for uneven deformation will cause unqualified mechanical properties. Therefore, qualified raw materials should be selected, the total deformation degree should be increased, and the wire drawing should be controlled. conditions such as temperature rise during the process.

Unqualified resistivity: mainly due to unqualified raw materials, followed by improper annealing process.