Views:3 Author:Site Editor Publish Time: 2018-02-27 Origin:Site
Cemented carbide roll rings, composed of tungsten carbide and binding metal, is one kind of tool material with high hardness and good wear-resistance. In order to make full use of the above advantages of cemented carbide roll rings, the manufacturer of high-speed wire rod shall pay more attention to the following items during the course of purchasing and using it.
1.Make the correct choice for the cemented carbide used by the finishing mill.
Before determining the grade of cemented carbide for every stand, we shall have a thorough understand about their properties so as to make the correct choice(Please refer to the preceding paragraph).
2.Installation of cemented carbide roll rings
The sleeve insertion and assmbly of cemented carbide roll rings shall be carried out in accordance with the requirements of precision. There shall be appropriate space between the roll rings and axle or between the roll rings and sleeve. The fit is neither tight nor loose. You should check whether the roll rings conforms to the technological requirement and clean the mounting surface of roll rings,sleeve and axle before the installation. It is prohibited to beat the roll rings with hammer or other hard things while assemblying.
3. Requirement for the cooling of roll rings and cooling water during the course of rolling
Because of the negative effect of heat corrosion, thermal fatigue and thermal stress, the net-shaped thermal fatigue
crack usually appears while the collar working. With the increase of cracks, small parts may come off and even the roll
rings is broken. We adopt the cooling method to reduce the bad effect, prevent the cracks from stretching and prolong
the durability of rolling groove, which plays an positive role on the cemented carbide roll rings. The parameters of cooling
water are as follows: temperature no more than 35°C, pressure of 0.4-0.6Mpa, volume of 24-30m3 per stand per hour,
radical direction for spraying water, the angle of 15-30° between the spraying direction and rotating direction of roll rings.
The water is twice as wide as the rolling groove and directly sprayed into the groove without scattering.
Water quality requirement：
For YGH series medium or weak alkali water of PH>7.2
For YGR series or PH<7.2 weak acid water of PH>7.2
The content of solid particles in the water<15 milligram/L
4.Determine the reasonal yield
It is inevitable to find the microcrack on the rolling groove. The microcrack will gradually extend, stretch and deepen. The
groove shall be repaired immediately while the depth of crack reaching 0.2-0.4mm. Otherwise, the crack will deepenquickly, which leads to a risk of broken roller. The range of normal yield is regulated as follows:
Stands of pre-tfinishing rolling mill ： (5000-7000)tons
1 -2 Stands of finishing rolling mill ： (2000-3000)tons
3-4 Stands of finishing rolling mith(2000-3000)tons
5-6 Stands of finishing rolling mill ： (1500-2500)tons
7-8 Stands of finishing rolling mill ： (1500-2500)tons
9-1 OStands of finishing rolling mill ： (1200-2000)tons
Stands for reducing diameters： (1000-1500)tons
5.Repair of groove
It is normal to find the microcrack on the rolling groove. The groove shall be repaired immediately while the depth of crack
reaching 0.2 mm. It is necessary to prevent the roller from being broken. While repairing, we must ensure to remove the
crack thoroughly. Otherwise, it will bring a potential risk to next rolling. It is difficult and inconvenient to check if the
surface is polishing. To ensure the complete remove of microcrack, we can increase the grinding quantity. Under the
normal condition, the repair is controlled in the range of:
Roll rings for stands 9-10 of finishing rolling mill(0.4-0.6)mm
Roll rings for stands 1 -8 of finishing roiling mill(0.7-1.2)mm
Roll rings for s~nds of pre-finishing rolling mill(1.2—2.0)mm