Characteristics Of Tension Rolls

stretch roll

Since the high tension is required in the fast cold section, it is necessary to provide the tension roller device at the exit and inlet sections of this section, which is suitable to correctly separate the tension between this and other sections.

The characteristics of the tension roller are as follows:

Table 3.24.16 Characteristics of tension roller

One roller in each set of tension rollers (the third roller of the inlet tension roller and the first roller of the outlet tension roller) has a holding lock to maintain tension when the unit is stopped. The holding lock is equipped with brake blocks / pads and a pneumatic actuator.

Roller coating and convex

The furnace roll is delivered with a high roughness surface, in order to maintain good adhesion to the strip and to prevent skid, which can produce nodules and scratches. The purpose of high temperature coating: a) improve the wear resistance of the furnace roller at high temperature, improve the hardness, Cr25Ni20, Cr28Ni48, with the hardness drop, surface roughness decreases, cause the strip slip, the tension is not easy to establish; b) the second purpose is to resist nodules, nodulation is due to the strip surface; or due to the precipitation of strip steel in high temperature.

Spraying method: a), supersonic spraying technology, working temperature <500℃, using materials: Co base alloy, good low temperature wear resistance, oxidation resistance and good corrosion resistance; working temperature <900℃, using material: NiCr alloy, good thermal corrosion resistance and wear resistance under medium and high temperature conditions, corrosion resistance, corrosion resistance, micro vibration and grinding wear, good corrosion resistance, good wear and oxidation resistance at medium and high temperature.

B), Explosion spraying technology, working temperature> 900℃, using materials: alloy + oxide (metal ceramics), high temperature wear resistance, high temperature oxidation resistance, high temperature attachment resistance (nodulation resistance).

The design idea of high temperature resistant materials is: metal (metal alloy) + metal ceramics (non-metal). The best high temperature hardness is non-metallic ceramics. In order to ensure that the ceramic does not fall off, the metal phase (bonding phase) and metal ceramics (non-metal) (reinforcement item) should be added to ensure the strength, shedding resistance and strength, such as LCO-17,56. 1001000℃ water cooling tests.

The coating principle of the high temperature furnace roller of the furnace supplier is basically the same, that is, the heating section, partial heat section and cooling section adopt high temperature resistance coating, and the 950 or 1050℃ in the heating section and partial 050℃ heat resistance coating. Coated roller roughness is between 1 and 10 μm Ra. There are several coating suppliers and brands worldwide, as follows:

Table 3.24.18 List of hot furnace rollers' characteristics and suppliers and brands

Roller drive motor: The transmission system of strip steel is driven by motor and gear motor, and calculated according to the following basic data: maximum speed 420 mmHg, acceleration / deceleration rate 10 mp m/sec, braking rate 30 mp m/sec, maximum strip tension 15N / mm², Maximum strip tension difference 0.1 N/mm2 / roll (heating / heat), 0.3 N/mm2 / roll (cooling / outlet).