SU1678474A1 - Method for preparing rolls for operation during campaign - Google Patents

Abstract

The invention relates to rolling production and can be used in the preparation for the work of the support rolls of the quarto mill. The goal is to increase the rolls life by reducing the chippings due to the hardening of the end parts of the barrel. A new support roll made of 9XF steel is profiled, and then the surface layer is hardened to a depth of 0.00025 ... 0.000625 roll diameter, which for a roll with a diameter of 1600 mm is 0.4-1.0 mm. Hardening is performed by exposure to argon-arc and (or) plasma discharge. The use of these methods of hardening to a specified depth allows one to obtain the form of a hardened layer with an equidistant profile of the outer forming drum. After the profile of the barrel has been developed, the roll is thrown out of the cage and its working surface is roughened to obtain the required profiling, after which the hardening is carried out at a regulated depth. Using the method allows to increase the service life of the support rolls by 3-4 times. 1 tab.

Description

The invention relates to rolling production and can be used in the preparation for the work of the support rolls of the quarto mill.

The purpose of the invention is to increase the resource of the rolls by reducing the chippings due to the hardening of the end parts of the barrel.

The technical essence of the method consists in the fact that according to the method of preparing the rolling rolls for work, mainly the support rolls of the quarto stands, which includes the initial grinding to obtain the initial profile of the working surface of the barrel, perebrifenie working

surfaces after each roll out of the cage and subsequent hardening with a regulated depth of the layer, the hardening is carried out to a depth of a layer equal to 0.00025-0,000625 of the roll diameter, which is inserted after the initial grinding, while the inner boundary of the hardened layer is equidistant to the profile of the working surface barrels.

Experimental studies have established that the depth of the hardened layer, ensuring optimal performance of the support rolls, should be 0.00025-0.000625 roll diameter.

ABOUT

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To obtain such a layer, the most suitable is arc or plasma surface hardening.

Too thin hardened layer does not provide time to roll and leads to an increase in the specific consumption of rolls; An increase in the depth of the hardened layer of more than 0.000625 roll diameter leads to chipping due to low plasticity, especially in over-reinforced end pieces of the barrel.

Example. The new anvil roll with an outer diameter of 1600 mm made of 9ХФ steel is polished after the acceptance control to give the required profile depending on the location of the rolling stand in the mill line, namely, the roll reduction route.

After profiling, the roll is mounted on another roll lathe equipped with an argon arc burner and a VDU-301 rectifier. On this machine, the working surface of the support roll is hardened in the following modes: Operating current, A120-130

Arc voltage, V18-20

Roller rotation speed, m / h 50-200 Caliper travel speed, mm / min 2-20

Argon consumption l / min8-10

The table shows data on the wear of the working surface of the rolls, depending on the change in the depth of the hardened layer in the volume of optimal and beyond the limits.

The selected optimum of the argon-arc and (or) plasma discharge modes (as an option) and the depth of the hardened layer allows to obtain the profile of the inner surface of the hardened layer bordering

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with the main body of the roll barrel, equidistant profile of the forming barrel after repolishing. This favorably affects the leveling of wear along the length of the barrel, reduces the removal of metal during subsequent barrel profiling, and also provides the optimal combination of plastic and strength properties that prevent chipping.

 Using the proposal allows to increase the service life of the support rolls by 3-4 times by increasing the durability of chippings.

Claims (2)

1. Method of preparing mill rolls for operation during the operational campaign, mainly supporting rolls for quarto stands, which include the initial grinding to obtain the initial profile of the working surface of the barrel, repolishing the worn-out working surface after each roll out of stands and subsequent hardening with a regulated layer depth, characterized in that, in order to increase the roll life by reducing the crumbs of the barrel end parts, hardening is carried out with the depth of the roll of 0.00025-0,000625 of the nominal diameter of the roll, while the inner surface of the hardened layer perform an equidistant profile of the barrel, and the reinforcement operation is entered after initial barrel profiling. 2. A method according to claim 1, characterized in that the strengthening treatment is carried out with argon-arc discharge with a current strength of 120-130 A and arc voltage 18-20 V.