CZ2007793A3 - Process for producing sleeved rolls - Google Patents

Abstract

The method for producing bandaged cylinders with a bandage diameter of 700 to 2100 mm and their working length of 500 to 500 mm involves the application of a bandage to 100 to 400 degC on the cylinder cores and subsequent controlled cooling of the band on the roll to form a rigid, undetachable connection of the cylinder surfaces and bandages. The bandage heating is extra-fusible and is realized by an external source so that first the whole bandage is evenly overtaken and only the marginal parts of the bandage are locally warmed in the deployment phase so that the full-area clamping connection of the two parts occurs gradually during cooling from the center of length to the edges of the bandage.

Description

Method for producing bandaged rolls

Technical field

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for the manufacture of bandaged rollers for bandages of 0 700 to 2100 mm and a working length of 500 to 5000 mm for producing rolled products with high wear resistance and wear resistance.

BACKGROUND OF THE INVENTION

For the repair of metallurgical rollers, especially for sheet and strip rolling mills and for extending the service life, the method of bandaging is gradually abandoned, using a clamping connection based on the principle of thermal expansion of metals. Before the bandage was applied to the refurbished cylinder, the bandage was heated in the furnace and the bandage was subsequently placed on the cylinder. The fronts of the bandage, however, cooled faster, causing additional stresses along the entire length of the contact surface of the bandage with the cylinder core. For the production of the bandage, a material of usual chemical composition was used, which can be identical with the chemical composition of cylinders, ie tool carbon steel or steel with a chromium content of 1.5% and a carbon content of up to 0.8%. the rollers thus treated, mainly because of the higher level of longitudinal tension of the bandages and thus the lack of fracture resistance at the peripheral parts of the bandage, as well as the occurrence of the bandage awakening applied to the machined core of a mostly discarded roll. At the same time, lower efficiency against working wear of cylinders used mostly as supporting in quarto stands on belt and sheet metal abrasions This includes insufficient homeland resistance • · · * · ·

They are used for cracks or macro-cleavage and also for a relatively complicated process of heat preparation of the bandages for their application.

SUMMARY OF THE INVENTION

The above disadvantages are eliminated by the method of production of roll-rolled bandage rolls with high wear resistance of the working surface and resistance to the formation of surface imperfections, where both the roll core and the bandage are permanently connected. The bandage is made of tool or micro alloy steel, respectively. steels with a higher chromium content and a modified carbon content, with a chromium content ranging from 1.5-14% and a carbon content of 0.4% to 1.8% C. In order to achieve a uniform distribution of more complex chromium carbides with sufficient grain size of the structural grain, a combination of normalization annealing is used, together with multiple tempering heat treatment regimes, which ensure a fine-grained microstructure with uniform distribution of carbides.

The new production technology utilizes advanced finite element computational techniques to determine the curves of the outer contours of the cylinder cores, including the inner surfaces of the bandages themselves, so as to guarantee, after the heat treatment of the bandages, their deployment and clamping connection to the machined cylinder core. bandages, minimum level of accompanying residual internal stresses. The reliability of the clamping connection of the bandage and the core according to the invention is based on the preheating of the bandage to a temperature of 100 - 400 ° C, which is realized by an external source so that in the first phase

the bandage is preheated evenly by calculating the set temperature according to the size and weight of the bandage and the core. In the second deployment phase, the edge portions of the bandage are heated locally so that the full-area clamping connection of the two portions occurs gradually over the entire axial length from the center to the edges of the bandage when cooled. In addition to minimizing residual longitudinal stresses, the clamping connection thus obtained has at the same time sufficient resistance to the release effect when the rolls are heated during the rolling deformation process. This applies to both hot and cold deformation.

Overview of pictures

on the drawings

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated by the accompanying drawings, in which: Figure 1 is a schematic diagram of a bandage with measured parameters for a future clamp connection; Fig. 3 shows a method of attaching a bandage to a cylinder core, with a centering washer (3), an external heating coil of the bandage (4,5,6) and thermocouples (7). Giant. 4 shows a diagram of the composite end product of this process - a bandaged roller.

Embodiments of the invention

The bandage 1 is made of classic or microalloyed tool steel, respectively. steels with higher chromium content and modified carbon content, where the chromium content ranges between 1.5 - 14% and the carbon content is up to 1.8% and is heat treated. The basic parameters of the heat treatment of the bandage 1 are determined by the program “TT STEEL” so as to guarantee the achievement of fine-grained microstructure with uniform distribution of carbides, by determining the optimal quenching temperature and quenching end temperature by type

steel, the required hardness and at the same time so as to minimize the level of residual micro and macro stresses introduced, including limiting the residual austenite content, by including multiple tempering. The bandage (1) is positioned on the centering pad 3 so that the deviation of the bandage axis from the perpendicular direction corresponds to the given technological process. Thermocouples 7 are mounted in the individual heating zones of the bandage, which are then connected to a temperature recording sensor. A heating coil 4,5,6 is attached around the outer surface of the bandage 1, which is connected to the source. A hinge is attached to the core of the cylinder 2, machined to a shape according to mathematical calculation using the finite element method, which guarantees the suspension of the cylinder 2 core so as to maintain the perpendicularity of the axis of the core 2 and its parallel to the axis of the bandage. bandage 1 to the prescribed temperature of 100 - 400 ° C. the core of the roll 2 is transported over the bandage 1 and after checking the perpendicularity of the axis of the core 2 and the temperature of the bandage 1, the core 2 is inserted into the bandage 7. Check the gap between the core 2 and the preheated bandage 7 and check the depth of insertion of the core 2 into the bandage 1, which are determined by the technological process. The heating of the bandage 1 and the maintenance of the prescribed temperature is complete. The control thermocouples monitor the temperature drop in the controlled locations of the bandage L In case of an uneven temperature drop of the bandage 1, the quenching part 4 or 6 of the bandage 1 heats up more quickly.

Industrial applicability

The production method according to the invention can be used for the repair of prematurely discarded rollers with a bandage size of 0 700 to 2100 mm and their working length of 500 to 5000 mm for rolling rolled as a result of damage to their working surface. parts mainly in newly manufactured sets.

Claims (3)

PATENT CLAIMS Method for producing bandaged rollers having a bandage size of 0 700 to 2100 mm and a working length of 500 to 5000 mm as compensation for the reduced service life of prematurely discarded or newly manufactured rollers, characterized in that the bandage (1) is heated to 100-400 ° C on the cores of the roll (2) and the subsequent controlled cooling of the bandage (1) to the roll (2) creates a solid non-detachable connection of the surfaces of the roll (2) and the bandage (1). , so that the whole bandage is firstly uniformly preheated and only the edge parts (4) and (6) of the bandage (1) are locally reheated during the deployment phase so that the full clamping connection of both parts occurs gradually 1) 2. 3. Method for producing bandaged rollers according to claim 1, characterized in that it uses the finite element method to mathematically calculate and determine the forming curves of the rotational contact surfaces of the cylinder core (2) and the cavity of the bandage (1). (2) optimum stress suppression when the bandage (1) is applied to the core of the roll (2) with the stresses introduced into the surface layers of the bandage (1) due to deformation forces during the rolling process. Method for producing bandaged rollers according to claims 1 and 2, characterized in that forged bandage tool steel containing chromium is used for the production of bandage (1). 1.5 to 14% and a carbon content of 0.40 to 1.8% and other low levels of molybdenum and vanadium or other micro-alloying elements. Method for producing bandaged rollers according to claims 1, 2 and 3, characterized in that for heat treatment of the bandage the basic parameters are determined by the program TT Steel. The calculation ensures that a fine-grained microstructure is achieved with a uniform distribution of carbides and an optimal quenching and end temperature. hardening according to steel type and required hardness. At the same time, it minimizes the level of residual micro and macro stresses introduced, including limiting the residual austenite content by including multiple tempering.