Due to the long work time of the rolls, the surface of the rolls have cracks, peeling defects, etc., or the rolls body diameter does not meet the size requirements. At this time, the repair (such as surfacing) technology is selected to restore the original size of the rolls. This is called roll repair.

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Halnn BN-S20 grade CBN inserts realized turning surfacing roll instead
of grinding
Due to the long work time of the rolls, the surface of the rolls have cracks,
peeling defects, etc., or the rolls body diameter does not meet the size
requirements. At this time, the repair (suchas surfacing) technology is selected
to restore the original size of the rolls. This is called roll repair. .
As the main part of the rolling mill, the qualityof the rolls directly determines the
processing efficiency of the rolling mill and the quality of the product, and the
rolls belong to the consumable parts, so the quality of the rolls also determines
the consumption of the rolls. When the rolls are defective or the size is not up to
standard, the surfacing technology is often used to repair the rolls body and
journal of the rolls, which not only reduces the productioncost of the rolling mill,
but also improves the processing efficiency.
Here is a brief introduction to the matters needing attention before repairing the
rolls and how to process the repaired rolls?
1. Before the rolls are repaired
(1) Clean the surface of the rolls: If the failure form of the rolls are crack, the
crack should be completely removed;
(2) Ultrasonic flaw detection: Check whether the rolls have any defects
affecting the use, especially whether the crack is cleaned;
(3) Deheat the rolls: Reduces the cooling rate of metal and heat affected zones
during surfacing, reduces the tendency to harden and reduces weld stress. The

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preheating temperature is determined by the carbon content and alloy content
of the rolls material and the material of the weld material.
2. Rolls repair
The repair method is according to the product, material, specification and
failure situation of the rolls. Such as electrode arc welding surfacing is suitable
for the repair of small batches and irregular rolls, as well as on-site repair.
Electroslag surfacing is suitable for surfacing of large flat rolls. Among them,
submerged arc welding is a kind of surfacing method widely used in surfacing
rolls, which can realize automation and mechanization, and has no arc
radiation and good working conditions.
3. After the rolls are repaired
After the rolls are repaired, heat treatment is performed to eliminate welding
stress, improve rolls performance, and prevent delayed crack generation. The
rolls are then machined to restore roll surface size and roughness
requirements.
There are two methods for recovering the surface size and precision of the
rolls. With the continuous development of modern technology and the
continuous development of the tool industry, it has developed a cutting tool
material that can improve the efficiency of the turning. In particular, Halnn
BN-S20 grade CBN inserts developed by Halnn Superhard can realize
high-efficiency processing of surfacing rolls, improve processing efficiency and
reduce processing cost.

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As a provider of CBN inserts industry solutions and an advocate of
environmental protection, Halnn constantly innovates and enhances its core
competitiveness, and its service targets are gradually expanding to various
machinery industries. We are always providing our customers with high quality,
high performance CBN inserts products which can quickly meet increasingly
diverse needs.
For large rolls, the turning instead of grinding process is generally selected. For
example, the precision of the roll after repairing the BN-S20 grade CBN inserts
can reach Ra0.4. However, if the roller requires an accuracy of Ra 0.4 or higher,
it is recommended to grind after turning.