FIELD OF THE INVENTION
The present invention relates to Heat exchanger-heating element-form roller
manufacturing. This invention particularly relates to ease of manufacturing these
rollers with improved dimensional accuracy and wear resistant roller surface.
BACKGROUND OF THE INVENTION
Heating elements are used in Heat exchangers. Heat exchangers are provided
with multi layers of heating elements. These heating elements serve as a
medium for transferring heat from flue gas to air which is supplied to a boiler.
These heating elements are having irregular profiles to be rolled on a rolling
machine with special kind of rollers, known as form rollers. Heating element
profile needs to be very accurate to achieve the desired heat transfer. A wide
variation in the profiles is not allowed whether due to manufacturing process, or
due to the form rollers. Before any considerable change takes place in the
profile, the form rollers are replaced with new rollers. Profiles of the form roller
are quite complicated and difficult to make or recondition. So it is warranted to
have a roller made accurately to the required profile with sufficiently long life.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to propose an improved process
of manufacturing from rollers to roll irregular profiles of heating elements of heat
exchangers.

Another object of the invention is to propose an improved process of
manufacturing from rollers to roll irregular profiles of heating elements of heat
exchangers in which the rollers with dimensional accuracy, wear resistance and
long tool life, can be produced.
A further object of the invention is to propose an improved process of
manufacturing from rollers to roll irregular profiles of heating elements of heat
exchangers, which allows reduction in roller change time, maintenance time, and
machine down time.
SUMMARY OF THE INVENTION
According to the invention, there is provided an improved process of
manufacturing form rollers for profiles of heating elements of heat exchangers,
comprising the steps of :
- preparing a soft core made up of high carbon steel casting;
- weld depositing a first layer with hard facing electrode to impart required
hardness;
- providing a second layer on the surface, coated with hard chrome
plating/case carburizing to enhance the hardness;
- characterized in that profiles corresponding to that of the heating
elements are configured by hob cutters on the soft core of the roller, and
in that the rollers are manufactured as modular sleeves to restrict the

cumulative error when assembled so as to achieve accurate profile
dimensions.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1(a) Shows a split type Form Roller with four modules for rolling
of irregular profiles on heating elements of heat exchangers,
according to the invention.
Figure 1(b) Shows an assembled Form Roller particularly emphasing the
configured profile as per the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail with sequence to the accompanying
drawings.
The forming rollers are made up of high carbon steel casting. The profiles on the
form rollers are cut by using hob cutters. Hard facing of the profile portion is
done with hard facing electrode to required hardness. Surface treatment on the
profile is carried out by chrome plating/carburising to required depth and
hardness. The form rollers are made in Modular (split type) sleeves to achieve
high dimensional accuracy. The roller can be split into desired numbers and
assembled to required length.

WE CLAIM :
1. An improved process of manufacturing form roller for profiles of heating
elements of heat exchangers, comprising the steps of:
- preparing a soft core made up of high carbon steel casting;
- weld depositing a first layer with hard facing electrode to impart required
hardness;
- providing a second layer on the surface, coated with hard chrome
plating/case carburizing to enhance the hardness;
- characterized in that profiles corresponding to that of the heating
elements are configured by hob cutters on the soft core of the roller, and
in that the rollers are manufactured as modular sleeves to restrict the
cumulative error when assembled so as to achieve accurate profile
dimensions.
2. The method as claimed in claim 1 wherein the manufactured roller allows to
produce accurate profile on heating elements.

3. The method as claimed in claim 1 wherein roller change time and
maintenance time is reduced.
4. The method as claimed in claim 1 wherein the life of the produced form
rollers is extended.

ABSTRACT

The invention relates to an improved process of manufacturing profiles of
heating elements of heat exchangers, comprising the steps of : preparing a
soft core made up of high carbon steel casting; weld depositing a first layer
with hard facing electrode to impart required hardness; providing a second
layer on the surface, coated with hard chrome plating/case carburizing to
enhance the hardness; characterized in that profiles corresponding to that of
the heating elements are configured by hob cutters on the soft core of the
roller, and in that the rollers are manufactured as modular sleeves to restrict
the cumulative error when assembled so as to achieve accurate profile
dimensions.