|Sharp belt edge or other belt edge deformation
The belt edge is not in the round shape and condition as delivered
Sharp belt edges always causes soon or later belt edge cracks and as a result
Edge waves are caused by touching some parts at the press
>> a production stop <<
The reasons are e.g.
- belt edges are touching machine parts ( edge waves )
- if the belt edge has a troughing shape it will get damaged at the supporting rollers
- belt is over stretched at one edge caused by hydraulic defect at the tensioning drum
- drum layers are in bad conditions
- the edge sensors are not working properly
- the belt tracking system is not working properly
Sharp belt edges can be reshaped with the Berndorf Band BERMT tool
Belt edge cracks must be welded out immediately
Many cracks in a certain area only should be repairs by inserting a belt piece ( strip ) over the damaged length
or a patch by the PT 2001 or
a longhole patch by the Longhole Patching Tool
Inserting a belt piece over the whole belt width
Trimming the whole belt length
Belt edge waves can be shrinked by very skilled technicians
Describes the difference of a certain area of a belt ( e.g. the peak or the valley of a dent or wave ) in relation to the surrounding optimal flat area of the belt.
Is the difference between the minimum and the maximum thickness of the whole belt or a specific area
Special terms for the various job categories
Classification and general description of all jobs offered by Berndorf Band and VFE Service Department.
Dismounting – Mounting
The pulling out of belts respectively the installation of steel belts into the customers machine ( press )
Cutting a belt
The cutting of an endless belt at any point ( preferably ) at the existing cross welding seam , considering that the belt will be welded again to endless condition later.
Tracking a belt
This procedure happens after the belt installation. Herewith all the parts which influence the tracking of the belt ( pulleys, rollers, drums, sheaves and so on ) are to be adjusted in a way that the belt runs in stable / straight running ) conditions
With this method we are able to correct cross curvature deformations of belts in Double Belt Presses during production .
At Single Opening Presses no production is possible during this treatment due to the belt has to run continuously.
Flipping a belt
When a cross curvature has to be removed ( shot peening is not sufficient any more ) the belt will be cut, dismounted , turned around inside to outside , mounted and rewelded again.
Flattening of dents
When dents are to be flattened we try to work this plastic deformation as long as optimum flatness condition is achieved again ( professional hammering )
Is the treatment of a belt with heavy cross curvature deformations with the 3 - roll leveling device
We understand the correction of the cross curvature or longitudinal oriented deformations by using the flattening device ( 3 – roll leveling device )
Inserting of patches
Many damages can be repaired by inserting patches with round shape only , because of hard deformations or cracks
Regrinding of scratches
Scratches , which are the reason for future cracks are eliminated ( treated ) by local regrinding
Welding of holes
Small cracked areas with missing material ( e.g. holes ) can be repaired by welding using filler wire to close the hole.
Renewing a cross welding seam
It is possible to renew a cross welding seam ( caused by fatigue or overstress ) only with considering the possible tensioning allowance of the press. The old cross welding seam will be cut out ( with approx. 50 – 100 mm belt material ) and the both belt ends rewelded again.
Inserting a belt section
This will be done at large size damages or when the remaining tensioning allowance of the machine is not big enough anymore to cut out the damage and renew the welding seam.
Additional cross welding seam
Is necessary when the damage has to be cut out over the whole belt width and the existing cross welding seam cannot be used ( too far away from the damage )
Inserting of belt edge strips
When the belt edge damages in some areas are so heavily that many cracks appeared then we recommend to cut out the damaged area and insert a belt strip out of the available belt spare material .
Is the removal of a strip on the belt edge over the whole belt length.
This is necessary when extreme damages over the whole length appeared, the tracking behavior is too bad but considering a smaller belt width of the belt after trimming !!
With this method single overstressed areas ( e.g. bubbles ) will be repaired by thermal treatment
Changing of wear plates
We are able to deliver a new wear – or protection plate and to change the old one according to the customers requirements. ( in SOP )
Measurement examples for damages
After explaining some specific terms of damages and repair methods and to be able to describe a occurred damage
as exact as possible we want to continue to show and explain how
to measure and protocol the damage.
This should be done whenever a
- damage occurs , whenever
- you require and need a specialist from outside and
- to update your belt maintenance
- and history book for your own planning and safety.
The waviness describes periodical appearing of single flatness deviations of a belt by wave height and wave length. The wave height is the distance between the lowest point of the bottom and the highest point of the peak of a wave. The wave length is the distance between two adjacent peaks or bottom points.Waves are zones with bigger length than the surrounding area and can be snapped to the opposite side by hand pressure ( from outside to inner side and vica versa )
Waves can be located on the belt edges as well as in the center of the belt. The size of waves is mainly depending on the tension of a belt, therefore the tension of a belt must be considered in
any case. Waves are caused by thermal or mechanic overload of the belt material.
This can happen e.g. when the belt collides with the framework of the press or the belt is exposed to local overheat. Waves can be repaired only in very few cases
A waviness can be expressed by using the flatness index I.
I = H? / L? x 250.000 ( H = wave height , L = wave length , in mm )
(See 6.4.1. Service Handbook for table page 2 and 3)
The maximum allowed waviness of a new Berndorf belt (according to Berndorf - Standard Specification) can be found
in following table: