© Granlund Tools AB | Developed by Hamrén
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Switchboard: +46 16 16 72 00
After filling and reducing the elements, they always come out with a certain length variation. This variation is caused by:
Tube diameter tolerance
Tube hardness variation
Tap density (amount of MgO in the element)
The most influential factor is the tap density, i e the density of MgO in the element after filling.
There are two methods of compensating the length variations:
One method, ”cutting and stripping”, is to cut the element, uncover the pin and eventually also removing MgO from the end, in order to get space for the plug. This method is costly and wastes material.
The other method is length compensating by additional rolling of a part of the element. This method saves material (normally 1,5-2% depending on tube material). KOL-R uses this method.
• Same production capacity as KOR
• Working in line with KOR
• Saves material
• Close tolerances on length
• Easy to operate
• Eliminates disturbances in subsequent operations
The machine consists of the following parts:
– Transport path with measuring station
– Compensating mill with one pair of rolls and two inductive sensors
– Control panel with computer
– Hydraulic equipment
The machine will accept stainless steel, mild steel, copper and aluminium.
The element diameter is reduced additionally 0,1 mm (adjustable). The starting position of the reduction can be programmed. The length of the reduction depends on how much the element length is to be increased. The rolls will automatically go up when 90 mm is left of the element, even if the right length has not been acheived yet.
The length tolerance after compensation is very small, appr. ±1
Every element is measured as it comes out of the rolling mill, KOR. The length compensating machine, KOL-R, is adjusted to the same speed as the rolling mill. Therefore, KOL-R causes no slow down of the production. The transport path is adapted to take care of the maximum element length in the production (to be specified by the customer). The transport path (equals max element length) is 4m as standard, longer available on request.
The operating cycle is:
1.1 Normal Mode Elongation
The first measuring station is placed in the measuring path. The incoming length is
measured by the rotary encoder.
When the element reaches the proximity switch in measuring station 2, the rotary encoder in this station starts counting. The encoder in measuring station 3 counts backwards. When the measured difference in length between station 2 and 3 is equal
to the difference of length between set point and measured length in station 1, the reducing rolls move apart. The elongation is done by reducing the diameter of the element by approx. 0,1mm until the right length is reached.
1.2 Fuzzy Mode Elongation
The real time rolling, called normal mode, is a very accurate and secure method to lengthen elements of length 1000mm or longer. For elements shorter than 1000mm, elongation in real time mode can cause problems because of the distance between measuring station 2 and 3. Often the short rolling has to be used and the uncontrolled elongation has a big influence on the result.
In order to optimise the elongation for short elements GRANLUND Machinery AB has developped a rolling mode working with calculated rolling times for certain elongation, here called fuzzy mode rolling.
Switchboard: +46 16 16 72 00
E-mail: info@granlund.se
© Granlund Tools AB | Developed by Hamrén