Special operating conditions
Attention must be paid to the environment in which the flexible shaft will be used. For example, extremely high or low temperatures, moisture, corrosive influences, dust, magnetic fields, vibrations, etc. Such factors can influence the choice of materials for core and casing and their fabrication. Our technical departments will gladly offer their advice.
The following clarifications of choice of core, casing end coupling should also be made:
- Continuous or intermittent operation
- Fast toolholder change
- Shaft related to coupling or slide length
- Difference in length of core and casing
Corresponds to the angle of torsional deflection of a shaft under load. The desired maximum degree of torsional deflection is one of the parameters governing the required diameter and type of the shaft. The angle of torsional deflection is proportional to the torque and the length of the shaft.
Y = Torsional deflection at applied torque [°]
S = Stiffness factor according to table [°/10 Ncm/m]
Mb = Applied torque [Ncm]
L = Length of shaft [m]
Under this load, the shaft will twist or break. The figures are given in the sizing tables.
Reduction in degree of torsional deflection
The degree of torsional deflection in a flexible shaft varies proportionally with the torque. To keep the deflection, and the load as well, as low as possible, the flexible shaft should be operated at highest possible speed. If the speed is increased, the gearbox should be on the motor (drive) side; if it is reduced, it should be on the tool side.
The maximum speed of a flexible shaft is indicated in the table. The admissible speed is a function of the installation situation and of the torque to be transmitted.
As a rule of thumb: The shaft should be guided from 20 to 30 x . Not every protective casing is suitable for all applications (e.g. friction heat). For the shaft diameter to casing inside diameter ratio, as a rule of thumb 1:1.2 can be assumed.
In practice, depending on application and shaft diameter, flexible shafts with lengths of up to 15 m have proven successful.
In the case of high-speed rotary cores and cores longer than 5 to 8 cm, a protective casing is recommended to assure:
- Safety protection of personnel and equipment.
- Ability to handle shaft while running.
- Continuous guiding and support of the core. (Torsion shafts can be secured with guide rings.)
- Smooth operation.
- No “looping” of the rotating core during operation under torsional load.
- Shock absorption and absorption of push-pull forces.
The service required depends on the prevailing working conditions. With normal use without adverse conditions (moisture, heat, dust, etc.), the core should be cleaned and greased after about 200 operating hours. Under extreme conditions, e.g. wetness, cleaning and greasing are recommended after 50 operating hours.
X Last number:
1 for operation in clockwise (right-hand) direction
2 for operation in counter-clockwise (left-hand) direction
- Min. bend radius: The bend radius cannot be smaller than this value.
- Torsional deflection: Torsional deflection angle over 1 m shaft with torque of 10 Ncm.
- Breaking torque: At this load the shaft will break.
- Max. torque: Values applicable for straight shaft at speeds of 20% of maximum rated speed.