Datasheets

08/22 Our policy is one of continued research and development. We therefore reserve the right to amend, without notice, the specifications given in this document. (2019-9261a) © 2020 IMI International S.R.O. en 1.6.400.06 Sizing Rules and Formulas for loading values 1. Definition of the load cycle The load cycle includes all movements of the actuator. For every step, the following values must be defined: - Direction of the movement - Rotational position (alignment) of the carriage (top, side, down) - End position of the movement - External load mass - Offset position of the center of gravity of the load mass in relation to the carriage - Acceleration and deceleration - Maximum velocity - Constant external forces - Offset position of the force application in relation to the carriage - Possible pause times at the end of the movement Due to the high positioning accuracy of the Norgren ELION actua- tors, the number of steps in one cycle is not limited. 2. Calculation of the forces and torques acting on the actuator For a basic selection of the actuator, the knowledge of the acting forces during the load cycle is essential. For each movement of the load, all forces and torques acting on the actuator must be defined. This includes both external forces applied on the carriage and gravitational forces caused by the load mass applied. 2.1 Calculation of gravitational forces depending on alignment and direction The Norgren ELION rodless actuator is equipped with an elaborat- ed internal guiding system. To select the size of actuator fitting the application, all torques and forces acting on the bearings must be calculated. As a first step, the gravitational forces caused by the load mass and the moving mass of the actuator are transformed into the actuator coordinate system: 2.2 Calculation of torque and force values applied on the carriage The total forces applied on the carriage are calculated as follows: The torque values applied are calculated using these forces together with the lever arms through the offset of both the Center of Gravity of the external load and the application point of the external forces: The offset in z-direction must be corrected by the distance between the COG of the moving parts of the actuator and the top of the carriage -> z COG = z i + z 0 using the following values for Δz 0 : Size 48 60 80 100 Δz 0: 37 mm 47 mm 61.5 mm 75.5 mm To evaluate whether the forces and torques can be tolerated by the internal bearing system, they are normalized using the maximum tolerable values in every direction and then summarized. If the sum is <=1 the bearing is sufficiently sized for the load: The maximum values M x,max ,M y,max ,M z,max ,F y,max and F z,max depend on the velocity of the movement and can be estimated using the diagrams on page 11. P spindle Pitch of ball screw m a Acceleration/deceleration m/s² m mov,act Moving mass of the actuator kg m load Load mass applied on actuator kg Δx, Δy, Δz Distance of forces/loads to actuator centre m ß Position of carriage ° j Direction of movement ° g Gravitational acceleration m/s 2 3. Selection of the actuator and motor 3.1 Spindle pitch and number of supports The pitch of the driving spindle can be defined by the maximum velocity of of the load cycle. the load cycle. the load cycle. The correlation between the maximum stroke length and the max- imum velocity of the actuator must be considered as well as the different spindle pitch values defining the maximum velocity. To avoid oscillations of the spindle, the implementation of additional spindle supports can be necessary. Allowable values for the maxi- mum velocity with and without spindle supports can be found in the diagrams on page 9. Please note, that the zero stroke length of the actuators increases when spindle supports are installed. Using the values for stroke length and velocity, the maximum force necessary during the load cycle can be compared to the maximum force applicable to the actuator. Here, the direction of movement has to be considered to prevent buckling of the spindle. x z y z y Direction (Pitch) Alignment (Roll)

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