Page 1 GSI, Hydraulic Actuators for PANDA Target Spectrometer Jost Lühning, GSI Darmstadt Functional Specifications for moving the TS: Two synchronous actuators Each with at least 100 kN force over full stroke length Maximum length of actuator must be lower than 2 meters The letter specification results from the space available in the beam area for the case that only pushing should be applied. In case both pushing and pulling should be applied the maximum length could be bigger. Also in case that the cylinder could be mounted inside of the platform beam. Two ways to achieve synchronization of actuators: Master-slave configuration Advantage: no PLC and no travel distance measuring necessary. Disadvantage: Master cylinder has to be bigger than either of 2 independent cylinders. For the ability to work in both directions with full force also the slave cylinder would have to be bigger. According to ACON-hydraulic (s. deviation from synchronous move (due to tolerances in cylinder diameters) is less than 0.5%. Of course it is desirable to always know the position during traveling, there are LASER distance sensors available with a linearity of 2 mm over 15 meters. PLC-control of independent actuators with travel distance measuring More precise, but also more complicated and expensive. Longer period of vocational adjustment necessary. Compared to Master-Slave option more prone to failure.

Page 2 GSI, Master-Slave configuration with two double-rod cylinders Synchronous movement of upper and lower cylinder, (p 2 -p 0 ) ∝ F 2, (p 1 -p 0 ) ∝ (F 1 +F 2 ) master slave F1F1 F2F2 p2p2 p1p1 As working hypothesis the option with PLC-control will be assumed in the following. p 0 (=0)

Page 3 GSI, Precision of Synchronous Move The precision that has to be guaranteed for a synchronous move depends on the number of guide rollers in a system and on the clearance between guide rollers and rails. Ideally guide rollers should exert only small side forces on the rails. Moments of forces have to be avoided. clearance rail guide rollers move direction forces of synchronous actuators bottom view Heavy weight rollers

Page 4 GSI, Principle considerations for the operation of the actuators How big are the forces which have to be applied? The friction of heavy-weight rollers on hardened steel rails is less than 5%. Forces due to unevenness of rails are negligible. Minimum Power of the hydraulic pump? At least 1000 Watts ( in order to achieve a velocity of 30 cm/minute ). Where is the center of the friction forces? Assumed: a few centimeters above the rails - near to the rotation axis of the loaded layer of rolls. Suggesting position for actuators? Just above each rail – in order to minimize any moment of force. Mounting of actuators? Pivoting mounts in order to avoid side loads ( avoid additional friction and wear on the rod bearing, s. ). Usually a spherical eye is chosen for the piston rod. Trunnion mounting is possible for the cylinder body.

Page 5 GSI, Estimation of Price and Weight of a single Cylinder The price given in the following is taken from a list of a leading German manufacturer (year 2009). It is valid for a standard double acting cylinder with piston diameter 100 mm and working pressure 25 MPa. The price depends on the nominal stroke length. Less well-known manufacturers offer cheaper cylinders. The price for a Master-Slave pair with a stroke length of 150cm could be lower than 4k€.

Page 6 GSI, Anchoring of Actuators Favorite configuration: Cylinders mounted to platform beams, piston head pressing on anchor which is fixed at the bed plate of the rail segments rail segment bed plate FEM-model of actuator anchor, symmetry about vertical x-y plane, contact only to ground plate, not to rail segment

Page 7 GSI, Anchoring of Actuators Force transfer principle: friction locking or positive locking? Friction locking would require at least 10 times the value of the horizontal anchor force. With 10 tons to hold, for instance, a total of at least 12 screws of size M16 would be needed. This does not seem convenient for a repetitive displacement of the anchor. Positive locking would require a surface which could be loaded up to 50 MPa on average. One hole on each side of the rail, with diameter 50 mm and depth 20 mm, would be sufficient.

Page 8 GSI, Actuators for the Doors Boundary Conditions: Weight of each of the 4 doors: 250 kN (mass 25 tons) Moving force (each): at least 10 kN Travel path of each door (for full access): 2.3 m Work needed to move each door aside: at least 23 kNm This is too much to be performed manually Actuator type: Hydraulic cylinder Screw ball assembly for instance Bosch-Rexrodt EMC (catalog no. R ) Actuator length: Stroke length 2.30 m or 1.15 m? According to a buckling length table of a leading manufacturer the piston diameter of a certain type would have to be: 63 mm for stroke length 2.3 m (pressure 3.3 MPa), 40 mm for stroke length 1.15 m (pressure 8.0 MPa).