editor’s choice


The RVI roller screw is an inverted roller screw.


How do roller screws functIon and wHat are tHe optIons?


than hydraulic or pneumatic cylinder alternatives, both of which can be very complex and expensive to fit. At the same time the roller screw achieves considerably better positional accuracy compared with a ball screw. Environmentally the roller screw is less


noisy in operation, which compares well to pneumatic systems, but also has the obvious advantages of leak free functionality (air and hydraulic fluid) and less power consumption. The return on investment by purchasing


roller screw technology is offset through total cost of ownership and life cycle costs. It is realised through the reduction in the cost of maintenance, early replacement and resulting downtime.


The RVR roller screw is a design which incorporates recirculating rollers.


Roller screws use rollers to transmit force from the nut to the shaft. The main elements are the screw, the nut and the satellite rollers. Moore International supply the ROLLVIS Swiss range of roller screws which are used to transform rotary movements into linear movements and vice versa. The rolling elements are threaded rollers between the screw and the nut. The high number of points of contact enables satellite roller screws to support very heavy loads. The ROLLVIS range comprises satellite


roller screws with no recirculation (RV and HRV types), inverted roller screws (RVI type), Differential roller screws (RVD type) and screws with recirculating rollers (RVR type). Bearing units are also proposed to equip the different roller screw designs. The RV screw is a high precision, robust


assembly where the rollers do not recirculate, thus enabling a very stable driving torque. Special gears are designed on the rollers and nut to maintain a good kinematics even in the most severe conditions. The internal thread of the nut is identical to that of the screw. To ensure no axial


movement occurs between the nut and the rollers, there is a single-start thread with precise angle accuracy between the nut and the rollers. The RVR roller screw is a design which


incorporates recirculating rollers. The rollers are guided within a cage and their motion is controlled by a set of cams. This design combines extremely high positioning accuracy, resolution and stiffness while capacity ratings are at the highest thanks to a robust thread geometry. This concept is perfect for all applications that need a very high accuracy under small or moderate speeds. The RVI roller screw is an inverted roller


screw. Whilst it is based on the same principle as the RV design and delivers the exactly the same level of operational performance, the rollers do not move axially along the shaft and stroke is travelled within a longer nut. This concept follows specific design rules which enable higher capacity ratings with smaller leads which consequently reduces the driving torque, optimises compactness and makes a direct guiding of the shaft possible. The RVD roller screw is ideally suited for


high precision applications when high accuracy is required. Its components are specifically designed and adjusted to allow extremely thin leads down to 0.02 mm. Shorter stroke applications are best suited for this type of roller screw. The HRV roller screw is designed for very


high load applications and for extended life. This design provides more contacts in the assembly than the RV type and has a different thread profile. The nuts are also longer than in the standard RV version. The HRV series is suitable for larger diameters and consequently the range is not available in split nut format or with internal preload. Only standard or reduced backlash options are available.


Moore International www.mooreinternational.co.uk


UKManufacturing Summer 2021 9


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44