A ball screw device includes a plurality of ball screw devices. In one ball screw device, a recirculation member is larger than the recirculation member in another ball screw device in terms of one mounting dimension of two mounting dimensions selected from a circumferential length of a part at a side of a pick-up opening portion in each pick-up portion, a circumferential length of a part at a side opposite to the pick-up opening portion in each pick-up portion, a circumferential length of a connection passage portion and an axial length of the connection passage portion, and the recirculation member is smaller than the recirculation member in the other ball screw device in terms of another mounting dimension of the two mounting dimensions, the other ball screw device being different in a diameter of a screw shaft from the one ball screw device.

A ball screw assembly is disclosed herein. The assembly includes a nut having an outer raceway, and at least one notch. A spindle extends inside of the nut, and the spindle defines an inner raceway. A ball-spring assembly includes a plurality of balls supported between the outer raceway and the inner raceway, and at least one reset spring engaged against at least one ball of the plurality of balls. At least one end-stop component is engaged against a terminal end of the ball-spring assembly and positioned within the at least one notch. A radially inner side of the at least one end-stop component abuts the spindle. A method of forming the nut for a ball screw assembly is also disclosed herein.

A ball screw device includes a screw shaft, a plurality of balls, a nut, a pair of guide members, and a transmission member. The nut has a pair of large-diameter portions and a small-diameter part between the two large-diameter portions. The two guide members are attachable to and detachable from an outer circumferential surface of the small-diameter portion in a radial direction and are located with a certain gap in the outer circumferential direction of the small-diameter portion. A fitting portion of the transmission member fits over the two large-diameter portions such that the fitting portion covers the two guide members while restricting radially outward displacements thereof. The fitting portion works with the small-diameter portion and the two guide members to define a circulation passage through which the balls are circulated. The transmission member is coupled to the nut.

A spindle nut (S) for a ball screw is conventionally designed as a hollow cylinder with a central-symmetrical middle longitudinal axis (Z). The spindle nut has an internal thread, which is designed as a ball groove (K) arranged on the cylinder inner surface. Pairs of load-relief bores (B) serve as substantially cylindrical channels for guiding the balls out of and into the ball channel (K) through the wall of the spindle nut. Each load-relief bore (B) is distinguished by a generatrix (L), which has an intersection point (C) with the thread base line of the ball channel (K) and constitutes the geometric continuation of the traveling path of a ball from the ball channel (K) into the load-relief bore (B). A tangent (T) to the cylinder surface (G) runs in a parallel manner at a spacing a >0 to the generatrix (L), both T and L being perpendicular to a common normal (R) to the middle longitudinal axis (Z).

A ball screw assembly includes a guider, an open nut, open shields, a first circulator, a second circulator, and ball circulating assemblies. The open nut is slidably fitted over the guider and includes an axial cylinder having an axial opening. Inner spiral channels of the axial cylinder and spiral channels of the guider form inner ball races. The open shields are coaxially fitted over the axial cylinder. An inner peripheral wall of each of the open shields and an outer annular wall of the axial cylinder form an outer ball race. The first circulator and the second circulator are disposed on the axial cylinder corresponding to the open shields. The inner ball races, first curves of the first circulator, the outer ball races, and second curves of the second circulator form ball circulating races, and the ball circulating assemblies roll in the ball circulating races.

An inner circulation ball screw includes a screw shaft, a nut, and a return member. The nut is disposed on the screw shaft to form a load path with the screw shaft. The return member is disposed in an accessory slot of the nut to form a non-load path connected with the load path to form a circulation path for circulation of balls. The return member has a ball-discharging channel provided with one end connected with an ineffective thread section of the nut and the other end communicating with a ball-discharging hole of the nut. Therefore, the balls are allowed to move to the outside of the nut through the ball-discharging channel and the ball-discharging hole for preventing the balls from being stuck in the ineffective thread section, thereby solving the problems of high resistance and damaging to related accessories.

The method for manufacturing a linear motion guide device includes a step of forming a long member (8) having a pair of side wall parts (51) and a bottom wall part (52), a step of attaching a track body (4) to the pair of side wall parts (51) of the long member (8), and a step of cutting away a base member (5) to which the track body (4) is attached by cutting the long member (8) together with the track body (4) into a desired length.

A method is provided for evaluating a maintenance requirement of a linear transmission device that is driven by a driving device. A control unit receives, from a sensing unit, a plurality of electric sensor signals that respectively correspond to multiple physical quantities of the linear transmission device or the driving device. The control unit calculates at least four correction factors based on the electric sensor signals, and calculates a service life of the linear transmission device based on the electric sensor signals and the at least four correction factors for scheduling maintenance of the linear transmission device.

A preload detectable screw device is provided which can detect preload with accuracy and can reduce the influence of generated heat on the output of a sensor. A screw device (1) includes a screw shaft (2), a nut member (3), a plurality of rolling elements (7, 8), at least one axial strain sensor (24) (B, D) that is attached to a surface of the nut member (3) and detects strain in an axial direction on the nut member (3), and at least one circumferential strain sensor (24) (A, C) that is attached to the surface of the nut member (3) and detects strain in a circumferential direction on the nut member (3). Preload of the screw device (1) is detected on the basis of outputs of the axial strain sensor (24) (B, D) and the circumferential strain sensor (24) (A, C).

An electric actuator includes: a motor section (5) including a stator (51) and a rotor (52); a driving-source output shaft (6), which is arranged on a radially inner side of the rotor, and is configured to output rotation of the rotor; and a speed reducer (2) connected to the driving-source output shaft. The driving-source output shaft (6) is hollow, and the speed reducer (2) includes a planetary-traction-drive speed reducer.