An approach to a reduced-head hard disk drive (HDD) involves an actuator subsystem that includes a ball screw cam assembly wherein the number of starts of a multi-start screw equals the number of balls riding in a corresponding start. A stepper motor may be disposed within the screw, to drive rotation of the screw, which drives translation of an actuator arm assembly so that a corresponding pair of read-write heads can access different magnetic-recording disks of a multiple-disk stack. The actuator subsystem may further include a cam locking mechanism for coupling and decoupling the actuator arm with a coil support structure and corresponding voice coil, so that the cam mechanism is able to move under the control of a voice coil motor when input/output operations are performed and is able to move the actuator arm assembly during translation operations.

An approach to a reduced-head hard disk drive (HDD) involves an actuator subsystem that includes a ball screw cam assembly wherein the number of starts of a multi-start screw equals the number of balls riding in a corresponding start. A stepper motor may be disposed within the screw, to drive rotation of the screw, which drives translation of an actuator arm assembly so that a corresponding pair of read-write heads can access different magnetic-recording disks of a multiple-disk stack. The actuator subsystem may further include a cam locking mechanism for coupling and decoupling the actuator arm with a coil support structure and corresponding voice coil, so that the cam mechanism is able to move under the control of a voice coil motor when input/output operations are performed and is able to move the actuator arm assembly during translation operations.

A track member or a movable member constituting a motion guide device includes a rolling part formed of a metal material contacting with a plurality of rolling bodies and forming a rolling body rolling surface a, a mounting part formed of a metal material having a mounting hole for mounting an external member, and a track body or a movable body formed of FRP jointed with the rolling part and the mounting part and forming the track member or the movable member, and the mounting part and the track body or the movable body have joint holes, opened in a direction orthogonal to a lamination direction of FRP reinforced fiber sheets S forming the track body or the movable body at a time of the joint, and can be jointed using jointing means. An external member can be securely mounted to the motion guide device formed of FRP.

A rolling device includes: an inner member that has a raceway face; an outer member that has a raceway face facing the raceway face; and rolling elements that are disposed between both raceway faces in a rollable manner, wherein at least one of the inner member and the outer member has a space formed therein. Further, a method for manufacturing a rolling device including an inner member that has a raceway face, an outer member that has a raceway face facing the raceway face, rolling elements that are disposed between both raceway faces in a rollable manner, and a space that is formed inside at least one of the inner member and the outer member by a 3D printer.

A track member or a movable member constituting a motion guide device includes a rolling part formed of a metal material contacting with a plurality of rolling bodies and forming a rolling body rolling surface a, a mounting part formed of a metal material having a mounting hole for mounting an external member, and a track body or a movable body formed of FRP jointed with the rolling part and the mounting part and forming the track member or the movable member, and the mounting part and the track body or the movable body have joint holes, opened in a direction orthogonal to a lamination direction of FRP reinforced fiber sheets S forming the track body or the movable body at a time of the joint, and can be jointed using jointing means. An external member can be securely mounted to the motion guide device formed of FRP.

In a ball screw apparatus, a ball train including a plurality of main balls is housed in a raceway between a ball track of a ball nut and a ball track of a ball screw shaft. A coil spring housed in the raceway includes a first end that engages with an end of the ball train and a second end supported by a stopper (a first recessed portion, a protruding portion, or the like) of the ball nut. A stopper ball having a diameter larger than the diameter of the main ball is interposed between the stopper and the second end of the coil spring.

A ball screw device includes a screw shaft, a nut, a ball train including a plurality of main balls, and a plurality of coil springs disposed in the ball train. The nut moves from a first axial side to a second axial side while an axial force is applied to the nut by rotation of the screw shaft. The plurality of coil springs are more densely arranged on the first axial side than on the second axial side in the ball train.

In a ball screw apparatus, a ball train including a plurality of main balls is housed in a raceway between a ball track of a ball nut and a ball track of a ball screw shaft. A coil spring housed in the raceway includes a first end that engages with an end of the ball train and a second end supported by a stopper (a first recessed portion, a protruding portion, or the like) of the ball nut. A stopper ball having a diameter larger than the diameter of the main ball is interposed between the stopper and the second end of the coil spring.

A track member or a movable member constituting a motion guide device includes a rolling part formed of a metal material contacting with a plurality of rolling bodies and forming a rolling body rolling surface a, a mounting part formed of a metal material having a mounting hole for mounting an external member, and a track body or a movable body formed of FRP jointed with the rolling part and the mounting part and forming the track member or the movable member, and the mounting part and the track body or the movable body have joint holes, opened in a direction orthogonal to a lamination direction of FRP reinforced fiber sheets S forming the track body or the movable body at a time of the joint, and can be jointed using jointing means. An external member can be securely mounted to the motion guide device formed of FRP.

A ball screw device includes a screw shaft, a nut, and a housing that has a bottomed cylindrical shape and to which the nut is attached. The ball screw device converts rotational motion of the screw shaft into linear motion of the housing. The ball screw device is switched between a normal use state and a supply state. In the normal use state, along with the linear motion, a bottom portion of the housing reciprocates between a first position spaced apart from an end of the screw shaft and a second position closer to the end. In the supply state, along with the linear motion, the bottom portion of the housing is located in a third position even closer to the end of the screw shaft, such that grease present in the nut and the bottom portion of the housing is introduced to a radially inner side of the nut.