Abstract: Provided are a sintered ceramic and a ceramic sphere which are inhibited from suffering surface peeling due to fatigue resulting from repetitions of loading and can attain an improvement in dimensional accuracy when subjected to surface processing and which have excellent wear resistance and durability.

Abstract: Provided are a sintered ceramic and a ceramic sphere which are inhibited from suffering surface peeling due to fatigue resulting from repetitions of loading and can attain an improvement in dimensional accuracy when subjected to surface processing and which have excellent wear resistance and durability. A ceramic-sphere inspection device is also provided with which a ceramic sphere is inspected for a flaw present in the surface layer and for snow flakes without destroying the ceramic sphere. The device is a ceramic-sphere inspection device (100) in which a ceramic sphere (S) is rotatably supported in a given position and illuminating light emitted from a light projector (110) is detected with a light receiver (120) to evaluate the state of the inner part of the surface layer, and has been configured so that the light receiver (120) does not detect the light emitted from the light projector (110) and reflected at the surface of the ceramic sphere.

Abstract: Provided are a sintered ceramic and a ceramic sphere which are inhibited from suffering surface peeling due to fatigue resulting from repetitions of loading and can attain an improvement in dimensional accuracy when subjected to surface processing and which have excellent wear resistance and durability. A ceramic-sphere inspection device is also provided with which a ceramic sphere is inspected for a flaw present in the surface layer and for snow flakes without destroying the ceramic sphere. The device is a ceramic-sphere inspection device (100) in which a ceramic sphere (S) is rotatably supported in a given position and illuminating light emitted from a light projector (110) is detected with a light receiver (120) to evaluate the state of the inner part of the surface layer, and has been configured so that the light receiver (120) does not detect the light emitted from the light projector (110) and reflected at the surface of the ceramic sphere.

Abstract: Provided are a sintered ceramic and a ceramic sphere which are inhibited from suffering surface peeling due to fatigue resulting from repetitions of loading and can attain an improvement in dimensional accuracy when subjected to surface processing and which have excellent wear resistance and durability. A ceramic-sphere inspection device is also provided with which a ceramic sphere is inspected for a flaw present in the surface layer and for snow flakes without destroying the ceramic sphere. The device is a ceramic-sphere inspection device (100) in which a ceramic sphere (S) is rotatably supported in a given position and illuminating light emitted from a light projector (110) is detected with a light receiver (120) to evaluate the state of the inner part of the surface layer, and has been configured so that the light receiver (120) does not detect the light emitted from the light projector (110) and reflected at the surface of the ceramic sphere.

Abstract: A ball-point pen is made to satisfy the following relationships: −2.5<Rs×Rku<1.2 and 0.005<Ra/S<0.012, where respective values of Ra or arithmetic average roughness; Rsk or skewness; Rku or kurtosis, which are three-dimensional parameters; and S or average spacing of local peaks which is a two-dimensional parameter, are obtained with a cut-off value set at 0.00132 mm, when surface roughness of the ball is represented by a value in one arbitrary location on the ball surface, namely, inside a circular region thereon whose diameter is 10% of the nominal ball diameter.

Abstract: A ball screw device utilizes spacers having concave ball-contacting surfaces with distributed protrusions or dimples. Balls having needle-like recesses may also be used. The spacers are provided in two thicknesses, and the relative numbers of the thinner and thicker spacers are selected in order to ensure retention of the spacers in their proper positions, while providing a small clearance between the balls and spacers to avoid fluctuations or sharp increases in dynamic torque.

Abstract: A ball screw comprising a screw shaft 1 made of steel and having a thread groove 6 on outer peripheral surface, a ball nut 2 made of steel and having a thread groove 7 opposing the thread groove 6 on inner peripheral surface, a return tube 3 attached on the ball nut 2, and a plurality of balls inserted between the two thread grooves 6 and 7 and in the return tube 3. As the balls, steel balls 4 made of bearing steel and ceramic balls 5 made of silicon nitride are disposed alternately at a given ratio. Diameter Dc of the ceramic ball 5 is set to a value smaller than diameter Ds of the steel ball 4 so that contact stress acted on contact surfaces of the ceramic ball 5 and the two thread grooves 6 and 7 will be equal to contact stress acted on contact surfaces of the steel ball 4 and the two thread grooves 6 and 7.

Abstract: A ball screw device utilizes spacers having concave ball-contacting surfaces with distributed protrusions or dimples. Balls having needle-like recesses may also be used. The spacers are provided in two thicknesses, and the relative numbers of the thinner and thicker spacers are selected in order to ensure retention of the spacers in their proper positions, while providing a small clearance between the balls and spacers to avoid fluctuations or sharp increases in dynamic torque.

Abstract: A ball for a ball-point pen is provided comprising cemented carbide of WC—Cr3C2—Co where VC is contained as a solid solution in the Cr3C2—CO phase which is a binder of WC particles and wherein the mean diameter of the WC particles is in the range of from about 0.3 to about 0.5 &mgr;m. In one embodiment of the invention, a portion of the Cr3C2—VC—CO phase exposed on the surface of the ball comprises a plurality of concave recesses.

Abstract: A ball screw device utilizes spacers having concave ball-contacting surfaces with distributed protrusions or dimples. Balls having needle-like recesses may also be used. The spacers are provided in two thicknesses, and the relative numbers of the thinner and thicker spacers are selected in order to ensure retention of the spacers in their proper positions, while providing a small clearance between the balls and spacers to avoid fluctuations or sharp increases in dynamic torque.

Abstract: Spacers 26 each of which has a concave surface 27 complementary to the spherical surface of a ball 25 at each end thereof are disposed at areas between the adjacent balls 25, 25. A ball circulation mechanism comprises; a through hole 15 which extends in parallel to an axial line 4 of the ball nut 12 inside a thick wall part 14 of the ball nut 12; and adapters 23, 24 having open ends 23a, 24a provided with tongue portions 23c, 24c for scooping up or returning balls 25 between a ball screw groove 11 of a ball shaft 10 and a ball screw groove 13 of the ball nut 12, and the other open ends 23b, 24b being connected to be in communication with the through hole 15, and each adapter being fitted into recesses 16, 17 provided on both axial ends in the thick wall part 14 of the ball nut 12. Therefore, there is no need of upsizing a ball screw, and thus a compact ball screw which has a high load-carrying capacity and is suitable for a reciprocating movement can be provided.

Abstract: Spacers 10 of the same size are each disposed between adjacent ones of balls 6 which are loaded into each of endless circulation paths 8 formed in a carriage 3, and a spacer ball 12 having a diameter slightly smaller than a nominal diameter of each of the balls is disposed in a gap formed between the ball positioned at a start end as a start-end ball 6A and the ball positioned at a terminal end as a terminal-end ball 6B.Both axial end faces of each spacer 10 are formed as concave faces 20 conforming to the spherical surface of each ball 6 and thus there is no fear of disengagement of the spacers 10 and the balls 6 from each other during rolling of the balls.

Abstract: In order to provide a ball screw, ball, which allows to reduce the ball's noise and prevent wearing and clogging of ball s without decreasing its loading capacity, without using a ball chain or spacer balls, a cylindrical spacer 20 is disposed at each area between adjacent balls 10. The spacer 20 includes, at the both axial ends thereof, concave surfaces 22, 22, each of which is complementary to the spherical surface of the ball 10, and a crater-like oil pocket P is formed on the concave surfaces 22, 22 in order to retain a lubricant such as grease.The ball 10 slides in contact with the concave surfaces 22, 22. At that time, the lubricant reduces the friction of the ball 10, while the lubricant is transferred on the ball 10 and distributed over the ball circulation passage thoroughly.

Abstract: An apparatus for surface-hardening steel balls includes a container having projections protruding inwardly from and extending longitudinally along an inner wall; a support shaft having projections extending outwardly from and longitudinally along the support shaft; a container driving mechanism which rotates the container in one direction; and a support shaft driving mechanism which rotates the support shaft in an opposite direction. In operation, the container's projections transfer the balls from a lower portion of the container to a higher portion where the balls are dropped to the lower portion while the support shaft's projections strike the steel balls when the steel balls are dropping to the lower portion.