Ball Screw Device and Dust-Proof Member Extracting Tool

{
  "publication_number": "US2014251049A1",
  "country": "US",
  "kind": "A1",
  "title": "Ball Screw Device and Dust-Proof Member Extracting Tool",
  "abstract": "A ball screw device is provided in which a dust-proof member can be simply attached to a nut. The ball screw device (1) is a ball screw device (1) in which a concave portion (6) is formed in an inner circumferential end portion of a nut (4) through which a screw shaft (2) passes and the concave portion (6) is provided with a dust-proof member (5), wherein the dust-proof member (5) is formed of a cylindrical elastic member into which the screw shaft (2) is inserted and includes at least one protrusion (8) protruding in an outward diameter direction from an outer circumferential surface of the dust-proof member (5), and the concave portion (6) has a groove shape to which the dust-proof member (5) is fitted and is provided with a locking portion (7) to which the protrusion (8) is locked.",
  "claims": [
    "1. A ball screw device in which a concave portion is formed in an inner circumferential end portion of a nut through which a screw shaft passes and the concave portion is provided with a dust-proof member, wherein the dust-proof member is formed of a cylindrical elastic member into which the screw shaft is inserted and includes at least one engagement piece protruding in an outward diameter direction from an outer circumferential surface of the dust-proof member, and wherein the concave portion has a groove shape to which the dust-proof member is fitted and is provided with a locking portion to which the engagement piece is locked. 2. The ball screw device according to claim 1, wherein an inclined face inclined to a central axis of the dust-proof member in the direction of the central axis is formed in the engagement piece. 3. The ball screw device according to claim 1, wherein the locking portion has a groove formed in the outward diameter direction in the concave portion. 4. The ball screw device according to claim 1, wherein the dust-proof member includes an arm portion made of an elastic member extending in the direction of the central axis, and wherein the engagement piece is disposed in the arm portion. 5. The ball screw device according to claim 4, wherein a cutout portion is formed in the outer circumferential surface of the dust-proof member, and wherein the arm portion is disposed in the cutout portion. 6. The ball screw device according to claim 4, wherein a distance between an outermost surface of the arm portion and the central axis when viewed in the direction of the central axis is larger than a radius of the outer circumferential surface of the dust-proof member. 7. The ball screw device according to claim 6, wherein the arm portion has a shape curved in the outward diameter direction. 8. The ball screw device according to claim 1, wherein the outer circumferential surface of the dust-proof member is provided with one or more groove portions in an axis direction and the protrusion is disengaged from the concave portion by pressing the inner wall of the groove portion toward the central axis by a protrusion of a tool. 9. The ball screw device according to claim 8, wherein the groove portions are disposed at regular intervals in the circumferential direction. 10. The ball screw device according to claim 1, wherein the outer circumferential surface of the dust-proof member is provided with a plurality of convex portions in an annular shape and in fragments being in contact with the inner circumferential surface of the nut. 11. The ball screw device according to claim 1, wherein an end face of the dust-proof member facing the nut in an insertion direction of the dust-proof member protrudes more in the insertion direction than the engagement piece protrudes. 12. A dust-proof member extracting tool having a cylindrical shape for extracting a dust-proof member of a ball screw device including a screw shaft, a nut disposed on an outer circumference of the screw shaft and having an engagement groove formed in a circumferential direction on the inner circumferential surface thereof with a predetermined distance from an end in an axis direction, a plurality of balls disposed between a spiral ball rolling groove formed on the outer circumferential surface of the screw shaft and a spiral ball rolling groove formed on the inner circumferential surface of the nut, and the dust-proof member having a cylindrical shape, having an engagement piece engaging with the engagement groove by elastic deformation formed on the outer circumferential surface thereof, being attached to the nut, and having one or more groove portions disposed in the axis direction on the outer circumferential surface, the dust-proof member extracting tool comprising: a first member which has an arc-like cross-sectional shape having a cutout larger than the diameter of the screw shaft and in which a plurality of protrusions for pressing an inner wall of the groove portion to the central axis to disengage the engagement piece from the engagement groove are disposed in an end portion to protrude in the axis direction; and a second member having an arc-like cross-sectional shape and being detachably attached to the first member in the circumferential direction to form the cylindrical shape. 13. The dust-proof member extracting tool according to claim 12, wherein an end portion of the second member is provided with one or more of the protrusions for pressing the inner wall of the groove portion to the central axis to disengage the engagement piece from the engagement groove to protrude in the axis direction. 14. The dust-proof member extracting tool according to claim 12, wherein the protrusions are disposed at regular intervals in the circumferential direction. 15. The ball screw device according to claim 2, wherein the locking portion has a groove formed in the outward diameter direction in the concave portion. 16. The ball screw device according to claim 5, wherein a distance between an outermost surface of the arm portion and the central axis when viewed in the direction of the central axis is larger than a radius of the outer circumferential surface of the dust-proof member. 17. The dust-proof member extracting tool according to claim 13, wherein the protrusions are disposed at regular intervals in the circumferential direction."
  ],
  "description_excerpt": "The present invention relates to a ball screw device used for, e.g. a steering apparatus, a heavy load carrying apparatus, a processing machine, a precise positioning apparatus, and the like and a dust-proof member extracting tool for extracting a dust-proof member disposed in the ball screw device.\n\nConventionally, a ball screw device is known which includes a dust-proof member for preventing intrusion of foreign materials such as dust, grit, and waste into a nut. As such a ball screw device, a ball screw device having a configuration in which attachment of a dust-proof member to a nut is carried out by fixing the dust-proof member with a fixing screw inserted from the outer circumference side of the nut is also known (for example, see PTL 1). In general, a ball screw device used as a mechanical element for converting rotational movement into straight movement includes a screw shaft and a cylindrical nut disposed on the outer circumference of the screw shaft, and plural balls are combined into a space between a spiral ball rolling groove formed on the outer circumferential surface of the screw shaft and a spiral ball rolling groove formed on the inner circumferential surface of the nut. In such a ball screw device, when foreign materials such as dust attached to the surface of the screw shaft intrudes into the nut, the smooth rolling movement of the balls is hindered and thus a dust-proof member in contact with the surface of the screw shaft is often attached to an end portion of the nut.",
  "cpc": [
    "F16H 25/2204",
    "B25B 27/0028",
    "B25B 27/28",
    "F16H 25/2418",
    "F16J 15/061",
    "F16J 15/3268",
    "Y10T 29/53657",
    "Y10T 74/19744"
  ],
  "ipc": [
    "B25B 27/28",
    "F16H 25/22"
  ],
  "assignees": [
    "NSK LTD"
  ],
  "inventors": [
    "KUROIWA DAISUKE"
  ],
  "filing_date": "2012-10-19",
  "publication_date": "2014-09-11",
  "priority_date": "2011-10-24",
  "application_number": "US-201214352347-A",
  "family_id": "48167413",
  "citations": [
    "US2006096397A1",
    "US4407511A",
    "US4905533A",
    "US6178839B1",
    "US6276225B1",
    "US6450295B1",
    "US6931955B2",
    "US7128199B2",
    "US7278333B2",
    "US8893570B2"
  ]
}