Seal and scraper assembly for ball bearing screws and the like
AssigneeThomson Saginaw Ball Screw Company, Inc.
InventorsRobert L. Benton, Dainis O. Martinsons
Life of this patent
Estimating the term…
Abstract
A seal and scraper assembly for a ball screw and nut actuator has a resilient seal ring for reception by the nut which includes a radially internal helical thread mating with the screw groove. The seal ring further has a radially compressible annular lip extending at an angle in an axially outboard direction from the outer periphery of the ring to engage and be radially compressed by the nut. A rigid, annular mount ring also has an internal thread received by the screw groove which has an axially inboard portion interfitting with the seal ring so as to permit relative axial movement of the seal ring and mount ring, while preventing relative rotation of the rings.
Claims14
A ball screw and nut assembly comprising:
- a. an axially extending screw having an external helical thread and a ball receiving helical groove for the reception of a series of balls;
- b. a nut, having an internal helical groove, bounded by seal and scraper assembly receiving end surface portions, received on said screw;
- c. said helical grooves of the screw and nut forming a raceway;
- d. balls received in said raceway permitting relative rotation and translation of said nut and screw with relatively low frictional impedance;
- e. a non-rigid, resilient, annular seal ring housed by said nut in said receiving portion at each end of the nut and having an axially inboard section and an axially outboard section;
- f. said inboard section including a radially internal helical thread projection received by and mating with said screw groove;
- g. said inboard section further having a radially compressible lip integrated with its outer periphery and extending at an acute angle from said outer periphery in an axially outboard direction to engage and be radially compressed by said nut;
- h. a comparatively rigid, annular mount ring at each end of the nut, at least partly outboard of the seal ring, and having an axially inboard portion interfitting with said seal ring, the mount ring and seal ring having interfitting parts permitting relative axial movement of the seal ring and mount ring;
- i. the mount ring also having a radially internal thread received by and mating with said screw groove;
- and
- j. the mount ring and nut having parts preventing the mount ring in said receiving surface portions of the nut at each end of the nut from rotating relatively.
In a seal and scraper assembly for a ball screw and nut actuator having an axially extending screw with an external helical thread and a ball receiving groove, and a nut, having an internal helical groove bounded at least at one end by a seal and scraper assembly receiving end surface portion, received on said screw, with said grooves of the screw and nut forming a raceway for balls permitting relative rotation and translation of said nut and screw with relatively low frictional impedance:
- a. a non-rigid, resilient, annular seal ring for reception by said nut in said receiving portion at at least one end of the nut and having an axially inboard section and an axially outboard section;
- b. said inboard section including a radially internal helical threaded projection received by and mating with said screw groove;
- c. said inboard section further having a radially compressible lip integrated with its outer periphery and extending at an acute angle from said outer periphery in an axially outboard direction to engage and be radially compressed by said nut;
- d. a comparatively rigid, annular mount ring at each end of the nut having an axially inboard portion integrated with said seal ring to prevent relative rotation between the rings;
- e. the mount ring also having a radially internal thread received by and mating with said screw groove;
- and
- f. the mount ring having parts cooperable with said nut for preventing relative rotation of the nut and mount ring.
In a seal and scraper assembly for a ball screw and nut assembly having an axially extending screw with an external helical thread and a ball receiving groove, and a nut, having an internal helical groove, bounded by at least one seal and scraper assembly receiving end surface portion, received on said screw, with said grooves of the screw and nut forming a raceway for balls permitting relative rotation and translation of said nut and screw with relatively low frictional impedance:
- a. a non-rigid, resilient, annular seal ring for reception by said nut in said receiving portion at at least one end of the nut and having an axially inboard section and an axially outboard section;
- b. said inboard section including a radially internal helical thread projection received by and mating with said screw groove;
- c. a comparatively rigid, annular mount ring at at least one end of the nut having a radially internal thread projection received by and mating with said screw groove, the mounting ring also having an axially inboard portion interfitting with said seal ring, the mount ring and seal ring having interfitting means preventing relative rotation of the rings while permitting some relative axial floating movement of the seal ring and mount ring to achieve independent seating of the thread projection of each in the screw groove;
- and
- d. the mount ring having parts cooperable with the nut for preventing relative rotation of the nut and mount ring.
A method of sealing the threads of a ball screw and nut assembly having an axially extending screw with an external helical groove, and a nut with an internal helical groove bounded by a thread seal receiving end surface portion which is received on the screw, with the helical grooves of the screw and nut forming a raceway for balls permitting relative rotation and translation of the nut and screw, with relatively low frictional impedance, and wherein a resilient seal ring has an inboard section with a radially internal helical thread adapted to be received by the screw groove, and is provided with a rigid mount ring with a radially internal thread adapted also to be received by the screw groove, the mount ring and seal ring having interfitting parts capable of preventing their relative rotation while permitting relative axial movement of the rings, the steps of:
- a. axially relatively moving the seal ring and mount ring to interfit the interfitting parts thereof to form an assembly;
- b. relatively moving an interfitted seal ring and mount ring, and a nut, axially to position the seal ring and mount ring in said receiving end surface portion of the nut and restrain relative rotation of the nut and assembly;
- c. relatively rotating the nut and screw to thread the screw into the nut, and the seal ring and mount ring;
- and
- d. relatively axially moving the seal ring and mount ring to permit each to adjust independently to the helical configuration of the screw groove.
Dependencies are inferred from the claim text.