Gm Global Technolgoy Operations, Inc.

Thomson Saginaw Ball Screw Company, LLC

Robert L Benton

William E Welling

Dainis O Martinsons

Peter R Mugglestone

David A Lange

Flave F Stimpson

Joseph A Rutkiewicz

A ball nut and screw assembly has a ball screw mounting a nut assembly comprising a pair of ball nuts with the respective grooves of the screw and nut defining a pair of ball train accommodating axially spaced helical raceways. At least one preloading member is mounted between the nuts for imposing a preload on the raceways. External ball return tubes for each of the nuts communicate with opposite ends of each of the raceways for recirculating balls from one end of each raceway to the other. A unitary ball return tube clamp plate extends across the preloading member to clamp each of said ball return tubes to their respective nuts and fasteners extend between each of the nuts and the ends of the clamp plate for securing the return tubes in position while permitting the clamp plate to retain the nuts in preloaded condition.

Ball nut and screw assembly with preload retaining ball return tube clamp

A method of making ball screw and nut assemblies, and the products which result, wherein the nut is provided with a deformable wall portion of decreased compressive strength interjacent the ends of the nut. A compressive force is applied to the nut to axially deform the portion of decreased compressive strength while not changing the lead of adjacent lands and grooves in the non-compressed portion of the nut. The axial position of the lands and grooves in the non-compressed portion is thereby axially displaced such as to preload a recirculating train of balls traveling along the non-compressed portion of the nut relative to the lands and grooves of the screw, when the screw, nut, and balls are assembled.

Methods of making ball nuts for preloaded ball nut and screw assemblies

A ball nut and screw assembly has a conventional helical raceway and balls received therein that react load through the centerline of the assembly and an added helical raceway and balls received therein that react radial load on the ball nut to the relief of the first mentioned raceway and balls.

Ball nut and screw assemby with enhanced radial load capacity

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.

Seal and scraper assembly for ball bearing screws and the like

By using an existing ball nut and ball nut screw of a ball nut screw assembly as master models, imprint molds can be molded from a silicone rubber material which positively profiles the threading of the ball nut and ball nut screw with the crossover channel in the master model of the ball nut. A thermoset resin is added to the imprint molds and cured to form unitized all plastic ball nuts and ball nut screws with the helical grooving for accommodating the train of balls including the crossover channel in the ball nut molded therein to thereby provide an easily reproducable ball nut and screw assembly.

Method of molding a one piece plastic ball nut

A ball nut and screw assembly preadjusted and preloaded by injecting a liquefied pressurized thermoset resin through a mold and into the area between adjacent ball nuts and allowing the thermoset resin to cure and harden while pressurized. After hardening, the mold is removed and the external preload supplied to the resin is maintained by a hardened preload ring formed by the epoxy ring.

Preloaded ball nut and screw assembly and method of manufacture

A seal and scraper assembly for a nut and screw actuator has an elastomeric member bonded to a metal ring. The elastomeric member has an annular lip outer portion and a helical thread form inner portion. The inner portion has a plurality of scraper or wiper surfaces interrupting the thread form at an oblique angle and cooperating with a lubricant return surface to direct lubricant, scraped from the screw thread surface, into the housing enclosing the nut and screw actuator. A web portion extends between the outer lip and the inner thread form along the same angle as each scraper surface so that a component of the assembly forces on the outer lip portion are transmitted to the scraper surface so as to increase the thread sealing and scraping forces. The metal ring has a contoured inner surface which is effective to chip ice and other foreign matter from the screw thread outboard of the elastomeric member and a pair of radially extending lugs which cooperate with recesses formed in the nut to prevent relative rotation between the nut and the seal and scraper assembly.

Seal and scraper assembly

A ball nut and screw assembly is provided with a molded internal return system for a train of balls drivingly interconnecting the nut and screw. A ball nut with an internal crossover is used as a master mold to produce an imprint mold which positively profiles the helical groove and the cross of the master mold. The imprint mold is positioned in a blank nut and a thermal set resin is supplied to radial openings formed in the blank nut which subsequently hardens into a plug with an internal crossover channel like that of the master mold.

Ball nut with internal crossover for ball recirculation

Manufacture of ball nut with internal crossover path for ball

Ball nut and screw in which the nut has a ball pickup and return fixture on either end, each providing arcuately spaced ball pickup and returns to and from the spiraling lands associated with plural lead helical ball tracks of the screw. With plural lead ball tracks, increased ball nut travel with at least the same capacity as a single lead ball nut and screw is provided. The ball pickup and return fixtures have ramps and spiraled ball tunnels that provide for the smooth circulation of the separate ball trains of the system.

Plural lead ball nut screw actuator

Ball nut and screw are grooved to form helical race for an endless train of balls that circulate through the assembly. Leading and trailing turns of the race are connected by a return passage which includes an intermediate passage extending longitudinally of the nut. Special guide tracks in end sections of the ball nut have radially relieved paths, which allow high speed balls acted upon by centrifugal forces to travel along the outer surface thereof to avoid mechanical pick up to provide for smooth vibration-free linear movement of the ball nut along the rotating screw.

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Bay City, MI, United States of America

Robert L Benton