Example (1): Some manufacturers have one revolution circuits where the balls are forced to climb over the crest of the thread on the screw by the return system. The ball recirculation system in the nut allows the balls to be "recycled" in the operation by returning them to their starting point in the circuit. visit our faq page for more information. 0000024760 00000 n Lead screws are also better in transmitting loads vertically. Preload is applied by assembling larger ball bearings. 0000010364 00000 n %%EOF The assembly 10 includes an elongated screw 12 which has a continuous helical groove 14 delineated by a continuous helical land 16. Please click here for Ball Screws technical information. The auxiliary components supporting the ball screw must be mounted precisely to improve accuracy. ?/dpV[$;OHEb_ :D }~\ . mechanical kuroda screw ball suzin deflector method 1, a prior art recirculating ball screw and nut assembly 10 is shown fragmentarily. Ball screws produced using this method have high precision but are more expensive and are produced slowly. Ball screws are more difficult to maintain than lead screws. 0000006054 00000 n Ball screws are used for heavy-duty applications requiring high speed, high throughput, high accuracy, and long service times. We will discuss their important specifications and their impact on the operation. 8. 4 is an elevational view of a preferred embodiment of the ball deflector of the present invention. 0000004711 00000 n k$:f,!"T&&W=|f+L)jhE RfBnON6TijojzX8ghi/,B:#qL&"]eZp w\ETM5;Np!.ijrOC"H1{q4C%H The lead error is the difference between the theoretical and actual distance that the nut has traveled when the screw shaft has rotated. However, the surface produced is rough, which decreases the efficiency and wear resistance of the ball screw due to the higher friction it will encounter. At the ends of the body 52 are deflector ends 56 which function similarly to the ends 48 of the prior art version just described. PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362. The balls are usually made from steel. Even more of a problem, however, is the fact that cumulative tolerance variations in deflector and nut groove sizing is such that rarely is there a satisfactory deflector fitment. The radius of the upper body 62 emanates from an upper body center 68, while the lower body 64 radius emanates from the center 70. When tubes or caps are used to return the ball, they can be designed to create multiple independent circuits that are placed adjacent to each other. The ball is in contact with the screw shaft and the nut. ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DANA CORPORATION;REEL/FRAME:007251/0001, Owner name: 0000015877 00000 n Pitch is the axial distance between two adjacent threads. Ball screws typically have smaller motors because they consume less power than lead screws. The ball screw consists of a screw and nut with matching grooves and ball bearings that move between them. It is suitable for mass production and is more economic than internal recirculation systems. Power losses due to friction are one of the causes of low efficiency. The uncut blank shaft is passed through rotating tool dies to form the grooves. DANA CORPORATION, OHIO, Free format text: A large preload requires more torque and can cause excessive heat generation. This is called the critical speed and can be very detrimental to the life of a ball screw. The nominal diameter is the maximum diameter of the screw shaft excluding the ball bearings. Backlash is the lost motion caused by the clearance between the ball and the nut and screw tracks. Ball screw and nut assemblies include deflectors for the purpose of ensuring efficiency of ball transfer between return tubes and associated ball passages formed by helical grooves provided in the screw and nut. It preserves the efficiency of the ball screw by keeping contaminants and foreign materials from entering the clearance between the ball and the nut; it also retains the lubrication of the ball screw assembly. The ball groove serves as the pathway for the rolling ball bearings. In an external ball recirculation system, the ball traverses outside the nut housing when it is recirculated. NSK Ltd. (NSK; Headquarters: Tokyo, Japan; President and CEO: Toshihiro Uchiyama) today announced it has developed a new high-speed, low-noise deflector type ball screw tailored for European machine tool applications. As is typical of the latter construction, the lower body portion 40 is formed to provide greater clearance from the sides of the mating groove 14 of the screw for accommodating axial and radial movement or lash in the screw relative to the nut to avoid binding of the screw on the deflector member. In a ball deflector for a recirculating ball screw and nut assembly, said deflector including an elongate body adapted for placement within a ball passage formed by a segment of cooperating helical grooves in a screw and a nut, said nut being movable along said screw, said deflector defining a body, a stem fixed to said body and adapted for securement of said body to said nut, said stem operative to maintain said body fixed relative to said nut; an improvement comprising said body including at least a pair of adjustable locator bosses disposed for engaging the groove of the nut, each boss disposed in adjacent quadrants on the circumference of said body. SECURITY INTEREST;ASSIGNOR:BEAVER PRECISION PRODUCTS;REEL/FRAME:007251/0019, Owner name: Still some applications require longer shaft lengths and high speeds. Circuit refers to the closed path in the recirculating system of the ball nut. 0000015819 00000 n Its operation relies on the sliding of the screw shaft and the nut threads with no ball bearings between them. In the assembly 10 as shown, three such tubes 26 are utilized, hence there are three trains of bearing balls adapted for circulation through the cooperating grooves between the screw and nut. The ball bearings, or the balls, are the most prominent component of the ball screws that moves between the clearance of the nut and the shaft. 0000024483 00000 n 2 is a cross sectional view along lines 2--2 of FIG. Since there are no external protrusions, ball nuts with this return system are more compact. Referring to FIGS. Continuous rubbing of the metal components with poor lubrication causes galling, a form of abrasive wear that causes tearing of the metal surface at the microscopic level. This is a very durable ball return system and is also used on high load carrying applications. It is an important specification of a ball screw which determines linear travel and speed and load capacity. PATENT RELEASE;ASSIGNOR:SANWA BUSINESS CREDIT CORPORATION;REEL/FRAME:008512/0367, Owner name: The design of ball screws yields high accuracy during operation. 5. Assigned to SANWA BUSINESS CREDIT CORPORATION 1 SOUTH WACKER, SANWA BUSINESS CREDIT CORPORATION 1 SOUTH WACKER. Lead screws are available in polymeric materials coated with materials with self-lubricating properties such as polytetrafluoroethylene (PTFE), silicone, and graphite; these generate less friction. Consequently, upon tightening the threaded fastener 36 on the stem 34 during assembly, the elongate body 32 is often rotated about the axis a--a of the stem, resulting in deflector ends 48 which are not aligned with the nut groove. However, the improved deflector 50 incorporates pairs of adjustable locator bosses 60 situated at opposite ends of the body 52 and in close proximity to the ends 56. 2.

In an internal ball recirculation system, the balls remain on the nut housing when they are recirculated. There are a variety of terms used to describe a linear actuator such as ram, piston, or activator IQS Directory 0000012373 00000 n

In this type of return system, the ball is returned to the opposite end of the circuit through a ball return tube which protrudes above the outside diameter of the ball nut. 0000006562 00000 n 0000027562 00000 n Ball screws may be categorized according to the mechanism of their ball recirculation. Fingers are fixed on the endings of the return tube to guide the balls in entering and leaving the return tube. The balls 22 traverse a helical path within the mating grooves, and a plurality of transfer tubes 26 are arranged to provide a like plurality of endless groups (called trains) of circulating balls which loop through the nut and transfer tubes. The balls pass through an external tube that is protruding from the ball nuts wall. 0000004239 00000 n 0000005994 00000 n 3, the body 32 of the prior art deflector 30 is more fully shown in its operative environment between nut and screw grooves 20 and 14, respectively. The relationship between the turn and the circuit depends on the recirculation method of a ball screw. y|@Ot99Qm)C`fpN S3OuKl6bUma*so+?eh02e1#[A\+kwE $M^b q;nPaB5 51hA!IWS11 esA;x:qVb;scZ0C?oV _>}dW!cVA& . $yzr] The two groove profiles differ on the contact points they touch on the ball. FIG. The seal is a minor component of a ball screw that protects the entire ball screw assembly.

Their differences are enumerated in this chapter, as well as the pros and cons of each type. ball equipped ballscrews For every turn, there must be one deflector to close the pathway of the ball. SANWA BUSINESS CREDIT CORPORATION 1 SOUTH WACKER, Free format text: 1 and 2, it will be apparent that four ball deflectors 30 are employed (FIG. The start is the number of independent threads that run around the screw shaft. A lead screw is a kind of mechanical linear actuator that converts rotational motion into linear motion. Copyright KURODA Precision Industries Ltd. All Rights Reserved. Standard Ground Ball Screws / DP Series: Accuracy grade C3. 0000003585 00000 n Call today! <>/ExtGState<>/Font<>/ProcSet[/PDF/Text]>>/Length 17 0 R ;ASSIGNOR:SCHLENKER, THEODORE R.;REEL/FRAME:005248/0555, Owner name: The balls then exit from the ball return system into the ball screw and nut thread raceways continuously to recirculate in a closed circuit. NEWSIDE DEFLECTOR Ball Screw AD Series, NEWSIDE DEFLECTOR Ball Screw AH Series. 0000009360 00000 n The ball recirculation mechanisms are grouped into internal recirculation and external recirculation systems. 0000026934 00000 n The deflector 50 incorporates an elongate body 52, wherein a threaded stem 54 is rigidly affixed to the body 52, preferably integral therewith. The start is the number of independent helices that run around the screw shaft. The arc in both profiles has slightly larger radii than the ball used. Tensional forces are applied on two adjacent sides of the ball nuts due to the spring force. 4. Ball screws are made from materials with high rigidity and stiffness such as stainless steel. MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING, ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL, Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms, Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions, Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members, Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls, Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls with elements for guiding the circulating balls, GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS, TECHNICAL SUBJECTS COVERED BY FORMER USPC, TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION, ASSIGNMENT OF ASSIGNORS INTEREST. Ball screws address the sliding friction generated by metal lead screws. The return tube directs the balls back to their starting point. 0000027056 00000 n A highly accurate and precise ball screw has a minimal lead error. Those skilled in the art will appreciate the long standing practice of attempting to fit an elongate body of a deflector into a nut groove so as to cause the latter to be symmetrically seated and aligned within the screw groove. The ratio of the number of threads in the ball nut circuit to the number of threads on the ball screw determines how much sooner the ball nut will reach fatigue failure (wear out) than the ball screw will.

NSK will continue to develop and release market specific solutions under the slogan Your Real Partner" to meet the needs of customers worldwide. The nut houses the ball bearings and their recirculation mechanism. Screws typically have one, two, or four starts. Referring initially to FIG. Each ball deflector 30 has an elongate body 32 retained within the mating helical grooves of the screw and nut. The industrys smallest nut dimensions were achieved by using an improved ball circulation system called deflector method, which allows for minimal nut dimensions. The screw shaft fixed end is finished to the type recommended by KURODA. The blank shaft is positioned horizontally, and an extremely hard abrasive cutter carves out the metal to form the grooves. 7. 6 which depicts a cross section of the body 52 taken through a pair of the bosses 60, those skilled in the art will appreciate that an upper body portion 62 is adapted to be seated in the prior art nut groove 20, while the lower body 64 is adapted to be received in the groove -4 of a conventional screw.

They are more customizable than ball screws. 0000005181 00000 n With this design, clearance between the ball and the ball or nut is inevitable. 4, 5, and 6, a preferred embodiment of the deflector 50 of the present invention is now shown and described. 0000001676 00000 n The ball deflector of claim 9 comprising a solid precision cast member. 0000016389 00000 n During securement of the stem to the nut by means of threaded fasteners, manufacturing tolerances tend to give rise to an objectionable amount of cocking or shifting (about the stem axis) of the deflector body within the groove. The groove surface produced is smoother than the rolled screw. NSK develops high-speed, low-noise deflector type ball screw for European machine tool applications. Ball screws are a type of mechanical linear actuator. 0000013741 00000 n BEAVER PRECISION PRODUCTS SUITE 3000, ILLINOIS, Free format text: To download data, CADENAS WEB2CAD,Inc. The main components of ball screws are the screw shaft, the nut, and the ball bearings (or balls). The oversized balls produce a more compact structure by increasing the contact area of the balls to the grooves. Ball screws have a higher load capacity than lead screws. 6). 0000006142 00000 n The screw shaft and the nut are directly moving against each other on Electric actuators are devices capable of creating motion of a load, or an action that requires a force like clamping, making use of an electric motor to create the force that is necessary A linear actuator is a means for converting rotational motion into push or pull linear motion, which can be used for lifting, dropping, sliding, or tilting of machines or materials. 0000010032 00000 n Linear slides, also referred to as linear guides or linear-motion bearings, are types of bearings that allow smooth and near-frictionless motion in a single axis. This mechanism significantly lessens the friction generated, which results in highly efficient power conversion. +7W.~\c]0:8rA@'%uvi=(PGx1W(\9x6 W3l'g =]J+m`f3[ .tkbM }V:5x>[j(J4( 0T$f%a=@P97]DX,4)]2[O: Although only one preferred embodiment has been detailed and described herewith, the following claims envision numerous additional embodiments which are not shown or described herein. The ball deflector of claim 2 wherein said deflector body comprises integral upper and lower body portions, each portion defining a generally semi-cylindrical member, wherein said bosses are located on the quadrants defined by said upper body portion. The unique element of ball screws is the rolling balls in the helical groove which reduces the mechanical contact inside the screw assembly and replaces sliding friction with rolling friction. 0000026986 00000 n The unique element of ball screws is the ball bearings, which increase the power efficiency by minimizing the friction during the movement of the ball and nut. 0000005814 00000 n 0000005427 00000 n This groove profile has the shape of a semicircle. 5 is a plan view of the preferred ball deflector of FIG. It avoids the premature breakdown of the ball screw and increases its performance by lowering the coefficient of friction and by minimizing the heat build-up resulting from the motion of the ball screw components. Deflectors, return tubes, and end caps are devices used to feed the ball back to its original position. The large plastic deformation of the blank results in a high strength screw shaft. The two deflectors located at the opposite ends of the nut 18 each employs only one of its two bevelled ends 48, as will be appreciated by those skilled in the art. End caps are mounted to guide the balls through a tunnel within the ball nuts internal; this directs them back to their starting point. xref 0000005874 00000 n 0000010128 00000 n Lead screws do not typically reach the torque conversion efficiencies of ball screws (around 90%). 0000008936 00000 n Ball screws have higher efficiency, speed, accuracy, and load capacity, making them useful in a wide range of industrial applications. %PDF-1.7

;)Q $EIa|?]h` z2B;|oFX\}B*V/Z#gCkA-L[XH} d[j QpP{RpPgeyygOD M P' N v]AM?s z) This is where a rotating ball nut design is needed. 0000026251 00000 n

The relative height of the body 52 as measured between the upper extremity 66 and lower extremity 67 along vertical centerline b--b is approximately 95% of the diameter of a selected ball size.

startxref For high speed or high load applications Barnes uses a tangential ball return system. Lead screws have simpler and more compact designs than ball screws. 0000009848 00000 n ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BEAVER PRECISION PRODUCTS, INC.;REEL/FRAME:008512/0558, Free format text: The turn is the number of trips that a ball travels before being recirculated.

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