Lead screws are suitable and more cost-effective for low to medium loads. The screw shaft is a long cylindrical shaft that has a continuous groove, called the ball groove, that runs helically around the length of its shaft, which is referred to as the thread of the screw. The common groove profiles are the gothic arc and the circular arc: This is the most common groove profile. SANWA BUSINESS CREDIT CORPORATION 1 SOUTH WACKER, Free format text: UNITRON INCORPORATED, TEXAS, Free format text: The pitch refers to the distance of two consecutive threads, while the lead is the linear distance covered in one complete rotation. A threaded stem fixed to the deflector body secures the body to the nut, the stem being operative to maintain the body fixed relative to the nut by means of a conventional threaded fastener. The turn of the circuit refers to the number of trips the ball travels before being recirculated in the circuit. The accuracy of ball screws is improved by preloading, lubrication, and increasing the mounting accuracy. In spring preloading, a spring is placed between two ball nuts that transmit the preload. 3. They are used in medical equipment, food processing equipment, and laboratory machinery. 0000015939 00000 n In an internal ball recirculation system, the balls remain on the nut housing when they are recirculated. It is an important specification of a ball screw which determines linear travel and speed and load capacity. As the screw or nut rotates, the balls are deflected by the deflector into the ball return system of the nut and they travel through the return system to the opposite end of the ball nut in a continuous path. A ball deflector for a recirculating ball screw and nut assembly provides a plurality of adjustable semi-spherical locator bosses along an elongated body portion thereof for enhancing fitment of said deflector within a segment of the nut groove during assembly. 0000018305 00000 n 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. 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. 0000025842 00000 n 0000027562 00000 n 0000010128 00000 n The ball deflector of claim 7 wherein said bosses are semi-spherical, each having an initial unadjusted radius of approximately 0.100 inch. 0000010276 00000 n Deflector for ball screw and nut assembly, Assigned to BEAVER PRECISION PRODUCTS SUITE 3000, BEAVER PRECISION PRODUCTS SUITE 3000. To the extent that there is a slight offset between the two centers 68 and 70, the upper and lower body portions are symmetrically joined together by a portion having exterior contours which are tangent to the lower body 64. 0000034930 00000 n (a) The External Ball Return System. Chapter 5: Comparison of Ball Screws and Lead Screws. 1). During assembly, the bosses 60 are adjusted by an electric grinder or other metal removal means to assure satisfactory deflector alignment with the nut groove. The deflector body 32 contains bevelled ends 48 adapted to deflect each of the circulating train of balls 22 which pass through the mating grooves, so that the balls pass out of the nut and into the transfer tube though the apertures 24. For high speed or high load applications Barnes uses a tangential ball return system. Ball screws are classified according to their recirculation mechanism, the manufacturing method of the threads, and preload method. The ball recirculation mechanisms are grouped into internal recirculation and external recirculation systems. BEAVER AEROSPACE & DEFENSE, INC., MICHIGAN, Free format text: This value can vary from one lead to another. 0000023543 00000 n 0000003896 00000 n 9. The uncut blank shaft is passed through rotating tool dies to form the grooves. A substantial improvement would result if there were provided a mechanical means to alleviate or minimize such movement during fit-up of the deflector body within the nut groove. It is suitable for mass production and is more economic than internal recirculation systems. %PDF-1.6 % For every turn, there must be one deflector to close the pathway of the ball. The length of the return tube is supported by a tube holding bracket. 0000028484 00000 n BEAVER PRECISION PRODUCTS SUITE 3000, ILLINOIS, Free format text: Galling is common in threads of nuts and bolts, threaded fasteners, and threaded inserts, including ball screws. Therefore, the number of turns is always equal to the number of circuits for internal ball return systems. Ball screws typically have smaller motors because they consume less power than lead screws. J [KS{dIOG*OPL,d?'p? 0000005181 00000 n 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. 0000005487 00000 n ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DANA CORPORATION;REEL/FRAME:007251/0001, Owner name: Ball screws are more difficult to maintain than lead screws. The faults of the installed auxiliary components such as bearings, couplings, and nut brackets must be checked and corrected immediately to preserve the mounting accuracy. A major deficiency relates to the fit-up or fitment of such deflectors during assembly of the ball screw and nut assembly. They are used in precise positioning systems, in automotive steering systems, in electric vehicles, in energy-generating machinery such as wind turbines, solar panels, and hydroelectric equipment, in aircraft machinery, and as a viewing system for the photolithography process. Ball screws are a type of mechanical linear actuator. As Industry 4.0 and related initiatives continue to transform and advance the European market, NSK saw the need to develop and bring to market new deflector type ball screws, the most commonly used type in European machine tools. trailer Pitch is the axial distance between two adjacent threads. Meanwhile, lead screws are used for transfer applications where speed, accuracy, and precision are not of high priority. The ball deflector of claim 1 wherein said deflector body comprises two pairs of said locator bosses fixed to opposite sides of, and at opposite ends of, said elongated body. 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. Ball circle diameter (or pitch circle diameter) is the center-to-center distance of two opposite balls measured when the ball bearings are in contact with the grooves. 0000009264 00000 n However, the recirculation mechanism greatly affects the overall size of the ball screw. As will be appreciated, the adjustable bosses 60 offer a greater flexibility in accommodating tolerance variations. Oil and grease lubricants have a cooling effect. 2 will be treated as a single one of the three continuous or endless trains of balls 22. The ball screw will be available from January 2018, and NSK is targeting 1 billion yen global sales by 2020. The blank shaft is positioned horizontally, and an extremely hard abrasive cutter carves out the metal to form the grooves. The ball screw consists of a screw and nut with matching grooves and ball bearings that move between them. 2, while appearing to show one of the three loops, actually depicts partial views of two separate loops. Example (3): The Tangential Internal Ball Return System used by Barnes Industries. It can be prevented by preloading the ball screw. The upper and lower bodies 62 and 64 are symmetrically positioned with respect to each other. In the preferred embodiment of FIGS. The return tube assembly is easy to install and dismantle. In a preferred form, the ball deflector is mounted within the nut of a recirculating ball screw and nut assembly, the deflector having an elongate body adapted for cooperation with balls moving within a ball passage formed by a segment of cooperating helical grooves in the screw and nut. 0000026986 00000 n /Filter/FlateDecode>> Assigned to BEAVER AEROSPACE & DEFENSE, INC. Assignors: BEAVER PRECISION PRODUCTS, INC. 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. Referring initially to FIG. Ball screws are mechanical linear actuators that consist of a screw shaft and a nut that contain a ball that rolls between their matching helical grooves. ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:UNITRON INCORPORATED;REEL/FRAME:007251/0005, Owner name: 0000015877 00000 n However, these screws differ in many aspects. The arc in both profiles has slightly larger radii than the ball used. They are self-locking and do not require braking systems. Lead screws, like ball screws, serve a similar purpose to mechanical linear actuators that translate rotational motion to linear motion. It can disrupt the accuracy and repeatability, which are required for precise positioning applications. Since there are no spacers or springs required, it is more compact than double nut mechanisms. 0000003585 00000 n Having multiple starts solves the consequences of having high leads. 8. Ball screws generate more noise than lead screws. 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. To benefit from the lead accuracy a ball screw offers, it must have an accurate mounting. Multiple start screws are used when a rapid linear movement is for a lesser number of rotations and high load capacity screws. 6). Ball screws address the sliding friction generated by metal lead screws. The balls are usually made from steel. Single start screws are the most common. 0000025342 00000 n The start is the number of independent helices that run around the screw shaft. The ball deflector of claim 4 wherein each of said bosses lies on an angle of 10 to 25 degrees as measured from a line which passes through the center of the upper body, said line being orthogonal to said vertical centerline. 1. 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. It is a left-hand ball screw if the groove runs in a counterclockwise direction and it slants to the left. 0000000016 00000 n Ball screws may be categorized according to the mechanism of their ball recirculation. Thus, each deflector acts to provide a closed loop or circuit for each of the three passages in the nut. 0000026934 00000 n 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. 2 is taken. <>/ExtGState<>/Font<>/ProcSet[/PDF/Text]>>/Length 17 0 R PATENT RELEASE;ASSIGNOR:SANWA BUSINESS CREDIT CORPORATION;REEL/FRAME:008512/0367, Owner name: Deflectors, return tubes, and end caps are devices used to feed the ball back to its original position. Rolled screw threads are fabricated by a cold work deformation process. This design is ideal for high lead ball screw applications because it can endure the force from the fast-moving balls. FIG. 5 is a plan view of the preferred ball deflector of FIG. NSK will continue to develop and release market specific solutions under the slogan Your Real Partner" to meet the needs of customers worldwide. The ball deflector of claim 5 wherein said recirculating ball screw and nut assembly comprises a plurality of recirculating balls, and wherein said radius of said lower body portion comprises approximately 30% of said ball diameter. The key difference between ball screws and lead screws lies in their manner of transmitting loads. With a lead of 1 to 10 mm, these ball screws are well suited for machines and equipment that require precision small-pitch feeding and positioning. A major drawback with the aforedescribed approach, however, is in its fitment limitation to a singular groove-ball size. The deflector 50 incorporates an elongate body 52, wherein a threaded stem 54 is rigidly affixed to the body 52, preferably integral therewith. This design is used for applications that require fine leads. Each ball deflector 30 has an elongate body 32 retained within the mating helical grooves of the screw and nut. Though they appear to have more superior features than lead screws, lead screws find their worth in applications where they are deemed to be more cost-effective than ball screws. Example (2): The Internal Ball Return System used by Barnes Industries. Lubrication is necessary for ball screws to avoid thermal expansion and galling. In the cross-over deflector type of ball nuts, the balls make only one revolution of the shaft and the circuit is closed by a ball deflector (B) in the nut (C) allowing the ball to cross over between adjacent grooves at points (A) and (D). They require more frequent lubrication to stay in top condition. 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. 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. 1 from which FIG. The view depicted in FIG. Typically, such prior art nut would also include a flange (not shown) for providing actuation of a rod or coupling assembly mechanically fastened to the flange. 0000005814 00000 n Lead screws are also better in transmitting loads vertically. Meanwhile, ball screws need braking mechanisms to eliminate back driving. 0000004239 00000 n 0000015650 00000 n It is the minimum diameter of the screw shaft. The nut of a ball screw is a cylinder that houses the ball bearing and its recirculation system. In this type of screw, the lead is equivalent to the pitch. The radius R1 of the lower body 64 is approximately 30 percent of the ball diameter, while the radius R2 of the upper body 62 may range from approximately 35 to 50 percent of the ball diameter. The design of ball screws yields high accuracy during operation. visit our faq page for more information. The lead of a screw is equivalent to the number of starts multiplied by the pitch. % Xh@o?,zZf4DSPk2H 0'q:h=F K2"iCr"O jnG9qNJbB#*l5gMOk6. k$:f,!"T&&W=|f+L)jhE RfBnON6TijojzX8ghi/,B:#qL&"]eZp w\ETM5;Np!.ijrOC"H1{q4C%H A ball screw with a higher lead has a higher speed in operation but lower load capacity. 0000011201 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. End caps are mounted to guide the balls through a tunnel within the ball nuts internal; this directs them back to their starting point. The semi-circular arc profile is formed from a single arc, while the gothic arc profile has an ogival shape formed from two arcs. It has a compact size, which is suitable for small clearance assemblies. The friction acting on the ball screw component is the rolling friction, which is relatively smaller compared to sliding friction. However, this mechanism produces the smallest preload and is suitable in applications where precision is not that crucial. 0000025060 00000 n 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. The nut houses the ball bearings and their recirculation mechanism. 0000006142 00000 n The screw shaft is the component that receives the rotational force. When using, the screw shaft supported end may need additional machining in accordance with the conditions of use. * Claim based on an NSK review of currently available ball screw catalogues from major ball screw manufacturers. 0000006497 00000 n FIG. There are a variety of terms used to describe a linear actuator such as ram, piston, or activator IQS Directory This is called the critical speed and can be very detrimental to the life of a ball screw. %PDF-1.7 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. Screws typically have one, two, or four starts. PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362. BEAVER PRECISION PRODUCTS, INC., MICHIGAN, Free format text: You can serch for a ball screw by the combination of screw shaft diameter and lead. The balls pass through an external tube that is protruding from the ball nuts wall. <<247999CCFF4C954492059C9C96B9611E>]>> endstream endobj 433 0 obj<> endobj 434 0 obj<> endobj 435 0 obj<>/ColorSpace<>/Font<>/ProcSet[/PDF/Text]/ExtGState<>>> endobj 436 0 obj<> endobj 437 0 obj<> endobj 438 0 obj<> endobj 439 0 obj<> endobj 440 0 obj[/DeviceN[/DIC#202591p]/DeviceCMYK 491 0 R] endobj 441 0 obj[/Separation/DIC#202591p/DeviceCMYK 476 0 R] endobj 442 0 obj<> endobj 443 0 obj[/DeviceN[/DIC#202591p]/DeviceCMYK 494 0 R] endobj 444 0 obj[/DeviceN[/DIC#202591p]/DeviceCMYK 489 0 R] endobj 445 0 obj[/DeviceN[/DIC#202591p]/DeviceCMYK 484 0 R] endobj 446 0 obj[/DeviceN[/DIC#202591p]/DeviceCMYK 475 0 R] endobj 447 0 obj<> endobj 448 0 obj<> endobj 449 0 obj<> endobj 450 0 obj<> endobj 451 0 obj<> endobj 452 0 obj<>stream 0000005427 00000 n Power losses due to friction are one of the causes of low efficiency. The seal is a minor component of a ball screw that protects the entire ball screw assembly. 0000005548 00000 n Referring now to both FIGS. To this end, NSK has created a deflector type ball screw that boasts the highest* maximum feed speed in the world, and that conforms to German DIN industrial standards. 5pD5 K9,,'>Eoam(;/srzSaw[/ `;7>|h7O|=5OY[IKNtB7*jK?]0>kt>{0TeMCkw%9)O 0000024862 00000 n 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 lead error is the difference between the theoretical and actual distance that the nut has traveled when the screw shaft has rotated. NEW SIDE DEFLECTOR Method ball screws A series, GW series (Grade C7) / GY series (Grade C10), Slide screws with resin nuts PW series (Grade C10) / PY series (Grade C10), Customized product Ultra-quiet ball screws FR series, Custom Tube Method Ball Screws / GR Series, Laminated Precision Press Tools for Motor Core, Precision Metal Press Products / Motor Core, C0 to C7 grades(C0 to C5 grades for ball screws with integral nut). Please click here for Ball Screws technical information. 0000017074 00000 n The ball deflector of claim 3 wherein said upper body portion comprises a larger radius than that of said lower body portion, wherein centers of said radii are spaced apart along a vertical centerline passing through upper and lower extremities of said body. The two groove profiles differ on the contact points they touch on the ball. 0000005994 00000 n 4. Ball screws are made from materials with high rigidity and stiffness such as stainless steel. 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 bodies are generally semi-cylindrical, the upper body having a greater radius than the lower. This is where a rotating ball nut design is needed. As the lead of ball screws increases, the linear distance covered and the speed increase. 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. 0000006433 00000 n 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. This may be appreciated by those skilled in the art by reference to the cross section 2--2 of FIG. Ball screws produced using this method have high precision but are more expensive and are produced slowly. 0000003690 00000 n These are used in many applications across many industries. GVS:,AiBqE.9\y@mZ(\=[&u'tX. This clearance is unwanted because it causes backlash. y|@Ot99Qm)C`fpN S3OuKl6bUma*so+?eh02e1#[A\+kwE $M^b q;nPaB5 51hA!IWS11 esA;x:qVb;scZ0C?oV _>}dW!cVA& . $yzr] However, for convenience, the view of FIG. 2 0 obj The power to rotate the shaft is supplied by a motor, which is situated on its end. Linear Rails are ideal for moving items through a production process with great precision and as little friction as possible if creating, packing, and distributing products. To summarize, ball screws are valued for their power efficiency, accuracy, precision, and load capacity. Even more of a problem, however, is the fact that cumulative tolerance variations in deflector and nut groove sizing is such that rarely is there a satisfactory deflector fitment. The type of ball screw may also be distinguished according to its preloading method, which was discussed in the previous chapter. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). 0000009469 00000 n With this profile, the ball has one contact point on the screw shaft and one contact point on the nut. The screw shaft and the nut are directly moving against each other on Electric actuators are devices capable of creating motion of a load, or an action that requires a force like clamping, making use of an electric motor to create the force that is necessary A linear actuator is a means for converting rotational motion into push or pull linear motion, which can be used for lifting, dropping, sliding, or tilting of machines or materials. 5. Lead screws do not typically reach the torque conversion efficiencies of ball screws (around 90%). %`vQ@9Jy=,swSIue0'G%}'#s-GF\tde9NMJeU DpVXWq;@Mn>.}~q066#di(ZQ!agk3id:He.LS9b=o#`4eAPFM#cTgm I The screw shaft fixed end is finished to the type recommended by KURODA. 0000006054 00000 n The improved ball deflector of the present invention provides at least one pair of adjustable locator bosses, each of the pair disposed on adjacent upper quadrants of the circumference of the deflector body. ?/dpV[$;OHEb_ :D }~\ . Owner name: 0000009848 00000 n Preloading, lubrication, and increasing the mounting accuracy are techniques used to increase the lead accuracy of ball screws. Fingers are fixed on the endings of the return tube to guide the balls in entering and leaving the return tube. ;ASSIGNOR:SCHLENKER, THEODORE R.;REEL/FRAME:005248/0555, ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DANA CORPORATION;REEL/FRAME:007251/0001, BEAVER PRECISION PRODUCTS SUITE 3000, ILLINOIS, ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:UNITRON INCORPORATED;REEL/FRAME:007251/0005, SANWA BUSINESS CREDIT CORPORATION 1 SOUTH WACKER, SECURITY INTEREST;ASSIGNOR:BEAVER PRECISION PRODUCTS;REEL/FRAME:007251/0019, BEAVER PRECISION PRODUCTS, INC., MICHIGAN, PATENT RELEASE;ASSIGNOR:SANWA BUSINESS CREDIT CORPORATION;REEL/FRAME:008512/0367, BEAVER AEROSPACE & DEFENSE, INC., MICHIGAN, ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BEAVER PRECISION PRODUCTS, INC.;REEL/FRAME:008512/0558, PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362, Ball deflector for recirculating ball screw and nut assembly, Skirt deflector for a ball nut and screw device, Ball nut and method of manufacturing same, Ball screw lubricated with oil-containing polymer, Ball screw device having lubricating structure, Ball screw device and method of manufacturing the same, Ball screw device having circulating device, Ball screw device having circulating device background of the invention, Ball screw for machine tool, has extended part with passage aligned to inner winding of ball nut and to outer winding of screw shaft to receive ball bearing parts, where part of passage is formed in housing part and housing element, Ball recirculation tube and ball screw device, Ball screw nut ball prevention structure outside the circuit, Ball screw deflector and deflector ball screw, Ball deflector and screw cleaner for ball-bearing screw and nut assemblies, Ball deflector for ball screw and nut devices, Ball spline linear motion rolling guide unit, Ball return means for ball nut and screw means, Shaft supported linear motion guide system, Spindle drive assembly with recirculating balls, Radial / axial composite bearings with rolling elements, Arrangement for linear guidance of a machine element, Lapsed due to failure to pay maintenance fee, Patent reinstated due to the acceptance of a late maintenance fee, Lapse for failure to pay maintenance fees, Information on status: patent discontinuation.
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