0000026251 00000 n
Power losses due to friction are one of the causes of low efficiency. For instance, in double-start screws, the lead is equivalent twice its pitch; this means that the axial distance covered is two-pitch units for one full rotation completed by the screw. ;ASSIGNOR:SCHLENKER, THEODORE R.;REEL/FRAME:005248/0555, Owner name: <<247999CCFF4C954492059C9C96B9611E>]>>
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. Owner name: 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. This clearance is unwanted because it causes backlash. Example (3): The Tangential Internal Ball Return System used by Barnes Industries. The ball screw assembly consists of a screw and a nut, each with matching helical grooves, and balls which roll between these grooves providing the only contact between the nut and the screw. This article presents all the information you need to know about ball screws. 0000024483 00000 n
However, this mechanism produces the smallest preload and is suitable in applications where precision is not that crucial. NEWSIDE DEFLECTOR Ball Screw AD Series, NEWSIDE DEFLECTOR Ball Screw AH Series. The pitch and lead are two related specifications of ball screws. A lead screw is a kind of mechanical linear actuator that converts rotational motion into linear motion. The nut of a ball screw is a cylinder that houses the ball bearing and its recirculation system. website require registration. The safe operating speed should not exceed 80% of the critical speed for the screw. 0000009469 00000 n
Heat causes the thermal expansion of the components and negatively affects the accuracy of the ball screw. During machining, to create the grooves, an offset is created in the lead, which is in the middle of a recirculation circuit. Angles A are formed by the intersection of lines c--c and d--d which pass through the left boss 60, (located left of the vertical centerline b--b), and by the intersection of lines c-c and ee, the latter of which passes through the center of the right boss 60 (located on the right side of line b--b). 0000005181 00000 n
Rolled screw threads are fabricated by a cold work deformation process. However, for convenience, the view of FIG. 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. 
They make up the component dedicated to reducing the friction generated by the nut and the moving screw; this friction would be too great if the balls were not present in the screw assembly. Lead screws are also better in transmitting loads vertically. 0000025342 00000 n
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. 0000011201 00000 n
Assigned to BEAVER AEROSPACE & DEFENSE, INC. Assignors: BEAVER PRECISION PRODUCTS, INC. Circuit refers to the closed path in the recirculating system of the ball nut. The spacer applies force on the adjacent sides of two ball nuts; this force is transmitted to the nut and the grooves. The deflector 50 incorporates an elongate body 52, wherein a threaded stem 54 is rigidly affixed to the body 52, preferably integral therewith. It has a compact size, which is suitable for small clearance assemblies. Screws typically have one, two, or four starts. Root diameter is the distance between the bottommost section of the groove to the bottommost section of the opposite groove. FIG. An integral ball deflector stem 34 has an exterior threaded surface which receives a conventional threaded fastener 36 for retaining each deflector 30 rigidly within the groove 20 of the nut 18. The ball groove serves as the pathway for the rolling ball bearings. In spring preloading, a spring is placed between two ball nuts that transmit the preload. The return tube assembly is easy to install and dismantle. 4. trailer
8. The ball deflector of claim 7 wherein said bosses are semi-spherical, each having an initial unadjusted radius of approximately 0.100 inch. 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. 0000012373 00000 n
Since there are no external protrusions, ball nuts with this return system are more compact. 1 and 2, it will be apparent that four ball deflectors 30 are employed (FIG. 0000009360 00000 n
Ball screws have higher efficiency, speed, accuracy, and load capacity, making them useful in a wide range of industrial applications. 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. This solves the consequences of using higher leads. 0000023441 00000 n
0000008936 00000 n
visit our faq page for more information. FIG. 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. 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. 0000006054 00000 n
0000009264 00000 n
The ball screw consists of a screw and nut with matching grooves and ball bearings that move between them. <>/ExtGState<>/Font<>/ProcSet[/PDF/Text]>>/Length 17 0 R 0000017074 00000 n
0000010032 00000 n
500 0 obj<>stream
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. 0000035021 00000 n
They are used in medical equipment, food processing equipment, and laboratory machinery. SECURITY INTEREST;ASSIGNOR:BEAVER PRECISION PRODUCTS;REEL/FRAME:007251/0019, Owner name: This mechanism significantly lessens the friction generated, which results in highly efficient power conversion. As a result, the working action of the deflector is compromised and maximum efficiency or smoothness in circulation of the balls is inhibited. The bosses are disposed on adjacent quadrants of the upper half of the elongate body and are adapted for seating the body within the groove of the nut during assembly. 6). Lubrication is important in ball screws. 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. Please click here for KURODA Selection Guide for Ball Screws. In a preferred form, the deflector body has two pairs of the locator bosses fixed to opposite sides of, and opposite ends of, the elongate deflector body. They are self-locking and do not require braking systems. As the lead of ball screws increases, the linear distance covered and the speed increase. 0000004239 00000 n
The accuracy of ball screws is improved by preloading, lubrication, and increasing the mounting accuracy. BEAVER AEROSPACE & DEFENSE, INC., MICHIGAN, Free format text: SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). To benefit from the lead accuracy a ball screw offers, it must have an accurate mounting. 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. 0000005934 00000 n
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. Ideally, the bosses are symmetrically positioned on the upper body in a manner such that the two equal angles A equal 10 to 25 degrees (FIG. 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. 
With this profile, the ball has one contact point on the screw shaft and one contact point on the nut. It is important to optimize the preload value in ball screws and maintain it during the operation. 0000025842 00000 n
A traveling nut 18 is adapted to move axially along the screw, the nut defining an interior mating helical groove 20. The ball is in contact with the screw shaft and the nut. 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. Preload is applied by assembling larger ball bearings. Backlash is the lost motion caused by the clearance between the ball and the nut and screw tracks. 0000025060 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. The ball screw will be available from January 2018, and NSK is targeting 1 billion yen global sales by 2020. 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. The screw shaft is the component that receives the rotational force. 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. This is called the critical speed and can be very detrimental to the life of a ball screw. %%EOF
The key difference between ball screws and lead screws lies in their manner of transmitting loads. 0000009848 00000 n
The circuit is the number of closed paths in a recirculation system. 0000026177 00000 n
This is known as a cross-over deflector type internal return system. A ball screw with a higher lead has a higher speed in operation but lower load capacity. The ball deflector of claim 8 wherein said deflector stem is integrally attached to said deflector body. 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. The balls pass through an external tube that is protruding from the ball nuts wall. It is dependent on the manufacturing accuracy of the ball grooves, compactness, and set-up precision of the assembly. It is accomplished by using a spacer or a spring between two nuts, by using oversized balls, or by offsetting a lead. An inherent problem in such fit-up relates to cumulative manufacturing tolerances. It can be prevented by preloading the ball screw. xViPv%%iwE C] uQHRDl `LR7VqnJsrNX9?wF>^ ` ,f,7Q_>@ #@{*vY=A.s--tM7__=v}K}1u_bJIo65^{qS0[8K1$nxln|&=85X)t]Q}{[_7H`*@hegwO#3Q*o]&] NNnDP'5zp3,(w5hMZ}|'fsqQul6:xBF6FMnW$9N!=v=$I\" 3xYfat|p"s2F8('z!+{}?&#rK*8C@>H;wiQ"~sT\-w].[/Yyf^G>_Um A%O2A*2T'[j5uz]Sv|xj0=?s&lr2gy=+}AR2mI`J(~!&&QH!g]T)1FkXF@']l:vXp=KB Each ball deflector 30 has an elongate body 32 retained within the mating helical grooves of the screw and nut. 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. 0000006142 00000 n
With this design, clearance between the ball and the ball or nut is inevitable. 
Meanwhile, lead screws are used for transfer applications where speed, accuracy, and precision are not of high priority. Copyright KURODA Precision Industries Ltd. All Rights Reserved. The oversized balls produce a more compact structure by increasing the contact area of the balls to the grooves. The view depicted in FIG. 0000026986 00000 n
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. All Rights Reserved. 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. NSK has long manufactured ball screws to meet the demanding requirements of customers, mainly in the Japanese machine tool market, including the High-speed, Low-noise Series and other high performance ball screws. The main components of ball screws are the screw shaft, the nut, and the ball bearings (or balls). SANWA BUSINESS CREDIT CORPORATION 1 SOUTH WACKER, Free format text: 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. Referring now to FIG. 0000028484 00000 n
It is a long cylindrical body that contains ball grooves. This may be appreciated by those skilled in the art by reference to the cross section 2--2 of FIG. The seal is a minor component of a ball screw that protects the entire ball screw assembly. %`vQ@9Jy=,swSIue0'G%}'#s-GF\tde9NMJeU
DpVXWq;@Mn>.}~q066#di(ZQ!agk3id:He.LS9b=o#`4eAPFM#cTgm I When using, the screw shaft supported end may need additional machining in accordance with the conditions of use. 0000009557 00000 n
FIG. 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. 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 have a higher load capacity than lead screws. Another classification of ball screws is according to the fabrication method of producing the ball grooves: Ground screw threads are fabricated by an abrasion process. They are capable of carrying heavier loads than single circuit ball nuts. Ball screws are a type of mechanical linear actuator. xref
Single start screws are the most common. Preloading is the application of axial force on the balls and the grooves of the screw shaft and the nut to make them compact. 10. ASSIGNMENT OF ASSIGNORS INTEREST. 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. Ball screws are made from materials with high rigidity and stiffness such as stainless steel. The two groove profiles differ on the contact points they touch on the ball. 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. 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). 3 is a cross sectional view along lines 3--3 of FIG. Deflectors, return tubes, and end caps are devices used to feed the ball back to its original position. You can serch for a ball screw by the combination of screw shaft diameter and lead. 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. Referring to FIGS. 5. 0000005874 00000 n
?/dpV[$;OHEb_ :D }~\ . 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 bosses are adjusted by a grinder to accommodate tolerance variations encountered during assembly. This is a very durable ball return system and is also used on high load carrying applications. More particularly, the invention relates to an improved ball deflector employed in such assemblies. This value can vary from one lead to another. Preloading, lubrication, and increasing the mounting accuracy are techniques used to increase the lead accuracy of ball screws. 0000010364 00000 n
The start is the number of independent threads that run around the screw shaft. 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. Lead screws have simpler and more compact designs than ball screws. Multiple start screws are used when a rapid linear movement is for a lesser number of rotations and high load capacity screws. 0000008149 00000 n
1 from which FIG. Call today! Lead screws have deeper helical threads in the screw shaft and a matching nut that slides with each other. 432 69
The bodies are generally semi-cylindrical, the upper body having a greater radius than the lower. The preloading mechanism dictates if the ball screw has a single or double ball nut. 0000014841 00000 n
NSK will continue to develop and release market specific solutions under the slogan Your Real Partner" to meet the needs of customers worldwide. 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. HW]T9}_!BS40+"( =:~O4>=>RVoQ'R+nB OBOo? xuxc,Q,duh>Cm)Irzq&j[H4GC{q#Mu/mV[l&h]6
BS*7^'u^=zL+uk
8:L13!C [W:+Nfm\ayt#6;EQOWFY2qut" {6>gMTJWEZ3X[>)\V)7Sr Mp ,8TYSI"Ho8!NQ)1}8 4. Ball screws address the sliding friction generated by metal lead screws. 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. 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. Ball screws are used for heavy-duty applications requiring high speed, high throughput, high accuracy, and long service times. A major deficiency relates to the fit-up or fitment of such deflectors during assembly of the ball screw and nut assembly. They are more customizable than ball screws. It is an important specification of a ball screw which determines linear travel and speed and load capacity. However, the recirculation mechanism greatly affects the overall size of the ball screw. 
0000024760 00000 n
Mounting is how the ball screw is supported during its operation. The balls are usually made from steel. 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). The arc in both profiles has slightly larger radii than the ball used. Referring initially to FIG. Example (2): The Internal Ball Return System used by Barnes Industries. Oil and grease lubricants have a cooling effect. It is made by two intersecting arcs. A large preload requires more torque and can cause excessive heat generation. 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 ball recirculation mechanisms are grouped into internal recirculation and external recirculation systems. 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. The ball groove profile of a ball screw may either be a semi-circular arc or a gothic arc. 0000005303 00000 n
0000026934 00000 n
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. 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. 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. 4, 5, and 6, a preferred embodiment of the deflector 50 of the present invention is now shown and described. BEAVER PRECISION PRODUCTS SUITE 3000, ILLINOIS, Free format text: We will discuss their important specifications and their impact on the operation. 0000016389 00000 n
ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BEAVER PRECISION PRODUCTS, INC.;REEL/FRAME:008512/0558, Free format text: Preloading is the application of force to compact the ball screw structure to avoid backlash. 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. Ball screws generate more noise than lead screws. 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. Fingers are fixed on the endings of the return tube to guide the balls in entering and leaving the return tube. The use of lead screws is a more cost-effective option for low to medium loads and applications where accuracy and load capacity are not major concerns. The upper and lower bodies 62 and 64 are symmetrically positioned with respect to each other. When a long ball screw rotates at high speed it can begin to vibrate once the slenderness ratio reaches the natural harmonics for that shaft size. %PDF-1.6
%
Ball screws may be categorized according to the mechanism of their ball recirculation. 0000010216 00000 n
3. The preloading mechanisms commonly utilized in ball screw assemblies are as follows: In spacer preloading, a spacer is inserted between two ball nuts to achieve the desired preload. It is the minimum diameter of the screw shaft. Machine tools, robots, actuators, sensors, and other mechanical equipment often require moving components in a straight line in any of the three-dimensional axes A linear actuator actuates, moves, in a linear, straight, line to complete or start a process. PATENT RELEASE;ASSIGNOR:SANWA BUSINESS CREDIT CORPORATION;REEL/FRAME:008512/0367, Owner name: 2 is taken. GVS:,AiBqE.9\y@mZ(\=[&u'tX. Ball screws are classified according to their recirculation mechanism, the manufacturing method of the threads, and preload method. 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. 
Galling is common in threads of nuts and bolts, threaded fasteners, and threaded inserts, including ball screws. Referring now to FIG. 0000005487 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. Inaccurate mounting causes noise, vibration, positioning errors, and may cause material failure and accelerated wear during continuous operation. 0000027056 00000 n
Let us assist you in engineering your machine tool for a rotating ball nut design. Pitch is the axial distance between two adjacent threads. 0
0000006667 00000 n
This provides a very smooth flow of balls at any speed in a limited amount of space. The ball deflector of claim 6 wherein said radius of said upper body comprises approximately 35 to 50% of said ball diameter. 0000000016 00000 n
The uncut blank shaft is passed through rotating tool dies to form the grooves. The screw shaft is the component of the ball screw that receives rotational force for it to rotate about its axis; this is translated to linear motion. To download data, CADENAS WEB2CAD,Inc. The groove surface produced is smoother than the rolled screw. 2 0 obj 0000035124 00000 n
The balls then exit from the ball return system into the ball screw and nut thread raceways continuously to recirculate in a closed circuit. Standard Ground Ball Screws / DP Series: Accuracy grade C3. ;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.
They make up the component dedicated to reducing the friction generated by the nut and the moving screw; this friction would be too great if the balls were not present in the screw assembly. Lead screws are also better in transmitting loads vertically. 0000025342 00000 n
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. 0000011201 00000 n
Assigned to BEAVER AEROSPACE & DEFENSE, INC. Assignors: BEAVER PRECISION PRODUCTS, INC. Circuit refers to the closed path in the recirculating system of the ball nut. The spacer applies force on the adjacent sides of two ball nuts; this force is transmitted to the nut and the grooves. The deflector 50 incorporates an elongate body 52, wherein a threaded stem 54 is rigidly affixed to the body 52, preferably integral therewith. It has a compact size, which is suitable for small clearance assemblies. Screws typically have one, two, or four starts. Root diameter is the distance between the bottommost section of the groove to the bottommost section of the opposite groove. FIG. An integral ball deflector stem 34 has an exterior threaded surface which receives a conventional threaded fastener 36 for retaining each deflector 30 rigidly within the groove 20 of the nut 18. The ball groove serves as the pathway for the rolling ball bearings. In spring preloading, a spring is placed between two ball nuts that transmit the preload. The return tube assembly is easy to install and dismantle. 4. trailer
8. The ball deflector of claim 7 wherein said bosses are semi-spherical, each having an initial unadjusted radius of approximately 0.100 inch. 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. 0000012373 00000 n
Since there are no external protrusions, ball nuts with this return system are more compact. 1 and 2, it will be apparent that four ball deflectors 30 are employed (FIG. 0000009360 00000 n
Ball screws have higher efficiency, speed, accuracy, and load capacity, making them useful in a wide range of industrial applications. 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. This solves the consequences of using higher leads. 0000023441 00000 n
0000008936 00000 n
visit our faq page for more information. FIG. 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. 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. 0000006054 00000 n
0000009264 00000 n
The ball screw consists of a screw and nut with matching grooves and ball bearings that move between them. <>/ExtGState<>/Font<>/ProcSet[/PDF/Text]>>/Length 17 0 R 0000017074 00000 n
0000010032 00000 n
500 0 obj<>stream
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. 0000035021 00000 n
They are used in medical equipment, food processing equipment, and laboratory machinery. SECURITY INTEREST;ASSIGNOR:BEAVER PRECISION PRODUCTS;REEL/FRAME:007251/0019, Owner name: This mechanism significantly lessens the friction generated, which results in highly efficient power conversion. As a result, the working action of the deflector is compromised and maximum efficiency or smoothness in circulation of the balls is inhibited. The bosses are disposed on adjacent quadrants of the upper half of the elongate body and are adapted for seating the body within the groove of the nut during assembly. 6). Lubrication is important in ball screws. 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. Please click here for KURODA Selection Guide for Ball Screws. In a preferred form, the deflector body has two pairs of the locator bosses fixed to opposite sides of, and opposite ends of, the elongate deflector body. They are self-locking and do not require braking systems. As the lead of ball screws increases, the linear distance covered and the speed increase. 0000004239 00000 n
The accuracy of ball screws is improved by preloading, lubrication, and increasing the mounting accuracy. BEAVER AEROSPACE & DEFENSE, INC., MICHIGAN, Free format text: SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). To benefit from the lead accuracy a ball screw offers, it must have an accurate mounting. 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. 0000005934 00000 n
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. Ideally, the bosses are symmetrically positioned on the upper body in a manner such that the two equal angles A equal 10 to 25 degrees (FIG. 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. With this profile, the ball has one contact point on the screw shaft and one contact point on the nut. It is important to optimize the preload value in ball screws and maintain it during the operation. 0000025842 00000 n
A traveling nut 18 is adapted to move axially along the screw, the nut defining an interior mating helical groove 20. The ball is in contact with the screw shaft and the nut. 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. Preload is applied by assembling larger ball bearings. Backlash is the lost motion caused by the clearance between the ball and the nut and screw tracks. 0000025060 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. The ball screw will be available from January 2018, and NSK is targeting 1 billion yen global sales by 2020. 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. The screw shaft is the component that receives the rotational force. 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. This is called the critical speed and can be very detrimental to the life of a ball screw. %%EOF
The key difference between ball screws and lead screws lies in their manner of transmitting loads. 0000009848 00000 n
The circuit is the number of closed paths in a recirculation system. 0000026177 00000 n
This is known as a cross-over deflector type internal return system. A ball screw with a higher lead has a higher speed in operation but lower load capacity. The ball deflector of claim 8 wherein said deflector stem is integrally attached to said deflector body. 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. The balls pass through an external tube that is protruding from the ball nuts wall. It is dependent on the manufacturing accuracy of the ball grooves, compactness, and set-up precision of the assembly. It is accomplished by using a spacer or a spring between two nuts, by using oversized balls, or by offsetting a lead. An inherent problem in such fit-up relates to cumulative manufacturing tolerances. It can be prevented by preloading the ball screw. xViPv%%iwE C] uQHRDl `LR7VqnJsrNX9?wF>^ ` ,f,7Q_>@ #@{*vY=A.s--tM7__=v}K}1u_bJIo65^{qS0[8K1$nxln|&=85X)t]Q}{[_7H`*@hegwO#3Q*o]&] NNnDP'5zp3,(w5hMZ}|'fsqQul6:xBF6FMnW$9N!=v=$I\" 3xYfat|p"s2F8('z!+{}?&#rK*8C@>H;wiQ"~sT\-w].[/Yyf^G>_Um A%O2A*2T'[j5uz]Sv|xj0=?s&lr2gy=+}AR2mI`J(~!&&QH!g]T)1FkXF@']l:vXp=KB Each ball deflector 30 has an elongate body 32 retained within the mating helical grooves of the screw and nut. 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. 0000006142 00000 n
With this design, clearance between the ball and the ball or nut is inevitable. Meanwhile, lead screws are used for transfer applications where speed, accuracy, and precision are not of high priority. Copyright KURODA Precision Industries Ltd. All Rights Reserved. The oversized balls produce a more compact structure by increasing the contact area of the balls to the grooves. The view depicted in FIG. 0000026986 00000 n
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. All Rights Reserved. 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. NSK has long manufactured ball screws to meet the demanding requirements of customers, mainly in the Japanese machine tool market, including the High-speed, Low-noise Series and other high performance ball screws. The main components of ball screws are the screw shaft, the nut, and the ball bearings (or balls). SANWA BUSINESS CREDIT CORPORATION 1 SOUTH WACKER, Free format text: 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. Referring now to FIG. 0000028484 00000 n
It is a long cylindrical body that contains ball grooves. This may be appreciated by those skilled in the art by reference to the cross section 2--2 of FIG. The seal is a minor component of a ball screw that protects the entire ball screw assembly. %`vQ@9Jy=,swSIue0'G%}'#s-GF\tde9NMJeU
DpVXWq;@Mn>.}~q066#di(ZQ!agk3id:He.LS9b=o#`4eAPFM#cTgm I When using, the screw shaft supported end may need additional machining in accordance with the conditions of use. 0000009557 00000 n
FIG. 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. 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 have a higher load capacity than lead screws. Another classification of ball screws is according to the fabrication method of producing the ball grooves: Ground screw threads are fabricated by an abrasion process. They are capable of carrying heavier loads than single circuit ball nuts. Ball screws are a type of mechanical linear actuator. xref
Single start screws are the most common. Preloading is the application of axial force on the balls and the grooves of the screw shaft and the nut to make them compact. 10. ASSIGNMENT OF ASSIGNORS INTEREST. 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. Ball screws are made from materials with high rigidity and stiffness such as stainless steel. The two groove profiles differ on the contact points they touch on the ball. 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. 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). 3 is a cross sectional view along lines 3--3 of FIG. Deflectors, return tubes, and end caps are devices used to feed the ball back to its original position. You can serch for a ball screw by the combination of screw shaft diameter and lead. 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. Referring to FIGS. 5. 0000005874 00000 n
?/dpV[$;OHEb_ :D }~\ . 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 bosses are adjusted by a grinder to accommodate tolerance variations encountered during assembly. This is a very durable ball return system and is also used on high load carrying applications. More particularly, the invention relates to an improved ball deflector employed in such assemblies. This value can vary from one lead to another. Preloading, lubrication, and increasing the mounting accuracy are techniques used to increase the lead accuracy of ball screws. 0000010364 00000 n
The start is the number of independent threads that run around the screw shaft. 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. Lead screws have simpler and more compact designs than ball screws. Multiple start screws are used when a rapid linear movement is for a lesser number of rotations and high load capacity screws. 0000008149 00000 n
1 from which FIG. Call today! Lead screws have deeper helical threads in the screw shaft and a matching nut that slides with each other. 432 69
The bodies are generally semi-cylindrical, the upper body having a greater radius than the lower. The preloading mechanism dictates if the ball screw has a single or double ball nut. 0000014841 00000 n
NSK will continue to develop and release market specific solutions under the slogan Your Real Partner" to meet the needs of customers worldwide. 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. HW]T9}_!BS40+"( =:~O4>=>RVoQ'R+nB OBOo? xuxc,Q,duh>Cm)Irzq&j[H4GC{q#Mu/mV[l&h]6
BS*7^'u^=zL+uk
8:L13!C [W:+Nfm\ayt#6;EQOWFY2qut" {6>gMTJWEZ3X[>)\V)7Sr Mp ,8TYSI"Ho8!NQ)1}8 4. Ball screws address the sliding friction generated by metal lead screws. 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. 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. Ball screws are used for heavy-duty applications requiring high speed, high throughput, high accuracy, and long service times. A major deficiency relates to the fit-up or fitment of such deflectors during assembly of the ball screw and nut assembly. They are more customizable than ball screws. It is an important specification of a ball screw which determines linear travel and speed and load capacity. However, the recirculation mechanism greatly affects the overall size of the ball screw. 0000024760 00000 n
Mounting is how the ball screw is supported during its operation. The balls are usually made from steel. 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). The arc in both profiles has slightly larger radii than the ball used. Referring initially to FIG. Example (2): The Internal Ball Return System used by Barnes Industries. Oil and grease lubricants have a cooling effect. It is made by two intersecting arcs. A large preload requires more torque and can cause excessive heat generation. 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 ball recirculation mechanisms are grouped into internal recirculation and external recirculation systems. 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. The ball groove profile of a ball screw may either be a semi-circular arc or a gothic arc. 0000005303 00000 n
0000026934 00000 n
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. 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. 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. 4, 5, and 6, a preferred embodiment of the deflector 50 of the present invention is now shown and described. BEAVER PRECISION PRODUCTS SUITE 3000, ILLINOIS, Free format text: We will discuss their important specifications and their impact on the operation. 0000016389 00000 n
ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:BEAVER PRECISION PRODUCTS, INC.;REEL/FRAME:008512/0558, Free format text: Preloading is the application of force to compact the ball screw structure to avoid backlash. 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. Ball screws generate more noise than lead screws. 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. Fingers are fixed on the endings of the return tube to guide the balls in entering and leaving the return tube. The use of lead screws is a more cost-effective option for low to medium loads and applications where accuracy and load capacity are not major concerns. The upper and lower bodies 62 and 64 are symmetrically positioned with respect to each other. When a long ball screw rotates at high speed it can begin to vibrate once the slenderness ratio reaches the natural harmonics for that shaft size. %PDF-1.6
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Ball screws may be categorized according to the mechanism of their ball recirculation. 0000010216 00000 n
3. The preloading mechanisms commonly utilized in ball screw assemblies are as follows: In spacer preloading, a spacer is inserted between two ball nuts to achieve the desired preload. It is the minimum diameter of the screw shaft. Machine tools, robots, actuators, sensors, and other mechanical equipment often require moving components in a straight line in any of the three-dimensional axes A linear actuator actuates, moves, in a linear, straight, line to complete or start a process. PATENT RELEASE;ASSIGNOR:SANWA BUSINESS CREDIT CORPORATION;REEL/FRAME:008512/0367, Owner name: 2 is taken. GVS:,AiBqE.9\y@mZ(\=[&u'tX. Ball screws are classified according to their recirculation mechanism, the manufacturing method of the threads, and preload method. 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. Galling is common in threads of nuts and bolts, threaded fasteners, and threaded inserts, including ball screws. Referring now to FIG. 0000005487 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. Inaccurate mounting causes noise, vibration, positioning errors, and may cause material failure and accelerated wear during continuous operation. 0000027056 00000 n
Let us assist you in engineering your machine tool for a rotating ball nut design. Pitch is the axial distance between two adjacent threads. 0
0000006667 00000 n
This provides a very smooth flow of balls at any speed in a limited amount of space. The ball deflector of claim 6 wherein said radius of said upper body comprises approximately 35 to 50% of said ball diameter. 0000000016 00000 n
The uncut blank shaft is passed through rotating tool dies to form the grooves. The screw shaft is the component of the ball screw that receives rotational force for it to rotate about its axis; this is translated to linear motion. To download data, CADENAS WEB2CAD,Inc. The groove surface produced is smoother than the rolled screw. 2 0 obj 0000035124 00000 n
The balls then exit from the ball return system into the ball screw and nut thread raceways continuously to recirculate in a closed circuit. Standard Ground Ball Screws / DP Series: Accuracy grade C3. ;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.