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TIC is also the leading player in the market for Universal Cylindrical Grinding Machines in particular, both manual and NC type, with each holding 60% of domestic market share from the early 2000’s. Our machines are well recognized for excellent quality which our customers and users attribute to our expertise in assembly skills and use of high quality ballscrew components. Please let us know what way we could be of service to your company in providing quality ball screws.

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- 6. Main Product Items TSF Type (No preload) TFP Type (Integrally Preloaded ) TFN Type TFF Type (Tube Type, Flange, Single-nut) (Tube Type, Flange, Single-nut) (Tube Type, Flange, Double-nut) (Tube Type, Flange-to-Flange, Double-nut) DSF Type (No preload) DFP Type (Integrally Preloaded) DFN Type DFF Type (Deflector Type, Flange, Single-nut) (Deflector Type, Flange, Single-nut) (Deflector Type, Flange, Double-nut) (Deflector Type, Flange-to-Flange, Double-nut) LTF Type (No preload) LTP Type (Preloaded with Oversize Balls) YEF Type (Preloaded with Oversize Balls) LEF Type (No Preroad) (Tube Type, Flange, Single-nut) (Tube Type, Flange, Single-nut) (Endcap Type, Flange, Single-nut) (Endcap Type, Flange, Single-nut) TBSF Type TNSF Type TMS Type TRS Type (Tube Built-in Flange nut) (Outer Diameter small Flange nut) (Triangle Screw Type nut) (Square Shape nut)8
- 7. Equipment System High-tech equipment system of TIC produces the best ball screw with high technical skills Quality SystemTorque Measuring instrument Shaft Laser Measuring InstrumentShaft proportional Measuring instrument NUT Form Measuring Instrument MainProduction EquipmentIn order to keep the whole temperature and humidityconstantly in the main production line, 4 thermo-hygrostats are automatically operated, thereforethe production of the goods with high precision isavailable minimizing the error due to difference oftemperature and humidity such as bending underthe process, change of length, etc.. Shaft Cylindrical Grinding Machine (Kondo)Shaft Thread External Grinding Machine (Mitsuisiki) NUT Thread Internal Grinding Machine (Matrix) 9
- 8. Equipment System Quality Assurance Facilities Ball screw total tester This tester helps to solve the precision and noise problems which happen to ball screws and analyze the problems through computers to find out the causes of defects. It is an important piece of testing equipment which TIC has developed on its own. This is a device to secure customers’ reliability by improving feeding accuracy of NC machine tools measuring the rigidity of ball screws in axial direction and conducting optimum design to minimize displacement by cutting forces. How to read the measured data rigidity tester Upper limit Base line Actual value Average-Range Lower limit Rigidity displacement sensor10
- 9. Introducing new Ball Screw High-speed Low-Noise Ball Screws (YEF Type) Contribution to comfortable environment First step toward production of low-noise machines and equipmentFeatures- Low noise and good sound quality achieved improved ball circulation structure (Structure to reduce ball impulsive sound)- Noise reduction achieved by change of material (Adoption of material with low impulsive sound)- Higher precision of ball track shape (Improvement in track shape and surface roughress) - Written in Page 113 -Construction Performance Noise comparison between conventional and new products Shaft diameter Lead Steel diameter Lubricants No. of winding Noise Assessment distance screw and ball between microphone Noise reduction effectiveness increasesCirculation in tangential directions as the speed increases Comparison Products New Products Rotation speed of shaftCirculation in lead angle directions 11
- 10. Introducing new Ball Screw High speed ball screw with caged Low noise, Low torque friction Long-term, maintenace free operation Features - Low noise and anacceptable running sound - The use of ball cage reducing the fluctuation in dyramic torque, thus to achieve smooth motion - Grease pockets to be achieving long-term mainte nance-free operation Construction Circulation in tangential directions Circulation in lead angle directions Circulation in tangential directions Circulation in lead angle directions Performance Preload torque Preload torque Conventional products Standard products New products Preload torque Features 1. Noise reduction effectiveness increases as the speed increases. 2. About 6 dB less than the conventional tube. (3,500 RPM) Retainer applied products comparative circulation of friction torque noise test data12
- 11. Introducing new Ball Screw High-speed Precision Ball with Air Cooling sustemActions against thermal displacement by frictionLow friction/low heat dissipation structureFeatures Cooling data- Built-in shaft/unit air cooling mechanis mand Test Conditions high-precision feed with minimal environmental impact- Low noise and good sound quality achieved improved T.P. Model no. T.P. Model no. ball circulation structure (Structure to reduce ball impulsive sound) Shaft diameter Shaft diameter- Higher precision of ball track shape Lead (Improvement in track shape and surface roughness) Lead- Maximum feed speed : 60mm/min Number of coils windings Number of coils windings Max-speed Max-speed Max-acceleration Max-acceleration Weight of moving part Weight of moving part Temperature increase data (Measuring position : nut) General products General products Air cooling products Air cooling products Coil and air Coil and air filled products filled products Time TimeConstructionAir cooling structure 13
- 12. TIC Precision Ball Screws : Types, Series, and Construction Table 1.1 TIC Precision Ball Sc rews : Types, Series, and Construction Series Construction 1. T Series A tube is provided in the nut. Steel balls, rolling in the grooves between the shaft and nut, (Tube type : external enter the tube and roll down. They then return to the groove between the shaft and nut. ball circulation) This series fits the widest variety of applications among the series, and is suitable for standard manufacture. The nut outer diameter is determined such that the components through which balls circulate (tube and holder) cannot move beyond the nut circumference. The nut outer diameter which is smaller then tube and holder position is also available on request. Deflectors are provided inside the nut. Steel balls, rolling 2. D Series Deflectors are provided inside the nut. Steel balls, rolling in the grooves between the shaft (Deflector type : internal and nut, move along the grooves of deflector. They then return to the groove between the shaft and nut, passing through the shaft ball circulation) groove rand. Since steel balls circulate inside the nut, the nut outer diameter can be small. The deflectors are placed at equally spaced on the nut outside surface, so the nut can retain good balance. 3. L Series The L series is characterized by a large lead. Precise nut positioning is possible at high speed. They can be classified into the tube type and end cap type, according to the (Tube type) steel ball circulation system. 4. E Series It is characterized by high speeds and clean and clear sounds through smooth rotation (Endcap type) by making the rotation direction of the steel ball consistent with the lead angle. It is also possible to make the same rigidity of products with the internal circulation type and compact structure, which is 30% more compact than conventional products. 5. R Series R series represent form rolling ball screw and the type use a tube type. Tube inserting method can be divided into 4 kinds including a dumping type where (Rolling Ball Screw) insert completely into nut outer diameter and a projecting type where project to outside14
- 13. TIC Precision Ball Screws :Types, Series, and Construction Type Page TFN Type(Flange, Double-nut) TSF Type(No preload, Flange, Single-nut) TFP Type(Preload, Flange, Single-nut) TFF Type(Flange-to-flange, Double-nut) TNN Type(No flange, Double-nut) TSN Type(No preload, Single-nut) TPN Type(Preload, Single-nut) YTF Type(Preloaded with Oversize Balls) DFN Type(Flange, Double-nut) DSF Type(No preload, Flange, Single-nut) DFP Type(Preload, Flange, Single-nut) DFF Type(Flange-to-flange, Double-nut) DNN Type(No flange, Double-nut) DSN Type(No preload, Single-nut) DPN Type(Preload, Single-nut) YDF Type(Preloaded with oversize balls) LTF Type(Tube type, No preload, Flange) LTP Type(Tube type, Preload, Flange) YEF Type(Preloaded with Oversize Balls) H-ESH Type(No preload) TBSF Type(Tube Built-in Flange Nut) TNSF Type(Outer Diameter Small Flange Nut) TMS Type(Triangle Screw Type Nut) TRS Type(Square Shape Nut) 15
- 14. TIC Precision Ball Screw Features High transfer efficency. * Ball screws, unlike slide screws, produce extremely low friction. They achieve high transfer efficiency, while maintaining running torque at one-third that of slide screws. Great thrust load can be obtained at small torque. Figs. 2.1 and 2.2 show ball screw transfer efficiency. Ball screws convert rotary motion into linear motion in normal use, but can also be used to convert linear motion into rotary motion(reverse action). Fine travel capabilities. * 1 The rolling contract of ball screws contributes 1 = extremely low starting friction. They do not produce 2 1 any stick slip, to which slide screws are liable. Where, Ball screws can be controlled precisely is a fine travel. 1 : Input torque 1 : Output thrust : Lead, mm 1 : Efficiency in normal action High rigidity with preload. High rigidity can be achieved by using a preload with two nuts, or by using a preload with oversize Fig. 2.1 Mechanical Efficiency of Precision Ball balls in single nut, which eliminates axial clearance. Screws(Normal Action) Long service life.* Steel balls roll on heat-treated or hardened grooves is extremely low, and high precision can be maintained over a long period of time. Service life can be estimated by calculation. Easy maintenance.* Unlike slide screws, ball screws do not require frequent lubrication. Under normal operating conditions, they operate satisfactorily with an occasional supply of grease or lubrication oil. High reliability * The relationship between input and output can be TIC precision ball Screws are highly reliable, expressed by equation 2.2 below. produced at plants where temperature is strictly 2 2 controlled. They are controlled under an integrated 2 = 2 quality control system, which governs material, production equipment, production and inspection. Where, 2 : Input torque 2 : Output thrust : Lead, mm 2 : Efficiency in active action The relationship between input and output can be Fig. 2.2 Mechanical Efficiency of Precision Ball expressed by equation 2.1 below. Screws(Reverse Action)16
- 15. TIC Precision Ball Screw SpecificationsLead tolerances *TIC precision ball screw tolerances (class 5 and above) are established according to Japanese Industrial Standards(JIS).The lead tolerances are defined in Fig. 3.1. Fig. 3.1 Definition of Cumulative Lead Error TermsLead Precision Terms *1) Basic lead. 6) Variation The lead used as basic. The width of the cumulative actual lead variation. It is It is normally the same as the nominal lead. However, obtained by drawing two lines, one of which runs on a modified value may intentionally be used depending the peak of the variation on the upper side of the on the purpose. cumulative actual lead curve, and the other, on the lower side of the curve. The two lines should be2) Cumulative basic lead(Cumulative lead target value). parallel to the representative lead line. The value obtained by deducting the cumulative lead : Maximum width for the entire effective threaded of the effective threaded portion length from the basic portion length. lead(Cumulative nominal lead). 3 00 : Maximum width for a 300-mm range optionally To make relevant compensation in case of shaft elastic designated in the effective threaded portion deformation due to external loads or in case of length. deformation due to temperature variation, ball screws 2 : Maximum width of difference between an actually may be produced to a cumulative basic lead that may measured axial lead and the basic lead for an either be larger or smaller than the basic lead. optionally designated rotation angle. The angle should be designated not to exceed3) Cumulative actual lead. one entire turn of the shaft. The cumulative lead is obtained by measuring at an optionally selected cross section which includes the Refernce * shaft axis. The cumulative lead error for general-purpose ball4) Cumulative representative lead. screws C7 and C10 is determined solely depending on tolerances for a 300mm range optionally designated A straight line that represents the tendency of within the effective threaded portion length. cumulative leads. This is obtained by approximating the cumulative actual lead curve by the method of least square or by Class Cumulative Lead Error, similar approximation method.5) Cumulative representative lead error. The value obtained by deducting the cumulative basic lead from the cumulative representative lead. 17
- 16. TIC Precision Ball Screw Specifications Table3.1 Cumulative Cumulative Representateiv Lead Errors and Allowable Variation Values Unit : Effective Threaded Tolerance Class Portion Length Cumulative Cumulative Cumulative Cumulative Cumulative O v e rI ncl representative Variation representative Variation representative Variation representative Variation representative Variation lead error lead error lead error lead error lead error Table3.2 Tolearnces of Variation for 300mm in the Eefcftiev Threaded Portion Length ( ) and Variation for 2 rad ( ) Unit : Tolerance Class Item Axial Clearance * Table 3.3 Available Combination of Axial Clearance Size and Thread Tolerance Unit : Axial Clearance Tolerance Class preloaded Up to Up to Up to Up to - - - - - - - - -18
- 17. TIC Precision Ball Screw SpecificationsRegular combinations of shaft outer Material and heat treatment *diameter and lead * The hardness of groove surfaces is critical for ballTable 3.4 shows regular combinations of the shaft screw service life. TIC uses materials and heatouter diameter and lead. For products of other treatments listed in Table 3.5 below to achievespecifications, please consult TIC. appropriate hardness.Table 3.4 Standard Combinations of Shaft Outer Diameter and Lead Table 3.5 Precision Ball Screw Materials and Heat Unit : TreatmentsShaft OuterDiameter Lead Shaft Nut For use in special environments, e.g., in a corrosive environment or in a vacuum, ball screws made from special material, such as stainless steel(e.g.SUS440C), are also available on request. Please consult TIC.P roducible range in overall shaft length *Fig. 3.2 shows the producible range of precision ballscrews in terms of overall shaft length. For thoseexceeding the shown ranges or extra small ballscrews, please consult TIC. Fig. 3.2 Producible Range in Overall Shaft Length 19
- 18. TIC Precision Ball Screw Specifications 3.5. The balls are in contact with the grooves Preload engineering and preload torque * between the nut and shaft at four points, when preload the ball screw. This method is Ball screws normally have a slight clearance called preload with oversize balls. between steel balls and groove surfaces. If no clearance is provided, backlash occurs due to elastic displacement caused by axial loads. To prevent this, ball screws are preloaded, i.e., axial loads are applied, giving elastic displacement to steel balls and groove surfaces and eliminating axial clearance, while enhancing rigidity. 1) Preloading systems (a) Spacer preloading system A spacer is Fig. 3.5 Preload With Oversize Balls provided between two nuts, when preloading the ball screw. There are two methods in this In the second method, nut is grinded by shifting system . the screw lead at middle point, as shown in One is to provide a thick spacer between two Fig. 3.6 to produce an appropriate preload. nuts to apply an appropriate size of preload to This is called integral preload . the ball screw(Fig. 3.3). This method is called tensile preload. Fig. 3.6 Integral Preload Fig. 3.3 Tensile Preload. The other is to provide a thin spacer between (c) Constant preloading system two nuts to apply an appropriate size of preload to the ball screw(Fig. 3.4). This method is called This system uses two nuts, between compression preload. which a spring is provided, to give a specified size of preload to the ball screw. This system can keep torque variation low. Fig. 3.4 Compression Preload (b) Single-nut preloading system This method uses a single nut to preload the Fig. 3.7 Constant Preload ball screw. There are two methods. One method uses steel balls which are slightly larger than the ball grooves, as shown in Fig.20
- 19. TIC Precision Ball Screw Specifications2) Effects of preload The relationship between ball screw axial load and elastic displacement can be expressed as ( : constant), according to Hertz s theory. Supposing that preload P is working on both nuts A and B as in Fig.3.8, axial displacement p occurs on both, as shown in Fig.3.6. If axial load Pa is exerted externally under these conditions, nut A axial displacement occurs. It can be expressed as follows: Fig.3.8 Loads on Preloaded Ball Screws A p a Nut B axial displacement is expressed as follows: B p a Therefore, the loads working on the respective nuts can be expressed as follows: A p a a B p a If axial load Pa enlarges and external axial displacement on nut B( ) becomes zero B eventually ( ), A equals a b . p Therefore, the following equations are established: p • p and p • b ( ) b p b p p Fig. 3.9 Relationship between Nut Based on these equations, b can be expressed as follows: These equations show that, when an axial load is approximately three times as large as the preload(load), axial displacement is p. This means that, compared with when no preload is given, the ball screw is twice as rigid. A preload is effective when the external axial load is approximately three times as large as the preload or less. It is recommended, therefore, to apply a preload that is approximately one-third the maximum axial load. Fig.3.10 shows two curves of nut axial displacement, one without a preload, the other Fig. 3.10 Difference in Nut Axial Displacement with a preload. between with a Preload and without a Preload 21
- 20. TIC Precision Ball Screw Specifications 3) Preloading torque values measured by reciprocating the nut on the effective threaded portion. Preloaded ball screws are exposed to dynamic It can be larger or smaller than the torque. Terminology related to the torque, a average actual torque. torque calculation equation, and an allowable torque variation range are given below. Actual torque variation ratio: The ratio of actual torque variations to (a) Preloading torque terminology average actual torque. Preloading dynamic torque: An amount of dynamic torque which is (b) Reference torque ( p ) calculation equation required to rotate the shaft or the nuts Reference torque p on a preloaded ball continuously when the ball screw is given screw can be calculated with equation 3.1 a specified. given below: Reference torque: A target amount of preloading dynamic torque. p p Torque variations: Variations in the target preloading dynamic torque. They can be larger or smaller than Where, the reference torque. p : Reference torque, Torque variation ratio: p : Preload, The ratio of torque variations to reference torque. Actual torque: : Lead, Preloading dynamic torque measured on : Lead angle, degrees an actual ball screw. Average actual torque: p The average of the maximum and minimum actual torque values measured by reciprocating the nut on the effective p : Steel ball pitch circle diameter, threaded portion. Average actual torque variations: (c) Torque variation ratio tolerances(Refer to Table 3.6.) The maximum and minimum actual torque Table 3.6 Torque Variation Ratio Tolerances Unit : Effective Threaded Portion Length Reference Up to 4,000 Up to 4,000 Over 10,000 Torque Relation of(screw length / screw Relation of(screw length / screw - ( ) O.D.): 40 or Less O.D.): 60 or Less Tolerances Class Tolerances Class Tolerances Class Over Le s s ( R e m a r k s ) 1) Relation of screw length / screw O.D. refers to the value obtained by dividing the threaded portion length by the shaft nominal outer diameter. 2) Those of reference torque 0.2 or less are controlled based on other TIC standards .22
- 21. TIC Precision Ball Screw SpecificationsP recision of ball screw fittings *Fig. 3.11 shows what items should be checked (4) Perpendicularity of the nut reference end face or flangeregarding the precision of ball screw fittings. Each installation face to the shaft axis.item is outlined below: (5) Concentricity of the nut outside surface(cylindrical) to the shaft axis.(1) Redial deviation of the shaft supporting part (6) Parallelism of the nut fitting surface(installation plane) to cylindrical surface to the axis of the threaded the shaft axis. portion. (7) Total radial deviation of the shaft axis.(2) Concentricity of the ball screw fitting to the shaft These precision control items are as specified in JIS B supporting part axis. 1191 and B 1192. Some tolerances at TIC are stricter JIS.(3) Perpendicularity of the bearing installation face to the shaft supporting part axis. Fig. 3.11 Precision of Ball Screw FittingsDefinition of product NO *TIC Precision ball screws are identified by a numbering system as show below. Each number or letter represents amajor specification. No. of circuit (No. of turns X No. of row) Overall shaft length ( ) Precision class Thread length ( ) Thread direction (No letter: Right-handed/ L: Left-handed) Lead ( ) Shaft diameter ( ) Nut type code (Refer to Page 7) 23
- 22. Selection of Precision Ball Screws Allowable axial load * Select a ball screw of an appropriate shaft diameter r : Shaft root diameter, which will not be buckled axially under the maximum : Distance between effective load centers, compression load. : Factors to be used according to the ball screw An allowable axial load on the shaft can be obtained Supported - Supported =1 by equation 4.1 given below. Fixed - Supported =2 Fixed - Fixed =4 2 ( ) 2 Fixed - Free =0 . 2 5 Where, Fig. 4.1 is a diagram of allowable axial loads for TIC : Allowable axial load, precision ball screws. Please refer to it in selecting : Safety factor (0.5) the minimum shaft diameter required in terms of axial : Young s modulus (2.06x10 5 ) load accommodation. : Shaft minimum geometrical moment of inertia, 4 4 r 64 Fig. 4.1 Allowable Axial Load Diagram24
- 23. Selection of Precision Ball ScrewsMaximum allowable speed * : Shaft minimum cross-sectional area,1) Critical speed r 2 A ball screw rotates while bending by the weight 4 of the shaft. When the rotation speed is close to the shaft s : Factors to be used according to the ball screw resonant point, resonance may occur. Supported- Supported Therefore, ball screws need to be used in such a F i x e d -S u p p o r t e d way that its rotation speed does not reach the Fixed-Fixed resonance-starting point (critical speed). Fixed-Free The critical speed can be obtained by equation 4.2 below. 2) 60 x 2 x 10 9 The maximum allowable speed is restricted by steel 2 ball peripheral speed, as well. Where, ≦ 70 ,0 0 0 Where, : Critical speed, : Steel ball pitch diameter, : Safety factor (0.8) : Young s modulus(2.06x10 5 ) : Rotation speed, : Shaft minimum geometrical moment of inertia, Products beyond the above allowable values are 4 r also available. Please consult TIC for such special 64 products. Fig. 4.2 is a diagram of allowable rotation speeds for r : Shaft root diameter, TIC precision ball screws. Please refer to it in : Distance between effective load centers, selecting the best shaft diameter for a given set of : Steel density(7.85) rotation speed conditions. Fig. 4.2 Allowable Rotation Speed Diagram 25
- 24. Selection of Precision Ball Screws Installation methods * Fig. 4.3 shows representative ball screw installation methods. How a ball screw is installed has considerable effect on allowable axial loads, i.e., for buckling prevention, as well as on allowable speed ranges, determined so as not to reach a critical speed. Select an installation method considering these points of view. For special installation method and application under severe operating conditions, consult TIC. Fig. 4.3 Ball Screw Representative Installation Methods26
- 25. Selection of Precision Ball ScrewsLife *Ball screw life is expressed as a total number of A required ball screw life is determined dependingrotations the screw makes before flaking occurs on on the equipment to which the screws are applied,the groove or steel ball surfaces due to rolling as well as on rotation conditions.fathgue resulting from repeated stresses. Table 4.1 shows average life required for ball screws:In order to obtain the rated life of ball screws, theyare rotated in a group under the same conditions. Table 4.1 Average life Required for Ball ScrewsThe total number of rotations which 90% of ballscrews can make without flaking is called the rated Machine Type Life in Hourslife. The axial load under which the ball screw srated life is 10 6 times of rotation is called the basic Machine tools 20,000 hoursdynamic load capacity ( ) . Industrial machines 10,000 hoursThe basic dynamic load capacity values are given in Automatic control equipment 15,000 hoursthe Ball Screw Dimension Tables. Measuring instruments 15,000 hours1) Estimation of life Fig. 4.4 shows the relationship between rotation The rated life is expressed in terms of the total speed, life in hours, and the ratio of the basic number of rotations, the total rotations hours, and dynamic load capacity to the axial load.(However, the total running distance. They can be the data applies to smooth, impact-free rotation.) calculated by equations 4.3, 4.4 and 4.5. Total number of rotations ( ) x10 3 6 (4 .3 ) Total rotation hours h (4 .4 ) 60 Total running distance s (4 .5 ) 1 06Where, Total number of rotations, Total rotation hours, Total running distance, Basic dynamic load capacity, Axial load, Rotation speed, Lead, : Load factor For smooth, impact-free rotation : 1 . 0 ~1 . 2 For rotation under average conditions : 1 . 2 ~ 1 . 5 For rotation with impact : 1 . 5 ~3 . 0If loads and rotation speed vary, estimate life with anaverage load and average rotation speed. For howto obtain an average load and average rotation Fig. 4.4 Ball Screw Lifespeed, refer to the care of Precision Bearings. (Smooth, Impact-free, Rotation)In case that axial load fluctuates and number ofrevolutions differs under each load, the average axialload and number of revolutions can be calculated bythe following equation for estimation of lifeexpectancy. 27
- 26. Selection of Precision Ball Screws 2) Allowable load on grooves To evaluate load conditions under a very low rotation speed or under a standstill condition, be sure that the maximum axial load is less than the basic static load capacity. The basic static load capacity is an axial load at which the sum of permanent deformations at the contact between the shaft and balls and at the contact between the nut groove and steel balls is one ten thousandth the steel ball diameter that is confirmed free from problems under a given set of operating conditions. The basic static load capacity requirement can be calculated by equation 4.6. Where, Fig. 4.6 Influence of Installation Precision on Life : Basic static load capacity, : Maximum axial load, 4) Influence of hardness : Safety factor Operation under average condition : 1 ~ 2 If a ball screw has surface hardness below 58HRC, Operation under impact and vibration : 2 ~ 4 being made from special material, ball screw life may be lower. It should be calculated by correcting the 3) Influence of unbalanced loads standard dynamic load capacity value( ) and basic static load capacity value( ) . If ball screws are exposed to unbalanced Correct the standard and with equations 4.7 loads(moment loads or radial loads), loads and 4.8. concentrate on a local part of the steel balls. This results in adverse effects on performance and may shorten ball screw life. Control installation precision extremely carefully. Where, : Basic dynamic load capacity hardness Recommended installation precision control value factor(according to data given in Fig. 4.7) Inclination error: 1/2 000 or less : Basic static load capacity hardness Misalignment: 0.020 mm or less factor(according to data given in Fig. 4.7) Fig. 4.5 Unbalanced Load Fig. 4.6 shows estimated life decrease when ball screws are exposed to moment loads. Fig. 4.7 Hardness Factors28
- 27. Selection of Precision Ball ScrewsRigidity of whole feed shaft system *To ensure high positioning precision in applicationsto precision machines such as numerically controlledmachine tools, not only rigidity between grooves andsteel balls, but also rigidity of all components of theentire feed shaft system should be evaluated.The rigidity of a feed shaft system can be expressedby equation 4.9. 1 2 3 4 Where, : Rigidity of the entire feed shaft system, Fig. 4.8 Standard Installation 1 : Shaft rigidity, 2 : Rigidity between grooves and steels balls, 3 : Rigidity of support bearing, 4 : Rigidity of nut and bearing installation fitting,1) Rigidity of the entire feed shaft system : Where, : Axial load on the feed shaft system, : Axial elastic displacement of the feed shaft system,2) Shaft rigidity : (a) Standard installation(Refer to Fig. 4.8) 10 Where, Fig. 4.9 When Both Ends Are Fixed : Minimum cross-sectional area of the shaft, E : Young s modulus(2.06 1 0 5 ) L : Distance between effective load centers, (b) When both ends are fixed(Refer to Fig. 4.9) 10 Where, ,a nd : Distance between effective load centers, Maximum axial displacement occurs when the following equation is established: In this case, can be expressed as follows: 10 29
- 28. Selection of Precision Ball Screws 3) Rigidity between grooves and steel balls : (a) Rigidity when no preload is applied(when a clearance is provided). ( ) The relationship between axial load and axial elastic displacement can be expressed Where, by equation 4.10 below: : Rigidity value specified in the dimension table, { ( )} : Axial load, : Basic dynamic load capacity, : Correction factor Where, =0 . 1 : Constant determined based on the material, =0.05(preloaded with oversize balls) shape, and dimensions.(2.4~2.6) : Contact angle between grooves and ball 4) Rigidity of support bearing : screws, degrees Angular contact ball bearings are often used to : Ball screw diameter, support ball screws. : Axial load, The rigidity of these bearings can be calculated : Number of steel balls that are exposed to by equation 4.16 below. axial loads Theoretical rigidity value is obtained based on elastic displacement between grooves and steel balls under an axial load which is equivalent to 30% Where, of basic dynamic load capacity . : Preload on support bearing, The value is as shown in the Dimension Tables. In : Axial elastic displacement to the preload, normal applications, assume rigidity to be 80% of the value to be safe. Rigidity value under conditions where axial load { ( )} is different from three-tenths of can be calculated : Contact angle, degrees by equation 4.11. : Steel ball diameter, : Number of steel balls ( ) Where, 5 ) Rigidity of nut and bearing installation fitting : : Rigidity value specified in the dimension table, The rigidity of nut and bearing installation fitting : Axial load, should be examined thoroughly when designing : Basic dynamic load capacity, to ensure high rigidity. (b) Rigidity when a preload is applied Theoretical rigidity value is obtained based on elastic displacement between grooves and steel balls under a preload which is equivalent to 10%(or 5% for single-nut screws preloaded with oversize balls) of basic dynamic load capacity . The value is as shown in the dimension table. In normal applications, assume rigidity to be 80% of the value to be safe. Rigidity value under conditions where axial load is different from one-tenth(or one twentieth) of can be calculated by equation 4 .1 2 .30
- 29. Selection of Precision Ball ScrewsDriving torque*1) Ball screw torque 2) Motor driving torque Ball screw torque can be calculated based on Torque required to drive a mechanical system in operating conditions and an applied preload. counteraction to external loads can be calculated as follows: (a) Normal action Torque produced when a ball screw converts (a) Driving torque at constant speed rotary motion into linear motion can be calculated by equation 4.15. 1 x 1 0 -3 1 ( 1 B ) 1 Where, Where, 1 : Driving torque at constant speed, : Normal action torque, 1 : +9 . 8x : Axial load, 1 : Axial component on the shaft, such as : Lead, cutting power, 1 : Normal action factor (0.9~0.95) : Movable component mass, : Sliding face friction coefficient (b) Reverse action B : Support bearing dynamic torque, Torque produced when a ball screw converts linear motion into rotary motion can be (b) Driving torque during acceleration calculated by equation 4.16. 2 1 2 2 x 1 0 -3 Where, M s ( ) : Reverse action torque, 1 : Axial load, Where, : Lead, : Maximum driving torque during acceleration, 2 : Reverse action factor (0.7~0.85) : Motor angular acceleration, : Motor inertial moment, (c) When a preload is applied : Shaft inertial moment, Dynamic torque produced by a preload can : Gravitational acceleration( ) be calculated by equation 4.17. D x 1 0 -3 Where, D : Preloaded nut dynamic torque, : Preload, : Lead, : Preload torque factor( 0 . 2 ) Fig. 4.10 Motor Driving Torque 31
- 30. Ball ScrewT Series P recision Ball Screws T Series (Tube Ty pe ) The T series fits the widest variety of applications among all the whole series. They are suitable for standard manufacture. 1) TF Type (Tube Type, Flange, Single-nut) This type of ball screw has the simplest structure, provided with a single nut. The flange shape can be selected from between round (A) and notched (B). Select the most suitable depending on the space and installation position. TSF Type (No preload) This ball screw has a little axial clearance. YTF Type (Preloaded with Oversize Balls) This ball screw is preloaded with balls that are slightly larger than the groove dimension of the shaft and nut. The loading balls and spacer balls are used at a 1-to-1 ratio. This type of ball screw is suitable in applications where lightly preloaded ball screws are required. TFP Type (Integrally Preloaded) This ball screw is preloaded by shifting the screw lead of nut so as to produce an appropriate preload. This is the same system as used in double-nut ball screws, though this ball screw has a single nut. This type of ball screw is suitable in applications where lightly preloaded or medium preloaded ball screws are required. 2) TFN Type (Tube Type, Flange, Double-nut) A spacer to produce an appropriate preload is built between the two nuts. This type of ball screw is suitable in applications where medium- preloaded or heavily preloaded ball screws are required. 3) TFF Type (Tube Type, Flange-to-flange, Double-nut) A spacer to produce an appropriate preload is built between the two nuts. This type of ball screw is suitable in applications where medium- preloaded or heavily preloaded ball screws are required. For the construction of nuts, please refer to Table 1.1, TIC Precision Ball Screws: Types, Series, and Construction given in the engineering data section. For preload, please refer to Section 3.6, Preload and preload torque which is also included in the engineering data section.
- 31. Precision Ball Screws Dimension Table TSF Tube Type, Flange, Single-nut Ball Screws (No Preload) 1) Wiper When placing an order, please specify whether or not a wiperT Series should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with a wiper is shown above the center line, and that without a wiper is shown below . 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when the ball screw is under an axial load that is equal to 30% of the basic dynamic load capacity ( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 36
- 32. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 37
- 33. Precision Ball Screws Dimension Table TSF Tube Type, Flange, Single-nut Ball Screws (No Preload) 1) Wiper When placing an order, please specify whether or not a wiperT Series should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with a wiper is shown above the center line, and that without a wiper is shown below . 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when the ball screw is under an axial load that is equal to 30% of the basic dynamic load capacity ( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 38
- 34. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 39
- 35. Precision Ball Screws Dimension Table TSF Tube Type, Flange, Single-nut Ball Screws (No Preload) 1) Wiper When placing an order, please specify whether or not a wiperT Series should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with a wiper is shown above the center line, and that without a wiper is shown below . 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when the ball screw is under an axial load that is equal to 30% of the basic dynamic load capacity ( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 40
- 36. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 41
- 37. Precision Ball Screws Dimension Table TSF Tube Type, Flange, Single-nut Ball Screws (No Preload) 1) Wiper When placing an order, please specify whether or not a wiperT Series should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with a wiper is shown above the center line, and that without a wiper is shown below . 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when the ball screw is under an axial load that is equal to 30% of the basic dynamic load capacity ( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 42
- 38. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 43
- 39. Precision Ball Screws Dimension Table YTF Tube Type, Flange, Single-nut Ball Screws (Preloaded with Oversize Balls) 1) Wiper When placing an order, please specify whether or not a wiperT Series should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with a wiper is shown above the center line, and that without a wiper is shown below. 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when an axial load is working on the ball screw which is under a preload that is equal to 5% of the basic dynamic load capacity( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. 4) Basic load capacity Loading balls and spacer balls are used at a 1-to-1 ratio. The values are different form those of TSF type, which are not preloaded. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 44
- 40. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 45
- 41. Precision Ball Screws Dimension Table YTF Tube Type, Flange, Single-nut Ball Screws (Preloaded with Oversize Balls) 1) Wiper When placing an order, please specify whether or not a wiperT Series should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with a wiper is shown above the center line, and that without a wiper is shown below. 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when an axial load is working on the ball screw which is under a preload that is equal to 5% of the basic dynamic load capacity( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. 4) Basic load capacity Loading balls and spacer balls are used at a 1-to-1 ratio. The values are different form those of TSF type, which are not preloaded. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 46
- 42. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 47
- 43. Precision Ball Screws Dimension Table YTF Tube Type, Flange, Single-nut Ball Screws (Preloaded with Oversize Balls) 1) Wiper When placing an order, please specify whether or not a wiperT Series should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with a wiper is shown above the center line, and that without a wiper is shown below. 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when an axial load is working on the ball screw which is under a preload that is equal to 5% of the basic dynamic load capacity( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. 4) Basic load capacity Loading balls and spacer balls are used at a 1-to-1 ratio. The values are different form those of TSF type, which are not preloaded. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 48
- 44. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 49
- 45. Precision Ball Screws Dimension Table TFP Tube Type, Flange, Single-nut Ball Screws (Integrally Preloaded ) 1) Wiper When placing an order, please specify whether or notT Series wiper should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with wiper is shown above the center line, and that without wiper is shown below. 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when an axial load is working on the ball screw which is under a preload that is equal to 10% of the basic dynamic load capacity( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 50
- 46. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 51
- 47. Precision Ball Screws Dimension Table TFP Tube Type, Flange, Single-nut Ball Screws (Integrally Preloaded ) 1) Wiper When placing an order, please specify whether or notT Series wiper should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with wiper is shown above the center line, and that without wiper is shown below. 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when an axial load is working on the ball screw which is under a preload that is equal to 10% of the basic dynamic load capacity( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 52
- 48. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 53
- 49. Precision Ball Screws Dimension Table TFP Tube Type, Flange, Single-nut Ball Screws (Integrally Preloaded ) 1) Wiper When placing an order, please specify whether or notT Series wiper should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with wiper is shown above the center line, and that without wiper is shown below. 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when an axial load is working on the ball screw which is under a preload that is equal to 10% of the basic dynamic load capacity( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 54
- 50. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 55
- 51. Precision Ball Screws Dimension Table TFP Tube Type, Flange, Single-nut Ball Screws (Integrally Preloaded ) 1) Wiper When placing an order, please specify whether or notT Series wiper should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with wiper is shown above the center line, and that without wiper is shown below. 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when an axial load is working on the ball screw which is under a preload that is equal to 10% of the basic dynamic load capacity( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 56
- 52. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 57
- 53. Precision Ball Screws Dimension Table TFN Tube Type, Flange, Double-nut Ball Screws 1) Wiper When placing an order, please specify whether or not a wiperT Series should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with a wiper is shown above the center line, and that without a wiper is shown below. 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when an axial load is working on the ball screw which is under a preload that is equal to 10% of the basic dynamic load capacity( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 58
- 54. Precision Ball Screws Dimension Table T Series Unit : mm Nut DimensionsNut No. 59
- 55. Precision Ball Screws Dimension Table TFN Tube Type, Flange, Double-nut Ball Screws 1) Wiper When placing an order, please specify whether or not a wiperT Series should be provided, as nut lengths are different. In the illustration on the far right, the shape of a nut with a wiper is shown above the center line, and that without a wiper is shown below. 2) Rigidity Rigidity values given in the table are calculated based on axial elastic displacement that occurs between grooves and steel balls when an axial load is working on the ball screw which is under a preload that is equal to 10% of the basic dynamic load capacity( ) . 3) Nut flange shape The nut flange shape should be selected form between type A (standard) and type B, depending on the space and installation position. Sh a f t Ball Center Shaft Root No. of Basic Load Rigidity Ou t s i d e Le ad Ball Dia. Circular Dia. Di a . Tr a c k s Capacity Nut No. Di a . Turn Circuit 60

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