ca_ra_e

High Precision Gearheads The includes gearheads for high precision control of ATC magazines, ATC arms, APC, and turret drives of lathe machining centers. Series Series � Table of Contents Examples of Use 2 to 3 For Machining Center For NC Lathe or Combined Lathe Features and Configurations 4 Principle of Operation 5 Rating Table 6 to 7 Glossary 8 to 9 Life Rating Allowable Acceleration/Deceleration Torque Momentary Maximum Allowable Torque Allowable Output Speed [Continuous] Allowable Output Speed [Intermittent] Torsional Rigidity, Lost Motion, Backlash Calculation of Torsion Angle Allowable Moment and Maximum Thrust Load Momentary Maximum Allowable Moment Allowable Moment Diagram Performance �0 to �� Efficiency Low-temperature Characteristics No-load Running Torque Selection Flowchart �2 to �3 Engineering Notes �4 to �7 Appendix � Quick Selection Table of Product Codes RA-EA Series (Case rotating type) 2� to 24 RA-EC Series (Shaft rotating type) 25 to 28 2 Examples of Use For Machining Center Contact us for NT Series rotary tables. Cam drive for ATC arms RA Series APC drive RA Series ATC magazine drive RA Series Rotary table NT Series 3 For NC lathe or combined lathe RA-EA Series RA-EC Series Lathe turret drive RA Series ATC magazine drive RA Series 4 The rotation direction of the output shaft is opposite to that of the servo motor. The rotation direction of the output shaft is the same as that of the servo motor. Tool and holder Sprocket Reduction gear Servo motor Fixed frame RA-EC Series Tool and holder Sprocket Reduction gear Servo motor Fixed frame RA-EA Series Features and Confi gurations High shock load capability High rigidity High precision High torque The double-ended support design and unique pin gear mecha- nism provide the following advantages: (1) Capable of high shock load 5 times the rated torque (2) High torsional rigidity (3) Small backlash [1 arc.min] (4) High torque density (capable of high torque with downsized gear) Heavy load support A set of internal main bearings (large angular ball bearings) enables complete support of heavy external loads. 1. Maintenance: Trouble free 2. Compact design with a reduced number of parts 3. Reduced man-hours (for design, assembly, and adjustment) Three benefi ts due to the above features 5 Principle of Operation 1. Rotation of the servo motor is transmitted through the input gear to the spur gears, and the speed is reduced according to the gear ratio between the input gear and the spur gears. 2. Since the crankshafts are directly connected to the spur gears, they have the same rotational speed as the spur gears. 3. Two RV gears are mounted around the needle bear- ings on the eccentric section of the crankshaft. (In order to balance the equal amount of force, two RV gears are mounted.) 4. When the crankshafts rotate, the two RV gears mounted on the eccentric sections also revolve eccentrically around the input axis (crank movement). 5. Pins are arrayed in a constant pitch in the grooves inside the case. The number of pins is just one larger than the number of RV gear teeth. 6. As the crankshafts revolve one complete rotation, the RV gears revolve eccentrically one pitch of a pin (crank movement), with all the RV teeth in contact with all of the pins. As a result, 1 RV gear tooth moves in the op- posite direction of the crankshaft rotation. 7. The rotation is then output to the shaft (output shaft) via the crankshaft so that the crankshaft rotation speed can be reduced in proportion to the number of pins. 8. The total reduction ratio is the product of the fi rst reduc- tion ratio multiplied by the second reduction ratio. Crankshaft Input gear Spur gear „ Fig. 1. First reduction section Crankshaft Spur gear Rotation Eccentric section Needle bearing RV gear Rotation Eccentric movement „ Fig. 2. Crankshaft section Crankshaft Rotation angle 0° Rotation angle 180° Rotation angle 360° Crankshaft (connected to the spur gear) Shaft RV gear Case Pin „ Fig. 3. Second reduction section 6 Rating Table Model Speed Ratio To No K Ts1 Ts2 Rated Torque Rated Output Speed Rated Life Allowable Acceleration/ Deceleration Torque Momentary Maximum Allowable Torque N-m (kgf-m) rpm Hr N-m (kgf-m) N-m (kgf-m) RA-EA Series RA-20EA 80 104 120 140 160 167 15 6000 412 833 (17) (42) (85) RA-40EA 80 104 120 152 412 15 6000 1029 2058 (42) (105) (210) RA-80EA 80 100 120 152 784 15 6000 1960 3920 (80) (200) (400) RA-160EA 80 100 128 144 170 1568 15 6000 3920 7840 (160) (400) (800) RA-EC Series RA-20EC 81 105 121 141 161 167 15 6000 412 833 (17) (42) (85) RA-40EC 81 105 121 153 412 15 6000 1029 2058 (42) (105) (210) RA-80EC 81 101 121 153 784 15 6000 1960 3920 (80) (200) (400) RA-160EC 81 101 129 145 171 1568 15 6000 3920 7840 (160) (400) (800) Note: 1. The Rating Table shows the specifi cation values of each individual reduction gear. 2. The allowable output speed may be limited by heat depending on the operating rate. 3. For the inertia moment of the reduction gears, refer to the Product Summary Sheet. 4. For dimensions α and L, refer to “Allowable Moment and Maximum Thrust Load.” 7 Capacity of main bearing Ns1 Ns2 Mo Ms1 Fo α L Allowable Output Speed [Continuous] Allowable Output Speed [Intermittent] Backlash Lost Motion Torsional Rigidity (Spring Constant) Allowable Moment Momentary Maximum Allowable Moment Maximum Thrust Load Dimension α Dimension L Mass Note 4 Note 4 Note 2 rpm Note 2 rpm arc.min. arc.min. N-m/ arc.min. (kgf-m/ arc.min.) N-m (kgf-m) N-m (kgf-m) N (kgf) mm mm kg 45 75 1.0 1.0 49 882 1764 3920 63.1 113.3 10 (5) (90) (180) (400) 42 70 1.0 1.0 108 1666 3332 5194 83.1 143.7 18.5 (11) (170) (340) (530) 42 70 1.0 1.0 196 2156 4312 7840 81.5 166 28 (20) (220) (440) (800) 27 45 1.0 1.0 392 3920 7840 14700 93.8 210.9 58 (40) (400) (800) (1500) 45 75 1.0 1.0 49 882 1764 3920 122.2 113.3 9.5 (5) (90) (180) (400) 42 70 1.0 1.0 108 1666 3332 5194 148.1 143.7 20 (11) (170) (340) (530) 42 70 1.0 1.0 196 2156 4312 7840 158.4 166 27 (20) (220) (440) (800) 27 45 1.0 1.0 392 3920 7840 14700 201.8 210.9 59 (40) (400) (800) (1500) Rotating part (Shaft) Fixed part Fixed Servo motor Fixed part Rotating part (Case) Fixed Servo motor RA-EC Series (Shaft rotating type)RA-EA Series (Case rotating type) 8 Glossary Life Rating The life time when driven at the rated torque and rated output speed is called the “life rating.” Allowable Acceleration/Deceleration Torque When the machine starts or stops, the load torque to be applied to the reduction gear is larger than the constant- speed load torque due to the effect of the inertia torque of the rotating part. In such a situation, the allowable torque during acceleration/deceleration is referred to as “allowable acceleration/deceleration torque.” Note: Be careful so that the load torque, which is applied during normal operation, does not exceed the allowable acceleration/de- celeration torque. Momentary Maximum Allowable Torque A large torque may be applied to the reduction gear due to an emergency stop or an external shock. The allow- able value of the momentary applied torque at this time is referred to as “momentary maximum allowable torque.” Note: Be careful so that the momentary exces- sive torque does not exceed the momen- tary maximum allowable torque. Lo ad to rq ue Max. torque for startup Momentary max. torque Max. torque for stop Constant torque Time Allowable Output Speed [Continuous] The allowable output speed when the machine starts and stops repeatedly is referred to as “allow- able output speed [Continuous].” Note: Maintain the environment and operation conditions so that the temperature of the reduction gear case is 60ºC or lower. Allowable Output Speed [Intermittent] The allowable output speed during the operation in which the reduction gear is not activated frequently is referred to as “allowable output speed [Intermittent].” Note: Maintain the environment and operation conditions so that the temperature of the reduction gear case is 60ºC or lower. Torsional Rigidity, Lost Motion, Backlash When a torque is applied to the output shaft while the input shaft is fi xed, torsion is generated accord- ing to the torque value. The torsion can be shown in the hysteresis curve. The value of b/a is referred to as “torsional rigidity.” The torsion angle at the mid point of the hysteresis curve width within ±3% of the rated torque is re- ferred to as “lost motion.” The torsion angle when the torque indicated by the hysteresis curve is equal to zero is referred to as “backlash.” „ Hysteresis curve Backlash Lost motion a b ±100% rated torque ±3% rated torque Torsion angle Calculation of torsion angle Taking RA-160E as an example, the torsion angle will be calculated when torque is added in one direction. 1) When the load torque is 30 N-m .... Torsion angle (ST1) z When the load torque is within the lost motion area ST1= 30 x 1 (arc.min.) = 0.32 arc.min or less 47 2 2) When the load torque is 1,300 N-m .... Torsion angle (ST2) z When the load torque is within the rated torque area ST2= 1 + 1300−47.0 = 3.70 arc.min. 2 392 Note: 1. The torsion angles that are calculated above are for a single reduction gear. 2. For the customized specifi cations of the lost motion, contact us. Models Torsional rigidity (Spring Constant) N-m/arc.min. Lost motion Backlash arc.min.Lost motion arc.min. Measured torque N-m RA-20E 49 1.0 ± 5.0 1.0 RA-40E 108 ± 12.3 RA-80E 196 ± 23.5 RA-160E 392 ± 47.0 9 Allowable Moment and Maximum Thrust Load The external load moment may be applied to the reduction gear during normal operation. . The allow- able values of the external moment and the external axial load at this time are each referred to as “allow- able moment” and “maximum thrust load.” Mc : Load moment (N-m) W1, W2 : Load (N) L1, L2 : Distance to the point of load application (mm) α : Designated dimension (mm) (Refer to the Rating Table.) L : Designated dimension (mm) (Refer to the Rating Table.) Mc = W1 x (L1 + α) + W2 x L2 1000 Mc Allowable moment Note: 1. When the load moment and the thrust load are applied concurrently, ensure that the reduction gear is used within the corresponding allowable moment range, which is indicated in the allow- able moment diagram. 2. When W1 load is applied in the area of the dimension L, use it within the allow- able radial load, calculated using the formula below. Allowable radial load = Allowable moment : (N) L RA-EA L α L1 W1 W2 L2 RA-EC W1 W2 L2 L1 α L Momentary Maximum Allowable Moment A large moment may be applied to the reduction gear due to an emergency stop or external shock. The allowable value of the momentary applied mo- ment at this time is referred to as “momentary maxi- mum allowable moment.” Note: Be careful so that the momentary exces- sive moment does not exceed the momen- tary maximum allowable moment. Allowable Moment Diagram Load moment (N-m) Th ru st lo ad (N ) 2156 3920882 1666 25201660 7840 14700 5194 3920 3410 4890 3040 2040 1450735 20E 80E 160E 40E 10 Performance Effi ciency RA Sries Case temperature: 30°CLubricant: Grease (Molywhite RE00) Output torque (N-m) 20E 40E 80E 160E 10rpm 30rpm 60rpm 50 100 150 200 20 40 60 80 100 0 20 40 60 80 100 0 10rpm 25rpm 50rpm 100 200 300 400 500 10rpm 25rpm 50rpm 250 500 750 1000 20 40 60 80 100 0 20 40 60 80 100 0 10rpm 25rpm 40rpm 500 1000 1500 2000 E ffi ci en cy (% ) E ffi ci en cy (% ) E ffi ci en cy (% ) E ffi ci en cy (% ) Output torque (N-m) Output torque (N-m) Output torque (N-m) 20E Case temperature (˚C) N o- lo ad ru nn in g to rq ue In pu t a xi s (N -m ) N o- lo ad ru nn in g to rq ue In pu t a xi s (N -m ) N o- lo ad ru nn in g to rq ue In pu t a xi s (N -m ) N o- lo ad ru nn in g to rq ue In pu t a xi s (N -m ) Speed ratio Case temperature (˚C) Speed ratio Case temperature (˚C) Speed ratio Case temperature (˚C) Speed ratio 57 105 1410 1 2 -10 0 10 20 40E 80E 160E 57 121 153 0 1 2 3 4 5 -10 0 10 20 57 121 1710 2 4 6 8 10 -10 0 10 20 81 129 171 0 5 10 15 -10 0 10 20 Low-temperature characteristics (No-load running torque for low-temperature range) RA Series RA Series: Input speedLubricant: Grease (Molywhite RE00) 11 No-load running torque RA Series Case temperature: 30°CLubricant: Grease (Molywhite RE00) The no-load running torque that is converted to the input shaft side value should be calculated using the following equation: No-load running torque on the input shaft side (N-m) = No-load running torque on the output shaft side (N-m) Speed ratio 0 20 40 60 80 100 50 100 150 200 80E 20E 40E 0 10 20 30 40 50 50 100 150 200 250 300 350 400 450 500 550 160E Output shaft speed (rpm) N o- lo ad ru nn in g to rq ue o n th e ou tp ut s ha ft si de (N -m ) N o- lo ad ru nn in g to rq ue o n th e ou tp ut s ha ft si de (N -m ) Output shaft speed (rpm) 12 Selection Flowchart Decrease the load Calculation of life (Lh) Examine the input speed T1orT3 Allowable acceleration/ deceleration torque Tem Momentary maximum allowable torque Check the load torque applied to the reduction gear. An example is shown in the load cycle diagram. Tm = t1 · N1 · T1 + t2 · N2 · T2 + ..... tn · Nn · Tn t1 · N1 + t2 · N2 + ..... tn · Nn 10 3 10 3 10 3 10 3 Nm = t1 · N1 + t2 · N2 + ..... tn · Nn t1 + t2 + ..... tn Lh = 6000 x x No Nm To Tm( ) 10 3 Cem = 60 Nem 40 x x tem 10 35 × To Tem 775 x ( ) NO NO YES YES YES YES YES YES NO NO Tout: Assumed values NO Input speed Speed Ratio Maximum allowable output speed Momentary maximum allowable torque NO Tout (1) Examine the load characteristics ● Examine the average load torque (Tm) ● Examine the average output speed (Nm) Temporary selection of the model from the rating table Increase the model number of the reduction gear Lh ≥ Required life Examine the acceleration/decelerati on torque (T1, T3) Examine the external impact torque (Tem) due to an emergency stop Examine the external impact torque (Tout) when motor shaft is not rotating. Calculation of allowable applied speed (Cem) Actual applied speed ≤ ≤ ≤ ≤ Cem≤ Load cycle diagram R ot at io n lo ad to rq ue R P M Max. torque for startup External impact torque Constant torque Max. torque for stop Shock time tem  Deceleration time Acceleration time Constant drive time Deceleration time T1 T2 0 T3 Tem Nem t1 t2 t3 N2 N1 N3 Time 13 Determine the model END NO YES NO YES (Refer to page 09) Mc = {W1 x (α1 + L1) + W2 x L2) x 10-3 Mc ≤ Mo Nm = = 15.6r.p.m.0.2 x 10 + 0.5 x 20 + 0.2 x 10 0.2 + 0.5 + 0.2 Selection examples Tm = = 1,475N-m 0.2 x 10 + 0.5 x 20 + 0.2 x 10 10 3 10 3 10 3 10 30.2 x 10 x 2,500 + 0.5 x 20 x 500 +0.2x10x1,500 T1 = 2,500N-m T2 = 500N-m T3 = 1,500N-m Tem = 7,000N-m t1 = 0.2sec t2 = 0.5sec t3 = 0.2sec tem = 0.05sec N1 = N3 = 10r.p.m. N2 = 20r.p.m. Nem = 20r.p.m. 2,405.4N-m < 3,920N-m Lh = 6000 x x = 7,073Hr 7,073 > 5,000 15 15.6 ( )1,5681,475 10 3 Maximum allowable output speed of RA-160EC [Continuous] Allowable acceleration/deceleration torque of RA-160EC Momentary maximum allowable torque of RA-160EC Required life Rated torque of RA-160EC Mc = (201.8 + 500) 1,000 200 1,000 ( ) Cem = =1696 times 20 6040 x x 0.05 10 35×1,568 7,000 775 x z External load conditions W1 = 3,000N L1 = 500mm W2 = 1,500N L2 = 200mm z Examine the thrust load 1,500N < 14,700N z Examine the load moment (RA-160EC) z RA-160EC is selected (All conditions are met) (2) Examine the main bearing capacity z Examine the emergency stop and external impact torque Tem = 7,000N-m < 7,840N-m z Examine the acceleration/deceleration torque Tmax = T1 = 2,500N-m < 3,920N-m = 2,405.4N-m Maximum thrust load of RA-160EC 150 times < 1696 times Actual applied speed Allowable moment of RA-160EC z Examine the maximum output speed 20r.p.m. < 27r.p.m. Maximum allowable output speed of RA-160EC z Tentative selection of frame number Temporarily select RA-160EC from the Tm and Nm values. 1,475N-m < 1,568N-m, 15.6r.p.m. < 27r.p.m. z Calculation of life z Calculation of average output speed z Calculation of average load torque z Usage conditions (1) Examine the load characteristics + 1,500 x 3,000 x (2) Examine the main bearing capacity Check the external load applied to the reduction gear. When the load moment and the thrust load are applied concurrently, ensure that the reduction gear is used within the corresponding allowable moment range, which is indicated in the allowable moment diagram. Examine the thrust load (W2) ● Increase the model number ● Decrease W2 W2 ≤ Allowable thrust (W) ● Increase the model number ● Decrease the load Examine the load moment Mc ≤ Allowable moment (Mo) 14 Engineering Notes 1. Installation of the reduction gear and mounting it to the output shaft z When installing the reduction gear and mounting it to the output shaft, use hexagon socket head cap screws and tighten them with the torque as specifi ed below, in order to satisfy the momentary maximum allowable torque, which is noted in the rating table. Employment of the Belleville Spring Washer is recommended to prevent the hexagon socket head cap screws and protect their seat surface from fl aws. (1) Bolt tightening torque and tightening force Hexagon socket head cap screw Nominal size x pitch Tightening torque (N-m) Tightening force F (N) Bolt specifi cations M5 x 0.8 9.01 ± 0.49 9310 ‹ Hexagon socket head cap screw M6 x 1.0 15.6 ± 0.78 13180 JIS B 1176 M8 x 1.25 37.2 ± 1.86 23960 ‹ Strength class M10 x 1.5 73.5 ± 3.43 38080 JIS B 1051 12.9 M12 x 1.75 128.4 ± 6.37 55100 ‹ Thread M14 x 2.0 204.8 ± 10.2 75860 JIS B 0205 6g or class 2 M16 x 2.0 318.5 ± 15.9 103410 Note: 1. The tightening torque values listed are for steel or cast iron material. 2. If softer material, such as aluminum or stainless steel, is used, limit the tightening torque. Also, pay attention to the system requirements of the transmission torque. (2) Calculation of allowable transmission torque of bolts. T = F x D x 10 -3 x μ x n 2 T Allowable transmission torque by tightening bolt (N-m) F Bolt tightening force (N) D Bolt mounting P.C.D (mm) μ Friction factor μ=0.15 ... When grease remains on the mating face μ=0.20 .. When grease has been removed from the mating face n Number of bolts (pcs) (3) Serrated lock washer for hexagon socket head cap screw Name : Belleville Spring Washer (made by Heiwa Hatsujyo Industry Co., Ltd.) Corporation symbol : Bell SW-2H (nominal size) Material : S50CM to S65CM Hardness : HRC40 to 48 (Unit: mm) Normal size ID and OD of Belleville Spring Washer t H d Basic size D 5 5.25 8.5 0.6 0.85 6 6.4 10 1.0 1.25 8 8.4 13 1.2 1.55 10 10.6 16 1.5 1.9 12 12.6 18 1.8 2.2 14 14.6 21 2.0 2.5 16 16.9 24 2.3 2.8 Note: When using any equivalent washer, select it with special care given to its outer diameter. 15 2. Mounting the input gear z The following is a representative case for connecting an