11 KiB
Shredder for Q1 2021
Latest update: Gearboxes
Gearbox selected will be the Cidepa CKM-67.3 1/60 3
Reference CKM-67.3 1/60 3
Installed HP 3,00
Installed Kw 2,20
Ratio 60,0
Motor Option Cidepa electric motor B-5
Mounting Position Feet
Output Shaft diameter 40
Size 67
Service Factor 0,90
Rated Torque Nm 890,00
Output Rpm 23,00
Accurate gear ratio 60,66
F. Radial Fr2 (N) 9.490,00
Gear trains 3
Weight 61,00 Kg.
The motor is an MT4 1500 which is actually rated at 3kw, guess they make an allowance for the gearbox efficiency.
So the next question is about the gears, what size/module is needed.
Max torque is 890Nm shared between the two shafts, so the transmitted torque will be 445Nm
https://shop.hpceurope.com/docFichesTechniques/SpurGear_TorqueCalculation.pda
https://www.engineersedge.com/gear_formula.htm
https://www.engineersedge.com/calculators/gear-tooth-strength-calculator.htm
https://www.mechanicdrive.com/spur-gear-calculation
https://khkgears.net/new/gear_knowledge/gear_technical_reference/gear_materials.html
for equal gears 1:1, the axle centre distance = pitch diameter; we need as low as possible but minimum 82
MODULE 4
A module 4 gear with 21 teeth has a pitch circle diameter of 84mm and an outside diameter of 92mm.
Off the shelf gear part number 7702-910 has a face width of 40mm
DP size is 6 (how many teeth will fit on 1" of the gear cirumference)
According to the calculator, with a Lewis factor of 0.34, a carbon steel this size gear will transmit 369Nm
This is insufficient.
MODULE 5
A module 5 gear with 17 teeth has a pitch circle diameter of 85mm
This has an estimated Diametric pitch of 4, so a carbon steel gear of face width 50mm could transmit 554Nm
https://www.mechanicdrive.com/spur-gear-module-5-17-teeth.html
The total length including hub is 75mm. The centre hole needs to be bored out to 40mm and keyway broached to suit the axle.
Rough spec:
-
single phase motor max 2.2kw frame size 100/110
-
slowest motor speed possible 1400rpm - 4 pole
-
full load current for 2.2kw motor at 1400rpm = 12.12A
-
size 110 or 90 gearbox ?
-
slow speed ideally around 20rpm
-
40mm shaft, 50mm hex section
-
mod 4 or 5 gears?
-
1/3 size of Chinese version and similar
-
bearing set into endplate
-
axles as close together as possible
-
15mm thickness steel
-
laser cut and finshed with mill or cnc
-
cutting edges parallel to axle (straight cut)
-
alternating blades and spacer rings
Previous research:
My research suggests that the NMRV size 90 gearbox can only go down to 44rpm with a 1400 rpm 2.2kw motor. This is a 30:1 ratio.
The high ratio NMRV 90 gearboxes can only be used with lower power motors as the output shaft is too small. The max output of an NMRV gearbox is around 270Nm with whichever combination of motor and ratio.
The size 90 gearbox at 80:1 can be used with a 0.75kw (1hp) motor to give 262 Nm at 18rpm. NMRV 'Power' 90 at 100:1 apparently gives 270Nm. These have a max output shaft size of 38mm on request, standard is 35
The size 90 gearbox at 60:1 can be used with a 1.1kw motor to give 288Nm at 23.3rpm.
110 size gearbox:
With a 2.2kw motor,
The NMRV 110 gearbox at 80:1 gives 648 Nm at 23.3rpm
We could also consider a helical gearbox which can give 877Nm at 23rpm through a 40mm output shaft. This is around 900 euros including 2.2kw motor. It's inline so would be awkward for design, but much higher torque than a worm drive. Even an NMRV 130 can only give 816 Nm at 17.5rpm.
Bearing options
Ball bearings:
6308-2RS Dunlop Sealed Ball Bearing 40mm x 90mm x 23mm = £9.32 each
62208-2RS1 SKF Sealed Ball Bearing 40mm x 80mm x 23mm = £21.59 each
Roller bearings:
NU2208 ECP SKF Cylindrical Roller Bearing 40mm x 80mm x 23mm = £45.11 each
Static Load: 75kN Dynamic load: 81.5kN
NUP308 ECP SKF Cylindrical Roller Bearing 40mm x 90mm x 23mm = £59.88 each
Static Load 78kN Dynamic Load: 93kN
Motor:
Cidepa KM 2.2kW 1400rpm
60:1 gearbox Cidepa
Reference KM-110/ 60 3 Installed HP 3,00 Installed Kw 2,20 Ratio 60,0 Motor Option Cidepa electric motor B-5 Size 110 Service Factor 0,90 Rated Torque Kpm 68,19 Output Rpm 23,00 Efficiency 0,73 Accurate gear ratio 60,00 HP available 2,19 Weight 40,50 Kg.
Size: 295 x 255 x 144mm
Torque calcs
TNm = PW 9.549 / n
where
TNm = torque (Nm)
PW = power (watts)
n = revolution per minute (rpm)
Motor axle 2.2kw x9.549 / 1400 =15Nm
After gearbox =2.2kw x 9.549 / 23.3
T = 901.6Nm
(To check, 15Nm x 60 = 900Nm)
At 73% efficiency T = 658.2Nm
So roughly 650Nm
If the motor is 2800rpm, torque will be half.
Gears:
need to establish torque, size, module, supplier
Assuming trying to achieve minimum distance between axles, using 80mm roller bearings, minimium axle spacing = 82mm centers
So ideal 'pitch circle' of gear = 82mm (maybe 84)
Torque Assuming 650Nm output from gearbox, divided over 2 axles, gear must transmit 325Nm
This table suggests that even some module 3 gears with a 20mm bore can withstand this force https://khkgears.net/pdf/ksg.pdf
(that seems optimistic to me)
RV Gearboxes - can we use a smaller size?
NMRV Power gearboxes from Motovario
https://www.transdrive.co.uk/media/1272/nmrv-nmrvp-catalogue.pdf
Sizes:
NMRV 90 238 x 206 x 130mm 24mm input, 38mm ouput NMRV 110 295 x 250 x 144mm 28mm input, 42mm output - NB- Cidepa equivalent KM 110 is 288 x 255 x 144 so assume 300 x 260 x 150mm and pack NMRV 130 335 x 292.5 x 155mm 38mm input, 45mm outpit
NMRVpower size 90 (Motovario)
Flange- B5 or B14?
NMRV90 is only available up to 60:1 with a B5 flange, 80 or 100:1 are B14 flange (smaller face mount)
NMRV-P090
Ratio - 60:1
Frame Size / Mounting Position : IEC80 B5
Hollow output – 35mm standard (39mm is available)
Max torque 1.550 Nm and admissible radial loads max 16.500 N
Motor size 100/110
Part number – 3043638
To get lower speeds we need a bigger gearbox, NMRV 110 or NMRV 130
According to the PDF, with a 3HP (2.2kw) motor 100LA4:
NMRV 90 at 40:1 will give an output torque of 3321 in-lb = 375 Nm at 44rpm = 67% efficient
NMRV 110 at 60:1 will give 4852 in-lb = 548 Nm at 29rpm = 62.5% efficient
NMRV 130 at 80:1 will give 5965 in-lb = 674 Nm at 22rpm
NMRV 90 at 60:1 or 80:1 are not shown on the chart but assuming the same efficiency:
NMRV 90 at 80:1 = 14.6Nm x 80 = 1168Nm, x 67% = 782.56Nm at 22 rpm
NMRV 90 at 60:1 = 14.6NM x 60 = 876Nm x62.5% = 543Nm at 33rpm
These are very high torque values which require a bigger shaft, which is why the bigger gearbox size is needed
The 110 size at 60:1 is the best compromise.
Info on the 100LA4 motor: https://new.abb.com/products/3GAA102001-ASE/m2aa-100-la4-b3-2-2kw-ac
50Hz 230V 2.20kW 1430rpm 8.52A
Service factor 0.780
Efficiency 82.30% Torque 14.60 N·m
What about parallel shaft motors? more torque? slower? YES but more expensive
JS-DV473-100-4-2,2 kW
20 rpm 1003Nm €1,225.75
14 rpm 1439Nm €1,225.75
JS-DV473-100-4-2,2 kW-26 rpm 774Nm €1,225.75
all with 50mm shaft
Compared to worm drive, all size 130 with 45mm output
JS- CMRV 110-100L1-4 - 2,2 kW - 23,3 rpm- 648 Nm €845.54
JS- CMRV 110-100L1-4 - 2,2 kW - 17.5 rpm- 816 Nm €967.51
Slowest you can go without additional prestage reducer is
JS- CMRV 090-100L1-4 - 2,2 kW - 46,7 rpm 351 Nm €668.74
Compared to Bevel drive
JS-KV373-100-4-2.2 kW-23 rpm 853Nm €1,086.47
JS-KV473-100-4-2.2 kW-14 rpm 1372Nm €1,491.64
Compared to Helical
Helical-Gear-Motor-JS-MV-373-100L1 - 2.2kW-23rpm 877Nm €887.84
With a 2.2kw motor the NMRV size 90 gearbox can only go down to 44rpm because the lower ratios give too much torque for the shaft
2.2kw motor with the Motovario 110 size NMRV 110 (same as Cidepa KM 110) at 60:1 will give 548 Nm at 29rpm. That would be within spec.
It could be fitted with an 80:1 gearbox to give 782.56Nm at 22 rpm but that is after compensating for efficiency, the actual torque would be 1168Nm so it would be above what the shaft can take.
For the best torque from a 2.2kw motor we actually need a 130 size gearbox.
with 2.2kw motor, NMRV 130 at 80:1 will give 5965 in-lb 674 Nm at 22rpm
NMRV 130 is 335 x 292.5 x 155mm 38mm input, 45mm output
CHEAP GEARBOX! : £221.20 each
Size 90 Right Angle Worm Gearbox 80:1 Ratio
18 rpm Output speed using a 4 Pole (1400 rpm) Electric Motor and 262 Nm Output Torque.
The maximum motor input size for this gearbox is 80 frame and flange size B5/B14.
frame size 80 is a 0.75kw motor at 1400rpm - can this be believed?
TNm = PW 9.549 / n
where
TNm = torque (Nm)
PW = power (watts)
n = revolution per minute (rpm)
= 5.12 NM at 64% effifciency = 3.28nm
x 80 = 262Nm Correct
.. In theory, from motovario catalogue compatibility of motors:
NMRV 90 gearbox with size 80 motor (0.75kw, 1hp) max 100:1 gives 511Nm x 64% = 327Nm
NMRV 90 gearbox with size 90 motor (1.1kw, 1.5hp) max 60:1 gives 450Nm x 64% = 288Nm
NMRV 90 gearbox with size 100 motor (2.2kw, 3hp) max 30:1 also 450Nm = 288Nm
Suggests the NMRV output is limited to around 300Nm
the NMRV 110 is available in up to 60:1 for a size 100 motor (2.2kw), which gives 900 x 64% = 576Nm
or up to 100:1 with a size 90 motor (1.1kw) which gives 750 x64% = 479Nm