Intro
Case study
TASK :
We should build mechanisam that will rotate (at ending shaft) same angular speed as an large (driven) gear.
Parameters :
Drive gear : z = 21
Driven gerar z = 160
The rotary bar is a device similar to a huge funnel that receives coal from a surface mine and distributes it in 3 large bunkers. It is powered by a gear motor connected to a small 21-tooth gear. It is coupled with a large gear that is rigidly connected to the reverse rod. The large gear has 160 teeth.
Situation and mounting place
solution
It is necessary to set the encoder that will get the angular velocity of the large gear, ie the rotating rod.
Due to the required precision of angular velocity, I opted for a gearbox with cylindrical gears,
This reducer does not transmit any load but only regulates the angular velocity of the large gear.
and that's why I called him speed copy reductor
Solution details
The transfer rate is
Parameters : Z2 = 160 - number of teadh on the large gear Z1 = 21 - number of teadh on the small gear Since the upper fraction cannot be shortened - it is impossible to make a model of coupled gears. If I should use straps or sprockets, it could slip and thus lead to an inaccurate angular velocity of the large gear.
With a little help by mathematic ...
If we look carefully, we should notice that the numbers 160 and 21 are divisible. Number 160 with 2.4.5.10.20.40.80 while the number 21 is divisible by 7 and 3. It follows that the transmission relationship can be pushed as well:
Now, We already have a sketch of two pairs of coupled gears, it is necessary to expand the fractions of the gear ratio so that the number of teeth is greater than the minimum.
so : 
it is the number of teeth of the first pair of gears
for the other pair of gears followed by the number of teeth
Next step -
designing the gear parameters
| Gear | Number of teath | module | note | |
|---|---|---|---|---|
| 1 | 48 | 4 | ||
| 2 | 21 | 4 | ||
| 3 | 50 | 4 | ||
| 4 | 15 | 4 | ||
| 5 | 21 | 16 | Entering gear |
Kinematic scheme of speed reducer: gear arrangement
Gear calculation
SThe next logical step is to calculate the gears. First, I determine the module taking into account the dimensions, and then the calculation of the gears follows. A handy free gear calculator is here and I used it for the calculation. After the calculation of the gears, the calculation of the shaft, bearings and the construction of the shaft and the bearing housing follows. I chose a wedge connection on all gears.
Making gearbox
After the construction and preparation of technical documentation, the entire project was handed by the company "Elmont", which made all the elements except the formwork and the base.
Gear
Gear
Shaft
Housing
circuit drawing of the speed reducer
Side view
Front view
Making formworks and the base
The base and the formwork have a role (apart from carrying and protecting the gear elements),to adjust, fit and accutity adjusting the teeth coupling.
Construction of the side formwork consisting of a cover sheet and a U-profile with grooves that also serve as sliders for moving the gearbox in the active direction
The green plate serves as the encoder carrier, the output shaft of the reducer is visible
The top picture of the plates is a stand that is used to adjust the outside gear of the input gear with a gear at the plant. The central screw is used to turn the gearbox, on the back side there will be an average circular one a slot for fixing the rear part of the gearbox in order to avoid its vibrations.
Finaly appearance of the reducer and encoder assembly on the stand.
Another view of the mounted reducer and encoder on the stand
Mounting
The strand wellding
Teath alligment control
Top view
Bottom view
pvc: 259