In recent years, with the rapid development of the logistics industry, the circular shuttle has been widely used in the production of various industries such as automatic warehouses, medicine, tobacco and bottled boxed products. Accurate characteristics and gradually gain the recognition of the majority of users. The circular shuttle (usually in the form of a monorail) is developed from a reciprocating shuttle. The track is arranged in a closed loop in the plane. The shuttle runs unidirectionally along the track. The circular track can run multiple shuttle cars at the same time, thereby improving the reciprocating The shortcoming of the shuttle’s limited transportation capacity.

1.1 Main technical indicators

 
project
Parameter value
1
 Linear running speed (m / min) 120
2
 Turning speed (m / min) 40
3
 Conveying speed (m / min) 12
3
 Positioning accuracy (mm) ± 0.5
4.
 Maximum load (kg) 1000
5
 control method PLC
6
 way of communication Wireless Ethernet
7
 Speed ​​mode Variable frequency stepless speed regulation
8
 Power supply Sliding touch power supply
9
 Walking motor 1.5kW two
10
 Conveyor motor 0.55kW

1.2 Structure and working principle

The circular shuttle is mainly composed of rail, car body, walking wheel, walking motor, walking wheel guide mechanism, conveyor, conveyor motor, universal wheel, sliding contact power supply system, polyurethane buffer and control system. The minimum turning radius of the circular track is R500, and the sides of the outer track are the guide surfaces. Two walking wheels are installed on the car body, and the walking motor is installed on the side of the walking wheel, which is directly driven. Two walking wheels with rotating mechanism and front and back with guide mechanism, four guide wheels are hugged on both sides of a track to ensure that the walking wheel can walk freely according to the designed curve. The other wheel is a universal wheel, without guide, and runs directly on the inner track plane. The conveyor is installed on the car body and docks with the input and output platforms around it. The control system adopts sliding contact power supply and bar code positioning. The distance detection sensors and mechanical polyurethane buffers are installed at both ends of the car body to ensure the safety of the ring shuttle.

1.3 Parameter calculation

   Driving force:
      F = m · g · [2 / D · (μ · d / 2 + f) + C]
       = 2000 · 10 · [2/200 · (0.005 · 40/2 + 0.5) +0.003]
        = 185N
          F — driving force, N
          m — self-weight + load, Kg
          g — gravity acceleration, m / s2
          D — diameter of walking wheel, mm
          d — Shaft diameter, mm
          μ — friction coefficient of rolling bearing, generally 0.005
          f — Rolling friction lever arm, steel to steel 0.5mm
          C — additional factor of secondary friction, 0.003 for wheels with rolling bearings
   Motor Power:
      P = F · V / (1000 · η)
       = 185 · 2 / (1000 · 0.5)
       = 0.74Kw
     P — power, Kw
     V — speed, m / s
     1.5Kw for the motor of the turning shuttle
 
   Calculation of output speed of reducer:
      N = V · 60 · 1000 / (3.14 · D)
       = 2 · 60 · 1000 / (3.14 · 200)
       = 191
 

1.4 Equipment characteristics

a. Double-track circular lane, three walking wheels structure, two-wheel drive, to achieve a 90-degree turn with a small turning radius.
b. The sliding contact line is installed on the outside of the track, and the current collector is installed on the walking wheel, swings with the walking wheel, and has good contact with the sliding contact line.
c. A barcode reader is installed on the walking wheel, and a barcode tape is installed on the circular track. The shuttle will not lose steps at the curved track, ensuring safe and reliable walking and scheduling.
d. The minimum turning radius of the curve is 500mm.

1.5 Control system description

a. The ring shuttle uses sliding contact power supply.
b. Traveling and cargo transportation are controlled by frequency converter, stepless speed regulation.
c. Walking two-wheel drive ensures smooth running of the shuttle under small turning radius.
d. The application of barcode simplifies the position and speed control, the maintainability of the system is greatly improved, and it is also very simple to add vehicles or platforms.
e. Based on the wireless Ethernet communication system, the running status of the shuttle car (loading / unloading, the walking position of the shuttle car, etc.) can be displayed in real time, and all shuttle cars can be coordinated to operate.

f. The distance detection sensor can detect the position of the front and rear shuttle cars to ensure safety.

Conclusion

The circular shuttle car is developed from a reciprocating shuttle car. On the same circular track, there can be multiple shuttle cars running at the same time, making up for the shortcomings of the insufficient transport capacity of the reciprocating shuttle car. When the running route is not on a straight line, the transportation of goods needs to be sorted, and there are many platforms, a monorail ring shuttle is generally used for the overall layout of the system. However, with the increase in the number of shuttles, the difficulty of the dispatching system has also greatly increased, and the traffic jams of the vehicles will be very serious, but will cause the capacity of the entire system to decline.

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