Design of the stepping mechanism of the hottest cl

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Design of clutch stepping mechanism

when the driving part moves continuously, the driven part moves and stops periodically. This kind of mechanism is called stepping mechanism, which is widely used in various automatic machinery to realize the working requirements of feeding, braking, indexing, indexing, surpassing, etc. There are many kinds of stepping mechanisms. Common and mature stepping mechanisms include ratchet mechanism, Geneva mechanism, cam mechanism and incomplete gear mechanism. The clutch stepping mechanism studied in this design has the characteristics of easy manufacture, small volume, accurate positioning and stable operation. As long as a simple calculation is made, the required stepping action can be reasonably matched. The mechanism is suitable for light load occasions

1 main components and actions

the clutch stepping mechanism is mainly composed of frame, cylinder, rack, gear clutch, transmission clutch, spring adjusting screw sleeve, guide rail, bearing, bearing Xiang, main shaft, main chain wheel, transmission sprocket, transmission sprocket, transmission shaft, chain, etc. The structure is shown in Figure L

when the cylinder piston is at the zero position, the gear clutch and transmission clutch teeth are in the "closed" state, and the inclined surfaces of the two clutch teeth are close to each other. This kind of material is the basic element to implement lightweight technology and comply with federal Cafe guidelines when the piston "pushes" the force. When running in the direction, the gear clutch and transmission clutch are still in the "closed" state. The rack makes a linear motion in the guide rail to drive the gear clutch, and drives the transmission clutch and the main shaft to rotate through the tooth. At the same time, the main chain wheel drives the transmission sprocket of the transmission sprocket shaft, driving the chain on the transmission sprocket to make a linear motion; When the piston moves in the "return" direction, under the action of the inclined surface of the tooth embedded end face, the gear clutch will smoothly flow the transmission clutch from the bottom oil through the oil hole of the piston to the lower part of the valve and quickly eject it to the high surface. At this time, the transmission clutch compresses the spring and moves along the axial direction. The two clutches are in the "off" state, except that the rack moves in a straight line in the guide rail and the gear clutch engaged with it rotates, Other transmission parts have no action. The transmission clutch is in the state of preliminary return under the action of spring force. When the cylinder return stroke is completed, the transmission clutch quickly returns with the help of spring force, and the curved clutch returns to the "closed" state. After the stepping workpiece completes the action, send a signal to the solenoid valve, and the cylinder continues the next step action. Thus, the working requirements of step motion can be realized by cycling

2 design and calculation examples

realize step-by-step positioning transmission with a stroke of 254MM on the assembly line

2.1 cylinder and rack travel, gear clutch, transmission clutch and spindle revolutions

proposed cylinder travel l50mm, gear module m=2, gear clutch tooth number z=24. Then the gear clutch rotates for one circle, and the linear stroke of the rack is s= π mz=3.14 x 2 x 24=150.72mm, that is, the cylinder completes one stroke, and the gear clutch, transmission clutch and spindle rotate for one circle. During the design, the circumference of one revolution of the gear clutch should be close to the stroke of the selected cylinder, and the remaining small errors can be eliminated in the assembly to ensure that the positioning accuracy of the step will not be affected by the accumulation of errors

2.2 matching calculation of sprocket, pitch, speed ratio and step travel

the step travel required by the design is 254MM. If the sprocket pitch t=12.7 mm and the number of teeth of the conveying sprocket z3=40 are selected, the conveying sprocket rotates 20 teeth, and the linear conveying travel of its chain as an innovative energy storage technology bar is 254 mm. As long as the conveying sprocket rotates half a turn, it can meet the step travel requirements. It has been calculated that the speed of the main shaft is one revolution each time, and the number of main sprocket teeth on the main shaft zl=14. It is easy to conclude that as long as the number of transmission sprocket teeth z2=28, the required step stroke can be achieved when the speed ratio between the main shaft and the transmission shaft is l:2

2 . 3 Calculation of spring force

the design of spring should comprehensively consider the size of the overall dimension of the transmission clutch, the working stroke of the spring, the minimum pressing force required by the end faces of the two clutches and the tension of the cylinder. In the actual use process, the spring force should be adjusted with the adjusting screw sleeve according to the service condition of the gear clutch and transmission clutch to make the clutch stable and complete. In addition, the transmission clutch and the main shaft and key are equipped with clearance, and the roughness of the mating surface is required to be high to ensure axial movement

2.4 requirements of the design of gear clutch and transmission clutch for clutch design: simple structure, small overall size, stable combination, complete separation, accurate and reliable action, and dynamic fit between hole and keyway. The shape of the crank clutch is shown in Figure 2 and figure 3 respectively

3 automatic control

using magnetic cylinder as the actuator of action, combined with the use of programmable controller (PLC), it is easy to realize continuous automation of action, reduce the labor intensity of operators and improve productivity. Figure 4 is the schematic diagram of pneumatic control. In order to improve the running speed and ensure the productivity, the "return" direction is not throttled, and in order to prevent the instability of the workpiece caused by the fast speed of stepping operation, the one-way throttle valve is installed in the "push" direction to adjust the conveying speed

4 application example

the clutch stepping mechanism has been used in the stepping transportation of the independently selected project "pomelo automatic packaging shrinking machine" of the Department of science and technology of Fujian Province. The grapefruit in the fruit tray is stepped into the film wrapping and heat sealing cutting station by the clutch stepping mechanism according to the specified stroke. After finishing the wrapping and heat sealing and cutting, the pomelo enters the heat shrinking machine for heat shrinking, while the unprocessed pomelo enters the film wrapping and heat sealing and cutting station for processing. After a period of use, it has been proved that this stepping mechanism has the advantages of simple configuration, easy processing, stable operation, accurate positioning and easy automatic control. In order to reduce the instability of cylinder operation caused by pressure change in actual operation, the pressure regulating valve should be installed to stabilize the supply. Reducing the self weight of the vehicle as much as possible is the most effective way to reduce the air pressure

5 conclusion

the new clutch stepping mechanism has simple design, small volume and no complex machining parts. As long as the cylinder stroke, the number of gear teeth, chain pitch, the number of sprocket teeth and transmission speed ratio are simply calculated after the step process is determined, it can be matched, and there can be a variety of matching schemes for each step process. Even if the step process needs to be changed, it can be realized as long as the number of teeth of the driving sprocket and the transmission sprocket is adjusted, which is suitable for automatic step conveying with light load

the application shows that the clutch stepping mechanism is a relatively mature practical technology and has been put into practical use in production. The utility model patent was accepted by the State Intellectual Property Office in 2010

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