Chapter 4  Circuit Design of Air Pressure Control System

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4-1   Basic Steps of Circuit Design for Pneumatic System TOP 

Step 1: Draw a working diagramP137       
   

Step 2: Write the movement sequence of the pneumatic cylinder in the system

(1) Travel-step diagram      TOP       

(2)  Travel-time diagram (also known as time-travel diagramTOP       

Step 3:  Design the air pressure control circuit according to the function chart or control signal chart  TOP       
               
 

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Step 4: Create Component usage table TOP       

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     The air pressure control circuit discussed in this chapter is mainly based on the traditional pure pneumatic control. Its operating pressure is 3 to 8 kgf / cm2 , the output is between 0 to 3000 kgf, and the speed is between 0.5 to 1.5 m/sec . The following is Several commonly used pure pneumatic circuit design methods.

 Intuitive method.

 Cascade method.

 Cycle step method.

4-2   Intuitive method (Method or Intuition)   the TOP       

Signal processing method of this design embodiment has the following ways:
1. The  
standing-wave signal stagnation (Standing) mode : It is used for general signals. Installed at the end of the stroke of the pneumatic cylinder with two-way rollers to generate standing wave signals, as shown in Figure 4-8.

2. The  pulse signal overstroke (over travel) mode : It is used for interference signal. Installed on the inner side of the end of the stroke of the cylinder with a unidirectional roller. After touching it, it will generate pulse signal.             TOP 

Intuitive design of the pneumatic circuit can use the method of Figure 4-10 to performone by one       TOP  

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Examples 4-1 Milling work design TOP          

(a)  Draw a working diagram , as shown in Figure 4-11 .

 

 

(b)  Draw a motion picture , which is represented by a displacement time diagram, as shown in Figure 4-12 . At the same time, its exercise sequence is listed in abbreviation: A + B + AB-     TOP

(c)  Mapping the  air pressure circuit       TOP

Determine the operation method used by the limit switch  Unidirectional or bidirectional roller  : When the signal conflict on the two sides of the direction control element is caused, the interference signal needs to be processed into a pulse signal by overtravel ( that is, the limit switch must be unidirectional Roller and move inward ) . The remaining signal elements are actuated by two-way rollers. May be established below the interference analysis table analysis of    

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Example 4-2  rivet riveting machine pneumatic control circuit design        TOP

(a)  Working diagram

(b)  Displacement Time FIG TOP       

(c)  Pneumatic Circuit TOP       

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Example 4-3 Design of air pressure control loop for drilling. (a) Displacement time diagram.    TOP  

exercise sequence is: A + B slow + B- A-. 
   
 
       
 

  (b) Pneumatic Circuit  TOP       

      The interference signals are a1 and b0 . Change the single roller to move inward in overtravel mode.

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  Example 4-4 Design of a pneumatic control circuit for automatic drilling and unloading with single cycle operation and continuous processing cycle functions TOP        

  (a)  Working diagram

 

(b)  Displacement Time FIG TOP       

(c)  Pneumatic Circuit TOP       

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Example 4-5 Design of pressure control circuit for chemical cleaning the container. TOP        

(a)  Working diagram

(b)  Displacement Time FIG TOP       

(c)  Pneumatic Circuit TOP       

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4-3  Cascade Method TOP       

The  method of cascade uses the signal transfer action of the 4/2 ( or 5/2) bilateral pneumatic valve or reversing valve to enable complex control to ensure that only one signal is output per action:       

Take Figure 4-27 as an example:

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How to grade? TOP       

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Example 4-6  Try to design the following air pressure control circuit by cascade method.         TOP  

displacement time chart is shown in Figure 4-33 .       
 

Step List exercise sequence TOP       

Step Classification. 

Step   Draw the pressure conversion signal. 

Step   Draw the drive element, direction control element and limit switch positions and name them alphabetically.

 

Step List the signal flow and connect the relevant signals to complete the loop. TOP       

Example 4-7 Try to design the air pressure control circuit in the sequence of action diagram. TOP       

Example 4-8 Milling working displacement time of milling machine is shown in Figure 4-40. TOP       

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Example 4-9 The schematic diagram of the bead blasting work and the displacement steps of the casting are shown in Figure 4-43 and 44. TOP        

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Step   Connect the relevant signals to complete the circuit design. TOP       

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The displacement steps of Example 4-10 are shown in Figure 4-47. TOP        

The signal flow is: TOP

4-4  Cycle Step Control Circuit Design Method TOP       

Example 4-11 Printing logo continuously. Figure 4-51 is its schematic diagram. Figure 4-52 shows the displacement steps. TOP   

Step Find the signal flow. TOP   

Step Connect related signals and add auxiliary conditions to complete the circuit design.

Designed by maximum structure method: TOP   

Example 4-12  bent and punched clamp, Figure 4-56 is the schematic diagram of this work. Figure 4-57 is the displacement time chart. TOP   

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Step :  List exercise sequences. 
Step : Classification. TOP 

Step :   Draw the pressure conversion signal. 

Step :   Draw the drive elements, direction control elements and corresponding limit switch positions and name them in alphabetical form.     

 

Step Find the signal flow. TOP   

Step Connect the relevant signals, add auxiliary conditions  (B C speed control required,Manual and automatic selection) to complete the circuit design. TOP   

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GOTO    Chapter 5 Electrical-Pneumatic Control

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