Design and transmission principle of full hydraulic cutting
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Hydraulic and control technology, with its unique talent, was applied to the digital display and program-controlled paper cutter press mechanism in the 1990s. With fast, safe, smooth movement, high paper pressure, low noise and automatic control, it has won the favor in the domestic and foreign markets. "If you want to do something good, you must first sharpen its tools." From the current domestic digital display, program-controlled paper cutters, the transmission structure analysis: the cutting mechanism is a worm gear transmission, the structure is complex, the transmission efficiency is low (50%), Insufficient utilization of hydraulic systems. Based on the above analysis, we have conducted long-term research and discussion, designed the paper cutter pressing and cutting work program as a full hydraulic control system, which will improve the performance of the domestic paper cutter to a new level.
First, design requirements and basis
(1) Working principle.
1. Light-pressed paper→cutting→cutting knife returning position→pressing paper back to the position.
2. Action requirements.
1 The cutting knife is locked at the top dead center position.
2 cutting resistance to overload protection.
3 hands-on, safe, flexible and reliable.
4The cutting knife can stop when it moves to any position. There should be no continuous knife and obvious sliding knife.
5 operation can be pressed on the paper, single and continuous cutting movement.
(2) Main technical parameters.
According to the manufacturing standard of GB3902-83 hydraulic paper cutter, the width of the door is 920mm as an example. Paper pressing force 30000N, cutting resistance: According to the article "Testing and Analysis of Cutting Resistance" in the fifth issue of "Printing Technology" magazine in 1993, the linear cutting resistance of 120g/m2 double-sided coated paper is 15000N, and the height of paper is high. 120mm, cutting speed 40 times / min.
Second, the full hydraulic paper cutter drive principle
According to the design requirements of national standards, the schematic diagram of the drive schematic, action diagram and electromagnet action sequence of the full hydraulic paper cutter is as follows:
1. Hydraulic pump unloading:
Before cutting, start the system motor and drive the vane pump through the belt. The pressure oil is unloaded by the filter through the vane pump → pedal 2/2-way valve → 2/2-way solenoid valve.
2. Foot press operation:
When the foot pedal is stepped on, the two-position two-way valve is closed, and the solenoid valve 3YA is turned on. The pressure oil passes through the vane pump → 3YA → slide valve 4 → plunger speed increasing cylinder, so that the pressure paper is quickly moved down and pressurized. The pressure of the paper can be achieved by adjusting the pressure relay. The cutting force and unloading of the system can be achieved by adjusting the relief valve.
3. Single cutting action program:
1 Light-pressed paper: Press the double button in front of the workbench with both hands, the solenoid valve 2YA, 3YA energizes, and the electromagnetic pin pulls the pin. Pressure oil → 3YA → slide valve 4 → plunger speed increasing cylinder → swing arm 1 rotates, press paper and press it quickly onto the paper.
2 Pressurization: As the pressure of the system increases, the control pipeline moves the spool to the right, the area of the plunger is increased, and the paper pressing force meets the design standard requirements.
3 Cutting: At the same time, the pressure oil in the system control pipeline reverses the pressure relay, and the three-position four-way solenoid valve 6YA is turned on, and the 3YA is powered off. The pressure oil enters the right end of the cutting cylinder through the right end of 6YA, moves the piston to the left, pushes the swing arm 2, and drives the connecting rod cutting knife to cut to the bottom dead center along the cutting angle.
4 Cutting knife return position: When the cutting knife falls to the knife bar, touch the beginning of the stroke C2, so that 6YA is de-energized, 3YA, 5YA are energized, and the pressure oil enters the left cavity of the cutting cylinder through the reversing valve 5YA, so that the piston moves to the right. , the swing arm 2 is driven, and the connecting rod cutting knife returns to the origin.
5 Latch: The cutting knife returns to the origin, touches the travel switch C1, and the electromagnetic pin is powered off. The pin is inserted into the cutting body under the action of the spring to prevent the cutting knife from sliding down.
6 Pressing paper back to the position: the latch returns to the position, touches the travel switch C3, so that 2YA, 3YA is de-energized, and the plunger speed increasing cylinder is unloaded under the action of the pressure paper returning spring and the system returning oil, the slide valve 4 Returning to the position, the plunger speed increasing cylinder returns to the position, and the paper is pressed back to the position, and everything returns to normal.
7 The cutting knife stops in any position during the movement.
When the three-position four-way solenoid valve 6YA is turned on, the pressure oil enters the right end of the cutting cylinder through the valve, and the obstructing object blocks the photoelectric grating in the safe area in front of the working table during the downward movement of the cutting knife, and the photoelectric switch receives the information. The three-position four-way valve 6YA is de-energized, in the middle position, and the oil returning oil circuit is closed, so that the cutting knife can be in any position.
8 Overload protection: The cutting resistance and safety system of the paper are necessary conditions to ensure the normal operation of the machine. The relief valve in the system plays two main functions. First, the unit cuts the resistance overload protection—overflow, and second, the excess pressure oil overflows back to the tank.
4. Continuous cutting:
During continuous cutting, the index switch is turned to the continuous cutting position, and when the paper pressing return switch C4 is touched, the solenoid valves 2YA, 3YA are simultaneously turned on, thereby starting a new round of single times. Cut the exercise program.
Third, the hydraulic system design calculation
When the paper pressing force is 30000N, the cutting resistance is 20000N, the paper pressing height is 120mm, the moving parts are 10KN, the rectangular guide rail is used, the friction coefficient is f=0.1, and the average pumping speed is 21.2cm/s, the hydraulic pump flow rate and input power are obtained. Work pressure?
(1) 1. Cutting work pressure: when the arm and the arm are 1:1,
F push = F cut + F guide + F habit + F secret + F back
Check Table 1 P=4Mpa
2. Cutting cylinder inner diameter
Choose the inner diameter of the 70 cylinder.
3. Piston rod diameter: according to the cutting cylinder pressure 4MPa, check the table 2,
Take 0.6D = 0.6 × 70 = 42mm. Choose 45mm diameter.
(2) Determining the flow rate of the hydraulic pump: The cutting speed is known to be 21.2 cm, and there is a difference between the area of the piston rod. When the flow is constant, the movement of the piston is different.
1. Required flow rate of the cylinder:
Q1= A1=21.2( D2)=48.8L/min
Q2= A2=21.2[ (D2-d2)]=28.6L/min
The average flow rate of the cylinder is
q= = 38.7L/min
q pump = q · (1 + 10%) = 1.1 q = 42.67 = 43L / min
Hydraulic pump requires flow
2. Drag the motor power of the hydraulic pump.
Pump output power
Pq= ==3.37kw
Motor Power
P electricity = = = 3.94kw
Fourth, the effect analysis
The whole system has simple structure, high transmission efficiency, fast response, stable movement, automatic control of overload protection of the system, convenient operation and adjustment, safety, inferiority, low noise, compliance with and meet the requirements of manufacturing and cutting processes, and a wide range of Application prospects.