Stamping equipment high-speed CNC press hydraulic system

    With the gradual accelerated development of China's industry in the direction of modernization, the gradual formation of the modern industrial system, the domestic market for high-speed stamping equipment demand is more and more urgent, and its performance requirements in all aspects are also increasingly high. At present, China almost does not have the ability to independently produce high-speed stamping equipment hydraulic system, resulting in the production of stamping equipment in China is very high cost, and imported hydraulic system can not be well adapted to the actual situation in our country, so according to the actual situation in our country at present, the development of high-speed CNC punching presses for our country's national conditions of the hydraulic system is an urgent need to solve the problem.high speed punch press

   1.Overview of stamping equipment
    To make greater development of stamping technology, have more advanced stamping equipment is a necessary prerequisite, stamping system is an important part of the stamping equipment, is currently the world's stamping press system is mainly used in mechanical and hydraulic, mechanical is a more traditional stamping method, which is mainly through the crank press this equipment to realize the stamping, the crank press the main parts of the ram, crankshaft, connecting rod and so on. Hydraulic press apply hydraulic transmission system to realize the stamping function, its basic working principle for the YA1 current through the hydraulic oil under the action of the pump through the electromagnetic reversing valve into the lower chamber of the hydraulic cylinder, then the hydraulic oil in the upper chamber of the hydraulic cylinder will flow back to the tank through the check valve 3, the electromagnetic reversing valve 2, the slider in the piston under the drive upward movement; at this time on the YA2 energized, the electromagnetic reversing valve 2, the right position begins to Work, the slider will be driven by the piston downward movement, stamping the workpiece to achieve the stamping function.high speed punch press

Second, the design of CNC high-speed punch press hydraulic system
2.1 Analysis of the working conditions of the system and the determination of the program
The design of the high-speed press can not only stamping metal, but also capable of punching processing. On the workpiece stamping type, the slider quickly down, contact with the workpiece, the slider speed is reduced, but the pressure becomes larger to ensure that the workpiece is accurately shaped, after completing the stamping process, the slider quickly rise. The hydraulic system to achieve the purpose of rapid stamping, the design of the system's circuit uses an accumulator + double pump oil supply + differential connection combination. Selected proportional servo directional valve as the control element of the press hydraulic system to meet the requirements of fast and frequent direction change when the system works. The following figure is the hydraulic system of high-speed numerical control press.
Schematic diagram.
1, motor 2, high-pressure high-flow pump 3, low-pressure low-flow pump 4, pressure gauge 5, filter 6, air filter 7, cooler 8, hydraulic directional valve 9, solenoid valve 10, 15. check valve 11, 16. accumulator 12, relief valve 13, proportional servo valve 14, hydraulic cylinder
From the above figure can be seen in the working principle of the system: proportional servo valve of the right work, pump 2 excluded from the hydraulic oil and pump 3 discharged after the hydraulic oil through the hydraulic reversing valve 8 together flow through the proportional servo valve, flow into the upper chamber of the hydraulic cylinder, at the same time, the cylinder chamber of the oil flow through the 8 and 13 two valves in turn, also flow into the upper chamber, which constitutes a differential circuit, the punch produces a downward fast movement. When the punch touches the workpiece, the pressure received increases and reaches the maximum bearing pressure of valve 8, the left position of valve 8 is turned on, the pump 3 stops working and the differential circuit is interrupted, at this time, the high-pressure oil discharged from the pump 2 flows into the upper cavity of the hydraulic rod through the valve 13, and the punch slowly moves downward to press the workpiece. Punching to the specified limit, SQ2 signal, proportional valve received a negative input voltage signal, the left position is connected, while the system pressure is automatically lowered, connected to the right position of the valve 8, pump 2 and pump 3 together will be pumped such as into the lower chamber of the hydraulic cylinder, the upper chamber of the
Oil flow through the valve 13 back to the tank, the punch in the piston driven by the rapid upward movement, up to this point is a working cycle of the whole process.
2.2 Basic working parameters of hydraulic system
The rated maximum working load of the system is F=200 Kn. The system is supplied by two pumps, the rated pressure of the low-pressure pump is 7 Mpa, and the rated pressure of the high-pressure pump is 31.5 Mpa.
Pa. The maximum stroke S of the press is 40mm, the stamping cycle changes with the stroke, when the stamping stroke is set to 12mm, the stamping cycle T is 0. 2s.
2s.
(1) Calculate the inner diameter of the cylinder barrel D. It is known that the maximum load of the system is 200KN, and the maximum pressure P is 0.8pn=25Mpa, and let the resistance f be 25KN, and according to the formula D ≥ 4 (Fmax+ f) pn, we get D=110mm.(2) The diameter of the piston rod d. The speed of the piston when it is downward is v1=4qnd2, and when it is upward, it is v2=4qT (D2-d2), and it is v2=4qT (D2-d2), and it is v2=4qT (D2-d2). Find the maximum value of v1+v2=V. It is found that 22D=d=77.8 when the piston takes the least time to complete one work cycle. So take d=80mm.(3) Pump displacement. In a working cycle, the oil out of the tank should be equal to its oil inlet, so a working cycle of the total flow Q = 8TDSf = 34.2 L/min, so the theoretical flow rate of the low-pressure pump qt2 = 30 L/min, the high-pressure pump for qt1 = 10L/min to set the rotation speed of the two pumps are 1500 r / min.
According to the formula qt = Vn, high-pressure pump displacement V1 = 6.7 mL / r, low-pressure pump displacement V2 = = 20 mL / r
According to the above calculation, the low-pressure pump decided to use the displacement V2 = 20 mL / r, rated pressure pn2 = 7 Mpa
GFZB-5 gear pump, high-pressure pump selection displacement V1 = 6.3 mL / r, rated pressure pn1 = 31.5 MPa GFZB-6 valve flow distribution axial plunger.
2.3 Speed calculation
Velocity checking is carried out under the condition that the stroke is 12 mm and the thickness of the stamping plate is 1 mm. When the piston is traveling downward v1=4(q1+ q2) T d2= 1
3.09 cm/s, when the piston upward v2 = 4 (q1 + q2) T (D2 - d2) = 14.68 cm/s, then the frequency is 4.25 HZ, that is, per minute
The workpiece can be stamped 265 times. It can be seen that when S=10mm, when stamping a workpiece with a thickness of 1mms, it is possible to realize the predetermined goal of f reaching more than 300/min.

Third, conclusion
In this paper, the hydraulic system of press machine is designed, using proportional servo directional control valve as the control element of the system, the pressure system according to the change of load
The pressure system is automatically adjusted according to the load change, and the design scheme of double pump alternating oil supply is adopted. Secondly, according to the requirements of the press, the stroke, cycle, frequency, pressure and other operating parameters are determined, and then the design and calculation of the hydraulic system is carried out.
Then the design calculates the data of the hydraulic cylinder, which is the main component of the hydraulic system, and finally, after checking and calculating, it is determined that the initial design goal can be realized.

high speed punch press