An improved hydraulic system for a press

Abstract

The invention discloses an improved hydraulic system for a press. It includes an oil tank, a low-pressure pump, a high-pressure pump, a small oil cylinder, a large oil cylinder, a reversing valve, an overflow valve, an accumulator, a solenoid valve, a check valve, and a hydraulically controlled check valve; the outlets of the low-pressure pump and the high-pressure pump are respectively connected to the rod chambers of the small oil cylinder and the large oil cylinder through the reversing valve; an overflow bypass connected to the oil tank with an accumulator and an overflow valve is provided on the connecting pipe between the small oil cylinder and the pump outlet; the rodless chamber of the large oil cylinder is connected to the oil tank through the reversing valve; a connecting pipeline with a check valve and a hydraulically controlled check valve is added between the rod chamber and the rodless chamber of the large oil cylinder; an oil pipeline with a solenoid valve is added to the outlets of the low-pressure pump and the high-pressure pump, and is connected to the control oil inlet of the hydraulically controlled check valve at the outlet of the rodless chamber of the large oil cylinder through the solenoid valve. The system can continuously return without stopping the large oil cylinder when the secondary mud is fed back, and only needs to start the high-pressure pump when the secondary mud is fed back, which can avoid the impact of frequent start and stop on the hydraulic components and improve the service life of the hydraulic components.

Description

Technical Field

[0001] The invention belongs to the technical field of sludge dehydration and relates to an improved hydraulic system of a press. Background Art

[0002] At present, there are two types of ultra-high pressure elastic presses, one is a spring press and the other is a cylinder press.

[0003] The hydraulic control system of the spring press is relatively simple, mainly using a high- and low-pressure dual-pump system. During low-pressure fast forward, dual pumps are used to supply oil. At this time, the forward speed of the oil cylinder is fast. During the pressing process, only the high-pressure pump works alone. In this way, the pressing pressure of the press is high and the power of the whole machine is small.

[0004] For the existing oil cylinder press, its hydraulic system is more complicated, and it also adopts a high-low pressure dual pump system. Its hydraulic principle is as follows: Figure 1 As shown, in the initial state, the piston rod of the large oil cylinder 8 is in the retracted state (in the initial position A); when starting to work, that is, low-pressure fast forward, the low-pressure pump 1 and the high-pressure pump 2 are used to supply oil. The high-pressure pump 2 is responsible for supplying oil to the sealed small oil cylinder 7 and supplying oil to the large oil cylinder 8 for slow pressing during pressing; during the pressing process, the high-pressure pump 2 supplies oil to the large oil cylinder 8 for pressing, the small oil cylinder 7 is compressed by the large oil cylinder 8, and the oil in the small oil cylinder 7 returns to the oil tank through the overflow valve 5, and the overflow valve 5 maintains the sealing pressure of the small oil cylinder 7; when the piston rod of the large oil cylinder 8 is extended to the final position C of pressing, the pressing process is completed; however, when the press needs to feed mud for the second time at the end of pressing, the large oil cylinder 8 needs to retreat to the locking mud feeding position B, and at the same time, the small oil cylinder 7 must be extended to maintain the mud feeding sealing pressure; but because the pressure of the small oil cylinder 7 is higher when providing sufficient sealing force, and the large oil cylinder 8 needs to return when returning The pressure is relatively low, so when the large oil cylinder 8 returns, the high-pressure pump 2 cannot charge the small oil cylinder 7 at the same time, which results in the secondary mud return process cannot be carried out continuously; the usual way to solve the above problem is: a bypass with an overflow valve 5 and an accumulator 6 is provided on the oil pipeline connecting the small oil cylinder 7 with the outlets of the low-pressure pump 1 and the high-pressure pump 2; the bypass with the overflow valve 5 and the accumulator 6 is connected to the oil tank; when the pressure of the small oil cylinder 7 is lower than the set value, the large oil cylinder 8 stops, and the high-pressure pump 2 charges the accumulator 6. When the pressure of the accumulator 6 reaches the set pressure, the large oil cylinder 8 retreats again, and the small oil cylinder 7 relies on the oil pressure provided by the accumulator 6 to extend a certain distance; when the pressure of the accumulator 6 drops to the set value, the large oil cylinder 8 must be stopped again to allow the high-pressure pump 2 to charge the accumulator 6 again; wherein, the charging and pressure relief of the small oil cylinder 7 and the forward and backward movement of the large oil cylinder 8 are controlled by the reversing valves 3 and 4.

[0005] In summary, the existing hydraulic system of the cylinder press has the following defects: it cannot return continuously when returning after the second mud feeding, and the large cylinder needs to stop and wait for the small cylinder accumulator to be pressurized. It can continue to retreat after the pressure reaches the set value; when returning after the second mud feeding, the low-pressure pump 1 and the high-pressure pump 2 need to be started at the same time; frequent starting and stopping will have an impact on the hydraulic components and affect the service life of the hydraulic components. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an improved press hydraulic system which can continuously return without stopping the large oil cylinder during the secondary mud feeding and returning, and only needs to start the high-pressure pump during the secondary mud feeding and returning, thereby avoiding the impact of frequent starting and stopping on the hydraulic components and prolonging the service life of the hydraulic components.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] The improved hydraulic system of the press comprises an original oil tank, a low-pressure pump, a high-pressure pump, a small oil cylinder, a large oil cylinder, a first reversing valve, a second reversing valve, a relief valve, and an accumulator; and further comprises an additional electromagnetic valve, a one-way valve, and a hydraulically controlled one-way valve; the piston rods of the small oil cylinder and the large oil cylinder are located on the same axis, and when the piston rod of the large oil cylinder is located between the starting position and the locking mud feeding position, the piston rods of the small oil cylinder and the large oil cylinder are not in contact; when the piston rod of the large oil cylinder is pushed When the position between the locked mud inlet position and the end of the squeezing is reached, the piston rods of the small oil cylinder and the large oil cylinder are in contact; the inlets of the low-pressure pump and the high-pressure pump are connected to the oil tank; the outlet of the low-pressure pump is connected to the outlet of the high-pressure pump; the outlets of the low-pressure pump and the high-pressure pump are divided into two paths, one is connected to the small oil cylinder through the first reversing valve, and the other is connected to the rod chamber of the large oil cylinder through the second reversing valve; the oil pipeline connecting the small oil cylinder with the outlets of the low-pressure pump and the high-pressure pump is provided with an overflow bypass connected to the oil tank, and the overflow bypass An accumulator and a relief valve are provided. The accumulator is arranged in front of the relief valve, and the outlet of the relief valve is connected to the oil tank; the rodless chamber of the large oil cylinder is connected to the oil tank via a second reversing valve; a connecting pipe is added between the rod chamber and the rodless chamber of the large oil cylinder, and a check valve and a hydraulically controlled check valve are added to the connecting pipe; the inlet of the hydraulically controlled check valve is connected to the rodless chamber of the large oil cylinder, and the outlet of the hydraulically controlled check valve is connected to the rod chamber of the large oil cylinder through the check valve; at the outlets of the low-pressure pump and the high-pressure pump In addition, an oil pipeline is added, and a solenoid valve is added to the oil pipeline, which is connected to the control oil inlet of the hydraulically controlled one-way valve at the rodless cavity outlet of the large oil cylinder through the solenoid valve (when the solenoid valve is energized, the P inlet of the solenoid valve opens, and the oil at the outlet of the high-pressure pump enters through the P inlet of the solenoid valve and comes out through the A outlet to reach the control oil inlet of the hydraulically controlled one-way valve at the rodless cavity outlet of the large oil cylinder; when there is control oil pressure at the control oil inlet of the hydraulically controlled one-way valve, the hydraulically controlled one-way valve opens).

[0009] Furthermore, an overflow bypass connected to the oil tank (capable of overflowing back to the oil tank) is additionally provided at the outlet of the hydraulically controlled one-way valve, and an overflow valve is additionally provided on the overflow bypass.

[0010] Furthermore, the solenoid valve is a two-position four-way solenoid valve; it has four ports, P, T, A, and B, its P inlet is connected to the high-pressure pump outlet, its A port is connected to the control oil inlet of the hydraulically controlled one-way valve, and its T outlet is connected to the oil tank.

[0011] Furthermore, a pressure relief bypass connected to the oil tank (which can release pressure and return to the oil tank) is added to the T outlet of the solenoid valve (when the solenoid valve is powered off, the P inlet of the solenoid valve is closed, the hydraulically controlled one-way valve is closed, and the control oil on the pipeline connecting the solenoid valve and the hydraulically controlled one-way valve enters from the A port of the solenoid valve and exits from the T outlet, and the pressure is released and returned to the oil tank).

[0012] Furthermore, the first reversing valve and the second reversing valve are three-position four-way electromagnetic reversing valves, which have four ports: P, T, A, and B.

[0013] Further, the P inlet of the first reversing valve is connected to the outlet of the high-pressure pump, the A outlet thereof is connected to the small oil cylinder, the B inlet thereof is connected to the small oil cylinder, and the T outlet thereof is connected to the oil tank.

[0014] Furthermore, the P inlet of the second reversing valve is connected to the outlet of the high-pressure pump, and the A outlet of the second reversing valve is connected to the rod chamber of the large oil cylinder.

[0015] Further, the B inlet of the second reversing valve is connected to the rodless chamber of the large oil cylinder, and the T outlet of the second reversing valve is connected to the oil tank.

[0016] Beneficial effects of the present invention:

[0017] Compared with the prior art, the improved hydraulic system of the press of the present invention has the following advantages:

[0018] 1. When returning from the second mud feeding, it can return continuously without the need to stop the large cylinder and wait for the small cylinder accumulator to be pressurized. After the pressure reaches the set value, it continues to retreat, which can save time and improve efficiency.

[0019] 2. When the mud is returned for the second time, the low-pressure pump 1 does not need to be started, and only the high-pressure pump 2 needs to be started, and the small cylinder 7 pushes the large cylinder 8 to return, saving energy.

[0020] 3. It can avoid the impact of frequent starting and stopping on hydraulic components and prolong the service life of hydraulic components. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the hydraulic principle diagram of the existing hydraulic system of the cylinder press;

[0022] Figure 2 It is a hydraulic principle diagram of an improved hydraulic system of a press according to the present invention.

[0023] In the figure: 1. low-pressure pump; 2. high-pressure pump; 3. first reversing valve (three-position four-way solenoid reversing valve); 4. second reversing valve (three-position four-way solenoid reversing valve); 5. relief valve; 6. accumulator; 7. small oil cylinder; 8. large oil cylinder; 9. check valve; 10. hydraulically controlled check valve; 11. relief valve; 12. solenoid valve (two-position four-way solenoid valve);

[0024] A. Starting position; B. Locking mud feeding position; C. End of pressing position. DETAILED DESCRIPTION

[0025] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0026] Example

[0027] like Figure 2 As shown, an improved hydraulic system of a press of the present invention comprises an original oil tank, a low-pressure pump 1, a high-pressure pump 2, a first reversing valve 3, a second reversing valve 4, a relief valve 5, an accumulator 6, a small oil cylinder 7, and a large oil cylinder 8; it also comprises an additional one-way valve 9, a hydraulic one-way valve 10, a relief valve 11, and a solenoid valve 12; the piston rods of the small oil cylinder 7 and the large oil cylinder 8 are located on the same axis, and when the piston rod of the large oil cylinder 8 is located between the starting position A and the locking mud feeding position B, the small oil cylinder 7 is not in contact with the piston rod of the large oil cylinder 8; when the piston rod of the large oil cylinder 8 is pushed between the locking mud entry position B and the pressing end position C, the piston rod of the small oil cylinder 7 is in contact with the large oil cylinder 8; the inlet of the low-pressure pump 1 and the high-pressure pump 2 are connected to the oil tank; the outlet of the low-pressure pump 1 is connected to the outlet of the high-pressure pump 2; the outlets of the low-pressure pump 1 and the high-pressure pump 2 are divided into two paths, one is connected to the small oil cylinder 7 through the first reversing valve 3, and the other is connected to the rod chamber of the large oil cylinder 8 through the second reversing valve 4.

[0028] The first reversing valve 3 and the second reversing valve 4 are both three-position four-way electromagnetic reversing valves, which have four ports: P, T, A, and B.

[0029] The P inlet of the first reversing valve 3 is connected to the outlet of the high-pressure pump 2, the A outlet thereof is connected to the small oil cylinder 7, the B inlet thereof is connected to the small oil cylinder 7, and the T outlet thereof is connected to the oil tank.

[0030] The P inlet of the second reversing valve 4 is connected to the outlet of the high-pressure pump 2, and the A outlet of the second reversing valve 4 is connected to the rod chamber of the large oil cylinder 8. The B inlet of the second reversing valve 4 is connected to the rodless chamber of the large oil cylinder 8, and the T outlet of the second reversing valve 4 is connected to the oil tank.

[0031] When the oil is fed in, the high-pressure pump 2 supplies oil to the small oil cylinder 7 and seals it (when supplying oil, the oil at the outlet of the high-pressure pump 2 enters through the P inlet of the first reversing valve 3, comes out through the A outlet, and reaches the small oil cylinder 7); when squeezing, the high-pressure pump 2 supplies oil to the large oil cylinder 8 for slow squeezing; the oil pipeline connecting the small oil cylinder 7 with the outlets of the low-pressure pump 1 and the high-pressure pump 2 is provided with an overflow bypass connected to the oil tank (which can overflow back to the oil tank), and the overflow bypass is provided with an overflow valve 5 and an accumulator 6, and the accumulator 6 is arranged in front of the overflow valve 5 (at the inlet of the overflow valve 5), and the outlet of the overflow valve 5 is connected to the oil tank; the rodless chamber of the large oil cylinder 8 is connected to the oil tank through the second reversing valve 4. The rodless chamber of the large oil cylinder 8 is connected to the oil tank (the rodless chamber of the large oil cylinder 8 is connected to the B inlet of the second reversing valve 4, and the T outlet of the second reversing valve 4 is connected to the oil tank); during the squeezing process, the high-pressure pump 2 supplies oil to the rodless chamber of the large oil cylinder 8 for squeezing (when supplying oil, the oil at the outlet of the high-pressure pump 2 enters through the P inlet of the second reversing valve 4, and comes out of the B outlet, to reach the rodless chamber of the large oil cylinder 8; when squeezing, the oil in the rod chamber of the large oil cylinder 8 enters through the A inlet of the second reversing valve 4, and comes out of the T outlet, and returns to the oil tank; the small oil cylinder 7 is compressed by the large oil cylinder 8, and the oil in the small oil cylinder 7 returns to the oil tank through the overflow valve 5, and the overflow valve 5 maintains the sealing pressure of the small oil cylinder 7).

[0032] The improvement of the improved hydraulic system of the press of the present invention lies in that: a connecting pipe is added between the rod chamber and the rodless chamber of the large oil cylinder 8, and a one-way valve 9 and a hydraulically controlled one-way valve 10 are added to the connecting pipe; the inlet of the hydraulically controlled one-way valve 10 is connected to the rodless chamber of the large oil cylinder 8, and the outlet of the hydraulically controlled one-way valve 10 is connected to the rod chamber of the large oil cylinder 8 through the one-way valve 9; an oil pipeline is also added at the outlet of the low-pressure pump 1 and the high-pressure pump 2, and a solenoid valve 12 is added to this oil pipeline, and the outlets of the low-pressure pump 1 and the high-pressure pump 2 are connected to the control oil inlet of the hydraulically controlled one-way valve 10 at the outlet of the rodless chamber of the large oil cylinder 8 through the solenoid valve 12 (when the solenoid valve 12 is energized, the P inlet of the solenoid valve 12 is opened, and the oil at the outlet of the high-pressure pump 2 enters through the P port of the solenoid valve 12 and comes out through the A port to reach the rodless chamber of the large oil cylinder 8 The hydraulically controlled one-way valve 10 at the cavity outlet controls the oil inlet. At this time, there is a controlled oil pressure at the control oil inlet of the hydraulically controlled one-way valve 10, and the hydraulically controlled one-way valve 10 is opened); an overflow bypass connected to the oil tank (which can overflow back to the oil tank) is added at the outlet of the hydraulically controlled one-way valve 10, and an overflow valve 11 is added to the overflow bypass (after the hydraulically controlled one-way valve 10 is opened, the rod cavity and the rodless cavity of the large oil cylinder 8 are connected through the one-way valve 9 to form a differential system. At the same time, the high-pressure pump 2 pressurizes the small oil cylinder 7, and the small oil cylinder 7 extends to push the large oil cylinder 8 back. A part of the oil in the rodless cavity of the large oil cylinder 8 is supplemented to the rod cavity of the large oil cylinder 8 through the one-way valve 9, and the excess oil is returned to the oil tank through the overflow valve 11. Adjusting the overflow valve 11 can adjust the pressure of the small oil cylinder 7, thereby adjusting the mud sealing force).

[0033] The solenoid valve 12 is a two-position four-way solenoid valve; it has four ports P, T, A, and B, its P inlet is connected to the outlet of the high-pressure pump 2, its A port is connected to the control oil inlet of the hydraulically controlled one-way valve 10, and its T outlet is connected to the oil tank.

[0034] A pressure relief bypass connected to the oil tank (which can release pressure and return to the oil tank) is added to the outlet of the solenoid valve 12 (when the solenoid valve 12 is powered off, the P inlet of the solenoid valve 12 is closed. At this time, there is no control oil pressure at the control oil inlet of the hydraulically controlled one-way valve 10, and the hydraulically controlled one-way valve 10 is closed. The control oil on the pipeline connecting the solenoid valve 12 and the hydraulically controlled one-way valve 10 enters from the A port of the solenoid valve 12 and exits from the T outlet, and the pressure is released and returned to the oil tank).

[0035] The working process of the improved hydraulic system of the squeezer of the present invention is as follows:

[0036] In the initial state, the piston rod of the large oil cylinder 8 is in a retracted state (in the initial position A); when starting to work, that is, when the low pressure is fast-forwarded, the low-pressure pump 1 and the high-pressure pump 2 supply oil at the same time, and the piston rod of the large oil cylinder 8 extends quickly; when the piston rod of the large oil cylinder 8 is extended to the locked mud feeding position B, all electrical appliances are powered off, and the press enters the mud feeding state; after the mud feeding is completed, it enters the squeezing process; during the squeezing process, the high-pressure pump 2 is used to supply oil to the large oil cylinder 8 for squeezing, and the small oil cylinder 7 is compressed by the large oil cylinder 8, and the oil in the small oil cylinder 7 returns to the oil tank through the overflow valve 5, and the overflow valve 5 maintains the sealing pressure of the small oil cylinder 7; when the piston rod of the large oil cylinder 8 is extended to the end position C of squeezing, the squeezing process is completed; when a second mud feeding is required after the squeezing is completed, the solenoid valve 12 is energized to control the hydraulic control one-way valve 10 to be turned on, and the rod chamber and the rodless chamber of the large oil cylinder 8 are connected through the one-way valve 9 to form a differential system. 7 is pressurized, the small oil cylinder 7 extends out, and pushes the large oil cylinder 8 back. A part of the oil in the rodless cavity of the large oil cylinder 8 is supplemented to the rod cavity, and the excess oil returns to the oil tank through the overflow valve 11. Adjusting the overflow valve 11 can adjust the pressure of the small oil cylinder 7, thereby adjusting the mud feeding sealing force; when the large oil cylinder 8 returns to the locked mud feeding position B, the high-pressure pump 2 and the solenoid valve 12 are powered off, and the secondary mud feeding state is entered; after the secondary mud feeding is completed, it enters the secondary squeezing process, and this secondary squeezing process is the same as the previous squeezing process; after the secondary squeezing process is completed, it enters the plate frame opening process, in which the return from the squeezing end position C to the locked mud feeding position B is the same as the secondary mud feeding return process; after reaching the locked mud feeding position B, the low-pressure pump 1 is started, and the high-pressure pump 2 supplies oil to the rod cavity of the large oil cylinder 8 at the same time, and the large oil cylinder 8 quickly returns to the starting position A, a complete working cycle ends, and waits for the next working cycle to start.

[0037] Compared with the prior art, the improved hydraulic system of the press of the present invention has the following advantages:

[0038] 1. When returning from the second mud feeding, it can return continuously without the need to stop the large cylinder and wait for the small cylinder accumulator to be pressurized. After the pressure reaches the set value, it continues to retreat, which can save time and improve efficiency.

[0039] 2. When the mud is returned for the second time, the low-pressure pump 1 does not need to be started, and only the high-pressure pump 2 needs to be started, and the small cylinder 7 pushes the large cylinder 8 to return, saving energy.

[0040] 3. It can avoid the impact of frequent starting and stopping on hydraulic components and prolong the service life of hydraulic components.

Claims

1. An improved hydraulic system for a press, characterized in that: It includes the original oil tank, low-pressure pump, high-pressure pump, small oil cylinder, large oil cylinder, first reversing valve, second reversing valve, overflow valve I, accumulator; also includes additional solenoid valve, one-way valve, hydraulic one-way valve, overflow valve II; the piston rods of the small oil cylinder and the large oil cylinder are located on the same axis, when the piston rod of the large oil cylinder is between the starting position and the locked mud feeding position, the piston rods of the small oil cylinder and the large oil cylinder are not in contact; when the piston rod of the large oil cylinder is pushed to between the locked mud feeding position and the end position of squeezing, the piston rods of the small oil cylinder and the large oil cylinder are in contact; the inlet of the low-pressure pump and the high-pressure pump are connected to the oil tank; the outlet of the low-pressure pump is connected to the outlet of the high-pressure pump; the outlets of the low-pressure pump and the high-pressure pump are divided into two paths, one is connected to the small oil cylinder through the first reversing valve, and the other is connected to the rod cavity of the large oil cylinder through the second reversing valve. Connect; an overflow bypass connected to the oil tank is provided on the oil pipeline connecting the small oil cylinder with the outlet of the low-pressure pump and the high-pressure pump, and an accumulator and an overflow valve I are provided on the overflow bypass, the accumulator is arranged in front of the overflow valve I, and the outlet of the overflow valve I is connected to the oil tank; the rodless chamber of the large oil cylinder is connected to the oil tank via a second reversing valve; a connecting pipe is added between the rod chamber and the rodless chamber of the large oil cylinder, and a check valve and a hydraulically controlled check valve are added to the connecting pipe; the inlet of the hydraulically controlled check valve is connected to the rodless chamber of the large oil cylinder, and the outlet of the hydraulically controlled check valve is connected to the rod chamber of the large oil cylinder through the check valve; an oil pipeline is also added at the outlet of the low-pressure pump and the high-pressure pump, and an electromagnetic valve is added to the oil pipeline, which is connected to the control oil inlet of the hydraulically controlled check valve at the outlet of the rodless chamber of the large oil cylinder through the electromagnetic valve; An overflow bypass connected to the oil tank is added at the outlet of the hydraulically controlled one-way valve, and an overflow valve II is added to the overflow bypass; The solenoid valve is a two-position four-way solenoid valve; it has four ports, P, T, A, and B, its P inlet is connected to the outlet of the high-pressure pump, and its A port is connected to the control oil inlet of the hydraulically controlled one-way valve; when the solenoid valve is powered on, the P inlet of the solenoid valve opens, and the hydraulically controlled one-way valve opens; when the solenoid valve is powered off, the P inlet of the solenoid valve closes, and the hydraulically controlled one-way valve closes; The first reversing valve and the second reversing valve are three-position four-way electromagnetic reversing valves, which have four ports: P, T, A and B.

2. The improved hydraulic system of a press as claimed in claim 1, characterized in that: A pressure relief bypass connected to the oil tank is additionally provided at the T outlet of the solenoid valve.

3. The improved hydraulic system of a press as claimed in claim 1, characterized in that: The P inlet of the first reversing valve is connected to the outlet of the high-pressure pump, the A outlet thereof is connected to the small oil cylinder, the B inlet thereof is connected to the small oil cylinder, and the T outlet thereof is connected to the oil tank.

4. The improved hydraulic system of a press as claimed in claim 1, characterized in that: The P inlet of the second reversing valve is connected to the outlet of the high-pressure pump, and the A outlet of the second reversing valve is connected to the rod chamber of the large oil cylinder.

5. The improved hydraulic system of a press as claimed in claim 1, characterized in that: The B inlet of the second reversing valve is connected to the rodless chamber of the large oil cylinder, and the T outlet of the second reversing valve is connected to the oil tank.

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