A hydraulic system for a sand making machine and its start-up adjustment method

Abstract

A hydraulic system for a sand making machine and its start-up adjustment method are disclosed, relating to the technical field of sand making machine equipment. The hydraulic system includes an oil tank, a hydraulic pump, a hydraulic control valve group, an accumulator valve platform, and a hydraulic cylinder. The hydraulic control valve group includes a solenoid directional valve for controlling the extension or retraction of the piston rod of the hydraulic cylinder, and a hydraulically controlled check valve for maintaining pressure after the rod chamber of the hydraulic cylinder is filled. The accumulator valve platform includes a rodless chamber circuit, a rod chamber circuit, and an accumulator, which is located on the rod chamber circuit and is used for pressure maintenance and overpressure protection. The start-up adjustment method includes: 1. Pressurizing the rod chamber of the hydraulic cylinder and the accumulator; 2. The accumulator is used for pressure maintenance and overpressure protection; 3. Pressurizing when the pressure drops during sand making machine operation and depressurizing when the pressure is too high; 4. Depressurizing before stopping the machine; 5. Retracting the moving roller during maintenance. This invention can solve the technical problems of existing sand making machines, such as large vibration, frequent start-stop, short lifespan, lack of standardization, and easy oil contamination.

Description

Technical Field

[0001] This invention relates to the field of sand making machine equipment technology, specifically to a hydraulic system for a sand making machine and its start-up adjustment method. Background Technology

[0002] Sand making machines are used for crushing operations in the sand and gravel industry. Their main function is to produce construction sand from pebbles, gravel, and granite. During operation, the material passes through the gap between the moving and fixed rollers and is crushed under the pressure of the two rollers. The piston rod of the hydraulic cylinder is connected to the moving roller arch, and the cylinder body is connected to the fixed roller arch, providing pressure to the two rollers. The hydraulic system controls the movement of the hydraulic cylinder, maintaining the gap and pressure between the rollers within a set range according to changes in working conditions. During operation, the sand making machine uses an accumulator assembly to stabilize the working pressure in the rod chamber of the hydraulic cylinder and absorb pressure pulsations and hydraulic shocks.

[0003] The valve assembly principle and structural design of existing sand making machine hydraulic systems are complex, with valves scattered and difficult to troubleshoot. The accumulator volume on the accumulator valve platform is designed for a single working condition. When the material condition, roller gap size, and output change, the accumulator maintains poor stability in the working pressure of the rod chamber of the hydraulic cylinder. This easily leads to large pressure fluctuations in the hydraulic system, resulting in large vibrations of the sand making machine, frequent start-ups and shutdowns of the hydraulic system, large impact forces on the hydraulic pipelines, and short service life. When the specifications of the sand making machine change, the accumulator valve platform cannot be universalized due to the mismatch of accumulator volumes. Due to high dust levels on site, oil contamination occurs, causing valve jamming, oil pump wear, and other malfunctions in the hydraulic system, resulting in low sand making machine operating rates. Summary of the Invention

[0004] The purpose of this invention is to provide a hydraulic system for a sand making machine and its start-up adjustment method, which can solve the technical problems of existing sand making machines, such as large vibration, frequent start-up and shutdown, short life, lack of universality, and easy oil contamination.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A hydraulic system for a sand making machine includes an oil tank, a hydraulic pump, a hydraulic control valve group, an accumulator valve platform, and a hydraulic cylinder.

[0007] The hydraulic control valve group includes a solenoid directional valve. Switching the solenoid directional valve can control the pressure oil output by the hydraulic pump to enter the first pressure oil circuit or the second pressure oil circuit, which is used to control the extension or retraction of the piston rod of the hydraulic cylinder. The second pressure oil circuit is also equipped with a hydraulically controlled check valve, which is used to maintain pressure after the rod chamber of the hydraulic cylinder is filled with fluid.

[0008] The accumulator valve platform includes a rodless chamber circuit, a rod chamber circuit, and an accumulator. The rodless chamber circuit connects the first pressure oil circuit to the rodless chambers of multiple hydraulic cylinders. The rod chamber circuit connects the second pressure oil circuit to the rod chambers of multiple hydraulic cylinders. The accumulator is located on the rod chamber circuit and is used for pressure holding and overpressure protection of the rod chambers of the hydraulic cylinders.

[0009] The oil tank has an oil suction side and an oil return side. The oil return side is equipped with an oil return filter to filter the hydraulic oil returning to the oil tank. A circulating filter cooling circuit is also provided between the oil suction side and the oil return side. The circulating filter cooling circuit is equipped with a circulating pump, a circulating filter and an air cooler in sequence. The circulating pump is used to draw hydraulic oil from the oil return side and pump it to the oil suction side. The circulating filter is used to filter the hydraulic oil drawn in by the circulating pump. The air cooler is used to cool down the hydraulic oil that has passed through the circulating filter.

[0010] Furthermore, the solenoid directional valve is a three-position four-way solenoid directional valve, and the neutral position function is H-type.

[0011] Furthermore, both the first and second pressure oil circuits are equipped with one-way throttle valves for adjusting the oil output of the first and second pressure oil circuits, preventing the hydraulic cylinders from moving too fast and causing multiple hydraulic cylinders to move asynchronously. The one-way throttle valve on the second pressure oil circuit is located after the hydraulic control check valve.

[0012] Furthermore, the second pressure oil circuit is equipped with an unloading circuit after the one-way throttle valve for overpressure protection of the rod chamber of the hydraulic cylinder. The unloading circuit includes a throttle valve and a solenoid ball valve connected in series. The throttle valve is used to limit the pressure relief speed of the rod chamber of the hydraulic cylinder.

[0013] Furthermore, the unloading circuit also includes an unloading relief valve and an unloading ball valve. Both the unloading relief valve and the unloading ball valve are connected in parallel with the throttle valve and the solenoid ball valve connected in series. The unloading relief valve is used for overpressure protection of the rod chamber of the hydraulic cylinder, and the unloading ball valve is used for manual pressure relief of the rod chamber of the hydraulic cylinder.

[0014] Furthermore, both the first and second pressure oil circuits are equipped with pressure oil circuit ball valves for pressure adjustment, pressure testing, and fault handling of the hydraulic system within the hydraulic station. The pressure oil circuit ball valve on the second pressure oil circuit is located after the unloading circuit.

[0015] Furthermore, the accumulator valve platform includes a pressure sensor installed on the rod chamber circuit, which is used to monitor the oil pressure in the rod chamber of the hydraulic cylinder in real time. When the oil pressure changes, it can pressurize or depressurize the circuit according to a preset program, or shut down the hydraulic system or the sand making machine.

[0016] Furthermore, the accumulator valve platform includes a pressure relief circuit located on the rod chamber circuit, and the pressure relief circuit is equipped with a pressure relief ball valve for manual pressure relief of the rod chamber of the hydraulic cylinder.

[0017] Furthermore, an isolation ball valve is provided at the connection between the accumulator and the rod chamber circuit to isolate the accumulator in case of damage or standby.

[0018] A method for adjusting the start-up of a sand making machine, based on the aforementioned hydraulic system, includes the following steps: S1. When the sand making machine starts working, start the hydraulic pump, switch the solenoid directional valve to allow the pressurized oil to enter the rod chamber of the hydraulic cylinder through the second pressure oil circuit and the rod chamber circuit. After the hydraulic cylinder rod chamber and accumulator are pressurized to the preset target, shut down the hydraulic pump, de-energize the solenoid directional valve to return to the neutral position, and start the sand making machine to carry out production operations. S2. When the sand making machine is working normally, the hydraulic pump and solenoid valve are de-energized. Under the action of the hydraulic cylinder, the moving roller of the sand making machine maintains the preset pressure and roller gap with the fixed roller. The accumulator is used for pressure holding and overpressure protection of the rod chamber of the hydraulic cylinder. S3. Pressure adjustment during sand making machine operation: When the pressure in the rod chamber of the hydraulic cylinder drops below the minimum preset value during sand making machine operation, the hydraulic cylinder rod chamber pressurization action is executed. The hydraulic pump is started, and the solenoid directional valve is switched to allow pressurized oil to enter the hydraulic cylinder rod chamber through the second pressure oil circuit and the rod chamber circuit. After the hydraulic cylinder rod chamber and accumulator are pressurized to the preset target, the hydraulic pump is shut off, and the solenoid directional valve is de-energized and returns to the neutral position. When the pressure in the rod chamber of the hydraulic cylinder is higher than the maximum preset value during the operation of the sand making machine, the hydraulic cylinder rod chamber pressure relief action is executed, the solenoid ball valve is activated, and the solenoid ball valve is closed after the pressure in the rod chamber of the hydraulic cylinder drops to the preset range. S4. The sand making machine stops normally. After crushing stops, the hydraulic cylinder rod chamber is depressurized and the solenoid ball valve is activated. After the pressure in the hydraulic cylinder rod chamber drops below 1MPa, the solenoid ball valve is closed and the sand making machine stops. S5. When the moving roller retracts and the sand making machine needs maintenance, the hydraulic cylinder rodless chamber is pressurized. The hydraulic pump is started, and the solenoid directional valve is switched so that the pressurized oil enters the rodless chamber of the hydraulic cylinder through the first pressure oil circuit and the rodless chamber circuit. At the same time, the hydraulic cylinder rod chamber and accumulator are depressurized. After the moving roller retracts to the preset position, the hydraulic pump is turned off, and the solenoid directional valve is de-energized and returns to the neutral position.

[0019] By adopting the above technical solution, the present invention has the following beneficial effects: 1. This invention integrates the overload protection circuit with the cylinder control circuit, optimizes the hydraulic valve group principle and hydraulic station structure, making the hydraulic station structure compact and easier to maintain; 2. The present invention arranges the accumulator valve platform nearby, which makes the shock absorption effect more sensitive and improves the stability of the working pressure of the rod chamber of the hydraulic cylinder; 3. In this invention, the accumulator volume and charging pressure can be matched according to the material characteristics and output, adapting to various working conditions and possessing good versatility; 4. This invention adds a circulating filter cooling circuit to the oil tank to improve the cleanliness of the oil, solving the problem of high failure rate of hydraulic system caused by high dust on site, and improving the operating rate of sand making machine. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the sand making machine in this invention.

[0021] Figure 2 This is a schematic diagram of the hydraulic system in this invention.

[0022] Attached diagram descriptions: 1. Oil tank; 11. Suction side; 12. Return side; 13. Return filter; 14. Circulation pump; 15. Circulation filter; 16. Air cooler; 2. Hydraulic pump; 21. Electric motor; 22. High-pressure filter; 23. Outlet relief valve; 24. Outlet check valve; 25. Outlet pressure gauge; 3. Hydraulic cylinder; 31. Piston rod; 32. Cylinder body; 41. Solenoid directional valve; 42. Hydraulic check valve; 43. One-way throttle. 44. Pressure oil circuit ball valve; 45. Oil circuit pressure gauge; 51. First pressure oil circuit; 52. Second pressure oil circuit; 61. Rodless chamber circuit; 62. Rod chamber circuit; 63. Accumulator; 64. Pressure sensor; 65. Pressure relief ball valve; 66. Isolation ball valve; 71. Throttle valve; 72. Solenoid ball valve; 73. Unloading relief valve; 74. Unloading ball valve; 81. Moving roller; 82. Fixed roller; 83. Moving roller arch; 84. Fixed roller arch. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the features and performance of a hydraulic system for a sand making machine and its start-up adjustment method are further described in detail below with reference to the accompanying drawings and embodiments.

[0024] Please see the appendix Figures 1-2 A hydraulic system for a sand making machine includes an oil tank 1, a hydraulic pump 2, a hydraulic control valve group, an accumulator valve platform, and hydraulic cylinders 3. The number of hydraulic cylinders 3 may vary depending on the specifications of different equipment. In this embodiment, the sand making machine is provided with two hydraulic cylinders 3, one on each side of the grinding roller of the sand making machine. The piston rod 31 of the hydraulic cylinder 3 is connected to the moving roller arch frame 83, and the cylinder body 32 is connected to the fixed roller arch frame 84.

[0025] The hydraulic control valve assembly includes a solenoid directional valve 41. Switching the solenoid directional valve 41 controls the pressure oil output from the hydraulic pump 2 to enter either the first pressure oil circuit 51 or the second pressure oil circuit 52, which is used to control the extension or retraction of the piston rod 31 of the hydraulic cylinder 3. The second pressure oil circuit 52 is also equipped with a hydraulically controlled check valve 42 for maintaining pressure after the rod chamber of the hydraulic cylinder is filled with fluid. Specifically, the solenoid directional valve 41 is a three-position four-way solenoid directional valve 41, and the neutral position function is H-type. The P port of the solenoid directional valve 41 is connected to the oil outlet of the hydraulic pump 2, the A port is connected to the first pressure oil circuit 51, the B port is connected to the second pressure oil circuit 52, and the T port returns to the return side 12 of the oil tank 1.

[0026] Both the first pressure oil circuit 51 and the second pressure oil circuit 52 are equipped with one-way throttle valves 43 for regulating the oil flow from the first pressure oil circuit 51 and the second pressure oil circuit 52. This prevents the hydraulic cylinders 3 from moving too fast, causing multiple hydraulic cylinders 3 to move asynchronously. The one-way throttle valve 43 on the second pressure oil circuit 52 is located after the hydraulically controlled one-way valve 42. A pressure gauge 45 is also provided after the one-way throttle valve 43 in the second pressure oil circuit 52 to display the pressure in the rod chamber of the hydraulic cylinder.

[0027] The second pressure oil circuit 52 is equipped with an unloading circuit after the one-way throttle valve 43 for overpressure protection of the rod chamber of the hydraulic cylinder. The unloading circuit includes a throttle valve 71 and a solenoid ball valve 72 connected in series. The throttle valve 71 is used to limit the pressure relief speed of the rod chamber of the hydraulic cylinder. In particular, the unloading circuit also includes an unloading relief valve 73 and an unloading ball valve 74. Both the unloading relief valve 73 and the unloading ball valve 74 are connected in parallel with the throttle valve 71 and the solenoid ball valve 72 connected in series. The unloading relief valve 73 is used for overpressure protection of the rod chamber of the hydraulic cylinder, and the unloading ball valve 74 is used for manual pressure relief of the rod chamber of the hydraulic cylinder.

[0028] Both the first pressure oil circuit 51 and the second pressure oil circuit 52 are equipped with pressure oil circuit ball valves 44, which are used for pressure adjustment, pressure testing and hydraulic system fault handling in the hydraulic station. The pressure oil circuit ball valve 44 on the second pressure oil circuit 52 is located after the unloading circuit.

[0029] Hydraulic pump 2 is driven by electric motor 21. The outlet end of hydraulic pump 2 is equipped with high pressure filter 22, outlet relief valve 23, outlet check valve 24, and outlet pressure gauge 25. The oil inlet of high pressure filter 22 is connected to the oil outlet of hydraulic pump 2 for filtering hydraulic oil at the outlet of hydraulic pump. The outlet relief valve 23 is installed in parallel on the oil outlet of high pressure filter 22 for overpressure protection of hydraulic oil at the outlet of hydraulic pump 2. The outlet check valve 24 is used to prevent backflow of hydraulic oil at the outlet of hydraulic pump 2. The outlet pressure gauge 25 is used to display the pressure at the outlet of hydraulic pump 2.

[0030] The accumulator valve platform includes a rodless chamber circuit 61, a rod chamber circuit 62, and an accumulator 63. The rodless chamber circuit 61 connects the first pressure oil circuit 51 and the rodless chambers of multiple hydraulic cylinders 3. The rod chamber circuit 62 connects the second pressure oil circuit 52 and the rod chambers of multiple hydraulic cylinders 3. The accumulator 63 is located on the rod chamber circuit 62 and is used for pressure holding and overpressure protection of the rod chambers of the hydraulic cylinders.

[0031] The accumulator valve platform includes a pressure sensor 64 installed on the rod chamber circuit 62, which is used to monitor the oil pressure in the rod chamber of the hydraulic cylinder in real time. When the oil pressure changes, it can pressurize or depressurize the circuit according to a preset program, or shut down the hydraulic system or the sand making machine.

[0032] The accumulator valve platform also includes a pressure relief circuit on the rod chamber circuit 62, and a pressure relief ball valve 65 is provided on the pressure relief circuit for manual pressure relief of the rod chamber of the hydraulic cylinder.

[0033] An isolation ball valve 66 is provided at the connection between the accumulator 63 and the rod-shaped cavity circuit 62 to isolate the accumulator 63 when it is damaged or in standby mode.

[0034] Specifically, the number of accumulators 63 in the accumulator valve platform is set according to specific requirements. This embodiment takes setting two accumulators 63 as an example for explanation, and based on two accumulators 63, two implementation schemes are given as follows.

[0035] Option 1: Two accumulators 63, one in use and one on standby, are used to maintain pressure in the rod chamber of the hydraulic cylinder. The charging pressure is 65%~75% of the working pressure. The isolation ball valve 66 under the working accumulator 63 is open, and the isolation ball valve 66 under the standby accumulator 63 is closed. When the working accumulator 63 is damaged, the isolation ball valve 66 under the working accumulator 63 can be closed and the isolation ball valve 66 under the standby accumulator 63 can be opened to switch between the two.

[0036] Option 2: Both accumulators 63 operate simultaneously. One is used to maintain pressure in the rod chamber of the hydraulic cylinder, with an air pressure of 65% to 75% of the working pressure. The other is used to absorb hydraulic shock in the rod chamber of the hydraulic cylinder, with an air pressure of 115% to 125% of the working pressure. The isolation ball valves 66 below both accumulators 63 are open.

[0037] In Scheme 1 and Scheme 2, depending on the specifications and working conditions of the sand making machine, the accumulator 63 can be designed as two of the same volume or two of different volumes, so that the hydraulic system has good versatility.

[0038] The oil tank 1 is provided with an oil suction side 11 and an oil return side 12. The oil return side 12 is provided with an oil return filter 13, which is used to filter the hydraulic oil returning to the oil tank 1 to ensure the cleanliness of the oil return.

[0039] A circulating filter cooling circuit is also provided between the oil suction side 11 and the oil return side 12. The circulating filter cooling circuit includes a circulating pump 14, a circulating filter 15, and an air cooler 16. The circulating pump 14 draws hydraulic oil from the oil return side 12 and pumps it to the oil suction side 11. The circulating filter 15 filters the hydraulic oil drawn in by the circulating pump 14, and the air cooler 16 cools the hydraulic oil that has passed through the circulating filter 15. The circulating pump 14 draws hydraulic oil from the oil return side 12, filters it first through the circulating filter 15, and then cools it through the air cooler 16 before returning it to the oil suction side 11, thus achieving circulating cooling and filtration of the hydraulic oil.

[0040] A method for adjusting the start-up of a sand making machine, based on the aforementioned hydraulic system, includes the following steps.

[0041] S1. The sand making machine starts working. The hydraulic pump 2 is started, and the solenoid directional valve 41 is switched so that the pressurized oil enters the rod chamber of the hydraulic cylinder through the second pressure oil circuit 52 and the rod chamber circuit 62. After the hydraulic cylinder rod chamber and accumulator 63 are pressurized to the preset target, the hydraulic pump 2 is turned off, the solenoid directional valve 41 is de-energized and returns to the neutral position, and the sand making machine is started to carry out production operations.

[0042] S2. When the sand making machine is working normally, the hydraulic pump 2 and the solenoid valve are de-energized. Under the action of the hydraulic cylinder 3, the moving roller 81 of the sand making machine maintains the preset pressure and roller gap with the fixed roller 82. The accumulator 63 is used for pressure holding and overpressure protection of the rod chamber of the hydraulic cylinder.

[0043] S3. Pressure adjustment during sand making machine operation: When the pressure of the rod chamber of the hydraulic cylinder drops below the minimum preset value during sand making machine operation, the hydraulic cylinder rod chamber pressurization action is executed. The hydraulic pump 2 is started, and the solenoid directional valve 41 is switched so that the pressurized oil enters the rod chamber of the hydraulic cylinder through the second pressure oil circuit 52 and the rod chamber circuit 62. After the hydraulic cylinder rod chamber and accumulator 63 are pressurized to the preset target, the hydraulic pump 2 is turned off, and the solenoid directional valve 41 is de-energized and returns to the neutral position. When the pressure in the rod chamber of the hydraulic cylinder is higher than the maximum preset value during the operation of the sand making machine, the hydraulic cylinder rod chamber pressure relief action is executed, and the solenoid ball valve 72 is activated. After the pressure in the rod chamber of the hydraulic cylinder drops to the preset range, the solenoid ball valve 72 is closed.

[0044] S4. The sand making machine stops normally. After crushing stops, the hydraulic cylinder rod chamber is depressurized. The solenoid ball valve 72 is started. After the pressure in the hydraulic cylinder rod chamber drops below 1MPa, the solenoid ball valve 72 is closed, and the sand making machine stops.

[0045] S5. When the moving roller retracts and the sand making machine needs maintenance, the hydraulic cylinder rodless chamber is pressurized. The hydraulic pump 2 is started, and the solenoid directional valve 41 is switched so that the pressurized oil enters the rodless chamber of the hydraulic cylinder through the first pressure oil circuit 51 and the rodless chamber circuit 61. At the same time, the hydraulic cylinder rod chamber and the accumulator 63 are depressurized. After the moving roller 81 retracts to the preset position, the hydraulic pump 2 is turned off, and the solenoid directional valve 41 is de-energized and returns to the neutral position.

[0046] In practice, the sand making machine starts working as follows: the rod chamber of the hydraulic cylinder is pressurized, the motor 21 and the solenoid directional valve 41 are energized, the hydraulic pump 2 starts and the solenoid directional valve switches to the left position. When the accumulator 63 and the rod chamber of the hydraulic cylinder are pressurized to the set value, the motor 21 and the solenoid directional valve 41 are de-energized, the hydraulic pump 2 stops and the solenoid directional valve switches back to the neutral position, and the sand making machine starts working.

[0047] Normal operation of the sand making machine: During normal continuous operation of the sand making machine, the motor 21 and all solenoid valves are de-energized. Under the pulling force of the hydraulic cylinder 3, the moving roller 81 of the sand making machine maintains a certain pressure and roller gap with the fixed roller 82 to squeeze the material between them. The accumulator 63 is used for pressure holding and overpressure protection of the rod chamber of the hydraulic cylinder.

[0048] Pressure adjustment during sand making machine operation: When the pressure in the rod chamber of the hydraulic cylinder is lower than the minimum value during operation, the rod chamber of the hydraulic cylinder is pressurized. Motor 21 and solenoid directional valve 41 are energized, hydraulic pump 2 starts, and the solenoid directional valve switches to the left position. When the accumulator 63 and the rod chamber of the hydraulic cylinder are pressurized to the set value, motor 21 and solenoid directional valve 41 are de-energized, hydraulic pump 2 stops, and the solenoid directional valve switches back to the neutral position. When the pressure in the rod chamber of the hydraulic cylinder is higher than the maximum value during operation, the rod chamber of the hydraulic cylinder is depressurized. Solenoid ball valve 72 is energized and opened until the pressure returns to the set value, at which point solenoid ball valve 72 is de-energized and closed.

[0049] Sand making machine shutdown: When the sand making machine is shut down normally, the hydraulic cylinder rod chamber is depressurized and the solenoid ball valve 72 is energized and opened until the pressure is reduced to below 1MPa. Then the solenoid ball valve 72 is de-energized and closed, and the sand making machine stops.

[0050] Moving roller retraction: When the sand making machine needs maintenance, the rodless chamber of the hydraulic cylinder is pressurized. The motor 21 and the solenoid directional valve 41 are energized, the hydraulic pump 2 starts and the solenoid directional valve switches to the right position, the rodless chamber of the hydraulic cylinder is pressurized, and at the same time the accumulator 63 and the rod chamber of the hydraulic cylinder are depressurized. When the moving roller 81 retracts to meet the site requirements, the motor 21 and the solenoid directional valve 41 are de-energized, the hydraulic pump 2 stops and the solenoid directional valve switches back to the neutral position, and the moving roller 81 retracts to the position.

[0051] Hydraulic system circulation filtration and cooling: During normal operation of the sand making machine, the hydraulic system circulation filtration and cooling action can be performed. The circulation pump 14 and the air cooler 16 are powered on and started. The circulation pump 14 draws hydraulic oil from the return oil side 12 of the oil tank 1. The hydraulic oil at the outlet of the circulation pump 14 first passes through the circulation filter 15, and then flows back to the suction oil side 11 of the oil tank 1 through the air cooler 16, ensuring the cleanliness and temperature of the hydraulic oil.

[0052] It should be noted that the parts not described in detail in this solution are all prior art. The above embodiments are only used to illustrate the present invention, but the present invention is not limited to the above embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A hydraulic system for a sand making machine, characterized in that: It includes an oil tank (1), a hydraulic pump (2), a hydraulic control valve group, an accumulator valve platform, and a hydraulic cylinder (3). The hydraulic control valve assembly includes a solenoid directional valve (41). Switching the solenoid directional valve (41) can control the pressure oil output by the hydraulic pump (2) to enter the first pressure oil circuit (51) or the second pressure oil circuit (52) to control the extension or retraction of the piston rod (31) of the hydraulic cylinder (3). The second pressure oil circuit (52) is also equipped with a hydraulically controlled check valve (42) for maintaining pressure after the rod chamber of the hydraulic cylinder is filled with fluid. The accumulator valve platform includes a rodless chamber circuit (61), a rod chamber circuit (62), and an accumulator (63). The rodless chamber circuit (61) connects the first pressure oil circuit (51) and the rodless chambers of multiple hydraulic cylinders (3). The rod chamber circuit (62) connects the second pressure oil circuit (52) and the rod chambers of multiple hydraulic cylinders (3). The accumulator (63) is located on the rod chamber circuit (62) and is used for pressure holding and overpressure protection of the rod chambers of the hydraulic cylinders. The oil tank (1) is provided with an oil suction side (11) and an oil return side (12). The oil return side (12) is provided with an oil return filter (13) for filtering the hydraulic oil returning to the oil tank (1). A circulating filter cooling circuit is also provided between the oil suction side (11) and the oil return side (12). A circulating pump (14), a circulating filter (15) and an air cooler (16) are provided in sequence on the circulating filter cooling circuit. The circulating pump (14) is used to draw hydraulic oil from the oil return side (12) and pump it to the oil suction side (11). The circulating filter (15) is used to filter the hydraulic oil drawn in by the circulating pump (14). The air cooler (16) is used to cool the hydraulic oil that has passed through the circulating filter (15).

2. The hydraulic system for a sand making machine as described in claim 1, characterized in that: The solenoid directional valve (41) is a three-position four-way solenoid directional valve (41), and the middle position function is H type.

3. The hydraulic system for a sand making machine as described in claim 1, characterized in that: Both the first pressure oil circuit (51) and the second pressure oil circuit (52) are equipped with a one-way throttle valve (43) for adjusting the oil outlet flow of the first pressure oil circuit (51) or the second pressure oil circuit (52) to prevent the hydraulic cylinder (3) from moving too fast and causing multiple hydraulic cylinders (3) to move asynchronously. The one-way throttle valve (43) on the second pressure oil circuit (52) is located after the hydraulic control one-way valve (42).

4. The hydraulic system for a sand making machine as described in claim 3, characterized in that: The second pressure oil circuit (52) is provided with an unloading circuit after the one-way throttle valve (43) for overpressure protection of the rod chamber of the hydraulic cylinder. The unloading circuit includes a throttle valve (71) and a solenoid ball valve (72) connected in series. The throttle valve (71) is used to limit the pressure relief speed of the rod chamber of the hydraulic cylinder.

5. The hydraulic system for a sand making machine as described in claim 4, characterized in that: The unloading circuit also includes an unloading relief valve (73) and an unloading ball valve (74). The unloading relief valve (73) and the unloading ball valve (74) are both connected in parallel with the series-connected throttle valve (71) and solenoid ball valve (72). The unloading relief valve (73) is used for overpressure protection of the rod chamber of the hydraulic cylinder, and the unloading ball valve (74) is used for manual pressure relief of the rod chamber of the hydraulic cylinder.

6. The hydraulic system for a sand making machine as described in claim 5, characterized in that: The first pressure oil circuit (51) or the second pressure oil circuit (52) is equipped with a pressure oil circuit ball valve (44) for pressure adjustment, pressure testing and hydraulic system fault handling in the hydraulic station. The pressure oil circuit ball valve (44) on the second pressure oil circuit (52) is located after the unloading circuit.

7. The hydraulic system for a sand making machine as described in claim 1, characterized in that: The accumulator valve platform includes a pressure sensor (64) installed on the rod chamber circuit (62) for real-time monitoring of the oil pressure in the rod chamber of the hydraulic cylinder. When the oil pressure changes, it can pressurize or depressurize the circuit according to a preset program, or shut down the hydraulic system or the sand making machine.

8. The hydraulic system for a sand making machine as described in claim 1, characterized in that: The accumulator valve platform includes a pressure relief circuit on the rod chamber circuit (62), and a pressure relief ball valve (65) is provided on the pressure relief circuit for manual pressure relief of the rod chamber of the hydraulic cylinder.

9. The hydraulic system for a sand making machine as described in claim 1, characterized in that: An isolation ball valve (66) is provided at the connection between the accumulator (63) and the rod chamber circuit (62) to isolate the accumulator (63) in case of damage or standby.

10. A method for adjusting the start-up of a sand making machine, based on the hydraulic system as described in claim 1, characterized in that: Includes the following steps, S1. The sand making machine starts working. The hydraulic pump (2) is started, and the solenoid directional valve (41) is switched so that the pressure oil enters the rod chamber of the hydraulic cylinder through the second pressure oil circuit (52) and the rod chamber circuit (62). After the hydraulic cylinder rod chamber and the accumulator (63) are pressurized to the preset target, the hydraulic pump (2) is turned off, the solenoid directional valve (41) is de-energized and returns to the neutral position, and the sand making machine is started to carry out production operations. S2. When the sand making machine is working normally, the hydraulic pump (2) and the solenoid valve are de-energized. Under the action of the hydraulic cylinder (3), the moving roller (81) of the sand making machine maintains the preset pressure and roller gap with the fixed roller (82). The accumulator (63) is used for pressure holding and overpressure protection of the rod chamber of the hydraulic cylinder. S3. Pressure adjustment during sand making machine operation: When the pressure in the rod chamber of the hydraulic cylinder drops below the minimum preset value during sand making machine operation, the hydraulic cylinder rod chamber pressurization action is executed. The hydraulic pump (2) is started, and the solenoid directional valve (41) is switched so that the pressurized oil enters the rod chamber of the hydraulic cylinder through the second pressure oil circuit (52) and the rod chamber circuit (62). After the hydraulic cylinder rod chamber and accumulator (63) are pressurized to the preset target, the hydraulic pump (2) is turned off, and the solenoid directional valve (41) is de-energized and returns to the neutral position. When the pressure in the rod chamber of the hydraulic cylinder is higher than the maximum preset value during the operation of the sand making machine, the hydraulic cylinder rod chamber pressure relief action is performed, and the solenoid ball valve (72) is started. After the pressure in the rod chamber of the hydraulic cylinder drops to the preset range, the solenoid ball valve (72) is closed. S4. The sand making machine stops normally. After the crushing stops, the hydraulic cylinder rod chamber is depressurized and the solenoid ball valve (72) is started. After the pressure in the hydraulic cylinder rod chamber drops below 1MPa, the solenoid ball valve (72) is closed and the sand making machine stops. S5. When the moving roller retracts and the sand making machine needs maintenance, the hydraulic cylinder rodless chamber pressurization action is performed, the hydraulic pump (2) is started, and the solenoid directional valve (41) is switched so that the pressurized oil enters the hydraulic cylinder rodless chamber through the first pressure oil circuit (51) and the rodless chamber circuit (61). At the same time, the hydraulic cylinder rod chamber and the accumulator (63) are depressurized. After the moving roller (81) retracts to the preset position, the hydraulic pump (2) is turned off, and the solenoid directional valve (41) is de-energized and returns to the neutral position.

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