Control structure of overload protection device

Abstract

The utility model provides a control structure of an overload protection device. Core components of the control structure comprise an oil chamber body, a booster pump, a pressure relief device, a limit switch and an air pressure device. The booster pump is complex in structure and comprises parts such as a body structure, a piston, a piston sleeve and a silencing structure. The oil chamber body is provided with an oil pressure outlet, the booster pump is located on the rear side, the pressure relief device is located on the front side, and the limit switch is located above. The air pressure device is communicated with an oil pressure outlet in the oil chamber body, and an air pressure valve on the outer side of the air pressure device can control the oil drainage channel and the oil through hole to adjust oil pressure in the device. In addition, the silencing structure of the booster pump is located on the rear side of the body structure, all the pistons, the mandrel, the connector and the reset spring cooperatively operate, and stable operation of the booster pump is guaranteed. According to the device, through mutual cooperation of all the components, effective protection on equipment is achieved, and damage to the equipment due to the overload condition is prevented.

Description

Technical Field

[0001] This utility model relates to a control structure for an overload protection device that can be installed on a punch press. In particular, the device can detect the oil pressure to protect the mold and the punch press from damage, and can perform pressure relief and calibration at any time during the mold calibration process. Background Technology

[0002] The conventional structure of a punch press mainly uses a hydraulic cylinder to drive the punch of the press to move up and down to press the workpiece. Generally speaking, the pressing action of the punch press is balanced and stabilized by a hydraulic device. Therefore, when there is an overload or insufficient pressure, the limit switch will be activated to urgently control the operation of the machine in order to protect the mold and the punch press machine.

[0003] Conventional limit switch devices must maintain pressure balance with the booster pump and oil chamber body. Therefore, the setting position of the limit switch must be quite precise. Consequently, conventional limit switch installation requires the use of a thickness gauge to adjust the setting screw, making installation cumbersome. Furthermore, conventional overload protection devices, when installed on the oil tank, typically include a filter inside the tank. However, this often allows metal shavings and other contaminants to enter the oil chamber body, thus affecting machine operation.

[0004] Therefore, how to solve the problems and deficiencies of the existing technologies is the research topic that relevant businesses are eager to develop. Utility Model Content

[0005] The main purpose of this invention is to provide a control structure for an overload protection device.

[0006] This utility model provides a control structure for an overload protection device, including an oil chamber body, a booster pump, a pressure relief device, a limit switch, and a pneumatic device. The booster pump includes a body structure, a first piston, a first piston sleeve, a silencing structure, a second piston, a second piston sleeve, a spindle, a connector, and a return spring. The oil chamber body has an oil pressure outlet. The booster pump is located at the rear of the oil chamber body. The pressure relief device is located at the front of the oil chamber body. The limit switch is located above the oil chamber body. The pneumatic device communicates with the oil pressure outlet within the oil chamber body, and an oil drain channel extending from the outside to the oil through-hole is provided near the oil through-hole. The pneumatic device is lockable at the oil passage, and the booster pump is connected to the pneumatic device via its pneumatic hose. The pneumatic device is locked to the oil passage on one side of the oil chamber body. This oil passage communicates with the oil pressure outlet inside the oil chamber body, and an oil drain channel extending from the outside to the oil passage is provided near the oil passage. A pneumatic valve is provided on the outside of the pneumatic device, and an air passage runs through the inside of the pneumatic valve. The pneumatic valve is used to control the air passage communicating with the oil drain channel, and at the same time, it can control the oil passage that is axially arranged and communicates with the oil drain channel. The silencing structure is located on the rear side of the main body structure. The first piston is fitted into the first piston sleeve and located on the top of the main body structure. The second piston is fitted into the second piston sleeve and located on the front side of the main body structure. One end of the spindle passes through the center of the first piston, and the other end of the spindle passes through the connector, which abuts against the return spring. The return spring abuts against the rear side of the oil chamber body.

[0007] In one embodiment of the present invention, the main body structure has an air inlet. After the airflow enters through the air inlet, it pushes the first piston to move downward, thereby pressurizing the internal air to push the second piston to move forward and compress the return spring, thereby applying air pressure to the oil chamber body.

[0008] In one embodiment of this utility model, the pressure relief device is composed of a movable pressure rod, a piston, an adjusting screw, and an inner groove. The inner groove is used to lock the adjusting screw in, and in addition to the adjustment screw being screwed into the inner groove, a hole is also provided in the inner groove for self-adjustment of the pressure to balance the control of the movable pressure rod and the limit switch. By controlling the adjusting screw, the piston is held against the oil drain channel, which serves as a determination to release pressure.

[0009] In one embodiment of this utility model, the piston in the pressure relief device that controls the limiting switch is provided with nano-oil grooves, which can discharge a very small amount of hydraulic oil and control the discharge of oil to 3 to 4 drops per second, thereby releasing pressure.

[0010] In one embodiment of this utility model, when the hydraulic oil pressure exceeds the preset pressure value, the pressure exceeding the preset value will drive the valve to move the piston backward, thereby causing the movable pressure rod to be displaced and driving the switch on the limit switch to perform an action. The action of the switch will cause the contact part to establish contact with the wire, conduct a signal, and thus immediately activate the pressure relief function of the limit switch.

[0011] In one embodiment of this invention, when the oil pressure is insufficient, the pressure inside the pressure relief device will exceed the pressure inside the oil chamber body. This pressure difference causes the movable pressure rod and the piston to work together to push the valve forward. At the same time, the movable pressure rod will also apply pressure to the limit switch, causing it to activate and thus establishing contact between the contact part and the wire, transmitting electrical signals.

[0012] In one embodiment of this utility model, when the hydraulic oil pressure exceeds the set standard but does not reach the threshold for activating the limit switch to release pressure, a small amount of pressure is released using the nano-oil groove structure on the piston.

[0013] In one embodiment of this utility model, when the oil pressure value is maintained within the normal range, gas will enter the device through the air passage, and the air pressure valve will remain closed, which will prevent hydraulic oil from being discharged through the oil passage and the drain passage.

[0014] In one embodiment of this utility model, when the movable pressure rod moves, it pushes the switch to trigger an electrical signal, making the contact part connected with the wire and transmitting it to the punch press control system.

[0015] In summary, the control structure of the overload protection device disclosed in this utility model can bring the following benefits:

[0016] 1. Improved installation convenience. Quick-release filter design: The oil inlet filter is secured with a flexible retaining ring, reducing maintenance and replacement time to 2 minutes and lowering equipment downtime maintenance costs.

[0017] 2. Pressure Control Accuracy and Stability. Nano-oil groove micro-pressure relief: Micro-oil leakage (3-4 drops / second) is achieved through nano-oil grooves on the piston surface, controlling pressure fluctuations within ±3%, effectively eliminating false alarms caused by oil temperature rise (approximately 5% oil pressure fluctuation for every 10°C increase), and improving equipment operational reliability. Pneumatic valve rapid pressure relief: The pneumatic device completes pressure relief within 3 seconds in the event of a power outage. Compared to traditional mechanical pressure relief devices (requiring more than 10 seconds), this significantly shortens the pressure relief waiting time during the die-setting process, improving the die-setting efficiency of the punch press by more than 30%.

[0018] 3. Impurity Filtration and Component Protection. Dual-layer filter structure: The filter effectively intercepts impurity particles ≥50μm, reducing the impurity concentration inside the oil chamber 1 from 500 particles / mL in the traditional structure to below 50 particles / mL, extending the service life of hydraulic components (such as pistons and valves) by more than 2 times.

[0019] 4. Enhanced Adaptability and Safety. Wide-Range Pressure Adjustment: The pressure relief valve's adjusting screw, in conjunction with the graduated ring, allows for precise setting of working pressures from 10 to 20 MPa, making it suitable for punch presses of various tonnages (50 to 200 tons), demonstrating strong versatility. Two-Way Pressure Protection: It simultaneously features overpressure emergency stop and underpressure compensation functions, reducing the mold damage rate caused by abnormal loads on punch presses from 15% in traditional structures to below 3%, significantly improving production safety.

[0020] 5. Energy saving and environmental protection benefits. Micro-drainage oil recovery: The extremely small amount of hydraulic oil discharged through the nano-oil channel is stored in the oil tank (about 0.5L / 8 hours), avoiding the oil waste and environmental pollution caused by direct discharge in traditional structures, and meeting the requirements of industrial energy saving and environmental protection.

[0021] The following detailed description of specific embodiments will make it easier to understand the purpose, technical content, features and effects achieved by this utility model. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall control structure of the overload protection device of this utility model.

[0023] Figure 2 This is another overall schematic diagram of the control structure of the overload protection device of this utility model.

[0024] Figure 3 This is a three-dimensional exploded view of the booster pump of this utility model.

[0025] Figure 4 This is another exploded perspective view of the booster pump of this utility model.

[0026] Figure 5 This is a schematic diagram of the main body structure of the booster pump of this utility model.

[0027] Figure 6 This is a cross-sectional view showing the operation of the booster pump of this utility model.

[0028] Figure 7 This is a cross-sectional view showing another operation of the booster pump of this utility model.

[0029] Figure 8 This is a schematic diagram of the operation of the control structure of the overload protection device of this utility model.

[0030] Figure 9This is another schematic diagram of the control structure of the overload protection device of this utility model.

[0031] Figure reference numerals: 10-Control structure of overload protection device; 1-Oil chamber body; 12-Oil inlet; 121-Filter screen; 13-Oil pressure outlet; 14-Oil drain port; 15-Valve; 151-Channel; 16-Oil drain channel; 17-Oil pressure inlet; 18-Oil through hole; 19-Oil drain channel; 2-Booster pump; 201-Body structure; 201A-Air inlet; 202-First piston; 203-First piston sleeve; 204-Silencer structure; 205-Second piston; 206-... Two-piston sleeve; 207-spindle; 208-connector; 209-return spring; 21-pneumatic pipe; 3-pressure relief device; 31-movable pressure rod; 32-piston; 321-nano oil groove; 322-oil groove; 33-adjusting screw; 34-inner groove; 4-limiting switch; 41-outer housing; 411-locking element; 42-switch; 421, 422-contact parts; 423-wire; 5-pneumatic device; 51-pneumatic valve; 52-air passage; 53-oil through hole; 54-oil drain channel. Detailed Implementation

[0032] The designer of this invention has conducted years of research and development to improve upon the shortcomings of existing products. The following sections will detail how this utility model achieves the most efficient functional requirements through a control structure for an overload protection device. The data mentioned below are for illustrative purposes only; however, actual data may vary depending on specific circumstances and is not limited to the data presented below.

[0033] Please see Figures 1 to 9 As shown, this utility model provides an overload protection device 10, which comprises an oil chamber body 1, a booster pump 2, a pressure relief device 3, a limit switch 4, and a pneumatic device 5. The booster pump 2 and the pressure relief device 3 are respectively located on both sides of the oil chamber body 1, and the limit switch 4 is installed above the oil chamber body 1. The structure, assembly relationship, and actuation mechanism of each component will be described in detail below with reference to the accompanying drawings.

[0034] The oil chamber body 1 has an oil inlet 12, an oil pressure outlet 13, and an oil drain 14 at its lower part. Inside the oil chamber body 1 is an oil chamber with an oil circuit and a valve 15. A filter screen 121 is installed at the oil inlet 12 to prevent iron filings, powder, or other contaminants from directly entering the oil chamber body 1 during oil intake, thus maximizing its operational efficiency. In other words, the filter screen 121 embedded at the oil inlet 12, which can be made of stainless steel with a mesh density of 500μm, filters iron filings, metal powder, and other impurities, preventing them from entering the oil chamber body 1 and causing blockages in the oil circuit or wear on components, thereby ensuring the operational efficiency of the hydraulic system. The oil pressure outlet 13 is located on the side wall of the oil chamber body 1 and connects to the oil passage 18 via an internal oil circuit. The outer end of the oil passage 18 is used to connect to the pneumatic device 5, forming a key connection node for hydraulic and pneumatic control.

[0035] The booster pump 2 is located on one side of the oil chamber body 1. Its function is to fill the channels within the oil chamber body 1 with hydraulic oil from the tank, thereby driving the punch press to perform the stamping action. In other words, the booster pump 2 is installed on the left side of the oil chamber body 1, with its inlet connected to an external oil tank and its outlet connected to the interior of the oil chamber body 1 via an oil passage. The booster pump 2 has a pneumatic pipe 21 on its top, made of high-pressure resistant rubber, used to connect to the pneumatic device 5 and transmit pneumatic signals to control the pressure relief action. When the booster pump 2 operates, it pressurizes the hydraulic oil in the tank and delivers it to the oil chamber body 1, filling the channels and driving the punch press to perform the stamping action.

[0036] In addition, the booster pump includes a main body structure 201, a first piston 202, a first piston sleeve 203, a silencing structure 204, a second piston 205, a second piston sleeve 206, a spindle 207, a connector 208, and a return spring 209. The silencing structure 204 is disposed on the rear side of the main body structure 201. The first piston 202 is fitted into the first piston sleeve 203 and disposed above the main body structure 201. The second piston 205 is fitted into the second piston sleeve 206 and disposed on the front side of the main body structure 201. One end of the spindle 207 passes through the center of the first piston 202, and the other end of the spindle 207 passes through the connector 208, after which the connector 208 abuts against the return spring 209, wherein the return spring 209 abuts against the rear side of the oil chamber body 1. The main body structure 201 has an air inlet 201A. After the airflow enters through the air inlet 201A, it pushes the first piston 202 downward, thereby pressurizing the internal air to push the second piston 205 forward and compress the return spring 209, thereby applying air pressure to the oil chamber body 1.

[0037] The pressure relief device 3 is located on one side of the oil chamber body 1, and it consists of a movable pressure rod 31, a piston 32, an adjusting screw 33, and an inner groove 34. The inner groove 34 of the pressure relief device 3 body allows the adjusting screw 33 to be locked in place. In addition to the engagement of the adjusting screw 33, the inner groove 34 also has a pre-drilled hole for adjusting the pressure to balance the control of the movable pressure rod 31 and the limit switch 4. By controlling the adjusting screw 33, the piston 32 is held against the oil drain channel 16, thus triggering pressure relief. In other words, the inner wall of the inner groove 34 is threaded, and the adjusting screw 33 is screwed into the inner groove 34, with its end abutting against the piston 32. Rotating the adjusting screw 33 changes the initial position of the piston 32, thereby setting the pressure relief trigger pressure value and balancing the control relationship between the movable pressure rod 31 and the limit switch 4. The outer diameter of the piston 32 and the inner diameter of the inner groove 34 are precisely matched to form a hydraulic seal. When the oil pressure exceeds the set value, the piston 32 retracts, driving the movable pressure rod 31 to move and opening the oil drain channel 16, allowing excess hydraulic oil to be discharged from the oil drain port 14.

[0038] The aforementioned limiting switch 4 is mounted on the oil chamber body 1 and can be locked in place by the locking element 411. The housing 41 contains contact parts 421 and 422 and a wire 423. The wire 423 allows the contact parts 421 and 422 to be positioned at their respective ends. The switch 42, located outside the limiting switch 4, is connected to the movable pressure rod 31 of the pressure relief device 3, transmitting a signal to cause the pressure relief device 3 to release pressure. In other words, the outer layer of the wire 423 in the housing 41 can be an oil-resistant insulating layer, and the inner core can be tin-plated copper wire. The switch 42 is located at the front end of the housing 41 and contacts the movable pressure rod 31 of the pressure relief device 3. When the movable pressure rod 31 moves, it pushes the switch 42 to trigger an electrical signal, making the contact parts 421 / 422 connected to the wire 423, transmitting the signal to the punch press control system.

[0039] The pneumatic device 5 is locked at the oil passage hole 18 on the side wall of the oil chamber body 1. Its composition and operation are as follows: The pneumatic valve 51 has an air source interface on its outside and an internal air passage 52 with a diameter of 5mm, which connects to an external pneumatic system. The pneumatic valve 51 has a spring and a valve core inside. Under normal conditions (when the pneumatic system supplies air), the valve core closes the oil drain passage 54 and the axially arranged oil passage hole 53 under the action of air pressure. When it is necessary to temporarily shut down the device, the booster pump 2 is turned off and the air pressure supply is cut off. A negative pressure is formed inside the pneumatic valve 51, and the spring pushes the valve core to open the oil drain passage 54 and the oil passage hole 53. At this time, the hydraulic oil in the oil chamber body 1 is discharged from the drain port 14 through the oil pressure outlet 13 → oil passage hole 18 → oil passage hole 53 → oil drain passage 54, achieving rapid pressure relief.

[0040] During normal stamping operations, the overload protection device 10 monitors pressure changes. When the pressure exceeds 50% of the set pressure, the device's internal automatic adjustment mechanism will start operating. Its purpose is to eliminate the erroneous overload self-explosion phenomenon caused by the rise in oil temperature during the stamping process, and to ensure that the stamping press can obtain a relatively stable stamping pressure when performing stamping work, thereby improving the quality and efficiency of stamping.

[0041] When the press is overloaded, it means that the hydraulic oil pressure in the tank exceeds the preset pressure value. Under normal conditions, valve 15 and piston 32 are in contact with each other to prevent hydraulic oil from flowing between them. However, when the oil pressure increases, hydraulic oil begins to fill the space between valve 15 and piston 32. At this time, this excess hydraulic oil must be discharged through the channel 151 provided on valve 15. Specifically, the pressure exceeding the set value will drive valve 15 to move piston 32 backward, thereby displacing the movable pressure rod 31 and actuating switch 42 on the limit switch 4. The actuation of switch 42 will establish contact between contact part 422 and wire 423, transmitting a signal and immediately activating the pressure relief function of limit switch 4. At the same time, excess hydraulic oil will be discharged through drain channel 16. In addition, the device will send an electrical signal to notify the press to perform an emergency stop and the pneumatic solenoid valve supplied to the control structure 10 of the overload protection device must be closed.

[0042] In the event of insufficient pressure in the overload protection device 10—in other words, when the hydraulic pressure is insufficient—the pressure inside the pressure relief device 3 will exceed the pressure inside the oil chamber body 1. This pressure difference causes the movable pressure rod 31 and the piston 32 to work together, pushing the valve 15 forward. Simultaneously, the movable pressure rod 31 also applies pressure to the switch 42 of the limit switch 4, causing it to actuate and establishing contact between the contact part 421 and the wire 423, transmitting an electrical signal. It is worth noting that in order for the punch press to smoothly eliminate or recover from an overload condition after it occurs, the punch press must resume normal stamping operations. This requires the pneumatic solenoid valve to be energized, and the air-driven hydraulic pump to quickly replenish the normal pressure required by the hydraulic cylinder, ensuring that the punch press can immediately resume normal stamping operations.

[0043] Under normal operating conditions, when the hydraulic oil pressure exceeds the set standard but does not reach the threshold for activating the limit switch 4 to release pressure, the device uses a nano-groove 321 structure on the piston 32 for minor pressure relief. Specifically, a plurality of nano-grooves 321 are machined on the outer surface of the piston 32, with the following geometric dimensions: groove width 50μm, groove depth 30μm. The function of these nano-grooves 321 is to control a very small amount of hydraulic oil (flow rate controlled at 3-4 drops / second) to leak along the flow channels of the nano-grooves 321 when the hydraulic system pressure slightly exceeds the standard (i.e., the pressure value is between the set standard and the activation pressure of the limit switch 4) when it exceeds the standard. This allows the oil to collect in the oil groove 322 defined by the piston 32 and the movable pressure rod 31. Through this minor pressure relief mechanism, excess pressure accumulated in the system can be effectively released, thereby suppressing pressure fluctuations, ensuring the stability of system operation, and preventing unexpected actions.

[0044] The booster pump 2 is connected to the pneumatic device 5 through its pneumatic pipe 21. Gas is introduced through the pneumatic device 5 and passes through its internal air passage 52. The pneumatic device 5 is fixed by locking onto an oil passage 18 provided on one side of the oil chamber body 1. This oil passage 18 is interconnected with the oil pressure outlet 13 inside the oil chamber body 1. In addition, an oil drain channel 19 is provided in the vicinity of the oil passage 18, extending from the outside to the oil passage 18. The function of the oil passage 18 is to allow the pneumatic device 5 to be locked in place, and the other end of the oil passage 18 is connected to the oil pressure inlet 17.

[0045] The pneumatic device 5 is provided with a pneumatic valve 51 on the outside. The pneumatic valve 51 has an air passage 52 inside. The pneumatic valve 51 can control the oil drain passage 54 connected to the oil drain passage 19, and can also control the oil passage hole 53 connected to the oil drain passage 54 and arranged axially.

[0046] When the oil pressure of the overload protection device 10 remains within the normal range, gas enters the device through the air passage 52, and the air pressure valve 51 remains closed, preventing hydraulic oil from being discharged through the oil passage 53 and the drain passage 54. However, when it is necessary to temporarily stop the device's operation, shutting off the booster pump 2 will cause the gas pressure inside the device to decrease, thus creating a negative pressure. In this case, the air pressure valve 51 will no longer remain closed, meaning it will no longer prevent hydraulic oil from flowing through the oil passage 53 to the drain passage 54. Through this process, the hydraulic oil is finally discharged, achieving the purpose of pressure relief.

[0047] In summary, the control structure of the overload protection device disclosed in this utility model can bring the following benefits:

[0048] 1. Improved installation convenience. Quick-release filter design: The filter 121 at the oil inlet 12 can be fixed with a flexible retaining ring, reducing maintenance and replacement time to 2 minutes and lowering equipment downtime maintenance costs.

[0049] 2. Pressure Control Accuracy and Stability. Nano-oil groove micro-pressure relief: Through the nano-oil grooves 321 on the surface of piston 32, micro-oil leakage (3-4 drops / second) is achieved, controlling pressure fluctuations within ±3%, effectively eliminating false alarms caused by oil temperature rise (approximately 5% oil pressure fluctuation for every 10℃ increase), and improving equipment operational reliability. Pneumatic valve rapid pressure relief: The pneumatic device 5 completes pressure relief within 3 seconds in the power-off state. Compared to traditional mechanical pressure relief devices (requiring more than 10 seconds), this significantly shortens the pressure relief waiting time during the die-setting process, improving the die-setting efficiency of the punch press by more than 30%.

[0050] 3. Impurity filtration and component protection. Dual-layer filter structure: Filter 121 effectively intercepts impurity particles ≥50μm, reducing the impurity concentration inside the oil chamber body 1 from 500 particles / mL in the traditional structure to below 50 particles / mL, extending the service life of hydraulic components (such as piston 32 and valve 15) by more than 2 times.

[0051] 4. Enhanced Adaptability and Safety. Wide-Range Pressure Adjustment: The adjusting screw 33 of the pressure relief device 3, in conjunction with the graduated ring, allows for precise setting of working pressure from 10 to 20 MPa, making it suitable for punch presses of different tonnages (50 to 200 tons), demonstrating strong versatility. Two-Way Pressure Protection: It simultaneously features overpressure emergency stop and underpressure compensation functions, reducing the mold damage rate caused by abnormal loads on punch presses from 15% in traditional structures to below 3%, significantly improving production safety.

[0052] 5. Energy saving and environmental protection benefits. Micro-discharge oil recovery: The very small amount of hydraulic oil discharged from the nano oil groove 321 (about 0.5L / 8 hours) is stored in the oil tank 322, avoiding the oil waste and environmental pollution caused by direct discharge in traditional structures, and meeting the requirements of industrial energy saving and environmental protection.

[0053] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of implementation of this utility model. Therefore, all equivalent variations or modifications made in accordance with the features and spirit of this utility model should be included within the protection scope of this utility model.

Claims

1. A control structure for an overload protection device, characterized in that, include: An oil chamber body has an oil pressure outlet; A booster pump is located at the rear of the oil chamber body; A pressure relief device is located on the front side of the oil chamber body; A limit switch is disposed above the oil chamber body; and A pneumatic device is connected to the oil pressure outlet inside the oil chamber body, and an oil drain channel extending from the outside to the oil through hole is provided near an oil through hole. The oil passage hole is used to lock the pneumatic device, and the booster pump is connected to the pneumatic device by a pneumatic pipe. The pneumatic device is locked in the oil passage hole on one side of the oil chamber body, and the oil passage hole is connected to the oil pressure outlet in the oil chamber body. The pneumatic device is provided with a pneumatic valve on the outside, and a pneumatic passage is passed through the inside of the pneumatic valve. The pneumatic valve is used to control the pneumatic passage that is connected to the oil drain passage, and at the same time control the oil through hole that is connected to the oil drain passage and is arranged axially. The booster pump includes a main body structure, a first piston, a first piston sleeve, a silencing structure, a second piston, a second piston sleeve, a spindle, a connector, and a return spring. The silencing structure is located on the rear side of the main body structure. The first piston is fitted into the first piston sleeve and located above the main body structure. The second piston is fitted into the second piston sleeve and located on the front side of the main body structure. One end of the spindle passes through the center of the first piston, and the other end of the spindle passes through the connector, which abuts against the return spring. The return spring abuts against the rear side of the oil chamber body.

2. The control structure of the overload protection device as described in claim 1, characterized in that: The main body structure has an air inlet. After the airflow enters through the air inlet, it can push the first piston to move downward, thereby pressurizing the internal air to push the second piston to move forward and compress the return spring, thereby applying air pressure to the oil chamber body.

3. The control structure of the overload protection device as described in claim 1, characterized in that: The pressure relief device consists of a movable pressure rod, a piston, an adjusting screw, and an inner groove. The inner groove is used to lock the adjusting screw in place. In addition to the adjusting screw being screwed into the inner groove, there is also a hole in the inner groove for adjusting the pressure to balance the control of the movable pressure rod and the limit switch. By controlling the adjusting screw, the piston is held in place by the oil drain passage, which determines whether to release pressure.

4. The control structure of the overload protection device as described in claim 3, characterized in that: The piston inside the pressure relief device can control the limit switch. The piston is equipped with nano-oil grooves, which can discharge hydraulic oil and control the discharge of 3 to 4 drops of oil per second to release pressure.

5. The control structure of the overload protection device as described in claim 3, characterized in that: When the hydraulic oil pressure exceeds the preset pressure value, the pressure exceeding the set value will drive the valve to move the piston backward, which will cause the movable pressure rod to move and drive the switch on the limit switch to perform an action. The action of the switch will make the contact part make contact with the wire, conduct a signal, and thus immediately activate the pressure relief function of the limit switch.

6. The control structure of the overload protection device as described in claim 3, characterized in that: When the oil pressure is insufficient, the pressure inside the pressure relief device will exceed the pressure inside the oil chamber. This pressure difference will cause the movable rod and the piston to work together to push the valve forward. At the same time, the movable rod will also apply pressure to the limit switch, causing it to activate and thus establish contact between the contact part and the wire, transmitting electrical signals.

7. The control structure of the overload protection device as described in claim 1, characterized in that: When the hydraulic oil pressure exceeds the set standard but does not reach the threshold for activating the limit switch to release pressure, a small amount of pressure is released using the nano-oil groove structure on the piston.

8. The control structure of the overload protection device as described in claim 1, characterized in that: When the oil pressure value is maintained within the normal range, gas will enter the device through the air passage, and the air pressure valve will remain closed. Its function is to prevent hydraulic oil from being discharged through the oil passage and the drain passage.

9. The control structure of the overload protection device as described in claim 3, characterized in that: When the movable pressure rod moves, it pushes the switch to trigger an electrical signal, making the contact part connected to the wire and transmitting the signal to the punch press control system.

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