A press feed blowout prevention control device and blowout prevention control method

Abstract

The present invention discloses a press feed blowout prevention control device and blowout prevention control method. A feed pressure sensor, a small oil cylinder pressure sensor, and a large oil cylinder pressure sensor are respectively connected to the PLC input end; the PLC output end is connected to a proportional relief valve arranged on the small oil cylinder oil inlet pipeline, and the small oil cylinder pressure is controlled by controlling the opening of the proportional relief valve; the PLC output end is connected to a variable frequency motor driving a feed pump; the feed speed is controlled by controlling the speed of the variable frequency motor driving the feed pump; an A value, i.e., the maximum value of ΔP×S1, is set in the PLC control program, and during the material feeding process, real-time data of P1, P2, and P3 are collected, and the value of ΔP×S1, i.e., the B value, is continuously calculated. Once the B value exceeds the A value, the feed is stopped for pressing; thus, the feed flow rate and the small oil cylinder pressure are automatically adjusted by feedback of the pressure value, and the operation of the equipment is monitored. This method can monitor and adjust the overall equipment from the source to prevent blowout, and solve the problem of feed spray.

Description

Technical Field

[0001] The invention belongs to the technical field of sludge filter pressing and dehydration, and relates to a press feed blowout prevention control device and a blowout prevention control method. Background Art

[0002] The plate-and-frame hydraulic press (hereinafter referred to as the press) is a type of filter press machinery widely used in sludge dewatering. It generally comprises a press body, a feed system, a hydraulic system, and a PLC control system. The press body comprises several filter plates arranged in sequence. Each filter plate comprises a plate frame and a pressure plate (thrust plate), which are covered with filter cloth. Several small cylinders (plungers) are positioned around the plate frame and the pressure plate. The cylinder bodies of the small cylinders are located within the plate frame, and the tops of the piston rods of the small cylinders press against the pressure plate. The rear outer surface of the plate frame of the last filter plate in the press body press against the front outer surface of the thrust plate, while the top of the piston rod of the large cylinder press against the rear outer surface of the thrust plate. The feed system comprises a feed pump and a feed port. The feed port is located in the center of the front filter plate in the press body. The hydraulic system supplies oil to the small and large cylinders. The PLC control system controls the feeding and pressing processes.

[0003] During the feeding process of a plate-and-frame oil cylinder press, the balance between the plate-and-frame feed pressure P1, the small oil cylinder pressure P2, and the large oil cylinder pressure P3 is often not properly controlled, resulting in a decrease in the sealing force of the plate-and-frame, causing leakage and spraying of material between the plate-and-frame and the pressure plate, a phenomenon known as press spray. Press spray is a common problem that not only affects the circulation of the press system and makes it impossible to operate normally, but in severe cases, it can directly damage the filter cloth and filter plates, even causing personal injury and increasing operating costs for the company.

[0004] Existing press equipment usually has the following practices for preventing blowout:

[0005] 1. In the press industry, the plate frame seal usually adopts the method of adding sealing strips or increasing the locking force to prevent the material from spraying during the feeding of the equipment, so as to maintain the normal operation of the equipment. However, due to the aging of the sealing strip, the sealing force will continue to decrease as the sealing strip ages, so it is impossible to achieve a completely reliable seal.

[0006] 2. Add a protective cover on the outside of the equipment. Adding a protective cover can only reduce the impact area after spraying, which is a temporary solution.

[0007] Therefore, it is necessary to study how to start from the feeding operation principle of the press, explore the reasons for the equipment spraying, and solve the problem of press spraying by adding an anti-spraying monitoring program. Summary of the Invention

[0008] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a press feed blowout prevention control device and a blowout prevention control method that solve the press blowout problem by adding a blowout prevention monitoring program.

[0009] The purpose of the present invention is achieved through the following technical solutions:

[0010] The present invention discloses a feed blowout prevention control device for an squeezer, which comprises: a squeezer body, a feed system, a hydraulic system, and a PLC control system; the squeezer body comprises a plurality of filter plate frames arranged in sequence; each filter plate frame comprises a plate frame and a pressure plate, the plate frame is covered with filter cloth, a plurality of small oil cylinders are arranged around the plate frame and the pressure plate, the cylinder bodies of the small oil cylinders are arranged in the plate frame, and the top ends of the piston rods of the small oil cylinders press against the pressure plate; the rear outer surface of the plate frame of the last filter plate frame of the squeezer body presses against the front outer surface of the push plate; the top end of the piston rod of the large oil cylinder presses against the rear outer surface of the push plate; the feed system comprises a feed pump and a feed port; the feed port is provided at the center of the frontmost filter plate frame of the squeezer body; the feed pump is connected to the feed port; the hydraulic system is used for supplying oil to the small oil cylinder and the large oil cylinder; the relief valve on the oil inlet pipe of the small oil cylinder in the hydraulic system is a proportional relief valve;

[0011] The PLC control system includes a PLC controller; a feed pressure sensor is provided at the feed port of the press or the outlet of the feed pump; a small oil cylinder pressure sensor is provided at the oil inlet of the small oil cylinder; a large oil cylinder pressure sensor is provided at the oil inlet of the large oil cylinder; the feed pressure sensor, the small oil cylinder pressure sensor, and the large oil cylinder pressure sensor are respectively connected to the input end of the PLC controller; the output end of the PLC controller is connected to the proportional relief valve provided on the oil inlet pipeline of the small oil cylinder, and the small oil cylinder pressure can be controlled by controlling the opening of the proportional relief valve; the output end of the PLC controller is connected to the motor driving the feed pump, or connected to the proportional valve of the hydraulic drive device of the feed pump; the feed speed can be controlled by controlling the speed of the motor driving the feed pump, or controlling the opening of the proportional valve of the hydraulic drive device of the feed pump.

[0012] Furthermore, the feed pump is driven by a variable frequency motor, and the output end of the PLC controller is connected to the variable frequency motor driving the feed pump; by controlling the working frequency of the variable frequency motor driving the feed pump, the speed of the feed pump can be controlled (and the outlet flow of the feed pump can be controlled at the same time), thereby controlling the feed speed.

[0013] Furthermore, the feed pump is hydraulically driven, and the hydraulic drive device of the feed pump is controlled by a hydraulic proportional valve or proportional relief valve (i.e., the flow rate of the hydraulic oil driving the feed pump is controlled by the hydraulic proportional valve or proportional relief valve). The output end of the PLC controller is connected to the hydraulic proportional valve or proportional relief valve of the hydraulic drive device of the feed pump; by controlling the opening of the hydraulic proportional valve or proportional relief valve of the hydraulic drive device of the feed pump, the speed of the feed pump (and the flow rate at the feed pump outlet can be controlled, thereby controlling the feed speed. The speed of the feed pump can be the rotational speed of the feed pump (screw pump) or the forward / reverse speed of the plunger of the feed pump (plunger pump).

[0014] Furthermore, the diameter d of the feed port (i.e., the central feed hole) of the press is designed to be increased by 55-65%, from the original 120 mm ± 10 mm to an improved design of 200 mm ± 20 mm.

[0015] Furthermore, the length l of the central feed hole of the press is designed to be reduced by 10-15% (from the original 5600 mm ± 100 mm to 5000 ± 100 mm), which can be achieved by reducing the number of press plates and frames.

[0016] The present invention uses the above-mentioned press feed blowout prevention control device to implement a press feed blowout prevention control method as follows: add a blowout prevention monitoring program in the PLC control program, that is, set an A value in the PLC control program, that is, the maximum value of ΔP×S1, where ΔP is the resistance loss along the way, S1 is the filtration area, that is, the plate frame area minus the sealing area S4; when the press is actually running, during the material feeding process, the feed pressure sensor, the small cylinder pressure sensor, and the large cylinder pressure sensor are used to collect the feed pressure. The real-time pressure values ​​of P1, small cylinder pressure P2, and large cylinder pressure P3 are continuously calculated on the value of ΔP×S1, i.e., the B value, through the operator in the PLC controller. Once the actual working value of ΔP×S1, i.e., the B value, exceeds the set value A, the feeding is stopped and the pressing is performed. Thus, the feed pressure, small cylinder pressure, and feed flow rate are automatically adjusted through the pressure values ​​of P1, P2, and P3 fed back by the feed pressure sensor, small cylinder pressure sensor, and large cylinder pressure sensor. This is used to monitor the operation of the equipment and prevent spraying.

[0017] Furthermore, a value A is set in the PLC control program, which is a maximum limit value of ΔP×S1; and a calculation formula for the real-time value B of ΔP×S1 is programmed into the PLC control program: B=P1×S1+P2×S2-P3×S3; wherein, S1 is the filter area, S2 is the sum of the areas of all small oil cylinders, and S3 is the area of ​​the large oil cylinder; in the process of material feeding, the PLC controller continuously collects the values ​​of the feed pressure sensor, the small oil cylinder pressure sensor, and the large oil cylinder pressure sensor, which are the values ​​of the feed pressure P1, the small oil cylinder pressure P2, and the large oil cylinder pressure P3 respectively. Then, the operator in the PLC controller performs continuous calculations according to the B value calculation formula: B=P1×S1+P2×S2-P3×S3 to obtain the B value, and the calculated B The real-time value of the B value, i.e., ΔP×S1, is compared with the set A value, i.e., the maximum limit value of ΔP×S1; if the B value is close to the A value, the PLC controller controls the operating frequency of the motor driving the feed pump or controls the opening of the proportional valve of the hydraulic drive device of the feed pump to reduce the speed of the feed pump, thereby reducing the feed speed v; at the same time, the PLC controller controls the opening of the proportional relief valve on the oil inlet pipe of the small cylinder to increase the small cylinder pressure P2 value; when the feed speed v is reduced to the minimum value (this minimum value is determined by the characteristics of the feed pump) and the small cylinder pressure P2 value increases to the maximum value, the B value still rises; when the B value ≥ the A value, the PLC controller controls the feed pump to stop running, the press ends feeding, and enters the pressing program.

[0018] Beneficial effects of the present invention:

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. This invention, through analysis of hydraulic fluid dynamics, adds a blowout prevention monitoring program to the PLC control program. By feeding back pressure values, it automatically adjusts feed pressure, flow rate, and small cylinder pressure. This enables blowout prevention monitoring and adjustment of the entire equipment at the source, significantly reducing the losses caused by blowout to the enterprise and improving equipment safety.

[0021] 2. The control method of the present invention has been successfully tested in the field operation of multiple projects. The original equipment often had material spraying during the feeding process. After adopting this monitoring method, the problem of material spraying during feeding was solved.

[0022] 3. The use of this control method in the press industry can accurately calculate the sealing force required for the plate and frame, greatly reducing the risk of damage to the plate and frame due to the inability to accurately calculate the sealing force of the plate and frame during the debugging stage.

[0023] 4. It can be applied to the blowout prevention of elastic presses, box-type plate and frame machines, and diaphragm machines. This control method is a more reasonable control logic. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the press and the force analysis of the plate frame in the present invention;

[0025] Figure 2 Schematic diagram of the force-bearing surface (direction A) of the press plate frame 1 in the present invention;

[0026] Figure 3 This is a schematic structural diagram of the press feed blowout prevention control device of the present invention (the feed pump is driven by a variable frequency motor);

[0027] Figure 4 It is a structural schematic diagram of the press feed blowout prevention control device of the present invention (the feed pump is driven by hydraulic pressure).

[0028] Figure: 1, plate frame 2, small oil cylinder 3, large oil cylinder 4, feed port (center feed hole) 5, pressure plate 6, cake 7, feed pressure sensor 8, small oil cylinder pressure sensor 9, large oil cylinder pressure sensor 10, proportional relief valve 11, push plate 12, feed pump 13, frequency conversion motor 14, hydraulic proportional valve 15, proportional relief valve S1, filtration area (i.e., cake area) S2, sum of all small oil cylinder areas S3, large oil cylinder area S4, sealing area P1, feed pressure (i.e., cake pressure) P2, small oil cylinder pressure P3, large oil cylinder pressure F, plate frame sealing force DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Example

[0031] like Figure 1 、 Figure 2 and Figure 3 As shown, the present invention is a press feed blowout prevention control device, which includes: a press body, a feed system, a hydraulic system, and a PLC control system; the press body includes a plurality of filter plate frames arranged in sequence; each filter plate frame includes a plate frame 1 and a pressure plate 5 (thrust plate), the plate frame 1 is covered with filter cloth, and a plurality of small oil cylinders 2 (plunger cylinders) are arranged around the plate frame 1 and the pressure plate 5, the cylinder body of the small oil cylinder 2 is arranged in the plate frame 1, and the top of the piston rod of the small oil cylinder 2 presses against the pressure plate 5; the press The rear outer surface of the plate frame 1 of the last filter plate frame of the machine body presses against the front outer surface of the push plate 11; the top of the piston rod of the large oil cylinder 3 presses against the rear outer surface of the push plate 11; the feeding system includes a feed pump 12 and a feed port 4; a feed port 4 (i.e., a central feed hole) is provided at the center of the frontmost filter plate frame of the press body; the feed pump 12 is connected to the feed port 4; the hydraulic system is used to supply oil to the small oil cylinder 2 and the large oil cylinder 3; the overflow valve on the oil inlet pipe of the small oil cylinder 2 in the hydraulic system is a proportional overflow valve 10.

[0032] The PLC control system includes a PLC controller; a feed pressure sensor 7 is provided at the feed port 4 of the press; a small cylinder pressure sensor 8 is provided at the oil inlet of the small cylinder 2; a large cylinder pressure sensor 9 is provided at the oil inlet of the large cylinder 3; the small cylinder feed pressure sensor 7, the small cylinder pressure sensor 8, and the large cylinder pressure sensor 9 are respectively connected to the input end of the PLC controller; the output end of the PLC controller is connected to a proportional relief valve 10 provided on the oil inlet pipeline of the small cylinder 2, and the pressure of the small cylinder 2 can be controlled by controlling the opening of the proportional relief valve 10.

[0033] like Figure 3 As shown, the feed pump 12 is driven by a variable frequency motor 13, and the output end of the PLC controller is connected to the variable frequency motor 13 that drives the feed pump 12. By controlling the working frequency of the variable frequency motor 13 that drives the feed pump 12, the speed of the feed pump 12 can be controlled (and the outlet flow of the feed pump 12 can be controlled at the same time), thereby controlling the feed speed.

[0034] Or, as Figure 4 As shown, the feed pump 12 is driven by hydraulic pressure, and the hydraulic drive device of the feed pump 12 is controlled by a hydraulic proportional valve 14 or a proportional relief valve 15 (that is, the flow of the hydraulic oil driving the feed pump 12 is controlled by the hydraulic proportional valve 14 or the proportional relief valve 15), and the output end of the PLC controller is connected to the hydraulic proportional valve 14 or the proportional relief valve 15 of the hydraulic drive device of the feed pump 12; by controlling the opening of the hydraulic proportional valve 14 or the proportional relief valve 15 of the hydraulic drive device of the feed pump 12, the speed of the feed pump 12 can be controlled (and the outlet flow of the feed pump 12 can be controlled at the same time), thereby controlling the feed speed.

[0035] according to Figure 1 and Figure 3 , the force analysis of the press plate frame is as follows:

[0036] P3×S3=(P1-ΔP)×S1+P2×S2 (Formula 1)

[0037] Plate-frame sealing force F=P2XS2-ΔPxS1 (Formula 2)

[0038] Where: ΔP is the resistance loss along the way, P1 is the feed pressure (i.e., the cake pressure), P2 is the small cylinder pressure, and P3 is the large cylinder pressure; S1 is the filtration area (i.e., the cake area, that is, the plate and frame area minus the sealing area S4), S2 is the sum of all small cylinder areas, S3 is the large cylinder area, and S4 is the sealing area (i.e., the area of ​​the sealing surface); F is the plate and frame sealing force; this plate and frame sealing force F acts on the sealing area S4 to achieve a sealing effect.

[0039] like Figure 2As shown, filtration area S1 = plate frame area - sealing area S4; plate frame area = plate frame perimeter length × plate frame perimeter width - area of ​​central feed hole 4; area of ​​central feed hole 4 = π × (d / 2)². Sealing area S4 = actual pressure-bearing area of ​​the plate frame's load-bearing surface.

[0040] According to the above formula 2, when ΔP is too large, the plate-frame sealing force F will be reduced too much, resulting in material spraying. Now, the A value is set as a maximum limit of ΔP×S1. The A value is the maximum value that the original sealing force value P2XS2 can be weakened. When the A value is reached, the feeding is stopped and the pressing process begins. It can be seen that by setting the A value, the sealing force F can be kept within a reasonable range to prevent material spraying.

[0041] The calculation formula of ΔP along-the-line resistance loss is:

[0042] Where: λ is the drag coefficient along the way; (the drag coefficient λ along the way is related to the chemical composition, density, viscosity, and pipe roughness of the material - that is, it is related to the composition and degree of conditioning of the material)

[0043] l is the length of the central feed hole, d is the diameter of the central feed hole;

[0044] ρ is the density of the material, and v is the feed rate of the material.

[0045] According to the above formula 3, we can see that:

[0046] (1) When the material and pipeline roughness are the same, the resistance coefficient λ and the density ρ of the material are constant. The factors affecting ΔP are: the length l of the center feed hole (related to the number of plates and frames), the diameter d of the center feed hole, and the feed speed v of the material.

[0047] (2) When the same press equipment is used, the length l and the diameter d of the central feed hole are constant. The factors affecting ΔP are: the resistance coefficient λ along the way, the density ρ of the material, and the feed speed v of the material.

[0048] The drag coefficient λ and the material density ρ are determined by the material composition and conditioning, while the material feed rate v can be controlled. To reduce ΔP, two methods can be used: (a) controlling the number of plates and frames, that is, controlling the center feed hole length l within the range of 5600mm±100mm while appropriately increasing the center feed hole diameter d; (b) reducing the number of plates and frames to reduce l (the center feed hole length l can be reduced by 10-15%, from the original 5600mm±100mm to 5000±100mm). However, it is best to increase the area of ​​the plates and frames accordingly to ensure that the total filtration area S1 remains unchanged when the center feed hole length l is reduced. Taking into account the contradiction between the filtration area and the reduction of ΔP, the diameter d of the central feed hole can be appropriately increased. In the present invention, the diameter d of the press feed port (i.e., the central feed hole) 4 is designed to be increased by 55-65%, from the original 120mm±10mm to 200mm±20mm. At the same time, the feed speed v is controlled during the feeding process to achieve the effect of reducing ΔP.

[0049] According to Formula 2, when the sum of the areas S2 of all small cylinders is fixed, increasing the small cylinder pressure P2 value can increase the sealing force F value and reduce the occurrence of mud spraying. By increasing the small cylinder pressure P2 value, the relief valve on the oil inlet pipe of the small cylinder in the original hydraulic system can be replaced with a proportional relief valve 10, and the PLC controller controls the opening of the proportional relief valve 10 to control the size of the small cylinder pressure P2 value.

[0050] The feed pressure sensor 7, the small oil cylinder pressure sensor 8, and the large oil cylinder pressure sensor 9 are respectively connected to the input end of the PLC controller; the output end of the PLC controller is connected to the proportional relief valve 10 provided on the oil inlet pipeline of the small oil cylinder 2; by controlling the opening of the proportional relief valve 10, the pressure of the small oil cylinder can be controlled.

[0051] The output of the PLC controller is also connected to the variable frequency motor 13 that drives the feed pump 12, or to the hydraulic proportional valve 14 or proportional relief valve 15 of the hydraulic drive system of the feed pump 12. The feed pump 12 is driven by the variable frequency motor 13, and the speed of the feed pump 12 can be controlled by controlling the operating frequency of the variable frequency motor 13 that drives the feed pump (and the outlet flow rate of the feed pump 12 can be controlled, thereby controlling the feed speed v); alternatively, the feed pump 12 is driven by hydraulic pressure, and the hydraulic drive system of the feed pump 12 is controlled by the hydraulic proportional valve 14 or proportional relief valve 15 (i.e., the flow rate of the hydraulic oil driving the feed pump 12 is controlled by the hydraulic proportional valve 14 or proportional relief valve 15), and the speed of the feed pump 12 can be controlled by controlling the opening of the hydraulic proportional valve 14 or proportional relief valve 15 of the hydraulic drive device of the feed pump 12; in this way, the PLC controller can control the speed of the feed pump 12 (and the outlet flow rate of the feed pump 12), that is, it can control the feed speed v.

[0052] The present invention provides a blowout prevention control method for a press feed, which is to add a blowout prevention monitoring program to a PLC control program. That is, an A value, i.e., a maximum limit value of ΔP×S1, is set in the PLC control program, wherein ΔP is the resistance loss along the way, and S1 is the filtration area, i.e., the plate frame area minus the sealing area S4. When the press is actually running, during the material feeding process, the real-time pressure values ​​of P1, P2, and P3 are collected by the feed pressure sensor, the small oil cylinder pressure sensor, and the large oil cylinder pressure sensor. The value of ΔP×S1, i.e., the value B, is continuously calculated by the operator in the PLC controller. Once the actual working value of ΔP×S1, i.e., the value B, exceeds the set A value, the feeding is stopped and the pressing is performed. Thus, the feed pressure, small oil cylinder pressure, and feed flow rate are automatically adjusted by the pressure values ​​of P1, P2, and P3 fed back by the feed pressure sensor, the small oil cylinder pressure sensor, and the large oil cylinder pressure sensor. This monitors the operation of the equipment and prevents blowout.

[0053] The specific implementation method of the press feed blowout prevention control of the present invention is as follows:

[0054] An A value is set in the PLC control program, which is a maximum limit value of ΔP×S1; and a calculation formula for calculating the real-time value B of ΔP×S1 is compiled into the PLC control program: B=P1×S1+P2×S2-P3×S3; during the material feeding process, the PLC controller continuously collects the values ​​of the feed pressure sensor 7, the small cylinder pressure sensor 8, and the large cylinder pressure sensor 9, which are the values ​​of the feed pressure P1, the small cylinder pressure P2, and the large cylinder pressure P3 respectively. Then, the operator in the PLC controller performs continuous calculations according to the B value calculation formula: B=P1×S1+P2×S2-P3×S3 to obtain the B value, and compares the calculated B value (real-time value of ΔP×S1) with the set A value (maximum limit value of ΔP×S1); if the B value is close to the A value, the PLC controller controls the working frequency of the variable frequency motor 13 that drives the feed pump 12 or controls the hydraulic proportional valve 14 or proportional overflow valve of the hydraulic drive device of the feed pump 12. The opening of the flow valve 15 reduces the speed of the feed pump, thereby reducing the feed speed v; at the same time, the PLC controller controls the opening of the proportional relief valve 10 on the oil inlet pipe of the small oil cylinder 2 to increase the small oil cylinder pressure P2 value; when the feed speed v is reduced to the minimum value (this minimum value is determined by the characteristics of the feed pump), and the small oil cylinder pressure P2 value increases to the maximum value (the maximum value of the small oil cylinder pressure P2 value is determined by the pressure resistance value of the small oil cylinder; usually, in the initial mud feeding condition, the small oil cylinder pressure P2 value is controlled at about 14MPa, and when the B value increases to close to the A value, the small oil cylinder pressure P2 value increases to about 20MPa under the control of the PLC controller), the B value still rises; when the B value ≥ the A value, the PLC controller controls the feed pump to stop running, the press ends feeding, and enters the pressing program. Therefore, the feed pressure, small oil cylinder pressure and feed flow rate are automatically adjusted through the P1, P2 and P3 pressure values ​​fed back by the feed pressure sensor, small oil cylinder pressure sensor and large oil cylinder pressure sensor, thereby monitoring the operation of the equipment and preventing material spraying.

[0055] In summary, by adopting the above monitoring method, as long as the relationship between the B value (i.e. the real-time value of ΔP×S1), the small cylinder pressure P2 value, and the feed speed v is monitored well, the purpose of effectively preventing blowout can be achieved.

Claims

1. A press feed blowout prevention control device, characterized in that: It includes: The press body, feeding system, hydraulic system and PLC control system; the press body includes a number of filter plate frames arranged in sequence; each filter plate frame includes a plate frame and a pressure plate, the plate frame is covered with filter cloth, and a number of small oil cylinders are arranged around the plate frame and the pressure plate, the cylinder body of the small oil cylinder is arranged in the plate frame, and the top of the piston rod of the small oil cylinder is against the pressure plate; the rear outer surface of the plate frame of the last filter plate frame of the press body is against the front outer surface of the push plate; the top of the piston rod of the large oil cylinder is against the rear outer surface of the push plate; the feeding system includes a feed pump and a feed port; a feed port is arranged in the center of the frontmost filter plate frame of the press body; the feed pump is connected to the feed port; the hydraulic system is used for oil supply to the small oil cylinder and the large oil cylinder; the overflow valve on the oil inlet pipe of the small oil cylinder in the hydraulic system is a proportional overflow valve; The PLC control system includes a PLC controller; a feed pressure sensor is provided at the feed port of the press or the outlet of the feed pump; a small oil cylinder pressure sensor is provided at the oil inlet of the small oil cylinder; and a large oil cylinder pressure sensor is provided at the oil inlet of the large oil cylinder; the feed pressure sensor, the small oil cylinder pressure sensor, and the large oil cylinder pressure sensor are respectively connected to the input end of the PLC controller; the output end of the PLC controller is connected to a proportional relief valve provided on the oil inlet pipeline of the small oil cylinder, and the pressure of the small oil cylinder can be controlled by controlling the opening of the proportional relief valve; the output end of the PLC controller is connected to a motor driving the feed pump, or connected to a proportional valve of a hydraulic drive device of the feed pump; the feed speed can be controlled by controlling the rotation speed of the motor driving the feed pump, or controlling the opening of the proportional valve of the hydraulic drive device of the feed pump; The diameter d of the press feed opening, i.e. the central feed hole, is designed to be increased by 55-65%; The length l of the central feed hole of the press is designed to be reduced by 10-15%.

2. The press feed blowout prevention control device according to claim 1, characterized in that: The feed pump is driven by a variable frequency motor, and the output end of the PLC controller is connected to the variable frequency motor driving the feed pump; by controlling the working frequency of the variable frequency motor driving the feed pump, the speed of the feed pump can be controlled, thereby controlling the feed speed.

3. The press feed blowout prevention control device according to claim 1, characterized in that: The feed pump is driven hydraulically, and the hydraulic drive device of the feed pump is controlled by a hydraulic proportional valve or a proportional relief valve. The output end of the PLC controller is connected to the hydraulic proportional valve or the proportional relief valve of the hydraulic drive device of the feed pump; by controlling the opening of the hydraulic proportional valve or the proportional relief valve of the hydraulic drive device of the feed pump, the speed of the feed pump can be controlled, thereby controlling the feed speed.

4. A method for controlling feed blowout prevention of a press using the feed blowout prevention control device for a press as claimed in any one of claims 1 to 3, characterized in that: A blowout prevention monitoring program is added to the PLC control program, that is, an A value is set in the PLC control program, that is, the maximum value of ΔP×S1, wherein ΔP is the resistance loss along the way, and S1 is the filtering area, that is, the plate frame area minus the sealing area S4; when the press is actually running, during the material feeding process, the real-time pressure values ​​of the feed pressure P1, the small cylinder pressure P2, and the large cylinder pressure P3 are collected through the feed pressure sensor, the small cylinder pressure sensor, and the large cylinder pressure sensor, and the value of ΔP×S1, that is, the B value, is continuously calculated through the operator in the PLC controller. Once the actual working ΔP×S1 value, that is, the B value, exceeds the set A value, the feeding is stopped and the pressing is performed; thus, the feed pressure, the small cylinder pressure, and the feed flow rate are automatically adjusted through the P1, P2, and P3 pressure values ​​fed back by the feed pressure sensor, the small cylinder pressure sensor, and the large cylinder pressure sensor; thereby monitoring the operation of the equipment to prevent blowout.

5. The press feed blowout prevention control method according to claim 4, characterized in that: Set an A value in the PLC control program, that is, a maximum limit value of ΔP×S1; and program the calculation formula of the real-time value B of ΔP×S1 into the PLC control program: B=P1×S1+P2×S2-P3×S3; where S1 is the filter area, S2 is the sum of the areas of all small cylinders, and S3 is the area of ​​the large cylinder; in the process of material feeding, the PLC controller continuously collects the values ​​of the feed pressure sensor, the small cylinder pressure sensor, and the large cylinder pressure sensor, which are the values ​​of the feed pressure P1, the small cylinder pressure P2, and the large cylinder pressure P3 respectively, and then, the operator in the PLC controller continuously operates according to the B value calculation formula: B=P1×S1+P2×S2-P3×S3 Calculate to get the B value, and compare the calculated B value, i.e. the real-time value of ΔP×S1, with the set A value, i.e. the maximum limit value of ΔP×S1; if the B value is close to the A value, the PLC controller controls the operating frequency of the motor driving the feed pump or controls the opening of the proportional valve of the hydraulic drive device of the feed pump to reduce the speed of the feed pump, thereby reducing the feed speed v; at the same time, the PLC controller controls the opening of the proportional relief valve on the oil inlet pipe of the small oil cylinder to increase the small oil cylinder pressure P2 value; when the feed speed v is reduced to the minimum value and the small oil cylinder pressure P2 value is increased to the maximum value, the B value still rises; when the B value ≥ the A value, the PLC controller controls the feed pump to stop running, the press ends feeding, and enters the pressing program.

Images