An explosion-proof hydraulic cylinder and a plate-and-frame filter press

Abstract

The present invention discloses an explosion-proof hydraulic cylinder and a plate-frame filter press, specifically relating to the technical field of hydraulic components, including a cylinder block, a piston, and a piston rod. An oil inlet pipe and an oil outlet pipe are provided on the outer wall of the cylinder block. It also includes a connecting part and a buffer part, and deformation joints are provided on the periphery of the buffer part; a connecting seat, the connecting seat is sleeved on the connecting part, a retaining cover is fixedly connected to the end of the connecting seat, a perforation for the piston rod to freely pass through is coaxially provided on the retaining cover, and a spacer ring is fixedly sleeved on one end of the piston rod penetrating into the installation cavity. By providing the buffer part and the connecting seat, when the movement stroke of the piston rod is relatively large, the buffer part will slide in the tapered hole of the connecting seat, so that the inner wall of the tapered hole generates a squeezing force on the buffer part, thereby causing the buffer part to generate elastic shrinkage deformation. At the same time, the buffer part generates horizontal movement, thereby buffering the piston rod. Thus, when the hydraulic pressure of the hydraulic cylinder is relatively large, the piston rod can move slightly, thereby achieving the purpose of buffering and avoiding excessive pressure on the plate frame of the filter press.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic components, and more specifically, to an explosion-proof hydraulic cylinder and a plate-and-frame filter press. Background Art

[0002] The dehydration principle of a plate-and-frame filter press: The plates and frames are arranged alternately. Filter cloths are covered on both sides of the filter plates. The plates and frames are tightened by a pressing device, thus forming a filter pressing chamber between the plates and frames. Small holes are opened at the same position in the middle of the upper ends of the plates and frames. After being tightened, they form a passage. The sludge pressurized to 0.2 - 0.4 MPa enters the filter pressing chamber through this passage. The surface of the filter plate is engraved with grooves, and holes for discharging filtrate are drilled at the lower end. Under pressure, the filtrate passes through the filter cloth, along the grooves and the holes, and is discharged from the filter press, dehydrating the sludge.

[0003] The pressing device of the filter press mainly uses a hydraulic cylinder as the driving source to drive the movement of the plate-and-frame. For the seal between the plate-and-frame, the hydraulic pressure of the hydraulic cylinder is usually large, resulting in a large pressing force on the surfaces of adjacent plates and frames. If the instantaneous pressure of the hydraulic cylinder is too large, it will cause the pressing force between the plate-and-frame to be too large, which may further cause the plate-and-frame to deform, affecting the sealing performance between the plate-and-frame, and further affecting the filtering accuracy. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides an explosion-proof hydraulic cylinder and a plate-and-frame filter press. The technical problem to be solved by the present invention is that: in the prior art, the hydraulic pressure of the hydraulic cylinder of the filter press is usually large, resulting in a large pressing force on the surfaces of adjacent plates and frames. If the instantaneous pressure of the hydraulic cylinder is too large, it will cause the pressing force between the plate-and-frame to be too large, which may further cause the plate-and-frame to deform, affecting the sealing performance between the plate-and-frame, and further affecting the filtering accuracy.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An explosion-proof hydraulic cylinder, comprising a cylinder body, a piston and a piston rod. The piston divides the interior of the cylinder body into a first oil chamber and a second oil chamber in sequence. An oil inlet pipe communicating with the first oil chamber and an oil outlet pipe communicating with the second oil chamber are provided on the outer wall of the cylinder body. It further includes:

[0007] A connecting part, which is fixedly connected to the end of the piston rod. A buffer part is coaxially connected to the end of the connecting part away from the cylinder body. The outer diameter of the buffer part decreases sequentially in the direction away from the connecting part. A plurality of deformation seams extending to the periphery of the connecting part are provided on the periphery of the buffer part;

[0008] Connecting seat, the connecting seat is sleeved on the connecting part, the connecting seat is provided with an installation cavity for the insertion and fitting of the connecting part, and a tapered hole for the engagement of the buffer part. A retaining cover is fixedly connected to the end of the connecting seat. The retaining cover is coaxially provided with a through hole for the free passage of the piston rod. One end of the piston rod passing into the installation cavity is fixedly sleeved with a spacer ring. The two end faces of the spacer ring respectively abut against the end face of the connecting part and the end face of the spacer ring.

[0009] Further, a plurality of the deformation joints are arranged in an axial array along the connecting part. The connecting part and the buffer part are integrally formed structures and are made of spring steel material.

[0010] Further, an adjusting seat is fixedly connected to the periphery of the connecting seat. The adjusting seat is hollow inside and is provided with a first connection port and a second connection port on its outer wall. The first connection port is connected to the oil inlet pipe, and the second connection port is connected to the main oil pipe. An adjusting piston is engaged in the adjusting seat. The adjusting piston freely slides radially along the connecting seat in the adjusting seat. An adjusting unit is provided on the adjusting seat. The adjusting unit is used to drive the adjusting piston to move upward when the spacer ring moves towards the buffer part.

[0011] Further, the adjusting unit includes a sliding column coaxially fixed to the lower end face of the adjusting piston. The sliding column freely slides vertically on the connecting seat. A ball is rotatably installed at the lower end of the sliding column. A wedge block is fixedly connected to the periphery of the spacer ring. The ball is in rolling connection with the inclined surface of the wedge block.

[0012] Further, a return spring is vertically installed in the adjusting seat. The two ends of the return spring in the direction of the elastic force respectively elastically abut against the adjusting piston and the inner top wall of the adjusting seat in a one-to-one correspondence manner.

[0013] Further, a blind hole is coaxially opened on one end face of the piston facing the first oil chamber. A pressure relief sliding plug is engaged in the blind hole. The pressure relief sliding plug freely slides in the blind hole. A pressure relief unit for driving the pressure relief sliding plug to move is provided on the piston rod.

[0014] Further, a flange with an inward turn is provided at the orifice of the blind hole. The inner diameter of the flange is smaller than the outer diameter of the pressure relief sliding plug.

[0015] Further, the pressure relief unit includes a protrusion coaxially and fixedly connected to the end face of the pressure relief sliding plug. The piston rod is coaxially provided with a mounting hole in the form of a through hole. A driving rod is inserted into the mounting hole. The driving rod is rotatably connected to the piston. One end of the driving rod inserted into the piston is threadedly inserted into the protrusion. The other end of the driving rod penetrates into the buffer portion and freely slides within the buffer portion. A rotating assembly is provided within the connecting seat. The rotating assembly is configured to drive the driving rod to rotate when the buffer portion slides within the connecting seat.

[0016] Further, the rotating assembly includes a driving ball rotatably fitted at the end of the driving rod. A fixing column is coaxially and fixedly connected within the connecting seat. The buffer portion is coaxially provided with an avoidance hole for the fixing column to freely pass through. The end of the fixing column is coaxially provided with a sliding hole for the driving rod to freely pass through. A spiral rolling groove for the driving ball to engage is provided on the inner wall of the sliding hole. The driving ball freely rolls within the spiral rolling groove.

[0017] A plate and frame filter press includes the explosion-proof hydraulic cylinder as described above.

[0018] The technical effects and advantages of the present invention:

[0019] 1. By providing the buffer portion and the connecting seat, when the piston rod has a large movement stroke, the buffer portion will slide within the tapered hole of the connecting seat, causing the inner wall of the tapered hole to exert an extrusion force on the buffer portion, thereby causing the buffer portion to undergo elastic contraction deformation. At the same time, the buffer portion undergoes horizontal movement, enabling the piston rod to have buffering. Thus, when the hydraulic pressure of the hydraulic cylinder is large, the piston rod can undergo a small amplitude of movement, thereby achieving the purpose of buffering and avoiding excessive pressure on the plate and frame of the filter press.

[0020] 2. By providing the wedge block, the sliding column, and the ball, when the buffer portion moves away from the cylinder block, the ball will roll from the lower side to the upper side of the inclined surface of the wedge block, thereby driving the sliding column to move upward, causing the adjusting piston to move upward within the adjusting seat, and enabling the periphery of the adjusting piston to partially block the openings of the first connection port and the second connection port, thereby reducing the oil intake of the cylinder block, decreasing the hydraulic pressure of the cylinder block, and avoiding large forces acting on the piston rod.

[0021] 3. By providing the pressure relief sliding plug, when the buffer portion moves away from the cylinder block, the driving ball will roll within the spiral rolling groove, thereby driving the driving rod to rotate. When the driving rod rotates, it will cause the driving rod and the protrusion to undergo threaded engagement, thereby causing the protrusion to drive the pressure relief sliding plug to move towards the inner side of the piston, thereby increasing the internal volume of the first oil chamber, and thus being able to reduce the hydraulic pressure of the hydraulic cylinder to a certain extent. Description of the Drawings

[0022] Figure 1 Structural schematic diagram of an explosion-proof hydraulic cylinder in the present invention;

[0023] Figure 2 is Figure 1 Side view angle structural schematic diagram;

[0024] Figure 3 is Figure 2 Cross-sectional structural schematic diagram;

[0025] Figure 4 is Figure 3 Front view angle structural schematic diagram;

[0026] Figure 5 is Figure 4 Enlarged schematic diagram of the local structure at A in;

[0027] Figure 6 Structural schematic diagram of the piston, piston rod and connecting seat after assembly in the present invention;

[0028] Figure 7 is Figure 6 Cross-sectional schematic diagram of the structure in;

[0029] Figure 8 is Figure 7 Enlarged schematic diagram of the local structure at B in;

[0030] Figure 9 is Figure 7 Enlarged schematic diagram of the local structure at C in;

[0031] Figure 10 Structural schematic diagram of the connecting part and the buffer part after assembly in the present invention;

[0032] Figure 11 is Figure 10 Side view angle structural schematic diagram.

[0033] Reference numerals are: 1, connecting seat; 2, piston rod; 3, main oil pipe; 4, adjusting seat; 5, inlet oil pipe; 6, cylinder block; 7, outlet oil pipe; 8, retaining cover; 9, pressure relief sliding plug; 10, piston; 11, spacer ring; 12, wedge block; 13, connecting part; 14, fixing column; 15, tapered hole; 16, driving rod; 17, first connection port; 18, return spring; 19, adjusting piston; 20, sliding column; 21, ball; 22, avoidance hole; 23, protruding part; 24, flange; 25, driving ball; 26, spiral rolling groove; 27, deformation joint; 28, buffer part. Detailed implementation manners

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] As Figures 1 - 11 shown, in this embodiment, there is disclosed an explosion-proof hydraulic cylinder, which is used in conjunction with a plate-frame filter press. The hydraulic cylinder includes a cylinder block 6, a piston 10, and a piston rod 2. One end of the piston rod 2 that penetrates into the cylinder block 6 is coaxially fixed to the end face of the piston 10, and the other end thereof penetrates out of the cylinder block 6. The piston 10 divides the interior of the cylinder block 6 into a first oil chamber and a second oil chamber in sequence. An oil inlet pipe 5 communicating with the first oil chamber and an oil outlet pipe 7 communicating with the second oil chamber are provided on the outer wall of the cylinder block 6. The oil outlet pipe 7 is connected to the hydraulic station of the filter press. A connecting seat 1 is connected to the plate-frame of the plate-frame filter press by screws. An installation cavity is coaxially provided in the connecting seat 1. A connecting portion 13 is coaxially engaged in the installation cavity and can freely slide axially along the connecting seat 1 in the installation cavity. One end of the piston rod 2 that penetrates out of the cylinder block 6 is coaxially connected to the connecting portion 13. A retaining cover 8 is fixedly connected to the connecting seat 1. A through hole for the piston rod 2 to freely pass through is coaxially provided in the retaining cover 8. A spacer ring 11 is fixedly sleeved on one end of the piston rod 2 that penetrates into the installation cavity. The two end faces of the spacer ring 11 respectively abut against the end face of the connecting portion 13 and the end face of the spacer ring 11. In addition, a buffer portion 28 is coaxially provided at one end of the connecting portion 13 away from the piston rod 2. The outer diameter of the buffer portion 28 gradually decreases in the direction away from the connecting portion 13. A tapered hole 15 for engaging the buffer portion 28 is provided in the connecting seat 1. A plurality of deformation slots 27 extending to the periphery of the connecting portion 13 are provided on the periphery of the buffer portion 28. The plurality of deformation slots 27 are arranged in an axial array along the connecting portion 13.

[0036] The hydraulic station of the filter press supplies oil to the inlet pipe 5, increasing the oil pressure in the first oil chamber. The hydraulic oil in the second oil chamber flows back to the hydraulic station via the outlet pipe 7, generating a thrust on the piston 10. As a result, the piston 10 drives the piston rod 2 to extend out of the cylinder block 6, further driving the movement of the drive connection part 13, causing the piston rod 2 to drive the plate frames to move, and enabling the plate frames to be tightly pressed against each other. When the hydraulic pressure is too high, the length of the piston rod 2 extending out of the cylinder block 6 exceeds the tolerance. At this time, the plate frames cannot move further, that is, the connecting seat 1 will be in a static state. Therefore, the buffer part 28 will move slightly, causing relative sliding between the periphery of the buffer part 28 and the inner wall of the tapered hole 15. The inner wall of the tapered hole 15 generates a squeezing force along the radially inner side of the buffer part 28 on the periphery of the buffer part 28, causing the buffer part 28 to undergo elastic contraction deformation. At the same time, the buffer part 28 moves slightly horizontally within the tapered hole 15. Relying on the elastic deformation and horizontal movement of the buffer part 28, the movement of the piston rod 2 is buffered. Additionally, the connection part 13 and the buffer part 28 are integrally formed structures and are made of spring steel material, ensuring that no plastic deformation occurs when the buffer part 28 undergoes elastic deformation;

[0037] The periphery of the connecting seat 1 is integrally formed with an adjusting seat 4. The adjusting seat 4 is hollow inside and has a first connection port 17 and a second connection port on its outer wall. The first connection port 17 and the second connection port are coaxial. The first connection port 17 is connected to the inlet pipe 5, and the second connection port is connected to a main oil pipe 3. The main oil pipe 3 is connected to the outlet of the hydraulic station. An adjusting piston 19 is engaged in the adjusting seat 4. The adjusting piston 19 slides freely along the radial direction of the connecting seat 1 within the adjusting seat 4. The lower end face of the adjusting piston 19 is coaxially and fixedly connected to a sliding column 20. The sliding column 20 slides freely vertically on the connecting seat 1. A ball 21 is rotatably installed at the lower end of the sliding column 20. A wedge block 12 is fixedly connected to the periphery of the spacer ring 11. The ball 21 is in rolling connection with the inclined surface of the wedge block 12. As Figure 5 shown, the height of the inclined surface of the wedge block 12 decreases successively from left to right. A return spring 18 is vertically installed in the adjusting seat 4. The two ends of the return spring 18 in the direction of its elastic force elastically abut against the adjusting piston 19 and the inner top wall of the adjusting seat 4 respectively;

[0038] In the initial state, the return spring 18 generates a downward elastic abutting force on the adjusting piston 19, causing the sliding column 20 to drive the adjusting piston 19 to move downward, enabling the ball 21 to be in rolling connection with the inclined surface of the wedge block 12. At this time, the periphery of the adjusting piston 19 does not block the mouths of the first connection port 17 and the second connection port. When the buffer part 28 moves in the direction away from the cylinder block 6, it will drive the spacer ring 11 to move, causing the ball 21 to roll from the lower side to the upper side of the inclined surface of the wedge block 12, further driving the sliding column 20 to move upward, causing the periphery of the adjusting piston 19 to partially block the mouths of the first connection port 17 and the second connection port, thereby reducing the amount of hydraulic oil transported by the hydraulic station into the cylinder block 6 and decreasing the hydraulic pressure of the hydraulic cylinder;

[0039] One end face of the piston 10 facing the first oil chamber is coaxially provided with a blind hole, in which a pressure relief sliding plug 9 is clamped. The pressure relief sliding plug 9 slides freely in the blind hole. The orifice of the blind hole is provided with an inwardly turned flange 24. The inner diameter of the flange 24 is smaller than the outer diameter of the pressure relief sliding plug 9. The flange 24 can limit the movement of the pressure relief sliding plug 9 towards the orifice of the blind hole. A protruding portion 23 is coaxially and fixedly connected to the end face of the pressure relief sliding plug 9. The piston rod 2 is coaxially provided with a mounting hole in the form of a through hole. A driving rod 16 is inserted into the mounting hole. Both axial ends of the driving rod 16 pass through the piston rod 2. The driving rod 16 is rotatably connected to the piston 10. One end of the driving rod 16 inserted into the piston 10 is threadedly inserted into the protruding portion 23. The other end of the driving rod 16 is inserted into the buffer portion 28 and slides freely in the buffer portion 28. Driving balls 25 are symmetrically and rotatably fitted at the end of the driving rod 16 along its axis. A fixed column 14 is coaxially and fixedly connected in the connecting seat 1. The buffer portion 28 is coaxially provided with an avoidance hole 22 for the fixed column 14 to pass through freely. The end of the fixed column 14 is coaxially provided with a sliding hole for the driving rod 16 to pass through freely. A spiral rolling groove 26 for the driving balls 25 to engage is formed in the wall of the sliding hole. The driving balls 25 roll freely in the spiral rolling groove 26.

[0040] The working principle of the present invention: The oil pump of the hydraulic station of the filter press transports hydraulic oil to the main oil pipe 3, and then enters the regulating seat 4 from the main oil pipe 3. The hydraulic oil then flows into the inlet oil pipe 5 from the first connection port 17, and then into the first oil chamber. In addition, the hydraulic oil in the second oil chamber flows back to the hydraulic station through the outlet oil pipe 7. Thus, the pressure of the hydraulic oil in the first oil chamber drives the piston 10 to move towards the outside of the cylinder block 6. Then, the piston 10 drives the piston rod 2 to move. The piston rod 2 drives the connecting portion 13 to move, so that the connecting portion 13 drives the connecting seat 1 to move. The connecting seat 1 will synchronously drive the plate frame of the filter press to move. When adjacent plate frames abut against each other, if the pressure of the hydraulic cylinder is too high, the movement stroke of the piston rod 2 extending out of the cylinder block 6 is relatively large, and the plate frame cannot move continuously. Therefore, when the piston rod 2 continues to extend, it will cause the connecting portion 13 to drive the buffer portion 28 to move towards the inner side of the conical hole 15. During the movement, relative sliding occurs between the periphery of the buffer portion 28 and the inner wall of the conical hole 15. The inner wall of the conical hole 15 generates a squeezing force along the radially inner side of the buffer portion 28 on the periphery of the buffer portion 28. Thus, the buffer portion 28 generates an elastic contraction deformation. At the same time, the buffer portion 28 moves slightly horizontally in the conical hole 15. Relying on the elastic deformation and horizontal movement of the buffer portion 28, the movement of the piston rod 2 is buffered.

[0041] When the buffer part 28 moves in the direction away from the cylinder block 6, it will drive the spacer ring 11 to move, so that the ball 21 rolls from the lower side of the inclined surface of the wedge block 12 to the upper side, and then drives the sliding column 20 to move upward, so that the peripheral part of the adjusting piston 19 partially blocks the first connection port 17 and the port of the second connection port, thereby reducing the amount of hydraulic oil delivered to the cylinder block 6 by the hydraulic station, reducing the hydraulic pressure of the hydraulic cylinder. Additionally, synchronously, the drive rod 16 will move towards the inner side of the avoidance hole 22, and then the drive ball 25 rolls in the spiral rolling groove 26, driving the drive rod 16 to rotate, so that the drive rod 16 is threadedly engaged with the protruding part 23, and the protruding part 23 drives the pressure relief sliding plug 9 to move towards the inner side of the piston 10, thereby increasing the internal volume of the first oil chamber, and to a certain extent, reducing the hydraulic pressure of the hydraulic cylinder, that is, reducing the hydraulic pressure on the piston rod 2, and further reducing the movement stroke of the piston rod 2 extending out of the cylinder block 6, avoiding damage to the plate frame due to excessive extension length of the piston rod 2.

[0042] Finally, several points should be noted: First, in the description of the present application, it should be noted that unless otherwise specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, which can be mechanical connection or electrical connection, or the communication inside two components, and can be directly connected. "Up", "down", "left", "right", etc. are only used to represent relative position relationships. When the absolute position of the described object changes, the relative position relationship may change;

[0043] Second: In the drawings of the disclosed embodiments of the present invention, only the structures related to the disclosed embodiments are involved. Other structures can refer to the general design. Without conflict, the same embodiment and different embodiments of the present invention can be combined with each other;

[0044] Finally: The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An explosion-proof hydraulic cylinder, comprising a cylinder body, a piston and a piston rod, wherein the piston divides the interior of the cylinder body into a first oil chamber and a second oil chamber in sequence, and an outer wall of the cylinder body is provided with an oil inlet pipe communicating with the first oil chamber and an oil outlet pipe communicating with the second oil chamber, characterized in that: Also includes: A connecting portion, the connecting portion is fixedly connected to the end of the piston rod, one end of the connecting portion away from the cylinder body is coaxially connected to a buffer portion, the outer diameter of the buffer portion decreases in sequence in a direction away from the connecting portion, and a plurality of deformation seams extending to the periphery of the connecting portion are provided on the periphery of the buffer portion; A connecting seat, the connecting seat is sleeved on the connecting part, the connecting seat is provided with an installation cavity for the connecting part to be inserted, and a tapered hole for the buffer part to be engaged, a stop cover is fixedly connected to the end of the connecting seat, the stop cover is coaxially provided with a through hole for the piston rod to pass freely, one end of the piston rod inserted into the installation cavity is fixedly sleeved with a spacer ring, and both end faces of the spacer ring abut against the end face of the connecting part and the end face of the spacer ring respectively; An adjusting seat is fixedly connected to the periphery of the connecting seat, the adjusting seat is hollow inside and has a first connecting port and a second connecting port on the outer wall, the first connecting port is connected to the oil inlet pipe, the second connecting port is connected to the main oil pipe, an adjusting piston is engaged in the adjusting seat, the adjusting piston slides freely in the adjusting seat along the radial direction of the connecting seat, an adjusting unit is provided on the adjusting seat, and the adjusting unit is used to drive the adjusting piston to move upward when the spacer ring moves toward the buffer portion; The regulating unit comprises a sliding column coaxially fixed to the lower end surface of the regulating piston, the sliding column slides vertically and freely on the connecting seat, a ball is rotatably embedded in the lower end of the sliding column, a wedge is fixed to the periphery of the spacer ring, and the ball is rollingly connected to the inclined surface of the wedge; A return spring is vertically installed in the adjustment seat, and two ends of the return spring in the elastic force direction elastically press against the adjustment piston and the inner top wall of the adjustment seat respectively and one by one.

2. The explosion-proof hydraulic cylinder according to claim 1, characterized in that: The plurality of deformation seams are arranged in an axial array along the connecting portion. The connecting portion and the buffer portion are an integrally formed structure and are made of spring steel.

3. The explosion-proof hydraulic cylinder according to claim 1, characterized in that: A blind hole is coaxially formed on one end face of the piston facing the first oil chamber, a pressure relief sliding plug is engaged in the blind hole, the pressure relief sliding plug slides freely in the blind hole, and a pressure relief unit for driving the pressure relief sliding plug to move is provided on the piston rod.

4. The explosion-proof hydraulic cylinder according to claim 3, characterized in that: The opening of the blind hole is provided with an inverted flange, and the inner diameter of the flange is smaller than the outer diameter of the pressure relief sliding plug.

5. The explosion-proof hydraulic cylinder according to claim 3, characterized in that: The pressure relief unit includes a protrusion coaxially fixed to the end surface of the pressure relief sliding plug, the piston rod is coaxially provided with a mounting hole in the form of a through hole, a driving rod is passed through the mounting hole, the driving rod is rotatably connected to the piston, one end of the driving rod that penetrates into the piston is threadedly passed through the protrusion, the other end of the driving rod penetrates into the buffer portion and slides freely in the buffer portion, a rotating assembly is provided in the connecting seat, and the rotating assembly is used to drive the driving rod to rotate when the buffer portion slides in the connecting seat.

6. The explosion-proof hydraulic cylinder according to claim 5, characterized in that: The rotating assembly includes a driving ball rotatably embedded in the end of the driving rod, a fixing column is coaxially fixed in the connecting seat, the buffer portion is coaxially provided with an avoidance hole for the fixed column to pass freely, the end of the fixed column is coaxially provided with a sliding hole for the driving rod to pass freely, the hole wall of the sliding hole is provided with a spiral rolling groove for the driving ball to engage, and the driving ball rolls freely in the spiral rolling groove.

7. A plate and frame filter press, characterized in that: Including the explosion-proof hydraulic cylinder described in claim 1.

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