Structure of main cylinder of large oil press, pressing tool and online replacement method of main cylinder pressing sleeve

Abstract

The present application belongs to the technical field of large oil press, and relates to a large oil press main cylinder pressure sleeve and an online replacement method of the large oil press main cylinder pressure sleeve. The main cylinder body (1-21) falls to a working position, and the upper die device and the lower die device are removed. The main cylinder body (1-21) is locked at the highest position, and the T-shaped screw rod (1-6) of the connecting block (1-5) between the main cylinder body (1-21) and the lifting cylinder (4) is removed. The lifting oil cylinder (1-4) falls into the process hole of the oil press lower beam (1-1). The main cylinder (1-2) is unlocked, the lifting cylinder (1-4) falls to the lowest position with the main cylinder body (1-21), and the pump is stopped. The lifting oil cylinder (2-1) rises and lifts the main cylinder body (1-21). The online replacement method of the large oil press main cylinder pressure sleeve has simple steps, and the online replacement method is adopted when the large oil press main cylinder pressure sleeve is replaced, so that the replacement efficiency of the main cylinder pressure sleeve is improved, and the damage of other parts in the replacement process of the main cylinder pressure sleeve is reduced.

Description

Technical Field

[0001] This invention belongs to the technical field of large hydraulic presses, and more specifically, it relates to a pressure sleeve for the main cylinder of a large hydraulic press. This invention also relates to a pressing tool and a method for online replacement of the pressure sleeve for the main cylinder of a large hydraulic press. Background Technology

[0002] In the wheel production process, large hydraulic presses are used to shape the wheel blanks. Therefore, the hydraulic press is a key piece of equipment in wheel production. Existing large hydraulic presses adopt a three-beam, double-sided column + prestressed tie rod type. The upper beam, movable crossbeam and lower beam of the three beams are coaxial from top to bottom. The lower surface of the upper beam and the upper surface of the lower beam are connected to the side columns. Four prestressed tie rods pass through the upper surface of the upper beam, the lower surface of the lower beam and the side columns, and are screwed on by locking nuts that are connected to the upper surface of the upper beam and the lower surface of the lower beam. The movable crossbeam supports the main cylinder body of the hydraulic press (hereinafter referred to as the main cylinder body). An upper mold device is fixedly mounted on the lower surface of the main cylinder body, and a lower mold device is fixedly mounted on the upper surface of the lower beam. The upper and lower parts of the main cylinder body are square flanges, and the middle part is cylindrical. X-slider blocks are chamfered around the perimeter of the square flanges. The X-slider blocks are slidably connected to the working slide plate on the side column of the hydraulic press, serving a guiding function. The main cylinder body is slidably connected to the main cylinder plunger fixed in the center of the upper beam. Lifting cylinders are installed on both sides of the upper flange of the main cylinder body. The plunger is screwed to the connecting blocks fixed on both sides of the flange on the upper part of the main cylinder body via a T-screw. The lifting cylinder body is fixed on the side column. The lifting cylinder is responsible for the return stroke of the movable crossbeam. When the hydraulic press is pressing, the main cylinder body is filled with oil, which generates relative movement with the main cylinder plunger fixed on the upper beam, driving the movable crossbeam to move downward, driving the upper mold device to descend to the set position. The upper and lower mold devices close the mold, completing the forming of the wheel blank. After pressing is completed, the main cylinder body stops filling with oil, the lifting cylinder fills with oil, and drives the movable crossbeam to rise to the original zero position. After the hydraulic press has been working for a period of time, due to wear of the X-slider and the influence of the levelness of the main cylinder body, relative friction occurs between the main cylinder pressure sleeve and the main cylinder plunger inside the main cylinder body, causing wear of the main cylinder pressure sleeve. When the wear reaches a certain amount, it will affect the service life of the main cylinder seal and may even lead to oil leakage from the main cylinder, requiring replacement of the main cylinder pressure sleeve. The conventional replacement method is as follows: lower the main cylinder body to the set position, support the main cylinder body, stop the pump, disengage the main cylinder flange pressure sleeve from the main cylinder body, remove the main cylinder seal, remove the upper beam locking nut of the hydraulic press prestressed tie rod, and lift out... The process involves lifting the upper beam and main cylinder plunger, removing the main cylinder flange sleeve, and disassembling and reassembling the main cylinder flange sleeve. Following this reverse sequence, the components are installed before starting the pump. However, this method requires a high lifting height for the upper beam and main cylinder plunger, necessitates removing the roof of the hydraulic press workshop, and results in low efficiency, a large workload, and high replacement costs. This impacts wheel production efficiency. Furthermore, this method of replacing the main cylinder sleeve can damage the well-pressed mating surfaces between the hydraulic press's upper beam and side columns, and between the upper beam and the main cylinder plunger. This can cause some load-bearing surfaces of the hydraulic press to crush and be damaged, affecting the safe service life of the hydraulic press.

[0003] Existing technology includes a method for replacing the guide sleeve of a hydraulic cylinder in a large press forging process, with publication number CN117680966A. This method involves online separation of the hydraulic cylinder plunger and cylinder body based on the assembly characteristics of the hydraulic cylinder, and online disassembly and installation of the guide sleeve. The specific method is as follows: Online separation of the plunger and cylinder body before removing the return cylinder: The return cylinder is lowered, and the hydraulic cylinder plunger descends along with the movable crossbeam to the minimum stroke of the return cylinder. At this time, sleepers, shims, and jacks are placed inside the column to support the movable crossbeam. The return cylinder is then removed, and sleepers, shims, and jacks are placed at the original position of the return cylinder to support the movable crossbeam. Online separation of the plunger and cylinder body after removing the return cylinder: The hydraulic jack is operated, and shims and sleepers are continuously removed until the distance between the hydraulic cylinder plunger and cylinder body meets the working space for guide sleeve disassembly and installation. The guide sleeve is then removed and installed online. This method is efficient and convenient, significantly shortening the operation time and reducing the operation cost.

[0004] However, this technology does not address the technical issues and solutions of this application. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for online replacement of the main cylinder liner of a large hydraulic press, which is simple in procedure, adopts an online replacement method when replacing the main cylinder liner of the hydraulic press, improves the replacement efficiency of the main cylinder liner, and reduces the damage to other components during the replacement process.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] This invention relates to an online replacement method for the main cylinder pressure sleeve of a large hydraulic press. The replacement steps of the online replacement method for the main cylinder pressure sleeve of a large hydraulic press are as follows:

[0008] S1. The main cylinder body is lowered to the working position, and the upper mold device and lower mold device are removed;

[0009] S2: The main cylinder body is locked at the highest position. Remove the T-screw of the connecting block between the main cylinder body and the lifting cylinder.

[0010] S3: The lifting cylinder descends into the process hole of the lower beam of the hydraulic press;

[0011] S4: Master cylinder unlocks, lift cylinder falls back to the lowest position with the master cylinder body, pump stops;

[0012] S5: The lifting cylinder rises and lifts the main cylinder body;

[0013] S6: Remove the main cylinder flange press assembly and the connecting block 1-5 between the main cylinder body and the lifting cylinder. Hang the main cylinder flange press assembly on the upper beam of the hydraulic press using a hand chain hoist.

[0014] S7: The main cylinder body descends to the set working position along with the lifting cylinder and falls on the steel support frame. The lifting cylinder continues to descend to the lowest position.

[0015] S8: The master cylinder flange press sleeve assembly is lifted out through the longitudinal clearance between the master cylinder body and the master cylinder plunger, the master cylinder press sleeve is replaced, and then lifted in;

[0016] S9: Install the components on the master cylinder block in reverse order according to the steps above.

[0017] In step S2, remove the T-bolt of the connecting block between the main cylinder and the lifting cylinder: remove the two Haval protective rings at the bottom of the connecting block; remove the T-bolt nut at the top of the connecting block; the lifting cylinder falls back, exposing the spherical pad, and the T-bolt is pulled out; the lifting cylinder rises back to the top position, and the main cylinder is locked.

[0018] In step S5, when the lifting cylinder lifts the main cylinder body: open the valve on the lifting cylinder valve block of the hydraulic station, the pump starts to load, and the lifting cylinder slowly rises. When the top cap above the piston rod reaches the lower surface of the main cylinder body, the lifting cylinder rises again to lift the main cylinder body. Close the valve on the lifting cylinder valve block of the hydraulic station and observe whether the main cylinder body slides down. If so, check the hydraulic circuit and eliminate the source of the fault. When the main cylinder body is stable, stop the pump.

[0019] In step S7, when the main cylinder body descends to the set working position with the lifting cylinder: place a support frame below the main cylinder body, the height of which is the set height of the main cylinder descent position; after the connecting block is removed, oil enters the rodless chamber of the lifting cylinder; first open the throttle valve of the control cylinder on the lifting cylinder valve block, loosen it one turn, and observe whether the main cylinder body descends; if the main cylinder body does not descend, open the total return oil throttle valve on the valve block, loosen it one turn, and observe whether the main cylinder body descends; if the main cylinder body does not descend, open the total return oil safety relief valve on the valve block until the main cylinder body has a slow descent action; adjust the opening of each valve appropriately according to the descent speed of the main cylinder body; when the lower plane of the main cylinder body descends onto the support frame, oil enters the rod chamber of the lifting cylinder, driving the piston rod of the lifting cylinder back to the zero position, and then the pump stops and the power is cut off.

[0020] Step S8, during the disassembly and assembly of the main cylinder bushing: The main cylinder flange bushing assembly is lifted to a designated position through the longitudinal clearance between the main cylinder body and the main cylinder plunger, and the main cylinder bushing is removed; the mating surfaces of the main cylinder flange and the main cylinder bushing are machined to the required tolerance accuracy; the main cylinder bushing is machined according to the tolerance accuracy requirements of the main cylinder flange and the main cylinder bushing; the main cylinder bushing is assembled using a cryogenic press-fitting method, with liquid nitrogen cooling and press-fitting fixtures used for assembly. The press-fitting fixtures include a support plate, an adjusting screw, a pressure plate, and an adjusting nut. The pressure plate is connected to the upper part of the main cylinder bushing and also to the lower end of the adjusting nut. Threaded holes are machined at both ends of the support plate, and these threaded holes are connected to the lower part of the adjusting screw.

[0021] During the press-fitting process, the main cylinder flange is first placed on the press-fitting fixture support plate, and the adjusting screw is connected to the support plate. During this process, liquid nitrogen is used to cool the main cylinder press sleeve to the set assembly process dimensions. Then, the main cylinder press sleeve is hoisted to the mating surface with the main cylinder flange, and the pressure plate is hoisted to the upper surface of the main cylinder press sleeve. The adjusting screw passes through the through holes at both ends of the pressure plate, and by rotating the adjusting nut, the pressure plate is driven to move downward, causing the main cylinder press sleeve to be squeezed into the main cylinder flange, thus preventing indentations from being formed on the press-fitting surface during the press-fitting of the guide sleeve.

[0022] The press plate of the press-fitting fixture has concave positioning blocks at both ends of its contact portion with the guide sleeve, and the positioning blocks sit on the main cylinder press sleeve.

[0023] The positioning block is made of nylon, copper, rubber, or plastic.

[0024] The lifting cylinder raises the main cylinder body by 45mm-55mm.

[0025] The present invention also relates to a main cylinder structure of a large hydraulic press, including a lower beam of the hydraulic press, a main cylinder, an upper beam of the hydraulic press, a lifting cylinder, a connecting block, a T-screw, a lifting cylinder, and a support frame. The main cylinder includes a main cylinder body, a main cylinder flange, a main cylinder pressure sleeve, and a main cylinder plunger.

[0026] The present invention also relates to a press-fit fixture for the main cylinder sleeve of a large hydraulic press. The press-fit fixture 4 includes a support plate, an adjusting screw, a pressure plate, and an adjusting nut. The pressure plate is connected to the upper part of the main cylinder sleeve and is also connected to the lower end of the adjusting nut. The support plate has threaded holes machined at both ends, and the threaded holes are connected to the lower part of the adjusting screw.

[0027] The working principle and beneficial effects of the technical solution adopted in this invention are as follows:

[0028] The online replacement method for the main cylinder pressure sleeve of a large hydraulic press described in this invention includes the following steps: 1. When replacing the main cylinder pressure sleeve, the main cylinder body is disassembled from top to bottom. The main cylinder flange pressure sleeve assembly is lifted out for replacement. The replaced main cylinder flange pressure sleeve assembly is then reinstalled at the center of the hydraulic press, and installed from bottom to top along the pressing center line. This improves the efficiency of main cylinder pressure sleeve replacement, reduces damage to other components during cylinder guide sleeve replacement, extends the safe service life of the hydraulic press, saves replacement costs, ensures installation accuracy, and provides an operational standard for main cylinder pressure sleeve replacement. 2. The lifting cylinder uses a long-stroke hydraulic cylinder, allowing for one-time lifting without the need for an additional transition lifting rod. The up-and-down movement speed of the main cylinder body is controllable, resulting in low resistance during operation. A pad is provided at the piston head of the lifting cylinder to protect the piston rod head from deformation and damage caused by abnormal external forces. 3. The main cylinder bushing is assembled using a cryogenic pressing method, assisted by a pressing fixture. The pressing process is quick and convenient. An arc groove is provided below the pressing plate of the pressing fixture for easy positioning of the main cylinder bushing during pressing. A nylon positioning block is embedded in the arc groove where it contacts the main cylinder bushing, preventing indentations on the pressing surface when the main cylinder bushing is pressed into the main cylinder flange. This invention provides an online replacement method for the main cylinder bushing of a large hydraulic press. The steps are simple, and the online replacement method improves the efficiency of main cylinder bushing replacement and reduces damage to other components during the process. Attached Figure Description

[0029] The following is a brief explanation of the contents depicted in the accompanying drawings and the markings therein:

[0030] Figure 1 This is a schematic diagram of the main structure of the large hydraulic press described in this invention;

[0031] Figure 2 This is a schematic diagram of the axial view structure of the large hydraulic press described in this invention;

[0032] Figure 3 This is a schematic diagram of the axial view of the main cylinder of the large hydraulic press according to the present invention;

[0033] Figure 4 This is a schematic diagram of the press-fitting fixture described in this invention during use;

[0034] Figure 5 This is a schematic diagram of the press-fitting fixture described in this invention;

[0035] The labels in the attached diagram are as follows: 1-1, lower beam of the hydraulic press; 1-2, main cylinder; 1-3, ; 1-4, lifting cylinder; 1-5, connecting block; 1-6, T-screw; 1-21, main cylinder body; 1-22, main cylinder flange; 1-23, main cylinder pressure sleeve; 1-24, main cylinder plunger; 2-1, lifting cylinder; 2-2, top cap; 3, support frame; 4, pressing fixture; 4-1, support plate; 4-2, adjusting screw; 4-3, pressure plate; 4-4, adjusting nut. Detailed Implementation

[0036] The following description, with reference to the accompanying drawings, provides a more detailed explanation of the specific embodiments of the present invention, including the shape and structure of each component, the relative positions and connections between the parts, the functions and working principles of each part:

[0037] As attached Figure 1 -Appendix Figure 3 As shown, this invention provides a method for online replacement of the main cylinder pressure sleeve of a large hydraulic press. The replacement steps of this method are as follows:

[0038] S1. The main cylinder body 1-21 is lowered to the working position, and the upper mold device and lower mold device are removed; S2. The main cylinder body 1-21 is locked at the highest position, and the T-screw 1-6 of the connecting block 1-5 between the main cylinder body 1-21 and the lifting cylinder 1-4 is removed; S3. The lifting cylinder 2-1 is lowered into the process hole of the lower beam 1-1 of the hydraulic press; S4. The main cylinder 1-2 is unlocked, and the lifting cylinder 1-4 falls back to the lowest position with the main cylinder body 1-21, and the pump is stopped; S5. The lifting cylinder 2-1 rises and lifts the main cylinder body 1-21; S6. The main cylinder flange pressure fitting and the main cylinder are removed. The connecting block 1-5 between cylinder body 1-21 and lifting cylinder 1-4, and the main cylinder flange press fitting assembly are suspended from the upper beam 1-3 of the hydraulic press by a hand chain hoist; S7: The main cylinder body 1-21 descends to the set working position with the lifting cylinder 2-1 and falls on the steel support frame 3, and the lifting cylinder 2-1 continues to descend to the lowest position; S8: The main cylinder flange press fitting assembly is lifted out through the longitudinal gap between the main cylinder body 1-21 and the main cylinder plunger 1-24, the main cylinder press sleeve 1-23 is replaced, and then lifted in; S9: The components on the main cylinder body 1-21 are installed in reverse order according to the above steps. The above steps address the shortcomings of the existing technology and propose an improved technical solution. The beneficial effects of the method of the present invention are as follows: 1. When replacing the main cylinder pressure sleeve of the hydraulic press, the main cylinder body of the hydraulic press is disassembled from top to bottom, the main cylinder flange pressure sleeve assembly is lifted out for replacement, and the main cylinder flange pressure sleeve assembly with the replaced main cylinder pressure sleeve is reinstalled in the center of the hydraulic press. Installation is carried out from bottom to top along the pressing center line of the hydraulic press, which improves the efficiency of main cylinder pressure sleeve replacement, reduces damage to other parts during the replacement of the cylinder guide sleeve, increases the safe service life of the hydraulic press, saves replacement costs, ensures installation accuracy, and provides an operational standard for the replacement of the main cylinder pressure sleeve of the hydraulic press. 2. The lifting cylinder adopts a long-stroke hydraulic cylinder, which lifts and lowers in one step without the need for an additional transition lifting rod. The up-and-down movement speed of the main cylinder body is controllable, and the resistance during operation is low. The piston head of the lifting cylinder is equipped with a pad to protect the piston rod head from deformation and damage caused by abnormal external forces. 3. The main cylinder bushing is assembled using a cryogenic pressing method, assisted by a pressing fixture. The pressing process is quick and convenient. An arc groove is provided below the pressing plate of the pressing fixture for easy positioning of the main cylinder bushing during pressing. A nylon positioning block is embedded in the arc groove at the contact point with the main cylinder bushing to prevent indentations on the pressing surface when the main cylinder bushing is pressed into the main cylinder flange. The online replacement method for the main cylinder bushing of a large hydraulic press described in this invention is simple in procedure. It adopts an online replacement method, improving the efficiency of main cylinder bushing replacement and reducing damage to other components during the replacement process.

[0039] In step S2, the T-screw 1-6 of the connecting block 1-5 between the main cylinder body 1-21 and the lifting cylinder 1-4 is removed: the two Haval protective rings at the bottom of the connecting block 1-5 are removed; the T-screw nut at the top of the connecting block 1-5 is removed; the lifting cylinder 1-4 falls back, exposing the spherical pad, and the T-screw 1-6 is pulled out; the lifting cylinder 1-4 rises back to the top position, and the main cylinder 1-2 is locked. The above steps further restrict step S2 to reliably achieve the removal of the T-screw 1-6 of the connecting block 1-5. After removal, the lifting cylinder 1-4 rises back to the top position, locking the main cylinder 1-2.

[0040] In step S5, when lifting cylinder 2-1 lifts the main cylinder body 1-21: open the valve on the valve block of lifting cylinder 2-1 in the hydraulic station, the pump starts loading, and lifting cylinder 2-1 slowly rises. When the top cap 2-2 above the piston rod reaches the lower surface of the main cylinder body 1-21, lift cylinder 2-1 rises further to lift the main cylinder body 1-21; close the valve on the valve block of lifting cylinder 2-1 in the hydraulic station, and observe whether the main cylinder body 1-21 slips down. If so, check the hydraulic circuit and eliminate the source of the fault; when the main cylinder body 1-21 remains stable, stop the pump. The above steps further limit step S5 to reliably achieve lifting cylinder 2-1 lifting the main cylinder body 1-21.

[0041] In step S7, when the main cylinder body 1-21 descends to the set working position along with the lifting cylinder 2-1: place a support frame 3 below the main cylinder body 1-21, the height of the support frame 3 being the set height of the main cylinder 1-21's descent position; after the connecting block 1-5 is removed, oil enters the rodless chamber of the lifting cylinder 2-1. First, open the throttle valve on the valve block of the lifting cylinder 2-1, loosening it one turn, and observe whether the main cylinder body 1-21 descends. If the main cylinder body 1-21 does not descend, then open the main return valve on the valve block. First, loosen the oil throttle valve by one turn and observe whether the main cylinder body 1-21 descends. If the main cylinder body 1-21 does not descend, open the main return oil safety relief valve on the valve block until the main cylinder body 1-21 descends slowly. Adjust the opening of each valve appropriately based on the descent speed of the main cylinder body 1-21. When the lower plane of the main cylinder body 1-21 descends onto the support frame 3, oil enters the rod chamber of the lifting cylinder 2-1, driving the piston rod of the lifting cylinder 2-1 back to the zero position, then stopping the pump and cutting off power. The above steps further limit step S7 to ensure reliable control and operation of the main cylinder body 1-21 descending to the set working position with the lifting cylinder 2-1.

[0042] Step S8, during the disassembly and assembly of the main cylinder pressure sleeve 1-23: The main cylinder flange pressure sleeve assembly is lifted to the designated position through the longitudinal clearance between the main cylinder body 1-21 and the main cylinder plunger 1-24, and the main cylinder pressure sleeve 1-23 is removed; the mating surfaces of the main cylinder flange 1-22 and the main cylinder pressure sleeve 1-23 are machined to the design tolerance accuracy; the main cylinder pressure sleeve 1-23 is machined according to the tolerance accuracy requirements of the main cylinder flange 1-22 and the main cylinder pressure sleeve 1-23; the main cylinder pressure sleeve 1-23 is assembled using a cryogenic press-fit method, with liquid nitrogen cooling of the main cylinder pressure sleeve assisted by press-fitting fixtures. (See attached...) Figure 4 Appendix Figure 5 As shown, the press-fit fixture 4 includes a support plate 4-1, an adjusting screw 4-2, a pressure plate 4-3, and an adjusting nut 4-4. The pressure plate 4-3 is connected to the upper part of the main cylinder pressure sleeve 1-23, and the pressure plate 4-3 is also connected to the lower end of the adjusting nut 4-4. Threaded holes are machined at both ends of the support plate 4-1, and these threaded holes are connected to the lower part of the adjusting screw 4-2. The above steps further limit step S5 to achieve the disassembly and assembly of the main cylinder pressure sleeve 1-23, which requires the use of the press-fit fixture.

[0043] During the press-fitting process using the press-fitting fixture 4, the main cylinder flange 1-22 is first placed on the support plate 4-1 of the press-fitting fixture 4. The adjusting screw 4-2 is connected to the support plate 4-1. During this process, the main cylinder sleeve 1-23 is cooled to the set assembly process dimensions using liquid nitrogen. Then, the main cylinder sleeve 1-23 is hoisted onto the mating surface with the main cylinder flange 1-22. The pressure plate 4-3 is hoisted onto the upper surface of the main cylinder sleeve 1-23. The adjusting screw 4-2 passes through the through holes at both ends of the pressure plate 4-3. By rotating the adjusting nut 4-4, the pressure plate 4-3 is driven downward, causing the main cylinder sleeve 1-23 to be pressed into the main cylinder flange, thus preventing indentations from forming on the pressing surface of the guide sleeve 1-16 during press-fitting. The above structure further limits the steps of using the press-fitting fixture 4, ensuring that the main cylinder sleeve 1-23 is pressed into the main cylinder flange during press-fitting and preventing indentations from forming on the pressing surface of the guide sleeve 1-16 during press-fitting.

[0044] The press plate 4-3 of the press fitting fixture has concave positioning blocks 4-5 at both ends where it contacts the guide sleeve 1-16. The positioning blocks 4-5 sit on the main cylinder press sleeve 1-23. With the above structure, the concave positioning blocks 4-5 provide reliable positioning when the main cylinder press sleeve 1-23 is assembled.

[0045] The positioning block 4-5 is made of nylon, copper, rubber, or plastic. With this structure, the positioning block 4-5 will not damage the contact surface of the master cylinder pressure sleeve 1-23 during use.

[0046] The lifting cylinder 2-1 raises the main cylinder body 1-21 by 45mm-55mm. The lifting height varies depending on the product model, and this is a defined range.

[0047] This invention also relates to a main cylinder structure for a large hydraulic press, comprising a lower beam 1-1, a main cylinder 1-2, an upper beam 1-3, a lifting cylinder 1-4, a connecting block 1-5, a T-screw 1-6, a lifting cylinder 2-1, and a support frame 3. The main cylinder 1-2 includes a main cylinder body 1-21, a main cylinder flange 1-22, a main cylinder pressure sleeve 1-23, and a main cylinder plunger 1-24. The replacement method of this invention is specifically designed for the above-mentioned main cylinder structure of a large hydraulic press, effectively ensuring the replacement result and protecting the product.

[0048] This invention also relates to a press-fitting fixture for the main cylinder sleeve of a large hydraulic press. The press-fitting fixture 4 includes a support plate 4-1, an adjusting screw 4-2, a pressure plate 4-3, and an adjusting nut 4-4. The pressure plate 4-3 is connected to the upper part of the main cylinder sleeve 1-23 and is also connected to the lower end of the adjusting nut 4-4. Threaded holes are machined at both ends of the support plate 4-1, and these threaded holes are connected to the lower part of the adjusting screw 4-2. With the above structure, the press-fitting fixture ensures reliable press-fitting of the main cylinder sleeve 1-23.

[0049] The innovations of this invention regarding the online replacement method for the main cylinder sleeve of a large hydraulic press are as follows: 1. The online replacement method improves the efficiency of main cylinder sleeve replacement, reduces damage to other components during the replacement process, and provides operational guidelines for the replacement of the main cylinder sleeve. 2. The lifting cylinder uses a long-stroke hydraulic cylinder, allowing for controllable up-and-down movement speed of the main cylinder body. It also features low resistance during operation. A pad is provided at the piston head of the lifting cylinder to protect the piston rod head from deformation and damage caused by abnormal external forces. 3. The main cylinder sleeve is assembled using a cryogenic pressing method. Liquid nitrogen cooling is used to assist in the assembly of the main cylinder sleeve using a pressing fixture. This method is simple and convenient. Nylon pressure blocks are embedded at both ends of the pressing plate of the pressing fixture where it contacts the main cylinder sleeve, preventing indentations from forming on the pressing surface when the main cylinder sleeve is pressed into the main cylinder flange.

[0050] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A method for online replacement of the main cylinder bushing of a large hydraulic press, characterized in that: The main cylinder structure of a large hydraulic press includes a lower beam (1-1), a main cylinder (1-2), an upper beam (1-3), a lifting cylinder (1-4), a connecting block (1-5), a T-screw (1-6), a lifting cylinder (2-1), and a support frame (3). The main cylinder (1-2) includes a main cylinder body (1-21), a main cylinder flange (1-22), a main cylinder pressure sleeve (1-23), and a main cylinder plunger (1-24). The replacement steps of the online replacement method for the main cylinder bushing of the large hydraulic press are as follows: S1. The main cylinder body (1-21) is lowered to the working position, and the upper mold device and lower mold device are removed; S2: Lock the main cylinder body (1-21) to the highest position, and remove the T-screw (1-6) of the connecting block (1-5) between the main cylinder body (1-21) and the lifting cylinder (1-4). S3: The lifting cylinder (2-1) falls into the process hole of the lower beam (1-1) of the hydraulic press; S4: The master cylinder (1-2) is unlocked, the lifting cylinder (1-4) falls back to the lowest position along with the master cylinder body (1-21), and the pump stops; S5: The lifting cylinder (2-1) rises and lifts the main cylinder body (1-21); S6: Remove the main cylinder flange press assembly, the connecting block (1-5) between the main cylinder body (1-21) and the lifting cylinder (1-4), and hang the main cylinder flange press assembly on the upper beam 1-3 of the hydraulic press by hand chain hoist; S7: The main cylinder body (1-21) descends to the set working position along with the lifting cylinder (2-1) and lands on the steel support frame (3). The lifting cylinder continues to descend to the lowest position. S8: The main cylinder flange press sleeve assembly is lifted out through the longitudinal clearance between the main cylinder body (1-21) and the main cylinder plunger (1-24), and the main cylinder press sleeve (1-23) is replaced and then lifted in; S9: Install the components on the main cylinder block (1-21) in reverse order according to the steps above.

2. The method for online replacement of the main cylinder bushing of a large hydraulic press according to claim 1, characterized in that: In step S2, remove the T-screw (1-6) of the connecting block (1-5) between the main cylinder body (1-21) and the lifting cylinder (1-4): remove the two Haval protective rings at the bottom of the connecting block (1-5); remove the T-screw nut at the top of the connecting block (1-5); the lifting cylinder (1-4) falls back, exposing the spherical pad, and the T-screw (1-6) is pulled out; the lifting cylinder (1-4) rises back to the lifting position, and the main cylinder (1-2) is locked.

3. The method for online replacement of the main cylinder bushing of a large hydraulic press according to claim 1 or 2, characterized in that: In step S5, when the lifting cylinder (2-1) lifts the main cylinder body (1-21): open the valve on the valve block of the lifting cylinder (2-1) of the hydraulic station, the pump starts to load, and the lifting cylinder (2-1) slowly rises. When the top cap (2-2) above the piston rod reaches the lower surface of the main cylinder body (1-21), the lifting cylinder (2-1) is raised again to lift the main cylinder body (1-21); close the valve on the valve block of the lifting cylinder (2-1) of the hydraulic station, and observe whether the main cylinder body (1-21) is slipping down. If so, check the hydraulic circuit and eliminate the source of the fault; when the main cylinder body (1-21) remains stable, stop the pump.

4. The method for online replacement of the main cylinder bushing of a large hydraulic press according to claim 1 or 2, characterized in that: In step S7, when the main cylinder body (1-21) descends to the set working position along with the lifting cylinder (2-1): a support frame (3) is placed below the main cylinder body (1-21), and the height of the support frame (3) is the set height of the main cylinder (1-2) descent position; after the connecting block (1-5) is removed, oil enters the rodless chamber of the lifting cylinder (2-1), first open the throttle valve of the control cylinder on the valve block of the lifting cylinder (2-1), loosen it one turn, and observe whether the main cylinder body (1-21) descends. If the main cylinder body (1-21) does not descend, then open the valve block. Loosen the main return oil throttle valve by one turn and observe whether the main cylinder body (1-21) descends. If the main cylinder body (1-21) does not descend, open the main return oil safety relief valve on the valve block until the main cylinder body (1-21) descends slowly. Adjust the opening of each valve appropriately according to the descent speed of the main cylinder body (1-21). When the lower plane of the main cylinder body (1-21) descends and falls onto the support frame (3), oil enters the rod chamber of the lifting cylinder (2-1), driving the piston rod of the lifting cylinder (2-1) back to the zero position, and then the pump stops and the power is cut off.

5. The method for online replacement of the main cylinder bushing of a large hydraulic press according to claim 1 or 2, characterized in that: In step S8, when disassembling and assembling the master cylinder bushing (1-23): The master cylinder flange bushing assembly is lifted to a designated position through the longitudinal clearance between the master cylinder body (1-21) and the master cylinder plunger (1-24), and the master cylinder bushing (1-23) is removed; the mating surfaces of the master cylinder flange (1-22) and the master cylinder bushing (1-23) are machined to the design tolerance requirements; the master cylinder bushing (1-23) is machined according to the tolerance requirements of the master cylinder flange (1-22) and the master cylinder bushing (1-23); the master cylinder bushing (1-23) is then... 1-23) The main cylinder sleeve is assembled by cryogenic pressing. The main cylinder sleeve is cooled by liquid nitrogen and assembled with pressing tooling. The pressing tooling (4) includes a support plate (4-1), an adjusting screw (4-2), a pressure plate (4-3), and an adjusting nut (4-4). The pressure plate (4-3) is connected to the upper part of the main cylinder sleeve (1-23). ​​The pressure plate (4-3) is also connected to the lower end of the adjusting nut (4-4). The support plate (4-1) has threaded holes at both ends, and the threaded holes are connected to the lower part of the adjusting screw (4-2).

6. The method for online replacement of the main cylinder bushing of a large hydraulic press according to claim 5, characterized in that: When the press-fitting fixture (4) is press-fitting, the main cylinder flange (1-22) is first placed on the support plate (4-1) of the press-fitting fixture (4), and the adjusting screw (4-2) is connected to the support plate (4-1). During this period, the main cylinder press sleeve (1-23) is cooled to the set assembly process size with liquid nitrogen. Then the main cylinder press sleeve (1-23) is hoisted to the mating surface with the main cylinder flange (1-22), and the pressure plate (4-3) is hoisted to the upper surface of the main cylinder press sleeve (1-23). ​​The adjusting screw (4-2) passes through the through holes at both ends of the pressure plate (4-3). By rotating the adjusting nut (4-4), the pressure plate (4-3) is driven to move downward, thereby driving the main cylinder press sleeve (1-23) to be squeezed into the main cylinder flange, so as to prevent the press-fitting surface of the guide sleeve (1-16) from producing indentations during the press-fitting.

7. The method for online replacement of the main cylinder bushing of a large hydraulic press according to claim 6, characterized in that: The pressure plate (4-3) of the press fitting fixture has concave positioning blocks (4-5) at both ends of its contact portion with the guide sleeve (1-16), and the positioning blocks (4-5) sit on the main cylinder pressure sleeve (1-23).

8. The method for online replacement of the main cylinder bushing of a large hydraulic press according to claim 7, characterized in that: The positioning blocks (4-5) are made of nylon, copper, rubber, or plastic.

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