A three-stage pressurizing continuous pre-pressing machine and gradient pressurizing method

Abstract

The present invention belongs to the technical field of pre-pressing machines, and discloses a three-stage pressurizing continuous pre-pressing machine and a gradient pressurizing method, including a frame, a workbench is fixedly installed on the inner side surface of the frame near the bottom end, a three-way valve is fixedly installed in the middle of the top end of the frame, the front and rear ends of the three-way valve are fixedly connected with air pipes, the top end of the three-way valve is connected to an external oil pump, and the inner side surface of the frame is provided with a first press plate located above the workbench. The present invention sets a pressurizing component, and sets a second pressurizing pipe and a third pressurizing pipe inside the first pressurizing pipe, and realizes multiple pressurizing processes through the flow of hydraulic oil and the coordination between the first press plate, the second press plate, and the third press plate. The whole process can be completed by the same set of devices, and there is no need to transfer the plastic plate between different presses, so that it can be pressurized multiple times under the same set of processes to meet different pre-pressing requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of pre-pressing machines, and in particular relates to a three-stage pressurizing continuous pre-pressing machine and a gradient pressurizing method. Background Art

[0002] The pre-press is an auxiliary machine of the plywood production line and an important equipment in the plastic processing industry. In plywood production, the pre-press is mainly used to shorten the hot pressing cycle and improve the quality of the board. It performs a short period of cold pressing on the veneer after the glue coating and assembly to make it initially formed, and then sends it to the hot press for hot pressing and gluing. In plastic processing, the pre-press is used to increase the density of plastic materials, stabilize the size and improve the quality.

[0003] Conventional pre-pressing machines are mainly mechanical hydraulic presses, which mainly include a fixed workbench, a movable pressing plate and a hydraulic cylinder on the top. When in use, the pre-pressing operation is achieved by placing the plastic plate on the workbench and driving the pressing plate downward by turning on the hydraulic cylinder. This pre-pressing method can only achieve the application of one type of pressure. When different pressures need to be applied, different presses need to be used in combination, and the convenience of use is poor.

[0004] At the same time, the pre-pressing machine currently used can only provide a linear pressure application method when applying pressure, and cannot provide a gradient pressurization method. When facing some special plastic plates, it is impossible to achieve an effective pressurization process, and repeated pressure is required to complete the pre-pressing process, which is in urgent need of improvement. Summary of the invention

[0005] The object of the present invention is to provide a three-stage pressurizing continuous pre-pressing machine and a gradient pressurizing method to solve the problems raised in the above-mentioned background technology.

[0006] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions: a three-stage pressurizing continuous pre-pressing machine, comprising a frame, a workbench is fixedly installed on the inner side surface of the frame near the bottom end, a three-way valve is fixedly installed in the middle of the top end of the frame, the front and rear ends of the three-way valve are fixedly connected with air delivery pipes, the top end of the three-way valve is connected with an external oil pump, the inner side surface of the frame is provided with a first pressing plate located above the workbench, the first pressing plate is internally movably sleeved with a second pressing plate, the second pressing plate is internally movably sleeved with a third pressing plate, the second pressing plate is displaced up and down relative to the first pressing plate, the third pressing plate is displaced up and down relative to the second pressing plate, the left and right sides of the top end of the first pressing plate and the left and right sides of the top end of the second pressing plate and the left and right sides of the top end of the third pressing plate are fixedly installed with extension rods, the top end of the extension rod located at the top end of the first pressing plate is fixedly installed with a first locking frame, the top end of the extension rod located at the top end of the second pressing plate is fixedly installed with a second locking frame, the top end of the third pressing plate located at the top end of the third pressing plate is fixedly installed with a third locking frame, and the front and rear sides of the inner side surface of the frame are fixedly sleeved with pressurizing components.

[0007] Before pressurizing the plastic plate, the plastic plate can be placed directly above the workbench, and the top of the three-way valve is connected to the external oil pump, and the pressurizing component is restored to the initial state to complete the preparation before pressurizing the plastic plate.

[0008] As a further technical solution of the present invention, the bottom cross-sectional areas of the first pressing plate, the second pressing plate and the third pressing plate are the same, and the first locking frame, the second locking frame and the third locking frame are respectively connected to the pressurizing components.

[0009] In the initial state, the top ends of the first pressing plate, the second pressing plate and the third pressing plate are all on the same horizontal plane, and the bottom end of the first locking frame contacts the top end of the second locking frame, and the bottom end of the second locking frame contacts the top end of the third locking frame. At this time, the device is in a preliminary pre-pressing state.

[0010] As a further technical solution of the present invention, the pressurizing assembly includes a first pressurizing tube, which is fixedly sleeved on the frame, a first piston plate is movably sleeved inside the first pressurizing tube, a second pressurizing tube is fixedly connected to the bottom end of the first piston plate, and the top end of the first pressurizing tube is fixedly connected to the bottom end of the gas pipe.

[0011] As a further technical solution of the present invention, the bottom end of the second pressurized tube passes through the bottom end of the first pressurized tube and is fixedly connected to the first pressure plate, the second pressurized tube is internally movably sleeved with a second piston plate, the bottom end of the second piston plate is fixedly connected to a third pressurized tube, and the bottom end of the third pressurized tube passes through the bottom end of the first pressure plate and is fixedly connected to the second pressure plate.

[0012] As a further technical solution of the present invention, the third pressurized tube is internally movably sleeved with a third piston plate, the bottom end of the third piston plate is fixedly connected with a third pressure plate, and the bottom end of the third pressure plate passes through the bottom end of the second pressure plate.

[0013] As a further technical solution of the present invention, the outer side surfaces of the first pressure plate, the second pressure plate and the third pressure plate are connected to the first locking frame, the second locking frame and the third locking frame respectively.

[0014] As a further technical solution of the present invention, the front and rear sides of the first pressurized pipe near the bottom are fixedly connected with the first delivery pipe, the left and right sides of the third pressurized pipe near the bottom are fixedly connected with the second delivery pipe, a three-way valve is fixedly connected between the first delivery pipe and the second delivery pipe, and the inner side of the three-way valve is connected to the second pressurized pipe.

[0015] When performing preliminary pre-pressurization, the external oil pump can be turned on. At this time, the hydraulic oil can be output into the interior of the three-way valve, and enter the interior of the first pressure pipe through the air pipes at the left and right ends of the three-way valve, and pressure is applied to the first piston plate. At this time, the first piston plate and the second pressure pipe are displaced downward accordingly, and the first pressure plate at the bottom is synchronously driven to displace synchronously. At this time, the spacing between the first pressure plate, the second pressure plate, and the third pressure plate remains unchanged. When the first pressure plate is displaced downward, the first locking frame can be synchronously driven to displace downward. At this time, the first pressure plate at the bottom is moved downward accordingly, and the second pressure plate and the third pressure plate at the bottom are synchronously driven The three pressure plates move synchronously until the bottom end of the third pressure plate contacts the plastic plate to complete the initial pressurization process. At this time, the downward pressure height of the first pressure plate can be kept unchanged, and the valve of the first delivery pipe is opened, and the valve of the three-way valve located on the side of the second pressurized pipe is opened at the same time. At this time, the hydraulic oil shredder enters the interior of the second pressurized pipe and applies pressure to the second piston plate at the same time, and drives the third pressurized pipe and the second pressure plate to move downward, and drives the second locking frame to move downward. At this time, the second pressure plate and the third pressure plate can move downward relative to the first pressure plate, and the plastic plate is pressurized for the second time to complete multiple pressurization processes.

[0016] By setting up a pressurizing component, and arranging a second pressurizing pipe and a third pressurizing pipe inside the first pressurizing pipe, multiple pressurizing processes are realized through the flow of hydraulic oil and the cooperation between the first pressure plate, the second pressure plate, and the third pressure plate. The entire process can be completed by the same set of devices, and there is no need to transfer the plastic plate between different presses, so that it can be pressurized multiple times in the same set of processes to meet different pre-pressing requirements.

[0017] At the same time, after the secondary pressurization is completed, the valve at the bottom of the three-way valve can be opened. At this time, the hydraulic oil enters the interior of the third pressurizing pipe through the second delivery pipe, and at the same time, downward pressure is applied to the third piston plate. At this time, the third pressure plate moves downward and synchronously drives the third locking frame to move downward. At this time, the third pressure plate at the bottom moves downward relative to the second pressure plate, further pressurizing the plastic plate, completing three pressurizations and completing the gradient pressurization process.

[0018] By utilizing the multi-stage pressurizing process of the pressurizing component and coordinating the relative displacement process of the first press plate, the second press plate, and the third press plate, the device can complete multiple different pressurizing processes, and the pressure in the entire pressurizing process increases in a gradient, that is, while maintaining the original pressure, multiple pressurizations are performed, so that the device can meet the pre-pressing requirements of special plastic plates, avoid the problem of traditional devices requiring multiple and repeated pressurizations, and improve the pre-pressing efficiency.

[0019] A gradient pressurizing method for a three-stage pressurizing continuous pre-pressing machine comprises the following steps:

[0020] S1: When pressurizing, first place the plastic plate on the top of the workbench and turn on the oil pump outside the three-way valve. At this time, the hydraulic oil can be output to the inside of the three-way valve and enter the inside of the first pressurizing pipe through the air pipe, and apply pressure to the first piston plate. At this time, the second pressurizing pipe and the first pressure plate move downward, and synchronously drive the first locking frame to move downward, and at the same time drive the first pressure plate, the second pressure plate, and the third pressure plate at the bottom to move downward synchronously, and the plastic plate on the top of the workbench is initially pressurized through the third pressure plate;

[0021] S2: After the initial pressurization is completed, the valve inside the first delivery pipe can be opened, and at the same time, the valve on the side of the three-way valve close to the second pressurized pipe is opened and the valve at the bottom of the three-way valve is closed. At this time, the hydraulic oil enters the second pressurized pipe and pushes the second piston plate and the second pressure plate to move downward, until the second pressure plate is driven to move downward relative to the first pressure plate, completing the secondary pressurization process;

[0022] S3: After completing the secondary pressurization, the valve at the bottom of the three-way valve can be opened. At this time, the hydraulic oil will enter the interior of the third pressurizing pipe, and drive the third piston plate and the third pressure plate to move downward, and finally drive the third pressure plate to move downward relative to the second pressure plate, completing the gradient pressurization process.

[0023] The beneficial effects of the present invention are as follows:

[0024] (1) The present invention sets a pressurizing component, and sets a second pressurizing pipe and a third pressurizing pipe inside the first pressurizing pipe. Through the flow of hydraulic oil and the coordination between the first pressure plate, the second pressure plate and the third pressure plate, multiple pressurizing processes are realized. The whole process can be completed by the same set of devices, and there is no need to transfer the plastic plate between different presses, so that it can be pressurized multiple times in the same set of processes to meet different pre-pressing requirements.

[0025] (2) The present invention utilizes a multi-stage pressurizing process of the pressurizing component and cooperates with the relative displacement process of the first pressure plate, the second pressure plate, and the third pressure plate, so that the device can complete multiple different pressurizing processes, and the pressure in the entire pressurizing process increases in a gradient, that is, while maintaining the original pressure, multiple pressurizations are performed, so that the device can meet the pre-pressing requirements of special plastic plates, avoid the problem of traditional devices requiring multiple and repeated pressurizations, and improve the pre-pressing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 It is a schematic diagram of the coordination of the frame and the workbench structure of the present invention;

[0028] Figure 3 It is a schematic diagram of the coordination of the first pressing plate, the second pressing plate and the third pressing plate structure of the present invention;

[0029] Figure 4 It is a cross-sectional schematic diagram of the internal structure of the first pressing plate, the second pressing plate and the third pressing plate of the present invention;

[0030] Figure 5 It is an exploded schematic diagram of the first pressing plate, the second pressing plate and the third pressing plate structure of the present invention;

[0031] Figure 6 It is a separate schematic diagram of the pressurizing assembly structure of the present invention;

[0032] Figure 7 It is a cross-sectional schematic diagram of the internal structure of the pressurizing component of the present invention.

[0033] In the figure: 1. frame; 2. workbench; 3. three-way valve; 4. gas delivery pipe; 5. first pressure plate; 6. second pressure plate; 7. third pressure plate; 8. extension rod; 9. first locking frame; 10. second locking frame; 11. third locking frame; 12. pressurizing assembly; 121. first pressurizing pipe; 122. first piston plate; 123. second pressurizing pipe; 124. second piston plate; 125. third pressurizing pipe; 126. third piston plate; 127. first pressure plate; 128. second pressure plate; 129. third pressure plate; 1210. first delivery pipe; 1211. second delivery pipe; 1212. three-way valve. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] like Figures 1 to 7 As shown, in the embodiment of the present invention, a three-stage pressurized continuous pre-pressing machine includes a frame 1, a workbench 2 is fixedly installed on the inner side surface of the frame 1 near the bottom end, a three-way valve 3 is fixedly installed in the middle of the top end of the frame 1, and the front and rear ends of the three-way valve 3 are fixedly connected with an air delivery pipe 4, and the top of the three-way valve 3 is connected to an external oil pump. The inner side surface of the frame 1 is provided with a first pressing plate 5 located above the workbench 2, and the first pressing plate 5 is internally movably sleeved with a second pressing plate 6, and the second pressing plate 6 is internally movably sleeved with a third pressing plate 7, and the second pressing plate 6 is relative to the first pressing plate 5. The third pressing plate 7 moves up and down relative to the second pressing plate 6, and the left and right sides of the top of the first pressing plate 5, the left and right sides of the top of the second pressing plate 6, and the left and right sides of the top of the third pressing plate 7 are fixedly installed with extension rods 8, the top of the extension rod 8 located at the top of the first pressing plate 5 is fixedly installed with a first locking frame 9, the top of the extension rod 8 located at the top of the second pressing plate 6 is fixedly installed with a second locking frame 10, and the top of the third pressing plate 7 located at the top of the third pressing plate 7 is fixedly installed with a third locking frame 11, and the front and rear sides of the inner side of the frame 1 are fixedly sleeved with a pressurizing assembly 12.

[0036] Before pressurizing the plastic plate, the plastic plate can be placed directly above the workbench 2, and the top of the three-way valve 3 is connected to the external oil pump, and the pressurizing component 12 is restored to its initial state to complete the preparation before pressurizing the plastic plate.

[0037] like Figure 3 and Figure 4 as well as Figure 5 As shown, the bottom cross-sectional areas of the first pressing plate 5, the second pressing plate 6 and the third pressing plate 7 are the same, and the first locking frame 9, the second locking frame 10 and the third locking frame 11 are respectively connected to the pressurizing assembly 12.

[0038] In the initial state, the top ends of the first pressure plate 5, the second pressure plate 6, and the third pressure plate 7 are all on the same horizontal plane, and the bottom end of the first locking frame 9 is in contact with the top end of the second locking frame 10, and the bottom end of the second locking frame 10 is in contact with the top end of the third locking frame 11. At this time, the device is in a preliminary pre-compression state.

[0039] like Figure 1 and Figure 6 and Figure 7 As shown, the pressurizing assembly 12 includes a first pressurizing tube 121, which is fixedly sleeved with the frame 1, and the first pressurizing tube 121 is internally movably sleeved with a first piston plate 122, and the bottom end of the first piston plate 122 is fixedly connected with a second pressurizing tube 123, the top of the first pressurizing tube 121 is fixedly connected with the bottom end of the gas pipe 4, the bottom end of the second pressurizing tube 123 passes through the bottom end of the first pressurizing tube 121 and is fixedly connected with a first pressure plate 127, the second pressurizing tube 123 is internally movably sleeved with a second piston plate 124, and the bottom end of the second piston plate 124 is fixedly connected with a third pressurizing tube 125, the bottom end of the third pressurizing tube 125 passes through the bottom end of the first pressure plate 127 and is fixedly connected with a second pressure plate 128, and the inside of the third pressurizing tube 125 A third piston plate 126 is movably sleeved, and the bottom end of the third piston plate 126 is fixedly connected to a third pressure plate 129, and the bottom end of the third pressure plate 129 passes through the bottom end of the second pressure plate 128. The outer sides of the first pressure plate 127, the second pressure plate 128 and the third pressure plate 129 are respectively connected to the first locking frame 9, the second locking frame 10 and the third locking frame 11, the front and rear sides of the first pressurizing pipe 121 near the bottom are fixedly connected to the first delivery pipe 1210, and the left and right sides of the third pressurizing pipe 125 near the bottom are fixedly connected to the second delivery pipe 1211, a three-way valve 1212 is fixedly connected between the first delivery pipe 1210 and the second delivery pipe 1211, and the inner side of the three-way valve 1212 is connected to the second pressurizing pipe 123.

[0040] Embodiment: When performing preliminary pre-pressurization, the external oil pump can be turned on, and the hydraulic oil can be output into the interior of the three-way valve 3, and enter the interior of the first pressurizing pipe 121 through the air supply pipes 4 at the left and right ends of the three-way valve 3, and pressure is applied to the first piston plate 122. At this time, the first piston plate 122 and the second pressurizing pipe 123 are displaced downward accordingly, and the first pressure plate 127 at the bottom is synchronously driven to displace synchronously. At this time, the spacing between the first pressure plate 5, the second pressure plate 6, and the third pressure plate 7 remains unchanged. When the first pressure plate 127 is displaced downward, the first locking frame 9 can be synchronously driven to displace downward. At this time, the first pressure plate 5 at the bottom is moved downward accordingly, and the second pressure plate 6 and the third pressure plate 7 at the bottom are synchronously driven. The three pressure plates 7 are displaced synchronously until the bottom end of the third pressure plate 7 contacts the plastic plate, completing the initial pressurization process. At this time, the downward pressure height of the first pressure plate 5 can be kept unchanged, and the valve of the first delivery pipe 1210 is opened, and the valve of the three-way valve 1212 located on the side of the second pressurizing pipe 123 is opened at the same time. At this time, the hydraulic oil shredder enters the interior of the second pressurizing pipe 123, and at the same time applies pressure to the second piston plate 124, and drives the third pressurizing pipe 125 and the second pressure plate 128 to move downward, and drives the second locking frame 10 to move downward. At this time, the second pressure plate 6 and the third pressure plate 7 can be displaced downward relative to the first pressure plate 5, and the plastic plate is pressurized for the second time to complete multiple pressurization processes.

[0041] By setting up a pressurizing component 12, and arranging a second pressurizing pipe 123 and a third pressurizing pipe 125 inside the first pressurizing pipe 121, multiple pressurizing processes are realized through the flow of hydraulic oil and the cooperation between the first pressure plate 5, the second pressure plate 6, and the third pressure plate 7. The whole process can be completed by the same set of equipment, and there is no need to transfer the plastic plate between different presses, so that it can be pressurized multiple times in the same set of processes to meet different pre-pressing requirements.

[0042] Embodiment: At the same time, when the secondary pressurization is completed, the valve at the bottom end of the three-way valve 1212 can be opened. At this time, the hydraulic oil enters the interior of the third pressurizing pipe 125 through the second delivery pipe 1211, and at the same time, downward pressure is applied to the third piston plate 126. At this time, the third pressure plate 129 moves downward and synchronously drives the third locking frame 11 to move downward. At this time, the third pressure plate 7 at the bottom moves downward relative to the second pressure plate 6, further pressurizing the plastic plate, completing three pressurizations and completing the gradient pressurization process.

[0043] By utilizing the multi-stage pressurizing process of the pressurizing component 12 and coordinating the relative displacement process of the first press plate 5, the second press plate 6, and the third press plate 7, the device can complete multiple different pressurizing processes, and the pressure in the entire pressurizing process increases in a gradient, that is, while maintaining the original pressure, multiple pressurizations are performed, so that the device can meet the pre-pressing requirements of special plastic plates, avoid the problem of traditional devices requiring multiple and repeated pressurizations, and improve the pre-pressing efficiency.

[0044] A gradient pressurizing method for a three-stage pressurizing continuous pre-pressing machine comprises the following steps:

[0045] S1: When pressurizing, the plastic plate can be placed above the workbench 2 first, and the oil pump outside the three-way valve 3 can be turned on. At this time, the hydraulic oil can be output to the inside of the three-way valve 3, and enter the inside of the first pressurizing pipe 121 through the air pipe 4, and apply pressure to the first piston plate 122. At this time, the second pressurizing pipe 123 and the first pressure plate 127 move downward accordingly, synchronously driving the first locking frame 9 to move downward, and at the same time driving the first pressure plate 5, the second pressure plate 6, and the third pressure plate 7 at the bottom to move downward synchronously, and the plastic plate on the top of the workbench 2 is initially pressurized through the third pressure plate 7;

[0046] S2: After the initial pressurization is completed, the valve inside the first delivery pipe 1210 can be opened, and at the same time, the valve of the three-way valve 1212 close to the second pressurizing pipe 123 is opened and the valve at the bottom of the three-way valve 1212 is closed. At this time, the hydraulic oil enters the second pressurizing pipe 123 and pushes the second piston plate 124 and the second pressure plate 128 to move downward, until the second pressure plate 6 is driven to move downward relative to the first pressure plate 5, completing the secondary pressurization process;

[0047] S3: After completing the secondary pressurization, the valve at the bottom of the three-way valve 1212 can be opened. At this time, the hydraulic oil enters the interior of the third pressurizing pipe 125, and drives the third piston plate 126 and the third pressure plate 129 to move downward, and finally drives the third pressure plate 7 to move downward relative to the second pressure plate 6, completing the gradient pressurization process.

[0048] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A three-stage continuous pressurizing machine, comprising a frame (1), characterized in that: A workbench (2) is fixedly mounted on a position near the bottom end of the inner side surface of the frame (1); a three-way valve (3) is fixedly mounted in the middle of the top end of the frame (1); both front and rear ends of the three-way valve (3) are fixedly connected to an air delivery pipe (4); the top end of the three-way valve (3) is connected to an external oil pump; a first pressing plate (5) located above the workbench (2) is provided on the inner side surface of the frame (1); a second pressing plate (6) is movably sleeved inside the first pressing plate (5); a third pressing plate (7) is movably sleeved inside the second pressing plate (6); the second pressing plate (6) is displaced up and down relative to the first pressing plate (5); and the third pressing plate (7) is displaced up and down relative to the first pressing plate (5). In response to the up and down displacement of the second pressing plate (6), the left and right sides of the top of the first pressing plate (5), the left and right sides of the top of the second pressing plate (6), and the left and right sides of the top of the third pressing plate (7) are all fixedly installed with extension rods (8); the top of the extension rod (8) located at the top of the first pressing plate (5) is fixedly installed with a first locking frame (9); the top of the extension rod (8) located at the top of the second pressing plate (6) is fixedly installed with a second locking frame (10); the top of the third pressing plate (7) located at the top of the third pressing plate (7) is fixedly installed with a third locking frame (11); and the front and rear sides of the inner side surface of the frame (1) are fixedly sleeved with a pressure assembly (12).

2. A three-stage pressurizing continuous pre-pressing machine according to claim 1, characterized in that: The cross-sectional areas of the bottom ends of the first pressing plate (5), the second pressing plate (6) and the third pressing plate (7) are the same, and the first locking frame (9), the second locking frame (10) and the third locking frame (11) are respectively connected to the pressurizing assembly (12).

3. A three-stage pressurizing continuous pre-pressing machine according to claim 2, characterized in that: The pressurizing assembly (12) comprises a first pressurizing tube (121), the first pressurizing tube (121) is fixedly sleeved with the frame (1), a first piston plate (122) is movably sleeved inside the first pressurizing tube (121), a second pressurizing tube (123) is fixedly connected to the bottom end of the first piston plate (122), and the top end of the first pressurizing tube (121) is fixedly connected to the bottom end of the gas pipe (4).

4. A three-stage pressurizing continuous pre-pressing machine according to claim 3, characterized in that: The bottom end of the second pressurizing tube (123) passes through the bottom end of the first pressurizing tube (121) and is fixedly connected to the first pressure plate (127); the second pressurizing tube (123) is internally movably sleeved with a second piston plate (124); the bottom end of the second piston plate (124) is fixedly connected to a third pressurizing tube (125); the bottom end of the third pressurizing tube (125) passes through the bottom end of the first pressure plate (127) and is fixedly connected to a second pressure plate (128).

5. A three-stage pressurizing continuous pre-pressing machine according to claim 4, characterized in that: The third pressure tube (125) is internally movably sleeved with a third piston plate (126), the bottom end of the third piston plate (126) is fixedly connected with a third pressure plate (129), and the bottom end of the third pressure plate (129) passes through the bottom end of the second pressure plate (128).

6. A three-stage pressurizing continuous pre-pressing machine according to claim 5, characterized in that: The outer sides of the first pressure plate (127), the second pressure plate (128) and the third pressure plate (129) are respectively connected to the first locking frame (9), the second locking frame (10) and the third locking frame (11).

7. A three-stage pressurizing continuous pre-pressing machine according to claim 6, characterized in that: The first pressurizing pipe (121) is fixedly connected to the first delivery pipe (1210) on both the front and rear sides near the bottom end, and the third pressurizing pipe (125) is fixedly connected to the second delivery pipe (1211) on both the left and right sides near the bottom end. A three-way valve (1212) is fixedly connected between the first delivery pipe (1210) and the second delivery pipe (1211), and the inner side surface of the three-way valve (1212) is connected to the second pressurizing pipe (123).

8. The gradient pressurizing method of a three-stage pressurizing continuous pre-pressing machine according to claim 7, characterized in that: The following steps are involved: S1: When pressurizing, the plastic plate can first be placed above the workbench (2), and the oil pump outside the three-way valve (3) can be turned on. At this time, the hydraulic oil can be output to the inside of the three-way valve (3), and enter the inside of the first pressurizing pipe (121) through the air pipe (4), and pressure is applied to the first piston plate (122). At this time, the second pressurizing pipe (123) and the first pressure plate (127) move downward accordingly, synchronously driving the first locking frame (9) to move downward, and at the same time driving the first pressure plate (5), the second pressure plate (6), and the third pressure plate (7) at the bottom to move downward synchronously, and the plastic plate at the top of the workbench (2) is initially pressurized through the third pressure plate (7); S2: After the initial pressurization is completed, the valve inside the first delivery pipe (1210) can be opened, and at the same time, the valve of the three-way valve (1212) close to the second pressurizing pipe (123) is opened and the valve at the bottom end of the three-way valve (1212) is closed. At this time, the hydraulic oil enters the second pressurizing pipe (123) and pushes the second piston plate (124) and the second pressure plate (128) to move downward, until the second pressure plate (6) is driven to move downward relative to the first pressure plate (5), completing the secondary pressurization process; S3: After completing the secondary pressurization, the valve at the bottom of the three-way valve (1212) can be opened. At this time, the hydraulic oil enters the interior of the third pressurizing pipe (125), and drives the third piston plate (126) and the third pressure plate (129) to move downward, and finally drives the third pressure plate (7) to move downward relative to the second pressure plate (6), completing the gradient pressurization process.

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