PVC plate extrusion equipment and working method thereof

Abstract

The invention discloses PVC plate extrusion equipment and a working method thereof, and particularly relates to the technical field of PVC plate processing.The PVC plate extrusion equipment is provided with two sets of die lips, a switching unit and a sealing unit, the states of the two sets of die lips in a die plate are switched according to production requirements, one set of lip plates are in the use state, and the other set of lip plates are stored and hidden in corresponding driving cavities; the die lip does not participate in extrusion work, and the die lip in a closed state is sealed by the sealing plate; in the closed state, the sliding sleeve frame is driven to slide in a limited mode along the cavity through rotation of the threaded rod until the sliding sleeve frame slides to the position of the inclined table, the inclined table and the end face of the movable plate form abutting-pushing contact, and the movable plate slides in the sliding sleeve frame in the vertical direction under pushing of the inclined face, so that the sealing plate leaves the interior of the cavity; high-temperature melt is prevented from permeating into the driving cavity to cause pollution and adhesion; the die lip sets are switched in the non-stop state, rapid switching of different plate specifications is achieved, the die lips in the non-working state are effectively sealed, and melt pollution is prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of PVC plate processing, in particular to a PVC plate extrusion equipment and a working method thereof. BACKGROUND

[0002] Polyvinyl chloride (PVC) plate is widely used in building decoration, advertising signs, home products and industrial parts due to its excellent corrosion resistance, water resistance, processability and economy. Common PVC plates include hard PVC plates, foamed PVC plates (such as snowflake plates), transparent PVC plates, etc. The core equipment is a double-screw or conical double-screw extruder, which is matched with a plate die and a calender to form a plate shape by extruding the PVC material after heating and plasticizing, and then the thickness and surface finish are determined by a three-roll calender, and finally cooled and cut.

[0003] According to the search, the patent with publication number CN111113840B discloses a PVC plate extrusion equipment. One extrusion piston extrudes the material, and the other extrusion cylinder performs feeding operation. The alternating operation ensures uninterrupted extrusion and improves the working efficiency of the extrusion device.

[0004] In the existing scheme, the die and the die lip plate are mainly replaced by manual operation, which leads to low specification switching efficiency, long downtime, large manual error and other problems, and cannot meet the flexible manufacturing requirements of multi-variety continuous production. Once the die lip is contaminated, worn or coked, it needs to be replaced, which seriously affects the production rhythm. SUMMARY

[0005] The present application aims to provide a PVC plate extrusion equipment and a working method thereof to solve the problems mentioned in the background.

[0006] The technical problem solved by the present application is:

[0007] In the existing scheme, the die and the die lip plate are mainly replaced by manual operation, which leads to low specification switching efficiency, long downtime, large manual error and other problems, and cannot meet the flexible manufacturing requirements of multi-variety continuous production. Once the die lip is contaminated, worn or coked, it needs to be replaced, which seriously affects the production rhythm.

[0008] The present application can be achieved by the following technical solutions:

[0009] A PVC plate extrusion equipment, comprising a barrel, a die box for extruding a plate type is communicated with the discharge end of the barrel through a feeding port, a tapered channel is arranged in the interior of the die box and communicated with the feeding port, and a die plate for extrusion is arranged on one side of the tapered channel;

[0010] Two groups of die lips not used at the same time are arranged in the die plate;

[0011] Each group of die lip comprises a driving cavity arranged on the die plate, a lip plate is slidingly arranged in the driving cavity, an end of the lip plate is provided with a pressure roller frame, and a spring is sleeved on one side of the end of the lip plate, and an end of the spring is fixed in the cavity in the driving cavity;

[0012] The die plate is provided with a switching unit for switching the use state of the two groups of die lips;

[0013] The switching unit comprises a driving shaft driven by an internal motor, two cams are sleeved on the outer part of the driving shaft respectively, the angle interval of the two cams is 180 degrees, and the cams are abutted with the corresponding pressure roller frames;

[0014] The die plate is provided with a sealing unit for sealing each driving cavity near the corresponding die lip;

[0015] The sealing unit comprises a cavity, a threaded rod is arranged in the cavity, a sliding sleeve frame is sleeved on the outer part of the threaded rod in a limiting sliding mode in the cavity, a movable plate is slidingly arranged in the sliding sleeve frame, and a sealing plate is arranged on one side of the movable plate;

[0016] The top and bottom of the cavity are provided with inclined tables with the same inclination angle, and the two end faces of the movable plate are abutted with the corresponding inclined tables;

[0017] A piston sleeve is arranged on the outer part of the movable plate, and the piston sleeve is arranged in a limiting sliding mode with the sliding sleeve frame.

[0018] Further technical improvements of the present application are that the die plate comprises a fixed die, a movable die is arranged above the fixed die in a lifting mode, and an extrusion channel is arranged between the fixed die and the movable die.

[0019] Further technical improvements of the present application are that an electric push rod is arranged on the top of the cavity in the die box to push the movable die to move vertically, a flexible sealing gasket is connected to one side of the movable die, and an end of the flexible sealing gasket is fixed to the inner wall of the die box.

[0020] Further technical improvements of the present application are that a compression unit is arranged above the tapered channel;

[0021] The compression unit comprises a stroke air cylinder arranged on the top of the cavity in the die box, a gas bag is arranged on the pushing end of the stroke air cylinder, and the gas bag is in contact with the flexible sealing gasket.

[0022] Further technical improvements of the present application are that a low-pressure exhaust port is arranged on one side of the movable die adjacent to the tapered channel, a ceramic foam plate is arranged on the gas inlet end of the low-pressure exhaust port, and a heat radiation plate is embeddedly arranged on the inner wall of the low-pressure exhaust port.

[0023] Further technical improvements of the present application are that the template is further provided with an adsorption unit for vacuumizing the driving cavity, the adsorption unit comprises a gas suction port communicated with the driving cavity, an exhaust channel is communicated with the end of the gas suction port, and the low-pressure exhaust port and the exhaust channel are connected with the same vacuum pump through pipelines.

[0024] Further technical improvements of the present application are that the driving cavity is provided with an inlet port above the sealing plate, the inlet port is communicated with purified compressed air to blow the lip plate lip area, and the driving cavity is provided with an exhaust channel away from the inlet port.

[0025] Further technical improvements of the present application are that the end of the machine barrel is provided with a feeding hopper, the machine barrel is connected with an organism below, the discharge end of the mold box is provided with a cutting unit, and the length of the material after calendering, cooling and shaping is cut in the cutting unit.

[0026] A working method of a PVC plate extrusion equipment, the working method comprises the following steps:

[0027] Step one, the molten material enters the tapered channel in the mold box through the feeding port, the movable mold is pushed by the electric push rod to change the forming thickness, and the use state of the two groups of mold lips is switched by the switching unit;

[0028] Step two, when one group of mold lips works, the other group of mold lips is accommodated in the corresponding driving cavity, and then the sealing plate is sealed in the driving cavity by the cavity;

[0029] Step three, the gas bag part is in contact with the flexible sealing gasket by the pushing of the stroke cylinder, the flexible sealing gasket deforms synchronously with the gas bag part, expands in the inflated state and applies a pressing force to the material flow channel, compacts the material and removes the entrained gas;

[0030] Step four, the gas is sucked away by the low-pressure exhaust port after filtering through the ceramic foam plate, and the residual gas in the two groups of mold lips is sucked out by the gas suction port and the exhaust channel, so that the gas is prevented from remaining in the forming cavity to affect the extrusion quality.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] 1、By setting two groups of die lip, switching unit and sealing unit, two groups of die lip in the mold plate switch state according to production demand, one group of lip plate is in use state, the longest side of its cam contacts with the pressure roller frame, while the other group of lip plate is hidden in the corresponding driving cavity and does not participate in the extrusion work, the shortest side of the other cam contacts with the corresponding pressure roller frame, that is, one group of die lip is in use state, the other group is in closed state, and the sealing plate seals the die lip in closed state; in the closed state, by rotating the threaded rod, the driving sleeve frame slides along the cavity limit until it slides to the position of the inclined table, the inclined table and the end surface of the movable plate form a push contact, under the inclined surface, the movable plate slides in the vertical direction of the sleeve frame, so that the sealing plate leaves the inside of the cavity, preventing high temperature melt from penetrating into the driving cavity to cause pollution and bonding, avoiding the pollution of unused die lip group by molten material; switching the die lip group without stopping the machine, realizing the rapid switching of different plate specifications, greatly reducing the mold changing time and manual operation frequency, improving the continuity and flexible production capacity of the extrusion process, and effectively sealing the die lip in non-working state to prevent melt pollution;

[0033] 2、By setting low pressure exhaust port and adsorption unit, the material is degassed in the compression area of the extrusion channel, and the residual gas in the two groups of die lip is also extracted through the suction port and exhaust channel, preventing gas inclusions from entering the extruded material, avoiding quality defects such as air bubbles in the molding process, and improving the structural density and surface finish of the plate product;

[0034] 3、By setting the compression unit, the air bag connected to the lower end of the stroke cylinder is driven to move downward as a whole and contacts with the flexible sealing pad, the air bag is inflated and expands, applying pressure to the flexible sealing pad in the vertical direction, the flexible sealing pad is pressed and fitted between the movable die and the mold box to form a high pressure sealing area, compacting the material and excluding the gas entrained during the extrusion process;

[0035] 4、By switching to the storage state, purified compressed gas is continuously or intermittently sent to the lip area of the lip plate, the lip area is washed with gas, effectively removing residual melt, volatile components and carbide particles, preventing impurities from mixing into the melt channel when the die lip is enabled, thereby improving the cleanliness and molding quality of the plate product. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to facilitate the understanding of those skilled in the art, the present application will be further described below with reference to the accompanying drawings.

[0037] Figure 1 is the schematic diagram of the external structure of the present application;

[0038] Figure 2 is the schematic diagram of the internal structure of the mold box of the present application;

[0039] Figure 3 is the schematic diagram of theFigure 2 A magnified view of a section at point A in the middle;

[0040] Figure 4 For the present invention Figure 2 A magnified view of a section at point B in the middle;

[0041] Figure 5 For the present invention Figure 2 A magnified view of a section at point C;

[0042] Figure 6 This is a schematic diagram of the installation structure of the discharge channel of the present invention.

[0043] In the diagram: 1. Machine body; 2. Feed hopper; 3. Machine barrel; 4. Feed inlet; 5. Cutting unit; 6. Die box; 7. Flexible sealing gasket; 8. Airbag component; 9. Stroke cylinder; 10. Gradient channel; 11. Electric push rod; 12. Extrusion channel; 13. Low-pressure exhaust port; 14. Heat radiation plate; 15. Ceramic foam board; 16. Cavity; 17. Lip plate; 18. Spring; 19. Air extraction port; 20. Exhaust channel; 21. Drive shaft; 22. Cam; 23. Pressure roller frame; 24. Inclined platform; 25. Threaded rod; 26. Sliding sleeve frame; 27. Movable plate; 28. Sealing plate; 29. ​​Piston sleeve; 30. Drive chamber; 31. Inlet; 32. Discharge channel. Detailed Implementation

[0044] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0045] Please see Figures 1-6 As shown, the present invention provides a PVC sheet extrusion device, including a barrel 3, the discharge end of the barrel 3 is connected to a feed inlet 4, one end of the feed inlet 4 is connected to a die box 6 for extruding sheet, the interior of the die box 6 is provided with a tapered channel 10 communicating with the feed inlet 4, and one side of the tapered channel 10 is provided with a template for extrusion.

[0046] The template contains two sets of die lips that are used at different times;

[0047] Each set of mold lips includes a drive cavity 30 provided on the template. A lip plate 17 is slidably installed in the drive cavity 30. A pressure roller frame 23 is installed at the end of the lip plate 17, and a spring 18 is sleeved on one side of the end of the lip plate 17. The end of the spring 18 is fixed to the inner cavity of the drive cavity 30.

[0048] The upper and lower lip plates 17 form a set of mold lips, and the two lip plates 17 are used in conjunction.

[0049] The template is equipped with a switching unit for switching the usage status of the two sets of mold lips;

[0050] The switching unit comprises a driving shaft 21 driven by an internal motor, an outer part of the driving shaft 21 is sleeved with two cams 22 respectively, the two cams 22 are angularly spaced 180 degrees, and the cam 22 is in abutting contact with a corresponding pressure wheel frame 23;

[0051] A sealing unit for sealing each driving cavity 30 is arranged on one side of the template close to the corresponding die lip;

[0052] The sealing unit comprises a cavity 16, a threaded rod 25 is installed in the cavity 16, an outer part of the threaded rod 25 is sleeved with a sliding sleeve frame 26 which is limited to slide in the cavity 16, and a movable plate 27 is slidably arranged in the sliding sleeve frame 26, and one side of the movable plate 27 is provided with a sealing plate 28;

[0053] The cavity 16 is provided with inclined tables 24 with the same inclination angle at the top and the bottom of the cavity 16, and two end faces of the movable plate 27 are in abutting contact with corresponding inclined tables 24;

[0054] A piston sleeve 29 is installed on an outer part of the movable plate 27, and the piston sleeve 29 is limited to slide with the sliding sleeve frame 26;

[0055] Two groups of die lips in the template are switched according to production requirements, that is, the driving shaft 21 drives the cam 22 to rotate, the pressure wheel frame 23 in contact with the cam 22 is limited to move in the vertical direction, thereby driving the lip plate 17 to move up and down in the corresponding driving cavity 30;

[0056] When one group of lip plates 17 is in a use state, the longest side of the cam 22 thereof is in contact with the pressure wheel frame 23, and the other group of lip plates 17 is hidden in the corresponding driving cavity 30 and does not participate in the extrusion work, and the shortest side of the other cam 22 is in contact with the corresponding pressure wheel frame 23, that is, one group of die lips is in a use state, and the other group is in a closed state and is sealed by the sealing plate 28;

[0057] In the closed state, the sliding sleeve frame 26 is driven to slide along the cavity 16 by rotating the threaded rod 25, until the sliding sleeve frame 26 slides to the position of the inclined table 24, the end face of the movable plate 27 is in abutting contact with the inclined table 24, under the abutting contact, the movable plate 27 slides along the vertical direction of the sliding sleeve frame 26, and the piston sleeve 29 installed thereon moves vertically, thereby making the sealing plate 28 move in the vertical direction, and the movable plate 27 drives the sealing plate 28 to move downward and away from the inside of the cavity 16, preventing the high-temperature melt from penetrating into the driving cavity 30 to cause pollution and adhesion, and avoiding the unused die lip group from being polluted by the molten material;

[0058] The die lip groups are switched without stopping, different plate specifications are quickly switched, the die changing time and the manual operation frequency are greatly reduced, the continuity and the flexible production capacity of the extrusion process are improved, and the die lips in the non-working state can be effectively sealed to prevent the melt from being polluted.

[0059] Referring to Figure 2 As shown, the mold plate includes a fixed mold, a movable mold is arranged above the fixed mold and arranged with an extrusion channel 12 between the fixed mold and the movable mold;

[0060] The top of the inner cavity of the mold box 6 is provided with an electric push rod 11 for pushing the movable mold to move vertically, and one side of the movable mold is connected with a flexible sealing gasket 7, the end of the flexible sealing gasket 7 is fixed with the inner wall of the mold box 6 and always keeps a close state with the movable mold to move up and down, so as to prevent molten material from leaking or air from entering;

[0061] The upper part of the tapered channel 10 is provided with a compression unit;

[0062] The compression unit includes a stroke air cylinder 9 installed at the top of the inner cavity of the mold box 6, and the pushing end of the stroke air cylinder 9 is provided with an air bag 8, which is in contact with the flexible sealing gasket 7;

[0063] The movable mold is pushed by the electric push rod 11 to move up and down in the vertical direction, so as to adjust the height and extrusion pressure of the extrusion channel 12, and accurately adjust the gap of the extrusion channel 12 to adapt to the extrusion thickness of different materials or products;

[0064] The movable mold moves up and down in the vertical direction to adjust the height and extrusion pressure of the extrusion channel 12;

[0065] The air bag 8 connected to the lower end of the stroke air cylinder 9 is driven to move downward as a whole and is in contact with the flexible sealing gasket 7, the air bag 8 is inflated and expanded, and the flexible sealing gasket 7 is pressed to form a high-pressure sealing area between the movable mold and the mold box 6 in the vertical direction, so as to compact the material and exclude the gas entrained in the extrusion process.

[0066] Referring to Figure 4 As shown, a low-pressure exhaust port 13 is arranged on one side of the movable mold adjacent to the tapered channel 10, a ceramic foam plate 15 is installed at the gas inlet end of the low-pressure exhaust port 13, and a heat radiation plate 14 is embedded and installed on the inner wall of the low-pressure exhaust port 13, so as to maintain the temperature stability in the low-pressure exhaust port 13 and prevent coking caused by gas condensation or melt adhesion;

[0067] The ceramic foam plate 15 has a porous filtering structure, which allows gas to pass through while blocking high-temperature melt and solid particles from entering the low-pressure exhaust port 13, preventing blockage and pollution;

[0068] The mold plate is also provided with a suction unit for vacuumizing the driving cavity 30, the suction unit includes an air outlet 19 communicated with the driving cavity 30, the end of the air outlet 19 is communicated with an exhaust channel 20, and the low-pressure exhaust port 13 and the exhaust channel 20 are connected with the same vacuum pump through pipelines;

[0069] In the mold lip switching, using or storage state, the gas in the driving cavity 30 is synchronously pumped out, so as to avoid the gas accumulation or penetration between the mold lips and into the main melt flow channel;

[0070] The material is degassed in the compression area of the extrusion channel 12, and the residual gas in the two groups of mold lips is pumped out through the exhaust port 19 and the exhaust channel 20, so as to prevent the gas from being mixed into the extruded material, avoid the quality defects such as bubbles, interlayer, whitening or uneven density in the molding process, and significantly improve the structural density and surface smoothness of the plate product.

[0071] Referring to Figure 6 As shown in the figure, the driving cavity 30 is provided with an inlet 31 above the sealing plate 28, which blows clean compressed air towards the lip area of the lip plate 17, and the side of the driving cavity 30 away from the inlet 31 is provided with an exhaust channel 32 connected with an external collection pipeline, which is used for leading out the sweeping tail gas containing heat volatiles or particulate matter;

[0072] In the switching storage state, clean gas is continuously or intermittently sent to the lip area of the lip plate 17 to realize the sweeping and cleaning function;

[0073] In the mold lip switching or closing state, the lip area is washed with gas, which effectively removes the residual melt, volatile components and carbide particles, prevents impurities from mixing into the melt channel when the mold lip is started, and improves the cleanliness and molding quality of the plate product, and reduces the lip maintenance frequency.

[0074] The end of the cylinder 3 is provided with a feeding hopper 2, the lower part of the cylinder 3 is provided with a machine body 1, the discharge end of the mold box 6 is provided with a cutting unit 5, and the extruded plate after the calendering and cooling is cut to a fixed length in the cutting unit 5;

[0075] The extruded plate after discharging enters the calendering and cooling in sequence, the thickness of the plate is controlled and the temperature is stabilized, and finally the plate after the calendering and cooling is conveyed to the cutting unit 5, and the plate product is cut to a fixed length, so that the size of the obtained molded plate meets the batch processing requirements.

[0076] The working method of the PVC plate extrusion equipment provided by the application comprises the following steps:

[0077] Step one, the molten material enters the tapered channel 10 in the mold box 6 through the feeding port 4, the movable mold is pushed by the electric push rod 11 to change the molding thickness, and the use state of the two groups of mold lips is switched by the switching unit;

[0078] Step two, when one group of mold lips works, the other group of mold lips is stored in the corresponding driving cavity 30, and then the sealing plate 28 is sealed in the driving cavity 30 by the cavity body 16;

[0079] Step three, through the push of the stroke cylinder 9, the air bag 8 is in contact with the flexible sealing pad 7, the flexible sealing pad 7 is deformed synchronously with the air bag 8, expands in the inflated state and applies a pressing force to the material flow channel, compacts the material and removes the entrained gas;

[0080] Step four, the filtered gas is extracted by the low-pressure exhaust port 13, and the residual gas in the two groups of die lips is extracted by the suction port 19 and the exhaust channel 20, so that the gas is prevented from being retained in the forming cavity to affect the extrusion quality.

[0081] In use, the two groups of die lips in the mold plate are switched according to production requirements, one group of lip plates 17 is in use, the longest side of the cam 22 is in contact with the pressure roller frame 23, and the other group of lip plates 17 is hidden in the corresponding driving cavity 30 and does not participate in the extrusion work, the shortest side of the other cam 22 is in contact with the corresponding pressure roller frame 23, that is, one group of die lips is in use and the other group is in closed state and is sealed by the sealing plate 28; in the closed state, by rotating the threaded rod 25, the sliding sleeve frame 26 is limited to slide along the cavity 16 until it slides to the position of the inclined table 24, the inclined table 24 and the end surface of the movable plate 27 form a pushing contact, under the action of the inclined surface, the movable plate 27 slides in the vertical direction of the sliding sleeve frame 26, so that the sealing plate 28 leaves the inside of the cavity 16, preventing the high-temperature melt from penetrating into the driving cavity 30 to cause pollution and bonding, and avoiding the unused die lip group from being polluted by the molten material; the die lip group is switched without stopping, different plate specifications are quickly switched, the mold changing time and the manual operation frequency are greatly reduced, the continuity of the extrusion process and the flexible production capacity are improved, and the unused die lip can be effectively sealed to prevent melt pollution;

[0082] By setting the low-pressure exhaust port 13 and the adsorption unit, the material is degassed in the compression area of the extrusion channel 12, and the residual gas in the two groups of die lips is extracted by the suction port 19 and the exhaust channel 20, preventing the gas from being mixed into the extruded material and avoiding quality defects such as bubbles in the molding process, and improving the structural density and surface finish of the plate product;

[0083] By setting the compression unit, the air bag 8 connected to the lower end driven by the stroke cylinder 9 moves downward as a whole and comes into contact with the flexible sealing pad 7, the air bag 8 inflates and expands, applies pressure to the flexible sealing pad 7 in the vertical direction, and the flexible sealing pad 7 is pressed and tightly fitted between the movable die and the mold box 6 to form a high-pressure sealing area, which compacts the material and removes the entrained gas during the extrusion process;

[0084] By switching to the storage state, the purified compressed gas is continuously or intermittently sent to the lip area of the lip plate 17, the lip area is gas washed, the residual melt, volatile components and carbide particles are effectively removed, and impurities are prevented from mixing into the melt channel when the mold lip is opened, thereby improving the cleanliness and forming quality of the plate product.

[0085] The above is only a preferred embodiment of the present application, not any form of limitation on the present application. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution range of the present application. Any simple modification, equivalent change and modification of the above embodiments made according to the technical essence of the present application, without departing from the technical solution content of the present application, still belongs to the scope of the technical solution of the present application.

Claims

1. A PVC sheet extrusion plant comprising a barrel (3) having a delivery end which is connected by a delivery port (4) to a die box (6) for extruding a sheet, characterised in that: The inside of the mold box (6) is provided with a tapered channel (10) communicated with the feeding inlet (4), one side of the tapered channel (10) is provided with a mold plate for extrusion; The mold plate is provided with two groups of mold lips which are not used at different times; Each group of mold lips comprises a driving cavity (30) provided on the mold plate, a lip plate (17) is slidingly installed in the driving cavity (30), the end of the lip plate (17) is provided with a pressure roller frame (23), and one side of the end of the lip plate (17) is sleeved with a spring (18), the end of the spring (18) is fixed with the inner cavity of the driving cavity (30); The mold plate is provided with a switching unit for switching the use state of the two groups of mold lips; The switching unit comprises a driving shaft (21) driven by an internal motor, the outer part of the driving shaft (21) is sleeved with two cams (22) respectively, the angle interval of the two cams (22) is 180 degrees, and the cam (22) is abutted with the corresponding pressure roller frame (23); The mold plate is provided with a sealing unit near the side corresponding to the mold lip for sealing each driving cavity (30); The sealing unit comprises a cavity (16), a threaded rod (25) is installed in the cavity (16), the outer part of the threaded rod (25) is sleeved with a sliding sleeve frame (26) which is limited to slide in the cavity (16), a movable plate (27) is slidingly arranged in the sliding sleeve frame (26), and one side of the movable plate (27) is provided with a sealing plate (28); The top and bottom of the inner cavity of the cavity (16) is provided with inclined tables (24) with the same inclination angle, and the two end faces of the movable plate (27) are abutted with the corresponding inclined tables (24); The outer part of the movable plate (27) is provided with a piston sleeve (29), and the piston sleeve (29) is limited to slide with the sliding sleeve frame (26).

2. The PVC sheet extrusion apparatus according to claim 1, characterized in that, The mold plate comprises a fixed mold, a movable mold is arranged above the fixed mold and is lifted, and an extrusion channel (12) is arranged between the fixed mold and the movable mold.

3. The PVC sheet extrusion apparatus according to claim 2, wherein The top of the inner cavity of the mold box (6) is provided with an electric push rod (11) for pushing the vertical movement of the movable mold, one side of the movable mold is connected with a flexible The end of the flexible sealing gasket (7) is fixed with the inner wall of the mold box (6).

4. The PVC sheet extrusion apparatus according to claim 3, wherein The upper part of the tapered channel (10) is provided with a compression unit; The compression unit comprises a stroke air cylinder (9) installed at the top of the inner cavity of the mold box (6), the pushing end of the stroke air cylinder (9) is provided with an air bag (8), and the air bag (8) is in contact with the flexible sealing gasket (7).

5. The PVC sheet extrusion apparatus according to claim 4, wherein The side of the movable mold adjacent to the tapered channel (10) is provided with a low-pressure exhaust port (13), the air inlet end of the low-pressure exhaust port (13) is provided with a ceramic foam plate (15), and the inner wall of the low-pressure exhaust port (13) is embedded with a heat radiation plate (14).

6. The PVC sheet extrusion apparatus according to claim 5, wherein, The mold plate is also provided with a suction unit for pumping the driving cavity (30), the suction unit comprises an air exhaust port (19) communicated with the driving cavity (30), the end of the air exhaust port (19) is communicated with an exhaust channel (20), and the low-pressure exhaust port (13) and the exhaust channel (20) are connected with the same vacuum pump through pipelines.

7. The PVC sheet extrusion apparatus according to claim 6, wherein The driving cavity (30) is provided with an inlet (31) above the sealing plate (28), which blows the lip plate (17) lip area with purified compressed air, and one side of the driving cavity (30) away from the inlet (31) is provided with an exhaust channel (32).

8. The PVC sheet extrusion apparatus according to claim 7, wherein, The end of the machine barrel (3) is provided with a feeding hopper (2), the lower part of the machine barrel (3) is connected with the organism (1), the discharge end of the mold box (6) is provided with a cutting unit (5), and the length cutting is performed in the cutting unit (5) after the calendering cooling and shaping.

9. The method of claim 8, wherein the PVC sheet extrusion apparatus further comprises a second PVC sheet extrusion apparatus, and the method further comprises: extruding a second PVC sheet from the second PVC sheet extrusion apparatus; and cutting the second PVC sheet into a second plurality of PVC sheets. The working method comprises the following steps: Step one, the molten material enters the tapered channel (10) in the mold box (6) through the feeding port (4), the movable mold is pushed by the electric push rod (11), the forming thickness is changed, and the use state of the two groups of mold lips is switched by the switching unit; Step two, when one group of mold lips works, the other group of mold lips is accommodated in the corresponding driving cavity (30), then the sealing plate (28) is sealed by the cavity (16) into the driving cavity (30); Step three, the gas bag member (8) is in contact with the flexible sealing gasket (7) by the pushing of the stroke air cylinder (9), the flexible sealing gasket (7) deforms synchronously with the gas bag member (8), expands in the inflation state and applies the pressing force to the material flow channel, compacts the material and removes the entrained gas; Step four, the gas is removed by the low-pressure exhaust port (13) after being filtered by the ceramic foam plate (15), the residual gas in the two groups of mold lips is removed by the exhaust port (19) and the exhaust channel (20), and the gas is prevented from being retained in the forming cavity to affect the extrusion quality.

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