High pressure slip casting process in quartz crucible

Abstract

A quartz crucible high-pressure slip casting process, the specific process steps are: model compaction - slurry pressurization - slip casting - heat conduction oil heating - green body stripping - model self-cleaning - crucible high-pressure slip casting process operation flow is completed.The forming process disclosed in the application has the advantages that the crucible high-pressure slip casting process is short in time, the crucible green body structure is uniform and compact, the inner and outer walls of the crucible are smooth, the crucible green body is rapidly hardened through the heating function of the model outside, demolding is convenient, and the forming efficiency is high.

Description

Technical Field

[0001] This invention relates to the field of slurry casting, specifically a high-pressure slurry casting process using a quartz crucible. Background Technology

[0002] Quartz crucibles are consumables used in the photovoltaic industry for pulling monocrystalline silicon. The annual demand for crucibles in the monocrystalline silicon industry nationwide is around 2.8-3.6 million, while the current domestic annual production capacity cannot meet the demand of the domestic monocrystalline silicon industry.

[0003] Currently, domestic quartz crucible manufacturers use equipment and processes with low automation levels, resulting in low production efficiency. The production process relies on manual operation, leading to numerous air bubbles inside the crucible, poor particle assembly, large shrinkage during high-temperature melting, and a short actual service life.

[0004] Quartz crucibles are generally produced and formed using two methods: grouting or casting with plaster molds.

[0005] Firstly, the gypsum mold casting method is commonly used in the production of quartz crucibles. The casting method relies on the gypsum mold to absorb water for drying, which results in a long demolding time. The demolding time for gypsum mold casting is generally 7-8 hours, which is very low. The production volume cannot meet the sales orders.

[0006] Secondly, the casting process uses steel molds and a large amount of adhesive in the crucible. The blank can solidify and form during the production process, which improves its strength and makes it easy to demold quickly. However, the surface finish of the inner wall of the crucible does not meet the technical requirements, so a coating must be added to improve the surface finish of the inner wall. Summary of the Invention

[0007] This invention addresses the problems in the prior art by providing a high-pressure slurry casting process for quartz crucibles that combines heating and self-cleaning.

[0008] The technical solution adopted in this invention is: a high-pressure slip casting process for quartz crucibles, the specific process steps of which are as follows:

[0009] S1: Model clamping

[0010] The hydraulic station of the crucible high-pressure grouting molding machine is started, the oil cylinder drives the model clamping plate to descend, the upper part of the model contacts the lower part of the model, and the pressure continues to be increased to 18-20MPa, and the oil cylinder stops working;

[0011] S2: Slurry pressurization

[0012] Open the slurry pressure valve and start the hydraulic slurry press to begin pressurization. The slurry is pumped out by the hydraulic slurry press and enters the mold body through the slurry inlet at the bottom of the crucible high-pressure grouting mold via the pipeline. After grouting is stopped, the slurry pressure valve is closed and the hydraulic slurry press stops working.

[0013] S3: Grouting

[0014] Open the slurry supply inlet valve, the hydraulic slurry press starts, the oil cylinder drives the piston of the pressure tank to rise upward, the slurry in the slurry mixing tank enters the cylinder of the hydraulic slurry press through the pipeline, the oil cylinder drives the piston of the pressure tank to rise to the upper dead point, and the hydraulic slurry press stops working;

[0015] When the slurry supply inlet valve is closed, the hydraulic slurry press is restarted. The oil cylinder drives the piston of the pressurizing tank to descend and pressurize the slurry, thus starting the slurry injection molding process.

[0016] S4: Heat transfer oil supply

[0017] Open the valve of the model's heat transfer oil pipeline, start the circulation pump, and begin heating the upper and lower parts of the model. The temperature of the heat transfer oil is 100-110 degrees Celsius, and the temperature of the crucible blank inside the model reaches 80-85 degrees Celsius. The heating time for the upper and lower parts of the model is 20-25 minutes. Then stop heating the model.

[0018] S5: Green body peeling

[0019] After the model is heated, compressed air enters the lower part of the model through the drainage channel to perform gas stripping between the ultrafine porous resin permeation layer of the model and the crucible blank.

[0020] S6: Model Self-Cleaning

[0021] Turn on the water purification valve. The purified water enters through the internal drainage pipe of the model, passes through the silica sand layer and the ultra-fine porous resin layer, and enters the inner wall of the model to repeatedly rinse the upper and lower parts of the model. The water rinsing time is 1 minute.

[0022] Close the water valve, open the three-way valve of the slurry inlet at the bottom of the model to drain the water accumulated during model cleaning to the outside of the model, open the compressed air valve, and blow away the residual slurry outside the silica sand layer and ultra-fine pore resin layer through the internal drainage pipe of the model before closing the compressed air valve.

[0023] The high-pressure grouting molding process for crucibles has been completed.

[0024] As a preferred technical solution: In step S2, the initial grout pressure is 0.1 MPa, and after 1 minute the grout pressure is increased to 1.5 MPa for high-pressure grouting, and the high-pressure grouting time is 5 minutes.

[0025] As a preferred technical solution: In step S5, when gas stripping is performed, a gas gap is generated between the crucible blank and the model. The pressure of compressed air is set to 0.1-0.15MPa. After 5 seconds of air supply, the hydraulic cylinder of the model clamping plate is opened and the upper part of the model begins to lift. After 10 seconds of compressed air supply to the lower part of the model, the air supply is stopped. At this time, the crucible blank is adsorbed on the upper part of the model and has completely separated from the lower part of the model.

[0026] The hydraulic cylinder stops when the upper part of the model, which is holding the crucible blank, is raised to a position 150mm above the lowest point of the model.

[0027] As a preferred technical solution: the tooling plate is placed at the bottom of the crucible blank, the hydraulic cylinder of the model clamping plate is opened and lifted, at which time the vacuum suction of the upper part of the model is stopped and compressed air is supplied to the upper part of the model. The air supply pressure is 0.5-0.7MPa, which makes the crucible blank separate from the model's ultra-fine porous resin permeation layer. The crucible blank is separated from the model and falls on the support plate. The hydraulic cylinder stops working when the lowest point of the upper part of the model rises to 100mm above the crucible blank. The crucible blank is completely demolded from the model and the crucible blank is removed.

[0028] As a preferred technical solution: in step S6, the compressed air pressure is 0.3 MPa and the compressed air purging time is 30 seconds.

[0029] Compared with the prior art, the molding process disclosed in this invention has the following advantages: the crucible high-pressure injection molding time is short, the crucible blank has a uniform and compact particle structure, the inner and outer walls of the crucible become smooth, the crucible blank is quickly hardened by the heating function designed on the outside of the mold, demolding is convenient, and the molding efficiency is high. Attached Figure Description

[0030] Figure 1 This is a process flow diagram of the present invention.

[0031] Figure 2 This is a front view of the high-pressure grouting molding machine for crucibles in this invention.

[0032] Figure 3 for Figure 2 Side view.

[0033] Figure 4 This is a front view of the hydraulic slurry press in this invention.

[0034] Figure 5 for Figure 4 Side view.

[0035] Figure 6 This is a schematic diagram of the structure of the model in this invention.

[0036] Figure 7 for Figure 6 A cross-sectional structural diagram.

[0037] Figure 8 This is a schematic diagram of the upper part of the model.

[0038] Figure 9 This is a schematic diagram of the side view of the upper part of the model.

[0039] Figure 10This is a schematic diagram of the lower part of the model.

[0040] In the diagram: 1. Crucible high-pressure grouting molding machine; 2. Hydraulic grout press; 3. Model. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] See appendix Figure 1 The specific steps of the high-pressure slurry casting process for crucibles disclosed in this invention are as follows:

[0043] S1 Model Clamping: The hydraulic station of the crucible high-pressure grouting heating molding machine is started, and the oil cylinder drives the model clamping plate to descend to the upper part of the model. The lower part contacts the pressure and applies pressure to 18MPa, at which point the oil cylinder stops working.

[0044] S2 Slurry Pressurization: Open the slurry pressure valve and start the hydraulic slurry pressurizer to begin pressurization. The slurry enters directly into the crucible through the lower pipe of the hydraulic slurry pressurizer. The model has a bottom slurry inlet, and the slurry enters the empty slurry body of the model. The slurry pressure is 0.1 MPa at this time. After 1 minute, the slurry pressure increases to 1.5 MPa for high-pressure grouting. The high-pressure grouting time is 5 minutes. After that, the high-pressure grouting is stopped, the slurry pressure valve is closed, and the hydraulic slurry pressurizer stops working.

[0045] S3 grouting:

[0046] Open the slurry supply valve of the pipeline connecting the slurry mixing tank to the hydraulic slurry press. The rising relay valve in the hydraulic slurry press will open. The oil cylinder will drive the piston of the pressurizing tank to rise upward. The slurry in the slurry mixing tank will enter the cylinder of the hydraulic slurry press through the pipeline to be pressurized. After the piston of the pressurizing tank rises to the upper dead point, it will stop working and the slurry inlet valve will be closed.

[0047] The solenoid valve for lowering in the hydraulic slurry press opens, and the hydraulic cylinder drives the piston of the pressure tank to descend, pressurizing the slurry and initiating the slurry injection molding process. The up and down strokes of the hydraulic slurry press are controlled by limit proximity switches.

[0048] S4 Thermal Oil Heating: Open the thermal oil pipeline valve on the model, and the circulation pump will start running to heat the upper and lower parts of the model. The temperature of the thermal oil should be 100-110 degrees Celsius. The model heating system is automatically controlled by a constant-temperature electric heater, and the temperature can be adjusted according to actual needs. The temperature of the crucible blank inside the model should reach 80-85 degrees Celsius, allowing the plant organic adhesive remaining in the crucible blank slurry to gelatinize and the coarse and fine quartz particles in the blank to bond and solidify, achieving rapid hardening of the crucible blank. The heating time for the upper and lower parts of the model should be 20-25 minutes, after which heating should be stopped. Adjust the model heating time according to the slurry properties and the stiffness of the crucible blank.

[0049] S5 Blank Peeling: After the model is heated, compressed air enters through the drainage channel at the bottom of the model to perform gas peeling between the ultra-fine porous resin permeation layer of the model and the crucible blank, creating a gas gap between the crucible blank and the model. The compressed air pressure is set to 0.1-0.15MPa. After supplying air for 5 seconds, the vacuum pump starts working pneumatically, and the upper part of the model is evacuated by the model drainage pipe to prevent the crucible blank from separating from the upper part of the model. The hydraulic cylinder of the model clamping plate is activated, and the upper part of the model begins to lift. The lifting speed of the hydraulic cylinder can be set according to the demolding situation. After supplying compressed air to the bottom of the model for 10 seconds, the air supply stops. At this time, the crucible blank is adsorbed on the upper part of the model and has been attached to the mold. When the model is completely detached, the upper part of the model, adsorbing the crucible blank, is raised to 150mm above the lowest point of the model. The hydraulic cylinder stops, and the blank is automatically removed mechanically or manually placed at the bottom of the crucible blank using a special tooling plate. The hydraulic cylinder of the model clamping plate is opened and raised. At this time, the vacuum suction at the upper part of the model stops, and compressed air is supplied to the upper part of the model at a pressure of 0.5-0.7MPa. This causes the crucible blank to peel off from the ultra-fine porous resin permeation layer of the model, and the crucible blank is detached from the model. The crucible blank falls onto the support plate. When the lowest point of the upper part of the model rises to 100mm above the crucible blank, the hydraulic cylinder stops, and the crucible blank is completely demolded from the model. The crucible blank is then removed.

[0050] S6 Model Self-Cleaning: Open the water valve and let clean water flow through the internal drainage pipe of the model. Note: Water supply pressure is 0.3MPa. The clean water passes through the silica sand layer and the ultra-fine porous resin layer to enter the inner wall of the model and backwash the upper and lower parts of the model to clean the attachments on the inner wall of the model. The clean water cleaning time is 1 minute. Close the water valve and open the three-way valve of the slurry inlet at the bottom of the model to drain the water accumulated in the model cleaning to the outside of the model. Open the compressed air valve and blow away the residual slurry on the outside of the silica sand layer and ultra-fine porous resin layer through the internal drainage pipe of the model. The compressed air pressure is 0.3MPa and the compressed air blowing time is 30 seconds. Close the compressed air valve.

[0051] The overall equipment crucible high-pressure grouting heating molding process is complete.

[0052] See appendix Figure 2-3The crucible high-pressure slurry casting molding machine used in the molding process includes a base 1-1, a main frame 1-4, a hydraulic cylinder 1-5, a limit detection switch 1-7, a model heater 1-8, a vacuum pump 1-9, a linear track 1-10, a slider 1-11, a lifting pressure plate 1-12, a slurry mixing tank 1-13, a first valve 1-14, a conveying pipe 1-15, a slurry press 1-16, and a second valve 1-17. The main frame 1-4 is connected to the base 1-1, and the hydraulic cylinder 1-5 is fixedly connected to the top of the main frame 1-4. Linear tracks 1-10 are fixedly connected to the walls of both chambers inside the main frame 1-4. Slider 1-11 is slidably connected to each linear track 1-10. A lifting pressure plate 1-12 is fixedly connected between sliders 1-11; the lifting pressure plate 1-12 is fixedly connected to the output end of the oil cylinder 1-5; the limit detection switch 1-7 is connected to the upper end of the chamber inside the main frame 1-4; the model heater 1-8 and the vacuum pump 1-9 are connected to the left side of the main frame 1-4; the slurry mixing tank 1-13 and the slurry press 1-16 are located on one side of the base 1; the bottom end of the slurry mixing tank 1-13 is fixedly connected to the first valve 1-14; the first valve 1-14 is connected to the conveying pipe 1-15 and the second valve 1-17 in sequence; the slurry press 1-16 is connected to the conveying pipe 1-15 between the first valve 1-14 and the second valve 1-17.

[0053] The crucible high-pressure grouting molding machine also includes a hydraulic station 1-2, an electrical box 1-3, and a hydraulic oil pipeline 1-6; the hydraulic station 1-2 and the electrical box 1-3 are connected to the right side of the main frame 1-4; the hydraulic station 1-2 is connected to the oil cylinder 1-5 and the slurry press 1-16 through the hydraulic oil pipeline 1-6.

[0054] See appendix Figure 4-5The hydraulic slurry press used in the molding process includes a frame 2-1, a top plate 2-2, a slurry pressurizing cylinder body 2-3, slurry inlet and outlet 2-4, a hydraulic station 2-5, a rod chamber oil inlet pipe 2-6, a rodless chamber oil inlet pipe 2-7, a fixed pressure plate 2-8, a cylinder rod 2-9, a slurry pressurizing cylinder flange 2-10, a hollow rod inlet channel 2-11, a cylinder piston 2-12, a piston sealing ring 2-13, and a cylinder body 2-14. 14. Piston 2-15 and sealing ring 2-16 of the mud pressurizing cylinder; a top plate 2-2 is fixedly connected to the top of the frame 2-1; a mud pressurizing cylinder body 2-3 is fixedly connected to the middle of the frame 2-1; a mud inlet / outlet 2-4 is fixedly connected to the bottom of the mud pressurizing cylinder body 2-3; a mud pressurizing cylinder flange 2-10 is provided on the top of the mud pressurizing cylinder body 2-3; a fixed pressure plate 2-8 is connected to the center of the lower surface of the top plate 2-2. A cylinder rod 2-9 is fixedly connected to the fixed pressure plate 2-8. The cylinder rod 2-9 has a hollow oil inlet passage 2-11. A cylinder piston 2-12 is connected to the end of the cylinder rod 2-9. A piston sealing ring 2-13 is connected to the cylinder piston 2-12. A mud pressurizing cylinder piston 2-15 is provided in the mud pressurizing cylinder body 2-3. A mud pressurizing cylinder sealing ring 2-16 is provided on the outer surface of the upper end of the mud pressurizing cylinder piston 2-15. The piston 2-15 of the mud pressurizing cylinder is equipped with a cylinder body 2-14, and the piston 2-12 of the cylinder is located in the cylinder body 2-14; a hydraulic station 2-5 is fixedly connected to the side of the frame 2-1; the hydraulic station 2-5 is connected to the rod chamber oil inlet pipe 2-6 and the rodless chamber oil inlet pipe 2-7, the rod chamber oil inlet pipe 2-6 is connected to the inside of the cylinder body 2-14, and the rodless chamber oil inlet pipe 2-7 is connected to the hollow rod outlet oil inlet channel 2-11.

[0055] Among them, the piston sealing ring 2-13 and the mud pressurizing cylinder sealing ring 2-16 are both rubber rings; the bottom of the frame 2-1 is provided with support feet; the mud inlet and outlet 2-4 are T-shaped.

[0056] See appendix Figure 4-5The model used in the molding process includes: upper model 3-1, lower model 3-2, upper heat transfer oil inlet 3-5, lower heat transfer oil outlet 3-6, heat transfer oil circulation pipe 3-7, series pipe 3-8, lower heat transfer oil inlet 3-9, lower heat transfer oil outlet 3-10, grout inlet 3-11, upper concrete pouring area 3-16, pipeline 3-17, upper resin silica sand layer 3-18, upper drainage pipeline 3-19, upper microporous resin 3-20, and lower concrete... The model consists of a concrete pouring area 3-21, a lower resin-silica sand layer 3-22, a lower drainage pipe 3-23, and a lower microporous resin layer 3-24. The upper part of the model 3-1 is located above the lower part 3-2. A pipe 3-17 is fixedly connected to the lower surface of the upper part 3-1, with an upper heat transfer oil inlet 3-5 and a lower heat transfer oil outlet 3-6 fixedly connected to both ends of the pipe 3-17. Several heat transfer oil circulation pipes 3-7 are fixedly connected to the outer surface of the lower part 3-2. The circulation pipes 3-7 are connected by a series pipe 3-8. The lower heat transfer oil inlet 3-9 is fixedly connected to the uppermost heat transfer oil circulation pipe 3-7, and the lower heat transfer oil outlet 3-10 is fixedly connected to the lowermost heat transfer oil circulation pipe 3-7. A grout inlet hole 3-11 is provided on the bottom surface of the lower part 3-2 of the model. An upper concrete pouring area 3-16 is provided outside the pipe 3-17, and an upper resin silica sand layer 3-18 is provided outside the upper concrete pouring area 3-16. The upper tree... The upper resin silica sand layer 3-18 is provided with an upper drainage pipe 3-19, and the upper resin silica sand layer 3-18 is provided with an upper microporous resin 3-20 on the outside; the lower concrete pouring area 3-21 is provided on the bottom surface of the lower cavity 3-2 of the model, the lower resin silica sand layer 3-22 is provided in the lower concrete pouring area 3-21, the lower resin silica sand layer 3-22 is provided with a lower drainage pipe 3-23, and the lower resin silica sand layer 3-22 is provided with a lower microporous resin 3-24.

[0057] The model also includes an upper mounting plate 3-3, a lower mounting plate 3-4, locating taper pins 3-12, an upper metal frame 3-13, locating pin holes 3-14, and a lower metal frame 3-15. The upper mounting plate 3-3 is fixedly connected to the four sides of the upper part 3-1 of the model, and the lower mounting plate 3-4 is fixedly connected to the four sides of the bottom end of the lower part 3-2 of the model. Locating taper pins 3-12 are provided around the lower surface of the upper part 3-1, and locating pin holes 3-14 are provided around the upper surface of the lower part 3-2, with the locating taper pins 3-12 corresponding to their respective locating pin holes 3-14. The upper metal frame 3-13 is located on the exterior of the upper part 3-1, and the lower metal frame 3-15 is located on the exterior of the lower part 3-2. The locating taper pins 3-12 are inverted triangular in shape; there are four upper mounting plates 3-3 and four lower mounting plates 3-4.

Claims

1. A high-pressure slip casting process for quartz crucibles, characterized in that, The specific process steps are as follows: S1: Model clamping The hydraulic station of the crucible high-pressure grouting molding machine is started, the oil cylinder drives the model clamping plate to descend, the upper part of the model contacts the lower part of the model, and the pressure continues to be increased to 18-20MPa, and the oil cylinder stops working; S2: Slurry pressurization Open the slurry pressure valve and start the hydraulic slurry press to begin pressurization. The slurry is pumped out by the hydraulic slurry press and enters the mold body through the slurry inlet at the bottom of the crucible high-pressure grouting mold via the pipeline. After grouting is stopped, the slurry pressure valve is closed and the hydraulic slurry press stops working. S3: Grouting Open the slurry supply inlet valve, the hydraulic slurry press starts, the oil cylinder drives the piston of the pressure tank to rise upward, the slurry in the slurry mixing tank enters the cylinder of the hydraulic slurry press through the pipeline, the oil cylinder drives the piston of the pressure tank to rise to the upper dead point, and the hydraulic slurry press stops working; When the slurry supply inlet valve is closed, the hydraulic slurry press is restarted. The oil cylinder drives the piston of the pressurizing tank to descend and pressurize the slurry, thus starting the slurry injection molding process. S4: Heat transfer oil supply Open the valve of the model's heat transfer oil pipeline, start the circulation pump, and begin heating the upper and lower parts of the model. The temperature of the heat transfer oil is 100-110 degrees Celsius, and the temperature of the crucible blank inside the model reaches 80-85 degrees Celsius. The heating time for the upper and lower parts of the model is 20-25 minutes. Then stop heating the model. S5: Green body peeling After the model is heated, compressed air enters through the drainage channel at the bottom of the model to perform gas stripping between the microporous resin permeation layer of the model and the crucible blank; S6: Model Self-Cleaning The model includes an upper part, a lower part, an upper heat transfer oil inlet, a lower heat transfer oil outlet, a heat transfer oil circulation pipe, a series pipe, a lower heat transfer oil inlet, a lower heat transfer oil outlet, a grout inlet, an upper concrete pouring area, pipes, an upper resin silica sand layer, an upper drainage pipe, an upper microporous resin permeation layer, a lower concrete pouring area, a lower resin silica sand layer, a lower drainage pipe, and a lower microporous resin permeation layer. The upper part of the model is located above the lower part, and pipes are fixedly connected inside the upper part. The upper concrete pouring area is located outside the pipes, and the upper resin silica sand layer is located outside the upper concrete pouring area. The upper drainage pipe is located in the upper resin silica sand layer, and the upper microporous resin permeation layer is located on the outer surface of the upper resin silica sand layer. The lower concrete pouring area is located on the bottom surface of the lower cavity, and the lower resin silica sand layer is located above the lower concrete pouring area. The lower drainage pipe is located in the lower resin silica sand layer, and the lower microporous resin permeation layer is located above the lower resin silica sand layer. Open the water purification valve, and the purified water enters through the internal drainage pipe of the model. It penetrates the resin silica sand layer and the microporous resin permeation layer to enter the inner wall of the model, repeatedly rinsing the upper and lower parts of the model. The water rinsing time is 1 minute. Close the water valve, open the three-way valve of the slurry inlet at the bottom of the model to drain the water accumulated during model cleaning to the outside of the model, open the compressed air valve, and blow away the residual slurry outside the silica sand layer and microporous resin penetration layer through the internal drainage pipe of the model before closing the compressed air valve. The high-pressure grouting molding process for crucibles has been completed.

2. The high-pressure slip casting process for quartz crucibles according to claim 1, characterized in that: In step S2, the initial grout pressure is 0.1 MPa, and after 1 minute the grout pressure is increased to 1.5 MPa for high-pressure grouting. The high-pressure grouting time is 5 minutes.

3. The high-pressure slip casting process for quartz crucibles according to claim 1, characterized in that: In step S5, when gas stripping is performed, a gas gap is generated between the crucible blank and the model. The compressed air pressure is set to 0.1-0.15MPa. After 5 seconds of air supply, the hydraulic cylinder of the model clamping plate is opened and the upper part of the model begins to lift. After 10 seconds of compressed air supply to the lower part of the model, the air supply is stopped. At this time, the crucible blank is adsorbed on the upper part of the model and has completely separated from the lower part of the model. The hydraulic cylinder stops when the upper part of the model, which is holding the crucible blank, is raised to a position 150mm above the lowest point of the model.

4. The high-pressure slip casting process for quartz crucibles according to claim 3, characterized in that: Place the pallet at the bottom of the crucible blank, and the hydraulic cylinder of the model clamping plate will be activated to lift it. At this time, the vacuum suction at the top of the model will stop, and compressed air will be supplied to the top of the model at a pressure of 0.5-0.7 MPa. This will cause the crucible blank to peel off from the microporous resin permeation layer of the model, and the crucible blank will detach from the model. The crucible blank will fall onto the pallet. When the lowest point of the top of the model rises to 100 mm above the crucible blank, the hydraulic cylinder will stop working. The crucible blank will be completely demolded from the model and then removed.

5. The high-pressure slip casting process for quartz crucibles according to claim 1, characterized in that: In step S6, the compressed air pressure is 0.3 MPa and the compressed air purging time is 30 seconds.

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