Manufacturing method for one-time forming micro-pressure manned (oxygen) cabin body based on rotational molding process

Abstract

The invention discloses a micro-pressure manned (oxygen) cabin body formed at a time based on a rotational molding process, and belongs to the technical field of medical care equipment. The cabin body is of a hollow structure integrally formed through a rotational molding process, rotational molding grade composite plastic (polyethylene and the like) is selected as a main body material, and the wall thickness is 3-10 mm and is uniform. And a reinforcing rib structure integrally formed with the main body is arranged inside or outside the cabin body. The cabin body is provided with a cabin door frame with a sealing structure, an air inlet connector, an exhaust connector and an observation window installation hole. The cabin body is integrally formed through the rotational molding process, no splicing seam exists, the structural strength is high, and the air tightness is excellent; the plastic material enables the cabin body to be light in weight and resistant to corrosion; the structural stability is further improved through the reinforcing rib design; production efficiency is high, cost is low, and the inner wall is smooth and convenient to clean. The micro-pressure manned (oxygen) cabin effectively overcomes the defects that an existing micro-pressure manned (oxygen) cabin is low in structural strength, low in air tightness, large in weight, prone to corrosion, high in cost, low in production efficiency and the like, and is applied to the health fields of relieving altitude stress, improving human body microcirculation, relieving fatigue, promoting rehabilitation and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of medical care equipment, and particularly relates to a micro-pressure manned (oxygen) cabin body manufacturing method using a rotational molding process for one-time forming. BACKGROUND

[0002] The micro-pressure manned (oxygen) cabin (the working table pressure is 0-50 KPa) helps to alleviate the high altitude reaction, improve the human microcirculation, relieve fatigue, promote rehabilitation and the like by creating an environment slightly higher than the cabin pressure outside the cabin.

[0003] At present, the micro-pressure manned (oxygen) cabin body manufacturing methods mainly include: soft material (PVC, TPU) high-frequency welding or adhesive splicing, low air tightness, lack of cabin body support structure, complex cabin body procedure, zipper cabin door cannot quickly and safely escape; metal material welding forming, heavy weight, inconvenient transportation and installation, high manufacturing cost, explosive fragments flying easily injures people; glass steel hand-pasting / winding structure solidification releases volatile organic compounds (VOC), poor environmental protection, adhesive area is easy to age and air tightness decreases, heavy weight, inconvenient transportation and installation, high manufacturing cost, explosive fragments flying easily injures people.

[0004] The rotational molding process as a plastic hollow product forming technology, by adding plastic powder into the mold, then the mold is constantly rotated along two vertical axes and heated at the same time, so that the plastic powder in the mold is melted and uniformly coated and adhered to the inner surface of the mold, and the product is obtained after cooling and demolding, which has the advantages of one-time forming without welding seam, product without internal stress, not easy to deform, uniform wall thickness, can design reinforcing ribs, strong structure integrity, low mold cost, suitable for small batch and multi-variety production of complex shape products, etc. In the field of special-shaped containers and large storage tanks, the rotational molding process has been maturely applied, and the weather resistance, impact resistance and chemical stability of the product can be improved through material modification, which can well solve the problems existing in the production of micro-pressure manned (oxygen) cabin bodies by traditional process.

[0005] At present, there is no related technology that applies the rotational molding process to the manufacture of micro-pressure manned (oxygen) cabin bodies. Therefore, it is necessary to develop a micro-pressure manned (oxygen) cabin body based on the rotational molding process for one-time forming, to overcome the shortcomings of low cabin body structure strength, poor air tightness, heavy weight, easy corrosion, high cost, explosive fragments flying easily injures people, low production efficiency and the like in the prior art, to fill the technical gap, and to have important application value. SUMMARY

[0006] In order to solve the problems in the background art, the present application provides a micro-pressure manned (oxygen) cabin body manufacturing method based on the rotational molding process for one-time forming, the cabin body is a hollow structure formed by the rotational molding process, and the cabin body is characterized in that:

[0007] The main material of the cabin body is a rotational molding grade (polyethylene, etc.) composite plastic.

[0008] The inside or outside of the cabin body can be provided with a reinforcing rib structure distributed along the circumferential direction and / or the axial direction.

[0009] The cabin body reinforcing rib structure is integrally formed with the cabin body through a rotational molding process.

[0010] The cabin body is provided with a cabin door frame formed by a one-time molding process, and the joint part of the cabin door frame and the cabin door plate is provided with a sealing structure.

[0011] The cabin body can be provided with an air inlet interface for connecting an air source system, an air outlet interface for adjusting the pressure in the cabin, and a transparent observation window mounting hole for observing the situation in the cabin, and the air inlet interface, the air outlet interface and the observation window mounting hole are connected with the cabin body through a sealing connector and ensure air tightness.

[0012] Further, the rotational molding grade (polyethylene, etc.) composite plastic can be added with antioxidants, ultraviolet absorbers, flame retardants, reinforcing fibers, etc. to improve the impact resistance, weather resistance and chemical stability of the cabin body.

[0013] Further, the wall thickness of the cabin body is preferably 3-10 mm, and the wall thickness is uniform to achieve the best balance between structural strength and lightweight.

[0014] Further, the sealing structure includes a sealing groove provided on the cabin door frame, and an elastic sealing rubber strip embedded in the sealing groove, and the elastic sealing rubber strip is preferably made of silicone or rubber.

[0015] Further, the inner wall surface of the cabin body is smooth, which is convenient for cleaning and disinfection.

[0016] Further, the cabin body can also be integrated with a pressure sensor interface, a temperature sensor interface, a lighting system interface or a communication interface as needed, and these interfaces are all sealed. Advantages

[0017] Compared with the prior art, the present application has the following advantages:

[0018] The present application first applies the rotational molding process to the field of micro-pressure load human (oxygen) cabin body manufacturing, overcomes the technical bias of pressure vessel manufacturing methods, and uses the advantages of the rotational molding process to successfully manufacture a micro-pressure load human (oxygen) cabin body with excellent performance, overcoming many drawbacks of the prior art, and having significant innovation and practicality, filling the technical gap.

[0019] Compared with traditional metal welding, fiberglass hand lay-up / winding and other processes, rotational molding has significant advantages such as one-time molding without weld seams, strong structural integrity, good wall thickness uniformity, high material utilization and short production cycle. It can effectively solve technical problems such as poor airtightness, large weight, high cost and insufficient safety in the manufacturing of micro-pressure manned (oxygen) chambers.

[0020] Significantly improved sealing and structural stability: The rotational molding process eliminates weld seams in the cabin, fundamentally solving the leakage problem caused by joints in traditional processes. Combined with a precisely designed sealing groove and insert fusion structure, the overall leakage rate of the cabin is ≤2.0% / min under a rated pressure of 50kPa, making it fully adaptable to low-pressure conditions. The reinforcing ribs and local thickening design greatly improve the rigidity of the cabin structure, enabling it to stably withstand pressure cycles of 0-50kPa. The wall thickness uniformity deviation is small, avoiding deformation cracking caused by stress concentration.

[0021] Highly adaptable materials, meeting safety and hygiene standards: Rotational molding grade composite plastics (polyethylene, etc.) combine weather resistance, impact resistance, chemical stability, and biological safety, with a temperature range covering -40℃ to 90℃, adaptable to different usage environments; the material releases no harmful substances, passes chemical compatibility testing, and the inner wall of the chamber is smooth without burrs or unsanitary corners, facilitating cleaning and disinfection, meeting the hygiene requirements of the medical and health care field, and the addition of flame retardants and UV stabilizers further enhances safety.

[0022] Increased production efficiency and reduced manufacturing costs: Rotational molding is a one-time molding process that eliminates the need for subsequent splicing, welding, and anti-corrosion treatment, shortening the production cycle by more than 50% compared to traditional processes; mold investment is lower than that of injection molding, and the cost of rotational molding grade plastics is lower than that of metals, fiberglass, and special engineering plastics, while the material utilization rate is increased to more than 97%, significantly reducing cabin production energy consumption and manufacturing costs by 50%, facilitating large-scale mass production, and directly promoting the home-based and widespread application of micro-pressure manned (oxygen) cabins.

[0023] Wide adaptability and convenient assembly: Single-person, double-person and multi-person cabins can be customized according to needs to meet the needs of different scenarios; mounting holes and sealing grooves can be reserved in advance, and the cabin door, observation window, pipeline and other components can be assembled without secondary processing, simplifying the overall assembly process of micro-pressure manned (oxygen) cabins. At the same time, the cabin weight is reduced by 50% compared with metal cabins, making it easy to move and install.

[0024] Enhanced safety: Composite plastics are stretchable and flexible, so in the event of an explosion, they will only tear open and leak gas and pressure, without any flying fragments that could injure people.

[0025] The chamber of this invention meets the requirements of "QB / T 8049-2024 Household and Similar Use Micro-Pressure Oxygen Enrichment Chamber". Detailed Implementation

[0026] The present invention will be further described in detail below with reference to specific embodiments:

[0027] This invention discloses a method for manufacturing a micro-pressure manned (oxygen) cabin body using a rotational molding process in a single step. The cabin body is a hollow structure formed in one step using a rotational molding process. The main material is a rotational molding grade (polyethylene, etc.) composite plastic, which has excellent impact resistance, environmental stress cracking resistance, and processing fluidity. The wall thickness of the cabin body is designed to be 3–10 mm, and uniform wall thickness is ensured by precisely controlling the powder usage and rotation speed during the rotational molding process.

[0028] To further enhance the structural strength and deformation resistance of the cabin, multiple annular reinforcing ribs and multiple longitudinal reinforcing ribs evenly distributed along the axial direction are integrally formed on the side walls of the main body of the cabin. Radial reinforcing ribs are formed at the top and bottom of the cabin, respectively. These reinforcing ribs are made of the same material as the main body of the cabin and are integrally rotomolded, forming a seamless whole, which effectively enhances the structural stability of the cabin under pressure.

[0029] A hatch for personnel to enter and exit is located on the side of the main body of the cabin. The hatch door frame and the cabin body are formed by rotational molding in one piece. The edge of the hatch door frame is provided with a sealing groove, and a silicone elastic sealing strip is embedded in the sealing groove. When the hatch is closed, the elastic sealing strip is fully compressed by pressing the hatch door panel against the hatch door frame, so as to achieve a reliable seal.

[0030] The main body of the cabin is equipped with an air inlet and an exhaust outlet, which are connected to the main body of the cabin via connectors to ensure that gas does not leak. The air inlet is used to connect to an external air source system, while the exhaust outlet is connected to a pressure regulating valve to control the pressure inside the cabin.

[0031] Furthermore, the inner wall of the main body of the cabin is naturally smooth after rotational molding, requiring no additional polishing and facilitating daily cleaning and disinfection. Depending on actual needs, pressure sensor interfaces, lighting system interfaces, and observation windows can also be pre-installed on the cabin and sealed accordingly. Example 1:

[0032] Mold preparation: Make a rotational molding mold that matches the shape of the main body of the cabin (including reinforcing ribs, installation positions of each interface and cabin door frame). The mold material can be cast aluminum or steel.

[0033] Raw material preparation: Add a certain amount of rotational molding grade (polyethylene, etc.) composite plastic powder into the main body mold of the cabin.

[0034] Rotational molding: Install the mold on the rotational molding machine, close the mold, set the rotational speed of the rotational molding machine (e.g., 10-15 rpm for the main shaft and 8-12 rpm for the auxiliary shaft) and the heating temperature (e.g., 200-250℃) and heating time, so that the mold rotates and is heated in the heating furnace, and the plastic powder gradually melts and adheres evenly to the inner wall of the mold.

[0035] Cooling and demolding: After heating is complete, move the mold to the cooling station, continue to rotate and blow in cold air or spray water to cool it. After the mold and the product have cooled down sufficiently, open the mold and take out the formed cabin body.

[0036] Post-processing and assembly: Necessary trimming and deburring are performed on the main body of the cabin and the door frame. Then, the hatch, elastic sealing strips, observation windows, air intake, exhaust and other components are installed, and an airtightness test is conducted. Example 2:

[0037] Cabin Manufacturing: Modified high-density polyethylene (HDPE) is selected as the rotational molding raw material, with the addition of 0.5% antioxidant 1010, 0.3% UV absorber UV-531, and 10% flame retardant decabromodiphenyl ether (or other environmentally friendly flame retardants). A mold with longitudinal and transverse grid-like reinforcing ribs is designed, with the ribs being 30 mm high and 20 mm wide. A fixed amount of modified HDPE raw material is added to the mold, and the mold is closed. The mold rotates on a rotational molding machine along two mutually perpendicular axes at speeds of 5 rpm for the main shaft and 8 rpm for the secondary shaft. Simultaneously, the mold is heated using hot air at a temperature of 200-250 degrees Celsius for 30-40 minutes, allowing the plastic raw material to melt, flow, and evenly cover the inner surface of the mold and the reinforcing rib structure. Heating is then stopped, and the mold continues to rotate while cooling water is circulated for 20-30 minutes. After cooling, open the mold and remove the one-piece molded cabin blank. Perform necessary post-processing on the cabin blank, such as removing burrs and polishing.

[0038] Cabin Structure: The cabin is generally horizontally cylindrical or elliptical, approximately 2000 mm in length and 800 mm in diameter, with a wall thickness of 3-10 mm. Internal mesh-like reinforcing ribs are integrally molded with the cabin. A circular door frame is located at one end of the cabin, formed in a single rotational molding process. A sealing groove is machined on the inner side of the door frame. Pre-installed interfaces on the sides of the cabin include an air source inlet, a pressure sensor interface, and a pressure relief valve interface; these interfaces are also integrally molded with the cabin. Four support legs are integrally molded at the bottom of the cabin. Example 3:

[0039] Preparation of rotational molding powder: 100 kg of LLDPE (melt flow rate of 4.8 g / 10 min), 2.2 kg of nano silica, 3.8 kg of ammonium polyphosphate / pentaerythritol compound flame retardant, 0.48 kg of antioxidant Irganox 1010, 0.32 kg of modifier Irgafos 168, and 0.35 kg of Tinuvin 770 are mixed at high speed for 15 minutes.

[0040] A two-part split alloy mold is used, with the inner cavity dimensions being 1950 mm in length and 780 mm in diameter.

[0041] Rotational molding parameters: spindle speed is 13 rpm, counterspindle speed is 4.2 rpm; heat to 285 degrees Celsius and hold for 25 minutes; cooling process is natural air cooling to 120 degrees Celsius (takes 42 minutes), then forced air cooling to 50 degrees Celsius (takes 28 minutes).

[0042] After demolding, a one-piece molded chamber is obtained. The average wall thickness of the chamber is 8.3 mm (with an error range of ±0.4 mm). The inner surface is provided with axial reinforcing ribs with a height of 10 mm, the bottom is provided with drainage holes with a filter screen and a diameter of 20 mm, and the outer surface is provided with anti-slip stripes.

[0043] A transparent polycarbonate (PC) plate is embedded in the observation window mounting hole on the side wall with a diameter of 200 mm using a hot-melt process to form an edge seal. Testing showed that the chamber maintained pressure at 50 kPa gauge pressure for 24 hours, with a gas leakage rate of 0.41% / hour, an oxygen index of 29.5%, and a simply supported beam impact strength of 70 kJ / m², meeting the requirements of YY / T 1795-2021 "General Technical Conditions for Micro-compression Oxygen Chambers". Example 4:

[0044] Material Preparation: A modified HDPE composite material was prepared according to the following weight ratios: 90 parts of PE100 grade HDPE resin, 0.5 parts of HALS light stabilizer, 2 parts of flame retardant, 5 parts of nano-calcium carbonate reinforcing filler, and 2.5 parts of carbon black UV stabilizer. The above raw materials were added to a high-speed mixer and mixed at 120 degrees Celsius for 15 minutes at a stirring speed of 800 rpm. After uniform mixing, the mixture was cooled to room temperature to obtain a uniformly sized composite powder for rotational molding.

[0045] Mold preparation: Select a single-person cabin mold made of cast aluminum. The inner surface of the mold is polished to ensure that the roughness Ra is less than or equal to 0.8 micrometers. Apply a high-temperature resistant silicone-based release agent evenly to the inner wall of the mold, with the coating thickness controlled at 0.15 mm. Let it air dry for 2 hours before use.

[0046] Multi-stage feeding: The prepared composite powder is fed into the mold in stages according to the ratio of 30% for the bottom layer, 50% for the middle layer, and 20% for the top layer. The bottom layer powder contains all the carbon black UV stabilizer to ensure the weather resistance of the outer shell. After each feeding, the mold is closed and the sealing performance of the mold is checked to prevent material leakage during the molding process.

[0047] Rotational molding: The closed mold is fixed on the rotational molding machine. The main shaft speed is set to 6 rpm, the auxiliary shaft speed is set to 3 rpm, the heating temperature is set to 240 degrees Celsius, and the temperature is maintained for 45 minutes to allow the composite powder to fully melt and adhere evenly to the inner wall of the mold, forming an integrated structure.

[0048] Segmented cooling: After heating is completed, the air cooling system is turned on to cool the mold. When the mold temperature drops to 75 degrees Celsius, the water cooling system is switched to continue cooling until the mold and chamber temperature drop to room temperature (25°C) to prevent deformation or residual stress in the chamber due to rapid cooling.

[0049] Post-demolding processing: Open the mold, remove the main body of the cabin, use special tools to trim the rough edges of the cabin and grind them until there are no sharp edges; use an ultrasonic thickness gauge to test the wall thickness of the cabin, the average wall thickness is 10mm, the wall thickness of the bottom and interface installation position is also 10mm, the wall thickness deviation is ≤4%, which meets the design specifications; clean and grind the inner wall of the cabin as well as the reserved installation holes and sealing grooves to ensure that the inner wall is smooth and free of impurities, and the roughness Ra of the sealing groove wall is ≤1.6μm.

[0050] Performance testing: A sealing test was conducted on the molded cabin. After sealing the cabin, it was filled with gas at a pressure of 50 kPa and left to stand for 1 hour. The leakage rate was measured to be 3.2% / h, which meets the usage requirements. The grounding resistance value was measured to be 3.5Ω, which meets electrical safety standards. At the same time, the impact resistance and temperature resistance of the cabin were tested, and both met the design indicators of the modified material. It can be used for the assembly of single-person micro-pressure manned (oxygen) cabins.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A micro-pressure manned (oxygen) cabin body formed in one step based on a rotational molding process, characterized in that: The cabin body is a hollow closable structure formed by one-step molding through the rotational molding process; the main material of the cabin body is rotational molding grade composite plastic (polyethylene, etc.); the wall thickness of the cabin body is 3-10 mm, and the wall thickness is uniform, and the inner wall surface is smooth; the cabin body is provided with a reinforcing rib structure distributed along the circumferential direction and / or the axial direction inside or outside the cabin body, and the reinforcing rib structure is integrally formed with the cabin body main body through the rotational molding process; the cabin body is provided with an integrally formed cabin body door frame, and the joint part of the cabin body door frame and the cabin door plate is provided with a sealing structure; the cabin body is also provided with an air inlet interface, an air outlet interface and an observation window mounting hole, and the air inlet interface, the air outlet interface and the observation window mounting hole are connected with the cabin body through sealing connectors and ensure air tightness.

2. The micro-pressure manned (oxygen) cabin cabin body according to claim 1, characterized in that: The rotational molding grade composite plastic (polyethylene, etc.) is linear low density polyethylene or cross-linked polyethylene, etc., and can add antioxidants, ultraviolet absorbers and / or flame retardants.

3. The micro-pressure manned (oxygen) cabin cabin body according to claim 1, characterized in that: The wall thickness of the cabin body is 3-10 mm, and the wall thickness is uniform.

4. The micro-pressure manned (oxygen) cabin cabin body according to claim 1, characterized in that: The reinforcing rib structure includes annular reinforcing ribs and / or longitudinal reinforcing ribs arranged on the side walls of the cabin body, and radial reinforcing ribs or grid reinforcing ribs arranged on the top and bottom of the cabin body.

5. The micro-pressure manned (oxygen) cabin cabin body according to claim 1, characterized in that: The cabin body door frame and the cabin body main body are made of rotational molding grade plastic by one-step molding.

6. The micro-pressure manned (oxygen) cabin cabin body according to claim 1, characterized in that: The sealing structure includes a sealing groove arranged on the cabin body door frame or the cabin door plate, and an elastic sealing rubber strip embedded in the sealing groove, and the elastic sealing rubber strip is made of silicone or rubber.

7. The micro-pressure manned (oxygen) cabin cabin body according to claim 1, characterized in that: The inner wall surface of the cabin body is smooth.

8. The micro-pressure manned (oxygen) cabin cabin body according to claim 1, characterized in that: The cabin body is also integrated with a pressure sensor interface, a temperature sensor interface, a lighting system interface, a communication interface or an observation window mounting hole, and these interfaces are sealed.