Polyurethane sealing element and production process thereof

Abstract

The invention belongs to the technical field of sealing parts, and particularly discloses a polyurethane sealing part and a production process thereof.The polyurethane sealing part comprises a first connecting pipe and a second connecting pipe, and the end, close to the first connecting pipe, of the second connecting pipe is fixedly connected with an inserting ring. The problems that a traditional sealing piece is small in contact area and poor in coating performance are solved, a first connecting pipe and a second connecting pipe are positioned through an inserting ring to form mechanical embedding, a protruding ring of a sealing connecting ring is matched with an annular groove of an elastic ring and an expansion rubber ring to construct a physical sealing barrier, the contact area is increased, and when an extrusion assembly applies pressure, an external supply set injects viscoelastic fluid of an outer bag body into an inner cavity of the elastic ring; the driving elastic ring and the expansion rubber ring are internally expanded and externally hooped to doubly wrap and fill the interface gap, so that the plane-to-three-dimensional contact upgrade is realized, the stress is uniformly dispersed, and the expansion rubber ring can compensate the gap through elastic deformation to improve the sealing performance even if the pipeline is rusted and displaced.

Description

Technical Field

[0001] The present invention relates to the technical field of sealing components, in particular to a polyurethane sealing component and a production process thereof. Background Art

[0002] In the field of pipeline connection technology, seals are key components that ensure safe and stable medium transmission. Their performance directly affects the reliability and service life of the pipeline system. Polyurethane seals are widely used in water supply and drainage, chemical industry, petroleum and other fields due to their high strength, high elasticity, and excellent oil and aging resistance. Although their working principle of filling the gap between pipeline interfaces through elastic deformation can achieve basic sealing functions, existing technologies still have significant limitations.

[0003] The automotive oil seal rubber seal with announcement number "CN217481837U" has improved wear resistance through a composite structural design, but its single annular gasket shape cannot meet the sealing requirements under complex working conditions;

[0004] First, the contact area between this type of seal and the pipeline is limited, and it is impossible to form a full-scale and tight coverage of the interface. Especially when the pipe diameter is irregular or there is a slight processing error in the interface, local inadequate fitting is likely to occur, resulting in residual gaps or holes. Secondly, due to the uneven distribution of contact stress between the seal and the pipeline, in the process of long-term exposure to internal pressure fluctuations, medium corrosion and changes in external environmental temperature and humidity, stress concentration is likely to occur on the contact surface between the seal and the pipeline, accelerating the aging of the seal and the rust of the pipeline. This interaction will cause the originally tiny gap to gradually expand. Even if no leakage occurs in the early stage of use, the sealing performance will drop sharply over time, eventually causing medium leakage, which not only causes waste of resources, but may also cause safety accidents or environmental pollution. In addition, the existing seals lack adaptive adjustment capabilities, making it difficult to dynamically compensate for displacement changes caused by thermal expansion and contraction of the pipeline and mechanical vibration, further weakening the stability and durability of the seal. It can be seen that the overall application of the existing technology has certain defects and shortcomings, so it needs to be improved and designed.

[0005] To this end, we propose a polyurethane seal and its production process to solve the above problems. Summary of the Invention

[0006] The object of the present invention is to provide a polyurethane seal and a production process thereof, so as to solve the problem of poor sealing performance during application of the prior art mentioned in the above background art.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a polyurethane seal, comprising a first connecting tube and a second connecting tube, wherein an end of the second connecting tube close to the first connecting tube is fixedly connected to a splice ring, the splice ring being inserted into the interior of the first connecting tube, a sealing connecting ring being fixedly mounted on the inner ends of the inner sides of the first connecting tube and the splice ring, a composite seal being provided between the inner sides of the sealing connecting rings, an extrusion assembly being fixedly connected to the inner ends of the outer surfaces of the first connecting tube and the second connecting tube, the outer side of the composite seal extending outside the first connecting tube, and the extrusion end of the extrusion assembly being provided on the outer side of the composite seal;

[0008] The composite seal includes an inner sealing group and an outer supply group. The inner sealing group is arranged inside the first connecting tube and between the inner sides of the two sealing connecting rings. The outer supply group is arranged in a ring shape at equal intervals and is arranged on the outer side of the first connecting tube near one end of the second connecting tube. The inner end of the outer supply group passes through the first connecting tube and is connected to the inner sealing group. The outer supply group is arranged on the inner side of the two extrusion components.

[0009] Furthermore, an inner cavity is opened inside the elastic ring, and the inner cavity is filled with filling fluid. The external supply group is arranged in a ring shape with equal intervals and fixedly connected to the outside of the elastic ring. The main part of the external supply group is arranged on the outside of the first connecting tube, and the external supply group is arranged between the inner sides of the two extrusion components.

[0010] Furthermore, the filling fluid is set to be an elastic fluid, the viscous fluid is composed of polyurethane prepolymer, carbon black filler and clay filler, and the elastic ring is made of elastic polyurethane material.

[0011] Furthermore, the fixed arms are arranged in a ring shape at equal intervals and fixedly installed on the inner ends of the first connecting tube and the second connecting tube, and an extrusion ring disk is fixedly installed on the inner side of the fixed arm. The extrusion ring disk is covered on the end of the first connecting tube and the second connecting tube that is close to each other, and the inner side of the extrusion ring disk is fitly connected to the outer supply group.

[0012] Furthermore, expansion rubber rings are fixedly installed on the top inner and outer sides of the elastic ring, and expansion rubber rings are also fixedly connected to the bottom inner and outer sides of the elastic ring. The expansion rubber rings are all made of thermoplastic polyurethane elastomer, and the inner side of the expansion rubber ring is connected to the interior of the inner cavity.

[0013] Furthermore, the external supply group includes a connecting hose, which is arranged in a ring shape with equal intervals and fixedly connected to the outside of the elastic ring. The inner end of the connecting hose is connected to the inner cavity inside the elastic ring. The outer end of the connecting hose is fixedly connected to an outer sac, and the interior of the outer sac is filled with external fluid.

[0014] Furthermore, the external supply group also includes through holes, which are arranged in a ring shape with equal intervals and opened at one end of the first connecting tube close to the second connecting tube. The outer end of the connecting hose passes through the through hole and penetrates the first connecting tube. The external fluid is composed of elastic fluid, and the external fluid is also composed of polyurethane prepolymer, carbon black filler, and clay filler. The outer capsule is composed of thermoplastic polyurethane elastomer.

[0015] Furthermore, the inner side of each of the sealing connection rings is fixedly connected with a raised ring, and the raised ring is inserted between the inner sides of the two expansion rubber rings.

[0016] Furthermore, an annular groove is provided at the bottom of the elastic ring located between the inner sides of the two expansion rubber rings and at the top of the elastic ring located between the two expansion rubber rings, and the raised rings are inserted into the annular grooves.

[0017] In a second aspect, the present invention provides a polyurethane seal and a production process thereof, comprising the following steps:

[0018] Step 1: Raw material pretreatment: Use a high-precision electronic scale to weigh the polyurethane raw materials such as polyester polyol, diisocyanate, and chain extender separately, with the error controlled within ±0.1%. Add carbon black filler and clay filler to a high-speed disperser and disperse them at a speed of 3000 r / min for 30 minutes to evenly mix them into the polyurethane prepolymer raw material to prepare the viscoelastic fluid raw material. The elastic polyurethane raw material and the thermoplastic polyurethane elastomer raw material are stored separately for future use.

[0019] Step 2: Prepolymer preparation: weighed polyester polyol is placed in a reactor equipped with a stirrer and a thermometer, heated to 110°C and vacuum-dehydrated for 2 hours, diisocyanate is added, and the reaction is carried out at 80-90°C for 3-4 hours. The reaction progress is monitored in real time by an infrared spectrometer. When the isocyanate group content reaches the set value, a polyurethane prepolymer is obtained;

[0020] Step 3: Precision machining of molds. Use a five-axis CNC machine tool to process the casting mold according to the seal design drawing. The mold cavity size reserves a 0.5mm shrinkage allowance and the surface roughness is machined to Ra≤0.8μm. For the molding parts of the mold corresponding to the outer capsule, connecting hose, and elastic ring, use an EDM machine tool to open the precision flow channel. First, use computer-aided design (CAD) software to design the flow channel three-dimensional model, and then use computer-aided manufacturing (CAM) software to generate the processing path. Use a copper electrode with a diameter of 0.5-1mm and cut it on the EDM machine. The bed uses a fine discharge method to etch away the mold material, accurately forming a flow channel with a diameter of 1-2mm, ensuring the flow channel size accuracy within ±0.02mm. At the same time, CNC milling is used in the mold part corresponding to the inner cavity. A micro end mill is used to gradually mill the inner cavity shape from the mold surface in a layered milling method. The milling depth of each time is controlled at 0.2-0.3mm, and finally the designed inner cavity size is achieved. After processing, the mold surface is polished to ensure that the inner cavity surface roughness Ra ≤ 1.6μm, ensuring smooth injection of raw materials and easy demoulding.

[0021] Step 4: The elastic ring and the external supply assembly are integrally formed. The thermoplastic polyurethane elastomer granules are added to the hopper of the injection molding machine. After being melted at 200-220°C, they are injected into the mold cavity formed by the elastic ring and the external supply assembly through a precision screw at a pressure of 15-20 MPa. After holding the pressure for 10-15 seconds, the mold is cooled and formed. After demolding, a semi-finished elastic ring with a connecting hose and an outer capsule prototype is obtained.

[0022] Step 5: Processing the inner cavity and fluid channel: Use a laser drilling machine to open a fluid channel connecting the connecting hose on the semi-finished elastic ring, with the aperture accuracy controlled within ±0.05mm. Use a precision boring machine to fine-process the annular groove of the elastic ring, and the groove width error is controlled within ±0.1mm.

[0023] Step 6: Viscoelastic fluid infusion: Add the prepared viscoelastic fluid raw material to the vacuum infusion machine material tank, evacuate to -0.09 MPa to remove bubbles, and inject the fluid into the elastic ring cavity at a rate of 0.5-1 L / min using a metering pump. At the same time, use a pressure sensor to monitor the infusion pressure in real time to ensure that the pressure is stable at 0.3-0.5 MPa. After the infusion is completed, seal the connecting hose port;

[0024] Step 7: Casting of the seal body: Fix the semi-finished elastic ring containing viscoelastic fluid in the assembly mold, inject the prepared polyurethane prepolymer raw material, and use a low-pressure casting machine to cast at a pressure of 0.2-0.3MPa and a speed of 5-8L / min to ensure that the raw material fills the mold cavity and covers the elastic ring, connecting hose and outer bladder;

[0025] Step 8: After overall curing and shaping, the mold is placed in a program-controlled curing oven and heated according to a preset program. First, it is kept at 60°C for 2 hours, then heated to 80°C for curing for 4 hours. During the curing process, the mold temperature is monitored in real time by a thermocouple to ensure that the temperature uniformity error does not exceed ±2°C.

[0026] Step 9: Mechanical finishing and assembly: After curing, the outer surface of the seal is turned using a CNC lathe with a dimensional accuracy of ±0.02mm. The sealing connecting ring, extrusion ring disc and other metal parts are formed using a high-precision stamping machine. An automatic assembly robot is used to assemble the various components with the seal body and tighten them using locating pins and bolts with a torque controlled at 8-10N·m.

[0027] Step 10: Full inspection and packaging. Use a three-dimensional coordinate measuring machine to detect the size of the seals, and use a helium mass spectrometer leak detector to test the sealing. Qualified products are covered with anti-static protective covers and placed in customized foam-lined packaging boxes. Vacuum packaging machines are used to vacuum-pack the outer boxes, and automatic packaging machines are used to cross-pack the outer boxes to complete the packaging of the finished products.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] First, in the present invention, the polyurethane seal overcomes the problems of small contact area and poor coverage of traditional seals through the multi-level structural design of double-tube plug-in, composite seal and extrusion component. The first connecting tube and the second connecting tube are positioned by the plug-in ring to form a stable mechanical interlocking; the raised ring of the sealing connection ring cooperates with the annular groove of the elastic ring and the expansion rubber ring to form a physical sealing barrier, greatly increasing the contact area. When the external supply group applies pressure in the extrusion component, the viscoelastic fluid in the outer sac is injected into the inner cavity of the elastic ring, driving the elastic ring and the expansion rubber ring to expand, achieving "inner expansion and outer hoop" double coverage, and fully filling the gap of the pipeline interface. This structure realizes the upgrade of contact from flat to three-dimensional, evenly dissipates stress, and prevents stress concentration. Even if the pipeline is corroded or displaced, the expansion rubber ring can continue to compensate for the gap through elastic deformation, effectively avoiding leakage problems caused by insufficient fitting and aging, and significantly improving sealing reliability.

[0030] Secondly, in the present invention, in terms of material application, the seal adopts a composite material system with significant advantages. The elastic ring of the inner sealing group is made of elastic polyurethane, which has high elasticity and fatigue resistance and can cope with high-frequency expansion and contraction without deformation; the elastic fluid filled in the inner cavity is composed of polyurethane prepolymer and filler, which can sensitively respond to pressure changes and realize the expansion and rebound of the elastic ring through molecular slippage to form dynamic sealing compensation. The outer sac and expansion rubber ring of the outer supply group are made of thermoplastic polyurethane elastomer, which not only maintains good elasticity in a wide temperature range, but also has self-repairing ability. When under pressure, the elastic fluid causes the seal to fit tightly to the pipeline and uses the elasticity of the material to fill the microscopic gap; the reversible deformation of the expansion rubber ring can adaptively compensate for the thermal expansion and contraction displacement of the pipeline; elastic polyurethane and thermoplastic polyurethane elastomer are resistant to aging and corrosion, and combined with fluid replenishment and material self-repair, they effectively solve the aging and failure problems of traditional seals and extend the service life of seals. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0032] Figure 2 It is a side view structural diagram of the present invention;

[0033] Figure 3 This is a schematic diagram of the overall split state structure of the present invention;

[0034] Figure 4 This is a schematic structural diagram of the composite seal and the first connecting pipe in the present invention in a disassembled state;

[0035] Figure 5 This is a schematic structural diagram of the composite seal and the first connecting pipe in the present invention in a disassembled state;

[0036] Figure 6 This is a schematic diagram of the overall structure of the composite seal in the present invention;

[0037] Figure 7 This is a schematic diagram of the structure of the composite seal in the present invention in a disassembled state;

[0038] Figure 8 Schematic diagram of the internal structure of the elastic ring in the present invention.

[0039] In the figure: 1. First connecting tube; 2. Second connecting tube; 3. Plug-in ring; 4. Sealing connecting ring; 5. Extrusion assembly; 51. Fixed arm; 52. Extrusion ring disc; 6. Composite seal; 61. Inner sealing group; 611. Inner cavity; 612. Filling fluid; 613. Elastic ring; 614. Expansion rubber ring; 615. Annular groove; 62. External supply group; 621. Connecting hose; 622. External sac; 623. External fluid; 624. Through hole; 7. Raised ring. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0041] See also Figures 1-8 In an embodiment of the present invention, a polyurethane seal comprises a first connecting tube 1 and a second connecting tube 2. An end of the second connecting tube 2 close to the first connecting tube 1 is fixedly connected to a plug-in ring 3, which is inserted into the interior of the first connecting tube 1. A sealing connecting ring 4 is fixedly installed on the inner ends of the inner sides of the first connecting tube 1 and the plug-in ring 3. A composite seal 6 is provided between the inner sides of the sealing connecting ring 4. The inner ends of the outer surfaces of the first connecting tube 1 and the second connecting tube 2 are fixedly connected to an extrusion assembly 5. The outer side of the composite seal 6 extends outside the first connecting tube 1, and the extrusion end of the extrusion assembly 5 is provided with the outer side of the composite seal 6.

[0042] The composite seal 6 includes an inner sealing group 61 and an outer supply group 62. The inner sealing group 61 is arranged inside the first connecting tube 1 and between the inner sides of the two sealing connecting rings 4. The outer supply group 62 is arranged in a ring shape with equal intervals and is arranged on the outer side of the first connecting tube 1 near one end of the second connecting tube 2. The inner end of the outer supply group 62 passes through the first connecting tube 1 and is connected with the inner sealing group 61. The outer supply group 62 is arranged on the inner side of the two extrusion components 5. When the polyurethane seal is working during application, the plug-in ring 3 of the second connecting tube 2 is first inserted into the first connecting tube 1 to complete the initial positioning and form a mechanical interlocking basis. At this time, the inner side of the sealing connecting ring 4 is in contact with the composite seal 6, wherein the elastic ring 613 and the expansion rubber ring 614 of the inner sealing group 61 are initially fitted with the sealing connecting ring 4. Subsequently, the extrusion component 5 is driven by external force, and the first connecting The extrusion assembly 5 at the inner end of the outer surface of the tube 1 and the second connecting tube 2 contracts and squeezes inward, compressing the outer sac 622 and the connecting hose 621 of the outer supply group 62. Under the action of pressure, the viscoelastic fluid in the outer sac 622 is injected into the inner cavity 611 of the elastic ring 613 of the inner sealing group 61 through the connecting hose 621, causing the elastic ring 613 to expand and drive the expansion rubber ring 614 to deform together. The expansion rubber ring 614 fits tightly to the inner and outer walls of the sealing connection ring 4 and the raised ring 7, forming a double covering effect of inner expansion and outer hoop, fully filling the tiny gaps or holes at the pipeline interface, realizing the upgrade of contact from plane to three-dimensional, evenly dispersing contact stress, and avoiding stress concentration. Even if the pipeline is subsequently corroded or displaced, the expansion rubber ring 614 can compensate for the gap through continuous elastic deformation, thereby ensuring the reliability and long-term effectiveness of the seal.

[0043] See also Figure 3-Figure 8The inner sealing group 61 includes an elastic ring 613, an inner cavity 611 is opened inside the elastic ring 613, and the inner cavity 611 is filled with a filling fluid 612. The outer supply group 62 is arranged in a ring shape with equal intervals and is fixedly connected to the outer side of the elastic ring 613. The main part of the outer supply group 62 is arranged on the outer side of the first connecting pipe 1, and the outer supply group 62 is arranged between the inner sides of the two extrusion components 5. The filling fluid 612 is set as an elastic fluid, and the viscous fluid is composed of polyurethane prepolymer, carbon black filler and clay filler. The elastic ring 613 is made of elastic polyurethane material. The top inner and outer sides of the elastic ring 613 are fixedly installed with expansion rubber rings 614, and the bottom inner and outer sides of the elastic ring 613 are also fixedly connected with expansion rubber rings 614. The expansion rubber rings 614 are made of thermoplastic polyurethane elastomer. The inner side of the expansion rubber ring 614 is connected to the inner side of the inner cavity 611. During the use of this device, when the extrusion component 5 is forced to shrink inward, the outer supply The outer bladder 622 of group 62 is squeezed, and the elastic fluid composed of polyurethane prepolymer, carbon black filler and clay filler inside is injected into the inner cavity 611 of the elastic ring 613 through the connecting hose 621. The elastic ring 613 made of elastic polyurethane material expands under the action of the fluid pressure in the cavity, pushing the expansion rubber ring 614 connected to it to deform. The expansion rubber ring 614 made of thermoplastic polyurethane elastomer material, with its excellent elasticity and plasticity, closely fits the inner and outer walls of the sealing connection ring 4 and the raised ring 7, forming a double sealing structure of inner expansion and outer hoop. At the same time, the flow of filling fluid 612 under pressure prompts the expansion rubber ring 614 to fully fill the tiny gaps and irregular surfaces at the pipeline interface, and realizes dynamic sealing by utilizing the fluidity of the fluid and the elasticity of the material. Even if the pipeline rusts or shifts due to long-term use, the expansion rubber ring 614 can continue to compensate for the gap through elastic deformation under the pressure support of the elastic fluid, thereby maintaining excellent sealing performance.

[0044] See also Figure 1-Figure 5 and Figure 7-Figure 8The extrusion assembly 5 includes a fixed arm 51, which is arranged in a ring shape at equal intervals and fixedly installed on the inner ends of the first connecting tube 1 and the second connecting tube 2. An extrusion ring disk 52 is fixedly installed on the inner side of the fixed arm 51. The extrusion ring disk 52 is covered on the end of the first connecting tube 1 and the second connecting tube 2 that is close to each other. The inner side of the extrusion ring disk 52 is fitly connected to the outer supply group 62. The outer supply group 62 includes a connecting hose 621, which is arranged in a ring shape at equal intervals and fixedly connected to the outer side of the elastic ring 613. The inner end of the connecting hose 621 is connected to the inner cavity 611 inside the elastic ring 613. The outer end of the connecting hose 621 is fixedly connected to the outer sac 622. The interior of 22 is filled with an external fluid 623, and the external supply group 62 also includes a through hole 624. The through holes 624 are arranged in a ring shape with equal intervals and are opened at one end of the first connecting pipe 1 close to the second connecting pipe 2. The outer end of the connecting hose 621 passes through the through hole 624 and penetrates the first connecting pipe 1. The external fluid 623 is composed of an elastic fluid. The external fluid 623 is also composed of a polyurethane prepolymer and a carbon black filler and a clay filler. The outer capsule 622 is composed of a thermoplastic polyurethane elastomer. The inner side of the sealing connection ring 4 is fixedly connected with a raised ring 7. The raised ring 7 is inserted between the inner sides of the two expansion rubber rings 614. The bottom of the elastic ring 613 is located between the inner sides of the two expansion rubber rings 614. An annular groove 615 is provided between the two expansion rubber rings 614 in the middle and top, and the raised ring 7 is inserted into the inside of the annular groove 615. During the application of this device, when the pipeline is connected, when external force acts on the fixed arm 51 of the extrusion component 5, the extrusion ring disc 52 is driven to move inward, and the inner side of the extrusion ring disc 52 is tightly fitted with the outer sac 622 of the external supply group 62 and pressure is applied. The outer sac 622 is composed of thermoplastic polyurethane elastomer, and the elastic fluid composed of polyurethane prepolymer, carbon black filler and clay filler filled inside passes through the connecting hose 621 under pressure, passes through the first connecting pipe 1 through the through hole 624, and is injected into the inner cavity 611 of the elastic ring 613. The elastic ring 613 made of elastic polyurethane expands under the influence of the fluid pressure in the cavity, driving the top and bottom thermoplastic polyurethane elastomer expansion rubber rings 614 to extend toward the inner walls of the first connecting tube 1 and the second connecting tube 2. It cooperates with the sealing connection ring 4 to further improve the sealing performance. At the same time, the raised ring 7 on the inner side of the sealing connection ring 4 is inserted into the annular groove 615 of the elastic ring 613, and cooperates with the expansion rubber ring 614 to make the expansion rubber ring 614 tightly wrap the pipeline to achieve a double sealing effect and fully fill the pipeline interface gap. Even if the pipeline is displaced or aged, under the pressure of the elastic fluid, the expansion rubber ring 614 can continue to elastically deform to compensate for the gap and maintain sealing reliability.

[0045] A polyurethane seal and a production process thereof, comprising the following steps:

[0046] Step 1: Raw material pretreatment: Use a high-precision electronic scale to weigh the polyurethane raw materials such as polyester polyol, diisocyanate, and chain extender separately, with the error controlled within ±0.1%. Add carbon black filler and clay filler to a high-speed disperser and disperse them at a speed of 3000 r / min for 30 minutes to evenly mix them into the polyurethane prepolymer raw material to prepare the viscoelastic fluid raw material. The elastic polyurethane raw material and the thermoplastic polyurethane elastomer raw material are stored separately for future use.

[0047] Step 2: Prepolymer preparation: weighed polyester polyol is placed in a reactor equipped with a stirrer and a thermometer, heated to 110°C and vacuum-dehydrated for 2 hours, diisocyanate is added, and the reaction is carried out at 80-90°C for 3-4 hours. The reaction progress is monitored in real time by an infrared spectrometer. When the isocyanate group content reaches the set value, a polyurethane prepolymer is obtained;

[0048] Step 3: Precision machining of the mold. Use a five-axis CNC machine tool to process the casting mold according to the seal design drawing. The mold cavity size reserves a 0.5mm shrinkage allowance and the surface roughness is machined to Ra≤0.8μm. For the molding parts of the mold corresponding to the outer capsule 622, the connecting hose 621, and the elastic ring 613, an EDM machine tool is used to open the precision flow channel. First, use the computer-aided design (CAD) software to design the flow channel three-dimensional model, and then use the computer-aided manufacturing (CAM) software to generate the processing path. Use a copper electrode with a diameter of 0.5-1mm and cut it on the EDM machine tool. The mold material is etched away by micro-discharge to precisely form a flow channel with a diameter of 1-2mm, ensuring that the flow channel dimensional accuracy is ±0.02mm. At the same time, CNC milling is used in the mold part corresponding to the inner cavity 611. A micro end mill is used to gradually mill the shape of the inner cavity 611 from the mold surface in a layered milling method. The milling depth of each time is controlled at 0.2-0.3mm, and finally the designed inner cavity 611 size is achieved. After processing, the mold surface is polished to ensure that the surface roughness of the inner cavity 611 is Ra ≤ 1.6μm, ensuring smooth injection of raw materials and easy demoulding.

[0049] Step 4: The elastic ring 613 and the external supply assembly 62 are integrally molded. Thermoplastic polyurethane elastomer granules are added to the hopper of the injection molding machine. After being melted at 200-220°C, they are injected into the molding cavity of the elastic ring 613 and the external supply assembly 62 by a precision screw at a pressure of 15-20 MPa. The pressure is maintained for 10-15 seconds, and then cooled to form the shape. After demolding, the semi-finished elastic ring 613 with the connecting hose 621 and the outer capsule 622 prototype is obtained.

[0050] Step 5: Processing the inner cavity 611 and the fluid channel: Use a laser drilling machine to open a fluid channel connected to the connecting hose 621 on the semi-finished elastic ring 613, with the aperture accuracy controlled within ±0.05mm. Use a precision boring machine to fine-machine the annular groove 615 of the elastic ring 613, with the groove width error controlled within ±0.1mm.

[0051] Step 6: Viscoelastic fluid infusion: Add the prepared viscoelastic fluid raw material to the vacuum infusion machine material tank, evacuate to -0.09 MPa to remove bubbles, and inject the fluid into the inner cavity 611 of the elastic ring 613 at a rate of 0.5-1 L / min using a metering pump. Simultaneously, use a pressure sensor to monitor the infusion pressure in real time to ensure that the pressure is stable at 0.3-0.5 MPa. After the infusion is completed, seal the port of the connecting hose 621;

[0052] Step 7: Casting the seal body: Fix the semi-finished elastic ring 613 containing the viscoelastic fluid in the final assembly mold, inject the prepared polyurethane prepolymer raw material, and use a low-pressure casting machine to cast at a pressure of 0.2-0.3 MPa and a speed of 5-8 L / min to ensure that the raw material fills the mold cavity and covers the elastic ring 613, the connecting hose 621 and the outer bladder 622;

[0053] Step 8: After overall curing and shaping, the mold is placed in a program-controlled curing oven and heated according to a preset program. First, it is kept at 60°C for 2 hours, then heated to 80°C for curing for 4 hours. During the curing process, the mold temperature is monitored in real time by a thermocouple to ensure that the temperature uniformity error does not exceed ±2°C.

[0054] Step 9: Mechanical finishing and assembly. After curing, the outer surface of the seal is turned using a CNC lathe with a dimensional accuracy of ±0.02 mm. The sealing connecting ring 4, extrusion ring disc 52 and other metal components are formed using a high-precision stamping machine. An automatic assembly robot is used to assemble the components with the seal body and tighten them using positioning pins and bolts with a torque controlled at 8-10 N·m.

[0055] Step 10: Full inspection and packaging. Use a three-dimensional coordinate measuring machine to detect the size of the seals, and use a helium mass spectrometer leak detector to test the sealing. Qualified products are covered with anti-static protective covers and placed in customized foam-lined packaging boxes. Vacuum packaging machines are used to vacuum-pack the outer boxes, and automatic packaging machines are used to cross-pack the outer boxes to complete the packaging of the finished products.

[0056] The working principle of this invention is as follows: This polyurethane seal utilizes a multi-layered design with a double-tube plug-in connection, a composite seal 6, and an extrusion assembly 5, effectively addressing the issues of insufficient contact area and poor coverage of conventional seals. The first connecting tube 1 and the second connecting tube 2 are initially positioned by a plug-in ring 3, forming the basis for mechanical engagement. The raised ring 7 on the inner side of the sealing connecting ring 4 inserts into the annular groove 615 of the elastic ring 613, and together with the expansion rubber ring 614, forms a physical seal barrier, significantly increasing the contact area with the pipeline. The connecting hose 621 and the outer bladder 622 of the external supply group 62 are evenly distributed in an annular shape. When the external extrusion component 5 is subjected to an external force, the extrusion ring disk 52 moves inward and squeezes, pressing the outer bladder 622 and the connecting hose 621, and injecting the viscoelastic fluid in the outer bladder 622 into the inner cavity 611 of the elastic ring 613, pushing the elastic ring 613 and the expansion rubber ring 614 to expand synchronously. The expansion rubber ring 614 tightly fits the inner and outer walls of the first connecting pipe 1, the second connecting pipe 2 and the sealing connecting ring 4 through elastic deformation, forming a double covering effect of inner expansion and outer hoop, fully filling the tiny gaps or holes at the interface, realizing the upgrade from single-plane contact to three-dimensional covering, evenly distributing contact stress, avoiding stress concentration, and even if the pipeline is slightly corroded or displaced after long-term operation, the elastic deformation of the expansion rubber ring 614 can continuously compensate for the gap, solving the leakage risk caused by local inadequate fitting and aging of traditional seals;

[0057] During use, the elastic ring 613 of the inner sealing group 61 is made of elastic polyurethane. Its molecular chain structure gives it high elasticity and fatigue resistance, and it can withstand high-frequency expansion and contraction cycles without deformation. The elastic fluid filled in the inner cavity 611 is composed of polyurethane prepolymer and filler. It has both fluidity and elasticity, can quickly respond to pressure changes, and transmits pressure through intermolecular slip to achieve uniform expansion and rebound of the elastic ring 613, forming a dynamic sealing compensation mechanism. The outer bladder 622 and the expansion rubber ring 614 of the external supply group 62 are both made of thermoplastic polyurethane elastomer, which maintains good elasticity over a wide temperature range and has self-healing properties, which can automatically heal minor damage to the sealing surface. Compared with traditional single rubber materials, the composite material system has significant advantages: when the elastic fluid is under pressure, it can transmit pressure through the deformation of the elastic ring 613 and the expansion rubber ring 614, so that the seal fits tightly against the pipe surface and the material's own elasticity is used to fill the microscopic gaps; the expansion rubber ring 614 can cooperate with the deformation to adaptively compensate for the displacement caused by thermal expansion and contraction of the pipe through reversible deformation; elastic polyurethane and TPU have excellent aging resistance and corrosion resistance. Even after long-term use, the sealing performance can be maintained through fluid replenishment and material self-repair, which completely solves the problem of sealing failure caused by aging of traditional seals.

[0058] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0059] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A polyurethane seal, characterized in that: The invention comprises a first connecting tube (1) and a second connecting tube (2), wherein the second connecting tube (2) is fixedly connected to an insert ring (3) at one end close to the first connecting tube (1), and the insert ring (3) is inserted into the interior of the first connecting tube (1); a sealing connecting ring (4) is fixedly installed on the inner ends of the inner sides of the first connecting tube (1) and the insert ring (3); a composite sealing member (6) is provided between the inner sides of the sealing connecting ring (4); an extrusion assembly (5) is fixedly connected to the inner ends of the outer surfaces of the first connecting tube (1) and the second connecting tube (2); the outer side of the composite sealing member (6) extends outside the first connecting tube (1); and the extrusion end of the extrusion assembly (5) is provided on the outer side of the composite sealing member (6); The composite seal (6) comprises an inner seal group (61) and an outer supply group (62); the inner seal group (61) is arranged inside the first connecting tube (1) and between the inner sides of the two sealing connecting rings (4); the outer supply group (62) is arranged in a ring shape at equal intervals and arranged on the outer side of the first connecting tube (1) near one end of the second connecting tube (2); the inner end of the outer supply group (62) passes through the first connecting tube (1) and is connected to the inner seal group (61); and the outer supply group (62) is arranged on the inner sides of the two extrusion assemblies (5).

2. A polyurethane seal according to claim 1, characterized in that: The inner sealing group (61) includes an elastic ring (613), an inner cavity (611) is provided inside the elastic ring (613), and the inner cavity (611) is filled with a filling fluid (612). The outer supply group (62) is arranged in a ring shape at equal intervals and fixedly connected to the outer side of the elastic ring (613). The main part of the outer supply group (62) is arranged on the outer side of the first connecting pipe (1), and the outer supply group (62) is arranged between the inner sides of the two extrusion assemblies (5).

3. A polyurethane seal according to claim 2, characterized in that: The filling fluid (612) is configured as an elastic fluid, the viscous fluid is composed of polyurethane prepolymer, carbon black filler, and clay filler, and the elastic ring (613) is made of elastic polyurethane material.

4. The polyurethane seal according to claim 1, characterized in that: The extrusion assembly (5) comprises fixed arms (51), which are arranged in a ring shape at equal intervals and fixedly mounted on the inner ends of the first connecting tube (1) and the second connecting tube (2). An extrusion ring disc (52) is fixedly mounted on the inner side of the fixed arm (51), and the extrusion ring disc (52) covers one end of the first connecting tube (1) and the second connecting tube (2) that is close to each other. The inner side of the extrusion ring disc (52) is in close contact with the outer supply group (62).

5. The polyurethane seal according to claim 2, characterized in that: An expansion rubber ring (614) is fixedly mounted on the inner and outer sides of the top of the elastic ring (613), and an expansion rubber ring (614) is also fixedly connected to the inner and outer sides of the bottom of the elastic ring (613). The expansion rubber ring (614) is made of thermoplastic polyurethane elastomer, and the inner side of the expansion rubber ring (614) is connected to the interior of the inner cavity (611).

6. The polyurethane seal according to claim 2, characterized in that: The external supply group (62) includes a connecting hose (621), which is arranged in a ring shape at equal intervals and fixedly connected to the outside of the elastic ring (613). The inner end of the connecting hose (621) is connected to the inner cavity (611) inside the elastic ring (613). The outer end of the connecting hose (621) is fixedly connected to the outer sac (622), and the interior of the outer sac (622) is filled with an external fluid (623).

7. A polyurethane seal according to claim 6, characterized in that: The external supply group (62) further comprises through holes (624), which are arranged in a ring shape at equal intervals and are opened at one end of the first connecting tube (1) close to the second connecting tube (2). The outer end of the connecting hose (621) passes through the through hole (624) and penetrates the first connecting tube (1). The external fluid (623) is composed of an elastic fluid, and the external fluid (623) is also composed of a polyurethane prepolymer, a carbon black filler, and a clay filler. The external capsule (622) is composed of a thermoplastic polyurethane elastomer.

8. The polyurethane seal according to claim 5, characterized in that: The inner sides of the sealing connection rings (4) are fixedly connected with raised rings (7), and the raised rings (7) are inserted between the inner sides of the two expansion rubber rings (614).

9. The polyurethane seal according to claim 8, characterized in that: The bottom of the elastic ring (613) is located between the inner sides of the two expansion rubber rings (614) and the top is located between the two expansion rubber rings (614). An annular groove (615) is provided. The raised ring (7) is inserted into the inside of the annular groove (615).

10. A production process for a polyurethane seal, using the polyurethane seal according to any one of claims 1 to 9, characterized in that: The steps include: Step 1: Raw material pretreatment: Use a high-precision electronic scale to weigh the polyurethane raw materials such as polyester polyol, diisocyanate, and chain extender separately, with the error controlled within ±0.1%. Add carbon black filler and clay filler to a high-speed disperser and disperse them at a speed of 3000 r / min for 30 minutes to evenly mix them into the polyurethane prepolymer raw material to prepare the viscoelastic fluid raw material. The elastic polyurethane raw material and the thermoplastic polyurethane elastomer raw material are stored separately for future use. Step 2: Prepolymer preparation: weighed polyester polyol is placed in a reactor equipped with a stirrer and a thermometer, heated to 110°C and vacuum-dehydrated for 2 hours, diisocyanate is added, and the reaction is carried out at 80-90°C for 3-4 hours. The reaction progress is monitored in real time by an infrared spectrometer. When the isocyanate group content reaches the set value, a polyurethane prepolymer is obtained; Step 3: Precision machining of the mold. Use a five-axis CNC machine tool to process the casting mold according to the seal design drawing. The mold cavity size reserves a 0.5mm shrinkage allowance and the surface roughness is machined to Ra≤0.8μm. For the molding parts of the mold corresponding to the outer capsule (622), the connecting hose (621), and the elastic ring (613), an EDM machine tool is used to open the precision flow channel. First, use computer-aided design (CAD) software to design the flow channel three-dimensional model, and then use computer-aided manufacturing (CAM) software to generate the processing path. Use a copper electrode with a diameter of 0.5-1mm and cut it on the EDM machine tool. The mold material is etched away by fine discharge to precisely form a flow channel with a diameter of 1-2 mm, ensuring that the flow channel size accuracy is within ±0.02 mm. At the same time, a CNC milling process is adopted at the mold portion corresponding to the inner cavity (611). A micro end mill is used to gradually mill the shape of the inner cavity (611) from the mold surface by a layered milling method. The milling depth of each time is controlled at 0.2-0.3 mm, and finally the designed inner cavity (611) size is achieved. After the processing is completed, the mold surface is polished to ensure that the surface roughness of the inner cavity (611) Ra is ≤ 1.6 μm, ensuring smooth injection of raw materials and easy demoulding. Step 4: The elastic ring (613) and the external supply assembly (62) are integrally formed. Thermoplastic polyurethane elastomer particles are added to the hopper of the injection molding machine. After being melted at 200-220°C, they are injected into the molding cavity of the elastic ring (613) and the external supply assembly (62) of the mold through a precision screw at a pressure of 15-20 MPa. After holding the pressure for 10-15 seconds, the mold is cooled and formed. After demolding, a semi-finished elastic ring (613) with a connecting hose (621) and an outer capsule (622) is obtained. Step 5: Processing the inner cavity (611) and the fluid channel: a laser punching machine is used to open a fluid channel connected to the connecting hose (621) on the semi-finished elastic ring (613), with the aperture accuracy controlled within ±0.05mm. A precision boring machine is used to fine-process the annular groove (615) of the elastic ring (613), with the groove width error controlled within ±0.1mm. Step 6: Viscoelastic fluid infusion, add the prepared viscoelastic fluid raw material into the vacuum infusion machine material tank, evacuate to -0.09 MPa to eliminate bubbles, and inject the fluid into the inner cavity (611) of the elastic ring (613) at a speed of 0.5-1 L / min through a metering pump. At the same time, use a pressure sensor to monitor the infusion pressure in real time to ensure that the pressure is stable at 0.3-0.5 MPa. After the infusion is completed, seal the connecting hose (621) port; Step 7: Casting the seal body: fix the semi-finished elastic ring (613) containing the viscoelastic fluid in the assembly mold, inject the prepared polyurethane prepolymer raw material, and use a low-pressure casting machine to cast at a pressure of 0.2-0.3 MPa and a speed of 5-8 L / min to ensure that the raw material fills the mold cavity and covers the elastic ring (613), the connecting hose (621) and the outer capsule (622); Step 8: After overall curing and shaping, the mold is placed in a program-controlled curing oven and heated according to a preset program. First, it is kept at 60°C for 2 hours, then heated to 80°C for curing for 4 hours. During the curing process, the mold temperature is monitored in real time by a thermocouple to ensure that the temperature uniformity error does not exceed ±2°C. Step 9: Mechanical finishing and assembly: After curing is completed, the outer surface of the seal is turned using a CNC lathe, and the dimensional accuracy is controlled within ±0.02mm. The metal parts such as the sealing connecting ring (4) and the extrusion ring disk (52) are formed by a high-precision punching machine, and the parts are assembled with the seal body by an automatic assembly robot. The parts are fastened by positioning pins and bolts, and the torque is controlled at 8-10N·m. Step 10: Full inspection and packaging. Use a three-dimensional coordinate measuring machine to detect the size of the seals, and use a helium mass spectrometer leak detector to test the sealing. Qualified products are covered with anti-static protective covers and placed in customized foam-lined packaging boxes. Vacuum packaging machines are used to vacuum-pack the outer boxes, and automatic packaging machines are used to cross-pack the outer boxes to complete the packaging of the finished products.

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