A PUR in-mold free spray high pressure mixing head and method of use thereof

Abstract

This invention discloses an in-mold high-pressure mixing head for PUR (Polyurethane Rubber) without spraying and its usage method, relating to the field of plastic molding. It includes a first feeding channel, a second feeding channel, a first circuit channel, a second circuit channel, and a mixing chamber; it also includes a nozzle for insertion into the mold, with the mixing chamber and nozzle connected via a discharge channel; it further includes a first piston, a second piston, and a third piston; the first piston moves within the discharge channel; the second piston moves within the mixing chamber; it also includes a suction chamber connected to the discharge channel and / or the mixing chamber, and a suction channel connected to the suction chamber; the third piston moves within the suction channel and is used to open and close the suction channel. This invention provides an in-mold high-pressure mixing head for PUR without spraying and its usage method to solve the problems of high scrap rate and low yield rate in existing in-mold coating-free processes, thereby achieving the goal of improving product yield and reducing production costs.

Description

Technical Field

[0001] This invention relates to the field of plastic molding, specifically to a PUR in-mold spray-free high-pressure mixing head and its usage method. Background Technology

[0002] PUR (Polyurethane) is a class of polymer materials with diverse properties and wide applications. The conventional production process is to use a high-pressure mixing head to directly mix component A (white component, such as polyether) and component B (black component, such as polyisocyanate) under high pressure inside the mixing head.

[0003] In-mold coating (IMC) is an advanced manufacturing technology that integrates product molding and surface decoration. Its core idea is to simultaneously apply color or pattern decoration during injection molding or compression molding, eliminating the need for traditional secondary processing such as painting or electroplating. IMC has been increasingly applied to decorative plastics, such as automotive interior and exterior trim (e.g., A / B pillars, bumpers, grilles), consumer electronics (phone cases, phone back panels, laptop casings), and appliance panels.

[0004] However, in the existing technology, the high gas content inside the raw materials and molds results in a consistently high scrap rate and high production costs, which seriously restricts the widespread application of in-mold paint-free technology in the field of decorative plastics. Summary of the Invention

[0005] This invention provides a PUR in-mold spray-free high-pressure mixing head and its usage method to solve the problems of high scrap rate and low yield rate of products in the existing in-mold spray-free process, thereby achieving the goal of improving product yield and reducing production costs.

[0006] This invention is achieved through the following technical solution:

[0007] A PUR in-mold spray-free high-pressure mixing head includes a first feed channel, a second feed channel, a first circuit channel, a second circuit channel, and a mixing chamber; it also includes a nozzle for insertion into the mold, the mixing chamber and the nozzle being connected through a discharge channel; and it further includes a first piston, a second piston, and a third piston.

[0008] The first piston moves within the discharge channel;

[0009] The second piston moves within the mixing chamber;

[0010] It also includes an air extraction chamber connected to the discharge channel and / or mixing chamber, and an air extraction channel connected to the air extraction chamber. The third piston moves within the air extraction chamber and is used to open and close the air extraction channel.

[0011] In response to the problems of high scrap rate and low yield of products in the in-mold spray-free process in the existing technology, the inventor team of this case found in the process of extensive research that the core reason is that the gas content in the raw materials and inside the mold is too high. Since the polyurethane reactive injection molding process is extremely sensitive to gas, the air remaining in the raw materials and mold may cause obvious defects on the surface and inside after the product is formed, which will seriously affect the product quality.

[0012] To overcome the aforementioned technical problems, this application first proposes an in-mold spray-free high-pressure mixing head for PUR (Polyurethane Reactive Injection Molding). The first feed channel, second feed channel, first loop channel, second loop channel, and mixing chamber are all existing technologies for high-pressure mixing heads used in polyurethane reactive injection molding, and will not be elaborated upon here. The nozzle on the mixing head of this application matches the mold to be processed and is inserted into the mold to achieve in-mold casting. Unlike existing mixing heads with only two pistons, the mixing head of this application includes three pistons. The first piston moves within the discharge channel to open and close the discharge channel and clean it after operation. The second piston moves within the mixing chamber to open and close the mixing chamber and clean it after operation. The mixing head of this application includes a vacuum chamber and a vacuum channel. The vacuum channel is used to connect to an external vacuum generator, and the third piston moves within the vacuum chamber to open and close the vacuum channel.

[0013] Before in-mold casting, the mixing head of this application first moves the third piston to open the evacuation chamber, so that the evacuation chamber, evacuation channel and discharge channel are all connected. The vacuum generator evacuates the air until the air pressure inside the mold reaches the set vacuum level, so that the mold can reach the required vacuum or negative pressure state before operation, which significantly reduces the amount of residual air inside the mold, thereby improving product quality and reducing scrap rate.

[0014] It should be noted that the traditional approach to in-mold vacuum injection molding technology involves installing vacuum equipment connected to the cavity on the mold, requiring modifications to the mold structure and demanding high sealing standards. Furthermore, experiments conducted by the applicant in this case have shown that, due to the unique properties of polyurethane reactive injection molding materials, adding vacuum equipment to the mold easily leads to blockage of the corresponding vacuum valves and other components by the raw material. This results in the equipment failing after only one or a few uses, making it unsuitable for industrial-scale, mass production. Therefore, this application creatively improves the mixing head, enabling vacuuming of the mold interior without affecting its inherent function. Compared to the traditional approach to vacuum injection molding, this application requires no modifications to the mold structure, eliminates additional sealing requirements, and allows for continuous, uninterrupted mass production, truly realizing the industrial-scale, mass application of PUR in-mold coating-free technology.

[0015] The first piston, second piston, and third piston in this application are each equipped with a corresponding piston cylinder and a power source; hydraulic, pneumatic, or electric power sources can be used.

[0016] Furthermore, the vacuum chamber and the mixing chamber are distributed on opposite sides of the discharge channel, and the axes of the vacuum chamber and the mixing chamber are collinear and perpendicular to the axis of the discharge channel. This design avoids interference between vacuuming operations and normal circulation or mixing and casting operations.

[0017] Furthermore, a pressure monitoring device for monitoring the internal air pressure of the mold is provided on the nozzle end face, and an installation groove is provided on the outer wall of the nozzle, with a sealing ring installed in the installation groove.

[0018] This solution directly monitors the internal pressure of the mold via the mixing head, eliminating the need for additional pressure sensors or other equipment on the mold. This avoids mold modifications and the risks of clogging and damage associated with adding equipment to the mold, thus significantly reducing production costs. The pressure monitoring device can monitor the vacuum state inside the mold in real time before injection and also monitor the dynamic pressure changes inside the mold during injection, ensuring the accuracy and reliability of the monitoring data. This helps maintain a high product yield and significantly reduces operating and equipment maintenance costs. A sealing ring is used to seal the nozzle and mold, and can be selected adaptably according to specific working conditions.

[0019] Furthermore, the inner wall of the mixing chamber is provided with two relatively distributed discharge ports, which are respectively used to communicate with the first feed channel and the second feed channel; the discharge direction of the two discharge ports is inclined away from the direction of the discharge channel.

[0020] In this design, during the mixing process, the second piston is positioned on the side of the two discharge ports furthest from the discharge channel. Materials A and B are ejected at an angle from the two discharge ports towards the second piston. The two high-pressure materials first collide violently within the mixing chamber, undergoing the first mixing. Then, the mixed materials impact the end face of the second piston, undergoing a second mixing. This two-stage mixing significantly enhances the material mixing effect, thereby ensuring the quality of the reaction injection molding and improving the product yield.

[0021] Furthermore, the end face of the second piston is arc-shaped, with the concave surface of the arc facing the direction of the discharge channel; the two discharge ports are located at the two ends of the arc, respectively.

[0022] In this design, two raw materials are sprayed from both ends of the arc towards the middle of the arc. After collision and mixing, the raw materials collide and hit the middle area of ​​the concave surface of the arc. Then, they move rapidly to both sides of the arc and turn towards the discharge channel. During this process, the raw materials can form vortices in the mixing chamber and undergo a third mixing through the vortices, which further enhances the mixing effect of the raw materials and is more conducive to improving the product yield.

[0023] Furthermore, both the first and second feed channels are equipped with filter components and temperature and pressure monitoring components, with the temperature and pressure monitoring components located downstream of the filter components.

[0024] In existing polyurethane production processes, filtration devices are typically installed on the pipeline between the material tank and the mixing head. This pipeline is generally 6-10 meters long and includes some flexible tubing. Microcrystalline particles may adhere to the inner wall of the pipeline, severely interfering with product quality. In particular, the in-mold coating-free process for PUR materials involves low-flow, high-pressure mixing and casting, requiring relatively low flow rates. Residual microparticles in the raw materials can easily cause pressure fluctuations and blockage of the mixing needle valve, leading to a high equipment failure rate, reduced stability, and severely impacting the continuity of production. To overcome these problems, this application incorporates filtration components in both the first and second feed channels within the mixing head, performing an additional filtration of the two raw materials before mixing. This significantly improves the filtration accuracy of the raw materials, making it particularly suitable for the in-mold coating-free process of PUR.

[0025] Furthermore, due to the extremely high gas sensitivity of the in-mold coating process for PUR materials, residual gases in the raw materials can cause obvious defects on the product surface, thus seriously affecting product quality. The filter component in this application, due to its extremely high filtration precision, not only filters the material but also further disperses and refines residual bubbles in the raw materials before mixing. Because the filter component is located inside the mixing head and is very close to the mixing chamber, the dispersed and refined microbubbles do not have sufficient travel time to recombine into larger bubbles. Therefore, this application, through the installation of the filter component, can further reduce the interference of bubbles in the raw materials on product quality and further reduce the scrap rate.

[0026] Furthermore, the temperature and pressure monitoring component in this solution is used to monitor the temperature and pressure of the two raw material components in real time before mixing. This overcomes the problem in existing technologies where temperature and pressure monitoring can only be performed upstream of the mixing head, resulting in unknown temperature and pressure during final mixing and difficulty in ensuring that the raw materials are mixed under optimal performance conditions. This solution is more suitable for in-mold spray-free coating processes of PUR materials, which have high requirements for the temperature and pressure of the raw materials. The temperature and pressure monitoring component can be implemented using any existing method for monitoring temperature and pressure, and no specific limitations are made here.

[0027] Furthermore, the filter assembly includes a connector connected to a first feed channel or a second feed channel, a cover detachably connected to the connector, and a hollow filter element located inside the cover, wherein there is an annular space between the hollow filter element and the cover; the connector includes an inlet channel and an outlet channel, wherein the inlet channel communicates with the annular space, and the outlet channel communicates with the hollow region inside the hollow filter element.

[0028] Due to the small size of the high-pressure mixing head, the space available for installing the filter assembly is limited. Conventional high-pressure filters are too large to fit this application. To overcome this problem, a filter assembly specifically designed for this application has been developed. This filter assembly is connected to the first or second feed channel via a connector, and is connected to the pipelines at both ends via an inlet flow channel and an outlet flow channel. Fluid enters the connector from the inlet flow channel, then enters the annulus between the cover and the hollow filter element. Under pressure, it permeates from the outside to the inside of the hollow filter element until it passes through the hollow region inside the filter element, and then exits from the outlet flow channel.

[0029] As can be seen, this solution innovatively employs an outside-to-inside flow filtration component in the mixing head, allowing the fluid in the first or second feed channel to be filtered separately. This avoids affecting the overall length of the first or second feed channel, resulting in a compact structure and small footprint. Furthermore, the detachable cover facilitates the replacement or cleaning of the internal hollow filter element. Of course, a good seal must be maintained between the cover and the connector.

[0030] Furthermore, the mixing chamber and the discharge channel are both located inside the housing, and the system also includes a temperature monitoring device for monitoring the temperature of the housing. Additionally, it includes a heating device for heating the housing.

[0031] PUR reactive injection molding is extremely sensitive to raw material temperature. Although the raw material is heated to a set temperature upstream and insulation layers are installed on the relevant pipelines, the temperature inside the mold may not meet the set requirements, thus affecting product quality. The inventors of this project analyzed that this is because the metal mixing head has excellent thermal conductivity. When the ambient temperature is low, the raw material loses some heat during flow and mixing within the mixing head, causing a drop in temperature, either overall or locally. This results in uneven temperature distribution of the raw material entering the mold, affecting product quality. To overcome this problem, this solution monitors and heats the shell of the mixing head. At least the mixing chamber and discharge channel are located inside the shell. Therefore, by maintaining the stability of the shell temperature, heat exchange between the internal raw material and the external environment is reduced, ensuring that the raw material enters the mold at a stable and uniform temperature, thereby improving product quality and increasing yield.

[0032] The method of using the PUR in-mold spray-free high-pressure mixing head based on this application includes the following steps:

[0033] S1. Insert the nozzle into the mold to seal the mold and the contact area between the mold and the nozzle;

[0034] S2. Retract the first piston to connect the suction chamber to the discharge channel; extend the second piston to close the mixing chamber; retract the third piston to connect the suction chamber to the suction channel.

[0035] S3. Vacuum is drawn from the evacuation channel using a vacuum generator until the internal pressure of the mold reaches the set vacuum level, and then the vacuum generator is turned off. During this period, material A is circulated through the first feeding channel and the first circuit channel, and material B is circulated through the second feeding channel and the second circuit channel.

[0036] S4. Extend the third piston to close the suction chamber; retract the second piston to open the mixing chamber.

[0037] S5. Material A and material B enter the mixing chamber from the first feeding channel and the second feeding channel, respectively. The mixed materials pass through the mixing chamber, the discharge channel and the nozzle in sequence and are injected into the mold.

[0038] This method can simultaneously extract air from the mixing head while creating a vacuum inside the mold, thereby improving product yield and reducing production costs.

[0039] Compared with the prior art, the present invention has at least the following advantages and beneficial effects:

[0040] 1. This invention discloses an in-mold high-pressure mixing head for PUR without spraying and its usage method. The mixing head enables vacuuming of the mold interior without affecting its inherent function. This application requires no modification to the mold structure or additional sealing requirements, and enables continuous, uninterrupted mass production, truly realizing the industrialization and mass application of PUR in-mold high-pressure technology without spraying.

[0041] 2. The present invention provides a PUR in-mold spray-free high-pressure mixing head and its usage method. The two-component raw materials undergo three mixing processes in sequence inside the mixing chamber, which enhances the mixing effect of the raw materials and is more conducive to improving the product yield.

[0042] 3. The present invention provides a PUR in-mold spray-free high-pressure mixing head and its usage method. Before mixing, the raw materials are filtered through a filter component in the mixing head, which significantly improves the filtration accuracy of the raw materials and is particularly suitable for the use of PUR in-mold spray-free processes. It can also reduce the interference of air bubbles in the raw materials on product quality and further improve the product yield.

[0043] 4. This invention discloses an in-mold, spray-free high-pressure mixing head for PUR and its usage method. It employs a filter assembly with outward-to-inward flow, allowing fluid from the first or second feed channel to be filtered separately. This avoids affecting the overall length of the first or second feed channel, resulting in a compact structure and small footprint. Furthermore, it facilitates the replacement or cleaning of the hollow filter element inside the filter assembly.

[0044] 5. The present invention provides a PUR in-mold spray-free high-pressure mixing head and its usage method. The mixing head housing is temperature monitored and heated. At least a mixing chamber and a discharge channel are located inside the housing. Therefore, by maintaining the stability of the housing temperature, the heat exchange between the internal raw materials and the outside is reduced, thereby ensuring that the raw materials enter the mold at a stable and uniform temperature as much as possible, thereby improving product quality and increasing yield. Attached Figure Description

[0045] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0046] Figure 1 This is a schematic diagram of a specific embodiment of the present invention;

[0047] Figure 2 This is a front view of a specific embodiment of the present invention;

[0048] Figure 3 For Figure 2 A partial sectional view of the AA direction line;

[0049] Figure 4 for Figure 3 A magnified view of a section at point C;

[0050] Figure 5 A side view of the second piston in a specific embodiment of the present invention;

[0051] Figure 6 For Figure 2 A cross-sectional view of the BB direction line.

[0052] The attached diagram shows the markings and corresponding component names:

[0053] 101-First feed channel, 102-Second feed channel, 103-First loop channel, 104-Second loop channel, 105-Mixing chamber, 106-Nozzle, 107-Discharge channel, 108-First piston, 109-Second piston, 110-Third piston, 111-Air extraction chamber, 112-Air extraction channel, 113-Pressure monitoring device, 114-Sealing ring, 115-Discharge port, 116-Filter assembly, 1161-Connector, 1162-Cover, 1163-Hollow filter element, 1164-Annular space, 1165-Inlet channel, 1166-Outlet channel, 117-Temperature and pressure monitoring assembly, 118-Housing shell, 119-Temperature monitoring device, 120-Heating device, 121-First piston cylinder, 122-Second piston cylinder, 123-Third piston cylinder. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for explaining the invention only and are not intended to limit the invention. In the description of this application, it should be understood that terms such as "front," "rear," "left," "right," "upper," "lower," "vertical," "horizontal," "high," "low," "inner," and "outer," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application.

[0055] Example 1:

[0056] like Figures 1 to 4 The illustrated PUR in-mold spray-free high-pressure mixing head includes a first feed channel 101, a second feed channel 102, a first circuit channel 103, a second circuit channel 104, and a mixing chamber 105; it also includes a nozzle 106 for insertion into the mold, and the mixing chamber 105 and the nozzle 106 are connected through a discharge channel 107; it also includes a first piston 108, a second piston 109, and a third piston 110;

[0057] The first piston 108 moves within the discharge channel 107;

[0058] The second piston 109 moves within the mixing chamber 105;

[0059] It also includes an air extraction chamber 111 connected to the discharge channel 107 and / or the mixing chamber 105, and an air extraction channel 112 connected to the air extraction chamber 111. The third piston 110 moves within the air extraction chamber 111 and is used to open and close the air extraction channel 112.

[0060] In this embodiment, the suction chamber 111 and the mixing chamber 105 are distributed on opposite sides of the discharge channel 107, and the axes of the suction chamber 111 and the mixing chamber 105 are collinear and perpendicular to the axis of the discharge channel 107.

[0061] In this embodiment, a pressure monitoring device 113 for monitoring the internal air pressure of the mold is also provided on the end face of the nozzle 106, and an installation groove is provided on the outer wall of the nozzle 106, and a sealing ring 114 is provided in the installation groove.

[0062] The inner wall of the mixing chamber 105 is provided with two oppositely distributed discharge ports 115, which are respectively used to communicate with the first feed channel 101 and the second feed channel 102; the discharge direction of the two discharge ports 115 is inclined away from the discharge channel 107.

[0063] like Figure 5 As shown, the end face of the second piston 109 is arc-shaped, with the concave surface of the arc facing the direction of the discharge channel 107; the two discharge ports 115 are located at the two ends of the arc, i.e. Figure 5 The left and right sides of the middle.

[0064] In this embodiment, the first piston 108, the second piston 109 and the third piston 110 each have a corresponding piston cylinder, namely the first piston cylinder 121, the second piston cylinder 122 and the third piston cylinder 123; preferably, all of them are hydraulic cylinders.

[0065] Those skilled in the art should understand that the second piston 109 has two flow channels. When it is necessary to mix raw materials, the second piston 109 retracts, and materials A and B enter the two discharge ports 115 from the two flow channels respectively. When self-circulation is required, the second piston 109 extends, and one flow channel on the second piston 109 connects the first feed channel 101 and the first loop channel 103, and the other flow channel connects the second feed channel 102 and the second loop channel 104.

[0066] Example 2:

[0067] A PUR in-mold spray-free high-pressure mixing head, based on Example 1, such as... Figures 1 to 6 As shown, a filter assembly 116 and a temperature and pressure monitoring assembly 117 are provided on both the first feed channel 101 and the second feed channel 102, and the temperature and pressure monitoring assembly 117 is located downstream of the filter assembly 116.

[0068] The filter assembly 116 includes a connector 1161 connected to a first feed channel 101 or a second feed channel 102, a cover 1162 detachably connected to the connector 1161, and a hollow filter element 1163 located inside the cover 1162, wherein there is an annular space 1164 between the hollow filter element 1163 and the cover 1162; the connector 1161 includes an inlet flow channel 1165 and an outlet flow channel 1166, wherein the inlet flow channel 1165 communicates with the annular space 1164, and the outlet flow channel 1166 communicates with the hollow region inside the hollow filter element 1163.

[0069] The mixing chamber 105 and the discharge channel 107 are both located inside the housing 118, and a temperature monitoring device 119 for monitoring the temperature of the housing 118 is also included. A heating device 120 for heating the housing 118 is also included. In this embodiment, the heating device 120 is an electric heating rod.

[0070] Preferably, there are two heating devices 120, which are symmetrically distributed on both sides of the nozzle 106.

[0071] Preferably, the hollow filter element 1163 uses a filter material with a pore size of less than 1 mm to provide micron-level filtration accuracy.

[0072] Preferably, the axes of the inlet channel 1165 and the outlet channel 1166 are parallel to each other and are both perpendicular to the flow direction of the first feed channel 101 or the second feed channel 102 connected to the connector. The hollow filter element 1163 is cylindrical, and its axis is collinear with the axis of the outlet channel 1166; it has the advantages of compact structure, small space occupation, and easy replacement.

[0073] Example 3:

[0074] The method of using the PUR in-mold spray-free high-pressure mixing head based on Example 1 or 2 includes the following steps:

[0075] S1. Insert the nozzle 106 into the mold to seal the mold and the contact area between the mold and the nozzle 106.

[0076] S2. The first piston 108 is retracted, and the suction chamber 111 is connected to the discharge channel 107; the second piston 109 is extended and the mixing chamber 105 is closed; the third piston 110 is retracted, and the suction chamber 111 is connected to the suction channel 112.

[0077] S3. Vacuum is drawn from the evacuation channel 112 using a vacuum generator until the internal pressure of the mold reaches the set vacuum level, then the vacuum generator is turned off. During this period, material A is self-circulated through the first feed channel 101 and the first circuit channel 103, and material B is self-circulated through the second feed channel 102 and the second circuit channel 104. The vacuum generator can be a vacuum pump, a negative pressure pump, etc.

[0078] S4. Extend the third piston 110 to close the suction chamber 111; retract the second piston 109 to open the mixing chamber 105.

[0079] S5. Material A and material B enter the mixing chamber 105 from the first feeding channel 101 and the second feeding channel 102 respectively. The mixed materials are injected into the mold through the mixing chamber 105, the discharge channel 107 and the nozzle 106 in sequence.

[0080] More preferably, after material A and material B enter the mixing chamber 105 from the first feeding channel 101 and the second feeding channel 102 respectively, material A and material B are ejected obliquely from the two discharge ports 115 toward the direction of the second piston 109. The two high-pressure raw materials first collide violently in the mixing chamber 105 for the first mixing. The mixed raw materials then impact the end face of the second piston 109 for the second mixing. After that, the mixed material moves rapidly along the arc surface of the end face of the second piston 109 and turns toward the discharge channel, forming a vortex in the mixing chamber 105, and is mixed for the third time through the vortex.

[0081] More preferably, step S6 is also included: after the injection is completed, the second piston 109 is extended to close the mixing chamber 105, and the mixing chamber 105 is self-cleaned by the second piston 109. At this time, the two raw materials return to the self-circulation state; the first piston 108 is extended to self-clean the discharge channel 107.

[0082] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific 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.

[0083] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Additionally, the term "connection" as used herein, unless otherwise specified, can refer to a direct connection or an indirect connection via other components.

Claims

1. A PUR in-mold spray-free high-pressure mixing head, comprising a first feed channel (101), a second feed channel (102), a first circuit channel (103), a second circuit channel (104), and a mixing chamber (105); characterized in that, It also includes a nozzle (106) for insertion into the mold, and the mixing chamber (105) and the nozzle (106) are connected through a discharge channel (107); it also includes a first piston (108), a second piston (109) and a third piston (110). The first piston (108) moves within the discharge channel (107); The second piston (109) moves within the mixing chamber (105); It also includes an air extraction chamber (111) communicating with the discharge channel (107) and / or the mixing chamber (105), and an air extraction channel (112) communicating with the air extraction chamber (111). The third piston (110) moves in the air extraction chamber (111), and the third piston (110) is used to open and close the air extraction channel (112).

2. The PUR in-mold spray-free high-pressure mixing head according to claim 1, characterized in that, The suction chamber (111) and the mixing chamber (105) are distributed on opposite sides of the discharge channel (107), and the axes of the suction chamber (111) and the mixing chamber (105) are collinear and perpendicular to the axis of the discharge channel (107).

3. The PUR in-mold spray-free high-pressure mixing head according to claim 1, characterized in that, The nozzle (106) end face is provided with a pressure monitoring device (113) for monitoring the air pressure inside the mold, and the outer wall of the nozzle (106) is also provided with an installation groove, and a sealing ring (114) is provided in the installation groove.

4. The PUR in-mold spray-free high-pressure mixing head according to claim 1, characterized in that, The inner wall of the mixing chamber (105) is provided with two relatively distributed discharge ports (115), which are respectively used to communicate with the first feed channel (101) and the second feed channel (102); the discharge direction of the two discharge ports (115) is inclined away from the discharge channel (107).

5. A PUR in-mold spray-free high-pressure mixing head according to claim 4, characterized in that, The end face of the second piston (109) is arc-shaped, and the concave surface of the arc faces the direction of the discharge channel (107); the two discharge ports (115) are located at the two ends of the arc respectively.

6. The PUR in-mold spray-free high-pressure mixing head according to claim 1, characterized in that, A filter assembly (116) and a temperature and pressure monitoring assembly (117) are provided on both the first feed channel (101) and the second feed channel (102), and the temperature and pressure monitoring assembly (117) is located downstream of the filter assembly (116).

7. A PUR in-mold spray-free high-pressure mixing head according to claim 6, characterized in that, The filter assembly (116) includes a connector (1161) connected to a first feed channel (101) or a second feed channel (102), a cover (1162) detachably connected to the connector (1161), and a hollow filter element (1163) located inside the cover (1162), wherein there is an annular space (1164) between the hollow filter element (1163) and the cover (1162); the connector (1161) includes an inlet channel (1165) and an outlet channel (1166), wherein the inlet channel (1165) communicates with the annular space (1164), and the outlet channel (1166) communicates with the hollow area inside the hollow filter element (1163).

8. The PUR in-mold spray-free high-pressure mixing head according to claim 1, characterized in that, The mixing chamber (105) and the discharge channel (107) are both located inside the housing (118), and a temperature monitoring device (119) for monitoring the temperature of the housing (118) is also included.

9. A PUR in-mold spray-free high-pressure mixing head according to claim 8, characterized in that, It also includes a heating device (120) for heating the housing (118).

10. A method of using the PUR in-mold spray-free high-pressure mixing head according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Insert the nozzle (106) into the mold to seal the mold and the contact area between the mold and the nozzle (106); S2. Retract the first piston (108) to connect the suction chamber (111) with the discharge channel (107); extend the second piston (109) to close the mixing chamber (105); retract the third piston (110) to connect the suction chamber (111) with the suction channel (112); S3. Vacuum is drawn from the vacuum channel (112) by the vacuum generator until the internal pressure of the mold reaches the set vacuum level, and the vacuum generator is turned off. During this period, material A is circulated through the first feed channel (101) and the first loop channel (103), and material B is circulated through the second feed channel (102) and the second loop channel (104). S4. Extend the third piston (110) and close the suction chamber (111); retract the second piston (109) and open the mixing chamber (105). S5. Material A and material B enter the mixing chamber (105) from the first feeding channel (101) and the second feeding channel (102) respectively. The mixed materials pass through the mixing chamber (105), the discharge channel (107) and the nozzle (106) in sequence and are injected into the mold.

Images