Coating cavity exhaust structure, system and method for in-mold coating process

Abstract

The invention relates to a mold exhaust structure, system and method for an in-mold coating process, and aims to remarkably reduce the phenomena of bubbles and air trapping and improve the appearance quality and functionality of a product by accurately controlling gas exhaust and fluid filling. The exhaust structure comprises a coating cavity, a feeding device, a first flow channel, an exhaust assembly, a second flow channel and a transition flow channel. The circulation sectional area of the second runner is smaller than that of the coating cavity to increase fluid flow resistance; the transition flow channel is designed to be arc-shaped, the included angle formed by the tangent line and the vertical direction of the transition flow channel is gradually increased, and the gas exhaust path is optimized. In addition, the system integrates a man-machine interaction unit, a control unit, a first pressure sensor and a second pressure sensor. And when the detection value of the second pressure sensor is larger than 0 bar, the exhaust assembly is closed, and a pressure maintaining and filling stage is started until coating is completed.

Description

Technical Field

[0001] The present application relates to the technical field of surface treatment of plastic products, and in particular to a coating chamber exhaust system and a control method for an in-mold coating process. Background Art

[0002] In the process of surface treatment of plastic products, in-mold coating technology is widely used because it can complete the coating process of the product directly inside the coating cavity. This technology not only improves production efficiency, but also significantly reduces environmental pollution. However, during the in-mold coating process, if the air inside the coating cavity and the reaction gas that may be generated by the reaction molding coating (such as PUR / PUA polyurethane or polyurea coating) cannot be discharged in a timely and effective manner, it will cause defects such as trapped air and bubbles on the product surface, seriously affecting the appearance quality and functionality of the product.

[0003] Although there are some exhaust measures in the existing in-mold coating technology, due to the lack of an efficient exhaust control system, on the one hand, the coating with good flow properties used in the coating process may hinder the effective exhaust of gas, resulting in bubbles or trapped air inside the product, affecting the quality and appearance of the product; fast-flowing coatings may not be able to fill the cavity evenly, resulting in insufficient or excessive filling of certain parts of the product, affecting the overall performance and consistency of the product. On the other hand, the existing exhaust measures cannot choose the appropriate exhaust time according to the internal pressure of the coating cavity, resulting in poor exhaust effect, which in turn makes the product appearance quality cannot be guaranteed. In addition, the existing exhaust solutions are often only suitable for specific types of coating cavities, with limited scope of application, and cannot meet diversified production needs. Summary of the invention

[0004] In view of one or more problems existing in the prior art, the present application provides, in a first aspect, a coating cavity exhaust structure for an in-mold coating process, comprising a second flow channel, a transition flow channel, a first flow channel and an exhaust assembly, wherein the coating cavity, the second flow channel, the transition flow channel and the first flow channel are connected in sequence.

[0005] Wherein, the flow cross-sectional area of ​​the second flow channel is smaller than the flow cross-sectional area of ​​the coating chamber;

[0006] The transition channel is an arc-shaped channel, and the inclination angle of the transition channel gradually decreases along the flow direction of the fluid;

[0007] The first flow channel includes an inflow end and an outflow end, the inflow end of the first flow channel is connected to the transition flow channel, and the outflow end of the first flow channel is connected to the exhaust component;

[0008] The first flow channel is formed with at least one curved portion for increasing fluid flow resistance.

[0009] The first aspect of the present application provides a coating cavity exhaust structure for an in-mold coating process. By setting a curved portion in the first flow channel, the exhaust of gas is promoted, and defects such as bubbles and trapped air on the product surface caused by gas accumulation are reduced. At the same time, the fluid flow resistance is increased, so that the paint can be filled more evenly in the coating cavity, avoiding the problem of local insufficient filling or excessive filling, and improving the appearance quality and functionality of the product.

[0010] By adding a second flow channel with a smaller flow cross-sectional area, the flow resistance of the fluid is further increased to ensure uniform filling of the fluid in the coating cavity. This is particularly suitable for coatings with excellent fluidity (such as PUR / PUA polyurethane or polyurea coatings), avoiding the problem of local overfilling or underfilling caused by rapid flow.

[0011] At the same time, the smooth transition of the arc-shaped transition channel and the gradually decreasing inclination angle of the transition channel (that is, the angle formed by the tangent of the transition channel and the vertical direction gradually increases) reduce the turbulence and pressure loss of the fluid during turning, making it easier to carry out and discharge the gas, further reducing the occurrence of bubbles or trapped air. At the same time, the fluid flow direction is gradually changed, avoiding unstable flow caused by sudden changes in direction, and improving the stability and consistency of the coating process.

[0012] Preferably, the second flow channel has a height of 0.05 mm to 5 mm and a width of 0.1 mm to 8 mm.

[0013] By setting the height of the second flow channel to 0.05mm to 5mm and the width to 0.1mm to 8mm, the flow resistance of the fluid can be precisely controlled. At the same time, the narrow design of the second flow channel increases the turbulence of the fluid, which helps the gas to separate from the coating and be taken out, thereby improving the gas discharge efficiency and reducing the occurrence of bubbles or trapped air. When the height of the second flow channel is less than 0.05mm or the width is greater than 8mm, the fluid flow resistance will be too large, making it difficult for the coating to pass through the second flow channel, which may cause local overfilling, and increase the risk of the flow channel being blocked by impurities or solidified coating, causing the system to fail to work properly; when the height of the second flow channel is greater than 5mm or the width is less than 0.1mm, the fluid flow resistance will be reduced, allowing the coating to flow quickly into the coating cavity, which may cause local insufficient filling or uneven filling, affecting product quality, and reducing the turbulence of the fluid, which is not conducive to the separation of gas from the coating and being taken out, reducing the gas discharge efficiency, and increasing the risk of bubbles or trapped air.

[0014] Preferably, along the fluid flow direction, the transition channel inclination angle varies in the range of 50° to 1°.

[0015] Preferably, the curved portion is at least one of a U-shaped curved portion, an L-shaped curved portion and an S-shaped curved portion.

[0016] The U-shaped bend, L-shaped bend and S-shaped bend can be selected or used in combination according to actual needs to more accurately adjust the flow resistance of the fluid and ensure uniform filling of the paint in the coating cavity, which is particularly suitable for paints with different viscosities and fluidities.

[0017] Preferably, an overflow well is provided between the curved portion of the first flow channel and the exhaust component, and when the fluid includes paint, the overflow well can receive the paint, thereby preventing the paint in the fluid from entering the exhaust component.

[0018] By adding an overflow well, the excess paint overflowing from the first flow channel can be received to prevent the paint from flowing directly out of the exhaust component and contaminating the mold or affecting the quality of the coating. By receiving the excess paint through the overflow well, the overflow well can protect the exhaust component from being blocked by the paint, ensure its normal operation, and extend the service life of the exhaust component.

[0019] Preferably, the exhaust assembly comprises an exhaust valve and an exhaust valve driver, and the exhaust valve driver is connected to the exhaust valve for controlling the opening and closing of the exhaust valve.

[0020] The exhaust valve driver controls the opening and closing of the exhaust valve, thereby realizing automatic control of the exhaust valve, reducing the need for manual intervention and improving production efficiency.

[0021] A second aspect of the present application provides a coating chamber exhaust system for an in-mold coating process, comprising the coating chamber exhaust structure provided in the first aspect above, and further comprising a human-machine interaction unit, a control unit, a first pressure sensor, and a second pressure sensor;

[0022] The human-computer interaction unit is electrically connected to the control unit and is used for the user to input instruction data information;

[0023] The control unit is electrically connected to the feeding device and is used to control the start and stop of the feeding action of the feeding device;

[0024] The control unit is electrically connected to the exhaust assembly and is used to control the switch of the exhaust assembly;

[0025] The first pressure sensor is arranged on the wall of the coating chamber at the connection with the feeding device, and the first pressure sensor is electrically connected to the control unit, and is used to detect the pressure value in the coating chamber and transmit it to the control unit;

[0026] The second pressure sensor is disposed at the inflow end of the first flow channel. The second pressure sensor is electrically connected to the control unit and is used to detect the pressure value at the inflow end of the first flow channel and transmit it to the control unit.

[0027] The second aspect of the present application provides a coating chamber exhaust system for in-mold coating process, which can not only conveniently input command data information through the human-computer interaction unit to realize automatic control of the system, but also accurately control the opening and closing timing of the exhaust valve, thereby reducing the occurrence of bubbles and trapped air, and improving the appearance quality and functionality of the product. It can also flexibly adjust the feeding speed of the feeding device and the opening and closing time and frequency of the exhaust component according to different coating process requirements, and is suitable for various types of coating chambers and coatings, thereby enhancing the adaptability and flexibility of the system.

[0028] A third aspect of the present application provides a coating chamber exhaust method for an in-mold coating process, the method being performed by the coating chamber exhaust system for the in-mold coating process, the method comprising:

[0029] Presetting the pressure value in the control unit through the human-machine interaction unit;

[0030] The exhaust assembly is opened to connect the coating chamber with the outside world;

[0031] The feeding device conveys the coating material into the coating chamber;

[0032] The first pressure sensor and the second pressure sensor detect pressure values ​​and transmit them to the control unit;

[0033] When the pressure value detected by the second pressure sensor is greater than 0 bar, the control unit controls the exhaust component to close the gas exhaust;

[0034] During the process of the feeding device conveying the coating paint into the coating chamber, the pressure value detected by the first pressure sensor and received by the control unit can reach a preset value.

[0035] The third aspect of the present application provides a coating chamber exhaust method for an in-mold coating process. By setting a preset pressure value, a first pressure sensor monitors the pressure change in the coating chamber in real time, and a second pressure sensor detects the pressure value at the inflow end of the first flow channel. After the pressure in the chamber increases to reach the preset value, the second pressure sensor detects the time point when the pressure value is greater than 0 and closes the exhaust component. After the gas discharge is completed, the pressure is maintained and filled, which reduces the occurrence of bubbles and trapped air and improves the appearance quality and functionality of the product. The entire process is automatically completed by the control system, and the user only needs to input the preset pressure value through the human-computer interaction unit, which reduces the need for manual intervention and improves production efficiency. The control unit can flexibly adjust the feeding speed of the feeding device and the switching time and frequency of the exhaust component according to different coating process requirements. It is suitable for various types of coating chambers and coatings, and enhances the adaptability and flexibility of the system.

[0036] Preferably, the preset pressure value is any value between 20 bar and 120 bar.

[0037] Different preset pressure values ​​can be optimized for different coating viscosity, fluidity and other characteristics to ensure the best coating effect. By setting a reasonable preset pressure value, it can ensure that the gas is discharged at the appropriate time, reduce the occurrence of bubbles and trapped air, and improve the appearance quality and functionality of the product.

[0038] Preferably, the coating temperature is 30° C. to 90° C., and the viscosity is 100 cps to 300 cps.

[0039] The coating chamber exhaust method for the in-mold coating process provided in the present application is suitable for coating materials of different temperatures and viscosities, that is, it can meet the needs of different production processes, has wide applicability and flexibility, and improves production efficiency and economic benefits.

[0040] Preferably, the feeding device conveys the coating material into the coating chamber at a speed of 5 g / min to 700 g / min.

[0041] The conveying speed of 5g / min to 700g / min covers a wide range from very low speed to high speed, which is suitable for different types of coating processes and coating characteristics. By setting a reasonable conveying speed, the uniform distribution of the coating in the coating cavity can be ensured, avoiding the problem of local insufficient filling or excessive filling, and improving the appearance quality and functionality of the product.

[0042] Preferably, when the feeding device conveys the coating paint into the coating chamber, the internal temperature of the coating chamber is 80° C. to 130° C.

[0043] Higher temperatures can accelerate the curing reaction of the coating, shorten the curing time, and improve production efficiency. For some thermosetting coatings, such as polyurethane or polyurea coatings, appropriately increasing the temperature can promote the cross-linking reaction and obtain better coating performance.

[0044] The operating principle of the coating chamber exhaust system for the in-mold coating process provided by this application is as follows:

[0045] Initial state preparation:

[0046] The injection molding machine completes the mold closing operation, and the substrate is fixed inside the mold to form a coating cavity.

[0047] The control unit initializes the system, and the user sets the preset pressure value and other necessary parameters (such as feeding speed) through the human-machine interface unit to ensure that all components are in standby state.

[0048] Open exhaust:

[0049] The control unit controls the exhaust valve drive to open the exhaust valve, allowing the coating chamber to communicate with the outside world so that the air in the coating chamber can be discharged smoothly. At this time, the initial pressure in the coating chamber is about 0 bar.

[0050] Feeding:

[0051] The control unit starts the feeding device to deliver the coating material (such as polyurethane or polyurea coating) to the coating chamber through the mixing head and the feeding channel. At the same time, components such as isocyanate (ISO) and polyol (Poly) are delivered to the mixing head.

[0052] Pressure detection:

[0053] The first pressure sensor monitors the pressure change in the coating chamber in real time, and the second pressure sensor monitors the pressure change at the inflow end of the first flow channel in real time, and transmits these data to the control unit.

[0054] Close the exhaust valve:

[0055] When the pressure value detected by the second pressure sensor is greater than 0 bar, it indicates that the coating material has begun to enter the first flow channel.

[0056] At this time, the control unit will control the exhaust valve drive to close the exhaust valve and stop gas discharge, thus entering the pressure-maintaining filling stage.

[0057] Pressure-holding filling:

[0058] The control unit continues to control the feeding device to convey the paint and perform pressure-maintaining filling until the filling of the coating paint is completed.

[0059] In the above process, the pressure value detected by the first pressure sensor can reach the pressure value preset by the user (such as any value between 20 bar and 120 bar).

[0060] Cooling, solidification and mold opening:

[0061] After filling, the product undergoes a cooling and solidification process in the mold.

[0062] Finally, the injection molding machine performs the mold opening operation and takes out the painted product.

[0063] It should be understood that the technical solutions of various aspects of the present application can be independent of each other or can refer to each other, and the beneficial effects achieved by various aspects and corresponding feasible embodiments can refer to each other and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings:

[0065] Figure 1 It is a structural schematic diagram of a coating chamber exhaust structure for an in-mold coating process provided by an exemplary embodiment of the present application;

[0066] Figure 2 is a structural schematic diagram of a coating chamber exhaust structure for an in-mold coating process provided by another exemplary embodiment of the present application;

[0067] Figure 3 is a structural schematic diagram of a coating chamber exhaust structure for an in-mold coating process provided by another exemplary embodiment of the present application;

[0068] Figure 4 is a structural schematic diagram of a coating chamber exhaust structure for an in-mold coating process provided by yet another exemplary embodiment of the present application;

[0069] Figure 5 It is a structural schematic diagram of a coating chamber exhaust system for an in-mold coating process provided by an exemplary embodiment of the present application;

[0070] Figure 6 is a flow chart of a coating chamber exhaust method for an in-mold coating process provided by an exemplary embodiment of the present application;

[0071] Figure 7 It is a mold cavity pressure variation diagram of a coating cavity exhaust method for an in-mold coating process provided by an exemplary embodiment of the present application;

[0072] Figure 8 This is a product appearance effect diagram of a coating cavity exhaust method for an in-mold coating process provided by an exemplary embodiment of the present application;

[0073] Fig. 9 It is a mold cavity pressure variation diagram of a coating cavity exhaust method for an in-mold coating process provided by an exemplary embodiment of the present application;

[0074] Fig.10 This is a product appearance effect diagram of a coating cavity exhaust method for an in-mold coating process provided by an exemplary embodiment of the present application;

[0075] Fig.11 It is a mold cavity pressure variation diagram of a coating cavity exhaust method for an in-mold coating process provided by an exemplary embodiment of the present application;

[0076] Fig.12 This is a product appearance effect diagram of a coating cavity exhaust method for an in-mold coating process provided by an exemplary embodiment of the present application;

[0077] Fig.13 It is a mold cavity pressure variation diagram of a coating cavity exhaust method for an in-mold coating process provided by an exemplary embodiment of the present application;

[0078] Fig.14This is a product appearance effect diagram of a coating cavity exhaust method for an in-mold coating process provided by an exemplary embodiment of the present application;

[0079] Fig.15 It is a mold cavity pressure variation diagram of a comparative example of a coating cavity exhaust method for an in-mold coating process provided by the present application;

[0080] Fig.16 This is a product appearance effect diagram of a comparative example of the coating chamber exhaust method for the in-mold coating process provided by the present application;

[0081] Fig.17 It is a mold cavity pressure variation diagram of a comparative example of a coating cavity exhaust method for an in-mold coating process provided by the present application;

[0082] Fig.18 This is a product appearance effect diagram of a comparative example of the coating chamber exhaust method for the in-mold coating process provided by the present application;

[0083] Fig.19 It is a mold cavity pressure variation diagram of a comparative example of a coating cavity exhaust method for an in-mold coating process provided by the present application;

[0084] Fig. 20 This is a product appearance effect diagram of a comparative example of the coating chamber exhaust method for the in-mold coating process provided in the present application.

[0085] Reference numerals:

[0086] 1. Coating chamber;

[0087] 2. Feeding device; 21. Mixing head; 22. Feeding channel;

[0088] 3. First flow channel; 31. Inflow end; 32. Outflow end; 33. Bend; 34. Overflow well;

[0089] 4. Exhaust assembly; 41. Exhaust valve; 42. Exhaust valve drive;

[0090] 5. Second flow channel;

[0091] 6. Transition channel;

[0092] 100, human-computer interaction unit; 200, control unit; 300, first pressure sensor; 400, second pressure sensor. DETAILED DESCRIPTION

[0093] Embodiments of the present application will be described in detail below, examples of which are shown in the accompanying drawings, and the components of the embodiments of the present application generally described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the application claimed for protection, but merely represents selected embodiments of the present application.

[0094] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0095] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0096] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0097] The following will be combined Figure 1 and Fig. 20 The technical solution of the present application is described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0098] Figure 1 It is a structural schematic diagram of a coating chamber exhaust structure for an in-mold coating process provided by an exemplary embodiment of the present application; Figure 2 It is a structural schematic diagram of a painting cavity exhaust structure for an in-mold painting process provided by another exemplary embodiment of the present application.

[0099] The first aspect of the present application provides a coating cavity exhaust structure for an in-mold coating process, referring to Figure 1 and Figure 2 As shown, it includes a feeding device 2 connected to the coating chamber 1, a first flow channel 3 and an exhaust component 4.

[0100] The inlet end 31 of the first flow channel 3 is communicated with the coating chamber 1 for receiving fluid.

[0101] In some specific examples, the fluid received by the first flow channel 3 may be overflowed painting paint, or may be gas inside the painting chamber 1 .

[0102] When the feeding device 2 starts to feed the coating paint into the coating chamber 1 , the air inside the coating chamber 1 is forced to flow into the first flow channel 3 ; when the coating paint is transferred, the coating paint will also flow into the first flow channel 3 .

[0103] For some specific examples, see Figure 2 As shown, the connecting position between the feeding device 2 and the coating chamber 1 corresponds to the connecting position between the first flow channel 3 and the coating chamber 1, that is, they can be located on the front and back sides, left and right sides, upper and lower sides, or other corresponding sides of the coating chamber 1, so that the paint can flow through the substrate in the coating chamber before reaching the inlet end 31 of the first flow channel 3.

[0104] In some specific examples, the cross-sectional shape of the first flow channel 3 may be circular or other irregular shapes.

[0105] In some specific examples, the fluid received by the first flow channel 3 may be overflowed painting paint, or may be gas inside the painting chamber 1 .

[0106] The exhaust component 4 is disposed at the outflow end of the first flow channel 3 for exhausting gas.

[0107] In some specific examples, the exhaust gas may be the air in the coating chamber 1 or other gas generated by the coating.

[0108] At least one curved portion 33 is formed on the first flow channel 3 to increase the resistance to fluid flow. The curved portion not only promotes the discharge of gas and reduces defects such as bubbles and trapped air on the product surface caused by gas accumulation, but also increases the resistance to fluid flow, so that the paint can be filled more evenly in the coating cavity, avoiding the problem of local insufficient filling or overfilling, and improving the appearance quality and functionality of the product.

[0109] In some specific examples, the feeding device 2 is connected to the mixing head 21, the mixing head 21 is connected to the feeding channel 22, and the feeding channel 22 is connected to the coating chamber 1, so that the coating paint can be mixed from the feeding device 2 into the mixing head 21 and then fed into the coating chamber 1 through the feeding channel 22.

[0110] Figure 3 It is a structural schematic diagram of a painting cavity exhaust structure for an in-mold painting process provided by yet another exemplary embodiment of the present application.

[0111] In some embodiments of the first aspect, refer to Figure 1 and Figure 3 The coating cavity exhaust structure used in the in-mold coating process also includes a second flow channel 5 and a transition flow channel 6.

[0112] The second flow channel 5 is directly connected to the coating chamber 1, so that the fluid can enter the second flow channel 5 from the coating chamber 1. The flow cross-sectional area of ​​the second flow channel 5 is significantly smaller than the flow cross-sectional area of ​​the coating chamber 1. This design increases the flow resistance of the fluid, thereby effectively controlling the flow speed of the fluid and ensuring uniform filling of the fluid in the coating chamber. It is particularly suitable for coatings with excellent fluidity (such as PUR / PUA polyurethane or polyurea coatings), avoiding the problem of local overfilling or underfilling caused by rapid flow.

[0113] The second flow channel 5, the transition flow channel 6 and the first flow channel 3 are connected in sequence to form a continuous flow channel system. In particular, the transition flow channel 6 is an arc-shaped flow channel, and the inclination angle of the transition flow channel changes from large to small along the flow direction of the coating material.

[0114] The inclination angle of the transition channel refers to the inclination angle of the transition channel relative to the horizontal plane. This angle decreases along the flow direction of the coating material. In other words, the angle formed by the tangent of the arc-shaped transition channel and the vertical direction gradually increases. This design not only guides the smooth turning of the fluid, reduces turbulence and pressure loss, but also promotes the effective separation and discharge of gas. For example, when the paint flows from the coating chamber 1 to the first flow channel 3, the arc-shaped design of the transition channel 6 enables the fluid to change the flow direction smoothly, avoiding unstable flow caused by sudden changes in direction, thereby improving the stability and consistency of the coating process.

[0115] In some specific examples, the coating chamber 1, the second flow channel 5, the transition flow channel 6, and the first flow channel 3 are sequentially connected, and they may be fixedly connected to each other by welding or other means, or may be fixed by a detachable means such as screws.

[0116] In some embodiments of the first aspect, the height of the second flow channel 5 is 0.05 mm to 5 mm, and the width is 0.1 mm to 8 mm. In some specific examples, the height of the second flow channel 5 can be 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 3 mm, 4 mm, 5 mm, etc. The width of the second flow channel 5 can be 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, etc.

[0117] In this embodiment, by limiting the height and width of the second flow channel 5, the flow resistance of the fluid can be precisely controlled. At the same time, the narrow design of the second flow channel 5 increases the turbulence of the fluid, which helps the gas to separate from the coating and be taken out, thereby improving the gas discharge efficiency and reducing the occurrence of bubbles or trapped air. When the height of the second flow channel 5 is less than 0.05mm or the width is greater than 8mm, the fluid flow resistance will be too large, making it difficult for the coating to pass through the second flow channel 5, which may cause local overfilling, and increase the risk of the flow channel being blocked by impurities or solidified coating, causing the system to fail to work properly; when the height of the second flow channel 5 is greater than 5mm or the width is less than 0.1mm, the fluid flow resistance will be reduced, allowing the coating to flow quickly into the coating cavity, which may cause local insufficient filling or uneven filling, affecting product quality, and reducing the turbulence of the fluid, which is not conducive to the separation of gas from the coating and being taken out, reducing the gas discharge efficiency, and increasing the risk of bubbles or trapped air.

[0118] In some embodiments of the first aspect, along the flow direction of the coating material, the inclination angle of the transition channel 6 ranges from 50° to 1°.

[0119] In some specific examples, the angle can gradually decrease from an angle value such as 30°, 35°, 40°, 45°, 48°, 49° or 50° to an angle value such as 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°.

[0120] The angle variation range of the inclination angle can adapt to different coating materials and different coating injection speeds, so that the coating material can smoothly transition from the second flow channel with a height of 0.05-5mm and a width of 0.5-8mm to the first flow channel, reducing turbulence and pressure loss during turning, ensuring a smooth and smooth flow process, and also making it easier for gas to be brought out and discharged, further reducing the occurrence of bubbles or trapped air.

[0121] Figure 4 It is a structural schematic diagram of a painting cavity exhaust structure for an in-mold painting process provided by yet another exemplary embodiment of the present application.

[0122] In some embodiments of the first aspect, refer to Figure 4 The curved portion 33 is at least one of a U-shaped curved portion, an L-shaped curved portion and an S-shaped curved portion.

[0123] In this embodiment, the U-shaped bend, L-shaped bend and S-shaped bend can be selected or used in combination according to actual needs to more accurately adjust the flow resistance of the fluid and ensure uniform filling of the paint in the coating chamber, which is particularly suitable for paints with different viscosities and fluidities.

[0124] In some specific examples, the bend 33 may include a U-shaped bend, an L-shaped bend and an S-shaped bend, and the number of the bends may be 1, 2, 3 or more, or may include a U-shaped bend and an L-shaped bend, or an L-shaped bend and an S-shaped bend, or a U-shaped bend and an S-shaped bend, or a U-shaped bend, an L-shaped bend and an S-shaped bend, or a U-shaped bend, an L-shaped bend and an S-shaped bend.

[0125] In some embodiments of the first aspect, an overflow well 34 is provided between the curved portion 33 of the first flow channel 3 and the exhaust component 4, which can receive excess paint overflowing from the first flow channel 3 to prevent the paint from flowing directly out of the exhaust component 4 and contaminating the mold or affecting the coating quality. At the same time, the exhaust component 4 can be protected from paint clogging, ensuring its normal operation and extending the service life of the exhaust component 4.

[0126] In some specific examples, the overflow well 34 may be a cylindrical or other irregularly shaped container to store overflowing painting paint.

[0127] In some embodiments of the first aspect, the exhaust assembly 4 includes an exhaust valve 41 and an exhaust valve driver 42. The exhaust valve driver 42 is connected to the exhaust valve 41 and is used to control the opening and closing of the exhaust valve 41, thereby realizing automatic control of the exhaust valve 41, reducing the need for manual intervention and improving production efficiency.

[0128] In some specific examples, the exhaust valve 41 may be a core-pulling valve.

[0129] Figure 5 It is a schematic structural diagram of a painting chamber exhaust system for an in-mold painting process provided by an exemplary embodiment of the present application.

[0130] The second aspect of the present application provides a coating chamber exhaust system for an in-mold coating process, see Figure 5 , including the coating chamber exhaust structure described in the first embodiment, and also including a human-computer interaction unit 100, a control unit 200, a first pressure sensor 300, and a second pressure sensor 400;

[0131] The human-machine interaction unit 100 is electrically connected to the control unit 200, providing a user with a friendly operation interface, allowing the user to conveniently input various instruction data information, such as preset pressure value, feeding speed, etc. For example, the user can set specific coating parameters through the touch screen or keyboard to ensure that the system is accurately controlled according to the needs.

[0132] The control unit 200 is electrically connected to the feeding device 2 and the exhaust component 4, and is responsible for coordinating the work of each component. The control unit 200 controls the start and stop of the feeding device 2 according to the instruction data information input by the user to ensure that the paint enters the coating chamber 1 at an appropriate time. For example, when using polyurethane paint with moderate viscosity, the control unit can start the feeding device according to the set speed to ensure that the paint is evenly distributed.

[0133] The control unit 200 is also responsible for controlling the on / off action of the exhaust assembly 4 to ensure that the gas is exhausted at an appropriate time. For example, when it is detected that the pressure in the coating chamber 1 reaches a preset value, the control unit 200 will immediately close the exhaust assembly 4 to prevent excessive exhaust from affecting the coating quality.

[0134] In some specific examples, the control unit 200 is electrically connected to the exhaust valve driver 42 of the exhaust assembly 4 to control the opening and closing of the exhaust valve 41 .

[0135] The first pressure sensor 300 is disposed on the wall of the coating chamber 1 at the connection with the feeding device 2 and is electrically connected to the control unit 200 for real-time detection of the pressure value in the coating chamber 1 and transmission of the data to the control unit 200. This real-time monitoring mechanism realizes closed-loop control and ensures the stability and consistency of the coating process.

[0136] The first pressure sensor 400 is disposed at the inflow end 31 of the first flow channel 3 and is electrically connected to the control unit 200 for detecting the pressure value at the inflow end 31 of the first flow channel 3 in real time and transmitting the data to the control unit 200 .

[0137] The second aspect of the present application provides a coating chamber exhaust system for in-mold coating process, which can not only conveniently input command data information through the human-computer interaction unit 100 to realize automatic control of the system, but also accurately control the switching timing of the exhaust component 4, thereby reducing the occurrence of bubbles and trapped air, and improving the appearance quality and functionality of the product. It can also flexibly adjust the feeding speed of the feeding device 2 and the switching time and frequency of the exhaust component 4 according to different coating process requirements, and is suitable for various types of coating chambers 1 and coating materials, thereby enhancing the adaptability and flexibility of the system.

[0138] Figure 6 It is a flow chart of a method for exhausting a painting chamber for an in-mold painting process provided by an exemplary embodiment of the present application.

[0139] The third aspect of the present application provides a coating chamber exhaust method for an in-mold coating process, such as Figure 6 As shown, the method is performed by the above-mentioned coating chamber exhaust system for in-mold coating process, and includes:

[0140] S100, presetting a pressure value in a control unit through a human-machine interaction unit.

[0141] In some embodiments, the preset pressure value is any value between 20 bar and 120 bar, such as 20 bar, 25 bar, 30 bar, 40 bar, 50 bar, 60 bar, 70 bar, 80 bar, 90 bar, 100 bar, 110 bar, 115 bar, 120 bar, etc. Different preset pressure values ​​can be appropriately optimized and adjusted according to different coating viscosities, fluidities, product weights, and coating wall thicknesses to ensure the best coating effect. By setting a reasonable preset pressure value, the pressure in the coating cavity can be established and monitored in real time, so that the product in the coating cavity can be fully filled, and the appearance quality and functionality of the product can be improved. For example: a lower preset pressure value is suitable for coatings with poor fluidity, low viscosity, low temperature, slow flow rate, or small product weight, reducing flow resistance and ensuring smooth filling of the coating. A higher preset pressure value is suitable for special processes that require fast filling or coatings with good fluidity, high viscosity, high temperature, fast flow rate, and heavy product weight, ensuring that the coating is evenly distributed in a short time.

[0142] In some specific examples, the user can also input the speed at which the feeding device conveys the paint to the control unit through the human-computer interaction unit.

[0143] S200, the coating chamber is connected to the outside, and the feeding device conveys coating paint into the coating chamber.

[0144] In some specific examples, step S200 includes:

[0145] S201, the control unit sends a command to the exhaust component to open it, ensuring that the coating chamber is connected to the outside world and allowing the gas to be discharged smoothly.

[0146] S202: After the exhaust assembly is turned on, the control unit starts the feeding device to start conveying paint to the coating chamber.

[0147] In some embodiments, the user can set the feeding speed to 5 g / min to 700 g / min through the human-computer interaction unit.

[0148] In this embodiment, the conveying speed of 5g / min to 700g / min covers a wide range from extremely low speed to high speed, which is suitable for different types of coating processes and coating characteristics. According to the different parameters such as the coating layer thickness and weight of the product, the feeding flow rate can be 5g / min, or 700g / min, or values ​​in between such as 50g / min, 100g / min, 200g / min, 300g / min, 400g / min, 500g / min, 600g / min, 700g / min, etc. The specific choice depends on the actual coating weight of the product. By setting a reasonable conveying speed, the uniform distribution of the coating in the coating cavity can be ensured, avoiding the problem of insufficient local filling or overfilling, and improving the appearance quality and functionality of the product.

[0149] In some embodiments, the preset pressure value of the mold exhaust system used for the in-mold coating process is 20 bar to 120 bar, which is suitable for products of the in-mold coating process of 5g-5000g. That is, whether it is a 5g coated product or a 5000g coated product, it is ensured that the pressure in the coating mold cavity is 20 bar-120 bar to complete the coating process, so that a relatively perfect coated product can be obtained.

[0150] In some embodiments, the coating temperature is 30° C. to 90° C., and the viscosity is 100 cps to 300 cps. For example, the coating temperature can be 30° C., 31° C., 32° C., 35° C., 40° C., 50° C., 60° C., 70° C., 80° C., 85° C., 88° C., 89° C., 90° C., etc. The viscosity can be 100 cps, 105 cps, 110 cps, 120 cps, 150 cps, 200 cps, 250 cps, 280 cps, 290 cps, 295 cps, 300 cps, etc.

[0151] This embodiment is applicable to coating materials of different temperatures and viscosities, that is, it can meet the requirements of different production processes, has wide applicability and flexibility, and improves production efficiency and economic benefits.

[0152] In some embodiments, when the feeding device delivers the coating paint into the coating chamber, the temperature inside the coating chamber is 80° C. to 130° C. For example, the temperature inside the coating chamber may be 80° C., 81° C., 82° C., 85° C., 90° C., 100° C., 110° C., 120° C., 125° C., 128° C., 129° C., 130° C., etc.

[0153] In this embodiment, a higher temperature can accelerate the curing reaction of the coating, shorten the curing time, and improve production efficiency. For some thermosetting coatings, such as polyurethane or polyurea coatings, appropriately increasing the temperature can promote the cross-linking reaction and obtain better coating performance.

[0154] S300 , the first pressure sensor and the second pressure sensor detect pressure values ​​and transmit them to the control unit.

[0155] When the paint enters the coating chamber, the air inside it is squeezed, which causes the pressure value to change. The first pressure sensor transmits the detected pressure changes to the control unit;

[0156] At the same time, the second pressure sensor monitors the pressure value of the inflow end of the first flow channel in real time and transmits it to the control unit.

[0157] S400: When the control unit determines that the pressure value detected by the second pressure sensor is greater than 0 bar, the exhaust component is controlled to close gas exhaust.

[0158] The second pressure sensor detects the pressure value at the inflow end of the first flow channel. The second pressure sensor closes the exhaust component when it detects that the pressure value is greater than 0. After the gas is discharged, the pressure is maintained and filled continuously, which reduces the occurrence of bubbles and trapped air and improves the appearance quality and functionality of the product. The whole process is automatically completed by the control system, which reduces the need for manual intervention and improves production efficiency. The control unit can flexibly adjust the feeding speed of the feeding device and the switching time and frequency of the exhaust component according to different coating process requirements. It is suitable for various types of coating chambers and coatings, which enhances the adaptability and flexibility of the system.

[0159] S500, continue to maintain pressure and fill until the coating process is completed. During the coating process, the pressure value detected by the first pressure sensor can reach a preset pressure value.

[0160] During the process of the feeding device conveying the coating paint into the coating chamber until the entire coating process is completed, the pressure value detected by the first pressure sensor received by the control unit can reach the preset pressure value, thereby ensuring that the required pressure value has been established for this coating process, thereby ensuring the good effects of the prepared coating product such as density and bubble-free.

[0161] The following is a specific embodiment of a coating chamber exhaust method for an in-mold coating process provided by the present application:

[0162] The equipment and materials used in the following examples of this application:

[0163] Substrate material: transparent PC2067;

[0164] Coating material: Liming PUR 8001;

[0165] The coating cavity used for the test: the coating cavity for the crystal gear lever in-mold coating;

[0166] The first flow channel used in the test has an L-shaped bend;

[0167] The angle formed by the tangent line of the transition flow channel used in the test and the vertical direction varies in the range of 1° to 50°;

[0168] Equipment used for the test: KraussMaffei injection molding machine and in-mold coating equipment, mold temperature control system;

[0169] The following examples of this application test some process conditions:

[0170] Substrate material temperature: transparent PC2067 260℃-310℃

[0171] Coating material: Liming PUR 8001A.B 50℃-80℃

[0172] Coating material vacuum degree: ≤-0.3Bar—≤-0.4Bar

[0173] Coating pouring pressure: ISO feed pressure: 165Bar, Poly feed pressure: 170bar

[0174] Example 1

[0175] Initial state: the injection molding machine completes the mold closing operation, the substrate is fixed inside the mold, a coating cavity 1 is formed between the mold and the substrate, and the width of the second flow channel 5 is 2 mm and the height is 1 mm. The control unit 200 initializes the system, and the user sets the pressure preset value of 50 bar in the control unit 200 through the human-machine interaction unit 100 to ensure that all components are in standby state;

[0176] The control unit 200 controls the exhaust valve driving member 42 to operate, so that the exhaust valve 41 is opened, so that the coating chamber 1 is connected with the outside, and the air in the coating chamber 1 can be discharged; when the exhaust valve 41 is opened, the initial pressure in the coating chamber 1 is about 0 bar;

[0177] The control unit 200 controls the feeding device 2 to start, and delivers the polyurethane coating with a temperature of 70°C and a viscosity of 170 cPs to the coating chamber 1 with a temperature of 110°C through the mixing head 21 and the feeding channel 22 at a speed of 34 g / min. At the same time, isocyanate (ISO) and polyol (Poly) are delivered to the mixing head, and the ISO feed flow rate is 23 g / s; the Poly feed flow rate is 11 g / s.

[0178] The first pressure sensor 300 monitors the pressure change in the coating chamber 1 in real time, and the second pressure sensor 400 monitors the pressure change at the inflow end 31 of the first flow channel 3 in real time, and transmits the detected pressure data to the control unit 200;

[0179] When the second pressure sensor detects a pressure value greater than 0, the control unit 200 controls the exhaust valve driving member 42 to operate so that the exhaust valve 41 is closed;

[0180] The control unit 200 controls the feeding device 2 to continue conveying the paint and perform pressure-maintaining filling until the filling of the coating paint is completed;

[0181] In the above process, the pressure value detected by the first pressure sensor 300 and received by the control unit 200 can reach the pressure value of 50 bar preset by the user.

[0182] After filling, it is cooled and solidified, the coating cavity is opened, and the coated product is taken out.

[0183] Example 2

[0184] Initial state: the injection molding machine completes the mold closing operation, the substrate is fixed inside the mold, a coating cavity 1 is formed between the mold and the substrate, and the width of the second flow channel 5 is 8 mm and the height is 2.5 mm. The control unit 200 initializes the system, and the user sets the pressure preset value of 120 bar in the control unit 200 through the human-machine interaction unit 100 to ensure that all components are in standby state;

[0185] The control unit 200 controls the exhaust valve driving member 42 to operate, so that the exhaust valve 41 is opened, so that the coating chamber 1 is connected with the outside, and the air in the coating chamber 1 can be discharged; when the exhaust valve 41 is opened, the initial pressure in the coating chamber 1 is about 0 bar;

[0186] The control unit 200 controls the feeding device 2 to start, and delivers the polyurethane coating with a temperature of 70°C and a viscosity of 170 cPs to the coating chamber 1 with a temperature of 110°C through the mixing head 21 and the feeding channel 22 at a speed of 34 g / min. At the same time, isocyanate (ISO) and polyol (Poly) are delivered to the mixing head, and the ISO feed flow rate is 23 g / s; the Poly feed flow rate is 11 g / s.

[0187] The first pressure sensor 300 monitors the pressure change in the coating chamber 1 in real time, and the second pressure sensor 400 monitors the pressure change at the inflow end 31 of the first flow channel 3 in real time, and transmits the detected pressure data to the control unit 200;

[0188] When the second pressure sensor detects a pressure value greater than 0, the control unit 200 controls the exhaust valve driving member 42 to operate so that the exhaust valve 41 is closed;

[0189] The control unit 200 controls the feeding device 2 to continue conveying the paint and perform pressure-maintaining filling until the filling is completed;

[0190] In the above process, the pressure value detected by the first pressure sensor 300 and received by the control unit 200 can reach the pressure value of 120 bar preset by the user.

[0191] After filling, it is cooled and solidified, the coating cavity is opened, and the coated product is taken out.

[0192] Example 3

[0193] Initial state: the injection molding machine completes the mold closing operation, the substrate is fixed inside the mold, a coating cavity 1 is formed between the mold and the substrate, and the width of the second flow channel 5 is 4 mm and the height is 4.5 mm. The control unit 200 initializes the system, and the user sets the pressure preset value of 20 bar in the control unit 200 through the human-machine interaction unit 100 to ensure that all components are in standby state;

[0194] The control unit 200 controls the exhaust valve driving member 42 to operate, so that the exhaust valve 41 is opened, so that the coating chamber 1 is connected with the outside, and the air in the coating chamber 1 can be discharged; when the exhaust valve 41 is opened, the initial pressure in the coating chamber 1 is about 0 bar;

[0195] The control unit 200 controls the feeding device 2 to start, and delivers the polyurethane coating with a temperature of 70°C and a viscosity of 170 cPs to the coating chamber 1 with a temperature of 110°C through the mixing head 21 and the feeding channel 22 at a speed of 34 g / min. At the same time, isocyanate (ISO) and polyol (Poly) are delivered to the mixing head, and the ISO feed flow rate is 23 g / s; the Poly feed flow rate is 11 g / s.

[0196] The first pressure sensor 300 monitors the pressure change in the coating chamber 1 in real time, and the second pressure sensor 400 monitors the pressure change at the inflow end 31 of the first flow channel 3 in real time, and transmits the detected pressure data to the control unit 200;

[0197] When the second pressure sensor detects a pressure value greater than 0, the control unit 200 controls the exhaust valve driving member 42 to operate so that the exhaust valve 41 is closed;

[0198] The control unit 200 controls the feeding device 2 to continue conveying the paint and perform pressure-maintaining filling until the filling is completed;

[0199] In the above process, the pressure value detected by the first pressure sensor 300 received by the control unit 200 can reach the pressure value 20 bar preset by the user;

[0200] After filling, it is cooled and solidified, the coating cavity is opened, and the coated product is taken out.

[0201] Example 4

[0202] Initial state: the injection molding machine completes the mold closing operation, the substrate is fixed inside the mold, a coating cavity 1 is formed between the mold and the substrate, and the width of the second flow channel 5 is 0.1 mm and the height is 0.05 mm. The control unit 200 initializes the system, and the user sets the pressure preset value of 120 bar in the control unit 200 through the human-machine interaction unit 100 to ensure that all components are in standby state;

[0203] The control unit 200 controls the exhaust valve driving member 42 to operate, so that the exhaust valve 41 is opened, so that the coating chamber 1 is connected with the outside, and the air in the coating chamber 1 can be discharged; when the exhaust valve 41 is opened, the initial pressure in the coating chamber 1 is about 0 bar;

[0204] The control unit 200 controls the feeding device 2 to start, and delivers the polyurethane coating with a temperature of 70°C and a viscosity of 170 cPs to the coating chamber 1 with a temperature of 110°C through the mixing head 21 and the feeding channel 22 at a speed of 34 g / min. At the same time, isocyanate (ISO) and polyol (Poly) are delivered to the mixing head, and the ISO feed flow rate is 23 g / s; the Poly feed flow rate is 11 g / s.

[0205] The first pressure sensor 300 monitors the pressure change in the coating chamber 1 in real time, and the second pressure sensor 400 monitors the pressure change at the inflow end 31 of the first flow channel 3 in real time, and transmits the detected pressure data to the control unit 200;

[0206] When the second pressure sensor detects a pressure value greater than 0, the control unit 200 controls the exhaust valve driving member 42 to operate so that the exhaust valve 41 is closed;

[0207] The control unit 200 controls the feeding device 2 to continue conveying the paint and perform pressure-maintaining filling until the filling is completed;

[0208] In the above process, the pressure value detected by the first pressure sensor 300 received by the control unit 200 can reach the pressure value 120 bar preset by the user;

[0209] After filling, it is cooled and solidified, the coating cavity is opened, and the coated product is taken out.

[0210] Comparative Example 1

[0211] Initial state: the injection molding machine completes the mold closing operation, the substrate is fixed inside the mold, a coating cavity 1 is formed between the mold and the substrate, and the width of the second flow channel 5 is 0.1 mm and the height is 6 mm. The control unit 200 initializes the system, and the user sets the pressure preset value of 20 bar in the control unit 200 through the human-machine interaction unit 100 to ensure that all components are in standby state;

[0212] The control unit 200 controls the exhaust valve driving member 42 to operate, so that the exhaust valve 41 is opened, so that the coating chamber 1 is connected with the outside, and the air in the coating chamber 1 can be discharged; when the exhaust valve 41 is opened, the initial pressure in the coating chamber 1 is about 0 bar;

[0213] The control unit 200 controls the feeding device 2 to start, and delivers the polyurethane coating with a temperature of 70°C and a viscosity of 170 cPs to the coating chamber 1 with a temperature of 110°C through the mixing head 21 and the feeding channel 22 at a speed of 34 g / min. At the same time, isocyanate (ISO) and polyol (Poly) are delivered to the mixing head, and the ISO feed flow rate is 23 g / s; the Poly feed flow rate is 11 g / s.

[0214] The first pressure sensor 300 monitors the pressure change in the coating chamber 1 in real time and transmits the detected pressure data to the control unit 200;

[0215] At this time, since the width of the second flow channel 5 is 0.1mm and the height is 5.1mm, the paint directly enters the overflow well from the overflow flow channel area after filling the product, without causing pressure changes, which leads to incomplete filling of the paint layer and insufficient pressure maintenance in the mold, resulting in the inability to effectively discharge bubbles. The appearance of the product paint layer is poor.

[0216] Comparative Example 2

[0217] Initial state: the injection molding machine completes the mold closing operation, the substrate is fixed inside the mold, a coating cavity 1 is formed between the mold and the substrate, and the width of the second flow channel 5 is 8.5 mm and the height is 0.03 mm. The control unit 200 initializes the system, and the user sets the pressure preset value of 130 bar in the control unit 200 through the human-machine interaction unit 100 to ensure that all components are in standby state;

[0218] The control unit 200 controls the exhaust valve driving member 42 to operate, so that the exhaust valve 41 is opened, so that the coating chamber 1 is connected with the outside, and the air in the coating chamber 1 can be discharged; when the exhaust valve 41 is opened, the initial pressure in the coating chamber 1 is about 0 bar;

[0219] The control unit 200 controls the feeding device 2 to start, and delivers the polyurethane coating with a temperature of 70°C and a viscosity of 170 cPs to the coating chamber 1 with a temperature of 110°C through the mixing head 21 and the feeding channel 22 at a speed of 34 g / min. At the same time, isocyanate (ISO) and polyol (Poly) are delivered to the mixing head, and the ISO feed flow rate is 23 g / s; the Poly feed flow rate is 11 g / s.

[0220] The first pressure sensor 300 monitors the pressure change in the coating chamber 1 in real time, and the second pressure sensor 400 monitors the pressure change at the inflow end 31 of the first flow channel 3 in real time, and transmits the detected pressure data to the control unit 200;

[0221] When the second pressure sensor detects a pressure value greater than 0, the control unit 200 controls the exhaust valve driving member 42 to operate so that the exhaust valve 41 is closed;

[0222] The control unit 200 controls the feeding device 2 to continue conveying the paint and perform pressure-maintaining filling until the filling is completed;

[0223] In the above process, the pressure value detected by the first pressure sensor 300 received by the control unit 200 can reach the pressure value 130 bar preset by the user;

[0224] After filling, it is cooled and solidified, the coating cavity is opened, and the coated product is taken out.

[0225] Comparative Example 3

[0226] Initial state: the injection molding machine completes the mold closing operation, the substrate is fixed inside the mold, a coating cavity 1 is formed between the mold and the substrate, and the width of the second flow channel 5 is 1 mm and the height is 6 mm. The control unit 200 initializes the system, and the user sets the pressure preset value of 10 bar in the control unit 200 through the human-machine interaction unit 100 to ensure that all components are in standby state;

[0227] The control unit 200 controls the exhaust valve driving member 42 to operate, so that the exhaust valve 41 is opened, so that the coating chamber 1 is connected with the outside, and the air in the coating chamber 1 can be discharged; when the exhaust valve 41 is opened, the initial pressure in the coating chamber 1 is about 0 bar;

[0228] The control unit 200 controls the feeding device 2 to start, and delivers the polyurethane coating with a temperature of 70°C and a viscosity of 170 cPs to the coating chamber 1 with a temperature of 110°C through the mixing head 21 and the feeding channel 22 at a speed of 34 g / min. At the same time, isocyanate (ISO) and polyol (Poly) are delivered to the mixing head, and the ISO feed flow rate is 23 g / s; the Poly feed flow rate is 11 g / s.

[0229] The first pressure sensor 300 monitors the pressure change in the coating chamber 1 in real time, and the second pressure sensor 400 monitors the pressure change at the inflow end 31 of the first flow channel 3 in real time, and transmits the detected pressure data to the control unit 200;

[0230] When the second pressure sensor detects a pressure value greater than 0, the control unit 200 controls the exhaust valve driving member 42 to operate so that the exhaust valve 41 is closed;

[0231] The control unit 200 controls the feeding device 2 to continue conveying the paint and perform pressure-maintaining filling until the filling is completed;

[0232] In the above process, the pressure value detected by the first pressure sensor 300 received by the control unit 200 can reach the pressure value 10 bar preset by the user;

[0233] After filling, it is cooled and solidified, the coating cavity is opened, and the coated product is taken out.

[0234] It can be seen from the above Examples 1 to 4 and Comparative Examples 1 to 3 that:

[0235] The pressure change during the coating process of Example 1 is shown in FIG. Figure 7 As shown, the final product is Figure 8 As shown, it can be seen that in Example 1, when the width of the second flow channel 5 is 2 mm, the height is 1 mm, and the preset pressure value is 50 bar, good pressure-maintaining filling can be performed, the bubbles in the coating layer of the obtained product are effectively discharged, and the product appearance is good.

[0236] The pressure change during the coating process of Example 2 is shown in FIG. Fig. 9 As shown, the final product is Fig.10 As shown, it can be seen that in Example 2, when the width of the second flow channel 5 is 8 mm, the height is 2.5 mm, and the preset pressure value is 120 bar, better pressure-maintaining filling can be performed, the bubbles in the coating layer of the obtained product are effectively discharged, and the product appearance is good.

[0237] The pressure change during the coating process of Example 3 is shown in FIG. Fig.11 As shown, the final product is Fig.12 As shown, it can be seen that in Example 3, under the conditions that the width of the second flow channel 5 is 4 mm, the height is 5 mm, and the preset pressure value is 20 bar, better pressure-maintaining filling can be performed, the bubbles in the coating layer of the obtained product are effectively discharged, and the product appearance is good.

[0238] Example 4 Pressure change during coating process Fig.13 As shown, the final product is Fig.14 As shown, it can be seen that in Example 4, under the conditions that the width of the second flow channel 5 is 0.1 mm, the height is 0.05 mm, and the preset pressure value is 120 bar, the coating is well pressure-maintained and filled, the coating is dense, there are no bubbles, trapped air and other adverse effects on the surface, and the product appearance is good.

[0239] The pressure change diagram during the coating process of comparative example 1 is as follows Fig.15 As shown, the final product is Fig.16As shown, it can be seen that in comparative example 1, under the conditions that the width of the second flow channel 5 is 0.1 mm, the height is 5.1 mm, and the preset pressure value is 130 bar, the overflow resistance is insufficient, so that the coating flows directly into the overflow well after filling, the cavity pressure has not changed, the coating layer is not completely filled, and the pressure maintenance in the mold is insufficient, resulting in the inability to effectively discharge the bubbles, which ultimately makes the appearance of the product coating layer poor.

[0240] The pressure change diagram during the coating process of comparative example 2 is as follows Fig.17 As shown, the final product is Fig.18 As shown, it can be seen that in Comparative Example 2, under the conditions that the width of the second flow channel 5 is 8.5 mm, the height is 0.03 mm, and the preset pressure value is 130 bar, the bubbles in the product coating layer can be discharged, but overflow and flash appear in the overflow well, and the product and overflow areas have poor mold support.

[0241] The pressure change diagram of the coating process of comparative example 3 is as follows Fig.19 As shown, the final product is Fig. 20 As shown, it can be seen that in comparative example 3, under the conditions that the width of the second flow channel 5 is 1 mm, the height is 6 mm, and the preset pressure value is 10 bar, the coating filling degree is insufficient, resulting in bubbles, trapped air and other adverse effects on the product surface.

[0242] According to the above embodiments and comparative examples, when a certain overflow resistance is provided in the coating chamber, even if the width of the second flow channel 5 is 0.1-8 mm and the height is 0.05-5 mm, when the second pressure sensor 400 detects a pressure value greater than 0 bar, that is, when the coating paint flows into the first flow channel 3, the exhaust valve is closed for pressure-maintaining filling, and the pressure value detected by the first pressure sensor 300 during the entire coating process can reach the preset pressure value, which can make the coating layer denser and reduce adverse effects such as bubbles and trapped air.

[0243] It should be noted that the technical solutions in the various embodiments of the present application can be combined with each other, but the basis for the mutual combination is that it can be implemented by ordinary technicians in the field; when the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist, that is, it does not belong to the scope of protection of this application.

[0244] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A coating chamber exhaust structure for in-mold coating process, characterized in that: It includes a second flow channel, a transition flow channel, a first flow channel and an exhaust component, wherein the coating chamber, the second flow channel, the transition flow channel and the first flow channel are connected in sequence. Wherein, the flow cross-sectional area of ​​the second flow channel is smaller than the flow cross-sectional area of ​​the coating chamber; The transition channel is an arc-shaped channel, and the inclination angle of the transition channel gradually decreases along the flow direction of the fluid; The first flow channel includes an inflow end and an outflow end, the inflow end of the first flow channel is connected to the transition flow channel, and the outflow end of the first flow channel is connected to the exhaust component; The first flow channel is formed with at least one curved portion for increasing fluid flow resistance.

2. The coating chamber exhaust structure for in-mold coating process according to claim 1, characterized in that: The second flow channel has a height of 0.05 mm to 5 mm and a width of 0.1 mm to 8 mm.

3. The coating chamber exhaust structure for in-mold coating process according to claim 1, characterized in that: Along the fluid flow direction, the transition channel inclination angle varies in the range of 50° to 1°.

4. The coating chamber exhaust structure for in-mold coating process according to claim 1, characterized in that: The curved portion is at least one of a U-shaped curved portion, an L-shaped curved portion and an S-shaped curved portion.

5. The coating chamber exhaust structure for in-mold coating process according to claim 1, characterized in that: An overflow well is provided between the curved portion of the first flow channel and the exhaust component, and when the fluid includes paint, the overflow well can receive the paint, thereby preventing the paint in the fluid from entering the exhaust component.

6. The coating chamber exhaust structure for in-mold coating process according to claim 1, characterized in that: The exhaust assembly comprises an exhaust valve and an exhaust valve driver, wherein the exhaust valve driver is connected to the exhaust valve and is used to control the opening and closing of the exhaust valve.

7. A coating chamber exhaust system for an in-mold coating process, characterized in that: The coating chamber exhaust structure comprises the coating chamber exhaust structure according to any one of claims 1 to 6, and further comprises a human-machine interaction unit, a control unit, a first pressure sensor and a second pressure sensor; The human-computer interaction unit is electrically connected to the control unit and is used for the user to input instruction data information; The control unit is electrically connected to the feeding device and is used to control the start and stop of the feeding action of the feeding device; The control unit is electrically connected to the exhaust assembly and is used to control the switch of the exhaust assembly; The first pressure sensor is arranged on the wall of the coating chamber at the connection with the feeding device, and the first pressure sensor is electrically connected to the control unit, and is used to detect the pressure value in the coating chamber and transmit it to the control unit; The second pressure sensor is disposed at the inflow end of the first flow channel. The second pressure sensor is electrically connected to the control unit and is used to detect the pressure value at the inflow end of the first flow channel and transmit it to the control unit.

8. A method for exhausting a coating chamber for an in-mold coating process, characterized in that: The method is performed by the painting chamber exhaust system for the in-mold painting process according to claim 7, and the method comprises: Presetting the pressure value in the control unit through the human-machine interaction unit; The exhaust assembly is opened to connect the coating chamber with the outside world; The feeding device conveys the coating material into the coating chamber; The first pressure sensor and the second pressure sensor detect pressure values ​​and transmit them to the control unit; When the pressure value detected by the second pressure sensor is greater than 0 bar, the control unit controls the exhaust component to close the gas exhaust; During the process of the feeding device conveying the coating paint into the coating chamber, the pressure value detected by the first pressure sensor and received by the control unit can reach a preset value.

9. The method for exhausting the coating chamber for in-mold coating process according to claim 8, characterized in that: The preset pressure value is any value between 20 bar and 120 bar.

10. The method for exhausting a coating chamber for an in-mold coating process according to claim 8, characterized in that: The coating temperature is 30° C. to 90° C., and the viscosity is 100 cps to 300 cps.

11. The method for exhausting a coating chamber for an in-mold coating process according to claim 8, characterized in that: The control unit controls the feeding device to feed the coating paint into the coating chamber at a speed of 5 g / min to 700 g / min.

12. The method for exhausting a coating chamber for an in-mold coating process according to claim 8, characterized in that: When the control unit controls the feeding device to convey the coating paint into the coating chamber, the internal temperature of the coating chamber is 80° C. to 130° C.

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