System and method for resin flow front detection during high pressure resin transfer molding of composite parts

Abstract

A system and method for molding a fiber reinforced composite part is disclosed. The system includes a mold having electrical contacts in electrical contact with at least one monitoring circuit incorporated into a fibrous preform disposed in the mold such that a resistance of the monitoring circuit can be monitored as the resin fills the mold cavity and encapsulates the preform. The method includes monitoring a resistance of at least one monitoring circuit incorporated into a fiber preform disposed in a mold to determine a location of a resin flow front as the resin is injected into the mold and around the fiber preform.

Description

[0001] introduce

[0002] The information provided in this section is for the purpose of generally presenting the context of the present disclosure. From the description in this section, the work of the currently named inventors and the aspects of the description that may not constitute prior art at the time of filing should neither be explicitly nor implicitly admitted to be prior art of the present disclosure.

[0003] The present disclosure relates to systems and methods for molding composite parts, and in particular to systems and methods for resin flow front detection during high pressure resin transfer molding of composite parts.

[0004] Some methods of molding composite parts involve injecting resin into a mold cavity containing a fiber preform. Because the mold is closed, the degree of resin filling can be difficult to determine, and as a result, part scrap rates can be relatively high. Summary of the invention

[0005] Embodiments of the present disclosure provide a system for resin flow front detection during resin transfer molding of a composite part. According to a first embodiment, the system includes a part mold having a plurality of mold portions, the mold portions being operable between an open configuration and an operating configuration, in which the mold portions form a mold cavity having an inner surface that is substantially in the shape of the composite part. Preferably, at least one set of electrical contacts is provided on a surface of the mold cavity for electrical contact with at least one monitoring circuit, which may be located within the mold cavity. The monitoring circuit may be incorporated into, but electrically isolated from, a fiber composite part preform, which may be placed into the mold cavity prior to injection of resin. A resistance measurement circuit may be connected to at least one set of electrical contacts on the mold surface to measure the resistance of at least one monitoring circuit in the mold cavity connected to a set of electrical contacts on the mold cavity surface.

[0006] It has been found that as resin is injected into the mold cavity and contacts the monitoring circuit, the resistance of the monitoring circuit changes. The change in resistance of the monitoring circuit, together with information about the mold cavity geometry and the resin flow path and resin properties, enables the location of the resin flow front to be determined during resin transfer molding of a composite part.

[0007] According to a second embodiment of the present disclosure, the system includes a component mold and a fiber component preform disposed therein. The mold may include a plurality of mold portions that together define an internal mold cavity having a surface that substantially corresponds to the shape of the composite component to be manufactured. The component mold may have at least one set of electrical contacts on the inner surface of the component mold. A fiber preform for a composite component is disposed in the mold cavity and includes a plurality of reinforcing fibers and at least one monitoring circuit whose resistance changes as the circuit is surrounded by resin. The at least one monitoring circuit has electrical contacts located on the preform such that when the preform is properly positioned in the mold cavity and the mold is closed, the set of electrical contacts on the component mold contacts the electrical contacts on the at least one monitoring circuit.

[0008] When the electrical contacts on the monitoring circuit in the fiber preform are in electrical contact with at least one set of contacts on the mold surface, the resistance of at least one monitoring circuit can be measured via the at least one set of electrical contacts on the mold surface. The change in the resistance of the monitoring circuit, together with information about the mold cavity geometry and the resin flow path and resin properties, can enable the position of the resin flow front to be determined during resin transfer molding of the composite part.

[0009] Embodiments of the present disclosure also provide a method for resin transfer molding of composite parts, and in particular provide a method for detecting the resin flow front during resin transfer molding of composite parts. According to a third embodiment of the present disclosure, a method for molding a composite part includes inserting a part preform into a mold cavity. The preform includes at least one monitoring circuit whose resistance changes as it is surrounded by resin. The method also includes injecting resin into the mold under pressure and measuring the resistance of the monitoring circuit while injecting the resin. Then, the position of the resin flow front can be estimated at least in part based on the measured resistance of the monitoring circuit. Optionally, one or more parameters of the molding process can be adjusted based on the estimated resin flow front in the mold obtained from the measured resistance data. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present disclosure should be more fully understood from the detailed description and accompanying drawings, in which:

[0011] Figure 1 is a schematic diagram of a composite component preform in a mold as resin is injected into the mold;

[0012] Figure 2 As the resin is injected into Figure 1 A schematic diagram of a composite part preform in a mold after additional resin has been injected into the mold when the mold is shown;

[0013] Figure 3After additional resin has been injected into the mold, Figure 2 A schematic diagram of a composite component preform in a mold when injected into the mold is shown;

[0014] Figure 4 After additional resin has been injected into the mold, Figure 3 A schematic diagram of a composite component preform in a mold when injected into the mold is shown;

[0015] Figure 5 is a schematic diagram of a composite component preform in a mold as resin is injected into the mold;

[0016] Figure 6 After additional resin has been injected into the mold, Figure 5 A schematic diagram of a composite component preform in a mold when injected into the mold is shown;

[0017] Figure 7 After additional resin has been injected into the mold, Figure 6 A schematic diagram of a composite component preform in a mold when injected into the mold is shown;

[0018] Figure 8 is a schematic diagram of a composite component preform in a mold as resin is injected into the mold;

[0019] Fig. 9 After additional resin has been injected into the mold, Figure 8 A schematic diagram of a composite component preform in a mold when injected into the mold is shown;

[0020] Fig.10 After additional resin has been injected into the mold, Fig. 9 A schematic diagram of a composite component preform in a mold when injected into the mold is shown;

[0021] Fig.11 is a schematic diagram showing layers assembled to make a component preform according to the principles of the present disclosure;

[0022] Fig.12 is a schematic diagram showing the assembled layers aligned with a preform mold;

[0023] Fig.13 is a schematic diagram showing the assembled layers being formed by a preform mold;

[0024] Fig.14 is a schematic diagram showing a completed preform in a preform mould;

[0025] Fig.15 is a side view of the completed prefab;

[0026] Fig.16 is a schematic diagram of a component preform located in a bottom portion of an open mold;

[0027] Fig.17 is a schematic diagram of a component preform in a closed mold ready for resin injection;

[0028] Fig.18 is a schematic diagram of a finished component in a closed mold;

[0029] Fig.19 is a schematic diagram of a finished part in an open mold;

[0030] Fig. 20 is a schematic diagram of a monitoring circuit incorporated into a preform, wherein the circuit configuration varies across the preform to provide increasing resolution of the position of the resin flow front toward the end of a fill cycle; and

[0031] Fig.21 is a schematic diagram of multiple monitoring circuits arranged in an overlapping manner to provide a finer resolution of the position of the resin flow front during filling.

[0032] Among the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0033] Embodiments of the present disclosure provide a system for detecting resin flow front during resin transfer molding of a composite part. Figure 16-19 The system 20 includes a component mold 22 having a plurality of mold sections 22 and 24, the mold sections being operable in an open configuration ( Fig.16 , 19 ) or a closed configuration ( Fig.17 , 18 ), wherein the mold portion forms a mold cavity having an inner surface that is generally in the shape of the composite part. To ensure that the part is fully formed, the mold can intentionally include excess volume to accommodate overfill, and the portion can be trimmed to form the final part.

[0034] Preferably, at least one set of electrical contacts 26, 28 is provided on the inner surface of the mold cavity for electrical contact with at least one monitoring circuit, which may be located inside the mold cavity. The monitoring circuit may be incorporated into, but electrically isolated from, a fiber composite component preform 32, which may be placed in the mold cavity before the resin is injected.

[0035] The resistance measurement circuit 30 may be connected to at least one set of electrical contacts 34, 36 to measure the resistance of a monitoring circuit in the mold cavity, which is connected to a set of electrical contacts 26, 28 on the surface of the mold cavity. It has been found that as resin is injected into the mold cavity and contacts the monitoring circuit, the resistance of the monitoring circuit changes. In at least some embodiments, the change (decrease) in resistance is the result of a portion of the monitoring circuit being short-circuited by the injected resin surrounding the portion of the monitoring circuit. The change in resistance of the monitoring circuit may be used alone or in conjunction with other data such as information related to the mold cavity geometry and orientation, the resin flow path, and the resin properties to determine the location of the resin flow front during resin transfer molding of a composite part.

[0036] exist Figure 11-15 The manufacture of the component preform 32 is shown in FIG. Fig.11 As shown, a plurality of layers are assembled. These layers may include carbon fiber mats or scrims 40 and 42, layer 44 including monitoring circuit 30, and layers 46 and 48 for electrically isolating the monitoring circuit from the conductive carbon fiber layer to help ensure that changes in resistance of the monitoring circuit are caused by the presence of the resin and do not contact other supporting layers. These five layers are only a simple illustration of one possible structure, and actual preforms may include additional layers and layers of different materials suitable for the finished part. For example, these layers may also include other materials such as fiberglass, polymers or other suitable materials.

[0037] like Fig.12 As shown, the layers for the preform are aligned with a preform mold 50, which includes a preform mold such as Fig.13 The upper and lower portions shown may be compressed to press the layers together. The layers may be held together mechanically by deformation of the layers, or adhesives may be used to help hold the layers together and / or to help the preform maintain its desired shape. The adhesives may be chemically activated, heat activated, or light activated. As part of the manufacture of the preform 32, electrical contacts, such as contacts 34, 36, electrically connected to at least one monitoring circuit may be formed in or on the surface of the preform. Where multiple monitoring circuits are provided, each monitoring circuit may preferably have its own electrical contacts, which allows the resistance change of each monitoring circuit to be measured separately. The preform mold 50 preferably helps to correctly position the electrical contacts on the preform 32 during assembly, so that when the preform is correctly positioned in its appropriate mold, the contacts on the preform can be aligned with the corresponding contact groups on the mold portion.

[0038] According to a second embodiment of the present disclosure, a system includes a component mold 20 and a fiber component preform 32 disposed therein. The mold may include a plurality of mold sections, such as sections 22 and 24, which together define an internal mold cavity having a surface substantially corresponding to the shape of a composite component to be manufactured. The component mold 20 may have at least one set of electrical contacts 26, 28 on an inner surface of the component mold. A fiber preform 32 for a composite component is disposed in the mold cavity and includes a plurality of reinforcing fibers and at least one monitoring circuit 30, the resistance of which changes as it is surrounded by resin.

[0039] The at least one monitoring circuit 30 may be made of a metal or metal alloy or carbon fiber or other material that provides a measurable resistance within a convenient range. The resistance of the monitoring circuit 30 changes as it is surrounded by resin, which may itself be conductive, causing the resistance to decrease as the resin shorts the path of the monitoring circuit 30 indicating the position of the resin flow front. The monitoring circuit has electrical contacts 34, 36 located on the preform 32 so that a set of electrical contacts 26, 28 on the part mold can contact the electrical contacts 34, 36 on the at least one monitoring circuit when the preform is properly positioned in the mold cavity and the mold is closed. Fig. 20 and 21 As shown, a plurality of monitoring circuits 30 may be provided in the preform, and these circuits and the electrical contacts on the mold are arranged so that the resistance of each circuit 30 may be monitored individually.

[0040] The resistance of at least one monitoring circuit can be measured via at least one set of electrical contacts on the mold when the electrical contacts 34, 46 on the monitoring circuit 30 are in electrical contact with at least one set of contacts 26, 28 on the mold surface. Changes in the resistance of the monitoring circuit 30, along with information about the mold cavity geometry and the resin flow path and properties, can enable the location of the resin flow front to be determined during resin transfer molding of a composite part.

[0041] Embodiments of the present disclosure also provide a method for resin transfer molding composite parts, and in particular provide a method for detecting the resin flow front during resin transfer molding of composite parts. According to a third embodiment of the present disclosure, a method for molding composite parts includes inserting a part preform 32 into a cavity of a mold 20. The preform includes at least one monitoring circuit 30, whose resistance changes as it is surrounded by resin. The method also includes injecting resin into the mold 20 under pressure, and measuring the resistance of one or more monitoring circuits 30 while injecting the resin. Then, the position of the resin flow front during injection can be estimated at least in part based on the measured resistance value of the monitoring circuit. Optionally, one or more parameters of the molding process can be provided, such as the resin injection pressure, the identity of the injection site used, and the volume of resin injected based on feedback of the resin flow front.

[0042] exist Figure 1-4 The operation of the system and method is illustrated in FIG. 1 , wherein a component preform 32 is shown having a monitoring circuit 30 in a generally serpentine configuration. Figure 1 As shown, when the resin flow front 60 has not yet reached the circuit 30, the resistance of the circuit remains unchanged, which means that the front has not advanced to the position where the circuit is located. Figure 2 As shown, once the resin flow front reaches the circuit 30, part of the circuit is shorted, which reduces the resistance of the circuit and indicates that the resin flow front 60 has advanced to the circuit 30. Figure 3 As shown, more circuits 30 are short-circuited and the corresponding resistance decreases, which can indicate that the position of the resin flow front 60 is further advanced. Figure 4 In the process, the resin advances further than Figure 3 The circuit in is shorted more, indicating that filling of the mold is almost complete and the resin flow front 60 has almost fully advanced across the circuit.

[0043] similar, Figure 5-7 The operation of the system and method is also shown in FIG. 3 , where a component preform 32 includes a spiral monitoring circuit 30. The injection point in this example is located at the center of the spiral. Figure 5 As shown in Figure 1, as resin injection begins, the resin begins to surround the center of the spiral, which shorts out the circuit portion in the center of the spiral and reduces the overall resistance of the circuit. This indicates that the resin flow front remains close to the center of the circuit (and the center of the preform in the mold). Figure 6 As shown, continued filling of the mold cavity causes the resin flow front 60 to advance outward from the center of the mold cavity, shorting more of the monitoring circuit 30, thereby reducing the measured resistance value of the monitoring circuit and indicating that the resin flow front is midway between the center and the outer edge of the circuit. Figure 7, the resin flow front 60 has advanced further, and the corresponding decrease in resistance indicates that the resin flow front 60 has approached the outer edge of the circuit.

[0044] similar, Figure 8-10 The operation of the system and method is also shown in FIG. 1 , where a component preform 32 includes four monitoring circuits 30. In this example, the injection point of the resin is located at the center of the preform 32. Figure 8 As shown in Figure 1, before injection begins, the resistance of the circuit remains constant, indicating that injection has not yet begun or at least has not progressed very far. Fig. 9 As shown, the resin flow front 60 has advanced to each circuit 30, and the resistance of each circuit has decreased. This indicates that the resin flow front is still near the center of the circuit (and the center of the preform in the mold). Fig. 9 As shown, continued filling of the mold cavity causes the resin flow front 60 to advance outward from the center of the mold cavity, which shorts more monitoring circuits 30, and the measured resistance of the circuit decreases, indicating that the resin flow front is between the center and the outer edge of the preform. The relative changes in the resistance of the four monitoring circuits indicate the shape of the resin flow front 60. Then, in Fig.10 , the resin flow front 60 advances further toward the edge of the preform 32, and the corresponding decrease in resistance in the four monitoring circuits 30 indicates that the resin flow front 60 is closer to the outer edge of the circuit and the preform.

[0045] like Fig. 20 As shown, as the resin fills the mold cavity from left to right as shown in the figure, in order to provide a finer resolution of the resin flow front, the shape of the monitoring circuit 30 may change, in this case having an increased number of more closely spaced loops.

[0046] like Fig.21 As shown, multiple monitoring circuits 30 may be arranged in an overlapping manner to provide fine resolution of the location of the resin flow front, in this case, resin flowing from right to left into the mold and across the preform 32 .

[0047] Some of the aspects explained above are summarized below by means of numbered examples.

[0048] Example 1. A system for manufacturing a composite part, the system comprising:

[0049] a component mold having a plurality of mold sections operable between an open configuration and an operative configuration in which the mold sections define a mold cavity having a surface substantially in the shape of the composite component;

[0050] at least one set of electrical contacts located on the surface of the mold cavity for electrically contacting a monitoring circuit located inside the mold cavity;

[0051] at least one resistance monitoring circuit electrically connected to at least one set of electrical contacts on the mold cavity surface for measuring the resistance of at least one monitoring circuit connected to at least one set of electrical contacts on the mold cavity surface; and

[0052] A processor is provided for estimating a position of a flow front of resin injected into the mold cavity based at least in part on the resistance measurement of the at least one monitoring circuit.

[0053] Example 2. The system of Example 1, wherein the at least one monitoring circuit is incorporated into a reinforcement preform disposed in the mold.

[0054] Example 3. The system of Example 2, wherein the fiber-reinforced preform includes a barrier layer electrically isolating the at least one monitoring circuit from the fiber-reinforced preform.

[0055] Example 4. The system of Example 2, wherein there are a plurality of monitoring circuits incorporated into the fiber reinforced preform.

[0056] Example 5. The system of Example 4, wherein portions of the plurality of monitoring circuits overlap.

[0057] Example 6. The system of Example 2, wherein the configuration of the monitoring circuit changes the direction of the expected flow of resin in the mold cavity.

[0058] Example 7. A combination of a component mold for resin transfer molding of a composite component, the component mold comprising a plurality of mold portions, the plurality of mold portions together defining an internal cavity, the internal cavity having an inner surface substantially corresponding to the shape of the composite component to be manufactured, the component mold having at least one set of electrical contacts on its surface, a fiber preform for the composite component, the fiber preform comprising a plurality of reinforcing fibers and at least one monitoring circuit, the resistance of the at least one monitoring circuit changing in the presence of resin, the at least one monitoring circuit having electrical contacts positioned on the fiber preform so that when the preform is disposed in the mold cavity, the electrical contacts of the at least one monitoring circuit are in electrical contact with at least one set of electrical contacts on the inner surface of the mold so that the resistance of the at least one monitoring circuit can be measured via the set of electrical contacts on the mold surface.

[0059] Example 8. The combination of Example 7, wherein the fiber preform further comprises a barrier layer electrically isolating the at least one monitoring circuit from the fiber preform.

[0060] Example 9. The combination of Example 7, wherein the fiber preform comprises a plurality of monitoring circuits.

[0061] Example 10. The combination of Example 9, wherein portions of the plurality of monitoring circuits overlap.

[0062] Example 11. A combination of Example 7, wherein the configuration of the monitoring circuit changes the expected flow direction of the resin in the mold cavity.

[0063] Example 12. A method of molding a fiber reinforced composite part, the method comprising the steps of:

[0064] inserting a fiber preform into a mold cavity, the preform including at least one monitoring circuit having a resistance that changes as the preform is surrounded by resin;

[0065] The resin is injected into the mold under pressure;

[0066] measuring a resistance of the at least one monitoring circuit; and

[0067] The measured resistance data is used to estimate the position of the resin flow front in the mold.

[0068] Example 13. The method of Example 12, further comprising changing at least one parameter of the molding process in response to the estimated position of the resin flow front.

[0069] Example 14. A method according to Example 12, wherein the mold has at least first and second electrical contacts, and wherein the at least one monitoring circuit has first and second electrical contacts positioned on the preform to engage with the first and second electrical contacts on the mold, and wherein the resistance of the monitoring circuit is measured by measuring the resistance between the first and second electrical contacts on the mold.

[0070] Example 15. The method of Example 12, wherein the fiber preform comprises a plurality of monitoring circuits.

[0071] Example 16. The method of Example 15, wherein at least some of the plurality of monitoring circuits at least partially overlap with each other.

[0072] Example 17. The method of Example 12, wherein the configuration of the monitoring circuit changes the expected flow direction of the resin.

[0073] Example 18. The method of Example 12, wherein the step of estimating the position of the resin flow front is based in part on at least one of a geometry of the mold, flow properties of the resin, and an expected flow direction of the resin in the mold.

[0074] The foregoing description is essentially illustrative only, and there is no intention to limit the present disclosure, its application or use. The broad teachings of the present disclosure can be implemented in various forms. Therefore, although the present disclosure includes specific examples, the true scope of the present disclosure should not be limited thereto, because after studying the drawings, the specification and the appended claims, other modifications will become apparent. It should be understood that one or more steps in the method can also be performed in different orders (or simultaneously) without changing the principles of the present disclosure. In addition, although each of the embodiments is described above as having certain features, any one or more of those features described with reference to any embodiment of the present invention can also be implemented in the features of any one of the other embodiments and / or combined with the features of any one of the other embodiments, even if the combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and the replacement of one or more embodiments with each other remains within the scope of the present disclosure.

[0075] Various terms are used to describe the spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.), including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "above," "below," and "disposed." Unless explicitly described as "direct," when a relationship between a first and a second element is described in the above disclosure, the relationship can be a direct relationship in which there are no other intervening elements between the first and second elements, but can also be an indirect relationship in which there are one or more intervening elements (spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be interpreted to mean a logical (A or B or C) using a non-exclusive logical "or," and should not be interpreted to mean "at least one of A, at least one of B, and at least one of C."

Claims

1. A system for manufacturing a composite component, the system comprising: a component mold having a plurality of mold sections operable between an open configuration and an operative configuration in which the mold sections define a mold cavity having a surface substantially in the shape of the composite component; at least one set of electrical contacts located on the surface of the mold cavity for electrically contacting a monitoring circuit located inside the mold cavity; at least one resistance monitoring circuit electrically connected to at least one set of electrical contacts on the mold cavity surface for measuring the resistance of at least one monitoring circuit connected to at least one set of electrical contacts on the mold cavity surface; as well as A processor is provided for estimating a position of a flow front of resin injected into the mold cavity based at least in part on the resistance measurement of the at least one monitoring circuit.

2. The system according to claim 1, wherein: The at least one monitoring circuit is incorporated into a reinforcement preform disposed in the mould.

3. The system according to claim 2, wherein: The fiber reinforced preform includes a barrier layer electrically isolating the at least one monitoring circuit from the fiber reinforced preform.

4. The system according to claim 2, wherein: There are a plurality of monitoring circuits incorporated into the fiber reinforced preform.

5. The system according to claim 4, wherein: Portions of the plurality of monitoring circuits overlap.

6. A method of molding a fiber reinforced composite component, the method comprising the steps of: inserting a fiber preform into a mold cavity, the preform including at least one monitoring circuit having a resistance that changes as the preform is surrounded by resin; The resin is injected into the mold under pressure; measuring a resistance of the at least one monitoring circuit; and The measured resistance data is used to estimate the position of the resin flow front in the mold. 7 . The method of claim 6 , further comprising changing at least one parameter of the molding process in response to the estimated position of the resin flow front.

8. The method according to claim 6, wherein: The mold has at least first and second electrical contacts, and wherein the at least one monitoring circuit has first and second electrical contacts positioned on the preform to engage the first and second electrical contacts on the mold, and wherein the resistance of the monitoring circuit is measured by measuring the resistance between the first and second electrical contacts on the mold.

9. The method according to claim 6, wherein: The fiber preform includes a plurality of monitoring circuits.

10. The method according to claim 9, wherein: At least some of the plurality of monitoring circuits at least partially overlap with each other.

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