High-performance low-cost vacuum forming device and forming process for composite material structure

Abstract

The invention belongs to the technical field of resin-based composite material forming, and particularly relates to a high-performance low-cost vacuum forming device for a composite material structure and a forming process, and the high-performance low-cost vacuum forming device for the composite material structure comprises an operation platform; the heating part is fixedly connected to the operation platform, a composite material workpiece is placed on the top face of the heating part, and the heating part is used for heating the composite material workpiece; the vacuum part covers the top of the composite material workpiece; the rolling part is positioned above the vacuum part and is used for rolling the composite material workpiece in the vacuum part in a reciprocating manner; the resin injection part is communicated with the middle part of a cavity defined by the vacuum part and the heating part; and the resin negative pressure recycling assemblies communicate with the edge of a cavity defined by the vacuum part and the heating part, the multiple resin negative pressure recycling assemblies are symmetrically distributed on the two sides of the heating part, and the high-performance and low-cost vacuum forming process of the composite material structure is provided. The forming quality of the composite material can be improved while the cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of resin-based composite material molding, and in particular relates to a high-performance and low-cost vacuum molding device and molding process for a composite material structure. Background Art

[0002] Composite materials have excellent specific strength, specific stiffness and other characteristics. They are widely used in aerospace, rail transportation, shipbuilding and ocean industries. The demand for their application is also gradually increasing, which has also attracted people's attention to the composite material molding process.

[0003] The most widely used composite material forming processes at present are autoclave forming and vacuum-assisted resin injection process. The autoclave forming process is stable and reliable, but the autoclave equipment is expensive and the process cost is high. Moreover, as the size of the part increases, the cost of a large autoclave increases exponentially, and the later maintenance cost of the autoclave is also high. The vacuum-assisted resin injection process is a relatively new low-cost composite material forming technology that improves the forming production efficiency of composite materials. However, when the resin infiltrates the fiber, some local permeability changes and unreasonable layout of the guide tube lead to dry spots and dry areas after the part is cured. The resin will produce a pressure gradient during the flow process, resulting in uneven thickness of the part, making it difficult to ensure a uniform and constant fiber volume fraction. During the forming process, the preform is only subjected to one atmospheric pressure, resulting in a low fiber volume fraction of the formed part, which in turn affects the mechanical properties of the structure. Therefore, there is an urgent need for a high-performance and low-cost vacuum forming device for composite structure to solve the problem. Summary of the invention

[0004] The purpose of the present invention is to provide a high-performance and low-cost vacuum forming device for composite material structures to solve the above problems.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A high-performance and low-cost vacuum forming device for composite material structure, comprising:

[0007] Operating platform;

[0008] A heating part, fixedly connected to the operating platform, a composite material part is placed on the top surface of the heating part, and the heating part is used to heat the composite material part;

[0009] A vacuum portion, covering the top of the composite material part;

[0010] A rolling part, located above the vacuum part, for reciprocatingly rolling the composite material part in the vacuum part;

[0011] A resin injection part, connected to the middle of the cavity surrounded by the vacuum part and the heating part;

[0012] The resin negative pressure recovery component is communicated with the edge of the cavity surrounded by the vacuum part and the heating part. The resin negative pressure recovery component is provided with a plurality of components, which are symmetrically distributed on both sides of the heating part.

[0013] Preferably, the heating unit comprises a heating platform, and the heating platform is fixedly connected to the operating platform.

[0014] Preferably, the vacuum part comprises a vacuum bag, the vacuum bag covers the top surface of the composite material part, and the edge of the vacuum bag is fixed on the heating platform.

[0015] Preferably, the rolling part comprises two symmetrically arranged circulating rolling devices, wherein the circulating rolling devices are located above the vacuum bag, the circulating rolling devices are transmission-connected with rollers, and the outer walls of the rollers abut against the top surface of the vacuum bag.

[0016] Preferably, the resin injection part comprises a resin barrel, and the resin barrel is connected with the middle part of the inner side of the cavity surrounded by the vacuum bag and the heating platform through a pipeline.

[0017] Preferably, the resin negative pressure recovery assembly comprises a resin collecting barrel, one side of which is connected to the edge of the cavity surrounded by the vacuum bag and the heating platform, and the other end of which is connected to the vacuum part;

[0018] A capillary absorption part is arranged at the bottom of the heating platform, a liquid inlet end of the capillary absorption part is communicated with the inside of the cavity surrounded by the vacuum bag and the heating platform, and a liquid outlet end of the capillary absorption part is communicated with the resin collection barrel.

[0019] Preferably, the vacuum part comprises a vacuum pump, and an air inlet end of the vacuum pump is connected to one side of the top of the resin collecting barrel.

[0020] Preferably, the capillary absorption part includes a plurality of resin guide holes, the plurality of resin guide holes are arranged in a matrix, the plurality of resin guide holes are opened on the heating platform, and the plurality of resin guide holes are connected to the resin collection barrel through pipelines.

[0021] A high-performance and low-cost vacuum forming process for composite material structure, based on the above-mentioned high-performance and low-cost vacuum forming device for composite material structure, comprises the following steps:

[0022] Step 1: Apply a release agent; clean the heating part with acetone in advance to remove impurities, and after the heating part is cleaned, evenly apply the release agent to the surface of the heating part, and repeat 3-5 times;

[0023] Step 2: Laying the fiber cloth layer and auxiliary materials on the heating part;

[0024] Step 3: Connect the device and vacuum pump; First, connect the device in order, cover the vacuum part on the fiber cloth layer and auxiliary materials of the heating part, connect the vacuum port of the vacuum part with the resin negative pressure recovery component, and check the sealing; connect the resin filling port on the heating part with the resin injection part. Open the resin negative pressure recovery component, carefully check the sealing of the vacuum part during the vacuum pumping process, and seal it with sealing tape if there is leakage;

[0025] Step 4: Infiltration with resin and pressurization. After the air in the vacuum part is extracted, the resin injection part is opened to start the resin infiltration, and then the heating part and the rolling part are started. The roller of the rolling part applies cyclic pressure on the vacuum part to squeeze the resin to fully impregnate the fiber cloth and drive the excess resin into the resin negative pressure recovery component.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] When in use, the composite material part is placed on the heating part, and then the vacuum part is covered on the top of the composite material part, and the edge of the vacuum part is fixed and sealed to the heating part, and the composite material part is heated by the heating part. At the same time, the resin negative pressure recovery component is started to exhaust the vacuum of the cavity surrounded by the vacuum part and the heating part. In the process of exhausting the vacuum, due to the negative pressure, the resin in the resin injection part will be sucked into the cavity surrounded by the vacuum part and the heating part, and diffused on the surface of the composite material part. At the same time, the rolling part is started to roll the surface of the composite material part to make the resin evenly distributed and the resin evenly penetrated downward, and the excess resin enters the resin negative pressure recovery component. The device makes the resin distribution more even by setting the rolling part and the resin negative pressure recovery component, and can realize the hot pressing function without the need for an autoclave, thereby reducing costs and improving the quality of composite material molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0029] Figure 1 It is a schematic diagram of the structure of the present invention;

[0030] Figure 2 This is a process flow chart of rolling heating forming of the present invention;

[0031] Figure 3The tensile modulus and its corresponding fiber volume fraction are plotted against the holding pressure of the present invention;

[0032] Figure 4 This is a graph showing the change in tensile strength of the sample of the present invention with the holding pressure;

[0033] Figure 5 This is a graph showing the change of interlaminar shear strength with the holding pressure of the present invention;

[0034] Figure 6 is a graph showing the thickness and fiber volume fraction of the glass fiber laminate of the present invention as a function of the holding time;

[0035] Figure 7 The tensile modulus and its corresponding fiber volume fraction are plotted against the dwell time of the present invention;

[0036] Figure 8 The change of tensile strength of the sample of the present invention with the holding time;

[0037] Fig. 9 The interlaminar shear strength of the present invention varies with the holding time;

[0038] Among them, 1. roller; 2. circulating rolling device; 3. vacuum bag; 4. heating table; 5. composite material parts; 6. resin guide holes; 7. operating platform; 8. vacuum pump; 9. resin collection barrel; 10. resin barrel. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Embodiment 1:

[0042] Reference Figure 1 This embodiment discloses a high-performance and low-cost vacuum forming device for composite material structure, comprising:

[0043] Operating platform 7;

[0044] A heating part is fixedly connected to the operating platform 7, a composite material part 5 is placed on the top surface of the heating part, and the heating part is used to heat the composite material part 5;

[0045] A vacuum portion, covering the top of the composite material part 5;

[0046] A rolling part, located above the vacuum part, for reciprocatingly rolling the composite material part 5 in the vacuum part;

[0047] A resin injection portion communicated with a middle portion of a cavity surrounded by the vacuum portion and the heating portion;

[0048] The resin negative pressure recovery component is communicated with the edge of the cavity surrounded by the vacuum part and the heating part. There are multiple resin negative pressure recovery components, which are symmetrically distributed on both sides of the heating part.

[0049] When in use, the composite material part 5 is placed on the heating part, and then the vacuum part is covered on the top of the composite material part 5, and the edge of the vacuum part is fixed and sealed to the heating part, and the composite material part 5 is heated by the heating part. At the same time, the resin negative pressure recovery component is started to exhaust the vacuum in the cavity surrounded by the vacuum part and the heating part. In the process of exhausting the vacuum, due to the negative pressure, the resin in the resin injection part will be sucked into the cavity surrounded by the vacuum part and the heating part, and diffused on the surface of the composite material part 5. At the same time, the rolling part is started to roll the surface of the composite material part 5 to make the resin evenly distributed and the resin evenly penetrate downward, and the excess resin enters the resin negative pressure recovery component. The device makes the resin distribution more even by setting the rolling part and the resin negative pressure recovery component, and can realize the hot pressing function without the need for an autoclave, thereby reducing costs and improving the quality of composite material molding.

[0050] According to a further optimized solution, the heating part includes a heating platform 4 , and the heating platform 4 is fixedly connected to the operating platform 7 .

[0051] According to a further optimized solution, the vacuum part includes a vacuum bag 3 , which covers the top surface of the composite material part 5 , and the edge of the vacuum bag 3 is fixed on the heating platform 4 .

[0052] According to a further optimization scheme, the rolling part includes two symmetrically arranged circulating rolling devices 2, which are located above the vacuum bag 3. The circulating rolling device 2 is transmission-connected to the roller 1, and the outer wall of the roller 1 abuts against the top surface of the vacuum bag 3.

[0053] According to a further optimized solution, the resin injection part includes a resin barrel 10, and the resin barrel 10 is connected to the middle part of the inner side of the cavity surrounded by the vacuum bag 3 and the heating platform 4 through a pipeline.

[0054] Further optimizing the scheme, the resin negative pressure recovery assembly includes a resin collecting barrel 9, one side of the resin collecting barrel 9 is connected to the edge of the cavity surrounded by the vacuum bag 3 and the heating table 4, and the other end of the resin collecting barrel 9 is connected to the vacuum part;

[0055] A capillary absorption part is provided at the bottom of the heating platform 4 , the liquid inlet end of the capillary absorption part is connected to the inside of the cavity surrounded by the vacuum bag 3 and the heating platform 4 , and the liquid outlet end of the capillary absorption part is connected to the resin collection barrel 9 .

[0056] According to a further optimized solution, the vacuum part includes a vacuum pump 8 , and an air inlet end of the vacuum pump 8 is connected to one side of the top of the resin collecting barrel 9 .

[0057] According to a further optimized solution, the capillary absorption part includes a plurality of resin guide holes 6 , which are arranged in a matrix. The resin guide holes 6 are opened on the heating platform 4 , and the plurality of resin guide holes 6 are connected to the resin collecting barrel 9 through pipelines.

[0058] The present invention provides a high-performance and low-cost vacuum forming device for composite material structure, which is mainly composed of a heating platform 4, a circulating rolling device 2, a vacuum pump 8, a resin barrel 10, a resin collecting barrel 9, etc. The specific operation steps are: remove the circulating rolling device 2 from the heating platform 4, lay the composite material part 5 on the heating platform 4, and then seal it with a vacuum bag 3; connect the resin injection hole above the vacuum bag 3 to the conduit of the resin barrel 10; connect the conduits of the resin collecting barrel 9 on both sides of the vacuum bag 3; move the circulating rolling device 2 to the top of the composite material part 5 on the heating platform 4; first, vacuumize to ensure that there is no air in the vacuum bag 3, then turn on the switch of the resin barrel 10 to allow the resin to be injected into the vacuum bag 3, and then set the temperature parameters of the heating platform 4 and the pressure parameters of the circulating rolling device 2 and turn on the device switches respectively.

[0059] After the resin is injected into the vacuum bag 3, the rollers of the circulating rolling device 2 can drive the resin to spread to both sides. The resin guide holes 6 on the heating table 4 will attract the resin to penetrate downward under the action of capillary action and negative pressure. At the same time, the vacuum pump 8 will also pump excess resin into the resin collection barrel 9.

[0060] The present invention proposes to use physical pressure instead of air pressurization, which can effectively reduce the requirements and costs for the molding device. At the same time, a number of resin guide holes 6 arranged in a matrix at the bottom of the heating table 4 can produce "capillary action", which attracts the resin to flow downward. Each resin guide hole 6 is connected to the resin collection barrel 9 through a pipeline. Under the action of the vacuum pump 8, the "capillary action" effect can be improved. Finally, the excess resin is collected in the resin collection barrel 9 through the guide pipe.

[0061] The capillary force formula of the "capillary action" used is:

[0062]

[0063] Where F represents the capillary force, η represents the viscosity of the resin, r represents the radius of the resin flow hole, and L represents the length of the flow hole.

[0064] The circulating rolling device 2 is mainly composed of an annular guide rail and a roller 1 with relatively large rigidity. The roller 1 circulates along the guide rail. When the roller 1 is in the lower half of the guide rail, it presses on the composite material part 5 with a certain pressure and rolls to both sides along the center of the composite material part 5. This not only applies a certain pressure to the composite material part 5, but also squeezes the resin injected in the upper part of the composite material part 5 to both sides, which helps to spread the resin evenly and improves the performance and uniformity of the composite material part 5.

[0065] When roller 1 moves to both sides, it moves to the upper part along the guide rail. During this process, roller 1 has no force on the composite material until it moves to the middle part again. Roller 1 rolls cyclically along the guide rail, replacing the autoclave to realize the hot pressing process, and can also effectively promote the diffusion and impregnation of resin. A vacuum bag 3 is laid on the composite material part 5. A hole is opened in the center of the vacuum bag, which is connected to the resin barrel 10 through a conduit for injecting resin into the composite material part 5.

[0066] Both sides of the vacuum bag 3 are connected to the resin collection barrel 9 through conduits, and the resin collection barrel 9 is also connected to a vacuum pump 8 for evacuating the vacuum bag 3 and driving excess resin to flow into the resin collection barrel 9. In addition, the diversion pipe below the resin diversion hole 6 is also connected to the conduit leading to the resin collection barrel 9.

[0067] Embodiment 2:

[0068] refer to Figures 2 to 9 This embodiment is a high-performance and low-cost vacuum forming process for a composite material structure based on Embodiment 1, and a high-performance and low-cost vacuum forming device for a composite material structure based on the above-mentioned method, including the following steps:

[0069] Step 1: Apply release agent; clean the heating part with acetone in advance to remove impurities, and then evenly apply the release agent to the surface of the heating part after the heating part is cleaned, and repeat 3-5 times;

[0070] The heating platform 4 is cleaned with acetone in advance to remove impurities. After the heating platform 4 is cleaned, the release agent is evenly applied to the surface of the heating platform 4, and the process is repeated 3-5 times.

[0071] Step 2: Lay the fiber cloth layer and auxiliary materials on the heating part;

[0072] The fiber cloth is first laid on the heating table 4, and then the release cloth, isolation film, guide net and other process auxiliary materials are laid. The area of ​​the release cloth and the isolation film should cover the fiber cloth, and the isolation film should be exposed at one end of the guide net to ensure that the resin can fully infiltrate the glass fiber.

[0073] Step 3: Connect the device and vacuum pump; First, connect the device in order, cover the vacuum part on the fiber cloth layer and auxiliary materials of the heating part, connect the vacuum port of the vacuum part with the resin negative pressure recovery component, and check the sealing; connect the resin filling port on the heating part with the resin injection part. Open the resin negative pressure recovery component, and carefully check the sealing of the vacuum part during the vacuum pumping process. If there is leakage, seal it with sealing tape;

[0074] First, connect the devices in order. After covering the vacuum bag 3 on the heating table 4, connect the vacuum port of the vacuum bag 3 to the resin collection bucket 9, and then connect the resin collection bucket 9 to the vacuum pump 8 and check the sealing. Connect the air filling port of the heating table 4 to the air pump to provide pressure. Connect the resin filling port on the heating table 4 to the resin bucket 10. Then turn on the vacuum pump 8. During the vacuuming process, carefully check that there is no leakage in every part of the vacuum bag 3. If leakage is found, seal it with sealing tape.

[0075] Step 4: Resin impregnation and pressurization. After the air in the vacuum part is extracted, open the resin injection part to start resin impregnation, and then start the heating part and the rolling part. The roller of the rolling part applies cyclic pressure on the vacuum part to squeeze the resin to fully impregnate the fiber cloth and drive the excess resin into the resin negative pressure recovery component.

[0076] After the air in the vacuum bag 3 is completely extracted, the valve connected to the resin barrel 10 is opened to start the resin infiltration, and then the heating table 4 and the circulating rolling device 2 are started. The roller of the circulating rolling device 2 applies circulating pressure on the fiber cloth, squeezes the resin to fully impregnate the fiber cloth, and drives excess resin into the resin barrel 10.

[0077] refer to Figure 2 The process flow of this embodiment is as follows: first, the fiber cloth is cut and laid to complete the process packaging; the resin and the curing agent are mixed according to the specified ratio, and the resin is infiltrated by vacuum. After the resin is fully infiltrated, the heating table 4 and the circulating rolling device 2 are started. The roller of the circulating rolling device 2 rolls cyclically above the fiber cloth, applies a certain pressure to the fiber cloth and removes excess resin, thereby increasing the fiber volume fraction of the workpiece. Finally, the curing reaction of the resin is completed according to the temperature process curve.

[0078] refer to Figures 3 to 9It can be seen that compared with the traditional vacuum-assisted resin injection process, this combined process can provide greater molding process pressure, squeeze out excess resin, increase the fiber volume fraction of the product, and thus improve the mechanical properties of the product. In addition, the resin infiltration process can be heated using a heating platform without the need for expensive autoclave devices, which reduces costs and is also beneficial to the infiltration molding of high-viscosity resins. Compared with the traditional autoclave process, the raw materials are fiber preforms and resins rather than expensive prepregs, and the packaging auxiliary materials are relatively simple, which is beneficial to reducing manufacturing costs.

[0079] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0080] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A high-performance and low-cost vacuum forming device for composite material structure, characterized in that: include: Operating platform (7); A heating part, fixedly connected to the operating platform (7), a composite material part (5) being placed on the top surface of the heating part, and the heating part being used to heat the composite material part (5); A vacuum portion, covering the top of the composite material part (5); A rolling section, located above the vacuum section, for reciprocatingly rolling the composite material product (5) in the vacuum section; A resin injection part, connected to the middle of the cavity surrounded by the vacuum part and the heating part; The resin negative pressure recovery component is communicated with the edge of the cavity surrounded by the vacuum part and the heating part. The resin negative pressure recovery component is provided with a plurality of components, which are symmetrically distributed on both sides of the heating part.

2. A high-performance and low-cost vacuum forming device for composite material structure according to claim 1, characterized in that: The heating part comprises a heating platform (4), and the heating platform (4) is fixedly connected to the operating platform (7).

3. A high-performance and low-cost vacuum forming device for composite material structure according to claim 2, characterized in that: The vacuum part comprises a vacuum bag (3), the vacuum bag (3) covers the top surface of the composite material part (5), and the edge of the vacuum bag (3) is fixed on the heating platform (4).

4. A high-performance and low-cost vacuum forming device for composite material structure according to claim 3, characterized in that: The rolling section comprises two symmetrically arranged circulating rolling devices (2), wherein the circulating rolling devices (2) are located above the vacuum bag (3), and the circulating rolling devices (2) are drivingly connected to a roller (1), wherein an outer wall of the roller (1) abuts against a top surface of the vacuum bag (3).

5. A high-performance and low-cost vacuum forming device for composite material structure according to claim 3, characterized in that: The resin injection part comprises a resin barrel (10), and the resin barrel (10) is connected to the middle part of the inner side of the cavity surrounded by the vacuum bag (3) and the heating platform (4) through a pipeline.

6. A high-performance and low-cost vacuum forming device for composite material structure according to claim 3, characterized in that: The resin negative pressure recovery assembly comprises a resin collection barrel (9), one side of the resin collection barrel (9) is connected to the edge of a cavity surrounded by the vacuum bag (3) and the heating platform (4), and the other end of the resin collection barrel (9) is connected to a vacuum part; A capillary absorption part is provided at the bottom of the heating platform (4); a liquid inlet end of the capillary absorption part is connected to the interior of a cavity surrounded by the vacuum bag (3) and the heating platform (4); and a liquid outlet end of the capillary absorption part is connected to the resin collection barrel (9).

7. A high-performance and low-cost vacuum forming device for composite material structure according to claim 6, characterized in that: The vacuum part comprises a vacuum pump (8), and an air inlet end of the vacuum pump (8) is connected to one side of the top of the resin collecting barrel (9).

8. A high-performance and low-cost vacuum forming device for composite material structure according to claim 6, characterized in that: The capillary absorption part comprises a plurality of resin guide holes (6), the plurality of resin guide holes (6) are arranged in a matrix, the plurality of resin guide holes (6) are opened on the heating platform (4), and the plurality of resin guide holes (6) are connected to the resin collection barrel (9) through pipelines.

9. A high-performance and low-cost vacuum forming process for composite material structures, based on a high-performance and low-cost vacuum forming device for composite material structures according to any one of claims 1 to 8, characterized in that: The steps include: Step 1: Apply a release agent; clean the heating part with acetone in advance to remove impurities, and after the heating part is cleaned, evenly apply the release agent to the surface of the heating part, and repeat 3-5 times; Step 2: Laying the fiber cloth layer and auxiliary materials on the heating part; Step 3: Connect the device and vacuumize; first, connect the devices in order, cover the vacuum part on the fiber cloth layer and auxiliary materials of the heating part, connect the vacuum port of the vacuum part with the resin negative pressure recovery component, and check the sealing; connect the resin filling port on the heating part with the resin injection part, open the resin negative pressure recovery component, and carefully check the sealing of the vacuum part during the vacuuming process, and seal it with sealing tape if there is leakage; Step 4: Infiltration with resin and pressurization. After the air in the vacuum part is extracted, the resin injection part is opened to start the resin infiltration, and then the heating part and the rolling part are started. The roller of the rolling part applies cyclic pressure on the vacuum part to squeeze the resin to fully impregnate the fiber cloth and drive the excess resin into the resin negative pressure recovery component.

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