Helicopter rotor blade filling foam mold pressing allowance control method and rotor blade
By precisely controlling the foam molding allowance and the surface coating resin, the problem of poor bonding performance at the helicopter rotor blade interface was solved, and high-performance rotor blade manufacturing was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-03-27
AI Technical Summary
Existing technologies struggle to effectively control the molding allowance of foam filling in helicopter rotor blades, resulting in poor interfacial adhesion and impacting blade quality and lifespan.
By precisely controlling the molding allowance of the filling foam and coating the surface of the filling foam with the skin resin, and combining the elastic compression properties of the filling foam material, the appropriate allowance surface is determined to ensure high-quality bonding between the filling foam and the skin.
This improved the bonding strength of the rotor blades, avoiding vibration problems caused by poor bonding, and enhancing the manufacturing quality and lifespan of the blades.
Smart Images
Figure CN121733828A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of foam filling and molding co-curing of helicopter rotor blades, and particularly relates to a method for controlling the residual amount of foam filling and molding of a helicopter rotor blade and a rotor blade. BACKGROUND
[0002] The foam filling and molding co-curing technology of a helicopter rotor blade is mainly used for the production of a rotor blade. The technology realizes lightweight, structural reinforcement and performance optimization of the rotor blade by filling a tilting foam material into the interior of the rotor blade, thereby forming an integrated high-performance structure.
[0003] The core of the technology is to fill the foam material into the internal cavity of the rotor blade, and to make the rotor blade skin (usually composed of composite materials) and the foam core tightly combined through mold pressurization and heating curing.
[0004] There are generally two ways of filling foam forming, one is to preform the foam core. The foam core cut into shape in advance is embedded into the cavity of the rotor blade. The other is in-situ foaming. Liquid foaming material is injected into the cavity, and it is expanded and filled into the entire cavity through heating or chemical reaction.
[0005] Common filling foam materials for helicopter rotor blades mainly include polyurethane (PU) foam, polyvinyl chloride (PVC) foam and polymethyl methacrylimide (PMI) foam, etc. The main challenge of the manufacturing process of the preformed filling foam of the helicopter rotor blade is the interface bonding performance.
[0006] The airfoil structure of the helicopter rotor blade is mainly composed of a spar, a skin and a filling foam, wherein the spar is located at the leading edge, and the trailing edge is basically composed of the skin and the filling foam. In order to improve the molding quality of the rotor blade, the size of the filling foam is higher than the theoretical size, and the foam exceeding the theoretical size is called filling foam molding residual amount. If the filling foam molding residual amount is too small, it cannot provide the bonding quality; if the filling foam molding residual amount is too large, the filling foam will be crushed during the molding of the rotor blade. Therefore, the molding residual amount of the filling foam must be selected appropriately.
[0007] At present, the interface bonding performance of the filling foam of the helicopter rotor blade mainly relies on the method of controlling the filling foam molding residual amount. The filling foam molding residual amount control method generally adopts a fixed value. The adhesive interface between the filling foam and the skin is completely bonded by the resin of the composite skin. SUMMARY
[0008] The purpose of the present application is: By precisely controlling the filling foam molding residual amount of the helicopter rotor blade and the pretreatment method of the adhesive interface between the filling foam and the skin, the bonding strength of the skin and the filling foam is improved, and the high-performance quality manufacturing of the helicopter rotor blade is realized.
[0009] The technical solution of this invention is: To achieve the above-mentioned objective, according to a first aspect of the present invention, a method for controlling the molding allowance of filling foam for helicopter rotor blades is provided, wherein the molding allowance of filling foam is controlled according to the compression performance index of filling foam used for rotor blades as its thickness varies.
[0010] The specific steps are as follows: Step 1: Determine the type of foam material used to fill the helicopter rotor blades; Step 2: Based on the theoretical numerical model of the foam filling for helicopter rotor blades, determine the range of foam material thickness and accordingly determine the thickness value of the test block for the elastic compression performance of the foam material. Step 3: Prepare a test block for the elastic compression performance of the foam-filled material based on the thickness value of the test block determined in Step 2. Step 4: Test the elastic compression range of the foam material sample block to obtain the compression performance curve of the foam material; Step 5: Divide the theoretical numerical model of the foam filling and determine the fitting point of the foam allowance; Step 6: Fit the surface to fill the remaining foam. Step 7: Combine the theoretical numerical model of the filling foam and the numerical model of the foam margin.
[0011] In one possible embodiment, in step two, the thickness value of the test block for the elastic compression performance of the foam-filled material is determined as follows: the maximum and minimum theoretical thickness values of the theoretical numerical model of the foam-filled material are measured, and n thickness values are inserted at equal intervals between the maximum and minimum values. These n values, together with the maximum and minimum values, are used as the thickness values of the test block for measuring the elastic compression performance of the foam-filled material.
[0012] In one possible embodiment, in step three, the sample block is a hexahedral solid shape, and the thickness value of the sample block determined in step two is used as the height of the sample block. The length and width dimensions of the sample block are equal. The length and width dimensions of the sample block can be determined according to the maximum thickness value. The selection of the length and width dimensions of the sample block should ensure that the sample block will not become unstable under pressure in the thickness direction.
[0013] In one possible embodiment, in step three, multiple sample blocks of the same size should be made, and the average value should be taken when testing performance.
[0014] In one possible embodiment, in step five, the theoretical numerical model of the helicopter rotor blade filling foam is extracted and divided into multiple cross-sections along the spanwise direction at equal intervals; on each cross-section, the thickness line of the filling foam is marked along the chordwise direction at equal intervals, and the endpoint of this thickness line is used as the starting point for fitting the foam allowance.
[0015] In one possible embodiment, in step six, based on the theoretical thickness lines at different positions of the theoretical model of the filled foam determined in step five, and referring to the compression performance curve of the filled foam material determined in step four, the maximum allowable size of the foam at that position is obtained. This maximum allowable size is then multiplied by a safety factor to obtain the applicable allowable size of the foam at that position. The safety factor ranges from 0.6 to 0.9. Based on this size, the thickness points at that position after adding the applicable allowable size are plotted. The thickness points on the same cross-section after adding the applicable allowable size are fitted into an applicable allowable curve, and then the applicable allowable curve is fitted into a foam allowable surface.
[0016] The allowance surface for filling foam can be extended to one side of the theoretical model of filling foam, or the allowance value can be divided into two parts, and the acceptance can be carried out on both sides of the theoretical model of filling foam according to the divided allowance value.
[0017] In one possible embodiment, in step seven, the foam allowance surface generated in step six is used as the thickness direction shape of the theoretical model of the foam allowance to form a model with allowance for manufacturing rotor blade foam.
[0018] In one possible embodiment, to ensure high-quality adhesion between the filler foam and the rotor blade skin, a thin layer of resin adhesive is applied to the surface of the filler foam. This resin adhesive must be thin enough to effectively fill the pores of the foam. The resin adhesive should be compatible with the resin system of the matrix material used for the rotor blade skin.
[0019] According to a second aspect of the present invention, a rotor blade is provided, employing the above-described method for controlling the foam molding allowance of a helicopter rotor blade.
[0020] The advantages of this invention are: This invention rationally determines the molding allowance for the filling foam of helicopter rotor blades, enabling it to truly utilize the molding technology that enhances the internal filling and skin performance without damaging the filling foam. With the help of the interface filler adhesive, it ensures that the blade will not vibrate due to poor adhesion between the filling foam and the skin during its lifespan. Attached Figure Description
[0021] To more clearly illustrate the technical solutions implemented in this invention, the accompanying drawings used in the embodiments of this invention will be briefly explained below. Obviously, the drawings described below are merely some embodiments of this invention. Those skilled in the art can obtain other drawings based on these drawings without any creative effort.
[0022] Figure 1 Schematic diagram of a sample block of foam material filling helicopter rotor blades.
[0023] Figure 2 A schematic diagram of the compression performance curve of the foam material used to fill helicopter rotor blades.
[0024] Figure 3 A schematic diagram of the theoretical digital model segmentation of the foam filling for helicopter rotor blades.
[0025] Figure 4 Schematic diagram of the extended foam margin at each fitting point of the theoretical numerical model of foam filling for helicopter rotor blades.
[0026] Figure 5 A schematic diagram of the profile margin curve of each fitting point in the theoretical numerical model of the helicopter rotor blade filled with foam.
[0027] Figure 6 A schematic diagram of the fitting curves and refitted profile margin surfaces of the theoretical numerical model of foam filling for helicopter rotor blades.
[0028] Figure 7 A practical digital model diagram of foam filling for helicopter rotor blades.
[0029] Figure 8 Flowchart of the method for fabricating a digital model of the foam allowance for filling helicopter rotor blades.
[0030] (1) is the sample block of the rotor blade filled with foam material, (2) is the height (thickness) value of the sample block of the rotor blade filled with foam material, (3) is the length and width value of the sample block of the rotor blade filled with foam material, (4) is the theoretical model of the rotor blade filled with foam, (5), (6), and (7) are multiple sections of the theoretical model of the rotor blade filled with foam material divided along the span, (8), (9), (10), (11), and (12) are multiple thickness lines in section (5) of the theoretical model of the rotor blade filled with foam material divided along the span, (13), (14), (15), (16), and (17) are the foam allowance extension lines of the thickness lines of (8), (9), (10), (11), and (12), (18), (19), and (20) are the foam allowance fitting curves of each section, (21) is the fitted foam allowance surface, and (22) is the foam allowance model of the theoretical model of the rotor blade filled with foam material increased on one side. Detailed Implementation
[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] The features of various aspects of the embodiments of the present invention will now be described in detail. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can also be practiced without these specific details. The following description of the embodiments is merely intended to provide a better understanding of the invention by illustrating examples. The invention is not limited to any specific setups and methods provided below, but covers all improvements, substitutions, etc., to product structures and methods without departing from the spirit of the invention.
[0033] In the various accompanying drawings and the following description, well-known structures and techniques are not shown to avoid unnecessarily obscuring the invention. See also Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 A method for fabricating a digital model of the foam allowance for filling helicopter rotor blades.
[0034] Example 1: like Figure 8 As shown, a method for controlling the foam molding allowance of helicopter rotor blades includes the following steps: Step 1: Select polymethacrylamide (PMI) foam (1) as the filling foam material for the helicopter rotor blades, with a density of 50 kg / m3; Step 2: Based on a theoretical numerical model of the foam filling for helicopter rotor blades, determine the range of foam filling material thickness. The minimum thickness is 2mm, and the maximum thickness is 52mm. The thickness interpolation points are selected as 12mm, 22mm, 32mm, and 42mm. These six thickness values are determined as the thickness values of the foam filling material elastic compression performance test block.
[0035] Step 3: Prepare test blocks for the elastic compression performance of the foam-filled material. like Figure 1 As shown, the length and width (3) of the sample block are determined to be 42mm, and the height (2) of the sample block is 2mm, 12mm, 22mm, 32mm, 42mm and 52mm respectively. Six samples of each specification are manufactured.
[0036] Step 4: Test the compressive properties of the sample block prepared in Step 3. The compressive properties of the specimen blocks prepared in step three were tested on a pressure testing machine to obtain the range of elastic compressive deformation of the specimen blocks. The average values were 9.04%, 9.24%, 9.44%, 9.64%, 9.84%, and 10.04%, respectively.
[0037] Step 5: Create a compression performance curve for the foam filling material. Based on the compressive performance values of the foam-filled material sample block obtained from step four, the compressive performance curve of the material is fitted as follows: Figure 2 .
[0038] Step 6: Divide the theoretical numerical model of the foam filling and determine the fitting point of the foam allowance. The theoretical numerical model of the helicopter rotor blade filling foam was extracted and divided into three sections along the spanwise at equal intervals (e.g., Figure 3 The sections are (5), (6) and (7), respectively. On each section, the thickness lines of the foam filling are marked at equal intervals along the chord direction. The thickness lines of section (5) are (8), (9), (10), (11) and (12), respectively. The corresponding thickness lines of sections (6) and (7) are also marked at equal intervals.
[0039] Step 7: Fit the surface to fill the foam allowance. Based on the theoretical thickness lines at different positions of the foam filling theoretical model determined in step six, and referring to the compressibility curve of the foam filling material determined in step five, the maximum allowable size of the foam at that position is obtained. Multiplying this by a safety factor of 0.8, the applicable allowable size of the foam at that position is obtained. Based on this size, the thickness lines after adding the applicable allowable size at that position are drawn. The thickness lines of section (5) are (8), (9), (10), (11) and (12), and the corresponding applicable allowable size lines are (13), (14), (15), (16) and (17), respectively. The endpoints of these 5 lines are fitted to obtain the applicable allowable curve (18) (e.g. Figure 4 and Figure 5 (As shown). The same operation was performed on the other two profiles (6) and (7) to obtain the applicable margin curves (19) and (20) respectively.
[0040] The applicable allowance curves (18), (19), and (20) for filling foam are fitted to the applicable allowance surface (21) (as shown in the figure). Figure 6 (As shown).
[0041] Step 8: Merge the theoretical numerical model of foam filling and the numerical model of foam allowance. The foam allowance surface generated in step seven and the upper surface of the theoretical model are used as the outline to obtain the foam allowance model (22). The rotor blade foam filling theoretical model (4) and the foam allowance model (22) are combined to form the rotor blade foam filling model.
[0042] Step 9: Control and improve the quality of the adhesive interface To ensure high-quality adhesion between the filling foam and the rotor blade skin, a thin layer of SY-38C resin adhesive is applied to the surface of the filling foam. This resin adhesive should be compatible with the medium-temperature epoxy resin system of the matrix material used for the rotor blade skin.
[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.
Claims
1. A method for controlling the foam molding allowance of helicopter rotor blades, characterized in that, Includes the following steps: Step 1: Determine the type of foam material used to fill the helicopter rotor blades; Step 2: Based on the theoretical numerical model of the foam filling for helicopter rotor blades, determine the range of foam material thickness and accordingly determine the thickness value of the test block for the elastic compression performance of the foam material. Step 3: Prepare a test block for the elastic compression performance of the foam-filled material based on the thickness value of the test block determined in Step 2. Step 4: Test the elastic compression range of the foam material sample block to obtain the compression performance curve of the foam material; Step 5: Divide the theoretical numerical model of the foam filling and determine the fitting point of the foam allowance; Step 6: Fit the surface to fill the remaining foam. Step 7: Combine the theoretical numerical model of the filling foam and the numerical model of the foam margin.
2. The method for controlling the foam molding allowance of helicopter rotor blades according to claim 1, characterized in that, In step two, the method for determining the thickness value of the test block for the elastic compression performance of the foam-filled material is as follows: Measure the maximum and minimum theoretical thickness of the theoretical numerical model of the foam-filled material, insert n thickness values at equal intervals between the maximum and minimum values, and use these n values together with the maximum and minimum values as the thickness value of the test block for measuring the elastic compression performance of the foam-filled material.
3. The method for controlling the foam molding allowance of helicopter rotor blades according to claim 1, characterized in that, In step three, the sample block is a hexahedral solid shape, and the thickness value of the sample block determined in step two is used as the height of the sample block. The length and width of the sample block are equal.
4. The method for controlling the foam molding allowance of helicopter rotor blades according to claim 1, characterized in that, In step three, multiple sample blocks of the same size should be made, and the average value should be taken when testing performance.
5. The method for controlling the foam molding allowance of helicopter rotor blades according to claim 1, characterized in that, In step five, the theoretical numerical model of the helicopter rotor blade filling foam is extracted and divided into multiple cross sections along the spanwise direction at equal intervals. On each cross section, the thickness line of the filling foam is marked at equal intervals along the chordwise direction, and the endpoint of this thickness line is used as the starting point for fitting the foam allowance.
6. The method for controlling the foam molding allowance of helicopter rotor blades according to claim 1, characterized in that, In step six, based on the theoretical thickness lines at different positions of the theoretical model of the filled foam determined in step five, and referring to the compression performance curve of the filled foam material determined in step four, the maximum allowable size of the foam at that position is obtained. This is then multiplied by a safety factor to obtain the applicable allowable size of the foam at that position. The safety factor ranges from 0.6 to 0.
9. Based on this size, the thickness points at that position after adding the applicable allowable size are plotted. The thickness points on the same cross section after adding the applicable allowable size are fitted into an applicable allowable curve, and then the applicable allowable curve is fitted into a foam allowable surface.
7. The method for controlling the foam molding allowance of helicopter rotor blades according to claim 1, characterized in that, In step seven, the foam allowance surface generated in step six is used as the thickness direction shape of the theoretical model of the foam allowance to form a model with allowance for manufacturing rotor blade foam.
8. A rotor blade, characterized in that, The method for controlling the foam molding allowance of helicopter rotor blades as described in any one of claims 1-7 is adopted.