Composite paddle D-shaped beam core mold forming device and method

Abstract

The invention provides a composite paddle D-shaped beam core mold forming device and method. The device comprises a lower mold, an upper mold, a base, a left side positioning plug pin and a right side positioning plug pin. The lower die is fixed to the middle position above the base, the upper die is located above the lower die and detachably connected with the lower die, the end of the lower die is provided with a left positioning plug pin and a right positioning plug pin which are used for preventing the core die from moving in the spanwise direction when the core die is cured, and the left positioning plug pin and the right positioning plug pin are symmetrical about the vertical bisector of the device. The left positioning plug pin and the right positioning plug pin are arranged at the end of the lower die, so that the core die can be prevented from moving in the spanwise direction when the core die is cured, the core die cannot be seriously deformed due to extrusion, D-shaped beam prepreg cannot be folded and bent, and the curing forming quality is high.

Description

Technical Field

[0001] This invention belongs to the field of composite material molding technology, and particularly relates to a composite material blade D-shaped beam core mold molding device and method. Background Technology

[0002] The novel composite material blade D-beam has two pure root lugs at the root, each with a symmetrical bushing hole. These lugs connect to the hub bushing via blade pins, transferring all loads, including centrifugal force and oscillation moment, to the hub. The manufacturing of the mandrel for the composite material blade D-beam directly affects the final molding quality of the D-beam and is one of the key factors influencing its fatigue life.

[0003] Traditional composite D-beam mandrel molding processes use a foam + airbag structure. The foam is inside, and the airbag is outside. The foam provides support and facilitates prepreg application. The airbag is relatively thin; it is inflated during use to facilitate expansion and deformation, applying molding pressure to the D-beam. However, this method of mandrel manufacturing suffers from drawbacks. Due to the poor stiffness of the foam, it is prone to longitudinal slippage during curing, resulting in severe deformation under pressure. This causes wrinkles and bending of the D-beam prepreg, leading to poor curing quality. After demolding, the airbag surface is easily damaged by irreversible scratches and tears, rendering it unusable. Summary of the Invention

[0004] To address the technical problems of poor quality and non-reusability of mandrel curing, this invention provides a mandrel forming device and method for composite paddle-shaped D-beams. This device can support the forming of large-sized, heavy-duty D-beams and allows for rapid demolding and reuse.

[0005] The technical solution of this invention is: In a first aspect, a composite blade D-shaped beam core mold forming device is provided, comprising: a lower mold 1, an upper mold 2, a base 9, a left positioning pin 11, and a right positioning pin 12. The lower mold 1 is fixed in the middle position above the base 9, and the upper mold 2 is located above the lower mold 1 and is detachably connected to the lower mold 1. The end of the lower mold 1 is provided with a left positioning pin 11 and a right positioning pin 12 to prevent the core mold from moving longitudinally when it is solidified. The left positioning pin 11 and the right positioning pin 12 are symmetrical about the vertical bisector of the device.

[0006] Existing technologies for manufacturing mandrels suffer from poor foam rigidity, leading to tendency for longitudinal slippage during curing, severe deformation under pressure, wrinkling and bending of the D-beam prepreg, and poor curing quality. This invention addresses this by incorporating left and right locating pins at the ends of the lower mold. This prevents longitudinal slippage of the mandrel during curing, avoids severe deformation under pressure, prevents wrinkling and bending of the D-beam prepreg, and results in high-quality curing.

[0007] Optionally, both the left positioning pin 11 and the right positioning pin 12 are composed of a shoulder section 100 and a smooth rod section 200. The end of the shoulder section has a step difference with the inner surface cavity of the device. When laying the core mold material, a concave blind hole is formed here. This blind hole can also be used as a positioning reference for subsequent prepreg laying. The smooth rod section is used to tighten the shoulder section into place. The shoulder section and the smooth rod section are threadedly connected and can be disassembled during bag making.

[0008] Optionally, both the left positioning pin 11 and the right positioning pin 12 are fixed to the end of the lower mold 1 by clamping screws 13. The clamping screws 13 mainly serve to limit the movement and prevent the left and right positioning pins from being squeezed out when the core mold material is laid, thus achieving precise forming of the core mold shape.

[0009] Optionally, multiple leading edge blocks are provided on the upper surface of the lower mold 1 at positions corresponding to the areas where the cross-section of the core mold changes drastically. Each leading edge block is detachably connected to the lower mold 1, which greatly reduces the probability of core mold deformation during demolding and improves the core mold forming qualification rate.

[0010] Optionally, multiple leading edge blocks are arranged at equal intervals along the development direction (lower die length direction).

[0011] Optionally, the upper mold 2 and the lower mold 1 are connected by fastening bolts 10.

[0012] Optionally, all sharp edges of the outer contour of the device are rounded, and the fastening bolts are flush with the outer surface of the device.

[0013] Optionally, the device further includes: detachable lifting rings 14 on the left and right sides of the base 9 for transporting the device.

[0014] In a second aspect, a method for forming a composite blade D-shaped beam core mold is provided, for use in any of the composite blade D-shaped beam core mold forming apparatuses described in the first aspect, the method comprising: 1) Clean and apply release agent to the upper mold 2 and lower mold 1 of the composite blade D-shaped beam core mold forming device; 2) Lay core mold forming material on the upper mold 2 and the lower mold 1 respectively. At the joint of the upper mold 2 and the lower mold 1, the core mold forming material is laid in a stepped joint method. 3) Insert the left positioning pin 11 and the right positioning pin 12 into the end of the lower mold 1; 4) Flip the upper mold 2 to align it with the lower mold 1, thus completing the mold closing process; 5) Curing of the core mold material; 6) Demold the core mold material; 7) Trim and grind the edges of the core mold to achieve the final shape.

[0015] Optionally, the core molding material is a polymer memory material.

[0016] The beneficial effects of this application are as follows: 1. The core mold forming material of the present invention is a sheet material at room temperature. After heating, it can have good laying performance like composite prepreg. During molding, the shape and thickness of the core mold can be designed according to its load distribution, which has a high degree of design freedom and can adapt to the molding of various complex D-shaped beams.

[0017] 2. After the mandrel of the present invention forms the D-shaped beam, it can be reheated in the furnace to gradually soften the mandrel. A vacuum bag in the form of a loop is set at the head and end of the device. The vacuum negative pressure is used to separate the mandrel from the inner surface of the D-shaped beam. After the temperature reaches the softening point, the mandrel can be easily extracted, realizing a fast demolding method that does not damage the D-shaped beam parts.

[0018] 3. After the core mold of the present invention is demolded, its shape can be recalibrated using a molding device and then returned to the furnace for curing, enabling multiple reuses and significantly reducing manufacturing costs.

[0019] 4. The large-size D-shaped beam formed by the core mold of this invention has good surface quality and excellent product performance, which increases its fatigue test life from 1000FH to 3000FH (flight hours).

[0020] 5. To facilitate the manufacture of vacuum bags, all sharp edges and corners are rounded, bolts are countersunk, and lifting rings and pins are removable. To facilitate demolding after curing, multiple segmented blocks are installed at the R-corner closure points. Each block can be removed individually, greatly reducing the probability of part deformation during demolding and improving the part qualification rate.

[0021] 6. To prevent the core mold from shifting during curing, two 40mm diameter transverse pins are installed on the side of the device for positioning. Each pin consists of a shoulder section and a smooth rod section. The shoulder section has a step difference between its end and the inner surface cavity of the mold, primarily used to create a concave blind hole when laying the core mold material. This blind hole can also serve as a positioning reference for subsequent prepreg laying. The smooth rod section is used to tighten the shoulder section into place and is threadedly connected to it, allowing for disassembly during bag making. External small screws mainly serve a limiting function, preventing the pins from being squeezed out during core mold material laying, thus ensuring precise core mold shape. Attached Figure Description

[0022] Figure 1 This is a front view of the composite blade D-shaped beam core mold forming device of the present invention; Figure 2 Left view of the composite blade D-shaped beam core mold forming device; Figure 3 Top view of the composite blade D-shaped beam core mold forming device; Figure 4 This is a picture of the actual core mold.

[0023] Among them, 1-lower mold; 2-upper mold; 3-front edge block 1; 4-front edge block 2; 5-front edge block 3; 6-front edge block 4; 7-front edge block 5; 8-front edge block 6; 9-base; 10-fastening bolt; 11-left side positioning pin; 12-right side positioning pin; 100-shoulder section; 200-smooth rod section; 13-clamping screw; 14-lifting ring. Detailed Implementation

[0024] 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 embodiments of the present invention, not all embodiments. 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.

[0025] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0026] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited from each other.

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0028] This invention provides a core mold forming device and method capable of supporting the forming of large-size and heavy D-shaped beams, and capable of rapid demolding and reuse, for high-quality manufacturing of helicopter D-shaped beam main rotor blades.

[0029] The composite blade D-shaped beam core mold forming device mainly consists of upper and lower molds, base and other parts, and the whole presents an open-type mating mold structure.

[0030] Specifically, see Figure 1 A composite blade D-shaped beam core mold forming device includes: a lower mold 1, an upper mold 2, a base 9, a left positioning pin 11, and a right positioning pin 12. The lower mold 1 is fixed in the middle position above the base 9, and the upper mold 2 is located above the lower mold 1 and is detachably connected to the lower mold 1. The end of the lower mold 1 is provided with a left positioning pin 11 and a right positioning pin 12 to prevent the core mold from moving longitudinally when it is solidified. The left positioning pin 11 and the right positioning pin 12 are symmetrical about the vertical bisector of the device.

[0031] See Figure 2 The left positioning pin 11 and the right positioning pin 12 are both composed of a shoulder section 100 and a smooth rod section 200. The end of the shoulder section has a 5mm step difference with the inner surface cavity of the device. When laying the core mold material, a concave blind hole is formed here. This blind hole can also be used as a positioning reference for subsequent prepreg laying. The smooth rod section is used to tighten the shoulder section into place. The shoulder section and the smooth rod section are threadedly connected and can be disassembled during bag making.

[0032] See Figure 1 The left positioning pin 11 and the right positioning pin 12 are both fixed to the end of the lower mold 1 by clamping screws 13. The clamping screws 13 mainly serve to limit the movement and prevent the left and right positioning pins from being squeezed out when the core mold material is laid, so as to achieve precise forming of the core mold shape.

[0033] Furthermore, the device of the present invention may also include: a plurality of leading edge blocks disposed on the upper surface of the lower mold 1 at positions corresponding to the region where the cross-section of the core mold changes drastically, each leading edge block being detachably connected to the lower mold 1, which greatly reduces the probability of core mold deformation during demolding and improves the core mold forming qualification rate.

[0034] To improve demolding quality, multiple leading edge blocks are evenly spaced along the development direction (i.e., the length direction of the lower mold 1). See also Figure 1 Six leading edge blocks can be set, labeled 3, 4, 5, 6, 7, and 8 respectively.

[0035] The upper mold 2 and the lower mold 1 are connected by fastening bolts 10.

[0036] All sharp edges and corners of the device's outer contour are rounded, and the fastening bolts are flush with the outer surface of the device. To facilitate the manufacture of vacuum bags, all sharp edges and corners are rounded, the tightening bolts are countersunk, and the lifting rings and pins are detachable.

[0037] To facilitate demolding after curing, multiple segmented blocks are installed at the R-corner closure point. Each block can be disassembled individually, which greatly reduces the probability of part deformation during demolding and improves the part qualification rate.

[0038] The device of the present invention may further include: detachable lifting rings 14 provided on the left and right sides of the base 9 for transporting the device.

[0039] This invention provides a method for forming a core mold of a composite blade D-shaped beam, the specific forming steps of which are as follows: 1) Preparation of D-shaped beam core mold forming device, such as... Figure 1 , Figure 2 and Figure 3 As shown. After cleaning the upper and lower molds of the device with acetone and letting them dry, apply 3 to 5 coats of special release agent to the mold surface; 2) Lay the core mold forming material on the upper and lower molds respectively. Since the core mold material is relatively hard at room temperature, it can be softened by a hot air gun or curing oven before laying. At the joint of the upper and lower molds, in order to prevent local excessive thickness from affecting the joint of the device, a stepped joint should be adopted (a step width of 5mm is appropriate). 3) After the tiling is completed, place the front edge movable blocks one by one on the lower mold surface. After all the blocks are placed, insert the fastening pins to fix the blocks. 4) Insert positioning pins sequentially on both sides of the device end. The shoulder end of the positioning pin is about 5mm higher than the inner surface cavity of the mold. Insert clamping screws to prevent the positioning pins from being ejected due to excessive molding pressure during curing. 5) Flip the upper die to align with the lower die, and insert the fastening bolts to complete the die closing; 6) Insert the vacuum bag into the mold to make the tubular vacuum bag used in the molding process. Place the device into the autoclave for curing. Select a heating rate of 2-3℃, heat to 75-80℃, hold for 30 minutes, start pressurizing, pressurize to 0.5-0.6Mpa, continue heating to 170℃, hold for 30 minutes, and complete the curing. 7) When demolding, first remove the fastening pin of the front edge movable block, then remove all the blocks in sequence, loosen the tightening screws, and open the upper mold; 8) Trim and grind the core mold parts according to the part's scale lines to achieve the final shape, such as... Figure 4 As shown.

[0040] In existing technologies, the airbag needs to be peeled off from the inner surface of the D-shaped beam during curing and demolding. This peeling requires overcoming vacuum negative pressure, resulting in significant peeling force and demolding difficulties. In this invention, the core mold material is a polymer memory material that softens rapidly upon heating, thus solving the demolding difficulty problem.

[0041] In existing technologies, after demolding, the surface of the airbag is prone to irreversible scratches and tears, rendering it unusable. However, in this invention, the core mold material is a polymer memory material. The damaged core mold is placed in the molding device and re-cured, allowing it to be reshaped and solving the problem of non-reusability.

[0042] The above description merely illustrates embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Furthermore, any parts of the present invention not described in detail are conventional techniques.

Claims

1. A composite material paddle blade D-shaped beam core mold forming device, characterized in that, include: Lower mold, upper mold, base, left positioning pin, right positioning pin, The lower mold is fixed in the middle position above the base, and the upper mold is located above the lower mold and is detachably connected to the lower mold. The end of the lower mold is provided with a left positioning pin and a right positioning pin to prevent the core mold from moving longitudinally when it is solidified. The left positioning pin and the right positioning pin are symmetrical about the vertical bisector of the device.

2. The apparatus as claimed in claim 1, characterized in that, Both the left and right positioning pins consist of a shoulder section and a smooth rod section. The end of the shoulder section has a step difference with the inner surface cavity of the device. When laying the core mold material, a concave blind hole is formed here. This blind hole can also be used as a positioning reference for subsequent prepreg laying. The smooth rod section is used to tighten the shoulder section into place. The shoulder section and the smooth rod section are threaded together and can be disassembled during bag making.

3. The apparatus as described in claim 1, characterized in that, Both the left and right locating pins are fixed to the end of the lower mold by clamping screws.

4. The apparatus as claimed in claim 1, characterized in that, Multiple leading edge blocks are provided on the upper surface of the lower mold, corresponding to the area where the cross-section of the core mold changes drastically. Each leading edge block is detachably connected to the lower mold.

5. The apparatus as claimed in claim 1, characterized in that, Multiple leading edge blocks are arranged at equal intervals along the spanning direction, which is the length direction of the lower die.

6. The apparatus as claimed in claim 1, characterized in that, The upper and lower molds are connected by fastening bolts.

7. The apparatus as claimed in claim 6, characterized in that, All sharp edges of the outer contour of the device are rounded, and the fastening bolts are flush with the outer surface of the device.

8. The apparatus as claimed in claim 1, characterized in that, The device also includes detachable lifting rings on the left and right sides of the base.

9. A method for forming a composite blade D-shaped beam core mold, characterized in that, The method for the composite blade D-shaped beam core mold forming apparatus according to any one of claims 1 to 8 includes: The upper and lower molds of the composite blade D-shaped beam core mold forming device are cleaned and coated with release agent; Core mold forming material is laid on the upper mold and the lower mold respectively. At the joint of the upper mold and the lower mold, core mold forming material is laid and connected in a stepped manner. Insert the left and right locating pins into the end of the lower mold; Flip the upper mold and align it with the lower mold to complete the mold closing process; Curing of the core mold material; Demolding of the core mold material; The core mold is then trimmed and polished to achieve the final shape.

10. The method as described in claim 9, characterized in that, The core mold material is a polymer memory material.

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