Method for improving thin thickness of composite material workpiece

Abstract

The invention discloses a method for improving the thin thickness of a composite material workpiece, a forming mold of the composite material workpiece is of a structure formed by paving and curing after split mold closing, and the method comprises the steps that a set end head glue blocking scheme is used for blocking a port of the forming mold, and end head glue flowing is prevented; a set mold closing seam glue blocking scheme is used for blocking a mold closing seam of the forming mold, and glue flowing of the mold closing seam is prevented; and / or after the composite material part is paved, forming the composite material part reverse suction glue on the periphery of the composite material part by using a homologous prepreg glue blocking scheme. The method can effectively solve the problem that the thickness of a formed composite material workpiece is small.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material forming, and particularly relates to a method for improving the thickness deviation of composite material parts. Background Art

[0002] At present, when preparing parts using prepregs with good resin fluidity, the problem of the thickness of parts being too thin often occurs. Once the prepreg has passed the material identification, the resin content cannot be changed. Therefore, it is impossible to improve the thickness of parts by adjusting the raw materials. Currently, there are mainly two methods. One is to use uncured non-silicone rubber to block the glue around the parts. Since the uncured non-silicone rubber is too hard at low temperatures and cannot fit well with the parts, this method cannot block the glue well for resins with good fluidity. The other is to lay a layer of resin film on the surface of the parts after laying to compensate for the thickness. However, the resin film can only be laid on a certain layer, and these resins cannot penetrate evenly into each layer during curing. Therefore, resin accumulation will occur at the position where the resin film is placed, which will affect the local mechanical properties. This method has certain limitations. Summary of the Invention

[0003] To solve the deficiencies in the prior art, the present invention provides a method for improving the thickness deviation of composite material parts, which can effectively solve the problem of the thickness of composite material parts being too thin after forming.

[0004] To achieve the above object, the technical solution adopted by the present invention is: a method for improving the thickness deviation of composite material parts, the forming mold of the composite material parts is a structure of split mold closing and then laying and curing. The method includes: using a set end glue-blocking scheme to block the ports of the preform after laying to prevent glue flowing out from the ends; using a set mold joint glue-blocking scheme to block the mold joints of the forming mold to prevent glue flowing out from the mold joints; and / or, after the laying of the composite material parts is completed, using a homologous prepreg glue-blocking scheme around the composite material parts to form reverse glue absorption of the composite material parts.

[0005] Further, the end glue-blocking scheme includes: at the end of the preform after laying, setting uncured non-silicone rubber II along the edge of the composite material part after laying; setting sealing strip III along the outer edge of the uncured non-silicone rubber II.

[0006] Further, the width of the uncured non-silicone rubber II is 10 mm - 15 mm, the height of the sealing strip III is greater than the height of the uncured non-silicone rubber II, and the upper surface of the uncured non-silicone rubber II is higher than the upper surface of the composite material part after laying.

[0007] Further, the end glue-blocking scheme includes: at the end of the preform after laying, setting sealing strip I along the edge of the composite material part after laying; setting sealing strip II along the outer edge of the sealing strip I.

[0008] Furthermore, the height of the second sealing strip is greater than that of the first sealing strip. The upper surface of the first sealing strip is higher than the upper surface of the composite part after laying, and the joints of the second sealing strip do not coincide with those of the first sealing strip.

[0009] Furthermore, the end plugging solution includes: at the end of the preform after laying, a fourth sealing strip is arranged along the edge of the composite part after laying; an uncured non-silicone rubber three is arranged along the outer edge of the fourth sealing strip.

[0010] Furthermore, the height of the uncured non-silicone rubber three is greater than that of the fourth sealing strip, and the upper surface of the fourth sealing strip is higher than the upper surface of the composite part after laying.

[0011] Furthermore, the mold joint plugging solution includes: at the mold joint of the preform after laying, a fifth sealing strip is arranged along the mold joint; an uncured non-silicone rubber four is arranged outside the fifth sealing strip.

[0012] Furthermore, the homologous prepreg plugging solution includes: after the composite part is laid, taking the laying allowance line as a reference, a prepreg homologous to the composite part is laid to form a plugging area; a layer of uncured non-silicone rubber one is arranged outside the prepreg homologous to the composite part.

[0013] Furthermore, the number of layers of the plugging area is 10, and the width of each layer is 10 mm; the edge of the plugging area is 10 mm away from the net dimension line; a layer of uncured non-silicone rubber one with an upper surface higher than the upper surface of the part edge is arranged outside the prepreg.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention uses the set end plugging solution to plug the port of the preform after laying to prevent the end from flowing glue; uses the set mold joint plugging solution to plug the mold joint of the molding die to prevent the mold joint from flowing glue; after the composite part is laid, the homologous prepreg plugging solution is used around the composite part to form reverse suction glue for the composite part. The method of laying prepreg around can ensure that the resin uniformly penetrates into the layers, can effectively solve the problem of the too thin thickness of the composite part after molding, and does not affect the internal quality and mechanical properties of the part. Description of the Drawings

[0015] Figure 1 is a schematic structural diagram of the homologous prepreg plugging solution in the embodiment of the present invention; Figure 2 is one of the implementation schematic diagrams of the plugging solution in the test board in the embodiment of the present invention, where (a) is the schematic diagram and (b) is the physical diagram; Figure 3It is the second implementation schematic diagram of the glue plugging solution in the embodiment of the present invention during the test on the test board. Among them, (a) is the schematic diagram, and (b) is the physical diagram; Figure 4 It is the third implementation schematic diagram of the glue plugging solution in the embodiment of the present invention during the test on the test board. Among them, (a) is the schematic diagram, and (b) is the physical diagram; Figure 5 It is the physical diagram of two glue plugging solutions after demolding in the embodiment of the present invention. Among them, (a) is the physical state of the composite part after coming out of the autoclave, and (b) is the physical diagram of the surface state of the breather felt after demolding; Figure 6 It is the surface state diagram of the composite part after demolding in the embodiment of the present invention. Among them, (a) and (b) are the wrinkle state diagrams generated by the extrusion of the sealing strip on the surface of the composite part after demolding, corresponding to the glue plugging solution with the sealing strip on the inner side; (c) is the state diagram of the smooth and flat surface of the composite part after demolding, corresponding to the glue plugging solution with uncured non-silicone rubber on the inner side; Figure 7 It is the physical diagram of the flowing glue at the mold joint; Figure 8 It is the implementation schematic diagram of the glue plugging solution at the mold joint in the embodiment of the present invention. Among them, (a) is the schematic diagram, (b) is the physical Figure 1 , (c) is the physical Figure 2 ; Figure 9 It is the physical diagram of the release film fixed on the sealing strip in the embodiment of the present invention. Among them, (a) is the physical Figure 1 , (b) is the physical Figure 2 ; Figure 10 It is the physical diagram of "zero" flowing glue presented by the composite part after using the method of the present invention. Among them, (a) is the physical Figure 1 , (b) is the physical Figure 2 ; Figures 1 - 4 , Figure 8 In FIGS. Detailed implementation manners

[0016] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0017] A method for improving the thickness deviation of composite parts. The forming mold of the composite parts is a structure that is assembled from split molds and then cured after laying. The method includes: using a set end plugging scheme to block the ports of the forming mold to prevent end bleeding; using a set mold joint plugging scheme to block the mold joints of the forming mold to prevent mold joint bleeding; after the composite parts are laid, use a homologous prepreg plugging scheme around the composite parts to form reverse bleeding of the composite parts.

[0018] Scheme 1: Homologous prepreg plugging scheme.

[0019] (1) This scheme is the same as the traditional autoclave process operation method during laying. (2) After the composite parts are laid, use the homologous prepreg plugging scheme to plug the periphery of the composite parts; taking the laying allowance line as the reference, lay 10 layers of 10 mm wide homologous prepregs with high resin content to form a plugging area (the edge of the plugging area is still 10 mm away from the net size line to prevent affecting the net size area of the parts), specifically as Figure 1 shown (after the composite parts are laid, taking the laying allowance line as the reference, lay prepreg 1 homologous to the composite parts to form a plugging area; set an uncured non-silicone rubber layer 2 outside prepreg 1 homologous to the composite parts). In this way, the resin on the additional prepregs at the edge will flow towards the net size area. Compared with the traditional auxiliary material plugging scheme that can only block resin but not replenish resin, this scheme can use the homologous prepreg as the main body plugging material and improve the part thickness through reverse bleeding.

[0020] Scheme 2: Mold joint plugging scheme combined with end plugging scheme.

[0021] Since the mold itself is a structure that is assembled from split molds and then cured after laying, there are mold joints. There are mainly two bleeding channels for part bleeding, end bleeding and mold joint bleeding. Experimental verification is carried out on these two bleeding channels respectively. This scheme is the same as the traditional autoclave process operation method during laying.

[0022] Adopt the end plugging scheme to reduce end bleeding: Prepare fabric test plates respectively. On the premise of ensuring that the prepreg grade and batch, ply information, auxiliary materials, etc. are completely the same, select three different plugging methods for comparative verification (the following simulates the plugging on the formal parts through the plugging of the test plates).

[0023] (1) Fold the first sealant strip 3 in half and block it around the test plate 4. The first sealant strip 3 is close to the test plate 4 (that is, at the four peripheral edges of the preform after laying, the first sealant strip 3 is arranged along the edge of the laid composite part; the second sealant strip 5 is arranged along the outer edge of the first sealant strip 3), and the height should be higher than that of the test plate 4. A total of two layers of sealant strips for blocking glue are carried out inside and outside. The height of the outer second sealant strip 5 should be higher than that of the inner first sealant strip 3, and the disconnection positions of the two circles of sealant strips cannot coincide (that is, the height of the second sealant strip 5 is greater than that of the first sealant strip 3, the upper surface of the first sealant strip 3 is higher than the upper surface of the laid composite part, and the joint of the second sealant strip 5 does not coincide with the joint of the first sealant strip 3), as Figure 2 shown.

[0024] (2) Place the uncured non-silicone rubber two 6 with a width of (10 - 15) mm close to the part at the edge of the part (that is, at the four peripheral edges of the preform after laying, the uncured non-silicone rubber two 6 is arranged along the edge of the laid composite part), and place a circle of yellow glue higher than the uncured non-silicone rubber two 6 around the uncured non-silicone rubber two 6 (that is, the third sealant strip 7 is arranged along the outer edge of the uncured non-silicone rubber two 6), as Figure 3 shown. The height of the third sealant strip 7 is greater than that of the uncured non-silicone rubber two 6, and the upper surface of the uncured non-silicone rubber two 6 is higher than the upper surface of the laid composite part.

[0025] (3) Fold the fourth sealant strip 8 in half and block it around the test plate 4 (that is, at the four peripheral edges of the preform after laying, the fourth sealant strip 8 is arranged along the edge of the laid composite part). The fourth sealant strip 8 is close to the test plate 4, and the height should be higher than that of the test plate 4. A circle of uncured non-silicone rubber three 9 higher than the fourth sealant strip 8 is placed around the fourth sealant strip 8 (that is, the uncured non-silicone rubber three 9 is arranged along the outer edge of the fourth sealant strip 8, the height of the uncured non-silicone rubber three 9 is greater than that of the fourth sealant strip 8, and the upper surface of the fourth sealant strip 8 is higher than the upper surface of the laid composite part), as Figure 4 shown.

[0026] It can be seen from the pictures during demolding that there are no resin residue traces on the surface of the breather felt, as Figure 5 shown. All three schemes can effectively block the glue for the test plate. After removing all auxiliary materials, observing the surface of the part, it is found that in the scheme where the sealant strip is close to the part on the inner side, the sealant strip will squeeze the part inward during the curing process, resulting in apparent wrinkles on the part, as shown in Figure 6 Figure (a) in, while the apparent appearance of the part in the glue-blocking scheme with the uncured non-silicone rubber placed on the inner side is as shown in Figure 6As shown in (b), the surface of the test board is smooth and flat. Therefore, the product obtained by the scheme of placing uncured non-silicone rubber in the inner ring is better than the scheme of placing sealing rubber strips in both inner rings. Finally, the optimal scheme for plugging the end of the workpiece is to use uncured non-silicone rubber on the inner side and a sealing rubber strip on the outer side. When the requirement for the surface quality of the workpiece is not high, the scheme of placing a sealing rubber strip in the inner ring can be used as an alternative scheme.

[0027] Adopt the plugging scheme for the mold clamping joint to control the bleeding of the mold clamping joint: In the previously selected uncured non-silicone rubber plugging scheme, since the uncured non-silicone rubber has a certain hardness at low temperature and cannot perfectly fit the mold clamping joint from the outside, there is a bleeding phenomenon after curing, as Figure 7 shown. Considering that the auxiliary material for plugging the outside of the mold clamping joint 12 does not contact the workpiece and the sealing rubber strip will not squeeze the workpiece on the inner side, a softer and better-fitting sealing rubber strip five 10 is selected on the inner side and uncured non-silicone rubber four 11 is selected on the outer side for the plugging scheme, as Figure 8 shown (that is, at the mold clamping joint 12 of the forming mold, a sealing rubber strip five 10 is arranged along the mold clamping joint 12; an uncured non-silicone rubber four 11 is arranged outside the sealing rubber strip five 10).

[0028] In the present invention, the sealing rubber strip one 3, the sealing rubber strip two 5, the sealing rubber strip three 7, the sealing rubber strip four 8, and the sealing rubber strip five 10 all adopt yellow glue.

[0029] To sum up, the optimal plugging scheme selected for the end of the workpiece is the scheme of uncured non-silicone rubber (inner side) + sealing rubber strip (outer side), and the optimal plugging scheme selected for the mold clamping joint of the mold is the scheme of sealing rubber strip (inner side) + uncured non-silicone rubber (outer side). At the same time, when placing the auxiliary material in the bag making, the first layer of non-porous isolation film is fixed on the sealing rubber strip, and an exhaust channel of about 2 cm is left above the workpiece.

[0030] Since the uncured non-silicone rubber is too hard at low temperature and cannot fit the workpiece well, it is difficult to ensure the thickness of the workpiece for the prepreg with good fluidity. Through the above scheme, reverse suction of glue for the workpiece and "zero" bleeding can be achieved, and finally the thickness of each area of the workpiece can meet the requirements, as Figure 9 、 Figure 10 shown.

[0031] The traditional method of compensating the thickness by using a resin film cannot ensure that the resin uniformly penetrates into each layer, which will cause resin aggregation at the position where the resin film is laid, affecting the local mechanical properties. While the method of laying prepreg around can ensure that the resin uniformly penetrates between layers and ensure the performance of the workpiece.

[0032] The present invention uses homologous prepreg plugging to perform reverse suction of glue for the workpiece, and cooperates with a new plugging scheme to achieve "zero" bleeding, thereby ensuring that the thickness of the workpiece is at the median value; it will not cause local resin aggregation and reduce the local mechanical properties.

[0033] Verification of the effect of part thickness control.

[0034] (1) Taking a certain part as an example, the thickness of the part before and after is compared in Table 1. Among them, serial number 1 is the case of only using uncured non-silicone rubber for plugging glue, and serial number 2 is the case of plugging glue by using the above-mentioned Scheme 1 (homologous prepreg plugging glue scheme). According to the comparison of the part thickness, it can be seen that the homologous prepreg plugging glue scheme effectively improves the problem of ultra-thin part thickness.

[0035] Table 1 Comparison table of the thickness of a certain part under two schemes

[0036] (2) Taking a certain part as an example, the thickness of the part before and after is compared in Table 2 and Table 3. Among them, Table 2 is the case of only using uncured non-silicone rubber for plugging glue, and Table 3 is the case of plugging glue by using the above-mentioned Scheme 2 (mold closing seam plugging glue scheme combined with end plugging glue scheme). According to the thickness comparison, it can be seen that the mold closing seam plugging glue scheme combined with the end plugging glue scheme effectively improves the problem of ultra-thin part thickness.

[0037] Table 2 Thickness table of a certain part with only uncured non-silicone rubber for plugging glue

[0038] Table 3 Thickness table of a certain part with the mold closing seam plugging glue scheme combined with the end plugging glue scheme

[0039] In actual application, it is possible to choose to control the part thickness by only using the plugging glue method of Scheme 1 according to the actual situation, or to control the part thickness by only using the plugging glue method of Scheme 2, or to control the part thickness by using the methods of Scheme 1 and Scheme 2 at the same time.

[0040] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can still be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A method for improving the thickness deviation of composite parts, characterized in that, The forming mold of the composite part has a structure that is cured by laying and curing after split mold closing. The method includes: Using a set end plugging and sealing solution to plug the ports of the preform after laying to prevent resin flow at the ends. Using a set mold joint plugging and sealing solution to plug the mold joints of the forming mold to prevent resin flow at the mold joints. And / or, After the composite part is laid, use a homologous prepreg plugging and sealing solution around the composite part to form reverse resin absorption of the composite part.

2. The method for improving the thickness deviation of a composite part according to claim 1, characterized in that, The end plugging and sealing solution includes: At the ends of the preform after laying, set uncured non-silicone rubber two (6) along the edge of the laid composite part. Set sealing strip three (7) along the outer edge of the uncured non-silicone rubber two (6).

3. The method for improving the thickness deviation of the composite material part according to claim 2, wherein The width of the uncured non-silicone rubber two (6) is 10 mm to 15 mm. The height of the sealing strip three (7) is greater than the height of the uncured non-silicone rubber two (6). The upper surface of the uncured non-silicone rubber two (6) is higher than the upper surface of the laid composite part.

4. The method for improving the too-thin thickness of a composite part according to claim 1, wherein The end plugging and sealing solution includes: At the ends of the preform after laying, set sealing strip one (3) along the edge of the laid composite part. Set sealing strip two (5) along the outer edge of the sealing strip one (3).

5. The method for improving the thickness deviation of composite parts according to claim 4, wherein, The height of the sealing strip two (5) is greater than the height of the sealing strip one (3). The upper surface of the sealing strip one (3) is higher than the upper surface of the laid composite part, and the joints of the sealing strip two (5) do not coincide with the joints of the sealing strip one (3).

6. The method for improving the thickness deviation of the composite part according to claim 1, wherein The end plugging and sealing solution includes: At the ends of the preform after laying, set sealing strip four (8) along the edge of the laid composite part. Set uncured non-silicone rubber three (9) along the outer edge of the sealing strip four (8).

7. The method for improving the thickness deviation of the composite material part according to claim 6, characterized in that, The height of the uncured non-silicone rubber three (9) is greater than the height of the sealing strip four (8). The upper surface of the sealing strip four (8) is higher than the upper surface of the laid composite part.

8. The method for improving the too-thin thickness of the composite part according to claim 1, characterized in that, The mold joint plugging and sealing solution includes: At the mold joints of the preform after laying, set sealing strip five (10) along the mold joints. Set uncured non-silicone rubber four (11) outside the sealing strip five (10).

9. The method for improving the thickness deviation of composite parts according to claim 1, characterized in that, The homologous prepreg plugging and sealing solution includes: After the composite part is laid, taking the laying allowance line as the reference, lay prepreg (1) homologous to the composite part to form a plugging area. Set a layer of uncured non-silicone rubber one (2) outside the prepreg (1) homologous to the composite part.

10. The method for improving the too-thin thickness of the composite part according to claim 9, characterized in that, The laying quantity of the plugging area is 10 layers, and the width of each layer is 10 mm. The edge of the plugging area is 10 mm away from the net size line. A layer of uncured non-silicone rubber one (2) with an upper surface higher than the upper surface of the part edge is set outside the prepreg.

Images