CN104723571B - The method of sewing of a kind of carbon fiber cell type prefabricated component and shaper - Google Patents
The method of sewing of a kind of carbon fiber cell type prefabricated component and shaper Download PDFInfo
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Abstract
The present invention discloses method of sewing and the shaper of a kind of carbon fiber cell type prefabricated component.This method of sewing comprises the following steps: first, according to the design size of cell type prefabricated component and lamination angle cutting carbon cloth laying；Secondly, in the way of completely penetrating through, the bottom of cell type prefabricated component inner chamber is sewed up；The bottom that cell type preform side wall is corresponding is sewed up again in partial penetration mode；3rd, utilize molding core that the carbon cloth of two-dimension laminate structure is rolled into the case type structures of solid；4th, it is sprayed at equably on cell type prefabricated component with distilled water after making it drenched, heats pre-setting with shaper；5th, sew up cell type preform side wall completely penetrating through mode；6th, again it is sprayed at equably on cell type prefabricated component with distilled water and makes it drench, then with shaper heat-shaping and get final product.This shaper includes shape external mold and molding core, and molding core is the box body that three components connect, and sizing external mold is the box body of six template body assemblings.
Description
Technical Field
The invention relates to a preparation technology of a composite material prefabricated part, in particular to a sewing method and a shaping mold of a carbon fiber box type prefabricated part.
Background
The traditional two-dimensional laminated composite material has good in-plane mechanical property, but the fiber reinforcement is not arranged between the layers, and the matrix resin is used for bonding and transmitting load, so that the performance in the direction perpendicular to the laying direction and between the laying layers is relatively weak. When subjected to external loads, the laminated composite tends to first cause interlaminar failure, and the lower interlaminar strength of the composite also results in a composite having poor damage resistance. To ameliorate these disadvantages of laminated composites, a number of techniques have emerged to increase the interlaminar toughness of composites. The sewing technology can obviously improve the interlayer strength and the impact resistance of the composite material, the sewn composite material has strong structural integrity, and the sewn composite material is applied to some simple components such as wings, automobile baffles and the like at present.
Box-type composite materials are widely used in structural members for aerospace, for example: computer machine case, add muscle box section, apron etc.. Because box type prefab is yielding at the sewing in-process, and sews up the back dimensional stability relatively poor, is difficult to guarantee the higher dimensional accuracy of box type prefab, and the actual application has the bottleneck. In the scope of the applicant's search, no literature reports on the sewing technology related to the carbon fiber box-type structure preform are found.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to solve the technical problem of providing a sewing method and a shaping mold for a carbon fiber box-shaped prefabricated part, wherein the sewing method and the shaping mold can ensure that the carbon fiber box-shaped prefabricated part has higher dimensional precision and higher dimensional stability, and the carbon fiber box-shaped prefabricated part sewn by the method and the shaping mold has higher fiber volume content and excellent mechanical property of a composite material.
The technical scheme for solving the technical problem of the method is to design a sewing method of a carbon fiber box type prefabricated part, which comprises the following steps: firstly, cutting carbon fiber cloth according to the design size and the lamination angle of a box-type prefabricated part and laying; secondly, sewing the bottom of the inner cavity of the box-shaped prefabricated part in a completely penetrating manner; sewing the bottom corresponding to the side wall of the box-shaped prefabricated part in a partially penetrating mode; thirdly, wrapping the carbon fiber cloth with the two-dimensional laminated structure into a three-dimensional box-shaped structure by using a forming core mold; fourthly, uniformly spraying distilled water on the box-shaped prefabricated member to thoroughly wet the box-shaped prefabricated member, and heating and pre-shaping the box-shaped prefabricated member by using a shaping mold; fifth, the sidewall of the box-type preform is sewn in a completely penetrating manner; sixthly, uniformly spraying distilled water on the box-shaped prefabricated member again to enable the box-shaped prefabricated member to be thoroughly wetted, and then heating and shaping the box-shaped prefabricated member by using a shaping mold to obtain the finished product;
the partially penetrating sewing method is characterized in that the number of layers required by the process is uncovered from the laminated carbon fiber cloth at the bottom of the inner cavity of the sewn box-type prefabricated part, and a circle of the remaining carbon fiber cloth is sewn at a position with the horizontal distance of the outer contour line of the sewn area as a line pitch, namely, one-time partially penetrating sewing is completed; the number of partial penetrating and sewing is that the thickness of the side wall of the box-shaped prefabricated member is divided by the line spacing and then is reduced by 1, and if the obtained number of times is not an integer, the number of times is rounded;
the method for wrapping the box-type prefabricated member comprises the steps of cutting a layer or a group of carbon fiber cloth in a three-dimensional mode, removing redundant carbon fiber cloth, lifting and folding the reserved carbon fiber cloth, attaching the reserved carbon fiber cloth to the molded surface of a forming core mold or wrapping the carbon fiber cloth on the forming core mold without folds, clamping the erected carbon fiber cloth on the side wall of the forming core mold by a clamp, pre-sewing a butt joint by a pre-sewing line, repeatedly cutting and wrapping until all the carbon fiber cloth is wrapped on the forming core mold, and achieving the side wall thickness required by the prefabricated member;
the heating temperature for presetting is 80-150 ℃, and the heating time is 0.5-2 hours;
the heating temperature for shaping is 80-150 ℃, and the heating time is 0.8-3 hours;
the specific number of layers required by the uncovering process needs to consider a wrapping method, so that the thickness of the uncovered carbon fiber cloth wrapped on the side wall after related wrapping operation is just one line spacing;
the pre-sewing operation method is that a pre-sewing thread with the fineness lower than the carbon fiber cloth warp and weft is used for sewing 4 to 20 needles of the butt joint so as to fix the butt joint together; the material of the pre-sewing line is carbon fiber or a material which can be decomposed in the final composite process of the box-type prefabricated member.
The invention solves the technical scheme that a shaping mould of a box-shaped prefabricated member is designed, the shaping mould is suitable for the sewing method of the carbon fiber box-shaped prefabricated member, and the shaping mould is characterized by comprising a shaping outer mould and a shaping core mould, wherein the shaping core mould is a box-shaped body and is formed by sequentially connecting and fastening three detachable components, the connecting direction of the three components is the length direction of the box-shaped prefabricated member, and the outer wall profile of the shaping core mould is the profile of the inner cavity of the box-shaped prefabricated member; the three components of the forming mandrel are: a plate-shaped body member, two box-shaped body members, the plate-shaped body member is positioned in the middle, and the two box-shaped body members are positioned at two sides of the middle plate-shaped body member and connected;
the shaping outer die is a box-shaped body formed by connecting and assembling six plate-shaped bodies, namely a front template, a rear template, a left template, a right template, a top template and a bottom template, and the molded surface of the inner wall of the box-shaped body is the molded surface of the outer wall of the box-shaped prefabricated member; the shaping external mold is matched with the shaping core mold, so that the shaping core mold coated with the carbon fiber cloth can be arranged in the shaping external mold; the molded surface of the bottom plate molded body of the shaping outer mold corresponds to the molded surface of the bottom of the box-shaped prefabricated part, and the molded surface of the bottom plate molded body is provided with through holes for discharging water vapor in the bottom of the prefabricated part in the pre-shaping and shaping processes; the profile of design external mold front formword, back template, left template and right template plate type body corresponds the profile of box type prefab lateral wall, and the plate type body of top template corresponds the top of box type prefab lateral wall, for making the box type prefab in the steam in the box type prefab lateral wall of preforming and design in-process discharge, there are two kinds of exhaust structural design: one structure is that the width of the top template is smaller than that of the inner cavity of the box-type prefabricated member, so that the top of the long side wall of the box-type prefabricated member is exposed for exhausting; the other structure is that the molded surfaces of the front template, the rear template, the left template and the right template are provided with through holes for exhausting.
Compared with the prior art, the sewing method of the box-type prefabricated member and the die for shaping the box-type prefabricated member can realize the conversion of the carbon fiber cloth from a two-dimensional laminated structure to a three-dimensional box-type structure, and the prefabricated member has better integrity; sizing agent contained in the carbon fiber is used as sizing agent, and the sizing effect can be achieved only by spraying distilled water on the prefabricated member; through two shaping processes of pre-shaping and shaping, the dimensional accuracy and stability of the box-shaped prefabricated member in and after the sewing process are fully ensured; the core mould adopts a mode of connecting and fastening three components and a box-shaped structure, so that the core mould is easy to disassemble and assemble and is convenient for clamping and fixing the prefabricated part. The box-shaped preform sewn by the method of the invention has a high fiber volume content (more than 50%).
Drawings
FIG. 1 is a schematic structural dimension diagram of a box-shaped preform according to an embodiment of the sewing method of the present invention.
Fig. 2 (including fig. 2(a) to 2(j)) is a process flow diagram of an embodiment of the sewing method of the present invention. Wherein,
fig. 2(a) is a schematic view of a process of laying a carbon fiber cloth in one embodiment of the sewing method of the present invention.
FIG. 2(b) is a schematic view showing a bottom process for sewing the inner cavity of the box preform in a completely penetrated manner in one embodiment of the sewing method of the present invention.
Fig. 2(c) is a schematic view of the bottom process corresponding to sewing the sidewall of the box preform in a partially penetrated manner in one embodiment of the sewing method according to the present invention.
FIG. 2(d) is a schematic view of a process for wrapping the side wall of the box-shaped preform according to an embodiment of the sewing method of the present invention.
FIG. 2(e) is a schematic view of a process for pre-forming a box-shaped preform according to an embodiment of the sewing method of the present invention.
FIG. 2(f) is a schematic view showing a process of sewing the bottom of the sidewall of the box preform in a completely penetrating manner in one embodiment of the sewing method of the present invention.
FIG. 2(g) is a schematic view showing a process of sewing the middle part of the side wall of the box preform in a completely penetrating manner in one embodiment of the sewing method of the present invention.
Fig. 2(h) is a schematic view of a process of sewing four corners of the side wall of the box preform in a completely penetrating manner in one embodiment of the sewing method of the present invention.
FIG. 2(i) is a schematic view showing a process of shaping a box-shaped preform according to an embodiment of the sewing method of the present invention.
FIG. 2(j) is a schematic view of a final product of a box-shaped preform according to an embodiment of the sewing method of the present invention.
FIG. 3 is a schematic view of the bottom position of the inner cavity of the box-shaped preform according to one embodiment of the sewing method of the present invention.
FIG. 4 is a schematic view showing the effect of sewing the bottom of the inner cavity of the preform in a completely penetrated manner in one embodiment of the sewing method of the present invention.
FIG. 5 is a schematic view of a method of sewing a bottom sidewall region in a partially penetrated manner according to an embodiment of the sewing method of the present invention.
FIG. 6 is a schematic view showing the bottom effect of the box preform before and after sewing the bottom sidewall region in a partially penetrated manner according to an embodiment of the sewing method of the present invention.
FIG. 6(a) is a schematic view showing the effect of sewing the bottom sidewall region in a partially penetrated manner before sewing in one embodiment of the sewing method of the present invention.
FIG. 6(b) is a schematic view showing the effect of sewing the bottom sidewall region in a partially penetrated manner in one embodiment of the sewing method of the present invention.
FIG. 7 is a schematic view showing a position where a forming core mold is placed in a step of wrapping a box-shaped preform according to an embodiment of the sewing method of the present invention.
Fig. 8 is a schematic view showing a core mold structure in an embodiment of the sewing method of the present invention.
FIG. 9 is a schematic view of a wrapping method according to an embodiment of the sewing method of the present invention.
FIG. 9(a) is a schematic view of a first three-dimensional cutting method for a side wall of a package according to an embodiment of the sewing method of the present invention.
Fig. 9(b) is a schematic diagram of a wrapping effect corresponding to the cutting manner of fig. 9(a) in an embodiment of the sewing method of the present invention.
FIG. 9(c) is a schematic view of a second three-dimensional cutting method for wrapping sidewalls in an embodiment of the sewing method of the present invention.
Fig. 9(d) is a schematic diagram of a wrapping effect corresponding to the cutting manner of fig. 9(c) in an embodiment of the sewing method of the present invention.
FIG. 9(e) is a schematic view of a third three-dimensional cutting method for wrapping sidewalls in an embodiment of the sewing method of the present invention.
Fig. 9(f) is a schematic diagram of a wrapping effect corresponding to the cutting manner shown in fig. 9(e) in an embodiment of the sewing method of the present invention.
FIG. 10 is a schematic view of a pre-sewn seam in the step of wrapping the box-shaped preform according to an embodiment of the sewing method of the present invention.
Fig. 11 is a schematic structural view of a shaping mold according to an embodiment of the shaping mold of the present invention.
Fig. 12 is a schematic diagram of the effect of the shaping mold after closing in one embodiment of the shaping mold according to the present invention.
Fig. 13 is a schematic view illustrating that the middle plate body is taken out during the mold opening process of the setting mold according to one embodiment of the setting mold.
FIG. 14 is a schematic view of three sewing regions corresponding to three steps of sewing the sidewall in an embodiment of the sewing method of the present invention.
Detailed Description
The invention will be further described with reference to the following examples and figures:
the sewing method (abbreviated as method or sewing method, see fig. 1-14) of the box-shaped prefabricated member designed by the invention comprises the following steps: firstly, cutting carbon fiber cloth according to the design size and the lamination angle of a box-type prefabricated part and laying; secondly, sewing the bottom 201 of the inner cavity of the box-type prefabricated member in a completely penetrating manner; sewing the bottom 202 corresponding to the side wall of the box-shaped prefabricated member in a partially penetrating manner; thirdly, wrapping the carbon fiber cloth with the two-dimensional laminated structure into a three-dimensional box-shaped structure by using a forming core mold 320; fourthly, uniformly spraying distilled water on the box-shaped prefabricated member to thoroughly wet the box-shaped prefabricated member, and heating and pre-shaping the box-shaped prefabricated member by using a shaping mold; fifth, the sidewall of the box-type preform is sewn in a completely penetrating manner; sixthly, uniformly spraying distilled water on the box-shaped prefabricated member again to enable the box-shaped prefabricated member to be thoroughly wetted, and then heating and shaping the box-shaped prefabricated member by using a shaping mold to obtain the finished product;
the specific sewing technology can adopt methods such as lock sewing or chain sewing, and the like, which are the prior art.
The stitching thread used for the stitching is required to be high-temperature-resistant high-performance fiber, and carbon fiber or graphite fiber can be used, depending on the application of the prefabricated member. The thicker the fineness of the suture, the better the interlaminar performance of the prefabricated member, but the greater the damage to the intrafacial performance, and the specific fineness of the suture is determined according to the design requirements.
The invention relates to an anti-edge-drop technology of carbon fiber cloth and a technology for cutting the carbon fiber cloth, belonging to the prior art.
The carbon fiber cloth raw material contains the water-soluble sizing agent or the emulsion sizing agent, and the water-soluble sizing agent or the emulsion sizing agent can play a role in shaping after being combined with distilled water in the pre-shaping and shaping procedures of the prefabricated member (which will be described in detail later), so that other shaping agents do not need to be purchased and used. Currently, most of the carbon fiber fabrics on the market contain sizing agents when leaving the factory, wherein the emulsion sizing agent is most widely applied (see horse rigid front, et al. development and research progress of carbon fiber sizing agents [ J ], modern textile technology, 2012(5): 61-64). In particular, the invention is not suitable for carbon fiber cloth after the sizing agent is removed after the carbon fiber cloth leaves a factory.
In the step of the sewing method for the box-type prefabricated member, the bottom 201 of the inner cavity of the prefabricated member is sewn firstly, so that each layer of carbon fiber cloth is sewn together firmly, and tension can be applied by taking the bottom of the prefabricated member as a reference in the later process of wrapping the side wall, so that the carbon fiber cloth of the side wall can be attached to the molded surface of the core mold 320 or the carbon fiber cloth wrapped on the core mold without folds.
The fabric cutting layer number is required to meet the fiber volume content required by the box type prefabricated member, the specific calculation method is the prior art, and the fabric cutting layer number can be determined by combining parameters such as the surface density of carbon fiber cloth raw materials, the density of carbon fibers and the like.
The size of the cut cloth is larger than the size of the box-type prefabricated member after two-dimensional expansion by taking the bottom as a reference, so that the cut carbon fiber cloth can reach the size required by the prefabricated member after the subsequent wrapping process. Taking the rectangular box preform as an example, the fabric cutting size includes the length and width of the carbon fiber fabric, and the length is greater than the sum of the length of the bottom of the preform and the height of the two side walls. The width is greater than the sum of the width of the preform and the height of the two sidewalls. The size of the cloth cutting is larger than the sum of the bottom size and the two side walls, so that the problem that the carbon fiber cloth on the side wall of the final prefabricated member cannot reach the expected height due to later operation errors and shrinkage of the carbon fiber cloth is solved, and the size requirement of three-dimensional cutting is met by combining the size of the cut cloth with a method for wrapping the prefabricated member in a three-dimensional mode.
The partially penetrating sewing method is that the number of layers 203 required by the process is uncovered from the laminated carbon fiber cloth sewn at the bottom 201 of the inner cavity of the box-shaped prefabricated member, and a circle of the rest carbon fiber cloth 204 is sewn at the position with the horizontal distance of the outer contour line 205 of the sewn area as a line pitch, namely, one-time partially penetrating sewing is completed; the number of partial penetration stitches is the thickness of the side wall of the box preform divided by the row pitch, minus 1, rounded if the number is not an integer.
The specific number of layers 203 required by the uncovering process needs to consider a wrapping method, so that the thickness of the uncovered carbon fiber cloth wrapped on the side wall after relevant wrapping operation is just one line spacing; when the thickness of the bottom of the box-shaped prefabricated member to be sewn is equal to that of the side wall, the operation of adding or reducing layers is not needed to be carried out on the cloth on the side wall in the wrapping process, the number of the uncovered layers is the number of the side wall, and therefore the number of the cloth layers uncovered each time is the number of the cloth layers with one row spacing; if the thickness of the bottom of the box-type prefabricated member is larger than that of the side wall, a part of cloth needs to be cut off in the wrapping process, and the number of layers of the cloth which is uncovered each time is the sum of the number of layers of the thickness of one row spacing and the number of layers which are pre-cut off; if the thickness of the bottom of the box-type prefabricated member is smaller than that of the side wall, a certain number of layers of cloth needs to be additionally added in the wrapping process, and the number of layers of cloth uncovered each time is the number of layers of the thickness of one row spacing minus the number of layers of the added cloth. This ensures that each row pitch of the preform bottom sidewall region 202 is the same as the cloth thickness of its corresponding sidewall.
The sewing method of the box-type prefabricated member sews the bottom side wall area 202 of the prefabricated member in a partial penetrating way, so that the root of the cloth of the side wall to be wrapped is fixed at a corresponding position along with the shape, the cloth can not generate large displacement in the wrapping operation, and the dimensional precision of the bottom side wall area 202 is ensured.
The method for wrapping the box-type prefabricated member is that a core mould 320 is placed right above an inner cavity bottom 201 sewn in a completely penetrating mode, the edge contour line 205 of the bottom 201 of an inner cavity and the bottom edge 301 of the core mould 320 are cut in a three-dimensional mode, one layer or a group of carbon fiber cloth is cut, the redundant carbon fiber cloth is removed, the reserved carbon fiber cloth is lifted and folded, the carbon fiber cloth is attached to the molded surface of the core mould 320 or wrapped on the carbon fiber cloth on a forming core mould without folds, the erected carbon fiber cloth is clamped on the side wall of the core mould 320 by a clamp, the butt joint is pre-sewn by a pre-sewing thread 307, cutting and wrapping are repeated until all the carbon fiber cloth is wrapped on the forming core mould 320, and the side wall thickness required by the prefabricated member is achieved;
the principle of the three-dimensional cutting of the carbon fiber cloth is that the cut carbon fiber cloth is erected and folded, the core mold 320 or the carbon fiber cloth wrapped on the mold can be wrapped completely, and the interfaces after one layer or a group (several layers) of adjacent carbon cloth is wrapped on the mold are distributed at the positions with lower performance requirements according to the performance requirements of the final composite material of the box-type prefabricated member.
The number of layers of cutting and wrapping operation of the wrapping box type prefabricated part is determined according to the thickness of the fabric, if the thickness of the carbon fiber cloth is thin, only one layer of carbon cloth is wrapped at each time, the efficiency is too low, and meanwhile, the probability of wrinkles of the carbon fiber cloth on the side wall is improved. If the number of layers per operation is large, the dimensional accuracy of the preform is affected if the cloth to be operated is thick. The thickness of one layer or group of carbon fibers per operation is preferably 0.4mm to 1.2 mm.
The pre-sewing operation method comprises the steps that 4-20 needles of butt joints are sewn by using sewing threads, so that the butt joints are fixed together, the number of the pre-sewing needles is as small as possible on the premise of achieving sewing and fixing, and the pre-sewing threads are prevented from being clamped between carbon fiber cloth to influence the size precision of the prefabricated part; the material of the pre-sewing thread is carbon fiber or a material (terylene or nylon and the like) which can be decomposed in the final composite process of the box-type prefabricated part, so that the existence of foreign matters in the final composite material product can be reduced, and the influence on the performance of the final composite material product is prevented; the fineness of the pre-sewing yarn 307 is lower than the fineness of the warp and weft of the carbon fiber cloth, if the fineness of the pre-sewing yarn 307 is too thick, the thickness and the size precision of the prefabricated part are influenced, and if the fineness of the pre-sewing yarn 307 is too thin, the fixing effect cannot be realized.
The distance between the needle hole sewed by the pre-sewing thread and the selvage is more than 10mm so as to prevent the fibers at the fracture from being loosened.
The pre-sewing operation has moderate tension, too small force cannot play a role in fixing, and too large force can cause local fibers to be deformed by too large tension.
The method for three-dimensionally cutting the carbon fiber cloth in the wrapped box type prefabricated member belongs to the prior art.
The specific method for presetting comprises the following steps: firstly, trimming redundant burrs of the box-shaped prefabricated member to enable cloth on the side wall to be flush with the top end of the side wall of the core mold 320, uniformly spraying distilled water on the box-shaped prefabricated member, and lightly pressing the side wall of the prefabricated member to enable the fabric to be thoroughly wetted; then, the outer mold 400 is closed, and the mold (including the box-shaped preform) is heated and dried; after the heating is finished and the mold is naturally cooled, the mold is opened, the external mold 400 is disassembled, then the middle plate-shaped body 322 of the core mold (core mold) is taken out, and finally the two side members 321 and 323 of the core mold are taken out.
The specific method of the sizing is that the left and right side components 321 and 323 of the sizing core mould 320 are firstly placed at the corresponding positions of the left and right sides in the cavity of the box-shaped prefabricated part, and then the middle plate-shaped body 322 is plugged in. Uniformly spraying distilled water on the prefabricated part again, slightly pressing the side wall of the prefabricated part to thoroughly wet the prefabricated part, and closing the outer mold 400; heating and drying the mold (containing box type prefabricated part); and finally, opening the mold, wherein the method is the same as the method for pre-shaping the mold, and trimming the rough edges of the side wall of the prefabricated part to obtain the fabric, namely the required prefabricated part.
The spraying amount of the distilled water in the presetting and the setting is according to the volume of the box-shaped prefabricated member. If the spraying amount is too low, the prefabricated part cannot be soaked in the thickness direction by the distilled water, so that the layers cannot be bonded together; if the spraying amount is too high, a large amount of moisture overflows after the prefabricated part is subjected to die assembly, and the working environment is polluted. The box-type preform sewn by the method described in this patent generally has a fiber volume content higher than 50% and the amount of distilled water sprayed onto the preform should be higher than half the volume of the preform voids. The specific spraying amount should be more than 0.2g/cm3。
The heating temperature for presetting and shaping is proper, if the heating temperature is too low, the steam evaporation efficiency is low, meanwhile, the sizing agent is not easy to dissolve, and if the temperature is too high, the sizing agent in the carbon fiber cloth can be decomposed. The specific temperature can be controlled between 80 ℃ and 150 ℃.
The heating time of the presetting is controlled to evaporate more than 50% of water in the prefabricated member, and the heating time is controlled to be 0.5 to 2 hours according to the heating temperature. If the heating time is too short, most of the moisture in the box-type prefabricated part can not be evaporated and can not play a role in shaping, but the heating time is preferably not too long, if the moisture in the box-type prefabricated part is completely evaporated, the box-type prefabricated part is too hard, the subsequent side wall sewing process is difficult to penetrate through the side wall, in-plane fibers of the side wall are easy to break when contacting sewing needles, and the in-plane performance of the final composite side wall is reduced.
The heating time of the shaping is controlled to enable the prefabricated member to evaporate more than 70% of moisture, because the shape of the prefabricated member is generally not changed by normal external force of packaging and transportation after 70% of moisture is evaporated, and the heating time is controlled to be 0.8 to 3 hours according to the heating temperature.
The method for detecting the evaporation capacity of the water in the prefabricated member in the process of performing pre-setting or setting on the prefabricated member is the prior art and can be obtained by repeated tests of methods such as weighing and the like.
In the pre-shaping and shaping process of the prefabricated member, only distilled water is needed to be added to play a role of a shaping agent, and the content of the sizing agent containing a water-soluble or water emulsion component in the carbon fiber cloth is about 1.2 percent (see the application progress of high-performance carbon fiber sizing agents such as Yehaijun and the like J, the light textile industry and technology 2012,41(3): 62-65). Under the action of heating and pressurizing, water soluble or water emulsion components are dissolved into water from the surface of the fiber to become solution or emulsion again, and the sizing agent has high viscosity and can be just used as a sizing agent of the prefabricated member, so that carbon cloth layers can be bonded together in a mold, and the prefabricated member has certain dimensional stability after being dried, so that various operations can not influence the macroscopic box shape of the prefabricated member in the later process of sewing the side wall.
When the prefabricated member is used for carbon/carbon and ceramic matrix composite materials, the components of the sizing agent can be completely decomposed in the later-stage composite forming process of the prefabricated member in a high-temperature environment, and the final performance of a final composite material product cannot be influenced; if the box-type prefabricated member is used for resin-based composite materials, the sewed prefabricated member can be put into a relevant solvent for dissolving, and the technology for dissolving the sizing agent is the prior art.
According to the sewing method of the box-type prefabricated member, the prefabricated member is soaked in a distilled water spraying mode, the method is simple and convenient, each layer of carbon fiber cloth of the prefabricated member can obtain moisture, and even if the spraying amount is not uniform enough, the distribution density of the moisture in the prefabricated member can be adjusted again after the next mould pressurizing procedure.
In the box-shaped prefabricated part pre-shaping and shaping process, part of sprayed distilled water may overflow from a mould due to the action of mould-closing pressure in the mould-closing process, and sizing agent components in carbon fibers are not easy to dissolve in water at normal temperature, so that the mould-closing process is operated at normal temperature, and even if part of water is lost, the loss of a large amount of sizing agent is not caused, and the shaping effect is not influenced.
The seaming of the side walls of the box-shaped preform in a completely penetrating manner is divided into three steps: firstly, sewing the bottom end 501 of the side wall of the prefabricated part after opening the mould; then sewing the middle part 502 of the side wall of the prefabricated part and finally sewing the four corners 503 of the prefabricated part, wherein the sewing modes of the process are all in a completely penetrating mode and follow the sewing directions from bottom to top and from the middle to the two sides, so that the wrinkles caused by the concentrated operation errors of the three-dimensional package are prevented.
The number of rows at the bottom of the preform sidewall is the bottom thickness divided by the row spacing, rounded to an integer number of rows if the result is not an integer.
The invention has designed the sizing die of the prefabricated member of carbon fiber box type at the same time, it is made up of shaping mandrel 320 and shaping external mold 400, said shaping mandrel 320 can wrap up the carbon fiber cloth of the two-dimentional laminated structure into the three-dimensional box type structure, said shaping mandrel 320 itself is a box-shaped body (contain a check in the middle), connect and fasten sequentially by three removable components, its connection direction is the length direction of the prefabricated member of box type, the outer wall profile of said mandrel 320 is the profile of the inner chamber of prefabricated member of box type;
the outer mold 400 is composed of a front mold plate 401, a rear mold plate 402, a left mold plate 403, a right mold plate 404, a bottom mold plate (bottom plate for short) 405 and a top mold plate (top plate for short) 406. The six plate-type bodies are connected and assembled to form a box-type body, and the molded surface of the inner wall of the box-type body is the molded surface of the outer wall of the box-type prefabricated member; the outer mold 400 is matched with the core mold 320, so that the core mold 320 wrapped with the carbon fiber cloth can be arranged in the outer mold 400;
the three components of the forming mandrel 320 are: one plate-shaped body member 322, two cartridge-shaped body members 321 and 323, the plate-shaped body member 322 being positioned in the middle, and the two cartridge-shaped body members 321 and 323 being connected at both sides of the middle plate-shaped body member 322. The three components are divided so as to be conveniently and smoothly placed into the box-type prefabricated member in the later shaping process of the prefabricated member. If the core mold 320 is an integral type, it is difficult to fit the core mold into the preform cavity due to elastic shrinkage of the preform fabric during the mold closing process. If the mold is divided into three components, the left side component 321 and the right side component 323 are firstly plugged into the prefabricated component during mold closing, and then the middle plate-shaped body 322 is plugged, so that the pressure of the fabric on the mold is converted into the friction force among the three plate-shaped bodies, and the plugging of the mold is easy to realize.
The intermediate plate member 322 may have a taper such that it has a smaller thickness at its lower end and a larger thickness at its upper end, and is inserted between the left and right side members 321 and 323 of the core mold 320 when the mold is closed.
The three components of the core mold 320 can be detachably combined, the connection fastening technology is the prior art, and the three components are connected together in the process of wrapping the box-shaped prefabricated member. The present embodiment is fastened together by two sets of bolts 324 through the side walls of the left side member 321, the middle plate-shaped body 322 and the right side member 323 by nuts 325.
The box-shaped cavity of the core mold 320 provides an operating space and a sidewall structure for assembling and disassembling the three-component mold.
The side wall of the core mold 320 is convenient for clamping by a clamp in the process that the prefabricated member is wrapped by the carbon fiber cloth at the later stage.
The thickness of the sidewall of the core mold 320 is smaller than the difference between the distance of the opened clip and the thickness of the wall of the box-type preform, so that the carbon fiber cloth of the sidewall of the preform can be clipped on the sidewall of the core mold. The thinner the wall of the core mold, the more convenient it is to clamp, but the too thin wall may cause deformation of the core mold during processing, depending on the size of the box preform and the processability of the material.
The thickness of the plate-shaped body 322 in the core mold 320 is determined according to the size of the preform and the workability of the mold material, and the thinner the plate-shaped body 322 is, the easier it is to assemble and disassemble, but the thinner the plate-shaped body is, the more easily the plate-shaped body is deformed.
The material of the shaping mold is high-temperature resistant (considering the highest temperature in the process of pre-shaping or shaping) on one hand, so that the large deformation of the mold in the process of post-pre-shaping or shaping and heating of the prefabricated part is prevented; on the other hand, oxidation resistance is required to prevent the preform from being contaminated by oxidation products of the mold during heating. The prefabricated part mould can be made of hard aluminum, stainless steel, bakelite and the like.
The molding surface of the shaping mold in contact with the prefabricated member can be pasted with a high-temperature-resistant demolding adhesive tape 326, the polytetrafluoroethylene demolding adhesive tape is most commonly applied at present, the carbon fiber prefabricated member can be prevented from being polluted by the substances on the surface of the mold, and meanwhile, the subsequent demolding procedure is easy to carry out.
Two positioning pin holes 327 can be reserved in the middle plate-shaped body 322 of the core mold, and two positioning pin holes 408 are also reserved at corresponding positions of the top mold plate 406 of the outer mold 400, so that the connection positioning pins between the outer mold 400 and the middle plate-shaped body can be realized.
The top end of the plate 322 in the middle of the core mold 320 may be provided with a threaded hole 328, which is used for connecting two bolts 411 during the demolding process of the preform, and is convenient to hold when the core mold 320 is removed from the preform.
The cavity formed by the core mold 320 and the outer mold 400 is the desired preform geometry.
The connection fastening technique of the outer mold 400 is the prior art.
The length of the connected three components of the core mold is usually more than 70mm, so that the left and right components can form a box cavity to facilitate the clamping of a clamp, and therefore, the invention is more suitable for the box type prefabricated member with the inner cavity length more than 70 mm.
The molded surface of the bottom plate 405 of the shaping external mold 400 corresponds to the molded surface of the bottom of the box-shaped prefabricated member, and the molded surface of the bottom plate 405 is provided with through holes 407 which are used for discharging water vapor in the bottom of the prefabricated member in the processes of pre-shaping and shaping; the profiles of the shaping outer front template 401, the rear template 402, the left template 403 and the right template plate-shaped body 404 correspond to the profile of the side wall of the box-shaped prefabricated member, the top plate 406 corresponds to the top of the side wall of the box-shaped prefabricated member, and for discharging water vapor in the side wall of the box-shaped prefabricated member in the pre-shaping and shaping processes of the box-shaped prefabricated member, two exhaust structure designs are provided: one is that the width of the top plate body is smaller than the width of the inner cavity of the box preform so that the top of the sidewall of the long side 410 of the box preform is exposed, and the other is that the profile positions of the front mold plate 401, the rear mold plate 402, the left mold plate 403, and the right mold plate body 404 have through holes. In this embodiment, the mold bottom plate 405 has through holes 407 in the region corresponding to the bottom profile of the preform, and the top plate 406 has a width less than the width of the preform cavity, so that the tops of the two longer side walls 410 of the preform are exposed.
The size of the through holes 407 is suitable, if the aperture is too large, the hole spacing is too small, the flatness of the bottom surface of the box-type prefabricated member cannot be ensured, if the aperture is too small, the hole spacing cannot play a good role in removing water vapor, and the size and the spacing of the aperture are determined by the fineness of warp yarns and weft yarns of the carbon fiber cloth and the needle pitch and the row pitch. The ideal design is as follows: the diameter of the through holes 407 of the shaping external mold 400 is smaller than the sewing needle pitch and the line pitch, and the through hole pitch is larger than or equal to the sewing needle pitch and the line pitch and is smaller than or equal to 2 times of the sewing needle pitch and the line pitch.
In the present embodiment, it should be noted that the through holes with the hole diameter smaller than the needle pitch and the row pitch on the outer mold 400 do not affect the macroscopic three-dimensional box size of the final composite material product, and the deviation of the local surface flatness is eliminated in the process of the preform composite pressing or post-forming processing.
Preferred examples of the process according to the invention are given below for further details of the invention (see FIG. 1):
example 1
The sewing method and the shaping mold are adopted to manufacture the carbon fiber rectangular box prefabricated part with the bottom size of 150mm multiplied by 100mm, and the specific requirements are as follows: (1) the fiber volume content is higher than 50%; (2) the thickness of the bottom of the prefabricated part and the thickness of the four side walls are both 15 mm; (3) the height of the side wall is 55 mm; (4) the stitch length and the row spacing are 5 mm; (5) the angle of the layering is [0 degrees, 90 degrees ]; (6) the preform is used in a carbon/carbon composite material, each sidewall having substantially the same performance requirements; (7) the suture requirement is as follows: 2 ply T300 carbon fiber. The preform structure dimensions are shown in figure 1.
The sewing process of the carbon fiber box-type prefabricated member designed by the invention specifically comprises the following steps (see fig. 2):
firstly, cutting carbon fiber cloth with proper size and layer number according to the thickness and angle required by the prefabricated member and laying.
And (3) analysis: (1) in this embodiment, the carbon fiber cloth is selected as the following raw materials: the T300 plain cloth (2) containing the water-emulsion sizing agent is calculated according to the volume content of 55%, the layer density of the prefabricated member is 30 layers/cm through calculation according to relevant parameters of raw materials, the thickness of the side wall and the thickness of the bottom are the same and 15mm, and then 45 layers of carbon fiber cloth need to be cut. In this example, the sum of the length of the bottom of the preform and the height of the two side walls is 260mm, and the extension of the total height of the two side walls is 30mm, and 290mm is used, and the sum of the width of the bottom of the preform and the height of the two side walls is 210mm, and the extension of the total height of the bottom of the preform is 60mm (considering the wrapping manner of fig. 9(c) and 9(f) later, the excess is 270 mm). The fabric cutting angle is determined according to the required angle of the prefabricated member, in the embodiment, the ply angle is [0 degrees ], 90 degrees DEG]In particularThe sequence is as follows: [0 °,90 ° ]]22，0。
And cutting 0-degree 23 layers and 90-degree 22 layers of carbon fiber cloth sheets with the length of 290mm and the width of 240 mm. The method for laying the carbon fiber cloth 101 is to arrange the cut cloth 101 in the designed sequence of 0 DEG and 90 DEG]22The 0's are stacked in alignment, specifically the first 44 layers are 0's, alternating 90's, and the last 0's.
Second, the bottom of the box-type preform is sewn.
One lays the carbon fiber cloth 101 and sews the bottom 201 of the preform cavity in a completely penetrating manner, see fig. 3, with dimensions of 120mm x 70mm, with the center of the sewing area aligned with the center of the laminated carbon cloth, and the sewing effect is shown in fig. 4.
And (ii) sewing the corresponding bottom region 202 of the sidewall in a partially penetrating manner.
And (3) analysis: in this example, when the row pitch is 5mm at a side wall thickness of 15mm, the number of times of the partial penetration sewing is 2. The thickness of the bottom is the same as that of the side wall, layers cannot be added or reduced in the later wrapping process, one row spacing (5mm) of carbon fiber cloth is uncovered every time, and the thickness of a single layer of the carbon fiber cloth is 0.33mm, and 15 layers of the cloth are uncovered.
Therefore, the laminated carbon cloth is firstly stripped of 15 layers of carbon fiber cloth 203 along the periphery of the cavity bottom 201, and the remaining 30 layers of cloth 204 are sewn together at a position which is 5mm away from the horizontal line distance around the edge contour line 205 of the cavity bottom 201, as shown in fig. 5. In the same way, the 15 layers of cloth are opened again, and a circle of cloth is sewn again at a position which is 5mm away from the last circle which is just sewn, and the part of the cloth penetrates and is sewn twice. The effect of sewing the bottom surfaces of the carbon cloths before and after lamination is shown in fig. 6.
Thirdly, the carbon fiber cloth with the two-dimensional laminated structure is wrapped into a three-dimensional box-shaped structure by using a forming core mold.
The forming mandrel 320 is placed directly over the fully through stitched preform bottom 201 and the contour 301 of the mold is aligned with the fully through stitched central region 201 along contour 205, as shown in fig. 7. The core mold 320 is formed by connecting three members, and the left side member 321 and the right side member 323 have a box-shaped structure and have a sidewall thickness of 7 mm. The intermediate plate section 322 is tapered to a thickness of 9.5mm on the underside and 10mm on the upper side (to facilitate insertion between the left and right side members 321, 323 during clamping). The three parts of the die are connected and fixed through two groups of bolts 324 and nuts 325, the material of the die is 6061 type hard aluminum, and the molded surface of the die is pasted with polytetrafluoroethylene demolding cloth 326 (the molded surface of the outer die 400 is also pasted with the demolding cloth). The intermediate plate-shaped body has two positioning pin holes 327 for positioning between the core mold 320 and the outer mold 400. Also, the intermediate plate profile has two threaded holes 328 for attaching two bolts during the stripping of the preform, which facilitate gripping during removal from the preform, as shown in fig. 8 for the core mold.
The areas 305 of the carbon cloth near the four corners surrounded by the extension lines 303 of the cavity bottom area 201 of the first three layers of the core mold 320 and the contour lines 304 of the carbon cloth are cut off as shown in fig. 9(a), and then the remaining part 306 is lifted up to be attached to the mold surface of the mold as tightly as possible without wrinkles as shown in fig. 9 (b). And (3) the redundant selvedges of the erected carbon fiber cloth are laked in the inner cavity of the core mold, the erected carbon fiber cloth is clamped on the side wall of the core mold by a clamp, and the fracture of the wrapping method is positioned at four corners of the side wall of the box-shaped prefabricated member. The four corners of the erected carbon cloth are pre-sewn together at the adjacent two sides by nylon threads 307 with the fineness of 450D, as shown in fig. 10. The sewing is used for fixing the carbon cloths at two sides together, the distance between a sewing needle hole 308 and the cloth edge is 12 +/-1 mm in a cross sewing mode, and the nylon thread 307 is used for pre-sewing the joint after one layer or one group of carbon cloths are wrapped.
And (4) wrapping layers 4 to 6 of the carbon cloth, cutting off an area 311 surrounded by two extension lines 309 parallel to two bottom edges of the bottom area of the prefabricated part and a contour line 310 of the carbon cloth, and then properly cutting off four rectangular corners 312 of the rest cloth pieces, as shown in fig. 9(c) and 9 (d). The remaining cloth pieces 313 are erected and attached to the previously wrapped 1-3 layers of carbon fiber cloth 306, the selvedges of the erected carbon fiber cloth are pressed into the inner cavity of the core mold, and the carbon fiber cloth pieces are clamped on the side wall of the core mold by using the clamps. The redundant parts 314 of the cloth pieces on the two sides of the carbon fiber are folded and attached to the side walls of the other two core moulds, the joints 315 are aligned and clamped by clamps, the joints 315 are sewn by using a cross sewing mode through nylon threads 307, the distance between a sewing needle hole 308 and the cloth edge is 12 +/-1 mm, and the sewing tension is moderate.
And 7 th to 9 th layers of the carbon cloth are wrapped by the same method as the second wrapping method, but the operation direction is rotated by 90 degrees, as shown in fig. 9(e) and 9 (f).
The box-shaped preform side wall carbon cloth of the embodiment has 45 layers, one group of three layers and fifteen groups, the three wrapping methods can be repeated for 5 cycles, in order to improve the appearance of the fabric, the first wrapping method (the method that the fracture is at the corner) in the last cycle can be placed at the end to be used as the last group of wrapping, and the sequence of the rest cycles is not changed.
Fourthly, pre-shaping the wrapped semi-finished product of the prefabricated member.
The wrapped preform fabric is removed from the clip, and since the height of the sidewall of the mandrel 320 is the height of the inner sidewall of the box-shaped preform, the excess burrs are trimmed off with scissors, so that the height of the sidewall is flush with the height of the mandrel 320. And then uniformly spraying distilled water to the fabric, wherein the spraying amount of the distilled water is about 300g, and lightly pressing the side wall of the carbon fiber fabric prefabricated part to thoroughly wet the fabric. Then, an outer mold 400 is installed, and the outer mold 400 is formed by combining and connecting six plate-shaped bodies, namely a front mold plate 401, a rear mold plate 402, a left mold plate 403, a right mold plate 404, a bottom plate 405 and a top plate 406, as shown in fig. 11. Wherein the area of the bottom plate 405 contacting the bottom of the preform is provided with holes 407 having a diameter of 3mm and a hole pitch of 7 mm. The top plate 406 has two positioning pin holes 408 for positioning pins 409 between the top plate 406 and the core mold 320, and the top plate 406 has a width of 70mm smaller than the width of the preform inner cavity so as to expose the tops of the two longer side walls 410 of the preform. As shown in fig. 12. After the die assembly and the installation are finished, the whole die (containing the prefabricated part) is placed on a grid of a vacuum drying box for heating, so that the small holes 407 of the die bottom plate are not blocked for facilitating the discharge of moisture, the heating temperature is 120 ℃, and the time is 1.5 hours. During drying of the fabric preform, moisture from the sidewalls may be emitted from the top end 410 and moisture from the bottom of the preform may be emitted from the small holes 407 in the mold bottom. And after the mold is naturally cooled, taking out the mold, and taking out the prefabricated part from the mold. The mold opening method comprises the following steps: first, the bolts connecting the outer mold 400 are unscrewed, and the positioning pins 408 are removed; the external mold 400 is disassembled to obtain six plate-shaped bodies; then two bolts 411 are screwed into the threaded holes 328 of the core intermediate plate profile, the intermediate plate profile 322 is pulled out by pulling the two bolts 411, as shown in fig. 13, and the box-shaped members 321 and 323 on both sides are taken out.
Fifth, side wall of box-type preform
The side wall of the box-type prefabricated member is divided into three steps, namely a bottom end 501 of the side wall of the box-type prefabricated member, a middle part 502 of the side wall of the box-type prefabricated member and four corners 503 of the box-type prefabricated member, and the three steps correspond to three areas, and refer to fig. 14.
First, the bottom end 501 of the preform side wall is seamed, with the first row seamed from the corner 504 of the bottom edge of the box. The needle pitch and the row pitch on the outer side of the box-shaped preform are both 5mm, the needle pitch on the inner side of the box-shaped preform is controlled to be 0.8 to 2mm, a region 505 with 3mm near the edge line of the inner edge of the box is sewed, and the section condition of the penetrated suture is shown in a figure 2 (f). In this example, the thickness of the bottom of the preform is 15mm, and the gauge is 5mm, then 3 rows of stitches are needed at the bottom of the preform. Second, the seam preform sidewall middle portion 502, both inside and outside gauge, and row spacing were 5 mm. Finally, sewing the four corners of the prefabricated member, controlling the outside needle pitch and the row pitch of the box-shaped prefabricated member to be 5mm, controlling the inside needle pitch to be 0.8-2 mm, sewing an area 506 which is 3mm near the side line of the inner edge of the box, and showing the section condition of the penetrating suture line by referring to fig. 2 (h).
Sixthly, forming the box-shaped prefabricated member
And after the four side walls of the prefabricated member are completely sewed, carrying out final shaping on the prefabricated member. Firstly, installing a mould, firstly placing the left side member 321 and the right side member 323 of the core mould 320 into corresponding two side positions in the box-shaped prefabricated member, then inserting the middle plate-shaped body 322 into the middle of the two box-shaped bodies of the left side member 321 and the right side member 323, lightly knocking the middle plate-shaped body 322 by a small wooden hammer in the inserting process, and scratching a suture line of a side wall after the plate-shaped body 322 is prevented from being excessively inclined. The preform was then sprayed again uniformly with distilled water, in an amount of about 300g, gently pressing the side walls of the carbon fiber fabric preform to wet through the fabric. Finally, the outer die 400 of the die is installed by using related positioning pins, bolts and the like, and die assembly is completed.
The mold (containing the box-shaped preform) was placed in a vacuum oven and heated at 120 ℃ for 2.5 hours. And after the mould is heated and naturally cooled, opening the mould, wherein the method is the same as the method for opening the mould for presetting. The fabric obtained after trimming the raw edges of the preform side walls is the desired preform, as shown in fig. 2 (i).
Example 2
The sewing method and the shaping mold are adopted to manufacture the carbon fiber rectangular box prefabricated part with the bottom size of 150mm multiplied by 100mm, the thickness of the bottom of the prefabricated part is 15mm, and the thickness of the side wall of the prefabricated part is 10 mm. The height of the side wall is 55mm, the thickness of the single layer of the carbon fiber cloth is 0.33mm, and the stitch length and the row spacing are 5 mm. The ply angle was [0 °,90 ° ].
And (3) analysis: the box-shaped preform is required to be thinner than the bottom in comparison with the case of example 1, so that the side wall needs to be removed by 5 divided by 0.33 to be 15 layers of carbon cloth, and the sewing method is different from the example mainly in two steps: the side wall region of the bottom and the three-dimensionally wrapped box-type preform are sewn in a partially penetrating manner.
Sewing the side wall region of the bottom in a partially penetrating manner: in this step, the 22 pieces of cloth are peeled off from the periphery of the laminated carbon cloth sewed in the central area, because 7 pieces of cloth in the 22 pieces of cloth are cut off in the process of wrapping the rear part, actually, the number of the side wall layers corresponding to the 22 pieces of cloth is 15 finally, and then the rest 23 pieces of cloth (the number of the side wall layers is 15 finally) are sewed for one circle around the position of one needle pitch of the edge outline of the central area sewed in the distance complete penetration mode. The suture is not completely penetrated once.
Three-dimensional parcel box type prefab: the prefabricated part is totally 45 layers of cloth, the thickness of the side wall is 10mm, 15 layers of cloth need to be cut off, every 3 layers of the 45 layers of cloth are divided into 15 groups, three layers of cloth in each group are wrapped with two layers, one layer is cut off, 0 degree is cut off in odd groups, adjacent 90 degrees is cut off in even groups, and the rest cloth still keeps the layering sequence of 0 and 90 degrees. The cloth was cut off for the entire root of the area sewn around the bottom of the box, and the rest of the wrapping was performed in the manner described in example 1.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the claims. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that the present invention may be embodied with insubstantial modifications or equivalents without departing from the spirit of the embodiments of the present invention, and the scope of the claims is to be determined by the equivalents of the embodiments.
Claims (7)
1. A method of sewing a carbon fiber box-type preform, the method comprising the steps of: firstly, cutting carbon fiber cloth according to the design size and the lamination angle of a box-type prefabricated part and laying; secondly, sewing the bottom of the inner cavity of the box-shaped prefabricated part in a completely penetrating manner; sewing the bottom corresponding to the side wall of the box-shaped prefabricated part in a partially penetrating mode; thirdly, wrapping the carbon fiber cloth with the two-dimensional laminated structure into a three-dimensional box-shaped structure by using a forming core mold; fourthly, uniformly spraying distilled water on the box-shaped prefabricated member to thoroughly wet the box-shaped prefabricated member, and heating and pre-shaping the box-shaped prefabricated member by using a shaping mold; fifth, the sidewall of the box-type preform is sewn in a completely penetrating manner; sixthly, uniformly spraying distilled water on the box-shaped prefabricated member again to enable the box-shaped prefabricated member to be thoroughly wetted, and then heating and shaping the box-shaped prefabricated member by using a shaping mold to obtain the finished product;
the partially penetrating sewing method is characterized in that the number of layers required by the process is uncovered from the laminated carbon fiber cloth at the bottom of the inner cavity of the sewn box-type prefabricated part, and a circle of the remaining carbon fiber cloth is sewn at the position with the horizontal distance of the outer contour line of the sewn area as a line pitch, namely, one-time partially penetrating sewing is completed; the number of partial penetrating and sewing is that the thickness of the side wall of the box-shaped prefabricated member is divided by the line spacing and then is reduced by 1, and if the obtained number of times is not an integer, the number of times is rounded;
the method for wrapping the box-type prefabricated member comprises the steps of cutting a layer or a group of carbon fiber cloth in a three-dimensional mode, removing redundant carbon fiber cloth, lifting and folding the reserved carbon fiber cloth, attaching the reserved carbon fiber cloth to the molded surface of the forming core mold or wrapping the carbon fiber cloth on the forming core mold without folds, clamping the erected carbon fiber cloth on the side wall of the forming core mold by a clamp, pre-sewing the butt joint by a pre-sewing thread, repeatedly cutting and wrapping until all the carbon fiber cloth is wrapped on the forming core mold, and achieving the side wall thickness required by the prefabricated member;
the heating temperature for presetting is 80-150 ℃, and the heating time is 0.5-2 hours;
the heating temperature for shaping is 80-150 ℃, and the heating time is 0.8-3 hours;
the specific number of layers required by the uncovering process needs to consider a wrapping method, so that the thickness of the uncovered carbon fiber cloth wrapped on the side wall after related wrapping operation is just one line spacing;
the pre-sewing operation method is that a pre-sewing thread with the fineness lower than the carbon fiber cloth warp and weft is used for sewing 4 to 20 needles of the butt joint so as to fix the butt joint together; the material of the pre-sewing line is carbon fiber or a material which can be decomposed in the final composite process of the box-type prefabricated member.
2. A shaping mold suitable for the sewing method of the carbon fiber box-type preform as claimed in claim 1, characterized in that the shaping mold comprises a shaping external mold and a shaping core mold, the shaping core mold is a box-shaped body formed by sequentially connecting and fastening three detachable components, the connecting direction is the length direction of the box-type preform, and the outer wall profile of the shaping core mold is the profile of the inner cavity of the box-type preform; the three components of the forming mandrel are: a plate-shaped body member, two box-shaped body members, the plate-shaped body member is positioned in the middle, and the two box-shaped body members are positioned at two sides of the middle plate-shaped body member and connected;
the shaping outer die is a box-shaped body formed by connecting and assembling six plate-shaped bodies, namely a front template, a rear template, a left template, a right template, a top template and a bottom template, and the molded surface of the inner wall of the box-shaped body is the molded surface of the outer wall of the box-shaped prefabricated member; the shaping external mold is matched with the shaping core mold, so that the shaping core mold coated with the carbon fiber cloth can be arranged in the shaping external mold; the molded surface of the bottom plate molded body of the shaping outer mold corresponds to the molded surface of the bottom of the box-shaped prefabricated part, and the molded surface of the bottom plate molded body is provided with through holes for discharging water vapor in the bottom of the prefabricated part in the pre-shaping and shaping processes; the profile of design external mold front formword, back template, left template and right template plate type body corresponds the profile of box type prefab lateral wall, and the plate type body of top template corresponds the top of box type prefab lateral wall, for making the box type prefab in the steam in the box type prefab lateral wall of preforming and design in-process discharge, there are two kinds of exhaust structural design: one structure is that the width of the top template is smaller than that of the inner cavity of the box-type prefabricated member, so that the top of the long side wall of the box-type prefabricated member is exposed for exhausting; the other structure is that the molded surfaces of the front template, the rear template, the left template and the right template are provided with through holes for exhausting.
3. The forming die of claim 2, wherein the diameter of the through holes of the outer forming die is smaller than the stitch pitch and the row pitch of the sewing, and the distance between the through holes is greater than or equal to the stitch pitch and the row pitch of the sewing and is less than or equal to 2 times of the stitch pitch and the row pitch.
4. The sizing die as set forth in claim 2, wherein the slab member of the forming core has a taper such that a lower end thereof has a small thickness and an upper end thereof has a large thickness.
5. The shaping mold according to claim 2, wherein a high temperature-resistant release tape is attached to the surface of the shaping mold contacting the preform.
6. The sizing die according to claim 2, wherein two positioning pin holes are reserved on the upper end surface of the intermediate plate-shaped body of the forming core die.
7. The sizing die according to claim 2, wherein two threaded holes are reserved in the upper end surface of the intermediate plate-shaped body of the forming core die.
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| CN108274767B (en) * | 2018-04-02 | 2020-05-12 | 天津工业大学 | Sewing mold and method for strip-shaped composite material preformed body |
| CN111016003B (en) * | 2019-12-13 | 2021-09-07 | 西安鑫垚陶瓷复合材料有限公司 | Shaping tool and C/SiC composite material structural member forming method using same |
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