1. Supplementary mould, including outer frame body, its characterized in that: the outer frame body is a rectangular frame-shaped structure formed by two groups of metal rods which are oppositely arranged, and the foam core material strips are arranged on the inner side of the rectangular frame-shaped structure along the length direction; wherein, be provided with two locating component on longer a set of metal pole relatively, this locating component includes a plurality of locating pieces that set up along the length direction interval of metal pole, and the locating piece setting is in the inboard of metal pole, and the cross section of two tip of foam core strip is the same with the shape and the size of locating piece, and foam core strip alternate distribution between two locating pieces that set up relatively and between two adjacent locating pieces.

2. An auxiliary mold according to claim 1, wherein: the positioning block is provided with an ear seat on the end face close to one side of the metal rod, the metal rod is provided with a blind hole matched with the ear seat, and the positioning block is installed on the metal rod through the ear seat.

3. An auxiliary mold according to claim 2, wherein: the metal rods are connected with the lug seats and the two groups of metal rods which are oppositely arranged through locking bolts.

4. An auxiliary mold according to claim 1, wherein: the bottom of at least one group of metal rods arranged oppositely is provided with a detachable pin with adjustable height.

5. A method for preparing a grid structure reinforced foam sandwich composite material by using the auxiliary mould of any one of claims 1 to 4, which is characterized by comprising the following steps:

step 1), forming an outer frame body by a rectangular frame-shaped structure surrounded by two groups of metal rods which are arranged oppositely, and installing two rows of positioning assemblies and pins on the outer frame body to form the auxiliary die;

step 2), placing the assembled auxiliary mold on the lower panel in the middle, pressing the auxiliary mold downwards to apply pressure, enabling the pin to leave an indentation on the lower panel, removing the auxiliary mold, forming a hole at the indentation, and assembling the auxiliary mold above the lower panel through the pin;

step 3), sequentially laying foam core material strips on the inner sides of a plurality of groups of oppositely arranged positioning blocks at intervals;

step 4), laying the dry fiber fabric above the foam core material strips laid at intervals, then prepressing downwards by using a plurality of foam core material strips to extrude the foam core material strips into gaps of the foam core material strips laid at intervals, and placing a heavy object on the foam core material strips to fix and compact the foam core material strips and the dry fiber fabric;

step 5), removing the heavy object, and paving a panel right above the foam core material strip and the dry fiber fabric to form a preformed body;

step 6), sequentially performing demoulding cloth, flow guide net laying and glue injection pipeline arrangement in the preformed body according to a VARI forming process, and then integrally packaging the preformed body by using a vacuum bag film;

and 7) injecting glue into the packaged preformed body according to a VARI forming process, unloading the auxiliary mould around the reinforced foam sandwich composite material product after the resin is completely cured, and demoulding.

6. The method of claim 5, wherein in the step 4), if the cross section of the foam core material strip is not rectangular, the foam core material strip is cut to fill the gap between the two ends of the auxiliary mold after the plurality of foam core material strips are extruded into the gap.

7. The manufacturing method according to claim 5, wherein the step 3) aligns both ends of the foam core material strip with the positioning blocks on both sides thereof, respectively, when the foam core material strip is laid.

8. The manufacturing method according to claim 5, wherein the peripheries of the upper and lower face plates each extend outward by 5mm or more with respect to the auxiliary mold.

Background

The traditional foam sandwich composite material is formed by compounding upper and lower composite material panels with higher strength and modulus and a low-density foam sandwich material between the upper and lower panels, and has higher specific strength and specific rigidity; meanwhile, the low-density foam sandwich material has the functions of fire prevention, heat insulation, sound insulation, energy absorption and the like. Therefore, the traditional foam sandwich composite material becomes a typical structure and function integrated material and is widely applied to the fields of rail transit, high-speed trains, aerospace, ships, ocean engineering and the like. However, with the continuous improvement of the requirements of engineering application on structural performance, the traditional foam sandwich composite material can not meet the requirements. And introduce the composite material grid structure into the foam core material of the traditional foam core composite material, construct a new sandwich structure composite material-grid structure reinforced foam core composite material, its main body part is the traditional foam core composite material, the reinforcement part is the composite material grid structure, therefore, grid structure reinforced foam core composite material has integrated the advantages of traditional foam core composite material and composite material grid structure, not only retained the advantages of lower density, higher strength, higher modulus of traditional foam core composite material, but also exerted the outstanding mechanical properties of composite material grid structure, namely: on the premise that the overall density is slightly increased, the mechanical properties of the grid structure reinforced foam sandwich composite material such as flat pressure, side pressure, bending, shearing and the like are obviously improved, and particularly the side pressure property is increased by multiple times.

Due to the introduction of composite grid structures, the foam core board, originally as a whole, was divided into individual discrete foam core strips. When the interlayer preforming body is prepared, dry-state fiber fabrics (which are composite material grid structures after resin infiltration molding) and foam core material strips are alternately laid, the dry-state fiber fabrics are inserted among the discrete foam core material strips in a wave shape, the foam core material strips are 'semi-coated' by the dry-state fiber fabrics, and the geometric shape of the dry-state fiber fabrics is an anti-symmetric structure. In order to improve the fitting degree between adjacent foam core material strips and between the foam core material strips and the dry-state fiber fabric as much as possible and reduce local wrinkles of the dry-state fiber fabric as much as possible, a certain tension is required to be applied to the dry-state fiber fabric, and the foam core material strips attached to the dry-state fiber fabric are broken out due to the fact that the density of the foam core material is low (less than or equal to 400kg/m 3) through the antisymmetric structure dry-state fiber fabric with a certain tension. In addition, even if the foam core material strips and the dry fiber fabric are alternately laid according to the operation, the preformed body which is originally well jointed can be loosened again, so that the prepared laminated preformed body is irregular in arrangement, uneven in overall thickness and uneven in thickness of the grid structure, and the appearance size and quality consistency of the grid structure reinforced foam sandwich composite material are influenced.

Disclosure of Invention

In view of the above, the present invention provides an auxiliary mold and a method for preparing a grid structure reinforced foam sandwich composite material, so as to solve the above technical problems.

In order to achieve the purpose, the invention adopts the technical scheme that: the auxiliary mould comprises an outer frame body, wherein the outer frame body is a rectangular frame-shaped structure formed by two groups of metal rods which are oppositely arranged, and foam core material strips are arranged on the inner side of the rectangular frame-shaped structure along the length direction; wherein, be provided with two locating component on longer a set of metal pole relatively, this locating component includes a plurality of locating pieces that set up along the length direction interval of metal pole, and the locating piece setting is in the inboard of metal pole, and the cross section of two tip of foam core strip is the same with the shape and the size of locating piece, and foam core strip alternate distribution between two locating pieces that set up relatively and between two adjacent locating pieces.

Furthermore, the end face of the positioning block, which is close to one side of the metal rod, is provided with an ear seat, the metal rod is provided with a blind hole matched with the ear seat, and the positioning block is installed on the metal rod through the ear seat.

Furthermore, the metal rods and the lug seats and the two groups of metal rods which are oppositely arranged are connected through locking bolts.

Furthermore, the bottom of at least one group of metal rods arranged oppositely is provided with a pin which can be detached and has adjustable height.

The preparation method of the grid structure reinforced foam sandwich composite material uses the auxiliary mould to prepare the composite material, and comprises the following steps:

step 1), forming an outer frame body by a rectangular frame-shaped structure surrounded by two groups of metal rods which are arranged oppositely, and installing two rows of positioning assemblies and pins on the outer frame body to form the auxiliary die;

step 2), placing the assembled auxiliary mold on the lower panel in the middle, pressing the auxiliary mold downwards to apply pressure, enabling the pin to leave an indentation on the lower panel, removing the auxiliary mold, forming a hole at the indentation, and assembling the auxiliary mold above the lower panel through the pin;

step 3), sequentially laying foam core material strips on the inner sides of a plurality of groups of oppositely arranged positioning blocks at intervals;

step 4), laying the dry fiber fabric above the foam core material strips laid at intervals, then prepressing downwards by using a plurality of foam core material strips to extrude the foam core material strips into gaps of the foam core material strips laid at intervals, and placing a heavy object on the foam core material strips to fix and compact the foam core material strips and the dry fiber fabric;

step 5), removing the heavy object, and paving a panel right above the foam core material strip and the dry fiber fabric to form a preformed body;

step 6), sequentially performing demoulding cloth, flow guide net laying and glue injection pipeline arrangement in the preformed body according to a VARI forming process, and then integrally packaging the preformed body by using a vacuum bag film;

and 7) injecting glue into the packaged preformed body according to a VARI forming process, unloading the auxiliary mould around the reinforced foam sandwich composite material product after the resin is completely cured, and demoulding.

Further, in the step 4), if the cross section of the foam core material strip is not rectangular, after the plurality of foam core material strips are squeezed into the gap, the foam core material strips are cut to fill the gap at the two ends of the auxiliary mold.

Further, in the step 3), when the foam core material strip is laid, two ends of the foam core material strip are respectively aligned with the positioning blocks positioned on two sides of the foam core material strip.

Furthermore, the periphery of the upper panel and the periphery of the lower panel extend outwards for more than 5mm relative to the auxiliary die.

Compared with the prior art, the invention has the beneficial effects that:

firstly, the position of the foam core material strip and the thickness of the grid structure can be accurately controlled through the design of the positioning block, and the problems of accurate control of the size of a preformed body, control of the whole thickness, stability of the preformed body, consistency of the forming quality and the like in the forming process of the grid structure reinforced foam sandwich composite material can be effectively solved;

secondly, by taking the thickness of the panel of the grid structure reinforced foam sandwich composite material as a reference and through the matching design of the detachable and height-adjustable pins at the bottom of the metal rod, the thickness of the lower panel and the consistency between the lower panel and the upper panel can be well controlled;

thirdly, after the preparation of the whole preformed body is finished, laying demolding cloth, a flow guide net, a glue injection port, a glue outlet, a glue injection pipeline and the like according to the conventional steps of a VARI molding process, then integrally packaging, realizing the integrated integral molding of the upper panel, the lower panel and the interlayer preformed body, disassembling an auxiliary mold and pins around the grid structure reinforced foam sandwich composite material product, and demolding to obtain the grid structure reinforced foam sandwich composite material;

fourthly, the auxiliary mould has lower manufacturing cost, can be repeatedly used, is easy to demould, disassemble and assemble and is easy to maintain;

fifthly, the integrated integral forming process is the same as the conventional VARI forming process, the process technology is mature and stable, the process flow is simple, the product can be obtained through one-step forming, and the preparation efficiency, the appearance quality and the quality consistency are obviously improved;

and sixthly, the shape and the thickness of the grid structure can be accurately controlled by reasonably designing the shapes of the positioning blocks and the distance between the adjacent positioning blocks, so that the preparation of the reinforced foam sandwich composite material with different types of grid structures is realized.

Drawings

FIG. 1 is a schematic structural view of an auxiliary mold according to the present invention;

FIG. 2 is a cross-sectional view of a preform at one of its cross-sections;

FIG. 3 is a cross-sectional view of a preform at another cross-section;

FIG. 4 is a cross-sectional view of the preform after the lower panel has been removed;

FIG. 5 is a schematic illustration of the process of laying down foam core strips when the foam core strips are rectangular;

FIG. 6 is a schematic illustration of a process for laying down foam core strips when the foam core strips are non-rectangular, such as isosceles trapezoids;

FIG. 7 is a schematic view of the distribution of positioning blocks on a first rectangular cross-section metal bar when the foam core strip is rectangular;

FIG. 8 is a schematic view of the distribution of locating blocks on a first rectangular cross-section metal bar when the foam core strip is non-rectangular, such as an isosceles trapezoid;

the labels in the figure are: 1. the composite material comprises a first rectangular-section metal rod, a second rectangular-section metal rod, a positioning block, a first locking bolt, a second locking bolt, a pin, a first locking bolt, a second locking bolt, a first locking bolt, a second locking bolt, a foam core material strip, a dry-state fiber fabric, a second locking bolt, a foam core material, a second locking bolt, a third locking bolt, a fourth rectangular-shaped metal bar.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments, and all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

An auxiliary mold, which includes an outer frame body, as shown in fig. 1, the outer frame body is a rectangular frame-shaped structure surrounded by two sets of metal rods arranged oppositely, and the foam core material strips 8 are arranged along the length direction at the inner side of the rectangular frame-shaped structure; in the invention, two groups of metal rods which are oppositely arranged comprise a group of first rectangular section metal rods 1 which are parallelly and oppositely arranged and a group of second rectangular section metal rods 2 which are parallelly and oppositely arranged, wherein the first rectangular section metal rods 1 are longer metal rods, two rows of positioning components are oppositely arranged on the longer group of metal rods, each positioning component comprises a plurality of positioning blocks 3 which are arranged at intervals along the length direction of the metal rods, the positioning blocks 3 are arranged on the inner sides of the first rectangular section metal rods 1, as shown in figures 2-4, the cross sections of two end parts of a foam core material strip 8 are the same as the positioning blocks 3 in shape and size, and the foam core material strips 8 are alternately distributed between the two positioning blocks 3 which are oppositely arranged and between the two adjacent positioning blocks, so that the inner sides of a rectangular frame-shaped structure are closely arranged along the length direction. Through the design of the positioning block and the positioning assembly, the position of the foam core material strip and the thickness of the grid structure can be accurately controlled, and the problems of accurate control of the size of a preformed body, control of the whole thickness, stability of the preformed body, consistency of the forming quality and the like in the forming process of the grid structure reinforced foam sandwich composite material can be effectively solved; and the shape of the positioning blocks and the distance between the adjacent positioning blocks are reasonably designed, so that the shape and the thickness of the grid structure can be accurately controlled, and the preparation of different types of grid structure reinforced foam sandwich composite materials is realized.

Furthermore, an ear seat is arranged on the end face of the positioning block 3 close to one side of the first rectangular-section metal rod 1, a blind hole matched with the ear seat is formed in the first rectangular-section metal rod 1, and the positioning block 3 is installed on the first rectangular-section metal rod 1 through the ear seat. The first metal rod 1 with the rectangular cross section is connected with the lug seat and the two groups of metal rods which are oppositely arranged through a first locking bolt 4 and a second locking bolt 5.

Further, the bottom of at least one group of metal rods arranged oppositely is provided with a pin 6 which can be detached and adjusted in height.

The auxiliary die is low in manufacturing cost, can be repeatedly used, is easy to demould, disassemble, assemble and maintain.

The preparation method of the grid structure reinforced foam sandwich composite material uses the auxiliary mould to prepare the composite material, and specifically comprises the following steps:

(1) the metal rod is pretreated, the outer surfaces, the bottom circular blind holes, the side rectangular blind holes and the like of the first rectangular-section metal rod 1 and the second rectangular-section metal rod 2 are wiped clean by alcohol or acetone, the metal rods are aired for about 5 minutes, and then demolding wax is uniformly coated for 3 times, wherein the interval is about 15 minutes each time.

(2) The pins are assembled, the pins 6 are round metal pins, the number of the pins is not less than 3, the surfaces of the pins are wiped clean by alcohol or acetone, the pins are dried for about 5 minutes, and then demolding wax is uniformly coated for 3 times, wherein the interval between every two times is about 15 minutes. And finally, slowly inserting the processed pin 6 into the round blind hole in the bottom surface of the first rectangular-section metal rod 1 to ensure that the pin and the round blind hole are well occluded.

(3) The positioning blocks are assembled, the outer surfaces of the positioning blocks 3 (including the lug seats with rectangular side surfaces) are cleaned by alcohol or acetone before installation, the positioning blocks are dried for about 5 minutes, then demolding wax is uniformly coated for 3 times, the interval is about 15 minutes every time, and each positioning block 3 needs to be processed according to the steps. Then, the processed positioning blocks 3 are sequentially and slowly inserted into the rectangular blind holes in the side face of the first rectangular-section metal rod 1, so that the lug seats are well occluded with the rectangular blind holes. The first locking bolt 4 is a countersunk bolt, and is screwed into a blind hole in the side surface of the first rectangular-section metal rod 1 after penetrating through a through hole in the width direction of the positioning block 3. When the first locking bolt 4 is installed, the first locking bolt is not over screwed, and the positioning block 3 is not shaken.

(4) The rectangular frame-shaped structure is assembled, and the rectangular frame-shaped structure is formed by combining a group of identical first rectangular-section metal rods 1 and a group of identical second rectangular-section metal rods 2. In this embodiment, tenons are processed at two ends of the first rectangular-section metal rod 1, and are connected and fixed with the second rectangular-section metal rod 2 in a similar tenon joint manner, and the second locking bolt 5 is also a countersunk bolt for locking the first rectangular-section metal rod 1 and the second rectangular-section metal rod 2.

(5) And (3) laying a lower panel, determining the number of layers, laying modes and the like of the fiber fabric to be laid according to the target thickness of the panel and the type of the selected reinforced fiber fabric, wherein the length and the width of the fiber fabric are larger than the peripheral dimension of the assembled rectangular frame-shaped structure by more than 5 mm.

(6) And (3) performing a lower panel hole opening process, namely placing the assembled rectangular frame-shaped structure on the lower panel 10 in the center, slightly applying pressure to make the pins 6 leave marks on the lower panel 10, then removing the rectangular frame-shaped structure, and opening holes at the marks by using a punch or other tools, wherein the hole diameter is more than 1mm larger than the diameter of the pins 6.

(7) Laying of foam core material strips, wherein the cross sections of the foam core material strips 8 are identical to the shapes and the sizes of the positioning blocks 3, the foam core material strips 8 are laid at intervals from one side to the other side when being laid, the two ends of the first foam core material strip 8 are aligned with the first pair of positioning blocks 3 positioned on the two sides of the first foam core material strip, and the rest is done until the foam core material strips 8 matched with all the paired positioning blocks 3 are laid.

(8) And (2) paving dry fiber fabrics, wherein the dry fiber fabrics 9 are formed into a composite material grid structure after being soaked and molded by resin, paving the dry fiber fabrics 9 on neat foam core material strips 8 which are paved at intervals, then prepressing downwards by using a plurality of foam core material strips 8 to extrude the dry fiber fabrics into gaps of the foam core material strips 8 which are paved at intervals, and timely placing strip-shaped weights on the dry fiber fabrics to fix and compact the foam core material strips 8 and the dry fiber fabrics 9. Fig. 5 and 6 are respectively: the schematic diagram of the laying process of the foam core material strips is shown when the foam core material strips are rectangular and isosceles trapezoid; accordingly, fig. 7 and 8 are respectively: when the foam core material strip is rectangular or isosceles trapezoid, the distribution of the positioning blocks on the first metal rod 1 with the rectangular section is schematically shown.

(9) And (3) laying an upper panel, removing the strip-shaped heavy object, laying the upper panel 7, wherein the laying requirement is the same as that of the lower panel 10, and forming a preformed body.

(10) For the foam core material strip with the non-rectangular section, the foam core material strip 8 is cut to fill the gap parts at the two ends of the rectangular frame-shaped structure, so that the preforming body is filled in the rectangular frame-shaped structure; for a rectangular cross-section foam core strip, this step is omitted.

(11) And (3) packaging the preformed body, namely, performing demolding cloth, laying a flow guide net and arranging a glue injection pipeline according to a VARI (vacuum infiltration RI) forming process, and then integrally packaging the preformed body by using a vacuum bag film.

(12) And (3) injecting glue and demolding, namely injecting glue into the packaged preformed body according to a VARI (vacuum amorphous alloy) forming process, and demolding after the first rectangular-section metal rod 1, the second rectangular-section metal rod 2 and the pin 6 around the grid-structure reinforced foam sandwich composite material product are disassembled after the resin is completely cured.

In this embodiment, the first rectangular-section metal rod 1 and the second rectangular-section metal rod 2 are made of 45# steel, higher-grade steel, aluminum alloy or titanium alloy, and the like, the length of the first rectangular-section metal rod 1 is the same as the target length of the grid structure reinforced foam sandwich composite material, i.e., the length is less than or equal to 5m, the width is related to the modulus of the selected material, the flexibility of the rectangular-section metal rod is less than or equal to 2mm, generally not less than 20mm, and the height is the same as the thickness of the foam core material (less than or equal to 200 mm); the length of the second rectangular section metal rod 2 is the same as the target width of the grid structure reinforced foam sandwich composite material, namely the width is less than or equal to 5m, and the width and the height are the same as those of the first rectangular section metal rod 1. In addition, the diameter of the round blind hole in the bottom surface of the first rectangular-section metal rod 1 is one fourth to one half of the width of the metal rod, the machining tolerance is +/-0.1 mm, the center position of the round blind hole is the middle point of the width of the rectangular-section metal rod 1, and the number of the round blind holes is not less than 3 and is uniformly distributed along the length direction of the bottom surface of the first rectangular-section metal rod 1.

The specification of the pin 6 is M4-M16, the material is 45# steel, higher grade steel, aluminum alloy or titanium alloy and other metals, the diameter of the pin is 0.1-0.2mm smaller than that of the round blind hole on the bottom surface of the first rectangular section metal rod 1, the processing tolerance is +/-0.1 mm, and the length of the exposed bottom surface of the first rectangular section metal rod 1 is the same as the thickness of the panel of the grid structure reinforced foam sandwich composite material. By taking the thickness of the panel of the grid structure reinforced foam sandwich composite material as a reference and through the matching design of the detachable and height-adjustable pins at the bottom of the metal rod, the thickness of the lower panel and the consistency of the lower panel and the upper panel can be well controlled.

The number of the positioning blocks 3 is required to be 2N (N is more than or equal to 2 and less than or equal to 100, N is an integer), the length range is 10mm-100mm, the width range is 8mm-50mm, the height range is 10mm-70mm, and the distance between every two adjacent positioning blocks 3 is +/-1 mm of the length of the positioning blocks 3; in addition, all the positioning blocks 3 are completely the same in appearance size and material, the material is 45# steel, higher grade steel, aluminum alloy or titanium alloy and other metals, and the machining tolerance is +/-0.1 mm. The position of the through hole of the positioning block 3, through which the first locking bolt 4 penetrates, is the geometric center of the positioning block 3 in the width direction, the diameter of the through hole is one fourth to one half of the width of the positioning block 3, the machining tolerance is +/-0.1 mm, the machining tolerance of the through hole and the rectangular blind hole formed in the first rectangular-section metal rod 1 is +/-0.1 mm, and the size of the blind hole of the first rectangular-section metal rod 1 is 0.1-0.2mm larger than that of the lug seat of the positioning block 3. The cross section geometric shape of the positioning block 3 can be determined according to the structural design requirements of the composite material, simple geometric shapes such as rectangle, trapezoid and triangle can be selected, and other shapes can also be selected according to the requirements.

The processing tolerance of the lug seat of the positioning block 3 and the rectangular blind hole on the side surface of the first rectangular-section metal rod 1 matched with the lug seat is +/-0.1 mm, and the size of the rectangular blind hole on the side surface of the first rectangular-section metal rod 1 is 0.1-0.2mm larger than that of the lug seat of the positioning block 3.

The first locking bolt 4 and the second locking bolt 5 are standard parts or non-standard parts, have the specification of M6-M12, are made of high-strength metals such as 40# chromium steel, 42# chromium manganese steel, 12.9-grade high-strength steel or titanium alloy and can also be made of low-strength steel such as 45# steel, and need to be annealed.

The upper panel 7 and the lower panel 10 are fiber fabrics such as glass fiber, carbon/glass hybrid fiber, quartz fiber, Kevler fiber, ultra-high molecular weight polyethylene fiber or PBO fiber, and the surface density is more than or equal to 100g/m 2.

The dry fiber fabric 9 for the grid is a fiber fabric such as glass fiber, carbon/glass hybrid fiber, quartz fiber, Kevler fiber, ultra-high molecular weight polyethylene fiber or PB0 fiber, and the surface density is more than or equal to 100g/m 2.

It should be noted here that the dry fiber fabric 9 for the grid (i.e. the composite grid structure after resin infiltration molding) may be the same as or different from the fiber fabrics for the upper and lower panels.

The foam core material strip 8 is made of foaming materials such as polyvinyl chloride (PVC), Polymethacrylimide (PMI), polyethylene terephthalate (PET) or Polyurethane (PU) and the like, the density is less than or equal to 400kg/m3, the cross-sectional geometrical shapes of the two end parts of the foam core material strip 8 are the same as the shape and the size of the positioning block 3, the cross-sectional geometrical shapes can be determined according to the structural design requirements of the composite material, and simple geometrical shapes such as rectangle, trapezoid and triangle can be selected, and other shapes can also be selected. The integrated integral forming process has no difference with the conventional VARI forming process, the process technology is mature and stable, the process flow is simple, the product can be obtained by one-step forming, and the preparation efficiency, the appearance quality and the quality consistency are obviously improved.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.