Aramid fiber half-wrapped mobile phone shell and preparation method thereof

Abstract

The invention discloses an aramid fiber half-wrapped mobile phone shell and a preparation method, and relates to the technical field of mobile phone shells, the method comprises the following steps: S1, first deep drawing preparation; s2, drawing for the first time; s3, performing deep drawing preparation for the second time; s4, drawing for the second time; s5, mold covering; during deep drawing, materials can be tensioned through the material pressing mechanism, and therefore it is effectively guaranteed that the edges do not wrinkle when the aramid fiber half-wrapped mobile phone shell is prepared; in the deep drawing process, a material impregnated with thermoplastic resin is heated through the heating mechanism, so that the hardening effect of the thermoplastic resin on the material is weakened, and the material has good ductility; in combination with the extensibility improved by heating of the heating mechanism, the redundant waste material area and the new transition area are pre-tightened again through multi-time drawing when new drawing is carried out, and the situation that the aramid fiber protection layer with the large drawing height is pulled broken or pulled through when prepared can be effectively avoided.

Description

Technical Field

[0001] The invention relates to the technical field of mobile phone cases, and in particular to an aramid fiber half-wrapped mobile phone case and a preparation method thereof. Background Art

[0002] There are two main ways to prepare the current aramid fiber half-wrapped mobile phone case (the commonly used aramid fiber is Kevlar). The first is to firstly obtain a TPU shock-absorbing case by injection molding, and then affix aramid fiber sheets to the outside of the TPU shock-absorbing case. The second is to firstly prepare an aramid fiber shell with a frame and a bottom plate, and then cover a layer of TPU shock-absorbing shell on the aramid fiber outer layer to obtain an aramid fiber half-wrapped mobile phone case. The TPU shock-absorbing shell also has a frame and a bottom plate, and most of the frame and bottom plate of the TPU shock-absorbing shell are located on the inner side of the aramid fiber shell for contact with the installed mobile phone.

[0003] At present, when the second preparation method is used, a drawing die is mainly used to draw the aramid fiber sheet to obtain an aramid fiber shell, but its disadvantages are also obvious: when a frame with a large height needs to be drawn (aramid fiber shell), the aramid fiber sheet is easily torn or pierced, and the edges are easily wrinkled. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings, the present invention aims to provide a technical solution that can solve the above-mentioned problems.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing a semi-wrapped mobile phone case made of aramid fiber, the method comprising the following steps: S1. Preparation for the first drawing Positioning an aramid fiber sheet impregnated with a thermoplastic resin on a concave die of a first drawing die having a first drawing height, and forming the aramid fiber sheet with a back plate area corresponding to the drawing groove of the concave die of the first drawing die, a redundant waste area located at the periphery of the aramid fiber sheet, and a first transition area between the back plate area and the redundant waste area; S2, first deep drawing The first transition area and / or the redundant waste area are pre-tightened by the pressing mechanism of the first drawing die; then the aramid fiber sheet is drawn by pressing the punch of the first drawing die and the drawing groove of the concave die; during the drawing process, the pressing mechanism pre-tightens the aramid fiber sheet so that part of the first transition area can be pressed by the pressing head to enter the drawing groove; before and / or during the drawing, the aramid fiber sheet is heated by the heating mechanism of the first drawing die; After the deep drawing is completed, the aramid fiber protective layer preform is cooled and formed to obtain a preform of an aramid fiber protective layer with a first deep drawing height; the preform of the aramid fiber protective layer comprises a back plate area, a first deep drawing area continuous with the periphery of the back plate area, a redundant waste area located at the periphery of the aramid fiber protective layer preform, and a second transition area located between the first deep drawing area and the redundant waste area; S3, preparation for the second deep drawing Positioning the aramid fiber protective layer preform on a concave die of a second drawing die having a second drawing height, and positioning the back plate area and the first drawing area of ​​the aramid fiber protective layer preform in the drawing groove of the concave die of the second drawing die; S4, second deep drawing The second transition area and / or the redundant waste area are pre-tightened by the pressing mechanism of the second drawing die; then the aramid fiber protective layer preform is drawn by pressing the punch of the punch of the second drawing die and the drawing groove of the concave die; during the drawing process, the pre-tightening of the aramid fiber protective layer preform by the pressing mechanism is configured so that part of the second transition area can be pressed by the pressing head to enter the drawing groove; wherein, before and / or during the drawing, the aramid fiber protective layer preform is heated by the heating mechanism of the second drawing die; After the deep drawing is completed, the aramid fiber protective layer is cooled and formed, and cut to obtain a second deep drawing height; the aramid fiber protective layer comprises a back plate area and a second deep drawing area continuous with the periphery of the back plate area; wherein the second drawing height is greater than the first drawing height; S5, beer set The aramid fiber protective layer is placed in an injection mold to be covered with a thermoplastic shock absorbing layer; The mobile phone case is cooled and formed to obtain a half-wrapped aramid fiber case.

[0006] As a further solution of the present invention: the pressing mechanism used in step S2 and / or step S4 includes a plurality of tensioning columns installed on the die; a plurality of tensioning holes cooperating with the tensioning columns are arranged along the circumferential direction of the redundant waste area; when deep drawing is performed, the tensioning columns are passed through the tensioning holes to form tension on the aramid fiber sheet material and / or the aramid fiber protective layer preform; when deep drawing is continued, the tensioning columns form a portion on the redundant waste area from the tensioning holes to the edge of the redundant waste area to tighten.

[0007] As a further solution of the present invention: the pressing mechanism used in step S2 and / or step S4 includes a transition zone pressure plate installed on the punch along the drawing direction of the punch; a plurality of pressing guide holes are arranged on the punch, and a pressing guide column cooperating with the pressing guide holes is arranged on the transition zone pressure plate; a pressing pre-tensioning spring is sleeved on the pressing guide column, and the pressing pre-tensioning spring is constructed to be located between the transition zone pressure plate and the punch.

[0008] As a further solution of the present invention: the heating mechanism used in step S2 and / or step S4 includes a transition zone heating element which is arranged on the transition zone pressing plate and corresponds to the pressing surface of the transition zone pressing plate.

[0009] As a further solution of the present invention: the heating mechanism used in step S2 and / or step S4 includes a heating component arranged on the pressing head; the heating component has a frame heating element corresponding to the drawing side surface of the pressing head.

[0010] As a further solution of the present invention: the heating mechanism used in step S2, its heating component also has a back plate heating element corresponding to the drawing top surface of the pressing head.

[0011] As a further solution of the present invention: when both the frame heating element and the transition zone heating element are provided, the heating temperature of the transition zone heating element is lower than the heating temperature of the frame heating element.

[0012] As a further solution of the present invention: the ratio of the height of the first drawing zone of the aramid fiber protective layer to the height of the second drawing zone of the aramid fiber protective layer preform is 0.4-0.6:1.

[0013] The present invention provides the following technical solution: an aramid fiber half-wrapped mobile phone case, which is prepared by the above-mentioned preparation method; wherein the aramid fiber half-wrapped mobile phone case has a thermoplastic shock-absorbing layer in contact with the installed mobile phone, and an aramid fiber protective layer located on the outside of the thermoplastic shock-absorbing layer, and the aramid fiber is impregnated with a thermoplastic resin.

[0014] As a further solution of the present invention: the thermoplastic shock-absorbing layer is combined with the aramid fiber protective layer to form the bottom plate and frame of the aramid fiber half-wrapped mobile phone case, and the frame has an extended height direction corresponding to the side thickness of the installed mobile phone; the extended height of the aramid fiber protective layer on the frame is more than 1 / 2 of the extended height of the frame.

[0015] Compared with the prior art, the beneficial effects of the present technical solution are as follows: during deep drawing, the aramid fiber sheet and the aramid fiber protective layer prefabricated material can be tensioned by the pressing mechanism, especially the part on the transition zone that is used to be drawn to form a new drawing zone, thereby effectively ensuring that there is no wrinkling on the edge when the aramid fiber half-wrapped mobile phone case is prepared; during deep drawing, the aramid fiber sheet impregnated with thermoplastic resin and the aramid fiber protective layer prefabricated material impregnated with thermoplastic resin are heated by the heating mechanism, so that the hardening effect of the thermoplastic resin thereon becomes weak, thereby making the aramid fiber sheet or the aramid fiber protective layer prefabricated material have better ductility.

[0016] When preparing the aramid fiber protective layer, the ductility of the material is improved by heating the material with the above-mentioned heating mechanism, and multiple deep drawing is performed, each time only a part of the total drawing height is drawn. After cooling and forming, the next deep drawing is performed. When the new deep drawing is performed, the redundant waste area and the new transition area are pre-tightened again, which can effectively avoid the situation of tearing or pulling through when preparing the aramid fiber protective layer with a large drawing height.

[0017] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0019] Figure 1 This is a structural stereogram of the aramid fiber half-wrapped mobile phone case of the present invention; Figure 2 This is an exploded view of the structure of the aramid fiber half-wrapped mobile phone case of the present invention; Figure 3 is a flow chart of the preparation method of the present invention; Figure 4 It is a schematic diagram of the secondary drawing process in the preparation method of the present invention; Figure 5 It is a schematic structural diagram of the aramid fiber sheet material used in the preparation method of the present invention; Figure 6 It is a schematic structural diagram of the aramid fiber protective layer prefabricated material used in the preparation method of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] See also Figure 1-2In this embodiment, an aramid fiber half-wrapped mobile phone case 100 has a thermoplastic shock absorbing layer 8 in contact with the installed mobile phone, and an aramid fiber protective layer 7 located outside the thermoplastic shock absorbing layer 8, and the aramid fiber of the aramid fiber protective layer 7 is impregnated with a thermoplastic resin. The impregnated thermoplastic resin is, for example, polyethylene resin, modified polyethylene resin, etc.

[0022] The thermoplastic shock absorbing layer 8 is combined with the aramid fiber protective layer 7 to form the bottom plate 200 and the frame 300 of the aramid fiber half-wrapped mobile phone case 100, that is, the aramid fiber half-wrapped mobile phone case 100 actually has a mobile phone installation groove formed by the bottom plate 200 and the frame 300.

[0023] Preferably, the frame 300 has an extension height direction corresponding to the thickness of the side of the installed mobile phone; the extension height of the aramid fiber protective layer 7 on the frame is more than 1 / 2 of the extension height of the frame 300.

[0024] In this embodiment, the thermoplastic shock absorbing layer 8 is prepared on the aramid fiber protective layer 7 impregnated with thermoplastic resin by using a beer coating method. During the beer coating, the molten thermoplastic material is fully in contact with the thermoplastic resin on the aramid fiber protective layer 7. After cooling and forming, the thermoplastic resin makes the thermoplastic shock absorbing layer 8 and the aramid fiber protective layer 7 have good adhesion. In daily use of the aramid fiber half-wrapped mobile phone case 100, the aramid fiber protective layer 7 and the thermoplastic shock absorbing layer 8 are less likely to separate.

[0025] The thermoplastic shock-absorbing layer 8 is made of, for example, TPU material, PU material, etc.

[0026] See also Figure 1-6 In this embodiment, the aramid fiber half-wrapped mobile phone shell 100 is prepared by the following preparation method, which includes the following steps: S1. Preparation for the first drawing The aramid fiber sheet 1 impregnated with thermoplastic resin is positioned and placed on the concave die 2 of the first drawing die with a first drawing height, and the aramid fiber sheet 1 is formed with a back plate area 101 corresponding to the drawing groove 201 of the concave die of the first drawing die, a redundant waste area 102 located at the periphery of the aramid fiber sheet 1, and a first transition area 103 located between the back plate area 101 and the redundant waste area 102; S2, first deep drawing The first transition area 103 and / or the redundant waste area 102 are pre-tightened by the pressing mechanism of the first drawing die; then the punch 3 of the punch of the first drawing die is pressed into contact with the drawing groove 201 of the concave die to draw the aramid fiber sheet 1; during the drawing process, the pre-tightening of the aramid fiber sheet 1 by the pressing mechanism is configured so that part of the first transition area 103 can be pressed by the punch 3 to enter the drawing groove 201; wherein, before and / or during the drawing, the aramid fiber sheet 1 is heated by the heating mechanism of the first drawing die; After the deep drawing is completed, the aramid fiber protective layer preform 4 is cooled and formed to obtain a first deep drawing height; the aramid fiber protective layer preform 4 comprises a back plate area 401, a first deep drawing area 402 continuous with the periphery of the back plate area 401, a redundant waste area 403 located at the periphery of the aramid fiber protective layer preform 4, and a second transition area 404 located between the first deep drawing area 402 and the redundant waste area 403; S3, preparation for the second deep drawing Positioning the aramid fiber protective layer preform 4 on the concave die 5 of the second drawing die with a second drawing height, and making the back plate area 401 and the first drawing area 402 of the aramid fiber protective layer preform 4 located in the drawing groove 501 of the concave die of the second drawing die; S4, second deep drawing The second transition area 404 and / or the redundant waste area 403 are pre-tightened by the pressing mechanism of the second drawing die; then the punch 6 of the second drawing die is pressed into contact with the drawing groove 501 of the concave die to draw the aramid fiber protective layer preform 4; during the drawing process, the pressing mechanism pre-tightens the aramid fiber protective layer preform 4 so that part of the second transition area 404 can be pressed by the punch 6 to enter the drawing groove 501; wherein, before and / or during the drawing, the aramid fiber protective layer preform 4 is heated by the heating mechanism of the second drawing die; After the deep drawing is completed, the aramid fiber protective layer 7 with a second deep drawing height is obtained by cooling and forming, and cutting; the aramid fiber protective layer 7 has a back plate area 701 and a second deep drawing area 702 continuous with the periphery of the back plate area 701; wherein the second drawing height is greater than the first drawing height; S5, beer set The aramid fiber protective layer 7 is placed in an injection mold to be covered with a thermoplastic shock absorbing layer 8; The aramid fiber half-wrapped mobile phone case 100 is obtained by cooling and forming.

[0027] In step S4 , the cutting is to cut at least the portion other than the back plate area 701 and the second drawing area 702 , such as cutting the redundant waste area 403 and the portion of the original second transition area 404 close to the redundant waste area 403 .

[0028] The second drawing height is greater than the first drawing height, that is, the height (in the drawing direction) of the second drawing zone 702 is greater than the height (in the drawing direction) of the first drawing zone 402 .

[0029] During the deep drawing, the aramid fiber sheet 1 and the aramid fiber protective layer preform 4 can be tensioned by the pressing mechanism, especially the portion on the transition zone (first transition zone 103, second transition zone 404) that is used to be drawn to form a new drawing zone (first drawing zone 402, second drawing zone 702), thereby effectively ensuring that the edges are free of wrinkles when the aramid fiber half-wrapped mobile phone case 100 is prepared.

[0030] During deep drawing, the aramid fiber sheet 1 impregnated with thermoplastic resin and the aramid fiber protective layer preform 4 impregnated with thermoplastic resin are heated by a heating mechanism, so that the hardening effect of the thermoplastic resin thereon is weakened, thereby making the aramid fiber sheet 1 or the aramid fiber protective layer preform 4 have better ductility. When preparing the aramid fiber protective layer, the ductility of the material is improved by heating the heating mechanism, and multiple deep drawing is performed, each time only a part of the total drawing height is drawn, and after cooling and forming, the next deep drawing is performed, and when the new deep drawing is performed, the redundant waste area and the new transition area are pre-tightened again, which can effectively avoid the situation of tearing or pulling through when preparing the aramid fiber protective layer with a large drawing height.

[0031] In some embodiments, the pressing mechanism used in step S2 and / or step S4 includes a plurality of tensioning posts 9 mounted on the concave mold (2, 5). A plurality of tensioning holes cooperating with the tensioning posts 9 are arranged along the circumferential direction on the redundant waste area (102, 403); when deep drawing is performed, the tensioning posts 9 are penetrated through the tensioning holes to form the aramid fiber sheet 1 and / or the aramid fiber protective layer preform 4 for tensioning.

[0032] During continuous drawing, the tensioning column 9 continuously tensions the aramid fiber sheet 1 and / or the aramid fiber protective layer preform 4, and tears the portion from the tensioning hole to the edge of the redundant waste area (102, 403). On the one hand, the tensioning column can make the aramid fiber sheet 1 and / or the aramid fiber protective layer preform 4 better aligned and positioned through the tensioning holes thereon during the preparation for deep drawing, and on the other hand, during deep drawing, the aramid fiber sheet 1 and / or the aramid fiber protective layer preform 4 can be tensioned, which has better functionality.

[0033] Preferably, when drawn into place, the tensioning column 9 is configured to tear off the portion of the redundant waste area (102, 403) from the tensioning hole to the edge of the redundant waste area.

[0034] In some embodiments, the pressing mechanism used in step S2 and step S4 includes a plurality of tensioning posts 9 installed on the female die. That is, the pressing mechanism on the first drawing die includes a plurality of tensioning posts installed on the female die 2 of the first drawing die; the pressing mechanism on the second drawing die includes a plurality of tensioning posts installed on the female die 5 of the second drawing die.

[0035] In some embodiments, before performing step S1, a plurality of tensioning holes are opened in the aramid fiber sheet 1, and the plurality of tensioning holes are formed into two parts. The tensioning holes in the first part are used to cooperate with the tensioning columns of the first drawing die for the first drawing during the first drawing; and the tensioning holes in the second part are used to cooperate with the tensioning columns of the second drawing die for the second drawing during the second drawing.

[0036] If the aramid fiber sheet 1 is an aramid fiber fabric, when the aramid fiber sheet 1 is finally prepared to form the outer protective layer of the aramid fiber half-wrapped mobile phone case 100, the texture of the aramid fiber fabric can also be used as the appearance of the aramid fiber half-wrapped mobile phone case 100. Taking the aramid fiber fabric woven with warp and weft as an example, the ductility of the aramid fiber fabric mainly comes from the gap between the warp and the weft, the gap between the warp and the warp, the gap between the weft and the weft, the tension of the warp when weaving, and the tension of the weft when weaving; during deep drawing, the thermoplastic resin impregnated is heated to reduce the hardening effect of the thermoplastic resin on the aramid fiber sheet 1 and the aramid fiber protective layer preform 4, so that the various factors that determine the ductility of the aramid fiber fabric can be better utilized, so that the aramid fiber sheet 1 or the aramid fiber protective layer preform has better ductility during deep drawing.

[0037] In some embodiments, the pressing mechanism used in step S2 and / or step S4 includes a transition zone pressing plate 10 installed on the punch along the drawing direction of the punch.

[0038] A plurality of pressure guide holes are arranged on the punch (the punch of the first drawing die and the punch of the second drawing die), and a pressure guide column 11 cooperating with the pressure guide holes is arranged on the transition zone pressure plate 10; a pressure pre-tensioning spring 12 is sleeved on the pressure guide column 11, and the pressure pre-tensioning spring 12 is constructed to be located between the transition zone pressure plate 10 and the punch.

[0039] During deep drawing, the transition zone is firstly pressed by the transition zone pressure plate 10 to effectively avoid displacement of the aramid fiber sheet 1 and / or the aramid fiber protective layer preform 4; during deep drawing, by the elastic performance of the material preload spring 12 and the strength of the aramid fiber, when the pressure applied by the pressing head (3, 6) to the material is relatively large, the material on the transition zone can overcome the pressure applied by the material preload spring 12 through the transition zone pressure plate 10, thereby converging and approaching the pressing head or the drawing groove, thereby making better use of the ductility of the material, especially the ductility of the transition zone and the redundant waste area close to the transition zone, effectively avoiding tearing or penetration during deep drawing.

[0040] Furthermore, the heating mechanism used in step S2 and / or step S4 includes a transition zone heating element 13 which is arranged on the transition zone pressing plate 10 and corresponds to the pressing surface of the transition zone pressing plate 10 .

[0041] In some embodiments, the heating mechanism used in step S2 and / or step S4 includes a heating component arranged on the pressing head (3, 6); the heating component has a frame heating element 15 corresponding to the drawing side surface of the pressing head (3, 6).

[0042] In some embodiments, when the heating mechanism used in step S2 and / or step S4 includes both the frame heating element 15 and the transition zone heating element 13 , the heating temperature of the transition zone heating element 13 is lower than the heating temperature of the frame heating element 15 .

[0043] In some embodiments, the pressing mechanism includes both the transition zone pressing plate 10 of any of the above embodiments and the tensioning column 9 of any of the above embodiments.

[0044] In some embodiments, the pressing mechanism includes a tensioning column 9 and a transition zone pressing plate 10 at the same time, the heating mechanism of the first drawing die includes a transition zone heating element, a back plate heating element 14 and a frame heating element at the same time, and the heating mechanism of the second drawing die includes a transition zone heating element and a frame heating element at the same time, wherein the heating temperature of the transition zone heating element is lower than the heating temperature of the frame heating element.

[0045] The transition zone is configured to form regional temperature isolation between the redundant waste zone and the back plate zone. More specifically, the first transition zone 103 of the aramid fiber sheet is configured to form regional temperature isolation between the redundant waste zone 102 of the aramid fiber sheet and the back plate zone 101 of the aramid fiber sheet (and the portion of the first transition zone 103 close to the back plate zone 101) of the aramid fiber sheet; the second transition zone 404 of the aramid fiber protective layer preform is configured to form regional temperature isolation between the redundant waste zone 403 of the aramid fiber protective layer preform and the first deep drawing zone 402 on the back plate zone 401 of the aramid fiber protective layer preform (and the portion of the second transition zone 404 close to the back plate zone 401) of the aramid fiber protective layer preform.

[0046] After the material is pre-tightened by the pressing mechanism and before or during deep drawing, the transition zone heating element 13 presses the transition zone with the help of the transition zone pressing plate 10, so as to preheat the transition zone to the first temperature range; then during deep drawing, the pressing head presses the back panel area and the contact is generated by drawing the portion of the transition zone close to the back panel area, so that the frame heating element continues to heat the portion of the transition zone that is constantly approaching the pressing head (constantly approaching the drawing groove) to the second temperature range.

[0047] The temperature value of the second temperature range is greater than the temperature value of the first temperature range.

[0048] In some embodiments, the second temperature range corresponds to a softened state of the impregnated thermoplastic resin. By heating the thermoplastic resin to a softened state, it has better drawing properties; when drawing, the portion of the transition zone close to the pressure head has better ductility; and by setting the heating temperature before the melting temperature, it is possible to avoid serious overflow of the molten resin when the aramid fiber is drawn.

[0049] In some embodiments, the heating mechanism used in step S2 has a heating component that further includes a back plate heating element 14 corresponding to the top surface of the pressing head 3 .

[0050] During the first deep drawing, the back plate area is heated by the back plate heater 14 , so that the ductility of the back plate area can also be utilized for the overall deep drawing.

[0051] In some embodiments, the heating mechanism used in step S4 has a heating component that further includes a back plate heating element 14 corresponding to the top surface of the pressing head 3 .

[0052] Preferably, after deep drawing is completed, the back panel heating element 14 and the frame heating element 15 are controlled to heat the back panel area (401, 701) and the deep drawing area (the first deep drawing area 402, the second deep drawing area 702) to make the impregnated resin in a molten state. This allows the thermoplastic resin to flow into the deep drawing area and the back panel area again after the deep drawing of the aramid fiber sheet and the aramid fiber protective layer preform, so that the thickness of the thermoplastic resin re-impregnated in the deep drawing area and the back panel area tends to be the same, effectively ensuring that the hardness of the deep drawing area and the back panel area tends to be uniform and the hand feeling area is uniform after molding.

[0053] In some embodiments, the back plate heating element 14 of the heating mechanism used in step S4 does not heat the back plate area 401 during deep drawing, and is controlled to heat only after deep drawing is in place; and during the first deep drawing, the back plate area 101 is heated by the back plate heating element 14 of the heating mechanism of the first drawing die. During the first deep drawing, the ductility of the back plate area 101 is fully utilized; during the subsequent second deep drawing, since the back plate area has been deep drawn, by avoiding overheating of the back plate area 401 during the second deep drawing, it is ensured that the thermoplastic resin on the back plate area 401 can better increase its strength, so that under the same deep drawing conditions, the ductility of the undrawn part of the transition zone can be preferentially expanded, effectively avoiding the back plate area from being torn or pulled through during the second deep drawing.

[0054] It is worth noting that the pressing and drawing speed of the pressing head (3, 6) and the drawing groove (201, 501) is as close as possible to the transition zone being preheated to the minimum value of the first temperature range by the transition zone heating element 13, and the portion of the transition zone close to the back panel area (the portion that has not entered the drawing groove) being heated to the minimum value of the second temperature range by the frame heating element.

[0055] In some embodiments, the ratio of the height of the first drawing area of ​​the aramid fiber protective layer to the height of the second drawing area of ​​the aramid fiber protective layer preform is 0.4-0.6:1, such as 0.4:1, 0.5:1, 0.6:1, etc. That is, during the first drawing, only 40%-60% of the extended height of the aramid fiber protective layer is drawn; during the second drawing, the remaining portion is continued to be drawn.

[0056] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing an aramid fiber half-wrapped mobile phone case, characterized in that: The method comprises the following steps S1. Preparation for the first drawing Positioning an aramid fiber sheet impregnated with a thermoplastic resin on a concave die of a first drawing die having a first drawing height, and forming the aramid fiber sheet with a back plate area corresponding to the drawing groove of the concave die of the first drawing die, a redundant waste area located at the periphery of the aramid fiber sheet, and a first transition area between the back plate area and the redundant waste area; S2, first deep drawing The first transition area and / or the redundant waste area are pre-tightened by the pressing mechanism of the first drawing die; then the aramid fiber sheet is drawn by pressing the punch of the first drawing die and the drawing groove of the concave die; during the drawing process, the pressing mechanism pre-tightens the aramid fiber sheet so that part of the first transition area can be pressed by the pressing head to enter the drawing groove; before and / or during the drawing, the aramid fiber sheet is heated by the heating mechanism of the first drawing die; After the deep drawing is completed, the aramid fiber protective layer preform is cooled and formed to obtain a preform of an aramid fiber protective layer with a first deep drawing height; the preform of the aramid fiber protective layer comprises a back plate area, a first deep drawing area continuous with the periphery of the back plate area, a redundant waste area located at the periphery of the aramid fiber protective layer preform, and a second transition area located between the first deep drawing area and the redundant waste area; S3, preparation for the second deep drawing Positioning the aramid fiber protective layer preform on a concave die of a second drawing die having a second drawing height, and positioning the back plate area and the first drawing area of ​​the aramid fiber protective layer preform in the drawing groove of the concave die of the second drawing die; S4, second deep drawing The second transition area and / or the redundant waste area are pre-tightened by the pressing mechanism of the second drawing die; then the aramid fiber protective layer preform is drawn by pressing the punch of the punch of the second drawing die and the drawing groove of the concave die; during the drawing process, the pre-tightening of the aramid fiber protective layer preform by the pressing mechanism is configured so that part of the second transition area can be pressed by the pressing head to enter the drawing groove; wherein, before and / or during the drawing, the aramid fiber protective layer preform is heated by the heating mechanism of the second drawing die; After the deep drawing is completed, the aramid fiber protective layer is cooled and formed, and cut to obtain a second deep drawing height; the aramid fiber protective layer comprises a back plate area and a second deep drawing area continuous with the periphery of the back plate area; wherein the second drawing height is greater than the first drawing height; S5, beer set The aramid fiber protective layer is placed in an injection mold to be covered with a thermoplastic shock absorbing layer; The mobile phone case is half-wrapped with aramid fibers and then cooled and formed.

2. The preparation method according to claim 1, characterized in that: The pressing mechanism used in step S2 and / or step S4 includes a plurality of tensioning columns installed on the die; A plurality of tensioning holes cooperating with the tensioning posts are arranged along the circumferential direction of the redundant waste area; during deep drawing, the tensioning posts are penetrated through the tensioning holes to form the aramid fiber sheet material and / or the aramid fiber protective layer preform to be tensioned; During continuous drawing, the tensioning column is formed to tighten the portion of the redundant waste area from the tensioning hole to the edge of the redundant waste area.

3. The preparation method according to claim 1 or 2, characterized in that: The material pressing mechanism used in step S2 and / or step S4 includes a transition zone pressing plate installed on the punch along the drawing direction of the punch; The punch is provided with a plurality of press guide holes, and the transition zone pressure plate is provided with press guide posts that match the press guide holes; the press guide posts are sleeved with press preload springs, and the press preload springs are constructed to be located between the transition zone pressure plate and the punch.

4. The preparation method according to claim 3, characterized in that: The heating mechanism used in step S2 and / or step S4 includes a transition zone heating element which is arranged on the transition zone pressing plate and corresponds to the material pressing surface of the transition zone pressing plate.

5. The preparation method according to claim 1, 2 or 4, characterized in that: The heating mechanism used in step S2 and / or step S4 includes a heating assembly disposed on the pressure head; The heating assembly has a frame heating element corresponding to the drawing side surface of the pressing head.

6. The preparation method according to claim 5, characterized in that: The heating mechanism used in step S2, its heating assembly also has a back plate heating element corresponding to the drawing top surface of the pressing head.

7. The preparation method according to claim 5, characterized in that: When both the frame heating element and the transition zone heating element are provided, the heating temperature of the transition zone heating element is lower than the heating temperature of the frame heating element.

8. The preparation method according to claim 1 or 2 or 4 or 6 or 7, characterized in that: The ratio of the height of the first drawing area of ​​the aramid fiber protective layer to the height of the second drawing area of ​​the aramid fiber protective layer preform is 0.4-0.6:

1.

9. An aramid fiber half-wrapped mobile phone case, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8; The aramid fiber half-wrapped mobile phone case comprises a thermoplastic shock-absorbing layer in contact with the installed mobile phone, and an aramid fiber protective layer located outside the thermoplastic shock-absorbing layer, wherein the aramid fiber is impregnated with a thermoplastic resin.

10. The aramid fiber half-wrapped mobile phone case according to claim 9, characterized in that: The thermoplastic shock-absorbing layer is combined with the aramid fiber protective layer to form a bottom plate and a frame of the aramid fiber half-wrapped mobile phone case, and the frame has an extended height direction corresponding to the thickness of the side of the installed mobile phone; The extending height of the aramid fiber protective layer on the frame is more than 1 / 2 of the extending height of the frame.

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