A processing mold and molding device for wheel rim film and wheel rim film

Abstract

The invention discloses a processing mold and a molding device for a wheel rim film and a wheel rim film, belonging to the field of plastic processing and molding, including a matching lower mold and an upper mold, wherein the lower mold and the upper mold are both provided with a heating structure, a plurality of lower mold cores protruding upward are provided on the top surface of the lower mold; a plurality of upper mold cores protruding downward are provided on the bottom surface of the upper mold; a plurality of elastic demoulding structures are installed on the lower mold and the upper mold, and the elastic demoulding structures are evenly distributed between two adjacent lower mold cores and between two adjacent upper mold cores. The invention can demould quickly and prevent the film from being adhered to the upper and lower molds.

Description

Technical Field

[0001] The invention belongs to the field of plastic processing and molding, and relates to a processing mold and a molding device for a wheel rim film and the wheel rim film. Background Art

[0002] The air bag forming process is a common process for preparing bicycle rims. For example, patent 201010594034.X discloses a method for manufacturing bicycle rims and CN201410014992.3 discloses a process for producing carbon fiber composite material rims. The air bag can directly or indirectly contact the rim material; the rim film forms the air bag in the air bag forming process.

[0003] In order to optimize the contact surface between the air bag and its contact parts, reduce adhesion and friction, and make it easier to separate the air bag from the contact parts after the bicycle rim is formed, the rim film is currently hot-pressed and a mold is used to form evenly and continuously distributed patterns on the rim film. The patterns form tiny raised and depressed structures, which make the contact between the air bag and its contact parts discontinuous, thereby reducing the actual contact points, which in turn facilitates demolding between the air bag and its contact parts.

[0004] At present, when the wheel rim film is hot-pressed, it is easy for the wheel rim film to be incompletely demolded during demolding. The wheel rim film will partially stick to the upper mold or the lower mold. The wheel rim film adhered to the upper mold or the lower mold will be overheated. After being overheated, it will be over-softened. Under the action of external force, the over-softened part will be unevenly stressed and easily damaged during the demolding process. In addition, the mechanical strength of this part of the wheel rim film will be weaker than other parts, affecting the manufacture of bicycle rims. Summary of the invention

[0005] The purpose of the present invention is to provide a processing mold and a molding device for a rim film and a rim film, which solves the problem that when the rim film is currently hot-pressed, the rim film is easily not completely demolded, and the rim film partially sticks to the upper mold or the lower mold, thereby reducing the quality of the rim film.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A processing mold for a wheel rim film comprises a matching lower mold and an upper mold, wherein heating structures are arranged inside the lower mold and the upper mold, a plurality of lower mold cores protruding upward are arranged on the top surface of the lower mold, all the lower mold cores are arranged one by one and evenly along the long side direction of the lower mold, and a cavity is formed between two adjacent lower mold cores; a plurality of upper mold cores protruding downward are arranged on the bottom surface of the upper mold, all the upper mold cores are arranged one by one along the long side direction of the upper mold, and the upper mold cores are arranged alternately with the lower mold cores, the upper mold cores correspond to the cavities on the lower mold one by one, and the shapes of the cavities on the upper mold cores and the lower mold cores match;

[0008] A plurality of elastic demoulding structures are installed on the lower mold and the upper mold, and the elastic demoulding structures are evenly distributed between two adjacent lower mold cores and between two adjacent upper mold cores;

[0009] The elastic demoulding structure comprises a cylinder with an opening at one end, a spring column is installed inside the cylinder, the spring column is retracted in the axial direction of the cylinder, one end of the spring column is connected and fixed to the sealing end of the cylinder, and an ejector is installed on the other end of the spring column, the long side of the ejector is parallel to the central axis of the cylinder, the tail of the ejector is connected and fixed to the spring column, and the front end surface of the ejector is arc-shaped; a plug for blocking the opening is detachably connected to the open end of the cylinder, the outer end surface of the plug is flush with the open end surface of the cylinder, and a small hole for the ejector to pass through is provided on the plug; a blind hole for installing the elastic demoulding structure is provided on the lower mold and the upper mold, the cylinder is tightly connected to the inner wall of the blind hole, the open end of the blind hole is an end close to the middle area of ​​the lower mold and the upper mold, the front end of the ejector faces the middle area of ​​the lower mold and the upper mold, and the end surface of the open end of the cylinder is flush with the corresponding lower mold top surface or upper mold bottom surface; when the spring column in the elastic demoulding structure is in the original state, the front end of the ejector passes through the plug and is located outside the cylinder.

[0010] Furthermore, when the spring column in the elastic demolding structure is in its original state, the front end of the ejector pin passes through the plug and is located outside the cylinder, wherein the front end of the ejector pin on the lower mold is located above the top surface of the lower mold core, and the front end of the ejector pin on the upper mold is located below the bottom surface of the upper mold core, and the distance between the front end of the ejector pin and the corresponding top surface of the lower mold core or the bottom surface of the upper mold core is 1 mm.

[0011] In the present invention, a heating structure is installed inside the upper mold and the lower mold, generally an electric heating structure is adopted, the electric heating structure heats the upper mold and the lower mold, and the heated upper mold and the lower mold are pressed together to perform hot pressing molding on the middle rim film. After hot pressing molding, the upper and lower molds are separated, and then the rim film is pulled out from between the upper mold and the lower mold by the rim film traction equipment, and embossing is formed on the surface of the rim film. After the rim film is cooled, the hot pressing molding of the rim film is completed.

[0012] The present invention is based on the upper and lower molds prepared from the existing heat-conducting metal, and an elastic demolding structure is installed on both the upper and lower molds. The elastic demolding structure is used to assist the demolding of the wheel rim film, and can effectively prevent the wheel rim film from sticking to the upper mold or the lower mold, solving the problem that the wheel rim film is not easily demolded thoroughly when the wheel rim film is hot-pressed and formed, and the wheel rim film is partially stuck to the upper mold or the lower mold, thereby reducing the quality of the wheel rim film. In the present invention, the mold core on the upper mold is called the upper mold core, and the mold core on the lower mold is called the lower mold core. The mold cores of the upper and lower molds are staggered to form a cavity, and the wheel rim film is located inside the cavity. After a period of pressing, an embossing is formed on the surface of the wheel rim film, and the embossing matches the shape of the cavity formed by the upper and lower mold cores.

[0013] The principle of the elastic demoulding structure in the present invention is as follows: the cylinder in the present invention is a supporting structure, and the cylinder is connected and fixed with the upper mold and the lower mold; after the cylinder is installed in the blind holes on the upper mold and the lower mold, the opening of the cylinder is connected with the opening of the blind hole, and the opening of the cylinder is toward the middle area between the upper mold and the lower mold, that is, the opening of the cylinder on the upper mold faces downward, and the opening of the cylinder on the lower mold faces upward, and the spring column inside the cylinder will be compressed toward the inside of the cylinder under the action of external pressure, and the spring column will be shortened to drive the ejector pin to move toward the inside of the cylinder; before the rim film is hot-pressed, the upper and lower molds are separated, and the spring column in the elastic demoulding structure is at its original length. At this time, the front end of the ejector pin is evenly positioned. The upper and lower molds are located outside the corresponding upper and lower molds, wherein the front end of the ejector pin on the lower mold is located above the top surface of the lower mold core, and the front end of the ejector pin on the upper mold is located below the bottom surface of the upper mold core; after the wheel rim film portion is pulled between the upper and lower molds, the wheel rim film is flattened on the lower mold core of the lower mold, and then the upper mold is pressed down by a telescopic column and other structures. After the upper mold and the lower mold are pressed together, the mold cores of the upper and lower molds are staggered to form a cavity, and the wheel rim film is located inside the cavity. The upper mold core is pressed into the cavity between the two adjacent lower mold cores below it, and the lower mold core is correspondingly pressed into the cavity between the two corresponding upper mold cores. During the downward pressing of the upper mold core, the ejector pin at the corresponding position on the lower mold will be pushed downward, and the ejector pin moves downward. During the process, the spring column connected to it will be compressed. After the spring column is shortened, the ejector pin will completely enter the cylinder without affecting the hot pressing of the wheel rim film by the upper mold core. Similarly, the lower mold core pushes the ejector pin at the corresponding position of the upper mold upward. Under the deformation of the spring column, the ejector pin will be pushed into the cylinder without affecting the hot pressing of the wheel rim film by the lower mold core. After a period of pressing, embossing is formed on the surface of the wheel rim film. Subsequently, the upper mold is pulled up by the telescopic column and other structures that control the movement of the upper mold to separate the upper mold from the lower mold. After the upper and lower molds are separated, the force exerted by the upper and lower mold cores on the ejector pins on the opposite side is cancelled. In the absence of external force, the spring column returns to its original length and the upper mold is The ejector pins on the lower die will push the rim film toward the side where the rim film is located, the ejector pins on the upper die will push the rim film downward away from the upper die, and the ejector pins on the lower die will simultaneously push the rim film upward away from the lower die. As the distance between the upper and lower dies increases, the ejector pins on the upper die will eventually detach from the rim film, and the ejector pins on both sides of the rim film will not push the rim film at the same time. At this time, the rim film will naturally fall on the core of the lower die and will not adhere to the cores on both sides. Finally, the rim film traction equipment will quickly pull the rim film out from between the upper die and the lower die, and then manually perform operations such as shearing on the rim film to complete the hot pressing and demolding of the rim film.

[0014] The present invention installs elastic demoulding structures on both the upper mold and the lower mold, and utilizes the pressing force between the upper and lower molds during the hot pressing forming process, so that the ejector pin in the elastic demoulding structure does not push the wheel rim film during the hot pressing forming of the wheel rim film, thereby avoiding affecting the forming of the wheel rim film; and utilizes the recovery deformation of the spring column, so that after the upper and lower molds are separated, the ejector pin pushes the wheel rim film in the direction where the wheel rim film is located, so that the wheel rim film does not adhere to the upper and lower molds, and is demoulded smoothly, thereby solving the problem that the wheel rim film is easily demoulded incompletely during demoulding when the wheel rim film is hot pressed, and the wheel rim film is partially adhered to the upper mold or the lower mold, thereby reducing the quality of the wheel rim film.

[0015] The top of the ejector pin in the present invention is not a pointed end but a circular arc surface, which can prevent the ejector pin from piercing the wheel rim film.

[0016] Furthermore, a plurality of elastic demolding structures are arranged in the channel formed between two adjacent lower mold cores and in the channel formed between two adjacent upper mold cores, and all elastic demolding structures located in the same channel are arranged one by one and evenly along the wide side of the corresponding lower mold or upper mold.

[0017] Multiple elastic demoulding structures in the same channel act synchronously, which has a good pushing effect on the wheel rim film.

[0018] Furthermore, the upper mold core and the lower mold core have the same mold core structure, the mold core structure is a triangular prism structure, the top surface of the mold core structure is an arc surface, the top surface of the lower mold core faces upward, and the top surface of the upper mold core faces downward;

[0019] The end face of the mold core structure is an isosceles triangle with a rounded vertex angle, the base angle β of the end face of the mold core structure is 45-50°, and the height H of the end face of the mold core structure is 4-5 mm.

[0020] The core structure of the present invention is a triangular prism structure with a rounded top. The arc surface formed on the top after rounding is used to protect the wheel rim film from being split or cut by the top of the core during hot pressing. On the other hand, it is used to form an embossing with an arc surface on the top. The arc surface has a larger contact area than the linear surface. When the wheel rim film is separated from its contact part, it can also ensure that the two can be in close contact and avoid separation before the end of hot pressing. In addition, referring to the principle of triangle stability, the core structure of the present invention with a triangular end face is stable and balanced in force.

[0021] Furthermore, the core structure comprises a solid main body structure made of aluminum, the outside of the main body structure is coated with a thermally conductive silicone layer, the outside of the thermally conductive silicone layer is coated with an aluminum layer, and the outer wall of the aluminum layer is coated with a polytetrafluoroethylene non-stick layer;

[0022] A plurality of flexible heat-conducting sheets are installed inside the core structure, and the flexible heat-conducting sheets are in contact with the main structure, the heat-conducting silicone layer, and the aluminum layer, and the flexible heat-conducting sheets are graphene heat-conducting sheets.

[0023] In the present invention, solid aluminum serves as the main structure of the mold core, which not only has good thermal conductivity, but also has a stable supporting effect; the thermally conductive silicone layer not only has a thermal conductive function, but also has a certain elasticity and buffering effect. It can play a buffering role when the mold core is subjected to external pressure or impact, and protect the main structure from damage; at the same time, the external aluminum layer also provides additional support and fixing effects, thereby enhancing the overall stability of the mold core; the polytetrafluoroethylene non-stick layer coated on the outer wall of the aluminum layer has extremely high temperature resistance and anti-stick properties, which can prevent the mold from adhering materials or residues during use; graphene has extremely high thermal conductivity, which is tens to hundreds of times that of copper, so it can quickly disperse the heat inside the main structure and conduct it to the external heat dissipation layer. At the same time, the design of the flexible thermal conductive sheet enables it to adapt to various complex shapes and gaps, ensuring effective heat transfer; in addition, the thermally conductive silicone layer can also fill uneven surface gaps to ensure the continuity of heat transfer. This multi-layer thermal conductive structure greatly improves the heat transfer efficiency.

[0024] The molding device containing the above-mentioned processing mold comprises a base, a lower mold is installed on the top surface of the base, an upper mold is located above the lower mold, the upper mold is connected and fixed to the base through a frame, and a vertically installed telescopic column is connected to the top of the upper mold, and the telescopic column is installed on the frame; a heating structure is provided inside the lower mold and the upper mold, and under the action of the telescopic column, the upper mold and the lower mold are pressed together to perform hot pressing molding on the wheel rim film between the upper mold and the lower mold; the telescopic column can be a hydraulic lifting column;

[0025] A roller and a film traction mechanism are also installed on the top surface of the base. The roller is installed on the roller frame, and the roller frame is installed on the base. The roller is rotatably connected to the roller frame. The roller and the film traction mechanism are respectively located on both sides of the lower mold. The rim film is evenly wound on the roller, and one end of the rim film passes through the area between the upper mold and the lower mold and is clamped in the film traction mechanism; the film traction mechanism pulls the rim film on the roller into the area between the upper mold and the lower mold for molding, and then pulls the molded rim film out of the area between the upper mold and the lower mold after molding.

[0026] Furthermore, the film traction mechanism includes a vertically placed support column, which is located on one side of the lower mold and has a traction distance between the support column and the lower mold. The support column is connected and fixed to the base, and a horizontally placed horizontal telescopic column is installed on the support column. The fixed end of the horizontal telescopic column is connected and fixed to the support column, and a wheel rim film clamping structure is installed on the movable end of the horizontal telescopic column; the horizontal telescopic column is telescoped along its axial direction to achieve traction of the wheel rim film.

[0027] The horizontal telescopic column in the present invention can be a hydraulic or electric telescopic column; the wheel rim film clamping structure in the present invention can adopt a rubber surface clamp or a corrugated flat jaw clamp used in a wheel rim film tensile testing machine for clamping the wheel rim film.

[0028] Furthermore, the temperature of the upper mold and the lower mold are both 85-86° C. At 85-86° C., the wheel rim film can be quickly cooled and shaped under the cooling of a fan or blower after hot pressing, without the need for a complex and time-consuming cooling process; in the actual production process, it is necessary to use a wheel rim film that can be deformed at 85-86° C., and the wheel rim film will not be softened and produce fluidity at this temperature.

[0029] A wheel rim film is a film with continuous folds, the top surface of the folds is an arc surface, the side surface of the folds is a rectangular surface, the end surface of the folds is an isosceles triangle, and the base angle α of the isosceles triangle is 45-50 degrees.

[0030] In the actual processing, the wheel rim film formed by the up-blowing or down-blowing process is a double-layer film structure. After the two ends of the double-layer film are sealed and an inflation port is opened, an air bag can be formed. Before inflation, the top surface of the wheel rim film is an arc, the two side surfaces are rectangular surfaces, and the two end surfaces are isosceles triangles with rounded tops. Multiple continuously arranged folds form an undulating pattern. The air bag formed after inflation is easy to remove as a whole after the wheel rim is formed, and no wheel rim film remains. Moreover, under the above-mentioned fold structure, the air bag structure formed is stable, and there is no deformation caused by uneven force during the wheel rim forming process after inflation.

[0031] Furthermore, the wheel rim film comprises low-density polyethylene and polypropylene in a mass ratio of 3:2. The wheel rim film prepared under this formula can be deformed by compression at 85-86°C, and the wheel rim film will not be softened and produce fluidity at this temperature; and the wheel rim film after the final hot pressing molding has good mechanical strength. After being prepared into an air bag, it is not easy to break during the inflation process of the air bag and can withstand increased inflation pressure.

[0032] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0033] 1. A processing mold for a wheel rim film of the present invention is provided with an elastic demoulding structure on both the upper mold and the lower mold, and utilizes the pressing force between the upper and lower molds during the hot pressing forming process, so that the ejector pin in the elastic demoulding structure does not push the wheel rim film during the hot pressing forming of the wheel rim film, thereby avoiding affecting the forming of the wheel rim film; and utilizes the restorative deformation of the spring column, so that after the upper and lower molds are separated, the ejector pin pushes the wheel rim film in the direction where the wheel rim film is located, so that the wheel rim film does not adhere to the upper and lower molds, and is demoulded smoothly, thereby solving the problem that the wheel rim film is easily demoulded incompletely during demoulding when the wheel rim film is hot pressed and molded, and the wheel rim film partially adheres to the upper mold or the lower mold, thereby reducing the quality of the wheel rim film;

[0034] 2. The multi-layer heat-conducting structure of the mold core of the present invention greatly improves the heat transfer efficiency and also has a certain pressure buffering effect on the main structure;

[0035] 3. After the wheel rim is formed, the wheel rim film obtained by the present invention can be easily removed from the wheel rim or the intermediate mold without any residue;

[0036] 4. After the wheel rim film obtained by the present invention is prepared into an air bag, the air bag is not easy to break during the inflation process and can withstand increased inflation pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative work, among which:

[0038] Figure 1 It is a plan view of the lower mold of the present invention;

[0039] Figure 2 It is a plan view of the upper mold of the present invention;

[0040] Figure 3 It is a schematic diagram of the mold core structure of the present invention;

[0041] Figure 4 It is a cross-sectional view of the upper mold and the lower mold of the present invention;

[0042] Figure 5 The present invention Figure 4 A partial enlarged view of part A;

[0043] Figure 6 is a cross-sectional view of the mold core of the present invention;

[0044] Figure 7 It is a schematic structural diagram of the molding device of the present invention;

[0045] Figure 8 It is a side view of the wheel rim film of the present invention;

[0046] Fig. 9 It is a real picture of the wheel rim film after hot pressing forming of the present invention.

[0047] Markings in the figure: 1-lower mold, 2-upper mold, 3-cylinder, 4-spring column, 5-thrust pin, 6-plug, 7-base, 8-frame, 9-telescopic column, 10-roller, 11-lower mold core, 12-film traction mechanism, 13-main structure, 14-thermal conductive silicone layer, 15-aluminum layer, 16-flexible thermal conductive sheet, 21-upper mold core, 121-support column, 122-horizontal telescopic column. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0050] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0051] The features and performance of the present invention are further described in detail below in conjunction with the embodiments. Example 1

[0052] like Figure 1-8As shown, a wheel rim film processing mold provided by a preferred embodiment of the present invention comprises a matching lower mold 1 and an upper mold 2, wherein the lower mold 1 and the upper mold 2 are both provided with an electric heating structure, a plurality of lower mold cores 11 protruding upward are provided on the top surface of the lower mold 1, all the lower mold cores 11 are arranged one by one and evenly along the long side direction of the lower mold 1, and a cavity is formed between two adjacent lower mold cores 11; a plurality of upper mold cores 21 protruding downward are provided on the bottom surface of the upper mold 2, all the upper mold cores 21 are arranged one by one along the long side direction of the upper mold 2, and the upper mold cores 21 and the lower mold cores 11 are arranged alternately, the upper mold cores 21 correspond one by one to the cavity on the lower mold 1, and the upper mold cores 21 match the cavity shapes on the lower mold 1;

[0053] A plurality of elastic demoulding structures are installed on the lower mold 1 and the upper mold 2, and the elastic demoulding structures are evenly distributed between two adjacent lower mold cores 11 and between two adjacent upper mold cores 21;

[0054] The elastic demoulding structure comprises a cylinder 3 with an opening at one end, a spring column 4 is installed inside the cylinder 3, the spring column 4 is retracted in the axial direction of the cylinder 3, one end of the spring column 4 is connected and fixed to the sealing end of the cylinder 3, and an ejector pin 5 is installed on the other end of the spring column 4, the long side of the ejector pin 5 is parallel to the central axis of the cylinder 3, the tail of the ejector pin 5 is connected and fixed to the spring column 4, and the front end surface of the ejector pin 5 is arc-shaped; the open end of the cylinder 3 is detachably connected to a plug 6 for blocking the opening, and the outer end surface of the plug 6 is connected to the opening of the cylinder 3. The end faces are flat, and a small hole for the ejector 5 to pass through is opened on the plug 6; blind holes for installing the elastic demoulding structure are opened on the lower mold 1 and the upper mold 2, and the cylinder 3 is tightly connected to the inner wall of the blind hole. The open end of the blind hole is the end close to the middle area of ​​the lower mold 1 and the upper mold 2, and the front end of the ejector 5 faces the middle area of ​​the lower mold 1 and the upper mold 2. The end face of the open end of the cylinder 3 is flush with the corresponding top surface of the lower mold 1 or the bottom surface of the upper mold 2; when the spring column 4 in the elastic demoulding structure is in the original state, the front end of the ejector 5 passes through the plug 6 and is located outside the cylinder 3.

[0055] A plurality of elastic demolding structures are arranged in the channel formed between two adjacent lower mold cores 11 and in the channel formed between two adjacent upper mold cores 21 . All elastic demolding structures in the same channel are arranged one by one and evenly along the wide side of the corresponding lower mold 1 or upper mold 2 .

[0056] When the spring column 4 in the elastic demolding structure is in the original state, the front end of the ejector pin 5 passes through the plug 6 and is located outside the cylinder 3, wherein the front end of the ejector pin 5 on the lower mold 1 is located above the top surface of the lower mold core 11, and the front end of the ejector pin 5 on the upper mold 2 is located below the bottom surface of the upper mold core 21, and the distance between the front end of the ejector pin 5 and the corresponding top surface of the lower mold core 11 or the bottom surface of the upper mold core 21 is 1 mm.

[0057] The upper mold core 21 and the lower mold core 11 have the same mold core structure, the mold core structure is a triangular prism structure, the top surface of the mold core structure is an arc surface, the top surface of the lower mold core 11 faces upward, and the top surface of the upper mold core 21 faces downward;

[0058] The end face of the core structure is an isosceles triangle with a rounded vertex angle, the base angle β of the end face of the core structure is 45-50°, and the height H of the end face of the core structure is 4-5 mm. The core structure under this standard will not break the film.

[0059] The molding device containing the above-mentioned processing mold includes a base 7, a lower mold 1 is installed on the top surface of the base 7, an upper mold 2 is located above the lower mold 1, the upper mold 2 is connected and fixed to the base 7 through a frame 8, and a vertically installed telescopic column 9 is connected to the top of the upper mold 2, and the telescopic column 9 is installed on the frame 8; a heating structure is provided inside the lower mold 1 and the upper mold 2, and under the action of the telescopic column 9, the upper mold 2 and the lower mold 1 are pressed together to perform hot pressing molding on the wheel rim film between the upper mold 2 and the lower mold 1;

[0060] A roller 10 and a film traction mechanism 12 are also installed on the top surface of the base 7. The roller 10 is installed on the roller frame, and the roller frame is installed on the base 7. The roller 10 is rotatably connected to the roller frame. The roller 10 and the film traction mechanism 12 are respectively located on both sides of the lower mold 1. The rim film is evenly wound on the roller 10, and one end of the rim film passes through the area between the upper mold 2 and the lower mold 1 and is clamped by the film traction mechanism 12; the film traction mechanism 12 pulls the rim film on the roller 10 into the area between the upper mold 2 and the lower mold 1 for molding, and then pulls the molded rim film out of the area between the upper mold 2 and the lower mold 1 after the molding process.

[0061] The film traction mechanism 12 includes a vertically placed support column 121, which is located on one side of the lower mold 1 and has a traction spacing with the lower mold 1. The support column 121 is connected and fixed to the base 7. A horizontally placed horizontal telescopic column 122 is installed on the support column 121. The fixed end of the horizontal telescopic column 122 is connected and fixed to the support column 121, and a wheel rim film clamping structure is installed on the movable end of the horizontal telescopic column 122; the horizontal telescopic column 122 is telescoped along its axial direction to realize the traction of the wheel rim film.

[0062] The temperatures of the upper mold 2 and the lower mold 1 are both 85-86°C.

[0063] The wheel rim film prepared by using the above-mentioned processing mold and molding device is a film with continuous folds, the top surface of the folds is an arc surface, the side surface of the folds is a rectangular surface, the end surface of the folds is an isosceles triangle, and the base angle α of the isosceles triangle is 45-50°.

[0064] The wheel rim film comprises low-density polyethylene and polypropylene in a mass ratio of 3:2. The wheel rim film prepared under this formula can be deformed by compression at 85-86°C, and the wheel rim film will not be softened and produce fluidity at this temperature; and the wheel rim film after the final hot pressing molding has good mechanical strength. After being prepared into an air bag, it is not easy to break during the inflation process of the air bag and can withstand increased inflation pressure.

[0065] In the actual processing process, the wheel rim film formed by the up-blowing or down-blowing process is a double-layer film structure. After the two ends of the double-layer film are sealed and an inflation port is opened, an air bag can be formed.

[0066] The method of using the present invention is as follows: the film on the roller is pulled between the upper and lower molds by using a film traction mechanism, the wheel rim film is flattened on the lower mold core of the lower mold, and then the telescopic column presses down the upper mold. After the upper mold and the lower mold are pressed together, the mold cores of the upper and lower molds are staggered to form a cavity, and the wheel rim film is located inside the cavity. During the downward pressing process of the upper mold core 21, the ejector pin at the corresponding position on the lower mold is pushed downward, and the spring column connected to it is compressed during the downward movement of the ejector pin. After the spring column is shortened, the ejector pin is completely inserted into the cylinder, and the hot pressing of the wheel rim film by the upper mold core 21 is not affected. Similarly, the lower mold core pushes the ejector pin at the corresponding position of the upper mold upward, and the ejector pin is pushed into the cylinder under the deformation of the spring column, and the hot pressing of the wheel rim film by the lower mold core is not affected. After a period of pressing, embossing is formed on the surface of the wheel rim film, and then the upper mold is pulled upward by controlling the telescopic column. The upper mold is separated from the lower mold. After the upper and lower molds are separated, the force exerted by the upper and lower mold cores on the opposite ejectors is cancelled. Without the action of external force, the spring column returns to its original length, and the ejectors on the upper and lower molds will push the rim film toward the side where the rim film is located. The ejector on the upper mold will push the rim film downward away from the upper mold, and the ejector on the lower mold will simultaneously push the rim film upward away from the lower mold. As the distance between the upper and lower molds increases, the ejector on the upper mold will eventually detach from the rim film, and the ejectors on both sides of the rim film will not push the rim film at the same time. At this time, the rim film will naturally fall on the lower mold core and will not adhere to the mold cores on both sides. Finally, the rim film traction equipment quickly pulls the rim film out from between the upper and lower molds, and then manually shears the rim film to complete the hot pressing and demolding of the rim film. Example 2

[0067] In this embodiment, based on the embodiment 1, the core structure includes a solid main body structure 13 made of aluminum, the outside of the main body structure 13 is coated with a thermal conductive silicone layer 14, the outside of the thermal conductive silicone layer 14 is coated with an aluminum layer 15, and the outer wall of the aluminum layer 15 is coated with a polytetrafluoroethylene non-stick layer;

[0068] A plurality of flexible heat-conducting sheets 16 are installed inside the core structure. The flexible heat-conducting sheets 16 are in contact with the main structure 13, the heat-conducting silicone layer 14 and the aluminum layer 15. The flexible heat-conducting sheets 16 are graphene heat-conducting sheets.

[0069] The actual picture of the wheel rim film obtained by processing in the embodiment of the present invention is as follows: Fig. 9 shown. Comparative Example 1

[0070] In this embodiment, based on the embodiment 1, the core structure is a single solid aluminum structure. Comparative Example 2

[0071] This embodiment is based on the embodiment 2, but is different from the embodiment 2 in that the core structure does not include a graphene thermal conductive sheet. Comparative Example 3

[0072] This embodiment is based on the embodiment 2, but is different from the embodiment 2 in that the wheel rim film of the present invention comprises low-density polyethylene and polypropylene in a mass ratio of 1:1. Comparative Example 4

[0073] This embodiment is based on the embodiment 2, but is different from the embodiment 2 in that the wheel rim film of the present invention comprises low-density polyethylene and polypropylene in a mass ratio of 2:1. Comparative Example 5

[0074] This embodiment is based on the embodiment 2, but is different from the embodiment 2 in that the wheel rim film of the present invention does not include low-density polyethylene, but is a polypropylene film. Comparative Example 6

[0075] This embodiment is based on the embodiment 2, and is different from the embodiment 2 in that the wheel rim film of the present invention does not include polypropylene, but is a low-density polyethylene film.

[0076] Test Example 1

[0077] The thermal conductivity of the core structure in Example 2 and Comparative Examples 1 and 2 and the hot pressing time for the rim film to achieve the same hot pressing molding effect were tested. The results are shown in Table 1.

[0078] The thermal conductivity of the core structure of the present invention is detected by the existing steady-state method. The steady-state method is to apply a constant temperature difference on both sides of the material, measure the heat flow in a stable state, and thus calculate the thermal conductivity.

[0079] Hot pressing time: The time required for the rim film to be hot pressed between the upper mold and the lower mold. The formed rim film has continuous and structurally stable folds and can be used as an air bag.

[0080] Table 1 Thermal conductivity of mold core and hot pressing time of wheel rim film

[0081] Example 2 Comparative Example 1 Comparative Example 2 Thermal conductivity of the core structure 427W / (m·K) 230W / (m·K) 82W / (m·K) Hot pressing time of wheel rim film ≤10 seconds 15-18 seconds >30 seconds

[0082] Test Example 2

[0083] The tensile strength of the wheel rim films obtained after hot pressing molding in Example 2 and Comparative Examples 1-6 (hot pressing time is 10 seconds) was tested, and the results are shown in Table 2. The method for testing the tensile strength of the wheel rim film is prior art.

[0084] Table 2 Air bag pressure detection structure

[0085] Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Transverse tensile strength 45-48MPa <30MPa <20MPa <30MPa 38-40MPa 30-35MPa 15-20MPa Longitudinal tensile strength 48-50MPa <30MPa <20MPa <30MPa 38-40MPa 30-35MPa 15-20MPa

[0086] The rim film prepared by the invention has a tensile strength of 45-50 MPa and can be used for preparing bicycle rims.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions and improvements made by any technician familiar with the field within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A wheel rim film, characterized in that: The wheel rim film is a double-layer film structure with continuous folds, the top surface of the folds is an arc surface, the side surface of the folds is a rectangular surface, the end surface of the folds is an isosceles triangle, and the base angle α of the isosceles triangle is 45-50°; The wheel rim film comprises low-density polyethylene and polypropylene in a mass ratio of 3:2; The wheel rim film is prepared by a processing mold, wherein the processing mold comprises a matching lower mold (1) and an upper mold (2), wherein heating structures are provided inside the lower mold (1) and the upper mold (2), wherein a plurality of lower mold cores (11) protruding upward are arranged on the top surface of the lower mold (1), wherein all the lower mold cores (11) are arranged one by one and evenly along the long side direction of the lower mold (1), and a cavity is formed between two adjacent lower mold cores (11); wherein a plurality of upper mold cores (21) protruding downward are arranged on the bottom surface of the upper mold (2), wherein all the upper mold cores are arranged one by one along the long side direction of the upper mold (2), and the upper mold cores and the lower mold cores (11) are arranged in a staggered manner, wherein the upper mold cores (21) correspond one by one to the cavity on the lower mold (1), and the shapes of the upper mold cores and the cavity on the lower mold (1) match each other; A plurality of elastic demoulding structures are installed on the lower mold (1) and the upper mold (2), and the elastic demoulding structures are evenly distributed between two adjacent lower mold cores (11) and between two adjacent upper mold cores (21); The elastic demoulding structure comprises a cylinder (3) with an opening at one end, a spring column (4) is installed inside the cylinder (3), the spring column (4) is retracted in the cylinder (3) along the axial direction of the cylinder (3), one end of the spring column (4) is connected and fixed to the sealing end of the cylinder (3), and an ejector pin (5) is installed on the other end of the spring column (4), the long side of the ejector pin (5) is parallel to the central axis of the cylinder (3), the tail of the ejector pin (5) is connected and fixed to the spring column (4), and the front end surface of the ejector pin (5) is arc-shaped; the open end of the cylinder (3) is detachably connected to a plug (6) for sealing the opening, and the outer end surface of the plug (6) is connected to the outer end surface of the cylinder (3). The open end surface is flat, and a small hole for the ejector pin (5) to pass through is formed on the plug (6); a blind hole for installing an elastic demoulding structure is formed on the lower mold (1) and the upper mold (2), and the cylinder (3) is tightly connected to the inner wall of the blind hole. The open end of the blind hole is an end close to the middle area between the lower mold (1) and the upper mold (2), and the front end of the ejector pin (5) faces the middle area between the lower mold (1) and the upper mold (2). The open end surface of the cylinder (3) is flush with the corresponding top surface of the lower mold (1) or the bottom surface of the upper mold (2); when the spring column (4) in the elastic demoulding structure is in the original state, the front end of the ejector pin (5) passes through the plug (6) and is located outside the cylinder (3); The upper mold core and the lower mold core (11) have the same mold core structure, the mold core structure is a triangular prism structure, the top surface of the mold core structure is an arc surface, the top surface of the lower mold core (11) faces upward, and the top surface of the upper mold core faces downward; The end face of the mold core structure is an isosceles triangle with a rounded vertex angle, the base angle β of the end face of the mold core structure is 45-50°, and the height H of the end face of the mold core structure is 4-5 mm; The mold core structure comprises a solid main body structure (13) made of aluminum, the outside of the main body structure (13) is coated with a heat-conducting silicone layer (14), the outside of the heat-conducting silicone layer (14) is coated with an aluminum layer (15), and the outer wall of the aluminum layer (15) is coated with a polytetrafluoroethylene non-stick layer; A plurality of flexible heat-conducting sheets (16) are installed inside the core structure, the flexible heat-conducting sheets (16) are in contact with the main structure (13), the heat-conducting silicone layer (14), and the aluminum layer (15), and the flexible heat-conducting sheets (16) are graphene heat-conducting sheets; The temperatures of the upper mold and the lower mold are both 85-86°C.

2. A wheel rim film according to claim 1, characterized in that: A plurality of elastic demoulding structures are arranged in a channel formed between two adjacent lower mold cores (11) and in a channel formed between two adjacent upper mold cores (21), and all elastic demoulding structures located in the same channel are arranged one by one and evenly along the wide side of the corresponding lower mold (1) or upper mold (2).

3. A wheel rim film according to claim 1, characterized in that: When the spring column (4) in the elastic demoulding structure is in the original state, the front end of the ejector pin (5) passes through the plug (6) and is located outside the cylinder (3), wherein the front end of the ejector pin (5) on the lower mold (1) is located above the top surface of the lower mold core (11), and the front end of the ejector pin (5) on the upper mold (2) is located below the bottom surface of the upper mold core, and the distance between the front end of the ejector pin (5) and the corresponding top surface of the lower mold core (11) or the bottom surface of the upper mold core is 1 mm.

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