CN112549397A - Method for producing a structural component and structural component

Info

Abstract

Description

Claims

CN112549397A

Publication number: CN112549397A
Application number: CN201910917306.6A
Authority: CN
Inventors: 杨帆; 王永刚
Original assignee: Fujian Haiyuan New Material Technology Co ltd; Covestro Deutschland AG
Current assignee: Fujian Haiyuan New Material Technology Co ltd; Covestro Deutschland AG
Priority date: 2019-09-26
Filing date: 2019-09-26
Publication date: 2021-03-26

The application provides a method of manufacturing a structural component and a structural component. The manufacturing method comprises the following steps: 1) melting raw materials comprising polycarbonate or a blend of polycarbonate and acrylonitrile-butadiene-styrene, mixing the raw materials with fibers, and then extruding and cutting the mixture into preformed blanks with preset lengths; 2) maintaining the preform at a holding temperature and conveying the preform prior to compression molding; and 3) conveying the pre-formed blank to a die press and compression molding to form a structural component; wherein the temperature of the preformed blank is 240-320 ℃; the heat preservation temperature is 200-280 ℃; and the structural component is configured to have a projected area of 1 square meter or more in at least one projection direction. The manufacturing method has the advantages of simplicity, reliability, convenience in implementation, high efficiency and the like; the structural component has the advantages of small density, high strength, good mechanical property, high temperature resistance, good flame retardance and the like, and is suitable for the upper shell of the battery pack of the electric automobile.

Method for producing a structural component and structural component

Technical Field

The present application relates to the field of composite structural component manufacturing. More specifically, the present application relates to a manufacturing method for manufacturing structural components using polycarbonate or polycarbonate blends, aiming at manufacturing large-size structural components via an in-line blending long fiber reinforced thermoplastic (LFT-D) process. The application also relates to a structural component manufactured according to the above-described manufacturing method.

Background

Many applications require the use of large-sized structural components, such as the upper housing of an electric vehicle battery pack. Power battery pack components require testing to meet several national standards, such as external flame exposure combustion testing (GB/T31467.3), and air-tight testing (e.g., performed at 3.5 KPa), among others. Therefore, materials commonly used for manufacturing the upper case of the battery pack include metals (e.g., steel or aluminum alloys), thermosetting resin materials (e.g., thermosetting resin materials molded by SMC), polypropylene resins, and the like.

However, the density of the steel is very high (7.8 g/cm)³) Thus resulting in a structural component having a greater weight and also requiring the application of subsequent corrosion protection and insulation treatments.

The aluminum alloys are suitable for simple, plate-shaped components, in particular for structural components which are not deep-pored and have a non-complex cross-sectional shape. The aluminum alloy has simple production process and can balance the light weight and the cost. However, if a structural part with a complex geometry and a deep cavity is made of an aluminum alloy, additional modifications to the mold and process are required to deal with the change in the corners of the part and the product cross-section, which results in increased costs. At the same time, the mechanical properties of the structural member in these regions are weakened, since a deep draw ratio will result in a thinning of the walls of the structural member at the side walls and corners.

SMC molding scheme of thermosetting resin materialFor the manufacture of parts with complex geometries, a number of disadvantages remain. For example, thermosetting resin materials are non-recyclable materials and have a higher density (1.8 g/cm) than thermoplastic resin materials³) The molding cycle time is long (about 4-5 minutes is generally needed), and the problem of VOC odor exists in the process of processing and molding. The SMC-molded structural parts made of thermosetting resin materials have a high modulus, but have a low elongation at break and poor toughness. The SMC scheme of thermosetting resin material is susceptible to cracking during assembly and hermetic test if applied to the battery pack upper case.

An In-line Compounding Long Fiber Reinforced Thermoplastic-Direct (In-line Compounding Long Fiber Reinforced Thermoplastic-Direct) process may be used to manufacture structural components. Among them, the long fiber-reinforced thermoplastic may be abbreviated as LFT-D.

Although polypropylene resin (PP) can be used for forming a structural component with a larger size through an LFT-D process, the formed structural component has the defects of poor mechanical property, severe warping, modulus of 5000-600 MPa, poor flame retardance, incapability of passing a combustion test and the like, and the technical requirement of an upper shell of a battery pack cannot be met.

However, if injection molding is employed to manufacture large-sized structural parts based on thermoplastic resins such as Polycarbonate (PC) and polycarbonate Blend (PC Blend), the relatively high molding viscosity places high demands on molding pressure and mold clamping force. In the manufacture of large-sized structural parts, the required molding pressure and clamping force are generally outside the range of molding pressures and clamping forces that can be provided by conventional injection molding machines.

The chinese patent application CN103991204A discloses a LFT-D molding method of molded glass fiber reinforced PC. However, the machining tools and disclosed process conditions employed in CN103991204A cannot be used to manufacture large size structural components.

The Chinese patent application CN109130207A discloses a production process of an upper cover LFT-D of a flame-retardant battery case by adopting a glass fiber cloth aluminum foil. However, the solution disclosed in CN103991204A is intended to improve flame retardancy and fire resistance using a glass cloth aluminum foil, and a thermoplastic resin such as Polycarbonate (PC) and polycarbonate Blend (PC Blend) does not need to use a glass cloth aluminum foil to have the desired flame retardancy and fire resistance.

Chinese patent application CN109177209A discloses a molding process for manufacturing an upper case of a battery pack using a polymer matrix material such as a modified PP resin. However, the solution disclosed in CN109177209A is also not applicable to thermoplastic resins such as Polycarbonate (PC) and polycarbonate Blend (PC Blend).

Accordingly, there is a continuing interest in the art for methods of manufacturing large size parts of polycarbonate or polycarbonate blend materials and the resulting large size structural parts. It is desirable that new solutions are able to improve the production efficiency while ensuring the mechanical, fire-resistant and airtight properties of large-size structural components.

Disclosure of Invention

An object of an aspect of the present application is to provide a manufacturing method for a structural member, which is intended to manufacture a large-sized structural member by an in-line blending long fiber reinforced thermoplastic compression molding process using polycarbonate or a polycarbonate blend material. It is an object of another aspect of the present application to provide a structural component obtained by the above-described manufacturing method.

The purpose of the application is realized by the following technical scheme:

a method of manufacturing for a structural component, comprising the steps of:

1) melting raw materials comprising polycarbonate or a blend of polycarbonate and acrylonitrile-butadiene-styrene, mixing the raw materials with fibers, and then extruding and cutting the mixture into preformed blanks with preset lengths;

2) maintaining the preform at a holding temperature and conveying the preform prior to compression molding; and is

3) Conveying the pre-formed blank to a molding press and compression molding the pre-formed blank in the molding press to form a structural component;

in the step 1), the temperature of the preformed blank is 240-320 ℃; in the step 2), the heat preservation temperature is 200-280 ℃; and in step 3), the structural component is configured to have a projected area of 1 square meter or more in at least one projection direction.

In the above manufacturing method, optionally, step 1) includes: heating, plasticizing and melting the raw material in a first extruder to obtain a first melt; mixing the fibers with the first melt in a second extruder to obtain a second melt; and continuously extruding and cutting the second melt to obtain a preform; and is

In step 3), the molding press comprises a mold and a temperature control device.

In the above manufacturing method, optionally, wherein the raw material comprises polycarbonate, the temperature control device comprises a rapid thermal cycling rapid thermal quenching device, the temperature control device operating to periodically vary a temperature of a mold cavity of the mold between a first predetermined temperature and a second predetermined temperature lower than the first predetermined temperature, the rapid thermal quenching device comprising:

a first fluid source configured to provide a first working fluid;

a second fluid source configured to provide a second working fluid;

a first fluid circuit disposed at a first distance from a perimeter of the mold cavity and in selective fluid communication with a first fluid source or a second fluid source; and

a second fluid circuit disposed at a second distance from a perimeter of the mold cavity.

In the above-described manufacturing method, alternatively, at the time of press molding, first, the first working fluid is supplied to the first fluid circuit to adjust the temperature of the mold cavity to a first predetermined temperature, then the preform is supplied into the mold cavity while cutting off the supply of the first working fluid, discharging the first working fluid in the first fluid circuit, and the second working fluid is supplied to the first fluid circuit to adjust the temperature of the mold cavity to a second predetermined temperature; wherein the second fluid circuit is configured for delivering an insulating fluid to provide a constant mold temperature.

In the above manufacturing method, optionally, the first working fluid is steam or high-temperature water, the second working fluid is cooling water, the temperature of the first working fluid is higher than a first predetermined temperature, and the temperature of the second working fluid is lower than a second predetermined temperature.

In the above manufacturing method, optionally, the first fluid circuit includes a plurality of first fluid passages arranged in parallel with each other, wherein a first pitch between adjacent first fluid passages is in a range of 35-60mm, a first distance is in a range of 8-25mm, and each first fluid passage has a first diameter in a range of 5-20mm, respectively; and is

The second fluid circuit comprises a plurality of second fluid channels arranged parallel to each other, wherein a second distance between adjacent second fluid channels is 50-70mm, each second fluid channel has a second diameter of 20-30mm, respectively, and the first distance is smaller than the second distance, and the second fluid circuits are spaced parallel to each other at a distance of 15-30mm from the first fluid circuits.

In the above manufacturing method, optionally, four to eight first fluid channels are connected in parallel to form a single group of first parallel channels, and the multiple groups of first parallel channels are connected in series to form a first fluid circuit; and/or

Four to eight second fluid channels are connected in parallel to form a single set of second parallel channels, and multiple sets of second parallel channels are connected in series to form a second fluid circuit, or a second fluid circuit is formed by a plurality of second fluid channels in series.

In the above production method, optionally, in step 1), the polycarbonate is heated and plasticized after being dried at 100 ℃ for at least 4 hours, and the temperature of the first melt is 280-320 ℃; the first melt was output through a nozzle to a second extruder for mixing with the fibers, the temperature of the nozzle was 290 ℃ to 300 ℃, and the temperature profile of the barrel in the second extruder was: the front section is 280 plus 290 ℃, the middle section is 270 plus 280 ℃ and the rear section is 250 plus 260 ℃; in step 3), the first predetermined temperature is at least 130 ℃ and the second predetermined temperature is at least 80 ℃.

In the above manufacturing method, optionally, the raw material includes a polycarbonate and acrylonitrile-butadiene-styrene blend, and the temperature control device includes a mold temperature machine; in the step 1), the polycarbonate and acrylonitrile-butadiene-styrene blend is heated and plasticized after being dried for 4 hours at 80 ℃, and the temperature of the first melt is 240-270 ℃; the first melt was output through a nozzle to a second extruder for mixing with the fibers, the temperature of the nozzle was 255-: the front section is 230-240 ℃, the middle section is 225-235 ℃ and the rear section is 220-230 ℃; in step 3), the mold temperature machine is configured to set the mold temperature to 60-100 ℃.

In the above manufacturing method, optionally, the weight percentage of the polycarbonate or the polycarbonate and acrylonitrile-butadiene-styrene blend in the structural member is 60 to 90%.

In the above manufacturing method, optionally, the fiber is selected from glass fiber, carbon fiber, aramid fiber, natural fiber, or a combination thereof, wherein the fiber has a length of 15-35 mm.

In the above manufacturing method, optionally, the fiber may be 10 to 40% by weight in the structural member.

In the above-described manufacturing method, optionally, in step 2), the preform stock is conveyed on a conveyor belt with a keep-warm heating cover plate, and the keep-warm heating cover plate is configured to be closed to keep the preform stock at the keep-warm temperature.

A structural component is made by the above-described manufacturing method.

In the above structural component, optionally, the structural component is an upper case of a battery pack for an electric vehicle.

The manufacturing method for the structural component and the structural component have the advantages of high reliability, convenience in manufacturing, high production efficiency and the like, and can provide a solution for manufacturing a large-size structural component by an online long fiber blended reinforced thermoplastic plastic compression molding process by adopting polycarbonate or polycarbonate blended materials.

Drawings

The present application will be described in further detail below with reference to the drawings and preferred embodiments, but those skilled in the art will appreciate that the drawings are only drawn for the purpose of illustrating the preferred embodiments and therefore should not be taken as limiting the scope of the present application. Furthermore, unless specifically stated otherwise, the drawings are intended to be conceptual in nature or configuration of the described objects and may contain exaggerated displays and are not necessarily drawn to scale.

Fig. 1 is a schematic view of the structure of a production line for a press molding process.

Fig. 2 is a schematic view of the structure of the die press of fig. 1.

Fig. 3 is a schematic diagram of the first fluid circuit of fig. 2.

Fig. 4 is a schematic diagram of the first and second fluid circuits of fig. 2.

Fig. 5 is a schematic view showing a connection relationship of the fluid passages in fig. 2.

Fig. 6 is a perspective view of a product obtained using the production line shown in fig. 1.

Detailed Description

Hereinafter, preferred embodiments of the present application will be described in detail with reference to the accompanying drawings. Those skilled in the art will appreciate that the descriptions are illustrative only, exemplary, and should not be construed as limiting the scope of the application.

First, it should be noted that the terms top, bottom, upward, downward and the like are defined relative to the directions in the drawings, and they are relative terms, and thus can be changed according to the different positions and different practical states in which they are located. These and other directional terms should not be construed as limiting terms.

Furthermore, it should be further noted that any single technical feature described or implied in the embodiments herein, or any single technical feature shown or implied in the figures, can still be combined between these technical features (or their equivalents) to obtain other embodiments of the present application not directly mentioned herein.

It should be noted that in the various figures, like reference numerals designate similar or substantially similar components.

Fig. 1 is a schematic view of the structure of a production line for a press molding process. Wherein, the production line 100 for the compression molding process includes: a first extruder 110, a second extruder 120, a conveyor belt 130, a conveying device 140, a molding press 150, and a temperature control device, not shown.

The first extruder 110 is provided with a first hopper 111 and a nozzle 112. The first hopper 111 is for receiving the raw material 10 that has been subjected to the through-air drying process. The raw material 10 is subjected to shear heating plasticization in a plasticizing unit or barrel in the primary extruder 110, so that the raw material 10 becomes a molten state, so that a continuously extruded primary melt 11 is obtained at the nozzle 112. The temperature of the first melt 11 may be set as desired, and may be set to 310 ℃. In one embodiment of the present application, the temperature of the first melt in the first extruder 110 can be set by one skilled in the art according to actual needs. In one embodiment of the present application, the temperature of the nozzle 112 may be 290-300 ℃.

In the examples of the present application, the raw material 10 is heated and the temperature is gradually increased in the first extruder 110. As recognized by those skilled in the art, the feedstock 10 may be a thermoplastic compound, thermoplastic, or thermoplastic resin. After heating to a certain temperature, plasticization of the raw material 10 will occur, so that the solid form of the raw material 10 is gradually converted into a molten form.

The feedstock 10 in the embodiments disclosed herein comprises a thermoplastic resin, such as Polycarbonate (PC) or a polycarbonate Blend (PC Blend). The polycarbonate Blend (PC Blend) includes Polycarbonate (PC) plus at least one selected from the group of polypropylene (PP), Polyamide (PA), acrylonitrile-butadiene-styrene (ABS) and other compositions. In one embodiment of the present application, the starting material 10 is Polycarbonate (PC). In another embodiment of the present application, the feedstock 10 is a Polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) blend. The raw material 10 has been dried in a not shown through-air drying device for a predetermined length of time and at a predetermined temperature before being fed into the first hopper 111. For example, in one embodiment of the present application, feedstock 10 comprising Polycarbonate (PC) is dried in a through-air oven at 100 ℃ for 4 hours. In another embodiment, a feedstock 10 comprising a blend of Polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) is dried in a through-air oven at 80 ℃ for 4 hours.

The second extruder 120 is provided with a fiber cutter 121, a second hopper 122, and an extrusion head 123. The fiber cutter 121 is configured to cut the continuous fibers 20 into fibers 21 having a desired length. The desired length may be set according to the actual need, and may be, for example, 15-35 mm. In one embodiment of the present application, the length of the fibers is set to 25 mm.

The continuous fibers 20 and fibers 21 may be selected from glass fibers, carbon fibers, aramid fibers, natural fibers, and mixtures of one or more of the foregoing. In one embodiment of the present application, the continuous fibers 20 may be glass fibers commercially available from owens corning. The glass fibers may be surface treated to assist in bonding with the first melt 11.

The second hopper 122 is for receiving the first melt 11 and the fibers 21, and the first melt 11 and the fibers 21 are mixed in the second extruder 120. The supply of raw material 10 and continuous fibers 20 may determine the weight ratio of raw material to fibers in the final product. For example, the continuous fibers 20 may be present in a weight ratio of between 10% and 40% of the total weight of the final product. In one embodiment of the present application, the weight ratio of the feedstock 10 to the continuous fibers 20 is 70: 30. In one embodiment of the present application, a barrel is included in the secondary extruder 120 through which the raw materials and fibers are conveyed and which needs to be provided with a temperature to ensure mixing. For example, in embodiments where the feedstock 10 is polycarbonate, the front section of the barrel in the second extruder 120 may have a temperature of 280-290 ℃, the middle section may have a temperature of 270-280 ℃, and the back section may have a temperature of 250-260 ℃. In embodiments where the feedstock 10 is a blend of polycarbonate and acrylonitrile butadiene styrene, the front section of the barrel in the second extruder 120 may have a temperature of 230-240 ℃, the middle section of the barrel may have a temperature of 225-235 ℃, and the rear section of the barrel may have a temperature of 220-230 ℃.

At least one of the first extruder 110 and the second extruder 120 may be a device with screws or twin screws, including but not limited to a twin screw machine, etc., so that the barrels themselves in the first extruder 110 and the second extruder 120 and the raw materials located inside the barrels can be rotated in the direction indicated by the arrow schematically shown in fig. 1 by the driving of an external force. For example, at least the second extruder 120 may be provided with twin screw devices to effect mixing of the raw materials with the fibers.

Extrusion head 123 is used to continuously extrude second melt 22. The second melt 22 may also have a corresponding second melt temperature, which may be 310 ℃, for example. Similarly, the temperature of the second melt in the second extruder 120 can also be set by one skilled in the art according to actual needs. In one embodiment, the feedstock 10 is polycarbonate and the temperature of the second melt 22 is 280-320 ℃. In another embodiment, the feedstock 10 is a polycarbonate and acrylonitrile butadiene styrene blend and the temperature of the second melt 22 is 240-. Extrusion head 123 may be provided with a desired cross-sectional shape to obtain second melt 22 having the desired cross-sectional shape. For example, the desired cross-sectional shape may be rectangular or square.

The conveyor belt 130 is provided with an extrudate cutter 131 and a heat-insulating heating cover 132. An extrudate cutting apparatus 131 is used to cut the second melt 22 to form the preform 30. In one embodiment of the present application, the preform blank 30 is provided having a relatively thick blank thickness, for example a blank thickness of 30-50 mm. In another embodiment, the blank thickness is set to about 40 mm. The preform 30 may have a temperature of 240 ℃ and 320 ℃, for example, a temperature approximately equal to the temperature of the second melt 22. The preform 30 is conveyed by a belt 130, a heat insulating cover plate 132 is provided on the belt 130, and the preform 30 is conveyed by the belt 130 under the heat insulating cover plate 132. The insulated heating cover plate 132 may be configured to be closed and provide an insulated temperature of about 200-280 ℃, which facilitates maintaining the preform blank 30 at the desired insulated temperature. In one embodiment of the present application, the incubation temperature is about 250 ℃. Thus, after the preform 30 is formed by severing the second melt 22, the temperature of the preform 30 will be gradually adjusted (e.g., lowered or raised) to the holding temperature and conveyed on the conveyor belt 130 while being maintained at approximately the holding temperature.

The purpose of providing a thicker blank thickness and/or maintaining a higher holding temperature is to slow down the rate of heat dissipation from the preform 30 so that the preform 30 can be brought to the desired temperature before being transferred to the next processing step, facilitating the subsequent press forming operation.

Further, the preform 30 may have a predetermined length. The desired length of the preform may be determined generally, for example, based on the cross-sectional dimensions of the extrusion head 123, the number of preforms 30 required for each press forming operation, and the size and weight of the final product. By setting the operation timing of the extrudate cutting apparatus 131 and the conveying speed of the conveyor belt 130, a desired predetermined length can be obtained. It will be readily appreciated that the cross-section of the preform 30 is generally similar to the cross-section of the extrusion head 123. The cross-sectional dimension may be any suitable geometric shape including, but not limited to, a square, a rectangle, a trapezoid, a portion of a circle or an ellipse, and the like.

The conveying device 140 may be a robot or robotic arm to convey the preform 30 from the belt 130 to the die press 150 for further press forming operations.

The molding press 150 may include a mold and a temperature control device. The specific configuration of the die press 150 will be explained in detail below. The molding press 150 according to one embodiment of the present application is intended to provide a mold temperature of 60 to 120 ℃, and the molding pressure provided by the molding press 150 is 1500-. In one embodiment of the present application, the molding press 150 provides a molding pressure of 3200 tons. In one embodiment of the present application, the molding press employs hydraulic or liquid pressure to perform the molding. However, according to other embodiments, other suitable pressure sources may be employed.

Therefore, the above-mentioned production line is used for carrying out a manufacturing method of a structural component according to an embodiment of the present application, comprising the steps of:

1) through-air drying a feedstock comprising polycarbonate or a blend of polycarbonate and acrylonitrile-butadiene-styrene;

2) conveying the dried raw materials to a first extruder for shearing, heating and plasticizing to obtain a molten first melt;

3) conveying the first melt through a nozzle to a second extruder while conveying the fiber into the second extruder to mix with the first melt to obtain a second melt;

4) continuously extruding the second melt through an extrusion head;

5) cutting the extruded second melt by an extruded material cutting device to obtain a preformed blank;

6) conveying the preformed blank in a heat preservation state, for example, conveying the preformed blank by a conveying belt with a heat preservation heating cover plate;

7) and conveying the preformed blank to a die in a die press, and carrying out die pressing.

Fig. 2 is a schematic view of the structure of the die press of fig. 1. The molding press 150 provides an upper mold 151 and a lower mold 152, and also has a rapid thermal cycle molding (RHCM) rapid thermal temperature control device 160. The temperature control device 160 includes: a first fluid source 161 for providing a first working fluid, a second fluid source 162 for providing a second working fluid, a first valve 163 for regulating the output of the first and second working fluids, one or more fluid circuits provided in the upper and lower dies 151 and 152, a second valve 164 for dividing the working fluid, and a drain passage 165 for draining the working fluid.

The upper and lower dies 151 and 152 are configured to provide a pressing pressure to press-form the preform 30 into a desired shape. In the illustrated embodiment, the upper die 151 and the lower die 152 have been compressed and the preform 30 has been press-molded in the vertical direction. At least a first fluid circuit 1 and a second fluid circuit 2 are provided in the upper die 151 and the lower die 152. The first fluid circuit 1 and the second fluid circuit 2 each comprise a plurality of fluid channels arranged in parallel. For example, the first fluid circuit 1 may be disposed around the bottom edge of the upper die 151 and the top edge of the lower die 152 such that each fluid channel is approximately equidistant from the bottom edge of the upper die 151 and the top edge of the lower die 152. Similarly, the second fluid circuit 2 may also be disposed around the bottom edge of the upper die 151 and the top edge of the lower die 152 such that each fluid channel is approximately equidistant from the bottom edge of the upper die 151 and the top edge of the lower die 152. This facilitates each fluid circuit providing a substantially uniform heating or cooling capacity around the preform 30.

The first fluid source 161 is configured for delivering a first working fluid to the first fluid circuit 1, the first working fluid having a temperature higher than a first predetermined temperature, so as to heat the temperature of the mold cavity (i.e., the space between the upper and lower dies 151, 152) to the first predetermined temperature. In one embodiment of the present application, the first working fluid may be high temperature water or steam, for example, may be water vapor having a temperature of about 180 ℃, or water or steam having a temperature above 120 ℃. As used herein, "high temperature water" refers to water having a temperature of at least 100 ℃ or above 120 ℃. The first predetermined temperature may be a temperature between 100 and 150 ℃, for example 130 ℃.

The second fluid source 162 is configured for delivering a second working fluid to the first fluid circuit 1, the second working fluid having a temperature lower than the first predetermined temperature, so as to cool and maintain the temperature of the mold cavity to and at a second predetermined temperature. In one embodiment of the present application, the second working fluid may be cooling water, for example, cooling water having a temperature of 25 ℃. The second predetermined temperature may be a temperature between 60 and 100 ℃. In one embodiment of the present application, the second predetermined temperature is determined by the temperature at the mold cavity retainer plate, and it is desirable that the second predetermined temperature is about 80 ℃.

In use, the first valve 163 is first adjusted to deliver the first working fluid from the first fluid source 161 to the first fluid circuit 1 to heat the mould cavity to a first predetermined temperature. Then, the robot 140 conveys the preform 30 from the belt 130 to between the upper and lower dies 151 and 152, and is compressed by the upper and lower dies 151 and 152. At the same time, the fluid supply of the first fluid source 161 is cut off and air is blown into the first fluid circuit 1 so as to force the first working fluid in the first fluid circuit 1 to move to the second valve 164. At the second valve 164, the water vapor is vented through a drain 165, and the liquid water is recycled to the temperature control device 160 for reuse. Furthermore, the first valve 163 is regulated so as to cut off the supply of the first working fluid to the first fluid circuit 1 and to deliver the second working fluid from the second fluid source 162 to the first fluid circuit 1 so as to regulate the temperature of the mould cavity to a second predetermined temperature.

Furthermore, the second fluid circuit 2 may be in fluid communication with a not shown source of a holding fluid and a holding fluid is provided within the second fluid circuit 2 in order to provide a constant mould temperature. In one embodiment of the present application, the insulating fluid is water having a temperature. In another embodiment of the present application, the second fluid circuit 2 is configured to aim at providing a constant die temperature of about 70-100 ℃, for example about 80 ℃.

To summarize, the temperature control device of the present application operates to periodically vary the temperature of the mold cavity of the mold between a first predetermined temperature and a second predetermined temperature that is lower than the first predetermined temperature. Therefore, the higher first predetermined temperature of the mold cavity can delay the temperature of the preform 30 from dropping when the preform 30 comes into contact with the mold cavity, thereby avoiding a large change in warpage of the final formed structural member. After the preform 30 begins to be compression molded, the temperature of the mold cavity is rapidly adjusted to a second predetermined temperature, thereby enabling faster cooling of the final molded structural part, reducing molding time, and improving production efficiency.

To ensure that the above-described operation is completed, a polymer material may be disposed around the mold cavity to form the insulation layer 153.

According to actual needs, the first working fluid, the second working fluid and/or the heat preservation fluid can adopt water or water vapor, and can also be any other suitable heat conduction medium.

Fig. 3 is a schematic diagram of the first fluid circuit of fig. 2. The first spacing D1 between the individual first fluid channels in the first fluid circuit 1 may be configured to be between 35-60mm, for example may be 45 mm. The first distance H1 of each first fluid channel from the surface of the mold cavity may be 8-25mm, for example, may be 15 mm. Each first fluid passage is configured to have a circular cross-section and may have a first diameter R1 of 5-20mm, respectively, and the first diameter R1 may be 15mm, for example.

Fig. 4 is a schematic diagram of the first and second fluid circuits of fig. 2. As shown, the second spacing D2 between each second fluid passage in the second fluid circuit 2 may be 40-80mm, such as 65 mm. The second fluid channel is disposed at a greater distance from the surface of the mold cavity than the first fluid channel, and the second fluid channel may be spaced apart from the first fluid channel by a distance H2 of 20-40mm, such as 25 mm. Each of the second fluid passages may be respectively configured to have a circular cross-section and a second diameter R2, and the second diameter R2 may be 20-40mm, such as 24 mm.

Embodiments of the present application provide the first fluid channel at a closer distance from the mold cavity than the second fluid channel such that a first distance of the first fluid channel from the mold cavity is less than a second distance of the second fluid channel from the mold cavity. For example, in the illustrated embodiment, the first distance is 15mm and the second distance is 40 mm.

Fig. 5 is a schematic view showing a connection relationship of the fluid passages in fig. 2. Fig. 5 shows in an exemplary manner the structure of an embodiment of the first fluid circuit 1. The first fluid circuit 1 includes plural sets of first

fluid passages

1a, 1b, and 1c connected in series, and these plural sets of first

fluid passages

1a, 1b, and 1c are connected end to form a reciprocating fluid passage structure. In use, the first or second working fluid flows in the direction indicated by arrows a1, a2, A3 and a4 in sequence and through the sets of first

fluid passages

1a, 1b and 1c such that the first or second working fluid substantially heats or cools the mold cavity.

Further, although it is shown in the drawings that each of the groups of first

fluid passages

1a, 1b, and 1c includes four parallel first fluid passages, between four and eight parallel first fluid passages may be provided as necessary, including five, six, or seven parallel first fluid passages, for example. Although not shown explicitly, it is readily understood that the second fluid circuit 2 may also have a similar configuration as described above. In one embodiment of the present application, the second fluid circuit 2 is configured to be formed of a plurality of fluid passages in series, without having a parallel configuration similar to the first fluid circuit 1.

Fig. 6 is a perspective view of a product obtained using the production line shown in fig. 1. Wherein the product 200 is formed by press-molding the preform 30 by the upper mold 151 and the lower mold 152, and the product 200 has a projected area of 1 square meter or more in at least one projection direction. In other embodiments, the product 200 has a projected area of at least 1.2, 1.5, 1.8, or 2 square meters. In one embodiment, the product 200 is an upper case of an electric vehicle battery pack. The battery pack may be, for example, a power battery for driving an electric vehicle.

As used herein, projected area refers to the area of the projected outline seen on one of the six side views of product 200. For example, for an upper housing of an electric vehicle battery pack, the projected area may refer to the area of the upper housing as viewed in a top view or in a vertical/gravitational direction. In other words, the projected area may refer to an orthographic area on a horizontal plane when the upper case of the electric vehicle battery pack is mounted in place. The projection direction can be the mold closing direction of the mold or parallel to the mold closing direction of the mold. The mold clamping direction refers to a direction in which the upper mold 151 moves toward the lower mold 152. In one embodiment of the present application, the clamp direction is substantially vertical.

In one aspect, the product 200 is required to pass industry standard tests, such as air tightness and fire tests. The polycarbonate (especially after being reinforced by fibers) has better mechanical property, high heat resistance, excellent flame retardant property and self-restitution. The char layer formed after the polycarbonate is burned can also block the fire and reduce the impact of high temperature and fire on the resin, which helps the product 200 pass the external fire test of the battery pack.

On the other hand, the LFT-D process can help to obtain longer fiber lengths on the final product than injection molding, help to improve mechanical properties (especially in terms of impact resistance) and pass air-tightness tests. In one embodiment of the present application, the length of the fibers in the product 200 is between 2-10 mm. The fibers have a diameter of about 11-17 μm.

By adopting the rapid thermal cycle molding technology to control the mold temperature, the requirements of different stages can be met, the production period is shortened, and the mass production is possible. The high die temperature helps to offset heat loss from the preform on the conveyor belt while waiting for the next forming cycle and from exposure to air during transport. The working fluid is adopted for cooling, so that the heat in the deep melting material can be effectively taken away, the post-shrinkage effect is reduced to the maximum extent, and the warping amount of the structural component is reduced.

By using the production line shown in fig. 1 and the molding press 150 and the temperature control device 160 shown in fig. 2 to 5, a product can be produced using Polycarbonate (PC) and glass fiber. For example, in one embodiment herein, the Polycarbonate (PC) has a melt index MVR of 9 cm ³10 min (300 ℃, 1.2 kg), tensile modulus of 2400 MPa, and notched impact strength of 12 KJ/m²。

By using the LFT-D line and a conventional mold temperature machine, a blend of Polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) and glass fibers can be used to produce a product. The blend of Polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) may have a melt index MVR of 17 cm ³10 min (240 ℃, 5 kg), tensile modulus of 2700 MPa, and notched impact strength of 30 KJ/m²。

The properties of the above-mentioned raw materials are shown in table 1 below.

Serial number	Performance index	Detection standard	PC+ABS	PC
						1	Tensile modulus (MPa)	ISO 527-1,2	2700	2400
2	Tensile Strength (MPa 0)	ISO 527-1,2	65	66
					3	Elongation at Break (%)	ISO 527-1,2	>50	120
4	Notched impact strength (23 ℃ C., KJ/m2)	ISO 180-A	30	65
					5	Density (g/cm)³)	ISO 1183-1	1.18	1.2
6	Vertical combustion	UL94	V-0 (1.5mm)	V-0 (1.5mm)

Table 1 properties of the feedstock.

The properties of the glass fiber material are shown in table 2 below.

Table 2 properties of the glass fibers.

The present application also tested the performance of products made from polypropylene (PP) and products made by the SMC process for comparison with the manufacturing methods and structural components disclosed above.

Polypropylene (PP) is also formed to make the same parts using an in-line co-extrusion process. Specifically, the dried polypropylene pellets are subjected to shear heating plasticization by a plasticizing unit of a first extruder through a feeding hopper, and the first melt temperature is set to 240 ℃. The first melt was continuously extruded through a nozzle and flowed into a second hopper on a second extruder. The continuous glass fiber was cut into a fiber having a length of 25mm by a fiber cutter. The plasticized first melt was fed into a second hopper simultaneously with the chopped fibers, wherein the weight ratio of polypropylene (PP) to fibers was 70: 30. Polypropylene (PP) and fiber were thoroughly blended by twin screws in a secondary extruder and then continuously extruded through an extrusion head at a melt temperature of 240 ℃ into a high temperature billet of rectangular cross section. And obtaining a preformed blank through an extrusion material cutting device, wherein when the preformed blank passes through a conveyor belt with a heat-preservation heating cover plate, the heat-preservation heating cover plate is in a closed state and provides a heat source temperature of 200 ℃. Grabbing the preformed blank by a manipulator and placing the preformed blank on a die, and closing the die and performing compression molding by a molding press. Finally, a structural part in the shape of a product as shown in fig. 2 is obtained. The molding pressure of the molding press was 3200 tons and a conventional mold temperature machine was used to provide a constant mold temperature of 23 ℃.

The SMC process for thermosetting resin materials involves cutting SMC sheets to the shape and size of the product, then stacking the multilayer sheets to the specified thickness and placing them in a mold. The mold surface temperature was maintained at 150 ℃. The mold was closed and mold clamping pressure was applied to compress the SMC sheet, after a cure time of 4 minutes, the mold was opened and the product was ejected from the mold.

The results of the product performance tests made with the above materials are shown in table 3, where the sample bar sampling is the melt flow direction, which is the fiber orientation direction.

Table 3 comparison of material performance test results.

Table 4 compares other parameters and test results for products made from the above materials.

Material

Process for the preparation of a coating

Density g/cm³

Tensile modulus MPa

Volume cm of the product³

Product weight Kg

Amount of deformation of product

Combustion test

Airtightness test (3.5 KPa)

SMC

Die pressing

1.80

11000

6197

13.10

Very small

By passing

Can only pass through<3.0Kpa

PP

Die pressing

1.31

5080

6197

9.53

Big (a)

Can not pass through

By passing

PC

Die pressing

1.44

9070

6197

10.48

Is smaller

By passing

Table 4.

In summary, compared with the prior art, the technical solution of the present application has at least the following advantages:

1. the resulting articles obtained by the present application have better strength and impact properties than articles made from existing thermoplastic resins, especially over conventional reinforcement materials.

2. Compared with polypropylene (PP), the final product obtained by the method has greatly improved properties in tensile modulus, tensile strength and notch impact strength, and the reinforced polycarbonate composite material still shows excellent thermal stability and flame retardance. Therefore, the upper shell of the battery pack of the electric automobile prepared according to the embodiment of the application can pass the fire test specified by the national standard GB/T31467.3 and the UL 94V 0 test at 2.0 mm.

3. Compared with a thermosetting resin material SMC (sheet molding compound) process, the final product obtained by the method has better performance in elongation at break and is easier to pass a test of air tightness, and the tensile modulus is 8000-9000 and the tensile modulus is 1.41-1.44 g/cm³The density can reach the same natural frequency and can reduce weight by about 20 percent. The present application utilizes recyclable thermoplastic materials and has a shorter molding cycle time (less than 90 seconds). The SMC process requires a long curing time, so the molding cycle is generally 4-5 minutes.

4. The preparation method based on the invention can mold the parts with large size and complex geometric shape. By adopting the temperature control device 160, the melt of the material can show better flowing property and longer flowing distance in the die cavity, and the problem that a large-size complex-structure product is difficult to mold based on a polycarbonate and polycarbonate blend material is further solved.

5. By the cooling circuit layout and the linking mode according to the application, expected mold temperature can be provided, and the molding period can be shortened, so that high-efficiency production in large batch can be realized.

6. The resulting structural member is prepared with low density, high strength, impact resistance, and excellent flame retardancy. The structural component is suitable for the upper cover of the battery pack of the electric automobile, can meet the safety requirement of a lithium ion power storage battery for the electric automobile, and passes the air tightness and burning test specified by the national standard GB/T31467.3.

This written description discloses the application with reference to the drawings, and also enables one skilled in the art to practice the application, including making and using any devices or systems, selecting appropriate materials, and using any incorporated methods. The scope of the present application is defined by the claims and encompasses other examples that occur to those skilled in the art. Such other examples are to be considered within the scope of protection defined by the claims of this application, provided that they include structural elements that do not differ from the literal language of the claims, or that they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Serial number

Performance index

Glass fiber

Tensile modulus (MPa)

Tensile Strength (MPa)

Elongation at Break (%)

Diameter (μm)

Linear density (Tex)

1. A method of manufacturing for a structural component, comprising the steps of:

2) maintaining the preform at a holding temperature and conveying the preform before press molding; and is

3) Conveying the pre-formed blank to a press and press-forming the pre-formed blank in the press to form a structural component;

characterized in that, in the step 1), the temperature of the preformed blank is 240-320 ℃; in the step 2), the heat preservation temperature is 200-280 ℃; and in step 3), the structural component is configured to have a projected area of 1 square meter or more in at least one projection direction.

2. The manufacturing method according to claim 1, characterized by comprising, in step 1): heating, plasticizing and melting the raw material in a first extruder to obtain a first melt; mixing fibers with the first melt in a second extruder to obtain a second melt; and continuously extruding and cutting said second melt to obtain said preform; and is

3. The manufacturing method according to claim 2, wherein the raw material comprises polycarbonate, the temperature control device comprises a rapid thermal cycling rapid thermal quenching device, the temperature control device is operative to periodically vary a temperature of a mold cavity of the mold between a first predetermined temperature and a second predetermined temperature lower than the first predetermined temperature, the rapid thermal quenching device comprises:

a first fluid source configured to provide a first working fluid;

a second fluid source configured to provide a second working fluid;

a first fluid circuit disposed at a first distance from a perimeter of the mold cavity and in selective fluid communication with the first fluid source or the second fluid source; and

4. The manufacturing method according to claim 3, wherein, at the time of press molding, first a first working fluid is supplied to the first fluid circuit to adjust the temperature of the mold cavity to the first predetermined temperature, then the preform is supplied into the mold cavity while cutting off the supply of the first working fluid, discharging the first working fluid within the first fluid circuit, and a second working fluid is supplied to the first fluid circuit to adjust the temperature of the mold cavity to the second predetermined temperature; wherein the second fluid circuit is configured for delivering an insulating fluid to provide a constant mold temperature.

5. The manufacturing method according to claim 3 or 4, characterized in that the first working fluid is water vapor or high-temperature water, the second working fluid is cooling water, the temperature of the first working fluid is higher than the first predetermined temperature, and the temperature of the second working fluid is lower than the second predetermined temperature.

6. The manufacturing method according to any one of claims 3 to 5, wherein the first fluid circuit comprises a plurality of first fluid channels arranged parallel to each other, wherein a first pitch between adjacent first fluid channels is in the range of 35-60mm, the first distance is in the range of 8-25mm, and each first fluid channel has a first diameter in the range of 5-20mm, respectively; and is

The second fluid circuit includes a plurality of second fluid passages arranged in parallel with each other, wherein a second interval between adjacent second fluid passages is 50-70mm, each of the second fluid passages has a second diameter of 20-30mm, respectively, and the first distance is smaller than the second distance, and the second fluid circuits are spaced in parallel with each other at a distance of 15-30mm from the first fluid circuits.

7. The method of manufacturing of claim 6, wherein four to eight first fluid channels are connected in parallel to form a single set of first parallel channels, and the multiple sets of first parallel channels are connected in series to form the first fluid circuit; and/or

Four to eight second fluid channels are connected in parallel to form a single set of second parallel channels, and multiple sets of second parallel channels are connected in series to form the second fluid circuit, or the second fluid circuit is formed by a plurality of second fluid channels in series.

8. The method according to any one of claims 3 to 7, wherein in step 1), the polycarbonate is plasticized by heating after drying at 100 ℃ for at least 4 hours, and the temperature of the first melt is 280-320 ℃; the first melt is output to the second extruder through a nozzle to be mixed with the fiber, the temperature of the nozzle is 290 ℃ and 300 ℃, and the temperature distribution of a barrel in the second extruder is as follows: the front section is 280 plus 290 ℃, the middle section is 270 plus 280 ℃ and the rear section is 250 plus 260 ℃; in step 3), the first predetermined temperature is at least 130 ℃ and the second predetermined temperature is at least 80 ℃.

9. The method of manufacturing of claim 2, wherein the feedstock comprises a polycarbonate and acrylonitrile butadiene styrene blend, and the temperature control device comprises a die temperature machine; in the step 1), the polycarbonate and acrylonitrile-butadiene-styrene blend is heated and plasticized after being dried for 4 hours at 80 ℃, and the temperature of the first melt is 240-270 ℃; the first melt is output to the second extruder through a nozzle to mix with the fibers, the temperature of the nozzle is 255-: the front section is 230-240 ℃, the middle section is 225-235 ℃ and the rear section is 220-230 ℃; in step 3), the mold temperature machine is configured to set the mold temperature to 60-100 ℃.

10. The method of manufacturing according to any one of claims 1 to 9, wherein the weight percentage of polycarbonate or polycarbonate and acrylonitrile-butadiene-styrene blend in the structural component is 60 to 90%.

11. The manufacturing method according to any one of claims 1 to 10, wherein the fibers are selected from glass fibers, carbon fibers, aramid fibers, natural fibers or a combination thereof, wherein the fibers have a length of 15 to 35 mm.

12. A manufacturing method according to any one of claims 1-11, characterised in that the weight percentage of fibres in the structural component is 10-40%.

13. The manufacturing method according to any one of claims 1 to 12, wherein in step 2) the pre-formed blank is conveyed on a conveyor belt with a heat-insulated heating cover and the heat-insulated heating cover is configured to be closed so that the pre-formed blank is kept at the heat-insulated temperature.

14. A structural component, characterized in that it is manufactured using the manufacturing method according to any one of claims 1-13.

15. The structural component of claim 14, wherein the structural component is an upper housing of an electric vehicle battery pack.