WO2012136142A1

WO2012136142A1 - Feeder apparatus using residual heat from material inlet/outlet of second-order screw extruder for preheating feed fiber

Info

Publication number: WO2012136142A1
Application number: PCT/CN2012/073559
Authority: WO
Inventors: 李良光; 蒋鼎丰
Original assignee: 福建海源自动化机械股份有限公司
Priority date: 2011-04-08
Filing date: 2012-04-06
Publication date: 2012-10-11
Also published as: CN102179915A

Abstract

Feeder apparatus using residual heat from a material inlet/outlet of a second-order screw extruder for preheating a feed fiber, for use in extrusion molding of a direct in-line long fiber reinforced thermoplastic composite material. A molten material extruded from an extrusion die (11) of a first-order screw extruder (1) and cut fibers formed by cutting a continuous fiber via a cutting roller are both fed into a material inlet (31) of the second-order screw extruder (3). The apparatus is characterized in that: the feeder apparatus is a blower rectifier preheating feeder tube (6) arranged under the fiber cutting roller (7), the feeder tube is passed through the material inlet (31) of the second-order screw extruder (3), the extrusion die (11) of the first-order screw extruder (1) is in communication with the feeder tube (6), and residual heat from the second-order screw extruder (3) is discharged into the feeder tube (6). The apparatus has the advantages of: lowered investment by obviating the need for an electric preheating roller apparatus, energy conservation by utilizing fully the residual heat, rapid fiber moisture evaporation by convective thermal contact between hot air and the fiber, simplified technique, reduced occurrence of a "bridging" phenomenon, facilitated mixture of the fiber and the molten material, and thus improved product strength and quality.

Description

Feeding device for preheating feed fiber with waste heat of inlet and outlet of second-stage screw extruder

The invention relates to the field of composite material processing, and is an extrusion molding of a fiber-reinforced thermoplastic composite material, in particular to a feeding device for preheating a feed fiber by using a second-stage screw extruder inlet and outlet.

LFT (Long Fiber reinforced Thermoplastics, long fiber reinforced thermoplastics, are known as long fibers compared to fibers used in conventional fiber reinforced thermoplastics. Typically, the fiber length in a fiber reinforced thermoplastic material is less than 1 mm, while in LFT, the fiber length is generally greater than 2 mm, and even the fiber length in the LFT can be maintained above 5 mm.

LFT-D-ILC is called long fiber reinforced thermoplastic material direct in-line compounding process technology (Long Fiber reinforced Thermoplastics-Direct processing-In Line Compounding). The application of LFT in automobiles is growing rapidly. Apart from the economic attractiveness, their main advantage is the flexibility in which materials can be compounded. Continuously variable fiber content, different types of fibers, plus engineering plastics open up potential applications.

The direct in-line fiber compounding system is integrated in the molding process, and the second-order screw extruder is usually used, that is, the two-screw extruder cooperates to complete the extrusion molding process.

The thermoplastic pellets or powders and other auxiliaries are first added from the hopper of the first-stage screw extruder, plasticized by the screw, and the plasticized molten polymer is squeezed from the extrusion die of the first-stage screw extruder. Exit and enter the feed port of the second stage screw extruder.

Before the fibers are mixed into the feed port of the second-stage screw extruder, the fibers are usually heated. Generally, the twisted continuous fibers are spread out with a fork and heated by several consecutive hot rolls of the heating device. Then, it is taken up into the feed port of the second-stage screw extruder.

The molding compound which is sheared and compounded by the second-stage extruder is conveyed to a pressing (or injection) molding apparatus, whereby the apparatus performs the molding work of the LFT-D-ECM or LFT-D-IM process.

Heating the fiber is one of the key steps in the overall compounding process, although the use of heating equipment increases the investment cost, but without heating it will have a more significant negative impact.

First, the heating can remove the moisture in the fiber, thereby avoiding its entry into the melt and affecting the quality of the product. Secondly, a large amount of cold fiber not preheated into the melt causes a sudden drop in the melt temperature, resulting in an increase in viscosity, not only The plasticizing effect is poor, and it is not conducive to uniform mixing and sufficient wetting; again, the melt becomes thick and thick, and the fiber is easily broken under the rotary extrusion shearing action of the screw, which affects the final mechanical strength and quality of the product. However, it is inevitable that the traditional hot roll heating equipment is bulky, energy-intensive, and costly, but it is troubled by the industry because it cannot be exempted from this necessary process.

The technical problem to be solved by the present invention is to provide a feeding device for preheating the feed fiber by using the second-stage screw extruder into and out of the feed port, thereby eliminating or reducing the use of the conventional heating device, thereby greatly reducing the energy consumption cost.

The technical solution adopted by the present invention to solve the above technical problems is: a blanking device for preheating the feed fiber by using a second-stage screw extruder into and out of the feed port for extrusion molding of the direct online long fiber reinforced thermoplastic composite material The chopped fibers extruded from the extrusion die of the first-stage screw extruder and the chopped fibers formed by cutting the continuous fibers through the chopping rolls are all fed into the feed port of the second-stage screw extruder, wherein The unloading device is an unwinding rectification preheating cutting pipe, disposed under the fiber chopping roller, the unloading pipe is introduced into the feeding port of the second-stage screw extruder, and the first step is The extrusion die of the screw extruder communicates with the blanking pipe, and the residual heat of the second-stage screw extruder includes the waste heat of the first-stage screw extruder extrusion melt and the second-stage screw extruder feed port The residual heat of the body is discharged into the blanking pipe.

The invention fully and concentratedly utilizes the waste heat emitted by the first-stage screw extruder to extrude the melt and the waste heat emitted from the feed port of the second-stage screw extruder, and generates an upward hot air flow through a customized air-rectifying and discharging pipe. Convective thermal contact with the cut-off fiber stream not only allows rapid evaporation of the moisture of the fiber, but also allows the fiber temperature to approach the melt temperature for preheating in a very short period of time.

Based on the above solution, the first-stage and second-stage screw extruders may be a single-screw extruder or a twin-screw extruder. However, with a twin-screw extruder, the performance of each part of the mixture is more uniform than that of a single-screw extruder.

Based on the above solution, the air-conditioning rectification preheating feeding pipe is connected to a channel for supplementing hot air in the middle.

The height of the channel that supplements the hot air is close to the feed port of the second stage screw extruder.

The heat source through the passage that supplements the hot air is a hot air blower.

The hot air direction of the hot air passage is the tangential direction of the rotating updraft in the unwinding preheating discharge pipe.

In this way, by supplementing the passage of the hot air, the external hot air source is used to provide hot air to further dry and heat to cut off the falling fiber flow to achieve the optimum process state.

The beneficial effects of the invention are:

1. No need for complicated and special electric preheating roller device, thus reducing investment;

2, make full use of waste heat, the external hot air source only serves as an auxiliary heat source, does not require a special power source for high power, saving energy;

3, hot air and fiber convective thermal contact, heat exchange is sufficient, fiber moisture evaporation is fast, preheating is sufficient;

4. Reduced production processes and simplified production processes;

5, due to the hot air flow to the fiber, the fiber is not easy to produce "bridge" phenomenon;

6. Since the preheating is sufficient, the fibers are more easily mixed with the melt, and the dispersibility, the fracture resistance and the wettability are greatly improved, and the strength and quality of the product are also improved.

DRAWINGS

FIG. 1 is a schematic structural view of Embodiment 1 of the present invention.

Figure 2 is a schematic view of the structure of a preferred embodiment of the present invention.

Figure 3 is a cross-sectional view taken along line A-A of Figure 2;

Description of the numbers in the drawings

1-first-stage screw extruder 11-extrusion die

2-melt

3-second stage screw extruder 31-feed port 32-double screw

4-continuous fiber 5-chopped fiber

6-Unloading pipe 7-fiber short cutting roller

8-heat source 9-channel to supplement hot air

detailed description

Embodiment 1, please refer to FIG. 1 is a schematic view showing the structure of the present invention, a feeding device for preheating the feed fiber by using a second-stage screw extruder into and out of the feed port for direct online long fiber reinforced thermoplastic composite material. Extrusion molding, the melt 2 extruded from the extrusion die 11 of the first-stage screw extruder 1 and the chopped fibers 5 formed by cutting the continuous fibers 4 by the fiber chopping rolls 7 enter the second-stage screw extrusion The feed port 31 of the outlet 3 is extruded in the second-stage screw extruder 3 via a twin-screw 31, wherein the unloading device is an air-extracting and preheating blanking pipe 6, which is disposed on the fiber Below the chopping roller 7, the blanking pipe 6 is passed into the feed port 31 of the second-stage screw extruder 3, and the extrusion die 11 and the discharge pipe of the first-stage screw extruder 1 are 6 communicating, the residual heat of the first-stage screw extruder extruding the melt 2 and the residual heat of the second-stage screw extruder feed port 31 are discharged into the blanking pipe 6, and the chopped fiber 5 is subjected to Preheat.

For a preferred embodiment, referring to FIG. 2 and FIG. 3, a channel 9 for supplementing hot air is added on the basis of Embodiment 1, which is connected to the blower of the wind blower, and the preheating of the feed pipe 6 is close to the feed port of the second-stage screw extruder. At 31, the heat source through the passage 9 that supplements the hot air is a hot air blower. The direction of the hot air entering the hot air passage 9 is the tangential direction of the rotating updraft in the unwinding preheating discharge pipe. The rest is the same as in the first embodiment.

Claims

The utility model relates to a feeding device for preheating a feed fiber by using a second-stage screw extruder into and out of a feed port for the direct extrusion of a long-fiber reinforced thermoplastic composite material, from the first-stage screw extruder (1) The chopped fibers (2) extruded from the extrusion die (11) and the chopped fibers (5) formed by cutting the continuous fibers (4) through the chopping rolls are all fed into the feed port of the second-stage screw extruder (3) ( 31), characterized in that: the unloading device is an unwinding rectification preheating discharge pipe, which is disposed under the fiber chopping roller (7), and the unloading pipe is connected to the second-stage screw extruder (3) at the feed port (31), and the extrusion die (11) of the first-stage screw extruder (1) is in communication with the discharge pipe, and the waste heat of the second-stage screw extruder is discharged into the Inside the cutting pipe.
The unloading device for preheating the feed fiber with the waste heat of the second-stage screw extruder according to claim 1, wherein the first-stage screw extruder (1) and the second-stage screw are used. The extruder (3) is a single screw extruder or a twin screw (32) extruder.
The unloading device for preheating the feed fiber with the waste heat of the inlet and outlet of the second-stage screw extruder according to claim 1, wherein the drafting and rectifying preheating cutting pipe is connected with a passage for supplementing the hot air ( 9).
The unloading device for preheating the feed fiber with the second-stage screw extruder inlet and outlet, according to claim 3, characterized in that the height of the passage (9) for supplementing the hot air is close to that of the second-stage screw extruder Feed port (31).
The unloading device for preheating the feed fiber with the waste heat of the second-stage screw extruder according to claim 3, wherein the heat source (8) passing through the passage (9) for supplementing the hot air is a kind Hot air blower.
The unloading device for preheating the feed fiber with the waste heat of the inlet and outlet of the second-stage screw extruder according to claim 3, wherein the hot air direction of the hot air passage is a rotation rise in the unwinding preheating discharge pipe The tangential direction of the airflow.