CN1307032C - Method of raising quality of press shaped product and its device - Google Patents

Abstract

The invention relates to a method and a device for improving the quality of compression-molded products, wherein the polymer material or its mixture is mixed and melted by an extruder, then extruded into the inner cavity of a compression-molded mold, and then formed after being cooled. During this process, the extruder works continuously. During the process of pressing, product cooling and taking out, the continuously produced molten material is sequentially introduced into another pressing mold by the melt flow guide device, or enters the melt storage of the extruder. The melt storage and delivery device between the section or the extruder screw head and the compression molding device. After the pressed product is taken out, the stored molten material is introduced into the compression molding mold.

Description

Method and device for improving quality of press-molded products

technical field

The invention belongs to the field of polymer material forming technology and equipment, and relates to a method for improving the quality of a polymer material or its mixture by pressing and molding products, in particular to a mechanical device required for implementing the method.

Background technique

The traditional compression molding process is generally to add thermoplastic or thermosetting polymer powder or pellets to the lower mold or fixed mold cavity of the preheated or to-be-heated molding mold, and the polymer in the mold can be formed under the continuous heat. When the temperature is high, the upper mold or movable mold of the forming mold is pressed towards the polymer under the action of external force, contacts with the surface of the polymer, and stops when the polymer is pressed to a preset product thickness, after the mold is cooled or naturally cooled , In-mold polymer molding. This traditional compression molding process is intermittent. The polymer powder or pellets must be produced from the monomer after several production processes. After the powder or pellets enter the molding mold, it takes a long time to soften or even melt when heated, so that the product is formed. The cycle is longer and the production efficiency is lower.

Chinese patent CN1289287A discloses an extrusion-pressure molding method for manufacturing optical products, wherein the molten material of the optical polymer extrudate is supplied to the lower die of the die set consisting of a lower die and an upper die that moves in sequence, and then The upper mold is placed on top of the lower mold containing the molten material and the mold set is pressurized to form an optical product. After forming the optical product, the lower and upper molds are separated and recycled to form additional optical products. In this method, the lower mold of the forming mold set is conveyed in a mold shuttle, and then the upper mold of the mold set is placed on the filled lower mold to form the polymer-containing mold on the shuttle set, which is then placed under a press that pressurizes the polymer's die set with a predetermined pressure. The thickness of the formed optical product is generally determined by the pre-set cavity between the upper and lower dies. In this device, the die set is not mechanically connected to the extruder, and the die set is disassembled from the runner and the press. of.

However, according to this patent publication, the melt coming out of the extruder first comes out of the normal air environment, and the melt has a large temperature difference inside and outside the extruder, until the melt is cut off and enters the lower die for compression molding . These temperature differences will lead to a large plastic gradient inside and on the surface of the polymer material, causing uneven flow of the polymer material during the pressing process, and causing the final product to have undesirable properties such as uneven stress.

US Patent 2003/0198708A1 discloses a plastic compression molding device. This device includes an extruder, a turntable equipped with several molding dies, a turntable equipped with a device for transferring and receiving melt, etc., wherein the turntable equipped with molds rotates in opposite directions with the latter turntable, and the latter turntable receives The device for the melt is a ring, and there are several. At the beginning, one of them is close to the nozzle of the extruder to receive the extruded melt. After it is filled, it is rotated by the turntable above the mold of the former turntable and the melt is discharged into this In the mold, the mold after receiving the melt is rotated out of its original position by the former turntable, pressed and formed, and then the next ring repeats the above action, and the cycle continues. In order to avoid the temperature difference between the melt inside and outside the extruder, the latter turntable of the device is equipped with hot air insulation facilities.

However, the device disclosed in this patent is very complicated and requires two rotating disk transmission mechanisms. The extruded melt cannot reach the molding die in one step, and a melt transfer process is required in the middle.

Contents of the invention

The purpose of the present invention is to solve the problems and deficiencies of the prior art. A further object of the present invention is to simultaneously provide a technical solution for the molding of high-difficulty or large-scale polymer materials or their mixtures.

One aspect of the present invention relates to a method for making better compression-molded products of polymeric materials or mixtures thereof, and another aspect relates to a mechanical device for implementing this molding method.

The molding method involved in the present invention includes, in order, the feeding of a single polymer material or a mixture of multiple materials, melting, continuous production of molten material, and the molten material directly enters the compression molding mold from the extruder through the connecting device, and after reaching a predetermined amount , the melt flow guide device in the connecting device between the extruder and the press molding device cuts off the melt supply, and the movable mold presses against the melt until the melt reaches a predetermined thickness, then cools and forms, and then opens the mold to take out the product. In the process of pressing, product cooling and taking out, the continuously produced molten material is sequentially introduced into another pressing mold by the molten material flow guiding device.

Another advantageous method involved in the present invention is that when only one compression molding device is used, the continuously produced molten material enters the melt storage section of the extruder or the extruder screw during the compression, product cooling and removal processes. The melt storage and delivery device between the head and the compression molding device, after the pressed product is taken out, the stored molten material is introduced into the compression molding mold.

The feeding method involved in the present invention is to add a variety of materials to the feed inlet (3) of the extruder (1) after being separated or mixed in advance, or to add a polymer material or a mixture of multiple materials to the feed inlet (3), And the filling material is added from the side feed port (41) or the upper auxiliary feed port (61) of the extruder (1).

The mechanical devices involved in the present invention are: a compounding extrusion comprising an extruder, at least one compression molding device, a connecting device for introducing the molten material produced by the extruder into the compression molding device and connecting the two - Compression molding device.

The extruder involved in the present invention is a single-screw extruder, a multi-screw extruder or a twin-screw extruder, wherein the screws of the twin-screw extruder rotate in the same direction or in different directions during operation. The extruder has a feed port (3), or has a feed port (3) and a feed port (41) that can be connected to a twin-screw extrusion feeding device (not shown) or/and a feed port (41) that can be connected to a single-screw extruder Out of the feeding device (not shown) or for the upper auxiliary feeding port (61) of natural blanking. The extruder is provided with at least one opening or natural escape port (7, 8) for vacuum suction device (not shown).

The molten material flow guiding device or switch valve part of the present invention contains or allows at least one molten material to pass through, and guides the molten material into each pressing mold by rotating or moving up and down.

Description of drawings

Fig. 1 is a schematic front view of a compounding extrusion-compression molding machine equipped with only one set of compression molding dies for implementing the method involved in the present invention.

Fig. 2 is a schematic top view of a compounding extrusion-compression molding machine equipped with multiple sets of compression molding dies for implementing the method of the present invention.

Detailed ways

The polymer material compounding extrusion-compression molding method involved in the present invention and the specific implementation mode of its implementation device are described in detail with reference to the accompanying drawings as follows:

Referring to Figure 1:

The compounding extrusion-compression molding device involved in the present invention is mainly composed of a plasticizing screw extruder (1) equipped with a melt storage and delivery device (10), which can be loaded and unloaded to open and close the compression molding mold (17, 18). Device (25), the connecting device (12) that is equipped with switching valve part (13) that connects extruder (1) and compression mold (17,18) is formed.

After each device reaches the required temperature, the molding process starts, and the various materials are separated or mixed in advance and then added to the feed port (3) or a polymer material or a mixture of two or more (including two) materials is added to the feed port (3). 3) Adding, and the filler is supplemented at the upper end through a twin-screw extrusion feeding device (not shown) at the side feeding port (41) or through a single-screw extrusion feeding device (not shown) or natural feeding Feed mouth (61) adds.

Driven by the rotation of the screws (5, 9), the material continuously moves toward the tip of the screw, undergoes the process of being transported, mixed, and melted, and is vacuumed at the escape port (7) or/and (8) by a vacuum device (not shown) or natural exhaust. The fully melted molten material enters the space of the compression molding mold (17, 18) through the open connection guide pipe (12) of the switch valve (13), until the amount of molten material reaches the required amount of the product, the movable mold (18) is pressed to Melting material, stop when the melting material reaches the predetermined thickness, cool and solidify to form, and then open the mold to take out the product. In the process of pressing, product cooling and taking out, the continuously produced molten material enters the melt storage delivery section (10) of the extruder or the melt storage delivery device between the screw head of the extruder and the compression molding device (not shown in the figure) Shown), after the pressed product is taken out, the molten material that is stored and sent is introduced into the space of (17,18) in the pressing mold.

Referring to Figure 2:

After each device reaches the required temperature, the molding process starts, and the various materials are separated or mixed in advance and then added to the feed port (3) or a polymer material or a mixture of two or more (including two) materials is added to the feed port (3). 3) Adding, and the filler is supplemented at the upper end through a twin-screw extrusion feeding device (not shown) at the side feeding port (41) or through a single-screw extrusion feeding device (not shown) or natural feeding Feed mouth (61) adds.

Driven by the rotation of the screw (9), the material continuously moves towards the tip of the screw, undergoes the process of being transported, mixed, and melted, and is vacuumed at the escape port (7) or/and (8) by a vacuum device (not shown) or naturally exhaust. Enter the space of the compression molding mold (25) through the open connection guide pipe (12) of the melted material through the molten material flow guiding device (113), until the amount of molten material reaches the required amount of the product, the molten material flow guiding device ( 113) Cut off the supply of molten material, press the movable mold (18) to the molten material, stop when the molten material reaches a predetermined thickness, cool and solidify to form, and then open the mold to take out the product. In the process of pressing, product cooling and taking out, the continuously produced molten material is sequentially introduced into the space in another compression molding mold (26, 27, 28) by the molten material flow guiding device (113).

Claims (10)

1. A method for improving the quality of press-molded products, characterized in that: 1) Add the polymer material or its mixture into the feed port of the extruder, and feed the filler into the side feed port of the extruder through the twin-screw extrusion feeding device, or through the single-screw extrusion feeding device or Naturally added to the upper auxiliary feed port of the extruder, 2) The material is dispersed and mixed, plasticized and melted through the continuous operation of the extruder screw, and becomes a molten material. 3) The molten material directly enters the compression molding mold from the extruder through the connecting device. After reaching the predetermined amount, the molten material flow guide device in the connecting device between the extruder and the compression molding device cuts off the supply of molten material, and the moving mold presses toward The molten material is cooled and formed until the molten material reaches a predetermined thickness, and then the mold is opened to take out the product. 4) In the process of pressing, product cooling and taking out, the continuously produced molten material is sequentially introduced into another pressing mold by the molten material flow guiding device. 2. The method according to claim 1, characterized in that: in the process of pressing, product cooling and taking out, the molten material produced continuously enters the melt storage section of the extruder or the screw head of the extruder and presses and forms The melt storage and delivery device between the devices, after the pressed product is taken out, the stored molten material is introduced into the compression molding mold. 3. A method according to claim 1, characterized in that the press-forming mold is heated. 4. The device for implementing the method for improving the quality of press-molded products as claimed in claim 1 is characterized in that: the device comprises an extruder, at least one press-molding device, and the molten material produced by the extruder is introduced into the press-molding device And a connecting device for connecting the two: wherein, the extruder contains at least one screw, at least one feed port, and at least one exhaust port. 5. The device for improving the quality of press-molded products according to claim 4, characterized in that: there is a melt storage device or a melt storage delivery device between the extruder or the screw head of the extruder and the press-molding device. Functional section. 6. The device for improving the quality of press-molded products according to claim 4 or 5, characterized in that: the melt storage and delivery function section of the extruder is the fuselage inner diameter/screw outer diameter adjacent to the front end of the melting section Greater than or equal to fuselage inner diameter/screw outer diameter of melting section. 7. The device for improving the quality of press-molded products according to claim 4 or 5, characterized in that: the melt storage and delivery function section of the extruder is that the bottom diameter of the screw adjacent to the front end section of the melting section is less than or Equal to the bottom diameter of the screw in the melting section. 8. The device for improving the quality of press-molded products according to claim 4, characterized in that: the melt flow guiding device or the switching valve part contains at least one channel through which the melt passes or enables at least one melt to pass through. pass. 9. The device for improving the quality of press-molded products according to claim 4 or 8, characterized in that: the molten material flow guiding device or the switching valve member guides the molten material into each press-molded product by rotating and/or moving up and down. inside the mold. 10. The device for improving the quality of press-molded products according to claim 4 or 9, characterized in that: the molten material flow guiding device or the switching valve is driven by electric, pneumatic or hydraulic pressure to implement the guiding and switching action.

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