DE69722920T2 - METHOD AND DEVICE FOR MOLDING PLASTIC - Google Patents

Description

The invention relates to a shaping process, that feeding of plastic in a spray chamber with the help of a feed device has at least one conical stator and at least one has conical rotor, as well as the pressing of the plastic into a shape determined by an injection mold.

The invention also relates to a device for molding plastic, which is a spray chamber has a feed device for feeding plastic into the Spray chamber, wherein the feed device at least one stator and at least one rotatable rotor and a pressing device for Pressing the plastic fed into the injection chamber into an injection mold, to give the plastic a shape through the injection mold.

The invention further relates to a molded plastic product.

The DE 38 14 571 discloses a piston injection molding machine. This injection molding machine has a plasticizing screw in which the material to be molded is plasticized and with which it is fed to a container via a valve. The container has a piston connected to it, which can be moved with an actuator, so that the material is shaped with the aid of the piston if the container contains a sufficient amount of the material to be molded. The device is cumbersome due to its non-concentrated structure. In addition, it is difficult to adjust the device, which is therefore not suitable for the production of complex technical products. In addition, the mass to be injected is rather inhomogeneous.

WO 85/03027 discloses an injection press, in which a screw is arranged in a cylindrical body. The too melting material is fed to a feed hopper and with a screw conveyor with the feed hopper the cavity between the screw and the cylindrical body fed. The worm is rotatable, the worm thread being the one to be melted Material forward transported and conveys new raw material from the hopper. Further are thermal resistances around the body arranged around so that the raw material by the action of the thermal resistors and the heat generated by friction melts when the screw transports the material forward. simultaneously with the rotation of the worm, it also moves backwards, whereby melted mass fills the space in front of the snail's head. If a sufficient amount of material to the front of the screw the screw is stopped and the screw is stopped is pushed forward which causes the molten raw material to pass through a spray orifice the form flows. this device is quite large and therefore due to the screw length expensive. In addition, the quantities of material injected at once are pretty small. Also the orientation in the material of the material to be sprayed The product cannot be determined in any way.

WO 93/19923 discloses an injection press, which is a cylindrical body with an axially movable and rotatably mounted cylindrical screw having. The one to be introduced Material is fed into the area around the screw with a feed hopper filled. The snail, and parts of the body, have threads with which the material to be fed to the front part the injection press can be moved. The inside of the snail has a core that allows adjustment of the volume of the container, into which the material to be sprayed is transported. If the container contains a sufficient amount of the material to be sprayed the material using the screw or a combination of The screw and the core are pressed through a nozzle into the injection mold. This device is complicated and therefore difficult and expensive to manufacture. Also increased the length the screw and the core the manufacturing cost of the device. Also the orientation in the material of the product to be sprayed cannot be controlled in any way with this device.

The US 4,519,976 discloses an injection press with a conical rotor, outside of which there is a conical stator, so that the rotor, as it rotates, feeds the material to be molded to the injection chamber. The EP 0,619,172 discloses an apparatus for molding plastic having an injection chamber and a feeder for feeding the plastic into the injection chamber. The feed device has a rotatable conical rotor and a conical stator outside the rotor. The device also has a pressing device for pressing the plastic supplied to the injection chamber into an injection mold in order to give the plastic a shape determined by the injection mold. The conical structure creates an injection press with a short and simple structure, whereas it is very difficult in the injection molding machines according to the above-mentioned documents to arrange the heating and / or cooling functions of the material in such a way that they come from inside the cone formed by the feed device, ie take place by the rotating rotor. In addition, it is difficult to create high injection pressures on the molded part in the feed opening between the rotor and the stator described in the documents. In addition, it is not possible to produce stretched products with the structure according to the European publication, and the arrangement according to the US publication requires the use of complicated and cumbersome molding tools.

The object of the present invention is to provide a method and a device which do not have the above disadvantages. Another object of the invention is to provide a fibrous to create stretched plastic product that is manufactured with an injection mold.

The method according to the invention is characterized by providing a delivery device that has at least an inner conical stator and an outer conical stator and at least one rotatable, outside of the inner conical stator arranged rotor.

Furthermore, the device according to the invention is thereby characterized in that the feed device has at least one inner conical stator and an outer conical Stator and at least one rotatable, outside of the inner conical Has stator arranged rotor.

This is further through the method according to the invention manufactured plastic product characterized in that the Material of the plastic product is essentially stretched.

The main idea of the invention is that the device for supplying material into the spray chamber includes a conical rotor and a conical stator that are arranged so that the rotatable rotor is outside of the stator. The idea of one embodiment is that there is another stator that is outside of the rotatable rotor is arranged so that the material to be molded is both inside as well as outside of the rotor flows. The idea of a preferred embodiment is that a Piston into the mold with the material supplied to the spray chamber pushed is arranged in the center of the device. The thought of one another preferred embodiment is that a mandrel is arranged in the piston, whereby the material to be fed between the rotor and the stators in an essentially tubular space is filled between the mandrel and the housing, and that is outside of the mandrel is a cylindrical piston with which the pressing material is formed. The idea of a third preferred embodiment is that in the middle of the device for material supply a blower to press the material with the help of compressed air into the the injection mold is arranged certain shape.

The invention has the advantage that when feeding material with conical stators and a rotor the injection press can have a short and simple structure. If the rotor is outside the stator is arranged, the device for controlling the Temperature of the material to be molded slightly in the middle of the injection press be arranged to the material to be molded from the inner To heat the stator out. It is also easy to use the feed device for feeding the material to be formed in the inner stator so that the Injection press has a simple and compact structure. If another stator outside of the rotor is provided, the material to be molded can be brought to it will flow both inside and outside the rotor so that the rotor so to speak floats in the mass to be molded, and high injection pressures can on the molding are advantageously generated. In addition, by positioning the mandrel in the piston, the orientation of the material to be filled in, with the help the stators and the rotor are formed, are maintained, when the material is in the substantially tubular space between the mandrel and the housing is introduced. Orientation can also be maintained be by the product with a substantially tubular piston is molded, thereby producing fiber-stretched injection molded products become.

The invention is in the pending Drawings in more detail described.

Show it:

1 is a schematic side view of the cross section of a device according to the invention;

2 is a schematic side view of the cross section of a second device according to the invention;

3 is a schematic side view of the cross section of a third device according to the invention;

4 is a schematic side view of the cross section of a fourth device according to the invention; and

5 is a schematic side view of the cross section of a fifth device according to the invention.

1 shows a device consisting of a conical stator and a conical rotor rotatably provided outside the stator 2 consists. The rotor 2 is using a motor 4 turned. The speed of the cone can be with a gear 3 can be set. The speed of the rotor 2 can without the gear 3 can be set, for example by using an electric motor with an adjustable rotational frequency such as the motor 4 , In addition, it is not necessary to change the rotational frequency of the rotor 2 set, but this can be set to an appropriate level. The motor 4 can also be, for example, a hydraulic motor or another device suitable for this purpose. The material to be injected becomes the space between the rotor 2 and the stator 1 via a feed channel 5 fed. The material to be filled is filled with a filling device 6 into the feed channel 5 filled. The feed channel 5 can be easily through the fixed stator 1 be positioned so that the structure of the device is simple and compact.

The surfaces of the rotor 2 and / or the stator 1 , which abut each other, have screw threads, which are not shown in the accompanying drawing for the sake of clarity. The rotor guides with the help of these screw threads 2 at its rotation of a spray chamber 7 the material to be injected. The spray chamber 7 is cylindrical. If the spray chamber 7 a sufficient amount of the material to be injected, a cylindrical piston presses 8th the material in the middle of the injection press through a nozzle 10 , The piston 8th is operated with an actuator, such as. B. an engine 9 who in 1 is shown schematically. Instead of the hydraulic motor 9 the actuator can also be, for example, a spindle motor or another construction known per se. In connection with the nozzle 10 a shape is arranged into which the material to be injected is directed. This form is not shown in the attached figure for the sake of clarity.

The stator is very light and easy 1 with one device 11 to control the temperature of the material to be injected, the device being used for effectively heating and / or cooling the material to be injected from the inside.

2 shows a further device according to the invention. The reference numerals in 2 correspond to those in 1 , Outside the rotor 2 there is a conical outer stator 12 , The material to be injected is then both inside and outside the rotor 2 the spray chamber 7 fed. The rotor 2 thus floats in the material to be molded, so that it is possible to generate high injection pressures on the molded part in a fairly simple manner.

The material to be injected is fed through the feed channels 5 inside and outside of the rotor 2 brought in. Via the first feed channel 5 the material to be injected can cover the space between the rotor 2 and the outer stator 12 are fed. The material to be fed is filled with a first filling device 6 , which can be, for example, a screw conveyor, a pump or another filling device known per se, is filled into the first feed channel. Via the second feed channel 5 the material to be molded is made through openings provided in the rotor 13 the space between the rotor 2 and the inner stator 1 fed. The material to be molded is filled with a second filling device 6 that of the first filling device 6 corresponds to the second feed channel 5 filled. A single feed channel is also conceivable, the material to be molded along the individual feed channel in a manner known per se, both on the inside and on the outside of the rotor 2 can be supplied.

Inside and outside of the rotor 2 have screw threads, which are not shown in the accompanying drawing for the sake of clarity. The rotor guides with the screw thread 2 during its rotation of a spray chamber 7 the material to be injected. The spray chamber 7 is cylindrical and is from the inner surface of the outer stator 12 limited. If the spray chamber 7 contains a sufficient amount of the material to be injected, a cylindrical piston presses 8th the material in the middle of the injection press through a nozzle 10 , In connection with the nozzle 10 an injection mold is arranged into which the material to be injected is directed. This shape is in the adjacent 2 not shown for the sake of clarity.

3 shows a third device according to the invention. The reference numerals in 3 correspond to those in 1 and 2 , The piston 8th is hollow, creating a cylindrical mandrel 14 is arranged in it so that the spray chamber 7 is formed by a substantially tubular space formed by the mandrel 14 and the outer stator 12 is limited. The definition "substantially tubular" in connection with the present invention includes, for example, alternatives in which the spray chamber 7 has an elliptical or asymmetrical cross section or the size or shape of the cross section varies. The spray chamber 7 is constructed in such a way that that of the stators 1 and 12 and the rotor 2 fed material into the spray chamber 11 flows while doing it from the stators 1 and 12 and the rotor 2 maintained spiral orientation. A locking device 15 , which prevents the material to be injected from flowing into the mold too early, is provided at the end of the spray chamber. The locking device is during the spraying process 15 opened so that the material to be molded when the hollow cylindrical piston moves 8th from the spray chamber 7 into the injection mold 16 can be pressed. The nozzle 10 The device is circular, so that the orientation of the material to be molded is also in the injection mold 16 can be maintained. There are also no cast seams in the with the injection mold 16 provided product. The injection mold is for the sake of clarity 16 only shown schematically and their shape can be chosen freely. The adjacent one 3 schematically shows a shape 16 which, for example, supplies elbows for pipes.

4 shows a fourth device according to the invention. The reference numerals in 4 correspond to those in 1 to 3 , At least the outer surface of the inner stator 1 is after the end of the rotor 2 cylindrical. At a corresponding point is at least the inner surface of the outer stator 12 cylindrical. The spray chamber 7 is thus formed in the space between the outer stator 12 and the inner stator 1 is at the end of the rotor 2 starts and with the nozzle 10 at the end of the outer stator 12 and the inner stator 1 ends. If the rotor 2 rotates, it transports the plastic to be molded into the spray chamber 7 , The rotor provides the radial orientation of the plastic fibers, the orientation being maintained in the material when it is in the substantially tubular spray chamber 7 is transported. If more material with the rotor 2 the new material pushes the old material out of the nozzle 10 , Outside the nozzle 10 the moldings close 16a and 16b which can be moved in the manner shown by the arrows A so that they are the plastic to be molded 18 surround or move away from it. If a sufficient amount of the plastic to be molded 18 out of the nozzle 10 was pressed out, the mold halves 16a and 16b close to the plastic to be molded 18 emotional. Then using a blower 17 air under high positive pressure into the interior of the plastic to be molded 18 blown so that this positive pressure the plastic to be molded 18 against the walls of the from the mold halves 16a and 16b formed injection mold presses, whereby the object gets its final shape. The orientation of the fibers in the plastic to be molded 18 also remains essentially unchanged. The blower 17 is arranged so that there is air between the stators 1 and 12 and the rotor 2 by blows.

5 shows a fifth device according to the invention. The reference numerals in 5 correspond to those in the 1 to 4 , For the sake of clarity, the feed channels and the filling devices are not shown. A mold core 14 is an extension of the inner stator 1 intended. In this case, a substantially tubular spray chamber 7 between the mandrel 14 and the outer stator 12 educated. The mold core 14 is provided with an extension cone, and the outer stator 12 is provided with a similar shape in the appropriate place, so that the diameter of the spray chamber 7 increases on the extension cone. The material to be molded is thus provided with an axial orientation while it flows into the spray chamber at the orientation cone. The material to be molded is made with an essentially tubular piston 8th the same way as in 3 is shown in the form 16 pressed to obtain stretched plastic molded products. The mold core 14 can, if desired, with the help of the rotating device 20 turn to provide radial orientation. If it is not necessary that the mandrel 14 rotates, it can be used together with the inner stator 1 be formed in a fixed construction.

5 shows grooves 19 that are on the outer surfaces of the inner stator 1 and the rotor 2 are provided. The surfaces of the rotor and the stator which are in contact with one another are preferably provided on one side with a screw thread and on the other side with counter-grooves, the direction of which is opposite to the screw thread and which is smaller than the grooves of the screw thread and smaller Have slope so that the counter grooves are closer to each other than the grooves of the screw thread. The surfaces of the rotor and the stator, which abut one another, particularly preferably have a screw thread on one side and an essentially direct groove on the other side, ie a groove with a pitch of 90 °, so that this direct groove prevents the forward movement of the material to be molded improved during normal operation. On the other hand, the rotor 2 can still be rotated continuously when the forward movement of the material at the end of the spray, for example through the piston 8th is prevented because the material to be molded can flow back into the device along the longitudinal grooves and the material pressure cannot rise too high near the ejection side of the device. In this way, the rapid production of small objects, for example, is made possible when the rotor 2 spins at a constant speed at all times. In addition, this type of groove construction in a conical arrangement is very advantageous since the material to be molded cannot be destroyed, since the return path of the material in the feed zone is short and it passes the grooves with the shape of the screw thread.

The device from 5 is also with a networking device 21 with which the material to be molded first crosslinks and then with the piston 8th in the form 16 can be pressed. Therefore, the device is particularly suitable for the production of objects from cross-linked polyethylene and injection molded products made of this material. The networking device 21 can either in the longitudinal section of the inner stator 1 or be arranged along the extension cone. In the in 5 The situation shown is the material to be molded in the spray chamber 7 supplied at a temperature which is below the crosslinking temperature of the material, and the crosslinking agent is reacted by the temperature of the material by means of the crosslinking device 21 is increased.

Then the material is made with an essentially tubular piston 18 in the form 16 pressed. It is therefore possible to manufacture injection molded products with permanent orientation that have been effectively consolidated by crosslinking. With the device according to the invention it is also possible to produce multi-layer injection molded products, in which case different materials on different sides of the rotor 2 are fed and both layers of material into the injection mold at the same time 16 be pressed. The different layers can also have different degrees of orientation, for example by different temperatures for the materials on the different sides of the rotor 2 be maintained, or by being on one side of the rotor 2 Polyethylene is fed and polyethylene and peroxide are fed on the other side, so that the peroxide crosslinks one side, which therefore remains stretched, and the other side is essentially not stretched. Such a piece can be used, for example, as a connecting sleeve, one surface of which is welded onto the surface of the object to be joined.

The drawings and the associated description are only intended to illustrate the inventive idea. The details of the invention may vary within the scope of the claims. Therefore, the surfaces of the outer stator 12 and the inner stator 1 , only the one on the rotor 2 adjacent surfaces, either a conical, cylindrical or other shape, for example depending on the needs of manufacturing technology or other requirements. In addition, more than one rotor and more than two stators can be provided, as a result of which it is possible to supply material to the spraying chamber in several layers and thereby to provide multi-layer products.

Claims (22)

Molding process, which involves the supply of a plastic mass in a spray chamber ( 7 ), with a feed device that has at least one conical stator and at least one rotor, and the pressing of the plastic into an injection mold ( 16 . 16a . 16b ) certain shape, characterized in that a feed device has at least one inner conical stator ( 1 ) and an outer conical stator ( 12 ) and at least one rotatable, outside the inner conical stator ( 1 ) arranged rotor ( 2 ) having. A method according to claim 1, characterized in that the mass with the aid of a spray device of a substantially tubular spray chamber ( 7 ) is supplied. A method according to claim 1 or 2, characterized in that the rotor ( 2 ) different masses are supplied to produce a multi-layer injection molding, and that both layers in the mold ( 16 ) are pressed. A method according to claim 2, characterized in that the mass in the spray chamber ( 7 ) networked and then into the mold with the help of an essentially tubular piston ( 16 ) is pressed. Method according to one of claims 1 to 3, characterized in that at least the outer surface of the inner stator ( 1 ) after the end of the rotor ( 2 ) is cylindrical and that at a corresponding point at least the inner surface of the outer stator ( 12 ) is cylindrical, whereupon the inner stator ( 1 ) and the outer stator ( 12 ) an essentially tubular spray chamber ( 7 ) so that the rotor ( 2 ) while rotating the spray chamber ( 7 ) Feeds mass and at the same time pushes mass out of the spray chamber, and that an injection mold ( 16a . 16b ) surrounds the mass and air is passed through the interior of the plastic mass to be molded, whereupon the plastic mass to be molded with overpressure against the walls of the injection mold ( 16a . 16b ) is pressed. A method according to claim 5; characterized, that the air between the feeder of the plastic mass is passed through into the plastic mass to be molded. Method according to claim 2, 3 or 4, characterized in that the plastic mass via an annular nozzle ( 10 ) into the injection mold ( 16 ) is injected. Method according to one of claims 1, 2, 3, 4 or 7, characterized in that the plastic mass from the spray chamber ( 7 ) with a piston arranged in the middle of the feed device of the plastic mass ( 8th ) into the injection mold ( 16 ) is pressed. A method according to claim 7, characterized in that the nozzle ( 10 ) when feeding plastic mass into the spray chamber ( 7 ) with a locking device ( 15 ) is closed and before the plastic mass is pressed out into the injection mold ( 16 ) is opened again. Plastic molding device with a spray chamber ( 7 ), a feed device for feeding a plastic mass into the spray chamber ( 7 ), the feed device having at least one stator ( 1 ) and at least one rotatable rotor ( 2 ) and a pressing device for pressing the spray chamber ( 7 ) plastic mass fed into an injection mold ( 16 . 16a . 16b ) to the plastic mass through the injection mold ( 16 . 16a . 16b ) to give specific shape, characterized in that the feed device has an inner conical stator ( 1 ) and an outer conical stator ( 12 ) and at least one rotatable, outside the inner conical stator ( 1 ) arranged rotor ( 2 ) having. Apparatus according to claim 10, characterized in that the at least one rotor ( 2 ) and the inner and outer stator ( 1 . 12 ) have common grooves and counter-grooves, including grooves in the at least one rotor ( 2 ) with a first inclination and grooves in at least one of the stators ( 1 . 12 ) with a second inclination, to facilitate the advance of the plastic mass to the spray chamber ( 7 ) and to allow the flow of the plastic mass in the opposite direction from the spray chamber ( 7 ) away if the forward movement is prevented. Apparatus according to claim 10 or 11, there characterized in that the spray chamber ( 7 ) is essentially tubular. Device according to claim 12, characterized in that the device comprises a networking device ( 21 ) for cross-linking the plastic mass as well as an essentially tubular piston ( 8th ) for pressing the mass into the injection mold ( 16 ) having. Device according to one of claims 10 to 12, characterized in that at least the outer surface of the inner stator ( 1 ) after the end of the rotor ( 2 ) is cylindrical, and that at a corresponding point at least the inner surface of the outer stator ( 12 ). is cylindrical, whereupon the inner stator ( 1 ) and the outer stator ( 12 ) an essentially tubular spray chamber ( 7 ) and that the device is a blower ( 17 ) for blowing air into the interior of the plastic mass to be molded, so that the plastic mass to be molded with positive pressure against the walls of the injection mold ( 16a . 16b ) is pressed. Device according to claim 14, characterized in that the blower ( 17 ) is arranged in the middle of the feed device of the plastic mass. Device according to one of claims 10 to 13, characterized in that a piston ( 8th ), which is designed so that it fits into the injection mold ( 16 ) Compressed mass to be sprayed, is arranged in the middle of the feed device of the plastic mass. Device according to claim 12 , characterized in that the nozzle ( 10 ) the device through which the plastic mass is injected into the injection mold ( 16 ) is sprayed, is ring-shaped. Device according to claim 17, characterized in that a closing device ( 15 ) to close and open the nozzle ( 10 ) together with the nozzle ( 10 ) is arranged. Injection molded product, characterized in that the material of the plastic product is essentially stretched is. Plastic product according to claim 19, characterized in that that the plastic product is made without cast seams. Plastic product according to claim 19 or 20, characterized characterized that the plastic product is at least two different Has layers that were pressed into the injection mold at the same time. Plastic product according to claim 21, characterized in that that the different layers with different degrees of stretching are provided.