JP2005335394A - Injection molding apparatus for plastic molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding apparatus capable of raising the output of finished molded articles and reliably restraining a parting face that should not be opened even in the case of the use of a conventional injection molding machine. <P>SOLUTION: The injection molding apparatus for a plastic molded article comprises an injection molding machine (1) and its attachment tool (2). The tool (2) has at least two cavities (11, 12) corresponding to the dimension of the molded article to be manufactured. The tool (2) consists of at least three members (4, 5, 6) movable each other. At least one passage (13) to supply melting plastic is prepared in these members. A restraint system movable between two positions is mounted on the members (4, 5, 6) of the tool (2). By the restraint system, an intermediate member (5) and a front member (4) having an inlet (14) of the passage (13) exclusively from the tool (2) are mutually constrained in a first position, and the intermediate member (5) and a rear member (6) exclusively from the tool (2) are mutually constrained in a second position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is an apparatus for injection molding a molded body made of plastic, comprising an injection molding machine and a tool belonging to the machine, wherein the tool has at least two cavities that match the dimensions of the molded body to be manufactured, The tool consists of at least three parts in which the tool can move relative to each other, and these parts are fixed to each other in a working position along separating surfaces extending perpendicularly to the direction of movement of these parts through the cavity and parallel to each other. , Each separation surface extends through at least one cavity, and at least one passage is provided in the tool for supplying molten plastic, this passage ends on the one hand on the cavity and on the other hand on the tool surface. It relates to the one that ends and is connected to the injection molding machine at the operating position.

Such a device is described in the German magazine “Plastic 84” (1994) 10, Seiten 1375-1382.
Injection molding machines are used to produce molded bodies with almost any shape. The attached tool need only have a cavity through which molten plastic can be poured. The part of the tool that is separated by the separation surface is firmly compressed in the operating position, for example by hydraulic pressure. After injecting the plastic into the cavity, the prior art keeps the tool closed until the compact in the cavity has cooled sufficiently so that it becomes solid and can be removed from the tool. . As a result, the tool is opened on the separating surface and the parts are moved away from each other. During the time that the molded plastic cools in the cavity, the injection molding machine is not used. This disadvantage is particularly significant when trying to produce relatively thick-walled shaped bodies with long cooling times.

  When a tool operating in tandem technology is used in accordance with the German magazine "Plastic 84" first mentioned, the efficiency of the injection molding machine is increased. In an injection molding machine operating with such a tool, the part of the tool is opened alternately on two separating surfaces. During the cooling time of the molded body on the first separation surface, the molded body can be removed from the second separation surface. This method of operation is advantageous for shaped bodies having a cooling time longer than the dispensing time required for filling the cavities. Injection molding machines that operate in tandem technology are expensive special machines. This injection molding machine requires a movable intermediate plate provided at an intermediate position, and an injection device is connected to the intermediate plate from the side. The molten plastic is injected into each cavity through a passage provided in the intermediate plate. This known tandem technique is not used with conventional injection molding machines or only after extensive modifications.

  The problem that forms the basis of the present invention is that, even when using a conventional injection molding machine, by reliably restraining the separation surface that should not be opened, the yield of the finished molded body can be increased. The first type of device is to be constructed.

  In order to solve this problem, according to the present invention, a passage is provided in the tool from the entry point to the first separation surface and further to the second separation surface, and a partial passage extending from this passage to the cavity is provided. The tool part is provided with a restraining device which can be moved between two positions, whereby the restraining device restrains only the middle part of the tool and the front part with the entrance of the passage in the first position. In the second position, only the middle part and the rear part of the tool are constrained to each other.

  This device can be used for conventional commercial injection molding machines without modification and special additional means. The simple tool used so far with only two parts separated by one separation surface need only be replaced by a new tool consisting of three parts with two separation surfaces. As in the tandem technique described above, this tool increases the production yield, during which the plastic injected into the cavity of the other separation surface cools while the molded body protrudes in the region of one separation surface. The restraining device used for the part of the tool during each cooling stage is important for this injection molding device. This restraining device is easily movable between two positions. While the two parts of the tool are constrained to each other under the same residual forces that are tightly combined when the compact is cooled by the restraining device, the separating surface for the third part is used for the projection of the finished compact. Can be opened at the same time. Subsequently, after closing the separating surface and injecting plastic into the cavity, the restraining device is brought into the second position with the tool still closed. In that case both parts of the tool with the newly filled cavity remain in close contact with each other, while the previously constrained separation surfaces project the cooled compact during the injection, If the pressing force acting on the tool during the forming process is released, it can now be opened.

  Regarding the configuration of the restraint device, in order to solve the above-described problem, according to the present invention, at least one drive device having at least one slider extending in the direction of the axis of the tool is provided in the middle portion of the tool. The slider is movable between the two end positions in the longitudinal direction in two opposite directions, and the tool is further provided with at least one clamping device in the area of each separating surface, the clamping device A first part is provided in the middle part of the tool and a second part cooperating with the first part is attached on the one hand to the front part of the tool and on the other hand to the rear part, When at least one holding body extending in the direction of the axis of the tool is attached to the front part and the rear part of the tool as the second part of the clamping device and the tool is closed One end of the holding body enters into the corresponding first part of the clamping device, at least one clamping body is provided at one end, and the slider is used for restraining operation of the clamping body at each one of its end positions. Fit into the corresponding clamping device.

  This restraining device is particularly simple. Basically this consists of a drive device with a slider and two clamping devices, with the sliders snapping into these clamping devices alternately. In order to effectively constrain each of the two parts of the tool, it is only necessary to push the slider into one of the clamping devices by means of the drive device in the appropriate closed position and move the clamping body of the clamping device to the restraining position. . At each restraining position, the slider is pulled out of the clamping device in the area of the other separation surface, so that the tool can be opened at this separation surface.

  The drive can advantageously be operated automatically. This can be done by a drive device that operates pneumatically or electrically. However, a hydraulic drive is used as much as possible.

  A restraining device consisting of a drive device with a slider and a clamping device can be advantageously accommodated in a tool contour, saving space. Thus, the outer dimensions of the tool are not increased by the restraining device part. Depending on the size of the tool, at least two restraining devices can advantageously be provided on the two opposite sides of the tool.

  An embodiment of the invention is shown in the drawing.

  Only the portions of the injection molding apparatus necessary for understanding the invention are shown in the drawings. Elements which are known in principle, such as opening / closing mechanisms or cooling passages or heating devices, are not shown. 4 to 7, the hatched portions are not hatched for the sake of clarity.

  The injection molding apparatus according to FIG. 1 comprises an injection molding machine 1 and a tool 2 connectable thereto. The injection molding machine 1 may be a conventional commercially available machine without a special device. This is movable in the direction of the double arrow 3.

  The tool 2 consists of three parts: a front part 4, an intermediate part 5 and a rear part 6. This tool has a rear part 6 coupled to a pressing plate 7, which is connected to a pressure generator 8. For example, an air pressure or a hydraulic press can be used as the pressure generator 8. The three parts of the tool 2 are separated from each other by two separating surfaces 9 and 10 extending parallel to each other. Each separating surface 9 and 10 can have at least one cavity 11 or 12 of the tool 2, the inner dimensions of which correspond to the geometric shape of the molding to be produced. In the illustrated embodiment, two cavities 11 and 12 are entered for each separation surface 9 or 10.

  In the illustrated embodiment, a passage 13 is provided in the center of the tool 2 to help supply molten plastic to the cavities 11 and 12. The passage 13 begins at the entrance 14 which is on the surface of the tool 2 and opens outward. This passage first extends in the front part 4 of the tool 2 to the separation surface 9 and then further to the separation surface 10 in the middle part 5 of the tool 2. In order for the plastic material called sprue to be easily removed from the passage 13 after cooling and protruding of the molded body, the passage 13 is conically formed in both parts as shown. Partial passages 15 and 16 exit from the passage 13 and lead to the cavities 11 and 12. The partial passages 15 and 16 are preferably on the separating surfaces 9 and 10.

  The device according to the invention is shown in the operating position in FIG. This operates, for example, as follows.

  The three parts 4, 5 and 6 of the tool 2 are firmly in contact with each other in the operating position. These parts are compressed by a pressure generator 8 and pressed against a fixed holding plate 17 which serves as a fixing device, and a front portion 4 of the tool 2 is provided on this holding plate. In order to produce a molded body in the cavities 11 and 12, the injection molding machine 1 is brought close to the tool 2 to the entrance 14 of the passage 13. The molten plastic present in the injection molding machine 1 can then be pushed into the passage 13. The plastic fills the cavities 11 and 12 via the passage 13 and the partial passages 15 and 16. When the cavities 11 and 12 are filled using sufficient pressure, the injection molding machine 1 is closed. The plastic present in the tool 2 is then cooled.

  After a sufficient cooling time, the tool 2 is opened, for example at the separation surface 9. The portions 5 and 6 remain constrained to each other by a restraining device described later. These parts can be brought into a position that can be seen from FIG. 2 together with the pressing plate 7 that is movably supported after the pressing force generated by the pressure generator 8 is interrupted. The restraining device is then advantageously configured in such a way that a residual force is maintained that brings together both parts 5 and 6 of the tool 2 after the pressing force of the pressure generator 8 has disappeared. The molded body produced in the cavity 11 can now be removed from the tool 2. The sprue remaining in the passage 13 of the front part 4 of the tool 2 is removed, for example by compressed air, so that this part of the passage 13 is emptied again.

  The tool 2 is then brought back to the closed or operating position which can be seen from FIG. 1, in which the parts 4, 5 and 6 are compressed firmly by the pressure generator 8. The cavity 11 is again filled with plastic. Subsequently, the restraining device is operated so that the parts 5 and 4 of the tool 2 are restrained together as described above for the parts 5 and 6. The tool 2 is then opened at the separating surface 10 and only its rear part 6 is moved by the pressing plate 7 to a position which can be seen from FIG. The completed compact in the cavity 12 can now be removed. During this time, the plastic in the cavity 11 of the separation surface 9 cools. The sprue in the part of the passage 13 in the intermediate part 5 is removed again, for example by using compressed air.

  The tool 2 is then brought back to its closed or operating position according to FIG. The cavity 12 is again filled with plastic and the parts 5 and 6 are restrained together. Meanwhile, the molded body in the cavity 11 is cooled, so that the tool 2 can be opened at the separating surface 9 as described above. Thus, the cavities 11 and 12 are always filled with plastic alternately and protrude after cooling.

  Due to the cooling of the plastic in the cavities 11 and 12, as already explained, it is necessary for the two parts of the tool 2 to remain restrained after the disappearance of the pressing force applied to the pressing plate 8, respectively. Therefore, in accordance with FIGS. 4-7, a restraining device that is present on at least one side of the tool 2 but is present on at least two different sides is used to maintain the residual force. Its structure and operation will be described below.

  According to the schematic diagram of FIG. 4 in which the tool 2 of the device is shown in partly closed or operating position, the restraining device comprises a drive device 19 with a substantially rod-shaped slider 18 and a two-part and broken line. And two clamping devices K surrounded by. The slider 18 extends in the direction of the axis of the tool 2. The slider is movable in this direction between two end positions. A holding body 20 or 21 extending in the direction of the axis of the tool 2 belongs to each tightening device K as a first part. The holding body 20 is attached to the front part 4 of the tool 2, and the holding body 21 is attached to the rear part 6. Installed.

  As the second part of the clamping device K, stoppers 22, 23 and 24, 25 are attached to the intermediate part 5 of the tool 2 in the range of the separating surfaces 9 and 10, respectively. There is at least one stopper for each clamping device K. The distance between the stoppers corresponds to the width of the holding body 20 or 21 respectively, and the holding body fits into the corresponding second part, that is, the stopper of the clamping device K at the respective restraining position of the tool part as the first part, At that time, it is pushed between both stoppers. Each holding body 20 or 21 has two clamping bodies R at its free end (so that there is at least one clamping body R), these clamping bodies intersecting the longitudinal direction of the respective holding body. A holding body is also provided so as to be movable.

  The fastening body R is configured as a roller as much as possible, and can be freely rotated, and is provided on each holding body 20 or 21 so as to be able to move laterally across the axial direction of the tool 2. However, the clamping body is in the non-operating position, as shown for the holding body 20 on the right side of FIG. 4, is within the outline of the holding body and is moved outward by the slider 18 and in the restraining position of the tool 2 in FIG. As shown with respect to the left side of the holder 21 and the stoppers 24 and 25, they engage with the stoppers.

  The slider 18 is movable between two end positions in the direction of a double arrow 26, i.e. in opposite directions. At one end position shown in FIG. 4, the slider 18 is fitted into the clamping device K within the range of the separation surface 10, so that the intermediate portion 5 and the rear portion 6 of the tool 2 are restrained from each other. For this reason, as already described, the slider 18 pushes the roller R sideways from the holding body 21, so that the roller R comes behind the stoppers 24 and 25. Since the roller R is supported by the holding body 21 so as to be freely rotatable and movable to the side, the holding body 20 without the slider 18 is provided between the rollers R when the holding body 21 is pulled out from the stoppers 24 and 25. As indicated by, the stopper is again moved to its inoperative position in the respective holding body.

  The joint action of the tightening device K and the slider 18 will be described with reference to FIGS.

  The holding body 20 has a slit-like recess 27 extending in the longitudinal direction and provided at the center at an end portion used for fitting into the clamping device K, and the slider 18 is located at the constraining position of the clamping device K. Get stuck in 27. In the illustrated embodiment, the recess 27 opens outward at two points opposite each other. At this point, the two fastening bodies R configured as rollers are freely rotatable and are provided so as to be movable across the longitudinal direction of the holding body 20. For this reason, the tightening body has circular recesses on its end face, and pins 28 attached to the holding body 20 are fitted in these recesses. In the drawing, the upper roller is within the outline of the holding body 20 and can therefore pass by the stopper 22. Since the lower roller is pushed out from the holding body 20 by the slider 18 shown by a broken line, it is in a restrained position after the stopper 23.

  Each holding body 20 or 21 essentially requires only one clamping body R. In that case, only one stopper is required for each part 5 of the intermediate tool 2. However, for reasons of symmetry, the above-described embodiments with two clamping bodies R and two corresponding stops, respectively, are advantageous. The clamping body R can also have a different geometric shape with respect to the shape of the roller described above.

  In a preferred embodiment, two separate clamping devices K are provided on each side of the tool 2 as shown in FIG. 5 for one side of the tool 2. Thereby, unintentional opening of the tool 2 on the separating surfaces 9 and 10 during the restraint phase is prevented with high safety. In this embodiment, the drive device 19 comprises two sliders 18, which are attached to a common carrier 29 and are therefore moved simultaneously by the drive device 19.

  The restraint device described above starts, for example, as follows, starting from the operating position of the device according to FIG.

  Before the pressure generator 8 is shut off, both parts 5 and 6 of the tool 2 are constrained to each other according to FIG. Therefore, both sliders 18 are pushed between the rollers R of both holding bodies 21 by the driving device 19. The parts 5 and 6 of the tool 2 are thereby brought together with a sufficient residual force after the pressure generator 8 has been shut off. Due to the protrusion of the shaped body in the cavity 11, the tool 2 can now be opened at the separation surface 9 as shown in FIG.

  After protruding from the cavity 11, the tool 2 is closed again and plastic is again injected into the cavity 11 when the pressure generator 8 is operating. Before the cavity 12 of the separating surface 10 is removed, the restraining device for the front part 4 and the intermediate part 5 of the tool 2 is activated. Therefore, the driving device 19 moves the slider 18 to another end position, and the slider 18 pushes the roller R of the holding body 20 outward at this position, so that the roller comes behind the stoppers 22 and 23. When the separating surface 10 is opened simultaneously, this restraining position of the tool 2 can be seen from FIG. 7 as in FIG.

  Fig. 2 shows a schematic cutaway view of a device according to the invention in a closed position.   Fig. 2 shows the open position of the device according to Fig. 1;   2 shows different open positions of the device according to FIG.   The restraint device which can be used in the device is shown in principle view.   An embodiment of the replenished apparatus is shown with respect to FIG.   The device according to FIG. 5 is shown in an open position corresponding to FIG.   The device according to FIG. 5 is shown in an open position corresponding to FIG.   The holding body used in an apparatus is shown with an enlarged view.   Fig. 9 shows a cross section taken along line IX-IX in Fig. 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection molding machine 2 Tool 4 Front part 5 Middle part 6 Rear part 8 Pressure generators 9 and 10 Separation surface 11 and 12 Cavity 13 Passage 14 Entrance location 15 and 16 Partial passage 18 Slider 19 Driving device 20 and 21 Holding body K Tightening Device R Fastening body

Claims (6)

An apparatus for injection molding of a molded body made of plastic, comprising an injection molding machine and a tool belonging to the machine, wherein the tool has at least two cavities corresponding to the dimensions of the molded body to be manufactured, and the tool is in relative motion Consisting of at least three possible parts, these parts fixedly abutting each other in a working position along separation surfaces extending through the cavity at right angles to the direction of movement of these parts and parallel to each other; Each separation surface extends through at least one cavity, and at least one passage is provided in the tool for supplying molten plastic, this passage ends on the one hand on the cavity and on the other end on the entry point on the surface of the tool, In the operating position where the entry point is connected to the injection molding machine,
A passage (13) is provided in the tool (2) from the entry point (14) to the first separation surface (9) and further to the second separation surface (10), from which the cavity (11, 12) Partial passages (15, 16) that reach up to
The part (4, 5, 6) of the tool (2) is provided with a restraining device movable between two positions, by means of this restraining device, the middle part (5) of the tool (2) at the first position. ) And the front part (4) having the entrance (14) of the passage (13) are restrained from each other, and in the second position, only the middle part (5) and the rear part (6) of the tool (2) A device characterized by being constrained. An apparatus for injection molding of a molded body made of plastic, comprising an injection molding machine and a tool belonging to the machine, wherein the tool has at least two cavities corresponding to the dimensions of the molded body to be manufactured, and the tool is in relative motion Comprising at least three possible parts, namely a front part, a middle part and a rear part, fixedly abutting each other by the action of a pressure generator along separating surfaces extending parallel to each other in the operating position, and at least supplying molten plastic One passage is provided in the tool, this passage ends on the one hand in the cavity and on the other end in the entry point on the surface of the tool, and in the operating position the entry point is connected to the injection molding machine and the tool part has two A restraint device movable between the end positions is provided, and when the pressure generating device is shut off at the first end position by the restraint device, the middle part of the tool And only the front portion having an inlet point of the passage is constrained to one another, in a second end position, in which the intermediate portion and a rear portion of the tool is constrained to one another,
At least one drive device (19) having at least one slider (18) extending in the direction of the axis of the tool (2) is provided in the intermediate part (5) of the tool (2), and the slider (19) (19) is movable in two opposite directions in the longitudinal direction between the two end positions,
The tool (2) is further provided with at least one clamping device (K) in the range of the respective separation surfaces (9, 10), each first part of this clamping device being an intermediate part of the tool (2) A second part attached to (5) and cooperating with the first part is attached on the one hand to the front part (4) of the tool (2) and on the other hand to the rear part (6);
One holding body (20, 21) extending in the direction of the axis of the tool (2) as a second part of the clamping device (K) on the front part (4) and the rear part (6) of the tool (2) Is attached and one end of the holding body (20, 21) enters the corresponding first part of the clamping device (K) when the tool (2) is closed, at least one clamping body (R) at this end. Is provided,
A device characterized in that the slider (18) fits into the corresponding clamping device (K) at one of its end positions for the restraining operation of the clamping body (R).   The tool (2) is provided with two separate clamping devices (K) and two sliders (18) provided one above the other in the range of each separating surface (9, 10). 2. The apparatus according to 2.   At least one clamping body (R) movable across the axial direction of the tool at the end of the holding body (20, 21) that fits into the corresponding part of the clamping device (K) at the restraining position of the tool (2) ) In the restraining position, forming a first part of the respective clamping device (K) and engaging a fixed stopper (22, 23, 24) attached to the intermediate part (5) of the tool (2) Device according to claim 2 or 3, characterized in that   5. Device according to claim 4, characterized in that the clamping body (R) is configured as a roller freely rotatable about its axis.   One clamping body (R) is provided on each of the two opposite sides of the holding body (20, 21), and two corresponding stoppers (22, 23 or 24) are respectively provided in the intermediate part (5) of the tool (2). 25) is mounted. 6. Device according to claim 4 or 5, characterized in that it is mounted.

Images