DE2337789A1 - INJECTION MOLDING MACHINE - Google Patents

Description

9141-73 / Kö / s
Case L 9
Convention Date:
July 25, 1973

Chloride Lorival Limited, Little Lever, Near Bolton, Lancashire,

England

Injection molding machine

The invention relates to an injection molding machine for manufacture of hollow objects made of thermoplastic materials with a shape in the matrix of which a male mold forms the Mold cavity protrudes, and with an adjusting device for mutual adjustment of the mutually facing surfaces of the Die and the male part located inside the die with a protruding and a female adjusting member from which one is provided on the male part and the other on the female part with the formation of interacting adjustment surfaces, and with a device that in the course of the casting process the one Adjusting member moves relative to the other.

The invention is related to the manufacture of articles such as Parts of ballpoint pens can be used, but mainly for the manufacture of thermoplastic vessels for electric batteries thought. For these purposes, the shape of the machine has a lower die or a die into which an upper die or a The male part protrudes from one or more male part plates to form the mold cavity. Especially for injection molding of Thin-walled moldings may require a high pressure, and the patrix plates can move so far that considerable Fluctuations in wall thickness occur. XJm this difficulty

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To remedy the problem, various methods were used to adjust and hold the opposing surfaces of the patrix and the die in their mutual position in the area of the bottom of the mold cavity. For example, you can go to this Purpose to provide interlocking members, namely a protruding and a receiving member, one of which is to the one and the other is arranged on the other of the two surfaces. Of course, it arises at the point where the two links are in contact with each other, a hole in the wall of the shaped object. It was therefore proposed to set up a facility provide that one of the two members withdraws relative to the other in the course of the molding process.

An injection molding machine of the type mentioned at the beginning is according to the invention characterized in that the one adjusting member as an injection nozzle for injecting the thermoplastic material into the Shape is formed and that the one adjusting device displacing this adjusting member during injection the main amount of the thermoplastic material in an effective suit, in which the adjustment surfaces only through a small gap, which is considerable is narrower than the wall thickness of the object to be molded, are spaced from each other, and during the injection of the remaining amount of the thermoplastic material in a retracted position, in which the adjustment surfaces one of the wall thickness of the to be molded Object have a comparable distance, such that the wall thickness is fully formed in the area between the adjustment surfaces can be.

According to one embodiment of the invention, the device is to move the one setting surface relative to the other set up so that they the relevant setting surface during a short initial time of injection in a withdrawn position, so that the space between the adjustment surfaces can be filled with thermoplastic material, holds and then in their effective position advances and injects the bulk of the thermoplastic; materials in this position.

The two adjustment surfaces are expediently parallel

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Faces which, when brought together, the adjustment members were locked against movement and have one or more grooves through which the thermoplastic material then also flow could when the adjustment surfaces are in contact with each other.

Preferably, the adjustment surfaces are arranged around the nozzle outlet so that the thermoplastic material emerging from the nozzle flows over them into the mold cavity. For example the adjustment surfaces can be two parts of frustoconical surfaces which surround the nozzle concentrically.

When injection molding thin-walled hollow bodies, it is always a problem to ensure that the thermoplastic material all Areas of the mold cavity and that where there is a certain point of more than one. Approaching, the two of them Material flows flow into each other and combine in such a way that no weak point remains. In a known injection molding machine of the type mentioned, the molding compound enters the area of the adjustment surfaces when they are in engagement with one another, whereby, as mentioned above, a hole remains in the wall of the molded article. Then the adjustment surfaces are apart lifted off, so that a gap remains between them, which should be filled with material or molding compound from the neighborhood. Man notes, however, that this material no longer flows properly into one another, especially if it is already to a considerable extent has cooled down. By using one of the setting members as a spray nozzle for injection, it can be ensured that the material additionally pressed in to fill the hole in the wall of the object is a fresh material in the hot State, whereby the weak points that have occurred so far are reduced or eliminated.

While the invention is not limited to any particular theory of mechanism of action; however, it is believed that the narrow space between the facing setting surfaces is filled with a layer of molding compound, which because of its small thickness is easily cooled by the two opposing setting surfaces, so that a different

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-A-

Relatively stiff buffer forms by means of which the male part is fixed in position with respect to the female part. This assumption is made by supported the experiment, with the setting mandrels or dowels held in the advanced position during the entire molding process will. When taking the molding out of the press, it turns out that the hole in the bottom is about 0.15 mm * (0.006 inch) thick skin is spanned. It has been shown that test moldings produced in this way are leak-tight.

When the bulk of the molding compound has been injected and the pressure exerted by it can then be reduced, the two mutually facing surfaces are lifted from one another, so that fresh, hot thermoplastic material flows into and through the gap between them, with the thin layer already there mixed and the wall thickness supplemented so that it is comparable to that of the rest of the object. The short initial injection with one setting surface retracted ensures that the gap between the setting surfaces is filled with thermoplastic material and that this material is pressed out when the setting surfaces are brought into their operative position.

Apart from that, it is achieved in any case that the patrix can be correctly adjusted in terms of position with respect to the die, although the adjustment surfaces are never in direct contact with one another come, although a perfect adjustment is not obtained without such adjustment surfaces.

Preferably, for molding a hollow object with an undivided interior space or a vessel for a multicellular one electric battery for the object as a whole or for each cell of the vessel, one projecting and one receiving Adjustment member and a single nozzle are provided, which is located at a point corresponding to the bottom center of the object or the cell are arranged.

In a special embodiment, this is an adjusting member in the direction of the separation of the two molded parts back-

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draggable.

In this case, this adjusting member can also serve as an ejector or lifter for the molded object and three have different positions: an effective position, in which there is a small gap from the other actuator when the form is closed one back is separated for the purpose of adjusting the position of the male part drawn position in which it is separated from the other actuator by a considerably larger gap, so that the thermoplastic material can add to the wall thickness; and an advanced position in which there is the finished molded article with the mold open the patrix lifts off. In this case, each setting member serving as an ejector is expediently arranged in the male part of the mold, while the spray nozzle is arranged in the die part.

The following are specific embodiments of the invention For example, explained on the basis of the drawing. Show it:

Figure 1 is a schematic representation of the bottom of an inventive shaped battery jar, seen in plan with respect to the finished battery, but in elevation in the direction of arrow 1 in Figure 2 with regard to the location of the battery during of form j

FIG. 2 shows a schematic sectional illustration of a mold for shaping the battery vessel

Figures 3 and 4 enlarged sectional views of parts of Figure 2, the end of a male mold and the interacting with it Show part of the die in two different positions;

FIG. 5 shows an illustration of the end of the male mold, seen in the direction of arrow 5 in FIGS. 3 and 4J

FIG. 6 shows a representation corresponding to FIG. 4 of a modified one Construction; and

Figures 7, 8, 9 and 10 are schematic representations of the shape seen in the direction of arrow 7 in Figure 2, with illustration successive stages of the molding process when using the Adjusting links as ejectors.

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In the embodiment illustrated in FIGS becomes the injection molding machine or apparatus for molding a Battery jar 10 with six cells separated by thin partitions 11 are used. The form can be made in the usual way from a lower die or a die 12, which forms a single mold cavity for the entire battery vessel, into which an upper die or a male part 15 with six separate male part plates 16, between which there are narrow gaps 17 for the formation of the partition walls, protrudes. In addition, each male plate can in its End face have narrow notches or slots for the formation of mud ribs 18.

According to the invention, each male plate is provided with an adjustment device provided, which connects its end face with an adjacent point in the die, in the form of a dowel or wedge-acting adjusting member in connection with a spray nozzle for injecting the plastic compound of the battery jar. That Adjustment member consists of a protruding and a receiving adjustment surface, one of which is on the male plate and the other is provided on the die and one of which is retractable and one of which contains the spray nozzle. Figure 3 4 and 4 show an arrangement in which the female adjustment surface is provided on the male plate and is retractable and the protruding adjustment surface is provided on the female and forms the spray nozzle. If desired, however, can also be used instead the protruding adjustment surface is provided on the male plate, the protruding adjustment surface be retractable or the receiving adjustment surface form the spray nozzle or any Combination of these arrangements can be used. The arrangement shown, in which the adjustment surface is retractable in the male plate has the advantage that it can be used as an ejector, as will be explained later. The arrangement shown, in which the receiving adjustment surface is provided on the male plate is also provides a simple arrangement in which the recess in the bottom of the molded vessel shaped button is on the inner surface of the vessel between the mud ribs, where it does not interfere.

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Therefore, as shown in FIGS. 3 and 4, each male plate 16 has an ejector pin 20 which penetrates a central bore of the plate in the longitudinal direction. The lifting pin has a frustoconical recess 21 at its end, which forms the receiving adjustment surface, as well as two radial grooves 22 with a U-profile, which run from the frustoconical recess radially outward to the circumferential surface of the lifting pin 20. In contrast to the frusto-conical recess 21 has the die a corresponding frusto-conical projection 25, as shown in Figure 3, "the recess 21 0.15 now fitted in the upper part with a narrow margin 30 of, for example (6/1000 inch).

In the middle of the frustoconical projection 25 * of the Forms protruding adjustment surface, there is the spray nozzle 26, through which the thermoplastic material for the molding of the relevant Cell of the battery jar is injected. The digging pen 20 is provided with a device (not shown), synchronized with the injection unit, for withdrawing from the circuit shown in FIG provided operating position shown in an inoperative position shown in Figure 4 during the molding process. As described later, it can be advanced further into an ejection or lever position.

In operation, the mold is closed, with the lifting pin assuming the retracted position shown in FIG. 4, in which it is The end is flush with the end face of the male plate 16. He remains in this position for a short preliminary stage during the one small amount of thermoplastic material is injected through the spray nozzle 26 and through the gap 28 between the facing frustoconical adjustment surfaces, as indicated by the arrow 29 indicated, and flows out through the radial grooves 22. The thermoplastic material thus fills the gap between the end of the Lifting pin 20 and the surface of the die, in particular of the frustoconical projection 25

The lifting pin is then pushed into the operating position shown in Figure 3, so that most of the thermoplastic material in the Gap 28 is pressed out and only a thin layer in the tight clearance

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space gap 30 remains. This layer can be about 0.38 mm (I5 / IOOO inches) thick, and it is believed to be because of this small thickness, the thermoplastic material from the mutually facing surfaces of the male mold and the female mold is rapidly cooled or is quenched, so that a relatively rigid buffer is formed, whereby the male part is firmly adjusted with respect to the female part while most of the thermoplastic material is injected through the radial grooves 22 into the mold cavity. As can be seen from the drawing, these grooves are aligned along the long dimension of each cell to allow the flow of the thermoplastic material to facilitate after the removed parts of the vessel ^ if desired, however, other arrangements or a other number of these grooves can be used.

The main part of the injection takes place with the margins for wall thicknesses kept firmly at the desired values.

When the injection is almost complete, the lifting pin 20 is retracted from the operating position shown in FIG. 3 into the inoperative position shown in FIG. 4, in which its end is flush with the end face of the male mold plate 16. The thermoplastic material now entering the mold cavity from the injection nozzle 26 can flow freely through the gap 28 between the mutually facing frustoconical adjustment surfaces, as indicated by the arrow 29, and it is even almost forced to flow over these surfaces where previously a thinned area has been in the bottom of the formed vessel.

In this way, the weak point that might otherwise occur in the bottom of the vessel can be eliminated and replaced at this point Wall part are generated that is as strong as any other part of the vessel wall. This is done by using an adjuster Combined spray nozzle achieved, since the area occupied by the adjustment surfaces is no longer a blind end for the Represents entry of the thermoplastic material. It has been found that with other arrangements where a retracted adjustment member leaves an empty cavity that must be filled with thermoplastic material from a more distant spray nozzle, which

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flowing and a blind end or an opposing flow of material The material found may not connect properly, so that a weak point can arise in the bottom wall.

The initial formation of a full skin or Membrane by means of the clearance 30 reduces the risk of a poor seal in the finished vessel. It also enlarges thereby the allowable tolerance when setting up or adjusting the mold.

As mentioned above, the adjustment member attached to the male plate may be the protruding one and the one provided in the female die Adjustment member form the receiving adjustment surface. Such an arrangement is shown in Figure 6, but in this case the receiving adjustment surface 31 is provided on a projection 32 of the die and the male plate in its end face a has a slightly larger recess 33 from which the protruding adjustment surface 34 protrudes. Thus, the one shown in FIG. 6 is behind driven position the end of the lifting pin in the same plane as the not recessed part of the end face of the patrix plate. The mode of operation is analogous to that of the arrangement according to FIGS. 3 and 4 and therefore does not need to be explained in detail here.

The arrangement according to FIG. 6, like that according to FIGS. 3 and 4, has the advantage that the one formed by the receiving adjustment surface 31 Button from the outer surface of the vessel bottom does not protrude further than the surrounding surface and that the only protrusion formed one formed by the recess 33 on the inner surface of the bottom wall Ring projection is. The arrangement according to FIG. 6 has the further advantage that the wall thickness is essentially at all points is uniform.

Figure 7 to 10 illustrate the manner in which the Aushebestift except that it forms one of the regulating faces, can also be used to 20, the molded casting of the male parts stand out plates.

Figure 7 shows the mold in the fully closed position, in

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that the molding takes place, as already described. The side wall portion of the die is comprised of four sections 41, which can be pulled away from the ground and from each other to the vessel to release, which in its outer wall comprising a number of sub-sections. FIG. 8 shows the mold during opening, but with the sections 41 held closed so that they grip the undercuts and partially pull or strip off the molding from the male mold. Then, as shown in FIG. 9, the sections 41 are peeled off from one another or opened so that they reveal the molding which remains loosely on the male part. Finally, as shown in Figures 9 and 10, the lifting pins 20 are advanced further so that they lift the molding from the male parts and the molding falls down as shown in Figure 10, actuating a microswitch (not shown), causing the press is automatically set for a new molding process.

If one compares FIG. 7 with FIG. 8, one sees that in both Figures the sections 41 remain closed so that their projections 6l engaging in the undercuts 62 of the molded article Hold the molding in the die. It is therefore not the patrix only removed from the die or the die, but also from the molding, so that the molding does not hang or hang on the patrix sticks. Up to now it has been customary to remove the molding or the molded part from the male or female part by means of a stripping plate deduct. This stripping plate acts on the vessel during the retraction of the male or female dies via a relatively small area around the vessel mouth or orifice with pressure, what under certain circumstances, especially when pressure is introduced into the vessel, can lead to the vessel being deformed, for example bulged, when it is ejected or lifted off or is bulging out.

In the present method, on the other hand, the vessel is fully supported, and in addition to its upper edge, any other horizontal outer surfaces with hold-down members, ribs, etc., provide that the stripping force is distributed more evenly. As soon as the male parts part by about three quarters of their length from the shaped vessel are pulled out, the parts of the die move

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-limit the same speed as the patrix forwards and sideways so that they reveal the outer shape of the vessel. That The vessel remains loosely on the end of the male plate, from where it is lifted off by means of the lifting pins.

The arrangement described above enables the vessel to be lifted from the mold at higher temperatures, since it is at Taking off can be less easily deformed. For this reason, the shaped piece can be ejected in the mold after a shorter cooling time so that the product output of the machine per unit of time increases.

Molds for creating vessels or containers with the usual outer retention parts require the use of a split die as an essential feature. When using this part Pieces as a device for stripping or pulling off the vessel from the patrix eliminate the costs normally associated with such Tools or machines used stripper plate.

In the absence of a stripper plate, it will also possible to arrange the male molds closer to the relevant surface of the molding, thereby reducing the inclination of the male molds plates for spreading is reduced during the molding process.

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Claims (11)

2337783 1 9 Claims Injection molding machine for the production of hollow articles from thermoplastic materials with a mold in their Die a male part protrudes to form the mold cavity, as well as with an adjustment device for mutual adjustment of the mutually facing surfaces of the die base and the male part located inside the die with a protruding one and a female adjustment member, one of which to form cooperating adjustment surfaces Male and the other is provided on the female mold, and with a device that in the course of the casting process the one adjusting member compared to the other shifts, thereby characterized in that the one adjusting member as an injection nozzle for injecting the thermoplastic material into the mold is formed and that the one adjusting device displacing this adjusting member during the injection of the Main amount of the thermoplastic material in an effective suit, in which the adjustment surfaces are only through a small gap, which is considerably narrower is than the wall thickness of the object to be molded, are spaced from each other, and during the injection of the remaining amount of the Thermoplastic material holds in a retracted position in which the adjustment surfaces one of the wall thickness of the object to be molded have a comparable distance so that the wall thickness in the area between the adjustment surfaces can be fully formed. 2. Injection molding machine according to claim 1, characterized in that that the one adjustment surface in relation to the other displacing device this adjustment surface during a short initial period of injection in a retracted position so that the space between the adjustment surfaces Can be filled with thermoplastic material, holds and then advances into its effective position and for the purpose of injection of the Most of the thermoplastic material holds in this position. 3. Injection molding machine according to claim 1 or 2, characterized 309886/0970 characterized in that the two adjustment surfaces are parallel surfaces which, when brought together, the adjustment members would lock against movement and have one or more grooves through which the thermoplastic material could flow even if the adjustment surfaces were in contact with each other. 4 · Injection molding machine according to one of the preceding claims, characterized in that the adjustment surfaces are arranged around the nozzle outlet, such that emerging from the spray nozzle thermoplastic material through them into the Mold cavity flows. 5. Injection molding machine according to one of the preceding claims, characterized in that the adjustment surfaces Approximate parts of the frustoconical surfaces that concentrically surround the spray nozzle. 6. Injection molding machine according to one of the preceding claims for molding a hollow object with an undivided interior, characterized in that a single protruding and a single female adjusting member and a single spray nozzle is provided which is located at a location corresponding to the center of the bottom of the object to be molded are arranged. 7. Injection molding machine according to one of claims 1 to 5 for molding a vessel for a multi-cell electric battery, characterized in that for each cell a single protruding and a single female adjusting member and a single injection nozzle positioned at a position corresponding to the center of the bottom of the cell are. 8. Injection molding machine according to claim 5 or 6, characterized characterized in that the one adjusting member is retractable in the direction of the separation of the two mold parts. 309886/0970 9. Injection molding machine according to claim 8, characterized in that the retractable adjusting member also serves as an ejector for the shaped object and has three layers: an effective position in which it is through a small gap is separated from the other adjusting member when the mold is closed for the purpose of adjusting the position of the male part; one withdrawn position in which it is separated from the other adjusting member by a gap of considerable dimensions, so that the thermoplastic material can add to the wall thickness; and an advanced one Position in which it lifts the molded object from the patrix when the mold is open. 10. Injection molding machine according to claim 9 _}, characterized in that each setting member serving as an ejector is arranged in the male part of the mold and that the spray nozzle is arranged in the female part. 11. Injection molding machine according to claim 9 or 10 for producing a molding with undercuts in its side walls, characterized et gekennzeichn that the die part Contains pieces that can be removed from one another in the direction transverse to the main direction of the separation of the male and female molds, derar ^ that they can be peeled off the undercut parts of the molding; andthat a device is provided which the male mold a certain distance from the die with portions of the same held closed while holding the molding in the Retracting the die and eliminating any adhesion between the molding and the male die, then pulling the sections away from each other, so that they release the molding, pull the patrix further from the die and finally extend the ejector adjusting member, in such a way that that the molding is repelled by the male mold. 309886/0970