Silicone injection moulding adapter and method for injection moulding silicone workpieces

Abstract

The present invention relates to an injection moulding machine (1) with a machine frame (3), a closing unit (4) with two clamping plates (8r, 8l), an injection unit (5), an injection unit actuator (6), by means of which the injection unit (5) is movable along the machine frame (3), a tool mould (7) and a silicone injection moulding adapter (2) arranged between a tool mould half (14r) and a clamping plate (8r) for injecting silicone into the tool mould (7). The silicone injection moulding adapter (2) has an adapter body (22) and an adapter piston (23). The adapter body (22) comprises a silicone transfer chamber (29), a closable feed channel (31) via which silicone can be fed to the silicone transfer chamber (29), and an injection channel (33) via which silicone can be injected from the silicone transfer chamber (29) into the tool mould (7). The adapter piston (23) is displaceably mounted in the silicone transfer chamber (29) and, by displacing the adapter piston (22), silicone can be injected from the silicone transfer chamber (29) via the injection channel (33) into the tool mould (7). The adapter piston (23) can be inserted into the silicone transfer chamber (29) of the adapter body (22) by moving the injection unit (5) by means of the injection unit actuator (6).

Description

[0001] 12774 / 3 / 1 WO Silicone injection molded adapter

[0002] Silicone injection molding adapters and methods for injection molding of

[0003] silicone workpieces

[0004] The present invention relates in general to an injection molding machine with a machine frame, a clamping unit arranged on the machine frame with two clamping plates, an injection unit with a cylinder housing, a screw shaft movable in the cylinder housing and a plasticizing volume extending between the cylinder housing and the screw shaft, and a mold with two mold halves, each assigned to one of the clamping plates, and in particular to a silicone injection molding adapter and a method for injection molding silicone workpieces.

[0005] Such injection molding machines are typically used for injection molding conventional plastics, such as elastomers, thermosets or thermoplastics.

[0006] In this process, plastic granules are typically filled into the (screw) channels of the rotating screw shaft of the injection unit and heated to melting temperature by the rotation of the screw shaft within the cylinder housing and the resulting frictional heat, and optionally by additional heating of the cylinder housing. The volume extending between the cylinder housing and the screw shaft is called the plasticizing volume.

[0007] The flowable plastic melt now collects within the plasticizing volume in an area extending between the screw tip and the mold, since at this point an outlet through which the melt could escape from the cylinder housing is typically still closed. 12774 / 3 / 1 WO Silicone Injection Molding Adapter

[0008] Since the screw shaft is typically mounted to be axially movable, it retracts due to the pressure building up in the area of ​​the screw tip and unscrews itself from the molten plastic in a manner similar to a corkscrew, so that the flowable molten plastic accumulates between the screw tip and the mold.

[0009] The backward movement of the screw shaft is deliberately slowed down in order to build up a desired back pressure in the molten plastic.

[0010] As soon as a sufficient volume of molten plastic for the workpiece to be injected has accumulated in the plasticizing volume in front of the screw tip, the screw shaft is moved axially towards the clamping plates by means of a screw shaft actuator.

[0011] This causes the molten plastic located in the plasticizing volume in front of the screw tip to be injected (forced out) through a nozzle from the injection unit and injected through the mold half facing the injection unit into a cavity in the adjacent mold.

[0012] The molten plastic then solidifies into a solid within the mold. For thermoplastics, this typically occurs through cooling, while for thermosets and elastomers, it typically occurs through heating the molten plastic.

[0013] Subsequently, the two molds, each mounted on one of the two clamping plates, are lifted apart by the clamping unit, and the solidified plastic workpiece is removed from the mold 12774 / 3 / 1 WO silicone injection molding adapter. After this demolding, the mold closes again, and the injection molding cycle begins anew.

[0014] The injection unit, along with the cylinder housing and screw shaft, is typically movable along the machine frame relative to the clamping unit by means of an injection unit actuator. The injection unit actuator serves to press the injection unit (more precisely, the nozzle of the injection unit) against the mold half that is located on the clamping plate facing the injection unit.

[0015] The contact force transmitted from the injection unit actuator via the injection unit to the mold half must be sufficiently large to ensure that no plastic melt escapes between the injection unit and the mold half during the injection process.

[0016] The injection unit can be removed (lifted off) from the closing unit by means of the injection unit actuator, by moving (driving away) the injection unit from the closing unit.

[0017] Such injection molding machines are typically designed to process specific materials and quantities of material by adapting the geometry of the screw shaft and cylinder housing.

[0018] Recently, the production of silicone workpieces (silicone workpieces) using injection molding has become increasingly important. 12774 / 3 / 1 WO Silicone Injection Molding Adapter

[0019] However, the injection molding process for silicones differs fundamentally from the injection molding process for conventional plastics, such as thermoplastics, thermosets and elastomers.

[0020] A key difference is that silicone is fed to the injection molding machine already in a flowable (liquid) form, so it no longer needs to be melted, and that conveying the liquid silicone through an injection unit with a screw shaft, where the silicone would be heated and sheared, would lead to an undesirable deterioration of the material properties.

[0021] US patent application US 2019 210 260 Al describes an injection molding machine with an injection system and a clamping system, wherein the injection system includes a removable injection module. The injection module has all parts that come into contact with the injection material and includes a valve arrangement that can switch between a filling position for loading the injection module with material and an injection position for ejecting material from the injection module into the mold.

[0022] DE 11 2021 007 370 T5 describes an injection device that is able to inject a certain amount of resin material in each injection process, while preventing air from entering a cylinder.

[0023] Against this background, injection molding machines designed for processing thermoplastics, thermosets and / or elastomers (conventional injection molding machines) are generally unsuitable or only very poorly suited for processing silicone and manufacturing silicone workpieces. 12774 / 3 / 1 WO Silicone Injection Molding Adapter

[0024] And even if it were theoretically possible to inject silicone into a mold using a conventional injection molding machine, just like conventional plastic melts, the subsequent cleaning effort would be very high, which would make the use of a conventional injection molding machine for the production of small quantities of silicone workpieces even less attractive.

[0025] For the processing of silicone using injection molding, additional silicone injection molding machines specifically designed for this application are typically purchased, which involves relatively high costs and additional space requirements.

[0026] Against this background, the present invention aims to provide an injection molding machine of the type described above with improved practical suitability, which is designed and suitable for processing conventional plastics such as thermosets, thermoplastics and elastomers, but can also be quickly and easily converted and used for processing silicone.

[0027] This problem is solved by the injection molding machine according to claim 1, the silicone injection molding adapter according to claim 9 and the method for injection molding silicone workpieces according to claim 10.

[0028] Particularly advantageous embodiments of the invention are described in the dependent claims. The characterizing features of the advantageous embodiments implemented in connection with the injection molding machine according to the invention can, of course, also be used in the silicone injection molding adapter according to the invention (12774 / 3 / 1 WO).

[0029] silicone injection molding adapter as well as in the invention

[0030] Methods for use can be .

[0031] The injection molding machine according to the invention comprises a machine frame, a clamping unit arranged on the machine frame with two clamping plates, an injection unit with a cylinder housing, a screw shaft movable in the cylinder housing and a plasticizing volume extending between the cylinder housing and the screw shaft, an injection unit actuator by means of which the injection unit together with the cylinder housing and the screw shaft can be moved relative to the clamping unit along the machine frame, a mold with two mold halves, each of which is assigned to one of the two clamping plates, a silicone injection molding adapter arranged between one of the two mold halves and one of the two clamping plates for injecting silicone into the mold, wherein the silicone injection molding adapter has an adapter body and an adapter piston, the adapter body a silicone transfer chamber,a closable feed channel through which silicone can be supplied to the silicone transfer chamber, and an injection channel through which silicone can be injected from the silicone transfer chamber into the mold, the silicone transfer chamber being fluidically separated from the plasticizing volume of the injection unit, the adapter piston being slidably mounted in the silicone transfer chamber and allowing silicone to be injected from the silicone transfer chamber into the mold via the injection channel by moving the adapter piston, and the adapter piston being retractable into the silicone transfer chamber of the adapter body by moving the injection unit using the injection unit actuator.

[0032] The invention is based on the finding that by using a silicone injection molding adapter according to the invention, which is arranged between a mold half and one of the two clamping plates, a conventional injection molding machine, which has a screw shaft for plasticizing conventional plastics, such as thermoplastics, thermosets and elastomers and is therefore specifically designed for processing such plastics, can be quickly and easily converted to process silicone in the injection molding process.

[0033] The conversion process is just as easy as inserting a new tool shape into the clamping unit.

[0034] According to the invention, the injection unit actuator, which is already present in the conventional injection molding machine, is used to inject the silicone into the tool mold (more precisely, into the cavity of the tool mold).

[0035] The injection unit actuator, which is used in the processing of conventional plastics to press the nozzle of the injection unit against a mold half, is, in a sense, "repurposed" in the processing of silicone to insert the adapter piston into the adapter body and thus inject silicone from the silicone transfer chamber into the mold.

[0036] Through the injection unit process by means of the

[0037] The injection unit actuator can be moved towards the adapter body, thus allowing the adapter piston to be pushed further into the adapter body and thus injecting silicone located in the silicone transfer chamber into the mold via the injection channel.

[0038] If the injection unit is moved away from the adapter body again at a later time by the injection unit actuator, the injection unit lifts off the adapter piston again (lifting of the injection unit from the adapter piston).

[0039] In the processing of silicone, the injection of silicone into the tool mold is therefore expressly not carried out by an axial movement of the screw shaft within the cylinder housing (by means of a screw shaft actuator), but by a movement of the entire injection unit together with the cylinder housing by means of the injection unit actuator.

[0040] The processed silicone never enters the plasticizing volume of the injection unit. The silicone transfer chamber of the adapter body is fluidically separated from the plasticizing volume of the injection unit.

[0041] The processed silicone is therefore never in direct contact with the screw shaft and the inner wall of the cylinder housing during the injection process.

[0042] Cleaning the injection unit after processing silicone is therefore unnecessary. This represents a significant simplification, as cleaning the screw shaft and cylinder housing typically requires a complex disassembly and cleaning of the entire injection unit.

[0043] Furthermore, this method can significantly reduce silicone consumption, especially the silicone waste generated during production. This is because the 12774 / 3 / 1 WO silicone injection molding adapter

[0044] Since, according to the invention, the silicone does not come into contact with the screw shaft and the relatively large plasticizing volume, the amount of waste silicone, i.e., the silicone that remains in the injection molding machine after completion of the silicone processing and has to be removed during cleaning, can be significantly reduced.

[0045] In the following, some aspects and features of the injection molding machine according to the invention are explained and defined in more detail:

[0046] The clamping unit has two clamping plates that can be moved towards and away from each other by means of a clamping actuator. The two mold halves are each assigned to one of the two clamping plates and can be moved together with that clamping plate.

[0047] By moving the two clamping plates towards each other, the mold can be closed, closing the two mold halves. By moving the two clamping plates apart, the two mold halves can be lifted, thus reopening the mold for workpiece removal. Removing a workpiece from an open mold is also called demolding.

[0048] The adapter body and adapter piston define a piston chamber, the volume of which varies depending on how far the adapter piston is inserted into the adapter body. By inserting the adapter piston further into the adapter body, the piston chamber volume can be reduced, and any silicone contained within the piston chamber can be forced out through the injection channel.

[0049] Filling the silicone transfer chamber with silicone via the inlet channel involves feeding silicone into the 12774 / 3 / 1 WO silicone injection molding adapter.

[0050] The silicone transfer chamber is understood to be connected via the inlet channel. When the silicone transfer chamber is filled with silicone, the volume of the silicone in the silicone transfer chamber increases, causing the adapter piston to be at least partially pushed out of the adapter body (displacement of the adapter piston from the adapter body).

[0051] Because the adapter piston is displaced by the silicone flowing into the transfer chamber, (practically) no air enters the silicone transfer chamber. This is a significant advantage for the quality and reproducibility of the silicone injection molding process, as it prevents air inclusions in the silicone workpiece.

[0052] The formulation that the silicone transfer chamber is fluidically separated from the plastising volume of the injection unit expresses that, within the scope of the invention, there is no fluidic connection between the silicone transfer chamber and the plastising volume, i.e., within the scope of the invention, no fluid flows from the plastising volume into the silicone transfer chamber (or vice versa).

[0053] In particular, a 2-component silicone is used, the two components of which are mixed to form a homogeneous silicone immediately before being fed into the silicone transfer chamber (via the feed channel) using a static mixing tube.

[0054] According to a particularly preferred embodiment, the silicone injection molding adapter includes a shut-off valve, and the shut-off valve is arranged in the inlet channel and the inlet channel can be closed by means of the shut-off valve. 12774 / 3 / 1 WO Silicone injection molding adapter

[0055] Opening the shut-off valve in the inlet channel switches the shut-off valve so that silicone can flow through it.

[0056] To fill the silicone transfer chamber with the silicone to be processed and injected into the mold, the shut-off valve in the inlet channel is opened. The silicone to be processed is filled into the inlet channel, for example, using a hand pump or a (electrically, pneumatically, or hydraulically driven) feeding device. It then passes through the opened shut-off valve and enters the piston chamber, or the silicone transfer chamber, via the inlet channel. The silicone flowing into the silicone transfer chamber displaces the adapter piston from the adapter body, thus pushing the adapter piston out of the adapter body.

[0057] Once the desired amount of silicone has flowed into the silicone transfer chamber, the shut-off valve in the inlet channel is closed. This prevents further silicone from flowing through the inlet channel and also prevents silicone from escaping the silicone transfer chamber through the inlet channel during injection into the mold.

[0058] If, during this phase of filling the silicone transfer chamber through the feed channel, the mold is still closed and the workpiece produced in the previous injection molding cycle is still in the mold, it is possible to prevent silicone from unintentionally entering the mold during this phase without using an additional valve in the injection channel.

[0059] When the filling of the silicone transfer chamber is complete, no further silicone is supplied. This can be achieved, for example, by closing the inlet channel using the shut-off valve (12774 / 3 / 1 WO silicone injection molding adapter).

[0060] Furthermore, it can be advantageously provided that the silicone injection molding adapter has a heat insulation plate which is arranged between the adapter body and the mold half closest to the adapter body.

[0061] In this way, the intensity of heat exchange between the tool mold and the adapter body can be reduced.

[0062] The silicones used in injection molding typically cure by being heated. Therefore, cooling channels (or cooling elements) are sensibly provided in the adapter body to prevent premature curing of the silicone within the adapter body and thus ensure its flowability, while heating channels (or heating elements) are sensibly provided in the mold to cure the injected silicone into the workpiece as intended.

[0063] The thermal insulation plate impedes heat exchange between the adapter body and the mold. This prevents silicone from curing undesirably within the adapter body or curing too slowly or not at all within the mold. This benefits the quality of the manufactured component as well as process stability.

[0064] Against this background, the adapter body with its coolant channels offers a particularly advantageous feature.

[0065] The undesirable heat exchange between the adapter body and the mold can be further reduced by providing the silicone injection molding adapter 12774 / 3 / 1 WO silicone injection molding adapter with an injection nozzle, the injection channel extending at least partially through the injection nozzle, the injection nozzle being arranged in a corresponding recess of the adapter body and / or a corresponding recess of the adjacent mold half, and an annular space (especially air-filled) extending between the injection sleeve and the recess of the adapter body and / or the recess of the mold half.

[0066] In particular, the (air-filled) annular space between the relatively cold injection nozzle and the relatively warm mold half acts as insulation and hinders the unwanted heat exchange.

[0067] It is particularly advantageous if the injection nozzle has an external thread and the corresponding recess of the adapter body has a corresponding internal thread, so that the injection nozzle can be screwed into the corresponding recess of the adapter body, and / or the injection nozzle is tapered towards its end face facing the mold half (in order to further reduce the thermal conductivity between the mold half and the injection nozzle).

[0068] In this way, the desired heat exchange between the injection nozzle and the adapter body can be improved, and consequently, the temperature of the injection sleeve (with appropriate cooling of the adapter body) can be further reduced. This prevents unwanted hardening of the silicone in the injection channel (or in the injection sleeve), which can lead to a 12774 / 3 / 1 WO silicone injection molding adapter.

[0069] Blockage of the injection channel, which can necessitate its costly cleaning, can be prevented.

[0070] According to a particularly preferred embodiment of the invention, the geometry of the injection nozzle and the intensity of the cooling of the adapter body or the placement of cooling channels / elements provided therein (and / or the intensity of the heating of the mold or the placement of heating channels / elements provided therein) are coordinated so that, when the silicone cures in the mold, the silicone in the injection channel cures to form a sprue only in a small section of the channel adjacent to the mold cavity, while the silicone in the remaining area of ​​the injection channel is sufficiently cooled to remain liquid or flowable.

[0071] When the cured workpiece is removed from the open mold during demolding, the silicone that has cured to form the sprue is pulled out of the injection channel along with the workpiece. In the subsequent injection molding cycle, flowable silicone can then be injected back into the mold.

[0072] Removing the (complete) sprue plug along with the workpiece during demolding is only possible if the sprue plug does not exceed a certain maximum length, i.e., if it does not extend too far into the injection channel. Otherwise, the sprue plug will tear during demolding, leaving a residual plug in the injection channel. If this residual plug is long enough, it will prevent the flow of free-flowing silicone during the next injection molding cycle, thus necessitating cleaning of the injection channel. 12774 / 3 / 1 WO Silicone Injection Molding Adapter

[0073] The geometry of the injection nozzle, the design of the cooling of the adapter body and the heating of the tool shape, as well as the other process parameters, must therefore be selected in such a way that the sprue plug does not exceed a permissible maximum length.

[0074] According to another advantageous embodiment of the invention, the inlet channel does not penetrate either of the two clamping plates.

[0075] In this way, a silicone injection molding adapter can be implemented, which makes it particularly easy to retrofit an existing injection molding machine, as it eliminates the need for a structurally complex routing of the feed channel through a potentially existing opening in a clamping plate.

[0076] In order to easily and quickly adapt the amount of silicone to be injected and / or the injection pressure to be applied to the respective application, according to a further advantageous embodiment of the invention, it can be provided that the silicone injection molding adapter has a piston sleeve arranged in the adapter body, which at least partially limits the silicone transfer chamber, and the adapter piston is slidably mounted in the piston sleeve, and optionally the piston sleeve is interchangeably fixed in the adapter body by means of a quick-release fastener.

[0077] The piston sleeve and the associated adapter piston are matched in such a way that the adapter piston can be moved within the piston sleeve and both 12774 / 3 / 1 WO silicone injection molding adapters

[0078] Seal components against each other with respect to the silicone to be processed.

[0079] By using an adapter piston with a smaller (effective) piston cross-section, the injection pressure with which silicone is injected from the silicone transfer chamber through the injection channel into the mold can be increased - with the same force exerted by the injection unit actuator via the injection unit on the adapter piston.

[0080] The maximum injection pressure can therefore be influenced by the diameter of the adapter piston or the (effective) piston cross-section. The effective piston cross-section is understood to be the cross-sectional area of ​​the portion of the adapter piston that can be inserted into the piston sleeve.

[0081] A smaller effective piston cross-section leads to a higher maximum injection pressure, a larger effective piston cross-section to a lower maximum injection pressure.

[0082] Various piston sleeve-adapter piston pairings can be kept on hand and used to achieve different effective piston cross-sections and thus different maximum injection pressures.

[0083] The quick-release fastener allows for easy and quick replacement of piston sleeve-adapter piston pairings.

[0084] The present invention is further embodied in a silicone injection molding adapter according to the invention, which is suitable for use in an injection molding machine according to the invention. 12774 / 3 / 1 WO Silicone injection molding adapter

[0085] Furthermore, the invention manifests itself in a method according to the invention for injection molding silicone workpieces with an injection molding machine according to the invention comprising the following steps:

[0086] A) Closing of the mold by the clamping unit,

[0087] B) Lifting the injection unit from the adapter piston by moving the injection unit away from the clamping unit using the injection unit actuator,

[0088] C) Filling the silicone transfer chamber with silicone via the inlet channel, whereby the silicone entering the silicone transfer chamber causes an increasing displacement of the adapter piston from the adapter body,

[0089] D) Finishing the filling of the silicone transfer chamber,

[0090] E) Opening the mold by the clamping unit and removing the silicone workpiece located in the mold,

[0091] F) Closing of the mold by the clamping unit, and

[0092] G) Injecting silicone from the silicone transfer chamber through the injection channel into the mold by moving the injection unit using the injection unit actuator and simultaneously inserting the adapter piston into the adapter body.

[0093] The process steps A) to G) (or B) to G) of the process according to the invention form a complete cycle or injection cycle, which can be repeated any number of times.

[0094] In principle, one silicone workpiece (or a large number of silicone workpieces) can be produced during each injection molding cycle.

[0095] For the sake of clarity, the terms "silicone workpiece" or "workpiece" will be used in the following text in reference 12774 / 3 / 1 WO silicone injection molding adapter, referring to the singular. However, it is clear to those skilled in the art that, with appropriate tool design, several silicone workpieces can be produced simultaneously in a single injection cycle.

[0096] In step E), the silicone workpiece produced in the previous injection cycle is removed from the mold.

[0097] By removing the silicone workpiece only after the silicone transfer chamber has been refilled, it is possible to ensure that no silicone flows into the mold during the filling of the silicone transfer chamber, as the workpiece from the previous injection cycle still fills the cavity of the mold and thus prevents further silicone from flowing in.

[0098] Therefore, it is unnecessary to actively close the insertion channel using a separate valve.

[0099] When the silicone workpiece is removed, the silicone that has cured into a sprue plug in the injection channel is also removed. The injection channel is thus reopened, allowing flowable silicone to be injected into the mold again.

[0100] It is inherent in the process that during the first injection cycle, there is naturally no silicone workpiece from the previous injection cycle in the mold to block the injection channel during the filling of the silicone transfer chamber. Therefore, the following steps must be followed during the first injection cycle:

[0101] Closing of the mold by the clamping unit, 12774 / 3 / 1 WO silicone injection molding adapter

[0102] Lifting the injection unit from the adapter piston by moving the injection unit away from the clamping unit using the injection unit actuator, filling the silicone transfer chamber with silicone via the feed channel, whereby the silicone entering the silicone transfer chamber causes an increasing displacement of the adapter piston from the adapter body, completion of the filling of the silicone transfer chamber, injection of silicone from the silicone transfer chamber through the injection channel into the mold by moving the injection unit using the injection unit actuator and a concomitant insertion of the adapter piston into the adapter body.

[0103] Hardening of the workpiece in the tool mold, especially for about 1 to 5 minutes.

[0104] Subsequently, the inventive method for injection molding silicone workpieces with its steps A) to G) can be carried out in any number of cycles.

[0105] Therefore, when the silicone transfer chamber is first filled, some of the silicone will already flow into the mold.

[0106] This effect can be taken into account when determining the amount of silicone to be supplied via the feed channel during the initial filling of the silicone transfer chamber.

[0107] According to a preferred embodiment of the method according to the invention, the method comprises a step (Bl) in which the shut-off valve in the inlet channel is opened before, according to step (C), the silicone transfer chamber is filled with silicone via the inlet channel, and according to step (D) comprises stopping the filling of the silicone transfer chamber by closing the shut-off valve in the

[0108] Inlet channel . 12774 / 3 / 1 WO Silicone injection molded adapter

[0109] Some exemplary embodiments of the invention are explained in more detail below with reference to the drawings. Fig. 1 shows a schematic side view of an injection molding machine according to the invention with a silicone injection molding adapter shown in a sectional view.

[0110] Fig. 2 shows an enlarged sectional view of the silicone injection molding adapter according to Fig. 1.

[0111] Fig. 3 shows the silicone injection molding adapter according to Fig. 2 in an exploded view, and

[0112] Fig. 4 shows a flowchart of a method according to the invention for injection molding silicone workpieces with an injection molding machine according to the invention.

[0113] Figure 1 shows a schematic side view of an injection molding machine 1 according to the invention with a silicone injection molding adapter 2 shown in sectional view. In Figures 2 and 3, the silicone injection molding adapter 2 is enlarged and shown in an exploded view, respectively.

[0114] The injection molding machine 1 comprises a machine frame 3, a clamping unit 4 arranged on the machine frame 3, an injection unit 5, an injection unit actuator 6, a mold 7 and the silicone injection molding adapter 2.

[0115] The clamping unit 4 has two clamping plates 81, 8r and a clamping actuator 9, by means of which the two clamping plates 81, 8r can be moved towards and away from each other. The right of the two clamping plates shown in Fig. 1 (right clamping plate 8r) is fixed to the machine frame 3 (by means of a fixed bearing FL), while the left of the two clamping plates (left clamping plate 8r) is fixed to the machine frame 3.

[0116] On clamping plate 81 ) is (by means of loose bearing LL ) along the x- 12774 / 3 / 1 WO silicone injection molding adapter

[0117] Axis x is linearly movable relative to the machine frame 3. The right clamping plate 8r has an opening 36 into which an annular aperture 43 is inserted.

[0118] The injection unit 5 is mounted by means of a floating bearing LL so as to be linearly movable along the x-axis x relative to the machine frame 3 and comprises a cylinder housing 10 with a nozzle 11, a screw shaft 12 movable in the cylinder housing 10 and a plasticizing volume 13 extending between the cylinder housing 10 and the screw shaft 12.

[0119] The injection unit actuator 6 allows the injection unit 5, together with the cylinder housing 10 and the screw shaft 12, to be moved linearly along the x-axis relative to the machine frame 3.

[0120] The tool mold 7 has two tool halves 141, 14r, each assigned to one of the two clamping plates 81, 8r, and between which a cavity 15 extends, into which silicone can be supplied via a tool mold channel 16. The silicone curing in the tool mold 7 forms a (silicone) workpiece 17, which can be removed from the tool mold 7 when it is opened.

[0121] The left of the two mold halves (left mold half 141) is attached to the left clamping plate 81, the right of the two mold halves (right mold half 14r) is attached to the silicone injection molding adapter 2.

[0122] The right half of the tool mold 14r has an insert 19 placed in a corresponding receptacle 18, through which the tool mold channel 16 extends.

[0123] Insert 19 and the right mold half 14r could also be manufactured as a single piece. 12774 / 3 / 1 WO Silicone injection molding adapter

[0124] Furthermore, heating channels 20 for heating the silicone located in the tool mold 7 and ejection pins 21 for ejecting a solidified workpiece 17 from the tool mold 7 are provided in the right half of the tool mold 141, 14r.

[0125] The silicone injection molding adapter 2 includes an adapter body 22, an adapter piston 23, a piston sleeve 24, a shut-off valve 25, a heat insulation plate 26 and an injection nozzle 27.

[0126] The adapter body 22 is arranged between the right clamping plate 8r and the right mold half 14r and has a recess 28 into which the piston sleeve 24 is received, within which a silicone transfer chamber 29 extends. The adapter body 22 is penetrated by several coolant channels 30 through which a coolant can circulate.

[0127] Silicone can be supplied to the silicone transfer chamber 29 via an inlet channel 31. The shut-off valve 25 is located in the inlet channel 31. By rotating the shut-off valve 25, the inlet channel 31 can be closed or opened (released).

[0128] Silicone can be injected from the silicone transfer chamber 29 into the cavity 15 of the tool mold 7 (i.e. into the tool mold) via an injection channel 33 (and the tool mold channel 16).

[0129] The silicone transfer comb 29 is fluidically separated from the plasticizing volume 13 of the injection unit 5.

[0130] The piston sleeve 24 is fixed in the x-direction by means of a sleeve collar 34 and two easy-to-open quick-release fasteners 35 12774 / 3 / 1 WO silicone injection molding adapters.

[0131] The adapter piston 23 penetrates the opening 36 of the right-hand clamping plate 8r, is slidably mounted in the piston sleeve 24 or in the silicone transfer chamber 29, and can be partially inserted into the piston sleeve 24. A piston collar 37 limits the maximum insertion depth of the adapter piston 23 into the piston sleeve 24 when it abuts the end face of the piston sleeve 24.

[0132] The injection nozzle 27 has a through bore 38 through which the injection channel 33 extends. In a portion facing the adapter body 22, the injection nozzle 27 has an external thread 39, by means of which the injection nozzle 27 is screwed into a corresponding recess 40 of the adapter body 22, which has an internal thread. A portion of the injection nozzle 27 facing the tool mold 7 projects into a corresponding recess 41 of the adjacent right-hand tool mold half 14r (or into the corresponding recess 41 of the insert 19 of the right-hand tool mold half 14r). Between the recess 40 of the right tool mold half 14r and the injection nozzle 27, air-filled annular spaces 42 extend.

[0133] The thermal insulation plate 26 is arranged between the adapter body 22 and the right tool mold half 14r and has an opening through which the injection nozzle 27 extends.

[0134] The injection molding machine 1 according to the invention is used in the inventive method (100) shown as a flow diagram in Figure 4 and described below for injection molding silicone workpieces (17): 12774 / 3 / 1 WO Silicone injection molding adapter

[0135] First, in step A (110), the tool mold 7 is closed by the closing unit 4 by moving the two tool mold halves 141, 14r towards each other and pressing them together by the closing actuator 9.

[0136] According to step B (120), the injection unit 5 is lifted from the adapter piston 23 of the silicone injection molding adapter 2 by the injection unit actuator 6 moving the injection unit 5 away from the clamping unit 4. In the illustration in Figure 1, the injection unit 5 is moved to the right.

[0137] According to step Bl (125), the shut-off valve 25 in the inlet channel is opened.

[0138] Subsequently, in step C (130), the silicone transfer chamber 29 is filled with flowable silicone via the inlet channel 31. The silicone entering the silicone transfer chamber 29 causes a partial displacement of the adapter piston 23 from the adapter body 22. As shown in Figure 1, the adapter piston 23 is partially pushed out of the adapter body 22 to the right.

[0139] When the intended amount of silicone has flowed into the silicone transfer chamber 29, the filling of the silicone transfer chamber 29 is stopped in accordance with step D (140) by closing the shut-off valve 25 in the inlet channel 31.

[0140] Subsequently, in step E (150), the mold 7 is opened by the clamping unit 4 using the clamping actuator 9, and the silicone workpiece 17 located in the mold 7 is removed from the opened mold 7 (using the ejector pins 21). The silicone, which solidified to form the silicone workpiece 17, was injected into the mold 7 in the previous injection molding cycle. 12774 / 3 / 1 WO Silicone Injection Molding Adapter

[0141] Subsequently, according to step F (160), the tool mold 7 is closed again by the closing unit 4 using the closing actuator 9.

[0142] Subsequently, in step G (170), the silicone from silicone transfer chamber 29 is injected through the injection channel 33 (and the mold channel 16) into the (initially) empty cavity 15 of the mold 7 by moving the injection unit 5 towards the mold 7 by the injection unit actuator 6, so that first the nozzle 11 of the cylinder housing 10 of the injection unit 5 rests against the adapter piston 23 and then the adapter piston 23 is inserted into the piston sleeve 24, thereby forcing the silicone out of the silicone transfer chamber 29.

[0143] The silicone injected into the mold 7 then solidifies to form a silicone workpiece 17 and can be removed in step E of the next injection molding cycle.

[0144] 12774 / 3 / 1 WO Silicone injection molded adapter

[0145] Reference sign

[0146] Injection molding machine 1

[0147] Silicone injection molding adapter 2

[0148] Machine frame 3

[0149] Locking unit 4

[0150] Injection unit 5

[0151] Injection unit actuator 6

[0152] Tool shape 7 right on clamping plate 8r left on clamping plate 81

[0153] Closing actuator 9

[0154] Cylinder housing 10

[0155] Nozzle 11

[0156] worm shaft 12

[0157] Plasticizing volume 13 left mold half 141 right mold half 14r

[0158] Cavity 15

[0159] Tool mold channel 16

[0160] (Silicone) workpiece 17

[0161] Recording 18

[0162] Deployment 19

[0163] Heating channels 20

[0164] Exit pens 21

[0165] Fixed bearing FL

[0166] Loose bearing LL

[0167] Adapter body 22

[0168] Adapter piston 23

[0169] Piston sleeve 24

[0170] Shut-off valve 25

[0171] Thermal insulation panel 26

[0172] Injection nozzle 27

[0173] Exclusion 28

[0174] Silicone transfer chamber 29 12774 / 3 / 1 WO Silicone injection molding adapter

[0175] Coolant channels 30

[0176] Inlet channel 31

[0177] Injection channel 33

[0178] Sleeve collar 34

[0179] Quick release 35

[0180] Breakthrough 36

[0181] Piston collar 37

[0182] Bore 38

[0183] External thread 39

[0184] Recess 40, 41

[0185] Ring space 42 ring-shaped aperture 43

Claims

12774 / 3 / 1 WO Silicone injection molded adapter Claims 1. Injection molding machine (1) comprising a machine frame (3), a clamping unit (4) arranged on the machine frame (3) with two clamping plates (8r, 81), an injection unit (5) with a cylinder housing (10), a screw shaft (12) movable in the cylinder housing (10) and a plasticizing volume (13) extending between the cylinder housing (10) and the screw shaft (12), an injection unit actuator (6) by means of which the injection unit (5) together with the cylinder housing (10) and the screw shaft (12) can be moved relative to the clamping unit (4) along the machine frame (3), a mold (7) with two mold halves (14r, 141) each assigned to one of the two clamping plates (8r, 81), and a clamping element arranged between one of the two mold halves (14r) and one of the two clamping plates (8r). Silicone injection molding adapter (2) for injecting silicone into the tool mold (7) ,wherein the silicone injection molding adapter (2) comprises an adapter body (22) and an adapter piston (23), the adapter body (22) comprising a silicone transfer chamber (29), a closable feed channel (31) through which silicone can be supplied to the silicone transfer chamber (29), and an injection channel (33) through which silicone can be injected from the silicone transfer chamber (29) into the mold (7), 12774 / 3 / 1 WO Silicone injection molding adapter the silicone transfer chamber (29) is fluidically separated from the plasticizing volume (13) of the injection unit (5), the adapter piston (23) is slidably mounted in the silicone transfer chamber (29) and by moving the adapter piston (22) silicone can be injected from the silicone transfer chamber (29) via the injection channel (33) into the mold (7), and the adapter piston (23) can be inserted into the silicone transfer chamber (29) of the adapter body (22) by moving the injection unit (5) by means of the injection unit actuator (6).

2. Injection molding machine (1) according to claim 1, wherein the silicone injection molding adapter (2) comprises a shut-off valve (25), and the shut-off valve (25) is arranged in the inlet channel (31) and the inlet channel (31) can be closed by means of the shut-off valve (25).

3. Injection molding machine (1) according to one of the preceding claims, wherein the silicone injection molding adapter (2) has a heat insulation plate (26) arranged between the adapter body (22) and the mold half (14r) closest to the adapter body.

4. Injection molding machine (1) according to one of the preceding claims, wherein the adapter body (22) has coolant channels (30) shows.

5. Injection molding machine (1) according to one of the preceding claims, wherein the silicone injection molding adapter (2) has an injection nozzle (27), 12774 / 3 / 1 WO Silicone injection molding adapter the injection channel (33) extends at least partially through the injection nozzle (27), the injection nozzle (27) is arranged in a corresponding recess (40) of the adapter body and / or a corresponding recess (41) of the adjacent mold half (14r), and an annular space (42) which is particularly filled with air extends between the injection sleeve (27) and the recess (40) of the adapter body and / or the recess (41) of the mold half.

6. Injection molding machine (1) according to claim 5, wherein the injection nozzle (27) has an external thread (39) and the corresponding recess (40) of the adapter body has a corresponding internal thread, such that the injection nozzle (27) can be screwed into the corresponding recess (40) of the adapter body, and / or the injection nozzle (27) is tapered towards its end face facing the mold half (14r).

7. Injection molding machine (1) according to one of the preceding claims, wherein the feed channel (31) does not penetrate either of the two clamping plates (8r, 81).

8. Injection molding machine (1) according to one of the preceding claims, wherein the silicone injection molding adapter (2) has a piston sleeve (24) arranged in the adapter body (22) which at least partially limits the silicone transfer chamber (29), and the adapter piston (23) is slidably mounted in the piston sleeve (24), and optionally 12774 / 3 / 1 WO silicone injection molding adapter the piston sleeve (24) is fixed in the adapter body (22) by means of a quick-release fastener (35).

9. Silicone injection molding adapter (2) suitable for use in an injection molding machine (1) according to one of the preceding claims.

10. Method (100) for injection molding silicone workpieces (17) with an injection molding machine (1) according to any one of claims 1 to 8 comprising the following steps: A) Closing (100) of the tool mold (7) by the closing unit (4) , B) Lifting (110) the injection unit (5) from the adapter piston (23) by moving the injection unit (5) away from the closing unit (4) by means of the injection unit actuator (6) , C) Filling (120) the silicone transfer chamber (29) with silicone via the inlet channel (31), wherein the silicone entering the silicone transfer chamber (29) causes an increasing displacement of the adapter piston (23) from the adapter body (22), D) Completion (130) of filling the silicone transfer chamber (29) , E) Opening (140) the mold (7) by the clamping unit (4) and removing the silicone workpiece (17) located in the mold (7) , F) Closing (150) of the tool mold (7) by the clamping unit (4) , and G) Injecting (160) silicone from the silicone transfer chamber (29) through the injection channel (33) into the mold (7) by moving the injection unit (5) by means of the injection unit actuator (6) and a concomitant insertion of the Adapter piston (23) into the adapter body (22). 12774 / 3 / 1 WO Silicone injection molded adapter 11. Method according to claim 10, wherein the method comprises step Bl in which the shut-off valve (25) in the inlet channel (31) is opened (125) before, according to step C), the silicone transfer chamber (29) is filled with silicone via the inlet channel (31), and according to step D) the closing of the shut-off valve (25) in the inlet channel (31) to complete the filling of the silicone transfer chamber (29).

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