Injection molding assembly comprising two injection molding tools with coolable cold runner block

Abstract

The invention relates to an injection molding assembly for an injection molding machine, comprising at least one injection molding tool (3) with a coolable cold runner block (4) and at least one heatable molding block (6), wherein the at least one cold runner block (4) is made of a single part or two or more distributor plates (41) arranged one over the other and has at least one cold runner supply line with one or more branching points in which a change in direction and / or a division of the cold runner supply line occurs, and the molding block (6) comprises at least two molding plates (61, 62), between which cavities are formed, said supply lines opening into the cavities. A first coupling plate (1) is provided which has at least one main supply line (12) that opens into at least two distributor channels (15). At least two such injection molding tools (3) are arranged on the first coupling plate (1), the central supply lines (42) of said injection molding tools being connected to the main supply line (12) via the distributor channels (16). The invention additionally relates to a coupling plate for use as a first coupling plate (1) in such an injection molding assembly.

Description

[0001] INJECTION MOLDING ARRANGEMENT COMPRISING TWO INJECTION MOLDS WITH COOLABLE COLD RUNNER BLOCK

[0002] The invention relates to an injection molding arrangement for an injection molding machine, comprising at least one injection molding tool with a coolable cold runner block and at least one heatable mold block according to the preamble of patent claim 1.

[0003] Especially for the injection molding of liquid silicone rubber (LSR), injection molding machines use injection molding tools with a heatable mold block consisting of two mold plates, preceded by a cold runner block. To prevent vulcanization of the silicone material in the distribution channels of the cold runner block, the block is equipped with a cooling system that maintains the temperature of the cold runner block at approximately 18–30°C. To ensure sufficient cooling, it is common practice to equip the cold runner block with appropriate cooling channels. By preventing vulcanization in the distribution channels, sprue losses can be largely prevented, if not completely eliminated.

[0004] The cold runner block has a supply line connected to branching distribution channels through which the silicone material supplied by the injection molding machine is introduced via nozzles into the cavities formed between the mold plates of the mold block. To ensure sufficient cooling of the nozzle bodies over their entire length, it is common practice to equip them with cooling channels. Depending on the raw material, the silicone material can be fed through the injection molding machine via a static mixer or a mixing screw. The mold block is heated to 130 to 200 °C. The high temperatures activate the crosslinking process of the LSR material.

[0005] Such LSR injection molds, as disclosed with differently designed cold runner blocks, for example, in DE 3921355 A1, DE 40 14 244 A1, DE 10 2015 013 130 A1, or DE 9310529 U1, are very complex and cost-intensive. To maximize the productivity of the molds, the mold block is laboriously provided with the largest possible number of cavities, thereby increasing the number of products manufactured per injection molding process. To further increase production capacity, several injection molding machines equipped with such LSR injection molds are required, which significantly increases the investment costs.

[0006] This is where the present invention comes in. The invention is based on the object of providing an injection molding assembly for an injection molding machine that enables increased productivity while avoiding significant investment costs. According to the invention, this object is achieved by an injection molding assembly for an injection molding machine having the features of the characterizing part of patent claim 1.

[0007] The invention provides an injection molding arrangement for an injection molding machine that enables increased productivity while avoiding significant investment costs. By arranging a first coupling plate, which has at least one main supply line that opens into at least two distribution channels, with at least two such injection molding tools being arranged on the first coupling plate, whose central supply lines are connected to the main supply line via the distribution channels, productivity is doubled. The investment for this is essentially limited to one additional injection molding tool—the purchase of an additional injection molding machine is not necessary.The injection molding arrangement according to the invention also has the advantage that if an injection molding tool fails, the injection molding machine does not fail - it can continue production by replacing the coupling plate with a connecting plate with the remaining injection molding tool.

[0008] In a further development of the invention, the first coupling plate is formed from two interconnected distributor plates. This simplifies the manufacture of the distributor channels. The distributor channels are preferably milled. This enables manufacturing with very tight tolerances, thus preventing the formation of burrs and seams. Advantageously, the first coupling plate has a sprue bushing for connection to the nozzle of the injection unit of an injection molding machine. This facilitates the connection of the main supply line of the first coupling plate.

[0009] In one embodiment of the invention, the first coupling plate is provided with centering pins and / or centering holes that are positively connected to the centering holes and / or centering pins arranged on the injection molding tools. This ensures precise positioning of the injection molding tools on the first coupling plate.

[0010] In a further embodiment of the invention, the injection molding tools are connected to each other on the side opposite the first coupling plate via a second coupling plate. This enables the injection molding machine to open and close the injection molding tools synchronously.

[0011] In a further development of the invention, the injection molding tools are designed identically. This reduces the need for spare parts inventory. Furthermore, replacing temporarily broken injection molding tools is made easier.

[0012] In one embodiment of the invention, exactly two injection molding tools are arranged on the first coupling plate. This allows the setup of an injection molding machine without significant modifications, usually with an existing setup crane.

[0013] In a further embodiment of the invention, both coupling plates have a connecting piece for insertion into an injection molding machine. This enables a mechanical connection of the injection molding assembly to the injection molding machine.

[0014] The present invention further relates to a coupling plate for use as the first coupling plate of an injection molding assembly of the above type according to claim 8. Preferably, a sprue plate is arranged for pressure-tight connection to the injection unit of an injection molding machine, which opens into the main supply line. Other developments and refinements of the invention are specified in the remaining subclaims. An embodiment of the invention is illustrated in the drawings and will be described in detail below. They show:

[0015] Figure 1 shows a schematic representation of an injection molding arrangement for an injection molding machine;

[0016] Figure 2 shows the schematic representation of the injection molding arrangement from Figure 1 in cross section;

[0017] Figure 3 shows the schematic representation of the first coupling plate of the injection molding arrangement from Figure 1 in the view from below;

[0018] Figure 4 shows the schematic representation of the first coupling plate with injection molding tools with nozzle-side mold block half of the injection molding arrangement from Figure 1;

[0019] Figure 5 shows the schematic representation of the arrangement from Figure 4 in longitudinal section;

[0020] Figure 6 shows the schematic representation of the arrangement from Figure 4 in the view from below;

[0021] Figure 7 shows the schematic representation of an injection molding tool of the injection molding arrangement from Figure 1 with mounted sprue bushing for separate use in an injection molding machine and

[0022] Figure 8 shows a schematic sketch of an injection molding machine with an inserted injection molding arrangement.

[0023] The injection molding arrangement for an injection molding machine chosen as an exemplary embodiment is essentially formed by a first coupling plate 1 and a second coupling plate 2, between which two identically designed injection molding tools 3 are arranged, each having a cold runner block 4 which is connected to a mold block 6. For handling, the injection molding tools are provided with adjustable feet (not shown) and mounting bolts for a transport bridge, which have an eyelet for hanging in a

[0024] has a crane hook. The first coupling plate 1 comprises two interconnected distributor plates, a connecting plate 11 which has a main supply line 12 and which is provided with a sprue bushing 13 for connection to the nozzle of the injection unit of an injection molding machine, which opens into the main supply line 12, and a branch plate 14 through which two spaced-apart supply channels 15 are led. Between the connecting plate 11 and the branch plate 14 runs a connecting channel 16 which connects the main supply line 12 to the two supply channels 15. The supply channels 15 and the connecting channel 16 are dimensioned such that a material flow introduced through the main supply line 12 is guided in equal parts through the supply channels 15.

[0025] The cold runner block 4 is formed from an arrangement of four adjacent distributor plates 41, through each of which inlet channels 42 are led. These inlet channels are connected via connecting channels 43 running between each two distributor plates. Adjacent to the four distributor plates 41 is a nozzle holding plate 44, in which nozzles 45 are arranged, into each of which an inlet channel 42 opens. To cool the cold runner block 4, including the nozzles 45 arranged in the nozzle holding plate 44, cooling channels (not shown) are also led through it, which are fed with a coolant via cooling connections (not shown). Centering mandrels 46 are arranged on the cold runner block 4 and engage in centering bores 17 in the first coupling plate 1, whereby the cold runner block 4 is positioned precisely on the first coupling plate 1.

[0026] The mold block 6 comprises two mold plates 61, 66 that accommodate molded pieces 63, between which cavities are formed. The two mold plates 61, 66 are guided toward each other via centering elements 64, so that they are precisely positioned relative to each other after a closing process. The mold block 6 is provided with resistance heating elements (not shown) that are connected to an electrical power supply via connectors 32, 33.

[0027] The first mold plate 61 is connected to the nozzle holder plate 44 of the cold runner block 4 via a thermal insulation plate 65, with each of the nozzles 45 held by the nozzle plate 44 opening into one of the cavities formed by the mold pieces 63. The thermal insulation plate 65 serves to thermally separate the cooled cold runner block 4 from the heated mold block 6.

[0028] The second mold plate 66 is connected to a core holding plate 62, which, in a known manner (not shown), accommodates movable core modules as components of molded pieces 63 for creating undercuts in products to be manufactured. The core holding plate 62 is connected via a further thermal insulation plate 65 to a pressure plate 67, which is connected to the second coupling plate 2.

[0029] The second coupling plate 2 has hydraulically actuated ejector pins 21, which are guided by the pressure plate 67, the thermal insulation plate 65 adjacent thereto, and the core holding plate 62. Furthermore, fastening elements 22 for mechanical connection to a movable carriage of an injection molding machine 7 are arranged on the coupling plate 2. Furthermore, the coupling plate 2 has an ejector connection 23 for moving the retracting mold plate 66.

[0030] Figure 8 schematically illustrates an injection molding machine into which an injection molding assembly according to the invention is installed. The first coupling plate 1 is firmly screwed to the injection molding machine 7, with the sprue bushing 13 being pressure-tightly connected to an injection unit 72 connected to the mixer 71. The second coupling plate 2 is firmly connected to the movable carriage 73 of the injection molding machine 7 via the fastening elements 22, with the ejector connection being connected to an ejector actuator (not shown) arranged on the carriage 73 of the injection molding machine 7, for example, a hydraulic cylinder.

[0031] In a production cycle, liquid silicone material is fed from the mixer 71 via the injection unit 72 at a temperature of approximately 25 to 35 degrees under high pressure via the sprue bushing 13 through the main feed line 12 via the inlet and connecting channels 15, 16 in equal parts to the inlet and connecting channels 42, 43 of the cooled cold runner blocks 4 of the two injection molding tools 3, which are identical in the exemplary embodiment, and injected through the nozzles 45 into the cavities formed by the mold pieces 63 of the heated mold blocks 6, where it is heated and solidified by a chemical reaction, for example crosslinking or vulcanization. Subsequently, the core holding plate 62 is first separated from the mold plate 66 via the ejector pins 21, whereby the cores held by the core holding plate 62 are moved out of the mold pieces 63.

[0032] Subsequently, the carriage 73 of the injection molding machine 7 with the second coupling plate 2 attached to it is retracted, whereby the two injection molding tools 3 are synchronously separated along the parting plane between the two mold plates 61, 66 of their mold blocks 6. This separates the two mold plates 61, 66, whereby the products formed by the mold pieces 63 are removed from both injection molding tools 3. Depending on the product, this process can be accelerated by a roller moving over the mold pieces 63.

[0033] Subsequently, the carriage 73 of the injection molding machine 7, with the second coupling plate 2 attached to it, is moved back to its first position, whereby the second mold plates 66 of the two injection molding tools 3 are synchronously and tightly placed against the first mold plates 61. The second mold plates 62 are precisely positioned against the first mold plates 61 via the centering elements 64. At the same time, the core holding plates 62 are placed back against the second mold plate 66.

[0034] In the event of a failure of one of the injection molding tools 3, for example due to maintenance, this can either be replaced by an identical injection molding tool 3, or the remaining injection molding tool 3 can, as shown in Figure 7, be provided with a sprue bushing 5 which opens into the inlet channel 42 of the cold runner block 4.

[0035] The injection molding arrangement according to the invention enables a cost-effective increase in the productivity of an injection molding machine, while at the same time enabling production to be continued in the event of, for example, a maintenance-related failure of an injection mold.

Claims

Patent claims 1. Injection molding arrangement for an injection molding machine, comprising at least one injection molding tool (3) with a coolable cold runner block (4) and at least one heatable mold block (6), wherein the at least one cold runner block (4) is formed in one piece or from two or more superimposed distributor plates (41) and has at least one cold runner supply line with one or more branching points at which a change of direction and / or a division of the cold runner supply line takes place, and wherein the mold block (6) comprises at least two mold plates (61, 62), between which cavities are formed into which the cold runner supply lines open, characterized in that a first coupling plate (1) is arranged, which has at least one main supply line (12) which opens into at least two distributor channels (15), wherein at least two such injection molding tools (3) are arranged on the first coupling plate (1),whose central supply lines (42) are connected to the main supply line (12) via the distribution channels (16).

2. Injection molding arrangement according to claim 1, characterized in that the first coupling plate (1) is formed from two interconnected distributor plates (11, 14).

3. Injection molding arrangement according to claim 1 or 2, characterized in that the first coupling plate (1) is provided with centering mandrels and / or centering bores (17) which are positively connected to centering bores and / or centering mandrels (46) arranged on the injection molding tools (3).

4. Injection molding arrangement according to one of the preceding claims, characterized in that the injection molding tools (3) are connected to one another on their side opposite the first coupling plate (1) via a second coupling plate (2).

5. Injection molding arrangement according to one of the preceding claims, characterized in that the injection molding tools (3) are of identical design, wherein preferably two injection molding tools (3) are arranged on the first coupling plate (1).

6. Injection molding arrangement according to one of the preceding claims, characterized in that the first coupling plate (1) has a sprue bushing for connection to the nozzle of the injection unit of an injection molding machine (7).

7. Injection molding arrangement according to one of claims 4 to 6, characterized in that both coupling plates (1, 2) have connecting means for receiving in an injection molding machine (7).

8. Coupling plate for use as a first coupling plate (1) in an injection molding arrangement according to one of the preceding claims, comprising at least one main supply line (12) which opens into at least two distribution channels (15), wherein the coupling plate (1) has receptacles for at least two injection molding tools (3), the central supply lines (42) of which are connected to the main supply line (12) via the distribution channels (16).

9. Coupling plate according to claim 8, characterized in that a sprue plate (3) is arranged for pressure-tight connection to the injection unit (72) of an injection molding machine (7), which opens into the main supply line (12).

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