Coinjection Hot Runner Nozzles

Abstract

The present invention relates to the field of injection molding technology, and discloses a co-injection hot runner nozzle comprising a nozzle and a torpedo-shaped inner nozzle. The nozzle is hollow and the inner nozzle is fixed within the nozzle, forming an outer layer runner between the inner nozzle and the nozzle; an intermediate layer runner is defined within the sidewall of the inner nozzle, and an inner layer runner is defined within the inner nozzle; the intermediate layer runner is provided with an injection runner fixed to the inner nozzle, and the injection runner is connected to the intermediate layer runner. The present invention has a simple structure, and flow is divided by the nozzle and the torpedo-shaped inner nozzle to achieve balanced molten material flow, so that the front end of the injected intermediate layer is flat and forms concentric circles.

Description

Technical Field

[0001] The present invention relates to the technical field of injection molding, in particular to a co-injection hot runner nozzle. Background Art

[0002] The hot runner nozzle is a common component in injection mold systems. It heats the hot runner and gate to keep the plastic molten. Because a heating coil is installed near the runner, the entire hot runner from the nozzle inlet to the gate is kept at a high temperature, keeping the plastic molten. After shutdown, it is generally not necessary to open the hot runner to remove the solidified material.

[0003] In the prior art, multi-layer injection molding using hot runner nozzles is being investigated. Chinese patent publication number CN208035219U proposes a hot runner nozzle with four tulip-shaped flow paths, combined into a ring. However, due to changes in cross-sectional shape and thickness, the rheological behavior changes once the molding conditions change, making it difficult to achieve rheological balance, resulting in a wavy front end in the middle layer of the molded product (poor performance). Chinese patent publication number CN1234763A proposes a coat-hanger-shaped hot runner nozzle. However, coat-hanger-shaped hot runners are not easy to achieve rheological balance, causing the melt front end to deflect within a certain angle, resulting in an uneven front end in the molded middle layer. Furthermore, in the manufacture of plastic parts, Chinese patent publication number CN1509227A employs two opposing structures to control the melt's rheological balance. Slight differences in the flow velocity at the front end of the middle layer within the runners can amplify the deflection, making it difficult to achieve and achieving a relatively flat front end.

[0004] In order to provide a better front end for injection molding the intermediate layer, it is necessary to improve the co-injection hot runner nozzle. Summary of the Invention

[0005] The present invention aims to provide a co-injection hot runner nozzle so that the front end of the injected intermediate layer is flat and forms concentric circles.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a co-injection runner nozzle, comprising a nozzle and an inner nozzle of a torpedo body, the nozzle being hollow and the inner nozzle being fixed inside the nozzle, an outer layer runner being formed between the inner nozzles and the nozzles; an intermediate layer runner being provided in the side wall of the inner nozzle, an inner layer runner being provided in the inner nozzle; an injection molding runner fixed on the inner nozzle being provided in the intermediate layer runner.

[0007] Principles and beneficial effects of the present invention:

[0008] In the prior art, it is difficult to achieve rheological balance when performing injection molding using a petal-shaped or hanger-shaped hot runner nozzle, which causes the front end of the molten material middle layer to be deflected, resulting in an uneven front end of the injected middle layer.

[0009] In this solution, (1) a torpedo-shaped inner nozzle is used to directly divert the flow through the inner wall of the nozzle and the outer wall of the inner nozzle, without the need for a complex diversion flow channel, so that the molten material finally forms a circular flow, thereby having low resistance and low pressure loss, so as to adapt to the injection molding of thin-walled products and products requiring high-speed injection molding.

[0010] (2) Since the torpedo body has a certain taper, the flow rate decreases slowly with the increase of the cross-sectional area, which conforms to the flow principle. The molten plastic is compressed so that after converging, a better uniform flow balance is formed. At the same time, the balanced flow of the entire circle moving forward synchronously in the torpedo body can easily achieve the rheological balance of the melt, making the front end of the injection molded middle layer smooth.

[0011] (3) The injection molding runner makes the melt entering the middle layer runner more uniform.

[0012] Compared with the petal-shaped and hanger-shaped flow channels in the prior art, this solution can inject a concentric and flat front end of the middle layer, reducing the deflection and wavy shape of the front end of the middle layer and improving the injection molding effect.

[0013] Furthermore, a support ring is integrally formed on or detachably connected to the inner nozzle, a support column is integrally formed on or detachably connected to the inner side wall of the support ring, the support ring is integrally formed on or detachably connected to the inner nozzle through the support column, the injection runner passes through the support column, and the support ring and the inner nozzle form the inlet of the outer layer runner due to the support of the support column.

[0014] Beneficial Effects: While existing nozzles are single- or double-layer structures, this solution integrates the inner nozzle with a support ring or provides a detachable connection. This solution also incorporates an outer nozzle structure, overcoming the technical difficulty of implementing a three-layer injection runner in existing technologies. This design overcomes the technical challenge of melt entry into the torpedo body's sidewalls and provides a feasible solution. The support column serves both to support the inner nozzle and to provide a channel for the injection runner.

[0015] Furthermore, the injection molding runner spiral is evenly distributed on the side wall of the inner nozzle, and a spiral groove is arranged between the injection molding runner and the middle layer runner. The spiral groove gradually becomes shallower and the spiral groove is arranged with an inclination angle of 3° to 5°. The connecting gap between the spiral groove and the middle layer runner gradually increases, and the connecting gap is arranged with an inclination angle of 1.5° to 2.5°.

[0016] Beneficial effects: The injection runner spirals are evenly distributed on the inner nozzle, and the gap between the spiral injection runners and the injection channels gradually increases. Corresponding grooves are set to make the spiral injection runners and the inner nozzle form corresponding inclination angles, ensuring that the connection between the injection runner and the middle layer runner gradually increases in inclination. After the molten material passes through the spiral and merges, it forms a synchronously moving full circle, ensuring the rheological balance of the molten material.

[0017] Furthermore, the injection molding runners are in a petal shape on the side wall of the inner nozzle and there are more than or equal to 4 injection molding runners.

[0018] Beneficial effect: The molten material forms a full circle at the end of the nozzle through the injection runner and is finally injected into the cavity at the same time, thus reducing the wavy effect at the front end of the middle layer.

[0019] Furthermore, the injection molding runner is sleeved on the inner nozzle, and the injection molding runner is a combination of a petal shape and a spiral channel. The injection molding runner is provided with a plurality of arc-shaped grooves evenly distributed on the injection molding runner. The connecting gap between the arc-shaped grooves and the middle layer runner gradually increases, and the injection molding runner is provided with a plurality of columns evenly distributed on the injection molding runner.

[0020] Beneficial effects: When the molten material flows in the injection molding runner, the flow is blocked by the column, achieving the effect of a static mixer, making the temperature and speed of the molten material more uniform, avoiding the unevenness caused by shear heating generated by the flow of the molten material. At the same time, the injection molding runner is formed by the petal-shaped and spiral channels. The injection molding runner allows the molten material to form a full circle at the end of the nozzle and finally be injected into the cavity at the same time, thereby reducing the wavy effect at the front end of the middle layer.

[0021] Furthermore, the injection molding runner is sleeved on the inner nozzle, and a plurality of columns evenly distributed on the injection molding runner are provided on the injection molding runner.

[0022] Beneficial effect: When the molten material flows in the injection runner, it is blocked by the column to achieve the effect of a static mixer, making the temperature and speed of the molten material more uniform, avoiding unevenness caused by shear heating generated by the flow of the molten material.

[0023] Furthermore, a valve needle is provided in the inner flow channel.

[0024] Beneficial effect: The flow rate of the molten material in the inner flow channel can be adjusted by the valve needle.

[0025] Furthermore, a nozzle seat is fixedly connected to the outer side wall of the nozzle.

[0026] Beneficial effect: The nozzle is easily connected to the main pipeline through the nozzle seat.

[0027] Furthermore, the nozzle is threadedly connected to the nozzle seat.

[0028] Beneficial effect: The nozzle and the nozzle seat are threadedly connected to facilitate the disassembly and assembly of the nozzle and the nozzle seat, thereby improving installation efficiency.

[0029] Furthermore, the inner nozzle is integrally formed with the injection runner or is detachably connected thereto.

[0030] Beneficial effects: The inner injection molding and the injection runner are integrally formed, which is convenient for manufacturing the inner nozzle, and the detachable connection is convenient for component polishing and installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is an axonometric view of the co-injection hot runner nozzle in Example 1 of the present invention;

[0032] Figure 2 for Figure 1 Front view of

[0033] Figure 3 for Figure 2 FF cross-sectional view;

[0034] Figure 4 for Figure 3 A magnified view of part A;

[0035] Figure 5 Schematic diagram of the support column structure in embodiments 1, 2, 3, and 4 of the present invention;

[0036] Figure 6 Schematic diagram of the structure of the injection molding runner and the support ring in the first embodiment of the present invention;

[0037] Figure 7 Schematic diagram of the structure of the injection molding runner in Example 1 of the present invention;

[0038] Figure 8 FF sectional view of the inner nozzle in the second embodiment of the present invention;

[0039] Figure 9 Schematic diagram of the structure of the injection molding runner and the support ring in the second embodiment of the present invention;

[0040] Figure 10 Schematic diagram of the structure of the injection molding runner in the second embodiment of the present invention;

[0041] Figure 11 FF sectional view of the inner nozzle in the third embodiment of the present invention;

[0042] Figure 12 Schematic diagram of the structure of the injection molding runner and the support ring in the third embodiment of the present invention;

[0043] Figure 13 Schematic diagram of the structure of the injection molding runner in the third embodiment of the present invention;

[0044] Figure 14 FF sectional view of the inner nozzle in the fourth embodiment of the present invention;

[0045] Figure 15 Schematic diagram of the structure of the injection molding runner and the support ring in the fourth embodiment of the present invention;

[0046] Figure 16 This is a schematic structural diagram of the injection molding runner in Example 4 of the present invention. DETAILED DESCRIPTION

[0047] The following is further described in detail through specific implementation methods:

[0048] The figure marks in the drawings of the specification include: nozzle 1, outer layer runner 11, inner nozzle 2, middle layer runner 21, inner layer runner 22, support ring 3, injection runner 4, arc-shaped groove 41, column 42, petal-shaped channel 43, support column 31, nozzle seat 5, and valve needle 6.

[0049] Example 1:

[0050] Basically as attached Figure 1 To the attached Figure 7 As shown, a coinjection hot runner nozzle includes a hollow nozzle 1, an inner nozzle 2 with a torpedo-shaped longitudinal section, and a support ring 3. The outer diameter of the left end of the torpedo is larger than that of the right end, that is, an inlet with a certain taper can be formed in the support ring.

[0051] Attachment Figure 3 As shown, the inner nozzle 2 has an intermediate layer flow channel 21 in the side wall, and the intermediate layer flow channel 21 is connected to the injection flow channel 4 integrally formed on the side wall of the inner nozzle 2. Of course, the inner nozzle 2 and the injection flow channel 4 can also be disassembled as components, as shown in the attached figure. Figure 4 As shown, a spiral groove is formed between the injection molding runners 4, the spiral groove gradually becomes shallower and maintains an inclination angle β of 3° to 5°, the injection molding runners 4 are connected with the spiral groove, and the communication gap between the injection molding runners 4 and the spiral groove gradually increases and has a certain inclination angle α. In this embodiment, the inclination angle α is 1.5° to 2.5°.

[0052] As attached Figure 6 and Figure 7 As shown, in this embodiment, there are four injection molding runners 4, and the four injection molding runners 4 are spirally distributed on the inner nozzle 2. Figure 5 As shown, support columns 31 are integrally formed on the inner sidewall of the support ring 3. The support ring 3 is integrally formed with the inner nozzle 2 via the support columns 31. Of course, the inner nozzle 2 and support ring 3 can also be assembled as separate components. In this embodiment, there are four hollow support columns 31. Four injection runners 4 are located within the support columns 31 and penetrate the support ring 3 to communicate with the outside. The area between the support ring 3 and the inner nozzle 2 forms the inlet of the outer runner 11.

[0053] As attached Figure 3As shown, the inner nozzle 2 is provided with an inner layer flow channel 22, and the outer layer flow channel 11, the inner layer flow channel 22 and the middle layer flow channel 21 are connected at the left end of the nozzle 1 and the inner nozzle 2, and the connection is smooth. The outer wall of the nozzle 1 is threadedly connected to the nozzle seat 5, and the nozzle seat 5 is provided with a main pipeline, which is respectively connected to the outer layer flow channel 11 and the inner layer flow channel 22. The valve needle 6 is detachably connected to the inner layer flow channel 22. The outer wall of the nozzle seat 5 is provided with an external thread. The nozzle seat 5 is provided with a heating element. In this embodiment, the heating element is a heating coil, which is fixed by a tightening screw and is used to heat the molten material during the injection molding process (not shown in the figure).

[0054] The specific implementation process is as follows:

[0055] Injection molding is divided into two parts, Figure 3 As shown in the figure, the direction of the melt flow is as shown by the arrows. The first part: the melt is sent into the inner layer runner 22 and the outer layer runner 11 through the main pipeline at a certain pressure. The second part: the melt is sent into the middle layer runner 21 through the four injection runners 4 at a certain pressure. The above two parts are used to divide the melt flow and achieve rheological balance of the melt during the injection process.

[0056] The molten materials in the outer layer flow channel 11, the middle layer flow channel 21 and the inner layer flow channel 22 converge at the connection point of the three. Since the connection point of the three is a smooth transition and at the same time, due to the rheological balance of the molten material, a concentric middle layer front end can be formed and the middle layer front end is basically flat.

[0057] Example 2:

[0058] The difference between the second embodiment and the first embodiment is that Figure 8 , Attachment Figure 9 and attached Figure 10 As shown, the injection runner 4 is integrally formed on the inner nozzle 2, and the injection runner 4 is evenly distributed on the outer periphery of the inner nozzle 2. In this embodiment, the injection runner 4 is any number of four, six, eight, or twelve. In this embodiment, there are eight injection runners, and the injection runners 4 are evenly distributed with the middle layer runner 21 as the center. Each injection runner 4 forms two as shown in the attached figure. Figure 9 and attached Figure 10 In the petal-shaped channel 43 shown, the injection runner 4 is located within the support column 31 and penetrates the support ring 3. The support ring 3 and the inner nozzle 2 form the inlet of the outer layer runner 11. The molten material is injected through the petal-shaped injection runner 4, so that the molten material forms a concentric circle at the front end of the nozzle, and is finally injected into the middle layer runner 21 at the same time, so that the molten material at the front end of the middle layer does not deflect.

[0059] Example 3:

[0060] The difference between the third embodiment and the first embodiment is that Figure 11 , Attachment Figure 12 and attached Figure 13 As shown, the injection runner 4 is integrally formed on the inner nozzle 2. The injection runner 4 is connected to four ports. The upper part of the injection runner 4 is a petal-shaped channel 43, and the lower part of the injection runner 4 is a spiral channel. The petal-shaped channel 43 is connected to the spiral channel. The injection runner 4 has a number of columns 42 fixed on the petal-shaped channel 43. The columns 42 are located in the injection runner 4. When the molten material flows in the injection runner 4, it is blocked by the columns 42. During the rotation of the nozzle, the effect of a static mixer is achieved, making the molten material more uniform and avoiding the unevenness caused by the shear heating of the molten material due to the rotation of the nozzle. The injection runner 4 is provided with an arc-shaped groove 41. The arc-shaped grooves 41 are evenly distributed on the injection runner 4 to form a spiral channel. The gap at the connection between the arc-shaped groove 41 and the middle layer runner 21 gradually increases. Combined with the attached Figure 5 As shown, the injection runner 4 is located inside the support column 31 and passes through the support ring 3. The support ring 3 and the nozzle 1 form the inlet of the outer layer runner 11. The injection runner 4 is formed by the petal-shaped channel 43 and the spiral channel. The injection runner 4 allows the molten material to form a full circle at the end of the nozzle and finally be injected into the cavity at the same time, thus reducing the wavy effect at the front end of the middle layer.

[0061] Example 4:

[0062] The difference between the fourth embodiment and the first embodiment is that, as shown in the attached Figure 14 , Attachment Figure 15 and attached Figure 16 As shown, the injection channel 4 is integrally formed on the inner nozzle 2, and a number of columns 42 are integrally formed on the injection channel 4. When the molten material flows in the injection channel 4, the columns 42 are used to block the flow. During the rotation of the nozzle, the static mixer effect is achieved, making the molten material more uniform and avoiding unevenness caused by shear heating generated by the rotation of the nozzle. Figure 5 As shown, the injection runner 4 passes through the support ring 3 and is located within the support column 31. The area between the support ring 3 and the inner nozzle 2 forms the inlet of the outer runner 11. The injection runner 4 is fixed to the support ring 3. The injection runner 4 transports the molten material to the middle runner 21, which is suitable for the injection molding of thin-walled products and products that require high-speed injection molding.

[0063] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art may make various modifications and improvements without departing from the scope of the present invention. These modifications and improvements should also be considered within the scope of protection of the present invention and will not affect the effectiveness of the implementation of the present invention or the practical application of the patent. The technologies, shapes, and structural components omitted from the present invention are all well-known technologies.

Claims

1. A coinjection hot runner nozzle, characterized by: The nozzle comprises a nozzle and an inner nozzle of the torpedo body, wherein the nozzle is hollow and the inner nozzle is fixed inside the nozzle, and an outer layer flow channel is formed between the inner nozzle and the nozzle; an intermediate layer flow channel is opened in the side wall of the inner nozzle, and an inner layer flow channel is opened in the inner nozzle; an injection molding flow channel fixed on the inner nozzle is provided in the intermediate layer flow channel; The injection molding runner spiral is evenly distributed on the side wall of the inner nozzle, a spiral groove is provided between the injection molding runner and the intermediate layer runner, the spiral groove gradually becomes shallower toward the discharge port and the spiral groove is provided with an inclination angle of 3° to 5°, the communication gap between the spiral groove and the intermediate layer runner gradually increases toward the discharge port, and the communication gap is provided with an inclination angle of 1.5° to 2.5°; A support ring is integrally formed on the inner nozzle or detachably connected thereto, a support column is integrally formed on the inner side wall of the support ring or detachably connected thereto, the support ring is integrally formed on the inner nozzle or detachably connected thereto through the support column, the injection runner passes through the support column, and the support ring and the inner nozzle form the inlet of the outer runner due to the support of the support column.

2. The coinjection hot runner nozzle according to claim 1, characterized in that : The injection molding runner is petal-shaped on the side wall of the inner nozzle and the number of injection molding runners is greater than or equal to 4.

3. The coinjection hot runner nozzle according to claim 1, characterized in that: The injection molding runner is sleeved on the inner nozzle, and the injection molding runner is a combination of a petal shape and a spiral channel. The injection molding runner is provided with a plurality of arc-shaped grooves evenly distributed on the injection molding runner. The connecting gap between the arc-shaped grooves and the middle layer runner gradually increases, and the injection molding runner is provided with a plurality of columns evenly distributed on the injection molding runner.

4. The coinjection hot runner nozzle according to claim 1, characterized in that: The injection molding flow channel is sleeved on the inner nozzle, and a plurality of columns evenly distributed on the injection molding flow channel are arranged on the injection molding flow channel.

5. The coinjection hot runner nozzle according to any one of claims 1 to 4, characterized in that: A valve needle is arranged in the inner layer flow channel.

6. The coinjection hot runner nozzle according to any one of claims 1 to 4, characterized in that: A nozzle seat is fixedly connected to the outer side wall of the nozzle.

7. The coinjection hot runner nozzle according to claim 6, characterized in that: The nozzle is threadedly connected to the nozzle seat.

8. The coinjection hot runner nozzle according to claim 1, characterized in that: The inner nozzle is integrally formed with the injection runner or is detachably connected thereto.

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