CN105690676B

CN105690676B - Injection molding apparatus with heated mold cavity

Info

Publication number: CN105690676B
Application number: CN201511035922.7A
Authority: CN
Inventors: G·奥拉鲁
Original assignee: Otto Maenner Innovation GmbH
Current assignee: Otto Maenner Innovation GmbH
Priority date: 2014-12-11
Filing date: 2015-12-10
Publication date: 2019-12-31
Anticipated expiration: 2035-12-10
Also published as: CN105690676A; JP2016128252A; DE102015225028A1

Abstract

An injection molding apparatus for laterally casting a moldable article having an injection manifold, a plurality of hot runner nozzles, a first nozzle heater, a plurality of mold cavities positioned for receiving molten material from the plurality of hot runner nozzles, each mold cavity having at least one mold gate orifice and a mold cavity heater at least partially surrounding each mold cavity, and a thermocouple associated with the mold cavity to directly or indirectly measure a temperature generated by the mold cavity heater.

Description

Injection molding apparatus with heated mold cavity

Technical Field

The present invention relates to a hot runner (hot runner) injection molding apparatus. More particularly, the present invention relates to a hot runner injection molding apparatus for side casting with improved mold cavity temperature control.

Background

The temperature of the molten material as it passes through the manifold, the hot runner nozzle and within the cavity is critical to the later quality of the product in the same cavity, between cavities, during the same injection cycle and between successive injection cycles for the preparation of injection molded articles, and particularly when the hot runner nozzle is used to laterally pour the molded article. Significant efforts have been made to control the temperature of all the components that direct the molten material to the cavity, but these efforts have not addressed the key issues of hot runner nozzles for side pouring.

In the present invention, we have sought to improve the hot runner nozzle for side pouring of at least two known designs.

In a first known design, shown in fig. 9, a single mold cavity has a single mold gate and molten material is injected through a single nozzle tip. The nozzle tip is of the hot runner nozzle which may have a single tip or at least two nozzle tips. In these designs, the flow of molten material within the mold cavity is split around the mold core and formed behind the mold core into two streams of molten material. The flow of such two streams of molten material within the mold cavity is affected by the presence of a thin layer of frozen forming material that begins to form near the gate and may form not only on the cold wall of the mold cavity, but also around the cold mold core. These frozen layers can affect the environment of the mold cavity and the quality of the part. When two separate streams of molten material meet, a weld line will also be formed behind the core. The weld line may be visible or may weaken the formed part. Therefore, such weld lines are undesirable.

In a second known design, shown in fig. 10, a single mold cavity has at least two mold gates, and molten material is injected directly onto and around the mold core through two separate nozzles and two separate nozzle tips. In these designs, there are two streams of molten material around the mold core within the mold cavity. These flows are affected by the presence of a thin frozen shape material layer that begins to form near the gate and may form not only on the cold wall of the mold cavity, but also around the cold mold core. These frozen layers can affect the environment of the mold cavity and the quality of the part. In these designs, when the two flows meet in the mold cavity, flow lines will likely form. The weld line may be visible or may weaken the molded part. Therefore, such weld lines are undesirable.

Disclosure of Invention

The present invention therefore meets this need by providing control of the temperature of the molten material and/or the parts directing the molten material to the mold cavity for improving the quality of the molded article.

The present invention is directed to this object throughout the entire text and in the independent claims. Preferred further developments of the invention form the subject matter of the dependent claims.

An injection molding apparatus for laterally casting a moldable article is provided that includes an injection manifold having at least one manifold input melt channel and a plurality of manifold output melt channels, the manifold heated by at least one manifold heater controlled by at least one manifold thermocouple.

The injection molding apparatus further includes a plurality of side-pouring hot runner nozzles coupled to the manifold. Each hot runner nozzle includes at least one input melt channel portion having a first axis and at least one output melt channel portion having a second axis.

The injection molding apparatus further includes a first nozzle heater and a first nozzle thermocouple secured to each hot runner nozzle.

The injection molding apparatus further includes a plurality of mold cavities positioned to receive molten material from a plurality of side-pouring hot runner nozzles. Each mold cavity has at least one mold gate orifice, particularly having a third axis, the mold cavity comprising a mold core and a mold cavity wall, wherein an outer surface of the mold core and the mold cavity wall define a mold cavity space formed in the mold closed position to receive molten material.

The injection molding apparatus further includes a cavity heater at least partially surrounding each of the mold cavities and substantially coaxial with the axis of the mold core. The injection molding apparatus further includes a thermocouple associated with the mold cavity to directly or indirectly measure the temperature generated by the mold cavity heater.

In another refinement of the injection molding apparatus, the output melt channel portion has a second axis that is inclined relative to the first axis, and each hot runner nozzle includes a nozzle head portion, a nozzle body portion, and a nozzle tip portion, the nozzle further including at least one nozzle tip having a nozzle tip melt channel and an associated nozzle tip seal.

In another refinement of the injection molding apparatus, each nozzle further includes at least one nozzle tip having a nozzle tip melt channel and an associated nozzle tip seal, and the mold cavity has a mold gate opening for receiving the nozzle tip seal.

In another refinement of the injection molding apparatus, the cavity heater has a sleeve and a heater element connected to and secured to the sleeve.

Another improvement in an injection molding apparatus includes a controller connected to a nozzle thermocouple and a nozzle heater, and further connected to a cavity heater and a cavity thermocouple. The activation of the mold heater and the deactivation of the mold heater during an injection cycle are performed individually between each mold cavity in relation to quality information of each molded article ejected from the corresponding mold cavity at the end of each injection cycle.

Another improvement in the injection molding apparatus includes a second nozzle heater and a second nozzle thermocouple located near the mold gate at the lower end of the nozzle.

Another improvement in an injection molding apparatus includes a valve pin and a valve pin drive mechanism in each nozzle to control the flow of molten material in the cavity.

In another refinement of the injection molding apparatus, the mold heater is a thin film heater that includes a sleeve, a first electrically insulating layer deposited on the sleeve, an electronic component printed or etched on the first electrically insulating material, and a second electrically insulating material deposited on the electronic component. Some embodiments so designed are also referred to as thin film heaters.

In another refinement of the injection molding apparatus, the heater sleeve is constructed from two semi-annular sleeves, each having a separate heating element.

Drawings

The following description describes further advantages, features and possible applications of the invention in conjunction with the accompanying drawings.

In the drawings:

FIG. 1: a cross-sectional view of an exemplary injection molding apparatus according to the present invention for improving the known prior art design shown in FIG. 10;

FIG. 2: a cross-sectional view of another exemplary injection molding apparatus according to the present invention for improving the known prior art design shown in FIG. 9;

FIG. 3: FIG. 2 is an enlarged view of an injection mold region of the exemplary injection molding apparatus;

FIG. 4: FIG. 2 is a perspective view of an injection mold region of the exemplary injection molding apparatus;

FIG. 5 a: a front view of an exemplary cavity heater;

FIG. 5 b: FIG. 5a is a perspective view of an exemplary cavity heater;

FIG. 5 c: FIG. 5a is a top view of an exemplary cavity heater;

FIG. 5 d: details of the exemplary cavity heater of FIG. 5 a;

FIG. 6 a: a perspective view of a second exemplary cavity heater;

FIG. 6 b: FIG. 6a is an exploded view of an exemplary cavity heater;

FIG. 7 a: a front view of another exemplary cavity heater;

FIG. 7 b: FIG. 7a is a perspective view of an exemplary cavity heater;

FIG. 8 a: a perspective view of an injection mold region similar to FIG. 4;

FIG. 8 b: FIG. 8a is a cross-sectional view of the mold insert;

FIG. 8 c: FIG. 8b is a perspective view of the mold insert;

FIG. 9: flow of molten material in the prior art mold cavity; and

FIG. 10: the flow of molten material in another prior art mold cavity.

Detailed Description

Referring to FIG. 1, an injection molding apparatus 100 according to an exemplary embodiment of the present invention is shown. This exemplary embodiment relates to the flow of molten material. Apparatus 100 includes an injection manifold 10, a plurality of open-gated side-pouring hot runner nozzles 200 and a mold 62. Molten material (also referred to as melt) flows from the manifold through the nozzle 200 and into the mold cavity 66 in the mold 62. The flow of molten material in the cavity is similar to that shown in fig. 9, with the remainder of the invention being shown in detail in fig. 4-5-6-7-8.

Manifold 10 has at least one manifold input melt channel 11, a hot runner melt channel system 28, and a plurality of manifold output melt channels 13. Manifold 10 is heated by at least one manifold heater 30, which may be, for example, a fluid channel system that allows heated liquid to flow therethrough. The temperature of the manifold 10 may be determined by at least one manifold temperature sensor 31 (e.g., a thermocouple) that transmits a signal indicative of the manifold temperature to a control system (not shown). The controller controls the operation of the manifold heater 30 based on the data of the temperature sensor 31.

A plurality of side-pouring hot runner nozzles 200 are coupled to manifold 10. Each hot runner nozzle 200 includes a nozzle head 12, a nozzle body portion 21, and a nozzle tip portion 23. Each nozzle 200 further includes at least one nozzle tip 14 having a nozzle tip melt channel 3 therein, and an associated nozzle tip seal 16. The nozzle tip melt channel 3 forms at least part of the output melt channel portion.

A nozzle heater, indicated at 36, is secured to each hot runner nozzle 200 for heating the melt passing through the nozzle 200. Optionally, a plurality of nozzle heaters are secured to each hot runner nozzle 200. The nozzle heater 36 may be any suitable type of nozzle heater known in the art, such as an electrical resistance heater commonly used in hot runner injection nozzles.

A nozzle temperature sensor (e.g., a thermocouple, not shown) may be secured to each hot runner nozzle 200 to allow a control system (not shown) to determine the temperature of the melt within nozzle 200.

A mold, generally indicated at 62, includes first and second die plates 62a and 62b, and further includes a third die plate 62c and a fourth die plate 62 d. Third and fourth die plates 62c and 62d include a set of first and second die plate inserts, indicated at 62e and 62f, respectively. Together, inserts 62e and 62f cooperate with mold core 62g and sleeve 62h to define a plurality of mold cavities 66. In the illustrated embodiment, multiple sets of inserts 62e and 62f are provided, each set being associated with two mold cavities 66 and one hot runner nozzle 200. In another exemplary embodiment (not shown), each set of inserts 62e and 62f may be associated with a separate mold cavity and one hot runner nozzle 200. At the cavity walls of the insert 62f, a cavity heater 74 is provided for regulating the temperature of the walls of the cavity 66. Optionally, a second cavity heater 76 is provided at the mold core 62g for adjusting the surface temperature of the mold core 62 g.

A plurality of mold cooling channels 22 are provided in the mold 62 (specifically in the inserts 62e and 62f in the embodiment shown in fig. 1) to allow a coolant to flow therein for cooling the mold 62 to solidify the melt within the mold cavity 66.

The engagement of the nozzle tip 14 with the tip seal 16, and the engagement of the tip seal 16 with the mold gate opening 84, serve to fix the position of the nozzle 200 axially and laterally, and also serve to fix the lower end of the nozzle 200, so that when heated, the nozzle 200 will generally develop upward toward the manifold 10 during thermal expansion.

Fig. 2 shows another injection molding apparatus 100a according to an exemplary embodiment of the present invention. The apparatus 100a includes an injection manifold (not shown), a plurality of valve gated side-gating hot runner nozzles 200a and a mold 62 a. Each mold cavity 66a, 66b has two mold gate holes 67, and molten material is injected into the cavity through two side-pouring hot runner nozzles 200a via the two mold gate holes 67. Valve pin 33 is actuated by an electric drive 34. The flow of molten material within the cavity is similar to that shown in fig. 10, with the remainder of the invention being shown in detail in fig. 3-4-5-6-7-8.

Fig. 3 illustrates an enlarged view of an area of injection mold 62a of exemplary injection molding apparatus 100a of fig. 2. Tip end 14 of nozzle 200a is disposed at the bore of chamber 66a, which bore of chamber 66a is closed by valve pin 33. The mold 62a includes a mold insert 62o in which a mold cavity 66a is disposed. The mold core 62p is disposed within the mold insert 62 o. The mold insert 62a and the mold core 62p define a mold cavity 66 b. The cavity heater 74a surrounds the mold insert 62o and provides heat to the walls of the mold cavity 66 a. An optional cavity heater 76a is provided at the mold core 62p for providing heat to the surface of the mold core 62p and thus to the cavity 66 a. A plurality of mold cooling channels 22 are provided within the mold 62 to allow a coolant to flow therein for cooling the mold 62 to solidify the melt within the mold cavity 66. The sleeve of the heater 74a is thin to enable rapid cooling of the molten material after injection.

Fig. 4 illustrates a perspective view of a region of an injection mold of the exemplary injection molding apparatus of fig. 2. When the mold 62a is installed, the mold insert 62o receives the cavity heater 74a, and after installation, the cavity heater 74a surrounds the mold insert 62 o. The heater shown in fig. 4 is a thin film heater, which has only a small mass, which is advantageous for frequent temperature changes.

Fig. 5a shows a front view of an exemplary cavity heater 74, 74a, which includes an inner sleeve 75 and a flat heating element 78, which may be composed of a flat element or may specifically be printed or etched on the sleeve. The exemplary nozzle heaters 74, 74a also include thermocouples 79 for determining the temperature of the cavity heaters 74, 74 a. The sleeve 75 contains an insulating layer on its outer surface. A connector 81 is provided at the inner sleeve 75 for connecting the wiring 82 to a power source.

Fig. 5b shows a perspective view of the exemplary cavity heater 74, 74a, fig. 5c shows a top view of the exemplary cavity heater 74, 74a of fig. 5a, and fig. 5d shows details of the exemplary cavity heater 74, 74a of fig. 5 a. In detail, the inner sleeve 75, the outer sleeve 83 (containing an insulating layer on its inner surface), and the flat heating element 78 are described.

FIG. 6a shows a perspective view of a second exemplary cavity heater 74b that is different from the exemplary cavity heaters 74, 74a in that it comprises two semi-annular elements when installed around the mold insert 62 o. Fig. 6a shows an exemplary cavity heater 74b in a connected condition, and fig. 6b shows an exploded view of the cavity heater 74 b. The core heater 76 may have the same configuration as the cavity heaters 74, 74a or 74 b.

FIG. 7a shows a front view of another exemplary cavity heater 74c, which differs from the exemplary cavity heater 74a in that the cavity heater 74c has an opening 85. The opening 85 serves as a passage for the tip of the injection nozzle as shown in fig. 3. FIG. 7b illustrates a perspective view of the exemplary cavity heater of FIG. 7 a.

Fig. 8a shows a perspective view of a region of an injection mold similar to fig. 4, fig. 8b shows a sectional view of the mold insert of fig. 8a, and fig. 8c shows a perspective view thereof. The elements described are as described above. In fig. 8a, 8b and 8c, the cavity heater 74c is now coupled to the cavity insert 62 o.

While the foregoing description constitutes various embodiments of the invention, it will be understood that the invention is susceptible to further modifications and changes without departing from the fair meaning of the accompanying claims.

Claims

1. An injection molding apparatus (100) for laterally casting a moldable article, the injection molding apparatus (100) comprising:

-an injection manifold (10) having at least one manifold input melt channel (11) and a plurality of manifold output melt channels (13), said manifold (10) being heated by at least one manifold heater (30) controlled by at least one manifold thermocouple (31),

-a plurality of side-pouring hot runner nozzles (200, 200a) coupled to a manifold (10), each hot runner nozzle (200) comprising at least one input melt channel portion (15) having a first axis (17) and at least one output melt channel portion (39) having a second axis (38), the second axis (38) forming an angle with respect to the first axis (17);

-a first nozzle heater (36) and a first nozzle thermocouple (37) secured to each hot runner nozzle (200, 200 a);

-a plurality of mold cavities (66) positioned to receive molten material from a plurality of side-pouring hot runner nozzles (200, 200a), each mold cavity (66) having at least one mold gate orifice (67), the at least one mold gate orifice (67) having in particular a third axis (69), the mold cavities comprising mold cores (62g, 62h) and mold cavity walls (62k), wherein the outer surfaces (62m) of the mold cores and the mold cavity walls (62k) define a mold cavity space (66), the mold cavity space (66) being formed in a mold closed position for receiving molten material;

-a cavity heater (74) at least partially surrounding each mold cavity (66) and substantially coaxial with the axis of the mold core (77), said cavity heater (74) comprising a removable sleeve (75), a heating element (78) coupled to said sleeve (75) and a connector (81), wherein said cavity heater has an opening for passage of a top end of a respective hot runner nozzle;

-a thermocouple (71) associated with the mold cavity (66) to measure directly or indirectly the temperature generated by the mold cavity heater (74); and

-a controller connected to the first nozzle thermocouple and the first nozzle heater and further connected to the cavity heater (74) and the cavity thermocouple (71), wherein the activation of the mold heater (74) and the deactivation of the mold heater (74) or any change in temperature provided by the cavity heater (74) during an injection cycle is performed individually between each cavity in relation to quality information of each molded article ejected from the respective cavity at the end of each injection cycle.

2. Injection molding apparatus according to claim 1, wherein each hot runner nozzle (200, 200a) comprises a nozzle head portion (12), a nozzle body portion (21) and a nozzle tip portion (23), the nozzle further comprising at least two nozzle tips (14) and associated nozzle tip seals (16).

3. The injection molding apparatus of claim 2, wherein the mold cavity has a mold gate opening (84) for receiving and locking the nozzle tip seal (16).

4. Injection molding apparatus according to one of claims 1 to 3, comprising a second nozzle heater and a second nozzle thermocouple located near the mold gate at the lower end of the nozzle (200).

5. The injection molding apparatus of one of claims 1 to 3, wherein a valve pin (33) and a valve pin drive mechanism (34) in each nozzle (200) for controlling the flow of molten material within the mold cavity (66).

6. Injection molding apparatus according to one of claims 1 to 3, characterized in that the mold heater (74) is a thin film heater comprising a sleeve (75), a first electrically insulating layer deposited on the sleeve (75), an electronic component printed on the first electrically insulating material, a second electrically insulating material deposited on the electronic component.

7. Injection molding device according to one of claims 1 to 3, characterized in that the heater sleeve (75) is composed of two semi-annular sleeves (75a, 75b), each semi-annular sleeve (75a, 75b) having a separate heating element and a corresponding thermocouple.