WO2004041505A1

WO2004041505A1 - Shut-off device and method for hot runner gates

Info

Publication number: WO2004041505A1
Application number: PCT/IB2003/004984
Authority: WO
Inventors: Pawel Samotik; Stanislaw Samotik
Original assignee: Pawel Samotik; Stanislaw Samotik
Priority date: 2002-11-06
Filing date: 2003-11-05
Publication date: 2004-05-21

Abstract

A valve gating method for injection molding systems that eliminates many commonly used elements and replaces commonly used methods which control melt flow from the machine nozzle to form the molten plastic part. This gating method applies to two of the most commonly used molding systems: Hot and Insulator runners. The gate channels) of the hot runner or insulator runner systems is or are moved laterally (sliding) in any direction against the cavity gate(s), creating the opening and closing of the gate(s), and controlling melt flow into the cavity or cavities. The concept can also be reversed (or inverted) so that the cavity gate(s) can be moved laterally in any direction against the channel of the hot or insulator runner systems. This new design prevents generation of waste material and eliminates the formation of cold plugs.

Description

SHUT-OFF DEVICE AND METHOD FOR HOT RUNNER GATES

References Cited

U.S. PATENT DOCUMENTS 6,056,536 - May 02/2000 6,149,417 - Nov 21/2000

Field of Invention

This invention relates to methods of valve gating for use with plastic injection molds and systems. More specifically, this invention relates to laterally gating (stopping) the flow of molten materials from injection-molding systems such as hot and insulated runner systems into a mold cavity.

Background of the Invention

It is well known in the field of injection molding that some means must be provided to inhibit the flow of molten material into the cavity of a mold so that the mold may be cooled and opened to remove the molded part. There are two types of systems:

(NOTE: The elements 2, 4, 5, 6, 8, 9, and 10, which are a part of cold half 25 are identical for both Hot and Insulator Runner systems. Hence, the element numbers for these parts are the same for both Figure 1 and Figure 2.)

1. Hot Runner Molds (Figure 1)

In a hot runner mold, constantly heated plastic "melt" also known as molten material flows from the machine nozzle (17) through the balanced hot runner system (26), into a space defined on the cold half of the mold (4), in order to form the part. This space is between mold faces (5) and (6).

The opening in the mold cavity (in the cold half of the mold) is an aperture referred to as a "gate" (1 , 2) through which the "melt" (such as plastic) exits from the hot runner (1) to form the part. It is, of course, necessary to interrupt the flow through the gate to be able to open the mold and eject the molded part, as a part of an injection molding cycle. Earlier systems allowed the stopping of the "melt" entering the cavity by using a valve stem in this area. One of the earlier systems, U. S. Patent 6,056,536 (May 02,2000), would re-open the gate by using a third sliding element at the gate area between the molded part and the hot runner system.

A later system, U. S. Patent 6,149,417 (Nov.21, 2000), would re-open the gate by using a similar third sliding element at the gate area between the molded part and the hot runner system.

2. Insulated Runner Molds (Figure 2)

In insulated runner molds, an unheated or heated runner (16A, 31 A, 32A) is located between a machine nozzle (17) and a cold half of the mold (25), which contains mold cavity or cavities (4). During use, an outside portion of the plastic solidifies, creating the wall (31 B) and acts as a barrier for the flow of molten plastic. During use, molten plastic flows from machine nozzle (17) through the hot half of the mold (33), into a space defined on the cold half of the mold (4), in order to form the part. This space is between mold faces (5) and (6). The opening in the mold cavity (in the cold half of the mold) is an aperture referred to as a "gate" (2, 3) through which the "melt" (such as plastic) exits the insulated runner to form the part. It is, of course, necessary to interrupt the flow through the gate to be able to open the mold and eject the molded part, as a part of an injection molding cycle.

3. This Invention

This invention eliminates any sliding elements between gates 1 and 2 (in a hot runner system), or between gates 3 and 2 (in an insulator runner system). This is done by moving (sliding) either the cold half of the mold (25) against the hot half (26 or 33), or vice versa.

Detailed Description of this Invention

Molds generally have two methods of blocking the communication between the nozzle and the mold cavity.

First, in the 'thermal gating approach', the flow of the molten resin to the mold cavity is interrupted by freezing the mold gate area after the injection step, and prior to the opening of the mold.

Second, in the 'valve gating approach', a movable valve gate stem, located in the melt channel, is actuated to open and close the gate.

Both methods have several drawbacks. In 'thermal gating approach', the size of the mold gate is limited to small diameters to allow the cooling of the gate. Also, the operating temperature and pressure windows are limited to domains that do not cover a large number of applications. In the 'valve gating approach', the presence of the stem in the molt channel generates knit lines in the molten part. They cannot be used for several applications.

Figure 1 for the present invention shows the i iulti-cavity injection mold assembly with Hot

Runner System 100.

Machine nozzle 17 feeds molten material into channel 16A of locating ring 16, next to the manifold channel 12A and balanced channels 12B of manifold 12. This means that the distance from the machine nozzle to each molten part should be identical.

Manifold 12 is secured between manifold plates 11 and 14. Nozzle 17, locating ring 16 and/or manifold 12 includes heating elements 13 to maintain the proper temperature of the plastic material in the hot runner channels. Hot runner channels 12B feed the molten plastic material in through the channel (gate) 1. Next, the plastic material flows through channel

(gate) 2 where the molten plastic is pushed by the injection pressure between cavities 5 and cores 6 to form molten parts 4. The cooling channels (not shown) around mold cavities 4 are used to solidify the molten material. In some molds, heating channels may be used to heat the cold half of the mold for special molten plastics. The mold assembly components are well known in the industry of injection molding and are, therefore, not shown herein.

In the area of channel(s) 1, an insert could be implemented for resizing the diameters of the channel(s).

The support plate 15 is fixed to the injection machine's stationary platen 18 (injection side of the machine) and secures the locating ring 16 against machine nozzle 17.

In the present invention, the opening and closing of gates 1 and 2 is achieved by moving hot half 26 of the mold against cold half 25. or vice versa. The group of components: cavities 5, cores 6, core plate 8, stripper plate 9, and cavity plate 10 are part of an assembly and are referred to as cold half 25 of the mold. The group of components: manifold 12, manifold plates 11 and 14, and movement block 20 are all part of the assembly referred to as hot half

26 of the mold.

In the present invention the complete assembly of hot half 26 is moved in direction 19, vertical in this case. However (Figure 3), it can also move in any other axis, such as horizontally 19A, and in rotational direction 28 on the surface (Figure 1) 27 against cold half

25 of the mold.

Mold gate 1 has an axis parallel to the flow of molten material and to gate 2. The actuation mechanism moves the entire hot half 26 with inlet gate 1 in any direction, including the rotational direction 28 (Figure 3) against the center of rotation 29 during the opening and closing of the gate.

Movement blocks (Figure 1) 20 can be located on the side of mold 100, to open and close gates 1 and 2 in horizontal direction (Figure 3) 19A. To move 25 and 26 against each other, any method can be implemented, such as cams, cylinders, or blocks.

In the present invention, actuation piston 23 moves block 21 on sliding surface 22 in direction 24 to move hot half 26. The actuation mechanism can also be placed on cold half

25, if cold half 25 is moved against hot half 26. Figure 2 with the present invention shows multi-cavity injection mold assembly with

Insulated Runner System 200.

Machine nozzle 17 feeds a molten material to channel 16A and then to insulated runner main channel 32A and sub-channel(s) 31 A.

Plates 31 and 32, mold nozzle 3, and movement block 20 will be referred to as one unit, called insulated runner hot half 33.

Nozzle 17, locating ring 16 and insulated runner plates 31 and 32 may include a multitude of heating elements to maintain the proper temperature of the plastic material in the insulated runner system channels. The insulated runner channels 31 A feed the molten plastic material to mold nozzle 3, and flows through channel (gate) 2. The molten plastic is pushed by the injection pressure between cavities 5 and cores 6 to form the molten parts 4. Cooling channels around mold cavities 4 (not shown) are used to solidify the molten material. In some molds, heating channels may be used to heat the cold half of the mold for special molten plastics. The mold assembly components are well known in the industry of the injection molding and are, therefore, not shown herein.

In the area of channel(s) 3, an insert could be implemented for resizing the diameters of the channel(s).

Support plate 15 is fixed to the injection machine's stationary platen 18 (injection side of the machine) and secures the locating ring 16 against machine nozzle 17.

In the present invention, the opening and closing of gates 2 and 3 is achieved by moving insulated runner hot half 33 against the cold half 25 of the mold or vice versa.

The group of components: cavities 5, cores 6, core plate 8, stripper plate 9, cavity plate 10 are part of an assembly and will be referred to as cold half 25 of the mold. In the present invention, the complete assembly of insulated runner hot half 33 is moved in direction

(Figure 3) 19, vertical in this case. However, it can also move in any other axis, such as horizontally 19A, and in rotational direction 28 on surface (Figure 2) 27 against cold half 25 of the mold.

Mold gate 3 has an axis parallel to the flow of molten material and to gate 2. The actuation mechanism moves the complete insulated runner hot half 33 with inlet gate 3 in any direction including rotation (Figure 3) 28 against center of rotation 29 during the opening and closing of the gating process.

The movement blocks can be located on the side of mold system 200 (Figure 2), to open and close gates 1 and 2 of the mold in horizontal direction (Figure 3) 19A.

In the present invention (Figure 2), actuation piston 23 moves block 21 on sliding surface 22 in direction 24 to move hot half 33, and this entire mechanism is referred to as actuation mechanism 34. Actuation mechanism 34 can be placed anywhere on the mold including cold half 25, and can be designed in many ways and act in any direction. The present invention allows the possibility of integrating the actuation mechanism 34 in the opening and closing the mold.

Figure 3 in the present invention shows the movement 19 and 19A, and rotation 28 of the

Hot Half against Cold Half of the mold and reverse for Hot or Insulated runner systems. Figure 4 in the present invention shows an enlargement of a single cavity gate area. Figure

4A shows an opened valve gating system, in which gate 1 and gate 2 are aligned. Figure 4B shows a closed valve gating system, in which gate 1 and gate 2 are not aligned (displaced laterally).

Figure 5 in the present invention shows an insulator runner multi-cavity injection mold assembly with a different design of insulator runner hot half 36, in which hot half 36 can also move together with machine nozzle 17 as one unit in any direction, as previously indicated in other examples.

Machine nozzle 17 feeds molten material directly to insulated runner channel 32A.

Figure 5A shows an opened valve gating system, in which gate 3 and gate 2 are aligned.

Figure 5B shows a closed valve gating system, in which gate 3 and gate 2 are not aligned.

Figure 5C and 5D in the present invention shows an enlargement of the gating area for the

Insulated Runner system, where channels (gates) 3 and 2 (Figure 5C) are aligned showing the opened gate, and channels (gates) 3 and 2 (Figure 5D) are not aligned showing the closed gate.

Figure 6 in the present invention shows a hot runner multi-cavity injection mold assembly with a different design of insulator runner hot half 38, in which hot half 38 can also move together with machine nozzle 17 as one unit in any direction, as previously indicated in other examples.

Machine nozzle 17 feeds molten material directly to hot runner channel 37A.

Figure 6A shows an opened valve gating system, in which gate 1 and gate 2 are aligned.

Figure 6B shows a closed valve gating system, in which gate 1 and gate 2 are not aligned.

Figure 7 in the present invention shows a single or multi-cavity injection mold assembly

(300) with the possibility of injecting one or many molten parts 4 with two or more plastic materials, in thjs case X and Y. More materials, however, can be implemented into the system.

The arrangement of this invention can be used with hot or insulated runner systems (100,

200 and/or 400).

Figure 7A shows a closed gate for plastic material X and Y, whereby the plastic material is blocked and does not enter through any gate to form molten part 4.

Figure 7B shows an opened gate for plastic material X, which is pushed through gate 1X to form molten part 4. The volume of plastic X is established during the molding process and depends on wall thickness 39 of molten part 4.

Figure 7C shows an opened gate for plastic material Y, which is pushed through gate 1Y to form molten part 4. The volume of plastic material Y will be determined during the molding process. The amount will be dependant on the volume of plastic material X. Plastic material

Y will push the plastic material X onward creating thin walls 39 against core side 6 and cavity side 5 to form another layer (40) of plastic material.

Figure 8 in the present invention shows the multi-cavity injection mold assembly 400, referred to as a stack mold with two cold halves 40 and 41. First, cold half 40 is assembled on the injection side of the machine. Then, cold half 41 is assembled on the clamp (or moving side) of the injection machine. Hot runner 42 or insulated runner 43 is assembled in the center of the mold.

The opening and closing of gates and the flow of the plastic material to gates is controlled by moving hot runner 42 or insulated runner 43 in direction 51 , vertically (as shown) or horizontally (not shown).

Figure 9 in the present invention shows offset multi-cavitv injection mold assembly (500).

This arrangement allows the injection of one or more materials using the hot runner or insulated runner systems where gates 52 and 53 are offset by distance 54. These multiple gates can be opened or closed in direction 55. This invention will allow longer parts to be produced.

DRAWINGS

Brief Description of the Drawings for this Invention

The present invention will be understood when taking into consideration the accompanying drawings, whereby:

Figure πo.1 is a section view of a multi-cavity hot runner system mold, named as element

100.

Figure no. 2 is a section view of the multi-cavity insulator runner system, named as element

200.

Figure no. 3 is a plan view of the multi-cavity, hot runner and insulated runner mold systems, showing additional rotational possibility for the closing and opening of the gate(s).

Figure no.4 is a section view of the single-cavity hot runner mold system, showing an enlarged view of the closing and opening of the gate.

Figure no. 5 is a section view of the multi-cavity insulator runner system, showing the possibility for the closing (Figure 5B) and opening (Figure 5A) of the gate.

Figure 5C and 5D is a section view of the single-cavity insulated runner mold system, showing an enlarged view of the closing and opening of the gate.

Figure no. 6 is a section view of the multi-cavity hot runner system, showing the possibility for the closing (Figure 6B) and opening (Figure 6A) of the gate.

Figure no. 7 is a section view of a single or multi-cavity system (named as element 300), showing the additional possibility of lateral movement for the closing and opening of the gate for multiple materials.

Figure no.7A shows the closed gates for two materials.

Figure no.7B shows the opened gate for only one material X in the two materials gating method.

Figure no.7C shows the opened gate for material Y in the two materials gating method.

Figure no. 8 is a section view of the multiple cavity or cavities, showing the opening and closing of the gate by laterally moving the center portion in the stack mold (named as element 400).

This drawing relates to single or multi-material systems.

Figure no. 9 is a section view of multiple cavity system (named as element 500) in accordance with the present invention, showing the opening and closing of the gate by laterally moving the offset-system in single or stack molds.

This drawing relates to single or multi-material systems.

Figure no. 10 is the drawing which should accompany the abstract.

Claims

Claim no. 1

The present invention provides a simpler and more effective gating method for operating a hot runner system (Figure 1, 3, 4, 6, 8 and 9) and insulator runner system (figure 2, 3, and 5) which are easier to manufacture, operate and service.

Claim no. 2

Another objective of the present invention is to eliminate moving components at the gate area(s). inside the hot or insulator runner systems.

Claim no. 3

Another objective of the present invention is to provide the gating method to secure the opening and closing of the gate(s).

Claim no. 4

Another objective of the present invention is to provide a gating method wherein substantially no material is diverted from the stream of molten material during the injection process.

Claim no. 5

Another objective of the present invention is to provide a simpler and more effective gating method for single material and multi-material molds.

Claim no. 6

Another objective of the present invention is to provide a simpler and more effective gating method of molding plastic articles with substantially no gate vestige.

Claim no. 7

Another objective of the present invention is to provide a simpler and more effective gating method of molding plastic articles with no crvstallinitv.

Claim no. 8

Another objective of the present invention is to provide a simpler and more effective gating method for molding plastic articles with no knit lines.

Claim no. 9

Another objective of the present invention is to provide a simpler and more effective gating method of molding plastic articles with a good Quality gate area. Claim no. 10

The present invention may have one or more injection gates (injection points), which guide at least one stream of molten material desirably, having a tubular flow pattern, towards one or more cavity spaces, for a single or multi-layered part.

Claim no. 11

Another objective of the present invention is to provide a simpler and more effective gating method of molding plastic articles that can consist of one or more materials by simply moving the inlet gate against he cavity gate, or vice versa.

Claim no. 12

Another objective of the present invention is to provide a simpler and more effective gating method of molding plastic articles made from one or more materials with offset cavity gates (Figure 9).

Claim no. 13

Another principle objective of the present invention is to provide a simpler and more effective gating method of molding plastic articles made from one or more materials bv moving the cold half against the hot half of the mold, or vice versa.

The hot half of the mold can be moved with or without the machine nozzle against the cold half of the mold.

Claim no. 14

Another principle objective of the present invention is to provide a simpler and more effective gating method of molding plastic articles by moving the center portion of the stack mold for hot and insulator runner systems.

Claim no. 15

Another objective of the present invention is to provide a simpler and more effective gating method of molding plastic articles that can consist of one or more materials by simply moving (sliding) the Hot Half of the mold against the Cold Half of the mold, or vice versa.