Patent Application
20170182691
This invention is related to a hot runner injection molding apparatus. More specifically, this invention is related to a side, or edge gating hot runner nozzle.
Side or edge gating hot runner nozzles are known. The known concepts have shortcomings resulting from imbalances in heat distribution both in the apparatus and the melt.
A proper heat distribution is important for good functioning of a hot runner injection molding apparatus. Prior to manufacture, it is important, that all functional units of the apparatus have the necessary temperature as the design of the components is made with respect to the operating temperature of the apparatus. For example, only after the heating of the nozzle body and the respective thermal expansion, the nozzle tip fits sealing within the gate orifice. Accordingly, if the nozzle is not heated to the necessary temperature, leakage will occur.
Even more, due to manufacturing tolerances, there are areas where more heat is needed than in other areas, even of same components.
Therefore, there is a need for an improved control of the temperature within an injection molding apparatus.
The application proposes a hot runner injection molding apparatus comprising an injection molding manifold having an inlet melt channel and a plurality of outlet melt channels and a plurality of hot runner nozzles coupled to the outlet melt channels. Each hot runner nozzle includes a nozzle body defining a first nozzle body melt channel having a first axis. A nozzle tip housing is coupled to the nozzle body which includes at least two auxiliary melt channel portions each auxiliary melt channel portion has a second axis which is angled with respect to the first axis. At least two nozzle tips are arranged at the nozzle tip housing and in the area of each nozzle tip a nozzle tip heater is arranged, which is oriented substantially along the first melt channel.
In a further development, in the area of each nozzle tip heater of the hot runner injection molding apparatus, a thermocouple is arranged for controlling the heat output of the corresponding nozzle tip heater. This allows individual controlling of heat for each nozzle tip.
In a further development of the hot runner injection molding apparatus the nozzle tip heater transfers heat to the nozzle tips and to the melt channels. This allows heating of the nozzle tip area and the melt channels.
In a further development of the hot runner injection molding apparatus the nozzle tip housing includes at least one cutout which is arranged between two nozzle tips on the nozzle tip housing to lower the heat transfer in the area of the nozzle tip housing between the two nozzle tips. Thus the cutout assists the individual heat control at the nozzle tips. This provides a heat barrier between each tip to reduce the heat transfer between tips.
In a further development of the molding apparatus a heat enhancer is arranged within at least one cutout on the nozzle tip housing. The heat enhancer allows transfer of heat between two nozzle tip areas.
In a further development the molding apparatus comprises a plurality of mold cavities, wherein each mold cavity has at least one mold gate orifice. The mold cavity can have a mold core having a third axis that is parallel to the first axis.
In a further development, the nozzle body has a first main nozzle heater and a thermocouple. In particular separate heaters are provided for each nozzle tip separate thermocouples for each heater.
In a further development the molding apparatus comprises a controller to adjust the main nozzle body heater and each nozzle tip heater independently. This is in particular useful for the start-up of the injection and for full operation of the nozzle.
Further advantages, features and applications of the present invention will become apparent from the following detailed description taken in conjunction with the figures.
It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be clear to one skilled in the art when the present invention can be practiced without some or all of these specific details. In other instances, well-known features or processes may not be described in detail so as not to unnecessarily obscure the invention. In addition, like or identical reference numerals may be used to identify common or similar elements.
Reference is made to
Each hot runner nozzle 30 comprises a nozzle body 4 which in one axial direction of the nozzle body 4 fits at the manifold 1 in a way to allow molten material to flow from the outlet melt channel 22 into the first melt channel 32 disposed along a first axis 33 in the nozzle body 4 of the hot runner nozzle 30. In the opposite axial direction the nozzle body 4 penetrates the first mold plate 2 and is supported with its flange at the second mold plate 3.
Each hot runner nozzle 30 further includes a separate and removable nozzle tip housing 12 that is coupled to the nozzle body 4 via a sliding connector element 36 that provides for an axial movement of the nozzle tip housing 12 or of the nozzle body 4 to avoid any difficulties due to thermal expansion and to allow the disassembly of nozzle tip housing 12 and nozzle body 4.
Each nozzle tip housing 12 retains at least two nozzle tips 10 which are arranged in lateral openings of the nozzle tip housing 12. The number of nozzle tips 10 arranged at the nozzle tip housing is not limited to two nozzle tips 10. Depending on the size of the nozzle tip housing 12 and the nozzle tips 10, there can be 4, 6, 8, 10, 12 or even more nozzle tips 10 arranged in lateral openings at the nozzle tip housing 12. It is also possible to arrange an uneven number of nozzle tips 10 at the nozzle tip housing 12 as for example 3, 5, 7, 9 or more nozzle tips 10. The nozzle tips 10 extend partially outside of the outer surface of the nozzle tip housing 12.
As shown in
The injection molding cavities 15 are positioned along a third axis which here is parallel to the first axis 33. The lateral wall of a mold insert 8 includes a mold gate orifice 57 which is positioned adjacent a nozzle tip 10. Each nozzle tip 10 is surrounded by a nozzle seal element 21. The lateral wall section receives and locates the nozzle seal element 21 which serves for sealing the nozzle at the sealing section.
In
As shown in
The exemplary injection molding apparatus comprises at least one injection assembly 70 which comprises at least one upper assembly element 5 and a lower assembly element 9 which are designed to retain at least one mold cavity insert 8 and the nozzle tip housing 12. In
The nozzle body 4 of the hot runner nozzle 30 is located in a first fix position with respect to the manifold 1 and the nozzle tip retainer 12 of the hot runner nozzle 30 is located in a second fix lower position by the nozzle tips 10 and seal elements 21 connected to the nozzle tip housing 12. In case of an axial thermal expansion the nozzle tips 10 and nozzle seal elements 21, the nozzle 30 may be damaged due to a high stress. For this reason and to avoid problems the nozzle 30 is split in two parts that slide relative to the other, as is shown in
If a nozzle tip 10 or nozzle seal element 21 is damaged and needs to be removed from the nozzle 30, the invention provides a modular design approach. The two parts nozzle 30 provide for the nozzle body 4 to be located in a fix position relative to the manifold 1 and a mold plate 3 while allowing the nozzle tip housing 12 to be removed from the front side when the mold is in a stationary open position for servicing. As is shown in the Figures, the modular system comprises several injection assemblys 70 that include at least two openings 71 to locate at least two molding cavity inserts 8 in a tight, yet removable way. In
This injection assembly 70 comprises at least one upper assembly element 5 and a lower assembly element 9, several molding cavity inserts 8, a single nozzle tip housing 12 having at least two nozzle tips 10 and nozzle seal elements 21. With moving the plate 11 to the bottom side in
After the injection assembly 70 is removed from the corresponding mold plate 3, the lower assembly element 9, the nozzle tip housing 12 with the tips 10 and nozzle seal elements 21 can be removed. After that the molding cavity inserts 8 can be released from the nozzle tip housing 12 and nozzle tips 10 by lateral sliding. Next, the nozzle seal elements 21 and the nozzle tips 10 can be removed. The same steps but in reverse are used to assembly or to put back the nozzle head and the nozzle tips 10 in sealing contact with the mold gate orifices 57.
As is indicated by the arrow, each heat enhancer 26 can be adjusted in axial direction to determine the position of enhanced heat conduction. Depending on the design of the molded part and the process, it is also possible, that no heat enhancer 26 is used. Generally, the heat transfer between to nozzle tips 10 arranged side by side in the nozzle tip housing 12 rather needs to be avoided.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the claims.
