Injection nozzle for a metallic material injection-molding machine
Inactive Publication Date: 2006-09-19
HUSKY INJECTION MOLDING SYST LTD
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- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Benefits of technology
[0009]Another object of the invention is to provide, in a metallic material injection machine, an injection nozzle that may move relative to the sprue bushing without losing sealing at the interface between the nozzle and the bushing.
[0013]The invention provides an improved nozzle and sprue bushing for a metallic material injection molding machine. The sprue bushing has a cylindrical surface and the nozzle an annular portion. The annular portion snugly fits within the cylindrical surface to provide a sealing engagement between the surface and the portion when the nozzle engages the bushing. The surface and the portion are of sufficient length to permit limited axial movement therebetween without a loss of sealing between them. The actual seal may be provided by the close fit between the bushing and the nozzle or by slight seepage of the metallic material between the surfaces where it freezes and provides the necessary seal.
[0014]The invention provides, in a metallic material injection molding machine, an injection nozzle joined to an injection barrel of the injection molding machine, a stationary platen holding a portion of a mold and a sprue bushing mounted in the mold. The nozzle engages the sprue bushing when the metallic material is injected through the sprue bushing into the mold. The nozzle has a spigot portion which extends into a channel in the sprue bushing. An outer periphery of the spigot fits into the inside surface of the channel so as to create a seal between the surface and the periphery of the spigot or enable the metallic material to create and seal and thereby prevent loss of metallic material through the interface between the nozzle and the sprue bushing during an injection cycle.
Problems solved by technology
However, it has been discovered that even when the highest acceptable force is applied at the interface between the nozzle and the sprue bushing, it is insufficient to prevent some parting at the interface.
This parting at the interface creates a build up of injection material on the surfaces of the interface with the ultimate result that the interface may fail to seal and permit the leakage of the injected material with sometimes catastrophic results.
Unfortunately, it has been discovered that it is virtually impossible to provide adequate clamping force to prevent separation between the nozzle and the sprue bushing when injecting metallic material, particularly material in a thixotropic state, because such very high pressures are involved and the reactionary and dynamic forces reach such high and relatively uncontrollable levels that separation eventually occurs.
Method used
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[0022]Referring to FIGS. 1 and 2, the injection assembly 10 includes an injection barrel 11 having an extruder screw 12 for feeding thixotropic metallic material toward a nozzle 13. Carriage cylinders 14 move the assembly 10 toward and away from the stationary platen 15 and clamp the assembly 10 into place with the nozzle 13 in operative association with a sprue bushing connected to a mold which is mounted between stationary platen 15 and a movable platen (not shown) in a manner well-known in the art. Tie-bars are connected to the stationary platen 15 at the four corners of the platen 15 as indicated at 17 and to the frame of the injection machine when the nozzle is in the injection position in a manner that is well-known in the art. The tie-bars ensure that the pressure is applied uniformly to the platen 15 and the mold mounted thereon in a manner that is also well-known in the art.
[0023]To enable injection of metallic material into a mold, the carriage cylinders 14 move the barrel...
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Abstract
In metallic material injection molding machines, the connection between the injection nozzle and the sprue bushing has tended to leak metallic material. To overcome this problem, the nozzle has been modified to have a projecting portion or spigot that extends into a mating portion of the sprue bushing to form a seal between the respective portion walls. The nozzle and sprue bushing can move axially with respect to one another without loss of sealing whereas with the prior designs any separation between confronting annular surfaces on the sprue bushing and the nozzle would result in a loss of sealing and leakage.
Description
BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention is directed to an improved injection nozzle for a metallic material injection-molding machine and particularly a metal alloy injection machine.[0003]2. Related Prior Art[0004]In metallic material injection technology the facing surfaces between the nozzle and the sprue bushing on the mold have been machined so as to be compliant with one another and designed so as to have substantial surface contact. In this design it was assumed that the carriage cylinders could apply sufficient pressure to the nozzle to prevent it from parting contact with the sprue bushing. However, it has been discovered that even when the highest acceptable force is applied at the interface between the nozzle and the sprue bushing, it is insufficient to prevent some parting at the interface. This parting at the interface creates a build up of injection material on the surfaces of the interface with the ultimate result that the...
Claims
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Patent Timeline
Login to View More IPC IPC(8): B22D17/04B22D17/00B22D17/08B22D27/09B22D17/20B22D17/22
CPCB22D17/007B22D17/2015B22D17/00
InventorKESTLE, MARTIN R.MANDA, JAN MARIUS
OwnerHUSKY INJECTION MOLDING SYST LTD