Patent Application
20210162492
The present invention relates to a back spray system for an injection piston used in a die casting machine. More particularly, the present invention comprises a system to sufficiently lubricate the interior of the die casting sleeve and plunger tip from the die mold to a pouring port.
In die casting, molten metal, such as aluminum, is poured into a shot sleeve through a pouring port in the shot sleeve. A predetermined amount of the molten metal is transferred into a shot sleeve for insertion by an injection piston into a die cavity forming a casting, the metal is cooled and the casting removed from the die. The injection piston, consisting of a shot rod and a plunger tip, is axially moved or extended into the shot sleeve to “shoot” the molten metal into the die cavity. It is necessary to both lubricate and cool the plunger tip and the shot rod due to the high temperatures, the presence of molten metal on the plunger tip and the plunger rod, and the friction between the plunger tip and the shot sleeve.
A shot system is prone to many different problems. Excessive wear and poor lubrication frequently occur between the enlarged plunger tip and the shot sleeve, as well as dripping and wasting of lubricant used to minimize wear. Lubrication of these contiguous surfaces has heretofore suffered from inefficiency and plugging of the lubricating lines and the lubricating holes causing excessive wear and parts fatigue. The cleaning of these lubricating holes or ports has been difficult and time consuming, while excess emission lubrication and improper lubrication creates a smoke emission problem during die casting operation.
In attempting to overcome lubrication problems, various lubricating systems have been developed. However, it is difficult to cause the lubricant to spread around the peripheral surfaces from the clearance between the end face of the shot sleeve and the end face of the injection piston, causing an early abrasion or fouling of portions that are not covered by the lubricant.
It is an object of an aspect of the present invention to provide, for example, a system that allows lubricant to get a proper place in a shot sleeve.
A back spray system in accordance with an aspect of the present invention is a back spray system for lubricating a shot sleeve of a die casting machine, including: a shot sleeve; an injection piston having a plunger tip and a shot rod connected to the plunger tip; a groove surrounding the shot rod; and a collar surrounding the groove; the shot rod having a shot rod hole through the length of the shot rod; the groove having at least one groove hole connected to the shot rod hole; the collar having a predetermined number of collar holes in communication with the groove and positioned circumferentially about the collar, and lubricant, having been supplied to the shot rod hole, flowing through the at least one groove hole into the groove, and then being released from the groove through the collar holes to a space between the plunger tip and the shot sleeve.
An injection piston in accordance with an aspect of the present invention is an injection piston used in combination with a shot sleeve, including: a plunger tip; a shot rod connected to the plunger tip; a groove surrounding the shot rod; and a collar surrounding the groove; the shot rod having a shot rod hole through the length of the shot rod; the groove having at least one groove hole connected to the shot rod hole; the collar having a predetermined number of collar holes in communication with the groove and positioned circumferentially about the collar, and lubricant, having been supplied to the shot rod hole, flowing through the at least one groove hole into the groove, and then being released from the groove through the collar holes to a space between the plunger tip and the shot sleeve.
An aspect of the present invention allows lubricant to get to a proper place in a shot sleeve.
Having described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale.
The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather these embodiments are provided so that this disclosure will be through and complete and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to the elements throughout.
It is therefore the general object of one or more embodiments of the present invention to provide a lubricating system to apply lubricant as far forward in the shot sleeve as possible. Another object is to sufficiently atomize lubricant to cover all the interior of the shot sleeve from die mold to pouring port.
There is provided back spray system comprising an injection piston having a plunger tip and a shot rod with a gun drilled hole through the length of the rod connecting a lubricant supply to a collar located behind the plunger tip.
The collar has a predetermined number of holes or ports positioned circumferentially about the collar sized and positioned to dispense a precise and uniform amount of lubricant and air to the space between the plunger tip and the shot sleeve. The number of holes depends on the circumference of the shot rod. Under the collar is a channel with two drilled holes connected to the shot rod hole that extends the length of the shot rod.
When the injection piston is in use a lubricant and air mixture travels through the shot rod holes to the collar where the mixture is released or sprayed out to thoroughly cover the shot sleeve and plunger tip and apply lubricant to the far forward portion of the shot sleeve.
Other objects features and advantages of the invention will be apparent to those skilled in the art from the following detailed description taken in conjunction with the drawings.
[Configuration of Die Casting Machine]
Turning now to
In
[Description of Back Spray System]
The lubrication problem has been overcome by the back spray system of the present invention one embodiment of which is shown in
Inside shot sleeve 20 the back spray system will apply lubricant to the inner periphery of the shot sleeve 20 so that as the plunger tip 26 is pushed into and out of the shot sleeve 20 the lubricant coats the entire area. Any of the conventional lubricating oils may be used as the lubricant. To get the lubricant to the proper place a shot rod hole 32 is drilled the length of the shot rod 24 to right behind the forward end of the shot rod 24. The size of the shot rod hole 32 will vary depending upon the size of the shot sleeve 20 and injection piston 23 and to an extent the lubricant used. Typically the shot rod hole 32 is from approximately 6.5 mm to about 19.05 mm (about ¼ to ¾ inch) in diameter. The lubricant is supplied under pressure to the rear end of the shot rod 24 through equipment known to those skilled in the art.
The plunger tip 26 is connected, such as a screw connection, by threads 34 to the end of shot rod 24. Behind the plunger tip 26 is a recessed groove 36. In the examples of
In the embodiment shown in
As is clear from
In an example of practicing this invention, a shot rod 24 was drilled with one 7.94 mm ( 5/16 inch) diameter shot rod hole 32 the length of the shot rod 24 to push a lubricant/air mixture to a channel with two 7.94 mm ( 5/16 inch) gun drilled groove holes 38 in a channel covered by the collar 30 that has eight (8) collar holes 40 drilled to disperse the lubricant/air mixture. The lubricant/air mixture was pressurized in the shot rod 24 inside the shot rod hole 32 then pushed into the groove 36 behind the collar 30, then pushed out of the eight collar holes 40 under pressure as the shot rod 24 retracts the length of the shot sleeve 20. The lubricant/air mixture was pressurized through the shot rod hole 32 to efficiently atomize lubricant, while the shot rod 24 was pulled back, the atomized spray delivered the lubricant the length of the shot sleeve 20 and draw.
In a conventional example the amount of lubricant/air mixture spraying down the porthole was 2 to 2.5 ml per shot. After the back spray system of this invention was installed the usage dropped to 0.75-1.0 ml per shot. During a two month time period there were 11 plunger tip 26 changes with the conventional method of spraying down the porthole and 4 plunger tip 26 changes with the back spray system. Shot sleeve 20 life was also improved. Decreased consumption of lubricant was obtained as well as extended plunger tip 26 and shot sleeve 20 life. Decreased porosity of die cast parts was also observed.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
The contents of Provisional Application U.S. Ser. No. 62/703,564 filed Jul. 26, 2018, on which the present application is based and benefit claimed under 35 U.S.C. § 119(e), in incorporated by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/028761 | 7/23/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62703564 | Jul 2018 | US |
