This invention relates generally to the packaging and dispensing of solder paste and solder flux and more particularly to the packaging and dispensing of solder paste and solder flux in syringes.
It is generally known in the art to use a syringe stopper attached to a plunger handle in order to allow precise dispensing from a syringe and to allow for pulling back to create negative pressure to abruptly stop the flow of material. For example U.S. Pat. Nos. 4,215,701, 4,986,820, 8,740,854.
Some inventions have been published that include two part plungers, but with different designs and different utility than the invention presently disclosed. For example U.S. Pat. No. 9,532,742.
The invention disclosed solves the issue of a syringe of solder paste or solder flux only being suitable for use in either manual dispensing or pneumatic dispensing. In manual dispensing, if the ability to abruptly stop the flow of solder paste or solder flux from the syringe is required, a captive plunger that comes permanently affixed to the syringe stopper is used. This allows the syringe to be manually hand dispensed and the flow of solder paste or solder flux to be abruptly stopped when needed, but makes the syringe unusable for pneumatic dispensing.
If a syringe is setup for pneumatic dispensing, then the plunger is not affixed to the syringe stopper and when trying to manually dispense from a syringe using a non-affixed plunger, it is not possible to create negative pressure by pulling back on the syringe plunger, so the flow of solder paste or solder flux cannot be abruptly stopped. However, the loose plunger does allow pneumatic dispensing since the loose plunger can be removed from the syringe and the syringe can then be mated with a pneumatic dispensing adapter to apply positive or negative air pressure.
The nesting plunger tip invention disclosed herein allows the end user of a syringe to make the determination of which way they want to use the syringe, either hand dispensing, if they install the nesting plunger tip, or by pneumatic dispensing, if they leave the nesting plunger tip and plunger out of the syringe. The main advantage is that the end user can decide which way to assemble and use the nesting plunger tip depending on whether they want to do manual hand dispensing or pneumatic dispensing. This allows the manufacturer of the syringe to assemble and pack only one type of syringe, instead of two kinds which are normally required in order to serve both the manual hand dispensing and the pneumatic dispensing markets.
The nesting plunger tip 1 is able to fully nest within the syringe stopper 5 because the notch 2 allows air to escape as the nesting plunger tip 1 is inserted. Once the nesting plunger tip 1 is inserted, there is enough friction between the outside of the nesting plunger tip 1 and the inside of the syringe stopper 5 such that pulling back on the syringe plunger 6 causes the syringe stopper 5 to be pulled back as well, which creates a reduction in pressure on the contents of the syringe 4, which then stops the syringe 4 contents from dispensing.
To allow the syringe 4 to also be used for pneumatic dispensing, the plunger 6 can be pulled all the way out. When the plunger 6 is pulled out with sufficient force the nesting tip 1 will un-nest from within the syringe stopper 5. This then allows the back end of the syringe 4 to be attached to a pneumatic dispensing apparatus.
The present disclosure claims priority from U.S. provisional patent application No. 62/298,084 filed on Feb. 22, 2016, the contents of which are incorporated herein by reference.