Valve jet printer with inert plunger tip
A valve jet printer includes a solenoid coil and a plunger rod having a magnetically susceptible shank. A first end of the shank and at least a portion of the shank are received within a bore of the solenoid coil. The printer also includes a nozzle including an orifice extending therethrough and a spring biasing a second end of the shank toward the nozzle. The second end of the plunger rod includes a tip formed of perfluoroelastomer (FFKM). The second end of the shank includes a cup-shaped cavity having a convex bottom and a circular side. The tip includes a concave base and an annular flange. In an assembled state, the concave base of the tip contacts the convex bottom of the cup-shaped cavity, and the end of the circular side opposite the convex bottom is rolled over the annular flange thereby securing the tip in the cup-shaped cavity.
1. A plunger rod for dispensing ink in a valve jet printer, the plunger rod comprising:
a shank having a first end and a second end at opposite ends thereof; and
a tip comprising a resilient, chemically inert material arranged at the second end.
2. The plunger rod of claim 1 , wherein the resilient, chemically inert material is a perfluoroelastomer.
3. The plunger rod of claim 2 , wherein the tip comprises:
perfluoroalkylpolyether in the range between about 5 wt % to about 8 wt %; and
less than 95 wt % perfluoroelastomer.
4. The plunger rod of claim 1 , wherein the tip further comprises one or more of polyamide fibers, polytetrafluoroethylene, and microcrystalline silica.
5. The plunger rod of claim 1 , wherein the tip further comprises one or more of the following:
less than 20 wt % polyamide fibers;
less than 20 wt % polytetrafluoroethylene; and
less than 15 wt % microcrystalline silica.
6. The plunger rod of claim 1 , wherein the tip is configured to contact and form a seal with a nozzle of the valve jet printer.
7. The plunger rod of claim 6 , wherein:
in response to a spring biasing the tip into contact with an orifice of the nozzle, the tip is configured to be deformed from its original shape to form a seal with the orifice of the nozzle; and
in response to the tip moving away from the orifice of the nozzle, the tip is configured to resume its original shape.
8. The plunger rod of claim 1 , wherein the shank is magnetically susceptible.
9. The plunger rod of claim 1 , wherein the tip has one or more of the following properties:
a Shore A hardness between 65 and 95;
a tensile strength of approximately 2,000 lb/in 2 ;
a maximum continuous service temperature of approximately 325° C.;
a 50% modulus of 15.5 MPa;
a tensile strength at break of 22.75 MPa;
an elongation at break of 75%; and
a compression set of 12% for 70 hours at 204° C., or 23% at 70 hours at 260° C.
10. The plunger rod of claim 1 , wherein the second end of the shank comprises a cup-shaped cavity having a convex bottom and a circular side.
11. The plunger rod of claim 1 , wherein the tip comprises a concave base and an annular flange configured to contact the second end of the shank.
12. A plunger rod for dispensing ink in a valve jet printer, the plunger rod comprising:
a shank having a first end and a second end at opposite ends thereof; and
a tip comprising a concave base and an annular flange configured to contact the second end of the shank.
13. The plunger rod of claim 12 , wherein the second end of the shank comprises a cup-shaped cavity having a convex bottom and a circular side, wherein in an assembled state of the tip and the second end of the shank, the concave base of the tip contacts the convex bottom of the cup-shaped cavity, and an end of the circular side opposite the convex bottom contacts the annular flange, thereby securing the tip in the cup-shaped cavity.
14. The plunger rod of claim 12 , wherein the tip is configured to contact and form a seal with a nozzle of the valve jet printer.
15. The plunger rod of claim 14 , wherein:
in response to a spring biasing the tip into contact with an orifice of the nozzle, the tip is configured to be deformed from its original shape to form a seal with the orifice of the nozzle; and
in response to the tip moving away from the orifice of the nozzle, the tip is configured to resume its original shape.
16. The plunger rod of claim 12 , wherein the shank is magnetically susceptible.
17. The plunger rod of claim 12 , wherein the tip has one or more of the following properties:
a Shore A hardness between 65 and 95;
a tensile strength of approximately 2,000 lb/in t ;
a maximum continuous service temperature of approximately 325° C.;
a 50% modulus of 15.5 MPa;
a tensile strength at break of 22.75 MPa;
an elongation at break of 75%; and
a compression set of 12% for 70 hours at 204° C., or 23% at 70 hours at 260° C.
18. The plunger rod of claim 12 , wherein the tip comprises a resilient, chemically inert material.
19. The plunger rod of claim 18 , wherein the resilient, chemically inert material is a perfluoroelastomer.
20. The plunger rod of claim 19 , wherein the tip comprises:
perfluoroalkylpolyether in the range between about 5 wt % to about 8 wt %; and
less than 95 wt % perfluoroelastomer.
21. The plunger rod of claim 18 , wherein the tip further comprises one or more of polyamide fibers, polytetrafluoroethylene, and microcrystalline silica.
22. The plunger rod of claim 18 , wherein the tip further comprises one or more of the following:
less than 20 wt % polyamide fibers;
less than 20 wt % polytetrafluoroethylene; and
less than 15 wt % microcrystalline silica.