Method and apparatus for shaping a glass workpiece with minimal lubrication
An apparatus for shaping a workpiece made of glass using minimum lubrication is provided. The apparatus includes device for heating the workpiece, a shaping station with at least one forming tool for shaping the workpiece, and at least one spray nozzle for applying an oil as a lubricant onto the surface of the forming tool. The forming tool exhibits heat dissipation such that the temperature on the contact surface of the forming tool during the shaping process is kept below 300° C. The amount of oil dispensed by the spray nozzle per forming step and application instance is less than 0.1 g.
1. An apparatus for shaping a workpiece made of glass, comprising:
a heating device configured to heat the workpiece;
a shaping station with a forming tool, the forming tool having a contact surface that is configured to shape the workpiece, the forming tool is configured with a heat dissipation such that a temperature of the contact surface during shaping of the workpiece is below 300° C.; and
a spray nozzle configured to apply an oil as a lubricant onto the contact surface of the forming tool, wherein the spray nozzle provides a jacket gas spray emitted from the spray nozzle parallel to an oil-gas jet, and is configured and controlled, to dispense an amount of the oil that is less than 0.1 grams and provide a full-surface covering layer on the contact surface.
2. The apparatus of claim 1 , wherein the forming tool comprises an inner forming tool and an outer forming tool, the inner forming tool having an inner contact surface configured to shape an inner lateral surface of the workpiece, and the outer forming tool having an outer lateral surface configured to shape an outer lateral surface of the workpiece.
3. The apparatus of claim 2 , wherein the inner forming tool is a mandrel.
4. The apparatus of claim 1 , wherein the spray nozzle is configured and controlled to apply the oil to the contact surface in intermediate clock cycles of the shaping process.
5. The apparatus of claim 1 , wherein the spray nozzle is configured and controlled so as to provide a characteristic selected from a group consisting of: a directionally stable oil-gas jet, a vertical angle γ with the contact surface in a range from 0 to 60°, a horizontal angle α with the contact surface in a range from −85° to 85°, and any combinations thereof.
6. The apparatus of claim 5 , wherein the directionally stable oil-gas jet has an opening angle selected from a group consisting of: greater than 1°, in a range from 2 to 10°, and in a range from 2 to 6°.
7. The apparatus of claim 1 , wherein the heating device, shaping station, and spray nozzle are configured for the workpiece shaped as a tubular workpiece.
8. The apparatus of claim 1 , comprising a lateral spacing between the spray nozzle and the contact surface of 1 to 50 mm.
9. The apparatus of claim 1 , wherein the spray nozzle is a coaxial spray nozzle.
10. The apparatus of claim 1 , wherein the spray nozzle comprises a plurality of spray nozzles per forming tool.
11. The apparatus of claim 1 , wherein the spray nozzle is installed in the shaping station in a stationary manner or is installed in the shaping station a non-stationary manner so that the spray nozzle is driven towards or close to the forming tool in an intermediate clock cycle of the shaping process.
12. The apparatus of claim 1 , wherein the amount of oil is less than 0.01 grams.
13. The apparatus of claim 1 , wherein the spray nozzle is configured to apply the oil in a spraying process with a duration of less than 0.5 seconds.
14. The apparatus of claim 1 , wherein the temperature is below 250° C.
15. The apparatus of claim 1 , wherein the temperature is lower than an evaporation temperature and/or a flash point of the oil.
16. The apparatus of claim 1 , wherein the forming tool comprises a material exhibiting a thermal conductivity of at least 400 W/mK.
17. The apparatus of claim 1 , wherein the forming tool comprises copper.
18. The apparatus of claim 1 , further comprising a seat that holds the forming tool such that heat can be removed therefrom and/or supplied thereto through a heat exchange surface of the forming tool that is in direct mechanical contact with an associated heat exchange surface of the seat.
19. The apparatus of claim 18 , wherein the forming tool is releasably supported on the seat by a locking device.
20. The apparatus of claim 1 , wherein the forming tool comprises two pieces, and wherein the forming tool has an effective outer diameter that is adjustable by relative movement of the two pieces.
21. The apparatus of claim 1 , wherein the forming tool comprises a coolant passage configured to receive a cooling medium to cool the forming tool.
22. The apparatus of claim 1 , wherein the full-surface covering layer of the oil on the contact surface has a thickness of less than 750 μm.
23. The apparatus of claim 1 , wherein the full-surface covering layer of the oil on the contact surface has from one up to ten molecular monolayers of the oil.
24. An apparatus for shaping a workpiece made of glass, comprising:
a heating device configured to heat the workpiece;
a shaping station with a forming tool having a contact surface that is configured to shape the workpiece, the forming tool has a heat dissipation such that a temperature of the contact surface is below 300° C. during shaping of the workpiece; and
a spray nozzle configured to apply an oil onto the contact surface, the spray nozzle comprises a center with an oil supply line and air supply passages that generate an oil-air jet and comprises air jets external to the center that emit air in parallel to each other and to the oil and that impart directional stability to the oil so as to provide a full-surface covering layer of the oil on the contact surface with an amount of the oil that is less than 0.1 grams.