Method and apparatus for the hot forming of glass workpieces, and hot-formed glass container
An apparatus for producing a glass workpiece includes: a device configured to heat a glass until it softens; an inner molding tool configured to mold inner lateral surfaces of the workpiece; an outer molding tool configured to mold outer lateral surfaces of the workpiece, the outer molding tool having a shaping roller with a shaping surface; an accommodating device configured to accommodate the shaping roller, the shaping roller being mounted in a freely rotatable manner in the accommodating device and is fixable during a shaping process by a lockable locking device, the shaping roller being locked with a releasable connection such that the shaping roller can be released and rotated through an angle α in the locking device between individual shaping processes; and an apparatus configured to apply a lubricating oil to the shaping surface of the shaping roller and having an outlet opening configured to dispense the lubricating oil.
1. A method for molding glass, comprising the following steps:
a) heating a glass workpiece until the glass of the workpiece softens;
b) molding the workpiece with a molding tool, wherein the workpiece is positioned on an inner molding tool and is rotated about an axis of rotation and outer lateral surfaces of the workpiece are molded by an outer molding tool, wherein the outer molding tool has at least one shaping roller with at least one shaping surface and the at least one shaping roller is fixed to an accommodating apparatus by a releasable locking device, such that, during the molding, a relative movement is executed between the at least one shaping surface and the workpiece, and at least a part of the at least one shaping surface that comes into contact with the workpiece during the molding is covered with an oil as lubricant; and
c) releasing the locking device, rotating the at least one shaping roller through an angle α, repeating steps a) and b), and fixing the at least one shaping roller again such that, when steps a) and b) are repeated, a different part of the at least one shaping surface of the at least one shaping roller comes into contact with the workpiece, wherein, during one of steps a) to c), oil is applied to a part of the at least one shaping surface that is not in contact with the workpiece at the time the oil is applied.
2. The method of claim 1 , wherein the workpiece comprises a tubular workpiece.
3. The method of claim 1 , wherein the outer lateral surfaces of the workpiece are molded with the aid of a shaping roller with a round or polygonal cross section in a center plane perpendicular to an axis of rotation of the shaping roller with the round or polygonal cross section.
4. The method of claim 1 , wherein, in each cycle of steps a) to c), lubricating oil is applied to a part of the at least one shaping surface of the shaping roller with a drip-feed lubricator.
5. The method of claim 1 , wherein, during the oil application, 0.01 to 0.1 g of oil are applied.
6. The method of claim 1 , wherein heat is dissipated from the at least one shaping roller during the shaping process by heat conduction.
7. The method of claim 1 , wherein the outer molding tool is flushed with a cooling medium, during the molding.
8. The method of claim 1 , wherein the part of the at least one shaping surface that is in contact with the workpiece during the molding is cooled by a gas stream.
9. The method of claim 1 , wherein the at least one shaping surface of the at least one shaping roller exhibits a temperature of at most 250° C. during the molding.
10. The method of claim 9 , wherein the at least one shaping surface of the at least one shaping roller exhibits a temperature of at most 180° C. during the molding.
11. The method of claim 10 , wherein the at least one shaping surface of the at least one shaping roller exhibits a temperature of at most 100° C. during the molding.
12. The method of claim 1 , wherein, in step c), the at least one shaping roller is rotated through an angle α in the range from 1 to 60°.
13. The method of claim 12 , wherein the angle α is in the range from 2° to 10°.
14. The method of claim 1 , wherein, after step c), a step d) cleaning the at least one shaping roller takes place, wherein the cleaning step d) takes place, at the earliest, at least one of after 10,000 repetitions of steps a) to c) or after a down time of at least 4 hours.
15. The method of claim 1 , wherein, after step c), a step e) cleaning the at least one shaping roller takes place, wherein a part of the at least one shaping surface of the at least one shaping roller is cleaned, wherein step e) takes place during a repetition of steps a) to c) with a new workpiece.
16. The method of claim 15 , wherein lubricating oil is applied between step e) and the repetition of step a) with the new workpiece.
17. The method of claim 1 , wherein the angle α corresponds to an angle of the at least one shaping surface.
18. The method of claim 1 , wherein the lubricating oil is applied to a cold region of the at least one shaping roller that is not in contact with the workpiece, the cold region having a lower temperature than the part of the at least one shaping surface that contacts the workpiece.
19. The method of claim 1 , wherein the lubricating oil is applied by a lubricator having an outlet opening from which the lubricating oil is applied, the lubricator being positioned such that the outlet opening and the molding tool are arranged at an angular distance of at least 45° about an axis of rotation of the workpiece.