METHOD AND APPARATUS FOR PRODUCING GLASS PRECURSORS AND GLASS PRODUCTS

Abstract

A method and apparatus for producing glass products from tubular glass precursors is provided. In particular, a method and apparatus for separating tube glass into sized glass tube portions, produced glass tube portions, glass precursor portions, or glass product portions, and their use as pharmaceutical packaging are provided. The tube glass or the glass precursor or the glass product is provided with filaments along predetermined breaking planes. The filaments extend obliquely to the local wall radius and allow for clean separation of the tube glass or the glass precursor or the glass product.

Claims

1. A method for producing glass precursors and glass products, comprising the steps of: providing a glass tube or a tubular glass precursor; and laser-based irradiation of the glass tube or the tubular glass precursor with focused radiation to produce filaments in a separation plane of the glass tube or the tubular glass precursor, wherein the laser-based irradiation step comprises focusing the focused radiation at an oblique irradiation angle deviating from a perpendicular to a local surface of the glass tube or the tubular glass precursor.

2. The method of claim 1, further comprising inducing mechanical or thermal stress in the separation plane of the glass tube or the tubular glass precursor to create a fracture surface along the separation plane to separate sized portions from the glass tube or the tubular glass precursor.

3. The method of claim 1, further comprising rotating the glass tube or the glass tube precursor and the focused radiation relative to each other such that the focused radiation is incident on the glass tube or the tubular glass precursor in the separation plane.

4. The method of claim 1, wherein the oblique irradiation angle is in a range from 75 to 89.5.

5. The method of claim 1, wherein the glass tube or the glass tube precursor has a diameter in a range from 3 mm to 50 mm, and wherein, due to the oblique irradiation angle, the focused radiation has an offset relative to a local radial direction in a range from 0.1 mm to 3 mm, measured on the surface of the glass tube or the tubular glass precursor.

6. An apparatus for producing tubular glass precursors or glass products, comprising: a feeding device for a glass tube or a glass precursor; a laser-based irradiation device including focusing optics, the laser-based irradiation device being configured to generate focused radiation along a separation plane and at an oblique irradiation angle relative to a local surface of the glass tube or the glass precursor; a guiding device configured to guide the focusing optics along the separation plane at a distance and in the oblique irradiation angle with respect to the local surface; and a take-off device configured to separate sized glass tube portions or glass precursors at the separation plane.

7. The apparatus of claim 6, wherein the guiding device is configured for orbital revolution of the laser-based irradiation device around the glass tube or the glass precursor.

8. The apparatus of claim 6, wherein the laser-based irradiation device and the guiding device are configured for moving concomitantly along a feeding direction of the glass tube or the glass precursor.

9. The apparatus of claim 6, wherein the feeding device forms part of a producing apparatus or shaping apparatus for the glass tube or the glass precursor.

10. The apparatus of claim 6, wherein the laser-based irradiation device comprises a laser, the focusing optics, and a hollow glass fiber connecting the laser and the focusing optics, and wherein the guiding device forms part of a robot which causes the focusing optics to be effective at the distance and the angular orientation relative to the local surface in the separation plane around the glass tube or the glass precursor.

11. The apparatus of claim 10, wherein the focusing optics is accommodated in a guide head that includes a distance sensor and a scanning sensor, the distance sensor being configured to determine the distance to the local surface, the scanning sensor being configured to determine a position of the sized glass tube portions or glass precursors.

12. The apparatus of claim 6, wherein the laser-based irradiation device comprises a rotatable scanner head with beam guidance to the focusing optics, the beam guidance being arranged on an inner surface of a mirror that defines an annular space through which the tube glass or the glass precursor extends.

13. The apparatus of claim 12, wherein the mirror has portions arranged along a helix.

14. The apparatus of claim 12, wherein the mirror has portions configured as imaging optics.

15. The apparatus of claim 12, further comprising a plurality of rotatable scanner heads arranged around the glass tube or the glass precursor.

16. A tubular glass precursor or glass product, comprising a tube glass including filaments, the filaments being provided in a separation plane and extend obliquely to local wall radii.

17. The tubular glass precursor or glass product of claim 16, wherein the tube glass is in a form selected from a group consisting of an ampoule, a cartridge, and a syringe body.

18. The tubular glass precursor or glass product of claim 16, wherein the filaments provide a breaking point along the separation plane for later separation.

19. A glass tube portion or glass precursor portion, comprising a fracture surface produced at an end comprising broken open filaments that extend obliquely to local wall radii.

20. The glass tube portion or glass precursor portion of claim 19, wherein the broken open filaments are arranged with a spacing from each other in a range from 2 m to 15 m.

21. The glass tube portion or glass precursor portion of claim 19, wherein the broken open filaments belong to two or more filament areas distributed around a circumference of the glass tube or the glass precursor portion.

22. The glass tube portion or glass precursor portion of claim 21, further comprising unaffected areas between the two or more filament areas have an extent of at least 50 m measured in the circumferential direction of the product.

23. The glass tube portion or glass precursor portion of claim 21, wherein the two or more filament areas comprise up to twelve areas.

24. The glass tube portion or glass precursor portion of claim 21, wherein the two or more filament areas occupy at least 8% of the circumference.

25. The glass tube portion or glass precursor portion of claim 21, further comprising at least one predetermined breaking plane with filaments extending obliquely relative to the local radius.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Exemplary embodiments of the invention will now be described with reference to the drawings, wherein:

[0037] FIG. 1 is a first schematic view of an irradiation device for producing filaments in a glass tube;

[0038] FIG. 2 is a second schematic view of an irradiation device comprising a rotatable scanner head;

[0039] FIG. 3 is a third schematic view of an irradiation device with a helical mirror;

[0040] FIG. 4 is a fourth schematic view of an irradiation device with imaging optics annular mirror;

[0041] FIG. 5 shows an irradiation device with glass tube portion separation device;

[0042] FIG. 6 is a geometric diagram illustrating the orientation of the irradiation device relative to the glass tube to be processed;

[0043] FIG. 7 is a schematic view of a guide head with integrated irradiation device;

[0044] FIG. 8 illustrates irradiation optics at a decentered position with respect to the local surface of a glass tube;

[0045] FIG. 9 shows an enlarged portion of a fracture surface of a glass tube with obliquely extending filaments;

[0046] FIG. 10 shows an enlarged section of FIG. 9;

[0047] FIG. 11 shows a further enlarged section of FIG. 10; and

[0048] FIG. 12 shows a glass tube portion with filament areas.

DETAILED DESCRIPTION

[0049] FIG. 1 shows an apparatus for preparing the separation of tube glass into sized glass tube portions. The apparatus comprises a feeding device 1 for glass tube 2, a laser-based irradiation device 3 for generating focused radiation 30 (FIG. 8) by means of focusing optics 31 (FIG. 7), a guiding device 4 for stably guiding and supporting the focusing optics at the desired distance and in a desired oblique irradiation angle (FIG. 6) relative to the surface of the glass tube 2, and a glass tube take-off device 5. Laser-based irradiation device 3 comprises a laser 32, a guide head 33 for the focusing optics 31, and a hollow fiber 34 connecting the laser 32 to the focusing optics 31. The guide head 33 furthermore includes sensors 35, 36 (FIG. 7) for determining the distance of focusing optics 31 to the surface of the glass tube 2 and the position of produced filaments 6 (FIGS. 10 and 11). The guide head 33 is guided by the guiding device 4, which may form part of a robot, such that the focusing optics 31 within the guide head 33 can be guided around the glass tube at the desired distance and in the desired angular orientation with respect to the surface of the glass tube 2 and in a desired separation plane of the glass tube.

[0050] A suitable laser for an apparatus according to the invention is a neodymium-doped yttrium-aluminum-garnet laser with a wavelength of 1064 nanometers, which may also be operated in a frequency-doubled mode. In this case, a suitable pulse duration of a laser pulse is preferably shorter than 100 picoseconds, more preferably shorter than 10 picoseconds.

[0051] FIG. 6 shows the scheme for producing filaments 6 in the separation plane 20 of glass tube 2. Indicated therein is the radius vector 200 which is perpendicular to the surface of glass tube 2, and the irradiation axis 300 of focused radiation 30, which are offset in parallel to each other by an offset d. Thus, the oblique irradiation angle is resulting. Due to refraction in glass, the irradiation axis is refracted towards the axis of the tube, resulting in an angle between the local radius vector r and the local axis of irradiation. Furthermore, it is intended that the glass tube 2 and the irradiation device 3 are rotated relative to each other in increments of an angular velocity .

[0052] FIG. 7 shows an enlarged section of FIG. 6, although with sets 60 of filaments 6, which have been produced after corresponding incremental rotations of the glass tube 2 (with altered position of the guide head 33). Furthermore, the guide head 33 is illustrated schematically, including the focusing optics 31 and sensors 35, 36, wherein sensor 35 is used as a distance sensor for determining the distance of focusing optics 31 from glass tube 2 and sensor 36 is used as a scanning sensor for identifying produced filaments 6.

[0053] FIG. 8 shows an enlarged computer-generated scheme of focused radiation 30 for producing filaments 6 in a glass tube 2 that has an inner radius r. The offset d between radius vector 200 and irradiation axis 300 is approximately 1 mm for a glass tube having an inner radius of r=6 mm.

[0054] FIG. 9 shows an enlarged micrograph of the separation plane 20 as a fracture surface featuring a multitude of filaments 6 that extend obliquely to the local radius vector, at an angle .

[0055] FIGS. 10 and 11 show further enlarged micrographs of the separation plane 20 as a fracture surface featuring opened filaments 6 which extend at a spacing 61 from each other.

[0056] Such filaments 6 have been produced using a laser-based irradiation device 3 comprising a biconvex lens with a focal length of 16 mm and an aperture of 18 mm. The laser emitted radiation of a wavelength of 1064 nm, with pulse energy >200 J, burst energy of 100 J for 4 bursts, and with a burst frequency of 50 MHz. Pitch was 8 m, focal position was 1.25 mm, and offset was d=1 mm. The glass tube had an outer diameter of 6.85 mm and a wall thickness of about 1 mm.

[0057] The feeding device 1 may be a device for drawing glass from the melt, or else a redrawing device. However, it is also possible to use a discontinuously operated feeding device. Depending on whether the glass tube 2 is stationary or in longitudinal advancement when introducing the filaments 6, the guide head 33 will perform a rotational movement or a helical movement in space, but always in alignment with the surface of the glass tube 2. The rotational movement or helical movement of the guide head 33 can be considered as an orbital revolution of the irradiation device 3 with respect to the desired separation plane 20. The orbital movement is synchronized with the movement of the glass tube 2 such that the radiation 30 emitted by the irradiation device and guided by the guide head 33 always propagates in the desired separation plane 20. Here, the focused radiation 30 is not incident centrically on the glass tube 2, but at a specific offset d to the radius (FIG. 6), so that an oblique irradiation angle is resulting relative to the local tangent to the glass tube, which may range from less than 90 to 70, preferably from 89.5 to 75, more preferably from 89 to 80, most preferably between 85 and 80. The optimum oblique irradiation angle depends on the tube's diameter and on the optical properties of the material. The respective most favorable value is determined by tests or calculations.

[0058] FIG. 2 shows an embodiment of the apparatus for preparing the separation of tube glass into severed glass tube portions 21 (FIG. 5), in which the laser-based irradiation device 3 comprises a rotatable scanner head 41 with beam guidance to the focusing optics 31 disposed on the inner surface of an annular mirror 42 that defines an annular space through which the glass tube 2 to be processed extends. The rotatable scanner head 41 and the annular mirror 42 together form a guiding device 4 for focusing optics 31. The irradiation device 3 comprises one or more lasers (not shown) for simultaneously supplying one or more laser beams to the focusing optics 31. The annular mirror 42 has a faceted inner surface which is inclined towards the glass tube 2 which extends through the annular space of annular mirror 42. The facets ensure that an oblique irradiation angle is maintained.

[0059] The embodiment of the apparatus according to FIG. 2 is designed for stationary operation. The glass tube 2 is intermittently advanced and locked, whereupon the filaments 6 are produced in a desired separation plane 20 of the glass tube 2 by operation of the irradiation device 3. The filaments 6 extend obliquely, as shown in FIGS. 9 to 11.

[0060] The embodiment of FIG. 2 can also be built for continuous operation. The distance between feeding device 1 and glass tube take-off device 5 is increased to at least twice the distance shown in FIG. 2. Furthermore, the laser-based irradiation devices 3 and the guiding device 4 are configured for moving concomitantly with the glass tube 2 feeding device 1. In this way, the filaments 6 can be produced in the desired separation plane during the concomitant movement. Thereafter, the guiding device is returned to its initial position, to immediately again move forward together with the advancing glass tube.

[0061] The embodiment of the apparatus according to FIG. 3 represents a modification of the embodiment of FIG. 2. The mirror comprises mirror portions 43 arranged along a helix. Glass tube 2 can be advanced continuously while being provided with the filaments 6 in the desired separation plane. The mirror portions 43 are successively exposed to the laser beam in synchronization with the advancement rate of the glass tube such that the filaments 6 are produced in the desired separation plane.

[0062] FIG. 4 shows an embodiment of the apparatus in which the annular mirror comprises portions 44 that are designed as imaging optics. The imaging optics are suitable for tube glass with radii greater than 10 mm. If the radii are smaller than 10 mm, intermediate optics (not shown) similar to the focusing optics 31 of FIGS. 2 and 3 are used additionally, so that the injection angle of the laser irradiation can be enlarged and the filament 6 in the interior of the glass tube 2 will be more pronounced than without this measure.

[0063] Intermediate optics between the focusing optics 31 and the glass tube surface may also be used in the embodiments of FIGS. 1 to 3. It is also possible to use an immersion liquid with a high refractive index compared to air as intermediate optics, where this is feasible.

[0064] FIG. 5, in which the feeding device and the take-off device for glass tube 2 has been omitted, shows a further embodiment. The configuration corresponds to the embodiment of FIG. 2. The glass tube 2 is advanced intermittently, and the separation plane is marked with filaments 6. However, separation of the sized glass tube portion is achieved still within the apparatus. For this purpose, a separation device 8 is employed, which subjects the glass tube 2 to a mechanical pressure or to a cold shock at the separation point, so that a glass tube portion 21 is separated from the supplied glass tube 2. The separated glass tube portion 21 is removed by some means (not shown).

[0065] The fracture surface generated along separation plane 20 exhibits a certain roughness, as can be seen in the micrographs of FIGS. 9 to 11. However, the fracture surface is free of particles, if particle is understood to mean chippings greater than 150 m or 100 m, or 50 m, or even only 20 m. Striking traces that can be seen in the fracture surface are obliquely extending broken open filaments 6. The filaments 6 are laser-generated channel-like perforations or partial perforations in the tube wall of glass tube 2. The inclination angle (FIG. 6) defined between the extension of filaments 6 and the local tube radius r is in a range from 1 to 15, with tubes of larger diameter exhibiting the smaller angles and tubes of smaller diameter exhibiting the larger angles. Angle values in the range from 5 to 10 have proved to be most advantageous. Filaments 6 have a filament spacing 61 from each other ranging from 2 m to 15 m. A range of spacings between 4 m and 8 m is preferred.

[0066] The fracture surface need not be continuously covered by filaments 6, as is illustrated in FIG. 7. Filament areas 60 may alternate with unaffected areas. The filament areas 60 each comprise a set of individual filaments 6, which are themselves spaced apart, as mentioned previously. The unaffected areas between the filament areas 60 may have an extent of at least 50 m or at least 100 m, measured in the circumferential direction of the tube. The number of filament areas 60 (and therefore also that of unaffected areas) is up to twelve areas, which are distributed around the circumference of the glass tube. The filament areas 60 occupy at least 8%, preferably at least 16%, or most preferably 32% or more of the circumference of the glass tube. Thus, the separation of tube glass into glass tube portions can be achieved with little energy consumption, and yet clean fracture surfaces can be achieved.

[0067] FIG. 12 shows a glass tube portion 21 as an example of a glass precursor for producing an ampoule. The glass tube portion has portion ends 22, 23 produced by separation, and has filament areas 60 at predetermined distances from these portion ends 22, 23. By way of example, the filament regions 60 occupy two opposing 120 segments with ends that are spaced by 60 from each other. To produce an ampoule, a glass wall region 24 between portion end 22 and filament areas 60 is expanded in a warm state, and the portion ends 22, 23 are prepared for being sealed, whereafter the ampoule is filled and sealed.

[0068] It will be apparent to those skilled in the art that the embodiments as described above are meant by way of example only and that the invention is not limited thereto, but rather can be varied in many ways without thereby departing from the scope of the claims. Furthermore, it will be appreciated that the features, whether disclosed in the specification, the claims, the figures, or otherwise, define essential components of the invention also individually, even if described together with other features.

LIST OF REFERENCE NUMERALS

[0069] 1 Feeding device [0070] 2 Glass tube [0071] 20 Separation plane [0072] 21 Glass tube portion [0073] 22, 23 End of portion [0074] 24 Glass wall region [0075] 200 Radius vector [0076] 3 Irradiation device [0077] 30 Focused radiation [0078] 31 Focusing optics [0079] 32 Laser [0080] 33 Guide head [0081] 34 Hollow fiber [0082] 35 Distance sensor [0083] 36 Scanning sensor [0084] 300 Irradiation axis [0085] 4 Guiding device [0086] 41 Scanner head [0087] 42 Annular mirror [0088] 43 Mirror portion [0089] 44 Portion of annular mirror [0090] 5 Take-off device [0091] 6 Filament [0092] 60 Filament area [0093] 61 Filament spacing [0094] 8 Separation device