GLASS TUBE ELEMENT WITH IMPROVED QUALITY

Abstract

A glass tube element having a hollow cylindrical section with a shell having an outer diameter is provided. A first ratio is a difference value to a mean value. The difference value is a difference of a minimal and maximal value of the outer diameter. The mean value is a mean of the minimal and maximal values. A sub-section having a start, an end, and a distance of 1 meter measured along a straight line from the start to the end and intersecting with a center axis of the sub-section at the start and the end. The sub-section having, for every point of the center axis, a shortest distance to the straight line. A second ratio of a specific distance to 1 meter, the specific distance being defined as a largest of all shortest distances. A product of the first and second ratio is smaller than 4×10.sup.−6.

Claims

1. A glass tube element, comprising: a hollow cylindrical section having a shell, a sub-section, and a main extension along a center axis, wherein the shell has an outer diameter in a specific cross-sectional plane that is perpendicular to the main extension, wherein the outer diameter in the specific cross-sectional plane has a minimal outer diameter and a maximal outer diameter, wherein the sub-section has a start, an end, and a distance measured along a straight line from the start to the end and intersecting with the center axis at the start and the end, the sub-section having, for every point of the center axis, a shortest distance to the straight line; a first ratio that is smaller than 0.005, the first ratio being of an absolute value to a mean value, the absolute value being a difference of the minimal and the maximal outer diameters, and the mean value being of the minimal and maximal outer diameters; and a second ratio that is smaller than 0.00075, the second ratio being of a specific distance to 1 meter, the specific distance being defined as a largest of all shortest distances.

2. The glass tube element of claim 1, wherein the first ratio is smaller than 0.004.

3. The glass tube element of claim 1, wherein the first ratio is smaller than 0.003.

4. The glass tube element of claim 1, wherein the first ratio is smaller than 0.002.

5. The glass tube element of claim 1, wherein the first ratio is smaller than 0.001.

6. The glass tube element of claim 1, wherein the second ratio is smaller than 0.0006.

7. The glass tube element of claim 1, wherein the second ratio is smaller than 0.0004.

8. The glass tube element of claim 1, wherein the second ratio is smaller than 0.0002.

9. The glass tube element of claim 1, further comprising a product of the first and second ratio that is smaller than 4×10.sup.−6.

10. The glass tube element of claim 1, further comprising a product of the first and second ratio that is smaller than 3×10.sup.−6.

11. The glass tube element of claim 1, further comprising a product of the first and second ratio that is smaller than 2×10.sup.−6.

12. The glass tube element of claim 1, further comprising a product of the first and second ratio that is smaller than 1×10.sup.−6.

13. The glass tube element of claim 1, further comprising a product of the first and second ratio that is smaller than 0.5×10.sup.−6.

14. The glass tube element of claim 1, wherein the glass tube element has a length of between 0.5 and 5 m.

15. The glass tube element of claim 1, wherein the maximal value of the outer diameter is between 1 and 100 mm.

16. The glass tube element of claim 1, wherein the shell has an average thickness of between 0.1 and 5 mm.

17. The glass tube element of claim 1, comprising a glass selected from a group consisting of silicate glass, soda line, alumosilicate glass, borosilicate glass, and any combinations thereof.

18. The glass tube element of claim 1, comprising a glass with a transition temperature that is higher than 300 degrees C. and lower than 900 degrees C.

19. The glass tube element of claim 1, comprising a glass with an average linear coefficient of thermal expansion measured in the range of 20 degrees C. to 300 degrees C. (CTE) between 3.0 and 10.0*10.sup.−6 K.sup.−1.

20. The glass tube element of claim 1, wherein the glass tube element is configured as a pharmaceutical container selected from a group consisting of a vial, a cartridge, an ampoule, and a syringe.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0126] Various aspects of this invention will become apparent to those skilled in the art from the following detailed description of preferred embodiments, when read in light of the accompanying schematic drawings, wherein:

[0127] FIG. 1a shows a schematic perspective representation of a glass tube element according to the invention.

[0128] FIG. 1b shows a schematic representation of a setup for obtaining parameters for the second ratio.

[0129] FIG. 2 shows a glass tube element according to the invention.

[0130] FIG. 3 shows a schematic illustration of a first exemplary production line.

[0131] FIG. 4 shows a schematic cross-sectional view of a contacting device.

[0132] FIG. 5 shows a schematic illustration of a second exemplary production line.

[0133] FIG. 6 shows a schematic illustration of a third exemplary production line.

[0134] FIG. 7 shows a schematic illustration of a fourth exemplary production line.

[0135] FIG. 8 shows a schematic illustration of a fifth exemplary production line.

DETAILED DESCRIPTION

[0136] FIG. 1a shows a schematic perspective representation of a glass tube element 1 according to the invention.

First Ratio

[0137] The glass tube element 1 has a complete hollow cylindrical form (not only a section thereof) and a shell 3 which encloses a lumen 5. In the particular example of FIG. 1a all cross-sectional planes of the glass tube element 1 obtained by means of a plane perpendicular to the direction of the main extension of the glass tube element 1 are identical. Therefore, the plane comprising the end of the glass tube element which is pointing towards the viewer in FIG. 1a can be regarded exemplary as a specific cross-sectional plane of the glass tube element 1 for further explanation.

[0138] It is apparent that the outer diameter of the shell 3 varies between a minimal diameter representing a circle 7 and a maximal diameter representing a circle 9 in the specific cross-sectional plane. Both circles 7, 9 are concentric.

[0139] For obtaining the first ratio, the absolute value of the difference of the minimal and maximal outer diameter of the shell 3 is needed. The minimal outer diameter of the shell 3 is the diameter of circle 7. The maximal outer diameter of the shell 3 is the diameter of circle 9. The difference is indicated in FIG. 1a as d. Further, the mean value of the minimal and maximal outer diameter of the shell 3 is needed.

[0140] It is appreciated that in case of a glass tube element with varying thicknesses and/or geometries of the shell, for each cross-sectional plane a different pair of circles 7, 9 might be obtained. However, according to the definition, for obtaining the first ratio the pair of circles from all cross-sectional planes (being perpendicular to the direction of the extension of the glass tube element 1) is to be used which yield the largest absolute value d.

Second Ratio

[0141] The second ratio is based on the specific distance.

[0142] FIG. 1b shows a schematic representation of a setup for obtaining parameters for the second ratio. In preferred cases the glass tube element is subject to symmetric bending, i.e., bending which is symmetric between the two ends of the glass tube element. However, in general the bending might not be symmetric.

[0143] A class tube element 11 is supported by two supports 13. The distance e between the supports 13 is 1000 mm. Indeed, the distance e is measured along a straight line 15 from the start to the end of some sub-section of the section of the glass tube element 11. Of course if the sub-section of the section of the class tube element extending between the two supports is bended, the true length of that sub-section between the two supports might be longer than the distance of 1 meter between the two supports.

[0144] For every point of the center axis of the sub-section of the section of the glass tube element a shortest distance to the straight line 15 is or can be identified. In the illustration of FIG. 1b the glass tube element and its center axis are depicted by the same single line.

[0145] Then the class tube element 11 is rotated on the supports 13 (indicated by the arrow in FIG. 1b). FIG. 1b shows the glass tube element 11 in two positions having a difference in the rotation angle of 180 degrees. The sag t of the glass tube element 11 corresponds to the specific distance. This is because the specific distance is the largest of all shortest distances. For the situation shown in FIG. 1b the largest of all shortest distances can be found in the middle between the two supports 13 due to symmetric bending of the glass tube element 11 between the two supports 13.

[0146] Here, the sag t corresponds to the specific distance according to the invention.

[0147] It is acknowledged that for other types of glass tube elements, other setups might be employed.

[0148] The second ratio can then be obtained with said specific distance of the class tube element 11.

Further Glass Properties

[0149] The coefficient of linear thermal expansion (CTE) is a measure of characterizing the expansion behavior of a glass when it experiences certain temperature variation. CTE may be the average linear thermal expansion coefficient in a temperature range of from 20° C. to 300° C. as defined in DIN ISO 7991:1987. The lower the CTE, the less expansion with temperature variation. Therefore, in the temperature range of from 20° C. to 300° C. the glass of the wall of the glass tube element of the present invention preferably has a CTE of less than 12 ppm/K, more preferably less than 10.0 ppm/K, more preferably less than 9.0 ppm/K, more preferably less than 8.0 ppm/K, more preferably less than 7 ppm/K, more preferably less than 6.5 ppm/K. However, the CTE should also not be very low. Preferably, in the temperature range of from 20° C. to 300° C. the CTE of the glasses of the present invention is more than 3 ppm/K, more preferably more than 4 ppm/K, more preferably more than 5 ppm/K, more preferably more than 6 ppm/K. In order for the glasses to be well suitable for chemical toughening, the glasses may contain relatively high amounts of alkali metal ions, preferably sodium ions. However, thereby the average linear thermal expansion coefficient CTE in the temperature range between 20° C. and 300° C. is increased. Preferably, the glass of the wall of the glass tube element of the invention has a CTE higher than 7*10.sup.−6/° C., more preferably higher than 8*10.sup.−6/° C., more preferably higher than 9*10.sup.−6/° C. However, a high CTE also complicates production of the glasses by direct hot-forming. Therefore, the glasses preferably have a CTE lower than 13*10.sup.−6/° C.

[0150] The transition temperature of the glass used for the wall of the glass tube element may be higher than 300° C., higher than 500° C., higher than 520° C., higher than 530° C., higher than 550° C., or even higher than 600° C. The transition temperature of the wall of the glass tube element may be lower than 900° C., lower than 800° C., lower than 700° C., lower than 650° C., or lower than 630° C. Generally, a low transition temperature usually includes lower energy costs for melting the glass and for processing. Also, the glass will usually have a lower fictive temperature if the transition temperature is low. Hence, the glass will be less prone to irreversible thermal shrinkage during optional chemical toughening, if the transition temperature is higher.

[0151] The glass tube element should be manufactured with a high purity and it should feature a good resistance, especially against alkaline solutions. The resistance against alkaline solutions is important for the use of glass tube elements.

[0152] The average surface roughness (R.sub.a) is a measure of the texture of a surface. It is quantified by the vertical deviations of a real surface from its ideal form. Commonly amplitude parameters characterize the surface based on the vertical deviations of the roughness profile from the mean line. R.sub.a is arithmetic average of the absolute values of these vertical deviations. The roughness can be measured with atomic force microscopy. The inner surface and/or outer surface of the glass tube element preferably has an average surface roughness Ra of less than 30 nm, of less than 10 nm, of less than 5 nm, of less than 2 nm, of less than 1 nm. In some embodiments, the surface roughness Ra is less than 0.5 nm. A smaller inner and/or outer surface roughness reduces the amount residual fluid. Residual fluid within the glass tube element can give rise to growth of microorganisms which could harm the health of animals or humans. Furthermore, a smaller outer surface roughness gives a more pleasant feeling when holding the glass tube element in the hand. The mentioned roughness values can be obtained by fire-polishing the glass.

Glass Compositions

[0153] The glass used for the wall of the glass tube element is not limited to a specific glass composition. The glass may be selected from the group consisting of soda-lime glass, borosilicate glass and aluminosilicate glass. Optionally, a borosilicate glass is used.

[0154] The glass of the glass tube element preferably comprises the following components in the indicated amounts (in wt. %):

TABLE-US-00001 Component Content (wt. %) SiO.sub.2 40 to 85 Al.sub.2O.sub.3 0 to 25 Na.sub.2O 0 to 18 K.sub.2O 0 to 15 MgO 0 to 10 B.sub.2O.sub.3 0 to 22 Li.sub.2O 0 to 10 ZnO 0 to 5 CaO 0 to 16 BaO 0 to 12 ZrO.sub.2 0 to 5 CeO.sub.2 0 to 0.5 SnO.sub.2 0 to 3 P.sub.2O.sub.5 0 to 15 Fe.sub.2O.sub.3 0 to 1.5 TiO.sub.2 0 to 10 SrO 0 to 1 F 0 to 1 Cl 0 to 1

[0155] SiO.sub.2 is a relevant network former that can be used in the glass used for this of the invention. Therefore, the glasses may comprise SiO.sub.2 in an amount of at least 60 wt. %. More preferably, the glass comprises SiO.sub.2 in an amount of at least 62 wt. %, at least 65 wt. %, at least 68 wt. %, more than 70 wt. %, or even more than 75 wt. %. However, the content of SiO.sub.2 in the glass should also not be extremely high because otherwise the meltability may be compromised. The amount of SiO.sub.2 in the glass may be limited to at most 85 wt. %, or at most 82 wt. %. In embodiments, the content of SiO.sub.2 in the glass is from 60 to 85 wt. %, or from >65 to 75 wt. %.

[0156] B.sub.2O.sub.3 may be used in order to enhance the network by increasing the bridge-oxide in the glass via the form of [BO.sub.4] tetrahedra. It also helps to improve the damage resistance of the glass. However, B.sub.2O.sub.3 should not be used in high amounts in the glass since it can decrease the ion-exchange performance. Furthermore, addition of B.sub.2O.sub.3 can significantly reduce the Young's modulus. The glass may comprise B.sub.2O.sub.3 in an amount of from 0 to 20 wt. %, preferably from 0 to 15 wt. %, preferably from 0.1 to 13 wt. %. In embodiments, the glass preferably comprises at least 5 wt. %, more preferably at least 7 wt. %, or at least 10 wt. % of B.sub.2O.sub.3.

[0157] P.sub.2O.sub.5 may be used in the glass of the invention in order to help lowering the melting viscosity by forming [PO.sub.4] tetrahedra, which can significantly lower the melting point without sacrificing anti-crystallization features. Limited amounts of P.sub.2O.sub.5 do not increase geometry variation very much, but can significantly improve the glass melting, forming performance, and ion-exchanging (chemical toughening) performance. However, if high amounts of P.sub.2O.sub.5 are used, geometry expansion upon chemical toughening may be increased significantly. Therefore, the glasses may comprise P.sub.2O.sub.5 in an amount of from 0 to 4 wt. %, or from 0 to 2 wt. %. In some embodiments, the glass is free of P.sub.2O.sub.5.

[0158] It is believed that Al.sub.2O.sub.3 can easily form tetrahedra coordination when the alkaline oxide ratio content is equal or higher than that of Al.sub.2O.sub.3. [AlO.sub.4] tetrahedra coordination can help building up more compact network together with [SiO.sub.4] tetrahedra, which can result in a low geometry variation of the glass. [AlO.sub.4] tetrahedra can also dramatically enhance the ion-exchange process during chemical toughening. Therefore, Al.sub.2O.sub.3 is preferably contained in the glasses in an amount of at least 0 wt. %, more preferably of more than 1 wt. %, more preferably of more than 4 wt. %. However, the amount of Al.sub.2O.sub.3 should also not be very high because otherwise the viscosity may be very high so that the meltability may be impaired. Therefore, the content of Al.sub.2O.sub.3 in the glasses is preferably at most 20 wt. %, at most 12 wt. %, or at most 10 wt. %. In preferred embodiments, the content of Al.sub.2O.sub.3 in the glasses is from 0 to 20 wt. %, from 1 to 12 wt. %, from 4 to 10 wt. %.

[0159] TiO.sub.2 can also form [TiO.sub.4] and can thus help building up the network of the glass, and may also be beneficial for improving the acid resistance of the glass. However, the amount of TiO.sub.2 in the glass should not be very high. TiO.sub.2 present in high concentrations may function as a nucleating agent and may thus result in crystallization during manufacturing. Preferably, the content of TiO.sub.2 in the glasses is from 0 to 10 wt. %, or up to 7 wt. %. In some embodiments, the glass comprises at least 0.5 wt. %, at least 2 wt. %, or at least 3 wt. % of TiO.sub.2. In an embodiment, the glass is free of TiO.sub.2.

[0160] ZrO.sub.2 has the functions of lowering the CTE and improving the alkaline resistance of a glass. It may increase the melting viscosity, which can be suppressed by using P.sub.2O.sub.5. Like alkaline metals, Zr.sup.4+ is also a network modifier. Furthermore, ZrO.sub.2 is a significant contributor for increased Young's modulus. Preferably, the content of ZrO.sub.2 in the glasses is from 0 to 5 wt. %, up to 2 wt. %. The glass may be free of ZrO.sub.2. In some embodiments, the glass comprises at least 0.1 wt. %, or at least 0.2 wt. % ZrO.sub.2.

[0161] Alkaline oxides R.sub.2O (Li.sub.2O+Na.sub.2O+K.sub.2O+Cs.sub.2O) may be used as network modifiers to supply sufficient oxygen anions to form the glass network. Preferably, the content of R.sub.2O in the glasses is more than 4 wt. %, or more than 12 wt. %. However, the content of R.sub.2O in the glass should not be very high because otherwise chemical stability and chemical toughenability may be impaired. Preferably, the glasses comprise R.sub.2O in an amount of at most 30 wt. %, at most 25 wt. %, or at most 20 wt. %. Other embodiments are free of alkaline oxides, or at least free of Na.sub.2O, K.sub.2O, Cs.sub.2O and/or Li.sub.2O

[0162] Li.sub.2O can help improving the Young's modulus and lowering CTE of the glass. Li.sub.2O also influences the ion-exchange greatly. It was surprisingly found that Li-containing glass has a smaller geometry variation. Therefore, the content of Li.sub.2O in the glasses may be set to at least 0 wt. %, or more than 5 wt. %, or even more than 10 wt. %. However, the content of Li.sub.2O should not be very high because otherwise chemical stability and chemical toughenability may be impaired. Preferably, the content of Li.sub.2O in the glasses is at most 24 wt. %, less than 15 wt. %, or even 0 wt. %.

[0163] Na.sub.2O may be used as a network modifier. However, the content of Na.sub.2O should not be very high because otherwise chemical stability and chemical toughenability may be impaired. Preferably, the content of Na.sub.2O in the glasses is from 0 to 15 wt. %, preferably from 2 to 15 wt. %. In preferred embodiments, the content of Na.sub.2O in the glasses is at least 5 wt. %, at least 8 wt. %, or at least 10 wt. %.

[0164] K.sub.2O may be used as a network modifier. However, the content of K.sub.2O should not be very high because otherwise chemical stability and chemical toughenability may be impaired. Preferably, the content of K.sub.2O in the glasses is from 0 to 15 wt. %, or from >0.5 to 7 wt. %. The glass may be free of K.sub.2O.

[0165] Preferably, the glasses comprise more Na.sub.2O than K.sub.2O. Thus, preferably the molar ratio Na.sub.2O/(Na.sub.2O+K.sub.2O) is from >0.5 to 1.0, from >0.6 to 1.0, from >0.7 to 1.0, or from >0.8 to 1.0.

[0166] Preferably, the content of the sum of Li.sub.2O and Na.sub.2O in the glasses is more than 10 mol-%, or more than 15 mol-%. However, the content of the sum of Li.sub.2O and Na.sub.2O in the glasses should not be very high. Preferably, the content of the sum of Li.sub.2O and Na.sub.2O in the glasses is at most 25 mol-%, or at most 20 mol-%.

[0167] The glasses may also comprise alkaline earth metal oxides as well as ZnO which are collectively termed “RO” in the present specification. Alkaline earth metals and Zn may serve as network modifiers. Preferably, the glasses comprise RO in an amount of from 0 to 20 wt. %, preferably from 0 to 15 wt. %. In some embodiments, the glass preferably comprises at least 0.5 wt. %, more preferably at least 1 wt. %, more preferably at least 5 wt. % of RO. Preferred alkaline earth metal oxides are selected from the group consisting of MgO, CaO, SrO und BaO. More preferably, alkaline earth metals are selected from the group consisting of MgO und CaO. More preferably, the alkaline earth metal is MgO. Preferably, the glass comprises MgO in an amount of from 0 to 10 wt. %. In some embodiments, the glass comprises at least 0.5 wt. %, at least 1 wt. %, or at least 2 wt. % of MgO. Preferably, the glass comprises CaO in an amount of from 0 to 16 wt. %, preferably from 0 to 13 wt. %, preferably from 0 to 10 wt. %. In some embodiments, the glass comprises at least 0.5 wt. %, at least 1 wt. %, at least 5 wt. %, at least 10 wt. %, or at least 12 wt. % of CaO. Preferably, the glass comprises BaO in an amount of from 0 to 12 wt. %, preferably from 0 to 10 wt. %. In some embodiments, the glass comprises at least 0.5 wt. %, at least 2 wt. %, or at least 7 wt. % of BaO. The glass may be free of BaO, MgO and/or CaO.

[0168] Preferably, the glass comprises ZnO in an amount of from 0 to 5 wt. %. In some embodiments, the glass comprises at least 0.5 wt. %, at least 1 wt. %, or at least 2 wt. % of ZnO. In other embodiments, the glass is free of ZnO. Preferably, the content of the sum of MgO and ZnO in the glasses is from 0 to 10 wt. %. In some embodiments, the content of the sum of MgO and ZnO in the glasses at least 0.5 wt. %, more preferably at least 1 wt. %, more preferably at least 2 wt. %.

[0169] At the end, when forming a glass by mixing different types of the oxides, the integrated effect should be considered to achieve a glass with comparatively low expansion, which is supported by high densification of the glass network. It means, in addition to [SiO.sub.4] tetrahedral [BO.sub.4] tetrahedra, [AlO.sub.4] tetrahedra, or [PO.sub.4] tetrahedra are expected to help connect the [SiO.sub.4] more effectively rather than other type of polyhedrons. In other words, [BO.sub.3] triangle and [AlO.sub.6] octahedron, for instance, are not preferred. It means, sufficient oxygen anions are preferable to be offered by adding proper amounts of metal oxides, such as R.sub.2O and RO.

[0170] Preferably, the content of SnO.sub.2 in the glasses is from 0 to 3 wt. %. More preferably, the glasses are free of SnO.sub.2. Preferably, the content of Sb.sub.2O.sub.3 in the glasses is from 0 to 3 wt. %. More preferably, the glasses are free of Sb.sub.2O.sub.3. Preferably, the content of CeO.sub.2 in the glasses is from 0 to 3 wt. %. High contents of CeO.sub.2 are disadvantages because CeO.sub.2 has a coloring effect. Therefore, more preferably, the glasses are free of CeO.sub.2. Preferably, the content of Fe.sub.2O.sub.3 in the glasses is from 0 to 3 wt. %. More preferably, the glasses are free of Fe.sub.2O.sub.3.

[0171] The glass described herein is described as having a composition of different constituents. This means that the glass contains these constituents without excluding further constituents that are not mentioned. However, in preferred embodiments, the glass consists of the components mentioned in the present specification to an extent of at least 95%, more preferably at least 97%, most preferably at least 99%. In most preferred embodiments, the glass essentially consists of the components mentioned in the present specification.

[0172] Optionally, coloring oxides can be added, such as Nd.sub.2O.sub.3, Fe.sub.2O.sub.3, CoO, NiO, V.sub.2O.sub.5, MnO.sub.2, CuO, CeO.sub.2, Cr.sub.2O.sub.3.

[0173] 0-2 wt. % of As.sub.2O.sub.3, Sb.sub.2O.sub.3, SnO.sub.2, SO.sub.3, Cl and/or F could be also added as refining agents. 0-5 wt. % of rare earth oxides could also be added to add optical or other functions to the glass wall.

[0174] The terms “X-free” and “free of component X”, or “0% of X”, respectively, as used herein, refer to a glass, which essentially does not comprise said component X, i.e., such component may be present in the glass at most as an impurity or contamination, however, is not added to the glass composition as an individual component. This means that the component X is not added in essential amounts. Non-essential amounts according to the present invention are amounts of less than 100 ppm, preferably less than 50 ppm and more preferably less than 10 ppm. Preferably, the glasses described herein do essentially not contain any components that are not mentioned in this description.

[0175] In embodiments, the glass used for the glass tube element has the following composition in percent by weight:

TABLE-US-00002 Component Content (wt. %) SiO.sub.2 40 to 85 Al.sub.2O.sub.3 0 to 25 Na.sub.2O 2 to 18 K.sub.2O 0 to 15 MgO 0 to 10 B.sub.2O.sub.3 0 to 15 Li.sub.2O 0 to 10 ZnO 0 to 5 CaO 0 to 10 BaO 0 to 5 ZrO.sub.2 0 to 5 CeO.sub.2 0 to 0.5 SnO.sub.2 0 to 3 P.sub.2O.sub.5 0 to 15 Fe.sub.2O.sub.3 0 to 1.5 TiO.sub.2 0 to 10 SrO 0 to 1 F 0 to 1 Cl 0 to 1

[0176] In embodiments, the glass used for the glass tube element has the following composition in percent by weight:

TABLE-US-00003 Component Content (wt. %) SiO.sub.2 55 to 65 Al.sub.2O.sub.3 10 to 20 Na.sub.2O 0 to 3 K.sub.2O 0 to 3 MgO 0 to 5 B.sub.2O.sub.3 0 to 6 Li.sub.2O 0 to 3 ZnO 0 to 3 CaO 7 to 15 BaO 5 to 10 ZrO.sub.2 0 to 3 CeO.sub.2 0 to 0.5 SnO.sub.2 0 to 3 P.sub.2O.sub.5 0 to 3 Fe.sub.2O.sub.3 0 to 1.5 TiO.sub.2 0 to 3 SrO 0 to 1 F 0 to 1 Cl 0 to 1

[0177] In embodiments, the glass used for the glass tube element has the following composition in percent by weight:

TABLE-US-00004 Component Content (wt. %) SiO.sub.2 65 to 85 Al.sub.2O.sub.3 0 to 7 Na.sub.2O 0.5 to 10 K.sub.2O 0 to 10 MgO 0 to 3 B.sub.2O.sub.3 8 to 20 Li.sub.2O 0 to 3 ZnO 0 to 3 CaO 0 to 3 BaO 0 to 3 ZrO.sub.2 0 to 3 CeO.sub.2 0 to 0.5 SnO.sub.2 0 to 3 P.sub.2O.sub.5 0 to 3 Fe.sub.2O.sub.3 0 to 1.5 TiO.sub.2 0 to 3 SrO 0 to 1 F 0 to 1 Cl 0 to 1

[0178] In embodiments, the glass used for the glass tube element has the following composition in percent by weight:

TABLE-US-00005 Component Content (wt. %) SiO.sub.2 60 to 80 Al.sub.2O.sub.3 0 to 5 Na.sub.2O 10 to 18 K.sub.2O 0 to 5 MgO 0 to 5 B.sub.2O.sub.3 0 to 5 Li.sub.2O 0 to 3 ZnO 0 to 3 CaO 2 to 10 BaO 0 to 5 ZrO.sub.2 0 to 3 CeO.sub.2 0 to 0.5 SnO.sub.2 0 to 3 P.sub.2O.sub.5 0 to 3 Fe.sub.2O.sub.3 0 to 1.5 TiO.sub.2 0 to 3 SrO 0 to 1 F 0 to 1 Cl 0 to 1

Optional Additional Treating of the Glass Tube Element

[0179] For optional chemical toughening, the glass may be immersed in a salt bath. The salt bath may contain sodium and/or potassium salts. The salt for the salt bath may comprise Na, K or Cs nitrate, sulfate or chloride salts or a mixture of one or more thereof. Preferred salts are NaNO.sub.3, KNO.sub.3, NaCl, KCl, K.sub.2SO.sub.4, Na.sub.2SO.sub.4, Na.sub.2CO.sub.3, K.sub.2CO.sub.3, or combinations thereof. Additives like NaOH, KOH and other sodium or potassium salts may also be used for better controlling the speed of ion-exchange, compressive stress and DoL during chemical toughening. In an embodiment, the salt bath comprises KNO.sub.3, NaNO.sub.3, CsNO.sub.3 or mixtures thereof.

[0180] The temperature during chemical toughening may range from 320° C. to 700° C., from 350° C. to 500° C., or from 380° C. to 450° C. If the toughening temperature is very low, the toughening rate will be low. Therefore, chemical toughening is preferably done at a temperature of more than 320° C., more preferably more than 350° C., more preferably more than 380° C., more preferably at a temperature of at least 400° C. However, the toughening temperature should not be very high because very high temperatures may result in strong compressive stress relaxation and low compressive stress. Preferably, chemical toughening is done at a temperature of less than 500° C., more preferably less than 450° C.

[0181] The time for chemical toughening may range from 5 min to 48 h, from 10 min to 20 h, from 30 min to 16 h, or from 60 min to 10 h. In preferred embodiments, the duration of chemical toughening is of from 0.5 to 16 h. Chemical toughening may either done in a single step or in multiple steps, in particular in two steps. If the duration of toughening is very low, the resulting DoL may be very low. If the duration of toughening is very high, the CS may be relaxed very strongly. The duration of each toughening step in a multistep toughening procedure is preferably between 0.05 and 15 hours, more preferably between 0.2 and 10 hours, more preferably between 0.5 and 6 hours, more preferably between 1 and 4 hours. The total duration of chemical toughening, in particular the sum of the durations of the two or more separate toughening steps, is preferably between 0.01 and 20 hours, more preferably between 0.2 and 20 hours, more preferably between 0.5 and 15 hours, more preferably between 1 and 10 hours, more preferably between 1.5 and 8.5 hours. Glass tube element may be chemically toughened such that it has a DoL of at least 10 μm, or at least 20 μm. In some embodiments, the DoL may be up to 80 μm, up to 60 μm or up to 50 μm.

[0182] In some embodiments, the glass is chemically toughened with a mixture of KNO.sub.3 and NaNO.sub.3. In embodiments, the mixture comprises less than 50 mol % NaNO.sub.3, less than 30 mol % NaNO.sub.3, less than 20 mol % NaNO.sub.3, less than 10 mol % NaNO.sub.3, or less than 5 mol % NaNO.sub.3. In some embodiments, the glass is chemically toughened with a mixture of KNO.sub.3 and CsNO.sub.3. In embodiments, the mixture comprises less than 50 mol % CsNO.sub.3, less than 30 mol % CsNO.sub.3, less than 20 mol % CsNO.sub.3, less than 10 mol % CsNO.sub.3, or less than 5 mol % CsNO.sub.3. The balance may be KNO.sub.3.

[0183] Chemical toughening with both KNO.sub.3 and NaNO.sub.3 may be done by using a mixture of KNO.sub.3 and NaNO.sub.3 or by performing separate toughening steps with essentially pure NaNO.sub.3 and essentially pure KNO.sub.3. Also in embodiments in which the glass is chemically toughened with mixtures of KNO.sub.3 and NaNO.sub.3, preferably two distinct consecutive toughening steps are performed. Preferably, the proportion of KNO.sub.3 in the mixture used for the second toughening step is higher than the proportion of KNO.sub.3 in the mixture used for the first toughening step. The chemical toughening can include multi steps in salt baths with alkaline metal ions of various concentrations to reach better toughening performance.

[0184] The toughening can be done by immersing the glass into a molten salt bath of the salts described above, or by covering the glass with a paste containing the ions described above, e.g., potassium ions and/or other alkaline metal ions, and heating to a high temperature for a certain time. The alkaline metal ions with larger ion radius in the salt bath or the paste exchange with alkaline metal ions with smaller radius in the glass article, and surface compressive stress is formed due to ion exchange.

[0185] A chemically toughened glass tube element of the invention may be obtained by chemically toughening at least the wall of the glass tube element of the present invention. The toughening process can be done by partially or completely immersing the glass tube element, the glass tube, the glass wall, or any intermediate glass article into an above-described salt bath, or subjecting it to a salt paste. The monovalent ions in the salt bath have radii larger than alkali ions inside the glass. A compressive stress to the glass is built up after ion-exchange due to larger ions squeezing in the glass network. After the ion-exchange, the strength and flexibility of the glass is surprisingly and significantly improved. In addition, the compressive stress induced by chemical toughening may increase scratch resistance of the glass tube element. Improved scratch resistance is particularly relevant for glass tube elements because scratches affect both mechanical and chemical resistance of a glass surface as well as optical appearance.

[0186] After chemical toughening, the glass tubes are taken out of the salt bath, then cleaned with water and dried. Compressive stress layers are formed on the outer surface and/or inner surface of strengthened glass tubes. Correspondingly, a tensile stress is formed in the core part of the glass tubing wall.

[0187] It is acknowledged that preferably any existing stress layers or stress patterns may be superimposed with the stress layers or stress patterns introduced by subsequent chemical toughening. Especially the depth of the stress layers/patterns introduced by chemical toughening may be for example 50 μm while other stress layers/patterns may extend across the entire depth of the glass material. This might lead to the situation that any former stress layers/patterns or parts thereof is or are at least in some volume/surface domains biased by some value dependent on the chemical toughening process.

Toughening

[0188] One or more types of toughening might be applied to the glass tube element during the manufacturing process. For example a glass tube element might be chemically toughened. This type of toughening is explained in detail elsewhere in this application.

[0189] The threshold diffusivity D of the wall of the glass tube element preferably is at least 1.5 μm.sup.2/hour, more preferably at least 4 μm.sup.2/hour. The chemical toughening performance of glass can be described by the threshold diffusivity D. The threshold diffusivity D can be calculated from the measured depth of layer (DoL) and the ion exchange time (IET) according to the relationship: DoL=˜1.4 sqrt (4*D*IET). The threshold diffusivity may for example be measured when chemically toughening the glass at 410° C. in KNOB for 8 hours. The glass used for the glass tube element may have excellent chemical toughening performance which allows for a very economic production. Thus, the glass may have a threshold diffusivity D of at least 1.5 μm.sup.2/hour. Preferably, the glass of the present invention has a threshold diffusivity D of at least 4 μm.sup.2/hour, at least 6 μm.sup.2/hour, at least 8 μm.sup.2/hour, at least 10 μm.sup.2/hour, at least 12 μm.sup.2/hour, at least 14 μm.sup.2/hour, at least 16 μm.sup.2/hour, at least 18 μm.sup.2/hour, at least 20 μm.sup.2/hour, at least 25 μm.sup.2/hour, at least 30 μm.sup.2/hour, at least 35 μm.sup.2/hour, or even at least 40 μm.sup.2/hour. In an embodiment, the threshold diffusivity is up to 60 μm.sup.2/hour or up to 50 μm.sup.2/hour.

[0190] In some embodiments chemical toughening is employed.

Cutting Mechanism

[0191] In preferred embodiments at least one out of three cutting mechanisms might be applied for manufacturing the glass tube elements, i.e., to prepare the desired length of each glass tube element from a longer glass element such as a glass tube line: 1. scratching, which means that at desired positions the longer glass element is scratched and broken in order to obtain the individual glass tube elements. This technique might be also referred to as “score broken”. 2. Sawing, which means that at the desired positions the longer glass element is sawed so that individual glass tube elements are obtained. 3. Laser cutting, which means that the individual glass tube elements are obtained in that a laser cuts the individual pieces from the longer glass element.

[0192] In preferred embodiments a laser cutting technique is employed.

Polishing

[0193] In preferred embodiments all or at least one or more parts of the glass tube elements can be made subject to fire polishing. This means that the material is exposed to a flame or heat, for example during drawing of the glass tube or afterwards. This might result in a smoothening of the surface. Preferably at least the end sections of the glass tube elements are fire polished. More preferably the entire glass tube element is fire polished, at least its outer surface. Reference is also made to the discussion made with respect to surface roughness above.

[0194] FIG. 2 shows a glass tube element 101 according to the invention.

[0195] It has a hollow cylindrical form (not only a section thereof, but entirely) and a shell 103 which encloses a lumen 105. The length (this is, from top to bottom) of the glass tube element 101 is 1.5 m. The maximal outer diameter of the glass tube element 101 is between 6 and 25 mm. Indeed, the nominal outer diameter is 24 mm. The shell 103 has an average thickness T of 1 mm.

[0196] There is a specific cross-sectional plane perpendicular to the direction R of the main extension of the glass tube element 101 in which plane the difference of the minimal and maximal outer diameter of the shell 103 has the largest absolute value. (There can be, of course, more than one plane which is perpendicular and in which the difference has the same maximal value. In this case every one of the planes can be chosen as specific cross-sectional plane.)

[0197] A first ratio of the difference value of the minimal and the maximal value of the outer diameter of the shell in the specific cross-sectional plane of the glass tube element on the one hand and the mean value of the minimal and maximal value of the outer diameter of the shell in the specific cross-sectional plane of the glass tube element on the other hand is defined. For the glass tube element 101 this first ratio is smaller than 4×10.sup.−3.

[0198] Furthermore, a second ratio of a specific distance and 1 meter is defined.

[0199] Some sub-section of the section of the glass tube element 101 having at least one start and at least one end is or can be selected, wherein a distance of 1 meter is or can be measured along a straight line (not shown in FIG. 2) from the start to the end.

[0200] For every point of the center axis (not shown in FIG. 2) of the sub-section of the section of the glass tube element 101 a shortest distance to the straight line is or can be identified.

[0201] The specific distance being defined as the largest of all shortest distances. For the glass tube element 101 this second ratio is smaller than 0.7×10.sup.−3.

[0202] The product of the first and second ratio is smaller than 4.0×10.sup.−6 for the glass tube element 101.

[0203] FIG. 3 shows a schematic illustration of a first exemplary production line for producing a glass tube element such as the glass tube element 101.

[0204] A glass tube line 111 formed by some forming device 113 is redirected into a horizontal direction. The forming device 113 is not specified in more detail here, but it may be designed for conducting for example a Danner process or a Vello process.

[0205] It is acknowledged that the glass tube element is part of the glass tube line 111. Alternatively it might be stated that the glass tube element during its production process is connected to further glass tube elements in one piece. From the glass tube line 111 subsequently glass tube elements, such as the glass tube element 101, are confectioned.

[0206] Therefore, even if reference is made to the glass tube line 111, the person skilled in the art clearly understands that every treatment the glass tube line 111 undergoes is also applied to the glass tube elements because these elements correspond to respective sections of the glass tube line 111. Vice versa the same is true: If it is stated that a glass tube element is treated somehow, this is the same as if the glass tube line, from which the glass tube element has been confectioned, is treated that way (unless otherwise stated or evident from the context).

[0207] Starting from a Position of x=0 (see FIG. 3) the glass tube line 111 runs in a horizontal direction parallel to the x axis corresponding to a defined path of movement. The glass tube line 111 has a defined speed of movement, preferably of 30 cm/s. The glass tube line 111, hence the glass tube element corresponding to the respective section of the glass tube line 111, passes with the defined speed of movement through a cooling device 115, for setting up a locally modified cooling rate of the glass tube line 111 (hence the glass tube elements). The glass tube line 111 has at least temporarily a surface temperature of between Tg−50 and Tg+150 degrees C. while passing through/along the cooling device 115. Tg means the transition temperature.

[0208] The cooling device 115 has a plurality of four contacting devices 117a-117d. Each contacting device 117a-117d is designed in form of a castor. The contacting devices 117a-117d has at least from time to time direct contact with at least one area of the outer surface of the glass tube line 111 (hence the corresponding glass tube elements).

[0209] To be more precise, the four contacting devices 117a-117d comes in contact with the outer surface of the glass tube element (i.e., the respective section of the glass tube line 111) one after another in time. A section of the class tube line 111 corresponding to a glass tube element such as the glass tube element 101 first comes in contact with contacting device 117a, then with contacting device 117b, then with contacting device 117c, and finally with contacting device 117d. Of course, this does not exclude that more than one contacting device has contact at the same time with the outer surface.

[0210] The locally modified cooling rate of the glass tube line 111 is achieved by means of the contacting devices 117a-117d. The contacting devices 117a-117d all have, at least in the area where the glass tube line 111 is contacted, a thermal conductivity of between 1 and 100 W/(m*K). Indeed, it is preferably between 30 and 50 W/(m*K). This allows to manipulate and change the cooling rate.

[0211] Changing the cooling rate has been proven to lead to improved geometric parameters, hence, to improved values for the first and second ratios, hence to improved quality of the glass tube element.

[0212] The contacting devices 117a-117d are located at spatial positions P1 . . . P4 down along the path of movement in a consecutive manner. Each of two contacting devices arranged in a consecutive manner (i.e., preferably they are direct neighbors) have a center-center-distance, preferably measured along the path of movement, of 50 cm or less. Indeed, the center-center-distance is 50 cm. Further contacting devices 119a-119d are provided at spatial positions P5 . . . P8.

[0213] FIG. 4 shows a schematic cross-sectional view of a contacting device, such as castor, for example castor 117a. The view is obtained by a cutting plane perpendicular to the x axis in FIG. 2 such that the view comprises the center axis of the contacting device.

[0214] The castor 117a (and likewise castors 117b-117d) have a V-like recess, which allows to support and/or move the glass tube line 111 along the path of movement. This shaping allows that the contacting device, such as the castor 117a, has at the same time contact with two areas 121a, 121b of the outer surface of the class tube line 111 (hence the class tube elements) by respective contacting areas of the contacting device. The contacting areas and the areas of the outer surface 121a, 121b contacted by the contacting device 117a are separated from each other.

[0215] The areas 121a, 121b are produced by surface areas of the castors, i.e., the contacting areas, which have at least one point which in turn has a distance D/2 of 10 cm or less from the center axis of the castor 117a.

[0216] Once the glass tube line 111 (or a section thereof corresponding to a glass tube element) exits the cooling device 115, the glass tube line 111 has a surface temperature of less than Tg−50 degrees C. Of course, this is not necessary and it may still has a surface temperature of between Tg−50 and Tg+150 degrees C. However, in the preferred setup the temperature is below Tg−50 degrees C. This is true because in this case, subsequent contacts of the glass tube line 111 with other elements have no or no significant or at least no adverse effect on any preferred properties of the glass tube line 111 (hence, the glass tube elements).

[0217] Indeed, in the setup of FIG. 3, following the cooling device 115, the glass tube line 111 get in contact with the further castors 119a-119d provided at spatial positions P5 . . . P8 down along the path of movement in a consecutive manner. However, they might be different from the castors 117a-117d comprised by the cooling device 115 because they are not part of the cooling device 115 and are not used for manipulating the cooling characteristics of the glass tube line 111.

[0218] Of course, in other preferred embodiments the castors 119a-119d might correspond to contacting devises of a second cooling device.

[0219] As indicated by the circular arrow in FIG. 3, the glass tube line 111 is rotated during its period of cooling with a rotation speed of 1 round or more per second. Indeed, the glass tube line 111 is rotated the entire time until confectioning, hence, also during the period of cooling.

[0220] Downstream of some transport device 123, the glass tube line 111 is confectioned so that individual glass tube elements, such as the glass tube element 101, are obtained from that line with a desired length.

[0221] FIG. 5 shows a schematic illustration of a second exemplary production line for producing a glass tube element such as the glass tube element 101. Structural features of the second exemplary production line which are identical or similar to the structural features of the first exemplary production line are labeled in FIG. 5 with the same reference numerals, but with a single dash.

[0222] It is apparent that the second exemplary production line is largely similar to the first exemplary production line described with respect to FIG. 3. Therefore, only differences between the first and second exemplary production line need to be discussed here. In addition, reference can be made to the above explanations with respect to FIG. 3.

[0223] The production line of FIG. 5 comprises a cooling device 115′ which has a plurality of five contacting devices 117a′-117e′.

[0224] The contacting devices 117a′-117e′ are located at spatial positions P1′ . . . P5′ down along the path of movement in a consecutive manner. Each of two contacting devices arranged in a consecutive manner (i.e., preferably they are direct neighbors) have a center-center-distance, preferably measured along the path of movement, of 50 cm or less. Indeed, the center-center-distance is 30 cm.

[0225] This means, there has been added one contacting device 117e′. And the center-center-distance between adjacent contacting devices 117a′-117e′ has been reduced from 50 cm to 30 cm.

[0226] This setup allows an increased interaction between the cooling device 115′ and the glass tube line 111′ during the period of cooling.

[0227] It has been proven to be advantageous to apply such an increased interaction, even if it comes on cost of a larger setup. The resulting glass tube elements have improved geometric parameters, especially improved first and second ratios, hence to improved quality of the glass tube element.

[0228] The further castors 119a′-119e′ at spatial positions P6′ . . . P10′ are not comprised by the cooling device 115′.

[0229] FIG. 6 shows a schematic illustration of a third exemplary production line for producing a glass tube element such as the glass tube element 101. Structural features of the third exemplary production line which are identical or similar to the structural features of the first and/or second exemplary production line are labeled in FIG. 6 with the same reference numerals, but with a double dash.

[0230] It is apparent that the third exemplary production line is largely similar to the first and second exemplary production line described with respect to FIG. 3 and FIG. 5. Therefore, only differences between the first, second and third exemplary production line need to be discussed here. In addition, reference can be made to the above explanations with respect to FIG. 3 and FIG. 5.

[0231] The production line of FIG. 6 comprises a cooling device 115″ which has a plurality of five contacting devices 117a″-117e″ located at spatial position P1″ . . . P5″ down along the path of movement in a consecutive manner.

[0232] The plurality of contacting devices 117a″-117e″ can be grouped into two groups with respect to the aspects diameter and center-center-distance.

[0233] The first group comprises contacting devices 117a″-117d″ at spatial positions P1″ . . . P4″ and the second group comprises contacting device 117e″ at spatial position P5″. The contacting devices 117a″-117d″ of the first group have a smaller diameter than the contacting device 117e′ of the second group. The smaller diameter allows that the center-center-distance of adjacent contacting devices 117a″-117d″ is reduced to 3 cm.

[0234] This setup allows an increased interaction between the cooling device 115″ and the glass tube line 111″ during the period of cooling. It has been proven to be advantageous to have contacting devices which are closer together. Hence, by reducing the size, especially the diameter of a contacting device which is designed as a castor, more contacting devices can be applied during higher temperatures.

[0235] Since in the setup of FIG. 6 different castors are used, different interactions are obtained based inter alia on: Time of first contact and castor diameter.

[0236] FIG. 7 shows a schematic illustration of a fourth exemplary production line for producing a glass tube element such as the glass tube element 101. Structural features of the fourth exemplary production line which are identical or similar to the structural features of the first, second and/or third exemplary production line are labeled in FIG. 7 with the same reference numerals, but with a triple dash.

[0237] It is apparent that the fourth exemplary production line is largely similar to the first, second and third exemplary production line described with respect to FIG. 3, FIG. 5 and FIG. 6. Therefore, only differences between the first, second, third and fourth exemplary production line need to be discussed here. In addition, reference can be made to the above explanations with respect to FIG. 3, FIG. 5 and FIG. 6.

[0238] The production line of FIG. 7 comprises a cooling device 115′″ which has a plurality of six contacting devices 117a′″-117f′″ located at spatial positions P1′″ . . . P6″′ down along the path of movement in a consecutive manner.

[0239] The plurality of contacting devices 117a′″-117f″′ can be grouped into two groups with respect to the aspects diameter and center-center-distance.

[0240] The first group comprises contacting devices 117b′″-117d′″ at spatial positions P2″′ . . . P4″′ and the second group comprises contacting devices 117a′″ and 117f′ at spatial position P1′″ and P5″′. The contacting devices 117b′-117d″′ of the first group have a smaller diameter than the contacting devices 117a″′ and 117f″′ of the second group. The smaller diameter allows that the center-center-distance of adjacent contacting devices 117b′″-117d′″ is reduced to 3 cm.

[0241] The arrangement of the contacting devices 117a′″-117f′″ is such that the class tube line 111″′ comes in contact first with the contacting device 117a′″ of the second group than one after the other of contacting devices 117b″′-117d″′ of the first group and finally with contacting device 117e″′ of the second group.

[0242] In other words, the first interaction between the class tube line 111′″ and the cooling device 115′″ is by means of the contacting device 117a′″ which has a large diameter. Then the interaction takes place by means of the contacting devices 117b″′-117e′″ which have smaller diameters. Finally interaction takes place with the contacting device 117f′″ having a larger diameter.

[0243] This alternating interaction leads to improved geometric parameters and quality of the final glass tube element.

[0244] The further castors 119a′″-119d″′ at spatial positions P6′ . . . P10′ are not comprised by the cooling device 115″′.

[0245] FIG. 8 shows a schematic illustration of a fifth exemplary production line for producing a glass tube element such as the glass tube element 101. Structural features of the fifth exemplary production line which are identical or similar to the structural features of the first, second, third and/or fourth exemplary production line are labeled in FIG. 8 with the same reference numerals, but with a fourth-times dash.

[0246] The fifth exemplary production line is based particularly on the fourth exemplary production line described with respect to FIG. 7. Therefore, only differences between the fourth and fifth exemplary production line need to be discussed here. In addition, reference can be made to the above explanations with respect to FIG. 7.

[0247] The production line of FIG. 8 comprises a cooling device 115″″ which in turn has a plurality of seven contacting devices 117a″″-117f″″ located at spatial positions P1″′ . . . P6′″ down along the path of movement in a consecutive manner. Indeed, with 117a″″ two contacting devices located both at P1″″ are denoted which form a contacting device group. The contacting devices 117a″″ of the contacting device group are arranged in a rotationally symmetrical manner around the glass tube line 111 (hence, around glass tube element 101).

[0248] In other words, one of the two contacting devices 117a″″ are located horizontal above and the other horizontal below the glass tube line 111″″.

[0249] This is just a further design option for increasing the number of interaction elements, especially contacting devices. This allows that at spatial position P1″″ four contacting surfaces interact between the cooling device 115″″ and the glass tube line 111″″ with only little space requirements and consumption: Two contacting devices 117a″″ each having two contacting areas (see description with respect to FIG. 4).

[0250] The features disclosed in the description, the figures as well as the claims could be essential alone or in every combination for the realization of the invention in its different embodiments.

LIST OF REFERENCE NUMERALS

[0251] 1 Glass tube element [0252] 3 Shell [0253] 5 Lumen [0254] 7 Circle [0255] 9 Circle [0256] 11 Glass tube element [0257] 13 Support [0258] 15 Line [0259] 101 Glass tube element [0260] 103 Shell [0261] 105 Lumen [0262] 111, 111′, 111″, 111′″, 111″″ Glass tube line [0263] 113, 113′, 113″, 113′″, 113″″ Forming device [0264] 115, 115′, 115″, 115″′, 115″″ Cooling device [0265] 117a, 117a′, 117a″, 117a′″, 117a″″ Contacting device [0266] 117b, 117b′, 117b″, 117b′″, 117b″″ Contacting device [0267] 117c, 117c′, 117c″, 117c′″, 117c″″ Contacting device [0268] 117d, 117d′, 117d″, 117d′″, 117d″″ Contacting device [0269] 117e′, 117e″, 117e″′, 117e″″ Contacting device [0270] 117f″, 117f″″ Contacting device [0271] 119a, 119a′, 119a″, 119a′″, 119a″″ Contacting device [0272] 119b, 119b′, 119b″, 119b′″, 119b″″ Contacting device [0273] 119c, 119c′, 119c″, 119c′″, 119c″″ Contacting device [0274] 119d, 119d′, 119d″, 119d′″, 119d″″ Contacting device [0275] 119e′, 119e″, 119e′″, 119e″″ Contacting device [0276] 121a, 121b Contacting area [0277] 123, 123′, 123″, 123″′, 123″″ Transport device [0278] P1, P1′, P1″, P1″′, P1″″ Position [0279] P2, P2′, P2″, P2′″ P2″″ Position [0280] P3, P3′, P3″, P3′″, P3″″ Position [0281] P4, P4′, P4″, P4′″, P4″″ Position [0282] P5, P5′, P5″, P5′″, P5″″ Position [0283] P6, P6′, P6″, P6′″, P6″″ Position [0284] P7, P7′, P7″, P7′″, P7″″ Position [0285] P8, P8′, P8″, P8′″, P8″″ Position [0286] P9′, P9″, P9′″, P9″″ Position [0287] P10′, P10″, P10′″, P10″″ Position [0288] P11′″, P11″″ Position [0289] d Distance [0290] e Distance [0291] t Distance [0292] x, x′, x″, x′″, x″″ Axis [0293] D Distance [0294] R Direction [0295] T Thickness