WO2022191137A1

WO2022191137A1 - Burner, apparatus and method for processing a glass container

Info

Publication number: WO2022191137A1
Application number: PCT/JP2022/009759
Authority: WO
Inventors: Michael Droessler
Original assignee: Nipro Corp
Current assignee: Nipro Corp
Priority date: 2021-03-09
Filing date: 2022-03-07
Publication date: 2022-09-15
Anticipated expiration: 2023-09-09
Also published as: DE102021105613A1

Abstract

The invention relates to a burner, an apparatus and a method for processing a glass container. The burner comprises: - a nozzle (10) in which at least one opening (12; 16a,b) for ejecting a flame (F) is provided; - a connector (11a) configured to connect the nozzle (10) to a source of fuel, for example a combustible gas; - wherein the nozzle (10) has an elongate tubular shape having a predetermined diameter, and - wherein the opening (12; 16a,b) is arranged in the nozzle (10) in such a way that the flame (F) is ejected through the opening (12; 16a,b) at an ejection angle with respect to a longitudinal axis of the elongate tubular nozzle (10) of more than 0° and less than 180°.

Description

BURNER, APPARATUS AND METHOD FOR PROCESSING A GLASS CONTAINER

The present invention relates to a burner, an apparatus and a method for processing a glass container.

Background

Many glass containers, in particular medical glass containers such as syringes, vials, and cartridges are mainly made of borosilicate glass tubes. The tubes with a uniform thickness are heated to a softening temperature or higher by a combustion flame of combustible gas or other heating means. The desired shape is obtained by stepwise molding using jigs or some forming tools while maintaining the high temperature. It is known that when the glass tube is heated to a high temperature in this molding process, alkali metal compounds such as Na and K oxide and sodium/potassium borate contained in the glass component are sublimated from the heated glass surface. It is also known that when the heating is finished and the local temperature drops, those compounds condense and deposit on the glass surface mainly as a basic oxide. The basic oxide deposited on the glass surface adheres to the glass surface and weakens the bond of silicone oxide, which is the main constituent substance of the glass, and forms a so-called processing deterioration region consequently.

In medical glass containers, when the liquid of the contents comes into contact with the processing deterioration region on the surface of the container, basic oxides are eluted into the liquid and the pH of the liquid rises, which affects the stability of the contents. In addition, when the alkaline component elutes from the processed deterioration region, peeling of the fine glass often occurs. The exfoliated minute glass remains on the bottom of the container and contributes to foreign matter contamination. In view of the above, medical glass containers converted from a borosilicate glass tube are requested to meet the leaching standards of alkali components defined in ISO4802-1, IS04802-2, and the like.

On the other hand, in the glass syringe outer cylinder (syringe barrel) manufactured based on a relatively thin glass tube, it is necessary to cut out the glass tube to a standard length corresponding to the desired length of each syringe outer cylinder product. Conventionally, in this cutting process, cracks are generated from the scratches by giving a thermal shock after scratching the cut part of the glass tube, and the cracks progress over the entire circumference of the glass tube to be separated. The method has been widely used in the tube cutting process. However, fine particles of glass are also generated in the above process of cutting and separating the glass tube, which often cause the mixing of foreign substances into the product.

It is therefore an object of the invention to propose a device and a method that contribute to the removal or reduction of foreign substances such as fine powder caused by the separation of the glass tube, friction between the molding jig and the glass tube and the molding lubricant mixed in the molding process after cutting the glass tube.

According to the invention this object is achieved by a burner, comprising:
- a nozzle in which at least one opening for ejecting a flame is provided;
- a connector configured to connect the nozzle to a source of fuel, for example a combustible gas;
- wherein the nozzle has an elongate tubular shape having a predetermined diameter, and
- wherein the opening is arranged in the nozzle in such a way that the flame is ejected through the opening at an ejection angle with respect to a longitudinal axis of the elongate tubular nozzle of more than 0° and less than 180°.

The nozzle of the burner according to the invention can be inserted into any typical glass tube or other glass container as a consequence of its elongate tubular shape. Then at least a portion of an inner wall of the glass container, preferably the entire inner wall of the glass container, can be processed by means of the flame ejected through the at least one nozzle opening. The flame is fed by the combustible gas or other fuel provided by the source and arriving at the nozzle through the connector. Since the ejection angle of the flame with respect to the longitudinal axis of the elongate tubular nozzle is more than 0° and less than 180°, the ejected flame is not restricted to the longitudinal axis and can therefore reach almost any point on the inner wall of the glass container by carrying out an appropriate scanning of the flame.

The temperature of the inner surface of the glass tube by the flame treatment is preferably equal to or higher than the glass transition point, and may be a temperature that does not cause deformation of the glass. In the case of general borosilicate glass, it is preferably 525 °C or higher, more preferably 550 °C or higher, and even more preferably 575 °C or higher.

The irradiation time of the flame is not particularly limited as long as the desired effect can be obtained, but a preferred example is 3 to 15 seconds, more preferably 5 to 10 seconds. The irradiation time of the flame is appropriately adjusted so that the glass tube is not deformed and the effect is maximized.

The combustible gas serving as a fuel is preferably a hydrocarbon, preferably methane, ethane, propane, butane, pentane, and more preferably methane. Hydrogen and acetylene may also be envisaged. The fuel is supplied to the nozzle as a mixed gas with oxygen, and the respective flow rates and mixing ratios of the gas and oxygen can be appropriately selected according to the amount of heat required for processing the glass container. The mixing ratio of gas and oxygen is preferably a complete combustion ratio.

This heat treatment by flame processing allows to remove or at least reduce foreign particles like e.g. alkaline compounds deposited on the glass surface, and furthermore allows to burn or volatilize and thus remove fine glass particles.

In this context the glass container includes, but is not limited to, a glass container for pharmaceutical or medical purposes such as a vial, a syringe, or a cartridge, or an unmolded glass tube. Preferably, the glass container has a tubular shape. In particular the glass container should be suitable for containing and storing pharmaceutical products.

Advantageously the flame ejection angle of the burner is less than or equal to 90°, preferably between 15° and 90°, more preferably between 25° and 85°, in particular 30°. In this case the flame is ejected well away from the nozzle allowing to reach the entire inner wall of the glass container.

The at least one opening can be provided in a tip wall and/or a sidewall of the nozzle. Providing the at least one opening in the tip wall makes it easier to also treat the small opposing part of the inner wall of the glass container which faces the tip of the nozzle when inserted into the glass container. On the other hand, providing the at least one opening in the side wall of the nozzle makes it easier to treat the larger part of the inner wall of the glass container that surrounds the nozzle when inserted.

In a preferred embodiment of the burner according to the invention, a plurality of openings are therefore provided in the nozzle, the openings having identical or different ejection angles. As an example, at least one opening may be located in the tip wall whereas at least one further opening is provided in a side wall of the nozzle. This allows treating more than one point on the inner wall of the glass container by flame processing at the same time.

In a special case of this preferred embodiment the openings are located at equally or unequally spaced positions in a circumferential direction of the nozzle. In this case, the openings form a kind of “ring” along the circumference of the nozzle allowing to apply the flame processing to a ring-shaped portion of the inner wall of the glass container at the same time.

In this case, a first group of openings can be provided at a first distance from a tip wall of the nozzle having a first uniform spacing in the circumferential direction, and a second group of openings can be provided at a second distance from the tip wall having a second uniform spacing in the circumferential direction. In this case, the openings form two rings along the circumference at different positions on the nozzle allowing to apply the thermal processing to an even larger portion of the inner wall of the glass container at the same time.

In this case, the first uniform spacing can advantageously equal the second uniform spacing, and the openings of the second group can be offset, in the circumferential direction, from the openings of the first group by half the uniform spacing. This allows obtaining a particularly uniform flame treatment of the inner wall of the glass container such as to avoid excessive temperature differences.

The nozzle of the burner according to the invention can be made from ceramic, titanium, steel, stainless steel, brass or other heat resisting materials. Ceramic is preferred in very high temperature applications since it is very heat resistant.

Advantageously the at least one opening has a diameter up to 5 mm, preferably up to 0,5 mm. This allows obtaining a well-defined flame for heat processing. The diameter of the at least one opening should not be smaller than e.g. 0,1 or 0,2 mm.

The invention furthermore provides an apparatus for processing a glass container, comprising:
- the burner as proposed above;
- a holder for holding the glass container;
- a moving mechanism configured to carry out a relative movement between the burner and the glass container such that the nozzle of the burner penetrates into the glass container.

The moving mechanism can in particular move the burner into the glass container while the latter is held fixedly by the holder. During this penetration movement the burner can already be switched on and eject a flame so that a portion of the inner wall of the glass container is evenly and entirely processed by the flame.

In a simple embodiment of the apparatus according to the invention, the relative movement is a translation. In this case, the portion of the inner wall of the glass container which is processed by the flame during the penetration movement is a linear portion.

Preferably the apparatus according to the invention furthermore comprises a rotation mechanism configured to carry out a relative rotation between the nozzle and the glass container. This relative rotation can result from a rotation of the nozzle while the glass container is fixedly held and/or from a rotation of the glass container while the nozzle is fixedly held. In any case, the relative rotation allows applying the flame processing to a circumferential portion of the inner wall of the glass container. Combining the moving mechanism and the rotation mechanism allows applying the flame processing to all parts of the inner wall of the glass container.

The rotation mechanism is preferably configured to carry out the relative rotation at constant angular speed. In this case, a uniform application of heat to all parts of the inner wall of the glass container can be assured.

In a preferred embodiment the apparatus according to the invention furthermore comprises a preheating module configured to heat up the glass container. Such preheating makes it easier to achieve the necessary temperatures for removing or at least reducing foreign particles like e.g. alkaline compounds deposited on the glass surface, and furthermore for burning or volatilizing and thus removing fine glass particles by the flame processing.

The object of the invention is furthermore achieved by a method for processing a glass container, comprising the following steps:
- inserting a nozzle of a burner as proposed above into the glass container;
- processing at least a portion of an inner wall of the glass container by means of the flame ejected through the at least one nozzle opening; and
- removing the nozzle from the glass container.

As explained above in connection with the burner, the temperature of the inner surface of the glass tube to be achieved by the method according to the invention is preferably equal to or higher than the glass transition point, and may be a temperature that does not cause deformation of the glass. In the case of general borosilicate glass, it is preferably 525 °C or higher, more preferably 550 °C or higher, and even more preferably 575 °C or higher.

The irradiation time of the flame to be selected for the method according to the invention is not particularly limited as long as the desired effect can be obtained, but a preferred example is 3 to 15 seconds, more preferably 5 to 10 seconds. The irradiation time of the flame is appropriately adjusted so that the glass tube is not deformed and the effect is maximized.

The method according to the invention allows removing or at least reducing alkaline compounds deposited on the glass surface, and furthermore allows burning or volatilizing and thus removing fine glass particles on the inner wall of the glass container.

In a preferred embodiment of the method according to the invention the processing step comprises a step of scanning the flame on the inner wall of the glass container. This allows positioning the flame ejected by the nozzle on all parts of the inner wall of the glass container that require a heat processing.

Advantageously the scanning step comprises carrying out a relative rotation between the nozzle and the glass container. Carrying out such a relative rotation while the nozzle is switched on and ejects a flame allows treating a circumferential portion of the inner wall of the glass container by flame processing. This relative rotation can result from a rotation of the nozzle while the glass container is fixedly held and/or from a rotation of the glass container while the nozzle is fixedly held.

In this latter case, the relative rotation is preferably achieved by rotating the glass container around a longitudinal axis thereof, wherein the longitudinal axis of the elongate tubular nozzle is parallel to or forms an acute angle with the longitudinal axis of the glass container. Setting the longitudinal axes of the nozzle and the glass container parallel to each other allows using a relatively simple moving mechanism and/or rotation mechanism and is particularly suitable when the glass container has an essentially elongate cylindrical shape. However, when the glass container has a rather bulbous shape setting an angle between the nozzle and the glass container will make it easier to reach all points on the inner wall of the glass tube during the flame treatment. The angle should be rather small, i.e. an acute angle, in order to make sure that the tip of the nozzle does not contact the inner wall of the glass container.

In all embodiments of the method according to the invention that make use of the scanning step this scanning step preferably comprises carrying out a relative translation between the nozzle and the glass container. Such relative translation can in particular comprise a linear movement of the nozzle into the glass container at the beginning of the flame processing and out of the glass container at the end of the flame processing.

Preferably a distance between the inner wall of the glass container and a tip of the nozzle is kept constant in the scanning step. This avoids undesired temperature fluctuations and reduces the risk of mechanically damaging the glass container due to contact with the nozzle tip. In practice some distance variations are acceptable as long as it is made sure that all parts of the inner wall of the glass container are sufficiently flame-treated and no mechanical damage occurs.

In a similar manner, an angle formed by the axis of the glass container and the axis of the nozzle in the longitudinal direction is preferably kept constant in the scanning step. This also avoids undesired temperature fluctuations and reduces the risk of mechanically damaging the glass container due to contact with the nozzle. In practice some angle variations are acceptable as long as it is made sure that all parts of the inner wall of the glass container are sufficiently flame-treated and no mechanical damage occurs.

In all embodiments of the method according to the invention the processing step is advantageously carried out in such a way that a temperature of the inner wall of the glass container caused by the flame processing is equal to or higher than the glass transition point.

Preferred embodiments of the burner, the apparatus and the method for processing a glass container according to the invention will be described in the following with reference to the attached drawings, in which:

Figs. 1a, b, c show a schematic cross-sectional view of a hollow glass container during its flame treatment by means of a processing method according to the invention using a burner according to the invention;

Figs. 2a, b, c show a schematic perspective view, cross-sectional view and top view, respectively, of a nozzle of a first embodiment of a burner according to the invention;

Figs. 3a, b show a side view and a cross-sectional view, respectively, of a nozzle of a second embodiment of a burner according to the invention;

Fig. 4 schematically illustrates relative movements between the nozzle and the glass container carried out during the processing method according to the invention;

Fig. 5 shows a schematic perspective view of a moving mechanism and a rotating mechanism of a first embodiment of a processing apparatus according to the invention; and

Fig. 6 shows a schematic perspective view of a moving mechanism and a rotating mechanism of a second embodiment of a processing apparatus according to the invention.

Detailed Description of Embodiments

Figs. 1a, b, c schematically illustrate steps of a processing method according to the invention using a burner according to the invention. The burner of this embodiment comprises a nozzle 10 that has an elongate tubular shape having a predetermined diameter in which a plurality of openings for ejecting flames F are provided. Two such flames F can be seen in Figs. 1a, b, c being ejected at the right end of the nozzle 10. The flames result from the combustion of a combustible gas provided from a source of combustible gas (not shown in the figures) and fed into the nozzle 10 via a connector at the left end of the nozzle 10 in these figures (also not shown). The tubular-shaped nozzle 10 is inserted into a hollow glass container 20 which is also essentially tube-shaped and has a larger diameter than the nozzle 10. Depending on the combustible gas used in the burner, the flames F may reach temperatures up to approximately 3000 °C and therefore allow to remove or at least reduce foreign substances from the cylindrical inner wall of the hollow glass container 20 by treating them. In all figures the glass container 20 is a syringe barrel having a wide opening 20a through which, during later use, a syringe piston can be introduced, and a narrow opening 20b at which a needle can be fixed.

At the beginning of the method for processing the glass container 20 the nozzle 10 is inserted into the glass container 20 at its wide opening 20a and moved towards its narrow opening 20b. In Fig. 1a this movement from left to right is indicated by an arrow. During this movement the burner is active, i.e. the nozzle 10 ejects flames F that hit the inner side wall of the glass container 20.

Fig. 1b shows a subsequent situation close to the maximum penetration of the nozzle 10 into the glass container 20. In this situation the flames F hit the inner end wall of the glass container 20 converging towards the narrow opening 20b.

Fig. 1c shows a subsequent step in which the nozzle 10 is being pulled out of the glass container 20 while still being active. This movement from right to left is again indicated by an arrow

The steps schematically shown in Figs. 1a, b, c may be carried out repeatedly, i.e. the nozzle 10 of the burner according to the invention is inserted into and pulled out of the glass container 20 several times in succession. Throughout this method according to the invention the burner is active, i.e. the nozzle 10 ejects flames F that hit the inner wall of the glass container 20 and burn or volatilize foreign substances and/or little glass particles adhering thereto. Repeated and fast execution of these method steps is preferred over a single and slower execution in order to reduce the risk of local overheating.

Figs. 2a, b, c show a schematic perspective view, cross-sectional view and top view, respectively, of an end of a nozzle 10 of a first embodiment of a burner according to the invention. This end corresponds to the right end of the nozzle 10 in Figs. 1a, b, c.

The nozzle 10 has three openings 12 located at equal angular distances in a tip wall 14 of the nozzle 10. During use of the burner according to the invention a flame will be ejected out of each opening 12. The ejection angle with respect to the longitudinal axis of the nozzle 10 is schematically shown in the cross-sectional view of Fig. 1b where the longitudinal axis of the nozzle 10 is indicated by a dot and dash line. The ejection angle of a flame from each opening 12 is determined by the inclination of the tip wall 14 with respect to the longitudinal axis and by the bore angle of the respective opening 12 in the tip wall 14.

The size of a flame from each opening 12 is essentially determined by the diameter of the respective opening 12. Diameters may be in a range up to 5 mm, preferably up to 0,5 mm.

Figs. 3a, b show a side view and a cross-sectional view, respectively, of a nozzle 10 of a second embodiment of a burner according to the invention. In this embodiment the tip wall 14 is straight, i.e. it is oriented at an angle of 90° with respect to the longitudinal axis of the nozzle 10, and it is closed, i.e. it does not have an opening. Instead, two groups of

openings

16a, 16b arranged like ,,rings'' are provided in a side wall 18 of the nozzle 10. Thus this embodiment of the nozzle 10 will allow to eject two rings of flames from the side wall 18.

In this embodiment each ring-shaped group comprises six openings 16a,b in the side wall 18 located at equally spaced positions in a circumferential direction of the nozzle 10. The first group of openings 16a is provided at a larger distance from the tip wall 14 of the nozzle 10 than the second group of openings 16b. The openings 16a,b of both groups have the same uniform spacing in the circumferential direction. The openings 16b of the second group are offset, in the circumferential direction, from the openings 16a of the first group by half the uniform spacing. This allows obtaining a regular heat distribution in the two rings of ejected flames so as to avoid local overheating when the inner side walls of the glass container 20 are flame-treated.

The cross-sectional view in Fig. 3b is taken with the nozzle 10 cut in a plane that contains its longitudinal axis and through two of the six openings 16b. It can be seen that each opening 16b corresponds to a bore through the side wall 18 oriented at an angle of 30° with respect to the longitudinal axis of the nozzle 10 which is again indicated by a dot and dash line. The entire ring-shaped second group of openings 16b therefore ejects a ring of flames at an opening angle of 60°.

The opening angle of the openings 16a may be different but is preferably the same as for the openings 16b in view of a regular heat distribution in the two rings of ejected flames.

The cleaning pattern, i.e. the pattern of all portions on the inner wall of the glass tube where foreign substances are removed or at least reduced, will depend, among others, on the number of flames ejected from the nozzle 10, their distribution in the circumferential and longitudinal direction of the nozzle 10 and the relative movement of the nozzle 10 with respect to the glass container 20.

In connection with the schematic illustration of the method according to the invention in Figs. 1a, b, c only a linear movement of the nozzle 10 into and out of the glass container 20 has been considered so far.

When a nozzle 10 according to the first embodiment shown in Figs. 2a, b, c and having three openings 12 in its tip wall 14 is used, such a simple translation of the nozzle 10 into and out of the glass tube 20, either once or several times, will essentially lead to a cleaning pattern with three clean streaks on the inner wall of the glass tube 20. Between these streaks there will still be a considerable amount of foreign substances and/or little glass particles. Contrary hereto, when a nozzle 10 according to the second embodiment shown in Figs. 3a, b and having two rings of six openings 16a, b in its side wall 18 is used, even such a simple linear translation of the nozzle 10 into and out of the glass tube 20, either once or several times, will lead to a much more regular cleaning pattern on the inner walls of the glass tube 20.

In order to further improve the cleaning pattern the relative movement of the nozzle 10 with respect to the glass container 20 may not be limited to a translation. Fig. 4 schematically illustrates more complicated relative movements between the nozzle 10 and the glass container 20 carried out during an improved embodiment of the processing method according to the invention.

In this improved embodiment the relative movement between the nozzle 10 and the glass container 20 comprises a linear translation of the nozzle 10 into and out of the glass container as well as a rotation of the glass container 20 around the nozzle 10. Both movements are indicated in Fig. 4 by respective arrows. This improved embodiment of the processing method according to the invention allows to scan the flame(s) F so as to treat every point of the inner wall of the glass container 20 and burn or volatilize foreign substances and/or little glass particles.

This holds true for any kind of burner according to the invention that is used in the heat processing. In Fig. 4 a burner having a nozzle 10 similar to the first embodiment shown in Figs. 2a,b,c ejecting three flames F is used. Alternatively the nozzle 10 according to the second embodiment shown in Figs. 3a,b may be used. Since the at least one

opening

12, 16a,b is arranged in the nozzle 10 in such a way that the at least one flame F is ejected through the

opening

12, 16a,b at an ejection angle with respect to the longitudinal axis of the elongate tubular nozzle 10 of more than 0° and less than 180°, each point of the inner wall of the glass container 20 can be reached by the flame(s) F by choosing an appropriate combination of a linear translation of the nozzle 10 into and out of the glass container and a rotation of the glass container 20 around the nozzle 10. In other words, a perfect cleaning pattern can be achieved that does not leave any remaining foreign substances and/or glass particles on the inner wall of the glass container 20.

Fig. 5 shows a schematic perspective view of a first embodiment of a processing apparatus 30 according to the invention that is configured to carry out the improved embodiment of the processing method as shown in Fig. 4. The apparatus 30 comprises a moving mechanism 32 comprising a sliding carriage 32a that is driven to execute a linear reciprocating motion and to which the nozzle 10 is attached. In the schematic illustration of Fig. 5 the moving mechanism 32 is an eccentric crank shaft mechanism well-known to the skilled person. The reciprocating movement of the sliding carriage 32a is indicated by a double arrow. The attachment of the nozzle 10 to the sliding carriage 32a is with an orientation such that the tube-shaped nozzle 10 reciprocates along its longitudinal axis represented by a dot and dash line in Fig. 5.

Fig. 5 also schematically shows a a connector 11a attached to the end of the nozzle 10 opposite to its tip wall 14, e.g. by means of a screw coupling or a snap-fit coupling. The connector 11a connects the nozzle 10 to a source of combustible gas (not shown) via a hose 11b. The hose 11b is flexible in order to compensate for the linear reciprocating movement of the nozzle 10 resulting from its attachment to the sliding carriage 32a.

The connector 11a allows to replace a nozzle 10 by another nozzle, e.g. when a glass container 20 of some different type or different diameter is to be treated. As a result, the nozzle 10 is configured to be replaceable with respect to the burner main body.

The apparatus 30 furthermore comprises a rotating mechanism 34 to which a holder 36 that firmly holds the glass container 20 is attached. The rotating mechanism 34 and the holder 36 can also be seen from a different perspective and enlarged in Fig. 4. The holder 36 holds the glass tube 20 in such an orientation that it is rotated, by the rotating mechanism 34, about its longitudinal axis represented by a dashed line in Fig. 5. This rotation of the rotating mechanism 34, the holder 36 and thus the glass tube 20 is indicated in Figs. 4, 5 by an arrow.

The rotating mechanism 34 and the moving mechanism 32 of the apparatus 30 are aligned such that the reciprocating nozzle 10 of the burner penetrates into the glass container 20 along its longitudinal axis. In other words, the longitudinal axes of the nozzle 10 and the glass container 20 are parallel and coincide.

Reciprocating the nozzle 10 into and out of the glass tube 20 along its longitudinal axis while simultaneously rotating the glass tube 20 about its parallel longitudinal axis allows to scan the flame(s) F on the entire inner wall of the glass container 20 so as to treat every point thereon and burn or volatilize foreign substances and/or glass particles. The rotating mechanism 34 rotates the glass tube 20 at constant angular speed so as to render the heat treatment of its inner wall by the flames F uniform by suppressing the generation of spots in which heat is unevenly concentrated. The angular speed is appropriately selected depending on, among others, the diameter of the

opening

12, 16a,b of the nozzle 10, the flow rate of fuel gas, the size and the wall thickness of the glass product 20 to be treated.

Fig. 6 shows a schematic perspective view of a moving mechanism 32 and a rotating mechanism 34 of a second embodiment of a processing apparatus 30 according to the invention. Contrary to the first embodiment shown in Fig. 5, the moving mechanism 32 of this embodiment is configured such that the reciprocating nozzle 10 of the burner penetrates into the glass container 20 along its longitudinal axis setting an acute angle, i.e. a small angle between the nozzle axis and the glass container axis. Consequently, the nozzle 10 has a slightly oblique orientation when penetrating into the glass container 20. In this second embodiment of the processing apparatus 30 according to the invention the tip wall 14 of the nozzle 10 is therefore located closer to the inner wall of the glass container 20 than in the first embodiment of Fig. 5. This is particularly advantageous in case of bulbuous glass containers 20 in order to make sure that a flame F ejected from the tip wall 14 can also reach corner regions between a bottom and the side walls of the glass container 20 which might otherwise be difficult to treat by the flame F.

For this purpose it would be sufficient to simply misalign the rotating mechanism 34 and the moving mechanism 32 of the apparatus 30 such that the reciprocating nozzle 10 of the burner penetrates into the glass container 20 at the acute angle, i.e such that the nozzle axis and the glass container axis include the acute angle. Rotating the glass container 20 by means of the rotating mechanism 34 about its longitudinal axis while linearly reciprocating the nozzle by means of the moving mechanism 32 would then allow to reach all corner regions between a bottom and the side walls of the glass container 20, in particular if the rotation caused by the rotating mechanism 34 is relatively fast compared to the translation of the nozzle 10.

However, the second embodiment of the processing apparatus 30 according to the invention shown in Fig. 6 is equipped with further components in order to make sure that the flame treatment will not miss any points on the inner wall of the glass container. In detail:

In this embodiment the nozzle 10 is not fixedly attached to the sliding carriage 32a but rather via an additional eccentric rotating drive 38 that rotates the end of the nozzle 10 where the connector 11a is attached. The eccentric rotating drive 38 supports the nozzle 10 via a decoupling ball bearing 40 with an external ball joint to prevent the nozzle 10 from rotating about its longitudinal axis.

Furthermore a movable ball joint 42 with a hole mounted to the tip of the sliding carriage 32a, i.e. the end of the sliding carriage 32a adjacent to the rotating mechanism 34, supports the nozzle 10 such that it can reciprocate into and out of the glass container 20 while simultaneously being rotated by the eccentric rotating drive 38. Thus the eccentric rotating drive 38 imparts a pivoting movement to the nozzle 10 so that its tip wall 14 moves on the surface of a cylindrical cone, in addition to its linear back and forth movement caused by the moving mechanism 32. The rotation direction of the eccentric rotating drive 38 is opposite to the rotation direction of the rotating mechanism 34 to increase the overlapping rate of the flame trajectory, as is schematically indicated in Fig. 6 by respective arrows.

The second embodiment of Fig. 6 improves the scanning of the flame F without any gaps on the inner wall of the glass container 20.

In all its embodiments the apparatus 30 may furthermore be equipped with a preheating module, e.g. a hot air supply (not shown) configured to heat up the glass container 20 to a temperature of approximately 450 °C in order to facilitate the flame processing.

In all the above embodiments the nozzle 10 has an essentially cylindrical shape. This is, however, not mandatory. The requirement for the nozzle to have an elongate tubular shape having a predetermined diameter can also be fulfilled if the nozzle is e.g. tapered with a smaller diameter at its tip wall 14 and a larger diameter at its opposite end where the connector 11a is attached, as long as it is assured that the flame(s) ejected from the nozzle inserted into the glass tube 20 can reach all points on the inner wall of the glass tube 20.

In particular, the outer diameter of the nozzle 10 and its length in the axial direction are set in consideration of the inner diameter and the length of the hollow body 20 to be processed. The outer diameter of the nozzle 10 is set so that at least the tip wall 14 thereof can be inserted into the internal space from the opening 20a of the hollow body 20. Specifically, the outer diameter of the nozzle 10 is sufficiently smaller than the inner diameter of the opening 20a, preferably by 1 to 30 mm in diameter, and more preferably by 2 to 10 mm.

Further, the length in the axial direction of the nozzle 10 is set to a length at which its tip wall 14 can reach the vicinity of the bottom of the hollow body 20 close to its narrow opening 20b. Specifically, the length of the nozzle 10 is longer than the depth of the hollow body 20.

In all theses arrangements the flame(s) F can be uniformly irradiated to the inner surface of the hollow glass body 20 in the flame treatment. Consequently with the burner, the apparatus and the method for processing a glass container of the present invention, a hollow glass product 20 can be obtained in which impurities such as glass fine powder and lubricant generated during processing of the glass tube 20 are extremely reduced or removed. In particular, a hollow glass product 20 in which alkali elution from the inner surface of the glass is reduced can be obtained.

Claims

A burner, comprising:
- a nozzle (10) in which at least one opening (12; 16a,b) for ejecting a flame (F) is provided;
- a connector (11a) configured to connect the nozzle (10) to a source of fuel, for example a combustible gas;
- wherein the nozzle (10) has an elongate tubular shape having a predetermined diameter, and
- wherein the opening (12; 16a,b) is arranged in the nozzle (10) in such a way that the flame (F) is ejected through the opening (12; 16a,b) at an ejection angle with respect to a longitudinal axis of the elongate tubular nozzle (10) of more than 0° and less than 180°.
A burner according to claim 1, wherein the ejection angle is less than or equal to 90°, preferably between 15° and 90°, more preferably between 25° and 85°, in particular 30°.
A burner according to any of the preceding claims, wherein the at least one opening (12; 16a,b) is provided in a tip wall (14) and/or a side wall (18) of the nozzle (10).
A burner according to any of the preceding claims, wherein a plurality of openings (12; 16a,b) are provided in the nozzle (10), the openings (12; 16a,b) having identical or different ejection angles.
A burner according to the preceding claim, wherein the openings (16a,b) are located at equally or unequally spaced positions in a circumferential direction of the nozzle (10).
A burner according to the preceding claim, wherein a first group of openings (16a) is provided at a first distance from a tip wall (14) of the nozzle (10) having a first uniform spacing in the circumferential direction, and a second group of openings (16b) is provided at a second distance from the tip wall (14) having a second uniform spacing in the circumferential direction.
A burner according to the preceding claim, wherein the first uniform spacing equals the second uniform spacing, and wherein the openings of the second group (16b) are offset, in the circumferential direction, from the openings of the first group (16a) by half the uniform spacing.
A burner according to any of the preceding claims, wherein the nozzle (10) is made from ceramic, titanium, steel, stainless steel or brass.
A burner according to any of the preceding claims, wherein the at least one opening (12; 16a,b) has a diameter up to 5 mm, preferably up to 0,5 mm.
An apparatus for processing a glass container (20), comprising:
- the burner according to any of the preceding claims;
- a holder (36) for holding the glass container (20);
- a moving mechanism (32) configured to carry out a relative movement between the nozzle (10) of the burner and the glass container (20) such that the nozzle (10) penetrates into the glass container (20).
An apparatus according to the preceding claim, wherein the relative movement is a translation.
An apparatus according to claim 10 or 11, furthermore comprising a rotation mechanism (34) configured to carry out a relative rotation between the nozzle (10) and the glass container (20).
An apparatus according to the preceding claim, wherein the rotation mechanism (34) is configured to carry out the relative rotation at constant angular speed.
An apparatus according to any of claims 10 to 13, furthermore comprising a preheating module configured to heat up the glass container (20).
A method for processing a glass container (20), comprising the following steps:
- inserting a nozzle (10) of a burner according to any of claims 1 to 9 into the glass container (20);
- processing at least a portion of an inner wall of the glass container (20) by means of the flame (F) ejected through the at least one nozzle opening (12; 16a,b); and
- removing the nozzle (10) from the glass container (20).
A method according to the preceding claim, wherein the processing step comprises a step of scanning the flame (F) on the inner wall of the glass container (20).
A method according to the preceding claim, wherein the scanning step comprises carrying out a relative rotation between the nozzle (10) and the glass container (20).
A method according to the preceding claim, wherein the relative rotation is achieved by rotating the glass container (20) around a longitudinal axis thereof, wherein the longitudinal axis of the elongate tubular nozzle (10) is parallel to or forms an acute angle with the longitudinal axis of the glass container (20).
A method according to any of claims 16 to 18, wherein the scanning step comprises carrying out a relative translation between the nozzle (10) and the glass container (20).
A method according to any of claims 16 to 19, wherein a distance between the inner wall of the glass container (20) and a tip of the nozzle (10) is kept constant in the scanning step.
A method according to any of claims 16 to 20, wherein an angle formed by the axis of the glass container (20) and the axis of the nozzle (10) in the longitudinal direction is kept constant in the scanning step.
A method according to any of claims 15 to 21 wherein the processing step is carried out in such a way that a temperature of the inner wall of the glass container (20) caused by the flame processing is equal to or higher than the glass transition point.