Method for controlling shape uniformity in glass tube converting process

Abstract

A method for producing a glass article from a glass tube includes the steps of securing the glass tube in a holder of a converting device; rotating the glass tube; and passing the glass tube through processing stations, including at least a heating station and a forming station, to form one or more features on the working end of the glass tube. The active time is the amount of time the glass tube is engaged with a heating element or forming tool while in the processing station, and the exposure index of the processing station is the product of the rotational speed of the glass tube multiplied by the number of heating elements or forming tools in the processing station multiplied by the active time. The absolute value of the difference between the exposure index and the nearest integer is less than or equal to 0.30, reducing temperature and dimensional non-uniformities around the glass tube.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Patent Application No. 63 / 064,631, filed August 12, 2020, the contents of which are relied upon and incorporated herein by reference in their entirety. [Technical Field]

[0002] The present disclosure relates generally to systems and methods for producing glass articles from glass tubes, and more particularly to systems and methods for controlling shape uniformity in glass tube conversion processes. [Background technology]

[0003] Historically, glass has been used as a preferred material for pharmaceutical packaging due to its hermeticity, optical clarity, and superior chemical durability compared to other materials. Specifically, glass used in pharmaceutical packaging must have adequate chemical durability so as not to affect the stability of the pharmaceutical formulations contained therein. Glasses with adequate chemical durability include glass compositions within the ASTM standard "Type IA" and "Type IB" glass compositions, which have a proven track record of chemical durability.

[0004] Glass tubing can be converted into other glass articles, such as various glass containers for use in pharmaceutical applications, including, but not limited to, vials, syringes, ampoules, cartridges, and other glass articles. Glass tubing can be converted, for example, in a "converter." Converters have been in use for over 75 years and are currently manufactured by various commercial and internal equipment suppliers. These converters typically reshape long lengths of glass tubing into multiple glass articles using steps including flame working, rotary and stationary tool forming, heat separation, or scoring and impact cutting steps. Various burners and forming tools are often used to form one or more articles from the glass tubing and to separate the articles from the glass tubing. Summary of the Invention [Problem to be solved by the invention]

[0005] During the conversion process, thermal and dimensional non-uniformities around the glass tube are a concern, potentially resulting in mass and shape asymmetries in the forming process for producing glass articles from the glass tube. These concerns become particularly pronounced as process throughput increases. These concerns can also arise when increasing the size of the glass tube, such as increasing the outer diameter. Throughout the process of converting the glass tube into one or more articles, the glass tube rotates around its central axis. To increase process throughput, the time the glass tube spends at each processing station is reduced. Additionally, as the outer diameter of the glass tube increases, the rotation speed of the glass tube generally decreases. In both situations, the number of rotations of the glass tube at each processing station may decrease, potentially leading to temperature and dimensional non-uniformities around the glass tube during forming. Temperature and dimensional non-uniformities can result in mass and shape asymmetries in the finished product produced from the glass tube. Therefore, there is a need for a system and method for converting glass tubes into glass articles, such as pharmaceutical packaging, while reducing temperature and dimensional variations around the glass tube. [Means for solving the problem]

[0006] In a first aspect of the present disclosure, a method for producing a plurality of glass articles from a glass tube may include securing the glass tube in a holder of a converting apparatus including a plurality of processing stations. The processing stations may include at least one heating station and at least one forming station. The method may further include rotating the glass tube within the holder about its central axis and passing the glass tube through each of the plurality of processing stations to form one or more features on the working end of the glass tube. For any of the plurality of processing stations, the active time of the processing station may be the amount of time the glass tube remains engaged with at least one heating element or at least one forming tool while in the processing station, and the exposure index of the processing station may be equal to the product of the rotational speed of the glass tube in the holder multiplied by the number of heating elements or forming tools in the processing station multiplied by the active time of the glass tube at the processing station, wherein the absolute value of the difference between the exposure index and the nearest integer is no greater than 0.30.

[0007] A second aspect may include the first aspect, further including the steps of identifying temperature or dimensional non-uniformities of the glass tube around the glass tube, determining an exposure index for the glass tube at one or more of the plurality of processing stations, comparing the exposure index to the nearest integer, and adjusting the rotation speed of the glass tube, the active time, or both, to maintain an absolute value of the difference between the exposure index and the nearest integer of 0.30 or less.

[0008] A third aspect may include the first or second aspect, including maintaining the exposure index within ±0.30 of the nearest integer, and by maintaining the exposure index within ±0.30 of the nearest integer, rotational instability of the glass tube and fluctuations in temperature around the glass tube may be reduced.

[0009] A fourth aspect may include any of the first to third aspects, wherein the exposure index may be equal to an integer.

[0010] A fifth aspect may include any of the first to fourth aspects, wherein the conversion device may include a plurality of holders, and the method may include a step of securing a plurality of glass tubes in the plurality of holders, and a step of passing each of the plurality of holders and the plurality of glass tubes through a plurality of processing stations.

[0011] A sixth aspect is a method for determining an active time for each of a plurality of glass tubes in each of a plurality of processing stations. Stationarity of and adjusting the rotation speed of each of the plurality of glass tubes to maintain an absolute value of the difference between the exposure index and the nearest integer for each of the plurality of glass tubes at each of the plurality of processing stations at 0.30 or less, thereby reducing temperature and dimensional non-uniformity of the glass tubes around the glass tubes.

[0012] A seventh aspect may include any of the first through fifth aspects, including varying the active time of each of the plurality of glass tubes in one or more of the plurality of processing stations to maintain an absolute value of the difference between the exposure index and the nearest integer for each of the plurality of glass tubes in each of the plurality of processing stations at or below 0.30, thereby reducing temperature and dimensional non-uniformity of the glass tube around the glass tube.

[0013] An eighth aspect may include any of the first to seventh aspects, wherein each of the plurality of processing stations may be at a fixed position, and the conversion device may sequentially index the glass tube to each of the plurality of processing stations.

[0014] A ninth aspect may include any of the first to seventh aspects, wherein the conversion device is capable of continuously moving the glass tube through the processing stations, and wherein each of the plurality of processing stations is capable of moving in coordination with the movement of the glass tube during the active time.

[0015] In a tenth aspect of the present disclosure, a system for producing a plurality of glass articles from a glass tube may include a converting apparatus having a plurality of processing stations, which may include at least one heating station, at least one forming station, and a separation station. The system may further include a plurality of holders, each operable to secure a glass tube and rotate the glass tube about a central axis of the glass tube. The converting apparatus may be operable to move the plurality of holders and glass tubes through the plurality of processing stations. Each of the plurality of processing stations may have an exposure index defined as the product of the rotational speed of the glass tube in the holder (in revolutions per hour) multiplied by the number of heating elements or forming tools contacting the outer surface of the glass tube at the processing station multiplied by the active time of the glass tube at the processing station. The active time of a processing station may be the amount of time the glass tube maintains engagement with at least one heating element or at least one forming tool while in the processing station. The absolute value of the difference between the exposure index and the nearest integer may be less than or equal to 0.30 for each of the plurality of processing stations.

[0016] An eleventh aspect may include the tenth aspect, wherein the conversion device may be an index conversion device operable to index the glass tube through each of the plurality of processing stations.

[0017] A twelfth aspect may include the eleventh aspect, wherein the active time may be less than or equal to a dwell time of the conversion device.

[0018] A thirteenth aspect may include the tenth aspect, wherein the converting device may be a continuous converting device operable to continuously move the glass tube through a plurality of processing stations.

[0019] A fourteenth aspect may include any of the tenth to thirteenth aspects, wherein at least one heating station of the conversion device may include at least one swivel burner that may be operably coupled to a swivel burner actuator operable to rotate the swivel burner to engage and disengage with the glass tube in the at least one heating station, and wherein the active time of the glass tube in the at least one heating station may be varied.

[0020] A fifteenth aspect may include any of the tenth to thirteenth aspects, wherein at least one heating station of the conversion device may include a burner movement system operable to move at least one burner to engage and disengage horizontally or vertically with the glass tube, and wherein an active time of the glass tube in the at least one heating station may be varied.

[0021] A sixteenth aspect can include any of the first to fifteenth aspects, wherein at least one heating station of the converting device can include one, two, three, four, or more than four heating elements.

[0022] A seventeenth aspect may include any of the first to sixteenth aspects, wherein at least one forming station of the conversion device may include at least one forming tool operably coupled to a forming tool actuator that may be operable to move the forming tool into and out of engagement with the glass tube, and wherein an active time of the glass tube at the at least one forming station may be varied.

[0023] An 18th aspect may include any of the 10th to 17th aspects. The conversion device may include a measurement system that may be operable to determine a temperature of at least the glass tube surrounding the glass tube, a dimension of at least the glass tube, or a combination thereof.

[0024] A nineteenth aspect may include the eighteenth aspect, wherein the measurement system may be a thermal imaging system.

[0025] A twentieth aspect may include any of the first through nineteenth aspects, further including a system controller communicatively coupled to the conversion device. The system controller may include at least one processor and at least one storage medium containing computer-readable and executable instructions that, when executed by the processor, cause the system controller to automatically identify one or more temperature or dimensional non-uniformities of the glass tube around the glass tube, determine an exposure index for the glass tube for one or more of a plurality of processing stations, compare the exposure index for each of the one or more processing stations to a nearest integer, and adjust a rotational speed of the glass tube, an active time of the glass tube at a processing station, or both, to maintain an absolute value of a difference between the exposure index and the nearest integer of 0.30 or less.

[0026] A twenty-first aspect may include the twentieth aspect, wherein the computer-readable and executable instructions, when executed by a processor, can cause the system to adjust the rotation speed of the glass tube to adjust the exposure index of one or more processing stations.

[0027] A twenty-second aspect may include the twentieth or twenty-first aspect, wherein the computer-readable and executable instructions, when executed by a processor, can cause the system to adjust the active time at one or more processing stations to adjust the exposure index.

[0028] A twenty-third aspect may include the twenty-second aspect, wherein the conversion device may be an indexing conversion device operable to index the glass tube through each of a plurality of processing stations, and wherein the computer readable and executable instructions, when executed by a processor, may cause the system to automatically increase or decrease the dwell time of the conversion device to increase or decrease the active time of the glass tube at the plurality of processing stations.

[0029] A 24th aspect may include any of the 20th to 22nd aspects, wherein the computer-readable and executable instructions, when executed by a processor, can cause the system to automatically adjust the active time of at least one heating station by varying the timing of moving the heating element into and out of engagement with the glass tube.

[0030] A twenty-fifth aspect can include any of the second through twenty-fourth aspects, wherein at least one heating station can include a swivel burner operably coupled to a swivel burner actuator. The swivel burner actuator can be communicatively coupled to a system controller and operable to receive control signals from the system controller to pivot the swivel burner into and out of engagement with the glass tube.

[0031] A twenty-sixth aspect may include the twenty-fifth aspect, wherein the computer-readable and executable instructions, when executed by a processor, can cause the system to automatically vary the timing of rotating the swivel burner to engage and disengage with the glass tube, thereby varying the active time of the glass tube at the heating station.

[0032] A 27th aspect may include any of the 1st to 26th aspects, wherein at least one forming station may include at least one forming tool operably coupled to a forming tool actuator, and the forming tool actuator may be communicatively coupled to a system controller and may be operable to receive one or more control signals from the system controller and move the forming tool into and out of engagement with the glass tube.

[0033] A twenty-eighth aspect may include the twenty-seventh aspect, wherein the computer-readable and executable instructions, when executed by a processor, can cause the system to automatically vary the timing of moving the forming tool to engage and disengage with the glass tube to vary the active time of the glass tube at the forming station.

[0034] A twenty-ninth aspect may include any of the twentieth through twenty-eighth aspects, wherein the conversion device may include a measurement system disposed proximate at least one heating station, at least one forming station, or both, and the measurement system may be communicatively coupled to the system controller and operable to measure at least one property of the glass tube surrounding the glass tube and transmit a signal to the system controller indicative of the property.

[0035] A thirtieth aspect may include the twenty-ninth aspect, wherein the at least one characteristic of the glass tube may include at least one temperature, at least one dimension, or both, of the glass tube.

[0036] A thirty-first aspect may include the twenty-ninth or thirtieth aspect, wherein the computer-readable and executable instructions, when executed by a processor, cause the system to automatically receive signals from a measurement system indicative of one or more characteristics of the glass tube, determine variability in the characteristics of the glass tube around the glass tube, and adjust the active time at the processing station, the rotation speed of the glass tube about a central axis, or both, to change the exposure index in response to the variability in the characteristics of the glass tube.

[0037] It should be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments described herein and, together with the description, serve to explain the principles and operation of the claimed subject matter. [Brief explanation of the drawings]

[0038] [Figure 1]1 is a schematic diagram of an embodiment of a converting apparatus for producing glass articles from glass tubes according to one or more embodiments shown and described herein; [Figure 2] 2 is a schematic top view of a primary turret, a secondary turret, and a feed turret of the conversion apparatus of FIG. 1 according to one or more embodiments shown and described herein; [Figure 3A] 2 is a schematic diagram of a heating station of the conversion apparatus of FIG. 1 according to one or more embodiments shown and described herein. [Figure 3B] 2 is a schematic diagram of a forming station of the converting apparatus of FIG. 1 according to one or more embodiments shown and described herein; [Figure 3C] 1 according to one or more embodiments shown and described herein. [Figure 3D] 2 is a schematic diagram of a cooling station of the conversion apparatus of FIG. 1 according to one or more embodiments shown and described herein. [Figure 3E] 2 is a schematic diagram of a separation station of the conversion apparatus of FIG. 1 according to one or more embodiments shown and described herein. [Figure 3F] 2 is a schematic diagram of a drilling station of the conversion apparatus of FIG. 1 according to one or more embodiments shown and described herein; [Figure 4] 2 is a schematic perspective view of a cross section of a glass tube before conversion in the conversion device of FIG. 1 according to one or more embodiments shown and described herein; [Figure 5] 1 is a graph showing the change in surface temperature (y-axis) of the inner and outer surfaces of a glass tube processed in a heating station as a function of holder rotation speed (x-axis) at a constant residence time, according to one or more embodiments shown and described herein. [Figure 6A] 2 is another schematic front view of the heating station of the conversion apparatus of FIG. 1 according to one or more embodiments shown and described herein; [Figure 6B] 6B is a schematic top view of the heating station of FIG. 6A according to one or more embodiments shown and described herein; [Figure 7]10 is a schematic top view of another heating station of the converting apparatus of FIG. 1 having two heating elements, according to one or more embodiments shown and described herein; [Figure 8] 10 is a schematic top view of yet another heating station of the converting apparatus of FIG. 1 having three heating elements, according to one or more embodiments shown and described herein; [Figure 9A] 2 is a schematic front view of a forming station of the converting apparatus of FIG. 1 according to one or more embodiments shown and described herein; [Figure 9B] 9B is a schematic top view of a forming station of the converting apparatus of FIG. 9A according to one or more embodiments shown and described herein; [Figure 10] 6B is a graph showing the relative length dimension (y-axis) of a glass tube processed in the heating station of FIG. 6A as a function of the exposure index (x-axis) of the glass tube at a constant residence time, according to one or more embodiments shown and described herein. [Figure 11] 6B is a graph showing the relative flange thickness (y-axis) of glass vials produced from glass tubes processed in the heating station of FIG. 6A as a function of the exposure index of the glass tubes (x-axis) at a constant residence time, according to one or more embodiments shown and described herein. [Figure 12] 1 is a schematic top view of a main turret having 18 processing stations according to one or more embodiments shown and described herein; DETAILED DESCRIPTION OF THE INVENTION

[0039] Reference will now be made in detail to embodiments of systems and methods for controlling shape uniformity and reducing dimensional variability in glass articles produced from a conversion process for converting glass tubing into glass articles, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used throughout the drawings to refer to identical or similar parts. A method disclosed herein for producing multiple glass articles from glass tubing may include securing the glass tubing in a holder of a converting apparatus including multiple processing stations, which may include at least one heating station and at least one forming station. The method may further include rotating the glass tubing about a central axis of the glass tubing within the holder, and passing the glass tubing through each of the multiple processing stations to form one or more features on a working end of the glass tubing. For any of the multiple processing stations, the active time of the processing station may be the amount of time the glass tubing maintains engagement with at least one heating element or at least one forming tool while in the processing station. The exposure index of a processing station may be equal to the product of the rotational speed (in revolutions per second) of the glass tube in the holder multiplied by the number of heating elements or forming tools in the processing station multiplied by the active time of the glass tube at the processing station. For any of the multiple processing stations, the absolute value of the difference between the exposure index and the nearest integer may be 0.30 or less. Maintaining the absolute value of the difference between the exposure index and the nearest integer at 0.30 or less reduces temperature and dimensional non-uniformities around the glass tube. Various methods of producing glass articles from glass tubes are described herein with particular reference to the accompanying drawings.

[0040] Directional terms used herein (e.g., up, down, right, left, front, back, upper, bottom) are made solely with reference to the depicted figures and the coordinate axes provided therewith and are not intended to imply absolute directions.

[0041] Unless otherwise expressly stated, it is in no way intended that any method described herein be construed as requiring that its steps be performed in a particular order or that an apparatus require a particular orientation. Thus, where a method claim does not actually recite the order its steps are to follow, or an apparatus claim does not actually recite an order or orientation for individual components, or where the claims or specification otherwise expressly state that the steps are to be limited to a particular order, or where no particular order or orientation for the apparatus components is recited, no order or direction is intended to be inferred in any sense. This applies regardless of any implicit basis for interpretation, such as: logical considerations regarding the arrangement of steps, operational flow, component order, or component direction; plain meaning derived from grammatical organization or punctuation; and the number or type of embodiments described in the specification.

[0042] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" element includes aspects having two or more such elements unless the context clearly dictates otherwise.

[0043] As used herein, the "working end" of the glass tube is the end of the glass tube that faces the processing station of the conversion device relative to the holder, and the "non-working end" of the glass tube is the end of the glass tube that faces away from the processing station.

[0044] As used herein, the "dwell time" of a conversion device refers to the amount of time a glass tube spends at a particular processing station before moving on to the next subsequent processing station.

[0045] As used herein, the term "active time" refers to the time that a glass tube remains engaged with at least one heating element or at least one forming tool while in a particular processing station.

[0046] When used in connection with the heating station, "engaging" the burner 302 with the glass tube 102 may refer to positioning the burner 302 so that a flame from the burner 302 extends toward or contacts the glass tube 102 to heat it. Conversely, when the burner 302 is not engaged with the glass tube 102, the burner 302 is positioned so that the flame from the burner 302 is directed away from the glass tube 102, or is positioned far enough away from the glass tube 102 so that the flame does not contact or directly heat the glass tube 102. Even when the burner 302 is not engaged with the glass tube 102, some heat transfer from the burner 302 to the glass tube 102 may occur, but this heating is incidental and minimal compared to the heating of the glass tube 102 when the burner 102 is engaged with the glass tube 102. The term "engage" mentioned above with respect to the burner 302 applies equally to other types of heating elements 301.

[0047] When used in reference to a forming tool 324 in a forming station 204, the term "engaged" refers to the forming tool 324 contacting the glass tube 102. When the forming tool 324 is disengaged, the forming tool 324 does not contact the glass tube 102.

[0048] As used herein, the term "part rate" refers to the production or throughput rate of a converting device in terms of number of glass articles per unit time.

[0049] As used herein, the term "perimeter" of a glass tube refers to a set of points on the glass tube 102 spanning 360 degrees at a certain radius r from the central axis D of the glass tube 102 at a particular Z position (i.e., a position on the ±Z axis in the figure). The circumference of the glass tube 102 may coincide, for example, with the outer surface 140 of the glass tube 102 at a particular Z position or the inner surface 146 of the glass tube 102 at a specific Z position.

[0050] Glass tubing can be converted into glass articles, particularly glass articles for use in pharmaceutical applications, including, but not limited to, vials, syringes, ampoules, cartridges, and other glass articles. Glass tubing can be converted into these glass articles using a converting device, such as a converter, that includes multiple processing stations. The processing stations can include heating stations, forming stations, thermal separation stations, and perforation stations, among other types of processing stations. Converters typically reshape long lengths of glass tubing into multiple glass articles using steps that include, but are not limited to, flame processing, rotary and stationary tool forming, thermal separation, or scoring and impact cutting steps. Thus, glass articles produced by the converting process performed in a converter are subjected to a series of flame burners or other heating elements and shaping tools to form the glass tubing into specific shapes and dimensions, and the shaped articles are separated from the glass tubing.

[0051] Referring now to FIG. 1 , a converting apparatus 100 for producing glass articles from glass tubes 102 is schematically depicted. The converting apparatus 100 can be used to convert the glass tubes 102 into a plurality of glass articles. The converting apparatus 100 can include a base 104 having a plurality of processing stations 106 and a main turret 108 positioned on the base 104 and rotatable relative to the base 104 about a central axis A. The converting apparatus 100 can further include a glass tube loading turret 110 positioned above the main turret 108 for feeding the glass tubes 102 to the main turret 108. The converting apparatus 100 can also include a plurality of secondary processing stations 112 on the base 104 and a secondary turret 114, which can be rotatable relative to the base 104.

[0052] As shown generally in FIG. 1 , the base 104 of the conversion apparatus 100 may be stationary, and the processing stations 106 may be coupled to an upper portion 105 of the base 104. The processing stations 106 may be spaced apart and arranged on a main circuit 116. In one or more embodiments, the main circuit 116 may be circular such that the main turret 108 can index or sequentially move the glass tubes 102 through the processing stations 106 by rotating the main turret 108 about a central axis A. Alternatively, in other embodiments, the main circuit 116 may be linear. While described herein with reference to a circular layout of the processing stations 106, it should be understood that the subject matter disclosed herein may be equally applicable to conversion apparatuses having other arrangements of the processing stations 106, such as linear, curvilinear, or irregularly shaped arrangements of the processing stations 106.

[0053] The type and / or shape of the article to be produced from the glass tube 102 may affect the number of processing stations 106 in the converting apparatus 100. The number of processing stations 106 in the main turret 108 may be between 14 and 32 processing stations 106. While the converting apparatus 100 and converting process are described herein with reference to a converting apparatus 100 having 16 processing stations 106 within the main circuit 116, it should be understood that the converting apparatus 100 may have more or fewer than 16 processing stations 106 within the main circuit 116. The processing stations 106 may include, by way of example and not limitation, one or more heating, forming, polishing, cooling, separating, punching, measuring, feeding, ejection stations, other processing stations, or combinations thereof, for producing glass articles from the glass tube 102. The type and / or shape of the article to be produced from the glass tube 102 may also affect the type of processing stations 106 and / or the sequence of the processing stations 106 in the converting apparatus 100.

[0054] The main turret 108 may be positioned on the base 104 and may be rotatably coupled to the base 104 such that the main turret 108 is rotatable about a central axis A relative to the base 104. A drive motor (not shown) may be utilized to rotate the main turret 108 relative to the base 104. The main turret 108 may include a plurality of holders 130 configured to removably secure each glass tube 102 to the main turret 108. The holders 130 may be clamps, chucks, or other holding devices, or a combination of holding devices. The holders 130 may orient each glass tube 102 so that the glass tube 102 is approximately parallel to the central axis A of the main turret 108 and approximately perpendicular to the top 105 of the base 104. While the conversion apparatus 100 is described herein with reference to a vertically oriented converter 100, it should be understood that the converter 100 may also be oriented horizontally or at an angle. Each of the holders 130 may extend from the bottom 109 of the main turret 108 in a direction toward the base 104 (i.e., the −Z direction relative to the coordinate axes of FIG. 1 ), and each holder 130 may orient the glass tube 102 at or adjacent each of successive processing stations 106 of the main circuit 116 of the base 104 as the main turret 108 is indexed about the central axis A. The vertical orientation of the glass tubes 102 allows the downwardly protruding portion of each glass tube 102 to be moved or indexed incrementally through the processing stations 106. In embodiments, the conversion apparatus 100 may be operable to incrementally index each of the multiple holders 130 through the multiple processing stations 106. Alternatively, in embodiments, the conversion apparatus 100 may be operable to move the multiple holders 130 sequentially through the conversion process. Each holder 130 may be individually rotatable relative to the main turret 108 to rotate the glass tube 102 about a central axis D of the glass tube 102, which may be generally parallel to a central axis A of the main turret 108. Each of the holders 130 may be operably coupled to a motor (not shown), a continuous drive belt, or other drive mechanism for rotation of each of the holders 130 relative to the main turret 108.Rotation of the holder 130 allows rotation of the glass tube 102 about its central axis D relative to a stationary burner, forming tool, cooling nozzle, or other feature of the processing station 106. The heating element or forming tool in the processing station 106 may be maintained in a fixed position relative to the glass tube 102, and rotation of the glass tube 102 about its central axis D may expose the entire circumference of the glass tube 102 to the heating element or forming tool.

[0055] 1 and 2, the converting apparatus 100 may include multiple secondary processing stations 112, which may be spaced apart and disposed within a secondary circuit 118 (FIG. 2). The converting apparatus 100 may include a secondary turret 114 (FIG. 1) for indexing or sequentially moving articles 103 (FIG. 1) separated from the glass tubes 102 through the multiple secondary processing stations 112. The secondary turret 114 may be rotatable about a second axis B relative to the base 104. The second axis B may be generally parallel to the central axis A of the main turret 108. The secondary turret 114 may also include multiple holders 130 for holding the glass articles 103 and positioning the glass articles 103 to sequentially engage with each of the secondary processing stations 112. The secondary turret 114 can receive the articles 103 from the separation station 206 (FIG. 2) of the main turret 108, index or sequentially move the articles 103 through multiple secondary processing stations 112 by rotation of the secondary turret 114, and eject the completed articles from the converting apparatus 100.

[0056] The glass tube loading turret 110 may be positioned adjacent to the main turret 108. In embodiments, the glass tube loading turret 110 may be offset from a central axis A of the main turret 108. The glass tube loading turret 110 may be rotatable about an axis C, which may be approximately parallel to the central axis A of the main turret 108. The glass tube loading turret 110 may be independently supported in a stationary position relative to the main turret 108, and the rotation of the glass tube loading turret 110 may be independent of the rotation of the main turret 108. Referring to FIGS. 1 and 2 , in some embodiments, the glass tube loading turret 110 may include a plurality of loading channels 132 arranged in a circular circuit 134 and configured to hold the glass tubes 102. The glass tube loading turret 110 can be positioned to align one of the loading channels 132 vertically (i.e., parallel to the central axis A of the main turret 108 and / or parallel to the Z-axis in FIG. 1 ) with a processing station 106 of the main circuit 116 of the conversion apparatus 100 and a corresponding holder 130 of the main turret 108 that moves through the processing station 106 of the main circuit 116. In one or more embodiments, the processing station 106 aligned with the glass tube loading turret 110 can be a tube loading station 214 ( FIG. 2 ). When the converting apparatus 100 has converted all or at least a portion of the glass tube 102 into one or more articles at a particular holder position 136, the glass tube loading turret 110 can deliver a new length of glass tube 102 to the holder 130 at the holder position 136 through the top of the main turret 108 when the holder position 136 is indexed to align with a tube loading station 214 ( FIG. 2 ) of the main circuit 116. In an alternative embodiment, the converting apparatus 100 can include an arm (not shown) movable between the main turret 108 and the glass tube loading turret 110. When the converting apparatus 100 has converted all or a portion of the glass tube 102 at a particular holder position 136, the arm can grab a new length of glass tube 102 from the glass tube loading turret 110 or other glass tube staging device and deliver the new length of glass tube 102 to the main turret 108 at the particular holder position 136.Other methods and apparatus for feeding new lengths of glass tube 102 into main turret 108 are also contemplated.

[0057] Referring to FIG. 2 , as described above, the multiple processing stations 106 of the converting apparatus 100 may include one or more heating stations 202, forming stations 204, separating stations 206, cooling stations 210, punching stations 212, tube loading stations 214, ejection stations 216, measuring stations 218, tube length drop stations 220, or other stations, and / or combinations of these stations. FIG. 2 schematically illustrates the arrangement of processing stations 106 for a converting apparatus 100 having a main circuit 116 of 16 processing stations 106 and a secondary circuit 118 of eight secondary processing stations 112. As described above, the processing stations 106 of the main circuit 116 may be evenly spaced and evenly distributed about the circular circuit, and the secondary processing stations 112 of the secondary circuit 118 may also be evenly spaced and evenly distributed about the circular circuit. FIG. 2 also schematically illustrates a glass tube loading turret 110 having multiple loading channels 132. 2, the glass tube loading turret 110 is shown in a position spaced apart from the main circuit 116 for purposes of illustration. Although the glass tube loading turret 110 is shown as having 24 loading channels 132, it should be understood that the glass tube loading turret can have more or less than 24 loading channels 132.

[0058] The main circuit 116 of the conversion apparatus, shown schematically in FIG. 2, may include one or more heating stations 202, a separating station 206, a punching station 212, one or more forming stations 204, one or more cooling stations 210, a measuring station 218, a tube length drop station 220, and a tube loading station 214. While FIG. 2 depicts the main circuit 116 as having a circular arrangement of processing stations 106, as previously discussed, the main circuit 116 may have processing stations 106 positioned in other geometric arrangements, such as linear, curved, irregular, or other configurations. With respect to the indexing direction 222 of the main turret 108, the heating station 202 is positioned before each of the forming station 204 and separating station 206 to preheat a target region of the glass tube 102 to a target temperature at which the target region becomes viscous and deformable, effectively forming or stretching the glass tube 102 and separating the glass tube 102. At the separation station 206, the formed glass article 103 (FIG. 1) can be separated from the glass tube 102 (FIG. 1) as its bottom is simultaneously formed. The separation station 206 may be the processing station 106 from which the partially formed glass article 103, once separated, is transferred to the secondary turret 114 (FIG. 1) and indexed through the secondary circuit 118 of the secondary processing station 112. The piercing station 212 can be located on the main circuit 116 downstream from the separation station 206, in the direction of index 222 of the main turret 108. At the piercing station 212, the meniscus 350 of the glass tube 102 previously formed at the separation station 206 is pierced, thereby reopening the working end 150 of the glass tube 102.

[0059] The forming station 204 of the main turret 108 can be positioned downstream of the punching station 212 and the one or more heating stations 202 in the index direction 222. The one or more forming stations 204 can repeatedly form the glass tube 102 to form one or more features of the finished glass article. As described above, one or more heating stations 202 can be positioned before each forming station 204 to preheat a target area of ​​the glass tube 102 to a temperature at which the glass tube 102 can be shaped and formed into a desired feature. The forming station 204 of the main turret 108 can form the working end 150 ( FIG. 3A ) of the glass tube 102 to form a feature on one end of the glass article 103, and the forming station 204 of the secondary turret 114 can form the other end of the glass article 103 after the glass article 103 is separated from the glass tube 102. In an embodiment, the conversion apparatus 100 can be used to produce vials from glass tubes 102, and the forming stations 204 of the conversion apparatus 100 can include one or more shoulder forming stations, flange forming stations, flange finishing stations, or combinations thereof, with one or more heating stations 202 positioned before and between each of the forming stations 204.

[0060] The main circuit 116 may further include a measurement station 218, where a dimensional measurement system (not shown) may be used to measure one or more dimensions of the glass tube 102, such as diameter and thickness, as well as one or more dimensions of features formed by the forming stations 204. The feature dimensions may include flange thickness, flange length, neck length, neck thickness, overall article length, other feature dimensions, or combinations thereof. The measurement station 218 may be positioned immediately after the last forming station 204 to measure dimensions while the glass tube 102 is still hot. Alternatively, the measurement station 218 may be positioned after one or more cooling stations 210 to measure dimensions of the glass tube 102 and / or glass article at a low temperature.

[0061] 2 , one or more cooling stations 210 may be positioned after the forming station 204 in the direction of index 222 of the main turret 108. After the forming station 204, a tube length drop station 220 may be positioned between the forming station 204 and the separation station 206 to drop the partially formed glass tube 102, thereby positioning the glass tube 102 for separation of the glass article 103 from the glass tube 102 at the separation station 206. The main circuit 116 may also include a tube loading station 214 for loading new lengths of glass tube 102 raw material from the glass tube loading turret 110 into the main turret 108 ( FIG. 1 ). In an embodiment, the tube loading station 214 may be incorporated into the cooling station 210. The tube loading station 214 may be positioned between the last forming station 204 and the separation station 206.

[0062] The forming station 204 of the main turret 108 can form features on a first end of the glass article 103. For example, the forming station 204 can form a shoulder 142 and a flange 144 on the top (first end) of the glass article 103, which is a vial or cartridge, as shown in FIG. 3A . Referring again to FIG. 2 , once the glass article 103 is separated from the glass tube 102 at the separation station 206, the glass article 103 can be transferred to a secondary processing station 112 of the secondary turret 114. The secondary processing station 112 can include one or more forming stations 204 for forming a second end of the glass article 103 opposite the first end of the glass article 103. For example, the forming station 204 of the secondary processing station 112 can form one or more features on the bottom (second end) of the glass article 103. The secondary turret 114 can rotate about axis B in a direction 224 opposite the main turret 108. In an embodiment, the secondary turret 114 can rotate in the same direction as the main turret 108 .

[0063] The secondary processing stations of the secondary circuit may include one or more heating stations 202, forming stations 204, polishing stations 208, cooling stations 210, discharge stations 216, or other stations, or combinations of secondary processing stations 112. While FIG. 2 depicts the secondary circuit as having secondary processing stations 112 in a circular arrangement, as previously discussed, the secondary circuit may have secondary processing stations 112 positioned in other shaped arrangements, such as linear, curved, irregularly shaped, or other arrangements. In embodiments, the secondary processing stations 112 of the secondary circuit 118 may be used to form one or more features of the glass article 103, such as a vial, an ampoule, a cartridge, or a syringe, on the end of the glass article 103 opposite the end formed by the main turret 108. For example, in some embodiments, the glass article 103 is a vial, and the forming station 204 of the secondary circuit 118 may form the bottom of the vial. Other features, such as features specific to ampoules, cartridges, syringes, etc., are also contemplated. The secondary circuit 118 may include one or more polishing stations 208 for finishing the surface of the glass articles. The secondary circuit 118 may further include multiple cooling stations 210 and a discharge station 216 where the finished glass articles 103 may be discharged from the converting apparatus 100.

[0064] The foregoing description of the processing stations 106 in the primary circuit 116 and the secondary processing stations 112 in the secondary circuit 118 may represent a typical converting apparatus 100 for producing vials from glass tubes 102. However, it should be understood that more or fewer processing stations 106 and secondary processing stations 112 may be utilized to produce vials having different shapes or features, or other glass articles, such as cartridges, syringes, ampoules, or other pharmaceutical glass articles. Furthermore, it should be understood that the processing stations 106 and secondary processing stations 112 may be arranged in any number of different orders and / or configurations to produce glass articles of different shapes.

[0065] Referring now to FIG. 3A, the heating stations 202 of the converting apparatus 100 are shown schematically. Each of the heating stations 202 may include one or more heating elements 301. As shown in FIG. 3A, in an embodiment, the heating elements 301 may include one or more burners 302 used to heat a target area of ​​the glass tube 102 prior to a forming operation performed in the forming station 204 (FIG. 2) or a separating operation performed in the separating station 206 (FIG. 2). While a single burner 302 is shown in FIG. 3A, it should be understood that multiple burners 302 may be used in a single heating station 202, as shown in FIGS. 6 and 7, which show two and three burners 302, respectively. Referring again to FIG. 3A, each burner 302 may be fluidly connected to a fuel supply 304, an oxygen supply 306, and, optionally, an air supply 308. Examples of fuels for the burners 302 include, but are not limited to, hydrogen, hydrocarbon fuel gases such as methane, propane, and butane, other fuels, or combinations thereof. Each burner 302 may include a fuel control valve 310 for controlling the flow of fuel gas to the burner 302. Each burner 302 may also include an oxygen control valve 312 for controlling the mass flow rate of oxygen to the burner 302. Each burner 302 may also optionally include an air control valve 314 for controlling the flow rate of air to the burner 302. The burners 302 combust the fuel gas in the presence of oxygen and / or air to generate a flame that heats at least a target area of ​​the glass tube 102. While the heating station 202 of the conversion apparatus 100 is described herein as using a burner to heat the glass tube 102, it should be understood that other heating elements or methods other than a burner may be used to heat the glass tube 102.

[0066] 3B and 3C, exemplary forming stations 204 of the converting apparatus 100 are schematically illustrated. Each forming station 204 may include one or more forming tools 324 rotatable relative to the base 104 (FIG. 1) about a tooling axis E. To move to a forming station 204, the glass tube 102, heated in the previous heating station 202, is rotated by the holder 130. As the forming tools 324 rotate, they may engage the outer surface 140 of the glass tube 102. Once engaged, contact between the forming tools 324 and the heated outer surface 140 of the glass tube 102 may form the glass tube 102 into a desired shape. The forming tools 324 may contact the glass tube 102 for an active time. Once the active time expires, a forming tool actuator 326 may disengage the forming tools 324 from the glass tube 102. FIG. 3B schematically illustrates an embodiment of a forming station 204 for forming a shoulder 142 of a glass vial formed from the glass tube 102. 3C schematically illustrates an exemplary embodiment of a forming station 204′ for forming the flange 144 of a glass vial formed from a glass tube 102. The forming station 204′ for forming the flange 144 includes three forming tools 324a, 324b, and 324c. Other types of forming tools 324 can be used in the forming station 204, depending on the desired features of the article.

[0067] 3D schematically illustrates the cooling station 210 having one or more cooling nozzles 340 positioned to direct a cooling fluid 342, such as cooling air or an inert gas, toward the glass tube 102. One or more of the cooling nozzles 340 may be positioned to direct the cooling fluid 342 to a specific region of the glass tube 102. One or more cooling fluid control valves 344 may be fluidly coupled to the cooling nozzles 340 to control the mass flow rate of the cooling fluid 342 to the cooling nozzles 340, thereby controlling the rate of cooling of the glass tube 102, as well as the temperature and temperature gradient of the glass tube 102.

[0068] Referring now to FIG. 3E, a separation station 206 of the converting apparatus 100 is shown schematically. The separation station 206 shown in FIG. 3E is a thermal separation station and may be positioned after one or more heating stations 202 in the indexing direction 222 of the main turret 108. The heating station 202 positioned before the separation station 206 heats the glass tube 102 to make the glass viscous. The separation station 206 may include a separation burner 348. The glass tube 102, rendered viscous and deformable by the previous heating station 202, is rotated about its central axis D by the holder 130 while the separation burner 348 engages with the outer surface 140 of the glass tube 102 to heat it to a temperature at which the viscosity of the glass causes the article to separate from the glass tube 102. Once separated from the glass tube 102, the article may be transferred to the secondary turret 114 (FIG. 1) or ejected from the converting apparatus 100. Although shown as a thermal separation station in FIG. 3E, separation station 206 may also be a non-thermal separation station, such as a separation station that uses scoring and breaking techniques, as may be used for syringes and cartridges, for example.

[0069] 3F, a typical piercing station 212 of the converting apparatus 100 is shown schematically. The piercing station 212 may be positioned after the separation station 206 in the indexing direction 222 of the main turret 108. As described above, thermal separation of the article 103 from the glass tube 102 at the separation station 206 creates a meniscus 350 of glass across the working end 150 of the glass tube 102. At the piercing station, the meniscus 350 is pierced in preparation for forming the next article at the working end 150 of the glass tube 102. The piercing station 212 may include a piercing burner 352. The piercing burner 352 may be positioned below and oriented toward the working end 150 of the glass tube 102. The piercing burner 352 may be fluidly connected to one or more of a fuel gas supply 304, an oxygen supply 306, an air supply 308, or a combination thereof. The fuel gas supply 304, oxygen supply 306, and air supply 308 were previously discussed with respect to the burner 302 of Figure 3A. When the main turret 108 indexes the glass tube 102 to the piercing station 212, a flame from the piercing burner 352 heats the meniscus 350 of the glass, melting the meniscus 350 and perforating the meniscus 350 and reopening the working end 150 of the glass tube 102. In embodiments, the meniscus 350 may be perforated by directing a gas flow, such as compressed air, nitrogen, argon, or other gas, at or across the meniscus 350. In embodiments, the meniscus 350 may be perforated using mechanical means or other methods.

[0070] 3A-3F include schematic diagrams of several different example processing stations 106 that may be utilized in converting apparatus 100. However, it should be understood that other processing stations 106 having different structures, combinations of structures, or functionality may be utilized to achieve the desired conversion of glass tube 102 into one or more glass articles.

[0071] Referring to FIG. 4, the glass tube 102 may be an elongated, hollow, cylindrical tube made of glass. The glass tube 102 may have a circular cross-sectional shape and may have an outer surface 140, an inner surface 146, and a thickness t. The thickness t of the glass tube 102 may be the radial distance between the inner surface 146 and the outer surface 140 of the glass tube 102. The glass tube 102 may have a length L in the ±Z direction of the coordinate axes of FIG. 4. The glass tube 102 may have an outer diameter OD as shown in FIG. 4. As previously discussed, the glass tube 102 is rotated about the central axis D of the glass tube 102 throughout the conversion process.

[0072] 1 and 2 , during operation, the main turret 108 can index or move the glass tube 102 secured in the holder 130 to the processing stations 106. A particular operation, such as heating, forming, piercing, separating, cooling, dropping, feeding, or measuring, can be performed on the glass tube 102 at each of the processing stations 106. As used herein, the “dwell time” of the converting apparatus 100 can refer to the time the glass tube 102 spends at a particular processing station 106 before being indexed by the main turret 108 to the next subsequent processing station 106. The converting apparatus 100 can be adjusted so that all processing stations 106 complete their operations within the dwell time. At the end of the dwell time, the main turret 108 can index the glass tube 102 to the next processing station 106. As used herein, "index time" may refer to the time it takes the main turret 108 to index a glass tube 102 from one processing station 106 to the next processing station 106, measured in units of time. In an indexing conversion system, the total time per part per station, as used in this disclosure, is the sum of the dwell time and the index time.

[0073] In embodiments, the converting apparatus 100 may be a continuous converting apparatus operable to continuously move the glass tube 102 and holder 130 through a plurality of processing stations 106. In embodiments, heating elements, burners, forming tools, measuring devices, and other elements of the converting process may move with the glass tube 102 as it passes through the processing stations 106. For both indexed converting apparatus and continuous converting apparatus, the active time of a processing station is the duration that the glass tube 102 maintains engagement with at least one heating element or at least one forming tool while in the processing station 106.

[0074] An example of a converting apparatus 100 for converting glass tubes 102 into glass vials includes a vial forming machine model RP16 or RP18 with an automatic tube feeder manufactured by AMBEG Dr. J. Dichter GmbH, which includes 16 processing stations 106 on a main circuit 116 and eight secondary processing stations 112. Other examples include a vial forming machine model RP32 manufactured by AMBEG Dr. J. Dichter GmbH, which has 32 processing stations 106 on a main circuit 116 and two secondary circuits 118 with eight secondary processing stations 112 in each secondary circuit 118, and a Zeta 098 vial forming machine manufactured by Euromatic SRL, which has 36 processing stations. Another example includes a converting apparatus for converting glass tubes into cartridges, the Zeta 103 cartridge forming machine manufactured by Euromatic SRL. Cartridge converting apparatuses have similar features to the vial converting apparatus 100 described above, but are utilized to produce glass articles having a cartridge form factor rather than a vial.

[0075] Although described in connection with converting apparatus 100 for producing glass vials from glass tubes 102, it should be understood that converting apparatus 100 may be configured to produce one or more other articles, such as other types of pharmaceutical containers or articles, by varying the forming tools 324 and / or the sequence or configuration of the processing stations 106 of the primary circuit 116 or the secondary processing stations 112 of one or more secondary circuits 118. Pharmaceutical articles may include, but are not limited to, vials, cartridges, syringes, ampoules, jars, or other glass pharmaceutical articles.

[0076] During the conversion process, thermal and dimensional non-uniformities around the glass tube 102 are a concern, potentially resulting in mass and shape asymmetries in the forming process for producing glass articles from the glass tube 102. These concerns have been observed to be particularly pronounced as process throughput increases and for articles produced from increasingly larger glass tubes (e.g., larger outer diameters (OD)). As previously discussed, the glass tube 102 is continuously rotated about its central axis D within the holder 130 as it passes through multiple processing stations 106. As the throughput of the converting apparatus 100 increases, the glass tube 102 may spend less time at each processing station 106. In an indexing converting apparatus 100, increasing the part rate throughput of the converting apparatus 100 may include decreasing the residence time, the index time, or both. In an embodiment, the index time may be generally fixed, and the part rate may be increased by decreasing the residence time of the glass tube 102 at each processing station 106. In a continuous converting apparatus, the part rate can be increased by increasing the speed at which the glass tube 102 passes through the series of processing stations 106. By decreasing the residence time in the indexed converting apparatus 100 or increasing the speed of the continuous converting apparatus, the amount of time the glass tube 102 spends at each processing station 106 can be decreased. As a result, the number of rotations of the glass tube 102 at each processing station 106 can be decreased for a given constant rotational speed of the glass tube 102.

[0077] When increasing the OD of the glass tube, the rotation speed of the glass tube 102 generally decreases as the outer diameter of the glass tube increases. However, at a constant throughput of the conversion apparatus 100, the rotation rate of the glass tube 102 in each processing station 106 may also decrease due to the decrease in the rotation speed of the glass tube 102 in the holder 130.

[0078] Thus, increasing the throughput rate of the converting apparatus 100, increasing the tube diameter or glass tube 102, or both, may cause a decrease in the number of rotations of the glass tube 102 within each processing station 106. Reducing the number of rotations of the glass tube 102 within a processing station 106 may also reduce the number of times that points on the exterior surface of the glass tube 102 engage with the burners 302 or forming tools 324 within the processing station 106. This can lead to temperature non-uniformities in the glass tube 102 around the glass tube 102 during forming, which can result in asymmetries in mass and shape in the finished article produced therefrom.

[0079] Fluctuations in glass tube temperature around the glass tube 102 and the resulting dimensional and cosmetic variations can constrain the operating window of the conversion process, reduce process capability (Cpk), reduce yield, or a combination thereof. Yield reduction can result from slowing down production rates to reduce yield losses due to temperature and / or dimensional non-uniformities around the glass tube 102 or dimensional and cosmetic variations that cause articles to be out of specification. For a given nominal vial or glass article size performed under certain processing conditions, yield losses due to dimensional and cosmetic variations caused by temperature fluctuations in the glass tube 102 during conversion can exceed 30%.

[0080] It has been discovered that certain combinations of part rate and rotation speed of the glass tube 102 within the holder 130 can result in highly unstable rotation of the heated portion of the glass tube 102, which may be referred to as the preform region of the glass tube 102. It has been observed that, at these certain combinations of part rate and rotation speed, the bottom of the preform region (i.e., the portion of the preform region in the -Z direction of the coordinate axes in the figure) can move significantly from side to side and up and down as the glass tube 102 rotates within the holder 130. This phenomenon is commonly referred to as "wobble" in the conversion process. The wobble can be most noticeable in the final heating station before forming or in processing stations after shoulder forming during the production of vials and cartridges. The wobble can be due to inconsistent heating of the glass tube 102 in the heating station 202, inconsistent contact with the forming tool in the forming station 204, or both.

[0081] These particular combinations of part rate and rotation speed of the glass tube 102 within the holder can result in temperature non-uniformities around the glass tube 102. Referring to FIG. 5, a graph shows the change in surface temperature (y-axis) of the inner (reference numeral 902) and outer (reference numeral 904) surfaces of a glass tube 102 being processed in the heating station 202 as a function of holder rotation speed (x-axis) at a constant dwell time. For FIG. 5, the heating station 202 has a single burner 302, and the dwell time is equal to the active time the burner 302 is engaged with the glass tube 102. The change in surface temperature is the absolute value of the difference between the maximum and minimum temperatures measured at the surface. As shown by the periodic peaks in FIG. 5, certain rotation speeds of the glass tube 102 at a constant dwell time result in substantially greater variations in surface temperature around the glass tube 102 for both the inner and outer surfaces of the glass tube 102. As previously discussed, this greater temperature variation at these rotational speeds can result in dimensional non-uniformity in the glass articles produced from the glass tube 102.

[0082] Thus, there remains a need for systems and methods for reducing or preventing temperature and / or dimensional non-uniformities around the glass tube 102 during conversion of the glass tube 102 into a glass article, particularly temperature and dimensional non-uniformities that may be caused by inconsistent heating or contact with forming tools in the processing station 106. The systems and methods of the present disclosure reduce or prevent temperature and dimensional non-uniformities in the preform region of the glass tube 102 around the glass tube 102 during heating, shaping, or both, by maintaining a combination of active time and rotational speed that results in consistent heating around the glass tube 102 in the heating station 202, consistent contact between the glass tube 102 and the forming tools 324 around the glass tube 102 in the shaping station 204, or a combination thereof. In particular, the systems and methods disclosed herein are directed to reducing the variability in the number of times each point on the outer surface of the glass tube 102 around the glass tube 102 engages with a heating element 301 in the heating station 202, the number of times it comes into contact with a forming tool 324 in the forming station 204, or both, during the active time of the glass tube 102 in the processing station 106.

[0083] The average number of times a point on the outer surface 140 of the glass tube 102 engages a heating element 301 or forming tool 324 at a particular processing station 106 can be characterized by an exposure index. The exposure index can be defined as the product of the rotational speed of the glass tube 102 in the holder 130 multiplied by the number of heating elements 301 or forming tools 324 contacting the outer surface 140 of the glass tube 102 in the processing station 106, and the active time of the glass tube 102 at the processing station 106. The exposure index I E can be represented by formula I (EQU. I).

[0084] I E =r×n×t A EQU.1 In EQU. 1, r is the rotation speed of the glass tube 102, n is the number of heating elements 301 or forming tools 324 that contact the outer surface 140 of the glass tube 102 in the processing station 106, and t Ais the active time of the glass tube 102 in the processing station 106. For a heating station 202 having multiple burners 302, EQU. 1 assumes that all of the multiple burners in the heating station 202 have the same heating rate. In a heating station 202 with multiple burners having different heating rates or a forming station 204 with two or more different forming tools, a scale factor may be included to account for the different heating rates of each burner or the different extent of contact with the forming tool. Alternatively, in embodiments where the heating station 202 includes multiple burners with different heating rates or the forming station 204 includes two or more different types of forming tools, n may be set to a value of 1 in EQU. 1. As previously discussed, the active time t A may be the total time that the glass tube 102 remains engaged with at least one heating element 301 or at least one forming tool 324 while in the processing station 106. In an indexing converting apparatus, the active time may be less than or equal to the dwell time of the converting apparatus 100.

[0085] The exposure index may indicate the average number of times each point on the circumference of the glass tube 102 at a Z position (e.g., a position along the ±Z axis in FIG. 4 ) is exposed to the heating element 301 or shaping tool 324 while in the processing station 106. The exposure of a point on the circumference of the glass tube 102 to the heating element 301 may refer to the point on the circumference of the glass tube 102 rotating into engagement with the heating element so that the heating element heats that point on the glass tube 102. The rotation of the glass tube 102 in the processing station 106 rotates each of the points on the circumference into successive engagement with the heating element 301. Similarly, in the forming station 204, the exposure of a point on the circumference of the glass tube 102 to the shaping tool 324 may refer to the point on the circumference of the glass tube 102 rotating into contact with the shaping tool 324 so that the shaping tool 324 deforms the glass at that point on the circumference of the glass tube 102.

[0086] It has been discovered that maintaining the exposure index as close to an integer as possible can reduce or prevent temperature and / or dimensional non-uniformities around the glass tube 102 during conversion. The converting apparatus 100 may have an exposure index such that the absolute value of the difference between the exposure index and the nearest integer is 0.30 or less, e.g., 0.25 or less, 0.20 or less, 0.15 or less, 0.10 or less, or even 0.05 or less. While not intending to be bound by theory, it is believed that when the exposure index is within 0.3 of the nearest integer, sufficient points around the circumference of the glass tube 102 have the same number of exposures to the heating elements or forming tools in the processing station 106, reducing or preventing rocking and resulting temperature and / or dimensional non-uniformities around the glass tube 102. Each exposure to the heating element 301 applies heat to the glass tube 102, thereby increasing the temperature of the glass. As the exposure index approaches an integer, a greater percentage of points along the circumference of the glass tube 102 may receive the same number of exposures to the heating element 301, resulting in a greater percentage of points around the glass tube 102 receiving the same amount of heat during the active time. Therefore, when the exposure index is within 0.30 of the nearest integer, heating may be more uniform around the glass tube 102, resulting in improved temperature and dimensional uniformity. In other words, when the exposure index is close to an integer, all of the circumference of the glass tube 102 receives substantially the same heat from the steady burner. In the case of the forming tool 324, heat is removed from the glass tube 102 by contact with the forming tool 324. Therefore, maintaining the exposure index close to an integer value in the forming station 204 can ensure that substantially the same heat is removed by the forming tool 324 for most points around the circumference of the glass tube 102.

[0087] When the exposure index of the converting apparatus 100 is within 0.30 of the nearest integer, 70% or more of the surrounding glass points have the same number of exposures to the heating elements or forming tools in the processing stations 106. When the exposure index of the converting apparatus 100 is within 0.25 of the nearest integer, 75% or more of the surrounding glass points have the same number of exposures to the heating elements or forming tools in the processing stations 106. When the exposure index of the converting apparatus 100 is within 0.20 of the nearest integer, 80% or more of the surrounding glass points have the same number of exposures to the heating elements or forming tools in the processing stations 106. When the exposure index of the converting apparatus 100 is within 0.10 of the nearest integer, 90% or more of the surrounding glass points have the same number of exposures to the heating elements or forming tools in the processing stations 106. When the exposure index of the converting apparatus 100 is equal to an integer, theoretically, 100% of the surrounding glass points have the same number of exposures to the heating elements or forming tools in the processing stations 106. Therefore, the closer the exposure index is to the nearest integer, the more consistent the heating or forming will be around the circumference of the glass tube 102 .

[0088] 6A and 6B, a heating station 202 having a single heating element 301 is depicted schematically in front and top views, respectively. When the heating station 202 has a single heating element 501, the number of heating elements in EQU. 1 is equal to 1. With a single heating element 501 in the heating station 202, the exposure index is equal to the rotational speed (revolutions per hour) of the glass tube 102 about the central axis D multiplied by the active time of the glass tube 102 engaged with the heating element 301. Thus, the exposure index of a heating station 202 with a single heating element 301 is equal to the number of rotations of the glass tube 102 during the active time, or the number of rotations per active time. For each complete rotation of the glass tube 102 during its active time in the heating station 202, each of the points around the glass tube 102 within the preform region 141 can pass into direct engagement with the heating element 301 at a time, such as by passing into alignment with line G at point H in FIG. 6B.

[0089] However, if the combination of the active time and the rotational speed of the glass tube 102 results in an additional partial rotation of the glass tube 102 at the end of the active time, a first portion of the circumference of the glass tube 102 will receive additional exposure to the heating element 301. The first portion of the circumference of the glass tube 102 that receives additional exposure to the heating element 301 may have a higher temperature compared to a second portion of the circumference of the glass tube 102 that does not receive additional exposure. Therefore, temperature non-uniformities around the glass tube 102 may occur, which can lead to wobbling and / or dimensional non-uniformities in the finished glass article made from the glass tube 102. The temperature and / or dimensional non-uniformities are greatest at half a rotation, where the first portion that receives additional exposure is equal to the second portion that does not receive additional exposure. It has been found that temperature and / or dimensional non-uniformities are reduced when the number of rotations per active time is within 0.30 or 0.25 of the nearest integer.

[0090] 7 and 8, in embodiments, the heating station 202 of the conversion apparatus 100 may have multiple heating elements 301, such as multiple burners 302. Referring to FIG. 7, a heating station 202 having two burners 302 radially spaced 180 degrees from each other is shown schematically. With two burners 302, each complete rotation of the glass tube 102 within the heating station 202 may result in each point on the outer surface 140 of the glass tube 102 being exposed to the burners 302 twice. Thus, the exposure index for a heating station 202 having two burners 302 may be equal to 2 (the number of burners 302) multiplied by the rotational speed of the glass tube 102 about the central axis D multiplied by the active time of the glass tube 102 in the heating station 202. With an exposure index equal to an integer, a point on the outer surface 140 of the glass tube 102 starting at point H will end up at point H or point J in FIG. 7 at the end of the active time. It has been found that this results in very small temperature and / or dimensional non-uniformities around the glass tube 102. When the exposure index is halfway between two integers, a point on the outer surface 140 of the glass tube 102 starting at point H will end up at either point I or point K in FIG. 7 at the end of the active time. Under these conditions, at point I or point K, the quarter of the glass tube 102 downstream of points I and K relative to the direction of rotation 148 receives extra exposure to one of the burners 302, while the quarter of the glass tube downstream of points I and K does not receive extra exposure. Therefore, temperature and / or dimensional non-uniformities may be greatest when the exposure index is halfway between two integers. Temperature and / or dimensional non-uniformities can be reduced by adjusting the exposure index so that the absolute value of the difference between the exposure index and the nearest integer is less than 0.30, 0.25 or less, 0.20 or less, 0.15 or less, 0.10 or less, or even 0.05 or less.

[0091] 8, a heating station 202 having three burners 302 equally spaced radially from one another is shown schematically. With three burners 302, each complete rotation of the glass tube 102 within the heating station 202 allows each point on the exterior surface 140 of the glass tube 102 to receive three exposures to the burners 302. Thus, n is equal to 3 in EQUATION 1, and the exposure index for a heating station 202 having three burners 302 may be equal to 3 multiplied by the rotational speed of the glass tube 102 about the central axis D multiplied by the active time of the glass tube in the heating station 202. More than three burners 302 within the heating station 202 are contemplated.

[0092] Temperature and / or dimensional non-uniformities around the glass tube 102 can be increased or decreased by adjusting the exposure index so that the absolute value of the difference between the exposure index and the nearest integer is less than 0.30, 0.25 or less, 0.20 or less, 0.15 or less, 0.10 or less, or even 0.05 or less. As previously discussed, the exposure index can be modified by changing the rotation speed of the glass tube 102 in the holder 130 or by adjusting the active time of the glass tube 102 in the processing station 106. In the heating station 202, the active time of the glass tube 102 can be changed by changing the dwell time of the conversion apparatus 100 or by moving the heating element 301 (e.g., burner 302) into and out of engagement with the glass tube 102 during the dwell time. The heating element 301 can be moved into and out of engagement with the glass tube 102 by pivoting the heating element 301 toward or away from the glass tube 102, by moving the heating element 301 toward or away from the glass tube 102, or both. Other methods of moving the heating element 301 into and out of engagement with the glass tube 102 are also contemplated.

[0093] Referring again to Figure 6B, in an embodiment, the burner 302 in the heating station 202 may be a swivel burner 330 operable to pivot laterally (e.g., in the XY plane according to the coordinate axes of Figure 6) about a vertical axis F to engage and disengage the glass tube 102. The swivel burner 330 may include a swivel burner actuator 332 operably coupled to the swivel burner 330. The swivel burner actuator 332 is operable to pivot the swivel burner 330 about the axis F to move the flame of the swivel burner 330 into and out of engagement with the glass tube 102. In Figure 6B, the swivel burner 330 is depicted in a position where the flame of the swivel burner 330 engages and heats the glass tube 102. In an engaged position with the glass tube 102, the flame of the swivel burner 330 may contact or point toward the glass tube 102. In an embodiment, in an engaged position with the glass tube 102, the swivel burner 330 and flame may be aligned along a line G extending through the axis of rotation D of the glass tube 102. In a disengaged position with the glass tube 102, the flame of the swivel burner 330 points away from the glass tube 102 so that the flame does not directly contact or point toward the glass tube 102. In an embodiment, when disengaged, the swivel burner 330 may be oriented so that it is not aligned with the line G that intersects the axis of rotation D of the glass tube 102. The burner 302 may also be operatively coupled to an actuator that moves the burner 302 toward or away from the glass tube 102 in the XY plane of Figure 6B, or moves the burner 302 vertically in the ±Z direction of Figure 6A to engage and disengage with the glass tube 102. Other methods of varying the active time are also contemplated.

[0094] 9A and 9B, a forming station 204 is shown schematically having two forming tools 324 in contact with the outer surface 140 of the glass tube 102. In contrast to a heating element 301, such as the burner 302 of FIGS. 7 and 8, contact between the forming tools 324 and the glass tube 102 may operate to reduce the temperature of the glass tube 102. The glass tube 102 entering the forming station 204 may have a higher temperature at the outer surface 140 compared to the surface temperature of the forming tools 324, allowing heat to be transferred from the glass tube 102 to the forming tools 324 via contact between the forming tools 324 and the glass tube 102. Temperature non-uniformities around the glass tube 102 may occur when some portions of the circumference of the glass tube 102 are more frequently exposed to the forming tools 324 than other portions of the circumference of the glass tube 102.

[0095] Dimensional non-uniformities around the circumference of the glass tube 102 can be caused by temperature non-uniformities around the glass tube 102 or by differences in glass displacement between points around the circumference of the glass tube 102 due to differences in the number of exposures to the forming tool 324. As previously discussed, contact with the forming tool 324 causes displacement of the glass of the glass tube 102 within the preform region to form one or more features of the finished glass article. Each exposure of a point around the circumference of the glass tube 102 to the forming tool 324 results in some deformation of the glass at that point. Thus, dimensional non-uniformities around the circumference of the glass tube 102 can occur when some portions of the circumference of the glass tube 102 experience greater exposure to the forming tool 324 and greater glass displacement compared to other portions of the circumference of the glass tube 102.

[0096] Similar to the heating station 302, temperature and / or dimensional non-uniformities around the glass tube 102 can be reduced in the forming station 204 by maintaining the exposure index of the glass tube 102 in the forming station 324 as close to an integer as possible. The forming station 204 can have an exposure index such that the absolute value of the difference between the exposure index and the nearest integer is 0.30 or less, e.g., 0.25 or less, 0.20 or less, 0.15 or less, 0.10 or less, or even 0.05 or less.

[0097] Referring to FIG. 9B , a forming station 204 having two forming tools 324 contacting the outer surface 140 of the glass tube 102 is shown schematically. The two forming tools 324 may be radially spaced 180 degrees apart from each other. With two forming tools 324, each complete rotation of the glass tube 102 in the forming station 204 may result in each point on the outer surface 140 of the glass tube 102 being exposed to the forming tools 324 twice. Thus, the exposure index of a forming station 204 having two forming tools 324 contacting the outer surface 140 of the glass tube 102 may be equal to 2 multiplied by the rotational speed of the glass tube 102 about the central axis D multiplied by the active time of the glass tube 102 in the forming station 204. With an exposure index equal to an integer, a point on the outer surface 140 of the glass tube 102 starting at point H will end up at either point H or point J in FIG. 9B at the end of the active time. It has been found that this results in significantly reduced temperature and / or dimensional non-uniformities around the glass tube 102. When the exposure index is halfway between two integers, the point on the outer surface 140 of the glass tube 102 ends up at either point I or point K in FIG. 9B at the end of the active time. Under these conditions, at point I or point K, a quarter of the glass tube 102 downstream of points I and K relative to the direction of rotation 148 receives extra exposure to one of the forming tools 324, while a quarter of the glass tube downstream of points I and K does not receive extra exposure. Thus, temperature and / or dimensional non-uniformities may be maximized when the exposure index is halfway between two integers. In an embodiment, the forming station 324 may include a third forming tool (e.g., forming tool 324c in FIG. 3C) inserted inside the glass tube 102. If the forming station 204 includes two forming tools 324 that contact the outer surface 140 of the glass tube 102 and a third forming tool that is inserted inside the glass tube 102, the exposure index is still equal to the product of 2 multiplied by the rotational speed of the glass tube 102 about the central axis D and the active time of the glass tube 102 in the forming station 204.

[0098] Temperature and / or dimensional non-uniformities around the glass tube 102 can be reduced by adjusting the exposure index so that the absolute value of the difference between the exposure index and the nearest integer is less than 0.30, 0.25 or less, 0.20 or less, 0.15 or less, 0.10 or less, or even 0.05 or less. The exposure index at the forming station 204 can be varied by changing the rotational speed of the glass tube 102 about the central axis D or by varying the active time that the forming tool 324 is engaged and / or in contact with the outer surface 140 of the glass tube 102. The active time can be varied by moving the forming tool 324 in and out of contact with the glass tube 102 to vary the active time.

[0099] 9A, in an embodiment, each of the shaping tools 324 may be operably coupled to a shaping tool actuator 326. The shaping tool actuator 326 may be operable to move the shaping tools 324 into and out of engagement with the glass tube 102. The timing of actuating the shaping tools 324 to engage and disengage with the glass tube 102 may be adjusted by varying the active time of the glass tube 102 in contact with the shaping tools 324.

[0100] 9A and 9B as having two forming tools 324, it should be understood that the forming station can swing more than two forming tools, for example, three, four, or more than four forming tools. In each case, the exposure index can be equal to the number of forming tools 324 contacting the outer surface 140 of the glass tube 102 multiplied by the rotational speed of the glass tube 102 multiplied by the active time.

[0101] 1 , a system 102 for producing a plurality of glass articles from a glass tube may include a converting apparatus 100 having a plurality of processing stations 106, including at least one heating station 202, at least one forming station 204, and a separation station 206. The converting apparatus 100 may be operable to move or pass the glass tube 102 through each of the plurality of processing stations 106. The converting apparatus 100 may include a plurality of holders 130. Each of the plurality of holders 130 may be operable to secure the glass tube 102 and rotate the glass tube 102 about a central axis D of the glass tube 102. It is understood and intended that the converting apparatus 100 may include any of the features, processing stations, or operating parameters described herein for the converting apparatus 100. Each of the plurality of processing stations 106 may have an exposure index defined as the product of the rotational speed (in revolutions per hour) of the glass tube 102 in the holder 130 multiplied by the number of heating elements 301 or forming tools 324 contacting the outer surface 140 of the glass tube 102 in the processing station 106 multiplied by the active time of the glass tube 102 in the processing station 106. One or more of the processing stations 106, such as the heating station 202, the forming station 204, the separation station 206, or a combination thereof, may have an exposure index with an absolute value of 0.30 or less, 0.25 or less, 0.20 or less, 0.10 or less, or 0.05 or less to the nearest integer.

[0102] In any of the systems disclosed herein, the converting device 100 may be an indexing converting device operable to index the glass tube 102 through each of the plurality of processing stations 106. In embodiments, the active time in one or more processing stations 106 may be less than or equal to the dwell time of the converting device 100. In any of the systems disclosed herein, the converting device 100 may be a continuous converting device operable to continuously move the glass tube 102 through the plurality of processing stations 106. In embodiments, the converting device 100 may be operable to vary the rotational speed of the glass tube 102 in the holder 130 to vary the active time of the glass tube 102 in the processing station 106.

[0103] 6A and 6B, in any of the systems disclosed herein, the heating station 202 of at least one conversion apparatus 100 may include at least one swivel burner 330 operably coupled to a swivel burner actuator 332. The swivel burner actuator 332 may be operable to rotate the swivel burner 302 to engage and disengage with the glass tube 102 in the heating station 202, thereby varying the active time of the glass tube 102 engaged with the swivel burner 330. Additionally or alternatively, in embodiments, the systems disclosed herein may include a heating station 202 having a burner movement system 302 operable to move at least one burner horizontally or vertically to engage and disengage with the glass tube 102, thereby varying the active time of the glass tube 102 in the heating station 202. Each heating station 202 of the conversion apparatus 100 may include one, two, three, four, or more than four heating elements 301 , such as burners 302 , swivel burners 330 , etc.

[0104] The heating station 202 is described herein with reference to a burner 302 used to heat the glass tube 102. However, it should be understood that other heating elements may be used to heat the glass tube. The other heating elements may include, but are not limited to, a laser, such as a CO laser, an induction heater, other heating devices, or combinations thereof. The laser heating element may be turned off and on to engage or disengage the heating element with the glass tube 102.

[0105] 9A and 9B , in any of the systems disclosed herein, at least one forming station 204 may include one or more forming tools 324. One or more of the forming tools 324 may be operably coupled to a forming tool actuator 326. The forming tool actuator 326 may be operable to move the forming tools 324 into and out of engagement with the glass tube 102 to vary the active time of the glass tube 102 at the forming station 204. In embodiments, the forming tools 324 may be positioned to contact the outer surface 140 of the glass tube 102. In embodiments, the forming station 204 may include a central forming tool 324c that may be inserted into the interior of the glass tube 102 during its active time at the forming station 204.

[0106] Any of the systems disclosed herein may additionally include a measurement system operable to measure at least the temperature of the glass tube surrounding the glass tube 102, at least a dimension of the glass tube, or a combination thereof. The measurement system may be a thermal imaging system, such as the thermal imaging system disclosed in U.S. Patent Application No. 15 / 928,837, filed March 22, 2018, entitled "SYSTEMS AND METHODS FOR MEASURING THE TEMPERATURE OF GLASS DURING TUBE CONVERSION," the entire contents of which are incorporated herein by reference in their entirety. The thermal imaging system may be operable to measure one or more temperatures surrounding the glass tube. The measurement system may additionally include a dimensional measurement system, such as one or more of a visual imaging system, a laser reflectometer, a laser gauge, an optical micrometer, or other measurement device operable to measure one or more dimensions of the glass tube 102 surrounding the glass tube 102. Other available measurement systems for determining one or more temperatures, dimensions, or both of the glass tube 102 surrounding the glass tube 102 are contemplated. The measurement system may be located at one or more heating stations 202, one or more forming stations 204, a measurement station 218 downstream of a forming station 204, or a combination thereof. In an embodiment, the measurement system may be located at or after the heating station 202, the forming station 204, or both, to directly measure temperature and / or dimensional non-uniformities around the glass tube 102 resulting from the heating station 202 or the forming station 204, respectively.

[0107] 1 , the system for producing a plurality of glass articles from the glass tube 102 may further include a system controller 400 that may be communicatively coupled to the converting apparatus 100. The system controller 400 may include at least one processor 402 and at least one storage medium 404 that includes computer-readable and executable instructions 406. The computer-readable and executable instructions 406, when executed by the processor 402, may cause the system to automatically identify one or more temperature or dimensional non-uniformities of the glass tube 102 around its periphery and determine an exposure index of the glass tube 102 for one or more of the plurality of processing stations 106. As previously discussed, the exposure index of a glass tube 102 at a particular processing station 106 may be equal to the product of the rotational speed (in revolutions per hour) of the glass tube 102 in the holder 130 multiplied by the number of heating elements 301 or forming tools 324 in contact with the outer surface 140 of the glass tube 102 in the processing station 106, multiplied by the active time of the glass tube 102 at the processing station 106. When executed by the processor 402, the computer-readable and executable instructions 406 can cause the system to automatically compare one or more exposure indexes of a processing station 106 to the nearest integer and adjust the rotational speed of the glass tube 102, the active time of the glass tube 102 at the processing station 106, or both, to maintain the absolute value of the difference between the exposure index and the nearest integer at or below 0.30, 0.25, 0.20, 0.10, or even 0.05.

[0108] In an embodiment, the computer-readable and executable instructions 406, when executed by the processor 402, cause the system to automatically receive or obtain the rotation speed of the glass tube 102 from the converting device 100, and multiply the rotation speed of the glass tube 102 by the number of heating elements 301 or the number of forming tools 324 in contact with the outer surface 140 of the glass tube 102, and the active time of the glass tube 102 in the processing station 106 to determine an exposure index for the processing station 106. The system controller 400 can receive the number of forming tools 324 or heating elements 301 in the processing station 106 from the converting device 100 or retrieve this information from at least one storage medium. The system controller 400 can also receive the active time from the converting device 100 or retrieve the active time from at least one storage medium.

[0109] In embodiments, the computer readable and executable instructions 406, when executed by the processor 402, can cause the system to automatically adjust the rotational speed of the glass tube 102 to adjust the exposure index of one or more processing stations 106. Alternatively or additionally, in embodiments, the computer readable and executable instructions 406, when executed by the processor 402, can cause the system to automatically adjust the active time at one or more processing stations 106 to adjust the exposure index. In embodiments, the conversion device 100 can be an index conversion device operable to index the glass tube 102 through each of the plurality of processing stations 106, and the computer readable and executable instructions 406, when executed by the processor 402, can cause the system to automatically increase or decrease the dwell time of the conversion device 100 to increase or decrease the active time of the glass tube 102 at the plurality of processing stations 106.

[0110] In an embodiment, the computer readable and executable instructions 406, when executed by the processor 402, may cause the system to automatically vary the active time at one or more processing stations without changing the dwell time of the conversion apparatus 100. Referring again to Figures 6A and 6B, the system may be operable to vary the active time at the heating station 202 by adjusting the timing of moving the heating element 301 or burner 302 into and out of engagement with the glass tube 102.

[0111] In an embodiment, the conversion apparatus 100 may include at least one heating station 202 having at least one swivel burner 330 operably coupled to a swivel burner actuator 332, where the swivel burner actuator 332 may be operable to swivel the swivel burner 330 into and out of engagement with the glass tube 102. The swivel burner actuator 332 may be communicatively coupled to the system controller 400, such as being in electrical communication with the system controller 400. The swivel burner actuator 332 may be operable to receive a control signal from the system controller 400, where the control signal may cause the swivel burner actuator 332 to swivel the swivel burner 330 into and out of engagement with the glass tube 102. The computer-readable and executable instructions 406, when executed by the processor 402, can cause the system to automatically vary the timing of pivoting the swivel burner 330 to engage and disengage with the glass tube 102 to vary the active time of the glass tube 102 in the heating station 202. The computer-readable and executable instructions 406, when executed by the processor 402, can cause the system to automatically send a control signal to the swivel burner actuator 332 indicating the timing of pivoting the swivel burner 330 to engage and disengage with the glass tube 102. The computer-readable and executable instructions 406, when executed by the processor 402, can cause the system to automatically send a first control signal to the swivel burner 330 or the swivel burner actuator 332 at time T1 to transition the swivel burner 330 into engagement with the glass tube 102. At the end of the activation at time T2, the system controller 400 can send a second control signal to the swivel burner 330 or the swivel burner actuator 332 indicating a command to move the swivel burner 330 out of engagement with the glass tube 102. The system can be operable to vary the duration between T1 and T2 to vary the active time.

[0112] 6A and 6B are shown as including a swivel burner 330 that pivots about axis F to move the flame into and out of engagement with the glass tube 102, it should be understood that other mechanisms for moving the burner 302 into and out of engagement with the glass tube 102 are also contemplated. In embodiments, the heating station 202 may include a translation system (not shown) operable to linearly translate the burner 302 into and out of engagement with the glass tube 102. The translation system may translate the burner 302 laterally (i.e., in the XY plane of FIGS. 6A and 6B) or vertically (i.e., in the ±Z direction of the coordinate axes of FIG. 6A) into and out of engagement with the glass tube 102. The translation system may be communicatively coupled to the system controller 400 and may receive control signals from the system controller 400. The computer readable and executable instructions 406, when executed by the processor 402, can cause the system to automatically send one or more control signals to the burner movement system indicating commands to move the burner 302 into and out of engagement with the glass tube 102. The computer readable and executable instructions 406, when executed by the processor 402, can cause the system to automatically adjust the timing of the control signals to the movement system to vary the active time of the glass tube 102 engaged with the burner 302 in the heating station 202.

[0113] 9A and 9B , in an embodiment, the converting apparatus 100 may include at least one forming station 204 having at least one forming tool 324 operably coupled to a forming tool actuator 326, where the forming tool actuator 326 may be operable to move the forming tool 324 into and out of engagement with the glass tube 102. The forming tool actuators 326 may be communicatively coupled to the system controller 400, such as being in electrical communication with the system controller 400. Each forming tool actuator 326 may be operable to receive a control signal from the system controller 400, where the control signal causes the forming tool actuator 326 to move the forming tool 324 into and out of engagement with the glass tube 102. The computer-readable and executable instructions 406, when executed by the processor 402, may cause the system to automatically vary the timing of moving the forming tool 324 into and out of engagement with the glass tube 102 to vary the active time of the glass tube 102 at the forming station 204. The computer readable and executable instructions 406, when executed by the processor 402, can cause the system to automatically send control signals to the forming tool actuator 326 indicating when to move the forming tool 324 into and out of engagement with the glass tube 102. The computer readable and executable instructions 406, when executed by the processor 402, can cause the system to automatically send a first control signal to the forming tool actuator 326 at time T1, causing the forming tool actuator 326 to move the forming tool 324 into engagement with the glass tube 102. At the end of the activation at time T2, the system controller 400 can send a second control signal to the forming tool actuator 326 indicating a command to move the forming tool 324 out of engagement with the glass tube 102.In an embodiment, at least one forming station 204 may include a plurality of forming tools 324 and a plurality of forming tool actuators 326, each of which is communicatively coupled to the system controller 400 and operable to receive control signals from the system controller 400.

[0114] In embodiments, any of the systems disclosed herein may include a measurement system (not shown), which may be communicatively coupled to the system controller 400. The computer-readable and executable instructions 406, when executed by the processor 402, may cause the system to automatically receive one or more signals or data from the measurement system indicative of one or more characteristics of the glass tube 102. The glass tube characteristics 102 may be one or more temperatures, one or more dimensions, or both, surrounding the glass tube 102. The computer-readable and executable instructions 406, when executed by the processor 402, may cause the system to automatically determine the variability of the temperature, dimensions, or both surrounding the glass tube 102 based on the signals from the measurement system, and adjust the active time at the processing station 106, the rotational speed of the glass tube 102 about the central axis D, or both, to change the exposure index in response to the variability of the temperature, dimensions, or both.

[0115] 1 and 2 , the method disclosed herein for producing a plurality of glass articles from a glass tube 102 may include securing the glass tube 102 in one of a plurality of holders 130 of a converting apparatus 100, where the converting apparatus 100 may include a plurality of processing stations 106. The plurality of processing stations 106 may include at least one heating station 202, at least one forming station 204, at least one separation station 206, or a combination thereof. It is understood and intended that in any of the methods disclosed herein, the converting apparatus 100 may include any of the features, processing stations, or operating parameters described herein for the converting apparatus 100. The method may further include rotating the glass tube 102 about a central axis D of the glass tube 102 within the holder 130, and passing the glass tube 102 through each of the plurality of processing stations 106 to form one or more features on a working end of the glass tube 102. For each processing station 106, the active time of the processing station 106 may be the amount of time that the glass tube 102 maintains engagement with at least one heating element 301 or at least one forming tool 324 while in the processing station 106. The exposure index of each processing station 106 may be equal to the product of the rotational speed (in revolutions per hour) of the glass tube 102 in the holder 130 multiplied by the number of heating elements 301 or the number of forming tools 324 in the processing station 106, and multiplied by the active time of the glass tube 102 in the processing station 106. The method may include operating the conversion device 100 such that the absolute value of the difference between the exposure index and the nearest integer may be 0.30 or less, 0.25 or less, 0.20 or less, 0.10 or less, or even 0.05 or less.

[0116] Any of the methods disclosed herein may further include identifying temperature or dimensional non-uniformities of the glass tube 102 around the glass tube 102, determining an exposure index for the glass tube 102 at one or more of the plurality of processing stations 106, comparing the exposure index to the nearest integer, and adjusting the rotational speed of the glass tube 102, the active time of the glass tube 102 at the processing station 106, or both, to maintain the absolute value of the difference between the exposure index and the nearest integer at or below 0.30, 0.25, 0.20, 0.10, or 0.05. Identifying temperature or dimensional non-uniformities may include measuring at least one temperature, at least one dimension, or both around the glass tube 102, and determining the variability of the temperature or dimension around the glass tube 102 based on the measurements.

[0117] Any of the methods disclosed herein may include maintaining an exposure index within one or more processing stations 106 within ±0.30 of the nearest integer, within ±0.25 of the nearest integer, within ±0.20 of the nearest integer, within ±0.15 of the nearest integer, or within ±0.10 of the nearest integer, where maintaining the exposure index within ±0.30, ±0.25, ±0.20, ±0.15, or ±0.10 of the nearest integer may reduce rotational instability of the glass tube 102, temperature fluctuations around the glass tube 102, dimensional fluctuations around the glass tube 102, or combinations thereof. In an embodiment, the exposure index may be equal to an integer.

[0118] In any of the methods disclosed herein, the conversion apparatus 100 may include a plurality of holders 130, and the methods disclosed herein may include securing one of the plurality of glass tubes 102 to each of the plurality of holders 130, and passing each of the plurality of holders 130 and the glass tubes 102 disposed therein through a plurality of processing stations 106. In embodiments, any of the methods disclosed herein may include determining the active time of each of the plurality of glass tubes 102 in each of the plurality of processing stations 106. Stationarity ofand adjusting the rotational speed of each of the plurality of glass tubes 102 to maintain an absolute value of the difference between the exposure index and the nearest integer for each of the plurality of glass tubes 102 in each of the plurality of processing stations 106 to be 0.30 or less, 0.25 or less, 0.20 or less, 0.10 or less, or 0.05 or less, to reduce temperature and dimensional non-uniformities of the glass tubes 102 around the glass tubes 102.

[0119] Any of the methods disclosed herein may include adjusting the active time of each of the plurality of glass tubes 102 in the processing station 106 to maintain an absolute value of the difference between the exposure index and the nearest integer of 0.30 or less, 0.25 or less, 0.20 or less, 0.10 or less, or 0.05 or less. Adjusting the active time may include increasing or decreasing the dwell time of the conversion device, varying the timing of moving or actuating the heating element 301, the forming tool 324, or both to engage and disengage the glass tubes 102, or a combination thereof.

[0120] 6A and 6B, in any embodiment of the method disclosed herein, one of the processing stations 106 can be a heating station 202 including a swivel burner 330, and the method can include rotating the swivel burner 330 to engage and disengage with the glass tube 102 in the heating station 202. The method can include modifying the active time of the glass tube 102 engaged with the swivel burner 330 by varying the timing of rotating the swivel burner 330 to engage and disengage with the glass tube 102, thereby modifying the exposure index. In an embodiment, the heating station 202 can include a movement system or burner actuator that can linearly move the burner 302 to engage and disengage with the glass tube 102 instead of rotating the burner 302.

[0121] 9A and 9B, in any embodiment of the method disclosed herein, one of the processing stations 106 may be a forming station 204 including one or more forming tools 324 operatively coupled to one or more tool actuators 326, and the method may include actuating the forming tools 324 to engage / contact and disengage / disengage from the glass tube 102 in the forming station 204. The method may include modifying the active time of the glass tube 102 engaging or contacting the forming tool 324 by varying the timing of actuation of the forming tool 324 to engage and disengage from the glass tube 102, thereby modifying the exposure index.

[0122] In any of the methods disclosed herein, each of the multiple processing stations 106 of the converting apparatus 100 may be in a fixed position, and the method may include sequentially and continuously indexing the glass tube 102 through each of the processing stations 106. Alternatively, in embodiments, in any of the methods disclosed herein, the converting apparatus 100 may be a continuous converting apparatus, and the method may include sequentially passing the glass tube 102 through multiple processing stations, where each of the multiple processing stations may move in coordination with the movement of the glass tube 102 during the active time.

[0123] 1 and 2 , a method for producing a plurality of glass articles from a glass tube 102 may include securing the glass tube 102 in one of the holders 130 of a converting apparatus 100, where the converting apparatus 100 includes a plurality of processing stations 106. The processing stations 106 may include at least one heating station 202, at least one forming station 204, and a separation station 206. The method may include rotating the glass tube 102 about a central axis D of the glass tube 102 and passing the glass tube 102 through each of the plurality of processing stations 106 to form one or more features on a working end of the glass tube 102. In any one or more of the plurality of processing stations 106, the active time of the processing station 106 can be the amount of time that the glass tube 102 maintains engagement with the heating element 301 or the forming tool 324 while in the processing station 106, and the rotations per active time ratio is defined as the ratio of the rotations of the glass tube 102 during the active time at each of the plurality of processing stations 106. The absolute value of the difference between the rotations per active time ratio and the nearest integer can be 0.30 or less, 0.25 or less, 0.20 or less, or 0.10 or less. Any of the methods disclosed herein can further include determining the rotations per active time ratio by multiplying the rotation speed (in rotations per hour) of the glass tube 102 about the central axis D of the glass tube holder 130 by the active time.

[0124] Any of the methods disclosed herein may include steps of identifying temperature or dimensional non-uniformities of the glass tube 102 around the glass tube 102, determining the ratio of revolutions per active time of the glass tube 102 at one or more processing stations 106, comparing the ratio of revolutions per active time to the nearest integer, and adjusting the rotation speed, active time, or both of the glass tube 102 to maintain the absolute value of the difference between the ratio of revolutions per active time and the nearest integer to 0.30 or less, 0.25 or less, 0.20 or less, or 0.10 or less. Either method may include maintaining the ratio of revolutions per active time to within ±0.30 of the nearest integer, within ±0.25 of the nearest integer, within ±0.20 of the nearest integer, within ±0.15 of the nearest integer, or within ±0.10 of the nearest integer, and maintaining the exposure index within ±0.30, ±0.25, ±0.20, ±0.15, or ±0.10 of the nearest integer may reduce rotational instabilities of the glass tube 102 and fluctuations in temperature and / or dimensions around the glass tube 102. In an embodiment, the method may include maintaining the ratio of revolutions per active time equal to an integer.

[0125] Any of the methods disclosed herein may include maintaining a constant active time for each of the plurality of glass tubes 102 in each of the plurality of processing stations 106. In embodiments, the active time for each of the processing stations 106 may be maintained constant by maintaining a constant residence time. Any of the methods disclosed herein may include adjusting the rotational speed of each of the plurality of glass tubes 102 to maintain an absolute value of the difference between the ratio of the number of revolutions per active time and the nearest integer for each of the plurality of glass tubes 102 in each of the plurality of processing stations 106 equal to or less than 0.30, 0.25, 0.20, 0.10, or even 0.05 to reduce temperature and dimensional non-uniformities of the glass tubes 102 around the glass tubes 102. In embodiments, the method may include maintaining a constant rotational speed for the glass tubes 102 and increasing or decreasing the active time for the glass tubes 102 in the processing stations 106 to modify the ratio of the number of revolutions per active time. The active time of the glass tube 102 in the processing station 106 can be increased or decreased by varying the amount of time the glass tube 102 is in the processing station 106 (e.g., varying the residence time) or by varying the timing of activating or moving the heating element 301 and / or the forming tool 324 to engage and disengage with the glass tube 102 while in the processing station 106.

[0126] In an embodiment, the converting apparatus 100 may include a plurality of holders 130, and the method may include securing a plurality of glass tubes 102 within the plurality of holders 130, and passing each of the plurality of holders 130 and the plurality of glass tubes 102 through a plurality of processing stations 106. In an embodiment, each of the plurality of processing stations 106 may be in a fixed position, and the converting apparatus 100 may sequentially index the glass tube 102 to each of the plurality of processing stations 106. In an embodiment, the converting apparatus 100 may be a continuous converting apparatus that continuously traverses the glass tube 102 through the processing stations 106, and each of the plurality of processing stations 106 may move with the glass tube 102 during an active time.

[0127] Maintaining the exposure index in the processing stations 106 of the converting apparatus 100 near the nearest integer, such as within 0.30, 0.25, 0.20, 0.15, 0.10, or 0.05, can reduce oscillations around the glass tube 102 during the converting process, reducing temperature and / or dimensional non-uniformity. This reduction in temperature and / or dimensional non-uniformity around the glass tube can reduce or prevent dimensional or cosmetic defects in glass articles produced from the glass tube. Thus, yield from the converting process can be increased by, among other features, reducing yield losses and improving production rates. It should be understood that various aspects of the systems and methods disclosed herein are described in connection with a converting process for producing pharmaceutical vials; however, it should be understood that the systems and methods are applicable to converting processes for producing other articles, such as, but not limited to, cartridges, syringes, ampoules, etc.

[0128] Embodiments of the present disclosure may be embodied in hardware and / or software (including firmware, resident software, microcode, etc.). The conversion apparatus's system controller 400 and / or other controllers on the conversion apparatus 100 may include at least one processor and a computer-readable storage medium (i.e., a memory module), as described herein above. The system controller 400 may be communicatively coupled to one or more system components (e.g., the conversion apparatus 100, the swivel burner actuator 332, the forming tool actuator 326, the movement system, the measurement system, etc.) via wired or wireless communication paths. A computer-usable or computer-readable storage medium or memory module may be any medium that can contain, store, communicate, propagate, or transfer a program for use by or in connection with an instruction execution system, apparatus, or device.

[0129] A computer-usable or computer-readable storage medium or memory module may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a non-exhaustive list) of computer-readable storage media would include: an electrical connection having one or more wires, a portable computer diskette, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, and a portable compact disc read-only memory (CD-ROM). It should be noted that a computer-usable or computer-readable storage medium may be paper or another suitable medium on which a program is printed, since a program can be captured electronically, for example, via optical scanning of paper or other medium, compiled, interpreted, or otherwise processed in an appropriate manner as needed, and stored in computer memory.

[0130] A computer-readable storage medium may include machine-readable and executable instructions for performing operations of the present disclosure. The machine-readable and executable instructions may include computer program code, which may be written in a high-level programming language such as C or C++ for ease of development. In addition, computer program code for performing operations of the present disclosure may also be written in other programming languages, such as, but not limited to, interpreted languages. Some modules or routines may also be written in assembly language or microcode to improve performance and / or memory usage. However, software embodiments of the present disclosure do not depend on implementation in a particular programming language. Furthermore, it will be recognized that any or all functionality of the program modules may also be implemented using discrete hardware components, one or more application-specific integrated circuits (ASICs), or programmed digital signal processors or microcontrollers. [Example]

[0131] The following examples illustrate the operation of the disclosed systems and methods for producing multiple glass articles from glass tubes in a converting apparatus and are not intended to limit the scope of the present disclosure.

[0132] The following examples illustrate the use of the disclosed systems and methods to reduce the dimensional and appearance variations of articles manufactured from glass tubes by reducing the temperature and dimensional non-uniformities surrounding the glass tube. The glass tubes in these examples were aluminosilicate glass tubes, such as VALOR® glass manufactured and sold by Corning Incorporated. Aluminosilicate glass tubes can be further processed after conversion by annealing and / or ion-exchanging the glass tube. While the examples use aluminosilicate glass, the effectiveness of the systems and methods disclosed herein is not dependent on the type or composition of the glass.

[0133] Example 1 - Effect of Exposure Index on Dimensional Uniformity of RP18 In Example 1, experiments were conducted on a converting machine for producing glass vials to demonstrate the effect of the exposure index on the circumferential dimensional non-uniformity of glass tubes. In Example 1, the converting machine was used to convert glass tubes into glass vials. The converting machine used was a vial forming machine model RP18 with an automatic tube feeder manufactured by AMBEG Dr. J. Dichter GmbH, whose main circuit included 18 processing stations. A description of the processing stations in the main circuit of the converting machine used in Example 1 is provided in Table 1 below. A main turret 108 with 18 processing stations, allocated according to Table 1, is shown graphically in FIG. 12.

[0134] [Table 1]

[0135] In Example 1, the exposure index was adjusted by two independent parameters: the rotational speed of the glass tube in the holder and the part rate (related to residence time). A consistent relationship between the shape uniformity around the tube and the exposure index was found, regardless of whether the exposure index was modified by the rotational speed or part rate of the glass tube. In Example 1, the burner was fixed so that the active time for calculating the exposure time was equal to the residence time of the converter. Each of heating stations A7-A9 contained a single flame burner. Therefore, the exposure index in Example 1 was calculated as the product of the rotational speed of the glass tube around its central axis multiplied by the residence time. The rotational speed of the glass tube in Table 2 is provided in revolutions per minute (rpm) and revolutions per second (rps). Table 2 also provides the part rate of the converter for each run condition. The index time was fixed. Therefore, a change in part rate reflects a change in residence time. The residence time used to calculate the exposure index in Table 2 is the residence time corresponding to the part rate listed in Table 2.

[0136] [Table 2]

[0137] For each set of run conditions, the length dimension of the glass tube was measured in the ±Z direction at points around the circumference of the glass tube at the end of the residence time for multiple glass tubes in processing stations A9 and A10. The variability of the length dimension relative to the circumference of the glass tube was determined by taking the difference between the maximum and minimum dimensions. The results of Example 1 are shown graphically in Figure 10. In Figure 10, reference numeral 1002 (black circles) represents data for Runs 1-1 through 1-5, in which the rotation speed of the glass tube was modified and the part rate was held constant, and reference numeral 1004 (plus signs) represents data for Runs 1-6 through 1-10, in which the part rate was varied and the rotation speed was held constant. As shown in Figure 10, varying either the part rate or the rotation speed made no difference to the effect of the exposure index on the length dimension variability.

[0138] Increased variability in the vertical length dimension of the glass tube indicates wobble, resulting in dimensional and cosmetic non-uniformity in the finished glass article. As shown in Figure 10, the variability in the vertical length dimension, and therefore the wobble of the glass tube, is more pronounced at an exposure index of 6.5 compared to exposure indices of 6.0 and 7.0, when measured at the end of the residence time in both the A9 and A10 processing stations. These observations indicate that when the difference between the exposure index and the nearest integer is greater than about 0.30 or about 0.25, the circumferential thermal gradient becomes large, thereby destabilizing the rotating glass preform and resulting in temperature and dimensional non-uniformity in the glass tube during heating and forming. The general trend in variability of the glass tube 102 dimensions (at the end of either A9 or A10 dwell) as a function of exposure index (greater instability at 6.5 revolutions than at 6.0 or 7.0) is observed regardless of whether the exposure index is changed by changing the part rate or by changing the chuck speed (i.e., the rotational speed of the glass tube 102 in the holder 130). This result strongly suggests that the average number of rotations of the glass tube during its active time at the processing station is the source of the instability, as fluctuations are shown to be present by changing two different process variables.

[0139] Example 2 - Effect of Exposure Index on Dimensional Uniformity of RP18 In Example 2, experiments were conducted on a converting machine for producing glass vials to demonstrate the effect of the exposure index on the circumferential dimensional non-uniformity of glass tubes. In Example 2, the converting machine was used to convert glass tubes into glass vials. The converting machine used was a vial forming machine model RP16 with an automatic tube feeder manufactured by AMBEG Dr. J. Dichter GmbH, whose main circuit includes 16 processing stations. A description of the processing stations in the main circuit of the converting machine used in Example 2 is provided below in Table 3.

[0140] [Table 3]

[0141] In Example 2, the exposure index was adjusted by two independent parameters: the rotation speed of the glass tube in the holder and the part rate (related to residence time). A consistent relationship between the shape uniformity around the tube and the exposure index was found, regardless of whether the exposure index was modified by the rotation speed or part rate of the glass tube. In Example 1, the active time for calculating the exposure time was equal to the residence time of the converter. Each of heating stations A7-A9, A11, and A13 contained a single flame burner. Therefore, the exposure index in Example 2 was calculated as the product of the rotation speed of the glass tube around its central axis multiplied by the residence time. The rotation speed of the glass tube in Table 4 is provided in revolutions per minute (rpm) and revolutions per second (rps). Table 4 also provides the part rate of the converter for each run condition. The index time was fixed. Therefore, a change in part rate reflects a change in residence time. The residence time used to calculate the exposure index in Table 4 is the residence time corresponding to the part rate listed in Table 4.

[0142] [Table 4]

[0143] For each set of run conditions in Example 2, vial flange thickness was measured at points around the circumference of the glass tube for multiple glass tubes at the end of their residence time in Processing Station A10. The variability of flange thickness relative to the circumference of the glass tube was determined by taking the difference between the maximum and minimum thicknesses. The results of Example 2 are shown graphically in Figure 11. In Figure 11, reference numeral 1102 (black circles) represents data for Runs 2-1 through 2-5, in which the tube rotation speed was modified and the part rate was held constant, and reference numeral 1104 (plus signs) represents data for Runs 2-6 through 2-10, in which the part rate was varied and the rotation rate was held constant. As shown in Figure 11, varying either the part rate or the rotation rate made no difference to the effect of the exposure index on the linear dimension variability.

[0144] Again, using the RP16 conversion device, it was observed that the exposure index of the glass tube at the processing station had a strong effect on the dimensional uniformity around the glass tube. In particular, Example 2 showed that varying the exposure index reduced the variation in flange thickness when the exposure index was close to an integer value (8 or 9 in Example 2) and significantly increased when the exposure index was greater than 0.25 or 0.3 from the nearest integer (e.g., an exposure index equal to about 8.5 in Examples 2-3 and 2-8).

[0145] As shown in FIG. 11 , the variability in flange thickness, measured at the end of the residence time in the A9 processing station, is more pronounced at an exposure index of 8.5 compared to exposure indices ranging from 8.0 to 8.3 and 8.7 to 9.0 (both within 0.3 of an integer). These observations indicate that when the difference between the exposure index and the nearest integer is greater than about 0.30 or about 0.25, circumferential thermal gradients become large, thereby destabilizing the rotating glass preform and resulting in temperature and dimensional nonuniformity of the glass tube during heating and forming. Therefore, dimensional nonuniformity of features in glass articles produced from the glass tube can be reduced by adjusting operating parameters so that the exposure index of the glass tube is within 0.30 or 0.25 of the nearest integer. This general trend in the variability in flange thickness of the glass tube 102 was observed regardless of whether the exposure index was changed by changing the part rate or the chuck speed (i.e., the rotational speed of the glass tube 102 in the holder 130).

[0146] While various embodiments of the conversion apparatus 100 and systems and methods for producing multiple articles from glass tubes 102 have been described herein, it is understood that each of these embodiments and techniques is intended to be used separately or in combination with one or more other embodiments and techniques.

[0147] It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the present specification cover modifications and variations of the various embodiments described herein, provided that such modifications and variations come within the scope of the appended claims and their equivalents.

[0148] Preferred embodiments of the present invention will be described below in detail.

[0149] Embodiment 1 1. A method for producing a plurality of glass articles from a glass tube, the method comprising: Fixing the glass tube in a holder of a conversion apparatus including a plurality of processing stations, the processing stations including at least one heating station and at least one forming station; rotating the glass tube about a central axis of the glass tube within the holder; and passing the glass tube through each of the plurality of processing stations to form one or more features on a working end of the glass tube, wherein for any of the plurality of processing stations: the active time of the processing station is the amount of time the glass tube remains engaged with at least one heating element or at least one forming tool while in the processing station; the exposure index of the processing station is equal to the product of the rotational speed of the glass tube in the holder multiplied by the number of heating elements or forming tools in the processing station multiplied by the active time of the glass tube in the processing station; and The absolute value of the difference between the exposure index and the nearest integer is 0.30 or less; Step, A method comprising:

[0150] Embodiment 2 identifying temperature or dimensional non-uniformities around the glass tube; determining the exposure index of the glass tube at one or more of the plurality of processing stations; comparing the exposure index to the nearest integer; and adjusting the rotation speed of the glass tube, the active time, or both to maintain the absolute value of the difference between the exposure index and the nearest integer at or below 0.30; 2. The method of embodiment 1, comprising:

[0151] Embodiment 3 2. The method of claim 1, comprising maintaining the exposure index within ±0.30 of the nearest integer, wherein maintaining the exposure index within ±0.30 of the nearest integer reduces rotational instability of the glass tube and fluctuations in temperature around the glass tube.

[0152] Embodiment 4 the active time for each of the plurality of glass tubes at each of the plurality of processing stations. Stationarity of and adjusting the rotational speed of each of the plurality of glass tubes to maintain an absolute value of the difference between the exposure index and the nearest integer for each of the plurality of glass tubes at each of the plurality of processing stations at or below 0.30, thereby reducing temperature and dimensional non-uniformity of the glass tubes around the glass tubes.

[0153] Embodiment 5 2. The method of claim 1, comprising varying the active time of each of the plurality of glass tubes at one or more of the plurality of processing stations to maintain an absolute value of the difference between the exposure index and the nearest integer for each of the plurality of glass tubes at each of the plurality of processing stations at or below 0.30, thereby reducing temperature and dimensional non-uniformity of the glass tube around the glass tube.

[0154] Embodiment 6 1. A system for producing a plurality of glass articles from a glass tube, the system comprising: a converting apparatus having a plurality of processing stations including at least one heating station, at least one forming station, and a separation station; and a plurality of holders, each operable to secure a glass tube and rotate the glass tube about a central axis of the glass tube; Including, the conversion device is operable to move the plurality of holders and glass tubes through the plurality of processing stations; Each of the plurality of processing stations has an exposure index defined as the product of the rotational speed (in revolutions per hour) of the glass tube in the holder multiplied by the number of heating elements or forming tools contacting the outer surface of the glass tube in the processing station multiplied by the active time of the glass tube in the processing station; and an absolute value of the difference between the exposure index and the nearest integer is 0.30 or less for each of the plurality of processing stations; system.

[0155] Embodiment 7 The system of embodiment 6, wherein the at least one heating station of the conversion device includes at least one swivel burner operably connected to a swivel burner actuator operable to rotate the swivel burner to engage and disengage with the glass tube in the at least one heating station, thereby varying the active time of the glass tube in the at least one heating station.

[0156] Embodiment 8 The system of embodiment 6, wherein the at least one heating station of the conversion device includes a burner movement system operable to move at least one burner to engage and disengage horizontally or vertically with the glass tube to vary the active time of the glass tube at the at least one heating station.

[0157] Embodiment 9 The system of embodiment 6, wherein the at least one forming station of the conversion device includes at least one forming tool operably connected to a forming tool actuator operable to move the forming tool to engage and disengage with the glass tube to vary the active time of the glass tube at the at least one forming station.

[0158] Embodiment 10 7. The system of embodiment 6, wherein the conversion device includes a measurement system operable to determine the temperature of at least the glass tube surrounding the glass tube, at least a dimension of the glass tube, or a combination thereof.

[0159] Embodiment 11 The method further includes a system controller communicatively coupled to the conversion device, the system controller having at least one processor and a program that, when executed by the processor, automatically causes the system controller to: Identifying one or more temperature or dimensional non-uniformities around the glass tube; determining an exposure index for the glass tube for one or more of the plurality of processing stations; comparing the exposure index of each of the one or more processing stations to the nearest integer; and adjusting the rotation speed of the glass tube, the active time of the glass tube in the processing station, or both to maintain the absolute value of the difference between the exposure index and the nearest integer at or below 0.30; at least one storage medium containing computer-readable and executable instructions; 7. The system of embodiment 6, comprising:

[0160] Embodiment 12 The system of embodiment 11, wherein the computer-readable and executable instructions, when executed by the processor, cause the system to adjust the rotation speed of the glass tube to adjust the exposure index of one or more of the processing stations.

[0161] Embodiment 13 12. The system of embodiment 11, wherein the computer-readable and executable instructions, when executed by the processor, cause the system to adjust the active time at one or more processing stations to adjust the exposure index.

[0162] Embodiment 14 The system of embodiment 11, wherein the computer-readable and executable instructions, when executed by the processor, cause the system to automatically adjust the active time of the at least one heating station by changing the timing of moving the heating element to engage and disengage with the glass tube.

[0163] Embodiment 15 The system of embodiment 11, wherein the at least one heating station includes a swivel burner operably connected to a swivel burner actuator, the swivel burner actuator is communicatively connected to the system controller and operable to receive control signals from the system controller and rotate the swivel burner to engage and disengage with the glass tube, and the computer-readable and executable instructions, when executed by the processor, cause the system to automatically vary the timing of rotating the swivel burner to engage and disengage with the glass tube to vary the active time of the glass tube at the heating station.

[0164] Embodiment 16 12. The system of claim 11, wherein the at least one forming station includes at least one forming tool operably coupled to a forming tool actuator, the forming tool actuator being communicatively coupled to the system controller and operable to receive one or more control signals from the system controller and move the forming tool to engage and disengage with the glass tube.

[0165] Embodiment 17 The system of embodiment 16, wherein the computer-readable and executable instructions, when executed by the processor, automatically change the timing at which the system moves the forming tool to engage and disengage with the glass tube, thereby changing the active time of the glass tube at the forming station.

[0166] Embodiment 18 The system of embodiment 11, wherein the conversion device includes a measurement system positioned in proximity to the at least one heating station, the at least one forming station, or both, the measurement system being communicatively coupled to the system controller and operable to measure at least one characteristic of the glass tube around the glass tube and to send a signal to the system controller indicative of the characteristic.

[0167] Embodiment 19 19. The system of claim 18, wherein the at least one characteristic of the glass tube includes at least one temperature of the surroundings of the glass tube, at least one dimension, or both.

[0168] Embodiment 20 The system of embodiment 18, wherein the computer-readable and executable instructions, when executed by the processor, cause the system to automatically receive signals from the measurement system indicating one or more characteristics of the glass tube, determine variability in the characteristics of the glass tube around the glass tube, and adjust the active time at the processing station, the rotation speed of the glass tube around the central axis, or both, to change the exposure index in accordance with the variability in the characteristics of the glass tube. [Explanation of symbols]

[0169] 100 Conversion Device 102 Glass tube 103 Glass articles 104 Base 106 Processing Station 108 Main Turret 110 Glass tube loading turret 112 Secondary Processing Station 114 Secondary Turret 116 Main circuit 118 Secondary circuit 130 Holder 132 Loading Channel 142 Shoulder 202 Heating Station 204,204' Forming Station 206 Separation Station 208 Polishing Station 210 Cooling Station 212 Drilling Station 214 Tube Loading Station 216 Discharge Station 218 Measuring Station 220 Pipe Length Drop Station 301 Heating element 302 Burner 304 Fuel supply 306 Oxygen Supply 308 Air Supply 310 Fuel Control Valve 312 Oxygen Control Valve 314 Air Control Valve 324 Molding Tools 326 Forming Tool Actuator 330 Swivel Burner 332 Swivel burner actuator 400 System Controller 402 processor 404 Storage medium 406 Computer-Readable and Executable Instructions

Claims

1. 1. A method for producing a plurality of glass articles from a glass tube, the method comprising: Fixing the glass tube in a holder of a conversion apparatus including a plurality of processing stations, the processing stations including at least one heating station and at least one forming station; rotating the glass tube about a central axis of the glass tube within the holder; and passing the glass tube through each of the plurality of processing stations to form one or more features on a working end of the glass tube, wherein for any of the plurality of processing stations: the active time of the processing station is the amount of time the glass tube remains engaged with at least one heating element or at least one forming tool while in the processing station; The exposure index of the processing station is equal to the product of the rotation speed of the glass tube in the holder multiplied by the number of heating elements or forming tools in the processing station multiplied by the active time of the glass tube in the processing station; and The absolute value of the difference between the exposure index and the nearest integer is 0.30 or less; Step, A method comprising:

2. identifying temperature or dimensional non-uniformities around the glass tube; determining the exposure index of the glass tube at one or more of the plurality of processing stations; comparing the exposure index to the nearest integer; and adjusting the rotation speed of the glass tube, the active time, or both to maintain the absolute value of the difference between the exposure index and the nearest integer at or below 0.30; The method of claim 1 , comprising:

3. 2. The method of claim 1, comprising maintaining the exposure index within ±0.30 of the nearest integer, wherein maintaining the exposure index within ±0.30 of the nearest integer reduces rotational instability of the glass tube and fluctuations in temperature around the glass tube.

4. 2. The method of claim 1, comprising: maintaining constancy of the active time for each of the plurality of glass tubes at each of the plurality of processing stations; and adjusting the rotational speed of each of the plurality of glass tubes to maintain an absolute value of the difference between the exposure index and the nearest integer for each of the plurality of glass tubes at each of the plurality of processing stations at or below 0.30, thereby reducing temperature and dimensional non-uniformity of the glass tube around the glass tube.

5. 2. The method of claim 1, comprising varying the active time of each of a plurality of glass tubes at one or more of the plurality of processing stations to maintain an absolute value of the difference between the exposure index and the nearest integer for each of the plurality of glass tubes at each of the plurality of processing stations at or below 0.30, thereby reducing temperature and dimensional non-uniformity of the glass tube around the glass tube.

6. 1. A system for producing a plurality of glass articles from a glass tube, the system comprising: a converting apparatus having a plurality of processing stations including at least one heating station, at least one forming station, and a separation station; and a plurality of holders, each operable to secure a glass tube and rotate the glass tube about a central axis of the glass tube; Including, the conversion device is operable to move the plurality of holders and glass tubes through the plurality of processing stations; Each of the plurality of processing stations has an exposure index defined as the product of the rotational speed (in revolutions per hour) of the glass tube in the holder multiplied by the number of heating elements or forming tools contacting the outer surface of the glass tube in the processing station multiplied by the active time of the glass tube in the processing station; and an absolute value of the difference between the exposure index and the nearest integer is less than or equal to 0.30 for each of the plurality of processing stations; system.

7. The system of claim 6, wherein the at least one heating station of the conversion device includes at least one swivel burner operably connected to a swivel burner actuator operable to rotate the swivel burner to engage and disengage with the glass tube in the at least one heating station, thereby varying the active time of the glass tube in the at least one heating station.

8. 7. The system of claim 6, wherein the at least one heating station of the conversion device includes a burner movement system operable to move at least one burner to engage and disengage horizontally or vertically with the glass tube to vary the active time of the glass tube at the at least one heating station.

9. 7. The system of claim 6, wherein the at least one forming station of the conversion device includes at least one forming tool operably coupled to a forming tool actuator operable to move the forming tool into and out of engagement with the glass tube to vary the active time of the glass tube at the at least one forming station.

10. The method further includes a system controller communicatively coupled to the conversion device, the system controller having at least one processor and a program that, when executed by the processor, automatically causes the system controller to: Identifying one or more temperature or dimensional non-uniformities around the glass tube; determining an exposure index for the glass tube for one or more of the plurality of processing stations; comparing the exposure index of each of the one or more processing stations to the nearest integer; and adjusting the rotation speed of the glass tube, the active time of the glass tube in the processing station, or both to maintain the absolute value of the difference between the exposure index and the nearest integer at or below 0.30; at least one storage medium containing computer-readable and executable instructions; The system of claim 6 , comprising:

11. 11. The system of claim 10, wherein the computer-readable and executable instructions, when executed by the processor, cause the system to: (1) adjust the rotational speed of the glass tube to adjust the exposure index of one or more of the processing stations; (2) adjust the active time at one or more processing stations to adjust the exposure index; or (3) automatically adjust the active time of at least one heating station by changing the timing of moving the heating element into and out of engagement with the glass tube.

12. The system of claim 10, wherein the at least one heating station includes a swivel burner operably connected to a swivel burner actuator, the swivel burner actuator being communicatively connected to the system controller and operable to receive control signals from the system controller and rotate the swivel burner to engage and disengage with the glass tube, and the computer-readable and executable instructions, when executed by the processor, automatically cause the system to vary the timing of rotating the swivel burner to engage and disengage with the glass tube, thereby varying the active time of the glass tube at the heating station.

13. 11. The system of claim 10, wherein the at least one forming station includes at least one forming tool operably coupled to a forming tool actuator, the forming tool actuator being communicatively coupled to the system controller and operable to receive one or more control signals from the system controller to move the forming tool into engagement and disengagement with the glass tube.

14. The system of claim 13, wherein the computer-readable and executable instructions, when executed by the processor, automatically vary the timing at which the system moves the forming tool to engage and disengage with the glass tube to vary the active time of the glass tube at the forming station.

15. 11. The system of claim 10, wherein the conversion device includes a measurement system positioned proximate to the at least one heating station, the at least one forming station, or both, the measurement system communicatively coupled to the system controller and operable to measure at least one characteristic of the glass tube around the glass tube and send a signal to the system controller indicative of the characteristic.

16. 16. The system of claim 15, wherein the at least one characteristic of the glass tube comprises at least one temperature of the surroundings of the glass tube, at least one dimension, or both.

17. 16. The system of claim 15, wherein the computer-readable and executable instructions, when executed by the processor, cause the system to automatically receive signals from the measurement system indicative of the one or more characteristics of the glass tube, determine variability in the characteristics of the glass tube around the glass tube, and adjust the active time at the processing station, the rotation speed of the glass tube around the central axis, or both, to change the exposure index in response to the variability in the characteristics of the glass tube.

Images