Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B21/00—Severing glass sheets, tubes or rods while still plastic
  • C03B21/02—Severing glass sheets, tubes or rods while still plastic by cutting

Definitions

• the present invention relates to a method for separating a glass strand during the drawing process, in that the glass strand is conveyed in the direction of its longitudinal axis and thereby creates a predetermined breaking point on the outer jacket and the glass strand is then separated by a force acting in the area of the predetermined breaking point.
• the invention further relates to a device for separating a
• Glass strand during the drawing process with a pulling device for conveying the glass strand in the direction of its longitudinal axis and with a separating tool for separating the glass strand in the region of a predetermined breaking point generated on the outer jacket of the glass strand during the drawing process.
• a predetermined breaking point is initially created on the outer casing of the glass strand moving in the direction of its longitudinal axis due to an injury to the outer casing surface, for example by a scratch, a crack, a cut or the targeted introduction of a tension ring, on which the glass strand is subsequently broken.
• a circumferential crack is made using a cutting tool in the form of a diamond file, a diamond cutter or a hard metal cutting edge.
• laser cutters are known in which the glass strand is injured by a laser spot, and then water is sprayed from a traveling nozzle, which leads to the glass strand breaking in the area of the surface injury.
• DE-C 199 08 342. described a method in which a screw is used to cut a glass strand rotating about its longitudinal axis, which screw coaxially to the glass strand and arranged at a small distance from it rotates about its screw shaft.
• the peripheral edge of the screw spiral is designed as a cutting edge and extends only over part of the screw shaft circumference, so that the rotating screw with its cutting edge grasps the outer casing of the glass strand at a specific point of engagement. If the helical shape and the movement of the glass strand are appropriately coordinated, it can be achieved that the point of engagement migrates around the glass strand in a plane perpendicular to the axis, so that an axially perpendicular, circumferential incision line is produced at which the glass strand is separated.
• the glass strand is usually separated by a force that impulses the area of the predetermined breaking point, such as a hammer blow. This can result in numerous pieces of glass and tears in the glass strand. High cutting allowances are therefore required, which lead to correspondingly high material losses.
• the known method is particularly unsuitable for separating glass rods with a large outside diameter or thick-walled glass tubes.
• the present invention is based on the object of specifying a method for separating glass strands during the drawing process, by means of which high-quality cut surfaces can be obtained and cutting losses can be reduced.
• the invention has for its object to provide a simple and reliable device for separating glass strands during the drawing process, which is particularly suitable for performing the method according to the invention.
• this object is achieved, based on the method mentioned at the outset, in that a bending device is fixed to the outer jacket during the pulling process and by means of this a bending moment is induced in the area of the predetermined breaking point, which is continuously increased until the glass strand is broken.
• a bending device is fixed to the glass strand so that it is conveyed at the speed of the moving glass strand in the direction of its longitudinal axis.
• a bending moment is induced in the area of the predetermined breaking point by means of the bending device by generating compressive or tensile forces acting perpendicular to the longitudinal axis of the glass strand, which ultimately lead to breakage of the glass strand.
• the bending moment is continuously increased until the glass strand breaks.
• the continuous, gradual increase in the bending moment enables a metered introduction of force in the area of the predetermined breaking point, so that only that force acts on the glass strand that is necessary for breaking. This largely prevents uncontrolled crack propagation into the glass strand, the quality of the cut surfaces is increased and cutting losses are reduced.
• the application of the bending moment and its increase until the glass strand breaks requires a certain period of time, while the glass strand and bending device are locally fixed to one another, so that the forces can act on the area of the predetermined breaking point. This period of time is ensured in the method according to the invention in that the bending device is attached to the moving glass strand.
• the predetermined breaking point is formed as an almost punctiform surface damage to the outer casing or it extends radially as a linear surface damage over at least part of the outer casing.
• the pneumatic or hydraulic drive enables simple design of the pressure hull.
• a pneumatic or hydraulic drive facilitates the connection of several pressure elements, so that several bending devices can be operated with a corresponding drive.
• the bending moment is applied by advancing a pressure element connected to the bending device perpendicular to the longitudinal axis of the glass strand.
• the feed of the pressure body takes place continuously, preferably regulated or controlled. Due to its fixation on the outer casing, the pressure body moves at the same speed as the glass strand, so that a coordination of the withdrawal speed and the axial movement of the pressure body is not necessary.
• the bending device advantageously comprises support elements axially spaced apart and on both sides of the predetermined breaking point, against which the glass strand rests, the pressure element being pushed in the radial direction against the glass strand resting on the support elements.
• two or more support elements are provided on both sides of the predetermined breaking point, as seen in the axial direction.
• an opposing pressure force is generated on the outer jacket from the side opposite the support elements, which force is continuously increased.
• This is done according to the invention by a continuous feed of the pressure body against the outer jacket, the feed either by tensile forces pulling on the pressure element from the side of the support elements or by pressure forces acting on the pressure body from the side opposite the support elements. It has proven to be particularly suitable to apply the bending moment by means of a pressure body acting selectively on the outer jacket. The selective application of force creates a high surface pressure with little damage in the area of the outer jacket.
• the bending moment is applied by means of a pressure body that acts flat on the outer jacket. Due to the two-dimensional introduction of pressure, high local forces and the associated damage to the outer jacket are avoided.
• the above-mentioned object is achieved according to the invention starting from the device of the type mentioned at the outset in that the separating tool comprises a frame structure at least partially encompassing the outer casing, on which a bending device with a pressure body movable in the direction perpendicular to the longitudinal axis is held, the Movement of the pressure body in the direction of the predetermined breaking point takes place by means of an adjustable or controllable drive connected to the pressure body via a flexible line.
• a bending device which is to be fastened to the glass strand during the drawing process and which comprises a pressure body which generates a bending moment in the region of a predetermined breaking point.
• Bending device is held on a frame structure, which is fixed to the glass strand during the drawing process by completely or partially encompassing the outer jacket. This ensures a local fixation of the moving glass strand and the bending device to one another.
• the pressure body serves to apply a bending moment to the glass strand in the direction of a predetermined breaking point in a direction perpendicular to the longitudinal axis.
• the bending moment is applied by applying a force acting on the pressure body and directed against the outer jacket in the direction perpendicular to the longitudinal axis. This can be a tensile force or a compressive force. It is essential that the pressure body can be moved continuously against the outer casing (in the following this movement is also referred to as "feed").
• the pressure body is connected directly or indirectly - via the drive - to a regulating or control unit.
• the feed of the pressure body against the outer jacket can be regulated or controlled, the flexible Line allows the movement of the pressure body in the direction of the glass strand longitudinal axis.
• the continuous, gradual increase in the bending moment enables a metered introduction of force in the area of the predetermined breaking point, so that only that force acts on the glass strand that is necessary for breaking. This largely prevents uncontrolled crack propagation into the glass strand, the quality of the cut surfaces is increased and cutting losses are reduced.
• the bending device fixed to the glass strand is conveyed at the speed of the moving glass strand in the direction of its longitudinal axis, a bending moment being induced in the region of the predetermined breaking point at the same time by means of the bending device, which ultimately leads to breakage of the glass strand.
• the device according to the invention is therefore particularly suitable in particular for carrying out the method according to the invention.
• a frame structure on which a tool for producing a mechanical weakening of the glass strand has proven to be particularly favorable is attached in the area of the predetermined breaking point.
• the tool is, for example, a glass scribing tool or a laser. Since a single device fixed to the glass strand and moving with it (the bending device) both causes the weakening of the glass strand (for example by scoring or by generating thermal stresses) and the bending moment in the area of the predetermined breaking point, the exact positioning of the Pressure body in the area of mechanical weakening facilitated.
• the bending device preferably comprises a pneumatic or a hydraulic drive, by means of which the pressure body can be moved against the outer jacket.
• a pneumatic or hydraulic drive results in a simple structural design of the pressure body, for example in the form of a pressure cylinder.
• a pneumatic or hydraulic drive facilitates the connection of several pressure hulls for one or more drawing systems.
• the pressure body is fed continuously, regulated or controlled by means of the regulating or control device.
• the bending device advantageously comprises axially spaced and on both sides of the predetermined breaking point arranged support elements on which the glass strand rests against the advance of the pressure body.
• the pressure element can be displaced in the radial direction against the glass strand resting on the support elements.
• two or more support elements - seen in the axial direction - are provided on both sides of the predetermined breaking point.
• a compressive force acting against the support elements is generated on the side opposite the outer jacket, which is continuously increased.
• the thrust of the pressure body against the outer jacket is effected either by tensile forces or by compressive forces.
• An embodiment of the device according to the invention is preferred in which the pressure body has a tip acting on the outer jacket.
• a punctual results Force transmission in a narrowly limited area, so that there is little damage to the outer casing by the pressure body.
• the device according to the invention has a pressure body on which an edge acting on the outer jacket has.
• the bending device is provided on the side of the glass strand opposite the pressure body with an impact surface made of a deformable material.
• Glass strand in the area of the predetermined breaking point causes the bending forces acting on the glass strand in the radial direction to cause the severed section to tilt axially.
• an impact surface is provided in the area of the predetermined breaking point, against which the front end of the severed section strikes when it is tilted.
• the impact surface is covered with a deformable, soft material, so that damage to the separated section is avoided.
• a further improvement results from the fact that an automatic positioning device is provided for fixing the frame structure to the glass strand in a predetermined position.
• the automatic positioning device is, for example, a mechanical robot.
• the section separated from the glass strand is collected or held and fed to a further processing step.
• a gripping tool engaging below the predetermined breaking point on the outer jacket is particularly suitable for holding the section separated from the glass strand.
• FIG. 2 shows another embodiment of the device according to the invention.
• FIG. 1 shows a quartz glass tube 1 with a vertically oriented longitudinal axis 2, which is drawn off in the direction of arrow 3 by means of a pulling device from a hollow cylinder that has been partially softened in an oven. Suitable pulling devices and ovens are generally known and are therefore not shown in FIGS. 1 and 2.
• the quartz glass tube 1 has an outer jacket 4, which is provided with a radial circumferential crack in the area of a predetermined breaking point 5.
• a bending device is attached to the quartz glass tube 1, to which reference number 6 is assigned.
• the bending device 6 comprises an elongated, rigid frame 7 on which a pressure cylinder 8 with a chisel-shaped tip is held, which can be advanced and moved in a controlled manner in the direction perpendicular to the longitudinal axis 2 by means of a hydraulic drive 9 against the outer jacket 4 of the quartz glass tube 1.
• the pressure cylinder 8 is connected to the hydraulic drive 9 via a flexible hose 10 and this is connected to a control unit 12 via an electrical connecting line 13.
• the pressure cylinder 8 is moved back and forth in the direction perpendicular to the longitudinal axis 2.
• the pressure cylinder 8 Opposite the pressure cylinder 8, two support elements 14, which are spaced apart in the direction of the longitudinal axis, are fastened to the frame 7, against which the quartz glass tube 1 rests such that the predetermined breaking point 5 lies centrally between the support elements 14.
• the distance between the bearing elements 14 is 800 mm.
• the frame 7 has a wall 15 running parallel to the longitudinal axis 2, in which a layer 16 of graphite felt is embedded opposite the pressure cylinder 8.
• the frame 7 is releasably attached to the quartz glass tube 1 by means of clamps 17 which encompass the outer jacket 4. These are designed so that they do not damage the outer jacket 4.
• a quartz glass tube 1 with an outer diameter of 60 mm and a wall thickness of 20 mm is pulled off in the direction of arrow 3 at a pull-off speed of 145 mm / min.
• the quartz glass tube 1 is created in the area of a predetermined breaking point 5 with a diamond cutter, and the frame 7 is then attached to the quartz glass tube 1 in such a way that the pressure cylinder 8 comes to lie exactly at the level of the predetermined breaking point 5.
• the pressure cylinder 8 By means of the hydraulic drive 9 - regulated by the control unit 12 - the pressure cylinder 8 is advanced against the outer jacket 4, the long edge of the chisel-shaped tip being perpendicular to the longitudinal axis 2. Due to the support of the quartz glass tube 1 supported on the support elements 14, a bending stress is induced by the advance of the pressure cylinder 8 in the area of the predetermined breaking point 5.
• the feed of the printing cylinder 8 is 30 mm / s.
• the bending stress in the area of the predetermined breaking point 5 is continuously increased, so that after about four seconds the quartz glass tube 1 breaks in the area of the predetermined breaking point 5.
• the continuous, gradual increase in the bending stress enables a metered introduction of force in the area of the predetermined breaking point 5, so that only that force is exerted on the quartz glass tube 1 acts, which is necessary for breaking. This prevents uncontrolled crack propagation into the quartz glass tube 1, the quality of the cut surfaces is increased and cutting losses are reduced
• the severed section 18 tilts with respect to the longitudinal axis 2 and strikes with its upper end against the graphite felt layer 16. This prevents damage to the tube end.
• the separated section 18 is collected in a container (not shown in FIG. 1) and fed to a subsequent processing step.
• FIG. 2 If the same reference numerals are used in FIG. 2 as in FIG. 1, then the same or equivalent parts of the device are designated as in FIG. 1. Reference is made to the above explanations for FIG. 1.
• FIG. 2 shows a quartz glass rod 21 with a vertically oriented longitudinal axis 2, which is pulled off in the direction of arrow 3 by means of a pulling device from a hollow cylinder which has been partially softened in an oven.
• the quartz glass rod 21 has an outer jacket 4, which is provided with a crack in the area of a predetermined breaking point 5.
• a bending device is attached to the quartz glass rod 21 and is assigned the reference number 22 overall.
• the bending device 22 comprises an elongate rigid frame 23 on which a pressure cylinder 24 provided with a tip 25 is held.
• the pressure cylinder 24 can be pushed back and forth in a controlled manner in the direction perpendicular to the longitudinal axis 2 by means of a hydraulic drive 9 against the outer jacket 4 of the quartz glass rod 21.
• the pressure cylinder 24 is connected to the hydraulic drive 9 via a flexible hose 10 and this is connected to a control unit 12 via an electrical connecting line 13.
• the pressure cylinder 24 is moved back and forth in the direction perpendicular to the longitudinal axis 2.
• a bracket 27 rotatably mounted about the longitudinal axis 2 is held on the frame 23, to which a glass scribing tool 28 is fastened with a hard metal cutting edge, by means of which the bracket 27 is scored by rotating the bracket 27 around a pitch circle in the area of the predetermined breaking point 5.
• the frame 23 is detachably fastened to the quartz glass rod 21 by means of clamps 17 which surround the outer jacket 4.
• the clamps 17 are arranged on both sides of the pressure cylinder 24 in such a way that the predetermined breaking point 5 lies centrally between them.
• the distance between the clamps 17 is 800 mm.
• the clamps 17 are designed in such a way that damage to the outer jacket 4 is avoided even under high pressure loads.
• a holding device 29 is provided for the section 26 to be separated.
• the holding device 29 has a bracket, which surrounds the quartz glass rod 21 below the frame 23.
• a quartz glass rod 21 with a diameter of 50 mm is pulled off in the direction of arrow 3 at a pull-off speed of 180 mm / min.
• the bending device 22 is controlled by an automatic machine and is attached to the outer jacket 4 in the area of the predetermined breaking point 5, the tip 25 of the pressure cylinder 24 coming to lie exactly at the level of the predetermined breaking point 5.
• the glass scribing tool 28, which rests on the outer casing 4 with pressure, is then rotated by pivoting the bracket 27 by 180 degrees about the longitudinal axis 2, so that a tear extending around half the outer circumference 4 is produced exactly in the area of the predetermined breaking point and opposite the tip 25 of the printing cylinder 24 becomes.
• the feed of the printing cylinder 8 is 25 mm / s.
• the bending stress in the area of the predetermined breaking point 5 is continuously increased, so that the fracture of the quartz glass rod 21 is brought about in the area of the predetermined breaking point 5 after about five seconds.
• the separated section 26 is held on the holding device 29 and automatically fed to further processing by means of this.
• the continuous, gradual increase in the bending stress enables a metered introduction of force in the area of the predetermined breaking point 5, so that only that force acts on the quartz glass rod 21 that is required for breaking. This prevents uncontrolled crack propagation into the quartz glass rod 1, the quality of the cut surfaces is increased and cutting losses are reduced.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)
• Manufacture, Treatment Of Glass Fibers (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7700511

Family Applications (1)

Country Status (5)

Citations (5)

Family Cites Families (1)

• 2001
  • 2001-09-27 DE DE10147705A patent/DE10147705B4/de not_active Expired - Fee Related
• 2002
  • 2002-09-20 TW TW091121654A patent/TW570899B/zh not_active IP Right Cessation
  • 2002-09-23 KR KR10-2004-7003598A patent/KR20040034731A/ko not_active Application Discontinuation
  • 2002-09-23 JP JP2003532414A patent/JP2005520760A/ja active Pending
  • 2002-09-23 WO PCT/EP2002/010642 patent/WO2003029155A1/de active Application Filing

Patent Citations (5)

Non-Patent Citations (3)

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