JP5102531B2 - Glass tube cutting method and cutting apparatus - Google Patents

Description

  The present invention relates to a glass tube cutting method and a cutting apparatus for cutting, for example, a fluorescent lamp glass tube into a regular dimension.

  Conventionally, as a method of cutting this type of glass tube, the entire cutting device is moved at the same speed in the same direction as the movement direction of the glass tube by the carriage in synchronization with the drawing speed of the glass tube to be continuously formed, During the movement, a straight cut is made over the entire circumference of the outer peripheral surface of the glass tube by a cutter, and cooling air is blown from the cooling air injection nozzle directly in the vicinity of the cut to quench the cut. A method of cutting a glass tube by generating a crack starting from is known (for example, see Patent Document 1).

  By the way, the glass tube is cooled from the outer surface when it is solidified from the molten state at the time of manufacture, but the temperature decreasing rate of the inner surface is slower than that of the outer surface at a portion where the temperature decreasing rate between the outer surface and the inner surface is large. Therefore, compressive stress is left on the outer surface and tensile stress is left on the inner surface, and the stress difference between the outer surface and the inner surface is large. The conventional example shown in Patent Document 1 uses this stress difference as a starting point for cutting. The glass tube is cut by generating a crack.

However, the stress difference between the outer surface and the inner surface is small, such as the vicinity of the end face of the glass tube, and the stress difference between the outer surface and the inner surface is small. In such a cutting method using the difference in stress between the outer surface and the inner surface, variation in the crack propagation direction caused by the cut is likely to occur, and variation in the surface accuracy and cutting length of the cut surface may occur, resulting in product yield and There was a problem of reducing the quality.
JP-A-9-67136

  The present invention was invented in view of the above-mentioned conventional problems, and can cut the surface accuracy and the cutting length of the cut surface with high accuracy, and improve the product yield and the yield rate. It is an object to provide an apparatus.

In order to solve the above-mentioned problem, the glass tube cutting method according to claim 1 is characterized in that a linear inner peripheral wound 3 is formed on the inner peripheral surface 1a of the hollow glass tube 1 by the cutter 2 over the entire circumference in the circumferential direction A. Is then applied to the outer peripheral portion 1b on the opposite side of the inner peripheral wound 3 by the heating means 4 from the outside of the glass tube 1, and the inner peripheral scratch is applied. The inner peripheral surface of the glass tube is previously cooled by a cooling means (first cooling means 7) in advance .

The glass tube cutting device according to claim 3 is inserted into the inside of the hollow glass tube 1 held by the glass tube feeding device 6 so that the inner peripheral surface 1a of the glass tube 1 has a circumferential direction A all around. A cutter 2 for applying a linear inner circumference scratch 3 and a cooling means (first cooling means 7) for cooling the inner circumference 1a of the glass tube 1 in advance before applying the inner circumference wound 3 And a heating means 4 for locally heating the outer peripheral portion 1b opposite to the inner peripheral wound 3 from the outside of the glass tube 1.

By adopting the cutting method according to claim 1 or the cutting device according to claim 4, that is, the outer peripheral portion 1b opposite to the inner peripheral wound 3 is locally heated to be pulled near the outer peripheral portion 1b. The stress M can be generated, and the vertical crack 5 extending from the inner peripheral scratch 3 to the outer peripheral portion 1b can be easily generated and propagated using the tensile stress M. Therefore, the glass tube 1 can be cut with high accuracy even at a portion where the difference in stress between the outer surface and the inner surface is small, such as near the end surface of the glass tube 1. Further, before the inner peripheral scratch 3 is applied, the inner peripheral surface 1a of the glass tube 1 is cooled in advance by the cooling means 7, so that the compressive stress is locally generated by the contraction caused by the cooling. 3 is applied, and when the portion cooled in advance after applying the inner circumferential wound 3 returns to normal temperature, the portion contracted by cooling expands and returns to the original volume. At this time, a tensile stress m ′ is generated in the vicinity of the inner peripheral wound 3, thereby making it easier to generate and propagate the vertical crack 5.

Further, the glass tube cutting method according to claim 2 is characterized in that after the heating by the heating means 4 is finished, the vicinity of the inner peripheral wound 3 is locally quenched from the inside of the glass tube 1 by the cooling means. As a result, a rapid temperature change is caused in the vicinity of the inner peripheral scratch 3 of the glass tube 1 and stress is concentrated on the site of the inner peripheral scratch 3, whereby the generation and progress of the vertical crack 5 is further facilitated.
The glass tube cutting device according to claim 4 is a cooling means (second cooling means 8) for locally quenching the vicinity of the inner wound 3 from the inside of the glass tube 1 after the heating by the heating means 4 is finished. As a result, the rapid cooling by the second cooling means 8 causes an abrupt temperature fluctuation along the inner flaw 3 so that the vertical crack 5 can be generated and propagated more easily. Be able to.

  Further, the glass tube cutting device according to claim 5 is characterized in that the cutter 2 is constituted by a cemented carbide roller 2A or a diamond cutting tool biased toward the inner peripheral surface 1a of the glass tube 1. Thus, it is possible to easily apply the inner peripheral scratch 3, to prolong the processing life of the cutter 2, and to reduce the processing cost.

  The present invention is not a method of cutting using the stress difference between the outer surface and the inner surface as in the prior art, but generates a tensile stress in the outer peripheral portion by locally heating the outer peripheral portion opposite to the inner peripheral scratch. Using this tensile stress, it is possible to easily generate and propagate a vertical crack extending from the inner peripheral scratch to the outer peripheral portion. Therefore, even in a portion where the stress difference between the outer surface and the inner surface is small, such as near the end surface of the glass tube, the surface accuracy and cutting length of the cut surface can be made high, resulting in an improvement in product yield and yield rate. It is something that can be done.

  Hereinafter, the present invention will be described based on embodiments shown in the accompanying drawings.

  As shown in FIG. 1, the glass tube cutting device of the present invention has a linear shape over the entire circumference A in the inner peripheral surface 1 a of the hollow glass tube 1 held by the glass tube feeding device 6. The main body is composed of the cutter 2 for applying the inner peripheral wound 3 and the heating means 4 for locally heating the outer peripheral portion 1b opposite to the inner peripheral wound 3 from the outside of the glass tube 1. Yes. The glass tube feeding device 6 may be any mechanism that grips the glass tube 1 and rotates the glass tube 1 around its axis, and its structure is not particularly limited.

  The cutter 2 is inserted inside the glass tube 1 to give a straight cut along the inner peripheral surface 1a of the glass tube 1 (hereinafter referred to as “inner peripheral wound 3”). Then, it consists of a cemented carbide roller 2A or a diamond cutting tool biased toward the inner peripheral surface 1a of the glass tube 1. An example of the carbide roller 2A is shown in FIG. The carbide roller 2A includes a horizontal shaft type ring-shaped blade 10, a blade holder 11 that rotatably holds the blade 10, a spring support portion 13 fixed to the roller shaft 12, a spring support portion 13, and a blade holder. 11 and a spring 14 that presses the blade 10 held between the blade holder 11 and the blade 10 toward the inner peripheral surface 1 a of the glass tube 1. The blade 10 of the carbide roller 2A is made of a hard material such as diamond or tungsten oxide. In this example, by rotating the glass tube 1, the blade 10 of the cemented carbide roller 2 </ b> A frictionally slides against the inner peripheral surface 1 a of the glass tube 1 to give the inner peripheral scratch 3. Further, the blade 10 of the cemented carbide roller 2A does not have a function of cutting the glass tube 1, but has only a function of giving an inner peripheral wound 3 which is a cut. In addition, when the thickness of the glass tube 1 is 2 to 3 mm, for example, it is preferable to adjust the pressing force of the blade 10 so that the depth of the inner peripheral wound 3 is 1 mm or less.

  The heating means 4 is for locally heating the outer peripheral portion 1b of the glass tube 1 on the side opposite to the inner peripheral scratch 3, and is constituted by a gas burner 4A in this example. Due to the local heating by the flame of the gas burner 4A, a large tensile stress M is generated in the vicinity of the outer peripheral portion 1b, and the vertical crack 5 starting from the inner peripheral scratch 3 and reaching the outer peripheral portion 1b is easily generated and propagated by this tensile stress M. Is. The vertical crack 5 propagates in a direction B perpendicular to the surface direction of the glass tube 1. The heating means 4 is not limited to the gas burner 4A, and may be, for example, a hot air spray nozzle that blows hot air or an electric heater.

  Next, the cutting process of the glass tube 1 will be described. Here, it is assumed that uniform tensile stress m at the time of manufacture remains on the outer surface and the inner surface of the glass tube 1.

  First, the cemented carbide roller 2A is inserted into the glass tube 1 gripped by the glass tube feeding device 6 from the direction of arrow A in FIG. 1A, and the blade 10 of the cemented carbide roller 2A is at a desired cutting position of the glass tube 1. The position of the blade 10 in the tube axis direction is adjusted so as to come to P, and the blade 10 is moved in the direction indicated by the arrow B in FIG. 1A and pressed against the inner peripheral surface 1a at the cutting position P. The glass tube 1 is rotated around the axis indicated by the arrow c in FIG. Thereby, the linear internal peripheral wound 3 is provided to the internal peripheral surface 1a of the glass tube 1 over the circumferential direction A whole periphery. At this time, as shown in FIG. 2, the inner peripheral surface 1a of the glass tube 1 has a minute undulation, and the blade 10 of the carbide roller 2A follows a constant pressing force by the spring 14 while following this. While being held, the inner peripheral wound 3 is reliably applied by sliding friction.

  Thereafter, the carbide roller 2A is pulled out from the inside of the glass tube 1, and the outer peripheral portion 1b opposite to the inner peripheral wound 3 is locally heated by the gas burner 4A from the outside of the glass tube 1 as shown in FIG. This causes a sudden temperature fluctuation in the vicinity of the inner peripheral wound 3, and at the same time, a tensile stress M (> m) larger than the residual tensile stress m is generated in the outer peripheral portion 1b, so that stress is applied to the site of the inner peripheral wound 3. As a result, the vertical cracks 5 are generated and propagated.

  Therefore, instead of the conventional method of cutting using the stress difference between the outer surface and the inner surface, in the present invention, the outer peripheral portion 1b opposite to the inner peripheral wound 3 is locally heated as described above. A tensile stress M is generated in the outer peripheral portion 1b, and the vertical crack 3 reaching the outer peripheral portion 1b from the inner peripheral scratch 3 can be easily generated and propagated by using the tensile stress M. Therefore, even in a portion where the stress difference between the outer surface and the inner surface is small, such as near the end surface of the glass tube 1, it is possible to obtain the effect that the surface accuracy and the cutting length of the cut surface can be made high, and the product yield and the non-defective product. The rate can be improved.

  In this example, the carbide roller 2A constituting the cutter 2 can be made to have a simple structure in which the blade 10 is pressed against the inner peripheral surface 1a of the rotating glass tube 1 by a spring 14, and the inner peripheral surface of the glass tube 1 is also provided. There is also an advantage that the inner peripheral wound 3 can be easily and reliably applied by the blade 10 of the super hard roller 2A while following the minute undulation of 1a.

  In this example, the cutter 2 and the gas burner 4A are fixed, and the glass tube 1 is rotated. However, for example, the glass tube 1 is fixed and can move along the outer peripheral surface of the glass tube 1. It is also possible to use a rotary cutter or a rotary burner.

  3 and 4 are explanatory diagrams of another embodiment of the present invention. In this example, from the inner side of the glass tube 1 after the heating by the first cooling means 7 for cooling the inner peripheral surface 1a in advance from the inner side of the glass tube 1 and the heating means 4 before the inner peripheral wound 3 is applied. The case where the 2nd cooling means 8 for quenching locally the inner periphery wound 3 vicinity is shown is shown. In addition, each point of the structure of the cutter 2 and the gas burner 4A, and the point of cutting a portion where the stress difference between the outer surface and the inner surface is small, such as the vicinity of the end surface of the glass tube 1, is the same as the embodiment of FIG. Parts corresponding to those in the embodiment of FIG. Note that the present invention is not limited to the case where both the pre-cooling process by the first cooling means 7 and the post-cooling process by the second cooling means 8 are provided, and either one of the cooling processes can be omitted. In this example, both the cooling steps by the first and second cooling means 7 and 8 are provided, and the cooling air is blown toward the inner peripheral surface 1a of the rotating glass tube 1 as each cooling means 7 and 8. Blower nozzles 7A and 8A are exemplified.

  First, as shown in FIG. 3 (a), the blower nozzle 7A is inserted into the glass tube 1 gripped by the glass tube feeding device 6 and the glass tube 1 is rotated to give the inner peripheral surface 3 of the glass tube 1. The portion is preliminarily locally cooled by jetting cold air from the blower nozzle 7A.

  After that, the blower nozzle 7A is pulled out from the inside of the glass tube 1, and an applying process of the inner peripheral scratch 3 by the cutter 2 shown in FIG. 3 (b), and the outer peripheral portion 1b opposite to the inner peripheral scratch 3 shown in FIG. 3 (c). And a heating step of locally heating the gas with a gas burner 4A. The application process and heating process of these inner circumference wounds 3 are the same as those shown in FIGS. After that, after the heating of the gas burner 4A is stopped, the blower nozzle 8A is inserted into the glass tube 1 and the glass tube 1 is rotated as shown in FIG. For example, air at 20 ° C. is injected.

  Thus, in this example, by compressing the inner peripheral surface 1a in advance before the inner peripheral wound 3 is applied, the compressive stress n is locally applied by contraction in the cooling region e as shown in FIG. When the inner peripheral wound 3 is applied in the generated state, and the portion cooled after the inner peripheral wound 3 is applied returns to room temperature, the contracted portion expands to the original volume by cooling. Return. At this time, as shown in FIG. 4B, a tensile stress m ′ is generated in the vicinity of the inner peripheral wound 3, and then the outer surface side is heated by the gas burner 4A in FIGS. 3C and 4C. Combined with the generation of a large tensile stress M, the generation and progress of the vertical crack 5 is further facilitated.

  Furthermore, in this example, after the heating of the gas burner 4A is stopped, the vicinity of the inner peripheral wound 3 is rapidly cooled as shown in FIG. The stress is concentrated on the portion 3. That is, a compressive stress is generated in the vicinity of the inner peripheral wound 3, and a large tensile stress M is generated by heating in the outer peripheral portion 1b away from the inner peripheral wound 3, so that the vertical crack 5 starting from the inner peripheral wound 3 is generated. Progress is further facilitated, and as a result, the glass tube 1 can be cut more accurately.

1 shows an embodiment of the present invention, (a) is an explanatory view of a glass tube cutting device, (b) is a cross-sectional view of a glass tube having an inner circumference scratched by the cutter, (c) These are sectional drawings explaining the state which heats the outer peripheral part on the opposite side to an internal peripheral crack same as the above by a heating means. It is an axis perpendicular sectional view of a glass tube at the time of giving an inner circumference crack with a cutter same as the above. The other embodiment of this invention is shown, (a) is process explanatory drawing which cools the internal peripheral surface of a glass tube beforehand, before giving an internal peripheral wound, (b) is an internal peripheral wound with a cutter same as the above. It is process explanatory drawing to provide, (c) is process explanatory drawing which heats the outer peripheral part on the opposite side to an internal peripheral crack same as the above with a heating means, (d) is from the inner side of a glass tube after completion | finish of a heating. It is process explanatory drawing for quenching locally the inner periphery wound vicinity locally. (A) is explanatory drawing of the compressive stress which generate | occur | produces in an inner periphery flaw when giving an internal peripheral wound with the cutter shown in FIG.3 (b), (b) is an internal after giving an internal peripheral wound same as the above. It is explanatory drawing of the tensile stress which generate | occur | produces in the circumference | surroundings wound, (c) is explanatory drawing of the tensile stress which generate | occur | produces in an outer peripheral part by the heating by the gas burner shown in FIG.3 (c).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass tube 1a Inner peripheral surface 1b Outer peripheral part 2 Cutter 2A Carbide roller 3 Inner peripheral wound 4 Heating means 5 Vertical crack 6 Glass tube feeder 7 First cooling means 8 Second cooling means A Circumferential direction

Claims (5)

The inner peripheral surface of the hollow glass tube is given a linear inner peripheral scratch over the entire circumference in the circumferential direction by a cutter, and then the outer peripheral portion on the opposite side to the inner peripheral scratch is heated by heating means from the outside of the glass tube. A method for cutting a glass tube , which is locally heated, wherein the inner peripheral surface of the glass tube is cooled in advance by a cooling means before the inner peripheral scratch is applied . 2. The method for cutting a glass tube according to claim 1, wherein after the heating by the heating means is completed, the vicinity of the inner peripheral flaw is locally quenched from the inside of the glass tube by the cooling means. A cutter that is inserted into the inside of a hollow glass tube gripped by a glass tube feeding device and gives a linear inner circumference scar to the inner circumferential surface of the glass tube over the entire circumference in the circumferential direction; Cooling means for pre-cooling the inner peripheral surface of the glass tube before applying the peripheral scratch, and heating means for locally heating the outer peripheral portion opposite to the inner peripheral scratch from the outside of the glass tube A glass tube cutting device characterized by comprising: 4. The glass tube cutting device according to claim 3, further comprising a cooling means for locally quenching the vicinity of the inner peripheral wound from the inside of the glass tube after the heating by the heating means is finished. The cutter, the cutting equipment of the glass tube according to claim 3 or 4 further characterized in that toward the inner circumferential surface of the glass tube is composed of a cemented carbide roller or diamond tool is spring biased.

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