JP7028081B2 - Glass tube manufacturing method and glass tube end face processing equipment - Google Patents

Description

The present invention relates to a glass tube manufacturing method used when processing an end face of a glass tube, and a glass tube end face processing device .

Conventionally, a method for manufacturing a glass tube in which the end face of the glass tube is rounded by a treatment (glazing treatment) of heating and softening the end face of the glass tube with a laser or the like is well known (see Patent Document 1 and the like). This is because if there are corners or minute cracks on the end face of the glass tube, the end of the glass tube may be chipped or cracked during transportation or the like.

Japanese Unexamined Patent Publication No. 2000-344551

By the way, in this kind of glazing processing, the end face of the glass tube is rapidly heated and rapidly cooled only by the laser processing of this heating. Therefore, there is a problem that a large residual stress remains in the glass tube after processing and the risk of breakage is high.

An object of the present invention is to provide a glass tube manufacturing method capable of reducing residual stress of a glass tube in glazing processing, and a glass tube end face processing apparatus .

The method for manufacturing a glass tube that solves the above problems is a method of glazing the end face of the glass tube, that is, a preheating step of preheating the end face of the glass tube with a preheating source, and an end face of the glass tube after the preheating step. Was provided with a main heating step of main heating by the main heating source.

According to this configuration, in the glazing process of the end face of the glass tube, the end face of the glass tube is first preheated, and then the end face of the glass tube is mainly heated. Therefore, it is possible to heat the end face of the glass tube to some extent before the main heating, so that the temperature required for the main heating can be kept low. As a result, the temperature gradient of cooling after processing becomes gentle, so that the residual stress generated in the glass tube can be suppressed to a low level. Therefore, it is possible to reduce the risk of breaking the glass tube.

In the glass tube manufacturing method, the preheating source is a laser type and the end face of the glass tube is preheated by irradiating a beam having a Gaussian distribution, and the main heating source is a laser type and a line beam. It is preferable to main-heat the end face of the glass tube by irradiating the glass tube. According to this configuration, the preheating range of the preheating source can be widened, so that the end face of the glass tube can be preheated more reliably. Further, during the main heating, the end face of the glass tube can be heated with the required high temperature heat.

In the glass tube manufacturing method, it is preferable to preheat a plurality of the glass tubes at the same time in the preheating step. According to this configuration, it is possible to efficiently preheat the glass tube.

In the glass tube manufacturing method, it is preferable to transport a plurality of the glass tubes arranged in a line in the transport direction, and to perform the preheating and the main heating in the transporting process. According to this configuration, since the preheating and the main heating are performed on the glass tube while being conveyed at a predetermined speed, the preheating and the main heating can be efficiently performed.

In the glass tube manufacturing method, in the preheating step, it is preferable to arrange the preheating source diagonally with respect to the transport direction of the glass tube and heat the end face of the glass tube diagonally to execute the preheating. .. According to this configuration, when the light of one light source is branched to reach a plurality of preheat sources and the laser is irradiated from these preheat sources, the preheat sources are arranged diagonally so that one light source and a plurality of preheat sources can be obtained. It is possible to set the optimum orientation with the preheat source. In this way, the light source can be shared among the plurality of preheat sources, which is advantageous in reducing the equipment cost.

In the glass tube manufacturing method, it is preferable that the preheating source and the main heating source are arranged so that the irradiation ranges of the heat rays irradiated by each overlap each other. According to this configuration, the end face of the glass tube can be smoothly transferred from the preheating to the main heating, which is advantageous for optimally glazing the end face of the glass tube.

In the glass tube manufacturing method, it is preferable that the preheating step and the main heating step are sequentially performed on each of the one end face of the glass tube and the other end face of the glass tube. According to this configuration, both end faces of the glass tube can be glazing.

In the glass tube manufacturing method, it is preferable to perform preheating by irradiating a laser having an output wattage of 20 to 30 W for 0.5 to 1 second in the preheating step. According to this configuration, it is possible to optimize the output wattage and the preheating time of the preheating laser.

In the main heating step carried out by the line beam of the laser in the glass tube manufacturing method, the beam width of the line beam is T, and the inclination angle of the beam trajectory with respect to the transport direction A of the glass tube is θ. When the outer diameter is R, it is preferable to carry out the main heating so as to satisfy the relationship represented by the following equation (1): T × sin θ ≧ R. According to this configuration, it is possible to carry out the main heating under the optimum conditions.

The glass tube end face processing apparatus for solving the above problems has a configuration in which the end face of the glass tube is glazing, and the preheating source for preheating the end face of the glass tube and the end face of the glass tube after preheating are mainly heated. Equipped with this heating source.

The glass tube that solves the above problems has a structure in which the end face is made of a glaze surface, and the residual stress is maximum at a position of 0.5 to 1 mm in the axial direction from the end face, and the maximum value of the residual stress is 2 to 2. It is 7 MPa.

According to the present invention, the residual stress of the glass tube can be reduced in the glazing process.

The block diagram of the glass tube end face processing apparatus of one Embodiment. Front view of the glass tube end face processing device. (A) to (d) are process diagrams of glazing processing of the end face of the glass tube. Temperature gradient diagram during glazing in each case with and without preheating. The schematic diagram which shows the position of occurrence of the residual stress without preheating. Schematic diagram showing the position where residual stress is generated when there is preheating.

Hereinafter, an embodiment of a glass tube manufacturing method, a glass tube end face processing apparatus, and a glass tube will be described with reference to FIGS. 1 to 6.
As shown in FIGS. 1 and 2, the glass tube end face processing device 1 glazing (mouth-burns) the end face 3 of the glass tube 2 to remove the corners generated on the end face 3. The glass tube 2 is a short glass tube and is used for, for example, a reed switch or the like. Here, the outer diameter of the glass tube 2 is "R", the wall thickness is "W", and the total length is "L". In the glass tube 2 of this example, the outer diameter R is set to a value of 1.5 to 2.5 mm, the wall thickness W is set to a value of 0.15 to 0.3 mm, and the total length L is set to a value of 7 to 25 mm. Is set to.

The glass tube end face processing apparatus 1 has a transport unit 4 for transporting the glass tube 2 to be processed for glazing, a preheating source 5 for preheating the end face 3 of the glass tube 2, and an end face 3 of the preheated glass tube 2. The main heating source 6 for main heating is provided. The glass tube end face processing device 1 of this example executes glazing processing of both end faces 3 (first end face 3a and second end face 3b) of the glass tube 2.

The transport unit 4 includes a transport block 7 capable of transporting a plurality of glass tubes 2 for preheating and main heating the glass tubes 2. The transport unit 4 of this example transports a plurality of glass tubes 2 at a constant speed. On the upper surface of the transport block 7, a plurality of concave mounting portions 8 arranged at equal intervals along the transport direction (direction of arrow A in FIG. 1) are provided, and the glass tube 2 is arranged in the mounting portions 8. .. The transport block 7 is formed of, for example, black alumite.

The preheating source 5 is a heat source provided for preheating the glass tube 2, and preheats the end surface 3 of the glass tube 2 by irradiating the laser LA1 (preheating laser). As the preheating source 5, for example, a CO ₂ laser is used. The preheating source 5 preheats the end face 3 of the glass tube 2 by a preheating beam having a Gaussian distribution. In the preheating of this example, the laser LA1 having an output wattage of "20 to 30 W" is irradiated for "0.5 to 1 second". The preheating source 5 is arranged obliquely in a plan view with respect to the transport direction A of the glass tube 2, so that the end surface 3 of the glass tube 2 is obliquely irradiated with the laser LA1 to perform preheating. The plurality of preheating sources 5 (first preheating source 5a, second preheating source 5b) are configured to output light branched from a common light source (not shown) to each, and the preheating sources 5 are arranged diagonally. Thereby, a plurality of first preheating sources 5a and second preheating sources 5b can be laid out with a high degree of freedom.

The main heating source 6 is a heat source provided for main heating of the glass tube 2 after preheating, and the end face 3 of the glass tube 2 is mainly heated by irradiating the laser LA2 (main heating laser). The main heating source 6 mainly heats the end face 3 of the glass tube 2 by a line beam. In this heating of this example, the laser LA2 having an output wattage of "30 to 45 W" is irradiated for "0.1 to 0.3 seconds". By arranging the main heating source 6 at an angle orthogonal to or near the transport direction A of the glass tube 2, the laser LA2 is irradiated substantially perpendicular to the end surface 3 of the glass tube 2 to perform the main heating. do.

A plurality of sets of the preheating source 5 and the main heating source 6 are provided corresponding to each of both end faces 3 (one first end face 3a and the other second end face 3b) of the glass tube 2. The set of the first preheating source 5a and the first heating source 6a (the set on the first end surface 3a side of the glass tube 2) is arranged on the upstream side in the transport direction A, and the second preheating source 5b and the second heating source are arranged. The set of 6b (the set on the second end surface 3b side of the glass tube 2) is arranged on the downstream side in the transport direction A. Thereby, in the preheating and the main heating, the treatment on one first end surface 3a of the glass tube 2 and the treatment on the other second end surface 3b of the glass tube 2 are carried out in order.

As shown in FIG. 3, the irradiation range Ea of the laser LA1 of the preheat source 5 is set to a range that hits a plurality of glass tubes 2. As described above, the irradiation range Ea of the laser LA1 of the preheating source 5 is set so as to have an area sufficiently larger than the area of the end face 3 of the glass tube 2. Therefore, the preheating source 5 simultaneously preheats the end faces 3 of the plurality of glass tubes 2. The irradiation range Ea of the laser LA1 of the preheating source 5 and the irradiation range Eb of the laser LA2 of the main heating source 6 are arranged so as to overlap each other. That is, the preheating source 5 and the main heating source 6 are arranged so that the irradiation ranges of the heat rays irradiated by each overlap each other. In the case of this example, a part of the irradiation range Ea of the preheating source 5 and a part of the irradiation range Eb of the main heating source 6 are set to wrap.

Subsequently, the procedure of the glazing treatment of the end face 3 of the glass tube 2 will be described with reference to FIG.
As shown in FIG. 3A, the glass tube 2 is arranged in the transport section 4 that operates in the transport direction A at a constant speed, and the glass tube 2 is transported at a constant speed. When a plurality of glass tubes 2 are mounted on the transport unit 4, these glass tubes 2 are evenly arranged in the transport direction A.

As shown in FIG. 3B, when one of the first end faces 3a of the glass tube 2 enters the irradiation range Ea of the laser LA1 of the first preheat source 5a, the preheating of the first end face 3a of the glass tube 2 is started. (Preheating process). At this time, the first end surface 3a of the glass tube 2 is preheated by the laser LA1 of the first preheating source 5a, that is, the _CO2 laser. In the case of this example, since the output intensity of the laser LA1 of the first preheat source 5a has a Gaussian distribution along the irradiation surface direction, the first end surface is gradually increased in temperature as it approaches the center from the outside of the irradiation range Ea. 3a is heated. Further, since the irradiation range Ea of the laser LA1 of the first preheating source 5a is formed in a range sufficiently larger than the area of the first end surface 3a of the glass tube 2, the first end faces 3a of the plurality of glass tubes 2 are preheated at the same time. Will be done.

As shown in FIG. 3C → FIG. 3D, when the first end surface 3a of the glass tube 2 reaches the irradiation range Eb of the laser LA2 of the first heating source 6a, the first end surface 3a of the glass tube 2 is reached. The main heating of the glass is started (main heating step). In the case of this example, the laser LA2 of the first heating source 6a is a line beam whose beam loci intersect with respect to the transport direction A of the glass tube 2. Further, when the beam width of the line beam is T, the inclination angle of the beam locus with respect to the transport direction A is θ, and the outer diameter of the glass tube 2 is R, the following equation (1) is satisfied.
T × sin θ ≧ R… (1)
Therefore, even when heating is performed by the line beam, the entire area of the first end surface 3a of the glass tube 2 can be uniformly heated.

Subsequently, when the glass tube 2 reaches the second preheating source 5b and the second heating source 6b, the second end surface 3b on the opposite side of the glass tube 2 also has the second preheating source 5b and the same as the first end surface 3a side. Glazing is performed by the second heating source 6b. When both end faces 3 of the glass tube 2 are heated and melted by the laser and cooled, the end face 3 becomes a glaze surface (fire-making surface) 9 and the glazing process is completed.

Next, the operation and effect of the glass tube manufacturing method (glass tube 2) of the present embodiment will be described with reference to FIGS. 4 to 6.
FIG. 4 illustrates the temperature change in each case of preheating and non-preheating in the glass tube end face glazing process. As shown in the figure, in the case of "no preheating", the temperature rises sharply from the start of the main heating, and the maximum heating temperature rises. On the other hand, in the case of "preheating", the temperature is gradually raised by preheating, so that the maximum temperature can be lower than that in the case of "without preheating".

By the way, as an index related to the breakage of the glass tube 2, there is "residual stress" remaining in the glass tube 2 after the glazing process. It is generally said that when this residual stress exceeds 7 MPa, the risk of fracture increases. Therefore, there is a need to suppress the residual stress of the glass tube 2 to 7 Ma or less.

The residual stress is related to the slope of the temperature drop during cooling of the glazing process, specifically, the temperature gradient Δt when the temperature reaches the strain point from the slow cooling point. If the temperature gradient Δt is rapid, that is, if the cooling is rapid, the residual stress becomes large, and if the temperature gradient Δt is gentle, the residual stress becomes small. As in this example, it was found that the temperature gradient Δt (with preheating: Δta, without preheating: Δtb) becomes gentle when there is a preheating step in the glazing process. From this, it can be assumed that the residual stress is small.

Further, when the glazing process is performed only with the main heating source 6 without preheating, the laser output needs to be 45 to 60 [W], and in this case, the residual stress is actually measured to take a value of 9 to 11 [MPa]. Was done. On the other hand, when the glazing process is performed with preheating (preheating laser output: 20 to 30 [W]), the laser output of this heating is only 30 to 45 [W] and the residual stress is 2 to 7 [MPa]. It turned out that it can be suppressed to. Therefore, it can be seen from this that the residual stress can be suppressed to a low level. Therefore, it can be seen that the risk of breakage (easiness of breakage) can be suppressed.

FIG. 5 illustrates the position where the tensile stress (strain) generated in the glass tube 2 after the glazing process without preheating is generated. Here, the above-mentioned residual stress includes tensile stress (strain), compressive stress, and the like, and tensile stress (strain) is the main parameter that is largely related to the fracture of the end face 3 of the glass tube 2. As shown in the figure, it was found that when no preheating is performed in the glazing process, tensile stress (strain) is generated at a position near the end of the glass tube 2 (for example, a position about 0.4 mm from the end face 3). This leads to the risk of breakage (easiness of breakage).

FIG. 6 illustrates the position where the tensile stress (strain) generated in the glass tube 2 after the glazing process when preheated is generated. As shown in the figure, it was found that when preheating is performed in the glazing process, the tensile stress (strain) moves inward from the end surface 3 of the glass tube 2 (in the direction of arrow U in the figure). Here, the glass tube 2 has a maximum residual stress F at a position D of "0.5 to 1 mm" in the axial direction (long direction) from the end face 3, and the maximum value of the residual stress F is "2 to 7 MPa". It becomes. As described above, in the case of this example, in the glazing process, the position where the tensile stress (strain) is generated can be separated from the end face 3 when the preheating is performed as compared with the case where the preheating is performed. Therefore, it leads to the suppression of the risk of breakage (easiness of breakage). The magnitude and position of the residual stress were measured using a polarizing microscope ECLOPSE E600 POL manufactured by Nikon Corporation.

In the case of this example, in the glazing process of the end face 3 of the glass tube 2, the end face 3 of the glass tube 2 is first preheated, and then the end face 3 of the glass tube 2 is mainly heated. Therefore, since the end surface 3 of the glass tube 2 can be heated to some extent before the main heating, the temperature required for the main heating can be kept low. As a result, the temperature gradient Δt for cooling after processing becomes gentle, so that the residual stress generated in the glass tube 2 can be suppressed to a low level. Therefore, the risk of breaking the glass tube 2 can be reduced.

The preheating source 5 is a laser type, and preheats the end face 3 of the glass tube 2 by irradiating a beam having a Gaussian distribution. Therefore, since the preheating range (laser irradiation range Ea) of the preheating source 5 can be widened, the end face 3 of the glass tube 2 can be preheated more reliably. Further, the main heating source 6 is a laser type, and the end face 3 of the glass tube 2 is mainly heated by irradiating the line beam. Therefore, at the time of main heating, the end face 3 of the glass tube 2 can be heated with the required high temperature heat.

In the preheating step, a plurality of glass tubes 2 are preheated at the same time. Therefore, the preheating of the glass tube 2 can be efficiently performed.
A plurality of glass tubes 2 arranged in line in the transport direction A are transported, and preheating and main heating are performed in the transport process. Therefore, since the glass tube 2 is preheated and main heated while being conveyed at a predetermined speed (in this example, a constant speed), the preheating and main heating can be efficiently performed. Further, if the transport speed of the glass tube 2 is constant, it is possible to prevent uneven heating during preheating and main heating.

In the preheating step, the preheating source 5 is arranged diagonally with respect to the transport direction A of the glass tube 2, and the end surface 3 of the glass tube 2 is heated diagonally to perform preheating. In this example, when the light of one light source (not shown) is branched to reach a plurality of preheating sources 5 and the laser LA1 is irradiated from these preheating sources 5, these preheating sources 5 are arranged diagonally. It is possible to set the optimum orientation between one light source and the plurality of preheat sources 5. In this way, the light source (not shown) can be shared among the plurality of preheat sources 5, which is advantageous in suppressing the equipment cost.

Further, in the main heating step, the main heating source 6 is arranged at an angle orthogonal to or near the transport direction A of the glass tube 2 and irradiated with the laser LA 2 substantially perpendicular to the end surface 3 of the glass tube 2. Perform this heating. Therefore, the laser of the main heating source 6 can be firmly applied to the end surface 3 of the glass tube 2, which is advantageous for efficiently performing the main heating.

The preheating source 5 and the main heating source 6 are arranged so that the irradiation ranges (irradiation ranges Ea and Eb) of the heat rays irradiated by each overlap each other. Therefore, the end surface 3 of the glass tube 2 can be smoothly transferred from the preheating to the main heating, which is advantageous for optimally glazing the end surface 3 of the glass tube 2.

The preheating step and the main heating step are sequentially performed on each of one end surface 3 (first end surface 3a) of the glass tube 2 and the other end surface 3 (second end surface 3b) of the glass tube 2. Therefore, both end faces 3 of the glass tube 2 can be glazing.

In the preheating step, preheating is performed by irradiating a laser LA1 having an output wattage of 20 to 30 W for 0.5 to 1 second. Therefore, the wattage and preheating time of the preheating laser can be optimized.

In this heating step, when the beam width of the line beam is T, the inclination angle of the beam locus (optical axis) with respect to the transport direction A of the glass tube 2 is θ, and the outer diameter of the glass tube 2 is R, “T ×”. This heating is performed so as to satisfy the relationship represented by “sin θ ≧ R”. Therefore, the main heating can be carried out under the optimum conditions.

In addition, this embodiment can be changed and carried out as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-A plurality of glass tubes 2 may be simultaneously heated in both the preheating and heating steps, or a plurality of glass tubes 2 may be simultaneously heated in only one of these steps.

-The preheating source 5 is not limited to the CO ₂ laser, and may be changed to a laser of another type.
The main heating source 6 is not limited to the line beam type, and may be a laser having a Gaussian distribution in output, such as a preheating source 5.

-The preheating source 5 and the main heating source 6 are not limited to the laser type, and other types of heat sources may be used.
-Preheating is not limited to being performed in a plurality of glass tubes 2 at the same time, and may be performed one by one.

-Both end faces 3 of the glass tube 2 may be glazing processed at the same timing.
-As the preheating method, various modes such as switching the preheating temperature to a plurality of stages in the middle of processing can be applied. This also applies to the main heating.

The glass tube end face processing device 1 may be a device having a plurality of lines in which a plurality of transfer blocks 7 are arranged.
The method of transporting the glass tube 2 can be changed to various modes as long as the glass tube 2 can pass through the laser irradiation ranges of the preheating source 5 and the main heating source 6.

The preheat source 5 is not limited to being arranged diagonally with respect to the transport direction A of the glass tube 2, and may be arranged in a direction orthogonal to the transport direction A.
-The laser irradiation ranges of the preheating source 5 and the main heating source 6 are not limited to partially wrapping, and the irradiation ranges may not overlap at all.

-As for the glazing treatment, various treatments can be applied as long as the end face 3 of the glass tube 2 can be rounded by softening and heating.
-The glass tube 2 is not limited to short glass, and may be changed to a glass tube having a certain length.

1 ... Glass tube end face processing device, 2 ... Glass tube, 3 ... End face, 3a ... First end face, 3b ... Second end face, 5 ... Preheating source, 5a ... First preheating source, 5b ... Second preheating source, 6 ... Main heating source, 6a ... 1st heating source, 6b ... 2nd heating source, 9 ... glaze surface, A ... transport direction, LA1 ... laser, LA2 ... laser, Ea, Eb ... irradiation range.

Claims (11)

It is a glass tube manufacturing method that glazing the end face of the glass tube.
A preheating step of preheating the end face of the glass tube with a preheating source, and
It is provided with a main heating step of main heating the end face of the glass tube after the preheating step by the main heating source .
The preheating source is a laser type, and the end face of the glass tube is preheated by irradiating the end face of the glass tube with a beam of Gaussian distribution.
A method for manufacturing a glass tube having an irradiation range in which the beam of the Gaussian distribution of the preheating source includes the entire end face of the glass tube. The glass tube manufacturing method according to claim 1, wherein the main heating source is a laser type, and the end face of the glass tube is mainly heated by irradiating the end face of the glass tube with a line beam. The glass tube manufacturing method according to claim 1 or 2, wherein in the preheating step, a plurality of the glass tubes are preheated at the same time. The glass tube manufacturing method according to any one of claims 1 to 3, wherein a plurality of the glass tubes arranged in a line in the transport direction are transported, and the preheating and the main heating are performed in the transporting process. The glass tube manufacturing method according to claim 4, wherein in the preheating step, the preheating source is arranged diagonally with respect to the transport direction of the glass tube, and the end face of the glass tube is heated diagonally to perform the preheating. .. The glass tube manufacturing method according to any one of claims 1 to 5, wherein the preheating source and the main heating source are arranged so that the irradiation ranges of the heat rays irradiated by each are arranged so as to overlap each other. The glass according to any one of claims 1 to 6, wherein the preheating step and the main heating step are sequentially performed on each of one end face of the glass tube and the other end face of the glass tube. Tube manufacturing method. The glass tube manufacturing method according to any one of claims 1 to 7, wherein in the preheating step, preheating is performed by irradiating a laser having an output wattage of 20 to 30 W for 0.5 to 1 second. In the main heating step carried out by the line beam of the laser, the beam width of the line beam is T, the inclination angle of the beam locus (optical axis) with respect to the transport direction A of the glass tube is θ, and the outer diameter of the glass tube is set. When R is used, the following equation (1):
T × sin θ ≧ R… (1)
The glass tube manufacturing method according to any one of claims 1 to 8, wherein the main heating is performed so as to satisfy the relationship represented by. The glass tube obtained by the main heating step is a glass tube whose end face is a glaze surface, and the residual stress is maximum at a position of 0.5 to 1 mm in the axial direction from the end face, and the maximum value of the residual stress is The glass tube manufacturing method according to any one of claims 1 to 9, which is 2 to 7 MPa. A glass tube end face processing device that glazing the end face of a glass tube.
A preheating source for preheating the end face of the glass tube and
A main heating source for main heating the end face of the preheated glass tube is provided .
The preheating source is a laser type, and the end face of the glass tube is preheated by irradiating the end face of the glass tube with a beam of Gaussian distribution.
The beam of the Gaussian distribution of the preheating source is a glass tube end face processing apparatus having an irradiation range including the entire end face of the glass tube.

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