JP3503960B2 - Manufacturing method of small tube - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a small tube, and more particularly to an improvement in a method for manufacturing a small tube by a bead seal method. 2. Description of the Related Art Small light bulbs sealed by a so-called bead seal method are widely used as light sources for display or illumination of, for example, OA equipment and audio equipment. And this kind of small tube is generally manufactured as follows. For example, outer diameter 2.4 ~ 6mm
, One end of a thin glass tube with a wall thickness of about 0.3 to 0.4 mm is sealed and the top is formed in a hemispherical shape, while the other end is extended.
First, a bulb valve in which an exhaust pipe portion is integrally formed by opening is prepared. Then, a bead mount made of a pair of lead wires and bead glass, on which a light emitting filament is mounted, is inserted from the exhaust pipe side of the bulb bulb, and the bead mount is positioned inside the bulb bulb. Thereafter, a predetermined portion of the exhaust pipe portion is heated and softened to reduce the diameter with reference to the hemispherically formed top portion of the bulb valve to form a portion to be sealed, and then the open end of the exhaust pipe portion is exhausted. Insert it vertically into the opening rubber and evacuate the tube bulb. After the evacuation step, the portion to be sealed of the exhaust pipe portion is heated from the outer periphery, and the bead glass which is close to and sealed in this region and the portion to be sealed of the exhaust pipe portion are melted and sealed. After sealing with the bead seal method, a part of the exhaust pipe is cut in a portion to be cut in a form leaving a sealing portion of the exhaust pipe, for example, with a cutter, and the exhaust pipe is cut off from the scratch as a starting point. Cutting (separation) and removal (for example,
No. 2638). The above-mentioned manufacturing method is mass-produced and can be satisfied, but has the following problems. In other words, the unnecessary exhaust pipe section is cut and removed, in other words, a part of the exhaust pipe section is partially damaged while leaving the sealing section of the exhaust pipe, and the exhaust pipe section is cut and removed starting from the scratch. In the case of the method of cutting, the cut part is often slanted, or the burr-like projection remains at the cut part, often not forming a smooth cut surface. Out of range also occurs. That is, the small tube often deviates from the standard relating to its entire length, which not only affects the yield, but also has a burr-like projection on the cut portion even if the dimensional standard is satisfied. In addition, there is a risk that the worker may be injured in the process of introducing the small tube and assembling the holder. In order to cope with such a problem, after the above-described exhaust pipe section is cut and removed, all the small-sized bulbs in which the burr-like projections are left at the cut section are individually selected by manual burr cutting (burr-like cutting). (A step of cutting the projection again). However, the addition of the 100% sorting and the varicutting process not only complicates the process or increases the number of steps, but also causes damage to the sealing portion due to a cutting mistake. In other words, the yield is reduced, which is a serious problem in terms of mass productivity. [0005] The present invention has been made as a result of studying in consideration of the above circumstances, and a small tube having a uniform overall length has been developed.
An object of the present invention is to provide a method for manufacturing a small tube that can be manufactured stably and easily. SUMMARY OF THE INVENTION A method of manufacturing a small tube according to the present invention is directed to a bead made of a pair of lead wires and bead glass in which a filament is mounted on a tube bulb integrally formed with an exhaust pipe. An evacuation step of inserting a mount, positioning a bead mount inside the bulb bulb, and evacuating the vessel, and sealing or welding a bead glass of the bead mount to an exhaust pipe of the bulb bulb and sealing it by a bead seal method. In a method for manufacturing a small-sized bulb comprising a sealing step of stopping and a step of cutting and removing an exhaust pipe while leaving a sealing portion by the bead glass, when the exhaust pipe is cut and removed, the sealing section Near the boundary area between the body and the body of the exhaust pipe
The heating means is moved to
To the body while avoiding the sealing part and the boundary area.
Definitive said heating location portion in the vicinity of the boundary region, characterized in that it cleaved off causing the thermal shock at the ring-shaped cracks on the boundary region. In the present invention, the exhaust pipe is heated close to (close to) the exhaust pipe body while avoiding the sealing section and the boundary area between the sealing section and the body of the exhaust pipe. A direct heating means such as a gas burner is arranged, and the frame is cut off at the body part while avoiding the sealing part and the boundary area.
This can be achieved by hitting a portion located near the boundary region . Generally, in the exhaust pipe, the boundary area between the sealing portion and the body of the other exhaust pipe is also a boundary where a difference in heat capacity occurs due to a difference in wall thickness. Therefore, in the boundary region, a slight linear distortion occurs in the circumferential direction due to a difference in cooling rate after the heat sealing in the previous step (sealing step), and this remains. Therefore, in the method for manufacturing a small tube according to the present invention, in cutting and removing the exhaust pipe, the body is formed while avoiding the sealing portion and the boundary region.
By heating the portion located near the boundary region in the part , a local thermal shock is applied to the boundary region between the sealing portion and the body of the exhaust pipe by conduction heat, causing linear distortion, Along with the distortion, a ring-shaped crack is generated with high accuracy.
In this way, the exhaust pipe can be easily cut and removed from the cracked portion, and a small-sized bulb having a substantially uniform overall length within the standard and a smooth cut surface can be manufactured easily and with good yield. . An embodiment of the present invention will be described below with reference to FIG. 1 and FIGS. 2 (a) and 2 (b). FIG. 1 is a schematic diagram showing a main part of an embodiment of a method for manufacturing a small tube according to the present invention, and FIGS.
(b) schematically shows an embodiment of the method for producing a small tube according to the present invention. First, steps such as interior of a bead mount, formation of a portion to be sealed, evacuation, and sealing of a portion to be sealed are performed by a conventional manufacturing apparatus or means. That is, a small bulb bulb (for example, a small glass tube having an outer diameter of 3.0 mm and a wall thickness of 0.3 mm and sealed at one end) having an exhaust pipe integrally formed is prepared, and the inside thereof is cleaned.
The interior of the bead mount, formation of the portion to be sealed of the exhaust pipe (diameter reduction by heating), vacuum evacuation treatment, and sealing (welding) with the bead glass by heating the portion to be sealed were sequentially performed. After the completion of the heat sealing, the process proceeds to a step of cutting and removing unnecessary exhaust pipe portions outside the sealed portion. The process of cutting and removing the exhaust pipe portions is shown in FIG. This is performed by a mechanism configured as shown. That is, a plurality of valve holders 1 having holding holes 1a are vertically arranged at equal intervals on a chain conveyor (not shown) that moves intermittently. When the bulb bulb 2 is stopped while being held substantially vertically, an open / close type exhaust pipe chuck 3 arranged to sandwich the exhaust pipe section 2a from both sides, and a chuck opening / closing means 4 for opening and closing the exhaust pipe chuck 3 And the chuck opening / closing means 4
First, an apparatus having a mechanism including a chuck elevating means 5 for elevating and lowering the gas and a gas burner 6 for selectively heating the vicinity of the planned cutting portion 2b of the exhaust pipe portion 2a of the heat sealed small bulb valve 2 is prepared. Is done. In this device configuration, the exhaust pipe chuck 3 has a V-shaped groove at its tip and a convex portion engaging with the V-groove so that the exhaust pipe 2a (intermediate portion) of the small bulb valve 2 can be clamped. A pair of chuck claws 3a, 3a 'formed respectively.
Are attached to the chuck opening / closing means 4 via chuck supports 3b and 3b ', respectively. Further, the chuck opening / closing means 4 is supported by a chuck elevating means 5 so as to be vertically movable, and the chuck claws 3a, 3a '
It is configured to be openable and closable by the chuck opening / closing means 4 and to move up and down together with the chuck opening / closing means 4.
Further, the chuck supports 3b, 3
A gauging plate 7 is fixedly disposed above the space between the chuck supports 3b and 3b ', and is located on the upper side of the exhaust pipe portion 2a of the small bulb valve 2 which is stationary between the chuck supports 3b and 3b'. The gas burner 6 is disposed close to the gas burner 6, and the gas burner 6 is supported by a burner raising / lowering means 8 provided at a rear portion thereof so as to be movable up and down. Further, a heat shield plate 9 is disposed above the gas burner 6 in the vicinity of the side of the cut-out scheduled portion 2b of the exhaust pipe of the stationary small bulb valve 2. The above configuration constitutes the first stage of the cutting / removing step. The chuck opening / closing means 4, the chuck lifting / lowering means 5, and the burner lifting / lowering means 8 can be easily configured using, for example, an air cylinder or a slide mechanism with a built-in air cylinder. In addition, the means and configuration for cutting the exhaust pipe section 2a are linked to each process such as vacuum exhaust performed by intermittent transfer by the above-described chain conveyor (a rotary table is also possible). Automation is also possible. Further, following the preceding stage of the cutting / removing step, means for separating the exhaust pipe portion 2a is arranged in proximity to the exhaust pipe section 2a.
This is the latter stage of the cutting / removing process. That is, in response to the predetermined position at which the valve holder 1 is moved and stopped by the intermittent drive of the chain conveyor, the small bulb valve 2 is held by the valve holder 1,
Means for breaking off the head, that is, the small tube portion 2c, is arranged in the vicinity, and constitutes the latter stage of the cutting / removing step. Next, the operation of the mechanism and means for cutting and removing the exhaust pipe section 2a will be described. First, the exhaust pipe portion 2a of the small bulb valve 2 which has been heated and sealed by a conventional method is inserted into the holding hole 1a of the valve holder 1 and vertically held.
In this state, the chain conveyor constituting the transport mechanism is intermittently driven, and the bulb valve 2 is stopped at a predetermined position between the chuck supports 3b and 3b 'of the exhaust pipe chuck 3, as shown in FIG. Let it. Then, the gas burner 6 is immediately ignited and heating is started. Then, as shown in FIG.
While continuing heating by the frame 6a of the gas burner 6,
The chuck opening / closing means 4 is operated to hold the intermediate portion of the exhaust pipe section 2a by the chuck claws 3a and 3a ', and the chuck elevating means 5 is operated to move up while the exhaust pipe section 2a is held vertically. Let it. Thus, the top of the small bulb valve 2
The exhaust pipe chuck 3 is moved up to a position where 2d comes into contact with the gauging plate 7 to position the scheduled cutting portion 2b of the exhaust pipe. Note that this positioning means is a means for accurately abutting the frame 6a of the gas burner 6 near the scheduled cutting portion 2b, avoiding the sealing portion 2e of the exhaust pipe. That is, the exhaust pipe
When the lengths of the parts 2a vary from one another, the height of the scheduled cutting part 2b changes while the lower end is held by the valve holder 1 so that the frame 6a of the gas burner 6 can be accurately positioned at a predetermined position. I can't hit it. Therefore, the apical portion 2d of the small bulb valve 2 is brought into contact with the gauging plate 7, so that the cut portion 2b is accurately positioned from the small bulb portion 2c. Subsequently, at the same position, as shown in FIG. 2 (b), the burner raising / lowering means 8 is operated to move the gas burner 6 upward by a predetermined height, so that the vicinity of the cut portion 2b of the exhaust pipe is to be cut. Continue heating. By such heating, a thermal shock is applied to the scheduled cutting portion 2b, and a ring-shaped crack is generated over substantially the entire circumference along the linear distortion remaining there. Next, the valve holder 1 is intermittently moved, and the head portion of the bulb valve 2, that is, the small bulb portion 2c is cut off from the cracked portion by a cutting means arranged at a later stage to separate the exhaust pipe portion 2a, and a cutting and removing step is performed. To end. In this manner, it is possible to cut a flat surface without a burr-like projection or the like on the cut surface, and to obtain a small-sized tube with good dimensional accuracy of the entire length (uniform overall length). Further, at the time of heating, since the sealing portion 2e and the scheduled cutting portion 2b are protected by the heat shield plate 9, the frame 6a of the gas burner 6
Does not hit directly, and unnecessary cracks do not occur. In the present invention, the target small tube is not limited to the above-described size, but a valve for a small tube and a bead mount integrally formed with an exhaust pipe portion are used. The present invention can be applied to a manufacturing method employing a bead seal method for sealing a bead glass and an exhaust pipe of a valve. According to the method for producing a small tube of the present invention,
Boundary area in the torso while avoiding the seal and border area
By heating the portion located in the vicinity of , a local thermal shock is applied to the boundary region between the sealing portion and the body of the exhaust pipe, and this thermal shock generates a linear distortion, A ring-shaped crack is generated along. And since such a ring-shaped crack is generated at a desired position with high accuracy, a small-sized bulb having a substantially uniform overall length within a standard and a cut surface exhibiting smoothness can be easily produced with high yield and productivity. Can be manufactured well.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing an outline of a main configuration of an apparatus used for carrying out a method for manufacturing a small tube according to the present invention. FIG. 2 schematically shows a main part of an embodiment (operation) of the method for manufacturing a small tube according to the present invention, wherein (a) is a side view showing a state at the beginning of heating of a portion to be cut, (b) is a side view showing the state of the scheduled cutting section at the end of heating. [Description of Signs] 1… Valve holder 1a… Holding hole 2… Tube valve
2a: Exhaust pipe section 2b: Planned cutting section 2c: Small tube bulb section 2d: Top section 2e
... Seal part 3 ... Exhaust pipe chuck 3a, 3a '... Chuck claw 3b, 3b' ... Chuck support 4 ... Chuck opening / closing means 5 ... Chuck elevating means 6 ... Gas burner
6a: Frame 7: Gauging plate 8: Burner elevating means 9: Heat shield plate

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01K 1/00-13/06

Claims (1)

(57) [Claim 1] A bead mount made of a pair of introductory wires and bead glass on which a filament is mounted is inserted into a bulb valve integrally formed with an exhaust pipe, and the inside of the bulb valve is inserted. An evacuation step in which a bead mount is positioned inside the evacuation apparatus and a vacuum evacuation is performed; a bead glass of the bead mount is sealed or welded to an evacuation pipe of the bulb valve to seal by a bead seal method; the method of manufacturing a small tube comprising a step of cutting and removing the exhaust pipe leaving the sealing portion by the glass, upon cutting and removing the exhaust pipe, the said sealing portion
Move the heating means to the vicinity of the boundary area between the exhaust pipe and the body.
The sealing unit and the
Avoiding the boundary area while avoiding the boundary area
A method for manufacturing a small-sized bulb, comprising heating a portion located in the vicinity, and generating a ring-shaped crack in the boundary region by the thermal shock to cut and remove the portion.