JP5789882B2 - Manufacturing method of cylindrical current fuse - Google Patents

Description

  The present invention relates to a method for manufacturing a cylindrical current fuse suitable for surface mounting on a substrate of an electronic device or the like.

  Various types of small current fuses that can be surface-mounted on a printed circuit board have been proposed. For example, Patent Document 1 discloses a method in which a fusible wire is stretched around a case main body made of a cylindrical ceramic with a through-hole provided therein, a metal cap is fitted, and then heated to fix the wire. A small current fuse manufactured by is disclosed.

  However, this fuse employs a system in which when a fusible wire is stretched, the wire end is pulled out, a cap is fitted, the wire is connected and fixed by heating, and then the wire is cut. . For this reason, when a cap electrode is fitted to the ceramic cylinder, an excessive tension (tension by fitting) may be applied to the fusible wire due to the frictional force between the fusible wire and the cap. Further, if the wire is loosened and stretched so as not to apply too much force to the fusible wire, the amount of movement of the wire due to friction when the cap electrode is fitted is not constant, and there is a problem that the looseness of the wire varies. When the wire is loosened, the wire length is not stable, and the fusing property is not stable because the wire adheres to the side surface of the ceramic cylinder. Furthermore, it is necessary to process a groove for accommodating the soluble wire in the ceramic case, which causes a problem that the structure becomes complicated.

  Patent Document 2 discloses a method of temporarily fixing a wire before fitting an outer cap by soldering or spot welding (FIGS. 1 and 2). However, wire temporary fixing by soldering only bends the wire and holds it with the rigidity of the wire, and is unstable, and the wire wire is limited to a thick and rigid material. In addition, the method of temporarily fixing the wires one side at a time by spot welding (FIG. 5) requires that the inner cap be bonded with an adhesive in advance in order to weld the wires, and the cost is increased because the cap is doubled In addition, since the wire stretching, wire temporary fixing, and wire cutting are complicated and multistage, it cannot be said that the manufacturing process is a simple method. Moreover, there is a possibility that the wire may be damaged at the corner of the inner cap, and there is no suggestion of a solution to the problem of temporarily fixing the wire so as not to damage the wire and stretching it without slack.

JP-A-6-342623 Japanese Patent No. 3146012

  The present invention has been made based on the above-mentioned circumstances, and a fusible body wire is stretched so as not to be slanted and slackened in the through hole of the ceramic cylinder body, and both ends of the wire are attached to both end faces of the cylinder body. It is an object of the present invention to provide a method for manufacturing a cylindrical current fuse, in which a process of temporarily fixing and cutting is continuously performed.

The method for manufacturing a cylindrical current fuse of the present invention includes a solder forming step of attaching solder to an opening communicating with the through hole of a ceramic cylinder having a through hole, and a fusible body in the through hole of the ceramic cylinder. A wire passing step for passing the wire, a wire stretching step for gripping the end of the wire passed through the ceramic cylinder with a chuck, and obliquely stretching the wire in the through hole in a state where a predetermined tension is applied, and a wire A wire bonding step of fixing the wire to the opening of the ceramic cylinder through the solder and cutting the wire, the wire bonding step bringing the wire into contact with the opening of the ceramic tube, and the contact of the wire The portion is heated and fixed to the opening of the ceramic cylinder through solder, and the tension is applied to break the wire .

  The wire is fixed at the primary (front) end surface of the wire by applying tension tension to the wire, and the fixing portion to the end surface of the wire is directly brought into contact with the heating chip and fixed to the solder to break the wire. . When fixing the secondary side (rear) end surface of the wire, heat the tip of the heating tip so that it does not touch the wire directly, and fix the end surface fixing part of the wire to the solder while applying tension on the secondary side end surface. Break. The wire cutting at the secondary side end face breaks the wire while applying tension to the wire in a direction having an angle from the creeping end face of the ceramic cylinder to the direction of the cylinder.

It is sectional drawing of the step which formed eyelet-like solder on the ceramic cylinder end surface, and stretched and cut | disconnected the soluble body wire diagonally without slack. It is sectional drawing of the step which formed eyelet-like solder in the through-hole edge part of a ceramic cylinder. It is sectional drawing of the step which inserted the soluble body wire covered with the wire guide in the through-hole of the ceramic cylinder. It is sectional drawing of the step which hold | maintains one end of a soluble body wire temporarily with a chuck | zipper, and pulls out a wire guide. FIG. 5 is a cross-sectional view of a stage in which a fusible wire is passed through a ceramic cylinder, both ends of the wire are held by a chuck, and the ceramic cylinder is held by a gripping portion of a rotary jig. It is sectional drawing of the step which rotated the ceramic cylinder 90 degree | times with the rotation jig, and tensioned the wire diagonally in the ceramic cylinder. It is sectional drawing of the step which pressed and supported the heater chip | tip on the both end surfaces of the ceramic cylinder. It is sectional drawing of the step of fixing the wire in a primary side end surface to solder. It is sectional drawing of the step of fixing and cutting the wire in a primary side end surface to solder. It is sectional drawing of the step of fixing the wire in a secondary side end surface to solder. It is sectional drawing of the step which fixes and cut | disconnects the wire in a secondary side end surface to solder.

  Embodiments of the present invention will be described below with reference to FIGS. 1 to 6B. In addition, in each figure, the same code | symbol is attached | subjected and demonstrated to the same or equivalent member or element.

  FIG. 1 shows a state in which a wire is temporarily fixed to an end of a cylindrical body in the cylindrical current fuse of the present invention. This fuse has a ceramic cylinder 11 provided with a through-hole 12 therein, an electrode cap 18 (shown by a broken line) that is fitted to both ends of the cylinder in a later step, and an internal penetration of the cylinder. It is a cylindrical current fuse provided with a fusible wire 16 stretched diagonally in the hole 12 without slack. A grommet-like solder 15 formed from the end surface of the cylindrical body 11 to the inner peripheral surface of the through hole is provided, the wire 16 is temporarily fixed to the end surface side of the cylindrical body of the solder 15, and the cap 18 is fitted and then heated. Then, the wire 16 is connected and fixed to the inner surface of the cap 18 with solder.

  The end of the wire 16 does not reach the outer periphery of the cylinder 11. That is, the end portion of the wire 16 is fixed to the solder 15 provided on the end surface of the cylindrical body 11 and is cut at that portion. At the end of the wire 16, when the cap 18 is connected and fixed later, the solder 15 covering the edge of the through hole 12 and the solder loaded in the cap 18 are melted, and both ends of the through hole 12 are integrated with the integrated solder. The end of the wire 16 is connected and fixed to the inner surface of the cap 18. Note that the end of the wire 16 may be connected and fixed to the inner surface of the cap 18 with only the solder 15 covering the edge of the through hole 12.

  2 to 6B show a method of manufacturing a cylindrical current fuse according to an embodiment of the present invention. First, a ceramic cylinder 11 having a substantially prismatic outer shape provided with a through hole 12 therein is prepared. And in the state which stood the cylinder 11, the disk-shaped solder board is arrange | positioned on the end surface of the cylinder 11. FIG. The solder plate is preferably formed by using lead-free and hard Sn—Cu 4-15% solder.

  Then, a punch (punching) is punched from the solder plate into the through hole 12. As a result, the solder plate is deformed, and as shown in FIG. 2, a ring-shaped solder portion 15a is formed on the edge portion (corner portion) of the through hole 12 on the end surface of the ceramic cylinder 11, and the through hole is formed from the solder portion 15a. Eyelet-like solder 15 is formed, which is composed of a solder portion 15b extending on the inner peripheral surface. In the eyelet-shaped solder 15, a smooth curved surface R is formed from the end surface of the cylindrical body 11 to the inner peripheral surface. As shown in the figure, eyelet-like solder 15 is formed on both end faces of the cylinder 11.

  Next, as shown in FIG. 3A, the fusible wire 16 covered with the wire guide 21 is inserted into the ceramic cylinder 11 in which the solder 15 is formed in the wire passing stage. Since the wire 16 is thin, good workability can be obtained by supporting it with the wire guide 21 having rigidity. Then, as shown in FIG. 3B, after the wire 16 is held and held by the temporary wire holding chuck 25, the wire guide 21 is pulled out to pass the wire 16 into the ceramic cylinder. Then, after the opposite side is held and held by the wire temporary holding chuck 26, the wire is cut by means not shown. Note that the wire guide 21 moves to a portion (not shown) on the left side in the drawing in a state where the wire is passed through the inside.

  Next, as shown in FIG. 4A, the ceramic cylinder 11 through which the wire 16 is passed and both sides are temporarily held is moved to the wire stretching stage while maintaining the tension, and the wire 16 is moved by the wire holding chucks 22 and 23. Hold. The ceramic cylinder 11 is held by the gripping portions 24 a and 24 b of the rotary jig 24. The gripping portions 24a and 24b are fixed to a disk-shaped rotating jig 24, and the rotating jig 24 is rotatable in a direction indicated by a broken-line circle in the drawing.

  At this time, the ceramic cylinder 11 and the wire 16 are arranged in parallel, and are in a positional relationship not in contact with each other. The wire holding chucks 22 and 23 are arranged with a movable shaft that can slide in the direction of the arrow in the figure, and can be freely moved within a necessary range. Further, since the wire holding chucks 22 and 23 are provided with a tension tension F in the outward direction by an elastic member such as a spring, the fusible wire 16 passed through the ceramic cylinder is stretched straight. This completes the wire 16 through the ceramic cylinder 11. In addition, the tension | tensile_strength tension F is enough with the minimum force which can stretch | stretch the wire 16 straightly.

  Next, as shown in FIG. 4B, the ceramic cylinder 11 is rotated 90 degrees (counterclockwise as viewed from above) by the rotating jig 24 while the both ends of the wire 16 are sandwiched between the wire holding chucks 22 and 23. The wire 16 is slanted in the ceramic cylinder 11. At this time, since both ends of the wire 16 are pulled with the tension tension F, the wire 16 is stretched in the ceramic cylinder 11 without slack. The wire holding chucks 22 and 23 move as the wire 16 is pulled by the tension tension F, and prevents a force exceeding the tension tension F from being applied to the wire. In addition, since the eyelet-like solder 15 is formed on the inner edge of the ceramic cylinder 11, the ceramic cylinder inner edge and the fusible wire 16 are not directly rubbed so that they are not damaged.

  Next, as shown in FIG. 4C, the heater chip 17 is pressed against the primary side (lower side in the figure) end surface of the ceramic cylinder 11 and the heater chip 27 is fixed to the secondary side (upper side in the figure) end surface. To do. At this time, the heater chip 17 is pressed so as to cover the entire end surface of the cylindrical body 11 at the primary end surface where the wire is first fixed, and the heater chip 27 is fixed to the wire 16 at the secondary end surface where the second wire is fixed. Eccentrically press so that it does not cover 16a.

  5A and 5B show a state of fixing and cutting the wire to the solder on the primary side end face. When the wire fixing portion 16a on the primary side end surface is heated by energizing the heater chip 17, the wire fixing portion is softened and the solder 15 is melted. The wire holding chucks 22 and 23 have both a movable shaft that freely moves so that the tension tension F is applied to the wire and a movable shaft that applies a force Fa greater than the tension tension F to tear the wire. Here, by applying a large force Fa, the wire breaks, and when the heater chip 17 is de-energized, the solder 15 is solidified, and the end of the wire 16 is fixed to the solder 15 on the primary side end face. That is, in joining the primary side of the wire, while applying tension with the chucks 22 and 23 on both sides of the wire, the tip of the heater chip 17 directly touches the wire, and the primary side of the wire is soldered to the opening of the ceramic cylinder. The wire is broken by applying a large force Fa from the primary side chuck 23 of the wire.

  6A and 6B show the state of fixing and cutting the wire to the solder on the secondary side end face. After the fixing of the end of the primary side wire is completed and the melted solder is cured, the secondary side heater chip 27 is energized, and the wire holding chuck 22 is pulled in the cylinder side direction at an angle A to thereby fix the wire fixing portion. 16a is fixed to the solder 15 and cut at its tip. That is, the bonding of the secondary side of the wire is performed by heating the solder 15 so that the tip of the heater chip 27 does not directly touch the wire 16 and applying a tension with the secondary side chuck 22 of the wire. The secondary side is fixed to the other opening of the ceramic cylinder through the solder 15 and the wire is broken by applying a large force Fa from the secondary side chuck 22 of the wire.

  The heater chip 27 is arranged slightly eccentric from the cylindrical center of the ceramic cylinder 11. Even when the solder is melted by the heat applied by the heater chip 27, the heater chip 27 does not press the wire. Therefore, when the solder is melted by the energization heating, the wire bites into the solder, and at the same time, is pulled outward by the tension tension F and is stretched diagonally and slackly inside the ceramic cylinder while maintaining the tension tension F. Note that the solder 15 gathers at the inner edge of the ceramic cylinder body by the surface tension when melted without applying the force pressed by the heater chip 27. And even if a flaw occurs during the oblique stretching of the wire, it is buried in the solder that has melted and solidified.

  When the wire is broken (tensile cut) on the secondary side, the wire 16 is pulled with a breaking tension Fa at an angle A in the cylinder side direction from the creeping surface of the ceramic cylinder end surface. This angle A is particularly preferably 40 to 50 degrees. Thereby, the wire 16 can be appropriately torn off at the part of the eyelet-like solder 15 or the outer peripheral end face of the ceramic cylinder 11. On the secondary side, since the movable axis direction of the tension F and the movable axis direction of the tension Fa are set to be inclined by 45 degrees, when the ceramic cylinder 11 is rotated using the rotary jig 24, the ceramic cylinder 11 The tension Fa can be applied while maintaining the angle A applied between the end face and the chuck 22.

  The wire breakage at the time of fixing on the primary side is not affected by the pulling direction of the wire 16 because the wire 16 is cut at a place directly pressed by the heater chip 17, but is not affected by the creeping direction of the end surface of the ceramic cylinder. By pulling at an angle similarly to the secondary side, the end surface of the ceramic cylinder can be more reliably broken. On the primary side, the movable axis direction of the tension F and the movable axis direction of the tension Fa are the same. Accordingly, when the tension Fa is applied with the angle A applied and the wire holding chuck 22 is pulled, the angle A changes in a decreasing direction. However, the change in the angle A is small and there is no problem for the above reason. As a result, there is an advantage that the mechanism can be made more suitable for mass production. In addition, as a method of cutting the wire 16, there is a method of cutting using a cutting tool such as a blade in addition to a method of cutting (breaking) with the above-described tension Fa.

  Next, metal caps 18 fitted with solder in advance are fitted to both ends of the ceramic cylinder 11 with the wires 16 stretched inside (see FIG. 1). At this time, since the end portion of the wire does not protrude from the outer peripheral portion of the ceramic cylinder, no tension is applied to the wire when the cap is fitted. Then, by heating for a short time from the outside of the fitted cap, the eyelet-like solder to which the wire is fixed and the solder attached in the cap are melted and integrated to fix the wire and the cap. This completes the current fuse of the present invention.

  As a result, the wire is conventionally drawn out to the outer peripheral surface of the cylinder and accommodated in a groove or the like provided on the outer peripheral surface, but such a complicated structure is not necessary. Moreover, since it fixes to the solder of the ceramic cylinder end surface, and a through-hole is obstruct | occluded with solder, there is no organic substance inside. Therefore, it is possible to stretch the wire without slacking in a state where tension is applied to the wire, and it is unnecessary to use a groove or the like provided on the outer peripheral surface of the conventional cylinder, simplifying the structure, and not including an organic substance inside. A shaped current fuse is obtained.

  The above manufacturing process is premised on production automation. First, the formation of the eyelet-like solder 15 is easy to automate because a solder disk is disposed on the end face of the ceramic cylinder 11 and is removed by a jig (punch). Next, in the wire passing step of passing the fusible wire through the ceramic cylinder, the fusible wire 16 covered with the wire guide 21 is inserted into the ceramic cylinder, only the wire guide 21 is pulled out, and both ends of the wire are chucked 25 , 26 for temporary holding. Next, the wire stretching process of slanting the wire into the ceramic cylinder can be performed in one operation by holding the ceramic cylinder 11 with the gripping portions 24a and 24b of the rotary jig 24 and rotating the rotary jig 24 by 90 degrees. .

  In the wire bonding step of fixing and cutting the wire to the end of the ceramic cylinder, the wire 16 is heated by the heater chip while applying the tension tension F to the wire 16, so that the wire is loosened by melting the solder while maintaining the tension. The wire can be cut at the end face of the cylinder by breaking by applying a tension Fa by applying tension T Fa. Therefore, according to the manufacturing process, the fuse can be mass-produced with high productivity.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

  The present invention can be used for manufacturing a cylindrical current fuse suitable for surface mounting.

Claims (5)

A solder forming step of attaching solder to an opening communicating with the through hole of the ceramic cylindrical body provided with the through hole;
A wire passing step of passing a wire that is a soluble material into the through hole of the ceramic cylinder;
A wire stretching step in which the end of the wire passed through the ceramic cylinder is gripped by a chuck, and the wire is slanted into the through hole in a state where a predetermined tension is applied;
A wire bonding step of fixing the wire to the opening of the ceramic cylinder via the solder and cutting the wire,
In the wire bonding process, the wire is brought into contact with the opening of the ceramic cylinder, the contact portion of the wire is heated , fixed to the opening of the ceramic cylinder via solder, and tension is applied to apply the wire. A method of manufacturing a cylindrical current fuse, characterized by breaking . The wire bonding process includes bonding of the primary side of the wire and bonding of the secondary side of the wire,
Bonding the primary side of the wire is performed by applying tension with chucks on both sides of the wire while the tip of the heater chip directly touches the wire and fixes the primary side of the wire to the opening of the ceramic cylinder via solder. The wire breaks by applying a force larger than the tension from the primary side chuck,
The secondary side of the wire is joined by heating the solder so that the tip of the heater chip does not directly touch the wire, and applying the tension with the secondary side chuck of the wire while the secondary side of the wire is connected to the ceramic cylinder. 2. The cylindrical current fuse according to claim 1, wherein the wire breaks by being fixed to another opening via solder and applying a force larger than the tension from the secondary chuck of the wire. Method.   3. The cylindrical current according to claim 1, wherein the wire cutting in the wire joining step is performed by applying a tension to the wire in a direction having an angle from a creeping end surface of the ceramic cylindrical body toward the cylindrical body. Fuse manufacturing method.   The wire passing step inserts a wire covered with a wire guide, holds the wire tip, then pulls out the wire guide, holds the other end of the wire, and then cuts the wire A method for manufacturing a cylindrical current fuse according to any one of claims 1 to 3.   5. The method of manufacturing a cylindrical current fuse according to claim 1, wherein in the wire stretching step, the wire is slanted by rotating the ceramic cylinder.

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