JP2005224840A - Solder feeding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solder feeding apparatus improved in such a manner that the scattering of the microparticles of the residue in solder to a workshop and the red-hotting of solder can be effectively prevented in a soldering stage, to provide an impeller shaft mounted thereon, and to provide a soldering device provided with the solder feeding apparatus. <P>SOLUTION: In the solder feeding apparatus where molten solder is fed to a blowing port 14 of a solder blowing port tower by the rotation of an impeller shaft 3 in a soldering tank 10, at least the part contacted with the surface part of the molten solder in the impeller shaft has an outer shape capable of disturbing the molten solder on the circumference thereof at the operation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a solder feeding device used for a jet-type soldering device. More specifically, the solder feeding device improved so as to effectively prevent the fine particles of solder casks from being diffused into the work place and the red heat of the molten solder in the soldering process, and the impeller shaft equipped therein Further, the present invention relates to a soldering apparatus in which the deterioration of the working environment in the soldering work is reduced by providing such a solder feeding apparatus.

Conventionally, jet-type soldering devices have been used in automatic soldering of printed circuit boards and the like. For example, a jet-type soldering device 15 as shown in FIG. 5 is usually provided with a motor 5 as a driving device for feeding the molten solder 6 accommodated in the solder tank 10 to the nozzle 14 of the solder nozzle tower 12. An impeller shaft 16 attached thereto and a solder feeding device 17 including the impeller 4 are provided. The molten solder 6 is supplied to the solder nozzle tower 12 by the rotation of the impeller 4, and is ejected as a primary jet or a secondary jet from the solder nozzle tower 12 through the nozzle 14 and adheres to the printed circuit board 13. Soldering is done.
However, when the conventional solder feeding apparatus as described above is used, there are problems to be improved as described below.
The first is the scattering of the fine particles into the working chamber, which is assumed to be caused by the formation of solder casks. In other words, particularly when soldering using lead-free solder, since the molten solder is hotter than conventional solder, its surface is an oxide generated by oxygen in the air. Solder casks are formed. When the impeller shaft 16 rotates, a vortex flow is formed on the surface of the molten solder around the impeller shaft 16, and a phenomenon occurs in which the solder cusps existing on the surface are attracted one after another to the vicinity of the impeller shaft 16. Thereafter, as shown in FIG. 6 (a), in the vicinity of the surface of the molten solder 6 of the impeller shaft 16, minute particles 18 are formed due to the contact between the collected solder residue and the impeller shaft 16, and scattered in the work place. End up. It is not preferable from the viewpoint of hygiene that the fine particles of solder casks are scattered and floated in the air.
Secondly, at the contact portion between the impeller shaft 16 and the surface portion of the molten solder 6, a red heat 19 is generated, as shown in FIG. The red heat 19 may disperse sparks depending on the situation of the field such as the flow of air. If left untreated, it may cause ignition or ignition of other industrial raw materials, which may lead to a fire in the workplace. Therefore, it has been desired to prevent the generation of solder cusp fine particles and the generation of red hot solder.
Therefore, conventionally, as shown in FIG. 7, the periphery of the impeller shaft 16 provided in the solder feeding device 17 is covered with a metal cylindrical member 20 coated with Teflon (registered trademark), so that the fine particles of the solder residue are formed. Attempts have been made to solve the problems of generation and excessive heat generation of solder. One example of this type is a jet-type soldering device described in Japanese Patent Application Laid-Open No. 2000-114708. The publication relates to an embodiment in which a cylindrical member is interposed while maintaining a certain clearance around the impeller shaft, and the cylindrical member blocks contact with air and oxidizes the surface of the molten solder around the impeller shaft. Therefore, it was intended to prevent the generation of solder residue around the impeller shaft and the spread to the entire solder tank. The present inventor has also tried a method of covering the periphery of the impeller shaft 16 with a foamed polystyrene cylinder.

JP 2000-114708 A

However, the method of covering the contact surface portion of the impeller shaft with the molten solder with some member can substantially prevent generation of fine particles of the solder residue, but can solve the problem of red heat due to excessive heat generation of the solder. There wasn't. That is, during operation, the red-hot phenomenon due to the heat generated by the solder is not noticeable on the surface portion of the molten solder 6, but if the cylindrical member 20 is removed by maintenance work, it is hidden in the deep layer portion of the molten solder 6 that cannot be seen from above. The red-heated solder that had progressed to the surface floats on the surface from below. After all, the method of covering the impeller shaft does not solve the fundamental problem. Furthermore, since the structure in which the periphery of the impeller shaft 6 is covered with the cylindrical member 20 tends to be complicated, attachment, removal, or cleaning work tends to be complicated, which is disadvantageous in terms of work efficiency. Met.
As described above, reddening due to excessive heat generation of solder, and prevention of generation of sparks by it, still remained as problems to be solved by those skilled in the art.

The inventor has conducted extensive research on the above problems. As a result, when the impeller shaft rotates, the impeller shaft is equipped with an impeller shaft in which the structure in contact with the vicinity of the surface of the molten solder can disturb the surrounding molten solder. Surprisingly, by using a solder feeding device, it was found for the first time that not only the generation of fine particles of solder casks but also red heat due to excessive heat generation of solder can be effectively prevented, and the present invention has been completed. is there.
Specifically, the present invention relates to a solder feeding device that feeds molten solder to a nozzle of a solder nozzle tower by rotation of an impeller shaft in a solder tank, and at least a surface portion of molten solder of the impeller shaft. The part in contact with the solder feeding device according to the present invention has an outer shape capable of disturbing the molten solder around it during operation.
One of such solder feeding devices is an aspect in which the impeller shaft has a non-circular cross section at least at a portion in contact with the surface portion of the molten solder.
Specifically, in the aspect, first, the above-described impeller shaft has a convex portion attached to the circle by joining the convex strip portion at least at a portion that contacts the surface portion of the molten solder. The present invention relates to a solder feeding device having a cross section in shape.
Secondly, the impeller shaft described above has a shape in which a part of a circle is cut out by cutting away at least a portion that contacts the surface portion of the molten solder, specifically, a substantially D-shaped cross section. The present invention relates to a solder feeding device.
Thirdly, the impeller shaft described above has a transverse cross section having a polygonal shape such as a pentagon, a hexagon, or the like or a cross section close to at least a portion contacting the surface portion of the molten solder. Related.
Another aspect of the present invention is characterized in that the impeller shaft has a cross section in which the center of gravity of the cross sectional figure deviates from the center of rotation of the impeller shaft at least at a portion in contact with the surface portion of the molten solder. It also relates to a solder feeding device.
Specifically, this other aspect is that the impeller shaft described above has an eccentric circular cross section, or an elliptical cross section or a cross section having a shape close to that of at least a portion in contact with the surface portion of the molten solder. The present invention relates to a characteristic solder feeding device.
Furthermore, the present invention relates to the above-described impeller shaft provided in the solder feeding device.
Furthermore, the present invention also relates to a soldering device provided with the above-described solder feeding device.
In this specification, “scratching” means that a turbulent flow is generated or undulated in the surrounding molten solder when the impeller shaft rotates, and the generation of oxide of the molten solder is further suppressed. “Scratching” in such an embodiment is more preferable.
Although the mechanism by which the red heat of the solder is suppressed is not well understood by the present invention, it is inferred as follows. The conventional impeller shaft is a cylindrical member, and when rotating around its axis, the trajectory drawn by the shaft peripheral surface is a completely circular trajectory. Therefore, at the contact surface between the rotating impeller shaft and the solder cusps that have gathered around it, the solder cus in the same part always contacts the impeller shaft continuously, and the solder cus is heated abnormally by the frictional heat generated there. It becomes red hot. On the other hand, in the impeller shaft of the present invention, the peripheral molten solder is continuously disturbed during rotation, so that the solder cusps gathered near the impeller shaft are always in constant contact with the shaft peripheral surface. Therefore, abnormal accumulation of frictional heat does not occur on the contact surface. Therefore, reddening is suppressed.

In the solder feeding device of the present invention, at least a portion of the impeller shaft that is in contact with the surface portion of the molten solder has an outer shape that can disturb the surrounding molten solder during operation. For this reason, it is possible to prevent the contact surface with the surrounding molten solder from being always the same, and to effectively generate red particles due to the generation of fine solder particles on the surface of the molten solder and below, and excessive heat generation of the solder. Can be prevented.
Further, the impeller shaft according to the present invention that can disturb the surrounding molten solder at the time of rotation is merely a non-circular cross section, that is, as an example, a shape in which a convex portion is attached to a circle by joining convex portions. Or a cross-section of a shape obtained by partially cutting off a part of a circle, for example, a substantially D-shaped cross-section, or a cross-section of a polygon or a shape close thereto. Therefore, since the structure is relatively simple, it does not require a complicated formwork, can be easily produced from a conventional round shaft impeller shaft, and also can be removed and cleaned. Easy.
Further, in the solder feeding device according to the present invention, the impeller shaft has a cross section in which the center of gravity of the cross sectional figure deviates from the center of rotation of the impeller shaft at least at a portion in contact with the surface portion of the molten solder. In this way, it is possible to disturb the surrounding molten solder during operation, and it is possible to effectively prevent the generation of fine solder particles, red heat of the solder, and generation of sparks.
Further, the soldering device provided with the solder feeding device having the impeller shaft according to the present invention can effectively prevent generation of fine particles of solder casks and scattering into the work place, redness of solder and scattering of sparks. Therefore, it also has the advantage that the working environment in soldering is improved.

  In the solder feeding device of the present invention, in order to prevent the impeller shaft to be equipped and the contact surface of the molten solder from being always the same, the impeller shaft has at least a portion in contact with the surface portion of the molten solder. It is sufficient to use an embodiment having an external shape capable of disturbing the molten solder around it during operation.

As one aspect thereof, a solder feeding device 2 provided in the soldering device 1 shown in FIG. 1 can be cited. The solder feeding device 2 includes an impeller shaft 3, an impeller 4, and a motor 5 for driving the impeller shaft 3. The impeller shaft 3 is substantially D-shaped as shown in FIG. 2 (a) which is an enlarged view of the V portion in FIG. 1 and FIGS. 2 (b) and 2 (c) showing cross-sectional views taken along line AA. Having a transverse cross section. When the impeller shaft 3 is rotated in the melting solder 6 in the counterclockwise direction with the rotation center as X (in the direction of the arrow in the figure), a trajectory as shown by a solid line and a broken line in FIG. The impeller shaft 3 can disturb the molten solder 6 around the impeller shaft 3 by drawing this trajectory at the time of rotation, so that the contact surface with the molten solder 6 can always be changed during the rotation. The present inventor installed such an impeller shaft 3 in the solder feeding device 2 and assembled the soldering device 1 and soldered, and as a result, the generation of fine solder particles and the prevention of excessive heat generation of the solder were performed. It has been confirmed that it has a great effect. In addition to the substantially D-shape, it has been found that the impeller shaft has the same effect as long as the cross section of the impeller shaft is a semi-circular shape or a sector shape that is partially cut and has a part of the circle cut away.

  Further, in the solder feeding device of the present invention, as another embodiment of the cross-sectional shape of the impeller shaft that may have an effect of disturbing the surrounding molten solder, for example, FIG. 3A and a cross-sectional view taken along line BB of FIG. As shown in FIG. 3B and FIG. 3C, the impeller shaft 8 having a cross section in which a convex portion is attached to a circle can be given by joining the convex portion 7. . When the impeller shaft 8 is rotated counterclockwise with the Y shown in FIGS. 3B and 3C as the center of rotation (in the direction of the arrow in the figure), the impeller shaft 8 is indicated by a solid line and a broken line in FIG. Draw a trajectory. That is, the ridge portion 7 functions to disturb the surrounding molten solder 6. The protruding line portion only needs to protrude outward in a circular shape, and examples thereof include protruding lines having a semicircular cross section, a triangular cross section, and a trapezoidal cross section.

  Thus, if the impeller shaft equipped in this is a non-circular cross section, the solder feeder of this invention has the effect of disturbing the surrounding molten solder at the time of rotation of the impeller shaft. Other non-circular cross-sectional shapes that exhibit similar effects include, for example, polygons such as pentagons and hexagons, or shapes close thereto.

Furthermore, in the present invention, even if the cross-sectional shape of the impeller shaft used is circular as in the prior art, it is possible to disturb the surrounding molten solder during rotation. This can be achieved by using a cross-sectional shape in which the center of gravity of the cross-sectional figure of the impeller shaft is located away from the center of rotation of the impeller shaft. One example is an impeller shaft 9 having an eccentric circular cross section as shown in FIG. 4A and a cross-sectional view taken along the line CC in FIG. 4B and FIG. 4C. The center of gravity Z ′ of the circular section of the impeller shaft 9 having a circular cross section is shifted from the rotation center Z to an arbitrary position, that is, decentered, and then rotated counterclockwise (in the direction of the arrow in the figure). . Then, the impeller shaft 9 draws the surrounding molten solder 6 by drawing a trajectory that pushes the surrounding molten solder outward from the rotation center Z, as shown by the solid and broken lines in FIG. Effectively disturb.
As another aspect of the impeller shaft having a cross section in which the center of gravity of the cross-sectional figure deviates from the center of rotation of the impeller shaft, for example, one having a cross section such as an elliptical shape or a shape close thereto can be used. .

  The impeller shaft of the solder feeding device of the present invention may have any cross-sectional shape as long as it can disturb the surrounding molten solder, but the molten solder is prevented from being oxidized as much as possible when the impeller shaft rotates. It should be selected that the molten solder does not scatter significantly out of the solder bath and that is easy to manufacture in terms of production efficiency.

  The present invention will be described in more detail with reference to the drawings. The following examples are not intended to limit the invention.

Example 1
In this embodiment, a soldering device 1 is prepared in which a solder feeder 2 equipped with an impeller shaft 3 having a substantially D-shaped cross section shown in FIGS. 2 (a), 2 (b) and 2 (c) is used. did. The soldering apparatus 1 includes a solder tank 10 made of cast iron filled with lead-free solder as the molten solder 6, a heater 11 for heating and maintaining the solder at a constant temperature, and the molten solder 6 supplied by the solder feeding apparatus 2. A solder spout tower 12 is provided. Further, at the upper part of the solder nozzle tower 12, a solder nozzle 14 is provided for the molten solder 6 to jet out and adhere to the printed circuit board 13.
Next, in the soldering apparatus 1, the motor 5 is driven to continuously rotate the impeller shaft 3 at 3000 rpm, and after 7 hours, the impeller shaft 3 and the molten solder 6 are rotated.
The test of observing the contact portion of the molten solder 6, particularly the contact portion in the surface portion of the molten solder 6 was performed. As a result, there was almost no generation of fine solder particles at the contact portion in the surface portion, and only large particles were observed. Moreover, no redness of the solder was observed at such contact sites. Further, the impeller shaft 3 was removed from the molten solder 6 and the surface layer of the molten solder 6 was removed. However, the red hot solder did not emerge from below the surface layer.

Example 2
In this embodiment, the assembly is performed by using a solder feeding device equipped with an impeller shaft 8 having a cross section of a shape in which a convex portion is attached to a circle, as shown in FIGS. 3 (a), (b) and (c). A soldering device was prepared. In addition, the soldering apparatus in a present Example is the structure similar to the soldering apparatus 1 used in Example 1 except the impeller shaft 8. FIG.
Next, the same test as in Example 1 was performed. As a result, as in the result in Example 1, no fine solder particles were generated, and no solder redness was observed.

Example 3
In this embodiment, there is prepared a soldering device using a solder feeding device equipped with an impeller shaft 9 having an eccentric circular cross section shown in FIGS. 4 (a), (b) and (c). did. In addition, the soldering apparatus in a present Example is the structure similar to the soldering apparatus 1 used in Example 1 except the impeller shaft 9. FIG.
Next, the impeller shaft 9 is continuously rotated at 3000 rotations / minute with one position Z, which is substantially in the middle between the center of gravity Z ′ of the cross-sectional circle and the circumference, and then Example 1 Observed in the same manner. As a result, similar to the result in Example 1, there was no generation of fine solder casks, and no solder redness was observed.

It is a longitudinal cross-sectional view which shows the soldering apparatus 1 with which the solder feeding apparatus 2 equipped with the impeller shaft 3 of this invention was provided. (A) is an enlarged view of the V part of the solder feeder 2 of the present invention, (b) is a cross-sectional view taken along the line AA of (a), and (c) is a view of the impeller shaft 3 during rotation. It is a schematic diagram which shows an orbit. (A) is the enlarged view of the impeller shaft 8 of this invention, (b) is sectional drawing in the BB line of (a), (c) is the track | orbit of the impeller shaft 8 of this invention at the time of rotation. It is a schematic diagram shown. (A) is the enlarged view of the impeller shaft 9 of this invention, (b) is sectional drawing in CC line of (a), (c) of this invention when rotating centering on Z as a rotation center. FIG. 3 is a schematic diagram showing a track of an impeller shaft 9. It is a longitudinal cross-sectional view which shows the soldering apparatus 15 with which the conventional solder feeding apparatus 17 was provided. (A) is a schematic diagram showing generation of solder fine particles around the conventional impeller shaft 16, and (b) is a schematic diagram showing solder reddening around the conventional impeller shaft 16. It is the figure which showed the conventional impeller shaft 16 covered with the cylindrical member 20, and the soldering apparatus with which this was equipped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Soldering apparatus of this invention 2 Solder feeding apparatus of this invention 3, 8, 9 Impeller shaft of this invention 4 Impeller 5 Motor 6 Molten solder 7 Convex part 10 Solder tank 11 Heater 12 Solder outlet tower 13 Printed circuit board 14 Spout 15 Conventional soldering device 16 Conventional impeller shaft 17 Conventional solder feeding device 18 Solder residue microparticles 19 Red-hot solder 20 Cylindrical member

Claims (11)

In the solder feeding device for feeding molten solder to the nozzle of the solder nozzle tower by the rotation of the impeller shaft in the solder tank,
A portion of the impeller shaft that comes into contact with at least a surface portion of the molten solder has an outer shape capable of disturbing the surrounding molten solder during operation. The solder feeding device according to claim 1, wherein the impeller shaft has a non-circular cross section at least at a portion contacting the surface portion of the molten solder. The said impeller shaft has a cross section of the shape where the convex part was attached to the circle | round | yen by joining a convex strip part about the site | part which contacts the surface part of a molten solder at least. Solder feeding device. 3. The solder supply according to claim 2, wherein the impeller shaft has a cross-section having a shape in which a part of a circle is cut out by partially cutting at least a portion contacting the surface portion of the molten solder. Feeding device. 5. The solder feeding device according to claim 4, wherein the impeller shaft has a substantially D-shaped cross section at least at a portion in contact with the surface portion of the molten solder. The solder feeding device according to claim 2, wherein the impeller shaft has a cross section of a polygonal shape or a shape close to the polygonal shape at least at a portion in contact with the surface portion of the molten solder. 2. The solder feeding device according to claim 1, wherein the impeller shaft has a cross section in which a center of gravity of a cross-sectional figure deviates from a rotation center of the impeller shaft at least at a portion contacting the surface portion of the molten solder. . The solder feeding device according to claim 7, wherein the impeller shaft has an eccentric circular cross section at least at a portion in contact with the surface portion of the molten solder. The solder feeding device according to claim 7, wherein the impeller shaft has an elliptical shape or a cross-section having a shape close to that of at least a portion contacting the surface portion of the molten solder. The impeller shaft according to any one of claims 1 to 9, which is provided in the solder feeding device. A soldering apparatus provided with the solder feeding apparatus according to claim 1.

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