JP2006147703A - Tab terminal for electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tab terminal for electrolytic capacitors that can wind electrode foil with high density without cracking the electrode foil even if the electrode foil is wound with high tension. <P>SOLUTION: In the tab terminal for electrolytic capacitors comprising a round rod, a rolled section in which the round rod is machined flatly, and a leading line welded to the round rod; four corners are chamfered on the rectangular section of the rolled section. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tab terminal for an electrolytic capacitor. More specifically, the present invention relates to a tab terminal for an electrolytic capacitor, in which the electrode foil is not damaged even when the electrode foil is wound with high tension, and the electrode foil can be wound with high density.

  The aluminum electrolytic capacitor has a structure in which a driving electrolytic solution is impregnated into a capacitor element in which an aluminum anode foil and an aluminum cathode foil are wound around a tab terminal via a separator, and the element is embedded in an outer case and sealed. . Moreover, the tab terminal is comprised from the round bar part which consists of aluminum, the rolling part which processed this round bar part in flat shape, and the leader line welded to the round bar part.

  In recent years, the development of miniaturized and large-capacity aluminum electrolytic capacitors has been promoted. For example, the electrostatic capacity is improved by increasing the number of turns using an ultrathin electrode foil or by increasing the effective surface area by etching the electrode foil electrode foil.

  Moreover, when winding electrode foil around a tab terminal, it is performed to make a high-density capacitor element by winding it while applying high tension to the electrode foil.

  Furthermore, a capacitor element close to a perfect circle that can be efficiently housed in the outer case by devising the shape of the winding shaft when the electrode foil starts to be wound around the tab terminal has been proposed.

  However, since the rolling part of the conventional tab terminal was formed into a flat plate shape by pressing, the electrode foil contacts the side surface of the rolling part when the electrode foil is wound around the rolling part, and the electrode foil is damaged. was there. In particular, in a miniaturized aluminum electrolytic capacitor, since the product diameter is small, the winding curvature of the element is increased, and the contact pressure between the rolled portion and the electrode foil is increased, so that the electrode foil is easily damaged.

  Further, when the electrode foil is wound with high tension, the contact pressure between the rolled portion and the electrode foil is naturally increased, and the electrode foil is easily damaged.

  In response to such a problem, in the previous application (Japanese Patent Application No. 2002-151344), the inventors defined the corners of the four corners of the rolled portion, which is the portion where the rolled portion of the tab terminal is in contact with the aluminum foil, as the round shape. By doing so, it is proposed that the contact pressure between the aluminum foil and the rolled part is lowered to prevent the electrode foil from being damaged.

  However, even when the cross-sectional end portion is a rolled portion having a round shape, the cross-sectional end portion of the rolled portion remains in contact with the electrode foil more than the surface of the rolled portion. There is still a need for a tab terminal that can be wound at a high density without damaging the wire.

  The inventors of the present invention pay attention to the fact that when the electrode foil is wound around the flat rolled portion, gaps are always generated in the vicinity of the rolled portion, and there is a limit to winding the electrode foil at a high density. By processing the four corners of the electrode into a predetermined shape, we obtained the knowledge that even when the electrode foil is wound with high tension, the electrode foil is not damaged and can be wound with high density . The present invention is based on such knowledge.

  Accordingly, an object of the present invention is to provide a tab terminal for an electrolytic capacitor in which the electrode foil is not damaged even when the electrode foil is wound at high tension, and the electrode foil can be wound at a high density. To do.

  An electrolytic capacitor tab terminal according to the present invention is an electrolytic capacitor tab terminal comprising a round bar portion, a rolled portion obtained by processing the round bar portion into a flat shape, and a lead wire welded to the round bar portion, Chamfering is performed on the four corners of the rectangular cross section of the rolled portion. Thus, by chamfering the four corners of the cross section of the rolled part, even when the electrode foil is wound around the rolled part, the contact between the end of the rolled part and the aluminum foil is reduced, so the electrode foil is damaged. Nothing will happen.

  Also, by chamfering the four corners of the cross section of the rolled part, the gap in the vicinity of the rolled part in the state where the electrode foil is wound is reduced as compared with the conventional flat rolled part, so that the electrode is denser. The foil can be wound. As a result, the element volume efficiency of the capacitor element is improved.

  The tab terminal for electrolytic capacitors according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the tab terminal for an electrolytic capacitor of the present invention includes a round bar portion 1, a rolled portion 2 obtained by processing the round bar portion into a flat shape, and a lead wire 3 welded to the round bar portion 1. It consists of As a material constituting the round bar portion and the rolled portion, aluminum or the like is usually used. In addition, as the lead wire, an iron wire, a copper wire, or an iron wire coated with copper (CP wire) or the like is used. The lead wire is usually solder-plated on the surface in order to improve soldering characteristics.

  FIG. 2 shows an A-A ′ cross section of the rolled portion 2 of the tab terminal shown in FIG. 1. The tab terminal for an electrolytic capacitor of the present invention has a shape in which chamfering is performed at four corners of a rectangular cross section of a rolled portion. By applying chamfering 6 to the four corners of the rectangular cross section of the rolled portion, that is, the portion where the rolling surface 4 and the side surface 5 of the rolled portion are in contact, the contact pressure between the end of the rolled portion and the electrode foil can be reduced. Therefore, even when the electrode foil is wound with high tension, the electrode foil is not stressed and is not damaged. Moreover, compared with the tab terminal which has the rolling part of the conventional rectangular cross section, the space | gap of the electrode foil formed in the rolling part vicinity decreases. As a result, the element volume efficiency of the capacitor element is improved. Therefore, when an aluminum electrolytic capacitor having the same volume is produced, the electrode foil can be wound at a higher density when the rolled portion is curved.

  Furthermore, the aluminum electrolytic capacitor of the present invention is very excellent in quality stability. Although it is not certain as a reason for having such an unexpected effect, it is considered that the contact area between the surface of the tab terminal rolled portion and the aluminum foil increases.

  In the tab terminal for electrolytic capacitors of the present invention, the chamfered surface 6 preferably has an angle of 150 to 173 degrees with respect to the rolling surface 4 of the rolled portion, and is 152 to 170 degrees. Is more preferable. By giving the chamfered surface an angle in such a range, it is possible to improve the element volume efficiency of the electrolytic capacitor while preventing the electrode foil from being damaged, and to easily manufacture a tab terminal having such a shape. can do. That is, when the chamfered surface 6 is less than 150 degrees with respect to the rolled surface 4 of the rolled part, there is a possibility that punch chipping may occur when the rolled part is formed by press working. In addition, the effect of chamfering cannot be expected at 173 degrees or more. Here, the angle of the chamfered surface with respect to the rolled surface of the rolled portion means an angle θ at the point where the rolled surface 4 of the tab terminal rolled portion and the chamfered surface 6 are in contact with each other, as shown in FIG.

  Moreover, as shown in FIG. 2, when the length of the rolling surface is L and the width is W, the length (L ′) of the flat portion of the rolling surface is 0.50L to 0.95L, and the rolled part The length (W ′) of the flat portion on the side surface is preferably 0.03 W to 0.80 W, L ′ is 0.65 L to 0.90 L, and W ′ is 0.3 W to 0.70 W. Is more preferable. By performing the length of the flat part of the rolling surface and the length of the flat part of the side surface of the rolling part within the above range, that is, the degree of chamfering processing within the above range, the electrolytic capacitor is further prevented while preventing the electrode foil from being damaged. The volumetric efficiency of the element can be improved. That is, when the flat part length (L ′) of the rolled part is smaller than 0.50 L, the crimping cannot be sufficiently performed when the electrode foil is crimped to the rolled surface of the tab terminal, and the contact of the element Resistance increases. On the other hand, if L ′ exceeds 0.95 L, the number of windings of the electrode foil can be made only to the conventional level, and the improvement of the capacitance becomes insufficient. Also, if the flat part length (W ′) on the side face of the rolled part is smaller than 0.03 W, the upper and lower mold press punches come into contact with each other when the rolled part is formed by press working, resulting in punch chipping. There is a risk. On the other hand, if W 'is larger than 0.80 W, the number of windings of the electrode foil can be made only to the conventional level, and the improvement of the capacitance becomes insufficient.

  The electrolytic capacitor of the present invention has a shape as shown in FIG. 1 and, as shown in FIG. 3, the rolled part 2 ′ is displaced from the center of the round bar part 1 ′ (eccentric tab terminal). ) Is also present. Such an eccentric tab terminal is mainly used suitably for a small electrolytic capacitor, and when a capacitor element is produced as a pair of tab terminals, the distance between the rolling parts is wider than that of a normal tab terminal. Therefore, the volume element efficiency can be increased.

  In such an eccentric tab terminal, as shown in FIG. 4, different chamfering processes are performed on the rolling surface 4A facing the center side of the capacitor element and the rolling surface 4B facing the outer peripheral side of the capacitor element. It is preferable to apply. Specifically, the flat part length (L '') of the rolled surface on one side of the rolled part is 0.50L to 0.90L, and the flat part length (L '' 'of the rolled surface on the other side. ) Is preferably 0.50L to 0.95L. Since the eccentric tab terminal is used for a small electrolytic capacitor, the curvature radius when the electrode foil is wound around the tab terminal is small. Therefore, since a gap is generated between the rolled portion of the tab terminal and the electrode foil, the volume efficiency of the element is lowered. In the present invention, as shown in FIG. 4, by making L ′ ″ longer than L ″, the electrode foil can be wound with a smaller radius of curvature, thereby increasing the element volume efficiency. A miniaturized electrolytic capacitor can be realized. L ″ is more preferably 0.65L to 0.85L, and L ″ ″ is more preferably 0.70L to 0.90L.

  The rolled part preferably has a thickness (W) of 0.15 to 0.70 mm. Thus, by making the thickness thinner than the conventional rolled portion of the tab terminal, the caulking property of the electrode foil, that is, the electrode foil can be wound around the rolled portion of the tab terminal with high tension. Further, by winding the electrode foil with high tension in this way, the contact resistance between the rolled portion of the tab terminal and the electrode foil is reduced. When the thickness of the rolled part exceeds 70 mm, the caulking property becomes poor. On the other hand, when the thickness is less than 0.15 mm, the strength of the rolled part is reduced, and the rolled part is used when transporting the tab terminal or crimping the electrode foil. Will be damaged.

  Furthermore, in the electrolytic capacitor tab terminal of the present invention, the round shape processing is performed on the boundary portion R1 between the chamfered surface 6 and the rolled portion surface 4 and the boundary portion R2 between the chamfered surface 6 and the rolled portion side surface 5. It is preferable to be applied. As shown in FIG. 5, by making the eight edge portions (R1 to R8) of the cross section of the rolled portion into a round shape, the electrode foil can be further prevented from being damaged. In addition, since the edge portion of the cross section of the rolled portion is rounded as described above, the contact resistance between the edge portion and the electrode foil is reduced, and the high frequency characteristics of the capacitor are further improved. Thus, it was unexpected that contact resistance was reduced by making the edge part round. The reason is not clear, but it is thought as follows. In other words, the charge tends to concentrate on the edge portion of the metal, and it is considered that the charge density becomes uniform by eliminating the edge. Therefore, it is presumed that the leakage current is reduced by making the edge portions (R1 to R8) of the cross section of the rolled portion into a round shape, and as a result, the contact resistance between the terminal and the electrode foil is reduced.

  The radius of curvature of the round shape is preferably 0.01 to 0.85 when the thickness (W) of the rolled portion is 1. By subjecting each edge portion 7 to a round process having such a radius of curvature, the electrode foil is more difficult to break. Further, the contact resistance between the edge portion and the electrode foil is further reduced, and the high frequency characteristics of the capacitor are improved. (Please tell us the significance of setting the radius of curvature to the specified value).

  Next, the manufacturing method of the tab terminal for electrolytic capacitors of this invention is demonstrated.

  FIG. 6 is a front view showing an example of an apparatus for producing the electrolytic capacitor tab terminal of the present invention.

  The cradle 11 is fixed to the foundation 12, and a punch 13 is provided above the cradle 11, and they are arranged so as to face each other.

  A lifting table 15 is provided between the receiving table 11 and the punch 13, and a cutting device 14 is installed on the lifting table 15. The lifting platform 15 is slidably inserted into a support column 16 standing vertically from the foundation 12. The punch 13 is inserted through a vertical through hole 17 provided in the lifting platform 15. The punch 13 moves up and down in conjunction with the punch lift 18, and the punch lift 18 is slidably inserted into the column 6.

  The lower end of the lifting rod 19 is connected to the punch lift 18 and the upper end is connected to a drive source (not shown). Then, the punch 13 is moved up and down together with the punch lift 18.

  The cam 20 is pressed against a roll 22 of a screw rod 21 whose length can be adjusted, and the screw rod 21 is connected to a lifting platform 15, thereby constituting a cutting blade reversing position adjusting mechanism. .

  As shown in the detail view of FIG. 7, the cutting device 14 is configured by integrally assembling a cutting blade 23 and a cutting blade 24 on the left and right sides of the punch 13 and the cradle 11 at positions close to each other.

  The cutting blade 23 is formed with a notch p at its edge, as is more clearly shown in the enlarged view of FIG.

  When the lifting rod 19 is driven and the punch lifting table 18 is lowered, the punch 13 is lowered onto the aluminum head b placed on the cradle 11, and the aluminum head b is crushed and flattened to a predetermined thickness (FIG. 8). ).

  The tip of the punch 13 has a predetermined shape as shown in FIG. 7, and the tip of the cradle 11 also has a predetermined shape corresponding to the tip of the punch 13. Accordingly, the pressed aluminum head (rolled portion) has a shape in which the four corners are chamfered as shown in FIG.

  Next, the cutting device 14 is lowered by the cam 20, and the cutting blade 23 is cut into a portion protruding from the punch 13 and stopped, and a cutting line is cut into the protruding portion (FIG. 9).

  Thereafter, only the cutting device 14 is turned upside down, and simultaneously the cutting blade 23 is moved upward, the lower cutting blade 24 is raised above the tip of the punch 13, and the protruding portion is cut off from the cutting line and cut (see FIG. 10). Blow off the cut aluminum scrap with air.

  Next, the punch 13 is also lifted to open the top of the cradle 11 and take out the tab terminal of the product (FIG. 11).

  By the way, although it is a mutual timing and stroke of the punch 13 and the cutting device 14, in the example of the manufacturing apparatus shown in drawing, this is performed by adjusting the length of the screw rod 21.

  The positional relationship between the punch 13 and the cutting blade 23 whose timing is adjusted in this way is shown in an enlarged manner in FIGS.

  When the punch 13 is lowered and the aluminum head is formed to have a predetermined curved thickness, the cutting blade 23 is then lowered to a state shown in FIGS.

  In FIG. 12, the cutting blade 23 hits the protruding portion and pushes down the protruding portion as shown in FIG. 13, so that the portion sandwiched between the punch 13 and the cradle 11 and the vicinity of the boundary of the protruding portion are pulled.

Subsequently, when the punch 13 is lowered by the depth of the notch portion p of the edge from the position at the beginning of hitting in FIG. 12, the edge of the end of the notch portion p starts to cut into the protruding portion. If you cut deeply and cut deeply, the part that was pulled without cutting until now will be cut off, so that the phenomenon of springback occurs, the part that was pulled back is pulled back to the punch 13 side, and the cutting edge 23 and A gap t is generated between the rolled portions (FIG. 14).

  Because of the gap thus formed, when the cutting edge 23 turns upward, the cutting edge 23 does not catch the peripheral edge of the rolled portion. Therefore, no return burr occurs.

  Here, as shown in FIG. 15, when the inner edge of the punch surface of the punch 13 is formed in the round 25, the edge portions (R1 to R8) of the cross section of the rolled portion of the tab terminal are formed in the same round as shown in FIG. it can.

1. Production of tab terminals Welded a round bar made of aluminum of φ1.5 mm and a CP wire of φ0.6 mm, and using the apparatus shown in FIG. Capacitor tab terminals were prepared. Under the present circumstances, the cross-sectional dimension of the tab terminal rolling part was adjusted by changing the upper and lower punch shape of a manufacturing apparatus.

  In addition, an eccentric type electrolytic capacitor tab terminal was prepared using the same round bar and CP wire as described above. Similarly to the above, the cross-sectional dimension of the rolled portion of the tab terminal was adjusted by changing the shape of the upper and lower punches of the manufacturing apparatus.

The cross-sectional shape of the obtained tab terminal rolling part was as shown in Table 1 below.

2. Evaluation of Tab Terminal (1) Evaluation of Element Volume Efficiency One end of electrode foil / electrolytic paper having a thickness of 100 μm is stitched and fixed to the pair of tab terminals of Examples 1 and 2 and Comparative Example 1 obtained above. And wound to produce a capacitor element. The winding amount of the aluminum foil was set to a limit size (diameter) that can be inserted into an aluminum case (φ10 mm) incorporating the capacitor element.

  In the same manner as described above, one end of a 90 μm-thick electrode foil / electrolytic paper was stitched, fixed, and wound around the pair of tab terminals of Examples 3 and 4 and Comparative Example 2 to produce a capacitor element. The winding amount of the aluminum foil was set to a limit size (diameter) that can be inserted into an aluminum case (φ5 mm) incorporating the capacitor element.

  The cross section of each obtained capacitor element was observed with a magnifying glass, and the ratio of the area of the aluminum foil to the area of the cross section of the aluminum case was calculated.

  The evaluation results were as shown in Table 2 below.

(2) Crack evaluation of electrode foil The cross section of the capacitor element was cut, and the cut surface was observed with a magnifying glass to examine the presence or absence of cracks in the electrode foil generated near the tab terminal. The results were as shown in Table 2 below.

  Moreover, about each capacitor | condenser element produced above, the clearance gap area of the aluminum foil wound around the tab terminal was computed by observing a cross section with a magnifier. As a result, according to the tab terminal of the present invention, the gap area was reduced by about 25% compared to the conventional tab terminals (Comparative Examples 1 and 2). When the tab terminal of the present invention was used, the electrode foil was not damaged even when the electrode foil was wound at a high density, and a high-quality electrolytic capacitor was obtained.

It is a perspective view of the tab terminal of the present invention. It is sectional drawing which showed the A-A 'cross section of the tab terminal of this invention. It is a perspective view of the tab terminal of another aspect of the present invention. It is sectional drawing which showed the B-B 'cross section of the tab terminal shown in FIG. It is sectional drawing which showed the A-A 'cross section of the tab terminal of another aspect of this invention. An example of the apparatus which manufactures the tab terminal of this invention is shown. The manufacturing process of the tab terminal of this invention is shown in order. The manufacturing process of the tab terminal of this invention is shown in order. The manufacturing process of the tab terminal of this invention is shown in order. The manufacturing process of the tab terminal of this invention is shown in order. The manufacturing process of the tab terminal of this invention is shown in order. FIG. 10 is an enlarged view showing the process of FIG. 9 in more detail. FIG. 10 is an enlarged view showing the process of FIG. 9 in more detail. FIG. 10 is an enlarged view showing the process of FIG. 9 in more detail. It is the figure which expanded the punch of the manufacturing apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 'round bar part 2, 2' rolling part 3 Leader 4 Rolling surface 5 Flat part of the side surface of a rolling part 6 Chamfering processing surface 7 R-shaped part 11 Receptacle 13 Punch 14 Cutting apparatus 15 Lifting stand 18 Punch lifting stand 19 Lifting rod 20 Cam 23 Cutting blade 24 Cutting blade b Aluminum head p Notch

Claims (7)

  A tab terminal for an electrolytic capacitor comprising a round bar part, a rolled part obtained by processing the round bar part into a flat shape, and a lead wire welded to the round bar part, and chamfered at four corners of the rectangular cross section of the rolled part Tab terminals for electrolytic capacitors that are processed.   The tab terminal for electrolytic capacitors according to claim 1, wherein the chamfered surface has an angle of 150 to 173 degrees with respect to a rolling surface of the rolled portion.   When the length of the rolling surface of the rolling part is L and the width is W, the length of the flat part of the rolling surface is 0.50L to 0.95L, and the length of the flat part of the side surface of the rolling part is 0. The tab terminal for electrolytic capacitors of Claim 1 or 2 which is 0.03W-0.80W.   The flat part length of the rolling surface on one side of the rolled part is 0.50L to 0.90L, and the flat part length of the rolling surface on the other side is 0.50L to 0.95L. The tab terminal for electrolytic capacitors as described in 3.   The tab terminal for electrolytic capacitors according to claim 3 or 4, wherein a width (W) of a rolled surface of the rolled portion is 0.15 to 0.7 mm.   A boundary portion between the chamfered surface and the rolled portion surface; and The tab terminal for electrolytic capacitors as described in any one of Claims 3-5 by which round shape process is given to the boundary part of the said chamfering surface and the said rolling part side surface.   The tab terminal for an electrolytic capacitor according to any one of claims 3 to 6, wherein the radius of curvature of the round shape is 0.01 to 0.85 when the thickness (W) of the rolled portion is 1. .

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