JPH04123415A - Manufacture of capacitor - Google Patents

Abstract

PURPOSE:To manufacture a capacitor having excellent characteristics of less dispersion by pressing a capacitor element with a specified pressure applied to its pressing face in the process to mold the wound capacitor element into an elliptical form. CONSTITUTION:Raising pressure on a pressing face above 600kg/cm<2> with a capacitor element 2 gripped from above and below by press plates 1 forces the pressed capacitor element 2 to keep an elliptical shape as it is even upon release of pressure. The electrostatic capacitance of the capacitor element 2 increases with rises in pressure. When pressure on the pressing face 3 is further raised to exceed 900kg/cm<2>, an edge 4 of the pressed capacitor element 2 comes bent with the result that its tan delta characteristics generate dispersion. This way of pressing the capacitor element 2 under a pressure of 600-900kg/cm<2> by gripping with the press plates 1 allows manufacture of capacitors having stable characteristics of less dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to capacitors for electric circuits used for power factor improvement such as power capacitors and capacitors for electrical equipment, motor drives, and various power supply circuits. Regarding the manufacturing method.

Conventional technology In the conventional manufacturing method of oval-shaped capacitors, in order to form a wound capacitor element into an oval shape, the capacitor film itself is formed into an oval shape by heat treatment using thermal expansion and mechanical pressure. was common. In particular, AC capacitors require the above steps to stabilize their electrical characteristics.

FIG. 5 shows a part of the conventional capacitor manufacturing method, and as shown in the figure, the capacitor element 6 is placed between the partition plate 7
After stacking several layers, the capacitor element 6 is pressed into an oval shape, and in this state, the partition plate 7 is fixed by a method such as a frame. Thereafter, the capacitor element 6 heated in the heat treatment process is formed into an oval shape by the thermal expansion of the film itself and mechanical pressure by the partition plate 7 fixed by a method such as a frame.

Another conventional method for forming the capacitor element 6 into an oval shape is to press the capacitor element 6 while heating it with a press plate 9 having a built-in heater 8, as shown in FIG. In this method, mechanical pressure is applied to the capacitor element 6 by pressing, and at the same time, heat from a press plate 9 heated by a heater 8 is applied to the capacitor element 6 to thermally expand the film of the capacitor element 6. is formed into an oval shape.

Problems to be Solved by the Invention However, in the conventional manufacturing method of oval-shaped capacitors, as shown in FIG.
This requires a process of fixing the frame in a pressed state. Once, after metallicon and heat treatment,
A process of removing the capacitor element 6 from the frame is also necessary,
There was a problem in that the manufacturing method was extremely complicated, such as the process of removing metallicon adhering to the framework and partition plate 6 during the metallicon manufacturing process.

In addition, as shown in FIG. 6, in other conventional examples, it takes a long time for the heat of the press plate 9 with the heater 8 therein to be transmitted to the inside of the capacitor element 6, especially when the shape of the capacitor element 6 is The larger it is, the longer it takes for heat to reach its interior. Therefore, there is a difference in the effect of heat treatment due to thermal expansion of the film between the outer periphery of the capacitor element 6, where the heat of the press plate 9 is easily transferred, and the inside, where the heat is not easily transferred. Is it possible to shorten the heat transfer time to the inside of the capacitor element 6 to some extent by increasing the temperature of the press plate 9?Since the capacitor film that constitutes the capacitor element 6 has a limit in temperature characteristics, the capacitor element It is difficult to significantly shorten the heat conduction time (1).

The present invention is intended to solve the above problems, and aims to provide a method that allows manufacturing capacitors with excellent characteristics with little variation through extremely simple steps.

Means for Solving the Problems In order to achieve the above object, the present invention applies a pressure of 600 to 900 kg/d to the pressing surface of the capacitor element in the process of forming a wound capacitor element into an oval shape. It was designed to do so.

According to the present invention, by applying pressure that exceeds the elastic limit of the wound capacitor film constituting the capacitor element, it is possible to sufficiently maintain the oval shape of the capacitor element. By applying heat treatment to stabilize the physical characteristics, a capacitor with extremely stable characteristics with little variation can be obtained.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 (al is a schematic front view showing the pressing step in the method for manufacturing a capacitor according to an embodiment of the present invention, FIG. 1 fbl is a perspective view of the capacitor element showing the area to which pressure is applied in the pressing step, FIG. 2 is a characteristic diagram showing the relationship between press pressure and capacitance of the oval capacitor manufactured according to this example, and the press pressure represented by the horizontal axis is the press surface of the diagonally shaded part of the capacitor element shown in FIG. It is for.

Next, the main points of the manufacturing method of this example will be explained.

In order to form the wound capacitor element into an oval shape, as shown in FIG. The pressure on the press surface 3 of the shaded part of the capacitor element 2 shown in Figure 1 (bl) is 600
If it is less than kg/cm, the capacitor element 2 pressed into an oval shape or its film tends to return to its round shape due to the elastic force of the film. However, if the pressure on the pressing surface 3 is increased to 600 kg/cut or more, the pressed capacitor element 2 will maintain its oval shape even after the pressure is removed. Furthermore, as shown in FIG. 2, the capacitance of the capacitor element 2 also increases as the press pressure increases. As is clear from Fig. 2, in order to obtain a capacitance equal to or higher than the capacitance of a capacitor produced by the conventional manufacturing method, it is necessary to Requires press pressure.

Next, the press pressure on the press surface 3 is further increased, and when it exceeds 9.00 kg/af, the film end 4 is bent, as shown in FIG. The song is f: state (!: f,
; In this state, when the film edge surface 5i metallicon (not shown) is applied, the film is not filled.

The contact between the end face 5 and the metallicon is caused by the bent film 4, which causes a problem, resulting in variations in the tan δ characteristics as shown in the characteristic diagram C in FIG. In order to eliminate this C variation, it is necessary to set the press pressure to 900klad or less.

In this way, according to the above embodiment, by sandwiching the capacitor element 2 between the press plates 1 and pressing it at a pressure of 600 to 900 kg/a, a capacitor having stable characteristics with little variation can be manufactured. .

Effects of the Invention As is clear from the above embodiments, the present invention provides a wound capacitor element with an angle of 600 to 900/c to its pressed surface.
d pressure, and as a result, it is possible to eliminate the conventional framework process using partition plates, frame removal process, etc., and therefore the manufacturing process can be simplified. In addition, even during the process of heat treatment to stabilize the electrical characteristics, the capacitor element sufficiently maintains its oval shape, so it receives the full effect of the heat treatment, making it possible to manufacture capacitors with stable electrical characteristics. I can listen.

In addition, since heat is not applied directly to the capacitor element from the press plate, the outer periphery of the capacitor element and It is possible to eliminate the influence on the heat treatment effect due to the difference in thermal expansion of the film itself inside, and to eliminate variations in characteristics due to the size of the capacitor element.

[Brief explanation of drawings]

Figure 1 (al is a front view of the main part showing the pressing step in the capacitor manufacturing method of one embodiment of the present invention, Figure 1 fbl
is a perspective view of a capacitor element showing the area to which pressure is applied in the same pressing process, Figure 2 is a characteristic diagram showing the relationship between pressing pressure and capacitance of the capacitor manufactured by the same example, and Figure 3 is a diagram of the capacitor element. FIG. 4 is a cross-sectional view of a main part showing the state of the end face of the film when excessive pressure is applied to the capacitor, and FIG. , FIG. 5 is a front view of a main part showing a pressing process in a conventional capacitor manufacturing method, and FIG. 6 is a sectional view of a main part showing a pressing process in another conventional example. 1...Press plate, 2...Capacitor element, 3...Press surface. Name of agent: Patent attorney Haruaki Ogata and 2 others

Claims (1)

[Claims] A method for manufacturing a capacitor, which comprises sandwiching a wound capacitor element between press plates, applying a pressure of 600 to 900 kg/cm^2 to the press plates to press the capacitor element, and forming it into an oval shape.