JPH057999A - Continuous casting machine for pole plate base body for battery - Google Patents

Abstract

PURPOSE:To prevent the development of defect at the time of casting and to facilitate selection of casting condition. CONSTITUTION:A columnar mold 1 having engraving parts 3 corresponding to base body cross section on the outer peripheral surface 2, a molten metal supplying part 4 distributing a molten alloy into the engraving parts 3 and a belt 10 integrally rotating with the columnar mold while contacting with a part of the outer periphery of columnar mold, are the main constituting elements, and one or more between contact positions of the molten metal pouring part and the belt 10 with the columnar mold and contact length of the columnar mold 1 with the belt 10 are made variable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting machine for a substrate used as a battery plate of a storage battery, particularly a lead storage battery for an automobile (hereinafter referred to as an automobile battery).

[0002]

2. Description of the Related Art An electrode plate for an automobile battery is referred to as an "active material". A powder of lead oxide is kneaded with dilute sulfuric acid to form a paste, which is then applied and dried. It is composed of two substrates that function as current collectors. There are roughly two methods for manufacturing a substrate, one of which is a casting method (hereinafter, a substrate manufactured by the casting method is referred to as a casting substrate), and the other is an expanding method.

Most of the cast substrates are made in pairs by a batch type book mold type casting machine, but recently, as shown in, for example, US Pat. No. 4,534,404, a rotating columnar body. A continuous casting machine using a mold has been developed, and hundreds to thousands of substrates are cast continuously. Needless to say, this method has extremely high productivity, and one continuous casting machine can be used for book mold type casting machines 7-8.
It has a production capacity equivalent to that of a vehicle. FIG. 2 shows an outline of the structure of a continuous casting machine which has recently been put into practical use. This continuous casting machine distributes a cylindrical mold 1 having an engraved portion 3 corresponding to the cross-sectional shape of the substrate on the outer peripheral surface 2 and a molten lead alloy (hereinafter simply referred to as molten metal) to the engraved portion,
The hot water supply unit 4 for supplying hot water is a main component. The hot water supply part is attached to the outer periphery of the rotating cylindrical mold in a state of having a sufficient degree of adhesion so that the molten metal 8 does not enter the contact part. The molten metal supplied into the engraving part moves in the direction of the arrow while contacting the inner surface of the hot water supply part as the cylindrical mold rotates, and the contact part between the hot water supply part and the cylindrical mold (L 'shown in FIG. 2). Solidifies while passing through. The base body 9 thus formed is released by the scraper 7 and directly sent to the filling step or wound into a coil.

Although this continuous casting machine has high productivity as described above, it also has a major drawback. As described above, the molten metal supplied to the engraving portion completes solidification before it separates from the hot water supply portion. During this time, the molten metal during solidification moves while contacting the hot water supply portion, that is, an external force acts on the substrate during solidification. This means that the basic condition that "external force should not be applied to the casting during solidification in order to prevent casting cracking" is not satisfied. In fact, it is difficult to cast a Pb-Sb alloy substrate having a high crack susceptibility by this continuous casting machine, and there is almost no solidification temperature range and the crack susceptibility is low.
Applicable only to casting of Ca alloy substrates.

In order to solve such a big drawback of the conventional continuous casting machine, we have proposed the Japanese Patent Application No. 3-621 of the prior application.
No. 17 proposes a new continuous casting method for a substrate using a cylindrical mold, a hot water supply unit, a belt integrally rotating with the cylindrical mold, and a casting machine as a main component. We call this the belt drum system, and Fig. 3 shows the outline of the continuous casting machine by this system. This casting machine is similar to a conventional continuous casting machine, and has a cylindrical mold 1 having an engraved portion 3 corresponding to the cross-sectional shape of the substrate on the outer peripheral surface 2.
The main components are a (drum), a hot water supply unit 4 for distributing the molten metal to the engraved portion, and an endless belt 10 that comes into contact with a part of the outer periphery of the cylindrical mold and rotates integrally with it. is there. In this system, the molten metal 8 supplied from the melting pot to the hot water supply part is distributed to the engraving part here, like the method of FIG. However, in FIG. 2, the molten metal in the engraved portion is solidified between the hot water supply portion and the mold, whereas in the belt drum system, the molten metal is not solidified when passing through the contact portion between the hot water supply portion and the cylindrical mold. And solidify between the belt located behind it and the cylindrical mold. That is, in this method, since the belt and the cylindrical mold rotate integrally, the force from the belt does not act on the molten metal during solidification, and casting of the Pb-Sb alloy, which was difficult by the method of FIG. 2, is performed. It will be possible.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As mentioned above,
The drum-type continuous casting machine completely solves the big problem of the conventional method. Initially, in the belt drum type continuous casting machine that we developed, the hot water supply part was fixed directly above the cylindrical mold, and the positions of the tension roll and the two guide rolls were also fixed. However, in order to improve productivity and to cope with casting of many alloy substrates having different compositions, improvement is required so that a wider range of casting conditions can be selected. This is because, for example, there were the following problems. That is, the method of FIG. 2 is the same,
In the belt drum type continuous casting method, since the mold rotates, a complicated force acts on the molten metal in the engraved portion. In particular, when the casting speed, that is, the rotation speed of the cylindrical mold, is large, a large centrifugal force acts on the molten metal, so that the molten metal overflows from the engraved part between the hot water supply part and the belt, and the molten metal in the adjacent engraved part The phenomenon of bridging occurs. As a result, the molten metal fills the space between the crosspieces of the substrate, and the desired substrate cannot be formed.
Although such a state can be sometimes solved by adjusting the temperature of the molten metal (casting temperature) in the hot water supply unit or the temperature of the cylindrical mold, there are times when it is impossible at all.

Further, in the case of Pb-Sb alloy, the solidification temperature range increases with the decrease of the amount of Sb, and in the case of Sb1%, it reaches about 70 ° C. That is, an alloy with a small amount of Sb requires a long time to solidify, and if it is not allowed to reduce the casting speed in order to secure the production amount, the solidification time must be shortened by some means. Of course, it is possible to set the casting conditions by adjusting the casting temperature and the mold temperature, but sometimes it is not possible to deal with this alone.

[0008]

In order to solve the above-mentioned problems and enable a wide range of casting conditions to be selected, the molten metal pouring portion can be moved along the outer peripheral surface of the cylindrical mold.

The contact start position and contact length between the belt and the cylindrical mold are variable.

The following two functions are added. FIG. 1 shows the structure of a belt drum type continuous casting machine to which the above-mentioned functions are added. In order to achieve the purpose of
Support frame 1 that rotates around the same axis with the rotating shaft 11 of FIG.
The structure is supported by 2. The hot water supply unit 4 is formed so as to come into close contact with the outer peripheral surface 2 of the cylindrical mold via the spring 13, and the close contact force is adjusted by changing the compression amount of the spring 13 with the handle 14. On the other hand, movement of the hot water supply unit along the surface of the cylindrical mold is caused by the handle 15
This is done by moving the connecting rod 16 connected to the support frame 12. By doing so, the position of the hot water supply unit can be varied within a certain range above the cylindrical mold.

In order to achieve the purpose of (1), the positions of the tension roll 17 and the guide roll 18 located on the side (upper side) where the belt and the cylindrical mold start to contact each other are adjusted. That is, the guide roll 18
Is supported by a support frame 19 which rotates around the axis of rotation of the cylindrical mold 1 as a fulcrum in the same manner as the hot water supply unit, and its position is adjusted by a handle 20.
This is done by moving the connecting rod 21 connected to. The position of the guide roll 22 on the side (lower side) where the belt separates from the cylindrical mold 1 is fixed. Further, the tension roll 17 is structured so as to be movable on the support frame 24 integrally with the spring 23 that applies tension to the belt. Then, for example, when increasing the contact length between the belt and the cylindrical mold, the handle 25 moves the tension roll 17 along the support frame 24 to the cylindrical mold side and at the same time moves the guide roll 18 to the hot water supply unit side. Let

[0012]

The function of making the hot water supply unit movable along the outer peripheral surface of the cylindrical mold, that is, making the hot water supply position adjustable facilitates selection of casting conditions. Since the cylindrical mold is rotating as described above, centrifugal force acts on the molten metal. This force works to lift the molten metal from the engraved part. There is also the effect of gravity, which of course always acts downwards on the melt. Considering the effects of both centrifugal force and gravity, the molten metal is most stable at the position where the component perpendicular to the engraved bottom of gravity becomes large, that is, immediately above or near the cylindrical mold. (However, since the temperature of the molten metal decreases from the time it is supplied to the engraved part, the fluidity also decreases accordingly. This works to stabilize the molten metal in the engraved part, which is not the case in all cases. However, by adopting a structure in which the hot water supply portion can be moved as in the present invention, a portion where nothing is suppressed from above in the engraved portion, that is, a portion from the hot water supply portion to the belt is directly above the cylindrical mold or It can be set near it. In other words, the variable hot water supply position facilitates selection of casting conditions.

Further, by varying the positions of the tension roll and the guide roll as described above, the contact length between the belt and the cylindrical mold can be changed. In particular, with respect to the point that the contact length can be increased, the effect is great because it is easy to set the casting conditions for cracking as in the Pb-Sb alloy. Furthermore, in the structure described above,
The distance from the hot water supply unit to the belt can also be adjusted. The molten metal supplied into the engraving part in the hot water supply part solidifies while coming into contact with the belt, but when the distance from the hot water supply part to the belt is changed, the degree of decrease in the molten metal temperature changes at this part. That is, the cooling rate of the molten metal during solidification changes, which changes the age hardening characteristics of the substrate. If the distance is shortened, the molten metal is cooled more rapidly, so that it becomes easier to age-harden, while if it is longer, the age-hardening becomes slower.

[0014]

EXAMPLES Next, examples of the present invention will be described. As described above, a belt-drum type continuous casting machine in which the position of the hot water supply part and the contact length between the belt and the cylindrical mold can be changed was prototyped, and the effects of the present invention were confirmed. The outline of the prototype casting machine is as follows. The cylindrical mold is made of cast iron with a diameter of 413 mm and a width of 220 mm, and is equipped with a cooling pipe inside 50 ± 2 ° C.
It has a structure that circulates temperature-controlled water. The hot water supply portion is made of aluminum bronze, and the dimensions of the contact portion with the cylindrical mold are 96 mm in the circumferential direction and 200 mm in the width direction. The height of the hot water supply part is 85 mm. At the bottom of the hot water supply unit, 21 slits having a cylindrical mold with an axial dimension of 2 mm and a circumferential dimension of 28 mm are provided, and one slit having an axial dimension of 4 mm and a circumferential dimension of 15 mm is provided. From here, the molten metal was supplied to the engraving part. The cylindrical mold was provided with engravings for nine substrates having a width of 144 mm, a height of 106 mm, and a thickness of 1.2 mm. In addition, the hot water supply part is ± 2 around the axis of the cylindrical mold with the position directly above the cylindrical mold as the reference.
It is possible to move only 0 degrees. The method of supporting the hot water supply unit and the moving mechanism are as described above.

The belt is made of stainless steel and has a thickness of 0.2.
The width is 5 mm and the width is 160 mm. All guide rolls are made of stainless steel and have a diameter of 120 mm and a width of 180
mm. The lower guide roll is fixed, and the position where the belt separates from the cylindrical mold is 20 degrees clockwise with respect to the axis directly below the cylindrical mold as the center of the axis of the cylindrical mold. Adjustable by moving the tension roll, the contact length between the belt and the cylindrical mold is about 43.
It is 0 to 550 mm. The distance from the hot water supply unit to the belt that can be adjusted as a result of moving the positions of the hot water supply unit 4 and the upper guide roll 18 is about 20 to 140 mm.

Table 1, Pb-1.5Sb-0.1As-
When a 0.02Se alloy substrate was cast at a pouring temperature of 480 ° C., a mold temperature of 160 ° C. and a casting speed (peripheral speed of the mold) of 30 m / min while changing the position of the hot water supply part, the substrate caused by the bridge of the molten metal This is the result of examining the shape defect.

[0017]

[Table 1]

The position of the hot water supply portion in the table is represented by an angle measured around the axis of the cylindrical mold with the position directly above the cylindrical mold as a reference, plus means clockwise and minus means counterclockwise. The distance from the hot water supply unit to the belt is fixed at 25 mm. As is clear from the table, defects occur while the hot water supply unit is on the belt side, and it is necessary to move by +5 degrees or more from directly above the cylindrical mold to perform casting in order to obtain a good substrate. . In this case, it was possible to obtain good results even if moved to +20 degrees, but when the casting speed was low, there was a phenomenon in which the molten metal dropped partially from the hot water supply section at +20 degrees, and good results were obtained. I can no longer.

Table 2 shows the results of examining the occurrence of casting cracks when the contact length between the belt and the cylindrical mold was changed.
The two cases of casting speed of 25 m / min and 35 m / min were investigated. The position of the hot water supply part is +10 degrees, and the pouring temperature and the mold temperature are the same as in Table 1.

[0020]

[Table 2]

In the Pb-Sb type alloy, since the Sb content is low and the solidification temperature range is wide, casting cracks occur when the contact length is short and cooling tends to be insufficient. When the contact length increased, it decreased, and when the casting speed was 25 m / min, the occurrence of cracks was not observed when the contact length was 490 mm or more.
Adjustable limit of 550 mm at 35 m / min
No cracks were observed for the first time. On the other hand, Pb-Ca
In the case of the system alloys, since there is almost no solidification temperature range, no cracking was observed within the experimental range. It can be seen from the results in Table 2 that varying the contact length between the belt and the mold is very effective. In particular, as in the case of changing the casting speed of Pb-Sb alloy, the casting speed can be increased by 1.4 times by increasing the contact length by 60 mm, and the productivity is dramatically improved. The points are notable.

[0022]

As described in detail in the embodiments, according to the present invention, the casting machine can select a wide range of casting conditions. For example, a design change may result in a material that is prone to casting defects or the size of the substrate may change. It is possible to easily deal with such cases. Further, it is possible to effectively cope with the improvement of productivity, and the effect of the present invention is extremely large.

[Brief description of drawings]

FIG. 1 is a view showing the structure of a continuous casting machine for substrates according to the present invention.

FIG. 2 is a diagram showing an outline of a structure of a conventional continuous casting machine.

FIG. 3 is a diagram showing an outline of a structure of a conventional continuous casting machine.

[Explanation of symbols]

1: cylindrical mold, 2: outer peripheral surface of cylindrical mold, 3: engraved part, 4: hot water supply part, 5: heater, 6: cooling pipe, 7: scraper, 8: molten metal, 9: substrate, 10: belt, 11:
Rotation axis, 12, 19, 24: support frame, 13, 23: spring, 14, 15, 20, 25: handle, 16, 2
1: connecting rod, 17: tension roll, 18, 22: guide roll

Continued front page    (72) Inventor Doen Toritoku             832 Horiguchi, Katsuta City, Ibaraki Prefecture 2nd Co., Ltd.             Hitachi Research Laboratory, Hitachi Ltd.

Claims (4)

[Claims] 1. A cylindrical mold having an engraved portion corresponding to the cross section of a substrate on the outer peripheral surface, a hot water supply portion for distributing molten alloy to the engraved portion, and a part of the outer periphery of the cylindrical mold, the contact portion In the continuous casting machine for battery electrode plate bases, the main component is a belt that rotates integrally with the cylindrical mold, and the hot water supply portion is located above the cylindrical mold. . 2. A cylindrical mold having an engraved portion corresponding to the cross section of the substrate on the outer peripheral surface, a hot water supply portion for distributing the molten alloy to the engraved portion, and a part of the outer periphery of the cylindrical mold to contact the cylindrical die. A continuous casting machine for electrode plate base pairs for a battery, wherein one or more of the contact positions of the pouring part and the belt with respect to the mold and the contact length between the belt and the cylindrical mold are variable. 3. A belt rotates via one tension roll and two guide rolls, the position of one guide roll is fixed, and the positions of the tension roll and another one guide roll are variable. The continuous casting machine for a battery electrode plate base pair according to claim 2, wherein 4. The battery electrode plate according to claim 2, wherein the guide roll and the hot water supply unit whose positions are variable are supported by a support frame which rotates about a rotation axis of a cylindrical mold as a fulcrum. Continuous casting machine for substrates.