JP2003092110A - Mold for continuous casting of lead-acid battery grid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for continuous casting of a lead-acid battery grid capable of remarkably prolonging the mold life even in sever heat cycles only by slightly increasing a mold production cost. SOLUTION: A casting mold of a lead-acid battery grid is engraved with an NC engraving machine in a mold material having a surface hardness of HRc25 to HRc35, made of an iron alloy containing C, Si, Cr, Mo, and V, and the lead-acid battery grid is continuously casted using a ring-shaped mold material 1, a casting mold 2 formed on the surface, and a rotating shaft 3 of the mold material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a lead storage battery grid.

[0002]

2. Description of the Related Art A molten lead alloy is continuously supplied from a nozzle that constantly slides on a cylindrical surface to the engraving of a cylindrical surface lattice shape of a die formed on the outer peripheral surface of a rotating cylinder. A continuous casting apparatus for a lead storage battery grid body that solidifies and continuously takes out a lead alloy casting body to manufacture a lead storage battery grid body is disclosed in, for example, US Pat. Some are listed in 4,349,067.

[0003]

In the above continuous casting apparatus, the surface of the rotating cylindrical mold rises to a high temperature when the molten lead alloy is supplied from the nozzle, and at the same time, the cooling water flowing inside the mold. Will be cooled from the inside,
Exposed to severe heat cycles.

Although there is no description about the material of the rotating cylindrical mold in the above-mentioned patent, when carbon steel which is usually used for a mold is used, the surface is heated by the above heat cycle even with a slight use. Cracks due to thermal fatigue called check occur. If such a heat check occurs in a large amount, it naturally cannot serve as a mold.

When an iron-based mold material is used, as a means for improving the heat check resistance, it is known to increase the surface hardness of the mold.

However, if the hardness is increased, it becomes difficult to process the die. This is a serious problem in a mold having a fine and complicated shape such as a lead storage battery grid.

Therefore, the conventional Rockwell hardness HR
Although carbon steel or the like that has been tempered to c30 or less was often used, the heat check resistance was insufficient.

Further, in the case of alloy tool steel or the like, which is usually used after being refined to HRc 40 or more, the heat check resistance is remarkably improved, but it becomes practically impossible to process it as a lead storage battery grid die. There is a problem that ends up.

It is an object of the present invention to provide a die for continuous casting of a lead storage battery grid, which can greatly extend the die life even if the die manufacturing cost is slightly increased.

[0010]

A mold for continuous casting of a lead storage battery grid according to the present invention has a mold surface hardness of HRc25 to HRc35, and is made of an iron alloy containing C, Si, Cr, Mo and V. It will be.

Specifically, the following is done.

The components of the iron alloy are C, Si, Cr, Mo,
V must be included. The content of each component is C: 0.32% by mass to 0.42% by mass, Si: 0.80% by mass.
~ 1.20% by mass, Cr: 4.50% by mass to 5.50% by mass, Mo:
1.00 mass% to 1.5O mass%, V: 0.80 mass% to 1.20 mass%
By setting the range to be more effective.

Such iron alloys include, but are not limited to, so-called alloy tool steels.

This mold material must be formed into a shape suitable for processing. A ring (pipe) shape in consideration of the machining allowance is the best as the shape of the shape, but a columnar shape, a prismatic shape or the like may be used. However, care must be taken because the uniformity of the temper hardness is impaired as the number of processed and removed parts after the heat treatment increases. The molding method is preferably forging, but may be extrusion or drawing.

Next, the molded material is processed by a conventional method.
Quenched and tempered, HRc25 to HRc35
To temper. The temper hardness is H when considering the hardness variation.
About Rc30 is preferable because of ease of engraving, but any value may be adopted as long as it is within the above range for each part of the mold. However, if these values are deviated, the heat check resistance will be significantly reduced when the hardness is low, and the engraving of the grid will be difficult when the hardness is high, and in some cases it will be virtually impossible. Therefore, reliable management is necessary.

Subsequently, when the mold material is not in the ring shape,
It is processed into a ring shape so as to be incorporated into a mold roll.

Then, the mold ring is incorporated into the mold roll surface. The mold roll has water cooling grooves formed therein so that the mold surface can be cooled.

The mold ring incorporated in the mold roll is subjected to machining to remove the distortion so as to have a required roundness, and then a lattice is engraved to complete the mold.

[0019]

EXAMPLES Examples of the present invention and comparative examples will be described below.

(Example 1) C: 0.20% by mass, Si: 1.5
% By mass, Cr: 4.0% by mass, Mo: 0.8% by mass, V: 0.
A 1% by mass (variable range unknown, balance iron) iron alloy was formed into a ring shape by hot forging. The molded mold material was tempered and tempered to obtain HRc30. This mold material was assembled on the surface of the mold roll, and the surface of the mold material was cut and polished to a predetermined size with a lathe. The surface hardness of the die after cutting was HRc30.2 ± 2.8 on average.

(Example 2) C: 0.37 ± 0.02 mass%, S
i: 1.0 ± 0.1 mass%, Cr: 5.0 ± 0.3 mass%, M
An iron alloy of o: 1.3 ± 0.1 mass% and V: 1.0 ± 0.1 mass% (the balance of iron) was formed into a ring shape by hot forging. By quenching and tempering the molded mold material, HRc
Tempered to 30. This mold material was assembled on the surface of the mold roll, and the surface of the mold material was cut and polished to a predetermined size with a lathe. The surface hardness of the die after cutting was HRc30.7 ± 2.2.

Comparative Example 1 C: 0.45 ± 0.03% by mass, S
An iron alloy (S45C carbon steel) of i: 0.25 ± 0.1% by mass and Mn: 0.75 ± 0.15% by mass (remainder iron) was formed into a ring shape by hot forging. The molded mold material was tempered and tempered to obtain HRc30. This mold material was assembled on the surface of the mold roll, and the mold material meta was cut and polished to a predetermined size by a lathe. Mold surface hardness after cutting is HRc 30.5
It was ± 3.1.

(Comparative Example 2) C: 0.37 ± 0.02 mass%, S
i: 1.0 ± 0.1 mass%, Cr: 5.0 ± 0.3 mass%, M
An iron alloy of o: 1.3 ± 0.1 mass% and V: 1.0 ± 0.1 mass% (remainder iron) was formed into a ring shape by hot forging (same as in Example 2). The molded die material was tempered and tempered to obtain HRc40. This mold material was assembled on the surface of the mold roll, and the surface of the mold material was cut and polished by a lathe. The surface hardness of the die after cutting was HRc40.6 ± 2.8.

(Comparative Example 3) C: 0.37 ± 0.02 mass%, S
i: 1.0 ± 0.1 mass%, Cr: 5.0 ± 0.3 mass%, M
An iron alloy of o: 1.3 ± 0.1 mass% and V: 1.0 ± 0.1 mass% (remainder iron) was formed into a ring shape by hot forging (same as in Example 2). The molded die material was tempered at 1000 ° C. in air and then tempered at 600 ° C. to be tempered to HRc20.

This mold material was assembled on the surface of a mold roll, and the surface of the mold material was cut and polished by a lathe. The surface hardness of the mold after cutting was HRc20.3 ± 2.1.

The mold materials of Examples 1 and 2 and Comparative Examples 1, 2 and 3 were engraved with a NC battery engraving machine to form a lead storage battery grid mold, to obtain a mold as shown in FIG. In FIG. 1, 1 is a ring-shaped mold material, 2 is a mold of a lead storage battery grid formed on the surface of the mold material 1, and 3 is a rotating shaft of the mold material 1.

Using these molds, a lead storage battery grid was continuously cast. The temperature of the lead alloy is 500 ℃, the composition is Sb2.
7% by mass and the balance Pb alloy was used.

FIG. 2 shows the amount of heat check generated on the mold surface after continuous casting for a long time in Examples 1 and 2 and Comparative Examples 1 and 3. In Examples 1 and 2, the number is significantly smaller than that in Comparative Example 1, and it can be seen that Example 2 in which each alloy component is optimized is more excellent. Also,
In Comparative Example 3, although the same iron alloy as in Example 1 was used, the heat check was not reduced because the mold surface hardness was low.

FIG. 3 shows the processing time required for engraving the mold. In Comparative Example 2, the mold surface hardness was too high,
It became a level that was virtually impossible to sculpt. On the other hand, in Examples 1 and 2, the level was about 50% higher than that of Comparative Example 1, and the cost for manufacturing the mold was slightly increased with respect to the effect of extending the mold life.

[0030]

As described above, the mold for continuous casting of the lead storage battery grid according to the present invention has a mold surface hardness of HRc.
Since it is 25 to HRc35 and is made of an iron alloy containing C, Si, Cr, Mo and V, it is possible to significantly extend the life of the die even if the die manufacturing cost is slightly increased.

[Brief description of drawings]

FIG. 1 is a plan view showing an outer shape of a die for continuous casting of a lead storage battery grid according to an embodiment of the present invention.

FIG. 2 is a comparative diagram showing the amount of heat check generated on the mold surface during continuous casting for a long time in the example and the comparative example of the present invention.

FIG. 3 is a comparative diagram showing a processing time required for engraving a mold in an example and a comparative example of the present invention.

[Explanation of symbols]

1 Mold material 2 Lead acid battery grid mold 3 Mold material rotation axis

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C22C 38/00 302 C22C 38/00 302E 38/24 38/24 F term (reference) 4E093 NB09 5H017 AA01 BB02 BB15 BB19 CC05 HH00 HH01

Claims (2)

[Claims] 1. A mold for continuous casting of a lead storage battery grid body made of an iron alloy containing C, Si, Cr, Mo and V, having a mold surface hardness of HRc25 to HRc35. 2. The content of C is 0.32% by mass to 0.42% by mass, the content of Si is 0.80% by mass to 1.20% by mass,
The content of Cr is 4.50% by mass to 5.50% by mass, the content of Mo is 1.00% by mass to 1.50% by mass, and the content of V is 0.80% by mass to 1.20% by mass. Item 1. A mold for continuous casting of a lead storage battery grid according to Item 1.