JPS6145698B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a brass material used as a terminal base material or the like.

BACKGROUND ART Conventionally, a conductive layer of a good conductor such as copper is formed on the surface of a brass material by plating, thereby reducing the contact resistance of the brass material. In this way, by forming a conductive layer on the surface of the brass material, the raw material cost is lower than when using a highly conductive material such as copper as is, and the contact resistance is about the same. benefits will arise. However, the conventional method as described above has the problem that the plating apparatus is large and the productivity is low. Furthermore, since the conductive layer formed by plating is easily peeled off, it is extremely difficult to bend the brass material, which has become a hoop material, into parts after plating. It was hot too.

Therefore, by heating the brass material under reduced pressure to evaporate the zinc on the surface, it is possible to create a brass material 1 having a conductive layer 1a with a high copper content on the surface, as shown in FIG. thought out. If the brass material is manufactured in this way, there is no need to use other metal materials, and compared to the case of plating, the manufacturing equipment can be smaller and the productivity is higher. Moreover, the resulting conductive layer of the brass material has little risk of peeling off.

The inventor focused on this method of manufacturing brass material and conducted repeated research in an attempt to improve the performance of the obtained brass material against stress corrosion cracking and prevent deterioration of strength.
As a result, it was discovered that the growth of brass crystals in the core of the brass material could be suppressed by heating rapidly to evaporate the zinc and then rapidly cooling, thereby completing the present invention.

In other words, this invention rapidly heats the brass material as a raw material in producing a brass material with a conductive layer containing a large amount of copper on the surface by heating the brass material under reduced pressure to evaporate the zinc on the surface. conduct,
The gist is a method for producing brass material that is characterized by rapid cooling after evaporating zinc. This invention will be explained in detail below.

FIG. 2 shows an example of manufacturing equipment used to carry out the method for manufacturing brass materials according to the present invention. As shown in the figure, this manufacturing device is equipped with an unwinding drum 2 and a winding drum 3. A brass material 4, which is a raw material used as a hoop material, is wound and mounted on the unwinding drum 2. A brass material 5 that has been subjected to a dezincing treatment is wound onto the wire 3. Between the unwinding drum 2 and the winding drum 3, a cleaning device 6,
A heating chamber 7, a cooling chamber 8, and a rolling mill 9 are provided in this order, and the brass material 4 sent from the unwinding drum 2 passes through these in order. The cleaning device 6 is for removing dirt such as oil adhering to the brass material 4. The heating chamber 7 includes a high frequency coil 10 and a temperature sensor (infrared radiation thermometer) 1.
1 is placed. A high frequency power source 12 is connected to the high frequency coil 10 for causing a high frequency current to flow therethrough. A temperature controller 13 is connected to the temperature sensor 11 and the high frequency power supply 12. A zinc collector 14 for recovering zinc is arranged around the inside of the heating chamber 7. Heating chamber 7
An inlet 15 and an outlet 16 of cooling water for the zinc collector are respectively provided on the lower surface as shown by the arrows. A pressure sensor 17 is disposed in the cooling chamber 8, to which inert gas is sent from an inert gas cylinder 18 through a flow rate adjustment valve 19. Entrance of heating chamber 7, heating chamber 7
Vacuum chambers (seals) 20a, 20b, 20c are provided between the outlet of the cooling chamber 8 and the inlet of the cooling chamber 8, and at the outlet of the cooling chamber 8.
are provided for each. Vacuum chambers 20a, 20
b and 20c are provided with a valve 21, a vacuum pump (rotary) 22, and a vacuum pump (mechanical) 23, respectively.

Using this operation, brass material is made as follows. After the raw material brass material 4 mounted on the unwinding drum 2 is sent to a cleaning device 6 for cleaning, it is sent to a heating chamber 7 where it is rapidly heated by induction heating under reduced pressure. That is, the vacuum chamber 20a or 20b
The pressure inside the heating chamber 7 is reduced by the vacuum pumps 22 and 23 arranged in the high-frequency coil 10.
A high-frequency current is passed through the high-frequency coil 10 to rapidly heat the brass material 4 passing through the high-frequency coil 10. For example, heating chamber 7
When the internal pressure is about 10 ^-2 to ^{10 -4} Torr (higher vacuum than about 10 ^-2 Torr), the brass material is rapidly (in a few seconds) heated to about 500 to 900°C. Zinc evaporates at 1 atm with a boiling point of 930°C, but from 10 ^-2 to
10 ^-4 Torr, which is close to a complete vacuum, is 500~
Evaporates at around 900℃. On the other hand, copper has a boiling point of 2582° C. at 1 atmosphere, which is much higher than zinc, and hardly evaporates at the above pressure and temperature. Utilizing such a difference in boiling point (difference in vapor pressure) between zinc and copper, zinc 24 on the surface of the brass material 4 is selectively removed, as shown in FIG. 4. Then, a conductive layer 4a containing a large amount of copper is formed on the surface of the brass material 4.

After performing the dezincing treatment, the brass material 4 is sent to a cooling chamber 8 and rapidly cooled. That is, after reducing the pressure in the cooling chamber 8 with the vacuum pump 23 of the vacuum chamber 20b or 20c, the pressure is increased to about 500 Torr with an inert gas, and the brass material is heated using the conduction and convection effects of the inert gas. Rapidly cool 4. In this way, when brass material is cooled in an inert gas atmosphere,
There is no risk of copper oxidation during cooling.

Brass material 4 at a pressure of 500 to 900 at a pressure of 10 ^-2 to 10 ^-4 Torr.
FIG. 3 shows the temperature and pressure distributions in the heating chamber 7 and the cooling chamber 8 when the chamber is heated to .degree. C. and cooled to room temperature under an atmospheric pressure of 500 Torr. In the figure, the solid line represents atmospheric pressure, and the dashed line represents temperature.

In this device, the heating temperature in the heating chamber 7 is controlled as follows. That is, the surface temperature of the brass material 4 is measured in a non-contact manner using the infrared radiation thermometer 11, and a signal of the measured temperature is transmitted to the temperature controller 13. Temperature controller 1
3 calculates the difference from the set temperature and sends a signal according to the result to the high frequency power source 12 (feedback). The high frequency power supply 12 receives this signal and adjusts the current flowing through the high frequency coil to adjust the surface temperature of the brass material 4 to the set temperature. The pressure in the cooling chamber 8 is controlled as follows. First, the pressure in the cooling chamber 8 is measured by the pressure sensor 17, and a signal corresponding to the measurement result is sent to the flow rate adjustment valve 19 (feedback). The flow rate adjustment valve 19 receives this signal and controls the amount of inert gas sent from the inert gas cylinder to the cooling chamber 8.
Keep the internal pressure constant.

The cooled brass material 4 is sent to a rolling mill 9, where it is rolled to a predetermined thickness. Immediately after cooling, the brass material 4 has improved electrical properties due to high temperature heating;
As shown in FIG. 5, the zinc evaporates and pores 25 are formed, resulting in a decrease in mechanical properties, that is, strength, and a rough surface. However, rolling improves the strength and makes the surface flat.
The brass material 5 obtained by rolling is wound around a winding drum 3.

The brass material obtained in this way is heated rapidly,
Rapid cooling suppresses the growth of brass crystals in the core. Therefore, performance against stress corrosion cracking is improved, and there is less risk of deterioration in strength.

The rapid heating method is not limited to the method described above, and other methods such as the following can be considered.

As an indirect heating method, for example, the following method can be considered. As shown in Figure 6,
A coil 27 is wound around the outer periphery of the heating chamber 26, and a high frequency current is passed through the coil from a high frequency power source 28 to heat the entire heating chamber. Then, the brass material 4 passing through the heating chamber 26 is indirectly heated by radiation heating.
Instead of the coil 27, a resistance heating element may be arranged around the outer periphery of the heating chamber 26, and a current may be passed through the resistance heating element. In the figure, 29 is a cooling chamber.

As a direct heating method, the following methods can be considered, for example. As shown in Figure 7,
Electron beam or laser beam irradiation devices 30 are arranged above and below inside the heating chamber 31, and, for example, the electron beam or laser beam is scanned back and forth in a direction at 90 degrees Celsius with respect to the direction of movement of the brass material 4. The surface of the material 4 is uniformly irradiated and heated.
In the figure, 29 is a cooling chamber. Further, as shown in FIG. 8, two current collectors 33 are arranged in the heating chamber 32 along the direction in which the brass material 4 moves. Then, the tip of the current collector 33 is brought into contact with a brass material, and a large current at a low voltage is caused to flow between the two current collectors 33 by the power source 34. Then, Joule heat is generated due to the resistance of the brass material 4 itself, and the brass material 4 is heated. The calorific value of the brass material 4 is given by the current I, both collectors 3
Letting R be the resistance of the brass material between 3 and 33, it is expressed as I ² R. In this way, when a high-frequency current is caused to flow from the power source, the current density near the surface of the brass material 4 becomes higher than that inside the brass material 4 due to the skin effect, so that the near surface is heated preferentially. Therefore, the thermal influence on the four-core portion of the brass material is reduced, and the effect of preventing the growth of brass crystals becomes even higher. In the figure, 35 is a roll, which is provided for the purpose of supporting the brass material 4 to prevent poor contact between the brass material 4 and the current collector 33. other than this,
Another possible method is to place a high-frequency electrode in the heating chamber and directly rapidly heat the brass material by dielectric heating.

All of the conventional rapid heating methods heat both sides of the brass material at the same time, but it is also possible to heat one side at a time. As such a divided heating method, for example, the following method can be considered. As shown in FIG.
While arranging the first roller 37a in 6,
A second roller 37b is arranged diagonally below the front of the first roller 37a, so that the direction of movement of the brass material 4 is opposite between the first roller 37a and the second roller 37b. Then, the lower surface of the brass material 4 located between the first roller 37a and the second roller 37b is heated by the first heating device 38a, and the lower surface of the brass material 4 that has passed the second roller 37b (the (the surface opposite to the surface) is heated by the second heating device 38b. As the heating devices 38a and 38b, a laser beam or electron beam irradiation device or the like is used. When the brass material is heated one side at a time in this way, a layer with a high copper content (dezincing layer) is formed.
It becomes easier to control the thickness. Another advantage is that the manufacturing equipment can be made more compact.

The rapid cooling method is not limited to the methods described above, and for example, the following methods can be considered.

As shown in FIGS. 10 and 11, a cooling roll 40 is placed in the heating chamber 39,
A turn roll 41 is placed diagonally below the front of the cooling roll 40.
Place. The turn roll 41 is provided for the purpose of increasing the contact area between the brass material 4 and the cooling roll 40. The cooling roll 40 is configured to allow cooling water to pass therein. In the figure, 42 is a heating device, 43 is a vacuum seal, and 44 is a rotary joint. After being heated by the heating means 42 to perform dezincing treatment, the brass material 4 is wound around a cooling roll and rapidly cooled. Using a cooling roll in this manner has the advantage that heating and cooling can be performed in the same room.

Note that the rolling process after cooling the brass material is not necessarily required unless it is necessary to adjust the thickness to a predetermined thickness by rolling. However, by rolling the brass material, the mechanical properties of the brass material can be improved and the surface can be made smooth. The brass material used as a raw material is not limited to a hoop material, and may be, for example, a wire rod. Further, the material is not limited to a long material, but may be a short material. However, if brass materials are produced continuously using long materials, productivity will be extremely high, as will rapid heating and cooling. Heating is performed in a high vacuum as much as possible, and cooling is performed in a high vacuum or an inert gas atmosphere as much as possible to prevent the formation of an oxide film on the conductive layer and prevent deterioration of the electrical properties of the brass material. So far, an example has been described in which the conductive layer is provided on both sides of the brass material, but the conductive layer may be provided only on one side.

The method for producing a brass material according to the present invention is configured as described above, in which the brass material as a raw material is rapidly heated, zinc is evaporated, and then rapidly cooled, so that the growth of brass crystals is suppressed. be done.
Therefore, the performance of the obtained brass material against stress corrosion cracking is improved, and the possibility of deterioration of strength is reduced.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing a part of a brass material with a conductive layer with a high copper content cut away on its surface;
The figure is a schematic explanatory diagram of an example of a manufacturing apparatus used to carry out the manufacturing method according to the present invention, and FIG. A graph showing an example, Fig. 4 is an explanatory diagram when dezincing brass materials, Fig. 5 is an enlarged view of circle A in Fig. 4, Fig. 6 is an explanatory diagram of a rapid heating method by radiation, Figure 7 is an explanatory diagram of the rapid heating method using electron beam or laser light, Figure 8 is an explanatory diagram of the rapid heating method using Joule heat, Figure 9 is an explanatory diagram of the divided heating method, and Figure 10 is rapid cooling using cooling rolls. Explanatory diagram of the method, 1st
FIG. 1 is a sectional view taken along line B-B in FIG. 10. 1, 5... Brass material, 1a, 4a... Conductive layer, 4
... Brass material as raw material, 7, 26, 31, 32,
36, 39... Heating chamber, 8, 29... Cooling chamber, 1
0, 27... High frequency coil, 30... Irradiation device,
33...Collector, 40...Cooling roll.

Claims (1)

[Claims] 1. To produce a brass material with a conductive layer containing a large amount of copper on the surface by heating the brass material under reduced pressure to evaporate the zinc on the surface, the brass material as a raw material can be heated rapidly. A manufacturing method for brass material characterized by rapid cooling after evaporating the zinc. 2. Claim 1, wherein the heating of the brass material is one selected from induction heating, radiation heating, electron beam heating, laser beam heating, and Joule thermal heating.
Manufacturing method of brass material described in section. 3. The method for producing a brass material according to claim 1 or 2, wherein the cooling of the brass material is at least one of cooling by contact with an inert gas and cooling by a cooling roll.