JPS5919187B2 - Bright annealing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for bright annealing brass and other copper alloys in a substantially oxygen-free hydrogen atmosphere.

Conventionally, when bright annealing brass wire, etc., this is done in a hydrogen reducing atmosphere in a d-bell furnace or pot furnace, but in this case, a large amount of hydrogen gas must be flowed to replace the air in the furnace. Not only is this process uneconomical because it consumes a large amount of hydrogen gas, but there is also the risk of explosion due to the mixture of hydrogen and oxygen in the air, which poses a difficult problem in terms of work safety management.

In addition, unless the dew point of the gas in the furnace is lowered considerably, moisture in the gas will thermally decompose during annealing and oxidize the surface of the metal material, so that a sufficient bright annealing effect will not be achieved.

Therefore, a method has been proposed in which ammonia cranking is performed in the furnace to generate a mixed gas atmosphere of nitrogen and oxygen as a relatively inexpensive and large quantity supplying reducing atmosphere to the bright annealing furnace. However, this method requires complex and expensive equipment to remove moisture from the ambient gas and sufficiently lower its dew point.

The present invention has been made to solve these problems, and will be described in detail below.

The inside of the sealed annealing furnace containing the metal material to be brightly annealed is made to have a vacuum of about -2 mmH, and then nitrogen gas from liquid nitrogen and hydrogen gas from a hydrogen cylinder are appropriately mixed to separate hydrogen gas. A small amount of mixed gas at a pressure of around 4% is injected, and the mixed gas is used to repeatedly clean the metal material and the inside of the furnace for deoxidation and dehumidification under reduced pressure, and then the annealing temperature is lowered. During heating and temperature rise, the above-mentioned mixed gas of chiron and hydrogen was injected into the annealing furnace to release the expanding gas pressure inside the furnace so that the internal pressure was slightly higher than the external pressure. The nitrogen and hydrogen gas inside is allowed to escape from the opening, and the mixed gas is replenished from the other opening to constantly maintain the pressure inside the furnace slightly higher than the outside pressure.

Therefore, the annealing temperature, for example in the case of brass, is about 500 to 55
Once the temperature reaches 0°C, the temperature is maintained for a while, for example, 30 to 60 minutes, and then during the cooling stage, a mixed gas is supplied in an amount that is equal to or more than the shrinking gas volume in the furnace, so that the pressure inside the furnace is constantly raised slightly higher than the outside pressure. Let it be.

In this manner, the desired bright annealing is achieved by cooling the metal material in an atmosphere containing a mixture of chiron and hydrogen and then taking it out of the furnace.

In carrying out the present invention, the degree of pressure reduction in the furnace when cleaning the inside with a mixed gas of nitrogen and hydrogen is 0.01kplcr&
It is preferable that the partial pressure of hydrogen gas in the cleaning step and the cooling step following the annealing step is about 4%. The pressure difference between the inside and outside of the furnace in the cooling process may be about 0.01 kg/d.

The advantages of the method of the present invention are summarized and separately described as follows.

(1) Since liquid nitrogen is used as the nitrogen source, the oxygen content is very low and the moisture content is high, so if the degree of oxidation of the metal material to be annealed is not very advanced, expensive hydrogen may be used. It requires only a very small amount and is very economically advantageous.

(2) Since the annealing process and the processes before and after it are carried out in a mixed gas of hydrogen and nitrogen with a partial pressure of hydrogen gas of about 4%, it is possible to operate outside the explosion limit, which is extremely advantageous in terms of work management. It also means that it can be implemented at low cost.

(3) The inside of the annealing furnace is evacuated to a level of -2 mm, and then the above mixed gas is repeatedly used under a reduced pressure of about 0.01 kg/cyrt to clean the inside of the furnace. Trace amounts of oxygen gas and moisture remaining in the furnace can be removed from the system, so in the next annealing process, the effect of bright annealing is sufficient even in a mixed gas atmosphere or air where the partial pressure of hydrogen gas is low. is achieved.

((1) In the temperature raising process, annealing process, and cooling process, the pressure of the mixed gas in the furnace is constantly raised to about 0.01 kg/d higher than the external pressure, so there is no risk of outside air entering the furnace and it is safe. Moreover, the desired bright annealing effect is guaranteed.

(5) Bright annealing process (
The amount of mixed gas used for heating and cooling (including heating and cooling before and after) is extremely small, and the amount of expensive hydrogen gas is only around 4% of the mixed gas, which is even more advantageous. It is safe and has great industrial value.

Examples of the present invention are shown below.

In Fig. 1 of F-1, 9 is red copper (C) drawn with a wire drawing machine.
This is a wire rod of about 500 to 90 wires (a coil may be used).

When drawing the wire 9, it is necessary to use a lubricant that completely evaporates at approximately 300°C and leaves no residue that may cause bleeding, and to install a wiping device in front of the winding device. It is important to wipe off as much excess oil as possible.

It is generally better not to degrease with a tri-crane.If you choose an appropriate oil and wipe it off thoroughly, even if there is a small amount of oil left on the surface of the wire, or if it is tightly wound around a coil etc., it will not work under vacuum. When heated, it evaporates and does not affect the finish much.

Such wire rods 9 are stacked by hooking them onto a pole 10 installed on a lower electric furnace 8 installed on a pedestal 2.
0 is for stacking the bundles to prevent them from collapsing, and depending on the product, an appropriately provided shelf or the like may be used.

Next, the Matsupuru (protective container) 3 is lifted up by a crane and placed over the electric furnace 1, and then the clamp 6 is tightened to seal the space between the Matsufuru and the furnace stand.

The inner diameter of Matsuful is approximately 1l100ix, and the height is 1400mm.
The internal volume is approximately 1,3001.

Water is flowed through the purification pipe 7, then the bell-shaped electric furnace 1 is turned on, and at the same time as heating is started, the vacuum pump 13 shown in FIG. 2 is turned on.

Before that, I close valve V-3 and open V-1, but valves V-2, V-4, and V-5 are closed.

After about 10 minutes, the temperature inside Matsufuru 3 reaches 50°C or more, and the degree of vacuum becomes 2-3siH5.

Then, open the valves V-4 and V-5, adjust the pressure of the microinjection bypass circuit 14, and inject a very small amount, for example, about 1.
Flow the mixed gas at a rate of 31/min to completely replace the remaining air in the Matsufuru (about 10 minutes).

At this time, care must be taken to ensure that the degree of vacuum does not exceed 8iiwI, that is, 0.01y72.

The mixed gas is N2 from the liquid nitrogen tank 15 and N2 from the hydrogen cylinder 16 in a volume ratio of about 96:4.
The mixture is mixed in an automatic mixing device 17 and stored in a receiver tank 18 .

With this operation, 0.13 of 17100 of the 13 m3 of gas required to exchange the air in the Matsufuru 10 times under one atmospheric pressure.
The content of 02 can be lowered by the same ratio with m', and since the atmospheric pressure is less than 01 kg/cr7, it is possible to further reduce the content of 0□■ to 1/100 or less.

In other words, □ gas 00 can increase the effect 100 times, and if N2+H
If the 02 content in the two gases is ippm or less, the 02 content in the almost Matsufuru can also be made to be IPPm or less.

Next, close the valve V-1 to turn off the vacuum pump, close the valve V-4, and open the valve V-2 to rapidly fill the Matsufuru with gas.

The vacuum gauge 24 returns to 760 mrnflj9, and as the temperature inside Matsuful rises, it increases to 7 to 10 rILnHfl/
The internal pressure rises at a rate of 1 minute.

Close the valve V-2, and open the valve V-3 to release the expanding gas so that the internal pressure (positive pressure) rising by the vacuum gauge 24 is stopped within about 8 mmwI (0.01 kg/d).

(0 to 181/min), and the temperature inside the Matsufuru reaches 550° C., which is a sufficient annealing temperature for red copper wire, in about 2 hours.

Valve V-4 is reopened and held there for approximately 1 hour, using trace bypass 14 to replenish trace amounts of gas.

After holding for about an hour, turn off the electric furnace and lift it with a crane to remove it.To quickly cool down the Matsufuru, cover it with a cooling hood and spray with cold water or blow cold air.

At this time, always adjust the pressure of the trace gas injection bypass 14 to ensure that the inside of the matsuful does not become depressurized.

After the temperature inside Matsuful has dropped to about 50℃, the slight bypass 14 is opened, the valve V-3 is opened, and air is injected.
Remove the items, excluding the matsufuru.

The red copper wire is completely annealed and has a tensile strength of approximately 28~30kg/
ma) and its gloss and color are not impaired at all.

The true line (in the case of 65%Cu735%Zn) is 550
At ℃, the luster is lost, probably due to rapid evaporation of Zn.
It is better to do this at a temperature below 500°C.

If done at around 470°C, the beautiful luster will not be lost.

As described above, according to the method of the present invention, (1) Despite the extremely small amount of gas used (see above 5.
In 00ky annealing, the amount of 96%N2 + 4%N2 gas used is only 4m' at maximum at one time) ■ Extremely safe gas whose main component is N2 gas from liquid nitrogen and contains approximately 4% N2 gas. (The explosion limit of N2 is 4.1%), and at the same time, it is possible to displace and remove the air in the Matsufuru, that is, 0□.

■ At the same time, excluding volatile oils, there is no negative effect on color luster.

■ Cu alloys can be annealed with extremely high gloss and excellent color.

■Equipment costs and gas costs are both low, making it extremely economical considering the pickling process, the associated labor, and pollution prevention costs.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional diagram of a bright annealing furnace used in carrying out the method of the present invention, and FIG. 2 is a circuit diagram of an embodiment of the method of the present invention. 1... Bell-shaped electric furnace, 2... Frame, 3
...Matsuful, 4...Rubber backing, 5...Heat-resistant seal, 6...Clamp, 7
......Cooling pipe, 8...Lower electric furnace, 9.
...Wire, 10...Pole, 11...
...Gas inlet, 12...Exhaust port, 13...
...Vacuum pump, 14...Micro injection bypass, 15...Liquid nitrogen tank, 16...
・Hydrogen cylinder - 17... Automatic gas quantitative mixing device, 18... Receiver tank, 19...
Flowmeter (capacity 0 to 301/min), 19'...Flowmeter, 20...Primary pressure regulator, 21...
...Secondary pressure regulator, 22...Pressure regulator and valve, 23...Check valve, 24...
Vacuum gauge, 25... Manometer, 2
6... Release bar/lz7", V-1 to V-5
······valve.

Claims (1)

[Claims] 1 When bright annealing copper alloys such as brass in a hydrogen atmosphere that does not substantially contain oxygen, the inside of the closed annealing furnace containing the above metal materials is first evacuated, and then nitrogen gas from liquid nitrogen and a hydrogen pump are used. A small amount of mixed gas with a hydrogen gas partial pressure of about 4% is supplied into the furnace, and these mixed gases are used to clean the metal materials and the inside of the furnace for deoxidation and dehumidification. The annealing process is repeated under a reduced pressure of about 0.01 kg/ffl, and then the above-mentioned mixed gas is supplied into the annealing furnace so that the internal pressure is higher than the external pressure, and while replenishing this mixed gas, the external pressure is lowered. Also 0.01kg/
cr? A bright annealing method characterized by maintaining a high internal pressure of about L, increasing the temperature in the furnace to the annealing temperature of the metal material, and then taking out the metal material from the furnace after cooling under the same pressure condition.