SE453967B - PROCEDURE FOR CONTINUOUS SHAPING OF A TRADE - Google Patents

Description

453 967 device 32 during machining.

In conventional plants, a chamber 18b, which is formed by the housing 18, and which forms a channel for the scraped wire 11, is connected to a vacuum source via a line 42 for evacuating the chamber during machining. Such a device is disclosed in Japanese Patent No. 39-18204.

The scuffed line 11 is thus brought into the evacuated atmosphere before it is introduced into the dough 24. Therefore, the connection between the core wire and the stoned metal shell built up around the core wire is not affected, and moreover the metal built up on the core wire does not swell and have no pores.

It has now been found that when the channel for the scraped core wire, for example the chamber 18b in the housing 18 is kept in a sufficiently dehumidified, dry atmosphere, the metal built up on the core wire does not swell out and have no pores.

In view of this, it has also been found that the swelling of the built-up metal and the formation of pores in the metal is not caused by oxidation on the surface of the core wire but by absorption of moisture in the air towards the surface of the core wire. It has therefore been considered that the housing chamber 18b can suitably be kept in dry atmospheric air instead of in an evacuated atmosphere. As a result, the housing 18 does not have to be hermetically sealed. This entails large savings in terms of installation and maintenance costs. In addition, it is not necessary to have a vacuum pump to keep the chamber 18b under vacuum, and furthermore, the problem when the chamber 18b is kept under vacuum is avoided by forcing the molten metal M in the dough 24 to leak into the chamber 18b along the inlet 24a to 1111. dege1n 24. When the chamber 18b is kept in dry atmospheric air, this problem is thus eliminated. By this current method, the dip molding can be carried out in a stable manner.

However, when the chamber 18b is kept in dry atmospheric air, the dough 24, which contains the molten metal, is exposed and which is heated to a high temperature for oxidation at the bottom of the dough, which is in contact with the dry air in the chamber 18b. Therefore, the service interval of the dough 24 is reduced, and continuous handling for a long time can not be performed; which from an economic point of view is inappropriate.

The invention therefore has for its object to provide a method for continuously forming a tree for long periods in a stable and economical manner without requiring the channel of the scraped or peeled wire to be hermetically sealed.

The present invention thus relates to a method for continuously forming a tree, which method comprises the following steps: a) cleaning the surface of the continuously fed core trees; b) introducing the surface-cleaned core wire into a duct containing an atmosphere of an inert gas and a slightly reducing gas at a pressure 453 967 above atmospheric pressure; inserting said core wire from the channel into a molten metal bath and passing the wire through this bath to build up the molten metal on the wire to form a casting wire consisting of the core wires and a coating formed thereon from solidified metal; dl and hot rolling of the casting wire to a wire with a reduced cross-section.

The invention will now be described in more detail with reference to the accompanying drawings. In the drawings, Figure 1 schematically shows a wire forming device designed according to prior art. Figure 2 is a schematic view of a part of a wire forming device designed in accordance with the invention. Figure 3 schematically shows a modified wire forming device, and Figure 4 is a view similar to Figure 3 but showing another modified wire forming device.

Figure 2 shows a part of a device 10 for forming a wire by a method according to the present invention. The device is similar to that in Figure 1. A core wire 11 is passed through an abrasive disk 20 mounted on the inlet side of a housing 18, the abrasive disk cleaning the surface of the core wire 11. The housing 18 encloses a chamber 18b which forms the bushing channel for the scraped or peeled core wire. A gas supply pipe 46 is connected at one end to the housing lß and at its other end to a gas source (not shown), and a valve 48 is mounted in the supply pipe 46 for regulating the gas flow.

During operation, the chamber or channel 18b in the housing 18 is evacuated by means of an evacuation line 42. Thereafter, the valve 48 is opened and gas with a pressure above atmospheric pressure is continuously fed into the chamber 18b from the gas source via the supply line 46, so that the chamber 18b is filled with gas. The gas is either of the weakly reducing (non-oxidizing) type or of the inert type. Thereafter, the core wire cleaned or surface peeled through the abrasive disk 20 is introduced into the chamber 18b, so that the abraded core wire is exposed to either a pressurized reducing atmosphere or an inert atmosphere under pressure. Thereafter, the scraped core wire 11 is passed upwardly by a drive roller 16 and inserted into a crucible 24 through its inlet 24a, so that a molten metal M, e.g. copper, builds up on the core wire and forms a casting rod 13. The built-up metal solidifies and forms a coating around the core wire. During operation, the chamber 18b of the housing 18 is maintained at a pressure above atmospheric pressure, so that the ambient air is effectively prevented from entering the chamber 18b even if the housing 18 is not of a hermetically sealed construction. Therefore, the built-up metal or coating on the casting rod 13 is not subjected to swelling and no pores are formed. In addition, oxidation at the bottom of the crucible 24 is prevented.

EXAMPLE 1 A wire was prepared using the device shown in Figure 2.

The chamber 18b in the housing 18 was evacuated through the evacuation line 42, and a mixed gas of 95% N 2 and 5% CO was fed into the chamber 18b from a gas source through the supply line 46 at a pressure of 100 mm H 2 O at a rate of 5 m 3 / h, so that the chamber 18b came to contain a slightly reducing atmosphere at a pressure slightly above atmospheric pressure; Thereafter, a core wire of copper was peeled by means of the abrasive disk 20, and the wire was inserted into the chamber 18b. The scraped core wire, which had a diameter of 12.7 mm, was further fed upwardly through the chamber 18b and inserted into the crucible 24 through its inlet 24a, so that the molten copper in the crucible 24 was continuously piled on the fed core wire to form a casting rod. The casting rod was continuously hot rolled into a tree with a diameter of 8 mm.

A comparison wire was also prepared according to the process described above except that the chamber 18b was kept under vacuum. The properties of the threads prepared according to the invention and comparison trees were determined. The results are shown in the following table l.

Table l sample 0 present wire comparative wire characteristic tensile strength 23,5 '23,3 elongation' 40 4l twist test * g - no defect 'no defect cross section * ï no bouudary found no boundary found and no defect and no defect * Varje wire was twisted ten times in one direction and then ten times in the opposite direction.

** The cross section of each wire was observed using a microscope.

As can be seen from Table 1, the wire of the present invention exhibited almost the same quality as the conventional wire.

Figure 3 shows a modified tree forming device 10a, which differs from the device 10 in Figure 2 in that the surface cleaner 50 replaces the abrasive disk 20, and in using only a pair of cooperating oval calibration blades 34 and only one pair of cooperating round calibration sleeves 36. The oval calibration hubs 34 weld the cast rod to an oval cross-section, while the round calibration sleeves 36 weld the rod to a circular cross-section. The surface cleaner 50 is located immediately upstream of the housing 18 and consists of a wire brush and a blasting device. The device may also include a degreasing means for chemically degreasing the core wires 11 before it is cleaned by the surface cleaning means 50. The surface cleaning means 50 may also consist of a chemical cleaning means containing a degreasing means, a pickling means and a dryer. An abrasive disk of the type used in the previous embodiment serves to cut a thin layer of meta11 from the outer surface of the core wire 11, and the disk is therefore designated for wear in its cutting de1. In the case where the core wire 11 is made of steel, the abrasive disc is soon damaged and must be replaced by a new one. Frequent replacement of the abrasive disc therefore prevents continuous machining for a long time. The wire brush and the mounting member do not adversely affect a continuous machining for a long time even in the case that the core wires 11 are of hard metal 11 such as steel. Since in this present embodiment the abrasive disk is not used, there is no need for a drive roller such as the drive roller 16 in Figure 1 to create an appropriate tension in the core wire 11 to enable the abrasive disk to abrade the core wire.

The casting rod 13, which consists of the core element 11 and the surface coating of the metal built up around the core wire, is hot-rolled by a hot-rolling device 32 into a wire of a predetermined diameter. The core element and the built-up metal of the casting rod 13, which are fed from the dough 24, are not metallurgically bonded to each other at their interfaces. The metallurgical connection between the two parts is effected by the hot welding. In the case that the core element 11 and the molten metal built up around the element have different compositions, it is relatively difficult to hot-weld the casting rod to a uniform cross-section over the entire length of the trees. If, for example, the casting rod 13 consists of a steel core element and the metal structure of a copper layer, the strength properties of these two parts are different, and it is then difficult to heat-weld the solid casting rod to a uniform cross-section. Therefore, each time the casting rod 13 is hot rolled by the oval calibration pads or the round calibration pads to reduce the cross-sectional area, the irregularities in thickness on the copper coating increase, thereby increasing the irregularities on the joint in the joint.

In the present embodiment, for this reason, the casting rod emanating from the dough 24 is hot-rolled only twice, i.e. first by the pair of oval calibration rollers 34 and then by the pair of round calibration rollers 36. The degree of reduction of the cross-sectional area of the casting rod in the combined rolling with the oval calibration rollers 34 and the round calibration rollers 36 is not more than 40%. In this process, the irregularities of the rolled wire can be kept to a minimum. If the degree of reduction is more than 40%, the irregularities in the thickness of the copper layer or copper alloy on the core element increase above an acceptable level.

EXAMPLE 2 A wire was prepared using the apparatus of Figure 3. The chamber 18b of the housing 18 was evacuated through the evacuation line 42, and a gas of weakly reducing nature was fed from the gas source into the chamber 18b over the supply line 46, so that the chamber 18b became a slightly reducing atmosphere at a pressure slightly above atmospheric pressure. Thereafter, a mild steel core wire having a diameter of 9.5 mm was continuously subjected to a surface cleaning by means of the surface cleaning member 50, which removed oxide layers and rust from the core element surface. The surface cleaner consisted of a tree brush. The surface-cleaned core wire was introduced into the chamber 18 and fed further through the crucible 24 through its inlet 24a at a speed of 70 m / min, so that the molten copper in the crucible 24 formed a coating on the core wire, so as to continuously obtain a casting rod having a diameter of l3 mm. The casting rod consisting of the steel core element and the copper coating was then passed through a cooling tower 30 and hot rolled in a non-oxidizing atmosphere by means of a hot rolling device 32 to a wire with a diameter of 11 mn. The degree of reduction in this hot rolling was 13%. The thickness of the copper coating in the resulting trees was measured to determine the weight ratio. The maximum thickness of the copper coating was 0.05 mm, while the minimum thickness was 1.45 mm, and the average thickness was 1.48 mm.

The weight ratio of the copper coating was about 50%, but it can be varied by controlling the feed rate of the core element as it passes through the crucible 24.

Figure 4 shows another modified wire forming device 10b, which differs from the device in Figure 3 in that it contains a heating device 54 in the chamber 18b in the housing 18. A surface-cleaned core wire 11 is passed through the heating device 54, through which the wire is heated to a predetermined temperature before it is fed into the crucible 24. It has been found that the amount of molten metal built up on the core wire depends on the temperature of the core member. the amount of molten built-up 453 967 metal is increased in proportion to the amount of heat absorbed by the core element 11 in the dough 24. Therefore, when the temperature of the core element 11, which is heated by the heating device 54, is relatively low, the coating on the casting rod 13 becomes relatively thick. On the other hand, if the core element 11 is heated by means of the heating device 54 to a higher temperature, the coating on the casting rod 13 becomes thinner. The thickness of the coating can be controlled by means of the heating device 54. By this method, the volume ratio of coating in relation to the core element, i.e. the ratio in cross-sectional area, varies within the limits between 10 and 70%. Furthermore, if the core element has a relatively flat cross-section such as a strip, then the temperature profile of the core element can be made uniform, so that a coating of uniform thickness can be provided on the core element.

EXAMPLE 3 A wire was made using the apparatus shown in Figure 4. The chamber 18b to the housing 18 was evacuated through the evacuation line 42, and a 2% H2 mixed gas and the remainder NZ was fed from the gas chamber into the chamber 18b over the feed pipe 45. The chamber 18b is raised with a slightly reducing atmosphere at a pressure slightly above atmospheric pressure. A gas mixture consisting of 2% H2 and the remainder NZ was also introduced into the housing of the hot washing device 32. Thereafter, a 9.5 mm diameter mild steel core wire was subjected to a surface cleaning using a wire brush to remove the oxide layer and rust from the outer surface of the wire. The surface-cleaned core wire was inserted into chamber 18b and passed through the heater 54 to raise the temperature of the trees. The heated core wire was fed into the die 24 through the inlet 24a, so that molten pure copper in the die 24 was built up on the fed core wire, so that a casting rod was continuously formed. Thereafter, the casting rod was hot-rolled to a wire of predetermined diameter in a slightly reducing atmosphere (2% H 2 and the residue N 21). the relationship between the temperature of the core wire and the thickness of the copper layer built up was determined.The results are shown in the following table 2. 453 967 8 Table 2 2.02 61 2oo ° c 10.0 i .os see 4oo ° c 9 .o n. 44 21 As can be seen from Table 2, the weight ratio of copper on the wire varies within wide limits depending on the temperature at which the wire is heated in the heating device 54.

Claims (5)

453 967 P a t e n t k r a v A method for continuous dip forming of a wire, characterized by the following steps: a) a continuously fed core wire of steel is subjected to a non-cutting surface cleaning (20) by blasting or steel brushing; b) the surface-cleaned core wire (11) is introduced into a channel (18b) in an atmosphere of an inert gas or a slightly reducing gas at a pressure above atmospheric pressure; c) the core wire (11) is led from said channel (18b) to a bath (24) of molten metal and passed through the bath, so that the molten metal (M) builds up on the core wire and forms a casting rod (13) consisting of said core wire and a coating formed around the core wire, which is derived from the solidified metal; d) the casting rod is fed immediately after leaving the bath (24) into a cooling tower (30a); and e) the casting rod (13) is hot-rolled directly from the cooling tower (30a) into a reduced cross-section wire with a reduction degree of not more than 40%. Method according to claim 1, characterized in that the hot rolling is carried out by guiding the casting rod (13) through a pair of cooperating oval calibration rollers (34) and a pair of cooperating oval calibration rollers (36). Method according to claim 1, characterized in that the core wire (11) is heated to a predetermined temperature in the initial channel (18b) for controlling the thickness of the applied surface layer in the casting rod (13L). Process according to Claim 1, characterized in that the hot rolling takes place in an atmosphere of an inert gas or a slightly reducing gas. Method according to claim 1, characterized in that the core wire (11) and the molten metal (M) have different chemical composition.