JPS5831379B2 - contact tip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a contact tip for a welding torch used in gas-encapsulated arc welding, and more particularly to a contact tip used in consumable electrode arc welding.

Arc welding uses the high temperature of an arc to heat the welding part of the materials and melt the filler metal or welding rod and materials to join them. Depending on the electrode used, there are two types of arc welding: non-consumable electrode arc welding and consumable electrode arc welding. There is.

In consumable electrode arc welding, the arc has strong directionality, so it can be easily welded in any downward, vertical, or upward position.Compared to non-consumable electrode arc welding, it has the advantage of being able to achieve higher welding speeds. be.

The bath torch used in the above-mentioned consumable electrode arc welding has a structure as shown in the figure, for example.

That is, the contact tip 2 is provided inside the nozzle 1 with a gap serving as a gas passage.

The contact tip 2 is provided with a lead-out hole for an electrode wire 3 fed by a feeding roll (not shown).

The contact tip 2 guides the electrode wire 3 to a predetermined welding part (and energizes the electrode wire 3).

The electrode wire 3 is welded to the welding part while generating an arc between the electrode wire 3 and the welding part by energizing the contact tip 2.

Contact chips used in this manner are required to have good electrical conductivity and thermal conductivity, as well as good abrasion resistance and welding resistance at high temperatures.

In other words, in order to conduct electricity to the electrode wire, it is necessary to have good conductivity, and during arc welding work, the welding torch itself becomes hot due to the arc heat generated between the electrode wire and the welding part, and in this state, the electrode wire This is because it has to be sent.

More specifically, for example, carbon copper wire with a diameter of 1.2 mm is used as an electrode wire, and argon gas containing oxygen is used to generate a direct current with reverse polarity (
When welding with a current of about 20 OA (the electrode wire is the positive electrode), the temperature of the arc generated during welding is extremely high at about 6000°C, so the contact tip is also heated to about 700 to 800°C. The electrode wire must be fed at a high speed of 10 to 12 m/rnin.

On the other hand, the lead-out hole of the contact tip requires a certain degree of precision, and for example, when using the above-mentioned electrode wire with a diameter of 12 mm, it becomes unusable if the diameter of the lead-out hole opening becomes about 1.8 mm.

Therefore, it is required to have good wear resistance, especially under high temperature conditions.

Conventionally, contact tips made of a chromium-copper alloy have been used to meet the above characteristics requirements.

The contact tip made of chromium-steel alloy has particularly good conductivity and is excellent in this respect, but the lead-out hole wears quickly when the electrode wire runs, and the corners of the opening are particularly prone to wear. The problem was that it had a short lifespan.

In order to improve this point, for example, a contact tip made of a chromium-copper alloy to which other elements are added to increase its hardness or a contact tip made of a material harder than a chromium-copper alloy is used.

However, as mentioned above, the contact tip has a diameter of 1.2
Although it is necessary to precisely machine the studded lead-out hole, such contact tips with high hardness have extremely poor machinability and are expensive.

The present invention has been made to improve these difficulties, and focuses on a contact tip made of a chromium-zirconium copper alloy that has particularly good wear resistance and a long life, and provides a contact tip with improved machinability. be.

That is, in terms of weight, chromium 0.3 to 1.0%, zirconium 0.15 to 0.45φ, and rare earth elements 0.01 to 0.4
It is characterized by being made of a copper alloy containing copper.

Both chromium and zirconium have a future effect on improving strength, but if they are contained in large amounts, the electrical conductivity decreases, and the strength does not increase accordingly.

Further, since it is difficult to obtain the desired strength with a small amount, the above range is preferable.

In addition, the rare earth element content improves machinability, but 0
．． If it is less than 0.01 mm, there is no effect, and if it is more than 0.4 mm, the machinability is not improved to a certain extent and the conductivity is reduced, so the above range is preferable.

Furthermore, if the amount of silicon as an impurity exceeds 0.03, the conductivity decreases, which is not preferable.

Next, the present invention will be explained by citing typical examples thereof and comparing them with reference examples.

An alloy having the composition shown in Table 1 was melted and then hot worked to obtain a bar with a diameter of 101n7/L.

This was solution treated at 950°C for 1 hour and then aged at 450'C for 5 hours.

A contact tip with an inner diameter of 1 and QrnllL was made from this material.

The machinability and lifespan of the contact tips thus obtained are shown in Table 1 along with comparative examples.

In Table 1, machining time refers to the time required to form a hole with a diameter of 1 mm and length of 45 mm, and life refers to the time it takes for the inner diameter of the contact tip to wear down from 2.4 mm to 3 mm during use.

As is clear from this table, the contact tip according to the present invention has a much better life than the conventional contact tip made of chromium-copper alloy, has good machinability, and can be obtained in the desired shape at a low cost. .

In terms of characteristics, the conductivity of the contact tip according to the present invention is slightly inferior to that of chromium copper, but there is no problem in practical use, and therefore, the workability of welding work can be significantly improved by using the contact tip of the present invention. .

[Brief explanation of the drawing]

The figure is a sectional view showing a main part of the welding torch cut away. 1... Nozzle, 2... Contact tip, 3... Electrode wire.

Claims (1)

[Claims] 1% by weight chromium 0.3-1.0%, zirconium 0.15-0.45%, rare earth elements 0.01-0.4%
A contact chip characterized in that it is formed of a copper alloy containing 0.03% or less of silicon as an impurity, the remainder being substantially copper.