Electric heating – Metal heating – For deposition welding
Patent
1996-04-02
1998-12-22
Shaw, Clifford C.
Electric heating
Metal heating
For deposition welding
37460, B23K 904
Patent
active
058522727
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to wear-resistant overlay forming methods for readily and efficiently giving wear resistance to parts which are locally subjected to wear such as a cutting edge of a wheeled loader, a ripper point of a bulldozer and a bucket tooth of a hydraulic shovel, and the invention also relates to wear-resistant composite members used for such parts.
BACKGROUND ART
For giving wear resistance to a part which is locally subjected to wear such as a cutting edge, ripper point and bucket tooth, a wear-resistant overlay having a composite structure constituted by a metal matrix (soft basis), hard particles and others is formed on a base material by an overlaying welding method, as disclosed, for instance, in Japanese Patent Publication Laid-Open No. 2-6097 (1990). Generally, hard particles are sprayed to and mixed with a molten weld pool formed on the base material during welding as described in the above publication in order to form such a wear-resistant overlay. This method however presents the problem that if the hard particles have higher density than the molten metal, the hard particles will precipitate in the molten weld pool, resulting in formation of a wear-resistant overlay within which the hard particles are not uniformly dispersed so that good wear resistance cannot be achieved.
If a conventional ripper point 100 for bulldozers is used for a long time, tip 103 composed of a top face 101 and a bottom face 102 which meet each other will be worn out as shown in FIG. 29(a). Therefore, the ripper point 100 having a ground-contacting section 104 which has been worn out and rounded as shown in FIG. 29(b) is usually used by turning it around as shown in FIG. 29(c). This turning operation decreases efficiency in digging operation.
The invention has been made to overcome the foregoing drawbacks, and one of the objects of the invention is therefore to provide wear-resistant overlay forming methods capable of forming a wear-resistant overlay in which hard particles are uniformly dispersed and capable of giving desired excellent wear resistance.
Another object of the invention is to provide wear-resistant composite members having high digging efficiency which ensure good penetration strength relative to the ground uniform when they are used for a long period, and ensure long service life.
DISCLOSURE OF THE INVENTION
The above objects can be accomplished by a wear-resistant overlay forming method according to the invention wherein hard particles are supplied to a molten weld pool that is formed on a base material by an arc generated from an arc electrode to form a wear-resistant overlay containing the hard particles on the base material, and wherein the hard particles are supplied to part of molten metal of the molten weld pool, the part being raised by the arc.
According to the invention, hard particles are supplied to part of the molten metal of the molten weld pool that is formed during arc welding, the part being raised by an arc. This allows the part of the molten metal to be solidified without precipitation of the hard particles in the molten weld pool so that the hard particles are uniformly dispersed in the resultant overlay to be obtained after solidification.
In the above wear-resistant overlay forming method of the invention, when an overlay is formed on the surface of the base material under the conditions that the surface of the base material is inclined in a welding direction at an angle .alpha. which ranges from not less than 0.degree. to less than 25.degree. with respect to a horizontal plane, the preferable arrangement is as follows: the tip of the arc electrode is inclined in relation to the surface of the base material so as to face in the direction opposite to the welding direction; and the hard particles are supplied to the part of the molten metal of the molten weld pool being raised by the arc, the part supplied with the hard particles being located behind an intersecting position in the welding direction, the intersecting position being where the ext
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Komatsu Ltd.
Shaw Clifford C.
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