JP2635833B2 - Plasma powder overlay - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma powder build-up torch for performing build-up welding using powder.

[0002]

2. Description of the Related Art In order to improve the metal surface (abrasion resistance, heat resistance, corrosion resistance, etc.), overlay welding has been conventionally performed. That is, in the build-up welding process, powder metal is supplied into a plasma arc column, melted and injected onto a welding surface together with the plasma arc, and the metal surface is built up with the weld metal. The torch used for this is disclosed, for example, in
No. 72 discloses this.

The tip of this type of torch is, for example, shown in FIG.
Alternatively, the structure is as shown in FIG. In each figure, 51 is a tungsten electrode, 52 is a plasma gas, 5
3 is powder, 54 is powder carrier gas, 55 is cooling water, 5
6 is a shield gas, 57 is a plasma arc column, 58 is a deposited metal, 59 is a base material, and 60 is a nozzle member. In the torch shown in FIG. 5, the nozzle member 60 is provided with a plasma injection hole and a plurality of powder supply holes 60a formed around the plasma injection hole. Through the passage 31, the powder is supplied from the powder supply hole 60 a into the plasma arc column 57. Between the lower opening of the powder carrier gas supply passage 31 and the upper opening of the powder supply hole 60a, there is a ring-shaped space surrounding the arc hole. In the torch shown in FIG. 6, two nozzles 6 are arranged concentrically.
Plasma nozzles are narrowed and ejected by an inner nozzle 61, and a powder 53 together with a carrier gas 54 is supplied from a gap between the two nozzles to a plasma arc column 57.
Supply within.

[0004]

In this type of plasma powder cladding torch, the powder carrier gas channel 60a of the nozzles 60 to 62 may be clogged with powder. If one of the gas passages 60a becomes clogged, the distribution of the deposited metal 58 on the base material 59 is disturbed, and a desired shape of the overlay cannot be obtained.

An object of the present invention is to prevent clogging of a powder flow path of a nozzle member.

In the conventional torch, the nozzle member (6
0 to 62), the vertical position with respect to the torch main body is defined, but the circumferential position or posture around the central axis of the arc hole is free. Therefore, the nozzle member (60 to 6) with respect to the powder carrier gas supply passage of the torch main body.
2) The position (in the circumferential direction) of the powder carrier gas flow path is randomly determined at the time of assembling the torch or disassembling and reassembling, and the metal powder for overlaying is located above the nozzle members (60 to 62). The nozzle member (60 to
When entering the upper opening of the powder carrier gas flow path in 62) through the ring-shaped space between the lower opening and the upper opening, the outlet of the powder carrier gas supply path and each powder carrier gas flow The distance to the road entrance is often different for each channel,
When the distance difference is large, the metal powder flows relatively vigorously in the powder carrier gas flow path of a short distance, but the metal powder easily stays in the powder carrier gas flow path of a long distance. It was found that the flow of the powder was obstructed to further increase the retention, and such a vicious cycle eventually led to clogging.

[0007]

In view of such a phenomenon, in the present invention, an arc hole (17) through which a plasma arc generated between the main electrode (1) and the base material (41) passes is provided. Is formed in the center,
A first set of powder flow passages (12) through which the powder passes is distributed at equal intervals around the central axis of the arc hole (17) and extends in a direction approaching and toward the central axis. Nozzle member (10); and a plurality of nozzle members (10) distributed at regular intervals around the center axis of arc hole (17) for supplying powder from above to first set of powder flow paths (12). A second set of powder flow paths (31); and a second set of powder flow paths (31) and arc holes.
A projection member (33) for positioning the nozzle member (10) such that the first set of powder flow paths (12) is distributed symmetrically with respect to a straight line connecting the central axis of (17), and the projection member (33). Receiving recess (34)
One of them being the torch body and the other being the nozzle member.
Provided on the outer surface of (10). The symbols in parentheses indicate the corresponding elements in the embodiments described later.

[0008]

According to this, when the nozzle member (10) is mounted on the torch, the second set of powder flow paths (31) and the arc are formed by the projection members (33) and the concave portions (34). The nozzle member (10) is positioned so that the first set of powder flow paths (12) is distributed symmetrically with respect to a straight line connecting the center axis of the hole (17). This position allows the first
The channels which are symmetrical to each other in the set of powder channels (31) are the second channels.
The powder flow from the second powder flow path (31) is evenly received at equal distances from each of the sets of powder flow paths (12), and the powder from the second powder flow path (31) In this case, the flow of the powder is substantially equal in each flow path, and the powder concentrates in one flow path, and the powder does not substantially stay in the other flow path. Since the positioning of the nozzle member (10) is always performed reliably, clogging of the powder in the first set of powder flow paths (12) in the nozzle member (10) does not easily occur.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0010]

1 shows the structure of the tip of a plasma torch for powder overlay welding according to the present invention. FIG. 1 shows different cross sections of the right half and the left half of the torch, and shows a cross section taken along line A1-A1 of FIG. 3 corresponding to the torch plan view. Referring to FIG. 1, a rod-shaped electrode 1 made of tungsten is arranged at the center of the torch, and the electrode 1 is fixed to the torch by a chuck 2. The tip 1a of the electrode 1 has a sharp shape, and the tip 1a is arranged at the center of an arc hole 17 formed at the center of the nozzle member 10. Reference numeral 20 denotes a centering stone for positioning the electrode 1 at the center of the member 10. The plasma gas is supplied from the outside through a space between the electrode 1 and the chuck 2, passes through a hole 8 a formed in the support member 8, passes through a space between the electrode 1 and the centering stone 20, and is centered. Through a hole 21 formed in the stone 20,
It is guided to an arc hole 17 of the nozzle member 10. This plasma gas is ionized by an arc discharge between the electrode 1 and the base material 41 to form a high-temperature plasma arc stream 43.

The powder and the powder carrier gas for transporting the powder are supplied from the outside of the torch, pass through the powder pipe 7, and are formed in two nozzle holes 30 (powder carrier gas supply passage). The gas is injected toward the plasma arc flow 43 through the four holes (powder carrier gas flow passages) 12 formed in the nozzle member 10 and injected into the plasma arc flow 43. The powder is melted by the heat of the plasma arc stream 43 and becomes a molten metal 42 to cover the welding surface on the base material 41.

The shield gas 44 is injected through the space 6 between the nozzle cap 5 and the casing 3 so as to cover the periphery of the plasma arc flow 43, and shields the welding surface from the outside air. In order to prevent overheating of the nozzle member 10,
Cooling water is supplied from the outside of the torch to the nozzle member 1 through the hole 32.
0 is supplied to the groove 11 formed.

FIG. 2 shows a vertical section of the plasma torch shown in FIG. 1 at a further different angle from that of FIG. This longitudinal section is shown in FIG. 3 corresponding to the torch plan view.
3 is a cross section taken along line A2-A2 of FIG. In FIG.
A pin 33 is fixed to the hole of the pin 3 by press-fitting.
The tip of 3 protrudes into the nozzle member receiving hole of the nozzle table 30. A groove 34 for receiving the tip of the pin 33 is formed in the upper end of the nozzle member 10. The groove 34 is open on the upper end surface and the side peripheral surface of the nozzle member 10. As shown in FIG. 2, when the nozzle member 10 is assembled to the torch body (30), the tip of the pin 33 is located in the groove 34.
The nozzle member 10 cannot rotate in the circumferential direction about the center axis of the arc hole 17 (electrode 1).

FIG. 3A is an enlarged plan view of the nozzle member 10, and FIG. 3B is a longitudinal sectional view taken along line A3B-A3B of FIG. Referring also to FIGS. 1 and 2, in this embodiment, four powder carrier gas flow paths 12 are formed in the nozzle member 10 at intervals of 90 degrees around the arc hole 17, The groove 34 is formed in the middle of two adjacent gas flow paths 12, that is, at a position at an angle of 45 degrees with the two gas flow paths 12. Two powder carrier gas supply paths 31 are formed symmetrically with respect to the electrode 1 on the nozzle base 30 of the torch main body, and a pin 33 is connected to a straight line Ls connecting the two gas supply paths 31 and an electrode. 1 are installed at a position and a posture orthogonal to the central axis.

When the nozzle member 10 is connected to the nozzle base 30, the nozzle 10 is inserted into the nozzle receiving hole at the center of the nozzle base 30.
Insert the upper end (sleeve) of the nozzle cap 5 and screw the nozzle cap 5 to the nozzle base 30 to some extent. And nozzle 1
0 until its upper end surface hits the tip of the pin 30,
Next, the nozzle member 10 is rotated around the electrode 1 to rotate the groove 3.
4 is fitted to the tip of the pin 30. Thereby, the nozzle member 1
Since 0 can be further pushed, the nozzle member 10 is further pushed. Thereby, the tip of the pin 33 enters the groove 34.
Then, the nozzle cap 5 screwed to the nozzle base 30 is tightened, and the nozzle member 10 is tightened to the uppermost part. Then, the cover-3 is mounted on the nozzle base 30 by screw connection. As a result, the nozzle member 10 shown in FIG.
In other words, as shown in FIG.

In this state, the pins 33 of the nozzle base 30 are
And powder carrier gas supply path 31 and nozzle member 10
The positional relationship between the groove 34 and the powder carrier gas flow path 12 is as shown in FIG. 3A: plan view and FIG. 4 (perspective view). That is, four powder carrier gas flow paths (symmetrically with respect to a straight line Ls connecting the powder carrier gas supply path (the second set of powder flow paths) 31 and the central axis of the arc hole 17 (electrode 1)). A first set of powder flow paths) 12 are distributed. Note that there is a ring-shaped space between the lower opening of the powder carrier gas supply channel 31 and the upper opening of the powder carrier gas channel 12. In this state, the powder carrier gas flow path 12 and the powder carrier gas supply path 31 located on the groove 34 side with respect to the straight line Ls
Is equal to the distance between the powder carrier gas flow path 12 and the powder carrier gas supply path 31 on the opposite side of the groove 34. As a result, the powder carrier gas flows evenly in the gas flow path 12 on the groove 34 side and the gas flow path 12 on the opposite side of the groove 34, and powder does not easily stay in the powder carrier flow path 12. That is, clogging of the flow channel 12 hardly occurs. In this embodiment, in particular, the powder carrier gas supply path 31 is one pair, and the powder carrier gas flow paths 12 are two pairs, so that all of the gas flow paths 12 are equidistant from the supply path 31. Therefore, the effect of preventing clogging of the flow channel 12 is high.

Although two pairs of powder carrier channels 12 are formed in the nozzle member 10 in the above embodiment, for example, three or four pairs of powder carrier channels 12 may be formed. Good. That is, six flow paths 12 at intervals of 60 degrees or eight flow paths 12 at intervals of 45 degrees are formed symmetrically with respect to the straight line Ls on the circumference. In this case, of the three or four flow paths 12 on the half circumference, the flow path at the center thereof has a longer distance from one supply path 31, but also has a longer distance from the other supply path 31. Since the powder flow is received, the flow rate difference between the individual flow channels 12 is not so large, and the effect of preventing the flow channel 12 from being clogged is sufficient.

[0018]

In any case, according to the present invention, symmetrically with respect to a straight line connecting the second set of powder flow paths (31) of the torch body and the central axis of the arc hole (17), In order to ensure that the first set of powder channels (12) of the nozzle member (10) is always distributed, the nozzle member
(10) is positioned. By this positioning, the mutually symmetrical flow paths in the first set of powder flow paths (31) are equidistant from each of the second set of powder flow paths (12) and are evenly powdered. When receiving the body flow and the powder from the second powder flow path (31) proceeds to the first powder flow path (12), the flow of the powder becomes substantially equal in each flow path, The powder concentrates in one flow path, and the powder does not substantially stay in the other flow path. Since the positioning of the nozzle member (10) is always performed reliably, clogging of the powder in the first set of powder flow paths (12) in the nozzle member (10) does not easily occur.

[Brief description of the drawings]

1 is a longitudinal sectional view of a main part of one embodiment of the present invention, and is a longitudinal sectional view taken along line A1-A1 of FIG.

FIG. 2 is a longitudinal sectional view of a main part of the embodiment, and FIG.
2 is a vertical cross-sectional view taken along line A2-A2 of FIG. 1, showing a cross section different from the cross section shown in FIG.

3 is an enlarged view of the nozzle member 10 shown in FIGS. 1 and 2, FIG. 3 (a) is a plan view, and FIG. 3 (b) is a sectional view taken along line A3B-A3B of FIG. 3 (a).

FIG. 4 shows a nozzle member 10 shown in FIGS. 1, 2 and 3;
FIG. 4 is an enlarged perspective view of FIG.

FIG. 5 is a longitudinal sectional view of a tip portion of a conventional plasma powder cladding torch.

FIG. 6 is a longitudinal sectional view of a tip portion of another conventional plasma powder cladding torch.

[Explanation of symbols]

1: Electrode (main electrode) 2: Chuck 5: Nozzle cap 7: Powder tube 8: Support member 10: Nozzle member (nozzle member) 11: Cooling water channel 12: Powder carrier gas channel (first set of powder) 13: concave portion 14: inclined surface 17: arc hole 20: centering stone 21: hole 30: nozzle base 31: powder carrier gas supply path (second set of powder flow paths) 33: Pin (projection member) 34: Groove (recess) 41: Base material 42: Molten metal 43: Plasma arc flow 44: Shield gas

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-218772 (JP, A) JP-A-2-192699 (JP, A) JP-A-4-94167 (JP, U) 11717 (JP, Y1)

Claims (1)

(57) [Claims] An arc hole through which a plasma arc generated between a main electrode and a base material passes is formed in a central portion, and is distributed at equal intervals around a center axis of the arc hole. A plurality of nozzle members having a first set of powder passages through which the powder passes, and a plurality of nozzle members extending in the direction approaching and downward; and for supplying powder to the first set of powder passages from above, A plasma powder cladding torch having a plurality of second sets of powder flow paths distributed at equal intervals around the center axis of the arc hole; A projection member for positioning the nozzle member so that the first set of powder flow paths are distributed symmetrically with respect to a straight line connecting the central axis of the through hole, and a concave portion for receiving the projection member. A plasma powder build-up torch characterized in that the other is provided on the outer surface of the nozzle member.