JPH04274882A - Plasma powder build-up torch - Google Patents

Abstract

PURPOSE:To prevent the clogging of plural pieces of powder flow passages 12 of a nozzle member 10. CONSTITUTION:A projecting member 33 is provided on a nozzle base 30 and a recessed part 34 accepting the projecting member 33 is provided on the nozzle member 10. The powder flow passages 12 of the nozzle member 10 are distributed symmetrically with a straight line Ls connecting the powder flow passage 31 of a nozzle stand 30 and the center line of an electrode 1. The powder flow rate from the powder flow passage 31 to the respective powder flow passages 12 is uniformized and the powder is prevented from stagnating in the any flow passages 12. The flow passages 12 are thus hardly clogged.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma powder overlay torch that performs overlay welding using powder.

0002

BACKGROUND OF THE INVENTION Overlay welding has been conventionally performed to improve metal surfaces (wear resistance, heat resistance, corrosion resistance, etc.). That is, in the overlay welding process, powder metal is supplied into a plasma arc column, and while it is melted, it is injected together with the plasma arc onto the welding surface, and the weld metal is used to overlay the metal surface. The torch used for this is, for example, JP-A-1-21
It is disclosed in Japanese Patent No. 8772.

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

0004

However, in this type of plasma powder overlay torch, the powder carrier gas passages 60a of the nozzles 60 to 62 may become clogged with powder. If one of the gas flow paths 60a is clogged, the distribution of the weld metal 58 on the base material 59 will be disturbed, making it impossible to obtain a desired shape of build-up.

[0005] An object of the present invention is to prevent clogging of the powder flow path of a nozzle member.

In the conventional torch, the nozzle member (6
0 to 62), their positions in the vertical direction with respect to the torch body are specified, but their positions or postures in the circumferential direction centering on the central axis of the arc hole are free. Therefore, the nozzle member (60 to 6
The position (circumferential direction) of the powder carrier gas flow path in 2) is randomly determined during torch assembly or disassembly and reassembly, and the metal powder for overlay is placed above the nozzle members (60 to 62). from the lower opening of the powder carrier gas supply path to the nozzle member (60~
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 powder carrier gas supply path outlet and each powder carrier gas flow The distance to the channel entrance often differs from channel to channel, and when the distance difference is large, metal powder flows relatively vigorously in a short-distance powder carrier gas channel, but in a long-distance powder carrier gas channel, metal powder flows relatively vigorously. It has been found that metal powder tends to accumulate in the gas flow path, and this accumulation further impedes the flow of the metal powder, further increasing the accumulation, and this vicious cycle eventually leads to clogging.

[0007]

[Means for Solving the Problems] Focusing on such a phenomenon, the present invention provides an arc hole (17) through which a plasma arc generated between the main electrode (1) and the base material (41) passes. is formed in the center of the arc hole (17), and a first set of powder particles, which are distributed at equal intervals around the central axis of the arc hole (17) and extend in a direction approaching the central axis and downward, allow the powder to pass through. A nozzle member (10) having a flow path (12); and a first set of powder flow paths (
12); a second set of powder channels (31) distributed at equal intervals around the central axis of the arc hole (17); In the deposition torch, the first set of powder flow channels (12
) is provided with a protrusion member (33) for positioning the nozzle member (10) and a recess (34) for receiving the protrusion member (33). ) is provided on the outer surface of the Note that symbols in parentheses indicate corresponding elements in the embodiments described later.

[0008]

[Operation] According to this, when the nozzle member (10) is attached to the torch, the projection member (33) and the recess (34) connect the second set of powder flow paths (31) and the arc. The first set of powder flow channels (12
) is distributed, the nozzle member (10) is positioned. Due to this positioning, the flow channels located at mutually symmetrical positions in the powder flow channels (31) of the first set are connected to the powder flow channels (12) of the second set.
) and receive the powder flow equally from each other.
The powder from the second powder flow path (31) is transferred to the first powder flow path (
12) When proceeding to step 12), the flow of powder becomes substantially equal in each flow path, and it is virtually impossible for powder to concentrate in one flow path and stagnate in another flow path. It disappears. Since such positioning of the nozzle member (10) is always performed reliably, the first set of powder flow paths (1) in the nozzle member (10)
Powder clogging in 2) is less likely to occur.

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

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of the tip of a plasma torch for powder overlay welding according to the present invention. Note that FIG. 1 shows different cross sections for the right half and the left half of the torch, and shows a cross section taken along the line A1-A1 in FIG. 3, which corresponds to the plan view of the torch. Referring to FIG. 1, a rod-shaped electrode 1 made of tungsten is arranged at the center of the torch, and this electrode 1 is fixed to the torch by a chuck 2. As shown in FIG. 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 in the center of the nozzle member 10. 20 is a centering stone for positioning the electrode 1 at the center of the member 10. Plasma gas is supplied from the outside through the space between the electrode 1 and the chuck 2, passes through the hole 8a formed in the support member 8, passes through the space between the electrode 1 and the centering stone 20, and is supplied to the centering stone. Through the hole 21 formed in the stone 20,
It is guided to the arc hole 17 of the nozzle member 10. This plasma gas is ionized by arc discharge between the electrode 1 and the base material 41 to form a high temperature plasma arc flow 43.

The powder and the powder carrier gas for transporting it are supplied from outside the torch, pass through the powder tube 7, and pass through two holes (powder carrier gas supply path) formed in the nozzle base 30.
31, and the plasma arc flow 4 through four holes (powder carrier gas flow paths) 12 formed in the nozzle member 10.
3 and is injected into it. The powder is melted by the heat of the plasma arc flow 43 and becomes molten metal 42.
and covers the welding surface on the base material 41.

The shielding gas 44 is injected through the space 6 between the nozzle cap 5 and the casing 3 so as to cover the plasma arc flow 43, thereby shielding the welding surface from the outside air. Moreover, in order to prevent overheating of the nozzle member 10,
Cooling water flows from the outside of the torch through the holes 32 to the nozzle member 1.
It is supplied to the groove portion 11 formed at 0.

FIG. 2 shows a longitudinal section of the plasma torch for powder overlay shown in FIG. 1, taken at a different angle from that shown in FIG. Note that this longitudinal section is shown in Figure 3, which corresponds to the torch plan view.
This is a cross section taken along line A2-A2. In FIG. 2, the nozzle stand 30
A pin 33 is fixed in the hole by press fitting, and the pin 3
3 protrudes into the nozzle member receiving hole of the nozzle stand 30. A groove 34 for receiving the tip of a pin 33 is cut into the nozzle member 10 at its upper end. The groove 34 is open on the upper end surface and 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 central axis of the arc hole 17 (electrode 1).

FIG. 3(a) shows an enlarged plan view of the nozzle member 10, and FIG. 3(b) shows a vertical sectional view taken along the line A3B-A3B in FIG. 3(a). Referring also to FIGS. 1 and 2, in this embodiment, four powder carrier gas channels 12 are formed in the nozzle member 10 at intervals of 90 degrees around the arc hole 17. The groove 34 is cut in the middle of two adjacent gas flow paths 12, that is, at a position forming an angle of 45 degrees with those gas flow paths 12. Two powder carrier gas supply passages 31 are formed symmetrically with respect to the electrode 1 in the nozzle stand 30 of the torch body, and the pin 33 connects the straight line Ls connecting the two gas supply passages 31 and the electrode. It is installed in a position and orientation perpendicular to the central axis of the device.

When the nozzle member 10 is connected to the nozzle stand 30, the nozzle 10 is inserted into the nozzle receiving hole at the center of the nozzle stand 30.
The upper end (sleeve) of the nozzle cap 5 is inserted and the nozzle cap 5 is screwed to some extent to the nozzle base 30. and nozzle 1
0 until its upper end surface touches the tip of the pin 30,
Next, the nozzle member 10 is rotated around the electrode 1 to form the groove 3.
4 to the tip of pin 30. As a result, nozzle member 1
0 can be pushed further, so push the nozzle member 10 further. As a result, the tip of the pin 33 enters the groove 34. Then, the nozzle cap 5 screwed to the nozzle stand 30 is tightened to tighten the nozzle member 10 to the uppermost position. Then, the cover 3 is attached to the nozzle stand 30 by screw connection. As a result, the nozzle member 10 shown in FIG. 3 is mounted on the nozzle stand 30 as shown in FIGS. 1 and 2.

In this state, the pin 33 of the nozzle base 30
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. 3(a): plan view and FIG. 4 (perspective view). In other words, the powder carrier gas supply path (
Four powder carrier gas flow paths (first set of powder flow paths) are arranged symmetrically with respect to the straight line Ls connecting the second set of powder flow paths) 31 and the center axis of the arc hole 17 (electrode 1). 12 are distributed. Note that there is a ring-shaped space between the lower opening of the powder carrier gas supply path 31 and the upper opening of the powder carrier gas flow path 12. In this state, the distance between the powder carrier gas flow path 12 and the powder carrier gas supply path 31 on the groove 34 side with respect to the straight line Ls, and the distance between the powder carrier gas flow path 12 on the opposite side of the groove 34 and the powder The distance to the carrier gas supply path 31 is equal. As a result, the powder carrier gas flows evenly into the gas flow path 12 on the groove 34 side and the gas flow path 12 on the opposite side of the groove 34, making it difficult for powder to stay in the powder carrier flow path 12. In other words, the flow path 12 is less likely to be clogged. Particularly in this embodiment, since there is one pair of powder carrier gas supply passages 31 and two pairs of powder carrier gas passages 12, all of the gas passages 12 are equidistant from supply passages 31. Therefore, the flow path 12
Highly effective in preventing clogging.

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

[0018]

Effects of the Invention In any case, according to the present invention, the powder flow path (31) of the second set of the torch main body and the central axis of the arc hole (17) are symmetrically connected to each other. Nozzle member (10
The nozzle member (10) is positioned to ensure that the first set of powder flow channels (12) of ) are always reliably distributed. With this positioning, the mutually symmetrical channels in the first set of powder flow channels (31) are equidistant from each of the second set of powder flow channels (12), and the powder is evenly distributed. When the powder from the second powder flow path (31) advances to the first powder flow path (12) under the body flow, the flow of the powder becomes substantially equal in each flow path, Powder concentrates in one channel and substantially no longer remains in another channel. Such a nozzle member (
10) is always reliably positioned, clogging of the powder in the first set of powder channels (12) within the nozzle member (10) is less likely to occur.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a main part of an embodiment of the present invention, and is a vertical cross-sectional view taken along the line A1-A1 in FIG. 3.

2 is a longitudinal sectional view of the main part of the above embodiment, and is a longitudinal sectional view taken along the line A2-A2 in FIG. 3, showing a different section from the section shown in FIG. 1. FIG.

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

[Fig. 4] Nozzle member 1 shown in Figs. 1, 2, and 3
0 is an enlarged perspective view of FIG.

FIG. 5 is a longitudinal sectional view of the tip of a conventional plasma powder overlay torch.

FIG. 6 is a longitudinal sectional view of the tip of another conventional plasma powder overlay 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 flow path 12: Powder carrier gas flow path (first set of powder flow path) 13
：Concave part
14: Inclined surface 17: Arc hole
20: Centering stone 21: Hole
30: Nozzle stand 31: Powder carrier gas supply path (second set of powder flow path) 33: Pin (projection member)
34: Groove (recess) 41: Base material
42: Molten metal 43: Plasma arc flow
44: Shield gas

Claims (1)

[Claims] Claim 1: An arc hole through which a plasma arc generated between the main electrode and the base material passes is formed in the center, and is distributed at equal intervals around the central axis of the arc hole. a nozzle member having a plurality of first sets of powder flow channels through which the powder passes, extending in a direction approaching and downward; and a nozzle member for supplying powder to the first set of powder flow channels from above; In a plasma powder overlay torch equipped with a plurality of second sets of powder flow channels distributed at equal intervals around the central axis of the arc hole, the second set of powder flow channels and the arc The torch body includes a protruding member for positioning the nozzle member and a recess for receiving the protruding member so that the first set of powder flow paths is distributed symmetrically with respect to the straight line connecting the central axis of the torch hole. and the other provided on the outer surface of a nozzle member.