Fluid sprinkling – spraying – and diffusing – Motor or spray fluid operated continuously moving discharge... – Spray fluid operated
Reexamination Certificate
2002-07-01
2003-10-21
Maust, Timothy L. (Department: 3751)
Fluid sprinkling, spraying, and diffusing
Motor or spray fluid operated continuously moving discharge...
Spray fluid operated
C239S225100, C239S079000, C239S083000, C118S323000, C118S217000
Reexamination Certificate
active
06634571
ABSTRACT:
RELATED APPLICATIONS
This application is the national phase of PCT application PCT/JP01/00589, filed Jan. 29, 2001, which designated the United States but was not published in English, the disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to a thermal spraying torch, which is used in the case of carrying out a surface treatment using a thermal spray material heated and fused by a plasma forming gas or combustion gas. In particular, the present invention relates to a thermal spraying torch, which is suitable for carrying out a surface treatment with respect to an inner surface of pipes, cylinders and the like.
BACKGROUND ART
Pipes such as those for cooling medium used in boilers and power generators, pipes connecting chemical reaction equipment, pipes for delivering chemicals and carrying special materials are used under severe conditions; as a result, these pipes are easy to corrode. For this reason, the inner surface of pipes must receive a suitable surface treatment so that corrosion resistance can be improved.
Likewise, there is a great need for carrying out the surface treatment with respect to each inner surface of many cylinders
91
formed in a cylinder block
90
as shown in FIG.
12
. The cylinder block
90
shown in
FIG. 12
is used for an engine of automobile, for example. In this case, there is a need to reduce the entire weight of the automobile; for this reason, the cylinder block
90
is formed of a light aluminum alloy. An iron coating film must be formed on the inner surface of each cylinder
91
so that the inner surface of the cylinder can withstand repeated sliding contact of the pistons.
Plating may be used as the surface treatment with respect to the inner surface of the pipes and the cylinder
91
. However, in this case, depending on the plating technique, merely a thin coating of film is formed, and further, in the case of plating a large-sized work piece, such as the cylinder block
90
, considerably large plating equipment is required. In view of the above circumstances, so-called “thermal spraying technology” has attracted special interest recently as a technology capable of creating the required coating thickness comparatively easily.
However, the conventional thermal spraying technology is employed in cases where a thermal spray work piece is a flat shape as disclosed in JP 61-149264 A (Unexamined Patent Publication (Kokai) No. TOKKAISHO 61-
149264)
and JP 61-149265 A (Unexamined Patent Publication (Kokai) No. 61-149265), or in cases where the work piece is a large curved shape as disclosed in JP 56-100666 (Unexamined Patent Publication (Kokai) No. 56-100666). Thus, there has been almost no thermal spraying technology for carrying out a surface treatment with respect to a cylindrical inner surface such as the inner surface of pipes or the inner surface of a cylinder
91
.
In view of the above circumstances, the present inventor has already proposed a thermal spraying torch, which is suitable for carrying out thermal spraying with respect to the inner surface of the pipe and the cylinder
91
in JP 5-29092 B (Examined Patent Publication (Kokoku) No. 5-29092). The thermal spraying torch disclosed in the above Publication is provided with a rotatable discharge member attached to the distal end portion, and further, the discharge member is formed with a pressure-receiving portion at the outer periphery. A gas is sprayed onto the pressure-receiving portion, and thereby, the entirety of the discharge member can be rotated. Of course, a droplet
81
is jetted from the discharge member. When being jetted, the droplet
81
is radially discharged, and thereby, thermal spraying is carried out with respect to the inner surface of the pipe and the cylinder
91
by the rotation of the discharge member and the radially discharged droplet
81
.
Thereafter, the present inventor has studied the thermal spraying torch proposed in the above JP 5-29092 B (Examined Patent Publication (Kokoku) No. 5-29092). As a result, the present inventor has discovered that in the known thermal spraying torch a uniform coating
82
is difficult to form. The present inventor discovered that the discharge member does not reach a sufficiently high rotational speed (3,000 rpm or more), which he found was required for forming a uniform sprayed coating film
82
on the cylinder inner surface of a cylinder
91
. The present inventor then investigated the reasons why the required rotational speed was not obtained. Although not wishing to be bound, the present inventor considers that in the thermal spraying torch proposed in JP 5-29092 B (Examined Patent Publication (Kokoku) No. 5-29092), in order to spray a gas onto the pressure receiving portion formed at the outer periphery of the discharge member, the main body positioned outside the discharge member must be formed with a first passage for supply of the gas. However, due to the design, the inner diameter of the first passage cannot be set too large, and thereby, the amount of gas supplied to the outer periphery of the discharge member is limited. As a result, the discharge member cannot attain a satisfactory, desired high rotational speed, which denies the regular forming of a uniform sprayed coating film
82
.
Of course, in cases where a material such as zinc having a relatively low melting point is used as a thermal spray material, the high rotational speed as described above is not required. Further, in order to prevent mechanical damage to this type of rotary torch, there are some cases where it is desired that the rotational speed is as low as possible.
Further, the present inventor has conducted various studies as to determine the setting of the rotational speed of the discharge member in the ranges of 800 to 6,000 rpm and as a result, the present invention has been made.
SUMMARY OF THE INVENTION
In the Summary and in the “Best Mode for Carrying out the Invention” like reference numerals are used in describing constituent components or process steps included in first and second aspects of the present invention.
An object of the present invention is to provide a thermal spraying torch
100
, which can set a rotational speed of discharge member for radially discharging droplets
81
to a range from 800 to 6,000 rpm, and can carry out thermal spraying with respect to the inner surface of a pipe or a cylinder
91
.
Another object of the present invention is to provide a thermal spraying torch
100
, which can set a rotational speed of discharge member for radially discharging a droplet(s)
81
to a suitable value, e.g., 3,000 rpm within a range from 800 to 6,000 rpm, and can carry out thermal spraying with respect to the inner surface of a pipe or a cylinder
91
, and further, can protect bearings supporting the discharge member so that high durability can be obtained.
In order to achieve the above objects, according to a first aspect of the invention, the present invention provides a thermal spraying torch
100
that is capable of successively supplying a thermal spray material
80
, which can be heated and fused by a plasma forming gas formed by an arc generated between electrodes contained in an outer cylinder
10
or by a combustion gas supplied passing through an outer cylinder
10
and burned under high temperature state, and spraying the thermal spray material
80
via a nozzle
40
using the plasma forming gas or the combustion gas so that a droplet(s)
81
can be formed. The thermal spraying torch
100
further includes a rotating discharge member
60
, which is contained at a forward portion of the nozzle
40
and has a droplet passage
61
for the droplet(s)
81
at the center so that the droplet(s)
81
can be jetted together with the plasma forming gas or the combustion gas. The discharge member
60
is formed with a projection
63
, which changes a discharge direction of a droplet(s)
81
at the center of the distal end portion, and is formed integrally with a plurality of arm members
65
, which are projected from the discharge member
60
and arranged in an ai
Flynn Amanda
Maust Timothy L.
Shimazu Kogyo Yugenkaisha
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