Electric heating – Metal heating – By arc
Reexamination Certificate
2001-08-10
2003-08-19
Heinrich, Samuel M. (Department: 1725)
Electric heating
Metal heating
By arc
Reexamination Certificate
active
06608281
ABSTRACT:
The entire didclosure of Japanese Patent Applicaiton No. 2000-242367 filed on Aug. 10, 2000 including specification, claims, drawings and summary is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a laser beam machining head and a laser beam machining apparatus equipped with it, which are useful when applied in performing laser beam welding and arc welding at the same time.
2. Description of the Related Art
Among welding techniques for joining metals together are laser beam welding and arc welding. Laser beam welding is performed using a CO
2
laser oscillator or a YAG laser oscillator. CO
2
laser light has to be mirror transmitted, and thus its adjustment is laborious, while YAG laser light can be transmitted by an optical fiber. Under these circumstances, expectations are rising for laser beam welding using a YAG laser oscillator. Arc welding comes in types, including gas shielded consumable electrode arc welding (GMA welding) such as MIG welding, and gas shielded non-consumable electrode arc welding such as TIG welding.
Since laser light is condensed by optical instruments to give a high energy density, laser beam welding achieves deep weld penetration in a narrow range of melting. With arc welding such as GMA welding (MIG welding, etc.) or TIG welding, on the other hand, the arc spreads in a relatively broad range, thus performing welding of a wide bead range, and enabling welding with a high groove tolerance. In recent years, therefore, methods for simultaneously performing laser beam welding and arc welding have been studied in attempts to carry out welding with a wide welding range and a deep weld penetration.
A laser beam machining head, which performs laser beam welding and arc welding simultaneously, has a configuration, for example, disclosed in Japanese Unexamined Patent Publication No. 1998-216972. As shown in
FIG. 11
, this laser beam machining head performs laser beam welding and arc welding by applying laser light
3
from a laser beam welding head
2
to a portion
1
a
, to be welded, of a base material
1
, and simultaneously applying an arc discharge from an electrode
5
of a GMA welding head
4
, while jetting a shielding gas at the portion
1
a
from a gas jet nozzle
6
. However, this laser beam machining head is large in size as a whole, since the laser beam welding head
2
and the GMA welding head
4
are independent in the laser beam machining head. Moreover, it is tiresome to keep the relative positional relationship between the laser beam welding head
2
and the GMA welding head
4
always constant in response to a change in the welding position or the welding posture. Thus, the laser beam machining head is not suitable, particularly, for three-dimensional machining by a robot.
The inventors of the present invention proposed in Japanese Unexamined Patent Publication No. 1999-156573 a laser beam machining head capable of solving the above-described problems. In this laser beam machining head, as shown in
FIG. 12
of the present drawings, laser light
12
transmitted by an optical fiber
11
is reflected by a convex roof mirror
13
and a concave roof mirror
14
, and divided thereby into two divisional beams, a first divisional laser beam
12
a
and a second divisional laser beam
12
b
, with a space portion
17
being formed therebetween. These divisional laser beams
12
a
and
12
b
are focused by a focusing lens array
15
onto a portion to be welded. The concave roof mirror
14
and the focusing lens array
15
are perforated, at the center thereof, with through-holes
14
a
and
15
a
, respectively. An electrode holding pipe
16
for holding an arc electrode, such as a TIG electrode or a GMA electrode, is inserted through the through-holes
14
a
,
15
a
, whereby the arc electrode held by the electrode holding pipe
16
is located in the space portion
17
between the divisional laser beams
12
a
and
12
b
and rendered coaxial with these laser beams. With the above-mentioned conventional coaxial laser beam machining head, the through-holes
14
a
and
15
b
are provided in the concave roof mirror
14
and the focusing coaxial arrangement takes much time, effort and expense, and the sites of the through-holes
14
a
,
15
b
are easily damaged. Furthermore, the convex roof mirror
13
and the concave roof mirror
14
are used to divide the laser light
12
into two beams, but these concave and convex roof mirrors
13
and
14
are very expensive.
SUMMARY OF THE INVENTION
The present invention has been accomplished to solve the above problems, and its object is to provide a coaxial laser beam machining head which is small in size, free from the risk of damaging optical instruments, and inexpensive, and a laser beam machining apparatus having this head.
A laser beam machining head, as a first aspect of the present invention for attaining the above object, comprises:
one collimating optical system for making laser light into a parallel beam;
a first reflecting mirror for reflecting part of the laser light made into the parallel beam by the collimating optical system to divide the laser light into two beams, a first divisional laser beam and a second divisional laser beam;
a second reflecting mirror for further reflecting the first divisional laser beam reflected by the first reflecting mirror to form a space portion between the first divisional laser beam and the second divisional laser beam;
one focusing optical system for focusing the first divisional laser beam and the second divisional laser beam onto a portion to be machined; and
a tip machining portion of machining means disposed in the space portion between the first divisional laser beam and the second divisional laser beam coaxially with the laser beams.
The above laser beam machining head of the first aspect is very small in size, inexpensive, and free from the risk of damage to the optical instruments, in comparison with the conventional laser beam machining head. This laser beam machining head is so small in size that it can be easily mounted, for example, to a multi-axis NC robot. Moreover, the tip machining portion of the machining means and the laser light (the first and second divisional laser beams) are coaxial. Thus, the laser beam machining head can be easily positioned and moved to an arbitrary position by the multi-axis NC robot, and three-dimensional machining can be performed with ease. Also, if the tip machining portion of the machining means is a GMA electrode, coaxial welding by this GMA electrode and the laser light makes welding at a very high speed possible. In addition, irradiation with laser light can stabilize an arc. Thus, welding of an SUS material or a high Cr material in a pure Ar gas atmosphere becomes possible, without the use of a special wire.
A laser beam machining head as a second aspect of the invention is the laser beam machining head of the first aspect, wherein
the second reflecting mirror is rendered normally and reversely rotatable, whereby spacing between a focused tip of the first divisional laser beam and a focused tip of the second divisional laser beam is adjustable.
According to the laser beam machining head of the second aspect, the rotation angle of the second reflecting mirror is set as desired to widen the spacing between the focused tip of the first divisional laser beam and the focused tip of the second divisional laser beam to a suitable degree, whereby a base material with a broad gap width can be welded.
A laser beam machining head as a third aspect of the invention is the laser beam machining head of the first aspect, wherein
the first reflecting mirror is rendered movable, whereby the division ratio for the first divisional laser beam and the second divisional laser beam can be adjusted, and the second reflecting mirror is rendered normally and reversely rotatable, whereby the spacing between the focused tip of the first divisional laser beam and the focused tip of the second divisional laser beam can be adjusted.
According to the laser beam machi
Akaba Takashi
Fujie Daijiro
Hashimoto Yoshio
Ishide Takashi
Watanabe Masao
Birch & Stewart Kolasch & Birch, LLP
Heinrich Samuel M.
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