JPH0422679B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a flame welding device that uses a laser beam, and more specifically, the present invention relates to a flame welding device that uses a laser beam, and more specifically, a beam welding device that gradually approaches one side of a metal material, such as a steel strip, and The present invention relates to a seam welding device that irradiates a laser beam from between metal materials in a direction that coincides with the seam weld line after welding when seam welding.

(Prior Art) Conventionally, butt welding of the sides of metal materials using a laser beam utilizes the "keyhole" phenomenon described below.

In other words, the laser beam is irradiated perpendicularly to the surface of the material to be welded, and the energy is accumulated in a thin layer of the material, where the surface of the material is intensely heated and collapses, resulting in what is called a "keyhole". A recess is formed and completely absorbed.

For beam powers of several kilowatts, the "keyhole" is several millimeters deep.

The metal vapor pressure maintains the cavity relative to the static pressure of the liquid metal surrounding the cavity. With appropriate relative movement between the beam and the material to be welded, the cavity becomes physically stable and moves through the material, first by welding and then by solidification.

Because the field depth in welding engineering is relatively shallow, multiple reflections and partial absorption processes allow the beam to travel into the cavity without further penetration until all beam power is attenuated.

At a given power level, weld penetration is inversely proportional to welding speed. Similarly, at a constant speed, penetration is directly related to power.

When the welding speed is reduced at a constant power level, the extent of the weld metal area surrounding the cavity is expanded in proportion to the increased energy storage per unit length.

Eventually, the metal vapor pressure becomes insufficient to counteract the dynamic pressure of the liquid metal, and the deep penetration cavity collapses. Under these conditions, a sharp decrease in penetration occurs, resulting in a nearly hemispherical fusion characteristic of surface energy input.

Therefore, the conditions just before cavity collapse serve to limit the maximum penetration of the weld.

The welding method using the above-mentioned "keyhole" is a welding process, and in this welding process, penetration and heat affected zone (hereinafter referred to as HAZ) are functions of laser power and welding speed.

At a constant laser power, penetration can be increased by decreasing the welding speed until maximum penetration is achieved. If the speed is slower than this, the weld width and HAZ will increase while the penetration remains constant, resulting in only poor quality welds.

In particular, when seam welding relatively thin materials using a low-power laser with laser beam welding, the main purpose is to weld in a narrow weld area, so it is extremely difficult to weld a wide weld area. It's inconvenient.

Therefore, when seam welding is performed by gradually bringing one side of a metal material such as a steel band closer together and butting it together,
For example, Japanese Patent Application Laid-Open No. 56-114590 discloses a seam welding method that utilizes the skin effect without the so-called "keyhole" phenomenon by irradiating a laser beam between metal materials in a direction that matches the seam weld line after welding. There is a welding method as described in a publication (hereinafter simply referred to as a prior example).

(Problems to be Solved by the Invention) Since the preceding example merely shows the principle of welding, there are various problems to be solved in actual implementation.

(Means for Solving the Problems) In view of the above-mentioned problems, the present invention involves pressing a strip-shaped first metal material and a second metal material from the sides so that the side edges of the two materials are mutually pressed. a pair of pinch rollers that are brought into contact with the above-mentioned materials; a pair of delivery/tension rollers that pinch and press the above-mentioned both materials from the plate thickness direction on the front side of the above-mentioned pinch rollers when viewed in the longitudinal direction of movement of the above-mentioned both materials; and a device for irradiating a laser beam to the joining point of the two materials from a rear position as viewed in the direction of movement, the seam welding apparatus comprises: A pair of alignment rollers are provided to align both materials in the thickness direction by simultaneously pinching and pressing both materials from the thickness direction, and each of the alignment rollers is provided with a small diameter neck through which the laser beam can freely pass. be.

(Example) In the example shown in FIG. 1, the metal materials to be welded are materials 1 and 3, such as flexible steel strips.
and are abutted at an angle θ at a junction point in the illustrated X-Y plane. The laser beam 5 is optically shaped and irradiated along the Y axis so that it lies in the same straight line as the weld seam.

Viewed in the direction of longitudinal movement of the materials 1, 3, in front of the joining point where the laser beam 5 causes melting of the edges of the materials 1, 3, both materials 1, 3 are moved in the X-axis direction. pinch rollers 9 and 1
1 is provided.

The pinch rollers 9 and 11 have the function of appropriately aligning the materials 1 and 3 and controlling the gap.

The laser beam 5 has a Gaussian distribution in the X-Y plane as shown in Figure 2, and a third distribution in the X-axis direction.
A special optical geometry is desirable to obtain a nearly linear energy source exhibiting a uniform energy density as shown.

This is formed through, for example, a cylindrical lens. This laser welding technique is superior to conventional techniques that utilize a laser beam directed perpendicularly to the weld seam.

This is because the new process provides uniform heat input along the Z-axis, resulting in a uniform transverse weld cross-section with excellent mechanical strength.

Melting in solid phase welding occurs only on the skin of the material, so it can be confined to very narrow welds and HAZs.

Additionally, if solid state welding is desired, clamping forces are applied to squeeze out weld metal oxides and other surface impurities, resulting in a weld free of inclusions and impurities.

This laser welding obtains penetration by the unique shape of the laser beam with respect to the material, and does not rely on the so-called "keyhole" phenomenon.

The laser beam is simultaneously and uniformly supplied along the thickness direction of the material to be welded. In this way, "penetration" depends on focusing optics,
Laser power is not dependent on welding speed.

On the other hand, the laser power controls the welding speed and HAZ.

Welding with a laser beam collinear with the direction of the weld seam is applied when continuous welding of flexible materials is required. The material must be thin and sufficiently flexible to allow "Y-shaped" feeding.

The structure of the apparatus will be explained based on the drawings. Guide rollers 13, 15 and 17, 19 continuously feed flexible materials 1 and 3 at the same speed.

Two sets of feed rollers consisting of guide rollers 13, 15, 17, and 19 align the steel strips 1 and 3 in the XY plane and control the angle θ at the apex. It also functions as a tension control means for the pinch rollers 9 and 11.

The alignment rollers 23, 25 are provided with a small diameter neck 27, 29 in the center of each roller to allow the laser beam 5 to pass through and reach the junction.

The above-mentioned alignment rollers 23 and 25 strictly control the feeding speed of the two materials 1 and 3, and finally align these materials.

The distance from the apex of the pinch rollers 9, 11 and the tightening force are variable in order to control the welding interval. As already mentioned above, even if the gap is zero, solid phase welding is possible by applying sufficient clamping force.

The welded material finally passes through delivery/tension rollers 31 and 33 provided in front of the pinch rollers 9 and 11, and is fed into a coiler (not shown). Delivery and tension roller 31, 3
3 feeds out the material at the same speed as the feeding speed of the alignment rollers 23 and 25, which also serves to adjust the tension of the steel strip during welding.

The welded material is finally wound around a coiler (not shown).

It goes without saying that the following parameters must be controlled.

(a) Laser beam power (b) Laser beam shape (c) Laser beam focal length (d) Feeding speed of the material to be welded (welding speed) (e) Vertex angle θ (f) Tension and alignment state of the material (g ) Clamping force The laser beam has a substantially uniform density along the thickness of the material and its shape is given using a suitable optical system so that it is equal to the thickness of the material at the focal point.

Thus, the outer shape of the laser beam in the X-Y plane is as shown in the figure. That is, in FIG. 3, b is the thickness of the material and a is made as small as possible. FIG. 2 also shows an X-Y cross-section of the beam.

Parameters must be controlled so that melting occurs uniformly along the thickness at the edges of the material.

Furthermore, by controlling the welding speed for a constant laser power, the skin depth of the weld can be controlled.

Welding requires a skin depth on the order of 0.1 mm, and solid phase welding requires a smaller skin depth.

It is desirable that sufficient tension be maintained in the material between the alignment roller and the delivery and tension roller to keep the material from wrinkling or misalignment.

(Effects of the Invention) As can be understood from the above description of the embodiments, the present invention provides a first metal material 1 in the form of a strip.
a pair of pinch rollers 9, 11 that pinch and press the second metal material 3 from the sides to bring the side edges of the two materials 1, 3 into contact with each other; and a pair of pinch rollers 9, 11 that move the materials 1, 3 in the longitudinal direction. The above pinch rollers 9, 1 when viewed in the direction
A pair of delivery/tension rollers 31 that pinch and press both materials 1 and 3 from the plate thickness direction on the front side of 1;
33, and a device for irradiating a laser beam 5 from a rear position to the joining point of the two materials 1 and 3 as seen in the direction of movement of the two materials 1 and 3, , 3, a pair of aligning rollers 23, which simultaneously clamp and press both materials 1, 3 from the thickness direction to align both materials 1, 3 in the thickness direction, at a rear position of the joining point when viewed in the moving direction of the materials 1, 3; 25, and each of the alignment rollers 23, 25 is provided with small diameter neck portions 27, 29 through which the laser beam 5 can freely pass through.

As is clear from the above configuration, in the present invention, when the side edges of both materials 1 and 3, such as steel strips, are brought into contact and seam welded, both materials 1 and 3 are A pair of alignment rollers 23 and 25 are provided at the rear of the joining point of materials 1 and 3 to align them in the thickness direction by pinching the materials 1 and 3 from the thickness direction. The alignment in the plate thickness direction at the joint point is performed accurately, and for example, when the thicknesses of both materials 1 and 3 are equal, there is no difference in level at the joint point, and accurate welding can be performed. It is.

Further, in the present invention, the alignment roller 2
3 and 25 are provided with small diameter necks through which the laser beam 5 can freely pass through, so when the laser beam 5 is irradiated from the rear position to the joining point of both materials 1 and 3,
The alignment rollers 23 and 25 do not get in the way, and even when the alignment rollers 23 and 25 are close to the bonding point, the laser beam 5 can be easily irradiated from the rear to the bonding point. It is something that can be done.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an embodiment of the present invention, Fig. 2 is a welding energy distribution diagram on the X-Y cross section of Fig. 1, and Fig. 3 is a welding energy distribution diagram on the Z-X cross section of Fig. 1. It is. (Explanation of symbols representing main parts of drawings), 1, 3
...Material, 5...Laser beam, 9,11...Pinch roller, 23,25...Alignment roller, 27...
...Neck, 31, 33...Feeding and tension roller.

Claims (1)

[Claims] 1 Band-shaped first metal material 1 and second metal material 3
a pair of pinch rollers 9, 11 that press the materials 1, 3 from the sides to bring the side edges of the materials 1, 3 into contact with each other;
and a pair of delivery/tension rollers 31, 33 which pinch and press both the materials 1, 3 from the plate thickness direction on the front side of the pinch rollers 9, 11 when viewed in the direction of movement in the longitudinal direction of the materials 1, 3. , a device for irradiating a laser beam 5 to the joining point of the two materials 1, 3 from a rear position as seen in the direction of movement of the two materials 1, 3; A pair of alignment rollers 23 and 25 are provided at a rear position of the joining point when viewed in the direction of movement of the rollers, for simultaneously pressing the two materials 1 and 3 from the thickness direction and aligning the materials 1 and 3 in the thickness direction. The seam welding apparatus is characterized in that each of the alignment rollers 23 and 25 is provided with small diameter neck portions 27 and 29 through which the laser beam 5 can freely pass through.