JP2930914B2 - Laser seam welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a laser seam welding method, and more particularly to a laser seam welding method for welding a spacer used in a nuclear fuel assembly.

[0002]

2. Description of the Related Art In general, a plurality of spacers are attached to a nuclear fuel assembly so as to keep a constant interval between a plurality of fuel rods constituting the nuclear fuel assembly.

[0003] As shown in FIGS. 4 and 5, a spring 12 is attached to a plurality of cylindrical cells 11 having a predetermined length.
And tightened with a band-shaped band 13 from the outside of the plurality of cylindrical cells 11 and welded the contact portions between the cylindrical cells 11 and the cylindrical cells 11 and the contact portions between the cylindrical cells 11 and the bands 13. This is a connection structure.

The cylindrical cell 11 of such a spacer 10
In the welding of (1), a laser welding method in which a laser beam generated from a laser generating unit is condensed by a condenser lens and guided to a cylindrical cell 11 is generally adopted.

The laser welding method can be roughly classified into a laser spot welding method in which a laser beam is positioned in a cylindrical cell 11 and the laser beam is focused and irradiated, and a laser spot welding method in which the laser beam is focused and irradiated. And a laser seam welding method of relatively moving the laser beam and the optical axis of the laser beam for welding.

[0006]

The welding of the cylindrical cell 11 is, of course, free of welding defects. However, in order to guarantee a predetermined joint strength, the size of the welding nugget is specified and the welding quality is stable. You need to get

Therefore, the output of the laser beam must be strictly controlled, and this laser beam must be accurately positioned and irradiated on the cylindrical cell 11 by numerical control.

The cylindrical cell 11 of the spacer 10 has an outer diameter of 11 to 13 mm and a thickness of 0.5 to 0.7 m.
m is used, and the contact portions between the cylindrical cells 11 and the cylindrical cells 11 and the welded portions between the cylindrical cells 11 and the bands 13 are point contacts.

In order to accurately position and irradiate a laser beam focused on the contact portion, a laser spot welding method is often used among laser welding methods.

This laser spot welding method enables ideal welding if the shape and size of the cylindrical cells 11 are constant, but these cylindrical cells 11 usually have component tolerances in their outer diameters and the like. A position shift occurs, and the laser beam cannot be accurately applied to the contact portion.

An image processing device or the like is used to correct this positional deviation. However, this image processing device or the like not only requires a large amount of equipment cost but also requires a long time for correction, and requires a large number of welds like the spacer 10. However, there is a problem that it is not suitable for welding.

On the other hand, in the laser seam welding method, welding is performed while moving a laser beam. Therefore, even if there is some component tolerance, there is a margin in the cylindrical cell 11, so that there is little need to correct the positional deviation.

However, since each cylindrical cell 11 has a circular shape, the contact portions are in point contact with each other, and the gap between the welded portions increases as the distance from the contact portion increases. Irradiate the parts,
There was a problem that this would be damaged.

In addition, when the moving range of the laser beam is increased, the absorption rate of the energy of the laser beam, the heat capacity of the material, and the heat storage effect of the melting portion of the cylindrical cell 11 with the lapse of time are caused. In the latter half, the welded nugget becomes larger in shape than the first half of the cylindrical cell 11 and the shape of the weld nugget is deviated, and a symmetrical weld around the contact point is not formed. There is a problem that the dimensions are affected and that a spacer 10 having stable welding quality cannot be manufactured.

Accordingly, an object of the present invention is to provide a laser seam welding method capable of stabilizing the shape of a welding nugget and producing a spacer having stable welding quality without damaging parts of a spring in order to solve the above problems. It is assumed that.

[0016]

SUMMARY OF THE INVENTION The present invention provides a laser device having a laser generator controlled by a laser output controller, and a laser irradiator controlled by a laser beam movement controller and a laser beam focal length controller. Used, at least one is a cylindrical cell of the spacer, in the laser seam welding method of irradiating while moving the laser beam around the contact portion where the cylindrical cell contacts, input the shape data of the cylindrical cell, characteristic data One or more of the following: defining the welding range of the cylindrical cell from these input data, decreasing the output of the laser beam from the middle of this welding range, accelerating the moving speed, moving the focal length, etc. To make the shape of the nugget in the contact area where the cylindrical cell comes into contact Characterized in that to prevent damage to the ring.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the laser seam welding method according to the present invention will be described below with reference to the drawings.

The laser welding machine 20 used in the laser seam welding method of the present invention is provided with a laser generator 21 such as a CO ₂ laser or a YAG laser.

The laser generator 21 includes a laser irradiator 2
2 is attached, receives the laser beam generated from the laser generator 21, and irradiates the cylindrical cell 11 and the like while controlling the moving speed and the like of the laser beam.

The laser seam welding machine 20 is provided with a welding data input section 23 for inputting necessary data relating to the cylindrical cell 11.

The welding data input unit 23 is connected to an arithmetic processing unit 24 having a CPU and the like. The arithmetic processing unit 24 processes the input data and outputs a laser beam, a moving speed, a focal length, and energy in a welding range of the cylindrical cell 11. And so on.

The output of the laser beam is such that the size of the welding nugget of the cylindrical cell 11 is specified and stable quality is ensured, that is, from the first half of the welding start position having a relatively large gap. Data is output to be a normal output until the middle of the narrowing, but to a low output until the second half of the welding end position where the gap is gradually widened from the middle.

Similarly, the moving speed is the same as that of the cylindrical cell 1.
An output that regulates the size of the welding nugget 1 and ensures stable quality, that is, data that has a normal speed from the welding start position to the middle, but increases the speed from the middle to the welding end position. Is calculated.

Further, similarly, the focal length also determines the size of the welding nugget of the cylindrical cell 11 and an output which ensures stable quality, that is, a normal focus is obtained from the welding start position to the middle. Although the distance is used, data of the distance in which the focal point is enlarged from the middle to the welding end position is calculated.

Further, the energy is similarly set to an output that regulates the size of the welding nugget of the cylindrical cell 11 and ensures stable quality, that is, a normal output from the welding start position to the middle. Calculates low output data from the middle to the welding end position.

A laser output control unit 25, a laser beam moving speed control unit 26, a laser beam focal length control unit 27, and the like are connected to the arithmetic processing unit 24, and data such as the output of the laser beam, the moving speed, and the focal length are transmitted. The output of the receiving laser generator 21 and the laser irradiator 22 is controlled.

A support table 28 for supporting the laser seam welding machine 20 and the cylindrical cell 11 is provided with a processing table 29, and the laser seam welding machine 20 is positioned at a predetermined position of the cylindrical cell 11 on the support table 28 by numerical control. The laser beam is moved at a predetermined speed, and the laser beam is always sequentially opposed to the cylindrical cell 11.

A case where the cylindrical cell 11 is welded by using such a laser seam welding machine 20 will be described.

For convenience of explanation, the moving speed of the laser beam,
A method of welding the spacer 10 that controls the output of the laser beam while fixing the focal length, energy, and the like, regulates the size of the welding nugget, and ensures stable quality will be described.

First, the shape data of the cylindrical cell 11 to be welded is input to the welding data input unit 23. As shown in FIG. 3, the shape data includes data that does not damage the spring 12 due to a laser beam leaking from between the cylindrical cells 11 having an outer diameter of 11 to 13 mm. .8 mm, ie 1.6 m
Data for determining the welding range of m is also included. In addition, characteristic data such as the heat capacity of the material of the cylindrical cell 11, the heat storage effect of the molten portion over time, and the amount of melted material are also input to the welding data input unit 23.

Each of these input data is sent to an arithmetic processing section 24 to execute arithmetic processing, and as shown in FIG.
1, a welding range D centering on the center portion which is the contact portion, and the output, the moving speed, and the focus of the laser beam from the welding start position D1 in the first half to the welding end position D2 in the second half via the contact portion D0 in the welding range D. Calculate data such as distance and energy.

This data is sent to the laser generator 25 via the laser output controller 25 to generate a laser beam output in the welding range.

This data is sent to the laser irradiation unit 22 via the laser beam moving speed control unit 26, and the laser beam moving speed in the welding range is extracted.

Further, this data is sent to the laser irradiation unit 22 via the laser beam focal length control unit 27, and a distance for determining the position of the laser beam focal point in the welding range is extracted. Further, such an operation is performed on the energy of the laser beam.

Further, the processing table 29 is numerically controlled, and the laser seam welding machine 20 is arranged on the welding start position D1 of the cylindrical cells 11, 11.

After performing such processing and operation, when a laser beam is generated from the laser generating unit 21, the laser beam output becomes a normal output during the distance X1 from the welding start position D1 to the middle, but from the middle. The output is low until the distance X2 to the welding end position D2.

With this output, laser seam welding is performed by a normal laser beam output from the portion where the gap in the first half of the cylindrical cell 11 is relatively wide to the middle, and the portion from the middle to the second half where the gap is relatively wide is low. Since the laser seam welding is performed by the laser beam output, the heat storage effect and the process of solidification shrinkage are made uniform over the entire welding range D, and a stable welding nugget with no dimensional error is formed.

When the welding of one welded portion is completed, the processing table 29 is controlled and the laser beam is applied to the next cylindrical cell 11.
Is placed on the welding start position D1 and is welded by a similar method.

By performing such welding, the welding of each cylindrical cell 11 becomes uniform, and the spacer 1 having no dimensional error.
0 can be produced. Further, in this welding, since the welding range is restricted by the shape of the cylindrical cell 11 and the like, the laser beam does not leak to the spring 12 through the space between the cylindrical cells 11 and 11 and does not damage it.

Furthermore, since this welding is performed by seam welding, the welding can be performed without correcting the dimensional tolerance of the cylindrical cells 11, and a large number of spacers can be manufactured in a short time.

Next, a laser welding method for controlling the moving speed, focal length, energy, etc. of the laser beam to form a welding nugget of stable quality for the cylindrical cells 11, 11 is almost the same as that for controlling the laser beam output. Can be done.

The basic operations of these laser welding methods are almost the same as those for controlling the output of the laser beam.

When the data processed by the arithmetic processing unit is received by the laser beam moving speed control unit 26, the laser beam moving speed control unit 26 generates a laser beam moving speed control signal. This moving speed control signal is transmitted to the laser irradiation unit 22.
Starting position D by rotating a mirror (not shown)
The moving speed of the laser beam at a distance X1 from 1 to the middle is a normal moving speed, for example, 100 to 600 mm /.
min, and the moving speed at a distance X2 from the middle to the welding end position D2 is three times the normal moving speed, for example, 600 to 3600 mm / min.

Here, the laser beam is moved by the laser irradiating section.
It is also possible to control the movement amount.

By welding the cylindrical cells 11, 11 and the like according to the moving speed of the laser beam, it is possible to manufacture a spacer having a welding nugget of stable quality over the entire welding range.

Further, when the focal length of the laser beam is adjusted and controlled, similarly, when the laser beam focal length control unit 27 receives the data processed by the arithmetic processing unit 24, the laser beam focal length control unit 27 transmits the data. Generate a distance control signal. The focal length control signal is sent to the laser irradiating unit 22 to adjust the focal length of the condenser lens (not shown) so that the focal length at the distance X1 from the welding start position D1 to the middle is adjusted to the cylindrical cells 11 and the welding is completed from the middle. It is positioned so that the focal length at a distance X2 to the position D2 is separated from the welded portion.

By welding the cylindrical cells 11 and 11 by controlling the focal length of the laser beam, it is possible to manufacture a spacer having a welding nugget of stable quality over the entire welding range.

In the same manner, when controlling the energy of the laser beam, by controlling the shutter (not shown) of the laser irradiation unit 22 to weld the cylindrical cells 11 and 11 in a similar manner, welding of stable quality can be performed over the entire welding range. A nugget-formed spacer can be manufactured.

In the above embodiment, the output of the laser beam,
Although the moving speed, the focal length, and the like are individually controlled, more precise control can be performed by controlling them simultaneously.

In the above embodiment, the case where the cylindrical cells 11, 11 and the like of the spacer are welded has been described. However, it is needless to say that the present invention can be applied to welding of the cylindrical cells 11, 11 and the band 13, precision equipment, and the like. .

[0051]

According to the present invention, at least one of a laser device having a laser generator controlled by a laser output controller and a laser irradiator controlled by a laser beam movement controller and a laser beam focal length controller is used. Is a cylindrical cell of the spacer, and in the laser seam welding method of irradiating the laser beam while moving the laser beam around the contact portion where the cylindrical cell comes into contact, the shape data and characteristic data of the cylindrical cell are input, and these inputs are performed. The welding range of the cylindrical cell is specified from the data, and the output of the laser beam is reduced from the middle of this welding range, the moving speed is accelerated, and the focal length is moved. The shape of the nugget in the contact area where the cylindrical cell comes into contact is made symmetrical, and the spring provided in the cylindrical cell is damaged. It is so arranged to stop, it can be secured to the stable quality as to form a weld nugget of the defined shape of the welded portion such as the cylindrical cell.

Therefore, not only welding defects are eliminated but also joint strength can be guaranteed, and the spring of the cylindrical cell is not damaged by the laser beam.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of a laser welding machine according to the present invention.

FIG. 2 is an explanatory view showing an example of a case where a cylindrical cell or the like is laser-welded.

FIG. 3 is a characteristic diagram showing an example of a damage occurrence rate of a spring by a laser beam.

FIG. 4 is a plan view of a commonly used spacer.

FIG. 5 is a side view of the spacer of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Spacer 11 Cell 12 Spring 13 Band 20 Laser seam welding machine 21 Laser generation part 22 Laser irradiation part 23 Welding data input part 24 Operation processing part 25 Laser output control part 26 Laser beam moving speed control part 27 Laser beam focal length control part 28 Support Table 29 Processing table

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23K 26/00 G21C 3/34

Claims (1)

(57) [Claims] 1. A laser device having a laser generator controlled by a laser output controller and a laser irradiator controlled by a laser beam movement controller and a laser beam focal length controller, at least one of which is a spacer. In a laser seam welding method in which a laser beam is irradiated while moving a laser beam around a contact portion where the cylindrical cell comes into contact, shape data and characteristic data of the cylindrical cell are input, and a cylinder is obtained from the input data. While controlling the welding range of the cylindrical cell and reducing the output of the laser beam from the middle of this welding range, accelerating the moving speed, moving the focal length, etc., one or more of the cylindrical cells are controlled. The shape of the welding nugget at the contacting part that makes contact is made symmetrical and the spring provided in the cylindrical cell is prevented from being damaged. A laser seam welding method.