JP2017205788A - Laser welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly and evenly move a beam spot over the whole bead surface at a high speed.SOLUTION: A beam spot 24 is randomly vibrated in a constant width by a vibration motor 32. A movable space of a lens frame 28 is defined within a constant range, and is supported by a support medium 30. A lens is vibrated in a reference plane perpendicular to an optical axis 25 of laser beam 16, and further, is vibrated also in a direction parallel to the optical axis 25. Because the beam spot is vibrated by the vibration motor 32, the beam spot is randomly vibrated in the movable space at a high speed. As a result, the beam spot 24 can be evenly moved at a weld part thereby enabling weldment of a high quality. An amplitude and a vibration frequency of the beam spot 24 can be easily optimized, whereby an inexpensive and robust device can be realized.SELECTED DRAWING: Figure 1

Description

  The present invention relates to welding performed by irradiating an object with laser light, and more particularly to a miniaturized laser welding apparatus suitable for welding work with a processing head supported by hand.

  The laser welding apparatus irradiates a welding portion of an object with a laser beam to melt and fuse the corresponding portion. In a laser welding apparatus, a laser beam is collected on a welding portion by a condenser lens to concentrate energy. For example, Patent Document 1 discloses a technique for obtaining a wide bead surface by rotating a beam spot of a laser beam with a predetermined radius at a welded portion. With such a technique, the welded portion is uniformly heated and high-quality welding is possible.

Japanese Patent Laying-Open No. 2015-205279

The known prior art has the following problems to be solved.
In the above-mentioned Patent Document 1, a laser beam condensing lens provided in a machining head is decentered and rotated. As a result, the beam spot rotates with an eccentric width. When the machining head is moved along the welded part while rotating the beam spot, a bead surface having a predetermined width can be formed.
For high-quality welding, we want the beam spot to run as uniformly as possible over the entire bead surface. For this, it is preferable to rotate the lens as fast as possible. However, since a bearing cannot be provided on the optical path of the lens, there is a limit in speeding up the mechanism. In some cases, the width of the bead surface may be increased or decreased depending on the structure or physical properties of the welding object. This can be achieved by shifting the center of rotation of the lens, but the mechanism is relatively complicated. The present invention has been made to solve the above problems.

  The following configurations are means for solving the above-described problems.

<Configuration 1>
A condensing lens for narrowing the laser beam to the welding surface;
A lens folder integrated with the condenser lens;
A support base that sets a movable region so that the lens folder can be freely moved by a certain width within a reference plane perpendicular to the optical axis of the laser beam;
A laser device comprising: a vibrating body that is fixed to the lens folder and vibrates and moves the lens folder so as to vibrate randomly within the movable region.

<Configuration 2>
The support has a movable region set so that the lens folder can be moved by a certain width in a direction parallel to the optical axis of the laser beam in addition to the movement in the reference plane. The laser apparatus according to 1.

<Configuration 3>
In the configuration 1 or 2, the vibration body is a vibration motor having a rotational drive shaft having an eccentric center of gravity, and is fixed to the lens folder so as to transmit only the generated vibration to the lens folder. The laser device described.

<Configuration 4>
4. The laser device according to any one of configurations 1 to 3, wherein an adjustment mechanism is provided for changing a width in which the lens folder can move within the movable region.

<Configuration 5>
5. The laser device according to any one of configurations 1 to 4, wherein a gas passage for cooling the lens and the lens folder to which the vibrating body is fixed is provided in the support.

<Configuration 6>
6. The laser device according to claim 1, wherein the support is made of an elastic body that supports the lens folder by elasticity.

<Effect of Configuration 1>
A vibrating body is fixed to the lens folder, and the lens folder is moved so as to vibrate randomly within the movable region. The beam spot of the laser beam can be uniformly amplified with a constant width, and the selection of the amplitude and vibration frequency is easy.
<Effect of Configuration 2>
The beam spot can be randomly vibrated three-dimensionally, and welds with complicated shapes can be welded evenly.
<Effect of Configuration 3>
When a known vibration motor is fixed to the lens folder, only the generated vibration can be transmitted to the lens folder. The lens folder vibrates randomly at high speed within the movable region set by the support base.
<Effect of Configuration 4>
Since the lens folder can move freely within the movable region, the vibration width of the laser spot can be easily increased or decreased by changing the moving width with the adjusting mechanism.
<Effect of Configuration 5>
Radiant heat from the welded portion applied to the lens or the lens holder can be cooled by an inert gas supplied to the welded portion. Cooling efficiency is good because the lens folder vibrates.
<Effect of Configuration 6>
Since the lens folder is supported by elasticity, vibrations and vibration sounds that resonate with the hand of the worker holding the processing head can be reduced.

It is a schematic longitudinal cross-sectional view of the processing head of the laser welding apparatus suitable for implementation of this invention. (A) is MM direction sectional drawing of (b), (b) is NN direction sectional drawing of (a) in the more concrete Example of the support structure of a lens. It is explanatory drawing of the welding operation of a solid object. It is a longitudinal cross-sectional view of the Example which expanded the movable region of the lens folder 28. FIG. It is explanatory drawing of the example which supported the lens folder 28 with the elastic body. It is explanatory drawing of the example which supported the lens folder 28 with the rod-shaped support spring.

  Hereinafter, embodiments of the present invention will be described in detail for each example.

FIG. 1 is a schematic longitudinal sectional view of a processing head of a laser welding apparatus suitable for carrying out the present invention.
The machining head 12 of this embodiment has a bent shape so that the operator can easily support the welding work by hand. As shown in FIG. 1 (a), the machining head 12 includes a light receiving lens 18 that converts a laser beam 16 input from a laser guide 14 into parallel light, a mirror 20 that directs the optical path toward a condenser lens 22, and a laser. And a condenser lens 22 for narrowing the beam 16 to the welding surface of the welding object 26. In the case of a machining head without a bent portion, there is no mirror 20. The diameter of the condensing lens 22 is about 15 mm, for example. The laser beam 16 is narrowed down to, for example, a size of several hundred microns on the welding surface of the welding object 26.

  In the present invention, the beam spot 24 is vibrated randomly by the following mechanism, for example, in the range of 1 mm in width. As shown in FIG. 1B, the condenser lens 22 is integrated with a lens folder 28 made of metal or heat-resistant plastic. A vibration motor 32 is accommodated in the lens folder 28. As the vibration motor 32, a known motor can be used, which has a rotary drive shaft with an eccentric center of gravity and is driven electrically. Any vibration body that vibrates integrally with the lens folder 28 can be used. However, the vibration motor 32 that is frequently used in mobile phones is most suitable because it is small, light, robust, and easy to control.

  Since the vibration motor 32 accommodated in the lens folder 28 is integrated with the lens folder 28, only the generated vibration is transmitted to the lens folder 28. The lens folder 28 is supported by the support 30 inside the processing head 12. The support body 30 supports the lens folder 28 so that it can freely move within a preset movable region.

  In the embodiment of FIG. 1B, the lens folder 28 is supported by a support 30. In this figure, only the left and right portions of the support 30 are shown, and the intermediate portion is not shown. FIG.1 (c) is the longitudinal cross-sectional view. As shown in this figure, a movable region in the XYZ direction is set by the support 30. The adjustment mechanism 35 shown in the figure is realized by, for example, a screw as shown in FIG. This screw is for adjusting the width of the movable region in the X direction. A mechanism that can similarly adjust the width of the movable region in the Y direction or the Z direction can be provided. If the use of the processing head 12 is limited, the adjusting mechanism 35 may be omitted or semi-fixed.

  When the lens folder 28 is vibrated in the movable region in this manner, as shown in FIG. 1B, the beam spot 24 vibrates randomly on the welding surface, and a bead 38 having a set width is formed. Further, since the lens folder 28 can vibrate only within the movable region set by the support 30, the size and position of the beam spot 24 narrowed down by the lens does not fluctuate beyond the limit. Therefore, any part can be welded within a certain range of conditions.

  As shown in FIG. 1A, the condenser lens 22 and the mirror 20 are relatively large components in the apparatus. In the machining head 12 that is supported by the operator's hand, it is necessary to avoid an increase in the size of the drive mechanism for vibrating them. In this embodiment, the vibration motor 32 can be used to sufficiently reduce the size. Moreover, since it can be vibrated at a high frequency of 8000 to 10000 revolutions per sheet, there is an effect that strong and large vibrations that cause a deviation at hand are not generated.

2A and 2B are more specific examples of the lens support structure. FIG. 2A is a cross-sectional view in the MM direction of FIG. 2B, and FIG. 2B is a cross-sectional view in the NN direction of FIG.
As shown in FIGS. 2A and 2B, the lens folder 28 integrated with the condenser lens 22 is supported by the support 30 with a gap corresponding to the movable region. A vibration motor 32 is embedded in the lens folder 28. A power source for driving the vibration motor is on / off controlled by a switch (not shown) attached to an appropriate portion of the machining head.

  When a plane perpendicular to the optical axis 37 of the laser beam is called a reference plane 36, in this embodiment, a movable region is set so that the lens folder 28 can be freely moved by a certain width within the reference plane 36. Yes. Specifically, a gap having a width of W / 2 is provided around the lens folder 28, and the condenser lens 22 can vibrate the beam spot 24 with the maximum width W parallel to the reference plane 36.

  When laser welding is performed, a shielding gas such as nitrogen gas is supplied to the welding surface. This gas is emitted in the direction of the beam spot 24 through the periphery of the support 30. At this time, if the gas flow path 40 is formed in the support 30 as shown in FIG. 2, the shield gas passes through the periphery of the lens folder 28. If a structure with good air permeability is used in this way, the condenser lens 22 and the lens holder 28 can be cooled, so that a robust structure resistant to heat can be realized.

FIG. 3 is an explanatory diagram of a welding operation for a three-dimensional object.
For example, consider a case where two metal plates 50 and 51 are arranged at right angles and welded as shown in FIG. The joint surfaces of both metal plates are bent at a right angle as shown in FIG. 3B, and it is preferable to irradiate the beam spot 24 in the range of length A and width B. In this case, it is not sufficient to vibrate the condenser lens 22 in parallel with the reference plane 36 (FIG. 2). Thus, in addition to the movement of the width W within the reference plane 36, the condenser lens 22 can be moved by the width H in a direction parallel to the optical axis 37 of the laser beam.

FIG. 4 is a longitudinal sectional view of an embodiment in which the movable region of the lens folder 28 is expanded.
In this embodiment, as in the second embodiment, the movable region is set so that the beam spot 24 can be moved by the width W within the reference plane 36 and can be moved by the width H in a direction parallel to the optical axis 37. did. The vibration motor 32 transmits vibration to the lens folder 28, but its moving direction and amplitude are indefinite. Accordingly, the lens folder 28 vibrates freely and randomly in the three-dimensional direction within the set movable region.

  That is, the surface of the object to be welded is not necessarily flat, but has a bent surface and a surface with complicated irregularities. The optimum range to be heated is determined three-dimensionally according to the shape and structure of the welding target region, and the movable range is set. When the vibration is made three-dimensionally, compared with the case where the lens is vibrated two-dimensionally only in the direction of the reference plane perpendicular to the optical axis 37, uniform and high-quality welding becomes possible.

5 and 6 are explanatory views showing modifications of the above support.
FIG. 5 shows an example in which the lens folder 28 is supported by an elastic body. For example, as shown in (a) and (b), if the support spring 42 is used as a support for the lens folder 28, the lens folder 28 can be softly supported. Further, instead of the support spring 42, it may be supported by an elastic body 43 such as rubber or polytetrafluoroethylene resin as shown in FIG.

  FIG. 6 shows an example in which the lens folder 28 is supported by a rod-shaped support spring 44. When supported by several rod-shaped support springs 44, the movable region of the lens folder 28 can be freely set by its elasticity. In the embodiment of FIGS. 5 and 6, since the lens folder 28 is supported by elasticity, vibration sound and vibration that resonates the hand of the worker having the processing head 12 can be reduced.

12 Processing Head 14 Laser Guide 16 Laser Beam 18 Receiving Lens 20 Mirror 22 Condensing Lens 24 Beam Spot 26 Welding Object 28 Lens Folder 30 Supporting Body 32 Vibration Motor 35 Adjustment Mechanism 36 Reference Plane 37 Optical Axis 38 Bead 40 Gas Channel 42 Support spring 43 Elastic body 44 Support spring 50 Metal plate 51 Metal plate

Claims (6)

A condensing lens for narrowing the laser beam to the welding surface;
A lens folder integrated with the condenser lens;
A support base that sets a movable region so that the lens folder can be freely moved by a certain width within a reference plane perpendicular to the optical axis of the laser beam;
A laser device comprising: a vibrating body that is fixed to the lens folder and vibrates and moves the lens folder so as to vibrate randomly within the movable region.   The support body sets a movable region so that the lens folder can be moved by a certain width in a direction parallel to the optical axis of the laser beam in addition to the movement in the reference plane. Item 2. The laser device according to Item 1.   3. The vibration body is a vibration motor having a rotational drive shaft with an eccentric center of gravity, and is fixed to the lens folder so as to transmit only the generated vibration to the lens folder. The laser device described in 1.   4. The laser device according to claim 1, further comprising an adjustment mechanism for changing a width in which the lens folder can move within the movable region.   5. The laser device according to claim 1, wherein a gas passage for cooling the lens and the lens holder to which the vibrating body is fixed is provided in the support.   6. The laser apparatus according to claim 1, wherein the support is made of an elastic body that supports the lens folder by elasticity.

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