RU2193956C2 - Apparatus for laser welding - Google Patents

Abstract

FIELD: machine engineering, namely apparatuses for laser welding of thin conductors, possibly in electronics, instrument making and machine engineering. SUBSTANCE: in first variant of invention apparatus includes laser and mounted in optical duct of housing: mirror bihedral prismatic divider with rectangular base, reflector and focusing lens. Cone reflector has inlet opening with diameter equal to that of laser beam. Focusing lens is arranged in optical duct of housing. Rectangular base of prismatic divider has length A=Dl.b, where Dl.b. is diameter of laser beam. In second variant of invention prismatic divider is trihedral and it has base in the form of equilateral triangle with side equal approximately to 0.31 Dl.b. Such design of apparatus allows to perform precision welding of thin conductors or shapes simultaneously at both sides at reducing deformation of welded article due to symmetrical arrangement of welding spots. EFFECT: possibility for precision welding of thin conductors. 2 cl, 2 dwg

Description

 The invention relates to metallurgy and can be used in electronics, instrument and mechanical engineering.

 A device for heating by a laser beam [1].

 The known device comprises a laser, a laser beam splitter, including a translucent reflector and a mirror, as well as two lenses for separate focusing of radiation.

 The main disadvantage of the known device is that the design of the device is quite complicated and at the same time it does not provide for a symmetrical beam separation to form two beams of the same intensity, which does not allow for high-quality double-sided welding of thin conductors to massive products.

 A device for processing an object with a laser beam with an uneven distribution of energy, adopted as a prototype [2].

 The known device comprises a laser and an optical system for beam separation and focusing, consisting of a prismatic divider, deflecting mirrors and a focusing assembly.

 The main disadvantage of the known device lies in the fact that the optical system is a complicated structurally designed mechanism that requires highly qualified staff, which greatly complicates the process during welding of thin conductors. In addition, the use of the known device leads to deformation of the welded products and thinning when welding thin conductors.

 The aim of the invention is to simplify the design of the device for the precision welding of thin conductors or profiles simultaneously from two sides or from three sides (in the case of welding the free end from the end to a flat surface) while reducing the deformation of the welded products due to the symmetrical arrangement of the welded points relative to the longitudinal axis of the conductor (profile).

This technical result is achieved in that a device for laser welding of thin conductors containing a laser and a mirrored dihedral prismatic divider with a rectangular base and a reflector installed in the optical channel of the housing is equipped with a focusing lens located in the optical channel of the housing, the reflector is made conical with an opening at the entrance to with a diameter equal to the diameter of the laser beam, the rectangular base of the prismatic divider has a base length A = D _L.L. where D _L.L is the diameter of the laser beam.

To achieve the claimed technical result when welding conductors on three sides (in the case of welding the free end of the conductor), a device for laser welding of thin conductors containing a laser and a mirror prismatic divider and reflector installed in the optical channel of the housing is equipped with a focusing lens located in the optical channel of the housing, the reflector is made conical with an inlet opening with a diameter equal to the diameter of the laser beam, and the prismatic divider is made trihedral with a base in the form of an equal side triangle with side A ≈ 0.31 • D _L.L , where D _L.L is the diameter of the laser beam.

 Figure 1 shows a diagram of the device, and figure 2 (a-b) is a diagram of the location of the welded points in welding with a dihedral (a) and trihedral (b) prismatic divider.

The device contains a laser emitter 1, generating a laser beam, the diameter of which in the optical channel is equal to D _L.L. The housing 2 of the device is made with an optical channel coaxial with the axis of the laser beam. In the optical channel of the body 2 are arranged mirror prism splitter 3, a conical reflector 4 with an opening at the inlet to the reflector _PTV D = D _LL and the focusing lens 5. The angles of inclination of the prismatic reflective surfaces of the reflector 3 and divider 4 with respect to the vertical axis are equal to 45 ^o .

 The device operates as follows.

 On the coordinate table (not shown) place the product 7 with a conductor (or profile) 6 fixed on it and install it in the focal plane of the lens 5 so that the longitudinal axis of the conductor 6 coincides with the longitudinal plane of symmetry of the prismatic divider 3.

When the laser unit is turned on, a laser beam with a diameter of _{L. L. A is} sent to a device in which it is converted into four beams 8, 9, 10, 11. In this case, the central, most intense part of the laser beam that fell on the prismatic divider 3 is divided into two equal parts 9 and 11, which deviate to the surface of the reflector 4 and, reflected from it, are sent to the lens 5. The peripheral part (rays 8, 10), less intense, is sent directly from the laser emitter 1 to the focusing lens 5. The pairs of rays 8, 9 and 10, 11 are focused separately by lens 5 on the surface of the conductor 6 and on the surface of the massive product 7. The conductor 6 is heated by the peripheral part of the laser beam (rays 8, 10), and the massive product 7 is heated by the central part (rays 9, 11). This ensures a balanced heating of the welded products.

 The rays in pairs 8, 9 and 10, 11 do not overlap, which avoids interference phenomena, and propagate in such a way that after focusing with lens 5 in the focal plane, two pairs of separate welded points are formed, but in each pair the points are in contact with each other, which conditions are provided for the formation of a common melt pool and for obtaining a high-quality welded joint.

As a result, the surface of the product 7 and the conductor 6 are heated and melted on both sides with the formation of two weld points (figure 2, a)
The main structural parameters of the device are obtained as follows. Hole size D _{of holes} entering the reflector 4 taken equal to the diameter D of the laser beam _LL. Reducing the size of the aperture D _{of holes} entering the reflector causes aperturing the laser beam, and inefficient use of its power, while increasing the size D _{of holes} formed by four welding points not in contact with each other, which is unacceptable for the given welding circuit, t. To affords low-quality welded joint.

It was experimentally established that for given parameters of the laser beam (radiation energy, pulse duration, focal length) for welding conductors (or profiles) with a diameter of ~ 50 to ~ 300 μm, the width of the base of the prismatic divider overlapping the laser beam should be B = ( 0.4-0.6) - D _L.L.

 Changing the value of B outside the specified range leads to the formation of low-quality welded joints. On the one hand, due to insufficient heating of the conductor, and on the other hand, due to its overheating and substantial thinning.

The length of the base A of the prismatic divider 3 is equal to the diameter D _{L. L of the} laser beam at the entrance to the device, because with a decrease in size A, the efficiency of using the laser beam decreases and overheating and thinning of the conductor in the longitudinal direction are also possible.

 When welding the free end of the conductor from the end side, the optimal welding scheme is three points (Fig.2, b). In this case, the device is equipped with a trihedral prismatic divider, which divides the laser beam into three equal parts, focused by the lens on the end and side surfaces of the conductor.

 Using the proposed device for laser welding of thin conductors (or profiles) with a diameter from - 50 to ~ 300 μm with a massive product allows to avoid thinning of conductors (or profile) and deformations when welding along the length of the conductor and the most effective device when welding dissimilar materials. In particular, such combinations: conductor - brass, bronze, gold, silver plated and tinned copper, massive product - stainless steel, nickel alloys, contact pads based on silver-containing paste on the surface of non-metals (quartz, ceramics).

Thus, the design of the device was greatly simplified, and its use allowed to improve the quality of the welded joint and reduce the deformation of the welded conductors with a massive product
Sources of information:
1 Application (Japan) 62-179887, publ. 0708.1987, 61-22771, 23 K 26/00.

 2. US Patent 4,315,130, publ. 02.09.1982, volume 1015, 2, MKI B 23 K 27/00, HKI 219-121L.

Claims (2)

1. A device for laser welding of thin conductors, comprising a laser and a mirrored dihedral prismatic divider with a rectangular base and a reflector installed in the optical channel of the housing, characterized in that it is equipped with a focusing lens located in the optical channel of the housing, the reflector is made conical with a hole at the entrance with a diameter equal to the diameter of the laser beam, the rectangular base of the prismatic divider has a base length A = D _L.L , where D _L.L is the diameter of the laser beam. 2. A device for laser welding of thin conductors, containing a laser and a mirror prismatic divider and reflector installed in the optical channel of the housing, characterized in that it is equipped with a focusing lens placed in the optical channel of the housing, the reflector is made conical with an opening at the entrance with a diameter equal to the diameter of the laser beam, and the prismatic divider is made trihedral with the base in the form of an equilateral triangle with a side ≈ 0.31 D _L.L , where D _L.L is the diameter of the laser beam.

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