GB2097148A

GB2097148A - Laser ray apparatus comprising and oscillating mirror

Info

Publication number: GB2097148A
Application number: GB8210816A
Authority: GB
Original assignee: Centro Ricerche Fiat SCpA
Current assignee: Centro Ricerche Fiat SCpA
Priority date: 1981-04-17
Filing date: 1982-04-14
Publication date: 1982-10-27
Also published as: IT8167531A0; SE8202399L; GB2097148B; IT1144173B; SE456973B; DE3213667C2; DE3213667A1; FR2504045B1; FR2504045A1

Abstract

A laser ray apparatus of the type comprising at least a mirror (2) arranged to reflect, towards a predetermined region (4), a laser light beam (3) generated by a respective source, and means (1) arranged to impose onto the mirror (2) an oscillatory motion which determines, for each incident laser light beam (3a), a distribution of the corresponding reflected beam (3b) within a predetermined angular field ( alpha ), within which the said predetermined region (4) is situated. The means (1) comprise: a tipping support (27) to which the mirror (2) is connected; a motor (11); and a motion conversion unit (20) which converts the rotary motion of a shaft (17) of the motor (11) into an oscillatory motion of the tipping support (27). <IMAGE>

Description

SPECIFICATION Improvement in and to a laser ray apparatus The present invention relates to an improvement in and to a laser ray apparatus. More particularly, the present invention relates to a power laser ray apparatusfor the treatment, such as, for example, welding, cutting, surface hardening, etc., of metal materials. It is known that the apparatuses of the type arranged to carry out the said treatments comprise substantially a laser light source, a focusing system and at least a vibrating mirror which reflects the luminous beam emitted by the source towards the zone on which the desired treatment has to be carried out.

The object of the present invention is to provide a laser ray apparatus of the type specified hereinabove and which may carry out thermal treatments on metal materials in a particularly efficient manner.

The present invention relates to a laser ray apparatus of the type comprising at least a mirror arranged to reflect, towards a predetermined region, a laser light beam generated by a respective source, and means arranged to impose to said mirror an oscillatory motion which determines, for each incident laser light beam, a distribution of the corresponding reflected beam within a predetermined angular field inside which the said predetermined region is situated, characterized in that said means comprise: a tipping support to which the said mirror is connected, a motor and a motion conversion unit which converts the rotary motion of a shaft of said motor into an oscillatory motion of said tipping support.

For a better understanding of the present invention a preferred embodiment thereof will now be described, by way of a non limiting example, with reference to the accompanying drawings, in which: Figure 1 is an elevational view of a portion of the apparatus of the present invention, illustrated by an example of application; and Figure 2 is an enlarged sectional view taken along line ll-ll of Figure 1 and with some parts cut away for the sake of clarity.

Referring now in particular to Figure 1, reference numberal 1 indicates generally a support device for supporting a mirror 2 arranged to deviate during the use a laser light beam 3 towards a region 4 defined by the two edges, facing one another, of pieces 5 and 6 which have to be welded to one another along said edges. Said device 1 is part of an apparatus (not shown) which comprises a source (not shown) which emits the high power beam 3, and comprises as well a focusing system (not shown) which focuses the said beam 3 and, conveniently, other reflecting mirrors.

The device 1 is conveniently supported by a vibration-damping bed 8, to which a vertical support plate 10 is fixed by means of bolts 9. This latter supports in a cantilevered fashion a motor 11 by means of a respective connection flange 12, and supports as well, in a central position, a pulley 14 which is coupled, by means of a belt 15, to a corresponding pulley 16 keyed on a shaft 17 of the motor 11. Coupled to the pulley 14 is a motion conversion unit indicated generally by reference numeral 20; this unit is substantially capable of converting a rotary motion of a shaft 21 of the pulley 14 into an axially oscillatory motion with adjustable amplitude of a stem 22 of a connection rod 23. Plate 10 supports also, at an end, a pivot 25, about which rotates and end of bracket 26 whose opposite end is connected to a ring 27.This latter supports, by means of bolts 28, a plate 29, conveniently circular, which is maintained at a certain distance from the ring 27 by means of a plurality of tubular spacers 30.

At the part opposite that which faces the support ring 27, the plate 29 supports the mirror 2; finally, ring 27 has a radial tab 32 which extends towards the outer part of said ring and is coupled, by means of a pivot 33, to a fork member 34 connected to the stem 22 of the connecting rod 23 at the side opposite that which is connected to the said motion conversion unit 20.

With particular reference to Figure 2, it is observed that the shaft 21 of the pulley 14 (not shown in Figure 2) is rotating about a respective axis 35 and is supported by means of bearings 36 relative to a support body 37 conveniently connected in a manner not shown to the plate 10 shown in Figure 1. The bearing 36 is conveniently locked to the body 37 by means of a flange 39 and bolts 40 (only one of which is visible in Figure 2). The shaft 21 has also a portion 42 which extends beyond the flange 39 and has an axis 43 which does not coincide with the axis 35; therefore, the portion 42 of the shaft 21 rotates eccentrically relative to shaft 21. Portion 42, in its turn, supports a tubular eccentric 44 to which the eye 46 of the connecting rod 23 is connected by means of a bearing 45.The tubular eccentric 44 has an axis of symmetry, indicated by reference numeral 48, whose distance from the axis 43 conveniently is equal to the distance between this latter and the axis 35 of the shaft 21. The tubular eccentric 44 and the eccentric portion 42 of the shaft 35 are apt to rotate angularly with respect to one another, and to this end there are provided means which allow both a relative positioning of these elements and a locking, after the positioning has been carried out, of the eccentric 44 relative to the portion 42, in order to allow the eccentric 44 to be made to rotate by the shaft 21. Said means may be even very different from each other.For example, it would be possible to form on the portion 42 a radial toothing and on the eccentric 44 a radial seating disposed at the side facing the said toothing and as large as the cavity comprised between two adjacent teeth of said toothing. A shaped key could then be positioned so as to occupy the space delimited by said seating and cavity, in orderto angularly couple the portion 42 and the eccentric 44, orto allow, when extracted, the rotation of the eccentric 44 relative to the shaft 21.

According to another example, the said means could advantageously be provided by using a unit known on the market as "Harmonic Drive" and substantially formed by a wave generating elliptical element provided with a ball bearing, by a flexible crown gear whose teeth are turned towards the outside and which, when mounted on the elliptical element, assumes its elliptical shape, and by a rigid crown gear having teeth turned towards the interior whose number is slightly higher than that of the teeth of the flexible crown gear. Both crowns have their teeth always engaged at the ends of the main axis of the elliptical element. In this specific case, the elliptical element would be releasably connected to the portion 42, and the crown would be fixed to the element 44.In the adjustment phase the elliptical element would be disengaged from the portion 42, so that an axial rotation of said element would induce a progressive misalignment of the eccentric 44 relative to the portion 42. In the operative phase the elliptical element, the portion 42, the rigid crown gear and the element 44 would conveniently be rigidly connected to each other so as to rotate all of them at the same angular speed.

The bearing 45 is fixed to the tubular eccentric 44 by means of a spacer 49 and a ring nut 50 which is coupled to a corresponding end thread provided on the eccentric 44. The eye 46 of the connecting rod 23, instead, is fixed to the outer race of the bearing 45 by means of a flange 51 and a plurality of bolts 52, only one of which was shown in Figure 2.

The stem 22 of the connecting rod 23 has a first and a second threaded portion 54, 55 whose facing ends are connected to one another by means of a tie rod 56, and by acting onto said tie rod it is possible to adjust the length of the stem 52 of the connecting rod 23.

The operation of the device 1 is as follows.

Referring in particular to Figure 1, when the motor 11 is not activated, the device 1 is stationary in the position shown, so that an incident beam 3a is reflected by the mirror 2 and originates a reflected beam shown by full line 3b. The angulation of the mirror 2 is adjustable by simply acting onto the tie rod 56 which determines a rotation of the ring 27 and, consequently, of the mirror 2, about the pivot 25. This adjustment allows beam 3b to be correctly centered onto region 4 which will have to be submitted to the desired treatment (welding between the pieces 5 and 6).

The feeding of the motor 11 gives rise, through the pulleys 14 and 16 and the belt 15, to the rotation of the shaft 21 about the axis 35 (see Figure 2). This rotation is converted into a substantially axial oscillation of the stem 22 of the connecting rod 23, inasmuch as the eye 46 of the connecting rod 23 follows the combined evolutions of the eccentric 44 and the eccentric portion 42 of the shaft 21. The oscillations of the stem 22 are then transferred, through the tab 32, to the ring 27 which therefore oscillates about the pivot 25 and drags the plate 29 and, consequently, the mirror 2. Accordingly, by varying the inclination of the mirror 2 relative to the incident beam 3a, it is obtained that the reflected beam 3b oscillates within an angle a between two opposite ends at which the beam 3b is indicated by dashed lines.The adjustment of the amplitude of the angle a may be carried out by simply acting on the relative positioning of the eccentric 44 in respect of the eccentric portion 42 of the shaft 21. In fact, it will be possible to act in such a manner as to accentuate to the maximum the total eccentricity relative to the shaft 21, in which case the angle a will have its maximum value, or it will be possible to reduce to a minimum or even eliminate completely the eccentricity by rotating the eccentric 44 in such a manner as to make the respective axis coincide with the axis 35 of the shaft 21. Between these two extreme conditions there are included all the values of the angle a which may be selected everytime for carrying out the desired treatment.

Finally, the adjustment of the speed of vibration of the mirror 2 may conveniently be carried out by adjusting the rotation speed of the shaft 17 of the motor 11 or by suitably changing the pulleys 14 and 16.

From the analysis of the characteristics of the device 1 according to the teachings of the present invention it is clearly apparent that this device allows to overcome the disadvantages of the known devices mentioned hereinabove. In fact, this device allows to carry out all the desired adjustments in a somewhat simple and exact manner, and without anihow involving successive losses of time by the operator.

Finally, it is clear that modifications and variations may be made to the described embodiment of the device 1, without departing from the scope of the present invention.

For example, it is obvious that an apparatus of the type described hereinabove may comprise more than one device 1 disposed, for example, in such a way as to make the reflected beam 3b to assume, as a whole, oscillations in accordance with planes perpendicular to each other.

Claims

1. A laser ray apparatus of the type comprising at least a mirror arranged to reflect, towards a predetermined region, a laser light beam generated by a respective source, and means arranged to impose to said mirror an oscillatory motion which determines, for each incident laser light beam, a distribution of the corresponding reflected beam within a predetermined angular field (a) inside which the said predetermined region is situated, characterized in that the said means comprise: a tipping support to which the said mirror is connected, a motor, and a motion inversion unit which converts the rotary motion of a shaft of the said motor into an oscillatory motion of said tipping support.

2. An apparatus as claimed in Claim 1, characterized in that the said motion conversion unit comprises an adjustable eccentricity system angularly coupled to the said shaft of the said motor and a connecting rod which connects the said system to the said tipping support.

3. An apparatus as claimed in Claim 2, characterized in that the said adjustable eccentricity system comprises an eccentric shaft actuated through the said motor, and a tubular eccentric angularly coupled to the said eccentric shaft and whose angular position relative to the said eccentric shaft is adjustable; the said connecting rod being coupled to the said tubular eccentric.

4. An appartus as claimed in Claim 3, characte rized in that the eccentricities exhibited by said eccentric shaft and by said tubular eccentric are equal.

5. An apparatus as claimed in Claims 3 and 4, characterized in that the said connecting rod has its eye coupled to said tubular eccentric by means of a bearing.

6. An.apparatus as claimed in any of the Claims from 2 to 5, characterized in that the said connecting rod has a stem whose length is adjustable.

7. An apparatus as claimed in Claim 6, characterized in that the said stem has two threaded portions coupled to one another by means of a tie rod which allows the said adjustment of the length.

8. An apparatus as claimed in any of the Claims from 2 to 7, characterized in that the said connecting rod is coupled to the said tipping support by means of an articulation member.

9. An apparatus as claimed in any of the preceding Claims, characterized in comprising adjustment means for adjusting the angular speed of the rotary motion of the said motor.

10. A laser ray apparatus, substantially as described hereinabove with reference to the accompanying drawings.