CN1362310A - Laser beam rotator for laser processing and its processing method - Google Patents

Abstract

The device for laser processing comprises optical lens, lens cone and its support rotating unit, said optical lens is plane lens, on the holding frame of said lens two supporting shafts with coaxial line are set to form a turning support on which the plane lens can be turned at a certain angle round said supporting shaft. Said invention also provides its working process, and the hole formed on the workpiece by using said device is a straight cylindrical hole.

Description

A beam rotation device for laser processing and its processing method

The invention relates to a device for laser processing and a processing method thereof.

In existing laser processing devices, it is often necessary to rotate the laser beam in order to cut and process holes larger than the diameter of the laser beam. In the prior art, the following methods can make the laser beam rotate: CN85204571 discloses a device for laser heat treatment, which uses a rotating light guide mechanism to make the plane mirror rotate with the incident laser beam optical axis as the axis , so as to achieve the function of reflecting the laser beam to draw a circle on the surface of the workpiece; adjusting the angle between the plane mirror and the incident light can change the radius of the drawn circle. The advantage of this method is that it is relatively simple to implement, and the laser energy loss is small; but because the reflected beam has an included angle with the surface of the workpiece, the inner surface of the hole formed by processing is a conical surface, that is to say, the hole punched is not a straight hole , but a tapered hole, which cannot meet the requirements of use in many occasions. If a wedge-shaped prism is used instead of a plane reflector to rotate with the optical axis of the incident laser beam as the axis, the function of making the transmitted laser beam draw a circle on the surface of the workpiece can also be realized, but it also has the defect of a tapered hole. In US4822974, a method of using a rotating combined prism is provided, that is, two opposite prism slopes are placed in parallel on a device that can rotate with the optical axis of the incident laser beam as the axis, so that the transmitted laser beam can draw a circle on the surface of the workpiece. Function. In this method, the laser beam is shot perpendicular to the surface of the workpiece, so the holes are straight cylindrical holes. The disadvantage is that the laser beam passes through the interface of the two lenses, and the energy loss is relatively large.

The object of the present invention is to provide a beam rotation device and a processing method thereof which use a plane mirror to enable the transmitted laser beam to punch straight cylindrical holes on the workpiece.

The object of the present invention is achieved by the following means.

The beam rotating device for laser processing of the present invention includes an optical mirror, a lens barrel and a supporting rotating device thereof, and is characterized in that the optical mirror is a plane lens, and two coaxial wires are arranged on the clamping frame of the mirror. The two support shafts are respectively set in the coaxial holes on the wall of the rotating lens barrel to form a slewing bearing that the plane lens can rotate around the support shaft at a certain angle; The rotating rod used for adjusting the angle, the other end of the rod extends outside the wall of the lens barrel, and the outer circular surface of the rod is provided with a screw thread matched with the internal thread of the circular lens barrel wall hole.

The method of using the above-mentioned beam rotation device for laser processing includes placing the laser and its focusing system near the workpiece to be processed, the beam rotation device is placed on the focused laser light path, and the lens barrel is the same as the focused laser beam. axis, it is characterized in that, the subsequent work process is, according to the radius r of the processing hole, adjust the rotating rod of the beam rotation device, so that the angle θ between the axis of the laser beam and the normal line of the incident surface of the plane lens satisfies the following formula: $\frac{r}{\mathrm{D.}}=\sin \mathrm{\θ}-\frac{1}{2}\frac{\sin 2\mathrm{\θ}}{\sqrt{{\mathrm{no}}^2-{\sin }^2\mathrm{\θ}}}$ or $\mathrm{\θ}=-\mathrm{ArcSin}\left[\frac{1}{a}(b+\frac{c}{{(e+6\sqrt{3}\sqrt{f})}^{1/3}}-{(e+6\sqrt{3}\sqrt{f})}^{1/3})\right]$ Where: a=6Dr, b=-D ² +D ² n ² -r ² , c=(-12D ² n ² r ² -b ² )e=D ⁶ -3D ⁶ n ² +3D ⁶ n ⁴ -D ⁶ n ⁶ +3D ⁴ r ² +12D ⁴ n ² r ² -15D ⁴ n ⁴ r ² +3D ² r ⁴ -39D ² n ² r ⁴ +r ⁶ f＝-D ⁸ n ² r ⁴ +2D ⁸ n ⁴ r ⁴ -D ⁸ n ⁶ r ⁴ -3D ⁶ n ² r ⁶ -14D ⁶ n ⁴ r ⁶ +D ⁶ n ⁶ r ⁶ -3D ⁴ n ² r ⁸ +11D ⁴ n ⁴ r ⁸ -D ² n ² r ¹⁰

In the formula, n is the refractive index of the plane lens to the laser wavelength used, D is the thickness of the plane lens, and r is the radius of the circular hole to be processed.

When using the beam rotation device of the present invention to carry out laser processing on workpieces, holes with different diameters can be processed conveniently by adjusting the setting angle of the plane lens. Since the laser beam passes through the plane lens and directly hits the surface of the workpiece, as long as the axis of the laser beam is not perpendicular to the incident plane of the plane lens, the axis of the outgoing beam will shift, but its direction remains unchanged, resulting in it being on the workpiece The hole formed by the upper processing is the straight cylindrical surface. The angle of inclination of the plane lens is different, and the processed aperture is different. It is very convenient to use. On the other hand, since the laser beam only passes through one plane lens, compared with the combined prism used in the prior art, it has the advantage of less loss of laser energy.

The light beam rotating device and the processing method thereof of the present invention can be conveniently used for processing the microscopic holes of devices such as the surfaces of turbofans of aircraft turbine engines.

Further description will be made below through embodiments and accompanying drawings.

Fig. 1 is a structural schematic diagram of an embodiment of the beam rotation device of the present invention.

Fig. 2 is a schematic diagram of the processing state of the beam rotation device of the present invention.

Referring to Fig. 1, (1) is a circular lens barrel, which is supported on the base (2) by rolling bearings (3). Motor (6) is placed on this base, belt pulley (5) is installed on the motor spindle, and there is a groove at the position corresponding to belt pulley on the outer wall surface of circular lens barrel, and belt (4) is placed wherein. After the motor is started, the circular lens barrel is driven to rotate at the required speed through belt transmission. (8) is a plane lens, and a support frame is provided around the mirror, and a horizontal support shaft (9) is fixedly connected to the support frames at both sides respectively, and they are sleeved on the coaxial shaft on the wall surface of the rotating lens barrel. In the line hole, the plane lens can rotate around the support shaft at a certain angle. (7) is the extension spring that is arranged between the lens barrel wall and the bottom of the lens support frame, and it is used for assisting the supporting lens. (10) is the rotating bar that is used to adjust the angle that is in contact with the plane lens holding frame, and the other end of this bar stretches outside lens barrel wall, so that regulate. The outer circular surface of the rod is provided with a screw thread matched with the inner thread of the wall hole of the circular lens barrel, and the angle of the plane lens can be adjusted when the rod is rotated by hand. In actual use, a collar connection can also be used at the contact between the rotating rod and the clamping frame to ensure that the two are not separated. At this time, the extension spring of the auxiliary support can be omitted.

Referring to Fig. 2, (11) is a laser, the horizontal laser beam that is emitted from the laser is incident on the plane lens (8) in the lens barrel through the focusing system (13), and the laser beam (12) is coaxial with the lens barrel. Angle θ is the angle between the axis of the laser beam and the normal of the plane lens, and D is the thickness of the plane lens. The laser beam axis (14) emitted from the plane lens is parallel to the original laser beam axis (12), but translated by a distance r. When the motor drives the circular lens barrel equipped with the flat lens to rotate, the laser beam emitted from the flat lens will rotate around the axis of the lens barrel, and the radius of rotation is r, and the laser beam will be cut and formed on the left side surface of the workpiece (15). A circular hole of radius r.

In Fig. 2, L1 represents the distance between the laser beam waist and the center of the focusing lens, L2 represents the distance between the center of the focusing lens and the surface of the workpiece, and L3 represents the distance between the center of the plane lens and the surface of the workpiece. In actual use, L1, L2 and L3 should meet the following conditions respectively: L1 should satisfy the paraxial light condition of the lens when the laser beam reaches the focusing lens, L2 should be approximately equal to the focal length of the focusing lens, and L3 should be greater than the backsplash during laser processing In order to prevent the contamination of the plane lens, the spraying distance of the workpiece residue should be 10cm<L3<L2 under normal circumstances.

In practical application, according to the thickness of the plane lens used, its refractive index, and the radius of different cylindrical holes, the calculation formula can be used to calculate the data of the angle θ between the axis of the laser beam and the normal line of the plane lens, and it is made Detailed tables or graphs are available for operators to refer to.

Processing examples are given below.

Select the 266nm wavelength laser output by Nd:YAG laser 4 times frequency, the focusing lens is a convex lens with a focal length of 15cm, set L ₁ to 1m, L ₂ to 15cm, L ₃ to 10cm, and use quartz with a refractive index n of 1.5 The thickness D of the plane lens is 2 mm. When the incident angle θ is adjusted to 30°, the radius r of the straight cylindrical hole punched on the workpiece is 388 μm.

Claims (3)

1. beam rotator that is used for Laser Processing, include the device of optical frames, lens barrel and supporting rotation thereof, it is characterized in that, described optical frames is a planar lens, on the holding frame of this mirror, be provided with the bolster of two coaxial lines, this two bolster is set in the coaxial line hole on the revolving mirror tube wall surface, constitutes the pivoting support that planar lens can turn an angle around this bolster; Also be connected with a dwang that is used for adjusting angle on the holding frame of planar lens, the other end of this bar is stretched outside the lens barrel wall, is provided with the screw thread that matches with circular lens barrel cinclides internal thread on the periphery of this bar.

2. the beam rotator that is used for Laser Processing as claimed in claim 1 is characterized in that, the periphery of described dwang is provided with the screw thread that matches with circular lens barrel cinclides internal thread.

3. the method for using the described beam rotator of claim 1 to carry out Laser Processing, comprise used laser instrument and focusing system thereof are placed on to be processed nearby, described beam rotator places on the laser optical path after the focusing, lens barrel and focusing back laser beam coaxial line, it is characterized in that the course of work after this is, as required the radius r of machining hole, regulate the dwang of beam rotator, make the angle theta between laser beam axis and the planar lens plane of incidence normal satisfy following formula: $\frac{r}{D}=\sin \mathrm{\&theta;}-\frac{1}{2}\frac{\sin 2\mathrm{\&theta;}}{\sqrt{n^2-{\sin }^2\mathrm{\&theta;}}}$ N is the refractive index of planar lens to used optical maser wavelength in the formula, and D is a planar lens thickness, and r is the radius that needs the circular hole of processing.

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