CN105855697A - Three-dimensional laser precise curved surface milling method - Google Patents

Abstract

A laser three-dimensional fine curved surface milling method belongs to the field of laser processing, and relates to a highly efficient precise three-dimensional curved surface component milling method. The invention includes a new method for selecting a processing path, a new method for selecting a focus point, and a special processing fixture. The invention performs three-dimensional space positioning on the focus position according to the contour of the curved surface to be processed, and realizes the high-precision laser processing of the curved surface components including spherical components. It can effectively avoid the interference of the laser defocus due to the height change of the processing surface. It does not need to use Z-axis real-time follow-up during the processing process, and can achieve the purpose of surface milling to ensure processing accuracy by strictly restricting the coordinate position of the laser beam along the focused scanning path of the curved surface. . The positioning process is simple, the processing efficiency is high, and the profile of the processed surface has wide applicability.

Description

A method of laser three-dimensional fine surface milling

technical field

The invention relates to a laser three-dimensional fine curved surface milling method, which belongs to the field of laser processing.

Background technique

"National Medium and Long-Term Science and Technology Development Plan (2006-2020)" and National Natural Science Foundation of China "Mechanical Engineering Discipline Development Strategy Report (2011-2020)" both listed complex surface digital manufacturing technology as one of the priority topics in the manufacturing industry one. With the development of major special projects such as "high-end CNC machine tools and basic manufacturing equipment" and "large aircraft", there is an unprecedented urgent demand for efficient and precise manufacturing technology of key complex curved surface parts. Three-dimensional B turbines, compressors, etc., as an important part of aero-engines, are typical curved parts; the important application of high-precision spherical tungsten-cobalt cemented carbide materials is used for oil drilling pump valve balls. In addition, with the rapid development of high-end equipment performance requirements in medical and health, aerospace, electronics, mechanical transportation and other industrial fields, a large number of new material spherical components have emerged as high-performance key components, such as ceramics, hard alloys and other difficult-to-machine Material structure. The femoral head prosthesis used in medicine is obtained by milling spherical alumina ceramics, which is highly valued for its corrosion resistance and wear resistance; ceramic ball bearings are developed from metal bearings, but their high temperature resistance and corrosion resistance make This type of bearing is especially suitable for high-speed and ultra-high-speed working environments, and has broad application prospects and potential huge economic benefits. However, the processing of these spherical components, especially the fine processing, has been facing challenges in manufacturing technology, especially when the processing requirements have been extended from two-dimensional to three-dimensional, and the simple shape and position accuracy requirements have jumped to the precision and performance. Precision machining requirements.

As an advanced manufacturing technology, laser processing has unique advantages such as non-contact processing, large processing freedom, and open processing environment. part. The development of new laser processing methods and the realization of three-dimensional fine machining of spherical component surfaces are of great significance to solve the current bottlenecks in the manufacture of complex curved surfaces, especially hard and brittle materials such as ceramics. When laser processing a curved surface, since the surface of the component is not on the same plane, the defocus phenomenon during processing will greatly interfere with the processing accuracy and quality. However, due to the limitation of Z-axis positioning accuracy, moving speed and monitoring feedback system of the machine tool, in the process of laser processing, the method of using Z-axis follow-up to adjust the defocus amount in real time according to the height change of the processed surface is widely used in practical applications. It is still not feasible, especially for the milling of high-precision curved surfaces with small undulations, it is urgent to develop an effective laser focus position compensation method on the curved surface processing path. According to the requirements of processing accuracy, the coordinates of the laser beam scanning path are strictly restricted. points to ensure the accuracy of processing in the horizontal and vertical directions, which is especially important for the surface processing of small fine curved parts, and there is no report on the use of three-axis laser processing systems for finishing spherical surfaces. , successfully realized the three-axis laser processing system for fine processing of curved surfaces including spherical, and its precision can reach hundreds of microns.

Contents of the invention

In order to solve the above problems, the present invention provides a high-precision laser processing method for curved surface components including spherical components, which can effectively avoid the interference of the laser defocus due to the height change of the processing surface, and does not need to be used in the processing process. The real-time follow-up of the Z-axis can achieve the purpose of surface milling to ensure processing accuracy by strictly restricting the coordinate position of the laser beam along the focused scanning path of the curved surface. The positioning process is simple, the processing efficiency is high, and the contour of the curved surface is widely applicable, and it is characterized in that:

1. According to the processing accuracy, the processing area is divided, and the incident focus position of the laser processing is three-dimensionally positioned from the horizontal space and the vertical space respectively, so as to realize the three-dimensional space coordinate constraint of the focus point position along the processing path of the curved surface to be processed, and the processing process is controlled by the laser Performed for zero defocus on the upper surface of the component. And a new set of fixtures was designed.

2. First divide the surface to be processed parallel to the X-axis in the horizontal space into N (N is the area divided by the processing surface, N ₁ , N ₂ .... N _n from top to bottom) equal parts (such as As shown in Figure 1), the higher the machining accuracy requirement, the larger the value of N. Then contour projection is performed on each area separately, taking

is the focus coordinates of area N ₁ , and so on,

is the focus coordinates of area N ₂ , where x, y are the horizontal and vertical coordinates of the processed surface, along the positive direction of x, respectively (x ₁ ,y ₁ ), (x ₂ ,y ₂ )….(x _m ,y _m ), and n is the coordinate in the Z direction, which are n ₁ , n ₂ ...n _n in sequence along the positive Z direction.

3. Complete the processing of the corresponding areas N ₁ , N ₂ .... N _n in turn according to the determined coordinates of each focal point, and the number of scans is selected according to the focal point , (d is the number of scans required to process the same depth in the planar material, h is the number of focal points), and the total number of scans in the entire N area is still d. Complete the processing of each surface division area in turn, and then complete the surface processing of the entire component. In this way, the first point is focused processing, and the rest is processed with defocusing amount. The defocusing amount is the difference between the height of this point and the first point. By analogy, the second point is used as the precise focus to scan the entire path. The second point is focusing processing, and the rest is processing with defocusing amount. The defocusing amount is the difference between the height of the second focal point. In this way, each point is focused and processed for the same number of times, and at the same time with the same defocusing amount Work the same number of times to ensure that everything is milled to the same depth.

4. Design a special processing device, which includes a vacuum valve (1), a bearing (2), a support seat (3), a claw (4), a cylinder (5), a ratchet (6), a cylinder fixing device (7), Base (8), spring hole (9), groove (11), and spring leaf (12); there is a spring leaf on one side of the support seat, and the spring leaf is connected with the spring ball, and there is a hole on the side of the ratchet that is connected with the spring ball. The matching spring hole has a groove on the long side of the bearing, which is used for fixing the bearing and the support seat; the driving device includes a cylinder, a claw, and the cylinder sends air to the head, and pushes the claw so that the straight side of the ratchet angle is perpendicular to the base. The claw falls back, the cylinder pumps air, the claw returns to its original position, and when the spherical member to be processed is placed on the bearing, the drive mechanism makes the bearing rotate synchronously.

Further, an arc-shaped groove is left on one side of the bearing, and components are placed in the groove for fixing the bearing and the support seat.

The number of ratchet horns is selected according to the machining accuracy, and there is a bead hole on the inner side of each ratchet horn of the ratchet, which is matched with the spring ball of the support seat, and the claw is pushed so that the straight side of the ratchet angle is perpendicular to the base, and the support seat The spring ball enters the spring hole, so that the claws can accurately rotate the corresponding angle each time the ratchet is pushed.

Description of drawings

Figure 1 is a schematic diagram of processing coordinates.

Figure 2 is a diagram of the processing device.

1. Vacuum valve 2, bearing 3, support seat 4, claw 5, cylinder 6, ratchet 7, cylinder fixing device 8, base 9, spring hole 11, groove 12, spring leaf 13, workpiece

Figure 3 The overall shape of the sample

Figure 4 Depth of the arc groove at the highest point

Figure 5 Depth of arc groove at lowest point

detailed description

Mill three equidistant 4*4 rectangular slots in a stainless steel hemisphere with a diameter of 12mm, fix them on the fixture as shown in Figure 2, and divide each rectangular slot into 5 areas. Select four points in area 1 as the focus positions, process each focus 100 times, and scan the entire area 1 for each processing, and complete area 1; complete areas 2, 3, 4, 5. Control the ratchet to rotate 120 degrees, and then complete the second and third grooves in the same way to obtain sample 1#, and measure the depth of the groove, the result is shown in Figure 5.

Claims (2)

1. Laser processing method for fine curved surface, characterized in that: In the horizontal space, the surface to be processed is divided into N parallel to the X-axis direction, N is the area divided by the processing surface, which is N ₁ , N ₂ .... N _n in turn, and then the contour projection is performed on each area respectively, taking is the focus coordinates of area N ₁ , is the focus coordinates of area N ₂ , and so on, where x, y are the horizontal and vertical coordinates of the processed surface, along the positive direction of x, respectively (x ₁ ,y ₁ ), (x ₂ ,y ₂ )….(x _m ,y _m ), n is the coordinate in the Z direction, along the positive Z direction are n ₁ , n ₂ ...n _n in turn; Complete the processing of the corresponding area N ₁ , N ₂ .... N _n in turn according to the determined coordinates of each focal point, and the number of scans is selected according to the focal point where d is the number of scans required to process the same depth in the planar material, h is the number of focal points, and the processing of each curved surface division area is completed in turn, and then the surface processing of the entire component is completed; thus, the first point is Focus processing, the rest is processing with defocus amount, the defocus amount is the difference between the height of this place and the first point, and so on, the second point is used as the precise focus, scanning the entire path, and the second point is focus processing , and the rest are processed with defocusing amount, the defocusing amount is the difference between the height of the second focal point, so that each point is focused and processed the same number of times, and at the same time the same number of times is processed with the same defocusing amount to ensure that each Mill the same depth everywhere. 2. according to the described method of claim 1, it is characterized in that: design special-purpose processing device, this device comprises vacuum valve (1), bearing (2), support seat (3), claw (4), cylinder (5), Ratchet (6), cylinder fixing device (7), base (8), spring hole (9), groove (11), and spring leaf (12); there is a spring leaf on one side of the support seat, and the spring leaf is connected with the spring ball , There is a spring hole matching the spring ball on one side of the ratchet, and a groove is left on the long side of the bearing for fixing the bearing and the support seat; the driving device includes a cylinder, a claw, and the cylinder sends air to the head, pushing The claw makes one side of the straight line of the ratchet wheel perpendicular to the base, the claw falls back, the cylinder pumps air, the claw returns to its original position, and when the spherical member to be processed is placed on the bearing, the drive mechanism makes the bearing rotate synchronously.