Visual precise positioning and depth measuring precise laser engraving machine

Abstract

The utility model discloses a visual precise positioning and depth measuring precise laser engraving machine, which is characterized in that an arranged camera shoots a contour image of a workpiece fixed on an XY-axis moving platform through a reflecting film and feeds back the contour image to a computer, and the computer transmits the contour image of the workpiece to a display in real time to drive the XY-axis moving platform to display the contour image of the workpiece. The contour of the workpiece is subjected to edge searching and positioning through the cross reference of the display, and the origin of coordinates of the XY-axis moving platform is determined. By driving the XY moving platform, the engraved part of the workpiece can be located at the position required by a drawing, the machining and positioning precision of the workpiece is greatly improved, and repeated positioning is facilitated; the laser displacement sensor located on the sliding rail can detect the engraving depth and transmit the engraving depth to a computer under the condition that a workpiece is not disassembled and clamped repeatedly, and the engraving depth is controllable. And the diameter of the light spot output by the original smaller laser is enlarged by 1-8 times through the variable-multiple beam expander, so that precise engraving is realized.

Description

Technical Field

[0001] The utility model relates to a laser engraving device, in particular to a precision laser engraving machine with visual precise positioning and depth measurement. Background Technique

[0002] Engraving is one of the processes in component processing. Existing engraving devices include machining centers, electric discharge machines, and laser marking machines, etc., each having different advantages and disadvantages.

[0003] The machining center realizes engraving by installing a suitable tool (drill bit) on the spindle of the machining center and programming, so that the device performs cutting processing according to the set program path; the electric discharge machine first needs to process a copper or stone grinding electrode, and through the discharge of the electrode, the surface of the object to be processed is etched with the same pattern as the electrode. Both the machining center and the electric discharge machine have the advantages of high primary positioning accuracy and controllable machining depth, etc., but they both have the disadvantages of high cost, long part clamping time, inability to machine acute angles, and the line width of the engraved text being limited by the tool, etc.

[0004] A laser marking machine is also called a "laser coding machine" or a "laser marking printer". It is a device that uses a high-energy laser beam to engrave the required characters, graphics, and images on the surface of an object. Its structure is provided with a laser, and in the optical path of the laser, an isolator, a galvanometer scanner, and a field lens are successively arranged. The laser and the galvanometer scanner are connected to a computer, and a display is also connected to the computer. A workpiece fixing table is arranged below the field lens. During operation, the workpiece (the object to be processed) needs to be placed on the fixing table. The computer controls the laser to emit a laser beam, which passes through the isolator to the optical scanning head of the galvanometer scanner. The optical scanning head (laser beam) is controlled by the computer to deflect in the X-Y plane. Finally, through focusing, the field lens forms a uniformly sized focused light spot of the laser beam within the entire marking plane, locally irradiates the workpiece, and evaporates the surface layer material of the workpiece to expose the deeper layer material, thereby marking a permanent mark.

[0005] "Precision engraving" refers to engraving precise characters or patterns on alloy steel, with strict requirements for the size, depth, position, line thickness, etc. of the characters or patterns. However, the current positioning method for engraving workpieces using the above-mentioned laser marking machine in the engraving industry is to first clamp the workpiece with a fixture or directly place the workpiece (the object to be processed) on the workbench by hand, rely on visual observation or hold a magnifying glass to find the preview position of the red light emitted by the laser, and then gently tap and move the object to be engraved by hand or other objects to perform edge finding and positioning before laser etching can be carried out. During the processing, it is also necessary to remove the workpiece (or together with the fixture) from the fixed table, and use visual observation or a height gauge probe to measure the depth. If the engraving depth is not reached, repositioning (repeated positioning) and engraving are required, and this process is repeated multiple times until the engraving depth is achieved. However, there is a physical limit to the grinding of the sharp part of the height gauge probe. When the strokes of small characters or patterns are too thin, the height gauge probe cannot enter and the measurement can only be abandoned. The existing method is not only cumbersome and inefficient in operation, but the key is that it cannot ensure the positioning accuracy and the depth measurement of small characters or patterns, resulting in poor consistency of the engraving position of the product, serious quality problems such as double images and double-layer contours, and a high rejection rate, directly affecting the product quality and economic benefits. Therefore, in precision engraving, accurate positioning and depth measurement are the primary technical problems that need to be solved by those skilled in the art. Summary of the Invention

[0006] The utility model is to solve the above-mentioned technical problems existing in the prior art, and provides a precision laser engraving machine with visual accurate positioning and depth measurement.

[0007] The technical solution of the utility model is: a precision laser engraving machine with visual accurate positioning and depth measurement, which is provided with a laser. In the laser optical path of the laser, an isolator, a galvanometer scanner and a field lens are sequentially arranged. The laser and the galvanometer scanner are connected to a computer, and a display is also connected to the computer. A workpiece fixing table is arranged below the field lens. A variable magnification beam expander is fixed between the isolator and the galvanometer scanner; the workpiece fixing table is an XY-axis moving platform, and grating scales are fixed on both the X-axis and the Y-axis of the XY-axis moving platform. The reading output of the grating scale is connected to a coordinate display instrument; the light outlet of the field lens is connected to a transition cavity, and a reflecting film at an angle of 45 degrees with the axis of the light outlet of the field lens is fixed in the transition cavity. The reflecting film transmits laser and refracts visible light, and a camera is arranged in the refraction optical path of the reflecting film; an X-axis slide rail or a Y-axis slide rail is fixed above the workpiece fixing table, and a laser displacement sensor is connected to the X-axis slide rail or the Y-axis slide rail. The emitted light of the laser displacement sensor is vertically downward and the optical axis does not coincide with the laser optical axis of the laser; the camera and the laser displacement sensor are connected to the computer.

[0008] The preferred technical solution is that the variable magnification beam expander is fixed inside the housing. An adjustment window is opened on the housing. A left flange and a right flange are respectively arranged at both ends of the housing. The left flange is connected to the left fixing member. The outlet of the isolator is fixed on the left fixing member. The right flange is connected to the right fixing member. The galvanometer is fixed on the right fixing member. A first through hole is provided on the left fixing member, and a second through hole is provided on the right fixing member. The first through hole, the left flange, the housing, the right flange, the second through hole and the galvanometer are coaxial.

[0009] The above-mentioned visible and precise positioning precision laser engraving machine operates according to the following steps:

[0010] Step 1. Fix the workpiece on the XY-axis moving platform through a fixture.

[0011] Step 2. The camera takes an image of the workpiece contour and transmits it to the display through a computer. Drive the XY-axis moving platform. Through the cross reference on the display, edge finding and positioning of the workpiece contour are carried out. The position of the XY-axis moving platform determined is the origin of the XY-axis coordinates of the coordinate display instrument. Adjust the XY-axis coordinate display of the coordinate display instrument to zero.

[0012] Step 3. Drive the XY-axis moving platform. According to the position requirements for engraving, make the engraved part of the workpiece be located below the transition cavity.

[0013] Step 4. Turn on the laser for engraving. After reaching the set time, pause the laser.

[0014] Step 5. Zero the coordinate display instrument or record the current reading. Drive the XY-axis moving platform to move a length L along the Y-axis or X-axis. Drive the laser displacement sensor to move along the X-axis slide rail or Y-axis slide rail so that the laser displacement sensor is located directly above the engraved workpiece for distance detection. Transmit the detected distance signal to the computer to obtain the engraving depth.

[0015] Step 6. If the engraving depth reaches the design requirements, the engraving ends; otherwise, drive the XY moving platform to move reversely a length L along the Y-axis or X-axis, and return to Step 4.

[0016] The camera provided by the present utility model can capture the contour image of the workpiece fixed on the XY-axis moving platform through a reflective film and feedback it to the computer. The computer transmits the workpiece contour image to the display in real time, drives the XY-axis moving platform, and performs edge finding and positioning on the workpiece contour through the cross reference of the display to determine the coordinate origin of the XY-axis moving platform. By driving the XY moving platform, the carved part of the workpiece can be located at the position required by the drawing, greatly improving the machining and positioning accuracy of the workpiece and facilitating repeated positioning. The laser displacement sensor provided on the slide rail can detect the carving depth and transmit it to the computer without repeated disassembly and clamping of the workpiece, realizing controllable carving depth. The variable magnification beam expander enlarges the output spot diameter of the original small laser by 1-8 times, so that the laser spot falling on the workpiece is reduced to a theoretical diameter of 0.0086 mm through the focusing of the field lens, realizing precision carving. The experimental results show that the carved patterns (circles, squares) can reach 0.09*0.09 mm, letters 0.3*0.3 mm, characters 0.5*0.5 mm, the vertical gap between characters is 0.01 mm, the carving depth can reach more than 0.3 mm, the workpiece positioning accuracy is ±0.001 mm, the repeated positioning accuracy is ±0.002 mm, and the positional tolerance can reach within ±0.02 mm, which is applicable to the precision carving of various molds and parts. The structure of the present utility model is reasonably designed and has the advantages of simple structure, low cost, convenient operation, accurate positioning, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of an embodiment of the present utility model.

[0018] Figure 2 is Figure 1 the A-A view of

[0019] Figure 3 is a schematic circuit diagram of an embodiment of the present utility model.

[0020] Figure 4 is a schematic structural diagram of the left flange, housing and right flange used in an embodiment of the present utility model.

[0021] Figure 5 is a schematic diagram of the left fixing member used in an embodiment of the present utility model.

[0022] Figure 6 is a schematic diagram of the right fixing member used in an embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS Embodiment 1

[0023] A precision laser engraving machine with visual precise positioning and depth measurement according to the present utility model is as Figures 1-6As shown in the figure, similar to the existing laser marking machine, it is equipped with a laser 1 with a wavelength of 1064 nm. The laser 1 selects a Q-switched pulsed laser. In the optical path of the laser 1, an isolator 2, a galvanometer 3, and a field lens 4 are successively arranged. The laser 1 and the galvanometer 3 are connected to a computer 5, and a display 6 is also connected to the computer 5. A workpiece fixing table 7 is arranged below the field lens 4. Different from the existing laser marking machine, a variable magnification beam expander 8 is fixed between the isolator 2 and the galvanometer 3. By adjusting the variable magnification beam expander 8, the output spot diameter of the laser can be enlarged by 1 - 8 times, so that the laser spot falling on the workpiece can be reduced to a theoretical diameter of 0.0086 mm through the focusing of the field lens to achieve precise engraving. The workpiece fixing table 7 is an XY-axis moving platform, which can be manually driven or motor-driven. Grating scales 9 are fixed on both the X-axis and Y-axis of the XY-axis moving platform. The reading output of the grating scales 9 is connected to a coordinate display 10. The light output port of the field lens 4 is connected to a transition cavity 11. A reflective film 11-1 that forms a 45-degree angle with the axis of the light output port of the field lens 4 is fixed inside the transition cavity 11. The reflective film 11-1 is coated with quartz to enable the refraction of visible light and the passage of 1064 nm invisible light. A camera 12 is arranged in the refraction optical path of the reflective film 11-1. An X-axis slide rail 13 is fixed above the workpiece fixing table 7 and can be fixed on the outside of the transition cavity 11. A laser displacement sensor 14 is connected to the X-axis slide rail 13. The laser displacement sensor 14 can be slidably connected to the X-axis slide rail 13 or fixedly connected to the X-axis slide rail 13. In short, it should be ensured that the laser displacement sensor 14 moves relative to the workpiece fixing table 7. The emitted light of the laser displacement sensor 14 is vertically downward (the angle with the vertical line is less than or equal to 3 degrees) and the optical axis does not coincide with the laser optical axis of the laser 1 to avoid mutual interference. The camera 12 and the laser displacement sensor 14 are connected to the computer 5. To ensure the shooting effect of the camera 12, a light-emitting diode 18 that irradiates the workpiece fixing table 7 can be arranged below the transition cavity 11. The laser displacement sensor 14 emits visible red semiconductor laser. According to actual needs, a spot with a diameter of about Φ0.075 mm can be selected, which can replace the probe of the traditional physical altimeter to make precise distance measurement for fine text or pattern strokes.

[0024] The best technical solution is to fix the variable magnification beam expander 8 inside the housing 15. An adjustment window 15-1 is provided on the housing 15 to enable adjustment of the variable magnification beam expander 8. Left and right flanges 15-2 and 15-3 are respectively provided at both ends of the housing 15. The left flange 15-2 is connected to the left fixing member 16, the outlet of the isolator 2 is fixed on the left fixing member 16, the right flange 15-3 is connected to the right fixing member 17, and the galvanometer scanner 3 is fixed on the right fixing member 17. A first through hole 16-1 is provided on the left fixing member 16, and a second through hole 17-1 is provided on the right fixing member 17. The first through hole 16-1, the left flange 15-2, the housing 15, the right flange 15-3, the second through hole 17-1 and the galvanometer scanner 3 are coaxial.

[0025] The operation process is as follows:

[0026] Step 1. Fix the workpiece on the XY-axis moving platform through a fixture.

[0027] Step 2. The camera captures the contour image of the workpiece and transmits it to the display through the computer. Drive the XY-axis moving platform, and perform edge finding and positioning on the workpiece contour through the cross reference on the display. The position of the XY-axis moving platform thus determined is the origin of the XY-axis coordinates of the coordinate display instrument, and adjust the XY-axis coordinate display of the coordinate display instrument to zero.

[0028] Step 3. Drive the XY-axis moving platform to place the carved part of the workpiece below the transition cavity according to the requirements of the drawing.

[0029] Step 4. Turn on the laser for engraving, and pause the laser after reaching the set time.

[0030] Step 5. Zero the coordinate display instrument or record the current reading; drive the XY-axis moving platform to move a length L along the Y-axis or X-axis, drive the laser displacement sensor to move along the X-axis slide rail or Y-axis slide rail, so that the laser displacement sensor is located directly above the carved workpiece for distance detection, and transmit the detected distance signal to the computer to obtain the engraving depth.

[0031] Step 6. If the engraving depth reaches the design requirements, the engraving ends; otherwise, drive the XY moving platform to move back a length L along the Y-axis or X-axis in the reverse direction, that is, return to the zero point of the coordinate display instrument or the recorded reading position, and return to Step 4.

[0032] The accuracy of the grating scale 9 in the embodiment of the present utility model can be calibrated through a reference block (gage block), and a compensation value is set to minimize the error generated by the movement, so as to eliminate the repeated positioning error generated by moving the XY-axis moving platform when measuring the engraving depth.

[0033] The experimental results of the embodiments of the present utility model show that: the engraved patterns (circular, square) can reach 0.09*0.09 mm, the letters can reach 0.3*0.3 mm, the text can reach 0.5*0.5 mm, the vertical gap between the texts is 0.01 mm, the engraving depth can reach more than 0.3 mm, the positional tolerance can reach within ±0.02 mm, the workpiece positioning accuracy is ±0.001 mm, and the repeat positioning accuracy is ±0.002 mm.

Claims

1. A precision laser engraving machine capable of visual accurate positioning and depth measurement, comprising a laser (1), an isolator (2), a galvanometer (3) and a field lens (4) arranged in sequence in the laser light path of the laser (1), the laser (1) and the galvanometer (3) being connected to a computer (5), which is also connected to a display (6), a workpiece fixing table (7) being arranged below the field lens (4), and characterized in that: A variable-magnification beam expander (8) is fixed between the isolator (2) and the galvanometer (3); the workpiece fixing table (7) is an XY-axis movable platform, and a grating ruler (9) is fixed on the X-axis and Y-axis of the XY-axis movable platform, and the reading output of the grating ruler (9) is connected to the coordinate display device (10); the light outlet of the field mirror (4) is connected to the transition cavity (11), and a reflection film (11-1) is fixed in the transition cavity (11) at an angle of 45 degrees to the axis of the light outlet of the field mirror (4), and the reflection film ( 11-1) refracts visible light through laser, and a camera (12) is provided in the refracted light path of the reflective film (11-1); an X-axis slide rail or a Y-axis slide rail (13) is fixed above the workpiece fixing table (7), and a laser displacement sensor (14) is connected to the X-axis slide rail or the Y-axis slide rail (13); the emitted light of the laser displacement sensor (14) is vertically downward and the optical axis does not coincide with the laser optical axis of the laser (1); the camera (12) and the laser displacement sensor (14) are connected to the computer (5).

2. The precision laser engraving machine with visual accurate positioning and depth measurement according to claim 1, characterized in that: The variable-power beam expander (8) is fixed in a shell (15), an adjustment window (15-1) is provided on the shell (15), a left flange (15-2) and a right flange (15-3) are respectively provided at two ends of the shell (15), the left flange (15-2) is connected to a left fixing member (16), an outlet of the isolator (2) is fixed to the left fixing member (16), the right flange (15-3) is connected to a right fixing member (17), the galvanometer (3) is fixed to the right fixing member (17), a first through hole (16-1) is provided on the left fixing member (16), and a second through hole (17-1) is provided on the right fixing member (17), and the first through hole (16-1), the left flange (15-2), the shell (15), the right flange (15-3), the second through hole (17-1) and the galvanometer (3) are coaxial.

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