Visual guidance laser engraving method and system for pen cap

Abstract

The invention discloses a visual guidance laser marking method and system for a pen cap, and the method comprises the steps: building an image coordinate system and a marking coordinate system in a visual camera and a laser marking machine respectively, and building a mapping relation based on a pen cap clamp marking template; the intersection point of the center line of the pen cap clamp and the end arc serves as a marking reference point, and the center line serves as a marking reference direction; the visual camera takes an image of the pen cap clamp, an image center line and an image imprinting reference point are searched in the image, and the angle offset of the image center line and the coordinate offset of the image imprinting reference point are calculated in an image coordinate system; in combination with the mapping relation, the actual marking datum point and the actual center line direction are obtained in the marking coordinate system, positioning of the pen cap clamp in the marking coordinate system is completed, and marking is conducted through the laser marking machine; therefore, laser marking on the pen cap is achieved under visual guidance, the laser marking device is particularly suitable for marking on pen cap clamps of different sizes, and the marking efficiency and the marking effect of the pen cap are greatly guaranteed.

Description

Technical Field

[0001] This invention relates to the field of injection pen manufacturing equipment technology, and in particular to a visually guided laser engraving method and system for pen caps. Background Technology

[0002] Writing pens, injection pens, and similar items typically include a main pen body for writing or injection, and a pen cap at the tip of the pen body. The pen cap usually has a clip for attaching the pen to a sleeve or pocket.

[0003] To facilitate processing, match pen performance, and enhance visual appeal, pen caps are typically assembled from a cap tube and a cap clip. For example, a pen cap may be assembled from a metal cap tube and a plastic cap clip.

[0004] To match the fully automated assembly line for pen caps, it is planned to set up an engraving station in the assembly line to engrave the pen caps after assembly. In the existing technology, due to the small size of pen caps, engraving on their cap holders is very easy to cause inaccurate engraving positions or even skewness due to errors and deviations caused by clamping, transfer and transportation, resulting in engraving failure. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a reasonably structured visual-guided laser engraving method and system for pen caps, thereby enabling laser engraving on pen caps. This method is particularly suitable for engraving on pen cap clips of different sizes, greatly ensuring the engraving efficiency and effect of pen caps.

[0006] The technical solution adopted in this invention is as follows: A vision-guided laser engraving method for pen caps includes engraving at a preset position on the pen cap clip of a pen cap assembly by a laser engraving machine under the guidance of a vision camera; the engraving method includes the following steps: Establish image coordinate systems and imprint coordinate systems in the vision camera and laser engraving machine respectively, and establish the mapping relationship between the image coordinate systems and the imprint coordinate systems; The intersection of the center line of the pen cap clip and the end arc is taken as the engraving reference point, and the center line is taken as the engraving reference direction. Based on the pen cap clip engraving template, and combined with the mapping relationship between the image coordinate system and the engraving coordinate system, the theoretical coordinate values ​​of the engraving reference point and the theoretical angle of the center line are set in the image coordinate system and the engraving coordinate system, respectively. The vision camera captures an image of the pen cap clip of the pen cap assembly to be engraved; the image center line and the image engraving reference point are found in the image; the angular offset of the image center line from the theoretical angle and the coordinate offset of the image engraving reference point from the theoretical coordinate value are calculated in the image coordinate system. Based on the coordinate offset and angle offset in the image coordinate system, the actual marking reference point and actual center line direction are obtained in the marking coordinate system, and the pen cap clip is positioned in the marking coordinate system, which is then marked by the laser marking machine.

[0007] As a further improvement to the above technical solution: The nine-point calibration principle is used to establish a mapping relationship between the image coordinate system and the engraving coordinate system. This includes: engraving nine circles in the engraving coordinate system of the laser engraving machine with fixed coordinate points as the centers; using a vision camera to find the center image coordinate points of the nine circles in the image coordinate system; and obtaining the mapping relationship between the fixed coordinate points and the image coordinate points.

[0008] In the image coordinate system, obtain the theoretical coordinate values ​​and theoretical angles corresponding to the engraving reference point and center line on the pen cap clamp engraving template. Based on the mapping relationship, obtain the theoretical coordinate values ​​and theoretical angles corresponding to the engraving reference point and center line on the pen cap clamp engraving template in the engraving coordinate system.

[0009] After the visual camera captures an image of the pen cap clip, the arc search algorithm is used to find the end arc in the image, and the straight line search algorithm is used to obtain the straight lines on both sides of the pen cap clip. The center line is calculated from the straight lines on both sides, and the marking reference point is obtained from the intersection of the center line and the arc.

[0010] After obtaining the actual marking reference point and the actual center line direction in the marking coordinate system, the laser marking machine takes the actual marking reference point as the origin point and starts marking from the origin point at a distance of a set length along the center line direction.

[0011] A vision-guided laser engraving system for pen caps, used to perform the engraving method described in any one of the above descriptions.

[0012] As a further improvement to the above technical solution: The laser engraving machine and the vision camera are located in the same engraving station. The assembled pen cap assembly is transported to the engraving station along the conveyor line with the carrier. The output parts of the vision camera and the laser engraving machine are respectively positioned opposite the pen cap clip of the pen cap assembly.

[0013] It also includes a protective cover, which is connected to a dust collection component. The carrier and pen cap assembly that are transported to the engraving station are housed in the protective cover.

[0014] A light source is located in front of the vision camera, the output section of the laser engraving machine, and between the light source and the pen cap assembly. The light source has an arc-shaped structure with an opening facing the pen cap assembly. A through slot is provided on the light source. The vision camera passes through the through slot to capture an image of the pen cap clamp of the pen cap assembly. The laser engraving machine passes through the through slot to engrave an image of the pen cap clamp of the pen cap assembly.

[0015] Compared with the prior art, the present invention has the following beneficial effects: Under visual guidance, this invention combines the selection and setting of the engraving reference point and engraving direction on the pen cap clip, enabling the laser engraving machine to accurately position the current pen cap clip in real time. This achieves accurate and stable laser engraving on the pen cap, effectively reducing or even avoiding the impact of external deviations on the engraving. It is especially suitable for engraving on pen cap clips of different sizes, greatly ensuring the engraving efficiency and effect of the pen cap. The present invention also includes the following advantages: The vision camera captures images in real time, and the center line and engraving reference point of each pen cap clip are located based on the images. The positional deviation of the current pen cap clip is locked and fed back to the laser engraving machine in real time for adaptive adjustment, effectively ensuring the accuracy of the starting point and direction during laser engraving and ensuring the precision of the engraving position. Attached Figure Description

[0016] Figure 1 This is a flowchart of the imprinting method of the present invention.

[0017] Figure 2 This is a schematic diagram of the pen cap assembly of the present invention.

[0018] Figure 3 This is a schematic diagram showing the setting of the center line and engraving reference point on the pen cap clip of the present invention.

[0019] Figure 4 This is a schematic diagram of the 9-point calibration of the present invention.

[0020] Figure 5 This is a schematic diagram of the actual marking position of the laser marking machine of the present invention.

[0021] Figure 6 This is a schematic diagram illustrating the transformation of the length along the actual centerline angle direction for the present invention.

[0022] Figure 7 This is a schematic diagram of the layout of the engraving station on the conveyor line of the present invention.

[0023] Figure 8 This is a schematic diagram of the engraving station of the present invention.

[0024] The components include: 1. Conveyor line; 2. Carrier; 3. Protective cover; 4. Dust collection assembly; 5. Light source; 6. Vision camera; 7. Laser engraving machine; 10. Pen cap assembly; 11. Pen cap clip; 51. Through slot. Detailed Implementation

[0025] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0026] like Figure 1As shown, a vision-guided laser engraving method for pen caps according to this embodiment includes engraving by a laser engraving machine 7 at a preset position of the pen cap clip 11 of the pen cap assembly 10 under the guidance of an image captured by a vision camera 6; the engraving method includes the following steps: Step 1: Establish the coordinate relationship between the vision camera 6 and the laser engraving machine 7; Step 2: The vision camera 6 captures an image of the pen cap clip 11 of the current pen cap assembly 10 and obtains the corresponding image coordinates in real time; Step 3: Based on the coordinate relationship established in Step 1, and combined with the image coordinates acquired in real time by the vision camera 6 in Step 2, the real-time engraving coordinates of the laser engraving machine 7 are obtained, so that the laser engraving machine 7 can perform real-time engraving positioning adjustments for each pen cap assembly 10.

[0027] In the first step, when establishing the coordinate relationship, an image coordinate system and an imprinting coordinate system can be established in the visual camera 6 and the laser engraving machine 7 respectively, and a mapping relationship between the image coordinate system and the imprinting coordinate system can be established; specifically: like Figure 4 As shown, the 9-point calibration principle is used to establish a mapping relationship between the image coordinate system and the imprinting coordinate system; including: imprinting 9 circles with fixed coordinate points as the centers in the imprinting coordinate system of the laser imprinter 7, and using the vision camera 6 to find the center image coordinate points of the 9 circles in the image coordinate system, and obtaining the mapping relationship from the fixed coordinate points and the image coordinate points.

[0028] Of course, in practice, other calibration principles can also be used to establish the mapping relationship between the image coordinate system and the imprint coordinate system, which will not be elaborated here.

[0029] In this embodiment, considering the structural characteristics of the pen cap clip 11, the engraving requirements, and the image acquisition status of the six pairs of pen cap clips 11 by the visual cameras, such as... Figure 2 and Figure 3 As shown, the intersection of the center line and the end arc of the pen cap clip 11 is taken as the engraving reference point, and the center line is taken as the engraving reference direction. Based on the pen cap clip 11 engraving template, and combined with the mapping relationship between the image coordinate system and the engraving coordinate system, the theoretical coordinate values ​​of the engraving reference point and the theoretical angle of the center line are set in the image coordinate system and the engraving coordinate system, respectively.

[0030] In this embodiment, the already engraved and qualified pen cap assembly 10 can be used as the engraving template for the pen cap clip 11. It is clamped within the field of view of the vision camera 6 according to the production operation status. The vision camera 6 captures the image, finds the center line and its intersection with the arc, and sets the intersection coordinates and center line angle in the image coordinate system to obtain the theoretical coordinate values ​​(x1, y1) of the engraving reference point and the theoretical angle r1 of the center line in the image coordinate system. For example, in one embodiment, to simplify coordinate switching, the intersection coordinates can be set as the origin (0, 0), and the direction of the center line can be set as either the X-axis or the Y-axis.

[0031] In this embodiment, the theoretical coordinate values ​​and theoretical angles corresponding to the engraving reference point and center line on the pen cap clip 11 engraving template are obtained in the image coordinate system, and the theoretical coordinate values ​​and theoretical angles corresponding to the engraving reference point and center line on the pen cap clip 11 engraving template in the engraving coordinate system are obtained based on the mapping relationship.

[0032] In this embodiment, based on the theoretical coordinates (x1, y1) of the imprinting reference point and the theoretical angle r1 of the center line in the obtained image coordinate system, the theoretical coordinates (x2, y2) of the imprinting reference point and the theoretical angle r2 of the center line of the pen cap clip 11 imprinting template in the imprinting coordinate system are obtained by combining the mapping relationship between the image coordinate system and the imprinting coordinate system.

[0033] In the second step, the vision camera 6 captures an image of the pen cap assembly 10 and pen cap clip 11 to be engraved; the image center line and the image engraving reference point are found in the image. For example, the angle of the image center line is set to r1', and the coordinates of the image engraving reference point are (x1', y1'); then, in the image coordinate system, the angular offset Δr1 of the image center line from the theoretical angle and the coordinate offset (Δx1', Δy1') of the image engraving reference point from the theoretical coordinate values ​​are calculated.

[0034] In the third step, based on the coordinate offset (Δx1', Δy1') and angle offset Δr1 in the image coordinate system, the actual marking reference point and the actual center line direction are obtained in the marking coordinate system, and the pen cap clip 11 is positioned in the marking coordinate system, and the laser marking machine 7 performs the marking.

[0035] In this embodiment, the actual imprinted reference point coordinates (x2', y2') can be obtained by combining the theoretical coordinates (x2, y2) with the coordinate offset (Δx1', Δy1'), and the actual centerline angle direction r2' can be obtained by combining the theoretical angle r2 with Δr1.

[0036] In one embodiment, the actual marking reference point coordinates obtained in the marking coordinate system of the laser marking machine 7 are x2'=x2+Δx1', y2'=y 2+Δy1', the actual centerline angle direction is r2'=r2+Δr1'.

[0037] In this embodiment, the vision camera 6 captures images in real time, and the center line and engraving reference point of each pen cap clip 11 are located based on the images. The positional deviation of the current pen cap clip 11 is locked and fed back to the laser engraving machine 7 in real time for adaptive adjustment, effectively ensuring the accuracy of the starting point and direction during laser engraving and ensuring the precision of the engraving position.

[0038] With visual guidance, and by selecting and setting the engraving reference point and engraving reference direction on the pen cap clip 11, the laser engraving machine 7 can accurately position the current pen cap clip 11 in real time, achieving accurate and stable laser engraving on the pen cap 10, effectively reducing or even avoiding the impact of external deviations on the engraving.

[0039] In this embodiment, during actual operation, after the vision camera 6 captures an image of the pen cap clip 11, the end arc is found in the image using an arc search algorithm, and the straight lines on both sides of the pen cap clip 11 are obtained using a straight line search algorithm. The center line is calculated from the straight lines on both sides, and then the marking reference point is obtained from the intersection of the center line and the arc.

[0040] In this embodiment, in the image captured by the visual camera 6, such as Figure 3 As shown, the basic shape of the pen cap clip 11 can be clearly identified, such as the straight lines on both sides and the arc at the end. Then, the center line is calculated by averaging the coordinates of the straight lines on both sides. The center line is then extended and combined with the arc at the end to obtain the intersection point.

[0041] After obtaining the actual marking reference point and the actual center line direction in the marking coordinate system, the laser marking machine 7 takes the actual marking reference point as the origin point and starts marking from the origin point at a distance of a set length along the center line direction.

[0042] exist Figure 5 In the embodiment shown, the center line of the pen cap clip 11 is horizontally arranged, and the end arc is located at the right end; after determining the actual engraving reference point ( Figure 5 (Middle of the right end arc) and the actual centerline direction ( Figure 5 After (in the horizontal direction), using the actual engraving reference point as the origin, move it along the actual centerline direction by a set length, for example... Figure 5 Move the center to the left by a set length L, using this as the starting point for engraving, to achieve precise positioning of the engraving.

[0043] In this embodiment, the length L can be determined according to the actual engraving requirements.

[0044] In this embodiment, the precise positioning of the engraving position relative to the pen cap clip 11 is achieved by combining the actual engraving reference point, the actual center line direction, and the set length. In one embodiment, for example... Figure 5 In this case, the engraving can begin by moving a certain distance (e.g., half the engraving width) from the starting point in a direction perpendicular to the actual center line. Figure 5 The "N" is engraved in the middle.

[0045] Of course, after determining the starting point of the engraving, that is, after accurately locating the engraving position on the pen cap clip 11, the corresponding engraving process can be carried out according to the actual situation.

[0046] In this embodiment, during actual operation, after obtaining the actual marking reference point (x2', y2') and the actual centerline angle direction r2' in the marking coordinate system of the laser marking machine 7, as follows: Figure 6 As shown, the set length (e.g., the set length L mentioned above) needs to be converted into a moving coordinate (Δx2, Δy2) along the angular direction r2' in the marking coordinate system. The marking starting point (x0, y0) is then obtained by combining the actual marking reference point (x2', y2') with the moving coordinate (Δx2, Δy2), where x0 = x2' + Δx2 and y0 = y2'. + Δy2.

[0047] The visually guided laser engraving system for pen caps in this embodiment is used to perform any of the engraving methods described above.

[0048] like Figure 7 and Figure 8 As shown, the laser engraving machine 7 and the vision camera 6 are arranged in the same engraving station. The assembled pen cap assembly 10 is transported to the engraving station along the conveyor line 1 with the carrier 2. The output parts of the vision camera 6 and the laser engraving machine 7 are respectively positioned opposite the pen cap clip 11 of the pen cap assembly 10.

[0049] It also includes a protective cover 3, which is connected to a dust collection component 4. The carrier 2 and pen cap assembly 10, which are transported to the engraving station, are housed in the protective cover 3. Dust is removed in a timely manner during engraving to ensure the quality of engraving.

[0050] A light source 5 is located in front of the output section of the vision camera 6 and the laser engraving machine 7, and between it and the pen cap assembly 10. The light source 5 has an arc-shaped structure with an opening facing the pen cap assembly 10. A through slot 51 is provided on the light source 5. The vision camera 6 passes through the through slot 51 to capture an image of the pen cap clip 11 of the pen cap assembly 10. The laser engraving machine 7 passes through the through slot 51 to engrave an image of the pen cap clip 11 of the pen cap assembly 10.

[0051] This invention enables accurate and stable laser engraving on pen caps, effectively reducing or even avoiding the impact of external deviations on the engraving process. It is especially suitable for engraving on pen cap clips of different sizes, greatly ensuring the engraving efficiency and effect of pen caps.

[0052] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0053] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A visually guided laser engraving method for pen caps, characterized in that: The method includes engraving at a preset position on the pen cap clip (11) of the pen cap assembly (10) by a laser engraving machine (7) under the guidance of an image captured by a visual camera (6); the engraving method includes the following steps: In the visual camera (6) and the laser engraving machine (7), establish the image coordinate system and the engraving coordinate system respectively, and establish the mapping relationship between the image coordinate system and the engraving coordinate system; Take the intersection of the center line and the end arc of the pen cap clip (11) as the engraving reference point, and take the center line as the engraving reference direction; based on the pen cap clip (11) engraving template, and combined with the mapping relationship between the image coordinate system and the engraving coordinate system, set the theoretical coordinate value of the engraving reference point and the theoretical angle of the center line in the image coordinate system and the engraving coordinate system respectively. The vision camera (6) captures images of the pen cap assembly (10) and pen cap clip (11) to be engraved; the image center line and the image engraving reference point are found in the image; the angular offset of the image center line from the theoretical angle and the coordinate offset of the image engraving reference point from the theoretical coordinate value are calculated in the image coordinate system. Based on the coordinate offset and angle offset in the image coordinate system, the actual marking reference point and actual center line direction are obtained in the marking coordinate system, and the pen cap clip (11) is positioned in the marking coordinate system and marked by the laser marking machine (7).

2. The visually guided laser engraving method for pen caps as described in claim 1, characterized in that: The 9-point calibration principle is adopted to establish a mapping relationship between the image coordinate system and the imprinting coordinate system. This includes: imprinting 9 circles in the imprinting coordinate system of the laser imprinter (7) with fixed coordinate points as the center, and using the vision camera (6) to find the center image coordinate points of the 9 circles in the image coordinate system, and obtaining the mapping relationship from the fixed coordinate points and the image coordinate points.

3. The visually guided laser engraving method for pen caps as described in claim 1, characterized in that: In the image coordinate system, obtain the theoretical coordinate values ​​and theoretical angles corresponding to the engraving reference point and center line on the pen cap clip (11) engraving template. Based on the mapping relationship, obtain the theoretical coordinate values ​​and theoretical angles corresponding to the engraving reference point and center line on the pen cap clip (11) engraving template in the engraving coordinate system.

4. The visually guided laser engraving method for pen caps as described in claim 1, characterized in that: After the visual camera (6) takes an image of the pen cap clip (11), the arc search algorithm is used to find the end arc in the image, and the straight line search algorithm is used to obtain the straight lines on both sides of the pen cap clip (11). The center line is calculated from the straight lines on both sides, and the imprinting reference point is obtained from the intersection of the center line and the arc.

5. The visually guided laser engraving method for pen caps as described in claim 1, characterized in that: After obtaining the actual marking reference point and the actual center line direction in the marking coordinate system, the laser marking machine (7) takes the actual marking reference point as the origin point and starts marking from the origin point at a distance of a set length along the center line direction.

6. A vision-guided laser engraving system for pen caps, characterized in that: Used to perform the engraving method according to any one of claims 1-5.

7. The vision-guided laser engraving system for pen caps as described in claim 6, characterized in that: The laser engraving machine (7) and the vision camera (6) are located in the same engraving station. The assembled pen cap assembly (10) is transported to the engraving station along the conveyor line (1) with the carrier (2). The output parts of the vision camera (6) and the laser engraving machine (7) are respectively positioned opposite the pen cap clip (11) of the pen cap assembly (10).

8. The vision-guided laser engraving system for pen caps as described in claim 7, characterized in that: It also includes a protective cover (3), which is connected to a dust collection component (4). The carrier (2) and pen cap component (10) that are transported to the engraving station are housed in the protective cover (3).

9. The vision-guided laser engraving system for pen caps as described in claim 7, characterized in that: A light source (5) is provided in front of the output of the vision camera (6) and the laser engraving machine (7) and between it and the pen cap assembly (10). The light source (5) forms an arc-shaped structure with an opening facing the pen cap assembly (10). A through groove (51) is provided on the light source (5). The vision camera (6) passes through the through groove (51) to capture an image of the pen cap assembly (10) and the pen cap clip (11). The laser engraving machine (7) passes through the through groove (51) to engrave the pen cap assembly (10) and the pen cap clip (11).

Images