CN108747049B

CN108747049B - Implementation method of laser cutting machine for positioning plate by using CCD

Info

Publication number: CN108747049B
Application number: CN201810611173.5A
Authority: CN
Inventors: 李正上; 陈明; 黄兴义; 郑五一; 肖俊清; 初兴业
Original assignee: Suzhou Dazu Songgu Intelligent Equipment Co ltd
Current assignee: Suzhou Dazu Songgu Intelligent Equipment Co ltd
Priority date: 2018-06-14
Filing date: 2018-06-14
Publication date: 2020-04-10
Anticipated expiration: 2038-06-14
Also published as: CN108747049A

Abstract

The invention discloses a laser cutting machine for positioning a plate by using a CCD (charge coupled device) and an implementation method thereof, belonging to the technical field of special processing. After the CCD device obtains the placing position and the angle information of the plate through shooting, the position information of the plate relative to the cutting head can be obtained through superposition operation of the result and the offset information which is stored in the CCD device and is relative to the cutting head. And the calculated position information is transmitted to a numerical control system through network communication, and the numerical control system can quickly obtain the zero point information of the plate. On the premise that the highest pixel of the CCD is determined, the shooting identification range is narrowed, the number of pixel points of unit size can be increased, and therefore identification accuracy is improved. Therefore, in the aspects of economy and precision, the range of the CCD device which needs to be subjected to video identification is determined according to the range of the zero offset position of the plate which can be ensured by manual rapid feeding in batch operation.

Description

Implementation method of laser cutting machine for positioning plate by using CCD

Technical Field

The invention belongs to the technical field of special processing, and particularly relates to an implementation method of a laser cutting machine for positioning a plate by using a CCD (charge coupled device).

Background

A planar laser cutting machine performs a pattern cutting work on a rectangular plate material by using a laser. The cutting pattern or the machining path is determined by an NC program file generated in advance using CAM software. The position coordinates of the machining path in the NC program file are determined with respect to the zero point coordinates of the plate material, and the position coordinates of the laser cutting machine are determined with respect to the zero point coordinates of the machine. In practical use, particularly for large or thick plates, if manual feeding is expected to realize that the zero point and the coordinate of each processed plate coincide with those of a machine tool, the time and the labor are wasted. Therefore, on a laser cutting machine, a method is usually adopted to determine the relative position and deflection angle of the zero point of the plate relative to the zero point of the machine and feed the relative position and deflection angle back to a numerical control system, and the numerical control system performs operation processing according to the obtained data to correct the actual motion track into an expected value. Therefore, the unification of the relative position coordinates in the processing program file and the absolute position coordinates of the machine tool is realized.

As shown in fig. 6, which is a principle of positioning a plate of a conventional laser cutting machine, a method commonly used in the laser cutting machine at present is to move a laser cutting head from inside to outside of the plate from a zero point position of the plate close to a machine tool in the plate, and when the laser cutting head passes through an edge of the plate, a signal of a capacitive sensor installed in the cutting head jumps to determine a position coordinate of a certain point on the edge of the plate. The position coordinates of two points on one long side of the rectangle and the point coordinates on one adjacent short side are respectively determined by repeating the principle for 3 times, and the position of a corner formed by the long side and the short side of the rectangle plate (namely the zero point position of the plate) and the deflection angle of the corner can be determined.

Disclosure of Invention

The purpose of the invention is as follows: in order to overcome the above disadvantages, the present invention provides a laser cutting machine using a CCD for positioning a plate, which can solve the problems of automatically identifying a zero point position of the plate and a deflection angle of the plate by using a capacitive sensor, but the following problems need to be improved:

1. the overall recognition time is longer: first using a capacitive sensor to find the sheet boundary requires the cutting head to move slowly close to the sheet surface so that the capacitive sensor has sufficient reaction time to confirm the sheet boundary when the cutting head moves out of the sheet range, and often requires moving back into the sheet range again after first moving out of the sheet range and moving out the secondary confirmation sheet position at a slower speed. In addition, the identification of three points is required in the whole identification process, and the time consumption is basically more than 30 seconds;

2. the recognition accuracy is not high: when the capacitive type edge searching method is used for searching edges, the numerical value received by the capacitive sensor comes from the circular nozzle body at the tail end of the cutting head and the inductive capacitance on the surface of the plate. When the cutting head is moved to a distance outside the edge of the plate, the change value is enough to be detected by the sensor, so that the edge searching precision is basically over 1 mm;

3. interference is easy to receive: accurate feedback of the capacitance value requires that the sheet eventually achieve a reliable connection to the ground through contact with the machine tool. Therefore, the capacitance value between the cutting head and the ground actually reflects the capacitance value between the cutting head and the ground. When the connection between the plate and the ground is not good due to various reasons, the capacitance value is unstable, and the edge searching precision is also influenced.

The processing time of the laser cutting machine, particularly the processing efficiency of a thin plate, is continuously improved, and the edge searching time of 30 seconds in the original capacitance edge searching mode cannot meet the requirement of high-efficiency production. From the perspective of improving the overall efficiency of the laser cutting machine, the edge searching time needs to be shortened. In addition, the processing precision of the traditional capacitor edge searching is gradually improved under the background of improvement of the overall market demand of the laser industry. To meet market demands, recognition accuracy needs to be improved.

The technical scheme is as follows: the implementation method of the laser cutting machine for positioning the plate by using the CCD comprises a laser cutting head and a CCD recognition device, wherein the laser cutting head and the CCD recognition device are respectively arranged on the laser cutting machine, and the CCD recognition device is arranged close to the laser cutting head; the CCD recognition device is provided with an annular light source, a dustproof protection cover and an air cylinder. According to the laser cutting machine for positioning the plate by using the CCD, a CCD identification device (a main device for identifying the plate) is required to be arranged beside a cutting head by using a CCD technology; an annular light source (an auxiliary device for illuminating the identified plate to avoid the problem that the CCD identification device cannot identify the plate when the light is insufficient); a dustproof protective cover and a cylinder (the protective device is opened only during identification to avoid the CCD identification device from being polluted by metal slag or dust in long-term use), and a fixed frame is arranged (the relative position of the CCD identification device on a cutting head on a cutting plane is ensured to be fixed).

The invention also provides an implementation method of the laser cutting machine for positioning the plate by using the CCD, which comprises the following steps:

1) the distance between the central position of the CCD recognition device and the central position of the laser cutting head in the X/Y plane is kept unchanged;

2) the distance between the center position of the CCD recognition device and the nozzle of the laser cutting head in the X direction is Xo, and the distance in the Y direction is Yo;

3) firstly, moving a nozzle of a laser cutting head to the position near a zero point of a plate in a plate range, wherein the whole range does not exceed the identification range of a CCD (charge coupled device) identification device (2);

4) then executing a zero point identification program, automatically moving the CCD identification device to the position above the zero point of the plate by the numerical control system according to the obtained values of Xo and Yo, and shooting and identifying to obtain that the position of the plate relative to the placement position of the CCD identification device in the X-axis direction is Xc and the position in the Y-axis direction is Yc;

5) meanwhile, when the CCD recognition device shoots, the numerical control system records that the actual position of the X axis is Xa and the actual position of the Y axis is Ya;

6) the zero position coordinate Xz of the plate in the X direction and the zero position coordinate Yz of the plate in the Y direction obtained by the numerical control system are respectively as follows:

Xz=Xa+Xc-Xo

Yz=Ya+Yc-Yo；

7) and the numerical control system controls the laser cutting head to move to the zero coordinate position, and the whole zero identification process is completed.

Further, an implementation method of the laser cutting machine for positioning the plate by using the CCD further comprises the following steps: in step 1), the CCD identification device is kept fixed with the deflection angle of the cross beam of the machine tool when being installed, namely the coordinate of the CCD identification device is fixed with the coordinate of the machine tool.

Further, an implementation method of the laser cutting machine for positioning the plate by using the CCD further comprises the following steps:

after the CCD recognition device finishes the zero point shooting of the plate, the CCD recognition device moves a certain distance along the direction of one edge of the plate to capture the position of one point on the edge of the plate, and the deflection angle A of the edge, namely the deflection angle A of the plate, is calculated by combining the zero point recognized by the first shooting.

under the premise that the highest pixel of the CCD identification device is determined, the CCD identification device reduces the shooting identification range and can increase the number of pixels in unit size, so that the identification precision is improved.

The range of the CCD recognition device needing video recognition is determined according to the range of the zero offset position of the plate which can be ensured by manual quick feeding in batch work.

the laser cutting head and the CCD recognition device are arranged above the plate in a hanging mode.

Further, the method for realizing the laser cutting machine by using the CCD to position the plate is characterized in that the edge searching precision of the CCD recognition device is more than or equal to 0.01 mm.

when the plate position is identified, the dustproof protective cover is driven to be opened by the air cylinder, and the CCD identification device works;

when the plate position is identified, the dustproof protection cover for protecting the CCD identification device is restored to a closed state when the plate is machined.

When the plate is processed, the CCD identification device is easily polluted by the generated metal dust. And when the plate position is identified, protecting the dust cover of the CCD identification device to recover the closed state.

when the light is insufficient, the annular light source is turned on to illuminate the plate.

The technical scheme shows that the invention has the following beneficial effects: the laser cutting machine for positioning the plate by using the CCD has the following advantages that:

1. this application has promoted and has sought limit efficiency. In the field of laser cutting machines, with the gradual popularization of high-power lasers, the cutting efficiency of the cutting machine is also continuously improved. In batch processing, the edge searching operation needs to be completed before each plate processing. Therefore, the improvement of the edge searching efficiency is very important for improving the integral cutting efficiency of the laser cutting machine. The new CCD technology is used for searching the edge, so that the edge searching time can be shortened from about 30 seconds of capacitance edge searching to 3-5 seconds, and the preparation time before cutting is greatly shortened.

2. The CCD technology can improve the edge searching precision. In order to maximize the utilization of the sheet, the machine tool user usually has compact cutting patterns arranged on the sheet, or has a secondary edge finding and re-cutting requirement. The millimeter-level edge searching precision of the traditional capacitive sensor cannot meet the precision requirement which is continuously improved at present. The CCD technology is used for edge searching, so that the edge searching precision can be improved to 0.01mm level or even higher.

3. The use of CCD technology can avoid the effects of interference. When the CCD technology is used for searching the edges, the cutting head does not need to be close to the surface of the plate, and only the CCD recognition device and the surface of the plate need to be kept at a fixed distance. The visual imaging is adopted, so that no requirement is imposed on the grounding of the plate.

Drawings

Fig. 1 and 2 are schematic structural views of a laser cutting machine for positioning a plate by using a CCD according to the present invention;

FIG. 3 is a schematic structural diagram of a CCD identification device according to the present invention;

FIG. 4 is a diagram showing the positional relationship between the laser cutting head and the CCD recognition device according to the present invention;

FIG. 5 is a schematic view of the working principle of the laser cutting machine for positioning a plate by using a CCD according to the present invention;

fig. 6 is a schematic diagram illustrating the working principle of the positioning of the existing laser cutting machine according to the present invention.

In the figure: 1 laser cutting head, 2CCD recognition device, 3 annular light source, 4 dustproof safety covers, 5 cylinders.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be considered as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "a plurality" means two or more unless explicitly defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

Examples

The laser cutting machine for positioning the plate material by using the CCD as shown in fig. 1-4 comprises a laser cutting head 1 and a CCD recognition device 2, wherein the laser cutting head 1 and the CCD recognition device 2 are respectively mounted on the laser cutting machine, and the CCD recognition device 2 is located beside the laser cutting head 1; the CCD recognition device 2 is provided with an annular light source 3, a dustproof protection cover 4 and a cylinder 5. Wherein, the edge searching precision of the CCD identification device 2 is more than or equal to 0.01 mm. In order to realize the positioning of the plate by using the CCD technology, the CCD identification device 2 is required to be arranged at a fixed position beside the laser cutting head 1, and when the laser cutting head 1 moves in an X/Y plane, the relative position and the angle between the CCD identification device 2 and the laser cutting head 1 are always unchanged.

Based on the above structure, the implementation method of the laser cutting machine using the CCD for plate positioning as shown in fig. 5 includes the following steps:

1) the distance between the central position of the CCD recognition device 2 and the central position of the laser cutting head 1 in the X/Y plane is kept constant;

2) the distance between the center position of the CCD recognition device 2 and the nozzle of the laser cutting head 1 in the X direction is Xo, and the distance in the Y direction is Yo;

3) firstly, moving a nozzle of a laser cutting head 1 to the position near a zero point of a plate in a plate range, wherein the whole range does not exceed the identification range of a CCD identification device 2;

4) then executing a zero point identification program, automatically moving the CCD identification device 2 to the position above the zero point of the plate by the numerical control system according to the obtained values of Xo and Yo, and shooting and identifying to obtain that the position of the plate relative to the placement position of the CCD identification device 2 in the X-axis direction is Xc and the position in the Y-axis direction is Yc;

5) meanwhile, when the CCD recognition device 2 shoots, the numerical control system records that the actual position of the X axis is Xa and the actual position of the Y axis is Ya;

Xz=Xa+Xc-Xo

Yz=Ya+Yc-Yo；

7) the numerical control system controls the laser cutting head 1 to move to the zero coordinate position, and the whole zero identification process is completed;

in the step 1), the CCD identification device 2 keeps a fixed deflection angle with a cross beam of a machine tool when being installed, namely the coordinate of the CCD identification device 2 is fixed with the coordinate of the machine tool;

after the CCD recognition device 2 finishes the zero point shooting of the plate, the CCD recognition device 2 moves a certain distance along the direction of one edge of the plate to capture the position of one point on the edge of the plate, and the deflection angle of the edge, namely the deflection angle A of the plate, is calculated by combining with the zero point recognized by the first shooting;

on the premise that the highest pixel of the CCD identification device 2 is determined, the CCD identification device 2 reduces the shooting identification range and can increase the number of pixel points of unit size, so that the identification precision is improved;

the range of the CCD recognition device 2 needing video recognition is determined according to the range of the zero offset position of the plate which can be ensured by manual rapid feeding during batch operation;

the laser cutting head 1 and the CCD recognition device 2 are arranged above the plate in a hanging manner;

when the plate position is identified, the dustproof protective cover 4 is driven to be opened by the air cylinder 5, and the CCD identification device 2 works;

when the plate position is identified and the plate is processed, the dustproof protection cover 4 of the CCD identification device 2 is protected to return to a closed state;

when the light is insufficient, the annular light source 3 is turned on to illuminate the plate.

The method for recognizing the zero point position and deflection of the plate through CCD shooting. A method for determining the position of CCD camera by moving the nozzle of cutting head to the vicinity of the zero point of plate and running the recognition program. In accomplishing a whole set of CCD identification device structure of seeking limit function, include: the CCD identification device comprises a CCD identification device body, a special industrial lens, an annular light source and a CCD protection device capable of being opened and closed. The application mainly relates to the application of an image recognition and processing technology in an information processing technology to a traditional processing machine tool; the prior art mainly applies electrical technology to identify changes in capacitance values. The invention is realized by the added CCD identification device 2 with a protection function, and is not dependent on a cutting head manufacturer; the prior art relies on the capacitive sensor built in the cutting head to realize, is limited by the cutting head producer.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that modifications can be made by those skilled in the art without departing from the principle of the present invention, and these modifications should also be construed as the protection scope of the present invention.

Claims

1. A method for realizing a laser cutting machine for positioning a plate by using a CCD (charge coupled device) is characterized by comprising the following steps of: the device comprises a laser cutting head (1) and a CCD recognition device (2), wherein the laser cutting head (1) and the CCD recognition device (2) are respectively arranged on a laser cutting machine, and the CCD recognition device (2) is arranged close to the laser cutting head (1); the CCD recognition device (2) is provided with an annular light source (3), a dustproof protection cover (4) and a cylinder (5);

the implementation method of the laser cutting machine for positioning the plate by using the CCD comprises the following steps:

1) the distance between the central position of the CCD recognition device (2) and the central position of the laser cutting head (1) in the X/Y plane is kept unchanged;

2) the distance between the center position of the CCD recognition device (2) and the nozzle of the laser cutting head (1) in the X direction is Xo, and the distance in the Y direction is Yo;

3) firstly, moving a nozzle of a laser cutting head (1) to the position near a zero point of a plate in a plate range, wherein the whole range does not exceed the identification range of a CCD (charge coupled device) identification device (2);

4) then executing a zero point identification program, automatically moving the CCD identification device (2) to the position above the zero point of the plate by the numerical control system according to the obtained values of Xo and Yo, and shooting and identifying to obtain that the position of the plate relative to the placement position of the CCD identification device (2) in the X-axis direction is Xc and the position in the Y-axis direction is Yc;

5) meanwhile, when the CCD recognition device (2) shoots, the numerical control system records that the actual position of the X axis is Xa and the actual position of the Y axis is Ya;

Xz=Xa+Xc-Xo

Yz=Ya+Yc-Yo；

7) and the numerical control system controls the laser cutting head (1) to move to the zero coordinate position, and the whole zero identification process is completed.

2. The method for implementing a laser cutting machine for positioning a plate by using a CCD as claimed in claim 1, wherein: further comprising the steps of: in the step 1), the CCD identification device (2) keeps a fixed deflection angle with a machine tool beam when being installed, namely, the coordinate of the CCD identification device (2) is fixed with the machine tool coordinate.

3. The method for implementing a laser cutting machine for positioning a plate by using a CCD as claimed in claim 2, wherein: further comprising the steps of: after the CCD recognition device (2) finishes the shooting of the zero point of the plate, the CCD recognition device (2) moves a certain distance along the direction of one edge of the plate to capture the position of one point on the edge of the plate, and the deflection angle A of the edge, namely the deflection angle A of the plate, is calculated by combining the zero point recognized by the first shooting.

4. The method for implementing a laser cutting machine for positioning a plate by using a CCD as claimed in claim 2, wherein: further comprising the steps of: on the premise that the highest pixel of the CCD identification device (2) is determined, the CCD identification device (2) reduces the shooting identification range and can increase the number of pixel points of unit size, so that the identification precision is improved;

the range of the CCD recognition device (2) needing video recognition is determined according to the range of the zero offset position of the plate which can be ensured by manual quick feeding in batch work.

5. The method for implementing a laser cutting machine for positioning a plate by using a CCD as claimed in claim 2, wherein: further comprising the steps of: the laser cutting head (1) and the CCD recognition device (2) are arranged above the plate in a hanging mode.

6. The method for implementing a laser cutting machine for positioning a plate by using a CCD as claimed in claim 1, wherein: the edge searching precision of the CCD recognition device (2) is more than or equal to 0.01 mm.

7. The method for implementing a laser cutting machine for positioning a plate by using a CCD as claimed in claim 2, wherein: further comprising the steps of:

when the plate position is identified, the dustproof protective cover (4) is driven to be opened by the air cylinder (5), and the CCD identification device (2) works;

when the plate position is identified, the dustproof protection cover (4) for protecting the CCD identification device (2) is recovered to be in a closed state when the plate is machined.

8. The method for implementing a laser cutting machine for positioning a plate by using a CCD as claimed in claim 2, wherein: further comprising the steps of:

when the light is insufficient, the annular light source (3) is turned on to illuminate the plate.