RU2795680C1 - Device for detecting veneer defects after peeling - Google Patents

Abstract

FIELD: detecting defects.

SUBSTANCE: invention relates to a device for detecting veneer defects after peeling, which is designed for early detection of defects and timely notification of the operator of the peeling line.

EFFECT: improvement of quality of identifying hard-to-detect defects in veneer lumber after peeling (“rough (coarse) peeling”, “risk” and “obstruction”), on the basis of which the final assessment of lumber quality is made.

2 cl, 5 dwg

Description

Technical field

The invention relates to a device for detecting veneer defects after peeling, which is designed for early detection of defects and timely notification of the operator of the peeling line. The device detects and analyzes defects in the form of “risks”, “blockages”, “non-smooth (rough) peeling” in real time, which enables operators to take timely measures to eliminate the production of low-quality products. Thus, the defect detection device is a tool for intermediate control of the produced veneer, allowing you to achieve high quality, reduce production costs and waste on defects. The use of this device makes it possible to analyze the quality of products much faster, reducing time resources for data processing. Flexible data analysis allows you to significantly increase the efficiency (increasing quality and reducing the cost of raw materials for rejects) of the production line.

Technical problem

The interline interval is the thin sheets of wood made by various methods. For example, it is made by peeling, sawing or planing. For the manufacture of veneer, peeling machines, plywood sawing machines or veneer cutting machines are used. The most common veneer is peeled veneer. It is made from such tree species as oak, pine, birch, alder. During the peeling process, various difficult-to-detect defects can occur on lumber veneer, for example, “non-smooth (rough) peeling”, “risk” and “blockage”. These defects are difficult to detect, because, unlike relatively easily detected defects (“knot”, “veinlet”, “crack”, “hole”, “tar pocket”, “rot”, “blue”, “burrow”, “false kernel") require great attention from the operator. The technical problem is the creation of a device for detecting the above difficult-to-detect defects in veneer lumber after peeling.

State of the art

A known method for determining the quality of lumber, including illumination of the wood surface with optical radiation, scanning of scattered radiation and determination of the size of defects in lumber (RU 2007117461, published 20.11.2008). This analogue does not allow detecting the presence of wood defects that are difficult for “machine vision”, such as rot, blue stain, mold and wormholes.

A device and method for detecting defects in wood are known (WO 9524636, published 09/14/1995). The disadvantage of the known invention is that with its help it is possible to detect only large, pronounced defects in wood, while small defects cannot be detected.

The technical result of the claimed invention is to improve the quality of determining hard-to-detect defects in veneer lumber after peeling, on the basis of which the final assessment of lumber quality is made, while expanding the range of detectable lumber defects.

The essence of the invention

The technical result is achieved due to the fact that the device for detecting veneer defects after peeling, containing: a moving belt with veneer, a frame on which are installed: cameras for obtaining images of the veneer surface and light sources for forming illumination zones and determining visible veneer defects, according to the claimed invention, contains a directional light source located on the frame, from the end of the tape with veneer, perpendicular to the motion vector of the tape, made with the possibility of forming the 1st veneer illumination zone, designed to determine the defect: "rough (rough) peeling" and contains a linear source of scattered light, located on the frame, on top of the tape with veneer, at an angle of 90 degrees to the direction vector of the tape, configured to form the 2nd veneer illumination zone, designed to identify the following defects: “risk”, “blockage”.

In one embodiment of the device for recognizing defects in veneer after peeling, the directional light source consists of two, located opposite each other, light sources located on the frame, at opposite ends of the veneer strip, while the entire surface of the veneer passing through the illumination zone is in luminous flux of said directional light sources.

In another embodiment, a pronounced light-shadow zone is formed on the surface of the veneer, while the defects “non-smooth (rough) peeling”, “risk”, “blockage” have a clear, visually distinguishable appearance.

The hardware-functional part of the device for detecting veneer defects after peeling includes the following elements:

- Video cameras (3) designed to obtain images of the veneer.

- Control unit (10) designed to receive and process images from video cameras to the display and transmit control signals to an external control system;

- Frame (7) with light sources designed to form illumination zones.

The control unit (10) includes the following functional parts:

- Controller (11) designed for arithmetic and logical processing of input signals from video cameras and interface unit (9) and their further processing or transmission to the display, to an external control system, as well as storage of the control program, operational data and variables;

- Interface block (9) designed to connect the displacement sensor (8) to the controller (11);

- Ethernet interface (12), which is used to transfer data over twisted shielded pair to the process control system;

- Displacement sensor (8), which is used to determine the coordinates of the veneer at each particular moment in time.

Brief description of the drawings

FIG.1 - the figure shows a General view of the frame, which is installed: cameras for obtaining images of the surface of the veneer and light sources.

FIG.2 is a schematic representation of the veneer passing through the backlight zone and being in the light flux of directional light sources.

FIG. 3 - image of the surface of the veneer with the defect "non-smooth (rough) peeling" without the presence of the 1st illumination zone and in its presence.

FIG. 4 - image of the veneer surface with a "risk" defect without the presence of the 2nd illumination zone and in its presence.

FIG. 5 is a hardware-functional block diagram of the device.

Positions in the drawings

1. Directional light source.

2. Linear scattered light source.

3. Video cameras for veneer imaging.

4. The direction of the luminous flux of the directional light source.

5. Light sources.

6. Veneer.

7. Frame with light sources.

8. Movement sensor.

9. Pairing block.

10. Control unit.

11. Controller.

12. Ethernet interface.

13. Display.

Implementation of the invention

The invention can be carried out as follows. The tape with veneer (6) passes through the area under the frame (7), above which video cameras (3) and light sources (5) are installed. On top of the frame, perpendicular to the tape movement vector (at an angle of 90 degrees to the veneer tape movement direction vector), there is a linear light source (2). On the side of the frame (7), at the ends of the tape, perpendicular to the motion vector of the tape, there are directional light sources (7). In this case, the surface of the veneer (6) is in the light flux. The light sources (7) are arranged in series: first comes the directional light source (7), then the linear light source zone (2). The directional light source (7) may consist of two light sources located opposite each other. Due to such organization of illumination, a pronounced light-shadow zone is formed on the surface of the veneer, while the defects “Non-smooth peeling”, “Risk”, “Clogging” have a clear, visually distinguishable appearance (Fig. 3, 4). In the zone of vertical illumination, risks become visible, partially blockage. In the zone of horizontal illumination, uneven peeling and blockage become visible. The arrangement order of the 1st and 2nd zones of illumination of the veneer surface can be arbitrary. Matrix video cameras (3) are located above the light sources. Due to the high speed of filming a video camera, three pictures of the same area of the veneer surface are taken for further analysis. The received frames are processed by a pretrained neural network. When a veneer defect is found, the neural network classifies it and marks it as a defect. Defects are classified by a neural network. When training the model, defects are “showed” and they are given a name. The displacement sensor (8) captures the coordinates of the veneer at each moment of time. This data is also transmitted to the control unit (10) via the interface unit (9). The controller (11) combines the data from the video cameras (3) and the displacement sensor (8), giving the operator a visual display of the veneer on the conveyor belt with the selection of defect zones in real time (figure 3, 4), and also saves all information on server. This enables operators to take action to eliminate production in a timely manner. All equipment in the device is mass-produced and can be replaced with a similar one. Machine vision video camera - Basler 60 fps, directional light source - spotlight 5000K, linear light source - lamp 5000K.

EXAMPLES OF CARRYING OUT THE INVENTION

Peeling defects are characterized by a deviation in the flatness of the geometry of an individual section of the veneer. Moreover, the risk defect can be less than 0.2 mm. Visually, this defect is indistinguishable or hardly distinguishable by the eye. When creating special lighting conditions (a directional light source perpendicular to the veneer motion vector), they allow you to visually identify defects due to an artificially created light-shadow zone.

Example 1

Determination of the defect "Non-smooth (rough) peeling" when using the claimed device.

In FIG. Fig. 3 visually shows veneer with a “non-smooth (rough) peeling” defect without the presence of the 1st veneer illumination zone and in its presence (formed by a directional light source).

Example 2

Determination of the "Risk" defect when using the claimed device.

In FIG. 4 visually shows the veneer with the “Risk” defect without the presence of the 2nd veneer illumination zone and with it (formed by a linear source of scattered light).

As can be seen from Examples 1, 2, the presence of 2 veneer illumination zones greatly facilitates the early detection of lumber defects and timely notification of the peeling line operator. During the development of the implementation of the device, experiments were carried out using traditional devices for determining changes in the surface of the material (triangulation), illumination with powerful light sources. With the arrangement of light sources in the final form, implemented in the claimed device, in the illumination zone, defects become visually distinguishable, have clear boundaries and can be classified by the eye even without the use of video cameras, which was not possible without illumination.

Thus, when using the device according to the claimed invention, the quality of determination of hard-to-detect defects in veneer lumber after peeling is improved.

Claims (2)

1. A device for recognizing veneer defects after peeling, containing: a moving belt with veneer, a frame on which are installed: cameras for obtaining images of the veneer surface and light sources for forming illumination zones and determining visible veneer defects, characterized in that it contains a directional light source , located on the frame, from the end of the tape with veneer, perpendicular to the tape motion vector, made with the possibility of forming the 1st veneer illumination zone, designed to determine the defect: “rough peeling”, and contains a linear source of scattered light located on the frame, on top of the tape with veneer, at an angle of 90 degrees to the direction vector of the tape, made with the possibility of forming the 2nd veneer illumination zone, designed to determine the following defects: "risk", "blockage". 2. A device for recognizing veneer defects after peeling according to claim 1, characterized in that the directional light source consists of two light sources located opposite each other, located on the frame, at opposite ends of the veneer tape, while the entire surface of the veneer passing through the backlight zone is located in the luminous flux of the mentioned directional light sources.

Images