I have recently created a portfolio of my work on YouTube (link to channel). These are promotional sales videos for my employer Ventek’s products which I shot and edited. I did not design or program all the equipment shown, so here is a guide to the videos and my involvement. Ventek has not endorsed or approved these comments or videos, they are entirely my of creation and I am responsible for any errors or omissions.
The Ventek NV4g scanner is their 4th generation veneer clipping system. It is based on the same software and hardware platform as the GSc2000 veneer grader. The previous NV2000 scanner used 3 single board computers programmed in assembly language to provide similar functions but was limited to simple threshold grayscale scanning and could not detect as many types of wood defects or grade the veneer.
- The first part of this video shows the veneer lathe and buffer conveyor that feed veneer ribbons to the NV4g scanner. This area is not provided or controlled by Ventek. This mill uses a close coupled lathe and scanner while most other mills peel the veneer ribbon onto a layer of trays that are later unloaded into the scanner.
- The middle and last sections of the video show the new NV4g scanner, HMI PLC and veneer clipping knife. I designed and wrote the NV4g software. It runs on Microsoft Windows 7 connected to 2 embedded SBCs (single-board-computers which I also programmed) for real-time I/O response which Windows can’t do by itself. The HMI and PLC was programmed by fellow Ventek employee John Koza. The clipping knife controls were provided by Elite Automation.
- The veneer clipping knife is a Raute Wood product but is controlled by a PLC provided by Elite Automation. This unit operates the knife and rolls using hydraulic power while newer designs use electric servo motors which use less power and are more accurate. Knife control is the most critical part of the operation. The knife must be accurately fired about 40 milliseconds before it cuts the wood. The NV4g real-time SBCs must track the wood ribbon using an encoder wheel, constantly measure the speed and fire the blade at the right time to cut at the correct position.
- An older Ventek NV2000 scanner (green tubular tower with light) was still in place between the NV4g scanner and clipping knife. During this field trip it was being disconnected from the other control systems so it could be removed.
- The area after the clipping knife shows Ventek’s new multi-point diverter system. The first diverter after the knife drops trash wood to a conveyor to a wood chipper. The second and third diverters feed trays to supply fish-tail (half sheets) and strip to the pull chain. PLC controls for this area were provided by Elite Automation.
- Full size veneer sheets travel to a higher level and into a stacker. The stacker controls were provided by Elite Automation.
I wish to thank ATCO Wood Products for allowing me to document their production line and also for providing the beta site needed to develop the new system.
You can see a little larger overview of plywood processing in this video provided by USNR which covers other areas of production such as the lathe, ribbon trays, stacker and dryer. If you watch closely, you will see both Ventek GSc2000 and NV2000 scanners in the video.
WARNING: reduce your volume, loud mill noise is present.
This video was shot using my cell phone (Nokia C7) and is not of the highest quality. Apple’s Final Cut Pro stabilized the video enough to make it viewable.
This is one of the second generation systems Ventek provided. Third generation systems are even more compact and use a single conveyor with robots on both sides. I created all the vision software for these parts of the system:
- Two independent lines are used to patch 8 and 10 foot veneer sheets.
- Two Ventek GSc2000 scanners find defects on the veneer sheets and determine where the patches must be placed. I designed and programmed the GSc2000 scanner.
- The patch solutions are passed from the GSc2000 PC to a Robot Control Database PC which stores the patch positions in a database and feeds them to the robots as needed. I designed the database PC and the protocols used to pass information between it, the PLC conveyor controller and the robots.
- A Ventek supplied material handling system moves the sheets along a conveyor where the robots can pick them up and process them. Ventek supplied the PLC controls to operate this system.
- Ventek supplied RefCam reference cameras near each robot to stop the sheet and measure the proper offset and angle to allow the robot to pick the sheet and process it. I designed and programmed the RefCam system.
- Willamette Valley Company provided the Fanuc robots and programmed them to my specifications.
- I designed and programmed all the vector calculations necessary to properly center wood patches on defects and also to reference the sheet at the robot station to allow accurate picking of the sheet and placement of the patches at the station. Sheets can slip or rotate slightly during conveyor transfers and the RefCam system allows them to be re-referenced at the station for processing.
WARNING: reduce your volume, loud mill noise is present.
I was hired by Ventek in 1998 to develop the GS2000, a grayscale scanner that could grade veneer sheets and output a signal allowing a stacker to separate them into packages for later production steps. The GSc2000 was an upgrade to introduce full color scanning which provides better defect detection. I wrote the software necessary for this product and also advised other hardware and mechanical engineers on the selection of other components related to the vision system.
I was always unhappy with how we tracked the veneer sheets during scanning. There were two modes of scanning that I developed for the first products: (1) measure conveyor speed and adjust the camera scan rate to match it and (2) scan the camera at a fixed rate and measure the conveyor speed to allow scaling the image height to produce the correct pixel height. Both methods worked well, but had drawbacks such as not working correctly when the conveyor speed had variations or stopped in the middle of a sheet.
For this product modification I came up with an extra real-time embedded single-board-computer to read the encoder directly and synchronize this reading with camera scanning. This allowed me to know how far each scanned image moved and exactly where it was on the conveyor. The final image could be scaled properly and exact defect positions determined. I named this SBC the CamSync processor and it was later used to provide similar functions for the NV4g project (above).
A veneer composer is a machine that clips veneer strips into good wood and glues them together to produce a continuous ribbon that can then be cut into new sheets of higher grade wood. The whole idea of this process is to take poor quality wood from the roundup area of veneer ribbons (the area peeled by the lathe near the bark before the full width wood) and reprocess it by clipping out the bad areas and then put it back together into something useful. Low grade full sheets can also be cut up into higher grade wood to create high grade sheets, but this is somewhat wasteful of the lower grade areas that are discarded.
What you will see in this video is:
- The manual feeding of strips into the system.
- A wheel system to straighten them for presentation to the scanner and composer knife.
- A split conveyor to remove gaps and provide better flow of material.
- The composer knife and diverter gate.
- The output and cutting of composed sheets.
- The stacking of the finished sheets.
The infeed mechanical systems and GSc2000 scanner was provided by Ventek. The conveyor and composer PLC controls were provided by Elite Automation.