Cognex machine vision chosen by major European sub-contractor

Citation

(2004), "Cognex machine vision chosen by major European sub-contractor", Assembly Automation, Vol. 24 No. 1. https://doi.org/10.1108/aa.2004.03324aaf.001

Cognex machine vision chosen by major European sub-contractor

Cognex machine vision chosen by major European sub-contractor

Keywords: Machine vision, Cognex

Cognex, the world's leading supplier of machine vision systems, announced that Dinalot SA, a sub-contractor for the motor industry, has integrated Cognex's In-Sight 1000 vision systems into a high speed fuel injection production line (Plate 1).

Dinalot SA, a Spanish company, constructs small metallic machine parts for the motor industry. The parts to be inspected are machined metal disks featuring six tapped and countersunk holes. Dinalot manufactures five different versions of these parts.

Plate 1 The two Cognex In-Sight sensors mounted on a robot arm are used to inspect position and diameter of the holes as well as threading

The checks made by the Cognex machine vision system include measuring the diameter of the holes and also their position with respect to each other and relative to a central positioning notch. All these checks were previously carried out manually by an operator and because of the high degree of precision required, the measurements used to take a long time. The checking itself, which involved selective sampling, had the disadvantage of letting through many non-compliant parts.

After studying the production conditions, Ikusmen Vision Artificial, a Cognex integrator partner, put in place a solution that was capable of carrying out the necessary measurements and checks on all manufactured parts whilst at the same time satisfying the key precision, production speed and cost requirements.

The solution

The system comprises two Cognex In-Sight 1000 vision sensors, an XY Cartesian robot and a rack-mounted industrial PC. The PC is used to control the vision sensors and the robot, and to display the current vision inspection image and the measurement results. It is also used at the application tuning stage to configure the two sensors and to indicate which version of the product is to be checked.

Assembly

The In-Sight sensors are mounted on a robot arm as shown in Figure 1. The first In-Sight sensor, mounted vertically above the parts to be inspected, is used to check the position and diameter of the holes. The second In-Sight sensor, mounted at a specific angle, looks inside the holes to check the threading. The horizontal control surface is fitted with LED backlighting manufactured by Cognex.

Figure 1

Control process

The parts arrive at the inspection station after passing through a cleaning bath. The robot picks up the part to be inspected and places it on the control surface. The first In-Sight sensor initially locates the central notch on the part and then calculates its position. Next, the robot moves the camera so that it is above the nominal position of each hole. The vision sensor then calculates the angle of each hole relative to the central notch and measures their diameters. All these measurements are carried out to a level of precision of ±0.02 mm for the diameters and ±0.1° for the angles.

The second In-Sight sensor is then positioned by the robot so that it can inspect the inside of each hole and measure the number of threads and the width of the grooves, thereby checking the quality of the threading. Once these checks are complete, the robot places good parts on a stacking device and the failed parts in a discard container.

Advantages

The entire operation takes only 9s, which means that every part produced by Dinalot can be inspected even for all five different production models. It also ensures that no faulty parts will ever find their way to the end customer. Owing to the Ikusmen solution, it has also been possible to automate the “palletisation” of the manufactured parts. The vision system data obtained during the control process have also allowed Dinalot to refine its machining process.

For more information about machine vision, contact: Leigh Simpson, Cognex UK Ltd, Sunningdale House, 43 Caldecotte Lake Drive, Caldecotte, Milton Keynes, Buckinghamshire, MK7 8LF. Tel: +44 (0) 1908 206033; Fax: +44 (0) 1908 392463; E-mail: lsimpson@cognex.com; Web site: www.cognex.com