Application of machine vision in the medical device industry

1 Introduction

With the continuous improvement and update of medical level and medical equipment, disposable injection needles are deeply loved by users for their convenience and hygiene, and their demand is increasing rapidly. The appearance of the needle directly affects the quality of disposable injection needles. Therefore, in order to reduce the number of defective products, it is necessary to increase the inspection process. Manual appearance inspection and product marking are expensive and unreliable. At the same time, it means inhumane and monotonous work. Here, the automated machine vision system provides a solution to these problems.

2 Disadvantages of disposable injection needles

A disposable injection needle can be divided into two parts: the needle seat and the needle. The defect of the needle seat can be ignored in terms of product quality. However, there are two defects in the needle: first, burrs may be generated at the needle tip during the manufacturing process; second, the needle may be inserted backwards during the automatic assembly process (the needle tip is inserted into the needle seat). Several defects that affect the needle are: burrs at the needle tip and backwards insertion. Among them, backward insertion will not only have a direct impact on the quality of the product, but also seriously endanger human life. As shown in Figure 1:

3. Automated detection of appearance defects in PET beverage bottles using machine vision

With the increasing market demand for disposable needles and customers' requirements for product quality, more and more medical device manufacturers are using automated needle inspection systems to conduct comprehensive inspections of the appearance defects of disposable needles. This method replaces the traditional manual method to improve production efficiency and product quality, solves the problems of low efficiency and slow speed of manual methods, as well as false detection and missed detection caused by uncertain factors such as subjective constraints of inspectors, and achieves better 100% product online inspection.

Machine vision realizes the automatic detection solution of appearance defects of disposable injection needles

This paper uses the syringe needle inspection system developed by Hangzhou Huafeng Automation System Co., Ltd. for the appearance defect inspection of disposable syringe needles. The system is based on the Siemens image processor [3] and is combined with Siemens automation equipment to form a system with both simple digital signal interfaces and complex industrial network interfaces, allowing users to choose a system that suits their working conditions, which is both convenient and saves investment.

The basic detection and processing flow is shown in Figure 2, and the simplified system framework is shown in Figure 3:

Working principle: First, the injection needle is sensed by the optical fiber sensor, and then the image processor is triggered to take a picture. After the image is collected, the image is subjected to image analysis and processing such as binarization, target positioning, measurement, and feature matching. The processing results are transmitted to the PLC for logical control, and the rejection device is driven according to the current speed of the conveyor belt to accurately reject unqualified products. Considering the current needs of automated production, the current rejection method uses whole-row rejection. If a higher level of automation is required, a suction cup can be installed for each needle holder.

System design features: This system uses Siemens embedded image processors, and its integrated modules make it easy to design system configuration and appearance according to the customer's on-site environment and customer requirements. The system's appearance uses all stainless steel materials, which meets the specifications of the medical device industry; the independent mechanical structure is easy to install at any position on the assembly line; through the connection between Siemens touch screen and PLC, it is easy for operators to switch programs of different products online, and can view real-time detection data from the touch screen; according to the diversification of products on a single assembly line, the system uses an XYZ adjustable mechanical mechanism to make user operation more flexible.

4 Conclusion

The system has been successfully used in the production line of a well-known domestic medical device company, with very good results, with a missed rejection rate of 0 and a false rejection rate of 99.99%. It not only meets the existing needs of users, but also reserves a lot of functions and upgrade space for users. These functions will play a greater role in future detection tasks, solve more problems for users, and save a lot of upgrade costs. Such as: printing interface, host computer communication interface, alarm interface, needle tip burr detection function, speed-up function, etc. More importantly, the system can strictly control the quality of user products and reduce a lot of labor costs. With the continuous improvement of industrial automation level and the increase of labor costs, the application prospects of this system will be broader.