Design and test of stock clamping mechanism for vegetable grafting

Abstract: Traditional stock clamping mechanisms usually install the integral clamping pieces which will injure the stock seeding because of the curvature of itself and also the clamping force can not be adjusted as needed. According to the weakness of vulnerability of stock seedling and un-adjustability of clamping force on a clamping mechanism of a traditional vegetable grafting machine, based on the analysis of the structure parameters and compression characteristics of cucurbit stock seedlings, a new clamping mechanism which was used in inclined-inserted vegetable grafting machine has been developed with convex and concave pieces cross-clamped. The thickness of the clamping mechanism can be adjusted by increasing or decreasing the number of clamping pieces, the clamping force of clamping mechanism also can be easily changed by adjusting the tension of spring which was installed on the clamping mechanism. Its main structure parameters such as the angle of clamping pieces were determined by establishing the mechanical model and analyzing the holding force of stock seedling on clamping pieces, the thickness of clamping pieces were determined by measuring the structure parameters of the stock seeding and the clamping force was determined by measuring the mechanical parameters of stock seeding. The angle of clamping pieces was designed to be 102°, the fillet diameter of clamping pieces is 3 mm and the thickness of each holding piece is designed to be 1 mm. The total thickness of the clamping mechanism can be adjusted by changing the number of the holding piece. Each side of stock clamping mechanism has 8 pieces of holding piece and the total thickness of the clamping mechanism is 16 mm. The clamping force was controlled in less than yield point pressure of 1.26 N. Experiments showed that the design of the V-shaped structure of the stock clamping mechanism had a good function in guiding the stock seeding which reduced the growing requirements of the stock seedlings. The success rate of the clamping mechanism which was new designed reached 100%, which increased 13.3% over that of an ordinary clamping mechanism. The injury rate of the new clamping mechanism was only 1.67%, which decreased 11.63% compared with ordinary clamping mechanism. Thus, it indicates that the new stock seedling clamping mechanism was feasible. It is convenient and fast for manual feeding due to the guidance of the clamping mechanism which was cross-clamped with convex and concave clamping pieces and it provides a reference for further research to improve the quality and optimize the parameter of clamping mechanism for the stock seeding of a vegetable grafting machine. At the same time, there was a space reserved for the automatically feeding of stock seeding which can be docked with an automatic seedlings mechanism.