Design and experiment of intelligent fixture for cutting breeding cocoons of bombyx mori

Abstract: In China, silkworm raisers have to hire workers to cut breeding cocoons of bombyx mori manually, as domestic cocoon-cutting machines have been technically immature until now. The reported cutting machines and devices for breeding cocoons of bombyx mori cannot be used practically because the cutting mechanism is unable to locate the cocoons accurately for the clamping mechanism and is incapable of adjusting the posture of the cocoons and the clamping force of the fixture. As traditional fixtures are not applicable to clamp cocoons with different sizes and shapes in cutting, we designed an intelligent fixture. It works as follows: when a cocoon is dropped into the intelligent fixture in any posture, it will be immediately accurately detected by the detecting mechanism. Then, the actuator is dictated to adjust the posture of the cocoon, and to regulate the clamping force of the fixture by the control system. As a result, the cocoon is adjusted to be upright and firmly fixed. When the fixed cocoon is cut along the top surface of the fixture by the cutting device, the cut is flat and moderate, so the silkworm chrysalis can easily be separated from the cocoons without being hurt. Ten kinds of hybrid cocoons were randomly selected to be experimental samples, each five kilograms, such as Furong×Xianghui, Chunlei×Zhenzhu, 871×872 etc. 400 cocoons of each variety were randomly sampled to be tested by the intelligent fixture one by one. In addition, the fixing results, the cutting results, and the whole time were recorded when each cocoon was tested. Experimental results showed that the intelligent fixture can be used for clamping different kinds of cocoons with different sizes and shapes. About 98% of the selected cocoons can be adjusted to an appropriate location and fixed firmly by the intelligent fixture. When the intelligent fixture worked with the cutting device, the success rate of cutting was greater than 97%, and the injury rate of pupa was lower than 2%. Besides, it took 6-8 seconds from the time a cocoon fell into the jig to be cut successfully. In conclusion, the intelligent fixture can be used for clamping different kinds of breeding cocoons of bombyx mori in a cutting machine.