Chalk sleeve barrel

The utility model relates to a chalk of a teaching apparatus, in particular to an extractable chalk sleeve comprising a bracket, a base and a median bundle. The bracket is provided with a tray and extended downwards to form a double-screw bolt. The side of the double-screw bolt is provided with a leading portion. The hollow pipe-type median bundle is provided with a leading hole at the location corresponding to the leading portion on the side wall and provided with a clamping portion at the bottom. The base inside is provided with a double-screw bolt canister at the middle location. The double-screw bolt canister is provided with a bolt portion matched to the double-screw bolt. The base inside is provided with a clamping portion corresponding to the clamping portion of the median bundle, wherein the bracket is arranged in the median bundle pipe. The leading portion of the bracket is just positioned in the leading hole of the median bundle. The double-screw bolt of the bracket is connected with the double-screw bolt canister of the base and positions the median bundle in the base by mean of the clamping portion. The utility model resolves the technical problems that the prior chalk device uses a propelling way through the sliding groove and propelling rod, not only with force, but also the propelling rod is not easy to propel to the right position for location.