The gripper of the full hydraulic tunnel prospecting rig is an important executive assembly of the main engine. When drilling, lifting, pulling and torsional unloading of drill pipe, it is necessary to work together with chuck, gripper and feeding device.

According to the principle of the system, the gripper of the tunnel drill adopts a normally closed design, which needs to rely on the pre-compression of elastic components such as springs and disc springs to provide the clamping force, and the disc spring is continued to be compressed by high pressure oil to open the gripper and realize the clamping and opening action.

The structure principle of the normally closed gripper is simple, the cost is low, the maintenance is simple, these brief introduction is not enough to summarize the advantages of the normally closed gripper. In an aside, what is one of the advantages that the fully hydraulic tunnel prospecting rig has not been replaced and surpassed by other drilling rig products so far? The answer is: mechanical twist discharge of drill pipe, drill feeding and drill lifting, reducing manual labor, improving work efficiency, making drill products more humane. To get to the point, without the existence of the normally closed gripper, the above functions of the tunnel drill can not be realized, and a different form of gripper subverts the hydraulic system principle of the full hydraulic drill. Therefore, the normally closed gripper is also an important research achievement in the geological exploration industry, the rope coring drill and the geological exploration drill manufacturing industry in the mine, and it is also a research topic with expansion and extension value, which is worth in-depth study, otherwise the development of the full hydraulic tunnel prospecting drill will encounter technical barriers.

So what are the disadvantages of the normally closed gripper? Of course, after all, the clamping force is provided by the pre-loading force of the elastic elements such as the disc spring, the structure of the clamp, the size of the clamping force is limited by the specifications and sizes of the elastic elements such as the disc spring, and it is not like the clamping force provided by the hydraulic pressure, which can be adjusted by the diameter and pressure of the cylinder, and how much you want to design according to the demand.

Speaking of this, we can explain a phenomenon, in a very complete, not hard formation why the large, so-called "full hydraulic" portable drill product penetration efficiency is fast, and can hit so deep, and the full hydraulic tunnel prospecting drill in a good formation is difficult to hit this portable "limit" depth? Penetration efficiency is achieved by high speed and thin wall drill pipe, drill tool and the application of mud lubrication materials, here not to mention, the full hydraulic tunnel drill can be achieved if it does not consider the drilling ability of complex geological conditions. Speaking of the drilling depth under particularly good geological conditions, because the portable drilling rig does not need hydraulic linkage, the clamp relies on hydraulic clamping force, no matter how deep, you can design a large enough cylinder and reasonable pressure to meet the needs of reliable clamping force, and the normally closed clamp is restricted in this respect.

An indispensable factor in deep hole drilling is the clamping force of the gripper. Full hydraulic tunnel drilling rig technology in a comprehensive development, comprehensive promotion, in the scope of its drilling capacity reflects its unparalleled superiority, but in the future, China's geological exploration field will continue to develop, which requires the tunnel drilling rig products in technology to have innovation, of which the gripper is a crucial link.

In December 2022, the double-action gripper independently developed by Chifeng Jiexing Drilling Equipment Manufacturing Co., LTD. (Chifeng Jiexing Drilling Machine Factory) improved the clamping force of nearly 40% on the basis of the traditional normally closed gripper, and the clamping is reliable and the linkage is sensitive, making the tunnel drilling machine manufacturing industry take a small step forward.