The reamer is the core part of a horizontal directional drilling machine in the process of reaming. In the construction of horizontal directional drilling, it is a tool to cut and break the soil and rock along the guiding track. Expanding from the guide hole to a suitable hole diameter usually requires multi-stage reaming and multiple clearing. It can be divided into barrel reamer, plate reamer, fly-rotating reamer, gear reamer, roller reamer, and so on according to the structural characteristics.
1. Barrel reamer
Barrel reaming process on the hole wall has a certain squeeze, and wall stabilization function. Welding wear-resistant material on the outer surface of the barrel can keep the diameter and correct the well wall. Its rear cover is welded with a tungsten carbide-tipped cutter head with a large taper, which is favorable for positive reaming in the opposite direction in case of collapse.
Bucket reamer can also be divided into general bucket and runner bucket reamer, the latter adopts spiral runner groove, which is more conducive to the channelization of mud and geotechnical debris. In addition, there is a plate bucket reamer, which has the characteristics of a large cutting edge of the plate type but also has the role of the bucket reamer on the hole wall of the extrusion correction and the role of large buoyancy, expanding the hole efficiency is very high.
2. Plate reamer
Its tool body structure adopts large cutting-edge drilling, which can realize graded reaming. The hole size from 480~1625mm, and the water hole diameter is 71~76mm, the numbers 12, 20, and 24 ranging.
3. Flying Spin Reamer
It adopts cemented carbide cutting teeth, and the nozzles installed above it are interchangeable. Reaming size of 480-1625mm, water eye diameter of 76mm, the number of 12, 20, 24, and so on.
4. Gear Reamer
The gear reamer has no fixed tooth shape and bearing, so it is necessary to choose a suitable tooth shape and bearing structure according to different stratigraphic structures. It adopts palm back tilting, cold-set anti-wear alloy design, and tooth wheel anti-dislodgement structure, which mainly prevents the tooth wheel from dislodging after the tooth wheel bearing is damaged, resulting in accidents in the hole. It is suitable for horizontal directional drilling construction and is designed with high strength, good wear resistance, long service life, and good safety performance. The hole reaming size is 220~1600mm.
It mostly uses the single tooth palm and tooth wheel of the tooth wheel drill bit as 1 cutting edge, and the number of cutting edges is 3 and above, the hole reamer is composed of a rear support plate, rear baffle, mandrel, front baffle, front support ring, front support plate, tooth wheel, tooth palm and so on. it uses a welding process to connect and fix each component. The reaming process is provided by the screw drilling tool to provide torque and the drilling rig to provide tension.
Similar to oil drilling, it can be categorized into milled diagrams, inlaid according to the different types of the drill body.
(1) Milling gear reamer
It is the use of the teeth of the gear is milled teeth, that is, in the tooth wheel matrix milled teeth, its wear resistance is relatively poor. To improve the degree of wear resistance, often welded on its hard alloy layer.
(2) Gear Reamer
Its hardness, and wear resistance are good, long service life. The disadvantage is that the teeth are brittle, easy to collapse, and fall off due to inlaid teeth are not secure.
5. Roller reamer
Roller Reamer adopts a large diameter metal sealing hob design, bearing a life of up to 100 hours or more. The unique multi-stage anti-dislodgement interlocking device prevents dislodgement when the drill bit is thrown empty and dislodgement of the hob shell when the bearing is damaged. Meanwhile, it has an excellent hydrodynamic design, smooth slag discharge, and hydraulic rock breaking. The drill bit is precision forged with high-quality alloy steel, and the large drill bit body adopts weight weight-reduction design to reduce track deformation. The remaining size is 400~2000mm.
The structural characteristics of various types of reamers determine the reaming work mode, usage, and application scope, among which the barrel reamer, plate, and fly-rotating are suitable for traversing the soil layer, while the gear and roller rock are suitable for traversing the rock layer. In the horizontal directional drilling traversing project, especially the long-distance traversing project, the stratum condition is complicated, and the reamer's adaptability to the stratum is extremely important.
◆Horizontal directional drilling traversing pre-reaming should consider the following three aspects:
1. the service life of the reamer
2. the value of torque generated by the reamer at each reaming stage
3. efficiency and economy of reaming.
The advantages of the gear reamer such as strong geological adaptability, high design strength, good wear resistance, long service life and good safety performance can further improve the efficiency and quality of reaming, which is suitable for long-distance directional traversing construction. Therefore, it is extremely necessary to optimize and improve the gear reamer for long-distance horizontal directional traversing projects.
