Assembled drilling tool

Abstract

An assembled drilling tool has a drilling bit ( 2 ) connected with a drilling stem ( 1 ) through a drilling bit joint ( 3 ). The drilling stem is connected by drilling stem sections ( 11 ). Each drilling stem section includes an inner stem section ( 111 ) and a hollow outer stem section ( 112 ). The inner stem section is rotatably fixed in the outer stem section. The inner stem sections are connected together to form inner stem ( 11′ ) of the drilling stem, and the outer stem sections are connected together to form outer stem ( 12′ ) of the drilling stem. The inner stem is connected with an output shaft of a power machine, and the outer stem is fixedly connected with the shell of the power machine. The length of the drilling stem of the assembled drilling tool can be arbitrarily adjusted, and the drilling bit can be rotated with high speed without friction generated between the drilling stem and the hole wall, thereby improving the speed and the efficiency of hole drilling.

1 . An assembled drilling tool comprising a drilling stem, a drilling bit and a drilling bit joint, the drilling bit being connected with the drilling stem through the drilling bit joint, characterized in that, the drilling stem is formed by connecting drilling stem sections each of which includes an inner stem section and a hollow outer stem section, and the inner stem section is rotatably fixed in the outer stem section, the inner stem sections of each of the drilling stem sections are connected together to form inner stem of the drilling stem, the outer stem sections are connected together to form outer stem of the drilling stem, and the inner stem of the drilling stem is connected with the output shaft of a power machine, and the outer stem is fixedly connected with the shell of the power machine. 
     
     
         2 . The assembled drilling tool according to  claim 1 , characterized in that, the drilling bit joint comprises an inner joint and a hollow outer joint, the inner joint is rotatably mounted within the outer joint, the inner joint is connected with the inner stem of the drilling stem at one end and with the drilling bit at the other end, and the axial force and the radial force of the drilling bit are delivered to the outer joint through the inner joint, and the outer joint is connected with the outer stem of the drilling stem. 
     
     
         3 . The assembled drilling tool according to  claim 2 , characterized in that, the inner stem sections of the drilling stem sections are mounted within the outer stem sections through a bearing, and the inner stem sections are coaxial with the outer stem sections and formed with a center hole. 
     
     
         4 . The assembled drilling tool according to  claim 3 , characterized in that, the inner joint of the drilling bit joint is mounted within the outer joint through a bearing, and the inner joint is coaxial with the outer joint and formed therein with a through hole which is in communication with the center hole. 
     
     
         5 . The assembled drilling tool according to  claim 4 , characterized in that, the bearing of the drilling stem section comprises two bearings, keeping concentric, and the bearing of the drilling bit joint comprises one axial bearing bearing an axial force and two radial bearings bearing a radial force and keeping concentric. 
     
     
         6 . The assembled drilling tool according to  claim 5 , characterized in that, the two bearings keeping concentric are self-aligning ball bearings respectively provided at two ends of the inner stem sections, the axial bearing is a thrust ball bearing, and the two radial bearings are self-aligning ball bearings at two sides of the axial bearing. 
     
     
         7 . The assembled drilling tool according to  claim 1 , characterized in that, the inner stem sections of the adjacent drilling stem sections of the drilling stem are connected together through a thread or tongue-and-groove structure, and the outer stem sections are connected together through a thread or tongue-and-groove structure. 
     
     
         8 . The assembled drilling tool according to  claim 7 , characterized in that, the inner stem of the drilling stem is connected with the inner joint of the drilling bit joint through a thread or tongue-and-groove structure, and the outer stem is connected with the outer joint through a thread or tongue-and-groove structure. 
     
     
         9 . The assembled drilling tool according to  claim 8 , characterized in that, the inner stem section of the drilling stem section of the drilling stem is a square groove at one end and is a square head at the other end, and the square head can be inserted into the square groove, the outer stem section of the drilling stem section is an inner thread at one end and is an outer thread at the other end, and the outer thread can be screwed into the inner thread. 
     
     
         10 . The assembled drilling tool according to  claim 9 , characterized in that, the inner joint of the drilling bit joint is a square groove at one end, the square head at one end of the inner stem of the drilling stem can be inserted into the square groove at one end of the inner joint, the outer joint is an inner thread at one end, and the outer thread at one end of the outer stem of the drilling stem can be screwed into the inner thread at one end of the outer joint. 
     
     
         11 . The assembled drilling tool according to  claim 10 , characterized in that, the outer joint of the drilling bit joint is further provided with a plug at the other end, the plugs is fixed at the outer joint through a thread, a sealing ring is provided between the plug and the inner joint, the inner joint is provided with a step at the outer surface, and the step abuts against the axial bearing. 
     
     
         12 . The assembled drilling tool according to  claim 1 , characterized in that, the inner stem sections of adjacent drilling stem sections of the drilling stem are connected together through an inner stem joint, and the outer stem sections are connected together through an outer stem joint. 
     
     
         13 . The assembled drilling tool according to  claim 12 , characterized in that, the inner stem of the drilling stem is connected with the inner joint of the drilling bit joint through the inner stem joint, and the outer stemma is connected with the outer joint through the outer stem joint. 
     
     
         14 . The assembled drilling tool according to  claim 13 , characterized in that, the inner stem sections and the inner joint are connected with the inner stem joint through a thread or tongue-and-groove structure, and the outer stem sections and the outer joint are connected with the outer stem joint through a thread or tongue-and-groove structure.