| 主权项 |
1. A method for assembling a down-the-hole drilling apparatus, the apparatus comprising a drilling device comprising a casing and a drilling unit, the drilling unit comprising a drilling head comprising a drilling arrangement, the drilling arrangement comprising a first drilling member configured to drill a center hole and a second drilling member configured to ream the center hole for the casing part, the first drilling member and the second drilling member being coupled at least during drilling mutually in a power transmitting manner in order to cooperate for at least one of a rotational motion, a feeding motion or a hammering motion, and removably coupled in connection with the casing to enable at least removal of the first drilling member from a drilled hole, whereby the casing is arranged to be pulled into the hole to be drilled by the drilling unit through a shoulder arrangement arranged at an end of the casing, and, whereby at an opposite end of the drilling arrangement with respect to a drilling surface of the drilling unit is arranged a built-in skirt, the skirt comprising in a radial direction an internal shoulder arrangement for pulling the casing into the hole to be drilled by co-operation of the internal shoulder arrangement and the external shoulder arrangement being arranged at the end of the casing, the method comprising:
manufacturing the internal shoulder arrangement in connection with the second drilling member to have an inner diameter essentially larger than the outer diameter of the corresponding external shoulder arrangement of the casing; and forming a mutual joint between the second drill member and the casing that transmits a pulling force in a longitudinal direction by placing the shoulder arrangements on top of each other, to overlap one another and by shrinking the internal shoulder arrangement in the longitudinal direction behind the external shoulder arrangement. |
