Patent Number: 052710467
Section: summary

CROSS-REFERENCE TO RELATED APPLICATION This application is a Continuation of International application Ser. No. PCT/DE91/00430, filed May 23, 1991. The invention relates to a manipulator for working in a connection-piece or pipe region of a vessel of a primary loop in a nuclear power plant, particularly for non-destructive testing. The invention also relates to a process for maneuvering an appliance, in particular a test head. The lines of the primary loop of a nuclear power plant are introduced into the pressure vessel through connection pieces and are joined by welding. Since the connection-piece region is one of the points under heavy strain, it is tested at regular intervals by non-destructive methods. It is known to carry out such tasks with a manipulator that has an outrigger being disposed radially to the connection piece and having a test head being radially displaceable on the outrigger and being rerailed on an annular rail that surrounds the connection piece to be tested. In order to carry out the necessary motions in the testing operations, the manipulator has one drive in the circumferential direction of the connection piece and one drive in the radial direction. Through the use of mechanical devices, the outrigger in the radial direction is pressed against an outer vessel wall to be tested and is aligned tangentially. The vessel with the connection piece is surrounded by a biological shield and an insulation. Due to the fact that a gap between the vessel and the insulation or biological shield is sometimes very narrow, it is very difficult and not always possible to introduce the known manipulator into the annular gap, since the necessary structural height of the known outrigger prohibits its use in the very narrow annular gap. During testing, the test head must be moved around the connection piece over concentric or elliptical paths. For technical testing reasons it is necessary to use various test heads, which must be manually replaced in the course of a test. The testing is made more difficult by the increased radiation in the vicinity of the test specimen and by the tight spaces. Changing the test head in the known equipment requires manual disassembly of the manipulator and is therefore very time-consuming and involves considerable radiation exposure to humans. Moreover, avoiding obstacles in the test region is not always possible, since in order to move the test head, the radial outrigger has a bottom frame with a spindle extending over its entire length and therefore has a pronounced overhang. It is accordingly an object of the invention to provide a manipulator and a process for carrying out work in the connection-piece region of a vessel, which overcome the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type. The manipulator should be able to be introduced into the annular gap more easily than before and be able to work even in narrow annular gaps. Moreover, it is intended to enable the manipulator to shorten the time required for changing the test head and to reduce the radiation exposure to the human operators. The process should permit remote-controlled maneuvering of an appliance or a test head with a manipulator in tight spaces. With the foregoing and other objects in view there is provided, in accordance with the invention, in a nuclear power plant including a primary loop having a vessel with a connection piece, a manipulator for working in the vicinity of the connection piece, in particular for non-destructive testing, comprising two trolleys being moveable circumferentially of the connection piece, a jointed-shank arm disposed on the trolleys, the jointed-shank arm including two shanks each having first and second ends, hinged supports each being disposed on a respective one of the trolleys and each sup-porting the first end of a respective one of the shanks, a crown hinge joining together the second ends of the shanks, and a support for a tool or a test head being mounted on the crown hinge. In this way, a slender structural form is attained that makes it possible to us the manipulator in tight open spaces and to circumvent obstacles in the region to be tested. By adjusting the shanks, the radius of the test track or path can be decreased, which decreases the structural size of the manipulator. The manipulator is usable not only for testing purposes but also for maneuvering tasks in the connection-piece region of vessels. In accordance with another feature of the invention, the second ends of the shanks have mutually meshing toothed ring segments with center points, and the support has pivot pins mounted thereon for supporting the toothed ring segments at the center points. In accordance with a further feature of the invention, there are provided two spring means, especially pneumatic or hydraulic cylinders, each being disposed between a respective one of the trolleys and a respective one of the shanks for pressing the tool or test head against a region to be tested, and at least one angle encoder for detecting an inclination of at least one of the shanks relative to a reference plane. In accordance with an added feature of the invention, there are provided two drive motors each having a position encoder and each being associated with a respective one of the trolleys, and a control unit having an arithmetic unit and being connected to the position encoders and to the angle encoders for controlling the drive motors. In accordance with a concomitant feature of the invention, the hinged supports are cardan joints. With the objects of the invention in view, there is also provided, in a process for carrying out work in a connection-piece region of a vessel of a primary loop in a nuclear power plant with a maneuvering unit including two trolleys being moveable circumferentially of or around the connection piece, hinged supports each being disposed on a respective one of the trolleys, a crown hinge, a jointed-shank arm on the trolleys including two shanks each having one end supported in a respective one of the hinged supports and another end being joined together by the crown hinge, and a support for a tool or a test head being mounted on the crown hinge, the improvement which comprises adjusting a position of each of the trolleys with a respective drive motor; pressing the tool or test head against a wall of the vessel with spring means acting upon the shanks, especially pneumatic/hydraulic cylinders; and maneuvering the crown hinge into a predeter-mined position and/or over a predetermined path by varying the position of at least one of the trolleys with a control device acting upon the drive motors. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in a manipulator and a process for carrying out work in the connection-piece region of a vessel, in particular non-destructive testing, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.