JPS6351749B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a large bolt cleaning device, and more particularly to a bolt cleaning device suitable for cleaning stud bolts that tighten an upper mirror, which is the upper cover of a nuclear reactor pressure vessel.

When performing periodic inspections of the reactor and replacing fuel, the upper mirror must be removed. When the upper mirror is removed, water is filled in the well provided at the top of the pressure vessel to prevent radioactive contamination. will be held. In this case, the stud bolts that attach the upper mirror to the pressure vessel body also become soaked in water, causing rust, and the bolts must be cleaned before and after removing and attaching the nuts.

Figure 1 shows how to clean stud bolts. The stud bolt 3 is inserted through the flange 1a of the upper mirror 1 and is threadedly engaged with the flange 2a of the pressure vessel main body 2, and the nut (not shown) is threadedly engaged with the threaded portion 3a of the bolt 3, which is the threaded portion of the nut. . When cleaning a bolt, first, a plastic bag 4 is placed over the threaded portion 3a, and the cleaning is carried out manually by a worker who puts his/her hand into the plastic bag 4 and uses a wire brush. Wearing plastic bags is intended to prevent the scattering of radioactive dust generated during cleaning work, but the effect of preventing scattering is not necessarily sufficient, and there is a high risk that workers will be exposed to radiation internally if they inhale it. Moreover, it is difficult to collect the dust. Additionally, as more than 100 stud bolts are attached to each pressure vessel, manual cleaning takes a long time and increases the risk of exposure to radiation.

A device for cleaning large stud bolts was devised in Utility Model Application No. 58283/1983. In the device according to this invention, the wire brush is rotated in contact with the bolt screw as in the present application, but there are the following problems.

(1) The wire brush is always pressed against the stud using a coil spring 48 shown in FIG.

This forces the device to be pushed into the stud in opposing contact with the stud, which can cause cracking and damage to the stud in large studs made of special materials that are sensitive to scratches.

(2) Air is taken in from the middle of the outer cylinder of the device, and air is extracted from the middle of the outer cylinder of the device. In addition, the inner cylinder is provided with a plurality of air intake ports 3c, and the resistance to air flow is large. Dust collects at the bottom of the device.

(3) The brush 4 has approximately the same length as the outer cylinder 2. To replace the brush, remove bolts 11 and 12.
It is necessary to take out a heavy device including a rotating body from the outer cylinder, and it takes time and effort to replace the brushes.

The purpose of this invention is to eliminate the above-mentioned problems and to provide a device that automatically cleans bolts, and more specifically, to leak rust and other dust removed by a rotating brush to the outside. To provide a bolt cleaning device that can effectively remove bolts by suction without causing any problems.

In short, this invention effectively removes dust by connecting a dust suction device to the main body of the bolt cleaning device, which has a brush rotated by a motor, so that air flowing in from the air intake port passes through the bolt main body while swirling. It is designed so that it can be removed.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, a cylindrical cleaning device main body 11 is arranged with respect to the threaded portion 3a of the stud bolt 3 protruding from the flange 1a of the upper mirror so that its central axis is located on the threaded portion 3a. be.
Reference numeral 13 denotes a support disposed in an annular space formed between the cleaning device main body 11 and the threaded portion 3a, and a wire brush 12 is attached to the threaded portion 3a side.
A guide 9 is fixed to the upper end of the support 13, and the guide 9 is inserted into the engagement hole 10a of the rotary disk 10. When attaching the cleaning device body 11 to the stud bolt, the device body is suspended by the handle 7 and inserted into the threaded portion 3a.
By hanging the main body of the device, the handle 7 is pulled upward as shown in the left half of FIG. As a result, the sliding plate 8 attached to the upper part of the guide 9 slides down the slope part 10b of the rotary disk 10, and the support 13
moves in the X direction. Thereby, even if the brush 3 is hard, the entire body can be easily inserted into the threaded portion 3a. When the installation of the device main body 11 is completed, the handle 7 descends due to its own weight, and as a result, the support 13 approaches the Y direction, that is, the threaded portion 3a, as shown in the right half of FIG.

Next, reference numeral 11a denotes a base forming a part of the bolt body 11, and is attached to the upper cylindrical portion by screwing or bolting. A dust suction passage 20 is formed on this base so as to open in a direction substantially tangential to the main body of the cleaning device, and similarly, an air inlet 23 is formed in the upper part of the main body 11 so as to open in a tangential direction to the main body. I'll keep it.

In the above-mentioned apparatus, when cleaning the bolts, the bolt cleaning device is attached by the above method, and then the rotating shaft of the motor (not shown) is inserted into the engagement groove 21 formed at the upper end of the device. As a result, the support 13 is rotated by the rotational force of the motor, and the brush 12 removes rust, dust, etc. from the threaded portion 3a. At the same time, air inside the device is sucked by a suction machine (not shown). For this reason, outside air flows in through the air inlet 23, and the inflowing air descends while rotating through the threaded portion 3a and the annular space inside the main body, and is collected in the suction machine along with the dust generated by cleaning through the dust suction passage 20.

FIG. 3 schematically shows the swirling path of air, and as shown, the threaded portion 3a and the cleaning device main body 1.
1, descending through the annular space between

By implementing the present invention, radioactive dust generated during bolt cleaning can be effectively suctioned and removed without being discharged outside the apparatus, so bolt cleaning can be performed safely and quickly.

[Brief explanation of drawings]

Figure 1 is a sectional view of the stud bolt insertion part of the reactor pressure vessel, Figure 2 is a sectional view of the bolt cleaning device,
FIG. 3 is a schematic diagram of the bolt cleaning device showing the air flow path. 3... Stud bolt, 11... Bolt cleaning device main body, 12... Brush, 20... Dust suction passage, 23...
Air inlet.

Claims (1)

[Claims] 1 The lower end of the cylindrical device body has a dust suction passage, the lower end is located in the engagement hole of the rolling wheel provided at the bottom of the device body, and the engagement hole of the rotary disk through which the guide connected to the upper end is rotationally driven. In an apparatus for cleaning a large stud, a large stud is provided with a plurality of supports with brushes inserted therethrough, and when the apparatus is suspended by the handles of the supports with brushes, the supports are displaced toward the wall within the apparatus main body. By forming an inlet and a dust suction passage at the bottom, and opening these air inlets and dust suction passages in the tangential direction of the wall circumference within the bolt cleaning device main body, an air flow that swirls and descends inside the bolt cleaning device main body is formed. A bolt cleaning device for sucking dust, which uses this air flow to suction and remove dust generated during bolt cleaning.