JPH03287363A - Valve seat fitting device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention is an apparatus for repairing a valve seat surface of a gate valve, a check valve, etc. by polishing according to its condition, and inspecting the condition of the valve seat surface. This invention relates to a valve seat grinding device that enables dry polishing of the valve seat surface without repairing or replacing the polishing head.

[Conventional technology]

Conventionally, many gate valves, check valves, etc. have been used in power plants, especially nuclear power plants. During plant operation, there is a possibility that foreign matter such as scale present in the piping may adhere to the valve seat surface. If the valve is opened or closed with this adhesion, these foreign matter may damage the valve body or valve seat. It digs into the sheet surface, causing scratches and impressions. In addition, erosion due to fluid flow may cause uneven wear, and thermal deformation may cause distortion. If the degree of sealing at the valve seat surface becomes incomplete due to these factors, it will have an adverse effect on the plant. Therefore, for example, especially in the case of nuclear power plants, it is mandatory to shut down the entire plant and conduct periodic inspections once a year. Inspection and repair work involves stopping the plant and isolating the system if necessary, so it is particularly desirable to shorten the period of this work in order to increase the operating rate of the plant. The conventional work is roughly as follows. After removing the valve drive unit, taking out the valve body, and disassembling it, skilled workers work in pairs to stand near the valve flange and visually inspect the valve seat surface using a pilot, ξler, etc. The polishing process is carried out using a special air-driven tool. This special tool has sandpaper glued to the front of the polishing head, and is used by rotating and pressing it against the valve seat surface.

[Problem to be solved by the invention]

With conventional techniques, the work itself requires skill and takes a long time, so workers are exposed to large amounts of radiation during this time, especially in the case of nuclear power plants. For this reason, replacement personnel are required, and with the increase in the number of nuclear power plants, securing both the quality and quantity of workers has become a major issue recently. The application of robot technology has been considered to address this issue. However, at present, nuclear power plants in particular are built extremely compactly to reduce construction costs, with the assumption that regular work will be carried out by humans.
Both passages are very narrow, and there are many stairs and ramps. Therefore, with current robot technology, it is impossible to have a valve seat adjustment robot automatically or remotely perform all tasks such as transportation within the plant, disassembly and assembly of valves, and inspection and repair of the valve seat surface. It is. Therefore, the disassembly and assembly of the valve, the transfer of the valve seat alignment device, and the assembly and disassembly of the valve seat into the valve box are performed manually, and the polishing and repair of the valve seat surface and inspection work are automated or performed by remote control. has been strongly requested. By the way, with conventional special tools for polishing, it is necessary to reapply the sandpaper used as the abrasive material to change the particle size due to clogging, etc., during the polishing work of one valve, which simply increases the work time. This is not only unfavorable from the standpoint of automation of the valve seat adjustment device. In addition, it was considered to use abrasive grains in paste form instead of sandpaper, or to mix the abrasive grains into a liquid, but this would require a means to supply and collect the abrasive grains, which would require the entire equipment. Not only is this complicated, but another problem arises in that it increases the amount of radioactive waste, especially when used as a valve seat adjustment device for nuclear reactors. The object of the invention is to overcome the problems of the prior art and to enable the valve seat surface of at least one valve to be polished without repair or replacement of the polishing head, in particular for remote control or automatic operation. In addition to overcoming one of the bottlenecks in realizing equipment capable of It is an object of the present invention to provide a valve seat alignment device that can realize reductions in the amount of air.

[Means to solve the problem]

In order to solve this problem, the valve seat grinding device according to the present invention includes a grinding head for the valve seat surface, and includes a grinding wheel made of a predetermined material and having a grain size fixed to one surface of a rigid solid member. is configured to be replaceably fixed to the substrate of the polishing head.

[For use]

A polishing head in which a grindstone made of a predetermined material and having two grain sizes is fixed to one surface of a rigid solid member is replaceably fixed to a substrate.
The polishing of the valve seat surface of at least one valve does not require replacement and can be used in a dry manner.

【Example】

Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side sectional view of the polishing unit in this embodiment, FIG. 2 is an exploded perspective view of the polishing head in this polishing unit, and FIG. 3 is a perspective view of the valve seat adjustment device for gate valves in this embodiment. be. First, the overall structure of this gate valve valve seat alignment device will be explained with reference to FIG. 3, and then the subject matter related to the polishing head will be explained in detail based on FIGS. 1 and 2. In Fig. 3, 71 is the valve box of the gate valve, 72 is the valve seat,
The components of this valve seat adjustment device for gate valves are roughly divided into polishing units 1. There are three parts: an inspection unit 21 and a bridge unit 41. The polishing unit 1 has a function of polishing the seat surface of the valve seat 72, and the inspection unit 21 has a function of inspecting the seat surface of the valve seat 72. Further, the frame unit 41 supports the polishing unit 1 and the inspection unit 21, and also has the function of moving and installing the gate valve at a predetermined position relative to the valve box 71 according to each operation. The basic operations of the frame unit 41 are three operations: simultaneous rotation of the polishing unit 1 and inspection unit 21, horizontal movement or horizontal movement, and movement of selectively raising and lowering each unit. Now, the polishing unit 1 is provided with a polishing head 2 at its tip, and the seat surface of the valve seat 72 is polished by this polishing head 2. Further, an inspection head 22 is provided at the tip of the inspection unit 21, and the inspection head 22 allows the valve seat 7 to be
2. Inspect the sheet surface. Further, a lifting motor is provided on the upper part of the polishing unit 1 and the inspection unit 21, respectively, and each motor is connected to the polishing head 2. The inspection head 22 is vertically lowered to a position opposite the seat surface of the valve seat 72 and returned to its original position after each operation. Now, in FIG. 1, reference numeral 2 denotes a polishing head for polishing, which is fixed to the left shaft end of the main shaft 11 via a universal joint 10. 1
A gear case 2 pivotally supports both ends of the main shaft 11, and has a cylindrical body 14 provided in a direction substantially perpendicular to the main shaft 11. This cylindrical body 14 allows a motor shaft 13 coupled to the main shaft 11 to pass therethrough through a set of bevel gears, which are not numbered. The cylindrical body 14 is swingably connected by a fulcrum shaft 15 to the lower part of a case 19 that houses the polishing motor 16 and other members. A pneumatic cylinder 17 is provided on the inner surface of the clay wall of the case 19, and its piston portion is connected to a polishing motor 16 fixed to the cylinder via a pressurizing lever. The operation of this polishing unit 1 is as follows. The rotation of the polishing motor 16 is transmitted to the main shaft 11 via a bevel gear, and the polishing head 2 is attached to the left shaft end.
Polish the valve seat surface. In addition, the pneumatic cylinder 17
, the polishing motor 16 is activated via the pressure lever 18.
is inclined with respect to the case 19, and the pressing force of the polishing head 2 against the valve seat surface is adjusted. Next, the polishing head 2 will be described with reference to FIG. In FIG. 2, the circumference of the disc-shaped hand board 9 is 8
A grindstone groove 9a is formed in the radial direction from the equally dividing position (only one location is shown with a solid line), and the grindstone piece 8 is fitted into this grindstone groove 9a. The grindstone piece 8 is a member having a base material made of a block of metal material having a convex cross section, and a grindstone fixed to the upper surface of the convex portion. The fitted grindstone piece 8 is fixed to the head base plate 9 from both sides by a pressing plate 7 and a pin 5, or only a slight movement in the right angle direction is allowed. Note that a bottle 7a is attached to the outer end of the presser plate 7, and the outer periphery of the bottle 7a is in contact with the outer end surface of the grindstone piece 8.
Further, the cap screw 6 is screwed into the grindstone groove 9a from the back side, and its outer threaded portion contacts the inner end surface of the grindstone piece 8. In other words, the grinding wheel piece 8 is attached to the bottle 7 at each of its outer and inner end surfaces.
It is held between the outer peripheries of a and the presser screw 6 to prevent it from flying out due to centrifugal force and from moving due to unexpected external force. Further, the material and grain size of the grindstone fixed to the grindstone piece 8 are selected depending on the material of the valve seat and the condition of the seat surface. At the same time, an appropriate bonding agent must be selected. Normally, for general polishing, a vitrified grindstone is used, which is made by sintering silicon carbide abrasive grains with ceramics, and if you want to increase the polishing efficiency by rotating at a relatively high speed, you can use a vitrified grindstone with silicon carbide abrasive grains made of plastic. A hardened resin bond type whetstone is selected for each. However, the above-mentioned selection criteria are only a guideline, and in reality, selection criteria are often determined empirically according to the condition of the seat surface of the valve seat. In any case, by using the whetstone piece 8 equipped with a whetstone made of materials and two grain sizes, as described above, unlike the conventional sandpaper, the abrasion of the whetstone is greatly reduced, and at least one There is no need to replace the valve seat surface of the valve until polishing is completed, and dry polishing becomes possible. In the embodiment described above, a so-called divided grindstone method was adopted in which eight grindstone pieces 8 are replaceably attached to the front of the head substrate 9. Instead of this, in order to simplify the attachment and detachment of the grindstone, a system may be adopted in which one donut-shaped grindstone plate corresponding to the valve seat seat surface is attached. Replacement, especially when used for nuclear reactors. Since the amount of discarded tools is a problem, the former method of dividing the grindstone is superior. In FIG. 2, after all the grindstone pieces 8 are first attached to the head substrate 9 and after a predetermined polishing operation, it is necessary to adjust the grindstone surface by dressing them on a surface plate. Furthermore, when the wear of the grindstone surface reaches a predetermined level, it is natural that the grindstone piece 8 must be replaced or discarded.

【Effect of the invention】

As explained above, in the present invention, a predetermined material is fixed to one surface of a rigid solid member. A polishing head in which a grindstone of a certain grain size is replaceably fixed to a substrate can be used in a dry manner without having to be replaced for polishing the valve seat surface of at least one valve. Therefore, the present invention has the following superior effects compared to the conventional technology. (1) It is possible to shorten the total working time and improve the operating rate of the plant. (2) The polishing head is compact, lightweight, and has good portability, which directly leads to a reduction in operating costs. (3) In relation to items (1) and (2) above, one of the major bottlenecks to automation of polishing work is overcome and automation is promoted. (4) Particularly in relation to item (3) above, it is possible to reduce the number of working personnel, and in particular, the problem of securing skilled workers can be solved. (5) Fewer tool parts need to be replaced or discarded, and the work is dry, which reduces radiation exposure, reduces the amount of radioactive waste, and makes it easier to dispose of, especially in nuclear reactor-related plants. , is effective in ensuring safety and solving social problems.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a polishing unit according to an embodiment of the present invention, FIG. 2 is a diffusion exploded perspective view of a polishing head in this polishing unit, and FIG. 3 is a perspective view of an embodiment of the present invention. Description of symbols 1: Polishing unit, 2: Polishing head, 7: Holding plate, 8: Grinding wheel piece, 9: Head substrate, 9a: Grinding wheel groove, 72: Valve seat. Figure 1

Claims (1)

[Claims] 1) In an apparatus equipped with a polishing head for the valve seat surface, a grindstone of a predetermined material and grain size fixed to one surface of a rigid member is configured to be exchangeably fixed to the substrate of the polishing head. A valve seat alignment device characterized by: