JPS6337578Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improved diaphragm for a diaphragm valve, and in particular to a high-strength diaphragm that has excellent wear resistance against slurry and also has vacuum resistance and pressure resistance.

A diaphragm valve is a valve that opens and closes a dam part of a valve body using a diaphragm made of a rubber-like elastic material, and its purpose is to circulate and shut off fluid, and its structure is simple and the opening and closing are reliable. Therefore, it is widely applied to transportation piping for various fluids.

However, the diaphragm of conventional diaphragm valves is used for transporting solid particles such as ore together with liquid through pipes in mines, or for discharging sand, mud, etc. along with water during civil engineering work.
In addition, when applied to so-called slurry-like fluids, such as when solid particles such as gypsum are mixed with liquids such as water and transported through pipes in factories, wear problems due to the solid particles of the slurry persist, and moreover, they are operated under high vacuum or under high pressure. The bottom will not be deformed or damaged,
There are problems such as having to achieve sufficient reliable flow and blocking effects, and in particular, there is significant wear and deformation due to vacuum pressure in the case of suction piping and high delivery pressure in the case of pressure transportation by pumps. Due to the harsh operating conditions in which the diaphragm tends to develop, it has the inherent disadvantage of requiring frequent replacement of the diaphragm.

For example, a diaphragm made of homogeneous natural rubber with a hardness of 60° to 70° has a service life of only 10 days due to wear. In addition, when the same diaphragm was tested for decompression strength at 750 mmHg, there was no abnormality in the material, but the seal was found to be defective.

Therefore, when we tested a diaphragm made of monolithic and homogeneous natural rubber with a hardness of 40° to 50°, the service life due to wear was extended to 108 days.
In terms of decompression resistance, deformation occurred under reduced pressure of 500 mmHgmH, making continued use impossible.

As a result of conducting such tests extensively, the present inventor discovered the following fact.

Originally, diaphragm wear occurs when the fluid to be treated flows like a torrent between the diaphragm and the dam of the valve, especially just before the valve closes or when the valve is half-open, and at that time, the fluid-contact surface (lower part) of the diaphragm The solid particles in the fluid rub against each other violently, resulting in severe and rapid wear. By the way, as common technical knowledge, it is believed that only forming an extremely hard inner layer, such as hard chrome plating on the inner surface of the cylinder liner of an internal combustion engine, can achieve the most effective anti-wear effect. Ta. As a result of testing, we found that, for example, a diaphragm made of rubber with a hardness of 75 degrees wore out so severely that it became unusable after just a few days. Therefore, we switched to a model whose fluid-contact surfaces were made of significantly softer rubber, and found that it could be used continuously for about 6 months without the need for replacement.

However, if the entire diaphragm material is made of a relatively soft material, it will naturally not be able to withstand the pressure during slurry feeding as described above.

The purpose of this invention is to provide a diaphragm for a slurry feeding diaphragm valve that can withstand the contradictory and harsh usage conditions mentioned above for a long period of time. The structure of this device is that the part in contact with the fluid is made of a rubber-like elastic material layer with a hardness of 40° to 50° as measured by a shoal length meter, and the part not in contact with the fluid has a hardness of 60° to 70° as measured by a shoal length meter. This diaphragm for a diaphragm valve used for transporting a slurry-like fluid is characterized in that it is made of a rubber elastic layer of the same type as a certain fluid-contacting part, and that these two layers have an integral structure.

The present invention will be explained below with reference to the drawings.

In the diaphragm 1, the non-fluid contact layer 3 has an upward protrusion 5 in which the head of the bolt 2 is embedded;
The rubber-like elastic body has a hardness of 60° to 70° as measured by a shoal sillometer, and the fluid contact layer 4 is made of a rubber-like elastic body that has a hardness of 40° to 50° as measured by a shoal sillometer. has been done. Diaphragm 1
The thickness of the fluid contact layer 4 and non-fluid contact layer 3 is not particularly limited, but the non-fluid contact layer 3 is approximately 2/3 of the total thickness.
~3/4, and the fluid contact layer 4 occupies about 1/3 to 1/4 of the remaining portion, which is very good. The diaphragm 1 is composed of the upper and lower two layers 3 and 4.
4 Both layers are integrally molded without bonding each layer.

The rubber-like elastic body that is the material of the diaphragm according to the present invention includes natural rubber and synthetic rubber. Examples of synthetic rubber include diene rubbers such as butadiene rubber (SBR, NBR), isoprene rubber, and chloroprene rubber; Examples include olefin rubbers such as butyl rubber, EPT, and chlorosulfonated polyethylene (CSM). However, it goes without saying that an appropriate amount of filler such as carbon may be mixed in if necessary. In addition, for each diaphragm, both layers use the same type of rubber rather than different types of rubber. By using the same kind of materials in this way, strong adhesion between both layers 3 and 4 that cannot be peeled off is ensured. This is extremely convenient because it ensures non-separable adhesion between both layers 3 and 4.

The other components of the diaphragm valve shown in FIG. 1, in which the diaphragm of the present invention is incorporated, are not particularly different from those of the conventional one, so they will only be shown in the drawings and detailed explanations thereof will be omitted. In addition,
The dam 6 of the valve body is a protrusion inside the valve that cooperates with the diaphragm 1 to achieve a fluid flow blocking effect.

Incidentally, in order to provide a more thorough understanding of the structure of the present product, examples of the manufacturing method will be described, but these are merely examples and are not intended to limit the present invention to these examples.

Manufacturing Example This is divided into an A process and a B process. Step A involves semi-vulcanizing and pre-molding a layer with a hardness of 40° to 50°, in which an appropriate amount of natural rubber with low blended carbon is taken, placed in the required mold, and treated at a temperature of about 100°C for 10 minutes. In this case, it is recommended to use a smaller amount of process oil than usual in order to achieve so-called "spreading."

This pre-processing is done by:
This is because when molding and vulcanizing the high-hardness layer in the subsequent step B, it is necessary to make both layers adhere well and match the dimensions.If semi-vulcanization is not performed, the adhesion between the two layers will be poor and uneven thickness will occur. There are many.

Next, in the B process, the semi-vulcanized layer made in the A process and the same type of rubber with a high carbon content are simultaneously sandwiched between them with a rough cloth (for example, coarse cold sand) that has been treated with an adhesive. Perform molding and vulcanization. The process is carried out in as many steps as possible, as illustrated in the graph of FIG. 135°~145°C to 165°~170
℃ in 2 steps or 3 steps as shown in the figure over 25 to 30 minutes. In the latter case, the intermediate temperature may be something that can be estimated from the graph.

The product thus obtained will last for 4-6 months.
There was no need to replace it, it could be used continuously, and there were no leaks. It was a truly astonishing achievement.

In addition, the cloth interposed in the middle may be omitted,
In any case, the materials of both layers penetrated and mixed with each other at the interface between the two layers, exhibiting a tight bond, and did not peel off during use. Therefore, what is shown in FIG. 2 is merely a schematic diagram, and does not mean that the two layers show a clear dividing surface.

In addition, in this invention, the reason why the hardness of the rubber-like elastic body used in the fluid-contact parts is defined as 40° to 50° by a shoadyrometer is that if the hardness is greater than 50°, the hardness is determined by the slurry of the rubber-like elastic body. This is because the wear becomes extremely large, and if the hardness is less than 40°, the wear becomes even more severe and it becomes unusable.

Similarly, the reason why the hardness of the rubber-like elastic body used in non-fluid contact parts is specified as 60° to 70° is that if the hardness is greater than 70°, the vacuum resistance and pressure resistance are excellent, but
On the other hand, the sealing performance becomes very poor, and on the other hand, if the hardness is less than 60°, the vacuum resistance and pressure resistance will be lower than the hardness of 60°.
This is because it is 20 to 50% worse than the 70° angle. This product can also be used in diaphragm valves that control gaseous fluids containing fine particles.

As described above, the diaphragm for the diaphragm valve of the present invention has sufficient strength against deformation or destruction even under high vacuum or high pressure due to the non-contact part, and also has sufficient strength against deformation or breakage even under high vacuum or high pressure. A diaphragm can be obtained that can withstand wear caused by particles, can achieve reliable sealing when the valve is closed, and ensures strong, non-separable adhesion between the fluid-contacting part and the non-fluid part.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view of the diaphragm valve.
FIG. 2 is a schematic vertical cross-sectional view of the diaphragm, and FIG. 3 is a graph showing the heating mode in the final step of manufacturing the diaphragm, with temperature on the vertical axis and time on the horizontal axis. In these figures, 1... diaphragm, 2...
Bolt, 3... Non-fluid contact part, 4... Fluid contact part, 5... Bolt fitting projection, 6... Weir part.

Claims (1)

[Scope of utility model registration request] The hardness of the parts in contact with fluid is determined by a shoadilometer.
The non-fluid-contact part is made of a rubber-like elastic layer of the same type as the fluid-contact part and has a hardness of 60-70° as measured by a shoadyrometer, and these two A diaphragm for a diaphragm valve used for transporting slurry fluid, characterized by having an integral structure of layers.