How to deal with the surface hardening of CKD solenoid valve?
Due to the use of superhard materials or surface hardening treatments (≥ 45 HRC/≥ 950 HV) on the sealing surfaces of metal hard CKD solenoid valves, they cannot be machined with ordinary tools, and even if they can be machined, their machining accuracy cannot meet the requirements. Therefore, it is very important to choose suitable tools for machining.
The precision grinding of CKD solenoid valves generally uses a specially designed grinding machine, which is mainly composed of a rotating shaft that clamps the ball and a grinding head. The composition of the grinding head mainly consists of a centering flange (connecting plate) connected by a shaft, a spring floating mechanism, a grinding strip clamping plate, and a grinding strip. The grinding strip can be made of various materials such as oilstone sand strips or synthetic diamond materials according to the surface treatment method of the sphere.
The base material of CKD solenoid valve seat should be made of stainless steel material with a linear expansion number close to that of the shell material. The hardening treatment process of the sealing surface can also use manual welding or plasma spray welding of hard alloy. The final thickness of the weld overlay should be
Usually, the metal hard sealed CKD solenoid valve seat sealing surface is precisely ground with the ball using the planetary grinding principle on a specially designed grinding machine, and then manually matched with the ball one-on-one for inspection using indentation method.
The inlet and outlet of the product are interconnected, and a disc spring is provided on the upstream valve seat of the product near the inlet end face. The disc spring of the product is located between the upstream valve seat and the valve body of the product. The valve body of the product is equipped with a sealing platform, and the sealing platform of the product is at a predetermined distance from the upstream valve seat of the product. This product provides a hard sealed floating ball valve that can achieve bidirectional sealing, reducing costs and simplifying operational complexity. In addition, this product can achieve reverse sealing while ensuring flow sealing, and can meet the sealing requirements of high and low pressure states; This product ensures the reliability of reverse sealing by setting up a sealing platform.
The CKD solenoid valve includes a valve body, a ball core, a valve seat, a shaft, and a guide sleeve. Its characteristic is that the ball core adopts a fixed support structure, and a protrusion is provided at the contact point between the product's valve seat and the ball core. A lip seal is installed on the sealing surface between the product's valve seat and the ball core; A seal is installed on the shaft next to the guide sleeve of the product. The technical solution of this product solves the problems of unreliable sealing, easy detachment of the surface hardening layer of the sealing pair, and high torque of the GSP process coal powder conveying special ball valve. At the same time, it solves the problem of easy damage to the guiding part and improves the valve's ability to resist abnormal jamming, without the need for a dedicated gas pipeline for blowing.
It is a widely used valve in pipelines, mainly used to connect and disconnect media. Not suitable for regulating the flow rate of the medium, but can determine the flow rate based on the height of the valve stem (such as elastic seat seal gate valves equipped with opening and closing scales for fire protection). Compared to other valves, gate valves have a wider range of applications for pressure, temperature, diameter, and other requirements.
CKD solenoid valves can be divided into three types based on their internal structure: wedge type single gate plate, elastic gate plate, double gate plate, and parallel gate plate.
According to the different valve stem supports, it can be divided into rising stem gate valves and hidden stem gate valves.
The main performance of CKD solenoid valve includes:
1. The valve has low fluid resistance. Due to the straight through valve body of the gate valve, the flow direction of the medium does not change, so the flow resistance is smaller compared to other valves.
2. The sealing performance is better than that of a globe valve, and the opening and closing are also easier than that of a globe valve.
3. Widely applicable, in addition to steam, oil and other media, it is also suitable for media containing granular solids and high viscosity, as well as for use as vent valves and valves in low vacuum systems.
4. CKD solenoid valve is a valve with dual flow direction, which is not limited by the flow direction of the medium, so it is suitable for pipelines where the flow direction of the medium may change, and it is also easy to install.
The main performance drawbacks of CKD solenoid valves are:
1. The exterior design has high dimensions and long opening and closing times. When opening, the valve plate needs to be lifted to the upper part of the valve chamber, and when closing, the valve plate needs to be fully lowered into the valve seat, so the opening and closing stroke of the valve plate is large and the time is long.
2. Due to friction between the two sealing surfaces of the CKD solenoid valve plate and seat during the opening and closing process, the sealing surface is prone to scratches, which affects the sealing performance and service life, and is not easy to repair.
Performance comparison of several different structures of electric gate valves:
(1) Wedge type single gate electric gate valve
a、 The structure of the gate valve is simpler than that of the elastic gate valve
b、 At higher temperatures, the sealing performance is not as good as that of elastic gate valves or double gate valves.
c、 Suitable for high-temperature media that are prone to coking.
(2) Special form of CKD solenoid valve. Compared with wedge gate valves, it has better sealing performance at high temperatures and is less likely to get stuck when the gate is heated;
b、 Suitable for steam, high-temperature oil products, and oil and gas media, and suitable for areas with frequent switching.
c、 Not suitable for media that are prone to coking.
(3) Double gate electric gate valve
a、 The sealing performance is better than that of wedge gate valves, and it still has good sealing performance when the inclination angle of the sealing surface and the fit of the valve seat are not very accurate.
b、 After the sealing surface of the gate is worn, the metal pad at the bottom of the spherical top can be replaced and used. Generally, there is no need to weld or grind the sealing surface, which is not available for single gate and elastic gate.
c、 Suitable for steam, high-temperature oil products, and oil and gas media, and suitable for areas with frequent switching.
d、 Not suitable for media that are prone to coking.
(4) Parallel electric gate valve
a、 The sealing performance is inferior to other forms of gate valves.
b、 Suitable for media with low temperature and pressure.
c、 The processing and maintenance of the sealing surface of the gate and valve seat are simpler than other forms of gate valves.
The difference between CKD solenoid valve and concealed electric gate valve:
CKD solenoid valve drives the opening and closing of the gate plate through the up and down lifting of the valve stem. The transmission thread of the rising stem gate valve is located at the top of the valve stem bracket, so the opening and closing position of the gate plate can be determined by the position of the valve stem. The transmission thread is also convenient for daily lubrication and maintenance, and is not corroded by fluids. The disadvantage is that it requires a relatively large installation space.
The transmission thread of CKD solenoid valve is located inside the valve body, saving space for the valve stem bracket, thus reducing the overall height of the valve. For those that require clear opening and closing positions, opening and closing scales can be installed above the valve cover, which is suitable for small spaces such as underground sewers (such as underground concealed gate valves), pipe trenches, or places with high dust content.