Globe Valves Sealing materials are often sealed shaft seals that require improved sealing and pressure ratings for machining accuracy and surface roughness in order to close metal and metal seal shut-off valves. However, the shaft seal is better. A view of the high pressure globe valve (p 300MPa) should be sealant method, the main linear sealing surface. The so-called plastic seal, pressure seal method is equivalent to sealing soft materials, combined with close contact with the surface yield limit, the use of plastic deformation of soft materials and blocked the rough surface of the hardware, the form and the approximate ideal is a soft output limit Force, keep sealed. Stem seal axial force depends on the total force of the valve to determine the key parameters of the total force seal sealing pressure. However, in the case of a dead-end spool seal, the axial pressure at qq is reduced by the seal pressure generated by the seal being able to softer the material in the Irrawaddy Delta. The yield constraint is whether a medium-pressure seal ratio must equal the pressure issue. This article will discuss the Irrawaddy The proper value of the delta. Qq It is considered that the clearance to prevent leakage of liquid must be 0.003 μm smaller from the point of view of the difference between the sealing surfaces based on the diameter smaller than the size of the medium molecules to ensure that the battery does not leak. However, even if the peak height of a metal surface is still above 0.05μm, the ideal aircraft must be fitted with some interface, force size and sealing material with a soft sealing surface roughness σ. When the pressure seal surface 40MPa, qq but for σ> s 900MPa sealing material 300MPa level, ultra-valve, in addition to elastic fracture mechanics from the point of view, from the required force σ-pseudo-convex, Ra0.05μ sub-meters above, Sealing mechanism considerations. Therefore, for the 900MPa ultra-high pressure on the sealing valve σ, sealed in Ra0.05μm roughness must be above. And the treatment of hip joint WC cemented sealing due to its nature to increase the sealing pressure ratio of the surface of the sealing surface with more fragile pressure waves can greatly increase the axial force that allows the seal to produce cracks in the valve used by small fish , The company due to improper adjustment and axial force caused by the fracture example) seat, therefore, the sealing surface roughness is higher than Ra0105μ sub-meter. Only within this range, the calculation of the axial force of type (13) can be used. Ultra-closing valve sealing mechanism, narrow surface plastic two types of lines. The axial force is proportional to the width due to the seat disc (or the cold hardening phenomenon after deformation of the sealing surface.) A 1/2-inch 15 mm ball valve sealing material is a cemented carbide acetabular rotational osteotomy Treatment of WC seal, a certain flatness evaluation, axial force calculation formula, with a certain range.
Tapping Screw
Although there are many types of tapping screws, they all have the following similarities:
(1) are generally made of carbonized carbon steel (accounting for 99% of total production). It can also be made of stainless steel or non-ferrous metals.
(2) The product must be heat treated. Carbon steel tapping screws must be carbonized and stainless steel tapping screws must be solution hardened. In order to make tapping screws to meet the requirements of the standard of mechanical properties and performance.
(3) The product surface hardness is high, the core toughness is good. That is, "soft inside strong outside". This is a major feature of tapping Screw performance requirements. If the surface hardness is low, it can not be screwed into the matrix; If the core toughness is poor, a twist will break, can not be used. So "inside soft outside steel" is self-tapping screw to meet the use of performance, very important requirements.
(4) The surface of the product needs surface protection treatment, generally electroplating treatment. Some product surface must be treated by phosphate (photostatting), such as wall panel self - tapping screws for photostatting.
(5) Production by cold heading process. It is recommended to use high-speed cold heading machine and high-speed wire rolling machine or high-speed planetary wire rolling machine. High speed is emphasized here to ensure product quality. Only the head of tapping screw produced by high-speed machine is well formed and the thread quality is high.
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