The definition of high frequency welding
bourne
Boreway machinery
2015-09-26 17:36:31
High frequency welding, it is the use of high frequency
current produced by the skin effect and the adjacent effect, steel and other
metal materials butt up a new type of welding process. The emergence of high
frequency welding technology and mature, it is straight seam welded pipe (ERW)
the key to the production process. High frequency welding quality is good or
bad, directly affects the whole strength of the welded pipe products, the
quality level and production speed. In diamond tools, diamond saw blade cutter
welding using this technique.
The so-called high frequency, which is relative to
the frequency of 50 hz alternating current, generally refers to the 50 KHZ to
400 KHZ high frequency current. And the high frequency current through the metal
conductor will produce two kinds of peculiar effects: skin effect and proximity
effect, high frequency welding is in using the two kinds of effect for the
welding of steel pipe. Then, the two effects is how to return a
responsibility?
Skin effect Refers to a certain frequency of alternating current through a
conductor, the current density is not evenly distributed in all the
cross-section of the conductor, it will mainly to concentrate in the surface of
the conductor, the current in the conductor surface density is big, inside the
conductor of the density is small, so we vividly called: "skin effect". Skin
effect is usually to measure with current penetration depth, penetration depth
value is smaller, the skin effect more significant. The penetration depth and
the conductor is directly proportional to the square root of the resistivity,
and the frequency and the permeability is inversely proportional to the square
root. In layman's terms, the higher the frequency, current, the more
concentrated on the surface of steel plate; The lower the frequency, surface
current, the more dispersed. Must pay attention to: although steel is a
conductor, but its permeability will fall with a rise of temperature, that is,
when the steel plate temperature, permeability will decline, skin effect will
decrease.
Proximity effect Refers to the high frequency current in the conductor of two
adjacent reverse flow, the current will be similar to the two conductors on the
edge of concentrated flow, even if the two conductors in addition there is a
short edge, current does not flow along the shorter route, we call this effect:
the "proximity effect.
