Selvitys meijerin ja sille säännöstelymääräysten mukaisen selvityksen tekevien hankintaliikkeiden aikana vuonna 194… hankkimista, valmistamista, luovuttamista ja varastossa olevista maitotaloustuotteista

29 x 42 cm

Selvitys meijerin ja sille säännöstelymääräysten mukaisen selvityksen tekevien hankintaliikkeiden aikana vuonna 194… hankkimista, valmistamista, luovuttamista ja varastossa olevista maitotaloustuotteista

29 x 42 cm

Paikkatiedon verkko-oppiminen : PaikkaOpin oppimisympäristö

Teema: Opetuksen maantiede - Nuorten maantiede.

Uskonnolliset herätykset ja kulttuurinen sopeutuminen

Kirjallisuusarvostelu

Varsinaissuomalaisia kartanoita sekä säätyläistapakulttuuria

Kirjallisuusarvostelu

Kirkollisia vaikuttajia 1100-luvulta nykyaikaan

Kirjallisuusarvostelu

Laser cladding with scanning optics

Scanning optics create different types of phenomena and limitation to cladding process compared to cladding with static optics. This work concentrates on identifying and explaining the special features of laser cladding with scanning optics. Scanner optics changes cladding process energy input mechanics. Laser energy is introduced into the process through a relatively small laser spot which moves rapidly back and forth, distributing the energy to a relatively large area. The moving laser spot was noticed to cause dynamic movement in the melt pool. Due to different energy input mechanism scanner optic can make cladding process unstable if parameter selection is not done carefully. Especially laser beam intensity and scanning frequency have significant role in the process stability. The laser beam scanning frequency determines how long the laser beam affects with specific place local specific energy input. It was determined that if the scanning frequency in too low, under 40 Hz, scanned beam can start to vaporize material. The intensity in turn determines on how large package this energy is brought and if the intensity of the laser beam was too high, over 191 kW/cm2, laser beam started to vaporize material. If there was vapor formation noticed in the melt pool, the process starts to resample more laser alloying due to deep penetration of laser beam in to the substrate. Scanner optics enables more flexibility to the process than static optics. The numerical adjustment of scanning amplitude enables clad bead width adjustment. In turn scanner power modulation (where laser power is adjusted according to where the scanner is pointing) enables modification of clad bead cross-section geometry when laser power can be adjusted locally and thus affect how much laser beam melts material in each sector. Power modulation is also an important factor in terms of process stability. When a linear scanner is used, oscillating the scanning mirror causes a dwell time in scanning amplitude border area, where the scanning mirror changes the direction of movement. This can cause excessive energy input to this area which in turn can cause vaporization and process instability. This process instability can be avoided by decreasing energy in this region by power modulation. Powder feeding parameters have a significant role in terms of process stability. It was determined that with certain powder feeding parameter combinations powder cloud behavior became unstable, due to the vaporizing powder material in powder cloud. Mainly this was noticed, when either or both the scanning frequency or powder feeding gas flow was low or steep powder feeding angle was used. When powder material vaporization occurred, it created vapor flow, which prevented powder material to reach the melt pool and thus dilution increased. Also powder material vaporization was noticed to produce emission of light at wavelength range of visible light. This emission intensity was noticed to be correlated with the amount of vaporization in the powder cloud.

Persönlichkeiten der ungarischen Sprachwissenschaft

Kirjallisuusarvostelu