The temporary electricity system should adopt the system of "three-level control and two-pole protection", that is, adopt the total distribution box , distribution box and switch box three levels of control, and distribute the distribution at the same time in the main distribution box and the switch box respectively Leakage protection implement protection Under normal circumstances, electrical equipment can only be wired from the switch box In practice, some construction units because of a certain electrical equipment and distribution box closer to the distribution of power distribution box directly plexus This is not safe.
According to "safety norms" provisions from the wire under the lead wire into the distribution box should be used to wear protection and through the box into the line, the upper end of the protection pipe to do waterproof elbow some construction site but directly under the poles plus cross-dressing, the use of porcelain Wiring leads directly from above. Wire into and out of the box without sheath, no waterproof elbow. This approach is not desirable at the same time in the construction site, we often see the wiring at random distribution box usually not locked or locked but the key is not a special management = into and out of the chaos of the line does not divide into bundles, not Plus protection tube, the length of the missing, chaotic chaos then the power supply, the power cord hooked directly on the knife switch on the box is not standardized wiring, the conductor cut too long, the conductor exposed, "chicken legs line" serious cabinets cabling and Electrical switch layout does not meet the requirements Knife switch porcelain cover lost or nut incomplete A gate multiple machines, or even across the leakage protector Direct knife switch Leakage protection under a relay box with multiple residual wire head, residual melt gadgets And so on, and even stacking shoes and hats, food and other debris has been removed load line is still thrown in the box, naked thread close to the switch electrical In addition, the distribution box layout Lighting and wiring problems Construction site lighting is characterized by more, Wide range, mobility, temporary strong, so that the scene lighting power management is difficult, prone to accidents in humid places and places easily accessible lighting power supply voltage not less than, the use of mobile Lighting occasions, the power supply voltage must not exceed and can not be transformed from the autotransformer transformer, and the other wet places should also be used sealed waterproof dustproof.
However, what we saw is that in the stage of foundation plastering, the ground is extremely damp, and workers do not need to cut off the power and hold the hand-held illumination Laying the line away from the ground, arbitrarily placed on the ground chaos pull pull = aisle at the tube without protection, the bucket on the coming and going, and even some of the site using aluminum core sheath line cord for power lines and lighting and some wires Lighting tied to the wire, the iron frame, the right tree In addition, the aging of the lighting line is serious, the insulation is broken = the middle of the lighting line connector, the connector is not protected Lighting lines No switch box, no knife switch , And the lighting lines directly linked to the other equipment on the knife, or lighting circuit to bypass the leakage protector connected to the knife switch on the site of temporary lighting facilities layout is too low, free to break joints, like spider-like cable , And even some people hang clothes on it and so on. These violations are not uncommon, a lot of hidden dangers, urgent need to cause the construction unit heads attach great importance.
The use of molds has a life span. When the use of a pair of molds exceeds its life span, the molds should be replaced in time, so the mold production process has certain repeatability.
Milling, boring, drilling, reaming, tapping and other processes are also used in regular mold processing.
The main material of the mould is high-quality alloy steel. Some moulds with a long service life are often made of Crl2, CrWMn and other ledeburite steels. The production and processing of this material is very strict, so the processing process cannot be ignored. The thermal deformation treatment is also an aspect that needs to be taken seriously in the processing. To sum up, when selecting the airport, the processing conditions should be met as much as possible, such as strong functionality, high accuracy of machine tool, good rigidity, good thermal stability, and anti-type function.
Some surface shapes are composed of multiple curved surfaces, such as automobile cover parts, aircraft, parts, toys, household appliances, etc., so the surface of the mold cavity is very easy to be complicated, and some can be processed through mathematical calculation.
Some molds have neither drawings nor data in the production process, and can only be imitated through physical objects, which requires high imitation accuracy and no deformation.
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