Hard hat performance test is an important indicator for detecting protective effect of hard hat

In the production work, accidental fall injuries and human accidents occur from time to time. The damage to the human body caused by falling objects is mainly caused by the impact of acceleration. How much does the human body withstand the momentary impact? According to relevant research data from abroad, the human cervical vertebrae will be broken when 4900 N, and the brain will flow out, which will endanger life. The shorter the action time, the longer the impact distance and the heavier the impact drop, the greater the impact force. When an impact injury accident occurs, the impact force is generally much greater than 4900 N. This requires the worker to wear a helmet that has been tested by a helmet impact absorption performance tester to prevent the fall from the human body.
This kind of accident is characterized by sudden and strong, not easy to dodge, at the same time, the action time is short, the impact force is great, especially the falling object from top to bottom, the impact process only occurs in a moment. The accidents occurred in construction, mining, metallurgy, mining, oil exploration, tunnels and other industries. Once a shock accident occurs, the head is the first one with the highest probability of injury. The head is the nerve center of the human body, and the thinnest part of the skull is only about 2mm. Once the head is impacted by an external force, it may cause serious concussion, intracranial hemorrhage, meningeal contusion, skull injury and other serious injuries, resulting in human body dysfunction, ranging from disability, to life-threatening. Therefore, the heads of workers in the workplace must be protected, and the important items for head protection are the helmets tested by the helmet impact absorption tester.
A hat that protects the human head from damage caused by falling objects and other specific factors is called a safety helmet. It consists of a cap shell, a cap liner, a chin strap, and other accessories. The cap shell is composed of a shell, a cap, a brim, a top rib, etc. The cap lining is a general term for the internal parts of the cap shell, and is composed of a cap hoop, a suction belt, a lining tape, and a cushion device, and the chin strap is attached to the chin. The fixed-function strap consists of a strap and a locking card.
The protective effect of the hard hat tested by the helmet impact absorption tester is that when the operator is impacted or squeezed by a falling object or a hard object, the impact force is reduced, and the damage to the human head is eliminated or reduced. . Theoretically speaking, during the impact process, that is, from the instant when the falling object contacts the head, the falling object disengages from the cap shell, and the various components of the helmet (hat shell, cap liner, socket, reins, cushion, etc. Firstly, the impact force is decomposed, and then most of the impact force is absorbed through the elastic deformation, plastic deformation and reasonable destruction of each part, so that the impact force acting on the human head is less than 4900 N, thereby playing a protective role. This performance of the helmet is called impact absorption performance, and it is one of the important indicators for judging whether the helmet is qualified or not. The device that detects the impact absorption performance of the helmet is the helmet impact absorption performance testing machine, and must be selected for our personal safety. After passing the helmet impact absorption tester, the qualified helmet is tested.
This article is an article of Qingdao Zhongbang Instrument Co., Ltd. If you need to reprint it, be sure to add the source of the description. Reproduce the misappropriation without permission.

"Gravity Die Casting. A permanent mould casting process, where the molten metal is poured from a vessle of ladle into the mould, and cavity fills with no force other than gravity, in a similar manner to the production of sand castings, although filling cn be controlled by tilting the die."

Gravity Die Casting

Sometimes referred to as Permanent Mould, GDC is a repeatable casting process used for non-ferrous alloy parts, typically aluminium, Zinc and Copper Base alloys.

The process differs from HPDC in that Gravity- rather than high pressure- is used to fill the mould with the liquid alloy.

GDC is suited to medium to high volumes products and typically parts are of a heavier sections than HPDC, but thinner sections than sand casting.

There are three key stages in the process.

  1. The heated mould [Die or Tool] is coated with a die release agent. The release agent spray also has a secondary function in that it aids cooling of the mould face after the previous part has been removed from the die.
  2. Molten metal is poured into channels in the tool to allow the material to fill all the extremities of the mould cavity. The metal is either hand poured using steel ladles or dosed using mechanical methods. Typically, there is a mould [down sprue" that allows the alloy to enter the mould cavity from the lower part of the die, reducing the formation of turbulence and subsequent porosity and inclusions in the finished part.
  3. Once the part has cooled sufficiently, the die is opened, either manually or utilising mechanical methods.

Advantages

  • Good dimensional accuracy
  • Smoother cast surface finish than sand casting
  • Improved mechanical properties compared to sand casting
  • Thinner walls can be cast compared to sand casting
  • Reverse draft internal pockets and forms can be cast in using preformed sand core inserts
  • Steel pins and inserts can be cast in to the part
  • Faster production times compared to other processes.
  • Once the tolling is proven, the product quality is very repeatable.
  • Outsourced Tooling setup costs can be lower than sand casting.

Gravity Casting Parts

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